US2303212A - Soap composition - Google Patents

Description

Patented Nov. 24, 1942 FFICE I 2,303,212 SOAP COMPOSITION Mearl A. Kise and James F. Vitcha, Syracuse, N. Y., assignors to The Solvay Process Company, New York, N. Y., a corporation of New York a No Drawing. Application May 2c, 1939,

"Serial No. 275,795

14. Claims.

The present invention relates to soap compositions adapted for general detergent use in water of any degree of hardness.

The soap compositions of the invention are composed of a proportion of one or more ordinary soaps; yet they are adapted for use in hard water in which an ordinary soap is unsatisfactory due to the formation of objectionable curds and the necessity for the use of an excessive quantity of soap. While there have been developed a wide variety of synthetic detergents intended to replace soaps in many of the processes in which these compounds are used, ordinary soaps remain the most widely used washing agents. This is because they are relatively inexpensive and have a number of desirable properties which as yet have not been duplicated in the more costly synthetic detergents. Thus ordinary soaps of good quality are efficient washing agents for most materials in soft water. Hence where softwater is available they are generally satisfactory.- Further, soaps have softening properties which improve the feel of textile materials that have been washed with their aid.

In regions where only hard water is available, however, the advantages of soaps are'more than counterbalanced bytheir disadvantages. If soap alone is used for washing in hard water at least a portion of the soap is converted into a calcium soap which precipitates in the form of sticky curds. These curds not only have no cleansing properties but constitute impurities that must be dispersed by a part of the unconverted soap which is then not available for cleansing. Thus, for effective washing in hard water, a relatively large quantity of soap is required and the economic advantage of this washing agent is largely reduced. If the usual alkaline water softeners are used with soap, an additional item of cost is introduced without materially increasing the cleansing efficiency of the resulting solution since, while these Water softeners act to dissolve grease, they are not good washing agents for most purposes. Also, a clean'singsolution containing such water softeners is strongly alkaline and thereforehas-an undesirable effect upon the hands of the user and upon delicate fabrics. Anotherdisadvantage noticed in connection with the use of alkaline water softeners is. the fact that their softening action does not extend to the rinsing operation. When a textile material that has been washed in a hard water solution of a soap and an alkaline water softener is rinsed with hard water,

in the material to form insoluble soaps that are diflicult to remove.

It has been proposed to overcome the disadvantages of soaps by mixing them with certain synthetic detergents or dispersing agents which are hard water resistant; that is detergents or dispersing agents that do not form insoluble calcium salts. Tests have shown that these proposals are not entirely satisfactory. While solutions of the mixtures in hard water are free from curds due to the dispersing action of the detergent or dispersing agent, in many cases the cleansing properties of the solutions are not sufficieritlysuperior to those of soap alone to justify the added cost of the detergent or dispensing agent. Also, it isordinarily necessaryto use so great a quantity of the detergent or dispersing agent that the cost of the combined agent approaches that of the detergent or dispersing agent alone.

It is an object of the present invention to provide relatively inexpensive soap compositions which are etlectivewashing agents when used in hard water. A further object of the invention is to provide soap compositions which have the desirable softening properties of soaps and which may be used in hard water without displaying objectionable curd formation. Another object of the invention is to provide soap compositions which may be used effectively for .the washing of cotton and woolen materials in hard water and which leave these materials with a soft feel.

Other objects of the invention will in part be obviousand will in part appear hereinafter.

It has been discovered in accordance with the present invention that by mixing an ordinary soap, such as an alkali metal salt of a higher fatty acid, with an alkali metal, ammonium,- or organic amine salt of an ester of an alpha sulfonic acid derivative of a higher fatty acid containing from 12 to 22, preferably 16 to 18, carbon atoms and a monoor 'dihydric alcohol containing not more than three carbon-atoms, an eflicient soap composition is obtained which is materially suthe calcium salts in the water react with the so p perior to an ordinary soap for cleansing in hard water. As a feature of the invention it has been found that the advantages flowing from the-combination of a soap with one or more of the abovedefined sulfo fatty acid ester salts can be obtained with the use of a relatively small amount of an ester salt or salts. This makes it possible to prepare compositions composed of a major pro portion of an ordinary soap which are nevertheless adapted for efficient use in hard water; Such compositions are relatively inexpensive and pos r sulting ester or mixtures of esters. The invention is not restricted to the use of ester salts prepared in this way, however, and it will be understood that in speaking of an ester of an alpha sulfonic acid derivative of a saturated fatty acid and an alcohol it is not meant necessarily that the ester has been prepared by an esterification method using the alcohol, but simply that the esterifying radical of the ester corresponds to the residue remaining after removalof a hydroxyl group of the alcohol, regardless of the method of preparation of the ester.

