GB2280682A - Effective control of ammonia odor in hexangonal phase detergent gels containing urea - Google Patents

Abstract

A detergent composition comprising a gel wholly or predominantly in hexagonal liquid crystal phase, said gel comprising: (a) from 15% to 70% anionic surfactants selected from alkylbenzene sulfonates, alkyltoluene sulfonates, paraffin sulfonates, olefin sulfonates, alkyl sulfates, ethoxylated alkyl sulfates, alpha-sulfonated fatty acid alkyl esters, alkyl glyceryl ether sulfonates, dialkyl sulfosuccinates, coconut oil fatty acid monoglyceride sulfates and sulfonates, alkylphenolpolyethylene oxide ether sulfates, beta-acetoxy- and beta-acetamido-alkanesulfonates, and mixtures thereof; (b) from 0% to 30% optional co-surfactants; (c) from 10% to 35% urea; (d) from 20% to 70% water; (e) a strong acid selected from the group consisting of acid precursors of hydrotropes, acid precursors of anionic surfactants (a), and mixtures thereof; and (f) a weak acid; wherein the pH of the detergent gel is between 7.0 and 7.5, and wherein the total amount of surfactants (a) + (b) in the detergent gel is from 15% to 70% by weight of the gel. The detergent gel composition provides effective control of ammonia odor without requiring the addition of boric acid.

Description

EFFECTIVE CONTROL OF AMMONIA ODOR IN HEXAGONAL PHASE DETERGENT GELS CONTAINING UREA FIELD OF THE INVENTION This invention relates to detergent gel compositions containing urea, in particular hexagonal phase dishcare detergent gels. The invention provides effective control of ammonia odor in such gels.

Detergents in gel form present many advantages. For example, dishcare gels are preferred for use in washing dishes in some parts of the world. The gel product form best lends itself to the "direct application" habit in which persons apply a wet sponge or other cleaning applicator directly onto the dishcare detergent and then onto the dishes; the dishes are then typically washed and rinsed under running water. Additionally, gels can be stored in inexpensive tubs instead of the more complex plastic bottles required for liquid cleaners.

Hexagonal phase detergent gels of the prior art are often made by combining urea with a secondary anionic or cationic surfactant, where the urea functions to force the surfactant into hexagonal phase. Unfortunately, urea degrades to ammonia over time, causing a strong odor which can be objectionable to consumers.

One way to address the ammonia odor problem has been by the addition of boric acid to the detergent gels. While not intending to be limited by theory, it is believed that boric acid works by complexing the ammonia, thereby forming an amine borane. However, this chemical reaction takes place at equilibrium conditions in basic media, such as detergent gels, so that there is still some ammonia present even after boric acid addition. Perfumes are often added to the detergent gels in an attempt to cover up the remaining ammonia odor, but this method is not totally effective.

Therefore, it is an object of the present invention to provide urea-containing hexagonal phase detergent gels in which ammonia odor is effectively controlled.

It is another object of the present invention to provide effective control of ammonia odor in such gels by a method which does not require the addition of boric acid.

It is a further object of the present invention to provide detergent gels which have good viscosity.

These and other objects of the present invention will be described in more detail hereinbelow.

SUMMARY OF THE INVENTION The invention is a detergent composition comprising a gel wholly or predominantly in hexagonal liquid crystal phase, said gel comprising: (a) from about 154: to about 70%, by weight of the detergent gel, anionic surfactants selected from the group consisting of al kyl benzene sulfonates, alkyltoluene sul fonates, paraffin sulfonates, olefin sulfonates, alkyl sulfates, ethoxylated alkyl sulfates, alpha-sulfonated fatty acid alkyl esters, alkyl glyceryl ether sulfonates, dialkyl sulfosuccinates, coconut oil fatty acid monoglyceride sulfates and sulfonates, al kyl phenol pol yethyl ene oxide ether sulfates, beta-acetoxy- and beta-acetamido-alkanesulfonates, and mixtures thereof;; (b) from OYO to about 30% optional co-surfactants by weight of the detergent gel; (c) from about 10% to about 35Z urea by weight of the detergent gel; (d) from about 20% to about 70% water by weight of the detergent gel; (e) a strong acid selected from the group consisting of acid precursors of hydrotropes, acid precursors of anionic surfactants (a), and mixtures thereof; and (f) a weak acid; wherein the pH of the detergent gel is between about 7.0 and about 7.5, and wherein the total amount of surfactants (a)+(b) in the detergent gel is from about 15% to about 70% by weight of the gel.

