WO1994001521A1

WO1994001521A1 - Process of dispensing a high bulk density percarbonate-containing laundry detergent

Info

Publication number: WO1994001521A1
Application number: PCT/US1993/006302
Authority: WO
Inventors: Gerald Marcel Baillely; Carolyn Jayne Brown; Graham Alexander Sorrie
Original assignee: The Procter & Gamble Company
Priority date: 1992-07-14
Filing date: 1993-07-02
Publication date: 1994-01-20
Also published as: DE69331905T2; EP0650518A4; EP0650518B1; CA2140286C; MA22930A1; GB9214890D0; CA2140286A1; MX9304262A; ATE217341T1; DE69331905D1; JPH07509281A; ES2176205T3; EP0650518A1; EG20548A

Abstract

A low temperature process for washing laundry in a domestic washing machine is provided. In this process a detergent composition of bulk density > 650 g/litre is delivered to the wash via a dispensing device. The detergent composition comprises a bleach activator and a coated alkali metal percarbonate bleach wherein the coating material is a mixed salt of an alkali metal carbonate and alkali metal sulphate. The washing process is conducted at a temperature of no more than 50 °C.

Description

PROCESS OF DISPENSING A HIGH BULK DENSITY PERCARBONATE- CONTAINING LAUNDRY DETERGENT.

This invention relates to a low temperature process for washing laundry in a domestic washing machine, and more especially to such a process wherein a high density detergent composition comprising a carbonate/sulphate coated alkali metal percarbonate salt and a bleach activator is delivered to the wash via a dispensing device.

Considerable interest exists in the development of more 'environmentally friendly' processes for washing laundry in the home. The term, 'environmentally friendly¹ as applied to such processes has many connotations, but will include those wash processes which consume less energy, principally by operating at lower temperatures, and those which utilize detergent compositions containing fewer environmentally negative components. These detergent compositions also preferably are of the so- called, 'compact' type characterised in that they are of higher densities and contain lower amounts of filler salts than conventional laundry detergent products.

The inorganic perhydrate bleach most widely used in laundry detergent compositions is sodium perborate in the form of either the monohydrate of tetrahydrate. However, concerns about the impact of boron salts on the environment have led to an increasing interest in other perhydrate salts, of which sodium percarbonate is the most readily available.

Detergent compositions containing sodium percarbonate are known in the art. Sodium percarbonate is an attractive perhydrate for use in detergent compositions because it dissolves readily in water, is weight efficient and. after giving up its available oxygen, provides a useful source of carbonate ions for detergency purposes.

The inclusion of percarbonate salts in laundry detergent compositions has been restricted hitherto by the relative instability of the bleach. In particular, percarbonate salts decompose rapidly when stored in a moist and/or warm atmsophere. It is known that acceptable storage characteristics may however be obtained through the protection of the carbonate by coating the crystalline product, or by the inclusion of stabilizing agents during its manufacture, or both. A variety of suitable coating agents have been proposed including silicates and mixtures of inorganic sulphate and carbonate salts.

Whilst coating of the percarbonate bleach improves its storage stability the presence of the coating may act so as to inhibit the performance of the bleach, particularly when used in low temperature washing processes. This is one reason which accounts for the fact that coated percarbonate bleaches have not found widespread use as replacements for perborate bleaches in detergent products.

The Applicants have however unexpectedly discovered that when a detergent composition comprising a percarbonate bleach coated with a mixed carbonate/sulphate salt in combination with a bleach activator is used in a low temperature washing process, whereby this composition is delivered to the wash liquor via a dispensing device, that comparable cleaning performance is obtained to the equivalent process in which a perborate bleach is used. The use of such dispensing devices is known to prove transient high localised concentrations at the start of the wash cycle. Surprisingly, significant bleachable stain removal benefits are obtained over the performance of compositions containing coated percarbonates utilising other coating types when employed in the otherwise equivalent washing process

It is an object of this invention to provide a low temperature, thereby energy-saving, process for washing laundry in a domestic washing machine. It is a further object of this invention to provide a low temperature washing process in which the detergent product is delivered to the wash via a dispensing device.

It is still a further object of this invention to provide a washing process utilising a peroxygen bleach containing laundry detergent composition in which a carbonate/sulphate coated percarbonate bleach is used as a replacement for part or all of the perborate bleaching compounds traditionally found in such compositions.

According to the present invention there is provided a process for washing laundry in a domestic washing machine in which a dispensing device containing an effective amount of a granular laundry detergent composition is introduced into th drum of the washing machine before the commencement of the wash, wherein said dispensing device permits progressive relase of said granular laundry detergent composition into the wash liquor during the wash, and wherein said granular laundry detergent composition has a bulk density greater than 650 g/litre and comprises:

(a) from 1 % to 60% by weight of an alkali metal percarbonate bleach coated with a mixed salt comprising an alkali metal carbonate and an alkali metal sulphate salt; and

(b) from 1 % to 40% by weight of a peroxyacid bleach activator, and wherein:

(i) the weight ratio of said coated percarbonate bleach to said peroxyacid bleach activator lies in the range from 1 : 1 to 10: 1 ; and

(ii) the process is conducted at a temperature of no more than 50°C.

Preferably, said process is conducted at a temperature of no more than 45 °C, and most preferably no more than 40 °C.

Preferably, the weight ratio of said coated percarbonate bleach to said peroxyacid bleach activator lies in the range from 2: 1 to 6: 1 , most preferably from 3: 1 to 5: 1. The first essential component of the granular detergent compositions in accord with the invention is from 1 % to 60% , by weight of the composition, preferably from 3 % to 30% by weight, most preferably from 5% to 25 % by weight of an alkali metal percarbonate bleach coated with a mixed salt comprising an alkai metal carbonate and an alkali metal sulphate salt.

The alkali metal percarbonate bleach is usually in the form of the sodium salt. Sodium percarbonate is an addition compound having a formula corresponding to 2Na2Cθ3 3H2O2. To enhance storage stability the percarbonate bleach is coated with a mixed salt of an alkali metal sulphate and carbonate. Such coatings together with coating processes have previously been described in GB-1 ,466,799, granted to Interox on 9th March 1977. The weight ratio of the mixed salt coating material to percarbonate lies in the range from 1 :200 to 1 :4, more preferably from 1 :99 to 1 :9, and most preferably from 1 :49 to 1 : 19. Preferably, the mixed salt is of sodium sulphate and sodium carbonate which has the general formula Na2Sθ4.n.Na2Cθ3 wherein n is from 0.1 to 3, preferably n is from 0.3 to 1.0 and most preferably n is from 0.2 to 0.5.

Commercially available carbonate/sulphate coated percarbonate bleach may include a low level of a heavy metal sequestrant such as EDTA, 1- hydroxyethylidene 1 ,1-diphosphonic acid (HEDP) or an amino- phosphonate, that is incorporated during the manufacturing process.

