EP0131394B1

EP0131394B1 - Hard surface acid cleaner

Info

Publication number: EP0131394B1
Application number: EP84303999A
Authority: EP
Inventors: Kin-Man Choy Clement
Original assignee: Clorox Co
Current assignee: Clorox Co
Priority date: 1983-07-07
Filing date: 1984-06-13
Publication date: 1988-02-17
Also published as: DE3469363D1; EP0131394A2; MX159252A; ES534403A0; CA1217690A; JPH0699704B2; ES8704887A1; ATE32521T1; ES557353A0; EP0131394A3; ES8802535A1; JPS6015499A

Abstract

Hard surface acid cleaners providing fast acting and effective cleaning results across a wide variety of problematic cleaning areas, comprise alkyl aryl sulfonic acids and at least 50.0% by weight of water. Suitable alkyl aryl sulfonic acids are alkyl benzene sulfonic acids of the general structure <CHEM> wherein R is alkyl averaging 5 to 20 carbon atoms in length and <CHEM> wherein R1 and R2 are H or alkyl averaging 5 to 20 carbon atoms; and when R1 is alkyl, R2 is H. Additionally, solvents, antimicrobial compounds, defoamers, thickeners and other cleaning adjuvants may be added to these hard surface acid cleaners.

Description

There are many examples of hard surface cleaners in the art, containing some sort of anionic surfactant, solvent, perhaps a dye and a fragrance to impart a pleasing color and odor, and mostly water. Most of these prior cart cleaners suffer from one or more disadvantages. For example, some cleaners are effective only on hard water stains. An example of this class of cleaner is a highly acidic toilet bowl cleaner containing hydrochloric acid. Hard water stains are mineral stains caused by the deposition of calcium or magnesium salts present in hard water. Certain other cleaners may be effective only against soap scum stains, caused when a fatty acid soap, such as a sodium lauryl fatty acid soap precipitates in hard water containing alkaline earth metal salts, such as calcium, magnesium, or barium, causing the familiar soap scum stain. Still other cleaners may be effective only on greasy/oily stains. Generally speaking, these are cleaners which have either at least some water miscible solvent, and/or some higher amount of nonionic and/or anionic surfactants.
None of the prior art cleaners have addressed all three of these problematic areas together. As mentioned, a particular cleaner may be effective against a particular stain or cleaning problem, but not against the others. Thus, ineffective cleaning results may occur against certain stains using some of the cleaners, requiring purchase of other cleaners which will effectively remove the target stain. This will result in added expense as a particular cleaner must be purchased for a particular stain.
Furthermore, may of the prior art cleaners are very slow-acting. That is, after being applied to a target stain for long periods of time, they may show some cleaning effect, but this slow action is considered a great disadvantage and inconvenience.
Thus, heretofore no single cleaner has been formulated which will satisfactorily clean all types of stains. There is also a need for an effective all purpose'hard surface cleaner which is faster than the prior art cleaners. There is thus a long felt need for a multipurpose household cleaner capable of quickly and effectively cleaning all three types of stain.
Linear alkyl benzene sulfonic acid has been well known in the detergent and cleaner field as storage compound which, upon neutralization with generally, an alkali metal salt, is available for use as an anionic surfactant. This was recognized in Kappler, et al, U.S.-A-3,969,282 which utilized alkyl benzene sulfonic acid in combination with a nonionic surfactant as a storage compound to be neutralized with alkali metal salts prior to using them to launder fabrics. Further, Reid, U.S.-A-2,463,936 showed that linear alkyl benzene sulfonic acids could be neutralized with triethanolamine to act as a cleaner. However, it was not realized in the art that linear alkyl benzene sulfonic acids can be utilized as hard surface cleaners themselves.
This invention relates to an improved, hard surface acid cleaner comprising

(a) alkyl aryl sulfonic acid of formula (I)
wherein R is an alkyl averaging 5 to 20 carbon atoms; or formula (11)
wherein R, and R₂ are H or alkyl averaging 5 to 20 carbon atoms, when R, is alkyl R₂ is H;
(b) a solvent selected from C_1-10 alkanols, C_5-10 alicylic alkanols, C₂-, dialkyl ethers and C_3-20 glycol ethers and mixtures thereof; and
(c) at least 25.0% by weight water.

