Composition and methods for colouring fibres

Abstract

A composition for colouring fibres, the composition comprising an aqueous medium, pigment particles dispersed in the aqueous medium, and a cationic functionalisation agent at least electrostatically adsorbed to the surface of the dispersed pigment particles. The cationic functionalisation agent is selected from cationic polyelectrolytes and cationic 5 surfactants, and the ratio of the pigment to cationic functionalisation agent is greater than about 10:1. The composition does not comprise polyethylenimine.

Description

[0001] COMPOSITION AND METHODS FOR COLOURING FIBRES

[0002] Field of the Invention

[0003] The present disclosure relates to a composition for colouring fibres, such as keratin fibres, the composition comprising a cationic functionalisation agent.

[0004] Background of the invention

[0005] The colouring of natural or synthetic fibres is well known. Dyeing treatments colour natural or synthetic fibres and change their appearance, texture and other physical properties.

[0006] Direct dyeing and oxidative dyeing are techniques for colouring hair and other fibres. However, these techniques may have disadvantages such as degradation of the fibres being coloured, irritation to the skin, lack of uniformity and irreversibility. One alternative for dyeing fibres is by the adherence of pigments to the surface of the fibre. An advantage of pigment dyeing, also referred to as pigment colouring, is that it is possible to colour dark fibres without prior bleaching, such as naturally dark coloured hair as the pigment composition generally attaches to the outside of the fibre. Typically, a pigment adhesion dyeing process comprises the provision of a composition comprising a pigment and a film-forming polymer. The composition comprising the pigment and film-forming polymer coats the hair and enables colouring without damage to the fibre. The film-forming polymer is generally a polymer that is capable of forming a continuous, cohesive film attached to the fibre.

[0007] However, the existing pigment compositions comprising film-forming polymers have drawbacks in that the film-forming polymer inherently alters the physical properties of each fibre and can result in each fibre possessing an artificial feeling. In particular, the fibres may have a heavy feeling, a rough feeling and a lacklustre appearance. Additionally, the fibres may be difficult to comb or brush.

[0008] Hair colouring compositions should avoid the use of components which are known, or suspected causes of irritation to mammals. For example, components which may cause irritation to the skin, eyes, respiratory tract etc. should be avoided to ensure consumer satisfaction and regulatory compliance, or even future regulatory compliance where regulations may be expected to become stricter. Improved pigment-based fibre dyeing compositions and processes would be advantageous.

[0009] Summary of the invention

[0010] Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a composition for colouring fibres. The composition comprises an aqueous medium, pigment particles dispersed in the aqueous medium, and a cationic functionalisation agent at least electrostatically adsorbed to the surface of the dispersed pigment particles. The cationic functionalisation agent is selected from cationic polyelectrolytes and cationic surfactants, and the ratio of the pigment to cationic functionalisation agent is greater than about 10: 1. The composition does not comprise polyethylenimine.

[0011] The use of the composition for pigment colouring of keratin fibres is provided.

[0012] Furthermore, a method for preparing a composition for colouring fibres is provided.

[0013] A method for colouring keratin fibres is provided.

[0014] Further advantageous embodiments are disclosed in the appended and dependent patent claims.

[0015] The present compositions and related methods provide colour intense pigment coatings that have a natural feel, sensoriality, and are water and sweat resistant, and resistant to abrasion and wear. Furthermore, as the compositions are non-film forming, they are rapidly appliable to fibres.

[0016] Detailed description

[0017] The composition described herein is based on the identification that fibres may be coloured by the provision of a pigment dispersion where the pigment particles in the dispersion are attachable to fibres through at least electrostatic, and ideally electrostatic and hydrophobic interactions in combination. To ensure that the pigment particles are at least electrostatically attachable to fibres, the pigment particles are functionalised with a cationic functionalisation agent. The fibres to be coloured may be for example, natural cellulose based fibres such as cotton, linen, or other cellulose based fibres; keratin fibres, such as human hair or wool. The composition is especially suitable for application to and colouring of keratin fibres, such as human hair.

[0018] The composition comprises pigment particles in a carrier medium. A cationic functionalisation agent is adsorbed to the surface of the dispersed pigment particles. The cationic functionalisation agent may be selected from cationic polyelectrolytes and cationic surfactants. The composition does not comprise polyethylenimine (PEI). The cationic functionalisation agent is not polyethylenimine (PEI). Polyethylenimine is a known irritant and may cause serious eye damage. Therefore, it is ideal of cosmetic compositions, such as hair colouring compositions, do not comprise polyethylenimine.

