| 摘要 |
PURPOSE:To improve the balance of heat resistance and mechanical property as well as dimensional stability by specifying the average mol.wt. of a polyphenylene ether part with the ultimate viscosity (measured with a chloroform soln. at 25 deg.C). CONSTITUTION:An optical element is constituted of a mixture composed of a polymer essentially consisting of an arom. vinyl monomer unit and polyphenylene ether, a block copolymer consisting of the polymer part of both or graft copolymer or a mixture composed thereof. The average mol.wt. of the polyphenylene ether is preferably 0.3-0.7 when expressed by the ultimate viscosity (value measured with the chloroform at 25 deg.C). The ratio of the polymer part essentially consisting of the arom. vinyl monomer unit and the polyphenylene ether part is preferably 40-55wt% the former and 45-60wt% the latter. The double refraction of the optical element does not decrease thoroughly if the polyphenylene ether part is <40wt% or exceeds 70wt%. The heat resistance is not satisfactory if said part is <40wt%. |
