DETERGENT COMPOSITIONS

Abstract: A laundry detergent composition comprises surfactant, builder, and optionally other non-bleach detergent ingredients, and also contains a low level of a polymer containing structural units of a condensation product of an amino acid (for example, aspartic acid) and an unsaturated dicarboxylic acid (for example, maleic acid). The composition provides improved maintenance of colour fidelity, especially of white or light-coloured fabrics, on laundering.

Description: DETERGENT COMPOSITIONS TECHNICAL FIELD The present invention relates to laundry detergent compositions giving especial benefits m the laundering of white fabrics. The compositions of the invention, which contain a polymeric sequestrant, have been found to give improved maintenance of colour fidelity, especially of white and light-coloured fabrics, during the wash. BACKGROUND AND PRIOR ART In some countries the water supply contains a relatively high concentration of iron and this can lead to the discolouration (yellowing) of white and light-coloured fabrics on laundering due to the deposition of Fe(III) salts. This changes the appearance and shortens the useful life of the articles. EP 802 177A (Nippon Sho ubai) discloses water-soluble ammocarboxylic monomers which are condensation products of an ammo acid with a dicarboxylic acid anhydride, for example aspartic acid/maleic anhydride, and homo- and copolymers thereof . Copoly ers of these monomers with acrylic acid and/or maleic acid exhibit excellent chelatmg and dispersing properties and may be incorporated m detergent compositions, for example, at a level of 20 wt% based on the composition. It has now been found that significantly improved maintenance of whiteness or colour fidelity may be observed if a water-soluble polymer of this type is incorporated at low levels a laundry detergent composition. EP 476 257A (Huls) discloses ammodicarboxylic acids and their derivatives as bleach stabilisers m the washing of textile fabrics. EP 441 563A (Unilever) discloses laundry detergent compositions containing vmyl carbamates and their homo- and copolymers as sequestering agents and detergency builders . DEFINITION OF THE INVENTION The present invention provides a laundry detergent composition comprising surfactant, builder, and optionally other non-bleach detergent ingredients, and also containing from 0.01 to 2.0 wt% of a water-soluble polymer comprising structural units of the formula I 2 I CH - C (I) Ri C = O NH - CH - COOX CH 2 - R 3 wherein R x is H or COOX, R 2 is H or CH 2 COOX but Ri and R 2 cannot both be H, R 3 is COOX, OH or CH 2 COOX, and each X is individually H or a solubilismg cation. A further subject of the invention is a method of protecting new white or light-coloured textile fabrics from colour degradation on laundering, which comprises laundering the fabrics by hand or machine m a wash liquor containing a detergent composition as defined above. A further subject of the invention is the use of a polymer as defined above m a laundry detergent composition to protect new white or light-coloured textile fabrics from colour degradation on laundering. The term "colour fidelity" is used herein to include both the true colour of coloured fabrics and the whiteness of white fabrics. The benefits of the present invention are especially applicable to white or light-coloured fabrics where iron deposition will cause the greatest deterioration in appearance . DETAILED DESCRIPTION OF THE INVENTION The water-soluble polymeric sequestrant The polymeric sequestrant used in the compositions of the invention is a water-soluble polymer comprising structural units of the formula I R 2 - CH - C - (I) R x C = 0 I NH - CH - COOX wherein R ± is H or COOX, R 2 is H or CH 2 COOX but Ri and R 2 cannot both be H, R 3 is COOX, OH or CH 2 COOX, and each X is individually H or a solubilising cation. These polymers are described and claimed in EP 802 177A (Nippon Shokubai) , which describes and claims also the monomers from which they are derived, and detergent compositions containing the polymers. An example contains 20 wt% of the polymer. The aminocarboxylic monomers from which the structural units of the formula I are derived are condensation products of an amino acid, for example, aspartic acid, serine or glutamic acid with the anhydride of an unsaturated dicarboxylic acid, for example, maleic anhydride, itaconic anhydride or aconitic anhydride. An especially preferred monomer is the condensation product of aspartic acid with maleic anhydride, giving in the polymer structural units of the formula I in which Ri is COOX, R 2 is H and R 3 is COOX. The water-soluble polymers may be homo- or copolymers. Especially preferred