High Foaming Nonionic Surfactant Based Liquid Detergent

The present invention relates to novel light duty liquid detergent compositions with high foaming properties, containing a nonionic surfactant, a specific group of anionic surfactants and a Zwitterionic betaine surfactant, wherein the surfactants are dissolved in an aqueous medium.

Nonionic surfactants are in general chemically inert and stable toward pH change and are therefore well suited for mixing and formulation with other materials. The superior performance of nonionic surfactants on the removal of oily soil is well recognized. Nonionic surfactants are also known to be mild to human skin. However, as a class, nonionic surfactants are known to be low or moderate foamers. Consequently, for detergents which require copious and stable foam, the application of nonionic surfactants is limited. There have been substantial interest and efforts to develop a high foaming detergent with nonionic surfactants as the major ingredient. Little has been achieved.

The prior art is replete with light duty liquid detergent compositions containing nonionic surfactants in combination with anionic and/or betaine surfactants wherein the nonionic detergent is not the major active surfactant, as shown in U.S. Pat. No. 3,658,985 wherein an anionic based shampoo contains a minor amount of a fatty acid alkanolamide. U.S. Pat. No. 3,769,398 discloses a betaine-based shampoo containing minor amounts of nonionic surfactants. This patent states that the low foaming properties of nonionic detergents renders its use in shampoo compositions non-preferred. U.S. Pat. No. 4,329,335 also discloses a shampoo containing a betaine surfactant as the major ingredient and minor amounts of a nonionic surfactant and of a fatty acid mono- or di-ethanolamide. U.S. Pat. No. 4,259,204 discloses a shampoo comprising 0.8-20% by weight of an anionic phosphoric acid ester and one additional surfactant which may be either anionic, amphoteric, or nonionic. U.S. Pat. No. 4,329,334 discloses an anionicamphoteric based shampoo containing a major amount of anionic surfactant and lesser amounts of a betaine and nonionic surfactants.

U.S. Pat. No. 3,935,129 discloses a liquid cleaning composition based on the alkali metal silicate content and containing five basic ingredients, namely, urea, glycerin, triethanolamine, an anionic detergent and a nonionic detergent. The silicate content determines the amount of anionic and/or nonionic detergent in the liquid cleaning composition. However, the foaming property of these detergent compositions is not discussed therein.

U.S. Pat. No. 4,129,515 discloses a heavy duty liquid detergent for laundering fabrics comprising a mixture of substantially equal amounts of anionic and nonionic surfactants, alkanolamines and magnesium salts, and, optionally, zwitterionic surfactants as suds modifiers.

U.S. Pat. No. 4,224,195 discloses an aqueous detergent composition for laundering socks or stockings comprising a specific group of nonionic detergents, namely, an ethylene oxide of a secondary alcohol, a specific group of anionic detergents, namely, a sulfuric ester salt of an ethylene oxide adduct of a secondary alcohol, and an amphoteric surfactant which may be a betaine, wherein either the anionic or nonionic surfactant may be the major ingredient.

The prior art also discloses detergent compositions containing all nonionic surfactants as shown in U.S. Pat. Nos. 4,154,706 and 4,329,336 wherein the shampoo compositions contain a plurality of particular nonionic surfactants in order to effect desirable foaming and detersive properties despite the fact that nonionic surfactants are usually deficient in such properties.

U.S. Pat. No. 4,013,787 discloses a piperazine based polymer in conditioning and shampoo compositions which may contain all nonionic surfactant or all anionic surfactant.

U.S. Pat. No. 4,450,091 discloses high viscosity shampoo compositions containing a blend of an amphoteric betaine surfactant, a polyoxybutylene polyoxyethylene nonionic detergent, an anionic surfactant, a fatty acid alkanolamide and a polyoxyalkylene glycol fatty ester.

