CA1337783C - Spray application of bleach compositions - Google Patents

Abstract

Bleach compositions, such as aqueous sodium hypochlorite formulations, are thickened by admixing the composition with a viscoelastic surfactant.
Viscoelastic surfactants comprise surfactant ions and organic counterions that associate in the bleach composition to form the viscoelastic surfactant.
Thickened bleach compositions of this invention exhibit bleach stability, phase stability, and viscosity stability for acceptably long periods of time. The thickened bleach compositions can be employed as nonmisting sprays and streams which will stick to vertical surfaces without substantial dripping and can be applied to various substrates using a dispensing device.

Description

1 3377~3 THICKENED BLEACH COMPOSITIONS AND
METHOD FOR PREPARING THE SAME

The present invention relates to bleach compositions. In particular, it relates to thickened bleach compositions and the method of thickening them.

Bleach compositions are typically aqueous solutions of alkali metal and alkaline earth metal hypochlorites. They are useful as cleaning agents, disinfectants, bactericides and fungicides. For example, bleach compositions are useful for cleaning textiles, dishes and glassware; and sinks, bathtubs and numerous other porcelain items.

Bleach compositions contain mostly water and therefore have viscosities similar to water.
Unfortunately, it is often necessary to apply bleach compositions to vertical or inclined surfaces~ Because the composition has low viscosity, it will not adhere to a vertical or inclined surface. A thickened bleach 33,715B-F -1-1 3377~3 composltion whlch could be easlly applled, for example by spraylng, and could adhere to a vertlcal or incllned surface wlthout drlpping would be desirable. Thickened bleach compositions are disclosed ln U.S. patent Nos. 4,388,204;
4,390,448; EP0 appllcation No. 110,544 and British patent No.
1,466,560. The bleach compositions of the references use varlous detergents or surface-active agents to thicken the composition. However, no one- or two-component surfactant additive system has been proven satlsfactory wlth regard to phase stablllty, bleach stablllty, and vlscoslty stablllty.
Therefore, lt would be deslrable to provlde a thlckened bleach compositlon that employs only a one- or two-component additive system and exhibits good phase stabillty and bleach stabllity, as well as viscosity stabillty.
Bleach composltions are often applied to numerous items using dlspensers like the manually operated atomizing dispensers disclosed in U.S. patent No. 4,463,905.
Unfortunately, when typical bleach compositions are employed as a spray uslng such a dlspenser, they can form an undesirable mist. This mist can cause problems if the vapors are lnhaled, slnce the vapors can be disagreeably strong, as well as in~urious to health. In additlon, the mlst can drlft undeslrably onto unprotected surfaces. For example, lt can come into contact wlth clothing and other fabrics, skin and eyes. Therefore, it would be deslrable to provlde a thlckened bleach composltlon that can be employed as a substantlally nonmlsting spray while still maintaining its stabillty.

1 3377~3 Accordlng to one aspect of the present lnventlon there ls provlded a method of thlckenlng an aqueous bleach composltlon contalning a bleachlng agent, comprlslng the step of contactlng the composltlon with an effectlve amount of a surfactant composltlon of onlum surfactant ions and aromatlc sulfonate counterlons or aromatlc carboxylate counterlons to form an a~ueous solutlon under sultable solutlon condltlons whereby the onlum surfactant lons and aromatlc counterlons assoclate ln the bleach composltion to form a viscoelastic surfactant and measurably increase the viscoslty of the solution.
Accordlng to a further aspect of the present invention there is provided the composition of claim 14 wherein the fluoroallphatic group is linear.
The addition of excess organic counterions to the bleach composition in accordance with the practice ~J' 4 1 3 3 7 7 ~ 3 of this invention can further increase its viscosity, increase its viscosity stability at higher temperatures, or bothO

The thickened bleach compositions of this invention are useful because they exhibit good phase stability, bleach stability, and viscosity stability, and they will adhere to a vertical or inclined surface without dripping. They are also useful because they can be employed as a ~ubstantially non-misting spray.

