Soap compositions with improved antimicrobial efficacy

Abstract

Disclosed is a soap bar composition comprising: 25 to 65 wt% total fatty matter, 0.01 to 3.5 wt% electrolyte, 0.01 to 2 wt% antimicrobial efficacy boosting agent, 3 to 45 wt% starch; and 10 to 30 wt% water; wherein the antimicrobial efficacy boosting agent is a different compound than the electrolyte.

Description

[0001] SOAP COMPOSITIONS WITH IMPROVED ANTIMICROBIAL EFFICACY

[0002] Field of the invention

[0003] The present invention relates to soap bar compositions. More particularly the present invention relates to soap bar compositions with improved antimicrobial efficacy.

[0004] Background of the invention

[0005] Conventional cleansing bars based on soap for personal washing usually contain over about 70% by weight total fatty matter, the remainder being water (about 10-20%) and other ingredients such as colour, perfume, preservatives, etc. Structurants are also present in such compositions in amounts, which replace some of the soap in the bar while retaining the desired hardness of the bar. A few known structurants include starch, kaolin and talc.

[0006] Hard non-milled cleansing bars containing moisture of less than 35% are also available. These bars have a TFM of about 30- 65%. The reduction in TFM has usually been achieved by the use of insoluble particulate materials and / or soluble silicates. Milled bars generally have a water content about 8-15%, and the hard non-milled bars have a water content of about 20-35%.

[0007] It is important to deliver sensory properties such as lather and skin feel, preferably by incorporating benefit agents in the formulation without altering the process, ability and physical properties of the bar.

[0008] Currently most of the extruded cleansing bars contain some amount of soluble oil soap content which helps for lathering, and cleansing and insoluble oil soap content for structuring the cleansing bar. Normally any soap composition contains 5% to 20% of soluble soap and rest is insoluble soap. Essentially any cleansing bar will have 60 to 95% of insoluble soap used only for structuring the cleansing bar which does not play any role in cleansing. There are some cleansing bars with 40 to 50 TFM where TFM is compensated by skin beneficiary agents, moisturizers etc. Overall normal soap contains 60-70% of soap which only helps for structuring cleansing bar. Generally cast melt cleansing bars available in the market range from with 40-60 TFM. Several bacteria prefer to live and multiply on the human skin. Some of these bacteria are known to cause body odour, pimples and acne. There is some evidence in the prior art to suggest that some of these conditions aggravate in a hot and humid climate. It is known that soaps, i.e. salts of fatty acids, per-se, have antimicrobial properties.

[0009] The increasing demand for vegetable oils, such as palm oil, (one of the main sources of oils and fatty acids used by soap manufacturers), and consequent soaring prices has led to severe constraints on the sustainability of the soaps and detergents Industry, as it is becoming increasingly difficult to provide high TFM soaps at a competitive cost, while still making reasonable profits.

[0010] As a result, the trend is towards lower TFM soaps, being a cost-effective measure. However, lowering of TFM has a direct and negative effect on the antimicrobial or antibacterial property of the soap compositions.

[0011] Therefore, there is a need to have low TFM cleansing bars in which lowering of TFM does not compromise on the antimicrobial or antibacterial property of the soap compositions.

[0012] WO 03 / 010273 A1 (Unilever) discloses a transparent soap bar comprising: (iii) from 30 to 60 percent by weight of the soap bar of total fatty matter wherein from 1 to 15 percent by weight is the salt of 12-hydroxystearic acid or a precursor thereof; (iv) from 20 to 50 percent by weight of the soap bar of at least one polyhydric alcohol; and (iii) water. There is no mention of antimicrobial properties of the bar.

[0013] TW341598 (P&G, 1998) relates to a transparent cast molded personal cleansing soap bar. The invention however only demonstrates higher TFM soaps with the desired hardness. There is no mention of antimicrobial properties of the bar.

[0014] Cleansing compositions which show antimicrobial action but which at the same time are mild and gentle to the skin are generally difficult to formulate.

[0015] There is also a need to have a low TFM cleansing bar which has antimicrobial properties.

[0016] There still is an unmet need for antibacterial cleansing bar having relatively lower TFM and relatively lower levels of antimicrobial actives. There is also a need to provide cleansing bar compositions having relatively lower TFM, which exhibit relatively high antimicrobial activity.

[0017] Summary of the invention

[0018] First aspect of the present invention provides a soap bar composition comprising: a. 25 to 65 wt% total fatty matter; b. 0.01 to 3.5 wt% electrolyte; c. 0.01 to 2 wt% antimicrobial efficacy boosting agent selected from: i. Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or ii. Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof; d. 3 to 45 wt% starch; and e. 10 to 30 wt% water; wherein the antimicrobial efficacy boosting agent under (c) is a different compound than the electrolyte under (b).

[0019] Second aspect of the present invention provides a process for preparing a soap composition of the first aspect, comprising, i) saponifying a fatty matter with an alkali to produce a saponified mass; ii) adding 3 to 45 wt% starch by weight of the resulting soap bar composition and water to obtain a soap mass to result in a soap composition; and iii) optionally extruding the soap mass resulting from step (ii) to obtain the soap bar according to the first aspect; wherein the antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof, is added at step (i) or (ii); and wherein the electrolyte is added at step (i) or (ii).

[0020] Third aspect of the present invention provides use of starch and an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium, in a soap bar comprising 10 to 30 wt% water, for providing enhanced antimicrobial efficacy as compared to a soap bar without an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium.

[0021] As used herein the term “comprising” encompasses the terms “consisting essentially of” and “consisting of”. Where the term “comprising” is used, the listed steps or options need not be exhaustive. Unless otherwise specified, numerical ranges expressed in the format "from x to y" are understood to include x and y. In specifying any range of values or amounts, any particular upper value or amount can be associated with any particular lower value or amount. Except in the examples and comparative experiments, or where otherwise explicitly indicated, all numbers are to be understood as modified by the word “about”. All percentages and ratios contained herein are calculated by weight unless otherwise indicated. As used herein, the indefinite article “a” or “an” and its corresponding definite article “the” means at least one, or one or more, unless specified otherwise. The various features of the present invention referred to in individual sections above apply, as appropriate, to other sections mutatis mutandis. Consequently, features specified in one section may be combined with features specified in other sections as appropriate. Any section headings are added only for convenience and are not intended to limit the disclosure in any way. The invention is not limited to the embodiments illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the claims are followed by reference numerals, such numerals are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting to the scope of the claims.

[0022] Throughout the specification unless otherwise specified, wt% means weight % of the total weight of soap composition of the present invention.

[0023] Various components of the composition are described in greater detail below.

[0024] Detailed description of the invention

[0025] These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, 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. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight / weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims 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.

[0026] Throughout the specification unless otherwise specified, wt% means weight % of the total weight of soap composition of the present invention.

[0027] Various components of the composition are described in greater detail below.

[0028] The present invention provides a soap bar composition comprising: 25 to 65 wt% total fatty matter, 0.01 to 3.5 wt% electrolyte, 0.01 to 2 wt% antimicrobial efficacy boosting agent, 3 to 45 wt% starch; and 10 to 30 wt% water; wherein the wherein the antimicrobial efficacy boosting agent is a different compound than the electrolyte.

