WO2022017974A1

WO2022017974A1 - Casein based multilayer film with improved barrier properties

Info

Publication number: WO2022017974A1
Application number: PCT/EP2021/069945
Authority: WO
Inventors: Andreas Schroeder; Benjamin SCHMIDT-HANSBERG; Jessica Neumann; Jochen Eckhard WILLERSINN; Juergen Detering; Anja Weiland; Mireia SUBINYA ALBRICH; Matthias Laubender; Matthias Maase; Robert Parker
Original assignee: Basf Se
Priority date: 2020-07-24
Filing date: 2021-07-16
Publication date: 2022-01-27

Abstract

This invention relates to casein based multilayer films with improved barrier properties, their manufacture and uses.

Description

Casein based multilayer film with improved barrier properties

In the laundry and detergent industry, there is a demand for materials to encase laundry or detergent formulations, in particular liquid laundry formulations. For example, liquid detergent concentrates used in so called single unit dose products are currently in the focus of the laundry and detergent industries. In order to make single unit dose laundry or detergent products, materials are needed which are, on the one hand, stable at room temperature against decomposition and can be used to ensheath the liquid laundry or detergent formulations, and are, on the other hand, water soluble (at least at elevated temperatures), so they can release the laundry or detergent formulation when needed.

It is known that water-soluble films of polyvinyl alcohol can be used for packaging of washing and cleaning compositions in liquid, gel and solid form as portions. The polyvinyl alcohol film dissolves at the start of the washing and cleaning process and releases the washing and cleaning compositions, and so they are able to display their effect. The advantages of the washing and cleaning compositions packaged as portions (called single dose units or mono dose units) for the consumer are manifold. These include the avoidance of incorrect dosages, ease of handling, and the fact that the consumer does not come into physical contact with the constituents of the washing and cleaning compositions. These additionally also include esthetic aspects which lead to a preference for the washing and cleaning compositions packaged as portions. Current dosage forms can comprise a large number of separately formulated active ingredients and auxiliaries which are released individually in the cleaning process. Such multichamber systems permit, for example, the separation of incompatible constituents and hence the creation of new formulation concepts. The proportion of the polyvinyl alcohol film in the total weight of the washing or cleaning composition portion (single dose unit) is between 2% and 20% by weight, according to the application.

In the recent past, there has been an increased demand in the laundry and detergent industry for biobased and/or biodegradable materials. Polyvinyl alcohol, referred to above, is biodegradable, but not biobased. Customers from the laundry and detergent industry are, however, increasingly frequently asking for film materials which are both biobased and biodegradable.

Materials based on casein, a milk protein, are in principle known.

For example, WO 2019/122726 A1 describes a thermoplastic material made from casein and/or caseinate. In particular, a thermoplastic material comprising a) between 50 and 80% of casein and/or caseinate, b) between 4 and 12% of water, c) between 10 and 35% of at least one plasticiser different to b), d) between 0.1 and 8% of a hydrophobic agent, and e) between 0.5 and 6% of at least one surfactant is disclosed.

These materials are both biobased and biodegradable. Also known from WO 2019/122726 A1 are water soluble films based on casein.

However, the casein-based water-soluble films as described in WO 2019/122726 A1 have poor barrier properties against liquid detergent concentrates used in so called single unit dose products making such films unsuitable for liquid detergent products.

Thus, there was a need to provide water-soluble films, composed at least partially of biobased and/or biodegradable materials, which can be used successfully for ensheathing laundry or detergent compositions, in particular (concentrated) liquid laundry or detergent compositions. There was also a specific need to provide water-soluble films, based (at least partially) on casein, which can be used successfully for ensheathing laundry or detergent compositions, in particular (concentrated) liquid laundry or detergent compositions.

Summary of the invention

The inventors have now surprisingly found a solution for improved barrier properties against liquid detergent concentrates of such casein-based films, by adding a barrier layer, composed of a suitable material.

The multilayer approach allows the separation of the barrier problem into at least two discrete layers of different chemical composition. With this strategy a relatively thin barrier layer L2 of about 5 to 30 pm on top of the casein-based layer L1 of about 30 to 120 pm improves resistance against liquid detergent concentrates dramatically (over-proportional to thickness increase). The barrier layer may advantageously be composed of polyvinylalcohol of different molecular weight and degree of hydrolysis, gelatin of different bloom grades or various types of pectin (and mixtures thereof). Other materials may also be used for the barrier layer, for example biobased materials selected from sodium alginate, locust bean gum, xanthan, gelatin succinated, gellan gum (and mixtures thereof).

Glycerol is a preferred option as a plasticizer (independently from each other in both layers).

The multilayer approach is a preferred option for improving barrier properties against liquid detergent concentrates.

To make the multilayer film, two preferred procedures have been worked out.

The casein-based film can be laminated with the separately prepared barrier film by using an adhesive (optional additional film layer L3), or in case the barrier film delivers adhesive properties itself (e.g. by wetting the contact surface carefully with water), both films can be laminated by using the right amount of pressure, without addition of a further layer L3.

