A PROCESS EMPLOYING AN AMINE OXIDE/ACID PREMIX FOR MAKING LAUNDRY DETERGENT COMPOSITIONS

Abstract: Disclosed is a process for making a solid laundry detergent composition containing one or more amine oxide surfactants. The process comprises mixing an amine oxide component and an acid to form a premix; and mixing the premix, an anionic surfactant and an alkali salt. Further disclosed is a product made by the subject process. Further disclosed is a composition consisting essentially of an amine oxide component and an acid, for use in the subject process.

Description: A PROCESS EMPLOYING AN AMINE OXIDE / ACID PREMIX FOR MAKING LAUNDRY DETERGENT COMPOSITIONS BACKGROUND In societies where mechanical washing machines are not common, laundry detergent bars comprising synthetic organic surfactants and detergency builders are used in the laundering of clothes. Synthetic laundry bars typically comprise a synthetic anionic surfactant such as the alkali metal salt of an alkyl benzene sulfonic acid or alkali metal salt of an alkyl sulfate and one or more alkaline builders such as alkali metal polyphosphates, carbonates or silicates. Technical developments in the field of laundry detergent bars have concerned formulating bars which are effective in cleaning clothes; which have acceptable sudsing characteristics in warm and cool water and in hard and soft water; which have acceptable in-use wear rates, hardness, durability, and feel; which have low smear; and which have a pleasing odor and appearance. Methods for making laundry detergent bars are also well known in the art. Known laundry bars and methods for making laundry bars include those disclosed in: U.S. Patent 3,178,370 (Okenfuss, issued April 13, 1965); and Philippine Patent 13,778 (Anderson, issued September 23, 1980). Amine oxide surfactants are commonly used in liquid cleaning compositions to boost and maintain suds formation, and/or improve cleaning, and/or improve mildness to skin. Such compositions include, for example, laundry and dishwashing detergent compositions. However, while a laundry cleaning product formula can be very effective in delivering desired attributes, it may not qualify as a usable product if it also has serious processability problems. For example, the addition of high active (solid or paste) or dilute (liquid) form amine oxides have proven difficult to properly incorporate into a solid detergent composition. Even if such amine oxides are successfully incorporated, the final product lacks acceptable physical properties. Based on the foregoing, there is a need for a laundry detergent bar which comprises an amine oxide, yet maintains acceptable physical properties; as well as a process for making such a laundry detergent bar composition. SUMMARY The present invention relates to a process for making a solid laundry detergent containing one or more amine oxide surfactants. The process comprises mixing an amine oxide component and an acid to form a premix; mixing the premix, an anionic surfactant and an alkali salt. In the case of a laundry detergent bar, the resulting composition is formed into a bar. In the case of a granular laundry detergent, the resulting composition is formed into granules. The present invention further relates to a product made by the subject process. The present invention further relates to a composition consisting essentially of an amine oxide and an acid, for use in the subject process. These and other features, aspects, and advantages of the present invention will become evident to those skilled in the art from a reading of the present disclosure. DETAILED DESCRIPTION While the specification concludes with claims which particularly point out and distinctly claim the invention, it is believed the present invention will be better understood from the following description. All cited references are incorporated herein by reference in their entireties. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention. All percentages are by weight of total composition unless specifically stated otherwise. All ratios are weight ratios unless specifically stated otherwise. Herein, "alkenyl" means a carbon-containing chain, preferably from about C < |o to about C20. more preferably from about C12 to about C « |8- more preferably still from about C12 to about C-jø . which may be straight, branched or cyclic, preferably branched or straight, more preferably straight; substituted (mono- or poly-) or unsubstituted; and monounsaturated {i.e., one double or triple bond in the chain), or polyunsaturated {i.e., two or more double bonds in the chain, two or more triple bonds in the chain, or one or more double and one or more triple bonds in the chain), preferably monounsaturated Herein, "alkyl" means a carbon-containing chain, preferably from about C-jo to about C20. more preferably from about C-12 to about C < |8- more preferably still from about C-12 to about C-iø; which may be straight, branched or cyclic, preferably straight or branched, more preferably straight; substituted (mono- or poly-) or unsubstituted; and saturated. Herein, "comprising" means that other steps and other ingredients which do not affect the end result can be added. This term encompasses the terms "consisting of and "consisting essentially of. Herein, "coconut oil" is used in connection with materials with fatty acid mixtures which typically are linear and have an approximate carbon chain length distribution of about 8% Cs, 7% C-|o. 48% C-|2. 7% C14, 9% C^Q, 2% C18. 7% oleic, and 2% linoleic (the first six fatty acids listed being saturated). Other sources having similar carbon chain length distribution in their fatty acids, such as palm kernel oil and babassu oil, are included within the term coconut oil. Herein, "LAS" means linear alkyl benzene sulfonate. Herein, "solid laundry detergent" means a granular laundry detergent or a laundry detergent bar. Herein, "tallow" is used in connection with materials with fatty acid mixtures which typically are linear and have an approximate carbon chain length distribution of 2% C<|4, 29% C^Q, 23% C-|8 > 2% palmitoleic, 41 % oleic, and 3% linoleic (the first three fatty acids listed are saturated). Other mixtures with similar distribution, such as those from palm oil and those derived from various animal tallow and lard, are also included within the term tallow. The tallow can also be hardened {i.e., hydrogenated) to convert part or all of the unsaturated fatty acid moieties to saturated fatty acid moieties. In accordance with the present invention, it has been found that a new process in manufacturing laundry detergent compositions (e.g., bars or granules) containing an amine oxide component minimizes the creation of any undesired physical properties otherwise associated with other methods of incorporating an amine oxide component into such a composition. This new process employs premixing an amine oxide