TECHNICAL FIELD The present invention relates to a shaped solid cleaning composition and a method of cleaning a substrate, in particular a fabric substrate.

BACKGROUND AND PRIOR ART

Two-step reactive cleaning methods involving contacting of a fabric with two reactive components in succession in an aqueous media are known. Typically, one of the reactive components comprises fatty acid and/or other acidic materials and the other component comprises alkaline material.

GB338121 (Marquardt and Walter, 1930) describes a process of washing by adding together or one after another two components to the wash where the first component comprises saponifiable fatty acids such as oleic acid, palmitic acid, or stearic acid and the second component comprises alkaline saponifying agents such as sodium carbonate, sodium bicarbonate or sodium hydroxide.

The above process involves fatty acids which are not readily soluble in water and solvents are used to solubilize fatty acids to facilitate their uniform application to fabrics. However, use of solvents is a cause of concern from safety and environmental point of view.

Other approach is to use an emulsifying agent for forming an aqueous emulsion of fatty acid to facilitate uniform application of fatty acids to fabrics.

FR1460904 (Kornbaum Simon, 1966) describes a process of washing in which aqueous emulsion of saponifiable fatty acids is combined with the alkaline wash solution. Fatty acids are preferably selected from oleic acid or low-melting fatty acid mixture and emulsifying agent is a low HLB nonionic surfactant. GB333177 (Rayner, 1930) describes a process of washing consisting of successively treating the material to be washed with a dilute emulsion of saponifiable fatty acids and with a dilute alkali to generate soap in-situ. GB501422 (Pollard, 1939) describes a process for washing articles with a fatty acid component and an alkali component where the aqueous fatty acid emulsion comprises methyl cyclohexanol.

Use of emulsifying agents in the above cited prior art increases cost without providing any additional cleaning benefit. Stability of such emulsions, particularly at relatively low temperatures is another problem which manifests in de-emulsification at temperature below freezing point. Furthermore, application of emulsions to fabric is relatively less convenient and leads to wastage as emulsion disperses in the aqueous medium particularly when mechanical force is applied in cleaning, causing the reactive components to react away from the fabric surface in the aqueous medium rather than in-situ on or near the fabric surface.

EP11767501 (Procter and Gamble, 2002) describes a process of washing a fabric by successively treating the fabric, in any order, with a first component and a second component which are capable of generating heat upon contact. The components are selected such that contact of the components is a part of an exothermic process of either a physical or a chemical nature and results in generation of heat. A list of exothermic processes is given and includes dissolution of organic/inorganic salts, oxidation/reduction, hydration of substantially anhydrous compounds and acid/base reactions. In acid-base reactions, the acids, whether organic or inorganic, are preferably strong acids with pKa less than 4, or more preferably less than 2. Preferred organic acids include choloro acetic acid, dichloro acetic acid, acetic acid, oxalic acid, formic acid, lactic acid or mixtures thereof.

US20040173244 (Ecolab, 2004) describes a cleaning process comprising an acid and an alkali treatment step and one or more additional alkaline and/or acid cleaning steps. This process requires at least three steps and is directed towards mechanical cleaning of crockery in commercial dishwashers for removal of starch deposits. Cleaning of fabrics is not taught.

None of the art cited above provides a fatty acid component for uniform and relatively more convenient application to fabric in safe and environment-friendly manner with relatively less wastage. US5262079 (Procter & Gamble, 1993) discloses a neutral pH cleansing bar comprising: at least two phases and a sum total of from about 5% to about 50% of a mixture of free and neutralized monocarboxylic acid; from about 15% to about 65% of an anionic and/or nonionic bar firmness aid; and from about 15% to about 55% water by weight of said bar.

US5312559 (Procter & Gamble, 1993) relates to a stable semi-solid personal cleansing composition comprising: (a) from about 7% to about 33% by weight of potassium C8 -C22 fatty acid soap; (b) from about 4% to about 18% C8 -C22 free fatty acid;

(c) from about 40% to about 70% water; and

(d) from about 5% to about 30% of a polyol selected from the group consisting of: glycerin (glycerol), propylene glycol, polypropylene glycols, polyethylene glycols, ethyl hexanediol, hexylene glycols, and other aliphatic alcohols; and mixtures thereof; and (e) from about 0.5% to about 15% petrolatum emollient, preferably having a weight average particle size of from about 45 microns to about 120 microns.

US5227086A (Procter & Gamble, 1992) provides a firm, low smear, ultra mild, weakly acidic skin pH cleansing bar comprising by weight of said bar: from about 5% to about 50% of essentially free carboxylic acid, preferably myristic acid, behenic acid, or 12- hydroxy stearic acid; from about 15% to about 65% of a water-soluble organic anionic and/or nonionic bar firmness acid, preferably sodium cocoyl isethionate or sodium lauroyl isethionate; and from about 15% to about 55% water. The skin pH bar can contain little or no soap, yet has a shallow penetration value of from zero up to 12 mm.

EP165863 (Unilever, 2007) discloses a melt cast solid cleansing composition free of soap consisting of 15-50% by weight of fatty acid selected from myristic acid, stearic acid, palmitic acid, hydroxy stearic acid, and mixtures thereof; 2-40% by weight non soap detergent active, and 30-60% by weight water and wherein the said composition is free of pure lyotropic liquid crystalline phase in the temperature range 20-100 ⁰ C and forms an isotropic liquid phase or a dispersion of lyotropic liquid crystalline phase in the continuum of isotropic liquid in the temperature range 40-100 ⁰ C. Present inventors have found that a cleaning composition in a shaped solid format comprising fatty acid, binder, surfactant and water in specific proportions solves the aforementioned problems encountered in prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a shaped solid cleaning composition comprising: a. at least 55% by weight fatty acid having melting point greater than 20 0C; b. 2 to 10% by weight a polyhydric alcohol binder; c. 0.1 to 25% by weight water; and d. 0.1 to 20% by weight surfactant.

According to a second aspect of the present invention, there is provided a method of cleaning a substrate comprising, in any order, the steps of: i. applying to the substrate the shaped solid cleaning composition as claimed in any one of the preceding claims 1 -6; and ii. contacting the substrate with an alkaline cleaning medium.

DETAILED DESCRIPTION OF THE INVENTION

Fatty acid

The shaped solid cleaning composition comprises by weight at least 55%, preferably at least 65%, more preferably at least 70% fatty acid. The shaped solid cleaning composition comprises up to preferably 95%, more preferably 85%, and most preferably 80% by weight fatty acid having melting point greater than 20 ⁰ C. Melting point of fatty acid is preferably greater than 30° C, more preferably greater than 4O ⁰ C and most preferably greater than 50 ° C.

The fatty acid may be branched or unbranched. The fatty acid has at least one COOH group and may have other substituted groups such as hydroxyl. Fatty acid may be saturated or unsaturated although saturated fatty acid is preferred. Fatty acid is preferably C8-C22 fatty acid, more preferably C10-C18 fatty acid and most preferably C12-C16 fatty acid. Fatty acids that can be used according to the present invention include lauric acid, myristic acid, palmitic acid, stearic acid, hydroxy stearic acid and behenic acid.

Preferred fatty acids with their corresponding soap having solubility in water at 25 ⁰ C of greater than 2 g/ 100 g water are preferred.

Binder The shaped solid cleaning composition comprises 2 to 10%, preferably 3 to 8 % and more preferably 4 to 7 % by weight polyhydric alcohol binder.

Preferred polyhydric alcohols include glycerol, sorbitol, mannitol, alkylene glycol and polyalkylene glycol.

Polyhydric alcohol binder is preferably selected from alkylene glycol or polyalkylene glycol.

Alkylene glycol is preferably a short chain alkylene glycol, more preferably ethylene glycol or propylene glycol. Polyalkylene glycol is preferably selected from polyethylene glycol or polypropylene glycol. Molecular weight of polyalkylene glycol is preferably from 200 to 20000, more preferably from 200 to 8000 and most preferably from 200 to 5000.

Water

The shaped solid cleaning composition comprises 0.1 to 25%, preferably 5% to 20 % and more preferably 10 to 20% by weight water.

Surfactant The shaped solid cleaning composition comprises 0.1 to 20%, preferably 1 to 15 % and more preferably from 2 to 10% by weight surfactant.

The surfactant may be anionic, nonionic, cationic, zwitterionic or amphoteric. HLB value of surfactant is preferably less than 14, more preferably less than 12, and most preferably less than 10. The term HLB value as used herein means hydrophilic- lipophilic balance. The term HLB is defined in Ansel's pharmaceutical dosage forms and drug delivery systems by Allen et al (published by Lippincott, Williams and Wilkins, 2004) which is incorporated herein by reference. Some of the preferred surfactants and corresponding HLB values are listed below:

Sorbitan mono oleate, commercially available as SPAN® 80 (ICI) - 4.3 Sorbitan mono stearate, commercially available as SPAN® 60 (ICI) - 4.7 Sorbitan mono palmitate, commercially available as SPAN® 40 (ICI) - 6.7 Sorbitan mono laurate, commercially available as SPAN® 20 (ICI) - 8.6 Sorbitan trioleate commercially available as SPAN® 85 (ICI) - 1.8 Sorbitan tristearate commercially available as SPAN® 65 (ICI) - 2.1 Glyceryl monostearate - 3.8 Sodium laurate - 8.6

Carboxylic acid or polvcarboxylic acid

The shaped solid cleaning composition comprises 0.1 to 10%, preferably 1 to 8 % and more preferably 2 to 6% by weight a carboxylic acid or a polycarboxylic acid. The terms "carboxylic acid" or "polycarboxylic acid" as used herein exclude the fatty acid.