The multilayer concept retains a high fraction of bio-based materials ( > 60 wt%, preferably > 70 wt%, more preferably > 80 wt%, most preferably > 90 wt%) and at the same time provides a good resistance against liquid detergent concentrates, making the resulting films suitable for liquid detergent single unit dose products.

Thus, in one aspect, the present invention relates to a multilayer film comprising at least one film layer L1, comprising at least 40% by weight casein and/or caseinate, relative to the total weight of film layer L1 , and at least one film layer L2, wherein film layer L2 contains less than 10% by weight casein and/or caseinate, relative to the total weight of film layer L2.

Furthermore, the present invention also relates to a process for producing an inventive multilayer film, wherein film layers 1 and 2 are laminated together, optionally in the presence of a film layer L3.

The present invention also relates to the use of an inventive multilayer film for at least partial ensheathing of a solid, gel or liquid washing or cleaning composition.

In an embodiment of the invention, the multilayer film is not penetrated for a period of at least 48 hours by a detergent composition containing (a) between 15% by weight to 60% by weight anionic surfactants, (b) between 10% by weight to 40% by weight nonionic surfactants and (c) water, each relative to the total weight of the detergent composition.

“Penetrated” in the context of this invention means that the film is (i) swollen, tacky and feels wet and smeary, or (ii) that a first droplet of detergent composition leaks out

Detailed description of the invention

A "multilayer film" in the context of the invention is understood to mean a film composite where at least two films are permanently and fully bonded over a significant portion of their area. This is understood to mean that at least two films are permanently and fully bonded over at least 50% of their area. When two films of different size are bonded to one another, at least the film having the smaller area is permanently and fully bonded over at least 50% of its area. Thus, the multilayer films of the invention differ from known films for washing and cleaning composition portions where an individual film or 2 or more films are joined to one another by at least one weld seam. The latter films are permanently and fully bonded to one another over at most 10% of their area.

The term "multilayer film" in the context of the present invention refers to a self-supporting flat structure having at least two film layers. The maximum thickness of the multilayer films of the invention is preferably at most 200 pm, more preferably at most 150 pm, especially at most 120 pm.

The multilayer films of the invention have an essentially two-dimensional extent. The length and/or width of the film is generally at least 5 mm and preferably at least 10 mm. The maximum length and/or width of the film is generally uncritical and may be in the millimeter, centimeter or meter range.

In an embodiment of the present invention, layer L1 has a thickness of 20 to 150 pm, preferably 30 to 120 pm, and/or layer L2 has a thickness of 3 to 50 pm, preferably 5 to 30 pm, determined preferably by means of a digital gauge over an average of at least 10 measurement positions per film.

The multilayer films of the invention or those produced by the process of the invention are suitable for packaging of washing and cleaning compositions in liquid, gel and solid form as portions. They dissolve at the start and/or in the course of the respective use (for example in the washing or rinse water), thus release the constituents of the washing and cleaning composition.

In the context of the present invention, the terms "washing composition portion" and "cleaning composition portion" are understood to mean an amount of a washing composition or cleaning composition sufficient for a washing or cleaning operation that takes place in an aqueous phase. This may, for example, be a machine washing operation as conducted with commercial washing machines. According to the invention, this term is also understood to mean an active ingredient portion for a manual washing operation or a manually conducted cleaning operation (as conducted, for example, in a handwash basin, a sink or a bowl).

“Water soluble” in the context of this invention refers to the dissolution of the film layers in water at temperatures below 35 °C and normal pressure (1.01325 bar) within a limited time (dissolution time < 20 min, preferably < 15 minutes, most preferably < 10 minutes).

The film layer L1 comprises at least 40% by weight casein and/or caseinate, relative to the total weight of film layer L1.

Film layer L1 may comprise at least 45 % by weight casein and/or caseinate, preferably at least 50% by weight, more preferably at least 60% by weight, each relative to the total weight of film layer L1.

Casein is a family of related phosphoproteins (aS1 , aS2, b, k). These proteins are usually found in mammalian milk, and comprise approx. 80% of the proteins in cow's milk. The most common form of casein is sodium caseinate. Molar masses of casein may be in the range from 19000 to 25000 g/mol.

Film layer L1 preferably also contains at least one plasticizer. Suitable plasticizers for film layer L1 are described below.

In one embodiment, film layer L1 comprises or consists of (i) 50 to 80 weight-% casein and/or caseinate, preferably 52 to 75% by weight, more preferably 55 to 70% by weight, even more preferably 60 to 65% by weight, (ii) 4 to 13 weight-% water, preferably 4.5 to 12% by weight, more preferably 5% to 11% by weight, even more preferably 7% to 10.5% by weight, (iii) 10 to 35 weight-% plasticizer different from (b), preferably 12 to 32% by weight, more preferably 15 to 28% by weight, even more preferably 20 to 25% by weight, (iv) 0.1 to 8 weight-% hydrophobic agent, preferably 0.5% to 6% by weight, more preferably 1 to 4% by weight, even more preferably 1 to 3% by weight, and (v) 0.5 to 6% surfactant, preferably 1 to 5% by weight, more preferably 1.5 to 4.5% by weight, even more preferably 2 to 4% by weight.

