Process for preparing laundry detergent particles

Abstract

 A process for the preparation of a coated detergent particle having perpendicular dimensions x, y and z, wherein x is from 1 to 2 mm, y is from 2 to 8 mm, and z is from 2 to 8 mm, wherein the process comprises the following steps:
(i) roller compacting from 40 to 90 wt % of a surfactant selected from: anionic surfactant and non-ionic surfactant, wherein the surfactant has a hardness from 1 MPa to 100 MPa when compacting and the roller compacter having a void commensurate with the size of the particle before coating;
(ii) coating the roller compacted material with from 1 to 40 wt % of water soluble inorganic salts in the form of an aqueous solution; and,
(iii) removing water from the product of step (ii) by application of a aeration process selected from: a fluidized bed and a drum.

Description

Field of Invention

[0001] The present invention relates to a process for the preparation of large laundry detergent particles.

Background of Invention

[0002] WO9932599 describes a method of manufacturing laundry detergent particles, being an extrusion method in which a builder and surfactant, the latter comprising as a major component a sulphated or sulphonated anionic surfactant, are fed into an extruder, mechanically worked at a temperature of at least 40 °C, preferably at least 60°C, and extruded through an extrusion head having a multiplicity of extrusion apertures. In most examples, the surfactant is fed to the extruder along with builder in a weight ratio of more than 1 part builder to 2 parts surfactant. The extrudate apparently required further drying. In Example 6, PAS paste was dried and extruded. Such PAS noodles are well known in the prior art. The noodles are typically cylindrical in shape and their length exceeds their diameter, as described in example 2.

[0003] US 7,022,660 discloses a process for the preparation of a detergent particle having a coating.

Summary of the Invention

[0004] The present invention provides a coated detergent particle that is a concentrated formulation with more surfactant than inorganic solid. Only by having the coating encasing the surfactant which is soft can one have such a particulate concentrate where the unit dose required for a wash is reduced. Adding solvent to the core would result by converting the particle into a liquid formulation. On the other hand, having a greater amount of inorganic solid would result in a less concentrated formulation; a high inorganic content would take one back to conventional low surfactant concentration granular powder. The coated detergent particle of the present invention sits in the middle of the two conventional (liquid and granular) formats.

[0005] In one aspect the present invention provides process for the preparation of a coated detergent particle having perpendicular dimensions x, y and z, wherein x is from 1 to 2 mm, y is from 2 to 8mm (preferably 3 to 8 mm), and z is from 2 to 8 mm (preferably 3 to 8 mm), wherein the process comprises the following steps:

(i) roller compacting from 40 to 90 wt %, preferably 50 to 90 wt%, of a surfactant selected from: anionic surfactant; and, non-ionic surfactant, wherein the surfactant has a hardness from 1 MPa to 100 MPa, preferably from 2 MPa to 20 MPa, when compacting and the roller compacter having a void commensurate with the size of the uncoated detergent particle;

(ii) coating the roller compacted material with from 1 to 40 wt % preferably 20 to 40 wt %, of water soluble inorganic salts in the form of an aqueous solution; and,

(iii) removing water from the product of step (ii) by application of a aeration process selected from: a fluidized bed; and, a drum.

[0006] The amount of water removed in step (iii) is commensurate with the amount of water added in step (ii); some water from step (ii) will likely be retained, for example as hydrated salts.

[0007] The amount of water removed in step (iii) is preferably from 50 to 100 wt % of the water added to the uncoated detergent particle in step (ii).

[0008] Unless otherwise stated all wt % refer to the total percentage in the particle as dry weights.

Detailed Description of the Invention

Roller compaction

[0009] Compacting, briquetting and pelleting with roll type presses can be used to form shaped particles of a desired size and shape.

Briquettor

[0010] The product is densified by a screw feed arrangement and two, counter rotating rolls gently shape the material. The profile of the rolls is such that precise shapes can be produced without material sticking to the rolls. Size and shape can be adapted to the application.

