EP3649057B1

EP3649057B1 - Water-soluble package

Info

Publication number: EP3649057B1
Application number: EP18734250.6A
Authority: EP
Inventors: Rohit Kumar; Venkata Satyanarayana Murthy Kamsu; James Milton ROSSMAN; Thomas Frank SPENADER; Richard Charles FIELDER
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV
Priority date: 2017-07-07
Filing date: 2018-07-03
Publication date: 2021-01-20
Anticipated expiration: 2038-07-03
Also published as: CN110869289B; ZA202000094B; BR112019027194A2; CN110869289A; EP3649057A1; PH12019502800A1; CL2019003817A1

Description

Field of the invention

The present invention relates to a water-soluble package, and more particularly to a water-soluble package having a foamed water-soluble substrate, which substrate includes a surfactant.

Background of the invention

Water-soluble package known in the art typically encloses a cleaning or a treatment composition, such as a dishwashing or a laundry detergent composition enclosed in a water-soluble substrate that is in the form of a film, sachet, bag and other types of container or capsule. The water-soluble package is commonly used to simplify dispersing, pouring, dissolving and dosing of the composition. A consumer can directly add the package 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. The package may also reduce mess that would be associated with dispensing a similar composition from a storage container, such as pouring a liquid laundry detergent from a bottle. The package also insulates the composition therein from contact with the user's hands. In sum, water-soluble package containing pre-measured composition provide for convenience of consumer use in a variety of applications.
The water-soluble package in the form of a package, capsule or container is generally formed by sealing a water-soluble substrate to enclose a composition within. Typically, release of the contents of such water-soluble package must be quick and the water-soluble substrate enclosing the contents must dissolve completely during use in water, and without leaving a residue.
A typical problem encountered by consumers is incomplete dissolution of the water-soluble package when added in the detergent drawer of a washing machine. This problem is especially predominant when the washing machine is utilising cold water for washing purpose. To overcome this issue, the water-soluble substrate is often thin, and designed to provide high water solubility or reactivity.
Known commercially available PVOH based thermoplastic films such as M8630 from MonoSol LLC are plasticized cold-water soluble film based on a medium molecular weight fully hydrolysed PVOH having carboxylate groups. The film has a thickness of 75 microns and a weight of about 98g/m².
Although water-soluble films that completely dissolve in cold water are known, they can be too sensitive to moisture and humidity to make package for containing consumer products such as cleaning composition or treatment compositions. High humidity or water droplets from handling of the package with wet hands can cause the water-soluble package to stick together and/or dissolve through the package and cause leakage of package contents.
To reduce the sensitivity of water-soluble film to moisture and humidity, solutions have been proposed in the past. One such solution is considered in US 2006/0165625 A1 (Verrall et al. ) which describes a water-soluble article such as films, having a coating of Na₂SO₄ solution applied to the outer surface of a PVOH pouch that exhibits increased resistance to pouch-to-pouch stickiness when exposed to small amounts of water. It also discloses a method of making the water-soluble film having a step of adding salt to the water-soluble film forming composition and then forming a film from the mixture including the water-soluble-film forming composition with sodium sulphate therein.
More recently, US8309203 B2 (The Procter & Gamble Company, 2012) describes a water-soluble substrate which have improved resistance to dissolution prior to being immersed in water by providing water-insoluble particles partially embedded in said water-soluble substrate. The water-soluble substrate has a basis weight of from 33 to 167 grams per square metres and a thickness ranging from 25 micrometres to about 125 micrometres. The water-soluble substrate may have surfactants incorporate in amounts ranging from about 0.01 wt% to about 1 wt%.
For achieving good cold-water solubility, the water-soluble substrate may have to be so thin that in addition to being sensitive to moisture and humidity the mechanical properties including those relating to process-ability and heat- sealability may also be compromised. For preparing a package from the water-soluble substrate, it is desired that the water-soluble substrate must exhibit flexibility, that is, ability to accept a crease without cracking or becoming seriously weakened, in order to be useful.
Yet another solution is proposed in US3695989B1 (1972, Robert E Albert ) which describes a foamed film and cold-water soluble package made from foamed films of polyvinyl alcohol, polyvinyl pyrrolidone or mixtures of the two for use in packages for pulverulent materials. The package containing the pulverulent material may be directly charged to the water, to enable the user to dose exact measures without contacting the content of the package. The foamed film has uniformly dispersed bubbles having an average diameter less than 1/3 of the total thickness of the film.
Thus the present inventors investigated ways of improving water-soluble package and, in particular, into providing a water-soluble package that performs adequately and gives the benefits of good cold water solubility, good process-ability and flexibility. However, the present inventors have noticed that foamed water-soluble substrate having a thickness from 30 micrometres to 250 micrometres may provide improvement in cold-water solubility but are extremely susceptible to small amounts of moisture and atmospheric humidity, it is also desired that the foamed water-soluble substrate have a good bubble stability.

