Ground limestone as a filler in paper
CA 1072258 A · Owner: P.H. Glatfelter Company · Inventors: Bauman, Harry D.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Combinations of fine particle size precipitated CaCO3 and coarser natural ground limestones up to about, 35% ground limestone, have the same opacifying power in paper as does 100% precipitated CaCO3, provided the ground limestone has the proper particle size distribution.
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 26, 1980. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 26, 1997.
- 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.