The present invention relates to a water-soluble capsule comprising a water- soluble film, and methods for forming it. Background of the Invention

Detergent compositions for the machine washing of laundry are provided in many forms, including free-flowing powders and liquids. Detergents in the form of compressed powder tablets are also commonly available. These are advantageous because they are easier to handle and dispense into the wash load. They also allow for accurate dosing of detergent.

More recently water-soluble capsules of detergent composition in liquid and other forms have been introduced. Water-soluble capsules generally comprise a detergent composition encapsulated within water-soluble film, such as polyvinyl alcohol. Encapsulation allows for handling of the product without direct contact with the detergent composition. This is especially advantageous when the detergent composition includes aggressive cleaning components which would irritate the skin on direct contact, such as enzymes and bleaching agents.

Liquid detergents also offer potential aesthetic benefits in so far as they can be coloured e.g. to denote a particular function or fragrance. However, a problem encountered with coloured liquids is that fairly high levels of colourant are needed which can be costly, and can lead to staining of the fabrics to be washed.

Furthermore, colouring of the fluid can be problematic in so far as the colouring agent, e.g. dye or pigment used can be unstable in the liquid. A further problem is that the capsule film can be visually unappealing to some consumers. This can be overcome by adding traditional colorants such as dyes and pigments to the film, as detailed in EP1405800A1.

It is an object of the present invention to provide a water-soluble capsule containing a composition, which overcomes at least some of the above mentioned problems. In particular, it is an object of the invention to provide a water-soluble capsule with improved visual properties and a reduction in colourant-related staining problems. It has been found that coloured capsules can be made by incorporating into them energy activated colour change agents. Summary of the Invention

A first aspect of the invention is a water-soluble capsule comprising a water- soluble film encapsulating a composition, wherein the film comprises a colour former which is susceptible to changing colour when irradiated.

A second aspect of the invention is a method of imparting colour to a water- soluble capsule according to the first aspect of the invention, wherein at least part of the film is irradiated to change its colour. A final aspect of the invention is a coloured water-soluble capsule, obtainable by the method according to the second aspect of this invention. Description of the Invention

The energy activated colour formers suitable for use in the present invention include diacetylenes, charge transfer agents, leuco dyes, photochromies, molybdates, dehydration agents and the like. Suitable examples of these chemistries are taught in WO2006129086 A1 , WO2007045912 A1 , WO2002068205 A1 , WO2006129078 A1 , WO2004043704 A1 , WO2002074548 A3, WO2006018640 A1 , WO2007063339 A3 and WO2006051309 A1.

Particularly preferred are diacetylenes, charge transfer agents and leuco dyes. Charge transfer agents and leuco dyes are particularly preferred when used in combination with a photoacid generating agent. The most preferred colour formers are diacetylenes. Preferred colour formers are those that are colourless un-activated but become visually coloured on activation.

Any diacetylene or combination of diacetylene and other substances capable of undergoing a colour change reaction upon exposure to light may be used in the present invention.

Diacetylene compounds are substances which include at least one diacetylene group, i.e. -C≡C-C≡C-. Particularly preferred are diacetylene compounds that exhibit a polychromic colour change reaction. These compounds are initially colourless but on exposure to suitable light, such as a ultra-violet light, undergo a colour change reaction to produce a blue colour. Certain diacetylenes in their blue form can then be exposed to further light such as near-infrared light, which converts the blue form into a magenta, red, yellow and green form. Specific examples of diacetylene compounds may be used in the present invention are given in the published patent application number WO2006/018640.

Further examples include those represented by the following general structures: or,

or,

or,

wherein,

X and Y are divalent straight-chain or branched alkylene type groups (-CH ₂ - ) _n wherein n = 0 to 24, or a divalent phenylene type group (-C ₆ H ₄ -) _n wherein n = 0 to 1 or a combination of both types;

Q and V, if present, are divalent bridging groups such as -S-, -O-, -NHR'- wherein R' is hydrogen or alkyl, amide, ester or thioester groups, carbonyl or carbamate;

R1 and R2 are H or alkyl; A and T are divalent groups that can either be an alkylene or phenylene type such as X or Y, or a bridging type such as Q or V, or a combination of both types, X or Y that additionally comprises a Q or V group;

Z is a divalent group such as X or Q or a combination of both, X that additionally comprises a Q group, or Z can be not present, and n is 2 to 20,000,000.

