Oxidative hair dye

Abstract

To provide an oxidation hair dye capable of dyeing hair in a dark color tone close to black hair without large color variation while reducing a load on the hair.SOLUTION: A first agent containing an oxidation dye and an alkali agent, and a second agent containing an oxidizing agent, wherein the first agent and the second agent are mixed at a weight ratio of 1:1 to 1:3, the oxidation dye is contained in an amount of 0.66 to 7.0% by weight based on the total weight of the first agent and the second agent, p-methylaminophenol and 2,2 ' - [(4-aminophenyl) imino] bisethanol are used as precursors, resorcin, m-aminophenol, and 5-amino-o-cresol are used as couplers, and resorcin is contained in an amount larger than the total amount of m-aminophenol and 5-amino-o-cresol in terms of weight ratio; The hair dye composition contains p-methylaminophenol and / or its salt in an amount larger than that of p-methylaminophenol and / or its salt, and is used for dyeing hair from which melanin pigment is removed or white hair into a dark color tone close to black hair.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oxidation hair dye suitable for use in dyeing hair to a dark color tone close to black (lightness of 3.5 or less, chroma of 3 or less in the JIS color catalog (JIS Z 8102)). [Background technology]

[0002] In Japan, when people are faced with occasions such as weddings, funerals, or job hunting, and want to darken hair that has become lighter due to bleaching, or to color gray hair to make it less noticeable, they often dye their hair a dark color close to the characteristic black hair of Japanese people (a color that is relatively close to black hair, such as black or dark brown). For this type of coloring, oxidation hair dyes (hair colors that develop color through the oxidative polymerization of oxidation dyes) are generally used.

[0003] Oxidative hair dyes are dyes that penetrate the hair with an oxidative dye and then oxidatively polymerize the oxidative dye with an oxidizing agent to produce color. Two-part oxidative hair dyes are widely used, consisting of a first part containing an oxidative dye and an alkaline agent, and a second part containing hydrogen peroxide (an example of an oxidizing agent). The alkaline agent is added to the first part to swell the hair and promote penetration of the oxidative dye into the hair, as well as to activate the hydrogen peroxide.

[0004] Oxidation dyes contain a precursor (dye intermediate) and a coupler (toning agent). When oxidized by an oxidizing agent, the precursor polymerizes and develops a color. When oxidized alone, the coupler hardly develops a color, but when oxidized together with the precursor, a color different from the color developed by the precursor alone is developed. The combination of precursor and coupler is determined depending on the desired color. For example, when dyeing hair a blue color, only precursors and couplers that develop a blue color can be used, and precursors and couplers that develop colors other than blue can be omitted. In this way, depending on the desired color, only a combination of precursors and couplers that develop a single color can be used. However, when developing a dark color close to black hair, an oxidation dye is produced by combining precursors and couplers that develop multiple colors, such as yellow, brown, purple, and blue. In general, the color development tends to be more unstable when a combination of a precursor and a coupler that develops a color in a plurality of color systems is used compared to when only a combination of a precursor and a coupler that develops a color in a single color system is used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-057165 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-088891 Summary of the Invention [Problem to be solved by the invention]

[0006] Oxidative dyes with strong dyeing properties are used when trying to achieve stable dyeing power that is not affected by differences in hair quality due to gender, age, etc. Traditionally, when creating an oxidative dye that can produce dark colors close to black hair and has strong dyeing properties, paraphenylenediamine or toluene-2,5-diamine have been selected as precursors, and in these cases, resorcinol or meta-aminophenol are essential couplers.

[0007] Here, when paraphenylenediamine or toluene-2,5-diamine is selected as the precursor, the resorcinol coupler (in this case, a coupler that produces a yellowish color) requires a certain level of pH and alkalinity to produce color, and the color becomes significantly weaker as the pH value or alkalinity decreases, resulting in an imbalance in the color produced by an oxidation hair dye containing this compound.

[0008] Furthermore, when paraphenylenediamine or toluene-2,5-diamine is selected as the precursor, meta-aminophenol as the coupler (in this case, a coupler that produces a brownish color) takes a certain amount of time to develop color. Therefore, if the time is shortened, the brownish color will become lighter, and hair dyed with an oxidation hair dye containing this compound will not be as dark as black hair.

[0009] Incidentally, when it comes to hair that has been repeatedly colored, the new growth (mainly the part near the roots of the hair) that has not been colored tends to be more difficult to dye than the previously colored part (mainly the part from the middle to the ends of the hair). Oxidative hair dyes that have enhanced dyeing power to thoroughly dye the newly growing part are excessively strong for the previously colored part and can also cause extra damage to the hair. The longer the hair, the greater the volume of the previously colored part in the overall hair, which increases the burden on the entire hair.