The alpha sulfonic acid derivatives of saturated fatty acids referred to above may be derivatives of any one or a mixture of the saturated fatty acids containing 12 to 22 carbon atoms, including saturated fatty acids which contain substituents that do not affect adversely the detergent and dispersing properties of the ester salts. In this connection it is pointed out that salts of esters of alpha sulfonic acid derivatives of saturated fatty acids which contain hydroxyl groups as substituents of the alpha or beta carbon atoms have substantially the same detergent and dispersing properties as the salts of esters of derivatives of the correspondingunsubstituted acids. Examples of suitable fatty acids are stearic acid, palmitic acid, myristic acid, arachidic acid, behenic acid, and penta-, hepta-, and nonadecanoic acids.

The alcohols from which the ester salts used in the compositions of the invention are derivable may be any straight or branched chain, monoor dihydric alcohols containing not more than three carbon atoms such as, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, normal propyl alcohol, ethylene glycol, and 1,2- and 1,3.- propandiol. The ester salts may be alkali metal (e. g., sodium or potassium), ammonium-or organic amine salts, such as ethanolamine, diethanolamine, triethanolamine, and tetramethyl-ammonium hydroxide salts of the esters. Specific examples of sulfo fatty acid ester salts suitable for use in the compositions of the invention are the following: sodium methyl alpha sulfo stearate. potassium methyl alpha sulfo stearate, sodium ethyl alpha sulfo stearate, potassium ethyl alpha sulfo stearate. sodium isopropyl alpha sulfo stearate. sodium methyl alpha sulfo palmitate, sodium ethyl alpha sulfo palmitate. potassium methyl alpha sulfo arachidate,

sodium methyl alpha sulfo hepfadecanoate, tetramethyl ammonium methyl alpha sulfo stearate, diethanol ammonium methyl alpha sulfo stearate, sodium isopronyl alpha sulfo palmit-ate, sodium n-propyl alpha sulfo stearate. sodium isopropyl alpha sulfo myristate, and potassium glycol alpha sulfo behenate. The esterifying radicals of the ester salts, similarly to the acyl radicals thereof, may contain substituents that do not affect adversely the detergent and disersing properties of the ester salts. Because saturated fatty acids ordinarily are most easily .the invention as mixtures rather than as single compounds.

Of the ester salts adapted for use in the compositions of the invention, the most valuable are the sodium and potassium salts of the methyl. ethyl, and isopropyl esters of the alpha sulfonic acid derivatives of palmitic, heptadecanoic, and stearic acids. For example, particularly important ester salts have been found to be the sodium or potassium salts of the methyl ester of the alpha sulfonic acid derivative of technical stearic acid. Technical stearic acid varies in composition but always contains an appreciable proportion (e. g., 30 per cent) of palmitic acid.

In preparing the compositions of the invention, the proportions in which the soap and the one or more sulfo fatty acid ester salts are combined may be varied within relatively wide limits. Inasmuch as soap alone is an effective washing agent in soft water, the amount of sulfo fatty acid ester salt required or preferred in a given composition is largely dependent upon the hardness of the water in which the composition is to. be used. By'mixing as little as 2 parts by weight of sulfo fatty acid ester salt with 98 parts by weight of soap a composition is produced which can be used in moderately hard water without the production of curds, but which is not markedly superior in its washing action to soap alone. However, in order to produce a composition which is noticeably superior in its washing action to soap alone, it is preferred to use at least 5 parts by weight of one or more of the sulfo fatty acid ester salts for each 95 parts by weight of soap included in the composition. On the other-hand, even if the compositions are to be employed in extremely hard water, it has been found to be unnecessary to use a greater proportion of ester salt than that corresponding to equal parts by weight of ester salt and soap. For washing in water of moderate hardness (i. e., water of a hardness corresponding to 200 P. P. M. of CaCOa or below) a composition containing 10 parts by weight of one or more of the sulfo fatty acid ester salts and 90 parts of soap is generally satisfactory. When exceedingly hard waters are to be 'used the amount of ester salt is preferably increased correspondingly. For example, for general washing purposes in water of 400 P. P. M. hardness, compositions containing 20 parts by weight of one or more of the ester salts for each 80 parts of soap are ordinarily entirely satisfactory. In some cases, however, it is advantageous to use in water of this hardness a composition in which the ester salt and soap are in the proportions of 30 parts by weight of the ester salt for each 70 parts of soap.

In addition to the sulfo fatty acid ester salts and soap, the compositions of the invention may contain, if desired, a proportion of an inorganic salt whichdoes not affect adversely the desirable properties of the compositions. In this connection it is pointed out that strongly alkaline salts (i. e., salts which would impart to aqueous solutions of the compositions pH. values above 10) should preferablynot be included in the compositions because such salts are not only deleterious to the hands of the user and many materials washed therewith but also tend to cause hydrolysis of the ester salts. On the other hand it is undesirable to incorporate in the compositions an inorganic salt which would reduce the alone.

sitions' below the effective washing range for soap used are tetra sodium pyrophosphate, sodium sesquioarbohate, sodium silicate, sodium tetraborate, and sodium or potassium sulfate. Other additions, luch as perfumes, dyes, antiseptics (e. g., phenol), and bleaching agents (e. g., perborate), which are frequently included in soap compositions, may also 'be incorporated in the compositions of the invention.