[0011] The product remains within the forming zone of the machine for only a short time and the product is produced at ambient temperature.

Pelletizer

[0012] Underneath the feed hopper a pair of toothed rolls counter rotate. The rolls draw the product in and press it out through the nozzles between the teeth. Granulating rolls with different nozzles. The press nozzles can be bored directly into the press rolls or the rolls can be equipped with exchangeable nozzle plates.

Coating

Water soluble inorganic salts

[0013] The water soluble inorganic salts are preferably selected from sodium carbonate, sodium chloride, sodium silicate and sodium sulphate, or mixtures thereof, most preferably 70 to 100 wt % sodium carbonate. The water soluble inorganic salt is present as a coating on the particle. The water soluble inorganic salt is preferably present at a level that reduces the stickiness of the laundry detergent particle to a point where the particles are free flowing.

[0014] It will be appreciated by those skilled in the art that multiple layered coatings, of the same or different coating materials, could be applied, but a single coating layer is preferred, for simplicity of operation, and to maximise the thickness of the coating. The amount of coating should lay in the range 1 to 40 wt % of the particle, preferably 20 to 40 wt %, even more preferably 25 to 35 wt % for the best results in terms of anti-caking properties of the detergent particles.

[0015] The coating is applied to the surface of the surfactant core, by crystallisation from an aqueous solution of the water soluble inorganic salt. The aqueous solution preferably contains greater than 50g/L, more preferably 200 g/L of the salt. An aqueous spray-on of the coating solution in a fluidised bed has been found to give good results and may also generate a slight rounding of the detergent particles during the fluidisation process. Drying and/or cooling may be needed to finish the process.

[0016] By coating the large detergent particles of the current invention the thickness of coating obtainable by use of a coating level of say 5 wt% is much greater than would be achieved on typically sized detergent granules (0.5-2mm diameter sphere).

[0017] For optimum dissolution properties, this surface area to volume ratio must be greater than 3 mm^-1. However, the coating thickness is inversely proportional to this coefficient and hence for the coating the ratio "Surface area of coated particle" divided by "Volume of coated particle" should be less than 15 mm^-1.

SHAPE

[0018] Preferably the coated laundry detergent particle is curved.

[0019] The coated laundry detergent particle may be lenticular (shaped like a whole dried lentil), an oblate ellipsoid, where z and y are the equatorial diameters and x is the polar diameter; preferably y = z.

[0020] The coated laundry detergent particle may be shaped as a disc.

[0021] Preferably the coated laundry detergent particle does not have hole; that is to say, the coated laundry detergent particle does not have a conduit passing there though that passes through the core, i.e., the coated detergent particle has a topologic genus of zero.

[0022] This is reflected in the fact that the void in the roller or rollers is commensurate with the size of the particle. The shape and size of the uncoated detergent particle will likely change after formation due to water migration and fluidity of the particle.

CORE

SURFACTANT

[0023] The hardness at the point of compaction is an interplay between the surfactant composition and the amount of water in the material being rolled. Some surfactant systems have to have relatively low water content to have the requited threshold of hardness other surfactant systems can tolerate larger water content.

[0024] Hardness was measured in the following manner. A rigid probe of spherical shape is pressed into the test material at a particular velocity until a maximum load is reached. After a dwell - or hold-time at this load, the indenter is withdrawn from the material at a constant velocity. Once the raw data are processed, the indentation data consist of the compressive load on the indenter, W [N], and the total penetration depth, ht [m], into the material as a function of time during the three phases of the experiment; namely the loading phase, the hold phase and the unloading phase. The latter phase contains information about the adhesive behaviour. The indentation hardness of a material, H[Pa], is commonly defined as the mean contact pressure under the indenter. Hence:


where a_c [m], is the contact radius.

