IMPROVEMENTS RELATING TO BLEACHING COMPOSITIONS

Abstract: The invention relates to an aqueous bleaching composition of pH 1-3 which comprises: a) 0.1-15 % wt surfactant; b) 3-15 % wt hydrogen peroxide or a source thereof; c) 0.5-10 % wt disodium dihydrogen pyrophosphate; d) 0.1-1 % wt of at least one metal ion complexing agent other than (c); and e) 0.01-1 % wt perfume. The invention also provides a process for removing stains from textile articles which comprises the step of treating the articles with a composition as described above.

Description: IMPROVEMENTS RELATING TO BLEACHING COMPOSITIONS Technical Field The present invention relates to bleaching compositions, and relates particularly to bleaching compositions which can be used on fabrics either by direct application of the composition to the fabric or as a wash additive Background to the invention In household cleaning, fabric washing and in many other areas there is a general need for agents which can 'bleach' unsightly materials, i.e. which can react with these materials to decolourise them. One of the commonest of such bleaching agents is sodium hypochlorite, which is widely used in cleaning compositions to decolourise soils, to assist in cleaning through its reaction with soils and to kill micro-organisms. Sodium hypochlorite is a powerful oxidising agent, which can decolourise a very large number of coloured compounds found in soils but which has significant limitations. Many consumers prefer not to use chlorine-based bleach compounds due the characteristic and pungent smell of chlorine. There is a need for an alternative to chlorine-based bleaching and bleaching and/or cleaning agents. One well known class of alternatives are the peroxygen compounds. Wash additives based on hydrogen peroxide and other peroxides for laundry applications are well known These generally comprise a surfactant, a peroxygen bleaching agent and a metal sequestering agent. WO 9314183 (P&G: 1992) relates to a stable colourless detergent composition of pH 4-11 which comprises: a) 5-95%wt of anionic or nonionic surfactant (which can be a nonionic surfactant) , b) 0.005-10%wt of an oxygen bleach (which can be hydrogen peroxide) , c) 0.001-8% of a metal sequestering agent (which can be sodium pyrophosphate or a DEQUEST(TM) type sequestering agent) . Brj-ef Peggrjptjpn of the Invention We have determined that stable low pH peroxygen bleaching compositions of pH less than 4 can be formulated using disodium dihydrogen pyrophosphate in combination with a second metal-ion complexing agent. Accordingly, the present invention provides an aqueous bleaching composition of pH 1-3 which comprises: a) 0.1-15%wt surfactant b) 3-15%wt hydrogen peroxide or a source thereof, c) 0.5-10%wt disodium dihydrogen pyrophosphate, d) 0.1-3%wt of at least one metal ion complexing agent other than (c) , and, e; optionally, 0.01-l%wt perfume. The invention also provides a process for removing stains from textile articles which comprises the step of treating the articles with a composition as described herein. Detailed Description of the Invention Compositions according to the present invention invariably comprise at least 0.5%wt of disodium dihydrogen pyrophosphate (otherwise known as sodium acid pyrophosphate) and have a pH in the range 1-3. The other components present are subject to some variability as to their precise nature and are discussed in further detail below. Surfactants Preferred compositions according to the present invention comprise 2-8%wt of surfactant on product. A broad range of surfactants and surfactant combinations can be used in the compositions of the invention. Surfactants can be nonionic, anionic, cationic, amphoteric or zwitterionic provided that they, and where appropriate their counter- ions, do not react substantially with any peroxide compounds present. Preferred surfactants are selected from nonionic surfactants, anionic surfactants and mixtures thereof . Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophillic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophillic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophillic and hydrophobic elements. Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 10 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 2 to 10 moles of ethylene oxide per mole of alkylphenol. The preferred alkoxylated alcohol nonionic surfactants are ethoxylated alcohols having a chain length of C12-C15 and an EO value of at least 2 but less than 10. Particularly preferred nonionic surfactants include the condensation products of Cj , alcohols with 3-9 moles of ethylene oxide. An example of a suitable surfactant is ' Dobanol 25 7EO' (TM, ex. Shell) a Cj , alcohol with seven moles of ethoxy1atIon. When present, the amount of nonionic detergent active to be employed in the composition of the invention will generally be from 0.1 to 15%wt, preferably from 0.1 to 10%wt, and most preferably from 4 to 10%wt . We have also found it useful to employ a mixed nonionic surfactant system which comprises two nomonics one of which has a relatively high HLB and the other of which has a relatively low HLB. In aqueous systems this combination of noniomcs forms a stable emulsion. An example of a suitable system is one which comprises 2-5%wt each of two C12-C15 alcohols ethoxylated with 2-4 and 6-8 moles of ethylene oxide respectively. Two suitable noniomcs are Dobanol 25 7E0 [TM] ex. Shell and Dobanol 25 3E0 [TM] ex. Shell. Alternative surfactants include amine oxides, amines and/or ethoxylates thereof. Amine oxides with a carbon chain length of C12-C14 are particularly preferred. Suitable anionic detergent active compounds are water- soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphur acid ester radicals and mixtures thereof. Examples of suitable anionic detergents are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and potassium alkyl benzene sulphonates such as those m which the alkyl group contains from 9 to 15 carbon atoms; sodium and potassium secondary alkanesulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof . The preferred water-soluble synthetic anionic detergent active compounds are the alkali metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates and mixtures with olefmsulphonates and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates. The most preferred anionic detergent active compounds are higher alkyl aromatic sulphonates (LAS) such as higher alkyl benzene sulphonates containing from 6 to 20 carbon atoms in the alkyl group in a straight or branched chain, particular examples of which are sodium salts of higher alkyl benzene sulphonates or of higher-alkyl toluene, xylene or phenol sulphonates, alkyl naphthalene sulphonates, ammonium diamyl naphthalene sulphonate, and sodium dmonyl naphthalene sulphonate. The most preferred anionics also include the higher alcohol sulphates (also known as alkyl sulphates) containing from 6 to 20 carbon atoms in the alkyl group m a straight or branched chain, particular examples of which are sodium salts of higher primary alkyl sulphates (PAS) . The amount of synthetic anionic detergent active to be employed in the detergent composition of this invention will generally be from 0.1 to 15%, preferably from 1 to 5%wt, with levels of l-2%wt being particularly preferred. Preferably, the compositions contain an amount of both the anionic and the nonionic detergent active. Preferably the total surfactant content lies in the range 0.1-10%wt. The weight ratio of anionic detergent to nonionic detergent active may vary and will depend on their nature but is preferably in the range of from 1:9 to 9:1, ideally from 1 : 4 to 4 : 1. We have determined that a particularly suitable surfactant system comprises 1-2% alkyl benzene sulphonate and 0.5-2%wt C12-15, 5-8 EO ethoxylated alcohol nonionic, a suitable alternative surfactant system 8785 PC17EP97/03059 comprises l-2%wt of primary alcohol sulphate (also known as primary alkyl sulphate) and 0.5-2%wt C12-15, 5-8 EO ethoxylated alcohol nonionic. Perpyj,fle Suitable peroxy compounds for inclusion in compositions according to the invention include, hydrogen peroxide, perborates, persulphates, peroxysulphates, perphosphates, periodates, percarbonates and mixtures thereof. Particularly preferred materials are hydrogen peroxide, sodium peroxide, peracetic acid, performic acid and mono- persulphate salts. Hydrogen peroxide is most preferred. Preferred compositions according to the present invention comprise 5-10%wt hydrogen peroxide, Metal ion complexing aσents Preferred compositions according to the present invention comprise l-7%wt, more preferably l-2%wt disodium dihydrogen pyrophosphate. This material is otherwise known as sodium acid pyrophosphate. Preferred compositions according to the present invention comprise 0.1-0.5%wt of at least one metal ion complexing agent other than disodium dihydrogen pyrophosphate, Preferably, cleaning and/or disinfecting compositions according to the invention will further comprise metal ion sequestrants such as ethylene-diamine-tetra-acetates, amino-polyphosphonates (such as those in the DEQUEST (TM) range) and phosphates and a wide variety of other poly- functional organic acids and salts, can also optionally be employed. Preferred metal ion sequesterants are selected from dipicolinic acid, ethylene diamine tetra acetic acid (EDTA) and its salts, hydroxy-ethylidene diphosphonic acid (Dequest 2010, RTM), ethylene diamine tetra (methylene phosphonic acid) (Dequest 2040, RTM), diethylene triamine penta (methylene phosphonic acid) (Dequest 2060, RTM), amino tri (methylene phosphonic acid) (Dequest 2000, RTM) . The phosphonic acid derivatives are