WO2002000178A1

WO2002000178A1 - Compositions containing a metal pyrithione

Info

Publication number: WO2002000178A1
Application number: PCT/EP2001/006740
Authority: WO
Original assignee: Unilever Plc; Unilever Nv; Hindustan Lever Limited; Bailey, Peter, Lawrence; Jones, Margaret, Ann; Khoshdel, Ezat
Priority date: 2000-06-27
Filing date: 2001-06-12
Publication date: 2002-01-03
Also published as: GB0015723D0; AU6396101A

Abstract

Compositions comprising an insoluble metal pyrithione, such as zinc pyrithione, in an unstable crystalline form and one or more surfactants, may be stabilised by the inclusion in the composition of at least 0.001 % by weight of the composition of a nonionic, zwitterionic, cationic or anionic polymer which comprises a plurality of carbocyclic or heterocyclic, aromatic or non-aromatic rings.

Description

COMPOSITIONS CONTAINING A METAL PYRITHIONE

Field of the Invention

This invention relates to compositions comprising a metal pyrithione and a surfactant. In particular, the invention involves hair treatment compositions, such as shampoos, and methods of treating hair using the compositions.

Background and Prior Art

Insoluble particulate metal pyrithiones are acknowledged as antimicrobial agents which can be incorporated into antimicrobial compositions, such as antidandruff hair shampoos and conditioners. The zinc salt, zinc pyrithione (also referred herein as ZnPTO and ZPT) is widely used in this context. Generally, dispersed particles of ZnPTO are suspended in the composition which is then applied to the hair to deposit the ZnPTO on the hair and scalp.

Zinc pyrithione can be used in antidandruff compositions in a number of different particulate forms. The different particulate forms of ZnPTO can each impart different properties to the compositions.

In order to overcome certain disadvantages over the conventional forms of irregularly shaped ZnPTO particles, a number of crystalline forms of the compound have been described. For example, EP-A-0034385 describes an anti- dandruff hair care composition comprising flat, platelet shaped ZnPTO crystals. Also, JP-A-8283243 describes a mica- like shaped l-hydroxy-2-pyridinethione (ie, pyrithione) heavy metal salt for use in hair compositions.

A particularly advantageous particulate form of metal pyrithione is the needle-shaped form described in 099/66886. Hair treatment compositions comprising the particles combine the desirable properties of efficiency against dandruff, stability and aesthetic appeal.

The needle-shaped metal pyrithione particles described in 099/66886 are generally substantially stable at 50°C in the form in which they are supplied. However, when the particles are formulated together with a surfactant, for example in a formulated shampoo composition, they are found to be thermally unstable at 50°C, degrading to platelet-like particles in less than a week and thereby causing the composition to lose the advantages of needle-shaped particles relative to platelet-like particles, such as pearlescence in the shampoo.

An antimicrobial hair treatment composition is described in WO 97/03637 comprising at least one surfactant, a specified size range of insoluble particulate metal pyrithione and a cationic deposition aid. There is, however, no disclosure of an unstable crystalline form of an insoluble metal pyrithione in WO 97/03637 or of how any instability problem might be solved.

Antidandruff shampoo compositions have also been disclosed in the following documents: US 4,830,774, which comprises specified amounts of particulate antidandruff agent, a water insoluble suspending agent and a cross-linked ethylene maleic anhydride resin; JP 54041909, comprising a specified ampholytic high polymer, cationic cellulose ether, a water- insoluble solid fine particulate material and preferably an anionic surfactant; JP 030184907, comprising a specified dimethylpolysiloxane, l-hydroxy-2-pyrrolidone based compound and a water insoluble polymer compound; and JP 080012535, comprising sodium polyoxyethylenelauryl ether sulfate (3EO) , lauric acid diethanolamide, cellulose trimethylammonium salt and zinc pyrithione. None of these documents, however, discloses the presence of an insoluble metal pyrithione in an unstable crystalline form or methods of dealing with the instability of such products.

It is the aim of the present invention to provide compositions comprising a metal pyrithione, and also containing a surfactant, which are more stable, in terms of the particulate form of the metal pyrithione, than the compositions of the prior art.

Statement of the Invention

According to the present invention in a first aspect, there is provided a composition comprising an insoluble metal pyrithione in an unstable crystalline form, from 5 to 30% by weight of the composition of one or more surfactants and at least 0.001% by weight of the composition of a nonionic or anionic polymer which comprises a plurality of optionally substituted rings selected from phenyl, naphthyl, nitrogen- containing unsaturated heterocycles and mixtures thereof. In another aspect, the invention provides a method of treating hair which comprises applying to the hair a composition of the invention.

A further aspect of the invention is the use of a composition of the invention in the manufacture of a medicament for the treatment of dandruff.

A still further aspect of the invention provides the use of a polymer which is nonionic, anionic, cationic or zwitterionic and which comprises a plurality of carbocyclic or heterocyclic, aromatic or non-aromatic rings as a stabilising agent for zinc pyrithione in a composition comprising zinc pyrithione in an unstable crystalline form and a surfactant.

Detailed Description of the Invention

The present invention is based on the finding that insoluble metal pyrithione particles, particularly those in an unstable crystalline form, are destabilised in the presence of a surfactant. The invention is also based on the finding that the problem of instability of the metal pyrithione particles in the presence of a surfactant can be overcome by the use, as a stabilising agent for increasing the stability of the metal pyrithione particles, of a polymer which comprises a plurality of carbocyclic or heterocyclic, aromatic or non-aromatic rings.

The insoluble metal pyrithione may be represented by the following general formula:

in which M is a polyvalent metal ion and n corresponds to the valency of M.

Preferred examples of M include magnesium, barium, strontium, zinc, cadmium, tin and zirconium. Especially preferred is zinc.

The insoluble metal pyrithione may be made up of one particulate form or two or more different particulate forms, One or more of the particulate forms will generally be unstable in the presence of a surfactant with respect to other forms of the compound, in the absence of the stabilising agent used in the invention.

The term unstable means that the crystalline form would convert at least partially (and preferably substantially completely) to another form of the metal pyrithione, in the same composition comprising the surfactant but without the stabilising agent, in a time of up to six months, preferably from 1 day to six months.

