Field of the invention

The invention relates to bars which are predominantly fatty acid soap bar compositions. The invention relates to bars prepared from oil stock of high IV and low short chain (C8-C14) content with defined levels of potassium soaps incorporated in the bar.

Background of the invention

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, plam 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.

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., C palmitic or C 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).

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. 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 non-plastic 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.

The hardness of the final bar correlates with the iodine value of the oil forming the soap. Oils and fats which have a high average level of unsaturation are said to have high iodine value; and oils and fats which have a low average level of unsaturation are said to have low iodine value. Typically, bars made from oils with higher iodine value (more unsaturated) are softer and those made from oils with low IV value (more saturated) are harder. Iodine value is a well- known standard for measuring unsaturation and measurement of IV is well known and understood. One well known method, for example, is use of gas chromatography. Using this method, methyl esters of the fatty acid chains in the oil are formed and methyl esters of the fatty acids are analysed by gas chromatography. As noted, this is well known in the art.

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.

The iodine value (IV) of a soap bar is a measure of average level of unsaturated fatty acid chains making up the triglycerides. A high IV soap is more soluble and hence renders a soap bar soft. The other measure of soap bar property is the ratio of high to low chain length amongst the saturated soaps. Low chain length soaps are again 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. 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).

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.

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.

Summary

First aspect of the present invention provides a soap bar composition comprising a fatty acid soap in the range of 30 to 90 wt% by weight of the composition; wherein fatty acid soap comprises 1 to 20 wt% of potassium soap by weight of the composition, and wherein starting oil or fatty acid of the fatty acid soap has an average Iodine value in the range of 35 to 50.

Second aspect of the present invention provides a process for manufacture of a soap bar composition extrudable at rate of 200 or more bars per minute, the method comprising the steps of: (a) selecting oil or fatty acid having an Iodine value in the range of 35 to 50; (b) saponifying the oil with potassium hydroxide to provide potassium soap; and (c) combining 1 to 20 wt% of the soap resulting from step b), based on the weight of the resulting soap bar, with additional ingredients and extruding the resulting mixture to obtain a soap bar.

Third aspect of the present invention provides use of starting oil or fatty acid of the fatty acid soap has an average Iodine value in the range of 35 to 50 in manufacture of soap bars according to the first aspect, having kgF value between 3 and 4 by the method herein provided in the description. Detailed description of the invention

Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about.”

As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as terminus of the range.

The use of and/or indicates that any one from the list can be chosen individually, or any combination from the list can be chosen.

For the avoidance of doubt, 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.

Unless indicated otherwise, all percentages for amount or amounts of ingredients used are to be understood to be percentages by weight based on the weight of the material in the total weight of the composition, wherein total is 100%.

It has been a finding of the inventors of the present invention that soap bars can be made from starting oils having high iodine values (IV) in combination with low levels of C8-C12 chains with high extrusion rates while simultaneously maintaining excellent user properties (good lather; lower cracking); typically, bars with higher IV (higher level of unsaturation) and low chain lengths have superior user properties, but do not have high throughput extrusion (e.g., because they are too soft). However, it was observed that surprisingly, by providing a specific wt% of potassium soap to bars prepared from oils of defined IV and chain length distribution, bars having hardness values which provide ideal extrusion rates can be prepared while simultaneously maintaining good lather.

The IV of starting oil or fatty acids is achieved by mixing oils of different IV values or by using blends of oils and hydrogenated oil.

Unexpectedly, it has been found 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. This is a unique and unexpected simultaneous accumulation of attributes. Further, the soaps of the present invention were able to achieve the desired hardness despite a water content of 16 to 20% by wt.

Unexpectedly, applicants have found that, a blend of high IV with low level of short chain soaps can be used to get the desired level of hardness. The lather of these bars was enhanced by incorporating 1 to 20 % of potassium soaps.

While inclusion of potassium soap which is more soluble and low chain length fatty acid soaps both are known to make a soap bar softer and mushy, and on the other hand the lowering of IV in fatty acid soap is again known to cause a mush and affect the consumer desirable characteristics such as lather and foaming. It was a high unexpected finding of the present invention that the soap bar according to the first aspect of the present invention is able to show good of 3.0 to 5.0 Kg when measured at 40°C, using 15 mm penetration value and lathering property.

The present invention provides a soap bar composition comprising a fatty acid soap in the range of 30 to 90 wt% by weight of the composition; wherein fatty acid soap comprises 1 to 20 wt% of potassium soap by weight of the composition, and wherein starting oil or fatty acid of the fatty acid soap has an average Iodine value in the range of 35 to 50.

