HEAVY DUTY LIQUID LAUNDRY DETERGENT COMPOSITION CONTAINING ANIONIC AND AMINE OXIDE SURFACTANTS AND FATTY ACID

Abstract: Heavy duty liquid detergent compositions containing anionic synthetic surfactant, amine oxide semi-polar nonionic surfactant, and fatty acid are disclosed. The compositions are substantially free of alkyl benzene sulfonates. Preferably, the mole ratio of amine oxide surfactant to fatty acid is from about 2:1 to about 1:4. The compositions provide good cleaning performance particularly with respect to greasy/oily stain removal.

Description: HEAVY DUTY LIQUID LAUNDRY DETERGENT COMPOSITION CONTAINING ANIONIC AND AMINE OXIDE SURFACTANTS AND FATTY ACID TECHNICAL FIELD The present invention relates to aqueous heavy duty liquid laundry detergent compositions containing anionic surfactant, amine oxide semi-polar nonionic surfactant, and fatty acid. The composition is substantially free of alkyl benzene sulfonates. The compositions provide good cleaning performance particularly with respect to greasy/oily stain removal. They preferably are clear, homogeneous, and stable liquids. BACKGROUND OF THE INVENTION Greasy and oily soil stains are known to be one of the toughest cleaning problems for consumers in the laundry context. Current commercial laundry products attempt to address this problem through the use of conventional surfactant technology including anionic sulfate or sulfonate surfactants (alkyl sulfates, alkyl polyethoxylate sulfates, alkyl benzene sulfonates) or nonionic surfactants (alcohol ethoxylates, polyhydroxy fatty acid amides). Other attempts have incorporated particular enzymes like lipolytic enzymes into a heavy duty liquid detergent matrix to attack these tough soils and stains. Anionic surfactants including alkyl sulfates, alkyl polyethoxylate sulfates, alkyl benzene sulfonates are known having been disclosed in, e.g., U.S. Patent No. 4,285,841, Barrat et al, issued August 25, 1981, and in U.S. Patent No. 3,919,678, Laughlin et al, issued December 30, 1975. Amine oxide semi-polar nonionic surfactants are well known in the detergent field, particularly in the light duty liquid hand-dishwashing area where high-sudsing surfactants are required, having been disclosed in, e.g., U.S. Patent 4,316,824 (Pancheri), issued February 23, 1982; U.S. Patent 5,075,501 (Borland et al), issued December 24, 1991; and U.S. Patent 5,071,594, (Borland et al), issued December 10, 1991. Fatty acid is a known detergent composition ingredient having been disclosed in, e.g., U.S. Patent 4,561,998 (Wertz et al), issued December 31, 1985. However, none of the above patents disclose, alone or in combination, the unique benefits provided by a detergent composition as set forth below. It has now been found that aqueous, heavy duty liquid detergent compositions containing an anionic surfactant, an amine oxide semi-polar nonionic surfactant and a fatty acid provide good cleaning performance, particularly on greasy/oily soils and stains. The composition must be substantially free of alkyl benzene sulfonates. The fatty acid component in combination with the amine oxide surfactant provides enhanced cleaning of fabrics, especially in the prescribed molar ratios. Therefore, it is an object of the invention herein to provide a aqueous heavy duty liquid laundry detergent composition which provides good cleaning benefits particularly with respect to greasy/oily soils or stains. SUMMARY OF THE INVENTION The present invention encompasses aqueous heavy duty liquid laundry detergent composition comprising, by weight of the composition: (a) from about 10% to about 40% of an anionic synthetic surfactant; (b) from about 0.2% to about 20% of an amine oxide semi-polar nonionic surfactant of the formula: wherein K\ is an alkyl, 2-hydroxyalkyl, or 3-hydroxyalkyl radical in which the alkyl and alkoxy, respectively, contain from about 10 to about 18 carbon atoms; and R2 and R3 are each methyl, ethyl, propyl, isopropyl, or A n wherein A is an ethylene oxide or propylene oxide unit and n is from 1 to about 10; and (c) from about 1% to about 20% of a fatty acid containing from about 10 to about 22 carbon atoms; wherein the pH of said composition is between about 7 and about 9.5 at a concentration of about 10% by weight in water at 20°C and wherein the composition is substantially free of alkyl benzene sulfonates. Preferred compositions herein comprise the amine oxide surfactant and fatty acid in a molar ratio of from about 2:1 to about 1:4. Other preferred compositions further comprise an auxiliary nonionic surfactant, a detergent builder and enzymes. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, it has now been found that an aqueous heavy duty liquid detergent composition comprising anionic surfactant, amine oxide surfactant, and fatty acid in relative proportions specified hereinafter surprisingly provides notable cleaning benefits particularly on greasy/oily stains. When the composition is used full-strength on these stains before washing in a regular load of wash, i.e., in a pre-treat process, the composition provides superior cleaning benefits. The heavy duty liquid laundry detergent compositions herein contain an anionic synthetic surfactant component, amine oxide semi-polar nonionic surfactant, fatty acid, and water as essential ingredients. Anionic Synthetic Surfactant The detergent compositions herein comprise from about 10% to about 40%, preferably from about 15% to about 30%, by weight of the detergent composition, of an anionic synthetic surfactant component. The anionic surfactant component preferably contains alkyl polyethoxylate sulfates, and may contain other non-soap anionic surfactants, or mixtures thereof. The composition herein and, therefore the anionic surfactant component, must be substantially free of alkyl benzene sulfonates. Generally speaking, anionic surfactants useful herein are disclosed in U.S. Patent No. 4,285,841, Barrat et al, issued August 25, 1981, and in U.S. Patent No. 3,919,678, Laughlin et al, issued December 30, 1975, both incorporated herein by reference. Useful anionic surfactants include the water-soluble salts, particularly the alkali metal, ammonium and alkylolammonium (e.g., monoethanolammonium or triethanolammonium) 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 in the term "alkyl" is the alkyl portion of aryl groups.) Examples of this group of synthetic surfactants are the alkyl sulfates, especially those obtained by sulfating the higher alcohols (Cg-Cjg carbon atoms) such as those produced by reducing the glycerides of tallow or coconut oil. Other anionic surfactants herein are the water-soluble salts of: paraffin sulfonates containing from about 8 to about 24 (preferably about 12 to 18) carbon atoms; alkyl glyceryl ether sulfonates, especially those ethers of Cg.jg alcohols (e.g., those derived from tallow and coconut oil); alkyl phenol ethylene oxide ether sulfates containing from about 1 to about 4 units of ethylene oxide per molecule and from about 8 to about 12 carbon atoms in the alkyl group; and alkyl ethylene oxide ether sulfates containing about 1 to about 4 units of ethylene oxide per molecule and from about 10 to about 20 carbon atoms in the al yl group. Other useful anionic surfactants herein include the water-soluble salts of esters of α-sulfonated fatty acids containing from about 6 to 20 carbon atoms in the fatty acid group and from about 1 to 10 carbon atoms in the ester group; water-soluble salts of 2-acyloxy-alkane-l-sulfonic acids containing from about 2 to 9 carbon atoms in the acyl group and from about 9 to about 23 carbon atoms in the alkane moiety; water- soluble salts of olefin sulfonates containing from about 12 to 24 carbon atoms; and β- alkyloxy alkane sulfonates containing from about 1 to 3 carbon atoms in the alkyl group and from about 8 to 20 carbon atoms in the alkane moiety. Particularly preferred anionic surfactants herein are the alkyl polyethoxylate sulfates of the formula RO(C 2 H 4 O) x SO 3 -M + wherein R is an alkyl chain having from about 10 to about 22 carbon atoms, saturated or unsaturated, and the longest linear portion of the alkyl chain is 15 carbon atoms or less on the average, M is a cation which makes the compound water-soluble, especially an alkali metal, ammonium or substituted ammonium cation, and x is from 1 to about 15. The anionic surfactant of the present compositions preferably comprises from about 5% to about 40%, preferably from about 7% to about 36%, most preferably from about 10% to about 25%, by weight of the detergent composition, of alkyl polyethoxylate sulfates as described above. Other preferred anionic surfactants are the non-ethoxylated Cj2-15 primary and