The hair dye of the present invention comprises at least a first agent and a second agent. The first agent of the hair dye of the present invention contains urea to enhance the hair dyeing effect and the gray hair hiding effect.
The amount of urea in the first agent is preferably 1% by mass or more, and more preferably 4% by mass or more, based on the total amount of the first agent from the viewpoint of the hair dyeing effect and the gray hair hiding effect. The amount thereof is preferably 20% by mass or less, and more preferably 10% by mass or less from the viewpoint of the stability of the agent.
The first agent of the hair dye of the present invention comprises at least one selected from the group consisting of tannic acid, gallic acid, and a derivative thereof to enhance the hair dyeing effect and the gray hair hiding effect. Tannic acid, gallic acid, and a derivative thereof can each develop a color by reacting with the iron salt which the second agent described later comprises, and can fix the coloring element to the hair. The first agent may comprise one tannic acid or may comprise two or more tannic acids in combination. In addition, the first agent may comprise only one gallic acid or a derivative thereof or may comprise two or more gallic acids or their derivatives in combination. Furthermore, the first agent may comprise one, or two or more tannic acids, and one, or two or more gallic acids or their derivatives in combination.
Examples of the tannic acids include a hydrolyzable tannin and a condensed tannin. Examples of the hydrolyzable tannins include tannin derived from Rhus chinensis, gallnut, sumac, tara, chestnut, myrobalan, oak, divi-divi, algarobilla and Geranium thunbergii. Examples of the condensed tannin include tannin derived from gambier, quebracho, mimosa, mangrove, hemlock, spruce, Burma cutch, oak bark and persimmon.
Examples of the derivative of gallic acid include an alkyl ester of gallic acid. Examples of the alkyl ester of gallic acid include an ester of gallic acid with a linear or a branched alkyl having 1 to 10 carbon atoms, preferably an ester of gallic acid with a linear or a branched alkyl having 2 to 5 carbon atoms. Examples of the alkyl esters include ethyl gallate, propyl gallate and isoamyl gallate.
The tannic acid, gallic acid and a derivative thereof may be the one chemically synthesized using a known method or may be the one isolated from a plant. They may be a substance prepared by further performing chemical synthesis on gallic acid or a derivative isolated from a plant. Furthermore, an extract obtained from a plant containing tannic acid, gallic acid or a derivative thereof may be directly used.
For example, the gallic acid originated from tara that is a plant of the pea family, the gallic acid originated from gallnut produced by Chinese sumac of the sumac family, or an extract comprising any one of these may be used as gallic acid and a derivative thereof. A derivative which is obtained by chemically esterifying any one of the above gallic acids may be also used.
The amount of the compound selected from a group consisting of tannic acid, gallic acid and a derivative thereof in the first agent is not especially limited as long as the effects of the present invention can be achieved, but the amount is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, and yet more preferably 0.5 to 3% by mass based on the total amount of the first agent, from the viewpoint of the hair dyeing effect, the usability, and the stability of the agent.
The first agent of the hair dye of the present invention comprises at least one selected from the group consisting of a carbonate and a hydrogen carbonate, from the viewpoint that an excellent color tone is imparted to the hair after the hair dyeing. The first agent may comprise only the one compound selected from the group consisting of a carbonate and a hydrogen carbonate, or may include two or more compounds in combination selected therefrom.
Examples of the carbonates include sodium carbonate, potassium carbonate, ammonium carbonate, magnesium carbonate, barium carbonate and calcium carbonate. Examples of the hydrogen carbonate include sodium hydrogen carbonate, potassium hydrogen carbonate and ammonium hydrogen carbonate. It is preferable that the first agent comprises at least one selected from the group consisting of sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and ammonium hydrogen carbonate, from the viewpoint of the solubility in the first agent.
It is preferable that the first agent further comprises at least one benzophenone compound having two or more hydroxyl groups, from the viewpoint that an excellent color tone is achieved. Examples of the benzophenone compounds having two or more hydroxyl groups include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone disulfonic acid, 2,3,4-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, and 2,3,3',4,4',5-hexahydroxybenzophenone. From the viewpoint of the tendency to enhance the hair dyeing effect and the gray hair hiding effect, more preferably, the first agent comprises a benzophenone compound having three or more hydroxyl groups. Examples of the benzophenone compound having three or more hydroxyl groups include 2,3,4-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, and 2,3,3',4,4',5-hexahydroxybenzophenone. From the same viewpoint, more preferably, the first agent comprises a benzophenone compound having four or more hydroxyl groups.
