STABILIZED PARTICULATE COMPOSITION

Abstract: Particles containing enzyme or optical brightener in a mixture with particles containing peroxy bleach, surfactant or builder are stabilized during storage by coating the former and/or the latter particles with clay, e.g. bentonite.

Description: STABILIZED PARTICULATE COMPOSITION TECHNICAL FIELD The invention relates to a particulate composition comprising: (1) particles containing an enzyme or an optical brightener mixed with (2) separate particles containing a bleaching agent of the peroxy type, a surfactant or a detergent builder. More specifically, the invention relates to such a composition with improved stability during storage of component (1) . The invention also relates to particles of an enzyme or an optical brightener for use in said composition and to a method of producing said composition or particles. BACKGROUND ART Particulate detergents containing particles of an enzyme and/or an optical brightener (O.B.) mixed with separate particles of a bleaching agent, a surfactant or a detergent builder are commonly used. It is known that the latter components may negatively affect the storage stability of the enzyme or O.B. As a solution to this stability problem, the prior art suggests coating of the particles of the enzyme or O.B. It is known that the coating material needs to be carefully selected since it must on one hand protect the enzyme or O.B. and on the other hand release the component rapidly when the detergent is dissolved. As an example, WO 87/07292 (Novo) teaches that the use of an enteric coating on enzyme particles improves the stability in detergent with bleach; the enteric coating material dissolves at the pH of the detergent solution. However, we have found that this does not always give sufficient storage stability. Thus, we have recognized that a need exists for a composition wherein the enzyme or O.B. has improved stability during storage. STATEMENT OF THE INVENTION We have surprisingly found that an enzyme or O.B. in a particulate composition can be stabilized in the above-mentioned mixed composition by applying a clay coating to one or both components. Clay coating has previously been applied to other components, e.g. bleach activator (EP 51,987), but the use of this coating to the components considered here is novel. Accordingly, the invention provides a particulate composition comprising: (1) particles containing an enzyme or an optical brightener mixed with (2) separate particles containing a bleaching agent of the peroxy type, a surfactant or a detergent builder, the composition being characterized in that the particles of the first and/or the second component have a coating containing clay. The invention also provides a particulate product comprising an enzyme or an optical brightener for use in the above composition, characterized by having a coating containing clay. The invention further provides a method for pro¬ ducing said composition or said particulate product, wherein the particles to be coated and an aqueous dis¬ persion of the coating agent are introduced into a fluid bed drying apparatus, whereafter the material leaving the apparatus is collected as the product. Finally, the invention provides a method for producing said composition or said particulate product, comprising introducing the particles to be coated and the coating agent together with water and a binder into a mixer, followed by drying. DETAILED EXPLANATION OF THE INVENTION Typical examples of particulate compositions according to the invention are cleaning compositions, such as detergents and laundry bleaches. The composition of the invention contains separate particles of component (1) and (2) as defined above. The latter tend to destabilize the former during storage. According to the invention, one or both is/are coated with clay. The particulate composition of the invention may obviously contain more than one type of particles of component (1) and/or component (2) , in which case one or more may be coated according to the invention. Component (1) Component (1) is an optical brightener (O.B.) or an enzyme, both of which are commonly used in detergents. The optical brightener used in the invention may be any fluorescent dye capable of increasing the proportion of light reflected from fabric at visible wave lengths, such as those commonly used in laundry detergents. Detergent enzymes are generally icrobial, e.g. proteases, amylases, cellulases and lipases. Typical examples of detergent enzymes are: proteases derived from Bacillus (e.g. from B. licheniformis, from alkalophilic strains according to US 3,723,250 or subtilisin Novo) or Fusarium (e.g. F. oxysporu ) ; a ylase derived from Bacil¬ lus, especially B. amyloliσuefaciens (B. subtilis) or B. licheniformis; cellulase derived from Hu icola. especially H. insolens; lipase derived from Pseudomonas (e.g. Ps. cepacia or Ps. stutzeri) , Humicola (e.g. H. insolens) or Fusarium (e.g. F. oxysporum) . Examples of commercial detergent enzymes are: Alcalase, Savinase, Esperase, BAN, Termamyl, Celluzyme and Lipolase (all trade names of Novo Industri A/S) . Compositions of the invention typically contain 0.005-5%, e.g. 0.01-2% and especially 0.1-1.5% by weight of particles containing component (1). Component (2) Component (2) is a bleaching agent of the peroxy type, a surfactant or a detergent builder. Typical bleaching agents of the peroxy type are organic and inorganic peracids and salts thereof, e.g sodium perborate, sodium