WO1999066886A1

WO1999066886A1 - Antimicrobial hair treatment composition

Info

Publication number: WO1999066886A1
Application number: PCT/EP1999/004154
Authority: WO
Inventors: Peter Gallagher; Peter Christopher Konidaris; Tipawan Kreu-Nopakun; Edwin John Staples
Original assignee: Unilever Plc; Unilever N.V.; Hindustan Lever Limited
Priority date: 1998-06-24
Filing date: 1999-06-16
Publication date: 1999-12-29
Also published as: GB9813640D0; AR019705A1; AU4772699A

Abstract

An antimicrobial hair treatment composition comprising: (a) at least one surfactant, (b) particles of an insoluble particulate metal pyrithione in which at least about 50 % by number of the particles are needle shaped particles having a length of between 1 and 50 microns; and (c) a water soluble, cationic polymer wherein the cationic polymer is a deposition aid for the metal pyrithione particles. These hair treatment compositions combine the desirable properties of efficacy against dandruff, stability and aesthetic appeal.

Description

ANTIMICROBIAL HAIR TREATMENT COMPOSITION

Field of the Invention

This invention relates to antimicrobial hair treatment compositions for topical application to human hair and scalp for the treatment of, for example, dandruff. In particular, the invention relates to a hair treatment composition comprising a surfactant, water- insoluble antimicrobial particles and a cationic polymer which serves to enhance the deposition and retention of the particles on the hair and/or the scalp from the composition.

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 (hereinafter referred to as ZnPTO) is widely used in this context.

Generally, dispersed particles of the ZnPTO are suspended in the composition, which is then applied to the hair to deposit the ZnPTO on the hair and scalp.

A problem encountered with such compositions is that it is difficult to obtain a stable dispersion containing ZnPTO, since its specific gravity and insolubility leads to precipitation and separation during storage. Steps taken to prevent precipitation and separation of the ZnPTO particles have hitherto included restriction of the formulational base to highly viscous emulsions or gels, e.g., by incorporation of thickeners or bulking agents to give structural viscosity to the system and prevent ZnPTO settlement . Such an approach is frequently impractical for shampoo compositions and can give cloudy, aesthetically- inferior products.

Furthermore, the anti -dandruff benefits attainable from particles of ZNPTO incorporated in hair treatment compositions are frequently limited, owing to a poor level of deposition on the intended site; namely the hair and/or the scalp, but particularly the scalp.

A further problem encountered with such compositions is that acceptable aesthetic properties, such as pearlescence, of the compositions are often difficult to achieve. The general approach taken to improve the pearlescence is to incorporate pearlescent materials such as ethylene glycol distrearate in the compositions. However such an approach alone is frequently dissatisfactory owing to the presence of metal pyrithione particles interfering with the ability of the pearlescent materials to deliver acceptable pearlescence. To address this problem, the prior art teaches that ZnPTO crystals having a flat plate-like morphology interfere less with pearlescers in such compositions. For example EP 34385 describes an aesthetically improved anti-dandruff hair care composition comprising flat, platelet shaped ZnPTO crystals. JP 8283242A describes a "mica like" shaped l-hydroxy-2- pyridinethione heavy metal salt for use in hair care compositions. The mica shaped crystals are said not to impede pearlescence.

There continues to be a need, however, for alternative antimicrobial hair treatment compositions to effectively address the above-mentioned problems and particularly which combine the properties of efficacy, stability and aesthetic appeal .

It has now been found that antimicrobial hair treatment compositions which have good mechanical stability, good optical properties and excellent anti-dandruff ability can be obtained by utilising needle-shaped particles of insoluble particulate metal pyrithione in combination with a deposition aid.

Summary of the Invention

Accordingly, in one aspect the present invention provides an antimicrobial hair treatment composition comprising:

(a) at least one surfactant

(b) particles of an insoluble particulate metal pyrithione in which at least about 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns; and

(c) a water soluble, cationic polymer wherein the cationic polymer is a deposition aid for the metal pyrithione particles.

According to a second aspect the invention also provides a method of treating dandruff comprising applying to the hair a composition according to the first aspect of the present invention.

According to a further aspect of the present invention there is provided the use, in an antimicrobial hair treatment composition, of particles of an insoluble particulate metal pyrithione in which at least 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns.

