GB2459093A - Personal washing soap bar - Google Patents

Abstract

An extruded and stamped personal washing bar comprising: a) 45% to 60% of a fatty acid soap; b) from 0.3% to less than 1.5% of one or more added soluble salts of monovalent cations; c) less than 5.0% of a fatty acid; and d) a structuring system comprising: i) from 5.0% to 14% of a polyol selected from the group consisting of glycerol, sorbitol and their mixtures, ii) from 6% to 25% of a starch, and iii) 0 to 10% of water insoluble particles, wherein the sum of the weights of the polyol, starch and inorganic particles comprises at least about 20% but no more than 30% of the bar by weight-, and wherein the bar composition is an extrudable mass having a yield stress between 350 and 2000 kPa measured at a temperature of 40° C.

Description

EXTRUDED SOAP BARS COMPRISING A STARCH-POLYOL

STRUCTURING SYSTEM

FIELD OF THE INVENTION

The invention relates to personal washing bars that are made by high speed extrusion and stamping and are suitable for the mass market. The bars include a starch-polyol structuring system to replace soap and have excellent in-use properties.

BACKGROUND

Soap bars are widely used around the world for cleansing the body. The use of soap for hygiene is well know and is a key component in fighting the spread of communicable diseases. To accelerate the penetration of soap usage in developing countries, manufacturers have sought ways to reduce the cost of soap bars so as to make them more affordable to low income consumers.

Surfactants (soap, synthetic or a mixture) are generally the predominant ingredient in the bar and contribute the most to total cost of materials. Furthermore, since soaps are predominantly composed of fatty acid salts derived from triglycerides, their costs are rising because of the growing demands of triglycerides as foods and recently as alternative fuels. Consequently, there is an ongoing need to develop personal washing bars in which surfactant, especially soap, is replaced by natural and sustainable ingredients without compromising efficient manufacture and in-use properties of the bars so as to maintain or improve their affordability.

Surfactants are generally the predominant ingredient of personal washing bars and account for the majority of the raw materials cost. When the predominant surfactant in the bar is soap, a reduction in surfactant is commonly expressed as a reduction in "total fatty matter" or TFM. The term TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soaps without taking into account the accompanying cations. The measurement of TFM is well known in the art.

A significant fraction of the surfactants are insoluble solids that provide structure to the bar. Consequently, one strategy that has been used to reduce surfactant content is to replace part of the surfactant by inorganic or organic solids that will form a network.

This non-soap network allows the water level in the bar to be increased from a level of 13-16% which is typical of freshly made bars to 20 to 30% and even greater than 50% in some cases. Examples of various structuring approaches based on this concept are discussed below.

WO 01/42418 to Chokappa et al discloses a detergent bar containing 0.5 to 30% amorphous alumina, one alkali metal salt of carboxylic/sulfonic acid, 5-70% detergent active and 10-55% water.

US 6,207,636 to Benjamin et al discloses detergent bars having 25-70% total fatty matter, include: 9-16% by weight colloidal aluminum hydroxide and 12-52% water.

The invention also comprises a process for preparing a detergent bar.

WO 2006/094586 to Gangopadhayay et al discloses a low TFM detergent bar including soap (15 % to 30 % TFM); 25 % to 70 % inorganic particulates including talc and calcium carbonate; 0.5 % to 10 % of alumino-silicate; and 3 % to 20 % water.

us 6,310,016 to Behal et al discloses a detergent bar including soap (15-70% total fatty matter); 0.5-40% colloidal aluminium hydroxide-phosphate complex, and 10- 50% water. A process for making such bars is also disclosed.

US 6,440,908 to Racherla discloses high moisture containing bar compositions that includes a borate compound. The borate compound structures water in the bar thereby enabling the retention of high amounts of moisture without compromising bar pro perties.

WO 2005/080541 to Gangopadhayay et al discloses a non-granular solid cleaning composition comprising 50 % to 70% of a salt of fatty acid; I % to 15 % of a mono or disaccharide; and 0.02 % to 2 % of a stabilising agent. Preferred saccharides are glucose, sucrose, mannose, and fructose and the stabilizing agent is preferably chosen from the class of fungicides including formaldehyde, benzeic acid and salts thereof and methyl or ethyl paraben.

WO 03/010272 to Anderson et al discloses soap or detergent bar having relatively low levels of total fatty matter (40% to 78%), allowing relatively high levels of water (7% to 30%) and/or other liquid additives to be present by incorporating aluminium hydroxide and tetra sodium pyrophosphate decahydrate into the bar.

Methods of producing such bars are also disclosed.

WO 96/35772 to Wise et al discloses laundry bar compositions including from about 20 % to about 70 % surfactant; from about 12 % to about 24 % water; from about 6.25 % to about 20 % calculated excess alkali metal carbonate; from about 2 % to about % water-soluble inorganic strong-electrolyte salt; and various optional ingredients including whole-cut starch.

WO 95/26710 to Kacher et al discloses personal washing bar compositions that include: about 5 parts to about 40 parts of a lipid skin moisturizing agent: about 10 parts to about 50 parts of a rigid crystalline skeleton network structure consisting essentially of selected fatty acid soap or a mixture of said soap and selected fatty acid; about I part to about 50 parts of a lathering synthetic surfactant, and; about 10 parts to about 50 parts water.

W098/1 8896 to Rahamann et al discloses high moisture laundry bar composition including from about 45 % to about 95 % structured soap composition, wherein said structured soap composition comprises a premixture of: from about 45 % to about 75 % soap; from about 5 % to about 50 % starch; about 25 % to about 45 % moisture; and wherein the ratio of starch to moisture in said structured soap composition is from about 1:5 to about 1.25:1; and from about I % to about 15% synthetic anionic surfactant; wherein the total moisture in the finished bar composition is from about 20 % to about 40%.

US 2007/0021314 and US 2007/0155639 to Salvadoret al disclose cleansing bar compositions having high water content that include (a) at least about 15%, by weight of the composition, of water; (b) from about 40% to about 84%, by weight of the composition, of soap; and (c) from about 1% to about 15%, by weight of the composition, of inorganic salt. The bar compositions further comprise a component selected from the group consisting of carbohydrate structurant, free fatty acid, synthetic surfactants, and mixtures thereof. The bar compositions preferably have a Water Activity ("Aw") of less than about 0. 95, preferably less than about 0.90, and more preferably less than about 0.85. The bar compositions are preferably manufactured by a milling process.

The present invention is the result of extensive experimentation investigating the use of an alternative structuring system the combination of starch with specific polyols and optionally water insoluble particles can allow substantial reductions in surfactant content without having to rely on the inclusion of high levels of water that characterize prior art approaches. Surprisingly, superior bars which have excellent processing characteristics in currently available processes can be obtained.

SUMMARY OF INVENTION

The personal washing bars of the invention are extruded and preferably stamped bars suitable for mass market applications. The personal washing bar includes: a) 45% to 60% of a fatty acid soap; b) from 0.3% to less than 1.5% of one or more added soluble salts of monovalent cations; c) 0 to less than 5.0% of a fatty acid; and d) a structuring system comprising: i) from 5.0% to 14% of a polyol selected from the group consisting of glycerol, sorbitol and their mixtures, ii) from 6% to 25% of a starch, and iii) 0 to 10% of water insoluble particles, wherein the sum of the weights of the polyol, starch and water insoluble particles comprises at least about 20% but no more than 30% of the bar by weight; and wherein the bar composition is an extrudable mass having a yield stress between 350 and 2000 kPa measured at a temperature of 40° C. In one embodiment, the optional insoluble particles are inorganic particulates.

