US2738332A - Process of treating soap particles - Google Patents

Description

United States Patent 2,738,332 PROCESS OF TREATING SOAP PARTICLES Russell Edward Compa, Bogota, N. J., assignor to Colgate-Palmolive Company, Jersey City, N. .J., a corporation of Delaware N Drawing. Original application December 20, 1943, Serial No. 515,025, now abandoned. Divided and this application July 21, 1948, Serial No. 40,017

2 Claims. (Cl. 252121) The present invention relates to a process of treating soap particles to minimize dust and/or to reduce the tendency of the soap to lump in use. More particularly, the invention relates to a process of applying. a detergent of the sulphonate type having a single long chain aliphatic radical per molecule to the surface of spray-dried soap particles, and to the coated product.

Soap preparations have been employed for many years both in industrial and in domestic use in the form of particles of relatively small dimensions, for example, spray-dried soaps, granulated soaps, soap powders, soap chips, etc. Because of their large exposed surface area, soap particles possess certain advantages over soap in massive form, such as bars and cakes, a principal advantage being rapid solubility in water. There have been, however, some disadvantages associated with soaps in particulate form. One disadvantage is that these soaps contain varying amounts of extremely fine particles. Some of the fines are incidental to the manufacture of soap in the form of particles, whereas others result from the breakdown of larger particles in handling, packaging, shipping, etc. Some of the fines are so small that they float in the air as dust when the soap is shaken in its container or poured from the container. This dust is objectionable not only because it represents a waste of soap but also because it is irritating to the mucous membranes of persons who have breathed the dusty air, causing sneezing, running of the eyes and nose and other discomforts. Another disadvantage of soaps in particulate form is that when they are poured onto the surface of water, particularly heated water, lumps or agglomerates form which are very difiicult to break up and dissolve in water. This tendency is particularly evident in spraydried soaps.

I have discovered that by applying a detergent of the sulphonate type having a single long chain aliphatic radical per molecule to the surface of soap particles, the foregoing disadvantages are overcome or greatly reduced.

Generally speaking, the process of the present invention comprises applying an aqueous solution of the detergent to the surface of soap particles and drying the applied material.

The soap particles treated in accordance with my invention may be made of various compositions, e. g., sodium soaps of fatty acids, with or without fillers, builders, emulsifiers including mineral oil, etc., and may be formed in any suitable manner, for example, by granulating framed or milled soap, by drum drying soap solu tions to form flakes, chips and like forms, by spray-drying soap solutions, etc. Spray-dried particles in the form of beads, that is, soap which has been sprayed under such conditions as to form one or more voids within the particles of soap, are particularly susceptible to the formation of lumps when the soap is poured onto hot water.

A satisfactory method of applying the detergent in accordance with the present invention comprises spraying an aqueous solution of the detergent on the soap particles, preferably with the aid of agitation, and drying the sprayed particles, i. e., removing sufiicient water from the sprayed material to leave the coated "particles in substantially nontacky or free-flowing condition.

r6 Ice The coating materials contemplated by the invention are water-soluble salts of organic-substituted, polybasic, oxygen-containing inorganicsulphur acids, i. e., sulphates and sulphonates which contain a single long chain aliphatic radical per molecule, and they are preferably of the type known as organic sulphonate salts, that is, salts of an organic sulphuric or true organic sulphonic acid. Where reference is made in the specification and. claims to compounds of the sulphonate type or to sulphonate compounds, it is to be understood that both sulphuric and true sulphonic compounds are included. The organic elements with which the inorganic acid radical is combined may have not only organic substituents, such as alkoxy, acyloxy and ketonic groups, etc., but may also have inorganic substituents, such as ttnesterified hydroxyl groups, thiosulphates, halogens, halogenoids including cyanides, cyanates, thiocyanates, etc., and the like. The organic sulphonate salts are preferably produced by neutralization with bases or alkalies of the products of the sulphation or sulphonation of various materials, including saturated and unsaturated carboxylic acids, mineral oils, mineral oil extracts, monoand di-glycerides, partial esters or ethers of polyglycerols, esters or ethers of glycols, polyglycols and polyalcohols, alkylated aromatic compounds, long-chain alcohols and olefines, and numerous other organic compounds and mixtures of compounds.