Summary of the invention

It is surprisingly found that water-soluble package including a foamed water-soluble substrate which substrate has a film forming material and low levels of a surfactant preferably an anionic surfactant, still preferably an alkyl sulphate anionic surfactant which enables creating and stabilizing a foam structure in the water-soluble substrate. Presence of low levels of surfactant in the foamed structure of the water-soluble substrate provides the substrate with desirable flexibility required for preparing consumer packages. Further such substrate is also thicker than dense films at the same weight per unit area due to the presence of the stable bubbles which enables them to exhibit good process-ability while maintaining good cold-water solubility.
According to a first aspect of the present invention disclosed is a water-soluble package for holding a unit dose composition comprising a water-soluble substrate having a thickness from 30 micrometres to 250 micrometres, said substrate including a film-forming material and 0.2 to 5wt% surfactant wherein the substrate has uniformly dispersed therein gas bubbles having an average diameter less than the total thickness of the substrate.
According to a second aspect of the present invention disclosed is use of the water-soluble package of the first aspect for washing dishes, treating textiles or laundering textiles.

Detailed description of the invention

According to a first aspect of the present invention disclosed is a water-soluble package for holding a unit dose composition, the water-soluble package comprising a water-soluble substrate having a thickness from 30 micrometres to 250 micrometres, said substrate comprising:(i). a film-forming material; and,
(ii). 0.2 to 5wt% surfactant;
wherein the substrate has uniformly dispersed therein gas bubbles having an average diameter less than the total thickness of the substrate.

Water-soluble package

"Water-soluble package" means any package construction that is suitable for enclosing and/or containing a composition or material, such as a dishwashing or laundry detergent composition or fabric treatment composition. The water-soluble package can be in any packaging form, such as film packaging, capsules, bag, sachets and containers. In particular embodiments, the water-soluble package is a single dose water-soluble package.
As used herein, the term "water-soluble" not only refers to a structure that is totally water-soluble, but also includes those that are substantially water-soluble but have some material(s) in the water-soluble structure that are not water-soluble; structure which are water soluble at different temperature conditions or different pH conditions and also refers to structure which are water-dispersible or water-disintegrable.
The water-soluble package typically contains at least one compartment for containing the composition. In some embodiments, the water-soluble package includes two or more compartments. Each compartment can contain same composition or a different composition from the one in another compartment. Alternatively, each compartment may contain a different component (or mixture of components) of a composition from another compartment. For example, the water-soluble package may contain two compartments wherein each compartment is a different mixture of components together constituting a laundry cleaning composition, fabric treatment composition or dishwashing composition.
The water-soluble package includes a water-soluble substrate preferably enclosing and/or containing a composition or material. In use, the water-soluble substrate may dissolve in water to release the material or composition enclosed within the substrate. Such materials and compositions particularly include, but are not limited to, detergent compositions, such as dishwashing composition, laundry detergent composition or fabric treatment composition. The material or composition may be any of solid, granular, gel, particulate, tablet or liquid form. Preferably the material or composition is a powder, particulate, tablet or granular form.
The water-soluble package may be designed as a dimensionally stable receptacle, for example in the form of a capsule, box, or container. It is also possible and preferred to form the water-soluble package as a non-dimensionally stable container, for example as a pouch or sachet. The shape of this type of water-soluble package may be adapted to a great extent to the use conditions. Various shapes such as tubes, cushions, cylinders, bottles, or disks are suitable. The water-soluble package of the invention is conveniently in the form of a pouch, bag or sachet. Such a sachet may be formed from one or more film or sheets of the water-soluble substrate or from a tubular section of such substrate, but it is most conveniently formed from a single folded sheet or from two sheets, sealed together at the edge regions either by means of an adhesive or, preferably, by heat-sealing. A preferred form of sachet according to the invention is a rectangular one formed from a single folded sheet of the water-soluble substrate sealed on three sides, although the sachet may be of any shape or size known in the art.
Preferred methods of sealing include heat sealing, solvent welding, and solvent or wet sealing. It is preferred that only the area that is to form the seal, is treated with heat or solvent. The heat or solvent can be applied by any method, preferably on the closing material, preferably only on the areas, which are to form the seal. If solvent or wet sealing or welding is used, it may be preferred that heat is also applied. Preferred wet sealing or solvent sealing/welding methods include selectively applying solvent onto the area between the moulds, or on the closing material, by for example, spraying or printing this onto these areas, and then applying pressure onto these areas, to form the seal.
The formed pouches can then be cut by a cutting device. Cutting can be done using any known method. It may be preferred that the cutting is also done in continuous manner, and preferably with constant speed and preferably while in horizontal position. The cutting device can, for example, be a sharp item or a hot item, whereby in the latter case, the hot item 'burns' through the film/sealing area.

Water-soluble substrate

Disclosed water-soluble package includes a water-soluble substrate which substrate typically forms a wall or walls of the water-soluble package for enclosing a composition.
The water-soluble substrate can be in the form of a foamed film or a foamed sheet. The water- soluble substrate may be in the form of woven, non-woven or cast structures. Preferably the water-soluble substrate is thermoplastic.
The water-soluble substrate has a thickness ranging from 30 micrometres to 250 micrometres. Preferably the thickness of the water-soluble substrate is at least 50 micrometres, still preferably at least 60 micrometres, further preferably at least 65 micrometres and most preferably at least 75 micrometres, but typically not more than 180 micrometres, still preferably not more than 170 micrometres and most preferably not more than 150 micrometres. Preferred water-soluble substrate has a thickness ranging from 75 micrometres to 150 micrometres.
Preferably, the water-soluble substrate has a basis weight in the range from 30 grams per square metre to 70 grams per square metre, more preferably the basis weight in the range from 35 grams per square metre to 50 grams per square metre. Preferably the basis weight of the water-soluble substrate is at least 32 grams per square metre, still preferably at least 34 grams per square metre, most preferably at least 35 grams per square metre, but typically not more than 60 grams per square metre, still preferably not more than 65 grams per square metre and most preferably not more than 50 grams per square metre.
The water-soluble substrate according to the present invention is a foamed structure having dispersed therein gas bubbles. In the foamed water-soluble substrate, the average diameter of the gas bubbles is less than the total thickness of the substrate. Preferably the volume of gas bubbles in the substrate is from 80% to 99% of the volume of the substrate, more preferably 85% to 95% of the volume of the substrate.

Film-forming material:

