Abstract: A method is disclosed for adhering rubber and reinforcing materials simultaneously with vulcanization, without defects such as fume and bloom phenomena of formaldehyde-acceptors, deliquescence and blocking, which is characterized in the use of a vulcanizable rubber composition containing an improved co-polycondensate resin which is prepared by condensing (A) a resol type pre-polycondensate prepared by at least one phenol and formaldehyde or acetaldehyde in the presence of an alkaline catalyst, and (B) resorcinol, m-aminophenol or the like, while distilling off water present in the reaction system, and then solidifying the reaction mixture.

Abstract: Rubbers are prevented from ozone deterioration without discoloring or staining by the addition of a nitrile of the formula, ##STR1## wherein R.sub.1 and R.sub.2 are each hydrogen, C.sub.1 - C.sub.24 aliphatic, C.sub.5 - C.sub.7 alicyclic or aryl, or R.sub.1 and R.sub.2 may form together with the adjacent nitrogen atom a heterocyclic group which may further contain oxygen, and R.sub.3 and R.sub.4 are each hydrogen or lower alkyl.