Field of the Invention

This invention relates to a method of treating hair. More particularly this invention relates to a method of treating oxidatively damaged hair.

Background of the Invention

The purpose of bleaching is to eliminate or lighten the natural hair colour by the reaction of an oxidizing agent with the melanin pigment. Examples of oxidizing agents that can be used are hydrogen peroxide, potassium, sodium or ammonium salts of perborate, percarbonate, persulfate and percarbamide, and mixtures thereof.

Bleaches are also used during oxidative dyeing treatments. Oxidative (or "permanent") dye compositions comprise "precursor dyes" which are small molecules capable of diffusing into the hair. These molecules mainly belong to three classes of aromatic compounds: diamines, aminophenols and phenols. They are sufficiently small to diffuse in the hair shaft where, once activated by an oxidizing agent such as hydrogen peroxide, they further react with other precursors to form larger coloured complexes.

Oxidative treatments of hair are very popular with consumers since they provide good results which are relatively unaffected by light, shampooing and perspiration. However the process is not without drawbacks. Repeated oxidative treatments over prolonged periods may damage or weaken hair, making it prone to breakage and reduced lustre.

Since the hair fibre is a multilayer structure, once hair is damaged, treatments must intervene on several levels to treat it - from the middle of the core to the surface of the cuticle.

Film-forming polymers are often used in treatments for damaged hair because they alter hair surface properties, imparting smoothing and gliding effects and shine, and have a significant impact on the macroscopic behavior of the hair array. However, film- forming polymers are by nature designed to provide hair fibres with a hydrophobic coating that may slow or prevent the penetration of actives. Therefore such treatments may not provide multilayer benefits to the fibre such as fibre strengthening, damage repair, hair shape smoothing and frizz control.

The present invention addresses this problem. Summary of the Invention

The present invention provides a method of treating oxidatively damaged hair by sequential topical application of:

(i) an aqueous composition comprising one or more silk sericins dissolved or dispersed in an aqueous continuous phase; and

(ii) a hair oil composition comprising one or more oily liquid hair conditioning

agents selected from oily liquid hydrocarbons, oily liquid glycerides and mixtures thereof. Detailed Description and Preferred Embodiments

All molecular weights as used herein are weight average molecular weights, unless otherwise specified.

The composition (i) for use in the invention comprises one or more silk sericins dissolved or dispersed in an aqueous continuous phase.

By "aqueous continuous phase" is meant a continuous phase which has water as its basis. A composition (i) for use in the invention will generally comprise from about 50 to about 98% water, preferably from about 60 to about 90% water (by weight based on the total weight of the composition).

Other organic solvents may also be present, such as lower alkyl alcohols and polyhydric alcohols. Examples of lower alkyl alcohols include C1 to C6 monohydric alcohols such as ethanol and isopropanol. Examples of polyhydric alcohols include propylene glycol, hexylene glycol, glycerol and propanediol. Mixtures of any of the above-described organic solvents may also be used.

The composition (i) for use in the invention comprises one or more silk sericins. Silks can be broadly defined as externally spun fibrous protein secretions, made by arthropods for a variety of task-specific applications. Silk fibres are typically composite materials formed of silk protein and other associated molecules such as glycoproteins and lipids. Silkworms produce silk cocoons to protect themselves during their metamorphosis into moths, and humans have harvested silk fibres from these cocoons for centuries to produce textiles. Of all natural silk-producing animals, mulberry silkworms (Bombyx mori) are of the most economic importance, because it is possible to rear them in captivity. Other than the domesticated B.mori, silk fibre production is reported from the wild non-mulberry saturniid variety of silkworms, such as tasar (Antheraea mylitta), muga (Antheraea assamensis) and eri (Philosamia ricini).

Silkworm (e.g. B.mori) silks are composed of two groups of proteins. The fibroins, which constitute the silk thread, are synthesized in the posterior part of the silk gland (PSG). The sericins are produced by the middle silk gland (MSG), and are a family of globular, water-soluble proteins which ensure the cohesion of the cocoon by sticking the fibroin fibres together. The sericins are characterized by their high serine content, where serine represents at least about 20 mol% of the total amino acid residues. Typically serine represents from about 20 to about 40 mol%, preferably from about 30 to about 40 mol% of the total amino acid residues.