Groups X and Y are optionally substituted, preferably at the α, β or Y position with respect to the diacetylene group. For instance, there may be an α-hydroxy group, as shown in the formula below:

The diacetylene may be symmetrical or non-symmetrical. Q and V are optionally substituted with groups such as amine, alcohol, thiol or carboxylic acid. Both Q and V may be present, or alternatively, just Q. Where R1 and R2 in the above compounds are alkyl, they may be straight or branched chain and may additionally comprise other functional groups known in organic chemistry such as alcohol, amine, carboxylic acid, aromatic ring systems and unsaturated groups such as alkenes and alkynes.

Groups R1 , R2, Q, V, X and Y may comprise ionic groups, which can be anionic or cationic. Examples include sulphate groups (-SO ₃ -) and ammonium groups. The ionic groups can have any suitable counterion.

Further diacetylene compound examples are diacetylene carboxylic acids and derivatives thereof. A particularly preferred diacetylene carboxylic acid compounds are 10,12-pentacosadiynoic acid and 10,12-docosadiyndioic acid and their derivatives thereof. Further examples include: 5,7,-dodecadiyndioic acid, 4,6- dodecadiynoic acid, 5,7-eicosadiynoic acid, 6,8-heneicosadiynoic acid, 8,10- heneicosadiynoic acid, 10,12-heneicosadiynoic acid, 10,12-heptacosadiynoic acid,

12,14-heptacosadiynoic acid, 2,4-heptadecadiynoic acid, 4,6-heptadecadiynoic acid, 5,7-hexadecadiynoic acid, 6,8-nonadecadiynoic acid, 5,7-octadecadiynoic acid, 10,12-octadecadiynoic acid, 12,14-pentacosadiynoic acid, 2,4- pentadecadiynoic acid, 5,7-tetradecadiynoic acid, 10,12-tricosadiynoic acid 2,4- tricosadiynoic acid, and derivatives thereof. Diacetylene alcohols and diol compounds and derivatives thereof are also preferred, examples include: 5,7- dodecadiyn-1 ,12-diol, 5,7-eicosadiyn-1 -ol, 2,4-heptadecadiyn-1 -ol, 2,4-hexadiyn- 1 ,6-diol, 3,5-octadiyn-1 ,8-diol, 4,6-decadiyn-1 ,10-diol, 2,7-dimethyl-3,5-octadiyn-2,7- diol, 14-hydroxy-10,12-tetradecadiynoic acid. Others include 1 ,6-diphenoxy-2,4- hexadiyne, 1 ,4-diphenylbutadiyne, 1 ,3-heptadiyne, 1 ,3-hexadiyne and 2,4- hexadiyne.

A combination of different diacetylenes can also be employed. A particularly preferred combination is that of 10,12-pentacosadiynoic acid or 10,12- docosadiyndioiac acid and derivatives thereof and 2,4-hexadiyn-1 ,6-diol. 10,12- pentacosadiynoic acid can produce blue, red and yellow. 2,4-hexadiyn-1 ,6-diol can produce a cyan colour. Activating 10,12-pentacosadiynoic acid to yellow and 2,4- hexadiyn-1 ,6-diol to cyan simultaneously gives rise to green. A diacetylene compound that is 'activatable', i.e. has a first solid form that is relatively unreactive to light, but upon 'activation' is transformed into a second form that is relatively reactive to light and is thus capable of undergoing a colour change reaction to create a visible image, has particular utility in the present invention. Without being limited by theory the activation could be a re-crystallisation, crystal form modification, co-crystal combination or a melting/re-solidification process.

Reversibly activatable diacetylenes that can flip between unactivated and activated forms in response to or removal of a stimulus also form part of the present invention.

Particularly preferred diacetylenes are those that after initial melting and re- solidification activation are colourless but become blue on exposure to light, particularly UV light. The most preferred diacetylenes compounds are carboxylic acids and derivatives thereof where:

R-C≡C-C≡C-R' either R and/or R' comprises a COX group, where X is: -NHY, -OY, -SY, where Y is H or any group comprising at least one carbon atom.