[0010] For this reason, beauty salons sometimes use different treatment methods for dyed and newly grown hair. Specifically, with oxidative hair dyes consisting of a first and second agent, the mixing ratio of the two agents is generally 1:1, which is designed to achieve a sufficient dyeing effect. Therefore, an oxidative hair dye with this mixing ratio (1:1) is applied to newly grown hair, and an oxidative hair dye with a first and second agent mixing ratio of 1:2-3 (1:2-1:3) is applied to dyed hair. This method reduces the amount of alkali, thereby reducing the burden on dyed hair. However, with conventional oxidative hair dyes that use resorcinol as a coupler, the color development of the resorcinol significantly weakens as the amount of alkali decreases, making it difficult to achieve a dark color tone similar to black hair.

[0011] Another approach is to apply an oxidative hair dye with a 1:1 ratio to the new hair growth, and then, after a certain time, apply the same agent to the already dyed hair. In other words, by shortening the contact time of the oxidative hair dye with the already dyed hair, the burden on the hair can be reduced to some extent, but with the above-mentioned conventional oxidative hair dyes that use meta-aminophenol as a coupler, the color development of the meta-aminophenol becomes insufficient as the leaving time is shortened, and it is still not possible to develop a dark color tone close to black hair.

[0012] Patent documents 1 and 2 report oxidative hair dyes for dyeing gray hair, but neither of them improves the unstable color development that occurs when taking into consideration the reduction of burden on damaged areas (already dyed areas).

[0013] As a result of research into achieving both dyeability and reduced burden on hair, the inventors have discovered that by using paramethylaminophenol and 2,2'-[(4-aminophenyl)imino]bisethanol, which have traditionally been used as auxiliary agents, as precursors instead of paraphenylenediamine or toluene-2,5-diamine, it is possible to dye hair without significant color variation to dark shades close to black hair, such as the desired dark brown or a similar black, even while reducing the burden on the hair (already dyed areas) by selecting resorcinol or meta-aminophenol as couplers and changing the mixing ratio of the first and second agents to 1:2-3.

[0014] The present invention has been made in consideration of the above matters, and its object is to provide an oxidation hair dye that can dye hair in a dark color tone close to black without significant color variation while reducing the burden on hair. [Means for solving the problem]

[0015] In order to achieve the above object, the oxidation hair dye of the present invention is an oxidation hair dye that uses a mixture of a first agent containing an oxidation dye and an alkaline agent and a second agent containing an oxidizing agent, the first agent and the second agent being mixed in a weight ratio of 1:1 to 1:3, the oxidation dye being contained in an amount of 0.66 to 7.0% by weight of the total mixture of the first agent and the second agent, paramethylaminophenol and / or a salt thereof, and 2,2'-[(4-aminophenyl)imino]bisethanol and / or a salt thereof as precursors, and resorcinol, meta-aminophenol, and 5-aminoorthocresol as couplers, the weight ratio of resorcinol being greater than the total of meta-aminophenol and 5-aminoorthocresol, and greater than paramethylaminophenol and / or a salt thereof, and is used to dye hair that has lost its melanin pigment or gray hair to a dark color tone close to black hair (Claim 1).

[0016] In the above oxidation hair dye, para-aminophenol may also be used as a precursor (claim 2).

[0017] In the oxidation hair dye, one or more of ammonia and monoethanolamine may be blended as the alkaline agent (claim 3).

[0018] The above-mentioned oxidation hair dye may not contain paraphenylenediamine, toluene-2,5-diamine, or salts thereof as precursors (claim 4).

[0019] The above-mentioned oxidative hair dye may be used to dye hair from which melanin pigment has been removed or gray hair to a dark color close to black hair (claim 5). [Effects of the Invention]

[0020] The present invention provides an oxidation hair dye that reduces the burden on hair and allows for dyeing hair in dark shades close to black without significant color variation. DETAILED DESCRIPTION OF THE INVENTION

[0021] An embodiment of the present invention will be described below.

[0022] The oxidative hair dye of the present invention is used to dye hair that has lost its melanin pigment or gray hair to a dark color tone close to black hair (lightness of 3.5 or less, saturation of 3 or less in the JIS color name book). It consists of a first agent containing an oxidative dye and an alkaline agent, and a second agent containing an oxidizing agent. For example, the first agent and the second agent are mixed immediately before use and then applied to the hair.

