A skin cleansing composition

Abstract

The present invention relates to a skin cleansing composition, particularly a skin cleansing composition that provides improved antimicrobial benefit. The skin cleansing composition comprises N-acyl (R-C=O) substituted diamine wherein R is alkyl group of 1 to 8, preferably 1 to 4, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11; and the composition is substantially free of a bleaching agent,.

Description

[0001] A SKIN CLEANSING COMPOSITION

[0002] Field of the Invention

[0003] The present invention relates to a skin cleansing composition. Particularly, the present invention relates to a skin cleansing composition that provides improved antimicrobial benefit especially in compositions which are substantially free of bleaching agents.

[0004] Background of the Invention

[0005] Microbes e.g. bacteria, tend to colonize on surfaces e.g. human skin. Some of these microbes may trigger harmful effects if they enter the human system e.g. through cuts in the skin and through the act of ingestion. Therefore, there is a general desire to maintain hygiene by getting rid of such harmful microbes. For example, people tend to wash hands with a skin cleansing composition from time to time to help maintain hygiene.

[0006] Several skin cleansing compositions e.g. a handwash I bodywash composition, are known in the art that provide antimicrobial benefit. Such skin cleansing compositions are available in the form of a solid e.g. a bar such as soap bar; and in the form of a liquid e.g. a liquid handwash I bodywash. Generally, antimicrobial benefit delivered by such skin cleansing compositions is delivered by one or more actives that may be present in such skin cleansing compositions. For example, skin cleansing composition comprising an antibacterial active e.g. triclosan, is known in the art. Bleaching agents like peroxides also deliver good antibacterial efficacy. Peroxides and similar bleaching agents are generally oxidizing agents which are considered by many to be harsh on the skin.

[0007] In light of the above, people tend to look forward to newer technologies that provide improved antimicrobial benefit, yet be mild on skin. Providing mild skin cleansing compositions that provide improved antimicrobial benefit is therefore still a topic of interest.

[0008] It has now been found that an N-acyl substituted diamine provides antimicrobial benefit when included in a skin cleansing composition having select pH. N-acyl substituted diamine compound like tetra-acetyl ethylenediamine (TAED) have been known and used extensively in bleach containing laundry detergent composition as a bleach activator. Such bleach activators are generally included together with a bleaching agent like peroxides in laundry detergent compositions. WO2016 / 204943 (The Dial Corp) discloses a cosmetic, detergent and surface cleansing composition which includes a biosurfactant flavolipid which is considered mild in comparison to conventional detergent actives. It discloses that bleaching agents like percarbonate can be used in detergent compositions along with bleach activating agents like TAED.

[0009] CN 106281757 discloses a broad spectrum antiseptic liquid detergent composed of the following components in parts by weight: C12 benzene sulphonamide of 50% acid sodium solution 35 parts; Chinese medicine 2 parts; polyethylene glycol 10 parts; tetraacetyl ethylene diamine 6 parts; fat polyvinyl ether 15 parts; phosphorus acid trisodium 1 part; polystyrene latex 1 part; essence 0.02 parts; citric acid 0.06 parts; pigment 0.02 parts and Water 70 parts.

[0010] The present invention concerns skin cleaning compositions that are substantially free of such bleaching agents and yet are able to achieve high antimicrobial efficacy. This has been achieved through use of N-acyl substituted diamine compound in the absence of a bleaching agent. This antimicrobial effect is further improved when N-acyl substituted amine is combined with select potassium salts.

[0011] Summary of the Invention

[0012] In a first aspect, the present invention relates to a skin cleansing composition comprising from 0.1 to 4 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11 ; wherein the composition is substantially free of a bleaching agent.

[0013] In a second aspect, the present invention relates to a method of providing antimicrobial benefit to a surface comprising the steps: a. applying to the surface the composition of the first aspect; and b. rinsing the surface within 5 minutes of carrying out step a.

[0014] In a third aspect, the present invention relates to use of the composition of the first aspect for obtaining antimicrobial benefit.

[0015] Detailed Description of the Invention 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.

