JP7764121B2 - Oxidative hair dye, first agent for oxidative hair dye, second agent for oxidative hair dye, and hair dyeing method - Google Patents

Description

The present invention relates to an oxidative hair dye, a first agent for an oxidative hair dye, a second agent for an oxidative hair dye, and a hair dyeing method.

Oxidative hair dyes used to color hair work by using a dyeing principle in which oxidative dyes that have been permeated into the hair are dyed through oxidative polymerization, and they achieve longer-lasting hair color compared to other hair coloring agents such as acidic hair dyes.

As an example of an oxidative hair dye, Patent Document 1 discloses a technology that allows the inclusion of specific amounts of polyacrylic acid amide, behenyl alcohol, and polyoxyethylene behenyl ether in an oxidative hair dye to provide an oxidative hair dye that has excellent shine and other properties after dyeing.

JP 2019-043873 A

In hair dyeing treatments using oxidative hair dyes, the oxidative hair dye is applied to the desired hair so that it adheres sufficiently to achieve the desired dyeing results. Furthermore, when applying the oxidative hair dye, care is taken to avoid the oxidative hair dye adhering to areas other than the hair, such as the face, to prevent skin irritation and undesired coloring in areas other than the hair. Therefore, to ensure that the oxidative hair dye adheres to the entire hair, a certain amount of treatment time is required from the start of application to the end of application. This can result in differences in the dyeing time between hair that has the oxidative hair dye applied at the start of application and hair that has the oxidative hair dye applied at the end of application. The presence of hair with such differences in dyeing time can result in uneven, non-uniform dyeing, making it impossible to achieve uniform dyeing of the entire hair, and the desired dyeing results cannot be achieved.

In addition, hair dyeing using oxidative hair dyes can cause hair damage due to the oxidation reaction of the oxidizing agent contained in the oxidative hair dye, and there has been a demand for ways to reduce hair damage.

In view of the above circumstances, the present invention aims to provide an oxidative hair dye that can achieve uniform dyeing over the entire length of desired hair and reduce hair damage, as well as the first and second agents for the oxidative hair dye, which are components of the oxidative hair dye, and a hair dyeing method using the oxidative hair dye.

In light of the above-mentioned issues, the inventors of the present invention have come to believe that if a method for slowing down the dyeing of hair after a certain dyeing time has elapsed during hair dyeing treatment using an oxidative hair dye, it would be possible to achieve uniform dyeing of the entire hair even if the dyeing time varies depending on the hair. They also investigated methods for reducing hair damage caused by the oxidation reaction of the oxidizing agent.

After extensive research, the inventors discovered that an oxidative hair dye comprising a first agent for oxidative hair dye containing a specific oxidative dye (one or more selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine, and one or more selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol) used to dye hair in colors including blue or purple, and an alkaline agent, and a second agent for oxidative hair dye containing an oxidizing agent, wherein the second agent for oxidative hair dye contains an inorganic or organic acid, can provide an oxidative hair dye that can achieve uniform dyeing of the entire hair and reduce hair damage, as well as the first agent for oxidative hair dye and second agent for oxidative hair dye that are constituents of the oxidative hair dye, and a hair dyeing method using the oxidative hair dye.

That is, the oxidative hair dye of the present invention comprises a first agent for an oxidative hair dye containing (A) one or more compounds selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine, (B) one or more compounds selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol, and (C) an alkaline agent, and a second agent for an oxidative hair dye containing (D) an oxidizing agent and (E) an inorganic or organic acid.

The oxidation hair dye of the present invention is preferably such that the blending amount of the oxidizing agent in the second agent for the oxidation hair dye is 2.5% by mass or more, as this further promotes the oxidative polymerization of the oxidation dye and dyes the hair a deeper color including blue or purple.

In order to further reduce hair damage during hair dyeing treatment, it is preferable that the pH of the second agent for the oxidative hair dye of the present invention be 2.0 or less.

In order to further reduce hair damage during hair dyeing, the oxidative hair dye of the present invention preferably contains an inorganic acid or organic acid in the second agent of the oxidative hair dye of 1.0% by mass or more.

The oxidative hair dye of the present invention is, for example, a first agent for the oxidative hair dye that is blended with at least one selected from the group consisting of toluene-2,5-diamine and 2,4-diaminophenoxyethanol, 2,2'-[(4-aminophenyl)imino]bisethanol and 2,4-diaminophenoxyethanol, paraphenylenediamine and 2,4-diaminophenoxyethanol, toluene-2,5-diamine and α-naphthol, 2,2'-[(4-aminophenyl)imino]bisethanol and α-naphthol, paraphenylenediamine and α-naphthol, and paraphenylenediamine and meta-aminophenol.

The first agent for an oxidative hair dye of the present invention is a first agent for an oxidative hair dye in an oxidative hair dye comprising a first agent for an oxidative hair dye and a second agent for an oxidative hair dye containing (D) an oxidizing agent and (E) an inorganic or organic acid, and the first agent for an oxidative hair dye contains (A) one or more selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol, and (C) an alkaline agent.

The second agent for an oxidative hair dye of the present invention is a second agent for an oxidative hair dye comprising a first agent for an oxidative hair dye containing (A) one or more selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol, and (C) an alkaline agent, and a second agent for an oxidative hair dye, wherein (D) an oxidizing agent and (E) an inorganic or organic acid are blended into the second agent for an oxidative hair dye.

The hair dyeing method of the present invention is a hair dyeing method using any of the above-mentioned oxidative hair dyes of the present invention.

The oxidation hair dye of the present invention can provide an oxidation hair dye that can achieve uniform dyeing over the entire hair to be dyed and can reduce hair damage.
According to the first agent for an oxidative hair dye or the second agent for an oxidative hair dye of the present invention, it is possible to provide a first agent for an oxidative hair dye or a second agent for an oxidative hair dye, which are constituents of the oxidative hair dye of the present invention.
According to the hair dyeing method of the present invention, a hair dyeing method using the oxidation hair dye of the present invention can be provided.

The present invention will be described below based on an embodiment of the present invention (hereinafter referred to as the "present embodiment").

(1) Oxidative Hair Dye The oxidative hair dye of this embodiment comprises at least a first agent for oxidative hair dye and a second agent for oxidative hair dye. The oxidative hair dye of this embodiment is prepared by mixing the first agent for oxidative hair dye and the second agent for oxidative hair dye in appropriate amounts, and then applying the mixture to hair to dye the hair.
The oxidative hair dye of the present embodiment may comprise a first agent for oxidative hair dyes, a second agent for oxidative hair dyes, and other agents (such as a third agent for oxidative hair dyes) containing ingredients that can be incorporated into oxidative hair dyes. When the oxidative hair dye of the present embodiment comprises other agents, the first agent for oxidative hair dyes, the second agent for oxidative hair dyes, and the other agents can be mixed in appropriate amounts, and then applied to the hair for a hair dyeing treatment to dye the hair.

[First agent for oxidation hair dye]
The first agent for the oxidative hair dye according to the present embodiment (hereinafter, may be referred to as "the first agent according to the present embodiment") contains (A) one or more selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol, and (C) an alkaline agent.

In the following description, one or more components selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine may be collectively or individually referred to as "component (A)." Furthermore, one or more components selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol may be collectively or individually referred to as "component (B)." Furthermore, the alkaline agent may be referred to as "component (C)."