[0019] If the cationic functionalisation agent is a cationic polyelectrolyte, the cationic polyelectrolyte may be selected from cationically modified polysaccharides, chitosans, poly peptides and polyquats. If the cationic functionalisation agent is a cationic surfactant, the cationic surfactant may be selected from quaternary ammonium compounds, ester quats, cationic poly(amidoamine); cetrimonium chloride, behentrimonium chloride, or their respective methosulphate salts. Ideally, the cationic functionalisation agent is biobased due to user demands on natural ingredients within hair colouring compositions.

[0020] The cationic functionalisation agent is a cationic agent which is cationic over a range of typical pH values to which a hair colouring composition is subject to. For example, the cationic functionalisation agent is cationic from a pH of about 3 to a pH of about 12. The pigment and cationic functionalisation agent complex is ideally permanently cationic, that is it is cationic of the range of typical pH values to which a hair colouring composition is subjected to. The pigment and cationic agent complex may be cationic from a pH of about 3 to a pH of about 12.

[0021] Ideally, the cationic functionalisation agent is a cationically modified polysaccharide, such as a cationic modified guar gum, such as guar hydroxypropyltrimonium chloride.

[0022] The cationic functionalisation agent adsorbs to the surface of the pigment particles and provides the particles with a net positive surface charge. The present invention utilises the electrostatic binding between cationic functionalisation agent and the pigment, and subsequently the electrostatic binding between the pigment particle with the cationic functionalisation agent, and fibres having a net negative surface charge, to result in effective and natural feeling coating to fibres.

[0023] Ideally, the pigment is present at substantially greater amounts than the cationic functionalisation agent. The ratio between the amount of pigment and the cationic functionalisation agent may be greater than 1 : 1. The pigment is ideally present at an amount an order of magnitude greater than the cationic functionalisation agent in the composition. The ratio between the amount of pigment and the cationic functionalisation agent may be greater than about 10: 1, such as greater than about 30: 1, such as from about 30:1 to about 500: 1, such as from about 30: 1, to about 300: 1.

[0024] The composition may comprise less than about 1% by weight cationic functionalisation based on the total weight of the final composition. The composition may comprise less than about 0.5% by weight cationic functionalisation agent, such as less than about 0.25% by weight cationic functionalisation agent, such as about 0.1% by weight cationic functionalisation agent. The composition may comprise from about 0.01% to about 0.1% cationic functionalisation agent. As the cationic functionalisation adsorbs to the surface of the pigment particles, an excess of cationic functionalisation agent is not required and has not been shown to improve performance. On the contrary, a lower amount of cationic functionalisation agent has been shown to be optimum in terms of on-hair feel while still providing satisfactory cationic functionalisation of the pigment particles.

[0025] On-hair feel may be referred to as sensoriality. This on-hair feel relates to both the feel of the plurality of fibres taken as a whole, for example their perceived weight after treatment, and the feel of individual fibres, such as their ability to be separated from each, a lack of stickiness or waxiness etc.

[0026] The cationic functionalisation agent is provided in amount sufficient to provide cationic functionality to the dispersed pigment particles. The cationic functionalisation agent may be provided in an amount sufficient to provide cationic functionality to the pigment particles, and at an amount which does not provide a film coating to the fibre to be coloured. As can be seen in the experimental section, a composition which fixes to fibres has been demonstrated with only 0.1 w% cationic functionalization agent. The relatively low amount of polymer compared to known pigment compositions enables a more natural feeling to the coloured fibres and results in film-free pigment colouring of hair fibres.

[0027] To attach the cationic functionalisation agent to the pigment particles the pigment particles are dispersed in an aqueous medium. The pH of the dispersion is controlled or adjusted below the isoelectric point of the pigment particles, such that the pigment particles have a net positive surface charge. The isoelectric point of the pigment particles has been found to be from about 4-5. Therefore, the pH of the dispersion may be controlled or adjusted to below 5, such as below 4, such as from about 3 to about 4. The cationic functionalisation agent is thereafter provided to the dispersion with the positively charged pigment particles. The dispersion therefore comprises both positively charged pigment particles and the cationic functionalisation agent. The pH of the dispersion is thereafter increased above the isoelectric point of the pigment particles, such that the pigment particles posses a net negative surface charge. The charge of the cationic functionalisation agent is not changed by the adjusting of the pH above the isoelectric point of the pigment particles. The cationic functionalisation agent thereafter is at least electrostatically adsorbed to the surface of the pigment particles and the particles will effectively attach to the surface of the fibres, such as hair fibres.