Preferred heavy metal sequestrants for incorporation as described herein above include the organic phosphonates and amino alkylene poly(alkylene phosphonates) such as the alkali metal ethane 1 -hydro xy diphosphonates, the nitrilo trimethylene phosphonates, the ethylene diamine tetra methylene phosphonates and the diethylene triamine penta methylene phosphonates.

The second essential component of the granular detergent compositions in accord with the invention is from 1 % to 40% by weight of the composition, preferably from 2% to 15% by weight, most preferably from 3% to 10% by weight of a peroxyacid bleach activator. T/US93/06302

Peroxyacid bleach activators (bleach precursors) as additional bleaching components in accord with the invention can be selected from a wide range of classes and are preferably those containing one or more N- or 0- acyl groups.

Suitable classes incldue anhydrides, esters, amides and acylated derivatives of imidazoles and oximes, and examples of useful materials within these classes are disclosed in GB-A- 1586789. The most preferred classes are esters such as are disclosed in GB-A-836 988, 864798, 1 147 871 and 2 143 231 and amides such as are disclosed in GB-A-855 735 and 1 246 338.

Particularly preferred bleach activator compounds as additional bleaching components in accord with the invention are the N-,N,N'N' tetra acetylated compounds of formula

CH₃ C _N CCH-

0 0

where x can be O or an integer between 1 and 6.

Examples include tetra acetyl methylene diamine (TAMD) in which x= 1 tetra acetyl ethylene diamine (TAED) in which x=2 and Tetraacetyl hexylene diamine (TAHD) in which x=6. These and analogous compounds are described in GB-A-907 356. The most preferred peroxyacid bleach activator as an additional bleaching component is TAED. Another preferred class of peroxyacid bleach activator compounds are the amide substituted compounds of the following general formulae:

Rl - -OOH

wherein Rl is an aryl or alkaryl group with from about 1 to about 14 carbon atoms, R2 is an alkylene, arylene, and alkarylene group containing from about 1 to 14 carbon atoms, and R^ is H or an alkyl, aryl, or alkaryl group containing 1 to 10 carbon atoms and L can be essentially any leaving group. Rl preferably contains from about 6 to 12 carbon atoms. R2 preferably contains from about 4 to 8 carbon atoms. Rl may be straight chain or branched alkyl, substituted aryl or alkylaryl containing branching, substitution, or both and may be sourced from either synthetic sources or natural sources including for example, tallow fat. Analogous structural variations are permissible for R^. The substitution can include alkyl, aryl, halogen, nitrogen, sulphur and other typical substituent groups or organic compounds. R^ is preferably H or methyl. R and R^ should not contain more than 18 carbon atoms total. Amide substituted bleach activator compounds of this type are described in EP-A-0170386.

Other peroxyacid bleach activator compounds include sodium nonanoyloxy benzene sulfonate, sodium trimethyl hexanoyloxy benzene sulfonate, sodium acetoxy benzene sulfonate and sodium benzoyloxy benzene sulfonate as disclosed in, for example, EP-A-0341947.

The compositions of the invention in addition comprise, in general terms, those ingredients conventionally found in laundry detergent products.

A wide range of surfactants can be used in the detergent compositions. A typical listing of anionic, nonionic, amphyolytic and zwitterionic classes, and species of these surfactants, is given in U.S. P. 3,929,678 issued to Laughlin and Heuring on December 30, 1975. A list of suitable cationic surfactants is given in U.S. P. 4,259,217 issued to Murphy on March 31, 1981. Mixtures of anionic surfactants are suitable herein, particularly blends of sulphate, sulphonate and/or carboxylate surfactants. Mixtures of sulphonate and sulphate surfactants are normally employed in a sulphonate to sulphate weight ratio of from 5: 1 to 1 :2, preferably from 3: 1 to 2:3, more preferably from 3: 1 to 1 : 1.

Preferred sulphonates include alkyl benzene sulphonates having from 9 to 15, especially 1 1 to 13 carbon atoms in the alkyl radical, and alpha- sulphonated methyl fatty acid esters in which the fatty acid is derived from a C12- 8 fatty source, preferably from a C\β-C\% fatty source. In each instance the cation is an alkali metal, preferably sodium. Preferred sulphate surfactants in such sulphonate sulphate mixtures are alkyl sulphates having from 12 to 22, preferably 16 to 18 carbon atoms in the alkyl radical. Another useful surfactant system comprises a mixture of two alkyl sulphate materials whose respective mean chain lengths differ from each other. One such system comprises a mixture of C14-C15 alkyl sulphate and Ci6-Cj8 alkyl sulphate in a weight ratio of C14-C15 : C\ - Cj8 of from 3: 1 to 1 : 1. The alkyl sulphates may also be combined with alkyl ethoxy sulphates having from 10 to 20, preferably 10 to 16 carbon atoms in the alkyl radical and an average degree of ethoxylation of 1 to 6. The cation in each instance is again an alkali metal, preferably sodium.

Other anionic surfactants suitable for the purposes of the invention are the alkali metal sarcosinates of formula

R-CON (R!)CH2 COOM wherein R is a C9-C17 linear or branches alkyl or alkenyl C group, Rl is a C1-C4 alkyl group and M is an alkali metal ion. Preferred examples are the lauroyl, Cocoyl (C12-C14), myristyl and oleyl methyl sarcosinates in the form of their sodium salts.

One class of nonionic surfactants useful in the present invention comprises condensates of ethylene oxide with a hydrophobic moiety, providing surfactants having an average hydrophilic-lipophilic balance (HLB) in the range from 8 to 17, preferably from 9.5 to 13.5, more preferably from 10 to 12.5 in which the hydrophobic (lipophilic) moiety may be aliphatic or aromatic in nature. Especially preferred nonionic surfactants of this type are the C9-C15 primary alcohol ethoxylates containing 3-8 moles of ethylene oxide per mole of alcohol, particularly the C14-C15 primary alcohols containing 6-8 moles of ethylene oxide per mole of alcohol and the \2- \4 primary alcohols containing 3-5 moles of ethylene oxide per mole of alcohol.

A further preferred class of nonionc surfactants comprises polyhydroxy fatty acid amides of general formula:

O Ri

11 1 ^L

R_{2 C N Z}

where R\ is H, a C1-C4 hydrocarbyl, 2 hydroxy ethyl, 2-hydroxypropyl or mixtures thereof, R2 is a C5-C31 hydrocarbyl and Z is a polyhydroxyhydrocarbyl having a linear hydrocarbyl chain with at least three hydroxy groups directly connected to the chain, or an alkoxylated derivative thereof. In preferred members of this class the polyhydroxy hydrocarbyl moiety is derived from glucose of maltose or mixtures thereof and the R2 group is a C11-C19 alkyl or alkenyl moiety as the Rj group. Compositions incorporating such highly preferred polyhydroxy fatty acid amides are disclosed in the copending British Application No. 9113139 filed June 18 1991.