The insoluble metal pyrithione preferably comprises needle- shaped particles. The needle-shaped particles are preferably of the type described in W099/66886, the contents of which are incorporated herein by reference. Thus, preferably at least 50% by number of the particles are needle-shaped particles having a length of between Iμm and 50μm.

The term needle-shaped particle and like terms used herein is used to describe a generally elongate three-dimensional particle of any transverse cross-sectional shape, the particle having one dimension, its length, substantially greater than the other two. By substantially is meant greater by a factor of at least two, preferably at least 3 and most preferably at least 5. Although the cross- sectional shape of the particle is not critical, it is typically polygonal.

The needle-shaped particles of metal pyrithione preferably have a size distribution in which at least about 50% of the particles, by number of the particles, have a length of between 1 and 50 μm. Preferably, the size distribution is such that at least about 50% of the particles, by number of the particles, have a length of between 2 and 40 μm; most preferably between 4 and 30 μm and even more preferably between 5 and 15 μm; the most preferred length being between 10 and 15 μm. In an even more preferred embodiment, the size distribution is such that at least about 70% of the particles, by number of the particles, have a length of between 2 and 40 μm; most preferably between 4 and 30 μm and even more preferably between 5 and 15μm; the most preferred length is between 10 and 15 μm. In the most preferred embodiment, the size distribution is such that at least about 80% of the particles, by number of the particles, have a length of between 2 and 40 μm; most preferably between 4 and 30 μm, and even more preferably between 5 and 15 μm; the most preferred length being between 10 and 15 μm. The dimensions of the needle-shaped particles can be determined most conveniently visually using an electron microscope.

The amount of metal pyrithione incorporated into the compositions of the invention may depend on the type of composition and the exact nature of the material used. A preferred amount of pyrithione is from about 0.001 to about 5% by weight of the total composition, more preferably from about 0.05 to about 3% by weight, most preferably between 0.1 and 1%.

The preparation of the needle-shaped particles is described in W099/66886.

The polymer which is used in the invention, principally to stabilise the unstable crystalline form of the insoluble metal pyrithione, although it may also have other functions, is a nonionic, zwitterionic or anionic polymer which comprises a plurality of carbocyclic or heterocyclic, aromatic or non-aromatic rings. Cationic polymers may also be used in the invention as stabilising agents. The polymer may be a single polymer or a mixture of different polymers. Each polymer chain will typically contain a single type of ring system. However, at least some of the polymer chains may comprise two or more different ring systems. The polymers typically contain more than ten rings per polymer chain, preferably more than twenty rings, more preferably more than 50 rings.

The rings may be present in the polymer as an integral part of the polymer backbone or they may be bound to the polymer backbone, either by being bound by direct covalent bonds or by being bound by way of covalent linker groups (such as Ci- Cβ alkylene groups eg, methylene) . Without wishing to be bound by theory, it is believed that the rings interact with the surface of the metal pyrithione particles to form a protective barrier which inhibits their conversion to other particle forms.

The polymer may be a homopolymer or a copolymer. When the polymer is a copolymer, it may be formed from one or more monomers each containing a ring system and, optionally, one or more monomers which do not contain a ring system. Therefore, the rings in the polymer may be provided either by the residues of one monomer or by the residues of two or more different monomers.

The polymers or copolymers used in the present invention may possess any of the well-known polymer structures or architectures or mixtures thereof. Thus, the copolymers useful in the present invention may possess, for example, the structures commonly referred to as random (ie, the repeat units are dispersed randomly along linear chains) , block (ie, a linear arrangement of blocks of the different repeat units) , graft (ie, one or more species of side-chain block differing from the main chain are connected to a main chain) , alternating (ie, a regular copolymer in which the repeat units are arranged in an alternating sequence (AB) _n) , or hyperbranched. Alternatively, the polymers or copolymers of the present invention may possess stereoregular linear structures, as defined by International Union of Pure and Applied Chemistry, or cross-linked structures (ie, where chains of the polymer are joined together to form a three- dimensional network) . The possible polymer structures or architectures are further defined in the Concise Encyclopedia of Polymer Science (Executive Editor J I Kroschwitz, Published by John Wiley & Sons, 1990) .

Ring systems may be carbocyclic or heterocyclic, aromatic or non-aromatic. Carbocyclic, aromatic rings include monocyclic systems (eg, phenyl or phenylene groups) and fused bicyclic systems (eg, naphthyl or naphthylene groups) and substituted derivatives thereof. The ring groups will be monovalent (eg, phenyl) if they are bound to the polymer backbone or divalent (eg, phenylene) if they form an integral part of the polymer backbone. Carbocyclic, non- aromatic rings include, for example, C3 to C₆ alkyl or alkylene and C5 to C& alkenyl or alkenylene groups eg, cyclohexyl or cyclohexylene, cyclopentyl or cyclopentylene, cyclohexenyl or cyclohexenylene and cyclopentenyl or cyclopentenylene, and bicyclic systems, eg, norbornyl and norbornylene and substituted derivatives thereof. Substituents include one or more C_± to Cβ alkyl groups, keto groups bound to atoms on the ring and polar groups such as - SO3H, -C0₂H and their corresponding deprotonated anions. Heterocyclic rings include four, five and six membered rings containing from 1 to 3 atoms selected from S, 0, N and mixtures thereof. Aromatic unsaturated heterocyclic rings include pyridinyl, pyridinylene, pyrrolyl, pyrrolylene, thiophenyl, thiophenylene, furanyl and furanylene. Non- aromatic, heterocyclic rings include piperidyl, piperidylene, piperidinyl, piperidinylene, pyrrolidinyl and pyrrolidinylene. Heterocyclic rings may be substituted with, for example, one or more Ci to C₆ alkyl groups, keto groups bound to atoms on the ring and polar groups such as - SO₃H, -C0₂H and their corresponding deprotonated anions. The rings are preferably not saccharides.

Preferred polymers that incorporate rings in the backbone (or main chain) of the polymer (the terms main chain and backbone are used synonymously herein) include, for example, polyesters, polycarbonates, polyamides, polyureas and epoxy resins; such polymers can be produced by a number of routes which are well-known in the art including, for example, step growth polymerisation or polycondensation. Specific materials include polyethylene terephthalates containing nonionic, hydrophilic polyethylene glycol groups such as Permalose™ (available from ICI Chemicals) or anionic (sulphonate) groups such as Luviset PUR™ (available from BASF) .

