WO1992020773A1

WO1992020773A1 - Cleaning composition

Info

Publication number: WO1992020773A1
Application number: PCT/US1992/003426
Authority: WO
Inventors: Patrick C. Hu; Raynold Corona; Edward F. Zaweski; Jennifer C. Lewis
Original assignee: Ethyl Corp
Current assignee: Ethyl Corp
Priority date: 1991-05-10
Filing date: 1992-04-24
Publication date: 1992-11-26
Anticipated expiration: 1993-11-10

Abstract

The cleaning effectiveness of a microemulsion cleaning composition is improved by formulating it so as to contain at least 2 % by weight of a surfactant, be capable of absorbing at least 0.2 % by weight of oil by spontaneous emulsification when contacted therewith, and provide an interfacial tension not higher than 0.1 erg/cm2 when contacted with more oil than can be thus absorbed. Typically the compositions of the invention comprise 2-35 % by weight of the surfactant, 0-35 % by weight of a co-surfactant, 0.5-20 per cent by weight of an electrolyte, 0.5-45 % by weight of an oil, and 15-95 % by weight of water.

Description

CLEANING COMPOSITION

Field of Invention

This invention relates to cleaning compositions having improved effectiveness in removing oily soils from substrates.

Background

There are many known compositions for removing oily soils from laundry, floors, wall tiles, ovens, dishes, and other substrates. At one time the cleaning compositions that were used to effect the soil removal were either surfactant solutions or ordinary emulsions, such as the two-phase laundry prespotting composition of U. S. Patent 4,749,516 (Brusky). However, more recently, micro- emulsion cleaning compositions have also been employed.

Known microemulsion cleaning compositions include those of U. S. Patent 4,919,839 (Durbut et al.), U. K. Patent Application 2,190,681 (Loth et al.-I), and European Patent Applications 0316726 (Loth et aL-H) and 0368146 (Loth et al.-π).

As mentioned in Durbut et al., microemulsions have been discovered to be more effective cleaners than surfactant solutions or ordinary emulsions. However, it would be desirable to find cleaning compositions which would be even more effective than the known microemulsion cleaning compositions.

Summary of Invention

The novel cleaning compositions of the invention are oil-absorbent microemulsion cleaning compositions which have a surfactant content of at least 2% by weight and a mimmum oil absorbency of 0.2% by weight, spontaneously emulsify oil which is contacted therewith until no more oil can be absorbed, and then provide an interfacial tension not higher than 0.1 erg/cm² in contact with any excess oil.

Detailed Description

The cleaning compositions of the invention are microemulsions which remove soil from substrates by the mechanism of spontaneous emulsification - a mechanism which is more efficient than the roll-up mechanism by which most conventional cleaning compositions remove soil. They are more effective cleaners than known microemulsion cleaning compositions because of their providing spontaneous emulsification (i.e., emulsification that occurs without input of energy such as shaking, mixing, or other form of agitation) and a much lower interfacial tension when contacted with excess oil, i.e., an amount of oil exceeding the amount that is spontaneously absorbed thereby.

Since it is their characteristics of spontaneously absorbing oil and then providing that low interfacial tension which are important, their particular compositional makeup is not critical. The compositions may have any components which, in combination with the surfactant, provide that spontaneous emulsification and low interfacial tension. However, most commonly, they comprise 2-35%, preferably 3-25% by weight of a surfactant; 0-35%, preferably 0-10% by weight of a co-surfactant; 0.5-20%, preferably 1-15% by weight of an electrolyte; 0.5-45%, preferably 1-40% by weight of an oil; and 15-95%, preferably 40-90% by weight of water.

The surfactant used to prepare a cleaning composition of the invention should ordinarily be a surfactant having an HLB number of 3-16, preferably 4-15; and it may be composed of one or more surfactants selected from anionic, cationic, nonionic, and amphoteric surfactants.

Exemplary of utilizable surfactants are:

(1) anionic surfactants, such as the sodium, potassium, calcium, barium, magnesium, ammonium, and hydroxyalkylammonium sulfonates, s ulfates, carboxylates, phosphates, sulfosuccinates, and other succinate derivatives containing an organic hydrophobic moiety of 8-26 carbons, preferably 10-18 carbons, such as the fatty acid soaps, N-acylsarcosinates, alkylbenzenesulfonates, α-olefinsulfonates, alcohol sulfates, ethoxylated alcohol s ulfates, and ethoxylated alkylphenol sulfates,

(2) cationic surfactants, such as dodecyldimethylammonium chloride and other quaternary ammonium, phosphonium, and sulfonium halides, acetates, and nitrites, containing a detergent-range hydrophobic moiety,

(3) nonionic surfactants, such as alcohol ethoxylates, alkylphenol ethoxylates, carboxylic acid esters, glycerol esters, polyoxyethylene esters of fatty acids, anhydrosorbitol esters, ethoxylated anhydrosorbitol esters, glycol esters of fatty acids, fatty acid diethanolamides and monoalkanolamides, polyoxyethylene fatly acid amides, ethylene oxide-propylene oxide copolymers, and tert-amine oxides, and

(4) amphoteric surfactants, such as tetradecyldimethylbetaine, hexadecyldimethylbetaine, and other alkyldimethylbetaines in which the alkyl group contains 12-18 carbons.