The composition of the present invention uses low or negligible amounts of nut oils such as palm kernel oils and coconut oils which are the source of short chain low chain length fractions and which are under environmental stress. Therefore, the present invention has found a way to make soap bars of desirable hardness and lather properties whilst retaining the moisture content and using negligible amount of nut oils.

The Soap Bar

The present invention provides a soap bar composition with good hardness values. The composition has bar hardness of 3.0 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 18 to 25% by wt.

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.

The soap bar of the present invention comprises a fatty acid soap in the range of 30 to 90 wt% by weight of the composition; wherein fatty acid soap comprises 1 to 20 wt% of potassium soap by weight of the composition, and wherein starting oil or fatty acid of the fatty acid soap has an average Iodine value in the range of 35 to 50.

Bars of the invention have hardness of at least 3, more preferably in the range of 3 to 4 KgF and when measured at 40°C using 15 millimeter penetration.

Further, final bars preferably have water level of 13 to 20%, preferably 16 to 19 wt% by wt. of bar.

Fatty Acid Soap

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.

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% C10, 48% C12, 1 % C14, 8% CIB, 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.

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% C , 5% C , 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. 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:

"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.

"Stearics" soaps which encompass soaps which are derived predominantly from C to C 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.

"Oleics" soaps which encompass soaps which are derived from unsaturated fatty acids including predominantly oleic acid (Cis:i), linoeleic acid (Ci8:2), myristoleic acid (Ci4:i) and palmitoleic acid (Cie:i) 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.

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.

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. It is preferable that the soap bar composition according to the present invention, wherein the fatty acids of the soap from nut oil are in the range of 0 to 20wt%, more preferably 1 to 15wt% and most preferably 2 to 10 wt% of the weight of total fatty acids in the soap.

It is preferable that the soap bar composition according to the present invention, wherein the fatty acids of the soap from non-nut oil (Palm/Tallow) or hydrogenated forms and derivatives thereof is in the range of 80 to 100 wt%, more preferably 85 to 99wt% and most preferably 90 to 98 wt% of the weight of total fatty acids in the soap.

As noted, level of fatty acid soap in the bar is 30% or greater, preferably 35% or greater. The fatty acid soap in the composition of the present invention is in the range of 30 to 90 wt%, more preferably 40 to 70 wt% and most preferably in the range of 45 to 70 wt% by weight of the composition.

Preferably, the bar is extruded from soaps and the soaps are formed by saponification of starting oil or oils having an average iodine value of 35 to 50, preferably 37 to 48, preferably 38 to 47 and most preferably 40 to 46.

It is preferable that the fatty acids of the soap having starting oil or fatty acid is selected from non-nut oil and forms and derivatives thereof is 80 to 100 wt% of the total fatty acids.

It is preferable that the fatty acids of the soap having starting oil or fatty acid is selected from nut oil forms and derivatives thereof is at most 20wt% of the total fatty acids.

Potassium Soap

The present invention comprises fatty acid soap comprises 1 to 20 wt% of potassium soap by weight of the composition, most preferably 1 to 15 wt% and most preferably 5 to 13 wt% by weight of the composition.

When starting oils are saponified, it is preferable that at least that 1 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), this unexpectedly permits use of starting oil or oils having iodine value of 37 to 50, much higher than what would have been thought required in order to have good hardness value

Moisture content The bars comprise water at level of 10 to 25% by wt. Lower level of water may be 16 or 17 or 18% and upper level may be 22, 23 or 24%.

Electrolytes

The level of electrolytes should be less than 3.0%, preferably less than 2%, Electrolytes could include Na-Chloride, Na-Sulphate, Na-Citrate, Na-Carbonate or the corresponding Potassium Salts.

Optional Ingredients

Surfactants other than soap (commonly known as "synthetic surfactants" or "syndets") can optionally be included in the bar at levels generally up to and including about 10%, preferably at levels between about 2% to about 7% by weight of the bar. Examples of suitable syndets are described below.

The bar may include structurants. These may include one or more polysaccharide structurants selected from the group consisting of starch, cellulose and their mixtures; one or more polyols; and optionally, a water insoluble particulate material. Structurants may, individually or combined, support 0 to 25% by wt. of bar composition.

Suitable starch materials include natural starch (from corn, wheat, rice, potato, tapioca and the like), pregelatinzed starch, physically and chemically modified starch and mixtures thereof. By the term natural starch, also known as raw or native starch, is meant starch which has not been subjected to further chemical or physical modification apart from steps associated with separation and milling.

A preferred starch is natural or native starch (commonly also known as raw starch) from maize (corn), cassava, wheat, potato, rice and other natural sources. Raw starch with different ratio of amylose and amylopectin include: maize (25% amylose); waxy maize (0%); high amylose maize (70%); potato (23%); rice (16%); sago (27%); cassava (18%); wheat (30%) and others. The raw starch can be used directly or modified during the process of making the bar composition such that the starch becomes either partially or fully gelatinized.