[0029] Palm derivatives constitute major part of soap bar composition with inclusion to the levels of 60-80% of total fatty matter. It is advantageous for the soap industry to transition to sustainable sourcing of palm oil. Therefore, soaps with low Total Fatty Matter (TFM) are aimed to reduce the palm derivatives content in soap bar. Several routes have been taken to obtain a low TFM route including use of structurants. One of the routes was to use complex carbohydrate such as starch. With starch the inventors were able to make a soap bar with less than 60 TFM, without impacting the product sensory deliverables. However, the inventors were faced with a two fold objective of reducing the TFM of a soap bar and also have a soap bar with good antimicrobial benefits. It was observed that when the TFM of a soap bar was replaced with structurants such as starch, the antimicrobial efficacy was affected. In fact it was observed that a soap bar structured with starch lead to inferior antimicrobial efficacy vs even as ordinary soap bar. However, it was surprising finding by the inventors of the present invention that when particular compounds, identified as ‘antimicrobial efficacy boosting agents’ were added to the soap bar composition, the antimicrobial efficacy was improved from basal line with and without addition of antimicrobial actives.

[0030] Soap

[0031] The present invention relates to a soap composition. By a soap composition is meant a cleansing composition comprising soap which is in the form of a shaped solid. It is preferred that the composition is shaped in the form of noodles or bars. More preferably the composition of the invention is in the form of a bar. The bars in turn, could have a variety of shapes including rectangular, square, or oval cross section. The composition of the present invention is in the form of a shaped solid for example a bar. The cleaning soap composition is generally a wash off products have sufficient amounts of surfactants included therein that it is used for cleansing the desired topical surface e.g. the whole body, the hair and scalp or the face. It is applied on the topical surface and left thereon only for a few seconds or minutes and washed off thereafter with copious amounts of water.

[0032] The present invention provides a soap composition comprising: soap bar composition comprising: 25 to 65 wt% total fatty matter, 0.01 to 3.5 wt% electrolyte, 0.01 to 2 wt% antimicrobial efficacy boosting agent selected from Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof, 3 to 45 wt% starch; and 10 to 30 wt% water; wherein the wherein the antimicrobial efficacy boosting agent is a different compound than the electrolyte.

[0033] An expression called total fatty matter is used very widely in the field of soaps and detergents. The term abbreviated to “TFM”, is used to denote the wt% of fatty acid and triglyceride residues present in the soap composition without taking into account the accompanying cations. For a soap having 18 carbon atoms, an accompanying sodium cation will generally amount to about 8 wt%. Other cations may be employed as desired, for example zinc, potassium, magnesium, alkyl ammonium and aluminium.

[0034] The term soap means salts of fatty acids in which the accompanying cation may be an alkali metal, alkaline earth metal or ammonium ion, preferably an alkali metal. Preferably, the cation is sodium or potassium. The soap may be saturated or unsaturated and it depends on the nature of the corresponding fatty acid and / or oil used for saponification. The soap composition of the invention is especially useful for personal cleansing. The soap composition is preferably soap noodles or a soap bar. The soap composition of the present invention preferably comprises 20 to 65% of TFM, preferably 25 to 60% and more preferably 30 to 60 wt% TFM of the weight of the soap bar composition of the present invention. The term soap means salt of fatty acid. Preferably, the soap is soap of C8 to C24 fatty acids.

[0035] The cation may be an alkali metal, alkaline earth metal or ammonium ion, preferably alkali metals. Preferably, the cation is selected from sodium or potassium, more preferably sodium. The soap may be saturated or unsaturated. Saturated soaps are preferred over unsaturated soaps for stability. The oil or fatty acids may be of vegetable or animal origin.

[0036] The soap composition may be obtained by saponification of oils, fats or fatty acids. The fats or oils generally used to make soap bars may be selected from tallow, tallow stearins, palm oil, palm stearins, soya bean oil, fish oil, castor oil, rice bran oil, sunflower oil, coconut oil, babassu oil, and palm kernel oil. The fatty acids may be from coconut, rice bran, groundnut, tallow, palm, palm kernel, cotton seed or soyabean.

[0037] The fatty acid soaps may also be synthetically prepared (e.g. by the oxidation of petroleum or by the hydrogenation of carbon monoxide by the Fischer-Tropsch process). Resin acids, such as those present in tall oil, may also be used. Naphthenic acids may also be used.

[0038] The soap composition may additionally comprise synthetic surfactants selected from one or more from the class of anionic, non-ionic, cationic or zwitterionic surfactants, preferably from anionic surfactants. These synthetic surfactants, as per the present invention, are included in less than 15%, preferably less than 12%, more preferably less than 10% and sometimes absent from the composition.

[0039] The chain length of soaps depends on the fat or oil feedstock which is usually a blend. For purposes of this specification, "oil" and "fat" are used interchangeably, except where context demands otherwise. Longer chain fatty acid soaps (e.g., Ci6 palmitic or Cis stearic) are typically obtained from tallow and palm oils, and shorter chain soaps (e.g., C12 lauric) may typically be obtained from, for example, coconut oil or palm kernel oil. The fatty acid soaps produced may also be saturated or unsaturated (e.g., oleic acid). Typically, longer chain fatty acid soaps (e.g., C14 to C22 soaps) especially longer, saturated soaps are insoluble and do not generate enough foam upon use but they can make the foam creamier and more stable. Conversely shorter chain soaps (e.g., Cs to C12) and unsaturated soaps (e.g., oleic or linoleic acid soap) lather quickly. However, the longer chain soaps (typically saturated, although they may also contain some level of unsaturated such as oleic) are desirable to maintain structure and not dissolve as readily. Unsaturated soaps (e.g., oleic) are soluble and lather quickly, like short-chained soaps, but form a denser, creamier foam, like the longer chained soaps.

[0040] Iodine value is an indicator of unsaturation and there are well known methods of measurement of IV. One method is gas chromatography. In this method, methyl esters of the fatty acids are formed and analysed by the chromatographic technique. In addition, there are wet chemical methods of analyses. It is possible to measure iodine value of a fat blend before saponification. Additionally, it is possible to determine the iodine value of a soap (saponified oil or fatty acids) present in a finished good like a bar of soap or noodles of soap.

[0041] It is preferred that the soap composition has pH in the range from 9 to 13, when measured in a 4% solution with distilled water at 25°C.

[0042] Antimicrobial efficacy boosting agent

[0043] The present invention comprises 0.01 to 2 wt% of antimicrobial efficacy boosting agent, preferably 0.05 to 2 wt%, more preferably 0.07 to 1.8 wt% and most preferably 0.1 to 1.5 wt% by weight of the soap bar composition of the present invention.

[0044] The present invention comprises an antimicrobial efficacy boosting agent. It is preferred that the composition of the present invention 0.01 to 2 wt% antimicrobial efficacy boosting agent is selected from Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof; by weight of the soap bar composition of the present invention.

[0045] It is preferred that the composition of the present invention has either 0.01 to 2 wt% of an antimicrobial efficacy boosting agent selected from Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or 0.01 to 2 wt% of an antimicrobial efficacy boosting agent selected from Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof; by weight of the soap bar composition of the present invention.

