Soap bars comprising potassium soap

Abstract

The present invention relates to an soap bar composition comprising, 30 to 75 wt% of total fatty matter (TFM) wherein 2 to 40 wt% of the composition comprises soluble fatty matter; 1 to 10 wt% non-soap surfactant; 12 to 35 wt% water; and 2 to 5 wt% electrolyte, wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L; wherein 0.5 to 20 wt% of the soap bar composition comprises potassium soap.

Description

[0001] SOAP BARS COMPRISING POTASSIUM SOAP

[0002] Field of the invention

[0003] The invention relates to bars which are predominantly fatty acid soap bar compositions comprising potassium soap.

[0004] Background of the invention

[0005] Soap bars for cleansing are typically prepared by direct saponification of fats and oils or by neutralization of free fatty acids. In the saponification process, various oils and fats (e.g., palm oil, tallow, palm kernel oil, coconut oil etc.) are blended and saponified in the presence of alkali (usually NaOH) to yield alkaline salts of fatty acids and glycerol. Glycerol is then typically extracted with brine to yield dilute fatty acid soap solution containing soap and aqueous phase (e.g., 70% soap and 30% aqueous phase). The soap solution is then typically dried (e.g. to about 16-18 % water). Soaps formed after saponification and before extrusion to final bar are referred to often as soap “noodles”. The soap noodles and subsequently mixed, milled, plodded (e.g., by extruding the soap noodles through a nose cone), cut and stamped into bars.

[0006] The chain length of fatty acid soaps varies depending on starting fat or oil feedstock (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 ‘nut’ oils, for example, coconut oil or palm kernel oil. The fatty acid soaps produced may also be saturated or unsaturated (e.g., oleic acid soap).

[0007] Typically, longer molecular weight fatty acid soaps (e.g., C14 to C22 soaps) especially longer, saturated soaps are insoluble and do not generate good foam volumes, despite the fact that they can help making the foam generated by other soluble soaps creamier and more stable. Conversely shorter molecular weight soaps (e.g., Cs to C12) and unsaturated soaps (e.g., oleic 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 in that they maintain structure and do 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.

[0008] The palm oil is harvested from the fruit of palm trees. Palm oil is the major source of low chain fatty acids and there has been an endeavor to reduce its usage as Palm Kernel oil is considered bad for the environment. PKO usage has been and continues to be a major driver of deforestation of some of the world's most biodiverse forests, destroying the habitat of already endangered species like the Orangutan, pygmy elephant and Sumatran rhino.

[0009] Typically a bar which is formed by a so-called extruded bar process should be formed from soaps of sufficient hardness (not too mushy as to clog machinery or too nonplastic as to slow rate of production and cause cracking) so the soaps can be extruded at a sufficiently high rate to justify the economics of the bar production. Typically, we define such rate to be at least 200 bars / minute, preferably in excess of 300 bars / minute. To meet the defined extrusion rate standard, applicants have defined a bar hardness which must be met. Typically, the hardness value is between about 3 and 5 kilogram force when measured at 40°C using 15 mm penetration. Measurement of hardness is a measurement of the final bar product after extrusion. Typically, such measurement is taken right after the extrusion.

[0010] To ensure high throughput production of bars upon extrusion, fatty acid soaps (formed from saponification of oils) should neither be too soft (clogging machinery), nor too hard (diminishing extrusion rates due to lower plasticity and / or compromising final bar products due to severe cracking). The properties of the saponified soaps in turn depend on the selection of the oil blend forming the soaps. The oil blend can also be important in determining other properties (e.g., lather, rate of wear, mush) upon soap extrusion and production of final bar. The lather produced by a soap bar is related to the presence of low chain length soaps (C8-C12) and the degree of unsaturation of the soaps.

[0011] A measure of soap bar property is the ratio of high to low chain length amongst the saturated soaps. Low chain length soaps are soluble and hence will render a bar soft. Additionally, it is reported that the Lauric (C12) and Oleic (C18:1) Sodium soaps form a eutectic mix that enhances the lather of a bar but further renders it soft. It is thus important to balance the chain lengths and unsaturation in a bar to obtain the right degree of hardness as well as produce the desired level of lather.

[0012] Superior lather profile (e.g., volume, speed, quality) is the key among all other sensory attributes of a soap bar format. The manifestation of lather in a soap bar is due to soluble soaps (e.g., oleate, C8 to C14 chain length) present in it.

[0013] Shorter chain length soaps (e.g., C8 to C14) are mostly responsible for lather profile in consumer domain. Kernel oils (e.g., palm, coconut etc) of the vegetable seeds are the primary sources of these soaps. Due to deforestation and government regulation on edible oil there is a huge challenges of availability of these oils for soap production. Therefore, it is desirable to produce soap bar with less or nil kernel oil without compromising current soap bar sensory.

[0014] WO2017129472A1 (Unilever) relates to predominantly (50% or greater) soap bars made from oil or oils of defined iodine value. Unexpectedly, it was found that, when 5- 15% of potassium soap was used (as percent of total bar composition), starting oils having IV 37 or below (e.g., 0-37, preferably 2-36, preferably 10-35, more preferably 25-35 even more preferably 30-35) can be used; and the final bars obtained, when resulting soap noodles are extruded, have hardness of 3.0 to 5.0 kg measured at 40°C with excellent extrusion rates (as defined by falling within defined hardness values).

[0015] Our co-pending application EP22206458.6 relates to soap bars made from oil or oils of defined iodine value. The application discloses that when defined amounts of potassium soap are used, bars made from oils falling within a high IV range have excellent extrusion rates (as defined by falling within defined hardness values) without exhibiting the drop in hardness associated with high IV values. The lather of the bars was also seen to be good with low levels of nut oils incorporated in the soap bars.

