Vulcanizable rubber compositions containing urethane modified novolak for increasing the adhesion to steel cords and the stiffness

摘要

A urethane modified novolak (I) is prepared by simultaneous reaction of (A) a mono or multivalent phenol with (B) an oxo-compound, preferably an aldehyde or ketone and (C) a urethane in the presence of (D) an acid catalyst at 60-200 degrees C. (I) does not contain a significant amount of free phenol.