LIQUID BLEACH COMPOSITION

Abstract: A method for the preparation of a liquid detergent composition comprising an aqueous phase, one or more detergent active materials and a bleach material, said method comprising the in-situ formation of bleach particles having a weight average particle size of more than 20 micrometer.

Description: LIQUID BLEACH COMPOSITION The present invention relates to a liquid detergent composition comprising an aqueous base, detergent active materials and a bleach material. EP 294 904 (P&G) discloses the use of perborate bleach materials in liquid detergent compositions, whereby the bleach materials are present in the form of particles having a weight average particle diameter of from 0.5 to 20 micrometer and whereby said particles being formed by in situ crystallization. A problem in using these small particles is that they require a laborous mixing process, said process often requiring a vigorous mixing step which may lead to moussing of the product. Furthermore these small particles may sometimes be prone to instability due to their relatively large surface area. Also liquid detergent compositions containing these small particles sometimes suffer from high viscosities. EP 368 575 (ICI) relates to suspensions of perborate and thickening agents for incorporation into liquid detergent compositions. A problem in using suspensions of bleach materials for the preparation of liquid detergents is that the presence of an aqueous phase in the suspension leads to the dilution of the detergent composition, especially for concentrated liquid detergent compositions. Such ' a dilution step is often not desirable. Furthermore of pre-suspensions of bleach materials leads to an extra processing and/or transporting step for preparing and/or transporting the suspension, generally this results in a cost increase for the liquid detergent composition. Surprisingly it has now been found that one or more of the above mentioned problems can be solved and stable bleach containing liquid detergent compositions can be obtained by the in-situ formation of bleach particles having a weight average particle size of more than 20 micromete . Accordingly the present invention relates to a method for the preparation of a liquid detergent composition comprising an aqueous phase, one or more detergent active materials and a bleach material, said method comprising the in-situ formation of bleach particles having a weight average particle size of more than 20 micrometer. A further aspect of the invention is that if the bleach particles having a weight average particle size of more than 20 micrometer are formed in situ, this allows the preparation of liquid detergent compositions which comprise relatively low amounts of water (say less than 50 % by weight, more preferably less than 40 % by weight, more preferably from 10 to 35 %) in combination with relatively high amount of detergent active materials (say more than 15 % by weight, more preferably more than 20 %, most preferably from 25 to 60 %) and relatively high amounts of bleach materials (say more than 1 %, more preferred more than 7 %, most preferred from 10 to 50 %) . Accordingly the invention also relates to a liquid detergent composition comprising less than 50 % by weight of water, more than 15 % of detergent active materials and more than 1 % by weight of bleach material, said bleach material having a weight average particle size of more than 20 micrometer. bleach material Compositions according to the present invention comprise a bleach material, which is preferably a peroxygen bleach. This bleach component is present in the system at least partly in undissolved form, but generally at least a minor part of the peroxygen bleach will be εolubilized. The solid particles will generally be suspended in the system. Examples of suitable bleach compounds include the perborates, persulfates, peroxy disulfates, calciumperoxides, perphosphates and the crystalline peroxyhydrates formed by reacting hydrogen peroxide with urea or alkali metal carbonate. Also encapsulated bleaches may be used. Especially preferred is the use of perborate or percarbonate bleaches. Typical amounts of bleach will be between 1 and 50 % by weight of the aqueous composition, more preferred from 7 to 30 %, especially preferred from 10 to 25 % by weight of the composition. The weight average particle size of the bleach particles is more than 20 micrometer, preferably from 22-150 micrometer, more preferably from 25 to 60 micrometer, most preferably from 30 to 50 or 45 micrometer. A suitable method for determining the weight average particle size involves the making of microscopy pictures of the liquid detergent composition at a magnification of between 50 and 600 (preferably about 150) , followed by the manual or automatic counting of the visible