[0016] The low chain length fractions typically come from the nut oils (palm kernel oils, coconut oil) which are under environmental stress or find use as edible oils. Thus, reducing the levels of these oils in soaps is advantageous from a sustainability viewpoint. As the short chain fatty acids are known to provide lather. Therefore, it is quite a challenge to prepare a soap which gives desirable lather in the absence or with even low amounts of short chain fatty acids.

[0017] Therefore, there is a need to have a soap bar composition that has desirable hardness, lathers well and also reduces environmental stress by using less of short chain length fractions that typically come from the natural oils.

[0018] Summary of the invention

[0019] First aspect of the present invention provides soap bar composition comprising, a. 30 to 75 wt% of total fatty matter (TFM); 2 to 40 wt% of the composition comprises soluble fatty matter; b. 1 to 10 wt% non-soap surfactant c. 12 to 35 wt% water; and d. 2 to 5 wt% electrolyte, wherein the electrolytes comprise up to 30 wt% of class I electrolytes and 30 to 100 wt% class II electrolytes by weight of the electrolyte; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L; wherein 0.5 to 20 wt% of the soap bar composition comprises potassium soap.

[0020] Second aspect of the present invention provides process for manufacture of a soap bar composition according to the first aspect, the method comprising the steps of: a. selecting fatty acids comprising 2 to 40 wt% comprises soluble fatty matter by weight of the soap bar composition; b. saponifying fatty acids of step (a) with alkali to obtain a soap mixture comprising 0.5 to 20 wt% of potassium soap by weight of the soap bar composition; c. adding non-soap surfactant to obtain a soap mass; and d. extruding the soap mass to form a soap bar; wherein 2 to 5 wt% electrolyte by weight of the soap bar composition, are added during step (a) (b) or (c); wherein the electrolytes comprise up to 30 wt% of class I electrolytes and 30 to 100 wt% class II electrolytes; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L.

[0021] Third aspect of the present invention provides use of soap bar composition according to the first aspect to provide soap bars having a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value.

[0022] Fourth aspect of the present invention provides use of soap bar composition according to the first aspect to provide soap bars having stamping rate of at least 100 tablet / min.

[0023] Detailed description of the invention

[0024] 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.

[0025] The present invention relates to a soap composition. By a soap composition it is understood to be a composition which may be used as a soap or a composition which is used to prepare a soap. More preferably the present invention provides a soap composition which is used to prepare soap bars and more preferably extruded soap bars and furthermore preferably soap bars prepared by plough shear mixer. The soap composition of the invention is especially useful for personal cleansing.

[0026] The soap composition of the present invention comprises 30 to 75 wt% of total fatty matter (TFM) 1 to 10 wt% non-soap surfactant; 12 to 35 wt% water; and 2 to 5 wt% electrolyte, wherein the electrolytes comprise up to 30 wt% of class I electrolytes, preferably 0.01 to 30 wt% and 30 to 100 wt% class II, preferably 30 to 99.99, electrolytes by weight of the electrolyte; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L; and wherein 0.5 to 20 wt% of the composition comprises potassium soap.

[0027] The composition of the present invention is preferably used or used to prepare a shaped solid for example a bar. The cleaning soap composition is preferably used or used to prepare a wash off product that generally has sufficient amount 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.

[0028] 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 10%, preferably less than 8%, more preferably less than 7%.

[0029] The soap composition of the invention is capable of stably retaining high amount of water in the range of 10 to 45 wt% as compared to conventional soap composition. Thus, water is preferably at least 10 wt.%, further preferably at least 12 wt.%, still more preferably at least 15 wt.% furthermore preferably at least 17 wt.% but the amount of water in the soap composition is preferably not more than 40 wt.%, still preferably not more than 38 wt.%, most preferably not more than 35 wt.%. In highly preferred aspects, the amount of water in the soap composition ranges from 12 to 35%, more preferably 15 to 33% by weight of the composition.

[0030] There is an intent of the industry and particularly the applicant to reduce the palm kernel oil (PKO) usage in the manufacture of soap for sustainability reasons. PKO is known for lathering properties, PKO is a popular soap making oil. It can be used as the only oil or combined with other oils to increase lather, due to its high content of caprylic, lauric, and myristic acids, which are the low chain fatty acids. The PKO is the major source of low fatty acid chain vegetable oils for a soap. However the lather produced by a soap bar is related to the presence of low chain length soaps (C8-C12) and the degree of unsaturation of the soaps. Therefore, it is mainly the soluble fatty matter, i.e. , Cs to C14 chain fatty acids and unsaturated fatty acids that result in good lather of the soap. Due to sustainability agenda, the inventors of the present invention set out to arrive at a soap bar formulation which reduces the soluble soap content and still performs at par with the conventional soaps. For this reason, some amount of potassium soap and non-soap surfactant was adding by replacing the soluble fatty matter, however this lead to the bar softening and significant stampability issues.

[0031] It was a surprising finding of the present invention that when a certain combination of electrolytes from two categories or classes is used, it solves the problem of bar softening and stampability issues and even resulted in bars with high stamping throughput. Further, without the electrolytes, when starch was tried to be added as a filler to solve the problem of bar softening, it aggravated the processing problems and the plasticy texture of the soap composition. Whereas with the use of the combination of electrolytes of class I and class II according to this invention, incorporation of starch as a filler and even high amount of water was made possible. Further the soap bars did not require stamping at very low temperature and therefore no specific stamping equipment and infrastructure was required for stamping these bars.

[0032] The Soap Bar

[0033] The present invention provides a soap bar composition with good hardness values.

[0034] The composition has bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value. The bar hardness of the soap was good despite high moisture content ranging between 12 to 35% by wt.

[0035] The soap bar of the present invention is a solid shape bar of any shape and is preferably a cleansing soap bar and more preferably a personal cleansing soap bar.

