Corona discharge treatment for air-cushion double-layer film - having projections and cover which passes through corona and coating head

摘要

Air cushion type double-layer films are subjected to corona treatment, using discharge electrode(s) and counter electrode(s). The electrical resistance of the film greater at the points between its projection than at the projections themselves. A heated sintered metal drum is internally evacuated to produce projections on the one film. A heated silicone rubber conveyor belt has perforations to fit the film projections. Polyethylene film passes on to the roller and is drawn out into the projections. A top cover film then meets it before it is cooled. The corona discharge is provided by a h.t. electrode at 25 Hz 12kV and a counter electrode. The film combination then passes to a coating head. The pretreatment on the projections side provides satisfactory bonding for the adhesive used.