TECHNICAL FIELD

The present invention relates to a bleaching detergent composition containing crystalline alkali metal aluminosilicate (zeolite) as a detergency builder, and also including a bleach system comprising a peroxyacid.

BACKGROUND AND PRIOR ART

The ability of crystalline alkali metal aluminosilicate (zeolite) to sequester calcium ions from aqueous solution has led to its becoming a well-known replacement for phosphates as a detergency builder. Particulate detergent compositions containing zeolite are widely disclosed in the art, for example, in GB 1 473 201 (Henkel) , and are sold commercially in many parts of Europe, Japan and the United States of America.

Although many crystal forms of zeolite are known, the preferred zeolite for detergents use has always been zeolite A: other zeolites such as X or P(B) have not found favour because their calcium ion uptake is either inadequate or too slow. Zeolite A has the advantage of being a "maximum aluminium" structure containing the maximum possible proportion of aluminium to silicon or the theoretical minimum Si:Al ratio of 1.0 - so that its capacity for taking up calcium ions from aqueous solution is intrinsically greater than those of zeolite X and P which generally contain a lower proportion of aluminium (or a higher Si:Al ratio) .

EP 384 070A (Unilever) describes and claims a novel zeolite P (maximum aluminium zeolite P, or zeolite MAP) having an especially low silicon to aluminium ratio, not greater than

1.33 and preferably not greater than 1.15. This material is demonstrated to be a more efficient detergency builder than conventional zeolite 4A.

EP 448 297A and EP 502 675A (Unilever) disclose detergent formulations containing zeolite MAP with a cobuilder (citrate or polymer) , and also containing sodium perborate onohydrate bleach and TAED bleach precursor. Compositions containing zeolite MAP exhibit better detergency than corresponding compositions containing zeolite 4A.

It has now been discovered that replacement of zeolite A by zeolite MAP gives an additional benefit in detergent powders having a bleach system based on an organic peroxyacid: the stability of the peroxyacid on storage is significantly increased. This is surprising because the water content of zeolite MAP is not significantly lower than that of zeolite A.

DEFINITION OF THE INVENTION

The present invention provides a particulate bleaching detergent composition comprising:

(a) one or more detergent-active compounds,

(b) one or more detergency builders including alkali metal aluminosilicate, and

(c) a bleach system comprising an organic peroxyacid,

wherein the alkali metal aluminosilicate comprises zeolite P having a silicon to aluminium ratio not greater than 1.33 (zeolite MAP).

A further subject of the invention is the use of zeolite MAP to improve the stability of an organic peroxyacid in a particulate bleaching detergent composition, especially one having a bulk density of 700 g/litre or above.

DETAILED DESCRIPTION OF THE INVENTION

The subject of the invention is a particulate bleaching detergent composition containing detergent-active compounds, a builder system based on zeolite MAP, and a bleaching system containing an organic peroxyacid. These are the essential elements of the invention; other optional detergent ingredients may also be present as desired or required.

A preferred detergent composition in accordance with the invention comprises:

(a) from 5 to 60 wt% of one or more detergent-active compounds,

(b) from 10 to 80 wt%, preferably from 15 to 80 wt%, of one or more detergency builders, including zeolite MAP,

(c) a bleach system comprising from 2 to 10 wt% of an organic peroxyacid,

(d) optionally other detergent ingredients to 100 wt%,

all percentages being based on the detergent composition.

The detergent-active compound

The detergent compositions of the invention 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 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 alkyl sulphates, particularly ^C ₁ "" ₁₅ P ^r i ^mar Y 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 C aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol, and more especially the C. C primary and secondary aliphatic alcohols ethoxylated with an average of from 1 to 10 moles of ethylene oxide per mole of alcohol.

Also of interest are non-ethoxylated nonionic surfactants, for example, alkylpolyglycosides;

O-alkanoyl glucosides as described in EP 423 968A (Unilever) ; and polyhydroxyamides (gluca ide) as described, for example, in WO 92 06162A (Procter & Gamble) .

