Cyclic Polysulfide Vulcanization for Heat Aging and Fatigue Resistance
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Solution Overview
Problem
Conventional pneumatic tire rubber compositions face challenges in achieving balanced properties such as heat aging resistance, heat buildup, fatigue resistance, grip performance, and durability due to limitations in vulcanization agents and cross-linking methods, which affect the tire's performance and longevity, especially in high-speed and run-flat applications.
Innovation Solution
A rubber composition using cyclic polysulfides as a vulcanization agent, replacing conventional sulfur, to enhance the vulcanized rubber's properties, including heat aging resistance, fatigue resistance, and grip performance, by blending cyclic polysulfides with sulfur-vulcanizable rubbers and other additives to achieve improved physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional sulfur vulcanization is used, then the rubber achieves basic cross-linking, but the heat resistance and vulcanization reversion are poor
Solution Approach 1:
The patent changes the chemical composition parameters of the vulcanization agent from conventional sulfur to cyclic polysulfide with specific molecular structure (formula I), where the cyclic structure and polysulfide bonds provide superior heat resistance and prevent vulcanization reversion while maintaining cross-linking efficiency
Solution Approach 2:
The patent uses a composite vulcanization system combining cyclic polysulfide (component B) with sulfur (component C) in specific ratios, creating a synergistic effect where cyclic polysulfide provides heat stability and sulfur contributes to cross-linking density, resolving the contradiction between heat resistance and vulcanization reversion
2Temperature
If EV cross-linking with large amount of vulcanization accelerator is used to improve heat aging resistance, then the ratio of polysulfide bonds is reduced, but the dynamic fatigue resistance becomes inferior
Solution Approach 1:
The patent changes the vulcanization mechanism by using cyclic polysulfide as the primary agent, which maintains high polysulfide bond content (x=2-6 in formula I) while achieving excellent heat aging resistance, eliminating the need to reduce polysulfide bonds through EV cross-linking and thereby preserving dynamic fatigue resistance
Solution Approach 2:
The patent replaces expensive vulcanization accelerators with cyclic polysulfide, which provides both heat aging resistance and maintains polysulfide bond structure, offering a more sustainable and effective solution than conventional accelerator-based EV cross-linking
3Strength
If large amounts of filler are used to improve abrasion resistance or grip, then the tensile strength increases, but the grip sustainability deteriorates due to tread degradation
Solution Approach 1:
The patent creates a composite vulcanization system with cyclic polysulfide and sulfur that produces a more stable cross-linked network, reducing tread hardening and degradation over time while maintaining high tensile strength from filler content, thereby improving grip sustainability without sacrificing strength
Solution Approach 2:
The patent optimizes the vulcanization agent composition to achieve a balanced cross-linking structure that maintains flexibility and grip characteristics over time, preventing the tread from becoming too hard and losing grip sustainability while retaining the strength benefits of high filler content
4Temperature
If high cross-linking density is used to improve heat resistance in run-flat tires, then the hardness increases, but the elongation at break decreases
Solution Approach 1:
The patent optimizes the cyclic polysulfide structure parameters (x=2-6, specific R groups in formula I) to achieve optimal cross-linking density that provides sufficient heat resistance while maintaining adequate elongation at break, avoiding excessive hardening that would compromise run-flat performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cyclic polysulfide-based rubber composition demonstrates enhanced heat aging resistance, improved fatigue resistance, and sustained grip performance, enabling better durability and performance in high-speed and run-flat conditions without compromising rolling resistance or steering stability.
Implementation Method 1
a rubber composition comprising (A) 100 parts by weight of a sulfur-vulcanizable rubber and (B), as a vulcanization agent, 0.1 to 30 parts by weight of a cyclic polysulfide
Data Source
AI summary
A rubber composition containing 100 parts by weight a sulfur-vulcanizable rubber (A) and 0.1 to 30 parts by weight of a vulcanization agent of a cyclic polysulfide (B) having the formula (I):wherein R is a substituted or unsubstituted C2 to C20 alkylene group, substituted or unsubstituted C2 to C20 oxyalkylene group or alkylene group having an aromatic ring, n is an integer of 1 to 20, x is a number of 2 to 6 on average.