are copolymers comprising at least 15 mole%, preferably at least 20 mole%, of structural units of the formula I . The copolymers may further comprise structural units of unsaturated mono- or dicarboxylic acids. Preferred copolymers contain structural units of maleic acid and/or acrylic acid. Preferred copolymers comprise from 15 to 50 mole% of structural units of the formula I, from 50 to 85 mole% of structural units of acrylic acid, and optionally from 0 to 15 mole% of structural units of maleic acid. Especially preferred are terpolymers comprising from 20 to 30 mole% of structural units of the formula I, from 60 to 80 mole% of structural units of acrylic acid, and from 1 to 10 mole% of structural units of maleic acid. An especially preferred polymer contains 25 mole% of structural units of a condensation product of aspartic acid and maleic anhydride (MA-Asp) , 5 mole% of maleic acid (MA) units, and 70 mole% of acrylic acid (AA) units. This polymer will be referred to hereinafter as a MA-Asp/MA/AA terpolymer. The polymer suitably has a weight average molecular weight of from 800 to 8 million, preferably from 1000 to 100 000. Polymers having a weight average molecular weight of from 2000 to 10 000 are preferred. Amount of polymeric sequestrant The polymer may suitably be present m the composition m the invention m an amount of from 0.01 to 2 wt%, more preferably from 0.02 to 1 wt% and most preferably from 0.03 to 0.5 wt%. The polymeric sequestrant is effective at very low concentration levels in the composition. No additional benefit is seen at higher concentration levels, for example, above 2 wt% . Detergent compositions The composition of the invention also contains other conventional detergent ingredients. Essential ingredients are surfactants (detergent-active compounds) and detergency builders, and other conventional ingredients may optionally be present . Detergent compositions of the invention may suitably comprise from 5 to 60 wt% of one or more detergent surfactants and from 10 to 80 wt% of one or more detergency builders, as well as the preferred amounts of the polymeric sequestrant, and optionally other detergent ingredients to 100 wt%. According to one preferred embodiment of the invention, the compositions of the invention may be substantially free of bleaching ingredients. Detergent ingredients The detergent compositions will contain, as essential ingredients, one or more detergent active compounds (surfactants) which may be chosen from soap and non-soap anionic, cationic, nomonic, amphoteric and zwitteriomc detergent active compounds, and mixtures thereof. Many suitable detergent active compounds are available and are fully described m the literature, for example, m "Surface-Active Agents and Detergents", Volumes I and II, by Schwartz, Perry and Berch. The preferred detergent active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds . Anionic surfactants are well-known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly linear alkylbenzene sulphonates having an alkyl chain length of C 8 -C 15 ; primary and secondary alkylsulphates , particularly C 8 -Cι 5 primary alkyl sulphates; alkyl ether sulphates; olefin sulphonates; alkyl xylene sulphonates; dialkyl sulphosuccinates ; and fatty acid ester sulphonates. Sodium salts are generally preferred. Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C 8 -C 2 o aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the Cι 0 -Cι 5 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Non-ethoxylated nonionic surfactants include alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides (glucamide) . Cationic surfactants that may be used include quaternary ammonium salts of the general formula R ! R 2 R 3 R 4 N + X " wherein the R groups are long or short hydrocarbyl chains, typically alkyl, hydroxyalkyl or ethoxylated alkyl groups, and X is a solubilising cation (for example, compounds in which R is a C 8 -C 22 alkyl group, preferably a C 8 -Cι 0 or Cι 2 -Cι 4 alkyl group, R 2 is a methyl group, and R 3 and R 4 , which may be the same or different, are methyl or hydroxyethyl groups) ; and cationic esters (for example, choline esters) . In an especially preferred cationic surfactant of the general formula RιR 2 R 3 R 4 N + X , Ri represents a C 8 -Cι 0 or Cι 2 -Cι 4 alkyl group, R 2 and R 3 represent methyl groups, and R 4 presents a hydroxyethyl group. Amphoteric surfactants, for example, amme oxides, and zwitterionic surfactants, for example, betames, may also be present . Preferably, the quantity of anionic surfactant is m the range of from 5 to 50% by weight of the total composition. More preferably, the quantity of anionic surfactant is m the range of from 8 to 35% by