and an acid. Specifically, the process of the present invention comprises mixing an amine oxide and an acid to form a premix; mixing the premix, an anionic surfactant and an alkali salt; and forming the resulting composition into a bar. The present invention further relates to a laundry bar made by the subject process. The present invention further relates to a granular laundry detergent made by the subject process. The present invention further relates to a premix composition consisting essentially of an amine oxide component and an acid, for use in the subject process. This premix is formed by mixing an amine oxide component with an acid. In a preferred embodiment, the premix composition is in the form of a paste. Herein, "paste" means a soft viscous mass of liquid. The amine oxide component / acid premix preferably contains water, amine oxide component and acid. Preferably, the premix contains from about 1 % to about 80% water, more preferably from about 5% to about 50%, more preferably still from about 20% to about 40%. Preferably, the total combined percent of amine oxide component and acid in the premix is from about 20% to about 80%, more preferably from about 30% to about 70%, more preferably still about 65%. The ratio of amine oxide component to acid is from about 25:1 to about 1 :4, more preferably from about 3:1 to about 1 :1. In one embodiment, the ratio of amine oxide component is preferably greater than the ratio of acid. A. Amine Oxide Component The amine oxide component may be either an amine oxide, a high active amine oxide complex, or mixtures thereof. Amine oxide surfactants for use in the present process preferably have the formula R1 R2R3NO, wherein R1 is a substituted or unsubstituted alkyl or alkenyl preferably containing from about 8 to about 30 carbon atoms; more preferably from about 8 to about 18; more preferably from about 12 to about 18. R 2 and R3 are independently substituted or unsubstituted alkyl or alkenyl groups preferably containing from about 1 to about 18 carbon atoms, more preferably from about 1 to about 4. More preferably, R and R^ are independently methyl groups; examples of such amine oxides include, dodecyldimethyl amine oxide, tetradecyldimethyl amine oxide, hexadecyldimethyl amine oxide, octadecyldimethyl amine oxide, and coconutalkyldimethyl amine oxides. Examples of suitable amine oxides for use in the present process include dodecyldimethyl amine oxide, tridecyldimethyl amine oxide, tetradecyldimethyl amine oxide, pentadecyldimethyl amine oxide, hexadecyldimethyl amine oxide, heptadecyldimethyl amine oxide, octadecyldimethyl amine oxide, dodecyldiethyl amine oxide, tetradecyldimethyl amine oxide, hexadecyldiethyl amine oxide, octadecyldiethyl amine oxide, dodecyldipropyl amine oxide, tetradecyldipropyl amine oxide, hexadecyldipropyl amine oxide, octadecyldipropyl amine oxide, dodecyldibutyl amine oxide, tetradecyldibutyl amine oxide, hexadecyldibutyl amine oxide, octadecyldibutyl amine oxide, dodecylmethylethyl amine oxide, tetradecylethylpropyl amine oxide, hexadecylpropylbutyl amine oxide, and octadecylmethylbutyl amine oxide. Preferred amine oxides include, C12-C18 alkyl dimethyl amine oxides, more preferably C-|4-C < |6- Another preferred amine oxide is ADMOX™, which is a C14 amine oxide dihydrate. ADMOX™ and other amine oxides useful in the present process are set forth in U.S. Patent No. 5,292,955 (Smith and Sauer, issued March 8, 1994). Also useful are amine oxide surfactants made by the oxidation of tertiary amines prepared from mixed alcohols obtainable from coconut oil. Such coconutalkyl amine oxides are preferred from an economic standpoint inasmuch as it is not necessary for the present purposes to separate the mixed alcohol fractions into their pure components to secure the pure chain length fractions of the amine oxides. In a preferred embodiment, the amine oxide is a liquid amine oxide formulation. The percentage of amine oxide in the liquid amine oxide formulation as well as the type of amine oxide are not critical to the successful operation of the instant process, or the resulting laundry detergent composition. Accordingly, any known or conventional liquid amine oxide formulation can be used. Preferably, liquid amine oxide formulations useful in the present invention have up to 50% amine oxide, more preferably from about 1% to about 50%, more preferably still from about 20% to about 40%. It is understood, however, that formulations containing higher or lower concentrations of amine oxide can also be used in the present process. However, more concentrated formulations are preferred from a manufacturing cost standpoint. The remainder of the liquid amine oxide formulation will typically, and preferably, be water. Less preferred liquid formulations are single phase mixtures of water and water-miscible solvents. Liquid amine oxide formulations for use in the present process can be prepared by known and conventional methods. Such methods normally involve the controlled oxidation of tertiary amines to the corresponding amine oxide using a strong oxidizing agent. A preferred oxidizing agent is hydrogen peroxide. A dilute, or preferably concentrated (30% by weight of more), hydrogen peroxide solution is added in a stochiometric or greater amount to a liquid solution containing the tertiary amine for conversion thereof to the amine oxide. Reaction rates and amine oxide yields can be improved by incorporation of catalysts and or chelating agents well known in the surfactant art for this particular application. Methods for making amine oxide surfactants are described, for example, in U.S. Patent 3,215,741 (Chadwick, issued November 2, 1965), U.S. Patent 3,223,647 (Drew and Voss, issued December 14, 1965), British Patent 437,566 (issued October 31 , 1935), and U.S. Patent 4,565,891 (Correa and Riley, issued July 19, 1984). In an alternative embodiment, in combination with or in place of the above discussed amine oxides {i.e., non-complexed amine oxides), high active amine oxide complexes are used in the present process. Generally speaking, such high active amine oxide complexes include solid amine oxide surfactant compositions comprising an amine oxide and a complexing acid selected from the group consisting of saturated carboxylic acid with at least 5 carbon atoms, unsaturated carboxylic acid with at least 5 carbon atoms, phosphonic acid, and mixtures thereof. More specifically, the amine oxide of such a complex preferably has the formula R 1 1 R 12 R13NO, where R 1 1 is a substituted or unsubstituted alkyl or alkenyl group containing from about 6 to about 30 carbon atoms and Groups R1 and R13 are each substituted or unsubstituted alkyl or alkenyl groups containing from about 1 to about 18 carbon atoms. The complexing acid of such a complex preferably is selected from the group consisting of citric acid, polyacrylic acid, malonic acid, adipic