| 摘要 |
Positive temperature coefficient polymer (PTC) materials of high loading with uniformly distributed electrically conductive material are manufactured by first producing an intimate mixture (pre-mix or master batch) of a crystalline polymer (e.g. high-density polyethylene) with an electrically conductive filler (e.g. carbon black) in proportions that is less rich in the filler than the final PTC product. The intimate mixture, pre-mix or master batch, is utilized in a subsequent step in a molten liquid form for admixing with more filler material in quantities to produce the desired loading of the filler in the polymer matrix. The resulting admixture is extruded, shaped and formed by conventional equipment to provide a positive temperature coefficient polymer composition that, when equipped with electrodes, is suitable for forming positive temperature coefficient circuit protecting devices. Positive temperature coefficient polymer composition having electrically conductive filler, usually carbon black in ratios as high as 55 to 60 percent by weight can be obtained by the process. |