weight. Nonionic surfactant, if present, is preferably used m an amount within the range of from 1 to 20% by weight. The total amount of surfactant present is preferably withm the range of from 5 to 60 wt%. The compositions may suitably contain from 10 to 80%, preferably from 15 to 70% by weight, of detergency builder. Preferably, the quantity of builder is the range of from 15 to 50% by weight. The detergent compositions may contain as builder a crystalline alummosilicate, preferably an alkali metal alummosilicate, more preferably a sodium alummosilicate (zeolite) . The zeolite used as a builder may be the commercially available zeolite A (zeolite 4A) now widely used in laundry detergent powders. Alternatively, the zeolite may be maximum aluminium zeolite P (zeolite MAP) as described and claimed in EP 384 070B (Unilever) , and commercially available as Doucil (Trade Mark) A24 from Crosfield Chemicals Ltd, UK. Zeolite MAP is defined as an alkali metal alummosilicate of zeolite P type having a silicon to aluminium ratio not exceeding 1.33, preferably within the range of from 0.90 to 1.33, preferably within the range of from 0.90 to 1.20. Especially preferred is zeolite MAP having a silicon to aluminium ratio not exceeding 1.07, more preferably about 1.00. The particle size of the zeolite is not critical. Zeolite A or zeolite MAP of any suitable particle size may be used. Also preferred according to the present invention are phosphate builders, especially sodium tripolyphosphate . This may be used in combination with sodium orthophosphate, and/or sodium pyrophosphate . Other inorganic builders that may be present additionally or alternatively include sodium carbonate, layered silicate, amorphous aluminosilicates . Organic builders that may be present include polycarboxylate polymers such as polyacrylates and acrylic/maleic copolymers; polyaspartates ; monomeπc polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-di- and trisuccinates, carboxymethyloxysuccinates , carboxy- methyloxymalonates , dipicolinates, hydroxyethylimmodiacetates, alkyl- and alkenylmalonates and succmates; and sulphonated fatty acid salts. Organic builders may be used m minor amounts as supplements to inorganic builders such as phosphates and zeolites. Especially preferred supplementary organic builders are citrates, suitably used m amounts of from 5 to 30 wt %, preferably from 10 to 25 wt % ; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used m amounts of from 0.5 to 15 wt %, preferably from 1 to 10 wt%. Builders, both inorganic and organic, are preferably present m alkali metal salt, especially sodium salt, form. Detergent compositions according to the invention may also suitably contain a bleach system, although, as previously indicated, non-bleach g formulations are also withm the scope of the invention. The bleach system is preferably based on peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, capable of yielding hydrogen peroxide m aqueous solution. Suitable peroxy bleach compounds include organic peroxides such as urea peroxide, and inorganic persalts such as the alkali metal perborates, percarbonates, perphosphates, persilicates and persulphates . Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate . Especially preferred is sodium percarbonate having a protective coating against destabilisation by moisture. Sodium percarbonate having a protective coating comprising sodium metaborate and sodium silicate is disclosed m GB 2 123 044B (Kao) . The peroxy bleach compound is suitably present m an amount of from 5 to 35 wt%, preferably from 10 to 25 wt%. The peroxy bleach compound may be used m conjunction with a bleach activator (bleach precursor) to improve bleaching action at low wash temperatures. The bleach precursor is suitably present m an amount of from 1 to 8 wt%, preferably from 2 to 5 wt%. Preferred bleach precursors are peroxycarboxylic acid precursors, more especially peracetic acid precursors and peroxybenzoic acid precursors; and peroxycarbonic acid precursors. An especially preferred bleach precursor suitable for use in the present invention is N,N,N',N'- tetracetyl ethylenediamine (TAED) . The novel quaternary ammonium and phosphonium bleach precursors disclosed m US 4 751 015 and US 4 818 426 (Lever Brothers Company) and EP 402 971A (Unilever) are also of great interest. Especially preferred are peroxycarbonic acid precursors, m particular cholyl-4-sulphophenyl carbonate. Also of interest are peroxybenzoic acid precursors, m particular, N,N,N-tnmethylammonιum toluoyloxy benzene sulphonate; and the cationic bleach precursors disclosed EP 284 292A and EP 303 520A (Kao) . A bleach stabiliser (heavy metal sequestrant) may also be present. Suitable