[0016] For the purpose of the present invention, the terms ‘antimicrobial benefit’ or ‘antimicrobial effect’ or ‘antimicrobial efficacy’, may be used interchangeably and they denote the same meaning. Preferably, ‘antimicrobial benefit’ or ‘antimicrobial effect’ or ‘antimicrobial efficacy’ means reduction in number of microbes e.g. bacteria, fungi and viruses. Such antimicrobial effect is obtained when the composition of the present invention is preferably applied on to a surface that may be an inanimate or animate surface; and a step of rinsing the surface is carried out within 5 minutes from the step of applying the composition. More preferably, the composition is applied to an animate substrate e.g. human skin. ‘Skin’ as used herein, preferably means to include skin on any part of the body e.g. face, neck, chest, back, arms, underarms, hands, legs, buttocks and scalp.

[0017] The skin cleansing agent is substantially free of a bleaching agent. Thus, the composition preferably comprises less than 1 wt%, more preferably less than 0.1 wt%, even more preferably less than 0.05 wt%, and further more preferably less than 0.01 wt% of bleaching agent. Still more preferably, the bleaching agent is only present in technically irrelevant amounts and ideally bleaching agent is absent from the composition.

[0018] Bleaching agent is a compound which can cause a bleaching action on a surface. Such agents are generally of the chlorine or peroxide type, preferably peroxide type. By a peroxide type bleaching agent is meant one which comprises a source of hydrogen peroxide. Compounds of this class include perborate, percarbonate, peracid and persulphate salts. They could also be of the persilicate or perphosphate class. The bleaching agent is generally an alkali salt preferably a sodium salt.

[0019] A skin cleansing composition according to the present invention (the composition) comprises from 0.1 to 4 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11 ; wherein the composition is substantially free of a bleaching agent.

[0020] When used on a surface, an animate or an inanimate surface, preferably animate surface, the composition provides antimicrobial effect. Preferably, the antimicrobial effect is obtained in time frames as short as less than 5 minutes, e.g. 1 minute, 30 seconds and 15 seconds.

[0021] N-acyl substituted diamine

[0022] The composition comprises N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of linear or branched, 1 to 8, preferably 1 to 4, carbon atoms. Examples of the N-acyl substituted diamine suitable for use in the present invention include tetra-acetyl ethylenediamine (TAED), tri-acetyl ethylene diamine, diacetyl ethylenediamine (DAED) and mixtures thereof. Preferably, the N-acyl substituted diamine is non-volatile.

[0023] The composition comprises from 0.1 to 4 wt%, preferably from 0.5 to 3 wt% of N-acyl substituted diamine.

[0024] It has been found that the N-acyl substituted diamine provides antimicrobial benefit when used in a skin cleansing composition having pH from 4 to 11.

[0025] Potassium salt

[0026] Preferably, the composition further comprises a potassium salt selected from potassium chloride, potassium sulfate, potassium nitrate, potassium sorbate, potassium carbonate, potassium acetate, potassium hydrogen phosphate, potassium salt of a fatty acid having 8 to 22 carbon atoms and mixtures thereof. More preferably, a potassium salt is selected from potassium chloride, potassium sulfate, potassium nitrate and potassium salt of a fatty acid having 8 to 22 carbon atoms and mixtures thereof. Examples of potassium salt of a fatty acid having 8 to 22 carbon atoms include potassium laurate, potassium myristate, potassium palmitate, potassium stearate. Even more preferably, a potassium salt is selected from potassium chloride, potassium sulfate, and potassium laurate and mixtures thereof. Preferably, the composition comprises a potassium salt from 0.1 to 15 wt%, more preferably from 1 to 13 wt%, even more preferably from 2 to 12 wt%, further more preferably from 3 to 10 wt%, yet more preferably from 5 to 8 wt% potassium salt.

[0027] It has been found that a potassium salt when used in combination with N-acyl substituted diamine described above, improved antimicrobial benefit was obtained.

[0028] Surfactant

[0029] Preferably, the composition further comprises a surfactant. Preferably, the surfactant is selected from an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant and mixtures thereof. More preferably, the surfactant is selected from an anionic surfactant, an amphoteric surfactant and mixtures thereof. Further more preferably the surfactant is an anionic surfactant. Preferred anionic surfactant is soap.