<Component (A): toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine>
The first agent according to the present embodiment contains one or more components selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine as component (A). By incorporating component (A) into the first agent according to the present embodiment together with component (B), which will be described later, it becomes possible to dye hair a color including blue or purple by a hair dyeing treatment using the oxidative hair dye according to the present embodiment.

(toluene-2,5-diamine)
The toluene-2,5-diamine blended in the first agent according to this embodiment can be one or more selected from toluene-2,5-diamine salts (toluene-2,5-diamine hydrochloride, toluene-2,5-diamine sulfate, etc.) and toluene-2,5-diamine.

The amount of toluene-2,5-diamine in the first agent according to this embodiment is not particularly limited and can be set appropriately. The "amount of toluene-2,5-diamine" refers to the amount of toluene-2,5-diamine in the first agent according to this embodiment, and when a toluene-2,5-diamine salt is used, it means the amount of toluene-2,5-diamine not containing the salt (the same applies hereinafter).
The lower limit of the amount of toluene-2,5-diamine in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the amount of toluene-2,5-diamine in the first agent according to this embodiment is preferably 9.0% by mass or less, and more preferably 7.0% by mass or less, from the viewpoint of more easily dyeing hair to a desired color (a color containing blue or purple) by reducing the risk of generating unpolymerized toluene-2,5-diamine that is not oxidatively polymerized during the hair dyeing treatment.

(2,2'-[(4-aminophenyl)imino]bisethanol)
The 2,2'-[(4-aminophenyl)imino]bisethanol blended in the first agent according to this embodiment can be one or more selected from 2,2'-[(4-aminophenyl)imino]bisethanol salts (2,2'-[(4-aminophenyl)imino]bisethanol hydrochloride, 2,2'-[(4-aminophenyl)imino]bisethanol sulfate, etc.) and 2,2'-[(4-aminophenyl)imino]bisethanol.

The amount of 2,2'-[(4-aminophenyl)imino]bisethanol in the first agent according to this embodiment is not particularly limited and can be set appropriately. The "amount of 2,2'-[(4-aminophenyl)imino]bisethanol" refers to the amount of 2,2'-[(4-aminophenyl)imino]bisethanol contained in the first agent according to this embodiment, and when a 2,2'-[(4-aminophenyl)imino]bisethanol salt is used, it means the amount of 2,2'-[(4-aminophenyl)imino]bisethanol not containing the salt (the same applies hereinafter).
The lower limit of the amount of 2,2'-[(4-aminophenyl)imino]bisethanol in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the amount of 2,2'-[(4-aminophenyl)imino]bisethanol in the first agent according to this embodiment is preferably 4.0% by mass or less, and more preferably 3.0% by mass or less, from the viewpoint of more easily dyeing hair to a desired color (a color containing blue or purple) by reducing the risk of producing unpolymerized 2,2'-[(4-aminophenyl)imino]bisethanol that is not oxidatively polymerized during the hair dyeing treatment.

(paraphenylenediamine)
The paraphenylenediamine to be blended in the first agent according to this embodiment may be one or more selected from paraphenylenediamine salts (paraphenylenediamine hydrochloride, paraphenylenediamine sulfate, etc.) and paraphenylenediamine.

The amount of paraphenylenediamine blended in the first agent according to this embodiment is not particularly limited and can be set as appropriate. The "amount of paraphenylenediamine blended" refers to the amount of paraphenylenediamine blended in the first agent according to this embodiment, and when a paraphenylenediamine salt is used, it means the amount of paraphenylenediamine blended without the salt (the same applies hereinafter).
The lower limit of the amount of paraphenylenediamine in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the amount of paraphenylenediamine in the first agent according to this embodiment is preferably 6.0% by mass or less, and more preferably 5.0% by mass or less, from the viewpoint of more easily dyeing hair to a desired color (a color containing blue or purple) by reducing the risk of generating unpolymerized paraphenylenediamine that is not oxidatively polymerized during the hair dyeing treatment.

The total amount of one or more components selected from the group consisting of toluene-2,5-diamine, 2,2'-[(4-aminophenyl)imino]bisethanol, and paraphenylenediamine (hereinafter referred to as the "total amount of component (A)") blended into the first agent according to this embodiment is not particularly limited and can be set as appropriate. The lower limit of the total amount of component (A) is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the total amount of component (A) is preferably 9.0% by mass or less, and more preferably 7.0% by mass or less, from the viewpoint of more easily achieving a desired color (color containing blue or purple) by reducing the risk of generating unpolymerized component (A) that is not oxidatively polymerized during the hair dyeing treatment.

In addition, when a dye intermediate other than the component (A) described below is further blended into the first agent according to this embodiment, the proportion of the total blend amount of component (A) relative to the total blend amount of all dye intermediates (component (A) and dye intermediates other than component (A)) blended into the first agent according to this embodiment is, for example, 50% or more, assuming that this total blend amount is 100%.

<Component (B): 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol>
The first agent according to the present embodiment contains one or more compounds selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol as component (B). By incorporating component (B) into the first agent according to the present embodiment together with component (A), which will be described later, it becomes possible to dye hair in a color including blue or purple by a hair dyeing treatment using the oxidative hair dye according to the present embodiment.

(2,4-diaminophenoxyethanol)
The 2,4-diaminophenoxyethanol to be blended in the first agent according to this embodiment can be one or more selected from 2,4-diaminophenoxyethanol salts (2,4-diaminophenoxyethanol hydrochloride, 2,4-diaminophenoxyethanol sulfate, etc.) and 2,4-diaminophenoxyethanol.

The amount of 2,4-diaminophenoxyethanol in the first agent according to this embodiment is not particularly limited and can be set appropriately. The "amount of 2,4-diaminophenoxyethanol" refers to the amount of 2,4-diaminophenoxyethanol contained in the first agent according to this embodiment, and when a 2,4-diaminophenoxyethanol salt is used, it means the amount of 2,4-diaminophenoxyethanol not containing the salt (the same applies hereinafter).
The lower limit of the amount of 2,4-diaminophenoxyethanol in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the amount of 2,4-diaminophenoxyethanol in the first agent according to this embodiment is preferably 1.0% by mass or less, and more preferably 0.8% by mass or less, from the viewpoint of more effectively dyeing hair to a desired color (color containing blue or purple) by reducing the risk of generating unpolymerized 2,4-diaminophenoxyethanol that is not oxidatively polymerized with component (A) during the hair dyeing treatment.

(α-naphthol)
The α-naphthol that can be blended into the first agent according to this embodiment is α-naphthol (also known as 1-naphthol), which is a compound in which one hydrogen atom of naphthalene is substituted with a hydroxy group.

The amount of α-naphthol in the first agent according to this embodiment is not particularly limited and can be set as appropriate.
The lower limit of the amount of α-naphthol in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the amount of α-naphthol in the first agent according to this embodiment is preferably 4.0% by mass or less, and more preferably 3.0% by mass or less, from the viewpoint of making it easier to dye hair to a desired color (a color containing blue or purple) by reducing the risk of generating unpolymerized α-naphthol that is not oxidatively polymerized with component (A) during the hair dyeing treatment.