This invention allows the skilled artisan to produce a thickened bleach composition. It also allows the skilled artisan to apply the composition in the form of a spray to a surface by expelling the composition from a dispensing device. The thickened or gelled bleach composition can be expelled from the dispenser easily despite its thickened character because the composition is thickened with a viscoelastic surfactant that can provide a shear thinning behavior. Because the viscoelastic surfactant is also ~hear ~table, it also allows the bleach composition to thicken after it is expelled from the dispenser; as for example, when the composition is applied to a surface. Therefore, the bleach composition can be applied to a vertical surface without substantial running or dripping. In addition, the bleach composition can be applied in the form of a stream or~spray to a surface without the formation of an undesirable mist as the composition is expelled from a dispenser.

As used herein9 the term "bleach composition"
refers to an aqueous liquid that contains a bleach active agent. Such agents include hydrogen peroxide, 33,715B-F -4-1 3377~3 potassium perchlorate, sodium hypochlorite, sodium peroxide, sodium chlorite, calcium hypochlorite (i.eO, chlorinated lime), sodium hypobromite, and iodine nonionic surfactant complexes. Typically, bleach compositions range from 0.5 to 50, preferably from 1 to 10 weight percent bleaching agent and from 50 to 99.5, preferably from 90 to 99, weight percent aqueous liquidO The concentration of bleaching agent required will depend on the bleaching agent employed.
The term "aqueous liquid" refers to liquids which contain water. Included herein are substantially pure water, water containing inorganic salts, and aqueous alkaline and acidic solutions. Aqueous liquids include mixtures of water and water-miscible liquids, provided that the concentration of water-miscible liquids does not adversely affect the stability of the bleach composition or the viscoelastic properties of the aqueous liquid. Also included herein are emulsions of immiqcible liquids in water, and -~prayable aqueous slurries of ~mall sized solid particulates. Therefore, the aqueous liquids of this invention can contain fine particulate bentonites, silica, and/or calcium carbonate. Water, water containing inorganic salts and aqueous alkaline, and acidic solutions are preferred.
Mo~t preferred is an aqueous alkaline solution wherein the total electrolyte concentration is less than 25, preferably les~ than 10, weight percent of the aqueous 3~ liquid-The aqueous liquid of this invention need notcontain gritty materials, which are undesirable in some applications, to thicken the bleach composition. For 33,715B-F -5-example, gritty materials can be difficult to adequately remove from certain surfaces.

The term "mist" as it applies to aqueous liquids, means ~ine liquid droplets suspended in or falling through a moving or stationary gas atmosphere.
Specifically, a mist provides an undesirable drift of aqueous droplets through a gas atmosphere. The properties of a mist, and tests to determine such properties are well known in the art and reference is made to Perry and Chilton, Chemical En~ineer's Handbook, 5th Ed. 9 Vol. 18, McGraw-Hill (1973). In distingui~hing a mist from a spray, a mist is generally defined as a gas-suspended liquid particle which has a diameter of less than 10 ~m, while a spray is a gas-suspended liquid particle which has a diameter of greater than 10 ~m. However, it is understood that the specific size of spray and mist particles may vary depending upon the industrial use such as where a controlled droplet size-is desired. As used herein, the terms "antimisting" and "non-misting" as applied to an aqueous liquid refers to the property which comprises the tendency of said liquid to not form a mist, i.e., undersized droplets that are easily gas-suspended.
- The terms "dispenser" and "dispensing device"
refer to devices which can provide a stream or spray of the bleach compo~ition as defined herein. Typically, the dispenser is a hand-held device. For example, the dispensing device can include a container for the bleach composition, a pump, and a spray-forming or stream-forming nozzle. The pump ejects the bleach composition from the container, through the nozzle, and into the atmosphere. Examples of suitable dispensing 33,715B-F -6-devices are disclosed in U.S. Patent Nos. 4,463,905;
3,572,590; 3,985,271; 2,826,399; 4,013,228 and 49153,208. The preferred dispensing devices have parts that are resistant to chemical attack by bleach. They also can include a suitable aerosol device that has a propellant, an atomizer, or both. Preferably, the aerosol device is one which forms a spray when employed.

