Title of Invention

A THICKENED BLEACH COMPOSITION

Abstract

The present invention relates to thickened cleaning compositions that comprise a bleaching agent for cleaning hard surfaces. The invention relates to athickened bleach composition comprising water, hypochlorite bleaching agent and surfactant characterised in that it comprises: 0.1 - 10% of a hypochlorite salt; 0.5 -20% of a surfactant; 0.1-8% of an electrolyte selected from the group consisting of alkali metal hydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the composition comprises at least two different kinds fo alkli metal ions.

Full Text

FORM -2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10) TECHNICAL FIELD FORM -2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See Section 10) A THEKENED BLEACH COMPOSITION HINDUSTAN LEVER LIMITED, a company incorporated under the Indian Companies Act, 1913 and having its registered office at Hindustan Lever House, 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India 17 NOV 2004 The following specification particularly describes the nature of the invention and the manner in which it is to be performed. TECHNICAL FIELD The present invention relates to thickened cleaning compositions that comprise a bleaching agent for cleaning hard surfaces. The present invention particularly refers to cleaning compositions having bleaching agents that have surfactants which are widely and easily available and which can be thickened using inexpensive additives. BACKGROUND AND PRIOR ART Hard surfaces are encountered in most aspect of everyday life. These include surfaces in both non-industrial establishments like homes and offices and industrial establishments like factories. Hard surfaces in homes include floors, walls, ceilings, furnitures, kitchen utensils and cookware. Hard surfaces in offices and factories also include floors, walls, ceilings, furniture, equipments and instruments. Typically the hard surface constitutes ceramic, metals (e.g. stainless steel), stone, wood, vitreous enamel and chrome plated surfaces. Cleaning hard surfaces in all these variety of surfaces have been achieved using a variety of methods including physical methods like abrasion, chemical methods like use of surface active agents, solvents, bleaches, acids and alkalies and various combinations of the above methods. Surfactants are commonly used in most cleaning compositions for cleaning such surfaces. The compositions for cleaning hard surfaces are usually in the form of liquids, liquid abrasive cleaners, gels, pastes, powders or bars. 2 Cleaning compositions comprising bleaches have also been quite popular and useful in cleaning especially difficult-to-remove stains. Generally, the beaching action is as a result of the oxidative properties of free chlorine or oxygen that are liberated from the bleach compounds. To enhance cleaning, in addition to the bleaching action, many cleaning compositions include surface active agents like soaps and detergents in these bleach compositions. There has often been a need to thicken cleaning compositions comprising bleaches. Such thickened compositions are easier to dispense. Also, one desires that when these compositions are applied on to surfaces to be cleaned, the compositions are in contact with the surface for sufficiently long time to enable good cleaning action. This is especially significant when the compositions are applied underneath horizontal surfaces or to vertical or inclined surfaces. There have been many reported methods to thicken bleach compositions. The methods to thicken these compositions include use of polymers or by incorporating detergent actives in high quantities both of which are expensive options. US4839077 (1989, The Clorox Co.) describes a thickened bleach composition comprising (i) a bleaching halogen compound, (ii) a polymeric thickener having a molecular weight of one thousand to hundred thousand comprising a charged monomer and an uncharged monomer, such that the resulting polymer has a acid number between 80 to 400 mg KOH/g polymer and (iii) a surfactant system including a bleach resistant uncharged surfactant and a bleach-resistant anionic surfactant. 3 US5821214 (1998, Reckitt and Colman Inc.) describes a cleaning composition comprising (i) from 0.5 to 10% of soft abrasive particles (ii) from 0.5 to 2.5% of a chlorine containing bleach, (iii) from 0.2 to 3% of a thickening system comprising a crosslinked polyacrylate resin having a molecular weight in the range of I million to 10 million (iv) from 0.25 to 3% of a bleach stable surfactant system comprising mainly anionic surfactants and (v) sufficient amount of potassium or sodium hydroxide to provide a pH in the range of 11.5 to 13. 