Another class of nonionic surfactants comprises alkyl polyglucoside compounds of general formula

RO (C_nH_2nO)tZ_x

wherein Z is a moiety derived from glucose; R is a saturated hydrophobic alkyl group that contains from 12 to 18 carbon atoms; t is from 0 to 10 and n is 2 or 3; x is from 1.3 to 4, the compounds including less than 10% unreacted fatty alcohol and less than 50% short chain alkyl polyglucosides. Compounds of this type and their use in detergent compositions are disclosed in EP-B 0070074, 0070077, 0075996 and 00941 18. A further class of surfactants are the semi-polar surfactants such as amine oxides. Suitable amine oxides are selected from mono C -C20, preferably Cιo^_Cl4 -alkyl or alkenyl amine oxides and propylene-1 ,3- diamine dioxides wherein the remaining N positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Cationic surfactants can also be used in the detergent compositions herein and suitable quaternary ammonium surfactants are selected from mono C -C16, preferably C10-C14 N-alkyl or alkenyl ammonium surfactants wherein remaining N positions are substituted by methyl, hydroxyethyl ro hydroxypropyl groups.

The detergent compositions comprise from 3 % to 30% by weight of the composition of surfactant but more usually comprise from 5% to 20% by weight, more preferably from 5% to 15% by weight.

Combinations of surfactant types are preferred, more especially anionic- nonionic and also anionic-nonionic-cationic blends. Particularly preferred combinations are described in GB-A-2040987, GB 9113139 and EP-A-0087914. Although the surfactants can be incorporated into the compositions as mixtures, it is preferable to control the point of addition of each surfactant in order to optimise the physical characteristics of the composition and avoid processing problems. Preferred modes and orders of surfactant addition are described hereinafter.

The granular detergent compositions in accord with the invention also preferably comprise a detergent builder system comprising one or more detergent builders, most preferably non-phosphate detergent builders. These can include, but are not restricted to alkali metal carbonates, bicarbonates, silicates, aluminosilicates, monomeric and oligomeric polycarboxylates, homo or copolymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxylic radicals separated from each other by not more than two carbon atoms, and mixtures of any of the foregoing. The builder system is present in an amount of from 5% to 80% by weight of the composition, more preferably from 30% to 60% by weight. Suitable silicates are those having an Siθ2 : Na2θ ratio in the range from 1.6 to 3.4, the so-called amorphous silicates of Siθ2 : Na2θ ratios from

2.0 to 2.8 being preferred. These materials can be added at various points of the manufacturing process, such as in a slurry of components that are spray dried or in the form of an aqueous solution serving as agglomerating agent for other solid components, or, where the silicates are themselves in paniculate form, as solids to the other particulate components of the composition. However, for compositions in which the percentage of spray dried components is low ie 30% , it is preferred to include the amorphous silicate in the spray-dried components.

Within the silicate class, highly preferred materials are crystalline layered sodium silicates of general formula

NaMSi_xθ2χ+ l -yH2θ

wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20. Crystalline layered sodium silicates of this type are disclosed in EP-A-0164514 and methods for their preparation are disclosed in DE-A-3417649 and DE-A-3742043. For the purposes of the present invention, x in the general formula above has a value of 2, 3 or 4 and is preferably 2. More preferably M is sodium and y is O and preferred examples of this formula comprise the <* , , Y and <5^* forms of Na2S-2θ5. These materials are available from Hoechst AG FRG as respectively NaSKS-5, NaSKS-7, NaSKS-11 and NaSKS-6. The most preferred material is -Na2Si2θ5, NaSKS-6. Crystalline layered silicates are incorporated either as dry mixed solids, or as solid components of aggomerates with other components.

Whist a range of aluminosilicate ion exchange materials can be used, preferred sodium aluminosilicate zolites have the unit cell formula Na_z [(AL0₂)z (Siθ2)_y] xH₂0

wherein z and y are at least 6; the molar ratio of z to y is from 1.0 to 0.5 and x is at least 5, preferably from 7.5 to 276, more preferably from 10 to 264. The aluminosilicate materials are in hydrated form and are preferably crystalline, containing from 10% to 28% , more preferably from 18% to 22% water in bound form.

The above aluminosilicate ion exchange materials are further characterised by a particle size diameter of from 0.1 to 10 micrometers, preferably from 0.2 to 4 micometers. The term "particle size diameter" herein represents the average particle size diameter of a given ion exchange material as determined by conventional analytical techniques such as, for example, microscopic determination utilizing a scanning electron microscope or by means of a laser granulometer. The aluminosilicate ion exchange materials are further characterised by their calcium ion exchange capacity, which is at least 200 mg equivalent of CaCθ3 water hardness/g of aluminosilicate, calculated on an anhydrous basis, and which generally is in the range of from 300 mg eq./g to 352 mg eq./g. The aluminosilicate ion exchange materials herein are still further characterised by their calcium ion exchange rate which is at least 130 mg equivalent of CaC03/litre/minute/(g/litre) [2 grains

Ca+ ⁺/gallon/minute/(gram/gallon)] of aluminosilicate (anhydrous basis), and which generally lies within the range of from 130 mg equivalent of CaC03/litre/minute/(gram/litre) [2 grains/gallon/minute/(gram/gallon)] to

390 mg equivalent of CaC03/litre/minute/(gram/litre) [6 grains/gallon/minute/(gram/gallon)], based on calcium ion hardness. Optimum aluminosilicates for builder purposes exhibit a calcium ion exchange rate of at least 260 mg equivalent of CaCθ3/litre/minute/(gram/litre) [4 grains/gallon/minute/(gram/gallon)] . Aluminosilicate ion exchange materials useful in the practice of this invention are commercially available and can be naturally occurring materials, but are preferably synthetically derived. A method for producing aluminosilicate ion exchange materials is discussed in US Patent No. 3,985,669. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations Zeolite A, Zeolite B, Zeolite P, Zeolite MAP, Zeolite X, Zeolite HS and mixtures thereof. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material is Zeolite A and has the formula

Nai2[(AL02)i2 (Si0₂)i2]- xH2θ

wherein x is from 20 to 30, especially 27. Zeolite X of formula Na86 [(ALθ2)86(^SiO2)l06]- ^{276 H}2° ^is also suitable, as well as Zeolite HS of formula Na₆ [(AL0₂)6(Si0₂)6J 7.5 H₂0).

Suitable water-soluble monomeric and oligomeric carboxylate builders can be selected from a wide range of compounds but such compounds preferably have a first carboxyl logarithmic acidity constant (pKj) of less than 9, preferably of between 2 and 8.5, more preferably between 4 and

7.5.

