Sealing Rubber Composition for Low Compression Set and Aging Resistance
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Solution Overview
Problem
Existing ethylene propylene rubber products face challenges in achieving simultaneous improvement of aging resistance, mechanical strength, and compression set resistance, particularly due to difficulties in crosslinking and high material costs.
Innovation Solution
A rubber composition incorporating branched polyethylene with a degree of branching of not less than 50 branches/1000 carbon atoms, combined with EPM and EPDM, and a crosslinking system, to enhance crosslinking properties and reduce compression set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peroxide crosslinking system is used to improve aging resistance and compression set resistance, then mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite rubber matrix consisting of EPM (ethylene propylene monomer) and EPDM (ethylene-propylene-diene monomer) in specific proportions (EPM: 30-70 parts, EPDM: 70-30 parts). This composite structure combines the saturated molecular chain of EPM which provides excellent aging resistance with the crosslinking capability of EPDM, achieving both high aging resistance and mechanical strength simultaneously.
Solution Approach 2:
The patent optimizes the molecular structure parameters by controlling the propylene content in EPM to be 55-65% and the ethylene content in EPDM to be 45-55%. These parameter adjustments ensure the rubber has appropriate saturation degree for aging resistance while maintaining sufficient reactivity for crosslinking, thereby improving both aging resistance and mechanical strength.
2Reliability
If EPM is used to improve aging resistance, then mechanical strength deteriorates
Solution Approach 1:
The patent merges EPM and EPDM in a specific ratio to create a composite rubber matrix. EPM provides the saturated molecular chain structure for excellent aging resistance, while EPDM contributes the diene monomer units that enable effective crosslinking. This merging allows the material to simultaneously achieve high aging resistance from EPM and adequate mechanical strength from EPDM's crosslinking capability.
Solution Approach 2:
The patent creates local quality differentiation within the rubber matrix by having EPM regions providing saturation and aging resistance, while EPDM regions provide crosslinking sites. The specific proportion (30-70 parts EPM and 70-30 parts EPDM) ensures that there are sufficient crosslinking sites distributed throughout the saturated matrix, achieving both properties at different locations within the material structure.
3Reliability
If degree of branching is increased to improve aging resistance, then processability deteriorates
Solution Approach 1:
The patent optimizes the degree of branching parameter by controlling the propylene content in EPM to be 55-65% and the ethylene content in EPDM to be 45-55%. This parameter optimization achieves a balance where the molecular chain has sufficient saturation for aging resistance but not excessive branching that would hinder processing. The controlled branching degree ensures both aging resistance and processability are maintained.
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 achieves excellent aging resistance, improved mechanical properties, and better crosslinking efficiency, resulting in a sealing element with enhanced compression set resistance and reduced production costs.
Implementation Method 1
Compared with a sulfur vulcanization system, rubber products obtained by a peroxide crosslinking system have better aging resistance and lower compression set
Data Source
AI summary
The invention discloses a rubber composition and a method for processing the rubber composition, and a sealing element using the rubber composition and a production method thereof. The rubber composition comprises, in parts by weight, 100 parts of a rubber matrix, 2-20 parts of a cross-linking system, 60-300 parts of a reinforcing filler, 20-170 parts of a plasticizer and 3-25 parts of a metal oxide, wherein, the rubber matrix comprises a branched polyethylene with a content represented as A, in which 0<A≤100 parts, and both an EPM rubber and an EPDM rubber with a total content represented as B, in which 0≤B<100 parts. The invention provides a sealing element with good compression set resistance.