U.S. Pat. No. 4,595,526 describes a composition comprising a nonionic surfactant, a betaine surfactant, an anionic surfactant and a C.sub.12 -C.sub.14 fatty acid monoethanolamide foam stabilizer.

However, none of the above-cited patents discloses a high foaming, nonionic based, liquid detergent composition containing a nonionic surfactant, an anionic surfactant excluding an esterfied polyethoxyether surfactant and a foaming zwitterionic surfactant selected from betaine type surfactants, wherein the composition does not contain any amine oxide, calcium carbonate, polymeric or clay thickeners, abrasive, clays, silicas, alkanol amides, (for example cocodiethanol amide), alkyl glycine surfactant, cyclic imidinium surfactant, or more than 3.0 wt. % of a fatty acid or a metal salt of the fatty acid compounds.

It has now been found that a high foaming liquid detergent can be formulated with a nonionic surfactant which has desirable cleaning properties, mildness to the human skin.

Another object of this invention is to provide novel, liquid aqueous detergent compositions containing a nonionic surfactant, an anionic surfactant, and a zwitterionic betaine surfactant, wherein the composition does not contain amine oxide, a fatty acid alkanolamide foam stabilizer, an alkali metal carbonate, polymeric or clay thickeners, clays, abrasives, alkyl glycine surfactants, cyclic imidinium surfactants, silicas or more than 3 wt. % of a fatty acid or a metal salt of a fatty acid.

Still another object of this invention is to provide a novel, liquid detergent with desirable high foaming and cleaning properties which is mild to the human skin.

Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein the novel, high foaming, light duty liquid detergent of this invention comprises three essential surfactants: a water soluble, ethoxylated, nonionic surfactant as the major active ingredient in an amount exceeding 50% by weight of the total surfactant content; a supplemental amount of a foaming anionic surfactant and a foaming water soluble, zwitterionic surfactant selected from the class of betaines, wherein the surfactants are dissolved in an aqueous vehicle and the composition does not contain any amine oxide, fatty acid alkanol amide foam stabilizer, anionic alkyl ether polyethenoxy sulfate detergent, alkali metal carbonate, polymeric or clay thickeners, clays, abrasives, silicas, alkyl glycine surfactant, cyclic imidinium surfactant, or more than 3 wt. % a fatty acid or a metal salt of the fatty acid.

More specifically, the present invention relates to a high foaming, nonionic based, liquid detergent comprising: a nonionic surfactant selected from the group consisting of water soluble primary aliphatic alcohol ethoxylates secondary aliphatic alcohol ethoxylates, alkyl phenol ethoxylates and alcohol ethylene oxide propylene oxide condensates; supplementary amounts of an anionic surfactant selected from the group consisting of water soluble salts of C8-C18 alkyl sulfates, C8-C16 benzene sulfonates, C10-C20 paraffin sulfonates, alpha C10-C24 olefin sulfonates, C8-C18 alkyl sulfoacetates, C8-C18 alkyl sulfosuccinate esters, C8-C18 acyl isethionates and C8-C18 acyl taurates and a water soluble zwitterionic betaine surfactant, wherein the surfactants are dissolved in an aqueous vehicle.

The total amount of surfactants may constitute about 10%-55%, preferably about 20%-40%, most preferably 25%-35%, by weight of the liquid composition.

The high foaming nonionic based light duty liquid detergent compositions of the instant invention comprise approximately by weight: 10 to 30 wt. % of a water soluble nonionic surfactant; 1 to 12 wt. % of a water soluble or dispersible anionic surfactant; 0.5 to 10.0 wt. % of a betaine surfactant; and 44 to 87 wt. % of water, wherein the compositions do not contain any amine oxides, fatty acid alkanol amides, (for example--cocodiethanolamide), calcium carbonate, polymeric or clay thickeners, abrasives, clays, silicas, alkyl glycine surfactants, cyclic imidinium surfactants, or more than 3 wt. % of a fatty acid or a metal salt of the fatty acid.

