Field of the invention

The present invention relates to a laundry composition in a solid shaped form for direct application to fabric. More particularly, it relates to a soap composition in the form of bars or tablets which are suitable for use in handwashing of fabrics.

Background of the invention

Laundry detergent compositions designed for hand-wash markets predominantly include those in the form of powder, tablet or bars. Laundry bars designed for washing fabrics are formulated to provide effective cleaning in clothes, acceptable sudsing characteristics, slow wear rates, good hardness, durability and low smear properties.

Laundry bar compositions may include soap, synthetic detergent or a combination of soap and synthetic detergent as the main detersive surfactant. In some regions soap-based laundry bars are preferred for laundering fabrics. Laundry soap bar compositions typically contain 60 wt.% to 80 wt.% soaps and around 14 wt.% to 22 wt.% of water and optionally small amounts of inorganic salt and filler.

In the past laundry soap bar manufacturers have been limited to formulations with higher soap content due to processing and/or resulting bar quality constraints. It is desirable to reduce the soap content of such compositions to improve cost savings.

One possible way of reducing overall soap content would be to increase the water content. However, the resultant composition is soft, sticky and cannot be processed into bars using conventional equipment. In general, increasing the water content of laundry bars has the consequence that the bars tend to shrink on storage, leading to stress cracking.

Another possible way of reducing soap content is to include fillers. Use of higher levels of soluble fillers (eg. polyols) tends to produce deterioration in properties perceived by the user, such as lather formation, bar hardness, rate of wear and development of surface mush. Use of insoluble fillers (eg. kaolin) tends to increase the viscosity of the composition again leading to processing difficulties. Typically soap bars include a combination of short chain soap molecules and long chain soap molecules. Handwash consumers prefer bars with good lathering characteristics and cleaning properties and there is a continuing need to improve foam performance in laundry composition. Typically, bars include higher levels of short chain soap molecules and water-soluble unsaturated soap molecules for improving cleaning and lather formation. Long chain soap molecules such as those based on C or higher chain length fatty acid soap are water insoluble and do not contribute significantly to lather formation and cleaning. To enhance lathering a super-fatting agent (C12 fatty acids) may also be used which improve the volume and richness of the lather when added to soap bars in levels of up to about 10 wt.% to 15 wt.%. However, short chain soap molecules and their fatty acid soaps are both expensive commodities and it would therefore be desirable to achieve improvements in foam profile and cleaning properties without recourse to high levels of these ingredients.

When short chain length soap content is minimized use of synthetic (e.g., anionic) surfactant is one way to make up for the loss in the bar user properties and lathering. It is thus a challenge to provide a soap bar composition in which both the use of short chain fatty acid soap and synthetic surfactant is minimized, while maintaining good user properties.

US 4,874,538 (Dawson et. Al, 1989) describes toilet soap bar composition having improved lathering characteristics. The soap bar composition includes a beta-phase soap formation with specific polymer materials which provides bar lathering (volume/ richness) characteristics, both in soft and hard water conditions. This invention does not seek to minimize the level of fatty acid soap and further includes synthetic surfactants.

It is thus an object of the present invention to provide a laundry soap bar composition having lowered levels of the short chain fatty acid soap molecules while maintaining the good user properties and lathering characteristics of the bar.

It is another object of the present invention to provide a low-cost laundry soap bar composition having lower levels of short chain fatty acid soap molecules without compromising on the cleaning efficacy or bar sensorials such as lathering characteristics. It is also an object of the present invention to provide a laundry soap bar composition comprising no or low levels of synthetic surfactant and lower levels of short chain length fatty acid soap while maintaining good user cleaning properties and foaming characteristics.

It is another object of the present invention to provide a laundry soap bar composition which in addition to being conveniently extrudable and stampable does not compromise on the bar integrity and delivers the desired sensorial properties like high lather and low mush.

Summary of the invention

We have now found that by carefully selecting the weight ratio ranges between short chain length fatty acid soap molecule and long chain length fatty acid soap molecule in a soap bar composition having a specific cationic polymer provides for minimizing the amount of short chain length fatty acid soap, while still maintaining satisfactory bar properties, and improved lathering.

According to a first aspect, present invention discloses a laundry soap bar composition comprising: i) fatty acid soap wherein the soap comprises long chain soap molecules having chain length of C14 or greater and short chain soap molecules having a chain length of C12 or below; ii) a cationic polymer; and, iii) 10 wt.% to 35 wt.% water, characterised in that the soap composition has from 15 wt.% to 70 wt.% fatty acid soap and wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2.

According to a second aspect of the present invention disclosed is a process for preparing the laundry soap bar composition according to the first aspect, the process comprising the steps of: i) neutralizing one or more fatty acids or fat with an alkaline material to obtain fatty acid soap; ii) adding water to the fatty acid soap to form a dough mass; iii) adding a cationic polymer to the dough mass; iv) converting the resulting dough mass into a shaped laundry soap bar composition. characterised in that the fatty acid soap comprises long chain soap molecules having chain length of C14 or greater and short chain soap molecules having a chain length of C12 wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 and wherein the shaped laundry soap bar composition comprises from 15 wt.% to 70 wt.% fatty acid soap and from 10 wt.% to 35 wt.% water.

According to a third aspect of the present invention disclosed is a use of a cationic polymer and a fatty acid soap wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 in a laundry soap bar composition comprising 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water for providing improved bar properties.

According to another aspect of the present invention disclosed is a use of a cationic polymer and a fatty acid soap wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 in a laundry soap bar composition comprising 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water for providing improved lather characteristics.

According to another aspect of the present invention disclosed is a use of a cationic polymer and a fatty acid soap wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 in a laundry soap bar composition comprising 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water for providing improved cleaning performance.