In another embodiment the amount of the one or more insoluble salts is at least 0.3% but less than 1.0%, preferably less than 0.8% based on the total weight of the bar composition.

In another embodiment, the bar composition includes a synthetic surfactant at a level of up to about 10% by weight of the bar. preferably between 2% and 8% by weight.

In still another embodiment, the bar composition includes a slip modifier which greatly improves the feel of the wet bar when it is rubbed on the skin especially when the starch and/or insoluble particles are present in the bar at levels approaching the upper limits of their useful concentration ranges.

In still another embodiment, the bar composition contains less than 20% water, preferably between 14% and 19% water by weight when the bar is initially manufactures, i.e., immediately after it is extruded and stamped.

These and other embodiments are described more fully below in the following written description and various embodiments that are illustrated in the examples.

DETAILED DESCRIPTION OF INVENTION

As used herein % or wt % refers to percent by weight of an ingredient as compared to the total weight of the composition or component that is being discussed (generally the total bar composition).

Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about." All amounts are by weight of the final composition, unless otherwise specified.

It should be noted that in specifying any range of concentration, any particular upper concentration can be associated with any particular lower concentration.

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, options, or alternatives need not be exhaustive.

The present invention relates to extruded personal washing bars that comprise specific levels of fatty acid soaps; one or more added soluble salts; optional fatty acid; from about 20% to no more than 30% of a structuring system; and various other optional ingredients. These components of the bar composition are and method used to manufacture and evaluate the bars are described below.

The bar compositions of the invention are capable of being manufactured at high production rates by processes that generally involve the extrusion forming of ingots or billets, and stamping or molding of these billets into individual tablets, cakes, or bars.

By capable of high manufacturing rates is meant that the mass formed from the bar composition is capable of i) being extruded at a rate in excess of 9 kg per minute, preferably at or exceeding 27 kg per minute and ideally at or exceeding 36 kg per minute; and ii) capable of being stamped at a rate exceeding 100 bars per minute, preferably exceeding 300 bars per minute and ideally at a rate at or above 400 bars per minute.

Furthermore, personal washing bars produced from these compositions at high production rates should possess a range of physical properties that make them entirely suitable for every day use by mass market consumers.

Test method useful in assessing various physical properties of bars manufactured from these compositions as to establish criteria for manufacturing capability and consumer acceptability are described below in the TEST METHODOLOGY section.

BAR COMPOSITION

Fatty acid soap The fatty acid soaps, other surfactants and in fact all the components of the bar should be suitable for routine contact with human skin and preferably yield bars that are high lathering.

The preferred type of surfactant is fatty acid soap. The term "soap" is used herein in its popular sense, i.e., the alkali metal or alkanol ammonium salts of aliphatic, alkane- 25, or alkene monocarboxylic acids. Sodium, potassium, magnesium, mono-, di-and tn-ethanol ammonium cations, or combinations thereof, are the most suitable for purposes of this invention. In general, sodium soaps are used in the compositions of this invention, but from about 1% to about 25% of the soap may be potassium, magnesium or triethanolamine soaps. The soaps useful herein are the 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 of saturated or unsaturated hydrocarbons 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. Those soaps having the fatty acid distribution of peanut or rapeseed oil, or their hydrogenated derivatives, may provide the upper end of the broad molecular weight range.

It is preferred to use soaps having the fatty acid distribution of coconut oil or tallow, or mixtures thereof, since these are among the more readily available fats. The proportion of fatty acids having at least 12 carbon atoms in coconut oil soap is about 85%. This proportion will be greater when mixtures of coconut oil and fats such as tallow, palm oil, or non-tropical nut oils or fats are used, wherein the principle chain lengths are Cl 6 and higher. Preferred soap for use in the compositions of this invention has at least about 85% fatty acids having about 12 to 18 carbon atoms.

Coconut oil employed for the soap may be substituted in whole or in part by other "high-lauric" or "lauric rich" oils, that is, oils or fats wherein at least 50% of the total fatty acids are composed of lauric or myristic acids and mixtures thereof. These oils are generally exemplified by the tropical nut oils of the coconut oil class. 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.

A preferred soap is a mixture of about 10% to about 40% derived from coconut oil, palm kernel oil or other lauric rich oils ("lauric-rich soaps") and about 90% to about 60% tallow, palm oil or other stearic rich oils ("stearic-rich soaps").

The soaps may contain unsaturation in accordance with commercially acceptable standards. Excessive unsaturation is normally avoided because of the potential for rancidity.

Soaps may be made by the classic kettle boiling process or modern continuous soap manufacturing processes wherein natural fats and oils such as tallow, palm oil or coconut oil or their equivalents are saponified with an alkali metal hydroxide using procedures well known to those skilled in the art. Two broad processes are of particular commercial importance. The SAGE process where triglycerides are saponified with a base, e.g., sodium hydroxide and the reaction products extensively treated and the glycerin component extracted and recovered. The second process is the SWING process where the saponification product is directly used with less exhaustive treatment and the glycerin from the triglyceride is not separated but rather included in the finished soap noodles and/or bars.

Alternatively, the soaps may be made by neutralizing fatty acids, such as lauric (C12), myristic (C14), palmitic (C16), or stearic (C18) acids with an alkali metal hydroxide or carbonate.

The level of fatty acid soap in the bar (generally a mixture of different chainlengths and/or isomers) can range from 40% to 60%, preferably 45% to 60%, more preferably 45% to 55% and most preferably 45% to 52% based on the total weight of the bar composition.

Surfactants other than soap (commonly known as "synthetic surfactants" or "syndets") can optionally be included in the bar at levels up to about 25%, preferably up to 15%, more preferably 2% to 10% and most preferably 2% to 7% by weight of the bar.

Examples of suitable syndets are described below under OPTIONAL INGREDIENTS.

Added soluble salts By the term "added" soluble salt is meant one or more salts that are introduced in the bar in addition to the salts which are present in the bar 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.

A variety of water soluble salts could potentially be used. The preferred salts are water soluble salts that do not contain cations which precipitate with soap, i.e., which form insoluble precipitates with fatty acid carboxylates. Thus, water soluble salts containing divalent ions such as calcium, magnesium and zinc and trivalent ions such as aluminum should be avoided. Of course highly insoluble calcium salts such as calcium carbonate may be used as optional insoluble particles as part of the structuring system (see below) Especially preferred soluble salts comprise monovalent cations that form soluble fatty acid soaps (such as sodium, potassium, alkylanolammonium but not lithium) and divalent anions (e.g., sulfates, carbonates, and isethionates), trivalent anions (e.g., citrates, sulfosuccinates, phosphates) and multivalent anions (e.g., polyphosphates and polyacylates).

Especially preferred salts are sodium and potassium sulfates, carbonates, phosphates, citrates, sulfosuccinates and isethionates and mixtures thereof.

Without wishing to be bound by theory, it is believed that a limited amount of the one or more water soluble salts reduces the level of liquid crystal phase (e.g., lamellar phase) in the bar and therefore allow the bar to accommodate a composite structuring system that itself comprises some liquid. However, the incorporation of too much salt reduces the liquid crystal phase to a level where the bar becomes insufficiently pliable and exhibits excessive cracking.

The level of salt should be at least about 0.3% but less than 1.50%, preferably 0.3% to less than 1.50%, more preferably 0.3% to 0.80%.

