A process for the preparation of a water-soluble film, and packages formed therefrom

Abstract

The invention relates to a cast extrusion process for preparing a polyvinyl alcohol (PVOH) film, the process comprising the steps of: a. extruding a composition comprising at least one PVOH resin onto a first heat transfer roller; and b. feeding the composition from the first heat transfer roller onto a second heat transfer roller; wherein the first heat transfer roller has a temperature of from 20°C to 90°C, and the second heat transfer roller has a temperature which is less than the temperature of the first heat transfer roller.

Description

[0001] PAT 15669- WO-PCT

[0002] 1

[0003] A PROCESS FOR THE PREPARATION OF A WATER-SOLUBLE FILM, AND PACKAGES FORMED THEREFROM

[0004] Technical Field of the Invention

[0005] The present invention relates to a process for the preparation of a water-soluble film, in particular of a polyvinyl alcohol film. The invention further relates to a package comprising such a polyvinyl alcohol film.

[0006] Background to the Invention

[0007] Current commercially available water-soluble films used for complex multichamber thermoforming processes, for example in the manufacture of water-soluble automatic dishwashing (ADW) capsules, are mainly produced via an aqueous solution cast process. In aqueous solution casting, a polymer is dissolved or dispersed in solution, coated onto a carrier substrate, and then the water or solvent is removed by drying to create a solid layer on the carrier. The resulting cast layer can be stripped from the carrier substrate to produce a standalone film.

[0008] Aqueous solution cast processes may be considered suitable as the process allows for a water content in the produced film of greater than 3%. A water content of greater than 3% allows the water to act as a plasticiser, therefore, providing elasticity to the film. Aqueous solution cast processes also may allow for the use of polyvinyl alcohol-poly carboxylate-polyvinyl acetate copolymer resins, which may be considered to provide greater freedom in adjusting properties of the resultant film compared to polyvinyl alcohol homopolymers.

[0009] Further, aqueous solution cast processes require a significant amount of energy to dissolve all solid materials into a solution and then to evaporate the water or solvent in which the solid materials have been dissolved, therefore, increasing the cost associated with aqueous casting processes. Even further disadvantageous^, manufacturing facilities for carrying out aqueous solution casting require considerable space due to the required step of drying the resulting cast layer. Thus, manufacturing facilities which employ aqueous casting processes often need to designate significant floorspace to the equipment used for the aqueous casting process, therefore, limiting the operations of the facility to carry out additional work. PAT 15669- WO-PCT

[0010] 2

[0011] Water-soluble films may also be produced by blown extrusion processes. Blown extrusion processes are relatively complicated and difficult to control as such processes include exposing water-soluble films to two or three thermal stress steps. Such thermal stress steps include blending the solids and liquids under high shear forces and compounding the subsequent material in an extruder before then melting the material to manufacture a film.

[0012] It is an object of embodiments of the present invention to at least partially overcome or alleviate at least one of the above problems and / or to provide an improved process for the preparation of a water-soluble film, in particular a polyvinyl alcohol film.

[0013] Summary of the Invention

[0014] According to a first aspect of the invention, there is provided a cast extrusion process for preparing a polyvinyl alcohol (PVOH) film, the process comprising the steps of: a. extruding a composition comprising at least one PVOH resin onto a first heat transfer roller; and b. feeding the composition from the first heat transfer roller onto a second heat transfer roller; wherein the first heat transfer roller has a temperature of from 20°C to 90°C, and the second heat transfer roller has a temperature which is less than the temperature of the first heat transfer roller.

[0015] Advantageously, the cast extrusion process of the invention provides for a PVOH film which exhibits improved mechanical properties, for example thermoformability, compared to films, in particular PVOH films, produced by other known film manufacturing methods, for example aqueous solution casting.

[0016] Surprisingly, it was discovered that the process according to the invention prepares a PVOH film which possesses a higher sealing strength and better thermoforming properties compared to PVOH films formed by known film manufacturing methods, for example aqueous solution casting. PAT 15669- WO-PCT

[0017] 3

[0018] Beneficially, the cast extrusion process of the invention avoids the restrictions and limitations of aqueous solution cast processes and blown extrusion processes of the prior art. Beneficially, the cast extrusion process of the invention is a relatively low energy and, therefore, relatively low cost, process for preparing a PVOH film. Such benefits may be applicable to cast extrusion processes generally when compared to aqueous solution casting and blown extrusion.

[0019] Moreover, the advantageous mechanical properties of the PVOH film formed by the invention, for example its enhanced thermoformability, mean that the PVOH film prepared by the invention can be used to create monodose articles, such as ADW pouches, and complex articles such as complex pouch designs which comprise multiple compartments.

[0020] Further advantageously, the invention provides for a greater control of the thickness of the prepared PVOH film than is found with known processes for preparing a PVOH film, such as blown extrusion. This means that, compared to known processes, the process of the invention provides for a PVOH film with a homogenous thickness and in which the thickness of the film can be accurately tailored to the desired use of the film, for example as an ADW pouch.

[0021] Moreover, the invention allows for a relatively low cost and simple process for the preparation of a PVOH film which exhibits the aforementioned benefits. As such, the invention is a favourable alternative to known processes for preparing a PVOH film, such as blown extrusion which encompasses complex and difficult to control process steps and relatively high cost, typically due to the multiple thermal stress steps and high shear forces required in the blown extrusion process.

[0022] Further advantageously, the invention provides for a PVOH film with a greater thermal stretch property. As such, the film formed by the invention exhibits a homogenous stretch which, beneficially, means that the prepared film is easier to deform into moulds with greater complexity. Thus, the film prepared by the invention may be used to form complex articles, such as multiple compartment ADW pouches.

[0023] The term ‘water-soluble’ is used herein to refer to a material which and at least partially dissolves or disperses in water at 20 °C within 10 minutes. The term ‘water- PAT 15669- WO-PCT

[0024] 4 soluble package’ is used herein to refer to a package which at least partially disperses, disintegrates or ruptures in water at 20 °C within 10 minutes to allow for egress of the contents of the package into the surrounding water.

