US2717850A - Disinfecting and cleansing solution for the human skin - Google Patents

Description

United States Patent DISINFECTIN G AND CLEANSING SOLUTIGN FOR THE HUMAN SKIN Adolf Schmitz', Essen, Germany No Drawing. Application July 27, 1951, Serial No. 239,003

1 Claim. (Cl. 167-22) This invention relates to disinfecting and cleansing solution for the human skin; and it comprises an aqueous disinfecting solution for the human skin in which the active disinfecting agent consists of a water-soluble acid salt of a high molecular amino acid having the formula:

C12H25 NH CHzCHzNH CHzCHzNH CH2COOH said solution having a pH corresponding substantially to that of the skin; all as more fully hereinafter set forth and as claimed.

Surface-active substances are classified by the nature of their electric charge or the presence (or absence) of ionogenic groups and are accordingly divided into substances of anionic, cationic, amphoteric or nonionogenic character. Of these substances, the surfaceactive substances of anionic and non-ionogenic character are more or less extensively employed for cleaning of textile materials as well as for body cleansing, while the cationic surface-active substances have been found unsuitable for such purposes. Amphoteric surface-active substances have also been suggested for cleaning textile materials and have furthermore been used as additions in soaps and cosmetics.

Of the four-named types of surface-active substances, the anionic substances possess a very slight bactericidal action which is insufficient for practical purposes. The non-ionogenic substances totally lack any bactericidal action. The cationic substances, on the other hand, possess a good disinfection action so that such substances have primarily found use in the disinfectant field. However, previously little was known concerning the disinfecting action of amphoteric surface active substances.

In disinfection, for example, the disinfection of the hands, it is of special importance that the disinfection is assisted by good cleansing of the skin to remove the adhering germs. It is therefore necessary in surgery that the disinfection of the hands with cationic-active substances, for example, quaternary ammonium compounds, be preceded by a cleansing with anionic surface-active agents, which for practical purposes were the only substances suitable for thorough cleansing. This method, which is necessary because of the insufficient cleansing action of cationic surface-active agents, not only has the disadvantage that two different substances must be employed successively but also has the defect that the bactericidal action of the cationic surface-active substance is destroyed by anionic surfaceactive substances. Consequently the soap or other anionic surface-active agent which remains after the first treatment renders the disinfection of the second treatment with cationic surface active agents illusionary.

This defect of the quaternary ammonium compounds, which was recognized soon after the discovery of their bactericidal action, has led to many attempts to improve their washing or cleansing action, and consequently, for example, mixtures of quaternary ammonium compounds and salts of high molecular amines have been recommended. Furthermore, alkylated polyalkylenepolyamines have been described as good washing and disinfecting means. However, a satisfactory solution to this problem had previously not been achieved.

The cleaning action of a surface-active agent upon inanimate materials, such as textiles, as well as the bactericidal activity of substances upon such materials does not in itself serve as a true indication of their suitability for cleansing and disinfecting the human body.

Most surface-active agents which have been found suited for cleaning materials, such as textiles, have been found practically unsuited as body-cleansing agents. Whereas in the cleaning of textiles all particles of dirt and grease must be completely removed, in some cases with the assistance of strong mechanical action, careful treatment is required in the cleansing of the skin and excessive removal of fat from the skin and swelling are to be avoided. The natural prophylatic functions of the skin, such as the acid coating which hinders the growth of bacteria and their penetration into the pores, the sebaceous matter upon which the smoothness and suppleness of the skin depend and the horny substance of the upper layer of the skin which resists abrasion, should remain undamaged as a consequence of cleansing, as otherwise disadvantageous efiects may be produced upon the entire organism. Thus, for example, it has been found that the sulfuric acid esters of higher fatty acids, which are very suitable for wash ing textiles and other inanimate materials, cannot be employed as skin-cleansing agents as they cause very considerable roughening and cracking of the skin and, in this way, actually favor the accumulation of dirt and bacteria on the skin washed therewith.

Consequently, the range of substances which can be employed for body-cleansing purposes is very limited. Previously practically only normal soaps have been employed for skin cleansing and for the care of the body, while other synthetic media which are normally employed in the textile industry and which have been proposed for cleansing the skin and care of the body have not been found well suited therefor.