5. JP10251687 (1998, Kao Co. Ltd.) describes a liquid bleach composition for hard surface cleaning that comprises (i) 0.1 to 8% of alkali metal hypochlorite salt (ii) 0.1 to 9% of alkali metal hydroxide (iii\ Q.t to 5% of anionic surfactant and (iv), 0-1 to 5% of a buffer which is preferably phosphoric acid or its salts or soluble silicic acid salts. US6100228 (2000, The Clorox Co.) describes a bleaching gel cleaner and a method of preparing it comprising (i) an effective amount of a hypochlorite generating compound (ii) a ternary thickening system comprising (a) alkali metal soap; (b) a hydrotope consisting of trialkylamine oxides, betaines and mixtures thereof; and (iii) bleach stable solvent, and (iv) a buffer/electrolyte to stabilize the composition, the balance being water. The prior arts cited above teach methods to thicken bleach compositions utilizing compounds like polymers e.g. polyacrylates, non-ionic surfactants like amine oxides, soaps or a combination of the above. These compounds are expensive and it is desirable to develop methods to thicken bleach compositions using more easily and inexpensively available compounds and materials. 4 OBJECTS OF THE INVENTION It is thus an object of the invention to provide for a bleach composition that is thick and has a desired viscosity that it can be applied on a wide range of surfaces. It is a further object of the invention to provide for a bleach composition that is thickened using materials that are inexpensive and easily available. SUMMARY OF THE INVENTION A thickened liquid bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises 0.1-10%w of a hypochlorite salt, chosen from sodium and potassium hyypochlorite; 0.5 - 20%w of a surfactant; 0.1- 8%w of an electrolyte selected from the group consisting of alkali metal hydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the composition comprises at least two different kinds of alkali metal ions, the least prevalent alkali metal ion in the composition being present in a molar amount of at least 10% of the total alkali metal ion content, and wherein polymeric thickening agents are absent in the composition; and the total cation content of the composition consisting entirely of alkali metal cations.. According to a preferred aspect of the invention, there is provided a synergistic thickened bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises ; 0.1 -10% w of a surfactant 0.5 -20%o w of a surfactant 0.1- 8%> w of an electrolyte selected from the group consisting of alkali metalhydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the cation of at least one electrolyte is different from cation of the hypochlorite salt. 5 It is particularly preferred that the electrolytes are so chosen that the pH of the composition is at least 11. It is desirable that the least prevalent alkali metal ion in the composition is present in a molar amount of at least 10% of total alkali metal ions. DETAILED DESCRIPTION OF THE INVENTION All parts herein are by weight unless otherwise specified. The thickened bleach composition as per the invention essentially comprises one or more hypochlorite salts, one or more surfactants compatible with the bleaching agent and one or more electrolytes, along with water. Bleaching agent: The bleaching agent as per this invention is a hypochlorite salt. The hypochlorite salt is preferably an alkali metal hypochlorites. The alkali metal is chosen from sodium, potassium or lithium, more preferably sodium or potassium. Many commercially available solutions of alkali metal hypochlorites in water also include the alkali metal salt. This is due to the method of manufacture of alkali metal hypochlorites which constitutes reacting alkali metal hydroxides with chlorine gas to form the corresponding alkali metal hypochlorites and the alkali metal salts. These are often sold as such without further purification and are often called "high salt" bleach. E.g. if the alkali metal is sodium, the "high salt" sodium hypochlorite bleach solution also contains sodium chloride. It is also possible to source alkali metal hypochlorites which are free of the corresponding salt. Such products, often termed low salt" or "high purity" bleaches are prepared by reaction 6 of alkali metal hydroxide with hypochlorous acid. It is possible to prepare the thickened bleach composition of the present invention starting with1 either of the so called "high salt" or "low-salt" bleaches. A particularly preferred bleaching agent of the present invention is sodium hypochlorite due to its wide availability and I It is also preferred that the "high salt" form of the commercially available sodiuni hypochlorite bleach solution be used in the present invention as it is more widely and cheaply available compared to the corresponding "low-salt" solutions. The thickened bleach composition as per the invention comprises bleaching agent from 0.1 to 10%, preferably from 0.1 to 8 %, and most preferably 0.1 to 5% by weight of the composition. Surfactant: A surfactant compatible with the bleaching agent is used in the thickened bleach composition of the present invention. The surfactant is a soap or a non-soap, surfactant, it is more preferred that the active is a non-soap surfactant. Further, the composition according to the invention preferably comprises detergent actives which are chosen from anionic, non-ionic, cationic, amphoteric or ^witterionic detergent actives. It is particularly preferred to use anionic surfactants for the invention, and the anionic surfactants may have an alkali or alkaline earth metal or ammonium or alkanolamine counter ion of or a mixture thereof. The preferred water-soluble synthetic anionic surface active compounds are the alkali metal (such as sodium and potassium) salts of higher alkyl benzene sulphonates; sodium alkyl glyceryl ether sulphates, especailly those ethers of the higher alcohols 7 derived from coconut oil and tallow; primary and secondary alkyl sulphonates (PAS and SAS); olefin sulphonates; and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates and mixtures thereof. The preferred anionic surfactant are water-soluble salts of organic sulphuric acid mono-esters and sulphonic acids having in the molecular structure a branched or straight chain alkyl group containing 8-22 C atoms or an aryl or alkylaryl group containing 8-22 C atoms. Particularly preferred anionic surface active compounds for use in the present invention is SLES (sodium lauryl ether sulphate - ethoxylate derivative) and primary and secondary alkyl sulphonates. It is also possible to include nonionic, cationic, amphoteric, or zwitterionic detergent actives in the compositions according to the invention The detergent actives used in the detergent composition of the invention could also be chosen from the detergent active compounds given in the well-known textbooks "Surface Active Agents", Volume I by Schwartz and Perry and "Surface Active Agents and Detergents", Volume II by Schwartz, Perry and Berch. The thickened bleach composition as per the invention comprises one or more surfactants compatible with the bleaching agent and is incorporated from 0.5 to 20% by weight of the composition, preferably from 0.5 to 10 % by weight of the composition. 8 Electrolytes Electroytes used in the thickened bleach composition are chosen from the group comprising alkali metal hydroxides, halides, sulphates carbonates or mixtures thereof. The preferred alkali metal cation is sodium or potassium. Preferred electrolytes include alkali metal hydroxides, chlorides, sulphates and mixtures thereof. It is preferred that the cation of at least one electrolyte is different from the cation of one of the alkali metal hypochlorite, e.g. when the alkali metal hypochlorite is sodium hypochlorite, then one of the electrolyte could be potassium hydroxide, potassium chloride, lithium hydroxide and the like. It is preferred that the mole percent of the cation of the electrolyte that is different from the cation of the alkali metal hypochlorite is at least 10% of the total moles of cations of the electrolytes and cations of the alkali metai hypochlorita E.g. when the bleaching agent is sodium hypochlorite and the electrolytes used are potassium chloride and potassium hydroxide then it is preferred that the mole percent of potassium ion from potassium chloride and potassium hydroxide is at least 10 mole percent of the total moles of potassium and sodium present in the system from the electrolytes and the bleaching agent. It is also preferred that the electrolytes are so chosen to ensure that the pH of the thickened bleach composition is at least 11 and more preferred that it is at least 12.5. It is also possible that when "high-salt" alkali metal hypochlorites are used, there is some amount of electrolyte in the form of the corresponding alkali metal chloride present in the composition. The electrolytes are present in the range of 0.1 to 8%, more preferably in the range of 0.1 to 5.0 % by weight of the composition. 9 In addition to the desired concentration of the bleaching agent, the surfactant and the electrolyte, the composition comprises water. Optional ingredients The composition according to the invention may contain other ingredients that aid in their cleaning and other performance and perception led benefits. For example, solvents, abrasives, structurants, colourants, hydrotropes, whiteners, optical brighteners, soil suspending agents, preservatives and perfumes. The bleach composition of the invention can be in the form of a pourable liquid, thick liquid, gel, paste, or mousse. A preferred form is a thick liquid or a gel. The invention is now illustrated by the following non-limiting examples. EXAMPLES Comparative Examples: Where the cation of the alkali metal hypochlorite and the cation of the electrolytes are the same Comparative Example A 280 grams of sodium lauryl ether sulphate -ethoxylate derivative (SLES) 2.5 EO was taken in a 3 liter vessel. To this was added a pre-prepared solution of 134 grams of sodium hydroxide, 2 grams of sodium silicate solution (50% solids), and 10 grams of sodium chloride, dissolved in 1580 grams of water with continuous stirring. 