Particularly preferred still are derivatives in which the carboxylic acid group has been functionalised into an amide, ester or thioester. These can be easily made by reacting a diacetylene carboxylic acid with a chlorinating agent such as oxalyl chloride and then reacting the diacetylene acid chloride with a nucleophilic compound such as an amine, alcohol or thiol. A particularly preferred diacetylene carboxylic acid compound is 10,12-docosadiyndioic acid and derivatives thereof such as amides, esters, thioesters and the like. Especially particularly preferred 10,12-docosadiyndioic acid derivatives are amides. A particularly preferred still 10,12-docosadiyndioic acid amide derivative is the propargylamide in which at least one, preferably both carboxylic acid groups have been transformed into the propargylamide, as shown below:

Propargylamides are made by reacting carboxylic acids with propargylamine.

Other preferred amines that can be used to create suitable amides include: dipropargylamine and 1 ,1-dimethylpropargylamine.

The activatable diacetylene is generally used together with a NIR light absorbing agent, which is a compound that absorbs light in the wavelength range 700 to 2500 nm.

A NIR light source, such as a NIR fibre laser, is used to heat the film only in the areas where the image is required. A UV light source, such as a germicidal lamp, is then used to flood the film with UV light. However, the diacetylene compound only undergoes a colour change reaction to create an image in the areas which were initially exposed to NIR light. The areas of the film unexposed to NIR light undergo a negligible colour change reaction, remain essentially colourless, and are stable to background radiation. A thermal print head may be used to initiate the heat-based pre-activation step. Specific examples of NIR light absorbing agents include: i. Organic NIR absorbing agents ii. NIR absorbing 'conductive' polymers iii. Inorganic NIR absorbing agents iv. Non-stoichiometric inorganic absorbing agents. Particularly preferred NIR absorbing agents are those that have essentially no absorbance in the visible region of the spectrum (400 to 700 nm) and thus give rise to coatings that appear visibly colourless.

Organic NIR absorbing agents are known as NIR dyes/pigments. Examples include but are not limited to: families of metallo-porphyrins, metallo-thiolenes and polythiolenes, metallo-phthalocyanines, aza-variants of these, annellated variants of these, pyrylium salts, squaryliums, croconiums, amminiums, diimoniums, cyanines and indolenine cyanines.

Examples of organic compounds that can be used in the present invention are taught in US6911262, and are given in Developments in the Chemistry and Technology of Organic dyes, J Griffiths (ed), Oxford: Blackwell Scientific, 1984, and Infrared Absorbing Dyes, M Matsuoka (ed), New York: Plenum Press, 1990. Further examples of the NIR dyes or pigments of the present invention can be found in the EpolightTM series supplied by Epolin, Newark, NJ, USA; the ADS series supplied by American Dye Source Inc, Quebec, Canada; the SDA and SDB series supplied by HW Sands, Jupiter, FL, USA; the Lumogen™ series supplied by BASF, Germany, particularly Lumogen™ IR765 and IR788; and the Pro-Jet™ series of dyes supplied by FujiFilm Imaging Colorants, Blackley, Manchester, UK, particularly Pro-Jet™ 830NP, 900NP, 825LDI and 830LDI. Further examples are taught in WO08/050153.

Examples of NIR absorbing 'conductive' polymers include PEDOT such as, the product Baytron ^® P supplied by HC Starck. Further examples are taught in WO05/12442.

Examples of inorganic NIR absorbing agents include copper (II) salts. Copper (II) hydroxyl phosphate (CHP) is particularly preferred. Further examples are taught in WO05/068207.

Examples of non-stoichiometric inorganic absorbing agents include reduced indium tin oxide, reduced antimony tin oxide, reduced titanium nitrate and reduced zinc oxide. Further examples are taught in WO05/095516. Reduced indium tin oxide is particularly preferred in combination with a 1550 nm to 2500 nm laser. It is particularly preferred if the absorption profile of the NIR absorbing agent approximately matches the emission wavelength(s) of the NIR light source employed.

Other light absorbing agents that can be used, instead of the NIR absorbing agent include UV (120 to 400 nm), visible (400 to 700 nm) and mid-infrared (-10.6 microns) light absorbing agents. Examples includes dyes/pigments, UV absorbers and lriodin type agents.

Charge transfer agents may be used together with a diacetylene in the present invention. These are substances that are initially colourless but react with protons (H ⁺ ) to produce a coloured form. Charge transfer agents that form part of the present invention include compounds known as carbazoles and suitable examples are described in WO2006/051309. Further charge transfer agents known to those skilled in the art such as leuco dyes can also be used. Charge transfer agents are usually used in combination with other substances such as light absorbing agents which can be wavelength specific, heat generating agents, acid generating agents and the like.