The logarithmic acidity constant is defined by reference to the equilibrium

H + + HA

where A" is the singly ionized anion of the carboxylate builder salt. The equilibrium constant is therefore for dilute solutions given by the expression

Ki = THAI

[H+][A-] and pKi = logioKj .

For the puφoses of this specification, acidity constants are defined as 25 °C and at zero ionic strength. Literature values are taken where possible (see Stability Constants of Metal-Ion Complexes, Special Publication No. 25, the Chemical Society, London): where doubt arises they are determined by potentiometric titration using a glass electrode.

The carboxylate or polycarboxylate builders can be monomeric or oligomeric in type although monomeric carboxylates are generally preferred for reasons of cost and performance.

Monomeric and oligomeric builders can be selected from acyclic, alicyclic, heterocyclic and aromatic carboxylates having the general formulae 14

n

or

wherein R\ represents H, C1-.30 alkyl or alkenyl optionally substituted by hydroxy, carboxy, sulfo or phosphono groups or attached to a polyethyleneoxy moiety containing up to 20 ethyleneoxy groups; R2 represents H, C1.4 alkyl, alkenyl or hydroxy alkyl, or alkaryl, sulfo, or phosphono groups; X represents a single bond; O; S; SO; or NRj _; Y represents H; carboxy; hydroxy; carboxymethyloxy; or Ci_3o alkyl or alkenyl optionally substituted by hydroxy or carboxy groups; Z represents H; or carboxy; m is an integer from 1 to 10; n is an integer from 3 to 6; p, q are integers from 0 to 6, p + q being from 1 to 6; and wherein, X, Y, and Z each have the same or different representations when repeated in a given molecular formula, and wherein at least one Y or Z in a molecule contain a carboxy 1 group. Suitable carboxylates containing one cargoxy group include lactic acid, glycollic acid and ether derivatives thereof as disclosed in Belgian Patent Nos. 831 ,368, 821 ,369 and 821 ,370. Polycarboxylates containing two carboxy groups include the water-soluble salts of succinic acid, malonic acid, (ethylenedioxy) diacetic acid, maleic acid, diglycollic acid, tartaric acid, tartronic acid and fumaric acid, as well as the ether carboxylates described in German Offenlegenschrift 2,446,686, and 2,446,687 and US Patent No. 3,935,257 and the sulfinyl carboxylates described in Belgian Patent No. 840,623. Polycarboxylates containing three carboxy groups include, in particular, water-soluble citrates, aconitrates and citraconates as well as succinate derivatives such as the carboxymethyloxysuccinates described in British Patent No. 1 ,379,241 , lactoxysuccinates described in British Patent No. 1 ,389,732, and aminosuccinates described in Netherlands Application 7205873, and the oxypolycarboxylate materials such as 2-oxa-l , l ,3-propane tricarboxylates described in British Patent No. 1 ,387,447.

Polycarboxylates containing four carboxy groups include oxydisuccinates disclosed in British Patent No. 1 ,261 ,829,1 , and the 1 ,2,2-ethane tetracarboxylates, 1 , 1 ,3,3-propane tetracarboxylates and 1 , 1 ,2,3-propane tetracarboxylates. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives disclosed in British Patent Nos. 1 ,398,421 and 1 ,398,422 and in US Patent No. 3,936,448, and the sulfonated pyrolysed citrates described in British Patent No. 1 ,082,179, while polycarboxylates containing phosphone substituents are disclosed in British Patent No. 1 ,439,000.

Alicyclic and heterocyclic polycarboxylates include cyclopentane-cis, cis,cis-tetracarboxylates, cyclopentadienide pentacarboxylates, 2,3,4,5- tetrahydrofuran - cis, cis, cis-tetracarboxylates, 2,5-tetrahydrofuran -cis - dicarboxylates, 2,2,5,5-tetrahydrofuran - tetracarboxylates, 1 ,2,3,4,5,6- hexane -hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include mellitic acid, pyromellitic acid and the phthalic acid derivatives disclosed in British Patent No. 1 ,425,343.

Of the above, the preferred polycarboxylates are hydroxy carboxylates containing up to three carboxy groups per molecule, more particularly citrates.

The parent acids of the monomeric or oligomeric polycarboxylate chelating agents or mixtures thereof with their salts, eg citric acid or citrate/citric acid mixtures are also contemplated as components of builder systems useful in the present inention.

Other suitable water soluble organic salts are the homo- or co-polymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxyl radicals separated from each other by not more than two carbon atoms. Polymers of the latter type are disclosed in GB-A-1 ,596,756. Examples of such salts are polyacrylates of MWt 2000-5000 and their copolymers with maleic anhydride, such copolymers having a molecular weight of from 20,000 to 70,000, especially about 40,000. These materials are normally used at levels of from 0-.5% to 10% by weight, more preferably from 0.75% to 8% , most preferably from 1 % to 6% by weight of the composition.

For the purposes of compositions in accordance with the invention, the non-phosphate builder ingredient will comprise from 5% to 80% by weight of the composition, more preferably from 30% to 60% by weight. Within the preferred compositions, a sodium aluminosilicate such as Zeolite A will comprise from 20% to 60% by weight of the total amount of builder, a monomeric or oligomeric carboxylate will comprise from 10% to 30% by weight of the total amount of builder and a crystalline layered silicate will comprise from 10% to 65% by weight of the total amount of builder. In such compositions, the builder ingredient preferably also incorporates a combination of auxiliary inorganic and organic builders such as sodium carbonate and maleic anhydride/acrylic acid copolymers in amounts of up to 35% by weight of the total builder.

The compositions of the invention may also contain organic perocyacids of which a paerticularly preferred class are the amide substituted peroxyacids of general formulae :

R¹ - C - N-R2 - C - L or Rl - N - C-R² - C - L II I , II l I' n

0 R5 O R5 O O wherein Rl is an aryl or alkaryl group with from about 1 to about 14 carbon atoms, R² is an alkylene, arylene, and alkarylene group containing from about 1 to 14 carbon atoms, and R^ is H or an alkyl, aryl, or alkaryl group containing 1 to 10 carbon atoms and L can be essentially any leaving group. R preferably contains from about 6 to 12 carbon atoms. R preferably contains from about 4 to 8 carbon atoms. Rl may be straight chain or branched alkyl, substituted aryl or alkylaryl containing branching, substitution, or both and may be sourced from either synthetic sources or natural sources including for example, tallow fat. Analogous structural variations are permissible for R². The substitution can include alkyl, aryl, halogen, nitrogen, sulphur and other typical substituent groups or organic compounds. R^ is preferably H or methyl. Rl and R^ should not contain more than 18 carbon atoms total. Organic peroxyacid compounds of this type are described in EP-A-0170386.

Other organic peroxyacids include diperoxy dodecanedioc acid, diperoxy tetra decanedoic acid, diperoxyhexadecanedoic acid, mono- and diperazelaic acid, mono-and diperbrassylic acid, monoperoxy phthalic acid, perbenzoic acid, and their salts as disclosed in, for example, EP-A- 0341 947.