The nonionic surfactant which constitutes the major ingredient in the liquid detergent composition is present in amounts of about 10 to 30%, preferably 13 to 25%, most preferably 16 to 22%, by weight of the composition and provides superior performance in the removal of oily soil and mildness to human skin.

The water soluble nonionic surfactants utilized in this invention are commercially well known and include the primary aliphatic alcohol ethoxylates, secondary aliphatic alcohol ethoxylates, alkylphenol ethoxylates and ethylene-oxide-propylene oxide condensates on primary alkanols, such a Plurafacs (BASF) and condensates of ethylene oxide with sorbitan fatty acid esters such as the Tweens (ICI). The nonionic synthetic organic detergents generally are the condensation products of an organic aliphatic or alkyl aromatic hydrophobic compound and hydrophilic ethylene oxide groups. Practically any hydrophobic compound having a carboxy, hydroxy, amido, or amino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide or with the polyhydration product thereof, polyethylene glycol, to form a water soluble nonionic detergent. Further, the length of the polyethenoxy hydrophobic and hydrophilic elements.

The nonionic detergent class includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 18 carbon atoms in a straight or branched chain configuration) condensed with about 5 to 30 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 16 moles of ethylene oxide (EO), tridecanol condensed with about 6 to moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.

A preferred group of the foregoing nonionic surfactants are the Neodol ethoxylates (Shell Co.), which are higher aliphatic, primary alcohol containing about 9-15 carbon atoms, such as C.sub.9 -C.sub.11 alkanol condensed with 8 moles of ethylene oxide (Neodol 91-8), C.sub.12-13 alkanol condensed with 6.5 moles ethylene oxide (Neodol 23-6.5), C.sub.12-15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C.sub.14-15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like. Such ethoxamers have an HLB (hydrophobic lipophilic balance) value of about 8 to 15 and give good emulsification, whereas ethoxamers with HLB values below 8 contain less than 5 ethyleneoxide groups and tend to be poor. emulsifiers and poor detergents.

Additional satisfactory water soluble alcohol ethylene oxide condensates are the condensation products of a secondary aliphatic alcohol containing 8 to 18 carbon atoms in a straight or branched chain configuration condensed with 5 to 30 moles of ethylene oxide. Examples of commercially available nonionic detergents of the foregoing type are C.sub.11 -C.sub.15 secondary alkanol condensed with either 9 EO (Tergitol 15-S-9) or 12 EO (Tergitol 15-S-12) marketed by Union Carbide.

Other suitable nonionic detergents include the polyethylene oxide condensates of one mole of alkyl phenol containing from about 8 to 18 carbon atoms in a straight--or branched chain alkyl group with about 5 to 30 moles of ethylene oxide. Specific examples of alkyl phenol ethoxylates include nonyl condensed with about 9.5 moles Of EO per mole of nonyl phenol, dinonyl phenol condensed with about 12 moles of EO per mole of phenol, dinonyl phenol condensed with about 15 moles of EO per mole of phenol and di-isoctylphenol condensed with about 15 moles of EO per mole of phenol. Commercially available nonionic surfactants of this type include Igepal CO-630 (nonyl phenol ethoxylate) marketed by GAF Corporation.

Condensates of 2 to 30 moles of ethylene oxide with sorbitan mono- and tri-C.sub.10 -C.sub.20 alkanoic acid esters having a HLB of 8 to 15 also may be employed as the nonionic detergent ingredient in the described shampoo. These surfactants are well known and are available from Imperial Chemical Industries under the Tween trade name. Suitable surfactants include polyoxyethylene (4) sorbitan monolaurate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (20) sorbitan trioleate and polyoxyethylene (20) sorbitan tristearate.

The anionic surfactant, used in the liquid detergent composition, constitutes about 1% to 12%, preferably 1% to 10%, most preferably 1 to 9%, by weight thereof and provides good foaming properties. However, preferably reduced amounts are utilized in order to enhance the mildness of the skin property desired in the inventive compositions.

