JP2507926B2 - Method for producing black pigment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a black powder made of titanium oxynitride powder, which has high safety and can be manufactured at low cost, and is suitable for cosmetics.

[Prior Art and Problems] The present inventors have found a black titanium oxynitride powder (hereinafter, black titanium oxynitride powder) having a black color obtained by heating and reducing titanium dioxide with ammonia gas. It has been found that the cosmetics containing the compound (1) have good stability, excellent coloring power, are easy to use, and are easy to manufacture (JP-A-58-180413, JP-A-60-65069).

However, the titanium dioxide powder that is normally available contains ore as a raw material and some heavy metals derived from the manufacturing process (lead concentration is about 40 ppm to 80 ppm), and when reduced by heating in ammonia gas, the total amount of Since the weight is about 80 to 90% compared to the initial raw material weight, the content of heavy metals is relatively increased and it cannot be used for applications where safety is important (for example, cosmetics). There's a problem.

By the way, the allowable lead content of titanium dioxide specified in the cosmetics raw material standard is 50 ppm or less. On the other hand, titanium dioxide having a low content of heavy metals has a problem that the cost is high and the reaction (blackening) progresses slowly when heat reduction is performed in ammonia gas.

[Means for Solving Problems] The present inventors have found that when orthotitanic acid is used as a raw material in the production of the above-mentioned black titanium oxynitride, the primary particles are split during the reduction reaction, which leads to the lead existing inside the particles. It has been found that there is a possibility that a compound or the like becomes a hydrogen compound by the nascent hydrogen generated by thermal decomposition of ammonia gas at a high temperature and can be released to the outside of the system.

Furthermore, it was found that the consumption of ammonia gas used in the reduction reaction can be reduced by using the orthotitanic acid.

Based on the above findings, the present invention has achieved a method capable of inexpensively producing a highly safe black pigment of titanium oxynitride in which the content of heavy metals is greatly reduced by using orthotitanic acid as a raw material. .

[Structure of the Invention] According to the present invention, orthotitanic acid powder is heated in an ammonia gas atmosphere at a temperature of 600 to 900 ° C., and reduced until the blackness of the resulting powder is less than 13 in L value. A method for producing a black pigment is provided.

The present invention uses orthotitanic acid as a raw material for producing black titanium oxynitride. Orthotitanic acid can be easily obtained by, for example, boiling commonly available titanium dioxide or titanium hydroxide in an alkaline aqueous solution, thoroughly washing with water to remove salts, and then drying.

The orthotitanic acid is heated and reduced in an ammonia gas atmosphere. The heating temperature is suitably in the range of 600 to 900 ° C. If it is lower than 600 ° C, the reduction reaction does not proceed, and if it exceeds 900 ° C, particle growth due to sintering occurs, and the color tone becomes dark brown, which is not preferable.

The reason why the content of heavy metals decreases when orthotitanic acid is reduced by heating is not always clear.However, during the reduction reaction, the primary particles are split, and the lead compounds present inside the particles are separated by ammonia at high temperature. It is presumed that this is because hydrogen in the nascent stage generated by the thermal decomposition of gas becomes a hydrogen compound and is released to the outside of the system.

This phenomenon is not seen when other titanium dioxide or titanium hydroxide is used.

The degree of heat reduction is carried out until the blackness of the obtained powder becomes less than L value 13. When the L value is 13 or more, the splitting of the primary particles of orthotitanic acid does not proceed so much and the lead content is not reduced. The degree of reduction is the flow rate of ammonia gas,
It can be controlled by adjusting the reaction time and the reaction temperature.

The flow rate of ammonia gas varies depending on the amount of orthotitanic acid, but is 20 to 200 / min (per 6 Kg orthotitanic acid).
It is a degree.

[Effects of the Invention] The black titanium oxynitride powder of the present invention has a significantly reduced content of heavy metals, especially lead, as compared with conventional ones, and is highly safe as a raw material for cosmetics. Incidentally, the lead content of the titanium oxynitride obtained by the production method using the conventional titanium dioxide powder is about 70ppm ~ 190ppm, while the lead content of the one obtained by the production method of the present invention is about 5ppm ~ It is about 11 ppm, and the lead content is drastically reduced to about 1/10.

Further, according to the production method of the present invention using orthotitanic acid, the consumption amount of ammonia can be reduced to about 1/3 as compared with the conventional method using titanium dioxide powder.

[Example-1] Orthotitanic acid powder (manufactured by Tohoku Chemical Co., Ltd.) was heated at 800 ° C in ammonia gas, and the blackness of the obtained powder was L value 13
Reduced to less than. The reactor is JP-A-60-60924.
No. 30 cm in height and 100 cm in height, the flow rate of ammonia gas is 100 / min, the amount of orthotitanic acid is 6 kg,
5 lots were carried out. Table 1 shows the lead content in orthotitanic acid, the lead content of the titanium oxynitride powder obtained by reduction, the L value, and the ammonia basic unit.

[Comparative Example-1] A black pigment of titanium oxynitride powder was produced according to the same raw materials and conditions as in Example 1 except that the L value was 13 or more in the above reduction reaction. Table 2 shows the lead content of the raw material, the lead content of the titanium oxynitride powder, and the L value.

[Comparative Example-2] A black pigment of titanium oxynitride powder was produced under the same conditions as in Example 1 except that titanium dioxide powder (manufactured by Teikoku Kako Co., Ltd.) was used as a raw material. Table 3 shows the lead content, L value, and ammonia basic unit of the raw material and titanium oxynitride powder.

[Example 2] The black pigment obtained according to the present invention was mixed with a preservative in an appropriate amount according to the formulation shown in the following table, and talc was added to 100 parts to prepare an eye shadow.

[Example 3] A black pigment obtained by the present invention was mixed with a preservative, a fragrance and other colored pigments in an appropriate amount according to the formulation shown in the following table, and talc was added to 100 parts to prepare a solid white powder.

Claims (1)

(57) [Claims] 1. A black color obtained by heating orthotitanic acid powder in an ammonia gas atmosphere at a temperature of 600 to 900 ° C., and reducing the blackness of the resulting powder until the L value is less than 13. Method for producing pigment.