Field of the invention

The present invention relates to a method for producing polymer articles, such as acoustics panels and shock pads, using reclaimed fiber material for example from an artificial turf material.

Background

Synthetic turf has been used for many years as surfaces for football, baseball and soccer fields. In recent years it has been used in other applications where an alternative to natural grass is desired. These applications include at least playgrounds, residential and commercial lawns and other landscaping, paths, paintball fields, tennis courts, putting greens, dog runs etc.

Typically, synthetic turf includes a grass-like fabric having a backing and a plurality of upstanding ribbons, also called face fibers, resembling grass. Many synthetic turf products also include an infill material dispersed among the upstanding ribbons, which may consist of sand, tire rubber crumb, or other particulates, either singularly or in combination with each other. The infill material simulates the soil in natural turf, acts as a ballast, and/or contributes to the physical properties of the turf, such as resiliency, that make the turf suitable for a particular use.

Synthetic turf has a limited life span, depending on the construction of the turf, the application for which it is used, weathering and how the turf is maintained.

As an example, a typical synthetic turf for use as an athletic field may have a useful life of from about 8 to 15 years. A large amount of synthetic turf is currently being used in hundreds of athletic fields and in other applications.

Disposing of the turf is very expensive due to the composition of materials ranging from recycled rubber, sand to plastic. To avoid sending the turf to landfills at a substantial cost, recycling and reusing all or portions of the synthetic turf has been explored option over recent years to reduce costs. EP xx to the same applicant discloses a method for providing the individual components of the artificial turf

For example, WO2019/195299 proposes to recycle artificial turf material by producing a shock pad made from a binder material and a reclaimed turf material which does not require separation of the reclaimed material. This may be a cost-effective way to recycle reclaimed turf material, but the shock pad is a mixed material product which may not realize the potential value of the individual components of the reclaimed turf material and which shock pad itself complicates its subsequent upcy- cling due to its mixed composition.

In more recent years, methods to recover the individual components of artificial turf have been explored to be able to upcycle and reuse and the individual components to greater extend. Such methods are described in EP2862688A1, EP3792027A1, where the individual components of the artificial turf are recovered at high purity.

The aim of the present invention is to provide a process and products where individual components an artificial turf are utilized in a sustainable way, providing pure products with improved sustainability end-of-life.

Summary

In view of the above, an object of the present invention is to provide a method for producing a polymer article from reclaimed fiber, such as a grass fiber, from an artificial material, such as a turf material, such that the polymer article in turn is made of pure materials such that also the upcycled product provides a sustainable end-of-life. The invention thus provides ways to upcycle the reclaimed artificial turf material into products which themselves are advantageous in terms recyclability.

Accordingly, the invention provides a method for producing a polymer article, said method comprising the steps of: a. providing a texturizing portion (tp) comprising a reclaimed fiber material originating from an artificial material said reclaimed polymeric fiber having a melting point T _M tp, b. providing a binding portion (bp) in the form of a fiber material comprising at least two polymer components, wherein a first polymer component (bpl) has a melting point TMbpl and a second polymer component (bp2) has a melting point TMbp2, preferably the melting point of the first polymer component TMbpl is substantially the same as the melting point of the texturizing portion TMtp, c. mixing the texturizing portion and the binding portion in a confined space using air to obtain a mixture, d. dosing the mixture and shaping the mixture into an article having a desired shape e. heating the shaped mixture, preferably under mechanical pressure, to a processing temperature TH, wherein the processing temperature, TH, is greater than or equal to TMtp and TMbpl and TH is less than TMbp2, f. allowing the shaped, optionally compressed, and heated article to solidify to obtain the polymer article.

By selecting this processing temperature TH the texturizing portion and the first polymer component at least partially melt, while the second polymer components remains solid. This has been found to provide a polymer article having properties suitable making it suitable for use as for example shock pads and acoustics panels as will be described in greater detail below.

Additionally, selecting the relationship of melting points and processing temperatures according to the invention, has been found to reduce the proneness of the polymer article to shrink during its manufacture. Shrinkage of the polymer article, may lead to difficulties in reaching the target properties for a specific use of the polymer article, e.g. density, size, shock absorption and sound absorption.