percarbonate, potassium persul- phate, magnesium peroxy phthalate and diperoxy dodecane dioic acid. Surfactants may be of the non-ionic, zwitterionic, anionic and cationic types. Especially anionic and more especially cationic surfactants tend to destabilize many enzymes. Typical anionics are linear alkylbenzene sul- phonate (LAS) , alpha olefin sulphonate (AOS) , alkylether betaine and alkyl sulfa betaine. Typical detergent builders are sodium or potassium salts of tripolyphosphoric acid, citric acid, zeolite, ethylenediamine tetraacetic acid (EDTA) , diethylene triamine pentaacetic acid (DTPA) , and nitrilo triacetic acid (NTA) . The particles containing component (2) will typi¬ cally be present in amounts above 0.5%, e.g. above 1% and especially above 2% by weight. The amount of component (2) may be more than 50%, and even more than 80%, e.g. in laundry bleaches. Coating material The clay used in the coating is preferably a layered clay of the smectite type, such as mont orillonite or bentonite. Examples of commercially available bentonite products are ASB, e.g. ASB 350 Powder and ASB 350S Powder (ECC International Ltd., St. Austell, Cornwall, England). The coating material used in the invention may consist essentially of clay, or it may comprise binders, colouring agents (such as Ti0 2 ) , etc. Conventional binders may be used, e.g. polyvinyl pyrrolidone, polyvinyl alcohol, cellulose derivatives (such as hydroxypropyl-, carboxymethyl- or methyl-cellulose) or carbohydrates (such as dextrin, starch hydrolysates, mono- and di-saccharides and sugar alcohols) . If a binder is used, the amount will typically be in the range 1-30% of the coating material. To obtain the stabilization that forms the object of the invention, the amount of coating material should generally be above 0.1%, preferably above 0.5% and most preferably above 2% by weight of the coated particles. The clay types used in the invention may be useful detergent ingredients in their own right, acting as antiredeposition agents. To obtain this effect, it is generally preferred that the amount of clay makes up 0.1- 20% of the total weight of the composition of the inven¬ tion. For increased protection against a bleaching agent, the clay coating applied to the enzyme or O.B. according to the invention may additionally comprise an antioxidant. The antioxidant may be a thiosulphate, a sulphite, a bisulphite, ascorbic acid or an ascorbate, the salts being preferably sodium or ammonium salts. For increased stabilization, the enzyme or O.B. may have an additional protective coating, e.g. consisting of or containing a low-melting wax (such as polyethylene- glycol) , enteric coating according to WO 87/02979, a mono- or diglyceride or a sorbitan ester. This additional coating and the clay coating may both be applied to the same particles of enzyme or O.B., with either coating as the top coating. Alternatively, the additional coating may be applied to the enzyme or O.B. and the clay coating to component (2) . Particle form The particles to be coated according to the inven¬ tion are preferably granulated. Granulation may be done according to methods known in the art, e.g. NL-C 167,993 (Novo), US 4,106,991 (Novo) or US 4,661,452 (Novo). The particle size is preferably such that at least 90% lie in the range 3-2000 μm. For a granulate, at least 90% will usually lie in the range 250-2000 μm (standard granulate) or in the range 100-400 μm (microgranulate) . Coatinσ method The coating according to the invention can be applied by means of any fluid bed method, e.g. a usual fluid bed process, a Wurster bed process or a rotor bed (Glatt) process (vide e.g. David M. Jones, "Factors to consider in fluid-bed processing", Pharmaceutical Techno¬ logy, April 1985) . The fluid bed method can be carried out batch wise or continuously. Alternatively, the coating can be applied by introducing the particles and the coating agent together with water and a binder into a mixer, followed by drying (e.g. fluid-bed drying) . The mixer may be a Lόdige mixer or any type of granulator described in US 4,106,991 at col. 4. Conveniently, the coating agent is introduced as a dry powder, and the binder as an aqueous solution or dispersion. The amount of water should be adjusted so as to avoid agglomeration on one hand, and avoid excessive dust on the other hand. The particles may be introduced first, and the coating agent and binder later, either continuously or intermittently. EXAMPLES EXAMPLE 1 A base (uncoated) granulate of alkaline protease was prepared with the following composition: 22% protease concentrate (SAVINASE (reg. TM of Novo Industri A/S) , prepared according to US 3,723,250 at col. 12, activity 40 KNPU/g) 15% fibrous cellulose (ARBOCEL BC 200) 4% titanium dioxide 10% carbohydrate binder 49% finely ground sodium sulphate The granulate was prepared as described in Example 1 of US 4,106,991, using pure water as granulating agent. After drying, the granulate was sieved, and the fraction between 300 and 900 μm was collected. Part of the above base granulate was coated with bentonite which was sealed to the granulate surface with carbohydrate binder, as follows: 15 kg of the base granu¬ late was introduced into a Lόdige mixer FM 50. 