According to a still further aspect of the present invention there is provided the use of particles of an insoluble particulate metal pyrithione in which at least 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns for improving pearlescence of an antimicrobial hair treatment composition.

Detailed Description and Preferred Embodiments

The insoluble particulate 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 term "needle-shaped" particle used herein is used to describe a generally elongate three dimensional particle of any transverse cross-sectional shape, the particle having one dimension, the 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 particularly critical it is typically polygonal .

The needle-shaped particles of metal pyrithione 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 microns. 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 microns; most preferably between 4 and 30 microns and even more preferably between 5 and 15 microns; the most preferred length being between 10 and 15 microns. 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 microns; most preferably between 4 and 30 microns and even more preferably between 5 and 15 microns; the most preferred length is between 10 and 15 microns. 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 microns; most preferably between 4 and 30 microns and even more preferably between 5 and 15 microns; the most preferred length being between 10 and 15 microns. 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 metal 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%.

Preparation Process

The needle-shaped particles of a metal pyrithione may be prepared by mixing a water-soluble salt of pyrithione (such as sodium pyrithione) and a dispersant (such as DARVAN 1, a dispersant which is the sodium salt of polymerized alkyl naphthalene sulphonic acid) while maintaining stirring of this mixture at a temperature of between 20 and 60 degrees Celsius. The stirring is suitably effected using a paddle mixer having a paddle speed of from 50 to 150 rpm. The amount of dispersant added should be sufficient to provide from about 0.05 to about 10% by weight of dispersant, based on the total weight of the final reaction mixture. An aqueous solution of a polyvalent metal salt (for example a zinc salt such as zinc sulphate monohydrate) is then gradually added to the reaction mixture while continuing mixing at the specified paddle speed. Preferably, the amount of polyvalent metal salt is used in a slight (such as 5%) stoichiometric excess, relative to the amount of water-soluble pyrithione salt employed. The temperature of the reaction mixture should be maintained at between 20 and 60 degree Celsius, and stirring of the reaction mixture continued until all of the polyvalent metal salt solution has been added and a precipitate forms. The resulting rods and needles of insoluble zinc pyrithione salt are collected by vacuum filtration and washed in cold water. The rods and needles of ZnPTO produced by this method are generally about 0.1 to 1.0 microns width and 1 to 50 microns in length. The composition according to the invention also comprises at least one surfactant, preferably chosen from anionic, cationic, nonionic, amphoteric and zwitterionic surfactants, and mixtures thereof .

A particularly preferred hair treatment composition in accordance with the invention is a shampoo composition in which at least one surfactant provides a deterging benefit. The deterging surfactant is preferably selected from anionic, nonionic, amphoteric and zwitterionic surfactants, and mixtures thereof .

Suitable anionic surfactants include the alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates, N- alkoyl 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 oneto 10 ethylene oxide or propylene oxide units per molecule, and preferably contain 2 to 3 ethylene oxide units per molecule.

Examples of suitable anionic surfactants include sodium oleyl succinate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, sodium dodecylbenzene sulphonate, triethanolamine dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauroyl isethionate and sodium N-lauryl sarcosinate. The most preferred anionic surfactants are sodium lauryl sulphate, triethanolamine lauryl sulphate, triethanolamine monolauryl phosphate, sodium lauryl ether sulphate 1E0, 2E0 and 3E0, ammonium lauryl sulphate and ammonium lauryl ether sulphate 1E0, 2E0 and 3E0.

Nonionic surfactants suitable for use in compositions of the invention may include condensation products of aliphatic

(Cg-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 suitable nonionics include mono- or di-alkyl alkanolamides . Example include coco mono- or di- ethanolamide and coco mono-isopropanolamide .

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

The surfactants are present in shampoo compositions of the invention in an amount of from 0.1 to 50% by weight of the composition, preferably from 0.5 to 30% by weight.

Hair treatment compositions in accordance with the invention may also take the form of hair conditioning compositions, which preferably comprise one or more cationic surfactants. The use of cationic surfactants is especially preferred, because these ingredients are capable of providing conditioning benefits to hair.