[0036] The soap bar of the present invention comprises a total fatty matter in the range of 30 to 75 wt% by weight of the composition; wherein fatty acid soap comprises 0.5 to 20 wt% of potassium soap by weight of the composition, 2 to 40 wt% of the composition comprises soluble fatty matter and 28 to 45 wt% of insoluble fatty matter.

[0037] Bars of the invention have hardness of at least 3, more preferably in the range of 2.7 to 5 Kg and when measured at 40°C using 15 millimeter penetration.

[0038] Further, final bars preferably have water level of 13 to 35%, preferably 15 to 30 wt% and most preferably 18 to 28 wt% by wt. of bar.

[0039] Fatty Acid Soap

[0040] In general, the term “soap” is used to mean an alkali metal or alkanol ammonium salts of aliphatic, alkane-, or alkene monocarboxylic acids derived from natural triglycerides. Sodium, potassium, magnesium, mono-, di and tri-ethanol ammonium cations, or combinations thereof, are typical counterions of the carboxylic acid. The criticality of using specific amounts of potassium soaps made, and the resulting effects on processing or properties, such as those of our invention, is not previously known. In “typical” bars used in the art, sodium soaps are generally used and, as noted, while potassium, magnesium or triethanolamine soaps are used, the particular criticalities of our invention are not known. In general, the soaps are well known alkali metal salts of natural or synthetic aliphatic (alkanoic or alkenoic) acids having about 8 to about 22 carbon atoms, preferably about 10 to about 18 carbon atoms. They may be described as alkali metal carboxylates having about 8 to about 22 carbon atoms.

[0041] Soaps having the fatty acid distribution of coconut oil may provide the lower end of the broad molecular weight range. The term ‘Nut Oils’ as used herein, refers to fatty acid mixtures having an approximate carbon chain length distribution of 8% Cs, 7% Cw, 48% C12, 17% Ci4, 8% Ci6, 2% Cis, 7% oleic and 2% linoleic acids (the first six fatty acids listed being saturated). Other sources having similar carbon chain length distributions, such as palm kernel oil (PKO) and babassu kernel oil, are usually used in place of or together with coconut oil. This invention aims at minimizing the wt% of these short chain fatty acid oil sources.

[0042] Soap having fatty acid distribution of Palm may present the upper end of the broad molecular weight range. ‘Palm oils’ define fatty acid mixtures which have approximate carbon chain length distribution of 1.5% C14, 41% Ci6, 5% Cis, 42% oleic and 10% linoleic (the first three fatty acids listed being saturated). Other oils with similar distributions can be used in place of or together with palm. For purposes of this invention, this may include oils derived from various animal tallows and lard, as well as oils such as palm stearin oil (PSO) and their hydrogenated forms and derivatives.

[0043] Soaps can be classified into three broad categories which differ in the chain length of the hydrocarbon chain, i.e., the chain length of the fatty acid, and whether the fatty acid is saturated or unsaturated. For purposes of the present invention these classifications are:

[0044] "Lauries" soaps which encompass soaps which are derived predominantly from C12 to C14 saturated fatty acid, i.e. lauric and myristic acid, but can contain minor amounts of soaps derived from shorter chain fatty acids, e.g., Cs & C10.

[0045] "Stearics" soaps which encompass soaps which are derived predominantly from Cw to Cw saturated fatty acid, i.e. palmitic and stearic acid but can contain minor level of saturated soaps derived from longer chain fatty acids, e.g., C20.

[0046] "Oleics" soaps which encompass soaps which are derived from unsaturated fatty acids including predominantly oleic acid (C ), linoeleic acid (C :2), myristoleic acid (Ci4:i) and palmitoleic acid (C ) as well as minor amounts of longer and shorter chain unsaturated and polyunsaturated fatty acids. Nut oils employed for the soap may be substituted in whole or in part by other "high- laurics" or "laurics rich" oils, that is, oils or fats wherein at least 45% of the total fatty acids are composed of lauric acid, myristic acid and mixtures thereof. These oils are generally exemplified by the tropical nut oils of the coconut oil class and their forms and derivatives. For instance, they include: palm kernel oil, babassu oil, ouricuri oil, tucum oil, cohune nut oil, murumuru oil, jaboty kernel oil, khakan kernel oil, dika nut oil, and ucuhuba butter.

[0047] When a solid mass which includes a mixture of laurics, stearics and oleics soaps is heated, the laurics and oleics soaps, which are more water soluble and have lower melting points than stearics soaps, combine with water and other components present in the composition to form a more or less fluid liquid crystal phase depending on water content and temperature. This transformation of laurics and oleics soaps form a solid to a liquid crystal phase provides plasticity to the mass which allows it to be mixed and worked under shear, i.e. the mass is thermoplastic.

[0048] The soap bar composition according to the present invention it is preferable that the starting oil or fatty acid is selected from a plant or animal-based source. It is preferable that that the starting oil or fatty acid is selected from palm oil, palm kernel oil, soya bean oil, rice bran oil, tallow oil, coconut oil and fractions and mixtures thereof. It is furthermore preferable that the starting oil or fatty acid are obtained from the oil distillates and / or fractionates of oil or fatty acid.

[0049] When the soap composition of the present invention is for personal washing application it comprises 30 to 75 wt% total amount of soap, preferably 32 to 73 wt%, more preferably 35 to 70 wt% and most preferably 45 to 68 wt% by weight of the soap composition.

[0050] The term soap means salt of fatty acid. Preferably, the soap is soap of C8 to C24 fatty acids.

[0051] 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.

[0052] The soap may be obtained by saponification of oils, fats or fatty acids. The fats or oils generally used to make soap compositions 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.

[0053] 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.