[0030] Anionic surfactant

[0031] Preferably, an anionic surfactant selected is selected from one or more synthetic anionic surfactant. Preferably, a synthetic anionic surfactant is selected from alkyl sulfate (AS), alkyl ether sulfate (AES), alpha olefin sulfonate (AOS) and mixtures thereof. Examples of AS that may be used as anionic surfactant in the composition include sodium lauryl sulfate (SLS), sodium myristyl sulfate, sodium palmityl sulfate and mixtures thereof. Examples of AES that may be used as an anionic surfactant include anionic surfactants of the general formula:

[0032] Ri-(OR’)n-O-SO3' M+, wherein:

[0033] Ri is saturated or unsaturated Cs-Ci6, preferably C12-C14 alkyl chain; preferably, R1 is a saturated Cs-Ci6, more preferably a saturated C12-C14 alkyl chain;

[0034] 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 and further more preferably from 1 to 3,

[0035] M+is a suitable cation which provides charge neutrality, preferably sodium, calcium, potassium, or magnesium, more preferably a sodium cation.

[0036] Examples of AES that may be used as anionic surfactant 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. Alternatively, but preferably, anionic surfactant may be selected from sodium salts of fatty acids having 8 to 22 carbon atoms e.g. sodium laurate, sodium myristate, sodium palmitate, sodium stearate and mixtures thereof.

[0037] It will be understood that if used, potassium salt of a fatty acid having 8 to 22 carbon atoms is used as potassium salt in the composition, i.e. it is not used as a soap. In other words, if potassium salt of a fatty acid having 8 to 22 carbon atoms e.g. potassium laurate, is used in the composition, then an anionic surfactant may either be chosen from synthetic anionic surfactants or from non-potassium salts of fatty acids having 8 to 22 carbon atoms or mixtures thereof as described above. In other words, by use of the word "soap” it is meant as per the present invention that it is any soap other than potassium laurate.

[0038] Nonionic surfactant

[0039] Preferably, nonionic surfactant may be selected from: fatty alcohol ethoxylates with saturated carbon chain and having HLB higher than 15.5 e.g. Brij® 35 (also known as Brij® L23), fatty alcohol ethoxylates with unsaturated carbon chain with HLB higher than 12, e.g. Brij® 97 and Brij® 99, alkyl phenol ethoxylates having HLB higher than 15; e.g. Triton™ X 405, polyoxyethylene sorbitan alkyl esters with saturated C12 to C16 carbon chain and having HLB higher than 12; e.g. Tween® 20, polyoxyethylene sorbitan alkyl esters with unsaturated C18 carbon chain and having HLB higher than 9; e.g. Tween® 80, Tween® 81 ; and Tween® 85; and mixtures thereof.

[0040] Amphoteric surfactant

[0041] Amphoteric surfactants provide improved foam when added in the composition. Preferably, amphoteric surfactants are selected from cocamidopropyl betaine (CAPB), cocamide monoethanolamide (CMEA), cocoamphoacetate and mixtures thereof.

[0042] Cationic surfactant

[0043] Preferably, cationic surfactants may be selected from cetyltrimethylammonium chloride, behenyltrimethylammonium chloride, cetylpyridinium chloride, tetramethylammonium chloride, tetraethylammonium chloride, octyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octyldimethylbenzylammonium chloride, decyldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride, didodecyldimethylammonium chloride, dioctadecyldimethylammonium chloride, tallowtrimethylammonium chloride, dihydrogenated tallow dimethyl ammonium chloride (eg, Arquad 2HT / 75 from Akzo Nobel), cocotrimethylammonium chloride, PEG-2-oleammonium chloride and the corresponding hydroxides thereof. Further suitable cationic surfactants include those materials having the CTFA designations Quaternium-5, Quaternium-31 and Quaternium- 18. Mixtures of any of the foregoing materials may also be suitable. A particularly useful cationic surfactant is cetyltrimethylammonium chloride, available commercially, for example as GENAMIN® CTAC. Another particularly useful cationic surfactant is behenyltrimethylammonium chloride, available commercially, for example as GENAMIN® KDMP. Yet another preferred cationic surfactant is stearamidopropyl dimethylamine.

[0044] The composition comprises from 1 to 85 wt% surfactant, preferably from 5 to 80 wt%, more preferably from 10 to 75 wt%, even more preferably from 15 to 70 wt%, yet more preferably from 25 to 66 wt%, still more preferably from 35 to 60 wt% and still further more preferably from 40 to 55 wt% surfactant.