Film layer L1 is preferably water-soluble.

The plasticizer (iii) in an embodiment of film layer L1 may be selected from polyols, glycerol, glycerol acetates, glycerol propionates or mixtures thereof, preferably glycerol.

The hydrophobic agent (iv) in an embodiment of film layer L1 may be selected from polycarboxylic esters, C3 to C33 polycarboxylic acids, preferably C4 to C28 fatty acids (for example oleic acid), particularly unsaturated C6 to C28 fatty acids, and mixtures thereof.

The optional surfactant (v) in an embodiment of film layer L1 may be selected from zwitterionic surfactants with a hydrophilic-lipophilic balance between 2 and 8, and mixtures thereof.

“Barrier layer” (film layer L2)

Film layer L2 preferably contains less than 5% by weight casein and/or caseinate, more preferably does not contain any casein or caseinate at all.

In a preferred embodiment, film layer L2 comprises or consists of at least one material selected from polyvinylalcohol, gelatin, pectin or mixtures thereof,

In a specially preferred embodiment, film layer L2 comprises mixtures containing polyvinylalcohol, more preferably (only) polyvinylalcohol.

As mentioned above, film layer L2 (also called “barrier layer” in the context of this invention) may contain polyvinyl alcohol.

Partly or fully hydrolyzed polyvinyl acetates (PVAs) are generally referred to as "polyvinyl alcohol (PVOH)". Partly hydrolyzed polyvinyl acetates are obtained by incomplete hydrolysis of polyvinyl acetates, meaning that the partly hydrolyzed polymer has both ester groups and hydroxyl groups. The hydrolysis of the polyvinyl acetates can be effected in a manner known per se under alkaline or acidic conditions, i.e. with addition of acid or base or via transesterification.

The performance properties of polyvinyl alcohols are determined by factors including the polymerization level and the hydrolysis level (level of hydrolysis). With rising hydrolysis level, the water solubility decreases. Polyvinyl alcohols having hydrolysis levels up to about 90 mol % are generally soluble in cold water. Polyvinyl alcohols having hydrolysis levels of about 90 to about 99.9 mol % are generally no longer soluble in cold water but are soluble in hot water.

Suitable polyvinyl alcohols preferably have a hydrolysis level of 50 to 99.9 mol %, more preferably of 70 to 99 mol %, especially of 80 to 98 mol %. Suitable polyvinyl alcohols preferably have a weight-average molecular weight of 10 000 to 300 000 g/mol, more preferably of 15 000 to 250 000 g/mol. Suitable polyvinyl alcohols preferably have a viscosity of 2 to 120 mPa s, more preferably of 7 to 70 mPa s and especially of 15 to 60 mPa s, measured to DIN 53015 on a 4% solution in water.

Polyvinylalcohol that can typically be used are known under the tradename Poval™ from Kuraray company. Non limiting examples are Poval™ 8-88, Poval™ 18-88, Poval™ 26-88, Poval™ 30-92, Poval™10-98, Poval™ 20-98 or Poval™ 28-99.

A special embodiment are copolymers comprising polyvinylalcohol repeat units and repeat units of at least one anionically modified monomer. Suitable classes of anionically modified monomers comprise monocarboxylic acid vinyl monomers, their esters and anhydrides, dicarboxylic monomers having a polymerizable double bond, their esters and anhydrides, vinyl sulfonic acid monomers, and alkali metal salts of any of the foregoing. Examples of suitable anionically modified monomers are vinyl acetic acid, maleic acid, monoalkyl maleate, dialkyl maleate, monomethyl maleate, dimethyl maleate, maleic anhydride, fumaric acid, monoalkyl fumarate, dialkyl fumarate, (in particular monomethyl fumarate and dimethyl fumarate), fumaric anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride, vinyl sulfonic acid, allyl sulfonic acid, ethylene sulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 2- acrylamido-2-methylpropanesulfonic acid, 2-methylacryl-amido-2-methylpropanesulfonic acid, 2- sufoethyl acrylate, alkali metal salts of the foregoing (e.g., sodium, potassium, or other alkali metal salts), esters of the foregoing (e.g., methyl, ethyl, or other Ci-C₆ alkyl esters), and combinations thereof (e.g., multiple types of anionic monomers or equivalent forms of the same anionic monomer). In a preferred embodiment, the anionically modified monomer is selected from 2-acrylamido-1-methylpropanesulfonic acid, 2-acrylamido-2- methylpropanesulfonic acid, 2- methylacrylamido-2-methylpropane-sulfonic acid, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride and the alkali metal salts thereof. The level of incorporation of the one or more anionically modified monomer units in the PVOH copolymers is not particularly limited. In a suitable embodiment, the one or more anionically modified monomer units are present in the PVOH copolymer in an amount in a range of about 2 mol% to about 10 mol%. To tune the performance properties according to the specific need of the application blends comprising polyvinylalcohols of different molecular weight and degree of hydrolysis can be used. Suitable blends are selected from a blend of at least two different polyvinylalcohol homopolymers, a blend of at least two different polyvinylalcohol copolymers, a blend of at least one polyvinylalcohol homopolymer and at least one polyvinylalcohol copolymer. Suitable polyvinylalcohol copolymers for the blends are those mentioned above.

