GB2428694A

GB2428694A - Acidic granules comprising transition metal catalyst

Info

Publication number: GB2428694A
Application number: GB0515459A
Authority: GB
Inventors: Georg Borchers; Andrew Paul Chapple; Cornelius Paulus Mari Montanus
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 2005-07-28
Filing date: 2005-07-28
Publication date: 2007-02-07
Also published as: GB0515459D0

Abstract

A granule comprising a transition metal catalyst and an acidic component wherein the granule has a diameter in the range from 180-1000 microns. When the granules are dissolved in 50 ml of demineralised water to give an acidic solution, at least 6 ml of 0.01 M NaOH is required to bring the pH of the solution to pH of 9. The preferred acidic component is an acidic polymer such as a polyacrylic acid or an acidic copolymer of acrylic acid and maleic acid. The granule may be coated with an acidic binder material and/or in the form of a tablet. In another aspect, a process for the preaparation of the granule comprising granulating the a transition metal catalyst with the acidic component. In another aspect, a detergent composition comprising the granule and the balance carriers and adjunct ingredients to 100%.

Description

BLEACHING COMPOSITION OF ENHANCED STABILITY AND A PROCESS

FOR MAKING SUCH A COMPOSITION

FIELD OF INVENTION

This invention relates to the stability of transition metal bleaching catalysts in compositions.

BACKGROUND OF INVENTION

The use of bleaching catalysts for stain removal has been developed over recent years. The recent discovery that some catalysts are capable of bleaching effectively in the absence of an added peroxyl source has recently become the focus of some interest, for example: WO9965905; W00012667; W00012808; W00029537, and, W00060045. Most of these catalysts disclosed in these applications may also be used to bleach with peroxyl species.

The shelf life of a product may be regarded as the period of time over which the product may be stored whilst retaining its required quality. A satisfactory shelf life is in many instances a crucial factor for the success of a commercial product. A product with a short shelf life generally dictates that the product is made in small batches and is rapidly sold to the consumer. It is also a concern to the owners of a brand with a short shelf life that the consumer uses the product within the shelf life otherwise the consumer may be inclined to change to a similar product of another brand. In contrast, a similar product with a long * S S II aSS * S I S **I IS S I * S * * I S a * * a S S * I shelf life may be made in larger batches, held as stock for a longer period of time and the period of time that a consumer stores the product is not of a great concern to the owners of a particular brand.

Our application W002066592 discloses the use of acidic components to stabilise transition metal catalysts.

It is an object of the present invention to provide an air/peroxyl bleaching composition comprising a transition metal catalyst that have improved storage properties.

SUMMARY OF INVENTION

In one aspect the present invention provides a granule having a diameter in the range from 180 microns to 1000 microns, the granule comprising a transition metal catalyst and an acidic component, wherein when 1.00 gm of the granules are dissolved in 50 ml of demineralised water to provide an acidic solution at least 6 ml of a 0.01 M solution of sodium hydroxide is required to bring the pH of the acidic solution to 9. The amount in ml of aqueous 0.01 M NaOH required to bring an aqueous solution of 1.00 gm of granules in 50 ml to a pH of 9 being the buffer capacity of the granule.

In a further aspect the present invention provides a process for the preparation of a granule as defined above, the process comprising the steps of: granulating an bleaching catalyst with a component selected from the group consisting of: binder, cogranulent, and a coating, wherein the component selected is acidic, wherein the amount of acidic * S * I. Ss.

* S * S **S S. * I. S S S S S S S S S S S * S S S component used provides a granule having a buffer capacity of at least 6.

DETAILED DESCRIPTION OF THE INVENTION

THE BLEACH CATALYST

Recently we have found that oily stains are bleached in the presence of selected transition metal catalysts in the absence of an added peroxyl source. The bleaching of an oily stain in the absence of an added peroxyl source has been attributed to oxygen derived from the air. Whilst it is true that bleaching is effected by oxygen sourced from the air the route in which oxygen plays a part is becoming understood. In this regard, the term "air bleaching" is used.

We have concluded from our research that bleaching of a chromophore in an oily stain is effected by products formed by adventitious oxidation of components in the oily stain.