It should be noted that the role of salts in the current invention is not primarily a lowering of water activity so as to accommodate very high levels of water in the bar which are characteristic of low TFM bars described in the prior art, i.e. the use of electrolytes to prevent or slow the drying out of the bar. In fact, the bars of the current invention have water levels that are not especially high (up to about 20%) compared with normal commercial soap bars which can range from about 13 to about 15-18%.

Thus, levels of salts in the range of 2.5 to 8% typical of the high water content bars of the prior art would be detrimental to the bars described herein.

Fatty acid A useful optional ingredient is fatty acid. Although it is well known that fatty acids are useful in improving lather, their primary function in bars described herein is modify rheology at low levels incorporated in the bar composition so as to provide adequate thermo-plasticity to the mass.

Potentially suitable fatty acids are C8-C22 fatty acids. Preferred fatty acids are C12-C18, preferably predominantly saturated, straight-chain fatty acids. However, some unsaturated fatty acids can also be employed. Of course the free fatty acids can be mixtures of shorter chainlength (e.g., C1o-C14) and longer chainlength (e.g., C16-C18) chain fatty acids. For example, one useful fatty acid is fatty acid derived from high-lauric triglycerides such as coconut oil, palm kernel oil, and babasu oil.

The fatty acid can be incorporated directly or they can be generated in-situ by the addition of a protic acid to the soap during processing. Examples of suitable protic acids include: mineral acids such as hydrochloric acid and sulfuric acid, adipic acid, citric acid, glycolic acid, acetic acid, formic acid, fumaric acid, lactic acid, malic acid, maleic acid, succinic acid, tartaric acid and polyacrylic acid.

The level of fatty acid should not exceed 5.0%, preferably not exceed about I % and most preferably be between 0.3% and 0.8% based on the total weight of the bar composition.

Structuring system The structuring system includes one or more starch components, one or more polyols and optionally, water insoluble particles (i.e., particulate material).

The total level of the structuring system used in the bar composition should be at least about 20% but no more than 30.0%, preferably from 25% to 30.0% based on the total weight of the bar composition. By total level of the structuring system is meant the sum of the weights of the starch, polyol, and optional insoluble particle components.

Suitable starch materials include natural starch (from corn, wheat, rice, potato, tapioca and the like), pregelatinzed starch, various physically and chemically modified starch and mixtures thereof. by the term natural starch is meant starch which has not been subjected to chemical or physical modification -also known as raw or native starch.

A preferred starch is natural or native starch from maize (corn), cassava, wheat, potato, rice and other natural sources of it. Raw starch with different ratio of amylose and amylopectin: e.g. maize (25% amylose); waxy maize (0%); high amylose maize (70%); potato (23%); rice (16%); sago (27%); cassava (18%); wheat (30%) and others.

The raw starch can be used directly or modified during the process of making the bar composition such that the starch becomes gelatinized, either partially or fully gelatinized.

Another suitable starch is pre-gelatinized which is starch that has been gelatinized before it is added as an ingredient in the present bar compositions. Various forms are available that will gel at different temperatures, e.g., cold water dispersible starch. One suitable commercial pre-gelatinized 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.

The amount of the starch component in the filler can range from about 5% to about 25%, preferably 6% to 25%, preferably 10% to 25%, preferably 10% to 20%, and preferably 10% to 15% by weight of total bar composition.

A second critical component of the structuring system is a polyol or mixture of polyols. Polyol is a term used herein to designate a compound having multiple hydroxyl groups (at least two, preferably at least three) which is highly water soluble, preferably freely soluble, in water.

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

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 polyol are glycerol, sorbitol and their mixtures.

The level of polyol is critical in forming a thermoplastic mass whose material properties are suitable for both high speed manufacture (300-400 bars per minute) and for use as a personal washing bar. It has been found that when the polyol level is too low, the mass is not sufficiently plastic at the extrusion temperature (e.g., 40°C to 45° C) and the bars tend to exhibit higher mushing and rates of wear. Conversely, when the polyol level is too high, the mass becomes too soft to be formed into bars by high speed at normal process temperature.

The level of polyol should be between 5.0% and 14.0%, preferably 6 to 12% and preferably about 6% to about 10% by weight based on the total weight of the bar composition. Furthermore, it has been found that the ratio of polyol to starch be preferably between about 1:1 to 1:4.5 byweight, and more preferably between 1:1 and 1:1.25.

The structuring 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. The particulate material can potentially be inorganic or organic or a combination as long as it is insoluble in water.

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 mircons and most preferably less than 50 microns.

Preferred inorganic particulate material include 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.

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 known as 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 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.

The structuring system can comprise up to 10% insoluble particles, preferably 5% to 8%, based on the total weight of the bar composition.

Water content As already mentioned the bar compositions of the invention do not comprise an especially high level of water compared to typical extruded and stamped soap bars which typically can range from about 13 to about 18% water when freshly made, i.e., after extrusion and stamping. In fact, it is preferable that the water content of the freshly made bar should be less than 20% and preferably be between 14% and 18% based on the total weight of the bar. Thus, in preferred embodiments, the water level of the freshly made bars of the invention is lower than the water content of freshly made melt and pour or melt-cast bars, i.e., the nominal water content based on the formulation, which typically exceeds 25% by weight in melt-cast compositions.

It is stressed that the preferred water levels quoted above refers to freshly made bars. As is well known, soap bars are subject to drying out, i.e., water evaporation.

Hence depending upon how the bar is stored (type of wrapper, temperature, humidity, air circulation, etc) the actual water content of the bar at the moment of sampling can obviously differ significantly from the initial water content of the bar immediately after manufacture.

Optional ingredients Synthetic surfactants: 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 present in the bar is generally less than 25%, preferably less than 15%, preferably up to 10%, and most preferably from 0 to 7% based on the total weight of the bar composition.

The anionic surfactant may be, for example, an aliphatic sulfonate, such as a primary alkane (e.g., C8-C22) sulfonate, primary alkane (e.g., C8-C22) disulfonate, C8-C22 alkene sulfonate, C8-C22 hydroxyalkane sulfonate or alkyl glyceryl ether sulfonate (AGS); or an aromatic sulfonate such as alkyl benzene sulfonate. Alpha olefin sulfonates are another suitable anionic surfactant.

The anionic may also be an alkyl sulfate (e.g., C12-C18 alkyl sulfate), especially a primary alcohol sulfate or an alkyl ether sulfate (including alkyl glyceryl ether sulfates).

The anionic surfactant can also be a sulfonated fatty acid such as alpha sulfonated tallow fatty acid, a sulfonated fatty acid ester such as alpha sulfonated methyl tallowate or mixtures thereof.

The anionic surfactant may also be alkyl sulfosuccinates (including mono-and dialkyl, e.g., C6-C22 sulfosuccinates); alkyl and acyl taurates, alkyl and acyl sarcosinates, sulfoacetates, C8-C22 alkyl phosphates and phosphates, alkyl phosphate esters and alkoxyl alkyl phosphate esters, acyl lactates or lactylates, C8-C22 monoalkyl succinates and maleates, sulphoacetates, and acyl isethionates.

Another class of anionics is C8 to C20 alkyl ethoxy (1-20 EO) carboxylates.

