| 摘要 |
<p>An electrical heating element material of a sheet form is provided, which is comprised of a web of a synthetic resin having a plurality of metal conductor wires arranged therein in parallel to one another along the longitudinal direction of the web. The web is folded in succession at predetermined intervals along folding lines inclined at a small acute angle to the transverse direction of the web to form a substantially two-layer parallelogrammatic sheet. Considering the small angle, the sheet is, for practical purposes, rectangular. The electrical heating element material is prepared by supplying a plurality of metal conductor wires arranged in parallel to one another into a cross-head type extrusion die, separately supplying a thermoplastic resin into said die, co-extruding the resin together with the wires to form a web, folding the web in succession at predetermined intervals along folding lines inclined at an acute angle to the transverse direction of the web to form the two-layer rectangular sheet, and then, optionally, bonding together the two layers. The electrical heating element material may be used as a heat-shrinkable cover, which is comprised of a heat-shrinkable synthetic resin member and the electrical heating element material combined with the heat-shrinkable resin member substantially over the entire region thereof.</p> |
