Bleaching and dyeing; fluid treatment and chemical modification – Dyeing involving animal-derived natural fiber material ,... – Hair dyeing
Reexamination Certificate
1997-08-20
2002-08-06
Hardee, John (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Dyeing involving animal-derived natural fiber material ,...
Hair dyeing
C252S186290, C252S186310
Reexamination Certificate
active
06428580
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of ascorbic acid in hair care compositions, particularly in permanent waving and hair coloring compositions. More specifically, the invention relates to an oxidation system containing ascorbic acid, at least one metal ion, and an oxidizing agent which, when used in the inventive composition, is capable of generating an oxidizing potential of from about 100 to about 500 millivolts at a pH ranging from about 2 to about 10. The invention is also drawn to permanent waving and hair dyeing kits.
BACKGROUND OF THE INVENTION
In permanent hair waving, the hair is first treated with a reducing composition capable of breaking the disulfide bonds of the hair keratin (S—S) and causing the formation of sulfhydryl groups (—SH). In other words, the amino acid cystine in the hair is converted to cysteine. The hair is then re-shaped in a new form under applied mechanical tension, either by winding on rods (waving) or by combing through (straightening). The hair, while still under mechanical tension, is then subject to a neutralization step, during which the hair is treated with an oxidizing composition. The oxidizing composition causes the disulfide bonds of the hair keratin to be restored, i.e., reforming the amino acid cystine, and the hair now is capable of retaining the new configuration permanently.
The hair may be damaged if, during the neutralization step, hair is subjected to oxidants that are too strong. Over-oxidation generates cysteic acid instead of restoring the amino acid cystine. The presence of cysteic acid is undesirable because it does not allow the reformation of the disulfide bonds, resulting in weak, damaged hair.
In the art of permanent waving, the two most commonly used materials for quenching or neutralizing a permanent wave process are hydrogen peroxide and bromate salts. Each has its drawbacks. In permanent hair waving, the first step usually takes place at an alkaline pH of 7.5-10.0. The application of hydrogen peroxide, which is conventionally quite acidic, at pH 2.5-5.0, causes stress to the hair. Further, hydrogen peroxide may also “lift” the natural color of the hair and cause undesirable red undertones to develop. Bromate salts are used in some Asian countries as they will not redden hair like hydrogen peroxide. However, bromates are dangerous compounds in that they are explosive and ignitable.
Ascorbic acid, also known as Vitamin C, is widely used in the pharmaceutical industry and the cosmetic industry because of its biological activity. Attempts have also been made to use ascorbic acid in permanent waving of hair, both to break and to restore the disulfide bonds.
For example, in U.S. Pat. No. 2,780,579 to Schwartz et al., the oxidized form of ascorbic acid, i.e., dehydroascorbic acid (DHA), is taught as a perm neutralizer. The Schwartz et al. patent states that the powerful oxidants normally used in permanent waving, such as hydrogen peroxide, bromates, chlorates and chlorites, tended to over-oxidize the reduced hair. As a result, the oxidation goes beyond the cystine stage, resulting in irreversible damage to the hair. The over-oxidation renders the hair porous and brittle, and also causes hair discoloration. If lower concentrations of these oxidants are used, an insufficient disulfide bond recovery has been observed.
According to Schwartz et al., DHA is an effective oxidant, capable of converting cysteine back to the amino acid cystine in reduced hair without over-oxidizing the hair. Schwartz et al. used a mixture of ascorbic acid with hydrogen peroxide or other oxidants in the presence of buffers, forming DHA in situ.
Further, despite the statements in Schwartz et al. regarding the effectiveness of DHA, the reaction used therein is not much different from using peroxide alone. The molar ratio of ascorbic acid to hydrogen peroxide suggested in the examples of Schwartz was very high. This ratio was determined from Schwartz as follows:
(2 oz.×29 g/oz×6%*) /(34 g/mol)=0.1 mol hydrogen peroxide
*20 vol. hydrogen peroxide=6% by weight in water
(0.25 g) /(176 g/mol)=0.0014 mol ascorbic acid.
RATIO=0.1 mol hydrogen peroxide/ 0.0014 mol ascorbic acid=72:1.
U.S. Pat. No. 5,270,337 to Graf teaches that the use of ascorbic acid and a divalent metal ion such as Cu
2
+ can effectively remove oxygen from an aqueous solution by converting the oxygen to water. In Graf, ascorbic acid reduces Cu
2+
to Cu
+
to form DHA. Cu
+
(cuprous) ions form a complex with oxygen, and an electron transfer occurs to give Cu
2+
(cupric) ions and superoxide anion radicals. The radicals, in the presence of the copper, rapidly disproportionate into oxygen and hydrogen peroxide. The copper-ascorbate complex quickly reduces the hydrogen peroxide to water without the simultaneous production of oxygen or hydroxyl radicals.
Graf's invention is mainly used as a food preservative. Further, the copper-catalyzed degradation of peroxide taught in Graf does not solve the difficulty in the art of finding an effective peroxide-free permanent wave neutralizer and/or oxidation dye developing system.
Thus, it is desirable to develop an oxidizing system that would effectively restore disulfide bonds and/or develop oxidation hair color without using peroxides or bromates. In particular, it is desirable that the oxidizing system be able to accomplish this at a pH ranging from 5 to 10, preferably from pH 7.5 to 10.0. As discussed above, the first step in the permanent hair waving process usually takes place at a pH ranging from 7.5 to 10.0. The application of an oxidation solution in a similar pH range could be expected to be less stressful on the hair, as compared to the conventionally used hydrogen peroxide at a pH ranging from 2.5 to 5.0. In addition, such a system would be more compatible with oxidation hair dyes that are being developed in this same pH range, i.e., at a pH ranging from 7.5 to 10.0. Finally, this oxidation system would also provide for better color retention in tinted hair after permanent wave treatment.
Thus it was surprising and unexpected that the present invention, a system containing ascorbic acid, at least one metal ion catalyst, and an oxidizing agent capable of generating an oxidizing potential of from 100 to 500 millivolts at a pH ranging from 2 to 10 is an effective composition useful for application in place of peroxide for hair care applications.
SUMMARY OF THE INVENTION
To achieve these and other advantages, and in accordance with the purpose of the invention as embodied and broadly described herein, the present invention, in one aspect, provides an oxidizing system based on ascorbic acid and capable of effective restoration of disulfide bonds in reduced hair during the permanent wave process. The invention also provides an oxidizing system capable of developing color in oxidation dye systems. Further, the present invention provides an oxidizing system that does not render oxidative damage to the hair during permanent wave and/or color processing.
The present invention is thus drawn to an oxidizing system for application to keratinous substances, particularly human hair, the system containing ascorbic acid, at least one metal ion, and an oxidizing agent capable of generating an oxidizing potential of from about 100 to about 500 millivolts wherein the system has a pH ranging from about 2 to about 10.
The present invention is also directed to a method for using this oxidizing system to neutralize or “quench” a permanent wave composition that has been applied to the hair. The oxidizing system of the invention is used after applying to hair an aqueous composition that serves to reduce disulfide bonds of the hair by the action of an organic mercaptan such as thioglycolic or thiolactic acid or its salts or bisulfites or phosphines. The ascorbic acid composition of the present invention is applied subsequently to re-oxidize the keratin disulfide bonds and thus to permanently reconfigure the hair.
Another aspect of the present invention is a meth
Cannell David W.
Fadeeva Natalya
Schultz Thomas
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hardee John
L'Oreal
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