Tire Inner-Layer Rubber Composition Ozone Resistance
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Solution Overview
Problem
Conventional rubber compositions for tire inner layers face challenges in providing excellent ozone resistance over a wide environmental temperature range while preventing discoloration, particularly in cold and hot regions, and in maintaining sufficient static ozone resistance and brown discoloration resistance in thinner outer rubber layers.
Innovation Solution
A rubber composition for tire inner layers containing C20 to C32 normal alkanes in a combined amount of 0.1 to 2.5 parts by mass, along with phenylenediamine and quinone antioxidants, is used, which provides excellent ozone resistance and prevents discoloration across various temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wax is used in an amount that allows prevention of discoloration, then discoloration resistance is improved, but ozone resistance in cold environments deteriorates
Solution Approach 1:
The patent changes the molecular weight parameter of the wax from conventional high molecular weight (C40+) to specific lower molecular weight ranges (C20-C35), which fundamentally alters the blooming and migration characteristics of the wax, enabling effective ozone resistance in cold environments without excessive discoloration
Solution Approach 2:
The patent uses composite wax formulations combining different normal alkane components (C20-C35) with specific molecular weight distributions, creating a synergistic effect that provides both cold environment ozone resistance and acceptable discoloration performance
2Reliability
If conventional wax is used in sufficient amount to ensure ozone resistance in hot regions, then ozone resistance is improved, but white discoloration increases
Solution Approach 1:
The patent optimizes the molecular weight parameter of the wax to C20-C35 range, which has lower blooming tendency compared to conventional high molecular weight waxes, thereby reducing white discoloration while maintaining effective ozone resistance in hot regions
3Weight of moving object
If outer rubber layers are thinned to reduce tire weight, then weight is reduced, but static ozone resistance and brown discoloration resistance deteriorate
Solution Approach 1:
The patent applies antioxidant compounds (6PPD, 77PD, 6QDI) and specific wax (C20-C35 normal alkanes) in advance to the outer rubber layers, creating a protective barrier that provides sufficient static ozone resistance and brown discoloration resistance even when the outer layers are thinned
Solution Approach 2:
The patent changes the composition parameters of the outer rubber layers by incorporating specific antioxidants and low molecular weight waxes, which provide enhanced protective functions at reduced thickness
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 rubber composition effectively offers excellent ozone resistance and prevents discoloration over a wide environmental temperature range, ensuring the durability and performance of tire inner layers and pneumatic tires.
Implementation Method 1
The added wax migrates to the rubber surface to form a film on the rubber surface, which physically protects rubber from physical stimuli of ozone, oxygen, and other harmful gases
Implementation Method 2
Wax is mainly formed of normal alkanes -(CH 2 ) (molecular weight: 14), and has a molecular weight of approximately 420 [= (number of repeating alkane units) (=30) × (unit molecular weight) (=14)], which is approximately equivalent to that of the process oil TDAE. Thus, its migration rate to adjacent rubbers can be considered to be equivalent to that of oil.
Data Source
AI summary
The invention provides rubber compositions for tire inner layers, capable of providing excellent ozone resistance over a wide environmental temperature range and of preventing discoloration well, as well as pneumatic tires including such compositions. The invention relates to a rubber composition for tire inner layers, containing C20-C32 normal alkanes. Preferably, the combined amount of the C20-C32 normal alkanes is 0.1-2.5 parts by mass, and the combined amount of phenylenediamine and quinone antioxidants is 0-4 parts by mass, each per 100 parts by mass of the diene rubber component. The rubber composition for tire inner layers preferably contains C48 and higher normal alkanes in a combined amount of not more than 0.1 parts by mass per 100 parts by mass of the diene rubber component. The rubber composition preferably contains not more than 15 parts by mass of process oil per 100 parts by mass of the diene rubber component.