thermoforming

Abstract

The invention is related to a method of thermoforming a water-soluble polymer film, the method comprising the steps of: a. Providing a water-soluble polymer film having a thickness of at least 100 microns; b. Contacting the water-soluble polymer film with water to provide a wetted water-soluble polymer film; c. Thermoforming the wetted water-soluble polymer film. The invention is further related to a method of manufacturing a water-soluble unit dose article, said article comprising at least one composition packaged in a container comprising a water-soluble polymer film, the method comprising steps: a. Providing a water-soluble polymer film having a thickness of at least 100 microns; b. Contacting the water-soluble polymer film with water to provide a wetted water-soluble polymer film; c. Thermoforming the wetted water-soluble polymer film to produce a thermoformed open water-soluble polymer film container, said container defining at least one internal compartment and comprising at least one opening to the at least one compartment; d. At least partially filling the at least one internal compartment of the thermoformed open water-soluble polymer film container with at least one composition; and e. Sealing the at least one opening of the open container to provide the water-soluble unit dose article.

Description

[0001] PAT 15705- WO-PCT

[0002] 1

[0003] THERMOFORMING

[0004] Technical Field of the Invention

[0005] The present invention relates to methods of thermoforming polymer films.

[0006] Background to the Invention

[0007] Water-soluble polymer films are commonly used as packaging materials to simplify dispersing, pouring, dissolving, and dosing of a material to be delivered. A consumer can, for example, directly add a composition packaged in a water-soluble polymer film to a mixing vessel, such as a bucket, sink, or washing machine. Advantageously, this provides for accurate dosing while eliminating the need for the consumer to measure the composition. Additionally, the water-soluble polymeric film packaging can separate otherwise strong chemistries from the consumer’s hand, protecting the consumer from contacting reactive chemicals. The packaged composition may also reduce mess that would be associated with dispensing a similar composition from a vessel, such as pouring a composition from a bottle. In summary, soluble pre-measured polymeric film packages provide for convenience and safety for the consumer in a variety of applications.

[0008] Packaging which can hold multiple compositions or ingredients also exists. However, in such packaging, there is often a need to separate individual compositions or ingredients from one another due to innate incompatibilities and to improve long-term stability.

[0009] A range of multi compartment containers are known, but typically only employ up to three compartments. A higher number of compartments in multicompartment containers made using water-soluble polymer films decreases the achievable volume of the compartments for each composition / ingredient and consequently requires a higher film consumption. For applications such as automatic dishwashing (ADW), there is also a PAT 15705- WO-PCT

[0010] 2 need to reduce the width and length dimensions of multicompartment containers to ensure a good fit into a dosage chamber and release in wash. As such, it can be difficult to achieve a balance between ensuring that the final size of the multicompartment container is small enough and suitable for application and ensuring enough of the contained compositions / ingredients can be contained in the container to provide the correct dosage level of the compositions / ingredients. This challenge is significantly exemplified as the number of compartments in the container are increased.

[0011] Stretching of water-soluble polymer films has been investigated in attempt to produce packaging containers which can contain greater amounts of compositions / ingredients without greatly increasing width and length of the final container.

[0012] Most current commercially available water-soluble polymer films are PVOH films and are typically available with thicknesses of up to 90 microns. The stretching properties of these films are, in today’s usage, already exhausted and such films cannot be significantly expanded without compromising the film’s robustness and stability.

[0013] Whilst thicker films should theoretically be able to be stretched to a greater extent than thinner films, in practice, thermoforming technology has limitations in terms of heat transfer and vacuum strength, leading to deficiencies in the forming process and producing thermoformed films with undesired forming properties. Furthermore, when thicker films are thermoformed, higher temperatures and vacuum conditions are typically required given the larger amount of material which must be heated to a softening temperature and a greater absolute force required to stretch and mould the thicker film. This naturally makes the process highly energy intensive. PAT 15705- WO-PCT

[0014] 3

[0015] There exists a need for improved methods of thermoforming thicker films that overcome or mitigate at least one problem of the prior art.

[0016] It is an aim of embodiments of the present invention to overcome or mitigate at least one problem of the prior art, whether expressly described herein or not.

[0017] Summary of the Invention

[0018] According to a first aspect of the invention, there is provided a method of thermoforming a water-soluble polymer film, the method comprising the steps of:

[0019] (a) Providing a water-soluble polymer film having a thickness of at least 100 microns;

[0020] (b) Contacting the water-soluble polymer film with water to provide a wetted water- soluble polymer film; and

[0021] (c) Thermoforming the wetted water-soluble polymer film.

[0022] Such a method has been found to allow for excellent thermoforming of thick water- soluble polymer films, which avoids undesired forming properties typically experienced when using methods of the prior art.

[0023] Furthermore, the method advantageously does not interfere with the film production process and produces no negative impacts on the manufacturing conditions used to form thermoformed products, such as containers, including on the feeding of films to a thermoforming line, sealing of thermoformed containers, and handling properties of final thermoformed products.

[0024] Water-soluble films are known to be hygroscopic, and application of water would be thought to render the film too sticky to process in a thermoforming method. In addition, PAT 15705- WO-PCT

[0025] 4 films contacted with water would be expected to be weak on thermoforming, and when used to form thermoformed containers, unable to securely contain compositions / ingredients. Surprisingly, however, contacting the water-soluble polymer film with water in the method of the invention confers additional elasticity / flexibility to the film without negatively impacting the film’s stability (dissolving the film) and mechanical properties (rendering the film too sticky or fragile to be processed, or too weak to hold in ingredients / compositions once thermoformed).

[0026] The wetted films can also advantageously be thermoformed using lower temperatures and less harsh vacuum conditions than methods of the prior art for thermoforming thick films, as the additional elasticity / flexibility conferred by contacting the films with water means that less heat is required to soften the films and less harsh vacuum conditions are required to mould the films in the thermoforming process.