By the term “bar” it is meant that the laundry composition is in the form of a shaped solid. The soap bar is in solid form which retains its shape after manufacture and during transport and storage. The term bar also includes other shaped laundry bar composition such as cake form or tablet form. The shaped solid is preferably formed either by a casting route or an extrusion route, more preferably the extrusion route.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilized in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages 5 are weight/weight percentages unless otherwise indicated Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description and claims indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to 10 include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention

According to a first aspect of the present invention disclosed is a laundry soap bar composition which includes a fatty acid soap, a cationic polymer, water and wherein the fatty acid soap has specific weight ratio ranges between the long chain soap molecules and the short chain soap molecules.

Fatty acid soap

According to the first aspect of the present invention disclosed laundry soap bar composition includes fatty acid soap, wherein the fatty acid soap comprises long chain soap molecules having chain length of C14 or greater and short chain soap molecules having a chain length of C12 or below.

The term fatty acid soap denotes the salts of the carboxylic fatty acids. This class of compound includes ordinary alkali metal soaps such as sodium, potassium and ammonium salts of carboxylic fatty acids. Soaps can be made by direct saponification of fats and oils or by the neutralization of free fatty acids. Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil, tallow, fish oil, soya oil, palm oil e.g. sodium and potassium tallow soap. In general, sodium soaps are used in the compositions of the invention, but the soap may be also be selected from 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 from 8 to 22 carbon atoms, preferably from 10 to 18 carbon atoms. They may be described as alkali metal carboxylates of saturated or unsaturated hydrocarbons having from 8 to 22 carbon atoms. The fatty acids may be synthetically prepared example by oxidation of petroleum stocks or by the Fischer-Tropsch process.

Preferably the fatty acid soap for use in the present invention include at least 30 wt.% saturated soaps, i.e., soaps derived from saturated fatty acids, preferably at least 40 wt.%, more preferably 50 wt.%, still more preferably at least 70 wt.% saturated soaps by weight of the fatty acid soap. The fatty acid soap for use in the present invention preferably includes 30 wt.% to 50 wt.% unsaturated fatty acids, preferably 35 wt.% to 50 wt.% unsaturated fatty acid soap.

The fatty acid soap according to the present invention comprises short chain fatty acid soap molecules having a chain length of C12 or below. The short chain fatty acid soap molecules preferably include fatty acid soap having 8 carbon atoms to 12 carbon atoms. These encompass soaps which are derived predominantly from Cs to C12 saturated fatty acid, i.e. lauric acid, but can contain minor amounts of soaps derived from shorter chain fatty acids, e.g., C10. The short chain fatty acid soaps are generally derived in practice from the hydrolysis of nut oils such as coconut oil and palm kernel oil. Short chain fatty acid soap having from 8 carbon atoms to 12 carbon atoms lather quickly. Short chain fatty acid molecules are the saponification products of fatty acids or lauric oils (that is Cs to C12 palm kernel oil, coconut oil) with selected alkali (Na ⁺ and/or K ⁺ ). The short chain fatty acid soap molecules are predominantly saturated.

The fatty acid soap comprises long chain fatty acid soap molecules having chain length of C14 or greater. The long chain fatty acid soap molecules preferably include fatty acid soap having 14 carbon atoms to 22 carbon atoms, still preferably from 16 to 22 carbon atoms, further preferably from 16 to 20 carbon atoms. They may be classified as follows:

"Stearics" soaps which encompass soaps which are derived predominantly from C to C saturated fatty acid, i.e. palmitic and stearic acid but can contain minor level of saturated soaps derived from longer chain fatty acids, e.g., C20. Stearics soaps are generally derived in practice from triglyceride oils such as tallow, palm oil and palm stearin.

“Oleics" soaps which encompass soaps which are derived from unsaturated fatty acids including predominantly oleic acid (Cis:i), linoeleic acid( (Ci8:2), myristoleic acid (Ci4:i) and palmitoleic acid (Ci6:i) as well as minor amounts of longer and shorter chain unsaturated and polyunsaturated fatty acids. Oleics soaps are generally derived in practice from the hydrolysis of various triglyceride oils and fats such as tallow, palm oil, sunflower seed oil and soybean oil.

Long chain fatty acid soap is insoluble in water and help maintain the structure of the bar, but the long chain fatty acid soap does not readily generate lather. Long chain fatty acid soap molecules are the saponification products (typically with sodium counterions) of primarily non- lauric oils with caustic soda. By non-lauric it is meant to include long saturated (Cw and C ) and unsaturated (Ci8:i, Ci8:2, Ci8:s) fatty acids found in palm oil, palm oil stearin, tallow.

In the laundry soap bar composition according to the present invention, the ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2, preferably the ratio is 80:20 to 98:2, still preferably 80:20 to 90:10. Preferably the short chain fatty acid is selected from lauric acid, myristic acid and mixtures thereof. Preferably the short chain soap molecules has an average molecular weight is from 200 to 210 g/mole. Preferably the long chain fatty acid is selected from palmitic acid, stearic acid, oleic acid, linoleic acid and mixtures thereof. Preferably the short chain soap molecules have an average molecular weight is from 265 to 285 g/mole.

Preferably the laundry soap bar composition according to the present invention comprises from 15 wt.% to 70 wt.% fatty acid soap. Preferably the laundry soap bar composition comprises at least 20 wt.%, preferably at least 25 wt.%, still preferably at least 30 wt.% and most preferably at least 35 wt.%, but typically not more than 65 wt.%, still preferably not more than 60 wt.%, still further preferably not more than 55 wt.% and most preferably not more than 50 wt.% fatty acid soap in the laundry soap bar composition.

Cationic polymer

According to the first aspect of the present invention disclosed laundry soap bar composition includes a cationic polymer.

Non-limiting examples of cationic polymers suitable in the present invention are selected from the group consisting of cationic polysaccharides, cationic copolymers of saccharides and synthetic cationic monomers, homopolymers of dimethyldiallyl ammonium chloride, copolymers of dimethyldiallyl ammonium chloride and acrylamide, quaternized vinylpyrrolidone acrylate or methacrylate copolymers of amino-alcohol, cationic homopolymers and copolymers derived from acrylic acid and/or methacrylic acid, polyalkylene imines and ethoxy polyalkylene imines and mixtures thereof. The cationic polymer includes naturally and synthetically derived cationic polymers. Preferably the cationic polymer is a polymer of dimethyldiallyl ammonium chloride (DMDAAC) which includes both the homopolymers and copolymers dimethyldiallyl ammonium chloride (DMDAAC) or mixtures thereof. Preferably the copolymers of dimethyldiallyl ammonium chloride and acrylamide.