In preferred embodiments the reclaimed fiber material is grass fiberfrom an artificial turf. Hence, a waste product of a substantial magnitude will be usable for new usable products.

The fiber material should have a high purity in order for the polymer article in itself to be sustainable at end of life. Hence, in a preferred embodiment the texturizing portion essentially consists of reclaimed artificial grass fibre, preferably made from polyolefins, more preferably substantially comprising PE. Suitably, the texturizing portion is reclaimed artificial grass fibre, comprising PE and PP fibers, where the PE fibers constitute the majority by mass of the texturizing portion, such as 80 % or 80 to 95 % by mass of the texturizing portion.

The artificial grass fibre has in preferred embodiments been obtained by a method comprising the following steps: i) downsizing a synthetic turf product into a downsized turf material; ii) separating the downsized turf material by sieving into at least a first fraction substantially comprising a mixture of backing material and additional components and a second fraction substantially comprising grass fiber components; iii) separating the second fraction obtained in step ii) by specific gravity and size by providing an airflow directed upwards in a separator configured to cause a swirling motion whereby the lighter fraction is entrained upwards in the air flow and the heavy fraction is allowed to fall downwards; where the lighter fraction substantially comprises grass fiber components, and the heavy fraction substantially comprises a mixture of backing material and additional components; and iv) collecting the light fraction obtained in step v) as reclaimed artificial grass fibre.

This method provides the grass fiber component in a purity of more than 95, 96, 97, 98, 99 or approximately 100 % w/w. In particular, the grass fiber is free of lower quality polymers and fine sand and rubber particles.

Turf products often comprise components of different colours, hence the resulting fractions may be evaluated visually for assessment of purity. Purity of e.g. rubber and grass fiber may be evaluated using standard tests in the art such as D5603 and E1131-08 from ASTM International for testing the purity of the rubber and plastics.

Such a method for obtaining artificial grass fibre may further comprises the steps of

- separating the first fraction obtained in step (ii) by specific gravity using air to provide a low-density fraction substantially comprising backing material and a high- density fraction substantially comprising additional components; and - collecting the low-density fraction.

In order to obtain good bonding where the grass fiber component is made of a polyolefin, preferably a PE, the first component and/or second component of the binding portion is/are (a) polyolefin(s), more preferably the first component is a polyethylene (PE) and the second component is a polypropylene (PP). In another preferred embodiment, the texturizing portion comprises PP, while the first and second polymer components are different types PP.

It is contemplated that the binding portion may comprise a flame retardant depending on the intended end application of the polymer article.

Tests showed that for optimal effect of the resulting product it is preferred that the mixture obtained in step c. comprises or consists essentially of at least 25 % w/w of the binding portion, preferably 25 to 45 % or 30 to 40%, based on the sum of binding portion and texturizing portion by mass. The proportion of binder to texturizer is a balance. The main aim is to utilize the highest possible amount of recycled grass fiber without compromising the adherence and performance of the resulting polymer article. Tests were made to see how low it was possible to go in terms of added binding portion. These tests showed that it was necessary to add at least 25% w/w in order to obtain both a proper coherence of the article but also to be able to compress to a desired area density depending on intended application of the resulting article. Consequently, the mixture of step c. comprises 75 % w/w or less of the texturizing portion, preferably 75 to 55 % or 70 to 60 %, such as 65% based on the sum of binding portion and texturizing portion by mass. In a particular embodiment the mixture and consequently the resulting polymer article, consists of 55 to 75 % w/w texturizing portion and 25 to 45 % w/w binding portion. In a particular embodiment the mixture consists of 65 % w/w texturizing portion and 35 % w/w binding portion. All the ranges specifying the amounts of texturizing portion and binding portion described above, may suitably be used for the polyolefin texturizing portions and polyolefin binding portions previously described. Additionally, the ranges also apply to the bicomponent fiber binding portion previously described.

The shaped article is heated to provide the resulting polymer article. It is preferred that the heating proceeds under mechanical pressure to obtain a predefined shape and area density of the polymeric article. The mechanical pressure may be applied by using double rollers, preferably with integrated heating means. The pressure applied depends on the desired area density. The application of mechanical pressure may also contribute to the shaping of the polymer article.