The water-soluble substrate includes a film-forming material. "Film-forming material" as used herein refers to a material that by itself or in combination with a co-reactive material, such as a crosslinking agent, is capable of forming a self-supporting continuous film on a surface upon curing and preferably includes polymeric material that upon removal of any solvents or carriers present in the polymer emulsion, dispersion, suspension or solution, can coalesce to form a film on at least a horizontal surface and is capable of curing into a continuous film. Such film-forming material preferably includes a polymer or monomer capable of producing a polymer material that exhibits properties suitable for making a film or a sheet, or a foam, such as by casting, blow-moulding, extrusion or blown extrusion of the material, as is well known in the art.
Preferred film-forming material are polymeric material, preferably polymers which are capable of being formed into a foamed film or a foamed sheet. The polymeric material can, for example, be formed into a film or sheet by casting, blow-moulding, extrusion or blown extrusion of the polymeric material, as known in the art.
Suitable film-forming material are known and includes any water-soluble polymer or mixtures of polymers. In particular, the water-soluble substrate may include one or more film-forming materials. Examples of film-forming material includes polymers, copolymers or derivatives thereof and are selected from polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl acetate, polycarboxylic acids and salts, polyacrylates, water-soluble acrylate copolymers, polyamino acids or peptides, polyamides, polylactic acid, polyaminopropyl sulfonic acid and salts thereof, polyitaconic acid and salts thereof, polyacrylamides, polyalkylene oxides, polyvinylpyrrolidone, pullalan, cellulosics (cellulose, cellulose ethers, cellulose esters, cellulose amides and includes examples such as carboxy methylcellulose and hydroxypropyl methylcellulose), water-soluble natural polymers (such as guar gum, xanthan gum, carrageenan and starch), water-soluble polymer derivatives (such as modified starches, including ethoxylated starch and hydroxylated propylstarch, poly(sodium acryloamido-2-methylpropane sulfonate, polymonomethylmaleate and salts thereof) and combinations thereof.
More preferred polymers are selected from polyacrylates and water-soluble acrylate copolymers, methylcellulose, carboxy methylcellulose sodium, dextrin, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose, maltodextrin, polymethacrylates. Most preferably the film-forming material includes polyvinyl alcohol, polyvinyl alcohol copolymers, partially hydrolysed polyvinyl acetate, modified polyvinyl alcohol preferably modified with a carboxyl group, vinylamide monomer and/or a sulfonic acid group or other functional groups known in the art to improve the solubility in water, polyvinyl acetate, polyvinyl pyrrolidone, carboxy methylcellulose or hydroxypropyl methyl cellulose.
Still preferably, the film-forming material includes or consists essentially of vinyl polymers, including homo-polymers and copolymers having hydroxyl or carboxyl groups. Preferred polymers include polyvinyl alcohol, polyvinyl acetate, partially hydrolysed polyvinyl acetate, modified polyvinyl alcohol or mixtures thereof. Polyvinyl alcohol, polyvinyl acetate and modified polyvinyl alcohols can provide stable water-soluble substrate that have suitable dissolution rates. Preferably the film-forming material in the water-soluble substrate is a PVOH.
Mixtures of polymers can also be used as the film-forming material. This can be beneficial to control the mechanical and/or dissolution properties of the package, depending on the application thereof and the required needs. Suitable mixtures include for example mixtures wherein one polymer has a higher water-solubility than another polymer, and/or one polymer has a higher mechanical strength than another polymer. Also suitable are mixtures of polymers having different weight average molecular weights, for example a mixture of polyvinyl alcohol or a copolymer thereof of a weight average molecular weight of about 10,000 to 40,000, preferably around 20,000, and of poly vinyl alcohol or copolymer thereof, with a weight average molecular weight of about 100,000 to 300,000, preferably around 150,000.
Preferably the film forming material is a polymer having a weight average molecular weight of from 1000 to 1x10⁶, preferably from 1x10⁴ to 3x10⁵, yet preferably from 20,000 to 1.5X10⁵.
Preferably, the level of film forming material in the water-soluble substrate, for example a polyvinyl alcohol polymer, is at least 40 wt%, still preferably at least 50 wt%, further preferably at least 55 wt% and most preferably at least 65 wt%, but typically not more than 85wt%, still preferably not more than 80 wt% and most preferably not more than 75 wt%.
The film-forming material is preferably a polymer that is hydrolyzed. To provide the desired film properties for preparing a package while maintaining acceptable dissolution rates it is preferred that the polymer is partially hydrolysed, more preferably the polymer has a degree of hydrolysis ranging from 60% to 99%, preferably 60% to 98%, still preferably in the range from 60% to 90%, further preferably in the range from 65% to 85% and most preferably from 75% to 85%. Most preferably the degree of hydrolysis is between 75% to 80%. Preferably the film-forming material is a hydrolysed polyvinyl acetate preferably having a degree of hydrolysis from 60% to 90%.
Preferably, the process for preparing a water-soluble substrate from a film-forming material involves a step of blowing or casting the film-forming material or a solution thereof, preferably the water-soluble substrate is produced by a casting process.

Surfactant:

Disclosed water-soluble substrate includes 0.2 to 5wt% surfactant. The desired level of surfactant according to the present invention in the water-soluble substrate provides stability to the dispersed gas bubbles in the foamed water-soluble substrate and improves the flexibility and heat seal-ability of the substrate enabling the substrate to be advantageously used for preparing a package for holding a composition or material which must be released.
Preferably the amount of surfactant in the water-soluble substrate is at least 0.25 wt%, still preferably at least 0.3wt%, further preferably at least 0.4wt% and most preferably at least 0.45wt%, but typically not more than 4wt%, still preferably not more than 3.5 wt%, further preferably not more than 3wt% and most preferably not more than 2 wt%.
Suitable surfactants may include the anionic, nonionic, cationic, amphoteric and zwitterionic classes or mixtures thereof. Suitable surfactants include, but are not limited to, polyoxyethylenated polyoxypropylene glycols, alcohol ethoxylates, alkylphenol ethoxylates, tertiary acetylenic glycols and alkanolamides (nonionics), polyoxyethylenated amines, quaternary ammonium salts and quaternized polyoxyethylenated amines (cationics), and amine oxides, N-alkylbetaines and sulfobetaines (zwitterionics).
Preferably the surfactant is an anionic surfactant selected from straight chain or branched alkyl sulfates, sulfonate surfactant, alkyl polyalkoxylated sulfates, also known as alkyl ether sulfates such surfactants may be produced by the sulfation of higher Cs-C₂₀ fatty alcohols or mixtures thereof.
Examples of primary alkyl sulfate surfactants are those of formula:

ROSO₃ ^-M⁺

wherein R is a linear C₈-C₂₀ hydrocarbyl group and M is a water-solubilising cation.
Preferably R is C₁₀-C₁₆ alkyl, for example C₁₂-C₁₄, and M is an alkali metal such as lithium, sodium or potassium.
Examples of secondary alkyl sulfate surfactants are those which have the sulfate moiety on a "backbone" of the molecule, for example those of formula: CH₂(CH₂)_n(CHOSO₃ ^-M⁺)(CH₂)_mCH₃ wherein m and n are independently 2 or more, the sum of m+n typically being 6 to 20, for example 9 to 15, and M is a water-solubilising cation such as lithium, sodium or potassium.
Especially preferred secondary alkyl sulfates are the (2,3) alkyl sulfate surfactants of formulae:

CH₂(CH₂)_x(CHOSO₃ ^-M+)CH₃ and CH₃(CH₂)_x(CHOSO₃ ^-M⁺)CH₂CH₃

for the 2-sulfate and 3-sulfate, respectively. In these formulae x is at least 4, for example 6 to 20, preferably 10 to 16. M is cation, such as an alkali metal, for example lithium, sodium or potassium.
Examples of alkoxylated alkyl sulfates are ethoxylated alkyl sulfates of the formula: RO(C₂H₄O)_nSO₃ ^-M⁺ wherein R is a C₈-C₂₀ alkyl group, preferably C₁₀-C₁₈ such as a C₁₂-C₁₆, n is at least 1, for example from 1 to 20, preferably 1 to 15, especially 1 to 6, and M is a salt-forming cation such as lithium, sodium, potassium, ammonium, alkylammonium or alkanolammonium. These compounds can provide especially desirable fabric cleaning performance benefits when used in combination with alkyl sulfates.
The alkyl sulfates and alkyl ether sulfates will generally be used in the form of mixtures comprising varying alkyl chain lengths and, if present, varying degrees of alkoxylation.
Other anionic surfactants which may be employed are salts of fatty acids, for example C₈-C₁₈ fatty acids, especially the sodium or potassium salts, and alkyl, for example C₈-C₁₈, benzene sulfonates.
Most preferably, the anionic surfactant is a sulphated anionic surfactant, preferably the alkali metal salt of lauryl sulphate, still preferably sodium lauryl sulphate. The sulphated anionic surfactant preferably the sodium lauryl sulphate is included in the foamed water-soluble substrate at a level ranging from 0.2% to 5%, more preferably from 0.25% to 2%, still preferably from 0.4% to 1% by weight of the water-soluble substrate.
Examples of non-ionic surfactants are fatty acid alkoxylates, such as fatty acid ethoxylates, especially those of formula:

R(C₂H₄O)_nOH

wherein R is a straight or branched C₈-C₁₆ alkyl group, preferably a C₉-C₁₅, for example C₁₀-C₁₄, alkyl group and n is at least 1, for example from 1 to 16, preferably 2 to 12, more preferably 3 to 10.
The alkoxylated fatty alcohol non-ionic surfactant will frequently have a hydrophilic-lipophilic balance (HLB) which ranges from 3 to 17, more preferably from 6 to 15, most preferably from 10 to 15.
Examples of fatty alcohol ethoxylates are those made from alcohols of 12 to 15 carbon atoms and which contain about 7 moles of ethylene oxide. Such materials are commercially marketed under the trademarks Neodol 25-7 and Neodol 23-6.5 by Shell Chemical Company. Other useful Neodols include Neodol 1-5, an ethoxylated fatty alcohol averaging 11 carbon atoms in its alkyl chain with about 5 moles of ethylene oxide; Neodol 23-9, an ethoxylated primary C₁₂-C₁₃ alcohol having about 9 moles of ethylene oxide; and Neodol 91-10, an ethoxylated C₉-C₁₁ primary alcohol having about 10 moles of ethylene oxide.
Alcohol ethoxylates of this type have also been marketed by Shell Chemical Company under the Dobanol trademark. Dobanol 91-5 is an ethoxylated C₉-C₁₁ fatty alcohol with an average of 5 moles ethylene oxide and Dobanol 25-7 is an ethoxylated C₁₂-C₁₅ fatty alcohol with an average of 7 moles of ethylene oxide per mole of fatty alcohol.
Other examples of suitable ethoxylated alcohol non-ionic surfactants include Tergitol 15-S-7 and Tergitol 15-S-9, both of which are linear secondary alcohol ethoxylates available from Union Carbide Corporation. Tergitol 15-S-7 is a mixed ethoxylated product of a C₁₁-C₁₅ linear secondary alkanol with 7 moles of ethylene oxide and Tergitol 15-S-9 is the same but with 9 moles of ethylene oxide.
Other suitable alcohol ethoxylated non-ionic surfactants are Neodol 45-11, which is a ethylene oxide condensation products of a fatty alcohol having 14-15 carbon atoms and the number of ethylene oxide groups per mole being about 11. Such products are also available from Shell Chemical Company.
Further non-ionic surfactants are, for example, C₁₀-C₁₈ alkyl polyglycosides, such as C₁₂-C₁₆ alkyl polyglycosides, especially the polyglucosides. These are especially useful when high foaming compositions are desired. Further surfactants are polyhydroxy fatty acid amides, such as C₁₀-C₁₈ N-(3-methoxypropyl) glycamides and ethylene oxide-propylene oxide block polymers of the Pluronic type.
Examples of cationic surfactants are those of the quaternary ammonium type.

