Conventional detergent bars, based on soap for personal washing contain over about 70% by weight total fatty matter (TFM), the remainder being water (about 10-15%) and other ingredients such as colour, perfume, preservatives, etc. In low cost toilet soaps, TFM is generally the most expensive ingredient. Since the level of TFM needed for acceptable detergency is much lower than what is used in conventional toilet soaps, it is desirable to replace TFM with water, air or cheaper fillers, while retaining processability and good bar properties.

Hard non-milled soaps containing moisture of less than 35% are also available. These bars have a TFM of about 30-65%.

The reduction in TFM has been achieved by the use of insoluble particulate materials and/or soluble silicates.

Milled bars generally have a water content about 8-15% and the hard non-milled bars have a water content of about 20- 35%.

In many parts of the world, fabric washing composition as well as hard surface cleaners are produced in a bar form.

These Bars require an acceptable physical strength to retain their structural integrity during handling, transport and use. The hardness of the bars, at the time of manufacture and subsequently, is an especially important property.

Inclusion of certain ingredients to make the bar harder usually results in higher density bars, making the bars considerably smaller and thus less attractive to the consumer and also gritty to feel.

In all these products, which are in bar form, increased water structuring helps in improving the in-use properties of the bar without affecting its physical properties in an economical way. It enables one to manufacture detergent bars cost effectively. It is important to deliver sensory properties such as lather, cleaning, product feel and skin feel without altering the processability and physical properties of the bar and to process the formulations using the existing equipment. This would enable products to be processed by the conventional methods of manufacture and without altering the through-put.

The use of borate compounds or boric acid in personal care products generally is not new. When previously used with soaps, however, sodium tetra borate (Borax) has been used as a soluble scrubber in powdered hand soap compositions of the type used to clean medium to heavy soils found in industrial operations ; or in liquid soaps.

U. S. Patent No. 3,708,425 to Compa, et al., teaches a detergent bar containing about 5 to 60%'by wt. puffed Borax.

This work specifically calls for puffed Borax or other puffed salts to which the user properties of the bar are attributed.

U. S. Patent No. 3, 798, 181 to Vazquez teaches enzymatic detergent bars (not pure soap bars) containing 10-40% synthetic detergent, 0.5-5% enzymes, 5-40% binder (e. g., to help retain water), 20-60% inorganic builder and 12-25% water. Borax may be used as possible inorganic builder.

The bar is a detergent bar which contains enzymes unlike bars of the invention which contain no enzymes.

None of the prior art teaches Borates as water structurants which enables not only the incorporation but even the retention of high amounts of water in the bar without affecting the physical and in-use properties of the bar.

IN 177828 discloses-a process wherein by providing a balanced combination of aluminium hydroxide and TFM it is possible to prepare a low TFM bar having high water content but with satisfactory hardness. The patent teaches the generation. of colloidal alumina hydrate in-situ by a reaction of fatty acid with an aluminium containing alkaline material such as sodium aluminate to form bars which are obtained by plodding.

Our copending application 810/Bom/98 discloses a process of preparing a low TFM composition by a reaction of fatty acid/fat with an aluminium containing alkaline material such

as sodium aluminate solution that specifically has a solid content of 20 to 55% wherein the alumina (Al203) to sodium oxide (Na2O) is in a ratio of 0.5 to 1.55 by weight gives superior bar properties. These bars have improved hardness and smoother feel. This reaction can take place in a broad temperature range of 40 to 95°C. It is also disclosed in (904/Bom/99) that in-situ generation of amorphous alumina by a reaction of fatty acid/fat or an acid precursor of an active detergent in presence of carboxylic acid with an equivalent weight less than 150 with an aluminium containing alkaline material, detergent bars with very high moisture, good processability and improved water retention capacity can be processed.

It has now been found that in-situ generation of borate either alone or in presence of alumina in the process for preparing a detergent bar composition enables the structuring of high amounts of water while maintaining the in-use properties of the bar.

Conventional detergent bars for personal wash contain about 12% moisture. Though it is not feasible to generate processable milled personal wash bars with high moisture (-18%) it is possible using in-situ generated alumina as the structurant. But, these bars tend to lose extra moisture during storage at 45°C. The bars according to the invention not only are capable of structuring higher levels of moisture but also retain the moisture under storage. Losing water from high moisture bars during storage

causes shrinkage of bars leading to reduction in their size which is significantly reduced by the structuring system according to the present invention.