The choice of detergent-active compound (surfactant) , and the amount present, will depend on the intended use of the detergent composition: different surfactant systems may be chosen, as is well known to the skilled formulator, for handwashing products and for products intended for use in different types of washing machine.

The total amount of surfactant present will also depend on the intended end use, but will generally range from 5 to 60 wt%, preferably from 5 to 40 wt%.

Detergent compositions suitable for use in most automatic fabric washing machines generally contain anionic non-soap surfactant, or nonionic surfactant, or combinations of the two in any ratio, optionally together with soap.

The detergency builder system

The detergent compositions of the invention also contains one or more detergency builders. The total amount of detergency builder in the compositions will suitably range from 10 to 80 wt%.

The detergency builder system of the compositions of the invention is based on zeolite MAP, optionally in conjunction with one or more supplementary builders. The amount of zeolite MAP present may suitably range from 5 to 60 wt%, but is preferably at least 15 wt%, more preferably from 15 to 60 wt% and advantageously from 15 to 45 wt%, all percentages being on an anhydrous basis (see below) .

Preferably, the alkali metal aluminosilicate present in the compositions of the invention consists substantially wholly of zeolite MAP.

Zeolite MAP

Zeolite MAP (maximum aluminium zeolite P) and its use in detergent compositions are described and claimed in EP 384 070A (Unilever) . It is defined as an alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not greater than 1.33, preferably within the range of from 0.9 to 1.33, and more preferably within the range of from 0.9 to 1.2.

Of especial interest is zeolite MAP having a silicon to aluminium ratio not greater than 1.15; and zeolite MAP having a silicon to aluminium ratio not greater than 1.07 is especially preferred.

Although zeolite MAP like other zeolites contains water of hydration, for the purposes of the present invention amounts and percentages of zeolite are generally expressed in terms of the notional anhydrous material. The amount of water present in hydrated zeolite

MAP at ambient temperature and humidity is normally about 20 wt%.

Zeolite MAP generally has a calcium binding capacity of at least 150 mg CaO per g of anhydrous aluminosilicate, as measured by the standard method described in GB 1 473 201 (Henkel) and also described, as "Method I", in EP 384 070A (Unilever) . The calcium binding capacity is normally at least 160 mg CaO/g and may be as high as 170 mg CaO/g. Zeolite MAP also generally has an "effective calcium binding capacity", measured as described under "Method II" in

EP 384 070A (Unilever) , of at least 145 mg CaO/g, preferably at least 150 mg CaO/g.

Particle size of the zeolite MAP

Preferred zeolite MAP for use in the present invention is especially finely divided and has a d _5Q (as defined below) within the range of from 0.1 to 5.0 micrometres, more preferably from 0.4 to 2.0 micrometres and most preferably from 0.4 to 1.0 micrometres.

The quantity "d ₅₀ " indicates that 50 wt% of the particles have a diameter smaller than that figure, and there are corresponding quantities "d _a ", "d _go " etc.

Especially preferred materials have a d _Q yu_ below

3 micrometres as well as a ds _CΛ o below 1 micrometre.

Various methods of measuring particle size are known, and all give slightly different results. In the present specification, the particle size distributions and average values (by weight) quoted were measured by means of a Malvern Mastersizer (Trade Mark) with a 45 mm lens, after dispersion in demineralised water and ultrasonification for 10 minutes.

Advantageously, but not essentially, the zeolite MAP may have not only a small average particle size, but may also contain a low proportion, or even be substantially free, of large particles. Thus the particle size distribution may advantageously be such that at least 90 wt% and preferably at least 95 wt% are smaller than 10 micrometres; at least 85 wt% and preferably at least 90 wt% are smaller than 6 micrometres; and at least 80 wt% and preferably at least 85 wt% are smaller than 5 micrometres.

Other builders

The zeolite MAP may, if desired, be used in conjunction with other inorganic or organic builders. However, the presence of significant amounts of zeolite A is not preferred.

