Patent Description:
It is known to incorporate encapsulated functional materials in consumer products, such as household care, personal care and fabric care products. Functional materials include for example perfume materials, cosmetic materials, drug materials, and substrate enhancers.

Microcapsules that are particularly suitable for delivery of such functional materials are core-shell microcapsules, wherein the core comprises the functional material and the shell is impervious or partially impervious to the functional material. Usually, these microcapsules are used in aqueous media and the encapsulated functional materials are hydrophobic. A broad selection of shell materials can be used, provided this shell material is impervious or partially impervious to the encapsulated functional material.

Among the functional materials, perfume materials are encapsulated for a variety of reasons. Microcapsules can isolate and protect perfume ingredients from external suspending media, such as consumer product bases, with which they may be incompatible or unstable in. They are also used to assist in the deposition of perfume materials onto substrates, such as skin, hair, fabrics or hard household surfaces. They can also act as a means of controlling the spatiotemporal release of perfume.

Thermosetting resins are common shell materials for such perfume compositions. Core-shell microcapsules formed from aminoplast resins, polyurea resins, polyurethane resins, polyacrylate resins and combinations thereof are generally quite resistant to fragrance leakage when dispersed in aqueous suspending media, even in surfactant-containing media. Furthermore, when incorporated into consumer products, such as laundry detergents or conditioners, they provide perfumery benefits that are unattainable if the perfume is incorporated directly into those products.

In many instances, however, the deposition and adherence of these microcapsules on smooth surfaces and especially on keratinous surfaces, such as skin and hair, are insufficient and the expected benefits associated with the use of microcapsules are not optimal. This is especially the case for rinse-off products involving large amounts of water. In this case, a lack of deposition may be due to the dilution of the microcapsules. Large volumes of rinse water may also wash off the microcapsules from the surface.

<CIT> discloses a benefit agent delivery particle comprising a benefit agent and a chitosan salt at the outer surface of the particle which have good deposition efficiency on tip hair.

<CIT> discloses benefit agent delivery particles coated with a chitosan salt, which comprises a chitosan component and an organic anion. These particles have been shown to exhibit improved deposition compared to unmodified particles. However, their production requires a rather elaborate pre-formation of a chitosan complex which is then attached to the outer surface of the particles.

It is therefore a problem underlying the present invention to overcome the above-mentioned shortcomings in the prior art. In particular, it is a problem underlying the present invention to provide consumer products comprising microcapsules that show enhanced deposition on keratinous substrates and improved rinse resistance once deposited on these substrates. The microcapsules should be facile to manufacture and versatile with respect to their application. No or only minimal modification of the product composition should be required in connection with their use.

In a first aspect of the present invention, there is provided a consumer product comprising a plurality of microcapsules dispersed in a dispersing medium. The microcapsules comprise a core and a shell around the core. The core comprises at least one functional material. The shells of the microcapsules are coated with chitosan. The dispersing medium comprises additional free chitosan, wherein the chitosan that is coating the shells of the microcapsules and the free chitosan comprised in the dispersing medium have different average molecular weights.

Chitosan is a biopolymer derived from chitin, forming the exoskeleton of crustaceans and preserving the shape of various fungi, such as Ascomycetes, Zygomycetes, Basidiomycetes and Deuteromycetes, for example Absidia, Mucor, Aspergillus niger, Ganoderma lucidum, Rhizopus oryzae, and the like. Chitosan production involves the alkaline or enzymatic deacetylation of chitin and is characterized by a deacetylation grade. Both low deacetylation grades, typically below <NUM> % deacetylation, and high deacetylation grades, typically higher than or equal to <NUM>% deacetylation exist. Deacetylated chitosan is a copolymer consisting of N-acetyl-D-glucosamine an D-glucosamine moieties. The deacetylation grade may be determined by <NUM>H and/or <NUM>C nuclear magnetic resonance spectroscopy. Chitosan is available with molecular weights typically ranging from <NUM>'<NUM> and <NUM>'<NUM>'<NUM>/mol. The molecular weight may be determined by viscosity measurement and/or gel permeation chromatography, according to methods known in the art.

In the context of the present invention, the term "free chitosan" is used to describe chitosan which, when the microcapsules are dispersed in a dispersing medium, is separated spatially from the microcapsules by the dispersing medium.

As used herein, a "consumer product" means an article intended to be used or consumed in the form in which it is sold, and not intended for subsequent commercial manufacture or modification.

That the shells of the microcapsules are "coated"with chitosan means that the chitosan can be deposited on the shells. On the other hand, the chitosan can also be grafted on or entrapped in the shell of the microcapsules. Grafting and entrapment may be performed by adding the chitosan to the slurry of nascent microcapsules, meaning during the process step where encapsulation place. Alternatively, the chitosan may be grafted on the shell of the formed microcapsule by using coupling agents known to the art.

In the context of the present invention, the at least one functional material is particularly selected from the group consisting of a perfume material and a cosmetic material.

In advantageous embodiments of the present invention, the free chitosan comprised in the dispersing medium has a deacetylation grade higher than <NUM>%, more particularly higher than <NUM>%, still more particularly higher than <NUM>%. Chitosans with such high deacetylation grades are more soluble than chitosans having lower acetylation grades and therefore more suitable for the sake of the present invention.

In other advantageous embodiments, the free chitosan comprised in the dispersing medium has a molecular weight between <NUM>'<NUM> and <NUM>'<NUM>'<NUM>/mol, more particularly between <NUM>'<NUM>'000and <NUM>'<NUM>'<NUM>/mol, still more particularly between <NUM>'<NUM>'000and <NUM>'<NUM>'<NUM>/mol. Without being bound by any theory, it is reasonable to assume that high molecular weight chitosan adheres better on both keratinous surfaces, in particular hair, and microcapsules.

In other advantageous embodiments of the present invention, the chitosan that is coating the shells of the microcapsules has a deacetylation grade between <NUM>% and <NUM>%, more particularly between <NUM>% and <NUM>%, still more particularly between <NUM>% and <NUM>%. Aqueous solutions of chitosans with such high deacetylation grades are more concentrate and therefore more suitable for coating.

The chitosan that is coating the shells of the microcapsules and the free chitosan comprised in the dispersing medium have different average molecular weights.

The chitosan that is coating the shells of the microcapsules can have a molecular weight between <NUM>'000and <NUM>'<NUM>'<NUM>/mol, more particularly between <NUM>'000and <NUM>'<NUM>/mol, still more particularly between <NUM>'<NUM> and <NUM>'<NUM>/mol. If the molecular weigt of the chitosan is too low, then the coating may be incomplete, whereas if this molecular weight is too large, then chitosan threads may adsorb on two or more microcapsules and cause microcapsule agglomeration.

The electrical charge present on the microcapsules may be determined by measuring the zeta-potential of these microcapsules. By "zeta-potential" (ζ) is meant the apparent electrostatic potential generated by any electrically charged objects in solution, as measured by specific measurement techniques. A detailed discussion of the theoretical basis and practical relevance of the zeta-potential can be found, e.g., in "<NPL>). The zeta-potential of an object is measured at some distance from the surface of the object and is generally not equal to and lower than the electrostatic potential at the surface itself. Nevertheless, its value provides a suitable measure of the capability of the object to establish electrostatic interactions with other objects present in the solution, such as surfactants, polyelectrolytes and surfaces. The zeta-potential is a relative measurement and its value depends on the way it is measured. In the present case, the zeta-potential of the microcapsules is measured by the so-called phase analysis light scattering method, using a ZetaPALS instrument (ex Brookhaven Instruments Corporation). The zeta-potential of a given object may also depend on the quantity of ions present in the solution. The values of the zeta-potential specified in the present application are measured in an aqeuous buffer solution at desired pH. The ion concentration is <NUM> mol/L.

In advantageous embodiments of the present invention, the coated microcapsules have a zeta potential of:.

Without being bound by theory, it is assumed that, with such pH dependence of the zeta potential, optimal conditions for both coating at pH below <NUM> and free chitosan-mediated adhesion on keratinous surface at pH <NUM> or above are achieved.

In advantageous embodiments of the present invention, the microcapsules have volume-average size from <NUM> to <NUM> micrometres, more particularly from <NUM> to <NUM> micrometres, still more particularly from <NUM> to <NUM> micrometres, for example <NUM> ± <NUM> micrometres. Microcapsules having such size provide optimal balance between storage stability with respect to leakage of the encapsulated functional material, depostion on hair and mechanical frangibility.

Microcapsule size can be determined in a manner known in the art. A particular method of measuring particle size is light scattering. Light scattering measurements can be made using a Malvern Mastersizer <NUM> instrument and the Mie scattering theory. The principle of the Mie theory and how light scattering can be used to measure droplet size and can be found, for example in H. van de Hulst, Light scattering by small particles. Dover, New York, <NUM>. The primary information provided by static light scattering is the angular dependence of the light scattering intensity, which in turn is linked to the size and shape of the droplets. However, in a standard operation method, the size of a sphere having a size equivalent to the size of the diffracting object, whatever the shape of this object, is calculated by the Malvern proprietary software provided with the apparatus. In case of polydisperse samples, the angular dependence of the overall scattering intensity contains information about the size distribution in the sample. The output is a histogram representing the total volume of droplets belonging to a given size class as a function of the capsule size, whereas an arbitrary number of <NUM> size classes can be chosen. Thus, the size obtained is referred to as volume-average particle size.

Experimentally, a few drops of slurry are added to a circulating stream of degassed water flowing through a scattering cell. The angular distribution of the scattering intensity is measured and analysed by Malvern proprietary software to provide the average size and size-distribution of the droplets present in the sample. In the case of an unimodal (monodisperse) droplet distribution the percentiles Dv(<NUM>), Dv(<NUM>) and Dv(<NUM>) are used as characteristics of the droplets size distribution, whereas Dv(<NUM>) corresponds to the median of the distribution and is taken as a measure of the volume-average size of the microcapsules.

In advantageous embodiments, microcapsules, in particular with a volume-average size of <NUM> ± <NUM> micrometres, have an chitosan coating to encapsulated functional material ratio is from about <NUM> to about <NUM>, more particularly from about <NUM> to about <NUM>. Such chitosan coating to encapsulated functional material provides the desired pH-dependence of the zeta-potential described herein above.

In particular advantageous embodiments of the invention, the dispersing medium additionally comprises an anionic surfactant.

Typical anionic surfactants include but are not limited to sodium lauryl sulfate, sodium laureth sulfate, sodium trideceth sulfate, ammonium lauryl sulphate, ammonium laureth sulphate, potassium laureth sulfate, sodium tridecyl benzene sulfonate, sodium dodecyl benzene sulfonate, sodium xylene sulfonate, monoethanolamine lauryl sulfate, monoethanolamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, lauryl sarcosine, cocoyl sarcosine, sodium lauryl sarcosinate, sodium lauroyl sarcosinate, triethylamine lauryl sulfate, triethylamine laureth sulfate, diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauric monoglyceride sodium sulfate, ammonium cocoyl sulfate, ammonium lauroyl sulfate, sodium cocoyl sulfate, sodium lauroyl sulfate, sodium cocoyl isethionate, potassium cocoyl sulfate, potassium lauryl sulfate, monoethanolamine cocoyl sulfate, monoetha nolamine lauryl sulfate, triethanolamine lauryl sulfate, sodium hydroxyethyl-<NUM>-decyl ether sulfates, sodium methyl-<NUM>-hydroxydecyl ether sulfates, sodium hydroxyethyl-<NUM>-dodecyl ether sulfates, sodium monoethoxylated lauryl alkyl sulfates, C<NUM>-C<NUM> alkyl sulfonates, ethoxylated or native linear and ramified C<NUM>-C<NUM> alcohol sulfates, ethoxylated or native linear and ramified C<NUM>-C<NUM> alcohol sulfates, and mixtures thereof.

The role of the anionic surfactant according to the present invention is not only to act as cleaning agent, but also to assist the deposition of free chitosan onto the keratinous substate. Without being bound by theory, anionic surfactants are assumed to form complexes with chitosan which show better adherence on the substrate.

In advantageous embodiments of the invention, the anionic surfactant is selected from the group consisting of fatty acid sulphates, laureth sulphates, sarcosines and sarcosinates. The advantages of these particular anionic surfactants lie in theirof cleaning power.

The shell of the microcapsules may comprise shell-forming materials selected from the group consiting of inorganic materials, such as silicate, metals and metal oxides, or organic materials, such as surfactants, natural, semi-synthetic and synthetic organic polymers, and mixtures thereof. Particularly suitable are shells comprising silicates, gelatin, gelatin/gum arabicum complexes, gelatin/carboxymethyl cellulose complexes, alginate/calcium complexes, surfactant lamellar phases, and thermosetting resins, such as aminoplast resins, polyurea resins, polyurethane resins and polyacrylatre resins, and mixtures thereof. Microcapsules having shells comprising such thermosetting resin are particularly resistant to leakage of the uncapsulated functional material over time, while still providing optimal frangibility and release of the functional material when submitted to mechanical stresses.

