JP7508189B2 - Hair Strengthener - Google Patents

Description

The present invention relates to a hair strengthening agent. More specifically, the present invention relates to a hair strengthening agent that can strengthen the hair itself, rather than covering the hair with a film or the like. The present invention also relates to a hair strengthening agent composition and a hair strengthening treatment method that use the hair strengthening agent.

Hair has a mesh structure in which the polypeptide chains of keratin, the main component of hair, are connected by various side chain bonds (see Figure 1). It is thought that the main polypeptide chain of hair keratin, which normally has an α-helical structure (spiral shape), changes to β-keratin (zigzag shape) when pulled, causing the hair to elongate. Healthy hair will recover to its original length when the tensile stress is removed, but hair damaged by chemical treatments such as permanent wave processing or bleaching, or external stimuli such as ultraviolet rays, has low strength and tends to break easily.

It has been known for some time that protein derivatives such as keratin hydrolysates can be used to repair damaged hair. However, although keratin hydrolysates and the like have the effect of repairing deformation (peeling) of the cuticle on the hair surface, they do not have the effect of improving hair strength.

Patent Document 1 discloses a hair repair composition consisting of a cationized protein derivative and a neutral amino acid, and a hair strengthening agent containing a film-forming polymer compound in the composition. Patent Document 2 discloses a two-liquid hair strengthening agent consisting of Agent A, which is a buffer solution, and Agent B, which is an aqueous solution containing at least one selected from D,L-pyrrolidone carboxylic acid, amino acids, and glutathione, and hydroxypropyl cellulose, and describes that Agents A and B form a water-insoluble gummy substance on the hair to strengthen the hair. In other words, these conventional technologies are technologies that improve hair strength by covering the hair surface with a polymer coating or a gummy substance.

On the other hand, glyoxylic acid is used in hair treatments to suppress frizz and straighten curly hair. For example, Patent Document 3 discloses a method of applying an aqueous solution containing glyoxylic acid to hair, leaving it to stand, drying the hair with a hair dryer, and then straightening the hair with a hair straightening iron at a high temperature of about 200°C. Patent Document 4 discloses a hair treatment that contains guanidine salt and/or urea in addition to glyoxylic acid, and describes that it has an excellent hair lengthening (frizz suppression) effect. However, the function of glyoxylic acid in improving hair strength was completely unknown.

Japanese Patent Application Laid-Open No. 10-175824 JP 2010-189286 A Patent No. 5919267 Patent No. 5947340

The present invention was made in consideration of the above-mentioned conventional technology, and aims to provide a hair strengthening agent that can improve the strength of the hair itself.

As a result of intensive research aimed at solving the above problems, the inventors discovered for the first time that glyoxylic acid, which was previously used for hair lengthening (hair straightening), also has the function of improving the strength of the hair itself, which led to the completion of the present invention.

That is, the present invention provides a hair strengthening agent comprising glyoxylic acid, a hair strengthening agent composition containing the hair strengthening agent, and a hair strengthening treatment method using the hair strengthening agent.

The hair strengthening agent according to the present invention can improve the strength of keratin fibers by forming new bonds between the polypeptide chains that constitute keratin fibers such as hair.
In the present invention, "strengthening hair" or "improving hair strength" means improving the strength of the hair itself. "Strengthening" damaged hair also includes "repairing" damaged hair by improving its strength, which results in imparting "resilience" and "body" to the hair. Therefore, "strengthening hair" in the present invention is understood to include "repairing hair" and "imparting body and body to hair."

This is a schematic diagram illustrating the types of bonds present in hair. (Source: "New Cosmetics Studies," 2nd Edition, edited by Takeo Mitsui, Nanzando, 2001, p. 66) 1 is a graph showing the strength measurements of hair treated with the compositions of Example 1/Comparative Example 1. 1 is a graph showing the strength measurements of hair treated with the compositions of Example 2/Comparative Example 2.

The hair strengthening agent of the present invention comprises glyoxylic acid. Glyoxylic acid is a compound having a structure represented by the following formula (I).

As shown diagrammatically in Figure 1, various side chain bonds exist within hair, and the structure of hair is maintained by connecting the polypeptide chains of keratin through these bonds. In Figure 1, (salt bonds) represent mutual electrostatic bonds between (+) charged ammonium ions such as lysine and arginine residues and (-) charged carboxylate ions such as aspartic acid residues, (peptide bonds) represent dehydration bonds (-CONH-) between -COOH groups such as glutamic acid and -NH2 groups such as lysine residues, (cystine bonds) represent disulfide bonds that are unique to proteins containing sulfur (S) and are not found in other fibers, and (hydrogen bonds) are bonds between amide groups and adjacent carboxyl groups (see "New Cosmetics," 2nd Edition, edited by Mitsui Takeo, Nanzando, 2001, pp. 66-67).