The polymer article obtained by the method according to the invention can be used in a variety of end applications and the obtained shape and area density may be adjusted according to the application. Some applications may require further shaping of the polymer article by for example cutting. Two exemplary end applications of the polymer article is for use as a shock pad, for example in artificial turfs but also for playground flooring or the like, and for use in acoustics panels for improving the acoustics of for example indoor areas.

When the polymer article is a shock pad, such as for use under an artificial turf field, the polymer article is more dense than for acoustic panels. This will provide a shock pad having the desired impact absorption and/or resilience.

While the shock pad may be designed to have a specific area density, the design target may alternatively be predefined density of the shock pad.

Shock pads according to the invention, performed in the comparative tests panels from Kompan® in a similar manner in respect of Head Injury Criterion (HIC) according to ASTM F1292-18el) and vertical deformation etc.

One performance parameter for a shock pad according to the invention the Head injury Criterion (HIC) according to ASTM F1292-18el, where HIC scores for shock pads can be seen in example I.

When the polymer article is for use in an acoustic panel, the predefined area density of the polymer article is in the range of 800 to 2000 gsm, preferably 1000 to 1700 gsm, more preferably 1200 to 1400 gsm. Within the art the area density is indicated as gsm (grams per square meter).

While the polymeric article for use in an acoustics panel, may be designed to have a predefined area density, it may alternatively be designed to have a predefined density in the range of 100 to 200 kg/m ³ , preferably 125 to 175 kg/m ³ , more preferably 140 to 160 kg/m ³ and even more preferably about 150 kg/m ³ .

Polymer articles for use in acoustics panels typically have a thickness (caliper) in the range of 0.5 to 5 cm.

In a specific embodiment, the polymer article for use in an acoustics panel has a thickness of about 0.9 cm and an area density of about 1.35 kg/m ² (1350 gsm).

Tests showed that acoustic panels comprising a backbone of the polymer article according to the invention performed just as well as commercially available panels according to ISO 354:2003 standard and ASTM C423.

The performance of such an acoustics panel may be quantified by the sound absorption coefficient at a specific frequency or range of frequency as is done in for example ISO 354:2003 standard and ASTM C423. The sound absorption coefficients may be expressed as a weighted value across a frequency range according to the method of EN ISO 11654. Tests done on acoustic panels comprising a polymer article according to the invention having a caliper of about 0.9 cm and area density of 1350 gsm, had a weighted absorption coefficient a _w of 0.25 (MH), which is suitable for most use-cases in for example residential or commercial buildings.

Suitably the difference between TMbpl and TMbp2 is at least 10 °C, or at least 15°C, such as in the range of 10 to 50°C.

Similarly, the difference between TMtp and TMbp2 is suitably at least 10 °C, or at least 15°C, such as in the range of 10 to 50°C.

In further aspect of the invention there is provided a polymer article comprising or essentially consisting of a texturizing portion obtained from reclaimed artificial turf material and having a melting point TMtp, and a binding portion comprising at least two polymer components, wherein a first polymer component has a melting point TMbpl and a second polymer component has a melting point TMbp2, and wherein TMtp and TMbpl are preferably substantially the same, and wherein the texturizing portion is 55 to 75 % w/w and the binding portion is 25 to 45% w/w based on the sum of the texturizing portion and the binding portion by mass.

The polymer article may comprise a continuous phase and a discontinuous phase, the continuous phase comprising at least part of the texturizing portion and the first polymer component of the binding portion, and the discontinuous phase comprising the second polymer component of the binding portion. This configuration may arise from the processing according to the first aspect of the invention, wherein at least part of the texturizing portion and the first polymer component melt to form the continuous phase, while the second polymer component does not melt and remain solid, to thereby provide the discontinuous phase. The discontinuous phase may be observed as discrete particles in the continuous phase.