(Metaaminophenol)
The meta-aminophenol to be blended in the first agent according to this embodiment may be one or more selected from meta-aminophenol salts (meta-aminophenol hydrochloride, meta-aminophenol sulfate, etc.) and meta-aminophenol.

The amount of meta-aminophenol in the first agent according to this embodiment is not particularly limited and can be set appropriately. The "amount of meta-aminophenol" refers to the amount of meta-aminophenol contained in the first agent according to this embodiment, and when a meta-aminophenol salt is used, it means the amount of meta-aminophenol not containing the salt (the same applies hereinafter).
The lower limit of the amount of meta-aminophenol in the first agent according to this embodiment is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more, as meta-aminophenol (when a meta-aminophenol salt is used, the amount of meta-aminophenol not including the salt) from the viewpoint of dyeing hair a deeper color including blue or purple. The upper limit of the amount of meta-aminophenol in the first agent according to this embodiment is preferably 4.0% by mass or less, and more preferably 3.0% by mass or less, as meta-aminophenol (when a meta-aminophenol salt is used, the amount of meta-aminophenol not including the salt) from the viewpoint of dyeing hair to a desired color (color including blue or purple) by reducing the risk of generating unpolymerized meta-aminophenol that is not oxidatively polymerized with component (A) during the hair dyeing treatment.

The total amount of one or more components selected from the group consisting of 2,4-diaminophenoxyethanol, α-naphthol, and meta-aminophenol (hereinafter referred to as the "total amount of component (B)") blended into the first agent according to this embodiment is not particularly limited and can be set as appropriate. The lower limit of the total amount of component (B) is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more, from the viewpoint of dyeing hair a deeper color containing blue or purple. The upper limit of the total amount of component (B) is preferably 4.0% by mass or less, and more preferably 3.0% by mass or less, from the viewpoint of more easily achieving a desired color (color containing blue or purple) by reducing the risk of generating unpolymerized component (B) that is not oxidatively polymerized with component (A) during the hair dyeing process.

In addition, when a coupler other than the component (B) described below is blended into the first agent according to this embodiment, the proportion of the total amount of component (B) blended relative to the total amount of all couplers (component (B) and couplers other than component (B)) blended into the first agent according to this embodiment is, for example, 50% or more.

Examples of combinations of components (A) and (B) blended into the first agent according to this embodiment include toluene-2,5-diamine and 2,4-diaminophenoxyethanol, 2,2'-[(4-aminophenyl)imino]bisethanol and 2,4-diaminophenoxyethanol, paraphenylenediamine and 2,4-diaminophenoxyethanol, toluene-2,5-diamine and α-naphthol, 2,2'-[(4-aminophenyl)imino]bisethanol and α-naphthol, paraphenylenediamine and α-naphthol, and paraphenylenediamine and meta-aminophenol. The first agent according to this embodiment may contain at least one of the above combinations.

The molar ratio of the molar concentration of component (A) in the first agent according to this embodiment to the molar concentration of component (B) in the first agent according to this embodiment (hereinafter sometimes referred to as "component (A) : component (B) (molar ratio)") is preferably 2:1 to 1:2, from the viewpoint of more sufficiently securing the polymer obtained by oxidative polymerization of component (A) and component (B) during the hair dyeing treatment and dyeing the hair a deeper color including blue or purple.

<Component (C): Alkaline Agent>
The first agent according to this embodiment contains one or more alkaline agents (component C). The alkaline agents promote the action of the oxidizing agent contained in the oxidation hair dye and swell the hair to improve the penetration of the dye into the hair, thereby promoting oxidative polymerization of the oxidation dye that has penetrated into the hair and improving the dyeability of the oxidation dye to the hair.

Examples of the alkaline agent include metal hydroxides such as sodium hydroxide and potassium hydroxide; metal carbonates such as sodium carbonate and potassium carbonate; metal phosphates such as sodium phosphate; ammonia; ammonium salts such as ammonium carbonate and ammonium sulfate; and alkanolamines such as monoethanolamine, triethanolamine, isopropanolamine, and 2-amino-2-methyl-1-propanol.
As the alkaline agent to be blended in the first agent according to this embodiment, it is preferable to use ammonia or an ammonium salt, or both, from the viewpoint of dyeing the hair deeply in a color including blue or purple and further improving the reduction of hair damage during the hair dyeing process.

The amount of the alkaline agent in the first agent according to this embodiment is not particularly limited and can be set as appropriate.
The lower limit of the amount of the alkaline agent is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, from the viewpoint of dyeing hair deeper in a color including blue or purple, and the upper limit of the amount of the alkaline agent is preferably 20% by mass or less, more preferably 15% by mass or less, from the viewpoint of further reducing hair damage during hair dyeing.

When ammonia is used as the alkaline agent, the blending amount is preferably 0.1% by mass or more and 20% by mass or less, from the viewpoint of dyeing the hair deeply with a blue or purple color and further reducing hair damage during the hair dyeing process. When an ammonium salt is used as the alkaline agent, the blending amount is preferably 0.1% by mass or more and 10% by mass or less, from the same viewpoint as when ammonia is used. When ammonia and an ammonium salt are used as the alkaline agent, the combined blending amount of ammonia and ammonium salt is preferably 0.1% by mass or more and 20% by mass or less, from the same viewpoint as when ammonia or an ammonium salt is used.

<Optional ingredients>
The first agent according to this embodiment may contain optional components other than components (A), (B), and (C) as appropriate. These optional components may be any known components that can be incorporated into first agents for oxidation hair dyes, and examples of such optional components include cationic surfactants, nonionic surfactants, higher alcohols, hydrocarbons, fats and oils, polyhydric alcohols, antioxidants, chelating agents, other oxidation dyes than components (A) and (B), direct dyes, and water.
Among the optional components, it is preferable that the first agent of this embodiment contains a cationic surfactant, a higher alcohol, and water, from the viewpoint of improving the viscosity of the first agent of this embodiment and imparting a soft feel to the hair after dyeing.

The cationic surfactant that can be optionally blended into the first agent according to this embodiment is a cationic surfactant that can be blended into cosmetics or quasi-drugs. The first agent according to this embodiment may contain one or more types of cationic surfactants. Examples of cationic surfactants include long-chain alkyltrimethylammonium salts, di-long-chain alkyldimethylammonium salts, tri-long-chain alkylmonomethylammonium salts, benzalkonium-type quaternary ammonium salts, and monoalkyl ether-type quaternary ammonium salts. The amount of cationic surfactant blended into the first agent according to this embodiment can be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The nonionic surfactant that can be optionally blended into the first agent according to this embodiment is a nonionic surfactant that can be blended into cosmetics or quasi-drugs. The first agent according to this embodiment may contain one or more nonionic surfactants. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol tetra fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, polyglycerin fatty acid esters, and sucrose fatty acid esters. The amount of nonionic surfactant blended into the first agent according to this embodiment can be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The first agent according to this embodiment may contain one or more types of higher alcohols that can be incorporated into cosmetics or quasi-drugs. Examples of higher alcohols that can be used include monohydric alcohols having 12 to 24 carbon atoms. Specific examples of higher alcohols include linear higher alcohols such as myristyl alcohol, cetanol, oleyl alcohol, stearyl alcohol, and behenyl alcohol, and branched higher alcohols such as isocetyl alcohol, octyldodecanol, and isostearyl alcohol. The amount of higher alcohol incorporated into the first agent according to this embodiment may be set as appropriate, but is, for example, 1% by mass or more and 20% by mass or less.