bleach stabilisers include ethylenediam e tetraacetate (EDTA) and the polyphosphonates such as Dequest (Trade Mark), EDTMP . The detergent compositions may also contain one or more enzymes. Suitable enzymes include the proteases, amylases, cellulases, oxidases, peroxidases and lipases usable for incorporation m detergent compositions. Preferred proteolytic enzymes (proteases) are catalytically active protein materials which degrade or alter protein types of stains when present as fabric stains m a hydrolysis reaction. They may be of any suitable origin, such as vegetable, animal, bacterial or yeast origin. Proteolytic enzymes or proteases of various qualities and origins and having activity m various pH ranges of from 4-12 are available. Proteases of both high and low isoelectric point are suitable. Other enzymes that may suitably be present include lipases, amylases, and cellulases including high-activity cellulases such as "Carezyme") . In particulate detergent compositions, detergency enzymes are commonly employed m granular form m amounts of from about 0.1 to about 3.0 wt%. However, any suitable physical form of enzyme may be used m any effective amount. Antiredeposition agents, for example cellulose esters and ethers, for example sodium carboxymethyl cellulose, may also be present . The compositions may also contain soil release polymers, for example sulphonated and unsulphonated PET/POET polymers, both end-capped and non-end-capped, and polyethylene glycol/polyvmyl alcohol graft copolymers such as Sokolan (Trade Mark) HP22. Especially preferred soil release polymers are the sulphonated non-end-capped polyesters described and claimed in WO 95 32997A (Rhodia Chimie) . Other ingredients that may be present include solvents, hydrotropes, fluorescers, photobleaches , foam boosters or foam controllers (antifoams) as appropriate, sodium carbonate, sodium bicarbonate, sodium silicate, sodium sulphate, calcium chloride, other inorganic salts, fabric conditioning compounds, and perfumes. Product form and preparation As previously indicated, the compositions of the invention may be of any suitable physical form, for example, particulates (powders, granules, tablets), liquids, pastes, gels or bars. According to one especially preferred embodiment of the invention, the detergent composition is m particulate form. If necessary, the polymeric sequestrant may be incorporated m particulate compositions the form of granules containing an inert carrier material . Powders of low to moderate bulk density may be prepared by spray-drying a slurry, and optionally postdosmg (dry- mixmg) further ingredients, which case the polymeric sequestrant may be either incorporated via the slurry or postdosed. "Concentrated" or "compact" powders may be prepared by mixing and granulating processes, for example, using a high-speed mixer/granulator, or other non-tower processes . According to another especially preferred embodiment of the invention, the detergent composition is liquid form. Liquid detergent compositions may be prepared by admixing the essential and optional ingredients m any desired order to provide compositions containing the ingredients m the the requisite concentrations. EXAMPLES The invention will now be illustrated m further detail by means of the following Examples, which parts and percentages are by weight unless otherwise stated. In the Examples the following abbreviations are used: MA-Asp/MA/AA Terpolymer (25/5/70) of aspartate/maleate, maleate and acrylate, M w 5000 (ex Nippon Shokubai) EDDS Ethylenediamme disuccmate, sodium salt EDTMP Ethylenediamme tetramethylene phosphonate, calcium salt: Dequest (Trade Mark) 2047 ex Monsanto NaLAS Sodium linear alkylbenzene sulphonate SLES Sodium lauryl ether sulphate SCMC Sodium carboxymethyl cellulose EXAMPLES 1 to 3, COMPARATIVE EXAMPLES A to D Protection of new white cotton fabrics from discolouration by Fe(III) ions using sequestrants In this experiment, the effectivness of the polymeric sequestrant MA-Asp/MA/AA preventing the discolouration of white cotton fabric was compared with that of two known sequestrants, EDTMP (Dequest 2047) and EDDS. The experimental procedure was as follows. The sequestrants, m the concentrations indicated below, were added to 1 litre of demmeralised water containing iron (III) chloride m an amount sufficient to give a Fe(III) concentration of 10 ppm, m a tergotometer pot. The pH of the solution was adjusted to 9.5 (±0.1) by adding sodium hydroxide solution. Three 10x10 cm pieces (approximately 5 grams) of desized non- fluorescent white cotton cloth were added to provide a liquor to cloth ratio of 200:1. A tergotometer wash was then carried out at 30°C and 90 rpm for 30 minutes. The cloths were then rinsed m demmeralised water and dried overnight. Reflectance values at 420nm were taken for the cloths before and after washing, and ΔR at 420nm calculated to give an indication of the amount of iron deposition onto the cloth. The ideal here is for a result as close as possible to zero, indicating no deposition of iron and no visible deterioration in appearance. The concentrations for the sequestrants were chosen as follows : 0.008 g/1, equivalent to 0.2 wt% of a detergent composition used at a typical consumer dosage of 4 g/1. 