GB2326884A - Aqueous thickened bleach containing compositions - Google Patents

Description

IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOSITIONS The present invention relates to improved thickened aqueous bleach containing compositions which contain abrasives.

As is known to the relevant art, it is particularly difficult to produce aqueous bleach stable, thickened abrasive cleaning compositions which offer the simultaneous benefits of: good bleach stability which provides an acceptable shelf life for a product; acceptable viscosity characteristics; relatively low cost; and of course efficacy in removing stains and in effectively disinfecting surfaces, especially on inclined hard surfaces such is tiled, enameled and porcelain surfaces such as are typically associated with bathrooms. While the art provides a number of such compositions directed to satisfying these requirements, these compositions have not uniformly met with success. The present invention overcomes may of these shortcomings in the prior art.

The inventive composition is a stable, single phase, thickened bleach containing composition capable of adhering to vertical or inclined surfaces longer than thinner compositions. The composition is an effective agent for stain and soil removal as well as disinfection. The high level of bleach stability and single solution phase behavior of the composition enables the composition to have an acceptable shelf life.

The improved thickened aqueous bleach containing compositions according to the present invention are aqueous compositions which comprise in parts by weight (based on the total weight of the composition): 0.5 - 5.0 of an alkali metal carboxylate, preferably a alkali metal soap such as sodium stearate; 0.25 - 6.0 of a water dispersible nonionic amine oxide; 0.5 - 8.0 of a water dispersible anionic surfactant system including one or more sulfate or sulfonate surfactants, which most preferably includes a minor amount of an alkyl diphenyl ether disulfonate surfactant; 0.5 - 4.0 of an alkali metal salt, preferably an alkali metal chloride; 0.1 - 10.0 of an pH adjusting agent for maintaining the alkalinity of the composition; 0.01 - 10.0 of available chlorine in a bleach releasing material, such as an alkali metal hypochlorite; 1.0 - 50 of an abrasive material, preferably a particulate abrasive material; optionally but desirably, 0.05 - 3.0 of an detergency builder, and, water, in quantunl szffident to provide 100 %wt. of the inventive compositions.

The inventive compositions are alkaline in character, desirably having a pH of about 12 or more, exhibit very favorable viscosity characteristics, are good hard surface cleaners and feature good bleach stability over time. The compositions may also include minor amounts, generally not more than at total of 5% of one or more optional constituents including ones which may improve the aesthetic appeal of the compositions, viz., perfumes and colorants. Such optional constituents should not undesirably affect the shelf stability or rheology of the compositions.

The compositions include alkali metal fatty carboxylate constituent, include sodium, lithium, potassium or ammonium carboxylates, preferably linear C16 - C24 carboxylates. Most preferably Cl 8 - C20 carboxylates are used, and especially the sodium salts of such carboxylates which are effective, and are available at a relatively low cost. A particularly preferred alkali metal soap is sodium stearate.

The inventive compositions also include a nonionic amine oxide constituent.

Exemplary amine oxides include: A) Alkyl di (lower alkyl) amine oxides in which the alkyl group has about 10-20, and preferably 12-16 carbon atoms, and can be straight or branched chain, saturated or unsaturated. The lower alkyl groups include between 1 and 7 carbon atoms.

Examples include lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, and those in which the alkyl group is a mixture of different amine oxide, dimethyl cocoamine oxide, dimethyl (hydrogenated tallow) amine oxide, and myristyl/palmityl dimethyl amine oxide; B) Alkyl di (hydroxy lower alkyl) amine oxides in which the alkyl group has about 10-20, and preferably 12-16 carbon atoms, and can be straight or branched chain, saturated or unsaturated. Examples are bis(2-hydroxyethyl) cocoamine oxide, bis(2-hydroxyethyl) tallowamine oxide; and bis(2-hydroxyethyl) stearylamine oxide; C) Alkylamidopropyl di(lower alkyl) amine oxides in which the alkyl group has about 10-20, and preferably 12-16 carbon atoms, and can be straight or branched chain, saturated or unsaturated. Examples are cocoamidopropyl dimethyl amine oxide and tallowamidopropyl dimethyl amine oxide; and D) Alkylmorpholine oxides in which the alkyl group has about 10-20, and preferably 12-16 carbon atoms, and can be straight or branched chain, saturated or unsaturated.