[0025] The term ‘heat transfer roller’ is used herein to refer to a rotatable roller, typically a chrome plated or stainless-steel roller, onto which a composition is extruded in the preparation of a water-soluble film. In use, the heat transfer roller is heated or cooled to a predetermined temperature. Heat transfer rollers are known in the art and typically comprise an inner shell and an outer shell. Typically, a fluid heated to a required temperature is injected at a first end of the roller and is passed between the inner shell and outer shell, before being ejected from a second end, opposite the first end, of the roller. The inner shell may comprise a plurality of baffles to facilitate distribution of the fluid between the inner shell and outer shell, to provide enhanced temperature control and heat distribution across the roller.

[0026] The first heat transfer roller may have a temperature of at least about 20°C, about 30°C, about 40°C, or at least about 50°C.

[0027] The first heat transfer roller may have a temperature of no more than about 60°C, about 70°C, or no more than about 90°C.

[0028] In one embodiment, the first heat transfer roller has a temperature of from 30°C to 90°C, preferably from 30°C to 50°C or from 50°C to 70°C.

[0029] Advantageously, in embodiments of the invention comprising a first heat transfer roller having a temperature of from about 22°C to about 90°C, in particular from about 30°C to about 90°C, the invention provides for greater control of the thickness of the PVOH film prepared by the invention. This beneficial effect is further enhanced in embodiments comprising a first heat transfer roller having a temperature of from about 50°C to about 70°C.

[0030] In particular, in embodiments of the invention comprising a first heat transfer roller having a temperature of from about 30°C to about 90°C, the process provides for significant control of preparing PVOH films having a thickness of greater than 50pm, for example from about 50pm to about 200pm, in particular from about 80pm to about 100pm, such as about 90pm. PAT 15669- WO-PCT

[0031] 5

[0032] Further advantageously, in embodiments of the invention comprising a first heat transfer roller having a temperature of from about 22°C to about 90°C, in particular from about 30°C to about 90°C, more particularly from about 60°C to about 90°C, the invention provides for even greater control over the thermal stretch property of the prepared PVOH film. Achieving greater control over the thermal stretch of a prepared film means that a homogenous stretch of the film may be obtained, i.e., the film stretches more equally in a machine direction and in a transverse direction.

[0033] Advantageously, the film is, therefore, more easily deformed into a mold. As such, the film may be more easily deformed into moulds with greater complexity. Such films are, therefore, more favourably used to form complex articles, such as multiple compartment ADW pouches.

[0034] The second heat transfer roller may have any temperature which is less than the temperature of the first heat transfer roller.

[0035] The second heat transfer roller may have a temperature which is at least 5°C, 10°C, 15°C, 20°C, 30°C or 40°C less than the temperature of the first heat transfer roller.

[0036] In one embodiment, the second heat transfer roller has a temperature of from 20°C to 50°C, preferably from 20°C to 40°C.

[0037] The at least one PVOH resin may comprise a first PVOH resin.

[0038] The first PVOH resin may have a degree of hydrolysis of from about 87.0 mol.% to about 89.0 mol.%, from about 87.2 mol.% to about 88.8 mol.%, from about 87.4 mol.% to about 88.6 mol.%, from about 87.6 mol.% to about 88.4 mol.%, from about 87.8 mol.% to about 88.2 mol.%, or about 88.0 mol.%.

[0039] Beneficially, in embodiments comprising a first PVOH resin having a degree of hydrolysis of from about 87.0 mol.% to about 89.0 mol.%, the composition has an improved dissolution characteristic. As used herein, the degree of hydrolysis is expressed as a percentage of vinyl acetate units converted to vinyl alcohol units.

[0040] In one embodiment, the first PVOH resin may have a weight average molecular weight of from about 50,000 g / mol to about 150,000 g / mol, preferably from about PAT 15669- WO-PCT

[0041] 6

[0042] 70,000 g / mol to about 120,000 g / mol, and more preferably from about 80,000 g / mol to about 100,000 g / mol.

[0043] Beneficially, in embodiments comprising a first PVOH resin having a weight average molecular weight of at least about 50,000 g / mol, in particular, about 50,000 g / mol to about 150,000 g / mol, ensures a suitable mechanical stability during the heatsealing process.

[0044] All weight average molecular weights described herein are determined by gel permeation chromatography.

[0045] The first PVOH resin has a viscosity ranging from 5 to 30 mPa s of 4 wt.% aqueous solution at 20°C, preferably a viscosity ranging from 7 to 24 mPa s of 4 wt.% aqueous solution at 20°C, and more preferably a viscosity ranging from 9 to 18 mPa s of 4 wt.% aqueous solution at 20°C.

[0046] The at least one PVOH resin may comprise a second PVOH resin.

[0047] The second PVOH resin may have a degree of hydrolysis of from about 87.0 mol.% to about 89.0 mol.%, from about 87.2 mol.% to about 88.8 mol.%, from about 87.4 mol.% to about 88.6 mol.%, from about 87.6 mol.% to about 88.4 mol.%, from about 87.8 mol.% to about 88.2 mol.%, or about 88.0 mol.%.

[0048] Beneficially, in embodiments comprising a second PVOH resin having a degree of hydrolysis of from about 87.0 mol.% to about 89.0 mol.%, the composition has an improved dissolution characteristic.

[0049] The second PVOH resin may have a weight average molecular weight of at most about 50,000 g / mol.

[0050] The second PVOH resin may have a weight average molecular weight of from about 10,000 g / mol to about 50,000 g / mol, preferably from about 20,000 g / mol to about 50,000 g / mol, and more preferably from about 35,000 g / mol to about 50,000 g / mol.

[0051] Advantageously, in embodiments comprising a second PVOH resin having a weight average molecular weight of at most about 50,000 g / mol, for example from about 35,000 g / mol to about 50,000 g / mol, the resin enables a reduction in the melt PAT 15669- WO-PCT

[0052] 7 viscosity and provides even more favourable elastic properties, in addition to a further increased robustness suitable for the thermal sealing process.

[0053] The second PVOH resin may have a viscosity of at most 7.0 mPa s of 4 wt.% aqueous solution at 20°C. The second PVOH resin has preferably a viscosity ranging from 1 to 7 mPa s of 4 wt.% aqueous solution at 20°C, more preferably a viscosity ranging from 2.5 to 7 mPa s of 4 wt.% aqueous solution at 20°C, and most preferably a viscosity ranging from 3.5 to 6.5 mPa s of 4 wt.% aqueous solution at 20°C.

[0054] Step (b) may be carried out after step (a).

