Field of the Invention

The present invention relates to a laminate and collapsible tubes and pouches which are commonly used for packing home and personal care products, especially toothpastes and cosmetic creams.

Background of the Invention

Collapsible tubes are generally made of laminates, i.e. , materials that are multilayered and where the layers are joined or connected to each other, i.e. laminated to each other, e.g., by coextrusion or adhesive lamination. As laminates are often used for packaging a variety of products, certain features, and properties, especially barrier properties have assumed importance.

EVOH (Ethylene vinyl alcohol) is often co-extruded with polyolefins to improve the barrier properties of laminates that primarily contain such polyolefins. EVOH causes the flavours and fragrance to be retained for longer. Aluminium is also used widely to improve barrier property, particularly of lamitubes (tubes made from laminated films). Laminates containing Aluminium are often called Aluminium based laminates (ABL). Usually, a thin layer of about 10 pm of Al is sufficient. Usually, the metalized films are made of polyolefins, especially polyethylene, e.g., High Density Polyethylene (HDPE). Tubes of laminates containing aluminium are called ABL tubes. However, Aluminium based laminates generally cannot be easily recycled in PE recycle stream. Therefore, plastic based laminates (PBL) were invented.

It does not imply that ABL tubes are phased out. In PBL tubes, EVOH (ethylene vinyl alcohol) based polymers are used instead of Aluminium to make it easily recyclable, whilst still having the desired barrier properties. In PBL tubes, the amount of EVOH is usually expressed as wt% of the multilayer laminate. Alternatively, it may be expressed in terms of % thickness of the total thickness of the laminate. In either case, limits are imposed on the amount of EVOH in the laminate due to technology and the problems that elevated levels may pose in recyclability of the laminates. In addition, tubes are also made of laminates that do not contain any barrier layer. Plastics are used in a wide variety of applications, such as packaging and consumer goods.

Plastics are in high demand in these applications due to their relatively low production costs and good balance of material properties.

To meet the increasing demand, millions of tons of plastics are produced globally. Majority of such synthetic plastics are produced from increasingly scarce fossil sources, such as petroleum and natural gas. The production of plastic from fossil sources contributes to raising the levels of greenhouse gases. The ubiquitous use of plastics has consequently resulted in millions of tons of plastic waste being generated every year. Most of the used plastics end in landfills, other as litter and still others end in water bodies.

There is environmental pressure on industries to recycle waste polymers, particularly those used in packaging applications. Plastics recycling has emerged as a solution to mitigate the issues associated with the wide-spread usage of plastics. The single or mixed streams of plastic waste are sorted, washed, and reprocessed into pellets that are suitable for re-use in plastics processing.

US10889093 B2 (Colgate) discloses a laminate in which the uppermost and lowermost layer have molecular orientation that results in a non-zero stress value for each layer. The multi-layer structure has a net stress value that is less than the greater stress value of the plurality of layers.

WO20098947 A1 (Constantia) discloses packaging laminate with a first laminate layer and a second laminate layer, the first laminate layer being a co-extruded and bidirectionally stretched composite of a cavitated substrate layer with 5 to 30% by weight, preferably 15 to 25 % By weight, cavitating agent and with a PE content of at least 60% by volume, a connection layer and a barrier layer made of a barrier polymer, preferably made of polyamide or ethylene-vinyl alcohol copolymer, with a maximum thickness of 20% of the total thickness of the first laminate layer, wherein the connecting layer is arranged between the substrate layer and the barrier layer and the first laminate layer is connected to the second laminate layer at its barrier layer .

WO1 9172932 A1 (Colgate) discloses a recyclable package, comprising: an outer layer consisting essentially of a first high-density polyethylene (HDPE); an inner layer comprising a second HDPE; a barrier layer positioned between the outer layer and the inner layer; a first bonding layer positioned between the outer layer and the barrier layer; and a second bonding layer positioned between the inner layer and the barrier layer.