[0027] Surprisingly, despite the additional elasticity / flexibility conferred by contacting films with water, thermoformed products of the method of the invention also demonstrate an enhanced shrinking effect, especially when thermoforming is performed at lower temperatures. The thermoformed products have a larger memory effect, which is particularly useful when producing thermoformed containers. The elasticity provided by contacting the films with water allows for greater stretching of the thermoformed containers, allowing greater amounts of compositions / ingredients to be inserted into the containers. The memory effect thereafter allows the thermoformed container to shrink in width and length after composition / ingredient has been added to provide the container with minimal dimensions whilst still securely containing the desired amount of composition / ingredient. PAT 15705- WO-PCT

[0028] 5

[0029] The term “water-soluble” as used herein may refer to a material which at least partially dissolves or disperses in water at 20 °C, preferably within 10 minutes.

[0030] The water-soluble polymer film preferably comprises at least one surface. Preferably, the water-soluble polymer film comprises two opposing surfaces. The film may be in the form of a sheet with the two opposing surfaces.

[0031] In some embodiments, the water-soluble polymer film comprises at least one water- soluble polymer.

[0032] In some embodiments, the water-soluble polymer film comprises at least one polymer that is independently selected from the group consisting of: a polyalcohol (preferably polyvinyl alcohol), a polysaccharide, a peptide or protein, and combinations thereof.

[0033] The water-soluble polymer film may comprise the at least one polymer in a total amount of at least 50 wt.% of the film, or of at least 55, 60, 65, 70, 75, 80, 85, 90, or of at least 95 wt.% of the film. In some embodiments, the film is made entirely of the at least one polymer.

[0034] The water-soluble polymer film may comprise the at least one polymer in a total amount of between 50-100 wt.%, or between 55-95, 60-90, 65-85, or between 70-80 wt.%.

[0035] In some embodiments, the water-soluble polymer film comprises at least one polysaccharide that is independently selected from the group consisting of: carrageenan; pectin; alginate; chitosan; cellulose; arabinoxylan; starch; amylopectin; maltodextrin; chitin; pullalan; xanthum; xanthan gum; dextran; welan; gellan; diutan; scleroglucan; levan; elsinan; alteman; soybean polysaccharide; a polysaccharide derived from soybean cotyledon, soybean meal or okara; furcellaran; and copolymers, salts, derivatives and combinations thereof. PAT 15705- WO-PCT

[0036] 6

[0037] In particularly preferred embodiments, the water-soluble polymer film comprises a poly alcohol, most preferably polyvinyl alcohol (PVOH) or a derivative or copolymer thereof.

[0038] The PVOH of the film may be partially or fully alcoholised or hydrolysed. The PVOH of the film may be an at least 10% alcoholised or hydrolysed polyvinyl acetate film, or an at least 20, 30, 40, 50, 60, 70, 80, 90, or an at least 95% alcoholised or hydrolysed polyvinyl acetate film. The PVOH of the film may be a no greater than 98% alcoholised or hydrolysed polyvinyl acetate film, or ano greater than 96, 94, 92, 90, 88, 86, 84, 82, or a no greater than 80% alcoholised or hydrolysed film. The PVOH of the film may be a polyvinyl acetate film that is from 40-100% alcoholised or hydrolysed, preferably from 70-92%, or from about 85-92% alcoholised or hydrolysed.

[0039] In some embodiments, the water-soluble polymer film comprises PVOH or a derivative thereof in a total amount of at least 50 wt.% of the film, or of at least 55, 60, 65, 70, 75, 80, 85, 90, or of at least 95 wt.% of the film. In some embodiments, the film is made entirely of PVOH or a derivative thereof.

[0040] In some embodiments, the water-soluble polymer film comprises PVOH or a derivative thereof in a total amount of no greater than 95 wt.% of the film, or no greater than 90, 85, or no greater than 80 wt.% of the film.

[0041] The water-soluble polymer film may comprise PVOH or a derivative thereof in a total amount of between 50-100 wt.%, or between 55-95, 60-90, 65-85, or between 70-80 wt.%.

[0042] In some embodiments, the water-soluble polymer film comprises at least one plasticiser. PAT 15705- WO-PCT

[0043] 7

[0044] The plasticizer may comprise but is not limited to one or more of the group consisting of: glycerol, diglycerin, sorbitol, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycols up to 400 Da molecular weight, hexylene glycol, neopentyl glycol, trimethylolpropane, polyether polyols, polyether diol, polyether triol, xylitol, 2-methyl- 1,3 -propanediol (MPDiol®), ethanolamines, glycerol propylene oxide polymers (such as, for example, Voranol™ available from The Dow Chemical Company), or combinations thereof. In some preferred embodiments, the plasticizer is or comprises glycerol.

[0045] The water-soluble polymer film may comprise the plasticizer in a total amount of at least 1 wt.% of the film, or at least 2, 3, 4, 5, or at least 10, or at least 15 wt.% of the film. The film may comprise the plasticizer in a total amount of no greater than 50 wt.% of the film, or no greater than 45, 40, 35, 30, or no greater than 25 wt.% of the film. The film may comprise the plasticizer in a total amount of between 1-50 wt.%, or between 5-45, 10-40, 15-35, or between 20-30 wt.% of the film.

[0046] In some embodiments, the water-soluble polymer film comprises one or more additional ingredients independently selected from the group consisting of: surfactants, colourants, antioxidants, acid scavengers, fillers, defoamers, and combinations thereof.

[0047] Said one or more additional ingredients independently may be present in an amount of between 0.25 wt%-5 wt%, or between 0.5 wt%-2.5 wt%, or between 1 wt%-2 wt%.

[0048] In some embodiments, the water-soluble polymer film has a thickness of at least 110 microns, or at least 150, or at least 200 microns. The water-soluble polymer film may have a thickness of no greater than 700 microns, or no greater than 600, or preferably no greater than 500 microns, or no greater than 400 microns. PAT 15705- WO-PCT

[0049] 8

[0050] In some embodiments, the water-soluble polymer film has a thickness of between 100- 700 microns, or between 100-600 microns, or preferably between 100-500 microns, or between 100-400, 100-300, 100-200, or preferably between 120-200 microns.

