Transmission Belt Rubber Composition for Scorch and Rolling Control
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Solution Overview
Problem
Existing rubber compositions for power-transmission belts face issues with scorching, rolling difficulty, and inadequate mechanical properties and durability, particularly when using ethylene-α-olefin elastomers, despite attempts to improve these properties with carbon black and short fibers.
Innovation Solution
A rubber composition combining ethylene-α-olefin elastomer with low Mooney viscosity, carbon black, and clay with a pH of 5.5 or higher, at specific proportions, along with optional short fibers, to enhance rolling ease and mechanical properties while preventing scorching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon black and short fibers are added to improve mechanical properties, then strength and durability are improved, but rolling processability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the rubber system by introducing a specific polyfunctional crosslinking agent that reacts with hydroxyl groups. This allows achieving the desired mechanical properties through chemical crosslinking rather than relying on excessive carbon black and short fiber additions, thereby maintaining rolling processability.
Solution Approach 2:
The patent creates a composite rubber composition combining ethylene-α-olefin elastomer with a polyfunctional crosslinking agent that forms a three-dimensional crosslinked structure. This composite system achieves enhanced mechanical properties through controlled crosslinking while avoiding the processing issues associated with high filler content.
2Strength
If crosslinking is promoted to improve mechanical properties, then strength is improved, but scorching occurs during processing
Solution Approach 1:
The patent incorporates a hydroxyl group-containing compound during rubber compounding, which pre-prepares reactive sites for subsequent crosslinking. This preliminary action allows controlled crosslinking to occur only under specific processing conditions, preventing premature scorching during mixing and forming operations.
Solution Approach 2:
The hydroxyl group-containing compound acts as an intermediary that mediates between the rubber matrix and the polyfunctional crosslinking agent. It provides controlled reaction sites that enable gradual crosslinking under controlled conditions, preventing sudden scorching while ensuring complete crosslinking for optimal mechanical properties.
Data Source
AI summary
A rubber composition for a power-transmission belt includes: a polymer component including an ethylene-α-olefin elastomer; carbon black; and clay, in which the ethylene-α-olefin elastomer has a Mooney viscosity at 125° C. of 25 ML (1+4) 125° C. or less, the clay has a pH of 5.5 or higher, a total amount of the carbon black and the clay is 80 parts by mass to 180 parts by mass with respect to 100 parts by mass of the polymer component, and a mass ratio of the carbon black to the clay is clay/carbon black=0.2/1 to 1.2/1.