secondary alkyl sulfates. Under cold water washing conditions, i.e., less than about 65°F (18.3°C), it is preferred that there be a mixture of such ethoxylated and non-ethoxylated alkyl sulfates. Mixtures of the alkyl sulfates with the above-described paraffin sulfonates, alkyl glyceryl ether sulfonates and esters of a α-sulfonated fatty acids, are also preferred. The anionic surfactant component herein must be substantially free of alkyl benzene sulfonates. As used herein, "substantially free" means that there is no more than about 5% by weight of the particular component. Most preferably, the detergent compositions herein contain no alkyl benzene sulfonates. These include alkylbenzene 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. Patent No. 2,220,099 and No. 2,477,383. Especially troublesome are linear straight chain alkylbenzene sulfonates in which the average number of carbon atoms in the alkyl group is from about 11 to 14. While not intending to be limited by theory, it is believed that the amine oxide surfactant and fatty acid form ion pair complexes in aqueous solutions to provide enhanced cleaning performance of greasy/oily soils or stains. The amine oxide surfactant, however, has a stronger affinity to alkyl benzene sulfonates (in forming the ion pair complexes) than to fatty acid. In the presence of alkyl benzene sulfonates and fatty acid, the amine oxide surfactant will form ion pairs with the alkyl benzene sulfonates over the fatty acid. Ion pairs formed between the amine oxide surfactant and alkylbenzene sulfonates do not provide the enhanced cleaning benefit provided by the amine oxide/fatty acid ion pair. Amine Oxide Semi-Polar Nonionic Surfactant The amine oxide semi-polar nonionic surfactant of the present invention comprise compounds and mixtures of compounds having the formula: wherein K\ is an alkyl, 2-hydroxyalkyl, or 3-hydroxyalkyl radical in which the alkyl and alkoxy, respectively, contain from about 10 to about 18 carbon atoms; R 2 and R3 are each methyl, ethyl, propyl, isopropyl, or A n wherein A is an ethylene oxide or propylene oxide unit and n is from 1 to about 10. The above amine oxides are more fully described in U.S. Patent 4,316,824 (Pancheri), issued February 23, 1982; U.S. Patent 5,075,501 (Borland et al), issued December 24, 1991; and U.S. Patent 5,071,594, (Borland et al), issued December 10, 1991, all which are incorporated herein by reference. The amine oxide surfactants wherein R 2 or R3 is ethylene oxide or propylene oxide can be produced by a standard oxidation reaction of the corresponding amine. These amines include Ethomeens™ commercially available from Akzo. The present invention contain from about 0.2% to about 20%, preferably from about 0.5% to about 10%, more preferably from about 1% to about 5% by weight of the long chain amine oxide. Preferred amine oxides herein are substantially free of amine and/or nitrosamine ("impurity"). Preferably, the amine oxide comprises less than about 2% free amine, more preferably about 1% or lower; and less than about 500 parts per billion, more preferably less than about 50 parts per billion by weight nitrosamine. Fatty Acid The compositions of the present invention contain from about 1% to about 20%, preferably from about 2% to about 15%, most preferably from about 3% to about 10%, by weight of a fatty acid containing from about 10 to about 22 carbon atoms. The fatty acid can also containing from about 1 to about 10 ethylene oxide units in the hydrocarbon chain. Suitable fatty acids are saturated and or unsaturated and can be obtained from nature sources such as plant or animal esters (e.g., palm kernel oil, palm oil, coconut oil, babassu oil, safflower oil, tall oil, castor oil, tallow and fish oils, grease, and mixtures thereof) or synthetically prepared (e.g., via the oxidation of petroleum or by hydrogenation of carbon monooxide via the Fisher-Tropsch process). Examples of suitable saturated fatty acids for use in the compositions of this invention include capric, lauric, myristic, palmitic, stearic, arachidic and behenic acid. Suitable unsaturated fatty acid species include palmitoleic, oleic, linoleic, linolenic and ricinoleic acid. One class of preferred fatty acids are saturated C10- 14 (coconut) fatty acids, from about 5: 1 to 1: 1 (preferably about 3: 1) weight ratio mixtures of lauric