Another suitable anionic surfactant is C8-C18 acyl isethionates. These esters are prepared by reaction between alkali metal isethionate with mixed aliphatic fatty acids

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having from 6 to 18 carbon atoms and an iodine value of less than 20. At least 75% of the mixed fatty acids have from 12 to 18 carbon atoms and up to 25% have from 6 to 10 carbon atoms. The acyl isethionate may also be alkoxylated isethionates Acyl isethionates, when present, will generally range from about 05% to about 25% by weight of the total composition.

In general, the anionic component will comprise the majority of the synthetic surfactants used in the bar composition.

Amphoteric detergents which may be used in this invention include at least one acid group. This may be a carboxylic or a sulphonic acid group. They include quaternary nitrogen and therefore are quaternary amido acids. They should generally include an alkyl or alkenyl group of 7 to 18 carbon atoms. Suitable amphoteric surfactants include amphoacetates, alkyl and alkyl amido betaines, and alkyl and alkyl amido sulphobetaines.

Amphoacetates and diamphoacetates are also intended to be covered in possible zwitterionic and/or amphoteric compounds which may be used.

Suitable nonionic surfactants include the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols or fatty acids, with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Examples include the condensation products of aliphatic (C8-C18) primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

The nonionic may also be a sugar amide, such as alkyl polysaccharides and alkyl polysaccharide amides.

Examples of cationic detergents are the quaternary ammonium compounds such as alkyldimethylammonium halides.

Other surfactants which may be used are described in U.S. Pat. No. 3, 723,325 to Parran Jr. and "Surface Active Agents and Detergents" (Vol. I & II) by Schwartz, Perry & Berch, both of which is also incorporated into the subject application by reference.

Slip Modifier: Very useful optional ingredients are slip modifiers. 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 at a level of I % or less, preferably from 0.05 to I % and more preferably from 0.05% to 0.5%.

Slip modifiers are particularly useful in bar compositions which contain starch and/or insoluble particles whose levels approach the higher end of the useful concentration range for these materials, e.g., 20 -25% for starch. 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, other dislike it. In general, consumers prefer bars that are perceived to glide easily over their skin and are perceived as being slippery.

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

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

Particularly suitable slip modifier are high molecular weight polyethylene oxide resins because they have been found to be effective at relatively low concentrations in the composition. 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 POLYOX. An example is WSR N-301 (molecular weight 4,000,000 Daltons).

Adjuvants: 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 the bar composition of the 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 XLI000), parabens, sorbic acid and the like; anti-oxidants such as, for example, butylated hydroxytoluene (BHT); chelating agents such as salts of ethylene diamine tetra acetic acid (EDTA) and trisodium etridronate; emulsion stabilizers; auxiliary thickeners; buffering agents; and mixtures thereof.

The level of pearlizing agent 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 bar composition.

Skin benefit agents: 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; other types of 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 D 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-dandruf agents such as zinc pyridinethione; hair growth promoters such as finasteride, minoxidil, vitamin D analogues and retinoic acid and mixtures thereof.

MATERIAL PROPERTIES OF AN EXTRUDED MASS

The personal washing bars described herein are extruded masses. By the term "extruded masses" is meant that the bars are made by a process which involves both the intensive mixing or working of the soap mass while it is in a semi-solid plastic state and its forming into a cohesive mass by the process of extrusion.

The intensive mixing can be accomplished by one or more unit operations known in the art which can include roller milling, refining, and single or multistage extrusion.

Such processes work the bar mass, e.g., soap mass, at a temperature between about 3Q0 C and about 5Q0 C to form a homogeneous network of insoluble materials in a viscous liquid and/or liquid crystalline phase containing the lower melting, more soluble surfactants (e.g., soaps and other water soluble/dispersible materials).

An extruded mass must be thermoplastic within the process temperature of extrusion which is generally between about 30°C and about 45°C, preferably at a temperature between about 33°C to about 42°C. Thus, the material must soften within this process temperature window but remain highly viscous, i.e., not softer excessively to form a sticky mass. The material must regain its structure and harden quickly as the temperature is lowered below its softening point. This means that the internal structure must reform quickly generally by re-solidification of structure forming units, e.g., crystals.

Furthermore, the softened mass although pliable must be sufficiently viscous so that is does not stick to the surfaces of the extruder in order to be capable of conveyance by the extruder screws but not bend excessively when exiting the extruder as a billet. However, if the mass is too viscous it will not be capable of extrusion at reasonable rates. Thus, the hardness of the mass should fall within limits within the process temperature window to be capable of high rates of production. By high rate of production is meant in excess of about 50 tablet or bars per minute (4.5 Kg/mm for a 90 Kg bar), preferably greater than about 150 bars per minute (13.5 Kg/mm), more preferably greater than 250 bars per minute (22.5 Kg/mm) and still more preferably greater that 400 bars per minute (36 Kg/mm).

Personal washing bars formed by extrusion (also commonly known as milled soaps) have physical-chemical properties and an internal structure which are quite different from soaps that are made by a melt-cast process wherein the bar composition is first melted at high temperature (e.g., 7Q0 C) to form a liquid phase which is then poured into molds to solidify by quiescent cooling.

These differences in internal structure, composition and physical-chemical characteristics provide extruded personal washing bars with overall in-use properties which are better suited for the mass market than cast soaps. These properties include: much lower wear rates, more resistance to scuffing and denting, and a richer, more creamy opaque lather.

The one or more key properties that serve as characteristic "finger-prints" of an extruded mass are structural anisotropy, the level of high melting point materials such as stearic soaps, high melting point and thermal reversibility, and rapid recovery of hardness after heating and shear. These characteristics are briefly described below.

Structural anisotropy Bars made by extrusion typically have a characteristic anisotropic internal structure both with respect to the alignment of crystals and overall macro-structure.

One important element of the macro-structure is the "candle structure", disclosed for example by Schonig et al in US patent 4,720,365 which is produced in the plodder and modified in the stamper. Shear forces generated at the eyeplate and subsequent extensional forces in the plodder cone produce marked alignment within the candles and thus influence the colloidal structure of the extruded mass. Although there is some modification of alignment after stamping, the resultant bar usually has a characteristic macroscopic alignment of the crystallites and domains relative to the bar surface and some residual candle structure.

The liquid (crystalline) phase generated at the extrusion temperature has a relatively lower viscosity and is expected to preferentially flow to the surface of the candles during the plodder compression stage.

In contrast, melt-cast bars have a predominantly isotropic structure because crystallization occurs during quiescent cooling and thus the alignment of crystals is minimal and there is no candle structure.

The differences in internal structure between extruded and melt-cast bars can be visualized by a simple ethanol extraction procedure. In this procedure bars are shaven, for example with a plane of mandolin to reveal inside surfaces (the bars can be shaved in several orthogonal directions). These shaved sections are then immersed overnight in anhydrous alcohol. After removal from the alcohol, the bars are allowed to dry by standing a pattern of small cracks appears. These cracks are indicative of the orientated micro-structure of the bar. The alcohol extracts the more soluble soaps in extruded bars, thus exposing the candle structure interface and the lines of flow. In melt-cast bars flow lines and the candle structure are absent and fine cracks are much less pronounced or absent after alcohol emersion.

Level of high melting materials In order to achieve the rheological properties required for milling and extrusion, an extruded mass must have a sufficient level of solid particles to adequately structure the mass at the process temperature, i.e., the bar contains materials whose melting point is above the extrusion temperature.

For bars that are comprised predominantly of soap, these high melting solids are provided in at least part by the stearic soaps which include the C16 and C18 saturated soaps.