The anionic surfactant which may be used in the nonionic based liquid detergent of the invention are water soluble such as triethanolamine salt and include the sodium, potassium, ammonium and ethanalommonium salts of C.sub.8-18 alkyl sulfates such as lauryl sulfate, myristyl sulfate and the like; linear C.sub.8 -C.sub.16 alkyl benzene sulfonates; C.sub.10 -C.sub.20 paraffin sulfonates; alpha olefin sulfonates containing about 10-24 carbon atoms; C.sub.8 -C.sub.18 alkyl sulfoacetates; C.sub.8 -C.sub.18 alkyl sulfosuccinate esters; C.sub.8 -C.sub.18 acyl isethionates; and C.sub.8 -C.sub.18 acyl taurates. Preferred anionic surfactants are the water soluble C.sub.12 -C.sub.16 alkyl sulfates, the C.sub.10 -C.sub.15 alkylbenzene sulfonates, the C.sub.12 -C.sub.17 paraffin sulfonates and the alpha C.sub.12 -C.sub.18 olefin sulfonates.

The paraffin sulfonates may be monosulfonates or di-sulfonates and usually are mixtures thereof, obtained by sulfonating paraffins of 10 to 20 carbon atoms. Preferred paraffin sulfonates are those of C.sub.12-18 carbon atoms chains, and more preferably they are of C.sub.14-17 chains. Paraffin sulfonates that have the sulfonate group(s) distributed along the paraffin chain are described in U.S. Pat. Nos. 2,503,280; 2,507,088; 3,260,744; and 3,372,188; and also in German Patent 735,096. Such compounds may be made to specifications and desirably the content of paraffin sulfonates outside the C.sub.14-17 range will be minor and will be minimized, as will be any contents of di- or poly-sulfonates.

Examples of suitable other sulfonated anionic detergents are the well known higher alkyl mononuclear aromatic sulfonates, such as the higher alkylbenzene sulfonates containing 9 to 18 or preferably 9 or 10 to 15 or 16 carbon atoms in the higher alkyl group in a straight or branched chain, or C.sub.8-15 alkyl toulene sulfonates. A preferred alkylbenzene sulfonate is a linear alkylbenzene sulfonate having a higher content of 3-phenyl (or higher) isomers and a correspondingly lower content (well below 50%) of 2-phenyl (or lower) isomers, such as those sulfonates wherein the benzene ring is attached mostly at the 3 or higher (for example 4, 5, 6 or 7) position of the alkyl group and the content of the isomers in which the benzene ring is attached in the 2 or 1 position is correspondingly low. Preferred materials are set forth in U.S. Pat. No. 3,320,174, especially those in which the alkyls are of 10 to 13 carbon atoms.

The water-soluble zwitterionic surfactant, which is also an essential ingredient of present liquid detergent composition, constitutes about 0.5 to 10%, preferably 2 to 9%, most preferably 7 to 8%, by weight and provides good foaming properties and mildness to the present nonionic based liquid detergent. The zwitterionic surfactant is a water soluble betaine having the general formula: ##STR1## wherein R.sub.1 is an alkyl group having 10 to about 20 carbon atoms, preferably 12 to 16 carbon atoms, or the amido radical: ##STR2## wherein R is an alkyl group having about 9 to 19 carbon atoms and a is the integer 1 to 4; R.sub.2 and R.sub.3 are each alkyl groups having 1 to 3 carbons and preferably 1 carbon; R.sub.4 is an alkylene or hydroxyalkylene group having from 1 to 4 carbon atoms and, optionally, one hydroxyl group. Typical alkyldimethyl betaines include decyl dimethyl betaine or 2-(N-decyl-N, N-dimethyl-ammonia) acetate, coco dimethyl betaine or 2-(N-coco N, N-dimethylammonio) acetate, myristyl dimethyl betaine, palmityl dimethyl betaine, lauryl dimethyl betaine, cetyl dimethyl betaine, stearyl dimethyl betaine, etc. The amidobetaines similarly include cocoamidoethylbetaine, cocoamidopropyl betaine and the like. A preferred betaine is coco (C.sub.8 -C.sub.18) amidopropyl dimethyl betaine.