For example, when forming permanent waves, the disulfide bonds (cystine bonds) in the side chain bonds are cut with a reducing agent, and new disulfide bonds are formed with an oxidizing agent while the hair is still waving. However, not all of the disulfide bonds that were once cut recombine, and the total number of side chain bonds in the hair decreases, which is thought to reduce the strength of the hair. It is also thought that some of the side chain bonds are cut when the hair is subjected to chemical treatments such as oxidative dyeing or bleaching, or when exposed to external stimuli such as ultraviolet light, resulting in a decrease in hair strength.

The present inventors have found for the first time that treating hair with glyoxylic acid can generate new bonds between keratin polypeptide chains via carboxymethylene groups, thereby improving hair strength. These new bonds are presumed to be cross-links formed between amino acid residues selected from lysine (Lys) residues, tyrosine (Tyr) residues, and arginine (Arg) residues that make up the keratin polypeptide chain (i.e., between Lys-Lys, between Lys-Arg, between Lys-Tyr, between Tyr-Tyr, between Arg-Tyr, or between Arg-Arg).

The present invention also relates to a hair strengthening composition containing the hair strengthening agent (i.e., glyoxylic acid).
The hair strengthening composition of the present invention is preferably in a form containing glyoxylic acid in an aqueous medium. The aqueous medium is water or a mixture of water and a water-soluble or hydrophilic medium (e.g., a lower alcohol having 3 or less carbon atoms, etc.).

The amount of glyoxylic acid in the hair strengthening composition of the present invention is not particularly limited, but is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, based on the total amount of the composition. If the amount is less than 1% by mass, it is difficult to obtain the effect of improving hair strength, and even if the amount exceeds 30% by mass, there is no further improvement in the effect and the composition becomes too acidic, which is not preferable.

The hair strengthening composition of the present invention is preferably adjusted to a pH of 3 or less, preferably 2.5 or less, more preferably 2 or less. The lower limit of the composition pH value is not particularly limited, but it is usually adjusted to 1.0 or more. The pH of the composition can be appropriately adjusted by neutralizing the acidity of glyoxylic acid. Examples of neutralizing agents (pH adjusters) include, but are not limited to, inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as triethanolamine, isopropanolamine, and basic amino acids.

In addition to glyoxylic acid and an optional neutralizing agent, the hair strengthening composition of the present invention may contain other optional components that are commonly used in cosmetics and pharmaceuticals for hair treatment, within the range that does not impair the effects of the present invention. Such optional components may include, for example, cationic polymers, amino acids, peptides, proteins, sequestering agents, oils, powder components, surfactants, thickeners, fragrances, colorants, etc.

The formulation of the hair strengthening composition of the present invention is not particularly limited as long as it satisfactorily exerts the desired effect, but it may be in the form of, for example, a liquid, emulsion, gel, foam, cream, etc.

The present invention also provides a hair strengthening treatment method using the hair strengthening agent composition.
The hair strengthening treatment method of the present invention includes the steps of (1) applying the above-mentioned hair strengthening agent or hair strengthening agent composition to hair, (2) leaving the hair in the applied state, (3) rinsing the hair with water, (4) drying the hair, and (5) optionally treating the hair with a hair styling iron. Such a hair strengthening treatment method is suitable for implementation in a hair salon or the like.

(1) Application step The hair strengthening agent composition of the present invention can be applied to dry hair before shampooing. However, since the hair strengthening agent (glyoxylic acid) easily penetrates the hair, it is preferable to apply it to wet care where the hair has been washed with shampoo and then dried, or to towel-dried hair where the moisture has been removed with a towel.

(2) Leaving Step After application of the hair strengthening agent composition, it is left at room temperature (about 25° C.) for 10 to 30 minutes, more preferably 15 to 20 minutes, to allow the hair strengthening agent to act on the hair. If the leaving time is less than 10 minutes, the hair cannot be sufficiently strengthened, while if the leaving time is more than 30 minutes, further improvement in the hair strengthening effect commensurate with the leaving time cannot be expected.