The first agent according to this embodiment may contain one or more polyhydric alcohols that can be incorporated into cosmetics or quasi-drugs. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, glycerin, diglycerin, and butylene glycol. The amount of polyhydric alcohol incorporated into the first agent according to this embodiment may be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The first agent according to this embodiment may optionally contain one or more hydrocarbons that can be incorporated into cosmetics or quasi-drugs. Examples of hydrocarbons include liquid paraffin, squalane, pristane, ozokerite, paraffin, ceresin, petrolatum, and microcrystalline wax. The amount of hydrocarbon incorporated into the first agent according to this embodiment may be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The first agent according to this embodiment may contain one or more types of oils and fats that can be incorporated into cosmetics or quasi-drugs. Examples of oils and fats include hydrogenated oil, almond oil, avocado oil, olive oil, shea butter oil, evening primrose oil, camellia oil, peanut oil, and rosehip oil. The amount of oil and fat incorporated into the first agent according to this embodiment may be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The first agent according to this embodiment may optionally contain one or more antioxidants that can be incorporated into cosmetics or quasi-drugs. Examples of antioxidants include ascorbic acid, sulfurous acid, and salts thereof. The amount of antioxidant incorporated into the first agent according to this embodiment may be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

Water may be optionally blended into the first agent according to this embodiment. The amount of water blended into the first agent according to this embodiment may be set as appropriate, but may be, for example, 40% by mass or more and 90% by mass or less.

(Other oxidation dyes)
The first agent according to this embodiment may optionally contain one or more oxidative dyes other than the components (A) and (B). By incorporating other oxidative dyes, it becomes possible to dye hair in various shades, including blue or purple.

When a dye intermediate other than component (A) is further blended as another oxidation dye in the first agent according to this embodiment, dye intermediates such as phenylenediamine derivatives such as toluene-3,4-diamine; and phenol derivatives such as paramethylaminophenol, orthoaminophenol, and paraaminophenol can be used.
Furthermore, when a coupler other than component (B) is further blended as another oxidative dye in the first agent according to this embodiment, couplers such as phenylenediamine derivatives such as metaphenylenediamine; aminophenol derivatives such as 5-aminoorthocresol and 5-(2-hydroxyethylamino)-2-methylphenol; and resorcinol can be used.

The amount of other oxidative dyes in the first agent according to this embodiment may be set as appropriate, but is, for example, 0.01% by mass or more and 5.0% by mass or less.

The first agent according to this embodiment may contain no other oxidative dyes, or the amount of other oxidative dyes may be 50% or less, assuming that the total amount of all oxidative dyes contained in the first agent (the sum of the amounts of component (A), component (B), and other oxidative dyes) is 100%.

In order to prevent temperature changes in the first agent according to this embodiment due to heat generation or heat absorption during production caused by the neutralization reaction with the alkaline agent, it is preferable that the first agent according to this embodiment does not contain an inorganic acid or an organic acid, or that the amount of inorganic acid or organic acid contained is 1.0 mass% or less.

<Viscosity>
The viscosity of the first agent according to this embodiment is set as appropriate, but is, for example, 5,000 mPa·s or more and 50,000 mPa·s or less. Here, the viscosity of the first agent according to this embodiment is the value measured after 60 seconds at 25°C using a Brookfield viscometer with a rotor selected according to the viscosity. The rotor rotation speed during measurement is preferably, for example, 12 rpm.

<pH>
The pH of the first agent according to this embodiment is preferably 8.0 or more and 12.0 or less, and more preferably 8.5 or more and 11.5 or less. The pH is measured at 25°C.

<Alkalinity>
The alkalinity of the first agent according to this embodiment is, for example, 1.0 or more and 25.0 or less. Here, "alkalinity" refers to the volume of 0.1 mol/L hydrochloric acid required to neutralize 1 g of the first agent for the oxidation hair dye (unit of alkalinity: ml). The alkalinity can be adjusted using the alkaline agent.

<Dosage form>
The dosage form of the first agent according to this embodiment may be appropriately determined, and examples of the dosage form include liquid, cream, gel, and powder.

[Second agent for oxidation hair dye]
The second agent for the oxidative hair dye according to the present embodiment (hereinafter, sometimes referred to as the "second agent according to the present embodiment") contains (D) an oxidizing agent and (E) an inorganic acid or an organic acid.

In the following description, the oxidizing agent may be referred to as "component (D)," and inorganic or organic acids may be referred to collectively or individually as "component (E)."

<Component (D): Oxidizing Agent>
The second agent according to this embodiment contains one or more oxidizing agents (component (D)). The oxidizing agent functions to promote oxidative polymerization of the oxidative dye contained in the oxidative hair dye through an oxidation reaction.
Examples of the oxidizing agent include hydrogen peroxide, bromate, percarbonate, perborate, etc. As the oxidizing agent, hydrogen peroxide is preferred from the viewpoints of dyeing hair deeply in a color including blue or purple and having an excellent bleaching effect on hair (an effect of bleaching melanin pigment in hair).

The amount of oxidizing agent contained in the second agent according to this embodiment is not particularly limited and can be set as appropriate.
The lower limit of the amount of the oxidizing agent to be blended is preferably 2.5% by mass or more, more preferably 3.0% by mass or more, more preferably 3.5% by mass or more, and even more preferably 4.0% by mass or more, from the viewpoint of further promoting the oxidative polymerization of the oxidation dye and dyeing the hair a deeper color including blue or purple. The upper limit of the amount of the oxidizing agent to be blended is preferably 7.0% by mass or less, more preferably 6.0% by mass or less, from the viewpoint of further improving the reduction of hair damage during hair dyeing treatment.

The mass ratio of the amount of component (C) in the first agent according to this embodiment to the amount of component (D) in the second agent according to this embodiment (hereinafter sometimes referred to as the "mass ratio (C)/(D)") is not particularly limited, but for example, the mass ratio (C)/(D) is 0.1 or more and 10 or less.

<Component (E): Inorganic or Organic Acid>
The second agent for the oxidative hair dye according to this embodiment contains one or more inorganic or organic acids as component (E). Therefore, the hair styling composition according to this embodiment may contain either an inorganic acid or an organic acid, or may contain both an inorganic acid and an organic acid. The inclusion of an inorganic acid or an organic acid makes it possible to reduce hair damage during hair dyeing using an oxidative hair dye.

Examples of the inorganic acid include phosphoric acid, sulfuric acid, hydrochloric acid, boric acid, etc. Among the inorganic acids, phosphoric acid is preferred from the viewpoints of achieving uniform dyeing of the entire hair to be dyed and further reducing hair damage.
Examples of the organic acid include citric acid, levulinic acid, glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, succinic acid, maleic acid, etc. Among the organic acids, citric acid is preferred from the viewpoints of achieving excellent uniform dyeing of the entire hair to be dyed and further reducing hair damage.