[0055] The process may further comprise, before step (a), a step of adding the composition comprising the at least one PVOH resin into an extruder.

[0056] The extruder may be, for example, a single or twin-screw extruder

[0057] The process may further comprise, before step (a), a step of adding at least one plasticiser into the extruder, such that the composition comprises at least one plasticiser.

[0058] The at least one plasticiser may be a liquid plasticiser at room or ambient temperature. For example, the at least one plasticiser may be a liquid at about 20-25°C.

[0059] By ‘liquid at room or ambient temperature’ it is meant that the melting point of the plasticiser at a pressure of 1 atmosphere is less than or equal to about 20-25°C.

[0060] Beneficially, the use of a liquid plasticiser improves the forming properties and sealing strength of the resulting films.

[0061] The at least one plasticiser may be present in the composition in an amount of from 15 to 35 wt.%, from 18 to 28 wt.%, from 20 to 25 wt.%, or 25 wt.%.

[0062] The at least one plasticiser may be selected from the group consisting of glycerine and derivatives thereof, a C2-C6 alkylene glycol and derivatives thereof, polyalkylene glycols, esters of carboxylic acids, or any combinations thereof.

[0063] Examples of C2-C6 alkylene glycols suitable for use in the present invention include but are not limited to ethylene glycol, 1,2 propylene glycol, 1,3 propylene glycol, butylene glycol, pentylene glycol, and hexylene glycol. Examples of polyalkylene glycols include but are not limited to polyethylene glycol, and polypropylene glycol. PAT 15669- WO-PCT

[0064] 8

[0065] Examples of esters of carboxylic acids include but are not limited to esters of citric acid, malic acid, maleic acid or succinic acid.

[0066] The composition may comprise more than one plasticiser, for example the composition may comprise a blend of plasticisers.

[0067] Advantageously, in embodiments comprising more than one plasticiser, for example a blend of plasticisers, in particular a blend of glycerine and an alkylene glycol (such as 1,2-propylene glycol), the sealing strength of the film is increased. Without being bound by theory, this may be due to the interaction of the polyvinyl alcohol hydroxyl groups with the different molecular sizes of plasticiser.

[0068] The ratio of the blend of plasticisers, such as a blend of glycerine and 1,2- propylene glycol, may be from 1:1 to 8:1, such as between 2:1 and 6:1, for example 4:1.

[0069] The plasticiser may be a plasticiser which is solid at room or ambient temperature.

[0070] By "solid at room or ambient temperature" it is meant that the melting point of the plasticiser at a pressure of 1 atmosphere is greater than about 20-25 °C.

[0071] Suitable solid plasticisers are solid or waxy at ambient temperature. Suitable solid plasticisers include solid polyols and other carbohydrates. Suitable solid polyols include sugar alcohols such as sorbitol, glucitol, mannitol, galactitol, dulcitol, xylitol, erythritol, pentaerythritol, isomaltose and isomalt.

[0072] The process may further comprise, before step (a), a step of adding at least one processing aid into the extruder, such that the composition comprises a processing aid.

[0073] Suitable processing aids include mono-, di-, tri-carboxylic acids / salts thereof, fatty acids such as stearic acid / salts thereof, mono-, di- or triglycerides / salts thereof, fumed silica and inorganic and organic pigments.

[0074] The at least one processing aid may be present in the composition in an amount of from about 0.5 wt.% to about 5.0 wt.%, from about 0.5 wt.% to about 4.5 wt.%, from about 0.5 wt.% to about 4.0 wt.%, from about 0.5 wt.% to about 3.5 wt.%, from about 0.5 wt.% to about 3.0 wt.%, from about 0.5 wt.% to about 2.5 wt.%, from about 0.5 PAT 15669- WO-PCT

[0075] 9 wt.% to about 2.0 wt.%, from about 0.5 wt.% to about 1.5 wt.%, or from about 0.5 wt.% to about 1.0 wt.%.

[0076] The composition may comprise more than one processing aid, for example the composition may comprise a blend of processing aids.

[0077] The composition, which may comprise a plasticiser and / or processing aid in addition to at least one PVOH resin, may be heated in the extruder to a melt temperature of from about 180°C to about 210°C to melt the components of the composition into a liquid composition. The melt temperature may be from about 185°C to about 205°C, from about 190°C to about 205°C, from about 190°C to about 200°C, or about 195°C.

[0078] The total amount of PVOH resin in the composition may be from 50 - 90 wt.%.

[0079] Advantageously, embodiments of the invention comprising a single PVOH resin in an amount of from about 60 wt.% to about 90 wt.%, a temperature of the first heat transfer roller of from about 20°C to about 90°C, in particular of from about 20°C to about 70°C, more particular of from about 40°C to about 70°C, and most particular of about 50°C to 70°C, prepares a PVOH film having most favourable thermoformability properties. The thermoformability is further enhanced in embodiments of the invention comprising a single PVOH resin having a degree of hydrolysis of about 87.0 to about 89.0 mol.%. The thermoformability is even further enhanced in embodiments of the invention comprising a single PVOH resin having a viscosity of from about 7.0 mPa- s of 4 wt.% aqueous solution at 20°C to about 15 mPa- s of 4 wt.% aqueous solution at 20°C, and values and ranges therebetween, as defined above. The thermoformability is even further enhanced in embodiments of the invention comprising a single PVOH resin having a weight average molecular weight of from about 70,000 g / mol to about 100,000 g / mol, and values and ranges therebetween, as defined above.

[0080] In some embodiments comprising a first PVOH resin and a second PVOH resin, the first PVOH resin may be present in the composition in an amount of from 50 - 90 wt.%, from 50 - 80 wt.%, or from 50 - 65 wt.%. PAT 15669- WO-PCT

[0081] 10

[0082] In some embodiments comprising a first PVOH resin and a second PVOH resin, the second PVOH resin may be present in an amount of from 10 - 40 wt.%, from 15 - 35 wt.%, or from 15 - 25 wt.%.

[0083] Advantageously, embodiments of the invention comprising two PVOH resins in a total amount of from about 60 wt.% to about 90 wt.%, a temperature of the first heat transfer roller of from about 20°C to about 90°C, in particular of from about 30°C to about 70°C, more particular of from about 40°C to about 70°C, and most particular of from about 50°C to 70°C, prepares a PVOH film having most favourable thermoformability properties. The thermoformability is further enhanced in embodiments of the invention comprising two PVOH resins, each resin having a degree of hydrolysis of about 87.0 to about 89.0 mol.%.