Cationic polysaccharides include but is not limited to cationic guar gums, for example hydroxypropyl trimethyl ammonium guar gum and quaternized cellulose ethers. Examples of hydroxypropyl trimethylammonium guar gum (d.s. of from 0.11 to 0.22) available commercially under the trade names Jaguar C-17(RTM), and also Jaguar C-16(RTM), which contains hydroxypropyl substituents (d.s. of from 0.8 to 1.1). Examples of quaternized cellulosic compounds are described in US Patents Nos. 3816616 and 4272515 and which are available commercially from National Starch which includes Celquat.

Cationic polymer is preferably a homopolymer of dimethyldiallyl ammonium chloride. An example of a homopolymer of dimethyldiallyl ammonium chloride (DMDAAC) is that sold under the registered trademark MERQUAT by Lubrizol., Inc. Nonlimiting example includes Merquat™ 100, which is a highly charged cationic dimethyl diallyl ammonium chloride homopolymer. Cationic homopolymer of dimethyldiallylammonium chloride are also known as polyquaternium- 6 polymer. The polyquaternium-6 useful herein preferably has a cationic charge density of at least 3.5 meq/g, more preferably at least 4.5 meq/g, still more preferably at least 5.5 meq/g, and preferably not more than 13 meq/g, more preferably not more than 10 meq/g, still more preferably not more than 7.0 meq/g. Commercially available example of highly preferred polyquaternium-6 polymer include, for example, that having a tradename Merquat 100 available from Lubrizol, has a cationic charge density of about 6.19 meq/g. Cationic homopolymer of dimethyldiallylammonium chloride preferably has a weight average molecular weight of at least 800 g/mol, more preferably at least 1,000 g/mol, still more preferably at least 1,200 g/mol, further preferably at least 10,000 g/mol, most preferably at least 50,000 g/mol but preferably the weight average molecular weight is not more than 1 ,000,000 g/mol, still more preferably not more than 500,000 g/mol, further more preferably not more than 300,000 g/mol, even more preferably not more than 200,000 g/mol. Commercially available example of highly preferred polyquaternium-6 polymer include, for example, that having a tradename Merquat™ 100 available from Lubrizol, has a molecular weight of about 150,000 g/mol.

Although any copolymer of DMDAAC (including terpolymers and polymers of more than three monomers) may be used, the preferred copolymers are DMDAAC/acrylamide and DMDAAC/acrylic acid. The dimethyldiallyl chloride and acrylamide copolymer is a linear water- soluble polymer with a cationic group, which has a high positive charge density and good water solubility. Preferably the cationic polymer is copolymer of acrylamide and diallyldimethylammonium chloride. Commercially available as Merquat™ 550, Merquat™ 550L, Merquat™ 550PR, Merquat™ S, Merquat™ 7SPR, Merquat™ 740, Merquat™ 2200, Mirapol 550,

Polyquart 770/NA and Conditioneze 7. Merquat™ 550, a highly charged cationic copolymer prepared with dimethyl diallyl ammonium chloride and acrylamide. These copolymers include around 50 wt.% acrylamide and 50 wt.% dimethyldiallyl ammonium chloride. Although any ratio of DMDAAC and comonomer will work, the preferred ratio (by weight) of the two monomers in the DMDAAC/comonomer (example acrylamide) copolymer is preferably from 10/90 to 90/10 as DMDAAC/comonomer, more preferably from 80/20 to 20/80. The preferred ratio (by weight) of the three monomers in the DMDAAC/acrylamide/acrylic acid copolymer is preferably from 40/20/40 to 10/80/10 as DMDAAC/acrylamide/acrylic acid, more preferably from 25/50/25 to 20/60/20.

Other cationic polymers include cationic polyamide polymers such as the low molecular weight adipic acid/diethylene-triamine polyamide and the copolymers of vinylpyrrolidone and dimethylaminoethyl methacryate quaternised with dimethyl sulphate (Gafquat 755, GAF Corporation) described in US Patent No. 4080310; the graft cationic copolymer containing N- vinylpyrrolidone, dimethylaminoethyl methacrylate and polyethylene glycol described in US Patent No. 4048301; the mineral acid salts of the amino-alkyl esters of homo- and copolymers of unsaturated carboxylic acids having from 3 to 5 carbon atoms described in US Patent No. 4009256; and the polymers of etherified starch described in US Patent No. 3186911.

Preferably the cationic polymer is soluble or dispersible in water to a level of at least 1% by weight preferably at least 5% by weight at 25°C. The laundry soap bar composition according to the present invention comprises from 0.01 wt.% to 5 wt.% by weight of cationic polymer. Preferably the soap bar composition comprises at least 0.05 wt.%, still preferably at least 0.1 wt.%, still preferably at least 0.2 wt.%, most preferably at least 0.3 wt.% of the cationic polymer, but typically not more than 3 wt.%, still preferably not more than 1 wt.%, most preferably not more than 0.5 wt.% cationic polymer based on the weight of the soap bar composition. Preferably the soap bar composition includes from 0.1 wt.% to 2 wt.% by weight of cationic polymer, most preferably from 0.3 wt.% to 0.5 wt.% by weight of cationic polymer.

Water

According to the first aspect, disclosed laundry soap bar composition includes from 10 wt.% to 35 wt.% water, preferably from 25 wt.% to 30 wt.%, still preferably from 30 to 35 wt.%. The soap bar composition of the invention is capable of stably retaining high amount of water in the range from 10 wt.% to 35 wt.%, still preferably at least 15 wt.%, further preferably at least 20 wt.%, still more preferably at least 23 wt.% furthermore preferably at least 25 wt.% but the amount of water in the laundry soap bar composition is preferably not more than 35 wt.%, still preferably not more than 33 wt.%, most preferably not more than 30 wt.%.

