PURPOSE: To obtain the titled easily controllable laminated sheet having high stability at a low cost, by coating a substrate with a phenolic polymer varnish produced by using a specific reactive solvent and polymerizing the reactive solvent at a prescribed temperature to obtain a prepreg.
CONSTITUTION: A phenolic polymer varnish is produced by dissolving a phenolic polymer in a radically polymerizable reactive solvent (preferably a combination of a monofunctional compound with a compound having ≥2 functionality) added with a low-temperature decomposition type radical polymerization initiator (e.g. 2,2'-azobisisobutyronitrile). The varnish is coated to and impregnated in a substrate for laminated sheet and the reactive solvent is polymerized at ≤120°C to obtain a prepreg. A prescribed number of the prepreg sheets are stacked one upon another, a copper foil is placed thereon as necessary, and the laminate is hot-pressed to obtain the objective laminated sheet. The amount of the low-temperature decomposition radical polymerization initiator is preferably 0.05W15wt.% based on the varnish.
YAMAMOTO KAZUNORI
YASUZAWA KOHEI
YOSHIMURA YUKIO
