Procédé pour la production de feuilles coulées en chlorure de polyvinyle et en copolymères de chlorure de vinyle

摘要

Cast films of polyvinyl chloride, or copolymers containing a major proportion thereof, are drawn from the casting support while still containing solvent and after-dried at 150 DEG -300 DEG C., while held only at the sides, to produce a practically solvent-free film. As shown, the sides of the film may be applied to two endless spiked bands or clamp chains c (Fig. 1), by pressure rollers b, and dried in the heated chamber d. Alternatively (Fig. 2), the sides of the film may be applied by deflecting rollers b1 to two driving discs a1, on which the film is held by an endless wire cable or chain c1, and the film subsequently dried in chamber d1. Conventional heating means are used. By leading the spiked bands or clamp chains apart or by canting the discs a1, the film may be stretched transversely during drying. Films so made have a high gloss and are suitable for packaging. Examples describe the preparation of films from solutions in tetrahydrofurane, and in acetone-toluene mixtures.