A process for the preparation of water-soluble films

Abstract

The invention is related to a cast extrusion process for preparing a water-soluble film, the process comprising the steps of: d) extruding a composition comprising at least one polyvinyl alcohol (PVOH) resin through a die, preferably a flat die; and e) contacting the composition with a cooling surface; the composition having a first velocity upon egress of the composition from the die and a second velocity upon contact with the cooling surface, wherein the percentage increase in velocity from the first velocity to the second velocity is at least 100%.

Description

[0001] PAT15645-WO-PCT

[0002] 1

[0003] A PROCESS FOR THE PREPARATION OF WATER-SOLUBLE FILMS

[0004] Technical Field of the Invention

[0005] The present invention relates to a process for manufacturing water soluble films. More particularly, the present invention relates to a process for manufacturing PVOH films having asymmetric stretch properties and / or improved shrink properties. The present invention further relates to water soluble films produced by the process and water-soluble packages comprising water soluble films produced by the present process.

[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 PAT15645-WO-PCT

[0010] 2 floorspace to the equipment used for the aqueous casting process, therefore, limiting the operations of the facility to carry out additional work.

[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] Additionally, for side-by-side arranged, multi-compartment pouches manufactured via thermoforming of thin films, such as ADW pouches, there is a difficulty to achieve the level of fill volume required for the desired cleaning performance when splitting in the product into multiple compartments, such as more than three compartments.

[0013] Known films produced by the above cast solution and blown extrusion processes have a similar stretching and shrinking behaviour in both directions, the so- called machine and transversal direction. As a result, the shape of the cavity to be formed is mostly equivalent to the resulting compartment of the pouch.

[0014] However, there are areas on the formed pouch which undergo greater stretching, usually around the bottom of the pouch.

[0015] In contrast, a film with asymmetric behaviour may exhibit a different stretch and shrink in the two directions.

[0016] This may allow the pouch dimensions to be reduced without losing volume, or the fill level can be increased by a larger cavity footprint while keeping the pouch dimensions constant.

[0017] For individuality packed detergents portions, such as Automatic dishwashing or laundry pouches there is a need to separate ingredients from each other due to incompatibility, or to be able to combine different textures such as powders, liquids, gets. Compact Pouches in a side-by-side arrangement are available on the market, usually combining up to 3 compartments. There are arrangements of up to 4 side by PAT15645-WO-PCT

[0018] 3 side compartments available in the laundry sector, but with the draw back of a very large and flat pouch and a high consumption of the water-soluble film.

[0019] As such, there is a need for additional compartments in side-by-side arrangement to be able to add further functions or textures while keeping the dimensions (specifically width and length) of the pouch small and compact. However, every additional compartment limits the available fill volume and therefore the level of active ingredients significantly.

[0020] This is a limiting factor not only for Automatic dishwashing detergents where the pouch needs to fit easily into the machine's dosage chambers, but also for applications where the size is limited to avoid excess film consumption and to meet the consumers need for multi-compartment but compact products.

[0021] 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, compared to processes of the prior art.

[0022] It is furthermore an aim of embodiments of the invention, to provide an improved water-soluble package comprising a water-soluble film.

[0023] It is also an aim of embodiments of the present invention to provide an improved process for manufacturing a water-soluble film having one or more asymmetric stretch and / or shrink properties.

[0024] It is also an aim of embodiments of the present invention to provide an improved process for manufacturing a water-soluble film having improved shrink properties.

[0025] It is further an aim of embodiments of the present invention to provide a water- soluble film and / or water-soluble package having one or more asymmetric stretch and / or shrink properties, and / or improved shrink properties. PAT15645-WO-PCT

[0026] 4 of the Invention

[0027] According to a first aspect of the present invention, there is provided a cast extrusion process for preparing a water-soluble film, the process comprising the steps of: a) extruding a composition comprising at least one PVOH resin through a die; preferably a flat die, and b) contacting the composition with a cooling surface, preferably a roller such as a chill roll; the composition having a first velocity upon egress of the composition from the die and a second velocity upon contact with the cooling surface, wherein the percentage increase in velocity from the first velocity to the second velocity is at least 100%.

[0028] The respective velocity calculations have been executed following the following equations:

[0029] Flat Die gap Fiiml * initial melt velocity flat die —

[0030] Melt velocity chill roll [m / s] = - - — - - —

[0031] Melt velocity increase flat die to chill roll [m / s] =

[0032] Percentaged melt velocity increase [%] = 100 [%] *

[0033] Surprisingly, the inventors observed that a cast extrusion process according to the present invention wherein there is at least a 100% velocity increase from the egress of the composition from the die to the contact of the composition with the cooling surface results in a water-soluble film having one or more asymmetric stretch and / or shrink properties, together with improved shrink properties.

