JP2006160718A - Makeup cosmetic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly safe makeup cosmetic obtained by using black magnetic particles used as a black pigment liquid, having excellent dispersion stability, and usable as the makeup cosmetic such as an eye liner and mascara by preventing the discoloration by oxidation. <P>SOLUTION: The makeup cosmetic is obtained by formulating the black magnetic particles covered with zinc oxide and having the surfactant adsorbed on the surfaces. The cosmetic is highly safe and has excellent dispersion stability. The discoloration of the cosmetic by the oxidation can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to makeup cosmetics. More specifically, the present invention relates to a makeup cosmetic that is excellent in dispersion stability of black magnetic particles and is prevented from being discolored by oxidation.

Conventionally used as a black pigment for makeup cosmetics is carbon black, black iron oxide, or the like. However, 3,4-benzpyrene, which is a carcinogenic substance, has been discovered from a type of carbon black, and there are strict regulations for use in cosmetics.

Next, when black iron oxide is used, the black iron oxide has a large particle diameter, and has a disadvantage that the specific gravity of the black iron oxide is large and easily settles with time.

In addition, a makeup cosmetic using a water-based magnetic fluid is known as a black iron oxide having a small particle size (Japanese Patent Laid-Open No. 1-224213). This product is black and stretches well and is popular as a makeup cosmetic.

However, black magnetic particles, mainly magnetite, used in magnetic fluids have the disadvantage that they are oxidized in air and turn reddish brown over time. In particular, when a cosmetic built-in type applicator is used, the specific surface area of the gas-liquid interface is increased because the padding is impregnated with a magnetic fluid, it is more easily oxidized, and the color changes quickly. Become.

In order to avoid such drawbacks, it has also been proposed to add a reducing substance, that is, an antioxidant so as to prevent oxidation and cause discoloration (JP-A-3-7213). If a large amount of the substance having the property is not added, the antioxidant effect cannot be obtained.

In addition, although it has been proposed to prevent discoloration by coating with resin (Japanese Patent Laid-Open No. 8-310916), there is a disadvantage that the blackness is lowered because it is coated with resin. In addition, there is a drawback in that aggregation due to polymerization occurs and the particles are likely to settle over time even when redispersed.
JP-A-1-242513 JP-A-3-7213

The problem to be solved by the present invention is a makeup cosmetic using black magnetic particles used as a black pigment solution, which has high safety, excellent dispersion stability, and prevents discoloration due to oxidation. Another object of the present invention is to provide a makeup cosmetic such as an eyeliner and a mascara.

As a result of intensive studies, the present inventors have found that the above object can be achieved by a makeup cosmetic containing black magnetic particles coated with zinc oxide and having a surface adsorbed with a surfactant. I found it.

By coating the surface of black magnetic particles as a black pigment liquid used as a makeup cosmetic with zinc oxide, the safety is high, the dispersion stability is excellent, and discoloration due to oxidation can be prevented. Therefore, this can be effectively used for makeup cosmetics such as eyeliner and mascara using a cosmetic built-in type applicator.

The black magnetic particles coated with zinc oxide used in the makeup cosmetics of the present invention include magnetite, manganese ferrite, cobalt ferrite, composite ferrite such as iron / cobalt ferrite, etc., and are generally produced by a coprecipitation method. What is used is used.

The black magnetic particles used in the present invention are spinel ferrite. Metal salts used for this spinel ferrite precipitation are sulfate, hydrochloride and nitrate. These are generally commercially available for industrial use.

Alkali hydroxide is used to precipitate spinel ferrite from the metal salt. Alkali hydroxide neutralizes a metal salt and precipitates a metal oxide, and also plays a role of pH adjustment for the metal oxide to precipitate as spinel ferrite.

Moreover, the primary particle size of the black magnetic particles is 50 nm or less. This is because when the size is 50 nm or more, the dispersion stability is deteriorated and sediments with time.

The amount of zinc oxide to be coated is such that a zinc salt aqueous solution corresponding to 1 to 50% by weight, preferably 2 to 35% by weight, more preferably 3 to 25% by weight of zinc oxide as zinc oxide is dropped into an alkaline aqueous solution. While maintaining the pH at 10 or higher, the mixture is stirred at 60 ° C. or higher for 30 minutes or longer to precipitate zinc oxide and coat it.

If the amount of zinc oxide is 1% by weight or less based on the black magnetic particles, the coating is insufficient and discoloration due to oxidation cannot be sufficiently prevented. If it is 50 parts by weight or more, the color tone as a black pigment cannot be maintained.

The zinc salt used in the present invention is prepared by dissolving zinc sulfate, zinc chloride, zinc nitrate or the like in water. The alkaline solution used in the present invention is prepared by dissolving a strong alkali such as sodium hydroxide, potassium hydroxide or lithium hydroxide in water.