[0084] The composition may further comprise an anti-blocking agent may also be present in the film. Suitable anti-blocking agents include silica, talcum, zeolites, calcium carbonate and starch.

[0085] The composition may be extruded through the extruder through a die and onto the first heat transfer roller to form a film.

[0086] In one embodiment, the die is a flat die having a die gap of from 200 - 1500pm, preferably of from 400 - 1500pm, and more preferably of from 600 - 1500pm.

[0087] Step (a) may further comprise extruding the composition comprising the at least one PVOH resin through a flat die and onto the first heat transfer roller.

[0088] The process may further comprise, after step (b), the following step:

[0089] (c) forming a film comprising the composition comprising the at least one PVOH resin.

[0090] The film may be cast to a thickness of from 50 - 200pm, 50 - 150pm, 50 - 120pm, or from 50 - 60pm; preferably to a thickness of from 80 - 100pm.

[0091] Beneficially, a film formed by the invention and being cast to a thickness of from 50pm to 200pm, is able to be readily deformed, thus allowing the film to find particular applicability in forming complex pouch designs which comprise multiple compartments, such as ADW pouches. PAT 15669- WO-PCT

[0092] 11

[0093] Advantageously, a PVOH film formed by the invention may readily be cast to a homogenous thickness.

[0094] According to a second aspect of the invention, there is provided a thermoformed package for an automatic dishwashing cycle, wherein the thermoformed package comprises at least one PVOH film prepared according to the process of the first aspect.

[0095] The invention according to the second aspect may optionally include any of the features of the invention according to any other aspect.

[0096] The package may be added to the automatic dishwashing machine at the start of a main wash cycle or at the start of a pre-wash cycle. The package may be added to a dosing basket or a dosing chamber within the automatic dishwashing machine. The package may be placed on a floor of the automatic dishwashing machine.

[0097] The package may comprise a dosing format which releases an at least one solid detergent composition and an at least one gel detergent composition over a plurality of stages of a dishwashing cycle or over at least one stage of a plurality of dishwashing cycles. In embodiments comprising a package comprising at least one liquid detergent composition, the at least one liquid detergent composition may be released over a plurality of stages of a dishwashing cycle or over at least one stage of a plurality of dishwashing cycles.

[0098] The package may comprise a first PVOH film, prepared according to the invention, comprising a pocket and a surrounding flange, and a second PVOH film, prepared according to the invention, applied as a cover across the pocket and sealed across the flange. The package may comprise a first PVOH film, prepared according to the invention, comprising more than one pocket, for example a number of pockets selected from the group comprising two or more, three or more, four or more, five or more, or six or more pockets, and a surrounding flange, and a second PVOH film, prepared according to the invention, applied as a cover across each pocket and sealed across the flange. In some embodiments there are three or four pockets.

[0099] The package may be in a unit-dose format.

[0100] By ‘unit-dose’, it is meant that the package comprises at least one solid detergent composition and at least one gel detergent composition, together in the PAT 15669- WO-PCT

[0101] 12 quantity required for a single wash cycle of a machine dishwasher. In some embodiments the unit dose format also includes a liquid detergent composition.

[0102] The package may comprise a multi-cycles device; that is, the device may be structured to release the detergent compositions comprised in the package across multiple cycles of washing, and may either be added to a dishwasher and left for multiple cycles or may be removed and replaced for each cycle. The multi-cycles device may comprise a plurality of doses of the at least one solid detergent composition and the at least one gel detergent composition of the package. The plurality of doses may be arranged to release one dose at any defined time period, such as once every wash cycles, once every stage in every wash cycle or at two or more stages in every wash cycle, for example.

[0103] The or each compartment may be completely filled with a detergent composition. Partial filling of each compartment may reduce the risk of rupture of the package, if the package is subjected to shock, and may reduce the risk of leakage if the package is subject to high temperatures.

[0104] The thermoformed package may comprise a first compartment comprising a solid detergent composition, a liquid detergent composition or a gel detergent composition. The thermoformed package may comprise a second compartment comprising a solid detergent composition, a liquid detergent composition or a gel detergent composition. The thermoformed package may comprise a third compartment comprising a solid detergent composition, a liquid detergent composition or a gel detergent composition.

[0105] In some embodiments, the thermoformed package may comprise a first compartment comprising a solid detergent composition, a second compartment comprising a gel detergent composition, and a third compartment comprising a liquid detergent composition.

[0106] Each compartment may have a volume which is the same as one or more other compartments; or may have a volume which is different to each other compartment. PAT 15669- WO-PCT

[0107] 13

[0108] Detailed Description of the Invention

[0109] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0110] Figure 1 shows an embodiment of the invention for preparing a polyvinyl film, and

[0111] Figure 2 shows multiple compartments of an example of a package formed using a PVOH film prepared according to an embodiment of the invention.

[0112] With reference to Figure 1, there is shown an embodiment of the invention for preparing a polyvinyl film.

[0113] All solid parts of a first inventive composition, such as a first polyvinyl alcohol (PVOH) resin and the processing aids are added to a hopper 1. The first PVOH resin may be a solid and may be added to the hopper as a plurality of granules. The first PVOH resin may have a degree of hydrolysis of between about 87.0 mol.% and about 89.0 mol.%, specifically about 88.0 mol%. The first PVOH resin may also have a viscosity of between about 8.0 and about 10.0 mPa s of 4 wt.% aqueous solution at 20°C, specifically about 9.0 mPa s of 4 wt.% aqueous solution at 20°C. The first PVOH resin may also have a weight average molecular weight of about 72,200 g / mol.

[0114] All liquid parts of said composition being preferably comprised, such as plasticizers, in particular glycerine is added subsequently to the extruder via a liquid dosing means 11.

[0115] The first PVOH resin may be present in the composition in an amount of 73.8 wt.%, based on the total weight of the composition. The composition of the presently described embodiment comprises a single PVOH resin.

[0116] Glycerine may be present in the composition in an amount of 25.0 wt.%, based on the total weight of the composition.

