Detergent compositions

Abstract

 A particulate detergent composition of high bulk density comprises a non-spray-dried homogeneous particulate base powder and other ingredients in the form of separate particles or granules, the other ingredients including from 0.5 to 10 wt% of separate granules of a polycarboxylate polymer, for example, an acrylic/maleic copolymer. The separate polymer granules preferably have an average particle size of at least 300 µm, a bulk density of at least 500 g/litre, and comprise at least 80 wt% polymer.

Description

TECHNICAL AREA

[0001] The present invention relates to particulate detergent compositions of high bulk density and improved detergency performance, containing polycarboxylate, preferably acrylic or acrylic/maleic, polymers.

BACKGROUND AND PRIOR ART

[0002] The inclusion of polycarboxylate polymers, for example, acrylic and acrylic/maleic copolymers, in particulate detergent compositions is well-known. These polymers fulfil a number of functions which include detergency building (sequestration of hardness ions such as calcium and magnesium), reduction of soil redeposition, and particle binding.

[0003] Acrylic/maleic copolymers suitable for inclusion in detergent compositions are disclosed in EP 25 551B (BASF) and are commercially available as Sokalan (Trade Mark) CP5 and CP7. Polyacrylates are also available from the same manufacturer, for example, Sokalan PA25. The polymers are available in aqueous solution form and also as powders and granules.

[0004] Formulators of detergent powders conventionally make a distinction between the base powder and post-dosed (admixed, post-added) ingredients. The base powder contains most or all of the detergent-active compounds (surfactants) and detergency builders present, and the term indicates a substantially homogeneous material composed of substantially uniform identically composed granules.

[0005] In traditional powders of low or medium bulk density the base powder is generally prepared by spray-drying an aqueous slurry of the ingredients. In the compact powders of high bulk density that are currently favoured, the base powder may be prepared by mixing and granulation in a high-speed mixer/granulator. Other granulation and drying processes are well known to the detergents formulator.

[0006] Normally any ingredients that are sufficiently robust and stable to processing at elevated temperatures are included in the base powder together with the surfactants and builders. Such ingredients include soap, fluorescers, cellulosic antiredeposition agents, sodium silicate, sodium carbonate, and acrylic or acrylic/maleic polymers. The polymers are normally incorporated in aqueous solution form and are useful as binders as well as improving detergency and soil redeposition.

[0007] Ingredients that are sensitive to moisture or to elevated temperatures are postdosed to the base powder and, if particulate, remain as separate, discrete particles in the final product. Peroxy bleach compounds such as persalts and peroxyacids, bleach activators, enzymes, foam control compounds and perfumes are normally postdosed. Salts such as sodium carbonate, sodium sulphate and sodium citrate are sometimes postdosed rather than, or as well as, incorporated in the base powder.

[0008] The present invention is based on the discovery that, in powders of high bulk density containing alkali metal aluminosilicate builder, acrylic and acrylic/maleic copolymers such as Sokalan CP5 and CP7 provide more effective detergency building when postdosed in granular form then when incorporated in the base powder; and that, when a peroxy bleach compound, notably sodium percarbonate, is also postdosed, enhanced bleach stability is observed.

[0009] In their brochure for the Sokalan polymers, the manufacturers BASF state that these polymers in granule form are of high bulk density and are especially suitable for powder blending processes. They may be added to spray-dried (base) powders after drying; or may be blended with other powder components of detergents mixed in a rotary agglomerator. The latter process gives powders mostly of bulk density about 500 g/litre.

[0010] There is no suggestion that these polymers may be postdosed to a preformed homogeneous non-spray-dried detergent base powder of high bulk density to provide more effective detergency building and to improve bleach stability.

DEFINITION OF THE INVENTION

[0011] The present invention accordingly provides a particulate detergent composition of high bulk density comprising:

(i) from 40 to 90 wt% of a non-spray-dried homogeneous particulate base powder having a bulk density of at least 600 g/litre, comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder,

(ii) from 0.5 to 10 wt% of separate granules of a polycarboxylate polymer, and optionally

(iii) other ingredients in the form of separate particles or granules, to 100 wt%,

all percentages being based on the total detergent composition.

