Electroconductive powder and method for production thereof

• US 7,407,606 B2
• Filed: 07/22/2004
• Issued: 08/05/2008
• Est. Priority Date: 07/23/2003
• Status: Expired due to Fees

• Current Assignee: Ishihara Sangyo Kaisha Limited
• Original Assignee: Ishihara Sangyo Kaisha Limited
• Inventors: Yasuda, Yuichi, Chiba, Katsuichi
• Primary Examiner(s): Kopec; Mark
• Assistant Examiner(s): Nguyen; Khanh Tuan
• Application Number:
  US10/565,244
• Publication Number:
  US 20060208228A1
• Time in Patent Office: 1,475 Days
• Field of Search: 252/500, 252/518.1, 252/520.1, 252/519.33, 430/111.1, 428/336, 428/378, 106/417, 106/436, 106/437, 106/438, 427/215, 524/104
• US Class Current: 252/520.1
• CPC Class Codes: C01G 23/00 Compounds of titanium preparation of Ti-compounds from ores or scraps C22B34/12
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C09C 1/3661 Coating
• CPC Class Codes: H01B 1/08 oxides

Abstract

A method for producing a titanium dioxide powder having a well electroconductive layer containing substantially no antimony, which comprises providing a titanium dioxide powder containing specific amounts or less of alkali metals, such as sodium and potassium, alkaline earth metals, such as magnesium and calcium, and metals having a valence of four or less, such as aluminum, zinc and iron, preparing an aqueous suspension of the titanium dioxide powder, adding an acidic aqueous solution containing a tin compound and a phosphorus compound and an alkaline solution to the above aqueous suspension so that the aqueous suspension has a pH in the range of 2 to 6 or 8 to 12, and firing the resulting product at a temperature of 600 to 925° C.

Claims

1. A method for producing an electroconductive powder which comprises adding an aqueous acidic solution in which a tin compound and a phosphorus compound are dissolved and an aqueous alkaline solution to an aqueous suspension of titanium dioxide in which the content of a metallic element having a valence of 4 or less contained in the titanium dioxide as an impurity is 0.02 or less as (B) obtained by the following formula (2)

(B)=(M′

₁)×

(4−

n′

₁)×

(M′

₂)×

(4−

n′

₂)+(M′

₃)×

(4−

n′

₃)+(M′

₄)×

(4−

n′

₄)+ . . . +(M′

_Y)×

(4−

n′

_Y) 

 

Formula (2);

(in the above formula, M′

₁, M′

₂, M′

₃, M′

₄, . . . , M′

_Y represent an atomic ratio of each metallic element having a valence of 4 or less, the atomic ratio being to Ti of titanium dioxide, n′

₁, n′

₂, n′

₃, n′

₄, . . . , n′

_Y represent a valence number of each metallic element having the atomic ratio of M′

₁, M′

₂, M′

₃, M′

₄, . . . , M′

_Y, Y in M′

_Y and n′

_Y represents the number of the metallic element contained in the titanium dioxide and can have a natural number of 1 or more,

with maintaining pH of the aqueous suspension in the range of 2-6 or 8-12, then fractionating the resulting product, and firing the product in an air or in an atmosphere of low oxygen concentration at a temperature of 600-925°

C. to form an electroconductive layer containing tin oxide and phosphorus on the surface of the titanium dioxide.

2. A method according to claim 1, wherein the pH is 8-12.

3. A method according to claim 1, wherein the firing is carried out in the atmosphere of low oxygen concentration.

4. An electroconductive powder obtained by the method of claim 1 wherein the electroconductive powder obtained has an electroconductive layer containing tin oxide and phosphorus, but containing no antimony on the surface of titanium dioxide, and the content of a metallic element having a valence of 4 or less which is contained as an impurity in the electroconductive powder is 0.1 or less as (A) obtained by the following formula (1):

(A)=(M₁)×

(4−

n₁)+(M₂)×

(4−

n₂)+(M₃)×

(4-n₃)+(M₄)×

(4−

n₄)+ . . . +(M_X)×

(4−

n_X) 

 

Formula (1);

(in the above formula, M₁, M₂, M₃, M₄, . . . , M_X represent an atomic ratio of each metallic element having a valence of 4 or less to Sn of the tin oxide in the electroconductive powder, n₁, n₂, n₃, n₄, . . . , n_X represent a valence number of each metallic element having the atomic ratio of M₁, M₂, M₃, M₄, . . . , M_X, X in M_X and n_X represents the number of the metallic element contained in the electroconductive powder and can have a natural number of 1 or more.

5. An electroconductive powder obtained by the method of claim 1 wherein the pH of the aqueous suspension is maintained in the range of 8-12 and the electroconductive powder obtained has an electroconductive layer containing tin oxide and phosphorus, but containing no antimony on the surface of titanium dioxide, and the content of a metallic element having a valence of 4 or less which is contained as an impurity in the electroconductive powder is 0.1 or less as (A) obtained by the following formula (1):

(A)=(M₁)×

(4−

n₁)+(M₂)×

(4−

n₂)+(M₃)×

(4-n₃)+(M₄)×

(4−

n₄)+ . . . +(M_X)×

(4−

n_X) 

 

Formula (1);

(in the above formula, M₁, M₂, M₃, M₄, . . . , M_X represent an atomic ratio of each metallic element having a valence of 4 or less to Sn of the tin oxide in the electroconductive powder, n₁, n₂, n₃, n₄, . . . , n_X represent a valence number of each metallic element having the atomic ratio of M₁, M₂, M₃, M₄, . . . , M_X, X in M_X and n_X represents the number of the metallic element contained in the electroconductive powder and can have a natural number of 1 or more; and

a specific surface area of the electroconductive layer is 70 m²/g or smaller.

6. An electroconductive powder obtained by the method of claim 4 or 5, wherein the amount of the tin oxide forming the electroconductive layer is in the range of 0.015-0.3 g as SnO2 per 1 m² of the surface area of titanium dioxide.

7. An electroconductive powder obtained by the method of claim 4 or 5, wherein the amount of the phosphorus contained in the electroconductive layer with respect to tin oxide is a proportion of 0.10-0.50 in terms of the atomic ratio P/Sn.