and myristic acid, and mixtures of the above lauric/myristic blends with oleic acid at a weight ratio of about 4:1 to 1:4 mixed lauric/myristic:oleic. Especially preferred fatty acids are saturated Cj fatty acid, saturated Cι 2 -Ci4 fatty acids, and saturated or unsaturated Cj 2 to Ci fatty acids, and mixtures thereof. Preferred compositions herein comprise the amine oxide surfactant and fatty acid in a molar ratio of from about 2: 1 to about 1 :4. Auxiliary Detergent Surfactants The compositions herein preferably also contain from about 1% to about 10%, preferably from about 1.5% to about 5%, of an ethoxylated nonionic surfactant. The weight ratio of synthetic anionic surfactant (on an acid basis) to nonionic surfactant is preferably from about 3:1 to about 20:1, more preferably from about 5:1 to about 15:1. The nonionic surfactant helps ensure the formation and absorption of sufficient hardness surfactant at the air/water interface to provide good greasy/oily soil removal. The ethoxylated nonionic surfactant is of the formula Rl(OC 2 ϊ_4) n OH, where R! is a Cg-Cj6 alkyl group or a Cg-Cι 2 alkyl phenyl group, n is from about 3 to about 9, and said nonionic surfactant has an HLB (Hydrophilic-Lipophilic Balance) of from about 6 to about 14, preferably from about 10 to about 13. These surfactants are more fiilly described in U.S. Patents 4,285,841, Barrat et al., issued August 25, 1981, and 4,284,532, Leikhim et al., issued August 18, 1981, both incorporated herein by reference. Particularly preferred are condensation products of C<)-Cι 2 alcohol with from about 3 to about 8 moles of ethylene oxide per mole of alcohol, e.g., C\ \ alcohol condensed with about 7 moles of ethylene oxide per mole of alcohol. Other surfactants, useful in the present compositions at levels up to about 10% by weight, preferably up to about 5%, include the cosurfactants in U.S. Patent 4,507,219, Hughes, issued March 26, 1985; the alkylpolysaccharides in U.S. Patent 4,565,647, Llenado, issued January 21, 1986; and the polyhydroxy fatty acid amide surfactants in Irish Patent Application 91-3410, published March 28, 1992, all incorporated herein by reference. Water Finally, the compostions herein contain from about 20% to about 55%, preferably from about 30% to about 50% water, by weight of the composition. Optional Components The compositions herein also preferably contain up to about 30%, more preferably from about 1% to about 20%, most preferably from about 1% to about 10%, by weight of a detergent builder material. While all manner of detergent builders known in the art can be used in the present compositions, the type and level of builder should be selected such that the final composition has an initial pH of from about 7.0 to about 9.0 at a concentration of from about 1% to about 10% by weight in water at 20°C. Detergent builders are described in U.S. Patent No. 4,321,165, Smith et al, issued March 23, 1982, incorporated herein by reference. In the preferred liquid detergent compositions herein, the builder preferably represents from about 1% to about 20%, more preferably from abut 3% to about 10%, by weight of the composition. Preferred builders for use in liquid detergents herein are described in U.S. Patent No. 4,284,532, Leikhim et al, issued August 18, 1981, incorporated herein by reference. A particularly preferred builder is citric acid. Enzymes can be included in the formulations herein for a wide variety of fabric laundering purposes, including removal of protein-based, carbohydrate-based, or triglyceride-based stains, for example, and for fabric restoration. The enzymes to be incorporated include proteases, amylases, upases, and cellulases, as well as mixtures thereof. Other types of enzymes may also be included. They may be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin. However, their choice is governed by several factors such as pH-activity and/or stability optima, thermostability, stability versus active detergents, builders and so on. In this respect bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and fungal cellulases. Particularly preferred compositions herein contain from about 0.05% to about 2% by weight of detersive enzymes, especially the amylases, proteases, and mixtures thereof, of the type well known to detergent formulators. Enzymes are normally incorporated at levels