A peptide consisting of 38 amino acids has been identified as a highly conserved and internally repetitive sequence of B.mori silk sericins. The consensus sequence of this peptide (Ser-Ser-Thr-Gly-Ser-Ser-Ser-Asn-Thr-Asp-Ser-Asn-Ser-Asn-Ser -Ala-Gly-Ser- Ser-Thr-Ser-Gly-Gly-Ser-Ser-Thr-Tyr-Gly-Tyr-Ser-Ser-Asn-Ser- Arg-Asp-Gly-Ser-Val) is characterized by its similarity to the average amino acid composition of silk sericin and its high hydrophilic amino acid content. Native B.mori silk sericins range in molecular weight from about 10 to about 400 kDa, depending on gene coding and post-translational modifications. Three major fractions of silk sericin have been isolated from the B.mori cocoon, with molecular weights of about 150, 250, and 400 kDa respectively. Silk sericins for use in the invention may be naturally derived, typically by extraction from silkworm (e.g. B.mori) cocoons or by extraction from raw silk. During the extraction process, the silk sericin may be hydrolysed to a certain extent, depending on the extraction method, temperature, pH and processing time. Accordingly, the molecular weight which is quoted for such materials will represent the average molecular weight of the various protein, polypeptide, oligopeptide and amino acid constituents present. The average molecular weight of silk sericins derived by boiling water extraction of cocoons generally ranges from about 65 kDa to about 400 kDa. If an alkaline solution is used, such as one containing sodium hydroxide, the average molecular weight of the derived silk sericin generally ranges from about 1 kDa to about 50 kDa.

Silk sericins for use in the invention may also be artificially synthesized using conventionally known biological methods, for example, by inserting the silk sericin gene sequence into E. coli, in which the E. coli produces recombinant silk sericin, or by conventionally known chemical methods such as Fmoc/tBu solid-phase peptide synthesis.

Artificially synthesized silk sericins will generally contain several repeats of the 38 amino acid consensus sequence described above (Ser-Ser-Thr-Gly-Ser-Ser-Ser-Asn- Thr-Asp-Ser-Asn-Ser-Asn-Ser-Ala-Gly-Ser-Ser-Thr-Ser-Gly-Gly- Ser-Ser-Thr-Tyr-Gly- Tyr-Ser-Ser-Asn-Ser-Arg-Asp-Gly-Ser-Val), for example 2 to 8 repeats, more preferably 2 to 6 repeats.

Mixtures of any of the above described types of silk sericins may also be used in the invention. Preferred silk sericins for use in the invention are naturally derived, and have an average molecular weight ranging from about 1 kDa to about 50 kDa, more preferably from about 5 to about 30 kDa and most preferably from about 10 kDa to about 30 kDa,

An example of a preferred silk sericin for use in the invention is silk sericin extracted from silkworm (e.g. B.mori) cocoons or raw silk, and containing serine at a level of from about 30 to about 40 mol% of the total amino acid residues, and having an average molecular weight ranging from about 1 kDa to about 50 kDa, more preferably from about 5 to about 30 kDa and most preferably from about 10 kDa to about 30 kDa. In a typical composition (i) for use in the invention, the level of silk sericin(s) generally ranges from about 0.5 to about 6% and preferably ranges from 1 to 3%, more preferably from 1.5 to 2.5% (by weight based on the total weight of the composition).

The composition (i) for use in the invention is intended for topical application to the hair and may be formulated as a rinse-off product or a leave-on product.

Rinse-off products are intended to be substantially rinsed off the hair of the user with water after use, such as shampoos. Rinse-off products also include conditioners which are intended for application to the hair post-wash and which may be rinsed immediately after application or (for more intensive conditioning), left on the hair for up to 2 hours, e.g. 5 minutes to 2 hours.

Leave-on products are intended not to be rinsed off the hair of the user immediately after use (i.e. within at least the first 2 hours, preferably at least four hours, after application of the product). Leave-on products include for example lotions, creams and serums for use in-between washes, and leave-on conditioners for application to the hair post-wash.

Examples of suitable product forms are shampoos and conditioners. A shampoo for use as composition (i) in the invention will typically include one or more anionic surfactants which are cosmetically acceptable and suitable for topical application to the hair.

Typical anionic surfactants for use in the invention include those surface active agents which contain an organic hydrophobic group with from 8 to 14 carbon atoms, preferably from 10 to 14 carbon atoms in their molecular structure; and at least one water- solubilising group which is preferably selected from sulphate, sulphonate, sarcosinate and isethionate. A preferred class of anionic surfactants for use in the invention are alkyl ether sulphates of general formula:

R-0-(CH ₂ CH2-0)n-S0 ₃ -M ⁺ in which R is a straight or branched chain alkyl group having 10 to 14 carbon atoms, n is a number that represents the average degree of ethoxylation and ranges from 1 to 5, preferably from 1 to 3.5, and M is an alkali metal, ammonium or alkanolammonium cation, preferably sodium, potassium, monoethanolammonium or triethanolammonium, or a mixture thereof.