[0028] When the cationic functionalisation agent is a polymer, the cationic functionalisation agent is substantially non-crosslinked. That is, the cationic functionalisation agent when in composition, and after provision to fibres, remains noncrosslinked. The non-crosslinking refers to the molecules of the cationic functionalisation agent not being crosslinked to each other. By avoiding crosslinking the cationic functionalisation agent, the natural feeling of the fibres is maintained. Furthermore, the colouring composition is removable via traditional fibre washing processes for example, shampooing, but remains resistant to rinsing via water as shown in the experimental section. The composition may be free from a crosslinking agent. That is, the composition may be free from known crosslinking agents such as photoinitiators, N-(3- Dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), tripolyphosphate, isocyanate. As described previously, the composition does not comprise polyethylenimine. As stated above, the cationic functionalisation agent is at least electrostatically adsorbed to the surface of the pigment particle. Within the composition, the majority, such as greater than 50%, such as greater than 80%, such as greater than 90%, such as greater than 95% of the cationic agent may be adsorbed to the surface of the pigment particle. The cationic functionalisation agent should not be freely dispersed throughout the composition, such as dispersed within the aqueous medium.

[0029] The composition for colouring fibres may be described as non-film forming. The term “non-film forming" refers to the pigment particles being present in a dispersion within the composition and remaining substantially separate when provided to the fibre to be coloured. The pigment particles are not present in a matrix on the hair but remain separate and dispersed, even after application to the fibres to be coloured. The composition does not comprise a film-forming agent. The composition does not comprise a film-forming polymer. Typical film-forming polymers known within the field of fibre colouring are copolymers of vinylpyrrolidone and vinyl acetate monomers, vinylpyrrolidone homopolymers, for example, VP / VA copolymer (or PVP / VA copolymer), PVP. The composition does not comprise the above listed film-forming agents.

[0030] The composition may advantageously be provided with at least one dispersant. The dispersant ensures that the pigment particles do not agglomerate in the composition and when provided to the fibre to be coloured. The dispersant may be for example, a nonionic, anionic, cationic, or amphoteric surfactant. As disclosed in the experimental section the dispersant may be a non-ionic surfactant. The dispersant may be known dispersants within cosmetics. The dispersant may be a lauryl ether or lauryl alcohol ethoxylate. At least two dispersants may be provided to the composition, such as a mixture of alcohol ethoxylates. The dispersant may be present in the composition at an amount of less than 5% (wt. / wt.) with respect to the total weight of the composition.

[0031] The composition may comprise a wetting agent to aid the dispersion of the pigment particles within the aqueous carrier medium. The wetting agent may be dipropylene glycol dimethyl ether, or polyethylene glycol (PEG), such as PEG-200. The wetting agent may be provided at an amount of from about 0.2% (wt. / wt.) to about 10% (wt. / wt.), such as from about 1% (wt. / wt.) to about 5% (wt. / wt.), such as from about 1.5% (wt. / wt.) to about 4% (wt. / wt.), such as from about 2% (wt. / wt.) to about 3% (wt. / wt.).

[0032] The composition and / or a pre-treatment composition ideally comprises at least one hydrophobic additive to aid spreading of the pigment and cationic agent over the hair surface. The hydrophobic additive may be provided to the composition, and / or as a pretreatment step in a pre-treatment composition separate from the colouring composition. The hydrophobic additive may be selected from for example, cetyl alcohol, castor oil, dicaprylyl carbonate and propylheptyl caprylate. Without intending to be bound by theory, the hydrophobic additive may introduce capillary bridges between the pigment and the surface of the fibre which increases the adhesion force. As shown in the experimental section, the addition of the hydrophobic additive increased the colour intensity of the pigment colouring composition and improves the on-hair feel. The hydrophobic additive may advantageously be dicaprylyl carbonate. The hydrophobic additive, such as dicaprylyl carbonate may ideally be provided at an amount of less than 10% based on the total weight of the composition, such as less than about 5% (wt. / wt.), such as less than about 1 % (wt. / wt.), such as less than about 0.5% (wt. / wt.), such as about 0.3 (wt. / wt.). If the hydrophobic additive is provided in a pre-treatment composition, the hydrophobic additive in the pre-treatment composition may be provided at an amount of less than about 10% based on the total weight of the pre-treatment composition, such as about 5% (wt. / wt.).

[0033] If the method for colouring fibres comprises a pre-treatment step with a pretreatment composition comprising a hydrophobic additive, then the pre-treatment step is performed prior to application of the colouring composition. The pre-treatment step is ideally performed less than about 1 hour, such as less than about 30 mins before application of the colouring composition.

[0034] As used herein the term pigment refers to any water-insoluble particle colourant comprising or containing pigment material that colours fibres, such as keratin fibres. The particular pigment particle, or combination of pigment particles, is selected based on the desired colour to be provided to the fibre, and any additional visual / appearance performance features also desired. The present composition is, however, suitable with various pigments, both organic and inorganic, combinations of organic pigments, combination of inorganic pigments or combinations of organic and inorganic pigments.