Examples of cationic surfactants include:

quaternary ammonium hydroxides, e.g., tetramethylammonium hydroxide, alkyltrimethylammonium hydroxides wherein the alkyl group has from about 8 to 22 carbon atoms, for example octyltrimethylammonium hydroxide, dodecyltrimethy- ammonium hydroxide, hexadecyltrimethylammonium hydroxide, cetyltrimethylammonium hydroxide , octyldimethylbenzylammonium hydroxide, decyldimethyl- benzylammonium hydroxide, stearyldi-methylbenzylammonium hydroxide, didodecyldimethylammonium hydroxide, dioctadecyldimethylammonium hydroxide, tallow trimethylammonium hydroxide, cocotrimethylammonium hydroxide, and the corresponding salts thereof, e.g., chlorides Cetylpyridinium hydroxide or salts thereof, e.g., chloride Quaternium -5 Quaternium -31 Quaternium -18 and mixtures thereof .

In hair conditioning compositions according to 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.

Hair treatment compositions of the invention may also contain one or more conditioning agents, preferably selected from silicones, protein hydrolyzates and quaternised protein hydrolysates and other materials which are known in the art as having desirable hair conditioning properties.

Silicones are the most preferred conditioning agents.

Suitable silicones include volatile and non-volatile silicones, such as for example polyalkylsiloxanes, polyalkylaryl siloxanes, siloxane gums and resins, cyclomethicones, aminofunctional silicones, quaternary silicones and mixtures thereof. Silicone oil is a particularly preferred conditioning agent for hair. The silicone may be in the form of a low viscosity oil which may contain a high viscosity oil or gum in solution. Alternatively, the high viscosity material may be in the form of an emulsion in water. The emulsion may be of high viscosity oil or of a solution of gum in a lower viscosity oil. The particle size of the oil phase may be anywhere in the range from 30 nanometres to up to 20 microns average size .

The silicone oil may suitably be a polydimethylsiloxane with an average particle size of less than 20 microns and preferably less than 2 microns. Small particle size enables a more uniform distribution of silicone conditioning agent for the same concentration of silicone in the composition. Advantageously, a silicone with a viscosity in the range 1- 20 million cst is used. The silicone can be cross-linked.

Suitable protein hydrolysates include lauryl dimonium hydroxy propylamino hydrolysed animal protein, available commercially under the trade name AMEQUAT L, and hydrolysed keratin containing sulphur-bearing amino acids, available commercially under the trade name CROQUAT WKP . In accordance with the invention, the hair treatment composition also comprises a polymeric water-soluble cationic polymer as a deposition aid for the needle-shaped particles. The term "deposition aid" is defined herein as an agent which enhances deposition of the needle-shaped particles of metal pyrithione on the intended site, i.e., the hair and/or the scalp.

The deposition aid will generally be present at levels of from 0.01 to 5%, preferably from about 0.05 to 1%, more preferably from about 0.08% to about 0.5% by weight.

Preferably the cationic charge density, which is defined as the reciprocal of the molecular weight of a monomeric unit of the polymer containing 1 charge is at least 0.1 meq/g, preferably above 0.8 or higher. The cationic charge density should not exceed 4 meq/g, it is preferably less than 3 and more preferably less than 2 meq/g. The charge density can be measured using conductimetric analysis and should be within the above limits at the desired pH of use, which will in general be from about 3 to 9 and preferably between 4 and

Preferred deposition aids are cationic derivatives of guar gum and cationic polyacrylamides .

Suitable cationic derivatives of guar gum 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 and JAGUAR 162 which is a high transparency, medium viscosity guar having a low degree of substitution. Particularly preferred deposition aids are Jaguar C13S with a cationic charge density of 0.8 meq/g.

Suitable cationic polyacrylamides are described in WO 95/22311 whose contents are incorporated herein by reference .