Specific examples of such preferred anionic surfactants include the sodium, potassium, ammonium or ethanolamine salts of Cio to C12 alkyl sulphates and Cio to C12 alkyl ether sulphates (for example sodium lauryl ether sulphate (nEO) in which n ranges from 1 to 3.5).

The level of anionic surfactant will generally range from about 5 to 26%, and preferably ranges from 10 to 16% (by weight based on the total weight of the composition (i)).

A shampoo for use as composition (i) in the invention can optionally include co- surfactants, to help impart aesthetic, physical or cleansing properties to the

composition. A preferred type of co-surfactant is an amphoteric surfactant. Suitable amphoteric surfactants are betaines, such as those having the general formula

(CH3)2N ⁺ CH2COO ^" , where R is an alkyl or alkylamidoalkyl group, the alkyl group preferably having 10 to 16 carbon atoms. Particularly suitable betaines are oleyl betaine, caprylamidopropyl betaine, lauramidopropyl betaine, isostearylamidopropyl betaine, and cocoamidopropyl betaine.

Mixtures of any of the above described materials may also be used.

When included, the total level of amphoteric surfactant is generally from 0.1 % to 20%, preferably from 1 % to 10%, more preferably from 1 % to 5% (by weight based on the total weight of the composition (i)).

A shampoo for use as composition (i) in the invention may include one or more cationic deposition polymers which are selected from cationic polygalactomannans having a mean charge density at pH7 from 0.2 to 2 meq/g, preferably from 0.5 to 1.8 meq/g. Such polymers may serve to enhance the delivery of conditioning agents from the composition to the skin and/or hair surface during consumer use, thereby improving the conditioning benefits obtained. The term "charge density" in the context of this invention refers to the ratio of the number of positive charges on a monomeric unit of which a polymer is comprised to the molecular weight of the monomeric unit. The charge density multiplied by the polymer molecular weight determines the number of positively charged sites on a given polymer chain. The charge density is suitably determined via the Kjeldahl method as described in the US Pharmacopoeia under chemical tests for nitrogen determination.

Preferred cationic polygalactomannans for use in the invention include guar

hydroxypropyltrimethylammonium chlorides.

Guar hydroxypropyltrimethylammonium chlorides for use in the invention are generally comprised of a nonionic guar gum backbone that is functionalized with ether-linked 2- hydroxypropyltrimethylammonium chloride groups, and are typically prepared by the reaction of guar gum with N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride.

Cationic polygalactomannans for use in the invention (preferably guar

hydroxypropyltrimethylammonium chlorides) generally have an average molecular weight (weight average molecular mass (Mw) determined by size exclusion chromatography) in the range 500,000 to 3 million g/mol, more preferably 800,000 to 2.5 million g/mol.

Cationic polygalactomannans for use in the invention are commercially available from Rhodia as JAGUAR ® C13S, JAGUAR ® C14 and JAGUAR ® C17.

Mixtures of any of the above described materials may also be used.

When included, the total level of cationic polygalactomannan will generally range from 0.05 to 0.25%, and preferably ranges from 0.15 to 0.2% (by weight based on the total weight of the composition (i)).

A shampoo for use as composition (i) in the invention may include one or more suspending agents. Suitable suspending agents include 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.

Mixtures of any of the above suspending agents may be used. Preferred is a mixture of cross-linked polymer of acrylic acid and crystalline long chain acyl derivative.

When included, the total level of suspending agent is generally 0.1 to 10%, preferably from 0.5 to 6%, more preferably from 0.9 to 4% (by weight based on the total weight of the composition (i)). A conditioner for use as composition (i) in the invention may suitably include a structured liquid phase, which may be characterized as a lamellar gel network formed from cationic surfactant and fatty alcohol bilayers. The bilayers may grow, swell or fold to form extended sheets or spherical vesicles in the aqueous continuous phase of the composition (i).

Examples of suitable cationic surfactants include cetyltrimethylammonium chloride (CTAC), behenyltrimethylammonium chloride (BTAC) and mixtures thereof.

The level of cationic surfactant suitably ranges from 0.1 to 10%, preferably from 0.2 to 5% and more preferably from 0.25 to 4% (by total weight of cationic surfactant based on the total weight of the composition (i)). Examples of suitable fatty alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, and mixtures thereof.