[0012] In a preferred embodiment of the invention, the other ingredients (iii) comprise a peroxy bleach compound in an amount of from 5 to 35 wt%.

[0013] The invention further provides the use of a polycarboxylate polymer in an amount of from 0.5 to 10 wt%, in the form of separate granules, in admixture with from 40 to 90 wt% of separate granules of a non-spray-dried homogeneous detergent base powder having a bulk density of at least 600 g/litre and comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder, all percentages being based on the total detergent composition, to improve detergency performance.

[0014] The invention also provides the use of a polycarboxylate polymer in an amount of from 0.5 to 10 wt%, in the form of separate granules, in admixture with from 40 to 90 wt% of separate granules of a non-spray-dried homogeneous detergent base powder having a bulk density of at least 600 g/litre and comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder, and in admixture with from 5 to 35 wt% of separate particles or granules of a peroxy bleach compound, all percentages being based on the total detergent composition, to improve detergency performance and to increase the stability of the peroxy bleach compound.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The detergent compositions of the present invention are particulate compositions of high bulk density, at least 600 g/litre, preferably at least 650 g/litre, and more preferably at least 700 g/litre.

[0016] They are composed of at least two different discrete granules: the base powder, and the postdosed polymer granules. Further postdosed particulate materials may also be present, notably peroxy bleach compounds.

The detergent base powder

[0017] The detergent base powder contains, as essential ingredients, detergent-active compounds (surfactants) and alkali metal aluminosilicate detergency builder.

[0018] The detergent-active compounds 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 preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds.

[0019] 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.

[0020] 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-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).

[0021] The preferred surfactant system for the compositions of the invention comprises one or more anionic sulphonate or sulphate type surfactants, in combination with one or more nonionic surfactants, optionally in conjunction with a minor amount of soap. Especially preferred surfactant systems comprise alkylbenzene sulphonate and/or primary alcohol sulphate in combination with ethoxylated alcohol nonionic surfactant.

[0022] The total amount of surfactant present ranges from 5 to 50 wt% (based on the whole product including postdosed ingredients), preferably from 10 to 30 wt% and more preferably from 15 to 25 wt%.

[0023] The base powder also contain one or more detergency builders. The total amount of detergency builder in the compositions will suitably range from 10 to 90 wt%, preferably from 10 to 60 wt%.

[0024] The builder system consists wholly or partially of an alkali metal aluminosilicate. This is present in an amount of from 10 to 80 wt% (based on the anhydrous material), preferably from 10 to 60% by weight and more preferably from 25 to 50 wt%.

[0025] The alkali metal aluminosilicate may be either crystalline or amorphous or mixtures thereof, having the general formula:

[0026] These materials contain some bound water and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates contain 1.5-3.5 SiO₂ units (in the formula above). Both the amorphous and the crystalline materials can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature.

[0027] Suitable crystalline sodium aluminosilicate ionexchange detergency builders are described, for example, in GB 1 473 201 (Henkel) and GB 1 429 143 (Procter & Gamble). The preferred sodium aluminosilicates of this type are the well-known commercially available zeolites A and X, and mixtures thereof.

[0028] The zeolite may be the commercially available zeolite 4A now widely used in laundry detergent powders. However, advantageously, the zeolite builder incorporated in the compositions of the invention is maximum aluminium zeolite P (zeolite MAP) as described and claimed in EP 384 070B (Unilever). Zeolite MAP is defined as an alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not exceeding 1.33, preferably not exceeding 1.15. Especially preferred is zeolite MAP having a silicon to aluminium ratio not exceeding 1.07, more preferably about 1.00. The calcium binding capacity of zeolite MAP is generally at least 150 mg CaO per g of anhydrous material.

[0029] Supplementary builders may also be present in the base powder, as well as the polycarboxylate polymers which are postdosed. These include 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. This list is not intended to be exhaustive.

