PHENOLIC RESIN COMPOSITION

PROBLEM TO BE SOLVED: To obtain a phenolic resin compsn. which is excellent in resistances to moisture and heat, flame retardance, and electrical characteristics though it does not contain a halogenous flame retardant by compounding a phenol- formaldehyde resin as the major ingredient with flame retardants comprising an inorg. filler capable of dissociating water of crystallization and melamine cyanurate. SOLUTION: This compsn. is prepd. by compounding 100 pts.wt. phenol- formaldehyde resin with, as flame retardants, 5-20 pts.wt. inorg. filler capable of dissociating water of crystallization (e.g. boric acid, aluminum hydroxide, zinc borate, magnesium hydroxide, or talc) and 3-20 pts.wt. melamine cyanurate. Usually, a novolak phenolic resin is used as the phenol-formaldehyde resin, and hexamethylenetetramine is used as the curative. The joint use of an inorg. filler capable of dissociating water of crystallization and melamine cyanurate draws out the characteristics of both the flame retardants and synergistically improves the flame retardance of the compsn.