In other advantageous embodiments of the invention, the consumer product comprises from <NUM>. 01to <NUM> wt. -%, more particularly from <NUM>. 1to <NUM> wt. -%, still more particularly from <NUM> to <NUM> wt. -% of microcapsules, referred to the total weight of the consumer product.

In other advantageous embodiments of the invention, the consumer product comprises from <NUM> to <NUM> wt. -%, more particularly from <NUM> to <NUM> wt. -%, still more particularly from <NUM> to <NUM> wt. -% of free chitosan, referred to the total weight of the consumer product.

The presence of free chitosan in a product can be recognized by the onset of filament-like structures that are visible under a conventional light microscope, operating under transmitted light and bright field conditions and with a magification of <NUM> to <NUM>. The typical section of such filament is typically between about <NUM> micrometres and about <NUM> micrometres and their length may be as large as <NUM> and more. Without being bound by any theory, the applicant believes that the formation of these filament-like structures is the result of chitosan complexation with anionic surfactants present in the product.

Typical consumer products concerned by the present invention include personal care cleaning and cleansing compositions, such as shampoos, bath and shower gels and liquid soaps.

In other advantageous embodiments of the present invention, the pH of the consumer product is from <NUM> to <NUM>, more particularly from <NUM> to <NUM>, and still more particularly from <NUM> to <NUM>. Such pH conditions provide optimal stability of the system comprising the dispersing medium, the coated microcapsules and the free chitosan.

Typical formulations of ingredients for use in shampoo with microcapsules according to the present invention may be found, for example, in <CIT> or <CIT>.

The microcapsules are preferably at a level of <NUM> to <NUM> wt. -%, more particularly from <NUM> to <NUM> wt. -% and still more particularly from <NUM> to <NUM> wt. -% of the personal care product, referred to the total weight of the shampoo composition.

In another embodiment of the present invention, the consumer product is a liquid soap comprising one or more anionic surfactants, and other surfactants that may be selected from the group consisting of aminoxide surfactants, non-ionic surfactants, zwitterionic surfactants, and mixtures thereof, mixtures of fatty acids and neutralized fatty acids, electrolytes, one or more preservative, and optionally benefit agents that may be selected from the group consisting of pH-control agents, skin care agents, moisturizers, emollients, thickeners, vitamins, nutrients and dyes.

Typical formulations of ingredients for use in liquid soaps may be found, for example, in <CIT> or <CIT>.

In another embodiment of the present invention, the consumer product is a shower gel comprising one or more anionic surfactant, and other surfactantsthat may be selected from the group consisting of mixtures of fatty acids and neutralized fatty acids, aminoxide surfactants, non-ionic surfactants, zwitterionic surfactants, aminoxide surfactants, aminoxide surfactants, and mixtures thereof, electrolytes, one or more preservative, and optionally benefit agents that may be selected from the group consisting of thickeners, pH-control agents skin care agents, moisturizers, emollients, thickeners, vitamins, nutrients, dyes, and the like.

Typical formulations of ingredients for use in shower gels may be found, for example, in <CIT> or <CIT>.

A broad selection of functional materials may be employed in connection with the present invention. The core of the capsules may in particular comprise a hydrophobic material selected from the group consisting of perfume materials, oils, essential oils, fragrance oils, biocides, pheromones, cosmetic materials and topical drugs.

The perfume materials and cosmetic materials to be encapsulated in the encapsulated compositions are preferably hydrophobic. Preferably, the cosmetic materials have a calculated octanol/water partition coefficient (ClogP) of <NUM> or more, more preferably <NUM> or more. Preferably, the ClogP of the cosmetic materials is from <NUM> to <NUM>.

Particularly useful cosmetic materials may be selected from the group consisting of emollients, smoothening actives, hydrating actives, soothing and relaxing actives, decorative actives, deodorants, anti-aging actives, draining actives, remodelling actives, skin levelling actives, preservatives, anti-oxidant actives, antibacterial or bacteriostatic actives, cleansing actives, lubricating actives, structuring actives, hair conditioning actives, whitening actives, texturing actives, softening actives, anti-dandruff actives, and exfoliating actives.

