US2738365A - Process of producing a synthetic detergent of good color - Google Patents

Description

United States Patent C PROCESS OF PRODUCING A SYNTHETIC DETERGENT OF GOOD COIDR Herbert Smith Sylvester, Leonia, N. 1., or to Colgate-Palmolive Company, a corporation of Delaware No Drawing. Application October 31, 1952, Serial No. 318,081

6 Claims. (CL 160-505) The present invention relates to a process of producing a synthetic detergent of good color from water-soluble salts of organic sulfuric acid reaction products.

In the manufacture of synthetic detergents of the sulfonate and sulfate types, organic compounds are treated with a sulfonating agent, e. g., oleum, to produce an organic sulfuric acid ester or an organic sulfonic acid which is then neutralized with a suitable base to form a water-soluble salt. Frequently the salts so obtained are not as light in color as desired and a bleaching operation is resorted to in order to obtain products of good color. The present invention provides a bleaching operation for producing synthetic detergents of good color which is simple and economical.

In accordance with the invention, the process of producing a synthetic detergent of good color comprises admixing a water-soluble silicate and an alkaline hypochlorite with an aqueous slurry of a water-soluble salt of an organic sulfuric acid reaction product. The water-soluble silicate and the alkaline hypochlorite exercise a synergistic bleaching of the water-soluble salt of the organic sulfurica'cid' reaction product, i. e., the bleaching of the syntheticdetergent obtained in the presence of both of these agentsis surprisingly greater than could be predicted from the effect of each of these agents individually. Moreover, the mixture of the three ingredients is found to be mudfi'less earr'dswianetanic equipment than a mixture of 'the'detergent and the hypochlorite in the absence of the silicate. The viscosity of the mixture also is considerably lower in the presence of the silicate which is of definite advantage in pumping and spray drying rhe-aqueousslum.

The present inventiompa'fiic'ularntility-in'thepreparation of alltyl aryl sulfonates of good color but it may also be applied in the preparation of synthetic detergents of all of the organic sulfuric acid reaction products which, after neutralization, possess detersive properties. As those skilled in the art already know, these organic sulfuric acid reaction products which possess detersive properties are generally characterized by the presence in the molecule of a higher alkyl chain having about 8 to 22 carbon atoms per molecule, and ordinarily preferably within the range of about 12 to 16 carbon atoms. In the case of the alkyl aryl sulfonates, the aryl group may be mononuclear or polynuclear and it may be further substituted with short alltyl chains or may be substituted with bydroxyl groups or it may be essentially unsubstituted. Typical examples are dodecylbenzene sulfonate, dodecylnaphthalene sulfonate, tetradecyl toluene sulfonate, etc. Another well-known type of synthetic detergent which may be treated in accordance with the present invention is a water-soluble salt of the sulfuric acid ester of higher fatty acid monoglycerides, such as sodium salt of sulfuric acid ester of coconut oil fatty acid monoglycerides. A further well-known type of synthetic detergent is the sulfuric acid ester of higher fatty alcohols derived from coconut oil or other fatty acids within the range of carbon atoms specified hereinabove. These specific exam- 2,738,365 Patented Mar. 13, 1956 ples of various detergents are given purely for the purpose of illustration and not for the purpose of limitation since the present process is applicable to the preparation of detergents of good color from sulfuric acid reaction products of all organic materials which, after neutralization, possess detersive properties.

Any of the alkaline metal hypochlorites may be used in the process of the present invention but, generally speaking, sodium hypochlorite is much preferred because of its effectiveness, its relatively low cost, and the fact that most detergent compositions which will be treated in accordance with the present invention are sodium salts of the sulfuric acid reaction product. Other hypochlorites which may be used satisfactorily include lithium h hl grite and potassium h o c hlorite. wi 5 0mm.- silicates mcli ar e sed in the process of the present invention may be any of the alkaline silicates including sodium and potassium silicate but in general it is preferred to use sodium silicate because of its effectiveness, its relatively low cost, and the fact that most of the detergents which will be treated in accordance with the present invention are sodium salts of the organic sulfuric acid reaction products. While any water-soluble alkaline silicate may be used, certain ratios of the alkaline oxide to silicon dioxide are found to be of particular advantage. In the case of sodium silicate the NazOzSiOz ratio may vary from about 1 22 to 1:3.25.

The amount of water 'soluble silicate, based upon the quantity of synthetic detergent solids used, may vary from a small but effective amount of the order of about 1% up to any desired amount present in the composition. Generally speaking, about 5 to 10% of silicate is the maximum amount required in the composition for controlling the viscosity and for protecting the equipment against corrosion and for exercising its synergistic effect with the sodium hypochlorite in the bleaching of the detergent. The amount of hypochlorite used may also vary widely from a small but effective amount of the order of about 0.1% up to about 5% by weight of the active ingredient. These ratios are not critical in the sense that there is a sudden change in the bleaching efiect below or above the indicated range but within the indicated range good results are assured by following the process of the present invention. While it is preferred that the silicate be admixed with the detergent slurry prior to the introduction of the hypochlorite material, this order of addition is not absolutely essential and they may be introduced simultaneously or the hypochlorite may be introduced a short period of time prior to the introduction of the silicate but inasmuch as the hypochlorite may cause some corrosion in the apparatus prior to the introduction of the silicate, this order of addition is not preferred.

The process may be carried out batchwise or continuously.

