Drug – bio-affecting and body treating compositions – Live hair or scalp treating compositions – Permanent waving or straightening
Reexamination Certificate
2002-06-28
2004-10-05
Venkat, Jyothsna (Department: 1615)
Drug, bio-affecting and body treating compositions
Live hair or scalp treating compositions
Permanent waving or straightening
C424S070100
Reexamination Certificate
active
06800277
ABSTRACT:
The present invention relates to methods for lanthionizing keratin fibers using a combination of at least one carbonate compound, at least one chelating acid, and at least one hydroxide compound. The at least one chelating acid can react with the at least one carbonate compound to effect generation of carbonic acid gas and a chelating compound. In one embodiment, the process of lanthionizing keratin fibers may result in relaxed, including straightened, hair. The invention is also directed to multicomponent kits for relaxing, including straightening, hair comprising at least one carbonate compound, at least one chelating acid, and at least one hydroxide compound.
Straightening or relaxing the curls of very curly hair may increase the manageability and the ease of styling such hair. In today's market, there is an increasing demand for hair care products referred to as “hair relaxers” which can relax or straighten naturally curly or kinky hair. Hair relaxers may either be applied in a hair salon by a professional or in the home by the individual consumer.
Hair fiber is a keratinous material which is comprised of proteins. Many of the polypeptides in hair fibers are bonded together by disulfide bonds (—S—S—). A disulfide bond may be formed from the reaction of the two sulfhydryl groups (—SH) one on each of two cysteine residues which results in the formation of a cystine residue. While there may be other types of bonds between the polypeptides in hair fibers, such as ionic bonds, the permanent curling and the shape of the hair is essentially dependent on the disulfide bonds of cystine residues.
Generally, hair relaxing processes are chemical processes which may alter the aforementioned disulfide bonds between polypeptides in hair fibers and may form lanthionine residues [S[CH
2
CH(NH—)(CO—)]
2
]. Thus, the term “lanthionizing” is used when one skilled in the art refers to the relaxing, including straightening, of keratin fibers by hydroxide ions.
For example, hair fibers may be relaxed or straightened by disrupting the disulfide bonds of the hair fibers with an alkaline reducing agent. The chemical disruption of disulfide bonds with such an agent is generally combined with mechanical straightening of the hair, such as combing, and straightening generally occurs due to changes in the relative positions of neighboring polypeptide chains within the hair fiber.
This reaction is generally terminated by rinsing and/or application of a neutralizing composition.
The reaction with the alkaline agent is normally initiated by available hydroxide ions. As used herein, “available hydroxide ions” are hydroxide ions which are available for lanthionization. Not to be limited by theory, there are two reaction sequences that are predominantly used in the art to explain the disruption of the disulfide bonds in hair fibers by available hydroxide ions. Both of these reaction sequences result in lanthionine residue formation. One reaction sequence comprises at least one bimolecular nucleophilic substitution reaction wherein an available hydroxide ion directly attacks the disulfide linkage of a cystine residue. The result is the formation of lanthionine residues and HOS
−
. See Zviak, C.,
The Science of Hair Care,
185-186 (1986). The second reaction sequence comprises at least one &bgr;-elimination reaction initiated by the nucleophilic attack of an available hydroxide ion on a hydrogen atom bonded to a carbon atom that is in the &bgr;-position with respect to the disulfide bond of a cystine residue. See Zviak. The result is the formation of a dehydroalanine residue. The dehydroalanine residue then reacts with either the thiol group of a cysteine residue or the amino group of an alanine residue to form a lanthionine residue or a lysinoalanine residue, respectively. These stable irreversible crosslinks in the treated hair make subsequent chemical re-linking of the polypeptides unnecessary. Thus, the only step that may be required following a straightening process using such hydroxide-containing alkaline agents is the removal of any excess alkaline solution to avoid and minimize damage to the hair protein or skin. If such a step is required, an acidic shampoo may be used to neutralize residual alkali and remove it from the hair and scalp.
Hydroxide-containing alkaline agents also have other advantages. For example, alkaline agents, such as guanidine hydroxide, do not have a highly objectionable odor or cause such an odor on treating the hair. Further, hydroxide-based straighteners generally have relatively fast processing times and good relaxation of naturally curly or kinky hair. Additionally, the achieved relaxing effect is more permanent; i.e., less likely to revert to a curly state after shampooing and wearing than is hair relaxed with some other relaxers.
Despite these advantages, certain hydroxide-containing alkaline agents may have disadvantages. These disadvantages may be heightened when the hydroxide-containing alkaline agent is sodium hydroxide. Specifically, the causticity of sodium hydroxide can adversely affect the condition of the hair, for example, leaving it in a brittle state and harsh to the touch. Additionally, prolonged or unnecessary exposure of hair to such a strong alkali can weaken, break and dissolve the hair. In some instances, such a strong alkali can discolor the natural color of the hair. For example, the tone of natural brown hair may be reddened and natural white or grey hair may be yellowed. Further, the natural sheen of the hair may be delustered.
Most frequently, commercial relaxing compositions are in the form of gels or emulsions that contain varying proportions of strong water-soluble bases, such as sodium hydroxide (NaOH), or of compositions that contain slightly-soluble metal hydroxides, such as calcium hydroxide (Ca(OH)
2
), which can be converted in situ to soluble bases, such as guanidine hydroxide. Traditionally, the two main hair relaxers used in the hair care industry for generating hydroxide ions are referred to as “lye” (lye=sodium hydroxide) relaxers and “no lye” relaxers.
The “lye” relaxers generally comprise sodium hydroxide in a concentration ranging from 1.5% to 2.5% by weight relative to the total weight of the composition (0.38M-0.63M) depending on the carrier used, the condition of the hair fibers and the desired length of time for the relaxation process.
While “no lye” relaxers may not contain lye, they may nonetheless rely on the soluble hydroxides of inorganic metals, such as potassium hydroxide and lithium hydroxide. Other “no lye” relaxers may use hydroxide ions obtained, for example, from a slightly-soluble source, such as Ca(OH)
2
. For example, the slightly soluble Ca(OH)
2
may be mixed with guanidine carbonate to form guanidine hydroxide, a soluble but unstable source of hydroxide, and insoluble calcium carbonate (CaCO
3
). This reaction is driven to completion by the precipitation of CaCO
3
and is, in effect, substituting one insoluble calcium salt for a slightly soluble calcium salt. Because guanidine hydroxide is unstable, the components are stored separately until the time of their use.
In commercial products based on guanidine hydroxide, the concentration of guanidine carbonate used is generally at least 5.8% by weight relative to the total weight of the final mixture. Significantly, it is known that relaxers derived from guanidinium hydroxide are inherently less irritating to the skin and scalp than those deriving from alkali metal hydroxides. See U.S. Pat. No. 5,849,277, the disclosure of which is incorporated herein by reference.
Although generally gentler on the hair, guanidine carbonate and calcium hydroxide may create a different set of problems. The insoluble byproduct, CaCO
3
, can leave a white residue or unattractive “whitening” or “ashing.” This residue remains in the hair since divalent metals such as calcium have a relatively good affinity for keratin. A decalcifying shampoo may be subsequently needed to remove the ashing.
This ashing may be especially problematic when using strong
Cannell David W.
Nguyen Nghi Van
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
L'Oreal (S.A.)
Venkat Jyothsna
LandOfFree
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