As already stated, the compositions of the invention are effective washing agents in hard water. Thus they may be used effectively for the washing in hard water of textile materials of various kinds; such as, for example, cotton, wool, and artificial silk materials. The solutions of the compositions in hard water are free from curds and possess pronounced cleansing properties. A textile material washed in a solution of a composition of the invention in hard water may be rinsed easily even with hard water withoutthe formation therein of insoluble calcium soaps. The aqueous solutions of the composi-.

tions are substantially neutral and do not produce the objectionable results on the human sk n or fabrics, particularly fabrics composed of animal fibers, noticed in the use of detergent compositions which are strongly alkaline in character. The compositions are particularly valua'ble for use in washing ceramic ware (e. g., glass) in hard water since they accomplish such washing without depositing a -fi1m ofcalcium salts.

In order that the invention maybe morev fully understood reference should be had to the following speciflc examples in which are disclosed typical compositions included within the scope of the invention. The parts are by weight.

Example 1.-90 parts of a typical soap consisting of a commercial mixture of sodium salts of higher fatty acids with neutral equivalent of about 255 (e. g., Ivory soap) are mixed with parts of the sodium salt of the methyl ester of the alpha sulfonic acid derivative of stearic acid. The mixture may be effected by melting the soap, adding the ester salt, and permitting the mass to cool in cake form. The composition prepared in this way is a valuable washing agent for use in moderately hard water; i. e., in water of 200 P. P. M. CaCO: hardness or below. -Thus, if used in the proportions of 2.5 grams per liter in water of this hardness, it washes soiled cotton cloth at least as eflloiently as soap alone in soft water. Soap alone in water of this hardness, if used in the proportions of 2.5 grams per liter, is not a satisfactory washing agent. Further, the solution of the above composition in the hard water is free from curds whereas the soap solution is contaminated with curds. If used for washing wool in water of this hardness in the proportions of 2.5 grams per liter, the above composition isa satisfactory cleansing agent whereas soap alone in the same proportions produces substantially no cleansing effect.

Example 2.--80 parts of the soap used in Exampie 1 are mixed with 20 parts of the sodium salt of the methyl ester of the alpha sulfonic acid derivative'of stearic acid. The composition thus formed has properties similar to the composition of Example I but may be used effectively for the washing of cotton and wool in harder water, even though used in the same proportions.

Among the inorganic salts that can be r The specific soap and sulfo fatty acid ester salt employed in the compositions described in the above examples may be replaced with substantially equivalent results by other soaps and others of the class of sulfo fatty acid ester salts described above. For example, in place of the soap used there may be employed any other soft or hard soap, and in place of the sulfo stearic acid methyl ester salt there may be employed any one or a mixture of the sulfo fatty acid ester I salts specifically mentioned above. Further, the proportions of the soap and the alkyl ester salt used in the compositions may be varied in the manner previously described, the preferred proportions to be employed being dependent largely upon the hardness of the water in which the compositions are'to be used. In this connection it will be understood that while an excess of an alkyl ester salt in the compositions is not undesirable from a functional standpoint, the use of a large excess adds to the cost because the alkyl ester salts are more expensive than ordinary soaps. As previously indicated, a single allwl ester salt or a mixture of such salts may be used in the compositions. In the appended claims where a salt of an ester of a sulfonic acid derivative of a saturated fatty acid is referred to, it is intended to include a mixture of such salts as well as. a single salt.

To the compositions disclosed in the examples there may be added the inorganic salts and/or other materials referred to above, which are fre-' quen'tly included in soap compositions. In compositions containing such additional materials, the ratio between the soap and the sulfo fatty acid ester salt should preferably be the same as that in compositions in which such additional materials have not been included.

Since certain changes may be made in the compositions described above, it is intended that,

all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A soap composition adapted for use in hard water comprising a water-soluble soap and a salt selected from the group consisting of alkali metal, ammonium, and organic amine salts of an ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 12 to 22 carbon atoms, the esterifying radical of said ester corresponding to the residue remaining after the removal of a hydroxyl group from an alcohol containing not more than three carbon atoms and not more than two hydroxyl groups, said soap and said salt being present in the composition in ratios varying from 98 parts by weight of -said soap and 2 parts by weight of said salt to 50 parts by weight of said soap and 50 parts by weight of said salt.