[0051] In one embodiment, the water-soluble polymer film has a thickness of between 100-500 microns, preferably of between 120-250 microns, and more preferably of between 140- 220 microns.

[0052] The water-soluble polymer film may be a cast, blown or extruded film. In some embodiments, the water-soluble polymer film may be a solution cast or a cast extruded film. The water-soluble polymer film may be a blown extruded film. The film may be unoriented, mono-axially oriented or bi-axially oriented.

[0053] Step (a) may comprise the step of preparing the water-soluble polymer film. Step (a) may comprise the step of preparing the water-soluble polymer film by a method independently selected from the group consisting of: solution cast, blown extrusion, and cast extrusion.

[0054] In some embodiments, the cast extrusion process in step (a) comprises the steps of: providing at least one water-soluble polymer resin into an extruder; optionally combining the at least one water-soluble polymer resin with at least one plasticizer in the extruder to form a mixture; extruding the mixture to form a water-soluble polymer composition; and forming the water-soluble polymer film from the water-soluble polymer composition.

[0055] In some embodiments, the step of extruding the mixture and the step of forming the water-soluble polymer film are combined into a single step of extruding the mixture to form the water-soluble polymer film.

[0056] In some embodiments, step (b) comprises contacting at least part of a surface of the film with water. Step (b) may comprise contacting at least 10% of the area of the surface of PAT 15705- WO-PCT

[0057] 9 the film with water, or at least 20, 40, 70, 95, or at least 99% of the area of the surface of the film. Step (b) may comprise contacting substantially 100% of the area of the surface of the film with water. Step (b) may comprise contacting no greater than 98% of the area of the film with water, or no greater than 90, or no greater than 80% of the area of the surface of the film.

[0058] Step (b) may comprise contacting the surface of the film with water uniformly. In other embodiments, step (b) may comprises contacting the surface of the film with water non- uniformly. In some embodiments, a centre portion of the film surface may be contacted with water to a greater extent than side portions of the film surface.

[0059] In embodiments in which the water-soluble polymer film comprises two opposing surfaces, step (b) may comprise contacting one or both surfaces of the film with water. In some embodiments, step (b) may comprise contacting only one of the surfaces of the film with water. Statements above relating to the area of the surface of the film that is contacted with water in step (b) may relate to only a single surface of the film or may relate to both surfaces of the film.

[0060] In some embodiments, the step of contacting the water-soluble polymer film with water in step (b) comprises submerging the water-soluble polymer film in water.

[0061] In some embodiments, at least 10% of the total outer surface area of the film is submerged in water, or at least 20, 50, 80, or at least 99% of the total outer surface area of the film is submerged in water. Substantially 100% of the total outer surface area of the film may be submerged water. In some embodiments, no greater than 98% of the total outer surface area of the film is submerged in water, or no greater than 90, or no greater than 80% of the total surface area of the film is submerged in water. PAT 15705- WO-PCT

[0062] 10

[0063] In some embodiments, the step of contacting the film with water in step (b) comprises applying water to the film, preferably to a surface thereof.

[0064] In some embodiments, the step of contacting the water-soluble polymer film with water in step (b) comprises contacting the water-soluble polymer film with a wet surface.

[0065] In some embodiments, the wet surface may comprise wet fabric surface. The wet surface may comprise a surface of a wet roller, which may be a fabric roller.

[0066] The film may be contacted with the surface of the wet roller by feeding a reel of or comprising the film past the roller. In some embodiments, the film may be contacted with the surface of the wet roller by feeding a reel of or comprising the film through a gap between the wet roller and a further roller, which may be wet or dry. In some embodiments, the film may be contacted with the surface of the wet roller by feeding a reel of or comprising the film through a gap between the wet roller and a plate, which may be wet or dry.

[0067] In some embodiments, the film is contacted with the wet surface at least once, or twice or at least twice, or thrice or at least thrice, or four times or at least 4 times, or five times or at least 5 times.

[0068] In some embodiments, the film is contacted with the wet surface for a time period of at least 0. 1 seconds, or at least 0.5 seconds. The film may be contacted with the wet surface for a time period of no greater than 10 seconds, or no greater than 5, or no greater than 1 second.

[0069] In some embodiments, the step of contacting the water-soluble polymer film with water in step (b) comprises coating the film with water. The step of contacting the water- PAT 15705- WO-PCT

[0070] 11 soluble polymer film with water in step (b) may comprise coating the film with droplets of water.

[0071] In some preferred embodiments, the step of contacting the water-soluble polymer film with water in step (b) comprises spray-coating the film with water. In such embodiments, step (b) may comprise spraying the film with a mist of water, preferably a mist of droplets of water.

[0072] In some embodiments, a reel of or comprising the film may be fed past a water sprayer and the water sprayer may spray the film with water as the reel is fed past the sprayer.

[0073] In some embodiments, step (b) may comprise applying water to or coating with water at least 10% of the total outer surface area of the film, or at least 20, 50, 90, or at least 99% of the total outer surface area of the film. Step (b) may comprise applying water to or coating with water substantially 100% of the total outer surface area of the film. In some embodiments, step (b) comprises applying water to or coating with water no greater than 98% of the total outer surface area of the film, or no greater than 90, or no greater than 80% of the total surface area of the film.

[0074] In some embodiments, step (b) comprises contacting the water-soluble polymer film with water to provide the film with a total water content of at least 5 wt. % of the film. Step (b) may comprise contacting the film with water to provide a film with a total water content of no greater than 20 wt.% of the film, or no greater than 15 wt.% of the film. Step (b) may comprise contacting the film with water to provide a film with a total water content of between 5-20 wt.% of the film, or between 5-15, or between 5-10 wt.% of the film.

[0075] In some embodiments, contacting the film with water in step (b) causes water to migrate into the film. PAT 15705- WO-PCT

[0076] 12

[0077] In some embodiments, the water used to contact the film in step (b) may be present as an aqueous solution.