particles, measuring the particle diameter for each particle and calculating the weight average particle size for the visible particles. Sometimes the bleach material will be suspended in the system as agglomerates of small elementary bleach particles. Since it is believed that normally the size of the agglomerates rather than the size of the elementary bleach particles determines the characteristics of the final product, for the purpose of the invention, the bleach particle size refers to the weight average particle size of these agglomerates. If agglomerates of bleach particles are present, for determining the particle size, care has to be taken not to subject the measuring sample to unnecessary shear or pressure, because this may lead to the fragmentation of the agglomerates. detergent active materials Compositions of the present invention also comprise detergent active materials. Surprisingly it has been found that physically stable bleach containing liquid detergent compositions can be obtained by the in-situ formation of bleach particles having a weight average particle size of more than 20 micrometer. In the widest definition the detergent active materials in general, may comprise one or more surfactants, and may be selected from anionic, cationic, nonionic, zwitterionic and amphoteric species, and (provided mutually compatible) mixtures thereof. For example, they may be chosen from any of the classes, sub-classes and specific materials described in "Surface Active Agents" Vol. I, by Schwartz & Perry, Interscience 1949 and "Surface Active Agents" Vol. II by Schwartz, Perry & Berch (Interscience 1958) , in the current edition of "McCutcheon's Emulsifiers & Detergents" published by the McCutcheon division of Manufacturing Confectioners Company or in Tensid-Taschenburch", H. Stache, 2nd Edn. , Carl Hanser Verlag, Munchen & Wien, 1981. Suitable nonionic surfactants 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. Specific nonionic detergent compounds are alkyl (Cg-C 18 ) primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. other so-called nonionic detergent compounds include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides. Also possible is the use of salting out resistant active materials, such as for example described in EP 328 177, especially the use of alkyl poly glycoside surfactants, such as for example disclosed in EP 70 074. Suitable anionic surfactants 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 (C 8 -C 18 ) alcohols produced for example from tallow or coconut ^ oil, sodium and potassium alkyl (Cg-C 2 o benzene sulphonates, i particularly sodium linear secondary alkyl (C 10 -C 15 ) benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates; sodium and potassium salts of sulphuric acid esters of higher (C 8 -C 18 ) fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine; alkane monosulphonates such as those derived by reacting alpha- olefins (C3-C20) with sodium bisulphite and those derived from reacting paraffins with S0 2 and Cl 2 and then hydrolysing with a base to produce a random sulponate; and olefin sulphonates, which term is used to describe the material made by reacting olefins, particularly C 10 -C 20 alpha-olefins, with S0 3 and then neutralising and hydrolysing the reaction product. The preferred anionic detergent compounds are sodium (C- j ^- C- j ^) alkyl benzene sulphonates and sodium or potassium primary (C 10 ~ c i 8 ) alkyl sulphates. It is also possible, and sometimes preferred, to include an alkali metal soap of a fatty acid, especially a soap of an acid having from 12 to 18 carbon atoms, for example oleic acid, ricinoleic acid, and fatty acids derived from castor oil, alkylsuccinic acid, rapeseed oil, groundnut oil, coconut oil, palmkernel oil or mixtures thereof. The sodium or potassium soaps of these acids can be used. The total detergent active material may be present at from 15% to 70% by weight of the total composition, for example from 20% to 60% and typically from 30% to 50% by weight. optional ingredients Compositions of the invention may be un-structured (isotropic) but are preferably structured. Structured liquids of the invention may be internally structured whereby the structure is formed by the detergent active materials in the composition or externally structured, 7 whereby the structure is provided by an external structurant. Preferably compositions of the invention are internally structured. Most preferably compositions of the invention comprise a surfactant structure comprising lamellar droplets of detergent active materials. Some of the different kinds of active-structuring which are possible are described in the reference H.A. Barnes, "Detergents", Ch.2. in K. Walters (Ed), "Rheo etry: Industrial Applications*^, J. Wiley & Sons, Letchworth 1980. In general, the degree of