Base Tread Rubber Composition Using Dual Fillers for Steering Stability
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Solution Overview
Problem
Conventional rubber compositions for base treads face challenges in balancing steering stability and low heat generation properties while maintaining durability, as increasing filler content improves hardness but deteriorates low heat generation properties, and decreasing filler content compromises steering stability.
Innovation Solution
A rubber composition for base treads comprising a rubber component with 70% natural rubber, a first filler of carbon black with a nitrogen adsorption specific surface area of less than 60 m2/g, a second filler of carbon black or silica with a nitrogen adsorption specific surface area of 60 m2/g or more, sulfur, and a sulfenamide-based vulcanization accelerator, with specific mass ratios and contents to enhance steering stability and low heat generation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of filler is increased to improve hardness and steering stability, then steering stability is improved, but low heat generation properties deteriorate
Solution Approach 1:
The filler is segmented into two distinct types with different nitrogen adsorption specific surface areas: first filler (carbon black with N2SA < 60 m2/g) and second filler (carbon black with N2SA ≥ 60 m2/g or silica). This segmentation allows each filler type to contribute differently to the overall performance, with the first filler providing hardness and steering stability while the second filler helps control heat generation properties.
Solution Approach 2:
The invention changes the parameter of nitrogen adsorption specific surface area to differentiate between filler types. By specifying that the first filler has N2SA < 60 m2/g and the second filler has N2SA ≥ 60 m2/g, the patent optimizes the balance between hardness (improved by lower N2SA fillers) and low heat generation properties (improved by higher N2SA fillers).
2Loss of energy
If the amount of filler is decreased to improve low heat generation properties, then low heat generation properties are improved, but steering stability deteriorates
Solution Approach 1:
The filler composition is segmented into two functional components: first filler (carbon black with N2SA < 60 m2/g) that primarily provides steering stability, and second filler (carbon black with N2SA ≥ 60 m2/g or silica) that primarily controls heat generation. This segmentation enables independent optimization of both steering stability and low heat generation properties.
Solution Approach 2:
The invention uses a composite filler system combining two types of carbon black with different N2SA values, or carbon black with silica. This composite approach allows the rubber composition to simultaneously achieve good steering stability (from the first filler) and improved low heat generation properties (from the second filler), neither of which could be achieved with a single filler type alone.
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 composition achieves improved steering stability and low heat generation properties while suppressing deterioration of durability, as demonstrated by enhanced hardness, reduced heat generation, and maintained tear strength.
Implementation Method 1
carbon black having a nitrogen adsorption specific surface area of less than 60 m2/g
Data Source
AI summary
A rubber composition for a base tread according to an embodiment includes a rubber component containing 70 mass % or more of natural rubber, a first filler that is carbon black having an N2SA of less than 60 m2/g, a second filler that is carbon black having an N2SA of 60 m2/g or more and/or silica, sulfur, and a sulfenamide-based vulcanization accelerator. Per 100 parts by mass of the rubber component, the amount of the first filler is 10 to 45 parts by mass, the amount of the second filler is 15 to 30 parts by mass, the total amount of the first filler and the second filler is 35 to 60 parts by mass, the amount of the sulfur is 1.6 to 3.0 parts by mass, and the amount of the sulfenamide-based vulcanization accelerator is 1.6 to 3.0 parts by mass.