EP3785895 A1 (Neopac, 2021) discloses a laminate for a tube package. The laminate has at least three layers, an inner polyolefin layer and an outer polyolefin layer and a barrier layer sandwiched between the outer polyolefin layer and the inner polyolefin layer. The barrier layer comprises at least one polyolefin comprising barrier foil like a monolayer foil or a coextruded foil or a laminate thereof and wherein at least 90 % of all polymers of the container are made of polyolefin of the same kind. An object of the invention is to provide a preferably gas-tight, and liquid-tight collapsible tube made of thermoplastic material that can be recycled in monomaterial recycling streams without any separation step involved.

An object of the invention is to provide sustainable laminates for packaging applications where the laminates are thinner, yet technically superior, e.g., to make tubes and pouches. Another object is to provide laminates that are flexible yet tough.

The present invention provides laminates that may or may not contain a barrier layer. When laminates according to the invention comprise EVOH or an alternative barrier layer, the present invention enables reduction in the wt% or total content of EVOH whilst still maintaining stiffness and flexibility. As a result, the present invention enables reduction in thickness by up to 30%, as compared to contemporary laminates which need to be thicker in comparison, to be able to provide the required technical properties. Therefore, the invention provides a sustainable technology for packaging applications.

Summary of the Invention

In accordance with a first aspect disclosed is a multilayer laminated film comprising: a) a printable polyethylene layer; b) a sealant polyethylene layer; and, c) therebetween an intermediate layer comprising polyethylene whose tensile elongation along machine direction is from 20 to 200% wherein the intermediate layer is extrusion laminated to the printable layer and sealant layer.

Extrusion lamination of the intermediate layer to the printable and the sealant layer makes the laminates flexible, yet tough. Detailed Description of the Invention

The term "comprising" is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word "about".

It should be noted that in specifying any range of concentration or amount, any particular upper concentration can be associated with any particular lower concentration or amount.

The multilayer laminated film of the invention comprises: a) a printable polyethylene layer; b) a sealant polyethylene layer; and, c) therebetween an intermediate layer comprising polyethylene whose tensile elongation along machine direction is from 20 to 200%. wherein said intermediate layer is extrusion laminated to said printable layer and sealant layer

As used herein the term “flexible film” denotes a flexible sheet of polymer which has a thickness dimension which is substantially smaller in relation to its breadth and width and is used primarily for preparing a package for storing consumer goods which are in a solid, semi-solid and/or liquid form. The flexible film may be presented as a wound roll of material. Flexible film are usually used for preparing bags, sachets, pouches and other sealed package for holding consumer product.

As used herein the term "laminate" refers to layers of film bonded together, in this case a multilayer laminate. The bonding may be achieved by extrusion, heat treatment, adhesives or other method known in the art to laminate two films or sheet.

As used herein, printable layer refers to the layer farthest away from a product, such as toothpaste, when packaged with a packaging, e.g., tube, made from the multilayered laminated film. As used herein, sealant layer refers to the layer located closest or proximal to the product when packaged with a packaging, e.g., tube, made from the multilayered laminated film.

As used herein “intermediate layer” refers to the layer located between the printable and sealant layers, such that one side of the intermediate layer faces the sealant layer and the other side (back or opposite side) of the intermediate layer faces the printable layer.

"Extrusion laminated" means gradual melting of the thermoplastic resin that is used as adhesive and which is fed into an extruder in granular or powder form until it becomes fluid. The molten resin is cast through a die between the plastic films and run over cylinders where the extrudate is cooled and solidified. It is preferred that the cylinders are chilled to accelerate the cooling process and avoid shrinkage, holes or melting.

The term “high density polyethylene” HDPE, used herein refers to a polyethylene having a density in the range of 0.941 to 0.970 gm/cm ³ .

The term “medium density polyethylene”, MDPE, used herein refers to a polyethylene having a density in the range of 0.926 to 0.941 gm/cm ³ .

The term “low density polyethylene”, LDPE, used herein refers to a polyethylene having a density in the range of 0.919 to 0.935 gm/cm ³ . The term “linear low density polyethylene” used herein refers to a polyethylene having a density in the range of 0.919 to 0.925 gm/cm ³ .

The term “stiffness” used herein refers to resistance of a material to deformation under an applied force.