The detergent gel composition provides effective control of ammonia odor without requiring the addition of boric acid. The detergent gel also has good viscosity.

DETAILED DESCRIPTION OF THE INVENTION A. Addition of Strona Acid and Weak Acid This invention provides a method for control of ammonia odor in hexagonal phase detergent gels containing urea. The invention is more effective for control of ammonia odor than adding boric acid, and it does not result in a significant weakening of gel structure (viscosity). At a pH of about 7.4 and below, ammonia is not readily detectable by the human nose. The present invention takes advantage of this fact by providing detergent gel compositions containing a strong acid and a weak acid to lower pH and thereby eliminate ammonia odor. The strong acid provides a significant pH lowering, but it does not have a buffering capacity.Therefore, the weak acid is added to act as a buffer to stabilize the pH so that the pH does not drift back up as a result of urea degradation. (The weak acid also lowers the pH a small amount.) Conventional detergent gels typically have a basic pH between about 8 and about 10 because of the composition of their raw materials (e.g., residual amounts of base in the surfactant raw material).

According to the present invention, the pH of the detergent gels is lowered to between about 7.0 and about 7.5, preferably between about 7.0 and about 7.4. The pH of the gels must be kept above about 7.0 in order to obtain a good hexagonal phase gel of sufficient viscosity. Reducing the pH tends to reduce the viscosity and overall structure of the gel.

The strong acid is selected from the group consisting of acid precursors of the anionic surfactants (a) used in the detergent compositions, acid precursors of hydrotropes, and mixtures thereof.

Using these strong acids diminishes the negative impact on gel strength of reducing the pH, since the neutralized surfactants and hydrotropes are themselves gel forming agents. Preferred acid precursors of surfactants include alkylbenzene sulfonic acid, alkyl sulfuric acid, ethoxylated alkyl sulfuric acid, and ixtures thereof. Acid precursors of hydrotropes which are useful as strong acids include cumene sulfonic acid, xylene sulfonic acid, toluene sulfonic acid, 2-ethyl-hexyl sulfonic acid, and mixtures thereof.

Inorganic strong acids and polymeric strong acids are not acceptable for use as strong acids in the invention because they adversely impact gel viscosity.

The weak acids added to the detergent compositions act as buffers to stabilize the pH, preventing urea decomposition from steadily increasing pH over time. Preferred weak acids for use in the compositions include citric acid, malic acid, maleic acid, succinic acid, formic acid, and mixtures thereof, most preferably citric acid. The weak acids preferably have a pKa between about 1.5 and about 5.0. Weak acids which would not work in the invention include weak polymeric acids, because such acids significantly decrease gel viscosity. Fatty acids are not preferred but may be used in amounts less than 0.5% by weight of the gel.

The combination of the strong acid and the weak acid lowers the pH of the detergent gel composition to between about 7.0 and about 7.5.

Preferably the detergent gel contains from about 0.2 to about 2.0% strong acid and from about 0.17. to about 1.59: weak acid, by weight of the detergent gel, more preferably from about 0.2% to about 1.0% strong acid and from about 0.1% to about 1.0% weak acid.

B. Urea The detergent gel contains from about 10% to about 35% urea by weight of the gel. Typically the gels contain from about 159: to about 30X urea by weight. Urea is used because it is capable of forcing the surfactants into hexagonal phase, but it also decomposes and degrades to ammonia over time in the gels. The gels may optionally contain up to 5% by weight short chain urea homologs and analogs, including methyl urea, ethyl urea, thiourea, formamide, acetamide, and mixtures thereof, but the gels of this invention must also contain at least about 10% urea by weight.

