GB2340500A

GB2340500A - Laundry detergent compositions

Info

Publication number: GB2340500A
Application number: GB9817282A
Authority: GB
Inventors: Nigel Peter Bird; Lynn Cowie; Rosidah Radzian; Chandulal Kantilal Ranpuria
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1998-08-07
Filing date: 1998-08-07
Publication date: 2000-02-23
Also published as: GB9817282D0; ZA200100977B

Abstract

A built particulate laundry detergent composition contains a surfactant system, a builder system, and from 0.02 to 5 wt% of a decoupling polymer (deflocculating polymer) such as poly(lauryl methacrylate-co-acrylate). The inclusion of the polymer gives improved stain removal and also facilitates processing of spray-dried powders if incorporated via the slurry. Cleaning performance may be enhanced further by the incorporation of further stain removal agents, preferably selected from sequestrants, reducing bleaches and photobleaches.

Description

I PC3862 2340500 DETERGENT COMPOSITIONS

TECHNICAL FIELD

The present invention is concerned with built particulate laundry detergent compositions giving improved stain removal on certain stubborn stains. The compositions of the invention contain a decoupling polymer.

BACKGROUND

Decoupling polymers, also referred to as deflocculating polymers, are polymers containing a hydrophilic backbone and at least one hydrophobic side chain. The best known example is poly (lauryl methacrylate-coacrylate), in which a polyacrylic acid backbone has side chains derived from lauryl methacrylate.

These polymers are used in structured aqueous liquid laundry detergent compositions. These compositions, which are generally translucent or semi-opaque in appearance, take the form of a dispersion of surfactant lamellar droplets dispersed in a continuous aqueous phase. The polymers provide improved stability 'and, generally, also decrease viscosity. Their incorporation in liquid detergent compositions is therefore for the purpose of optimising the physical form and not for reasons of performance.

PC3862 2 It has now surprisingly been discovered that these polymers, if incorporated at low levels in built particulate laundry detergent compositions, give enhanced stain removal on certain highly coloured stains. Additionally, there is a processing benefit in powders produced by spray-drying an aqueous slurry: incorporation of decoupling polymer in the slurry lowers slurry viscosity and enables slurries of lower moisture content than hitherto to be produced without viscosity rising to an unmanageable level. A slurry of lower moisture content requires less energy for drying; and its higher active matter content allows a higher throughput in the spray-drying process.

PRIOR ART

EP 346 995A, EP 506 695A, EP 495 858A, WO 91 05845A and EP 504 150A (Unilever) disclose aqueous liquid laundry detergent compositions containing decoupling or deflocculating polymers, for example, lauryl (methacrylateco-acrylate).

PC3862 3 DEFINITION OF THE INVENTION The present invention accordingly provides a built particulate laundry detergent composition comprising 5 (a) from 5 to 40 wt% of a surfactant system comprising one or more anionic, nonionic, cationic, amphoteric or zwitterionic surfactants, (b) from 10 to 80 wt% of a detergency builder, (c) from 0.02 to 5 wt%, preferably from 0.05 to 2 wt%, of a decoupling polymer, (d) other detergent ingredients to 100 wt%.

The invention further provides a process for the preparation of a built particulate detergent composition as defined in the previous paragraph, which process comprises spray-drying an aqueous slurry to form a base powder and admixing (postdosing) additional ingredients as necessary, wherein the decoupling polymer is incorporated via the slurry into the base powder.

PC3862 4 DETAILED DESCRIPTION OF THE INVENTION

The decoupling polymer Decoupling or deflocculating polymers are described in detail in EP 346 995A (Unilever). These polymers consist of a hydrophilic backbone and at least one hydrophobic side chain. Generic structures and preferred materials are disclosed exhaustively in EP 346 995A.

Preferred hydrophilic polymer backbones include polyacrylic, polymaleic, polytartronic, polycitric and polygluconic acids, and mixtures thereof, in acid or wholly or partially neutralised form. In especially preferred polymers, the hydrophilic backbone comprises acrylic or maleic units in acid or salt form. The most preferred hydrophilic backbone is polyacrylic acid.

The hydrophobic side chain preferably includes an alkyl or alkenyl chain containing at least 5 carbon atoms, and more preferably from 8 to 18 carbon atoms. Preferred hydrophobic monomers are C8-Cj8 esters of methacrylic acid. The most preferred hydrophobic monomer is lauryl methacrylate.

The monomer ratio of hydrophilic monomer to hydrophobic monomer is preferably from 4:1 to 1000:1, more preferably from 6:1 to 250:1.