The second agent for the oxidative hair dye according to this embodiment preferably contains an inorganic acid, from the viewpoint that dyeing hair to the desired color (colors including blue or purple) can be more easily achieved by more sufficiently securing the polymer obtained by oxidative polymerization of component (A) and component (B) during the hair dyeing process.
In addition to the above viewpoints, when the second agent for the oxidative hair dye according to this embodiment contains hydrogen peroxide as an oxidizing agent, it is preferable that the second agent for the oxidative hair dye according to this embodiment contains an inorganic acid, in order to further improve the storage stability of the hydrogen peroxide contained in the second agent.

The amount of inorganic acid or organic acid blended in the second agent for the oxidative hair dye according to this embodiment is not particularly limited and can be set appropriately.
The lower limit of the amount of inorganic acid or organic acid in the second agent for the oxidative hair dye according to this embodiment is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more, from the viewpoint of further reducing hair damage during hair dyeing treatment. The upper limit of the amount of inorganic acid or organic acid in the second agent for the oxidative hair dye according to this embodiment is preferably 10.0% by mass or less, and more preferably 5.0% by mass or less, from the viewpoint of dyeing hair darker in a color including blue or purple.

The mass ratio of the amount of component (E) to the amount of component (D) blended in the second agent according to this embodiment (hereinafter sometimes referred to as the "mass ratio (E)/(D)") is not particularly limited, but for example, the mass ratio (E)/(D) is 0.1 or more and 5.0 or less.

<Optional ingredients>
The second agent according to this embodiment may contain optional components other than the components (D) and (E) as appropriate. The optional components may be any known components that can be incorporated into second agents for oxidation hair dyes, such as nonionic surfactants, higher alcohols, hydrocarbons, fats and oils, polyhydric alcohols, antioxidants, chelating agents, and water.
Among the optional components, it is preferable that a nonionic surfactant, a higher alcohol, and water be blended into the second agent of this embodiment, from the viewpoint of improving the viscosity of the second agent of this embodiment.

The nonionic surfactant that can be optionally blended into the second agent according to this embodiment is a nonionic surfactant that can be blended into cosmetics or quasi-drugs. The second agent according to this embodiment may contain one or more nonionic surfactants. Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol tetra fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, polyglycerin fatty acid esters, and sucrose fatty acid esters. The amount of nonionic surfactant blended into the second agent according to this embodiment can be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

The second agent according to this embodiment may contain one or more higher alcohols that can be incorporated into cosmetics or quasi-drugs. Monohydric alcohols having 12 to 24 carbon atoms can be used as the higher alcohol. Examples of higher alcohols include linear higher alcohols such as myristyl alcohol, cetanol, oleyl alcohol, stearyl alcohol, and behenyl alcohol, and branched higher alcohols such as isocetyl alcohol, octyldodecanol, and isostearyl alcohol. The amount of higher alcohol incorporated into the second agent according to this embodiment can be set as appropriate, but is, for example, 0.1% by mass or more and 10% by mass or less.

Water may be optionally blended into the second agent according to this embodiment. The amount of water blended into the second agent according to this embodiment may be set as appropriate, but may be, for example, 50% by mass or more and 90% by mass or less.

<Viscosity>
The viscosity of the second agent according to this embodiment is set as appropriate, but is, for example, 100 mPa·s or more and 30,000 mPa·s or less. Here, the viscosity of the first agent according to this embodiment is the value measured after 60 seconds at 25°C using a Brookfield viscometer with a rotor selected according to the viscosity. The rotor rotation speed during measurement is preferably, for example, 12 rpm.

<pH>
The pH of the second agent according to this embodiment is not particularly limited and can be set appropriately.
The lower limit of the pH of the second agent for the oxidative hair dye according to this embodiment is, for example, 0.5 or more. When hydrogen peroxide is blended into the second agent, the lower limit of the pH is preferably 0.5 or more, and more preferably 1.0 or more, from the viewpoint of further improving the storage stability of the hydrogen peroxide blended in the second agent.
The upper limit of the pH of the second agent for the oxidative hair dye according to this embodiment is preferably 2.0 or less, and more preferably 1.5 or less, from the viewpoint of further reducing hair damage during hair dye treatment. The pH is measured at 25°C.

<Dosage form>
The dosage form of the second agent according to this embodiment may be appropriately determined, and examples of the dosage form include liquid, cream, gel, and powder.

[Method of manufacturing an oxidation hair dye]
The oxidative hair dye of this embodiment can be produced by any known method for producing cosmetics. Similarly, the first agent of this embodiment and the second agent of this embodiment can be produced by any known method for producing cosmetics.

[How to use oxidation hair dye]
The oxidative hair dye of this embodiment can be used in a known manner for oxidative hair dyes. For example, the oxidative hair dye of this embodiment can be used by mixing appropriate amounts of a first agent for an oxidative hair dye and a second agent for an oxidative hair dye to obtain an oxidative hair dye (the mixing ratio of the first agent to the second agent is, for example, First Agent:Second Agent = 1 part by mass:0.3 to 3 parts by mass), applying the oxidative hair dye to wet or dry hair, leaving it for a predetermined time (for example, 5 minutes to 30 minutes; from the viewpoint of sufficient hair dyeing, a leaving time of 15 minutes to 30 minutes is preferable), rinsing, drying the hair, and then dyeing the hair.

<Hair types for which oxidative hair dyes are used>
The target hair to be treated with the oxidative hair dye of this embodiment is not particularly limited, and can include hair that has a history of being dyed with an oxidative hair dye, hair that has not a history of being dyed with an oxidative hair dye, etc.

(2) Hair dyeing method using an oxidative hair dye The hair dyeing method of the present embodiment is a hair dyeing method using the oxidative hair dye of the present embodiment.
The hair dyeing method of this embodiment may employ any known hair dyeing method using an oxidative hair dye, except for using the oxidative hair dye of this embodiment. The hair dyeing method of this embodiment is not particularly limited, but may involve, for example, mixing appropriate amounts of the first agent of this embodiment and the second agent of this embodiment to obtain the oxidative hair dye of this embodiment (the mixing ratio of the first agent to the second agent is, for example, First Agent:Second Agent = 1 part by mass:0.3 to 3 parts by mass), applying the mixture to wet or dry hair, leaving it for a predetermined time (for example, the leaving time is 5 minutes to 30 minutes; from the viewpoint of sufficient hair dyeing, a leaving time of 15 minutes to 30 minutes is preferable), rinsing, and drying the hair.

The present invention will be described in detail below based on examples, but the present invention should not be construed as being limited by the descriptions in these examples.

[1] Hair dyeing evaluation Hair dyeing evaluation was carried out as shown below.

(Preparation of First Agent and Second Agent for Oxidative Hair Dye)
Formulations 1-1 to 1-7 of the first agents for the oxidative hair dye according to this embodiment and formulations 2-1 to 2-4 of the second agents for the oxidative hair dye according to this embodiment used in the hair dyeing evaluation were prepared as follows.

(Prescription 1-1 to Prescription 1-7)
Formulations 1-1 to 1-7 of the first agent for the oxidation hair dye according to this embodiment were prepared by mixing components to obtain the compositions shown in Table 1. In the column for the components in Table 1, the numbers indicate mass % and "-" indicates that the component is not blended. In Formulations 1-1 to 1-7, the blending amounts of toluene-2,5-diamine sulfate, 2,2'-[(4-aminophenyl)imino]bisethanol sulfate, and paraphenylenediamine were each 1 mM in molar concentration, and the blending amounts of 2,4-diaminophenoxyethanol hydrochloride, α-naphthol, and meta-aminophenol were each 0.5 mM in molar concentration. The pH (25°C) of Formulations 1-1 to 1-7 was 10.0.

