Thickened pourable aqueous abrasive cleanser

Abstract: This invention provides a thickened aqueous hard surface abrasive scouring cleanser having improved cleaning efficacy due to the presence of an organic solvent in the composition. It has surprisingly been found that an organic solvent can be included in an abrasive, surfactant, electrolyte/buffer, soap and colloidal alumina thickened composition without causing the system to become unstable. The abrasive cleanser of this invention has a smoothly flowable or plastic, preferably pourable, consistency and has stable abrasive-suspension characteristics over long periods of time.

Description: The present invention relates to thickened aqueous hard surface abrasive scouring cleansers and more particularly to such cleansers which are characterized by being pourable at room temperature, exhibiting little or no syneresis over time and also having improved cleaning efficacy. BACKGROUND OF THE INVENTION A variety of thickened aqueous scouring cleansers are known in the art and these cleansers exhibit various characteristics. For example, in US-A-4,599,186, US-A-4,657,692 and US-A-4,695,394 to Choy et al. and in US-A-4,842,757 to Reboa et al., thickened aqueous abrasive cleansers are disclosed which use colloidal alumina thickeners to provide abrasive cleansers which exhibit little or no syneresis over time. Other abrasive cleansers are disclosed in US-A-4,676,920 to Culshaw and EP-A-126545 to Buzzaccarini and EP-A-216416 to Iding, which contain clay type thickeners. While these cleansers contain hydrocarbon solvents, the clay thickeners do not provide the desired properties in terms of pourability and resistance to syneresis. The disclosure of Iding indicates that including solvents in abrasive cleanser compositions contributes to the instability and syneresis of these cleansers. Other abrasive cleansers are disclosed in US-A-4,158,553 and US-A-4,240,919 to Chapman; US-A-4,396,525 and US-A-4,129,423 to Rubin; US-A-4,005,027 to Hartman; US-A-4,457,856 to Mitchell; and JP-A-60-108499 to Watanabe et al. None of the cleansers disclosed in these references provide the desired cleaning efficacy for certain applications together with the superior resistance to syneresis and the desired flowable or plastic consistency as exhibited by the Choy et al. cleansers. A specialized emulsion type skin cleaner composition for removing paint is disclosed in US-A-4,508,634 to Elepaño et al. as containing surfactants, solvents, an optional mild abrasive and a thickener as a protective colloid thickener for stabilizing the emulsion, which colloid can be colloidal alumina. In view of the above it has been found that there remains the need for a thickened aqueous abrasive cleanser having the characteristics of: (a) having a smoothly flowable or plastic consistency, preferably pourable, and maintaining these properties over long periods of time; (b) being stably abrasive-suspending, i.e., capable of suspending the abrasive so that it can be used without the need for prior shaking or agitation to resuspend the abrasive after standing for a period of time; and (c) having improved cleaning efficacy for certain applications. In the context of this invention the term "plastic" means that the cleanser is of a consistency which can undergo continuous deformation without rupture or relaxation of that consistency; the term "pourable" means that the cleanser is of a consistency which can be poured from an open container without the need for application of any force other than gravity; and the term "stably abrasive-suspending" means that the abrasive in the cleanser is and remains over long periods of time totally and fully suspended in the cleanser system, thus eliminating any need to shake, agitate or stir the cleanser before use to resuspend the abrasive mixture. In this regard, it should be noted that some liquid separation, i.e., syneresis, can occur in the cleanser, but so long as the abrasives remain fully and totally suspended, the cleanser is considered to be abrasive-suspending stable. Moreover, such liquid separation is not detrimental to dispensing or using the cleanser so long as the abrasive remains fully and totally suspended. SUMMARY OF THE INVENTION It has now been determined that it is desirable to include in a thickened aqueous abrasive cleanser an organic solvent to increase the cleaning efficacy of the cleanser for certain applications. Contrary to the expectations that the addition of an organic solvent to these cleansers would increase syneresis, it has surprisingly been found that a thickened aqueous abrasive cleanser having such desired increased cleansing efficacy can be made including a hydrocarbon solvent and, when used in combination with a fatty acid soap and a colloidal alumina thickener together with conventional electrolyte/buffers and surfactants, a cleanser is provided which also has the above mentioned desirable properties of being smoothly flowable or plastic, preferably pourable, consistency and being stably abrasive-suspending. This improved cleanser may also contain bleach when desired. This improved cleanser is described below in detail. It is an object of the invention to provide a thickened aqueous abrasive cleanser characterized by a rheology and a consistency which remains smoothly flowable or plastic over long periods of time. It is another object of this invention to provide a thickened aqueous abrasive cleanser characterized by being stably abrasive-suspending over long periods of time. It is another object of this invention to provide a thickened aqueous abrasive cleanser characterized by having improved cleaning efficacy. This invention provides a thickened aqueous hard surface abrasive scouring cleanser characterized by being smoothly flowable or plastic and being stably abrasive-suspending comprising: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of the cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming from 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. The hard surface abrasive scouring cleanser of the present invention as summarized above provides excellent suspension of