Plasticizer:

Preferably the water-soluble substrate includes a plasticizer. Examples of preferred plasticizer includes, but is not limited to glycerol, glycerin, diglycerin, hydroxypropyl glycerine, sorbitol, methylene glycol diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycols, neopentyl glycol, trimethylolpropame, polyether polyols, ethanolamines, and mixtures thereof. The plasticizer, when present, may be included in the water-soluble substrate material in an appropriate amount, as generally known. Preferably, the plasticizer is a combination of glycerin and polyethylene glycol.

Method for preparing the water-soluble package

The water-soluble package of the present invention can be manufactured using standard known techniques. For example, the water-soluble substrate is typically formed (preferably thermoformed) into a water-soluble substrate enclosure (e.g. a film pocket, open capsule or container). The water-soluble substrate enclosure may then be filled with a composition such as a dishwashing or laundry detergent composition or fabric treatment composition. The fabric treatment composition may be a post-wash treatment composition, preferably added at the rinse stage or a pretreatment composition. The water-soluble enclosure containing the composition or material can then be sealed, for example by sealing the edges of the enclosure or joining the enclosure with one or more additional pieces of water-soluble substrate, in order to enclose the material or composition in the water-soluble package. The water-soluble package holding the composition may be in the form of a single- and multiple-compartment pouch, sachets, bags etc.
Water-soluble package and other such containers that incorporate the water-soluble substrate described herein can be made in any suitable manner known in the art. There are a number of processes for making water-soluble package. These include but are not limited to processes known in the art as: vertical form-fill-sealing processes, horizontal form-fill sealing processes, and formation of the package in molds on the surface of a circular drum.
In vertical form-fill-sealing processes, a vertical tube is formed by folding a substrate. The bottom end of the tube is sealed to form an open package. This package is partially filled allowing a head space. The top part of the open package is then subsequently sealed together to close the package, and to form the next open package. The first package is subsequently cut, and the process is repeated. The package formed in such a way usually have pillow shape.
Horizontal form-fill sealing processes uses a die having a series of molds therein. In horizontal form-fill sealing processes, a substrate is placed in the die and open package are formed in these molds, which can then be filled, covered with another layer of substrate, and sealed.
In the third process (formation of package in molds on the surface of a circular drum), a substrate is circulated over the drum and pockets are formed, which pass under a filling machine to fill the open pockets. The filling and sealing takes place at the highest point (top) of the circle described by the drum, e.g. typically, filling is done just before the rotating drum starts the downwards circular motion and sealing just after the drum starts its downwards motion.
In any of the processes that involve a step of forming of open package, the water-soluble substrate can initially be molded or formed into the shape of an open package using thermoforming, vacuum-forming, or both. Thermoforming involves heating the molds and/or the substrate by applying heat in any known way such as contacting the molds with a heating element, or by blowing hot air or using heating lamps to heat the molds and/or the substrate. In the case of vacuum-forming, vacuum assistance is employed to help drive the substrate into the mold. In other embodiments, the two techniques can be combined to form package, for example, the substrate can be formed into open package by vacuum-forming, and heat can be provided to facilitate the process. The open package is then filled with the composition to be contained therein.
The filled, open package are then closed, which can be done by any method. In some cases, such as in horizontal package -forming processes, the closing is done by continuously feeding a second material or substrate, such as a water-soluble substrate, over and onto the web of open pouches and then sealing the first substrate and second substrate together. In such a process, the first and second substrates are typically sealed in the area between the molds, and, thus, between the package that are being formed in adjacent molds. The sealing can be done by any method. Methods of sealing include heat sealing, solvent welding, and solvent or wet sealing. The sealed webs of package can then be cut by a cutting device, which cuts the package in the web from one another, into separate package.