[0045] £H

[0046] The pH of the composition is in the range from 4 to 11 , preferably from 4.5 to 10.5, even more preferably from 5.0 to 10.0, further more preferably from 5.5 to 9.5, still more preferably from 6.0 to 9.0, yet more preferably from 6.5 to 8.5 and still more preferably from 7.0 to 8.0. For example, the pH of the composition may be in the range 9.6 to 10.2. The pH of the composition may be adjusted using suitable pH adjusting agents e.g. sodium hydroxide and sodium bicarbonate.

[0047] If the composition is in liquid form, then preferably, pH of the composition is in the range 4 to 11 when measured before dilution or preferably after diluting the composition to 50% concentration, at 25 to 35°C.

[0048] If the composition is in solid form, then preferably, pH of the composition is in the range from 4 to 11 when measured using 1 to 8% e.g. 8%, aqueous solution of the composition in demineralized water, at temperature 25 to 35°C. The pH ranges as described above are generally considered to be skin friendly. Format of the composition

[0049] Preferably, the composition is in liquid form or in solid form. More preferably, the composition is in solid form e.g. a bar. Even more preferably, the composition is in the form of a soap bar.

[0050] Accordingly, the composition is preferably a liquid skin cleansing composition comprising from 0.1 to 15 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, preferably 1 to 4, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11 , preferably from 4 to 7.

[0051] Alternatively but preferably, the composition is a solid skin cleansing composition comprising from 0.1 to 15 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, preferably 1 to 4, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11 .

[0052] More preferably, the composition is a soap bar composition comprising from 0.1 to 15 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, preferably 1 to 4, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 8 to 11.

[0053] Further more preferably, the composition is a soap bar composition comprising: from 0.1 to 15 wt% N-acyl substituted diamine selected from di-acetyl ethylenediamine, tetra-acetyl ethylenediamine and mixtures thereof; and from 0.1 to 15 wt% one or more potassium salt descried above, wherein the pH of the composition is in the range from 8 to 11.

[0054] In such case, one or more anionic surfactant in the composition is preferably selected from a synthetic anionic surfactant or a non-potassium salt of a fatty acid having 8 to 22 carbon atoms, e.g. sodium laurate, sodium myristate, sodium palmitate, sodium stearate.

[0055] Structurants

[0056] Preferably, the composition comprises a structurant. Preferably, a structurant is selected from silica, talc, calcite, pumice, tricalcium phosphate, chalk, fullers earth, kaolin, starch, gums, colloidal silica, sodium polyacrylate, tetra alkyl and / or trialkyl aryl ammonium smectites, chemically modified magnesium aluminium silicate, organically modified montmorillonite clay, hydrated aluminium silicate, fumed silica, carboxyvinyl polymer, sodium carboxymethyl cellulose, ethylene glycol monostearate and mixtures thereof. Talc is a magnesium silicate mineral material, with a sheet silicate structure and a composition of Mg3Si4(OH)22 and may be available in the hydrated form. It has a plate-like morphology, and is essentially oleophilic / hydrophobic, i.e. , it is wetted by oil rather than water.

[0057] Starch may be used directly or modified during the process of making the bar composition such that the starch becomes gelatinized, either partially or fully gelatinized. Another suitable starch is pre-gelatinized which is starch that has been gelatinized before it is added as an ingredient in the present bar compositions. Various forms are available that will gel at different temperatures, e.g., cold water dispersible starch. An example of pre-gelatinized starch available commercially, is FARMAL® CS 3400.

[0058] Preferably the composition comprises structurants in an amount ranging from 1 to 50 wt%, more preferably from 3 to 45 wt%, even more preferably from 10 to 30 wt and further more preferably from 15 to 25 wt%.

[0059] Polymers

[0060] Preferably, the composition further comprises water soluble polymers. Preferably, such polymers are selected from polyvinyl alcohol, polyvinyl pyrrolidone, sodium carboxymethylcellulose, polyethylene glycol, methyl cellulose, hydroxypropyl methyl cellulose and mixtures thereof.

[0061] Preferably, the composition comprises from 1 to 20 wt%, more preferably from 3 to 17 wt%, even more preferably from 5 to 15 wt%, further more preferably from 7 to 13 wt% and still more preferably from 9 to 12 wt% water soluble polymer.