Another suitable starch is pre-gelatinized which is starch that has been gelatinized before it is added as an ingredient in the present bar compositions. Various forms are available that will gel at different temperatures, e.g., cold water dispersible starch. One suitable commercial pregelatinized starch is supplied by National Starch Co. (Brazil) under the trade name FARMAL CS 3400 but other commercially available materials having similar characteristics are suitable. Suitable cellulose materials include microcrystalline cellulose, hydroxyalkyl alkylcellulose ether and mixture thereof.

A preferred cellulose material is microcrystalline cellulose (a highly crystalline particulate cellulose made primarily of crystalline aggregates) which is obtained by removing amorphous fibrous cellulose regions of a purified cellulose source material by hydrolytic degradation. This is typically done with a strong mineral acid (e.g., hydrogen chloride). The acid hydrolysis process produces microcrystalline cellulose of predominantly coarse particulate aggregates, typically of mean size range 10 to 40 microns. One suitable commercial microcrystalline cellulose is supplied by FMC Biopolymer (Brazil) under the trade name AVICEL GP 1030 but other commercially available materials having similar characteristics are suitable.

A preferred polysaccharide structurant is starch, most preferably a natural starch (raw starch), a pre-gelatinized starch, a chemically modified starch or mixtures thereof. Raw starch is preferred.

Polyol is a term used herein to designate a compound having multiple hydroxyl groups (at least two, preferably at least three) which is highly water soluble, preferably freely soluble, in water.

Many types of polyols are available including: relatively low molecular weight short chain polyhydroxy compounds such as glycerol and propylene glycol; sugars such as sorbitol, manitol, sucrose and glucose; modified carbohydrates such as hydrolyzed starch, dextrin and maltodextrin, and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG).

Preferred polyols are relatively low molecular weight compound which are either liquid or readily form stable highly concentrated aqueous solutions, e.g., greater that 50% and preferably 70% or greater by weight in water. These include low molecular weight polyols and sugars.

Especially preferred polyols are glycerol, sorbitol and their mixtures.

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 MgsSi4 (O)IO(OH)2, and may be available in the hydrated form. Talc has a plate-like morphology, and is substantially oleophilic/ hydrophobic.

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. Commercially, calcium carbonate or chalk (precipitated calcium carbonate) is produced by a carbonation method in which carbon dioxide gas is bubbled through an aqueous suspension of calcium hydroxide. In this process the crystal type of calcium carbonate is calcite or a mixture of calcite and aragonite.

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

Organic particulate materials include: insoluble polysaccharides such as highly cross-linked or insolubilized starch (e.g., by reaction with a hydrophobe such as octyl succinate); synthetic or natural polymers such as various polymer lattices and suspension polymers and mixtures thereof.

The bars may comprise anti-cracking agents such as carboxymethylcellulose, acrylate polymers and their mixtures.

In terms of possible optional ingredients, various additional electrolytes (in addition to the fatty acid soap and other charged surfactants which are electrolyte), especially those having alkali metal cations can be present in the bar. These electrolytes are present either as a result of saponification and neutralization of the fatty acids, e.g., NaCI generated from saponification with sodium hydroxide and neutralization with hydrochloric acid, or as added salts such as sodium or potassium sulfate which may be used to control hardness. Various electrolytes can be used in modest amounts as long as they are not strong detergent builders or otherwise interfere with the efficacy of the anti-cracking agents.

The bar compositions can optionally include non-soap synthetic type surfactants (detergents) - so called "syndets". Syndets can include anionic surfactants, nonionic surfactants, amphoteric or zwitterionic surfactants and cationic surfactants.

The level of synthetic surfactant, individually or combined, present in the bar is generally not greater than about 10% in the continuous phase although inclusion of higher levels in the bar may be advantageous for some applications. Some embodiment of the invention includes syndets at a level of about 2% to 10%, preferably about 4% to about 10%.

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%.

Slip modifiers are particularly useful in bar compositions which contain starch/cellulose and/or insoluble particles whose levels approach the higher end of the useful concentration range for these materials, e.g., 30-40% for starch with 5-10% insoluble particulate material. It has been found that the incorporation of higher levels of starch and/or insoluble particles increases the wet skin friction of the bar and the bars are perceived as "draggy" (have a high perceived level of frictional "drag" on the skin). Although some consumers do not mind this sensory quality, while others dislike the sensation. In general, consumers prefer bars that are 20 perceived to glide easily over their skin and are perceived as being slippery.