abrasive particles. In addition, the cleanser of the present invention has also been found to surprisingly demonstrate a substantial absence of phase separation of the abrasive. The stably abrasive-suspending cleanser provided by the present invention has also been found to be stable over time and even at relatively elevated temperatures. Because of the resulting physical stability, cleansers provided by the present invention do not require shaking before use in order to re-suspend or re-mix the formulation of abrasives. Rather, the cleansers of the present invention maintain a uniform rheology and have a smoothly flowable or plastic consistency and preferably a pourable consistency even after extended periods of shelf life. Accordingly, the cleansers of the present invention have substantial esthetic appeal while being useful in the sense of being easy to dispense, maintaining solid abrasives and other components in uniform suspension and giving good coverage by preferably flowing down while clinging to vertical surfaces. In another aspect, this invention provides a method for preparing a thickened aqueous hard surface abrasive scouring cleanser having a smoothly flowable or plastic consistency, preferably a pourable consistency, and being stably abrasive-suspending comprising the step of combining: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of the cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming from 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. In another aspect, this invention provides a method for cleaning a surface with a thickened, aqueous cleanser characterized by a smoothly flowable or plastic consistency, preferably pourable, and being stably abrasive-suspending comprising contacting the surface having a stain thereon with the thickened, aqueous cleanser comprising: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming from 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. The present invention has surprisingly demonstrated the ability of the surfactant, alumina colloid, soap and solvent to provide an abrasive cleanser which is not only smoothly flowable or plastic, preferably pourable, and is stably abrasive-suspending but also provides superior cleaning properties. DESCRIPTION OF EMBODIMENTS OF THE INVENTION In one aspect, the present invention provides a thickened aqueous abrasive cleanser characterized by being pourable and having a smooth flowable consistency, these characteristics being retained by the cleanser even over long periods of time. More preferably, the invention provides a hard surface abrasive scouring cleanser having properties of the type described above while also being stably abrasive-suspending, thereby stably suspending the abrasive solids over time. Accordingly, in at least one embodiment of the invention, a thickened, aqueous cleanser having desirable characteristics of a pourable and smooth flowing consistency and being stably abrasive-suspending, comprises: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 10 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present from 0.1 to 10% by weight of the cleanser; (c) an electrolyte/buffer forming from 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. Essential ingredients in the abrasive composition of the invention as summarized above particularly include the colloidal alumina thickener, the surfactant, the soap and the solvent, particularly where the colloidal alumina thickener tends to demonstrate the smoothly flowable or plastic (preferably pourable) and not thixotropic characteristics upon combination with the surfactant, abrasive, soap and organic solvent. In order to provide a more complete understanding of the invention, a summary as to each of the individual components in the composition of the present invention is set forth in greater detail below. Abrasives Abrasives are used in the invention to promote cleaning action by providing a scouring action when the cleansers of the invention are used on hard surfaces. Preferred abrasives include silica sand, but other hard abrasives such as a perlite, which is an expanded silica, and various other insoluble particulate abrasives can be used, such as quartz, pumice, calcium carbonate, feldspar, talc, tripoli and calcium phosphate. Abrasives can be present in amounts ranging from 5% to 70% by weight based on the total weight of the cleanser, preferably from 10% to 60%, and more preferably between 20% and 40%. Useful abrasives are generally sold as grades based on U.S. Mesh Sieve sizes. The U.S. Sieve sizes are inversely related to measurements in microns, wherein 80 mesh sieves correspond to about 180 microns, and 325 mesh sieves correspond to about 45 microns. The particles should have an average size of at least about 10 microns, preferably from about 20 to about 200 microns, more preferably from about 30 to about 100 microns, and usually a preferred useful abrasive will have an average particle size of around 45 microns. Particle hardness of the abrasives can range from Mohs hardness of about 1-10, more preferably 3-8. Abrasives are generally insoluble inorganic materials, although there are some organic abrasives, to wit, melamine granules, urea formaldehyde, corn cobs, rice hulls, etc., which are useful in the cleansers of the present invention. Some thickeners are also insoluble inorganic materials, for instance, the colloidal aluminum oxide thickeners used in this invention. However, the colloidal alumina thickeners used in this invention distinguish from the above aluminum oxide abrasives in many aspects. Colloidal alumina thickeners are dispersable in an aqueous system and have a dispersed average particle size of smaller than one micron and usually much smaller. Aluminum oxide abrasives on the other hand will be much larger, such as up to 500 microns, and even in aqueous dispersion, will not thicken the cleansers of this invention. As mentioned below, the colloidal alumina thickeners must be initially dispersed in acidic media to provide thickening. Further, without the colloidal thickeners of this invention, abrasives, even aluminum oxide abrasives, cannot be stably