Non limiting examples of blends of polyvinylalcohol homopolymers are a blend of Poval™ 26-88 (three parts) and Poval™ 20-98 (one part) or a blend of Poval™ 30-92 (two parts) and Poval™ 10-98 (one part).

As mentioned above, film layer L2 may also contain biobased materials, like (preferably) gelatin and/or pectin. Other biobased materials may also be used, for example sodium alginate, locust bean gum, xanthan, gelatin succinated, gellan gum (and mixtures thereof).

Gelatin is a mixture of compounds from animal proteins. Main component is denaturized or, respectively, hydrolysed collagen, produced from the connective tissue of various animals, mainly pigs and cattle.lt may also be referred to as hydrolyzed collagen, collagen hydrolysate, gelatine hydrolysate, hydrolyzed gelatine, and collagen peptides after it has undergone hydrolysis.

Bloom is a test to measure the strength of a gel or gelatin. The higher a Bloom value, the higher the melting and gelling points of a gel, and the shorter its gelling times.

Pectin is a naturally occurring polysaccharide found in berries, apples and other fruit. Its main building block is galacturonic acid, a sugar acid derived from galactose.

Both film layers L1 and L2 may, independently from each other, contain a plasticizer.

Suitable plasticizers for film layers L1 and L2 are, independently selected from each other and without limitation, alkyleneamines, alkanolamines, polyols such as alkylene glycols and oligoalkylene glycols, e.g. 2-methylpropane-1 ,3-diol, 3-methylpentane-1 , 5-diol, hydroxypropylglycerol, neopentyl glycol, alkoxylated glycerol (for example Voranol® from Dow Chemicals), water-soluble polyesterpolyols (for example TriRez from Geo Specialty Chemicals) and mixtures thereof. Suitable plasticizers are also polyetherpolyols available under the Lupranol® name from BASF SE. The term "alkyleneamines" refers to condensation products of alkanolamines with ammonia or primary amines; for example, ethyleneamines are obtained by reaction of monoethanolamine with ammonia in the presence of a catalyst. This results in the following main components: ethylenediamine, piperazine, diethylenetriamine and aminoethylethanolamine.

Preferably, the plasticizers are selected from glycerol, diglycerol, propylene glycols having a weight-average molecular weight of up to 400 g/mol, ethylene glycol, polyethylene glycols having a weight-average molecular weight of up to 400 g/mol, diethylene glycol, triethylene glycol, tetraethylene glycol, sugar alcohols such as sorbitol, mannitol, xylitol, isomalt, lactitol, isopentyldiol, neopentyl glycol, trimethylolpropane, diethylenetriamine, triethylenepentamine, triethanolamine and mixtures thereof.

Preference is given to multilayer films in which at least one of the layers includes an additive. Particular preference is given to multilayer films in which at least one of the layers includes an additive which is a constituent customary for washing and cleaning compositions. In that case, the additive is preferably selected from nonionic, anionic, cationic and amphoteric surfactants, builders, complexing agents such as methylglycinediacetic acid, glutamine-diacetic acid, glutamic acid diacetic acid and citric acid and the sodium and potassium salts thereof, bleaches, enzymes, enzyme stabilizers, bases, corrosion inhibitors, defoamers and foam inhibitors, wetting agents, dyes, pigments, fragrances, fillers, tableting aids, disinter-grants, thickeners, solubilizers, organic solvents, electrolytes, pH modifiers, perfume carriers, bitter substances, fluorescers, hydrotropes, antiredeposition agents, optical brighteners, graying inhibitors, antishrink agents, anticrease agents, dye transfer inhibitors, antimicrobial active ingredients, antioxidants, anti yellowing agents, corrosion inhibitors, antistats, ironing aids, hydrophobizing and impregnating agents, antiswell and antislip agents, plasticizers, scavengers, agents for modification of gas permeability and water vapor permeability, antistats, glidants, slip agents, UV absorbers and mixtures thereof.

In a preferred embodiment, one layer of the multilayer film of the invention comprises at least one enzyme as additive.

Suitable enzymes may be selected from the group consisting of proteases, amylases, lipases, cellulases, perhydrolases, mannanases, nucleases, peroxidases, oxidases, lyases, pectinases, arabinases, galactanases, xylanases, and mixtures thereof. Suitable enzyme stabilizers may be selected from calcium ions, boric acid, boronic acid, propylene glycol and short chain carboxylic acids, preferably selected from monocarboxylic acids with 1 to 3 carbon atoms per molecule and from dicarboxylic acids with 2 to 6 carbon atoms per molecule.

The washing, cleaning or dishwashing compositions of the invention may comprise at least one bitter substance. Bitter substances are specially used in order to prevent inadvertent swallowing of the compositions, for example by infants. Suitable bitter substances are known to those skilled in the art. These include, for example, denatonium benzoate (benzyldiethyl-(2,6- xylylcarbamoyl)methylammonium benzoate), the bitterest-tasting substance known to date, which is commercially available under the Bitrex® name.