[0025] In the case of high active granules the material is stored in a chamber which is kept at a constant 5%RH until they have stabilised. A Novasina water activity instrument is used to check the RH of the granules. At this point the granular material is loaded into a 20mm diameter die and compressed with a load ok 10kN such that a "compact" is formed. This compact then becomes the test sample for a sphere indentation test which is carried out under the following conditions. A 3mm diameter synthetic sapphire sphere is pressed into the compact at a rate of 25µm/s (check on Monday) until a load of 1 N is achieved. This load is then held constant for 30 seconds (referred to as a creep segment) and then the sphere is removed from the compact at a rate of 10µm/s. The force and displacements are captured at a rate of 25Hz during the course of each experiment and stored for future analysis. A standard series of tests would involve measuring the H values at 20°C and 5%RH. More compacts are stored at 18%RH, 33%RH and 50%RH and once stable at those conditions they are then measured, again at 20°C but with the RH kept at these conditions during the course of each test.

[0026] The coated laundry detergent particle comprises between 40 to 90 wt%, preferably 50 to 90 wt% of a surfactant, most preferably 70 to 90 wt %. In general, the nonionic and anionic surfactants of the surfactant system may be chosen from the surfactants described "Surface Active Agents" Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, in the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981. Preferably the surfactants used are saturated.

Anionic Surfactants

[0027] Suitable anionic detergent compounds which may be used are usually water-soluble alkali metal salts of organic sulphates and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates, especially those obtained by sulphating higher C₈ to C₁₈ alcohols, produced for example from tallow or coconut oil, sodium and potassium alkyl C₉ to C₂₀ benzene sulphonates, particularly sodium linear secondary alkyl C₁₀ to C₁₅ benzene sulphonates; and sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum. Most preferred anionic surfactants are sodium lauryl ether sulfate (SLES), particularly preferred with 1 to 3 ethoxy groups, sodium C₁₀ to C₁₅ alkyl benzene sulphonates and sodium C₁₂ to C₁₈ alkyl sulphates. Also applicable are surfactants such as those described in EP-A-328 177 (Unilever), which show resistance to salting-out, the alkyl polyglycoside surfactants described in EP-A-070 074, and alkyl monoglycosides. The chains of the surfactants may be branched or linear.

[0028] Soaps may also be present. The fatty acid soap used preferably contains from about 16 to about 22 carbon atoms, preferably in a straight chain configuration. The anionic contribution from soap is preferably from 0 to 30 wt% of the total anionic.

[0029] Preferably, at least 50 wt % of the anionic surfactant is selected from: sodium C₁₁ to C₁₅ alkyl benzene sulphonates; and, sodium C₁₂ to C₁₈ alkyl sulphates. Even more preferably, the anionic surfactant is sodium C₁₁ to C₁₅ alkyl benzene sulphonates.

[0030] Preferably the anionic surfactant is present in the coated laundry detergent particle at levels between 15 to 85 wt%, more preferably 50 to 80wt% on total surfactant.

Nonionic Surfactants

[0031] Suitable nonionic detergent compounds which may be used include, in particular, the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Preferred nonionic detergent compounds are C₆ to C₂₂ alkyl phenol-ethylene oxide condensates, generally 5 to 25 EO, i.e. 5 to 25 units of ethylene oxide per molecule, and the condensation products of aliphatic C₈ to C₁₈ primary or secondary linear or branched alcohols with ethylene oxide, generally 5 to 50 EO. Preferably, the non-ionic is 10 to 50 EO, more preferably 20 to 35 EO. Alkyl ethoxylates are particularly preferred.

[0032] Preferably the nonionic surfactant is present in the coated laundry detergent particle at levels between 5 to 75 wt% on total surfactant, more preferably 10 to 40 wt% on total surfactant.

[0033] Cationic surfactant may be present as minor ingredients at levels preferably between 0 to 5 wt% on total surfactant.

[0034] Preferably all the surfactants are mixed together before being dried. Conventional mixing equipment may be used. The surfactant core of the laundry detergent particle may be formed by extrusion or roller compaction and subsequently coated with an inorganic salt.

Calcium Tolerant Surfactant System

[0035] In another aspect the surfactant system used is calcium tolerant and this is a preferred aspect because this reduces the need for builder.