In an embodiment, the polymer article comprising or essentially consisting of a texturizing portion obtained from reclaimed artificial turf material and having a melting point TMtp, and a binding portion comprising at least two polymer components, wherein a first polymer component has a melting point TMbpl and a second polymer component has a melting point TMbp2, and wherein TMtp and TMbpl are substantially the same and wherein the polymer article consists of 55 to 75 % w/w of the texturizing portion and 25 to 45% w/w of the binding portion.

The polymeric article may be a shock pad, for example for an artificial turf field. In a particular embodiment, the polymeric article for use in an acoustics panel comprises about 30 to 40 % of binding portion, about 60 to 70% of texturizing portion, and the texturizing portion is reclaimed artificial turf fibre made of polyethylene.

Brief description of the drawings

In the following the invention will be described in relation to the schematic drawings in which

Figure 1 shows a shock pad according to the invention,

Figure 2 shows an acoustic panel comprising a polymer article according to the invention, and

Figure 3 shows a diagram of a method for producing a polymer article according to the invention.

Detailed description

Referring initially to Fig. 1 which shows a polymer article in the form of a shock pad 10 according to the invention. The shock pad 10 is in this embodiment a rectangular element comprising a fibrous material 11 shown in schematic manner. The fibrous material is obtained by mixing the texturizing portion and the binding portion and heating the resulting mixture to bond the portions together to obtain the fibrous material. During the process for producing the shock pad 10 the heated mixture is subjected to mechanical pressure to obtain the desired density of the shock pad 10. In this embodiment, the shock pad 10 has a relatively high density as indicated by the close packing of the fibers in Fig. 1.

Turning now to Fig. 2 which shows a polymer article in the form of an acoustics panel 20 according to the invention, comprising the polymer article 20 mounted on a panel 22. The polymer article 20 is in this embodiment less dense than the shock pad 10 of Fig. 1 as signified by the more loose packing of the fibers in Fig. 2. The polymer article 21 is typically referred to as a felt 21 in the context of acoustics panels. As for the shock pad, the desired density of the felt 21 is achieved by subjecting the heated mixture to an appropriate mechanical pressure and thereby compressing the mixture. For felt 21 the density may be adjusted to achieve the desired sound absorption and/or for achieving sufficient structural integrity for the panel to be installed by way of fasteners mounted through the felt.

The felt 21 is provided on element 22 which may be a backing plate 22 configured for being mounted on a surface, such as a wall or a ceiling or structural element thereof. The element 22 could also be a front-element configured to face towards an interior of a room in which it is mounted (not shown), which is provided for structural or aesthetic reasons. For some acoustics panels 20 an element 22 may provide on each opposite side of the felt 21, serving as a backing plate and a front-panel respectively. In Fig. 2 the element 22 is shown as a rectangular plate but other geometries could be considered, such as a plurality of elements spaced apart on a side of the felt 21.

Turning now to Fig. 3 which shows a diagram of a method for producing a polymer article according to the invention. Initially a texturizing portion 1 of reclaimed polymeric fiber is provided along with a binding portion 2 of polymeric fiber comprising a first and a second polymer component. The texturizing portion 1 and binding portion 2 are mixed in step c). Mixing the fiber material is advantageously done in a confined space pneumatically, i.e. by blowing a gas, such as air, through the fiber whereby a well-mixed mixture 3 is obtained. The mixture 3 is then dosed and shaped in step d) providing a shaped mixture 4 having a desired shape. The desired shape of the shaped mixture 4 may be a plate. Suitable fiber dosing dispenser are available commercially. Subsequently, the shaped mixture 4 is heated in step e) to a processing temperature TH which is greater than a melting temperature T/vitp of the texturizing portion and greater than a melting temperature TMbpl of the first polymer component of the binding portion 2, but which processing temperature TH is less than the melting temperature TMbp2 of the second polymer component of the binding portion 2. This provides a shaped and heated article 6 which is allowed to solidify in step f) to provide a polymer article 6. Solidifying in step f) may comprising actively cooling or allowing to cool at ambient temperatures. The desired density or area density of the material may be controlled by applying mechanical pressure in step e) to compress shaped mixture. This mechanical pressure may be applied prior to heating, during heating and/or after heating in step e). The mechanical pressure may also contribute to the shape of the polymer article. For example, in step d) may provide a mixture 4 shaped as a rectangular plate, and the mechanical pressure applied in step e) may determine the final thickness or caliper of the plate shaped polymer article 6. The process may be an airlaying process. The processing temperature TH is achieved in step e) by a heating means, such as hot air blower, rollers with integrated heating, or passing the mixture trough a heated chamber. The processing temperature may be measured at a surface of the mixture.