[0078] In some embodiments, the water may be present as an aqueous solution of at least one acid, at least one sugar, and / or at least one sugar alcohol.

[0079] Examples for such a sugar suitable for the invention are glucose, fructose, galactose, sucrose, lactose and maltose.

[0080] Examples for such a sugar alcohol suitable for the invention are xylitol, mannitol, erythritol, threitol, arabitol, ribitol, galactitol, fucitol, iditol, inositol, volemitol, isomalt, maltitol, lactitol, maltotriitol, maltotetraitol, polyglycitol.

[0081] In some embodiments, the water may be present as an alkaline solution, such as sodium hydroxide; or of an acidic solution, such as hydrochloric acid.

[0082] In some embodiments, the water may be present as an aqueous mixture with sorbitol, glycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, neopentyl glycol, ethanolamines and / or ethanol.

[0083] In some embodiments, the step of thermoforming the wetted film in step (c) is performed at least 1 second after the step of contacting the film with water, or at least 5 seconds after the step of contacting the film with water, or at least 10 seconds after the step of contacting the film with water, or at least 1 minute after the step of contacting the film with water. The step of thermoforming the wetted film in step (c) may be performed no greater than 20 minutes after the step of contacting the film with water in step (b), or no greater than 10 minutes after the step of contacting the film with water, or no greater than 1 minute after the step of contacting the film with water, or no greater than 30 seconds after the step of contacting the film with water. The step of thermoforming the wetted PAT 15705- WO-PCT

[0084] 13 film in step (c) may be performed between 5 seconds to 20 minutes after the step of wetting the film with water in step (b), or between 5 seconds to 10 minutes, 5 seconds to 5 minutes, 5 seconds to 1 minute, or between 10 seconds to 30 seconds after the step of wetting the film with water in step (b).

[0085] The wetted film may be left to rest for the time periods above prior to thermoforming in step (c).

[0086] In some embodiments, the step of wetting the film with water in step (b) may be performed in a wetting station and the step of thermoforming the wetted film in step (c) may be performed in a forming station. After the step of wetting the film with water in step (b), the method may comprise the step of feeding a reel of or comprising the film from the wetting station to the forming station. In such embodiments, the distance between the wetting station and the forming station may be at least 0.12 m, or at least 0.6 m, or at least 1.2 m, or at least 6.6 m, or at least 7.2 m. The distance between the wetting station and the forming station may be no greater than 14,4 m, or no greater than 7.2 m, or no greater than 3.6 m. The distance between the wetting station and the forming station may be between 0.6-14,4 m, or between 0.6-72 m, 0.6-7.2 m, or between 1.2-3.6 m.

[0087] In some embodiments, the method further comprises at least one step of pre-heating the water-soluble polymer film before step (c).

[0088] At least one pre-heating step can advantageously encourage migration of water from the wetting step in step (b) into the film.

[0089] The method may comprise multiple pre-heating steps before step (c). The method may comprise 2 or at least 2 pre-heating steps before step (c). PAT 15705- WO-PCT

[0090] 14

[0091] In some embodiments, at least one step of pre-heating the film is performed before contacting the film with water in step (b). At least one step of pre-heating the film may be performed after contacting the film with water in step (b). At least one step of pre-heating the film may be performed before contacting the film with water in step (b) and at least one step of pre-heating the film may be performed after contacting the film with water in step (b).

[0092] In some embodiments, at least one step of pre-heating the film is only performed before contacting the film with water in step (b) and not after contacting the film with water. In other embodiments, at least one step of pre-heating the film is only performed after contacting the film with water in step (b) and not before contacting the film with water.

[0093] In embodiments in which the film is in the form of a sheet with two opposing surfaces, one or both surfaces of the film may be pre-heated. In some embodiments, only a single surface of the film is pre-heated. In some embodiments, only the surface of the film that is contacted with water in step (c) is pre-heated.

[0094] In some embodiments, at least one pre-heating step comprises heating the water-soluble polymer film to a temperature of at least 50 °C, or at least 70, or at least 100 °C. At least one pre-heating step may comprise heating the water-soluble polymer film to a temperature of no greater than 200 °C, or no greater than 180, or no greater than 150 °C. In some embodiments, at least one pre-heating step comprises heating the water-soluble polymer film to atemperature of between 50-200 °C, 70-170 °C, or between 80-150 °C, or between 100-140 °C, or between 110-130 °C.

[0095] In some embodiments, at least one pre-heating step comprises heating the water-soluble polymer film for at least 0. 1 seconds, or at least 1 second. In some embodiments, at least PAT 15705- WO-PCT

[0096] 15 one pre-heating step comprises heating the water-soluble polymer film for no greater than 5 minutes, or no greater than 1 minute, or no greater than 5 seconds. In some embodiments, at least one pre-heating step comprises heating the water-soluble polymer film for between 0.5-30 seconds, or between 0.5-20, or between 0.5-10, or between 1-10 seconds, or between 1-5 seconds.

[0097] In some embodiments, at least one pre-heating step comprises contacting the water- soluble polymer film, preferably a surface thereof, with a hot surface. The hot surface may be a metal surface. Alternatively, the at least one pre-heating step can be executed via hot air heating or via infrared heating. Contacting said film with a hot surface is preferred.

[0098] In some embodiments, the thermoforming step in step (c) comprises the steps of: softening the wetted water-soluble polymer film to produce a softened film; and forming the softened film.

[0099] In some embodiments, the step of softening the wetted film comprises heating the wetted film to a softening temperature.

[0100] The step of softening the wetted film may comprise heating the wetted film to a softening temperature of at least 50 °C, 70, or at least 100 °C. The softening step may comprise heating the wetted film to a softening temperature of no greater than 200 °C, or no greater than 180, or no greater than 150 °C. In some embodiments, the softening step comprises heating the wetted film to a softening temperature of between 50-200 °C, 75- 180 °C, or between 100-150 °C, or between 110-120 °C.