Formulations 2-1 to 2-4 of the second agent for the oxidation hair dye according to this embodiment were mixed to prepare the compositions shown in Table 2. In the column for blended components in Table 2, the numbers indicate mass % and "-" indicates that the component is not blended.
The pH (25°C) of formulation 2-1 was 1.1, the pH (25°C) of formulation 2-2 was 1.7, the pH (25°C) of formulation 2-3 was 4.0, and the pH (25°C) of formulation 2-4 was 4.6.

(Hair dyeing treatment 1)
The first agents for the oxidative hair dyes of Formulations 1-1 to 1-7 prepared above and the second agents for the oxidative hair dyes of Formulations 2-1 to 2-3 prepared above were mixed in a 100 mL vial in the combinations shown in Table 4, Table 6, Table 8, Table 10, Table 12, Table 14, or Table 16 below, at a mass ratio of 50 g each, to obtain the oxidative hair dyes of Examples 1a to 2g and Comparative Examples 1a to 2g, respectively. Next, a white hair bundle (yak hair bundle "BM-YK-A" manufactured by Beaulux) was placed in the 100 mL vial containing each oxidative hair dye, and the hair was dyed by shaking for 10, 20, and 30 minutes in a thermostatic bath set to 25°C. Immediately after the completion of each dyeing time, the hair bundles dyed for 10 minutes, 20 minutes, and 30 minutes were removed from the 100 mL vial and rinsed with warm water. Each hair bundle was then washed with shampoo (Deesse's Noidue Silky Luxe Shampoo manufactured by Milbon Co., Ltd.), and then dried with warm air while being combed. The hair bundles dyed for 10 minutes, 20 minutes, or 30 minutes in each example or comparative example were dyed so that N=3 for each condition.

(Evaluation of Hair Dyeing Using K/S Value)
For each hair bundle that had been dyed with the oxidative hair dye of Examples 1a to 2g or Comparative Examples 1a to 2g one day earlier, measurements were taken six times using a spectrophotometer (CM-5, manufactured by Konica Minolta) in SCE measurement mode (specular reflection excluded) at different measurement sites to measure the reflectance (Rλ) in the wavelength range of 360 nm to 740 nm. Similarly, the reflectance (Rλ) of a hair bundle that had not been dyed was also measured.

Next, using the reflectance (Rλ) values in each wavelength region, the K/S value was calculated by converting using the average value (N=3) of the measured reflectance (Rλ) values of the hair strands treated with the oxidative hair dyes of Examples 1a to 2g and Comparative Examples 1a to 2g using the KuBellka-Munk function. The formula for calculating the K/S value is as follows:
K/S value={1−(average value of reflectance (Rλ) at each absorption wavelength (nm) (N=3)/100)} ² /{2×(average value of reflectance (Rλ) at each absorption wavelength (nm) (N=3)/100)}
The K/S value is used to evaluate the surface dye concentration of the hair bundle, and a higher K/S value means a higher surface dye concentration of the hair bundle.

Next, the absorption wavelength at which the maximum K/S value was obtained for each oxidative hair dye after 10 minutes of dyeing was selected from the K/S values calculated for hair strands dyed with the oxidative hair dyes of Examples 1a to 2g or Comparative Examples 1a to 2g. The K/S values for each oxidative hair dye at that absorption wavelength after 10, 20, and 30 minutes of dyeing were then used to calculate the "change in surface dye concentration (x) after 20 minutes of dyeing" according to the following formula:
Change in surface dye concentration after 20 minutes of dyeing (x) = {(K/S value after 30 minutes of dyeing) - (K/S value after 20 minutes of dyeing)}/{(K/S value after 20 minutes of dyeing) - (K/S value after 10 minutes of dyeing)}

This change in surface dye concentration (x) after 20 minutes of dyeing is evaluated to assess the progress of dyeing on the hair after 20 minutes of dyeing, using the change in K/S value from 10 minutes to 20 minutes of dyeing and the change in K/S value from 20 minutes to 30 minutes of dyeing. Therefore, a smaller change in surface dye concentration (x) indicates a smaller difference in K/S value (surface dye concentration) from 20 minutes to 30 minutes of dyeing compared to the difference in K/S value (surface dye concentration) from 10 minutes to 20 minutes of dyeing, which can be evaluated as indicating a slower progress of dyeing on the hair after 20 minutes of dyeing. Furthermore, since it often takes about 20 minutes for an oxidative hair dye to achieve sufficient dyeing, oxidative hair dyes that are evaluated as showing a slower dyeing of the hair after 20 minutes (the value of the change in surface dye concentration (x) becomes smaller) can be said to be capable of achieving the desired uniform dyeing of the entire hair.

The absorption wavelengths showing the maximum K/S values for each of the above-mentioned oxidation hair dyes after a dyeing time of 10 minutes were as follows:
Examples 1a and 2a and Comparative Examples 1a and 2a: 620 nm
Examples 1b and 2b and Comparative Examples 1b and 2b: 640 nm
Examples 1c and 2c and Comparative Examples 1c and 2c: 600 nm
Examples 1d and 2d and Comparative Examples 1d and 2d: 570 nm
Examples 1e and 2e and Comparative Examples 1e and 2e: 620 nm
Examples 1f and 2f and Comparative Examples 1f and 2f: 560 nm
Examples 1g and 2g and Comparative Examples 1g and 2g: 540 nm

[2] Evaluation of Hair Damage Hair damage was evaluated as follows.

(Preparation of First Agent and Second Agent for Oxidative Hair Dye)
Formulations 1-8 to 1-14 of the first agents for the oxidative hair dye used in the evaluation of hair damage were prepared as follows: Formulations 2-1 to 2-4 in Table 2 prepared in the above hair dye evaluation were used as the second agents for the oxidative hair dye.

(Prescription 1-8 to Prescription 1-14)
Formulations 1-8 to 1-14 of the first agent for an oxidative hair dye according to this embodiment were prepared by mixing the ingredients other than component (A), component (B), and purified water, and their amounts, from the formulation shown in Table 1, in the same manner as in Formulation 1-1 in Table 1, with the types and amounts of component (A) and component (B) shown in Table 3 (the numbers in Table 3 indicate mass %), and adding purified water to make a total of 100 mass %. In Formulations 1-8 to 1-14, the molar concentrations of toluene-2,5-diamine sulfate, 2,2'-[(4-aminophenyl)imino]bisethanol sulfate, and paraphenylenediamine were each 1 μM, and the molar concentrations of 2,4-diaminophenoxyethanol hydrochloride, α-naphthol, and meta-aminophenol were each 0.5 μM. The pH (25°C) of Formulations 1-8 to 1-14 was 10.0.