[0062] Such polymer may be added in the composition mix or may be used to coat the composition. For example, if the composition is in the form of a bar or a tablet, such polymers may form an outer water-soluble coating on such bars or tablets.

[0063] If the composition is formulated in the form of a bar, then it preferably comprises a polyhydric alcohol (also called polyol) or mixture of polyols. Polyol is a term used herein to designate a compound having multiple hydroxyl groups (at least two, preferably at least three) which is highly water soluble, preferably freely soluble, in water. Many types of polyols are available including relatively low molecular weight short chain polyhydroxy compounds such as glycerol and propylene glycol; sugars such as sorbitol, manitol, sucrose and glucose; modified carbohydrates such as hydrolyzed starch, dextrin and maltodextrin, and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG). Especially preferred polyols are glycerol, sorbitol and their mixtures. Most preferred polyol is glycerol. If the composition is formulated as a bar then preferably it comprises from 0 to 8 wt%, more preferably from 1 to 7.5 wt%, even more preferably from 2 to 5 wt% polyol. Preferably, the composition further comprises an opacifier. Examples of opacifiers include titanium dioxide, zinc oxide and the like. An alternative opacifying agent is zinc stearate.

[0064] A preferred bar may additionally include up to 30 wt% benefit agents. Preferred benefit agents include moisturizers, emollients, sunscreens and anti-ageing compounds. These agents may be added at an appropriate step during the process of making the composition.

[0065] The composition may further comprise one or more of the following ingredients:

[0066] The composition may preferably further comprise a skin-lightening agent 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, glycolic acid, hydroquinone, 4 hydroxyanisole, linoleic acid, magnesium ascorbyl phosphate, 2,4 resorcinol derivatives, 3,5 resorcinol derivatives, vitamins like vitamin B6, vitamin B12, vitamin C, vitamin A, resorcinol derivatives and mixtures thereof.

[0067] If the composition is formulated in the form of a bar then it preferably comprises water in an amount from 10 to 20 wt%, more preferably from 14 to 18 wt%. Alternatively, if the composition is formulated in the form of a liquid, then the composition preferably comprises from 40 to 90 wt% water, more preferably 60 to 85 wt% water.

[0068] The composition may preferably further comprise 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, sodium dehydroacetate and benzyl alcohol. Preservatives are preferably used in amounts ranging from 0.01 wt% to 2 wt%.

[0069] Diluents other than water can include liquid or solid emollients, solvents, humectants, thickeners and powders. Examples of each of these types of vehicles which can be used singly or as mixtures of one or more vehicles, are as follows:

[0070] 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, 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, myristyl myristate.

[0071] Further, the composition preferably comprises other optional ingredients like anti-oxidants, perfumes, polymers, chelating agents, colourants, deodorants, dyes, emollients, moisturizers, enzymes, foam boosters, lathering agents, skin conditioners, pH adjusters and stabilizers may be added in suitable amounts. Preferably, these ingredients are added after the saponification step. Sodium metabisulphite, ethylene diamine tetra acetic acid (EDTA), borax or ethylene hydroxy diphosphonic acid (EHDP) are preferably added to the formulation. Such ingredients may be present in an amount from 0 to 7 wt%, more preferably from 1 to 5 wt% and even more preferably from 2 to 4 wt% in the composition.

[0072] In a second aspect, the present invention relates to a method of providing antimicrobial benefit comprising the steps: a. applying to a surface the composition according to the first aspect; and b. rinsing the surface within 5 minutes of carrying out the step a.

[0073] Step a involves applying the composition of the first aspect on to a surface. The surface is preferably an inanimate or animate surface. More preferably, the surface is an animate surface e.g. human skin. ‘Skin’ as used herein, preferably means to include skin on any part of the body e.g. face, neck, chest, back, arms, underarms, hands, legs, buttocks and scalp. Step a is preferably carried out where a user applies the composition of the first aspect, on to a surface along with water in an amount sufficient to create lather.

[0074] The method comprises an additional step, step b, where the surface on to which the composition is applied, is rinsed with water to remove the composition from the surface. Step (b) is carried out within less than 5 minutes, more preferably within less than 3 minutes, even more preferably within less than 1 minute and furthermore preferably within less than 35 seconds e.g. 10 to 30 seconds, after step a. When the method is carried out as described in the second aspect, antimicrobial benefit is obtained, i.e. microbes e.g. bacteria, are reduced from the surface on to which the composition was so applied. Preferably, the method is non-therapeutic and / or cosmetic in nature.

