| 摘要 |
PURPOSE:To prevent discoloration, by forming the side wall part of a pneumatic tire to have a two-layer structure, blending the surface layer thereof can be inner layer thereof with a specified amount of a p-phenylenediamine antioxidant and specifying the ratio of the surface layer to the inner layer. CONSTITUTION:The side wall part 2 of a pneumatic tire provided with a tread 1, a side wall 2 and a bead 3 is of a two-layered structure composed of a surface layer 2a and an inner layer 2b in a ratio of the thickness of the surface layer to that of the inner layer of 3/1-1/3. Each of the surface layer and the inner layer is composed of a natural rubber or a synthetic diene rubber 100pts. wt. rubber of the surface layer is blended with 0.1-10pts.wt. p-phenylenediamine antioxidant of the formula wherein R and R' are each H or an alkyl and the sum of carbon atoms of R and R' is 3-19). 100pts.wt. rubber for the inner surface is blended with 0.1-10pts.wt. antioxidant of the formula (wherein the sum of carbon atoms of R and R' is 7-19). The ratio of the amount of the antioxidant in the surface layer to that in the inner layer is 1/1-1/5.
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