[0034] Without being bound by theory, the inventors found that an increase in velocity between the egress of the composition from the die until contact with the cooling surface imparts a greater stretch in the machine direction during the extrusion process. This results in greater orientation of the film in the machine direction as it is extruded PAT15645-WO-PCT

[0035] 5 from the die. This greater orientation then results in an asymmetric shrink and stretch properties in one direction.

[0036] Beneficially, water soluble films prepared by the present process surprisingly have overall higher shrinking in length and / or width than existing films produced from solution cast and blown extrusion processes, wherein an asymmetric shrink and stretch behaviour has to be present. Additionally, the films produced by the process of the present invention also exhibit an improved stretch behaviour, specifically in the most critical areas, such as the bottom of the pouch, without compromising the thickness of the films. This allows for the production of water-soluble packages having a larger individual cavity size and multiple compartments, while still achieving the same final pouch dimensions.

[0037] 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 properties which are not found in PVOH films produced by known cast extrusion processes.

[0038] Further advantageously, the enhanced properties of the film means that the film can be readily used to create smaller dimensioned monodose articles, such as ADW pouches, and complex articles such as complex pouch designs which comprise multiple compartments, without compromising the fill volume.

[0039] 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.

[0040] 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- soluble package’ is used herein to refer to a package which at least partially disperses, PAT15645-WO-PCT

[0041] 6 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.

[0042] In one embodiment, the percentage increase in velocity is from 150 - 5000%, preferably from 250 - 3000%, and more preferably from 400 - 1500%.

[0043] Beneficially, the inventors found that an increase in velocity in the most preferred range of from 400 - 1500% resulted in a water-soluble film having the most improved shrink and stretch properties for providing the inventive asymmetric effect for the final film.

[0044] In one embodiment, the composition has a first velocity of from 0.005 - 0.20m / s, preferably from 0.01 - O.lOm / s, and more preferably from 0.02 - 0.08m / s.

[0045] In one embodiment, the composition has a second velocity of from 0.005 - 2m / s, preferably from 0.1 - 1.4m / s, and more preferably from 0.15 - 0.9m / s.

[0046] The first velocity may be approximated by the reciprocal of the thickness of the composition at the die exit, which is approximate to the die gap.

[0047] The second velocity may be approximated by the reciprocal of the final film thickness.

[0048] 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.

[0049] The cooling surface may be a surface having a temperature below the temperature of the composition during extrusion.

[0050] In one embodiment, the cooling surface may be cooled to a predetermined temperature.

[0051] The cooling surface may have a temperature of from at least 22°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or at least 90°C.

[0052] The cooling surface may have a temperature of no more than 22°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or no more than 90°C.

[0053] In one embodiment of the invention, the cooling surface may be a roller, preferably a chill roll. PAT15645-WO-PCT

[0054] 7

[0055] Preferably, the cooling surface is a rotatable roller, typically a chrome plated or stainless-steel roller onto which the melt is extruded in the preparation of a water- soluble film.

[0056] Rollers for use in extrusion processes 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, so as to provide enhanced temperature control and heat distribution across the roller.

[0057] The process may comprise at least two, three, four, five, six, seven, eight, nine or at least ten cooling surfaces.

[0058] In one embodiment, the roller may comprise at least two, three, four, five, six, seven, eight, nine or at least ten rollers.

[0059] In one embodiment, the invention may comprise a plurality of cooling surfaces.

[0060] Preferably, the invention may comprise a plurality of rollers.

[0061] In such an embodiment, the melt may pass sequentially through each roller.

[0062] Each cooling surface may have the same or different temperature.

[0063] The process may further comprise, after step (b), the following step:

[0064] (c) forming a water-soluble film from the composition.

[0065] In one embodiment, the step c) of forming the water-soluble film may comprise casting the water-soluble film.

[0066] 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.

[0067] 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. PAT15645-WO-PCT

[0068] 8

[0069] In one embodiment, the composition may be a melt.

[0070] In such an embodiment, step a) may comprise extruding a melt which is subsequently processed in step c) to form the film. In such embodiments, step a) may comprise forming a plurality of pellets or granules of the water-soluble mass, and step c) may comprise forming the pellets or granules into a film.

[0071] The pellets or granules may be formed by extruding the water-soluble melt, in the form of at least one rope, through a die plate comprising at least one die gap and cutting the or each rope into pellets or granules using a cutting blade or blades, which may be a rotating cutting blade or blades.

