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PTC Compositions and devices comprising them

  • US 4,534,889 A
  • Filed: 02/22/1983
  • Issued: 08/13/1985
  • Est. Priority Date: 10/15/1976
  • Status: Expired due to Term
First Claim
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1. A process for the preparation of a PTC composition which comprises(1) dispersing conductive particles having a size of at least 18 millimicrons in a polymer;

  • (2) cross-linking the dispersion from step (1) at a first temperature (Tc1) and(3) further cross-linking the cross-linked composition from step (2) at a second temperature (Tc2) which is substantially different from Tc1the composition obtained in step (3) having a gel fraction of at least 0.6;

    exhibiting PTC behavior with an R14 value of at least 2.5 or a R100 value of at least 10 and at least one Ts within the temperature range of -100 to 250°

    C.; and

    having a volume resistivity at temperatures below Ts of 25 to 105 ohm·

    cm.

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