[0054] The soap compositions of the present invention preferably include about 2 to 40 wt% of soap composition is the soluble fatty matter which include low molecular weight soaps (C8 to C14 soaps) and unsaturated soaps. The soap compositions of the present invention comprise 30 to 70 wt%, more preferably 30 to 50 wt% of total soluble fatty matter are low molecular weight or short chain fatty acid based soaps (C8 to C14 soaps) and 30 to 70 wt% of total soluble fatty matter are unsaturated soaps. Unsaturated soaps are preferably oleic acid or linoleic soaps.

[0055] It is preferred that the soap composition includes 28 to 45 wt% of the water insoluble fatty matter which are preferably soaps of C16 and higher fatty acid chain. It is preferred that the soap compositions comprise 30 to 45 wt%, and most preferably 33 to 45 wt% of long fatty acid chain fatty matter of C16 and higher fatty acid chain by weight of the soap bar composition.

[0056] It is preferred that in the soap composition of the present invention wherein the class I electrolytes comprise sodium chloride and sodium sulphate.

[0057] It is preferred that in the soap composition of the present invention wherein the class I electrolytes comprise sodium chloride in the range of 0.1 to 3 wt%. It is preferred that in the soap composition of the present invention wherein the class I electrolytes comprise sodium sulfate in the range of 0.1 to 3 wt%.

[0058] It is preferred that in the soap composition of the present invention the class II electrolytes comprise compounds selected from the group of sodium citrate, sodium carbonate, sodium tartrate, disodium maleate, and sodium oxalate or mixtures thereof.

[0059] It is preferred that in the soap composition of the present invention the soap composition comprises 2 to 40 wt% of fatty matter from Cs to C14 chain fatty acids or unsaturated fatty acids.

[0060] It is preferred that in the soap composition of the present invention the soap composition comprises 28 to 45 wt% of fatty matter higher than C16 chain fatty acids and more preferably C16 to C18 fatty acids by the weight of the soap.

[0061] It is preferred that in the soap composition of the present invention the composition comprises polymeric form of silica in the range of 2 to 10wt%.

[0062] It is preferred that in the soap composition of the present invention the composition comprises polymeric form of sodium alumino silicate in the range of 2 to 10wt%.

[0063] It is preferred that in the soap composition of the present invention the composition has a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value.

[0064] Potassium soaps

[0065] The present invention comprises fatty acid soap comprises 0.5 to 20 wt% of potassium soap by weight of the composition, preferably 1 to 15 wt% and more preferably 5 to 10 wt% and even more preferably 5 to 9 wt% and most preferably 5.5 to 8.5 wt% by weight of the composition.

[0066] When starting oils are saponified, it is preferable that at least that 0.5 to 20 wt% potassium soap be formed. The exact amount, within this range, is readily ascertainable by calibrating using the hardness value test. By ensuring correct window of production of potassium soap noodles (and more specifically, the correct range or amount within this window and which can be readily determined by those skilled in the art).

[0067] Water

[0068] The soap compositions of the present invention can hold a good amount of moisture or water content. The soap compositions of the present invention have 12 to 35 wt% of water, preferably 15 to 30 wt%, more preferably 18 to 28 wt% and most preferably 20 to 28wt% of water by weight of the soap composition.

[0069] Electrolyte

[0070] 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.

[0071] It is preferred that composition of the invention comprises 2 to 5 wt%, preferably 2 to 4.5 wt %, more preferably in the range of 2.8 to 4 wt % electrolyte, and most preferably 2.8 to 3.8% by weight of the composition.

[0072] It is preferred that in the composition of the invention the electrolytes comprise up to 30 wt% of class I electrolytes, preferably 0.01 to 30wt%, more preferably 0.1 to 30wt%, and even more preferably 1 to 30 wt%, and 30 to 100 wt% class II electrolytes, preferably 30 to 99.99 wt%, more preferably 30 to 99.9 and most preferably 30 to 99 wt% by weight of the total electrolyte; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L. The term ‘up to’ 30 wt% preferably means less than 30wt% of class I electrolytes and 30 wt% or more than 30 wt% of class II electrolytes, or at least 30wt% of class II electrolytes of the total electrolytes.

[0073] It is preferred that the 30 to 100 wt% of the total electrolytes have ionic strength of at least 0.22 mole ions / L. It is preferred that class II electrolytes are at most 99.99 wt%, more preferably at most 99.9 wt% and most preferably at most 99 wt% by weight of the composition.

[0074] Ionic strength of the aqueous solution of an electrolyte is measured at 1 wt% of electrolyte using mathematical equation (i) available in any standard physical chemistry. 1% aqueous electrolyte solution refers to an aqueous solution containing 99% of water and 1% of electrolyte which is dissolved and dissociates into ions completely.

[0075] Where

[0076] “I” is ionic strength of the aqueous solution

[0077] “c” molar concentration of the respective cations and anions from the electrolytes “z” valency of the respective cations and anions from the electrolytes

[0078] It is preferred that the the class II electrolytes are selected from the group of sodium citrate, sodium carbonate, sodium tartrate, disodium maleate, potassium carbonate and sodium oxalate.

[0079] It is preferred that the remaining class I electrolytes up to 30wt%, preferably 0.01 to 30wt%, more preferably 0.1 to 30wt%, and even more preferably 1 to 30 wt%, more preferably from 0.0001 to 29.9999 wt%, more preferably from 0.01 to 29.99 wt%, further more preferably from 0.1 to 29.9 wt% and most preferably from 1 to 29wt% of the total weight of electrolytes are selected from the group of include sodium sulfate, sodium chloride, 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 and non-surfactant material. It is preferred that class I electrolytes comprise sodium chloride and sodium sulphate. It is preferred that the class I electrolytes comprise sodium chloride in the range of 0.1 to 3 wt% by weight of the soap bar composition. It is preferred that the class I electrolytes comprise sodium sulfate in the range of 0.1 to 3 wt% by weight of the soap bar composition.