ordering of such systems increases with increasing surfactant and/or electrolyte concentrations. At very low concentrations, the surfactant can exist as a molecular solution, or as a solution of spherical micelles, both of these being isotropic. With the addition of further surfactant and/or electrolyte, structured (antisotropic) systems can form. They are referred to respectively, by various terms such as rod-micelles, planar lamellar structures, lamellar droplets ahd liquid crystalline phases. Often, different workers have used different terminology to refer to the structures which are really the same. For instance, in European patent specification EP-A-151 884, lamellar droplets are called "spherulites". The presence and identity of a surfactant structuring system in a liquid may be determined by means known to those skilled in the art for example, optical techniques, various rheometrical measurements, x-ray or neutron diffraction, and sometimes, electron microscopy. When the compositions are of lamellar droplet structure then in many cases it is preferred for the aqueous continuous phase to contain dissolved electrolyte. As used herein, the term electrolyte means any ionic water soluble material. However-, in lamellar dispersions, not all the electrolyte is necessarily dissolved but may be suspended as particles of solid because the total electrolyte concentration of the liquid is higher than the solubility limit of the electrolyte. Mixtures of electrolytes also may be used, with one or more of the electrolytes being in the dissolved aqueous phase and one or more being substantially only in the suspended solid phase. Two or more electrolytes may also be distributed approximately proportionally, between these two phases. In part, this may depend on processing, e.g. the order of addition of components. On the other hand, the term "salts" includes all organic and inorganic materials which may be included, other than surfactants and water, whether or not they are ionic, and this ter encompasses the sub-set of the electrolytes (water soluble materials) . The selection of surfactant types and their proportions, in order to obtain a stable liquid with the required structure will be fully within the capability of those skilled in the art. However, it can be mentioned that an important sub-class of useful compositions is those where the detergent active material comprises blends of different surfactant types. Typical blends useful for fabric washing compositions include those where the primary surfactant(s) comprise nonionic and/or a non- alkoxylated anionic and/or an alkoxylated anionic surfactant. In the case of blends of surfactants, the precise proportions of each component which will result in such stability and viscosity will depend on the type(s) and amount(s) of the electrolytes, as is the case with conventional structured liquids. Preferably though, the compositions contain from 1% to 60%, especially from 10 to 45% of a salting-out electrolyte. Salting-out electrolyte has the meaning ascribed to in specification EP-A-79 646, that is salting-out electrolytes have a lyotropic number of less than 9.5. Optionally, some salting-in electrolyte (as defined in the latter specification) may also be included, provided it is of a kind and in an amount compatible with the other components and the composition is still in accordance with the definition of the invention claimed herein. Some or all of the electrolyte (whether salting-in or salting-out) , or any substantially water insoluble salt which may be present, may have detergency builder properties. In any event, it is preferred that compositions according to the present invention include detergency builder material, some or all of which may be electrolyte. The builder material is any capable of reducing the level of free calcium ions in the wash liquor and will preferably provide the composition with other beneficial properties such as the generation of an alkaline pH, the suspension of soil removed from the fabric and the dispersion of the fabric softening clay material. Preferably the salting-out electrolyte comprises citrate. Examples of phosphorus-containing inorganic detergency builders, when present, include the water-soluble salts, especially alkali metal pyrophosphates, orthophosphates, polyphosphates and phosphonates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, phosphates and hexametaphosphates. Phosphonate sequestrant builders may also be used. Examples of non-phosphorus-containing inorganic detergency builders, when present, include water- soluble alkali metal carbonates, bicarbonates, silicates and crystalline and amorphous aluminosilicates. Specific examples include sodium carbonate (with or without calcite seeds) , potassium carbonate, sodium and potassium bicarbonates, silicates and zeolites. Examples of organic detergency builders, when present, include the alkaline metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl carboxylates and polyhydroxysulphonates. Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilitriacetic acid, oxydisuccinic acid, CMOS, TMS, TDS, melitic acid, benzene polycarboxylic acids and citric acid. Preferably the level of non-soap builder material is from 0-50% by weight of the composition, more preferred from 5-40%, most preferred 10-35%. In the context of organic builders, it is also desirable to incorporate polymers which are only partly dissolved, in the aqueous continuous phase as described in EP 301.882. This allows a viscosity reduction (due to the polymer which is dissolved) whilst incorporating a sufficiently high amount to achieve a secondary benefit, especially building, because the part which is not dissolved does not bring about the instability that would occur if substantially all were dissolved. Typical amounts are from 0.5 to 4.5% by weight. It is further possible to include in the compositions of the present invention, alternatively, or in addition to the partly dissolved polymer, yet another polymer which is substantially totally soluble in the aqueous phase and has an electrolyte resistance of more than 5 grams sodium nitrilotriacetate in 100ml of a 5% by weight aqueous solution of the polymer, said second polymer also having a vapour pressure in 20% aqueous solution, equal to or less than the vapour pressure of a reference 2% by weight or greater aqueous solution of polyethylene glycol having an average molecular weight of 6000; said second polymer having a molecular weight of at least 1000. Use of such polymers is generally described in our EP 301,883. Typical levels are from 0.5 to 4.5% by weight. The viscosity of compositions according to the present is preferably less than 2,500 mPa.s, more preferred less than 2,000 mPa.s, most preferred less than 1,500 mPa.s, especially preferred between 30 and 900 mPa.s at 21 s" 1 . One way of regulating the viscosity and stability of compositions according to the present invention is to include viscosity regulating polymeric materials. Viscosity and/or stability regulating polymers which are preferred for incorporation in compositions according to the invention include deflocculating polymers having a hydrophilic backbone and at least one hydrophobic side chain. Such polymers are for instance described in our copending European application EP 89201530.6 (EP 346 995). Preferably the amount of viscosity regulating polymer is from 0.1 to 5% by weight of the total composition, more preferred from 0.2 to 2%. Compositions of the invention may also comprise materials for adjusting the pH. For lowering the pH it is preferred to use weak acids, especially the use of organic acids is preferred, more preferred is the use of C 1-8 carboxylic acids, most preferred, is the use of citric acid. The use of these pH lowering agents is especially preferred when the compositions of the invention contain enzymes such as amylases, proteases and lipolases. Apart from the ingredients already mentioned, a number of optional ingredients may also be present, for example lather boosters such as alkanola ides, particularly the monoethanolamides derived from palm kernel fatty acids and coconut fatty acids, fabric softeners such as clays, amines and amine oxides, lather depressants, inorganic salts such as sodium sulphate, and, usually present in very minor amounts, fluorescent agents, perfumes, germicides colourants and enzymes such as proteases, cellulases, amylases and lipases (including Lipolase (Trade Mark) ex Novo) . Suitable examples of protease enzymes are Savinase (ex Novo) , Maxatal (gist-brocades) , Opticlean (ex MKC) or AP122 (ex Showa Denko) , Alcalase, Maxatase, Esperase, Optimase, proteinase K and subtilisin BPN. Suitable lipolases are for example Lipolase (ex Novo) , Amano lipases, Meito lipases, Lipozym, SP 225, SP 285, Toyo Jozo lipase. Suitable amylases are for example Termamyl (TM of Novo) and Maxamyl. Suitable cellulases include Celluzym (ex Novo) . Compositions of the invention preferably comprise from 5 -50 % by weight of water, more preferably from 10- 45%, most preferably from 15-35 %. Liquid detergent compositions according to the invention are preferably physically stable in that they show less than 2% by volume phase separation upon storage for 21 days after preparation at 25 β C. Liquid detergent compositions according to the invention are preferably volume stable in that they show less than 25% preferably less than 10%, more preferably less than 5% volume increase during storage at a temperature between 20 and 37°C for a period of three months after preparation. Also preferably compositions according to the invention have solid suspending properties, most