[0046] In one embodiment of the present invention, the soap bar composition comprises 0.01 to 2 wt% of antimicrobial efficacy boosting agent, preferably 0.05 to 1.2 wt%, more preferably 0.07 to 1.8 wt% and most preferably 0.1 to 1.5 wt% by weight of the soap bar composition of the present invention, wherein the antimicrobial efficacy boosting agent is selected from Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof.

[0047] It is preferred that when the antimicrobial efficacy boosting agent selected from, Group I, it is selected from the group of sodium carbonate, sodium silicate, sodium aluminate, potassium carbonate, potassium silicate, potassium aluminate, , lithium carbonate, lithium silicate, lithium aluminate and mixtures thereof.

[0048] It is preferred that when the antimicrobial efficacy boosting agent is selected from the Group II, the group is sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide and lithium hydroxide and mixtures thereof.

[0049] It is preferred that the antimicrobial efficacy boosting agent is a different compound than the electrolyte.

[0050] Electrolyte

[0051] Inclusion of small amount of an electrolyte (other than soap) can influence the liquid and solid phase ratio. Increasing the electrolyte content lowers the solubility of soap thereby increasing the solid phase amount, on the other hand lowering the electrolyte levels make the bars softer.

[0052] Electrolytes as per this invention include compounds that substantially dissociate into ions in water. Electrolytes as per this invention are not an ionic surfactant. Suitable electrolytes for inclusion in the soap making process are alkali metal salts. Preferred alkali metal salts include sodium sulfate, sodium chloride, sodium acetate, sodium citrate, potassium chloride, potassium sulfate, sodium carbonate and other mono or di or tri salts of alkaline earth metals, more preferred electrolytes are sodium chloride, sodium sulfate, sodium citrate, potassium chloride and especially preferred electrolyte is sodium chloride sodium sulphate, sodium citrate or a combination thereof. For the avoidance of doubt, it is clarified that the electrolyte is a non-soap material. It is preferred that the electrolyte is included in the soap composition during the step of saponification to form the soap.

[0053] It is preferred that sodium sulphate, sodium carbonate, sodium chloride and or sodium citrate or combinations thereof are used as electrolytes for the composition of the present invention.

[0054] It is preferred that composition of the invention comprises 0.01 to 3.5 wt %, more preferably in the range of 0.5 to 3 wt % electrolyte, and most preferably 0.7 to 2.5% by weight of the composition. Preferred electrolytes include sodium sulfate, sodium chloride, sodium citrate, potassium chloride, potassium sulfate, and other mono or di or tri salts of alkaline earth metals, more preferred electrolytes are sodium chloride, sodium sulfate, potassium chloride and especially preferred electrolytes are sodium chloride and sodium sulfate and combinations thereof. For the avoidance of doubt is clarified that the electrolyte is a non-soap material.

[0055] It is preferred when sodium sulphate is present, it is present in the range of 0.01 to 3.5 wt %, more preferably in the range of 0.5 to 3 wt %, and most preferably 0.7 to 2.5% by weight of the composition. It is preferred that sodium sulphate is at least 0.1 wt%, more preferably at least 0.5wt%, and most preferably at least 0.7 wt% and it is preferred that it is not more than 3.5wt%, more preferably not more than 3 wt%, furthermore preferably not more than 2.8 wt% and most preferably not more than 2.5wt% of the total weight of composition of the present invention.

[0056] It is preferred that when sodium chloride is present, it is in the range of 0.01 to 3.5 wt %, more preferably in the range of 0.5 to 3 wt %, and most preferably 0.7 to 2.5% by weight of the composition. It is preferred that sodium chloride is at least 0.1 wt%, more preferably at least 0.5wt%, and most preferably at least 0.7 wt% and it is preferred that it is not more than 3.5wt%, more preferably not more than 3 wt%, furthermore preferably not more than 2.8 wt% and most preferably not more than 2.5wt% of the total weight of composition of the present invention. It is preferred that when sodium citrate is present, it is in the range of 0.01 to 3.5 wt %, more preferably in the range of 0.5 to 3 wt %, and most preferably 0.7 to 2.5% by weight of the composition. It is preferred that sodium citrate is at least 0.1 wt%, more preferably at least 0.5wt%, and most preferably at least 0.7 wt% and it is preferred that it is not more than 3.5wt%, more preferably not more than 3 wt%, furthermore preferably not more than 2.8 wt% and most preferably not more than 2.5wt% of the total weight of composition of the present invention.

[0057] In the composition of the present invention, the antimicrobial efficacy boosting agent is a different compound than the electrolyte.

[0058] Water- Moisture content

[0059] The soap compositions of the present invention have moisture or water content upto 30wt% of the weight of the soap bar. The soap compositions of the present invention have 10 to 30 wt% of water, preferably 12 to 28 wt%, and most preferably 15 to 25 wt% by weight of the soap composition.

[0060] Polyol

[0061] The soap bar composition of the present invention optionally comprise a polyol, preferably in the range of 0.01 to 12 wt%. Preferred levels range from 1 to 10% by weight of the soap composition, more preferred levels range from 1.5 to 9% and most preferred levels range from 2 to 8.5 wt% by the weight of the soap composition.

[0062] The extruded soap compositions of the present invention comprise polyols 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.

[0063] The composition 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. 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.

[0064] 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; and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG); and alkanolamine, for example trialkanolamine such as triethanolamine (TEA).

[0065] Especially preferred polyol are glycerine, propylene glycol, sorbitol and their mixtures. Another polyol which may be used is trialkanolamine such as triethanolamine (TEA), this is both a triol and an amine.

[0066] Antimicrobial active

[0067] The cleansing compositions of the present invention preferably include an antimicrobial active which preferably is an antibacterial active. It is preferred that the the composition comprises 0.00001 to 5 wt% of an antimicrobial active, more preferably 0.0001 to 3 wt% and most preferably 0.001 to 2.5 wt% of an antimicrobial active by weight of the soap composition of the present invention.

[0068] The active is primarily responsible for antibacterial action. Suitable antibacterial actives include Suitable antibacterial actives include 2-hydroxy-4,2',4'-trichlorodiphenylether (DP300); 2,6-dimethyl-4-hydroxychlorobenzene (PCMX); 3,4,4'-trichlorocarbanilide (TGC); 3- trifluoromethyl-4,4'-dichlorocarbaniide (TFC); 2,2'-dihydroxy-3,3',5,5',6,6'- hexachlorophenylmethane; 2,2'-dihydroxy-3,3', 5,5'-tetrachlorodiphenylmethane; 2,2'- dihydroxy-3,3',dibromo-5,5'-dichlorodiphenylmethane; oligodynamic metals, 2-hydroxy-4,4'- dichlorodiphenylether; 2-hydroxy-3,5',4-tribromodiphenlylether; and 1-hydroxyl-4-methyl-6- (2,4,4-trimethylpentyl)-2(1 H)-pyridinone (Octopirox), thymol and terpeniol. Particularly preferred antibacterial actives are thymol and terpeniol, optimally used in combination. In preferred compositions, the content of thymol ranges from 0.001 to 5 wt%, more preferably 0.01 to 1 wt% and most preferably 0.01 to 0.5 wt% by weight of the soap composition. Above the preferred range, the compositions may have strong smell, which may not be preferred by some consumers. However, suitable strong masking agents liked perfumes can be used to mask the strong odour of thymol or terpeniol. As an alternative to thymol; thyme oil or thyme extract may also be added. Thyme oil or thyme extract is obtained from the thyme plant. Thyme plant refers to a plant belonging be genus Thymus and includes but is not limited to Thymus vulgaris, Thymus zygis, Thymus satureoides, Thymus mastichina, Thymus broussonetti, Thymus maroccanus, Thymus pallidus, Thymus algeriensis, Thymus serpyllum, Thymus pulegoide, and Thymus citriodorus .