[0072] The pellets or granules may be passed through a second extruder, which may be a single or twin-screw extruder for example, to form a film.

[0073] The PVOH resin may have a degree of hydrolysis of from 87.0 mol.% to 89.0 mol.%, from 87.2 mol.% to 88.8 mol.%, from 87.4 mol.% to 88.6 mol.%, from 87.6 mol.% to 88.4 mol.%, from 87.8 mol.% to 88.2 mol.%, from 87.8 mol.% to 88.0 mol.%.

[0074] All weight average molecular weights described herein are determined by gel permeation chromatography.

[0075] The PVOH may have a weight average molecular weight of at least 35,000 g / mol., 50,000 g / mol., 60,000 g / mol., or at least 100,000 g / mol...

[0076] The PVOH resin may have a weight average molecular weight of from about 35,000 g / mol to about 150,000 g / mol, preferably from about 50,000 g / mol to about 120,000 g / mol, and more preferably from about 60,000 g / mol to about 90,000 g / mol.

[0077] Beneficially, in embodiments comprising a PVOH resin having a weight average molecular weight of at least 50,000 g / mol, in particular, 50,000 g / mol to 150,000 g / mol, ensures a suitable mechanical stability during the thermoforming and sealing process

[0078] Advantageously, in embodiments comprising a PVOH resin having a weight average molecular weight of no more than 50,000 g / mol, for example from 35,000 g / mol to 50,000 g / mol, the resin enables a reduction in the melt viscosity and provides even more favourable elastic properties, in addition to a further increased robustness suitable for the thermal sealing process. PAT15645-WO-PCT

[0079] 9

[0080] All weight average molecular weights described herein are determined by gel permeation chromatography.

[0081] In one embodiment, the composition may comprise a first PVOH resin.

[0082] The first PVOH resin may have a degree of hydrolysis of from 87.0 mol.% to 89.0 mol.%, from 87.2 mol.% to 88.8 mol.%, from 87.4 mol.% to 88.6 mol.%, from 87.6 mol.% to 88.4 mol.%, from 87.8 mol.% to 88.2 mol.%, from 87.8 mol.% to 88.0 mol.%.

[0083] 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 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.

[0084] 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.

[0085] 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 thermoforming and sealing process. In one embodiment, the composition may comprise a second PVOH resin.

[0086] The second PVOH resin may have a degree of hydrolysis of from 87.0 mol.% to 89.0 mol.%, from 87.2 mol.% to 88.8 mol.%, from 87.4 mol.% to 88.6 mol.%, from 87.6 mol.% to 88.4 mol.%, from 87.8 mol.% to 88.2 mol.%, from 87.8 mol.% to 88.0 mol.%.

[0087] The second PVOH resin may have a weight average molecular weight of at most about 50,000 g / mol.

[0088] 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. PAT15645-WO-PCT

[0089] 10

[0090] 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 viscosity and provides even more favourable elastic properties, in addition to a further increased robustness suitable for the thermal sealing process.

[0091] 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. .

[0092] The process may further comprise, before step (a), a step of adding the composition into an extruder.

[0093] The extruder may be, for example, a single or twin-screw extruder.

[0094] The composition may comprise at least one plasticiser.

[0095] 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 20-25°C.

[0096] 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 20-25°C.

[0097] Beneficially, the use of a liquid plasticiser improves the forming properties and sealing strength of the resulting films.

[0098] 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.%.

[0099] Advantageously, the presence of a plasticiser in the above amounts allows the film to have sufficient elasticity such that the process of the present invention is able to impart the improved shrink and / or stretch properties onto the resulting film.

[0100] 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. PAT15645-WO-PCT

[0101] 11

[0102] 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.

[0103] Examples of esters of carboxylic acids include but are not limited to esters of citric acid, malic acid, maleic acid or succinic acid.

[0104] The composition may comprise more than one plasticiser, for example the composition may comprise a blend of plasticisers.

[0105] 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.

[0106] 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.

[0107] The plasticiser may be a plasticiser which is solid at room or ambient temperature.

[0108] 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 20-25 °C.

[0109] The composition may comprise at least one processing aid.

[0110] 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.

[0111] The at least one processing aid may be present in the composition in an amount of from 0.5 wt.% to 5.0 wt.%.

[0112] The composition may comprise more than one processing aid, for example the composition may comprise a blend of processing aids. PAT15645-WO-PCT

[0113] 12

[0114] 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 180°C to 210°C to melt the components of the composition into a liquid composition. The melt temperature may be from 185°C to 205°C, from 190°C to 205°C, from 190°C to 200°C, or 195°C.

[0115] The total amount of PVOH resin in the composition may be from 50 - 90 wt.%.