Preferably the amine oxide constituent is an alkyl di (lower alkyl) amine oxide as denoted above and which may be represented by the following structure:

wherein each: R, is a straight chained Cl-C4 alkyl group, preferably both R, are methyl groups; and, R2 is a straight chained Clo-Cl4 alkyl group, preferably is a C12 alkyl group.

Most preferably the amine oxide constituent is lauryl dimethyl amine oxide.

The compositions include an anionic surfactant system which desirably includes one or more anionic sulfates and, or sulfonates selected from primary or secondary alkyl sulfates, alkyl ether sulfbnates, and most desirably include a minor, but effective amount of one or more diphenyl disulfonates. Each of these materials are commercially available as surfactants and are frequently provided in a salt form in an aqueous carrier.

Exemplary useful alkyl sulfates include those according to the formula:

wherein R is an alkyl chain having from about 8 to about 18 carbon atoms, which may be saturated or unsaturated, and where the longest linear portion of the alkyl chain is 15 carbon atoms or less on the average, M is a counterion, such as an alkali metal, ammonium or substituted ammonium cation, and x is from 0 to about 4.

A particularly useful primary alkyl sulfate is sodium lauryl sulfate A particularly useful secondary alkyl sulfate are those according to the general structure:

where: n, m are each separately number of from 1 - 18 inclusive, and more desirably n and mare each selected such that n + m is a number of from 10 - 14 inclusive; and, X represents a counterion, desirably an alkali metal or ammonium counterion, yet more desirably is lithium, potassium or sodium, especially sodium.

There materials are commercially available under the trade name HOSTAPUR SAS from Höchst AG (Germany) of which various technical grade aqeuous mixtures are presently commercially available.

Alkyl ether sulfates which are desirably included in the inventive compositions include those according to the general structure:

wherein: X represents a counterion, desirably an alkali metal or ammonium counterion, yet more desirably is lithium, potassium or sodium, especially sodium; R represents a hydrophobic alkyl group, desirably a linear or branched C6-C16 alkyl group which may be straight chained or branched, may be optionally substituted but desirably is an unsubstituted linear straight chained C,0 - C14 alpha olefins, and especially is C,2 alpha olefin; n is a number of from 1 - 8 inclusive, but desirably is from 2 - 3 inclusive.

The inventors have surprisingly found that the inclusion of a minor, but effective amount of one or more alkyl diphenyl ether disulfonates advantageously improves the rheological characteristics of the compositions subsequent to accelerated aging testing, which is a useful approximation of shelf life. At the same time presence of these anionic compounds does not undesirably effect either the bleach stability of the compositions, and at least equally importantly do not undesirably solubilize the other constituents and thereby decrease the viscosity or thixotropic characteristics of the inventive compositions subsequent to such accelerated aging testing.

Particularly useful alkyl diphenyl ether disulfonates are commerically available in anionic surfactant compositions from the Dow Chemical Co. under the trade designation DOWFAX, of which those which conform to the following general structure are particularly useful:

wherein: X represents a counterion, desirably an alkali metal or ammonium counterion, yet more desirably is lithium, potassium or sodium, especially sodium, and, R represents a hydrophobic alkyl group, desirably a linear or branched C6-C,6 alkyl group which may be straight chained or branched, may be optionally substituted but desirably are unsubstituted C6-C,2 straight chained alpha olefins, or is tetrapropylene.

Of these, particularly useful are those available as DOWFAX 3B2 which is described as being a sodium salt according to the general structure depicted above and wherein R is a C6 olefin; and, DOWFAX 2Al which is described as being a sodium salt according to the general structure depicted above and wherein R is tetrapropylene.