suspended. Surfactants As mentioned herein above, the surfactants suitable for use in this invention are selected from anionic, nonionic, amphoteric, zwitterionic surfactants and mixtures thereof, which are non-soap type of surfactants. It is especially preferred to use a combination of anionics and bleach-stable nonionics, which are usually more saturated to provide stability in the presence of the bleach. However, when the cleansers of this invention are used as non-bleach formulations, more unsaturation may be present in the surfactants selected. The anionic surfactants useful in this invention can be selected from surfactants such as alkali metal alkyl sulfates, secondary alkane sulfonates, linear alkyl benzene sulfonates, and mixtures thereof. These anionic surfactants will preferably have alkyl chain groups averaging about 8 to about 20 carbon atoms. In practice, it is frequently desirable to have a bleach present in the cleanser. When the bleach is present, the surfactant can be any other anionic surfactant which does not degrade chemically when in contact with a hypohalite, e.g., hypochlorite, bleaching species. An example of a particularly preferred secondary alkane sulfonate is HOSTAPUR SAS, manufactured by Farbwerke Hoeschst A.G., Frankfurt, West Germany. Another example of an alkane sulfonate is Mersolat, which has an alkyl group of about 13-15 carbon atoms and is sold by Mobay Chemical Company. An example of typical alkali metal alkyl sulfates is Conco Sulfate WR, which has an alkyl group of about 16 carbon atoms, and is sold by Continental Chemical Company. When the electrolyte used is an alkali metal silicate, it is most preferable to include with the surfactant a soluble alkali metal soap of a fatty acid, such as a C₆₋₁₈, more preferably C₁₀₋₁₆, fatty acid soap. Especially preferred are sodium and potassium soaps of lauric and myristic acid. Examples of preferred bleach-stable nonionic surfactants are amine oxides, especially trialkyl amine oxides. A representative structure is set forth below: In the structure above, R′ and R″ can be alkyl of 1 to 3 carbon atoms, and are most preferably methyl, and R is alkyl of about 10 to about 20 carbon atoms. When R′ and R″ are both CH₃- and R is alkyl averaging about 12 carbon atoms, the structure for dimethyldodecylamine oxide, a particularly preferred amine oxide, is obtained. These amine oxides can be straight or branched chain structures (see U.S. Patent 4,299,313 to Joy) and can be functionalized when desired with various substituent groups, such as hydroxyethyl groups, ethoxylate groups and the like, which are compatible with the cleanser system and will provide the properties desired. Representative examples of these particular type of bleach-stable nonionic surfactants include the dimethyldodecylamine oxides sold under the trademark Ammonyx LO by Stepan Chemical Company, Chicago, ILL. Yet other preferred amine oxides are those sold under the trademark Barlox, by Baird Chemical Industries, Inc. Still others include the Conco XA series, sold by Continental Chemical Company, the Aromax series sold by Armour Industrial Chemical Company, the Schercamox series, sold by Scher Brothers, Inc., the Synprolam series sold by ICI Americas Inc., and specialty amine oxides sold by Ethyl Corporation. These amine oxides preferably have main alkyl chain groups averaging about 10 to 20 carbon atoms. Other types of suitable surfactants include amphoteric surfactants, exemplary of which are betaines, imidazolines and certain quaternary phosphonium and tertiary sulfonium compounds. Particularly preferred are betaines such as N-carboxymethyl-N-dimethyl-N-(9-octadecenyl)ammonium hydroxide and N-carboxymethyl-N-cocoalkyl-N-dimethyl ammonium hydroxide, the latter of which is sold under the trademark Lonzaine by Lonza Corporation. Other acceptable surfactants are the zwitterionic surfactants exemplified in US-A-4,005,029, to Jones, (see columns 11-15) the disclosure of which patent is incorporated herein by reference. It is preferred in some instances to combine at least two of these surfactants, most preferably the anionics and the bleach-stable nonionics. Combinations of these types of surfactants appear to be particularly desired when a bleach is present in the cleanser for maintaining hypochlorite half-life stability at elevated temperatures for long periods of time. Additionally, when these particular combinations of surfactants are combined with the alumina thickener, the formulations thus produced are practically free from syneresis. The surfactant is generally present in the cleanser in a range of 0.1 to 15% by weight, based on the total weight of the cleanser, more preferably 0.5 to 10% and most preferably 1 to 5%. Electrolytes/Buffers The electrolyte/buffer used in the present invention should be selected in combination with the surfactant or surfactants and the colloidal alumina thickener in order to produce the pourable and smooth flowing consistency desired for the composition of the present invention. In broad terms, electrolytes/buffers employed within the present invention are generally the salts of various inorganic acids, including the alkali metal phosphates, polyphosphates, pyrophosphates, triphosphates, tetrapyrophosphates, silicates, metasilicates, polysilicates, carbonates, hydroxides, chlorides, sulfates, and mixtures of the above. Certain divalent salts, for example, alkaline earth phosphate, carbonate, hydroxide, etc., salts can function singly as buffers. If such compounds were used, they normally would be combined with at least one other of the previous electrolytes/buffers to provide the appropriate pH adjustment. It may also be desirable to use as a buffer such materials as aluminosilicates (zeolites), borates, aluminates and bleach-stable organic materials such as gluconates, succinates, maleates, and their alkali metal salts. These electrolytes/buffers function to maintain the pH range of the inventive cleanser compounds preferably above 7.0, more preferably above 8.0 or 9.0 and most preferably at between about 10.0 and 13.0. The amount of electrolyte/buffer employed with the composition of