Some additives can fulfill more than one function, for example as solvent and as plasticizer.

In order to make the multilayer films of the invention more flexible, plasticizers can be added thereto in the course of production. For production of the free-flowing compositions capable of film formation, preferably 0.5% to 80% by weight, more preferably 2% to 50% by weight and especially 3% to 30% by weight of plasticizer is used, based on the total weight of the composition.

Film layer L2 is preferably water-soluble.

Optional film layer L3

As mentioned above and also below, in one embodiment of this invention, an additional film layer L3 may be added between layers L1 and L2.

Film layer L3 is preferably water-soluble.

Layer L3 may be selected from adhesives, preferably from adhesives based on polyurethane, casein, gelatin or mixtures thereof, more preferably adhesives based on polyurethane Layer L3 preferably has a thickness of 2 to 10 pm, more preferably 3 to 8 pm, determined preferably by means of a digital gauge over an average of at least 10 measurement positions per film.

Film processing

As stated above, the film production process is not subject to any particular restrictions and the person skilled in the art is able to apply any desired production process of which he is aware on account of his art knowledge. The same applies to the production of sheaths and coatings based on a multilayer film of the invention. Particularly suitable methods are self-metered or pre metered coating methods, casting methods and extrusion methods.

The inventive multilayer films may advantageously be manufactured by additionally using lamination techniques.

As mentioned at the outset, the multilayer film can be produced by a lamination method. Lamination methods in which two or more film layers are bonded to one another over their area are known to those skilled in the art. Lamination involves pressing two or more than two films together under elevated pressure and/or at elevated temperature. As likewise mentioned at the outset, the multilayer film can also be produced by a simultaneous multilayer casting or co extrusion method. In addition, the multilayer film can also be produced by using combinations of the aforementioned production methods and the application method described hereinafter.

In a preferred embodiment, the multilayer film is produced by a process in which at least one free-flowing composition capable of film formation is applied to a carrier material.

Suitable carrier materials are firstly all materials which enable simple detachment of the finished multilayer film. Examples of these include glass, metals such as galvanized steel or stainless steel, polymers such as silicones or polyethylene terephthalate, siliconized polyethylene terephthalate, polymer-coated paper, such as silicone paper, etc. Suitable carrier materials are secondly monolaminar or multilaminar polymer films which remain as film layers in the multilayer film of the invention.

In a further specific embodiment, the production of the multilayer film proceeds on a carrier material which already comprises the first film layer and optionally also already comprises further film layers of the multilayer film. In other words, a carrier material which already comprises the first film layer and optionally further film layers of the multilayer film is used. In this case, the carrier material forms part of the multilayer film and remains in the multilayer film after the application of all the further layers. This means that the further layers applied to the carrier material are not subsequently detached again from the carrier material.

The viscosity of the free-flowing composition is matched to the technical demands of the production method and is determined by factors including the concentration of the components capable of film formation, the solvent content (water), the additives added and the temperature. The free-flowing compositions capable of film formation are applied in steps generally by means of standard methods, for example by means of methods selected from airblade coating, knife coating, airknife coating, squeegee coating, impregnation coating, dip coating, roll coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, flow coating, cascade flow coating, cascade coating, mono- and multilayer slide coating, curtain coating, mono- and multilayer slot die coating, spray coating, spin coating, or printing methods such as relief printing, intaglio printing, rotogravure printing, flexographic printing, offset printing, inkjet printing, letterpress printing, pad printing, heatseal printing or screenprinting methods. The application can also be continuous or semicontinuous, for example when the carrier material is moving, for example a permanently or intermittently moving belt.

The increase in viscosity can be effected by means of standard methods and generally depends on the form in which the free-flowing compositions capable of film formation have been applied.

If they have been applied as a melt, for example, there is generally already an increase in viscosity in the course of cooling. The cooling can be effected by simply leaving the carrier material to stand or by active cooling, such as cooling of the carrier material, jetting with a cool gas (jet), cooling in a cold room refrigerator and the like. If the free-flowing composition capable of film formation has been applied in the form of a solution or dispersion, it is generally necessary to remove at least some of the solvent, which can be effected, for example, by simply leaving the carrier material to stand, drying with an air jet or hot air jet, drying in drying cabinets, heating of the carrier material, application of a reduced pressure, optionally with simultaneous supply of heat, IR irradiation, microwave radiation, for example in a corresponding oven, and the like

In a preferred embodiment one layer is applied by solution casting on a polymer carrier foil. In subsequent film drying the residual moisture is adjusted in a way such that a freestanding second film can be laminated in a subsequent process step onto the layer which was cast onto the polymer carrier foil. In a further preferred embodiment, a steel belt is used as carrier material.

In another preferred embodiment one layer is applied by solution casting on a polymer carrier foil. After a subsequent drying step, another layer of lamination adhesive is applied on top of the previously cast layer. After drying of the lamination adhesive layer to an appropriate residual moisture a second film is laminated in a subsequent process step onto the adhesive interface. In a further preferred embodiment, a steel belt is used as carrier material.