Particularly useful cosmetic materials include, but are not limited to, hydrophobic polymers, such as alkyldimethylsiloxanes, polymethylsilsesquioxanes, polyethylene, polyisobutylene, styrene-ethylene-styrene and styrene-butylene-styrene block copolymers, and the like, mineral oils, such as hydrogenated isoparaffins, silicone oils and the like, vegetable oils, such as argan oil, jojoba oil, aloe vera oil, and the like , fatty acids and fattyalcohols and their esters, glycolipide , phospholipides, sphingolipides, such as ceramides , sterols and steroids, terpenes, sesquiterpenes, triterpenes and their derivatives, essential oils, such as arnica oil, artemisia oil, bark tree oil, birch leaf oil, calendula oil, cinnamon oil, echinacea oil, eucalyptus oil, ginseng oil, jujube oil, helianthus oil, jasmine oil, lavender oil, lotus seed oil, perilla oil, rosmary oil, sandal wood oil, tea tree oil, thyme oil, valerian oil, wormwood oil, ylang ylang oil, yucca oil and the like.

In an embodiment of the present invention, the cosmetic material may be selected from the group consisting of sandal wood oil, such as fusanus spicatus kernel oil, panthenyl triacetate (<NPL>), tocopheryl acetate, tocopherol, naringinin (<NPL>), ethyl linoleate, farnesyl acetate, farnesol, citronellyl methyl crotonate (<NPL>), ceramide-<NUM> (<NUM>-stearoiyl-C18-sphingosine, <NPL>), and mixtures thereof.

The functional material may optionally be admixed with various hydrophobic excipients, such as apolar solvents, oils, waxes and apolar polymers.

Consumer products according to the present invention show improved micro-capsule deposition and rinse resistance on keratinous substrates, compared consumer products comprising polymer-coated microcapsules known to the art.

Once deposited on the keratinous surfaces, the microcapsules are able to release their functional material by diffusion through the microcapsule shell or following the mechanical rupture of the microcapsule shell. Mechanical rupture may follow a mechanical action, such as rubbing, squeezing, combing, washing and the like or heating, for example using a hair dryer.

Diffusion-mediated release is particularly desired if the functional material is a fragrance composition, because, in this case, a nice smell may be perceived over a long time, for example several hours, after application of the microcapsules on the substrate. On the other hand, a mechanical rupture may provoke a surprising and pleasant boost of odor.

In a second aspect of the present invention, there is provided a method for making a consumer product, in particular a consumer product as described herein above. The method comprises the steps of:.

In particularly advantageous embodiments of the invention, the consumer products may be formed according to a method comprising, preferably consisting of, the following steps:.

With regard to step b), the extent of coating may be expressed as the ratio of polymer weight added to the slurry to the weight of the encapulated functional material present in the slurry. The optimal chitosan coating to encapsulated functional material ratio may depend not only of the size and size distribution of the microcapsules, but also on the number of anionic groups present on the surface of the microcapsules and on the deacetylation grade of the chitosan, among other parameters. Hence, the optimal coating to microcapsules ratio may be different from case to case. For example, the optimal coating to encapsulated functional material ratio may vary from <NUM> to <NUM> and more, and have very diverse values such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The optimal coating to encapsulated functional material ratio is the point where substantially all cationic groups present on the chitosan molecules present in the slurry are bound to the microcapsules. This point coincides with the onset of a dark blue colour in the so-called ninhydrin colorimetric test. This test is based on the property of primary amines to react with ninhydrin (<NUM>,<NUM>-Dihydroxy-<NUM>-indene-<NUM>,<NUM>(<NUM>)-dione ,<NPL>) to form a dye known under the name of Ruhemann Violet (<NUM>-Hydroxy-<NUM>-[(<NUM>,<NUM>-dioxo-indanyliden-(<NUM>))-amino]-indenon-(<NUM>), <NPL>), according to a chemical mechanism known to the art (see for example <NPL>). The way the ninhydrine test is performed according to the present invention is described in Example <NUM> hereinunder.

Although adding to the slurry one more of a suspending agent, a preservative or any other conventional excipients is optional, it is conventional to stabilize a slurry by adding certain well-known excipients.