[0036] Surfactant blends that do not require builders to be present for effective detergency in hard water are preferred. Such blends are called calcium tolerant surfactant blends if they pass the test set out hereinafter. However, the invention may also be of use for washing with soft water, either naturally occurring or made using a water softener. In this case, calcium tolerance is no longer important and blends other than calcium tolerant ones may be used.

[0037] Calcium-tolerance of the surfactant blend is tested as follows:

The surfactant blend in question is prepared at a concentration of 0.7 g surfactant solids per litre of water containing sufficient calcium ions to give a French hardness of 40 (4 x 10^-3 Molar Ca²⁺). Other hardness ion free electrolytes such as sodium chloride, sodium sulphate, and sodium hydroxide are added to the solution to adjust the ionic strength to 0.05M and the pH to 10. The adsorption of light of wavelength 540 nm through 4 mm of sample is measured 15 minutes after sample preparation. Ten measurements are made and an average value is calculated. Samples that give an absorption value of less than 0.08 are deemed to be calcium tolerant.

[0038] Examples of surfactant blends that satisfy the above test for calcium tolerance include those having a major part of LAS surfactant (which is not of itself calcium tolerant) blended with one or more other surfactants (co-surfactants) that are calcium tolerant to give a blend that is sufficiently calcium tolerant to be usable with little or no builder and to pass the given test. Suitable calcium tolerant co-surfactants include SLES 1-7EO, and alkyl-ethoxylate nonionic surfactants, particularly those with melting points less than 40°C.

[0039] A LAS/SLES surfactant blend has a superior foam profile to a LAS nonionic surfactant blend and is therefore preferred for hand washing formulations requiring high levels of foam. SLES may be used at levels of up to 30 wt% of the surfactant blend.

Water Soluble Inorganic Salts

[0040] The water-soluble inorganic salts are preferably selected from sodium carbonate, sodium chloride, sodium silicate and sodium sulphate, or mixtures thereof, most preferably, 70 to 100 wt% sodium carbonate on total water-soluble inorganic salts. The water-soluble inorganic salt is present as a coating on the particle. The water-soluble inorganic salt is preferably present at a level that reduces the stickiness of the laundry detergent particle to a point where the particles are free flowing.

[0041] It will be appreciated by those skilled in the art that while multiple layered coatings, of the same or different coating materials, could be applied, a single coating layer is preferred, for simplicity of operation, and to maximise the thickness of the coating. The amount of coating should lay in the range 1 to 40 wt% of the particle, preferably 20 to 40 wt%, more preferably 25 to 35 wt% for the best results in terms of anti-caking properties of the detergent particles.

[0042] The coating is preferably applied to the surface of the surfactant core, by deposition from an aqueous solution of the water soluble inorganic salt. In the alternative coating can be performed using a slurry. The aqueous solution preferably contains greater than 50g/L, more preferably 200 g/L of the salt. An aqueous spray-on of the coating solution in a fluidised bed has been found to give good results and may also generate a slight rounding of the detergent particles during the fluidisation process. Drying and/or cooling may be needed to finish the process.

[0043] A preferred calcium tolerant coated laundry detergent particle comprises 15 to 100 wt% on surfactant of anionic surfactant of which 20 to 30 wt% on surfactant is sodium lauryl ether sulphate.

The coated laundry detergent particle

[0044] Preferably, the coated laundry detergent particle comprises from 10 to 100 wt %, more preferably 50 to 100 wt %, even more preferably 80 to 100 wt %, most preferably 90 to 100 wt % of a laundry detergent formulation in a package.

[0045] The package is that of a commercial formulation for sale to the general public and is preferably in the range of 0.01 kg to 5 kg, preferably 0.02 kg to 2 kg, most preferably 0.5 kg to 2 kg. The smallest package of a commercial formulation for sale may resemble a small tube with a single or a small number of doses, e.g., 5 doses.