The carboxylic acid is preferably water soluble, i.e. it has a solubility of greater than 5 g/ 100 g water at 25 ⁰ C. The polycarboxylic acid is preferably water soluble, i.e. it has a solubility of greater than 2 g/ 100 g water at 25 ⁰ C. (This aspect distinguishes them from fatty acids which have far less solubility)

Examples of carboxylic acid include citric acid, tartaric acid, malic acid, malonic acid, succinic acid, maleic acid, oxalic acid, and fumaric acid .

Preferred polycarboxylic acids include polyacrylic acid, polymethacrylic acid, polymaleic acid, polyacrylic/polymaleic acid co-polymers, and poly amino acid. Non- limiting examples of poly amino acids include poly gamma glutamic acid and polyaspartic acid. Polyacrylic acid is particularly preferred. Preparation of shaped solid cleaning composition

The shaped solid cleaning composition may be prepared by mixing all the ingredients of the composition and heating the mixture above the melting point of the fatty acid to form a pourable mix. The shaped solid cleaning composition may also be prepared by mixing all the ingredients to form a mixture, optionally heating the mixture, and extruding the mixture.

Preferably, fatty acid, binder and surfactant are heated together above the melting point of the fatty acid to form a premix to which water mixed with carboxylic or polycarboxylic acid, if present, and preheated to temperature between 50 to 80 ⁰ C is added and stirred to form a pourable mix. The pourable mix is then poured into mold followed by cooling to temperature less than the melting point of the fatty acid and separating the shaped solid cleaning composition from the mold.

The mold is designed to produce a shaped solid of any geometric shape that is convenient to handle. The shape of shaped solid cleaning composition may be cylindrical, conical, prismatic, pyramidal, frustoconical, or spherical. Preferably the shape is cylindrical. The dimensions of the shaped solid may be chosen by a person skilled in the art such that the shaped solid is easy to handle and convenient to transfer on a substrate by rubbing.

Method of cleaning a substrate

According to an aspect of the present invention, there is provided a method of cleaning a substrate comprising the steps of applying to the substrate a method of cleaning a substrate comprising, in any order, the steps of: i. applying to the substrate a shaped solid cleaning composition comprising: a. at least 55% by weight a fatty acid having melting point greater than 20° C,

b. from 2 to 10% by weight a polyhydhc alcohol binder; c. from 0.1 to 25% by weight water; and d. from 0.1 to 20% by weight surfactant; and ii. contacting the substrate with an alkaline cleaning medium. The process steps may be carried out in any sequence, i.e. applying the shaped solid cleaning composition to the substrate followed by contacting of the substrate with the alkaline cleaning medium or alternatively, contacting the substrate with the alkaline cleaning medium followed by applying the shaped solid cleaning composition to the substrate, although the former sequence is preferred.

It is preferred that the method comprises the steps of applying the shaped solid cleaning composition to the substrate followed by immersing the substrate in the alkaline cleaning medium for 1 to 60 minutes. It is preferred that the substrate is further rinsed with water.

It is preferred that the substrate is wetted with water prior to applying the shaped solid cleaning composition to the substrate.

Preferably, the shaped solid cleaning composition is applied to the substrate by rubbing the shaped solid against the substrate to transfer some amount of solid composition on to the substrate. The amount of shaped solid cleaning composition applied to the substrate is preferably from 0.01 to 25 mg, more preferably from 0.1 to 10 mg and most preferably from 0.1 to 5 mg per cm ² of the substrate area.

The substrate may be a hard surface or a fabric. Hard surface includes plastic, metal, glass and ceramic. The fabric that can be treated includes synthetic as well as natural textiles. Fabric material includes cotton, polycotton, polyester, silk or nylon. It is envisaged that the method of the present invention can be used to treat garments and other clothing and apparel materials that form typical washload in household laundry.