[0080] It is preferred that in class I electrolytes, when sodium sulphate is present in the range of 0.5 to 1.5 wt% of the weight of composition, more preferably 0.7 to 1.3 and most preferably 1 to 1.3 wt%. It is preferred that sodium sulphate is at least 0.5 wt%, more preferably at least 0.7wt%, and most preferably at least 1wt% and it is preferred that it is not more than 3wt%, more preferably not more than 2.5 wt%, furthermore preferably not more than 2wt% and most preferably not more than 1 ,5wt% by weight of the soap bar composition.

[0081] It is preferred that that in class I electrolytes, when sodium chloride is present in the range of 0.5 to 1.5 wt% of the weight of composition, more preferably 0.7 to 1.3 and most preferably 1.0 to 1.3 wt%. It is preferred that sodium chloride is at least 0.5 wt%, more preferably at least 0.6 wt%, and most preferably at least 0.7 wt% and it is preferred that it is not more than 3wt%, more preferably not more than 2.5 wt%, and further, more preferably not more than 2wt% and most preferably not more than 1 ,5wt% by weight of the soap bar composition.

[0082] Non-soap surfactant

[0083] In addition to the soap of fatty acids, preferred bars may include a non-soap surfactant, which acts as a co-surfactant and which is selected from anionic, non-ionic, zwitterionic, amphoteric and cationic surfactants.

[0084] The present invention comprises non-soap surfactant in the range of 1 to 10wt%, more preferably 1 to 8 wt% and most preferably 2 to 7 wt% by weight of the soap composition.

[0085] Preferred bars include 0.0001 to 15 wt% co-surfactants based on the weight of the composition. More preferred bars include 2 to 10 wt% co-surfactant and most preferred compositions include 2.5 to 6 wt% co-surfactant based on the weight of the composition. 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.

[0086] 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. 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.

[0087] 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.

[0088] 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. 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.

[0089] 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.

[0090] 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.

[0091] 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-(dodecylmethyl sulphonium) propane-1 -sulphonate betaine and 3- (cetylmethylphosphonium) ethane sulphonate betaine. 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.

[0092] Other preferred ingredients In addition to the ingredients described earlier, preferred cleansing bar may include other ingredients.

[0093] A preferred bar may include up to 30 wt% benefit agents. Preferred benefit agents are moisturizers, emollients, sunscreens 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.

[0094] Examples of moisturizers and humectants include cetyl alcohol, CARBOPOL® 934, 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. 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 UV-A and UV-B sun-screens may also be added. 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. Structurants such as maltodextrin or starch may be used to structure the bars. Preferred bars may also include essential oils such as bergamot and citrus or insoluble extracts of avocado, grape, grapeseed, myrrh, cucumber, watercress, calendula, elder flower, geranium, linden blossom, amaranth, seaweed, gingko, ginseng and other plant extracts. Further optional ingredients include chelating agents such as ethylene diamine tetra acetic acid, preservatives (e.g. GLYDANT ®) antioxidants, and natural and synthetic perfumes. Cationic polymers may be included as conditioners. These include POLYQUATERNIUM ® , MERQUAT ® polymers, and JAGUAR ® polymers. The composition can also optionally include other ingredients conventionally used in soap such as lather boosters, hemectants such as glycerine, moisturisers, colourants and opacifiers. 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%. Other optional ingredients like anti-oxidants, perfumes, polymers, chelating agents, colourants, deodorants, dyes, emollients, moisturizers, enzymes, foam boosters, germicides, antimicrobials, 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 and before filtering. Sodium metabisulphite, ethylene diamine tetra acetic acid (EDTA), borax and ethylene hydroxy diphosphonic acid (EHDP) are preferably added to the formulation.

[0095] It is preferred that the cleansing bar has no or essentially no opacifiers. By opacifiers is meant compounds which limit the quantity of light passing through the solid composition. When opacifiers are present, the solid composition is generally opaque, i.e. "opacification". Examples of opacifiers include titanium dioxide, zinc oxide and the like.

[0096] The soaps bar composition may optionally comprise 0.1 to 15%, preferably 0.2 to 12% by weight of free fatty acids. By free fatty acids is meant a carboxylic acid comprising a hydrocarbon chain and a terminal carboxyl group bonded to an H. Suitable fatty acids are C8 to C22 fatty acids. Preferred fatty acids are C12 to C18, preferably predominantly saturated, straight-chain fatty acids. However, some unsaturated fatty acids can also be employed.

[0097] 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. Most preferred polyol is glycerol. In a preferred embodiment, the bars of the invention comprise 0 to 8%, preferably 1 to 7.5% by wt. polyol.

[0098] The various optional ingredients that make up the final soap composition are as described below:

[0099] The total level of the adjuvant materials used in the bar composition generally is in an amount not higher than 50%, preferably 1 to 50%, more preferably 3 to 45% by wt. of the soap composition.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] Examples of other optional insoluble inorganic particulate materials include aluminates, silicates, phosphates, insoluble sulfates, borates and clays (e.g., kaolin, china clay) and their combinations.

[0105] Organic particulate materials include: insoluble polysaccharides such as highly crosslinked or insolubilized starch (e.g., by reaction with a hydrophobe such as octyl succinate) and cellulose; synthetic polymers such as various polymer lattices and suspension polymers; insoluble soaps and mixtures thereof.