sufficient to provide up to about 5 mg by weight, more typically about 0.01 mg to about 3 mg, of active enzyme per gram of the composition. Stated otherwise, the compositions herein will typically comprise from about 0.001% to about 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. Suitable examples of proteases are the subtilisins which are obtained from particular strains of B. subtilis and B. licheniforms. Another suitable protease is obtained from a strain of Bacillus, having maximum activity throughout the pH range of 8-12, developed and sold by Novo Industries A/S under the registered trade name ESPERASE. The preparation of this enzyme and analogous enzymes is described in British Patent Specification No. 1,243,784 of Novo. Proteolytic enzymes suitable for removing protein-based stains that are commercially available include those sold under the tradenames ALCALASE and SAVINASE by Novo Industries A/S (Denmark) and MAXATASE by International Bio-Synthetics, Inc. (The Netherlands). Other proteases include Protease A (see European Patent Application 130,756, published January 9, 1985) and Protease B (see European Patent Application Serial No. 87303761.8, filed April 28, 1987, and European Patent Application 130,756, Bott et al, published January 9, 1985). Amylases include, for example, α-amylases described in British Patent Specification No. 1,296,839 (Novo), RAPEDASE, International Bio-Synthetics, Inc. and TERMAMYL, Novo Industries. The cellulase usable in the present invention include both bacterial or fungal cellulase. Preferably, they will have a pH optimum of between 5 and 9.5. Suitable cellulases are disclosed in U.S. Patent 4,435,307, Barbesgoard et al, issued March 6, 1984, which discloses fungal cellulase produced from Humicola insolens and Humicola strain DSM1800 or a cellulase 212-producing fungus belonging to the genus Aeromonas, and cellulase extracted from the hepatopancreas of a marine mollusk (Dolabella Auricula Solander). Suitable cellulases are also disclosed in GB-A- 2.075.028; GB-A-2.095.275 and DE-OS-2.247.832. CAREZYME (Novo) is especially useful. Suitable lipase enzymes for detergent usage include those produced by microorganisms of the Pseudomonas group, such as Pseudomonas stutzeri ATCC 19.154, as disclosed in British Patent 1,372,034. See also Upases in Japanese Patent Application 53,20487, laid open to public inspection on February 24, 1978. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan, under the trade name Lipase P "Amano," hereinafter referred to as "Amano-P." Other commercial Upases include Amano-CES, Upases ex Chromobacter viscosum, e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and further Chromobacter viscosum Upases from U.S. Biochemical Corp., U.S.A. and Diosynth Co., The Netherlands, and Upases ex Pseudomonas gladioli. The LIPOLASE enzyme derived from Humicola lanuginosa and commercially available from Novo (see also EPO 341,947) is a preferred lipase for use herein. A wide range of enzyme materials and means for their incorporation into synthetic detergent compositions are also disclosed in U.S. Patent 3,553,139, issued January 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S. Patent 4,101,457, Place et al, issued July 18, 1978, and in U.S. Patent 4,507,219, Hughes, issued March 26, 1985, both. Enzyme materials useful for liquid detergent formulations, and their incorporation into such formulations, are disclosed in U.S. Patent 4,261,868, Hora et al, issued April 14, 1981. Enzymes for use in detergents can be stabilized by various techniques. Enzyme stabilization techniques are disclosed and exemplified in U.S. Patent 3,600,319, issued August 17, 1971 to Gedge, et al, and European Patent Application Publication No. 0 199 405, Application No. 86200586.5, published October 29, 1986, Venegas. Enzyme stabilization systems are also described, for example, in U.S. Patent 3,519,570. The enzymes employed herein may be stabilized by the presence of water- soluble sources of calcium and/or magnesium ions in the finished compositions which provide such ions to the enzymes. (Calcium ions are generally somewhat more effective than magnesium ions and are preferred herein if only one type of cation is being used.) Additional stability can be provided by the presence of various other art- disclosed stabilizers, especially borate