Method of making polyethylene shipping sack with flexographically applied barrier coating

Claim 1

A process for making bags, sacks and like containers having an internal barrier coating comprising: (a) treating one surface of a length of polyethylene film adapted to be folded and heat sealed to make a bag, so as to make said surface receptive to printing inks; (b) to the treated surface except portions thereof which are to be heat sealed, flexographically applying a layer of a lacquer comprising a solution of a nylon resin in at least one alcohol selected from the C1-C5 aliphatic alcohols and mixtures of at least one of said alcohols with up to 15% by weight of water; (c) drying the applied lacquer and folding opposite sides of the length of now coated polyethylene film inwardly of the nylon coating until the edge portions overlap one another; (d) heat sealing the overlapping portions together along the length of the overlapping region; and (e) heat sealing one of the two open ends transversely of the folded length of film, the other end being left open but being heat sealable.