Preferred heavy metal sequestrants for inclusion in the detergent compositions of the invention include the organic phosphonates, including amino alkylene poly (alkylene phosphonates), alkali metal ethane 1- hydroxy diphosphonates, nitrilo trimethylene phosphonates, ethylene diamine tetra methylene phosphonates and diethylene triamine penta methylene phsophonates. Such phosphonate compounds may be present either in their acid form or as a complex of either an alkali or alkaline metal ion, the molar ratio of said metal ion to said phosphonate compound being at least 1 : 1. Such complexes are described in US-A-4,259,200. Preferably, the organic phosphonate compounds are in the form of their magnesium salt.

Organic phosphonate compounds, and mixtures thereof, may be present in the detergent compositions of the invention at levels of from 0.05% to 10% by weight of the composition, preferably 0.1 % to 2% by weight, most preferably 0.2% to 0.6% by weight.

Compositions in accordance with the invention can also contain other optional detergent ingredients. Anti-redeposition and soil-suspension agents, optical brighteners, soil release agents, dyes and pigments are examples of such optional ingredients and can be added in varying amounts as desired.

Anti-redeposition and soil-suspension agents suitable herein include cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxyethylcellulose, and homo- or co-polymeric polycarboxylic acids or their salts. Polymers of this type include copolymers of maleic anhydride with ethylene, methyl vinyl ether or methacrylic acid, the maleic anhydride constituting at least 20 mole percent of the copolymer. These materials are normally used at levels of from 0.5 % to 10% by weight, more prefeably from 0.75% to 8% , most preferably from 1 % to 6% by weight of the composition.

Other useful polymeric materials are the polyethylene glycols, particularly those of molecular weight 1000 - 10000, more particularly 2000 to 8000 and most preferably about 4000. These are used at levels of from 0.20% to 5% , more preferably from 0.25% to 2.5 % by weight. These polymers and the previously mentioned homo-or co-polymeric polycarboxylate salts are valuable for improving whiteness maintenance, fabric ash deposition, and cleaning performance of clay, proteinaceous and oxidizable soils in the presence of transition metal impurities.

Preferred optical brighteners are anionic in characters, examples of which are disodium 4,4l-bis-(2-diethanolomino-4-anilino -s- triazin-6- ylamino)stilbene-2:2l disulphonate, disodium 4, 4l-bis-(2-morpholino-4- anilino-s-triazin-6-ylamino stilbene-2:2l - disulphonate, disodium 4, 4 - bis-(2,4-dianilino-s-triazin-6-ylamino)stilbene-2:2l - disulphonate, monosodium 4I , 4H -bis-(2,4-dianilino-s-triazin-6 ylamino) stilbene-2- sulphonate, disodium 4, 4l-bis-(2-anilino-4-(N-methyl-N-2- hydroxyethylamino)-s-triazin-6-ylamino)stilbene-2,2l - disulphonate, disodium 4,4l-bis-(4-phenyl-2, 1 ,3-triazol-2-yl)-stilbene-2,2l disulphonate, disodium 4,4lbis(2-anilino-4-(l-methyl-2- hydroxyethy lamino)-s-triazin-6-y lamino)stilbene-2 ,21 disulphonate and sodium 2(stilbyl-4l l-(naphtho-l l , 2l ;4,5)-l,2,3 - triazole-2H -sulphonate.

Soil-release agents useful in composition of the present invention are conventionally copolymers or terpolymers of terephthalic acid with ethylene glycol and/or propylene glycol units in various arrangements. Examples of such polymers are disclosed in the commonly assigned US Patent Nos. 4116885 and 471 1730 and European Published Patent Application No. 0272033. A particular preferred polymer in accordance with EP-A-0272033 has the formula

(CH3(PEG)43)o.₇5(POH)₀.25fT-PO)_{2- 8}(T-PEG)₀.4]T(PO-H)₀.25((PEG)43CH₃)₀.₇₅ where PEG is -(OC₂H₄)0-,PO is (OC₃H₆0) and T is (pCOC₆H₄CO).

Certain polymeric materials such as polyvinyl pyrrolidones typically of MWt 5000-20000, preferably 10000-15000, also form useful agents in preventing the transfer of labile dyestuffs between fabrics during the washing process.

Another optional ingredient is a suds suppressor, exemplified by silicones, and silica-silicone mixtures. Silicones can be generally represented by alkylated polysiloxane materials while silica is normally used in finely divided forms, exemplified by silica aerogels and xerogels and hydrophobic silicas of various types. These materials can be incorporated as particulates in which the suds suppressor is advantageously releasably incorporated in a water-soluble or water- dispersible, substantially non-surface-active detergent-impermeable carrier. Alternatively the suds suppressor can be dissolved or dispersed in a liquid carrier and applied by spraying on to one or more of the other components.

As mentioned above, useful silicone suds controlling agents can comprise a mixture of an alkylated siloxane, of the type referred to hereinbefore, and solid silica. Such mixtures are prepared by affixing the silicone to the surface of the solid silica. A preferred silicone suds controlling agent is represented by a hydrophobic silanated (most preferably trimethyl- silanated) silica having a particle size in the range from 10 nanometers to 20 nanometers and a specific surface area above 50 πfi/g, intimately admixed with dimethyl silicone fluid having a molecular weight in the range from about 500 to about 200,000 at a weight ratio of silicone to silanated silica of from about 1 : 1 to about 1 :2.

A preferred silicone suds controlling agent is disclosed in Bartollota et al US Patent 3,933,672. Other prticularly useful suds suppressors are the self-emulsifying silicone suds suppressors, described in German Patent Application DTOS 2,646, 126 published April 28, 1977. An example of such a compound is DC-544, commercially available from Dow Corning, which is a siloxane/glycol copolymer.

The suds suppressor described above are normally employed at levels of from 0.001 % to 0.5 % by weight of the composition, preferably from 0.01 % to 0.1 % by weight.

The preferred methods of incorporation comprise either application of the suds suppressors in liquid form by spray-on to one or more of the major components of the composition or alternatively the formation of the suds suppressors into separate particulates that can then be mixed with the other solid components of the composition. The incorporation of the suds modifiers as separate particulates also permits the inclusion therein of other suds controlling materials such as C20^_C24 fatty acids, microcrystalline waxes and high MWt copolymers of ethylene oxide and propylene oxide which would otherwise adversely affect the dispersibility of the matrix. Techniques for forming such suds modifying particulates are disclosed in the previously mentioned Bartollotta et al US Patent No. 3,933,672. An other optional ingredient useful in the present invention is one or more enzymes.

Preferred enzymatic materials include the commercially available amylases, neutral and alkaline proteases, upases, esterases and cellulases conventionally incorporated into detergent compositions. Suitable enzymes are discussed in US Patents 3,519,570 and 3,533,139.

