Sizing agent and paper sized therewith
CA 2120180 C · Owner: Ishiguro, Osamu · Inventors: Ishiguro, Osamu; Nosaka, Yoshihumi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A sizing agent for paper, which comprises 100 parts by weight of a polyvinyl alcohol (component A) and from 1 to 20 parts by weight of a compound (component B) provided with the following requisites (1) to (4): (1) the backbone chain is a random copolymer of ethylene oxide and propylene oxide, (2) in the backbone chain, the proportion of oxyethylene units is from 20 to 40g by weight, and the proportion of oxypropylene units is from 60 to 80% by weight, (3) of the two terminals one terminal is a hydroxyl group, and the other terminal is a C1-10 alkoxyl group or a hydroxyl group and (4) the, weight average molecular weight is from 600 to 1,200.
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 29, 1994 and granted June 10, 2003. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 29, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 29, 2016.
- 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.