All of the aforesaid ingredients in this light duty liquid detergent are water soluble or water dispersible and remain so during storage.

This particular combination of anionic sulfate surfactant, and betaine surfactant, provides a detergent system which coacts with the nonionic surfactant to product a liquid detergent composition with desirable foaming, foam stability and detersive properties. Surprisingly, the resultant homogeneous liquid detergent exhibits the same or better foam performance, both as to initial foam volume and stability of foam in the presence of soils, and cleaning efficacy as an anionic based light duty liquid detergent (LDLD) as shown in the following Examples.

The essential ingredients discussed above are solubilized in an aqueous medium comprising water and optionally, solubilizing ingredients such as alcohols and dihydroxy alcohols such as C2-C3 mono- and di-hydoroxy alkanols, e.g. ethanol, isopropanol and propylene glycol. Suitable water soluble hydrotropic salts include sodium, potassium, ammonium and mono-, di- and triethanolammonium salts. While the aqueous medium is primarily water, preferably said solubilizing agents are included in order to control the viscosity of the liquid composition and to control low temperature cloud clear properties. Usually, it is desirable to maintain clarity to a temperature in the range of 5.degree. C. to 10.degree. C. Therefore, the proportion of solubilizer generally will be from about 1% to 15%, preferably 2% to 12%, most preferably 3% to 8%, by weight of the detergent composition with the proportion of ethanol, when present, being 5% of weight or less in order to provide a composition having a flash point above about 46.degree. C. Preferably the solubilizing ingredient will be a mixture of ethanol and either sodium xylene sulfonate or sodium cumene sulfonate or a mixture of said sulfonates. Another extremely effective solubilizing or cosolubilizing agent used at a concentration of about 0.1 to 5 wt. percent, more preferably about 0.5 to 4.0 weight percent is isethionic acid or an alkali metal salt of isethionic acid having the formula:

wherein X is hydrogen or an alkali metal cation, preferably sodium.

In addition to the previously mentioned essential and optional constituents of the light duty liquid detergent, one may also employ normal and conventional adjuvants, provided they do not adversely affect the properties of the detergent. Thus, there may be used various coloring agents and perfumes; ultraviolet light absorbers such as the Uvinuls, which are products of GAF Corporation; sequestering agents such as ethylene diamine tetraacetates; magnesium sulfate heptahydrate; pearlescing agents and opacifiers; pH modifiers; etc. The proportion of such adjuvant materials, in total will normally not exceed 15% of weight of the detergent composition, and the percentages of most of such individual components will be about 0.1% to 5% by weight and preferably less than about 2% by weight. Sodium formate can be included in the formula as a perservative at a concentration of 0.1 to 4.0%. Sodium bisulfite can be used as a color stabilizer at a concentration of about 0.01 to 0.2 wt. %. Typical perservatives are dibromodicyano-butane, citric acid, benzylic alcohol and poly (hexamethylene-biguamide) hydrochloride and mixtures thereof.

