PROCESS FOR MAKING PARTICULATE BLEACH ACTIVATOR COMPONENT

Abstract: The invention relates to a process for the manufacture of a particulate bleach activator component comprising the steps of: (i) preparing a mix of solids, and optionally liquids, comprising the bleach activator; (ii) extruding the mix through a die under pressure to form an extrudate, the pressure being less 25 bar; (iii) breaking the extrudate to form the particulate component; wherein the particulate bleach activator component is substantially dust-free and still disperses and releases peracid rapidly upon contact with, or immersion in, wash solution containing peroxy acid bleach at typical domestic washing temperatures.

Description: PROCESS FOR MAKING PARTICULATE BLEACH ACTIVATOR COMPONENT This invention relates to a process for the manufacture of a particulate bleach activator component. Processes for dust-free granulation are very important for hygiene-sensitive detergent components, especially bleach activators. Extrusion processes are known to yield dust- free products. US 5 318 733, granted on June 7th, 1994, discloses a granulation process for detergent compositions based upon an extrusion step operated at 25 to 200 bar. WO 9313194, published on July 8th, 1993, and WO 9202608, published on February 20th, 1992, disclose an extruder in combination with a Marumeriser for granulating bleach activators. Extrusion pressure is not specifically mentioned, although it is stated that this may be chosen to give required bulk density. EP-A-0 106 634, published on April 25th 1984, discloses an extrusion process using an axial or radial extruder. While not specifically mentioned it is known that these extruders typically operate at pressures well in excess of 25 bar. Extrusion at pressures in excess of 25 bar results in low porosity particles which often have poor solubility. This problem is particularly noticeable where the bleach activator itself has an inherently low solubility, e.g. derivatives of caproyl oxybenzene sulfonate. The object of the invention is to provide a process for the manufacture of a particulate bleach activator component comprising the steps of: (i) preparing a mix of solids, and optionally liquids, comprising the bleach activator; (ii) extruding the mix through a die under pressure to form an extrudate; (iii) breaking the extrudate to form the particulate component ,- 3 wherein the particulate bleach activator component is substantially dust-free and still disperses and releases peracid rapidly upon contact with, or immersion in, wash solution containing peroxy acid bleach at typical domestic washing temperatures. Summary of the Invention This object is achieved by operating the extrusion step at a pressure of less than 25 bar, preferably less than 20 bar. A dome extruder is particularly suitable for this. The breaking step may include a cutting or chopping step. The breaking step is preferably carried out in a rotating disk type rounding unit, for example using a Marumeriser . In a preferred embodiment of the invention the particulate component comprises from 50% to 90% by weight of the bleach activator, the particulate component is dust-free. Even more preferably the particulate component further comprises: from 5% to 30% by weight of anionic surfactant; and from 0% to 10% by weight of a binding agent and from 0 to 20% of an acidic stabilising agent; and from 0 to 5% of a hydrotrope . Particularly suitable bleach activators are caproyl oxybenzene sulfonate derivates; N,N,N 1 N 1 tetra acetylated compounds; benzoyloxybenzene sulphonate; benzoyl caprolactam; and mixtures thereof. Most suitable bleach activators are (6-octanamido-caproyl) oxybenzenesulfonate, (6-nonanamidocaproyl) oxy benzene sulfonate, (6-decanamido- caproyl) oxybenzenesulfonate, and mixtures thereof. The particulate component may optionally be further treated by a coating and/or dusting step. Detailed Description of the Invention Bleach activators as defined herein include but are not limited to the following. The solid peroxyacid bleach precursors of the present invention may comprise precursors containing one or more N- or O- acyl groups, which precursors can be selected from a wide range of classes. Suitable classes include anhydrides, esters, imides 