The household materials that can be treated according to the process of the present invention include, but are not limited to, bedspreads, blankets, carpets, curtains and upholstery. Although the process of the present invention is described primarily for treatment of a textile fabric, it is envisaged that the process of the present invention can be advantageously used to treat other materials such as jute, leather, denim and canvass. It is envisaged that the process of the present invention can be used to treat articles such as shoes, rain-wear and jackets. Any shaped solid cleaning composition described earlier may be used in the method of the present invention.

Alkaline cleaning medium Alkaline cleaning medium comprises water and an alkaline ingredient and has pH greater than 7, preferably greater than 8, more preferably greater than 9 and most preferably greater than 9.5.

Alkaline material can be inorganic or organic. Although organic alkaline material such as C1 -C10 amines, C1-C10 alkanolamines and urea may be used, it is preferred that the alkaline material is inorganic. Preferably, inorganic alkaline material is selected from carbonate, bicarbonate, phosphate or hydroxide of an alkali metal, alkaline earth metal or ammonium. Particularly preferred inorganic alkaline material is selected from carbonate, bicarbonate, phosphate or hydroxide of an alkali metal. Amongst alkali metals, sodium is particularly preferred. The most preferred alkaline material is selected from sodium carbonate, sodium thpolyphosphate or mixture thereof.

The alkaline cleaning medium comprises by weight preferably from 0.01 % to 20%, more preferably form 0.1 % to 15 % and most preferably from 2 to 10% of an alkaline ingredient.

Most of the commercially available detergent compositions typically comprise one or more alkaline ingredients and when such detergent compositions are added to water, the resulting mixture may be used as an alkaline cleaning medium.

The invention will be now illustrated with non-limiting examples. The examples are by way of illustration only and do not limit the scope of the invention in any manner.

Examples: Materials

Following materials were used in the experiments. Table 1 : Materials used in the experiments

Preparation of shaped solid cleaning composition (sticks)

Fatty acid, polyhydric alcohol binder, and surfactant were mixed in amounts according to the required composition and heated to 80° C with continuous stirring to prepare molten fatty acid adjunct. Water, along with carboxylic acid and/or polycarboxylic acid, if present, was preheated 70° C and added to molten fatty acid adjunct and stirred vigorously for 10 minutes at 70° C till the mixture was homogeneous. The mixture was transferred to a cylindrical stick mould. The mould with the filled mixture was cooled to about 5 ⁰ C in a refrigerator to solidify the mixture into a stick. The sticks were removed from the mould for further experiments. Cylindrical sticks of diameter of about 2 cm and height of about 8 cm were obtained. Evaluation of stick properties Mechanical Strength

Mechanical strength of the shaped solid cleaning composition was qualitatively determined and rated on a scale from 0 to 2 with higher rating indicating better mechanical properties as given below.

0 - No shape retention of the solid composition or too soft with phase separation

1 - Solid composition retains shape but brittle whilst transferring on fabric

2 - Solid composition retains shape and transfers smoothly on fabric without being brittle

Transferability of the stick on the fabric

Transferability of the stick on Fabric was measured gravimetrically after 15 rubs of the stick on 10x10 cm ² fabric swatches. The stick was applied to fabric in a manner similar to use of chalk on a blackboard. The stick was applied to the fabric by rubbing to transfer solid composition from the stick to the fabric. After applying 15 rubs on the swatch, gravimetric measurements were made and transferability was expressed as mg of the composition transferred per cm2 are of the fabric on the basis of 4 replicates.

Determination of cleaning efficacy

Fabrics

Cotton fabric swatches (size 10 cm x 10 cm, weighing about 1 g) were desized by soaking them overnight in a 3:1 mixture of chloroform and methanol, followed by two hot water washes in 3 g/L of commercially available detergent powder SURF Excel®

(UNILEVER).

Soiling

Triolein (50 ml_) was mixed with 4 mg each of C-soot and Fβ3θ ₄ and the mixture was sonicated in an ultrasonic bath for two and a half hours to prepare a composite soil.

About 300 L of the composite soil was pipetted onto the desized cotton fabric swatch resulting into a stain of about 3 cm diameter. The stained area was dried before the soiled fabric swatch was used for subsequent washing experiment. Cleaning protocol

Experiments were carried out with cotton swatches. Soiled fabric swatches were wetted by sprinkling water and fatty acid stick compositions were transferred onto stained area of fabric swatches by rubbing the stick against the fabric (15 rubs) till the stained area of the fabric is covered with a layer of the solid composition.

Sodium carbonate (1 part) was dissolved in 1000 parts water to prepare alkaline cleaning medium. Fabrics were soaked in an alkaline cleaning medium for about 30 minutes at liquor to cloth ratio of about 50. After soaking, the fabrics were washed in the same alkaline cleaning medium at a liquor to cloth ratio of about 50 by using a tergotometer operating at rpm of about 90 for 15 minutes followed by 3 rinses of 2 minutes each in water.