The instant compositions can contain about 0.1 to about 4 wt. %, more preferably about 0.5 to 3.0 wt. % of an alkyl polysaccharide surfactant. The alkyl polysaccharides surfactants, which are used in conjunction with the aforementioned surfactant have a hydrophobic group containing from about 8 to about 20 carbon atoms, preferably from about 10 to about 16 carbon atoms, most preferably from about 12 to about 14 carbon atoms, and polysaccharide hydrophilic group containing from about 1.5 to about 10, preferably from about 1.5 to about 4, most preferably from about 1.6 to about 2.7 saccharide units (e.g., galactoside, glucoside, fructoside, glucosyl, fructosyl; and/or galactosyl units). Mixtures of saccharide moieties may be used in the alkyl polysaccharide surfactants. The number x indicates the number of saccharide units in a particular alkyl polysaccharide surfactant. For a particular alkyl polysaccharide molecule x can only assume integral values. In any physical sample of alkyl polysaccharide surfactants there will be in general molecules having different x values. The physical sample can be characterized by the average value of x and this average value can assume non-integral values. In this specification the values of x are to be understood to be average values. The hydrophobic group (R) can be attached at the 2-, 3-, or 4- positions rather than at the 1-position, (thus giving e.g. a glucosyl or galactosyl as opposed to a glucoside or galactoside). However, attachment through the 1- position, i.e., glucosides, galactoside, fructosides, etc., is preferred. In the preferred product the additional saccharide units are predominately attached to the previous saccharide unit's 2-position. Attachment through the 3-, 4-, and 6- positions can also occur. Optionally and less desirably there can be a polyalkoxide chain joining the hydrophobic moiety (R) and the polysaccharide chain. The preferred alkoxide moiety is ethoxide.

Typical hydrophobic groups include alkyl groups, either saturated or unsaturated, branched or unbranched containing from about 8 to about 20, preferably from about 10 to about 18 carbon atoms. Preferably, the alkyl group is a straight chain saturated alkyl group. The alkyl group can contain up to 3 hydroxy groups and/or the polyalkoxide chain can contain up to about 30, preferably less than about 10, alkoxide moieties.

Suitable alkyl polysaccharides are decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl, di-, tri-, tetra-, penta-, and hexaglucosides, galactosides, lactosides, fructosides, fructosyls, lactosyls, glucosyls and/or galactosyls and mixtures thereof.

The alkyl monosaccharides are relatively less soluble in water than the higher alkyl polysaccharides. When used in admixture with alkyl polysaccharides, the alkyl monosaccharides are solubilized to some extent. The use of alkyl monosaccharides in admixture with alkyl polysaccharides is a preferred mode of carrying out the invention. Suitable mixtures include coconut alkyl, di-, tri-, tetra-, and pentaglucosides and tallow alkyl tetra, penta-, and hexaglucosides.

The preferred alkyl polysaccharides are alkyl polyglucosides having the formula

wherein Z is derived from glucose, R is a hydrophobic group selected from the group consisting of alkyl, alkylphenyl, hydroxyalkylphenyl, and mixtures thereof in which said alkyl groups contain from about 10 to about 18, preferably from about 12 to about 14 carbon atoms; n is 2 or 3 preferably 2, r is from 0 to 10, preferable 0; and x is from 1.5 to 8, preferably from 1.5 to 4, most preferably from 1.6 to 2.7. To prepare these compounds a long chain alcohol (R.sub.2 OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (R.sub.1 OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (C.sub.1-6) is reacted with glucose or a polyglucoside (x=2 to 4) to yield a short chain alkyl glucoside (x=1 to 4) which can in turn be reacted with a longer chain alcohol (R.sub.2 OH) to displace the short chain alcohol and obtain the desired alkyl polyglucoside. If this two step procedure is used, the short chain alkylglucosde content of the final alkyl polyglucoside material should be less than 50%, preferably less than 10%, more preferably less than about 5%, most preferably 0% of the alkyl polyglucoside.

The amount of unreacted alcohol (the free fatty alcohol content) in the desired alkyl polysaccharide surfactant is preferably less than about 2%, more preferably less than about 0.5% by weight of the total of the alkyl polysaccharide. For some uses it is desirable to have the alkyl monosaccharide content less than about 10%.

The used herein, "alkyl polysaccharide surfactant" is intended to represent both the preferred glucose and galactose derived surfactants and the less preferred alkyl polysaccharide surfactants. Throughout this specification, "alkyl polyglucoside" is used to include alkyl polyglycosides because the stereochemistry of the saccharide moiety is changed during the preparation reaction.

