Apparatus and method for producing a web of thermoplastic filaments
CA 2133553 C · Owner: Zeldin, Leon M. · Inventors: Francis, John V.; Zeldin, Leon M.; Grubbs, William J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A slot draw attenuator apparatus and method are provided for producing webs of spunbonded thermoplastic filaments having improved cover even at low basis weights. The filaments are introduced to a slot draw attenuator having corona electrodes mounted in an elongate insulator bar and staggered and spaced along one wall of the attenuator slot near the exit end thereof. The corona electrodes are electrically connected to a high voltage source. The opposing wall of the slot is grounded. A corona is created in the attenuator slot so that the filaments are charged as they exit the attenuator. The electrostatic charge induces repelling forces in the filaments so that the filaments spread before …
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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 29, 1993 and granted February 16, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 29, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 29, 2015.
- 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.