Process for the twin-web hot embossing of thermoplastic film

A process for embossing thermoplastic polyolefin film which comprises.

• (a) passing a length of said film consisting of two superimposed webs in direct face-to-face contact into a heating zone to heat said webs to a temperature above the vicat softening point but below the melting point of said film each of said webs being free from release agent coated on the interface surfaces of said superimposed webs;
• (b) passing the heated superimposed webs between a pair of embossing rolls at least one of which has an engraved metallic surface cooled to a temperature sufficient to cool said webs to below the vicat softening point;
• (c) passing said webs into the nip between a pair of counter rotating driven rolls, each having a high friction surface, separating said webs downstream of said nip by each of said webs maintaining contact with the surface of its respective driven roll, each having a high friction surface, separating said webs downstream of said nip by each of said webs maintaining contact with the surface of its respective driven roll downstream of said nip, passing each of said webs around a sufficient portion of the circumference of its respective driven roll and under sufficient tension to prevent slippage, releasing each of said webs from its respective driven roll by continuing passage over a co-operating roll, then;
• (d) drawing each of said webs to a separate wind-up station.