[0023] Furthermore, in order to reduce the burden on damaged hair areas when applied (sprayed) to those areas without impairing the necessary dyeability, the first and second agents of the present invention can be used in various ways, such as reducing the alkaline content in the mixture of the first and second agents by changing the mixing ratio (weight ratio) of the first and second agents from 1:1 to 1:2-3; adding an acid agent to the second agent to partially neutralize the first and second agents when they are mixed, adjusting the pH value of the system from alkaline to near neutral when mixed; and reducing the usual leaving time of 30 minutes to half (15 minutes) to reduce the contact time of the mixture.

[0024] The couplers to be blended with the oxidation dye of the first agent are resorcinol, meta-aminophenol, and 5-amino-orthocresol, and 2,6-diaminopyridine, 2,4-diaminophenoxyethanol hydrochloride, 5-(2-hydroxyethylamino)-2-methylphenol, and α-naphthol may also be used in combination within the blending range, with no particular limitation, as long as the effects of the present invention are achieved.

[0025] Furthermore, a direct dye such as paranitroorthophenylenediamine may be blended with the oxidation dye of the first agent.

[0026] The precursors to be incorporated into the oxidation dye of the first agent are para-methylaminophenol and / or its salts and 2,2'-[(4-aminophenyl)imino]bisethanol and / or its salts. Para-aminophenol may be used in combination within an unrestricted range as long as the effects of the present invention are achieved. As mentioned above, when resorcinol and meta-aminophenol are used as couplers, selecting para-phenylenediamine or toluene-2,5-diamine as the precursor may result in the desired color not being achieved. Therefore, para-phenylenediamine, toluene-2,5-diamine, and their salts are not included as precursors. Furthermore, because resorcinol is effective in dyeing hair that has lost its melanin pigment or gray hair to a dark color close to black, it is preferable to contain more resorcinol by weight than the combined total of meta-aminophenol and 5-aminoorthocresol, and more resorcinol than para-methylaminophenol and / or its salts.

[0027] Resorcinol (coupler) produces a yellow color when combined with paramethylaminophenol (precursor) and a red color when combined with 2,2'-[(4-aminophenyl)imino]bisethanol (precursor). Metaaminophenol (coupler) produces a yellow color when combined with paramethylaminophenol (precursor) and a blue color when combined with 2,2'-[(4-aminophenyl)imino]bisethanol (precursor). 5-aminoorthocresol (coupler) produces a yellow color when combined with paramethylaminophenol (precursor) and a purple color when combined with 2,2'-[(4-aminophenyl)imino]bisethanol (precursor). Furthermore, by combining paramethylaminophenol and / or its salts and 2,2'-[(4-aminophenyl)imino]bisethanol and / or its salts as precursors, and resorcinol, metaaminophenol, and 5-aminoorthocresol as couplers, the desired dark color tone close to black hair can basically be achieved.

[0028] On the other hand, para-aminophenol (precursor) develops yellow, orange, and orange colors in combination with resorcinol (coupler), meta-aminophenol (coupler), and 5-aminoorthocresol (coupler), respectively. Using this facilitates color development to dark browns and other colors with a dark tone close to the desired black hair color. However, instead of using para-aminophenol (precursor), it is possible to use, for example, para-nitroorthophenylenediamine, a direct dye that develops orange on its own. In this way, if the desired hair color cannot be achieved using only the combination of precursor and coupler, a color that approximates the desired hair color (a complementary color if the desired hair color is black) or a direct dye that develops a similar color may be used.

[0029] The content of the oxidation dye is preferably 0.1 to 7.0% by weight, and particularly preferably 0.66 to 2.63% by weight, based on the total weight of the first and second agents combined. If the content of the oxidation dye is less than 0.1% by weight, it is difficult to obtain sufficient hair dyeing power to achieve the object of the present invention, and even if it exceeds 7.0% by weight, it is difficult to obtain any greater hair dyeing power.

[0030] From the viewpoint of dyeing lightened hair or gray hair due to bleaching of melanin pigment to a dark color tone close to black hair, the total amount of the precursors, paramethylaminophenol and / or its salt, 2,2'-[(4-aminophenyl)imino]bisethanol and / or its salt, and the coupler, resorcinol, metaaminophenol, and 5-aminoorthocresol, is preferably 70% by weight or more, more preferably 80% by weight or more, of the total amount of the oxidation dye.