[0116] 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.%.

[0117] 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.%.

[0118] Advantageously, water soluble films prepared by a process of the first aspect of the invention surprisingly have overall higher shrinking in length and / or width than existing films produced from solution cast and blown extrusion processes; wherein in the context of the present invention an asymmetric shrink and stretch behaviour has to be present. Herein, the films produced by the process of the present invention also exhibit an improved stretch behaviour in the most critical areas, such as the bottom of the pouch, without compromising the thickness of the films. This allows for the production of water-soluble packages having a larger individual cavity size and multiple compartments, while still achieving the same final pouch dimensions.

[0119] In one embodiment, the length of the water-soluble film may shrink after thermoforming by at least 1 %, 5 %, 10 %, 15 %, or 20 %.

[0120] In one embodiment, the length of the water-soluble film may shrink after thermoforming by 1 - 20 %, 5 - 17 %, or from 10 - 15 %.

[0121] In one embodiment, the width of the water-soluble film may shrink after thermoforming by at least 3 %, 5 %, or at least 6 %.

[0122] The width of the water-soluble film may shrink after thermoforming by 1 - 7 %, 3 - 7 %, or from 5 - 6 %. PAT15645-WO-PCT

[0123] 13

[0124] The length of the water-soluble film means in the context of the present invention the machine direction while the width of the water-soluble film means the transverse direction.

[0125] In one embodiment, the film may have one or more asymmetric properties.

[0126] The asymmetric properties may be a stretch and / or shrink property of the film.

[0127] In one embodiment, the film may have a greater stretch in a direction along its width in comparison to a stretch in a direction along its length.

[0128] Alternatively, the film may have a greater stretch in a direction along its length in comparison to a stretch in a direction along its width.

[0129] In one embodiment, the film may have a greater percentage shrink of its width after thermoforming in comparison to the percentage shrink of its length after thermoforming.

[0130] Alternatively, the film may have a greater percentage shrink of its length after thermoforming in comparison to the percentage shrink of its width after thermoforming.

[0131] 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.

[0132] The invention according to the second aspect may optionally include any of the features of the invention according to any other aspect.

[0133] 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.

[0134] 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 PAT15645-WO-PCT

[0135] 14 plurality of stages of a dishwashing cycle or over at least one stage of a plurality of dishwashing cycles.

[0136] 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, 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 three, four or five pockets.

[0137] The package may be in a unit-dose format.

[0138] 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 quantity required for a single wash cycle of a machine dishwasher. In some embodiments the unit dose format also includes a liquid detergent composition.

[0139] The package may be in the form of a unit-dose format for a single use.

[0140] 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.

[0141] 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.

[0142] 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. PAT15645-WO-PCT

[0143] 15

[0144] The invention according to the first aspect may optionally include any of the features of the invention according to any other aspect.

[0145] Detailed Description of the Invention

[0146] 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:

[0147] Figure 1 shows a three-compartment package formed using a PVOH film prepared according to an embodiment of the invention (left) compared with a multiple compartment package formed using a standard commercial PVOH film Aicello Solublon GS (right).

[0148] Figure 2 shows a five-compartment package formed using a PV OH film prepared according to an embodiment of the invention (left) compared with a multiple compartment package formed using a standard commercial PVOH film Aicello Solublon GS (right).

[0149] Figure 3 shows a four-compartment package formed using a PV OH film prepared according to an embodiment of the invention (bottom) compared with a multiple compartment package formed using a standard commercial PVOH film Aicello Solublon GS (top).

[0150] Figure 4 shows a three-compartment package filled with a solid, liquid and gel fill material formed using a PVOH film prepared according to an embodiment of the invention (bottom) compared with a multiple compartment package formed using a standard commercial PVOH film Ecopol Hydrolene LTF-TB (top).

[0151] Figure 5 shows cavities used to form water soluble pouches in order to measure the maximum local stretch of a PVOH film in the highlighted area.

[0152] Figure 6 shows load displacement graphs measured in the machine direction (MD) and transverse direction (TD) for films produced according to the present invention, composition 1 (top left), composition 2 (top right), PAT15645-WO-PCT

[0153] 16 composition 3 (middle left) and composition 4 (middle right), and standard commercial films Ecopol Hydrolene LTF-TB (bottom left) and Aicello Solublon GS (bottom right).

[0154] Examples

[0155] Composition 1

[0156] A water-soluble film was prepared according to the present invention comprising a composition, Composition (1), prepared according to the following:

[0157] Composition (1):

[0158] Composition (1) comprised PVOH resin (1) and PVOH resin (2). PVOH resin (2) having a degree of hydrolysis of 87-89 mol.%, a viscosity of 4-6 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 39900 g / mol. PVOH resin (1) having a degree of hydrolysis of 86-90 mol.%, a viscosity of 15-19 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 100000 g / mol.

