PURPOSE: To enable efficient use of mold and characteristics of easy mold release, by mold releasing at the time when the glass transition temperature of plastic substrate obtained by radical polymerization of multi-functional acrylate compound in a mold reaches a specific temperature, then in addition by post-curing this substrate.
CONSTITUTION: The glass transition temperature at the time of mold release of the transparent plastic substrate obtained by radical polymerization in case molding process of multi-functional acrylate showed in formula (I) is set 10W100°C. For his purpose the time for radical polymerization in mold is less than 2hr, preferably less than 1hr. Mold-released plastic substrate is put at a flat place and post-cured by ultra-violet radiation, etc., to the extent that Tg is more than 110°C. Thus the substrate radical-polymerized and pre-cured in the mold is post-cured at the outside of the mold, therefore the production amount of the substrate per one mold is raised. Additionally the damage of the substrate hardly occurs because pre-cured substrate is mold-released in the state that glass transition temperature is low.
SAKAIRI TADASHI
ARITOMI MITSUTOSHI
TAKEYAMA TADAO
MATSUSHITA ELECTRIC IND CO LTD
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