For example, once the slurry is formed, one can add a suspending agent to it in order to prevent the slurry from phase-separating, such as creaming or sedimenting. Any of the conventional suspending agents may be employed in the present invention. Coventional suspending agents include but are not limited to a hydrocolloid selected from the group consisting of starch and starch derivatives, such as modified starch, dextrin, maltodextrin, gums, such as gum arabic or gum accacia, xanthan gum, gum tragacanth, gum karaya, guar gum, cellulose and cellulose derivatives, such as carboxy methyl cellulose, hydroxyethyl cellulose, hydroxyethyl cellulose/lauryl-dimethylammoniumepoxy condensat, hydroxypopyl cellulose, cationic cellulose (for example polyquaternium-<NUM>), cellulose gum, carrageenan, agar-agar, pectines and pectic acid, gelatine, protein hydrolysates, polymer and copolymers of vinyl and allyl monomers, such as polyvinylpyrrolidone, poly(vinyl pyrrolidone-co-vinylacetate), poly(vinyl alcohol-co-vinyl acetate) (more particularly hydrolyzed polyvinylacetates having a degree of hydrolysis between <NUM> and <NUM>%), vinyl ester homopolymers and copolymers, such as vinyl acetate, vinyl pivalate, vinyl versatate, poly(vinyl methyl ether), poly(vinyl alkyl amines), such as poylvinylmethylamine, quaternized polyvinyl alkyl amines, vinyl pyridine and quaternized vinyl pyridine, vinyl imidazoline, vinyl imidazole, vinyl imidazolinium, dimethyldiallyl ammonium chloride, vinyl sulphonate homopolymers and/or copolymers, polyamines and polyimines, ethoxylated polyamines, polymers, copolymers and cross-polymers derived from (meth)acryloyl monomers, such as methyl methyl acrylate, ethyl methacrylate, <NUM>-ethyl-hexyl acrylate, lauryl methacrylate, C<NUM>-C<NUM> alkyl acrylate, hydroxyalkyl (meth)acrylate, such as <NUM>-hydroxypropyl acrylate and <NUM>-hydroxypropyl methacrylate, acrylamidodimethyl taurate, aryl (meth)acrylates, such as phenyl acrylate and benzyl acrylate, (meth)acrylic acids and their salts, such as sodium and potassium (meth)acrylates, sodium acryloyldimethyltaurate, (meth)acrylamides, N-alkyl (meth)acrylamides, such as N,N-dimethylaminoalkyl methacrylate, quaternized N-alkyl (meth)acrylamides, such as methacrylamidopropyl-trimethylammonium chloride, acrylamidoe-thyltrimonium chloride, acrylamidolauryltrimethylammonium chloride, and (meth)acrylamido alkyl sulphonates poly(maleic anhydride) and poly(maleic anhydride-co-vinyl ether), and their hydrolysates, poly(acrylic acid-co-maleic acid)copolymer, poly(alkyleneoxide), polyurethanes and polyureas, such as anionic, cationic non-ionic and amphoteric polyurethanes and polyureas, mixed copolymers thereof, and mixture thereof.

It isalso conventional to add biological preservatives to aqueous slurries to prevent unwanted growth of moulds and other microorganisms.

Suitable preservatives include, but are no limited to quaternary compounds, biguanide compounds (<NPL>, <NUM>-<NUM>-<NUM>, <NUM>-<NUM>-<NUM>, <NUM>-<NUM>-<NUM>), poylaminopropyl biguanidine, hexetidine, para-chloro-meta-cresol, methenamine, <NUM>-bis(hydroxymethyl)-<NUM>,<NUM>-dimethylimidazolidine-<NUM>,<NUM>-dione, quaternium-<NUM>, benzoic acid, salicylic acid, undec-<NUM>-enoic acid, formic acid, biphenyl-<NUM>-ol and their salts, <NUM>-hydroxybenzoic acid and its esters and salts, sorbic acid and its salts, isothiazolinones, <NUM>-bromo-<NUM>-nitro-<NUM>,<NUM>-propanediol, <NUM>-bromo-<NUM>-nitro-<NUM>,<NUM>-dioxane, <NUM>-(thiazol-<NUM>-yl) benzimidazole, benzimidazole carbamate, <NUM>-(<NUM>-ohlorophenyl)-<NUM>-(<NUM>,<NUM>-dichlorophenyl)uree, <NUM>-iodo-<NUM>-propynylbutylcarbamate, ethyl(<NUM>-mercaptobenzoato-(<NUM>-)-O,S) mercurate(<NUM>-) sodium, <NUM>-chloro-<NUM>-(<NUM>,<NUM>-dichlorophénoxy)phenol, dichlorobenzyl alcohol, chloroxylenol, imidazolidinyl urea, phenoxyethanol, benzyl alcohol and mixtures thereof.

