DESCRIPTION

Process and fibre processing apparatus for the preparation of a pulp additive from a sugar beet starting material

The invention pertains to a process for the production of a pulp additive from a sugar beet starting material, a fibre processing apparatus being suitable for said process, in particular for the preparation of a pulp additive from a sugar beet starting material, and in particular for the defibrillation and/or defibering of cellulose fibres in the sugar beet starting material as well as to a pulp additive obtainable from said process and a packaging material comprising said pulp additive.

The progressing endeavour to substitute mineral oil-based materials, in particular plastics, by renewable alternatives requires the development and improvement of new alternative plant-based raw materials and methods for their production. Of particular interest in this regard are plant-based raw materials which can be produced from industrial by-products and waste materials and which can subsequently be used for the preparation of value-added products. Such new raw materials are ideally not only suitable to equivalently substitute existing materials but also to provide particular advantages with respect to their target application. One of such raw materials are cellulose microfibres (CMF) and cellulose nanofibres (CNF) which are obtained by defibrillation of cellulose fibres from plant-based materials. The main applications of cellulose fibres are the paper industry, the clothing industry, the biomedical field, and the preparation of engineered materials.

The conversion of compositions comprising cellulose fibres into compositions comprising defibrillated cellulose fibres for paper making purposes is known.

Processes for opening, beating or defibrillating pulp fibres to obtain fibrillation, increased surface area, increased accessibility and fine particle size have long been known. Ball mills are used for preparing cellulose of several tens of microns in dimension. Studies have indicated that such ball milling breaks the chemical bonds of the cellulose during the dividing process.

It is also known to grind cellulose in water under pressure to produce a micro-cellulose with a particle size of less than one micron. In the case of cellulose derivatives, cold milling of the derivatives in liquid nitrogen is also disclosed in the prior art. Sonic pulverization with a ball mill is also a known method of producing cellulose in extremely fine particle size. Finely divided celluloses are also produced in the traditional processes used in manufacturing fibreboard and paper pulp. Normally, however, these traditional processes involve the use of additional chemical treatment to cellulose pulps, as for example, acid hydrolysis, which chemically alter or degrade the prepared cellulose pulps.

In the paper industry, it is known that paper strengths are directly related to the amount of beating or refining which the fibres receive prior to formation. However, beating and refining as practiced in the paper industry are relatively inefficient processes and large amounts of energy are expended to gain relatively minor amounts of fibre opening and fibrillation.

Sugar beet (Beta vulgaris) is an agricultural crop whose root contains high levels of sucrose and is used as a major source of sugar in temperate zones. For the production of sugar from the sugar beet roots, the roots are initially cleaned to remove soil and debris and subsequently mechanically sliced into small pieces called cossettes. The cossettes are usually desugared at elevated temperature in a continuous counter-current extraction process using water. The extracted raw juice comprising about 15% sugar and further natural components of the sugar beet is then subjected to purification, concentration and crystallization to finally yield sucrose. The desugared cossettes (sugar beet pulp) obtained as a by-product of beet sugar production are typically used as domestic livestock feed or for biogas production. The sugar beet pulp may be pressed to remove excess water so as to achieve a dry matter content of about 20 to 28 %. It may, conventionally after pressing, also be dried and then pressed into pellets. Dried sugar beet pulp is easy to store and transport and may be grinded or mixed with other components. These products are mainly used for feeding of ruminants. It is also known to mix the desugared beet pulp with sugar beet molasses, in particular before drying. Such process increases the sucrose content of the sugar beet pulp and thus its nutritional value.

Sugar beet pulp comprises a high proportion of fibre consisting of roughly about one third cellulose, about one third pectin and about one third hemicellulose and is therefore also a promising industrial by-product for the production of cellulose fibres, which are used as a renewable raw material, for instance in the texile and paper industry.

From EP 0644293 Al it is known to use sugar beet pulp, optionally in mixture with white recycled paper, for the production of paper. The sugar beet pulp used has been ground in a hammer mill, sieved to obtain particles with an average size of 50 pm and the flour obtained is employed in the paper making process. Fiserova et al. (Cellulose Chem. Technol. 41 (2007), 283 - 289) discloses that sugar beet pulp can be used after disintegration into smaller particles for the production of paper, in particular as a partial substituent of wood fibres. The document discloses that the addition of wet beaten sugar beet pulp to recovered fibres is recommended over the use of dry disintegrated sugar beet pulp, in particular up to 15 % sugar beet pulp in a furnish.

Gigac et al. (International Sugar Journal 111 (2008), 20 - 26) discloses enzyme-hydrolysed sugar beet pulp and various other preparations made from sugar beet pulp including dry and wet pretreated sugar beet pulp for the production of paper. Gigac et al. discloses that the addition of hydrolysed beet pulp to a spruce stone groundwood furnish is favourable over the use of nonhydrolysed beet pulp in the preparation of hand sheets. It is disclosed that the addition of nonhydrolysed and hydrolysed beet pulps to stone groundwood furnish is superior over beaten stone groundwood furnish on tensile index. According to Fiserova et al. (Wood Research, 52 (2007), 59 - 74) extruded and dried 1 to 6 mm particles of sugar beet pulp beaten after soaking in water for 2 hours to a beating degree of 50 °SR (Schopper-Riegler) increases the specific bond strength and qualifies as a partial replacement of recovered fibres.

WO 97/30215 Al discloses the use of fermented sugar beet pulp for making paper or cardboard, wherein sugar beet pulp is subjected to a lactic acid fermentation and micronized pulp is isolated.

Various methods and apparatus are known in the art for providing means to defibrillate cellulose fibres. In particular, two methods are commonly used for the defibrillation of cellulose fibres in plant-based materials. One method includes the use of a screw processor, whereby a single, twin or multi screw arrangement is provided. Another commonly used method includes the use of a plate or conical refiner. These techniques are often used as a separate phase of a larger scale refining system.

Plate refining has the advantage of using larger, more efficient grabbing / tearing / shearing plate profiles to achieve fibre size reduction in a relatively small area at the centre of the refining plates adjacent to the fibre feed and at which the fibre is introduced. The fibre then moves towards the outside of the refining plate and, as it does so, is reduced in size and the outer or primary fibre wall is delaminated (defibrillation). The nature of plate refining is that it is sufficiently economic with regards to power to allow several successive repeats of use of the single-phase system.

An alternative type of apparatus and method is the use of a screw processor. However, the rapid treatment of fibre as a sequence in an integrated de-fibering and/or defibrillating screw processor is difficult to achieve because the elements that are conventionally available are limited in their capacity and/or may cause fibre damage.

There are also a number of difficulties involved in being able to achieve further micro and nanoscale defibrillation of cellulosic fibres using a screw processor. This can be due to several factors, such as the conventional screw elements being designed principally for use with other media, such as plastics, pharmaceuticals and foodstuffs, as opposed to cellulose fibres and as a result of this, these elements are typically designed around the fluid dynamics of plastics, food and pharmaceutical materials and are focused on conveying, mixing, blending, pressure generation and pressure relief. This means that they are not generally suitable for de-fibering and/or de-fibrillation or further treatment of cellulose fibre to macro/micro/nano-scale, as the active contact surface area of these elements is relatively small. Furthermore, the active surface areas of the conventional elements are typically located on the outer surfaces only which are typically the surfaces which are substantially parallel with the axis of the shaft on which the elements are mounted and about which axis the elements are rotated. This therefore underutilises other parts of the elements which are conventionally provided to be relatively smooth.

Another problem that exists in current screw processing apparatus is that the level of intensification of the work performed tends to be centred around the use of backpressure or dam elements, which create a form of barrier by reducing the gap size through which material must pass and which therefore act to “trap” the cellulose fibres at particular portions of the twin screw apparatus. Extra milling of the fibre using smooth faces of the elements occurs as a consequence of the fibres attempting to pass the backpressure elements and this can cause the fibre integrity to be degraded and the overall quality of the resulting mix can be diminished by the unintentional separation of the macro/micro/nano elements of each fibre. The use of back pressure or dam elements can also encourage the separation of the liquid and solid components of the material as the liquid and smaller particles are able to pass the element restriction to leave a dry mass on the upstream side of the process such that the overall integrity of the final fibre mass is compromised and the end product becomes a series of separate fibres at differing scales, many of which are nonfunctionalised debris or “fines”.

It is therefore a technical problem underlying the present invention to provide an improved process and apparatus for the de-fibering and/or subsequent defibrillation of cellulose fibres, which is particularly suitable for preparing a pulp additive from a sugar beet starting material and which overcomes the aforementioned problems associated with fibre processing processes and apparatuses of the prior art. It is a further a technical problem underlying the present invention to provide a pulp additive from a sugar beet starting material which is suitable for use in the preparation of packing material, in particular to provide a pulp additive from a sugar beet starting material, which is suitable to provide a packing material with similar or even improved properties in comparison to conventional packing materials prepared from wood-based lignocellulosic raw materials, in particular to provide a pulp additive from a sugar beet starting material which is suitable to be used for the preparation of packing material having comparable or improved tensile strength, burst resistance, tear resistance, and/or compression strength in comparison to conventional packing materials prepared from wood-based lignocellulosic raw materials.

The present invention solves the above-identified technical problems by the provision of the teaching according to the claims and the accompanying description.

Further preferred embodiments of the present invention are the subject-matter of the dependent claims.

The present invention is directed to a process for the production of a pulp additive from a sugar beet starting material said process comprising the steps of: a) providing a sugar beet starting material, in particular a precursor obtained from the sugar beet starting material, b) feeding the starting material into the fibre processing apparatus according to the present invention so as to obtain a precursor, c) extruding the precursor in the fibre processing apparatus to obtain the pulp additive, and d) exiting the pulp additive from the outlet.

Thus, the present invention specifically uses a particular starting material for the production of an advantageous pulp additive which is a sugar beet starting material and which sugar beet material is subjected to an extrusion process employing a specific fibre processing apparatus, in particular a fibre processing apparatus characterised by the presence of textured refining elements.

The processing of sugar beet starting material according to the process of the present invention, and thus, the de-fibering and/or defibrillation of cellulose fibres of the starting material in the fibre processing apparatus according to the present invention results in the yield of a pulp additive which is advantageously suitable for the at least partial substitution of conventionally used cellulose-fibre containing compositions obtained from wood-based lignocellulosic raw materials. In this way, the process according to the present invention allows conversion of sugar beet starting materials occurring as by-products during sugar production into a value-added renewable raw material which can be used in different applications, such as in the textile and paper industry, in particular for the production of packing materials with increased sustainability. Advantageously, the pulp additive obtained by the method according to the invention allows at least the partial substitution of lignocellulosic wood-based raw materials conventionally used in the production of paper and board products while maintaining or even improving the properties of the products, in particular tensile strength, burst resistance, tear resistance, and/or compression strength of the products.

The particular suitability of the pulp additive obtained by the method according to the invention is achieved by subjecting a sugar beet starting material which is rich in cellulose fibre to mechanical manipulation using specific surface-textured refining elements in the processing sections arranged along the longitudinal axis of at least one shaft in the fibre processing apparatus according to the present invention. Said at least one shaft comprises at least one fibre modification section which fibre modification section comprises at least one refining element comprising a forward surface, a rearward surface and a peripheral surface, and wherein at least one of the forward surface, the rearward surface and the peripheral surface is at least partially textured. The progressive modification of cellulose fibres by the surface-textured refining elements in the plurality of processing sections along the flow path of the starting material from the at least one inlet to the outlet of the apparatus increases the efficiency of the mechanical manipulation and the fibre residence time and associated therewith the degree of defibrillation of the cellulose fibres in the sugar beet starting materials in comparison the known fibre processing apparatuses.

The process for the production of a pulp additive from a sugar beet starting material according to the present invention is characterized in that a sugar beet starting material is provided which is fed into the fibre processing apparatus according to the present invention so as to preferably build-up a forward pressure in a feeder section of the fibre processing apparatus. Such forward pressure can for example be provided by feeding stuffing screws in the case of force feeding or by transport screws. Particularly preferred, no forward pressure except for the pressure exerted in the feeder section is used for the movement of the material to be processed in the processing sections of the fibre processing apparatus. In particular embodiments, and in dependency on the sugar beet starting material used, in can be preferable to even use backpressure in the fibre modification sections so as to retain the material in the fibre modification sections for a sufficient time and to achieve a desired degree of defibrillation. The process and apparatus according to the present invention advantageously allow an efficient processing, in particular an efficient de-fibering and/or defibrillation, of cellulose fibres from different sugar beet starting materials, in particular from sugar beet starting materials with different dry matter contents, preferably with different degrees of dryness due to the extraction of water from a sugar beet pulp by pressing and/or drying procedures.

In a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is sugar beet pulp, preferably unfermented or fermented sugar beet pulp, hereinafter also called sugar beet pulp silage. Unfermented sugar beet pulp is preferably pressed sugar beet pulp, NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp, dried sugar beet pulp and non- melassed sugar beet pulp, dried non-melassed sugar beet pulp.

In a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a dried sugar beet pulp, preferably a pressed and dried sugar beet pulp, most preferably a NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp or a HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp.

Preferably, the sugar beet starting material provided in step a) is a dried sugar beet pulp, pressed sugar beet pulp, or sugar beet pulp silage.

In a preferred embodiment of the present invention, the sugar beet starting material has not been ensilaged. Preferably, the sugar beet starting material is not a fermented sugar beet starting material.

In a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is selected from the group consisting of pressed sugar beet pulp, NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp, dried sugar beet pulp, non-melassed sugar beet pulp, dried non-melassed sugarbeet pulp, and sugarbeet pulp silage, in particular NTT sugarbeet pulp silage. Particularly preferred, the sugar beet starting material provided in step a) is NTT sugar beet pulp dried at a temperature of 30 to 115 °C, preferably 50 to 90 °C. According to a preferred embodiment of the present invention, the sugar beet starting material has a dry matter content of at least 20 wt.-%, preferably 25 wt.-%, preferably at least 30 wt.-%, preferably at least 35 wt.-%, preferably at least 40 wt.-%, preferably at least 45 wt.-%, preferably at least 50 wt.-%, preferably at least 55 wt.-%, preferably at least 60 wt.-%, preferably at least 65 wt.-%, preferably at least 70 wt.-%, preferably at least 75 wt.-% (based on overall weight of the material).

In a further preferred embodiment, the sugar beet starting material has a dry matter content of at most 96 wt.-%, preferably 90 wt.-%, preferably 85 wt.-%, preferably 80 wt.-%, preferably at most 75 wt.-%, preferably at most 70 wt.-%, preferably at most 65 wt.-%, preferably at most 60 wt.-%, preferably at most 55 wt.-%, preferably at most 50 wt.-%, preferably at most 45 wt.-%, preferably at most 40 wt.-% (based on overall weight of the material).