It has been found that certain hydrophobic materials incorporated at low levels can dramatically reduce the wet skin frictional drag of bars containing higher levels of starch and/or insoluble particles to improve consumer acceptability.

Suitable slip modifier include petrolatum, waxes, lanolines, poly-alkane, -alkene, -polyalkalyene oxides, high molecular weight polyethylene oxide resins, silicones, polyethylene glycols and mixtures thereof.

Particularly suitable slip modifiers are high molecular weight polyethylene oxide homopolymer resins having molecular weights of from about 100,000 to about 7,000,000. The polymers have a degree of polymerization from about 2,000 to about 100,000. These polymers are available as white powders.

Preferably the molecular weight of the polyethylene oxide resin is greater than 80,000, more preferably at least 100,000 Daltons and most preferably at least 400,000 Daltons. Examples of suitable high molecular weight polyethylene oxide resins are water soluble resins supplied by Dow Chemical Company under the trade name POL VOX. An example is WSR N-301 (molecular weight 4,000,000 Daltons).

Adjuvants are ingredients that improve the aesthetic qualities of the bar especially the visual, tactile and olefactory properties either directly (perfume) or indirectly (preservatives). A wide variety of optional ingredients can be incorporated in bars of the current invention. Examples of adjuvants include but are not limited to: perfumes; opacifying agents such as fatty alcohols, ethoxylated fatty acids, solid esters, and Ti02; dyes and pigments; pearlizing agent such as Ti02 coated micas and other interference pigments; plate like mirror particles such as organic glitters; sensates such as menthol and ginger; preservatives such as dimethyloldimethylhydantoin (Glydant XL 1000), parabens, sorbic acid and the like; antioxidants such as, for example, butylated hydroxy toluene (BHT); chelating agents such as salts of ethylene diamine tetra acetic acid (EDTA) and trisodium etridronate (provided it is present at less than about 0.3%); emulsion stabilizers; auxiliary thickeners; buffering agents; and mixtures thereof.

The level of pearlizing agent, if present, should be between about 0.1 % to about 3%, preferably between 0.1 % and 0.5% and most preferably between about 0.2 to about 0.4% based on the total weight of the composition.

Adjuvants are commonly collectively designated as "minors" in the soap making art and frequently include at a minimum, colorant (dyes and pigments), perfume, preservatives and residual salts and oils from the soap making process, and various emotive ingredients such as witch-hazel. Minors generally constitute 4 to 10% by weight of the total continuous phase composition, preferably 4 to 8%, and often about 5-7% of the continuous phase.

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% will lead to soft and sticky mass and will negatively impact in bar quality. 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% by wt.

A particular class of optional ingredients highlighted here is skin benefit agents included to promote skin and hair health and condition. Potential benefit agents include but are not limited to: lipids such as cholesterol, ceramides, and pseudoceramides; antimicrobial agents such as TRICLOSAN; sunscreens such as cinnamates; exfoliant particles such as polyethylene beads, walnut shells, apricot seeds, flower petals and seeds, and inorganics such as silica, and pumice; additional emollients (skin softening agents) such as long chain alcohols and waxes like lanolin; additional moisturizers; skin-toning agents; skin nutrients such as vitamins like Vitamin C, D and E and essential oils like bergamot, citrus unshiu, calamus, and the like; water soluble or insoluble extracts of avocado, grape, grape seed, myrrh, cucumber, watercress, calendula, elder flower, geranium, linden blossom, amaranth, seaweed, gingko, ginseng, carrot; impatiens balsamina, camu camu, alpina leaf and other plant extracts such as witch- hazel, and mixtures thereof.

The composition can also include a variety of other active ingredients that provide additional skin (including scalp) benefits. Examples include anti-acne agents such as salicylic and resorcinol; sulfur-containing 0 and L amino acids and their derivatives and salts, particularly their N-acetyl derivatives; anti-wrinkle, anti-skin atrophy and skin-repair actives such as vitamins (e.g., A,E and K), vitamin alkyl esters, minerals, magnesium, calcium, copper, zinc and other metallic components; retinoic acid and esters and derivatives such as retinal and retinol, vitamin B3 compounds, alpha hydroxy acids, beta hydroxy acids, e.g. salicylic acid and derivatives thereof; skin soothing agents such as aloe vera, jojoba oil, propionic and acetic acid derivatives, fenamic acid derivatives; artificial tanning agents such as dihydroxyacetone; tyrosine; tyrosine esters such as ethyl tyrosinate and glucose tyrosinate; skin lightening agents such as aloe extract and niacinamide, alpha-glyceryl-L-ascorbic acid, aminotyroxine, ammonium lactate, glycolic acid, hydroquinone, 4 hydroxyanisole, sebum stimulation agents such as bryonolic acid, dehydroepiandrosterone (DHEA) and orizano; sebum inhibitors such as aluminum hydroxy chloride, corticosteroids, dehydroacetic acid and its salts, dichlorophenyl imidazoldioxolan (available from Elubiol); anti-oxidant effects, protease inhibition; skin tightening agents such as terpolymers of vinylpyrrolidone, (meth)acrylic acid and a hydrophobic monomer comprised of long chain alkyl (meth)acrylates; anti-itch agents such as hydrocortisone, methdilizine and trimeprazine hair growth inhibition; 5-alpha reductase inhibitors; agents that enhance desquamation; anti-glycation agents; anti-dandruff agents such as zinc pyridinethione; hair growth promoters such as finasteride, minoxidil, vitamin D analogues and retinoic acid and mixtures thereof.

