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Expired Canadian patentCanada

Inhibition of water-treeing in polyolefin electrical insulation

CA 1183297 A · Owner: Nippon Unicar Company Ltd. · Inventors: Igarashi, Kenji; Kawasaki, Youichi; Taniguchi, Seiho

CIPO record

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Abstract From the Canadian patent

A polyolefin composition for electrical insulation which comprises polyolefin or crosslinked polyolefin and a small quantity of high-molecular weight polyethylene glycol. This composition is far less vulnerable to the deterioration that occurs as dendroid voids when employed as an electrical insulation of high-tension power cables which are operated under water. The polyethylene glycol has more than 44 carbon atoms and is used in an amount from 0.3 to 10 wt% based on polyolefin.

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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

  • Granted February 26, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 26, 2002.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJune 5, 1981
GrantedFebruary 26, 1985
Term endedFebruary 26, 2002
Patent numberCA 1183297 A
Classification (IPC)H01B3/44 +2 more

Timeline

Timeline From CIPO dates

1982198519881991199419972000Application filedJune 5, 1981Patent grantedFeb 26, 1985Term endedFeb 26, 2002

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.