Composite web decurling apparatus and method

An apparatus for treating a moving web of laminated composite material of the type having a relatively thin film layer adhered to a relatively thick paper layer for eliminating the tendency of the web to curl toward the film layer side thereof subsequent to being stored on a spool with the film layer of the web positioned inwardly of the paper layer of the web, the film layer and paper layer each having an exposed surface and an attached surface said attached surfaces of said layers being adhered together, said paper layer having an outwardly positioned thickness portion which terminates at said exposed surface thereof, an inwardly positioned thickness portion which terminates at said attached surface thereof and an intermediately positioned thickness portion positioned between said outwardly positioned thickness portion and said inwardly positioned thickness portion, said outwardly positioned thickness portion being relatively stretched, said inwardly positioned thickness portion being relatively shrunk, said intermediately positioned thickness portion being relatively unstretched and unshrunk, said film layer being relatively shrunk through storage of the composite web on the spool, comprising:

• (a) composite web supply means for supplying the moving web of composite material to be treated;
• (b) composite web film heating means for heating said film layer portion of said composite web to a temperature sufficient to place said film layer in a readily deformable, substantially nonelastic state for a relatively short period whereby relative stretching deformation occurring in said film layer caused by stretching forces applied thereto during said nonelastic state thereof is not accompanied by shrinking of said film layer subsequent to removal of said stretching forces, the amount of film layer stretching occurring during said nonelastic state being limited to the amount of relative stretching occurring in said relatively inwardly positioned portion of said paper layer of said web;
• (c) composite web paper heating means for heating said exposed surface of said paper layer for causing a relative drying in said relatively outwardly positioned portion of said paper layer for causing relative shrinking of said outwardly positioned portion of said paper layer and for causing relative hydrating of said inwardly positioned portion of said paper layer for causing relative stretching of said inwardly positioned portion;
• the stretching occurring in said inwardly positioned portion of said paper layer and in said film layer and the shrinking occurring in said outwardly positioned portion of said paper layer being of an amount whereby oppositely positioned portions of said film layer and said paper layer of said web are of substantially equal length in an unstressed state subsequent to treatment by said apparatus whereby the tendency of the composite web to curl toward said film layer side is eliminated.