(3) Water-Rinse Step The hair is rinsed with water or lukewarm water to wash away the hair strengthening composition from the hair. By washing away the hair strengthening composition from the hair, the hair can be easily dried and handled thereafter.

(4) Drying Step After rinsing with water, the water is wiped off with a towel and then dried with a hair dryer.

(5) Ironing process (optional)
The hair dried in (4) above already has improved strength, but optionally, a step of straightening the hair while applying mechanical force and heat to the hair with a hair styling iron heated to 140 to 200°C, preferably about 180°C, may be carried out.

According to the hair strengthening treatment method of the present invention, the action of glyoxylic acid forms new cross-links between lysine, tyrosine, and arginine residues in the polypeptide chains that make up keratin, significantly improving the strength of hair.

Although glyoxylic acid has been described in detail above, the above content is not limited to glyoxylic acid, and the above-mentioned effects can be obtained similarly with pyruvic acid.

The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to the following examples. In addition, the blending amounts in the following examples are expressed as mass % unless otherwise specified.

Hair treatment compositions having the compositions shown in Table 1 below were prepared. Example 1 is a hair strengthening composition according to the present invention, and Comparative Example 1 is a treatment composition containing hydrolyzed protein that has traditionally been used to repair damaged hair.

A healthy bundle of hair was bleached once using a bleaching agent (PRIMIENCE CL13, manufactured by Shiseido Professional Co., Ltd.). Then, it was straightened twice using a hair straightener (Crystalizing Straight EX, manufactured by Shiseido Professional Co., Ltd.).

The compositions of Example 1 and Comparative Example 1 were applied to the same amount of damaged hair bundles prepared as described above, left for 15 minutes, rinsed with water, and dried with a hair dryer.

One end of the treated hair bundle was fixed and a tensile stress was applied in the vertical direction. The stress value at which the hair broke (stress at break) is shown in Figure 2 in comparison with untreated damaged hair.
As is clear from the graph in Figure 2, when hair damaged and weakened by chemical treatment was treated with the composition of Example 1 according to the present invention, the strength was significantly improved, and when the number of treatment cycles was increased to 3, the strength was further increased. Although a certain degree of strength improvement was observed with Comparative Example 1, which is a conventional repair agent, the degree was not as high as that of the present invention, and no further improvement in strength was observed even with an increase in the number of treatment cycles.

Traditionally, hair straightening (straight perm) was recognized as a treatment that damaged hair, just like permanent wave formation. However, glyoxylic acid, which is known to have hair straightening properties, does not damage hair, but rather has the effect of improving hair strength. It has also been confirmed that its hair strengthening (damage repair) effect is stronger than that of repair agents that have been widely used in the past.

Next, hair treatment compositions having the compositions shown in Table 2 below were prepared. Example 2 is a hair strengthening agent composition according to the present invention, and Comparative Example 2 is a commonly used permanent treatment agent (reducing agent) composition.

The compositions of Example 2 and Comparative Example 2 were applied to healthy hair bundles (equal amounts), left for 15 minutes, rinsed with water, dried with a hair dryer, and then ironed three times using a hair styling iron set at 180°C by the through method.
The above treatment cycle was carried out either once or three times.

The graph in Figure 3 shows the relationship between the hair elongation rate (horizontal axis) and stress (vertical axis) when one end of the treated hair bundle is fixed and a tensile stress is applied in the vertical direction. The stress value required for the hair to extend in length by 3% and the stress value when the hair breaks are shown in Table 3 below.

As is clear from the results shown in Figure 3 and Table 3, hair treated with the composition of Comparative Example 2, which contains thioglycolic acid, a reducing agent used in permanent wave treatment, had reduced strength compared to untreated hair, and when the number of treatment cycles was increased to three, the strength was further reduced. In contrast, when treated with the composition of Example 2, which contains glyoxylic acid, the strength was clearly improved compared to untreated hair, and when the number of treatment cycles was increased to three, the strength was further increased.

Claims (3)

A hair strengthening composition for improving the tensile strength of hair, which comprises only glyoxylic acid , stearyltrimethylammonium chloride , a neutralizing agent and water . 2. The hair strengthening composition of claim 1 , wherein the pH of the composition is in the range of 1.0 to 3.0. (1) Applying the hair strengthening composition according to claim 1 to hair,
(2) Leave the applied product on the hair,
(3) Rinse the hair with water;
(4) A hair strengthening treatment method for improving the tensile strength of hair , comprising a step of drying the hair.