The preferred water content levels quoted above refers to freshly made laundry soap bars where water content is measured within 8 hours. This quantity is designated as the "initial water level" or "initial water content" of the freshly prepared laundry soap bar composition and is also known as the "nominal water content" or "nominal water level" of the composition. The water present in the bar at room temperature (approximately 25°C) includes "free" water and bound water of crystallisation. The water content in the bar after 4 weeks of storage may reduce to a maximum of 5 wt.% to 7 wt.% of the initial water content and thereafter stabilizes with no further significant moisture loss.

As is well known, soap bars are subject to drying out during storage, i.e. , water evaporates from the bar when the relative humidity is lower than the partial vapor pressure of water in equilibrium with the bar composition and depends on the rate of diffusion of water from the bar. 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 differ from the nominal water content of the bar immediately after manufacture.

Optional ingredients

In addition to the components described above, the laundry soap bar composition of the present invention can contain a wide variety of optional ingredients. These optional ingredients include but are not limited to, synthetic surfactants, water soluble fillers, water-insoluble fillers, organic and inorganic adjunct materials, alkaline materials, processing aids, minor additives, dyes, electrolytes, chelating agents.

Synthetic surfactants:

Optionally the laundry soap bar composition of the present invention includes a synthetic surfactant. Preferably the synthetic surfactant is a non-soap anionic surfactant including but not limited to alkali metal and alkaline earth metal salts of higher alkyl aryl sulphonate surfactant, higher alkyl sulphate surfactant, higher fatty acid monoglyceride sulphate surfactant or mixtures thereof. Examples of mild synthetic surfactants include alkyl glyceryl ether sulfonates (AGS), anionic acyl sarcosinates, methyl acyl taurates, N-acyl glutamates, alkyl glucosides, acyl isethionates, alkyl sulfosuccinates, alkyl phosphate esters, ethoxylated alkyl phosphate esters, ethoxylated alkyl alcohols, alkyl sulfates, alkyl ether sulfates, methyl glucose esters, protein condensates, mixtures of alkyl ether sulfates and alkyl amine oxides, betaines, sultaines, and mixtures thereof. Included in the synthetic surfactants are the alkyl ether sulfates with from about 1 to about 12 ethoxy groups, especially ammonium and sodium lauryl ether sulfates. Alkyl chain lengths for these surfactants are about Csto C22, preferably C to C .The alkyl portion of such synthetic surfactants are often derived from natural sources of fatty acids which are the same as for the fatty acid soaps.

The composition of the present invention includes less than 5 wt.%, preferably less than 3 wt.%, still preferably less than 1 wt.%, still more preferably less than 0.1 wt.% of the synthetic surfactant. Preferably the composition of the present invention is substantially free of the synthetic surfactant. By substantially free it is meant that there is no deliberately added synthetic surfactant in the laundry soap bar composition of the present invention. The composition of the present invention includes less than 5 wt.%, preferably less than 3 wt.%, still preferably less than 1 wt.%, still more preferably less than 0.1 wt.% of the non-soap anionic surfactant. Preferably the composition of the present invention is substantially free of the non-soap anionic surfactant. By substantially free it is meant that there is no deliberately added non-soap anionic surfactant in the laundry soap bar composition of the present invention.

Soluble fillers:

Optionally the composition of the present invention includes a soluble filler. The soluble fillers consist of a polyhydric alcohol (also called polyol) or mixture of polyols. Polyol is a term used herein to designate a compound having multiple hydroxyl groups (at least two, preferably at least three) which is highly water soluble, preferably freely soluble, in water. Many types of polyols are available including but not limited to relatively low molecular weight short chain polyhydroxy compounds such as glycerol and propylene glycol; sugars such as sorbitol, mannitol, sucrose and glucose; modified carbohydrates such as hydrolyzed starch, dextrin and maltodextrin, and polymeric synthetic polyols such as polyalkylene glycols, for example polyoxyethylene glycol (PEG) and polyoxypropylene glycol (PPG). Especially preferred polyols are glycerol, sorbitol, mannitol and their mixtures. Most preferred polyol is glycerol. Preferably the bars of the invention comprise from 0 wt.% to 8 wt.%, preferably 0.5 wt.% to 7.5 wt.%, still preferably from 1 wt.% to 7 wt.%, most preferably less than 6 wt.% soluble fillers by weight of the composition. Preferably the soap bar composition includes from 0.5 to 6 wt.% polyol, preferably glycerol.

Organic and inorganic adjunct materials:

Non limiting examples of organic adjunct material may include suitable starchy materials such as natural starch (from corn, wheat, rice, potato, tapioca and the like), pre-gelatinzed 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. The organic adjunct material may also be particulate materials which include insoluble polysaccharides such as crosslinked or insolubilized starch and cellulose, synthetic polymers or mixtures thereof. The composition of the present invention includes less than 5 wt.%, preferably less than 3 wt.%, still preferably less than 1 wt.%, still more preferably less than 0.1 wt.% of the organic adjunct materials. Preferably the composition of the present invention is substantially free of the water-soluble organic adjunct material. By substantially free it is meant that there is no deliberately added organic adjunct material in the laundry soap bar composition of the present invention. Non-limiting examples of the inorganic adjunct material includes particulate zeolite, calcite, dolomites, feldspars, silica, other carbonates, bicarbonates, and talc. Most preferred are precipitated calcium carbonate, calcium carbonate (as calcite), kaolin, silica, talc. Talc is a magnesium silicate mineral, with a sheet silicate structure and a composition MgsSi4(OH)22 and may be available in the hydrated form. Examples of other optional insoluble inorganic particulate adjunct material includes aluminates, phosphates, insoluble sulfates, borates, sodium carbonate, calcium carbonate, magnesium sulphate, clay and combinations thereof.

