A personal cleansing composition

Abstract

The present invention relates to a personal cleansing composition for enhanced deposition of bioactives. It more particularly relates to a liquid cleansing composition which in addition to delivering enhanced deposition of actives ensures that there is no compromise on sensory benefits like acceptable viscosity. This is achieved by combining bioactives like hydroxy stearic acid and ketostearic acid in specific weight ratios.

Description

[0001] A PERSONAL CLEANSING COMPOSITION

[0002] Field of the Invention

[0003] The present invention relates to a personal cleansing composition for enhanced deposition of bioactives. It more particularly relates to a liquid cleansing composition which in addition to delivering enhanced deposition of actives ensures that there is no compromise on the sensory benefits like acceptable viscosity.

[0004] Background of the Invention

[0005] Personal cleansing compositions are used to primarily clean topical surfaces of the human and animal body thereby maintaining hygiene. Such compositions are delivered in many forms like bars, liquids, gels, and emulsions. Personal cleaning compositions, also known as wash-off compositions, are used to remove dirt and soil from the skin. It involves applying the composition generally diluted with water on to the skin to generate a foamy liquid. The foamy liquid along with dirt and oil are removed from the skin surface by rinsing with copious amount of water.

[0006] In addition to providing good cleansing of the skin, several other actives are included to deliver skin health benefits (also known as bioactives) like vitamins, skin glow agents, sunscreens, immunity benefit agents among others. The present applicant has filed patent applications on one such benefit agent viz. hydroxy stearic acid (HSA) which was found to have many skin benefits e.g. immunity, skin glow etc. While hydroxystearic acid e.g 12-hydroxystearic (12-HSA) is found to be highly efficacious for the above benefits when delivered in sufficient amounts on the skin, liquid cleansing compositions comprising them are found to have certain drawbacks. Like most other actives, it is difficult to ensure sufficient deposition of actives from a wash-off composition, as the primary aim of the product is removal (of dirt and oil from the surface). The competing mechanism of deposition of a desired active on the skin surface is therefore a challenge from wash-off compositions. The present applicants have also found it difficult to incorporate high amount of 12-HSA in an aqueous composition as it is found to thicken the composition undesirably so that it affects the pourability, e.g. it has been found that it is difficult to incorporate 12-HSA higher than about 0.5% in a liquid composition without affecting the pourability.

[0007] US2613182A relates to a lubricating grease composition containing soaps of keto-acids of the long chain monocarboxylic type.

[0008] US2283683A relates to a process of the isolation and purification of long-chain aliphatic aminoacyl compounds. US5464554 relates to s solid detergent composition.

[0009] DE10 2015 213478A1 relates to a stabilizing mixture, i.e. a finely divided dispersion of hydrogenated castor oil in water with anionic, amphoteric and non-ionic surfactants, which is suitable for stabilizing the pearl luster of surfactant agents, in particular cosmetic agents.

[0010] The present inventors found to their utter surprise that a compound chemically close to HSA viz ketostearic acid (KSA) which is usually present as an impurity (at about 2 wt% of HSA) during manufacture of HSA, when combined with HSA at various weight ratios, it was able to solve most of the above problems. When the bioactives are combined in the selective ratio range, the viscosity of the liquid composition was also stable i.e not thicken thereby ensuring pourability. The deposition of KSA was also seen to be considerably higher than that of HSA. Other sensorial property like foaming was observed to be acceptable.

[0011] WO2009 / 153169 discloses compositions comprising heterosubstituted saturated or unsaturated aliphatic acids albeit for skin lightening purposes particularly from a leave-on composition. The above specific range of weight ratios are not disclosed for enhanced deposition from a wash-off composition.

[0012] It is thus an object of the present invention to ensure high deposition of bioactives from a wash- off composition.

[0013] Summary of the Invention

[0014] The present invention relates to a personal cleansing composition comprising:

[0015] (i) a hydroxystearic acid

[0016] (ii) a ketostearic acid; and

[0017] (iii) 3.0 to 80 wt% synthetic anionic surfactant wherein the weight ratio of hydroxystearic acid to ketostearic acid is in the range of 15:1 to 1 :500.

