US3574122A - Liquid detergent compositions - Google Patents

Abstract

A PHASE-STABLE, HEAVY-DUTY, LIQUID DETERGENT EMULSION COMPOSITION COMPRISING A SYNTHETIC ORGANIC NONIONIC DETERGENT AND TRISODIUM NITRILOTRIACETATE IN AN AQUEOUS MEDIUM CONTAINING A TERNARY EMULSION STABILIZER SYSTEM WHICH IS A FIRST STABILIZER COMBINATION OF A HYDROLYZED LINEAR COPOLYMER OF ETHYLENE AND MALEIC ANHYDRIDE PLUS A HYDROLYZED CROSS-LINKED COPOLYMER OF ETHYLENE AND MALEIC ANHYDRIDE, A SECOND STABILIZER WHICH IS A HYDROTYPE AND A THIRD STABILIZER WHICH IS AN ELECTROLYTE.

Description

United States Patent 3,574,122 LIQUID DETERGENT COMPOSITIONS Thomas Aquinas Payne, Jr., Teaneck, and Warren Eric Olson, Verona, N.J., and Samuel Hirsch C0hcn,, Bronx, N.Y., assignors to Lever Brothers Company, New York,

No Drawing. Filed Aug. 18, 1967, Ser. No. 661,522

Int. Cl. Clld 1/12, 3/066 US. Cl. 252-137 5 Claims ABSTRACT OF THE DISCLGSURE A phase-stable, heavy-duty, liquid detergent emulsion composition comprising a synthetic organic nonionic detergent and trisodium nitrilotriacetate in'an aqueous medium containing a ternary emulsion stabilizer system which is a first stabilizer combination of a hydrolyzed linear copolymer of ethylene and maleic anhydride plus a hydrolyzed cross-linked copolymer of ethylene and maleic anhydride, a second stabilizer which is a hydrotrope and a third stabilizer which is an electrolyte.

The present invention relates to phase-stable, heavyduty liquid detergent emulsion compositions.

The public has shown considerable acceptance of liquid detergent formulations because of their convenient handling and measuring and because of their non-dusting characteristics. Unfortunately, when formulating liquid, heavy-duty detergents containing a non-ionic detergent active, it is difiicult to achieve homogeneity because of the salting out effect of the added builder material, e.g., sodium or potassium pyrophosphate. In the past this salting out efiect has been solved to a great extent by the inclusion of binary stabilizer mixtures containing (a) various resins (see co-pending US. patent application Ser. No. 362,489, filed Apr. 24, 1964, and now abandoned) and (b) small amounts of an organic hydrotrope such as sodium xylene sulfonate, sodium toluene, sulfonate and the like. The binary stabilizer systems of the prior art which are effective when using inorganic builders, such as the pyrophosphates, have been found unsuitable in producing stable homogenous liquid detergents containing trisodium nitrilotriacetate (an organic sequestrant) in place of most or all of the inorganic builders. To illustrate, if a liquid detergent containing all of the ingredients set forth in the above-mentioned co-pending US. patent application are used with the exception that 25% trisodium nitrilotriacetate is substituted in place of an equal amount of tetrapotassium pyrophosphate, a liquid is formed which readily separates into two phases upon standing or upon testing by the accelerated phase-stability test as set forth hereinafter. Homogenization of such mixtures does not alter the above result.

It is, therefore, an object of the present invention to provide heavy-duty liquid detergent emulsion compositions containing a nonionic organic detergent and trisodium nitrilotriacetate as an organic sequestrant builder, which emulsion will have phase stability. Another object is to provide phase-stable, heavy-duty liquid detergent emulsion compositions which are free from or substantially free from phosphate builders. A further object of the invention is to provide phase-stable, heavy duty liquid 3,574,122 Patented Apr. 6, 1971 detergent emulsion compositions having improved detergency not only in hot water, but also in cold water. Other objects of the invention include the provision of phase-stable, heavy-duty liquid detergent emulsion compositions which have improved mildness and lower toxicity, which are readily prepared and which can be produced as a reasonable cost.

The above objects and advantages of the present invention are obtained by the provision of a phase-stable, heavyduty liquid detergent emulsion composition which contains water as the dispersion medium, a nonionic organic detergent as the active detergent component, trisodium nitrolotriacetate as an organic sequestrant builder and a ternary stabilizer system for maintaining the 'phase stability of the emulsion. The emulsion compositions of the invention further contemplate the inclusion therein of various compatible adjuvants.