[0159] A PVOH film was prepared using Composition (1) and according to the following inventive process of the invention.

[0160] All solid parts of Composition (1), namely the two PVOH resins and processing aids, were added to a hopper and subsequently led to an extruder as a plurality of granules. The extruder was a Collin ZK 25*42D twin-screw extruder (diameter: 25mm, [L / D] = 42, length = 1050mm, Screw speed 300-600 rpm). After the plurality of granules have PAT15645-WO-PCT

[0161] 17 been mixed and further crushed in a first zone of the extruder, all liquid parts of Composition (1), namely glycerine, were subsequently added to a subsequently arranged second zone of the extruder in which all solid and liquid parts of Composition (1) were mixed and finally heated to a melt temperature of from 190°C to 205°C to melt all the components of the composition into a liquid composition. The liquid composition was then fed to a flat die. The flat die had a width of 400mm and a die gap of approximately 800pm, through which the liquid composition was extruded at a first velocity of from 0.005 m / s. The liquid composition was then extruded onto a first cooling surface comprising a chrome-plated rotating roller, and is formed as a cast film upon the first roller. The composition had a second velocity upon contacting the cooling surface of approximately 0.047 m / s and the percentage increase in velocity from the first velocity to the second velocity was approximately 789%. The cast film was then transferred to a number of subsequent rollers and cast to a thickness of 90pm by a trimmer before being collected as a wound film upon a winding system.

[0162] Advantageously, the film of composition 1 was observed to have improved shrink and stretch properties according to the invention, wherein the inventive asymmetric effect for the final film has been shown as described in the below assessments.

[0163] A water-soluble film was prepared according to the present invention comprising a composition, Composition (2), prepared according to the following:

[0164] Composition (2) comprised PVOH resin (1) and PVOH resin (2). PVOH resin (2) having a degree of hydrolysis of 87-89 mol.%, a viscosity of 4-6 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 39900 g / mol. PVOH resin (1) having a degree of hydrolysis of 86-90 mol.%, a viscosity of 15-19 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 100000 g / mol. PAT15645-WO-PCT

[0165] 18

[0166] A PVOH film was prepared using Composition (2) and according to the following inventive process of the invention.

[0167] All solid parts of Composition (2), namely the two PVOH resins and processing aids, were added to a hopper and subsequently led to an extruder as a plurality of granules. The extruder was a Collin ZK 25*42D twin-screw extruder (diameter: 25mm, length [L / D]: 42 =1050mm, velocity: 300-600 rpm). After the plurality of granules have been mixed and further crushed in a first zone of the, all liquid parts of Composition (2), namely glycerine, polyethylene glycol 200 and 1,2 propylene glycol, were subsequently added to a subsequently arranged second zone of the extruder in which all solid and liquid parts of Composition (2) were mixed and finally heated to a melt temperature of from 190°C to 205°C to melt all the components of the composition into a liquid composition. The liquid composition was then fed to a flat die. The flat die had a width of 400mm and a die gap of approximately 800pm, through which the liquid composition was extruded at a first velocity of from 0.0078 m / s. The liquid composition was then extruded onto a first cooling surface comprising a chrome-plated rotating roller, and is formed as a cast film upon the first roller. The composition had a second velocity upon contacting the cooling surface of approximately 0.06 m / s and the percentage increase in velocity from the first velocity to the second velocity was approximately 680%. The cast film was then transferred to a number of subsequent rollers and cast to a thickness PAT15645-WO-PCT

[0168] 19 of 90pm by a trimmer before being collected as a wound film upon a winding system.

[0169] Advantageously, the film of composition 2 was observed to have improved shrink and stretch properties according to the invention, wherein the inventive asymmetric effect for the final film has been shown as described in the below assessments.

[0170] Composition 3

[0171] A water-soluble film was prepared according to the present invention comprising a composition, Composition (3), prepared according to the following:

[0172] Composition (3):

[0173] Composition (3) comprised PVOH resin (1) and PVOH resin (2). PVOH resin (2) having a degree of hydrolysis of 87-89 mol.%, a viscosity of 4-6 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 39900 g / mol. PVOH resin (1) having a degree of hydrolysis of 86-90 mol.%, a viscosity of 15-19 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 100000 g / mol.

[0174] A PVOH film was prepared using Composition (3) and according to the following inventive process of the invention.