These organic compounds, the sulphates or sulphonates of which may be neutralized as aforesaid with an alkaline or basic material, can be sulphated or sulphonated by any of several methods and may form any of several products, depending upon the method of sulphation or sulphonation employed. The sulphated or sulphonated organic compounds include sulphonated mineral oil, conventional mineral oil refinery sludges; sulphonated mineral oil extracts, including the products described in U. S. Patents Nos. 2,149,661; 2,149,662 and 2,179,174; sulphonated fatty acids including sulpho-ricinoleic acid and sulpho-oleic acid; long-chain aliphatic sulphonates and sulphates, including cetyl sulfuric acid, dodecyl acid sulphate, and tetradecenehydroxy sulphonic acid-1, 2; aliphatic ether and ester sulphonates, including the dodecyl ether of hydroxy ethyl sulphonic acid, the cetyl ether of glyceryl sulphonic acid, tallow monoglyceride monosulphate, and coconut oil fatty acid monoesters of beta methyl glycerine sulphonic acid; sulphonates prepared by treatment of organic materials with sulphur dioxide and chlorine in the presence of light and hydrolysis of the product; sulphonates prepared by treatment of organic bodies with sulphuryl chloride and an activating agent in the presence of light and hydrolysis of the product; fatty acid amides of amino alkyl sulphonic acids, including lauric amide of taurine and tall oil acid amide of amino glyceryl sulphonate; alkylated aromaticsulphonic acids, including dodecyl benzene sulphonic acid, and octadecyl naphthalene sulphonic acid; the prod uct of a mineral oil extract sulphonated while dissolved in liquid sulphur dioxide; and innumerable other organic sulphonic and sulphuric acid derivatives or mixtures thereof.

The detergent may be used singly or in combination and in pure form or together with other materials. Many of the commercially available synthetic detergents contain inorganic salts, e. g., sodium salts of organic -sulphates and sulphonates usually contain relatively large percentages of sodium sulphate, often as high as 60% to 70%.. These inorganic salts do not interfere with the functioning of the active ingredient in preventing lumping. Some wetting agents tend to become brittle when dry, and it is advantageous in such instances to include a binding agent in the coating to reduce its tendency to breakin'the subsequent handling and transportation of the product and produce objectionable dust. Suitable binding agents include water-soluble siliceous ma-terials, e. g., sodium silicate; alkali metal phosphates, e. g., disodium dihydrogen pyrophosphate; alkali metal borates, citrates, etc.; starch, gums, waxes (including a water-soluble polymerized ethylene oxide), mineral oils, polyhydric alcohols such as glycol, glycerol, sorbitol, mannitol, etc.; fatty'acids, mono and di-esters of fatty acids, fatty oils, etc. The binding agent may be dissolved, dispersed or emulsified in the solution of the detergent and be ap plied simultaneously therewith, or it may be sprayed separately as a liquid or solution in a suitable solvent before or preferably with or after the application of the detergent.

Various methods of agitating the soap particles, so that at least .a major portion of the surface of the particles is exposed to the spray of the aqueous solution of the coating material, may be used. One method is to spread the particles out on a fiat surface which is then shaken or vibrated to cause the particles to change position. Another method is to cause soap particles to flow down an inclined surface or to cascade through the air and simultaneously to spray them wtih the solution of the detergent. A preferred method for large scale operations is to spray the soap particles in a dim which is rotated at suflioient speed to cause the particles to tumble during the spraying operation. The detergent may be applied in dry condition to the surface of wet soap particles, e. g., as a cloud in the spray tower or in a rotating drtun, but ordinarily, it is preferred to use a solution. The term solution is used in this specification not only to include true solutions but also colloidal solutions and suspensions.

The solution of detergent may be sprayed on the soap particles simultaneously with the agitation, or the spraying and agitating steps may be carried out alternately with any desired number of repetitions.

In most cases -it will be necessary to dry the coated particles after the spraying operation to evaporate the solvent in which the applied material was dissolved. Any suitable method of drying may be employed. For example, the coated particles may be spread out in a thin layer to dry or, where they are coated in revolving drums, they may be satisfactorily dried ,by continuing the rotation of the drum after the spraying operation either with or without forced circulation of air through the drum.