In a preferred embodiment of the present invention, the sugar beet starting material has a dry matter content from 20 to 96 wt.-%, preferably 20 to 90 wt.-%, preferably 20 to 85 wt.-%, preferably 20 to 80 wt.-%, preferably 20 to 65 wt.-%, preferably 25 to 55 wt.-%, preferably 30 to 50 wt.-%, preferably 35 to 45 wt.-% (based on overall weight of the material).

In a preferred embodiment of the present invention, the sugar beet starting material has a dry matter content from 50 to 65 wt.-%, preferably 50 to 60 wt.-%, preferably 55 to 65 wt.-%, preferably 55 to 60 wt.-% (based on overall weight of the material).

In a particularly preferred embodiment of the present invention, the sugar beet starting material is a NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, preferably a NTT sugar beet pulp silage, having a dry matter content from 30 to 55 wt.-%, preferably 35 to 50 wt.-%, preferably 40 to 47 wt.-% (based on overall weight of the material).

In a preferred embodiment of the present invention, the NTT sugar beet pulp is not an ensilaged NTT sugar beet pulp, in particular not a fermented NTT sugar beet pulp.

In a preferred embodiment of the present invention, the sugar beet starting material is a HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp having a dry matter content from 75 to 96 wt.-%, preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-%, (based on overall weight of the material). In a preferred embodiment of the present invention, the sugar beet starting material is a pressed sugar beet pulp having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the material).

In a preferred embodiment of the present invention, the sugar beet starting material is a sugar beet pulp silage having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the material).

In a preferred embodiment of the present invention, the pulp additive obtained in step d) has a dry matter content from 30 to 70 wt.-%, preferably 35 to 65 wt.-% (based on overall weight of the pulp additive).

In a particularly preferred embodiment of the present invention, the sugar beet starting material is a NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, preferably NTT sugar beet pulp silage, having a dry matter content from 30 to 55 wt.-%, preferably 35 to 50 wt.-%, preferably 40 to 47 wt.-% (based on overall weight of the material) and the pulp additive obtained by the present process steps a) to d) has a dry matter content from 30 to 65 wt.-%, preferably 35 to 60 wt.-%, , preferably 45 to 55 wt.-% (based on overall weight of the pulp additive).

In a preferred embodiment of the present invention, the sugar beet starting material is a HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp having a dry matter content from 75 to 96 wt.-%, preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-%, (based on overall weight of the material) and the pulp additive obtained by the present process steps a) to d) has a dry matter content from 50 to 75 wt.-%, preferably 55 to 70 wt.-%, preferably 58 to 68 wt.-%, preferably 55 to 65 wt.-% (based on overall weight of the pulp additive).

In a preferred embodiment of the present invention, the sugar beet starting material is a pressed sugar beet pulp having a dry matter content from 18 to 38 wt.-%, preferably 24 to 36 wt.-%, preferably 28 to 34 wt.-% (based on overall weight of the material the and the pulp additive obtained by the present process steps a) to d) has a dry matter content from 25 to 50 wt.-%, preferably 28 to 48 wt.-%, preferably 30 to 45 wt.-%, preferably 35 to 40 wt.-% (based on overall weight of the pulp additive).

In a further preferred embodiment of the present invention, the sugar beet starting material provided in step a) is fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein the at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the at least one fibre modification section and the at least one fibre transport section, so as to obtain a pulp additive, from the outlet in step d).

In a particularly preferred embodiment of the present invention, the sugar beet starting material provided in step a) is fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements and at least one fibre modification section is a reverse fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the fibre modification sections and the at least one fibre transport section, so as to obtain a pulp additive from the outlet in step d).

In a further preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp, preferably having a dry matter content from 75 to 96 wt.-%, preferably 80 to 95 wt.-%, most preferably 85 to 90 wt.-% (based on overall weight of the material), a NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, preferably having a dry matter content from 30 to 55 wt.-%, preferably 35 to 50 wt.-%, preferably 40 to 45 wt.-% (based on overall weight of the material), pressed sugar beet pulp, preferably having a dry matter content from 18 to 38 wt.- %, most preferably 24 to 36 wt.-% (based on overall weight of the material) or a sugar beet pulp silage, preferably having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.- % (based on overall weight of the material), which is fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein the at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the at least one fibre modification section and the at least one fibre transport section, so as to obtain a pulp additive, from the outlet in step d). In a particularly preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, preferably NTT sugar beet pulp silage, preferably having a dry matter content from 30 to 55 wt.-%, preferably 35 to 50 wt.-%, most preferably 40 to 47 wt.-% (based on overall weight of the material), which is fed into a fibre processing apparatus according to the present invention having a twin-screw processor including two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, preferably having a dry matter content from 25 to 55 wt.-%, preferably 30 to 50 wt.-%, preferably 35 to 45 wt.-% , most preferably 40 to 47 wt.-% (based on overall weight of the precursor), wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements and at least one fibre modification section is a reverse fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the fibre modification sections and the at least one fibre transport section, so as to obtain a pulp additive, preferably having a dry matter content of 35 to 65 wt.-%, preferably 40 to 60 wt.-%, most preferably 45 to 55 wt.-% (based on overall weight of the pulp additive) from the outlet in step d).

In a further preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp, preferably having a dry matter content from 75 to 96 wt.-%, most preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-% (based on overall weight of the material), which preferably is mixed with aqueous solution, in particular water, preferably before, during or after being fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), is fed into the fibre processing apparatus, preferably by force feeding, so as to obtain a precursor, preferably having a dry matter content from 40 to 70 wt.-%, preferably 45 to 65 wt.-%, most preferably 50 to 60 wt.-% (based on overall weight of the precursor), wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein the at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the at least one fibre modification section and the at least one fibre transport section, so as to obtain a pulp additive, preferably having a dry matter content of 50 to 75 wt.-%, preferably 55 to 70 wt.- %, most preferably 60 to 65 wt.-% (based on overall weight of the pulp additive) from the outlet in step d). According to a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a pressed sugar beet pulp, preferably having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the material), which is fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, preferably having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the precursor), wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements and at least one fibre modification section is a reverse fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the fibre modification sections and the at least one fibre transport section, so as to obtain a pulp additive having a dry matter content of 25 to 50 wt.-%, preferably 30 to 45 wt.-%, most preferably 35 to 40 wt.-% (based on overall weight of the pulp additive) from the outlet in step d).

In a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is a sugar beet pulp silage, preferably having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the material), which is fed into a fibre processing apparatus according to the present invention having a twin-screw processor with two rotatable shafts in step b), preferably by force feeding, so as to obtain a precursor, preferably having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the precursor), wherein the precursor is extruded in step c) in the fibre processing apparatus, wherein at least one fibre modification section is a pressure neutralised fibre modification section comprising at least one grouping of refining elements and at least one fibre modification section is a reverse fibre modification section comprising at least one grouping of refining elements, and which shafts comprise at least one bearing element between the fibre modification sections and the at least one fibre transport section, and wherein the fibre modification section optionally comprises at least one filter which is preferably arranged between fibre modification sections, more preferably after a feeding zone and before the reverse fibre modification section, most preferably before each reverse fibre modification section, so as to obtain a pulp additive from the outlet in step d).

The present invention requires in step b) the feeding of the starting material into the fibre processing apparatus according to the present invention so as to obtain a precursor. Such precursor is preferably formed as a result of the sugar beet starting material used and subjected to the feeding process, optionally of the sugar beet starting material being subjected to the feeding process and additionally added liquid, in particular water.

It has been found that the use of sugar beet starting material advantageously provides a high level of lubrication of the elements, in particular of the flow control elements and/or of the refining elements, arranged along the longitudinal axis of the at least one extruder shaft of the fibre processing apparatus of the present invention as the material passes along the apparatus. The high level of lubrication provided by the starting material to be processed allows the material to be fed into the fibre processing apparatus with a relatively high dry matter content of more than 40%, preferably more 50%. The possibility of feeding and efficiently processing a sugar beet starting material with a relatively high dry matter content in the fibre processing apparatus advantageously results in a pulp additive with a relatively low water content, preferably a water content of 50 % or less, preferably 45% or less, preferably 40% or less, and reduces the drying time of the pulp additive after extrusion and thereby improves economic efficiency.

In a preferred embodiment of the present invention, the sugar beet starting material provided in step a) is subjected to an extraction process in a step al) prior to step a).

According to a preferred embodiment of the present invention, the precursor obtained in step b) by feeding the starting material into the fibre processing apparatus has a dry matter content of 1 to 80 wt.-%, preferably 5 to 70 wt.-%, preferably 10 to 60 wt.-% (based on overall weight of the precursor).

In a particularly preferred embodiment of the present invention, the precursor obtained in step b) by feeding the starting material into the fibre processing apparatus has a dry matter content of 20 to 65 wt.-%, preferably 20 to 60 wt.-%, preferably 25 to 55 wt.-%, preferably 30 to 50 wt.-%, preferably 35 to 45 wt.-%, most preferably 40 to 45 wt.-% (based on the overall weight of the precursor).

In a preferred embodiment of the present invention, the precursor obtained in step b) by feeding the starting material into the fibre processing apparatus has a dry matter content of 40 to 60 wt.- %, preferably 40 to 58 wt.-% (based on overall weight of the precursor).

According to a preferred embodiment, a further cellulose-containing starting material is additionally provided in step a) and fed into the fibre processing apparatus in step b), so as to provide a precursor comprising a mixture of starting materials with a dry matter content from 20 to 65 wt.-% (based on overall weight of the precursor).

In a preferred embodiment of the present invention an aqueous solvent, in particular water, is provided additionally in step a) and is fed in step b) into the fibre processing apparatus together with the sugar beet starting material and/or is added in step c) during extrusion, in particular to adjust the dry matter content of the precursor to 20 to 65 wt.-%, preferably 20 to 60 wt.-%, preferably 25 to 55 wt.-%, preferably 30 to 50 wt.-%, preferably 35 to 45 wt.-%, most preferably 40 to 45 wt.-% (based on overall weight of the precursor).

In a preferred embodiment of the present invention an aqueous solvent, in particular water, is provided additionally in step a) and is mixed with the sugar beet starting material, in particular with the HTT sugar beet pulp, prior to, during and/or subsequent to feeding step b), so as to obtain a precursor having a dry water content from 40 to 70 wt.-%, preferably 45 to 65 wt.-%, most preferably 50 to 60 wt.-% (based on overall weight of the precursor).

In a preferred embodiment of the present invention, in step a) at least one additive is provided and fed into the process, preferably in a step a2) after step a) and prior step b) and/or in steps b), and/or c).

In a preferred embodiment of the present invention, the at least one additive is selected from the group consisting of minerals, colours, enzymes, polymers, in particular starch, and waterproofing agents. In a further preferred embodiment of the present invention, no additives are fed into the process.

According to a preferred embodiment of the present invention, the fibre processing apparatus comprises a single-screw processor.

In a preferred embodiment of the present invention, the fibre processing apparatus comprises a twin-screw processor, wherein the two extruder shafts are operating in a co-rotating mode.

In a preferred embodiment of the present invention, the sugarbeet starting material is fed into the fibre processing apparatus in step b) via volumetric or gravimetric dosing, belt feeding, or force feeding.

In a preferred embodiment of the present invention, the sugarbeet starting material is fed into the fibre processing apparatus in step b) under pressure. In a preferred embodiment of the present invention, the sugarbeet starting material is fed into the fibre processing apparatus in step b) by force feeding, preferably by using vertical or side feeding stuffing screws.

In a preferred embodiment of the present invention, the sugarbeet starting material is fed into the fibre processing apparatus in step b) with a feeding rate of at least 50 kg/h, preferably at least 100 kg/h, preferably at least 150 kg/h, preferably at least 200 kg/h, preferably at least 250 kg/h, preferably at least 300 kg/h, preferably at least 350 kg/h, preferably at least 400 kg/h, preferably at least 450 kg/h, preferably at least 500 kg/h (based on dry matter of the sugar beet starting material).

In a further preferred embodiment of the present invention, the sugar beet starting material is fed into the fibre processing apparatus in step b) with a feeding rate of at most 1000 kg/h, preferably at most 900 kg/h, preferably at most 800 kg/h, preferably at most 700 kg/h, preferably at most 600 kg/h, preferably at most 500 kg/h, preferably at most 400 kg/h, preferably at most 300 kg/h, preferably at most 200 kg/h (based on dry matter of the sugar beet starting material).

According to a particularly preferred embodiment of the present invention, the sugar beet starting material is fed into the fibre processing apparatus in step b) with a feeding rate of 50 to 1000 kg/h, preferably 100 to 800 kg/h, preferably 200 to 600 kg/h, preferably 250 to 500 kg/h, preferably 300 to 400 kg/h (based on dry matter of the sugar beet starting material).

In a preferred embodiment of the present invention, the precursor is extruded in step c) by rotating the at least one extruder shaft of the screw-processor at a speed of at least 50 rpm, preferably at least 100 rpm, preferably at least 150 rpm, preferably at least 200 rpm, preferably at least 250 rpm, preferably at least 500 rpm, preferably at least 750 rpm, preferably at least 1000 rpm, preferably at least 1250 rpm, preferably at least 1500 rpm.

In a further preferred embodiment of the present invention, the precursor is extruded in step c) by rotating the at least one extruder shaft of the screw-processor at a speed of at most 2000 rpm, preferably at most 1750 rpm, preferably at most 1500 rpm, preferably at most 1250 rpm, preferably at most 1000 rpm, preferably at most 900 rpm, preferably at most 800 rpm, preferably at most 700 rpm, preferably at most 600 rpm, preferably at most 500 rpm. In a preferred embodiment of the present invention, the precursor is extruded in step c) by rotating the at least one extruder shaft of the screw-processor at a speed of 50 to 2000 rpm, preferably 250 to 1500 rpm, preferably 750 to 1250 rpm.

In a preferred embodiment of the present invention, the process temperature of step c) is at least 60 °C, preferably at least 65 °C, preferably at least 70 °C, preferably at least 75 °C, preferably at least at least 80 °C, preferably at least 85 °C, preferably at least 90 °C, preferably at least 95 °C, preferably at least 100 °C, preferably at least 105 °C, preferably at least 110 °C, preferably at least 115 °C, preferably at least 120 °C. Preferably, the process temperature is at least in a temperature range to kill bacteria.