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-836988, 864,798, 1147871 and 2143231 and imides such as are disclosed in GB-A-855735 & 1246338. A preferred precursor compounds is tetra acetyl ethylene diamine. Particularly preferred precursor compounds are the amide substituted compounds of the following general formula: R1N(R5)C(0)R2C(0)L or RIC(O)N(R5) R2C(O) L wherein R 1 is an aryl or alkaryl group with from about 1 to about 14 carbon atoms, R 2 is an alkylene, arylene, and alkarylene group containing from about 1 to 14 carbon atoms, and R 5 is H or an alkyl, aryl, or alkaryl group containing 1 to 10 carbon atoms and L can be essentially any leaving group. R 1 preferably contains from about 6 to 12 carbon atoms. R 2 preferably contains from about 4 to 8 carbon atoms. R 1 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 2 . R 2 can include alkyl, aryl, wherein said R 2 may also contain halogen, nitrogen, sulphur and other typical substituent groups or organic compounds. R 5 is preferably H or methyl. R 1 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. The leaving group, hereinafter L group, must be sufficiently reactive for the perhydrolysis reaction to occur within the optimum time frame (e.g., a wash cycle) . However, if L is too reactive, this activator will be difficult to stabilize for use in a bleaching composition. Preferred L groups are selected from the group consisting of: R 3 Y I I -O-CH=C-CH=CH 2 -0-CH=C-CH=CH 2 R 3 O Y O-C=CHR 4 , and -N—S 11 -C'H—R 4 II R 3 O and mixtures thereof, wherein R is an alkyl, aryl, or alkaryl group containing from 1 to 14 carbon atoms, R is 4 an alkyl chain containing from 1 to 8 carbon atoms, R is H or R 3, and Y is H or a solubilizing group. Any of R1, R3 4 and R may be substituted by essentially any functional group including, for example alkyl, hydroxy, alkoxy, halogen, amine, nitrosyl, amide and ammonium or alkyl ammmonium groups The preferred solubilizing groups are -SO-, M , -CO ? M , -S0 4 " M + , -N + (R 3 ) 4 X " and 0<--N(R 3 ) 3 and most preferably -SO., -M+ and -C0_-M+ wherein R3 is an alkyl chain containing from 1 to 4 carbon atoms, M is a cation which provides solubility to the bleach activator and X is an anion which provides solubility to the bleach activator. Preferably, M is an alkali metal, ammonium or substituted ammonium cation, with sodium and potassium being most preferred, and X is a. alide, hydroxide, methylsulfate or acetate anion. Preferred examples of bleach activators of the above formulae include derivatives of caproyl oxybenzene sulfonate selected from (6-octanamido- caproyl)oxybenzenesulfonate, (6-nonanamidocaproyl) oxy benzene sulfonate, (6-decanamido- caproyl) oxybenzenesulfonate, and mixtures thereof as described in EP-A-0170386. Such bleach activators have very poor water solubility (2.9g/l at 20C) and are therefore particularly suitable for processing via the present invention. Still another preferred class of bleach activator is the class of alkyl percarboxylic acid bleach precursors. Preferred alkyl percarboxylic acid precursors include nonanoyl oxy benzene sulphonate (NOBS described in US 4,412,934) and 3 , 5, 5-tri-methyl hexanoyl oxybenzene sulfonate (ISONOBS described in EP120,591) and salts thereof . Mixture of any of the peroxyacid bleach precursor, herein before described, may also be used. The peroxyacid bleach precursors are normally incorporated at a level of from 20% to 95% preferably 50% to 90% by weight of the particulate bleach activator component and most preferably at least 60% by weight thereof. In absolute terms the peroxyacid bleach precursor is typically from 1% to 20% by weight, more preferably from 1% to 10% by weight, most preferably from 1% to 7% by weight of the detergent compositions. The particles of particulate peroxyacid bleach activator component preferably have a particle size of from 250 micrometers to 2000 micrometers. These peroxyacid bleach precursors can be partially replaced by preformed peracids such as N,N phthaloylaminoperoxy acid (PAP) , nonyl amide of peroxyadipic acid (NAPAA) , 1,2 diperoxydodecanedioic acid (DPDA) and trimethyl ammonium propenyl imidoperoxy mellitic acid (TAPIMA) . Surfactants are useful in the particulate components of the present invention in particular