The composition of the present invention includes from 0 wt.% to 12 wt.% of the inorganic adjunct material, preferably 2 wt.% to 10 wt.% of the inorganic adjunct material by weight in the laundry soap bar composition.

Alkaline material:

The alkaline material used for neutralization of the acid precursor soap active is selected from a silicate, carbonate, hydroxide, alkaline aluminium-containing compounds such as aluminates phosphate and mixtures thereof. Preferably the amounts of alkaline materials used is at least equal to stoichiometric amount required for the neutralization of the precursor of soap active. For the purpose of the invention the especially preferred alkaline material used for the neutralization of the detergent active is sodium silicate, sodium hydroxide, sodium aluminate, sodium carbonate.

Silicate structuring agent:

The composition of the present invention preferably includes a silicate compound as the structuring agent. The silicate compound is preferably an alkali metal silicate or alkaline earth metal silicate. Preferably the alkali metal silicate is sodium silicate or potassium silicate. Preferably the alkaline earth metal silicate is calcium silicate or magnesium silicate. Most preferably the silicate compound is sodium silicate, magnesium silicate, or calcium silicate. More preferably sodium silicate, calcium silicate, sodium alumino silicate or mixtures thereof. Most preferably the silicate compound is sodium silicate. Sodium silicate includes compounds having the formula (Na2O) _x SiC>2. The weight ratio of Na2<D to SiC>2 could vary from 1 :1.5 to 1.3.8. Grades of sodium silicate with ratio from about 1 : 2 to 1 :2.85 are called alkaline silicate and with ratios from 1 :2.85 to about 1 :3.75 are called neutral silicate. Forms of sodium silicate that are available include sodium metasilicate (Na2SiO3), sodium pyrosilicate (Na6Si2O?), and sodium orthosilicate (Na4SiO4) It is preferred as per this invention that alkaline sodium silicate is used Especially preferred is alkaline sodium silicate with a ratio of 1 :1.8 to 2.5. It is preferred that the soap bar comprises from 0.01% to 8 wt% sodium silicate, preferably 3 wt.% to 6 wt.% on dry weight basis.

Preferably the silicate structuring agent may be formed in-situ during the processing of the soap bar composition. When the silicate structuring agent is calcium silicate, it is preferably generated in-situ by mixing a sparingly water-soluble calcium compound with the alkali metal silicate to form calcium silicate. The alkali metal silicate is preferably sodium silicate. The sparingly water- soluble calcium compound has a water solubility less than 2 g/litre at a temperature of 25°C. The source of calcium is preferably chosen from calcium oxide, calcium hydroxide, calcium carbonate, calcium chloride, calcium sulphate and combinations thereof., more preferably the calcium compound is calcium hydroxide, calcium sulphate or mixtures thereof. Preferably the sparingly water-soluble calcium compound is chosen from calcium hydroxide or calcium sulphate, most preferably calcium hydroxide. Preferably the soap bar composition is obtainable by a process comprising the step of adding a silicate structuring agent wherein the silicate structuring agent is calcium silicate, and wherein the calcium silicate is generated by mixing a sparingly water-soluble calcium compound with an alkali metal silicate to form calcium silicate. The alkali metal silicate is preferably sodium silicate.

The silicate structuring agent may be aluminium silicate or sodium aluminium silicate. Preferably the in-situ generation of aluminium silicate structuring agent is by reacting precursor material selected from (a) soluble aluminium salt and silicate salt or (b) sodium aluminate and alkali metal silicate. It is preferably generated in-situ using a source of monomeric aluminium to condense with silicate anion. The preferable source of monomeric aluminium is aluminium sulphate and the generation of the silicate structuring agent is by reacting aluminium sulphate and alkaline sodium silicate to form sodium alumino-silicate into the formulation. The aluminosilicate structuring agent is preferably present in an amount in the range of 0.5 wt.% to 10 wt.% % by weight of the soap bar composition. According to a preferred process, the present invention involves the step of adding a further silicate structuring agent wherein the further silicate structuring agent is an aluminium silicate or sodium aluminium silicate, and wherein the aluminium silicate or sodium aluminium silicate is generated by (a) reacting soluble aluminium salt and silicate salt or (b) reacting sodium aluminate and alkali metal silicate.

The silicate compound may also be a magnesium silicate, preferably a hydrated magnesium silicate preferably in an amount from 0 wt.% to 10 wt.% preferably 2 wt.% to 5 wt.% in the composition. But typically, the composition has 0 wt.% magnesium silicate in the form of talc or clay such as kaolin.

It is preferred that the soap bar composition comprises from 0.1 wt.% to 20 wt.% silicate structuring agent, preferably sodium silicate, calcium silicate or sodium aluminium silicate, more preferably from 2 wt.% to 20 wt.%, still more preferably from 2 wt.% to 15 wt.%, further preferably 3 wt.% to 10 wt.% on dry weight basis.

Minor additives:

Non-limiting examples of optional minor additives which may be included in the laundry bar composition of the present invention includes colorants, preservatives, perfumes, other polymers which may be incorporated up to 10 wt.% in the composition. Perfumes may be optionally present at a level of from about 0.1 wt.% to 1.5 wt.% of the composition. Any perfume known to the person skilled in the art may be used and not limiting to perfume oil, encapsulated perfume oil.

Optionally the composition of the present invention includes electrolytes. Electrolytes as per this invention include compounds that substantially dissociate into ions in water. Electrolytes as per this invention are not ionic surfactants. Suitable electrolytes for inclusion in the soap making process are alkali metal salts. Preferred alkali metal salts for inclusion in the composition of the invention include sodium sulfate, sodium chloride, sodium acetate, sodium citrate, potassium chloride, potassium sulfate, sodium carbonate and other mono or di or tri salts of alkaline earth metals, more preferred electrolytes are sodium chloride, sodium sulfate, sodium citrate, potassium chloride and especially preferred electrolyte is sodium carbonate, sodium chloride, sodium citrate or sodium sulphate or a combination thereof. For the avoidance of doubt, it is clarified that the electrolyte is a non-soap material. The composition of the present invention includes from 0.5 wt.% to 5 wt.%, preferably 0.5 wt.% to 3 wt.%, more preferably 1 wt.% to 2.5 wt.% electrolytes by weight of the composition. More preferably the composition of the present invention has less than 4.2 wt.% electrolytes, still preferably less than 3 wt.% further preferably less than 2 wt.% electrolytes, preferably wherein the electrolytes are other than sodium chloride, sodium citrate or mixtures thereof. Most preferably the composition of the present invention does not require any electrolytes.

