GB827429A - Apparatus for the surface treatment of plastic material films to make the printing indelible - Google Patents

Abstract

Apparatus for continuously treating the surfaces of continuous webs of film of organic thermoplastic high polymers comprises an assembly of rotatable earthed rollers arranged in a row, having their axes of rotation parallel with one another and lying in a common plane, and at least one stationary flat plate electrode located in a plane parallel to the plane of the roller axes a short distance from the rollers and electrically connected to a high-frequency high-voltage electricity supply, and means for causing the continuous web of film to travel in a <PICT:0827429/IV (a)/1> sinuous path over and under in contact with all the rollers past the stationary electrode or electrodes. The periphery of each roller is preferably provided with a sheath of dielectric material. As shown, a web of film 16 is passed from a feed roller 17 in a generally sinuous path over two rows in series of freely rotatable earthed metal rollers 12, each row being located between a pair of fixed plate electrodes 11a, 11b located in a housing 1, to a wind-up roller 18. The electrodes 11a, 11b are electrically connected with the secondary circuit of a step-up transformer providing a supply of high-frequency high-voltage electricity. The upper plates 11a are mounted on covers 14, symmetrically hinged at 15; thus the plates 11a may be raised in order to obtain access to the rollers 12 to facilitate initial threading up of the film around the rollers and for cleaning. The surfaces of the fixed plate electrodes facing the rollers may be provided with recesses conforming with the shape of the rollers. The treatment improves the adhesion of printing inks to the films.