BACKGROUND AND PRIOR ART Polyvinyl pyrrolidone and some related polymers are known ingredients of laundry detergent compositions, providing the benefit of reduced dye transfer between fabrics in a mixed load.

Laundry detergent compositions containing polyvinyl pyrrolidone as a dye transfer inhibitor are disclosed, for example, in WO 92 18597A, WO 94 03567A, WO 95 03390A, WO 95 17496A, WO 95 27028A and WO 95 34627A (Procter & Gamble), and WO 94 06354A, WO 94 24249A and WO 97 03166A (Henkel).

GB 1 354 498 (Unilever) discloses laundry detergent compositions containing vinyl pyrrolidone/vinyl acetate copolymers as antiredeposition agents. Polyvinyl pyrrolidone itself is stated to be ineffective.

It has now been discovered that polyvinyl pyrrolidone is also effective to enhance oily soil detergency, especially in detergent compositions containing anionic surfactants, more especially alkylbenzene sulphonate.

DEFINITION OF THE INVENTION The present invention provides the use of polyvinyl pyrrolidone in a laundry detergent composition comprising an organic surfactant and optionally a detergency builder to improve the oily soil detergency of the composition.

The polyvinyl pyrrolidone The polyvinyl pyrrolidone (hereinafter PVP) preferably has a molecular weight within the range of from 10 000 to 100 000, more preferably from 25 000 to 75 000.

PVP is commercially available, for example, from BASF as the Luviskol (Trade Mark) K series (powders and solutions of various concentrations) and Sokalan (Trade Mark) HP50 (powder), and from International Specialty Products (ISP) as the ISP-K series.

The laundry detergent composition In a laundry detergent composition in accordance with the invention, the PVP is present in an amount sufficient to enhance oily soil detergency. Suitably the PVP is present in an amount of from from 0.5 to 3 wt%, preferably from 1 to 2 wt%.

The detergent composition may suitably comprise: (a) from 5 to 60 wt%, preferably from 10 to 40 wt%, of organic surfactant, (b) optionally from 5 to 80 wt%, preferably from 10 to 60 wt%, of detergency builder, (c) from 0.5 to 3 wt%, preferably from 1 to 2 wt%, of PVP, (d) optionally other detergent ingredients to 100 wt%.

The organic surfactant The detergent composition in accordance with the invention may contain any organic surfactants (detergent-active compounds) suitable for incorporation into laundry detergent compositions.

Detergent-active compounds (surfactants) may be chosen from soap and non-soap anionic, cationic, nonionic, amphoteric and zwitterionic detergent-active compounds, and mixtures thereof. Many suitable detergent-active compounds are available and are fully described in the literature, for example, in"Surface-Active Agents and Detergents", Volumes I and II, by Schwarz, Perry and Berch. The preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds. The total amount of surfactant present is suitably within the range of from 5 to 60 wt%, preferably from 5 to 40 wt%.

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 C8-C15 ; primary and secondary

alkylsulphates, particularly C8-C20 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 Cl-so aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C1o-C15 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 R1R2R3R4N X wherein the R groups are long or short hydrocarbyl chains, typically alkyl, hydroxyalkyl or ethoxylated alkyl groups, and X is a solubilising anion (for example, compounds in which Rl is a Cg_C22 alkyl group, preferably a C8-C10 or C12-Cl4 alkyl group, R2 is a methyl group, and R3 and R4, which may be the same or different, are methyl or hydroxyethyl groups); and cationic esters (for example, choline esters).

Amphoteric surfactants and/or zwitterionic surfactants may also be present.

Preferred amphoteric surfactants are amine oxides. These are materials of the general formula

RlR2R3N-)-O wherein RI is typically a Cl-ci alkyl group, for example, C12-Cl4 alkyl, and R2 and R3, which may be the same or different, are C1-C3 alkyl or hydroxyalkyl groups, for example, methyl groups. The most preferred amine oxide is coco dimethylamine oxide.

Preferred zwitterionic surfactants are betaines, and especially amidobetaines. Preferred betaines are C8-C18 alkyl amidoalkylbetaines, for example, coco amidopropyl betaine (CAPB).

According to a preferred embodiment of the invention, the composition comprises a sulphonate anionic surfactant.

According to an especially preferred embodiment, the sulphonate anionic surfactant comprises linear alkylbenzene sulphonate (LAS).

An especially favourable interaction between LAS and PVP has been observed, giving improved primary detergency on difficult oily soils such as dirty motor oil. Without being bound by theory, it is postulated that the this benefit may be attributed to a reduction in the critical micelle concentration (CMC) of the LAS.

The known benefit of dye transfer inhibition is also observed.

Preferably, the compositions contains from 3 to 30 wt%, more preferably from 10 to 25 wt%, of LAS.

The optional detergency builder Preferably, the detergent compositions in accordance with the invention also contain one or more detergency builders.

The total amount of detergency builder in the compositions may suitably range from 5 to 80 wt%, preferably from 10 to 60 wt%.

Preferred builders are alkali metal aluminosilicates, more especially crystalline alkali metal aluminosilicates (zeolites), preferably in sodium salt form.

Zeolite builders may suitably be present in a total amount of from 5 to 60 wt%, preferably from 10 to 50 wt%.

The zeolites may be supplemented by other inorganic builders, for example, amorphous aluminosilicates, or layered silicates such as SKS-6 ex Clariant.

The zeolites may be supplemented by organic builders, for example, polycarboxylate polymers such as polyacrylates and acrylic/maleic copolymers; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di-and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates, hydroxyethyliminodiacetates, alkyl-and alkenylmalonates and succinates; and sulphonated fatty acid salts.

Alternatively, the compositions in accordance with the invention may contain phosphate builders, for example, sodium tripolyphosphate.

Especially preferred organic builders are citrates, suitably used in amounts of from 1 to 30 wt%, preferably from 2 to 15 wt%; and acrylic polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt%, preferably from 1 to 10 wt%. Builders, both inorganic and organic, are preferably present in alkali metal salt, especially sodium salt, form.

According to a preferred embodiment of the invention, the detergency builder, which is present in an amount of from 5 to 80 wt%, preferably from 10 to 60 wt%, is selected from sodium tripolyphosphate, zeolites, sodium carbonate and mixtures thereof.

Other detergent ingredients Detergent compositions in accordance with the invention may also suitably contain a bleach system. Preferably this will include a peroxy bleach compound, for example, an inorganic persalt or an organic peroxyacid, capable of yielding hydrogen peroxide in aqueous solution.

Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, the latter being especially preferred. The sodium percarbonate may have a protective coating against destabilisation by moisture. The peroxy bleach compound is suitably present in an amount of from 5 to 35 wt%, preferably from 10 to 25 wt%.

The peroxy bleach compound may be used in conjunction with a bleach activator (bleach precursor) to improve bleaching action at low wash temperatures. The bleach precursor is suitably present in 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).

A bleach stabiliser (heavy metal sequestrant) may also be present. Suitable bleach stabilisers include ethylenediamine tetraacetate (EDTA), diethylenetriamine pentaacetate (DTPA), ethylenediamine disuccinate (EDDS), and the polyphosphonates such as the Dequests (Trade Mark), ethylenediamine tetramethylene phosphonate (EDTMP) and diethylenetriamine pentamethylene phosphate (DETPMP).

The compositions in accordance with the invention may contain alkali metal, preferably sodium, carbonate, in order to increase detergency and ease processing. Sodium carbonate may suitably be present in amounts ranging from 1 to 60 wt%, preferably from 2 to 40 wt%.

As previously indicated, sodium silicate may also be present. The amount of sodium silicate may suitably range from 0.1 to 5 wt%. Sodium silicate, as previously indicated, is preferably introduced via the second base granule.

Powder flow may be improved by the incorporation of a small amount of a powder structurant. Examples of powder structurants, some of which may play other roles in the formulation as previously indicated, include, for example, fatty acids (or fatty acid soaps), sugars, acrylate or acrylate/maleate polymers, sodium silicate, and dicarboxylic acids (for example, Sokalan (Trade Mark) DCS ex BASF). One preferred powder structurant is fatty acid soap, suitably present in an amount of from 1 to 5 wt%.