In a further embodiment of the present invention, the process temperature of step c) is at most 130 °C, preferably at most 125 °C, preferably at most 120 °C, preferably at most 115 °C, preferably at most 110 °C, preferably at most 105 °C, preferably at most 100 °C, preferably at most 95 °C, preferably at most 90 °C, preferably at most 85 °C, preferably at most 80 °C, preferably at most 75 °C.

In a preferred embodiment of the present invention, the process temperature of step c) is 80 to 130 °C, preferably 90 to 125 °C, preferably 100 to 120 °C.

According to a preferred embodiment of the present invention, the process temperature of step c) is 60 to 90°C, preferably 65 to 85 °C, preferably 70 to 80 °C.

In a preferred embodiment of the present invention, the pulp additive obtained in step d) is characterized by a Schopper-Riegler value (SR) from 10 to 95, preferably 20 to 90, preferably 30 to 85, preferably 40 to 80, preferably 50 to 75.

In a preferred embodiment of the present invention, the pulp additive is obtained in step d) as a crumb, dumb, granule, fine moss like fibre ball, plasticised fibre platelets or chips or fluff pulp.

In a preferred embodiment of the present invention, the pulp additive obtained in step d) is dried in a further step e), in particular by chamber drying, electronic wave drying, in a compact descending drier, in a sawdust drier or by floor drying.

Preferably, the pulp additive obtained in step d) is dried in a further step e) to a dry matter content of at least 35 wt.-%, preferably at least 40 wt.-%, preferably at least 50 wt.-%, preferably at least 55 wt.-%, preferably at least 60 wt.-%, preferably at least 65 wt.-%, preferably at least 70 wt.-%, preferably at least 75 wt.-%, preferably at least 80 wt.-%, preferably at least 85 wt.-%, preferably at least 90 wt.-%, preferably at least 95 wt.-% (based on the overall weight of the pulp additive).

Particularly preferred, the pulp additive obtained in step d) is dried in a further step e) to a dry matter content of at least 87 wt.-%, preferably at least 88 wt.-%, preferably at least 89 wt.-%, preferably at least 90 wt.-% (based on the overall weight of the pulp additive). It has been found that a pulp additive having a dry matter content of at least 87 wt.-% has a particularly good microbiological storage stability.

In a further preferred embodiment of the present invention, the pulp additive obtained in step d) is dried in a further step e) so as to have a bulk density of at least 0.3 g/cm ³ , preferably at least 0.35 g/cm ³ , preferably at least 0.4 g/cm ³ , preferably at least 0.45 g/cm ³ , preferably at least 0.5 g/cm ³ , preferably at least 0.55 g/cm ³ , preferably at least 0.6 g/cm ³ .

According to a preferred embodiment, the pulp additive obtained in step d) is dried in a further step e) so as to have a bulk density of at most 0.8 g/cm ³ , preferably at most 0.75 g/cm ³ , preferably at most 0.7 g/cm ³ , preferably at most 0.65 g/cm ³ , preferably at most 0.6 g/cm ³ , preferably at most 0.55 g/cm ³ , preferably at most 0.5 g/cm ³ , preferably at most 0.45 g/cm ³ , preferably at most 0.4 g/cm ³ .

Particularly preferred, the pulp additive obtained in step d) is dried in a further step e) so as to have a bulk density of 0.3 to 0.8 g/cm ³ , preferably 0.35 to 0.75 g/cm ³ , preferably 0.4 to 0.7 g/cm ³ , preferably 0.45 to 0.65 g/cm ³ .

The present invention requires in step b) the feeding of the starting material into the fibre processing apparatus according to the present invention so as to obtain a precursor, and in step c) extruding the precursor in the fibre processing apparatus to obtain the pulp additive.

Accordingly, it is a feature of the present invention that the present process is conducted in a fibre processing apparatus of the present invention.

The present invention, thus, further pertains to a fibre processing apparatus for the preparation of a pulp additive from a sugar beet starting material, wherein said apparatus comprises: at least one housing comprising at least one inlet configured to allow the feeding of the starting material, an outlet downstream of the inlet configured to allow the exit of the pulp additive, and at least one screw processor including at least one rotatable extruder shaft, preferably two extruder shafts, which screw processor is provided within the housing and provided to extend along the flow path of the starting material from the at least one inlet to the outlet, wherein the at least one extruder shaft, preferably the two shafts, comprises along its longitudinal axis at least two different processing sections including a fibre modification section and a fibre transport section, wherein the fibre transport section comprises at least one flow control element, wherein the fibre modification section comprises at least one refining element comprising a forward surface, a rearward surface and a peripheral surface, and wherein at least one of the forward surface, the rearward surface and the peripheral surface is at least partially textured.

In a preferred embodiment, the fibre modification section comprises at least one refining element comprising a forward surface, a rearward surface and a peripheral surface and wherein at least the forward or the rearward surface is at least partially textured.

In a further preferred embodiment of the present invention, the apparatus for the preparation of a pulp additive from a sugar beet starting material is particularly provided for in the de-fibering and/or defibrillation of cellulose fibres in sugar beet roots, preferably of sugar beet pulps obtained from sugar beet production. Particularly preferred, the apparatus for the preparation of a pulp additive from a sugar beet starting material is provided for the de-fibering and/or defibrillation of cellulose fibres in sugar beet starting material selected from the group consisting of pressed sugar beet pulp, NTT (Niedrig Temperatur Trocknung = low temperature drying) sugar beet pulp, HTT (Hoch Temperatur Trocknung = high temperature drying) sugar beet pulp, dried sugar beet pulp, non-melassed sugar beet pulp, dried non-melassed sugar beet pulp, and sugar beet pulp silage, preferably NTT sugar beet pulp silage.

According to the present invention, the at least one housing of the fibre processing apparatus comprises at least one inlet configured to allow the feeding of the starting material and an outlet downstream of the inlet configured to allow the exit of the pulp additive. Preferably, the at least one housing of the fibre processing apparatus comprises one inlet configured to allow the feeding of the starting material and one outlet downstream of the inlet configured to allow the exit of the pulp additive.

In a preferred embodiment, the at least one housing of the fibre processing apparatus comprises a plurality of fibre processing stages including at least one fibre modification stage and at least one fibre transport stage, wherein the processing stages are configured to define a flow path of the starting material from the at least one inlet to the outlet.

In a preferred embodiment, the fibre processing apparatus comprises an inlet configured to be functionally connected to at least one using stuffing screw, in particular at least one vertical and/or side feeding stuffing screw.

In a preferred embodiment, the fibre processing apparatus comprises an inlet which inlet is functionally connected to at least one using stuffing screw, in particular at least one vertical and/or side feeding stuffing screw.

In a particularly preferred embodiment of the present invention, the starting material, in particular the sugar beet starting material, is fed into the at least one inlet of the at least one housing of the fibre processing apparatus in a dry form and liquid is separately injected into the at least one housing to mix with the starting material.

In a particularly preferred embodiment of the present invention, the at least one housing of the fibre processing apparatus comprises at least two, preferably at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably at least 12, preferably at least 14, preferably at least 16, preferably at least 18, preferably at least 20, preferably at least 22, preferably at least 24, fibre processing stages.

According to a further preferred embodiment of the present invention, the fibre processing stages of the fibre processing apparatus include at least two, preferably at least three, preferably at least four, preferably at least five, preferably at least six, preferably at least seven, preferably at least eight, preferably at least nine, preferably at least 10, preferably at least 11, preferably at least 12, fibre modification stages.

In a preferred embodiment of the present invention, the fibre processing stages of the fibre processing apparatus include at least two, preferably at least three, preferably at least four, preferably at least five, preferably at least six, preferably at least seven, preferably at least eight, preferably at least nine, preferably at least 10, preferably at least 11, preferably at least 12, fibre transport stages.

According to a preferred embodiment of the present invention, the fibre processing stages of the fibre processing apparatus include the same number of fibre modification stages and fibre transport stages. In a preferred embodiment, the fibre processing apparatus according to the present invention, comprises n fibre modification stages and n+1 fibre transport stages, wherein n is an integer in the range of 2 to 30, preferably 4 to 25, preferably 5 to 20, preferably 6 to 18, preferably 8 to 16. Preferably, n is an integer > 2, preferably > 3, preferably > 4, preferably > 5, preferably > 6, preferably > 7, preferably > 8, preferably > 9, preferably > 10.

In a preferred embodiment of the present invention, the fibre modification stages and the fibre transport stages are arranged in an alternating manner along the flow path of the starting material from the at least one inlet to the outlet.

Preferably, the at least one fibre modification stage is a pressure neutralised fibre modification stage.

According to the present invention, the at least one extruder shaft of the at least one screw processor extending along the flow path in the processing stages comprises along its longitudinal axis at least two different processing sections including a fibre modification section and a fibre transport section. The processing sections of the at least one extruder shaft are preferably located in the functionally corresponding processing stages of the housing.

In a preferred embodiment of the present invention, the at least one extruder shaft of the at least one screw processor comprises along its longitudinal axis at least two, preferably at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably at least 12, preferably at least 14, preferably at least 16, preferably at least 18 preferably at least 20, preferably at least 22, preferably at least 24, processing sections.

Preferably, the processing sections include at least two, preferably at least three, preferably at least four, preferably at least five, preferably at least six, preferably at least seven, preferably eight, preferably at least nine, preferably at least 10, preferably at least 11, preferably at least 12, fibre modification sections.

In a preferred embodiment of the present invention, the processing sections include at least two, preferably at least three, preferably at least four, preferably at least five, preferably at least six, preferably at least seven, preferably eight, preferably at least nine, preferably at least 10, preferably at least 11, preferably at least 12, fibre transport sections. According to a preferred embodiment of the present invention, the fibre processing sections of the fibre processing apparatus include the same number of fibre modification sections and fibre transport sections.

In a preferred embodiment, the at least one extruder shaft comprises n fibre modification sections and n+1 fibre transport sections, wherein n is an integer in the range of 2 to 30, preferably 4 to 25, preferably 5 to 20, preferably 6 to 18, preferably 8 to 16. Preferably, n is an integer > 2, preferably > 3, preferably > 4, preferably > 5, preferably > 6, preferably > 7, preferably > 8, preferably > 9, preferably > 10.

In a preferred embodiment of the present invention, the fibre modification sections and the fibre transport sections are arranged on the at least one extruder shaft in an alternating manner.

Preferably, the fibre modification section is a pressure neutralised fibre modification section. Particularly preferred, all fibre modification sections are pressure neutralised fibre modification sections.

In a preferred embodiment of the present invention, the at least one extruder shaft comprises at least one pressure neutralised fibre modification section.

Preferably, the fibre modification section is a forward fibre modification section or a reverse fibre modification section.

In a further preferred embodiment of the present invention, the at least one extruder shaft comprises at least one forward fibre modification section and/or at least one reverse fibre modification section.

In a preferred embodiment of the present invention, the at least one extruder shaft comprises at least one pressure neutralised fibre modification section and at least one reverse fibre modification section.

In a preferred embodiment, the at least one extruder shaft comprises at least one bearing element between the at least one fibre modification section and the at least one fibre transport section. Particularly preferred, the at least one extruder shaft comprises a bearing element following each fibre modification section. In a further preferred embodiment of the present invention, the at least one extruder shaft comprises a bearing element following each fibre transport section. Preferably, each processing section along the at least one extruder shaft is separated from a consecutive processing section by at least one bearing.

The arrangement of bearings along the at least one extruder shaft, preferably between the at least one processing section, in particular between the at least one fibre modification section and the at least one fibre transport section, of the fibre processing apparatus advantageously stabilises the extender shaft and allows high rotations per minute (rpm) with lower friction and wear during operation.

In another preferred embodiment of the present invention, the fibre processing apparatus, in particular the at least one fibre modification section of the fibre processing apparatus, does not comprise elements in a forward- or backpressure arrangement, in particular no flow control elements and/or of the refining elements, in a forward- or backpressure arrangement. Particularly preferred, the elements, in particular the flow control elements and/or of the refining elements, of the fibre processing apparatus are mounted on the extruder shaft in a neutral pressure arrangement.

The neutral pressure arrangement of the elements, in particular the flow control elements and/or of the refining elements, leads to an extension of the fibre residence time in the processing sections of the at least one extruder shaft between inlet and outlet of the fibre processing apparatus. By using a neutral pressure arrangement of the elements, in particular of the refining elements, the forward motion of the material is solely based on pressure from feeding starting material to the inlet. In this way, the cellulose fibre-containing material, in particular the sugar beet starting material, is subjected to refinement by the refining elements in the fibre modification sections for an extended time leading to an increase in the degree of defibrillation of the cellulose fibres in comparison to the use of refining elements in a forward- or backpressure arrangement. The use of elements, in particular of flow control elements and/or of refining elements, in a neutral pressure arrangement increases the residence time of the cellulose fibres in the processing sections and associated therewith increases the extent of duration of interaction between cellulose fibres and refining elements during the progressing/defibrillation process along the flow path of the fibre processing apparatus.

According to the present invention, the at least two different processing sections arranged along the longitudinal axis of the at least one extruder shaft, preferably of the two shafts, include a fibre modification section and a fibre transport section, wherein the fibre transport section comprises at least one flow control element, wherein the fibre modification section comprises at least one refining element comprising a forward surface, a rearward surface and a peripheral surface, and wherein at least one of the forward surface, the rearward surface and the peripheral surface is at least partially textured.

Thus, the at least one refining element of the fibre modification section includes three major surfaces: a forward surface facing towards the inlet of the housing, a rearward surface facing towards the outlet of the housing and a peripheral surface facing towards the interior wall of the housing. The peripheral surface of the at least one refining element is a first surface around the periphery thereof and is spaced from the interior wall of the housing. In a preferred embodiment, the peripheral surface is substantially parallel to the interior walls of the housing. The at least one refining element further includes a forward surface and a rearward surface. The forward surface and the rearward surface are the second and third surface of the at least one refining element, respectively. The second and a third surface, in particular the forward surface and the rearward surface, are spaced apart and are substantially perpendicular to the interior walls of the housing and to the first surface or wall.

According to a preferred embodiment of the present invention, at least one of the forward surface, the rearward surface, and the peripheral surface of at least one refining element, preferably of all refining elements, is at least partially textured. The texturing of the surface of the at least one refining element has the advantage of providing extra grip of the material and thereby aiding the cutting process.

Preferably, the forward surface of at least one refining element, preferably of all refining elements, is at least partially textured. In a further preferred embodiment, the rearward surface of at least one refining element, preferably of all refining elements, is at least partially textured. Particularly preferred, the peripheral surface of at least one refining element, preferably of all refining elements, is at least partially textured.

