Attaching discrete lengths of zipper at spaced intervals across a web of bag making film has an endless belt supported between a pair of pulleys for moving zipper segments into position on the web. The zipper segments are cut from a zipper supply and fed into a nip between the endless belt and the web top surface.

After a zipper segment is deposited into position on the web, the endless belt is raised. A vertically movable sealing bar below the web is raised into position to heat the web to seal the zipper to the web after which the sealing bar is lowered. The web then advances and the process is repeated.

Disclosed for producing a reclosable plastic bag having a zipper that extends transverse to the longitudinal or running direction of the web of the film from which the bag is formed. In accordance with the disclosed method, a zipper segment having interlocked profiles is fed transversely across a web of bag making film nd one of the profiles is attached to the web. The length of the segment is equal to approximately half the width of the desired bag. At a bag making machine the web is formed into a tube by sealing the edges of the film together with seal bars after which the other profile of the zipper is attached to an inner surface of the tube by seal bar. The construction of bag is completed by forming a cross seal by seal bar which also serves to sever the completed bag from the tube.

For one thing, such zippers utilize less plastic and hence tend to be cheaper than zipper with flanges. In addition, because of their smaller size, greater lengths of flangeless or limited-flange zipper can be wound on comparably sized rolls as compared with flanged zipper which enables longer production runs.

The zipper profiles may be flanged, flangeless or anything in between. In accordance with the present invention, an apparatus for attaching discrete lengths of zipper at spaced intervals across a film has an endless belt supported between a pair of pulleys for moving a zipper segment onto a web of bag making film moving along a path off a supply roll. The zipper consists of profiles with interlocked engagement elements and is fed with one profile atop the other.

The zipper segments are cut from a zipper supply and fed into a nip between the endless belt and the web top surface. After a zipper segment is deposited into position on the web, the pulleys are raised to disengage the zipper segment from being driven further by the endless belt. A sealing bar below the web is then raised into position to heat the bottom surface of the web to seal the bottom profile of the zipper to the web top surface after which the sealing bar is lowered. The web then advances and the process is repeated. The resultant bag making film with attached zipper may then be fed directly into a bag making machine or spooled for later use.

The zipper sealer consists of a seal bar that is vertically movable by a two stage cylinder between a lower position and a raised position. When in the lower position, the seal bar is out of contact with the bottom surface of a web on a support surface of the applicator and spaced sufficiently far beneath the web so that it does not affect the web. In the raised position, the sealing bar contacts the web bottom surface and seals the bottom of the lower profile of zipper to the top surface of the film web. To this end, the bottoms of the zipper profiles may be coated with a sealant layer, such as EVA, to facilitate sealing the zipper to the bag making film. A thermocouple and heater element are provided in the seal bar in the conventional manner to control the temperature for optimum sealing.

Thus, the desired objectives of the present invention are effectively attained. It should be understood that modifications of the preferred embodiment will be readily apparent to those skilled in the art. For example, rather than spooling the web of bag making film with attached zipper, the zipper applicator may be placed upstream of the bag making equipment so that the film web with applied zipper can be fed directly into the bag making equipment. Also, rather than intermittently stopping the film for each zipper length application, the zipper applicator may be fixed to a shuttle that moves with the film during zipper application and then moves back to the zipper receiving position.