[0075] In a third aspect, the present invention relates to use of the composition of the first aspect for obtaining antimicrobial benefit. Preferably, the use is non-therapeutic.

[0076] In a fourth aspect, the present invention relates to use of N-acyl substituted diamine in a composition which is substantially free of a bleaching agent, wherein the pH of the composition is in the range from 4 to 11 for obtaining antimicrobial benefit. Preferably, the use is non- therapeutic.

[0077] In a fifth aspect, the present invention relates to use of a combination of N-acyl substituted diamine and a potassium salt in a composition which is substantially free of a bleaching agent, having pH in the range 4 to 11 , for obtaining antimicrobial benefit. Preferably, the use is non- therapeutic.

[0078] The invention is described further through the non-limiting examples below:

[0079] Examples

[0080] Protocols

[0081] Skin cleansing compositions in the form of soap bars (shown in table 2) were prepared as follows:

[0082] Soap noodles (as shown in table 1) were made using oils e.g. palm oil (PO) and palm kernel oil (PKO) in required ratio (e.g. 80:20; PO:PKO) through saponification reaction and was processed into noodles with water, glycerin, electrolyte such as sodium chloride, preservative like EDTA, EHDP and / or fillers. Alternatively, soap noodles may be made using the oils in ratio such as 70:30, 85:15, 90:10, PO:PKO. The saponification was done through either Crutcher or continuous saponification tank or plough shear mixer route. The end mass was cooled and extruded into soap noodles. This soap noodles with required PKO value (10, 20, 25,30 and 40) with an IV (Iodine value) range of 30 to 45 was made in-house.

[0083] The soap noodles were crushed in sigma mixer for up to 5 minutes. After complete crushing of the noodles, solid ingredients such as soda ash and talc were added and mixed. Actives e.g. TAED, was added at this stage and mixed followed by addition of polymer and colorants, if required, and mixed for up to 3 minutes. Alternatively, colorants may be added during crushing of noodles. Lastly, perfume was added and mixing was carried out for up to 3 min. Post this mixing, the mass was processed through triple roll mill and was plodded through plodder to get the final bar and stamped, as necessary.

[0084] Antimicrobial Effect:

[0085] The antimicrobial effect was assessed for compositions outlined in table 2 below using the ASTM 2783, a standard test method for assessment of antimicrobial activity for water miscible compounds using a Time -Kill procedure. Escherichia coli (ATCC 10536) and Staphylococcus aureus (ATCC 6538) were used as the test organisms.

[0086] Preparation of working culture of the test organisms: Approximately 48 hours prior to testing, a sterile tube of Tryptic Soy Broth (TSB) was inoculated from a glycerol stock containing the challenge (test) microorganism. The broth culture was incubated at 35 ± 2°C for 24 hours.

[0087] Approximately 24 hours prior to testing, the broth culture was inoculated onto the surface of sterile Tryptic Soy Agar (TSA) & incubated at 35 ± 2°C for approximately 24 hours.

[0088] Bacterial Challenge Test Suspensions and Validation test Suspension (To be prepared just before use): A suspension of the challenge microorganism was prepared in sterile 0.9% saline and adjusting the optical density at 620 nm to achieve a challenge suspension concentration of approximately 7 x 108cfu / mL to 9 x 108cfu / mL. A challenge suspension was prepared for each replicate of testing. Each challenge suspension was used within 2 hours of preparation and kept at 25 ± 1°C. A neutralization challenge test suspension containing approximately 3000-10000 cfu / mL was prepared in sterile saline by diluting the challenge microorganism.