Regardless of the optional agent or agents employed, their level should be chosen such that the composition is an extrudable mass (penetrometer hardness of 3 to 5 Kg kPa measured at a temperature of 40°C; preferably bars should have yield stress of 350 to 2000 kPa) and the bars derived from the composition conveniently have a Cracking Index of 3 or less. Cracking Index is based on a scale in which the degree of cracking can be visually observed (see Figure 4) as described in the protocol. The yield stress referred to is the static yield stress. It is equivalent to extensional stress and is calculated, as set forth in the protocol section below, also using penetrometer device.

The benefit agent bars of the invention further preferably comprise essential oils.

Essential oil is intended to encompass natural or synthetic fragrances, including natural oil synthetic perfumes. It may be a substance selected from perfume, terpene, terpenoid, various other essential oils (which may include antimicrobial essential oil or an active thereof, or a mixture thereof), or a synthetic compound having odoriferous properties, especially selected from aldehydes, esters, ketones, ionones, ethers and alcohols. If a perfuming substance, it can be a complex perfume composition containing a mixture of various terpenes, terpenoids, essential oils, synthetic odoriferous or more pure compounds. In solution, the weight percentage of said perfuming composition or substance may be between 1% to 10%, and especially from 3% to 10%, and being in particular approximately equal to 5% or approximately equal to 10% (wt. % of total bar).

’’Odoriferous” means a detectable substance olfactively by a subject and/or by olfactormetry according to known principles of art. An exemplary method for the detection of an odoriferous substance is described in EP 0003088. Other detection techniques of an odoriferous substance are applicable as the chromatography techniques in a gas phase spectroscopy of Niasse or yet infrared absorption analysis.

By “terpenes” is meant hydrocarbons wherein the base member is isoprene, their molecular formula comprising a multiple number of carbons 5, particularly terpenes particularly containing 10 to 15 carbon atoms, used in perfumery.

By “terpenoid” means derivatives of terpenes, for example, alcohols, phenols, ketones, aldehydes, esters, ethers.

The following list of odoriferous compounds provided for illustrative purposes, is by no means exhaustive: terpenes pirene, camphene, limonene, cadinene, hull, caryophyliene, alcohols: linolool, geraniol, menthol, citronellol, ketones, menthione, carvone, beta-ionone, thujone, camphor, cyclopertadecanone aldehyde: citral, citrannal, citronellal, cinnamic alkehyde, lilial, esters: linalyl acetate, methyl acetate, getranyl acetate, geranyl succinates, phenols, thymol, carvacrol, eugenol, isoeugenol, ethers: anthole, eucalyptol, cineol, rose oxide.

Essential oils can be oils of yiang-yiang, bergamot, eucalyptus, lavender, lavender, lemongrass, patchouli, peppermint, pine, rose, coriander, Shiu, of sage, geranium, palmarosa, Litsea cubeba, lemon, lemongrass, orange blossom, grapefruit, lime, mandarin, tangerine, orange, cajeput, camphor, rosemary, d anise, star anise, fennel, basil, tarragon, clove, pepper, thyme, sassafras, wormwood, mugwort, cedar, hyssop. Tagetes of street, elemi, galbanum, juniper berries, cabreuva, guaiac wood, sandalwood, vetiver, ambrette, angelica, orris rhizome, carrot, celery, cumin, lovage, parsley, cinnamon, cardamom, ginger, nutmeg, pepper, frankincense, myrrh, balsam of Peru, styrax, buchu, chamomile or cistus (Jean Garnero, “Essential oils” engineering techniques, physic-chemical constants Treaty, K-345).

