Stabilized, bleach containing, liquid detergent compositions

Abstract: Aqueous, bleach containing, liquid detergent compositions, which are stabilized against bleach decomposition due to contamination by metal traces are disclosed. The stabilizing effect is obtained by using hydroxy ethylidene-1,1 diphosphonic acid in the composition.

Description: Technical field The present invention relates to aqueous liquid detergent compositions containing solid, water-soluble peroxygen compounds. The peroxygen compounds are stabilized, even when the detergent composition is contaminated with metals like iron and manganese. Background Liquid detergent compositions containing peroxygen compounds have recently become available; for instance, EP 0 294 904 discloses aqueous liquid detergent compositions which contain perborate compounds. Phosphonates, their sequestration properties and their use in granular bleach containing detergent are well known in the Art, and have been described in various publications and patents, for instance EP 0 141 200, EP 0 175 315, DE 3 444 678 A₁. In a publication entitled : "Phosphonates : multifunctional ingredients for laundry detergents". By H.B. MAY, H. Nijs and V. GODECHARLES in "Happi" March 1986 the use of phosphonates in granular detergent in order to stabilize peroxygen compounds during the wash cycle is disclosed. It is an object of the present invention to provide liquid detergent compositions containing solid, water-soluble peroxygen compounds which are prevented from decomposition due to metal contamination. Summary of the invention This invention provides liquid detergent compositions having a pH at room temperature of at least 8.5, which contain an organic surface active agent solid, water-soluble peroxygen compounds and which further contain, as a peroxygen stabilizer against metal contamination, from 0.01% to 5% by weight preferably from 0.05% to 1% by weight of hydroxy-ethylidene-1,1-diphosphonic acid (HEDP). Detailed description It is only recently that it has become possible to formulate liquid detergent compositions containing peroxygen bleaches. Under normal circumstances, the chemical stability of the peroxygen compound in such liquid detergents is satisfying, thus providing the product with good storage stability characteristics. However, some products have shown a certain instability of the peroxygen compound, which creates a problem in terms of a sufficient storage stability for an adequate shelf life of these products. The cause for this peroxygen instability has now been identified as a contamination of the product by heavy metals which catalyze the decomposition of the peroxygen compound in the composition. The contamination of the product by metal traces is an important problem in normal industrial practice; indeed it has been discovered that some of the raw materials used for the manufacture of the product, are themselves carrying transition metals, at trace levels. Further, while manufacturing, shipping, handling or stocking the product, accidental contamination may occur because of corroded pipes or containers. It is thus an object of the present invention to provide liquid detergent compositions, containing bleaches, which are stable upon manufacture and storage, even when metal traces have contaminated the product. It is well known that phosphonates are amongst the best peroxygen stabilizers and, accordingly, several phosphonates were tested, including hexamethylene diamine tetra (methylene phosphonic acid) [HMTMPA] and diethylene triamine penta (methylene phosphonic acid) [DETMPA]. Unfortunately these compounds did no provide the expected protection to peroxygen compounds against metal traces. It has now surprisingly been found that hydroxy-ethylidene 1,1-diphosphonic acid (HEDP), when added in an amount ranging from 0.01% to 5% by weight, has the required stabilizing effect on peroxygen compounds in liquid detergent compositions which are contaminated with metal traces. This is unexpected, since the stability constants of the complexes of HEDP with most transition metals are lower than those of HMTMPA or DETMPA (MONSANTO technical bulletin 53-39(E) ME.2 (1983)), and also because HEDP has been described as having no stabilizing effect on peroxygen compounds (H.B. May, H. Nijs, V. Godecharles in Happi, March 1986). The term hydroxy-ethylidene-1,1-diphosphonic acid (HEDP) as used herein, refers to any form of the compound, regardless of the pH of the composition; further, all percentages by weight of HEDP stated throughout this specification are based on the molecular weight of the acid form. The preferred amount of HEDP in the present invention's compositions is from 0.05% to 1% by weight, most preferably 0.25%. HEDP is a commercially available compound, for instance Monsanto's DEQUEST 2010 (R) is suitable for the present invention. Further, the liquid detergent compositions herein all contain from 5 % to 60 % by weight of the liquid detergent composition, preferably from 15 % to 40 % of an organic surface-active agent selected from nonionic, anionic, cationic, and zwitterionic surface-active agents and mixtures thereof. Synthetic anionic surfactants can be represented by the general formula R₁SO₃M wherein R₁ represents a hydrocarbon group selected from the group consisting of straight or branched alkyl radicals containing from about 8 to about 24 carbon atoms and all phenyl radicals containing from about 9 to about 15 carbon atoms in the alkyl group. M is a salt-forming cation which is typically selected from the group consisting of sodium, potassium, ammonium, and mixtures thereof. A preferred synthetic anionic surfactant is a watersoluble salt of an alkylbenzene sulfonic acid containing from 9 to 15 carbon atoms in the alkyl group. Another preferred synthetic anionic surfactant is a water-soluble salt of an alkyl sulfate or an alkyl polyethoxylate ether sulfate wherein the alkyl group contains from about 8 to about 24, preferably from about 10 to about 18 carbon atoms and there are from about 1 to about 20, preferably from 1 to about 12 ethoxy groups. Other suitable anionic surfactants are disclosed in U.S. Patent 4,170,565, Flesher et al., issued October 9, 1979. The nonionic surfactants are conventionally produced by condensing ethylene oxide with a hydrocarbon having a reactive hydrogen atom, e.g. a hydroxyl, carboxyl, or amino group, in the presence of an acidic of basic catalyst, and include compounds having the general formula RA(CH₂CH₂0) n H wherein R represents the hydrophobic moiety, A represents the group carrying the reactive hydrogen atom and n represents the average number of ethylene oxide moieties. R typically contains from about 8 to 22 carbon atoms. They can also be formed by the condensation of propylene oxide or copolymers of ethylene oxide and propylene oxide with a lower molecular weight compound. n usually varies from about 2 to about 24. The hydrophobic moiety of the nonionic compound is preferably a primary or secondary, straight or branched, aliphatic alcohol having from about 8 to 24, preferably from about 12 to about 20 carbon atoms. A more complete disclosure of suitable nonionic surfactants can be found in U.S. Patent 4,111,855. Mixtures of nonionic surfactants can be desirable. Suitable cationic surfactants include quaternary ammonium compounds of the formula R₁R₂R₃R₄N⁺ where R₁, R₂, and R₃ are methyl groups and R₄ is a C₁₂-C₁₅ alkyl group, or where R₁ is an ethyl or hydroxy ethyl group, R₂ and R₃ are methyl groups and R₄ is a C₁₂-C₁₅ alkyl group. Zwitterionic surfactants include derivatives of aliphatic quaternary ammonium, phosphonium, and sulphonium compounds in which the aliphatic moiety can be a straight or branched chain and wherein one of the aliphatic substituents contains from about 8 to about 24 carbon atoms and another substituent contains, at least, an anionic water-solubilizing group. Particularly preferred zwitterionic materials are the ethoxylated ammonium sulfonates and sulfates disclosed in U.S. Patents 3,925,262, Laughlin et al., issued December 9, 1975 and 3,929,678, Laughlin et al., issued December 30, 1975. Semi-polar nonionic surfactants include water-soluble amine oxides containing one alkyl or hydroxy alkyl moiety of from about 8 to about 28 carbon atoms and two moieties selected from the group consisting of alkyl groups and hydroxy alkyl groups, containing from 1 to about 3 carbon atoms which can optionally be joined into ring structures. Suitable anionic synthetic surface-active salts are selected from the group of sulfonates and