The level of high melting solids (melting point greater than the extrusion temperature) found in extruded bars is generally greater than 20%, and typically greater than 30%. For an extruded suitable for the instant invention which are predominantly comprised of soaps, the level of stearic-rich soaps is generally between about 25% and about 55% based on the total weight of bar, preferably between 25% to about 40%.

Other sources of solid particles are also present in the bars described herein.

Melting point and thermal reversibility Because of the presence of significant high melting solids (e.g. steric-rich soaps and structurants) and the lower levels of liquids relative to cast soaps, extruded masses have melting points that are generally above 80° C, typically above 90° C and usually above 100°C. In contrast, cast soaps generally melt at temperature between 70°C and 80° C. Furthermore an extruded mass regains its structure and harden quickly as the temperature is lowered below its softening point. This means that the internal structure reform quickly, generally by re-solidification of structure forming units, e.g., soap crystals. This rapid re-solidification is generally observed as thermal reversibility in differential scanning calorimetry (DSC). By the term thermal reversibility is meant that increasing and decreasing temperature sweeps tend to be superimposible albeit offset by a temperature difference characteristic of the composition. In contrast, cast soaps require much longer periods of time to reform the solid structural units and exhibit lower thermal reversibility, e.g., increasing-decreasing temperature sweeps are either not super-imposable or are offset by much larger temperatures than is found with an mass.

Recovery of hardness after heating and shear An extruded mass must soften when it is heated to the extrusion process temperature which is typically in the range of about 35° C to about 45° C. However, at this temperature it must retain sufficient hardness. It has been found experimentally that to achieve the desired rates of production, the hardness of the mass should generally be at least about 1500 g, preferably at least 3000g but generally not greater than about 8000 g, preferably between 3000g and 5000g when measured by the Hardness Penetration Test described in the TEST METHODOLOGY section, said measurement being carried out at a temperature in the range of about 40° C. An extruded mass also remains cohesive after its has been subjected to sheer at the extrusion temperature without exhibiting excessive pliability or stickiness. By the term "remain cohesive" is meant when compacted under pressure the mass should be capable of sintering together to form a single cohesive unit that has mechanical integrity.

Finally, it has been found that an extruded mass quickly recovers its yield stress (as measured by its penetrometer hardness) when it is subjected to shear at the extrusion temperature (e.g., 40° C) and allowed to cool. For example when the extrudate is cooled after extrusion to 25°C, the mass should recover at least about 75%, preferably at least about 85% and more preferably at least about 95% of the initial hardness before it was sheared, by for example, extrusion through an "orifice" extruder -see below.

The influence of shear on cohesivity, stickiness, pliability and recovery of yield stress can be assessed utilizing an "orifice" extruder which provides a controlled extensional flow similar to that encountered by the mass during extrusion through an eye plate. This device comprises a thermal jacketed barrel (e.g. 350 mm length by 90 mm in diameter) ending in a narrow opening (typically 2-4 mm) and a plunger which is coupled to a drive unit e.g., Instron Mechanical Tester. The plunger forces the mass through the orifice to form an extrudate. The extrudate can be assessed at the process temperature.

The extrudate can be placed in the barrel of the orifice extruder, compressed under different loads and removed to determine its cohesivity or extent of cohesion, its stickiness and its ability to recover its hardness after it has been sheared at the extrusion temperature (e.g., 40° C) and cooled (e.g., 25° C).

Based on the above extrudability criteria, so called melt and pour compositions such as those used to make glycerin soaps that require casting in molds in order to form bars are not extrudable masses when they are initially formed from the melt and are not suitable. Thus, after a cast melt composition is melted and allowed to solidify in a mold for several hours, the composition does not form a cohesive non-sticky mass after extrusion through an orifice extruder and the extrudate does not exhibit the required recovery of hardness after cooling.

In addition to the requirement of being suitable for extrusion, the bar mass should also be sufficiently hard to be stamped with conventional soap making dies. The stamping process involves placing a billet or ingot of the extruded mass into a split mold comprised of generally two moveable halves (the dies). These dies when closed compress the billet ("stamp" the billet), squeezing out excess mass and defining the ultimate shape of the bar. The mold halves meet at a parting line which becomes visible as a line on the edge perimeter of the molded finished bar (stamped bar). Thus, a stamped personal washing bar can be characterized as comprising top and bottom stamped faces meeting at a parting line.

Experience has shown that stamping can be achieved by ensuring that an extruded billet of the bar mass (also known as an ingot) has a minimum hardness of at least about 1500 g at the stamping temperature which is typically in the range 25° to 45° C. The one or more key characteristics of an extruded mass are summarized in the

table below.

CHARACTERISTIC EXTRUDED MASS CAST SOAP

PROPERTY

Structural anisotropy Aligned crystals generally random crystal Distinct flow lines/candle orientation structure evident as small Absence of candle structure cracks formed after alcohol No prominent and systematic emersion lines or cracks evident after alcohol emersion Levels of stearic-rich 20% to about 55% based on Generally less than 15% or soaps (C16/C18 soaps) the total weight of bar absent Melting point/Thermal Melting point above 80° C, Melting point 70° C and characteristics typically above 90° C and 80°C.

usually above 100° C. Relatively high degree of Relatively low degree of thermal reversibility (DSC) thermal reversibility Recovery of hardness Recovers at least about After melting and casting after heating and shear 75%, preferably at least ether low recovery of about 85% and more hardness after shear and/or preferably at least about lack of formation of cohesive 95% of its initial hardness mass after shear (excessive before shearing, fracture or softening) Forms cohesive mass after extensional shear (Orifice extrud er)

TEST METHODOLOGY

Bar Hardness -Penetrometer Hardness Test A variety of methods are known in the art to measure the hardness of soft solids such as toilet soaps. The techniques used in the current work, is the Penetration Test which measures the penetration of a needle or tapered rod under load. The distance traveled (penetration of the needle into the test mass) under a constant load or the load required to produce a given distance of penetration can be measured. In the test method used in the present work, the latter measurement approach is employed, i.e., variable load to achieve fixed penetration depth.

Although the invention is described by parameters that are measured by the Penetration Test, various hardness tests can be used and inter-correlated with the methods used herein.

Hardness penetration measurements were made using finished toilet soap bars using the TA-XT Plus Texture Analyzer supplier by Stable Micro Systems.

The rheological parameters of the finished bars were determined by measuring the weight necessary for the test probe to penetrate the sample to a distance of 15 mm (see table below). The 3Q0 conical test probe is made from X2 stainless steel and the dimensions are: Length, 60.4 mm; Diameter 30 mm.

The instrument parameters used in hardness analyses with TA-XT Express are given in the table below Parameters Value Load cell capacity (kg) 10 Pre-speed (mm/s) 2 Return speed (mm/s) 10 Conical Probe Angle (°) 30 Trigger Force (g) 5 Test speed (mm/s) I Distance of penetration (mm) 15 The TA-XT Plus Texture Analyser allows for various preset probe speeds. In the examples described herein, the rheological parameters other then hardness were carried out at various speeds (minimum 10), ranging from 0.01 to 10 mm/sec and the forces measured accordingly. Shear stresses and shear rates were calculated and rheological charts were built. The rheological parameters were finally calculated by least-squares utilizing the Herschel-Bulkley equation: where a is the shear stress, a0 is the yield stress, k stands for the consistency index, n is the flow index and y is the shear rate.