acid, oxalic acid, glutaric acid, pthalic acid, lauric acid, oleic acid, benzoic acid, and butyric acid, tetra sodium pyrophosphate (TSPP), sodium tripolyphosphate (STPP), diethylene triamine penta methyl phosphonic acid, hydroxyethane diphosphonic acid, ethylenediamine tetra methylene phosphonic acid, and mixtures thereof. Such complexes may be prepared by admixing the complexing acid with an amine oxide surfactant formulation by admixing 1 mole of complexing acid with X mole(s) of amine oxide, where X is from about 1 to about equal to the number of acid groups of the complexing acid. The pH of the admixture is from about 1 to about 3, whereby a visible precipitate in the admixture is formed. The formed precipitate is separated from the admixture, preferably by mechanical means, and allowed to dry. The separated precipitate forms the solid compositions of the present invention, which solid compositions consist of the amine oxide and complexing acid described above. Other high active amine oxide complexes useful in the present invention include those disclosed in U.S. Patent 5,399,296 (Wierenga et al., issued March 21 , 1995). The amount of amine oxide component used in the laundry composition making process of the present invention (by weight of the resulting laundry detergent composition) is preferably from about 1% to about 50%, more preferably from about 0.5% to about 30%, more preferably still from about 0.9% to about 25%. More preferably, particularly with respect to making laundry detergent bar compositions, the amount of amine oxide component is preferably from about 1% to about 30%, more preferably from about 0.5% to about 10%, more preferably still from about 0.9% to about 4%. B. Acid One or more acids are used in the present process to form the acid / amine oxide premix. Such acids useful in the present process preferably include carboxylic acids, phosphoric acids, sulfuric acids, acid precursors of anionic surfactants, or mixtures thereof; more preferably citric acid, acetic acid, phosphoric acid, acid pyrophosphate, sulfuric acid, the acidic form of linear alkyl benzene sulfonate (HLAS), the acidic form of alkyl sulfate (HAS), or mixtures thereof; more preferably still, sulfuric acid and HLAS. Preferably the HLAS is an acidic form of C < | < |-C-|8 alky' benzene sulfonates. Preferably the HAS is an acidic form of primary, branched-chain and random C-| 0-C20 alkyl sulfates. The amount of acid precursor of an anionic surfactant used in the present process (by weight of the resulting laundry detergent composition) is preferably from about 1% to about 30%, more preferably from about 2.5% to about 20%. More preferably, particularly with respect to making a laundry detergent bar compositions, the amount of acid precursor of an anionic surfactant is preferably from about 1% to about 10%, more preferably from about 2.5% to about 6%. C. Anionic Surfactants Anionic surfactants useful in the present process include synthetic anionic surfactants and soap. 1. Synthetic Anionic Surfactants Synthetic anionic surfactants which are suitable for use herein include the water-soluble salts, preferably the alkali metal, ammonium and alkylolammonium salts of organic sulfuric reaction products having in their molecular structure an alkyl group containing from about 10 to about 20 carbon atoms and a sulfonic acid or sulfuric acid ester group. (Included herein in the term "alkyl" is the alkyl portion of acyl groups.) Examples of this group of synthetic surfactants are the sodium and potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (C8-18 carbon atoms) such as those produced by reducing the glycerides of tallow or coconut oil; and the sodium and potassium alkyl benzene sulfonates in which the alkyl group contains from about 9 to about 15 carbon atoms, in straight chain or branched chain configuration, e.g., those of the type described in U.S. Patents 2,220,099 and 2,477,383. Especially valuable are linear straight chain alkyl benzene sulfonates in which the average number of carbon atoms in the alkyl group is from about 11 to 13, abbreviated as C^ 1_13 LAS. The alkali metal salts, particularly the sodium salts of these surfactants are preferred. Alkyl benzene sulfonates and processes for making them are disclosed in U.S. Patent Nos. 2,220,099 and 2,477,383. Preferred synthetic anionic surfactants are C < |rj-18 linear alkyl benzene sulfonates, C-|θ-14 alkyl glyceryl ether sulfonates, and C10-I8 a ' sulfates. The amount of synthetic anionic surfactant used in the present process (by weight of the resulting laundry detergent composition) is preferably from about 5% to about 60%, more preferably from about 15% to about 30%. 2. Soaps Herein, "soap" means salts of fatty acids. The fatty acids are linear or branched containing from about 8 to about 24 carbon atoms, preferably from about 10 to about 20 carbon atoms. The average carbon chain length for the fatty acid soaps is from about 12 to about 18 carbon atoms, preferably from about 14 to about 16 carbon atoms. Preferred salts of the fatty acids are alkali metal salts, such as sodium and potassium, especially sodium. Also preferred salts are ammonium and alkylolammonium salts. The fatty acids of soaps useful in the present process are preferably obtained from natural sources such as plant or animal esters; examples include coconut oil, palm oil, palm kernel oil, olive oil, peanut oil, corn oil, sesame oil, rice bran oil, cottonseed oil, babassu oil, soybean oil, castor oil, tallow, whale oil, fish oil, grease, lard, and mixtures thereof. Preferred fatty acids are obtained from coconut oil, tallow, palm oil (palm stearin oil), palm kernel oil, and mixtures thereof. Fatty acids can be synthetically prepared, for example, by the oxidation of petroleum, or by hydrogenation of carbon monoxide by the Fischer-Tropsch process. Alkali metal soaps can be made by direct saponification of the fats and oils or by the neutralization of the free fatty acids which are prepared in a separate manufacturing process. Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium and potassium tallow and coconut soaps. Preferred soap raw materials for present process are soaps made from mixtures of fatty acids from tallow and coconut oil. Typical mixtures have tallow:coconut fatty acid ratios of 85:15, 80:20, 75:25, 70:30, and 50:50; preferred ratios are about 80:20 to 65:35. Preferred soap raw materials for the present process are neat soaps made by kettle (batch) or continuous saponification. Neat soaps typically comprise from about 65% to about 75%, preferably from about 67% to about 72%, alkali metal soap; from about 24% to about 34%, preferably from about 27% to about 32%, water; and minor amounts, preferably less than about 1% total, of residual materials and impurities, such as alkali metal chlorides, alkali metal hydroxides, alkali metal carbonates, glycerin, and free fatty acids. Another preferred soap raw material is soap noodles or flakes, which are typically neat soap which has been dried to a water content of from about 10% to about 20%. The other components above are proportionally concentrated. Soaps are optionally used in the present process at levels of no more than about 70%, by weight of the resulting laundry detergent composition. The amount of soap used in the present process (by weight of the resulting laundry detergent composition) is preferably from about 5% to about 70%, more preferably from about 10% to about 50%. In a preferred embodiment, the final composition contains from about 35% to about 50% soap (more preferably from about 35% to about 40%), from about 5% to about 10% surfactant (more preferably from about 7% to about 10%), and from about 1% to about 4% amine oxide.surfactant (more preferably from about 1.5% to about 3%). Preferably, the surfactant is LAS. Preferably the acid used to make such an embodiment is HLAS. Such an embodiment is believed to provide improved cleaning and sudsing in hard water, good calcium tolerance, and improved prevention of loss of fabric whitening {i.e., prevents fabric from becoming dingy). In another preferred embodiment, the final composition contains from about 20% to about 80% soap (more preferably from about 30% to about 50%), from about 1% to about 5% of alkyl sulfate (more preferably from about 2% to about 3%), and from about 0.5% to about 5% amine oxide (more preferably from about 1% to about 4%). Preferably, the soap is a mixture of fatty acids (preferably from about 10 to about 18 carbon atoms) from tallow and coconut oil. Preferably, the alkyl sulfate has chain lengths of from about 10 to about 18 carbon atoms, more preferably from about 12 to about 14. It is believed such an embodiment provides improved greasy soil removal. D. Alkali Salts The alkali salt used in the present process (in addition to its possible use as a builder and providing alkalinity to the overall composition for improved detergency) serves as a neutralizing agent for the acid precursor of an anionic surfactant which is employed in the present process. Alkali salts useful in the present process include alkali metal carbonates, bicarbonates, and phosphates. Preferred alkali salts include sodium carbonate (soda ash), sodium bicarbonate; more preferably sodium carbonate. The amount of alkali salt used in the present process (by weight of the resulting laundry detergent composition) is preferably from about 2% to about 40%, more preferably from about 10% to about 20%. E. Builders The laundry detergent compositions produced by the present process preferably contain from about 0.5% to about 30%, more preferably from about 5% to about 15% detergent builder. These detergent builders can be, for example, water-soluble alkali-metal salts of phosphate, pyrophosphates, orthophosphates, tripolyphosphates, higher polyphosphates, and mixtures thereof. Preferred builders are a water-soluble alkali-metal salt of tripolyphosphate, and a mixture of tripolyphosphate and pyrophosphate. The builder can also be a non-phosphate detergent builder. Specific examples of non-phosphate, inorganic detergency builders include water-soluble inorganic carbonate and bicarbonate salts. The alkali metal (e.g., sodium and potassium) carbonates, bicarbonates, and silicates are particularly useful herein. Specific preferred examples of builders include sodium tripolyphosphates (STPP) and tetra sodium pyrophosphates (TSPP), and mixtures thereof. Other specifically preferred examples of builders include zeolites and polycarboxylates, and co-polymers of acrylic acid and maleic acid. Granular formulations typically comprise from about 10% to about 80%, more typically from about 15% to about 50% by weight, of the detergent builder. F. Moisture The laundry detergent bars made by the present process preferably comprise from about 0.5% to about 30% of moisture, more preferably from about 1% to about 5%. G. Additional Ingredients The detergent compositions produced by the present process may further include other ingredients commonly used in detergent products. A typical listing of the classes and species of optional surfactants, (e.g. nonionic, zwitterionic and amphoteric surfactants) optional alkaline builders such as sodium carbonate trisodium phosphate sodium silicate, etc. and other ingredients useful herein appears in U.S. Pat. No. 3,664,961 , issued to Norris on May 23, 1972, and EP 550,652, published on April 16, 1992. Such optional surfactants, if present, can be included at levels up to a total of about 10%, preferably about 0.5-3%. A preferred additional component in the laundry detergent composition is a bleach component. The bleaching component can be a source of "OOH group, such as sodium perborate monohydrate, sodium perborate tetrahydrate and sodium percarbonate. Sodium percarbonate (2Na2CO3-3H2O2) is preferred since it has a dual function of both a source of HOOH and a source of sodium carbonate. Another optional bleaching component is a peracid per se, such as a formula: CH3(CH2)w-NH-C(O)-(CH2)zCO3H wherein z is from 2 to 4 and w is from 4 to 10. The bleaching component can contain, as a bleaching component stabilizer, a chelating agent of polyaminocarboxylic acids, polyaminocarboxylates such as ethylenediaminotetraacetic acid, diethylenetriaminopentaacetic acid (DTPA), and ethylenediaminodisuccinic acid, and their salts with water-soluble alkali metals. The bleach components, if any, can be added to the laundry detergent composition, if any, at a level up to 20%, preferably from about 1% to about 10%, more preferably from about 2% to about 6%. Mixtures of bleaching agents can also be used. Peroxygen bleaching agents, the perborates, the percarbonates, etc., are preferably combined with bleach activators, which lead to the in situ production in aqueous solution {i.e., during the washing process) of the peroxy acid corresponding to the bleach activator. Various nonlimiting examples of activators are disclosed in U.S. Patent 4,915,854, issued April 10, 1990 to Mao et al, and U.S. Patent 4,412,934. The nonanoyloxybenzene sulfonate (NOBS) and tetraacetyl ethylene diamine (TAED) activators are typical, and mixtures thereof can also be used. See also U.S. 4,634,551 for other typical bleaches and activators useful herein. A preferred additional ingredient is a fabric softening clay, preferably a smectite-type clay and a clay flocculating agent, having a high molecular weight greater than about 100,000. Soil suspending agents may be additionally used. In the present invention, their use is balanced with the fabric softening clay/clay flocculating agent combination to provide optimum cleaning and fabric softening performance. One such soil suspending agent is an acrylic/maleic copolymer, commercially available as SOKALAN®, from BASF Corp. Other soil suspending