the present invention can vary from 0.1% to 15% by weight of the cleanser, preferably from 0.5 to 10% and more preferably from 1 to 5%. The silicate electrolyte/buffers useful in the present invention are formed by a combination of sodium oxide and silicon dioxide and may preferably be a sodium silicate having a weight ratio of silicon dioxide to sodium oxide of about 3.75/1 and about 1/1, preferably between about 3/1 and about 1.5/1. More preferably, the electrolyte/buffer is in the form of sodium silicate having a weight ratio of silicon dioxide to sodium oxide of about 2.4/1. A silicate as described above is available, for example, from the PQ Corporation, Philadelphia, PA. Colloidal Alumina Thickener The colloidal alumina thickener component of the present invention is preferably a hydrated aluminum oxide having qualifying characteristics such as particle size to cause it to function as a colloidal thickener. In this sense, the colloidal alumina thickener used in the invention is to be contrasted from abrasive alumina materials having substantially larger particle sizes, for example substantially greater than one micron. Accordingly, the particle size of the colloidal alumina thickener is a particularly important feature for that component of the invention. It should be noted that, while the discussion herein is in terms of the colloidal alumina being a thickener, a critically important function of the colloidal alumina is to act, in combination with the surfactants and soaps in the cleanser compositions of the present invention, as a suspension or suspending agent for the abrasives and particularly to stably suspend the abrasives to prevent the abrasive from settling out or separating in storage over long periods of time. Preferred hydrated aluminas within the present invention are derived from synthetic Boehmites. Of greater importance, the hydrated colloidal alumina thickener of the present invention is chemically insoluble, that is, it should not dissolve in reasonably acidic, basic or neutral media. However, it is noted that colloidal alumina will dissolve in strongly alkaline media, for example, 50% NaOH. A typical alumina is distributed by Remet Chemical Corp., Chadwicks, N.Y., under the trademark DISPERAL (formerly DISPURAL) and manufactured by Condea Chemie, Brunsbuettel, West Germany. DISPERAL is an aluminum oxide monohydrate which commonly forms stable colloidal aqueous dispersions. Alumina products of this type commonly exist as dry powders which can form thixotropic gels, bind silica and other ceramic substrates, while possessing a positive charge and being substantive to a variety of surfaces. DISPERAL has a typical chemical composition of 90% alpha aluminum oxide monohydrate (Boehmite) 9% water, 0.5% carbon (as primary alcohol), 0.008% silicon dioxide, 0.005% ferric oxide, 0.004% sodium silicate, and 0.05% sulfur. It has a surface area (BET) of about 320 m²/gm, an undispersed average particle size (as determined by sieving) of 15% by weight being greater than 45 microns and 85% being less than 45 microns, an average particle size, in dispersion, of 0.0048 microns as determined by X-ray diffraction, and a bulk density of 721 kg/m³ (45 pounds per cubic foot)(loose bulk) and 801 kg/m³ (50 pounds per cubic foot) (packed bulk). Yet another alumina suitable for use within the present invention, although not as preferred, is manufactured by Vista Chemicals Company, Houston, Texas and sold under the trademark CATAPAL alumina. CATAPAL has a typical chemical composition of 74.2% aluminum oxide (Boehmite), 25.8% water, 0.36% carbon, 0.008% silicon dioxide, 0.005% ferric oxide, 0.004% sodium oxide and less than 0.01% sulfur. It has a surface area (BET) of 280 m²/gm, an undispersed average particle size (as determined by sieving) of 38% by weight being less than 45 microns and 19% being greater than 90 microns. These colloidal alumina thickeners, used in dispersed form in the invention, generally have exceedingly small average particle size in dispersion (i.e., generally less than one micron). In point of fact, the average particle size diameter of these thickeners when dispersed is likely to be around 0.0048 micron. Thus, a preferred average particle size range in dispersion is preferably less than one micron, more preferably less than about 0.5 micron and most preferably less than 0.1 micron. Due to their small particle size, little or substantially no abrasive action is provided by these types of thickeners even though they are chemically insoluble, inorganic particles. Additionally, these colloidal aluminas are chemically quite different from aluminum oxide abrasives, such as corundum. Colloidal aluminas are produced from synthetic Boehmite. In general, they are synthesized by hydrolyzing aluminum alcoholates, with the resulting reaction products being hydrated aluminum (colloidal alumina) and three fatty alcohols. The reaction equation is set forth below: (From Condea Chemie, "PURAL PURALOX DISPERAL High Purity Aluminas" Brochure (1984), the contents of which are herein incorporated by reference.) These hydrated aluminum oxides are called synthetic Boehmites merely because their crystalline structure appears similar to that of naturally occurring Boehmite. Boehmite, which is the actual mineral, has a Mohs hardness of about 3. It thus may be expected that the synthetic Boehmite would not have a hardness greater than the naturally occurring Boehmite. Corundum, on the other hand, appears to have a Mohs hardness of at least 8 and perhaps higher. Thus, any abrasive action provided by colloidal aluminum oxides may be severely mitigated due to their relative softness. An important aspect of the hydrated aluminas used herein is that they should be chemically insoluble, i.e., should not dissolve in acidic, basic or neutral media in order to have effective thickening as well as stability properties. However, colloidal Boehmite aluminas will dissolve in highly basic media, e.g., 50% NaOH. A further important point is that these colloidal alumina thickeners, in order to be useful as thickeners in the cleansers of this invention, must be initially dispersed