[0030] Especially preferred organic builders are citrates, suitably used in amounts of from 5 to 30 wt%, preferably from 10 to 25 wt%.

[0031] Builders, both inorganic and organic, are preferably present in alkali metal salt, especially sodium salt, form.

[0032] Other ingredients that may be present in the detergent base powder include fluorescers, inorganic salts, cellulosic antiredeposition agents, and water. This list is not intended to be exhaustive.

The polycarboxylate polymer

[0033] The polycarboxylate polymers which are present in the compositions of the present invention as separate granules are preferably polymers of unsaturated monocarboxylic acids and/or unsaturated dicarboxylic acids. Suitable monocarboxylic monomers include acrylic, methacrylic, vinylacetic, and crotonic acids; suitable dicarboxylic monomers include maleic, fumaric, itaconic, mesaconic and citraconic acids and their anhydrides. The polymers may also contain units derived from non-carboxylic monomers, preferably in minor amounts. The polymers may be in acid, salt or partially neutralised form.

[0034] Especially preferred are homopolymers of acrylic acid and copolymers of acrylic and maleic acids. Especially preferred are the acrylic/maleic copolymers available from BASF as Sokalan (Trade Mark) CP5 and CP7 (salt form) and CP45 (acid form).

[0035] The postdosed polymer is preferably in the form of granules having an average particle size of at least 300 µm and preferably at least 400 µm. Most preferably the polymer granules have an average particle size within the range of from 400 to 800 µm.

[0036] The polymer granules suitably have a bulk density of at least 400 g/litre and preferably at least 500 g/litre.

[0037] The granules preferably comprise at least 80 wt%, more preferably at least 90 wt%, of polymer. As previously indicated, Sokalan CP5, CP7 and CP45 are available as approximately 90-95 wt% active granules of bulk density in the 550-650 g/litre range which are highly suitable for use in the present invention. These granules may be distinguished from the powder form also available, unsuitable for use in the present invention, of which typically 99 wt% has a particle size less than 400 µm and 75 wt% has a particle size less than 180 µm; while the granules generally contain less than 2 wt% of material having a particle size of 180 µm or less.

[0038] The polymer present as separate (postdosed) granules amounts to from 0.5 to 10 wt% of the composition, and preferably from 1 to 8 wt%.

[0039] If desired, polymer may additionally be present in the base powder where its presence aids powder structuring. This polymer will generally be introduced in aqueous solution form, not granular form.

Bleaching ingredients

[0040] According to a preferred embodiment of the invention, the compositions contain a peroxy bleach compound, for example, an inorganic persalt or organic peroxyacid, capable of yielding hydrogen peroxide in aqueous solution.

[0041] 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 include sodium perborate monohydrate and tetrahydrate. However, the most preferred peroxy bleach compound is sodium percarbonate.

[0042] The peroxy bleach compound is suitably present in an amount of from 5 to 35 wt%, preferably from 10 to 25 wt%.

[0043] 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%.

[0044] 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 in 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, in particular cholyl-4-sulphophenyl carbonate. Also of interest are peroxybenzoic acid precursors, in particular,N,N,N-trimethylammonium toluoyloxy benzene sulphonate; and the cationic bleach precursors disclosed in EP 284 292A and EP 303 520A (Kao).

[0045] A bleach stabiliser (heavy metal sequestrant) may also be present. Suitable bleach stabilisers include ethylenediamine tetraacetate (EDTA) and the polyphosphonates such as ethylenediamine tetramethylene phosphonate (EDTMP) or diethylenetriamine pentamethylene phosphonate (DETPMP).

[0046] An especially preferred bleach system comprises a peroxy bleach compound, preferably sodium percarbonate, together with a bleach activator, preferably TAED, and a polyphosphonate bleach stabiliser.

Other ingredients

[0047] The compositions of 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%, and may be incorporated in the base powder, postdosed as separate particles or granules, or both.

[0048] Compositions of the invention may also contain soil release polymers, for example, the so-called PET/POET polymers comprising units of ethylene terephthalate and polyoxyethylene terephthalate; or the polyethylene oxide/polyvinyl acetate graft copolymer available commercially from BASF as Sokalan (Trade Mark) HP22.