agents include polyethylene glycols having a molecular weight of about 400 to 10,000, and ethoxylated mono- and polyamines, and quaternary salts thereof. A particularly preferred additional component of the present invention is a detergent chelant. Such chelants are able to sequester and chelate alkali cations (such as sodium, lithium and potassium), alkali metal earth cations (such as magnesium and calcium), and most importantly, heavy metal cations such as iron, manganese, zinc and aluminum. Preferred cations include sodium, magnesium, zinc, and mixtures thereof. The detergent chelant is particularly beneficial for maintaining good cleaning performance and improved surfactant mileage, despite the presence of the softening clay and the clay flocculating agent. The detergent chelant is preferably a phosphonate chelant, particularly one selected from the group consisting of diethylenetriamine penta(methylene phosphonic acid), ethylene diamine tetra(methylene phosphonic acid), and mixtures and salts and complexes thereof, and an acetate chelant, particularly one selected from the group consisting of diethylenetriamine penta(acetic acid), ethylene diamine tetra(acetic acid), and mixtures and salts and complexes thereof. Particularly preferred are sodium, zinc, magnesium, and aluminum salts and complexes of diethylenetriamine penta(methylene phosphonate) diethylenetriamine penta (acetate), and mixtures thereof. Preferably such salts or complexes have a molar ratio of metal ion to chelant molecule of at least 1 :1 , preferably at least 2:1. The detergent chelant may be included in the laundry detergent composition at a level up to about 5%, preferably from about 0.1% to about 3%, more preferably from about 0.2% to about 2%, most preferably from about 0.5% to about 1.0%. Another preferred additional component of the laundry detergent composition is fatty alcohol having an alkyl chain of 8 to 22 carbon atoms, more preferably from 12 to 18 carbon atoms. A preferred fatty alcohol has an alkyl chain predominantly containing from 16 to 18 carbon atoms, so-called "high-cut fatty alcohol," which can exhibit less base odor of fatty alcohol relative to broad cut fatty alcohols. Typically fatty alcohol, if any, is present in the laundry detergent composition at up to a level of 10%, more preferably from about 0.75% to about 6%, most preferably from about 2% to about 5%. The fatty alcohol is generally added to a laundry detergent composition as free fatty alcohol. However, low levels of fatty alcohol can be introduced into the laundry detergent compositions as impurities or as unreacted starting material. For example, laundry bars based on coconut fatty alkyl sulfate can contain, as unreacted starting material, from 0.1% to 3.5%, more typically from 2% to 3%, by weight of free coconut fatty alcohol on a coconut fatty alkyl sulfate basis. Another preferred additional component in the laundry bar or granular detergent is a dye transfer inhibiting (DTI) ingredient to prevent diminishing of color fidelity and intensity in fabrics. A preferred DTI ingredient can include polymeric DTI materials capable of binding fugitive dyes to prevent them from depositing on the fabrics, and decolorization DTI materials capable of decolorizing the fugitives dye by oxidation. An example of a decolorization DTI is hydrogen peroxide or a source of hydrogen peroxide, such as percarbonate or perborate. Non-limiting examples of polymeric DTI materials include polyvinylpyrridine N-oxide, polyvinylpyrrolidone (PVP), PVP-polyvinylimidazole copolymer, and mixtures thereof. Copolymers of N-vinylpyrrolidone and N- vinylimidazole polymers (referred to as "PVPI") are also preferred for use herein. The amount of DTI included in the subject compositions, if any, is about 0.05-5%, preferably about 0.2-2%. Another preferred additional component in the laundry detergent composition is a secondary fabric softener component in addition to the softening clay. Such materials can be used, if any, at levels of about 0.1% to 5%, more preferably from 0.3% to 3%, and can include: amines of the formula R4R5R6N, wherein R4 is C5 to C22 hydrocarbyl, R5 and Re are independently C1 to C10 hydrocarbyl. One preferred amine is ditallowmethyl amine; complexes of such amines with fatty acid of the formula R7COOH, wherein R7 is Cg to C22 hydrocarbyl, as disclosed in EP No. 0,133,804; complexes of such amines with phosphate esters of the formula R8θ-P(O)(OH)-ORg and HO- P(O)(OH)-ORg, wherein Rδ and Rg are independently C1 to C20 alkyl of alkyl ethoxylate of the formula -alkyl-(OCH2CH2); cyclic amines such as imidazolines of the general formula 1 -(higher alkyl) amido (lower alkyl)-2- (higher alkyl)imidazoline, where higher alkyl is from 12 to 22 carbons and lower alkyl is from 1 to 4 carbons, such as described in UK Patent Application GB 2,173,827; and quaternary ammonium compounds of the formula R10 R 11 R 12R13N + X " , wherein R-|θ is alkyl having 8 to 20 carbons, Rn is alkyl having 1 to 10 carbons, R-|2 and R13 are alkyl having 1 to 4 carbons, preferably methyl, and X is an anion, preferably Cl" or Br, such as C-|2-13 alkyl trimethyl ammonium chloride. Sodium sulfate is a well-known filler that is compatible with the compositions of this invention. It can be a by-product of the surfactant sulfation and sulfonation processes, or it can be added separately. Other filler materials include bentonite and talc. Calcium carbonate (also known as Calcite) is also a well known and often used filler component of laundry detergent compositions. Fillers include minerals, such as talc and hydrated magnesium silicate-containing minerals, where the silicate is mixed with other minerals, e.g., old mother rocks such as dolomite. Filler materials are typically used, if included, at levels up to 40%, preferably from about 5% to about 25%. Binding agents for holding the laundry detergent composition together in a cohesive, soluble form can also be used, and include natural and synthetic starches, gums, thickeners, and mixtures thereof. Such materials, if included, are typically at levels up to about 3%, preferably about 0.5-2%. Glycerine is commonly incorporated in laundry bar compositions. If included, it is typically at concentrations up to about 3%, preferably about 0.5-1.5%. Optical brighteners are also preferred optional ingredients in laundry detergent compositions of the present invention. Preferred optical brighteners are diamino stilbene, distyrilbiphenyl-type optical brighteners. Preferred as examples of such brighteners are 4,4'-bis{[4-anilino-6-bis(2-hydroxyethyl) amino-1 ,3,5-trizin-2-yl]amino}stilbene-2,2'-disulfonic acid disodium salt, 4-4'- bis(2-sulfostyryl) biphenyl and 4,4'-bis[(4-anilino-6-morpholino-1 ,3,5-triazin-2-yl) amino]stilbene-2,2'-disulfonic acid disodium salt. Such optical brighteners, or mixtures thereof, can be used at levels in the laundry detergent