[0031] Furthermore, the blending ratio of paramethylaminophenol and / or its salt (A) to 2,2'-[(4-aminophenyl)imino]bisethanol and / or its salt (B) is not particularly limited as long as the effects of the present invention are exhibited. However, from the viewpoint of dyeing lightened hair or gray hair due to bleaching of melanin pigment to a dark color tone close to black hair, the weight % ratio of A:B is preferably 1:4 to 1:13, more preferably 1:7 to 1:11.

[0032] Furthermore, the blending ratio of all precursors (C) to all couplers (D) is not particularly limited as long as the effects of the present invention are exhibited, but from the viewpoint of dyeing lightened hair due to bleaching of melanin pigments or gray hair to a dark color tone close to black hair, the weight % ratio of C:D is preferably 4:1 to 1:3, more preferably 3:1 to 1:2.

[0033] The alkaline agent to be incorporated into the first agent is not particularly limited as long as it can be incorporated into the first agent, but from the viewpoint of dyeing light hair, particularly gray hair, to a dark color tone close to black hair, it is preferable to use ammonia, monoethanolamine, ammonium bicarbonate, etc.

[0034] The amount of alkaline agent in the first agent is not particularly limited as long as it swells the hair to be dyed and promotes the penetration of the oxidative dye into the hair, but from the viewpoint of hair dyeability, the alkalinity is preferably 1 mL or more, and more preferably 3 mL or more. The alkalinity refers to the number of mL of 0.1 mol / L hydrochloric acid solution required to neutralize 1 g of sample.

[0035] Furthermore, from the viewpoint of irritation when the oxidative hair dye adheres to the scalp during hair dyeing, the alkalinity is preferably 15 mL or less, more preferably 12 mL or less. For these reasons, the content of the alkaline agent in the first agent is 1 to 15 mL, more preferably 3 to 12 mL, in terms of alkalinity.

[0036] On the other hand, the second agent contains an oxidizing agent as an essential component in order to achieve the effects of the present invention. Hydrogen peroxide can be used as the oxidizing agent.

[0037] The content of the oxidizing agent (hydrogen peroxide) in the second agent is not particularly limited as long as it exhibits the effects of the present invention. From the viewpoint of dyeability, the content of the oxidizing agent (hydrogen peroxide) is preferably 0.5 to 5.0 wt %, and particularly preferably 2 to 3.5 wt %, based on the total weight of the first and second agents combined. If the content is less than 0.5 wt %, it is difficult to obtain sufficient hair dyeing power to achieve the object of the present invention, and even if it exceeds 5.0 wt %, it is difficult to obtain further hair dyeing power.

[0038] From the viewpoint of reducing the burden on damaged hair (previously dyed areas), in particular, an acid (acidic substance) may be blended into the second agent within the scope that achieves the effects of the present invention. Specific examples of acids include phosphoric acid, glyoxylic acid, citric acid, malic acid, maleic acid, pyrrolidonecarboxylic acid, tartaric acid, succinic acid, levulinic acid, lactic acid, malonic acid, glycolic acid, glutaric acid, adipic acid, and fumaric acid, and these may be used alone or in combination of two or more.

[0039] The acid content is preferably in the range of 0.1 to 7% by weight, and more preferably in the range of 0.5 to 5% by weight. This is because, if the acid content is below 0.1% by weight, it becomes difficult to achieve the effect of lowering the alkalinity of the first agent (partially neutralizing the alkaline agent), and if the mixing ratio of the second agent is increased to increase the amount of neutralization, the content of the oxidation dye in the mixed solution decreases, and the desired dyeing cannot be achieved. Furthermore, if the acid content exceeds 7% by weight, the alkalinity of the system when the first and second agents are mixed decreases drastically, making it difficult to achieve stable color development.

[0040] The first and second agents according to the present invention can be used in various dosage forms such as liquid, gel, cream, etc., and are used by mixing the first and second agents. The mixing ratio of the first and second agents is usually about 1:1 to 1:3 by weight.

[0041] The pH value of the system when the first and second agents are mixed is not particularly limited as long as it exerts the effects of the present invention, but from the viewpoint of dyeing hair that has become light due to bleaching of melanin pigment or gray hair to a dark color tone close to black hair, a pH of 6 to 11 is preferred, and a pH of 7 to 10 is more preferred.

