MANUFACTURE OF PLASTIC LENS
PURPOSE:To obtain lens with no optical strain at high yield by a method wherein ethylene copolymer having specified flexural modulus of elasticity and Vicat softening point is empolyed as gasket used for assembling molds at the manufacturing of a plastic lens, which is performed by irradiating photo...
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Zusammenfassung: | PURPOSE:To obtain lens with no optical strain at high yield by a method wherein ethylene copolymer having specified flexural modulus of elasticity and Vicat softening point is empolyed as gasket used for assembling molds at the manufacturing of a plastic lens, which is performed by irradiating photopolymerizable monomer in molds with active energy beam. CONSTITUTION:As the stock of a gasket 3, with which a pair of mold members 1 and 2 are assembled, ethylene copolymer having the flexural modulus of elasticity of 500-100kg/cm and the Vicat softening point of 35-65 deg.C is employed. By employing the gasket 3, no separation of a lens from the molds 1 and 2 occurs, resulting in obtaining a lens with no optical strain. As the copolymer satisfying the above-mentioned conditions, copolymer of ethylene and 6-12mol.% of lower alkanoic acid vinyl ester and copolymer of ethylene and 6-12mol.% of lower alkyl acrylate are exampled. |
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