Preferred polymers which contain rings bound to the polymer backbone (ie, as side groups) include, for example, homo- and copolymers of monomers of the vinyllactam family, such as poly (vinyl pyrrolidone) , poly (vinyl caprolactam) , polyvinyl (pyrrolidone-co-vinyl acetate) , poly (vinyl pyrrolidone-co-vinyl alcohol) , poly (vinyl pyrrolidone-co- vinyl imidazole) , poly (vinyl pyridine) , poly (vinyl pyridine N-oxide) , poly (vinyl pyridine sulphobetaine) and poly (vinyl pyridine betaine) . Polymers of this type can be produced by conventional methods and are available, for example, from BASF or ISP. The polymers are typically produced by chain growth polymerisation ie, cationic, anionic or radical polymerisation (with the latter technique being preferred) .

Therefore, preferred polymers comprise in the backbone (or main chain) one or more groups of formula (I) :

(I)

wherein R comprises a ring and , optionally, a linker group between the polymer main chain and the ring, and is, for example:

wherein x is an integer from 1 to 6 (preferably 1 to 3) and Y is an anionic group (preferably -C0₂ ^~ or -S0₃ ^") and/or one or more groups of formula (II)

(II)

wherein A comprises a ring system, and A is, for example:

wherein B is a substitutent on the ring and is preferably an anionic group such as -C0₂ ^~ or -S0₃ ^~.

When the polymer of the invention is a copolymer, the polymer chain may comprise units derived from monomers which do not contain a ring. Suitable non-ring groups in the polymer include, for example, groups derived from the monomers vinyl acetate, vinyl alcohol, Ci to β alkyl methacrylates, Ci to C₆ alkyl acrylates, acrylic acid, methacrylic acid, ethylene glycol, formaldehyde and cyclohexane-dimethanol. The term Ci to Cβ alkyl covers branched and straight chain alkyl, and for C₃ to C₆ cycloalkyl, optionally substituted eg, with a dimethylamino group .

Polymers suitable for use in the invention include, for instance, poly (vinylpyrrolidone-co-ethyl methacrylate-co- methacrylic acid) (eg, Stephan Hold 1™ from Stephan) , poly

(vinylpyrrolidone-co-dimethylaminoethyl methacrylate) (eg, Styleze CC-10™ from ISP) , poly (vinyl caprolactam-co-vinyl pyrrolidone-co-dimethylaminoethyl methacrylate) (eg, Aquaflex Sf-40™ or H20LD EP-1™ from ISP) and poly

(isophthalic acid-co-diethylene glycol-co-5- sodiosulphoisophthalic acid-co-cyclohexanedimethanol) (eg, AQ48 Ultra™ from Eastman) .

It is preferable, but not essential, for at least a proportion of the rings in the polymer to bear one or more polar groups. Without wishing to be bound by theory, it is believed that the polar groups may induce dipole-dipole interactions with the metal pyrithione particles.

Preferably, at least a proportion of the rings in the polymer are substantially planar, more preferably all of the rings are substantially planar. By substantially planar, it is meant that at equilibrium the bonds to the carbon atoms or the heteroatoms in the ring do not deviate out of the plane of the ring by more than about 30°. Such rings are conventionally thought of by the skilled person as being flat or planar.

Preferred polymers for use in the invention include copolymers of an aldehyde, preferably formaldehyde, and a compound comprising an optionally substituted phenyl or naphthyl group. The optional substituent may be selected from, for example, one or more of the group consisting of: S0₃ ^", C0₂ ^", CN and N0₂, more preferably S0₃ ^~ or C0₂ ^".

Particularly preferred polymers for use in the invention include polysodium polynaphthalene sulphonic acid salts (ie, sodium polynaphthalene sulphonate, which is the term normally applied to the copolymer formed by cross-linking naphthalene sulphonate with formaldehyde) and polymers and copolymers of vinylpyrrolidine (e.g, l-vinyl-2-pyrrolidine) . Copolymers of vinylpyrrolidine include copolymers with vinyl acetate (optionally at least partially hydrolysed to remove the acetyl groups after polymerisation) . Where the polymer is a polymer derived from vinylpyrrolidine, the ratio of the amount of groups derived from vinylpyrrolidine to the amount of groups derived from other monomers is preferably in the molar ratio of from 90:10 to 20:80, more preferably 80:20 to 40:60.

The polymer used in the invention typically has a number average molecular weight of from 100 to 10,000,000 Da (preferably 10,000 to 50,000 Da) and/or a weight average molecular weight of from 200 to 4,000,000 Da (preferably 10,000 to 100,000 Da) .

The polymer is present in the composition in an amount of from 0.001% by weight of the composition. The precise amount of the polymer which is effective to stabilise a composition will depend on the exact nature of the particular composition. Preferably, however, the amount by weight of the polymer in the composition is from 0.01% to 10%, more preferably 0.01% to 3%, most preferably 0.05% to

The composition of the invention is preferably a hair treatment composition.

Hair treatment compositions of the present invention may be formulated as transparent or opaque emulsions, lotions, creams, pastes or gels. Particularly preferred product forms are shampoos and conditioners, especially shampoos.

Shampoo Compositions

A particular preferred hair treatment composition in accordance with the invention is a shampoo composition.

Such a shampoo composition will comprise, as the one or more surfactants, one or more cleansing surfactants which are cosmetically acceptable and suitable for topical application to the hair. Further surfactants may be present as an additional ingredient if sufficient for cleansing purposes is not provided as emulsifier for any emulsified components in the composition, eg, emulsified silicones. It is preferred that shampoo compositions of the invention comprise at least one further surfactant (in addition to that used as emulsifying agent) to provide a cleansing benefit.

Suitable cleansing surfactants, which may be used singularly or in combination, are selected from anionic, amphoteric and zwitterionic surfactants, and the mixtures thereof. The cleansing surfactant may be the same surfactant as the emulsifier, or may be different.