in aqueous dispersion by means of strong acids. Preferable acids used to disperse these colloidal aluminas include, but are not limited to, acetic, nitric and hydrochloric acids. Sulfuric or phosphoric acids are not preferred. Generally, a 1-50%, more preferably are 5-40%, and most preferably 10-35% dispersion is made up, although in some instances, percentages of colloidal alumina are calculated for 100% (i.e., as if non-dispersed) active content. In practice, the colloidal alumina may be added to water sufficient to make up the desired percent dispersion and then the acid may be added thereto. Or, the acid may be first added to the water and then the colloidal alumina is dispersed in the dilute acid solution. In either case, a substantial amount of shearing (i.e., mixing in a mixing vat) is required to obtain the proper rheology. Usually, a relatively small amount of concentrated acid is added. For instance, for a 25 wt.% dispersion material, 25% alumina monohydrate is combined with 1.75% concentrated (12M) hydrochloric acid and then dispersed in 73.75% water. The colloidal alumina thickener itself is generally present in the cleanser in the range of 1 to 15% by weight based on the total weight of the cleanser, preferably 1 to 10%, more preferably 1 to 6%, and most preferably, 1 to 4.7. Many useful formulations will contain from 2.5 to 3.5% colloidal alumina according to the present invention. Neutralization of the acidified dispersed colloid is necessary to obtain the desired, finished product rheology (i.e., it thickens). Thus, the acidified, diluted colloid is neutralized, preferably by sodium hydroxide (e.g., a 50% solution), although if the electrolyte/buffer is sodium carbonate or sodium silicate, it may be possible to forego the sodium hydroxide as a separate component. Secondly, since a halogen bleach may be added, if desired, to the cleansers of this invention, and such bleaches are unstable in the presence of acid, neutralization is also desirable when a bleach is used. With respect to thickening, it should be noted that while there are many types of inorganic and organic thickeners, not all will provide the proper type of plastic, flowable rheology desired in the present invention, particularly the preferred pourable consistency. Common clays, for instance, those used in US-A-3,985,668 and US-A-3,558,496, will likely lead to a false body rheology. False body rheology pertains to liquids which, at rest, turn very viscous, i.e., form gels. Problematic with such false body liquids is that they appear to tend to thicken very rapidly and harden or set up so that flowability is a problem. A thixotropic rheology is also not particularly desirable in this invention since in the thixotropic state, a liquid at rest also thickens dramatically, but, theoretically, should flow upon shearing. If the thixotrope has a high yield stress value, as typcially found in clay-thickened liquid media, the fluid at rest may not re-achieve flowability without shaking or agitation. As a matter of fact, if colloidal alumina alone is used to thicken the liquid cleansers of this invention, a thixotrope with high yield stress values appears to result. This type of product is less preferred, and therefore, the surfactants included in the formulas of this invention are crucial towards achieving a desired creamy, flowable, plastic rheology, particularly the preferred pourable consistency. Ordinarily, a thixotrope will flow from a dispenser only upon shaking or squeezing. An example of a typical thixotrope is catsup, which sometimes requires quite a bit of shaking and pounding of the bottom of the bottom containing it to induce flow. The type of rheology desired in this invention is a plastic, flowable rheology. This sort of rheology does not require shearing to promote fluidity. Thus, a product made in accordance with the present invention will not require, in its preferred form, squeezing (assuming a deformable plastic squeeze bottle), shaking or agitation to flow out of the container or dispenser, but will have a pourable consistency. In a non-preferred form, the cleansers of the present invention may not be pourable from a particular container, but nevertheless are a smoothly flowable, plastic consistency and are not thixotropes. Attaining this rheology together with the abrasive-suspending stability in the cleansers of the present invention containing organic solvents was very surprising since it has been known that addition of organic solvents to suspended abrasive cleanser compositions would ordinarily be expected to affect the rheology differently and expected to promote syneresis and/or cause the abrasive suspension to be unstable. It was surprising that the colloidal alumina thickened and stabilized cleansers, such as in Choy et al. US-A-4,695,394, would have such plastic rheology and also such abrasive-suspending stability so as to not become unstable when the organic solvents were included in such compositions in accordance with the present invention. Nothing in the art had ever disclosed that alumina thickened suspended-abrasive household hard surface cleansers could contain an organic solvent to enhance cleaning efficacy in some applications. One would have expected the solvent to have detrimental effects on the plastic consistency and/or the abrasive-suspending stability properties of these cleansers. One patent, US-A-3,558,496 had suggested coupling an aluminum oxide with common clays to thicken hypochlorite, but had not indicated that using surfactants instead of the clays would lead to the desired plastic rheology and especially the preferred pourable consistency of the cleansers of this invention. Another, US-A-4,508,634 to Elepaño et al. disclosed the possible use of colloidal alumina as a protective colloid thickener to stabilize an emulsion of surfactants, solvents and an optional mild abrasive, but did not recognize or disclose that a stable suspension of abrasives could be attained with the colloidal alumina in the combination of surfactants, soaps and organic solvents. Fatty Acid Soap The soap useful in the present invention can be straight chain or branched