Typical perfumery material which may form part of, or possibly the whole of, the active ingredient include natural essential oils such as lemon oil, mandarin oil, clove leaf oil, petitgrain oil, cedar wood oil, patchouli oil, lavandin oil, neroli oil, ylang oil, rose absolute or jasmine absolute, natural resins such as labdalium resin or olibanun resin; single perfumery chemicals which may be isolated from natural sources or manufactured synthetically, as for example alcohols such as geraniol, nerol, citronellol, linalool, tetrahydro- geraniol, betaphenylethyl alcohol, methyl phenyl carbinol, dimethyl benzyl carbinol, -menthol or cedrol; acetates and other esters derived from such alcohols; aldehydes such as citral, citronellal, -hydroxy- citronellal, lauric aldehyde, undecylenic-aldehyde, cinnamaldehyde, amyl cinnamic aldeyde, vanillin or heliotropin; acetals derived from such aldehydes; ketones such as methyl hexyl ketone, the ionones and the methylionones; phenolic compounds such as eugenol and isoeugenol; synthetic musks such as musk xylene, musk ketone and ethylene brassylate; and other materials commonly employed in the art of perfumery. Typically at least five, and usually at least ten, of such materials will be present as components of the active ingredient.

Besides fragrance material, volatile insecticides, bacteriocides, pheronones and fabric softeners can also usefully be incorporated.

As noted, antimicrobial essential oils and actives thereof, or mixture may be used.

Such antimicrobial essential oils include, but are not limited to, those obtained from thyme, lemongrass, citrus, lemons, orange, anise, clove, aniseed, pine, cinnamon, geranium, roses, mint, lavender, citronella, eucalyptus, peppermint, camphor, ajowan, sandalwood, rosmarin, vervain, fleagrass, lemongrass, ratanhiae, cedar and mixtures thereof. Preferred antimicrobial essential oils to be used herein are thyme oil, clove oil, cinnamon oil, geranium oil, eucalyptus oil, peppermint oil, citronella oil, ajowan oil, mint oil or mixtures thereof.

Actives of essential oils which may be used herein include, but are not limited to, thymol (present for example in thyme, ajowan), eugenol (present for example in cinnamon and clove), menthol (present for example in mint), geraniol (present for example in geranium and rose, citronella), verbenone (present for example in vervain), eucalyptol and pinocarvone (present in eucalyptus), cedrol (present for example in cedar), anethol (present for example in anise), carvacrol, hinokitiol, berberine, ferulic acid, cinnamic acid, methyl salicylic acid, methyl salycilate, terpineol, limonene and mixtures thereof. Preferred actives of essential oils to be used herein are thymol, eugenol, verbenone, eucalyptol, terpineol, cinnamic acid, methyl salicylic acid, limonene, geraniol or mixtures thereof.

Thymol may be commercially available for example from Aldrich - Manheimer Inc, eugenol may be commercially available for example from Sigma, Systems - Bioindustries (S81) - Manheimer Inc.

Preferably, the antimicrobial essential oil or active thereof or mixture thereof is present in the composition at a level up to 20% by weight of the total composition, preferably at a level of at least 0.003% to 10%, more preferably from 0.006% to 10%, even more preferably from 0.01 % to 8% and most preferably from 0.03% to 3%.

Method

The process for manufacture of a soap bar composition having hardness value so that it may be extruded at rate of 200 or more bars per minute and a cracking value of 0 to 3, the method comprising the steps of (a) selecting oil or fatty acid having an Iodine value in the range of 35 to 50; (b) saponifying the oil with potassium hydroxide to provide potassium soap; and (c) combining 1 to 20 wt% of the soap resulting from step b), based on the weight of the resulting soap bar, with additional ingredients and extruding the resulting mixture to obtain a soap bar.

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. Preferably the soap bar composition of the present invention is prepared using the extrusion route. Preferably using a crutcher/Mazzonni/spray drier process or a Sigma mixer process (Post dosing route).

Neutralizing fatty acid or fats to form fatty acid soap:

The fatty acids used for neutralization may be of a single type or a mixture of different fatty acids. Preferably the fatty acids are a mixture of different fatty acids. The fats used are a combination of those which provide the preferred amounts of short chain fatty molecules and long chain fatty molecules. As used herein the term fats also includes oils as is generally known to the person skilled in the art. The neutralization step is achieved by using an alkaline neutralizing agent preferably selected from silicate, carbonate, hydroxide, alkaline aluminium- containing material such as aluminate, a phosphate or mixtures thereof to form fatty acid soap, preferably the alkaline neutralizing agent is a hydroxide or silicate. Still preferably the alkaline neutralizing agent used for neutralization is sodium hydroxide or potassium hydroxide. The process of the invention comprises the first step of heating to 60 to 80°C, a fat blend comprising lauric fatty acid and saturated and unsaturated non-lauric fatty acids in a blend tank, where iodine value of the fat blend is from 35-50 g/lodine per 100g. The main parts of a typical mixer are a jacketed barrel, axial rotating shaft through the centre of the barrel (longitudinally), plough-shaped blades mounted on the axial shaft, and chopper. The ploughs and the highspeed chopper are the mixing elements. Since the gap between the plough surface and the barrel is about 3 to 8 mm, the material gets sheared significantly while mixing. A typical mixer has barrel volume of 60 litres, plough rpm of 200 and chopper rpm of 3000. The plough area to barrel volume is approximately 0.002 cm ^-1 .