In the following, the embodiments and details of the invention is described in greater detail.

The texturizing portion can be an artificial polymer fiber from a suitable source such as artificial turf, carpets, rugs, synthetic textiles and the like. Preferred is artificial turf.

The texturizing portion is in preferred embodiments a reclaimed and pure artificial grass fiber component. In a preferred embodiment the grass fiber is obtained by a method described in W02015059094 to the same applicant. Hence, the fiber material is substantially pure, such as consisting mostly of polyethylene. Smaller amounts of polypropylene may also be present if the grass fiber was made of a mixture.

The binding portion is a material comprising at least two polymer components, preferably a fibrous material, wherein a first polymer component (bpl) has a melting point TMbpl and a second polymer component (bp2) has a melting point TMbp2, preferably the melting point of the first polymer component TMbpl is substantially the same as the melting point of the texturizing portion TMtp. Preferably the binding portion is a bicomponent fiber material where the first polymer component constitutes a substantial portion of the surface area of the fiber material. The first and second polymer component of the binding portion may be a polyolefin and it is preferred that the first polymer component is made of the same material as the texturizing portion. More preferred the first polymer component is a polyethylene (PE). The second polymer component is a polyolefin having a higher melting point than that of the first polymer component. In preferred embodiments where the fist polymer component is a polyethylene (PE), the second polymer component is a polypropylene (PP). In other preferred embodiments, the first polymer component is a PP and the second component is a PP with a higher melting point than the PP of the first polymer component. The ratio of the first polymer component to the second polymer component is 3:1 to 1:3, such as 2:1 to 1:2, preferably around 1:1.

The binding portion may suitable be a bicomponent fiber made from the first and second polymer component. Several configurations of bi-components fibers are known to the skilled practitioner, incl. side-by-side and islands in the sea. Suitably for the invention, the binding portion is a bicomponent fiber having a core-shell configuration, with the first polymer component forming the shell and the second polymer component forming the core of the bicomponent fiber. These bicomponent fibers may have the properties of the first and second component described in the immediately preceding paragraphs. As will be appreciated by the skilled practitioner the melting point TMtp of the texturizing portion may depend on the composition of the reclaimed polymeric fiber. Grass fiber materials from artificial turfs are typically made of polyethylene (PE) or polypropylene (PP). Commercial PE may have a melting point in the range of 95 to 135 °C depending on the type, where low density PE's may be in the lower end of 95 to 120 °C and high-density PE's are in the range of 125 to 135 °C. PP has a higher melting point and for commercial PP's it may be in the range of 160 to 171 °C, but the melting point of some types of PP can be as low as 130 °C

According to the invention, the binding portion comprises the first polymer component which preferably has a melting point TMbpl close to or substantially equal to the melting point TMtp of the texturizing portion, and a second polymer component which has melting point TMbp2 which is greater than to the melting point TMtp of the texturizing portion. Hence, the binding portion may be selected according to the melting point of the texturizing portion, which is within the knowledge of the skilled practitioner. Suitable binding portions are commercially available.

The temperature difference from the TMbp2 to TMbpl and/or to TMtp may suitably be at least 10 or 15 °C.

Hence, in an embodiment where the texturizing portion is primarily made of PE having a melting point of about 110 °C, the first polymer component of the binding portion could PE having a melting point of about 105 to 115 °C or about 110 °C, while the second polymer component could be a PE having a melting point of about 130 °C or alternatively a PP having a melting point of about 165 °C. In the embodiments, the mixture may be heated to a processing temperature of for example 120 C, where the texturizing portion and first polymer component will melt, but the second polymer component does not.