An especially preferred APG glycoside surfactant is APG 625 glycoside manufactured by the Henkel Corporation of Ambler, PA. APG25 is a nonionic alkyl polyglycoside characterized by the formula:

wherein n=10 (2%); n=122 (65%); n=14 (21-28%); n=16 (4-8%) and n=18 (0.5%) and x (degree of polymerization)=1.6. APG 625 has: a pH of 6 to 10 (10% of APG 625 in distilled water); a specific gravity at 25.degree. C. of 1.1 g/ml; a density at 25.degree. C. of 9.1 lbs/gallon; a calculated HLB of 12.1 and a Brookfield viscosity at 35.degree. C., 21 spindle, 5-10 RPM of 3,000 to 7,000 cps.

The instant compositions can contain a silk derivatives as part of the composition and generally constitute about 0.01 to 3.0% by weight, preferably about 0.1 to 3.0% by weight, most preferably 0.2 to 2.5% by weight of the liquid detergent composition.

Included among the silk derivatives are silk fibers and hydrolyzate of silk fibers. The silk fibers may be used in the form of powder in preparing the liquid detergent or as a powder of a product obtained by washing and treating the silk fibers with an acid. Preferably, silk fibers are used as a product obtained by hydrolysis with an acid, alkali or enzyme, as disclosed in Yoshiaki Abe et al., U.S. Pat. No. 4,839,168; Taichi Watanube et al., U.S. Pat. No. 5,009,813; and Marvin E. Goldberg, U.S. Pat. No. 5,069,898, each incorporated herein by reference.

Another silk derivative which may be employed in the composition of the present invention is protein obtained from degumming raw silk, as disclosed, for example, in Udo Hoppe et al., U.S. Pat. No. 4,839,165, incorporated herein by reference. The principal protein obtained from the raw silk is sericin which has an empirical formula of C.sub.15 H.sub.25 O.sub.3 N.sub.5 and a molecular weight of 323.5.

Another example of a silk derivative for use in the liquid detergent composition of the present invention is a fine powder of silk fibroin in nonfibrous or particulate form, as disclosed in Kiyoshi Otoi et al., U.S. Pat. No. 4,233,212, incorporated herein by reference.

The fine powder is produced by dissolving a degummed silk material in at least one solvent selected from, for example, an aqueous cupriethylene diamine solution, an aqueous ammoniacal solution of cupric hydroxide, an aqueous alkaline solution of cupric hydroxide and glycerol, an aqueous lithium bromide solution, an aqueous solution of the chloride, nitrate or thiocyanate of calcium, magnesium or zinc and an aqueous sodium thiocyanate solution. The resulting fibroin solution is then dialyzed. The dialyzed aqueous silk fibroin solution, having a silk fibroin concentration of from about 3 to 20% by weight, is subjected to at least one treatment for coagulating and precipitating the silk fibroin, such as, for example, by the addition of a coagulating salt, by aeration, by coagulation at the isoelectric point, by exposure to ultrasonic waves, by agitation at high shear rate and the like.

The resulting product is a silk fibroin gel which may be incorporated directly into the liquid detergent composition or the same may be dehydrated and dried into a powder and then dissolved in the liquid detergent composition.

The silk material which may be used to form the silk fibroin includes cocoons, raw silk, waste cocoons, raw silk waste, silk fabric waste and the like. The silk material is degummed or freed from sericin by a conventional procedure such as, for example, by washing in warm water containing a surfact-active agent or an enzyme, and then dried. The degummed material is dissolved in the solvent and preheated to a temperature of from 60.degree. to 95.degree. C., preferably 70.degree. to 85.degree. C. Further details of the process of obtaining the silk fibroin are discussed in U.S. Pat. No. 4,233,212.

A preferred silk derivative is a mixture of two or more individual amino acids which naturally occur in silk. .The principal silk amino acids are glycine, alanine, serine and tyrosine.