About a third of the blend from the melting tank is then transferred into the blend tank maintained at 60 to 80°C.

The process may alternatively be carried out in any mixer conventionally used in soap manufacture. Preferably a high shear kneading mixer is used. The preferred mixers include kneading members of sigma type, multi wiping overlap, single curve or double arm. The double arm kneading mixers can be of overlapping or tangential in design. Alternatively, the invention can be carried out in a helical screw agitator vessel or multi head dosing pump/high shear mixer and spray drier combinations as in conventional processing.

The next step involves adding an alkali, preferably under shearing action, to saponify the fat blend. The saponification is preferably carried out to the extent of 80 to 100 %. Preferably an aqueous solution or dispersion of the alkali is used. More preferably the alkali is caustic soda. Alternatively, any other suitable alkali may be used in stoichiometric amount which can be calculated easily. Temperature of the reaction mass increases due to exothermic nature of the saponification reaction. Preferably a portion of the total alkali is introduced into the mixer in an aqueous form.

Crutcher process:

Step (i): This is one of the well-known processes for preparing a soap bar composition. In the crutcher process the step of neutralizing one or more fatty acid or fat with an alkaline neutralizing agent to obtain fatty acid soap is carried out by adding the fatty acid or fats with the preferred ratio ranges of fatty acid with shorter chain length of C12 or below and fatty acids with longer chain length of C14 or higher in the crutcher which is maintained at a temperature of 50°C to 90°C. The oils used may be selected from distilled fatty acids or neutral oils. Next an alkaline neutralizing agent preferably sodium hydroxide or potassium hydroxide is added in an amount required for achieving complete saponification of the fatty acids or fat. Thereafter the temperature of crutcher is increased to a range from 75°C to 120°C. Preferably during the neutralizing step a desired amount of sodium carbonate or sodium chloride solution is added to the neutralizing mixture to obtain the fatty acid soap. During the step of neutralizing the fatty acid or soap or immediately thereafter preferably a chelating agent is also added. Non-limiting examples of the chelating agent includes the EHDP and EDTA.

Drying: The dough mass formed is preferably dried in the next step. In this drying step, the dough mass is dried to reduce the moisture content of the mix to 15 wt.% to 20 wt.%. The drying step on a commercial basis may be achieved by several different methods. One procedure employs a water-chilled roll in combination with a second feed roll to spread molten, neutralized soap into a thin, uniform layer. The cooled dough mass is then scraped from the roll to form chips and dried to a specific moisture level in a tunnel dryer. A modern technique for the drying is known as spray drying. This process directs molten dough mass to the top of a tower via spray nozzles. The dough mass sprayed to form dried soap mix hardens and then dries in the presence of a current of heated air. Vacuum may be applied to facilitate removal of water, preferably the vacuum of at least 50 mm Hg absolute pressure is provided. The dried soap mix is then extruded to form soap noodles. During the drying step generally 4 wt.% to 7 wt.% of the moisture is removed from the dough mass. Preferably the drier is a mazzoni vacuum spray drier which is maintained at a temperature of 85°C to 90°C and the vacuum is maintained at 700 mm Hg and the flow rate is around 3 to 8 tonnes per hour.

Plodding: Preferably after drying, in dough mass is subjected to mixing, milling and plodding step. In the plodding, the step involves converting the soap noodles into a shaped soap bar composition. The plodder used is a dual stage twin screw plodder that allows for a vacuum of about 40 to 65 mm Hg between the two stages. The soap log extruded from the plodder is cut into individual plugs. These plugs are then preferably stamped on a conventional soap stamping apparatus to yield the finished shaped soap bar composition. After stamping the finished soap bar is packaged in desired packaging material which may be selected from laminate, films, paper or combinations thereof.

In a preferred process, prior to plodding the dried soap noodles may be subjected to an amalgamating step carried out in a simple paddle-type mixer where the noodles are added to an amalgamator in which adjunct ingredients such as colorants, preservatives, perfume are added and mixed thoroughly to combine all the ingredients together. Further to this, the mix from the amalgamator may be preferably subjected to a milling step. In the three-roll soap mill the amalgamated mixture is passed through the rolls set at a temperature from 29°C to 41 °C to obtain a homogenous mix, This, is an intimate mixing step where the soap mix is subjected to compression and an intense shearing action. After mixing in the mill the mix is transferred to the plodder.