The term “Young’s modulus” used herein refers to the property of a material that is calculated by measuring the ratio of stress to strain incurred in the material. Young’s modulus gives a measure of the stiffness of the material or the ease with which it can be stretched or bent. Higher the value of the young’s modulus, lesser is the extent to which a material can be stretched or elongated, higher is the stiffness. It is measured in terms of N/m ² or Pascal (Pa). The term “melt flow index” or “MFI” used refers to the grams of a polymer flowing per 10 minutes through a capillary tube. It is a measure of the ease of flowing of the polymer melt denoted in terms of g/10 min. The term “density” used herein refers to the mass of polymer present per unit volume of the multilayer film. It is measured in terms of g/cm ³ .

The term "polyolefin(s)", as used herein, encompasses a class of thermoplastic polymers that are widely used in the consumer and petrochemicals industry and refers to a polymer that comprises, in polymerized form, a majority amount of olefin monomer, for example ethylene or propylene (based on the weight of the polymer), and optionally may comprise one or more comonomers. Polyolefins are typically produced from a simple olefin (also called an alkene with the general formula (C _n H _2n ) as a monomer. For example, polyethylene (PE) is the polyolefin produced by polymerizing the olefin ethylene (C2H4). Polypropylene (PP) is another common polyolefin which is made from the olefin propylene (C3H6).

Polyethylene" or "ethylene-based polymer" mean polymers comprising greater than 50% by weight of units which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). It is preferred that polyethylene means Low Density Polyethylene (LDPE); Linear Low-Density Polyethylene (LLDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE). More preferably polyethylene means at least one of Low Density Polyethylene (LDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE).

In accordance with the invention, it is preferred that all layers of the multilayer laminated film are of the same kind of polyethylene selected from Low Density Polyethylene (LDPE); Linear Low- Density Polyethylene (LLDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE). More preferably polyethylene means at least one of Low Density Polyethylene (LDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE).

Alternatively, in accordance with the invention, it is preferred that all layers of the multilayer laminated film are of different kinds, i.e. , non-identical polyethylene, selected from Low Density Polyethylene (LDPE); Linear Low-Density Polyethylene (LLDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE). More preferably polyethylene means at least one of Low Density Polyethylene (LDPE); Medium Density Polyethylene (MDPE); or High Density Polyethylene (HDPE). For example, the printable polyethylene layer comprises primarily HDPE and the sealant polyethylene layer comprises primarily MDPE or LDPE.

Preferably melt index (h) of polyethylene is 50g/10 minutes or less, preferably 20 g/10 minutes or less where the Melt index is measured at the conditions of 190°C and a standard weight of 2.16 Kg. The polyethylene has a melt index (h) of up to 15 g/10 minutes in some embodiments. The polyethylene has a melt index (h) of up to 10 g/10 minutes in some embodiments. In some embodiments, the polyethylene has a melt index (h) less than 5 g/10 minutes.

Various commercially available polyethylene include LDPE such as DOWLEX™ linear low- density polyethylene commercially available from The Dow Chemical Company, such as DOWLEX™ 2038.68G. Examples of commercially available HDPE that can be used in embodiments of the present invention include DOW™ HDPE resins and DOWLEX™. Any other suitable commercially available polyethylene may be selected for use in polymer composition based on the teachings herein.

LDPE is readily available, e. g., PE 1017 (Ml=7; d=0.917) from Chevron, San Francisco, California, SLP 9045 (Ml=7.5; d=0.908) from Exxon, Houston, Texas, and ZCE 200 (Ml=3; d=0.918) from Mobil Chemical Corporation, Fairfax, Virginia. The term LLDPE means a copolymer of ethylene and a minor amount of an olefin containing 4 to 10 carbon atoms, having density of from about 0.910 to about 0.926 g/cm<3> and Ml from 0.5 to about 10 g/10 min. LLDPE is readily available, e.g., DOWLEX® 2045.03 (Ml=1 .1 ; d=0.920) from Dow Chemical Company, Midland, Michigan.

MDPE is readily available, e. g., DOWLEX® 2027A from The Dow Chemical Company, and Nova 74B and Nova 14G from Nova Corporation, Sarnia, Ontario, Canada.