The concentration of the aqueous zinc salt solution is preferably 0.01 mol / L to 10 mol / L. If it is 0.01 mol / L or less, the production efficiency is lowered, which is not preferable. Moreover, since reaction efficiency will fall when it is 10 mol / L or more, it is unpreferable.

As a method of adding the zinc salt aqueous solution, a method of continuously dropping in order to obtain a more uniform coating film thickness is preferable. If the addition is performed at once or at a high dropping rate, zinc oxide is precipitated before reaching the surface of the black magnetic particles, and zinc oxide not involved in coating is generated. Therefore, it is preferable to add the zinc salt aqueous solution at a rate that the dropping is completed within 30 minutes to 5 hours.

In order to improve the dispersion stability of the black magnetic particles coated with zinc oxide, a surfactant is adsorbed on the surface. As the surfactant, an anionic surfactant is preferable, and a higher fatty acid is particularly preferable.

Examples of the higher fatty acid include 8 to 30 carbon atoms, such as myristic acid, stearic acid, isostearic acid, oleic acid, linoleic acid, erucic acid, behenic acid, and naphthenic acid. These may be used alone or in combination of two or more. The amount of higher fatty acid used for surface adsorption is 5 to 70% by weight with respect to the black magnetic particles.

As an adsorption method, the alkaline acid of black magnetic particles coated with zinc oxide, in particular, a higher fatty acid metal salt is added to an aqueous suspension having a pH of 10 or more while stirring, and then the suspension is acidified, preferably adjusted to pH. By adjusting to 4 to 6, higher fatty acids are adsorbed on the surface of the black magnetic particles coated with zinc oxide.

The aqueous suspension in which higher fatty acids are adsorbed on the surface of the black magnetic particles coated with zinc oxide gradually settles when the stirring is stopped after cooling. Then, the particles are separated and filtered, washed to remove higher fatty acids not involved in adsorption, and dispersed in a solvent such as water or isoparaffin by a predetermined method to prepare a black pigment solution used as a makeup cosmetic. can do.

Hereinafter, examples will be given together with comparative examples to specifically describe a method for producing a black pigment liquid to be blended in the makeup cosmetic of the present invention.

(Example)
10.0 mol of sodium hydroxide is dissolved in 1000 ml of water. On the other hand, 1.0 mol of ferrous sulfate (FeSO ₄ .7H ₂ O) (effective 100%) and 1.0 mol of ferric sulfate liquid (Fe ₂ (SO ₄ ) ₃ ) (effective 41%) were added to 800 ml of water. Dissolve in The alkali solution was placed in a flask, the iron salt solution was added dropwise, heated to 80 ° C., and then aged for 60 minutes to obtain magnetite fine particles having an average particle diameter of 10 nm. Thereafter, a solution obtained by dissolving 0.1 mol of zinc sulfate (ZnSO ₄ .7H ₂ O) (effective 100%) in 1000 ml of water was dropped at a rate of 10 ml / min, followed by aging for 30 minutes to obtain a uniform coating of zinc oxide. A coating thickness was obtained. Thereafter, a solution of 80 g of sodium oleate dissolved in 500 ml of water was put into the flask, and then this suspension was dropped to adjust the pH of the aqueous solution of 30% sulfuric acid to 4 to 6 and coated with zinc oxide. Higher fatty acids were adsorbed on the surface of magnetite. After cooling, stirring was stopped and the agglomerated fine particles were filtered, washed with water, and finally dried to obtain magnetite fine particles coated with zinc oxide.
Next, 50 g of ion-exchanged water and 1.4 g of sodium oleate were added to 20 g of each of the obtained magnetite fine particles, and the mixture was stirred (9500 rpm, 30 minutes) and dispersed with an Ultra Turrax mixer to prepare a black pigment solution.

(Comparative Example 1)
In the examples, a black pigment solution of magnetite fine particles was prepared in the same manner except that zinc sulfate was not added.

(Comparative Example 2)
A black pigment solution of magnetite fine particles was prepared in the same manner except that sodium hydroxide was changed to 8.0 mol in the examples.

When these black pigment liquids were filled in a cosmetic built-in type applicator, left for one month in a high temperature bath at 50 ° C. and applied to the paper surface, Comparative Example 1 and Comparative Example 2 were initially What was black was discolored to brown, but those of the examples were not different from the initial black. That is, the effect of preventing discoloration was confirmed.

Claims (4)

A makeup cosmetic comprising black magnetic particles coated with zinc oxide, the particles having a surfactant adsorbed on the surface thereof. The makeup cosmetic according to claim 1, wherein the black magnetic particles include a spinel ferrite component of MOFe ₂ O ₃ and M is composed of one or more of Fe, Mn, Ni and Co. The makeup cosmetic according to claim 1, wherein the primary particle size of the black magnetic particles is 50 nm or less. The makeup cosmetic according to claim 1, wherein the zinc oxide is 5 to 90% by weight with respect to the black magnetic particles.