Patent · US Expired

Electrets

US6489033B1 · kind B1 · utility

10Cited by

2References

13Claims

0Family size

Assignee

Ticona LLC · US

Inventors

Wilfried Hatke · Hofheim, DE
Gerhard Sessler · Summit, US
Guo-Mao Yang · Kingston, CA

Key dates

Filing date	Feb 28, 2000
Grant date	Dec 3, 2002
Priority date	—
Expiry date	Feb 28, 2020

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10T428/31855
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

Electrets can be produced from cycloolefin copolymers (COCs), and charges applied thereto are stable for long periods, even at high temperatures and high relative humidities. The reduction here in a positive charge applied to the COCs is smaller than that of negative charges applied to the COCs. The stability over time of the charges applied is impaired by adding polar additives, such as inorganic silicon compounds. Films, fibers or nonwovens produced from electrets can be processed to give filters.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.