[0042] The present invention will be explained below by showing formulation examples, and by listing formulation examples that satisfy the requirements of the present invention and formulation examples that do not satisfy the requirements depending on the application method. The first agent formulation examples shown in Table 1 can be broadly classified into conventional formulation example A, which uses toluene-2,5-diamine or a salt thereof as a precursor, and improved formulation example B, which uses paramethylaminophenol and / or a salt thereof and 2,2'-[(4-aminophenyl)imino]bisethanol and / or a salt thereof as precursors. Formulation examples A1 to A3 belonging to conventional formulation example A have the same ingredients but different amounts of precursors, couplers, etc., while formulation examples B1 to B6 belonging to improved formulation example B have the same ingredients but different amounts of precursors, couplers, etc. Note that the amounts shown in the formulation examples are expressed in weight percent unless otherwise specified. In addition, alkalinity as an index value refers to the number of mL of 0.1 mol / L hydrochloric acid solution required to neutralize 1 g of sample, and acidity refers to the number of mL of 0.1 mol / L sodium hydroxide solution required to neutralize 1 g of sample.

[0043] [Table 1]

[0044] [Table 2]

[0045] [Table 3]

[0046] [Table 4]

[0047] The pH values ​​in Tables 1 to 4 were measured using a pH meter (F-52, manufactured by Horiba, Ltd.), and the alkalinity and acidity shown in Tables 1 and 2 were measured using an automatic potentiometric titrator (AT-710, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The alkalinity values ​​in Tables 3 and 4 are theoretical values ​​calculated from the measurements in Tables 1 and 2, since the alkalinity is consumed when the first and second parts are mixed.

[0048] As shown in Table 1, first agent prescription examples A1 to A3 were formulated to have the same pH value and alkalinity, and therefore the pH values ​​and alkalinity of each mixing example shown in Table 3 are common results when these prescription examples A1 to A3 are used. Similarly, as shown in Table 1, first agent prescription examples B1 to B6 were formulated to have the same pH value and alkalinity, and therefore the pH values ​​and alkalinity of each mixing example shown in Table 4 are common results when these prescription examples B1 to B6 are used.

[0049] Furthermore, Mixing Examples 1 to 6 in Table 3 all contain Agent 1 A, while Mixing Examples 1 to 6 in Table 4 contain Agent 1 B instead of Agent 1 A, with the mixing ratio of the first agents (Agent 1 A, B) being the same between corresponding Mixing Examples (for example, in both Mixing Example 1 in Table 3 and Mixing Example 1 in Table 4, the mixing ratio of Agent 1 to Agent 2 A is 1:1). In this specification, whether each Mixing Example contains Agent 1 A or Agent 1 B can be distinguished by clearly indicating in the table title whether Agent 1 A or Agent 1 B is included.

[0050] From Table 3, it can be seen that the pH values ​​of Mixing Examples 2 and 3 are almost the same as that of Mixing Example 1, but the alkalinity is lower, which is thought to reduce the burden on hair. In addition, the pH values ​​and alkalinity of Mixing Examples 4, 5, and 6 are lower than Mixing Examples 1, 2, and 3, respectively, which is thought to further reduce the burden on hair.

[0051] As can be seen from Table 4, the pH values ​​of Blending Examples 2 and 3 are almost the same as Blending Example 1, but the alkalinity is lower, which is thought to reduce the burden on hair. Furthermore, the pH values ​​and alkalinity of Blending Examples 4, 5, and 6 are lower than those of Blending Examples 1, 2, and 3, respectively, which is thought to further reduce the burden on hair, and the oxidative hair dye of the present invention can be used in a way that reduces the burden on hair.

[0052] Next, for each of the nine types of first agents shown in Table 1, a total of 54 types (9 types x 6 examples) of agents were prepared by changing the mixing ratio with second agents A and B as shown in Tables 3 and 4, and four types of hair strands with different brightnesses were dyed (see [Hair Dyeing Method] below), and the ability of each agent as a hair dye was compared based on its dyeing ability. [Hair dyeing method] Hair bundles (yak hair (level 20), 15-level human hair, 10-level human hair, and 5-level human hair) manufactured by George Matai Japan Co., Ltd., weighing 1.2 g per strand and measuring 120 mm each, were used. A mixture of the first agent listed in Table 1 and the second agent listed in Table 2, prepared in the ratios listed in Tables 3 and 4, was applied in an amount of 2 g per strand and then left at 30°C for 15 or 30 minutes. The hair was then rinsed with warm water, shampooed, and treated with a conditioner to complete the dyeing process. The 15-level, 10-level, and 5-level human hairs were human hairs with brightness levels of 15, 10, and 5, respectively, measured on our tone scale (a level scale created by Tamari Chemical Co., Ltd.), while the brightness of the yak hair was 20.