(Hair dyeing treatment 2)
The first agents for the oxidative hair dyes of Formulations 1-8 to 1-14 prepared above and the second agents for the oxidative hair dyes of Formulations 2-1 to 2-4 prepared above were mixed in a 100 mL vial in the combinations shown in Table 5, Table 7, Table 9, Table 11, Table 13, Table 15, or Table 17 below, at a mass ratio of 50 g each of the first agent for the oxidative hair dyes and the second agent for the oxidative hair dyes, so as to give a mass ratio of 1:1, thereby obtaining the oxidative hair dyes of Examples 3a to 4g and Comparative Examples 3a to 4g, respectively. Subsequently, a black hair tress (Beaulux black human hair tress "BS-B-A") was placed in the 100 mL vial containing each oxidative hair dye, and the hair was dyed by shaking for 30 minutes in a thermostatic bath set at 25°C. Immediately after the dyeing time was over, each hair bundle was removed from the 100 mL vial and rinsed with warm water, and then each hair bundle was washed with shampoo (Deesse Noidue Silky Luxe Shampoo, manufactured by Milbon Co., Ltd.), and then dried with warm air while combing. The dyeing process was performed so that N = 3 under each condition.

(Evaluation of hair damage)
For each hair bundle that had been dyed with the oxidative hair dye of Examples 3a to 4g or Comparative Examples 3a to 4g one day earlier, and for a black hair bundle that had not been dyed (untreated hair bundle), measurements were taken six times using a spectrophotometer (CM-5, manufactured by Konica Minolta) in the SCE measurement mode (specular reflection removed) while changing the measurement site. ΔL* was calculated as the difference between the average L* value (N=3) of each dyed hair bundle and the average L* value (N=3) of untreated hair bundles.
The smaller the ΔL* value, the closer it is to the lightness value of untreated hair, which indicates that the bleaching action (bleaching of melanin pigment in hair) that accompanies an oxidation reaction on hair is weaker, and therefore indicates that hair damage caused by the oxidation reaction during hair dyeing is reduced.

[Evaluation results]
The results of the hair dye evaluation and hair damage evaluation using each Example or Comparative Example are shown in Tables 4 to 17.

(Evaluation result 1)
Tables 4 and 5 below show the evaluation results of the oxidative hair dyes of Examples 1a to 4a and Comparative Examples 1a to 4a, which used either the first agent for the oxidative hair dye of Formulation 1-1 or Formulation 1-8 (both containing a combination of toluene-2,5-diamine sulfate and 2,4-diaminophenoxyethanol hydrochloride) or the second agent for the oxidative hair dye of Formulations 2-1 to 2-4.

The evaluation results shown in Table 4 above show that Example 1a (Formula 2-1, in which phosphoric acid is added to the second agent for the oxidative hair dye) and Example 2a (Formula 2-2, in which citric acid is added to the second agent for the oxidative hair dye) had smaller values for the change in surface dye concentration (x) after 20 minutes of dyeing compared to Comparative Example 2a (Formula 2-4, in which no inorganic or organic acid is added to the second agent for the oxidative hair dye), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing.

The evaluation results shown in Table 5 above show that Example 3a (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4a (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3a (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 4 and 5 together, it can be seen that oxidative hair dyes containing toluene-2,5-diamine sulfate and 2,4-diaminophenoxyethanol hydrochloride, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing compared to those without phosphoric acid or citric acid. This shows that this product can achieve the desired uniform dyeing of the entire hair and is excellent at reducing hair damage.

(Evaluation result 2)
Tables 6 and 7 below show the evaluation results of the oxidative hair dyes of Examples 1b to 4b and Comparative Examples 1b to 4b, which use either the first agent for the oxidative hair dye of Formulation 1-2 or Formulation 1-9 (both of which contain a combination of 2,2'-[(4-aminophenyl)imino]bisethanol sulfate and 2,4-diaminophenoxyethanol hydrochloride) or the second agent for the oxidative hair dye of Formulations 2-1 to 2-4.

The evaluation results shown in Table 6 above show that Example 1b (containing phosphoric acid in the second agent for oxidative hair dye (Formulation 2-1)) and Example 2b (containing citric acid in the second agent for oxidative hair dye (Formulation 2-2)) had smaller changes in surface dye concentration (x) after 20 minutes of dyeing compared to Comparative Example 2b (containing no inorganic or organic acid in the second agent for oxidative hair dye (Formulation 2-4)), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing.

The evaluation results shown in Table 7 above show that Example 3b (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4b (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3b (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 6 and 7 together, it can be seen that oxidative hair dyes containing 2,2'-[(4-aminophenyl)imino]bisethanol sulfate and 2,4-diaminophenoxyethanol hydrochloride, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing compared to those without phosphoric acid or citric acid, demonstrating that this product can achieve the desired uniform dyeing of the entire hair and is excellent at reducing hair damage.

(Evaluation result 3)
Tables 8 and 9 below show the evaluation results of the oxidative hair dyes of Examples 1c to 4c and Comparative Examples 1c to 4c, which used either the first agent for the oxidative hair dye of Formulation 1-3 or Formulation 1-10 (both of which contain a combination of paraphenylenediamine and 2,4-diaminophenoxyethanol hydrochloride) or the second agent for the oxidative hair dye of Formulations 2-1 to 2-4.

The evaluation results shown in Table 8 above show that Example 1c (containing phosphoric acid in the second agent for the oxidative hair dye (Formulation 2-1)) and Example 2c (containing citric acid in the second agent for the oxidative hair dye (Formulation 2-2)) had smaller changes in surface dye concentration (x) after 20 minutes of dyeing compared to Comparative Example 1c and Comparative Example 2c (containing no inorganic or organic acid in the second agent for the oxidative hair dye (Formulation 2-3, Formulation 2-4)), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing.

The evaluation results shown in Table 9 above show that Example 3c (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4c (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3c (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 8 and 9 together, it can be seen that oxidative hair dyes containing paraphenylenediamine and 2,4-diaminophenoxyethanol hydrochloride that also contain phosphoric acid or citric acid showed slower dyeing of the hair after 20 minutes of dyeing time compared to those without phosphoric acid or citric acid, demonstrating that they are capable of achieving the desired uniform dyeing of the entire hair and are excellent at reducing hair damage.

(Evaluation result 4)
Tables 10 and 11 below show the evaluation results of the oxidative hair dyes of Examples 1d to 4d and Comparative Examples 1d to 4d, which used either the first agent for the oxidative hair dye of Formulation 1-4 or Formulation 1-11 (both of which contain a combination of toluene-2,5-diamine sulfate and α-naphthol) or the second agent for the oxidative hair dye of Formulations 2-1 to 2-4.

The evaluation results shown in Table 10 above show that Example 1d (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 2d (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) had smaller values for the change in surface dye concentration (x) after 20 minutes of dyeing time compared to Comparative Example 1d and Comparative Example 2d (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3, Formulation 2-4)), indicating that the progress of hair dyeing after 20 minutes of dyeing time was slower.

The evaluation results shown in Table 11 above show that Example 3d (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4d (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3d (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 10 and 11 together, it can be seen that oxidative hair dyes containing toluene-2,5-diamine sulfate and α-naphthol, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing time compared to those without phosphoric acid or citric acid. This shows that the desired uniform dyeing of the entire hair can be achieved and that these products are excellent at reducing hair damage.

(Evaluation result 5)
Tables 12 and 13 below show the evaluation results of the oxidative hair dyes of Examples 1e to 4e and Comparative Examples 1e to 4e, which used either the first agent for the oxidative hair dye of Formulation 1-5 or Formulation 1-12 (both of which contain a combination of 2,2'-[(4-aminophenyl)imino]bisethanol sulfate and α-naphthol) or the second agent for the oxidative hair dye of Formulations 2-1 to 2-4.

