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US3760495A Expired / Lapsed US ⏱️ 0.0 years remaining

Process for making conductive polymers

Assignee: Texas Instruments Inc
•
Filing: 1971-12-22
•
Granted: 1973-09-25
•
Expires: 1991-12-22
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Abstract

Abstract Conductive polymer having a steeply-sloped positive temperature coefficient (PTC) of resistance with a sharply defined anomaly temperature is provided by selecting a polymer having crystalline structure at room temperature, a glass transition of approximately 13*F. or lower and a narrow molecular weight distribution as measured by a flow ratio of less than 9 or a melting point range of 30* C. or less. The polymer is filled with conductive particles and may include additional additives such as stabilizing agents and flame retardants. The ingredients are mixed, subjected to shearing forces and then formed into the desired configuration. The maximum permissible processing temperature is identified for the specific polymers employed.

Inventors

  • 👤 J Meyer

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-25 08:27
CPC Classifications
H; H01; H01B; H01B1/00; H01B1/20; H01B1/22; H01C; H01C7/00; H01C7/02; H01C7/027; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 25 words
The method according to claim 1 in which the temperature of the mix is maintained below the oxygen pick up temperature for the polymer employed.
Claim 2
Dependent Claim 47 words
The method according to claim 1 further including providing a sharp transition between the resistance level at a temperature below the anomaly and the steeply sloped portion of the resistance temperature curve at temperatures above the anomaly by choosing a polymer having a narrow molecular weight distribution.
Claim 3
Dependent Claim 18 words
The method according to claim 3 in which the polymer has a flow ratio of less than 9.
Claim 4
Dependent Claim 19 words
The method according to claim 3 in which the polymer has a melting temperature range within approximately 30* Centigrade.
Claim 5
Dependent Claim 21 words
The method according to claim 1 in which the conductive filler is carbon black from 14 to 20 percent by weight.
Claim 6
Dependent Claim 37 words
The method according to claim 1 in which the polymer is selected from the group consisting of high density polyethylene, low density polyethylene, polypropylene, polyethylene oxide, trans 4 polybutadiene and a mixture of polyethylene and polyethyl acrylate.
Claim 7
Dependent Claim 23 words
The method according to claim 1 in which the conductive particles are selected from the group consisting of carbon, tin, silver and gold.
Claim 8
Dependent Claim 33 words
The method according to claim 7 in which the approximate maximum processing temperatures for the group of polymers are 350* F., 320* F., 420* F., 190* F., 300* F. and 350* F. respectively.

References Cited (Backward Citations)

US3164796A Cited
US3243753A Cited
US3414704A Cited
US3414705A Cited
US3518407A Cited
US3571777A Cited
US3619560A Cited
US3617695A Cited
US3689736A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-09-24 1977-03-26 1977-09-25 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-09-24 1981-03-26 1981-09-25 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-09-24 1985-03-26 1985-09-25 $7700.00 Window Closed / Lapsed

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