In another embodiment, the hard surface acid cleaner further comprises an antimicrobial compound selected from:

(i) a substituted phenol of the general structure:
wherein R,, R₂, R₃, R₄, and R₅ can be a phenyl group, substituted phenyl, CI or H, and R₆ can be H or Na;
(ii) a quarternary ammonium compound; and
(iii) mixtures thereof.

In yet another embodiment, the hard surface cleaner further comprises a thickener selected from gums, polysaccharides and resins.
In still another embodiment, the hard surface acid cleaner further comprises a defoamer selected from the dialkyl polysiloxane polymers.
The hard surface acid cleaner of this invention can also include at least one other cleaning adjuvant selected from dyes, pigments, fragrances, and builders.
Surprisingly, the hard surface acid cleaner of this invention has proven to be both effective and fast- acting against all three major problem stains, namely, (1) soap scums; (2) hard water stains; and (3) greasy/ oily stains.
The present invention is a hard surface acid cleaner which has surprisingly effective and fast cleaning results on all three problem areas: (1) soap scums; (2) hard water stains; and (3) greasy/oily stains. The surprising revelation was that alkyl aryl sulfonic acid compounds, most particularly, linear alkyl benzene sulfonic acids, ("HLAS") were responsible for the improved cleaning in all three areas. These alkyl benzene sulfonic acid surfactants are not neutralized with alkali metal, alkaline earth metal, or ammonium salts as are the typical detergents using substituted alkyl benzene sulfonates.
The linear alkyl benzene sulfonic acids used in this invention are, as previously mentioned, commonly neutralized with sodium or other alkali metal salts to make common cleaners. Linear alkyl benzene sulfonic acid itself is produced by a two step synthesis, in which benzene is first alkylated with some alkyl chloride in the presence of catalyst. Next, the alkylated benzene is reacted with sulfonating reactant. A third step, which does not concern the present invention, can occur when the thus produced linear alkyl benzene sulfonic acid is neutralized with an alkali metal hyroxide, such as NaOH, to produce the sodium salt, which is commonly called "LAS".
Linear alkyl benzene sulfonic acid - which was introduced for heavy industrial use, after it was discovered that branched alkyl benzene sulfonic ("ABS") was significantly less bio-degradable - is produced by many companies, including Continental Oil Company under the brand name of Conoco SA-597, and Pilot Chemical Company under the brand name Calsoft LAS-99, Witco Chemical Corporation under the brand name of Witco 1298 Soft Acid and Stepan Chemical Company under the brand name of Bio Soft S-100.
Linear alkyl benzene sulfonic acid has the general structure (I) above.,
Most preferable for use in the formula of this invention are dodecylbenzene sulfonic acids, wherein R averages about 11.4 carbon atoms in length.
Other alkyl aryl sulfonic acids suitable for use in this invention include alkylated diphenyl oxide disulfonates of the general structure (II) above.
Preferably, a range of 0.001 % to 50.0% particularly, 1.0% to 30.0% and most preferably 5.0% to 15% by weight of acid surfactant is present in compositions of this invention. Further, the preferred surfactant of this invention will cause the formulas of this invention to have.pH's of no more than 6.5, and preferably, below 3.
An example of a suitable alkyl sulfonic acid in Dowfax 2AO manufactured by Dow Chemical Company corresponding to the structure immediately above when R, is H and R₂ averages 12 carbons.
Solvents appropriate for use in this invention include C_l-_lo alkanols such as straight chain, primary, secondary and tertiary C_1-10 alkanols, C_S-_1o alicyclic alcohols, C₂-₈ dialkyl ethers, C₃-₂₀ glycol ethers such as C₃-₂₀ acyl and aryl glycol ethers and mixtures thereof.

1. Alkanols: appropriate alkanol solvents in this invention include those having the general formula R-OH where R can be a straight, or substituted carbon chain of 1-10 carbon atoms. Solvents of this type include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec butanol, tert butanol, hexanol, heptanol, etc.
2. Aliphatic Cyclic Alcohols (Alicyclics): Further appropriate solvents herein are ring structures, such as cyclohexanol, cyclooctanol and cyclodecanol and average 5-10 carbon atoms in their ring structures.
3. Dialkyl ethers: the dialkyl ethers suitable for use as solvents in this invention have a general structure R-O-R,, wherein R and R₁ are equal, and each comprise a carbon chain of at least 1. The dialkyl ethers herein comprise two to eight carbon atoms in average chain length. Examples of this particular group of solvents include dimethyl ether, diethyl ether, and dipropyl ether.
4. Glycol ethers: particularly preferred as solvents in this invention are the glycol ethers having the general structure R-0-R,-OH, wherein R is an alkoxy of 1 to 20 carbons atoms, or aryloxy of at least 6 carbon atoms, and R₁ is an ether condensate of propylene glycol and/or ethylene glycol having from one to ten glycol monomer units. Preferred are glycol ethers having one to five glycol monomer units. These are C₃-₂₀ glycol ethers.

