US2371623A - Method of preserving soap and resulting product - Google Patents

Description

pounds are used.

Patented 20, 1 945 METHOD OF PRESERVING SOAP AND RESULTING PRODUCT Lloyd F. Henderson, Reading, Mass., asslgnor to Lever Brothers Company, a corporation of Maine No. Drawing. Application February 6, 1943,

Serial N0. 475,001

14.01am. (Cl. zoo-398.5)

The present invention relates to detergent compositions derived from higher fatty materials and, more particularly, to soap and non-soap products comprising one or more ingredients which are Itis an advantage of this invention that the stabilizing substances which it i proposed to incorporate in the detergent do not have the property of imparting undesirable odor or of causing discoloration of the detergent as is frequently the case when stabilizers, for example, phenolic compounds are utilized for stabilizing purposes. Moreover, the group of stabilizing substances used in accordance with the present invention are water soluble and do not form precipitate as is sometimes the case when certain metallic com- Furthermore, the present stabilizing substances may be utilized in comparatively small amounts based on the weight of the detergent whereby the amount of detergent in the product is not appreciably decreased, the physical characteristics of the detergent, for example, with respect to hardness, are not adversely affected, and the cost of stabilizing the detergent is kept at a minimum.

By higher fatty detergent I refer to soaps and non-soaps having an aliphatic radical of 8 or more carbon atoms. The soaps are the alkali metal, ammonium, alkyl, amine and alkylolamine salts or esters of higher fatty acids such as may be prepared, for example, by saponifyinan animal or vegetable fat with an alkali metal compound. The higher fatty non-soap detergents are sulfonated or sulfated compounds such as higher alkyl sulfonates or sulfates, taurides, and other compounds derived fromhigher fatty materials which group is well known in the art as having detergent properties. All compositions of this type, regardless of the source of the ingredients or the technique of manufacture, may be stabilized in accordance with the present invention and all such compositions are intended to be within the scope of the invention. For convenience only. I

will describe my invention hereinafter as applied to soap. p 1

It is well known that soaps of the character described turn'ran cid as a result of oxidation or otherwise. In the case of white soap there is usually a noticeable discoloration. It is an object of this invention to inhibit or retard this tendency to develop ra'ncidity without at the same time incorporating large amounts of non-soap materials into the soap and without causing undesirable collateral effects such as the development of undesirable color and odor, and softness.

The susceptibility to the development of rancidity which is characteristic of conventional soaps may be inhibited or retarded in accordance with this invention by incorporating one or more of the group of stabilizing substances herein disclosed, in the soap at any convenient stage of the soap making process. Preferably, the stabilizing substances are added to the soap subsequent to its boiling, for example, during crutching or milling, or both. The exact time at which the stabilizing substances are added or the method by which they are added to the soap is not critical, and by the necessary to use only relatlvelysmall amounts ofthe stabilizing substances inorder to effect aqebased on the weights of the soap and, in general,

less than 0.5% of stabilizer in the soap product is a desirable for adequate stabilization. There is no apparent advantage in utilizing greater amounts of the stabilizer, and, therefore, it is preferred to utilize amounts within the above range, although amounts up to not more than about 5% of stabllizer, based on the weight of the soap, may be employed.

The group of stabilizing substances which may be used in accordance with the invention are any of the aliphatic or aromatic compounds containing one or more trivalent nitrogens and two or more carboxyl groups connected to at least one of the nitrogens through a short aliphatic chain having not more than four carbon atoms and preferablythrough the methylene group. Such compounds would contain the essential group:

nooo-x HO O C-X where X is the above referred to short'aliphatic chain, such as CH2-. The following general formulas are illustrative of the type of compounds above defined:

x--ooon x-ooon N x-ooon x-coon 7 in which x is a short aliphatic or substituted aliphatic chain; 7X is a hydrogen, alkyl, cycloalkyl, aryl, or substituted alkyl, cycloalkyl or aryl group, or a carboxyl alkyl group containing not more than 4 carbon atoms in the chain portion of the molecule; Y is an aliphatic or substituted aliphatic chain, or an aromatic or cycloaliphatic nucleus. The carboxylates, including the salts of the above acids, such as alkali metal, ammonium, and amin salts, and the esters of the acids, such as the methyl and ethyl esters, as well as the anhydrides of the acids, are equally effective and are included within the above definition. When a carboxylate is used as the stabilizer the positive radical of the carboxylate preferably may be theisame as the positive radicalof the detergent. .Thus, an ammonium salt of one of the above acids would be used with an ammonium soap.

