Rubber Composition Hardness Stability at Elevated Vulcanization Temperatures
Solution Overview
Problem
Rubber compositions face vulcanization temperature dependency issues, where hardness decreases with increased vulcanization temperature, limiting the simultaneous improvement of hardness and low heat build-up properties in tire rim cushions.
Innovation Solution
A rubber composition is developed with specific amounts of two kinds of carbon black having distinct nitrogen adsorption specific surface areas, sulfur, and a sulfenamide-based vulcanization accelerator in diene rubber, which maintains hardness and physical breakage properties across varying vulcanization temperatures without deteriorating heat build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vulcanization temperature is increased to improve processing efficiency, then the productivity is improved, but the hardness of the rubber decreases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the vulcanization temperature within a specific range (160-180°C) and adjusting the sulfur content (1.5-2.2 parts by mass) and accelerator ratio (110-200 mass%) to achieve optimal hardness without excessive temperature increase, thereby maintaining both productivity and hardness
Solution Approach 2:
The patent uses composite materials by combining diene rubber with specific proportions of isoprene rubber (30-60 parts by mass) and butadiene rubber (40-70 parts by mass), along with carbon black and sulfur compounds, to create a vulcanizable rubber composition that maintains hardness at moderate vulcanization temperatures
2Strength
If the hardness is improved by adjusting composition, then the rim cushion support capability is improved, but the heat build-up increases
Solution Approach 1:
The patent controls the nitrogen adsorption specific surface area of carbon black within 20-80 m2/g and adjusts the sulfur content and accelerator ratio to achieve the desired hardness while minimizing heat build-up through optimized chemical composition rather than excessive temperature increase
Solution Approach 2:
The patent employs composite materials by combining specific ratios of isoprene rubber, butadiene rubber, and carbon black with controlled surface area to create a rubber composition that achieves high hardness with low heat build-up characteristics
3Reliability
If the sulfur content is increased to improve physical breakage properties, then the reliability is improved, but the heat build-up increases
Solution Approach 1:
The patent optimizes the sulfur content within a specific range (1.5-2.2 parts by mass) and adjusts the accelerator ratio (110-200 mass% relative to pure sulfur content) to achieve excellent physical breakage properties while controlling heat build-up through precise compositional parameters
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 effectively suppresses vulcanization temperature dependency, maintaining consistent hardness and improving physical breakage properties while preventing heat build-up, making it suitable for tire rim cushions.
Implementation Method 1
carbon black having a nitrogen adsorption specific surface area
Implementation Method 2
from 1.5 to 2.2 parts by mass of sulfur as a pure sulfur content, and from 110 to 200 mass % of a sulfenamide-based vulcanization accelerator relative to the pure sulfur content in 100 parts by mass of diene rubber
Data Source
AI summary
The present technology provides a rubber composition having: from 30 to 50 parts by mass of carbon black having a nitrogen adsorption specific surface area of from 100 to 130 m2/g, from 25 to 40 parts by mass of carbon black having a nitrogen adsorption specific surface area of from 37 to 60 m2/g, from 1.5 to 2.2 parts by mass of sulfur as a pure sulfur content, and from 110 to 200 mass % of a sulfenamide-based vulcanization accelerator relative to the pure sulfur content compounded in 100 parts by mass of diene rubber containing from 30 to 60 parts by mass of isoprene rubber and from 40 to 70 parts by mass of butadiene rubber.