Chelating agents:

Optionally the composition of the present invention includes a chelating agent, the chelating agents may be selected from but not limited to ethylene diamine tetra acetic acid (EDTA), ethylene hydroxy diphosphonic acid (EHDP) or mixtures thereof. The chelating agent is preferably present in an amount ranging from 0.01 wt.% to 1 wt.%. Non-phosphate chelating agents like methylglycinediacetic acid and salts thereof are also preferred.

Soap bar composition

The laundry soap bar composition according to the present invention retains the high-water content in the bar during storage and delivers excellent feel, hardness, cleaning and lathering properties. Preferably the laundry bar composition of the present invention is prepared in the form of a bar by any conventional methods which includes frame cooling method (cast bar route) or milled and plodded route (extrusion route). Preferably the composition is an extruded laundry soap bar composition and has high level of water and yet is easy to extrude and stamp. pH:

The laundry soap bar composition according to the present invention has a pH from 8 to 13, preferably 8 to 11 , preferably from 9 to 11 , more preferably from 9.5 to 10.5 when measured using a 10 wt.% solution in deionised water at 25°C.

Total fatty matter:

The term “Total Fatty Matter” or TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soap without taking into account the accompanying cations. The soap bar composition according to the present invention preferably has a TFM in the range from 15% to 70%, more preferably the TFM is in the range from 15% to 65%, still preferably from 30% to 65%, further preferably 40% to 60%, still preferably from 40% to 55%. Shape:

The laundry soap bar composition according to the present invention may take any shape. The bars according to the present invention have low rates of water loss, by which it is meant the bar typically has excellent water retention and relatively low amounts of shrinkage both upon stamping and upon storage and use.

Hardness:

The laundry soap bar composition of the present invention has a hardness expressed as Kg force required to move the probe for a prespecified distance. The hardness is measured by a Taxtmeter. The bar whose hardness is to be measured is placed onto the testing platform. Then the probe of the measuring instrument is placed close to surface of the bar composition without touching it. Next the instrument is started, and the force required to reach a preset target distance is measured and the observation is recorded. Preferably the instrument reading is from 1300 to 3000 force (RT) in Kg at the target penetration distance of around 10 to 40.

Density:

The laundry soap bar composition according to the present invention has a density ranging from 0.8 to 1.3, preferably from 1.01 to 1.15 grams per cubic metre. One significant advantage of the present invention is that it allows for lowering the levels of the shorter chain fatty acid soap without significantly affecting the bar density compared to a conventional laundry soap bar composition having a higher amount of fatty acid soap.

Iodine Value:

It is preferred that the laundry soap composition according to the present invention includes soap having an Iodine Value in the range of 30 to 55 more preferably in the range of 30 to 50 and most preferably in the range of 30 to 45. The Iodine values of the composition of the present invention is measured by Wijs 20 Method, The American Oil Chemists' Society (AOCS) Official Method Cd 1-25, Revised 1988.)

Iodine Value is the measure of degree of unsaturation of oils. Iodine value, also called Iodine Number is the measure of the degree of unsaturation of an oil, fat, or wax, i.e., the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax. Saturated oils, fats, and waxes take up no iodine; therefore, their iodine value is zero; but unsaturated oils, fats, and waxes take up iodine. The more iodine is attached, the higher is the iodine value.

Process for preparing the laundry soap bar composition

According to a second aspect of the present invention disclosed is a process for preparing the laundry soap bar composition according to the first aspect, the process comprising the steps of: i) neutralizing one or more fatty acids or fat with an alkaline material to obtain fatty acid soap; ii) adding water to the fatty acid soap to form a dough mass; iii) adding a cationic polymer to the dough mass; iv) converting the resulting dough mass into a shaped laundry soap bar composition, characterised in that the fatty acid soap comprises long chain soap molecules having chain length of C14 or greater and short chain soap molecules having a chain length of C12 wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 and wherein the shaped laundry soap bar composition 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water.

The laundry soap bar composition according to the present invention may be produced on a commercial scale by any of the processes known to a person skilled in in the art. Preferably the soap bar composition of the present invention is prepared using the extrusion route. Preferably using a ploughshare mixer (PSM) process or a crutcher/Mazzonni/spray drier process.

The present invention also relates to a process to prepare a soap bar composition according to the present invention comprising the step of including substantially all of the cationic polymer to the soap when it is being produced during the saponification step or after the dough mass is produced but before it is converted into a shaped laundry soap bar composition. Preferably, when the cationic polymer is added after the dough mass is produced it is preferably combined with the perfume and sprayed onto the dough mass before the step of converting the dough mass into a shaped laundry bar composition preferably by an extrusion process.

The fatty acids used for neutralization may be of a single type or a mixture of fatty acids.

Preferably the fatty acids are a mixture of different fatty acids. The fats used are a combination of those which provide the desired amounts of short chain fatty molecules and long chain fatty molecules. In the context of the present invention, the term fats also include oils. The neutralization step is achieved by using an alkaline material preferably selected from silicate, carbonate, hydroxide, alkaline aluminium-containing material such as aluminate, a phosphate or mixtures thereof to form fatty acid soap, preferably the alkaline material is a hydroxide or silicate. Still preferably the alkaline material used for neutralization is sodium hydroxide or potassium hydroxide.