These products, alkyl hydroperoxides, are generated naturally by autoxidation of the oily stain and the alkyl hydroperoxides together with a transition metal catalyst serve to bleach chromophores in the oily stain. Alkyl hydroperoxides (ROOH) are generally less reactive that other peroxy species, for example, peracids (RC(O)OOH), hydrogen peroxide (H2O2) , percarbonates and perborates. In this regard, the phrase "for bleaching a substrate with atmospheric oxygen" is synonymous with "for bleaching a substrate via atmospheric oxygen" because it is the oxygen * * I ** III

I I I I I I I

* I I I II. II S I. I I I * I I I

S S S I I S I I

t4* 5 4*a I S in the air that provides the bleaching species used by catalyst to bleach the substrate stain.

The bleach catalyst per se may be selected from a wide range of transition metal complexes of organic molecules (ligands) . In typical washing compositions the level of the organic substance is such that the in-use level is from 0.05 pM to 50 mN, with preferred in-use levels for domestic laundry operations falling in the range 1 to 100 pM. Higher levels may be desired and applied in industrial textile bleaching processes.

Suitable organic molecules (ligands) for forming complexes and complexes thereof are found, for example in: W00012667; EP 0458398; CE 19755493; EP 999050; W09534628; EP458379; EP 0909809; United States Patent 4,728,455; W09839098; W09839406, WO 9748787, WO 0029537; WO 0052124, and W00060045 the complexes and organic molecule (ligand) precursors of which are herein incorporated by reference. An example of a preferred catalyst is a transition metal complex of MeN4Py ligand (N,N-bis(pyridin2-yl-methyl)-l, l-bis(pyridin-2-yl)- 1-aminoethane) The ligand forms a complex with one or more transition metals, in the latter case for example as a dinuclear complex. Suitable transition metals include for example: manganese in oxidation states II-V, iron Il-V1 copper I-Ill, cobalt I-Ill, titanium II-IV, tungsten IV-VI, vanadium Il-V and molybdenum Il-VI.

* * S 5e *II * S I S S I * I I S It. II S II S * I I I I I S S S I S * I I S.. S **I S S An example of a preferred catalyst is a monomer ligand or transition metal catalyst thereof of a ligand having the formula (I) Ri N., (I) wherein each R is independently selected from: hydrogen, F, Cl, Br, hydroxyl, Ci-C4-alkylO--, -NH-CO-H, -NH-CO-Ci-C4- alkyl, -NH2, -NH-Ci-C4-alkyl, and C1-C4-alkyl; Ri and R2 are independently selected from: Ci-C4-alkyl, C6-C10-aryl, and, a group containing a heteroatom capable of co-ordinating to a transition metal, wherein at least one of Ri and R2 is the group containing the heteroatom; R3 and R4 are independently selected from hydrogen, Ci-C8 alkyl, Ci-C8- alkyl-O-Cl-C8-alkyl, C1-C8-alkyl--O-C6-Ci0-aryl, C6-C10-aryl, Cl-C8- hydroxyalkyl, and -(CH2)C(O)OR5 wherein R5 is independently selected from: hydrogen, C1-C4alkyl, n is from 0 to 4, and mixtures thereof; and, X is selected from C=O, -[C(R6)2]- wherein Y is from 0 to 3 each R6 is independently selected from hydrogen, hydroxyl, Ci-C4-alkoxy and Cl-C4-alkyl.

The transition metal complex preferably is of the general formula (Al) h S ** get * * $ S S I * I I I CII Is S Cs I I * I S I I S I * I - I I I * SI. t a [MaLkXn] Ym in which: N represents a metal selected from Mn(II)-(III)-(IV)- (V), Cu(I)-(II)-(III), Fe (II)-(III)-(IV)-(V), Co(I)-(II)- (III), Ti(II)-(III)-(IV), V(II)-(III)-(IV)-(V), Mo(II)(III)-(IV)-(V)-(VI) and W(IV)-(V)-(VI), preferably from Fe(II)-(III)-(IV)(V); L represents the ligand, preferably N,N-bis(pyridin-2- yl-methyl)-l, 1-bis(pyridin-2-yl)-l-aminoethane, or its protonated or deprotonated analogue; X represents a co-ordinating species selected from any mono, bi or tn charged anions and any neutral molecules able to co- ordinate the metal in a mono, bi or trideritate manner; Y represents any non-coordinated counter ion; a represents an integer from 1 to 10; k represents an integer from 1 to 10; n represents zero or an integer from 1 to 10; m represents zero or an integer from 1 to 20.