Stickiness was measured using the TA-XT Plus Texture Meter using the compression mode and by acquiring the peak reading when a 45° conical probe left the sample. The other parameters were: penetration distance 10mm, pre-test speed (10 mm.s1), test speed (lmm.s1), and post-test speed (10 mm.s1).

Wear Rate Test The wear rate of the bar was measured by the following procedure.

Four weighed samples of each test bar are placed on soap trays. Two types of soap trays are employed: those that have drainers or raised grids so the water left on the bar after rinsing is drained away; and no drainers so that water can be added to the tray to allow the bars to become "water-logged". The trays are coded as follows: With drainers? Wash temperature (°C) Yes 25 Yes 40 No 25 No 40 ml of distilled water (ambient temperature) are poured into the undrained tray (25° and 40° C).

Each tablet of soap as follows: -Fill washing bowl with about 5 litres of water, at the desired temperature (20°C or 40°C).

-Mark the tablet to identify top face (e.g. make small hole with a needle).

-Wearing waterproof gloves, immerse the tablet in the water, and twist 15 times (180° each time) in the hands above water.

-Repeat the above step -Briefly immerse tablet in the water to remove lather.

-Place tablet back on its soap tray, ensuring that the opposite face is uppermost (i.e. the unmarked face).

The above procedure is carried out 6 times per day for 4 consecutive days, at evenly spaced intervals during each day. Alternate face of each bar is placed in the down downward position (facing the bottom of the tray) after each washdown. Between washdowns the soap trays should be left on an open bench or draining board, in ambient conditions. After each washdown cycle, the position of each soap tray/tablet is changed to minimize variability in drying conditions.

At the end of each day each soap tray with drainer is rinsed and dried. Soap trays without drainers are refilled with 10 ml distilled water (ambient temperature). After the last washdown (4th day), all soap trays are rinsed and dried. Each washed bar is placed in its tray and allowed to dry for up to a period of 9 days. On the 5th day afternoon, the samples are turned so that both sides of the tablet dry. On the 8th day, each tablet is weighed.

The rate of wear is defined as the percent weight loss as follows: %Wear = (initial weight -final weight) *100 initial weight Bar Mush Test Mush is a paste or gel of soap and water, formed when soap is left in contact with water as in a soap-dish. Soluble components of the soap move into solution, and water is absorbed into the remaining solid soap causing swelling, and for most soaps, also recrystallization. The nature of the mush depends on the balance of these solution and absorption actions. The presence of a high level of mush is undesirable not only because it imparts an unpleasant feel and appearance to the soap, but also especially because the mush may separate from the bar and leaves a mess on the wash basin. Residual mush or soap residue is a known consumer negative.

The Mush Immersion Test described herein gives a numerical value for the amount of mush formed on a bar. The test is carried out as follows: A rectangular billet from the soap tablet is cut to the required dimensions using a plane, knife or cutting jig. The width and depth of the cut billet are accurately measured ( +1-0.1 cm). A line is drawn across the billet 5 cm from the bottom of the billet. This line represents the immersion depth.

The billet is attached to a sample holder and suspend in an empty beaker.

Demineralised (or distilled) water at 20°C is added to the beaker until the water level reaches the 5 cm mark on the billet. The beaker is placed in a water bath at 20°C (+1- 0.5°C) and left for exactly 2 hours.

The soap-holder + billet is removed, the water emptied from the beaker, and the soap-holder + billet is replaced on the beaker for 1 minute so that excess water can drain off. Extraneous water is shaken off, the billet is removed from the soap-holder, and the weight of the billet standing it on its dry end is recorded (WM).

All the mush from all 5 faces of the billet is carefully scraped off, and any remaining traces of mush are removed by wiping gently with a tissue. The weight of the billet within 5 minutes of scraping is recorded (WR).

The quantitative amount of mush is calculated as follows: Mush(g/50cm2)=WMWrx5O where A is the surface area: Surface area (cm2) = A = 10 (width + thickness) + (width x thickness) Accelerated Bar Cracking Test The potential of bars to crack in use is assessed by washing the bars in a controlled manner 6 times per day for 4 days, storing the bars between washes under different conditions to simulate different consumer habits and then allowing the bars to dry for different periods of time to induce cracking. The procedure is as follows: Four weighed of each test bar are placed on soap trays. Two types of soap trays are employed: those that have drainers or raised grids so the water left on the bar after rinsing is drained away; and no drainers so that water can be added to the tray to allow the bars to become "water-logged". The trays are coded as follows: With drainers? Wash temperature (°C) Yes 25 Yes 40 No 25 No 40 ml of distilled water (ambient temperature) are poured into the undrained tray (25° and 40°C).

Each tablet of soap as follows: -Fill washing bowl with about 5 litres of water, at the desired temperature (20°C or 40°C).

-Mark the tablet to identify top face (e.g. make small hole with a needle).

-Wearing waterproof gloves, immerse the tablet in the water, and twist 15 times (180° each time) in the hands above water.

-Repeat the above step -Briefly immerse tablet in the water to remove lather.

-Place tablet back on its soap tray, ensuring that the opposite face is uppermost (i.e. the unmarked face).

The above procedure is carried out 6 times per day for 4 consecutive days, at evenly spaced intervals during each day. Alternate face of each bar is placed in the down downward position (facing the bottom of the tray) after each washdown. Between washdowns the soap trays should be left on an open bench or draining board, in ambient conditions. After each washdown cycle, the position of each soap tray I tablet in changed to minimize variability in drying conditions.

At the end of each day each soap tray with drainer is rinsed and dried. Soap trays without drainers are refilled with 10 ml distilled water (ambient temperature). After the last washdown (4th day), all soap trays are rinsed and dried and place each washed bar is placed in its tray and allows to dry for up to a period of 9 days.

A subjective assessment of the degree of cracking is carried out on each bar.

Some cracking may occur during the first 5 days of the test, but for maximum sensitivity and realism it is best to assess the cracking after drying out (i.e. on the 8th or 9th day).

A trained assessor examines the tablets and records separately the degree of cracking in each of the following areas: Both faces -all types of tablets; both ends -band-type tablets; both sides -band-type tablets periphery -capacity die tablets The degree of cracking is graded using the following 0-5 scale: 0 -No cracking I -Small and shallow cracking: 2 -Small and medium deep cracking: 3 -Medium and deep cracking: 4 -Big and deep cracking: 5 -Very big and very deep cracking: It is advantageous to use photographic standards representing each of these grades, produced from typical local soap samples. This gives greater consistency of assessment between technicians.

EXAMPLES

The following non-limiting examples illustrate various aspects of the invention and preferred embodiments. Examples of the invention are designated with the prefix "E" while comparative examples are designated with the prefix "C".

Examples 1-6

These examples illustrates exemplary bar compositions according to the invention.

The compositions used to prepare the personal washing bars of examples E1-E6 are shown in Table 1. The bars were prepared using conventional equipment used in the manufacture of extruded soap. In summary, the composition was prepared by combining soap noodles with the remaining ingredients in Table I in a Z-blade mixer and passing the mixture through a 3-roll mill and a refiner. The soap noodles were composed of a mixture of lauric-rich and stearic-rich soaps used in a weight ratio in the range from 40/60 to 10/90. The lauric-rich soaps were derived from palm kernel oil, coconut oil and/or babasu oil. The stearic-rich soaps were derived from tallow, palm oil, palm stearine, hardened soybean oil and crude soybean oil. The compositions so processed were added to the hopper of a two stage extruder and extruded at a temperature of 35°C at an extrusion rate of 1.2 -4.0 kg/mm through an eyeplate having a 3.5 X 3.5 cm cross section to form billets cut to about 12 cm in lengths. The billets were then transferred to a manual soap stamper and stamped to form the finished personal washing bar utilizing a die set defining a mold having a volume of approximately 79 to 80 cm3 (density in the range from 1.12 to 1.14 g/cm3).