5 kg of bentonite ASB 350 ECC was dosed continuously by the use of a self-regulating loss-in-weight feeding system into the mixer which ran at 95 rpm during the whole layering process. The feeding rate of the bentonite was 50 kg/h. Simultaneously, 0.45 kg of carbohydrate binder as a 25% solution was sprayed to bind the bentonite to the granulate surface using a peristaltic pump and an air atomizing nozzle (atomizing pressure 2 kg/cm 2 /g, pumping rate 300 g/min) . After layering of the bentonite, the wet coated granulate was treated for 1 in. with the granulating device as described in US 4,106,991. The velocity of the mixing device was during this period raised to 180 rpm. The granulate was finally dried to a water content below 1% and sieved to between 300 μm and 1000 μm. Another sample of base granulate was coated as above except that the bentonite was type 35OS, ECC. Part of this granulate was further coated by applying a solution containing 7% of polyethylene glycol and 12.5% of a 1:1 mixture of titanium dioxide and kaolin (SPESWHITE ECC) as described in example 22 of US 4,106,991. For comparison, part of the base granulate was coated with PEG as described above, to represent a prior- art coated granulate. Storage stability tests were carried out by adding granulate to a powder detergent with 25% perborate, storing this at 37 β C and 70% relative humidity, and determining the residual protease activity. Results are expressed in percentage of initial activity. The storage tests were run in 2 series. The results show a marked improvement of storage stability in samples coated according to the invention. The prior-art coating shows no improvement over the uncoated granulate. EXAMPLE 2 A base granulate of alkaline protease was prepared and sieved as in Example 1, except that the following composition was used: 7% protease concentrate (ESPERASE (reg. TM of Novo Industri A/S) , prepared according to US 3,723,250 at col. 12, activity 82 KNPU/g) 10% fibrous cellulose (ARBOCEL BC 200) 4% kaolin SPESWHITE ECC 10% carbohydrate binder 69% finely ground sodium sulphate 15 kg of the base granulate was coated with 5 kg of bentonite ASB 350 and sealed with 0.45 kg of carbohydrate binder in the following manner. The base granulate was introduced into a Lόdige mixer FM 50. The coating/layering was applied with continuous mixing and alternately applying bentonite and binder solution (25% carbohydrate in water) in such a balanced way that the charge was neither too sticky nor contained a substantial amount of free bentonite powder. The actual sequences and amounts of material were: 1. 200 g binder solution 2. 1670 g bentonite 3. 500 g binder solution 4. 1670 g bentonite 5. 500 g binder solution 6. 1670 g bentonite 7. 500 g binder solution 8. 2 min. treatment with granulating device, mixer 180 rpm 9. 150 g binder solution 10. 1 min. treatment with granulating device, mixer 180 rpm The granulate was finally dried to a water content below 1% and sieved to between 300 μm and 1000 μm. Part of the above bentonite-coated granulate was further coated with a water-insoluble sorbitan ester of a fatty acid (FAM0DAN TS, Grindsted Products) as described in Example 1 for PEG. For comparison, part of the base granulate was coated with PEG as in Example 1. Storage stability tests were carried out as in Example 1. Results: The results show that storage stability is sig¬ nificantly improved by use of a bentonite coating according to the invention, and is further improved by combining this with a wax coating. The prior-art coating gives no improved stability. EXAMPLE 3 A base granulate of alkaline protease prepared as in Example 1 was coated with a layer of bentonite ASB 350 and sodium thiosulphate by a conventional fluid-bed process. 350 g of bentonite and 350 g of sodium thiosul¬ phate were dispersed/dissolved in water and sprayed onto 7 kg of base granulate in a Glatt WSG 5 fluid-bed with continuous layering and drying (Air inlet temperature 50 β C, air outlet temperature 35 * C) . The process was completed by a 5 min. drying period with air inlet temper¬ ature 50"C. The granulate was hereafter coated with 5% glyceryl stearate/palmitate (Grindtek MSP 90, Grindsted Products) and 12.5% Ti0 2 :kaolin as described in Example 1 for PEG. Storage tests were made as in Example 1. A prior- art coating (PEG) was included for comparison. Comparison of the above results with Example 1 shows that incorporation of thiosulphate and monoglyceride gives a further improvement of the storage stability obtained with bentonite coating. EXAMPLE 4 Lipase was produced according to EP 305,216 and concentrated by ultrafiltration and evaporation. The resulting liquid lipase concentrate had an activity of 520,000 LU/g (see EP 305,216). The following powder components: 6.0 kg fibrous cellulose ARBOCEL BC200 4.0 kg kaolin SPESWHITE/ECC 4.2 kg carbohydrate binder 24.4 kg finely grounded sodium sulphate were mixed and granulated in a Lόdige FM 130 mixer. 11 kg of the above fluid lipase concentrate was used as the granulating liquid by spraying it on the powder components. Otherwise the granulation process was performed as described in example 1 of US 4,106,991. 15 kg of the base granulate was coated with 5 kg of bentonite (ASB 350) and sealed with 0,45 kg of carbo- hydrate binder in a manner as described in example 3. The granulate was finally dried to a water content below 1% and sieved to between 300 μm and 1000 μm. Storage stability tests were carried out with storage conditions as described in example 1. The bentonite coated lipase granulate showed 2% loss of activity after 4 days storage and 11% loss after 10 days storage. For comparison, the base granulate showed 9% loss of activity after 4 days storage and 23% after 10 days storage.

