Isocyanate modified cellulose products and method for their manufacture
CA 2089489 C · Owner: Richwood Industries, Inc. · Inventors: Hunter, Frank R.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention is a method of making a cellulose based polymeric material arid the products of the invention. A cellulosic substrate is impregnated with an essentially uncatalyzed polyfunctional isocyanate and pressed at elevated temperature and pressure. The substrate may be a chemical or thermomechanical pulp or paper while the isocyanate is preferably diphenylmethane diisocyanate or its oligomers. Pressing conditions are preferably in the range of about 150°-245 °C at pressures in the range of about 2700-8300 kPa for times less than 2 minutes. Moisture content of the cellulosic substrate is not highly critical and may be as high as 7 % without adverse effects. The product is …
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 August 13, 1990 and granted February 13, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 13, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 13, 2012.
- 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.