as solubilising agents. Nonlimiting examples of surfactants useful herein include the conventional C11-C18 alkyl benzene sulphonates ("LAS") and primary, branched-chain and random C10-C20 alkyl sulphates ("AS") , the C10-C18 secondary (2,3) alkyl sulphates of the formula CH 3 (CH 2 ) x (CHOSO3 " M + ) CH 3 and CH 3 (CH 2 ) y (CHOSO3 " M + ) CH CH 3 where x and (y+1) are integers of at least 7, preferably at least about 9, and M is a water-solubilising cation, especially sodium, unsaturated sulphates such as oleyl sulphate, the C10-C18 alkyl alkoxy sulphates ("AExS" ; especially EO 1-7 ethoxy sulphates) , C10-C18 alkyl alkoxy carboxylates (especially EO 1-7 ethoxy carboxylates) , the C10-C18 glycerol ethers, the C10-C18 alkyl polyglycosides and their corresponding sulphated polyglycosides, the C12-C18 alpha-sulphonated fatty acid esters, methyl ester sulphonate ("MES") and oleoyl sarcosinate. In addition to anionic surfactants, nonionic, cationic, amphoteric and/or zwitterionic surfactants may optionally be incorporated into the particulate component. The solubilising effect of the surfactant can be further enhanced by addition of a hydrotrope . Hydrotropes suitable for use herein are selected from the group lower alkyl aryl sulphonate salts, C 6 -C 12 alkanols, C]_-Cg carboxyiic sulphate or sulphonate salts, urea, C± -C^ hydrocarboxylates, C^ -C^ carboxylates and C 2 -C4 diacids and mixtures thereof. Suitable lower alkyl aryl sulphonates are preferably C7-C9 alkyl aryl sulphonates and include sodium, potassium, calcium and ammonium xylene sulphonates, sodium, potassium, calcium and ammonium toluene sulphonates, sodium, potassium, calcium and ammonium cumene sulphonate, and sodium, potassium, calcium and ammonium napthalene sulphonates and mixtures thereof. Suitable CI ~ C Q carboxyiic sulphate or sulphonate salts are any water soluble salts or organic compounds comprising 1 to 8 carbon atoms (exclusive of substituent groups) , which are substituted with sulphate or sulphonate and have at least one carboxyiic group. The substituted organic compound may be cyclic, acylic or aromatic, i.e. benzene derivatives. Preferred alkyl compounds have from 1 to 4 carbon atoms substiuted with sulphate or sulphonate and have from 1 to 2 carboxyiic groups. Examples of suitable hydrotropes include sulphosuccinate salts, sulphophthalic salts, sulphoacetic salts, m-sulphobenzoic acid salts and diesters sulphosuccinates, preferably the sodium or potassium salts as disclosed in US 3 915 903. Suitable C1-C hydrocarboxylates, C1-C4 carboxylates for use herein include acetates and propionates and citrates. Suitable C 2 -C4 diacids for use herein include succinic, glutaric and adipic acids. Other compounds which deliver hydrotropic effects suitable for use herein as a hydrotrope include Cg-C^ alkanols and urea. Preferred hydrotropes for use herein are sodium, potassium, calcium and ammonium cumene sulphonate, sodium, potassium, calcium and ammonium xylene sulphonate, sodium, potassium, calcium and ammonium toluene sulphonate and mixtures thereof. Most preferred is sodium toluene sulphonate. According to the present invention the compositions comprise more up to 5% of hydrotrope, preferably from 0.5% to 3% . Acid are useful in the particulate components of the present invention in particular as stabilising agents. Suitable acids include fatty acids, glycolic acid, glutaric acid, citric acid and polymeric carboxyiic acids. Binding agents are useful in the particulate components of the present invention. Suitable binding agents include starch, cellulose and cellulose derivatives (e.g. Na-CMC) , sugar and film-forming polymers such as polymeric carboxyiic acid, including copolymers, polyvinyl pyrrolidone, polyvinyl acetate, . Co-polymers of acrylic and maleic acid are particularly preferred. Extrusion Extrusion is an essential step of the present invention. Any extruder which can be operated with the required composition at a pressure of less than 25 bar is suitable for use in the present invention. Dome extruders are highly preferred including single- and twin-screw extruders such as the TDG 110 manufactured by Fuji Paudal . In such extruders material is conveyed by the screws to an end die plate which is in the form of one or two perforated