[0069] It is preferred that when the composition of present invention comprises an antimicrobial active, it is preferably an antibacterial active and preferably selected from the group of wherein the antimicrobial active is selected from the group of silver salts and silver compounds, thymol, terpineol and their analogues, ZPTO, chloroxylenol, PCMX, triclosan and trichlorocarbanilide and mixtures thereof.

[0070] The cleansing composition of the present invention may comprise a metal having oligodynamic activity as an antimicrobial active. It (also called as oligodynamic action) is the effect of inhibiting, or killing micro-organisms by the use of very small amounts of a chemical substance. Several metals exhibit such an effect. Preferred metals are silver, copper, zinc or gold. Silver is particularly preferred. In the ionic form it may exist as a salt or any compound in any applicable oxidation state.

[0071] When the cleansing composition of the present invention comprises oligodynamic metal, it comprises 0.00001 to 0.01 wt% of oligodynamic metal. It is preferred that the metal is present in the form of a compound, more preferably a compound of silver; then an appropriate amount of the compound is included so that the active metal content is within the broad and preferred ranges as already indicated. When present, the compound is present in the composition at a level equivalent to metal content of 0.00001 to 0.01 wt% at the broadest level as disclosed earlier, more preferably from 0.0001 wt% to 0.005 wt% and most preferably from 0.0003 to 0.0015 wt%.

[0072] Silver (I) Compound The cleansing composition of the present invention may contain silver as the oligodynamic metal. It is further preferred that Silver is included in the form of Silver(l) compound but may also be in the form of particles, eg., nanoparticles.

[0073] Silver(l) compounds are one or more water-soluble silver(l) compounds having silver ion solubility at least 1.0 x1 O'4mol / L (in water at 25°C). Silver ion solubility, as referred to herein, is a value derived from a solubility product (Ksp) in water at 25°C, a well known parameter that is reported in numerous sources. More particularly, silver ion solubility [Ag+], a value given in mol / L may be calculated using the formula:

[0074] [Ag+] = (Ksp •X)<1 / <x+1» , wherein Ksp is the solubility product of the compound of interest in water at 25°C, and x represents the number of moles of silver ion per mole of compound. It has been found that Silver(l) compounds having a silver ion solubility of at least 1 x 10'4mol / L in are suitable for use herein. Silver ion solubility values for a variety of silver compounds are given in Table 1 :

[0075] TABLE 1 When silver is present it is present in the form of a compound selected from silver oxide, silver nitrate, silver acetate, silver sulfate, silver benzoate, silver salicylate, silver carbonate, silver citrate or silver phosphate. In particularly preferred compositions the silver(l) compound is silver oxide. It is preferred that the Silver compound is present in the composition at a level equivalent to metal content of 0.00001 to 0.01 wt% at the broadest level as disclosed earlier, more preferably from 0.0001 wt% to 0.005 wt% and most preferably from 0.0003 to 0.0015 wt%.

[0076] Skin hygiene is of high priority to present day consumers. Consumers all over the world use various kinds of skin hygiene compositions.

[0077] Skin generally contains several different micro-organisms in concentrations exceeding millions or even billions of colony forming units (cfu) per square centimetre (cm2). Many of these micro organisms are harmless, but there are also various pathogenic types or subspecies present, such as Escherichia coli, also referred to a E. coli, and Staphylococcus aureus, also referred to as S. aureus. Several other bacteria can be found in the skin flora, such as Staphylococcus epidermidis, also referred to as S. epidermidis, which is generally non-pathogenic, but is thought to be causing unpleasant body odour. Therefore present day consumers prefer cleansing products, especially skin cleansing products that can provide antimicrobial action.

[0078] The efficacy of anti-bacterial activity of skin cleansing products containing antimicrobial actives, however, can be measured in a variety of ways.

[0079] The efficacy of anti-bacterial activity of skin cleansing products containing antimicrobial actives is generally measured in two types of assays. The first type measures the effect of anti-bacterial actives deposited on skin and is thus reflective of substantive effects. The second type measures the ability of the formulation to cause quick kill (less than 1 minute) of bacteria as determine by in-vitro solution tests.

[0080] The time of contact of bacteria with the cleanser in the invitro, short time kill assay is somewhat reflective of cursory wash conditions. In fact, a cursory wash may take much less than one minute.

[0081] Since many or most people who wash with cleansing bars may not use the bar for longer duration and may in reality be less than few minutes (the average wash time for children may be even shorter), it becomes apparent that there is a need to deliver anti-bacterial activity in a short period of time (e. g., 60 seconds or less, preferably 30 seconds or less) and, therefore, ways for reassuring quick-kill effect on bacteria are quite critical. Therefore, people prefer compositions that give more efficacious antimicrobial action in a short period.

[0082] Preferred antimicrobial compositions include 0.001 to 5 wt%, more preferably 0.01 to 1 wt% and most preferably 0.01 to 0.5 wt% thymol by weight of the soap composition of the present invention. Most of the useful fast acting antimicrobial compositions have thymol higher than 0.01 wt%, but lesser than 1 wt%.

[0083] Preferred antimicrobial compositions include 0.001 to 5 wt%, more preferably 0.01 to 1 wt% and most preferably 0.01 to 0.5 wt% terpineol. Most of the useful fast acting antimicrobial compositions have terpineol higher than 0.01 wt%, but lesser than 1 wt%. Below the preferred range, the kinetics of microbial kill was lower. Above the preferred range, the compositions were found to have strong smell, which may not be preferable to some consumers. Terpineol is preferably selected from alpha-terpineol, beta-terpineol, gammaterpineol or mixtures thereof, alpha-terpineol being particularly preferred. Terpineol may be added to the antimicrobial compositions in purified form.

[0084] As an alternative to terpeniol, pine oil, which includes terpineol, may also be added to the mild personal cleansing compositions.

[0085] Rheology modifying agent

[0086] The composition of the present invention preferably comprise a rheology modifying agent, which means an agent that affects the rheology of the soap bar compositions. These agents may be thickening agents such as polymers. The composition of the present invention may comprise rheology modifying agent in the range of 0.001 to 10 wt%, more preferably 0.01 to 9 wt% further preferably in the range of 0.01 to 8.5 wt% and most preferably comprises 0.01 to 5 wt.% by weight of the soap bar composition of the present invention.

[0087] Thickening agents may be 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 cleanser compositions, to enhance in-use and after-use skin sensory feels, and to enhance lather creaminess and lather stability. Amount of the polymers, when present, may range from 0.01 to 10% by weight of the composition. It is preferred that the thickening polymers are present in the range of 0.001 to 10 wt%, more preferably 0.01 to 9 wt% further preferably in the range of 0.01 to 8.5 wt% and most preferably comprises 0.01 to 5 wt.% by weight of the soap bar composition of the present invention.

[0088] Examples of water soluble / or dispersible polymers and rheology modifiers include the carbohydrate gums such as cellulose gum, microcrystalline cellulose, cellulose gel, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, methyl cellulose, ethyl cellulose, guar gum, gum karaya, gum tragacanth, gum arabic, gum acacia, gum agar, xanthan gum and mixtures thereof; alkali swellable acrylic polymers such as crosslinked acrylate copolymers, polyacrylate crosspolymers; polyacrylate crosspolymers (Sepimax zen), lightly cross-linked acrylate copolymer (Carbopol Aqa SF01), hydroxypropyl methylcellulose (and) cellulose gum (and) xanthan gum (TEXTURE PURE SA ), Amaze XT(De hydroxanthan gum); emulsion polymers such as Aculyn® 28, cationic polymer such as modified polysaccharides including cationic guar such as Jaguar® C13S, Jaguar® C17, or Jaguar® C16; cationic modified cellulose such as UCARE® Polymer JR 30 or JR 40; 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 galactomannans such as Galactasol® 800 series by Henkel, Inc.; Quadrosoft® LM-200; and Polyquaternium-24®. 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). Other cationic cellulose derivatives are cationic cationic guar gum derivatives.

[0089] Complex Carbohydrate

[0090] The soap composition of the present invention comprises an complex carbohydrate comprising starch. There are two types of carbohydrates: simple and complex. Simple carbohydrates are made of one or two sugar molecules. Complex carbohydrates include starch and fiber. It is preferred that the complex carbohydrate is a polysaccharide and most preferably comprises starch. Polysaccharides, meanwhile, have a general formula of Cx(H2O)y where x and y are usually large numbers between 200 and 2500. When the repeating units in the polymer backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to (CeHioOsJn, where typically 40 < n < 3000.

[0091] It is preferred that the complex carbohydrate is starch in the soap composition ranges from 3 to 45 wt%, more preferably from 3.5 to 40 wt% and most preferably from 3.7 to 35wt% by weight of the soap composition.

[0092] Starch (a polymer of glucose) is a preferably polysaccharide used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called "animal starch".

[0093] In another aspect of the present invention the complex carbohydrate is starch or modified starch. Suitable starch materials include natural starch (from corn, wheat, rice, potato, tapioca and the like), pre-gelatinized starch, various physically and chemically modified starch and mixtures thereof. By the term natural starch is meant starch which has not been subject to chemical or physical modification - also known as raw or native starch. Starch may be natural or native starch from maize (corn), cassava, wheat, potato, rice and other natural sources of it. Raw starch with different ratio of amylose and amylopectin: e.g. maize (25% amylose); waxy maize (0%); high amylose maize (70%); potato (23%); rice (16%); sago (27%); cassava (18%); wheat (30%) pea (35% amylose) and others. The raw starch can be used directly or modified during the process of making the liquid personal cleansing composition such that the starch becomes gelatinized. Another suitable starch is pregelatinized, which is starch that has been gelatinized before it is added as an ingredient in the present liquid personal cleansing compositions. Various forms are available that will gel at different temperatures, e.g., cold water dispersible starch.

[0094] Organic and Inorganic Adjuvant Materials

[0095] The total level of the adjuvant materials used in the bar composition should be in an amount not higher than 50%, preferably 1 to 50%, more preferably 3 to 45% by wt. of the soap bar composition. The adjuvant system may optionally include insoluble particles comprising one or a combination of materials. By insoluble particles is meant materials that are present in solid particulate form and suitable for personal washing. Preferably, there are mineral (e.g., inorganic) or organic particles.

[0096] The insoluble particles should not be perceived as scratchy or granular and thus should have a particle size less than 300 microns, more preferably less than 100 microns and most preferably less than 50 microns.

[0097] Preferred inorganic particulate material includes talc and calcium carbonate. 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.

[0098] Calcium carbonate or chalk exists in three crystal forms: calcite, aragonite and vaterite. The natural morphology of calcite is rhombohedral or cuboidal, acicular or dendritic for aragonite and spheroidal for vaterite.

[0099] Examples of other optional insoluble inorganic particulate materials include aluminates, phosphates, insoluble sulfates, borates and clays (e.g., kaolin, china clay) and their combinations.

[0100] Organic particulate materials include: insoluble polysaccharides such as cellulose; synthetic polymers such as various polymer lattices and suspension polymers; insoluble soaps and mixtures thereof.

[0101] Bar compositions preferably comprise 0.1 to 25% by wt. of bar composition, preferably 5 to 15 by wt. of these mineral or organic particles.

[0102] An opacifier may be optionally present in the personal care composition. When opacifiers are present, the cleansing bar is generally opaque. Examples of opacifiers include titanium dioxide, zinc oxide and the like. A particularly preferred opacifier that can be employed when an opaque soap composition is desired is ethylene glycol mono- or di-stearate, for example in the form of a 20% solution in sodium lauryl ether sulphate. An alternative opacifying agent is zinc stearate.

[0103] The product can take the form of a translucent or transparent soap, in which case it will not contain an opacifier.

[0104] It is preferred that the soap composition of the present invention has a pH in the range from 9 to 13, when measured in a 4% solution with distilled water at 25°C.

[0105] A preferred bar may additionally include up to 30 wt% benefit agents. Preferred benefit agents include moisturizers, emollients, sunscreens, skin lightening agents and anti-ageing compounds. The agents may be added at an appropriate step during the process of making the bars. Some benefit agents may be introduced as macro domains.

[0106] Other optional ingredients like anti-oxidants, perfumes, polymers, chelating agents, colourants, deodorants, dyes, emollients, moisturizers, enzymes, foam boosters, germicides, additional anti-microbials, lathering agents, pearlescers, skin conditioners, stabilisers, superfatting agents, sunscreens may be added in suitable amounts in the process of the invention. Preferably, the 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.

[0107] The composition of the invention could be used to deliver antimicrobial benefits. Antimicrobial actives that are preferably included to deliver this benefits include oligodynamic metals or compounds thereof. Preferred metals are silver, copper, zinc, gold or aluminium. Silver is particularly preferred. In the ionic form it may exist as a salt or any compound in any applicable oxidation state. Preferred silver compounds are silver oxide, silver nitrate, silver acetate, silver sulfate, silver benzoate, silver salicylate, silver carbonate, silver citrate and silver phosphate, with silver oxide, silver sulfate and silver citrate being of particular interest in one or more embodiments. In at least one preferred embodiment the silver compound is silver oxide. Oligodynamic metal or a compound thereof is preferably included in 0.0001 to 2%, preferably 0.001 to 1% by weight of the composition. Alternately an essential oil antimicrobial active may be included in the composition of the invention. Preferred essential oil actives which may be included are terpineol, thymol, carvacol, (E) -2(prop-1-enyl) phenol, 2- propylphenol, 4- pentylphenol, 4-sec-butylphenol, 2-benzyl phenol, eugenol or combinations thereof. Furthermore preferred essential oil actives are terpineol, thymol, carvacrol or thymol, most preferred being terpineol or thymol and ideally a combination of the two. Essential oil actives are preferably included in 0.001 to 1%, preferably 0.01 to 0.5% by weight of the composition.