[0018] Detailed Description of the Invention

[0019] Any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of’ or “composed of.” In other words, the listed steps or options need not be exhaustive. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and / or use are to be understood as modified by the word “about”. Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated. Unless specified otherwise, amounts as used herein are expressed in percentage by weight based on total weight of the composition and may be abbreviated as “wt%”. The use of any and all examples or exemplary language e.g. “such as” provided herein is intended merely to better illuminate the invention and does not in any way limit the scope of the invention otherwise claimed.

[0020] The composition of the present invention is suitable for the purpose of cleansing a surface e.g. skin. Preferably, the composition is in liquid form. By liquid form is meant a composition that is easily pourable form a bottle with sufficiently high viscosity that sufficient amount e.g. 5 to 10 mL can be poured into a cupped palm. The viscosity is therefore preferably in the range about 1000 to about 20,000 mPa.s. The liquid composition may then be applied on to the skin using suitable means, often using hands, and alternatively using a sponge, loofah or similar material along with copious amount of water to create lather; which is rinsed off with water to cleanse the surface, e.g. the skin. "Skin" as used herein is meant to include skin on the face and body e.g., neck, chest, back, arms, underarms, hands, legs and scalp.

[0021] The composition of the invention comprises hydroxystearic acid. It is preferred that the hydroxystearic acid is 8-hydroxystearic acid, 10-hydroxystearic acid, 12-hydroxystearic acid or trihydoxystearic acid (e.g. 9,10,13-trihydroxystearic acid) or trihydroxy stearin; also included are compounds that yield one or more molecules of hydroxystearic acid or hydroxystearate on their breakdown like mono, di or tri ester of glycerol with hydroxy stearic acid. Of these, 10- hydroxystearic acid, 12-hydroxystearic acid and 9,10,13-trihydroxystearic acid are more preferred, 12-hydroxystearic acid (12-HSA) being most preferred. 12-HSA has the structure as given below: Hydroxystearic acid is preferably included in 0.05 to 10 wt%, more preferably 0.1 to 5%, further more preferably 0.1 to 2%, even further more preferably 0.1 to 1 % by weight of the composition.

[0022] The composition of the invention also includes ketostearic acid. The preferred ketostearic acid for inclusion in the composition of the invention are 7-ketostearic acid, 9-ketostearic acid, 10- ketostearic acid, 12-ketostearic acid or mixtures thereof. The most preferred ketostearic acid is 12-ketostearic acid. Structure of 12-ketostearic acid is given below:

[0023] Ketostearic acid is preferably included in 0.05 to 10 wt%, more preferably 0.1 to 5%, further more preferably 0.1 to 2%, even further more preferably 0.1 to 1% by weight of the composition.

[0024] The weight ratio of hydroxystearic acid to ketostearic acid in the composition of the present invention is in the range of 15:1 to 1 :500. The weight ratio is preferably in the range of 15:1 to 1 :100 more preferably in the range of 10:1 to1 :20, further more preferably in the range of 5:1 to 1 :10, even further more preferably in the range of 3:1 to 1 :3. An especially preferred weight ratio range is from 2:1 to 1 :2 and most preferably in the range of 1.5:1 to 1 :1.5. It is preferred that the total amount of hydroxy stearic acid and ketostearic acid is in the range of 0.1 to 10 wt%. Throughout this specification, any reference to hydroxystearic acid and ketostearic acid, also includes salts or esters thereof. The acids may be partially neutralised and therefore the composition could include a mixture of the acid and its salt.

[0025] The composition of the invention also includes a synthetic anionic surfactant in 3.0 to 80 wt%, preferably 4.0 to 40 wt%, further more preferably 6 to 20 wt%. Preferred synthetic anionic surfactants for inclusion in the composition of the invention are one or more of isethionates, taurates, glycinates, alkyl sulfates, alkyl ether sulphates, succinates, sulphosuccinates, amphoacetates, sarconsinates, glutamates, a-olefin sulphonates, lactylates, methyl ester sulfonates and mixtures thereof.