preferably they do not yield any visible sedimentation after storage for three weeks at 21 oC . Compositions of the present invention may comprise one or more bleach precursor agents. A well-known example of such an agent is TAED. Preferably the bleach precursor agent is present in the system in at least partly undissolved form. One way of ensuring that the precursor is present in undissolved form is to increase the amount of electrolyte in the composition, therewith reducing the solubility of the precursor in the system. Suitable electrolytes for this purpose are for instance the at least partially water soluble carbonate, sulphate and halogenide salts. Compositions of the invention may also advantageously comprise one or more ingredients for the stabilization of bleach materials, suitable materials are for example metaborate electrolytes «ιnd magnesium salts. In use the detergent compositions of the. invention will be diluted with wash water to form a wash liquor for instance for use in a washing machine. The concentration of liquid detergent composition in the wash liquor is preferably from 0.05 to 10 %, more preferred from 0.1 to 3% by weight. To ensure effective detergency, the liquid detergent compositions preferably*are alkaline, and it is preferred that they should prov de * a pH within the range of about 7.0 to 12, preferably about 8 to about 11, when used in aqueous solutions of the composition at the recommended concentration. To meet this requirement, the undiluted liquid composition should preferably be of a pH above 7, for example about pH 8.0 to about 12.5. It should be noted that an excessively high pH, e.g. over about pH 13, is less desirable for domestic safety. One aspect of the invention is a process for the preparation of liquid bleach containing compositions, said process involving the in-situ formation of bleach particles having a weight average particle size of more than 20 micrometer. The in-situ formation of bleach particles relates to processes whereby the bleach particles such as present in the final composition, have been formed in-situ, for example by a dissolution/ recrystallization process or the hydration of perborate monohydrate. It is believed to be well within the ability of the skilled person to adapt the processing conditions such that the required particle sizes are obtained. Preferred parameters to be varied for obtaining the desired particles sizes are physical form of the bleach materials that are added to the composition, stirring conditions and order of addition. When the bleach material is a perborate bleach material, preferably the bleach is added as perboratemonohydrate, which will be formed into perborate tetrahydrate in the composition. Another preferred method of bleach incorporation is the use of a combination of hydrogen peroxide and a borate material, which will in-situ react to form a perborate bleach. A preferred borate material is metaborate. It is preferred that the bleach materials are added into the composition under mild stirring conditions, preferably less than 10 c/s, more preferably less than 5 c/s, most preferably from 0.2 to 3 c/s. The tip-speed of the stirrer is preferably 0.01-10 m/s, more preferably 0.1 to 5 m/s, most preferred 0.5 to 2 m/s. A preferred order of addition involves the addition of electrolyte non-bleach materials to water of elevated temperature, followed by the addition of detergent active materials, the bleach material and the remaining ingredients. The invention will now be illustrated by way of the following Examples. In all Examples, unless stated to the contrary, all percentages are by weight. 15 Example I The following composition can be prepared by adding the citrate/citric acid and the polymer to water at elevated temperature, followed by addition of the detergent active materials as a pre ix and the bleach material. t • * ■ - ) mixture used to adjust pH to 8.5 2 ) polymer A-ll as described in EP 346 995 The composition can be prepared several times on a 1 kg scale in a 2 litre glass with a 6 blade stirrer having a diameter of 8 cm, while the type of bleach and the stirring conditions are varied as follows: 3 ) ratios chosen such that perborate tetrahydrate is formed in-situ. Each of the compositions can be stored for 24 hours at ambient temperature and microscopy pictures can be taken at a magnification of 150 times. The weight average particle size of the bleach materials is determined by counting the visible particles. The physical stability, the volume stability and the solid suspending properties of the composition are determined. Example II The following compositions were made by adding the citric acid/citrate to water, followed by the addition of the sodium metaborate, sodium hydroxide for neutralising the detergent active materials, the polymer, a premix