In another preferred embodiment of the present invention, at least two surfaces selected from the forward surface, the rearward surface and the peripheral surface of the at least one refining element, preferably of all refining elements, are at least partially textured. Particularly preferred, the forward surface and the peripheral surface of the at least one refining element, preferably of all refining elements, are at least partially textured. In a further preferred embodiment, the rearward surface and the peripheral surface of the at least one refining element, preferably of all refining elements, are at least partially textured. Preferably, the forward surface and the rearward surface of the at least one refining element, preferably of all refining elements, are at least partially textured.

In a preferred embodiment of the present invention, the forward surface, the rearward surface and the peripheral surface of the at least one refining element, preferably of all refining elements, are at least partially textured.

Preferably, at least 20%, preferably at least 25%, preferably at least 30%, preferably at least 35%, preferably at least 40%, preferably at least 45%, preferably at least 50%, preferably at least 55%, preferably at least 60%, preferably at least 65%, preferably at least 70%, preferably at least 75%, preferably at least 80%, preferably at least 85%, preferably at least 90%, preferably at least 95%, preferably at least 98%, preferably 100% of the surface selected from forward surface, rearward surface and/or peripheral surface of the at least one refining element, preferably of all refining elements, is textured.

In a further preferred embodiment of the present invention, at most 95%, preferably at most 90%, preferably at most 85%, preferably at most 80%, preferably at most 75%, preferably at most 70%, preferably at most 65%, preferably at most 60%, preferably at most 55%, preferably at most 50%, preferably at most 45%, preferably at most 40%, preferably at most 35%, preferably at most 30%, preferably at most 25%, preferably at most 20%, preferably at most 15%, preferably at most 10%, preferably at most 5% of the surface selected from forward surface, rearward surface and/or peripheral surface of the at least one refining element, preferably of all refining elements, is textured.

In one embodiment of the present invention, at least one of the surfaces selected the forward surface, rearward surface and peripheral surface of the at least one refining element, preferably of all refining elements, comprises a textured portion and a relatively smooth portion, wherein the location and size of the area of texturing is selected with respect to the particular material which is to be processed and/or the size of the fibres which is to be achieved.

In a preferred embodiment of the present invention, the type and extent of texturing of the forward surface, the rearward surface, and the peripheral surface can vary between individual elements and/or between the different surfaces of the same element. In a preferred embodiment, the texturing of the forward surface, the rearward surface, and the peripheral surface can vary in pattern, frequency, depth, pitch and angle between individual elements and/or between the different surfaces of the same element. In one embodiment of the present invention, the texturing is provided as a series of serrations. In another embodiment, the texturing includes ridges, or steps along the surface.

Particularly preferred, the at least one surface of at least one refining element comprises a texturing selected from the group consisting of serrated, stepped, ridged, ribbed, toothed, grooved, pinned, spotted, pimpled and spiked formations and any combination thereof.

According to a preferred embodiment, one of the surfaces selected from forward, rearward, and peripheral surface of the at least one refining element, preferably of all refining elements, has a texturing which differs from the texture of the other two surfaces. Preferably, two surfaces selected from forward, rearward, and peripheral surface of the at least one refining element, preferably of all refining elements, have a texturing which differs from the texture of the third surface. In a further preferred embodiment of the present invention, all surfaces selected from forward, rearward, and peripheral surface of the at least one refining element, preferably of all refining elements, differ in texturing.

According to a preferred embodiment of the present invention, symmetrical or opposing texturings can be used on surfaces of paired elements, located on adjacent extruder shafts of the screw processor.

In a preferred embodiment of the present invention, the elements, in particular the refining elements, are mono-lobal, bi-lobal or tri-lobal elements or a combination thereof.

According to a further preferred embodiment, the elements, in particular the refining elements, are asymmetric elements.

In a particularly preferred embodiment of the present invention, at least one interior wall of the at least one housing of the fibre processing apparatus is at least partially textured. Preferably, the interior walls of the at least one housing of the fibre processing apparatus are completely textured. In a further preferred embodiment of the present invention the interior walls of the at least one housing of the fibre processing apparatus are at least partially textured, preferably completely textured, in the fibre modification sections in which the at least one refining element is arranged on the at least one extruder shaft.

Preferably, the texturing on the at least one interior wall of the least one housing of the fibre processing apparatus is provided as a series of serrations. In another embodiment, the texture includes ridges, or steps along the surface. Preferably, the texture includes any or any combination of serrated, stepped, ridged, ribbed, toothed, grooved, pinned, spotted, pimpled and/or spiked formations.

According to a preferred embodiment, the elements, in particular the flow control elements and/or the refining elements, have a channel which allows the same to be mounted on the extruder shaft and engagement means to allow the element to be rotated along with the extruder shaft.

In a preferred embodiment of the present invention, the distance between the radially outward surface at least one refining element and the interior wall of the housing is at most 5 mm, preferably at most 4 mm, preferably at most 3 mm, preferably at most 2 mm, preferably at most 1,5 mm, preferably at most 1 mm, preferably at most 0.9 mm, preferably at most 0.8 mm, preferably at most 0.7 mm, preferably at most 0.6 mm, preferably at most 0.5 mm, preferably at most 0.4 mm, preferably at most 0.3 mm, preferably at most 0.25 mm, preferably at most 0.2 mm.

According to a further preferred embodiment, the distance between the radially outward surface at least one refining element and the interior wall of the housing is at least 0.1 mm, preferably at least 0.15 mm, preferably at least 0.2 mm, preferably at least 0.25 mm, preferably at least 0.3 mm, preferably at least 0.35 mm, preferably at least 0.4 mm, preferably at least 0.45 mm, preferably at least 0.5 mm, preferably at least 0.6 mm, preferably at least 0.7 mm, preferably at least 0.8 mm, preferably at least 0.9 mm, preferably at least 1 mm, preferably at least 1,5 mm, preferably at least 2 mm, preferably at least 2.5 mm, preferably at least 3 mm, preferably at least 3.5 mm, preferably at least 4 mm, preferably at least 4.5 mm.

Particularly preferred, the distance between the radially outward surface at least one refining element and the interior wall of the housing is 0.1 to 5 mm, preferably 0.1 to 4.5 mm, preferably 0.1 to 4 mm, preferably 0.25 to 3 mm, preferably 0.25 to 2.5 mm, preferably 0.5 to 2 mm, preferably 0.5 to 1.5 mm.

In a preferred embodiment of the present invention, the screw processor of the fibre processing apparatus is a twin-screw processor, preferably wherein at least one refining element provided on a first shaft is arranged to intermesh and/or engage a complementary refining element provided on a second shaft of the screw processor. Preferably, one or more refining elements provided on a first shaft are arranged to intermesh and/or engage complementary refining elements provided on a second shaft of the screw processor. Particularly preferred, one or more elements provided on a first shaft are arranged inversely phased in relation to complementary elements provided on a second shaft of the screw processor. In a preferred embodiment of the present invention, one or more elements provided on a first shaft are arranged to intermesh and/or engage complementary elements provided on a second shaft of the screw processor so as to provide a orthogonal path, in particular a path of 80° to 100°, preferably 85° to 95°, most preferably 90°, for the material to be processed, in particular for the precursor, relative to the general material transport direction from the at least one inlet to the outlet when the material passes from one refining element to the abutting refining element of the at least one fibre modification section.

Particularly preferred, the material to be processed, in particular the precursor, has to pass a path from the at least one inlet to the outlet which is at least 15 times, preferably at least 16 times, preferably at least 17 times, preferably at least 18 times, preferably at least 19 times, preferably at least 20 times, preferably at least 21 time, preferably at least 22 times, preferably at least 23 times, preferably at least 24 times, preferably at least 25 times, the distance between the at least one inlet to the outlet of the fibre processing apparatus.

Preferably, the material to be processed, in particular the precursor, has to pass a path of at least 35 m, preferably at least 40 m, preferably at least 45 m, preferably at least 50 m, preferably at least 55 m, preferably at least 60 m, preferably at least 65 m, preferably at least 70 m, preferably at least 75 m, preferably at least 80 m, from the at least one inlet to the outlet of the fibre processing apparatus.

According to a preferred embodiment of the invention, the screw processor, in particular the twin- screw processor, includes at least two substantially parallel or angularly offset shafts with the elements mounted on the respective shafts and located by the shafts such that the same intermesh. In one embodiment, the intermeshing serves to create a scissor action that cuts across the material and/or splits the material along its length (via a parallel texture action). This allows the efficient shortening (if and as required) and or restructuring of the material surface but does not impair the material quality.

In a further embodiment of the present invention, more than two shafts may be provided. Preferably, the screw processor may be provided with an even number of shafts, in particular with four, six, eight, ten or more shafts. In a particularly preferred embodiment of the present invention, the shafts with elements mounted thereon are provided to intermesh with elements provided on at least one adjacent shaft. According to a preferred embodiment of the present invention, the shafts are located adjacent one another, in substantially the same plane. Typically, such an arrangement provides a substantially linear configuration of the screw processor.

In one further embodiment, a plurality of shafts may be arranged parallel to, and about, a central, longitudinal axis of the screw processor. Preferably, such an arrangement provides a substantially planetary configuration of the screw processor. In a preferred embodiment, said arrangement may be provided wherein at least four shafts are provided. Preferably, an even number of shafts are provided in the planetary configuration.

In another preferred embodiment of the present invention, the screw processor comprises at least four shafts which are arranged in a planetary configuration. A planetary configuration of shafts and associated elements advantageously permits a greater size of element relative to those in a linear configuration.

Preferably, the at least one extruder shaft includes a plurality of elements of varying sizes located thereon, and provided to intermesh with corresponding elements of varying sizes located on at least one adjacent extruder shaft provided in the screw processor.

According to a preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a diameter of at least 5 mm, preferably at least 10 mm, preferably at least 25 mm, preferably at least 50 mm, preferably at least 75 mm, preferably at least 100 mm, preferably at least 200 mm, preferably at least 300 mm, preferably at least 400 mm, preferably at least 500 mm, preferably at least 600 mm, preferably at least 700 mm, preferably at least 800 mm, preferably at least 900 mm, preferably at least 1000 mm, preferably at least 1250 mm, preferably at least 1500 mm, preferably at least 1750 mm, preferably at least 2000 mm.

In a further preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a diameter of at most 3000 mm, preferably at most 2750 mm, preferably at most 2500 mm, preferably at most 2250 mm, preferably at most 2000 mm, preferably at most 1750 mm, preferably at most 1500 mm, preferably at most 1250 mm, preferably at most 1000 mm, preferably at most 750 mm, preferably at most 500 mm, preferably at most 250 mm, preferably at most 200 mm, preferably at most 150 mm, preferably at most 100 mm, preferably at most 50 mm. In a particularly preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a diameter between 5 mm and 2500 mm, preferably between 25 mm and 2000 mm, preferably between 50 mm and 1500 mm, preferably 75 mm and 100 mm. In one embodiment of the present invention, all elements, in particular all flow control elements and/or all refining elements, have the same diameter. In another preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have different diameters. Particularly preferred, the elements, in particular the flow control elements and/or the refining elements, have a diameter in any or any combination of the following ranges: 5 mm to 100 mm; 100 mm to 300mm; 300 mm to 1500 mm; and 1500 mm to 2500 mm.

In a further preferred embodiment of the present invention, the width of the elements, in particular of the flow control elements and/or of the refining elements, can vary. Particularly preferred, the area of the peripheral surface of the elements, in particular of the flow control elements and/or of the refining elements, can vary.

In an embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have different widths. In a further preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have different the same width. Particularly preferred, all elements, in particular all flow control elements and/or all refining elements, in a grouping or cluster of elements have the same width.

Particularly preferred, the elements, in particular the flow control elements and/or the refining elements, have a width in any or any combination of the following ranges: 10 mm to 50 mm; 50 mm to 250 mm; 250 mm to 500 mm; and 500 mm to 1000 mm.

According to a preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a width of at least at least 2 mm, preferably at least 3 mm, preferably at least 4 mm, preferably at least 5 mm, preferably at least 6 mm, preferably at least 7 mm, preferably at least 8 mm, preferably at least 9 mm, preferably at least 10 mm, preferably at least 15 mm, preferably at least 20 mm, preferably at least 25 mm, preferably at least 30 mm, preferably at least 35 mm, preferably at least 40 mm, preferably at least 50 mm, preferably at least 55 mm, preferably at least 60 mm, preferably at least 65 mm, preferably at least 70 mm, preferably at least 75 mm, preferably at least 80 mm, preferably at least 85 mm, preferably at least 90 mm, preferably at least 95 mm, preferably at least 100 mm, preferably at least 150 mm, preferably at least 200 mm, preferably at least 250 mm, preferably at least 300 mm.

In a further preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a width of at most 1000 mm, preferably at most 800 mm, preferably at most 700 mm, preferably at most 600 mm, preferably at most 500 mm, preferably at most 450 mm, preferably at most 400 mm, preferably at most 350 mm, preferably at most 300 mm, preferably at most 250 mm, preferably at most 200 mm, preferably at most 150 mm, preferably at most 100 mm, preferably at most 90 mm, preferably at most 80 mm, preferably at most 75 mm, preferably at most 70 mm, preferably at most 65 mm, preferably at most 60 mm, preferably at most 55 mm, preferably at most 50 mm, preferably at most 45 mm, preferably at most 40 mm, preferably at most 35 mm, preferably at most 30 mm, preferably at most 25 mm, preferably at most 20 mm, preferably at most 15 mm, preferably at most 10 mm.

Particularly preferred, the at least one refining element, preferably all refining elements, has/have a width of at most 10 mm, preferably at most 9.5 mm, preferably at most 9 mm, preferably at most 8.5 mm, preferably at most 8 mm.

In a further preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a width between 2 mm and 1000 mm, preferably 3 mm and 500 mm, preferably 4 mm and 250 mm, preferably 5 mm to 100 mm.

In a particularly preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a width between 2 mm and 100 mm, preferably 3 mm and 75 mm, preferably 4 mm and 50 mm, preferably 5 mm to 25 mm, preferably 6 mm to 20 mm, preferably 7 mm to 15 mm, particularly preferably 8 mm to 10 mm.

According to a particularly preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, have a diameter/width ratio of >8, preferably >9, preferably >10, preferably >11, preferably >12, preferably >13, preferably >14, preferably >15, preferably >16, preferably >17, preferably >18, preferably >19, preferably >20.

Preferably, the elements, in particular the flow control elements and/or the refining elements, have a diameter/width ratio of 8 to 40, preferably 9 to 30, preferably 10 to 20, preferably 12 to 15.