A particularly preferred combination for use in this invention is a diacetylene such as 10,12-pentacosaidiynoic acid, or 10,12-docosadiyndioic acid (or a derivative thereof), to give blue and red, with a charge transfer agent that generates green.

Charge transfer agents are compounds that in the neutral state are coloured but upon acquiring a charge, usually upon protonation become form highly coloured complexes. Carbazoles are suitable charge transfer agents, particularly N-ethyl carbazole. Leuco dyes are colourants that change colour on response to a change in environment. Typically leuco dyes are colourless within an alkaline or neutral environment but become coloured within an acidic environment. Suitable leuco dyes are described in "Dyestuffs and Chemicals for Carbonless Copy Paper" presented at Coating Conference (1983, San Francisco, CA pp 157-165) by Dyestuffs and Chemicals Division of Ciba-Geigy Corp Greenboro, NC. Leuco dyes are understood to be colourless in neutral or alkaline media, but become coloured when they react with an acidic or electron accepting substance. Suitable examples include compounds such as triphenylmethanephthalide compounds, azaphthalide compounds, isoindolide phthalide compounds, vinylphthalide compounds, spiropyran compounds, rhodamine lactam compounds, lactone and dilactone compounds, benzoyl leuco methylene blue (BLMB), derivatives of bis-(p-di- alkylaminoaryl) methane, xanthenes, indolyls, auramines, chromenoindol compounds, pyrollo-pyrrole compounds, fluorene compounds, and fluoran and bisfluoran compounds, with fluoran compounds being preferred. Particularly preferred commercial leuco dye products include the Pergascript range by Ciba Speciality Chemicals, Basel, Switzerland and those by Yamada Chemical Co. Ltd, Kyoto, Japan. Others include those made by Nisso Chemical Co GmbH, a subsidiary of Nippon Soda Co. Ltd. Tokyo, Japan.

Charge transfer agents and leuco dyes are usually used in combination with an acid generating agent, particularly a photoacid generating agent. Examples of suitable compound include 'onium' types such as sulphonium and iodonium compounds. The present invention can be used to write text, characters, logos, trademarks, devices and other brand identification patterns onto a water-soluble capsule. Any suitable source of light/radiation can be used. The radiation can be monochromatic or broadband, laser or non-coherent. The method may involve imaging with a laser, which may be controlled by an IBM compatible computer. Imaging may alternatively be performed using a non-coherent energy source through a mask. Using non-contact energy to print images onto capsules prevents contact damage to the capsule which can occur with traditional printing processes.

Suitable lasers for use in image generation include UV, visible, NIR and CO ₂ lasers. The laser can have an emission wavelength is the range 120 nm to 20 microns. It can be a pulsed or continuous wave laser, an excimer, Nd:YAG, diode or diode array type.

The skilled person can select a suitable dye, or combination of dyes, according to the eventual colours required. The marking laser intensity, wavelength and/or time of exposure can all be varied to ensure that an appropriate colour is produced. WO2006/114594 describes an apparatus which includes a laser diode and galvanometer, and is suitable for aligning the laser beam onto the colour forming composition in the present invention. WO2007/039715 furthermore describes a method of inkless printing. As in these publications, the colour of the colour-forming composition in this invention is selectable according to the fluence level of the irradiation at a desired point.

The colour former may be included in the film in the form of a laser- imageable composition, which comprises the colour former and a binder. Further additives may include NIR absorbers, dispersing agents, acid- generators, UV absorbers/stabilizers, processing aids, co-solvents, whitening agents, foam suppressants etc.

The binder can be any known to those skilled in the art. Suitable examples include acrylics, methacrylics, urethanes, cellulosics such as nitrocelluloses, vinyl polyers such as acetates and butyrals, styrenics, polyethers, polyesters. The binder system can be aqueous or organic solvent based. Examples of the binder systems that can be employed include the Texicryl range supplied by Scott-Bader, the Paranol range supplied by ParaChem, the Pioloform range supplied by Wacker- Chemie, the Elvacite range supplied by Lucite International Inc., the Joncryl range supplied by Johnson Polymers, and the WitcoBond range supplied by Baxenden Chemicals.