species. See Severson, U.S. 4,537,706. Typical detergents, especially liquids, will comprise from about 1 to about 30, preferably from about 2 to about 20, more preferably from about 5 to about 15, and most preferably from about 8 to about 12, millimoles of calcium ion per liter of finished composition. This can vary somewhat, depending on the amount of enzyme present and its response to the calcium or magnesium ions. The level of calcium or magnesium ions should be selected so that there is always some minimum level available for the enzyme, after allowing for complexation with builders, fatty acids, etc., in the composition. Any water-soluble calcium or magnesium salt can be used as the source of calcium or magnesium ions, including, but not limited to, calcium chloride, calcium sulfate, calcium malate, calcium maleate, calcium hydroxide, calcium formate, and calcium acetate, and the corresponding magnesium salts. A small amount of calcium ion, generally from about 0.05 to about 0.4 millimoles per liter, is often also present in the composition due to calcium in the enzyme slurry and formula water. In solid detergent compositions the formulation may include a sufficient quantity of a water-soluble calcium ion source to provide such amounts in the laundry liquor. In the alternative, natural water hardness may suffice. It is to be understood that the foregoing levels of calcium and/or magnesium ions are sufficient to provide enzyme stability. More calcium and/or magnesium ions can be added to the compositions to provide an additional measure of grease removal performance. Accordingly, as a general proposition the compositions herein will typically comprise from about 0.05% to about 2% by weight of a water-soluble source of calcium or magnesium ions, or both. The amount can vary, of course, with the amount and type of enzyme employed in the composition. The compositions herein may also optionally, but preferably, contain various additional stabilizers, especially borate-type stabilizers. Typically, such stabilizers will be used at levels in the compositions from about 0.25% to about 10%, preferably from about 0.5% to about 5%, more preferably from about 0.75% to about 4%, by weight of boric acid or other borate compound capable of forming boric acid in the composition (calculated on the basis of boric acid). Boric acid is preferred, although other compounds such as boric oxide, borax and other alkali metal borates (e.g., sodium ortho-, meta- and pyroborate, and sodium pentaborate) are suitable. Substituted boric acids (e.g., phenylboronic acid, butane boronic acid, and p-bromo phenylboronic acid) can also be used in place of boric acid. Other preferred components for use in liquid detergents herein are the neutralizing agents, buffering agents, phase regulants, hydrotropes, polyacids, suds regulants, opacifiers, antioxidants, bactericides, dyes, perfumes, and brighteners described in the U.S. Patent No. 4,285,841, Barrat et al, issued August 25, 1981, incorporated herein by reference. Preferred neutralizing agents for use herein are organic bases, especially triethanolamine and monoethanol amine, which results in better detergency performance than inorganic bases such as sodium and potassium hydroxides. The following non-limiting examples illustrate the compositions of the present invention. All percentages, parts and ratios used herein are by weight unless otherwise specified. EXAMPLE I Heavy duty liquid laundry detergent compositions are prepared by mixing the listed ingredients in the stated proportions in the order shown. Product is cooled to room temperature before addition of the protease enzyme. Composition: A B C D Ingredient .. Λ_ 'eight ' » ... , C12-15alk l polyethoxylate 12.18 12.18 12.18 12.18 (2.25) sulfonic acid C12-15 alkyl sulfonic acid 4.49 4.49 4.49 4.49 C12-14 alkyl dimethyl amine oxide - — 1.00 1.00 Ethanol 3.55 3.55 3.55 3.55 Monoethanolamine 1.20 1.20 1.20 1.20 Propanediol 8.00 8.00 8.00 8.00 Cll Alkyl polyethoxylate (7) 4.17 4.17 4.17 4.17 C12-14 alkyl glucose amide 4.17 4.17 4.17 4.17 Sodium toluene sulfonate 3.00 3.00 3.00 3.00 C12-14 fatty acid — 3.21 — 3.21 Citric acid 1.92 1.92 1.92 1.92 Boric acid 3.50 3.50 3.50 3.50 Sodium hydroxide to > pH 8. 