Process for preparing a hydrogel
CA 1181915 A · Owner: Nippon Oil Co. Ltd. · Inventors: Nambu, Masao
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A hydrogel which has a water content of 20 to 92 weight % and which is stable and superior in mechanical properties is obtained by preparing a 3 to 25 weight % aqueous solution of a polyvinyl alcohol having a degree of hydrolysis not less than 95 mol% and a viscosity-average polymerization degree of not less than 1,500, then pouring the aqueous polyvinyl alcohol solution into a desired shape of a vessel or a mold then freeze-molding the aqueous polyvinyl alcohol solution at a temperature lower than -6°C, thereafter dehydrating the molded article without thawing it until the dehydration percentage reaches 5 weight % or more and, if required immersing the, dehydrated product in water.
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
- Granted February 5, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 5, 2002.
- 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.