US2675356A - Detergent compositions - Google Patents

Description

Patented Apr. 13, 1954 UNITED STATES PATENT OFFICE DETERGENT COMPOSITIONS No Drawing. Application October 23, 1950, Serial No. 191,716

1 Claim.

This invention relates to improved detergent compositions.

Detergent compositions, including soaps and the numerous synthetic detergents, are subject, in varying degrees, to the defect that they tend to cause skin rash or skin irritation upon prolonged contact with the hands of persons using them. This defect is particularly apparent in connection with the more efficient of the synthetic detergents, because their detergent powers are so great that they remove the natural oils from the skin of the user's hands and cause skin roughness. No satisfactory remedy for this defect has been developed heretofore.

It is an object of this invention to provide improved detergent compositions. It is a particular object of this invention to provide improved synthetic detergent compositions which will have less tendency to cause skin rash or skin irritation on the hands of the person using same. Other objects of the invention will appear hereinafter.

In accordance with this invention, there are provided solid detergent compositions comprising a detergent constituting at least 10% of the weight of the composition and from .1% to 1 based on the total weight of the composition, of a solid, crystalline urea/higher alcohol complex. The alcohols which are suitable for use in the formation of the urea complexes are the straightchain aliphatic alcohols containing at least 7 carbon atoms. The nature of these complexes is such that, for a given straight-chain alcohol, the weight ratio of urea to higher alcohol in the crystalline complex is essentially constant.

According to a preferred embodiment of the invention, the detergent composition contains from A2% to 5% of urea/higheralcohol complex, based on the total weight of the composition. Preferably .the alcohol constituent in the complex is a straight-chain aliphatic alcohol containing an even number of carbon atoms and containing from 8 to 18 carbon atoms inclusive. Cetyl alcohol is particularly preferred, for reasons pointed out more fully hereinafter. The preferred detergents for use in the compositions of the present invention are the salts of the higher alkyl sulfates, such as sodium lauryl sulfate, and, in particular, the salts of the alkylaryl sulfonic acids. The urea/higher alcohol complexes employed in the present invention are white, crystalline solids which decompose in the presence of large amounts of water. They also decompose on heating, generally at temperatures approaching the melting point of urea when no water ispresent, and at progressively lower temperatures as the amount of water is increased. The crystalline complexes are prepared by dissolving urea in a suitable solvent such as methanol, followed by addition of the desired straight-chain alcohol. As the alcohol is added, the crystalline precipitate forms quickly. Instead of actually dissolving the urea in the solvent, satisfactory results can be obtained by merely wetting the urea with the solvent. Suitable solvents for use in the preparation of these complexes include water, methanol, ethanol, propanol, tertiary butanol, ethylene glycol, propylene glycol, alcohol-water mixtures, methyl ethyl ketone, co-solvents such as ketones and esters, and the like. If desired, the adduct may be precipitated on talc or other finely divided material in order to provide a substance which is not gritty.

The mechanism whereby these urea/higher alcohol complexes are formed is not fully understood, but it is believed to involve the formation of a sleeve-like, or cylindrical, structure consisting of crystallized urea, the crystalline structure being just large enough to encircle the long, straight hydrocarbon chain of the higher alcohol. The complexes do not form readily with lower alcohols, nor do they form readily with highly branched alcohols. For a given alcohol, the weight ratio of urea to alcohol in the complex is essentially constant, regardless of the relative proportions of urea and alcohol which are present during the formation of the complex. For instance, the complex derived from cetyl alcohol contains about 75% by weight of urea and 25% by Weight of cetyl alcohol. Roughly speaking, the complexes contain about 0.75 mol of urea per mol of methylene group present in the alcohol. In preparing the complexes, an excess of either urea or alcohol may be present, but for purposes of economy, it is generally preferred to introduce the ingredients in about the ratio in which they will exist in the complex.

The alcohols useful in connection with this invention must be straight-chain alcohols, and must contain at least '7 carbon atoms. If the alcohol contains less than 7 carbon atoms, or if it is appreciably branched, it either fails to form a complex with urea at all, or else the complex is not suitable for addition to the detergents. The preferred alcohols are octanol, decanol, lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol. Saturated as well as unsaturated alcohols may be employed. Cetyl alcohol is particularly preferred because of its unusual skin-softening and healing properties.

of higher alcohol.

Data on certain of the urea/higher alcohol complexes is set forth in the following table.

1A mixture of normal primary fatty alcohols, principally lauryl alcohol, and derived by hydrogenation of coconut oil.

Technical stearyl alcohol.

All of the complexes described in the foregoing table are solublein hot methanol, ethanol and propylene glycol, and to some extent in glycerol. Solubility in the cold is less. All of these complexes much, less hygroscopic than urea itself. Urea picks up about 15% moisture in 48 hours at 86 and'75'% relative humidity, wherevas the complexes pick up an initial 2 or 3% and do not continue to absorb moisture.

