Electret sheet and piezoelectric sensor
US9831040B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 10, 2015 |
| Grant date | Nov 28, 2017 |
| Priority date | — |
| Expiry date | Mar 10, 2035 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2323/14
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The present invention provides an electret sheet which can maintain a high generated voltage even if a large amount of pressure has been applied. Disclosed is an electret sheet of the present invention including an electrically charged propylene-based resin foam sheet which contains a crosslinked propylene-based resin that includes a propylene-α-olefin random copolymer having a weight average molecular weight of 370,000 to 420,000 at a proportion of 60% by weight or more, and has a gel fraction of 30% to 50% by weight, and in which the average thickness is 90 to 150 μm, and the average number of foam cells in the thickness direction is 2 to 4 cells.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.