Accordingly, this invention provides an improved process for preparing detergent bar composition comprising the steps of: a. reacting one or more precursors of detergent active with an alkaline material having an elemental ratio of boron to aluminium (B: AI) in the range 1: 0 to 1: 21, wherein the boron containing alkaline material is preferably sodium meta-borate with solids content 20- 60% and the aluminium containing alkaline material is preferably sodium aluminate with a solid content of 20 to 55% wherein the A1203 to Na2O is in a ratio of 0.5 to 1.55 by weight to obtain a mixture of borate and/or borate-alumina and detergent active at a temperature between 25°C to 95°C ; b. adding water to the mixture thus obtained ; c. adding if desired, one or more of other detergent actives, builders and minor additives such as herein described to the mixture of step (a) and/or step (b) ; d. converting the product into bars by conventional method, the ingredients being incorporated in the process in such amounts as to provide a bar composition comprising : from 5 to 70% by weight of detergent active from 0.5 to 30% by weight of borate and/or borate-alumina from 5 to 55% by weight of water and optionally other benefit agents 0-30% of detergent builder

According to a preferred aspect of the invention the elemental ratio of boron to aluminium is 1: 0.63 to 1: 21, more preferably 1: 0.63 to 1: 5.6.

Preferably, the neutralisation of the detergent active is carried out by reacting one or more precursors of detergent active and at least one carboxylic acid with sodium meta borate and sodium aluminate in order to generate amorphous alumina and borate-alumina species. The carboxylic acid mentioned are those which have an equivalent weight less than 150 may be selected from aliphatic monocarboxylic acids that are not fatty acids and their polymers and more preferably they are Ci to Cs carboxylic acids and their polymers. Other suitable carboxylic acids are aliphatic or aromatic di,-tri-, or polycarboxylic acids and hydroxy-and amino carboxylic acids.

It is preferred that the weight ratio of the precursor of detergent active and the carboxylic acid is in the range 1 to 60: 1.

The sodium meta-borate and sodium aluminate in the reaction is at least equal to stoichiometric amount required for the neutralisation of carboxylic acid and the precursor of detergent active.

It is particularly preferred that the precursor of the detergent active is one or more fatty acids/fat to obtain a detergent bar with 15 to 70% by weight of total fatty matter.

The invention is carried out in any mixer conventionally used in soap/detergent manufacture and is preferably a high shear kneading mixer. The preferred mixers include ploughshare mixer, mixers with 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.

Boron and Aluminium containing alkaline material: The boron containing alkaline material is preferably sodium meta-borate with 20-60% solid content. For the purpose of the invention the aluminium containing alkaline material used is sodium aluminate with a solid content of 20 to 55% wherein the A1203 to Na2O is in a ratio of 0.5 to 1.55 by weight. However the specified A1203 to Na2O ratio is preferably 1.0 to 1.5. The elemental ratio of the boron and aluminium in the alkaline material used for neutralisation may be 1: 0 to 1: 21, more preferably 1: 0.63 to 1: 21 and most preferably 1: 0.63 to 1: 5.6.

Detergent active: The detergent active used in the process may be soap or non- soap surfactants. The term total fatty matter, usually abbreviated to 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.

For a soap having 18 carbon atoms, an accompanying sodium cation will generally amount to about 8% by weight. Other cations may be employed as desired for example zinc, potassium, magnesium, alkyl ammonium and aluminium.

The term soap denotes salts of carboxylic fatty acids. The soap may be derived from any of the triglycerides conventionally used in soap manufacture-consequently the carboxylate anions in the soap may contain from 8 to 22 carbon atoms.

The soap may be obtained by saponifying a fat and/or a fatty acid. The fats or oils generally used in soap manufacture may be such as tallow, tallow stearines, palm oil, palm stearines, soya bean oil, fish oil, caster oil, rice bran oil, sunflower oil, coconut oil, babassu oil, palm kernel oil, and others. In the above process the fatty acids are derived from oils/fats selected from coconut, rice bran, groundnut, tallow, palm, palm kernel, cotton seed, soybean, castor etc. The fatty acid soaps can also be synthetically prepared (e. g. by the oxidation of petroleum or by the hydrogenation of carbon monoxide by the Fischer-Tropsch process). Resin acids, such as those present in tall oil, may be used. Naphthenic acids are also suitable.

Tallow fatty acids can be derived from various animal sources and generally comprise about 1-8% myristic acid, about 21-32% palmitic acid, about 14-31% stearic acid, about 0-4% palmitoleic acid, about 36-50% oleic acid and about 0- 5% linoleic acid. A typical distribution is 2.5% myristic acid, 29% palmitic acid, 23% stearic acid, 2% palmitoleic

acid, 41.5% oleic acid, and 3% linoleic acid. Other similar mixtures, such as those from palm oil and those derived from various animal tallow and lard are also included.

Coconut oil refers to fatty acid mixtures having an approximate carbon chain length distribution of 8% C8, 7% Clo, 48% C12, 17% C14, 8% C16, 2% C18 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 and babassu kernel oil, are included within the term coconut oil.