[0117] The processing aid may be present in the composition in an amount of 1.2 wt.%, based on the total weight of the composition. PAT 15669- WO-PCT

[0118] 14

[0119] From the hopper 1, all solid parts of the first inventive composition, namely the at least first PVOH resin and optionally solid processing aids or solid plasticizers (such as Sorbitol) then enter an extruder 2, preferably as a plurality of granules. The extruder 2 may be a twin-screw extruder 2. After the plurality of granules have been mixed and further crushed in a first zone of the extruder, all liquid parts of the first inventive composition, such as glycerine, were subsequently added via a liquid dosing means 11 to a subsequently arranged second zone of the extruder in which all solid and liquid parts of the first inventive composition were mixed and finally heated to a melt temperature of from about 185°C to about 205°C to melt all the components of the first inventive composition into a liquid composition. The liquid composition may then be fed, with a melt pump (not shown), to a flat die 3. The liquid composition may be extruded upon a first heat transfer roller 6 comprising a chrome-plated rotating roller, and is formed as a cast film 5 upon the first heat transfer roller 6.

[0120] The first heat transfer roller 6 may have a temperature of between about 30°C and about 90°C, more specifically between about 50°C and about 70°C.

[0121] The cast film 5 may then be fed from upon the first heat transfer roller 6 to a second heat transfer roller 7 comprising a chrome-plated rotating roller, and which has a temperature less than the temperature of the first heat transfer roller 6. The second heat transfer roller 7 may have a temperature of from about 20°C to about 40°C, more specifically of from about 20°C to about 30°C.

[0122] The cast film 5 may then be transferred to subsequent roller 8a, then roller 8b, followed by roller 8c, 8d, 8e and finally 8f.

[0123] The film 5 may be set to a desired width by trimmer 9 before being collected as a wound film 10 upon a winding system.

[0124] Advantageously, the wound film 10 exhibits improved mechanical properties, for example thermoformability, compared to films, in particular PVOH films, produced by other processes and, in particular, produced by known film manufacturing methods, for example aqueous solution casting. The wound film 10 possesses a higher sealing strength and better thermoforming properties compared to PVOH films formed by known film manufacturing methods, for example aqueous solution casting. PAT 15669- WO-PCT

[0125] 15

[0126] Beneficially, the process of the invention benefits from the advantages of cast extrusion processes (for example, low energy demand and, therefore, low cost) while providing a PVOH film which exhibits advantageous mechanical properties which are not found in PVOH films produced by known film manufacturing methods, for example aqueous solution casting.

[0127] Further advantageously, the enhanced thermoformability of the wound film 10 means that the film 10 can be readily used to create monodose articles, such as ADW pouches, and complex articles such as complex pouch designs which comprise multiple compartments.

[0128] Even further advantageously, the invention provides for a relatively low cost and simple process for the preparation of a PVOH film which exhibits the aforementioned benefits. As such, the invention is a favourable alternative to known processes for preparing a PVOH film, such as blown extrusion which encompasses complex and difficult to control process steps and relatively high cost, typically due to the multiple thermal stress steps and high shear forces required in the blown extrusion process.

[0129] With reference to Fig. 2, there is shown an example of a multicompartment ADW package formed using a PVOH film prepared according to an embodiment of the invention. An outer flange, or rim, of the package is not shown in Fig. 2.

[0130] The package is prepared by a process comprising thermoforming a first PVOH film prepared according to an embodiment of the invention described in relation to Fig. 1, to produce three separate compartments 100, 200, 300. The thermoforming step may include applying heat (about 130°C) and a vacuum (about 490 mbar) to the film when placed in a corresponding mold.

[0131] Prior to use, the first compartment 100 may be at least partially filled with a powdered detergent composition, the second compartment 200 may be at least partially filled with a gel detergent composition, and the third compartment 300 may be at least partially filled with a liquid detergent composition.

[0132] A second PVOH film, preferably a PVOH film prepared according to an embodiment of the invention described in relation to Fig. 1, may then be placed upon PAT 15669- WO-PCT

[0133] 16 the first thermoformed PVOH film such that the second PVOH film overlies the first compartment 100, second compartment 200 and third compartment 300.

[0134] The first PVOH film and the second PVOH film are then heat sealed together about a peripheral flange (not shown) to enclose each respective detergent composition within each compartment 100, 200, 300. The package forms a substantially square shape (when viewed in plan view as in Fig. 2) and has a length of about 4cm and a width of about 4cm.

[0135] In an alternative embodiment, a second inventive composition comprising a first polyvinyl alcohol (PVOH) resin and a second PVOH resin is added to a hopper 1.

[0136] Herein, all solid parts of said second inventive composition, such as the first PVOH resin, the second PVOH resin and the processing aids are added to the hopper 1 as a plurality of granules.

[0137] The first PVOH resin may have a degree of hydrolysis of between about 87.0 mol.% and about 89.0 mol.%, specifically about 88.0 mol%. The first PVOH resin may also have a viscosity of between about 15.0 and about 19.0 mPa s of 4 wt.% aqueous solution at 20°C, specifically about 17.0 mPa s of 4 wt.% aqueous solution at 20°C. The first PVOH resin may also have a weight average molecular weight of about 100,000 g / mol.

[0138] The second PVOH resin may have a degree of hydrolysis of between about 87.0 mol.% and about 89.0 mol.%, specifically about 88.0 mol%. The second PVOH resin may also have a viscosity of between about 4.0 and about 6.0 mPa s of 4 wt.% aqueous solution at 20°C, specifically about 5.0 mPa s of 4 wt.% aqueous solution at 20°C. The second PVOH resin may also have a weight average molecular weight of about 39,900 g / mol.

[0139] All liquid parts of said composition being preferably comprised, such as plasticizers, in particular glycerine is added subsequently to the extruder via a liquid dosing means 11.

[0140] The second PVOH resin may be present in the composition in an amount of 19.6 wt.%, based on the total weight of the composition. The first PVOH resin may be present in the composition in an amount of 54.2 wt.%, based on the total weight of the PAT 15669- WO-PCT

[0141] 17 composition. The composition of the presently described embodiment comprises two PVOH resins.

[0142] Glycerine may be present in the composition in an amount of 25.0 wt.%, based on the total weight of the composition.

[0143] The processing aid may be present in the composition in an amount of 1.2 wt.%, based on the total weight of the composition.

