US3663459A - Detergent bar - Google Patents

Abstract

THE WATER SOLUBLE SALTS OF N-ACYL-GLUTAMIC ACIDS AND NACYLASPARTIC ACIDS WHOSE ACYL GROUPS ARE THE ACYL RADICALS OF SATURATED OR UNSATURATED FATTY ACIDS HAVING 8 TO 22 CARBON ATOMS WITH THE ALKALI METALS, AMMONIUM, BASIC AMINO ACIDS, AND OTHER AMINES CAN BE MILLED WITH WATER AND MOLDED INTO BARS BY PROCEDURES CONVENTIONAL IN THE MAKINGING OF MILLED TOILET SOAPS, AND HAVE DESIRABLE PROPERTIES AS DETERGENTS FOR TOILET USE.

Description

United States Patent US. Cl. 252-546 3 Claims ABSTRACT OF THE DISCLOSURE The water soluble salts of N-acyl-glutamic acids and N- acylaspartic acids whose acyl groups are the acyl radicals of saturated or unsaturated fatty acids having 8 to 22 carbon atoms with the alkali metals, ammonium, basic amino acids, and other amines can be milled with water and molded into bars by procedures conventional in the making of milled toilet soaps, and have desirable properties as detergents for toilet use.

The present invention relates to detergents, and particularly to a detergent bar for toilet use.

Ordinary soap usually irritates the skin because of a free alkali content, the rise of pH by hydrolysis, and the presence of lower fatty acid added to improve solubility, foaming power, and detergency. When the ordinary bar soap is used in hard water, insoluble lime soap is formed. Therefore, it is necessary for toilet purposes to replace a part of the soap by other surface active agents and to add skin protecting agents.

Toilet soap, though its free alkali content is low enough not to cause irritation of the skin, still has an undesirable degreasing and drying effect on the skin so that it is necessary to add wetting agents or cream base. These additives reduce detergency.

Although synthetic detegent bars have excellent detergency, they usually require fatting agents and other additives to give them desirable characteristics for toilet use.

Moreover, the synthetic detergent bar has inferior touch to the skin and inferior performance as compared with ordinary bar soap.

It is an object of this invention to provide a detergent bar having satisfactory characteristics for toilet use. More specifically, the invention aims at providing a detergent bar which has good hardness and such solubility that it does not readily disintegrate when immersed in water at 40 C., good foaming power and detergency in soft and hard Water, a gentle effect on the skin, and a comfortable touch during use, and which leaves the skin soft and smooth.

The detergent bars of the invention are prepared by molding mono-salts of N-acyl derivatives of acidic amino acids having an acyl group of 8 to 22 carbon atoms together with an amount of water sufficient to make a shaperetaining body.

Certain N-acylamino acids or their salts have been known to have surface activity and antibacterial effects, and sodium N-aluroyl-sarcosinate has been used therefore in detergents, and such cosmetics as toothpaste. The salts of N-acylamino acids have also been used in heavy duty detergents as minor additives to improve performance. They have never been used as the principal components of a shaped, solid detergent body.

It has now been found that only the salts of N-acyl derivatives of acidic amino acids having acyl groups of 8 to 22 carbon atoms among all salts of N-acylamino acids have the property of forming detergent bodies of desirable characteristics when milled with suitable amounts of water and molded.

The acidic amino acids whose N-acyl derivative salts are the detergent materials of this invention are glutamic acid and aspartic acid. The acyl groups are those of saturated or unsaturated fatty acids having 8 to 22 carbon atoms, such as lauroyl, decanoyl, myristyl, pentadecanoyl, palmityl, margaryl, stearyl, oleyl, and radicals of naturally occurring mixed fatty acids derived from coconut oil, tallow oil, hydrogenated tallow oil, olive oil, soybeans, and corn.

The amino acid component may be in the optically active form or the racemic form. Suitable salts are the alkali metal salts such as those of sodium and potassium, the ammonium salts, salts of basic amino acids such as lysine, ornithine, or arginine, and other water-soluble amine salts. The N-acylamino acid salts may be used as the active detergent material singly or combined, and adjuvant materials such as thickeners, perfumes, pigments, dyes, and the like may be added. Examples of such adjuvants are higher fatty acid amides, salts of N-acyl derivatives of neutral amino acids, alkylene oxide condensates, alcohol, glycerol, and glycerides.

The detergent bars of the invention are prepared by milling the salts of the N-acylamino acids with or without the adjuvants and with a suitable amount of water, extruding the milled material into a bar, and molding the extruded material in a conventional manner.

A dry salt of the N-acylamino acid is first mixed with a suitable amount of water and other additives. The water facilitates milling and makes the detergent moldable so that the bar does not disintegrate in water. Although the proportion of water may be varied depending on the salt and the adjuvants used, it is usually less than 40%, and preferably 3 to 20% of the weight of the solid materials in the composition.

A small rolling mill having three stainless steel rollers of 12 cm. diameter and rotating at 16, 32 and 64 r.p.m. respectively may be used. The mixture is passed through the mill 2 to 10 times. It is then extruded into a bar from an extruder having a heated jacket, and the bar is molded in a press.

The shaped detergent composition so obtained has a solubility value, as determined by a rubbing test, equal to that of toilet soap meeting the Japanese Industrial Standards K-3301, and thus dissolves only moderately in water during use. It has good shape-retaining properties and a soft touch after use like that of toilet soap. It has a pH of 5-7 during use, and this is near the isoelectric point of protein in the surface of the human skin. The composition is stable in hard water, mild to the skin, and makes the skin soft and smooth after use. It has antibacterial elfects and disinfects the skin.

The following examples are further illustrative of this invention. All parts referred to are by weight.