composition of from about 0.05% - 1.0%. Dyes, pigments, germicides, and perfumes may also be added to the laundry detergent composition. If included, they are typically at levels up to about 0.5%. Another additional component useful in the present process is a photobleach material, particularly phthalocyanine photobleaches which are described in U.S. Patent 4,033,718 issued July 5, 1977. Preferred photobleaches are metal phthalocyanine compounds, the metal preferably having a valance of +2 or +3; zinc and aluminum are preferred metals. Such photobleaches are available, for example, under the tradename TINOLUS or as zinc phthalocyanine sulfonate. The photobleach components, if included, are typically in the subject compositions at levels up to about 0.02%, preferably from about 0.001% to about 0.015%, more preferably from about 0.002% to about 0.01%. Enzymes can also be included in the laundry detergent composition for a variety of purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains from substrates, for the prevention of refugee dye transfer in fabric laundering, and for fabric restoration. Suitable enzymes include proteases, amylases, lipases, cellulases, peroxidases, and mixtures thereof of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin. Preferred selections are influenced by factors such as pH-activity and/or stability optima, thermostability, and stability to active detergents, builders and the like. In this respect bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and fungal cellulases. Suitable examples of proteases are the subtilisins which are obtained from particular strains of B. subtilis and B. licheniformis. Suitable proteases include ESPERASE® by Novo Industries A S of Denmark, hereinafter "Novo"; ALCALASE® and SAVINASE® from Novo and MAXATASE® from International Bio-Synthetics, Inc., The Netherlands; as well as Protease A as disclosed in EP 130,756 A, January 9, 1985 and Protease B as disclosed in EP 303,761 A, April 28, 1987 and EP 130,756 A, January 9, 1985. See also a high pH protease from Bacillus sp. NCIMB 40338 described in WO 9318140 A to Novo. Amylases suitable herein, include, for example, -amylases described in GB 1,296,839 to Novo; RAPIDASE®, International Bio-Synthetics, Inc. and TERMAMYL®, Novo. Cellulases usable herein include both bacterial and fungal types. Suitable cellulases are also disclosed in GB-A-2.075.028; GB-A-2.095.275 and DE-OS-2.247.832. CAREZYME® and CELLUZYME® (Novo) are especially useful. See also WO 9117243 to Novo. Enzymes are normally incorporated into detergent or detergent additive compositions at levels sufficient to provide a "cleaning-effective amount". The term "cleaning effective amount" refers to any amount capable of producing a cleaning, stain removal, soil removal, whitening, deodorizing, or freshness improving effect on substrates such as fabrics, dishware and the like. In practical terms for current commercial preparations, typical amounts are up to about 5 mg by weight, more typically 0.01 mg to 3 mg, of active enzyme per gram of the detergent composition. Stated otherwise, the compositions herein will typically comprise from 0.001% to 5%, preferably 0.01 %-1% by weight of a commercial enzyme preparation. Protease enzymes are usually present in such commercial preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of composition. For certain detergents, such as in automatic dishwashing, it may be desirable to increase the active enzyme content of the commercial preparation in order to minimize the total amount of non-catalytically active materials and thereby improve spotting/filming or other end-results. Higher active levels may also be desirable in highly concentrated detergent formulations. H. Processing 1. Bars In laundry bar making embodiment of the present invention, the process includes mixing an amine oxide component and an acid to form a premix; mixing the premix, an anionic surfactant and an alkali salt; and forming the resulting composition into a bar. The process of the present invention can employ conventional soap or detergent bar making equipment with some or all of the following key equipment: blender/mixer (e.g., ribbon blender), mill, refining plodder (e.g., duplex plodder), two-stage vacuum plodder, logo printer/cutter, cooling tunnel and wrapper. In a typical process, the amine oxide component and acid are mixed in a blender, a planetary mixer, kneader and/or extruder, to form a premix. This premix is mechanically worked to effect homogeneity and to complete the neutralization of the premix. Subsequently, the premix is combined with other raw materials (including anionic surfactant and alkali salt) in a blender. This mixture of premix and other raw materials is referred to as the seat. Additional soap and other optional surfactants are then added, followed by the builder and any additional adjunct ingredients. If desired, polyphosphate can be used as an alkaline salt in the neutralization. The high shear mixing can take from one minute to one hour, with the usual mixing time being from about two to twenty minutes. Preferably, the temperature is from about 74°C to about 80°C. Examples of equipment which may be used for the high shear mixing include, the Sigma Mixer high sheer mixer, manufactured by Fabdecon Engineers, Bombay India; or a plough sheer mixer, manufactured by Littleford Day, Inc., Kentucky, U.S.A. The blender mix is charged to a surge tank. The product is conveyed from the surge tank to the mill. As the mixture is being milled, the mixture is cooled to a temperature of from about 40°C to about 62°C. Preferably, the mixture is cooled by the running of cool water through the mill, which in turn cools the mixture being milled. After milling or preliminary plodding after milling, the product is then conveyed to a double vacuum plodder, operating at high vacuum, e.g., 400 to 740 mm of mercury vacuum, so that entrapped air is removed. The product is extruded and cut to the desired bar length, and printed with the product brand name. The printed bar can be cooled, for example in a cooling tunnel, before it is wrapped, cased, and sent to storage. 