The composition may further comprise from 0.1 to 5 % of a suspending agent. Examples are polyacrylic acids, cross linked polymers of acrylic acid, copolymers of acrylic acid with a hydrophobic monomer, copolymers of carboxylic acid- containing monomers and acrylic esters, cross-linked copolymers of acrylic acid and acrylate esters, heteropolysaccharide gums and crystalline long chain acyl derivatives. The long chain acyl derivative is desirably selected from ethylene glycol stearates, alkanolamides of fatty acids having from 16 to 22 carbon atoms and mixtures thereof. Polyacrylic acid is available commercially as Carbopol 420, Carbopol 488 or Carbopol 493. Polymers of acrylic acid cross-linked with a polyfunctional agent may also be used, they are available commercially as Carbopol 910, Carbopol 934, Carbopol 940, Carbopol 941 and Carbopol 980. An example of a suitable copolymer of a carboxylic acid containing a monomer and acrylic acid esters is

Carbopol 1342. All Carbopol materials are available from Goodrich and Carbopol is a trade mark. A further suitable suspending agent is dihydrogenated tallow phthalic acid amide (available from Stepan under the trademark Stepan TAB- 2) .

Suitable cross linked polymers of acrylic acid and acrylate esters are Pemulen TR1 or Pemulen TR2. A suitable heteropolysaccharide gum is xanthan gum, for example that available as Kelzan mu.

Another ingredient that may advantageously be incorporated into hair treatment compositions of the invention is a fatty alcohol material. The use of these materials is especially preferred in conditioning compositions of the invention, in particular conditioning compositions which comprise one or more cationic surfactant materials. The combined use of fatty alcohol materials and cationic surfactants in conditioning compositions is believed to be especially advantageous, because this leads to the formation of a lamellar phase, wherein the cationic surfactant is dispersed.

Preferred fatty alcohols comprise from 8 to 22 carbon atoms, more preferably 16 to 20. Examples of preferred fatty alcohols are cetyl alcohol and stearyl alcohol. 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 materials 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 preferably from 10:1 to 1:10, more preferably from 4:1 to 1:8, most preferably from 1:1 to 1:4.

A further ingredient that may be desirably included in the hair treatment composition is a pearlescent material. Suitable pearlescent materials include ethylene glycol distearate, ethylene glycol monostearate, guanine and titanium dioxide coated micas, bismith oxychloride, and stearic monoethanol amide. The level of pearlescent material present in the composition is generally 0.1% to 5%, preferably from 0.3% to 3% by weight of the composition.

The hair treatment compositions of the invention are preferably aqueous based. The compositions suitably comprise water in amount of from about 20 to about 99% by weight of the total composition.

The compositions of the invention are preferably rinse-off compositions, i.e., suitable for applying to the hair and/or scalp, left thereon for an appropriate period of time and then rinsed off with water. Thus, shampoos and conditioners are a particularly preferred product form for compositions of the invention.

Depending on the type of composition employed, one or more additional ingredients conventionally incorporated into hair treatment formulations may be included in the compositions of the invention. Such additional ingredients additional antimicrobial agents, foam boosters, perfumes, colouring agents, preservatives, thickeners, viscosity modifiers, proteins, polymers, buffering or pH adjusting agents, moisturising agents, herb or other plant extracts and other natural ingredients.

The invention is further illustrated by way of the following non-limitative examples, in which all percentages are by weight based on total weight of the composition, unless otherwise specified. Example 1

The shape and size of the particles of ZnPTO prepared as described hereinbefore under the heading "Preparation Process" were determined using electron microscopy in the following manner.

A sample of ZnPTO particles prepared as described hereinbefore was shaken thoroughly and 10 microlitres was removed by pipette and diluted with 18 mililitres of water. A small amount of the diluted sample was placed onto an aluminium stub and left to air dry for two hours afterwhich the stub plus diluted sample was placed under vacuum for 48 hours. The samples were then coated with gold Ca 5nm to aid conductivity before imaging at lOkv. Ten photographic images of the sample were taken. Total number (T) of whole needles in each photograph were counted and measured. Those particles having a length of between 1 and 50 microns, which dimension was substantially greater than its other two, represented "needle-shaped particles" (N) as defined hereinbefore. The percentage by number of the particles in the sample that were needle-shaped particles having a length of between 1 and 50 microns was accordingly determined by the calculation (N/T)X 100.

Example 2

Comparative Assessment of Pearlescence of Shampoos

The pearlescence of shampoo formulations in accordance with the present invention were investigated in the following experiment . Protocol

All the test shampoos were made from a common base, namely 14 % sodium lauryl ether sulphate (2EO) , 2% cocamidopropylbetaine, 0.1 % JAGUAR C13S (guar hydroxypropyltrimonium chloride, ex Rhodia) , 6% pearlising agent Mirasheen CP 820, ex Rhodia and suspending, colouring and preserving agents. The following ZNPTO particles were additionally added to the test shampoos A to E.

