GB883218A - Improvements in or relating to the antistatic treatment of flexible tubular films - Google Patents

Abstract

883,218. Discharging static electricity. BRITISH CELLOPHANE Ltd. May 20, 1960 [June 2, 1959], No. 18859/59. Class 35. [Also in Groups V, XVII and XL (a)] Static electricity on the inner surfaces of thermoplastic tubular film used for making bags (see Group XXII) is eliminated by ionising a captive gas bubble in a film either during the manufacturing process or afterwards. In a preferred embodiment, Fig. 6, the newly made film 10 is fed between a pair of nip rollers 25, 26 round a non-driven roller 27 between a pair of electrodes 31, 32 through nip rollers 28, 30 to a driven drum 29. A bubble of air is introduced between rollers 28, 30 and roller 27, which is ionised by applying an alternating voltage of about 12 kilovolts to electrodes 31, 32 which are 1 / 1 6 inch apart. The electrodes (Fig. 8) consist of thin-walled " Pyrex " (Registered Trade Mark) glass tubing coated on the inner surface with a conductive layer 33 of colloidal graphite. The electrodes 31, 32 are secured by clips 36 to arcuate channel members 34, 35 respectively, the latter member being pivoted to end plates 37, 38 whereby should any foreign matter on the film catch on channel member 35 it would release ball catches 43, 44 and member 35 would fall back to the position indicated in dotted lines in Fig. 8. Static electricity on the outer surfaces of the film is dissipated by conventional static eliminators 49, 50. In an alternative embodiment the electrodes consisted of brass tubing wrapped in a film of polyester and connected to a 50 c/s. 9-kilovolt source. Any known means of ionisation may be used.