Examples of anionic surfactants are the alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates, N- alkyl sarcosinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates, and alpha-olefin sulphonates, especially their sodium, magnesium, ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups generally contain from 8 to 18 carbon atoms and may be unsaturated. The alkyl ether sulphates, alkyl ether phosphates and alkyl ether carboxylates may contain from 1 to 10 ethylene oxide or propylene oxide units per molecule.

Typical anionic surfactants for use in shampoos of the invention include sodium oleyl succinate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, sodium dodecylbenzene sulphonate, triethanolamine dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauryl isethionate and sodium N-lauryl sarcosinate. The most preferred anionic surfactants are sodium lauryl sulphate, triethanolamine monolauryl phosphate, sodium lauryl ether sulphate 1 EO, 2E0 and 3EO, ammonium lauryl sulphate and ammonium lauryl ether sulphate 1E0, 2EO and 3EO.

Examples of amphoteric and zwitterionic surfactants include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines) , alkyl glycinates, alkyl carboxyglycinates, alkyl amphopropionates, alkylamphoglycinates, alkyl amidopropyl hydroxysyltaines, acyl taurates and acyl glutamates, wherein the alkyl and acyl groups have from 8 to 19 carbon atoms. Typical amphoteric and zwitterionic surfactants for use in shampoos of the invention include lauryl amine oxide, cocodimethyl sulphopropyl betaine and preferably lauryl betaine, cocamidopropyl betaine and sodium cocamphopropionate.

The shampoo composition can also include co-surfactants, to help impart aesthetic, physical or cleansing properties to the composition. A preferred example is a nonionic surfactant, which can be included in an amount ranging from 0% to about 5% by weight of the total composition.

For example, representative nonionic surfactants that can be included in shampoo compositions of the invention include condensation products of aliphatic (C₈ - Ciβ) primary or secondary linear or branched chain alcohols or phenols with alkylene oxides, usually ethylene oxide and generally having from 6 to 30 ethylene oxide groups.

Other representative nonionics include mono- or di-alkyl alkanolamides. Examples include coco mono- or di- ethanolamide and coco mono-isopropanala ide.

Further nonionic surfactants which can be included in shampoo compositions of the invention are the alkyl polyglycosides (APGs) . Typically, the APG is one which comprises an alkyl group connected (optionally via a bridging group) to a block of one or more glycosyl groups. Preferred APGs are defined by the following formula: RO - ( G) π

wherein R is a branched or straight chain alkyl group which may be saturated or unsaturated and G is a saccharide group.

R may represent a mean alkyl chain length of from about C₅ to about C₂₀. Preferably R represents a mean alkyl chain length of from about Cs to about C_i2. Most preferably the value of R lies between about 9.5 and about 10.5. G may be selected from C₅ or C₆ monosaccharide residues, and is preferably a glucoside. G may be selected from the group comprising glucose, xylose, lactose, fructose, mannose and derivatives thereof. Preferably G is glucose.

The degree of polymerisation, n, may have a value of from about 1 to about 10 or more. Preferably, the value of n lies in the range of from about 1.1 to about 2. Most preferably the value of n lies in the range of from about 1.3 to about 1.5.

Suitable alkyl polyglycosides for use in the invention are commercially available and include for example those materials identified as: Oramix NS10™ ex Seppic; Plantaren 1200™ and Plantaren 2000™ ex Henkel.

The total amount of surfactant (including any co-surfactant, and/or any emulsifier) in shampoo compositions of the invention is from 5 to 30%, preferably from 10% to 25% by weight of the total shampoo composition. A cationic deposition polymer is a preferred ingredient in shampoo compositions of the invention, for enhancing conditioning performance of the shampoo. By deposition polymer is meant an agent which enhances deposition of the silicone component from the shampoo composition onto the intended site during use, ie, the hair and/or the scalp.

The deposition polymer may be a homopolymer or be formed from two or more types of monomers. The molecular weight of the polymer will generally be between 5,000 and 10,000,000 typically at least 10,000 and preferably in the range 100,000 to about 2,000,000. The polymers will have cationic nitrogen containing groups such as quaternary ammonium or protonated amino groups, or a mixture thereof.

The cationic nitrogen-containing group will generally be present as a substituent on a fraction of the total monomer units of the deposition polymer. Thus, when the polymer is not a homopolymer it can contain spacer non-cationic monomer units. Such polymers are described in the CTFA Cosmetic

Ingredient Directory, 3^rd edition. The ratio of the cationic to non-cationic monomer units is selected to give a polymer having a cationic charge density in the required range.

Suitable cationic deposition polymers include, for example, copolymers of vinyl monomers having cationic amine or quaternary ammonium functionalities with water soluble spacer monomers such as (meth) acrylamides, alkyl and dialkyl (meth) acrylamides, alkyl (meth) acrylate, vinyl caprolactone and vinyl pyrrolidine. The alkyl and dialkyl substituted monomers preferably have C1-C7 alkyl groups, more preferably Cl-3 alkyl groups. Other suitable spacers include vinyl esters, vinyl alcohol, maleic anhydride, propylene glycol and ethylene glycol.

The cationic amines can be primary, secondary or tertiary amines, depending upon the particular species and the pH of the composition. In general secondary and tertiary amines, especially tertiary, are preferred.

Amine substituted vinyl monomers and amines can be polymerized in the amine form and then converted to ammonium by quaternization.

The cationic deposition polymers can comprise mixtures of monomer units derived from amine- and/or quaternary ammonium-substituted monomer and/or compatible spacer monomers .

Suitable cationic deposition polymers include, for example:

- copolymers of l-vinyl-2-pyrrolidine and l-vinyl-3-methyl- imidazolium salt (eg chloride salt) , referred to in the industry by the Cosmetic, Toiletry, and Fragrance Association, (CTFA) as Polyquaternium-16. This material is commercially available from BASF Wyandotte Corp.