An especially preferred polymer is a copolymer of polyacrylic acid with lauryl methacrylate, otherwise referred to as poly(lauryl methacrylate-coacrylate). The preferred monomer ratio of acrylic acid to lauryl PC3862 methacrylate is about 25:1. This material is available commercially as Narlex (Trade Mark) DC-1 from National Starch and Chemical Company.

In the detergent compositions of the invention, the decoupling polymer is present in an amount of from 0.02 to 5 wt%, preferably from 0.05 to 2 wt%, more preferably about 1 wt%.

Stain removal agents According to a preferred embodiment of the invention, the cleaning performance of the compositions of the invention may be further enhanced by the inclusion of an effective amount of a further stain removal agent. The amount of the further stain removal agent depends on the material chosen but is generally within the range of from 1 to 10 wt%.

Preferred stain removal agents are selected from the following list:

sequestrants, for example, nitrilotriacetic acid and its salts (NTA), typically used in amounts of from 0.5 to 5 wt%; reducing bleaches, for example, sodium sulphite, typically used in amounts of from 5 to 10 wt%; photobleaches, and especially metal phthalocyanine compounds.

Preferred photobleaches are aluminium and zinc phthalocyanines, preferably sulphonated aluminium and zinc PC3862 6 phthalocyanines. These materials may be suitably be used in amounts of from 0.0005 to 0.05 wt%, more preferably from 0.002 to 0.015 wt%. An especially preferred photobleach is aluminium phthalocyanine sulphonate (A1PCS), suitably in the form of a granule containing 0.1% A1PCS on a bentonite clay carrier, the granule suitably being used in amounts of from 0.5 to 5 wt% so that the active ingredient is present in an amount of from 0.0005 to 0.005 wt%. The granule is available commercially from Stid-Chemie AG as Laundrosil (Trade Mark) RT, containing 1% of Tinopal (Trade Mark) BBS (a 10 wt% aqueous solution of A1PCS available from Ciba Speciality Chemicals) dispersed on bentonite clay.

The surfactant system 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, 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 Schwartz, Perry and Berch.

The total amount of surfactant present is from 5 to 40 wt%, preferably from 15 to 35 wt%.

The preferred detergent active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds.

PC3862 7 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-C15 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 C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C10-Cls primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol. Nonethoxylated 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 cation (for example, compounds in which R, is a C8-C22 alkyl group, preferably a C8-Clo or C12-CI4 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).

The choice of surfactant system is not critical. However, the surfactant advantageously comprises a sulphonate or sulphate type anionic surfactant, preferably alkylbenzene sulphonate or a primary alcohol sulphate.

PC3862 8 The anionic surfactant may suitably be present in an amount of from 10 to 35 wt%, more preferably from 15 to 30 wt%.

The anionic surfactant may be the sole surfactant present.

Alternatively, it may be used in combination with one or more cosurfactants. A suitable system comprises:

(a) from 10 to 28 wt%, preferably from 10 to 25 wt%, of a sulphonate or sulphate type anionic surfactant, preferably alkylbenzene sulphonate or primary alcohol sulphate; (b) from 1 to 10 wt%, preferably from 1.5 to 8 wt%, of one or more cosurfactants selected from cationic, nonionic, amphoteric, zwitterionic and ethoxylated anionic surfactants, all percentages being based on the total detergent composition.

Preferably the total amount of surfactants (a) and (b) is from 18 to 28 wt%, more preferably from 18 to 25 wt%, and preferably the ratio of surfactant (a) to cosurfactant (b) is from 1.5:1 to 20:1, more preferably from 1.5:1 to 12:1.

One especially preferred class of cosurfactants is comprised by ethoxylated alcohol nonionic surfactants. Nonionic surfactants that may be present include the primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from I to 30 20 moles of ethylene oxide per mole of alcohol, and more especially the C10-C15 primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol.

PC3862 9 Compositions of the invention may be suitable either for washing by hand or machine washing or both. For compositions intended especially for the hand wash, the cosurfactant (b) is preferably milder to the skin than the surfactant (a), as described and claimed in our copending application of even date (Case C98/044).

The cosurfactant may then suitably be chosen from amphoteric and zwitterionic surfactants. Nonionic or ethoxylated anionic surfactants may also be present.

Preferred amphoteric surfactants are amine oxides. These are materials of the general formula R1R2R3N ---)O wherein R, is typically a C8-CI8 alkyl group, for example, C12C14 alkyl, and R2 and R3. which may be the same or different. are Cl-C3 alkyl or hydroxyalkyl groups, for example, methyl groups. The most preferred amine oxide is coco dimethylamine oxide.

