US2118566A - Buffered cosmetic - Google Patents

Description

Patented May 24, 1938 UNITED STATES PATENT OFFICE N6 Drawing. Application August 29, 1935,

Serial No. 38,481

8 Claims.

The present invention relates to cosmetics of the paste, cream, liquid or powder type and, in fact, any form suitable for application to the skin. Briefly stated, the improvement consists in the inclusion in the cosmetic of a buffer substance or compound in amount to maintain the preparation at a definite pH comparable to the normal pH of the skin and sufiicient to buffer the pH of the skin either to maintain its normal acidity or to adjust the pH of the skin to a condition of normal acidity.

Medical authorities concur in findings that the skin has a pH between substantially 4 and 7 and that, generally, pH 5.5 is normal and desirable for the skin of the average person. This conclusion is described by Herman Sharlit, M. D. and A. J. Highman, M. D., as set forth in volume 8, pages 515 to 519, of Archives of Dermatology and Syphilology. It will be observed that dermatologists agree that the pH of the skin. e. g. 5.5, is one of its greatest protections against bacterial infection. The reason for this is that most bacteria found in the air and which will be present on the skin live best in an alkaline medium. Hence, the maintenance of a proper pH of the skin on the acid side of neutrality is desirable in order to prevent infection.

I have found that cosmetics as now manufactured are mostly alkaline and act to reduce the protection afforded by the natural skin acidity so as to render the user correspondingly susceptible to disease. Some cosmetics contain buffer substances but their buffer action is not exhibited in the proper range of the normal skin and their presence in the cosmetic is clearly for the purpose of stabilizing the product.

It is therefore the purpose of this invention to (I) maintain the normal acidity of the skin, and (2) in cases where either acidity or alkalinity are abnormal, to adjust the pH of the skin to normal.

The inclusion of the buffer substance in cosmetics does not interfere with the value of such products but on the contrary, accelerates and enhances their usefulness in that all danger of injuring the skin of the user is eliminated and, in fact, a beneficial and protective effect is afforded.

In preparing cosmetics in accordance with this invention, they may be of any of the usual forms, for example, such asz-Face creams, cleansing cream, grease paint, liquid body make-up, mascara, toilet soap, shampoos, astringent, lipstick, dry rouge, moist rouge, face powder, eye shadow,

shaving cream, after-shaving lotion, and hand lotion.

As will be appreciated, I do not therefore care to be limited to either the physical or chemical character or form of the cosmetic with which the buffer is combined.

In like manner, buffers and their action are well understood, and I am therefore enabled to use any one or more of a multiplicity of buffer materials. The invention is therefore not limited to any specific buffer or combination of buffers and in preparing a buffered cosmetic, care need only be taken that the buffer is compatible with the cosmetic compound and is present in amount to buffer the cosmetic and to buffer the pH of the skin upon which the cosmetic is applied, and is not toxic to the user.

As examples of buffers, and simply for purposes of illustration, I mention dibasic sodium phosphate and citric acid, lactic acid and borax, malonic acid and sodium citrate or sodium phosphate and boric' acid. In fact, almost any salt of a strong base and weak acid, and a weak acid will act as a buffer.

In the case of a powder or rouge, the buifer material is controlled in amount so as to provide the desired adjustment or correction of the pH of the skin, whereas in the case. of creams, pastes and liquids, the buffer is in amount to accomplish its principal function of adjusting the pH i of the skin as well as the pH of the cosmetic product.

As one example of a cosmetic which is buffered in accordance with this invention, I prepare an astringent by forming a buffer solution consisting of 18.5 gallons of distilled water, grams of dibasic sodium phosphate and 38 grams of citric acid. This buffer solution is tested and adjusted to the desired pH, e. g., between 4 and 7, usually 5.5, and is added to a mixture of. ethyl alcohol, 4.25 gallons, menthol, 127 grams, and emoil (perfume), 2.35 gallons. The mixture is then agitated for about fifteen minutes and provides a cosmetic having a controlled pH and in which the buffer is present in amount to correct any abnormal acid or alkaline condition of the skin by adjusting the pH thereof to normal, e. g., pH 5.5. In the same manner creams and pastes are prepared. In the case of dry or powdered cosmetics, such as a face powder, the dry buffer substances are used in proper molal proportions and the talcum and buffer are thoroughly pulverized and mixed together with the other ingredients of the cosmetic before sifting.

