2~8 The present invention relates to compositions and methods for curling hair and for straightening hair, wherein the compositions contain, as the principal active ingredient thereof, guanidine hydroxide.
Commercial products based upon compositions containing thioglycolates, sulfites or alkali metal hydroxides, such as sodium hydroxides, have been widely used to permanently straighten unstraight hair, especially to straighten unstraight Negro hair. Of these products, the thioglycolate compositions and the sulfite compositions which have been commercially marketed have been relatively ineffective, with the hair in many cases reverting at least partially to the original unstraight form. While very effective in producing the desired straighten-ing effect, sodium hydroxide compositions are very harsh to both the scalp and the hair, and the use of such compositions has resulted in numerous instances of scalp irritation and/or burning, and has also resulted in a substantial reduction of the strength of the treated hair, and even, in some instances, considerable hair loss.
Various guanidine compounds have been evaluated by the prior art ln hair waving or hair straightening compositions.
Of these guanidine thioglycolate appears to have had the most attention by researchers in this art. See, for example, Shansky, American Perfumer and Cosmetics, Volume 78, August, 1963, 32-34;
Bogaty et al, American Perfumer and Cosmetics, Volume 78, November, 1963, pages 45 - 47; and Shansky, American Perfumer and Cosmetics, Volume 78, December, 1963, pages 29 - 30.
. *3 _3 ' Various organic bases including guanidine have been found to accelerate the dehairing effect of calcium hydroxide suspensions. See, e.g. Barry, "Delipatories~
Cosmetic Science and Technology, Edited by Balsam and Sagarin, 2nd Edition, Volume 2, Chapter 18, page 39, 45, Wiley Interscience, New York, 1972 and Barry "Depilatories"
Cosmetic Science and Technology, Edited by Sagarin, First Edition, Chapter 20, page 461-462, Interscience Publishers, New York, 1957, and references cited therein.
~628~
U. S. patent 3,157,578, November 17, 1964, discloses compositions for the permanent waving of human hair utilizing a solution containing, e.g. thioglycollic acid and guanidine carbonate. These compositions are employed in the form of aqueous solutions having a pH
value of from 7 - 9, with the guanidine used to replace ammonia used previously thereto, both to function as a neutralizing agent for the acid reducing agent, and also in the form of ammonium carbonate for pH control.
U. S. patent 3,861,868 of January 21, 1975 acknowledges, in column 1 thereof, earlier abandoned applications relating to the use of guanidine salts in hair dying compositions and hair bleaching compositions.
British patent 1,274,565 of May 17, 1972 discloses a process for the straightening of human hair wherein the hair straightening is conducted in two separate stages. In the first stage, a known keratin softening substance, such as an alkali hydroxide, sulfite or bisulfite, or a salt of a mercaptocarboxylic acid, is permitted to act upon the hair. After the extensive removal of the keratin softening component, a media containing a swelling substance is applied to the hair. Suitable swelling agents include monovalent aliphatic alcohol, aromatic alcohols, aliphatic diols, ether alcohols, sulfoxides, sulfones, thiocyanates, thiourea and urea, and water-soluble derivatives thereof.
11~6288 U. S. patent 3,865,930 of February 11, 1975 discloses a permanent wave composition based on a two-stage operation, wherein in the first stage the S-S
linkages of the keratin fiber are opened at an alkaline pH with the addition of a reducing agent such as a thiol. The hair is then treated in a second stage with an oxidizing or neutralizing agent to reconstitute the S-S bridges, so as to impart to the hair the desired configuration. The patent relates to a composition for the aforesaid second stage, wherein the S-S bridges are reformed. This composition is a two-component composition, with one component based on a water-soluble sulfite, bi-sulfite, metabisulfite or thiourea, and the other ; component is hydrogen peroxide.
U. S. patents 2,817,342 of December 24, 1957 and 2,840,086 of June 24, 1958 relate to permanent waving compositions based upon sulfite-type materials. Among other acid sulfites disclosed are an acid solution of guanidine bisulfite, formed by bubbling sulfur dioxide gas into an aqueous solution of guanidine carbonate.
Japanese patent 76-9013 discloses hair waving or straightening treatments wherein the hair is initially treated with a weak alkali, followed by a treatment with a chelating metallic salt solution. Calcium oxide or calcium hydroxide is used as a chelating agent to prevent mutual 11~`6~
interactions of the active ingredients.