Examples of particularly preferred solvents include propylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol isobutyl ether, ethylene glycol methyl ether, ethylane glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, ethylene glycol phenyl ether, and propylene glycol phenol ether.
These glycol ethers are especially preferred because they are colorless liquids with mild, pleasant odors. They are very miscible with water, and have been found to be especially stable with the acid surfactants noted above.
Addition of 0.001-25.0% by weight of any of the solvents disclosed to this hard surface acid cleaner appears desirable, and especially preferred is 0.1 to 15% by weight of added solvent. As will be further discussed in greater detail, addition of solvents to the hard surface acid cleaners herein provide surprisingly even greater cleaning benefits.
In yet another embodiment of this invention, antimicrobial compounds are added to the novel hard surface cleaners of this invention which are selected from substituted phenols and quaternary ammonium compounds.

1. Substituted phenols: suitable antimicrobial compounds can be selected from the substituted phenols having the general structure
wherein R_i, R₂, R₃, R₄, and R₅ can be phenyl group, substituted phenyl, Cl, H, and the alkali metal salts thereof, and R₆ can be H or Na. Phenols suitable for use in this invention include those sold by Dow Chemical Company under the brand name Dowicide, such as sodium o-phenyl phenol tetrahydrate (Dowicide A), o-phenyl phenol (Dowicide I), 2,4,5 trichloro-phenol (Dowicide II), 2,4,5 trichloro-phenol, sodium salt, 1/2 hydrate (Dowicide B), and pnetachlorophenol (Dowicide EC-7). Further phenols include ortho-benzyl-para-chlorophenol sold under the brand name Santophen I by Monsanto Chemical Corporation.
2. Quaternary Ammonium Compounds: particular, surprisingly effective antimicrobial compounds suitable for use in this invention are quaternary ammonium compounds.

One would normally expect that quaternary ammonium compounds, some of which are cationic surfactants, having essentially positively charged species in aqueous solution, would react with the anionic surfactants in equilibrium with the acid surfactants disclosed above and cause a precipitate to form. However, the quaternary ammonium compounds such as antimicrobial compounds in this invention are miscible with the mixture of acid surfactant and solvent in the formula and do not precipitate. Instead, a thickening is seen to occur when a preferred percentage of up to 5.0% of quaternary ammonium compound. Surpassing 5.0% has a thixotropic effect on the cleaner, and his latter application may be suitable for use as very substantive cleaners, i.e., bathroom cleaners.
Suitable quaternary ammonium compounds include the ammonium salts of the general structure
wherein R and R, are alkyls of 5 to 20 carbon atoms, aryl of 6 to 20 carbon atoms or alkylaryl of 7 to 20 carbon atoms provided that only one of R and R, is aryl or alkylaryl; R, may also be hydrogen and A- is an acid stable anion. Preferred anions include CI-, Br-, I-, SO₄ ^-, CI0₄-, CI0₃-, and N0₃-. Other anions stable in the acid surfactants of this invention are possible. R, can also be an alkyl benzyl group (in which case R is preferably a methyl group).
Preferably R and R, are both alkyl groups.
Further particularly preferred are C₇ to C₁₂ dialkyl dimethyl ammonium salts. Other cationic surfactants, notably other quaternary ammonium salts and tertiary amine surfactants may be suitable for use as disinfectant compounds.
As previously discussed, it is generally unknown why the cationic surfactants used as antimicrobial compounds in this invention are compatible with the acid surfactants. One would normally suspect that the quaternary ammonium compounds would co-precipitate with the anionic form of the acid surfactants. However, a proposed theory, which is not meant herein to be binding, is that these acid surfactants, not being neutralized by any alkali metal salts as the more common anionic surfactants are, may exhibit nonionic moieties in solution which act to solublize the cationic surfactants (quaternary ammonium compounds) and keep them from precipitating with the anion form of the acidic surfactants herein.
Additionally, the antimicrobial compounds can apparently be used in combination. No loss in stability is seen by combining these two antimicrobial compounds. Further, either or both of these antimicrobial compounds may be present in the invention from 0.001 to 15.0% by weight. Particularly preferred percentages of these antimicrobial compounds are from 0.1 to 10% by weight.
Further, approximately 0.0001-25% by weight of further cleaning adjuvants may be added to the present invention. These cleaning adjuvants include thickeners selected from gums, resins and other polysaccharides, such as xanthan gums, starch, and mixtures.
Further cleaning adjuvants include defoamers, such as dialkyl polysiloxane polymers. Particularly preferred as the defoamers are those sold by Dow-Corning under the trade name DB 100 for 100% dimethylpolysiloxane. Further defoamers may be applicable for use in this invention, including various cationic and nonionic surfactants.
Still further cleaning adjuvants include dyes, pigments, fragrances and builders. The dyes and pigments in this invention are merely limited to those which will not substantially deposit and stain the surface to be cleaned. Fragrances selected must generally be those which will not be degraded by the low pH of the hard surface acid cleaner. Builders can include many inorganic and organic builders, such as sodium ethylenediaminetetraacetate or HEDTA (hydroxyethyl ethylenediaminetriacetic acid). Further builders include many organic acids and their alkali metal salts, eg., citric acid, sodium citrate, sodium lactate, sodium maleate, etc.
Various formulations of the hard surface acid cleaners of this invention were assayed in the three soiling problem areas (1) soap scums; (2) hard water stains; and (3) oily/greasy stains, as described in the following section, under "EXPERIMENTAL". Test methodologies and results of assays are set forth in greater detail below.