Crutcher process:

In the crutcher process for preparing the laundry soap bar composition firstly a mixture containing fatty acids or oils/fats with the required ratio range of fatty acid molecules with shorter chain length of C12 or below and fatty acid molecules with longer chain length of C14 or higher are taken in the crutcher maintained at a temperature of 50°C to 90°C. The oils used may be selected from distilled fatty acids or neutral oils. Next an alkali preferably sodium hydroxide or potassium hydroxide is added in an amount required for achieving complete saponification of the oils/fats. The temperature of crutcher is increased to a range from 75°C to 120°C. Preferably after the saponification, chelating agents, cationic polymer, soluble fillers, inorganic fillers, adjunct materials (sodium silicate, hydrated magnesium silicate), colorants, added water, alkaline materials (carbonates) and perfume is added to form the soap dough mass.

In the second drying step, the soap mass is dried to reduce the moisture content of the mix to around 10 wt.% to 45 wt.%. The drying step on a commercial basis may be achieved by several different methods. The cooled dough mass is then scraped from the roll to form chips and dried to a specific moisture level in a tunnel dryer. A modern technique for the drying is known as spray drying. This process directs molten soap mass to the top of a tower via spray nozzles. The soap mass sprayed to form dried soap mix hardens and then dries in the presence of a current of heated air. Vacuum may be applied to facilitate removal of water, preferably the vacuum of 50 mm Hg absolute pressure is provided. The dried soap mix is then extruded to form soap noodles having a water content of 10 wt.% to 45 wt.%.

In the third plodding step, the dried soap noodles are transferred to a plodder. A conventional plodder is set up with the barrel temperature at about 90° F. (10°C to 32°C.) and the nose temperature at about 110°F. Preferably the plodding temperature of the dried soap noodles is carried out at a temperature of 40°C to 60°C. The plodder used is a dual stage twin screw plodder that allows for a vacuum of about 40 to 65 mm Hg between the two stages. The soap log extruded from the plodder is typically round or oblong in cross-section and is cut into individual plugs. These plugs are then preferably stamped on a conventional soap stamping apparatus to yield the finished shaped laundry soap bar composition. After stamping the finished soap bar is packaged in desired packaging material which may be selected from laminate, films, paper or combinations thereof.

In a preferred process, prior to plodding dried soap noodles may subjected to one extra mixing and crushing step where noodles will be added in to Z arm high share sigma mixer in which adjunct ingredients such as colorants, preservatives, perfume are added and mixed thoroughly to combine all the ingredients. Further to this, the mix from the sigma mixer may be preferably subjected to a milling step. In the three-roll soap mill the amalgamated mixture is passed through the rolls set at a temperature from 8°C to 35°C to obtain a homogenous mix, This, is an intimate mixing step where the soap mix is subjected to compression and an intense shearing action. After mixing in the mill the mix is transferred to the plodder.

Ploughshare mixer (PSM) process:

In the ploughshare mixer (PSM) process for preparing the laundry soap bar composition firstly a mixture containing fatty acids or oils/fats with the required ratio range of fatty acid molecules with shorter chain length of C12 or below and fatty acid molecules with longer chain length of C14 or higher are neutralized with alkali material, preferably sodium hydroxide. This step of adding sodium hydroxide is continued until the fatty acid or fats/oils is completely neutralised. When the saponification is over, cationic polymer, water, glycerine, chelating agents, soluble fillers, inorganic fillers, adjunct materials (sodium silicate, hydrated magnesium silicate), colorants, alkaline materials (carbonates) are added to form a dough mass.

The main parts of a typical plough share mixer are a jacketed barrel, axial rotating shaft through the centre of the barrel (longitudinally), plough-shaped blades mounted on the axial shaft, and chopper. The ploughs and the high-speed chopper are the mixing elements. While using PSM technology, the temperature of the dough mass would be kept from 90°C to 100°C. After the mixing phase, the blower is switched on which supplies ambient air for cooling the dough mass and removes the moisture. The final dried soap mix is received at 80 to 85°C. The resultant dried soap mix has a moisture content of 10 wt.% to 35 wt.% and is further processed and plodded into homogenized soap chips or noodles. The soap noodles/chips are then processed into finished shaped laundry soap bar composition.

According to a third aspect of the present invention disclosed is a use of a cationic polymer and a fatty acid soap wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 in a laundry soap bar composition comprising 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water for providing improved bar properties.

According to a further aspect of the present invention disclosed is a use of a cationic polymer and a fatty acid soap wherein the weight ratio between the long chain soap molecules to the short chain soap molecules is from 85:15 to 98:2 in a laundry soap bar composition comprising 15 wt.% to 70 wt.% fatty acid soap and 10 wt.% to 35 wt.% water for providing improved lather characteristics.

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

Examples

Laundry soap bar compositions according to the present invention were prepared using the formulation as shown in Table 1. The fatty acids/fats according to the required blend was weighed and neutralized using sodium hydroxide. Thereafter the water, cationic polymer and other ingredients as shown in the table 1 were added, and the mixture was plodded and then extruded to form a shaped laundry bar composition.

Measurement of the bar parameters a) Bar Hardness

Bar hardness refers to the hardness of the bar after manufacture which gives an indication of the processability, strength and retention of structural integrity during handling, transport and use.

Bar hardness was determined by using a TA-XT Express Texture Analyser has a 30° conical probe which penetrates into a soap bar sample at a specified speed to a pre-determined depth. The resistance generated at the specified depth is recorded. The bar whose hardness is to be measured is placed onto the testing platform. Then the probe of the measuring instrument is placed close to surface of the bar composition without touching it. Next the instrument is started, and the force required to reach a preset target distance is measured and the observation is recorded (force in g, gf).

This number can be related to the yield stress (ref 2), which has long been known to be an important determinant of processability and is also related to in-use performance. The hardness of the bar was measured of the freshly prepared bars and after 24 hours of storage. b) Measurement of the pH of the laundry soap bar composition

The pH of the laundry soap bar composition was measured in a 10% solution with distilled water at 25°C. c) % rate of wear measurement:

Rate of wear refers to the amount of the bar loss during use which is measured by its weight.