A silk amino acid mixture resulting from the hydrolysis of silk of low molecular weight and having a specific gravity of at least 1 is produced by Croda, Inc. and sold under the trade name "CROSILK LIQUID" which typically has a solids content in the range of about 27 to 31% by weight. Further details of the silk amino acid mixture can be found in Wendy W. Kim et al., U.S. Pat. No. 4,906,460, incorporated herein by reference. A typical amino acid composition of "CROSILK LIQUID" is shown in the following Table.

The instant compositions can contain a viscosity modifying solvent at a concentration of about 0.1 to 5.0 weight percent, more preferably about 0.5 to 4.0 weight percent. The viscosity modifying agent is an alcohol of the formula ##STR3## wherein R.sub.1 =CH.sub.3, CH.sub.2 CH.sub.3 R.sub.2 =CH.sub.3, CH.sub.2 CH.sub.3

R.sub.3 =CH.sub.2 OH, CH.sub.2 CH.sub.2 OH;

which is preferably 3-methyl-3-methoxy-butanol.

The 3-methyl-3-methoxy butanol is commercially available from Sattva Chemical Company of Stamford, Connecticut and Kuraray Co., Ltd., Osaka, Japan.

The instant composition can contain about 0.1 to 4.0% of a protein selected from the group consisting of hydrolyzed animal collagen protein obtained by an enzymatic hydrolysis, lexeine protein, vegetal protein and hydrolyzed wheat protein and mixtures thereof.

The present nonionic based light duty liquid detergents such as dishwashing liquids are readily made by simple mixing methods from readily available components which, on storage, do not adversely affect the entire composition. However, it is preferred that the nonionic surfactant be mixed with the solubilizing ingredients, e.g., ethanol and, if present, prior to the addition of the water to prevent possible gelation. The nonionic based surfactant system is prepared by sequentially adding with agitation the anionic surfactant and the betaine to the non-ionic surfactant which has been previously mixed with a solubilizing agent such as ethyl alcohol and/or sodium xylene sulfonate to assist in solubilizing said surfactants, and then adding with agitation the formula amount of water to form an aqueous solution of the nonionic based surfactant system. The use of mild heating (up to 100.degree. C.) assists in the solubilization of the surfactants. The viscosities are adjustable by changing the total percentage of active ingredients. No polymeric or clay thickening agent is added. In all such cases the product made will be pourable from a relatively narrow mouth bottle (1.5 cm. diameter) or opening, and the viscosity of the detergent formulation will not be so low as to be like water. The viscosity of the detergent desirably will be at least 100 centipoises (cps) at room temperature, but may be up to about 1,000 centipoises as measured with a Brookfield Viscometer using a number 2 spindle rotating at 30 rpm. Its viscosity may approximate those of commercially acceptable detergents now on the market. The detergent viscosity and the detergent itself remain stable on storage for lengthy periods of time, without color changes or settling out of any insoluble materials. The pH of this formation is substantially neutral to skin, e.g., about 4.5 to 8 and preferably about 5.5 to about 5.0.

The compositions of the instant invention are optically clear that is they exhibit a light transmission of at least 95%, more preferably at least 98%.

These products have unexpectedly desirable properties. For example, the foam quality and detersive property is equal to or better than standard light duty liquid detergents while using a nonionic surfactant as the primary surfactant and minimal amounts of anionic surfactant, thereby achieving a mild, non-irritating liquid detergent.

The following examples are merely illustrative of the invention and are not to be construed as limiting thereof.

Formula A of Example 1 (composition of U.S. Pat. No. 4,595,526) and Formula B were compared in a Hand Dish Wash Test. The test was run with both Tagu Spaghetti Sauce and Shell Soil. The results show that dish washing grformance between the U.S. formula and the European formula is similar. The test was run blink with each trial consisting of three runs of each product and was done in both 300 and 150 rpm water hardness.