Isocyanate modified cellulose products and method for their manufacture
CA 2096534 C · Owner: Weyerhaeuser Company · Inventors: Lincoln, James F.L.; Park, David W.; Hunter, Frank R.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method is disclosed for producing a polyurea-cellulose composite material from substantially delignified cellulosic material and an isocyanate resin. The isocyanate resin comprises a polyisocyanate preferably PMDI, and a miscible organic solvent preferably one such as propylene carbonate having a high boiling point and low flammability and toxicity. The composite surprisingly exhibits values of physical parameters that are at least as good as and sometimes far superior to, corresponding parameters of similar composites made using neat (undiluted) polyisocyanate. Single- and multiple-ply composites can be made employing, only a single curing step.
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 October 17, 1991 and granted March 23, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 17, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 17, 2013.
- 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.