[0108] The soap composition may be made into a bar by a process that first involves saponification of the fat charge with alkali followed by extruding the mixture in a conventional plodder. The plodded mass may then be optionally cut to a desired size and stamped with a desirable indicia. An especially important benefit of the present invention is that, notwithstanding the high amount of water content of the soap bar, compositions thus prepared by extrusion are found to be easy to stamp with a desirable indicia.

[0109] The present invention also relates to a process to prepare the soap bar of the invention comprising the step of including substantially all of the structuring system to the soap when it is being produced during the saponification step. Preferably, at least, the polymer is included during the saponification stage.

[0110] Form and format

[0111] The soap composition of the invention could be in the form of noodles, sheets, flakes, chips or powder, more preferably noodles.

[0112] The term "noodles" is used to refer to generally cylindrical particles prepared by extrusion and cutting or breaking noodles generally containing soap as a major ingredient.

[0113] Noodles based on soap are commonly produced by mixing dried soap chips with colourants and other minor ingredients, homogenising by working in either a mill or a refiner, and then extruding through a perforated plate with fine holes. They are generally extruded continuously and then allowed to weather sufficiently to break up into pieces from 3 to 15 mm in length. A series of rotating knives can be fitted to the face of the plate to cut the extruded noodles automatically into suitable lengths, but these tend to cause a certain amount of bunching to take place. The degree of bunching depends on the geometry of the cutting knives and holes and is also greatly affected by the plasticity and stickiness of the noodles themselves. Even where a rotating knife is not used, the quality of the noodles is dependent on the physical properties of the extruded soap. Ideally, the soap should be sufficiently plastic to extrude satisfactorily through the holes in the perforated plate but not so soft and sticky that they bunch together after extrusion. They should also be sufficiently hard and brittle to break up into the desired length range.

[0114] While noodles of soap can be used for washing and cleaning purposes, practically such noodles are used as input or raw material for making bars or tablets of soap which are sold in shops and supermarkets and are used by consumers as a personal wash composition.

[0115] Therefore, in accordance with another aspect of the invention, disclosed is a bar of soap comprising a soap composition of the first aspect of the invention. The bar may be of any shape and size, but preferably is rectangular with rounded edges and of a size that allows it to be held comfortably in one hand.

[0116] Other ingredients

[0117] In addition to the saponified fatty matter and the polymeric gel, the soap composition of the invention, example noodles, and in particular the bars of soap, preferably comprises one or more of the following other ingredients. Choice of the ingredients and the amounts thereof are largely dependent on the formulation scientists and the purpose for which such noodles or bars are made.

[0118] Non-Soap Surfactant

[0119] The composition of the invention preferably includes a non-soap surfactant, which acts as a co-surfactant and which is selected from anionic, non-ionic, zwitterionic, amphoteric or cationic surfactant or a combination thereof. Preferably the composition comprises 0.1 to 15 wt % non-soap surfactant. More preferably the composition comprises 2 to 10 wt % non-soap surfactant and most preferably 3 to 6 wt % by weight of the soap composition.

[0120] Suitable anionic surfactants include water soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphuric acid ester radicals, and mixtures thereof. Examples of suitable anionic surfactants are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof.

[0121] The preferred water-soluble synthetic anionic surfactants are the alkali metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates and mixtures with olefin sulphonates and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates.

[0122] Suitable nonionic surfactants can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

[0123] Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensate containing from 40 to 80 percent of polyoxyethylene radicals by weight and having a molecular weight of from 5,000 to 11,000; tertiary amine oxides of structure R3NO, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxyethyl groups, for instance dimethyldodecylamine oxide; tertiary phosphine oxides of structure R3PO, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, for instance dimethyldodecylphosphine oxide; and dialkyl sulphoxides of structure R2SO where the group R is an alkyl group of from 10 to 18 carbon atoms and the other is methyl or ethyl, for instance methyltetradecyl sulphoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans.

[0124] Suitable cationic surfactants that can be incorporated are alkyl substituted quarternary ammonium halide salts e.g. bis (hydrogenated tallow) dimethylammonium chlorides, cetyltrimethyl ammonium bromide, benzalkonium chlorides and dodecylmethylpolyoxyethylene ammonium chloride and amine and imidazoline salts for e.g. primary, secondary and tertiary amine hydrochlorides and imidazoline hydrochlorides.

[0125] Suitable amphoteric surfactants are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance sodium 3-dodecylamino-propionate, sodium 3- dodecylaminopropane sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate.

[0126] Suitable zwitterionic surfactants are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance 3-(N-N-dimethyl-N-hexadecylammonium) propane-1 -sulphonate betaine, 3-(dodecyl methyl sulphonium) propane-1 -sulphonate betaine and 3-(cetylmethylphosphonium) ethane sulphonate betaine.

[0127] Further examples of suitable detergent-active compounds are compounds commonly used as surface-active agents given in the well-known textbooks “Surface Active Agents”, Volume I by Schwartz and Perry and “Surface Active Agents and Detergents”, Volume II by Schwartz, Perry and Berch.

[0128] Opacifier

[0129] An opacifier may be optionally present in the composition. When opacifiers are present, the cleansing bar is generally opaque, i.e. “opacification”. Examples of opacifiers include titanium dioxide, zinc oxide and the like. A particularly preferred opacifier that can be employed when an opaque rather than a transparent soap composition is desired is ethylene glycol mono- or di-stearate, for example in the form of a 20% solution in sodium lauryl ether sulphate. An alternative opacifying agent is zinc stearate.

[0130] Benefit agents

[0131] Preferably the soap composition of the invention comprises one or more benefit agent not already disclosed earlier. Preferably the benefit agent is an emollient, sunscreen, anti-ageing compounds or moisturizers and humectants. The agents may be added at an appropriate step during the process. Some benefit agents may be introduced as macro domains.

[0132] Examples of moisturizers and humectants include cetyl alcohol, ethoxylated castor oil, paraffin oils, lanolin and its derivatives. Silicone compounds such as silicone surfactants like DC® 3225C (Dow Corning) and / or silicone emollients, silicone oil (DC-200® ex. Dow Corning) may also be included. Further examples include glycerin, oat kernel flour, Petrolatum, Aquaporin and hydroxyethyl urea.

[0133] Sunscreens such as 4-tertiary butyl-4'-methoxy dibenzoylmethane (available under the trade name PARSOL®1789 from Givaudan) or 2-ethyl hexyl methoxy cinnamate (available under the trade name PARSOL® MCX from Givaudan) or other IIV-A and IIV-B sun-screens may also be added. Further examples include Helioplex® (Diethylhexyl naphthylate), Ensulizole®, Ethylhexyl salicylate, Tinosorb® (S & M), Octocrylene® and Mexoryl®.

[0134] Lipids such as cholesterol, ceramides, and pseudoceramides, and exfoliant particles such as polyethylene beads, walnut shells, apricot seeds, flower petals and seeds may also be present.