THE ACIDIC COMPONENT

The acidic component according to the present invention may be watersoluble acidic polymer. The polymer may be used in the compositions according to the present invention to coat, bind or act as co-granulent to the air bleaching catalyst.

In a preferred embodiment of the present invention, the air bleaching catalyst, with or without co-granulant, is agglomerated, preferably with a water-soluble acidic polymer. The co-granulant is a solid material that is mixed S S 5, 51.

* 4 5 4 4 4 S * I I *4 IS I 4* 4 4 I I I I S S I - . 4 4. I as. I 5 with another granulant. Coating and binders are generally at some stage liquid when granulation takes place.

The amount of the acidic component to provide the buffer capacity adds to the overall cost of the product. The buffer capacity provided by the disclosure of our application W002066592 is approximately 4.7. By increasing the buffer capacity to at least 6, a significant increase in stability is provided which offsets the added cost the expensive acidic component.

In one embodiment of the invention the binder material and the coating material are different water-soluble acidic polymers, but in another, preferred embodiment of the present invention, the binder material and the coating material are the same water-soluble acidic polymer.

In determining the scope of the present invention one skilled in the art will appreciate that a coating agent, a binder and a cogranulent may be regarded as providing overlapping functions. Nevertheless, a single function is all that is required to provide the advantage of the present invention. If the acidic component is applied so that all three roles are fulfilled a greater stability may be conferred.

Suitable water-soluble monomeric or oligomeric carboxylate builders include lactic acid, glycolic 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, * I S 5 5_ I I 4 a I I 1,5 II & 4. 4 I S I & S I I I & # I 414 4 III I rnaleic acid, diglycolic 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 U.S. 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 is 2-oxa-1,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, 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 U.S. Patent No. 3,936,448, and the sulfonated pyrolysed citrates described in British Patent No. 1,439,000.

Another preferred polycarboxylate builder is ethylenediamine-N,N'disuccinic acid (EDDS) or the alkali metal, alkaline earth metal, amnionium, or substituted arrmmonium salts thereof, or mixtures thereof. Preferred EDDS compounds are the free acid form and the sodium or magnesium salt thereof. Examples of such preferred sodium salts of EDDS include NaEDDS, Na2EDDS and Na4EDDS.

.:. .: : Examples of such other magnesium salts of EDDS include MgEDDS and Mg2EDDS. The magnesium salts are the most preferred for inclusion in compositions in accordance with the invention.

The structure of the acid form of EDDS is as follows:

H H

NCCN

/ H2H2 \ / \ _________H2 H20 CH H C

COOH COOH COOH COCH

EDDS can be synthesised, for example, from readily available, inexpensive starting material such as maleic anhydride and ethylene diamine. A more complete disclosure of methods for synthesising EDDS from commercially available starting materials can be found in US Patent 3,158,635, Kezerian and Ramsay, issued November 24, 1964.

The synthesis of EDDS from maleic anhydride and ethylene diamine yields a mixture of three optical isomers, [R,R], [S,S), and (S,R], due to the two asymmetric carbon atoms. The biodegradation of EDDS is optical isomerspecific, with the [S,S] isomer degrading most rapidly and extensively, and for this reason the (S,S) isomer is most preferred for inclusion in the compositions of the invention.

The [S,S] isomer of EDDS can be synthesised by heating L- aspartic acid and l,2-dibromoetharie in the presence of I*. II, I * I S * I. *** I, * * ** III * I * * I * I I.. * ** **I I - 10 - sodiun hydroxide. A more complete disclosure of the reaction of L- aspartic acid with 1,2-dibromoethane to form the (S,S) isomer of EDDS can be found in Neal and Rose, Stereospecific Ligands and Their Complexes of Ehtylenediaminediscuccinic Acid, Inorganic Chemistry, Vol 7 (1968), pp. 2405-2412.

Alicyclic and heterocyclic polycarboxylates may be used, these 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 phthal c acid derivatives disclosed in British Patent No. 1,425,343. Of the above, the preferred polycarboxylates are hydroxycarboxylates 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, e.g. citric acid or citrate/citric acid mixtures are also contemplated as components of builder systems of detergent compositions in accordance with the present invention.