The level of fatty alcohol suitably ranges from 0.01 to 10%, preferably from 0.1 to 8%, more preferably from 0.2 to 7% and most preferably from 0.3 to 6% (by weight based on the total weight of the composition (i)).

The weight ratio of cationic surfactant to fatty alcohol is suitably from 1 :1 to 1 :10, preferably from 1 :1.5 to 1 :8, optimally from 1 :2 to 1 :5. A composition (i) for use in the invention may also incorporate other optional ingredients to enhance performance and/or consumer acceptability. Suitable optional ingredients include: preservatives, colouring agents, chelating agents, antioxidants, fragrances, antimicrobials, antidandruff agents, cationic conditioning polymers, styling ingredients, sunscreens, proteins and hydrolysed proteins. Each of these optional i 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 (i).

The hair oil composition (ii) for use in the invention comprises one or more oily liquid hair conditioning agents selected from oily liquid hydrocarbons, oily liquid glycerides and mixtures thereof. For the purposes of the present invention, the term "oil" means a non-aqueous compound which is immiscible with water (distilled or equivalent) at a concentration of 0.1wt%, at 25°C. The term "oily liquid" means an oil that is capable of flowing under its own weight under ambient conditions (1 atmosphere, 25°C). Oily liquid hydrocarbons suitable for use in the invention will generally have a kinematic viscosity at 40°C of 1000 cS (mm ² .s ^"1 ) or less, preferably 500 cS (mm ² .s ^"1 ) or less, more preferably 50 cS (mm ² .s ^"1 ) or less, and most preferably 10 cS (mm ² .s ^"1 ) or less, such as from 0.5 to 10 cS (mm ² .s ^"1 ). Examples of such materials include C4-C50 straight or branched chain, saturated or unsaturated aliphatic or cycloaliphatic hydrocarbons and mixtures thereof. Straight chain hydrocarbons will preferably contain from about 12 to about 30 carbon atoms. Branched chain hydrocarbons can and typically may contain higher numbers of carbon atoms. Also suitable are polymeric hydrocarbons, such as polymers of C2-6 alkenyl monomers (e.g. polyisobutene, polybutene) and poly a-olefin oils derived from 1 -alkene monomers having from about 6 to about 16 carbons, preferably from about 6 to about 12 carbon atoms (e.g. polymers derived from 1 -octene, 1 -decene, 1-dodecene, 1- tetradecene, 1-hexadecene, and mixtures thereof). Polymeric hydrocarbons for use in the invention can be straight or branched chain polymers, and may be hydrogenated. The number average molecular weight of such polymeric materials can vary widely, but will typically range from about 200 up to about 3000.

Preferred oily liquid hydrocarbons for use in the invention include mineral oils. The term "mineral oil" in the context of this invention generally denotes an oily liquid mixture of saturated hydrocarbons with boiling points greater than 200°C, and which is obtained from petroleum (i.e. a mineral source). Mineral oil saturated hydrocarbons include straight chain (paraffinic), branched chain (isoparaffinic) and cyclic (naphthenic) structures, and molecules containing all three configurations, with the number of carbon atoms per hydrocarbon molecule generally ranging from about C15 to about C50. Mineral oils suitable for use in the invention are typically obtained from petroleum through various refining steps (e.g. distillation, extraction and/or crystallisation) and subsequent purification (e.g. acid treatment and/or catalytic hydrotreatment). Mineral oils may also be characterised in terms of their viscosity. "Light" mineral oils will generally have a kinematic viscosity of about 34 cS (mm ² .s ^"1 ) or less at 40°C and "heavy" mineral oils will generally have a kinematic viscosity ranging from about 35 cS (mm ² .s ^"1 ) up to about 240 cS (mm ² .s ^"1 ) at 40°C. Light mineral oils (as defined above) are preferred for use in the invention. More preferably such light mineral oils have a kinematic viscosity of about 10 cS (mm ² .s ^"1 ) or less at 40°C. Most preferably the kinematic viscosity ranges from about 3 to about 5 cS (mm ² .s ^"1 ) at 40°C. Materials of this type are commercially available from Sonneborn Inc. under the brand name Lytol®.

Mixtures of any of the above-described materials may also be used.