The individual constituents described above are available from a variety of commercial suppliers, often as technical grade mixtures of the recited compounds, which are frequently provided in a salt form, and are typically supplied in a liquid carrier such as water and/or an organic solvent.

One or more alkali metal salts are included in the inventive compositions as it has been observed that such materials favorably improve the thickening of the compositions. The alkali metal salt may be selected from any number of water-soluble alkali metal salts and mixtures thereof, with the alkali metal preferably defined as lithium, potassium, or sodium, and the anion ion preferably defined as a halide (such as chloride, fluoride, bromide, iodide, and so on). More preferably, the alkali metal salt is selected from the group consisting of sodium chloride, lithium chloride, potassium chloride, and mixtures thereof. For purposes of cost and availability, the alkali metal salt most favored is sodium chloride and may be used in varying amounts to reduce alkali metal hypochlorite degradation, limited only by the avoidance of a "salting out" of the solution (where the surfactants become insoluble in water). The "salting out" phenomenon is well-known to those skilled in the art, as described, for example, in an article by P. Muketjee in J. ofPlzysical Chemistry, Vol. 69, No. 11, p.

4038 (1965) (hereby incorporated by reference) and references cited therein.

As the pH adjusting agent for maintaining the alkalinity of the composition, an alkali metal hydroxide is the preferably used. It is to be understood however, that other known art pH buffers may be employed as long as the stability and viscosity of the composition are not adversely affected, inter alia, carbonate buffers. The alkali metal of the preferred hydroxide may be lithium, potassium, or sodium, and sodium hydroxide and potassium hydroxide are particularly useful pH stabilizers due to cost and availability, with sodium hydroxide most preferred. The alkali metal hydroxide is included in the composition in an effective amount to adjust the composition to a pH level of at least about 11, more preferable from 12 to 13.5, and most preferably within the range from 12 to 13.

The inventors have also found that the compositions desirably include a minor but effective amount of a detergency builder constituent. Examples of such, materials include known detergency builders of the organic or inorganic type may be desirably included in the present inventive compositions. Exemplary detergency builders include alkali metal carbonates (including bicarbonates, and sesquicarbonates), phosphates, polyphosphates and silicates. More specific examples include sodium tripolyphosphate, sodium carbonate, potassium carbonate, sodium polyphosphate, potassium pyrophosphate, potassium tripolyphosphate, and sodium hexametaphosphate.

These materials may be used singly, or in mixtures, and may also be used in conjunction with sequestrants such as organic builder salts. By way of non-limiting example such include alkali metal polycarboxylates including water-soluble citrates such as sodium and potassium citrate, sodium and potassium tartarate, sodium and potassium ethylenediaminetetraacetate, sodium and potassium N-(2-hydroxyethyl)ethylene diamine triacetates, sodium and potassium nitrilo triacetates, as well as sodium and potassium tartrate mono- and di-succinates. As noted, these organic builder salts may be used individually, as a combination of two or more organic builder salts, as well as in conjunction with one or more detergency builders, including those indicated above.

Desirably, a minor amount of an alkali metal metasilicate or orthosilicate, especially sodium metasilicate is present in the inventive compositions, as it has been observed by the inventors that such are effective and do not deleteriously effect the bleach stability or viscous characteristics of the inventive compositions described herein. In place of, or in addition to the preferred sodium metasilicate, sodium periodate may also be very advantageously used with similar beneficial effect.

As the bleach releasing material, hypochlorites such as alkali metal hypochlorites, as well as hypochlorite precursors may be used in the compositions. A preferred material is sodium hypochlorite which is effective, and widely commercially available.

