PURPOSE: To obtain the titled board having excellent punchability, electric properties, and heat resistance, by impregnating and thermally compressing a base board with varnish prepared from an adduct of polybutadiene/amine and resol- type phenol resin.
CONSTITUTION: A base board is impregnated with phenol resin varnish prepared by blending A and B in a ratio of 5W150: 100 (A is prepared by adding amine to polybutadiene of number-average MW 500W3,000 and adjusting an amino value of the adduct at 10W200 and B is a resol-type phenol resin). A laminated board is prepared by drying a base board impregnated with the varnish and by effecting thermal compression therafter. If the mumber-average MW of the polybutadiene is ≤500 a punchability is poor because of the low flexibility, and if ≥3,000, the MW of the amine adduct tends to be ≥5,000, thus impregnability for papers tends to be unfavorably lowered.
TOKOU AKIRA
TAKEDA NAOJI
