Sumitomo Bakelite Company Limited

Shoroku Kaneko

Sigenori Yamaoka

Masuo Mizuno

Yukihiro Okabe

A crosslinked resin excellent in heat resistance, toughness, moisture resistance and adhesiveness can be obtained by the use of an epoxy compound having both alcoholic hydroxyl groups and epoxy groups in its molecule and an isocyanate compound having isocyanate groups in its molecule by first reacting the alcoholic hydroxyl groups of said epoxy compound and the isocyanate groups of said isocyanate compound to produce an epoxy prepolymer having urethane linkages stable at room temperature, followed by dissociating the urethane linkages of the prepolymer to regenerate the isocyanate groups and reacting said isocyanate groups with the epoxy groups of said epoxy compound. By carrying out the above-mentioned reaction between the isocyante groups and the epoxy groups in the presence of at least one member selected from the group consisting of amine compounds, carboxylic acid anhydrides, phenol novolac compounds and polyvinyl-phenol compounds and/or a bisimide compound, a crosslinked resin having higher heat resistance can be produced. Said prepolymer is excellent in storage stability and suitable for use in the production of laminates.

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Yokosuka, Japan

Shoroku Kaneko