Shampoo ZNPTO Particle Size and Shape %

A 0.5 micron diameter sphere 0.3

B 5 micron length needle 0.3 C 0.5 micron diameter sphere 0.5

D 5 micron diameter sphere 0.5

E 5 micron length needle 0.5

Shampoos B and E contain ZnPTO particles in which at least 50% by number thereof are ZnPTO needles according to the present invention. Shampoos A, C,and D contain standard size ZnPTO particles ex Olin and thus serve as comparative examples outside the present invention.

20g of each shampoo was poured into a separate Petri dish size 15 x 100 mm and placed on white paper. A spatula was used to make a line on the surface of the shampoo. The samples were left for 30 seconds prior to visual assessment. A number was assigned to each shampoo to represent the level of pearlescence depending on the effect observed according to the following scale: Effect Observed Scale of

Pearlescence

No line visible 0 (Poor) Line visible but unclear 1 (Fair)

Sharp Line Visible 2 ( Good)

Results

Shampoo Scale of Pearlescence

A 1

B 2

C 0

D 1 E 2

The results show that the pearlescence of shampoo composition B containing needle-shaped ZnPTO is better than composition A, identical to B except for containing prior art ZnPTO particles. The results also show that composition E containing needle-shaped ZnPTO particles is better than compositions C and D, identical to E except for containing prior art ZnPTO particles.

Examples 3

Hair shampoo compositions in accordance with the present invention, comprising needle-shaped particulate metal pyrithione and a deposition polymer were prepared using techniques well known in the art. The ZnPTO particles were prepared as described herein. The composition had the following formulation. INGREDIENT % BY WEIGHT

EXAMPLE 1

Sodium lauryl ether 20 sulphate 2EO (70% active)

Cocamidopropyl betaine 6.6 (30% active)

Jaguar C13S 0.1

ZnPTO, needle-shaped particle 2 (25% active) (5 micron length)

CARBOPOL 980 0.5

Ethylene glycol distearate 8.0

Dimethicone (60% aqueous 1.67 emulsion)

Vitamin E acetate 0.05

Preservative, colour, q.s, fragrance

Water - to 100^: This shampoo gave excellent anti-dandruff performance on the hair, had a good pearlescent quality and was stable without visible signs of separation after three months storage both at room temperature and at 45° C.

Claims

1. An antimicrobial hair treatment composition comprising:

(a) at least one surfactant

(b) particles of an insoluble particulate metal pyrithione m which at least about 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns; and

2. A composition according to claim 1 wherein metal pyrithione is zinc pyrithione.

3. A composition according to any preceding claim wherein the metal pyrithione is present m the composition in an amount of from 0.05 to 3% by weight of the composition.

4. A composition according to any preceding claim wherein at least about 50% by number of the particles have a length of between 2 and 40 microns, preferably between 4 and 30 microns, most preferably between 10 and 15 microns .

5. A composition according to any preceding claim wherein it comprises from 0.1% to 5% by weight of the composition of a pearlescent material.

6. A composition according to any preceding claim wherein the cationic polymer is a cationic derivative of guar gum or a cationic polyacrylamide .

7. A composition according to any preceding claim wherein the composition is a shampoo composition in which at least one surfactant is selected from anionic, nonionic, amphoteric and zwitterionic surfactants, and mixtures thereof, the total amount of surfactant being from about 0.1 to about 50% by weight of the composition.

8. A composition according to any preceding claim which further comprises a conditioning agent selected from volatile and nonvolatile silicones.

9. A method of treating dandruff comprising applying to the hair an antimicrobial composition comprising a composition as claimed in any of claims 1 to 8.

10. Use in an antimicrobial hair treatment composition of particles of an insoluble particulate metal pyrithione in which at least 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns.

11. Use of particles of an insoluble particulate metal pyrithione in which at least 50% by number of the particles are needle shaped particles having a length of between 1 and 50 microns for improving pearlescence of an antimicrobial hair treatment composition.