As noted above, water serves as the continuous phase or dispersion medium for the emulsion compositions. The amount of water present in the composition varies depending upon the concentration desired and hence water will comprise the substantial balance of the compositions. In general, water will be present in the order of from about 40% to about 60%, and usually from about 45% to about 55% by weight of the composition.

The synthetic organic nonionic detergent or mixtures thereof serve as the detergent active material of the composition and are generally present therein in an amount from about 6% to 15% by weight, and more usually are present in an amount from about 8% to about 10% by weight. The synthetic organic nonionic detergents are the well known polyoxyalkylene compounds which are formed by condensing several moles of an alkylene oxide, such as ethylene oxide or propylene oxide, with a hydrophobic base, such as alkyl phenols, long-chain aliphatic alcohols and mercaptans, propylene oxide-propylene glycol condensates, etc. Representative examples of suitable nonionic detergents are listed in the following tabulation:

Average ethylene oxide content, Trade name I-Iydrophobe moles Sterox DJ Dodecylphcnol 10 Sterox MJb.- n-Dodecylphenol 10 Triton X100 Octylphenol 10 Igepal C0530 6 Igepal 00-630.- 9 Igepal CO730 15 Igepal RC-52 6 Igepal RC-760 "do 11 Igepal DJ-SQO Dinonylphenol l Tall oil alcohol 9 Adol 42-10EO Unhardened tallow alcoho1 10 Alfonic 1418-6. n-Cu-Cm alcohols 1 62. 5 Tergitol 15-8-15 n-On-Cn secondary alcohols 7. 5 Tergitol 15-8-9 .do 9 N eodol 25'9"... Cit-C15 primary straight-chain 2 9 alcohols. Sterox All- Tridecyl alcohol l0 1 Percent.

When the expression straight chain is used herein and in the appended claims. it is intended to include the alcohols which are substantially straight chain, i.e., at least about 70% straight chain with the remainder branched chain.

Other suitable nonionic detergents include the polyoxyethylene polyoxypropylene ethanols having the empirical formula HO(C H O),,(C H O) (C I-I O) H prepared by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol where b is an integer from 26 to 30 and a plus is an integer such as the molecule contains from 0% to 10% ethylene oxide (Pluronic L-60) or from 10% to 20% ethylene oxide (Pluronic L-61) or from 40% to 50% ethylene oxide (Pluronic L-64).

The trisodium nitrilotriacetate serves as an organic sequestrant builder in order to impart heavy-duty (ability to clean soiled clothing) properties to the detergent com: positions. The trisodium nitrilotriacetate is generally present in the compositions in an amount from about 15% to about 35% by weight and more usually it is present in an amount from about 20% to about 30% by Weight, because in this latter range maximum detergency in both cold and hot Water is generally observed.

As noted above, the detergent emulsion compositions contain a ternary stabilizer system in order that the emulsions will be phase-stable upon prolonged storage. The first stabilizer of the ternary stabilizer system is a combination of a hydrolyzed linear copolymer of ethylene and maleic anhydride plus a hydrolyzed cross-linked copolymer of ethylene and maleic anhydride. Generally from about 0.6% to about 1.2% by weight, and more usually from about 0.8% to about 1% by weight of the first stabilizer combination is used. The relative amounts of the linear and cross-linked copolymers may vary depending upon molecular weight, degree of cross-linking and other factors, but usually the cross-linked copolymer is present in a greater amount than is the linear copolymer. These copolymers, as noted hereinafter, are added to the compositions in their anhydride form and then hydrolyzed to their acid form. They exist in the finished product either in the acid or salt form depending upon the alkalinity of the finished product.

Suitable linear copolymers of ethylene and maleic anhydride are available from the Monsanto Company under the designations DX84021, DX840-3l BX-8404 118, etc. Cross-linked copolymers are available under the designations DX-840-61, BX-84041, DX-84081, DX-840 9l and similar materials in this series. In general, the monomers are polymerized at 1:1 ratio, the resin having molecular weights ranging from about 1500 and upwards. The cross-linked copolymers are generally cross-linked with a diamine, an alkylene polyamine, or a diolefinic material such as an ether or a hydrocarbon, etc. Examples of polyamine crosslinking agents include diethylene triamine, triethylene tetramine, tetraethylene pentamine, and higher molecular weight polyethylene polyamines. Exemplary diolefinic cross-linking agents include divinyl benzene, diallyl ether, vinyl crotonate, diallyl esters, and the like. The linear and cross-linked copolymers which can be utilized in preparing the compositions of the invention include the following:

I Determined on a 1% solution of the resin in dimethyl formamide at 25 C.

Cross-linked resin: Viscosity in cps.

