Process for producing silica particles suitable for use as filler for paper
CA 2265234 A1 · Owner: Okada, Hitoshi · Inventors: Watanabe, Masasuke; Matsuda, Masashi; Kitao, Osamu
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to a process for easily and efficiently producing silica particles having a narrow particle size distribution and a high, porosity from inexpensive starting materials such as sodium silicate. The silica particles of the present invention can be obtained in the form of a slurry, containing them by (1) forming a slurry by mixing first particles difficultly soluble in an alkali and soluble in an acid with an aqueous alkali silicate, solution to form a first slurry containing the first particles (2) , neutralizing the, first slurry with a mineral acid to prepare a second slurry containing second particles wherein silica.is deposited on the first particles and (3) …
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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 11, 1999. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended March 11, 2019.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 11, 2021.
- 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.