JP3395367B2 - Liquid colorant - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid colorant.
More specifically, the present invention relates to a liquid colorant effectively used in cosmetics and the like. 2. Description of the Related Art A makeup cosmetic using a magnetic fluid as a black iron oxide coloring agent is known (Japanese Patent Laid-Open No. 1-242513). In particular, a carcinogenic substance, 3,4-benzpyrene, has been discovered from a type of carbon conventionally used for eye lines and the like, and a water-based magnetic fluid has recently been receiving attention as an alternative material. The one using this water-based magnetic fluid has been popular as a makeup cosmetic because it is black, has good elongation, and has an effect of absorbing ultraviolet rays. [0003] However, whether the black iron oxide coloring agent is a magnetic fluid or a commercially available dispersed type ultrafine black iron oxide, the black iron oxide is generally oxidized by oxygen in the air,
Because it has the property of changing to red iron oxide over time,
It has been proposed to allow a reducing substance to coexist there (JP-A-3-7213). However, simply adding a reducing substance to a liquid coloring material containing a black iron oxide coloring agent and a solvent also reduces the surface of the black iron oxide, and the color of the surface is higher than the initial color. Further, a problem of blackening occurs. Conversely, the state in which the reduction is performed can be used as the initial color, but in this case, oxidation occurs over time, and it is unavoidable that the same discoloration as when no reducing substance is used occurs. . SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid colorant containing a black iron oxide colorant, a reducing substance, and a solvent, to give the black colorant stability over time. Is to provide things. SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by using the liquid colorant in a state where a reducing substance is encapsulated in microcapsules. As the black iron oxide colorant, when the application of the liquid colorant is a cosmetic or the like, a water-based magnetic fluid is preferably used. As the water-based magnetic fluid, a wet-process magnetite magnetic fluid for producing magnetite by adding an aqueous solution of NaOH or an aqueous solution of NH _{3 to an} aqueous solution of a mixture of a ferrous salt and a ferric salt is generally used. In addition to the magnetic fluid, as long as the iron oxide shows black, commercially available ultrafine iron oxide particles of a dispersion type can be used, and the smaller the particle size, the more preferable. Examples of the solvent include various organic solvents other than water, such as alcohols, polyols, ketones, and ethers, depending on other uses of the liquid colorant, for example, various uses such as pigments, paints, and printing. , Aliphatic, alicyclic or aromatic hydrocarbons, squalene, castor oil, cottonseed oil, liquid lanolin, liquid paraffin, and the like. The black iron oxide coloring agent is used by being added to these solvents at a ratio of about 2 to 55% by weight, preferably 17 to 51% by weight. Examples of the reducing agent include (1) alkali metal salts of inorganic acids such as thiosulfuric acid, sulfurous acid, bisulfite, pyrosulfite, and hypophosphorous acid; (2) vanillin, eugenol, isoeugenol, gallic acid and the like. Its alkyl esters,
(3) hydroquinone, catechol, resorcin, resorcin acetate, hydroxyl-containing aromatic compounds such as butylated hydroxyanisole, (4) pyridoxine, pyridoxal,
A hydroxyl group-containing heterocyclic compound such as pyridoxal phosphate,
(5) glucose, lactose, hemiacetal hydroxyl-containing sugars such as fructose, (6) at least one of organic acids such as ascorbic acid, citric acid, kojic acid, sorbic acid or alkali metal salts thereof, black iron oxide color It is used in a proportion of about 0.1 to 10% by weight, preferably about 0.4 to 4% by weight, based on the amount of the solvent solution of the agent. [0010] These reducing agents are used in a state of being encapsulated in microcapsules. The encapsulation of the reducing agent in the microcapsules can be performed by any method, for example, by an interfacial polymerization method, an in situ polymerization method, a liquid curing coating method, a coacervation method, a spray drying method, an inorganic wall method, or the like. Done. Such microencapsulation makes the reducing agent exhibit a sustained release property, but the method proposed by the present applicant for controlling the sustained release rate, that is, a sustained release substance and polyethyleneimine Is added to the diisocyanate solution to form microcapsules containing an aqueous solution of the controlled release substance by an interfacial polymerization method. Heat treatment in an aqueous solution is also effective (Japanese Patent Publication No. 6-9650). The preparation of the composition is carried out by adding microcapsules encapsulating a reducing substance to a solvent solution of black iron oxide. When black iron oxide is used as an aqueous solution (aqueous dispersion), 1,3-butylene glycol or the like is added to the aqueous solution as a wetting agent in addition to the surfactant. According to the present invention, in a liquid colorant containing a black iron oxide colorant, a reducing substance and a solvent, the reducing substance is encapsulated in microcapsules and used as a sustained-release reducing substance. It is possible to effectively prevent the color of the colorant from changing over time. Next, the present invention will be described by way of examples. Example 1 After ethyl cellulose was added to and dissolved in heated cyclohexane, polyisobutylene as a phase separating agent and ascorbic acid as a reducing agent were added to the cyclohexane solution, and the mixture was cooled while stirring and sealed with ascorbic acid. Microcapsules (particle size: about 200 μm, ascorbic acid content: about 90%) were obtained. The ascorbic acid-encapsulated microcapsules were mixed with black iron oxide (spherical magnetite having an average diameter of 10 nm) of 20 weight
%, Sodium dodecylbenzenesulfonate 3% by weight, 1,3
-An aqueous colorant was prepared by adding 5% by weight of butylene glycol and 72% by weight of pure water to a black iron oxide colorant solution such that the amount of ascorbic acid was 5% by weight based on the amount of the solution. The prepared aqueous colorant was impregnated into a pen containing batting and left in a constant temperature bath at 52 ° C. for 4 weeks, after which letters were drawn on paper, but the color was almost unchanged from the initial color. No discoloration was observed. Comparative Example In the examples, ascorbic acid not encapsulated in microcapsules was used. After standing at 52 ° C. for 4 weeks, the color of the letters drawn by the aqueous colorant was considerably redder than the initial color.

Continuation of front page (56) References JP-A-3-7213 (JP, A) JP-A-7-96166 (JP, A) JP-A-2-88514 (JP, A) JP-A-7-324015 (JP) JP-A-4-74116 (JP, A) JP-A-53-75341 (JP, A) JP-B-6-9650 (JP, B2) JP-T-2-503000 (JP, A) International publication 91 / 1801 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61K ^7/ 00-7/032

Claims (1)

(1) A colorant containing a black iron oxide coloring agent, a reducing substance and a solvent, wherein the reducing substance is used by being encapsulated in microcapsules. .