DX-840-6l 12,000 DX-840-71 40,000 DX84081 80,000 DX-840-91 160,000

llleasureinents made alt 25 C. on a 1% aqueous solution, adjusted to pH 9 with ammonium hydroxide, using a Brookfield Viscometer, N0. 6 spindle at r.p.m.

The second stabilizer of the ternary stabilizer system is a hydrotrope which serves to help solu'bilize the synthetic organic nonionic detergent in the aqueous medium in spite of the presence therein of the trisodium nitrilotriacetate. The hydrotrope is generally present in the emulsion compositions in an amount of from about 2% to about 8% by weight, and more usually it is present in an amount from about 4 to about 6% by weight. Hydrotropes are Well-knwon materials and include methyl Carbitol (diethylene glycol monomethyl ether), and the alkali metal salts of short chain alkyl aryl sulfonates, such as sodium and potassium xylene sulfonates, sodium and potassium toluene sulfonates, mixtures thereof, and the like.

The third stabilizer component of the ternary emulsion stabilizer system is a strong or weak electrolyte. In view of the fact that electrolytes are known to salt out nonionic organic detergents from aqueous media, it is indeed quite unexpected that an electrolyte would serve as an emulsion stabilizer component for the ternary emulsion stabilizer system used in the compositions of the invention. The electrolyte is generally present in the emulsion compositions of the invention in an amount from about 4% to about 15 by weight and more usually it is present in an amount from about 6% to about 10% by weight. The electrolyte can be an inorganic or an organic compound, typical suitable examples of which include the alkali metal, e.g., sodium and potassium, silicates, sulfates, carbonate, pyrophosphates, chlorides and orthophosphates, and ethylene diamine tetraacetic acid.

Since the ternary stabilizer system contains three components each exerting its respective cooeprative influence as an emulsion stabilizer, and since the chemical nature of each of the component stabilizers can be considerably varied, it will be appreciated that the above amounts of stabilizer components are general ranges which have been found to be operable. However, in view of the variable effectiveness of the stabilizer components, the above amounts thereof are adjusted, as necessary, to maintain the emulsion composition in a phase-stable form. For example, as the amount of electrolyte is increased, the amount of hydrotrope should also generally be increased.

In addition to the above-mentioned components, the phase-stable, heavy-duty liquid detergent emulsion compositions can contain various compatible adjuvants, as desired. For example, soil anti-redeposition agents, such as sodium carboxymethyl cellulose, can be included therein, generally in an amount up to about 1.0% by weight, although such agents tend to decrease phase stability. The compositions can further contain the well-known anionic and nonionic fluorescent dyes or optical brighteners which are usually present in a very small amount, such as about 0.2% by weight. Regulators of pH, such as potassium hydroxide, can also be included. The presence of potassium hydroxide is particularly desirable when the electrolyte is a silicate in order to prevent separation of the silicate from the emulsion. Usually small amounts of pH adjusters are employed, for example, up to about 1% by weight. Other compatible adjuvants which may be included in the emulsion compositions are perfumes, colorants, germicides, and the like, which are generally present in small amounts below about 0.5% by weight.

The phase-stable, heavy-duty liquid detergent emulsion compositions of the invention can be readily processed or prepared, provided certain percautions are taken. Thus, the linear and cross-linked ethylene-maleic anhydride copolymeric stabilizer component in substantially anhydrous form must be rapidly dispersed in an aqueous solution in the presence of the synthetic organic nonionic surfactant and preferably also in the presence of the hydrotropic stabilizer component. It is preferred that the copolymer be dispersed in an aqueous solution which already contains the nonionic detergent. However, the copolymers and nonionic detergent can be simultaneously dispersed in the aqueous solution, the main requirement being that the copolymers are hydrolyzed in the presence of the nonionic detegent. It is preferred that the aqueous solution be at an elevated temperature, for example, ISO-160 F., to accelerate hydration of the anhydride portion of the copolymers to the acid form.

A further precaution is that extraneous alkaline materials should generally not be present during the hydration of the copolymers. Thus, after hydrolysis the pH of the solution should be definitely on the acid side, for ex ample, a pH of about 2.5-3.2. A further precaution in regard to the copolymers is that they should be rapidly dispersed in the aqueous medium.

Another percaution in the preparation of the compositions of the invention is that an alkali, such as potassium hydroxide, should be added to the formulation before the addition of the electrolyte thereto when the electrolyte comprises a silicate. An additional precaution is that the finished formulaions should be homogenized, generally at a temperature ranging from room temperature to about 170 F. and at a pressure of about 500-3000 pounds per square inch.

