US2776943A - Treatment of soap particles - Google Patents

Description

United States Patent O TREATMENT OF SOAP PARTICLES Stanley L. Eaton, Cincinnati, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, at corporation of Ohio No Drawing. Application May 14, 1951, Serial No. 226,293

16 Claims. (Cl. 252-109) The present invention relates to an improved type 'of soap particles and methods for preparing same and particularly relates to a process for reducing the balling tendencies of silicate-containing soap particles.

Soap products in particulate form such as spray dried soaps, powdered or ground soaps, granules, etc. that are prepared from fat formulas having little or no fatty matter derived from oils of the coconut oil group, have a tendency, when added to warm water, to form difficultly soluble masses or aggregates of the individual particles be fore solution of the soap can be efiected. This tendency which is sometimes referred to as balling is characteristic of many of the products on the market today. While balling is increased in part by variables such as decreased moisture and increased bulk density of the product, it is dependent to a greater degree on the fat formulation prior to saponification. Thus, the use of large amounts of oils of the coconut oil group in the fat formula has generally been the most effective means of controlling the balling tendency. Heretofore, numerous methods of particle treatment have also been proposed for reducing or eliminating balling, including surface application of materials such as glues, starches, water, wetting agents gums and mineral oils. However, as far as I am aware these procedures have not met with commercial success, primarily because the performance of the product in sudsing and detergency is adversely afiected by the large amount of material required to achieve desired improvement in balling.

It is an object of this invention to produce silicatecontaining soap products having reduced tendency to ball.

It is a particular object to produce built particulate silicate-containing soap products that are substantially free of balling tendencies.

It is another object to produce built particulate silicatecontaining soap products that are substantially free of balling tendencies without adversely affecting the dissolving, cleansing and sudsing performance of the soap.

Other objects of this invention will be apparent in the course of this description.

I have discovered that the above objects can be achieved by applying to the surface of the soap particles a minor amount of fatty acid having from 8 to 14 carbon atoms in the molecule, or mixtures consisting predominantly of such fatty acids, and thereafter eifecting reaction between the fatty acid and silicate at the particle surface. I have further discovered that of the fatty acids thus employed the saturated Cs-C fatty acids appear to be the most effective and that mixtures of fatty acids of oils of the coconut group as defined below and which contain appreciable amounts of saturated C8 to Cux fatty acids give excellent results. H

In the practice of my invention, the application of the fatty acid to the particle surface can be practiced in numerous ways, as for example, by spraying the fatty acids onto the silicate-containing soap particles while the latter are agitated to insure relatively uniform distribution on the majority of the particles. Thejapplication can also of the fatty acids.

2 be effected by passing the soap particles through a mist Numerous other methods will become apparent to those skilled in the art during the course of this description.

The unusual efiectiveness of this process in reducing balling tendencies appears to be achieved by a mixture of reaction products of the fatty acids with silicates at the surface of the particles, which I shall call soap-silicate complexes, which possess outstanding effectiveness in the reduction of balling tendencies. I have found that my invention is particularly efiective in the treatment of soaps which contain 1 /2% or more of sodium silicate. Under the microscope this complex looks like a thin crust on the soap particle. It has outstanding properties with regard to preventing the formation of gels that cause balling when the particle is contacted with warm water. It appears that the beneficial action of this crust-like complex is in part due to a combination of factors resulting from (1) the removal of MezO from the silicate molecules by the fatty acid to form C3 to C14 soaps and (2) the resulting high SiOz/MezO ratio in the silicate portion of the soap-silicate complex formed thereby, wherein Me is used to designate an alkali metal.

My invention is of value in that it lowers the amount of oils of the coconut oil group that would be otherwise required to manufacture soaps of like balling tendencies. Thus I have found in general that in the treatment of silicate-containing soap granules with fatty acids derived from coconut oil, each percent or" the fatty acids in the range of l5% used according to my invention effects an improvement in balling equivalent to that obtained by increasing the coconut oil content about 7 to 10% in the fat mixture used for preparing the soap. Thisenables the manufacturer to greatly reduce his overall usage of coconut type oils, and is of particular economic value when the supply of coconut type oils is short as during war time.