Method of use

The water-soluble package of the present invention comprises a composition which composition may be a fabric treatment composition or a fabric cleaning composition that may be utilized in a method for treating a fabric article. Depending on the composition contained in the water-soluble package the method of treating a fabric article with the water-soluble package may comprise one or more steps selected from the group consisting of: (a) pre-treating the fabric article in a liquor formed by contacting the water-soluble package enclosing a pretreatment composition with water before washing the fabric article; (b) laundering the fabric article with a wash liquor formed by contacting the water soluble package enclosing a cleaning composition with water; (c) contacting the fabric article with the water soluble package enclosing a post-wash treatment composition after the laundering process; and (d) combinations thereof.
In some embodiments, the method may comprise the step of selecting of only a portion of the water-soluble package for use in treating a fabric article. The desired portion or compartment of the water-soluble package may be cut and/or torn away and either placed on or adhered to the fabric or placed into water to form a relatively small amount of wash liquor which is then used to pre-treat or give a post laundering treatment to the fabric. In this way, the user may customize the fabric treatment method according to the task at hand. In some embodiments, at least a portion of a water-soluble package may be applied to the fabric to be treated using a device like a brush or a sponge. In yet another embodiment, the water-soluble package may be applied directly to the surface of the fabric. Any one or more of the aforementioned steps may be repeated to achieve the desired fabric treatment benefit.

Optional ingredients:

Disintegrants:

To improve the dissolution rate of the substrate disintegrants are preferably applied on the surface of the water-soluble substrate or they may be applied integrated into the water-soluble substrate or any combination thereof, in order to speed up the dissolution when the water-soluble substrate is immersed in water. Where present, the level of disintegrant is from 0.1 to 30%, preferably from 1 to 15%, by weight of said water-soluble substrate. Any suitable disintegrant known in the art may be used. Preferred disintegrants for use herein include corn/potato starch, methyl cellulose/celluloses, mineral clay powders, cross-linked cellulose, cross-linked polymer, cross-linked starch.

Release agents:

Suitable release agents include, but are not limited to, fatty acids and their salts, fatty alcohols, fatty esters, fatty amines, fatty amine acetates and fatty amides. The release agent can be incorporated in the water-soluble substrate in any suitable amount including amounts within the range of from about 0.02% to about 1.5% by weight, or in the range of from about 0.04% to about 0.15% by weight.
Further optional ingredients may also include suitable extenders, anti-blocking agents, detackifying agents include, but are not limited to: starches, modified starches, crosslinked polyvinylpyrrolidone, crosslinked cellulose, microcrystalline cellulose, and metallic oxides. The extender, antiblocking agent, detackifying agent can be present in the water-soluble substrate in any suitable amount including amounts in the range of from about 0.1% to about 25% by weight, preferably in the range of from about 1% to about 15% by weight.

Composition enclosed or contained in the water-soluble package

The composition in the water-soluble package may be any composition that is intended to be directly dosed preferably into a washing machine when the package dissolves or disintegrates. The composition may, for example, be a fabric treatment or fabric laundering, surface care or dishwashing composition. Thus, for example, it may be a dishwashing, water-softening composition, laundry or detergent composition, a rinse-treatment composition, fabric-conditioning composition or pretreatment composition. The composition may be in any form and not limited to powder, granular, tablet, particulate or a combination thereof.
Suitable composition is generally packaged in amounts of from 0.5 to 100g, preferably from 5 to 100g, especially from 15 to 40g. For example, a laundry composition may weight from 0.5 to 40 g preferably from 15 to 40g. Most preferably the amount of composition enables the user to unit dose the composition for each wash cycle of the washing machine or for pre-treatment or rinse-treatment of the textile.
The invention will be described in more detail with reference to specific embodiments and examples.

Examples

Example 1: Water-soluble substrate having polyvinyl alcohol and surfactant

A water-soluble substrate according to the present invention was prepared by mixing the ingredients as disclosed in the Table 1 below in a silverson mixer and also nitrogen gas was purged to introduce gas bubbles. In the next step, the mixture obtained was cast on a casting belt having a wet film thickness of around 380 microns to 750 microns, thereafter the cast mixture was dried in an oven to provide a film reel which had a final thickness of around 75 micrometer to 200 micrometres.

Table 1

Composition of the water-soluble substrate
Ingredients	Concentration (wt%)
Partially hydrolysed polyvinyl alcohol	64
Polyethylene glycol	3.8
glycerine	2.2
Sodium lauryl sulphate	0.45
Other ingredients	10
Balance	100

The water-soluble substrate having the composition provided in table 1 that includes a surfactant (sodium lauryl sulphate) within the claimed ranges was found to have stable gas bubbles dispersed in the structure and was also soluble in cold water at a temperature of 10°C.

Example 2: Evaluation of water-soluble substrate having different types of surfactant and without surfactant.