[0089] Preparation of 8% soap slurry:

[0090] Soap bar samples were finely grated and weighed 8 g into a sterile bottle. 92 mL of sterile distilled water (DW) was pre warmed at 50 ± 1°C and added 8 g of above soap sample and mixed using submersible magnetic stirrer and kept for 25 to 30 minutes to make an 8% soap slurry. After 25 to 30 minutes, 10 mL sample aliquot was transferred to a vial placed at 40 ± 1°C and kept for 3 to 5 minutes for equilibration and mixed using submersible magnetic stirrer. Evaluation of bacterial reduction efficacy:

[0091] 10 mL of test solution was placed in a vial and kept in water bath maintained at test temperature for 3 to 5 minutes to equilibrate. A 0.1 mL aliquot of the challenge suspension was transferred to the vial containing test solution and mixed thoroughly using submersible magnetic stirrer. The challenge suspension was exposed to the test solution for required contact time e.g. less 5 minutes e.g. 30 seconds, using a calibrated minute and second timer. Upon elapse of contact time, 1 mL aliquot was transferred from the vial containing the test solution / challenge suspension to a test tube containing 9.0 mL of pre-validated neutralizer and mixed thoroughly using a vortex mixer. Additional ten-fold dilutions were prepared by transferring 1 mL aliquots into 9 mL of neutralizer (1 O’2, 10’3, 10'4and 10'5). 1.0 mL aliquots of each dilution frornlO'1to10-5were plated using TSA in duplicate using pour plate technique. The plates were incubated as per given incubation conditions.

[0092] The log reduction for each challenge suspension attributable to the test solution at each timed exposure is calculated for each replicate as follows:

[0093] Log Reduction = Log average (NC) - Logwaverage (Pex), where NC = Number Control cfu / mL Population and Pex= Post exposure population cfu / mL

[0094] Table 1 : Noodle Composition

[0095] Table 2: Soap bars and antimicrobial effect obtained

[0096] Antimicrobial effect obtained using compositions according to the invention (Examples 1 to 8) and controls (A and B) are outlined below:

[0097] ’Polymer, colorant and fragrance; *S. aureus ATCC 6538; contact time = 30 seconds

Claims

Claims1. A skin cleansing composition comprising from 0.1 to 4 wt% N-acyl (R-C=O) substituted diamine wherein R is an alkyl group of 1 to 8, linear or branched, carbon atoms; and wherein the pH of the composition is in the range from 4 to 11 ; wherein the composition is substantially free of a bleaching agent.

2. The composition as claimed in claim 1 wherein the N-acyl substituted diamine is selected from di-acetyl ethylenediamine, tri-acetyl ethylenediamine, tetra-acetyl ethylenediamine and mixtures thereof.

3. The composition as claimed in any one of claims 1 or 2 wherein the N-acyl substituted diamine is tetra-acetyl ethylenediamine.

4. The composition as claimed in any one of claims 1 to 3 wherein the composition further comprises from 0.1 to 15 wt% potassium salt.

5. The composition as claimed in claim 4 wherein the potassium salt is selected from potassium chloride, potassium sulfate, potassium nitrate, potassium sorbate, potassium carbonate, potassium acetate, potassium hydrogen phosphate, potassium salt of a fatty acid having 8 to 22 carbon atoms and mixtures thereof.

6. The composition as claimed in claim 5 wherein the potassium salt is selected from potassium chloride, potassium sulfate, potassium nitrate and potassium salt of a fatty acid having 8 to 22 carbon atoms and mixtures thereof.

7. The composition as claimed in claim 6 wherein the potassium salt is selected from potassium chloride, potassium sulfate, and potassium laurate and mixtures thereof.

8. The composition as claimed in any one of claims 1 to 7 wherein the composition further comprises 1 to 85 wt% surfactant.

9. The composition as claimed in claim 8 wherein the surfactant is soap.

10. The composition as claimed in any one of claims 1 to 9 wherein the pH of the composition is in the range from 8 to 10.

11. The composition as claimed in any one of claims 1 to 10 wherein the composition is in solid form.

12. A method of providing antimicrobial benefit to a surface comprising the steps: a. applying to the surface the composition as claimed in any one of claims 1 to 11 ; and b. rinsing the surface within 5 minutes of carrying out step a.

13. Use of composition as claimed in any one of claims 1 to 11 for obtaining antimicrobial benefit.

14. Use of N-acyl substituted diamine in a composition which is substantially free of a bleaching agent, wherein the pH of the composition is in the range from 4 to 11 , for obtaining antimicrobial benefit.

15. Use of a combination of N-acyl substituted diamine and a potassium salt in a composition which is substantially free of a bleaching agent, having pH in the range from 4 to 11, for obtaining antimicrobial benefit.

Images