Nitrile Rubber Composition with Low Viscosity Elastomer
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Solution Overview
Problem
Existing nitrile group-containing highly saturated copolymer rubber compositions face challenges in achieving high tensile stress and low heat buildup properties while maintaining excellent workability, particularly due to issues with dispersibility of staple fibers and compatibility with softeners and low viscosity liquid rubbers.
Innovation Solution
A composition comprising a high Mooney viscosity nitrile group-containing highly saturated copolymer rubber, a low Mooney viscosity nitrile group-containing highly saturated copolymer rubber, and staple fibers with specific average fiber length, along with an α,β-ethylenically unsaturated carboxylic acid metal salt, to enhance tensile stress and low heat buildup properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a large amount of softener is mixed in to make staple fibers disperse in the rubber composition, then the dispersability of staple fibers is improved, but bleeding occurs and the obtained cross-linked rubber becomes insufficient in tensile stress and low heat buildup property
Solution Approach 1:
The patent uses a specific softener (dioctyl phthalate or dibutyl phthalate) as an intermediary substance that facilitates fiber dispersion without causing bleeding. This mediator enables the staple fibers to disperse properly in the rubber composition while maintaining the mechanical properties and heat buildup characteristics of the cross-linked rubber.
Solution Approach 2:
The patent changes the parameters of the softener selection, specifically choosing softeners with molecular weights of 200 or more (preferably 250-400) and specific chemical structures (phthalate esters). This parameter change allows sufficient fiber dispersion while preventing bleeding and maintaining the required mechanical properties.
2Ease of operation
If liquid rubber with very low viscosity (Mooney viscosity substantially 1 or less) is used to improve workability, then the workability is improved, but the obtained cross-linked rubber is not sufficient in tensile stress and low heat buildup property
Solution Approach 1:
The patent changes the viscosity parameter of the liquid rubber from extremely low (Mooney viscosity substantially 1 or less) to a controlled low range (Mooney viscosity of 5-30). This parameter adjustment maintains good workability while ensuring sufficient tensile stress and low heat buildup properties in the cross-linked rubber.
3Strength
If high Mooney viscosity nitrile group-containing highly saturated copolymer rubber is used to improve tensile stress, then the tensile stress is improved, but the workability deteriorates
Solution Approach 1:
The patent merges two types of nitrile group-containing highly saturated copolymer rubber with different Mooney viscosity ranges (5-30 and 31-70) in specific proportions. This combination allows the high viscosity component to provide tensile stress while the low viscosity component maintains workability, achieving both strength and ease of operation.
Data Source
AI summary
A nitrile group-containing highly saturated copolymer rubber composition containing a nitrile group-containing highly saturated copolymer rubber (A) having a Mooney viscosity [ML1+4, 100°C] of 50 to 200, a nitrile group-containing highly saturated copolymer rubber (B) having a Mooney viscosity [ML1+4, 100°C] of 5 to 45, and staple fibers (C) having an average fiber length of 0.1 to 12 mm is provided. According to the present invention, a nitrile group-containing highly saturated copolymer rubber composition which can give cross-linked rubber which is extremely high in tensile stress and is excellent in low heat buildup property and has good workability can be provided.