Nitrile Rubber Composition for Balanced Heat and Cold Resistance
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Solution Overview
Problem
Highly-saturated nitrile group-containing copolymer rubber faces challenges in achieving a balance of mechanical strength, heat aging resistance, oil resistance, cold resistance, and ozone resistance, with existing solutions either compromising on one or more of these properties.
Innovation Solution
A nitrile group-containing copolymer rubber composition with specific ratios of α,β-ethylenically unsaturated nitrile unit, α,β-ethylenically unsaturated carboxylic acid ester unit, conjugated diene unit, and saturated conjugated diene unit, vulcanized with an organic peroxide, to achieve a balanced vulcanizate with improved mechanical strength, heat aging resistance, oil resistance, cold resistance, and ozone resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of nitrile group is reduced to improve cold resistance, then cold resistance is improved, but heat resistance and ozone resistance deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters by introducing saturated conjugated diene units with specific content ratios (c/(c+d) ≤ 0.08) and controlling the product x·A ≤ 1.5, where x is the ratio of conjugated diene unit to total diene units and A is the content ratio of α,β-ethylenically unsaturated nitrile unit. This parameter optimization allows achieving both cold resistance and heat resistance simultaneously
Solution Approach 2:
The invention creates a composite polymer structure combining multiple unit types (α,β-ethylenically unsaturated nitrile unit, α,β-ethylenically unsaturated carboxylic acid ester unit, conjugated diene unit, and saturated conjugated diene unit) in specific proportions. This composite structure enables the material to exhibit both cold resistance from the unsaturated units and heat resistance from the saturated units
2Reliability
If the degree of saturation is increased to improve heat resistance, then heat resistance is improved, but cold resistance deteriorates
Solution Approach 1:
The invention optimizes the saturation level by controlling the content ratio of saturated conjugated diene unit to total diene units (d/(c+d)) to be within 0.92 to 0.98, and by limiting the product x·A ≤ 1.5. This controlled saturation approach maintains enough unsaturated bonds for cold resistance while providing sufficient saturated bonds for heat resistance
3Reliability
If conventional highly-saturated nitrile group-containing copolymer rubber is used, then heat resistance and oil resistance are improved, but cold resistance and mechanical strength are insufficient
Solution Approach 1:
The invention develops a composite polymer structure incorporating four different unit types in specific ratios: α,β-ethylenically unsaturated nitrile unit (10-40 wt%), α,β-ethylenically unsaturated carboxylic acid ester unit (10-60 wt%), conjugated diene unit (20-70 wt% total), and saturated conjugated diene unit (20-70 wt% total). This multi-component composite structure provides both heat resistance from saturated units and cold resistance from unsaturated units, while also improving mechanical strength
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 solution results in a vulcanizate that is highly balanced in mechanical strength, heat aging resistance, oil resistance, cold resistance, and ozone resistance, suitable for various applications including vibration insulators and automobile parts.
Implementation Method 1
vulcanizing this nitrile group-containing copolymer rubber with a vulcanizing agent (preferably an organic peroxide)
Data Source
AI summary
A nitrile group-containing copolymer rubber comprising 10 to 40 wt % of α,β-ethylenically unsaturated nitrile unit (a), 10 to 60 wt % of α,β-ethylenically unsaturated carboxylic acid ester unit (b), and 20 to 70 wt % in total of conjugated diene unit (c) and saturated conjugated diene unit (d), wherein a content ratio “x” of a conjugated diene unit (c) based on the total content of said conjugated diene unit (c) and said saturated conjugated diene unit (d) is 0.08 or smaller, and “x·A” defined as a product of said ratio “x” and a content ratio “A” (%) of said α,β-ethylenically unsaturated nitrile unit (a) is 1.5 or smaller. According to the present invention, a nitrile group-containing copolymer rubber capable to provide a rubber vulcanizate highly balanced in mechanical strength, heat aging resistance, oil resistance, cold resistance and ozone resistance, and a vulcanizable rubber composition using the rubber can be provided.