The

It is preferred that the printable polyethylene layer comprises sub-layers of LDPE, HDPE, MDPE and LLDPE, where sub-layers of HDPE are more than that of sub-layers of LLDPE and MDPE.

Preferably, the printable PE layer is not uniaxially oriented, i.e. this layer is preferably not stretched in the machine direction. Preferably, the printable PE layer is made up of 3 to 7, more preferably 3 to 5 and even more preferably 5, sub-layers of LDPE, LLDPE, MDPE, HDPE. The sealant polyethylene layer

It is preferred that the sealant polyethylene layer comprises sub-layers of HDPE and LLDPE, LDPE, MDPE where sub-layers of HDPE are more than that of sub-layers of LLDPE and MDPE Preferably, the printable PE layer is made up of 3 to 7, more preferably 3 to 5 and even more preferably 5, sub-layers of LDPE, LLDPE, MDPE, HDPE.

For example, the table below shows the wt% of MDPE and HDPE in some commercially available resins.

Table 1

The intermediate layer

Tensile elongation along machine direction (MD) of the intermediate layer comprising polyethylene, is from 20 to 200%. It is preferred that the tensile elongation is 30 to 200%, more preferably 30 to 100%., still more preferably 50 to 100% and optimally it is 70 to 100%.

Tensile elongation is defined as stretching or deformation that a material undergoes as it is pulled in tension. It is measured by the change in length (L) of the sample at break with respect to the initial length (L _o ).

Tensile elongation (%) = 100 X (L-Lo)/Lo

It is also known as percentage of elongation; % elongation is a measurement that captures the amount a material will deform up to break. Percent elongation is a way to measure and quantify the ability to deform without break of a material. Higher values of % elongation in film express that the film is ductile or flexible or can sustain higher tensile force without breaking. However, lower elongation values in film indicate brittle behaviour - which is prone to break when pulled or tensile force is applied. In addition, lower value of elongation means the film has higher tensile strength. It is preferred that % elongation is determined by ASTM D882.

It is preferred that tensile elongation along cross direction (CD) of the intermediate layer is 400 to 700 %. Cross direction generally means the direction perpendicular to the machine direction.

It is preferred that water vapour transmission rate (WvTR) of the intermediate layer at 37.8°C and 90% RH is 0.5 to 10 g/mm ² /day. It is preferred that the WvTR is determined by ASTM F1249.

In the multilayer laminated film of the invention, it is preferred that thickness of the intermediate layer accounts for 5 to 15% of total thickness of the laminate.

In one aspect of the invention, the intermediate layer is devoid of barrier-properties. The term devoid of barrier-properties means that WvTR of said intermediate layer at 37.8°C and 90% RH is less than 0.5 g/mm ² /day.

Preferably the intermediate layer is metallized. Metallization is carried out by a variety of means such as vacuum metallization. Such metallization makes the film appear glossy and shiny.

It is further preferred that the intermediate layer is a 5-layered structure consisting of, in sequence, a primary lamination layer, a first tie layer, a middle layer devoid of barrier properties, a second tie layer and a secondary lamination layer.

An example of PE film that is devoid of barrier properties, that may be used as the intermediate layer, is commercially available as lnnoPure25.

Alternatively, the intermediate layer comprises a layer having barrier properties. Such properties are due to the presence of a barrier layer or a sub-film.

When present, preferably the barrier coating or sub-film accounts for 0.0001 to 30 % of total thickness of said intermediate layer. It is preferred that the barrier layer or sub-film comprises Ethylene-vinyl alcohol copolymer or aluminium or a combination of vinyl alcohol copolymer and aluminium. Further preferably the thickness of said barrier layer accounts for 1 to 3 % of total thickness of said laminate. It is preferred that when the coating is of Aluminum, it is deposited by vapour-deposition. This method is well-known in the art. Vacuum deposition includes the batch-cycle method and barrier coating includes the continuous system method. Before applying any coating, the surface of the polyolefin film may be treated to increase its surface energy. This may be done by any of several known and conventional techniques.

It is further preferred that the intermediate layer is a 5-layered structure consisting of, in sequence, a primary lamination layer, a first tie layer, a mid layer comprising said barrier layer, a second tie layer and a secondary lamination layer. An example of PE film with barrier properties, that may be used as the intermediate layer, is commercially available as lnnopureHB23.