The compositions include abrasive material, preferably a particulate abrasive material such as any of a variety of dispersible particulate solids including but not limited to inorganic materials such as: carbonate salts including alkali metal carbonates, alkali metal bicarbonates and alkali metal sesquicarbonates; calcite, dolomite, feldspar, diatomaceous earth, talc, bentonite, pumice, alumina, silica which and, oxides such as aluminum and titanium oxides. Other abrasive materials based on organic polymers may also find use in the inventive compositiosn, especially those in finely comminuted or particulate form. Such materials may be used singly or in combination. Desirably these abrasive materials are comminuted materials, with an average particle diameter falling within the range of from about 0.1 - 500 micrometers, more desirably fall within the range of from about 1 - 50 micrometers, and most desirably fall within the range of from about 5 to about 15 micrometers.

The inventive compositions are viscous in nature, and desirably exhibit a viscosity of between about 500 and 4000 cps, and more desirably from 700 to 2000 cps at a temperature of 25"C as measured using a Brookfield RVT viscometer using a No.3 spindle at a speed of 50 rpm. It is to be noted that the viscosity of a newly made composition is frequently less viscous than subsequent to aging, and that the compositions may exhibit thickening upon standing or storage over extended periods of time, such as 3 - 6 months. Such thickening however is not considered to be deleterious to the overall performance of the composition, as it has also been observed that the composition taken on thixotropic characteristics and may be easily rendered flowable by simply agitating the composition, such as by briefly shaking the container containing the composition.

The compositions also exhibit excellent synerersis characteristics as exhibiting almost no separation of the constituents.

According to the invention, the alkali metal hypochlorite composition is not only viscous, but also exhibits an acceptable shelf-life both in terms of retardation of alkali metal hypochlorite degradation and single solution phase behavior. In the inventive composition, the alkali metal hypochlorite degradation has been slowed to render a composition having an alkali metal hypochlorite half-life of at least about 30 days, more preferably at least three months and most preferably at least six months.

Sypochlorite degradation may be measured by alkali metal hypochlorite titration over time (which may be accomplished by numerous techniques known to those skilled in the art). Observation of the single solution phase behavior of the composition may be made visually. The high level of stability combined with the high level of viscosity provides for a commercially desirable composition useful as a multi-purpose cleaning composition.

The high viscosity characteristic of the composition makes it particularly wellsuited for use as a hard surface cleaner and disinfectant, such as, a bathroom cleaner, a toilet bowl cleaner, a mold and mildew cleaner, a laundry additive, and so on.

Additional optional ingredients include suitable hypochlorite-stable colorants, perfumes, perfume blends, and so on, as known to those skilled in the art.

Any number of techniques may be employed to prepare the inventive composition, as within the knowledge of one skilled in the art.

The compositions according to the invention are desirably produced utilizing a high shear mixer which ensures that a homogenous composition is produced. Such mixing conditions, where high shear is developed ensures the optimum mixing conditions. One such mixing device includes a conventional variable speed, electrically operated stirrer equipped with a high speed dispersion stirrer, such as a Cowles blade. Such a Cowles blade desirably includes a surface coating which does not undesirably react with any of the constituents used to form the inventive compositions.

While the order of the addition of the constituents may vary, it is desired that a quantity of the final amount of water is preheated to sufficiently solubilize the anionic and nonionic amine oxide The invention is further illustrated in the following non-limitative examples in which weight percentages are by total weight of the final composition unless otherwise indicated.

Examples A number of compositions illustrative of compositions according to the invention were produced. The formulations are listed in Table 1, and the order of producing the compositions are described below. The constituents indicated on Table 1, are the respective weights (actives weight) of the named chemical compound. The commercial source, and weight percentage of actives of a respective chemical compound is indicated on Table 2, following. Where no weight percentage of actives indicated in Table 2, it is presumed that the constituent is comprised of "100%wt." actives.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Sodium stearate 1.25 1.0 1.25 1.0 1.0 lauril dimethyl amine oxide 2.5 1.5 2.5 1.5 1.5 Sodium lauryl ether sulfate --- 1.5 1.25 --- 1.5 Sodium lauryl sulfate 1.25 --- --- 1.5 -- Sodium sulfate 0.25 --- --- --- -- Secondary alkyl sulfonate --- 1.0 0.25 1.0 1.0 Diphenyl disulfonate --- --- 0.10 0.1 0.1 Sodium chloride 0.75 0.75 0.75 0.75 0.75 Sodium metasilicate 1.0 1.0 1.0 1.0 1.0 Sodium hydroxide 0.5 0.5 0.5 0.5 0.5 Calcium carbonate 12.0 12.0 12.0 12.0 12.0 Sodium hypochlorite 20.0 20.0 20.0 20.0 20.0 Perfume 0.01 0.01 0.01 0.07 0.07 Deionized water q.s. q.s. q.s. q.s. q.s.

