| abstract |
A method of welding at least two layers of a thermoplastic film which comprises a copolymer or copolymer-polymer mixture selected from the group consisting of ethylenevinylacetate (EVA) copolymer, an EVA copolymer and polyethylene, an EVA copolymer and polypropylene, and an EVA copolymer and polyethylene and polypropylene, with the proviso that the concentration of vinylacetate in said film is from about 12 to about 28% by weight, said method comprising the steps of: pressing said at least two layers of said thermoplastic film; applying a high frequency current to said pressed layers in order to weld said layers together; and recovering said welded layers. |