The use of the thin refining elements, preferably a grouping of thin refining elements advantageously contributes to the extension of the residence time and of the total distance cellulose fibres have to pass from the at least one inlet to the outlet of the fibre processing apparatus and associated therewith increases the extent and duration of interaction between cellulose fibres and refining elements during the progressing/defibrillation process along the flow path of the fibre processing apparatus. The extension of the total distance which cellulose fibres have to pass from the at least one inlet to the outlet of the fibre processing apparatus is based on a particularly preferred configuration in which corresponding refining elements, preferably groupings of corresponding refining elements, which are located on two adjacent extruder shafts of the screw processor are arranged so that they intermesh and/or engage during operation. Particularly preferred, such arrangement includes corresponding groupings of refining elements which are located on two adjacent extruder shafts, wherein the individual refining elements of each grouping are arranged abutting and offset to each other to allow the refining elements of the grouping located on the first extruder shaft to engage with the corresponding refining elements of the grouping located on the second extruder shaft. Particularly preferred, each refining element of the corresponding intermeshing and/or engaging groupings of refining elements arranged on adjacent extruder shafts which are operated in co-rotational mode is inversely phased in relation to the respective corresponding refining element of the adjacent extruder shaft. In such configuration the cellulose fibre-containing material is required to repeatedly follow a 90° path relative to the general material transport direction from the at least one inlet to the outlet when is passes from one refining element to the abutting refining element. This effect is particularly enhanced by using thin refining elements, in particular grouping of thin refining elements, in the fibre modification sections. In a preferred embodiment, the elements, in particular the refining elements, are mono-lobal, bi-lobal or tri-lobal elements or asymmetric elements. The use of elements, in particular the refining elements, having a mono-lobal, bi-lobal, tri-lobal or asymmetric design can provide improved processing efficiency.

In one preferred embodiment of the present invention, at least some of said elements, in particular at least some of the flow control elements and/or at least some of the refining elements, are provided with a substantially circular profile. Particularly preferred, the elements, in particular the flow control elements and/or the refining elements, have a channel which is provided offset from a central axis of the elements, in particular of the flow control elements and/or the refining elements.

According to a further preferred embodiment, at least some of the elements, in particular at least some of the flow control elements and/or at least some of the refining elements, are provided in the form of one or more cog-like members. In a preferred embodiment of the present invention, at least some of the elements, in particular at least some of the flow control elements and/or at least some of the refining elements, are provided having a substantially conical shape.

In another embodiment of the present invention, at least some of the elements, in particular at least some of the flow control elements and/or at least some of the refining elements, include at least one sub-element located within a cavity, aperture or channel of the element. Preferably, the element, in particular the flow control element and/or the refining element, and the at least one sub-element are arranged rotatable about the extruder shaft, thereby providing multiple cutting / manipulating / processing points for a material as it passes therethrough.

According to a preferred embodiment, the elements, in particular the flow control elements and/or the refining elements, are formed integrally with the shaft. In an alternative embodiment, the elements, in particular the flow control elements and/or the refining elements, are formed independently and subsequently detachably mounted to the at least one extruder shaft. In a further embodiment of the present invention, some of the elements, in particular some of the flow control elements and/or some of the refining elements, are formed integrally with the shaft and some of the elements, in particular some of the flow control elements and/or some of the refining elements, are independently and subsequently detachably mounted to the at least one extruder shaft.

In a preferred embodiment, the elements, in particular the flow control elements and/or the refining elements, are provided individually on the at least one extruder shaft of the at least one screw processor.

In a further preferred embodiment of the present invention, the elements, in particular the flow control elements and/or the refining elements, are provided in groupings or clusters of elements.

Particularly preferred, all elements, in particular all refining elements and/or all flow control elements, in one grouping or cluster of elements have the same design and/or dimensions.

Preferably, the at least one fibre modification section comprises at least one grouping or cluster of refining elements.

Particularly preferred, each grouping or cluster of refining elements, forms one fibre modification section on the at least extruder shaft. In another preferred embodiment of the present invention, the at least one fibre transport section comprises at least one grouping or cluster of flow control elements.

Particularly preferred, each grouping or cluster of flow control elements, forms one fibre transport section on the at least extruder shaft.

In a preferred embodiment, the at least one extruder shaft of the at least one screw processor comprises along its longitudinal axis at least two, preferably at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably at least 12, groupings or clusters of elements, in particular of flow control elements and/or of refining elements.

Preferably, the at least one extruder shaft of the at least one screw processor comprises along its longitudinal axis 2 to 30, preferably 5 to 25, preferably 10 to 20, groupings or clusters of elements, in particular of flow control elements and/or of refining elements.

Particularly preferred, a grouping or cluster of elements, in particular flow control elements and/or refining elements, comprise a series of at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably at least 12, preferably at least 14, preferably at least 16, preferably at least 18, preferably at least 20, elements, in particular flow control elements and/or refining elements.

In another preferred embodiment, a grouping or cluster of elements, in particular flow control elements and/or refining elements, comprise a series of at most 50, preferably at most 40, preferably at most 30, preferably at most 25, preferably at most 20, preferably at most 18, preferably at most 16, preferably at most 14, preferably at most 12, preferably at most 10, preferably at most eight, preferably at most six, control elements and/or refining elements.

According to a further preferred embodiment of the present invention, a grouping or cluster of elements, in particular flow control elements and/or refining elements, comprise a series of 4 to 50, preferably 6 to 40, preferably 8 to 30, preferably 10 to 25, control elements and/or refining elements.

In a preferred embodiment of the present invention, at least two, preferably at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably all, of the elements, in particular of the flow control elements and/or of the refining elements, in a grouping or cluster of elements are arranged rotationally inline. In a further preferred embodiment of the present invention, at least two, preferably at least four, preferably at least six, preferably at least eight, preferably at least 10, preferably all, of the elements, in particular of the flow control elements and/or of the refining elements, in a grouping or cluster of elements are arranged abutting and offset to each other.

Preferably, there is provided a plurality of processing groupings or clusters along the length of the shaft assembly, wherein the groupings or clusters are separated by flow acceleration and/or restriction means so as to ensure that the material dwells at the respective groupings or clusters for a sufficient time to cause the mechanical manipulation and/or processing to occur.

In one embodiment of the present invention, the refining elements of the fibre modification section act to perform a pressure opening action on the cellulose-comprising plant material, in particular on the sugar beet starting material. Preferably, the pressure opening action is performed on the fibres of a cellulose material.

In a further embodiment, the flow control elements of the fibre transportation section are arranged on the at least one shaft to cause flow acceleration and/or restriction and are preferably a series of spiral screw elements which are suitably positioned on the at least one shaft so as to increase and/or reduce the speed of flow of the cellulose-containing plant material, in particular of the sugar beet starting material, along the flow path of the fibre processing apparatus.

In a preferred embodiment, at least one of the surfaces selected from forward surface, rearward surface and peripheral surface of the elements, in particular of the refining elements, is angled across and/or along the surface which, in one embodiment is achieved by any or any combination of milling, gear cutting, knurling or other texturizing system including an applied surface coating. This significantly increases the mechanical manipulation and/or processing work done on the source material as required.

In one embodiment of the present invention, the fibre processing apparatus allows de-fibering, defibrillation, and macro/micro/nano scale conversion of fibre in starting material, in particular sugar beet starting material, having a solid content from 3 to 95%, preferably 11 to 85%, and most preferably 25 to 75%.

According to a further preferred embodiment of the present invention, the fibre processing apparatus allows de-fibering, defibrillation, and macro/micro/nano scale conversion of fibre in starting material, in particular sugar beet starting material, having a solid content of at least 3%, preferably at least 5%, preferably at least 10%, preferably at least 15%, preferably at least 20%, preferably at least 25%, preferably at least 30%, preferably at least 35%, preferably at least 40%, preferably at least 45%, preferably at least 50%.

Preferably, the fibre processing apparatus allows de-fibering, defibrillation, and macro/micro/nano scale conversion of fibre in starting material, in particular sugar beet starting material, having a solid content of at most 95%, preferably at most 90%, preferably at most 85%, preferably at most 80%, preferably at most 75%, preferably at most 70%, preferably at most 60%, preferably at most 55%, preferably at most 50%, preferably at most 45%, preferably at most 40%, preferably at most 35%, preferably at most 30%, preferably at most 25%.

In a preferred embodiment, the arrangement of the elements is altered in order to vary the torque or specific mechanical energy of the screw processor depending on the properties of the cellulose- containing plant material, in particular the properties of the sugar beet starting material, to be processed.

In a preferred embodiment of the present invention, at least one of the elements, in particular at least one of the refining elements, is provided of a shape wherein the circumference of the elements follows the path of a substantially circular sine wave. Preferably, about the circumference of the element, in particular of the refining elements, there are provided an equal number of peaks and troughs in the surface thereof. In some embodiments, the elements, in particular the refining elements, are provided as having eight peaks and troughs.

Particularly preferred, the peripheral surface of at least one of the refining elements, preferably of all refining elements, comprises alternating peaks and troughs and/or the peripheral surface is shaped so that the circumference of the elements follows the path of a substantially circular sine wave.

According to a further preferred embodiment of the present invention, at least one of the elements, in particular at least one of the refining elements, is a blade-type element, in particular its circumference being shaped so that the circumference of the elements follows the path of a substantially circular sine wave.

Preferably, the peaks of a first element, in particular of a first refining element, on a first extruder shaft are arranged to engage and/or intermesh the troughs of a second element, in particular a second refining element, on a second extruder shaft, and vice versa. A design of the refining elements in which the peripheral surface comprises alternating peaks and troughs so that the circumference of the elements follows the path of a substantially circular sine wave is suitable to provide a particularly high compression on the cellulose fibres in the material, in particular when the peaks and troughs of two corresponding refining elements having such design are located on two adjacent extruder shafts and are arranged to intermesh and/or engage. The high mechanical manipulation and/or processing work on the cellulose-containing material is further increased by the fact that at least one of the forward surface, the rearward surface and the peripheral surface is at least partially textured. The particularly high compression of such design of the refining elements in combination with a surface texturing, preferably a texturing of the peripheral surface, provides conditions leading to a particularly high degree of defibrillation of cellulose fibres in sugar beet starting materials. This effect can further be increase by a pressure neutralised arrangement of refining elements which increases the residence time of the cellulose fibres in the processing sections and associated therewith increases the extent of duration the extent and duration of interaction between cellulose fibres and refining elements during the progressing/defibrillation process along the flow path of the fibre processing apparatus.

In a further embodiment of the present invention, two or more elements, in particular two or more refining elements, are provided adjacent and/or abutting one another along the at least one extruder shaft of the screw processor. Preferably, the adjacent and/or abutting elements, in particular refining elements, are arranged to be rotationally offset from one another. Preferably, the offset is provided to be between approximately 11.25° and 22.5°. Preferably, a similar arrangement may be provided on a second extruder shaft of the screw processor, permitting intermeshing and/or engaging of first and at least second series of offset elements, in particular offset refining elements.

In a preferred embodiment of the present invention, adjacent and/or abutting refining elements, in particular adjacent and/or abutting refining elements of a grouping or cluster of elements, are mounted on the at least one extruder shaft with a spacing between each other of at least 0.1 mm, preferably at least, preferably at least 0.2 mm, preferably at least 0.3 mm, preferably at least 0.4 mm, preferably at least 0.5 mm, preferably at least 0.6 mm, preferably at least 0.7 mm, preferably at least 0.8 mm, preferably at least 0.9 mm, preferably at least 1 mm, preferably at least 1.5 mm, preferably at least 2 mm, preferably at least 2.5 mm, preferably at least 3 mm.

In a further preferred embodiment, adjacent and/or abutting refining elements, in particular adjacent and/or abutting refining elements of a grouping or cluster of elements, are mounted on the at least one extruder shaft with a spacing between each other of at most 5 mm, preferably at most 4.5 mm, preferably at most 4 mm, preferably at most 3.5 mm, preferably at most 3 mm, preferably at most 2.5 mm, preferably at most 2 mm, preferably at most 1.5 mm, preferably at most 1 mm, preferably at most 0.75 mm, preferably at most 0.5 mm, preferably at most 0.25 mm.

Particularly preferred, adjacent and/or abutting refining elements, in particular adjacent and/or abutting refining elements of a grouping or cluster of elements, are mounted on the at least one extruder shaft with a spacing between each other of 0.1 to 5 mm, preferably 0.2 to 4 mm, preferably 0.5 to 3 mm.

According to a preferred embodiment, the “sharpness” of the peaks and troughs of the elements, in particular refining elements, is varied according to specific requirements. That is to say, the peaks may be provided to be more or less pronounced, with deeper or shallower troughs, depending on the specific needs and requirements of the apparatus, in particular depending on the properties of the of the cellulose-containing plant material, in particular of the sugar beet starting material, and/or on the desired properties of the product, in particular of the pulp additive.

According to a specific embodiment of the invention, at least some of the elements, in particular at least some of the refining elements, are tri-lobal elements. Preferably, the tri-lobal members are arranged on at least a first shaft as a series of at least two adjacent and/or abutting tri-lobal elements.

Particularly preferred, the adjacent and/or abutting tri-lobal elements are provided to be rotationally in-line with one another. In another embodiment, adjacent and/or abutting tri-lobal elements may be provided to be rotationally offset from one another. Typically, said rotational offset is provided to be approximately 60°.

In a preferred embodiment, a first grouping of abutting and/or adjacent tri-lobal elements is arranged to be rotationally in-line with one another, and at least a second grouping of abutting and/or adjacent tri-lobal elements positioned to be rotationally in-line with one another and rotationally offset from the first grouping.

According to a preferred embodiment of the present invention, the surfaces of the elements, in particular the surfaces of the flow control elements and/or refining elements, and/or the interior walls of the at least one housing of the fibre processing apparatus in which the at least one extruder shaft is located may be hardened and/or coated in order to make them more durable and extend their wear characteristics. Preferably, the surfaces may be hardened and/or coated with any of the following: tungsten carbide; tungsten carbide and cobalt matrix; tungsten carbide and nickel matrix; tungsten carbide micron and nanometer particles, and cobalt matrix; silicon carbide plating; and/or nickel silicon carbide plating.

In a preferred embodiment of the present invention, at least one refining element comprises a recess in its forward and/or rearward surface configured to receive a separator ring.

Preferably, the separator ring in a recess in the forward and/or rearward surface of the at least one refining element provides a gap between adjacent or abutting refining elements.