chain fatty acids having 6 to 24 carbon groups with univalent or multivalent cations which render the soap soluble or dispersible in the aqueous cleanser. The soap may be an alkali metal salt of such a fatty acid, such as Li, Na or K, or may be ammonium or alkylammonium salts thereof. Soaps which are conventionally used as suds suppressors will generally be useful in the present invention. While soaps are selected for use in prior art cleansers for either suds control or for bleach stability, it is also important in the present invention that the soap be compatible with and solubilize the organic solvent in the cleanser of the present invention, and also be compatible with the colloidal alumina thickener in the cleanser of the present invention. The soap which may be saturated or unsaturated, provides in combination with the alumina colloid thickener and hydrocarbon solvent, the characteristics of improved cleansing properties and the improved resistance to syneresis, while still maintaining the plastic consistency or plastic consistency or pourable flow characteristics of the cleanser of this invention. As indicated above relative to the surfactants, a saturated soap is usually preferred when a bleach is present in order to maintain bleach stability, but an unsaturated soap may be preferred in some instances when a bleach is not included in the cleanser of the present invention. The soap useful in the present invention is generally limited to a molecular weight range characterized by having from about 8 to about 20 carbon groups, either in a straight or branched chain configuration. More preferably, the soap is of a type having from about 10 to about 18 carbon groups, even more preferably about 12 to about 14 carbon groups. The amount of soap employed in a cleanser according to the present invention will be from 0.1 to 5% by weight of the cleanser, preferably from 0.5 to 4% and most preferably up to 3%. Suitable fatty acid soaps useful in the present invention may be selected from the class consisting of potassium laurate, sodium laurate, sodium stearate, potassium stearate, sodium oleate, etc. Similar soaps containing ammonium ion as a cation may also be used particularly if the cleanser does not contain a bleach. Suitable soaps for use within the present invention are disclosed in Chemical Publishing Co., Inc., Encyclopedia Of Surface-Active Agents, Vol. I (1952), page 39 etc., Kirk-Othmer, Encyclopedia of Chemical Technology 3d, Vol. 21 pp. 162-181 re "Soaps" and Vol. 22, re "Surfactants". Accordingly, those references are incorporated herein as though set out in full. The manner in which the fatty acid anionic surfactant or soap functions in combinations with the colloidal alumina thickener and the hydrocarbon solvent according to the present invention is not fully understood. It is believed that the soap may be useful for reasons described below. However, the present invention is not to be limited by the following theory. Initially, it is not merely the anionic form of the soap that makes it useful within the present invention since other anionic surfactants have been tested without achieving the same advantages. The soaps herein appear, overall, to be more hydrophobic in nature than other anionic surfactants. While not being entirely understood, this more hydrophobic nature of the soaps surprisingly appears to help maintain in the organic solvent containing system of this invention the uniform smoothly flowable characteristics and advantageously promotes the smoothly flowable plastic rheology, as well as the preferred pourable consistency, of the cleansers of the present invention. In further supposition, it is also noted that the soap has been particularly effective in combination with colloidal alumina thickener where the cleanser also contains a silicate based material as an electrolyte/buffer. In this regard, it is theorized that the silicate and alumina may function to form a network, possibly through the formation of bridging oxygens, in order to produce a very thixotropic composition similar to compositions employing clay as a thickening agent. It is believed that soap, having a carboxyl group which is hydrophilic in combination with a hydrophobic alkyl chain functions to break up the network formed between the silicate and alumina in order to render the composition smoothly flowable, as realized by the present invention. It is also believed that the soap also aids in solubilizing the organic solvent present in the cleansers of the present invention because it probably helps to mix or emulsify the solvent therein. Organic Solvents The organic solvents useful in the present invention are alkyl or aryl hydrocarbons containing at least 2 carbon atoms, preferably about 4 to about 18 carbon atoms, and can include ethers, alcohols, esters, ketones and other hydrocarbons which are compatible with the fatty acid soap surfactant and colloidal aluminum present in the composition of the cleanser of the present invention. Examples of such organic solvents include d-limonene, terpinolene, pine oil, glycol ethers such as butoxyethanol (butyl "Cellosolve"), straight or branched chain C₄ glycol ethers; glycols, such as polyethylene glycol; alcohols such as phenol, ethyl alcohol, benzyl alcohol, geraniol, citronellol, santalol, menthol, borneol, carveol, ethylhexelcarbonyl, vetiverol, linalol, terpineol, myrcenol, cetrol; and esters such as linalyl acetate, benzyl acetate, isobornyl acetate, ethyl acetoacetate and isoamylacetate. Other examples of organic solvents which may be useful in the cleansers of the present invention include saturated derivatives of terpenes, isoprenes, mineral spirits, such as the Isopar and Norpar series of mineral spirits and mineral oils sold by Exxon Corporation, and mineral oils, such as available from Penreco Company. Of course, mixtures of various organic solvents are useful in the cleansers of the present invention. As understood with respect to the surfactants and soaps, saturated organic solvents should be used when a bleach is included in the cleansers of this invention to promote bleach stability as recognized by those