Amine oxides are preferably, but not invariably, used in combination with ethoxylated alcohol nonionic surfactants.

One preferred cosurfactant system comprises:

(b)(i) from 0.1 to 5 wt%, preferably from 0.3 to 3 wt%, of amine oxide, (b)(ii) from 0.5 to 5 wt%, preferably from 1 to 3 wt%, of an ethoxylated nonionic surfactant, PC3862 the total amount of (b)(i) and (b)(ii) being from I to 8 wt%, preferably from 2 to 6 wt% (all percentages being based on the detergent composition). Preferred zwitterionic surfactants are betaines, and especially amidobetaines. Preferred betaines are C8-Cjs alkyl amidoalkylbetaines, for example, coco amidopropyl betaine (CAPB).

Ethoxylated anionic surfactants, for example, alkyl ether sulphates (ethoxylated alcohol sulphates), may also be present.

Also suitable for use as cosurfactants in the compositions of the present invention are C8-Cjs alkyl monoethanolamides, for example, coco monoethanolamide.

Detergency builder The compositions also contain from 10 to 80%, preferably from 15 to 70% by weight, of detergency builder. Preferably, the quantity of builder is in the range of from 15 to 50% by weight.

One preferred class of inorganic builders comprises the phosphates, more especially sodium tripolyphosphate. Other possible phosphate builders are sodium orthophosphate and pyrophosphate. An especially preferred detergency builder comprises sodium tripolyphosphate, preferably present in an amount of from 10 to 40 wt%, more preferably from 15 to wt%, most preferably from 20 to 30 wt%.

PC3862 Alternatively or additionally, the detergent compositions of the invention may contain as builder a crystalline alkali metal (preferably sodium) aluminosilicate (zeolite).

Preferred zeolites are zeolite A (zeolite 4A), and zeolite MAP as described and claimed in EP 384 070B (Unilever) and commercially available as Doucil (Trade Mark) A24 from Crosfield Chemicals Ltd, UK.

As well as the phosphate or zeolite builders already mentioned, other inorganic or organic builders may be present.

Inorganic builders that may additionally be present include sodium carbonate, layered silicates, amorphous aluminosilicates. Sodium carbonate is also useful for powder structuring and control of pH. Preferably 5 to 30% by weight of sodium carbonate is present.

Organic builders that may additionally be present include polycarboxylate polymers such as polyacrylates and acrylic/maleic copolymers; polyaspartates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates, hydroxyethyl iminodiacetates, alkyl and alkenyl malonates and succinates; and sulphonated fatty acid salts.

Especially preferred organic builders are citrates, suitably used in amounts of from 5 to 30 wt %, preferably from 10 to 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 %.

PC3862 Builders, both inorganic and organic, are preferably present in alkali metal salt, especially sodium salt, form.

Other ingredients The detergent composition may contain crystalline or amorphous water- soluble alkali metal silicate, preferably sodium silicate having a Si02:Na2O mole ratio within the range of from 1.6:1 to 4:1, 2:1 to 3.3:1. The water- soluble silicate may suitably be present in an amount of from 1 to 20 wt %, preferably 3 to 15 wt % and more preferably 5 to 10 wt %, based on the total composition.

The compositions may also contain soil release polymers, for example, sodium carboxymethyl cellulose; sulphonated and unsulphonated PET/POET polymers, both end-capped and nonend-capped; and polyethylene glycol/polyvinyl alcohol graft copolymers such as Sokolan (Trade Mark) HP22.

The compositions may also contain dye transfer inhibiting polymers, for example, polyvinyl pyrrolidone or copolymers of vinylpyrrolidone and vinylimidazoline.

The detergent compositions may also contain one or more enzymes. Suitable enzymes include the proteases, amylases, cellulases, oxidases, peroxidases and lipases usable for incorporation in detergent compositions. Detergency enzymes are commonly employed in granular form in amounts of from about 0.1 to about 3.0 wt%. However, any suitable physical form of enzyme may be used.

PC3862 The compositions may advantageously contain a powder structurant, for example, a fatty acid (or fatty acid soap), a sugar, an acrylate or acrylate/maleate polymer, or (as previously discussed) sodium carbonate. A preferred powder structurant is fatty acid soap, suitably present in an amount of from 1 to 5 wt %.

Other materials that may be present include fluorescers; inorganic salts such as sodium sulphate; foam control agents or foam boosters as appropriate; dyes; coloured speckles; perfumes; and fabric conditioning compounds. This list is not intended to be exhaustive.