[0046] Preferably, the coated laundry detergent particle is such that at least 90 to 100 % of the coated laundry detergent particles in the in the x, y and z dimensions are within a 20 %, preferably 10%, variable from the largest to the smallest coated laundry detergent particle.

Water content

[0047] The particle preferably comprises from 0 to 15 wt % water, more preferably 0 to 10 wt %, most preferably from 1 to 5 wt % water, at 293K and 50% relative humidity. This facilitates the storage stability of the particle and its mechanical properties.

Other Adjuncts

[0048] The adjuncts as described below may be present in the coating or the core. These may be in the core or the coating.

Fluorescent Agent

[0049] The coated laundry detergent particle preferably comprises a fluorescent agent (optical brightener). Fluorescent agents are well known and many such fluorescent agents are available commercially. Usually, these fluorescent agents are supplied and used in the form of their alkali metal salts, for example, the sodium salts. The total amount of the fluorescent agent or agents used in the composition is generally from 0.005 to 2 wt %, more preferably 0.01 to 0.1 wt %. Suitable Fluorescer for use in the invention are described in chapter 7 of Industrial Dyes edited by K.Hunger 2003 Wiley-VCH ISBN 3-527-30426-6.

[0050] It is preferred that the coated laundry detergent particle does not contain a peroxygen bleach, e.g., sodium percarbonate, sodium perborate, and peracid.

Polymers

[0051] The composition may comprise one or more further polymers. Examples are carboxymethylcellulose, poly (ethylene glycol), poly(vinyl alcohol), polyethylene imines, ethoxylated polyethylene imines, water soluble polyester polymers polycarboxylates such as polyacrylates, maleic/acrylic acid copolymers and lauryl methacrylate/acrylic acid copolymers.

Enzymes

[0052] One or more enzymes are preferred present in a composition of the invention.

[0053] Preferably the level of each enzyme is from 0.0001 wt% to 0.5 wt% protein.

[0054] Especially contemplated enzymes include proteases, alpha-amylases, cellulases, lipases, peroxidases/oxidases, pectate lyases, and mannanases, or mixtures thereof.

[0055] Suitable lipases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Examples of useful lipases include lipases from Humicola (synonym Thermomyces), e.g. from H. Ianuginosa (T. Ianuginosus) as described in EP 258 068 and EP 305 216 or from H. insolens as described in WO 96/13580, a Pseudomonas lipase, e.g. from P. alcaligenes or P. pseudoalcaligenes (EP 218 272), P. cepacia (EP 331 376), P. stutzeri (GB 1,372,034), P. fluorescens, Pseudomonas sp. strain SD 705 (WO 95/06720 and WO 96/27002), P. wisconsinensis (WO 96/12012), a Bacillus lipase, e.g. from B. subtilis (Dartois et al. (1993), Biochemica et Biophysica Acta, 1131, 253-360), B. stearothermophilus (JP 64/744992) or B. pumilus (WO 91/16422).

[0056] Other examples are lipase variants such as those described in WO 92/05249, WO 94/01541, EP 407 225, EP 260 105, WO 95/35381, WO 96/00292, WO 95/30744, WO 94/25578, WO 95/14783, WO 95/22615, WO 97/04079 and WO 97/07202, WO 00/60063, WO 09/107091 and WO09/111258.

[0057] Preferred commercially available lipase enzymes include Lipolase™ and Lipolase Ultra™, Lipex™ (Novozymes A/S) and Lipoclean™.

[0058] The method of the invention may be carried out in the presence of phospholipase classified as EC 3.1.1.4 and/or EC 3.1.1.32. As used herein, the term phospholipase is an enzyme which has activity towards phospholipids.

[0059] Phospholipids, such as lecithin or phosphatidylcholine, consist of glycerol esterified with two fatty acids in an outer (sn-1) and the middle (sn-2) positions and esterified with phosphoric acid in the third position; the phosphoric acid, in turn, may be esterified to an amino-alcohol. Phospholipases are enzymes which participate in the hydrolysis of phospholipids. Several types of phospholipase activity can be distinguished, including phospholipases A₁ and A₂ which hydrolyze one fatty acyl group (in the sn-1 and sn-2 position, respectively) to form lysophospholipid; and lysophospholipase (or phospholipase B) which can hydrolyze the remaining fatty acyl group in lysophospholipid. Phospholipase C and phospholipase D (phosphodiesterases) release diacyl glycerol or phosphatidic acid respectively.