skilled in the art. Conversely, unsaturated organic solvents may be selected for use in the non-bleach formulations of the cleansers of this invention. Moreover, it is further understood that the organic solvent is selected to be compatible with the soap and surfactant useful in the present invention as outlined above. The amount of organic solvent employed in the cleanser according to the present invention will be from 0.1 to 10% by weight of the cleanser, preferably from 0.1 to 8%, more preferably from 0.1 to 7%, even more preferably from 0.1 to about 6%, and most preferably up to 4%. In addition, it appears desirable in the present invention that the ratio of organic solvent to the combined amount of soap and surfactant generally be within certain ranges for most practical formulation. In general, the weight ratio of organic solvent to soap plus surfactant should be less than about 1:40, and usually between about 10:1 and about 1:20, preferably between about 2:1 and about 1:10, more preferably between about 1:1.5 and about 1:9, still more preferably between about 1:2 and about 1:8, and most preferably between about 1:3 and about 1:7. Other Ingredients As mentioned above, the cleansers of the present invention can, when desired, contain a bleach. A source of bleach is selected from various halogen bleaches. For the purposes of the present invention, halogen bleaches are particularly favored. As examples thereof, the bleach can be selected from the group consisting essentially of the alkali metal and alkaline earth salts of hypohalite, hypohalite addition products, haloamines, haloimines, haloimides and haloamides. These also produce hypohalous bleaching species in situ with hypochlorites being a preferred form of bleach. Representative hypochlorite producing compounds include sodium, potassium, lithium and calcium hypochlorite, chlorinated trisodium phosphate dodecahydrate, potassium and sodium dichloroisocyanurate, trichloroisocyanuric acid, dichlorodimethyl hydantoin, chlorobromo dimethylhydantoin, N-chlorosulfamide, and chloramine. As noted above, a preferred bleach employed in the present invention is sodium hypochlorite having the chemical formula NaOCl, in an amount ranging from about 0.1% to about 5%, more preferably about 0.25% to 4% and most preferably 0.5% to 2.0%. The purpose for the bleach is evident in forming an oxidizing cleaning agent which is very effective against oxidizable stains such as organic stains. A principal problem with the use of bleach in such compositions is its tendency to be unstable or to cause instability of other components, particularly certain surfactants if they are present in substantial amounts. In any event, because of the use of colloidal alumina as a thickener in the present invention together with a fatty acid soap, a surfactant, and organic solvent together with only limited amounts of additional surfactant components, the bleach stability of the composition of the present invention (expressed in half-life stability) is surprisingly good resulting in a product capable of maintaining excellent flow characteristics and bleach strength even after considerable periods of shelf life. In addition to the components for the cleaning composition of the present invention as set forth above, further desirable adjuncts may include bleach-stable dyes (for example, anthraquinone dyes), pigments (for example, phthalocyanine, TiO₂, ultramarine blue), colorants and fragrances in relatively low amounts, for example, about 0.001% to 5.0% by weight of the cleanser composition. Water Water is the medium used as the continuous phase in which the various components of the cleanser of the present invention are dissolved, dispersed or suspended. Some of these components may be added to the cleanser in a water base, thus contributing to the total water present in the cleanser. While water and the miscellaneous minor ingredients or additives make up the remainder of the composition, water is generally present in amounts ranging from 10-80% by weight of the cleanser. Method of Preparing A preferred method of preparing the liquid cleanser of this invention comprises combining: (a) an initial portion of the total water with a colloidal aluminum oxide thickener; (b) a final portion of the total water and a discrete amount of a neutralizing agent; (c) optionally, a halogen bleach; (d) abrasives; (e) a fatty acid soap; (f) a surfactant (bleach stable nonionic when a bleach is used); (g) a buffer/electrolyte which interacts with the surfactants recited in steps (e) and (f) and the thickener recited in step (a) to result in a plastic rheology; and (h) an organic solvent. As similarly described in US-A-4,657,692 at column 13 (the disclosure of which patent is incorporated herein by reference) to produce the cleanser, alumina is charged into a vat or suitable mixing vessel which has been provided with a suitable mixing means, such as an impeller, which is in constant agitation with suitable angular velocity. The alumina is acidified and diluted with about 50% of the total water used. An alkyl benzene sulfonate phase stabilizer can be optionally added at this point. Next, a neutralizer, such as a 50% NaOH solution can be added, with the remainder of the water. Next, halogen bleach and abrasives can be added. Thereafter, the anionic surfactants are added. When silicate is used as the electrolyte/buffer, it is necessary to have a fatty acid soap as one of the anionic surfactants since, as explained in US-A-4,695,394, the soap appears to surprisingly break up any network which could form between the silicate and the colloidal alumina. Next, the bleach-stable nonionic surfactant is added, which is generally a trialkyl amine oxide (although a betaine or other surfactant would likely be suitable). At this point any alkyl benzene sulfonate is most preferably, although optionally, added. The electrolyte/buffer is then added and finally, the organic solvent is added. Alternatively, the organic solvent can be premixed with the surfactants if desired in some methods of making the cleansers of the present invention. Note that at virtually any step in this