Preferred commercially available protease enzymes include those sold under the tradnames Alcalase and Savinase by Novo Industries A/S (Denmark) and Maxatase by International Bio-Synthetics, Inc. (The Netherlands).

Preferred amylases include, for example, -amylases obtained from a special strain of B licheniforms, described in more detail in GB-1 ,296,839 (Novo). Preferred commercially available amylases include for example, Rapidase, sold by International Bio-Synthetics Inc. and Termamyl, sold by Novo Industries A/S.

An especially preferred lipase enzyme is manufactured and sold by Novo Industries A/S (Denmark) under the trade name Lipolase (Biotechnology Newswatch, 7 March 1988, page 6) and mentioned along with other suitable upases in EP-A-0258068 (Novo).

Levels of smectite clay are normally in the range from 5 % to 15 % , more preferably from 8% to 12% by weight, with the material being added as a dry mixed component to the remainder of the formulation. Organic fabric softening agents such as the water-insoluble tertiary amines or dilong chain amide materials are incorporated at levels of from 0.5% to 5% by weight, normally from 1 % to 3 % by weight, whilst the high molecular weight polyethylene oxide materials and the water soluble cationic materials are added at levels of from 0.1 % to 2% , normally from 0.15% to 1.5 % by weight. Where a portion of the composition is spray dried, these materials can be added to the aqueous slurry fed to the spray drying tower, although in some instances it may be more convenient to add them as a dry mixed particulate, or spray them as a molten liquid on to other solid components of the composition.

A feature of the composition of the present invention is that they are of relatively high density in comparison with conventional laundry detergent compositions. Such high density compositions have become known as concentrated products and are characterised by a bulk density of at least 650 g/litre, more usually at least 700 g/litre and more preferably in excess of 800 g/litre. Bulk density is measured by means of a simple funnel and cup device consisting of a conical funnel moulded rigidly on a base and provided with a flap valve at its lower extremity to allow the contents of the funnel to be emptied into an axially aligned cylindrical cup disposed below the funnel. The funnel is 130 mm high and has internal diameters of 130 mm and 40 mm at its respective upper and lower extremities. It is mounted so that the lower extremity is 140 mm above the upper surface of the base. The cup has an overall height of 90 mm, an internal height of 87 mm and an internal diameter of 84 mm. Its nominal volume is 500 ml.

To carry out a measurement, the funnel is filled with powder by hand pouring, the flap valve is opened and powder allowed to overfill the cup. The filled cup is removed from the frame and excess powder removed from the cup by passing a straight edged implement eg; a knife, across its upper edge. The filled cup is then weighed and the value obtained for the weight of powder doubled to provide a bulk density in g/litre. Replicate measurements are made as required.

Another feature of compositions of the present invention is that they incorporate at least one multi-ingredient component ie they do not comprise compositions formed merely by dry-mixing individual ingredients. Compositions in which each individual ingredient is dry- mixed are generally dusty, slow to dissolve and also tend to cake and develop poor particle flow characteristics in storage.

Subject to the above bulk density and component content limitations, the compositions of the invention can be made via a variety of methods including dry mixing, spray drying, agglomeration and granulation and preferred methods involve combinations of these techniques. A preferred method of making the composition involves a combination of spray drying, agglomeration in a high speed mixer and dry mixing.

Preferred detergent compositions in accordance with the invention comprise at least two particulate multi-ingredient components. The first component comprises at least 15% , conventionally from 25% to 50% , but more preferably no more than 35 % by weight of the composition and the second component from 1 % to 50% , more preferably 10% to 40% by weight of the composition.

In a preferred embodiment of the invention, one multi-ingredient component comprises an agglomerate of non-spray-dried ingredients together with a second multi-ingredient component comprising a spray- dried powder.

The first component comprises a particulate incorporating an anionic surfactant in an amount of from 0.75% to 40% by weight of the powder and one or more inorganic and/or organic salts in an amount of from 99.25% to 60% by weight of the powder. The particulate can have any suitable form such as granules, flakes, prills, marumes or noodles but is preferably granular. The granules themselves may be agglomerates formed by pan or drum agglomeration or by in-line mixers but are customarily spray dried particles produced by atomising an aqueous slurry of the ingredients in a hot air spream which removes most of the water. The spray dried granules are then subjected to densification steps, eg by high speed cutter mixers and. /or compacting mills, to increase density before being reagglomerated. For illustrative purposes, the first component is described hereinafter as a spray dried powder.

Suitable anionic surfactants for the purposes of the first component have been found to be slowly dissolving linear alkyl sulfate salts in which the alkyl group has an average of from 16 to 22 carbon atoms, and linear alkyl carboxylate salts in which the alkyl group has an average of from 16 to 24 carbon atoms. The alkyl groups for both types of surfactant are preferably derived from natural fats such as tallow. Shorter chain alkyl sulfates or carboxylates, in which the alkyl group is derived from sources comprising a mixture of alkyl moieties more than 40% of which contain 14 or less carbon atoms, are less suitable as they cause the first component to form a gel like mass during dissolution.

The level of anionic surfactant in the spray dried powder forming the first component is from 0.75% to 40% by weight, more usually 2.5% to 25% , preferably from 3 % to 20% and most preferably from 5% to 15% by weight. Water-soluble surfactants such as linear alkyl benzene sulphonates or C14-C15 alkyl sulphates can be included or alternatively may be applied subsequently to the spray dried powder by spray on.

The other major ingredient of the spray dried powder is one or more inorganic or organic salts that provide the crystalline structure for the granules. The inorganic and/or organic salts may be water-soluble or water-insoluble, the latter type being comprised by the, or the major part of the, water-insoluble builders where these form part of the builder ingredient. Suitable water soluble inorganic salts include the alkali metal carbonates and bicarbonates. Alkali metal silicates other than crystalline layered silicates can also be present in the spray dried granule provided that aluminosilicate does not form part of the spray dried component.

Where an aluminosilicate zeolite forms the, or part of the, builder ingredient, it is preferred that it is not added directly by dry mixing to the other components, but is incorporated into the multi-ingredient component(s). Where incorporation of the zeolite takes place in the spray-dried granule, any silicate present should not form part of the spray-dried granule. In these circumstances incorporation of the silicate can be achieved in several ways, eg by producing a separate silicate- containing spray-dried particulate, by incorporating the silicate into an agglomerate of other ingredients, or more preferably by adding the silicate as a dry mixed solid ingredient.

The first component can also include up to 15 % by weight of miscellaneous ingredients such as brighteners, anti-re-deposition agents, photoactivated bleaches and heavy metal sequestering agents. Where the first component is a spray dried powder it will normally be dried to a moisture content of from 7% to 11 % by weight, more preferably from 8 % to 10% by weight of the spray dried powder. Moisture contents of powders produced by other processes such as agglomeration may be lower and can be in the range 1-10% by weight.

