Method and apparatus for preparing thermoplastic foam
CA 2006361 A1 · Owner: Korb, Jean G. · Inventors: Harfmann, Walter R.; Korb, Jean G.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Thermoplastic foam is prepared by a continuous process comprising melt mixing thermoplastic resin; pressurizing the resin melt; introducing blowing agent; cooling and depressurizing the resultant gel; and either foaming and forming the gel to form a solid foam or forming the gel to form a foamable composition. The process temperature is maintained substantially independently of the flow rate of the resin melt and gel at below that at which substantial depredation of the resin gel occurs. The process has particular application to rubber-modified polystyrene or rubbermodified polyethylene resin foam compositions containing a fire retardant. 33,584-F
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 December 21, 1989. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended December 21, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 21, 2011.
- 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.