[0106] It is preferred that the compositions of the invention comprise polymers. Polymers of the acrylate class are especially preferred. Preferred bars include 0.05 to 5% acrylates. More preferred bars include 0.01 to 3% acrylates. Examples of acrylate polymers include polymers and copolymers of acrylic acid crosslinked with polyallylsucrose as described in US Patent 2,798,053 which is herein incorporated by reference. Other examples include polyacrylates, acrylate copolymers or alkali swellable emulsion acrylate copolymers, hydrophobically modified alkali swellable copolymers, and crosslinked homopolymers of acrylic acid. Examples of such commercially available polymers are: ACULYN®, CARBOPOL®, and CARBOPOL® Ultrez grade series.

[0107] 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.

[0108] 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.

[0109] The product can take the form of a water-clear, i.e. transparent soap, in which case it will not contain an opacifier.

[0110] The pH of preferred soaps compositions of the invention is from 8 to 11 , more preferably 9.5 to 11.

[0111] A preferred bar may additionally include up to 30 wt% benefit agents. Preferred benefit agents include moisturizers, emollients, sunscreens 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. Other optional ingredients like anti-oxidants, perfumes, polymers, chelating agents, colourants, deodorants, dyes, enzymes, foam boosters, germicides, anti-microbials, lathering agents, pearlescers, skin conditioners, stabilizers or superfatting agents, 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.

[0112] The composition of the invention could be used to deliver antimicrobial benefits. Antimicrobial agents that are preferably included to deliver this benefit 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 or 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.

[0113] In soap compositions for laundering fabric, one or more of the above described optional ingredients may be included. However, in laundry bars, antimicrobial agents are generally not added. Laundry bars generally include chelating agents that are generally not included in soap compositions for personal cleansing. Chelating agents may be selected from but not limited to ethylene diamine tetra acetic acid (EDTA), ethylene hydroxy diphosphonic acid (EHDP) or mixtures thereof. The chelating agent is preferably present in an amount ranging from 0.01 wt.% to 1 wt.%. Non-phosphate chelating agents like methylglycinediacetic acid and salts thereof are also preferred.

[0114] The present invention provides use of soap bar composition according to the first aspect to provide soap bars having a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value.

[0115] Process

[0116] In a second aspect, the present invention relates to a process to prepare a soap composition of the first aspect comprising the steps of: a. selecting fatty acids comprising 2 to 40 wt% of soluble fatty matter by weight of the soap composition and ; b. saponifying fatty acids of step (a) with alkali to obtain a soap mixture comprising

[0117] 0.5 to 20 wt% of potassium soap of the total soap composition; c. adding non-soap surfactant to obtain a soap mass; and d. extruding the soap mass to form a soap bar; wherein 2 to 5 wt% electrolyte, are added during step (a) (b) or (c); wherein the electrolytes comprise up to 30 wt% of class I electrolytes and 30 to 100 wt% class II electrolytes; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L.

[0118] It is preferred in the process of the present invention that the non-soap surfactant is added in the range of 1 to 10 wt% by weight of the soap bar composition.

[0119] It is preferred in the process of the present invention that the class I electrolyte comprise sodium chloride and sodium sulphate.

[0120] It is preferred in the process of the present invention that the class I electrolyte comprise sodium chloride in the range of 0.1 to 3 wt% by weight of the soap bar composition. It is preferred in the process of the present invention that the that the class I electrolyte comprise sodium sulphate in the range of 0.1 to 3 wt% by weight of the soap bar composition.

[0121] It is preferred that in the process of the present invention the class II electrolyte comprises a compound selected from the group of sodium citrate, sodium carbonate, sodium tartrate, disodium maleate, potassium carbonate and sodium oxalate.

[0122] It is preferred in the process of the present invention that the soap composition comprises 2 to 40 wt% of total fatty matter from C8 to C14 chain fatty acids or unsaturated fatty acids by weight of the soap bar composition .

[0123] It is preferred in the process of the present invention that the fatty acid soap comprises 28 to 45 wt% of fatty matter from C16 and higher chain fatty acids by weight of the soap bar composition.

[0124] It is preferred in the process of the present invention that the composition comprises polymeric form of silica in the range of 2 to 10 wt% by weight of the soap bar composition.

[0125] It is preferred in the process of the present invention that the composition comprises polymeric form of sodium alumino silicate in the range of 2 to 10 wt% by weight of the soap bar composition.

[0126] It is preferred in the process of the present invention that TFM of the soap composition is 30 to 72 wt% by weight of the soap bar composition.

[0127] It is preferred in the process of the present invention that the composition has a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value.

[0128] 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 composition, compositions thus prepared by extrusion are found to be easy to stamp with a desirable indicia. By “easy to extrude” is meant that the hardness of the bar as it is extruded is high enough that it exits the extruder in a firm enough form that it can be called a rigid bar. The hardness of the bar is preferably higher than 1.2 kg, more preferably in the range of 1.2 to 5.0 kg (at 40°C). The hardness is preferably measured using the TA-XT Express apparatus available from Stable Micro Systems. The hardness is measured using this apparatus with a 30° conical probe - Part #P / 30c to a penetration of 15 mm. If the soap mass is too soft and is passed through the extruder it will not extrude out of the extruder in a cohesive enough mass to be called a bar. By “easy to stamp” is meant that the soap composition is of such a consistency and low enough stickiness that it does not stick to the die that is used to stamp any desired indicia on the bar. The soap composition prepared by the process of the invention therefore preferably comprises an indicium stamped thereupon.

[0129] The specific process that may be employed using the above described general process for soap composition manufacture comprises one of the following processes.

[0130] The present invention also provides use of soap bar composition according to the first aspect to provide soap bars having a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value.

[0131] The present invention also provides use of soap bar composition according to the first aspect to provide soap bars having stamping rate of at least 100 tablet / min.