EXAMPLE 1 parts monosodium N-acyl-DL-glutamate, whose acyl groups were those of coconut oil fatty acid, and 5 parts water were milled on a small rolling mill and then extruded into a bar from a small plodder whose nozzle temperature was kept at 55 C. The bar was shaped on a press.

The solubility value of the product according to the rubbing test of the Japanese Industrial Standards K4304- 1956 was 55 (40 C., 10 minutes). It had good foaming power and detergency, caused almost no skin irritation, and left the skin soft and smooth feeling.

EXAMPLE 2 A mixture of 70 parts monosodium N-lauroyl-D-glutamate, 5 parts of the triethanolamine salt of Nlauroyl- L-glutamic acid, and 3 parts water was milled, extruded at a nozzle temperature of 60 C. from a small plodder, and formed into shaped pieces on a press.

The solubility value of this product in the afore-described test was 67. It retained its original shape, did not disintegrate when immersed in water at 40 C., and showed good foaming power and detergency.

EXAMPLE 3 A mixture of 50 parts monosodium N-lauroyl-L-glutamate, 50 parts of the L-lysine salt of N-lauroyLL-glutamic acid, and 10 parts water was milled and further processed as in Example 1.

The solubility value of the product was 65. It did not disintegrate when immersed in water at 40 C. and showed good detergency.

EXAMPLE 4 100 parts of the L-lysine salt of N-lauroyl-DL-glutamic acid and 5 parts water were mixed, milled, and further processed as in Example 1.

The product had a solubility value of 95, good detergency, and skin protecting properties.

EXAMPLE 5 80 parts monosodium N-lauroyl-DL-glutamate, 15 parts of N methyl N lauroyl B alanine sodium, 2 parts polyethyleneglycol (M.W. 400), and 5 parts water were milled and converted to a detergent bar as in Example 1.

The solubility of this product was 64. It had good detergency, and excellent protective properties for the skin.

EXAMPLE 6 5 parts water were added to 100 parts of a monosodium N-acyl-DL-glutamate prepared by reacting DL-glutamic acid with mixed fatty acid chlorides derived in a. ratio of 20:30:50 from beef tallow oil fatty acids, coconut oil fatty acids, and lauric acid, and neutralizing the reaction product with sodium hydroxide. The aqueous solution of the acylation product had a pH of 5.5. The mixture of water and N-acylglutamic acid was milled and further processed as in Example 1.

The detergent bar obtained had a solubility value of 50, showed good detergency, and gave a soft and smooth feeling to the skin after use.

EXAMPLE 7 100 parts monoammonium N-lauroyl-L-glutamate were added to 7 parts water, and the mixture was milled and further processed as in Example 1.

The detergent bar so produced had a solubility value of 75, gOOd detergency, and skin protecting properties.

EXAMPLE 8 Detergent bars were prepared by the method of Example 1 from the following four compositions:

The several products so obtained were tested for their solubility values and for their surface activity. Foam performance was evaluated as the foam height in centimeters estimated according to Japanese Industrial Standards K-3362-1955 for a 0.25% solution in water at 40 C. The wettability values were estimated by measuring the falling time (seconds) of a 0.25% solution at 40 C. according to the canvas wetting method. The lime soap dispersing power was determined for a 0.25% solution by the test described in the Journal of The American Oil Chemists Society [27 (1950) Relative surface tension was determined in a 0.25 solution at 40 C. by means of a Du Nouy tensiometer.

The test results are listed in the following table.

80 parts monosodium N-acyl-DL-glutamate having acyl groups derived from fatty acids of hydrogenated tallow, 20 parts monosodium N-acyl-L-glutamate having acyl groups derived from soybean fatty acids, and 5 parts Water were milled and made into a detergent bar as in Example 1.

The solubility value of the detergent bar was 78. It had good detergency and skin protecting properties.

EXAMPLE 10 parts monosodium N-acyl-DL-glutamate whose acyl groups were those of a synthetic fatty acid mixture prepared by oxidizing parafiin, 40% C C and 60% 0 C were added to a mixture of 10 parts water and 3 parts polyethyleneglycol (M.W. 400). The mixture was milled and converted to a detergent bar as in Example 1. The material had a solubility value of 66, showed good detergency and skin protecting properties.

EXAMPLE 11 For comparison purposes, 10 parts water and 100 parts sodium N-lauroylsarcosinate were milled and compressed as in Example 1 to prepare a detergent bar. The bar was very hard and had many cracks. It disintegrated rapidly when immersed in warm water.

What we claim is:

1. A detergent bar consisting essentially of a water soluble, milled, mono-salt of an N-acylglutamic acid or N-acylaspartic acid having detergent properties, the acyl group of said acid being the acyl radical of a saturated or unsaturated fatty acid having 8 to 22 carbon atoms, and the cationic moiety of said mono-salt is selected from the group consisting of sodium, potassium, ammonium, lysine, ornithine, and lower alkanolamine.

2. A bar as set forth in claim 1, wherein said salt is a salt of an N-acylglutamic acid.

3. A method of making a shaped solid detergent bar which comprises milling a mixture of water and of a water, soluble mono-salt of an N-acylglutamic acid or N-acylaspartic acid, and compacting the milled mixture into a shape retaining solid bar, the amount of said water being suflicient to facilitate said compacting so that said bar does not disintegrate when immersed in Water at 40 C.

References Cited UNITED STATES PATENTS 2,463,779 3/1949 Kester 260-404 5 2,868,731 1/1959 Henderson et a1. 252-117 FOREIGN PATENTS 903,431

6 OTHER REFERENCES Chemical Abstracts, vol. 50, p. 128186 (1956).

LEON D. ROSDOL, Primary Examiner A. I. RADY, Assistant Examiner US. Cl. X.R.

8/ 1962 Great Britain 260-404 10 252--174, DIG 16; 260404