(Parsippany, NJ. USA) under the LUVIQUAT tradename (eg LUVIQUAT FX 370) ;

- copolymers of l-vinyl-2-pyrrolidine and dimethylaminoethyl methacrylate, referred to in the industry (CTFA) as

Polyqyaternium-11. This material is available commercially from Gaf Corporation (Wayne, NJ, USA) under the GAFQUAT tradename (eg GAFQUAT 755N) ;

- cationic diallyl quaternary ammonium containing polymers including, for example, dimethyldiallylammonium chloride homopolymer and copolymers of acrylamide and dimethyldiallylammonium chloride, referred to in the industry (CTFA) as Polyquaternium 6 and Polyquaternium 7, respectively;

- mineral acid salts of a ino-alkyl esters of homo-and copolymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms, (as described in U.S. Patent 4,009,256);

- cationic polyacrylamides (as described in W095/22311) .

Other cationic deposition polymers that can be used include cationic polysaccharide polymers, such as cationic cellulose derivatives, cationic starch derivatives, and cationic guar gum derivatives.

Cationic polysaccharide polymers suitable for use in compositions of the invention include those of the formula:

A-0-[R-N⁺(R^x) (R²) (R³) X^~] ,

wherein: A is an anhydroglucose residual group, such as a starch or cellulose anhydroglucose residual. R is an alkylene, oxyalkylene, polyoxyalkylene, or hydroxyalkylene group, or combination thereof. R¹, R² and R³ independently represent alkyl, aryl, alkylaryl, arylalkyl, alkoxyalkyl, or alkoxyaryl groups, each group containing up to about 18 carbon atoms. The total number of carbon atoms for each cationic moiety (i.e., the sum of carbon atoms in R¹, R² and R³) is preferably about 20 or less, and X is an anionic counterion.

Cationic cellulose is available from Amerchol Corp. (Edison, NJ, USA) in their Polymer JR (trade mark) and LR (trade mark) series of polymers, as salts of hydroxyethyl cellulose reacted with trimethyl ammonium substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 10. Another type of cationic cellulose includes the polymeric quaternary ammonium salts of hydroxyethyl cellulose reacted with lauryl dimethyl ammonium-substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 24. These materials are available from Amerchol Corp. (Edison, NJ, USA) under the tradename Polymer LM-200.

Other suitable cationic polysaccharide polymers include quaternary nitrogen-containing cellulose ethers (e.g. as described in U.S. Patent 3,962,418), and copolymers of etherified cellulose and starch (e.g. as described in U.S. Patent 3,958,581) .

A particularly suitable type of cationic polysaccharide polymer that can be used is a cationic guar gum derivative, such as guar hydroxypropyltrimonium chloride (Commercially available from Rhodia (formerly RhonePoulenc) in their JAGUAR trademark series) . Examples are JAGUAR C13S, which has a low degree of substitution of the cationic groups and high viscosity. JAGUAR C15, having a moderate degree of substitution and a low viscosity, JAGUAR C17 (high degree of substitution, high viscosity) , JAGUAR C16, which is a hydroxypropylated cationic guar derivative containing a low level of substituent groups as well as cationic quaternary ammonium groups, and JAGUAR 162 which is a high transparency, medium viscosity guar having a low degree of substitution.

Preferably the cationic deposition polymer is selected from cationic cellulose and cationic guar derivatives. Particularly preferred deposition polymers are JAGUAR C13S, JAGUAR C15, JAGUAR C17 and JAGUAR C16 and JAGUAR C162.

The cationic deposition polymer will generally be present at levels of from 0.001 to 5%, preferably from about 0.01 to 1%, more preferably from about 0.02% to about 0.5% by weight of the total composition. Solid Active Agents

Optional solid active agents include, in addition to the insoluble metal pyrithione particles, other antifungal agents such as climbazole, piroctone olamine, selenium sulphide and ketoconazole.

Other suitable solid active agents include pigment particles, such as solid dyes or colorants suitable for application to hair, and metal colloids. Aesthetic Agents

Hair treatment compositions such as shampoos and conditioners are frequently opacified or pearlised to enhance consumer appeal .

Examples of opacifying agents include higher fatty alcohols (e.g. cetyl, stearyl, arachidyl and behenyl) , solid esters (e.g. cetyl palmitate, glyceryl laurate, stearamide MEA- stearate) , high molecular weight fatty amides and alkanolamides and various fatty acid derivatives such as propylene glycol and polyethylene glycol esters. Inorganic materials used to opacify hair treatment compositions include magnesium aluminum silicate, zinc oxide, and titanium dioxide.

Pearlescing agents typically form thin, platelet-type crystals in the composition, which act like tiny mirrors. This gives the pearl lustre effect. Some of the opacifying agents listed above may also crystallise as pearlescing agents, depending on the media in which they are used and the conditions employed.

Typical pearlescing agents may be selected from C16-C22 fatty acids (e.g. stearic acid, myristic acid, oleic acid and behenic acid) , esters of C16-C22 fatty acid with alcohols and esters of C16-C22 fatty acid incorporating such elements as alkylene glycol units. Suitable alkylene glycol units may include ethylene glycol and propylene glycol. However, higher alkylene chain length glycols may be employed. Suitable higher alkylene chain length glycols include polyethylene glycol and polypropylene glycol.

Examples are polyethylene glycol mono or diesters of C16-C22 fatty acids having from 1 to 7 ethylene oxide units, and ethylene glycol esters of C16-C22 fatty acids. Preferred esters include polyethylene glycol distearates and ethylene glycol distearates. Examples of a polyethylene glycol distearate available commercially are EUPERLAN PK900™ (ex Henkel) or GENAPOL TS™ (ex Hoechst) . An example of an ethylene glycol distearate is EUPERLAN PK3000™ (ex Henkel) .

Other pearlescing agents include alkanolamides of fatty acids having from 16 to 22 carbon atoms, (e.g. stearic monoethanolamide, stearic diethanolamide, stearic monoisopropanolamide and stearic monoethanolamide stearate) ; long chain esters of long chain fatty acids (e.g. stearyl stearate, cetyl palmitate) ; glyceryl esters (e.g. glyceryl distearate) , long chain esters of long chain alkanolamides (e.g. stearamide DEA distearate, stearamide MEA stearate), and alkyl (C18C22) dimethyl amine oxides (e.g. stearyl dimethyl amine oxide) .

Further suitable pearlescing agents include inorganic materials such as nacreous pigments based on the natural mineral mica. An example is titanium dioxide coated mica. Particles of this material may vary in size from 2 to 150 microns in diameter. In general, smaller particles give rise to a pearly appearance, whereas particles having a larger average diameter will result in a glittery composition. Suitable titanium dioxide coated mica particles are those sold under the trade names TIMIRON (Merck) or FLAMENCO (Mearl) .

