Method of improving the adhesive properties of polyolefin film by passing a diffuse electrical discharge over the film's surface

摘要

1,042,049. Printing processes. IMPERIAL CHEMICAL INDUSTRIES Ltd. (Canadian Industries Ltd.). Nov. 4, 1964 [Nov. 12, 1963], No. 44619/63. Heading B6C. A plastics, e.g. polythene, web 1 in single thickness or flattened tubular film form is subjected to a diffuse direct current corona discharge prior to printing such discharge being effected between spaced electrodes 7 and 9, the latter being at the lower potential and following the former in the direction of movement of the web. The web 1 passes over an earthed conductive roller 2 covered with an insulant 3- which may be a polyethylene terephthalate film -whilst being subjected to the discharge and is guided by rollers 5, 6. In a modified treatment apparatus the web passes nearly all round the roller 2, the electrodes 7 and 9 are diametrically opposed and an additional electrode, which is earthed, is placed before the electrode 7 in the direction of web travel. A further earthed electrode may be placed adjacent the insulated surface of the roller at a position beyond the line at which the treated web leaves the roller. A radio-active source of ionization may be employed to ionize the atmosphere between the electrodes.