2. Granules The amine oxide component / acid premix may be employed in the making of both low density (below 550 g/l) and high density (at least 550 g/l) granular laundry detergent compositions. Such high density detergent compositions typically comprised from about 30% to about 90% of detersive surfactant. Low density compositions can be prepared by standard spray-drying processes. Various means and equipment are available to prepare high density granular detergent compositions. Current commercial practice in the field employs spray-drying towers to manufacture granular laundry detergents which often have a density less than about 500 g/l. Accordingly, if spray drying is used as part of the overall process, the resulting spray-dried detergent particles must be further densified using the means and equipment described hereinafter. In the alternative, the formulator can eliminate spray-drying by using mixing, densifying and granulating equipment that is commercially available. The following is a nonlimiting description of such equipment suitable for use herein. High speed mixer/densifiers can be used in the present process, for example, the device marketed under the trademark "Lodige CB30 Recycler" comprises a static cylindrical mixing drum having a central rotating shaft with mixing/cutting blades mounted thereon. Other such apparatus includes the devices marketed under the trademark "Shugi Granulator" and under the trademark "Drais K-TTP 80". Equipment such as that marketed under the trademark "Lόdige KM600 Mixer", "Fukae High Speed Mixer" and "Food Processor" can be used for further densification. In one mode of operation, the compositions are prepared and densified by passage through two mixer and densifier machines operating in sequence. Thus the desired compositional ingredients can be admixed and passed through a Lodige mixer using residence times of about 0.1 to about 1 minute, then passed through a second Lodige mixer using residence times of about 1 minute to about 5 minutes. In another mode, an aqueous slurry comprising the desired formulation ingredients is sprayed into a fluidized bed of particulate surfactants, the resulting particles can be further densified by passage through a Lόdige apparatus, as noted above. The final density of the resulting particles can be measured by a variety of simple techniques, which typically involve dispensing a quantity of the granular detergent into a container of known volume, measuring the weight of detergent and reporting the density in g/l. The amine oxide component / acid premix is prepared as described above, and then introduced to the low density and high density granular composition making processes where surfactant is normally introduced. In spray-drying processes, it is preferable to add additional water to the premix, either during its formation or after. The resulting slurry will facilitate spray- drying of the surfactant. In processes which do not involve spray-drying, the paste form of the premix is preferred. The following examples further describe and demonstrate the preferred embodiments within the scope of the present invention. The examples are given solely for the purpose of illustration, and are not to be construed as limitations of the present invention since many variations thereof are possible without departing from its spirit and scope. Example 1 This example shows a premix of amine oxide and acid for subsequent use in the solid laundry composition making process of the present invention: Component % by Weight HLAS 60 Tetradecyldimethyl (C14) amine oxide 40 The HLAS and amine oxide are mixed together until a constant viscosity is reached (approximately 30 seconds to 2 minutes of continuous mixing). Example 2 This example shows a premix of amine oxide and acid for subsequent use in the solid laundry composition making process of the present invention: Component % by Weight HLAS 41 Tetradecyldimethyl (C14) amine oxide 59 The HLAS and amine oxide are mixed together until a constant viscosity is reached (approximately 30 seconds to 10 minutes of continuous mixing). Example 3 This example shows a process of the present invention for making a synthetic laundry detergent bar having the following final composition: Component % by Weight NaCFAS 17.85 ADMOX SC-1485 (amine oxide) 4.65 Sodium Carbonate 15.00 Sodium Sulfate 8.55 Sodium Tripolyphosphate (STPP) 11.60 Calcium Carbonate 30.00 Coco Fatty Alcohol 1.00 Glycerine 1.00 Titanium Dioxide 1.00 Diethylenetriamine pentacarboxylic acid 0.70 Zeolite 1.00 Substituted Methyl Cellulose 0.50 Fluorescent Whitening Agents 0.20 Perfume 0.50 Moisture 4.84 Other conventional ingredients. balance to 100 Combine ADMOX and sulfuric acid, mixing for 2 min. to form a premix. Subsequently combine soda ash, sodium coconut fatty alcohol sulfate, STPP, and zeolite with the premix; and mix for 3 minutes (this mixture is referred to as the "seat"). Add diethylenetriamine pentacarboxylic acid and coco fatty alcohol. Continue mixing for 30 seconds. Add titanium dioxide and calcium carbonate. Then add brighteners, substituted methyl cellulose, glycerine and other conventional/minor ingredients. Subsequently add perfume when desired batch consistency is met. Drop the batch and form into bars. Example 4 This example shows a process of the present invention for making a synthetic and soap laundry detergent bar having the following final composition: Component % by Weight NaLAS 2.50 Soap 47.50 Soda Ash 8.50 Water 1.95 Fluorescent Whitening Agent 0.02 Bluing Agent 0.10 Substituted Methyl Cellulose 0.50 ADMOX SC-1485 1.80 Sodium Sulfate 5.00 Talc 4.22 Perfume 0.260 Other conventional ingredients balance to 100 Combine ADMOX and HLAS, mixing for 2 min., to form a premix. Subsequently combine soda ash, and 50% of talc with the premix; and mix for 30 seconds (this mixture is referred to as the "seat"). Add water over a 30 second period, and mix for 2 minutes. Add fluorescent whitening agent and substituted methyl cellulose, and mix for 30 seconds. Add soap and mix for 3 minutes (addition time inclusive). Add sodium sulfate and balance of talc, and mix for 1 minute. Add perfume, and mix for 30 seconds. Drop the batch and form into bars. Example 5 This example shows a process of the present invention for making laundry detergent granules having the following final composition: Component % by Weight NaLAS 18 Fluorescent Whitening Agent 0.2 Bluing Agent 0.0045 Substituted Methyl Cellulose 0.4 ADMOX SC-1485 0.6 Zeolite 22.5 Chelant 0.9 Perborate 3 NOBS 2.5 Soil Dispersing Agent 0.25 Savinase 0.7 Termamyl 0.36 Carezyme 0.35 PVPI 0.1 PVP 0.3 Other conventional ingredients balance to 100 Combine the ADMOX and the NaLAS, mixing for 2 min., to form a premix. Subsequently combine the soda ash, and 50% of the talc with the premix; and mix for 30 seconds. Add additional water until a slurry is formed. The slurry is subsequently spray-dried in a tower to form low density granules of 500 g/l. Example 6 This example shows a process of the present invention for making laundry detergent granules having the following final composition: Component % by Weight HLAS 15.9 Cocounutalkyl amine oxides 22.5 Sodium carbonate 38.0 Precipitated Silica Sipernat D22S 17.7 Other conventional ingredients balance to 100 Combine the coconutalkyl amine oxides and the HLAS, mixing for 10 minutes, to form a premix. Combine the soda ash and Sipernat with the premix, and mix for 15 seconds using a Tilt-a-pin mixer (supplied by Processall(. The blender mix is charged to Tilt-a-plow mixer (supplied by Processall) and mixed for 2 minutes. The mixture is subsequently charged to a fluid bed dryer