While cationic surface-active agents, as has been indicated above, having strong bactericidal action, they are not without their drawbacks when employed for disinfection of the body. Their bactericidal activity is substantially diminished in the presence of albumen. Furthermore, cationic active substances such as the quaternary ammonium compounds cause precipitation in albumen solutions, which evidently is one of the reasons that they are not especially compatible with the skin and easily cause reddening and irritation of the skin.

It is an object of the present invention to provide novel compositions which simultaneously have excellent body cleansing and disinfecting properties.

In accordance with the invention it was unexpectedly found that a certain class of amphoteric surface-active agents possesses not only good body cleansing but also good disinfecting properties when employed in the form of aqueous solutions of their salts with organic or inorganic acids. These amphoteric surface active agents are the water soluble acid salts of a high molecular amino acid having the formula:

C12H25 NH CHzCHzNH- CHzCHzNH CHzCOOH These compounds have unexpectedly been found, contrary to most synthetic surface-active cleaning agents, not only to be admirably suited for body-cleansing purposes but also to surpass all previously used and known cleansing agents in this respect.

As the amphoteric substances in accordance with the invention can be adjusted to the pH of the skin, swelling of the skin such as, for example, occurs with the alkaline reacting normal soaps can be avoided. Consequently the amphoteric substances do not alter the pH of the skin cleansed therewith. Furthermore, even with constant use they do not lead to roughening of the skin as, because of their amphoteric character, they do not, as is the case with fatty alcohol sulfonates, disturb the dissociation equilibrium of the similarly composed skin albumen.

The excellent dirt-carry capacity of the amphoteric surface-active agents in accordance with the present invention is a further marked advantage of such substances.

The dirt-carrying capacity of the surface-active agents in accordance with the invention surpasses that of both the cationic and the anionic groups of surface active substances, as is shown by the determination thereof by a method of E. M. C. Liesegang (Fette und Seifen 1940, volume 47, page 458). This method permits an exact comparison of different substances and gives a number which is lower as the dirt-carrying capacity of the tested substance is higher. Thus the following numbers were obtained for substances of comparable chemical structure:

Dirt-carrying capacity of the 10% solution according Amphotertc surface-active substances to Llesegang of the type according to the invention 10-15 Cationic surface-active substances 20-25 Anionic surface-active substances 15-30 The dirty-carrying capacity of surface-active substances is of prime importance in body cleansing. Body-cleansing agents having a low dirt-carrying capacity can remove dirt particles from the skin but readily allow them to fall back when diluted with water, as occurs during rinsing. If the poor dirt carriers are good wetting agents, as is the case, for example, with sulfonates, the dirt is actually not removed from the skin but is washed into the wetted fine crevices and hair outlets in the skin, accumulates therein, and can be removed only with difiiculty, generally only by the mechanical action of a brush.

The amphoteric body-cleansing agents according to the invention have a very strong disinfecting action and are able to destroy bacteria in a short time even when greatly diluted. Contrary to the cationic surface-active agents, such as the quaternary ammonium compounds, their bactericidal activity is only slightly affected by the presence of albumens and even in strong albumen solutions, such as blood serum, they have only a slightly lowered activity. Furthermore, the amphoteric substances in accordance with the invention are very compatible with the skin and have substantially no irritating effect.

The following example will serve to illustrate the manufacture of body-cleansing agents in accordance with the invention.

Example 1 mol of monodecyldiethylenetriamine was reacted with a solution of the sodium salt of monochloracctic acid to produce an amino acid of the following formula:

An aqueous solution of this acid was treated with an equivalent of lactic acid to produce the corresponding lactate.

The acid salts of the above amino acid have excellent cleansing and disinfecting properties. Preferably they are prepared in the form of their aqueous solutions, the pH of which is adjusted to about that of the skin. Preferably they are not combined with fats or oils or soaps, as the presence of these compounds reduces their disinfecting action.

This application is a continuation-in-part of my application Serial Number 115,566, filed on September 13, 1949 and now abandoned.

I claim:

An aqueous disinfecting and cleansing solution for the human skin in which the active disinfecting agent consists of a water-soluble acid salt of a high molecular amino acid having the formula:

O to that of the skin.

References Cited in the file of this patent UNITED STATES PATENTS Schoeller et al. Dec. 28, 1937 Guild Dec. 1, 1942 OTHER REFERENCES Hyamines 1622 and 10-x, Rohm & Haas Co., 1947, pp. 4-5.