The solvent of the free-flowing compositions is preferably selected from water, ethanol, n-propanol, isopropanol, ethylene glycol, diethylene glycol, 1 ,2-propylene glycol, 1,2-dipropylene glycol and mixtures thereof. In a specific embodiment, the solvent used is selected from water and a mixture of water and at least one solvent other than water, selected from ethanol, n- propanol, isopropanol, ethylene glycol, diethylene glycol, 1 ,2-propylene glycol, 1,2-dipropylene glycol and mixtures thereof.

Post processing

It is additionally possible to subject at least one surface or both surfaces of the multilayer films of the invention to at least partial coating with at least one additive. Such a treatment may serve, for example, to provide the surface with particular properties, such as nonstick action, antistatic action, hydrophilic or hydrophobic properties, etc. It is thus possible to provide the multilayer films, for example, with better detachment properties from the carrier material used in the production, better roll-off properties, better glide properties, reduced tack, better compatibility with particular components ensheathed or coated therewith, etc. According to the nature and formulation of the additive, the application can be effected by standard methods, for example by spraying, dipping, powder application, etc. Suitable additives for coating of the surface of the multilayer films of the invention are, for example, talc, surfactants such as silicone-containing surfactants, waxes, etc.

Printing or embossing of the multilayer films of the invention is also possible, in order to provide these, for example, with patterns, motifs, or inscriptions. The printing may follow the production of the multilayer film or be effected in an intermediate step during the buildup of the layers. This printing step preferably follows directly inline after the film production, in a separate printing or converting process, or inline with the pod production. Suitable printing methods are inkjet printing, and also intaglio and planographic printing methods such as flexographic printing, gravure printing, offset printing or inkjet printing.

Application of multilayer film

The multilayer films of the invention are generally thermoplastic and can be subjected to a forming operation by thermoforming (i.e. hot forming, deep drawing or vacuum deep drawing). A process for producing watersoluble film packagings by a thermoforming process which comprises a hot forming or deep drawing step is described in WO 00/55044.

For production of film portions, the multilayer film of the invention can be processed in a suitable manner, for example by cutting to a desired size and/or folding to form compartments. Subsequently, the edges can be sealed by standard sealing methods such as heat sealing, liquid sealing or pressure sealing.

The multilayer films of the invention are also advantageously suitable for production of what are called multichamber systems. Multichamber systems have 2, 3, 4, 5 or more than 5 chambers which each comprise a single component or a plurality of components of a washing or cleaning composition. This may in principle be a single washing- or cleaning-active ingredient, a single auxiliary or any desired mixture of two or more than two active ingredients and/or auxiliaries. The constituents of the individual chambers may each be in liquid, gel or solid form. Multichamber systems are an option, for example, in order to separate components of a washing or cleaning composition that are incompatible or not very compatible from one another. For example, one chamber may comprise one or more enzyme(s) and another chamber at least one bleach. Multichamber systems are also an option, for example, in order to facilitate controlled release of a particular component, for example at a certain time point in the washing or cleaning operation. For this purpose, for example, it is possible to use film materials of different material thickness.

In addition, individual chambers can be produced using a multilayer film of the invention and others using a different conventional film.

In the context of the present invention, washing compositions are understood to mean those compositions which are used for cleaning of flexible materials having high absorptivity, for example of materials having a textile character, whereas cleaning compositions in the context of the present invention are understood to mean those compositions which are used for cleaning of materials having a closed surface, i.e. having a surface which has only few small pores, if any, and as a result has only low absorptivity, if any.

Examples of cleaning compositions which may comprise the washing- and cleaning-active multilayer film of the invention include washing and cleaning compositions, dishwashing compositions such as manual dishwashing compositions or machine dishwashing compositions (=dishwashing composition for the machine dishwasher), metal degreasers, glass cleaners, floor cleaners, all-purpose cleaners, high-pressure cleaners, neutral cleaners, alkaline cleaners, acidic cleaners, spray degreasers, dairy cleaners, commercial kitchen cleaners, machinery cleaners in industry, especially the chemical industry, cleaners for carwashing and also domestic all-purpose cleaners.

The washing or cleaning compositions of the invention may also be portions of washing or cleaning compositions in solid, liquid or gel form packaged in pouches. In a specific embodiment, these are called pouches (liquid tabs). The products may also be compressed shaped bodies such as tablets ("tabs"), blocks, briquets, etc. In a specific embodiment, they are tableted washing or cleaning compositions.

Examples

The invention is illustrated in detail by the examples described hereinafter. The examples serve to illustrate some aspects of the present invention and should not be regarded as a restricting the present invention.

Resistance of the casein-based films against liquid detergent concentrates may be determined by “flipped vial” method (commercial detergent, ambient conditions, first droplet of liquid detergent on filter paper indicates end of shelf life). The longer it takes until films break or leak the better the barrier and resistance against liquid detergent.

Another method to demonstrate the improved barrier properties of the novel multilayer film is to use the film as a sealing material for a vial which contains a concentrated liquid detergent taken from the market (e.g. Persil duo caps). The vial is turned upside down and time is taken until first droplet of liquid detergent leaks out respectively until the vial is completely empty.

