| 摘要 |
PROBLEM TO BE SOLVED: To obtain a laminated sheet hard to generate a silver transfer phenomenon by laminating and molding paper base materials impregnated with a phenol resin compounded with an inorg. filler having a specific particle size. SOLUTION: Paper base materials impregnated with a phenol resin compounded with an inorg. filler with a particle size of 1-50μm are laminated to be molded. In this way, a laminated sheet enhanced in the humidity resistance of paper fibers, made hard to generate water absorption from its surface by the inorg. filler floccurated on a paper surface and having high silver transfer resistance is obtained. As the inorg. filler to be used, aluminum oxide, talc, calcium carbonate, clay, antimony trioxide, boric acid or zinc borate are designated. Especially, aluminum hydroxide and boric acid are pref. in order to enhance fire retardancy or punching properties. The addition amt. of the inorg. filler is desirably 1-50 pts.wt. per 100 pts.wt. of the base materials.
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