Inorganic builders that may be present include sodium carbonate, if desired in combination with a crystallisation seed for calcium carbonate, as disclosed in GB 1 437 950 (Unilever) . Organic builders that may be present include polycarboxylate polymers such as polyacrylates, acrylic/maleic copoly ers, and acrylic phosphinates; monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxy alonates, dipicolinates, hydroxyethyliminodiacetates, alkyl- and alkenylmalonates and succinates; and sulphonated fatty acid salts. This list is not intended to be exhaustive.

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

Preferred supplementary builders for use in conjunction with zeolite MAP include citric acid salts, more especially sodium citrate, suitably used in amounts of from 3 to 35 wt%, more preferably from 5 to 30 wt%. This builder combination is described and claimed in EP 448 297A (Unilever) .

Also preferred are polycarboxylate polymers, more especially acrylic/maleic copolymers, suitably used in amounts of from 0.5 to 15 wt%, especially from 1 to 10 wt%, of the detergent composition; this builder combination is described and claimed in EP 502 675A (Unilever) .

The bleach system

Detergent compositions according to the invention contain a bleach system, which contains as an essential ingredient an organic peroxyacid.

Organic peroxyacids normally have the general formula:

HOO C II R—Y

wherein R is an alkylene or substituted alkylene group containing form 1 to 20 carbon atoms, optionally having an internal amide linkage; or a phenylene or substituted phenylene group; and Y is hydrogen, halogen, alkyl, aryl, an imido-aromatic or non-aromatic group, a carboxylic acid or percarboxylic acid group, or a quaternary ammonium group.

Typical monoperoxyacids useful in the compositions of the invention include, for example:

(i) peroxybenzoic acid and ring-substituted peroxybenzoic acids, eg peroxy-alpha-naphthoic acid;

(ii) aliphatic, substituted aliphatic and arylalkyl monoperoxyacids, eg peroxylauric acid, peroxystearic acid and N,N'-phthaloylaminoperoxy caproic acid (PAP) ;

(iϋ) 6-octylamino-6-oxoperoxyhexanoic acid.

Especially preferred from this group is N,N'-phthaloylaminoperoxy caproic acid (PAP) .

Typical aliphatic or aromatic diperoxyacids useful in the compositions of the invention include, for example:

(iv) 1,12-diperoxydodecanedioic acid (DPDA) ; ^•

(v) 1,9-diperoxyazelaic acid;

(vi) diperoxybrassilic acid, diperoxysebacic acid and diperoxyisophthalic acid;

(vii) 2-decyldiperoxybutane-l,4-dioic acid; and

(viii) 4,4'-sulphonylbisperoxybenzoic acid.

Especially preferred from this group is 1,12-diperoxydodecanedioic acid (DPDA).

The organic peroxyacid is suitably used in an amount within the range of from 2 to 10 wt%, preferably from 4 to 8 wt%.

Other ingredients

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; pigments; and perfumes. This list is not intended to be exhaustive.

Bulk density

Particulate detergent compositions of the invention preferably have a bulk density of at least 500 g/1, more preferably at least 700 g/1, and most preferably at least 800 g/1. The benefits of the invention are especially applicable to high bulk density compositions, in which the storage stability of sensitive ingredients is generally more problematic than in less, dense powders.

Preparation of the detergent compositions

The particulate detergent compositions of the invention may be prepared by any suitable method.

One suitable method comprises spray-drying a slurry of compatible heat-insensitive ingredients, including the zeolite MAP, any other builders, and at least part of the detergent-active compounds: and subsequently spraying on or postdosing those ingredients unsuitable for processing via the slurry, including the peroxyacid and any other bleach ingredients. In a preferred variant of this process, a high bulk density powder may be produced by densifying the spray-dried base powder in a batch or continuous high-speed mixer/granulator before addition of the postdosed ingredients.

High bulk density powders may also be prepared by wholly non-tower routes. In another method, especially preferred, a high bulk density base powder is prepared directly from its constituent raw materials, by mixing and granulating in a high-speed mixer/granulator, and then postdosing bleach and other ingredients as in the spray-drying/post-tower densification route.