Particularly preferred, the separator ring in a recess in the forward and/or rearward surface of the at least one refining element provides a gap of at least 1 mm, preferably at least 1.5 mm, preferably at least 2 mm, preferably at least 2.5 mm, preferably at least 3 mm, preferably at least 3.5 mm, preferably at least 4 mm, preferably at least 4.5 mm, preferably at least 5 mm, between adjacent or abutting refining elements

The fibre processing apparatus of the present invention advantageously enables the production of a pulp additive from a sugar beet starting material, wherein cellulose fibres in the starting material are processed under controlled circumstances including fibre length and/or outer wall modification such that fibre over-shortening or outer wall damage can be controlled. The type, location, and extent of texturing on the surfaces of elements can be varied to allow for finer or rougher material de-fibering and or defibrillating and also the number, type, and arrangement of different elements can be selected depending on properties of the starting material, in particular the sugarbeet starting material, and the demands on the pulp additive to be produced. Furthermore, the materials used to manufacture the elements can be varied to be of specific grade relative to the properties of the fibres in the starting material, the desired product properties and according to industry demands i.e., hygiene, corrosion free, reaction to fibre or additive properties etc.

In another embodiment of the present invention, the at least one extruder shaft of the of the screw processor comprises along its longitudinal axis one or more drill-bit or drill type elements.

The present invention also pertains to a pulp additive obtainable, in particular obtained, by the process according to the present invention.

The pulp additive obtained by the method according to the invention proved to be economically usable in producing a wide range of paper and board products, for example absorbent papers, newsprint, printings and writing, laminating bases, packaging papers, such as fluting, liners and carton board, container, boxes, bowls, cups, or plates. Advantageously, the pulp additive obtained by the method according to the invention allows at least the partial substitution of lignocellulosic wood-based raw materials conventionally used in the production of paper and board products while maintaining or even improving the properties of the products, in particular tensile strength, burst resistance, tear resistance, and/or compression strength of the products.

In a preferred embodiment of the present invention, the pulp additive comprises micro and nano fibrillate nano cellulose (M/NFC) comprising a relatively long core of fibres with fibrils located to the core.

According to the present invention, it is possible to control of the speed of revolution of the shaft so as to achieve more, or less intense defibrillation. Establishing the best compromise between defibrillation and energy is therefore important and the provision of the appropriate elements and the configuration of the same also have a significant impact.

In a preferred embodiment of the present invention, the pulp additive is used for the preparation of a single layered, duplex, corrugated or kraft paper product. Particularly preferred, the pulp additive is used for the preparation of a packaging material. In a preferred embodiment of the present invention, the pulp additive is used for the preparation of wrapping paper, cardboard, container, boxes, bowls, cups, or plates with or without matching lids, in particular salad bowls, lunch boxes, hamburger boxes, menu trays, food boxes and soup cups with or without matching lids.

In a further aspect, the invention is directed to a packing material comprising the pulp additive according to the present invention. Preferably, the packaging material comprising the pulp additive is a kraft paper product.

Preferably, the packing material comprises at least 5 wt.-%, preferably at least 10 wt.-%, preferably at least 15 wt.-%, preferably at least 20 wt.-%, preferably at least 25 wt.-%, preferably at least 30 wt.-%, preferably at least 35 wt.-%, preferably at least 40 wt.-%, preferably at least 45 wt.-%, preferably at least 50 wt.-%, preferably at least 55 wt.-%, preferably at least 60 wt.-%, preferably at least 65 wt.-%, preferably at least 70 wt.-%, preferably at least 75 wt.-%, preferably at least 80 wt.-%, preferably at least 85 wt.-%, preferably at least 90 wt.-%, preferably at least 95 wt.-%, of the pulp additive according to the present invention. According to a preferred embodiment of the present invention, the packing material comprises at most 90 wt.-%, preferably at most 85 wt.-%, preferably at most 80 wt.-%, preferably at most 75 wt.-%, preferably at most 70 wt.-%, preferably at most 65 wt.-%, preferably at most 60 wt.-%, preferably at most 55 wt.-%, preferably at most 50 wt.-%, preferably at most 45 wt.-%, preferably at most 40 wt.-%, preferably at most 35 wt.-%, preferably at most 30 wt.-%, preferably at most 25 wt.-%, preferably at most 20 wt.-%, preferably at most 15 wt.-%, preferably at most 10 wt.-%, preferably at most 5 wt.-%, of the pulp additive according to the present invention.

In a preferred embodiment, the packing material comprises 5 to 95 wt.-%, preferably 10 to 90 wt.- %, preferably 15 to 80 wt.-%, preferably 20 to 70 wt.-%, preferably 25 to 60 wt.-%, preferably 30 to 50 wt.-%, of the pulp additive according to the present invention.

The present invention also pertains to a filter based extract comprising the pulp additive according to the present invention and to a nano gel system comprising the pulp additive according to the present invention.

In the context of the present invention, “sugar beet pulp” is understood to refer to desugared sugar beet cossettes, that means sliced sugar beets having been subjected to a sugar extracting process step.

In the context of the present invention, “NTT sugar beet pulp” is understood to mean “Niedrig Temperatur Trocknung sugar beet pulp”, which means low temperature drying sugar beet pulp, preferably pressed sugar beet pulp which has subsequently been subjected to low temperature drying. In the context of the present invention, “NTT sugar beet pulp” is thus understood to refer to a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, to a low temperature drying process so as to obtain a sugar beet pulp having a dry matter content of 30 to 55 wt.-%, preferably 35 to 50 wt.-%, preferably 40 to 47 wt.-% (based on overall weight of the material). In particular, “NTT sugar beet pulp” is a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, to a low temperature drying process which drying process uses a drying temperature from 30 to 115 °C, preferably 50 to 90 °C. Preferably, “NTT sugar beet pulp” as referred to in the context of the present invention is a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, to a belt drying process for an average residence time from 10 min to 60 min, preferably 20 min to 50 min, at atmospheric pressure, wherein the belt drying process of sugar beet pulp, preferably the pressed sugar beet pulp, is conducted at an air inlet temperature of 30 to 115 °C, preferably 50 to 90 °C, and an air outlet temperature of 20 to 105 °C, preferably 30 to 80 °C, so as to obtain a sugarbeet pulp having a dry matter content of 30 to 55 wt.-%, preferably 35 to 50 wt.-%, preferably 40 to 47 wt.-% (based on overall weight of the material).

Preferably, low temperature drying of sugar beet pulp is used to avoid carbonisation in the drying process of the sugar beet pulp. In the context of the present invention, “low temperature drying” is understood as a drying process at a temperature of at most 115 °C, preferably at most 90 °C. Particularly preferred, “low temperature drying” is understood as a drying process at a temperature from 30 to 115 °C, preferably 50 to 90 °C.

The term “HTT sugar beet pulp” is understood to mean “Hoch Temperatur Trocknung sugar beet pulp”, which means high temperature drying sugar beet pulp, preferably pressed sugar beet pulp which has subsequently been subjected to high temperature drying. In the context of the present invention, “HTT sugar beet pulp” is thus understood to refer to a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, more preferably a NTT sugar beet pulp, to a drying process, so as to obtain a sugar beet starting material having a dry matter content of 75 to 96 wt.-%, preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-%, (based on overall weight of the material). In particular, “HTT sugar beet pulp” is a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, more preferably a NTT sugar beet pulp, to a high temperature drying process which drying process uses a drying temperature from 120 to 750 °C, preferably 200 to 600 °C. Preferably, “HTT sugarbeet pulp” as referred to in the context of the present invention is a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, more preferably a NTT sugar beet pulp, to a drum drying process, wherein the drum drying process of sugar beet pulp, preferably the pressed sugar beet pulp, more preferably NTT sugar beet pulp, is conducted at a temperature of 120 to 750 °C, preferably 200 to 600 °C, so as to obtain a sugar beet starting material having a dry matter content of 75 to 96 wt.-%, preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-%, (based on overall weight of the material). Particularly preferred, the term “HTT sugar beet pulp” as used context of the present invention refers to a sugar beet pulp obtainable by subjecting a sugar beet pulp, preferably a pressed sugar beet pulp, more preferably NTT sugar beet pulp, to a drum drying process for an average residence time of 30 min to 120 min, preferably 45 min to 105 min, at atmospheric pressure, wherein the drum drying process of sugar beet pulp, preferably the pressed sugar beet pulp, more preferably NTT sugar beet pulp, is conducted at an air inlet temperature of 120 to 750 °C, preferably 200 to 600 °C, an air outlet temperature of 70 to 130 °C, preferably 80 to 110 °C, and at a pressure difference between the inlet of the drum dryer and the outlet of the drum dryer of 50 to 400 kPa, preferably 100 to 300 kPa, so as to obtain a sugar beet starting material having a dry matter content of 75 to 96 wt.-%, preferably 80 to 95 wt.-%, preferably 85 to 90 wt.-%, (based on overall weight of the material).

In the context of the present invention, “high temperature drying” is understood as a drying process at a temperature of at least 120 °C, preferably at least 160 °C, preferably at least 200 °C. Particularly preferred, “high temperature drying” is understood as a drying process at a temperature from 120 to 750 °C, preferably 200 to 600 °C.

In the context of the present invention, “non-melassed sugar beet pulp” is sugar beet pulp without the addition of molasse to the sugar beet pulp after sucrose extraction. Preferably, “non-melassed sugar beet pulp” has a saccharose content of 5 to 7 wt.-% (based on overall weight of non-melassed sugar beet pulp).

In the context of the present invention, the term “pressed sugar beet pulp” refers to a sugar beet pulp obtainable by subjecting a sugar beet pulp to a pressing process, so as to obtain a pressed sugar beet starting material having a dry matter content from 18 to 38 wt.-%, most preferably 24 to 36 wt.-% (based on overall weight of the material). In particular, “pressed sugar beet pulp” is sugar beet pulp obtainable by subjecting a sugar beet pulp preferably having a dry matter content from 10 to 16 wt.-% to a pressing process using a press, preferably a spindle press, for instance a PB 22 press from Babbini, wherein the press preferably employs a pressure gradient from the press inlet via the press centre to the press outlet. Preferably, the pressure at the inlet is set to 0,1 MPa, at the centre to 0,9 MPa and at the outlet to 0,8 MPa. Preferably, the press is operated at a torque from 900 to 1100 Nm, preferably 1000 Nm. Preferably, the press is operated with a rotational speed of the motor from 800 to 1200 rpm (rotation per minute) resulting in a rotational speed of the press spindle from 1 to 2,5 rpm.

In the context of the present invention, the term “silage” refers to pressed sugar beet pulp, preferably pressed NTT sugar beet pulp, which has been subjected to a fermentation step to the point of acidification, preferably wherein the fermentation step is preceded by a compacting step so as to remove air from the pressed sugar beet pulp prior to fermentation. Particularly preferred, “sugar beet pulp silage” is obtained by pressing sugar beet pulp, preferably NTT sugar beet pulp, to obtain silage bales which are subsequently wrapped in foil and stored for fermentation. Alternatively, in the context of the present invention “sugar beet pulp silage” may also be obtained by other silaging techniques known to a skilled person, such as by fermentation in conventional silo towers, bunker silos or in silo hoses.

In the context of the present invention, the expression “fibre processing stage” refers to a particular stage within a housing of a fibre processing apparatus in which cellulose fibres in a starting material are processed. A “processing stage” within the meaning of the present invention can include a “fibre modification stage” in which the cellulose fibres in a starting material are modified, in particular are defibrillated and/or shortened, and a “fibre transport stage” in which the cellulose fibres/the cellulose fibres-containing materials are transported along a flow path of the starting material through the housing without substantial modification of the cellulose fibres in the material. Preferably, the function of these two different processing stages of the housing is allocated thereto by the presence of corresponding processing sections on an extruder shaft located in the housing.

In the context of the present invention, a “processing section” is a spatially, structurally and functionally delimitable section along the longitudinal axis of an extruder shaft which participates in the processing of the starting material. According to the present invention, the “processing sections” along the longitudinal axis of an extruder shaft include at least one “fibre modification section” and at least one “fibre transport section”.

The term “fibre modification section” as used in the context of the present invention designates a specific spatially, structurally and functionally delimitable section along the longitudinal axis of an extruder shaft which effects modification of cellulose fibres, in particular the defibrillation and/or shortening of cellulose fibres. For this purpose, the “fibre modification section” comprises at least one refining element, preferably two or more refining elements, in particular a grouping or cluster of refining elements.

The term “fibre transport section” as used in the context of the present invention designates a specific spatially, structurally and functionally delimitable section along the longitudinal axis of an extruder shaft which effects transportation of cellulose fibres/cellulose fibres-containing materials. For this purpose, the “fibre transport section” comprises at least one flow control element, preferably two or more flow control elements, in particular a grouping or cluster of flow control elements. In the context of the present invention, the term “force feeding” refers to a feeding process of the sugar beet starting material into the fiber processing apparatus, wherein the starting material is fed under pressure into the apparatus, for instance by using stuffing screws, in particular vertical and/or side feeding stuffing screws.

The expression “pressure neutralised” as used in the context of the present invention to describe a region or an arrangement within the fibre processing apparatus in which no forward- or backpressure is exerted by the design of elements, in particular of the refining elements, on the material to be processed. A “pressure neutralised arrangement”, “pressure neutralised fibre modification stage” or “pressure neutralised fibre modification section” therefore refers to an arrangement, stage, or section in which the forward motion of the material to be processed is not caused by the elements, in particular the refining elements, of the “pressure neutralised” arrangement, stage, or section, but is preferably solely based on pressure from feeding starting material to the inlet.

In contrast thereto, the terms “forward- or backpressure” are used in the context of the present invention to describe an arrangement and/or design of elements, in particular refining elements, which causes a forward motion or a retention of the motion of the material to be processed by structural characteristics of the elements or by the arrangement of elements.

In the context of the present invention, the term “reverse” is meant to refer to a backpressure arrangement or design of elements, in particular of refining elements.

In the context of the present invention, a “precursor” is a heterogenous mixture of solid sugar beet- derived solid biomaterials in an aqueous solution which is - depending on the sugar beet starting material - either obtained by directly feeding sugar beet starting material into the fibre processing apparatus according to the present invention, by mixing the sugar beet starting material with water before, during and/or after feeding it into the fibre processing apparatus. Particularly preferred, the term “precursor” as used in the context of the present invention refers to such sugar beet starting material being composed of water, soluble and insoluble beet-derived biomaterials, once it has been fed into the fibre processing apparatus, wherein the “precursor” in the fibre processing apparatus has a particular dry matter content or has been adjusted to a particular dry matter content, such as by the addition of water. Thus, the “precursor” is a sugar beet starting material either being mixed with water or not mixed with water which has been fed into the fibre processing apparatus and is subjected to an extrusion step so as to obtain the pulp additive therefrom. Alternatively, the “precursor” according to the present invention can also be termed a “suspension”.