of the detergent active materials in acid form the minor ingredients and the hydrogen peroxide or the perborate monohydrate. INGREDIENT fwt parts) A B Notes: - Na-Dobs is sodium dodecylbenzene sulfonate (Marlon AS3 neutralized with NaOH) . - Synperonic A7 is a C 13 „ 15 fatty alcohol with on average 7 EO groups per molecule ex ICI. - A mixture of citrate/citric acid is used to obtain a final pH of the product of 9. - Metaborate/H 2 0 2 refers to sodium metaborate and H 2 0 2 in ratios such that 15 parts of perborate tetrahydrate can be formed in situ. - The polymer is a deflocculating polymer as described in EP 346 995 as polymer A-44. - The 2.6 parts sodium metaborate are added in addition to the metaborate used for the formation of perborate. Each of the formulation was prepared on a 1 kg scale in a 2 litre glass with a 6 blade stirrer having a diameter of 8 cm. The stirring conditions were varied as indicated below. The particle size of the bleach was determined by applying a thin film of the product under moderate pressure onto a microscopy glass plate followed by the making of a microscopy picture at a magnification of about 400, whereafter the weight average particle size was -roughly- determined by counting the course fraction of the visible particles and measuring their particle size. In most of the samples the bleach was present in the form of agglomerates consisting of small elementary bleach particles. In the table below the average particle sizes of the agglomerates is given. The following table indicates the weight average particle size in micron of the bleach in the formulation as a function of stirring rate.: COMPOSITION/RATE OF STIRRING 10 C/s 5 C/s 2 C/S A B C D Example III The following compositions were prepared by adding the electrolyte together with the minor ingredients except for the perfume and the enzymes to water of elevated temperature, followed by the addition of the detergent active material as a premix under stirring and thereafter cooling the mixture and adding the enzymes, perfumes and the bleach. INGREDIENT (% WT) A B Na-Dobs 23.3 21 Synperonic A7 10 9 Glycerol 3.9 Metaborate 2.9 2.6 Nacitrate/Citric acid 1 ) 11.1 9.8 Dequest 2060S (as 100%) 0.4 0.4 Na-perborate monohydrate 7.2 10 Enzyme, Alcalase 0.8 0.8 CaCl 2 .2H 2 0 0.2 0.2 Fluorescer, Tinopal CBSX 0.1 0.1 Silicon, Dow Corning DB100 0.3 0.3 Perfume 0.3 0.3 Deflocculating polymer ) 1.1 1 Water balance pH 9 9 ■■■ -) This mixture is used to adjust the final pH. 2) Expressed as % of analyzed enzyme level in the fresh sample. 3) Deflocculating polymer of formula I of EP 346995 wherein X=50, Y=0, R 5 =H, R * * * -= -CO-O, R 2 and R 3 are absent, R = -C 12 H 25 , MW=7,500. 4 ) wt% -approximate- of total perborate, obtained by removal of the undissolved bleach particles by mild centrifugation. 5) not measured The obtained product had the following characteristics: A B Volume stability (% volume 0 0 increase, 3 months 25°C) clear layer separation no no (3 weeks 37 β C) solid sedimentation no no (3 weeks 37°C) Viscosity 21 s _1 800 760 Dissolved perborates 5 ) 8 6 Bleach activity 96 97 (2 months ambient T) enzyme activity 76 n.m. 5) (2 months ambient T) 2 )

Claims: Claims 1. A method for the preparation of a liquid detergent composition comprising an aqueous phase, one or more detergent active materials and a bleach material, said method comprising the in-situ formation of bleach particles having a weight average particle size of more than 20 micrometer. 2. A method according to claim 1, wherein the bleach material is a perborate bleach which is preferably added to the composition as perborate monohydrate. 3. A method according to claim 1, wherein the bleach material is a perborate bleach which is preferably formed in situ by a reaction of hydrogen peroxide and a borate material. 4. A method according to claim 1,2 or 3, involving the mixing of the bleach into the composition at a stirring rate of less than 10 c/s 5. A liquid detergent composition comprising less than 50 % by weight of water, more than 15 % of detergent active materials and more than 1 % by weight of bleach material, said bleach material having a weight average particle size of more than 20 micrometer. 6. A liquid detergent composition according to claim 5, comprising a surfactant structure comprising lamellar droplets of detergent active material. 7. A liquid detergent composition according to claim 5 or 6, having a viscosity of less than 2,500 mPas at 21 s _1 , having a pH of 7.0 to 12.0 and being physically stable, volume stable and having solid suspending properties.

Inventors: OLSTHOORN THERESIA MARIA, VAN DE PAS JOHANNES CORNELIS, OLSTHOORN, THERESIA, MARIA, VAN DE PAS, JOHANNES, CORNELIS
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1991
Main classification: C11D3
IPC codes: C11D3, C11D17, D06L3