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Abstract

A method of forming a series of tray containers from plastic sheet film including intermittently continuously advancing a sheet of film, forming pockets in the film by heating and pressure differential across the film, laterally delivering closure strips between the pockets with the closure strips doubled, and having upper and lower layers with rib and groove fastener profiles therebetween, attaching the lower layer of the fastener to the web at the upper and lower edges of the fastener, laying an upper layer of film over the lower layer and attaching it to the lower layer around the edges of the pockets and attaching the upper layer of film to the top edge of the doubled fastener strip with the upper layer of the fastener strip having a tear perforation sealed by a sealing strip below the rib and groove elements.

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First Claim