The level of opacifying or pearlescing agent employed in compositions of the invention is generally from 0.01 to 20%, preferably 0.01 to 5%, more preferably from 0.02 to 2% by weight of the total composition.

Gas (e.g. air) bubbles represent another type of suspended phase that may be introduced into a hair treatment composition for aesthetic purposes. When evenly sized and homogeneously dispersed in the composition, these can enhance consumer appeal - a typical application is in a transparent or translucent composition such as a hair styling gel.

Conditioners

Compositions which may be stabilised in accordance with the invention also include conditioners for the treatment of hair (typically after shampooing) and subsequent rinsing.

Such a conditioner will comprise one or more conditioning surfactants which are cosmetically acceptable and suitable for topical application to the hair.

Suitable conditioning surfactants are selected from cationic surfactants, used singly or in admixture. Examples include quaternary ammonium hydroxides or salts thereof, eg chlorides.

Suitable cationic surfactants for use in hair conditioners of the invention include cetyltrimethylammonium chloride, behenyltrimethylammonium chloride, cetylpyridinium chloride, tetramethylammoniu chloride, tetraethylammonium chloride, octyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octyldimethylbenzylammonium chloride, decyldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride, didodecyldimethylammonium chloride, dioctadecyldimethylammonium chloride, tallowtrimethylammonium chloride, cocotrimethylammonium chloride, and the corresponding hydroxides thereof. Further suitable cationic surfactants include those materials having the CTFA designations Quaternium-S, Quaternium-31 and Quaternium-18. Mixtures of any of the foregoing materials may also be suitable. A particularly useful cationic surfactant for use in hair conditioners of the invention is cetyltrimethylammonium chloride, available commercially, for example as GENAMIN CTAC™, ex Hoechst Celanese.

In conditioners of the invention, the level of cationic surfactant is preferably from 0.01 to 10%, more preferably 0.05 to 5%, most preferably 0.1 to 2% by weight of the composition.

Conditioners of the invention advantageously incorporate a fatty alcohol. The combined use of fatty alcohols and cationic surfactants in conditioning compositions is believed to be especially advantageous, because this leads to the formation of a lamellar phase, in which the cationic surfactant is dispersed.

Representative fatty alcohols comprise from 8 to 22 carbon atoms, more preferably 16 to 20. Examples of suitable fatty alcohols include cetyl alcohol, stearyl alcohol and mixtures thereof. The use of these materials is also advantageous in that they contribute to the overall conditioning properties of compositions of the invention.

The level of fatty alcohol in conditioners of the invention is conveniently from 0.01 to 10%, preferably from 0.1 to 5% by weight of the composition. The weight ratio of cationic surfactant to fatty alcohol is suitably from 10:1 to 1:10, preferably from 4:1 to 1:8, optimally from 1:1 to 1:4.

Conditioning Agents

The compositions which may be used in the invention may contain a conditioning agent. As used herein, the term conditioning agent includes any material which is used to give a particular conditioning benefit to hair and/or skin. For example, in compositions for use in washing hair, such as shampoos and conditioners, suitable materials are those which deliver one or more benefits relating to shine, softness, co bability, wet-handling, anti-static properties, protection against damage, body, volume, stylability and manageability. Preferred conditioning agents for use in the present invention include emulsified silicones, used to impart for example wet and dry conditioning benefits to hair such as softness, smooth feel and ease of combability.

Various methods of making emulsions of particles of silicones for use in the invention are available and are well known and documented in the art.

The viscosity of the silicone itself (not the emulsion or the final washing composition) preferably ranges from 10,000 cps to 5 million cps . The viscosity can be measured by means of a glass capillary viscometer as set out further in Dow Corning Corporate Test Method CTM004 July 20 1970.

Suitable silicones include polydiorganosiloxanes, in particular polydimethylsiloxanes which have the CTFA designation dimethicone. An example is dimethicone fluid having a viscosity of up to 100,000 centistokes at 25°C, which is available commercially from the General Electric

Company as the Viscasil™ series and from Dow Corning as the DC 200™ series.

Aminofunctional silicones which have the CTFA designation amodimethicone, are also suitable for use in the compositions of the invention, as are polydimethyl siloxanes having hydroxyl end groups, which have the CTFA designation dimethiconol .

Also suitable are silicone gums. "Silicone gum" denotes polydiorganosiloxanes having a molecular weight of from 200,000 to 1,000,000 and specific examples include dimethicone gums, dimethiconol gums, polydimethyl siloxane/diphenyl/methylvinylsiloxane copolymers, polydimethylsiloxane/methylvinylsiloxane copolymers and mixtures thereof. Examples include those materials described in US Pat. No. 4,152,416 (Spitzer) , and on General Electric Silicone Rubber product Data Sheet SE 30, SE 33, SE 54 and SE 76.

Also suitable for use in the present invention are silicone gums having a slight degree of cross-linking, as are described for example in WO 96/31188. These materials can impart body, volume and stylability to hair, as well as good wet and dry conditioning.

Preferred emulsified silicones for use in compositions of the invention have an average silicone particle size in the composition of less than 100, preferably less than 30, more preferably less than 20 microns, most preferably less than 10 microns.

Particle size may be measured by means of a laser light scattering technique, using a 2600D Particle Sizer from Malvern Instruments.

Suitable silicone emulsions for use in the invention are commercially available in a pre-emulsified form. This is particularly preferred since the pre-formed emulsion can be incorporated into the washing composition by simple mixing. Examples of suitable pre-formed emulsions include emulsions DC2-1766 and DC2-1784, available from Dow Corning. These are emulsions of dimethiconol. Crosslinked silicone gums are also available in a pre-emulsified form, which is advantageous for ease of formulation. A preferred example is the material available from Dow Corning as DC X2-1787, which is an emulsion of cross-linked dimethiconol gum.

