| 摘要 |
PURPOSE:To manufacture excellent heat-shrinkable tubing, the inner and outer layers of which are respectively uniform and the shrinking characteristics of which is uniform, without necessity of the manufacture of adhesive layer in separate process and influence of the thickness of outer layer material by a method wherein the outer layer material made of polyolefin-based resin, only which contains crosslinking agent, and the inner layer material, which is adherent to the outer layer material, are co-extruded and, after that, only the outer layer material is crosslinked. CONSTITUTION:Outer layer material made of polyolefin-based resin containing crosslinking agent and inner layer material made of resin adherent to the outer layer material are co-extruded in tubular form. Said tubing is crosslinked by heating and, in succession, continuously enlarged radially (expanded) and finally cooled so as to manufacture heat-shrinkable tubing. By the above-mentioned manufacture, heat- shrinkable tubing, the outer layer material of which is crosslinked and the inside inner layer material of which functions as adhesive, is easily obtained. As the polyolefin-based resin used, there is no special limit and polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer or the like is exampled. Further, as the adherent resin used for inner layer material, there is no special limit and the use of hot melt-based resin, for example, is favorable. |