The source of the constituents denoted on Table 1, above is described and detailed in Table 2, following: TABLE 2 sodium stearate (Chemserve Fine Chemicals) lauryl dimethyl amine oxide EMPIGEN OB (30%wt. actives) (Albright & Wilson Co.) sodium lauryl ether sulfate EMPICOL ESB3 (28% wt. actives) (Albright & Wilson Co.) sodium lautyl sulfate EMPICOL Lx28R (28% wt. actives) (Albright & Wilson Co.) sodium sulfate (Protea Industrial Chemicals) secondary alkyl sulfonate HOSTAPUR SAS 60 (60% wt actives) (Hoechst AG) diphenyl disulfonate an alkyl diphenyl ether disulfonate (45% wt actives) DOWFAX 3B2 (Dow Chemical Co.) sodium chloride (Sunsalt) sodium metasilicate (Protea Industrial Chemicals) sodium hydroxide Anhydrous, pellet form; (Protea Industrial Chemicals) calcium carbonate Average particle size, 15 microns; KULUBRITE 15 (G & W Base) sodium hypochlonte (7.5%wt. actives)(NCP Chlorchem) perfume Proprietary composition of its manufacturer deionized water Deionized water Each ofthe compositions according to the examples were produced generally in accordance with the following protocol: First, approximately 60% of the total water used to make the formulation was heated to within a few degrees above 80"C and poured into a clean 2 litre beaker.

Next, a variable speed, electrically operated stirrer equipped with a coated Cowles blade was placed in the water and stirring was initiated. The speed of blade rotation was set'at a slow speed (approx. 150 - 200 rpm). Next the sodiurn stearate was slowly added in a dropwise or slow stream manner such that undue aeration /foam formation and partial solubilization was minimized. The temperature was maintained at about 75 - 80 OC during and after the addition of the stearate, and stirring continued until the sodium stearate completely dissolved.

Thereafter, the lauryl dimethyl amine oxide was added by slowly pouring it into the beaker. Stirring continued at the same speed as before, and continued until the solution was homogeneous. Next, each of the anionic surfactant constituents were added individually, pausing between each addition for sufficient time such that the mixture became homogenous. Generally subsequent to the addition of the anionic surfactants the mixture appeared to be translucent or opaque.

The remaining volume of water was dispensed into a separate small beaker.

To the beaker, the sodium chloride was added and mixed using a further electrically operated stirrer until the sodium chloride was fully dissolved. Thereafter this solution was slowly poured into the two litre beaker and the mixing continued until a homogenous mixture was once again formed. It was observed that due to this addition, thickening of the mixture occurs and an increase in the rotational speed of the Cowles blade may be made in order to maintain the initial agitational requirement.

While stirring continued, the contents of the beaker were allowed to cool to within a few degrees below 30"C. During this cooling process care should was taken to monitor and if necessary adjustments were made to the rotational speed of the Cowles blade such that the breakup of the filamentous network formed during the cooling process was avoided.

In a further clean beaker, the sodium hypochlorite, sodium hydroxide and sodium metasilicate are mixed to homogeneity. After the contents of the 2 liter beaker were sufficiently cooled as above the mixture of the sodium hypochlorite, sodium hydroxide and sodium metasilicate were added thereto while stirring continuted. At this point, a further thickening of the mixture was observed and again, if necessary the rotational speed of the Cowles blade was adjusted to avoid the breakup of the filamentious network formed. At the same time, care was taken to maintain the temperature of the composition to avoid crystallization of the anionic soap, and its precipitation from the mixture. Stirring of the mixture was maintained to ensure homogeneity thereof, typically for a period of approximately 20 mintutes.

