Method of making electret articles and filters with increased oily mist resistance
CA 2304284 A1 · Owner: Minnesota Mining And Manufacturing Company · Inventors: Mei, Betty Z.; Jones, Marvin E.; Rousseau, Alan D.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An electret article can be made by quenching a molten blend containing a polymer and a performance-enhancing additive. The resulting low crystallinity material can be annealed and charged to produce a material for making electret filters having superior oily mist loading performance properties.
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 February 2, 1998. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended February 2, 2018.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 2, 2020.
- 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.