It is preferable that the first agent of the hair dye of the present invention further comprises at least one selected from the group consisting of salicylic acid, polyhydric phenols other than the benzophenone compounds having two or more hydroxyl groups, and any of a derivative thereof, from the viewpoint that the range of the color tone is increased.
Examples of the derivatives of salicylic acid include esters and salts of salicylic acid. Examples of the esters of salicylic acid include an ester of salicylic acid with a linear or a branched alkyl having 1 to 10 carbon atoms, and a phenyl ester of salicylic acid. Specific examples of the esters include octyl salicylate, methyl salicylate, and phenyl salicylate.
Examples of the polyhydric phenols other than the benzophenone compounds having two or more hydroxyl groups, and their derivatives include hematein, pyrogallol, hematoxylin and catechol,
The amount of the compound selected from the group consisting of salicylic acid, the polyhydric phenol other than the benzophenone compounds having two or more hydroxyl groups, and their derivatives is not especially limited as long as the effects of the present invention can be achieved, but the amount is preferably 0.01 to 2% by mass, and more preferably 0.1 to 1% by mass based on the total amount of the first agent, from the viewpoint of the hair dyeing property.
The first agent of the hair dye of the present invention has pH of preferably 6.5 to 9.0 and more preferably 7.5 to 8.5. The fact that pH of the first agent is within the above ranges is advantageous, because the hair dyeing effect tends to be enhanced and the skin may scarcely be stimulated.
The second agent of the hair dye of the present invention comprises at least one iron salt to enhance the hair dyeing effect and the gray hair hiding effect. The iron salt develops a color by reacting with gallic acid, tannic acid, a derivative thereof, or the benzophenone compound having two or more hydroxyl groups which the hair dye optionally comprises, and can fix the coloring element to the hair.
The iron salt is not especially limited as long as the effects of the present invention can be achieved. Examples of the iron salt include ferrous sulfate, ferrous chloride, ferrous acetate, ferrous phosphate, ferrous oxalate, ferric sulfate, ferric chloride, and ferric acetate. From the viewpoint of the hair dyeing effect, it is preferable to use at least one iron salt selected from the group consisting of ferrous sulfate and ferrous chloride.
The second agent of the hair dye of the present invention may comprise one iron salt alone, or may comprise two or more iron salts in combination.
The amount of the iron salt in the second agent may be appropriately determined within a range in which the effects of the present invention are achieved, but the amount is preferably 0.5 to 10% by mass, and more preferably 1 to 6% by mass based on the total amount of the second agent, from the viewpoint of the hair dyeing effect.
The second agent of the hair dye of the present invention has pH of preferably 2 to 6, and more preferably 3 to 5, from the viewpoint of the stability of the agent.
In addition to the above components, the first agent and/or the second agent of the hair dye of the present invention may comprise other components used in ordinary hair dyes. Examples of such components include a base material, a surfactant, oils, a solvent, a thickener, an organic acid, a preservative, an antioxidant, a pH adjusting agent, a wetting agent, fragrance, a metallic smell masking agent, a coloring agent, an ultraviolet absorbing agent, a hair restorer/hair growth stimulant, an anti-dandruff agent, an antibacterial agent, a softener, a moisturizer, an active oxygen removing agent, an antioxidant, an antimicrobial agent, silicone, mineral, a protein hydrolysate, a peptide, an amino acid. The amounts of each of these components may be appropriately determined within a range in which the effects of the present invention are achieved.
Examples of the base include a higher alcohol, a hydrocarbon, a fatty acid ester, a vegetable oil, and a fatty acid.
In addition, the first agent of the hair dye of the present invention comprises preferably a higher alcohol, and more preferably at least one higher alcohol selected from the group consisting of cetostearyl alcohol, stearyl alcohol, cetyl alcohol and behenyl alcohol, from the viewpoint of the stability of the agent. The amount of the higher alcohol is preferably 1% by mass or more, and more preferably 3% by mass or more based on the total amount of the first agent, from the viewpoint of the stability of the agent and the usability. The amount is preferably 20% by mass or less, and more preferably 10% by mass or less, from the viewpoint of the usability.