Claims: CLAIMS 1. A particulate composition comprising: (1) particles containing an enzyme or an optical brightener mixed with (2) separate particles containing a bleaching agent of the peroxy type, a surfactant or a detergent builder, the composition being characterized in that the particles of the first and/or the second component have a coating containing clay. 2. A cleaning composition according to Claim 1, preferably a laundry bleach or a detergent composition. 3. The composition of Claim 1 or 2, wherein component (1) is a microbial enzyme, preferably a protease, an amylase, a lipase or a cellulase. 4. The composition of Claim 1-3, wherein component (2) is a bleaching agent selected from the group of an organic or inorganic peracid or a salt thereof. 5. The composition of Claim 4, wherein the bleaching agent is sodium perborate, sodium percarbonate, potassium persulphate, magnesium peroxy phthalate or diperoxy dodecane dioic acid. 6. The composition of Claim 1-3, wherein component (2) is a surfactant of the anionic type (preferably a linear alkylbenzene sulphonate, an alpha olefin sulphonate, an alcohol ethoxysulphate or a fatty acid soap) or of the zwitterionic, non-ionic or cationic type. 7. The composition of Claim 1-3, wherein component (2) is a detergent builder selected from the group of an alkali metal salt of tripolyphosphoric acid, citric acid, a zeolite, ethylene dia ine tetraacetic acid, diethylene triamine pentaacetic acid or nitrilotriacetic acid. 8. The composition of Claims 1 - 7, wherein the particles of component (1) make up 0.005-5%, preferably 0.01-2% and most preferably 0.1-1.5% of the total weight of the composition. 9. The composition of Claims 1 - 8, wherein the particles of component (2) make up above 0.5%, preferably above 1% and most preferably above 2% of the total weight of the composition. 10. The composition of Claims 1 - 9, wherein said coating material contains above 70% and preferably above 90% of clay. 11. The composition of Claims 1 - 10, wherein the coating further comprises a binder, preferably a car- bohydrate, and preferably in an amount of 1-30% of the weight of the coating. 12. The composition of Claims 1 - 11, wherein the clay is a layered clay, preferably montmorillonite or bentonite. 13. The composition of Claims 1 - 12, wherein the amount of said coating makes up above 0.1%, preferably above 0.5% and most preferably above 2% of the weight of said coated particles. 14. The composition of Claims 1 - 13, wherein the clay contained in said coating makes up 0.1-2% of the weight of the total composition. 15. The composition of Claims 1 - 14, wherein said particles of component (1) additionally have a protective coating, preferably containing or consisting of a wax (with melting point preferably above 35*C) , an enteric substance, a mono- or diglyceride or a sorbitan ester. 16. The composition of Claims 1 - 15, wherein the clay coating is applied to component (1) and this coating also contains a reducing agent, preferably a sulphite or a thiosulphate. 17. The composition of Claims 1 - 16, wherein more than 90% of said coated particles are in the range 2-3000 μm, and more preferably in the range 250-2000 μm. 18. A particulate product comprising an enzyme or an optical brightener for use in the composition of Claim 1- 17, characterized by having a coating containing clay. 19. The particulate product of Claim 18, further characterized as in Claims 3 or 10 - 17. 20. Method for producing the composition of Claims 1- 17 or the particulate product of Claims 18 or 19, wherein the particles to be coated and an aqueous dispersion of the coating agent are introduced into a fluid bed drying apparatus, whereafter the material leaving the apparatus is collected as the product. 21. Method for producing the composition of Claims 1- 17 or the particulate product of Claims 18 or 19, compris- ing introducing the particles to be coated and the coating agent together with water and a binder into a mixer, followed by drying.

Inventors: FALHOLT PER, GOODMAN HOWARD, MARKUSSEN ERIK KJAER, FALHOLT, PER, GOODMAN, HOWARD, MARKUSSEN, ERIK, KJAER
Applicants: NOVO INDUSTRI AS, NOVO INDUSTRI A/S
Application year: 1989
Main classification: C11D3
IPC codes: C11D3, C11D17, C12N9