US2202741A - Detergent composition - Google Patents

Description

Patented May 28, 1940 UNITED STATES DETERGENT COMPOSITION Robert W. Maxwell, Wilmington, Del, asslgnor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing.

Application August 24, 1937,

Serial No. 160,675

1 Claim. (01. 87-5) This invention relates to the manufacture of substituted acids, but this invention is not condetergent compositions and particularly to solid c'erned with methods by which such materials detergent compositions such as soaps or, preferably, fatty alcohol sulfates.

It is well known that ordinary soap in bar or cake form has the objection of becoming slimy or soft when left in contact with water. It has also been found that detergents of the fatty alcohol sulfate type (which are commonly marketed in the form of their sodium salts) are difficult to convert into bars or cakes since high pressures are required to shape such materials, and the shaped forms tendto deform under the pressures required. Furthermore, such molded fatty alcohol sulfate type detergents tend to disintegrate in contact with water and lose their cake form. This results in inconvenience and waste in use.

This invention has as an object the preparation of an improved solid detergent. A further object is the preparation of improved solid soaps. A stillfurther object is the preparation of improved solid fatty alcohol sulfate detergents. A still further object is the preparation of these detergents in bar form. Other objects will appear hereinafter.

These objectsare accomplished by the following invention wherein there is incorporated into the solid soap or fatty alcohol sulfate detergent, an alkali metal-salt of a carboxyalkyl ether of a polymeric carbohydrate having in its molecule at least ten simple carbohydrate units.

In investigating the difficulties and disadvantages of solid detergents as outlined above, it has been found that soap and in particular fatty alcohol sulfate type detergents can be molded without the objections mentioned above if a relatively small amount of a suitable binder is incorporated, and that the alkali metal salts of carboxyalkyl ethers of polymeric carbohydrates containing at least ten simple carbohydrate units are "effective binders for this purpose. Products falling in this classification include the sodium salt of celluloseglycolic acid ether and the sodium salt of starchglycolic acid ether. These materials may be represented by the following formula: RDCHzCOONa. where R represents the cellulose or starch nucleus, the hydrogen of at least a part of the free cellulose or starch hydroxyl groups having been replaced by carboxyalkyl groups. These materials can be dispersed in water, giving viscous colloidal solutions which have high adhesive and binding strength. These materials may be prepared by treating alkali cellulose or alkali starch with the sodium salts of halogen can be prepared.

The more detailed practice of the invention is illustrated by the following examples, wherein parts given are by weight unless otherwise stated. There are of course many forms of the invention other than these specific embodiments.

Example I Twenty-six and one-half parts of a 19% aqueous dispersion of sodium starchglycolate was placed in a kneading machine of the Werner- Pfleiderer type and 95 parts of a mixture of equal parts of sodium dodecylsulfate and sodium sulfate was added. This mixture is typical of a commercial detergent based on a sulfated fatty alcohol. The mass was kneaded for minutes in the mixer or until homogeneous after which samples were withdrawn and subjected to pressure in a hydraulic press at room temperature. The resulting cake containing 5% binder based on the solids content was firm and was much more slowly disintegrated by water than a control sample having no binder.

Example II To 26.5 parts of a 19% aqueous dispersion of sodium starchglycolate in a kneading-type mixer was added 95 parts of ordinary soap powder, and the mass was worked in the mixer until homogeneous. The mixture was then dried in a steam oven at 95 C. for two hours to remove a portion of the water after which samples were pressed in a hydraulic press to convert into cake form. This composition contained 5% binder based on the solids content.

Example III pending on the physical properties desired in the molded soap, and the invention is not to be limited to the proportion given in the above examples. Other methods of incorporating the above binders in soap compositions may be employed such as simple mixing in a soap kettle or a crutcher.

This invention covers the use, as binders for bar soap, of water dispersible alkali metal salts of carboxyalkyl ethers of polymeric carbohydrates or their low-substituted ethers or esters, said carbohydrates containing at least ten simple carbohydrate units. Carbohydrates falling in this classification include cellulose, starch, glycogen, and inulin, as well as their low-substituted derivatives such as ethers and esters, for example, methylcellulose or methylstarch. Thus, in addition to cellulose or "starch, a low-substituted methylcellulose or methylstarch may be treated with alkali and monochloroacetic acid to give a carboxymethyl ether of a methylcellulose or a methylstarch. Monohalogen substituted acids other than ehloroacetic acid may be used, for example, chloropropionic or chlorobutyric acids, etc. Ethers derived from alpha-halo en substituted acids are preferred, however. 11 general, chloro acids of low molecular weight give products, the alkali metal salts of which have better water dispersibility than those obtained using chloro acids of higher molecular weight, the upper limit in molecular weight being that point at which the alkali metal salt of the carboxyalkyl derivative of the polymeric carbohydrate is no longer dispersible in water; In most instances carboxyalkyl ethers derived from halogen acids containing more than four carbon atoms will not be useful. The invention is generic to the use in solid soap and particularly in solid fatty alcohol sulfate detergents of a wateradispersible alkali metal salt of a carboxyalkyl derivative of a polymeric carbohydrate having in its molecule a least ten simple carbohydrate units. 1

The preferred binders, however, are sodium starchglycolate and sodium celluloseglycolate. A typical sodium celluloseglycolate as used in this invention may contain from 0.3 to 1.5 glycolic acid ether groups per simple carbohydrate unit. A typical sodium starchglycolate may contain from 0.05 to 1.5 glycolic acid ether groups per simple carbohydrate unit. The invention is generic to alkali metal solid detergents including sodium and potassium soaps and fatty alcohol sulfates. The invention is, however, of particular value in connection with sodium salts of fatty alcohol sulfates, e. g., the sodium salts of sulfated long chain alcohols such as dodecyl, myristyl, cetyl, stearyl, and 9,10-octadecenyl alcohols regardless of whether sulfation has taken place on the hydroxyl group or at the double bond in case a double bond is present.

The products of this invention are useful as toilet, laundry, and medicated soaps, and in general for the common uses for which soap is utilized.

Soap and detergent compositions containing the products of this invention as binders possess a number of desirable properties not heretofore obtainable. Thus, detergents of the fatty alcohol sulfate type are difllcult to convert into cake or bar form without binders since high pressures are required to shape these materials, and the shaped articles disintegrate easily in contact with water. The products of the present invention disintegrate much more slowly in contact with water and in addition have a superior feel and appearance. These binders, due to their colloidal nature, also act as stabilizers for the foam produced when the soap is dissolved in water, the

result being a foam of creamy texture which is u more permanent than foam from untreated soap orv detergent compositions. The tendency for bar soap to become slimy when left in contact with water is reduced when binders of the type described above are incorporated. The binders also act as perfume fixatives.

-The above description and examples are intended to be illustrative only. Any modification of or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claim.

I claim: v A solid detergent in bar form, the solid components of which consist of sodium dodecylsulfate, sodium sulfate, and, as a binder, sodium starchglycolate.

ROBERT W. MAXWELL.