By the term oils of the coconut oil group, I mean vegetable seed oils or fats at least 50% by weight of the combined fatty acids of which are lauric and/or myristic acids. These oils (many examples of which are given in Hilditchs The Chemical Constitution of Natural Fats, 2nd Edition (1947), pages 198-205) are commonly derived from the seed of members of the botanical families Lauraceae (Tangkallak kernel oil, for example), Myristicacaea (Ucahuba nut oil for example), Vochysiaceae (Jaboty kernel oil for example), Salvadoraceae (Khakan kernel oil for example), and more especially the Palmae family. Coconut oil is the outstanding example of an oil derived from seeds of the Palmae family, but other non-limiting examples of such oils are oils of murumuru kernel, tucuma kernel, cohune nut, ouricoury nut, babassu kernel and palm kernel.

It is to be understood that the specific fatty acids used in the process of my invention need not originate in the above mentioned oils; fatty acids from other sources may also be used, such as for example, synthetic fatty acids prepared by oxidation of petroleum or by hydrogenation of carbon monoxide by the Fischer-Tropsch process, which contain appreciable amounts of C3 to C14 fatty acids.

The following balling test has been used in evaluating the improvement effected by employing the process of the present invention:

I Bailing test cc. of the particulate soap under test were dropped through a funnel having a inch diameter bottom Dilution and agitation of the mixture was then efiected by directing a stream of water (temperature-120 F.) I

untreated granules produced from similarly built soaps made frorn'oils containing from 40% to about 45%" coconut oil."

' ExamplgrZ-A neat soap composed of the sodium salts ithrough anozzle (consisting of a Bunsen burner wing tiphaving an orifice 3 1 inches wide and 1%"inches long) oil and 84% of tallow and grease was crutched with builders and spray dried in conventional manner to give a granular product containing 62% real soap, 18%

toward the mixture in the pan; The nozzle formed a- 5 sodiumsilicate solids having a SiOz/NazO ratio of about sheet of, water' which hit the soap-Water mixture at an 2.5/1, 6% tetrasodium pyrophosphate and 13% moisture. angle of about 45 with the vertical and along a line The granules hadv a bulk density of 0.41 gms. per cc. radial from the center of the pan, thereby causing a sWirl- 96 parts of these granules were treated by spraying 4 ing action in the water. In this mannergl gallonof parts .of molten (temperature. about 125 F.) mixed water was. added over a' period of .40 seconds. Theflo fatty acids (obtained by the hydrolysis of coconut oil) final mixture of soap and water was then poured onto a upon the surface of the granules while the granules were tared 20' mesh screen. The gummy mass of balled soap tumbled in a rotating drum. The temperature of the granules which was retained on the screen was weighed granules during the latter step was on the order of 100 and the'weight recorded in grams as the balling grade. F. As an immediate result of the fatty acid application, Such balling grades are determined on badly balling soap 15 the granules decreased about 0.06 gm./ cc. in bulk density products will run from about 100 gms. to) about :1 0 andhad a soft, tacky feel. However, after 15 minutes gms., whereas soaps that are considered to be substanreaction time during which period there was substantially tially free of balling will have .a rating of about 30 gins." no change in the temperature, the density of the granules and under when evaluated according tov this'test. was again about 0.41 gms/cc'. and the granules were less j e The invention will be more clearly understood from dusty and more free flowing than prior to the application the following examples in which parts and percentages of the fatty acid.