Oily liquid glycerides suitable for use in the invention will generally have a viscosity at ambient temperature (25 to 30°C) of from 0.01 to 0.8 Pa.s, preferably from 0.015 to 0.6 Pa.s, more preferably from 0.02 to 0.065 Pa.s, as measured by a Carri-Med CSL2 100 controlled stress rheometer, from TA Instruments Inc., New Castle, Del. (USA).

Examples of such materials include mono-, di- and triglycerides (and mixtures thereof) formed between glycerol and long chain carboxylic acids having at least 8 carbon atoms, preferably from 8 to 22 carbon atoms and more preferably from 8 to 18 carbon atoms. The carboxylic acids may be saturated or unsaturated, linear or branched chain, or contain hydrophilic groups such as hydroxyl.

Preferred oily liquid glycerides for use in the invention include triglycerides

corresponding to the following general formula (I):

in which R ¹ , R ² and R ³ are each independently selected from linear alkyl groups having from 7 to 17 carbon atoms and 0, 1 , 2 or 3 double bonds.

Oily liquid glycerides for use in the invention may be chemically synthesized by a condensation reaction, but are preferably derived from natural, particularly plant, sources.

Naturally-derived oily liquid glycerides suitable for use in the invention include almond oil, castor oil, coconut oil, sesame oil, sunflower oil and soybean oil. Coconut oil is particularly preferred. Coconut oil generally contains a mixture of triglycerides of general formula (I), with varying chain lengths of the R ¹ , R ² and R ³ groups. Typically at least about 85% of the R ¹ , R ² and R ³ groups have from 7 to 17 carbon atoms; and at least about 50% of the R ¹ , R ² and R ³ groups have from 7 to 1 1 carbon atoms (by weight based on total weight of the R ¹ , R ² and R ³ groups) A representative carbon chain length distribution for the R ¹ , R ² and R ³ groups in coconut oil triglycerides of general formula (I) is as follows:

C ₇ 5 to 10 wt%

C ₉ 5 to 10 wt%

Ci3 15 to 23 wt% The hair oil composition (ii) for use in the invention is intended for topical application to the hair.

Preferably, the level of oily liquid hair conditioning agents selected from oily liquid hydrocarbons, oily liquid glycerides and mixtures thereof is at least 95%, more preferably at least 98% (by weight based on the total weight of the hair oil composition (ii))-

A particularly preferred hair oil composition (ii) for use in the invention comprises at least 95%, more preferably at least 98% light mineral oil and/or coconut oil (by weight based on the total weight of the hair oil composition (ii)).

Alternatively, a hair oil composition (ii) for use in the invention may be formulated as a shampoo, or more preferably a conditioner, with additional ingredients as described above with respect to composition (i).

A hair oil composition (ii) for use in the invention may also incorporate other optional ingredients to enhance performance and/or consumer acceptability. Suitable optional ingredients include: preservatives, colouring agents, antioxidants, fragrances, sunscreens and antimicrobials. Each of these optional 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 hair oil composition (ii).

Advantageously, the method of the invention does not require the use of reducing agents, and compositions (i) and (ii) for use in the invention are generally substantially free of such materials. The term "substantially free" in the context of this invention means that reducing agents are absent or included in trace quantities only, such as no more than 0.1 %, preferably no more than 0.01 %, and more preferably from 0 to 0.001 % by weight based on the total weight of the respective composition. The term "reducing agent" in the context of this invention means an agent which is effective to break hair disulfide bonds when applied to hair for a period ranging from about 3 to 15 minutes and at a temperature ranging from about 20 to 30°C. Examples of such reducing agents are ammonium thioglycolate (in a solution having a pH of between about 7 and 10.5), glyceryl monothioglycolate (employed at a pH of less than 7), thioglycolic acid, dithioglycolic acid, mercaptoethyl amine, mercaptopropionic acid, dithioglycolate and alkali metal or ammonium sulfites or bisulfites.

A preferred method of treating hair according to the invention is a two-stage method in which aqueous composition (i) is topically applied to the hair and then hair oil composition (ii) is topically applied to the hair.

The aqueous composition (i) may suitably be topically applied to dry hair. The term "dry hair" in the context of this invention generally means hair from which free water (i.e. water disposed as a film or droplets on the cuticle surface) has been substantially removed. Hair may be dried by exposure to air, by use of a heated hair drying appliance, by rubbing with a water- absorbent article, or by a combination of any of these methods. Preferably, the dry hair will not have been washed or actively wetted, (such as by shampooing, conditioning, rinsing or otherwise treating with an aqueous composition) in the preceding 2 hours and more preferably in the preceding 3 hours prior to topical application of the aqueous composition (i), and will have been permitted to acclimatise to atmospheric conditions. In such circumstances there is substantially no free water present which interferes with the adsorption of the aqueous composition (i) on application. A suitable indicator of dry hair in the context of this invention would be a hair fibre whose calculated water content does not exceed 25% by weight based on the total weight of the hair fibre. Preferably, the aqueous composition (i) is topically applied to the hair at a temperature from 15 to 40°C, and more preferably at a temperature from 20 to 30°C.