Examples of the surfactant include an anionic surfactant, a non-ionic surfactant, an ampholytic surfactant and a cationic surfactant. Examples of the non-ionic surfactant include polyoxyethylene alkyl ether, polyoxyethylenepolyoxypropylene alkyl ether, a glycerin fatty acid ester, a polyglycerin fatty acid ester, a polyethyleneglycol fatty acid ester, and an alkyl glucoside. Examples of the anionic surfactant include a polyoxyethylene alkyl ether phosphate and a salt thereof, an N-acylamino acid salt, an alkyl ether carboxylate, an alkyl sulfate, a polyoxyethylene alkyl ether sulfate, and a sulfonate. Examples of the cationic surfactant include an alkylammonium salt. Examples of the ampholytic surfactant include alkylamidopropyl betaine.
In particular, the first agent of the hair dye of the present invention comprises preferably at least one non-ionic surfactant, and more preferably polyoxyethylene alkyl ether, from the viewpoint of the stability of the agent. From the same viewpoint, the amount of the non-ionic surfactant is preferably 0.1 to 10% by mass, and more preferably 1 to 7% by mass based on the total amount of the first agent.
Examples of the antioxidant include ascorbic acid and a derivative thereof, and sodium sulfite.
For example, citric acid, phosphoric acid, ammonia, ammonium hydrogen carbonate, ammonium bicarbonate, potassium hydroxide, sodium hydroxide, monoethanolamine, isopropanolamine, ammonium phosphate, diammoniummonohydrogen phosphate, sodium citrate, ammonium citrate, potassium phosphate, and sodium phosphate may be used as the pH adjusting agent.
Examples of the wetting agents include 1,3-butyleneglycol, propyleneglycol, glycerin, sorbitol, sodium pyrrolidone carboxylate, an amino acid and a vegetable oil.
Examples of the thickener include xanthane gum, polyethyleneglycol and hydroxyethyl cellulose.
Examples of the solvents include water, ethanol, isopropyl alcohol, 1,3-butyleneglycol, 1,2-pentanediol, 2-methyl-2,4-pentanediol, glycerin, diglycerin, propyleneglycol, dipropyleneglycol and benzyl alcohol.
The hair dye of the present invention comprises at least the first agent and the second agent, and may be a two-agent type hair dye consisting of the first agent and the second agent, may be a three-agent type hair dye consisting of the first agent, the second agent and additionally a third agent, or may be a multiple-agent type hair dye comprising more than three agents.
By mixing at least the first agent and the second agent of the present invention, dyeing the hair can be performed. As described later, the mixing may be carried out by applying the second agent to the hair after the first agent is applied to the hair, or may be carried out by mixing in advance the first agent and the second agent with each other. The mixing ratios of the first agent to the second agent (the first agent : the second agent) are preferably 1:0.5 to 1:2, more preferably 1:0.8 to 1:1.2, and yet more preferably 1:1 as the mass ratios, from the viewpoint of the hair dyeing effect.
The dosage forms of the first agent and the second agent which the hair dye of the present invention comprises may be a cream, a liquid, a gel, an emulsion, foam, a spray agent or an aerosol. The first agent and the second agent may have the same dosage form or may have dosage forms different from that of each other. It is preferable that the first agent is in a cream form or a gel form, from the viewpoint of the usability and the stability. It is preferable that the second agent is in a cream form or a gel form, from the viewpoint of the usability.
The preparation method of each of the first agent and the second agent which the hair dye of the present invention comprises is not especially limited and each of the agents can be produced using an ordinary method.
The hair can be dyed by applying to the hair the first agent and the second agent which the hair dye of the present invention comprises. Examples of the hair dyeing method include (i) a method of dyeing hair according to which the first agent is first applied to the hair, the hair is left for a predetermined time period, and then the second agent is applied to the hair without washing away the first agent, after that the hair is left for another predetermined time period, and the hair is thereafter washed off, (ii) another method of dyeing hair according to which the first agent and the second agent are concurrently applied to the hair, the hair is left for a predetermined time period, and then the hair is washed off, and (iii) yet another method of dyeing hair according to which a composition prepared by mixing the first agent and the second agent with each other is applied to the hair, the hair is left for a predetermined time period, and then the hair is washed off. It is preferable that the hair dyeing is performed using the method of the above (i), from the viewpoint of the hair dyeing effect.
The time period for hair dyeing after the application of the hair dye to the hair is appropriately adjusted according to the type and the amount of the gallic acid, tannic acid or a derivative thereof, the amount of the hair dye applied to the hair, and a desired degree of dyeing to be fixed. When the hair dyeing is performed using the method of the above (i) or (ii), the time period for hair dyeing after the application of the hair dye to the hair is generally 1 to 60 min and preferably 5 to 40 min after the application of the first agent, and is generally 1 to 60 min and preferably 5 to 40 min after the application of the second agent.