[0175] All solid parts of Composition (3), namely the two PVOH resins and processing aids, were added to a hopper and subsequently led to an extruder as a plurality of PAT15645-WO-PCT

[0176] 20 granules. The extruder was a 60*32D Twin-screw extruder (diameter 60mm, [L / D]: 32, length = 1920mm, velocity 250-350rpm. After the plurality of granules have been mixed and further crushed in a first zone of the extruder, all liquid parts of Composition (3) were subsequently added to a subsequently arranged second zone of the extruder in which solid and liquid parts of Composition (3), namely glycerine, were mixed and finally heated to a melt temperature of from 190°C to 205°C to melt all the components of the composition into a liquid composition. The liquid composition was then fed to a flat die. The flat die had a width of 1200mm and a die gap of approximately 1200pm, through which the liquid composition was extruded at a first velocity of from 0.025 m / s. The liquid composition was then extruded onto a first cooling surface comprising a chrome-plated rotating roller, and is formed as a cast film upon the first roller. The composition had a second velocity upon contacting the cooling surface of approximately 0.336 m / s and the percentage increase in velocity from the first velocity to the second velocity was approximately 1233%. The cast film was then transferred to a number of subsequent rollers and cast to a thickness of 90pm by a trimmer before being collected as a wound film upon a winding system.

[0177] Advantageously, the film of composition 3 was observed to have improved shrink and stretch properties according to the invention, wherein the inventive asymmetric effect for the final film has been shown as described in the below assessments.

[0178] Composition 4

[0179] A water-soluble film was prepared according to the present invention comprising a composition, Composition (4), prepared according to the following:

[0180] Composition (4):

[0181] Composition (4) comprised PVOH resin (1) and PVOH resin (2). PVOH resin (2) having a degree of hydrolysis of 87-89 mol.%, a viscosity of 4-6 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 39900 g / mol. PVOH resin (1) having a degree of hydrolysis of 86-90 mol.%, a viscosity of 15-19 mPa s of 4 wt.% aqueous solution at 20°C, and a weight average molecular weight of 100000 g / mol. PAT15645-WO-PCT

[0182] 21

[0183] A PVOH film was prepared using Composition (4) and according to the following inventive process of the invention.

[0184] All solid parts of Composition (4), namely the two PVOH resins, Sorbitol and processing aids, were added to a hopper and subsequently led to an extruder as a plurality of granules. The extruder was a 60*32D Twin-screw extruder (diameter 60mm, [L / D]: 32, length = 1920mm, velocity 250-350rpm. After the plurality of granules have been mixed and further crushed in a first zone of the extruder, all liquid parts of Composition (4), namely glycerine, were subsequently added to a subsequently arranged second zone of the extruder in which all solid and liquid parts of Composition (4) were mixed and finally heated to a melt temperature of from 190°C to 205°C to melt all the components of the composition into a liquid composition. The liquid composition was then fed to a flat die. The flat die had a width of 1200mm and a die gap of approximately 1200 pm, through which the liquid composition was extruded at a first velocity of from 0.025 m / s. The liquid composition was then extruded onto a first cooling surface comprising a chrome-plated rotating roller, and is formed as a cast film upon the first roller. The composition had a second velocity upon contacting the cooling surface of approximately 0.336 m / s and the percentage increase in velocity from the first velocity to the second velocity was approximately 1233%. The cast film was then transferred to a number of subsequent rollers and cast to a thickness of 90pm by a trimmer before being collected as a wound film upon a winding system. PAT15645-WO-PCT

[0185] 22

[0186] Advantageously, the film of composition 4 was observed to have improved shrink and stretch properties according to the invention, wherein the inventive asymmetric effect for the final film has been shown as described in the below assessments.

[0187] Shrink Assessment

[0188] In order to assess the shrink properties of the films prepared by the process of the present invention, a multicompartment ADW package was formed using a PVOH film prepared according to composition 1 and composition 2 according to the following process.

[0189] Films prepared according to composition 1 and composition 2 were used to make a thermoformed pouch by applying a first film to a thermoforming cavity, and applying heat (about 130°C) and a vacuum (about 490 mbar).

[0190] A liquid or solid fill material was then filled into the cavity and a second film having the same composition as the first film was placed upon the first thermoformed PVOH film such that the second PVOH film overlies the first thermoformed film and the second film was wetted using a wet roller and pressed onto the cavity to seal the pouch.

[0191] The dimensions (length and width) were measured after the pouches were released from the cavities and the dimensions were compared with the dimensions of the cavity.

[0192] The shrink assessment was repeated for each film composition and an average of the dimensions was recorded.