Processes using high-speed ixer/granulators are disclosed, for example, in EP 340 013A, EP 367 339A, EP 390 251A and EP 420 317A (Unilever) .

EXAMPLES

The invention is further illustrated by the following Examples, in which parts and percentages are by weight unless otherwise indicated. Examples identified by numbers are in accordance with the invention, while those identified by letters are comparative.

The zeolite MAP used in the Examples was prepared by a method similar to that described in Examples 1 to 3 of EP 384 070A (Unilever) . Its silicon to aluminium ratio was 1.07. Its particle size (d _5Q ) as measured by the Malvern Mastersizer was 0.8 micrometres.

The zeolite A used was Wessalith (Trade Mark) P powder ex Degussa.

The anionic surfactant used was coconut alcohol sulphate (cocoPAS) ex Philippine Refining Co..

The nonionic surfactants used were Synperonic (Trade Mark) A7 and A3 ex Id, which are C ₁₂ -C _ alcohols ethoxylated respectively with an average of 7 and 3 moles of ethylene oxide.

Example 1. Comparative Example A

Detergent base powders were prepared to the formulations given below (in parts by weight) , by mixing and granulating in a Fukae (Trade Mark) FS-30 batch- high-speed mixer/granulator.

CocoPAS

Nonionic surfactant 7E0

Nonionic surfactant 3E0 Zeolite 4A (as anhydrous*)

Zeolite MAP (as anhydrous*)

Sodium carbonate

SCMC

Fluorescer Moisture (nominal)

48.96 66.46

Bulk density (g/1) 808 816

*The zeolites were used in hydrated form, but the amounts are quoted in terms of anhydrous material, the water of hydration being included in the amount shown for total moisture.

The actual moisture contents of the base powders were determined by measuring weight loss after heating to 135°C for 1 hour, and were found to be as follows:

Moisture (wt%) 8.6 6.5

Thus the base powder containing zeolite MAP had a slightly higher moisture content.

Powder samples were prepared by mixing 1.4 g of DPDA granules with 8.6 g of each base powder. The composition (weight percent) of the DPDA granules was as follows:

DPDA 22

Dodecanedioic acid 1 Polyacrylic acid 1 Sodium sulphate 1

Each powder therefore contained 14 wt% of DPDA granules, equivalent to 3.1 wt% of DPDA itself.

The products were stored in open bottles at 28 C and 70% relative humidity. Storage stabilities were assessed by removing samples at different time intervals and determining residual peracid by titrating with chloroform/sodium thiosulphate.

The results, expressed as percentages of the initial value, were as follows:

Storage time (days)

0 7

14 28

Example 2, Comparative Example B

The procedure of Examples 1 and A was repeated using different storage conditions: sealed bottles at 37 C. The powder of Example 2 had the same composition as- the powder of Example 1, and the powder of Comparative Example B had the same composition as the powder of Comparative Example A.

The results were as follows:

Storage time (days)

0

7 14 28

Both these Examples show that the peracid stability was better in the zeolite-MAP-containing powder despite its higher moisture content..

Example 3, Comparative Example C

Detergent base powders were prepared to the formulations given below (in parts by weight) , by mixing and granulating in a Fukae (Trade Mark) FS-30 batch high-speed mixer/granulator.

CocoPAS

Nonionic surfactant 7E0

Nonionic surfactant 3E0 Soap

Zeolite 4A (as anhydrous)

Zeolite MAP (as anhydrous)

Sodium carbonate

Moisture (nominal)

50.20 66.00

Bulk density (g/1) 841 850

Powder samples were prepared by mixing 0.5 g of PAP granules ex Hoechst (66.7 wt% PAP, 32.3 wt% inert carrier) with 9.5 g of each base powder. Each powder therefore contained 5 wt% of PAP granules, equivalent to 3.33 wt% of PAP itself.

The products were stored in sealed bottles at 37 C. Storage stabilities were assessed by removing samples at different time intervals and determining residual peracid by titration with sodium thiosulphate.

The results, expressed as percentages of the initial value, were as follows:

Storage time (days)

0

7

28