Fatty acid: A typical fatty acid blend consisted of 5 to 30% coconut fatty acids and 70 to 95% fatty acids ex hardened rice bran oil. Fatty acids derived from other suitable oils/fats such as groundnut, soybean, tallow, palm, palm kernel, etc. may also be used in other desired proportions.

Non-Soap detergents: The composition according to the invention will preferably comprise detergent actives which are generally chosen from both anionic and nonionic detergent actives.

Suitable anionic detergent active compounds are water soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphuric acid ester radicals and mixtures thereof.

Examples of suitable anionic detergents are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil ; sodium and potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil ; sodium coconut oil fatty acid monoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof.

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

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or

alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

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

alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans.

It is also possible to include cationic, amphoteric, or zwitterionic detergent actives in the compositions according to the invention Suitable cationic detergent actives that can be incorporated are alkyl substituted quarternary ammonium halide salts e. g. bis (hydrogenated tallow) dimethylammonium chlorides, cetyltrimethyl ammonium bromide, benzalkonium chlorides and dodecylmethylpolyoxyehtylene ammonium chloride and amine and imidazoline salts for e. g. primary, secondary and tertiary amine hydrochlorides and imidazoline hydrochlorides.

Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilizing group, for instance sodium 3- dodecylamino-propionate, sodium 3-dodecylaminopropane sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate.

Suitable zwitterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water- solubilising group, for instance 3- (N-N-dimethyl-N- hexadecylammonium) propane-1-sulphonate betaine, 3-

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

It is especially preferred for personal wash systems of the invention to include up to 30% other liquid benefit agents such as non-soap surfactants, skin benefit materials such as moisturisers, emollients, sunscreens, anti ageing compounds are incorporated at any step prior to step of milling.

Alternatively certain of these benefit agents are introduced as macro domains during plodding.

Builders: The detergency builders used in the formulation are preferably inorganic and suitable builders include, for example, alkali metal aluminosilicates (zeolites), alkali metal carbonate, sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP), citrates, sodium nitrilotriacetate (NTA) and combinations of these. Builders are suitably used in an amount ranging from 1 to 30% by wt.

Benefit agents: Examples of moisturisers and humectants include polyols, glycerol, cetyl alcohol, carbopol 934, ethoxylated castor oil, paraffin oils, lanolin and its derivatives. Silicone compounds such as silicone surfactants like DC3225C (Dow Corning) and/or silicone emollients, silicone oil (DC-200 Ex- Dow Corning) may also be included. Sun-screens such as 4- tertiary butyl-4'-methoxy dibenzoylmethane (available under the trade name PARSOL 1789 from Givaudan) and/or 2-ethyl hexyl methoxy cinnamate (available under the trade name PARSOL MCX from Givaudan) or other UV-A and UV-B sun-screens.

Water soluble glycols such as propylene glycol, ethylene glycol, glycerol, may be employed at levels upto 10%.

Inorganic particulates: Inorganic particulate phase is not an essential ingredient of the formulation but may be incorporated especially for hard surface cleaning compositions. Preferably, the particulate phase comprises a particulate structurant and/or abrasive which is insoluble in water. In the alternative, the abrasive may be soluble and present in such excess to any water present in the composition that the solubility of the abrasive in the aqueous phase is exceeded and consequently solid abrasive exists in the composition.

Suitable inorganic particulates can be selected from, particulate zeolites, calcites, dolomites, feldspars, silicas, silicates, other carbonates, bicarbonates, sulphates and polymeric materials such as polyethylene.

The most preferred inorganic particulates are calcium carbonate (as Calcite), mixtures of calcium and magnesium carbonates (as dolomite), sodium hydrogen carbonate, borax, sodium/potassium sulphate, zeolite, feldspars, talc, koalin and silica.

Calcite, talc, kaolin, feldspar and dolomite and mixtures thereof are particularly preferred due to their low cost and colour.

The inorganic particulate structurants such as alumino silicate may be generated in situ using aluminium sulphate

and sodium silicate in the formulation. It is also possible to incorporate readily available sodium alumino-silicate into the formulation.

Other additives: Other additives such as one or more water insoluble particulate materials such as polysaccharides such as starch or modified starches and cellulose may be incorporated.

Minor additives: In step (b) of the process minor and conventional ingredients preferably selected from enzymes, antiredeposition agents, fluorescers, colour, preservatives and perfumes, also bleaches, bleach precursors, bleach stabilisers, sequestrants, soil release agents (usually polymers) and other polymers may optionally be incorporated up to 10 wt%.

EXAMPLES : The invention will now be demonstrated with the help of typical non-limiting example of the process according to the invention as also with the help of comparative results of the composition prepared by the present invention and beyond the invention.