Therefore, alternatively it is preferred that the intermediate layer is a 5-layered structure consisting of, in sequence, a primary layer having barrier properties, a first tie layer, a mid layer, a second tie layer and a secondary lamination layer. In such a case, it is preferred that the primary lamination layer is metallised.

It is preferred that total thickness of the laminate is 175 to 350 pm. More preferably it is 200 to 350 pm, further preferably 210 to 350 pm. The range 175 to 350 pm generally applies to laminates useful for making collapsible tubes and the range 175 to 350 pm generally applies to laminates for making pouches such as stand-up pouches.

It is particularly preferred that the film comprises a first lamination layer between the printable polyethylene layer and the intermediate layer, and a second lamination layer between the sealant polyethylene layer and the intermediate layer. When present, it is preferred that thickness of each lamination layer is 10 to 30 pm. It is preferred that thickness of the printable polyethylene layer and of the sealant polyethylene layer is 80 to 150 pm.

The film may include suitable additives, for example stabilizers, neutralizers, lubricants or antioxidants. In principle, additives used for polyolefins, such as polyethylene or polypropylene, are also suitable for cycloolefin polymer films. Examples of UV stabilizers which can be used are absorbers, such as hydroxyphenyl benzotriazoles, hydroxy benzophenones, formamidine or benzylidene camphor; quenchers, such as cinnamic esters or nickel chelates; free- radical scavengers, such as sterically hindered phenols, hydroperoxide scavengers, such as nickel or zinc complexes of sulfur-containing compounds, or light stabilizers and mixtures thereof. Examples of suitable lubricants include fatty acids and esters, amides and salts thereof; silicones or waxes, such as polypropylene or polyethylene waxes. Examples of antioxidants which can be added are free-radical scavengers, such as substituted phenols and aromatic amines, and/or peroxide scavengers, such as phosphites, phosphates and thio compounds.

Package and use

The invention also relates to a lamitube comprising a cylindrical body, a shoulder, and a cap, wherein said body is made of a multilayered laminate of the first aspect of the invention. It is preferred that ovality of the body is in the range of 1 to 10%, more preferably 2 to 8% and even more preferably from 3 to 6%. The cap may also be optional as it is a separate article that can be made by a standard industrial process.

The film may be used as such for any suitable packaging application, preferably lamitubes. Pouches may also be made by any known means such as by form-fill-seal process. When the intended application is to make pouches; the innermost material should be sealable, preferably by heat sealing. However, it is preferred that the film is used to make laminates, which in turn are used to make, preferably, squeezable tubes. Several processes of making lamitubes are well known in the art.

When the intended application is to make squeezable tubes, the outer and inner films should be capable of being lap-sealed (also called side seam), preferably by application of heat, so that the sides may be sealed off after a product has been filled. In such cases, the innermost film should also bond with itself, so that the bottom of the tube may be closed after a product has been filled.

The lamitube comprises a body for storing a packaged product, and shoulder which comprises an outlet for dispensing the packaged product, and a cap or closing off the tube.

The body may at the outside be provided with a print, which is mostly applied previously.

In a usual process for manufacturing the tubes, the body and the shoulder are manufactured separately, and subsequently welded together. The caps for the tubes are usually manufactured separately. Upon manufacturing the tube body, the multilayer laminate is introduced into a device that is provided with a preform with the shape of body and is provided with expansion hubs for the expansion of the film to the desired dimensions. A guiding ensures that rims of the multilayer laminate overlap. The rims are welded together by means of a fully continuous heat welding system.

The laminate is cut to size by means of a rotating knife, thus obtaining tubes of the desired length. The obtained tubes are put on a compression mandrel.

The upper part of the tube, or tube shoulder is pressed in the right shape and desired dimensions in a separate press, and provided with a small quantity of molten multilayer packaging film. The compression mandrels provided with the tube body are introduced into the press in which the shoulder is pressed, and welded to the shoulder. The press is cooled, the tubes are removed from the press, and transferred to another device in which each tube is provided with a cap. Devices to manufacture such tubes are available from a variety of suppliers, example AISA. The tubes are brought to a filling device and filled with the desired cosmetic product through the bottom which subsequently is heat sealed.