In advantageous embodiments of the invention, chitosan is used as biological preservative and the slurry is substantially free of any additional biological preservative.

The slurry may also contain commonly employed adjuvants. The term "adjuvants" refers to ingredients that may affect the performance of a composition, other than its hedonic performance. For example, an adjuvant may be an ingredient that acts as an aid to processing a perfume composition or consumer product containing said composition, or it may improve handling or storage of a perfume composition or consumer product. It might also be an ingredient that provides additional benefits such as imparting colour or texture. It might also be an ingredient that imparts light resistance or chemical stability to one or more ingredients contained in a perfume composition or consumer product. A detailed description of the nature and type of adjuvants commonly used in perfume compositions or consumer products cannot be exhaustive, but such ingredients are well known to a person skilled in the art. Examples of adjuvants include solvents, waxes, oils, pigments, dyestuffs and colouring matters, extenders, fillers and reinforcing agents, stabilizers against the detrimental effects of heat and light, bulking agents, acidulants, buffering agents and antioxidants.

Compositions in the form of a slurry of core-shell microcapsules can be incorporated into all manner of consumer products. However, for some applications it might be desirable to add the core-shell microcapsules in the form of a dry powder. Thus, in accordance with the present invention, in an optional step for dehydrating the slurry to form a composition of core-shell microcapsules in powder form, the slurry may be dehydrated to provide the composition of the present invention in dry powder form.

If desired, the microcapsules can be isolated in the form of a dry powder. For example, the solid capsules can be isolated by filtration and dryed. Drying of the isolated capsules may be performed by heating, e.g. in an oven or by contact with a heated gas stream. Preferably, drying of the dispersion is carried out by spray drying or fluid-bed drying. Spray drying techniques and apparatus are well known in the art. A spray-drying process pushes suspended capsules through a nozzle and into a drying chamber. The capsules may be entrained in a fluid (such as air) that moves inside of a drying chamber. The fluid (which may be heated, for example at a temperature of <NUM> and <NUM>, more preferably between <NUM> °Cand <NUM>, and still more preferably between <NUM> and <NUM>) causes the liquid to evaporate, leaving behind the dried capsules which can then be collected from the process equipment and further processed.

Prior to or after the spray drying step, it may be desirable to add a flow aid, such as silica or the like to the slurry to ensure the realization of fine, free-flowing powdered microcapsules with low surface perfume oil. Flow aids include silicas or silicates, such as precipitated, fumed or colloidal silicas, starches, calcium carbonate, sodium sulphate, modified cellulose, zeolites or other inorganic particulates known in the art.

The slurry of microcapsules may be spray-dried in a conventional spray drying tower, using a two-fluid nozzle or spin-dried in a conventional spin dryer. If desired, at least one hydrocolloid may be added to the microcapsule slurry, as such or in the form of an aqueous solution. Typical hydrocolloids include starch, modified starch such as dextrin-modified with octenyl succinate anhydride, and gum arabic. Optionally, maltodextrins and sugar alcohols, such as sorbitol, mannitol or maltitol may also be added. The hydrocolloid may itself contain a functional material. This functional material may be the same as, or different form, that the functional material present in the core of the capsule. This is achieved by performing the step of (<NUM>) emulsifying a second functional material in aqueous hydrocolloid solution, optionally comprising maltodextrins and sugars or sugar alcohols to form a second slurry (<NUM>) mixing the second slurry with a slurry of microcapsules comprising a first functional material and (<NUM>) drying this mixture. Such a process is described in <CIT>, Example <NUM>.

By means of the present invention it is possible to obtain compositions in the form of a slurry of core-shell microcapsules that have a high core content, typically within the range of <NUM> to <NUM> wt %, and more particularly from <NUM> to <NUM> wt %.

A method for enhancing the deposition and rinse resistance of a plurality of microcapsules dispersed in a dispersing medium, in particular contained in a consumer product, on a surface, in particular on a keratinous surface is also disclosed. The microcapsules comprise a core and a shell around the core. The core comprise at least one functional material.

In another aspect of the invention, there is provided a use of chitosan for enhancing the deposition and rinse resistance of a plurality of microcapsules on a surface, in particular on a keratinous surface. The microcapsules comprise a core and a shell around the core. The core comprises at least one functional material. The microcapsules are dispersed in a dispersing medium, in particular contained in a consumer product. The use involves coating the plurality of microcapsules with chitosan toobtain a plurality of coated microcapsules and adding additional free chitosan to the dispersing medium. The use can be part of an above-described method.

