Organic PTC thermistor and making method

• US 20030091829A1
• Filed: 11/15/2002
• Published: 05/15/2003
• Est. Priority Date: 11/15/2001
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Handa, Tokuhiko, Yoshinari, Yukie
• Granted Patent: US 6,778,062 B2
• Time in Patent Office: Days
• US Class Current: 428/413
• CPC Class Codes: C08K 3/08 Metals
• CPC Class Codes: G01K 7/22 the element being a non-linear resistance, e.g. thermistor G01K7/26 takes precedence
• CPC Class Codes: G01K 7/226 using microstructures, e.g. silicon spreading resistance
• CPC Class Codes: H01C 17/06513 characterised by the resistive component
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: Y10T 428/249921 Web or sheet containing structurally defined element or component
• CPC Class Codes: Y10T 428/31 Surface property or characteristic of web, sheet or block
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31522 Next to metal

Abstract

In an organic PTC thermistor comprising an organic polymer matrix and conductive metal particles dispersed therein, the conductive metal particles are pretreated with an organic material which is different from the organic polymer matrix, does not covalently bond with the conductive metal particles, and is not compatible at a molecular level with the organic polymer matrix so that an organic material layer covers surfaces of conductive metal particles whereby the stability of thermistor performance is improved.

Claims

1. An organic positive temperature coefficient thermistor comprising an organic polymer matrix and conductive metal particles dispersed therein, wherein

a layer made of an organic material which is different from the organic polymer matrix, does not covalently bond with the conductive metal particles, and is not compatible at a molecular level with the organic polymer matrix is disposed in close proximity to surfaces of the conductive metal particles.

2. The organic positive temperature coefficient thermistor of claim 1, wherein said organic material is not reactive with the organic polymer matrix.

3. The organic positive temperature coefficient thermistor of claim 1, wherein said conductive metal particles comprise nickel or copper.

4. The organic positive temperature coefficient thermistor of claim 1, wherein said organic polymer matrix comprises a thermoplastic polymer.

5. The organic positive temperature coefficient thermistor of claim 1, further comprising a low-molecular weight organic compound.

6. The organic positive temperature coefficient thermistor of claim 1, wherein said conductive metal particles have spiky protuberances.

7. The organic positive temperature coefficient thermistor of claim 1, wherein said organic material is biodegradable.

8. A method for preparing an organic positive temperature coefficient thermistor, comprising the steps of:

pretreating conductive metal particles with an organic material so that the organic material covers surfaces of the conductive metal particles, and

mixing the treated conductive metal particles with an organic polymer matrix for dispersion.

9. The method of claim 8, wherein said organic material is different from the organic polymer matrix, does not covalently bond with the conductive metal particles, and is not compatible at a molecular level with the organic polymer matrix.

10. The method of claim 8, wherein said organic material is not reactive with the organic polymer matrix.

11. The method of claim 8, wherein said conductive metal particles comprise nickel or copper.

12. The method of claim 8, wherein said organic polymer matrix comprises a thermoplastic polymer.

13. The method of claim 8, wherein said organic polymer matrix further comprises a low-molecular weight organic compound.

14. The method of claim 8, wherein said conductive metal particles have spiky protuberances.

15. The method of claim 8, wherein said organic material is biodegradable.