[0035] The pigment particles may be chosen from the inorganic and organic pigments known within the field of fibre colouring. The pigment particle may be an inorganic or organic pigment particle coated with an additional coating layer, that is, the pigment is coated with an additional layer not providing any cationic functionalisation. The pigment particles can be in the form of a powder or a paste. The pigment may be a mineral pigment, an organic pigment, an elemental metal or a metal oxide, a lake pigment, a composite inorganic-organic pigment such as a nacre, or a mixture thereof.

[0036] Inorganic pigments are especially ideal for the pigment particles of the present composition. Inorganic pigments display generally improved resistance to light (both visible and ultraviolet), weather and temperature. Inorganic pigments may be white pigments such as titanium dioxide or zinc oxide, coloured pigments such as red iron oxide. The pigment particles may be selected from metal oxides, hydroxides and oxide hydrates, mixed phase pigments, sulphur-containing silicates, metal sulphides, complex metal cyanides, metal sulphates, chromates and molybdates, alloys, and the elemental metals themselves. The pigment(s) can be selected from stearate coated or siliconized inorganic pigments. The pigment(s) can be selected from the group consisting of titanium dioxide (Ci 77891), black iron oxide (Ci 77499), yellow iron oxide (Ci 77492), red and brown iron oxide (Ci 77491), siliconised iron oxide, manganese violet (Ci 77742), ultramarine (sodium aluminum sulfo silicates, Ci 77007, Pigment Blue 29), chromium oxide hydrate (Ci 77289), Prussian blue (ferric ferrocyanide, Ci 77510), lake carmine (cochineal), zinc sulfide, barium sulfate, zinc oxide, siliconised titanium dioxide, siliconised zinc sulfide, siliconised zinc oxide, and mixtures thereof. The pigment(s) can be selected from the group consisting of iron oxide, titanium dioxide, mica, borosilicate, and combinations thereof. The pigment can comprise an iron oxide (Fe2O3) pigment.

[0037] The pigment may be an organic pigment. Organic pigments are organic compounds and have a variety of structures, compositions and therefore colours. The organic pigment be nitroso, nitro, azo, xanthene, quinoline, anthraquinone, phthalocyanin, copper phthalocyanin, copper hexadecachlorophthalocyanine, 2-[(2- Methoxy-4-nitrophenyl)azo]-N-(2-methoxyphenyl)-3-oxobutyramide, metal-complex, isoindolinone, iso indo line, quinacridone, perinone, perylene, diketopyrrolopyrrole, thio indigo, dioxazine, triphenylmethane, dimethylquinacridone and quinophthalone compounds, Azo-dyes, Nonionic azo dyes, Anionic Azo dyes, Cationic azo dyes, Complex forming azo dye, aza annulene dyes, aza analogue of diarylmethane dyes, aza annulene dyes, Nitro-dyes and their pigments, Carbonyl dyes and their pigments (for example, Anthrachinon dyes, indigo), Sulphur dyes, Florescence dyes, Anthracene or Insoluble alkali or earth metal acid dyes. The organic pigment may be any known organic pigment. When the pigments are dyes, then water-insoluble forms of the dyes, or dyes in the form of lake pigments are suitable for use with the present invention.

[0038] The pigment particles may be hydrophobic pigment particles, generally this refers to pigment particles that have been modified or treated to provide hydrophobicity. The pigment particles may be hydrophilic pigment particles, for example, inorganic metal oxides are hydrophilic pigment particles.

[0039] The pigment particle may take a variety of forms and shapes depending on the specific pigment and whether it is coated or treated. The pigment particle with the cationic functionalisation agent has a substantially similar particle size and shape when compared to the pigment prior to cationic functionalisation. If the pigment particle is spherical, the pigment particle may have a diameter, such as a D50(vol) diameter, of approximately 10 nm to several pm. The pigment particle typically has a D50(vol) diameter of approximately 50 nm to 1000 nm, such as from about 50 nm to about 500 nm.

[0040] As shown in the experimental section, the hydrodynamic diameter of the pigment particles with the cationic functionalisation agent attached in aqueous dispersion is ideally less than about 450 nm measured by dynamic light scattering. The hydrodynamic diameter is ideally less than about 400 nm, such as less than about 350 nm. The smaller pigment particle diameter produces improved colouring results. Furthermore, spherical, and in particular non-rod-shaped, pigment particles have been shown to provide the best colour intensity with the present colouring composition. The dynamic light scattering measurement is ideally performed with a submicron particle analyser (Beckman Coulter, N4 Plus)

[0041] Different pigment particles may be combined to achieve improved visual appearance of the coloured fibres. For example, a combination of at least two different pigment materials to form a combined pigment mixture. The combined pigment mixture may provide improved reflective, refractive and light transmitting properties to the coloured fibre.