The particle size of the first component is conventional and preferably not more than 5 % by weight should be above 1.4 mm, while not more than 10% by weight should be less than 0.15 mm in maximum dimension. Preferably at least 60% , and most preferably at least 80% , by weight of the powder lies between 0.9 mm and 0.25 mm in size. For spray dried powders, the bulk density of the particles from the spray drying tower is conventionally in the range from 540 to 600 g/litre and this is then enhanced by further processing steps such as size reduction in a high speed cutter/mixer followed by compaction. Alternatively, processes other than spray drying may be used to form a high density particulate directly.

A second component of a preferred composition in accordance with the invention is another multi-ingredient particulate containing a water soluble surfactant.

This water-soluble surfactant may be anionic, nonionic, cationic or semipolar in type or a mixture of any of these. Suitable surfactants are listed hereinbefore but preferred surfactants are 4-C15 alkyl sulphates linear C11-C 15 alkyl benzene sulphonates and fatty C14-C18 methyl ester sulphonates. The second component may have any suitable physical form ie; it may take the form of flakes, prills, marumes, noodles, ribbons or granules which may be spray-dried or non spray-dried agglomerates. Although the second component could in theory comprise the water soluble surfactant on its own, in practice at least one organic or inorganic salt is included to facilitate processing. This provides a degree of crystallinity, and hence acceptable flow characteristics, to the particulate and may be any one or more of the organic or inorganic salts present in the first component. The particle size range of the second component is not critical but should be such as to obviate segregation from the particles of the first component when blended therewith. Thus not more than 5% by weight should be above 1.4 mm while not more than 10% should be less than 0.15 mm in maximum dimension.

The bulk density of the second component will be a function of its mode of preparation. However, the preferred form of the second component is a mechanically mixed agglomerate which may be made by adding the ingredients dry or with an agglomerating agent to a pan agglomerator, Z blade mixer or more preferably an in-line mixer such as those manufactured by Schugi (Holland) BV 29 Chroomstraat 8211 AS, Lelystad, Netherlands and Gebruder Lodige Maschinenban GmbH, D- 4790 Paderborn 1 , Elsenerstrasse 7-9, Postfach 2050 FRG. By this means the second component can be given a bulk density in the range from 650 g/litre to 1190 g/litre more preferably from 750 g/litre to 850 g/litre.

Preferred compositions include a level of alkali metal carbonate in the second component corresponding to an amount of from 3 % to 15% by weight of the composition, more preferably from 5% to 12% by weight. This will preferably provide a level of carbonate in the second component of from 20% to 40% by weight.

A highly preferred ingredient of the second component is also a hydrated water insoluble aluminosilicate ion exchange material of the synthetic zeolite type, described hereinbefore, present at from 10% to 35% by weight of the second component. The amount of water insoluble aluminosilicate material incorporated in this way is from 1 % to 10% by weight of the composition, more preferably from 2% to 8% by weight. In one process for preparing the second component, the surfactant salt is formed in situ in an inline mixer. The liquid acid form of the surfactant is added to a mixture of particulate anhydrous sodium carbonate and hydrated sodium aluminosilicate in a continuous high speed blender such as a lodige C6 mixer and neutralised to form the surfactant salt whilst maintaining the particulate nature of the mixture. The resultant agglomerated mixture forms the second component which is then added to other components of the product. In a variant of this process, the surfactant salt is pre-neutralised and added as a viscous paste to the mixture of the other ingredients. In this variant, the mixer serves merely to agglomerate the ingredients to form the second component.

In a particularly preferred process for making compositions in accordance with the invention, part of the spray dried product comprising the first granular component is diverted and subjected to a low level of nonionic surfactant spray-on before being reblended with the remainder. The second granular component is made using the preferred process described above. The first and second components together with other dry mix ingredients such as any carboxylate chelating agent, the sodium percarbonate bleach, bleach activator, soil-release polymer, silicate of conventional or crystalline layered type and enzyme are then fed to a conveyor belt, from which they are transferred to a horizontally rotating drum in which perfume and silicone suds suppressor are sprayed on to the product. In highly preferred compositions, a further drum mixing step is employed in which a low (approx. 2% by weight) level of finely divided crystalline material is introduced to increase density and improve granular flow characteristics. This material should not however be an aluminosilicate zeolite builder as it has been found that zeolite builders present in discrete particulate form in the product have an adverse effect on percarbonate stability.

In the washing process of the invention a dispensing device containing an effective amount of granular detergent product is introduced into the drum of a washing machine before the commencement of the wash cycle. What constitutes an effective amount of granular detergent product for use in the process described here in above will depend on the volume and weight of the laundry load to be washed. Use of between 70-150 g of product would be typical for a normal wash load of between 2-6 kg of averagely soiled laundry.

The dispensing device is a container for the detergent product which is used to deliver the product directly into the drum of the washing machine. Its volume capacity should be such as to be able to contain sufficient detergent product as would normally be used in a washing process as hereinbefore described.

Once the washing machine has been loaded with laundry the dispensing device containing the detergent product is placed inside the drum. At the commencement of the wash cycle of the washing machine water is introduced into the drum and the drum periodically rotates. The design of the dispensing device should be such that it permits containment of the dry detergent product but then allows release of this product during the wash cycle in response to its agitation as the drum rotates and also as a result of its immersion in the wash water.

To allow for release of the detergent product during the wash the device may possess a number of openings through which the product may pass. Alternatively, the device may be made of a material which is permeable to liquid but impermeable to the solid product, which will allow release of dissolved product. Preferably, the detergent product will be rapidly released at the start of the wash cycle thereby providing transient localised high concentrations of product in the drum of the automatic washing machine at this stage of the wash cycle.

Preferred dispensing devices are reusable and are designed in such a way that container integrity is maintained in both the dry state and during the wash cycle. Especially preferred dispensing devices for use in accord with the invention have been described in the following patents; GB-B-2, 157, 717, GB-B-2, 157, 718, EP-A-0201376, EP-A-0288345 and EP-A- 0288346. An article by J. Bland published in Manufacturing Chemist, November 1989, pages 41-46 also describes especially preferred dispensing devices for use with granular laundry products which are of a type commonly know as the "granulette" . Another preferred means of carrying out the process of the invention is to introduce the composition into the liquid surrounding the fabrics that are in the drum via a reusable dispensing device having walls that are permeable to liquid but impermeable to the solid composition.

Especially preferred devices of this kind are disclosed in European Patent Application Publication Nos. 0343069 & 0343070. The latter Application discloses a device comprising a flexible sheath in the form of a bag extending from a support ring defining an orifice, the orifice being adapted to admit to the bag sufficient product for one washing cycle in a washing process. A portion of the washing medium flows through the orifice into the bag, dissolves the product, and the solution then passes outwardly through the orifice into the washing medium. The support ring is provided with a masking arrangemnt to prevent egress of wetted, undissolved, product, this arrangement typically comprising radially extending walls extending from a central boss in a spoked wheel configuration, or a similar structure in which the walls have a helical form.

