摘要 |
Thermoplastic materials which have hot tack and which are incapable of being independently processed by the blown film process due to the tack they show in hot state and especially in the as extruded state are processed to film and sheet by the blown film process by extruding and inflating in a manner known per se an at least two-ply tubular film or sheet of thermoplastic material, the inner ply being formed by a tack-free thermoplastic material and the outer ply superposed thereon being formed by said hot-tacky thermoplastic material; slitting the double-ply tubing for storage and after flattening at least at one edge, and arranging the film web, preferably with winding-up, together with the web of tack-free material in such a manner that one web having hot tack alternates with one tack-free web. The multi-ply film and sheet materials produced by the process are comprised by the invention. |