[0042] The zeta potential of the pigment particle may change depending on the pH of the carrier medium in which it is present.

[0043] The composition may comprise the pigment particles at an amount of from about 0.01% (wt. / wt.) to about 20% (wt. / wt.) with respect to the total weight of the composition, such as from about 0.1% (wt. / wt.) to about 10% (wt. / wt.), such as from about 1% to about 5%, such as about 3% (wt. / wt.).

[0044] The carrier medium of the composition may be an aqueous carrier medium. The composition may be considered an aqueous composition comprising the pigment particles and the cationic functionalisation agent. The composition may comprise the carrier medium at an amount of from about 50% (wt. / wt.) to about 99% (wt. / wt.) with respect to the total weight of the composition, such as from about 80% (wt. / wt.) to about 99% (wt. / wt.), such as from about 93% (wt. / wt.) to about 98% (wt. / wt.) carrier medium. The carrier medium may be water.

[0045] The composition may be a liquid dispersion, a gel dispersion, a cream dispersion or any other form which is suitable for applying to the fibres to be treated.

[0046] The composition is a ready-to-use composition, the term “ready-to-use” refers to the composition being suitable for direct application to the fibres to be treated. The composition is provided in a form which is suitable for use directly and is does not result from the mixing of, for example, several separate components in conjunction with application to the fibres to be treated.

[0047] The composition may optionally include, or optionally exclude, one or more miscellaneous ingredients. Miscellaneous ingredients are ingredients that are compatible with the cosmetic compositions and do not disrupt or materially affect the attachment of pigment particles of the compositions. Nonlimiting examples of miscellaneous ingredients include preservatives, fragrances, antioxidants, flavonoids, vitamins, botanical extracts, UV filtering agents, proteins, protein hydrolysates and / or isolates.

[0048] The total amount of the one or more miscellaneous ingredients, if present, will vary. Nonetheless, in various embodiments, the composition may comprise from about 0.001% (wt. / wt.) to about 10% (wt. / wt.) of one or more miscellaneous ingredients, with respect to the total weight of the composition.

[0049] To colour the fibres, the composition may be applied to the fibres, such as keratin fibres, according to the following process: the composition is applied to the fibres, the composition may be applied via direct application via a brush, spray etc. or washed-in via for example, a shampoo comprising the present composition; and the composition is left to act on the fibres for a period form about 30 seconds to about 48 hours. The composition may be optionally dried, such as via blow drying.

[0050] The pigment particles are thereby attracted via at least electrostatic interaction and van der Wais forces to the fibres and remain attached to the fibres.

[0051] The present composition is ideally what is known within the field as a “leavein” composition whereby a post-application rinsing step is not necessary for activating the colour. As the pigment particles are attracted to the fibres via at least electrostatic interaction the pigment particles provide an external coating to the fibre the colour is provided to the fibre directly on application of the composition. The external coating refers to a dispersed layer of pigment particles attached to the outside of the fibres, and does not refer to a continuous cohesive film coating the entire, or majority of, the fibre. As the present composition is non-film forming, it can be applied rapidly without waiting for film formation, e.g., crosslinking, processes to be completed.

[0052] The composition may be applied to wet or dry fibres. The fibres, such as keratin fibres, may be washed prior to application of the fibres. The composition may be applied to the fibres at room temperature.

[0053] The fibres may be pre-treated with a pre-treatment composition to improve colour fastness, intensity etc. In particular, the fibres may be pre-treated with a pretreatment composition comprising the hydrophobic additive as described previously. In such an application process, the pre-treatment composition comprising the hydrophobic additive is applied directly to the fibres prior to the application of the colouring composition. Experimental Section

[0054] Experiment 1 - Comparison of compositions and control compositions

[0055] Composition 1 - hydrophobically modified red iron oxide pigment with cationic functionalisation

[0056] A composition according to the above table was prepared as follows.

[0057] The pigment and wetting agent were weighed and sonicated in a bath for 1 minute to prepare a homogenous slurry. The dispersant and water were added and sonicated to disperse the pigment. The pH of the dispersion was adjusted to about 4 such that it was below the isoelectric point of the pigment, resulting in the pigment having a net positive surface charge. The cationic functionalisation agent was added and the dispersion was stirred for 10 minutes. The pH of the dispersion was adjusted above the isoelectric point of the pigment, in the above case about pH 7, so that the pigment has a net negative surface charge. The dispersion was stirred for up to 12 hours, such that the cationic functionalisation agent electrostatically binds to the surface of the pigment. The hydrophobic additive was added directly to the dispersion and the dispersion was mixed.