The amount of the first agent and the second agent to be applied is preferably about 30 to 70 g for the first agent and about 30 to 70 g for the second agent and more preferably about 40 to 60 g for the first agent and about 40 to 60 g for the second agent to the hair having a length of about 20 cm. In an embodiment of the present invention, 50 g of the first agent and 50 g of the second agent may be applied to the hair having a length of about 20 cm. The temperature during the application to the hair is 15 to 45°C, from the viewpoint of the physical burden for the hair and the human body.
The present invention will be described in more detail with reference to Examples below. The present invention is not limited by Examples.
(Preparation of First Agent)
The first agent was prepared as follows.
The oil phase components such as the surfactants, and the water phase components such as gallic acid, tannic acid or sodium salicylate, were separately weighed and were each sufficiently heated and dissolved. Thereafter, the water phase components were added to the oil phase components with sufficient stirring to emulsify them. Then, the obtained emulsion was cooled and the pH adjusting agent of the amount to adjust the pH of the first agent to 8 and urea dissolved into water were added thereto to obtain the first agent.
(Preparation of Second Agent)
The second agent was prepared as follows.
Ferrous sulfate or ferrous chloride was added to purified water at the normal temperature, and ascorbic acid was further added thereto. The obtained solution was stirred to dissolve the components to obtain the second agent. The obtained solution had pH of about 3.
(Hair Dyeing Effect and Color Tone of Hair)
2 g of the first agent according to the composition shown in Table 1 was applied to a hair bundle of 1 g (ratio of gray hair: 100%) which was treated with a shampoo and a conditioner and was sufficiently dried. Then, the hair bundle was left for 15 min at 30°C and at the relative humidity of 65%. After that, 2 g of the second agent according to the composition shown in Table 1 was applied to the hair bundle. The hair bundle was again left for 15 min at 30°C and at the relative humidity of 65%. The hair bundle was thereafter treated with a shampoo and a conditioner, and was dried using a dryer.
The hair dyeing effect and the color tone of the hair were evaluated on the dried hair bundle as follows.
The hair dyeing effect was evaluated with visual observation according to the following criteria by five professional panelists. When the evaluation of the five panelists was split into two, the evaluation supported by the majority was employed and, when the evaluation was split into three or more, the test and the evaluation were again conducted until the evaluations of the five all matched with each other or were split into two.
Evaluation Criteria for Hair Dyeing Effect
A: The hair was deeply and strongly dyed.
B: The hair was clearly dyed.
C: The hair was slightly dyed.
D: The hair was not dyed.
The color tone (especially, the strength of blue) of the hair was evaluated with visual observation according to the following criteria by the five professional panelists. When the evaluation of the five panelists was split into two, or three or more, the evaluation was made similarly to the above.
Evaluation Criteria for Color Tone of Hair
A: Blue was very weak.
B: Blue was weak.
C: Blue was somewhat strong.
D: Blue was very strong.
(Gray Hair Hiding Effect)
4 g of the first agent according to the composition shown in Table 1 was applied to a hair bundle of 2 g (ratio of gray hair: 20%) which was treated with a shampoo and a conditioner and was sufficiently dried. Then, the hair bundle was left for 15 min at 30°C and at the relative humidity of 65%. After that, 4 g of the second agent according to the composition shown in Table 1 was applied to the hair bundle. The hair bundle was again left for 15 min at 30°C and at the relative humidity of 65%. The hair bundle was thereafter treated with a shampoo and a conditioner, and was dried using a dryer.
The gray hair hiding effect was evaluated on the dried hair bundle as follows.
The gray hair hiding effect was evaluated with visual observation according to the following criteria by the five professional panelists. When the evaluation of the five panelists was split into two, or three or more, the evaluation was made similarly to the above.
Evaluation Criteria for Gray Hair Hiding Effect
A: No gray hair was conspicuous.
B: Gray hair was slightly conspicuous.
C: Gray hair was conspicuous.
D: No gray hair was dyed.
The hair dye of the present in which the first agent comprises the components (a) to (c) and the second agent comprises an iron salt achieved excellent results for the hair dyeing effect, the gray hair hiding effect, and the color tone. In contrast, the hair dyes according to Comparative Examples 1 to 8 each comprising another salt instead of (c) a carbonate or a hydrogen carbonate achieved no sufficient effects for the hair dyeing effect, the gray hair hiding effect, and the color tone.