The term ’’suspension” as used in the context of the present invention refers to heterogenous mixture of substances in which solid matter is dispersed in a liquid phase without dissolving therein.

In the context of the present invention, the term “pulp additive” refers to a composition comprising cellulose microfibres (CMF) and/or cellulose nanofibres (CNF) obtainable by defibrillation of cellulose fibres in plant-based materials, in particular a pulp additive of the present invention is obtainable by a process of the present invention, which pulp additive preferably is suitable to be used as an additive in the preparation of paper product, in particular to at least partially substitute lignocellulosic wood-based raw materials which are conventionally used in paper pulp.

In the context of the present invention, the term “and/or” is understood to mean that all members of a group connected by the term “and/or” are represented both cumulatively with respect to each other in any combination, and alternatively with respect to each other. Exemplarily, for the expression “A, B and/or C”, the following disclosure is to be understood thereunder: i) (A or B or C), or ii) (A and B), or iii) (A and C), or iv) (B and C), or v) (A and B and C), or vi) (A and B or C), or vii) (A or B and C), or viii) (A and C or B).

In the context of the present invention, individual components or constituents of a composition or of one of its components, determined quantitatively in relative form, in particular in percentages, preferably add up to 100% by weight or molar amount of the respective composition referred to or of the composition or, if referred to, of a component thereof, unless otherwise stated.

Further preferred embodiments of the present invention are apparent from the dependent claims.

The present invention will be explained in more detail in the following examples and the accompanying figures both of which are not to be understood as limiting.

Preferred embodiments of the present invention will be described with reference to the accompanying figures, wherein:

Figures la-c illustrate embodiments of screw designs in accordance with embodiments of the invention. Figures 2a-c illustrate examples of complete extruder shaft configurations in accordance with embodiments of the invention.

Figures 3a - c illustrate pairs of mono-lobal refining elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures 4a - c illustrate mono-lobal refining elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures 5a - d illustrate further images of the mono-lobal refining elements, which can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures 6a-c illustrate a further type of refining elements and their arrangements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures 7a-c illustrate variation in the peripheral surface of a further type of refining elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figure 8 illustrates a grouping arrangement of a further type of refining element that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figure 9 illustrates a grouping of aligned tri-lobal refining elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures lOa-b illustrate groupings of tri-lobal refining elements provided along a shaft wherein adjacent or abutting refining elements are provided to be rotationally offset from one another, and which can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figures 1 la-c illustrate further detail of texturing of surfaces of elements that can be incorporated into an apparatus in accordance with embodiments of the present invention.

Figure 12 shows an arrangement of processing elements along the longitudinal axis of an extruder shaft in accordance with preferred embodiments of the present invention.

Figure 13 shows a perspective view on the exterior of a fibre processing apparatus according to the invention. Figure 14 shows a top view on the exterior of a fibre processing apparatus according to the invention.

Figures 15 illustrates the SR values of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figures 16 illustrates the tensile strength of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figures 17 illustrates the burst resistance of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figures 18 illustrates the tear resistance of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figures 19 illustrates the compression strength (SCT) of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figures 20 illustrates the air permeability of paper containing 20% pulp additives prepared from different starting materials in comparison to a control in dependency on the specific energy input during grinding.

Figure 21 illustrates the compression strength (SCT) of single layer paper samples (80 g/m ² ) containing 20% (Sample 1), 30% (Sample 2) or 40% (Sample 3) pulp additives in comparison to a control (100% pulp mixture) in dependency on the specific energy input during grinding. The single layered paper samples (80 g/m ² ) of control 2 (100% pulp mixture) and Sample 4 (30% pulp additive) further comprise 0.8% of a sizing agent.

Figure 22 illustrates the density of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls. Figures 23 illustrates the specific volume of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figures 24 illustrates the tensile strength (machine direction (MD) of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figure 25 illustrates the tensile strength (cross direction (CD) of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figures 26 illustrates the burst resistance of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figure 27 illustrates the compression strength (SCT: MD) of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figure 28 illustrates the compression strength (SCT: CD) of duplex paper samples (260 g/m ² ) containing 30% pulp additive grinded at 80 kWh/t (Sample 1), 30% pulp additive grinded at 40 kWh/t (Sample 2) or 40% pulp additive grinded at 40 kWh/t (Sample 3) in the backsheet of the duplex paper in comparison to respective controls.

Figures 29 illustrates the burst resistance of corrugated base paper samples containing 30% pulp additive in comparison to conventional corrugated base paper samples (control 1) and 30 % miscanthus pulp (unbleached) (control 2). Figure 30 illustrates the compression strength (SCT: CD) of corrugated base paper samples containing 30% pulp additive in comparison to conventional corrugated base paper samples (control 1) and 30 % miscanthus pulp (unbleached) (control 2).

Figure 31 illustrates the specific volume of corrugated base paper samples containing 30% pulp additive in comparison to conventional corrugated base paper samples (control 1) and 30 % miscanthus pulp (unbleached) (control 2).

Different examples of groupings of refining elements which can be used in complete screws are shown with reference to Figures la-c. In Figure la there is shown a series of refining element groupings 801 which are separated by flow control elements 803 in order to control the flow of the substance along the screw. In Figure lb there is shown refining element groupings 801 which are separated by a combination of flow control elements 803. In Figure 1c there is illustrated the combination of flow control elements 803 as in Figure lb and in this case there is provided a first grouping of refining elements 805 which are provided to allow for the forwarding of the material along the screw using textured elements, a second grouping of refining elements 807 which are flow neutral and a third grouping of refining elements 809 which are provided to allow for a reverse or backpressure arrangement of the textured elements. Figure Id illustrates a manner in which the elements 901 can be provided selectively located in the housing 903 of the apparatus and located along a shaft 905. The elements can be positioned in a number of different ways with respect to the housing and each other so as to provide the required defibrillating and movement effect on the material which is introduced into and moved along the housing 903. For example, the elements may be provided in an in-line arrangement as shown in Figure ld(i) and (ii) or in a stepped arrangement.

Figures 2a - 2c illustrate variations in the combinations of elements which can be selectively positioned along the shaft with respect to the flow of material along the housing in the direction of arrow 911. In Figure 2a, the arrangement illustrated is selected to be used in order to achieve complete defibrillation of short fibres. In Figure 2b the screw design and element selection is with respect to the achievement of complete defibrillation of long fibres. In Figure 2c the elements selection for the screw configuration is directed to achieving the complete defibrillation of short fibres along with the added provision of side feed capabilities 913.

Thus, these examples of screws with elements in configurations in accordance with the invention illustrate the manner in which the elements types and locations can be selected to provide specific screw configurations for the defibrillation of specific materials and thereby allow a “bespoke” screw design to be achieved.

When designing the same, reference is made to the type of fibres which are required to be formed, the targeted binding power and/or the final end product properties which are required.

With regard to the fibre types then for new, industrially processed, cellulose from hard/soft wood, field and other harvested plants these fibres tend to be more robust and longer than other forms of fibres discussed below and can therefore be used to provide high quality, pure (normally lignin/hemi-cellulose free) fibre for industrial and consumer paper- and board-based products. Such fibre requires that the screw profile must contain a substantial amount of textured elements which are graded from coarse to fine. These elements can then be arranged in patterns that respond adequately to non-pre-treated or to pre-prepared fibre. Pre-treatment and/or early stage in-line treatment is preferably carried out in order to soften the cellulose cell walls (weaken the fibril bonds to core fibre) which may, in one embodiment use steaming, typically with differential pressure. Pre-treatment is useful to preserve intrinsic fibre structure (reduce debris) and to save processing energy.

The figures show, by way of example, the interaction between elements that may be located on a pair of adjacent shafts of a screw assembly. However, in practice, a screw assembly may be provided having a plurality of shafts, for example, having 4, 6, 8, 10 or more shafts. The elements provided on each shaft will then be provided to intermesh with corresponding elements on adjacent shafts, to form the screw processor assembly. The shafts may be provided adjacent one another and substantially in the same plane, forming effectively a linear configuration of shafts, when viewing them front on. Alternative configurations are also possible, and envisaged in the present invention. For example, the shafts may be arranged parallel to, and located about, a central longitudinal axis of the screw processor. This provides the shafts in a planetary configuration. Once again, corresponding elements of adjacent shafts may intermesh with one another, and so, in order for the planetary configuration to function properly, an even number of shafts are required. This requirement is not as vital when providing the screw processor assembly in a linear configuration.

Figures 3a - c illustrate refining elements having perpendicular faces 1107, 1109 provided with texturing. In the embodiments shown in Figures 3a - c, a series of rib members 1121 are provided on the perpendicular faces 1107, which extend radially from the bore 1103 to the periphery of the surface 1107. To further enhance the profile of the rib members 1121, a series of troughs 1123 may be located between adjacent rib members 1121.

Figures 4a - c illustrate further examples of texturing which may be provided on the perpendicular faces 1107, 1109 of the screw element 1101. For example, as shown in Figure 4a, a series of formations in the form of spots, pimples, recesses 1125 and/or the like may be provided on the faces 1107, 1009. Figure 4b illustrates the provision of a series of ribs or serrations 1127, wherein the ribs or serrations 1127 are located parallel to one another along a length of the perpendicular face 1107, 1109. In a further embodiment, shown in Figure 4c, the serrations 1129 may be provided to extend radially about the bore 1103, to the periphery of the face 1107, 1109.

Figures 5a - d illustrate further images of refining element 1101, firstly providing a guide to the actual size of the elements in Figure 5a. Figure 5b illustrates the element 1101 wherein a separator ring 1135 may be provided, which can be inserted into a recess 1137 in the perpendicular face 1107 around the periphery of the bore 1103. The ring 1135 can be located within the recess 1137 and this allows the gap or width between adjacent elements to be adjusted according to the type of fibre or work required. For example, separator rings 1137 of varying thicknesses may be provided, allowing for gaps of varying sizes. The ring 1135 is shown in situ on an element 1101 in Figure 5c.

Further, the width of the elements generally, and in particular as shown in Figure 5d in relation to the elements 1101 can also be varied. Creating proportionally wider elements 1101, for example, serves to create more pressure/work per rotation, in particular in a reverse screw configuration. Side grooves/serrations 1111 located on the parallel surface 1105 are provided extending in a single direction. Providing these with deeper, flatter grooves between the serrations 1111 serves to cheapen the overall production of the elements 1101 and increase the longevity of that surface, as the edges do not blunt so easily as with the more shallow and frequent grooves.

The elements of the present invention are preferably formed from high abrasion-resistant steel, in order to maximise lifetime and provide longer wear.

Figures 6a-c illustrate a further type of refining element 2201 and their arrangements along a shaft of the screw processor. The refining elements 2201 are provided of a shape wherein the circumference of the refining elements 2201 follow the path of a substantially circular sine wave. That is to say, about the circumference of the refining element 2201 there are provided an equal number of peaks 2203 and troughs 2205 in the surface thereof. In the figures shown, the refining elements 2201 have eight peaks 2203 and eight troughs 2205, although it will be understood that this number can be varied depending on the particular requirements of the apparatus. The refining elements 2201 may be provided on first and second parallel screws and arranged to engage or intermesh one another in a complementary fashion, such that the peaks 2203 of a first refining element 2201 on a first shaft are arranged to engage and/or intermesh the troughs 2205’ of a second refining element 2201’ on a second shaft, and vice versa. Typically, two or more refining elements 2201 are provided adjacent and/or abutting one another along a shaft or screw of the screw processor, and are arranged to be rotationally offset from one another. Typically, said offset is provided to be between approximately 11.25° and 22.5°. A similar such arrangement can then be provided on a second shaft or screw, permitting intermeshing and/or engaging of first and at least second series of offset refining elements 2201 and 2201’.

Figure 7a illustrate how the peripheral surface 2207 of the refining element 2201 about its circumference is also provided to be textured. This is shown also in Figure 7c. Further, Figure 7b illustrates how the “sharpness” of the peaks 2203 and troughs 2205 of the elements 2201 may be varied according to specific requirements. That is to say, the peaks may be provided to be more or less pronounced, with shallower 2207a or deeper 2207b troughs, depending on the specific needs and requirements of the apparatus.

In further embodiments, as shown in Figure 8, groupings of refining elements 2201 may be provided, rotationally inline, with an abutting group subsequently offset. The two groups are then arranged to intermesh / engage with similarly arranged groups of refining elements 2201’ on a second shaft. Such arrangement ensure that the fibres can be trapped in the troughs 2205 and compressed between opposing or intermeshing elements and/or between the peaks 2203 and the interior of the extruder barrel walls (not shown). At least part of the exterior surface of the elements of the present invention are provided to be textured.

Figure 9 illustrates a grouping of aligned tri-lobal refining elements 2501, wherein the peripheral surface 2503 about the periphery of those elements is provided to be textured. Tri-lobal elements are already known, however, no such elements are known in the art which are tailored to the requirements of defibrillating fibres and having textures or texturing provided on any of the external surfaces thereof - known versions all have completely smooth surfaces. Providing textured surfaces has specific advantages: i. Compression areas are smaller than with the open side of ‘cam’ type elements, therefore increasing fibre manipulation potential. Therefore, in contrast to the current smooth outer surfaces of current Tri-Lobals, textured surfaces (of various types) can substantially multiply the fibre defibrillation effect on the fibres themselves. ii. Individual element production as opposed to multiple blocks (most common) allows for specific rotation of the elements to create configurations that either express, hold or retain the fibre mass depending on the fibre fibrillation and type required.

In some embodiments of the invention and as shown in Figures lOa-b, groupings of tri-lobal refining elements 2501 may be provided along a shaft wherein adjacent or abutting refining elements 2501 are provided to be rotationally offset from one another. Since the elements are tri- lobal, the preferred angle of offset is approximately 60° as shown in the figures. Further, where two parallel shafts are provided, i.e., in the form of a twin screw, the grouping of offset refining elements 2501 on a first shaft are arranged to intermesh with a complementary grouping of similarly offset refining elements 2501’ on a second shaft. The exterior surface of such refining elements, about the periphery of the same are provided to be textured and can be done so in a number of ways, such as in the form of serrations, ridges, or steps along the surface, and shown in more detail in Figures 1 la-c. In some embodiments, the either or both of forward or rearward faces of the tri-lobal refining elements 2501 may be provided to be at least partially textured.