[0058] Composition 2 - hydrophilic red iron oxide pigment with cationic functionalisation

[0059] A composition was prepared according to the table above. The composition was prepared according to the process described in composition 1, with the modification that the dispersant and wetting agent were excluded due to the hydrophilic nature of the pigment particles.

[0060] Composition 3 - hydrophilic white titanium dioxide pigment with cationic functionalisation

[0061] To determine the performance with a pigment of a different colour, a composition was prepared according to the table above. The composition was prepared according to the process described for composition 1, and as with composition 2, no dispersant or wetting agent was necessary.

[0062] Composition 4 - hydrophilic yellow iron oxide pigment with cationic functionalisation

[0063] A composition was prepared in order to determine performance with yellow pigment particles. The composition was prepared according to the table above with the process as described for composition 1, and as with compositions 2 and 3, the composition comprised no dispersant or wetting agent.

[0064] Composition 5 - Control hydrophobic pigment composition without cationic functionalisation agent nor hydrophobic additive

[0065] Composition 6 - Control hydrophilic pigment composition without cationic functionalisation agent nor hydrophobic additive.

[0066] Application of composition to hair samples

[0067] Each of the above compositions were applied to hair swatches. Prior to application of the colouring compositions, the hair swatches were washed with a normal shampoo. The swatches were towel dried and the composition was applied to the damp hair swatches. Comparison o f results

[0068] The compositions were applied via both leave-in colouring and rinse-off colouring. In leave-in colouring the colouring composition applied and then immediately dried in either ambient conditions or using a hair drier. In rinse off colouring the colouring composition is provided to the hair and then incubated for up to 10 minutes, and subsequently rinsed off with water. No significant differences to the performance for either colouring process, leave-in and rinse-off, for compositions 1 and 2, that is, the compositions with cationic functionalisation. Compositions 1 and 2 were both water resistant, and the coloured hair swatch can be held under running water while maintaining its colour intensity. As can be seen in the above results, the compositions with cationic functionalisation showed improved performance compared to the respective control compositions. The relatively low amount of cationic functionalisation agent leads to the pigment particles dispersing and maintaining separation on the hair which results in improved on-hair feel, sensoriality, to compositions comprising significantly greater amounts of cationic functionalisation agent which tend to have a film-like on-hair feel or a decreased colour intensity. Experiment 2 - Comparison of pigment sizes

[0069] To compare the performance of different pigments, and in particular pigment sizes several compositions were prepared. The size and form of the pigment particles was analysed via microscopy. The pigment particles were dispersed in an aqueous medium. The hydrodynamic diameter of the pigment particles was determined via dynamic light scattering microscopy, and the colouring performance was analysed.

[0070] The hydrophobically modified pigment particles were dispersed in the following composition.

[0071] The hydrodynamic diameter of the dispersed hydrophobic pigment particles was analysed via dynamic light scattering, the results of the analysis is shown in the table below. On application of the compositions to hair swatches, the hydrophobic red iron oxide pigments 1 and 2 showed good colour intensity and transfer resistance. The hydrophobic modified pigment 3 which could only be dispersed to a diameter of about 450 nm showed significantly decreased colour intensity and poorer transfer resistance. The unmodified and hydrophilic pigment particles were dispersed in the following composition. The hydrodynamic diameter of the dispersed unmodified hydrophilic pigment particles was analysed via dynamic light scattering, the results of the analysis is shown in the table below. On application of the composition to hair swatches, the unmodified and hydrophilic red iron oxide 1 displayed good colour intensity and transfer resistance which were similar to the results for the hydrophobic pigments 1 and 2. However, the unmodified hydrophilic iron oxide 2 displayed poorer results with lower colour intensity and poor transfer resistance.

[0072] Experiment 3 - Comparison of cationic functionalisation agents

[0073] To compare the performance of different cationic functionalisation agents the following compositions were prepared.

[0074] The performance of the various cationic functionalisation agents were compared by applying the compositions to hair swatches as previously described with both leave-in and rinse colouring performed and compared. The results are provided in the table below. As can be seen from the above table, of the compared cationic functionalisation agents, the cationic guar gum CA-3001 performed best with respect to both colour intensity and transfer resistance with both leave-in and rinse-off application methods. The on-hair feel was similar for each of the cationic functionalisation agents.

[0075] Experiment 4 - Comparison of dispersants To determine an ideal dispersant system, the following dispersant compositions were prepared with 3% wt. hydrophobically modified red iron oxide 1 from experiment 2. No cationic functionalisation agents were added to the compositions.