In case of casein based film the vial was empty after two respectively five days already whereas the multilayer films composed of casein film laminated either with PVOH film, gelatin film or pectin film showed good to excellent resistance against liquid detergents.

Production of Application Solution

Application Solution A

12,5 g of a solid gelatin (gelatin from porcine skin, Bloom 180, from Sigma Aldrich) were added to a stirred solution of 12,5 g glycerol in 75 g deionized water. Before heating up the mixture to 60°C the gelatin was allowed to swell for 15 minutes. The mixture was stirred at 60°C until the gelatin dissolved completely. The gelatin solution was kept at 60°C until the air stirred in had escaped completely.

Application Solution B

5 g of a powdered pectin (Pectin from apple, from Sigma Aldrich) were added to a stirred solution of 20 g glycerol in 75 g deionized water. Before heating up the mixture to 60°C the pectin was allowed to swell for 15 minutes. The mixture was stirred at 60°C until the pectin dissolved completely. The pectin solution was kept at 60°C until the air stirred in had escaped completely.

Application Solution C

13.6 g of a solid polyvinyl alcohol (Poval® 26-88 from Kuraray, nonvolatile components: 97.5%) were dissolved in 85 g of deionized water at 60°C while stirring. 1.4 g of glycerol were added to the polyvinyl alcohol solution thus prepared. The well mixed solution was then heated to 80°C for 30 minutes. The solution was cooled down to 60°C and kept at this temperature until the air stirred in had escaped completely.

Casein-based film

A casein-based film, available from BASF, was used in the experiments. The film contains at least 60% by weight casein and/or caseinate, 4 to 13% by weight water, 12 to 32% by weight of glycerol, and further additives up to 100% (percentages each relative to the total weight of the film).

Film Preparation

2-layer-film A: 1^st layer composed of gelatin, 2^nd layer composed of casein

For production of the bi-layer film, an automatic film applicator and a universal applicator from Zehntner was used. The application solution A heated to 50 °C was applied to the surface of a PET carrier. The gap width of the coating bar was chosen such that the gelatin layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 10 pm. Drying time was adjusted such that the layer still had a slightly tacky surface. Casein film of a thickness of 35 pm was applied to the tacky surface, forming a laminate of the two films with a thickness of 45 pm.

2-layer-film B: 1^st layer composed of pectin, 2^nd layer composed of casein

For production of the bi-layer film, an automatic film applicator and a universal applicator from Zehntner was used. The application solution B heated to 50°C was applied to the surface of a PET carrier. The gap width of the coating bar was chosen such that the pectin layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 10 pm. Drying time was adjusted such that the layer still had a slightly tacky surface. Casein film of a thickness of 35 pm was applied to the tacky surface, forming a laminate of the two films with a thickness of 45 pm.

2-layer-film C: 1^st layer composed of polyvinyl alcohol, 2^nd layer composed of casein

For production of the bi-layer film, an automatic film applicator and a universal applicator from Zehntner was used. The application solution C heated to 50°C was applied to the surface of a PET carrier. The gap width of the coating bar was chosen such that the polyvinyl alcohol layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 10 pm. Drying time was adjusted such that the layer still had a slightly tacky surface. Casein film of a thickness of 35 pm was applied to the tacky surface, forming a laminate of the two films with a thickness of 45 pm.

3-layer-film D: 1^st layer composed of polyvinyl alcohol, 2^nd layer composed of gelatin, 3^rd layer composed of casein

For production of the 3-layer film, an automatic film applicator and a universal applicator from Zehntner was used. The application solution C heated to 50°C was applied to the surface of a PET carrier. The gap width of the coating bar was chosen such that the polyvinyl alcohol layer, after drying at room temperature had a thickness of 6 pm. Then application solution A heated to 50°C was applied to the surface of the dried polyvinyl alcohol layer. The gap width of the coating bar was chosen such that the 2^nd layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 5 pm. Drying time was adjusted such that the 2^nd layer still had a slightly tacky surface. Casein film of a thickness of 35 pm was applied to the tacky surface, forming a laminate of the three layers with a thickness of 46 pm. 3-layer-film E: 1^st layer composed of polyvinylalcohol, 2^nd layer lamination adhesive, 3^rd layer composed of casein

For production of the 3-layer film, an automatic film applicator and a universal applicator from Zehntner was used. The application solution C heated to 50°C was applied to the surface of a PET carrier. The gap width of the coating bar was chosen such that the polyvinyl alcohol layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 6 pm. The compostable lamination adhesive (water based adhesive dispersion Epotal® Eco 3675 X, available from BASF) was applied to the surface of the dried polyvinyl alcohol layer. The gap width of the coating bar was chosen such that the 2^nd layer, after drying at room temperature and 45 to 55 % relative humidity had a thickness of 4 pm. Casein film of a thickness of 35 pm was applied to the tacky adhesive surface, forming a laminate of the three layers with a thickness of 45 pm.