Experimental

A. Synthetic Soap Scum Test Preparation and Method:

A standard soap scum suspension was prepared using the following ingredients:
This suspension was applied and baked onto tiles which were then cleaned with various formulations of the hard surface acid cleaner (1) using a Gardner Wear Tester (i.e., "Scrubbing Test") and (2) by simple application according to the "Soak Test". Impartial panelists were asked to grade the cleaning of the synthetic soap scum stains by the formulations of this invention as well as the performance of competitive cleaners on a 0 to 5 scale, wherein 0 = no cleaning, 5 = total cleaning. The grading was averaged for a number of trials. These results are reported below in TABLES I, II and III. Competitive products were also tested. Grading was conducted over various time periods to show that the hard surface acid cleaners of this invention clean effectively much more rapidly than competitive products.

B. Hard Water Stain Test Methods:

Two "premixes" were prepared from the following ingredients:
Each premix was sprayed on preheated brown tiles, then baked and allowed to cool.
The tiles were cleaned by applying approximately 4 grams of various formulations of the hard surface acid cleaner, scrubbed and rinsed ("Scrubbing Test"). Impartial panelists then graded the cleaning results on a 0 to 5 scale, as previously discussed. Competitive products were also compared. Further, in a second test, "Soak Test", formulations were allowed to soak the target stain for time intervals of 30, 20, 10, 5, 3, and 1 minutes, or 10, 5, 3, 2, minutes and 45 seconds to demonstrate rapid cleaning efficency. The results are reported in TABLES I, II and III below. Participants noted also how quickly effective cleaning occurred at the various time intervals.