[0076] SI : 1.3 wt% Croda Brij L4 + 2.3 wt% Croda Brij L23

[0077] S2: 4.4 wt% Nouryon AG-6206 + 1.6 wt% Croda Brij L4 S3: 0.8 wt% Croda Brij L23 + 4 wt% Croda Brij CIO

[0078] S4: 1.2 wt% Nouryon AG-6206 + 8.4 wt% Croda Brij CIO The hydrodynamic diameter of the dispersed pigment particles was determined via dynamic light scattering and compared. The dynamic light scattering measurement was performed with a submicron particle analyser (Beckman Coulter, N4 Plus). The results are provided in the table below.

[0079] The dispersant mixture SI showed the smallest hydrodynamic diameter. Experiment 5 - Comparison of hydrophobic additives

[0080] To compare the results when providing a hydrophobic additive to the composition, or when pre-treating the hair swatch with a hydrophobic additive. The colouring composition was prepared according to the following table. The following hydrophobic additives were compared to each other and to a control without any hydrophobic additive:

[0081] • Cetyl alcohol (Supplier: Sigma-Aldrich)

[0082] • Castor oil (Supplier: Sigma-Aldrich)

[0083] • Dicaprylyl carbonate, Cetiol CC (Supplier: BASF) Propylheptyl caprylate, Cetiol SENSOFT (Supplier: BASF)

[0084] Cetyl alcohol was added to the pigment dispersion in the form of pre-dispersed solid microparticles. The microparticles were prepared by homogenization of 30 wt.% cetyl alcohol in an aqueous phase containing 1 wt.% Brij L23 and 1 wt.% Brij CIO, heated to 60 °C, for 5 minutes and then cooled down to room temperature. In the final colouring formulation, an amount corresponding to 0.3 wt.% cetyl alcohol was added.

[0085] The remaining hydrophobic additives were added as a pretreatment step on the hair swatches from a 10 wt.% solution in ethanol (50 pl on a hair sample of 4 cm).

[0086] The colour intensity was increased after addition of all the hydrophobic additives. The transfer resistance was slightly decreased with all hydrophobic additives.

[0087] Each of the hydrophobic additives improve the on-hair feel, i.e., sensoriality of the coloured hair swatches as compared to an untreated reference sample, making it smoother and easier to run the fingers through. The best result was obtained after adding Cetiol CC. It was attempted to increase the concentration of Cetiol CC / ethanol from 50 pl to 100 pl, but this produced an unpleasant and oily, but not sticky / waxy, feeling on the hair. The cetyl alcohol (solid at room temperature while the others are liquid) produces a slightly rough feeling on the hair and was deemed the to provide the lowest increase in on-hair feel. Addition of castor oil produced a hair that felt sticky and waxy, but not oily.

[0088] Although, the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims.

[0089] In the claims, the term “comprises / comprising” does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and / or advantageous. In addition, singular references do not exclude a plurality. The terms “a”, “an”, “first”, “second” etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims

CLAIMS1. A composition for colouring fibres, the composition comprising:- an aqueous medium;- pigment particles dispersed in the aqueous medium; and,- a cationic functionalisation agent at least electrostatically adsorbed to the surface of the dispersed pigment particles; wherein the cationic functionalisation agent is selected from cationic polyelectrolytes and cationic surfactants, and wherein the ratio of the pigment to cationic functionalisation agent is greater than about 10: 1, and wherein the composition does not comprise polyethylenimine.

2. The composition for colouring fibres according to claim 1, wherein the cationic polyelectrolyte is selected from cationically modified polysaccharides, chitosans, poly peptides, polyquats or wherein, the cationic surfactant is selected from quaternary ammonium compounds, ester quats, cationic poly(amindoamine); cetrimonium chloride, behentrimonium chloride, or their respective methosulphate salts.

3. The composition for colouring fibres according to claim 2, wherein the cationic functionalisation agent is a cationically modified polysaccharide.

4. The composition for colouring fibres according to any of claims 1 to 3, wherein the ratio of the pigment to the cationic functionalisation agent is greater than about 30: 1, such as from about 30: 1 to about 500: 1, such as from about 30: 1 to about 300: 1.

5. The composition for colouring fibres according to any of claims 1 to 4, wherein composition comprises less than about 1% cationic functionalisation agent, such as less than about 0.5%, such as less than about 0.2%, and preferably about 0.1%.

6. The composition for colouring fibres according to any of claims 1 to 5, wherein the cationic functionalisation agent is substantially non-crosslinked, and / or wherein the composition does not comprise a crosslinking agent.

7. The composition for colouring fibres according to any of claims 1 to 6, wherein the composition comprises at least one dispersant and / or wetting agent.