The important consideration, it will be appreciated. is to provide a cosmetic preparation consisting of a base having distributed and dispersed is maintained at the proper acidity without interfering with the beneficial qualities of the ingredients and the bufl'er substance is capable, when the cosmetic is applied to the skin, of itself correcting and adjusting the acidity of the skin in the presence of the ingredients of the cosmetic. Hence, the buifer controls the pH of the cosmetic and at the same time is available to exert a separate. buffer action as to the pH of the skin. It is to be understood that while I have mentioned a buffer capable of maintaining an acidity of pH 4 to 7, usually pH 5.5, this may be changed in accordance with conditions.

Since the skin of most persons has a normal acidity, cosmetics prepared in accordance with this invention may be safely used for practically all cases. Where unusual or abnormal conditions exist, a test of the skin by a dermatologist is made and thereafter the cosmetic is prepared to correct either the acidity or alkalinity of the skin, as the case may be.

I have discovered, in the manufacture of creams, that these are made more adherent and free of separation of ingredients, e. g., breaking down, if the emulsion is stabilized. I accomplish this stabilization by .any suitable means but prefer an oxychloesterine compound such as lanolin. These compounds absorb substantially forty per cent by weight of water and are compatible with the usual fats and waxes employed to give the cream the desired consistency. In the manufacture of a cream of this character, lanolin and suitable fats and/ or waxes are melted and there is then added a predetermined quantity of the buffer as a solution or mixture. I prefer disodium phosphate and citric acid, although any other suitable buifer or solution may be employed. The addition or the bufier solution to the fats and waxes is carried out at a temperature of substantially 40 to 50 C. and the mixture is stirred until cool, producing a cream of desired consistency. The cream may be perfumed and the butter solution is controlled to constitute about twenty-five per cent by weight of the cream. The buffer will give to the cream base any desired pH, preferably from 4 to 7, and

usually pH 5.5, depending upon the ratio of citric acid to disodium phosphate used.

In referring herein to cosmetics, I of course mean products used externally for treatment of the skin and scalp which include a base of a liquid, pasty or creamy nature or which may be of a dry form such as powder. This base may be perfumed as desired and, in the case of moisture containing bases, the degree of moisture will be controlled as regards the physical form of the product. To such a. cosmetic base there is added the buffer which is substantially'inert with respect to the ingredients of the base and acts to control the pH thereof, at the same time, being available when the cosmetic is applied to the skin and, acting independently of the base, to adjust and correct the pH of the skin to normal.

I claim:

1. A cosmetic for application to the skin comprising a base material and a buffer composition to maintain the pH of the cosmetic at a point between 4 and 7.

2. A cosmetic of the powder type for application to the skin comprising a, base material and a bufi'er composition to maintain the pH of the cosmetic at a point between 4 and 7.

3. A cosmetic of the cream type for application to the skin comprising a base material and a buffer composition to maintain the pH of the cosmetic at a point between 4 and 7.

4. A cosmetic of the liquid type for applica tion to the skin comprising a base material and a buffer composition to maintain the pH of the cosmetic at a point between 4 and 7.

5. A cosmetic for application to the skin comprising a base material and a buffer composition to maintain the pH of the cosmetic at 5.5.

6. A cosmetic of the powder type for application to the skin comprising a. base material and a butler composition to maintain the pH of the cosmetic at 5.5.

7. A cosmetic of the cream type for application to the skin comprising a base material and a bufler composition to maintain the pH of the cosmetic at 5.5.

8. A cosmetic of the liquid type for application to the skin comprising a base material and a buffer composition to maintain the pH of the cosmetic at 5.5.

GILBERT DE WAYNE MILES.