[0053] Our tone scale uses 15 brightness levels, starting with level 4 (scale number 4), which represents the darkness of Japanese black hair, and 20 levels for the brightness of white. Levels 3 represent darker shades than level 4, and level 2 represents even darker shades. In recent years, bluish-black tones darker than human black hair have become popular in black design. Therefore, we have prepared levels 2 and 3 for our tone scale to determine shades darker than human black hair. Below are the results of a comparison of each scale number (levels 2 through 20) on our tone scale (a nylon scale) to determine which color names in the JIS Color Name Book (based on JIS Z 8102) correspond (match or most closely resemble) to the corresponding color names.

[0054] [Table 5]

[0055] [Test to confirm dark hair color close to black] For each hair strand that had been dyed as described above, it was confirmed using the JIS color book whether it had been dyed to a dark color tone close to black (lightness of 3.5 or less, saturation of 3 or less in the JIS color book). ○: According to the JIS color name book, "brightness 3.5 or less, saturation 3 or less." ×: The above conditions are not met.

[0056] [Table 6]

[0057] [Table 7]

[0058] [Table 8]

[0059] Table 9

[0060] Table 10

[0061] Table 11

[0062] Table 12

[0063] Table 13

[0064] Table 14

[0065] Table 6 shows that when an oxidative hair dye formulation using First Agent Formulation Example A1 is used, it tends to be more difficult to achieve a darker shade (lightness of 3.5 or less, saturation of 3 or less in the JIS color guide) close to black when the hair brightness is lighter, the dye concentration (the concentration of oxidative dye in the total mixture of First Agent and Second Agent) is lower, or the time required for dyeing is shortened (reducing the time from the usual 30 minutes after application to 15 minutes). First Agent Formulation Examples A2 and A3, as shown in Table 1, are formulations in which the amount of dye in First Agent Formulation Example A1 is gradually increased. Tables 7 and 8 show that the formulations of oxidative hair dyes using these formulations tend to more easily achieve the desired effect, but did not produce satisfactory results. On the other hand, Tables 9 to 14 show that when the oxidative hair dye formulations using the first agent formulation examples B1 to B6 are used, even if the hair becomes lighter in brightness, or the dye concentration is lowered to a certain extent, or even if the time allowed for dyeing is shortened to a certain extent, the hair is dyed to a dark shade close to black hair (brightness of 3.5 or less, saturation of 3 or less in the JIS color name book).In other words, even under conditions unfavorable for dyeing due to consideration of damaged hair, it can be confirmed that the effect of dyeing lightened hair due to bleaching of melanin pigment or gray hair to a dark shade close to black hair is achieved.

[0066] [Brightness confirmation test] To more precisely evaluate the lightness of each hair strand that had undergone the above dyeing process, we measured the lightness of each strand using our tone scale. The measurement results (scale numbers or levels on our tone scale) are shown in Tables 15 to 23. While it is difficult to perfectly match the lightness of hair strands that have differences in lightness when dyeing them, if the hair is dyed to a dark tone close to black (lightness 3.5 or less, saturation 3 or less in the JIS color name book) and the lightness difference (level difference) is kept to less than 2 on our tone scale, the lightness difference becomes very inconspicuous, resulting in a finish without significant color variation due to lightness difference (color variation due to lightness difference is not noticeable).

[0067] [Table 15]

[0068] Table 16

[0069] Table 17

[0070] Table 18

[0071] Table 19

[0072] Table 20

[0073] Table 21

[0074] Table 22

[0075] Table 23

[0076] As shown in Table 15, when using Mixing Examples 2 to 8 (agents for damaged areas) of oxidative hair dyes using First Agent Formulation Example A1 to dye hair with a lightness of 15 or higher, the lightness was 6 or higher except for Mixing Example 4. When the dye lightness of Mixing Example 1, which dyed hair with a lightness of 5 (level 4), which has the lowest lightness, is used as a standard, the difference in lightness from this standard is 2 or more levels (underlined portion in the table), which means that the lightness is not uniform and an unnatural feeling can be observed. Furthermore, with the oxidative hair dyes using First Agent Formulation Examples A2 and A3, which gradually increase the amount of dye from First Agent Formulation Example A1, as shown in Tables 16 and 17, the lightness was darker overall, but under some conditions the difference in lightness was 2 or more, similar to First Agent Formulation Example A1.