Figure 12 shows a particularly preferred arrangement of processing sections 10, 20 along the longitudinal axis of an extruder shaft 100 of a screw processor 1 in the apparatus according to the present invention. The arrangement shown in Figure 12 includes a total of 12 groupings of 12 refining elements 2 having a textured peripheral surface, wherein each of the groupings of refining elements 2 constitutes a fibre modification section 10, 10’, 10”, 10’”. The arrangement further includes a total of 13 groupings of flow control elements, wherein each of the groupings of flow control elements constitutes a fibre transport section 20, 20’, 20”, 20’”. The 12 fibre modification sections and the 13 fibre transport sections are mounted on the extruder shaft 100 of the screw processor 1 in an alternating manner. Figure 12 further provides an enlarged view of a fibre modification section 10 from which it is apparent that the individual abutting mono-lobal refining elements 2 are arranged rotationally offset from each other by 180° such that every second refining element 2.1, 2.2 of each grouping is arranged in line. This means that the abutting mono-lobal refining elements 2 in the grouping are in each case inversely phased with respect to the abutting refining elements 2 (see also Figure Id). In some embodiments of the present invention, a second shaft with the same arrangement of processing sections 10, 20 along its longitudinal axis is provided in the screw processor 1, wherein the first and second shafts are arranged with respect to each other such that the refining elements 2 in the groupings of one shaft intermesh and/or engage complementary refining elements 2 in the grouping provided on the other shaft of the screw processor 1 (not shown).

Examples:

Example 1: Preparation of a pulp additive from high-temperature dried (HTT) sugar beet pulp

HTT sugar beet pulp having a dry matter content of about 89 wt.-% (based on the overall weight of the HTT sugar beet pulp) obtained by high-temperature drying of NTT sugar beet pulp was used as sugar beet starting material.

The dry matter content of the HTT sugar beet pulp was adjusted to 55 wt.-% by the addition of water and fed into the fibre processing apparatus by force feeding using a feeding screw so as to obtain a precursor. From the extruder feeding section, the material was subject to a build-up of pressure via pitched transport screws. The fibre processing apparatus used for the processing of the HTT sugar beet pulp comprised a screw processor including two rotatable extruder shafts each having an alternating arrangement of fibre modification sections and fibre transport sections as depicted in Figure 12. Each of the two extruder shafts comprised a total of 12 pressure neutralised fibre modification sections and 13 fibre transport sections, wherein the fibre transport sections comprised flow control elements, and wherein the fibre modification sections comprised groupings of 12 mono-lobal refining elements having a textured peripheral surface. The texturing on the peripheral surface of the refining elements increases the grip and the mechanical force exerted on the cellulose fibre-containing material. The extruder shafts were operating in co-rotating mode and were arranged with respect to each other so that refining elements provided on the first shaft engage respective complementary refining elements provided on the second shaft of the screw processor, thereby creating a 90° travel path for the material with respect to the general material transport direction. The extruder shafts were balanced by bearing elements between the fibre modification sections and fibre transport sections to avoid excessive wear on the wall of the housing and on interacting refining elements located on the adjacent shafts. The pulp additive obtained from the outlet of the fibre processing apparatus had the consistency of fine granules or clumps having a dry matter content of 60-65 wt.-% (based on the overall weight of the pulp additive).

Example 2: Preparation of a pulp additive from low-temperature dried (NTT) sugar beet pulp

NTT sugar beet pulp having a dry matter content of about 43 wt.-% (based on the overall weight of the NTT sugar beet pulp) obtained by low-temperature drying of pressed sugar beet pulp was used as sugar beet starting material.

The NTT starting material having a malleable consistency was fed into the fibre processing apparatus by force feeding using a feeding screw. Processing in the fibre processing apparatus was performed similar as described in Example 1 with the exception that for the refinement of the NTT material additionally reverse fibre modifications sections each comprising at least one grouping of refining elements, which thus form a backpressure arrangement of refining elements were mounted on the two extruder shafts to retain the material in the respective fibre modification sections to ensure efficient defibrillation and size reduction of cellulose fibres. The refining elements were also characterized by a having a texturing on their peripheral surface to increase the grip and the mechanical force exerted on the cellulose fibre-containing material and the extruder shafts were balanced using bearing elements between the fibre modification sections and fibre transport sections.

The pulp additive derived from processing of the NTT sugar beet pulp starting material had the clumpy consistency with a dry matter content of 45-55 wt.-% (based on the overall weight of the pulp additive).

Example 3: Preparation of a pulp additive from pressed sugar beet pulp

Desugared sugar beet cossets from sugar production were pressed to obtain pressed sugar beet pulp having a dry matter content of about 32 wt.-% (based on the overall weight of the pressed sugar beet pulp).

The pressed sugar beet pulp starting material also showed a malleable consistency and was treated as described in Example 2 to finally yield a clumpy pulp additive having a dry matter content of 35-40 wt.-% (based on the overall weight of the pulp additive). Example 4: Preparation of a pulp additive from sugar beet pulp silage

Pressed sugar beet pulp was further pressed to silage bales which were subsequently wrapped in foil and subjected to fermentation. The resulting sugar beet pulp silage having a dry matter content of about 30 wt.-% (based on the overall weight of the sugar beet pulp silage) was used a sugar beet starting material.

Sugar beet pulp silage fed into the fibre processing apparatus had a wet and sticky consistency but an overall weaker material structure due to the silage process than other sugar beet starting materials. The processing of sugar beet pulp silage was conducted similar as for NTT sugar beet pulp (Example 2) and pressed sugar beet pulp (Example 3) except for using an increased force during feeding due to the wet and sticky consistency and by additionally using substantial backpressure and optionally filters in the fibre processing sections.

Depending on whether filters were used during extrusion or not, two different products could be obtained: semi fibrillated fibre (unfiltered) and/or highly fibrillated fibre (filtered).

The filtered silage/high wet content material is advantageous in that it obviates or at least substantially reduces the necessity of any further paper industry-related conditioning (refining/de- flaking) steps. The end result is a hybrid micro/nano fibre - near gel like substance.

Example 5: Microbiological storage stability of pulp additives

Pulp additive prepared as described in Example 1 and non-melassed sugar beet cossettes after HTT (high temperature drying) were inoculated with mould spores and moistened to different dry matter contents. Subsequently, the samples were incubated in airtightly sealed bags for a period of 2 month at a temperature of 30 °C so as to provide optimal growth conditions for the mould. The growth was investigated on a weekly basis macroscopically and partly also microscopically. Experiments were performed in duplicates.

Sample 1 : Pulp additive according to the present invention (untreated) (obtained from HTT (high temperature drying) sugar beet pulp)

Sample 2: Pulp additive according to the present invention (disintegrated; Retsch-mill and 1 mm sieve) (obtained from HTT (high temperature drying) sugar beet pulp)

Sample 3 : non-melassed sugar beet cossettes after HTT (high temperature drying) The table shows the lowest average dry matter content of the samples which did not show mould growth after the 2 months-incubation period.

It could be observed that the finely grinded pulp additive of Sample 2 seems to have the best microbiological storage stability. It could the large particles in the untreated pulp additive of Sample 1 are primarily moistened on their surface so as to build up a moisture gradient from the surface to the core of the particles which possibly promotes mould growth. The mould primarily grew on single coarse particles. The grinded particles of Sample 2 showed a more homogenous moisture distribution with no particularly wet regions.

In can be concluded that the best microbiological storage stability can be obtained by drying pulp additive to a dry matter content of at least 87 wt.-%.

Example 6: Use of pulp additives for the preparation of different test paper products

The pulp additives used in Examples 6A to D were produced from high-temperature dried (HTT) or low-temperature dried (NTT) sugar beet pulp as sugar beet starting materials as described in Examples 1 and 2.

Example 6A Grinding of pulp material under proportional additional of pulp additive according to the present invention.

1. Method

Grinding was carried out in circuit operation mode. The pulp was provided in a vat. A circuit through the vat and a refiner to achieve a defined specific edge load (SEL) was established. Samples were taken after a defined specific input of energy (40, 80, 120 and 140 kWh/t). Batch size was 6,000 g atro / 150 L (4% SD). 100% UPM Euca pulp served as control. Sample 1 contained 80 % UPM Euca pulp and 20 % of a pulp additive according to the present invention (“wet sample”) (based on dry weight of the sample). Sample 2 was composed of 80 % UPM Euca pulp and 20 % of a pulp additive according to the present invention (HTT - high temperature drying) (based on dry weight of the sample) and Sample 3 contained 80 % UPM Euca pulp and 20 % of a pulp additive according to the present invention (NTT - low temperature drying) (based on dry weight of the sample).

2. Results

2.1 Schopper Riegel (SR) -value

The addition of the pulp additive in an amount of 20 % in Samples 1, 2 and 3 resulted in an increase (over control) in the SR-value already in the unrefined state. The SR-value further increased in these samples during grinding which is due to grinding of the constituent in the pulp additive but also caused by more intense grinding of the 80 % UPM Euca pulp in comparison to the control (see Figure 15).

2.2 Tensile strength

Under comparable specific energy input the same level of tensile strength can be achieved for Samples 1, 2, and 3 as for the control at the expense of a higher SR-value (see Figure 16).

2.3 Burst resistance

Sample 2 was found to show a comparable burst resistance as the control (see Figure 17).

2.4 Tear resistance

The level of tear resistance of the control cannot be observed for Samples 1, 2 and 3 as a result of the shorter fibre length in the three Samples (see Figure 18).

2.5 Compression strength / short span compression test (SCT)

All samples show a high compression strength which is at least comparable to the control (see Figure 19).

2.6 Air permeability

In comparison to the control, Samples 1, 2, and 3 were less permeable to air (see Figure 20). Example 6B Preparation of single layer paper

1. Method

UPM Euca pulp (75%) was used as short-fibre pulp and Stendal ECF (25%) was used as long- fibre pulp of the pulp mixture. Pulp additive according to the present invention was used in amounts of 20 %, 30 %, and 40 %. As further additives 0.5% of pulp starch (Cargill C*Bond HR 35844) and optionally 0.8% sizing agent (Solenis, Aquapel F220) were used.

Grinding was carried out in circuit operation mode. The pulp was provided in a vat. A circuit through the vat and a refiner to achieve a defined specific edge load (SEL) was established. Grinding was conducted with 80 kWh/t input of specific energy. Batch size was 12,000 g atro / 300 L (4% SD).

The different single layer paper samples (100 g/m ² ) were composed as follows:

Control sample: 100% pulp mixture; Sample 1 : 80% pulp mixture, 20% pulp additive, such as specified in Example 5 (Sample 2, disintegrated); Sample 2: 70% pulp mixture, 30% pulp additive, such as specified in Example 5 (Sample 2, disintegrated); Sample 3: 60% pulp mixture, 40% pulp additive, such as specified in Example 5 (Sample 2, disintegrated).

In addition, two further single layer paper samples (80 g/m ² ) were prepared with 0.8 % sizing agent:

Control sample 2: 100% pulp mixture; Sample 4: 70% pulp mixture, 30% pulp additive, such as specified in Example 5 (Sample 2, disintegrated).

2. Results

The experiments showed the general suitability of pulp additives according to the present invention in different amounts for use in the preparation of single layer paper. All papers showed a homogeneous distribution of the pulp additive, wherein the pulp additive was partially visible in the form of small particles. With increasing amount of pulp additive, also the average fibre length, the SR value, the water retention capacity, and the density of the papers increased. All samples comprising the pulp additive according to the present invention were characterized by an increased cross directional compression strength in SCT in comparison to the controls (see Figure 21).

Example 6C Preparation of duplex paper 1. Method

UPM Euca pulp (50%) was used as short-fibre pulp and Stendal ECF (50%) was used as long- fibre pulp of the pulp mixture. Pulp additive according to the present invention was used in amounts of 30 %, and 40 %. As further additive 1.0% of pulp starch (Cargill C*Bond HR 35844) was used.

Grinding was carried out in circuit operation mode. The pulp was provided in a vat. A circuit through the vat and a refiner to achieve a defined specific edge load (SEL) was established. Grinding was conducted with 40 and 80 kWh/t input of specific energy. Batch size was 12,000 g atro / 300 L (4% SD).

The different duplex paper samples (260 g/m ² ) were composed of 145 g/m ² backsheet (comprising different amounts of the pulp additive according to the present invention), 85 g/m ² topsheet (100% pulp mixture), and 30 g/m ² coating application. The samples were as follows:

Control 1 : 100 % pulp mixture in the topsheet and backsheet (grinded at 80 kWh/t)

Control 2: 100 % pulp mixture in the topsheet and backsheet (grinded at 40 kWh/t)

Sample 1 : backsheet: 70% pulp mixture, 30% pulp additive, such as specified in Example 5

(Sample 2, disintegrated) (grinded at 80 kWh/t), topsheet 100% pulp mixture.

Sample 2: backsheet: 70% pulp mixture, 30% pulp additive, such as specified in Example 5 (Sample 2, disintegrated) (grinded at 40 kWh/t), topsheet 100% pulp mixture.

Sample 3 : backsheet: 60% pulp mixture, 40% pulp additive, such as specified in Example 5 (Sample 2, disintegrated) (grinded at 40 kWh/t), topsheet 100% pulp mixture.

2. Results

It could be observed that the SR value increases by using the pulp additive according to the present invention for the backsheet of duplex papers thereby impeding dewaterability of the pulp mixture suspension. These effects could be compensated by reducing the specific energy impact during grinding from 80 kWh/t to 40 kWh/t. Density and specific volume of the paper in Samples was comparable to the control (see Figures 22 and 23). Tensile strength (machine direction (MD): Figure 24 and cross direction (CD): Figure 25), burst resistance (see Figure 26), and compression strength (SCT) were at the same level as for the control or even considerably outperformed the control (machine direction (MD): Figure 27 and cross direction (CD): Figure 28). Tear resistance was decreased in comparison to the control due to the shorter average fibre length of the pulp additive.

Example 6D Preparation of corrugated base paper

1. Method

Pulp additive, such as specified in Example 5 (Sample 2, disintegrated) according to the present invention was used in an amount of 30 % for the preparation of corrugated base paper. 1.0% of pulp starch (Cargill C*Bond HR 35844) was used as further additive. 100% conventional corrugated base paper was used as control 1. A further comparison was made to a mixture of 70% conventional corrugated base paper and 30 % miscanthus pulp (unbleached) as control 2. The papers were additionally coated with surface starch (Cargill C*Film 07312, modified starch)

2. Results

The use of pulp additive according to the present invention proved to be technologically suitable for the preparation of corrugated base paper. The pulp additive was homogeneously distributed in the paper and was partially visible in the form of small particles. Employing the pulp additive according to the present invention in an amount of 30% resulted in maintenance of burst resistance in comparison to the control 1 (see Figure 29) and even improved compression strength (SCT CD) (see Figure 30) despite a reduced volume (see Figure 31). The level of the paper strength properties was improved in comparison to control 2 (70% conventional corrugated base paper and 30 % miscanthus pulp) (see Figures 29-31).