[0135] The composition can also optionally include other ingredients conventionally used in soap such as lather boosters, colourants and opacifiers and skin tone agents such as hexyl resorcinol, Soybean extract (Bowman Birk inhibitor), Octadecenedioic acid, (Ariatone® DC), niacinamide, Seppiwhite®, Acetylglucosamine, Pitera Extract, Symwhite® and Melano- block® (Calcium pantothenate). Further, the composition of the invention may comprise antiaging ingredient such as retinol, hyaluronic acid, Collagen, CoQ10 (ubiquinone), retinyl propionate, peptides, retinyl palmitate, Jasmonic acid derivatives and Proxylane®.

[0136] Other adjunct materials may include germicides and preservatives. These ingredients normally will be in amounts less than 2 wt %, usually less than 0.5 wt % and may include silver salts and silver compounds, thymol, terpineol and their analogues, ZPTO, chloroxylenol, PCMX, triclosan and trichlorocarbanilide.

[0137] The soap composition may include structurants. These may include water insoluble particulate material. Structurants may, individually or combined, support 0 to 25 wt%. Preferred inorganic particulate material includes talc and calcium carbonate. Talc is a magnesium silicate mineral material, with a sheet silicate structure represented by the chemical formula Mg3Si4(O) (OH)2 and may be available in the hydrated form. Talc has a plate-like morphology and is substantially oleophilic / hydrophobic.

[0138] Examples of other optional insoluble inorganic particulate materials include zeolites aluminates, silicates, phosphates, insoluble sulfates, clays (e.g., kaolin, china clay), titanium oxide, zinc oxide and their combinations.

[0139] The compositions of the invention may additionally comprise anti-cracking agents such as acrylate polymers.

[0140] The term “slip modifier” is used herein to designate materials that when present at relatively low levels (generally less than 1.5% based on the total weight of the bar composition) will significantly reduce the perceived friction between the wet bar and the skin. The most suitable slip modifiers are useful, individually or combined, at a level of 1% or less, preferably from 0.05 to 1% and more preferably from 0.05 to 0.5%.

[0141] The composition of the present invention optionally comprises modified poly ethylene glycol in the range of 0.01 to 0.08% as a slip modifier and / or for other sensory benefits. The composition of the present invention may also optionally comprise modified ethylene acrylate copolymer in the range of 0.1 to 0.05% as a benefit agent. Suitable slip modifier include petrolatum, waxes, lanolins, poly-alkane, poly-alkene, polyalkyene oxides, high molecular weight polyethylene oxide resins, silicones, polyethylene glycols and mixtures thereof.

[0142] Free fatty acids (FFA) up to 3% such as coconut fatty acid, PKO fatty acid, lauric acid are commonly used in soap bars for overall quality and process improvement. Free fatty acid higher than 3% could lead to soft and sticky mass and could negatively impact one or more physical feature. In at least one form, level of FFA in compositions of the invention is 0.05 to 3%, preferably 0.1 to 2%, more preferably 0.1 to 1.5 wt%.

[0143] A variety of test method have been used to determine properties of the soap compositions.

[0144] The test methods are hardness testing protocol, using a 30° conical probe which penetrates to depth of 15 mm. Another test is the rate of wear (RoW) which relates to the amount of material which is lost by a soap bar product under controlled conditions. These conditions for use, mimic approximately the way consumers use the product. A further test is done to check for the extent of as the physical damage which may result (or not) from the sequence of washdown and drying of the bar. Yet another test is to determine “mush” defined as the jelly, creamy material that forms when toilet soap bars absorb water. The Mush Immersion Test gives a numerical value of the amount of mush formed on a bar.

[0145] All the aforesaid test methods have been described in US20190016994 A1 (Unilever).

[0146] Process of the invention

[0147] In accordance with a second aspect is disclosed a process for preparing a soap composition of the first aspect, comprising, i) saponifying a fatty matter with an alkali to produce a saponified mass; ii) adding 3 to 45 wt% starch by weight of the resulting soap bar composition and water to obtain a soap mass to result in a soap composition; and iii) optionally extruding the soap mass resulting from step (ii) to obtain the soap bar according to the first aspect; wherein the antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof, is added at step (i) or (ii); and wherein the electrolyte is added at step (i) or (ii).

[0148] It is preferred that in the process of the present invention, the electrolyte is selected from the group of sodium citrate, sodium sulphate, sodium chloride and mixtures thereof.

[0149] It is preferred that in the process of the present invention, the soap composition comprises 25 to 65 wt% total fatty matter and 10 to 30 wt% moisture.

[0150] It is preferred that in the process of the present invention, the starch is native starch, ungelatinized, pre-gelatinized starch, converted starch or a mixture thereof in the range of 3 to 45 wt% by weight of the soap bar composition.

[0151] It is preferred that the process comprises a step of addition of an antimicrobial active at step (i) or (ii). It is preferred that the antimicrobial active is selected from the group consisting of silver salts and silver compounds, thymol, terpineol and their analogues, ZPTO, chloroxylenol, PCMX, triclosan and trichlorocarbanilide and mixtures thereof.

[0152] The soap bar composition according to the present invention may be produced on a commercial scale by any of the processes known to a person skilled in in the art. The soap could be a cast melt soap bar or an extruded soap bar. Preferably the soap bar composition of the present invention is prepared using the extrusion route.

[0153] The specific process that may be employed using the above described general process for soap composition manufacture.

[0154] The present invention provides use of starch and an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium, in a soap bar according to the first aspect for providing enhanced antimicrobial efficacy as compared to a soap bar without an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium. The invention will now be illustrated by means of the following non-limiting examples.

[0155] EXAMPLES

[0156] The soap compositions for the examples were prepared in accordance with the present invention.

[0157] The soap manufacturing process starts primarily with the basic step of saponification of the fat charge with an alkali to produce a soap mass. The process may or may not include other excipients and additives such as but not limited to electrolytes, chelating agents, polyols etc. A required quantity of fatty acids & other raw materials were weighed & charged into the mixer. An aqueous solution of alkali was used for this neutralization reaction. The completion of the neutralization was checked through phenolphthalein indicator test and if required additional alkali to be added to ensure completion of the neutralization reaction. In-process quality check to be done before the soap mass is passed through further processes including but not limited to passing of soap mass through chilled rolls and then to refiner to convert into noodle form.

[0158] In the final step, the soap noodles are added to the mixer. They are crushed. Requisite amount of other formula additives including but not limited to starch, antimicrobial efficacy boosting agents, antimicrobial actives etc are added and mixing continued. Required colourants are dissolved in water prior to addition to the mixer contents. Fragrance is added at the end and the mixing is continued to get uniform macro mixing. The resultant formula mass is then dropped & conveyed for further mechanical processes including but not limited to its extrusion from a plodder post which it is stamper into soap bars of desired shape, size and branding.

[0159] The compositions E1 to E4 were prepared for comparative analysis and are out of the scope of the present invention. E1 is a control beauty soap bar currently found in the market, without starch, it does not have antimicrobial agent or any antimicrobial efficacy boosting agent. E2 is a similar soap composition but providing antimicrobial benefits through addition of antimicrobial actives such as thymol, terpineol and silver oxide. E2 is also without starch and does not have any antimicrobial efficacy boosting agent. E3 and E4 are soap compositions with starch and also having antimicrobial actives. E3 and E4 however do not have any antimicrobial efficacy boosting agents.