[0193] The above assessment was also carried out on commercially available films, Ecopol Hydrolene LTF-TB (sourced from Ecopol S.p.A., Italy) and Aicello Solublon GS (sourced from AICELLO CORPORATION, Japan), wherein the film of Ecopol was produced by blown extrusion while the film of Aicello was produced by cast solution.

[0194] The percentage shrink of the thermoformed pouches when filled with a liquid fill material are shown below in Table 1. PAT15645-WO-PCT

[0195] 23

[0196] Table 1: Average thermoformed pouch shrink percentage of films after release from a single cavity when filled with a liquid fill material.

[0197] The percentage shrink of the thermoformed pouches when filled with a powder solid fill material are shown below in Table 2. Table 2: Average thermoformed pouch shrink percentage of films after release from a single compartment cavity when filled with a solid fill material.

[0198] As seen in the table, a pouch made by a film produced according to a process of the present invention has a greater shrink of 18% with a liquid fill material when compared with two commercial films Aicello Solublon GS and Ecopol Hydrolene LTF- TB (15.2 and 10.1% respectively). PAT15645-WO-PCT

[0199] 24

[0200] Less shrink overall was observed with a solid powder fill material due to the lower compressibility of the material. However, the films prepared by a process of the present invention still shrunk to a larger extent compared to commercial films.

[0201] The shrink assessments were also carried out on multicompartment cavities. Tables 3, 4 and 5 below show the percentage shrink after thermoforming and release from cavities having four, three and five compartments respectively.

[0202] Table 3: Average thermoformed pouch shrink percentage of films after release from a four -compartment cavity when filled with a liquid fill material.

[0203] Table 4: Average thermoformed pouch shrink percentage of films after release from a three-compartment cavity when filled with a liquid fill material.

[0204] Table 5: Average thermoformed pouch shrink percentage of films after release from a five-compartment cavity when filled with a liquid fill material. PAT15645-WO-PCT

[0205] 25

[0206] As shown in the above tables and Figures 1-3, films prepared by a process of the present invention showed a higher total shrink when thermoforming for all multichamber cavities with the highest difference seen in the five-chamber cavity.

[0207] In a further shrink assessment, the shrink of a further two films produced via a process of the present invention, composition 2 and composition 3, were measured and compared with the commercial film Ecopol Hydrolene LTF-TB. The pouches were produced after thermoforming and release from cavities having three chambers and filled with a combination of powder, gel and liquid fill material.

[0208] Table 6: Average thermoformed pouch shrink percentage of films after release from a three-compartment cavity when filled with a powder, gel and liquid fill material.

[0209] As seen in table 6 and Figure 4, a film prepared according to the present invention has a higher overall shrink and is thus able to provide smaller pouch dimensions at the same fill volume for a variety of different fill materials. Additionally, it can be observed that the shrinking properties of the films prepared according to the present invention are asymmetric when compared with standard commercial films. This is beneficial in the production of asymmetrical pouches which consumers may find more appealing.

[0210] This higher shrink beneficially also provides higher fill volumes. For example, the inventors observed that using a film prepared by a process of the present invention allows for a larger cavity and therefore higher film volume when compared to a standard film such as Aciello GS film and Ecopol Hydrolene LTF-TB. PAT15645-WO-PCT

[0211] 26

[0212] Thickness and Asymmetric Stretch Assessment

[0213] Additionally, the inventors also observed that a film prepared by the process of the present invention has improved thickness in the areas wherein the most stretch is applied during thermoforming of water-soluble pouches when compared with the standard commercial films Aicello Solublon GS and Monosol M8630 (sourced from Monosol LLC, USA).

[0214] This is measured in the following assessment as maximum local stretch.

[0215] In order to determine the maximum local stretch a square grid was printed onto the films and the film was deep drawn into a cavity. The change in the dimensions and area of the squares of the grid at the most critical area and deepest point of the cavities were measured after forming. This deepest point is the point at which the film is expected to be the thinnest.

[0216] The resulting areas of the square at the deepest point after forming was then compared with the area before forming and a stretch ratio was calculated. Four different shaped deep draw cavities were used and the critical area is highlighted in Figure 5.

[0217] The result was expressed as a maximum local stetch shown in Table 7 below. PAT15645-WO-PCT

[0218] 27 PAT15645-WO-PCT

[0219] 28

[0220] Table 7: Maximum local stretch and remaining thickness in most critical areas of thermoformed pouches produced using Cavities A, B, C andD.

[0221] As shown in Table 7, pouches produced from films prepared according to the present invention show the lowest maximum stretch in a number of the shaped cavities, and therefore the film is less thinned out in the most critical areas of the pouch.

