Patent ID: 9502162
Filing Date: 2016-11-22
CPC Classification: H01B,H01C,H02H

Claim Text:
1. A PTC circuit protection device comprising: a PTC polymer material; and two electrodes attached to said PTC polymer material; wherein said PTC polymer material includes a polymer matrix and a particulate conductive filler dispersed in said polymer matrix, said conductive filler including conductive non-carbonaceous particles and conductive carbon particles, said non-carbonaceous particles having a resistivity greater than that of said carbon particles; wherein said polymer matrix is made from a polymer composition that contains at least a primary polymer unit and a reinforcing polyolefin, said primary polymer unit containing a base polyolefin and optionally a grafted polyolefin, said reinforcing polyolefin having a weight average molecular weight greater than that of said base polyolefin, said primary polymer unit and said reinforcing polyolefin being co-melted together and then solidified to form said polymer matrix; wherein said base polyolefin has a melt flow rate ranging from 10 g/10 min to 100 g/10 min measured according to ASTM D-1238 under a temperature of 230° C. and a load of 12.6 Kg; wherein said reinforcing polyolefin has a melt flow rate ranging from 0.01 g/10 min to 1 g/10 min measured according to ASTM D-1238 under a temperature of 230° C. and a load of 12.6 Kg; wherein said conductive carbon particles have an average particle size ranging from 40 to 100 nm, a DBP oil-absorption ranging from 60 to 120 cc/100 g, and a volatile content ranging from 0.2 to 2.0 wt %; wherein said primary polymer unit is in an amount ranging from 58 to 92 wt % and said reinforcing polyolefin is in an amount ranging from 8 to 42 wt % based on the total weight of said polymer composition; wherein said polymer matrix is in an amount ranging from 10 to 14 wt % and said conductive filler is in an amount ranging from 86 to 90 wt % based on the total weight of said PTC polymer material; and wherein said conductive carbon particles are in an amount ranging from 1 to 14 wt % based on the total weight of said PTC polymer material.