In further embodiment, the texturizing portion comprises PE having a melting point (TMtp) in the range of 110 to 120 °C, while the first polymer component is PP with a melting point in the range of 135 to 145 °C, and the second polymer component is a PP having melting point of about 155 to 165 °C. The processing temperature for this embodiment is thus at least 135 °C. It will be appreciated that according to the invention, it is the difference(s) between the melting points TMtp, TMbpl, and TMbp2, which is of relevance, and as such the method used to determine the melting points may be any suitable method used in the in the field of thermoplastics as long as the same method is used when comparing. Hence, the melting point referred to herein may be obtained by differential scanning calorimetry (DSC), e.g. according to ISO 11357-3. Temperature differences disclosed herein may refer to the differences between the peak apexes in DSC heat-flow vs. temperature plots.

The texturizing portion may in some embodiments be reclaimed polymeric fiber material comprising a mixture of polymeric fibers. When the texturizing portion comprises a mixture of polymeric fibers having a plurality of melting temperatures, the melting temperature TMtp may be the melting temperature of polymeric fiber which forms the greatest part of the texturizing portion. Additionally or alternatively, the melting temperature TMtp may be the melting temperature at which at least 50 %, at least 75 %, at least 80 % or at least 90 % of the texturizing portion is melted, by weight. Grass fiber from an artificial turf may for example comprise about 80 to 95 % of a PE while the rest is substantially PP, in which case the melting temperature TMtp will be that of the PE. The content of different polymeric fiber in a mixture may be quantified using DSC by the melting enthalpies. The PerkinElmer DSC 8500 may be suitable for this, and can maintain isothermal steps during melt transitions to increase the resolution. Alternative methods for quantifying polymer content are known, such as FT-IR, TGA-FTIR and NMR. If the different polymeric fibers can be distinguished visibly, e.g. by having different colours, the relative contents may be determined by sorting a sample and weighing the obtained fractions.

For some purposes it is preferred that the binding portion also comprises a flame retardant component. Suitably the flame retardant can be flame retardant fillers incorporated into one or both polymers of the binding portion. Flame retardants are well known to the skilled person.

Auxiliary components of the polymer article can also be provided separately from the binding portion. The auxiliary components may for example be added during or prior to step c. in order to mix them into the polymer article, or after step c. if the auxiliary component is to form for example a coating on the polymer article. Auxiliary components may include colourants.

Auxiliary components form a minor part of the polymer article, which primarily comprises the texturizing and binding portions. The sum of texturizing and bind portions may thus constitute at least 80 %, 90 % or 95 % of the polymer article by mass.

In some embodiments, the method comprises the step of providing a protective sheet on one or more surfaces of the shaped mixture obtained in step d. The protective sheet is a polymer material and has a melting temperature which exceeds the processing temperature. The protective sheet may for example be made from PP. The protective sheet may facilitate processing, by reducing the risk of the shaped mixture adhering to processing equipment in step e. and subsequent steps. The protective sheet(s) is/are arranged to cover one or more surfaces of the shaped mixture. The shaped mixture may for example be a rectangular plate shape having two major surfaces connected by minor surfaces, and the protective sheet(s) may be arranged on one or both of the major surfaces.

An example of a commercially available binding portion usable in the invention are the PE/PP series from ES Fibervisions such as Al-Adhesion II. These bicomponent fibers are known to be good for bonding non-synthetic fibers, but have now been found to be excellent also for forming a polymer article according to the invention using artificial turf grass fiber.

It is contemplated that the polyethylene of both the texturizing and binding portion is selected from but not limited to HDPE, LDPE, and LLDPE. Both the first and second polymer component of the binding portion may be selected from these types of PE.

The melting point of the PE is as the skilled practitioner knows dependent on the density/crystallinity of the PE, and PE binding portion may be selected as is appropriate for the specific PE texturizing portion on a case by case basis. Hence, a relatively low-melting PE texturizing portion may be mixed with a binding portion having a first polymer component of a similarly low-melting PE, and second polymer component made of a comparatively high-melting PE.

The dimensions and area density of the polymer article depends on the intended application. In the following details and advantages of the invention is described by way of non-limiting examples.

Example I

Polymer articles with varying density and thickness for use as shock pads were produced according to the method of the invention and tested according to ASTM 1292 and the HIC, Gmax and CFH score is provided in Table I.

Table I