[0132] EXAMPLES

[0133] Example 1- Soap Compositions

[0134] The soap compositions for the examples were prepared in accordance with the present invention. Bars were prepared in two step process. First, high moisture noodle with potassium soap were prepared, Non soap surfactant and electrolytes and 2ndconverting the noodle into finished goods by mixing minors (perfume, colorant etc), milling, plodding, cutting and stamping. The oils for the examples were procured from Indonesia. Following steps were executed to prepare High moisture noodles: 1ststep

[0135] Required quantity of DFA / Oil was taken in a soap neutralizer PSM / Crutcher and electrolytes of both Class I and Class II added either powder form or solution form. Part of the oil Saponification or DFA neutralization first started with required quantity of KOH solution to generate potassium soap and then complete saponification reaction with NaOH solution. Non-soap surfactant and glycerin were added into it and allowed for 5- 10 min of mixing. Required quantity of process water was then added. The composition converted into noodle passing through chill drum and noodler.

[0136] Following steps were executed to prepare High moisture noodles: 2ndstep

[0137] The noodles as prepared in the first step were crushed in a mixer and added colorant, benefit agents and fillers like starch, talc, perfume. Mixer mass through triple roll mill, refiner, plodder and extruded in the shape of billet. Hardness, moisture were measured in this step. The billet was cut into definite sizes and stamped on an automated operated continuous stamper where chilled water was passed through upper and lower die set to manipulate stamping speed. The bars from stamper are stamped.

[0138] Control composition E1 was prepared with 71 TFM with sodium carbonate as electrolyte. Compositions E2, E3, and E4 were 45 TFM soaps with 43 IV value having sodium chloride and sodium sulfate as electrolytes of class I and prepared in accordance with the method of present invention. E2, E3 and E4, differed in class II electrolytes, sodium oxalate was used in E2, sodium citrate in E3, and sodium carbonate in E4. Whereas, in composition E5, none of the class II electrolytes were used. In E6, an additional electrolyte sodium lactate from class I category was used in addition to sodium sulphate and sodium chloride but none from class II electrolytes were used.

[0139] Table 1

[0140] The data presented in the table show that when the specific combination of electrolytes are used from class I and class II according to the present invention like in E2, E3, E4, despite high moisture level, presence of potassium soap, high level of non-soap surfactant and presence of starch and even low level of soluble soaps, the resultant soap bars high stamping throughput rate, good ploddability, bar hardness and even did not require sophisticated stamping infrastructure at low temperatures. Whereas in E5 and E6, though the lather was comparable, when electrolytes of class II were not used, the bars were ploddable, but could not be continuously stamped even by lowering the die set temperature upto -13°C. The stamping rate of 40 tablets / min for this example at pilot scale is co-related to minimum 100 tablet / min stamping speed at factory scale processing.

[0141] Therefore it is clear that soap bars with the combination of electrolytes according to the present invention of acceptable hardness, high stamping throughput rate, good lather and ease of processibility can be achieved which have low level of soluble soaps or low chain fatty acid soaps and high moisture content. Hardness Testing Protocol

[0142] Principle

[0143] A 30° conical probe penetrates into a soap / syndet sample at a specified speed to a pre-determined depth. The resistance generated at the specific depth is recorded. There is no size or weight requirement of the tested sample except that the bar / billet be bigger than the penetration of the cone (15mm) and have enough area. The recorded resistance number is also related to the yield stress and the stress can be calculated as noted below. The hardness (and / or calculated yield stress) can be measured by a variety of different penetrometer methods. In this invention, as noted above, we use probe which penetrates to depth of 15 mm.

[0144] Apparatus and Equipment

[0145] TA-XT Express (Stable Micro Systems)

[0146] 30° conical probe - Part #P / 30c (Stable Micro Systems)

[0147] Sampling Technique

[0148] This test can be applied to billets from a plodder, finished bars, or small pieces of soap / syndet (noodles, pellets, or bits). In the case of billets, pieces of a suitable size (9 cm) for the TA-XT can be cut out from a larger sample. In the case of pellets or bits which are too small to be mounted in the TA-XT, the compression fixture is used to form several noodles into a single pastille large enough to be tested.

[0149] Procedure

[0150] Setting up the TA-XT Express

[0151] These settings need to be inserted in the system only once. They are saved and loaded whenever the instrument is turned on again. This ensures settings are constant and that all experimental results are readily reproducible.

[0152] Set test method

[0153] Press MENU

[0154] Select TEST SETTINGS (Press 1)

[0155] Select TEST TPE (Press 1) Choose option 1 (CYCLE TEST) and press OK

[0156] Press MENU

[0157] Select TEST SETTINGS (Press 1)

[0158] Select PARAMETERS (Press 2)

[0159] Select PRE TEST SPEED (Press 1)

[0160] Type 2 (mm s-1) and press OK

[0161] Select TRIGGER FORCE (Press 2)

[0162] Type 5 (g) and Press OK

[0163] Select TEST SPEED (Press 3)

[0164] Type 1 (mm s-1) and press OK

[0165] Select RETURN SPEED (Press 4)

[0166] Type 10 (mm s-1) and press OK

[0167] Select DISTANCE (Press 5)

[0168] Type 15 (mm) for soap billets or 3 (mm) for soap pastilles and press OK

[0169] Select TIME (Press 6)

[0170] Type 1 (CYCLE)

[0171] Calibration

[0172] Screw the probe onto the probe carrier.

[0173] Press MENU

[0174] Select OPTIONS (Press 3)

[0175] Select CALIBRATE FORCE (Press 1) - the instrument asks for the user to check whether the calibration platform is clear

[0176] Press OK to continue and wait until the instrument is ready.

[0177] Place the 2kg calibration weight onto the calibration platform and press OK

[0178] Wait until the message “calibration completed” is displayed and remove the weight from the platform.

[0179] Sample Measurements

[0180] Place the billet onto the test platform.