are by weight: Samplesof the treated and. untreated soap granules Example li -Neat soap was prepared by customary' were subjected .to the balling test. The table below 'saponification with caustic soda of a glyceride mixture s'hows'the results of two runs made in' accordance with consisting of 27% coconut oil and 73% of a mixture of the example. i I beef tallowand hog grease, This soap was crutched with i builders and spray dried in conventional manner (i. e. Bamng Grades of. dried by spraying the crutched soap in particulate form Granules ina stream of hot air) to give a granularproduct con- Run taining 74% real soap, 11% sodiumsilicate solids having 30 q tr t d t gf a SiOz/NazO ratio of-about 2.6/1, 6% tetrasodiumpyro- QE phosphate and 8% moisture. Its bulk density was about Acids 0.35 gm./cc. 98 ipajrts of these granules were treated grams by spraying 2 parts of mixed fatty acids, obtained by the. 105 32 I hydrolysis of coconut oil, upon the surface of the granules 5 2 I "I: 93 35 1 while the granules were agitated bytumbling in arotating' drum. The temperature of the soap ranules during the T i u latter step was maintained at approxii iately 100 F. and Y i g a soap composFd ofthe'spdlum Salts 7 the temperature of the. fatty. acids sprayed thereon was Git C any am 8 denved a mixture of i aboutv 120 F: V The. application of the fatty acids at the: 40 m1 and 97% of tal-1 ow nd grease-Was .crutched wlth 12mmhstart caused the granules to' have a'softmealyand some. ers i Spray dned .convenuonal manner to Y a Y 'what tacky nature and the bulk density decreased; Howil ploduct gfg fi soap 18% slhcate ever, this change was. strictly temporary and after 20' i S 2/ g i 6% minutes storage time without substantial change in tem 6 fi 2 a 2 molsture' The Zp'erature, during which period the fatty acids reacted with 5 g i es a u ienslty-bo pans of the silicate at the surface of the particles to form the ese granu es were'treafied y sPraymg 4 paitspf moi-Item soap-silicate complex, the density had increased to sub (temperature l 100 lmxedfatty aclds (qbtamfad istantially its former value. The soft mealy feel had also the hydrolysls of coconulloll) the granules whfle disappeared and the product was actually less tacky and the'granul? w tumbled a rotatmgfldmm' The x more free flowing than it was before being sprayed with g 3 granules qunngfihe latter step was Th thefatty acids. The table below shows the marked imor er 0. a bul'k 2 21-11 lmmedlate resultof the aprovement produced in the balling grade of the product, g gg t of the granules decreased about V wherein the results ofthree separate operations, each conan the granules: pad mealy apducted as described above, are shown ,7 I pearance. However, after 15 minutes storage without Samples of the treated and untreated soap. granules i ij z Zg m temgerature the densllty had were subjected to the above described balling test with o gmsJcc' an h granules were less dusty the, following results I I tougher, and more free flowing than they were before a being sprayed with fatty acids.

' M Samples of' the treated and untreated'soap granules Balliflg G d of were subjected" to. the balling test. The table below Granules shows the results of'two runs made in accordance with Run N0. the example. v Treated Untreated, with grams Belling Grades of grams Granules Run'No. 1 46 a 17 Treated 2 43 1 Untreated, .With'FB-Y' 3 55 15, E c ds, gms;

The balling grades of the treated soap granules in this 123' v 25 instance were as good as those normally obtained with 7 42 Essentially the sameresult's can be obtained when thegranules of-the above examples are sprayed with'fattyf acids' derived fromupalm kernel oil.

I have also found that a mixture of lower fatty acids as may be derived by fractionating fatty acids of oils of the coconut oil group, are particularly effective in reducing the balling tendencies. C fatty acids alone are also outstandingly effective as is shown in the following example.

Example 4.-Soap granules were prepared in the same manner as described in Example 3 except that 3 parts of molten capric acid (a C10 fatty acid) was used instead of coconut fatty acids for treating 97 parts of the soap granules at room temperature. The following data show the very marked improvement in balling grades, 2. substantially non-balling product being obtained.

Attention is called to the fact that by the reaction of the fatty acids with silicate at the surface of the soap particles, and the resultant formation of high SiOz/NaaO ratio silicate-soap complexes, a material having detergent and sudsing power is formed, thereby avoiding the detrimental effect characteristic of earlier processes wherein the soaps were merely coated with inert materials or even materials that repressed the sudsing and detergent properties of the soap.

It is the saturated fatty acids containing from 8 to 14 carbon atoms that are particularly useful in my process. Whereas the mixed fatty acids obtained from oils of the coconut oil group contain minor amounts of unsaturated fatty acids, such as oleic and linoleic, the main value of these unsaturated fatty acids lies in their low melting points and their liquifying or solvent effect on the higher melting saturated fatty acids. Highly unsaturated and high molecular weight fatty acid mixtures, such as commercial oleic acid (commonly known as red oil) and the mixed fatty acids derived from cottonseed oil, are practically ineffective as compared to the fatty acid mixtures derived from oils of the coconut oil group for the purposes of my invention.