In carrying out the process of the invention batchwise, a slurry of the water-soluble salt of the sulfuric acid reaction product in water is placed in a suitable vessel, e. g., a vessel made of austenitic stainless steel, and the formula amount of silicate is then admixed therewith by any convenient stirring or agitating mechanism. When the silicate has been blended with the aqueous slurry of the synthetic detergent material, the sodium hypochlorite is then introduced with thorough mixing. The bleaching effect is produced by the joint presence of the silicate and the hypochlorite and the resulting composition, after standing for a suitable time to permit the reaction to go at least substantially to completion, is then ready for procg wwewiment. The time is not critisince the major proportion of the bleaching is accomplished relatively quickly; e. g., in 30 to minutes, but longer periods up to several hours may be used, if de- 3 sired. Generally speaking, these detergents are prepared in M dried form and the treated composition as de- I- 1. ready for admixing in a suitable crutcher with other ingredients desired in the final composition and for spray drying.

In the continuous process a stream of the aqueous slurry of the synthetic detergent is pumped through a line from a suitable storage tank to a suitable receiving tank. Into this flowing stream of the aqueous slurry of the detergent material a stream of silicate is pumped with suitable proportioning means so as to introduce the silicate material into the stream of detergent at a rate calculated to give the formula proportions of these two ingredients in the mixed stream. Thereafter a proportioned stream of the solium hyprochlorite is pumped into the mixture of silicate and detergent at a rate calculated to introduce the formula amount of hypochlorite into the mixture. The flow conditions in the pipe must be regulated so as to give good stirring either inherently fmm turbulent flow or aided by mechanical stirring devices in the line. The mixture of three ingredients goes into the receiving tank where it is held for a time sufficient at least substantially to complete the reaction before it is pumped to the crutcher for further processing.

The following table illustrates the synergistic efiect of the treatment of an aqueous slurry of synthetic detergent material (50% by weight of water and 50% by weight of detergent solids) with sodium hyprochlorite and sodium silicate jointly as compared with the effects of treatment of the same material with these agents individually, the time of treatment in each case being three hours:

The N-silicate referred to in the foregoing table was added as an aqueous solution or slurry containing approximately 38% solids and the ratio of NazOzSiOa was 1:3.22. The synthetic detergent was the sodium salt of dodecyl benzene sulfonate obtained by polymerizing propylene to obtain the tetramer, condensing this polypropylene with benzene, sulfonating the condensate and neutralizing the sulfonic acid. The detergent was about 88% active ingredient and 12% sodium sulfate.

When the silicate is present, the proportion of sodium hypochlorite required to produce a given bleaching effect, as noted in the table, is very materially reduced as compared with the proportion required when no sodium silicate is present at the time of treatment. This clearly demonstrates the synergistic efiect of the silicate upon the hypochlorite since the effect of the silicate itself on the alkyl aryl sulfonate was relatively slight.

5 The following table illustrates the eifect of the silicate on the viscosity of a 50% aqueous slurry of the same type of synthetic detergent referred to in Table I:

1 Determined in a Brooktield viscosimeter.

Having thus described the invention, what is claimed is: 1. The process of producing a synthetic detergent of good color which comprises admixing a water-soluble alkali metal silicate and an alkali metal hypochlorite with an aqueous slurry of a water-soluble salt of an organic sulfuric acid rection product possessing detersive properties, said ilicate and h hlorite being used in amounts ient t e ea ng c said salt and a reduction in viscosit 0 said aqueous slurry of organic sul 1c acid reaction product.

2. The process as set forth in claim 1 in which the water-soluble salt is an alkyl aryl sulfonate.

3.Theprocessassetforthinclaimlinwhichthe water-soluble silicate is a sodium silicate having an NazOzSiOz ratio of about 1:2 to 1:33.25.

4. The process as set forth in claim 1 in which the alkaline hypochlorite is sodium hypochlorite.

5. The process as set forth in claim 1 in which the water-soluble silicate is used within a range from a small but effective amount up to about 10% by weight of the water-soluble salt.

6. The process as set forth in claim 1 in which the alkali metal hypochlorite is used within a range from a small but effective amount up to about 5% of the watersoluble salt.

References Cited in the file of this patent UNITED STATES PATENTS 1,931,245 Banigan Oct. 17, 1933 2,333,830 Toone Nov. 9, 1943 2,566,501 Smith et al Sept. 4, 1951 OTHER REFERENCES Carter: Ind. and Eng. Chem., vol. 18 (1926), pp. 248-252.

SchwartbPerry: Surface Active Agents (1949), p. 123.

Claims (1)

1. THE PROCESS OF PRODUCING A SYNTHETIC DETERGENT OF GOOD COLOR WHICH COMPRISES ADMIXING A WATER-SOLUBLE ALKALI METAL SILICATE AND AN ALKALI METAL HYPOCHLORITE WITH AN AQUEOUS SLURRY OF A WATER-SOLUBLE SALT OF AN ORGANIC SULFURIC ACID RECTION PRODUCT POSSESSING DETERSIVE PROPERTIES, SAID SILICATE AND HYPROCHLORITE BEING USED IN AMOUNTS SUFFICIENT TO EFFECT BLEACHING OF SAID SALT AND A REDUCTION IN VISCOSITY OF SAID AQUEOUS SLURRY OF ORGANIC SULFURIC ACID REACTION PRODUCT.