Subsequent to its topical application, the aqueous composition (i) is suitably allowed to remain in contact with the hair without rinsing for a period ranging from 1 to 60 minutes, more preferably from 3 to 45 minutes. The hair oil composition (ii) is then topically applied to the hair.

Generally, the aqueous composition (i) is not rinsed off the hair prior to application of hair oil composition (ii). Suitably, the aqueous composition (i) is not rinsed off the hair and the hair so treated is dried or allowed to dry prior to application of hair oil composition(ii). The hair so treated may be dried naturally by exposure to air, by use of a heated hair drying appliance, by rubbing with a water-absorbent article, or by a combination of any of these methods. Preferably, the hair oil composition (ii) is topically applied to the hair at a temperature from 15 to 40°C, and more preferably at a temperature from 20 to 30°C.

Preferably the hair oil composition (ii) is massaged into the hair for a period which typically ranges from 30 seconds to 5 minutes and preferably ranges from 1 to 3 minutes. The hair oil composition (ii) may then be rinsed from the hair with water or cleansing shampoo if required, and the hair dried and styled.

The method of this invention is suitable for application to hair to improve properties such as smoothness, frizz control and volume-down. The term "volume-down" in the context of this invention generally means reduced visible bulkiness of the hair. For many consumers, improved hair volume-down provides a number of associated benefits, such as improved straightness, manageability and style retention.

The method of this invention is suitable for application to damaged hair, such as oxidatively-treated hair. The method is especially suitable for treating oxidatively damaged hair to provide benefits to the fibre such as fibre strengthening, damage repair, hair shape smoothing and frizz control. As used herein, the term "oxidatively-treated hair" means hair which has been subjected to any treatment comprising at least one step of contacting the hair with at least one oxidizing composition. Examples of oxidative treatments for human hair are bleaching, dyeing or perming. As used herein, the term "oxidizing composition" means a composition comprising at least one oxidizing agent suitable for use on hair, such as hydrogen peroxide, potassium, sodium or ammonium salts of perborate, percarbonate, persulfate and percarbamide, and mixtures thereof. Examples of such compositions are oxidative dye compositions and bleaching compositions.

The invention is further illustrated with reference to the following, non-limiting

Examples.

EXAMPLES

In the Examples, all ingredients are expressed by weight percent of the total formulation, and as level of active ingredient.

Comparative Examples (not according to the invention) are indicated by letter;

Examples according to the invention are indicated by number.

Experiment 1

Twice-bleached dark brown European wavy#6 switches of length 25 cm and weight 2gms, were treated as follows: Control: Soaked for 30 minutes in water

Example A: Soaked for 30 minutes in an aqueous solution of 2% silk sericin ^*

Example 1 : Soaked for 30 minutes in an aqueous solution of 2% silk sericin ^* then when dry treated with coconut oil at a level of 0.1 gm per gm of hair

Example B: Soaked for 30 minutes in water then when dry treated with coconut oil at a level of 0.1 gm per gm of hair ^* Sericin powder molecular weight 20 kDa, ex Huzhou Xintiansi Bio-tech Co., Ltd., China

A few fibres from all the switches were removed and prepared for wet DSC

measurements. The denaturation temperature Td was measured and the results are shown in Table 1.

Table 1

The last column shows that switches not connected by a letter are significantly different (>95%).

The Td increase from control for the combination of Example 1 (according to the invention) is seen to be synergistic. It is much greater in real and percent terms compared to the simple addition of the effects of silk sericin and coconut oil on their own (Examples A and B respectively).

Experiment 2

Switches were treated as in Experiment 1 and washed once in a stripping shampoo. It was found that the Example 1 switches showed excellent smoothing, volume down and frizz control compared to the other switches.

Experiment 3

Experiments 1 & 2 were repeated with the coconut oil substituted for an equivalent quantity of light mineral oil (Lytol, CAS No. : 8042-47-5, ex Sonneborn) . The mineral oil was observed to have an equivalent effect to the coconut oil in terms of smoothing, frizz control and damage repair, when combined with silk sericin in accordance with the invention.