[0101] In some embodiments, the step of forming the softened film comprises subjecting the softened film to a vacuum. PAT 15705- WO-PCT

[0102] 16

[0103] In some embodiments, the step of forming the softened film comprises contacting the film with a mould to shape the film according to the shape of the mould.

[0104] The forming step may comprise contacting a surface of the film with the mould to shape the film according to the shape of the mould. Said surface may preferably have been contacted with water in step (b) of the method. Said surface may have been the only surface that was contacted with water in step (b) of the method. In other embodiments, said surface may not have been contacted with water in step (b) of the method, and the opposite surface of the film may have been the only surface that was contacted with water in step (b) of the method.

[0105] According to a second aspect of the invention, there is provided a method of manufacturing a water-soluble unit dose article, said article comprising at least one composition packaged in a container comprising a water-soluble polymer film, the method comprising steps (a) and (b) of the method of the first aspect of the invention, and further comprising the steps of:

[0106] (c) Thermoforming the wetted water-soluble polymer film to produce a thermoformed open water-soluble polymer film container, said container defining at least one internal compartment and comprising at least one opening to the at least one compartment;

[0107] (d) At least partially filling the at least one internal compartment of the thermoformed open water-soluble polymer film container with at least one composition; and

[0108] (e) Sealing the at least one opening of the open container to provide the water- soluble unit dose article. PAT 15705- WO-PCT

[0109] 17

[0110] Statements of invention for the first aspect of the invention above may also be applied mutatis mutandis to the second aspect of the invention.

[0111] Statements of invention below for the second aspect of the invention may also be applied mutatis mutandis to the other aspects of the invention.

[0112] The container may at least partially disperse, disintegrate or rupture when placed in water at 20 °C, preferably within 10 minutes, to allow for egress of the contents of the container into the water.

[0113] The thermoforming method may be performed as described for step (c) of the first aspect of the invention above. The open container may be provided in step (c) by thermoforming the wetted film to provide at least one pocket defining an internal compartment, as described for the first aspect of the invention above.

[0114] In some preferred embodiments, the container is a multi-compartment container. In such embodiments, step (c) may comprise thermoforming the wetted film to produce an open container comprising multiple compartments. In some embodiments, the open container may comprise an opening to each compartment. In other embodiments, the container may comprise a single opening to each compartment.

[0115] The multi-compartment container may comprise two or more, preferably three or more, separated compartments.

[0116] At least one composition may be a solid, liquid, or combinations thereof. “Liquid” may include free-flowing liquids, as well as pastes, gels, foams, and mousses. Gases, such as suspended bubbles, or solids, such as particles, may be included within the liquids. A “solid” may include, but is not limited to, powders, agglomerates, granules, microcapsules, beads, tablets, noodles, and balls. PAT 15705- WO-PCT

[0117] 18

[0118] In embodiments wherein the container is a multi-compartment container, step (d) may comprise at least partially filling each compartment of the container with at least one composition. In some embodiments, all compartments of the multi-compartment container are filled with the same composition. In other embodiments, at least two compartments of the multi-compartment container may be filled with different compositions. In some embodiments, all compartments of the multi-compartment container may be filled with a different composition. In some embodiments, all compartments of the multi-compartment container may be filled with a liquid composition, or all compartments of the container may be filled with a solid composition. In other embodiments, at least one compartment may be filled with a liquid composition and at least one compartment may be filled with a solid composition.

[0119] At least one composition may be independently selected from the group consisting of: a dishwashing composition, a water-softening composition, a laundry composition, a detergent composition, a rinse aid, and combinations thereof.

[0120] In some embodiments, at least one composition is an automatic dishwashing composition.

[0121] In some embodiments, the opening of the open container may be sealed in step (e) by sealing the open container to at least one other water-soluble polymer film.

[0122] In embodiments wherein the container is a multi-compartment container, a single further film may be sealed to the open container to seal the opening(s) to each compartment of the open container. Alternatively, multiple further films may be sealed to the open container to seal the container. In such embodiments, each further film may be sealed to PAT 15705- WO-PCT

[0123] 19 the open container to seal one or more openings to one or more compartments but not to all compartments.

[0124] Sealing may be performed by heat sealing. Heat sealing may be performed at a sealing temperature of between 120-195 °C.

[0125] Sealing may be performed using a sealing method independently selected from the group consisting of: infrared, radio frequency, ultrasonic, laser, solvent, vibration, electromagnetic, hot gas, hot plate, insert bonding, fraction sealing, and spin welding.

[0126] Sealing may be performed using an adhesive. The seal generated may be water-soluble.

[0127] The container of the water-soluble unit dose article may be independently selected from the group consisting of: a sachet, a bag, a pouch, and a packet.

[0128] Detailed Description of the Invention

[0129] In order that the invention may be more clearly understood, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0130] Figure 1 shows a graph of weight of a PVOH film piece in grams against time in minutes to show water uptake by the film after 1 and 2 swipes of the film with a wet roller (at time = 0).

[0131] Figure 2 shows a graph of water content in a PVOH film in wt.% against time in minutes to show water uptake by the film after 1 and 2 swipes of the film with a wet roller (at time = 0). PAT 15705- WO-PCT

[0132] 20

[0133] Figure 3 shows a graph of weight of a PVOH film piece in grams against time in minutes to show water uptake by the film after 2 swipes of the film on a wet microfibre towel (at time = 0).

[0134] Figure 4 shows a graph of water content in a PVOH film in wt.% against time in minutes to show water uptake by the film after 2 swipes of the film on a wet microfibre towel (at time = 0). assessment method

[0135] In all thermoforming examples below, forming behaviour and quality of a thermoformed film was assessed using the following method.

[0136] The film was formed into the target shape. A small spatula was pressed into the cavity over the whole area especially in narrow parts and deep comers. If the film was not flushed to the cavity, then the area was marked with a pen. Several points in the cavity were chosen for testing - a mixture of points at the curved edges and in the centre. The total number of reference points marked by the pen was counted, giving a forming score. The lower the score the more successful the forming of the film.