C. Anionic Surfactants and ODtional Co-surfactants The present detergent gel composition contains from about 15% to about 70%, by weight of the detergent gel, anionic surfactants selected from the group consisting of alkylbenzene sulfonates, alkyltoluene sulfonates, paraffin sulfonates, olefin sulfonates, alkyl sulfates, ethoxylated alkyl sulfates, alpha-sulfonated fatty acid alkyl esters, alkyl glyceryl ether sulfonates, dialkyl sulfosuccinates, and mixtures thereof.

Suitable alkylbenzene or alkyltoluene sulfonates include the alkali metal (lithium, sodium, and/or potassium), alkaline earth (preferably magnesium), ammonium and/or alkanolammonium salts of straight or branched chain alkylbenzene or alkyltoluene sulfonic acids in which the alkyl group contains from about 9 to about 15 carbon atoms. Preferred alkylbenzene sulfonates are those in which the alkyl chain is linear and averages about 11 to about 13 carbon atoms in length, most preferably from about 11.3 to about 12.3 carbon atoms in length. Examples of commercially available alkylbenzene sulfonates useful in the present invention include Conoco SA 515 and SA 597 marketed by the Continental Oil Company and Cay soft LAS 99 marketed by the Pilot Chemical Company.

Suitable paraffin sulfonates are those having 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms, in the alkyl moiety. A suitable commercially available paraffin sulfonate useful in the present invention is Hostapur SAS 60 marketed by the Hoechst Celanese Corp.

Suitable olefin sulfonates of this invention are compounds produced by the sulfonation of alpha-olefin by means of uncomplexed sulfur trioxide followed by neutralization of the acid reaction mixture under conditions such that sultones formed in the reaction are hydrolyzed to give corresponding hydroxyalkanesulfonates. The alpha-olefins from which the olefin sulfonates are derived are mono-olefins having from about 12 to about 24 carbon atoms, preferably from about 14 to about 16 carbon atoms. Preferably, they are straight chain olefins. Examples of suitable 1-olefins include 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and 1-tetracosene.

The alkyl sulfates useful herein are those obtained by sulfating an alcohol having from about 8 to about 22 carbon atoms, preferably from about 12 to about 16 carbon atoms. The alkyl sulfates have the formula [ROS03-]jM+l where R is the Cog 22 alkyl group, M is a counter-ion such as sodium, potassium, ammonium, alkanolammonium and magnesium, and i is either 1 or 2 depending on whether the counter-ion is mono- or divalent. Specific examples of suitable alkyl sulfates include lauryl sulfates, stearyl sulfates, palmityl sulfates, decyl sulfates, myristyl sulfates, tallow alkyl sulfates, coconut alkyl sulfates, C12-15 alkyl sulfates and mixtures of these surfactants (with the above-mentioned counter-ions).

The suitable ethoxylated alkyl sulfate surfactants are derived from ethoxylating an alcohol having from about 8 to about 22 carbon atoms, preferably from about 12 to about 16 carbon atoms, with from about 1 to about 30 moles of ethylene oxide, preferably from about 1 to about 12 moles of ethylene oxide and then sulfating. The ethoxylated alkyl sulfates have the formula tRO(C2H4O)XSO3-]jM+i where R is the Cog 22 alkyl group, x is 1-30, M is a counter-ion such as sodium, potassium, ammonium, alkanolammonium and magnesium, and i is either 1 or 2 depending on whether the counter-ion is mono- or divalent.

Preferred ethoxylated alkyl sulfate surfactants according to the present invention include those where the alkyl group is derived from coconut or palm base, such as mid-cut coconut (C12.14) or broad-cut coconut (C1218). Surfactants of this type are available commercially from Akzo Chemicals, 516 Duren, Germany, under the tradenames ELFAN NS 243 S conc. and NS 242 S conc. (Na+ cation, alkyl group having an average chain length of C12-14 average degree of ethoxylation of 3 and 2 respectively), and ELFAN NS 243 Mg conc. (same as above, but with Mg++ cation). Preferred ethoxylated alkyl sulfates of this type are also available commercially from Hoechst Corp.Venezuela, and Taiwan NJC Corp., No. 45, Chung-Cheng Rd., Ming-Hsiung Industrial Park, Ming Hsuing, Chia-Yi Hsien, Taiwan, R.0.C. (Na AE2S and Na AE3S, where the alkyl group is C1214). Synthetic surfactants (derived from synthetic alcohols) such as those containing C12-13 or C12-15 alkyl groups are also preferred. Such synthetic surfactants are commercially available from South Pearl Corp., Puerto Rico, U.S.A. and other companies.