The detergents, which constitute at least oi the total weight or the compositions of the present invention, include soaps, salts of the various sulfated alcohols such as sodium lauryl sulfate, salts of the hydrocarbon sulionic acids such as the sodium salts of the various alkylaryl sulionic acids and aikane sulfonic acids. N-oleyhlimethyltaurine saltsrosin'soaps, suii'ated oils, salts of the sulfonsuccina te esters, the various polyallralene oxide derivatives, the quaternary Ellil moniuzn detergents, and "the other synthetic dete-rgents which are well-known and extensively utilized in the art. The salts of the sulfated alcohols, and in particular the salts of'the sulaliiyiaryl hydrocarbons, constitute the preferred detergents, because they are highly effective as detergents in the first :place, and be cause they exhibit the greatest degree of improvernent, as regards their tendency to cause skin rash or skin irritation, when admixed with the urea/higher alcohol complexes in accordance with this invention.

Frequently the detergent compositions of the present invention will contain from to 50%, and preferably from to 49% of the active igredients of the type set'forth above. To these may be added the various builders known to the .art including alkali phosphates, alkali sulfates,

alkaii cares-hates. alkali silicates and the like.

The urea/ higher alcohol complexes may be adwith the detergents in any suitable manner, and. they do not detract in any way from the properties of the solid, untreated detergents. When the compositions of the present invention are added. to water, the course of ordinary usage, the urea/higher alcohol complex decomposes toproduce ifree urea in solution, together with an emulsion of the relatively small amount The beneficial effect resulting from the presence of the urea/higher alcohol complexes is not fully understood, but is believed to involve the known healing effect of urea, and the slain-softening and soothing efiect of the hi her alcohol, particularly in the case of cetyl alcohol. The tende-ncyof detergents to cause ndingupon the particular detergent employed,

' the quality of the water being used, andthe particu'la-r individual involved; but the addition of the urea/ higher alcohol complexes in accordance remainon the articles being washed. The opti mum amount of complex varies, depending upon the particular detergent with which it is being mixed and the type and quantity of builders employed. For practical reasons, amounts varying from about /2 to about 5% are much preferred.

In addition to the detergent itself and the urea/higher alcohol complex, the detergent compositions may, of course, contain any of the other ingredients known to' the art, including builders, coloring matters, perfumes, and the like; In this connection, it should be noted that urea itself actually is a valuable builder for soap and other detergents. The detergent portion of the compositions may consist of a mixture of several in dividual detergents, and a mixture of several of the urea complexes may be employed in a single detergent composition.

The following exarnples will serve to illustrate certain specific embodiments of the present invention.

Ercmpie 1.A urea/cetyl alcohol complex is prepared by adding urea slowly and with stirring to'a solution of cetyl alcohol in methanol at C. A crystalline, whiteprecipitate forms almost immediately. The complex is cooled, filtered, washed with acetone, dried in a stream of air and ground to size.

Example 2.-A detergent composition is prepared by uniformly admixing 97 parts by weight of MP-189 (a sodium alky'l sulfonate derived from kerosene) with 3 parts by weight of a white, crystalline complex of urea and cetyl alcohol. The properties of the original detergent are not altered in appearance as the result of the admixture, nor does the resulting composition exhibit any undue hygroscopicity. Upon being added to 'water, the composition behaves in a manner which is identical with that of the plain MP-189, except that it exhibits markedly less tendency to form skin rash on the hands of persons using the composition over long periods of time, as, for instance, in washing dishes or in washing clothes.

Example 3.-A detergent composition is pre pared by uniformly admixing 95 parts by {eight of "Damon-o1 (a sodium salt or a mixture of sulkin rash orski'n irritation, varies, of course,de--

rated higher alcohols, consisting pri cipally of sodiumlauryl sulfate) with 5 partsby weight of a white, crystalline complex of urea and lauryl alcohol. The composition is highly effective as a detergent and is less harsh than plain Dupono'l,

r 1 part by weight of :a white, crystalline complex of urea'and cetyl alcohol. "The resulting composition, when admixed with the usual coloring.

20% Oronite (a sodium salt of a mixture of alkylaryl sulfonic acids) 20% tetrasodium pyrophosphate 20% sodium tripolyphosphate 35% sodium sulfate 2% sodium carboxymethyl cellulose 3 urea/cetyl alcohol complex The resulting composition has excellent detergent characteristics, while at the same time having a minimum tendency to cause skin rash or skin irritation.

The urea/higher alcohol complexes may be admixed with the various detergents, and in particular with the sulfonate-type detergents, in amounts up to 10% by weight of the total composition without altering the appearance of the original detergent in any way. At the same time, the addition of these complexes greatly improves the properties of the detergents during their use. The complexes themselves are dry and powdery, yet they contain substances which prevent the removal of natural oils from the skin and thus keep the skin from becoming dry or rough. They combine the therapeutic properties of urea and the skin-softening action of the alcohol.

Since many modifications of the present invention will occur to those skilled in the art, it is not intended that the scope of the invention should be restricted other than by the claim appended hereto.

We claim:

A composition of matter consisting essentially of at least about 10% by weight of a solid anionic organic detergent, from about 0.1 to about 10% of a solid crystalline complex of urea and a straight-chain aliphatic alcohol containing at least about 7 carbon atoms, said complex containing about 0.75 mol of urea per mol of methylene group present in the alcohol, the remainder of said composition consisting essentially of an alkali metal salt builder.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,374,187 Flett Apr. 24, 1945 2,560,097 Emerson et a1 July 10, 1951