It is to be understood that I contemplate the use of other builders along with the water-soluble silicates in the practice of my invention. Examples of such other soap builders are the Water-soluble pyrophosphates (e. g. the sodium pyrophosphate used in the above examples), carbonates, orthophosphates, tripolyphosphates, borates, etc. Whereas the more alkaline of such builders may also neutralize some of the fatty acids applied in this process the soaps produced therewith have not been found to detract from the benefits obtained with the soap-silicate complex.

In the practice of this invention, I prefer to employ soap compositions containing at least 1 /2% by weight of silicate solids, which may be derived from a wide variety of water-soluble silicates. Sodium silicates having SiOz/NazO ratios varying from 2.0/1 to 4.0/1 can be used in the preparation of soap granules treated in this invention. In general, however, I prefer to employ silicates having ratios in the range of 2.3/1 to 3.3/1.

I may also employ alkaline materials such as caustic soda or soda ash in conjunction with the silicate to modify the ratio of the silicates. Sometimes the builder contents of commercial soap preparations are composed entirely of silicate solids but the silicate solids usually do not exceed about 50% of the Weight of the soap product.

I usually prefer to treat the soap particles with amounts of fatty acids in the range of 25% of the weight of the soap particle. In this range optimum benefits are obtained. However, smaller amounts can be used to advantage, as for example, the use of 1% fatty acids is often desirable, particularly in soap containing small amounts of silicate. Although the reduction in balling obtained per unit of fatty acid is somewhat less when about 7% or more fatty acid is used, larger amounts, as for example 8 to 9%, can be applied successfully in some instances, particularly when the soap is built with large amounts of silicate and when the temperature of the granules is in the neighborhood of or below the melting point of the fatty acids. However, when low temperatures are used the efficiency of the process may be somewhat reduced since the reaction of the fatty acids with the silicate in the soap granule is retarded; however, even under such conditions a marked improvement in balling is observed in the treated granules.

In the practice of thisinvention, the fatty acids can also be mixed in powdered form with the soap granules. However, in so doing or when molten fatty acids are applied to cold soap particles, e. g. at temperatures below 50 F., the temperature of the soap particles is preferably increased at some point in the process so that the fatty acids will melt and be absorbed at the surface of the particles to insure reaction with the silicate. If the use of low temperatures of application are desirable the fatty acids can be sprayed onto the particles in solution in solvents such as ethyl alcohol, thereby promoting absorption and subsequent reaction. In other words in order to obtain the full benefits of my invention it is highly desirable to have the fatty acids in a fluid or liquid condition during or at least at the start of their reaction with the silicate in the soap; i. e. either at a temperature high enough to liquify the fatty acids with or without the aid of solvents or other liquifying media or compositions. The mixed fatty acids from coconut oil, for example, are in a liquid form at 75 F., even though some of the fatty acids contained therein are normally solid in the pure form at that temperature.

In general to facilitate the operation I prefer to carry out my process in a manner such that the granules to which the fatty acids have been applied will not drop substantially in temperature during the subsequent reaction period. In such cases I prefer to spray the fatty acids in molten form (preferably over F.) onto soap particles having a temperature of at least 50 F., and preferably over 80 F., While tumbling the soap particles in a rotating drum, followed by storing the soap particles in bulk, as for example in large buggies or bins. The period of time consumed in normal operations such as screening, weighing, and transferring the product to and from storage in addition to the storage period is usually many times greater than the few minutes in which substantially complete reaction of the fatty acids and silicate occurs. Operating in this manner, and by keeping the temperature below the point at which the product begins to soften or melt (generally not over F), agitation need not be resorted to during the reaction-storage period for the purpose of avoiding lumping or caking. However, the fatty acids can be applied to hot particulate products such as freshly spray dried compositions leaving a spray drying tower, which sometimes have temperatures in the neighborhood of 200 to 210 F., under which conditions the fatty acids will react very rapidly, after which it is desirable to agitate and cool the granules to avoid caking and lumping.