Sigma mixer (Post dosing) process:

In an alternate process, the soap noodles comprising purely Sodium Soap are added into the sigma mixer. This is followed by addition of potassium soaps flakes or needles intpo the sigma mixer. The Potassium soap could be Potassium laurate, Myristate, Palmitate etc and the mixer is operated for preferably 10 to 15 minutes to homogenize.

The present invention provides use of starting oil or fatty acid of the fatty acid soap has an average Iodine value in the range of 35 to 50 in manufacture of soap bars according to the first aspect, having kgF value between 3 and 4 by the method herein provided in the description.

The invention will now be illustrated by means of the following non-limiting examples.

EXAMPLES

Example 1

The soaps for the examples were prepared according to the method given above. For examples E1- E17- Sigma mixer (Post dosing) process was used and for examples E18 to E22, Plough shear mixer was used. The oils for the invention were sourced from Indonesia.

Table 1 : Soap Composition

Example 2: Soap Bar Compositions in absence of Nut Oil Table 2- Compositions in absence of nut oil - Effect of IV

Table 3- Compositions in absence of nut oil - Effect of Potassium Soap Level at fixed IV

The data presented in tables 2 and 3 indicate that even in absence of nut oils, potassium soaps give acceptable lather and hardness within the IV range of 35 to 50. The soap bar was very hard and could not be processed at a IV of < 35.

Example 3: Soap Bar Compositions in presence of 10% Nut Oil

Table 4 - Compositions with 10% Nut Oil - Effect of IV The data presented in table 3 indicates that even in presence of 10wt% nut oils, potassium soaps give acceptable lather and hardness within the IV range of 35 to 50. The lather balance can be achieved by an optimal mix of IV and potassium soap.

Example 4: Soap Bar Compositions in presence of 15% Nut Oil

Table 5 - Compositions with 15% Nut Oil - Effect of IV

The data presented in table 4 indicates that even in presence of 15wt% nut oils, potassium soaps give acceptable lather and hardness within the IV range of 35 to 50.

Protocol

1) Hardness

Hardness Testing Protocol

Principle

A 30° conical probe penetrates into a soap/syndet sample at a specified speed to a predetermined 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. Apparatus and Equipment

TA-XT Express (Stable Micro Systems)

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

Sampling Technique

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.

Procedure

Setting up the TA-XT Express

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.

Set test method

Press MENU

Select TEST SETTINGS (Press 1)

Select TEST TPE (Press 1)

Choose option 1 (CYCLE TEST) and press OK

Press MENU

Select TEST SETTINGS (Press 1)

Select PARAMETERS (Press 2)

Select PRE TEST SPEED (Press 1)

Type 2 (mm s ^-1 ) and press OK

Select TRIGGER FORCE (Press 2)

Type 5 (g) and Press OK

Select TEST SPEED (Press 3)

Type 1 (mm s ^-1 ) and press OK

Select RETURN SPEED (Press 4)

Type 10 (mm s ^-1 ) and press OK

Select DISTANCE (Press 5)

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

Select TIME (Press 6)

Type 1 (CYCLE)

Calibration

Screw the probe onto the probe carrier.

Press MENU

Select OPTIONS (Press 3)

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

Press OK to continue and wait until the instrument is ready. Place the 2kg calibration weight onto the calibration platform and press OK

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

Sample Measurements

Place the cut billet after the extrusion (maximum 30 min) onto the test platform.

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

Press RUN

Take the readings (g or kg) at the target distance (Fin).

After the run is performed, the probe returns to its original position.

Remove the sample from the platform and record its temperature.

Calculation & Expression of Results

Output

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)

The force reading can be converted to extensional stress, according to Equation 2.

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

C = “constraint factor” (1.5 for 30° cone) G _c = acceleration of gravity

. . . ,

K = projected area of _r cone d = penetration depth 0 = cone angle

For a 30° cone at 15 mm penetration Equation 2 becomes ct (Pa) = R _T (g) x 128.8

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

The extension rate is where E = extension rate (s ^-1 )

V = cone velocity

For a 30° cone moving at 1mm/s, E = 0.249 s' ¹

Temperature Correction

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:

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

RT = reading at the temperature T a = coefficient for temperature correction T = temperature at which the sample was analyzed.

The correction can be applied to the extensional stress.

Raw and Processed Data

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

NOTES:

Water hardness, as noted above, should be constant for a series of tests and should be recorded. Where possible, it is preferable to adhere to suitable water hardness. For example, bars which will be used in soft water markets should ideally be tested with soft water (e.g., lower end of French hardness scale).

It is important to keep the number of rubs/twists constant.