140 grams of a "high-salt" sodium hypochlorite solution (containing 30 grams sodium hypochlorite and 26 grams sodium chloride and the balance water) was added to the above mixture with constant stirring to prepare a bleach composition. Comparative Example B A composition as per Comparative Example A was prepared except that 16 grams of sodium chloride was used instead of the 10 grams of sodium chloride in the pre-prepared solution. Comparative Example-C A composition as per Comparative Example A was prepared except that 20 grams of sodium chloride was used instead of the 10 grams of sodium chloride in the pre-prepared solution. Examples: As per the invention wherein the cation of at least one electrolyte is different from the cation of the alkali metal hypochlorite Example-1 A composition as per Comparative Example -A was prepared except that 10 grams of potassium chloride was added instead of sodium chloride Example-2 A composition as per Comparative Example -B was prepared except that 16 grams of potassium chloride was added instead of sodium chloride Example-3 A composition as per Comparative Example -C was prepared except that 20 grams of potassium chloride was added instead of sodium chloride Table 1 lists the compositions as per comparative examples A,B,C and Examples 1,2,3 along with the weight percent of the ingredients. Table 1 also lists the viscosities of the compositions. Table-1 Ingredients Comp Ex. A Ex1 Comp Ex. B Ex 2 Comp Ex. C Ex 3 Sodium hypochlorite 1.5 1.5 1.5 1.5 1.5 1.5 SLES 3 3 3 3 3 3 NaOH 0.67 0.67 0.67 0.67 0.67 0.67 KOH - - - - - - Sodium silicate 0.05 0.05 0.05 0.05 0.05 0.05 NaCI 1.8 1.3 2.1 1.3 2.3 1.3 KCI - 0.5 - 0.8 - 1.0 DM water to 100 100 100 100 100 100 Total electrolyte 2.47 2.47 2.77 2.77 3.07 3.07 Mole% K 0 14.5 0 21.4 0 25.4 Viscosity, cps 18 45 34 113 62 460 The data in Table -1 indicates that for the same total electrolyte concentration, when cation of an electrolyte is different from the cation of the bleaching agent, there is synergistic benefit in terms of viscosity of the composition. Comparative Examples: where a mixture of surfactants were used and the cation of the electrolyte was the same as the cation of the alkali metal hypochlorite Comparative Example-D A composition was prepared as per Comparative Example B except that 187 grams of SLES and 93 grams of secondary alkyl sulphate was used instead of 280 grams of SLES. Comparative Example-E A composition was prepared as per Comparative Example C except that 187 grams of SLES and 93 grams of secondary alkyl sulphate was used instead of 280 grams of SLES. Examples: where a mixture of surfactants were used and the cation of at least one of the electrolytes was different from the cation of the alkali metal hypochlorite. 12 Example-4 A composition was prepared as per Example 2 except that 187 grams of SLES and 93 grams of secondary alkyl sulphate was used instead of 280 grams of SLES. Example-5 A composition was prepared as per Example 3 except that 187 grams of SLES and 93 grams of secondary alkyl sulphate was used instead of 280 grams of SLES. Table 2 lists the compositions as per comparative examples D and E and Examples 4 and 5 along with the weight percent of the ingredients. Table 2 also lists the viscosities of the compositions. Table-2 Ingredients Comp Ex. D Ex 4 Comp Ex. E Ex 5 Sodium hypochlorite 1.5 1.5 1.5 1.5 SLES 2 2 2 2 SAS 1 1 1 1 NaOH 0.67 0.67 0.67 0.67 Sodium silicate 0.05 0.05 0.05 0.05 NaCI 2.1 1.3 2.3 1.3 KCI - 0.8 - 1.0 DM water to 100 100 100 100 Total electrolyte 2.77 2.77 3.07 3.07 Mole% K 0 21.4 0 25.4 Viscosity, cps 27 51 59 117 The data in Table -2 indicates that synergistic benefit in terms of viscosity is also valid when mixtures of surfactants are used. Examples where thickened bleach compositions were obtained over a wide range of concentrations of bleaching agent, surfactants, and electrolytes as per the invention Several thickened bleach compositions were prepared as per the invention over a wide range of concentrations of the various ingredients and the results are shown in Table-3. Table-3 Ingredients Ex-6 Ex 7 Ex. 8 Ex 9 Ex 10 Ex. 11 Sodium hypochlorite 4.5 4.5 3.0 3.0 1.5 1.5 SLES 4.2 5.0 1.5 3.0 3 3 NaOH 0.7 0.7 0.7 0.7 0.15 0.15 KOH - - - - 0.65 0.85 Sodium silicate 0.05 0.05 0.05 0.05 0.05 0.05 NaCI 3.9 3.9 2.6 2.6 1.3 1.3 KCI 0.5 0.5 1.0 1.0 1.0 1.0 DM water to 100 100 100 100 100 100 Total