[0137] Effect of humidity on formability of water-soluble nolymer films

[0138] The inventors investigated the effect of humidity on the forming ability of water-soluble polymer films.

[0139] Cast extruded PVOH films (containing 75.4% PVOH, 22% plasticiser and 2.6% processing aids and antiblocking agents) were thermoformed (120 °C pre-heating for 2 seconds; forming vacuum: -930 mbar) to produce a thermoformed film comprising 3 compartments (mould cavity 1-3). PAT 15705- WO-PCT

[0140] 21

[0141] The forming ability of the films was tested at 22 °C and at two different humidities using the forming assessment method above. The different humidities tested were: 40% r.h. and 60% r.h.

[0142] The results of the forming ability tests are shown in Table 1 below. Table 1

[0143] The forming score was improved when the thermoformed film was tested at the higher humidity value.

[0144] At the higher humidity, the film takes up more water than at the lower humidity, which causes the film to become more flexible and display a better forming ability. This effect is caused by the hygroscopic nature of the film’s water-soluble polymer (such as PVOH). Water has a plasticising effect on the polymer and disrupts polymer-polymer hydrogen bonding networks, which increases polymer chain mobility, thus lowering the glass transition temperature, rendering the film more flexible. However, despite this property, thermoforming production processes have typically been restricted to being performed at ambient humidity levels, generally not exceeding 50% r.h., as the film would otherwise become too sticky and elastic to unwind from a reel and be transferred to a thermoforming line, potentially causing critical stoppages of the PAT 15705- WO-PCT

[0145] 22 process. Furthermore, dosing of detergent powders and other compositions at high humidity can cause filling and spilling issues as well.

[0146] Use of thick water-soluble polymer films (>100 microns)

[0147] Due to the increase amount of polymer material in thicker water-soluble polymer films, they can theoretically be drawn deeper than thinner films to fit larger amounts of composition. However, the thickness of the film has an effect on the softening and forming steps of a thermoforming process. A larger amount of material of must be heated to the softening temperature and a higher vacuum must be used as the thicker film requires a higher absolute force to be stretched and thermoformed. This can make the thermoforming process for thicker films highly energy intensive.

[0148] Surprisingly, the inventors have found that thicker films are sufficiently robust to be directly contacted with water, without displaying any negative effects of a higher moisture environment described above. When treated with water directly, thicker films were found to become more elastic and their softening temperatures in thermoforming were found to be significantly reduced, leading to a significant improvement in forming behaviour. The approach of treating thicker films directly with water was advantageously found to only marginally increase energy consumption, whilst an increase of pre-heating temperature and / or thermoforming cycle time would lead to a significantly elevated energy consumption.

[0149] Surprisingly, despite the additional elasticity / flexibility conferred by contacting thicker films with water, thermoformed products of the method of the invention were found to demonstrate an enhanced shrinking effect, especially when thermoforming was performed at lower temperatures. The thermoformed products were found to have a PAT 15705- WO-PCT

[0150] 23 larger memory effect, which is particularly useful when producing thermoformed containers. The elasticity provided by contacting the films with water allowed for greater stretching of the thermoformed containers, allowing greater amounts of compositions / ingredients to be inserted into the containers. The memory effect thereafter allowed the thermoformed container to shrink in width and length after composition / ingredient had been added to provide the container with minimal dimensions whilst still securely containing the desired amount of composition / ingredient. It is especially desirable to obtain a small, compact container for dosage chamber fit and release, especially in automatic washing applications, and for consumer preference.

[0151] Testing water uptake of thick PVOH films

[0152] Direct water application may be performed using a number of methods including: (i) water spraying; (ii) transporting the film over a wet roller; and (iii) applying water mist / vapour. For the experiments below, water application was performed by transporting films over a wet roller or by contacting films with a wet towel.

[0153] In a first set of trials, the amount of water added and retained to a film after different numbers of swipes of the film with a wet roller was measured. For this measurement, a piece of dry film was cut (37 mm x 45 mm) and the weight captured, then wetted and placed back on the analytic balance to monitor the weight change after time. The total water level in % was calculated based on a starting value of 3% which was determined by Karl-Fischer-Titration.

[0154] The PVOH film tested was produced using a cast extrusion process and a mix of two poly(vinyl alcohol) homopolymers (total % of PVOH: 73.5%) with a degree of PAT 15705- WO-PCT

[0155] 24 hydrolysis of 87-89%, 24% of plasticiser and 2.6% of processing aids and antiblocking agents. The thickness of the film was 150 pm.

[0156] Room conditions during testing were 22-23 °C and 44% r.h.

[0157] One and two swipes

[0158] Wet roller

[0159] Water uptake after 1 and 2 swipes of the PVOH film with a wet roller was measured with time and the results are displayed in the graphs of Figures 1 (water uptake measured in grams) and 2 (water uptake measured as wt. % of the film).

[0160] As can be seen from Figures 1 and 2, 2 swipe with the wetting roller adds more significantly to the water level of the film.

[0161] Using 2 swipes of the wet roller led to an increase of water in the film from 3 wt.% to 7.5-8.5 wt.%. The film surface was monitored for stickiness overtime, and was found to not be sticky on touch when touched 1 minute after contact with the wet roller, indicating that the water added to the surface of the film had migrated into the film.

[0162] After 16-20 minutes, no weight change could be detected, leading to final water levels of 5.3-6.2 wt.%.

[0163] Wet microfibre towel

[0164] Water uptake after 1 and 2 swipes of the PVOH film with a wet microfibre towel that was immersed in a water tub. Results were similar to that achieved when swiping the film with a wet roller, demonstrating that a range of wetting methods are possible.

[0165] Results are displayed in the graphs of Figures 3 (water uptake measured in grams) and 4

[0166] (water uptake measured as wt. % of the film). PAT 15705- WO-PCT

[0167] 25

[0168] Three and four swipes

[0169] Three and four swipes with a wet roller and wet microfibre towel were also tested.