supplied by NIRO Inc. for 15 minutes at 120°C. Example 7 This example shows a process of the present invention for making laundry detergent granules having the following final composition: Component % by Weight HLAS 11.8 Coconutalkyl amine oxides 16.7 Sodium Carbonate 36.9 Precipitated Silica Sipernat D22S 15.0 Zeolite Type A 13.8 Other conventional ingredients balance to 100 Combine the coconutalkyl amine oxides and the HLAS, mixing for 10 minutes, to form a premix. Combine the sodium carbonate and Sipernat with the premix. Mix for 30 seconds using a Food Processor (TK-55, supplied by Tesukomu, Japan). Subsequently charge the mixture to a Fluid Bed Dryer (supplied by NIRO Inc.) for 15 minutes at 120°C. Example 8 This example shows a process of the present invention for making laundry detergent granules having the following final composition: Component % by Weight HLAS 11.8 Coconutalkyl amine oxides 16.7 Sodium Sulfate 36.9 Precipitated Silica Sipernat D22S 15.0 Zeolite Type A 13.8 Other conventional ingredients balance to 100 Combine the coconutalkyl amine oxides and the HLAS, mixing for 10 minutes, to form a premix. Combine the sodium sulfate and Sipernat with the premix. Mix for 30 seconds using a Food Processor (TK-55, supplied by Tesukomu, Japan). Subsequently charge the mixture to a Fluid Bed Dryer (supplied by NIRO Inc.) for 15 minutes at 120°C. Liquid amine oxide is typically very difficult to incorporate into solid detergent compositions via conventional laundry bar and granule manufacturing processes. A major contributor to this difficulty is the huge amount of moisture such amine oxides bring into the bar formulation. This moisture results in difficulty in processing and corresponding bar softness, and/or granule stickiness, issues. However, by premixing liquid amine oxide with acid, as in the present invention, the resulting premix can be readily incorporated into solid detergent bar and/or granule compositions, particularly laundry detergent bar compositions. Consequently, the aspects and embodiments of the present invention set forth in this document have many advantages, including improved physical properties, versus laundry detergent bars and/or laundry detergent granule compositions comprising an amine oxide made by an alternate process. Such improved physical properties may include, improved homogeneity, reduced softness, easier processing, easier packing and shipping of resulting product, and better economy in use. Bar softness is undesirable for a number of reasons. For example, it causes difficulties in subsequent bar processing steps. Among other things, if a bar is too soft, it cannot be properly removed from the plodder. In addition, a soft bar is subject to deformation during packaging and/or shipping. Although a soft bar will likely harden over a period of about 2 weeks, a bar that hardens quickly coming out of the plodder can be immediately shipped and packed. Even if one developed an economical means of packing/shipping soft bars which avoided deformation, a soft bar used by a consumer poses several undesirable characteristics. For example, the consumer has less control over application of the detergent to the fabric. A harder bar is less malleable, again providing the consumer with more control over detergent delivery. Laundry bars made with liquid amine oxide employing the present process have bar hardness/firmness properties comparable to laundry bars made with solid amine oxide via conventional processing. The laundry bars produced by the present process have many additional advantages, including improved sudsing, mildness to the user's hands, and improved cleaning, yet do not present serious processability problems. Without intending to be bound by theory, it is believed that an ion-pair is formed between the acid and the amine oxide when the latter comes in contact with the former. It is believed the ion pair is brought about by electrostatic attraction between the acid molecule upon the loss of its hydronium ion and the protonated atom of the amine oxide. For example, with respect to a premix of HLAS and an amine oxide, an ion-pair is believed to be brought about by electrostatic attraction between the negatively charged sulfonate of HLAS and the protonated oxygen atom of the amine oxide. The protonation comes from the hydronium ion of HLAS. More specifically: Wherein R^ , R2 and R^ are as defined above, and R^ is an alkyl. It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to one skilled in the art without departing from the scope of the present invention.

Claims: WHAT IS CLAIMED IS: 1. A process for making a laundry detergent bar containing one or more amine oxide surfactants, the process comprising: a) mixing an amine oxide component and an acid to form a premix; b) mixing i) the premix, ii) an anionic surfactant, and iii) an alkali salt; and c) forming the resulting composition into a bar. 2. The process of Claim 1 , wherein the anionic surfactant is a synthetic anionic surfactant. 3. The process of Claim 2, wherein the anionic surfactant is a linear alkyl benzene sulfonate or an alkyl sulfonate. 4. The process of Claim 3, wherein the acid is sulfuric acid or an acid precursor of linear alkyl benzene sulfonate. 5. The process of Claim 1 , wherein the anionic surfactant is a soap. 6. The process of Claim 5, wherein the acid is sulfuric acid or an acid precursor of linear alkyl benzene sulfonate. 7. A process for making a laundry detergent bar containing one or more amine oxide surfactants, the process comprising: a) mixing an amine oxide component and an acid to form a premix; b) mixing i) the premix, ii) one or more anionic surfactants selected from the group consisting of soap, linear alkyl sulfonate and alkyl sulfonate, and iii) an alkali salt; and c) forming the resulting composition into a bar. 8. A laundry detergent bar produced by the process of Claim 3. 9. A composition consisting essentially of an amine oxide component and an acid. 10. The composition of Claim 9 wherein the acid is sulfuric acid or an acid precursor of linear alkyl benzene sulfonate. 11. A process for making a granular laundry detergent containing one or more amine oxide surfactants, the process comprising: a) mixing an amine oxide component and an acid to form a premix; b) mixing i) the premix, ii) an anionic surfactant, and iii) an alkali salt; and c) forming the resulting composition into granules. 12 • A solid laundry detergent composition comprising an amine oxide component, an acid, an anionic surfactant and an alkali salt; wherein the acid and the amine oxide form an ion pair.

Inventors: TRAJANO TRACE WENDELL DE GUZMA, TRAJANO, TRACE, WENDELL DE GUZMAN
Applicants: PROCTER & GAMBLE, TRAJANO TRACE WENDELL DE GUZMA, THE PROCTER & GAMBLE COMPANY, TRAJANO, TRACE, WENDELL DE GUZMAN
Application year: 1997
Main classification: C11D11
IPC codes: C11D1, C11D10, C11D11, C11D17