Tire Sidewall Rubber Blend for Ozone Resistance and Diene Adhesion
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Solution Overview
Problem
Conventional rubber compositions for tire sidewalls face challenges in achieving sufficient flexibility, ozone resistance, and adhesion to diene compositions, particularly when the molar rate of ethylene in diene copolymers is greater than 50%, which affects the tire's lifespan and performance.
Innovation Solution
A rubber composition comprising 5 to 95 phr of polyisoprene with 1,4-cis bonds of at least 90% and a copolymer of ethylene and a 1,3-diene, where ethylene units represent more than 50% of the monomer units, along with a crosslinking system, to enhance adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ethylene-rich diene copolymer is used to improve ozone resistance, then ozone resistance is improved, but adhesion to diene composition deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating a specific 1,3-diene component with 3-20 carbon atoms in the copolymer structure, and adjusts the sulfur content to 2-10 phr to optimize both ozone resistance and adhesion properties simultaneously
Solution Approach 2:
The patent creates a composite rubber composition combining ethylene-rich diene copolymer with polyisoprene and specific additives, forming a multi-component system that achieves both ozone resistance and improved adhesion to diene compositions
2Ease of operation
If sidewall composition is made flexible to withstand deformation cycles, then flexibility is improved, but adhesion to carcass reinforcement deteriorates
Solution Approach 1:
The patent adjusts the compositional parameters including the ratio of copolymer to polyisoprene, sulfur content (2-10 phr), and the specific 1,3-diene structure to achieve an optimal balance between flexibility for deformation resistance and adhesion to carcass reinforcement
3Reliability
If sulfur content is increased to improve adhesion, then adhesion is improved, but curing time increases
Solution Approach 1:
The patent optimizes the sulfur content parameter to a specific range of 2-10 phr, which provides sufficient adhesion while avoiding excessive curing times, representing an optimized parameter setting that balances both requirements
Data Source
AI summary
The invention relates to a rubber composition having adhesion to a natural rubber composition, said composition being at least based on 5 to 95 phr of polyisoprene having a percentage by weight of 1,4-cis bonds of at least 90% of the weight of the polyisoprene; 5 to 95 phr of ethylene copolymer and of a 1,3-diene of formula CH2=CR-CH=CH2, wherein the ethylene units in the copolymer represent more than 50 mol% of the monomer units of the copolymer, the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms; and a crosslinking system. The invention also relates to a pneumatic tire, in particular a pneumatic tire provided with a sidewall comprising said composition.