The invention will now be described with the help of non-limiting exemplary embodiments.

Structures of some preferred and comparative multilayered laminates are described below.

Printed PE layer 125 pm/first lamination layer 20 pm LDPE/lntermediate layer 25 pm (25 microns) MDO-PE/Second lamination layer 20 pm/Sealant PE layer 125 pm.

Printed PE layer 100 pm/first lamination layer 20 pm LDPE/lntermediate layer 25 pm MDO-

PE/Second lamination layer 20 pm/Sealant PE layer 100 pm

Printed PE layer 100 pm/first lamination layer 20 pm LDPE/lntermediate layer 25 pm MDO-PE metallised/Second lamination layer 20 pm LDPE/Sealant PE layer 100 pm.

Example 4:

Metalized Printed PE layer 100 pm/first lamination layer 20 pm LDPE/lntermediate layer 25 pm MDO-PE/Second lamination layer 20 pm LDPE/Sealant PE layer 100 pm.

MDO indicates machine direction orientation.

Details of the intermediate layer are:

The intermediate layer of MDO PE is a PE film for standard applications and properties. The layer may contain additives added during the blown process for slip/block resistance, opaque density, anti-static etc. based on specifications desired. The intermediate layer may be symmetric or asymmetric.

For the examples shown in table 2 for laminates 300/0 and 250/0, lnnoPure25 was used as the intermediate layer where the tensile elongation along machine direction is 103% and that along the cross direction is 630% and the WvTR (37.8°C, 90% RH) is 7.6054 gm/m ² /day; and for laminates 300/6 and 250/6, lnnoPureHB23 was used as the intermediate layer where the tensile elongation along machine direction is 37% and that along the cross direction is 412% and the WvTR (37.8°C, 90% RH) is 5.56 gm/m ² /day. Exemplary details of the printed polyethylene layer are as follows:

Layer-1 20 pm LLDPE/Layer-2 20 pm HDPE/Layer-3 barrier layer 20 pm HDPE/Layer-4 20 pm

HDPE/Layer-5 20 pm LLDPE

Alternative exemplary details of a printable polyethylene layer are as follows:

Layer-1 20 pm LLDPE/Layer-2 20 pm HDPE/Layer-3 barrier layer 20 pm HDPE/Layer-4 20 pm HDPE/Layer-5 20 pm HDPE

Exemplary details of the sealant polyethylene layer are:

Layer-1 20 pm LLDPE/Layer-2 20 pm HDPE/Layer-3 barrier layer 20 pm HDPE/Layer-4 20 pm HDPE/Layer-5 20 pm LLDPE

Table 2 details some properties of multilayer laminated films in accordance with the invention.

In the table below, the description of the laminate is indicated by two numbers, e.g., 300/6 in which the first number indicates the total thickness of the laminated film in microns and the second number indicates thickness of the barrier layer e.g. EVOH, in microns, within the intermediate layer. Where the second number is 0 it means there is no EVOH in the intermediate layer in the film.

TABLE 2

Further experiments were carried out to evaluate the effect of extrusion lamination as compared to adhesion lamination using test laminates 250/0 where the number 250 indicates the total thickness of the laminated film in microns and the number 0 indicates absence of EVOH in the intermediate layer.

Composition of the test laminates was as follows:

For extrusion:

92 microns print PE layer I 20 microns extrusion PE (lamination) layer I 25 microns MDO-PE without EVOH I 20 microns PE extrusion (lamination) layer I 92 microns PE sealant layer; thus, the laminate is 250/0.

For adhesion:

111 microns print PE layer 12-3 microns adhesive layer 125 microns MDO-PE without EVOH 12- 3 microns adhesive layer / 111 microns PE sealant layer.

For the laminates in table 3 below, lnnoPure25 was used as the intermediate layer where the tensile elongation along machine direction is 103% and that along the cross direction is 630% and the WvTR (37.8°C, 90% RH) is 7.6054 gm/m ² /day.

The data obtained for the two laminates was as shown in table 3 below:

Table 3