[0160] The compositions E5 to E7 are prepared according to the present invention and are compositions within the scope of the present invention. E5 is a soap composition with starch and antimicrobial efficacy boosting agent such as sodium carbonate, E5 however does not have any antimicrobial actives to test the effectiveness of antimicrobial efficacy boosting agents in absence of antimicrobial actives. E6 and E7 are compositions with starch and antimicrobial efficacy boosting agent such as sodium carbonate, and antimicrobial actives to check the effectiveness of antimicrobial efficacy boosting agents in presence of antimicrobial actives.

[0161] Antimicrobial Efficacy Test

[0162] Test for Evaluation of Bacterial Reduction Efficacy in soap bar compositions of the present invention was based on the in vitro Test Method: ASTM E2783-22, Standard Test Method for Assessment of Antimicrobial Activity for Water Miscible Compounds using Time - Kill procedure.

[0163] An appropriate aliquot of the challenge suspension (test organism) was transferred to a vial containing an adequate amount of 8% test solution. The challenge suspension was exposed to the test solution for the contact time. Upon elapse of the exposure time, an appropriate aliquot was transferred from the above vial to a test tube containing suitable neutralizing broth. Additional 10-fold dilutions were prepared in neutralizing broth. Aliquots were enumerated using standard microbiological plate count techniques. The plates were incubated at 35o C ± 2°C for 24-48 hours. Similarly, Control was tested, with dilution fluid, instead of test solution under identical test conditions.

[0164] The Log Reduction for the challenge suspension attributable to the test solution at the timed exposure was calculated for each replicate as follows:

[0165] Log10 reduction (LR) = Log 10 of control - Log 10 of test material The Average Log10 Reduction for the challenge suspension attributable to the test solution was calculated for the time exposure as follows:

[0166] Average Log10 Reduction = Logl0Reductions

[0167] Where: 3 = Number of replicates Higher the log reduction, better is the product of antimicrobial efficacy I bacterial reduction efficacy

[0168] The examples of Table 1 were tested for antimicrobial efficacy for E.coli ATCC 10536, E.coli ATCC BAA 196 and K.pneumoniae ATCC BAA 2146. The results of the efficacy study are given in terms of Average Log10 Reduction.

[0169] Table 1

[0170] It is clearly evident from the examples as presented in Table 1 and their observations of the antimicrobial efficacy studies that the examples E5 to E7 are far more superior as compared to the examples E1 to E4.

[0171] E1, which is a control beauty soap bar currently found in the market, without any starch, and does not have antimicrobial agent or any antimicrobial efficacy boosting agent, when tested for antimicrobial efficacy against E.coli ATCC 10536, the composition E1 was observed to have some antimicrobial efficacy. E2 was similar to E1 but with addition of antimicrobial actives and as expected E2 showed better antimicrobial efficacy than E1. E3 and E4 were compositions with antimicrobial actives and starch, however it was unexpected observation of the inventors to find that addition of starch had reduced the antimicrobial efficacy of the soap composition even though the antimicrobial actives at similar concentration of E2 composition.

[0172] When composition E5 comprising of starch was prepared in absence of antimicrobial actives but in presence of antimicrobial efficacy boosting agent such as sodium carbonate, it was observed that the antimicrobial efficacy of E5 of the present invention was comparable in terms of E.coli ATCC 10536, taking into account the acceptable standard deviation of error. Similarly when E5 was compared to soap compositions that were structured with starch having no antimicrobial agent and without any antimicrobial efficacy boosting agent, E5 performed much superior to these compositions showing the role of antimicrobial efficacy boosting agents in conditions when the antimicrobial efficacy is suppressed in presence of starch.

[0173] When antimicrobial actives were added to the composition of E5, compositions E6 and E7 were achieved, it was seen that the antimicrobial efficacy of E6 and E7 were compared with similar compositions E3 and E4 (without antimicrobial efficacy boosting agents), the effect of presence of antimicrobial efficacy boosting agents was clearly seen to be superior.

Claims

Claims1. A soap bar composition comprising: a. 25 to 65 wt% total fatty matter, b. 0.01 to 3.5 wt% electrolyte, wherein electrolyte is not an ionic surfactant; c. 0.01 to 2 wt% antimicrobial efficacy boosting agent selected from: i. Group I- alkali carbonate, silicate, aluminate, salts and mixtures thereof, or ii. Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof, d. 3 to 45 wt% starch; and e. 10 to 30 wt% water; wherein the antimicrobial efficacy boosting agent under (c) is a different compound than the electrolyte under (b); wherein the composition comprises 0.00001 to 5 wt% of an antimicrobial active by weight of the soap bar composition.

2. A soap composition according to claim 1 , wherein the starch is native, modified, pregelatinized, native ungelatinized, partially ungelatinized or partially hydrolyzed.

3. A soap composition according to claim 1 or 2, wherein the antimicrobial active is selected from the group of silver salts and silver compounds, thymol, terpineol and their analogues, Zinc pyrithione (ZPTO), chloroxylenol, para- chloro-meta-xylenol (PCMX), triclosan and trichlorocarbanilide and mixtures thereof.

4. A composition according to anyone of preceding claims 1 to 3, wherein the composition comprises non-soap surfactant in an amount of up to 15% by weight of the soap bar composition.

5. A composition according to any one of the preceding claims 1 to 4, wherein the composition comprises 0.01 to 5 wt.% of a rheology modifying agent comprising a polymer by weight of the soap bar composition.

6. A soap composition according to any one of the preceding claims 1 to 5, wherein the composition has a pH in the range from 9 to 13, when measured in a 4% solution with distilled water at 25°C.

7. A soap composition according to any one of the preceding claims 1 to 6, wherein the composition comprises 0.01 to 12 wt% of polyol by weight of the soap bar composition.

8. A process for preparing a soap bar composition according to anyone of the preceding claims 1 to 7, the process comprising the steps of: i) saponifying a fatty matter with an alkali to produce a saponified mass; ii) adding 3 to 45 wt% starch by weight of the resulting soap bar composition and water to obtain a soap mass to result in a soap composition; and iii) optionally extruding the soap mass resulting from step (ii) to obtain the soap bar according to anyone of the preceding claims from 1 to 7. wherein the antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium and mixtures thereof, is added at step (i) or (ii); and wherein the electrolyte is added at step (i) or (ii).

9. A process according to claim 8, wherein the process comprises a step of adding of an antimicrobial active at step (i) or (ii).

10. A process according to claim 9, wherein the antimicrobial active is selected from the group consisting of silver salts and silver compounds, thymol, terpineol and their analogues, Zinc pyrithione (ZPTO), chloroxylenol, para-chloro-meta- xylenol (PCMX), triclosan and trichlorocarbanilide and mixtures thereof.

11. Use of starch and an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate, silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium, in a soap bar according to anyone of the preceding claims 1 to 7, for providing enhanced antimicrobial efficacy as compared to a soap bar without an antimicrobial efficacy boosting agent selected from: Group I- alkali carbonate,silicate, aluminate salts and mixtures thereof, or Group II- hydroxides of sodium, potassium, magnesium and calcium and lithium.

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