Heat-resistant methacrylic copolymers, production process thereof and optical elements
US6716951B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 2002 |
| Grant date | Apr 6, 2004 |
| Priority date | — |
| Expiry date | Jul 22, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B1/04
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process for production of methacrylic copolymers, characterized by charging a monomer mixture comprising from 70 to 95% by weight of methyl methacrylate, from 0 to 15% by weight of &agr;-methylstyrene, from 0 to 20% by weight of styrene and from 2 to 15% by weight of maleic anhydride at a molar ratio of the sum of &agr;-methylstyrene and styrene to maleic anhydride laying within the range of 1.0 to 2.5 into a polymerizing vessel containing at least one polymeric membrane layer having an oxygen permeability of 1.5×10−13 (mol·m−2·s−1·Pa−1) or below, sealing the polymerizing vessel, and polymerizing the monomer mixture under heating in a gas phase; a methacrylic copolymer obtained by the production process which is reduced yellowing and shows excellent transparency and heat resistance; and an optical element composed of the methacrylic copolymer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.