8. The composition for colouring fibres according to any of claims 1 to 7, wherein the hydrodynamic diameter of the pigment particles with the cationic functionalisation agent adsorbed to their surface is less than about 450 nm, such as less than about 400 nm, such as less than about 350 nm.

9. The composition for colouring fibres according to any of claims 1 to 8, wherein the composition comprises at least one hydrophobic additive.

10. The composition for colouring fibres according to claim 9, wherein the hydrophobic additive selected from cetyl alcohol, castor oil, dicaprylyl carbonate, propylheptyl caprylate.

11. The composition for colouring fibres according to any of claims 1 to 10, wherein the composition comprises pigment at an amount of from about 1% to about 5% by total weight of the composition.

12. The composition for colouring fibres according to any of claims 1 to 11, wherein the composition is for colouring keratin fibres.

13. Use of the composition according to any of claims 1 to 12 for pigment colouring of keratin fibres.

14. A method for preparing a composition for colouring fibres, the method comprising: - dispersing a pigment in an aqueous medium creating a dispersion of pigment particles in the aqueous medium,- adjusting or controlling the pH of the dispersion below the isoelectric point of the pigment such that the pigment has a net positive charge surface charge,- providing a cationic functionalisation agent selected from cationic polyelectrolytes and cationic surfactants to the dispersion, wherein the composition does not comprise polyethylenimine,- increasing the pH of the dispersion above the isoelectric point of the pigment such that the pigment has a net negative surface charge, thereby at least electrostatically binding the cationic functionalisation agent to the pigment particle.

15. The method for preparing a composition according to claim 14, wherein the cationic polyelectrolyte is selected from cationically modified polysaccharides, chitosans, poly peptides, polyquats or wherein, the cationic surfactant is selected from quaternary ammonium compounds, ester quats, cationic poly(amindoamine); cetrimonium chloride, behentrimonium chloride, or their respective methosulphate salts.

16. The method for preparing a composition for colouring fibres according to claim 14 or 15, wherein the cationic functionalisation agent is a cationically modified polysaccharide.

17. The method for preparing a composition for colouring fibres according to any of claims 14 to 16, wherein the pigment and the cationic functionalisation agent are provided at a pigment to cationic functionalisation ratio of greater than about 10: 1, such as greater than about 30: 1, such as from about 30: 1 to about 500: 1, such as from about 30: 1 to about 300:1.

18. The method for preparing a composition for colouring fibres according to any of claims 14 to 17, wherein composition comprises less than about 1% cationic functionalisation agent, such as less than about 0.5%, such as less than about 0.2%, and preferably about 0.1%.

19. The method for preparing a composition for colouring fibres according to any of claims 14 to 18, wherein the hydrodynamic diameter of the pigment particles is less than about 450 nm, such as less than about 400 nm, such as less than about 350 nm.

20. The method for preparing a composition for colouring fibres according to any of claims 14 to 19, wherein the composition comprises at least one hydrophobic additive.

21. The method for preparing a composition for colouring fibres according to claim 20, wherein the hydrophobic additive selected from cetyl alcohol, castor oil, dicaprylyl carbonate, and propylheptyl caprylate.

22. The method for preparing a composition for colouring fibres according to any of claims 14 to 21, wherein the composition comprises pigment at an amount of from about 1% to about 5% by total weight of the composition.

23. The method for preparing a composition for colouring fibres according to any of claims 14 to 22, wherein the process does not comprise the step of crosslinking the cationic functionalisation agent molecules to each other.

24. A method for colouring keratin fibres, comprising,- preparation of a composition for colouring fibres according to the process to any of claims 14 to 23 or provision of a composition for colouring fibres according to any of claims 1 to 13,-application of the composition to the keratin fibres.

25. The method for colouring keratin fibres according to claim 24, wherein the method comprises, prior to the application of the composition to the keratin fibres:- applying a pre-treatment composition comprising a hydrophobic additive to the keratin fibres,wherein, the application of the pre-treatment composition is performed less than one hour, such as less than 30 minutes before the application of the composition for colouring fibres.

26. The method for colouring keratin fibres according to claim 25, wherein the hydrophobic additive is selected from cetyl alcohol, castor oil, dicaprylyl carbonate, and propylheptyl caprylate.

27. The method for colouring keratin fibres according to claim 26, wherein the hydrophobic additive is dicaprylyl carbonate, and wherein the pre-treatment composition comprises dicaprylyl carbonate at an amount of less than 10% with respect to the total weight of the pre-treatment composition.

28. The method for colouring keratin fibres according to any of claims 24 to 27, wherein the method does not comprise a step of crosslinking the cationic functionalisation agent molecules to each other.

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