Thickness measurement

Film thicknesses were determined by means of a digital gauge (Mitutoyo Absolute Digimatic gauge, ID-H model) with a flat, circular stylus of diameter 5 mm. The thickness was measured over an average of at least 10 measurement positions per film. The layer thickness variations are within a range of ±10%.

Stability test

Resistance of the casein-based films against liquid detergent concentrates was determined by using the film as a sealing material for a vial which contains a concentrated liquid detergent (formulation A resp. B). The vial is turned upside down and time is taken until the film is a) getting soft and swollen b) in addition becomes wet and smeary and c) first droplet of liquid detergent leaks out.

Table 1 : Detergent composition

Anionic Surfactant AES: Ci₂Ci₄ -Fatty alcohol ether sulfate (2EO), commercially available from BASF

Anionic Surfactant DBS: Linear Ci₀Ci₃-Alkyl Benzene Sulfonates, commercially available from BASF

Nonionic Surfactant AEO: Ethoxylated Ci₃Ci₅-oxo alcohol (7EO), commercially available from BASF

Edenor^® K12-18: Coco fatty acid, commercially available from Henkel Conditions: 22 °C, 45-50 % relative humidity vial: diameter 4 cm, height 8,5 cm, filled with 20 ml of detergent A or B multi-layer film: protective layer (barrier layer) in contact with the liquid, casein layer (outside layer) in contact with the air

The results of the stability tests are shown in Tables 2 and 3 and exemplified in the appended Figures. Table 2: Results of Stability tests with Detergent A

Table 3: Results of Stability Tests with Detergent B

* Casein films with a greater thickness, for example 80 pm, 100 pm or even 120 pm may also be used in this invention.

The experimental examples show the advantages of the inventive multilayer film, in comparison to casein-based films alone.

Claims

1. A multilayer film comprising at least one film layer L1 , comprising at least 40% by weight casein and/or caseinate, relative to the total weight of film layer L1 , and at least one film layer L2, wherein film layer L2 contains less than 10% by weight casein and/or caseinate, relative to the total weight of film layer L2, wherein film layer L2 is water-soluble.

2. A multilayer film according to claim 1 , wherein film layer L2 contains less than 5% by weight casein and/or caseinate, preferably does not contain any casein or caseinate.

3. A multilayer film according to any one of claims 1 to 2, wherein film layer L2 comprises or consists of at least one material selected from polyvinylalcohol, gelatin, pectin or mixtures thereof.

4. A multilayer film according to any one of claims 1 to 3, wherein film layer L1 comprises at least 50% by weight, preferably at least 60% by weight casein and/or caseinate, relative to the total weight of film layer L1.

5. A multilayer film according to any one of claims 1 to 4, wherein film layer 1 comprises or consists of (i) 50 to 80 weight-% casein and/or caseinate, (ii) 4 to 13 weight- % water, (iii)

10 to 35 weight-% plasticizer, (iv) 0.1 to 8 weight-% hydrophobic agent, and optionally (v) 0.5 to 6% surfactant.

6. A multilayer film according to any one of claims 1 to 5, wherein layer L1 and/or layer L2 further comprise, separately from each other, at least one additive selected from nonionic, anionic, cationic and amphoteric surfactants, builders, complexing agents, bleaches, enzymes, enzyme stabilizers, bases, corrosion inhibitors, defoamers and foam inhibitors, wetting agents, dyes, pigments, fragrances, fillers, tableting aids, disintegrants, thickeners, solubilizers, organic solvents, electrolytes, pH modifiers, perfume carriers, bitter substances, fluorescers, hydrotropes, antiredeposition agents, optical brighteners, graying inhibitors, antishrink agents, anticrease agents, dye transfer inhibitors, antimicrobial active ingredients, antioxidants, anti-yellowing agents, corrosion inhibitors, antistats, ironing aids, hydrophobizing and impregnating agents, antiswell and antislip agents, plasticizers, scavengers, agents for modification of gas permeability and water vapor permeability, antistats, glidants, slip agents, UV absorbers and mixtures thereof.

7. A multilayer film according to any one of claims 1 to 6, wherein layer L1 has a thickness of 20 to 150 pm, preferably 30 to 120 pm, and/or wherein layer L2 has a thickness of 3 to 50 pm, preferably 5 to 30 pm, determined preferably by means of a digital gauge over an average of at least 10 measurement positions per film.

8. A multilayer film according to any one of claims 1 to 7, containing an additional layer L3 between layers L1 and L2.

9. A multilayer film according to claim 8, wherein layer L3 is selected from adhesives, preferably from adhesives based on polyurethane, casein, gelatin or mixtures thereof, more preferably adhesives based on polyurethane.

10. A multilayer film according to claim 8 or 9, wherein layer L3 has a thickness of 2 to 10 pm, preferably 3 to 8 pm, determined preferably by means of a digital gauge over an average of at least 10 measurement positions per film.

11. A process for producing a multilayer film according to any of claims 1 to 10, wherein film layers L1 and L2 are laminated together, optionally in the presence of film layer L3.

12. Use of a multilayer film according to any one of claims 1 to 10 or obtainable according to the process of claim 11 , for at least partial ensheathing of a solid, gel or liquid washing or cleaning composition.