Such surfactants, of course, are well known and are discussed, e.g., in Kirk-Othmer, Encyclopedia of Chemical Technology. Third Edition, Volume 22, 1983, pp-332-387.

It is sometimes desirable to minimize the amount of electrolyte and/or co-surfactant that might have to be used in conjunction with the surfactant to form an oil-absorbent microemulsion which provides the required lowinterfacial tension in contact with excess oil. When such minimization is desired, the use of a surfactant having a higher molecular weight is apt to reduce the amount of electrolyte required; and the use of a branched surfactant instead of a straight-chain surfactant can sometimes reduce both the electrolyte and the co-surfactant requirements. The surfactants which are apt to be preferred are those comprising or consisting of an anionic surfactant, especially when the anionic surfactant is a sulfate, sulfonate, or phosphate in which the lipophilic portion of the molecule corresponds to one of the formulas:

RR'CH(CH₂)_m(OCH₂CH₂)_n- and

R"CH=CR(CH₂)_m(OCH₂CH₂)_n- wherein R and R' represent alkyl groups containing at least six carbons, generally 6-20 carbons; R" is an alkyl group containing at least five carbons, generally 5-20 carbons; m is 1 or 2; and n is 0 or an integer of 1-20. These preferred surfactants include, e.g., the sodium, potassium, and ammonium sulfates, sulfonates, and phosphates in which the lipophilic moiety is 3-hexylundecyl_. 2-hexyldecyl, or 3,6,9-trioxa-12-hexyleicosyl (also designated as ω-(3- hexylundecy trioxyethylene).

A co-surfactant is sometimes needed to enhance the formation of a microemulsion and modify the rheological properties of the system. When a co- surfactant is employed, it is ordinarily an organic compound having a water solubility of 0.1-50% by weight. The preferred co-surfactants are butanol and 2-hexoxy- ethanol. However, other alcohols, ethoxylated ethers of alcohols and alkylphenols, glycols, glycol ethers, amines, amides, and organic halides are also utilizable, e.g., carbon tetrachloride, methylene chloride, hexylamine, N-methyl-2-pyrrolidone, hexanol, ethylene glycol, diethylene glycol, 3-(3-met ιoxypropoxy)propanol, and an ethoxylated nonylphenol containing three ethoxy groups.

The co-surfactant which is preferred in any instance is apt to be the one that will enhance the formation of a microemulsion and modify the rheological properties of the system at the minimum expense. However, other factors can sometimes make it preferable to use a different co-surfactant For example, another advantage of a different co-surfactant, such as the known usefulness of chlorinated hydrocarbons in cleaning compositions, might make that co-surfactant or a mixture containing it preferable to a co-surfactant which could accomplish the desired modification of properties at a lower cost.

Electrolytes utilizable inpreparing the cleaning compositions include acids, bases, and salts but are usually alkali metal or alkaline earth metal salts (especially the sodium, potassium, barium, calcium, and magnesium salts) or ammonium salts wherein the anion may be inorganic (e.g., halide, hypochlorite, perchlorite, hydroxide, bicarbonate, carbonate, bisulfite, sulfate, sulfonate, nitrate, phosphate, tripolyphosphate, pyrophosphate, or nitrilotriacetate) or organic (e.g., acetate, citrate, polycarboxylate, ethylenecUaminetetraacetate, or carboxymethoxy- succinate).

Although any of these electrolytes can be used when its intended function is simply to enhance the efficacy of the surfactant, it is sometimes desirable to employ a particular electrolyte to serve an additional function. For example, an electrolyte having bleaching capabilities, such as calcium hypochlorite or sodium bisulfite, can have particular value in the cleaning compositions as the sole electrolyte or as a component of an electrolyte mixture. The oils which are used in the cleaning compositions are generally hydrocarbon oils containing 10-60 carbons, although ester and ether oils are also utilizable. Such oils include, e.g., fatty oils, polyalphaolefins, rapeseed oil, sunflower oil, other triglyceride oils, essential oils, mineral oils, isoparaffinic hydrocarbons, low-odor petroleum solvent having a boiling range of 195-250 ° C, kerosene, pine oil, naphtha, perfume oils, such as those containing terpenes, and other oily materials.

