Depilatory Compositions

The invention described herein relates to a depilatory composition comprised of an accelerator, biguanide, and an active thiol agent.

The use of thiol-based depilatory agents, such as thioglycolic acid, for removal of unwanted body and facial hair is well established in the art. These agents react by reducing hair's protein disulfide bonds to sulfhydryl anions, thereby allowing easy removal of the weakened hairs when washed or wiped away. However, in using thiols, it was discovered that certain conditions facilitated the effectiveness of this reaction. One such condition is high alkalinity to provide ionized reactants. Not only do the high pH's (approximately 12.0-12.5) result in ionized thiols, but they also result in increased penetration of a reactant. Thus, substances to provide further enhancement of penetration by active thiols were developed.

Further progress in the area of depilation resulted in the development of compounds which seem to expose more of the disulfide bonds to thiol agents. It is thought that these compounds decrease inter and intra chain bonding in hair keratin thereby, "accelerating" the rate of penetration and thus reaction by the thiols. Ureas, thioureas, and guanidines are thought to react as such accelerators, and in fact, the prior art discloses many of these nitrogen-based depilatory accelerators. Among such prior art references are U.S. Pat. No. 2,192,380, March 5, 1940 to David Walker Jayne, Jr.: U.S. Pat. No. 3,194,736, July 13, 1965 to Ernest Brown & John E. Logan; Belgian Pat. No. 765,987, May 5, 1970 to Investigations Scientifiques Pharmaceutiques; U.S. Pat. No. 3,981,681, Sept. 21, 1976 to Mario de la Guardia; U.S. Pat. No. 3,271,258, Sept. 6, 1966 to Charles Zviak and Jean Rouet; U.S. Pat. No. 4,177,260, Dec. 4, 1977 to Theodor Wajaroff; French Pat. No. 2,168,202, Jan. 20, 1972 to Fabres SA P.; U.S. Pat. No. 3,686,296, Aug. 22, 1972 to Harvey A. Yablonsky; and U.S. Pat. No. 3,728,356, Aug. 17, 1973 to Harvey A. Yablonsky.

In addition to the above-mentioned disclosures, biguanides have been chemically reacted with ethylene sulfide to form thiol depilatory derivatives, U.S. Pat. No. 2,453,333, Nov. 9, 1948 to Leonard P. Moore and Walter P. Ericks. In addition, U.S. Pat. No. 2,174,497, Sept. 26, 1939 to William H. Hill discloses a method of unhairing hides and skins by combining biguanide with an alkaline hydrolyzing agent. However, no thiol depilatory with biguanide as an accelerator is suggested by Hill.

The present invention provides not only more effective and faster removal of unwanted body and facial hair than urea accelerators, but the combination of biguanide with a thiol depilatory is safer for human usage in comparison to guanidine and thiourea accelerators.

It is an object of the present invention to provide safe and effective removal of unwanted body and facial hair. It is a further object to provide depilatory compositions containing biguanide and an active thiol depilatory agent. These and other objectives will become readily apparent from the detailed description which follows.

All percentages and ratios used herein are by weight unless otherwise specified.

This invention relates to depilatory compositions which use biguanide as an accelerator for active thiol depilatory agents.

The depilatory composition of the present invention not only is safer than guanidine and thiourea compounds, but it also reduces depilation time. This reduction in time for removal of unwanted hair is advantageous for several reasons. First of all, the average person using such compositions prefers reduced time of depilatory action. Secondly, this reduction permits less exposure of skin to possible irritation due to high alkalinity or exposure to thiol actives.

The increased rate of hair removal obtained by the present invention is believed to be due to the acceleration by biguanide, allowing the thiol active to more readily exert its depilatory effect.

The composition of the present invention is based upon three essential ingredients, biguanide, a thiol depilatory, and water.

Biguanide, formula presented in the figure below, can be used in base or salt form at concentrations providing from about 0.01M to about 2.0M biguanide, preferably from about 0.5M to about 1.0M biguanide. Suitable salts of biguanide include the hydrochloride form, sulfate form, bicarbonate form, and mixtures thereof ##STR1##

The thiol active may include one or more thiol acids, (e.g. thioglycolic, thiolactic and .beta.-mercaptopropionic acid), or the alkali and/or the alkaline-earth metal salts of these acids. In addition, other active thiol agents can be used. These include .alpha.-mercaptoethanol, thioglycerols, 1,3-dithio-2-propanol, 1,4-dithio-2-butanol, 1,4-dimercapto-2, 3-butanediol, 1,3-dithio-2-methoxypropane, 1,3-dimercapto-2-aminopropane, 1,4-dimercapto-2,3-diaminobutane, aminoethanethiol, and related effective thiol actives. The thiol active is present at a concentration of from about 0.1M to about 2.0M, preferably from about 0.2M to about 1.0M.

Mixtures of thiol actives also may be used in the compositions described herein.

Water from about 10% to about 80%, preferably from about 20% to about 70%, makes up the third essential component of the present invention.

The pH of the present depilatory composition should range from about 10.5 to about 12.5, preferably from about 11.0 to about 12.3 at 25.degree. C. These pH's preferably are achieved through the use of an alkaline material such as calcium hydroxide.

The present invention can be embodied in several commercial forms such as creams, lotions, gels, aerosols, or the like. If the present invention is put into such forms, a number of optional ingredients would be added. These ingredients include from about 0% to about 5% of a suitable filler such as chalk, magnesium oxide and carbonate, clays, talc, fumed silica and mixtures thereof. Emulsifiers such as anionic surfactants (e.g., fatty alcohol sulfates and/or alkyl aryl sulfates), nonionic surfactants, and mixtures thereof, present at levels of from about 0% to about 20%, are also useful. Often chelating agents to complex with metals are included in such compositions. One suitable example of such a chelator is ethylenediaminetetraacetic acid, its salts and mixtures thereof.

Among the other ingredients useful in these various embodiments is a gelling agent or thickener, present at levels of from about 0% to about 30%. The thickeners used could include both natural and synthetic ones such as tragacanth, xanthan, karaya, and guar gums, clays, methyl or hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, fatty and polyvinyl alcohols, modified starches and sugars, and mixtures thereof. Emollients such as paraffin, petrolatum, mineral oil, fatty alcohols, silicone oils, and mixtures thereof, present at levels of from about 0% to about 60%, can also be included. Fragrance and coloring generally provide the remaining ingredients.

When the present invention is in an emulsion form, it may be either a water-in-oil or oil-in-water emulsion:

The following are examples of compositions of the invention described herein. They are merely illustrative of the present invention and are not limitative thereof:

Another embodiment of the present invention is as an aerosol. In such a form, the depilatory would include previously-listed optional ingredients as well as propellants. The following example presents such an aerosol. Again, it is meant merely as an illustration of the present invention and not limitative of that invention: