Polymer film treatment with organic impregnant

Abstract

Acrylonitrile polymer film is treated with non-volatile water-miscible glycol plasticizer to improve toughness and other film properties. In a unique, continuous, steady state process polyacrylonitrile aquagel strip is treated with plasticizer additive in concentrated aqueous solution. Aquagel strip is passed at substantially constant rate through a solution treatment bath. The aquagel strip, which may contain at least about 40 weight % water uniformly dispersed in the polyacrylonitrile, is contacted with the aqueous solution during a predetermined residence time in the bath. After passing the treated aquagel strip from the bath, excess aqueous additive solution is removed. The plasticizer additive can be metered to the aqueous solution at concentration greater than the aqueous additive solution of the bath at a rate substantially proportionate to desired steady state uptake of additive for the aquagel strip. By impregnating the film with a low molecular weight glycol, such as triethylene glycol, in-line plasticizer addition is achieved. Novel glycol-plasticized acrylonitrile polymers and packaging films are made.

Dependencies are inferred from the claim text.