Method for manufacturing hexagonal plate-shaped zinc oxide particles

Patent metadata

Field	Value
Publication number	US-10093550-B2
Application number	US-201615336937-A
Country	US
Kind code	B2
Filing date	Oct 28, 2016
Priority date	May 1, 2014
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A method of producing hexagonal plate-like zinc oxide particles having a sharp particle size distribution (i.e., a relatively uniform particle size) at a high weight yield and a high percent yield is provided. The method of producing hexagonal plate-like zinc oxide particles of the present invention comprises mixing by stirring an aqueous hexamethylenetetramine (HMT) solution, a solution of an anionic surfactant in a water-insoluble organic solvent, and optionally water to form a microemulsion containing an aqueous phase of an aqueous hexamethylenetetramine solution having a molar concentration of 0.05 M or more; dropwise adding an aqueous zinc salt solution to the microemulsion; and heating the microemulsion containing the aqueous zinc salt solution to a reaction temperature of 80° C. or more without using any autoclave to form hexagonal plate-like zinc oxide particles.

First claim

What is claimed is:

1. A method of producing hexagonal plate-like zinc oxide particles, comprising:
mixing by stirring an aqueous hexamethylenetetramine (HMT) solution; and a solution of an anionic surfactant in a water-insoluble organic solvent to form a microemulsion containing an aqueous phase of an aqueous hexamethylenetetramine solution having a molar concentration of 0.05 M or more;
dropwise adding an aqueous zinc salt solution to the microemulsion; and
heating the microemulsion containing the aqueous zinc salt solution to a reaction temperature of 80° C. or more without using any autoclave to form hexagonal plate-like zinc oxide particles.

2. The method according to claim 1 , wherein the molar concentration ratio of the aqueous hexamethylenetetramine solution to the aqueous zinc salt solution in the microemulsion is within a range of 0.5 to 1.0.

3. The method according to claim 1 , wherein the reaction temperature is raised at a rate of 5° C./min or less.

4. The method according to claim 1 , wherein the aqueous zinc salt solution is dropwise added over 2 minutes or more.

5. The method according to claim 1 , wherein the microemulsion is maintained at the reaction temperature for 1 hour or more.

6. The method according to claim 1 , wherein the microemulsion contains the aqueous hexamethylenetetramine solution at a molar concentration of 0.5 M or more and the aqueous zinc salt solution at a concentration of 0.8 M or more.

7. The method according to claim 1 , wherein the zinc salt is zinc nitrate.

8. The method according to claim 1 , wherein the anionic surfactant is sodium di(2-ethylhexyl)sulfosuccinate (AOT).

9. The method according to claim 1 , wherein the water-insoluble organic solvent is 1-butanol.

10. The method according to claim 1 , further comprising:
separating, drying, and/or heat treating the hexagonal plate-like zinc oxide particles.

11. The method according to claim 1 , wherein the hexagonal plate-like zinc oxide particles have a volume average particle diameter D50 of 0.70 to 2.00 μm.

12. The method according to claim 1 , wherein the hexagonal plate-like zinc oxide particles have a particle size distribution represented by a ratio D90/D10 of 4.00 or less.

13. The method according to claim 1 , wherein the mixing further includes water to form the microemulsion.

Assignees

• Ngk Insulators Ltd
• Nagoya Inst Tech

Inventors

• Yoshikawa Jun
• Nanataki Tsutomu
• Hayakawa Tomokatsu

Classifications

• C01P2004/51

  Particles with a specific particle size distribution · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2002/50

  Solid solutions · CPC title

• C01P2002/52

  containing elements as dopants · CPC title

• A61Q19/00

  Preparations for care of the skin · CPC title