Evaluation of Antidegradants Systems for Enhancing Performance of Bromobutyl Based Tire Innerliners

Abstract

                 Bromobutyl (BIIR) is an elastomeric isobutylene–isoprene copolymer containing reactive bromine.  Bromobutyl polymer exhibit most of the attributes of the butyl polymer molecule because of the predominately saturated polyisobutylene backbone of butyl rubber. These attributes include physical strength, vibration damping, low permeability, and resistance to aging and weathering from environmental exposure.

             The modern radial tire, in many respects, is made possible through the introduction and use of halobutyl rubber innerliners. Use of bromobutyl in the tire innerliner compound has allowed improvements in air retention performance, liner-to-tire casing adhesion, and tire durability. Tire sidewall is another major application for halobutyl rubber. Use of halobutyl in sidewalls enhances the sidewall fatigue life and can also reduce sidewall staining. Fatigue properties of innerliner and sidewall compound are very critical for tire performance (both the initial life as well as life after retread). Tire manufacturers are actively looking for ways and means to improve the fatigue properties of these compounds.

             Bromobutyl compounds, with the low functionality and almost completely saturated polymer backbone, generally do not require additional antioxidant or antiozonants for enhancing the fatigue life. If antidegradants are to be added for severe exposure conditions or for use in blends with highly unsaturated rubbers, their selection is suggested to be done after proper review. 

       This review explores the effect of using different types of antioxidants and antireversion agents in bromobutyl based tire innerliner compound. The study includes evaluation of Amine type of antioxidants, Phenolic antioxidants, and anti reversion agents, (1, 3 bis (citraconimido-methyl) benzene (BCI –MX)).

       This study assumes significance as it provides basic insight on how to protect bromobutyl vulcanizate from the degrading influence of heat, oxygen and ozone.