Organic PTC thermistor

• US 6,607,679 B2
• Filed: 01/12/2001
• Issued: 08/19/2003
• Est. Priority Date: 01/12/2001
• Status: Expired due to Fees

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Handa, Tokuhiko, Yoshinari, Yukie
• Primary Examiner(s): Gupta, Yogendra N.
• Assistant Examiner(s): HAMLIN, DERRICK G
• Application Number:
  US09/758,291
• Publication Number:
  US 20020093007A1
• Time in Patent Office: 949 Days
• Field of Search: 252/500, 252/511, 252/512, 252/513, 252/518.1, 219/541, 219/546, 219/547, 219/553, 264/104, 264/150, 264/234, 264/347, 338/22.R
• US Class Current: 252/513
• CPC Class Codes: H01C 17/06586 composed of organic material
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: H01M 10/4235 Safety or regulating additives or arrangements in electrodes, separators or electrolyte H01M10/4242 takes precedence
• CPC Class Codes: H01M 2200/106 PTC
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In an organic PTC thermistor comprising a matrix of at least two high-molecular weight compounds, a low-molecular weight organic compound, and conductive particles having spiky protuberances, a thermoplastic elastomer is contained in the matrix whereby the thermistor is improved in reliability and performance stability.

Claims

1. An organic positive temperature coefficient thermistor comprising

a matrix including at least two polymers, where at least one of the at least two polymers is a thermoplastic elastomer;

a low-molecular weight organic compound selected from the group consisting a wax, a fat and an oil; and

conductive particles having spiky protuberances.

2. The organic positive temperature coefficient thermistor of claim 1, wherein said matrix contains 2 to 60% by weight of the thermoplastic elastomer.

3. The organic positive temperature coefficient thermistor of claim 1, wherein said low-molecular weight organic compound has a melting point in a range of from 40°

C. to 200°

C.

4. The organic positive temperature coefficient thermistor of claim 1, wherein said conductive particles having spiky protuberances are interconnected in chain-like network.

5. The organic positive temperature coefficient thermistor of claim 1, wherein said low-molecular weight organic compound is segregated in said matrix.

6. The organic positive temperature coefficient thermistor of claim 1, which constitutes a protective circuit device for a secondary battery.

7. The organic positive temperature coefficient thermistor of claim 1, wherein each of said at least two polymers has a melting point higher than a melting point of the low-molecular weight organic compound.

8. The organic positive temperature coefficient thermistor of claim 1, wherein said at least two polymers comprise a thermoplastic polymer and a thermosetting polymer.

9. The organic positive temperature coefficient thermistor of claim 1, wherein said thermoplastic elastomer has a melting point at least 10°

C. higher than a melting point of the low-molecular weight organic compound.

10. The organic positive temperature coefficient thermistor of claim 1, wherein said thermoplastic elastomer has a melting point in a range of from 100°

C. to 180°

C.

11. The organic positive temperature coefficient thermistor of claim 1, wherein said matrix contains 5% to 40% by weight of the thermoplastic elastomer.

12. The organic positive temperature coefficient thermistor of claim 1, wherein said low-molecular weight organic compound has a melting point in a range of from 40°

C. to 100°

C.

13. The organic positive temperature coefficient thermistor of claim 1, wherein said low-molecular weight organic compound comprises a petroleum wax.

14. The organic positive temperature coefficient thermistor of claim 1, wherein each of said conductive particles comprises from 10 to 500 spiky protuberances each having a height in a range of from ⅓

to {fraction (1/50)} of a conductive particle diameter.

15. A method of making a positive temperature coefficient thermistor, the method comprising

mixing at least two polymers, a low-molecular weight organic compound, and conductive particles; and

producing the thermistor of claim 1.