0.002 g/1, equivalent to 0.05 wt% of a detergent composition used at a typical consumer dosage of 4 g/1. 0.0008 g/1, equivalent to 0.02 wt% of a detergent composition used at a typical consumer dosage of 4 g/1. Average changes in reflectance are shown in the following Table. EDTMP is an excellent sequestrant but has come under some scrutiny on environmental grounds because of its phosphorus content. EDDS has been widely proposed as a zero-phosphorus replacement . It will be seen that the polymeric sequestrant provides a phosphorus -free alternative to EDTMP that is substantially superior to EDDS . EXAMPLES 4 to 9 Detergent compositions Example 4 spray-dried detergent powder Examples 5 to 7 : concentrated detergent powders Examples 8 and 9: liquid detergent compositions

Claims: CLAIMS 1 A laundry detergent composition comprising surfactant, builder, and optionally other non-bleach detergent ingredients, charaterised in that it also contains from 0.01 to 2.0 wt% of a water-soluble polymer comprising structural units of the formula I R 2 CH - C - (I) R x C = O I NH - CH - COOX I CH 2 - R 3 wherein Ri is H or COOX, R 2 is H or CH 2 COOX but Ri and R 2 cannot both be H, R 3 is COOX, OH or CH 2 COOX, and each X is individually H or a solubilising cation. 2 A detergent composition as claimed in claim 1, characterised in that in the formula I Ri is COOX, R 2 is H and R 3 is COOX. 3 A detergent composition as claimed in claim 1 or claim 2, characterised in that the polymer is a copolymer comprising at least 15 mole%, preferably at least 20 mole%, of structural units of the formula I . 4 A detergent composition as claimed in claim 3, characterised in that the polymer is a copolymer further comprising structural units of an unsaturated monocarboxylic acid and/or an unsaturated dicarboxylic acid. 5 A detergent composition as claimed in claim 4, characterised in that the polymer is a copolymer comprising from 15 to 50 mole% of structural units of the formula I, from 50 to 85 mole% of structural units of acrylic acid, and optionally from 0 to 15 mole% of structural units of maleic acid. 6 A detergent composition as claimed in claim 5, characterised in that the polymer is a copolymer comprising from 20 to 30 mole% of structural units of the formula I, from 60 to 80 mole% of structural units of acrylic acid, and from 1 to 10 mole% of structural units of maleic acid. 7 A detergent composition as claimed in any preceding claim, characterised in that the polymer has a weight average molecular weight within the range of from 1000 to 100 000, preferably from 2000 to 10 000. 8 A detergent composition as claimed in any preceding claim, characterised in that the polymer is present in an amount of from 0.02 to 1 wt%, preferably from 0.03 to 0.5 wt%, based on the composition. 9 A detergent composition as claimed in any preceding claim, characterised in that it comprises from 5 to 60 wt% of one or more detergent surfactants and from 10 to 80 wt% of one or more detergency builders. 10 A detergent compound as claimed in any preceding claim, characterised in that it is substantially free of bleach ingredients. 11 A method of protecting new white or light-coloured textile fabrics from colour degradation on laundering, characterised in that it comprises laundering the fabrics by hand or machine in a wash liquor containing a detergent composition as claimed in any one of claims 1 to 10. 12 Use of a water-soluble polymer comprising structural units of the formula I R 2 I CH - C (II) Ri C = O NH - CH - COOX CH 2 - R 3 wherein R λ is H or COOX, R 2 is H or CH 2 COOX but Ri and R 2 cannot both be H, R 3 is COOX, OH or CH 2 COOX, and each X is individually H or a solubilising cation, in a laundry detergent composition to protect new white or light -coloured textile fabrics from colour degradation on laundering.

Inventors: TYNAN MATTHEW, WESTWELL JEREMY ROBERT, TYNAN, MATTHEW, WESTWELL, JEREMY, ROBERT
Applicants: LEVER HINDUSTAN LTD, TYNAN MATTHEW, UNILEVER NV, UNILEVER PLC, WESTWELL JEREMY ROBERT, HINDUSTAN LEVER LIMITED, TYNAN, MATTHEW, WESTWELL, JEREMY, ROBERT
Application year: 2000
Main classification: C11D3
IPC codes: C11D3