[0144] From the hopper 1, all solid parts of the first inventive composition, namely the at least first and second PVOH resin and optionally solid processing aids or solid plasticizers (such as Sorbitol) then enter an extruder 2, preferably as a plurality of granules. The extruder 2 may be a twin-screw extruder 2. After the plurality of granules have been mixed and further crushed in a first zone of the extruder, all liquid parts of the second inventive composition, such as glycerine, were subsequently added via a liquid dosing means 11 to a subsequently arranged second zone of the extruder in which all solid and liquid parts of the second inventive composition were mixed and finally heated to a melt temperature of from about 185°C to about 205°C to melt all the components of the first inventive composition into a liquid composition. The liquid composition may then be fed, with a melt pump (not shown), to a flat die 3. The liquid composition may be extruded upon a first heat transfer roller 6 comprising a chrome- plated rotating roller, and is formed as a cast film 5 upon the first heat transfer roller 6.

[0145] The first heat transfer roller 6 may have a temperature of between about 30°C and about 90°C, more specifically about 50°C to 70°C.

[0146] The cast film 5 may then be fed from upon the first heat transfer roller 6 to a second heat transfer roller 7 comprising a chrome-plated rotating roller, and which has a temperature less than the temperature of the first heat transfer roller 6. The second heat transfer roller 7 may have a temperature of from about 20°C to about 40°C, more specifically from about 20°C to about 30°C.

[0147] Each of the first heat transfer roller 6 and second heat transfer roller 7 may have a rotation speed of approximately 4 metres / minute to 30m / min. PAT 15669- WO-PCT

[0148] 18

[0149] The cast film 5 may then be transferred to subsequent roller 8a, then roller 8b, followed by roller 8c, 8d, 8e and finally 8f.

[0150] The film 5 may be set to a desired width by trimmer 9 before being collected as a wound film 10 upon a winding system.

[0151] Advantageously, the wound film 10 exhibits improved mechanical properties, for example thermoformability, compared to films, in particular PVOH films, produced by other processes and, in particular, produced by known film manufacturing methods, for example aqueous solution casting. The wound film 10 possesses a higher sealing strength and better thermoforming properties compared to PVOH films formed by known film manufacturing methods, for example aqueous solution casting.

[0152] Beneficially, the process of the invention benefits from the advantages of cast extrusion processes (for example, low energy demand and, therefore, low cost) while providing a PVOH film which exhibits advantageous mechanical properties which are not found in PVOH films produced by known film manufacturing methods, for example aqueous solution casting.

[0153] Further advantageously, the enhanced thermoformability of the wound film 10 means that the film 10 can be readily used to create monodose articles, such as ADW pouches, and complex articles such as complex pouch designs which comprise multiple compartments.

[0154] Even further advantageously, the invention provides for a relatively low cost and simple process for the preparation of a PVOH film which exhibits the aforementioned benefits. As such, the invention is a favourable alternative to known processes for preparing a PVOH film, such as blown extrusion which encompasses complex and difficult to control process steps and relatively high cost, typically due to the multiple thermal stress steps and high shear forces required in the blown extrusion process. PAT 15669- WO-PCT

[0155] 19

[0156] EXAMPLES

[0157] Forming Assessment 1

[0158] A composition, Composition (1), was prepared according to the following:

[0159] Composition (1):

[0160] Composition (1) comprised a single PVOH resin (1) having a degree of hydrolysis of 88.0 mo.%, a viscosity of 9.0 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 72,200 g / mol.

[0161] A PVOH film was prepared using Composition (1) and according to the inventive process of the invention as described before in the description for the first inventive composition. Herein, the PVOH resin and the processing aids are added as solid parts while glycerine had been subsequently added as a liquid component via the above-described liquid dosing means. The film was produced using a Collin ZK 25*42D twin-screw extruder (diameter: 25mm, [L / D] = 42, length = 1050mm, Screw speed 300-600 rpm). The Composition (1) was melted in the extruder at a temperature of 185°C. The melted composition was then fed with a melt pump to a flat die for extrusion at a speed of 9 kg / h. The composition was extruded onto two heat transfer rollers, i.e., a first heat transfer roller and a second heat transfer roller, to form a film. PAT 15669- WO-PCT

[0162] 20

[0163] The forming assessment was repeated to provide five examples of the inventive process of the invention. Each Inventive Process differed in respect of the temperature of the first heat transfer roller used to prepare the film.

[0164] In Inventive Process 1, the first heat transfer roller had a temperature of 30°C.

[0165] In Inventive Process 2, the first heat transfer roller had a temperature of 40°C.

[0166] In Inventive Process 3, the first heat transfer roller had a temperature of 50°C.

[0167] In Inventive Process 4, the first heat transfer roller had a temperature of 60°C.

[0168] In Inventive Process 5, the first heat transfer roller had a temperature of 90°C.

[0169] In each of Inventive Processes 1-5, the second heat transfer roller had a temperature of 20°C.

[0170] In each Inventive Process, the PVOH film was cast to a thickness of 90pm and collected via a winding system.

[0171] In each Inventive Process, the PVOH film was prepared using Composition (1).

[0172] The Forming Assessment was carried out by placing a PVOH film prepared according to the aforementioned Inventive Process and comprising Composition (1) on a thermoforming kit with a mold having three individual cavities. As shown in Fig. 2, cavities 100, 200, 300 were formed in each film through the application of heat (130°C) and a vacuum (490 mbar) to the film. Prior to use as an ADW package, the first cavity 100 may be at least partially filled with a powdered detergent composition, the second cavity 200 may be at least partially filled with a gel detergent composition, and the third cavity 300 may be at least partially filled with a liquid detergent composition.

[0173] Each film was thermoformed into the desired shape and a visual assessment by a trained evaluator is used to evaluate the forming behaviour.

[0174] A visual assessment was carried out for each individual cavity 100, 200, 300. Each cavity 100, 200, 300 was scored according to a scale where:

[0175] 0 = best forming behaviour, i.e., complete forming of the compartment shape is observed PAT 15669- WO-PCT

[0176] 21

[0177] 8 = worst forming behaviour, i.e., no forming of the compartment shape is observed

[0178] Results: Composition (1)

[0179] Notably, the results show an improved thermoformability with increasing the temperature of the first heat transfer roller up to 50°C. Inventive Processes 4 and 5, did not show further improvement in thermoformability with increasing the temperature of the first heat transfer roller to 60°C and 90°C, respectively, compared to that of Inventive Process 3.