Process for preparing the soap bar: a. Conventional Process with talc as the structuring system (Samples 1 and 2) A batch of 50 kg soap was prepared by melting a mixture of fatty acids at 80-85°C in a crutcher and neutralising with 48% sodium hydroxide solution in water. Additional

water was added to obtain the moisture content of about 33%. The soap mass was spray dried under vacuum and formed into noodles. The soap noodles were mixed with soda ash, talc, perfume, colour, titanium dioxide in a sigma mixer and passed twice through a triple roll mill. The milled chips were plodded under vacuum and formed into billets. The billets were cut and stamped into tablets. b. In situ generation of alumina as sturcturing system: A batch of 50 kg soap was prepared by melting a mixture of fatty acids at 80-85°C in a crutcher and neutralising with 44% sodium aluminate solution (Sample 3). The sodium aluminate solution was prepared by dissolving solid alumina trihydrate in sodium hydroxide solution at 90-95 °C. Additional water was added to obtain the moisture content of about 33%. The soap mass was spray dried under vacuum and formed into noodles. The soap noodles were mixed with soda ash, talc, perfume, colour, titanium dioxide in a sigma mixer and passed twice through a triple roll mill. The milled chips were plodded under vacuum and formed into billets. The billets were cut and stamped into tablets. c. Process according to the invention : In samples prepared according to the invention the mixture of fatty acids at 80-85°C in a crutcher was neutralised using 40% Sodium meta borate (Sample 4) and a mixture of sodium meta borate and sodium aluminate (44%) in equal proportions (Sample 5). Additional water was added to obtain the moisture content of about

33%. The soap mass was spray dried under vacuum and formed into noodles. The soap noodles were mixed with soda ash, talc, perfume, colour, titanium dioxide in a sigma mixer and passed twice through a triple roll mill. The milled chips were plodded under vacuum and formed into billets. The billets were cut and stamped into tablets.

The samples prepared as described above were tested for parameters such as hardness and water retention by the following procedure.

Water retention: The bars were weighed and stored at room temperature-25- 30°C for 90 days. The weight of the bars were taken periodicaly upto 90 days. The data is presented as % water retained in the bar at the end of 90 days.

Yield Stress: Yield stress quantifies the hardness of a soap bar. The yield stress of the bars at a specified temperature was determined by observation of the extent to which a bar was cut by a weighted cheese wire during a specified time. The apparatus consists of a cheesewire (diameter d in cm) attached to a counter balanced arm which can pivot freely via a ball race bearing. A billet of soap is positioned under the wire such that the wire is just in contact with one edge of the billet. By applying a weight (W g.) directly above the cheesewire a constant force is exerted on the wire which will slice into the soap. The area over which the force acts will increase as the depth of cut

increases and therefore the stress being exerted will decrease until it is exactly balanced by resistance of the soap and the wire stops moving. The stress at this point is equal to the yield stress of the soap. The time taken to reach this point was found to be 30 secs. so that a standard time of 1 min was chosen to ensure that the yield stress had been reached. After this time the weight was removed and the length of the cut (L in Cm) measured. The yield stress is calculated using the semi-empirical formula: Y. S = 3 W x 98.1 Pascal (Pa.) 8 L x d Comparative results of the compositions prepared using conventional process with bars structured using talc or in- situ generated alumina and those according to the present invention are shown in Table 1. The composition details and their results are also described in the Table below.

Table 1 Composition % wt. Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Soap (TFM-Na) 74 70 68 66 67 Alumina(During--12-- neutralisation of the precursor of the detergent active) Borate(During 14 neutralisation of the precursor of the detergent active) Alumina+Borate 13. 0 (During neutralisation of the precursor of the detergent active) Talc 11 11--- Minor ingredients 2 2 2 2 2 Water 13 17 18 18 18 Bar Properties % water after 90 8 12 12 days (at 45°C) Weight loss at 6. 4 9. 7 10. 87 6. 8 6. 8 45°C/100 g bar Yield stress (Pa.) 3.3 X 10'Soft and 3.2 X 10 3. 15 X 105 2. 95X 10 5 difficult to process The data presented in Table 1 show that when the bar is formulated with the conventional material such as talc the level of water that can be incorporated is only up to about

13%. If the water level is increased, the bars are soft and difficult to process.

The bars prepared according to the invention, are processable at higher moisture levels. The bars according to the invention structured with 18% moisture showed ~6% weight loss at 45°C which was similar to the loss in the case of conventional soaps structured with talc having 13% moisture. The bars structured with talc and in-situ generated alumina with-18% water show 9-10% weight loss.

The bars prepared according to the invention, structure higher levels of water have good physical properties and retain higher % of this water during storage at higher temperatures in comparison to the conventional bars with similar water levels, while maintaining the sensory properties of high TFM soaps.