. 2. A soap composition adapted for use in hard water comprising a water-soluble soap and a salt selected from the group consisting 'of alkali metal,

ammonium, and organic amine saltsof an ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 12 to 22 carbon atoms, the esterifying radical of said ester corresponding to the residue remaining after the removal of a hydroxyl group from an alcohol containing not more than three carbon atoms and not more than two hydroxyl groups, said soap and said saltbeing present in the composition in ratios varying from parts by weightof said soap and 5 parts by weight of said salt to 50 parts by weight of said soap and 50 parts by Weight of said salt.

3. A soap composition adapted for use in hard water comprising a water-soluble soap and an alkali metal salt of an ester of an alpha sulfonic by weight of said soap and 5 parts by weight of said alkali metal salt to 50 parts 'by weight of said soap and 50 parts by weight of said alkali metal salt. 1

4. A soap composition adapted for use in hard water comprising a water-soluble soap and an alkali metal salt of an ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 12 to 22 carbon atoms, the esterifying radical of said ester corresponding to the residue remaining after the removal of a hydroxyl group from an alcohol containing not more than three carbon atoms and not more than two hydroxyl groups, said soap and said alkali metal salt being present in the composition in ratios varying from 90 parts by weight of said soap and parts by weight of said alkali metal salt to '70 parts by weight of said soap and 30 parts by weight of said alkali metal salt.

5. A soap composition adapted for use in hard water comprising an alkali metal soap and an alkali metal salt of an ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 16 to 18 carbon atoms, the esterifying radical of said ester corresponding to the residue remaining after the removal of a hydroxyl group from an alcohol containing not more than three carbon atoms and not more than two hydroxyl groups, said soap and said alkali metal salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said alkali metal salt to '70 parts by weight of said soap and 30 parts by weight of said alkali metal salt.

6. A soap composition adapted for use in hard water comprising a sodium soap and the sodium salt of an ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 16 to 18 carbon atoms, the esterifying radical of said ester corresponding to the residue remaining after the removal of a hydroxyl group from an alcohol containing not more than three carbon atoms and not more than two hydroxyl groups, said soap and said sodium salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said sodium salt to 70 parts by weight of said soap and 30 parts by weight of said sodium salt.

. 7. A soap composition adapted for use in hard water comprising a water-soluble soap and an alkali metal salt of the methyl ester of an alpha sulionic acid derivative of a saturated fatty acid containing 16 to 18 carbon atoms, said soap and said alkali metal salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said alkali metal salt to 70 parts by weight of said soapand 30 parts by weight of said alkalimetal salt.

8. A soap composition adapted for use in hard water comprising a water-soluble soap and the sodium salt of the methyl ester of the alpha sulfonic acid derivative of stearic acid, said soap and said sodium salt being present in the composition in ratios varying from 95 parts by weight of said soap and 5 parts by weight of said sodium salt to 50 parts by weight of said soap and 50 parts by weight of said sodium salt.

7 9. A soap composition adapted for use in hard water comprising a water-soluble soap and the sodium salt of the methyl ester of the alpha sulfonic acid derivative of stearic acid, said soap and said sodium salt being present in the composition in ratios varying from parts by weight of said soap and 10 parts by weight of said sodium salt to '70 parts by weight of said soap and 30 parts by weight of said sodium salt.

10. A soap composition adapted for use in hard water comprising a water-soluble soap and the alkali metal salt of the ethyl ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 16 to 18 carbon atoms, said soap and said alkalimetal salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said alkali metal salt to '70 parts by weight of said soap and 30 parts by weight of said alkali metal salt.

11. A soap composition adapted for use in hard water comprising a water-soluble soap and the sodium salt of the ethyl ester of the alpha sulfonic acid derivative of stearic acid, said soap and said sodium salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said sodium salt to '70 parts by weight of said soap and 30 parts by weight of said sodium salt.

12. A soap composition adapted for use in hard water comprising a water-soluble soap and the alkali metal salt of the isopropyl ester of an alpha sulfonic acid derivative of a saturated fatty acid containing 16 to 18 carbon atoms, said soap and said alkali metal salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said alkali metalsalt to '70 parts by weight of said soap and 30 parts by weight of said alkali metal salt.

13. A soap composition adapted for use in hard water comprising a water-soluble soap and the sodium salt of the isopropyl ester of the alpha sulfonic acid derivative of stearic acid, said soap and said sodium salt being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said sodium salt to '70 parts by weight of said soap and 30 parts by weight of said sodium salt.

14. A soap composition adapted for use in hard water comprising an alkali metal soap and the alkali metal salts of the methyl esters of the alpha sulfonic acid derivatives of a mixture containing stearic and palmitic acids, said soap and said alkali metal salts being present in the composition in ratios varying from 90 parts by weight of said soap and 10 parts by weight of said alkali metal salts to '10 parts by weight of said soap and 30 parts by weight of said alkali metal salts.

M'EARL A. KISE. JAMES F. VITCHA.