Specific examples of preferred surfactants are Na C12-14AE2S, Na C12-15AE3S, Na C12-13AE1S, and their counterparts containing magnesium cations and/or having other degrees of ethoxylation.

Other suitable surfactants include, but are not limited to, ethoxylated alkyl sulfates surfactants where the alkyl group is lauryl (C12) or myristyl (C14).

The alpha-sulfonated fatty acid alkyl ester surfactant has the general formula:

wherein R1 is straight or branched alkyl having from about 8 to about 20 carbon atoms; R2 is straight or branched alkyl having from about 1 to about 6 carbon atoms; M represents a counter-ion such as sodium, potassium, magnesium, ammonium and alkanolammonium, and i is either 1 or 2 depending on whether the counter-ion is mono- or divalent.

Preferred is an ester salt wherein R1 is C10-16 alkyl, R2 is methyl, and M is Na or K.

Suitable alkyl glyceryl ether sulfonates are those having from about 8 to about 22 carbon atoms, preferably from about 12 to about 16 carbon atoms in the alkyl moiety.

Dialkyl sulfosuccinates useful in the present invention have the formula:

where each of R1 and R2, which may be the same or different, represents a straight chain or branched chain alkyl group having from about 4 to about 10 carbon atoms and preferably from about 6 to about 8 carbon atoms, M represents a counter-ion such as sodium, potassium, ammonium, alkanolammonium and magnesium, and i is either 1 or 2 depending on whether the counter-ion is mono- or divalent.

Other suitable anionic surfactants for use in the present invention are coconut oil fatty acid monoglyceride sulfates and sulfonates; alkylphenolpolyethylene oxide ether sulfates with from about 1 to about 10 units of ethylene oxide per molecule on the average in which the alkyl radicals contain from about 8 to about 12 carbon atoms; and beta-acetoxy- or beta-acetamido-alkanesulfonates where the alkane has from about 8 to about 22 carbon atoms.

The present detergent gel composition can also contain from 0% to about 30% optional co-surfactants by weight of the detergent gel, preferably from 0% to about 20Z by weight. Preferred optional co-surfactants are nonionic surfactants since they can improve mildness to the skin and cleaning performance of the detergent gels.

Nonionic surfactants can include the fatty acyl ethanolamides, ethoxylated fatty alcohols, alkyl phenols, polypropylene oxides, polyethylene oxides, copolymers of polypropylene oxide and polyethylene oxide, sorbitan esters, and the like. Preferred nonionic surfactants are water-soluble amine oxides of the formula:

where R1 is an alkyl moiety of from about 10 to about 18 carbon atoms, and R2 is selected from alkyl groups containing from about 1 to about 3 carbon atoms and hydroxyalkyl groups containing from about 1 to about 3 carbon atoms.

Other surfactants known to those skilled in the art can also be used as optional co-surfactants in the present invention. The other surfactants can be anionic, cationic, zwitterionic, ampholitic or amphoteric. Betaines are preferred amphoteric surfactants, for example alkyl betaines, or amido betaines such as coco amido propyl betaine.

The total amount of surfactants in the detergent gel (the total of the above-described anionic surfactants and any optional co-surfactants) should be from about 15% to about 70% by weight of the gel, preferably from about 20% to about 60, and most preferably from about 25rye to about 50%. At least about 15% total surfactant is needed to make a suitably thickened gel. Above about 70% total surfactant, processing becomes more difficult and the mixture may not exist in the hexagonal phase.

D. Water and Other Ingredients A detergent gel composition according to the invention also contains from about 20% to about 70% water by weight of the gel, preferably from about 25% to about 55you and most preferably from about 30% to about 50%. Higher viscosity gels are made by increasing the amounts of surfactant, urea and other ingredients in the compositions in comparison with the amount of water.

Hydrotropes can be added to the present detergent gel compositions, in amounts between about 1% and about 5% by weight, if needed or desired to increase the viscosity of the gels. Preferred hydrotropes include the alkali metal, preferably sodium, salts of toluene sulfonate, xylene sulfonate, cumene sulfonate, and sul fosucci nate.