[0170] Using 3 swipes with a wet roller, the water level reached 7.5 wt.%, and 5.5-5.8 wt.% after 20 minutes rest time. The wetted film surface was not sticky to touch after 1 minute rest time.

[0171] Using four swipes led to an initial water level of 9 wt.% after wetting, and 6.6 wt.% after 20 minutes - however, the film did begin to fold over itself in some parts of the wet surface.

[0172] In general, the experiments above demonstrated that water which was added to the PVOH film as a thin layer was able to migrate into the film within a few minutes, and that even after 20 minutes the level of water in the film remained higher than the original untreated film. Also, 1 -minute post- wetting, the film surface was no longer wet and sticky.

[0173] Heat treatment step before thermoforming

[0174] To understand if an additional pre-heating step prior to thermoforming would dry out the film, another set of experiments were carried out: Directly after wetting, the film was treated for 1 second at 120 °C by placing a hot metal surface on the film. The weight and calculated percentages were similar to the results of the previous wetting experiments. Also with heat treatment, the film retained the additional water for up to 20 minutes. Therefore, it was concluded that the added water was able to migrate into the film. PAT 15705- WO-PCT

[0175] 26

[0176] When pre-heating was performed after weting of the film, the hot surface was applied to the surface of the film which had not been weted with water. In other embodiments, the wetted surface may be contacted with the hot surface.

[0177] Thermoforming trials Based on the above experiments, thermoforming trials were carried out. Thermoforming was performed by heating the film to a softening temperature of 120 °C, and then forming the film using a vacuum of -930 mbar and subjecting the film to a mould comprising 3 depressions which defined 3 cavities. In embodiments wherein a surface of the film was weted, the weted side of the film was contacted with the mould. In other embodiments, the non-weted side of the film may be contacted with the thermoforming mould.

[0178] 150 micron thick PVOH films

[0179] Forming ability of the 150 micron thick PVOH film at different conditions was assessed using the method described above. Results are shown in Table 2. Table 2 PAT 15705- WO-PCT

[0180] 27 PAT 15705- WO-PCT

[0181] 28

[0182] The forming scores above clearly demonstrate that wetted films form significantly better than dry films. Even after a 5-minute waiting time, forming results for a wetted film remain significantly better than for a dry film. 180 micron thick PVOH films

[0183] Forming ability of a 180 micron thick PVOH film (comprised of 75.4% PVOH, 22% plasticiser, 2.6% processing aids and antiblocking agents) at different conditions was also assessed using the method described above. Results are shown in Table 3.

[0184] Table 3 PAT 15705- WO-PCT

[0185] 29 form significantly better than dry films. PAT 15705- WO-PCT

[0186] 30

[0187] Square mould testing

[0188] Forming assessment of 180 micron thick films thermoformed using square moulds with lengths of 15 mm and depths of: 6 mm, 12.5 mm, and 15.2 mm was carried out to understand the influence of wetting the film to draw it deeper. Thermoforming was performed as described above using a vacuum of -930 mbar, but using different softening temperatures of: 110 °C, 115 °C and 120 °C.

[0189] The results are displayed in Table 4 below.

[0190] Table 4 PAT 15705- WO-PCT

[0191] 31 PAT 15705- WO-PCT

[0192] 32

[0193] At 110 °C, wetting the film prior to thermoforming allowed for the complete forming of the film using a 12.5 mm deep mould, which otherwise incompletely formed using a dry film. As the thermoforming temperature was increased to 115 °C, there was still some incomplete forming of the 12.5 mm mould using a dry film, which when wetted, formed completely. Similar results were observed at 120 °C, where the forming of the comers of the 15.2 mm deep mould was improved with wetting.

[0194] Final thickness of thermoformed films

[0195] 3-compartment pouches were thermoformed by a method of the invention using 180 micron thick films, which were subjected to a wetting step prior to thermoforming. The final pouches had 3 compartments, independently used to hold a powder, gel and liquid composition, respectively.

[0196] To evaluate the forming results further, the thicknesses of the final thermoformed films were measured. Measurements were performed using an Olympus Magna Mike8600 with 1 / 16” target balls. The target balls were placed in the compartments of the formed pouches before a sealing film was applied to seal the pouches.

[0197] Thicknesses at 11 of the most critical points at the bottom and bottom comers of the compartments of the pouches were measured, as these are thinned out the most in the PAT 15705- WO-PCT

[0198] 33 thermoforming process. The thicknesses of the pouches at these 11 measuring points were measured three times and the average was calculated to determine if the values fall within the acceptable range for thermoformed films used to hold the respective composition. Table 5 below summarises the acceptable thickness range for holding the different composition types and the average calculated values for the 180 micron thick film which was thermoformed using the method of the invention. The acceptable thickness range was calculated by using the acceptable thickness range of a 90 micron thick film as the basis. Table 5

[0199] From the results, it is clear that the thicknesses of films thermoformed using the method of the invention by wetting prior to thermoforming are within the acceptable range and do not thin the film out of the limits at the bottom and bottom comers of the film. Improved shrink properties of films thermoformed using the method of the invention

[0200] The wetting of thick water-soluble polymer films prior to thermoforming was shown not only to lead to better forming behaviour, but pouches thermoformed using such a method PAT 15705- WO-PCT

[0201] 34 also advantageously displayed a higher shrink rate compared to pouches formed using methods of the prior art.

[0202] To test this, 3 tri-compartment pouches were prepared using a dry 180 micron PVOH film (thermoforming temperature 140 °C and 2 s heating; - 930 mbar thermoforming vacuum) and with a wetted film (wetting step: 3 swipes on wet microfibre towel; preheating for 5 s at 120 °C; thermoforming temperature 140 °C and 2 s heating; - 930 mbar thermoforming vacuum). The compartments of the pouches were respectively filled with powder, gel and liquid compositions and left for 4 days at room temperature in a plastic bag. The forming temperatures were chosen as the minimum temperatures at which a complete forming could be achieved.