Preparation of the detergent compositions While the compositions of the invention may be prepared by any suitable process, involving spray-drying, nontower granulation or any combination of these techniques, the present invention yields especial benefits for spray-dried powders.

Inclusion of the decoupling polymer in the slurry gives, for a given slurry composition, a lower viscosity. The higher the moisture content of a slurry, the lower the viscosity, therefore the incorporation of decoupling polymer in accordance with the invention enables processable slurries of lower moisture content to be produced. Lower moisture content slurries require less energy for drying and also allow an increased rate of production through the spraydrying tower.

PC3862 EXAMPLES

The invention is further illustrated by the following nonlimiting Examples, in which parts and percentages are by 5 weight unless otherwise stated. Examples of the invention are denoted by numbers, and comparative examples by letters.

The following abbreviations are used:

LAS Linear alkylbenzene sulphonate NI Ethoxylated (7E0) C12-CI5 alcohol AO Coco dimethylamine oxide STP Sodium tripolyphosphate Sulphate Sodium sulphate Silicate Sodium alkaline silicate Carbonate Sodium carbonate Enzymes Savinase/lipolase SCMC sodium carboxymethyl cellulose EDTA ethylenediamine tetraacetic acid, tetrasodium salt NTA trisodium nitrilotriacetate A1PCS Aluminium phthalocyanine sulphonate, as Laundrosil RT granule containing 0.1 wt% active ingredient Narlex DC1 poly(lauryl methacrylate-co-acrylate) (decoupling polymer) Trade Mark, ex National Starch and Chemical Co.

PC3862 Example 1, Comparative Example A A laundry detergent powder was prepared to the following formulation by conventional spray-drying and postdosing techniques.

1 % FLA 1 S 28 [ E8 STP 8 STP 28 STP Sulphate 9.8 9.8 Silicate 9.8 Carbonate 12.4 EDTA 0.009 SCMC 1.12 Fluorescer 0.24 Water/minors to 100.0 Tergotometer tests were carried out using wash liquors (total product concentration 4 g/litre) prepared from the following:

the formulation above plus 1 wt% Narlex DC1 polymer (added from a stock solution) (Example 1); the formulation above, without polymer (Comparative Example A).

These wash liquors were compared for stain removal efficacy using tergotometer tests in which the conditions were as follows:

PC3862 Washload 40g (rust stain monitors plus clean ballast) Wash liquor volume 1 litre Liquor to cloth ratio 25:1 Wash temperature ca. ambient Water hardness 180FH Heavy metal content Zn 2.3 ppm, Fe 2.0 ppm Cu 1.1 ppm, Mn 0.12 ppm The wash procedure was as follows: 1 minute dissolution, 30 minutes soak, 15 minutes agitation at 100 rpm, two rinses. Three repeats per formulation were carried out. is Removal of the rust stain was assessed by measuring reflectance R (460 nm) before and after the wash.

Percentage stain removal was calculated as follows: 20 % stain [R (after wash) - R (before wash)] x 100 removal R (clean) - R (before wash) Values for AR and for percentage stain removal were as follows:

1 1 A Reflectance increase 19.6 15.3 JAR (460 nm) % stain removal 32.7 24.3 PC3862 Examples 2 to 5 and Comparative Examples B to D: compositions with mixed surfactant systems and containing supplementary stain removal agents 2 3 4 5 B c D LAS 22.0 22.0 22.0 22.0 24.0 24.0 24.0 NI 1.0 1.0 2.0 2.0 1.0 1.0 1.0 AO 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Narlex DC1 1.0 1.0 1.0 1.0 STP 22.0 22.0 20.0 20.0 22.0 22.0 22.0 Sulphate 16.7 15.7 16.7 15.7 15.7 13.7 14.7 Silicate 9.7 9.7 9.7 9.7 9.7 9.7 9.7 Carbonate 14.0 14.0 14.0 14.0 14.0 14.0 14.0 Enzymes 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Perfume 0.3 0.3 0.3 0.3 0.3 0.3 0.3 NTA 2.0 2.0 2.0 1.0 A1PCS 3.0 3.0 3.0 3.0 Water/ 11.4 11.4 11.4 11.4 10.4 10.4 10.4 minors - - - - - - 100.0 - - - - - - The following Table shows the amounts and ratios of LAS and cosurfactants in Examples 2 to 5 and Comparative Examples B to D: 10 1 (a) (b) Total Ratio LAS NI AO (a)+(b) (a):(b) 2, 3 22 1.0 0.5 23.5 14.7 1 4, 5 22 2.0 0.5.5 8.8 B - D 24 1 0.5 25.5 6 PC3862 Examples 6 and 7, Comparative Examples E and F: effect of decoupling polymer on slurry processing Slurries were prepared to the compositions shown in the 5 following Table (in parts by weight).