The physical and overall user properties are included in the table. The second column from the left under physical properties provides the "ideal range" for these properties to achieve a bar that combines excellent manufacturability and overall user properties. All the exemplary compositions provided reduced TFM bars which could be processed at high rates (e.g., 300 bars per minute) and had acceptable in-use properties for mass market applications.

Table I. Composition and physical properties of Examples 1-6 INGREDIENTS El E2 E3 E4 E5 E6 (El) (E2) (E3) (E4) (E5) (E12) Wt% based on total bar composition Fat Charge Vegetable (PO/POS/PKO or 40/40/20 -50/30/ 30/50/ -40/40/ PO/POS/CNO) See note A 20 20 20 Fat Charge Non-vegetable (TLW/SBO/PKO -72/8/ --75/5/ -or TLW/SBO/CNO) See note B 20 20 Anhydrous soap (see below) 55.2 55.2 54.2 52.2 53.2 52.2 Synthetic detergent ---3 -3 Glycerin 10 10 10 10 6 14 Native starch 10 15 10 5 18 6 Talc 5 -5 Calcium carbonate --5 Sodium sulfate 0.5 0.5 0.5 0.5 0.5 0.5 Fatty acid 0.5 0.5 0.5 0.5 0.5 0.5 Perfume 1.3 1.3 1.3 1.3 1.3 1.3 Minors (preservatives, NaCI, dyes and 1.5 1.5 1.5 1.5 1.5 1.5 pigments, impurities) _________ _______ ______ ________ ______ ______ Water 16 16 17 16 19 16 PHYSICAL PROPERTIES Ideal Range Hardness �40°C (kg) 3.0-5.0 4.9 4.6 5.0 4.2 4.1 4.6 Yield stress �40°C (kPa) 350 851 851 900 700 630 640 Extrusion Throughput High High High High High High High Bar Slip Subjective (note C) Slippery (5) 5 5 5 S SD S Cracking level (0-5) 0-1 0-1 0-1 0-1 0-1 0-1 0-1 Rate of wear (%) <35 29 30 35 33 29 33 Mush Objective(g/50cm2) <16 17 15 16 15 14 14 Mush Subjective Low-Medium L-M L M L L L Abbreviations Note A: P0 stand for Palm Oil, POS stands for Palm Oil Stearine, PKO stands for Palm Kern Oil, CNO stands for Coconut Oil, TLW stands for Tallow and SBO stand for Soybean Oil.

Note B: Slippery (5), Slightly Draggy (SD), Draggy (D), All the samples were manufactured using SWING soap noodles IV 39, which means SWING vegetable soap noodles made with PO/POS/PKO in the fat charge ratio of 40/40/20 and SWING non-vegetable soap noodles made with tallow/Soybean oil/ PKO in the fat charge ratio of 72/8/20.

Other levels of PKO could be used.

Comparative Examples 1-8 These comparative examples illustrates the criticality of the levels of polyol, starch and inorganic particulate material employed in the bar composition.

The compositions of comparative examples Cl -C8 are given in Table 2. The compositions were prepared and processed into bars according to the procedures described under Examples 1-6.

Although some composition could be formed into bars by extrusion at low throughputs, none of the compositions were acceptable for high speed extrusion and stamping.

Bars having greater than about 14% polyol were very soft, had a high rate of wear and produced excessive mush during use. In contrast, bars having high levels of starch without polyol or insoluble particulates without starch were brittle, were more difficult to process, exhibited a high rate of wear and were perceived to have a very draggy bar feel in use which was not well liked by consumers.

The comparative examples C1-C8 were difficult to process into bars either because the material was too soft or not sufficiently plastic. Although bars could be produced at low rates of extrusion and stamping in some cases, the bars had inferior user properties. Example C*8 was not acceptable even though the polyol and starch levels were in the range recited in Claim 1. These results demonstrate that all possible combinations within the broad ranges recited do not produce acceptable bars meeting the limitations recited in claim 1.

Table 2. Compositions of comparative example CI -C7 INGREDIENTS CI C2 C3 C4 C5 C6 C7 C*8 Wt% based on total bar composition Anhydrous soap 49.2 42.3 59.2 46.2 54.2 53.2 53.7 54.2 Synthetic detergent Glycerin 10 6 5 15 15 15 15 12 Native starch 3 30 0 10 10 10 5 10 Talc 5 0 15 5 0 0 5 0 Calcium carbonate 8 0 Sodium sulfate 1.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Fatty acid 0.5 0.5 0.5 0.5 0.5 0.5 0 0.5 Perfume 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Minors (preservatives, NaCI, dyes and 1.5 1.5 1.5 1.5 1.5 1.5 1.6 1.5 pigments, impurities) ______ _______ _______ _____ _______ _____ _____ _____ Water 20 17 17 20 18 18 18 20 PHYSICAL Ideal Range

PROPERTIES _________ _____ _____ _____ ____ _____ ____ ____ ____

Hardness �40°C (kg) 3.0-5.0 2.0 4 3.0 NP NP 2.65 2.0 2.5 Yield stress �40°C (kPa) >350 230 700 320 NP NP 300 380 390 Extrusion Throughput High V. Med Low NP NP Low Low Low Low BarSlipSubjectivea Slippery(S) S VD D NP NP S S S Cracking level (0-5) 0-1 2 2 2 NP NP 2 2 2 Rate of wear(%) <35 32 48 43 NP NP 36 37 40 Mush Objective(g/50cm2) <16 14.5 17 26 NP NP 21.4 22.0 24.8 Mush Subjective Low-H H H NP NP H H H ______________________ Medium ______ ______ ______ _____ ______ _____ _____ _____ a) Descriptors -Slippery (5), Slightly Draggy (SD), Draggy (D)

Example 7-10

These examples illustrate the advantageous use of bar slip modifiers.

The compositions of examples E7 -ElO are given in Table 3. The compositions were made according to the procedure described under examples 1-6.

Compositions E7 and E9 yielded bars that could be processed and stamped at high speeds and which had good overall user properties except in the area of bar slip.

E7 and E9 bars were perceived by a consumer panel to be "slightly draggy" and draggy respectively when used in a shower, i.e., the wet bars exhibited a higher than preferred friction when rubbed against the wet skin. Surprisingly, when very low levels of the slip modifiers (POLYOX WSR 301) were incorporated in the compositions the bar friction was reduced and the bars were perceived as slippery. Also surprising is the fact that this change in friction did not affect any of the other physical properties characteristic of the bar.