Traditionally, engineers and scientists have been concerned with two separate and distinct classes of materials - the viscous fluid and the elastic solid.
The simple linear engineering models, Newton's law for flow and Hooke's law for elasticity, worked well because most traditional materials (e.g., water, motor oil, and steel) fell in one of these two categories.
However, as polymer science developed, scientists realized that these two categories represented only the 20 extremes of a broad qpectrum of material properties, and that polymers fell somewhere in the middle. As a result, polymer melts and solutions were characterized as "vi~coelastic". The term "viscoelastic" refers to polymers that exhibit a combination of viscous (liquid-25 like) and elastic (solid-like) properties.

The phenomenon of viscoelasticity has been discovered in certain aqueous surfactant solutions.
Surfactants consist of molecules containing both polar and non-polar groups. They have a strong tendency to adsorb at qurfaces or interfaces and thereby lower the sur~ace or interfacial tension. Solutions of surfactants also form micelles, which are organized aggregates of the surfactants. A selected group of 35 surfactant solutions also impart viscoelasticity to the solution as well. (See S. Gravsholt, J. Coll. and 33,715B-F _7_ -8- j 3 3 7 7 ~ 3 Interface Sci., 57 (3) pp. 575-6 (1976), for a study of various surfactant compositions that impart viscoelasticity to aqueous solutions.) However, typical surfactant compositions will not inherently possess viscoelastic properties. As reported in H. Hoffmann, Advances in Coll. and Interface Sc~., 17 pp. 276 (1982), surfactant compositions that impart viscoelastic properties to solutions are rare.
Therefore, although all surfactant compositions will reduce surface tension, few will impart visco-elasticity. Those that do are known as "viscoelastic surfactants", and they possess desirable properties.
It has been discovered that viscoelastic surfactants can be added to a water-based heat transfer fluid to improve its performance (U.S. Patent 4,534,875).

Viscoelasticity is caused by a different type of micelle formation than the usual spherical micelles 20 formed by most surfactant compositions. ~iscoelastic surfactants form rod-like or cylindrical micelles.
Although cylindrical micelles and spherical micelles have about the same diameter of 50 ~ (0.005 ~m), cylindrical micelles can reach 1,000 to 2,000 ~ (0.1 to 25 0. 2 ~m) in length and contain hundreds or thousands of individual surfactant molecules. This high degree of association requires a specific set of conditions that can only be achieved by matching the surfactant composition with a suitable solution environment. The 3 solution environment will depend on factors such as the type and concentration of electrolyte and the structure and concentration of organic compounds present.
Therefore, a surfactant composition may form 35 cylindrical micelles in one solution to impart viscoelastic properties to it and form spherical 33,715B-F - -8--9- 1 3 3 7 7 ~ 3 micelles in another solution. The solution with spherical micelles will exhibit normai surfactant behavior and will not exhibit viscoelasticity. A
determination of whether a olution is viscoelastic can be easily determined by empirical evaluation as described hereinafter.

The formation of long, cylindrical micelles in viscoelastic surfactants creates useful rheological properties. First, viscoelastic surfactants exhibit reversible shear thinning behavior. This means that under conditions of high stress, such as when the composition is sprayed through a nozzle, the composition will exhibit low viscosity. When the ~onditions of high stress are replace~d with conditions of low stress, such as obtained when the composition has left the nozzle and is only subjected to gravitational force as it resides on a vertical urface, the composition will exhibit high viscosity.
Secondly, viscoelastic surfactants will remain stable despite repeated high shear applications. Therefore, the thickened composition can be sprayed efficiently Prom a dispenser without undesirable mist and yet maintain its integrity on a vertical wall without running or dripping. Since typical polymeric thickeners will degrade when subjected to high shear, a bleach composition thickened with such a polymer will lose its integrity after repeated shearing.
The major test specified by the references discussed above to determine if an aqueous solution possesses viscoelastic properties consists of swirling the solution and visually observing whether the air bubbles created by the swirling recoil after the swirling is stopped. This has been the traditional 33,715B-F -9-- l o -test for many years. It is possible to quantify the degree of viscoelasticity a solution possesses by measuring the time required for the recoil motion to stop, as described in an article by J. Nash, 5 J. of Appl. Chem., 6, pp. 540 (1956).