Thereafter, the abrasive material was slowly added to the mixture and the speed of the Cowles blade was increased by approximately 75 - 100%, and thereafter was returned to the prior rotational speed which had been set just prior to the addition of the abrasive material. The mixture was stirred to homogeneity, after which the stirrer was deactivated and removed. The resulting compositions were thickened mixtures which were homogenous in appearance, and smooth in texture.

Evaluation of Chlorine Stabilitv: Certain of the examplary compositions were evaluated for chlorine stability under accelerated aging conditions over a period of weeks. In the test, the initial available chlorine content was determined by %C12 by the sodium thiosulfate method, and again determined at periodic intervals over the duration of the test. The samples of the compositions were maintained at elevated temperatures of 40"C for a ten week period, and testing was performed at weekly intervals. The following Table 3 lists the average available chlorine readings over the duration of the test.

TABLE 3 Example I Initial 1.71 1 week 1.61 2 weeks 1.57 3 weeks 1.48 4 weeks 1.39 5 weeks 1.36 6 weeks 1.31 7 weeks 1.28 8 weeks 1.24 9weeks 1.17 10 weeks 115 net % loss of - 32% available chlorine As may be seen from the results of Table 3, the compositions exhibited excellent retention of available chlorine over the duration of the accelerated aging test.

It was observed that during the harsh conditions of the accelerated aging test, the composition according to Example 1 exhibited no synerersis until the fifth week of the test. At the tenth week of the test, the observed syneresis was minor, being only 8/200 mm.

The accelerated aging test was also performed for Examples 1, 2 and 3 and these samples also exhibited no synerersis until the fifth week of the test.

Surprisingly, in contrast to the results of the accelerated aging test described above, the compositions according to Examples 1, 2 and 3 which were maintained at ambient room temperature (approx. 20"C) did not exhibit any visibly discernible change from their initial appearance, indicating superior syneresis characteristics.

Claims (5)

Claims: 1. Aqueous thickened bleach containing compositions which comprise in parts by weight (based on the total weight of the composition): 0.5 - 5.0 of an alkali metal carboxylate; 0.25 - 6.0 of a water dispersible nonionic amine oxide; 0.5 - 8.0 of a water dispersible anionic surfactant system including one or more sulfate or sulfonate surfactants; 0.5 - 4.0 of an alkali metal salt, preferably an alkali metal chloride; 0.1 - 10.0 of an pH adjusting agent for maintaining the alkalinity of the composition; 0.01 - 10.0 of a bleach releasing material, such as an alkali metal hypochlorite;

1.0 - 50 of an abrasive material, preferably a particulate abrasive material; optionally, 0.05 - 3.0 of an detergency builder, and, water.

2. Aqueous thickened bleach containing compositions according to claim 1 which comprise in parts by weight (based on the total weight of the composition): 0.5 - 5.0 of an alkali metal carboxylate; 0.4 - 6.0 of a water dispersible nonionic amine oxide; 0.5 - 8.0 of a water dispersible anionic surfactant system including one or more sulfate or sulfonate surfactants; 0.5 - 4.0 of an alkali metal salt, preferably an alkali metal chloride; 0.1 - 10.0 of an pH adjusting agent for maintaining the alkalinity of the composition; 0.01 - 10.0 of a bleach releasing material, such as an alkali metal hypochlorite;

1.0 - 50 of an abrasive material, preferably a particulate abrasive material; optionally, 0.05 - 3.0 of an detergency builder, and, water.

3. The compositions according to claim 1 or 2 wherein the alkali metal carboxylate is an alkali metal soap.

4. The compositions according to any preceeding claim wherein the water dispersible anionic surfactant system further includes a diphenyl disulfonate surfactant;

5. The composition according to claim 1 substantially as described with reference to Examples 1 - 4.