[0049] The base powder may incorporate a small amount of a powder structurant, for example, a fatty acid (or fatty acid soap), a sugar, or sodium silicate. As previously indicated, polycarboxylate polymers may also be present in the base powder, in addition to the polymer present as postdosed particles or granules, in order to aid structuring. One preferred powder structurant is fatty acid soap, suitably present in an amount of from 1 to 5 wt%.

[0050] Other materials that may be present in detergent compositions of the invention include sodium silicate; antiredeposition agents such as cellulosic polymers; fluorescers; inorganic salts such as sodium sulphate; lather control agents or lather boosters as appropriate; proteolytic and lipolytic enzymes; dyes; coloured speckles; perfumes; foam controllers; and fabric softening compounds.

Preparation of the detergent compositions

[0051] The particulate detergent compositions of the invention are of high bulk density and are composed of a base powder and postdosed granular or particulate ingredients.

[0052] The base powder may be prepared by any method that yields substantially homogeneous granules of high bulk density. This may be achieved by post-tower densification of a spray-dried powder, or, preferably, by a wholly non-tower (non-spray-drying) process in which liquid and solid ingredients are mixed and granulated together. In both cases a high-speed mixer/granulator having both a stirring and a cutting action may advantageously be used.

[0053] The high-speed mixer/granulator, also known as a high-speed mixer/densifier, may be a batch machine such as the Fukae (Trade Mark) FS, or a continuous machine such as the Lödige (Trade Mark) Recycler CB30. Suitable processes are described, for example, in EP 340 013A, EP 367 339A, EP 390 251A, EP 420 317A, EP 506 184A and EP 544 492A (Unilever).

[0054] Liquid ingredients unsuitable for incorporation in the base powder, for example, mobile ethoxylated nonionic surfactants and perfume may be sprayed on or otherwise mixed into the base powder.

[0055] Finally, the polymer granules, bleach ingredients (bleaches, bleach precursor, bleach stabilisers), proteolytic and lipolytic enzymes, coloured speckles, perfumes, foam control granules and any other granular or particulate ingredients not included in the base powder are incorporated by dry mixing.

EXAMPLES

[0056] The invention will be further illustrated by the following Examples, in which parts and percentages are by weight unless otherwise indicated.

[0057] Additional information on some ingredients used in the Examples is as follows:

NaLAS:

linear alkylbenzene sulphonate, sodium salt

NaPAS:

primary alcohol sulphate, sodium salt

Acrylic/maleic copolymer:

Sokalan CP5 or CP7 ex BASF

TAED:

tetraacetylethylenediamine

EDTMP:

ethylenediamine tetramethylene phosphonate

Zeolite 4A:

Wessalith (Trade Mark) ex Degussa

Zeolite MAP:

as described and claimed in EP 384 070B (Unilever): Doucil (Trade Mark) A24 ex Crosfield Chemicals.

Example 1

[0058] A detergent powder of high bulk density was prepared to the formulation shown below. The base powder was prepared by mixing and granulation in a Lödige Recycler high-speed mixer/granulator, and the remaining ingredients were postdosed.

[0059] 

	Base	Whole powder
NaLAS	12.39	8.46
Nonionic surfactants	10.05	6.87
Na soap	1.62	1.10
Zeolite 4A (anhydrous basis)	41.89	28.60
Zeolite MAP (anhydrous basis)	4.77	3.26
Acrylic/maleic copolymer	1.35	0.93
Sodium carbonate	11.62	7.93
Sodium carboxymethylcellulose	0.75	0.52
Minor ingredients and water	15.56	10.62
Total base powder	100.00	68.29
Sodium perborate tetrahydrate		8.00
Sodium perborate monohydrate		8.00
TAED (83% active)		6.00
EDTMP (34% active)		0.63
Antifoam granule		2.50
Sodium carbonate		2.91
Enzymes		1.67
Perfume		0.50
Acrylic/maleic polymer granules		1.50
Total		100.00

[0060] The postdosed polymer granules had an average particle size of 450-720 µm and a bulk density of 570 g/litre.