The surfactant compositions within the scope of this invention are ionic viscoelastic surfactants. The proper choice of counterion structure and solution environment gives viscoelasticity. It has been discovered that certain viscoelastic surfactants will thicken a bleach composition without unduly sacrificing bleach stability. What follows is a discussion of ionic surfactant compounds and the counterions ~5 necessary to impart viscoelasticity to bleach composition~.

In general, ionic surfactant compounds comprise an ionic, hydrophilic moiety chemically bonded to a _ 20 hydrophobic moiety (herein called a surfactant ion) and a counterion sufficient to satisfy the charge of the surfactant ion. Examples of such surfactant compounds are represented by the formula:

_ 25 R1(Y~)Xe or R1(Ze)A~

wherein R1 (Yffl) and R1(Ze) represent surfactant ions having a hydrophobic moiety represented by R1 and an ionic, solubilizing moiety represented by the cationic 3 moiety Yffl or the anionic moiety ze chemically bonded thereto. Xe and A~ are the counterions associated with the respective surfactant ions.

In general, the hydrophobic moiety (i.e., R1) - 35 ~of the surfactant ion is a hydrocarbyl or inertly -substituted hydrocarbyl radical having one or more 33,715B-F -10-1l 1 3377~

substituent groups, e.g., halo groups such as -F, -Cl, or -Br or chain linkages, such as silicon linkage (-Si-), which are inert to the aqueous liquid and components contained therein. Typically, the hydrocarbyl radical is an aralkyl group or a long chain alkyl or inertly substituted alkyl, which alkyl groups are generally linear and have at least 12 carbon atoms.
Representative long chain alkyl groups include dodecyl (lauryl), tetradecyl (myristyl), hexadecyl (cetyl), 0 octadecyl (stearyl) and the derivatives of tallow, coco and soya. Preferred groups are generally alkyl groups having from 14 to 24 carbon atoms, with octadecyl, hexadecyl, and tetradecyl being the most preferred.

The cationic, solubilizing hydrophilic moieties or groups, i.e., Y~, are generally onium ions wherein the term "onium ions" refers to a cationic group which is essentially completely ionized in water over a wide range of pH, e.g., pH values of from 2 to 13.
Representative onium ions include, for example, quaternary ammonium groups, i.e., -N~(R)3; tertiary sulfonium groups, i.e., -S~(R)2; and quaternary phosphonium groups, i.e., -P~(R)3, wherein each R is individually a hydrocarbyl or inertly substituted hydrocarbyl. Of such cationic groups, the surfactant ion of the viscoelastic surfactant is preferably prepared having a quaternary ammonium group, i.e., -N~(R)3, with each R preferably being methyl or ethyl.
Representative anionic, solubilizing hydro-philic moieties or groups, herein designated ze, include sulfate groups, ether sulfate groups, sulfonate groups, carboxylate groups, phosphate groups, and phosphonate groups. Of quch anionic groups, the surfactant ion of the viscoelastic surfactants is 33,715B-F -11--12- l 3 3 7 7 ~ 3 preferably prepared having a carboxylate or sulfate group. The most preferred anionic surfactant ion is an alkyl diphenyl ether disulphonate sold by The Dow Chemical Company, under the trademark "DOWFAX 2A1", especially where the alkyl group is octadecyl.