Among. the compositions of this type which may be used in accordance with this invention are the alkali metal salts of, for example, the following:

Nitrilotrlacetic acid Alkylene diamino tetracetic acid C-alkyl-nitriiotriacetic acid C-dialkyl nitrilotriacetic acid C-phenyl-nitriloiriacetic acid 'C-phenyI alkyl-nitrilotriacetic acid C-cyclohexenyl-nitrilotriacetic acid The above list of compounds is given merely by way of illustration and is not intended to be understood as limitativeof the scope of the invention.

The nitrilodiacetic acid radical referred to in the specification and the claims has the following formula:

CHzCOOH orncoon Nitrilotriacetic acid as the formula:

CHZCOOH N-crncoon cmooon soap. Samples of the resultingsoap and addltional samples thereof prepared by adding small quantities of the stabilizing compounds during example, were carried out with a substantially neutral kettle soap prepared by saponifying substantially '70 parts tallow and 25 parts coconut oil with 'suflicient caustic soda to make a neutral plodded and formed into cakes.

crutching were then permitted to stand at room conditions and also under controlled conditions of elevated temperature and high-humidity. At

theend of each day the soap was examined and any odor indicative of rancidity was noted. The following table (Table I) of the results obtained with specific samples is given merely by way of illustration and'is not to be understood as limiting the scope of the invention.

Table I D tic (test i d Stabilizing compound stabilizing V m n o r 0 compound 115 F. R.%.

Per cent 7 N itrllotrlaoetic acid 0. 2 Rancid after 79 days. Ethigene diamlno tetracetic 0. 2 Good after 24! days.

ac Blank .1 None. Rancid after 3 days.

' tests directed to a milled type of soap. In carrying out these additional tests, soap chips of reduced moisture content were prepared in a conventional manner utilizing the-kettle soap stock referred to above. Sampleamounts of the dried chips were then milled alone and with a small amount of a stabilizing compound added during the milling, following which the soap was The soap was then tested for stability against the development a of rancidity as describedabove. The following table (Table II) of the results obtained with specific samples which is given merely as illustrative, indicates that even superior results were obtained in the case of a milled soap as compared with a framed type of soap.

- Table II Amotunt Duration of test period Stabilizing com- Magi? pound ing comll5F. F. gg gi pound 80% R. H. 60% R. H. mm

Percem a Nitrllotriaoetic mi. 0.2 Rancid46 Good 202 Good 202 days. da s. days. Ethylene diamino 0. 2 Good 224 Goo 224 Good 224 tetracetic acid. days. days. days. Blank None Rancid 3 Rancid l3 Rancid ys d ysay In view of the above data (TablesI and m, it

is apparent that stabilizing compoundsfselected from the group herein disclosed possess marked stabilizing properties when incorporated in soap. Similar test results may be obtained by the use of compounds selected from the group herein disclosed other than those whose test results have been'specifically set forth in the tables above for illustrative purposes and the use of all such compounds in a soap composition'is intended to be within the scope of the present invention.'

least one of the nitrogens through a methylene I claim:

1. A detergent selected from the group consisting of soap and higher fatty non-soap detergents having a normal tendency to become rancid and being rendered resistant to the development of rancidity by having incorporated therein a small amount of a non-detergent compound selected group, and their salts, esters and anhydrides.

8. A method of retarding the development of ing at least one nitrilodiacetic acid radical.

from the group consisting of aliphatic and aromatic compounds containing at least one invalent nitrogen and at least two carboxyl groups connected to at least one of the nitrogens through a short aliphatic chain having not more than {our carbon atoms, and their salts, esters and anhydrides.