[0181] Place the probe close to the surface of the billet (without touching it) by pressing the UP or DOWN arrows.

[0182] Press RUN

[0183] Take the readings (g or kg) at the target distance (Fin). After the run is performed, the probe returns to its original position.

[0184] Remove the sample from the platform and record its temperature.

[0185] Calculation & Expression of Results

[0186] Output

[0187] The output from this test is the readout of the TA-XT as “force” (RT) in g or kg at the target penetration distance, combined with the sample temperature measurement. (In the subject invention, the force is measured in Kg at 40°C at 15 mm distance)

[0188] The force reading can be converted to extensional stress, according to the equation given below.

[0189] The equation to convert the TX-XT readout to extensional stress is where: o = extensional stress

[0190] C = "constraint factor" (1.5 for 309cone)

[0191] Gc= acceleration of gravity

[0192] A = projected area of cone d = penetration depth

[0193] 0 = cone angle

[0194] For a 30° cone at 15 mm penetration, Equation 2 becomes a (Pa) = RT (9) X 128.8

[0195] This stress is equivalent to the static yield stress as measured by penetrometer.

[0196] The extension rate is: where t = extension rate (s-1)

[0197] V = cone velocity

[0198] For a 30° cone moving at 1mm / s, E = 0.249 s-1 Temperature Correction

[0199] The hardness (yield stress) of skin cleansing bar formulations is temperature-sensitive. For meaningful comparisons, the reading at the target distance (RT) should be corrected to a standard reference temperature (normally 40°C), according to the following equation:

[0200] R40 = R x exp[a(T-40)] where R40 = reading at the reference temperature (40°C)

[0201] RT = reading at the temperature T a = coefficient for temperature correction

[0202] T = temperature at which the sample was analyzed.

[0203] The correction can be applied to the extensional stress.

[0204] Raw and Processed Data

[0205] The result is the temperature-corrected force or stress, but it is advisable to record the instrument reading and the sample temperature also.

[0206] A hardness value of at least 1.2 kg (measured at 40°C), preferably at least 2.7 kg is acceptable.

Claims

Claims1. A soap bar composition comprising, a. 30 to 75 wt% of total fatty matter (TFM); 2 to 40 wt% by weight of the soap bar composition comprises soluble fatty matter; b. 1 to 10 wt% non-soap surfactant; c. 12 to 35 wt% water; and d. 2 to 5 wt% electrolyte, wherein the electrolytes comprise 0.01 to 30 wt% of class I electrolytes and 30 to 99.99 wt% class II electrolytes by weight of the electrolyte; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L; wherein 0.5 to 20 wt% of the soap bar composition comprises potassium soap; wherein soluble fatty matter is selected from unsaturated fatty acids and C8 to C14 fatty acids at 30°C; wherein, the ionic strength of the aqueous solution of the electrolyte is measured at 1wt% of electrolyte according to to the equation:f' where“I” is ionic strength of the aqueous solution“c” molar concentration of the respective cations and anions from the electrolytes “z” valency of the respective cations and anions from the electrolytes.

2. A composition according to claim 1 , wherein the class I electrolytes comprise sodium chloride.

3. A composition according to claim 1 or 2, wherein the class I electrolytes comprise sodium sulphate.

4. A composition according to anyone of claims 1 to 3, wherein the class I electrolytes comprise sodium chloride in the range of 0.1 to 1.5 wt% by weight of the soap bar composition.

5. A composition according to anyone of the preceding claims 1 to 4, wherein the class I electrolytes comprise sodium sulphate in the range of 0.1 to 1.5 wt% by weight of the soap bar composition.

6. A composition according to anyone of the preceding claims 1 to 5, wherein the class II electrolytes comprise a compound selected from the group of sodium citrate, sodium carbonate, sodium tartrate, disodium maleate, potassium carbonate and sodium oxalate or mixtures thereof.

7. A composition according to anyone of the preceding claims 1 to 6, wherein the fatty acid soap comprises 28 to 45 wt% of fatty matter from chains higher than Ci6 fatty acids by weight of the soap bar composition.

8. A composition according to anyone of the preceding claims 1 to 7, wherein the composition comprises polymeric form of silica in the range of 2 to 10wt% by weight of the soap bar composition.

9. A composition according to anyone of the preceding claims 1 to 8, wherein the composition comprises polymeric form of sodium alumino silicate in the range of 2 to 10wt% by weight of the soap bar composition.

10. A soap bar composition according to anyone of the preceding claims 1 to 9, wherein the composition has a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value, wherein the hardness is measured according to the method in the description.

11. A process for manufacture of a soap bar composition according to claims 1 to 10, the method comprising the steps of: a. selecting fatty acids comprising 2 to 40 wt% soluble fatty matter by weight of the soap bar composition;b. saponifying fatty acids of step (a) with alkali to obtain a soap mixture comprising 0.5 to 20 wt% of potassium soap by weight of the soap bar composition; c. adding non-soap surfactant to obtain a soap mass; and d. extruding the soap mass to form a soap bar composition; wherein 2 to 5 wt% electrolyte by weight of the soap bar composition, are added during step (a) (b) or (c); wherein the electrolytes comprise 0.01 to 30 wt% of class I electrolytes and 30 to 99.99 wt% class II electrolytes; wherein the class II electrolytes have ionic strength of at least 0.22 mole ions / L and class I electrolytes have ionic strength of less than 0.22 mole ions / L.

12. Use of soap bar composition according to claims 1 to 10 to provide soap bars having a bar hardness of 2.7 to 5.0 Kg when measured at 40°C, using 15 mm penetration value, wherein the hardness is measured according to the method in the description.

13. Use of soap bar composition according to claims 1 to 10 to provide soap bars having factory scale stamping rate of at least 100 tablet / min.

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