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 * * *** S *. S..

: : : ** *5 6 66* S

- II -

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 to 5000 and their copolyrners with maleic anhydride, such copolymers having a molecular weight of from 20,000 to 70,000, especially about 40,000.

Such builder polymeric materials may be identical to the polymeric materials used as binder materials and coating materials, as described hereinabove. 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.

organic phosphonates and amino alkylene poly (alkylene phosphonates) include alkali metal ethane 1-hydroxy diphosphonates, nitrilo trimethylene phosphonates, ethylene diamine tetra methylene phosphonates and diethylene 1,12 triamine pentamethylenephosphonates, although these materials are less preferred where the minimisation of phosphorus compounds in the compositions is desired.

Suitable polymers for use herein are water-soluble. By water-soluble, it is meant herein that the polymers have a solubility greater than 5 g/l at 20 C.

Suitable polymers for use herein are acidic. By acidic, it is meant herein that a 1% solution of said polymers has a pH of less than 7, preferably less than 5.5.

Suitable polymers for use herein have a molecular weight in the range of from 1000 to 280,000, preferably from 1500 to : :1: : , *.

*: : * . I:. S. (A - 12 - 150,000, preferably, suitable polymers for use herein have a melting point above 30 C.

Suitable polymers which meet the above criteria and are therefore particularly useful in the present invention, include those having the following empirical formula I Ri Yp ( XCR3) R2 (I) CO2M wherein X is 0 or CH2; Y is a comonomer or comonomer mixture; Rl and R2 are bleach-stable polymer-end groups; R3 is H, OH or Ci-4 alkyl; N is H, and mixtures thereof with alkali metal, alkaline earth metal, ammonium or substituted arnmonium; p is from 0 to 2; and n is at least 10, and mixtures thereof. The proportion of N being H in such polymers must be such as to ensure that the polymer is sufficiently acidic to meet the acidity criteria as hereinbefore defined.

Polymers according to formula I are known in the field of laundry detergents, and are typically used as chelating agents, as for instance in GB-A-1,597,756. Preferred polycarboxylate polymers fall into several categories. A first category belongs to the class of copolymeric polycarboxylate polymers which, formally at least, are formed from an unsaturated polycarboxylic acid such as maleic acid, citraconic acid, itaconic acid and mesacoriic acid as first monomer, and an unsaturated monocarboxylic : : : .:.

: .: :: * :: :.

- 13 - acid such as acrylic acid or an alpha -01-04 alkyl acrylic acid as second monomer. Referring to formula I, therefore, preferred polycarboxylate polymers of this type are those in which X is CHO, R3 is H or 01-4 alkyl, especially methyl, p is from about 0.1 to about 1.9, preferably from about 0.2 to about 1.5, n averages from about 10 to about 1500, preferably from about 50 to about 1000, more preferably from to 800, especially from 120 to 400 and Y comprises monomer units of formula II

H H

I I (II) CO2M CO2M Such polymers are available from BASF under the trade name Sokalan CP5 (neutralised form) and Sokajan 0245 (acidic form) A second category belongs to the class of polycarboxylate polymers in which referring to formula I, X is 0H2, R3 is OH, p is from 0 to 0.1, preferably 0 and n averages from about 50 to about 1500, preferably from about 100 to 1000.

Y, if present, can be a polycarboxylic acid such as II above, or an ethylene oxide moiety.

A third category belongs to the class of acetal polycarboxylate polymers in which, referring to formula I, X is (0R4)2, where R4 is 01-04 alkyl, R3 is H, p is from 0 to 0.1, preferably 0 and n averages from 10 to 500. If present, Y again can be a polycarboxylic acid such as II above or an ethyleneoxide moiety.

* * Is. S I S * I SI S * * Ii* ** I * * * * * *5 - 14 - A fourth category belongs to the class of polycarboxylate polymers in which referring to formula I, X is 0H2, R3 is I-i or 01-4 alkyl, p is 0 and n averages from about 10 to 1500, preferably from about 500 to 1000.