[0180] This shows that, advantageously, the cast extrusion process of the invention provides for a PVOH film which exhibits favourable mechanical properties, for example thermoformability, which are not found in PV OH films prepared by known film manufacturing methods, for example aqueous solution casting. Moreover, it is advantageous that the thermoformability property of the PVOH films prepared by the invention is provided by a cast extrusion process and not by a blown extrusion process PAT 15669- WO-PCT

[0181] 22 which is relatively more energy consuming, higher in cost and greater in complexity. The favourable thermoformability of the prepared PVOH films means that such films are easier to deform into moulds with greater complexity. Such films can, therefore, be used to form complex articles, such as multiple compartment ADW pouches.

[0182] Thus, it is advantageous that the invention provides a PVOH film which is formed using a relatively cheap, low energy and simple process, but which exhibits favourable thermoformability properties as may be found in PVOH films produced by relatively expensive, high energy and complex processes of the prior art.

[0183] As such, surprisingly, advantageous results may be obtained by a cast extrusion process for preparing a PVOH film, wherein the process comprises extruding a PVOH composition comprising a single PVOH resin onto a first heat transfer roller having a temperature of from 20°C to 90°C, and then feeding the composition onto a second heat transfer roller which has a temperature less than the first heat transfer roller.

[0184] Forming Assessment 2

[0185] A composition, Composition (2), was prepared according to the following:

[0186] Composition (2):

[0187] Composition (2) comprised a two PVOH resins, PVOH resin (2) and PVOH resin (3).

[0188] PVOH resin (2) had a degree of hydrolysis of 88.0 mo%, a viscosity of 5.0 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 39,900 g / mol.

[0189] PVOH resin (3) had a degree of hydrolysis of 88.0 mo.%, a viscosity of 17.0 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 100,000 g / mol. PAT 15669- WO-PCT

[0190] 23

[0191] A PVOH film was prepared using Composition (2) and according to the inventive process of the invention as described before in the description for the second inventive composition. Herein, the PVOH resins (2) and (3) and the processing aids are added as solid parts while glycerine had been subsequently added as a liquid component via the above-described liquid dosing means.. The film was produced using a Collin ZK 25*42D twin-screw extruder (diameter: 25mm, [L / D] = 42, length = 1050mm, Screw speed 300-600 rpm). The Composition (2) was melted in the extruder at a temperature of 185°C. The melted composition was then fed with a melt pump to a flat die for extrusion at a speed of 9 kg / h. The composition was extruded onto two heat transfer rollers, i.e., a first heat transfer roller and a second heat transfer roller, to form a film.

[0192] The forming assessment was repeated to provide five examples of the inventive process of the invention. Each Inventive Process differed in respect of the temperature of the first heat transfer roller used to prepare the film.

[0193] In Inventive Process 6, the first heat transfer roller had a temperature of 30°C.

[0194] In Inventive Process 7, the first heat transfer roller had a temperature of 40°C.

[0195] In Inventive Process 8, the first heat transfer roller had a temperature of 50°C.

[0196] In Inventive Process 9, the first heat transfer roller had a temperature of 60°C.

[0197] In Inventive Process 10, the first heat transfer roller had a temperature of 90°C.

[0198] In each of Inventive Processes 6-10, the second heat transfer roller had a temperature of 20°C.

[0199] In each Inventive Process, the PVOH film was cast to a thickness of 90pm and collected via a winding system.

[0200] In each Inventive Process, the PVOH film was prepared using Composition (2). PAT 15669- WO-PCT

[0201] 24

[0202] The Forming Assessment was carried out by placing a PVOH film prepared according to the aforementioned Inventive Process and comprising Composition (2) on a thermoforming kit with a mold having three individual cavities. As shown in Fig. 2, cavities 100, 200, 300 were formed in each film through the application of heat (130°C) and a vacuum (490 mbar) to the film. Prior to use as an ADW package, the first cavity 100 may be at least partially filled with a powdered detergent composition, the second cavity 200 may be at least partially filled with a gel detergent composition, and the third cavity 300 may be at least partially filled with a liquid detergent composition.

[0203] Each film was thermoformed into the desired shape and a visual assessment by a trained evaluator is used to evaluate the forming behaviour.

[0204] A visual assessment was carried out for each individual cavity 100, 200, 300. Each cavity 100, 200, 300 was scored according to a scale where:

[0205] 0 = best forming behaviour, i.e., complete forming of the compartment shape is observed 8 = worst forming behaviour, i.e., no forming of the compartment shape is observed

[0206] Results: Composition (2) PAT 15669- WO-PCT

[0207] 25

[0208] Surprisingly, the Forming Assessment results of a film comprising Composition (2) and prepared according to Inventive Processes 6-10 shows comparably advantageous results to that of films comprising Composition (1) and prepared according to Inventive Processes 1-5.

[0209] Notably, thermoformability of the prepared films increases with increasing temperature of the first heat transfer roller. While favourable results are achieved using each Inventive Process 6-10, further improved thermoformability is found from Inventive Process 6 to Inventive Process 9. Inventive Process 10 shows that increasing the temperature of the first heat transfer roller to 90°C maintains the advantageous thermoformability property of the films prepared at lower first heat transfer roller temperatures (i.e., Inventive Process 9).

[0210] This shows that, advantageously, the cast extrusion process of the invention provides for a PVOH film which exhibits favourable mechanical properties, for example thermoformability, which are not found in PVOH films prepared by known film manufacturing methods, for example aqueous solution casting. Moreover, it is advantageous that the thermoformability property of the PVOH films prepared by the invention is provided by a cast extrusion process and not by a blown extrusion process which is relatively more energy consuming, higher in cost and greater in complexity. The favourable thermoformability of the prepared PVOH films means that such films are easier to deform into moulds with greater complexity. Such films can, therefore, be used to form complex articles, such as multiple compartment ADW pouches.

[0211] Thus, it is advantageous that the invention provides a PVOH film which is formed using a relatively cheap, low energy and simple process, but which exhibits favourable thermoformability properties as may be found in PVOH films produced by relatively expensive, high energy and complex processes of the prior art.