Reflectance measurements Cleaning efficacy was evaluated by measurement of reflectance using Gretag Macbeth Colour Eye 7000A. Initial reflectance of unsoiled cotton swatch was measured. Reflectance was also measured after soiling (AS) and after washing the soiled fabric (AW). Reflectance measurements were based on 5 replicates.

Effect ;__of various _.. ingredients ; _. and _. thelr_levejsjn _. the _. composltion

Various stick compositions were prepared. The composition details, mechanical strength and lransferabiiity Io fabric are tabulated below along with the cleaning efficacy measured by following the protocol described above.

.Table.2; . Effect, of viiπQ.usj.n.αχe^

From the above tabie, it can be seen that the sticks with composition according to the present invention (Ex No 1 , 2 and 3) have good mechanicai strength and good transfer characteristics on fabric, and when used for cieaning according to the process of the present invention, provide good cleaning efficacy whilst the stick compositions outside the scope of the present invention (Comparative Ex A, B and C) lack mechanical strength and can not be easily appiied to fabric.

Cleaning efficacy of the method of cleaning

Composition of Comparative Example D was identical to the composition of Example

1 in all respects except that it comprises 70% sodium laurate instead of lauric acid.

Table 3: Cleaning efficacy of the method of cleaning

Cleaning was carried out using a method identical to that of Example 1 . However composition of Comparative Ex No D resulted into formation of solid lump and could not be molded and was difficult to transfer on fabric. Cleaning efficiency was measured where the composition of Comparative Ex No D was added to the aqueous cleaning medium. It can be seen that cleaning method of present invention (Ex 1 ) provided better cleaning efficacy as compared with cleaning with soap composition (Comparative Example D).

5 Examples 4 and E were similar to Example 1 in all respects except in the type of fatty acid used. The composition details along wilh specific fatly used and its melting point, mechanical strength, transferabillty to fabric and cleaning efficacy are tabulated below. Details of Ex 1 are retabulated for convenience.

i o Tabje. A;..ifiβct of Mej|ing.p.gintMMty..gcid

It is clear from the table that stick composition comprising fatty acid having melting point greater than 20° C (Ex 1 and Ex 4) have better mechanical properties as compared to stick composition comprising fatty acid having melting point less than 15 20° C (Comparative Ex E).

Effect of HLB value of surfactant

Following examples are identical to Ex 1 in all respects except for the surfactant used. Surfactants used along with their respective HLB values are tabulated below along 20 with mechanical properties, transferability and cleaning efficacy.

Table 5: Effect of HLB value of surfactant

Ex No Surfactant HLB Mechanical Transfer on Cleaning strength fabric Efficacy { R) (mg/cm2)

5 Span-SO® (IC!) 4.3 2 1.1 29

8 Sodium laurate 8.6 2 1.1 29 From the results, it is clear that the stick composition comprising surfactant with HLB values less than 14 (Examples 1 , 5 and 6) result into sticks with acceptable mechanical strength.

Illustration of various binders

Following examples are identical to Ex 1 in all respects except for the binder used in the stick compositions.

Table 6: Illustration of various binders

The results above illustrate various polyhydric alcohols and mixtures thereof that can be used as binder in the stick composition in order to provide acceptable mechanical properties.

Effect of carboxylic acid/polvcarboxylic acid

Following examples are identical to Ex 1 in all respects except that stick compositions comprised 65% by weight of fatty acid instead of 70% by weight fatty acid. Instead, the compositions comprised 5% by weight of a carboxylic acid or polycarboxylic acid according to details tabulated below.

Table ^" T: Effect of carboxvlic acid/polvcarboxvlic acid

Ex Carboxylic Acid Mechanical Transfer on Cleaning

No strength fabric Efficacy ( R) (rng/cm ² )

10 Citric Acid 2 1.1 32

11 Tartaric Acid 2 1.1 32

12 Polyacryiic acid 2 1.1 33

(molecular weight 1800)

The results indicate that incorporation of carboxylic acid in the stick composition results into further improvement in the cleaning efficacy. It will be appreciated that the illustrated examples demonstrate that the shaped solid cleaning composition according to the present invention has good mechanical properties and transferability to substrate which allows uniform and relatively more convenient application to the substrate in safe and environment-friendly manner with relatively less wastage. Furthermore, the method of cleaning a substrate according to the present invention is convenient and provides good cleaning efficacy.