Tin-containing indium oxides, a process for producing them, a coating solution using them and electrically conductive coatings formed of them

• US 6,908,574 B2
• Filed: 03/28/2002
• Issued: 06/21/2005
• Est. Priority Date: 08/13/2001
• Status: Active Grant

• Current Assignee: Dowa Mining Company Limited
• Original Assignee: Dowa Mining Company Limited
• Inventors: Horikawa, Yoshichika, Eshima, Kohichiro, Moteki, Yoshio, Inamura, Tatsumi
• Primary Examiner(s): Kopec, Mark
• Application Number:
  US10/108,618
• Publication Number:
  US 20030030036A1
• Time in Patent Office: 1,181 Days
• Field of Search: 252/500, 252/518, 252/520, 252/503, 252/518.1, 252/520.1, 423/89, 423/111, 423/618, 423/624, 428/357, 428/364, 428/212, 428/323, 502/355
• US Class Current: 252/518.1
• CPC Class Codes: C01G 19/00 Compounds of tin
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: H01B 1/08 oxides

Abstract

A Sn-containing In oxide in the form of needles or plates comprising particles having a major axis of 0.1 μm or less and a minor axis of 0.05 μm or less.

Claims

1. A Sn-containing In oxide in the form of needles or plates comprising particles having a major axis of 0.1 μ

m or less and a minor axis of 0.05 μ

m or less.

2. The Sn-containing In oxide according to claim 1, wherein the particles have a major-to-minor axis ratio of 1.5-10.

3. The Sn-containing In oxide according to claim 2, wherein the major-to-minor axis ratio is 2 to 5.

4. A coating solution comprising the particles of the Sn-containing In oxide according to claim 1 dispersed in a solvent or a resin-containing solvent.

5. A coating solution comprising the particles of the Sn-containing In oxide according to claim 2 dispersed in a solvent or a resin-containing solvent.

6. In an electrically conductive coating including a conductive material, the improvement comprising the conductive coating containing the particles of the Sn-containing In oxide according to claim 1 as the conductive material.

7. In an electrically conductive coating including a conductive material, the improvement comprising the conductive coating containing the particles of the Sn-containing In oxide according to claim 2 as the conductive material.

8. A process for producing the Sn-containing In oxide according to claim 1 which comprises the steps of:

(a) preparing an acidic aqueous solution containing Sn and In,

(b) adding a first portion of an alkali to the acidic aqueous solution at a temperature of the solution of 40°

C. or below to prepare a preliminarily neutralized aqueous solution,

(c) raising the temperature of the preliminarily neutralized aqueous solution from step (b),

(d) adding a second portion of said alkali to the aqueous solution from step (c) at a temperature of the solution of 50°

C. or above to prepare a fully neutralized solution, and forming Sn-containing In hydroxide particles, and

(e) firing the Sn-containing In hydroxide particles from step (d).

9. The process according to claim 8, wherein the acid in said acidic aqueous solution is HCl, HNO₃ or H₂SO₄ and said alkali is NH₄OH, NaOH or KOH.

10. The process according to claim 8, wherein the preliminarily neutralized solution has a pH of 2-4 and the fully neutralized solution has a pH of 7-8.

11. The process according to claim 8, wherein said firing is performed in an inert gas containing water vapor or both water vapor and a reducing gas at 300-1,000°

C. while maintaining the shape anisotropy of the particles of said Sn-containing In hydroxide.

12. The process according to claim 8, wherein the temperature of the solution in step (b) is 25°

C. or below.

13. The process according to claim 8, wherein the temperature of the solution in step (d) is 80 to 95°

C.

14. The process according to claim 12, wherein the temperature of the solution in step (d) is 80 to 95°

C.

15. A transparent conductive film forming ITO powder comprising (i) acicular ITO particles having a major axis of 0.1 μ

m or less, a minor axis of 0.05 μ

m or less, a major-to-minor axis ratio of 1.5-10 and a SnO₂ content of 2-20 wt %, and (ii) granular ITO particles having a grain size of 0.05 μ

m or less and a SnO₂ content of 2-20 wt %.

16. The transparent conductive film forming ITO powder according to claim 15, wherein the weight ratio of said acicular ITO particles to said granular ITO particles is in the range of from 2:

98 to 98;

2.

17. The transparent conductive film forming ITO powder according to claim 16, wherein the weight ratio is 5:

95 to 50;

50.

18. The transparent conductive film forming ITO powder according to claim 16, wherein the weight ratio is 5:

95 to 30;

70.