초록 ▼

The invention provides a method of forming single or multi-wall plastic tubing and more particularly, in forming single or multi-wall plastic bags wherein the seal area is strengthened by utilizing a plurality of extruded layers of adhesive material in the seal area. This would particularly be the c

The invention provides a method of forming single or multi-wall plastic tubing and more particularly, in forming single or multi-wall plastic bags wherein the seal area is strengthened by utilizing a plurality of extruded layers of adhesive material in the seal area. This would particularly be the case for valved bags.

대표청구항 ▼

A method of forming a plastic bag having a reinforced seam area from double wall tubing comprising the steps of feeding at least first and second layers of a thermoplastic sheet material into proximity to each other, said first and second layers having their side edges generally in alignment, extrud

A method of forming a plastic bag having a reinforced seam area from double wall tubing comprising the steps of feeding at least first and second layers of a thermoplastic sheet material into proximity to each other, said first and second layers having their side edges generally in alignment, extruding a layer of reinforcing material on at least one facing surface of at least one layer of sheet material at each side edge thereof in a continuous in-line operation, said layer of reinforcing material being extruded in the form of a band of a predetermined width and thickness which is sufficient to form and function as a reinforcing layer to reinforce the adjoined edges juxtaposing and adhering said side edges together such that said first and second layers of sheet material form a double wall structure having said first and second layers spaced apart at their edges by said layer of reinforcing material and where the layer of reinforcing material still retains sufficient width and thickness after adhering said side edges together to function as a reinforcing layer in the bag, folding one of said pair of adhered edges over to form a double wall tube with said adhered edges overlapping each other, extruding a further layer of reinforcing material on a facing surface of at least one of said overlapped edges, and securing said overlapped edges together along at least a portion of the length of said secured edges overlapped to thereby form a tubing structure having four layers of overlapped sheet material with a reinforcing layer intermediate each adjacent sheet material.