2. A detergent selected from the group consisting of soap and higher fatty non-soap detergents having a normal tendency to become rancid and being rendered resistant to the development of rancidity by having incorporated therein a small amount of the order of about 0.01 to 1.0%, based on the weight of the detergent, of a non-detergent compound selected from the group consisting of aliphatic and aromatic compounds containing at least one trivalent nitrogen and at least two carboxyl groups connected to at least one of the nitrogens through a methylene group, and their salts, esters and anhydrides.

3. A soap rendered resistant to the development of rancidity having incorporated therein not more than 5% of an alkali metal salt of an organic aminocarboxylic acid containing at least one nitrilodiacetic acid radical.

4. A soap rendered resistant to the development of rancidity having incorporated therein a small amount of the order of about 0.01 to 1.0% of an alkali metal salt of nitrilotriacetic' acid.

, 5. A soap rendered resistant to the develop-.

ency to become rancid and being resistant to the ment of rancidity having incorporated thereima small'amount of the order of about 0.01 to 1.0% 0! an alkali metal salt of ethylene diamino tetracetic acid. v

6. A- method of retarding the development of rancidity or a detergent selected from the group consisting of soap and higher fatty non-soap detergents having a normal tendency. to become rancid, comprising. incorporating "in said detergent a small amount of a non-detergent compound selected from the group consisting of aliphatic and aromatic compounds containing at least one trivalent nitrogen and at least two'carboxyl groups connected to at least one of the nitrogens through a short aliphatic chain having not more than four carbon atoms, and their salts, estersand anhydrides,

'I. A method oi retardingthe development 'of rancidity of a detergent selected from, the group consisting of soap and higher fatty non-soap detergents having a normal tendency to become rancid, comprising incorporating insaid detera non-detergent compound selected from the.

group consisting of aliphatic and aromatic compounds containing at least one trivalent nitrogen and at least two carboxyl groups connected to at -9 A method of retarding thedevelopment of rancidity of a soap comprising incorporating in the-soap a small amount of the order'of about 0.01 to 1.0% of an alkali metal salt of nitrilotriacetic acid.

10. A method ofretarding the development of rancidity of a soap comprising incorporating in the soap a small amount of the order of about 0.01 to 1.0%- of an alkali metal salt of ethylene diamino tetracetic acid. V i

11. An alkali metal soap having a normal tenddevelopment of rancidity by having incorporated therein not more than 5% of a non-detergent compound selected from the group consisting of aliphatic and-aromatic compounds containing at least one trivalent nitrogen and at least two carboxyl groups connected to at least one of the the soap, of a non-detergent compound selected from the group consisting of aliphatic andaromatic compounds containing at least one tri- I valent nitrogen and at least ,two carboxyl groups connected to at least one of the nitrogensthrough a methylene group, and their salts, esters and anhydrides. I

13. A method of retarding the development of rancidity in alkali metal soaps having a-normal tendency to become rancid, which comprises 111- non-detergent compound selected from the group consisting of aliphatic and aromatic compounds containing at least one trivalent nitrogen and at 1 least two carbonyl groups connected to at least 0 one of the nitrogens through a short aliphatic "chain having not more than four carbon'atoms, and their salts, esters and anhydrides.

14. A method of retarding the development of rancidity in alkali metal soaps having a normal tendency to become rancid, which comprises incorporating in the soap a small amountof the order of about 0.01% to 1.0%, based on the tveight of the soap, oi anon-detergent compound selected from the group consisting of aliphatic and aromatic compounds containing at least one tri- Q, valent nitrogen and at least two carbonyl groups connected to at least one oi. the nitrogens through a methylene group, and their salts, esters and anhydrides. r

LLOYD F. HENDERSON.

corporating in the soap not more than 5% of a Patent no. 2, 71,62

CERTIFICATE OF CORRECTION.

. r 20, 1.915- LLOYD F. HENDERSON.

It is hereby certified that error appears in the printed specification 7 of the above numbered patent requiring correction as follows: Page 1, first column, line 7, for "the" read -this--; page 2, first coluinn, line .57,

for "acid as" read --acid hasline Tip, for "'70 parts" read -75 parts--;

and second column, line 20, Table 1, third colnnin 55601"; for the indistinct numeral before "days read --2L|.7 and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 5th dayof June, A. D5 1915.

Leslie Frazer (Seal). Acting Commissioner of Patents.