Crosslinked Nitrile Rubber Composition for Low Compression Set
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Solution Overview
Problem
Existing crosslinkable rubber compositions fail to achieve a balance between mechanical strength and low compression set, particularly in applications where space portions are compressed, and they also lack sufficient heat aging resistance.
Innovation Solution
A crosslinkable rubber composition comprising specific nitrile rubber, aromatic secondary amine-based anti-aging agents, and polyamine-based crosslinking agents, along with optional additives like polyoxyalkylene alkyl ether phosphate ester, to produce cross-linked rubbers with improved tensile strength, heat resistance, and significantly reduced compression set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional crosslinkable rubber compositions are used to improve mechanical strength, then tensile strength and tensile stress are improved, but compression set increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the iodine value (120 or less) and carboxyl group content (0.01 to 0.1 ephr) of the nitrile rubber, and by optimizing the amounts of crosslinking agents and accelerators. These parameter optimizations enable the rubber to achieve both high tensile strength and low compression set by adjusting the chemical composition and crosslinking density within specific ranges.
Solution Approach 2:
The patent uses composite materials by combining nitrile rubber with specific crosslinking agents (polyamine-based or polyhydric alcohol-based), accelerators (basic or neutral), and anti-aging agents (aromatic secondary amine-based). This composite formulation creates a synergistic effect where each component contributes to achieving both improved mechanical strength and reduced compression set simultaneously.
2Strength
If crosslinking is increased to improve mechanical strength, then tensile strength is improved, but heat aging resistance deteriorates
Solution Approach 1:
The patent controls the crosslinking degree through precise parameter specifications: iodine value of 120 or less, carboxyl group content of 0.01 to 0.1 ephr, and specific amounts of crosslinking agents (0.1 to 20 parts by weight). These parameters ensure sufficient crosslinking for mechanical strength while preventing excessive crosslinking that would harm heat aging resistance.
Solution Approach 2:
The patent introduces basic or neutral accelerators as intermediaries to control the crosslinking reaction rate. These accelerators mediate between the crosslinking agents and the rubber, enabling controlled crosslinking that achieves mechanical strength improvement without compromising heat aging resistance through uncontrolled rapid crosslinking.
3Reliability
If compression set is reduced through specific crosslinking, then compression set is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent optimizes the balance between compression set reduction and mechanical strength maintenance by controlling parameters within specific ranges: iodine value (120 or less), carboxyl group content (0.01 to 0.1 ephr), and crosslinking agent amounts (0.1 to 20 parts by weight). This parameter optimization ensures that crosslinking is sufficient for strength but not excessive, achieving both goals simultaneously.
Solution Approach 2:
The patent employs composite materials with multiple functional components: nitrile rubber providing base properties, crosslinking agents providing crosslinking capability, accelerators controlling reaction rate, and anti-aging agents preventing degradation. This composite system achieves balanced performance where compression set is reduced without sacrificing mechanical strength through the synergistic interaction of all components.
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 provides cross-linked rubbers with well-balanced mechanical properties, including tensile strength, elongation, and heat resistance, while maintaining a low compression set, making them suitable for various applications such as seals, belts, and hoses.
Implementation Method 1
a crosslinkable rubber composition comprising a nitrile group containing highly-saturated copolymer rubber including α,β-ethylenically unsaturated dicarboxylic acid monoalkyl ester units, a polyamine-based crosslinking agent and a basic crosslinking accelerator
Implementation Method 2
0.2 to 10 parts by weight of an aromatic secondary amine-based anti-aging agent (A2)
Data Source
AI summary
A crosslinkable rubber composition comprising 0.2 to 10 parts by weight of an aromatic secondary amine-based anti-aging agent and 0.5 to 20 parts by weight of a polyamine-based crosslinking agent with respect to 100 parts by weight of a nitrile rubber including an α,β-ethylenically unsaturated nitrile unit and an α,β-ethylenically unsaturated dicarboxylic acid monoester unit, and with iodine value of 120 or less. The present invention can provide a crosslinkable rubber composition, providable of a cross-linked rubber excellent in a variety of properties such as mechanical strength and small in compression set, and a cross-linked rubber obtained by cross-linking the rubber composition.