Step 1 : Preconditioning step

The laundry soap bar was cut into a piece with the following dimension, 8.5cm x 5 cm.

A damp cloth was placed in a soap dish, the working face of the cut soap bar was placed on this soap dish touching the damp cloth and was transferred into a sealed polyethylene pouch. The soap bar was left undisturbed for 1 hour.

After an hour the soap bar placed on the soap dish was removed from the pouch and the soap dish was kept aside. A cotton cloth piece measuring 65cm x 60 cm was immersed in water with a hardness of 15 FH and after the cloth piece was fully soaked it was removed from water and the water allowed to drip out. Once no more water dripped from the cloth piece, the cloth piece was placed on a flat metal or plastic tray and the surface of the cloth was flattened and any trapped bubbles were smoothened out.

Next the laundry soap bar was removed from the soap dish and fixed to the bar holder. The working face of the laundry soap bar was now applied onto the damp cotton cloth piece resting on the plastic or a flat metal tray along the length of the damp cotton cloth (length 60 cm) by moving the holder from one edge of the cotton cloth to the other edge of the cotton cloth in each stroke. Two such strokes were applied such that the strokes were non overlapping along the length of the damp cotton cloth. This completes the preconditioning step. At this stage, the weight of the bar was measured and the weight of the bar along with the holder was recorded (Wo).

Step 2: Rate of wear evaluation

After the weight of the bar is determined, the working face of the bar is rubbed again in 5 nonoverlapping strokes along the length of the damp cloth piece by moving the holder from one edge of the cloth piece to the other edge of the cloth piece covering a distance of 60 cm. After 5 strokes the weight of the bar along with the holder is measured and recorded (W). The % rate of wear is then calculated as follows:

Weight loss over 3 metres (60cm x 5 strokes) = Wb - W

The average weight loss over five (5) times the effective cloth length corresponds to weight loss over three metres (3 m) for a given product - and can be expressed as weight loss per 10 metres of application to the fabric as:

Weight loss per 10 metres = weight loss over 3 metres x 10 d) Determination of the sog and mush

Sog mush refers to the ingress of water from the atmosphere into the bar and relates to the cause of sogginess of the bar.

To measure the sog mush of the prepared laundry bar composition the following process was followed.

Step 1 : preconditioning step

A cloth piece was placed in a soap basin and 10 mL water was added. Thereafter the laundry bar composition was placed in the soap basin and the soap basin along with the laundry soap bar composition was placed in a sealed pouch and left undisturbed for a period of 1 hour.

Step 2: Mush evaluation

At the end of the 1 hour the laundry soap bar composition was removed from the sealed pouch. A fresh cloth piece (measuring 40 cm x 25 cm) was taken and immersed in water to wet the cloth piece. Thereafter the cloth piece was removed and allowed to drip. The cloth piece was next placed on a flat surface and spread and smoothened on the surface. Any excess water was dabbed and removed. The preconditioned laundry soap bar composition was placed in the holder at one end of the wet cloth piece and gently pulled to the other end of the cloth piece. This procedure was repeated twice once on the top surface of the cloth piece and then on the other surface of the cloth piece. Thereafter the weight of the laundry soap bar was measured and recorded (W1 , grams). Next the laundry soap bar was again placed in the soap basin and transferred to a sealed pouch and left undisturbed for 4 hours.

Step 3: Mush evaluation

At the end of 4 hours the laundry soap bar was removed from the sealed pouch. The weight of the laundry soap bar was measured and recorded (W2). Next the soft mush layer on the laundry soap bar was gently scrapped across the surface of the bar and along the sides of the bar using a spatula. Now, the weight of the laundry soap bar was measured and recorded (W3) for the third time. After this the laundry soap bar was left undisturbed and any cracking of the bar is assessed visually after a day.

The sog mush was calculated using the following formula

Weight loss over 30cm ² = [(W1 - W3)*30]/Area (40cm ² )

Mush over 30cm ² = [(W2 - W3)*30]/Area (40cm ² ) e) Measurement of the lather

Soil lather refers to foam generated during wash by which the consumer controls the product dosage.

Step 1 : preconditioning step

A cloth piece was placed in a soap basin and 10 mL water was added. Thereafter the laundry bar composition was placed in the soap basin and the soap basin along with the laundry soap bar composition was placed in a sealed pouch and left undisturbed for a period of 1 hour.

Step 2: lather evaluation

A white terry towel measuring 40 cm x 25 cm was immersed in water with a hardness of 15FH and when it is fully soaked, the terry towel was removed from water and allowed to drip out until no further drops come out. The terry towel was next placed on a flat metal tray and any wrinkles and bubbles were removed and the surface of the towel was smoothened.

Laundry bar was taken, and the test face of the bar was placed in the holder. The bar was moved from an edge of the towel towards the other edge of the towel such that the bar covers the entire length of the towel. This process was repeated twice. The strokes were nonoverlapping. Next 100 ml of water (15°FH hardness) was poured over the fabric and the towel was rubbed 8 times at each corner. The towel was then squeezed to remove all the water and lather out of the towel into a measuring cylinder. Another 20mL of water was added onto the towel and any lather and water remaining on the towel was scrapped and transferred into the measuring cylinder. The amount of lather generated was calculated as follows -

Volume of lather (in mL) = Total volume of water and lather - volume of water.

Table 1 *Blend is a fatty acid soap with a blend of long chain fatty acid soap molecules and short chain fatty acid molecules.

^& Cationic polymer is Merquat™ 100 from Lubrizol. From the results provided in Table 1, it can be inferred that laundry soap bar composition according to the present invention having the short chain fatty acid molecules and the long chain fatty molecules in the claimed ratio ranges in presence of the cationic polymer provides acceptable bar properties such as hardness, rate of wear and mush values. It was further found that the laundry soap bar composition according to the present invention provides improved lather stability which is desirable characteristics for consumer acceptance.