[0203] After 4 days, the pouches were taken out of the bag and the compartment sizes measured using a calliper. The dimensions were measured without the outer sealing area to be able to compare with the compartment dimensions. The results of the width and length measurements of a compartment of pouches formed using the dry 180 micron thick film (control method), along with shrink values (in mm and %) after 4 days are displayed in Table 6 below.

[0204] Table 6 PAT 15705- WO-PCT

[0205] 35

[0206] From the results above, it is clearly visible that pouches prepared using the wetting method of the invention show a higher shrink in both directions compared to pouches prepared with a dry film. This advantageously allows for the preparation of a small compact pouch using the method of the invention. Summary and conclusions

[0207] Under the usual industrial conditions of temperature and pressure, the thick films (>100 microns) display poor forming ability. Adding water to the film by means of a wet roller and optionally pre-heating the film before the forming step has proven to increase the flexibility of the film, thus, improving forming behaviour. The amount of water retained PAT 15705- WO-PCT

[0208] 36 in the film after weting has been monitored by measuring the weight of the film with time. Various trials of forming with different numbers of water swipes, pre-heating times, heating before weting and vice versa have been carried out. Under all conditions, the wet film has proven to have significantly beter forming ability than dry thick films.

[0209] The wet films also cause additional shrinkage of the pouches, enabling them to fit easily in the dosage chambers of automatic dishwashing machines.

[0210] It is clear from the results of the experiments discussed in previous sections that the forming ability of thick films (>100 microns) can be significantly improved by weting and optionally heating the film before forming step, thereby increasing the flexibility of the film and the shrinking ability of resulting thermoformed containers. Unlike thin films, thick films have surprisingly been found to be robust enough to allow them to be directly treated with water. They do not dissolve in water, crumble or remain sticky after water application, especially 1 minute after water application. It has been found that water exists as a thin layer on the film and then migrates and remains inside the film, even after 20 mins of water application.

[0211] The weting technique of the invention allows water-soluble polymer films to be drawn deeper and pave the way to develop multi-compartment pouches with three or more compartments at lower forming temperatures and pressures, thereby reducing the effect of economic factors.

[0212] The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

PAT 15705- WO-PCT37CLAIMS1. A method of thermoforming a water-soluble polymer film, the method comprising the steps of: a. Providing a water-soluble polymer film having a thickness of at least 100 microns; b. Contacting the water-soluble polymer film with water to provide a wetted water-soluble polymer film; c. Thermoforming the wetted water-soluble polymer film.

2. A method as claimed in claim 1, wherein the water-soluble polymer film comprises polyvinyl alcohol, preferably in an amount of at least 50 wt.% of the film.

3. A method as claimed in any preceding claim, wherein the water-soluble polymer film has a thickness of between 100-500 microns, preferably of between 120-250 microns, and more preferably of between 140-220 microns.

4. A method as claimed in any preceding claim, wherein the water-soluble polymer film is a cast extruded film.

5. A method as claimed in any preceding claim, wherein the water-soluble polymer film comprises two opposing surfaces, and step (b) comprises contacting one or both surfaces of the polymer film with water.

6. A method as claimed in any preceding claim, wherein the step of contacting the water-soluble polymer film with water in step (b) comprises contacting thePAT 15705- WO-PCT38 water-soluble polymer film with a wet surface; wherein preferably the wet surface comprises a surface of a wet roller.

7. A method as claimed in any one of claims 1 to 5, wherein the step of contacting the water-soluble polymer film with water in step (b) comprises coating the film with water, preferably spray-coating the film with water.

8. A method as claimed in any one of claims 1 to 5, wherein the step of contacting the water-soluble polymer film with water in step (b) comprises submerging the water-soluble polymer film in water.

9. A method as claimed in any preceding claim, wherein step (b) comprises contacting the water-soluble polymer film with water to provide the film with a total water content of at least 5 wt.%, preferably of between 5-20 wt.%, more preferably of between 5-15 wt.%, and most preferably of between 5-10 wt.%.

10. A method as claimed in any preceding claim, wherein the step of thermoforming the wetted film in step (c) is performed at least 1 second after the step of contacting the film with water in step (b).

11. A method as claimed in any preceding claim, wherein the at least one step of pre-heating the water-soluble polymer film is performed before and / or after contacting the film with water in step (b); wherein the at least one pre-heating step preferably comprises heating the water-soluble polymer film to a temperature of between 80-150 °C, in particular for at least 0.1 seconds.

12. A method as claimed in claim 11, wherein the at least one pre-heating step comprises contacting the water-soluble polymer film with a hot surface or viaPAT 15705- WO-PCT39 hot air heating or via infrared heating, preferably via contacting said film with a hot surface.

13. A method as claimed in any preceding claim, wherein the thermoforming step in step (c) comprises the steps of: softening the wetted water-soluble polymer film to produce a softened film; and forming the softened film; wherein the step of softening the wetted water-soluble polymer film preferably comprises heating the wetted film to a softening temperature, preferably of between 100- 150 °C; and wherein the step of forming the softened film in particular comprises subjecting the softened film to a vacuum.

14. A method as claimed in claim 13, wherein the step of forming the softened film comprises contacting the film with a mould to shape the film according to the shape of the mould; preferably wherein the step of forming the softened film comprises contacting a surface of the film with the mould to shape the film according to the shape of the mould, wherein said surface of the film was contacted with water in step (b).

15. A method of manufacturing a water-soluble unit dose article, said article comprising at least one composition packaged in a container comprising a water-soluble polymer film, the method comprising steps (a) and (b) of the method of any preceding claim, and further comprising the steps of: c. Thermoforming the wetted water-soluble polymer film to produce a thermoformed open water-soluble polymer film container, said container defining at least one internal compartment and comprising at least one opening to the at least one compartment;PAT 15705- WO-PCT40 d. At least partially filling the at least one internal compartment of the thermoformed open water-soluble polymer film container with at least one composition; and e. Sealing the at least one opening of the open container to provide the water-soluble unit dose article.

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