[0060] Suitable proteases include those of animal, vegetable or microbial origin. Microbial origin is preferred. Chemically modified or protein engineered mutants are included. The protease may be a serine protease or a metallo protease, preferably an alkaline microbial protease or a trypsin-like protease. Preferred commercially available protease enzymes include Alcalase™, Savinase™, Primase™, Duralase™, Dyrazym™, Esperase™, Everlase™, Polarzyme™, and Kannase™, (Novozymes A/S), Maxatase™, Maxacal™, Maxapem™, Properase™, Purafect™, Purafect OxP™, FN2™, and FN3™ (Genencor International Inc.).

[0061] The method of the invention may be carried out in the presence of cutinase. classified in EC 3.1.1.74. The cutinase used according to the invention may be of any origin. Preferably cutinases are of microbial origin, in particular of bacterial, of fungal or of yeast origin.

[0062] Suitable amylases (alpha and/or beta) include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Amylases include, for example, alpha-amylases obtained from Bacillus, e.g. a special strain of B. licheniformis, described in more detail in GB 1,296,839, or the Bacillus sp. strains disclosed in WO 95/026397 or WO 00/060060. Commercially available amylases are Duramyl™, Termamyl™, Termamyl Ultra™, Natalase™, Stainzyme™, Fungamyl™ and BAN™ (Novozymes A/S), Rapidase™ and Purastar™ (from Genencor International Inc.).

[0063] Suitable cellulases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Suitable cellulases include cellulases from the genera Bacillus, Pseudomonas, Humicola, Fusarium, Thielavia, Acremonium, e.g. the fungal cellulases produced from Humicola insolens, Thielavia terrestris, Myceliophthora thermophila, and Fusarium oxysporum disclosed in US 4,435,307, US 5,648,263, US 5,691,178, US 5,776,757, WO 89/09259, WO 96/029397, and WO 98/012307. Commercially available cellulases include Celluzyme™, Carezyme™, Endolase™, Renozyme™ (Novozymes A/S), Clazinase™ and Puradax HA™ (Genencor International Inc.), and KAC-500(B)™ (Kao Corporation).

[0064] Suitable peroxidases/oxidases include those of plant, bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Examples of useful peroxidases include peroxidases from Coprinus, e.g. from C. cinereus, and variants thereof as those described in WO 93/24618, WO 95/10602, and WO 98/15257. Commercially available peroxidases include Guardzyme™ and Novozym™ 51004 (Novozymes A/S).

[0065] Further enzymes suitable for use are disclosed in WO2009/087524, WO2009/090576, WO2009/148983 and WO2008/007318.

Enzyme Stabilizers

[0066] Any enzyme present in the composition may be stabilized using conventional stabilizing agents, e.g., a polyol such as propylene glycol or glycerol, a sugar or sugar alcohol, lactic acid, boric acid, or a boric acid derivative, e.g., an aromatic borate ester, or a phenyl boronic acid derivative such as 4-formylphenyl boronic acid, and the composition may be formulated as described in e.g. WO 92/19709 and WO 92/19708.

[0067] Where alkyl groups are sufficiently long to form branched or cyclic chains, the alkyl groups encompass branched, cyclic and linear alkyl chains. The alkyl groups are preferably linear or branched, most preferably linear.

[0068] The indefinite article "a" or "an" and its corresponding definite article "the" as used herein means at least one, or one or more, unless specified otherwise. The singular encompasses the plural unless otherwise specified.

[0069] Sequesterants may be present in the coated laundry detergent particles.

[0070] It is preferred that the coated detergent particle has a core to shell ratio of from 4 to 1:1, most preferably 3 to 1.5:1; the optimal ratio of core to shell is 2:1.