Fluoroaliphatic species suitably employed in the practice of this invention include organic compounds represented by the formula:

RfZl wherein Rf is a saturated fluoroaliphatic moiety, preferably containing a F3C- moiety and z1 is an ionic moiety. The fluoroaliphatics can be perfluorocarbons.
Suitable ionic moieties will be described hereinafter.
The fluoroaliphatic moiety advantageously contains from 3 to 20 carbons wherein all can be fully fluorinated, preferably from 3 to 10 of such carbons. This fluoroaliphatic moiety can be linear, branched or cyclic, preferably linear, and can contain an occasional carbon-bonded hydrogen or halogen other than fluorine. More preferable are those linear perfluoroaliphatic moieties represented by the formula:
CnF2n,1 wherein n is in the range of from 3 to 10. An example of a linear perfluorocarbon that is stable to oxidation is CF3(CF2)pS03eA~, wherein p is from 2 to 6.
The method of its preparation is described in U.S.
Patent 2~732~398.
The counterions (i.e., Xe or A~) are organic ions that have a charge opposite that of the surfactant ions. The counterions and surfactant ions associate in the bleach composition and impart viscoelastic properties to it. Organic ion~ that are anionic serve - 33,715B-F -12--13- l 3 3 7 7 ~ 3 as counterions for surfactant ions having a cationic, hydrophilic moiety; and the organic ions that are cationic serve as counterions for surfactant ions having an anionic, hydrophilic moiety. The organic counterions are formed by dissociation of the corresponding salts, acids, or bases.

The preferred anionic counterions are sulfonates or carboxylates. Representative of such anionic counterions which, when employed with a cationic surfactant ion, are capable of imparting viscoelastic properties to the bleach composition include various aromatic sulfonates such as p-toluene sulfonate and naphthalene sulfonate; and chlorobenzoic acid, ~here such counterions are water-soluble. Most preferred are p-toluene sulfonate, 3, 4-dichlorobenzoate, and an alkyl diphenyl ether disulphonate sold by The Dow Chemical Company, under the trademark "DOWFAX 2A1", especially where the alkyl group is octadecyl.

The cationic counterion may be an onium ion, most preferably a quaternary ammonium group.
Repres~ntative cationic counterions in the form of a quaternary ammonium group include benzyl trimethyl ammonium or alkyl trimethyl ammonium wherein the alkyl group is advantageously octyl, decyl, dodecyl and cetyl. Most preferred is an alkyltrimethylammonium such as hexadecyltrimethylammonium supplied in the form of the bromide (HTAB). It is highly desirable to avoid stoichiometric amounts of surfactant ions and counterions when the alkyl groups of the counterions are large. The use of cationic counterions is 33,715B-F -13-1 3377~3 -generally less preferred than the use of anionic counterions.

The particular surfactant ions and counter-ions are selected so that the combination impartsviscoelastic properties to an aqueous liquid. Of the aforementioned surfactant ions and counterions, those combinations which form such viscoelastic surfactants will vary but are easily determined by the test methods hereinbefore described. Of the surfactant compounds which impart viscoelastic properties to an aqueous liquid, the preferred surfactant compounds include those represented by the formula:

CH3 ~ CH2 ~ N~R Xe R

wherein n is an integer from 13 to 23, preferably an integer from 15 to 21; each R is independently an alkyl group, or alkylaryl, preferably independently methyl, ethyl or benzyl; and Xe is a p-toluene sulfonate.
Especially preferred surfactant ions include cetyltri-methylammonium, myristyltrimethylammonium, and octadecyltrimethylammonium. Combinations of surfactant 3 compounds can also be employed.
The vi~coelastic surfactants are easily prepared by admixing the basic form of the desired cationic ~urfactant ions with a stoichiometric amount of the acidic form of the desired anionic counterions or by admixing the acidic form of the desired anionic 33,715B-F -14--15- 1 3 3 7 i ~ 3 surfactant ions with a stoichiometric amount of the basic form of the desired cationic counterions.
Alternatively, stoichiometric amounts of the salts of the surfactant ions and counterions can be admixed to form the viscoelastic surfactant. See, for example, the procedures described in U.S. Patent 2,541,816.
Once the viscoelastic surfactant is prepared, the thickened bleach composition is prepared by admixing the viscoelastic surfactant with the bleach 10 composition.

