Corona discharge pretreatment device for valved plastics sacks - for printing, uses electrode which is lifted from support roller to allow bag to pass

摘要

Device for corona discharge treatment of valved plastics bags preparatory to printing upon them, features a discharge electrode which is lifted by a cam control from a carrier roller as the valve and the bottom of the bag moves past it. This lifting distance is greater than that min. distance necessary for the corona discharge treament. Used for improving adhesion of printing ink to bag. Normally the gap between electrode and carrier roller is 0.8-1.5mm which is not enough to allow a bag with valve and bottom to pass, so that such bags could not be corona-treated in prior mfr. This disadvantage is removed, in simple fashio, by the device described.