sulfates.The like anionic detergents are well-known in the detergent arts and have found wide-spread application in commercial detergents. Preferred anionic synthetic water-soluble sulfonate of sulfate salts have in their molecular structure an alkyl radical containing from about 8 to about 22 carbon atoms. Examples of such preferred anionic surfactant salts are the reaction products obtained by sulfating C₈-C₁₈ fatty alcohols derived from tallow and coconut oil; alkylbenzene sulfonates wherein the alkyl group contains from about 9 to 15 carbon atoms; sodium alkylglyceryl ether sulfonates; ether sulfates of fatty alcohols derived from tallow and coconut oils; coconut fatty acid monoglyceride sulfates and sulfonates; and water-soluble salts of paraffin sulfonates having from about 8 to about 22 carbon atoms in the alkyl chain. Sulfonated olefin surfactants as more fully described in e.g. U.S. Patent Specification 3,332,880 can also be used. The neutralizing cation for the anionic synthetic sulfonates and/or sulfates is represented by conventional cations which are widely used in detergent technology such as sodium and potassium. A particularly preferred anionic synthetic surfactant component herein is represented by the water-soluble salts of an alkylbenzene sulfonic acid, preferably sodium alkylbenzene sulfonates having from about 10 to 13 carbon atoms in the alkyl group. A preferred class of nonionic ethoxylates is represented by the condensation product of a fatty alcohol having from 12 to 15 carbon atoms and from about 2 to 10, preferably 3 to 7 moles of ethylene oxide per mole of fatty alcohol. Suitable species of this class of ethoxylates include : the condensation product of C₁₂-C₁₅ oxo-alcohols and 7 moles of ethylene oxide per mole of alcohol; the condensation product of narrow cut C₁₄-C₁₅ oxo-alcohols and 7 or 9 moles of ethylene oxide per mole of fatty(oxo)alcohol; the condensation product of a narrow cut C₁₂-C₁₃ fatty(oxo)alcohol and 6,5 moles of ethylene oxide per mole of fatty alcohol; and the condensation products of a C₁₀-C₁₄ coconut fatty alcohol with a degree of ethoxylation (moles EO/mole fatty alcohol) in the range from 5 to 8. The fatty oxo alcohols while mainly linear can have, depending upon the processing conditions and raw material olefins, a certain degree of branching, particularly short chain such as methyl branching. A degree of branching in the range from 15 % to 50 % (weight%) is frequently found in commercial oxo alcohols. Preferred nonionic ethoxylated components can also be represented by a mixture of 2 separately ethoxylated nonionic surfactants having a different degree of ethoxylation. For example, the nonionic ethoxylate surfactant containing from 3 to 7 moles of ethylene oxide per mole of hydrophobic moiety and a second ethoxylated species having from 8 to 14 moles of ethylene oxide per mole of hydrophobic moiety. A preferred nonionic ethoxylated mixture contains a lower ethoxylate which is the condensation product of a C₁₂-C₁₅ oxo-alcohol, with up to 50 % (wt) branching, and from about 3 to 7 moles of ethylene oxide per mole of fatty oxo-alcohol, and a higher ethoxylate which is the condensation product of a C₁₆-C₁₉ oxo-alcohol with more than 50 % (wt) branching and from about 8 to 14 moles of ethylene oxide per mole of branched oxo-alcohol. Suitable bleaches in the present compositions are solid, water-soluble peroxygen compounds. Preferred compounds include perborates, persulfates, peroxydisulfates, perphosphates and the crystalline peroxyhydrates formed by reacting hydrogen peroxyde with sodium carbonate or urea. Preferred peroxygen bleach compounds are sodium perborate monohydrate and sodium perborate tetrahydrate, as well as sodium percarbonate. Perborate bleaches in the present composition can be in the form of small particles i.e. having a diameter of from 0,1 to 20 micrometers, said particles having been formed by in situ crystallization of the perborate. The term "in situ crystallization" relates to processes whereby perborate particles are formed from larger particles or from solution, in the presence of the water/anionic surfactant/detergent builder matrix. This term therefore encompasses processes involving chemical reactions, as when sodium perborate is formed by reacting