Process and apparatus for determining the bowing value of an oriented polymer film, and polymer film orientation process including the determination of the bowing value

摘要

The invention relates to a process and apparatus for determining the bowing value of an oriented polymer film in the course, and without interruption, of a process of at least transversely orienting said polymer film on a plant for at least transversely orienting said film, said process comprising the steps of(a) marking, the latest before the transverse orientation step, at least one surface of the polymer film with a pattern of bowing marks (11) allowing to recognize a geometric pattern;(b) orienting said polymer film at least in the transverse direction;(c) passing said at least one surface of the oriented polymer film along a determination means capable of recognizing a geometric pattern of bowing marks (12) on said at least one surface;(d) making said determination means recognize and receive said geometric pattern of bowing marks (12);(e) continuing and terminating said transverse orientation step of the polymer film; and converting said geometric pattern of bowing marks recognized and received by the determination means into geometric bowing mark pattern data.