The evaluation results shown in Table 12 above show that Example 1e (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 2e (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) had smaller changes in surface dye concentration (x) after 20 minutes of dyeing time compared to Comparative Example 1e and Comparative Example 2e (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3, Formulation 2-4)), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing time.

The evaluation results shown in Table 13 above show that Example 3e (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4e (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3e (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 12 and 13 together, it can be seen that oxidative hair dyes containing 2,2'-[(4-aminophenyl)imino]bisethanol sulfate and α-naphthol, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing compared to those without phosphoric acid or citric acid. This indicates that the desired uniform dyeing of the entire hair can be achieved and that these products are excellent at reducing hair damage.

(Evaluation result 6)
Tables 14 and 15 below show the evaluation results of the oxidative hair dyes of Examples 1f to 4f and Comparative Examples 1f to 4f, which used either the first agent for the oxidative hair dye of Formulation 1-6 or Formulation 1-13 (both of which contain a combination of paraphenylenediamine and α-naphthol) or the second agent for the oxidative hair dye of Formulation 2-1 to 2-4.

From the evaluation results shown in Table 14 above, Example 1f (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 2f (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) had smaller values for the change in surface dye concentration (x) after 20 minutes of dyeing time compared to Comparative Example 1f and Comparative Example 2f (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3, Formulation 2-4)), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing time.

The evaluation results shown in Table 15 above show that Example 3f (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4f (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3f (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 14 and 15 together, it can be seen that oxidative hair dyes containing paraphenylenediamine and α-naphthol, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing compared to those without phosphoric acid or citric acid, making it possible to achieve the desired uniform dyeing of the entire hair and also being excellent at reducing hair damage.

(Evaluation result 7)
Tables 16 and 17 below show the evaluation results of the oxidative hair dyes of Examples 1g to 4g and Comparative Examples 1g to 4g, which used either the first agent for the oxidative hair dye of Formulation 1-7 or Formulation 1-14 (both containing a combination of paraphenylenediamine and meta-aminophenol) or the second agent for the oxidative hair dye of Formulation 2-1 to 2-4.

The evaluation results shown in Table 16 above show that Example 1g (containing phosphoric acid in the second agent for oxidative hair dye (Formulation 2-1)) and Example 2g (containing citric acid in the second agent for oxidative hair dye (Formulation 2-2)) had smaller changes in surface dye concentration (x) after 20 minutes of dyeing compared to Comparative Example 2g (containing no inorganic or organic acid in the second agent for oxidative hair dye (Formulation 2-4)), indicating that the dyeing of the hair progressed more slowly after 20 minutes of dyeing.

The evaluation results shown in Table 17 above show that Example 3g (phosphoric acid added to the second agent for oxidative hair dye (Formulation 2-1)) and Example 4g (citric acid added to the second agent for oxidative hair dye (Formulation 2-2)) have lower ΔL* values than Comparative Example 3g (no inorganic or organic acid added to the second agent for oxidative hair dye (Formulation 2-3)), demonstrating their superior ability to reduce hair damage.

Considering the results shown in Tables 16 and 17 together, it can be seen that oxidative hair dyes containing paraphenylenediamine and meta-aminophenol, which also contain phosphoric acid or citric acid, showed slower dyeing of the hair after 20 minutes of dyeing time compared to those without phosphoric acid or citric acid, making it possible to achieve the desired uniform dyeing of the entire hair and also being excellent at reducing hair damage.

[3] Preparation of Second Agent for Oxidative Hair Dye The second agent for oxidative hair dye (Formulation Example 2-5) was mixed to prepare the following composition.
The pH (25° C.) of Formulation Example 2-5 was 1.3.

(Prescription Example 2-5)
Hydrogen peroxide solution 6% by mass
Phosphoric acid 1.0% by mass
Chelating agent 0.2% by mass
Purified water 92.8% by mass

Claims (8)

(A) one or more selected from the group consisting of toluene-2,5-diamine and 2,2'-[(4-aminophenyl)imino]bisethanol;
(B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and
(C) An alkaline agent is blended,
the molar ratio of (A) the molar concentration of one or more selected from the group consisting of toluene-2,5-diamine and 2,2'-[(4-aminophenyl)imino]bisethanol to (B) the molar concentration of one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol is (A):(B) 2:1 to 1:2;
A first agent for an oxidation hair dye;
(D) an oxidizing agent, and
(E) phosphoric acid or an organic acid is blended,
the organic acid is one or more selected from citric acid, levulinic acid, glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, succinic acid, and maleic acid;
The blending amount of the (E) phosphoric acid or organic acid is 1.0 mass% or more,
A second agent for an oxidation hair dye;
Oxidative hair dye with (A) 2,2'-[(4-aminophenyl)imino]bisethanol,
(B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and
(C) a first agent for an oxidation hair dye containing an alkaline agent;
(D) an oxidizing agent, and
(E) phosphoric acid or an organic acid is blended,
the organic acid is one or more selected from citric acid, levulinic acid, glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, succinic acid, and maleic acid;
The blending amount of the (E) phosphoric acid or organic acid is 1.0 mass% or more,
A second agent for an oxidation hair dye;
Oxidative hair dye with The oxidative hair dye according to claim 2, wherein the molar ratio of (A) 2,2'-[(4-aminophenyl)imino]bisethanol to (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol blended in the first agent for the oxidative hair dye is (A):(B) 2:1 to 1:2. The oxidative hair dye according to any one of claims 1 to 3, wherein the amount of oxidizing agent in the second agent for the oxidative hair dye is 2.5% by mass or more. The oxidative hair dye according to any one of claims 1 to 4, wherein the pH of the second agent for the oxidative hair dye is 2.0 or less. A first agent for an oxidative hair dye comprising: a first agent for an oxidative hair dye; and a second agent for an oxidative hair dye, which contains (D) an oxidizing agent and (E) phosphoric acid or an organic acid, the organic acid being one or more selected from citric acid, levulinic acid, glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, succinic acid, and maleic acid, and the amount of (E) phosphoric acid or organic acid is 1.0 mass% or more,
(A) one or more selected from the group consisting of toluene-2,5-diamine and 2,2'-[(4-aminophenyl)imino]bisethanol, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and (C) an alkaline agent, or
A first agent for an oxidation hair dye, which contains (A) 2,2'-[(4-aminophenyl)imino]bisethanol, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and (C) an alkaline agent. (A) one or more selected from the group consisting of toluene-2,5-diamine and 2,2'-[(4-aminophenyl)imino]bisethanol, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and (C) an alkaline agent, or
a first agent for an oxidation hair dye, which contains (A) 2,2'-[(4-aminophenyl)imino]bisethanol, (B) one or more selected from the group consisting of 2,4-diaminophenoxyethanol and α-naphthol, and (C) an alkaline agent;
A second agent for an oxidation hair dye in an oxidation hair dye comprising:
A second agent for an oxidation hair dye, comprising (D) an oxidizing agent and (E) phosphoric acid or an organic acid, wherein the organic acid is one or more selected from citric acid, levulinic acid, glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, succinic acid, and maleic acid, and the blending amount of the (E) phosphoric acid or organic acid is 1.0 mass% or more. A hair dyeing method using the oxidative hair dye according to any one of claims 1 to 5.