U.S. Patent 2,836,543 of May 27, 1954 discloses the use of yuanidine as a swelling agent component in a hair setting composition. The composition also includes a water-soluble sulfite and a polyfunctional aromatic additive compound, such as genetistic acid, which acts as an accelerator.
U.S. Patent 3,642,429 of Fehruary 15, 1972 is directed to a hair treatment composition based on a polycondensate of methylol compounds and an urein compound. The generic formula for the urein compound appears to encompass guanidine, but guanidine is not named in that patent.
U.S. Patent 3,686,296 is directed to depilatories which are nitrogen-based thioglycerol molecular complexes. The nitrogen base may be, e.g. guanidine or guanidine hydrochloride.
SUMMARY OF THE INVENTION
The present invention is based upon the discovery that human hair straightening or relaxing compositions, which exhibit improved hair strength retention and significantly reduced scalp irritation, compared to relaxing compositions based upon alkali metal hydroxides, may be formulated with the use of guanidine hydroxide as the principal active ingredient. As used herein the term principal active ingredient means that the defined ingredient is present in an amount of more than 50 by weight with the possibility of other active ingredients being present in minor amounts. These compositions exhibit so-called "permanent relaxation", a relaxing effect which las-ts until new hair -~:
- . .
~1~62~8 growth requires the repetition of treatment.
The hair is preferably treated by applying thereto the aqueous reaction product formed by reacting, in an aqueous medium, at least one water-soluble inorganic hydroxide, preferably an alkaline earth metal hydroxide, such as calcium hydroxide, and at least one water-soluble guanidine salt, such as guanidine carbonate. After a suitable time, conveniently about 5 to 45 minutes, the composition is removed from the hair. Preferably, the treated hair is fixed or neutralized while the hair is maintained in a substantially straightened configuration.
Generally the pH value of the hair will be reduced to no greater than about 7 during this step, and preferably the pH of the hair is reduced to about 5.0 to 6.5, although lower pH values may be used if desired.
Furthermore, th~ guanidine hydroxide compositions have been found to be surprisingly effective in so-called "permanent wave" applications, wherein such compositions exhibit the same advantages of effectiveness, reduced irritability, and high strength retention, as noted for the hair relaxer compositions of this invention. Also, the sulfur dioxide, mercaptan, and/or ammonia smell noticed with conventional, commercial waving compositions will not be noticed with the compositions of the present invention.
The guanidine hydroxide is preferably formed by reacting the 11C~6;~8~
aforesaid hydroxide and the aforesaid guanidine salt in an aqueous medium, and the resulting aqueous reaction product is applied to curled hair, Preferably the hair is deformed during the treatment time by being maintained on curlers.
After the desired treatment time with the guanidine hydroxide composition has elapsed, the composition is removed from the hair and/or the hair is neutralized with a neutralizing solution, such as an acidic shampoo.
The curlers may be removed from the hair for the rinsing and neutralizing steps, or these steps may be accomplished while the hair is maintained on curlers, as is known to the art. Thereafter, the hair will normally be dried using a blow dryer.
' - ' 11~`6288 DETAILED DESCRIPTION OF THE INVENTION
. . .
~air Relaxing Composition and Method Unstraight hair is straightened by contacting the hair with a straightening amount of an aqueous setting composition, and straightening the hair during at least a portion of the time the composition is in contact therewith. The straightening composition is preferably formed by reacting in an aqueous medium at least one water-soluble inorganic hydroxide with at least one guanidinesalt, the anion of which forms a substantially water-insoluble salt with the cation of the hydroxide.
l The preferred straightening composition of the present invention is a two-component composition, as the resulting aqueous reaction product has only limited shelf stability under normal conditions. One of the components is a water-soluble hydroxide, preferably a hydroxide which is at least as soluble in water as calcium hydroxide.
Lithium hydroxide may be used, but the preferred hydroxides are alkali metal hydroxides, especially calcium, barium or strontium hydroxide or mixtures thereof. Availability, cost and effectiveness make calcium hydroxide the most preferred hydroxide. It should be pointed out that the oral toxicity of barium hydroxide makes that hydroxide much less preferred than calcium hydroxide.
11~628B
It appears that the reaction between the inorganic hydroxide and the guanidine salt is an equilibrium reaction, and if the anion of the guanidine salt does not form a substantially water-insoluble salt with the cation of the hydroxide, then the reaction to produce guanidine hydroxide will not b