The Table also shows slurry moisture content and slurry kinematic viscosity K (measured at a shear rate of 1 s-1). The dramatic reduction of viscosity achieved by the incorporation of the decoupling polymer is readily apparent E F 6 7 LAS 2.0 24.0 22.0 22.0 NI 1.0 1.0 2.0 2.0 AO 0.5 0.5 0.5 0.5 STP 22.0 22.0 20.0 20.0 Sulphate 7.31 7.31 9.42 9.42 Silicate 9.7 9.7 9.7 9.7 Carbonate 1.35 1.35 1.24 1.24 SCMC, fluorescer 1.24 1.24 1.24 1.24 Narlex DC1 1.00 1.00 Total slurry parts 67.10 67.10 67.10 67.10 Slurry moisture content (wt%) 47.57 46.87 39.18 38.16 Kinematic viscosity K (Pa.s) 33.83 27.31 1.97 1.97 PC3862 - 19 Example 8, Comparative Example G In this example, two slurries of otherwise identical composition, one containing Narlex DCl polymer and the other without polymer, were prepared to substantially equal water contents and their viscosities measured.

8 G AS 22.0 22.0 NI 2.0 2.0 AO 0.5 0.5 STP 20.0 20.0 Sulphate 9.42 9.42 Silicate 9.7 9.7 Carbonate 1.24 1.24 SCMC 1.04 1.04 Narlex DC1 1.0 Total slurry parts 66.90 65.90 Slurry moisture content (wt%) 41.18 41.22 Kinematic viscosity K (Pa.s) 2.69 15.46 PC3862GB

Claims

1 A built particulate laundry detergent composition 5 comprising (i) from 5 to 40 wt% of a surfactant system comprising one or more anionic, nonionic, cationic, amphoteric or zwitterionic surfactants, (ii) from 10 to 80 wt% of a detergency builder, (iii) from 0.02 to 5 wt% of a decoupling polymer, (iv) other detergent ingredients to 100 wt%.

2 A detergent composition as claimed in claim 1, wherein the decoupling polymer (iii) is present in an amount of from 20 0.05 to 2 wt%.

3 A detergent composition as claimed in claim 1 or claim 2, wherein the decoupling polymer (iii) is poly(lauryl methacrylate-co-acrylate).

4 A detergent composition as claimed in any preceding claim, wherein the surfactant system (i) comprises from 10 to 30 wt%, preferably from 15 to 28 wt%, of a sulphonate or sulphate type anionic surfactant.

PC3862GB 21 - A detergent composition as claimed in claim 4, wherein the sulphonate or sulphate type anionic surfactant comprises alkylbenzene sulphonate and/or primary alcohol sulphate.

6 A detergent composition as claimed in any preceding claim, wherein the surfactant system (i) comprises (a) from 10 to 28 wt%, preferably from 12 to 25 wt%, of a 10 sulphonate or sulphate type anionic surfactant, (b) from 1 to 10 wt%, preferably from 1.5 to 8 wt%, of one or more cosurfactants selected from cationic, nonionic, amphoteric, zwitterionic or ethoxylated anionic surfactants, 15 all percentages being based on the total detergent composition.

7 A detergent composition as claimed in any preceding claim, which further comprises an effective amount of a stain removal agent selected from sequestrants, reducing bleaches, and photobleaches.

8 A detergent composition as claimed in claim 7, wherein the composition comprises nitrilotriacetic acid or a salt thereof in an amount of from 0.5 to 5 wt%.

PC3862GB 22 -

9 A detergent composition as claimed in claim 7, wherein the composition comprises sodium sulphite in an amount of from 5 to 10 wt%.

10 A detergent composition as claimed in claim 7, wherein the composition comprises aluminium. phthalocyanine sulphonate in an amount of from 0. 0005 to 0.005 wt%.

11 A built particulate laundry detergent composition substantially as hereinbefore described in any one of the Examples.

12 A process for the preparation of a built particulate laundry detergent composition as claimed in claim 1, which comprises spray-drying an aqueous slurry to form a base powder and admixing additional ingredients as necessary, wherein the decoupling polymer is incorporated via the slurry into the base powder.