[0026] Preferred synthetic anionic surfactants are selected from isethionates, taurates, glycinates, alkyl sulfates, alkyl ether sulfates (AES), alpha olefin sulfonates (AOS) and mixtures thereof. More preferably, the synthetic anionic surfactant is selected from soaps, alkyl sulfates, alkyl ether sulfates and mixtures thereof. Even more preferably, alkyl ether sulfates are used as the synthetic anionic surfactants in the composition. Synthetic anionic surfactants are known to provide foam and cleansing action.

[0027] Examples of alkyl sulfates that may be used as the synthetic anionic surfactant in the composition include sodium lauryl sulfate (SLS), sodium myristyl sulfate and mixtures thereof. Examples of AES that may be used as a synthetic anionic surfactant include anionic surfactants of the general formula:

[0028] Ri-(OR’)n-O-SO3' M+, wherein:

[0029] Ri is saturated or unsaturated Cs-Cis, preferably C12-C16 alkyl chain; preferably, R1 is a saturated Cs-Ci8, more preferably a saturated C12-C16 alkyl chain;

[0030] R’ is ethylene; n is from 1 to 18; preferably from 1 to 15, more preferably from 1 to 10 and even more preferably from 1 to 5,

[0031] M+is a suitable cation which provides charge neutrality, preferably ammonium, sodium, calcium, potassium, or magnesium, more preferably a sodium cation.

[0032] Examples of AES that may be used as the synthetic anionic surfactants in the composition include sodium lauryl ether sulfate (SLES), sodium myristyl ether sulfate and sodium palmityl ether sulfate and mixtures thereof. Preferred AES is SLES having 1 to 3 ethylene oxide units per molecule. SLES having 1 to 2 ethylene oxide units per molecule is more preferred.

[0033] Another class of synthetic anionic surfactants which is particularly desirable are alkyl isethionate (e.g., fatty acid esters of isethionate acid such as sodium lauroyl or sodium cocoyl isethionate) and alkyl taurate (e.g., alkyl taurate amides such as N-methyl taurate). Especially suitable is to include them as a surfactant mixture as they have the advantage that they are sulfate-free. Further, they offer the ability to formulate systems at neutral and slightly acidic pH.

[0034] An especially preferred aspect relates to compositions comprising 5 to 20%, preferably 6 to 15% by weight of a surfactant system which comprises (a) alkali metal acyl isethionate, (b) alkali metal alkyl taurate.

[0035] Acyl isethionate surfactant is commonly produced by the direct esterification of a fatty acid (e.g., C10 to C16 fatty acid such as lauric acid) and isethionate (e.g., HOCH2CH2SO3M+’ where M+may be, for example, a sodium or potassium counterion) in a process commonly known as the “DEFI” process, where DEFI refers to directly esterified fatty acid isethionate. Preferred isethionate sulfonates include methyl cocoyl isethionate and lauroyl isethionate. They preferably have sodium or potassium as counterions.

[0036] The other preferred synthetric anionic surfactant for inclusion in the composition of the invention are alkyl taurates, e.g., alkyl taurate amides. Such alkyl taurate amides may be made by reaction of a taurine; methyl taurine; or a corresponding taurate salt (e.g., NH2CH2CH2SO3 M+, where M+may be sodium or potassium counterion) with the appropriate fatty acid. Preferably alkyl taurate amides include sodium methyl cocoyl taurate and sodium methyl lauroyl taurate.

[0037] The composition may also be delivered with a combination of one or more of the above mentioned synthetic anionic surfactant together with a soap other than salt of HSA or KSA. The soap for preparing the cleansing composition of the invention is preferably a C8-C24 soap, more preferably C10-C20 soap and most preferably C12-C18 soap. The cation of the soap can be alkali metal, alkaline earth metal or ammonium. Preferably, the cation of the soap is selected from sodium, potassium or ammonium. More preferably the cation of the soap is sodium or potassium. Fatty acids derived from other suitable oils / fats such as groundnut, soybean, tallow, palm, palm kernel, etc. may also be used in other desired proportions. Such combination of soap with synthetic surfactants is often called a soap-syndet formulation. In a soap syndet formulation soap may be included in 0.1 to 30%, preferably from 1 to 25%, further more preferably from 5 to 20 % by weight of the composition.