A fifth category of polycarboxylate polymers has the formula I in which X is 0H2, R3 is H or 01-4 alkyl, especially methyl, p is from 0.01 to 0.09, preferably from 0.02 to 0.06, n averages from about 10 to about 1500, preferably from about 15 to about 300 and Y is a polycarboxylic acid formed from maleic acid, citraconic acid, mitaconic acid or mesaconic acid, highly preferred being maleic acid-derived comonomers of formula II above.

Suitable polymer end groups in formula I suitably include alkyl groups, oxyalkyl groups and alkyl carboxylic acid groups and salts and esters thereof.

In formula I above, N is H or mixtures thereof with alkali metal, alkaline earth metal, ammonium or substituted amrnonium. The proportion of N which is H is such as to ensure that the polymer meets the pH criteria described herein above.

In the above, n, the degree of polymerization of the polymer can be determined from the weight average polymer molecular weight by dividing the latter by the average monomer molecular weight. Thus, for a maleicacrylic copolymer having a weight average molecular weight of 15,500 and comprising 30 mole % of maleic acid derived units, n is 182 (i.e., 15.00/(116 x 0.3 + 72 x 0.7).

* : : * *.

* * .0e ** I * 4S* * * I * - 15 - In case of doubt, weight-average polymer molecular weights can be determined herein by gel permeation chromotography using Water [mu] Porasil (RTM) GPC 60 A2 and (mu) Bondagel (RTM) E-125, E-500 and E-l000 in series, temperature- controlled columns at 40 C against sodium polystyrene suiphonate polymer standards, available from Polymer Laboratories Ltd., Shropshire, UK, the polymer standards being O.15M sodium dihydrogen phosphate and 0.02M tetramethyl amrnonium hydroxide at pH 7.0 in 80/20 water/acetonitrile.

Mixtures of polycarboxylate polymers are also suitable herein, especially mixtures comprising a high molecular weight component having an n value of at least 100, preferably at least 120, and a low molecular weight component having an n value of less than 100, preferably from 10 to 90, more preferably from 20 to 80. Such mixtures are optimum from the viewpoint of providing excellent bleach stability and anti-incrustation performance in the context of a zerophosphate detergent formula.

In mixtures of this type, the weight ratio of high molecular weight component to low molecular weight component is generally at least hi, preferably from about 1:1 to about 20:1, more preferably from about 1.5:1 to about 10.1, especially from about 2:1 to about 8:1.

Preferred polycarboxylate polymers of the low molecular weight type are polycarboxylate polymers of the fourth category (homopolyacrylate polymers) listed above.

I I

* , I * * *. *.* I. : ** *.* ** I * * * * * I * * I ** * S * * S - 16 - Of all the above, highly preferred polycarboxylate polymers herein are those of the first category in which n averages from 100 to 800, preferably from 120 to 400 and mixtures thereof with polycarboxylate polymers of the fourth category in which n averages from 10 to 90, preferably from 20 to 80.

Other suitable polymers for use herein include polymers derived from amino acids such as polyglutamine acid, as disclosed in co-pending application GB 91-20653.2, and polyaspartic acid, as disclosed in EP 305 282, and EP 351 629.

Alternatively, the binder component may be a component together with an acid e.g., polyvinyl alcohol and a liquid acid.

PARTICLE WITH ENHANCED STABILITY

It is essential that the bleaching catalyst is close to or in contact with an acidic material. The bleaching catalyst is in the form of a particle that is amorphous or crystalline. The size of particle may be in the range of 0.01 to 3000 pm. It is most preferred that the bleaching catalyst has a particle size in the range of 5 to 1000 pm, most preferably 50 pm to 100 pm. The size as given is the maximum length in any one direction of the particle.

The bleaching catalyst may be pre-mixed with a water- soluble salt to form a first granule that is coated with an acidic material or mixed therewith. Generally, the bleaching catalyst is present in the first granule in the range 1 to 10 %, preferably 1 to 5 %, and most preferably 1 *. a' * : a. * * S a S a a a a.. * S a.. * a a ( - 17 - to 2%. Preferred water-soluble salts are sodium sulphate and sodium chloride, most preferred is sodium sulphate.

Alternatively, the bleaching catalyst may be applied as a suspension, preferably an aqueous suspension, to the acidic component, preferably an acidic polymer, to form a pre-mix.