The concentration of viscoelastic surfactant required to impart viscoelastic properties to the bleach composition, where the viscoelasticity is measured by the techniques previously described, is that which measurably increases the viscosity of the composition. The type and concentration of viscoelastic surfactant required to increase the viscosity depends on the-composition of the aqueous liquid, temperature, qhear rate to which the bleach composition will be subjected, and the end use contemplated. In general, the requisite concentration of any specific viscoelastic surfactant is determined experimentally. Preferably, the concentration of viscoelastic surfactant ranges from 0.05 to 10 weight percent of the bleach composition. More preferably, the concentration of viscoelastic surfactant ranges from 0.1 to 2 weight percent of the bleach composition.
In a preferred embodiment of this invention, exce~s organic counterions are added to the bleach composition to further increase its viscosity, increase its visco~ity stability at higher temperatures, or both. The counterions employed will have a charge opposite that of the surfactant ions and will dissolve 33,715B-F -15-16 1 3377~3 in the bleach composition. Preferably, the excess organic counterions employed are the same as the counterions employed to associate with the surfactant ions to form the viscoelastic surfactant. However, the excess organic counterions can be different from the counterions which form the viscoelastic surfactant.

The concentration of excess organic counterions required to further increase the viscosity, increase the stability at higher temperatures, or both, will depend on the composition of the aqueous liquid, the surfactant ions and counterions employed, and the desired viscosity. Ordinarily, the concentration of excess counterions which will produce a noticeable effect ranges from 0.1 to 20, and more assuredly and preferably from 0.5 to 5, moles per mole of surfactant ions.

The bleach composition may contain an emulsion of an immiscible liquid,-such as an oil or other organic ingredient, at a concentration ranging from 0.05 to 20-weight percent of the bleach composition.
However, the concentration of immiscible liquid must be lower than that which will adversely affect the ~tability of the bleach composition. Viscoelastic surfactants employed in such emulsions tend to lose their vi-qcoelasticity,- possibly becau~e the oil penetrates the micelles and destrbys the aggregates required for viscoelasticity. Viscoelastic surfactants containing excess organic counterions maintain viscoela-~ticity in an emulsion longer than those without the excess organic counterions. Moreover, fluorinated viscoelastic surfactants maintain viscoelasticity in an emulsion longer at concentrations 33,715B-F -16-17 l 3 3 7 7 8 3 ranging up to 50 weight percent, most preferably up to 10 weight percent of the bleach composition.

The bleach compositions of this invention exhibit good bleach stability, phase stability, and viscosity stability. Good bleach stability refers to a thickened bleach composition that experiences less than 10 percent bleach degradation, which is the loss of the bleach active agent, for more than 30 days when stored under atmospheric conditions in a clear container in the dark at 30C. Good viscosity stability refers to a bleach composition that exhibits a viscosity at room temperature greater than 600 cps (0.6 Pa-s) when subjected to a shear rate less than 5 sec~1, more than 30 days after the composition is formulated and stored using the test conditions above. Good phase stability refers to the lack of development of separate phases for the bleach composition and viscoelastic surfactant until the bleach activity falls below useful values (for example, 75 percent bleach degradation).

If desired, the bleach composition can be a foam, which is a thickened liquid having a dispersion of gas therein. For example, the bleach composition can be vigorously agitated prior to use as a spray or stream. In addition, a surfactant, or other foam forming material can be used aq an additive.
Furthermore, a fine mesh screen device can be fitted over the nozzle of the dispensing device to intercept emitted bleach composition.

The following examples are presented to further illustrate but not limit the scope of thi~ invention.
All parts and percentages are by weight unless otherwise indicated.