stoichiometric amounts of hydrogen peroxide and sodium metaborate or borax. It also encompasses processes involving dissolution and recrystallization, as in the dissolution of perborate monohydrate and subsequent formation of perborate tetrahydrate. Recrystallization may also take place by allowing perborate monohydrate to take up crystal water, whereby the monohydrate directly recrystallizes into the tetrahydrate, without dissolution step. In one embodiment of the invention, a perborate compound, e.g., sodium perborate monohydrate, is added to an aqueous liquid comprising the anionic surfactant and the detergent builder. The resulting slurry is stirred. During this stirring the perborate compound undergoes a process of dissolution/recrystallization. Due to the presence of the anionic surfactant and the detergent builder this dissolution/recrystallization process results in particles having the desired particle diameter. As the monohydrate is more susceptible to recrystallization, the monohydrate is preferred for this embodiment of the invention. For reasons of physical stability it is preferred that the particle size distribution is relatively narrow; i.e., it is preferred that less than 10 % (wt) has a particle diameter greater than 10 micrometers. In a second embodiment of the invention the perborate compound is formed in situ by chemical reaction. For example, sodium metaborate is added to an aqueous liquid comprising the anionic surfactant and the detergent builder. Then a stoichiometric amount of hydrogen peroxide is added while stirring. Stirring is continued until the reaction is complete. Instead of metaborate, other borate compounds, including e.g., borax and boric acid can be used. If borax is used as the boron compound, a stoichiometric amount of a base, e.g. sodium hydroxide, is added to ensure reaction of the borax to metaborate. The process then proceeds as described hereinabove for metaborate conversion. Instead of hydrogen peroxide, other peroxides may be used (e.g., sodium peroxide), as known in the art. Preferred liquid detergent compositions contain, in addition to water, a water-miscible organic solvent. The solvent reduces the solubility of perborate in the liquid phase and thereby enhances the chemical stability of the composition. It is not necessary that the organic solvent be fully miscible with water, provided that enough of the solvent mixes with the water of the composition to affect the solubility of the perborate compound in the liquid phase. The water-miscible organic solvent must, of course be compatible with the perborate compound at the pH that is used. Therefore, polyalcohols having vicinal hydroxy groups (e.g. 1,2-propanediol and glycerol) are less desirable. Examples of suitable water-miscible organic solvents include the lower aliphatic monoalcohols, and ethers of diethylene glycol and lower monoaliphatic monoalcohols. Preferred solvents are ethanol, iso-propanol, 1-methoxy, 2-propanol, ethyldiglycolether and butyldiglycolether. The compositions according to the invention may also contain detergent enzymes; suitable enzymes include the detergent proteases, amylases, lipases, cellulases and mixtures thereof. Preferred enzymes are high alkaline proteases e.g. Maxacal (R) and Savinase (R). Silicone-coated enzymes, as described in EP-A-0238216 can also be used. Preferred compositions herein optionally contain as a builder a fatty acid component. Preferably, however, the amount of fatty acid is less than 5 % by weight of the composition, more preferably less than 4 %. Preferred saturated fatty acids have from 10 to 16, more preferably 12 to 14 carbon atoms. Preferred unsaturated fatty acids are oleic acid and palmitoleic acid. Preferred compositions contain an inorganic or organic builder. Examples of inorganic builders include the phosphorous-based builders, e.g., sodium tripolyphosphate, sodium pyrophosphate, and aluminosilicates (zeolites). Examples of organic builders are represented by polyacids such as citric acid, nitrilotriacetic acid, and mixtures of tartrate monosuccinate with tartrate disuccinate. Preferred builders for use herein are citric acid and alk(en)yl-substituted succinic acid compounds, wherein alk(en)yl contains from 10 to 16 carbon atoms. An example of this group of