[0038] Preferably, the composition may further comprise 0.1 to 40 wt% an amphoteric surfactant, a nonionic surfactant or mixtures thereof. They provide foam boost and improve sensorials of the composition. Preferably, amphoteric surfactants are selected from the class of betaines, sultaines, and amine oxides,. Preferred examples are cocamidopropyl betaine (CAPB), cocamide monoethanolamide (CMEA), cocoamphoacetate and mixtures thereof. When included the composition preferably comprises 0.1 to 20 wt%, more preferably from 1 to 10 wt% amphoteric surfactant.

[0039] Suitable nonionic surfactants include addition products of ethylene oxide and / or propylene oxide with fatty alcohols, fatty acids and fatty amines. Any of the alkoxylated materials of the particular type described hereinafter can be used as the nonionic surfactant. Preferably the nonionic surfactant has an HLB of from about 7 to about 20. Non-ionic surfactant of the polyglucoside type may also be used. If included, the nonionic surfactant is present in an amount from 0.01 to 10 wt.%, more preferably 0.1 to 5 wt.%, based on the total weight of the composition. The pH of composition is preferably in the range of 4.0 to 10.5. Those compositions comprising predominantly synthetic surfactants are preferably in the pH range of 4.5 to 7.0. pH as reported in the present invention is measured as follows. The composition is diluted 1 :1 with deionized water and pH is directly measured by standard pH meter at room temperature (25°C).

[0040] The composition of the invention is preferably in the liquid form in which case water is preferably present in 5 to 95 wt%, more preferably in 40 to 90 wt%.

[0041] Preferably, the composition further comprises water soluble / dispersible polymers. These polymers can be cationic, anionic, amphoteric or nonionic types with molecular weights higher than 100,000 Dalton. They are known to increase the viscosity and stability of liquid cleansing compositions, to enhance in-use and after-use skin sensory feel, and to enhance lather creaminess and lather stability. Such polymers may preferably be used in amounts from 0.1 to 10 wt%, more preferably from 0.1 to 5 wt%, even more preferably from 0.25 to 3 wt% and further more preferably from 0.5 to 2 wt%

[0042] Examples of water soluble / or dispersible polymers include the carbohydrate gums such as cellulose gum, microcrystalline cellulose, cellulose gel, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, sodium carboxymethylcellulose, methyl cellulose, ethyl cellulose, guar gum, gum karaya, gum tragacanth, gum arabic, gum acacia, gum agar, xanthan gum and mixtures thereof; modified and nonmodified starch granules and pregelatinized cold water soluble starch and phosphate starches; emulsion polymers such as Aculyn® 28, Aculyn® 22 or Carbopol® Aqua SF1 ; cationic polymer such as modified polysaccharides including cationic guar available from Rhone Poulenc under the trade name Jaguar® C13S, Jaguar® C14S, Jaguar® C17, or Jaguar® C16; cationic modified cellulose such as LICARE® Polymer JR 30 or JR 40 from Amerchol; N-Hance® 3000, N-Hance® 3196, N-Hance® GPX 215 or N-Hance® GPX 196 from Hercules; synthetic cationic polymer such as Merquat® 100, Merquat® 280, Merquat® 281 and Merquat® 550 sold by Nalco; cationic starches such as StaLok® 100, 200, 300 and 400 sold by Staley Inc.; cationic galactomannans such as Galactasol® 800 series by Henkel, Inc.; Quadrosoft® LM-200; and Polyquaternium-24®; and Polyquaternium-67 from Dow. Also suitable are high molecular weight polyethylene glycols such as Polyox® WSR-205 (PEG 14M), Polyox® WSR-N- 60K (PEG 45), and Polyox® WSR-301 (PEG 90M). Preferably, the composition further comprises one or more skin brightening agents. Preferably, the skin brightening agent may be selected from ammonium lactate, arbutin, azelaic acid, kojic acid, butyl hydroxy anisole, butyl hydroxy toluene, citrate esters, 3 diphenyl propane derivatives, ellagic acid, gluco pyranosyl-1 -ascorbate, gluconic acid, hydroquinone, 4 hydroxyanisole, and linoleic acid. The amount of skin brightening agents that may be included in the composition of the invention depends on its efficacy but generally they are included in 0.01 to 5 wt% of the composition.