The pre-mix is then used to granulate with a water-soluble salt. If the bleaching catalyst is provided as a suspension this is the preferred method of providing the acidic component.

METHOD OF COATING WITH AN ACIDIC BINDER

The coating of the co-agglomerated material with the coating material can be carried out in several ways and the process itself is not critical to the present invention.

The coating material may be sprayed on as a molten material or as a solution or dispersion in a solvent/carrier liquid that is subsequently removed by evaporation.

The coating material can also be applied as a powder coating e.g. by electrostatic techniques although this is less preferred as the adherence of powdered coating material is more difficult to achieve and can be more expensive.

Molten coating is a preferred technique for coating materials of Mpt < 80 C but is less convenient for higher Melting Point acids (i.e., > 100 C). For coating materials of Mpt > 80 C, spray on as a solution or dispersion is preferred. Organic solvents such as ethyl and isopropyl alcohol can be used to form the solutions or dispersions, * * a * a * *a *.

S. * * * SS. *, a * * * S * a *4S. I I,. * S - 18 - although this will necessitate a solvent recovery stage in order to make their use economic. However, the use of organic solvents also gives rise to safety problems such as flammability and operator safety and thus aqueous solutions or dispersions are preferred.

Within the context of the present application an acidic component that has been applied by spraying or otherwise on a granule containing the bleaching catalyst or bleaching catalyst per se will form part of the granule or granule to be formed hence the acidic component applied in this manner, in form and function, is a cogranulant or binder.

Aqueous solutions are particularly advantageous as the coating materials herein have a high aqueous solubility, provided the solution has a sufficiently low viscosity to enable it to be handled. Preferably a concentration of at least 25% by weight of the coating material in the solvent is used in order to reduce the drying/evaporation load after surface treatment has taken place. The treatment apparatus can be any of those normally used for this purpose, such as inclined rotary pans, rotary drums and fluidised beds.

All of the ingredients of the final composition may be mixed or blended in any suitable piece of equipment, such as a rotating drum. Liquid ingredients such as nonionic surfactant and perfume may be sprayed on to the surface of one or more of the constituent particles.

Appropriate choice of constituent particles is required in order to ensure that the finished composition has a bulk density of at least 350 g/l, preferably 750-1100 g/l. :

- 19 -

EXPERIMENTAL

Procedure for Storage Test Separately weighed samples of each granule/detergent powder composition were stored in open bottles at 37 C/70% RH. Each storage sample contained 7g detergent powder. Granules containing nominally 6 wt% catalyst, were all added to the detergent powder at a level of 0.075g.

The samples were removed from storage after 4 weeks and were individually dissolved in 1 litre of demineralized water, such that substantially all solutes were taken up into the aqueous solution. The residual catalyst content in the aqueous solution was measured by the following method.

The activities of the bleach component were determined at 40 00 in a H202 containing NaH2PO4.H20 pH7 buffer and Acid Blue (CAS No. 2861-02-1) as substrate using the following protocol.

Samples of 70 mg liquid were diluted in 10.00 ml MilliQ water. We added 45 p1 of this solution to an assay of 230 pL containing 20 mM H202, 75 pM Acid blue 45 and 54 mN NaH2PO4.H20 pH7 buffer.

The solutions were mixed and pre-incubated for 1 mm at 40 00. The changes in absorbance at 600 nm were measured for 8 mm at 40 00 using a spectrophotometer.

:11 * L. *. . * *.. I a *11

III I a - 20 - The absolute changes in absorbance were correlated to activities obtained with freshly prepared calibration samples.

Procedure for the Buffer Capacity Measurement Granules (l.OOg) were added to 50m1 of demineralized water in a lOOml beaker and continually stirred with a magnetic stirrer. The contents of the beaker are brought into contact with a pH probe which has been calibrated over the pH range 4 to 10. The contents of the beaker are then manually titrated with 0.01M NaOH and the pH of the contents recorded as a function of added NaOH. The volume of 0.O1M NaOH required to be added to the contents of the beaker such the contents reach a pH of 9 is defined as the buffer capacity.