A suitable order of addition of the components is as follows: water; hydrotrope; nonionic detergent (containing any nonionic fluorescent dyes); linear and cross-linked copolymers of ethylene and maleic anhydride; trisodium nitrilotriacetate; electrolyte (preceded by an alkali, such as potassium hydroxide, when the electrolyte comprises a silicate); any anionic fluorescent dyes; and any soil antiredeposition agents. The formulation is then homogenized.

The compositions are used in the conventional manner for liquid heavy-duty detergent products, e.g., about one-half cup thereof per washing machine load.

The compositions set forth in Tables I and II below were prepared by the above procedure and were then tested for phase stability by a severe accelerated phase stability test. In the accelerated phase stability test a sample of the detergent emulsion composition was placed in a centrifuge tube and the tube inserted into a centrifuge which was then rotated for 30 minutes at 5,000 rpm. which is equivalent to a centrifugal force of about 5,000 g. The term phasestable as used in the specification an claims means that by this severe accelerated phase stability test, the compositions showed a phase separation or multi-layered appearance of only 20% or less. A phase separation of 20% or less by this test is equivalent to a shelf-life of about 6 months or longer.

The detergent compositions set forth in Table I below are presented for comparative purposes and do not constitute formulations falling within the scope of the invention. They do illustrate, however, the necessity for the ternary stabilizer system and the requisite amounts of stabilizer components since they all had a phase separation greater than 20%.

TABLE I In comparative Example A in Table I above, there was neither a hydrotrope nor an electrolyte present and accordingly the composition showed a phase separation by the above test procedure of In comparative Examples B and C, the compositions were free from any hydrotrope component and accordingly these compositions showed a phase separation of 40% each. Comparative Example D was free from an electrolyte and hence had a phase separation of 40%. Comparative Examples E, F and G contained the requisite components of the ternary stabilizer system but contained an inadequate amount of hydrotrope component, namely, an amount thereof below about 2%, and hence these comparative compositions showed a phase separation ranging from a 35% to 45%. In comparative Example H which contained the requisite ternary stabilizer system components, the amount of hydrotrope stabilizer component was in excess of the requisite maximum amount of about 8% and accordingly this comparative composition showed phase separation immediately after preparation and before centrifugation. The remaining comparative Examples I and I also contained the requisite ternary stabilizer systern components but contained an inadequate amount of the electrolyte, namely, an amount below about 4%, so that these compositions showed a phase separation of 29% and 30% respectively.

The compositions set forth in Table II below are representative of the phase-stable, heavy-duty, liquid detergent emulsion compositions of the invention which contained the ternary stabilizer system in the requisite amounts of stabilizer components.

It will be noted that all of the examples in Table II above were phase-stable by the above test procedure in that they showed a phase separation of only 20% or less, ranging to a remarkably low value of only 1.5% phase separation for Example 10. The examples in Table II further illustrate representative variations in the essential and optional components of the compositions of the invention and in the varying amounts thereof which may be employed.

The compositions of the invention are not only phasestable as shown by the data set forth in Table II above, but further tests thereon have established that they possess remarkable detergency properties. In this connection detergency tests have shown that the representative formulation of Example 8 is superior in both hot and cold water detergency to the leading granular detergent composition on the market. Thus, in cold water F.) and hot water (130 F.) having a hardness of 180 p.p.m. the average detergency units for the cleansing of cotton/ Dacron cloth soiled with vacuum cleaner dirt were as follows: Example 8:232, leading granular detergent composition=19.4 (for cold water): and Example 8:

Example N0 Components:

Neodol 25-9 8 Trisodiurri nitrilotrlaeetate S9dium carboxymethyl cellulose. Fluorescent dyes Potassium hydroxide- Water Percent phase separatiorL... Viscosity (cps) 0.' s Amount sufiicient to br 55 40 40 4 I of s .I 0. 0.8

ng total of compositions to by weight 1 Phase separation after preparation;

9 sisting of sodium silicate and sodium sulfate, and the bal- OTHER REFERENCES ance substantially waterthe above amounts of the three i o Acid Chelatin 3 g Agents 1n Detergent Applicasiablhzer onents bemg adlutsed to mamtam the emul' tions, Pollard, Soap and Chemical Specialties, September slon composition phase-stable. 1966 pp 5862 and 130435.

References Cited HERBERT B. GUYNN, Primary Examiner UNITED STATES PATENTS 3,346,504 10/1967 Herrmann 2s2 137 WILLIS Assistant Examiner 3,346,873 7/1967 Herrmann 252-137 3,351,557 11/1967 Almstead et a1 252 106 1 252--138, 152, 161 FOREIGN PATENTS 1,439,308 4/1966 France 252138