[0077] In contrast, in Mixing Examples 2 to 8 (medicines for damaged areas) shown in Table 18, when the dyed hair lightness (level 4) of Mixing Example 1, which has the lowest lightness, is used as the standard, the dyed hair results in a lightness of less than level 2 in all mixing examples.As mentioned above, this, combined with the fact that the hair is dyed to a dark color tone close to black hair (lightness 3.5 or less, saturation 3 or less in the JIS color name book), makes the lightness difference very inconspicuous, resulting in a finish without large color variations due to lightness differences (color variations due to lightness differences are not noticeable).

[0078] In the case of an oxidative hair dye using Formulation Example B2, which significantly reduces the amount of dye in Formulation Example B1, as shown in Table 19, when the hair color brightness (level 4) of Blending Example 1, which produces the lowest lightness, is used as the reference, there are cases where the coloring result for yak hair (white hair) does not reach a level below 2 (underlined in the table). In the case of an oxidative hair dye using Formulation Example B3, which reduces the amount of dye in Formulation Example B1 but exceeds the amount of dye in Formulation Example B2, as shown in Table 20, when the hair color brightness (level 4) of Blending Example 1, which produces the lowest lightness, is used as the reference, the hair coloring result for all blending examples was below level 2. Therefore, it is possible to set the dye amount in Formulation Example B3 (ratio with Formulation Example B2:1:3) as the lower limit for the dye amount in the improved Formulation Example B (so that the oxidative dye contains 0.66 wt% or more of the oxidative dye relative to the total weight of the blends of Formulations 1 and 2).

[0079] Conversely, with oxidative hair dyes using formulations B4 to B6, which gradually increase the amount of dye in formulation B1, the overall lightness becomes darker, as shown in Tables 21 to 23. Using the lowest lightness level (Level 5) of blending example 1 as a reference, the dyeing results in a lightness of less than Level 2 in all blending examples. This, combined with the dark color tone (lightness 3.5 or less, saturation 3 or less in the JIS color guide) that is close to black, makes the lightness difference less noticeable, resulting in a finish without significant color variation due to lightness differences. However, under some conditions of formulation B6 (underlined in Table 23), the results measured on our tone scale are below Level 3. This results in a bluish black color, which can be unnatural and does not resemble the natural black hair of Japanese people. Therefore, in order to avoid this sense of incongruity, it is considered to set the upper limit of the amount of dye in the improved first agent formulation example B to the amount of dye in first agent formulation example B5 (ratio of 1:1 with the second agent) (so that the oxidative dye is contained in an amount of 2.63% by weight or less relative to the total mixture of the first agent and the second agent).

[0080] [Confirmation test for color variation] When hair is dyed to a dark shade close to black (a brightness of 3.5 or less and a saturation of 3 or less in the JIS color catalog) and the brightness difference (level difference) is kept below 2 on our tone scale, the result is a finish without significant color variation due to brightness differences (color variation due to brightness differences is not noticeable). However, even in this case, theoretically, color differences may be noticeable. This tendency becomes stronger as brightness and saturation increase. Furthermore, when color differences are noticeable, different hues can cause a sense of incongruity, which may significantly affect the dyeing results. Therefore, for each hair strand dyed as described above, the difference in color between Blending Examples 2 to 8 compared to Blending Example 1 was visually evaluated on a four-point scale. The results are shown in Tables 24 to 32. The color difference here refers to a comprehensive evaluation of the difference in color tone (balance of brightness and saturation) and the difference in hue (sense of incongruity). ◎: No difference in color tone is observed and there is no sense of incongruity ○: The color tone is slightly different, but there is no sense of incongruity. △: The color tone is slightly different and feels a little strange. ×: The color tone is completely different or slightly different, causing a strong sense of incongruity.

[0081] [Table 24]

[0082] [Table 25]

[0083] [Table 26]

[0084] [Table 27]

[0085] [Table 28]

[0086] [Table 29]

[0087] [Table 30]

[0088] [Table 31]

[0089] From Tables 24 to 26, it can be seen that for each of the oxidative hair dyes using First Agent Formulation Examples A1 to A3, when Blending Example 1 is used as the reference, Blending Examples 2 to 8 (drugs for damaged areas) tend to show differences in the dyed hair color when the hair brightness is lighter or the dye concentration (the concentration of the oxidative dye in the total mixture of the First and Second Agents) is lower. On the other hand, from Table 27, it can be seen that for the oxidative hair dye using First Agent Formulation Example B1, when the dyed hair color of Level 5 hair in Blending Example 1 is used as the reference, the dyeing results were close to this dyed hair color under each condition, and it was confirmed from the perspective of variation in color tone (tone and hue) that it is effective in dyeing lightened hair and gray hair due to bleaching of melanin pigment to a dark tone close to black hair without significant color variation. Regarding color variation, the oxidative hair dye using First Component Formulation Example B2, which significantly reduces the amount of dye in First Component Formulation Example B1, tends to produce visible differences in dyed hair color, as shown in Table 28. However, the oxidative hair dye using First Component Formulation Example B3, which reduces the amount of dye in First Component Formulation Example B1 but exceeds the amount of dye in First Component Formulation Example B2, does not produce significant color variation, as shown in Table 29. Conversely, the oxidative hair dye using First Component Formulation Examples B4 and B5, which gradually increase the amount of dye in First Component Formulation Example B1, also did not produce significant color variation, as shown in Tables 30 and 31. It is also clear that the oxidative hair dye using First Component Formulation Example B6, which increases the amount of dye more than First Component Formulation Example B5, does not produce significant color variation.