electrolyte 5.1 5.1 4.3 4.3 3.1 3.3 Mole% K 14.3 14.3 25.0 25.0 48.7 52.0 Viscosity, cps 160 280 90 280 296 392 The data in Table-3 indicates that thickened bleach compositions (with viscosities generally higher then 90 cps) can be obtained over a wide range of concentrations of bleaching agent, surfactants and electrolytes by employing the present invention. WE CLAIM 1. A thickened liquid bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises 0.1 -10% w of a hypochlorite salt, chosen from sodium and potassium hypochlorite; 0.5 - 20%w of a surfactant; 0.1 - 8% of an electrolyte selected from the group consisting of alkali metal hydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the composition comprises at least two different kinds of alkali metal ions, the least prevalent alkali metal ion in the composition being present in a molar amount of at least 10% of the total alkali metal ion content, and wherein polymeric thickening agents are absent in the composition; and the total cation content of the composition consisting entirely of alkali metal cations.. 2. A composition as claimed in claim 1 wherein the hypochlorite salt is sodium hypochlorite. 3. A composition as claimed in claims 1 to 2 wherein the surfactant comprises anionic surfactant chosen from water-soluble salts of organic sulphuric acid monoesters and sulphonic acids having in the molecular structure a branched or straight chain alkyl group containing 8-22C atoms or an aryl or alkylaryl group containing 8-22C atoms. 4. A composition as claimed in claims 1 to 3 wherein the electrolyte is chosen from alkali metal hydroxides, chlorides, sulphates and mixtures thereof. 5. A composition as claimed in claim 4 wherein the electrolyte are chosen from sodium and potassium compounds 15 OBJECTS OF THE INVENTION It is thus an object of the invention to provide for a bleach composition that is thick and has a desired viscosity that it can be applied on a wide range of surfaces. It is a further object of the invention to provide for a bleach composition that is thickened using materials that are inexpensive and easily available. SUMMARY OF THE INVENTION A thickened liquid bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises 0.1-l0%w of a hypochlorite salt, chosen from sodium and potassium hyypochlorite; 0.5 - 20%w of a surfactant; 0.1- 8%w of an electrolyte selected from the group consisting of alkali metal hydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the composition comprises at least two different kinds of alkali metal ions, the least prevalent alkali metal ion in the composition being present in a molar amount of at least 10% of the total alkali metal ion content, and wherein polymeric thickening agents are absent in the composition; and the total cation content of the composition consisting entirely of alkali metal cations.. According to a preferred aspect of the invention, there is provided a synergistic thickened bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises ; 0.1 -10% w of a surfactant 0.5 -20% w of a surfactant 0.1- 8% w of an electrolyte selected from the group consisting of alkali metalhydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the cation of at least one electrolyte is different from cation of the hypochlorite salt. 5 WE CLAIM 1. A thickened liquid bleach composition comprising water, hypochlorite bleaching agent and surfactant characterized in that it comprises 0.1 -10% w of a hypochlorite salt, chosen from sodium and potassium hypochlorite; 0.5 - 20%w of a surfactant; 0.1 - 8% of an electrolyte selected from the group consisting of alkali metal hydroxides, halides, sulphates, carbonates and mixtures thereof; and wherein the composition comprises at least two different kinds of alkali metal ions, the least prevalent alkali metal ion in the composition being present in a molar amount of at least 10% of the total alkali metal ion content, and wherein polymeric thickening agents are absent in the composition; and the total cation content of the composition consisting entirely of alkali metal cations.. 2. A composition as claimed in claim 1 wherein the hypochlorite salt is sodium hypochlorite. 3. A composition as claimed in claims 1 to 2 wherein the surfactant comprises anionic surfactant chosen from water-soluble salts of organic sulphuric acid monoesters and sulphonic acids having in the molecular structure a branched or straight chain alkyl group containing 8-22C atoms or an aryl or alkylaryl group containing 8-22C atoms. 4. A composition as claimed in claims 1 to 3 wherein the electrolyte is chosen from alkali metal hydroxides, chlorides, sulphates and mixtures thereof. 5. A composition as claimed in claim 4 wherein the electrolyte are chosen from sodium and potassium compounds. 15

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