Alternatively, the dispensing device may be a flexible container, such as a bag or pouch. The bag may be of fibrous construction coated with a water impermeable protective material so as to retain the contents, such as is disclosed in European published Patent Application No. 0018678. Alternatively it may be formed of a water-insoluble synthetic polymeric material provided with an edge seal or closure designed to rupture in aqueous media as disclosed in European published Patent Application Nos. 0011500, 0011501 , 0011502, and 0011968. A convenient form of water frangible closure comprises a water soluble adhesive disposed along and sealing one edge of a pouch formed of a water impermeable polymeric film such as polyethylene or polypropylene.

The invention is illustrated in the following non limiting examples in which all percentages are on a weight basis unless otherwise stated. In the detergent compositions, the abbreviated component identifications have the following meanings :

LAS Sodium linear C12 alkyl benzene sulphonate

TAS Sodium tallow alcohol sulfate TAE_n Tallow alcohol ethoxylated with n moles of ethylene oxide per mole of alcohol

25E3 A C 12 15 primary alcohol condensed with an average of 3 moles of ethylene oxide

TAED Tetraacetyl ethylene diamine Silicate Amorphorous Sodium Silicate

(Siθ2:Na2θ ratio normally follows)

Carbonate Anhydrous sodium carbonate CMC Sodium carboxymethyl cellulose Zeolite A Hydrated Sodium Aluminosilicate of formula Nai2(Alθ2Siθ2)12 27H2θ having a primary particle size in the range from 1 to 10 micrometers

Citrate Tri-sodium citrate dihydrate

MA/AA Copolymer of 1 :4 maleic/acrylic acid, average molecular weight about 80,000

Enzyme Mixed proteolytic and amylolytic enzyme sold by Novo Industries AS. DETPMP Diethylene triamine penta (Methylene phosphonic acid), marketed by Monsanto under the Trade name Dequest 2060 Percarbonate Anhydrous sodium percarbonate bleach (Si coated) of empirical formula 2Na2Cθ3.3H2θ2 coated with amorphous sodium silicate with an Siθ2:Na2θ ratio of 2.8, and a weight ratio of percarbonate:silicate of

39:1

Percarbonate Anhydrous sodium percarbonate bleach of (CO3/SO4 coated) empirical formula 2Na2Cθ3-3H2θ2 coated with a mixed salt of formula Na2Sθ4.n.Na2Cθ3 where n is 0.29 and where the weight ratio of percarbonate: mixed salt is 39: 1.

NaSKS6 Crystalline layered sodium silicate of formula <f- Na2Si2θ5

Bicarbonate Anhydrous sodium bicarbonate Citric Citric acid

Example 1

The following particulate detergent compositions with a bulk density of approximately 670g/litre were prepared :

A B C

LAS

TAS

25E3

TAE11

Zeolite A

Citrate

MA/AA

Silicate (2.0 ratio)

Carbonate

TAED

PB1

Percarbonate (Si coated)

Percarbonate (CO3/SO4 coated)

DETPMP

MgS04

Enzyme

CMC

Water and minors up to 100

The performance of the three compostions was compared in full scale washing machine tests using Miele 701 washing machines. For each test the short wash cycle and cold setting were selected. The average wash temperature was measured to be 22 °C. Water of 22 °C Clark Hardness (Ca:Mg = 6: 1) was employed. Stained cotton tea-towels were prepared by applying seperate stripes of each of eight different bleachable stains uniformly to each tea-towel. Each wash load comprised 1.5kg of realistically soiled cotton and polycotton ballast fabrics together with one of the stained tea-towels. The total number of replicates for each product was eight.

In each test lOOg of detergent product was placed in a "granulette" type dispensing device which was placed on top of the ballast fabrics and tea- towel in the drum of the washing machine at the start of the wash.

At the end of the wash the tea-towels were dried and then an assessment was made of the amount of each stain type remaining on the tea-towels by an expert panel using a five point Schette scale.

The results of both sets of comparisons are as set out below, the left hand column shows the advantage for composition A over composition B whilst the right hand column shows the comparison of composition A with composition C.

Stain type A/B A/C

Curry

Blackberry

Coffee

Wine

Tea

French coffee

French wine

French tea

Average +0.6 +0.1

Composition A in accord with the invention is noted to give consistently better removal of bleachable stains as compared to composition B which is a comparative product containing 2.8 ratio silicate coated percarbonate. Composition A is noted to perform, on average, equally well as composition C which contains perborate as the only peroxygen bleach. Example 2

The following particulate detergent composition with a bulk density of approximately 670g/litre was prepared in accordance with the invention

D

The composition D gives good washing performance when used in a low temperature ( <50°C) laundry process.

Claims

WHAT IS CLAIMED IS :

1. A process for washing laundry in a domestic washing machine in which a dispensing device containing an effective amount of a granular laundry detergent composition is introduced into the drum of the washing machine before the commencement of the wash, wherein said dispensing device permits progressive release of said granular laundry detergent composition into the wash liquor during the wash, and wherein said granular laundry detergent composition has a bulk density greater than 650 g/litre and comprises:

(b) from 1 % to 40% by weight of a peroxyacid bleach activator, and wherein:

(ii) the process is conducted at a temperature of no more than 50°C.

2. A process according to Claim 1 wherein said laundry detergent composition comprises:

(a) from 3 % to 30% by weight of surfactant, selected from anionic, cationic, nonionic, amphyolytic and zwitterionic surfactants, and mixtures thereof; and

(b) from 5 % to 80% by weight of non-phosphate builder salt, and mixtures thereof.

3. A process according to either one of Claims 1 or 2 wherein said laundry detergent composition comprises from 0.05 % to 10% by weight of an organic phosphonate compound or alkali metal or alkaline earth metal salt thereof, or mixtures thereof

4. A process according to any one of Claims 1-3 wherein said laundry detergent composition comprises from 5% to 25% by weight of said coated percarbonate bleach, from 3% to 10% by weight of said peroxyacid bleach activator and wherein said weight ratio of said coated percarbonate bleach to said peroxyacid bleach activator lies in the range from 2: 1 to 6: 1.

5. A process according to any one of Claims 1-4 wherein said granular laundry detergent composition has a bulk density greater than 800g/litre.

6. A process according to any one of Claims 1-5 wherein said process is conducted at a temperature of no more that 40°C.

7. A process according to any one of the claims 2-6 wherein said non- phosphate builder salt is a crystalline layered silicate material of formula NaMSi x O2 x + 1.yH2θ wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20.

8. A process according to Claim 7 wherein said crystalline layered silicate material is -Na2Si2θ5 (NaSKSό).