The following examples are given for the purpose of illustrating the principles and advantages of the present invention, but it will be understood that the invention is not limited to the use of the apparatus, procedure and .materials employed in the illustrative examples.

Example I Soap particles are formed by spray-drying a hot aqueous solution of about 70% sodium salts of fatty acids and 30% soap builders. The spray-dried product containing about moisture is composed largely of hollow beads but it contains fines that form a cloud of dust when the soap ispoured or shaken. Five hundred (500) parts by weight of this spray-dried soap are placed in a rotatable drum having an opening in one end. The drum is rotatedat a suflicient speed to cause tumbling of the soap particles. While the rotation of the drum is continued, 12.1 parts of an aqueous solution of the ammonium salt of a mixed (or coconut oil) fatty acid monosulphate monoglyceride are sprayed on the tumbling particles. The tendency of the soap particles to lump when poured on the water is reduced by this treatment.

Example II test was set up for comparing the tendency of the soap particles to lump before and after treatment. In this test 15 grams of the soap to be tested are poured upon the surface of a liter of water at 50 C., allowed to stand one minute and then vigorously stirred for 10 seconds. The resulting mixture is poured through a 10 x 10 mesh per inch screen, the foam blown away, and the material retained is weighed in its wet condition. The weight of the retained material, which is taken as an index of the lumping tendency, is about 30% heavier when the untreated material is testedthan when the material treated as described in this example is tested.

Example III Five hundred (500) parts by weight of a spray-dried soap similar to that usedin Examples I and II are sprayed in a rotating drum as described in these examples with about 72 parts of a 23.5% solution of a synthetic detcrgent containing about 36% sodium sulphonate of oleic acid ester of aliphatic compounds and the balance largely sodium sulphate. When subjected to the comparative test described under Example ll with untreated soap particles, it is found that the material treated as described in this example has reduced tendency to form lumps.

The amount of the detergent applied may vary over a wide range. Since it is a surface coating, small amounts on the order of 0.01% on a dry basis give significant improvement in dust reduction but somewhat larger amounts preferably are used where the tendency of the soap to lump when poured into hot water is pronounced. Relatively large amounts of the order of about 10% may be used, but when more than about 3% is used, there is no significant added improvement due to the ex cess, either in minimized dust or in reducing tendencies to lump. Preferably about 0.1% to about 2.5% is used. The concentration of the solution in which the detergent is sprayed may be varied over a broad range. It is preferable to use a solution of such concentration that the solution has good spraying and spreading properties but not so dilute as to add sufiicient water to cause solution of the soap particles in applying the desired amount of detergent. The use of excess water, moreover, is wasteful of the heat required to dry the coated product to the proper moisture content.

The present application is a division of application Serial No. 515,025 filed December 20, 1943 and now abandoned.

Although the present invention has been described and illustrated in connection with certain specific embodiments, it will be understood that modifications and variations within the scope of the following claims are contemplated.

I claim:

1. A process which comprises spraying on the surface of preformed water-soluble soap particles with the aid of agitation an aqueous solution of a water-soluble salt of a higher fatty acid monosulfatc monoglyceride and drying the particles whereby the tendency of soap particles to form lumps when poured into heated water is reduced.

2. As a new article of manufacture water-soluble soap particles having a coating of a water-soluble salt of a higher fatty acid monosulfate monoglyceride, said coated particles having less tendency to form lumps when poured into heated water than uncoated particles.

References Cited in the file of this patent UNITED STATES PATENTS 2,329,694 Bodman Sept. 21, 1943 FOREIGN PATENTS v 553,735 Great Britain June 3, 1943 OTHER REFERENCES The Perfumery and Essential Oil Record, July 1943, pages 203-204.

Claims (1)

1. A PROCESS WHICH COMPRISES SPRAYING ON THE SURFACE OF PREFORMED WATER-SOLUBLE SOAP PARTICLES WITH THE AID OF AGITATION AN AQUEOUS SOLUTION OF A WATER-SOLUBLE SALT OF A HIGHER FATTY ACID MONOSULFATE MONOGLYCERIDE AND DRYING THE PARTICLES WHEREBY THE TENDENCY OF SOAP PARTICLES TO FORM LUMPS WHEN POURED INTO HEATED WATER IS REDUCED.