0 Tetraethylenepentamine ethoxylated 1.18 1.18 1.18 1.18 (15-18) Protease enzyme 1.10 1.10 1.10 1.10 Lipase enzyme 0.12 0.12 0.12 0.12 Cellulase enzyme 0.10 0.10 0.10 0.10 Water, perfume and minor ingredients balance The products are evaluated for their cleaning efficacy by testing them side by side in the U.S. washing machines. Artificially stained fabrics (make-up on white cotton fabric and butter stains on blue knit cotton fabric) are used as model soils/stains. Stains are first pretreated by application of one mL of the respective composition and set aside for 5 minutes after which they are washed for 12 minutes in 95°F temperature wash solution in a standard washing machine load. A total of 92 mL of each composition is used in each washer. The test is repeated four times. The cleaned test fabrics are graded visually for any residual soil by a panel of expert graders on a scale of -4 to +4 panel score units (PSU); +4 indicating maximum cleaning adcantage for the product in question. The results are as follows: Panel Score Units (PSU) A B C D Make-up 0.0 -0.4 0.5 1.8s Butter 0.0 -0.1 0.1 0.8s Average 0.0 -0.3 0.3 1.3s "s" indicates statistically significant from zero at 95% confidence interval The results show that composition B is poorer than Composition A by 0.3 PSU. Similarly Compostion C is only slightly better than Composition A (0.3 PSU) However composition D is significantly superior to A, B or D. This confirms that C12-14 fatty acid or C 12- 14 alkyl dimethyl amine oxide (B and C) do not contribute to cleaning. However, the combination of the two (D) provides a significant cleaning benefit. WHAT IS CLAIMED IS:

Claims: 34 PCJ7US95/04735 13 1. An aqueous heavy duty liquid laundry detergent composition characterized in that it comprises, by weight of the composition: (a) from 10% to 40% of an anionic synthetic surfactant; (b) from 0.2% to 20% of an amine oxide semi-polar nonionic surfactant of the formula: wherein R\ is an alkyl, 2-hydroxyalkyl, or 3-hydroxyalkyl radical in which the alkyl and alkoxy, respectively, contain from 10 to 18 carbon atoms; and R 2 and R3 are each methyl, ethyl, propyl, isopropyl, or A n wherein A is an ethylene oxide or propylene oxide unit and n is from 1 to 10; and (c) from 1% to 20% of a fatty acid containing from 10 to 22 carbon atoms; wherein the pH of said composition is between 7 and 9.5 at a concentration of 10% by weight in water at 20°C and wherein the composition is substantially free of alkyl benzene sulfonates. 2. A composition according to Claim 1 wherein the molar ratio of amine oxide surfactant to fatty acid is from 2: 1 to 1 :4. 3. A heavy duty liquid detergent composition according to any of the preceding claims comprising from 15% to 30% of an anionic synthetic surfactant selected from the group consisting of alkyl sulfates containing from 10 to 18 carbon atoms, alkyl ethoxy sulfates containing from 10 to 18 carbon atoms and an average of up to 4 ethylene oxide units per mole of alkyl sulfate, and mixtures thereof. 4. A heavy duty Uquid detergent composition according to any of the preceding claims which further comprises from 1% to 10% by weight of an ethoxylated nonionic surfactant of the formula R 1 (OC 2 H4) n OH, wherein R 1 is a C10-C16 alkyl group or a Cg-Cι alkyl phenyl group, n is from 3 to 9, and said nonionic surfactant has an HLB (Hydrophilic-Lipophilic Balance) of from 6 to 14. 5. A heavy duty liquid detergent composition according to any of the preceding claims comprising from 1.5% to 5% of an ethoxylated nonionic surfactant which is a condensation product of C9-Cι 2 alcohol with from 3 to 8 moles of ethylene oxide per mole of alcohol. 6. A composition according to any of the preceding claims comprising from 3% to 10% fatty acid. 7. A composition according to any of the preceding claims wherein the fatty acid is selected from the group consisting of saturated Cι 2 fatty acid, saturated Cι 2 -Ci4 fatty acids, and saturated or unsaturated Cι to Cjg fatty acids, and mixtures thereof. 8. A composition according to any of the preceding claims wherein Ri is Cio- Ci g alkyl and R 2 and R3 are methyl. 9. A composition according to any of the preceding claims comprising from 1% to 5% of the amine oxide surfactant.

Inventors: MORELLI JOSEPH PAUL, PANANDIKER RAJAN KESHAV, MORELLI, JOSEPH, PAUL, PANANDIKER, RAJAN, KESHAV
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1995
Main classification: C11D10
IPC codes: C11D1, C11D3, C11D10