Although the particular oil used is not critical from the point of view of permitting the preparation of a microemulsion, the nature of the oil in the microemulsion determines the amount of oily soil that can be absorbed by the composition - larger amounts of oil being absorbable by microemulsions containing an oil which is the same as or very similar to the oily soil to be absorbed.

Thus, when a cleaning composition is being formulated for the treatment of a particular type of oily soil, it is preferred to use the same oil or a similar oil in preparing the microemulsion in order to obtain optimum results. However, adequate cleaning can frequently be achieved with the microemulsions containing different types of oils, especially when the amount of oily soil to be absorbed is low and/or a larger amounts of microemulsion is used.

In the preparation of the micromeulsions of the invention, it is important to appreciate that it is insufficient merely to combine water with the ingredients described above to provide compositions having the aforementioned proportionation of ingredients. Most of the microemulsions thus prepared would be compositions which, like those specifically taught by Durbut et al., would provide interfacial tensions much higher than 0.1 erg/cm², e.g., 1-20 erg/cm², when contacted with excess oil (i.e., more oil than can be spontaneously absorbed) and accordingly would lack the improved cleaning ability of the novel microemulsions.

It is therefore critical to combine the ingredients in the particular proportions which cause the microemulsions to provide interfacial tensions not higher than 0.1 erg/cm², e.g., 0.0001-0.1 erg/cm², when contacted with excess oil. A convenient way of determining the proportions of ingredients to use in preparing a microemulsion of the invention is to (1) choose the particular ingredients which it is desired to employ, (2) add an equal volume of the oil to an aqueous solution of the surfactant and any co-surfactant in order to form a two- phase system, (3) add the electrolyte incrementally until sufficient surfactant has been pushed from the aqueous phase to result in the formation of a surfactant-rich middle-phase microemulsion, (4) analyze the composition of the middle phase, (5) recombine all of the ingredients of the middle phase except for the oil, and (6) incrementally add the oil until the composition contains sufficient oil for a microemulsion to be formed.

The microemulsion prepared by this technique is an oil-absorbent microemulsion that provides the desired low interfacial tension when contacted with excess oil, and it retains those characteristics even when the amount of oil used in its preparation is somewhat more than the amount barely enough to result in the formation of a microemulsion. However, it is generally preferred to use the minimum amount of oil required for microemulsion formation in order to ma_imi_e the amount of oily soil that can be absorbed by spontaneous emulsification when contacted with the microemulsion. like the compositions of Durbut et al., the microemulsions of the invention can be used in neat form (but, unlike the Durbut et al. compositions, only occasionally in dilute form) to remove oily soil from laundry, floors, wall tiles, ovens, dishes, and other surfaces; and they may be applied by means of a sponge or cloth or by soaking. Also, they may be modified by the inclusion of minor amounts of additives, such as the dyes, perfumes, and preservatives frequently used in cleaning compositions.

In a preferred embodiment of the invention, the microemulsions are used as spot remover formulations to be applied to laundry prior to washing - an application in which they have been found to be superior to a commercial composition which is sold for this purpose.

The following examples are given to illustrate the invention and are not intended as a limitation thereof. Unless otherwise specified, quantities mentioned in the examples are quantities by weight.

EXAMPLE I

Several microemulsions were prepared by (1) adding an equal volume of mineral oil to an aqueous solution of a surfactant and co-surfactant in order to form a two-phase system, (2) adding an electrolyte incrementally until sufficient surfactant has been pushed from the aqueous phase to result in the formation of a surfactant-rich middle-phase microemulsion, (3) analyzing the composition of the middle phase, (4) recombining all of the ingredients of the middle phase except for the oil, and (5) incrementally adding the oil until the composition contained sufficient oil for a microemulsion to be formed. The compositions of the microemulsions thus formed are shown below.

NaCl 2.9 Mineral oil 8.5

Water 69.6

Each of these emulsions had an oil absorbency of at least 0.2%, spontaneously emulsified oil in contact therewith until no more oil could be absorbed, and then provided an interfacial tension not higher than 0.1 erg/cm² in contact with excess oil. The oil absorbency was determined by adding incremen¬ tal amounts of mineral oil to the formulations, providing minimal agitation to accelerate the evaluation of the microemulsion efficacy. The maximum oil absorbency was determined at the point that the isotropic imαo-emulsion converted to a turbid system.