EXPERIMENTAL

Example 1: (particle manufacture)

Preparation of core

[0071] 2000 g of a dry surfactant blend that had been dried from Unger Ufasan 65 LAS, Stepan Steol CFAS70 PAS paste and Stepan BES70 SLES paste in the ratio of 56.5 parts LAS, 15.2 parts PAS and 28.3 parts SLES (on a dry basis). Was added to a twin roller device and pressed into cylindrical shapes.

Coating of Particle

[0072] Material of above 764g was charged to the fluidising chamber of a Strea 1 laboratory fluid bed drier (Aeromatic-Fielder AG) and spray coated using 1069g of a solution containing 320.7g of sodium carbonate in 748.3g of water, using a top-spray configuration.

[0073] The coating solution was fed to the spray nozzle of the Strea 1 via a peristaltic pump (Watson-Marlow model 101 U/R) at an initial rate of 3.3g/min, rising to 9.1g/min during the course of the coating trial.

[0074] The Fluid bed coater was operated with an initial air inlet air temperature of 55°C increasing to 90°C during the course of the coating trial whilst maintaining the outlet temperature in the range 45-50°C throughout the coating process.

Claims

1. A process for the preparation of a coated detergent particle having perpendicular dimensions x, y and z, wherein x is from 1 to 2 mm, y is from 2 to 8mm, and z is from 2 to 8 mm, wherein the process comprises the following steps:

(i) roller compacting from 40 to 90 wt % of a surfactant selected from: anionic surfactant; and, non-ionic surfactant, wherein the surfactant has a hardness from 1 MPa to 100 MPa when compacting and the roller compacter having a void commensurate with the size of the particle before coating;

(ii) coating the roller compacted material with from 1 to 40 wt % of water soluble inorganic salts in the form of an aqueous solution; and,

(iii) removing water from the product of step (ii) by application of a aeration process selected from: a fluidized bed; and, a drum.

2. A process for the preparation of a coated detergent particle according to claim 1, wherein the surfactant has a hardness from 2 MPa to 20 MPa when compacting.

3. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the inorganic salts act as a builder.

4. A process for the preparation of a coated detergent particle according to claim 3, wherein the inorganic salts comprises sodium carbonate.

5. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the coated detergent particle comprises from 15 to 85 wt % anionic surfactant on surfactant and from 5 to 75 wt % non-ionic surfactant on surfactant that are roller compacted.

6. A process for the preparation of a coated detergent particle according to any one of claims 1 to 7, wherein the coated detergent particle comprises 15 to 100 wt % anionic surfactant on surfactant of which 20 to 30 wt % is sodium lauryl ether sulphate that are roller compacted.

7. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the anionic surfactant is selected from alkyl benzene sulphonates; alkyl ether sulphates; alkyl sulphates.

8. A process for the preparation of a coated detergent particle according to claim 7, wherein the anionic surfactant is selected from sodium lauryl ether sulfate with 1 to 3 ethoxy groups, sodium C₁₀ to C₁₅ alkyl benzene sulphonates and sodium C₁₂ to C₁₈ alkyl sulphates.

9. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the non-anionic surfactant is 10 to 50 EO.

10. A process for the preparation of a coated detergent particle according to claim 9, wherein the non-ionic surfactant is the condensation products of aliphatic C₈ to C₁₈ primary or secondary linear or branched alcohols with 20 to 35 ethylene oxide groups.

11. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the coated detergent particle comprises 20 to 40 wt % of inorganic builder salts as a coating.

12. A process for the preparation of a coated detergent particle according to claim 11, wherein the coated detergent particle comprises 25 to 35 wt % of inorganic builder salts as a coating.

13. A process for the preparation of a coated detergent particle according to any one of the preceding claims, wherein the particle comprises from 0 to 15 wt % water.

14. A process for the preparation of a coated detergent particle according to claim 13, wherein the particle comprises from 1 to 5 wt % water.