Metal oxide particles and method of producing the same

Patent metadata

Field	Value
Publication number	US-2018179060-A1
Application number	US-201615759309-A
Country	US
Kind code	A1
Filing date	Jun 3, 2016
Priority date	Oct 5, 2015
Publication date	Jun 28, 2018
Grant date	—

Abstract

A method of producing efficiently and stably core-shell type oxide particles, wherein the entire surface of the core oxide particles is uniformly coated with the shell oxide, includes at least two steps of: Step 1 of precipitating the core oxide particles in a mixed fluid prepared by mixing an oxide raw material liquid for core and an oxide precipitation solvent and Step 2 of coating the entire surface of the core oxide particles uniformly with the shell oxide by mixing the mixed fluid and an oxide raw material liquid for shell. (A) At least Steps 1 and 2 are performed continuously between at least two processing surfaces 1 and 2 which are capable of approaching to and separating from each other, at least one of which rotates relatively to the other; (B) after Step 1, Step 2 is completed within a prescribed time during which the core oxide particles do not aggregate in the mixed fluid; or (C) Step 1 and Step 2 are controlled so that the primary particle diameter of the core-shell type oxide particles is 190% or less relative to the primary particle diameter of the core oxide particles.

First claim

1 . A method of producing core-shell type oxide particles wherein the surface of the core oxide particles are coated with the shell oxide, comprising at least two steps of:
Step 1 of precipitating the core oxide particles in a mixed fluid prepared by mixing an oxide raw material liquid for core containing at least an oxide raw material for core which is a raw material of the core oxide particles, and an oxide precipitation solvent containing at least an oxide precipitation substance for precipitating the core oxide particles; and Step 2 of coating the entire surface of the core oxide particles uniformly with the shell oxide by mixing the mixed fluid and an oxide raw material liquid for shell containing at least a shell oxide raw material which is a raw material of the shell oxide; and wherein the at least two steps are performed continuously between at least two processing surfaces which are capable of approaching to and separating from each other, at least one of which rotates relatively to the other.

2 . The method of producing core-shell type oxide particles according to claim 1 wherein after Step 1, Step 2 is completed within a prescribed time during which the core oxide particles do not aggregate in the mixed fluid.

3 . The method of producing core-shell type oxide particles according to claim 2 , wherein the prescribed time is within 1 second.

4 . The method of producing core-shell type oxide particles according to claim 1 wherein Step 1 and Step 2 are controlled so that the primary particle diameter of the core-shell type oxide particles is 190% or less relative to the primary particle diameter of the core oxide particles.

5 . (canceled)

6 . The method of producing core-shell type oxide particles according to claim 1 ,
wherein the center side of the at least two processing surfaces is disposed at an upstream side and the outside is disposed at a downstream side; either one of the oxide raw material liquid for core and the oxide precipitation solvent as the first fluid passes from the upstream side to the downstream side between the at least two processing surfaces, while forming a thin film fluid; the other of the oxide raw material liquid for core and the oxide precipitation solvent as the second fluid is introduced into the space between the at least two processing surfaces from an opening formed on at least either one of the at least two processing surfaces through the second passage independent from the first passage which the first fluid is introduced into the space between the at least two processing surfaces through, and then the oxide raw material liquid for core and the oxide precipitation solvent are mixed between the at least two processing surfaces to precipitate the core iron oxide particles; the oxide raw material liquid for shell is introduced into the space between the at least two processing surfaces from an opening formed on at least either one of the at least two processing surfaces through the third passage independent from the first passage and the second passage; and the opening of the second passage is provided at the upstream side of the opening of the third passage.

7 . The method of producing core-shell type oxide particles according to claim 6 , wherein the following equations are satisfied:
F 1 >F 2 and F 1 +F 2> F 3
wherein F 1 is a flow rate of the first fluid introduced in the space between the at least two processing surfaces, F 2 is a flow rate of the second fluid introduced in the space between the at least two processing surfaces, and F 3 is a flow rate of the third fluid introduced in the space between the at least two processing surfaces.

8 . The method of producing core-shell type oxide particles according to claim 1 , wherein the core oxide particles are zinc oxide particles or iron oxide particles, and the shell oxide is silicon oxide.

9 . The method of producing core-shell type oxide particles according to claim 8 , wherein the core oxide particles are zinc oxide particles, and thickness of the shell oxide is 0.01% to 60% relative to the diameter of the core-shell type oxide particles.

10 . The method of producing core-shell type oxide particles according to claim 8 , wherein the core oxide particles are zinc oxide particles, and
after irradiating a ultraviolet light of 365 nm for at least 2 hours to a dispersion containing methylene blue dye in which the core-shell type oxide particles are dispersed, an attenuation rate of absorbance derived from methylene blue dye for a light of a wavelength of around 660 nm is 10% or less.

11 . The method of producing core-shell type oxide particles according to claim 8 , wherein the core oxide particles are iron oxide particles, and thickness of the shell oxide is 0.5% to 25% relative to the diameter of the core-shell type oxide particles.

12 . The method of producing core-shell type oxide particles according to claim 8 , wherein the core oxide particles are iron oxide particles, and
after irradiating a white light for at least 2 hours to a dispersion containing Congo red dye in which the core-shell type oxide particles are dispersed, an attenuation rate of absorbance derived from Congo red dye for a light of a wavelength of around 505 nm is 10% or less.

13 . The method of producing core-shell type oxide particles according to claim 1 , wherein the shell oxide contains an element different from an element contained in the core oxide particles.

14 . A core-shell type oxide particles wherein the entire surface of the core oxide particles is uniformly coated with a shell oxide,
wherein the core oxide particle is one single zinc oxide particle, and the shell oxide is a silicon oxide, and thickness of the shell oxide is 0.01% to 60% relative to the diameter of the core-shell type oxide particles, or wherein the core oxide particle is one single iron oxide particle, and the shell oxide is a silicon oxide, and thickness of the shell oxide is 0.5% to 25% relative to the diameter of the core-shell type oxide particles.

15 . (canceled)

16 . A silicon oxide-coated iron oxide composition for coating, containing iron oxide particles wherein at least a part of the surface of the iron oxide particles is coated with a silicon oxide, wherein reflectance for a light of a wavelength of 400 to 620 nm is less than 18%, and a primary particle diameter of the iron oxide particles is 1 to 50 nm.

17 . The silicon oxide-coated iron oxide composition for coating according to claim 16 , wherein transmittance of a dispersion containing the iron oxide particles for a light of a wavelength of 200 to 420 nm is 2.0% or less, and transmittance of the dispersion for a light of a wavelength of 620 to 800 nm is 80% or more.

18 . The silicon oxide-coated iron oxide composition for coating according to claim 16 , wherein haze value of a dispersion containing the iron oxide particles is 2.0% or less at the concentration of 2 wt % of the iron oxide in the dispersion.

19 . The silicon oxide-coated iron oxide composition for coating according to claim 16 , wherein the silicon oxide is amorphous.

20 . The silicon oxide-coated iron oxide composition for coating according to claim 16 , which is a weather resistant composition for coating which is blended and used in a coating material constituting a coated body, and has prescribed reflectance, transmittance and transparency, and protects the coated body from an ultraviolet light,
wherein the weather resistant composition comprises core-shell type iron oxide particles wherein the

Assignees

• M Technique Co Ltd

Inventors

• Enomura Masakazu
• Honda Daisuke

Classifications

• C09C1/043

  Zinc oxide · CPC title

• C09D1/00

  Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• C01G9/02

  Oxides; Hydroxides · CPC title

• A61K2800/651

  The particulate/core comprising inorganic material · CPC title