The amount of short chain alcohols and glycols (C6 alcohols or lower, e.g., ethyl alcohol, propyl alcohol, ethylene glycol, glycerin) used in the detergent gel compositions should be limited because such alcohols and glycols tend to interfere with formation of a gel structure. It is preferred to limit the amount of short chain alcohols and glycols to not more than about 15% by weight of the gel, more preferably not more than about 10% by weight, and most preferably not more than about 64: by weight. Small amounts of alcohol or glycol within these limits can be used as a processing aid in the formation of gels, and to adjust the viscosity and phase properties of the final product.

High levels of electrolytes adversely affect gel viscosity, and can cause the resulting composition to be a liquid instead of a gel.

Accordingly, the level of electrolytes should be kept below about 10Z by weight of the present detergent gels, preferably below about 8% by weight, and most preferably below about 6X by weight.

"Electrolytes" are more fully described in U.S. Patent 4,615,819 to Leng et al. (assigned to Lever Brothers Co.), issued October 7, 1986, at column 6, line 57 to column 7, line 25 (this patent being incorporated by reference herein).

The detergent gels can contain up to about 205 by weight detergent builder, particularly when the detergent compositions are used as laundry detergents, for example, water-soluble alkali metal salts of phosphates, pyrophosphates, orthophosphates, tripolyphosphates and higher polyphosphates, phosphonates, silicates, citrates, tartrates, and mixtures thereof. In general, however, detergency builders have limited value in dishwashing detergent compositions and use at levels above about 10% in such compositions can restrict formulation flexibility.

The detergent gel compositions of the invention can contain, if desired, any of the usual adjuvants, diluents and additives known to those skilled in the art for use in detergents, for example, bleaching agents, perfumes, amino acids, dyes, anti tarnishing agents, antimicrobial agents, suds enhancers, and the like, without detracting from the advantageous properties of the compositions.

Preferred detergent gels contain abrasives or opacifiers such as silica or titanium dioxide.

E. Gel Viscositv and Phase The detergent compositions of the present invention are in the form of gels which have a viscosity between about 500,000 centipoise and about 6,000,000 centipoise. Gels having viscosities in the lower part of this range are suitable for detergent compositions which require soft gels. Firmer gels are preferred for use as dishcare detergents, particularly dishcare gels intended for use in the "direct application" habit described hereinabove. It is preferred that the viscosity of dishcare gels according to the invention is between about 1,000,000 centipoise and about 5,000,000 centipoise, and more preferably between about 1,500,000 centipoise and about 4,500,000 centipoise.

Viscosity measurements of the gels of this invention are taken by means of an Exact Viscometer HAAKE RV20 ROTOVISCO using a cone and plate geometry with Cone PKl; 1, My30.2. The viscosity is measured on. a 0.5 gram sample of the gel sandwiched between the cone and the instrument's plate, using a shear rate gradient of O to 3 seconds 1, at a temperature of 230C (73.4F). The recorded viscosity corresponds to the highest viscosity reading obtained on the instrument when a sweep time of two minutes is used. Each sample is measured seven times in this manner and the measurements averaged.

A detergent gel according to this invention is wholly or predominantly in hexagonal liquid crystal phase. By "predominantly" is meant greater than about 50%. The liquid crystal phase of the detergent gel can be determined by polarizing light microscope studies, use of X-ray diffraction or other microscopic techniques known to persons skilled in the art. The hexagonal liquid crystal phase is intermediate in rigidity between the lamellar and cubic liquid crystal phases. The hexagonal liquid crystal phase is further described in U.S. Patent 4,615,819 to Leng et al. at column 3, lines 12-31.

