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Zinc oxide powder aggregates present in circular, ellipsoidal, linear and branched form

A technology of zinc oxide powder and aggregate, applied in the direction of zinc oxide/zinc hydroxide, fibrous filler, etc., can solve the problem of adding such particles to sunscreen preparations

Inactive Publication Date: 2009-04-22
EVONIK DEGUSSA GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is often difficult to incorporate such particles into sunscreen formulations

Method used

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  • Zinc oxide powder aggregates present in circular, ellipsoidal, linear and branched form
  • Zinc oxide powder aggregates present in circular, ellipsoidal, linear and branched form
  • Zinc oxide powder aggregates present in circular, ellipsoidal, linear and branched form

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0073] Example 1 was carried out in a reactor according to FIG. 4 .

[0074] Through nitrogen flow (4.2Nm 3 / h) Feed zinc powder (510g / h) into it to burn hydrogen / air flame (hydrogen: 4.0Nm 3 / h, air: 8.0Nm 3 / h) in the reducing evaporation zone. Zinc dust is thereby evaporated.

[0075] A reaction mixture including zinc vapor, hydrogen, nitrogen and water is injected into the oxidation zone, to which 20Nm 3 / h of air.

[0076] The temperature T1 before the addition of oxidizing air was 956°C. Then, add 10Nm 3 / h of quench air. The temperature T2 before the addition of quench air was 648°C. The resulting zinc oxide powder is separated from the gas stream by filtration.

[0077] Examples 2 to 4 were carried out analogously to example 1. The process parameters are shown in Table 1.

Embodiment 5

[0078] Embodiment 5 (comparative example)

[0079] Through nitrogen flow (1.5Nm 3 / h) Feed zinc powder (250g / h) into a flame where hydrogen / air is burned (hydrogen: 4.25Nm 3 / h, air: 8.40Nm 3 / h) in the evaporation zone. Zinc dust is thereby evaporated.

[0080] Then, by metered addition of 1Nm 3 Nitrogen per h cools the reaction mixture comprising zinc vapor, hydrogen, nitrogen and water to a temperature of 850° C. in the nucleation zone. Then add 5m 3 / h of oxidizing air and 34Nm 3 / h of quenching air, the reaction temperature drops to a temperature below 400°C. The resulting zinc oxide powder is separated from the gas stream by filtration.

[0081] Example 5 can be referred to the patent application DE 10212680 filed on March 22, 2002.

Embodiment 6

[0082] Embodiment 6 (comparative example) is from Nanophase, Zinc oxide powder commercially available at Zinc Oxide 99+%.

[0083] The preparation process parameters of the zinc oxide powders of Examples 1 to 4 are shown in Table 1. Table 2 shows the physicochemical data of the zinc oxide powders of Examples 1 to 6.

[0084] Table 2 shows that the powders of Examples 1 to 4 according to the invention exhibit the claimed distribution of aggregates forming circular, linear, branched and elliptical morphologies. Comparative Examples 5 and 6 did not exhibit this distribution.

[0085] The powders of Examples 1 to 4 according to the invention have an equicircular diameter of less than 100 nanometers, an average aggregate perimeter of less than 600 nanometers, and an average aggregate surface area of ​​less than 7500 square nanometers.

[0086] Figure 3a -d represents the linear, branched, elliptical and circular aggregates of the powder of Example 3, respectively.

[0087] ...

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Abstract

Pyrogenically prepared zinc oxide powder having a BET surface area of from 10 to 200 m / g, which is in the form of aggregates, the aggregates being composed of particles having different morphologies, and 0-10 % of the aggregates being in a circular form, 30-50 % being in an ellipsoidal form, 30-50 % being in a linear form and 20-30 % being in a branched form. It is prepared by reacting a starting mixture containing zinc vapour, a combustible gas and steam or a mixture of steam and carbon dioxide in a flame with an oxygen-containing gas in an oxidation zone, cooling the hot reaction mixture in a quenching zone and separating the solid material from the gas stream, the amount of oxygen in the oxidation zone being greater than the amount necessary for the complete oxidation of the combustible gas and the zinc vapour. The zinc oxide powder can be used as a constituent of sun protection compositions for protection against UV radiation.

Description

technical field [0001] The present invention relates to zinc oxide powder and its preparation and use. Background of the invention [0002] Zinc oxide powder is used in inks, surface coatings, resins and fibers. In the field of cosmetics, especially as an ingredient in sunscreen formulations, the use of zinc oxide powders is an important aspect. [0003] In principle, there are two possible processes for the synthesis of zinc oxide powder: wet chemical method and gas phase method. Generally, zinc compounds used as raw materials in wet chemical methods are compounds that can be converted into zinc oxide by heating, such as zinc hydroxide, zinc oxalate, or zinc carbonate. Wet chemical methods generally have the disadvantage of agglomerating the zinc oxide particles, forming larger units, which is undesirable especially in cosmetic applications. In addition, impurities from the synthesis process and raw materials cannot or are extremely difficult to remove from the final pro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09C1/04C01G9/03
CPCC09C1/043C01G9/03C01P2004/04C01P2006/11
Inventor 斯蒂潘·卡图希奇米夏埃尔·克雷默彼得·克雷斯霍斯特·米斯吉多·齐默尔曼彼得·阿尔贝斯
Owner EVONIK DEGUSSA GMBH
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