| 摘要 |
PROBLEM TO BE SOLVED: To prepare the subject resin composition capable of improving elongation at break of rubber (especially a rubber composition for tire tread) by making the composition include a phenolic novolak resin together with an epoxy resin having plural epoxy groups. SOLUTION: This resin composition comprises (A) a phenolic novolak resin and (B) an epoxy resin having at least two epoxy groups in a molecule. The content ratio of the hydroxyl group of the ingredient A to the epoxy group of the ingredient B is preferably 0.2-5.0. A curing accelerator for the ingredients A and B is e.g. hexamethylenetetramine, a tertiary amine or the like and is preferably an imidazole and an organic phosphine compound. The composition having 1.0 content ratio (hydroxyl group/epoxy group) and 83 deg.C softening point is produced e.g. by the heat melting of 175 pts.wt. unmodified solid phenolic novolak resin (having 120 deg.C softening point and including 3% free phenol) together with 825 pts.wt. solid bisphenol A epoxy resin (having 65 deg.C softening point and 475 epoxy equivalent) in a reactor.
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