F. Uses and Process The detergent compositions of this invention can be dishwashing detergents for use with the "direct application" habit discussed above, or for use with batch dishwashing typical of liquid detergents; general purpose household cleaners for use in cleaning hard surfaces such as metal, glass, ceramic, tile and linoleum; concentrated laundry detergents and/or stain removers including gel laundry detergents and laundry bars made from hard gels; toilet bars; hand cleaners; shampoos; or other detergent compositions known in the detergent field. Laundry detergents according to the invention will contain a large amount of surfactant, builder, and typically components such as brighteners, bleach, enzymes, chelating agents, and suds suppressors.General purpose household hard surface cleaners according to the invention will contain surfactants and builder, in generally similar amounts, sometimes an abrasive, and also preferably a non-aqueous polar solvent such as methanol, ethanol, propanol, ethylene glycol, propylene glycol and glycerin, with the amount of such solvent limited to not more than about 15% by weight to avoid interference with the gel viscosity.

Most preferred detergents according to this invention are dishcare gels suitable for use with the direct application habit, in removing food soils from housewares including dishes, pots and pans, glasses, utensils, etc. The dishcare gels of the invention have very good cleaning ability, particularly cleaning grease/oil and related soils, as indicated by interfacial tension and grease emulsification measurements, and the gels have desired foaming properties.

Moreover, the gels have a smooth, homogeneous consistency, good viscosity, and an attractive transparent or translucent appearance.

The detergent compositions of the invention can be prepared in any suitable manner, for instance by simply mixing together the components. It is preferable to mix the components at elevated temperature, and with continual stirring to ensure complete dissolution of the components. It is also preferable to avoid overheating the composition during processing; preferably the temperature of the composition during processing is kept below about 190F (88-C). Moreover, the gels may be processed at low temperatures of about 90-120F (32.2-40.9'C) and packed cold. The order of mixing is not critical.

The following examples illustrate the effectiveness of boric acid substitutes in controlling ammonia odor. In Example 1, ammonia odor is generated by decomposition of urea as well as the fact that the surfactant of choice is neutralized with ammonia.

ExamPle 1.

Examole Ia.

AExS paste composition: 29.6X NH4AE6.5S, 38.4% NH4AE1S, 11.757.

Ethanol.

Composition: 20.58% AExS paste, 8.00% Mg(LAS)2, 3.42% amine oxide, 0.30% Mg++ as Mg2(citrate)3, 20.00"to urea, 1.00% boric acid.

To 20.20 grams of water containing 0.20 grams of a 1X solution of FD & blue dye #1 and 0.20 grams of perfume (lOOYo active), 10.62 grams of C10-16 amine oxide (32% active, made by P & USA), 0.72 grams of magnesium hydroxide (100% active) and 1.59 grams of citric acid (99.59: active) are added. The mixture is stirred at about 80F (26.7C) using a LABMASTER 1500 MSV 1500 U mixer until all of the solids are dissolved. The temperature of the system is then raised to 180F (82.2'C), 1.01 grams of boric acid and 20.2 grams of urea (99X active) are added. After the solution becomes homogeneous, 16.00 grams of Mg(C11.8LAS)2 (50% active, made by Hoechst Venezuela) and 30.26 grams of AExS paste are added.The temperature of the system is maintained at 180'F (82.2'C) The final product is a blue homogeneous translucent liquid which gels upon cooling. pH of a 6% aqueous solution of gel = 8.5.

ExamDle Ib. Composition: same as la. except that the 1.00 grams of boric acid are replaced with 0.53 grams of cumene sulfonic acid (95% active, made by Ruetgers-Nease). The procedure described for example la. is followed, and the amount of water added is adjusted so as to maintain mass balance.

Examole ic. Composition: same as la. except that the 1.00 grams of boric acid are replaced with 0.53 grams of cumene sulfonic acid, 0.3 grams of citric acid and 3.0 grams of sodium cumene sulfonate. The procedure described for example la. is followed, and the amount of free water added is adjusted so as to maintain mass balance.

Examole ld. Composition: same as la. except that 1.0 grams of boric acid are replaced with 0.53 grams of cumene sulfonic acid, 0.3 grams of coconut fatty acid and 3.0 grams of sodium cumene sulfonate. The procedure described for example la is followed, and the amount of free water added is adjusted so as to maintain mass balance.

Exam lie la. I Example lb.l Example ic. exam lie ld

DH at eouilibrium2 8.0 1 ~ ~- 7.9 7.4 7.5 IFT 0.69 0.70 0.74 0.75 Ammonia odor 7.0 8.0 1.0 2.0 ratin ** Control Gel viscosity 0.6 1.6 1.3 1.0 (Million Centi oise * Gels are allowed to remain at 25*C for a minimum of 45 days and pH is measured using a 64: product concentration.

