Self-regulating laminar heating device and method of forming same

• US 5,344,591 A
• Filed: 04/01/1993
• Issued: 09/06/1994
• Est. Priority Date: 11/08/1990
• Status: Expired due to Fees

• Current Assignee: Jack H. Smuckler
• Original Assignee: Jack H. Smuckler
• Inventors: Smuckler, Jack H.
• Primary Examiner(s): Lieberman, Paul
• Assistant Examiner(s): KOPEC, MARK T
• Application Number:
  US08/041,814
• Time in Patent Office: 523 Days
• Field of Search: 252/502, 252/510, 252/511, 252/512, 252/518, 524/495, 524/496, 219/505
• US Class Current: 252/511
• CPC Class Codes: B60R 1/0602 comprising means for cleaning or deicing
• CPC Class Codes: B60S 1/026 using electrical means
• CPC Class Codes: H05B 3/146 Conductive polymers, e.g. polyethylene, thermoplastics
• CPC Class Codes: H05B 3/845 specially adapted for reflecting surfaces, e.g. bathroom - or rearview mirrors

Abstract

A positive temperature coefficient composition comprising a dispersion of conductive particles in a solvated or solvatable crystalline organic polymer is disclosed. Temperature self-regulating devices incorporating the composition and related method of manufacture are described.

Claims

1. A PTC composition comprising:

a. a continuous, single phase solution comprising (1) greater than 10% by weight of a crystalline polyurethane or polychloroprene polymer having a degree of crystallinity of at least 5%, and (ii) an organic solvent or solvent blend, wherein said polymer remains soluble in said solvent or solvent blend at a temperature in the range of from about 60°

F. to about 80°

F.; and

b. electrically conductive particulate material dispersed throughout said single phase solution in an amount of from about 20% to about 60% by weight,

wherein said composition when dried has a switching temperature which approximates the crystalline melt temperature of the polymer.

2. The composition of claim 1 wherein the degree of crystallinity of the crystalline polymer is determined by x-ray diffraction.

3. The composition of claim 1 wherein said electrically conductive particulate material comprises carbon black.

4. The composition of claim 1 wherein said electrically conductive particulate material is a blend of carbon black and graphite.

5. The composition of claim 3 wherein said electrically conductive particulate material is low structure carbon black having a DBP absorption less than 100 cc/100 g of carbon black.