[0222] Surprisingly, this is thought to be achieved by the asymmetric properties of the films. For example, the cavity design forces the film to stretch differently in two directions as it is longer than wide.

[0223] An asymmetric stretch behaviour allows the film to stretch easier in one direction than the other, so the X and Y dimensions of the square grid in the most critical area differ less before forming and after forming.

[0224] The average x and y dimension and ratio of the average x dimensions and y dimensions of the square grid in the most critical area is shown below in Table 8. PAT15645-WO-PCT

[0225] 29

[0226] Table 8: Comparison of average x and y dimension ratios of thermoformed pouches produced using Cavities A, B, C andD.

[0227] As shown in Table 8, the best results are achieved by films prepared by the process of the present invention where the X / Y ratio is closest to 1. In contrast, the PAT15645-WO-PCT

[0228] 30 much more symmetric stretchable films Aicello Solublon GS and Monosol M8630 are overstretched in one direction, while the asymmetric films of the present invention can be stretched more homogenous. 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.

[0229] The asymmetric behaviour of films was investigated further by measuring the load displacement of films prepared according to composition 1, composition 2, composition 3, composition 4, Ecopol Hydrolene LTF-TB, and Aicello Solublon GS.

[0230] A tensile tester (Zwickiline available from Zwick Roett) was used according to DIN EN ISO 527 1-3 with the following parameters:

[0231] Displacement speed 100 mm / min;

[0232] - Pre load 0.2 N; initial gap 50 mm;

[0233] Sample width 15 mm;

[0234] The results of the load displacement test can be seen in Figure 6.

[0235] As shown in Figure 6, the films prepared according to the present invention demonstrate a larger difference in their stretching behaviour in the machine and transverse direction when compared with the commercially available films Ecopol Hydrolene LTF-TB, and Aicello Solublon GS.

[0236] For example, the films prepared according to the present invention require a higher resistance to stretch in the machine direction in comparison to the transverse direction. This results in a higher tensile strength in the machine direction, whereas the film shows a higher elongation at break when stretched in the transverse direction.

[0237] Beneficially, these asymmetric stretching properties allow the film to better form asymmetric pouches and provide better integrity of the pouches in the most critical areas due to the improved stretch. PAT15645-WO-PCT

[0238] 31

[0239] 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

PAT15645-WO-PCT32CLAIMS1. A cast extrusion process for preparing a water-soluble film, the process comprising the steps of: a) extruding a composition comprising at least one polyvinyl alcohol (PVOH) resin through a die, preferably a flat die; and b) contacting the composition with a cooling surface, preferably a roller such as a chill roll; the composition having a first velocity upon egress of the composition from the die and a second velocity upon contact with the cooling surface, wherein the percentage increase in velocity from the first velocity to the second velocity is at least 100%.

2. A process according to claim 1 wherein the percentage increase in velocity is from 150 - 5000%, preferably from 250 - 3000%, and more preferably from 400 - 1500%.

3. A process according to any preceding claim, wherein the composition has a first velocity of from 0.005 - 0.20m / s, preferably from 0.01 - O.lOm / s, and more preferably from 0.02 - 0.08m / s.

4. A process according to any preceding claim wherein the composition has a second velocity of from 0.005 - 2m / s, preferably from 0.1 - 1.4m / s, and more preferably from 0.15 - 0.9m / s.

5. A process according to any preceding claim, wherein 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.

6. A process according to any preceding claim, wherein the PVOH resin has a weight average molecular weight of at least 35,000 g / mol; preferably wherein the PVOH resin has a weight average molecular weight of from 35,000 g / mol to 150,000 g / mol, more preferably from about 50,000 g / mol to about 120,000 g / mol, and most preferably from about 60,000 g / mol to about 90,000 g / mol.PAT15645-WO-PCT337. A process according to any preceding claim, wherein the composition comprises a plasticiser in an amount of from 15 to 35 wt.% by weight of the composition.

8. A process according to any preceding claim, wherein the total amount of PV OH resin in the composition is from 50 - 90 wt.% by weight of the composition.

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

10. A process according to claim 9, 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.

11. A process according to claim 9 or 10, 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.

12. A process according to any one of claims 9 to 11, wherein the first PVOH resin is present in an amount of from 50 -90 wt.% and the second PVOH resin is present in an amount of from 10 - 40 wt.% by weight of the composition.

13. A process according to any preceding claim, wherein the process further comprises, after step (b): c) forming a film comprising the composition comprising the at least one PVOH resin.

14. A process according to claim 13, 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.

15. A thermoformed package for an automatic dishwashing cycle, wherein the thermoformed package comprises at least one PVOH film prepared according to the process of any of claims 1 to 14.

Images