Method for applying closure strips to plastic film

Abstract

A method of and apparatus for manufacturing stock material from which bags or other containers may be formed is disclosed. A folded plastic film is fed from a stock roll onto a plurality of carrier rollers which support the film in a horizontal position. Simultaneously, a separate closure strip is fed from a second stock roll through a guide block which aligns the strip with a sealing station, the two halves of the closure strip being pressed together to maintain proper alignment. The upper ply of the folded plastic film is fed into the heat sealing apparatus at the sealing station, the edge of the upper ply being aligned with one edge of the closure, and the film and the closure strip are fed continuously through the sealing station where they are welded together. The lower ply of the film web is folded downwardly so that it bypasses the sealing station. After the film and closure strip pass out of the sealing station, the lower ply is folded upwardly so that it coincides with the free edge of the closure strip. The film and closure strip are then fed through guide rollers and a second guide block which aligns the free edge of the closure strip and the edge of the lower ply of the film with a second sealing station, where these two edges are welded together. Thereafter, the completed stock material is fed to a take-up reel for storage or to a suitable bag forming machine.