[0043] Preferably, the composition further comprises preservatives to protect the composition against the growth of potentially harmful microorganisms. Particularly preferred preservatives include hydantoin derivatives, propionate salts, a variety of quaternary ammonium compounds, phenoxyethanol, imidazolidinyl urea, caprylyl glycol, undecyl alanine, capryloyl glycine, sodium dehydroacetate, sodium benzoate and benzyl alcohol. Preservatives are preferably used in amounts ranging from 0.01 wt% to 2 wt% and more preferably from 0.1 to 1 wt%.

[0044] The composition may further comprise emollients, such as stearyl alcohol, glyceryl monoricinoleate, mink oil, cetyl alcohol, isopropyl isostearate, stearic acid, isobutyl palmitate, isocetyl stearate, oleyl alcohol, isopropyl laurate, hexyl laurate, decyl oleate, octadecan-2-ol, isocetyl alcohol, eicosanyl alcohol, behenyl alcohol, cetyl palmitate, silicone oils such as dimethylpolysiloxane, di-n-butyl sebacate, isopropyl myristate, isopropyl palmitate, isopropyl stearate, butyl stearate, polyethylene glycol, triethylene glycol, lanolin, cocoa butter, shea butter, corn oil, cotton seed oil, olive oil, palm kernel oil, rape seed oil, safflower seed oil, evening primrose oil, soybean oil, sunflower seed oil, avocado oil, sesame seed oil, coconut oil, arachis oil, castor oil, acetylated lanolin alcohols, petroleum jelly, mineral oil, butyl myristate, isostearic acid, palmitic acid, isopropyl linoleate, lauryl lactate, myristyl lactate, decyl oleate, glyceryl oleate, glyceryl monostearate, myristyl myristate. Emollients may be included in 0.1 to 15 wt% preferably 0.1 to 10 wt% of the composition.

[0045] The composition of the invention may also be delivered through a self-foaming composition. A preferred self-foaming composition comprises 2.5 to 10 wt% surfactant which is usually a mixture of a synthetic anionic surfactant and amphoteric surfactant. Synthetic anionic surfactants preferred are of the amino acid class viz. sodium lauroyl glycinate, sodium cocoyl glycinate, sodium lauroyl glutamate, sodium cocoyl glutamate and may also be selected from one or more of sodium lauroyl isethionate, sodium cocoyl isethionate, alpha olefin sulfonate (AOS), or a combination thereof. The amphoteric surfactant may be one or more as listed herein above. Self foaming composition additionally usually comprises a humectant selected from glycerol, propylene glycol, dipropylene glycol, polypropylene glycol, polyethylene glycol, sorbitol, hydroxypropyl sorbitol, hexylene glycol, 1 ,3-butylene glycol, isoprene glycol, 1 ,2,6-hexanetriol, ethoxylated glycerol, propoxylated glycerol, or a combination thereof. It may also comprise an emollient which may be selected from one or more of the compounds listed herein above. Such types of self-foaming compositions are usually free of sulphate.

[0046] The compositions may further comprise a wide range of other optional components e.g. antioxidants, biological additives, buffering agents, colorants, astringents, fragrance, humectants, opacifying agents, conditioners, pH adjusters, skin soothing agents and skin healing agents. The invention will now be illustrated with the help of the following non-limiting examples.

[0047] Examples

[0048] Examples 1-8: Deposition of 12-KSA as compared to 12-HSA on vitro skin;

[0049] Liquid skin cleansing compositions as shown in Table -1 was prepared.