A comparative water-soluble substrate (Ex A) was prepared by mixing the ingredients as disclosed in the Table 2 below in a silverson mixer along with incorporation of air with vigorous mixing to obtain a solution with a density of 0.67 grams/mL. In the next step the mixture obtained was cast on a casting belt having a wet film thickness of 380 micrometres, thereafter the cast mixture was dried in an oven to provide a film reel. The water-soluble substrate obtained had a moisture content was 3.1wt%.
A water-soluble substrate (Ex 2) according to the present invention was prepared by mixing the ingredients as disclosed in the Table 2 below in a silverson mixer and the solution obtained had a solution density of 0.69 grams/mL. In the next step the mixture obtained was cast on a casting belt having a wet film thickness of 380 micrometres, thereafter the cast mixture was dried in an oven to provide a film reel. The water-soluble substrate obtained had a moisture content was 2.5wt%.

The composition of the prepared water-soluble substrate as described above are given in Table 2. The two water-soluble substrates were evaluated for heat seal-ability and the film strength, solubility in water and the details are provided in the Table 2.

Table 2

Ingredients	Ex A (wt%)	Ex 2 (wt%)
Partially hydrolysed polyvinyl alcohol	69.3	76.5
Polyethylene glycol (PEG-600)	3.8	3.8
Glycerin	2.2	2.2
Anionic surfactant (SLES 3EO)	0	3.8
Microcrystalline cellulose (MCC)	24.7	13.7
Film strength	Poor	Fair
Heal seal @ 150°C	Low, seal tears at seal line. Film brittle and crumbles	Good, film seals and does not crumble.
Solubility in cold water @ 5°C	Completely dissolved in 270 seconds	Completely dissolved in 131 seconds
Bubble stability	Bubble collapsed immediately after agitation was stopped	Bubble was stable even after agitation stopped

*Steol ®CS-370 from Stephan Company

The data in Table 2 shows that a comparative water-soluble substrate (Ex A) in which the air was incorporated by vigorous mixing, the bubble structure began collapsing immediately after the agitation was stopped as compared to the water-soluble substrate according to the present invention (Ex 1) where the bubble remained stable for longer. The comparative water-soluble substrate (Ex A) was inferior in seal strength and film strength and took longer to dissolve completely in water @5°C when compared to the water-soluble substrate according to the present invention.

Claims

A water-soluble package for holding a unit dose composition, the water-soluble package comprising a water-soluble substrate having a thickness from 30 micrometres to 250 micrometres, said substrate comprising:
(i). a film-forming material; and,

(ii). 0.2 to 5wt% surfactant;
wherein the substrate has uniformly dispersed therein gas bubbles having an average diameter less than the total thickness of the substrate.
A package according to claim 1 wherein the gas bubbles has a total volume of from 80 to 99% of the total volume of the substrate.
A package according to claim 1 or 2 wherein the surfactant is an anionic or non-ionic surfactant.
A package according to claim 3 wherein the anionic surfactant is a sulphate surfactant.
A package according to claim 4 wherein the sulphated anionic surfactant is sodium lauryl sulphate.
A package according to any preceding claims wherein the film-forming material is a polymer selected from polyvinyl alcohol, polyvinyl acetate, modified polyvinyl alcohol, carboxy methylcellulose, hydroxypropyl methylcellulose or mixtures thereof.
A package according to claim 6 wherein the polymer has a weight average molecular weight of at least 1X10⁵.
A package according to claim 6 or 7 wherein the polymer is partially hydrolysed having a degree of hydrolysis ranging from 60% to 99%.
A package according to any one of the preceding claims wherein the water-soluble substrate comprises a plasticizer selected from the group consisting of glycerol, glycerin, diglycerin, hydroxypropyl glycerine, sorbitol, methylene glycol diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycols, neopentyl glycol, trimethylolpropame, polyether polyols, ethanolamines, and mixtures thereof.
A package according to any one of the preceding claims wherein the water-soluble substrate has a basis weight in the range from 35 grams per square metre to 50 grams per square metre.
A package according to any one of the preceding claims wherein the amount of film- forming material is from 55 to 80% by weight of the water-soluble substrate.
A package according to any one of the preceding claims wherein the water-soluble substrate has a thickness from 75 micrometers to 150 micrometers.
A package according to any one of the preceding claims wherein the water-soluble substrate encloses a composition or material that is a powder, particulate tablet or granular form.
A package as claimed in claim 13 wherein the composition is a dishwashing composition, fabric treatment composition, or a laundry detergent composition.
Use of a water-soluble package according to any one of the preceding claims for washing dishes or laundering textiles.