The moisture content of commercial granular soap productsis usually controlled within well defined ranges that vary with the type of product and according to the amount and types of builders included therein. I have found that within limits the benefits obtained with my process are increased as the product moisture is increased. Therefore, I prefer to maintain the moisture on the high side of the range, but yet low enough so that the product will not cake or lump during processing and packing operations. Such optimum ,moistures can be about 4% for products low in .builder content, whereaswi'th more highly builtproducts the optimum can be about 20% or even-greater. In fact the process reduces balling tendencies in soap compositions containing as much as 30% moisture. If the untreated granules have been dried below the optimum. moisture level, the reduction in balling tendencies can be improved by applying water or steam to the granules in addition to the fatty acids. I

The wide variations in conditions of temperature, solvent and moisture level can cause the time of reaction to vary considerably. While I prefer to use conditions such that the reaction will be substantially complete within a few minutes so as to facilitate control of the process, it is obvious that under some conditions the reaction will 1 approach completeness very slowly. In such cases some improvement in theproduot may well occur even after the product has been packed.

Not only is the rate of the reaction step affected by operatingconditions but so also is the time at which it starts. Thus-when the fatty acids are applied in the solid state, the start of the reaction step can conceivably be delayed for hours or days. However, seldom are'such delays commercially desirable, and normally it is preferred to apply the fatty acids in liquid form on soap particles having a temperature abovethe melting point of the fatty acids. Under such conditions we'find that the reaction, which follows the application of the initial part of the fatty acids to any one portion of the soap particles, is already'well under way or indeed can be substantially complete by the time that the final part of the fatty acids is applied. Thus the time element of the second step compared to that of the first step can be controlled with regard to both rate and period by-varying the operating conditions, particularly with regard to temperature.

The depth to which the fatty acids penetrate into the surface portion of the soap particles is variable. Obviously, it can vary with the amount of fatty acid used, temperature of soap, silicate content and density of the soap particles. Furthermore, the rate at which it is neutralized will depend in part on the amount of silicate in :the soap and the temperature employed.

The process of this invention can be used for particulate soap products in general that show a tendency to ball. Thus, for example, very marked improvement is obtained with regard to balling in ground products such as ground soap flakes, chips or threads that have balling tendencies.

It is to be understood that the foregoing more particularly described processes are to be considered as illustrative of preferred methods only; such changes and modifications therein are contemplated as would normally occur to those skilled in the art to which the invention relates. 7

Having thus described my invention, what I claim and desire to secure by Letters Patent is: i

1. In the process of reducing the balling tendencies of particulate compositions consisting essentially of sodium soaps containing insufiicient soaps of saturated fatty acids having 8 to 14 carbon atoms to prevent balling of the particles and an amount of sodium silicate solids not less than 1%.% and not greater'than 50% of said composition and uniformly distributedtherein, the steps of applying to the particles from 1% to about 7% of a saturated fatty acidhaving 8 to 14 carbon atoms and reacting said fatty acid in fluid condition-with silicate solids at the surface of said particles.

2.'-The process of claim 1 wherein the soap particles are treated-with from 2 to of the fatty acid.

3. Theprocess of claim 1 wherein the soap particles are treated by spraying the fattyacid on the soap particles, while maintaining the temperature of the particles within a range of from 50-l 15 F, and maintaining the moisture ofthe particles within a range of 4 to 4; The process cf'claim 1 wherein the fatty acid is a mixture of fatty acids derived from an oil of the coconut oil group.

5. The process of claim 4 wherein the fatty acids are themixed fatty acids of coconut oil.

6. The process of claim 4 wherein the-fatty acids are 8. A particulate soap product consisting of an inner portion of a soap composition consisting essentially of sodium soaps containing insufiicient soaps of saturated fatty acids having 8 to 14 carbon atoms to prevent balling and at least l /2% and not more than 50% ofsodium silicate uniformly distributed therein, and a crust portion comprising the reaction products of silicate and applied saturated fatty acid having from 8 to 14 carbon atoms in the molecule, the amount of said fatty acid being equal to from 1% to about 7% of the weight of the soap particle.