33,715B-F -17--18- 1337~3 Example I and Comparative Run A

To 71.43 grams (g) of a commercially available NaOCl bleach formulation, sold by Gibraltar National Corporation under the trademark "ROMAN BLEACH", which contained an aqueous liquid and 5.6 percent active NaOCl was added 27.45 g distilled water. To this solution was added 0.73 g hexadecyltrimethylammonium bromide and 0.39 g sodium p-toluene sulfonate. The mixture was agitated to the point at which a uniform viscoelastic solution resulted.

The sample was transferred to a polyethylene bottle which was sealed and placed in a constant temperature (31C) dark environment. Portions of the sample were periodically removed in order to evaluate the NaOCl concentration. The amount of NaOCl was determined using titration techniques employing sodium thiosulfate and starch/iodine indicator. Viscosity of the thickened bleach compositions were periodically evaluated using a Rheometrics Fluids Rheometer in a steady shear mode, and cone and plate configuration.
Data are presented in Table I.

33,715B-F -18-w ~I
1~ TABLE I
~n Viscositv of ComPosition, cp (Pa-s) after:
4 hours 24hours 35days Example 8 Percent of Original Comparative NaOCI remaining after: Shear Rate (sec-l) Shear Rate (sec~l) ~Shear Rate (sec~l) Run 19Davs 26Days40Davs 15.85 2.51 0.6311585 2.51 0631 15.85 251 0.631 93.8 93.5 92.3 167 398 633 418 1076 2360 345 883 1879 (0.167)(0.398j (0.633) 10.418) (1.076) (2.36)(0.345) (0.883) (1.879) A 96.5 95.8 94.3 N.M. N.M. N.M.N.M. N.M. N.M. N.M. N.M. N.M.
~o I

N.M. indicates that the viscosity of the composition is not measured, but the viscosity of the sample approximately equals that of an unthickened aqueous liquid (i.e., about 1 cp). ~ ,~

-20- 1 33 7 7 ~ 3 The data in Table I illustrate that the thickened formulation of this invention is shear thinning and exhibits excellent bleach stability over time as well as acceptable high viscosity stability.
Conversely, a similar bleach composition thickened with 1 percent sodium polyacrylate rather than a - viscoelastic surfactant (Comparative Run A) experienced 84 percent reduction in viscosity after 18 days of similar treatment conditions. This is an unacceptably high rate of loss of thickening activity.

Example 2 To 178.57 g of a commercially available NaOCl bleach formulation, sold by Gibraltar National Corporation under the Trademark "ROMAN BLEACH", which contained an aqueous liquid and 5.6 percent active NaOCl was added 166.45 g deionized water. To this solution was added 2.50 g hexadecyltrimethylammonium bromide and 2.50 g sodium p-toluene sulfonate.

The sample was transferred into a dispensing device which is generally described in U.S. Patent No. 4,463,905. The screen in front of the nozzle was removed. A portion of the sample was sprayed onto a greasy vertical enamel painted surface and was observed to provide a good distribution of spray which uniformly covered the surface. The treated surface was cleaned by the sprayed bleach sample. The sample which was sprayed onto the vertical metallic surface was observed to adhere to said surface for several minutes (i.e., 10 minutes) without a substantial amount of dripping occurring. The ~creen in front of the nozzle was reattached to the dispensing device. A portion of the sample was sprayed onto the vertical glass surface as 33,715B-F -20---21- 1 3 3 7 7 8 ~

described hereinbefore. The sample ~hich was sprayed onto the vertical glass surface formed a white, non-transparent, fairly thick foam; which foam adhered to the-surface for several minutes (i.e., 10 minutes) without the occurrence of substantial amounts of dripping. The sample in all three instances was applied as a spray wherein the dispensing device was operated without greater effort than was required for the spraying of essentially pure water. The bleach composition which was sprayed on the aforementioned surfaces was rinsed from the surface using water and no visible film remained on the surfaces.

Example 3 A thickened bleach composition was prepared using the formulation and procedure of Example 1, except that sodium 3,4-dichlorobenzoate was substituted in an equimolar amount for sodium p-toluene sulfonate.
The sample was transferred to a polyethylene bottle which was sealed and placed in a constant temperature (31C) dark environment. Samples of the composition were periodically evaluated using the techniques of Example 1. Data are presented in Table II.
TABLE II
Viscosity of Composition, cp Percent of Original NaOCl (Pa-s), when subjected to Shear Remainin~ After: Rate of 0.631 sec~1 After:

7 days 35 days 70 days 24 hrs. 7 days 35 days 100 87.8 62.3 3020(3.02) 2780(2.78) 1000(1.00) 3 The data in Table II illustrate that carboxylate counterions can replace sulphonate 33,715B-F -21--22- 1 3 3 7 7 ~ 3 counterions to form a viscoelastic surfactant. The bleach composition thickened with the viscoelastic surfactant exhibited excellent bleach stability and viscosity stability over time.

3o 33,715B-F -22-

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. A method of thickening an aqueous bleach composition containing a bleaching agent, comprising the step of contacting the composition with an effective amount of a surfactant composition of onium surfactant ions and aromatic sulfonate counterions or aromatic carboxylate counterions to form an aqueous solution under suitable solution conditions whereby the onium surfactant ions and aromatic counterions associate in the bleach composition to form a viscoelastic surfactant and measurably increase the viscosity of the solution.

2. The method of Claim 1 further comprising the step of adding excess aromatic counterions at a concentration of from about 0.1 to about 20 moles per mole of surfactant ions.

3. The method of Claim 1 wherein said surfactant ion is represented by the formula:

R1(Y?)X? or R1(Z?)A?
wherein R1 is a hydrophobic moiety, Y? is a cationic solubilizing hydrophilic moiety chemically bonded to R1, Z? is an anionic solubilizing hydrophilic moiety chemically bonded to R1, X? is a counterion associated with Y? and A? is a counterion associated with Z?.

4. The method of Claim 3 wherein said cationic solubilizing hydrophilic moiety is selected from quaternary ammonium groups and quaternary phosphonium groups and said anionic solubilizing hydrophilic moiety is selected from sulfate groups, ether sulfate groups, sulfonate groups, carboxylate groups, phosphate groups and phosphonate groups.

5. The method of Claim 4 wherein said anionic solubilizing hydrophilic groups are selected from carboxylate groups and sulfate groups.

6. The method of Claim 1, 2, or 3 wherein said surfactant ion is selected from cetyltrimethylammonium, myristyltrimethylammonium and stearyltrimethylammonium.

7. The method of Claim 1 wherein the thickened composition produced is substantially nonmisting when sprayed.

8. The method of Claim 1 wherein the viscoelastic surfactant ranges from 0.05 to 10 weight percent of the bleach composition.

9. The method of Claim 8 wherein the viscoelastic surfactant formed is from 0.1 to 2 weight percent of the bleach composition.

10. The method of Claim l wherein the bleach composition comprises from 0.5 to 50 weight percent bleaching agent and from 50 to 99.5 weight percent aqueous liquid based on the weight of the bleach composition.

11. A bleach composition thickened with from about 0.05 to about 10 weight percent of a surfactant composition comprising onium surfactant ions and aromatic sulfonate counterions or aromatic carboxylate counterions formed into an aqueous solution under suitable solution conditions whereby the onium surfactant ions and aromatic counterions associate in the bleach composition to form a viscoelastic surfactant.

12. The composition of Claim 11 further comprising excess aromatic counterions at a concentration of from about 0.1 to about 20 moles per mole of surfactant ions.

13. The composition of Claim 11 wherein the onium surfactant ions comprise a hydrophilic moiety selected from the group consisting of quaternary ammonium groups and quaternary phosphonium groups.

14. The composition of Claim 11 wherein the onium surfactant ions comprise a hydrophobic moiety containing a fluoroaliphatic group.

15. The composition of Claim 14 wherein the fluoroaliphatic group is linear.

16. The composition of Claim 15 wherein the fluoroaliphatic group is a perfluorocarbon.