hemispheres. The diameter of the perforations is selected to give the desired final particle size. Radial extruders may also be suitable if they can be operated within the required pressure range. Breaking The extrudate must be broken into short lengths . This step is referred to herein as "breaking" . Depending upon the nature of the extrudate it may break up into short lengths without the need for any mechanical action, or it may be cut or chopped by a mechanical device or knife. A preferred means of breaking is via a rotating device (e.g. a baffled drum) or an agitating device (e.g. a dynamic mixer) . A particularly preferred means of breaking is via a rotating disk type spheronising unit such as Model 700 manufactured by Cale.va and the Marumeriser" model QJ 1000 manufactured by Fuji Paudel. These units consist of a grooved horizontal plate rotating at high speed within a stationary vertical cylinder. Frictional and centrifugal forces within the unit break the extrudates into short lengths . The broken extrudates are then preferably re-shaped by further action within the spheronising unit to form cylinders with rounded edges. Even more preferably the extrudates are further shaped into dumb-bells, ellipses and most preferably into spheres. The ratio of the longest to shortest dimension of the final extrudate is preferably less than 10:1, more preferably less than 5:1, and most preferably less than 1.5:1. Mean particle size is preferably in the range of from 0.25 mm to 2 mm. Drying and Coating / Dusting In an optional finishing step the particulate component may be dried, preferably in a fluid-bed dryer and optionally coated or dusted to improve stability and/or handling properties. Suitable coating agents include film forming materials such as synthetic polymers (such as copolymers of acrylic and maleic acid, polyvinyl alcohol, polyvinyl pyrrolidone polyethylene glycol) , natural polymers ( such as Cellulose derivatives e.g. Na-CMC and Hydroxy propyl methyl cellulose) and surfactants such as Ethoxylated Alcohols . Suitable dusting agents include zeolites, fumed and precipitated silicas. The coating and dusting steps can be carried out in any suitable low shear mixing device, such as a drum mixer or a Loedige® ploughshare mixer. Finished bleach activator particulate component The finished bleach activator particulate component is "dus -free". By dus -free what is meant herein is that the particle size of the particulate component less than 250 micrometers is less than 5%, preferably less than 1% and more preferably less than 0.5% by weight. The particle size fraction is measured using a sieve with 250 micrometers (Tyler mesh 60) . Furthermore by dust-free the particle must have sufficient resistance to prevent dust formation in handling and transportation, The resistance of the bleach activator particulate to form dust upon handling is measured by a Heubach dus -meter (manufactured by Heubach Engineering GmbH, D-33 4 Langelsheim, Germany) and is such that less than lOO g of dust per gram of bleach activator particles is generated in the test. More preferably the amount of dust generated is less than 50mg/g and even more preferably less than 5mg/g. The principle of the Heubach dustmeter is that four steel balls are placed together with the sample of bleach activator particles into a sample container. The balls stress_the sample by means of agitation. Simultaneously air is sucked through the sample and dust particles created by attrition are collected on a filter paper and weighed and the result is expressed as mg of dust per gram of bleach activator particles in the original sample. Preferred bulk density of the particulate component is greater than 300 g/1, even more preferably from 600 to 1000 g/l. In a particular embodiment of the present invention the bleach activator entering the extrusion step has a medium particle size of less than 35 micrometers, preferably from 1 to 30 micrometers and more preferably from 5 to 20 micrometers. These small particle sizes can be achieved by any particle size reduction technique, such as grinding. EXAMPLES Examples 1-7 The following particulate compositions were made Example 1 Example 2 Example 3 NACA-OBS 73 69 69 Citric acid 14 13 13 LAS - - 11 C12/14 AE3S 5 10 - Acrylic/maleic 