9. The product of claim 8 wherein said fatty acid is a mixture of fatty acids derived from'jan oil of the coconut oil group.

10. The product of claim 8 wherein said fatty acid isa mixture of fatty acids derived from coconut oil.

11. The'product of claim 8 whereinsaid fatty acid is a mixture of fatty acids derived .from palm kernel oil.

12. The product of claim 8 whereinthe amount of said fatty acidsis from 2 to 5% of the weight of the soap particle.

' 13. A particulate soap product consisting of an inner ticle, the SiOz/NazO .ratio of the silicate in the crust portion being greater than that'of said inner portion.

14. In the process of reducing balling tendencies in soap particles consisting essentially of sodium soaps containing insuificient soaps of saturated fatty acids having 8 to 14 carbon atoms to prevent balling and at least 1 /2 and not more than about 50% sodium silicate solids uniformly distributed therein, the steps of treating the surface of the soap particles at temperatures of from 50 F. to F. with from 2 to 5% by weightof fatty acids derived from coconut oil, the moisture content of said soap particles being in the range of 4 to 20%; and reacting the fatty acids with the silicate in thesurface of said particles.

15. A particulatesoap product consisting of an inner portion of a soap composition consisting essentially of offatty acids'being equal to from 2 to 5% of the weight of the soap particle.

.16. In the process of reducing balling tendencies .in soap particles containing substantially .1 /2% to 50% sodium silicate solids, the steps of treating the surfaceof the soap particles at temperatures from 50 F. to 115 F.

with froml to about 7% by weight of saturated mixed fatty acids derived from oils ofthe coconut oil group, reacting the fatty acids with the silicate in the surface of said particles and continuing the reaction under bulk storage conditions.

(References on following page) 9 References Cited in the file of this patent 2,423,451 UNITED STATES PATENTS gigggg; 1,989,765 Moss Feb. 5, 1935 2,243,054 Vail May 20, 1941 2,388,632 Byerly Nov. 6, 1945 580,627

10 Holuba July 8, 1947 Miles Dec. 14, 1948 Badman Mar. 29, 1949 FOREIGN PATENTS Great Britain Sept. 13, 1946

Claims (2)

1. IN THE PROCESS OF REDUCING THE BALLING TENDENCIES OF PARTICULATE COMPOSITIONS CONSISTING ESSENTIALLY OF SODIUM SOAPS CONTAINING INSUFFICIENT SOAPS OF SATURATED FATTY ACIDS HAVING 8 TO 14 CARBON ATOMS TO PREVENT BALLING TO THE PARTICLES AND AN AMOUNT OF SODIUM SILICATE SOLIDS NOT LESS THAN 11/2% AND NOT GREATER THAN 50% OF SAID COMPOSITION AND UNIFORMLY DISTRIBUTED THEREIN, THE STEPS OF APPLYING TO THE PARTICLES FROM 1% TO ABOUT 7% OF A SATURATED FATTY ACID HAVING 8 TO 14 CARBON ATOMS AND REAT THE SURFACE OF SAID PARTICLES.

13. A PARTICULATE SOAP PRODUCT CONSISTING OF AN INNER PORTION OF A SOAP COMPOSITION CONSISTING ESSENTIALLY OF SODIUM SOAPS CONTAINING INSUFFICIENT SOAPS OF SATURATED FATTY ACIDS HAVING 8 TO 14 CARBON ATOMS TO PREVENT BALLING AND AT LEAST 11/2% AND NOT MORE THAN 50% OF SODIUM SILICATE UNIFORMLY DISTRIBUTED THEREIN, AND A CRUST PORTION COMPRISING THE REACTION PRODUCTS OF SILICATE AND SATURATED FATTY ACIDS HAVING FROM 8 TO 14 CARBON ATOMS IN THE MOLECULE, THE AMOUNT OF SAID FATTY ACID BEING EQUAL TO FROM 1% TO ABOUT 7% OF THE WEIGHT OF THE SOAP PARTICLE, THE SIO2/NA2O RATIO OF THE SILICATE IN THE CRUST PORTION BEING GREATER THAN THAT OF SAID INNER PORTION.