C. Oily/Greasy Soil Test Methods

The following oily/greasy soil mixture was prepared:
This mixture was applied in a thin layer to pre-cleaned white enamalled metal sheets (which material is the same as used for manufacturing porcelain kitchen sinks) and allowed to dry (age) for approximatley 24 hours.
Thereafter, each panel was cleaned via the Oil/Grease Stain "Soak Method", wherein approximately 5 grams of various formulations of the hard surface acid cleaner were applied and allowed to soak for time intervals of 30, 20, 10, 5, 3 and 1 minutes. Competitive products were similarly compared. Speed in cleaning, as previously noted, was scrutinized carefully. The results are reported below in TABLES I, II and III below.
In TABLES IV-V, below, the effect of adding a solvent selected from the preferred solvents discussed previously, to the hard surface acid cleaners of this invention was tested. Surprisingly, it was found that even stronger cleaning performances were obtained without any loss in formula stability.
TABLE VI; below, illustrates the effect of adding a germicidal compound to the hard surface acid cleaners of this invention. As previously discussed, the preferred germicidal or antimicrobial compounds are chosen from substituted phenols, quaternary ammonium compounds, or mixtures thereof. Surprisingly, not only were the phenols stably miscible with the hard surface acid cleaners, but the quaternary ammonium compounds as well. Since the quaternary ammonium compounds are cationic species, i.e., positively charged species in aqueous solutions, it was presumed that precipitation would occur upon combination with the acid surfactants of the present invention. Surprisingly, no precipitation occurred, and the quaternary ammonium compounds also caused a thickening of the formulas when used in percentages of 5.0% or more. Adding more than 5.0% may cause a thixotrope to form, which helps the cleaning formula stay in place when applied to a vertical surface. This is a substantial benefit over other cleaners which are not as substantive and which tend to drain off. Furthermore, as disclosed in TABLE VI below, the antimicrobial activity of the antimicrobial compounds was very efficacious.
Review of TABLES I-VI shows that the hard surface acid cleaners of the present invention show surprising efficacy and fast action.
In direct comparison tests with other commercially available cleaners in TABLES I, II and III, the hard surface acid cleaners showed that total cleaning was consistently achieved, whether a "Scrubbing Test" or "Soak Test" was considered, and cleaning results were achieved faster than when using any of the competitive products. TABLES IV-V disclosed the even greater cleaning efficiency when using a variety of different solvents of varying structures. Further, using more than one type of solvent as in Example 48 is possible, but in the interest of cost effectiveness may not be as desirable, although such increases still constitute a part of this invention. Lastly, TABLE VI shows that effective antimicrobial action is obtained by adding either a substituted phenol, a quaternary ammonium compound, or both, with surprisingly no loss in stability from addition of the quaternary ammonium compound.
The present invention therefore provides a multipurpose, fast acting and effective hard surface acid cleaner which is effective over the three major problem cleaning areas.
The trademarks mentioned herein may be registered in some of the Designated States.

Claims

1. A hard surface acid cleaner characterized by comprising

(a) alkyl aryl sulfonic acid of formula (I)

wherein R is an alkyl averaging 5 to 20 carbon atoms; or formula (II)

wherein R, and R₂ are H or alkyl averaging 5 to 20 carbon atoms and, when R, is alkyl R₂ is H;

(b) a solvent selected from C_1-10 alkanols, C₅₁₀ alicyclic alkanols, C_2-8 dialkyl ethers and C_3-20 glycol ethers and mixtures thereof; and

(c) at least 25.0% by weight water.

2. A hard surface acid cleaner as claimed in claim 1 wherein said alkyl aryl sulfonic acid is present in an amount of 0.001 to 50.0% by weight of the cleaner.

3. A hard surface acid cleaner as claimed claim 1 or claim 2 wherein the solvent is present in an amount from 0.001 to 25.0% by weight.

4. A hard surface acid cleaner as claimed any preceding claim and comprising an antimicrobial compound selected from:

(i) a substituted phenol of general structures:

wherein R,, R₂, R₃, R₄, R₅ can be phenyl, substituted phneyl, Cl, H; and R₆ is H or Na;

(ii) a quaternary ammonium compound; and

(iii) mixtures thereof.

5. A hard surface acid cleaner as claimed in claim 4, wherein the quaternary ammonium compounds has the qeneral structrue:

wherein

R and R, are the same or different

R is alkyl of 5 to 20 carbon atoms, aryl of 6 to 20 carbon atoms or alkylaryl of 7 to 20 carbon atoms and

R, is hydrogen or a group R and

A is an acid stable anion provided that only one of R and R₁ is aryl or alkylaryl

6. A hard surface acid cleaner as claimed in claim 4 or claim 5 wherein the antimicrobial compound is present in an amount from 0.001 to 15.0% by weight.

7. A hard surface acid cleaner as claimed any preceding claim further comprising a thickener selected from gums, resins, polysaccharides, and mixtures thereof.

8. A hard surface acid cleaner as claimed any preceding claim further comprising a defoamer selected from dialkyl polysiloxane polymers.

9. A method of making a hard surface acid cleaner, as claimed in any preceding claim comprising combining the alkyl aryl sulfonic acid, water and solvent as defined in claim 3.

10. A method for cleaning a hard surface having soiling materials thereon comprising contacting the hard surface with acid cleaner as claimed in any one of claims 1 to 8; and removing the soiling materials and the hard surface acid cleaner from the hard surface.