compounds is dodecenyl succinic acid. Polymeric carboxylate builders inclusive of polyacrylates, polyhydroxy acrylates and polyacrylates/polymaleates copolymers can also be used. The compositions herein can contain a series of further optional ingredients which are mostly used in additive levels, usually below about 5 %. Examples of the like additives include : suds regulants, opacifiers, agents to improve the machine compatibility in relation to enamel-coated surfaces, bactericides, dyes, perfumes, brighteners and the like. In addition to HEDP, the preferred liquid compositions herein may further contain other chelants at a level from 0,05 % to 5 %. These chelants include polyaminocarboxylates such as ethylenediaminotetracetic acid, diethylenetriaminopentacetic acid, ethylenediamino disuccinic acid or the water-soluble alkali metals thereof. Other additives include organo-phosphonic acids; particularly preferred are ethylenediamine tetra(methylenephosphonic acid), hexamethylenediamine tetra(methylenephosphonic acid), diethylenetriamine penta(methylenephosphonic acid) and aminetri(methylenephosphonic acid). Bleach stabilizers such as ascorbic acid, dipicolinic acid, sodium stannates and 8-hydroxyquinoline can also be included in these compositions, at levels from 0.01 % to 1 %. The beneficial utilization of the claimed compositions under various usage conditions can require the utilization of a suds regulant. While generally all detergent suds regulants can be utilized preferred for use herein are alkylated polysiloxanes such as dimethylpolysiloxane also frequently termed silicones. The silicones are frequently used in a level not exceeding 1.5 %, most preferably from 0.05 % to 1.0 %. It can also be desirable to utilize opacifiers in as much as they contribute to create a uniform appearance of the concentrated liquid detergent compositions. Examples of suitable opacifiers include : polystyrene commercially known as LYTRON 621 manufactured by MONSANTO CHEMICAL CORPORATION. The opacifiers are frequently used in an amount from 0.3 % to 1.5 %. The liquid detergent compositions of this invention can further comprise an agent to improve the washing machine compatibility, particularly in relation to enamel-coated surfaces. It can further be desirable to add from 0.1 % to 5 % of known antiredeposition and/or compatibilizing agents. Examples of the like additives include : sodium carboxymethylcellulose; hydroxy-C₁₋₆-alkylcellulose; polycarboxylic homo- or copolymeric ingredients, such as : polymaleic acid; a copolymer of maleic anhydride and methylvinylether in a molar ratio of 2:1 to 1:2; and a copolymer of an ethylenically unsaturated monocarboxylic acid monomer, having not more than 5, preferably 3 or 4 carbon atoms, for example (meth)-acrylic acid, and an ethylenically unsaturated dicarboxylic acid monomer having not more than 6, preferably 4 carbon atoms, whereby the molar ratio of the monomers is in the range from 1:4 to 4:1, said copolymer being described in more detail in European Patent Application 0 066 915, filed May 17, 1982. The compositions according to the invention have a pH at room temperature of at least 8.5, preferably at least 9.0, more preferably at least 9.5, most preferably at least 10. Liquid detergent compositions according to the present invention can be obtained by mixing together the mentioned ingredients. Examples The following experiments have been made and will illustrate the invention. Example 1 The following basic formulation is prepared : Ingredients % by weight Ethanol 13 Linear dodecylbenzene sulfuric acid 9 Sodium cocoyl sulfate 1 Condensation product of 1 mole of oxoalcohol and 7 7 moles of ethylene oxide Citric acid 0.7 Oleic acid 3 Sodium hydroxide 6 Sodium formate 0.9 Proteolytic enzyme (8KNPU/g) 0.5 Sodium perborate monohydrate 14.5 Stabilizing system 0.75 Water and minors up to 100% Three different stabilizing systems are added to this basic formulation : DETMPA HMTMPA HEDP Each of these three testing formulations are then either not contaminated contaminated with 1 ppm Mn contaminated with 75 ppm Fe The amounts of added metals are higher than those encountered in practical conditions; this excess is designed to obtain accelerated experimental measures. Contamination is obtained by adding