[0050] Table - 1

[0051] Table - 2:

[0052] The deposition of the actives (12HSA / 12KSA) was measured on vitro skin using the procedure as given below:

[0053] Vitro skin was taken and cut into 5x5 cm pieces. It was then pre-wet with 500 iL of water and rubbed for 30 seconds. The excess water was then drained. 0.08 ml of the neat product was then applied and lather was generated for 20 seconds. The lather was retained on the vitro skin for 30 seconds. The vitro skin was then rinsed off with 100-120 ml water for 30 seconds. The vitro skin was then extracted with 10 ml methanol by sonicating for 25 minutes. The concentration of the actives in the extract was then measured using LC-MS analysis. The data is summarized in table - 3 below.

[0054] Table - 3

[0055] *The composition was too viscous to be processed easily and so the deposition could not be measured.

[0056] The data in Table - 3 above indicates that 12KSA deposits much better than 12HSA from a composition used to wash the substrate.

[0057] Example 1 , 5-6, 9-10: Rheology of various compositions

[0058] Examples 1 , 5-6, 9-10 containing 12HSA or 12KSA or a combination (as described in Table -4 below) in a composition of Table - 1 were prepared. These samples were then taken and the rheology measured at two shear rates (0 s'1and 1 s'1). The procedure used to measure the viscosity at these shear rates is as given below:

[0059] The viscosities of the examples were measured by a Cone / Plate Anton Paar viscometer. The cone used was CP5 which has a diameter of 50 mm and 0.5° angle. The viscosity was measured with a shear ramp in which the samples were subjected to increasing shear rate, and sample viscosity was observed as a function of shear rate. All experiments were conducted at 25°C

[0060] The data is summarized in table - 4.

[0061] Table - 4: The data in 4 indicates that composition comprising 12HSA thickens inordinately on increasing the concentration (see Example 9,1). On the other hand, compositions comprising 12KSA do not exhibit such behaviour. A combination of 12HSA and 12KSA in the composition within the specified ratio (Example 10) gives the desired viscosity such that the composition is easy to pour and deliver from a bottle. The data in Table - 3 and Table -4 taken together indicate that the desired deposition of actives from a wash off composition is achieved through incorporation of sufficient amounts of 12KSA while the desired viscosity to ensure pourability is met when 12HSA and 12KSA are combined in a specified ratio.

Claims

Claims1. A personal cleansing composition comprising:(i) hydroxystearic acid;(ii) 0.05 to 10 wt% ketostearic acid; and(iii) 3.0 to 80 wt% synthetic anionic surfactant; wherein the weight ratio of hydroxystearic acid to ketostearic acid is in the range of 15:1 to 1 :500.

2. The composition as claimed in claim 1 wherein the composition comprises from 0.05 to 5 wt% ketostearic acid.

3. The composition as claimed in claims 1 or 2 wherein the hydroxystearic acid is selected from 8- hydroxy stearic acid, 10- hydroxy stearic acid, 12-hydroxystearic acid, trihydroxystearin, trihydroxystearic acid or mixtures thereof.

4. The composition as claimed in any one of the preceding claims wherein the composition comprises from 0.05 to 10 wt% hydroxystearic acid.

5. The composition as claimed in any one of the preceding claims wherein the ketostearic acid is selected from 7-ketostearic acid, 9-ketostearic acid, 10-ketostearic acid, 12- ketostearic acid or mixtures thereof.

6. The composition as claimed in any one of the preceding claims wherein the total amount of hydroxystearic acid and ketostearic acid is in the range of 0.1 to 10 wt%.

7. The composition as claimed in any one of the preceding claims wherein the synthetic anionic surfactant, isethionates, taurates, glycinates, alkyl sulfates, alkyl ether sulphates, succinates, sulphosuccinates, amphoacetates, sarconsinates, glutamates, a-olefin sulphonates, lactylates, methyl ester sulfonates and mixtures thereof.

8. The composition as claimed in any one of the preceding claims further comprising 0.1 to 40 wt% an amphoteric surfactant, nonionic surfactant or mixtures thereof.

9. The composition as claimed in any one of the preceding claims wherein the pH of the composition is in the range 4.0 to 10.5.

10. The composition as claimed in any one of the preceding claims, wherein the composition is in liquid form.

11. The composition as claimed in claim 10 comprising 5 to 95 wt% water.

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