Storage Results The data in the following table shows that storage stability increases with increasing buffer capacity of the granule

____________ ___________ ___________ ____________ ___________ ___________ % Cat. (%) (%)Sulph (%) Other Buffer (%) Binder ate Capacity Remainin (ml)

g after 4 week Comparati ye 3.6 (5.5) 90.9 4.7 10 ____________ CP45 __________ ___________ __________ __________ Examples ___________ __________ ___________ __________ __________ Binders and levels 6 (6)PA25 88 ---- 6.8 33 6 (6) CP13S 88 7 19 6 (12) 82 17.6 65 ___________ CP13S __________ __________ __________ __________ * *bS 4S U * * S t * U I U I * U I.' * - 21 - Co- granulate d acids ___________ __________ ___________ __________ __________ 5.5 (5.5) 80.1 (8.9) 22.6 80 CP12 maleic ____________ ___________ __________ acid __________ __________ Coatings ____ __________ ___________ _______ ________ 5.3 (5.3) 80.1 (11.3) 25.8 90 CP13S CP13S ___________ ___________ __________ Coating __________ __________ 6 (6) CP12 86 (2) 8.1 36 Soap/f att y acid ___________ ___________ _________ coating _________ _________ s.1: * . S * * S. S * : : . * . 1 I I I * ** I

Claims

- 22 - We claim: 1. A granule having a diameter in the range from 180

microns to 1000 microns, the granule comprising a transition metal catalyst and an acidic component, wherein when 1.00 gm of the granules are dissolved in ml of demineralised water to provide an acidic solution at least 6 ml of a 0.01 N solution of sodium hydroxide is required to bring the pH of the acidic solution to 9.
2. A granule comprising a transition metal catalyst according to claim 1, wherein at least 12 ml of the 0.01 N solution of sodium hydroxide is required to bring the pH of the acidic solution to 9.
3. A granule comprising a transition metal catalyst according to claim 2, wherein at least 18 ml of the 0.01 N solution of sodium hydroxide is required to bring the pH of the acidic solution to 9.
4. A granule according to any preceding claim, wherein the acidic component is a water soluble acidic polymer, said polymer having a water solubility greater than 5g/i at 20 C, a molecular weight of from 1000 to 250000, and wherein a 1% solution of said polymer has a pH of less than 7.
5. A granule according to claim 4, wherein the water soluble acidic polymer has a molecular weight of from 5000 to 150000.

I. *** * * * * . S S * * I. S * S * ** S : : ** * : * * *** S ** S I - 23 -
6. A granule according to claim 4 or 5, wherein the water soluble acidic polymer is a polymer formed from the polymerisation of an unsaturated compound containing a carboxylic acid.
7. A granule according to claim 6, wherein the water soluble acidic polymer is a polyacrylic acid.
8. A granule according to claim 7, wherein the water soluble acidic polymer is a copolymer of acrylic acid and maleic acid.
9. A granule according to any preceding claim, wherein the buffer capacity is provided through use of and acidic component selected from: an acidic binder and a cc- granulated acid.
10. A granules according to claim 9, wherein the buffer capacity is further enhanced through coating of the granule with an acidic binder material.
11. A detergent composition comprising the granule according to any one of claims 1 to 10, further comprising balance carriers and adjunct ingredients to 100%.
12. A granule according to any preceding claim, wherein the granule has been processed to form a tablet.

o: * , ** * * : . . - 24 -
13. A process for the preparation of a granule as defined in any one of claims 1 to 10, wherein the process comprising the steps of: granulating an bleaching catalyst with a component selected from the group consisting of: binder, cogranulent, and a coating, wherein the component selected is acidic.
14. A process for the preparation of a granule according to claim 13, comprising the steps of: (a) mixing a transition metal catalyst as a substantially dry solid with a solid co-granulant; and, (b) granulating with a binder.
15. A process for the preparation of a granule according to claim 13, comprising the steps of: (a) mixing a transition metal catalyst as an aqueous suspension with a binder; (b) granulating with a solid co-granulant.
16. A process for the preparation of a granule according to claim 14 or 15, wherein the solid co-granulant is a water soluble component.
17. A process for the preparation of a granule according to claim 16, wherein the solid co-granulant process comprises a component selected from: sodium sulphate and sodium chloride.

* S S S * *** SS S * I I * I * * : : : * * I * S., - 25 -
18. A process for the preparation of a granule according to claim 14 or 15, wherein the process comprises further step of coating the granule.

** *tm * *:. *.

I. S S S * * * S