[0090] As can be seen from Tables 6 to 14, which show the results of the test to confirm the dark color tone close to black hair, Tables 15 to 23, which show the results of the test to confirm the lightness, and Tables 24 to 31, which show the results of the test to confirm the color tone variation, when the oxidative hair dye using First Agent Formulation Examples B1, B3 to B5 is blended, even on hair with a difference in lightness, it is possible to dye hair to a dark color tone close to black hair, achieve the desired lightness while suppressing the lightness difference, and also suppress color tone variation (variation in color tone and hue), demonstrating a superior effect to the oxidative hair dye blended using First Agent Formulation Examples A1 to A3, B2.

[0091] Furthermore, from Tables 9, 11 to 13, 18, 20 to 22, 27, 29 to 31, it can be seen that when formulating oxidative hair dyes using First Agent Formulation Examples B1, B3 to B5, stable dyeing can be achieved even when treatment is performed under dyeing conditions that take damaged hair into consideration, such as reducing the amount of alkali by changing the mixing ratio of the First Agent to the Second Agent from 1:1 to 1:2-3, reducing the usual leaving time of 30 minutes to half (15 minutes), using a second agent containing an acid (phosphoric acid in the above example) and making the mixture of the First Agent and the Second Agent closer to neutral. Of course, for example, if the second agent does not contain an acid and the mixture of the First Agent and the Second Agent is not closer to neutral, conditions are more favorable for dyeing, and it is clear that more stable dyeing can be achieved if treatment is performed under conditions that do not take such damaged hair into consideration.

[0092] The formula for Mixing Example 1 of First Agent Formulation Example B1 above is designed to dye yak hair dark gray-purple (color name "5P 3.5 / 3" in the JIS color catalog), and the formula for Mixing Example 8, which is the condition most likely to cause color change among Mixing Examples 2 to 8 of First Agent Formulation Example B1, dyes yak hair dark gray-blue-purple (color name "10PB 3 / 3" in the JIS color catalog), and no significant change in the hair dyeing results (color tone, etc.) is observed between Mixing Examples 1 to 8. This lack of significant change between Mixing Examples 1 to 8 is also seen when First Agent Formulation Examples B3 to B5 are used.

[0093] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications can be mentioned.

[0094] In the above embodiment, the case where the hair treatment agent is a two-component type has been described, but the hair treatment agent is not limited to a two-component type and may be a multi-component type, for example, a three-component or more type.

[0095] It goes without saying that the modifications given in this specification may be combined as appropriate.

Claims

1. An oxidation hair dye composition comprising a first agent containing an oxidation dye and an alkaline agent and a second agent containing an oxidizing agent, The first agent and the second agent are mixed in a weight ratio of 1:1 to 1:3, The oxidation dye is contained in an amount of 0.66 to 7.0% by weight based on the total weight of the first and second agents, paramethylaminophenol and / or a salt thereof and 2,2'-[(4-aminophenyl)imino]bisethanol and / or a salt thereof are used as precursors, and resorcinol, meta-aminophenol, and 5-aminoorthocresol are used as couplers, The composition contains, by weight ratio, more resorcinol than the total of meta-aminophenol and 5-amino-orthocresol, and more resorcinol than para-methylaminophenol and / or a salt thereof, An oxidative hair dye used to dye hair that has lost its melanin pigment or gray hair to a dark tone close to black.

2. 2. The oxidation hair dye composition according to claim 1, further comprising para-aminophenol as a precursor.

3. 3. The oxidation hair dye composition according to claim 1, wherein the alkaline agent is one or more of ammonia and monoethanolamine.

4. 4. The oxidation hair dye composition according to claim 3, which does not contain paraphenylenediamine, toluene-2,5-diamine or salts thereof as precursors.

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