Drug – bio-affecting and body treating compositions – Live hair or scalp treating compositions – Permanent waving or straightening
Reexamination Certificate
2000-03-01
2003-05-13
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Live hair or scalp treating compositions
Permanent waving or straightening
C424S070100, C424S070400, C424S070500, C424S070510
Reexamination Certificate
active
06562327
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions and methods for lanthionizing keratin fibers using a combination of at least one multivalent metal hydroxide and at least one complexing agent effective for dissociating the at least one multivalent metal hydroxide in sufficient quantity to effect lanthionization of the keratin fibers. In one embodiment, the process of lanthionizing keratin fibers results in relaxed or straightened hair.
BACKGROUND OF THE INVENTION
In today's market, there is an increasing demand for the hair care products referred to as hair relaxers, which relax or straighten naturally curly or kinky hair. A hair relaxer can be a product that is applied in a hair salon by a professional or in the home by the individual consumer. One of the benefits of straightening or relaxing the curls of very curly hair is an increase in hair manageability and ease of styling.
Normally, the hair relaxing process is a chemical process which alters the chemical bonds in the hair and forms lanthionine. Hair fiber, a keratinous material, contains proteins or polypeptides many of which are bonded together by disulfide bonds (—S—S—). A disulfide bond that is formed from the sulfhydryl groups (—SH) of two cysteine residues results in a cystine residue. While there are other types of bonds which occur between the polypeptides that make up hair, such as salt bonds, the permanent curling or the shape of the hair is essentially dependent on the disulfide bonds of cystine residues.
As a result, relaxing or straightening of hair can be achieved by disrupting the disulfide bonds of the hair fibers with an alkaline or a reducing agent. The chemical disruption of disulfide bonds by an alkaline agent is usually combined with mechanical straightening of the hair, such as combing, where straightening occurs through changing of the relative positions of opposite polypeptide chains. The reaction is subsequently terminated by rinsing and/or the application of a neutralizing composition.
The alkaline reaction is normally initiated by hydroxide ions. Not to be limited by theory, there are two reaction sequences that are predominantly used to explain the disruption of the disulfide bonds in hair by hydroxide ions, both of which result in lanthionine formation. One sequence is a bimolecular nucleophilic substitution mechanism where the hydroxide ion directly attacks the disulfide linkage, resulting in the formation of lanthionine and HOS. See Zviak, C.,
The Science of Hair Care
, 185-186 (1986). The second is a &bgr;-elimination reaction initiated by the attack of a hydroxide ion on a hydrogen atom located on the carbon atom that is in the &bgr;-position to the disulfide bond. Id. The result is the formation of dehydroalanine, which in turn reacts with the thiol of the cysteine or the amine group of the alanine to form lanthionine and lysinoalanine. Regardless of the mechanism, the release of hydroxide ions that can penetrate the hair drives the hair relaxing process through a cystine to lanthionine transformation. Thus, the term lanthionizing is used when one skilled in the art refers to the relaxing or straightening of keratin fibers by hydroxide ions.
Most frequently, relaxing compositions are in the form of gels or emulsions that contain varying proportions of strong bases that are water soluble, such as sodium hydroxide, or compositions that contain slightly soluble metal hydroxides, e.g., calcium hydroxide (Ca(OH)
2
), that are converted in situ to soluble bases, e.g., guanidine hydroxide. Traditionally, the two main technologies used in the hair care industry for generating hydroxide to relax keratin fibers are referred to as “lye,” or sodium hydroxide, relaxers or “no lye” relaxers. The “lye” relaxers use sodium hydroxide in a concentration range of generally 1.5 to 2.5% (0.38-0.63 M) depending on the base or carrier used, the condition of the hair, and the speed of relaxation desired. Sodium hydroxide is extremely effective in straightening the hair but can result in a reduction in hair strength and, in some cases, partial or total loss of hair through breakage. Some manufacturers market lithium and potassium hydroxide relaxers as “no lye” but, while this is technically true, these relaxers still rely on the soluble hydroxides of the inorganic potassium or lithium.
Most other “no lye” relaxers operate by obtaining hydroxide from a slightly soluble source such as Ca(OH)
2
. For example, the slightly soluble Ca(OH)
2
is mixed with guanidine carbonate to form the soluble but unstable source of hydroxide, guanidine hydroxide, and the insoluble calcium carbonate (CaCO
3
). The reaction is driven to completion by the precipitation of CaCO
3
and is in effect substituting one insoluble calcium salt for another. Because guanidine hydroxide is fundamentally unstable, the components are separated until the time of use.
Guanidine carbonate and calcium hydroxide, however, create a different set of problems. The insoluble byproduct, CaCO
3
, leaves a white residue or unattractive “whitening” or “ashing” that remains in the hair since divalent metals like calcium have a relatively good affinity to keratin. A decalcifying shampoo is subsequently needed to remove the ashing.
Thus, there is still a need for a process to relax keratin fibers that has the advantages of using an insoluble metal hydroxide, such as Ca(OH)
2
, but reduces or eliminates the problem of ashing caused by the insoluble byproduct, CaCO
3
.
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 a composition for lanthionizing keratin fibers comprising at least one multivalent metal hydroxide and at least one complexing agent effective for dissociating said at least one multivalent metal hydroxide in sufficient quantity to effect lanthionization of said keratin fibers. The at least one complexing agent may be chosen from, but is not limited to, organic acids and salts thereof and, in a preferred embodiment, is chosen from amino- and hydroxy-carboxylic acids, amino- and hydroxy- sulfonic acids, and amino- and hydroxy-phosphonic acids. However, the at least one complexing agent may not be only guanidine tartrate or only guanidine phosphate or only a mixture of guanidine tartrate and guanidine phosphate. The at least one multivalent metal hydroxide may be chosen from, but is not limited to, calcium hydroxide, barium hydroxide, magnesium hydroxide, aluminum hydroxide, cupric hydroxide, strontium hydroxide, molybdenum hydroxide, manganese hydroxide, zinc hydroxide, and cobalt hydroxide.
The present invention is also drawn to a method for lanthionizing keratin fibers to achieve relaxation of the keratin fibers by generating hydroxide ions in an ionizing solvent by adding to at least one multivalent metal hydroxide an activating composition wherein the activating composition comprises a complexing agent or a mixture of complexing agents effective for dissociating the at least one multivalent metal hydroxide in sufficient quantity to effect lanthionization of the keratin fibers; forming a composition containing the generated hydroxide ions; and applying the composition to keratin fibers for a period of time to lanthionize the keratin fibers. The lanthionization is terminated when the desired level of relaxation of the keratin fibers has been reached. The reverse process may also be used, i.e. the addition of the multivalent metal hydroxide to a composition comprising a complexing agent that is effective for dissociating at least one multivalent metal hydroxide in sufficient quantity to effect lanthionization of the keratin fibers.
Complexing agents for use in the methods of the invention may be chosen from, but are not limited to, organic acids and salts thereof and in a preferred embodiment are chosen from amino- and hydroxy-carboxylic acids, amino- and hydroxy-sulfonic acids, and amino- and hydroxy-phosphonic acids. However, the complexing agent(s) may not be only guani
Cannell David W.
Nguyen Nghi Van
Bennett Rachel M.
Finnegan Henderson Farabow Garrett & Dunner LLP
L'Oreal (S.A.)
Page Thurman K.
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