** Average grades from four expert odor graders, using a 1-10 scale, where 10=very strong ammonia odor, 8=very significant ammonia odor, 6-significant ammonia odor, 4=slight ammonia odor, 2=very slight ammonia odor, and 0=no ammonia odor.

Example 2. Composition: 19.307. Mg(LAS)2, 16.204: NaLAS, 1.00% NaAE3S, 20.00X urea, 2.00% boric acid.

To 4.31 grams of water, 0.02 grams of a 1% solution of FD & blue dye #1 and 0.50 grams of a 1% solution of FD & green dye #8 are added at 77'F (25.0 C) with stirring. The temperature of the mixture is then increased to 170-F (76.7C) and 38.60 grams of Mg(C11.8LAS)2 (507.

active linear alkylbenzene sulfonate made by Hoechst Venezuela), 32.40 grams of NaC11.8LAS (509: active, made by Hoechst Venezuela), 1.45 grams of NaC12-13AE3S (69Z active, made by Hoechst Venezuela) are added sequentially. 2.02 grams of boric acid (99% active) and 20.20 grams of urea (99Y. active) are then added, and stirring is continued at 1700F (76.70C) for two hours. Once a completely homogeneous liquid is obtained, 0.50 grams of perfume are added and the mixture allowed to cool at room temperature. The final product is a gel which upon storage displays an ammonia odor.

A procedure similar to the one noted above is followed except that the boric acid is replaced with 1.38 grams of HC11.8LAS (96% active, made by Hoechst Venezuela) and 0.70 grams of citric acid. The final pH of the product is 7.4, the gel has good viscosity and has no discernible ammonia odor.

Claims (8)

1. A detergent composition comprising a gel wholly or predominantly in hexagonal liquid crystal phase, said gel comprising: (a) from 15% to 70%, by weight of the detergent gel, anionic surfactants selected from the group consisting of alkylbenzene sulfonates, alkyltoluene sulfonates, paraffin sulfonates, olefin sulfonates, alkyl sulfates, ethoxylated alkyl sulfates, alpha sulfonated fatty acid alkyl esters, alkyl glyceryl ether sulfonates, dialkyl sulfosuccinates, coconut oil fatty acid monoglyceride sulfates and sulfonates, alkylphenolpolyethylene oxide ether sulfates, beta-acetoxy- and beta-acetamido alkanesulfonates, and mixtures thereof; (b) from 0% to 30% optional co-surfactants by weight ofthe detergent gel; (c) from 10% to 35% urea by weight ofthe detergent gel;; (d) from 20% to 70% water by weight ofthe detergent gel; (e) a strong acid selected from the group consisting of acid precursors of hydrotropes, acid precursors of anionic surfactants (a), and mixtures thereof; and (f) a weak acid; wherein the pH of the detergent gel is between 7.0 and 7.5, and wherein the total amount of surfactants (a)+(b) in the detergent gel is from 15% to 70% by weight of the gel.

2. A detergent composition according to Claim 1 wherein the strong acid is selected from the group consisting of linear alkylbenzene sulfonic acid, alkyl sulfuric acid, ethoxylated alkyl sulfuric acid, and mixtures thereof.

3. A detergent composition according to Claim 1 wherein the strong acid is an acid precursor of a hydrotrope selected from the group consisting of cumene sulfonic acid, xylene sulfonic acid, toluene sulfonic acid, 2-ethyl-hexyl sulfonic acid, and mixtures thereof.

4. A detergent composition according to Claim 1 wherein the weak acid is selected from the group consisting of citric acid, malic acid, maleic acid, succinic acid, formic acid, and mixtures thereof.

5. A detergent composition according to Claim 1 wherein the pH of the composition is between 7.0 and 7.4.

6. A detergent composition according to Claim 1 which is a dishcare detergent.

7. A detergent composition according to Claim 2 wherein the strong acid is a linear alkylbenzene sulfonic acid.

8. A detergent composition according to Claim 4 wherein the weak acid is citric acid.