The amount of silicone incorporated into the compositions of the invention depends on the level of conditioning desired and the material used. A preferred amount is from 0.01 to about 10% by weight of the total composition although these limits are not absolute. The lower limit is determined by the minimum level to achieve conditioning and the upper limit by the maximum level to avoid making the hair and/or skin unacceptably greasy. We have found that an amount of silicone of from 0.5 to 1.5% by weight of the total composition, is a particularly suitable level.

A further preferred class of conditioning agents are per- alk(en)yl hydrocarbon materials, used to enhance the body, volume and stylability of hair.

EP 567 326 and EP 498 119 describe suitable peralk(en)yl hydrocarbon materials for imparting stylability and enhanced body to hair. Preferred materials are polyisobutylene materials available from Presperse, Inc. under the PERMETHYL trade name.

The amount of per-alk(en) yl hydrocarbon material incorporated into the compositions of the invention depends on the level of body and volume enhancement desired and the specific material used. A preferred amount is from 0.01 to about 10% by weight of the total composition although these limits are not absolute. The lower limit is determined by the minimum level to achieve the body and volume enhancing effect and the upper limit by the maximum level to avoid making the hair unacceptably stiff. We have found that an amount of per-alk(en) yl hydrocarbon material of from 0.5 to 2% by weight of the total composition is a particularly suitable level.

Optional Ingredients

Compositions of this invention may contain any other ingredients normally used in hair treatment formulations. These other ingredients may include viscosity modifiers, preservatives, colouring agents, polyols such as glycerine and polypropylene glycol, chelating agents such as EDTA, antioxidants, fragrances, and sunscreens. Each of these ingredients will be present in an amount effective to accomplish its purpose. Generally these optional ingredients are included individually at a level of up to about 5% by weight of the total composition.

Preferably, compositions of this invention also contain adjuvants suitable for hair care. Generally such ingredients are included individually at a level of up to 2%, preferably up to 1%, by weight of the total composition.

Among suitable hair care adjuvants, are: (i) natural hair root nutrients, such as amino acids and sugars. Examples of suitable amino acids include arginine, cysteine, glutamine, glutamic acid, isoleucine, leucine, methionine, serine and valine, and/or precursors and derivatives thereof. The amino acids may be added singly, in mixtures, or in the form of peptides, e.g. di- and tripeptides. The amino acids may also be added in the form of a protein hydrolysate, such as a keratin or collagen hydrolysate. Suitable sugars are glucose, dextrose and fructose. These may be added singly or in the form of, e.g. fruit extracts. A particularly preferred combination of natural hair root nutrients for inclusion in compositions of the invention is isoleucine and glucose. A particularly preferred amino acid nutrient is arginine.

[ii) hair fibre benefit agents. Examples are:

- ceramides, for moisturising the fibre and maintaining cuticle integrity. Ceramides are available by extraction from natural sources, or as synthetic ceramides and pseudoceramides. A preferred ceramide is Ceramide II, ex Quest. Mixtures of ceramides may also be suitable, such as Ceramides LS, ex Laboratoires Serobiologiques.

The invention will now be further illustrated by the following, non-limiting Examples:

EXAMPLES

In the examples and throughout this specification all percentages are by weight unless indicated otherwise.

Raw Materials

The raw materials used in the examples are listed below.

Zinc pyrithione (ZPT) Needles ex Arch 25% aqueous solution

Batch NR-25-9805 Sodium polynaphthalene sulphonate (SPNS) Darvan 1™ ex RT

Vanderbilt Co Inc.

Polyvinylpyrrolidine/vinyl acetate 60:40 (PVP/VA) ex

BASF

Cocoamidopropylbetaine (CAPB) ex Goldschmidt Sodium Lauryl Ether Sulphate (SLES2EO) ex A&W

Ammonium Alkyl Sulphate (ALS) ex A&W

Ammonium Lauryl ether Sulphate (ALES) ex A&W

Silicone DC 1391™ ex Dow Corning

Silicone DC 1784™ ex Dow Corning Jaguar C13S™ ex Rhodia

Euperlan PK 3000™ ex Henkel

(A&W = Albright & Wilson Limited) Preparation and analysis of solutions under test

For each of Examples 1 and 2, a series of aqueous solutions was prepared according to a standard protocol given below: -

0.25% by weight ZPT was weighed into a 30 ml glass jar and the appropriate level of each raw material and distilled water added. Where appropriate, the pH of each solution was adjusted using 0.1M sodium hydroxide or citric acid. Resulting solutions were placed in an oven at 37 °C. After 4 days, the ZPT needle stability was assessed via optical microscopy. Where applicable, the aqueous zinc solubility as a function of pH was also determined. For measurement of aqueous zinc, each solution was centrifuged at 4,300 rpm for 20 minutes and 10 ml of the supernatant analysed for total water-soluble zinc by means of atomic adsorption spectroscopy.

EXAMPLE 1

Investigation into the effect of Sodium polynaphthalene sulphonate (SPNS) on stability of ZPT needles.

Preliminary investigations showed that 10% SPNS was effective at stabilising solutions of ZPT (0.25%) containing 10% CAPB. The needles were stable after two months at 37°C. The next stage of the investigation was to determine the level of SPNS required to stabilise solutions containing 0.5% ZPT needles, the level typically found in antidandruff shampoos. Aqueous solutions containing 14:2 (respective percentages by weight) SLES 2EO: CAPB, 0.5% ZPT needles and concentrations of 0, 0.5, 1, 2, 4, 6, and 10% SPNS were prepared adopting the following order of addition throughout :-

1. SLES 2EO

2. CAPB

3. SNPS

4. ZPT

Solutions were prepared at their natural pH (5.3 - 5.8) and stored at 37 °C. Stability of needles was monitored via optical microscopy.

After 3 months storage, the solutions containing 0.5% ZPT needles were found to be stable at all concentrations of SPNS.

EXAMPLE 2

Investigation into the effect of PVP/VA 60/40 on stability of ZPT needles.

Aqueous solutions containing 14:2 (respective percentages by weight) SLES 2EO: CAPB, 0.5% ZPT needles and concentrations of 0, 0.5, 0.1 and 0.3% PVP/VA 60/40 were prepared adopting the following order of addition throughout :-

1. SLES 2EO 2. CAPB 3 . PVP/VA

4 . Z PT

Solutions were prepared at their natural pH (5.5 - 5.6) and stored at 37°C.

