Thermally stable color pigments with nanofiber coating

Patent metadata

Field	Value
Publication number	US-10487212-B2
Application number	US-201715813172-A
Country	US
Kind code	B2
Filing date	Nov 15, 2017
Priority date	Feb 6, 2017
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A method to coat oxide-based color pigments with an ultrasound-assisted coating of nanofiber or other nanostructures in order to enhance heat-fastness and color performance to said color pigments is presented. In particular, the present invention provides a method to coat oxide-based color pigments with nano-coating materials, including but not limited to, alumina and/or silica at different dosage levels, with nanospike, nanoneedle, nanoplate, and/or nanoflower morphology towards enhancing the heat-fastness and color performance of said color pigments.

First claim

What is claimed is:

1. A method of increasing the thermal stability of iron oxide pigments comprising:
placing iron oxide pigment in a coating material precursor solution, wherein the coating material precursor solution is a precursor of one or more of aluminum oxide and silicon oxide;
treating the iron oxide pigment and the coating material precursor solution with ultrasound at a temperature of less than 100° C. to promote nanoparticle formation on the iron oxide pigment; and
growing a coating from the coating material precursor solution to grow nanoparticles of one or more of the aluminum oxide and the silicon oxide on a surface of the iron oxide pigment such that the resulting iron oxide pigment is thermally stable to a temperature of at least 230° C.;
wherein the ultrasound treatment occurs at a frequency where the ultrasound wavelength is approximately an integral multiple of a rod length of the iron oxide pigment with one of the treatment frequencies being between approximately 40 and 55 kHz;
wherein the rod length is 714.3±137.5 nm.

2. The method according to claim 1 , wherein the aluminum oxide precursor is an aluminum sulphate.

3. The method according to claim 1 , wherein the silicon oxide precursor is tetraethylorthosilicate or aminopropyl triethylsilane.

4. The method according to claim 1 , wherein the iron oxide pigment is FeOOH yellow iron oxide.

5. The method according to claim 1 , wherein the nanoparticles are selected from nanofiber or nanoneedle.

6. The method according to claim 1 , wherein the ultrasound treatment is applied for a period of approximately 5 minutes to 120 minutes.

7. The method according to claim 1 , wherein the temperature during ultrasound treatment is approximately 40-80° C.

8. The method according to claim 1 , wherein the pH during the ultrasound treatment is controlled to between approximately 7-8.

9. The method according to claim 1 , wherein the ultrasound-treated material is aged for a period of between approximately 5 minutes and approximately 240 minutes.

10. The method according to claim 1 , wherein the ultrasound treatment occurs at 45 kHz.

11. The method according to claim 1 , wherein the ultrasound treatment occurs at a frequency where the ultrasound wavelength is approximately an integral multiple of a rod length of the iron oxide pigment.

Assignees

• Univ Hong Kong Baptist Univ

Inventors

• Leung Cham Fai
• Yick Chung Yan

Classifications

• C01B33/113

  Silicon oxides; Hydrates thereof {(preparing monoxide by reduction of siliceous material C01B33/182)} · CPC title

• C01F7/02

  Aluminium oxide; Aluminium hydroxide; Aluminates · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01P2002/88

  by thermal analysis data, e.g. TGA, DTA, DSC · CPC title