[0212] As such, surprisingly, advantageous results may be obtained by a cast extrusion process for preparing a PVOH film, wherein the process comprises extruding a PVOH composition comprising two PVOH resins onto a first heat transfer roller having a temperature of from 20°C to 90°C, and then feeding the composition onto a second heat transfer roller which has a temperature less than the first heat transfer roller. PAT 15669- WO-PCT

[0213] 26

[0214] Thermal Stretch Property Assessment

[0215] Composition (2)

[0216] The thermal stretch property of the two films comprising Composition (2) and prepared according to Inventive Processes 9 and 10 was assessed. Each film was prepared as described above in relation to the Forming Assessment of Composition (2).

[0217] The thermal stretch was assessed according to the following method and using aZwicki-Line testing machine Z1.0 operated by a trained evaluator.

[0218] Two films prepared according to Inventive Processes 9 and 10, respectively, were heated to 120°C and maintained at this temperature for the duration of the assessment. A tensile force of 2.5 N or 5 N was applied to each respective film by the Zwicki-Line testing machine Z 1.0 until there was no further elongation of the respective film.

[0219] The elongation of both Machine Direction (MD) and Transverse Direction (TD) of the respective films was assessed, and the ratio of TD:MD calculated such that a ratio of 1 suggests that the film exhibits a most favourable homogenous stretch.

[0220] A film exhibiting a homogenous stretch means that the film is more easily deformed into a mold. As such, the film may be more easily deformed into moulds with greater complexity. Such films are, therefore, more favourably used to form complex articles, such as multiple compartment ADW pouches.

[0221] Results: Composition (2) PAT 15669- WO-PCT

[0222] 27

[0223] It is shown that films formed by both Inventive Process 9 and Inventive Process 10 exhibit favourably comparable thermal stretch properties.

[0224] Notably, Inventive Process 9 provides for a film with slightly more favourable thermal stretch property than a film prepared by Inventive Process 10.

[0225] As such, a film prepared according to Inventive Process 9 may be more easily deformed into a mold compared to a film prepared according to Inventive Process 10. Thus, the film prepared by Inventive Process 9 may be more easily deformed into moulds with greater complexity. Such films are, therefore, more favourably used to form complex articles, such as multiple compartment ADW pouches.

[0226] This suggests that, while films prepared by both Processes may be used, a film prepared by Inventive Process 9 is more favourable for a complex pouch design, for example a multicompartment pouch, such as a multicompartment ADW pouch.

[0227] The examples above show that Inventive Process 1-10, which are example of the invention, result in PVOH films with favourable thermoformability properties, such that the films may readily be used to prepare thermoformed packages (or pouches), in particular, thermoformed packages comprising multiple compartments.

[0228] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

PAT 15669- WO-PCT28CLAIMS1. A cast extrusion process for preparing a polyvinyl alcohol (PVOH) film, the process comprising the steps of: a. extruding a composition comprising at least one PVOH resin onto a first heat transfer roller; and b. feeding the composition from the first heat transfer roller onto a second heat transfer roller; wherein the first heat transfer roller has a temperature of from 20°C to 90°C, and the second heat transfer roller has a temperature which is less than the temperature of the first heat transfer roller.

2. A process according to claim 1, wherein the first heat transfer roller has a temperature of from 30°C to 90°C, preferably from 30°C to 50°C or from 50°C to 70°C.

3. A process according to any preceding claim, wherein the second heat transfer roller has a temperature of from 20°C to 50°C, preferably from 20°C to 40°C.

4. A process according to any preceding claim, wherein the at least one PVOH resin comprises a first PVOH resin.

5. A process according to claim 4, wherein the first PVOH resin has a degree of hydrolysis of from 87.0 to 89.0 mol.%.

6. A process according to claim 4 or 5, wherein the first PVOH resin has a weight average molecular weight of from about 50,000 g / mol to about 150,000 g / mol, preferably from about 70,000 g / mol to about 120,000 g / mol, and more preferably from about 80,000 g / mol to about 100,000 g / mol.

7. A process according to any of claims 4 to 6, wherein the first PVOH resin has a viscosity ranging from 5 to 30 mPa s of 4 wt.% aqueous solution at 20°C, preferably a viscosity ranging from 7 to 24 mPa s of 4 wt.% aqueous solution at 20°C, and more preferably a viscosity ranging from 9 to 18 mPa s of 4 wt.% aqueous solution at 20°C.PAT 15669- WO-PCT298. A process according to any of claims 4 to 7, wherein the at least one PVOH resin comprises a second PVOH resin.

9. A process according to claim 8, wherein the second PVOH resin has a weight average molecular weight of from about 10,000 g / mol to about 50,000 g / mol, preferably from about 20,000 g / mol to about 50,000 g / mol, and more preferably from about 35,000 g / mol to about 50,000 g / mol.

10. A process according to claim 8 or 9, wherein the second PVOH resin has a viscosity ranging from 1 to 7 mPa s of 4 wt.% aqueous solution at 20°C, more preferably a viscosity ranging from 2.5 to 7 mPa s of 4 wt.% aqueous solution at 20°C, and most preferably a viscosity ranging from 3.5 to 6.5 mPa s of 4 wt.% aqueous solution at 20°C.

11. A process according to any preceding claim, wherein the process further comprises, before step (a), adding the composition comprising the at least one PVOH resin into an extruder.

12. A process according to any preceding claim, wherein the process further comprises, before step (a), adding a plasticiser and / or a processing aid into the extruder; wherein preferably the processing aid is present in the composition an amount of from 0.5 to 5 wt.%; and wherein the plasticiser, which is preferably glycerine, is present in the composition preferably in an amount of from 15 to 35 wt.%.

13. A process according to any preceding claim, wherein the total amount of PV OH resin in the composition is from 70 to 80 wt.%.

14. A process according to any of claims 4 to 13, wherein the first PVOH resin is present in the composition in an amount of from 50 - 90 wt.%, from 50 - 80 wt.%, or from 50 - 65 wt.%; and wherein the second PVOH resin, if present in the composition, is present in an amount of from 10 - 40 wt.%, from 15 - 35 wt.%, or from 15 - 25 wt.%.

15. A process according to any preceding claim, wherein the process further comprises, after step (b):PAT 15669- WO-PCT30 c. forming a film; preferably wherein the film has a thickness of greater than 50pm, more preferably wherein the film has a thickness of from 50 - 200pm, 50 - 150pm, 50 - 120pm, or from 50 - 60pm; preferably to a thickness of from 80 - 100pm; comprising the composition comprising the at least one PV OH resin.

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