Further advantages and particular features of the present invention become apparent from the following discussion of several examples.

Aminoplast microcapsules encapsulating a core comprising a fragrance material as functional material were prepared according to the method disclosed as process P5. <NUM> in <CIT>. The volume average diameter of the microcapsules, as measured by light scattering, was <NUM> ± <NUM> micrometres. The solid content of the slurry was <NUM> wt%, which corresponds to <NUM> wt% encapsulated perfume.

These microcapsules were coated with chitosan C1 by performing the steps of:.

This procedure was repeated with different a mounts of chitosan C1, so that the ratio chitosan C1 content to functional material content of the slurry (referred to as chitosan to functional material ratio hereinafter) was varied from <NUM> to <NUM> [samples <NUM> to <NUM>]. This ratio is used here for the sake of simplicity, considering that the functional material is almost quantitatively encapsulated and therefore varies linearly with the weight of the formed microcapsules.

Samples <NUM> to <NUM> were ultracentrifuged and the pH of their supernatant increased to <NUM> by adding NaOH. Then, <NUM> of a <NUM> wt% of ninhydrin in deionized water were admixed with <NUM> of supernatant. The development of a velvet color in the mixture is the sign of the presence of free unprotonated amine functional groups and therefore of the presence of free chitosan in the supernatant. On the other hand, the presence of free chitosan in the supernatant is a sign that the surface of the microcapsules is saturated by adsorbed chitosan and fully coated. The onset of the ninhydrin-amine complex can be taken as the point where the optimal chitosan to functional material ratio for quantitative coating has been exceeded. The optimal chitosan to functional material ratio is almost independent of the source, molecular weight and deacetylation grade of chitosan C1 (Table <NUM>). Oppositely, the zeta potential at pH <NUM> depends on these parameters (see Table <NUM>). It is also observed that the value of the zeta potential reaches a plateau once the quantitative coating has been reached, which confirms that the surface of the capsules is effectively saturated with chitosan C1. The value of the zeta potential at plateau is given in Table <NUM> for the different types of chitosan.

In a first set of experiments, chitosan C1-coated microcapsule slurries were added to a shampoo composition under gentle stirring with a paddle mixer (example <NUM> and <NUM> in table <NUM>).

In a second set of experiments, <NUM> of a <NUM>% chitosan C2 solution in deionized water at pH <NUM> were incorporated into <NUM> of shampoo base under gentle stirring with a propeller and dispersed therein under stirring. Then chitosan C1-coated microcapsule slurries were added under stirring, so that the level of slurry in the shampoo base was <NUM> wt% referred to the total weight of the shampoo base. The characteristics of both chitosan C2 and chitosan C1-coated microcapsule were varied. The mixture was let to macerate overnight before performing the deposition measurements.

In a fourth set of experiments, comparative samples were prepared with uncoated microcapsules and cationic guars instead of chitosan C2.

The shampoo was applied on swatches that have been previously wetted with tap water at a temperature of <NUM>. The amount of shampoo was <NUM>% of the weight of the swatches. The shampoo application was performed by gently massaging the swatches during <NUM> seconds, waiting for <NUM> minute, rinsing the swatches with tap water at a temperature of <NUM> °Cand removing the excess water by sliding each swatch between two fingers vertically from top to bottom. The extent of deposition was determined by image analysis micrographs obtained with a fluorescence light microscope at a magnification of <NUM> x, using Stream Motion software and Hostasol Yellow <NUM> as fluorescent agent at <NUM> wt% in perfume, <NUM> excitation wavelength and <NUM> emission wavelength. The deposition value and shampoo composition details are reported in Table <NUM>.

In Table <NUM>, the deposition scores obtained by a combination of chitosan-coated microcapsules and free chitosan, using chitosan with different molecular weights and origins, are compared to the scores obtained with un-coated microcapsules, with cationic microcapsules, with different free cationic polymer (cationic guar) and in the absence of of free chitosan.

Claim 1:
A consumer product comprising a plurality of microcapsules dispersed in a dispersing medium, the microcapsules comprising a core and a shell around the core, the core comprising at least one functional material, wherein the shells of the microcapsules are coated with chitosan and wherein the dispersing medium comprises additional free chitosan, wherein the chitosan that is coating the shells of the microcapsules and the free chitosan comprised in the dispersing medium have different average molecular weights.