As used herein, the term "coloured" refers to a formulation (for instance, the film or encapsulated composition, as the case may be) which appears coloured by virtue of colourants. The colourants may be conventional pigments or dyes, or alternatively, activated colour formers as detailed above. The term "transparent" is intended to mean any substance which is capable of letting light pass therethrough. "Transparent" may be used interchangeably with "visibly clear".

Examples of water-soluble capsules suitable for use in the present invention are described in WO03037741. The film is typically made from PVA, or is a water soluble cellulosic film. Typically, the film is transparent.

The composition within the capsule may be a fluid, liquid, gel, soft-solid, paste, powder or granules. It may a laundry composition such as a pre-wash agent, main wash agent, co-wash agent, fabric conditioner, freshener and the like. It may alternatively be a composition suitable for use in dishwashing for cleaning or treating crockery and the like. The composition is typically a unit dose of detergent. The composition may itself be transparent.

In one embodiment a capsule according to the invention contains a liquid detergent composition. When a liquid detergent composition is used, it is preferred that the composition is essentially non-aqueous. However, compositions may be used which contain substantial amounts of water, provided that this water is in a form where in its chemical activity is reduced (e.g. as water of crystallisation or in combination with a solvent such that its vapour pressure is reduced), such that the soluble film does not dissolve prematurely.

In one embodiment, the invention provides a water-soluble capsule comprising a transparent water-soluble film containing a transparent fluid, the capsule comprising a base wall portion inclined relative to one or more further wall portions, and the film comprising a coloured portion and a non-coloured portion and the coloured portion having a sufficiently large area in relation to the area of the non-coloured portion such that the non-coloured portion and the fluid appear coloured.

The effect of this arrangement is that only part of the capsule need be coloured in order to achieve a substantial coloured effect, i.e. so that more than the coloured part of the capsule appears coloured to the naked eye. Thus, the fluid can be made to appear coloured by colouring only part of the film thus using a reduced level of colourant (as compared with the levels required if colourants were to be added to the fluid). This reduces the cost - financial and environmental - and the likelihood of colourant-related staining of wash fabrics. At the same time, the film itself also appears coloured thereby enhancing its visual characteristics.

The present invention also has utility in pharmaceutical applications. The encapsulated composition may comprise, for instance, one or more pharmaceutically active ingredients.

The film may additionally comprise other agents such as traditional dyes and pigments, energy absorbing agents, and the like.

The energy used to activate the colour former may be non-coherent or laser radiation. The radiation may be monochromatic or broadband. The radiation is typically UV, visible, near-infrared or mid-infrared radiation (such as that provided by a CO ₂ laser). The radiation can have a wavelength in the region 120 nm to 20 microns. The laser can be pulsed or continuous wave.

Energy absorbing agents can be used to match the wavelength of energy used to activate the colour change reaction. These include, for example, UV absorbers for UV radiation, dyes and pigments for visible radiation and near infrared absorbers for near-infrared radiation. Suitable examples of near-infrared absorbers include copper (II) hydroxyl phosphate, reduced indium tin oxide, antimony tin oxide and coated micas thereof, conductive polymers and organic type near infrared absorbers such as N,N,N',N'-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoroantimonate).

Examples

Example 1 : PVA film comprising IQ.^-pentacosadivnoic acid.

A PVA film was made comprising 10,12-pentacosadiynoic acid 5% by weight.

The film was then used to produce capsules that further comprised the following detergent formulation.

The capsules were imaged/coloured as follows: 1. A broadband UV lamp was used to turn the capsule blue, followed by treatment with broadband near infrared light which subsequently turned it red.

2. A 266nm UV laser linked to an IBM compatible pc was use to write text, which could be read by the human eye, draw logos and devices on the film. Example 2: PVA film comprising 10.12-docosadivndioic acid proparqyldiamide A PVA film was made comprising 10,12-docosadiyndioic acid propargyldiamide (5% by weight) and a NIR absorbing dye (0.25%).

The film was then used to produce capsules that further comprised the detergent formulation shown in Example 1.

The capsules were imaged/coloured as follows: 1. The capsule was heat activated using a NIR fibre laser. 2. A broadband UV lamp was used to turn the capsule blue only in those parts that were initially heat activated, followed by treatment with broadband near infrared light which subsequently turned it red.