particularly preferred. Diethylene triamine penta (methylene phosphonic acid) (Dequest 2060, RTM) is particularly preferred. It is preferred that the level of phosphonic acid derivative metal ion complexing agent should fall into the range 0.1-3%wt, with levels of 0.1-0.5%wt being particularly preferred. Perfumes Perfume is an optional component of the present invention but is highly preferred. Preferred compositions according to the present invention comprise 0.1-0.2%wt of perfume. A wide range of perfumes can be employed provided that the perfume is sufficiently stable in the composition. Other Minors Where compositions according to the present invention are liquids, they can be water-thin or thickened. Thickened compositions are advantageous in that they cling to sloping surfaces and find particular utility in toilet cleaners. Slight thickening of the composition is desirable for applications in which the composition is sprayed, so as to reduce the extent to which small droplets are produced which might otherwise cause respiratory irritation to the user. Suitable thickening agents include amine oxide and soap and systems based on nonionic surfactants. Preferably the compositions are no significantly thickened. Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients such as, colourants, optical brighteners, soil suspending agents, gel-control agents, freeze-thaw stabilisers and opacifiers. Preferably the pH of compositions according to the invention is in the range 1.5-2.5. The pH of compositions according to the invention can be regulated using acids, preferably HC1 and alkali's, preferably NaOH. In order that the invention can be further understood it will be described hereafter with reference to the following non-limiting examples. Eχapιpτ.es The following compositions (as shown in table 2) were made up using materials as identified in table 1. Table 1 The compositions were prepared by mixing the compounds as indicating below in a stirring tank at room temperature.. No particular order of addition is required, although it is preferred that the perfume and any dyestuff are added last. Table 2 All were found to be stable compositions which showed acceptable bleaching behaviour when used as wash additives and in direct application to soiled articles.

Claims: Claims 1. An aqueous bleaching composition of pH 1-3 which comprises : a) 0.1-15%wt surfactant b) 3-15%wt hydrogen peroxide or a source thereof, c) 0.5-10%wt disodium dihydrogen pyrophosphate, d) 0.1-3%wt of at least one metal ion complexing agent other than (c) , and, e) optionally, 0.01-l%wt perfume. 2. Composition according to claim 1 which comprises 2- 5%wt of each of two C12-C15 alcohols ethoxylated with 2-4 and 6-8 moles of ethylene oxide respectively. 3. Composition according to claim 1 which comprises a surfactant selected from the group comprising alkyl benzene sulphonate containing from 6 to 20 carbon atoms in the alkyl group in a straight or branched chain and alkyl sulphates containing from 6 to 20 carbon atoms in the alkyl group in a straight or branched chain. 4. Composition according to claim 1 wherein the amount of synthetic anionic detergent active in the composition is from l-2%wt . 5. Composition according to any preceding claim which comprises both anionic and nonionic detergent active. 6. Composition according to any preceding claim wherein the at least one metal ion complexing agent other than disodium dihydrogen pyrophosphate is selected from the group comprising: ethylene diamine tetra acetic acid and its salts, hydroxy-ethylidene diphosphonic acid, ethylene diamine tetra (methylene phosphonic acid) , diethylene triamine penta (methylene phosphonic acid), and, amino tri (methylene phosphonic acid) . 7, Composition according to any preceding claim wherein the at least one metal ion complexing agent other than disodium dihydrogen pyrophosphate is a phosphonic acid derivative and the level of phosphonic acid derivative metal ion complexing agent falls into the range 0.1- 0.5%wt. 8. Composition according to any preceding claim wherein the pH of compositions is in the range 1.5-2.5. 9. Composition according to any preceding claim which comprises hydrogen peroxide. 10. A process for removing stains from textile articles which comprises the step of treating the articles with a composition according to any one of claims 1-9 either in neat or dilute form.

Inventors: CROPPER JAMES DAWSON, LUPPI EDUARDO JUNIOR, MARQUEZANO DE MEDEIROS ANA CLA, CROPPER, JAMES, DAWSON, LUPPI, EDUARDO, JUNIOR, MARQUEZANO DE MEDEIROS, ANA, CLAUDIA
Applicants: CROPPER JAMES DAWSON, LUPPI EDUARDO JUNIOR, MARQUEZANO DE MEDEIROS ANA CLA, UNILEVER NV, UNILEVER PLC, CROPPER, JAMES, DAWSON, LUPPI, EDUARDO, JUNIOR, MARQUEZANO DE MEDEIROS, ANA, CLAUDIA, UNILEVER N.V.
Application year: 1997
Main classification: C11D3
IPC codes: C11D3