method, the optional minor ingredients, such as fragrance and pigments could be added. However, since fragrance is an organic component which may be more susceptible to oxidation by the halogen bleach, it is preferable to add it last. The invention is further demonstrated by the examples and results set forth below. Examples 1 - 9 The following cleansers were prepared and tested for properties as shown: EXAMPLES 10 and 11 Greasy/Oily Soil Removal Test Kitchen grease soil was applied on marlite test panels. Three grams of each product was applied to a sponge dampened with 100ppm hardness (3:1 Ca:Mg ratio). A Gardner Wear-Tester was used to move the sponge across a soiled panel. The number of cycles required for complete removal was noted. (One back and forth stroke of the Tester equals one cycle.) The most effective cleaning products required fewer cycles to remove the soil. Ex. Product Cycles for Complete Removal 10 Formula 4 (from above) 6 11 Mr. Clean Cleanser (Commercially available from Procter and Gamble Co., Cincinnati, Ohio, U.S.A. 7 EXAMPLES 12 - 16 The following bleach containing cleansers were prepared and tested for syneresis as shown: Formula DISPERAL Alumina NaOCl Solvent Syneresis 1F/T 24days @ 49°C (120°F) 12 2.75% 1.1% dihydroterpineol 24.6% 7.3% 13 2.75% 1.1% pimenthane 26.5% 3.5% 14 2.75% 1.1% pimane 29.6% 5.4% 15 2.75% 1.1% pimenthane/cineole 27.9% 3.5% 16 2.75% 1.1% pinane/isocamphane 28.4% 3.6% EXAMPLES 17 AND 18 The following embodiments illustrate formulations containing low and high levels of abrasive. Material Formula 17 Low Abrasive Wt. % Formula 18 High Abrasive Wt. % Water 66.06 22.66 HCl (38%) 0.21 0.09 Disperal 4.50 2.00 Calcium Carbonate Abrasive 5.00 55.00 Pigment 0.75 0.75 Tergitol 2.70 1.71 LAS 2.80 1.78 SAS 2.65 1.68 Soap Solution 7.33 7.33 Sodium Chloride 2.00 2.00 Terpinolene 3.00 2.00 Silicate RU 3.00 3.00 100.00 100.00 Viscosity (cps)[mPa.s] 1,720 5,920 The present invention also contemplates methods for forming cleansers including compositions such as those described above and illustrated by the various examples. Generally, such a method comprises the steps of combining the various components to form the cleanser composition. The present invention also contemplates methods for cleaning hard surfaces or removing soil in a manner believed obvious from the preceding description. However, to assure a complete understanding of the invention, such a method is carried out by contacting the surface, stain or soil with a composition according to the present invention. Thereafter, the composition together with the suspended stain is preferably removed from the surface by rinsing. Accordingly, there has been disclosed above a number of embodiments and examples for a thickened aqueous abrasive cleanser particularly characterized by a smoothly flowable or plastic consistency while demonstrating the ability to suspend solids, preferably in the form of abrasives. While preferred embodiments and examples of the invention have been illustrated and described above, it is to be understood that these embodiments are capable of further variation and modification; therefore, the present invention is not to be limited to precise details of the embodiments set forth above but is to be taken with such changes and variations as fall within the purview of the following claims.

Claims: A thickened aqueous hard surface abrasive scouring cleanser characterized by being smoothly flowable or plastic and being stably abrasive-suspending, comprising: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of the cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. The cleanser of claim 1 wherein the colloidal alumina thickener has a maximum particle size in dispersion of not more than 0.1 micron. The cleanser of claim 1 wherein the surfactant comprises an anionic surfactant. The cleanser of claim 1 wherein the fatty acid soap is an alkali metal fatty acid soap. The cleanser of claim 3 wherein the anionic surfactant is monovalent. The cleanser of claim 1 wherein the organic solvent is at least one of d-limonene, terpinolene, pine oil, a glycol ether, an alcohol or a mixture thereof. The cleanser of claim 1 wherein the fatty acid soap comprises from 0.1 to 4% by weight of the cleanser. The cleanser of claim 1 wherein the organic solvent comprises from 0.1 to 7% of the cleanser. The cleanser of claim 1 further comprising a hypochlorite bleach. The cleanser of claim 1 characterized by being pourable. A method for preparing a thickened aqueous hard surface abrasive scouring cleanser having a smoothly flowable or plastic consistency comprising the step of combining: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of the cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than one micron, the colloidal alumina thickener forming from 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser. A method for cleaning a surface with a thickened, aqueous abrasive scouring cleanser characterized by a smoothly flowable or plastic consistency, comprising contacting the surface having a stain thereon with the thickened, aqueous abrasive cleanser comprising: (a) a particulate abrasive having an average particle size greater than one micron to provide scouring action wherein the particulate abrasive comprises from 5 to 70% by weight of the cleanser; (b) at least one of a non-soap type of anionic, nonionic, amphoteric or zwitterionic surfactant being present in a range of 0.1 to 15% by weight of the cleanser; (c) an electrolyte/buffer forming 0.1 to 15% by weight of the cleanser; (d) a colloidal alumina thickener having an average particle size, in dispersion, of no more than about one micron, the colloidal alumina thickener forming from 1 to 15% by weight of the cleanser; (e) a fatty acid soap being present from 0.1 to 5% by weight of the cleanser; and (f) an organic solvent present from 0.1 to 10% by weight of the cleanser.

Inventors: CHOY CLEMENT K, GARABEDIAN ARAM JR, KEEN FREDERICK I, CHOY, CLEMENT K., GARABEDIAN, ARAM, JR., KEEN, FREDERICK I.
Applicants: CLOROX CO, THE CLOROX COMPANY
Application year: 1989
Main classification: C11D3
IPC codes: C11D3, C11D10, C11D17