Patent ID: 8101679

Claim:
An improved method for the preparation of rubber compounds which comprises compounding rubber, epoxidised soybean oil and 2,2,6,6-tetramethylpiperidine-1-oxy at 125-200° C. in the presence of an amount of 0.1-2%, based on the weight of the rubber, of a processing stabilizer of the formula I wherein R 1 is hydrogen, C 1 -C 20 alkyl, styryl, α-methyl-styryl or —CH 2 —S—R 3 ; or C 1 -C 20 alkyl substituted with C 2 -C 20 alkenyl, C 3 -C 20 alkinyl, C 5 -C 9 cycloalkyl, phenyl or tolyl; R 2 is C 1 -C 20 alkyl or —CH 2 —S—R 3 , R 3 is C 1 -C 20 alkyl; C 1 -C 20 alkyl substituted with phenyl, hydroxyl, cyano, formyl, acetyl or —O—CO—R 5 ; C 2 -C 20 alkenyl, C 3 -C 20 alkinyl, C 5 -C 9 cycloalkyl; or C 5 -C 9 cycloalkyl substituted with hydroxyl, phenyl, 4-chlorophenyl, 2-methoxycarbonylphenyl, p-tolyl, 1,3-benzthiazol-2-yl, —(CHR 5 ) n COOR 6 or —(CHR 5 ) n CONR 7 R 8 ; R 4 is hydrogen or methyl, R 5 is hydrogen or C 1 -C 6 alkyl, R 6 is C 1 -C 20 alkyl; C 3 -C 20 alkyl interrupted with oxygen or sulfur; C 5 -C 9 cycloalkyl, phenyl, benzyl or tolyl, R 7 and R 8 are independently of each other hydrogen or C 1 -C 6 alkyl, and n is 1 or 2, where the weight ratio of the stabilizer of formula I to the epoxidised soybean oil is from 99.5:0.5 to 10:90 and where the weight ratio of the stabilizer of formula I to 2,2,6,6-tetramethylpiperidine-1-oxyl is from 2:1 to 1:2.