parts of a stock solution of metal ions (Mn²⁺ from MnCl₂ or Fe³⁺ from FeCl₃) on top of the finished product. Finally the compositions are stored at 50°C and decomposition of the peroxygen is measured as a function of storage time. Here again, the experimental temperature is higher than a usual storage temperature in order to obtain accelerated experimental measurements. Decomposition of the peroxygen is measured via the available oxygen in the finished product and results are given as a percentage of the initial available oxygen which remains. The initial available oxygen in the finished product is calculated by the formula : During the experiments, the standard iodometric method, as described for instance in "Methoden der Organischen Chemie" by Houben Weyl, 1953, Vo. 2, page 562 is suitable to measure the available oxygen in the finished product. The results are : % of initial available oxygen left contamination Basic formulation with DETMPA with HMTMPA with HEDP no metal 76% after 1 month 76% after 1 month 83% after 1 month 1 ppm Mn 0.1% after 1 week 0% after 1 week 89% after 1 week 75 ppm Fe 0% after 1 week 0% less than 1 week 90% after 1 week This result panel shows that - HEDP is more efficient than other phosphonates in stabilizing the peroxygen compounds, even under normal circumstances (when there is no metal contamination) - HEDP is very efficient against metal contamination, even under the extreme conditions used in this test. Example 2 The following basic formulation is prepared : Ingredients % by weight Ethanol 4 Linear dodecylbenzene sulfonic acid 9 Condensation product of 1 mole of C₁₃-C₁₅ 7 oxoalcohol and 5 moles of ethylene oxide C₁₂-C₁₄ (2 hydroxyethyl) dimethyl ammonium chloride 0.5 Dodecenyl/Tetra decenyl succinic acid 10 Citric acid 2.8 Sodium hydroxide 6 Sodium formate 1.6 Proteolytic enzyme (8KNPU/g) 0.5 Sodium perborate monohydrate 14.5 stabilizing system 0.67 water and minors up to 100% Two different stabilizing systems are added to this basic formulation : DETMPA HEDP Each of these two formulations are then either not contaminated contaminated with 0.5 ppm Mn contaminated with 50 ppm Fe All other experimental conditions and measures are the same as in example 1 : The results are : % of initial available left contamination Basic formulation with DETMPA with HEDP no metal 50% after 1 month 75% after 1 month 0.5 ppm Mn 0% after 2 weeks 75% after 2 weeks 50 ppm Fe 17% after 1 week 85% after 1 week

Claims: An aqueous liquid detergent composition having a ph of at least 8.5 at room temperature, containing from 5% to 60% by weight of an organic surface active agent or mixtures thereof, a solid water-soluble peroxygen compound and a diphosphonate, characterized in that said diphosphonate is hydroxy-ethyliden-1,1-diphosphonic acid, in amounts of from 0.01% to 5% by weight. A liquid detergent composition according to claims 1 wherein the amount of hydroxy-ethylidene-1,1 diphosphonic acid is from 0.05% to 1% A composition according to claim 1 or 2, wherein the amount of hydroxy-ethylidene-1,1 diphosphonic acid is 0.25%. A composition according to any of the preceding claims characterized in that it further contains diethylene tri-amine penta (methylene phosphonic acid). A composition according to any of the preceding claims, characterized in that it has a pH of at least 9.0 preferably 9.5, more preferably at least 10. A composition according to any of the preceding claims characterized in that the peroxygen compound is a perborate. A composition according to claim 6 wherein the perborate is present in the form of particles having a diameter of from 0,1 to 20 micrometers. A composition according to any of the preceding claims, characterized in that the perborate particles have been formed by recrystallization of a perborate monohydrate. A composition according to claim 5, characterized in that the peroxygen compound is a percarbonate. A composition according to any of the preceding claims characterized in that it contains a water miscible organic solvent. A composition according to any of the preceding claims containing less than 4% fatty acid.

Inventors: BOUTIQUE JEAN-POL, BOUTIQUE, JEAN-POL
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1990
Main classification: C11D3
IPC codes: C11D3, D06L3, D06L1