Table 3. Compositions of Examples E7 -ElO E7 E8 E9 ElO INGREDIENTS (E5) (E7) (E6) (E8) Wt% Anhydrous soap 53.2 53.05 50.2 50.0 Synthetic detergent ---Bar Slip Modifier (POLYOX WSR 301) 0 0.15 0 0.2 Glycerin 6 6 5 5 Native starch 18 18 25 25 Talc Calcium carbonate Sodium sulfate 0.5 0.5 0.5 0.5 Fatty acid 0.5 0.5 0.5 0.5 Perfume 1.3 1.3 1.3 1.3 Minors (preservatives, NaCI, dyes and 1.5 1.5 1.5 1.5 pigments, impurities) ________ __________ ________ _________ Water 19 19 16 16 PHYSICAL Ideal Range

PROPERTIES __________ ______ _______ ______ _______

Hardness �40°C (kg) 3.0-5.0 4.1 4.1 4.5 4.5 Yield stress @40° C (kPa) >350 630 630 680 680 Extrusion Throughput High H H H H Slightly Slippery Draggy Slippery Bar Slip Subjectivea Slippery Draggy Cracking level (0-5) 0-1 0-1 0-1 0-1 0-1 Rate of wear(%) <35 29 29 31 31 Mush Objective(g/50cm2) <16 14 14 13 13 Mush Subjective Low-Low Low Low Low ______________________ Medium _______ _________ _______ ________ a) Descriptors -Slippery (5), Slightly Draggy (SD), Draggy (D) Example 11-12 and Comparative Examples 9-11 These examples illustrate the criticalities of the levels of hardening electrolytes (e.g., sodium sulfate) and plasticizing fatty acid on the processability and quality of the bar.

The compositions of examples E11-E12 and comparative examples C9-C11 are given in Table 4. The compositions were prepared and processed into bars according to the procedures described under Examples 1-6.

Compositions Eli and E12 yielded the best bars in terms of high-throughput extrusion and stamping and overall user properties.

In contrast, bars made from comparative compositions C9 and ClO having 1% sodium sulfate exhibited excessive cracking while bar made from composition Cii and Ci2 having levels of 2% fatty acid (and higher) were too soft for high speed extrusion and exhibited excessive mush.

Table 4. Compositions of examples E11-E12 and comparative examples C9-C11 Eli E12 C9 ClO Cii Ci2

INGREDIENTS Wt%

Anhydrous soap 54.9 54.2 53.2 51.2 52.2 49.7 Synthetic detergent Glycerin 6 10 10 6 10 6 Native starch 14 10 10 14 10 14 Talc 5 5 5 5 5 5 Calcium carbonate Sodium sulfate 0.5 0.5 1 1 0 0.5 Fatty acid 0.8 0 0 0 2 2 Perfume 1.3 1.3 1.3 1.3 1.3 1.3 Minors (preservatives, NaCI, dyes and 1.5 1.5 1.5 1.5 1.5 1.5 pigments, impurities) _______ _______ _______ _______ _______ _______ Water 16 16.6 18 20 10 20 PHYSICAL Ideal PROPERTIES Value _____ _____ _____ _____ _____ _____ Hardness �40°C (kg) 3.0-5.0 4.7 6.3 5.8 4.7 4.7 4.6 Yield stress �40°C (kPa) >350 710 1100 610 740 740 1000 Extrusion Throughput High High High High Low Low High Bar Slip Subjectivea Slippery S S S S S S ___________________ (5) _____ _____ _____ _____ _____ _____ Cracking level (0-5) 0-1 0 4 5 3 3 4 Rate of wear (%) <35 30 26 32 25 25 38 Mush Objective(g/50cm2) <16 14 14 10 16 16 17 Mush Subjective Low-Low Low Low High High High ______________________ Medium ______ ______ ______ ______ ______ ______ a) Descriptors -Slippery (5), Slightly Draggy (SD), Draggy (D)

Example 13-18

These examples illustrate the influence of polyol to starch ratio.

The compositions of examples E13 -E18 are given in Table 5. The compositions were prepared and processed into bars according to the procedures described under Examples 1-6.

Although all the compositions could be formed into bars at high rates production, compositions E18 yielded a bar that was excessively draggy and was less preferred by consumers. It is preferable to maintain the polyol to starch ratio below 1:4, more preferably below 1:3, more preferably between 1:1 and 1:2.5.

Table 5. Compositions of examples E12-E15 and comparative examples C16 INGREDIENTS E13 E14 E15 E16 E17 E18 Anhydrous soap 55.2 54.9 53.2 56.4 49.7 53.9 Synthetic detergent Glycerin 10 6 6 7.6 6 6 Native starch 10 14 18 13 17.5 24 Talc 5 5 2 5 Calcium carbonate Sodium sulfate 0.5 0.5 0.5 0.5 0.5 0.5 Fatty acid 0.5 0.8 0.5 0.5 0.5 0.5 Polyol/Starch Ratio 1:1 1:2.3 1:3 1:1.7 1:2.9 1:4 Perfume 1.3 1.3 1.3 1.3 1.3 1.3 Minors (preservatives, NaCI, dyes and 1.5 1.5 1.5 1.5 1.5 1.5 pigments, impurities) ______ ______ _______ ______ _______ ______ Water 16 16 19 17.2 18 16 Hardness �40°C (kg) 3.0-5.0 4.9 4.6 4.8 4.4 4.7 4.5 Yield stress �40°C (Pa) >35 850 700 790 650 770 680 Extrusion Throughput High H H H H H H Bar Slip Subjectivea Slippery (5) 5 5 5 5 5 D Cracking level (0-5) 0-1 1 1 1 2 0 0-1 Rate of wear (%) <35 29 34 29 30 30 31 Mush Objective(g/50cm) <16 16 14.7 14 14 13 13 Mush Subjective Low-M M M M M L ______________________ Medium ______ ______ ______ ______ ______ _____ a) descriptors -Slippery (5), Slightly Draggy (SD), Draggy (D)

J

Example 25

Especially preferred personal washing bars are extruded bar consisting of the ingredients listed in Table 5 with the constraints that: i) the sum of the ingredients can not exceed 100% SO that all or some of the individual ingredients can not be simultaneously present at their maximum levels; ii) the sum of the weights of the polyol, starch and inorganic particles comprises at least about 20% but no more than 30% of the bar by weight; and iii) the composition is both sufficiently hard and pliable that it can be formed into bars at high production rates (the composition is an extrudable mass having a yield stress between 350 and 2000 kPa measured at a temperature of 40° C); and iv) the finished bars have physical properties close to the ideal values as set forth in preceding tables.

Table 7: Highly preferred bar compositions Ingredient Wt% Preferred types Soaps 45-55 Na, K, TEA soaps 90/10 to 60/40 "Strearics"/"Laurics" Structuring system 20-30 5% to 12% polyol (glycerol and/or sorbitol) 7% to 24% starch (natural, pre-gelled, modified) 0-10% insoluble particles (talc, calcium carbonate, clays, aluminates, silicates, polysaccharides, polymers, insoluble soaps) (% by weight of total composition) Water 1320%a preferably less than 20%, more preferably a -in freshly made bar between about 15% and 18% Added soluble salt 0.4 to 0.8 sodium and/or potassium sulfates, carbonates, citrates, phosphates and isethionates Fatty acids 0-1.0 C8-C22 fatty acids -C12114 preferred Bar slip modifiers 0-1 Petrolatum, lanoline, waxes, silicones, polyethylene oxides and high molecular weight polyethylene oxides and mixtures thereof. High molecular weight water soluble polyethylene oxide resins such as WSR N-301 (molecular weight 4,000,000) are effective at relatively low concentrations.

Syndets 0-8 alkyl and alkylethoxy sulfates, alpha olefin sulfonates, acyl isethionates Saponification/ 0-2 NaCI, KCI neutralization electrolytes Adjuvants 0-5 perfumes, colorants, pigments (Ti02), preservatives, opacifiers Skin benefit agents 0-5 especially: antimicrobials, vitamins, essential oils, plant extracts, emollients, and moisturizers