Thermoplastic film and method of welding same
CA 2104864 C · Owner: Desmarais & Frere Ltd. · Inventors: Desmarais, Claude; Desmarais, Richard
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
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, and EVA copolymer and polypropylene, and an EVA copolymer and polyethylene and polypropylene with the proviso that the concentra-, tion 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.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 20, 1992 and granted March 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 20, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 20, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.