EXAMPLE π

Formulation A of Example I was tested for effectiveness as a pre-wash spot remover by:

(1) dipping three swatches of a dust/sebum-soiled polyester/cotton (65/35) fabric having a permanent press finish in the formulation for five seconds and then waiting different lengths of time (10 minutes, five minutes, and one minute, respectively) before placing them in a washing machine, (2) placing the swatches in a washing machine together with (a) three other swatches of the soiled fabric that had been pre-treated in the same way except for the use of a commercial pre-wash spot remover instead of Formulation A and (b) six other swatches of the soiled fabric that had not been pre-treated, (3) washing the swatches in the presence of a commercial laundry detergent and then drying them in a tumble dryer, and

(4) measuring the reflectance of each swatch with a Hunterlab Tristimulus Colorimeter, Model D25M-9.

The results of the test are shown below, the values given for the untreated fabric being the averages of the values obtained for the six control swatches.

Pre-wash Treatment

Formulation Time .min..

None ~ 69.71

Commercial 1 73.03 5 74.34

10 74.46

73.94

A 1 75.50

5 75.84 10 76.07

75.80

The above test results show that the microemulsion of the invention is significantly better than the commercial formulation in removing oily soil by pre- wash application.

Claims

Claims:

1. An oil-absorbent microemulsion cleaning composition which has a surfactant content of at least 2% by weight and a minimum oil absorbency of

0.2% by weight, spontaneously emulsifies oil which is contacted therewith until no more oil can be absorbed, and then provides an interfacial tension not higher than

0.1 erg/cm² in contact with excess oil.

2. The composition of claim 1 comprising 2-35% by weight of the surfactant, 0-35% by weight of a co-surfactant, 0.5-20% by weight of an electrolyte, 0.5-45% by weight of an oil, and 15-95% by weight of water.

3. The composition of claim 2 comprising 3-25% by weight of the surfactant, 0-10% by weight of the co-surfactant, 1-15% by weight of the electrolyte, 1-40% by weight of the oil, and 40-90% by weight of water.

4. The composition of claim 3 wherein (a) the surfactant has an HLB number of 3-16 and is one or more surfactants selected from anionic, cationic, nonionic, and amphoteric surfactants, (b) the co-surfactant is an organic compound having a water solubility of 0.1-50% by weight, (c) the electrolyte is an ammonium, alkali metal, or alkaline earth metal salt, and (d) the oil is a hydrocarbon oil containing 10-60 carbons or a triglyceride oil.

5. The composition of claim 4 wherein the surfactant comprises an anionic surfactant having an HLB number of 4-15 and the co-surfactant is at least one co-surfactant selected from alcohols, ethoxylated ethers of alcohols and alkylphenols, glycols, glycol ethers, amines, amides, and organic halides.

6. The composition of claim 5 wherein the anionic surfactant is a sulfate or sulfonate in which the lipophilic portion of the molecule corresponds to one of the formulas:

RR'CH(CH₂)_m(OCH₂CH₂)_n- and R"CH=CR(CH₂)_M(OCH₂CH₂)_n- wherein R and R' represent alkyl groups containing at least six carbons, R" is an alkyl group containing at least five carbons, m is 1 or 2, and n is 0 or an integer of 1-20.

7. The composition of claim 5 wherein the co-surfactant is butanol,

2-hexoxyethanol, or N-methyl-2-pyrπ.lidone.

8. An oil-absorbent microemulsion cleaning composition which is suitable for use as a pre-laundry spot remover and which comprises 2-35% by weight of a surfactant, 0-35% by weight of a co-surfactant, 0.5-20% by weight of an electrolyte, 0.5-45% by weight of an oil, and 15-95% by weight of water in such proportions so as to absorb at least 0.2% by weight of oil spontaneously and provide an interfacial tension not higher than 0.1 erg/cm² when contacted with oil in excess of the amount that can be absorbed spontaneously.

9. The composition of claim 8 comprising 3-25% by weight of a surfactant which has an HLB number of 3-16, 0-10% by weight of an organic co- surfactant having a water-solubility of 0.1-50% by weight, 1-15% by weight of an ammonium, alkali metal, or alkaline earth metal salt as the electrolyte, 0.5-45% by weight of a hydrocarbon oil containing 10-60 carbons, and 40-90% by weight of water.

10. The composition of claim 9 wherein (a) the surfactant comprises an anionic surfactant which has an HLB number of 4-15 and is a sulf ate or sulfonate in which the lipophilic portion of the molecule corresponds to one of the formulas:

RR'CH(CH₂)_m(OCH₂CH₂)_n- and R"CH=CR(CH₂)_m(OCH₂CH₂)_n- wherein R and R' represent alkyl groups contaimng at least six carbons, R" is an alkyl group containing at least five carbons, m is 1 or 2, and n is 0 or an integer of 1-20 and (b) the co-surfactant is at least one co-surfactant selected from alcohols, ethoxylated ethers of alcohols and alkylphenols, glycols, glycol ethers, amines, amides, and organic halides.