After 3 months storage at 37 °C, ZPT needles were stable at all concentrations of PVP/VA 60/40 tested, as determined by optical microscopy.

COMPARATIVE EXAMPLE

Investigation into the effect of polyvinylsulfonic acid, sodium salt

Solutions containing concentrations of poly (vinylsulfonic acid, sodium salt) equivalent to the molar concentrations 2% SNPS and 0.2% PVP/VA (0.073 molar and 0.0106 respectively) were prepared adopting the same order of addition as for PVP/VA solutions. The natural pH was 6.96 and 6.65 respectively. The resulting solutions where stored at 37 °C and the stability of the ZPT needles was monitored via optical microscopy over a period of time.

At both concentrations of poly (vinylsulfonic acid, sodium salt) , ZPT needles had degraded to platelet-like particles after 2 months storage. This example shows that the two polymers SPNS and PVP/VA are more effective than poly (vinyl sulfonic acid, sodium salt) at stabilising ZPT needles in the surfactant base. EXAMPLES 3 TO 8

Stability testing of antidandruff shampoo containing ZPT needles

SPNS and polyvinylpyrrolidine/vinyl acetate 60/40 were formulated into a standard antidandruff shampoo formulation at the following concentrations: -

0% Polymer (control)

0.5%, 1%, 25 and 5% SNPS (Examples 3, 4, 5 and 6) 0.1% and 0.3% PVP/VA 60/40 (Examples 7 and 8)

Full formulation details are set out below:

Ingredient

SLES 2E0 (100%) 14.00

CAPB (30%) 6.67 Carbopol 980 0.50

Jaguar C-13S 0.10

Silicone X2-1766 (60%) 1.67

DL-Panthenol 0.10

Anstead Blue 0.0004 Formalin 0.10

Vit.E-acetate 0.05

Perfume 0.90

Euperlan PK 3000 8.00

ZnPTO-Needles (25%) 2.0 SPNS 0.5 or 1 or 2 or 5 (for Examples 3,

4, 5 and 6, respectively) PVP/VA 0.1 or 0.3 (for Examples 7 and 8, respectively)

Water to 100%

Each shampoo was stored for 6 months at room temperature, 37 °C and 45°C. Stability of the ZPT needles was checked after 1 week, 1, 2, 3, 5 and 6 months by means of an optical microscope. The appearance, viscosity and pH were also measured at the same time intervals.

In terms of ZPT needle stability, shampoos containing SPNS and PVP/VA were stable at all temperatures after 5 months with the exception of the shampoos containing 0.1% and 0.3% PVP/VA 60/40 where the ZPT showed some signs of degradation at 45°C. For the control shampoo containing no polymer, ZPT needles were stable after 5 months at room temperature, whereas at 37°C and 45°C, ZPT needles had degraded to platelet like particles. Furthermore at 45°C, ZPT needles had degraded to platelet like particles after 1 week.

Product appearance was assessed in terms of degree of separation as measured in mm. Results after 5 months stability are summarised below where it can be seen that the degree of separation of shampoos containing 0.5% SPNS and 0.1% PVP/VA 60/40 was no worse than the control at RT, 37 °C and 45°C. For higher concentration of these materials, the degree of separation increased with increasing temperature. Product Appearance

In-vitro sensory evaluation of ease of combing, smooth feel and lack of fly away on dry hair

An in-vitro sensory evaluation of ease of dry combing, smooth feel and lack of flyaway of hair switches was conducted on formulations containing 0.5, 2% SPNS and 0.1% and 0.3% PVP/VA to determine whether these stabilising ingredients adversely affect the dry properties of the hair fibre. Two separate tests were conducted comparing each polymer at the two different active levels to a control shampoo without polymer. It was found that there was no significant difference (95% confidence level) in terms of smooth feel or lack of flyaway between any of the products. For ease of dry combing however, the control was found to be significantly better than either of the two formulations containing SPNS. Comparing 0.1% PVP/VA, 0.3% PVP/VA and the control it was found that there were no significant differences between any of the formulations containing PVP/VA and the control for smooth feel, ease of dry combing or lack of flyaway.

Claims

CLAIMS :

1. Composition comprising an insoluble metal pyrithione in an unstable crystalline form, from 5 to 30% by weight of the composition of one or more surfactants and at least 0.001% by weight of the composition of a nonionic or anionic polymer which comprises a plurality of optionally substituted rings selected from phenyl, naphthyl, nitrogen- containing unsaturated heterocycles and mixtures thereof.

2. Composition as claimed in Claim 1, wherein the metal pyrithione is zinc pyrithione.

3. Composition as claimed in any one of the preceding claims, wherein the metal pyrithione is in the form of needles .

4. Composition as claimed in any one of the preceding claims, wherein the metal pyrithione is present in the composition in an amount of from 0.001% to 5% by weight.

5. Composition as claimed in any one of the preceding claims, wherein the polymer is a copolymer of an aldehyde and a compound comprising an optionally substituted naphthyl group.

6. Composition as claimed in any one of the preceding claims, wherein the polymer is a polysodium salt of polynaphthalene sulphonic acid.

7. Composition as claimed in any one of the preceding claims which is a hair treatment composition.

8. Composition as claimed in Claim 7 which is a shampoo.

9. A method of treating hair which comprises applying to the hair a composition as claimed in any one of Claims 1 to

10. A method as claimed in Claim 9 for the treatment of dandruff.

11. Use of a composition of any one of Claims 1 to 8 in the manufacture of a medicament for the treatment of dandruff.

12. Use of a polymer which is nonionic, anionic, cationic or zwitterionic and which comprises a plurality of carbocyclic or heterocyclic, aromatic or non-aromatic rings as a stabilising agent for zinc pyrithione in a composition comprising zinc pyrithione in an unstable crystalline form and a surfactant.

13. Use of, a polymer as claimed in Claim 12 wherein the polymer is a polymer or copolymer of vinylpyrrolidine.

14. Use of a polymer as claimed in Claim 13 wherein the polymer is a copolymer of vinylpyrrolidine and vinyl acetate.

15. Use of a polymer as claimed in Claim 12 wherein the polymer is a polysodium salt of polynapthalene sulphonic acid.