6 6 5 copolymer Water 2 2 2 Example 4 Example 5 Example 6 Example 7 NACA-OBS 76 79 74.5 TAED 76 Citric acid 5 5 10 LAS 11 13 11 10 Acrylic/maleic 6 6 copolymer STS 1 C12/14 AE3 0.5 CMC 2 Water 2 NACA-OBS is nonyl amido caproyl oxy benzene sulphonate; TAED is tetra acetyl ethylene diamine; LAS is sodium linear alkyl benzene sulphonate; C12/14 AE3S is ethoxylated alkyl sulphate having a carbon chain length of predominantly C12/C14 and a average of 3 ethoxy groups per molecule . C12/14 AE3 is an ethoxylated alcohol having a carbon chain length of predominantly C12/C14 and an average of 3 ethoxy groups per molecule . STS is sodium toluene sulphonate. CMC is carboxymethyl cellulose All of the levels are percentages by weight unless otherwise specified. In each of examples 1 to 7 the bleach activator (i.e. NACA- OBS or TAED) was premixed with citric acid (where present) , AE3S or LAS (where present) and either an aqueous solution (40% active) of the acrylic maleic copolymer, or CMC powder, in a Loedige FM mixer. Optionally water is added to help plasticize the mix and, in the case of CMC to hydrate and activate the binder. The premix was then fed into a dome extruder (Fuji Paudal Model DGL-1) having a die with 0.8 mm orifices and extruded at a pressure of about 20 bar. The resulting extrudate was then fed into a rotating disc spheroniser (Fuji Paudal QJ-400) where they were broken down into short lengths and formed into substantially spherical particles. The particles were then dried in a Niro vibrating fluid-bed dryer resulting in crisp, free-flowing dust free particles with a particle size range of from 0.25 mm to 2.00 mm and a Heubach dust measurement of less than lOOmg/g. Examples 8 to 14 The particles produced in each of Examples 1 to 7 were taken and coated in a drum mixer with 0.4 parts of C12/14AE3 surfactant and then further dusted with 1 part of Zeolite in a second drum mixer. The resultant particles remained crisp and free-flowing and showed improved resistance to dust-generation as demonstrated by a reduction in Heubach dust value from 35mg/g (un-coated) to 12 mg/g.

Claims: CLAIMS 1. A process for the manufacture of a particulate bleach activator component comprising the steps of: (i) preparing a mix of solids, and optionally liquids, comprising the bleach activator; (ii) extruding the mix through a die under pressure to form an extrudate; (iii) breaking the extrudate to form the particulate component ; characterised in that the pressure of the extrusion step is less than 25 bar. 2. A process according to claim 1 wherein the breaking step comprises spheronisation to form the particulate component. 3. A process according to claim 1 wherein the breaking step comprises cutting or chopping to form the particulate component . 4. A process according to any of claims 1 to 3 wherein the particulate component comprises from 50% to 90% by weight of the bleach activator and wherein the particulate component is dust-free. 5. A process according to claim 4 wherein the bleach activator is selected from the group consisting of caproyl oxybenzene sulfonate derivatives; N J J N^- 1 tetra acetylated compounds; acyl oxy benzene sulphonates; benzoyloxybenzene sulphonate; benzoyl caprolactam; or mixtures thereof. 6. A process according to claim 5 wherein bleach activator is a derivative of caproyl oxybenzene sulfonate selected from the group consisting of (6-octanamido- caproyl)oxybenzenesulfonate, (6-nonanamidocaproyl) oxy benzene sulfonate, (6-decanamido- caproyl) oxybenzenesulfonate, and mixtures thereof, preferably the sodium salt. 7. A process according to claim 4 wherein the particulate component further comprises: from 5% to 30% by weight of surfactant; from 0% to 10% by weight of a binding agent; from 0% to 20% by weight of an acidic stabilising agent; and from 0% to 5% by weight of a hydrotrope. 8. A process according to claim 4 wherein the particulate component is further treated by a coating and/or dusting step.

Inventors: SHARMA SANJEEV, YORK DAVID WILLIAM, SHARMA, SANJEEV, YORK, DAVID, WILLIAM
Applicants: PROCTER & GAMBLE, SHARMA SANJEEV, YORK DAVID WILLIAM, SHARMA, SANJEEV, THE PROCTER & GAMBLE COMPANY, YORK, DAVID, WILLIAM
Application year: 1997
Main classification: C11D11
IPC codes: C11D3, C11D11, C11D17