[0061] The bulk density of the base powder was 900 g/litre and the bulk density of the final product was 835 g/litre.

[0062] The powder showed excellent detergency and improved stability of the sodium perborate-based bleach system.

Example 2

[0063] A high bulk density detergent powder containing a sodium percarbonate bleach system was prepared to the formulation given below, by the processes described in Example 1.

[0064] 

	Base	Whole powder
NaPAS	21.85	12.00
Nonionic surfactants	10.92	6.00
Na soap	3.42	1.88
Zeolite MAP (anhydrous basis)	42.27	23.22
Sodium citrate	6.16	3.38
Sodium carbonate	4.34	2.38
Sodium carboxymethylcellulose	1.69	0.93
Minor ingredients and water	9.35	5.14
Total base powder	100.00	54.93
Sodium percarbonate		19.00
TAED (83% active)		5.50
EDTMP (34% active)		0.42
Antifoam granule		3.78
Sodium carbonate		7.37
Sodium bicarbonate		1.00
Sodium disilicate (granular)		3.00
Enzymes		1.55
Perfume		0.45
Acrylic/maleic polymer granules		3.00
Total		100.00

[0065] The postdosed polymer granules had an average particle size of 420-720 µm and a bulk density of 570 g/litre.

[0066] The bulk density of the base powder was 914 g/litre and the bulk density of the final product was 853 g/litre.

[0067] The powder showed excellent detergency and improved stability of the sodium percarbonate-based bleach system.

Claims

1. A particulate detergent composition of high bulk density comprising a non-spray-dried homogeneous particulate base powder and other ingredients in the form of separate particles or granules, and including a polycarboxylate polymer, characterised in that it comprises:

(i) from 40 to 90 wt% of a non-spray-dried homogeneous particulate base powder having a bulk density of at least 600 g/litre, comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder,

(ii) from 0.5 to 10 wt% of separate granules of a polycarboxylate polymer, and optionally

(iii) other ingredients in the form of separate particles or granules, to 100 wt%,

all percentages being based on the total detergent composition.

2. A detergent composition as claimed in claim 1, characterised in that the polymer (ii) is an acrylate/maleate copolymer.

3. A detergent composition as claimed in any preceding claim, characterised in that it comprises from 1 to 8 wt% of the polymer (ii).

4. A detergent composition as claimed in any preceding claim, characterised in that the polymer granules have an average particle size of at least 300 µm.

5. A detergent composition as claimed in any preceding claim, characterised in that the polymer granules have a bulk density of at least 500 g/litre.

6. A detergent composition as claimed in any preceding claim, characterised in that the polymer granules comprise at least 80 wt% polymer.

7. A detergent composition as claimed in any preceding claim, characterised in that the other ingredients (iii) comprise a peroxy bleach compound in an amount of from 5 to 35 wt%.

8. A detergent composition as claimed in claim 7, characterised in that the peroxy bleach compound comprises sodium percarbonate.

9. Use of a polycarboxylate polymer in an amount of from 0.5 to 10 wt%, in the form of separate granules, in admixture with from 40 to 90 wt% of separate granules of a non-spray-dried homogeneous detergent base powder having a bulk density of at least 600 g/litre and comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder, all percentages being based on the total detergent composition, to improve detergency performance.

10. Use of a polycarboxylate polymer in an amount of from 0.5 to 10 wt%, in the form of separate granules, in admixture with from 40 to 90 wt% of separate grnaules of a non-spray-dried homogeneous detergent base powder having a bulk density of at least 600 g/litre and comprising from 5 to 50 wt% of one or more detergent-active compounds and from 10 to 80 wt% of an alkali metal aluminosilicate builder, and in admixture with from 5 to 35 wt% of separate particles of a peroxy bleach compound, all percentages being based on the total detergent composition, to improve detergency performance and to increase the stability of the peroxy bleach compound.