Other materials that may be present in detergent compositions in accordance with the invention include antiredeposition agents such as cellulosic polymers; soil release agents; anti-dye-transfer agents; fluorescers; inorganic salts such as sodium sulphate; enzymes (proteases, lipases, amylases, cellulases); dyes; coloured speckles; perfumes; and fabric conditioning compounds.

This list is not intended to be exhaustive.

Product form and preparation The compositions in accordance with 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 in particulate form.

Powders of low to moderate bulk density may be prepared by spray-drying a slurry, and optionally postdosing (dry- mixing) further ingredients."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.

Tablets may be prepared by compacting powders, especially "concentrated"powders.

Also preferred are liquid detergent compositions, which may be prepared by admixing the essential and optional ingredients in any desired order to provide compositions containing the ingredients in the requisite concentrations.

Incorporation of the PVP The PVP may be incorporated at any suitable stage in the manufacture of the compositions in accordance with the invention. As previously indicated, PVP is commercially available both in solution form and in solid form.

For example, in the manufacture of spray-dried particulate compositions, PVP in powder or solution (preferably aqueous) form may be incorporated in the slurry. For non-tower particulates, PVP powder or solution may be easily introduced into mixing and granulating apparatus, either alone or in admixture with other solid or liquid ingredients as appropriate.

EXAMPLES The invention is further illustrated by the following Examples, in which parts and percentages are by weight unless otherwise stated.

EXAMPLES 1 to 8, COMPARATIVE EXAMPLES A and B Detergency benefits on dirty motor oil using model wash liquors Wash liquors containing 1 g/litre or 2.5 g/litre of a notional detergent composition (the"product") containing linear alkylbenzene sulphonate (LAS) and sodium carbonate were prepared to the following general formulation:

Ingredient Weight% in Weight% in Weight% in "product"1 g/l wash 2.5 g/1 wash liquor liquor Sodium LAS 14. 82 0. 1482 0. 3705 Sodium 11. 50 0. 1150 0. 2785 carbonate PVP 0,0. 20 or 0, 0.0020 or 0,0. 0050 or 0.80 0.0080 0.0200 Water Balance Balance Balance The PVP samples used were as follows: Example Trade Molecular name weight 1,2, 5, 6 ISP-K15 10 000 3, 4,7, 8 ISP-K30 30 000

Detergency on white cotton cloth soiled with dirty motor oil was assessed using a high throughput small scale wash method. The wash was carried out in water of 20 (French)

hardness (Ca: Mg 2: 1), at a temperature of 20 C for 20 minutes.

Whiteness before and after the wash was determined using the technique of colour change by image analysis using a greyness scale. The results are analogous to reflectance changes at 460 nm as measured by a reflectance spectrophotometer and are expressed as AR and AAR.

Results at 1 g/litre"product"concentration Example Polymer Polymer level AR AAR in"product" A none 0 81.76 0 1 ISP-K15 0.2 81.56 - 0. 20 2 ISP-K15 0. 8 82. 80 + 1.04 3 ISP-K30 0. 2 82. 58 + 0.82 4 ISP-K30 0. 8 82. 54 + 0.78

Results at 2.5 g/litre"product"concentration Example Polymer Polymer level AR AAR in"product" B none 0 82.04 0 5 ISP-K15 0.2 82.27 + 0.23 6 ISP-K15 0.8 84. 23 + 2.19 7 ISP-K30 0. 2 82. 88 + 0.84 8 ISP-K30 0. 8 82. 73 + 0.69

EXAMPLE 9 Particulate detergent composition The formulation below is an example of a built particulate laundry detergent composition that may be used in accordance with the invention.

Ingredient Weight% Sodium linear alkylbenzene sulphonate 9.31 Nonionic surfactant 3.58 Sodium tripolyphosphate 21.32 Sodium carbonate 12.97 Sodium hydroxide 1.95 Sodium carboxymethyl cellulose 0.62 Sodium silicate (r = 2.4) 5.18 Fluorescers 0.13 Zeolite 1. 24 Sodium perborate tetrahydrate 15.00 Tetraacetyl ethylenediamine 3.80 Enzymes 2.27 (protease, lipase, amylase) Antifoam granule 2.00 Dequest 2047 0.50 Granular sodium tripolyphosphate 10.00 Perfume 0.65 Citric acid 2.75 Polyvinyl pyrrolidone 1.0-2. 0 Water to 100.00