Metallocene EPDM Copolymer for Low-Cost Foam Shape Retention
Solution Overview
Problem
Current rubber compositions, particularly EPDM, face challenges in achieving adequate foamability and shape-retaining properties while reducing the usage of expensive nonconjugated polyenes, leading to high production costs and suboptimal mechanical properties.
Innovation Solution
A rubber composition incorporating a copolymer with specific structural units derived from ethylene, α-olefins, and nonconjugated polyenes, where the copolymer is synthesized using a metallocene catalyst, optimizing the mole percentage and ratio of these components to enhance foamability and shape retention with reduced polyene usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large amounts of expensive nonconjugated polyene (e.g., ENB or VNB) are used to improve foamability and shape-retaining properties, then the foamability and shape stability are improved, but the production cost increases significantly
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific nonconjugated diene components (5-vinyl-2-norbornene and 5-ethylidene-2-norbornene) with controlled ratios. The copolymer contains 0.1-10 mass% of 5-vinyl-2-norbornene and 0.1-10 mass% of 5-ethylidene-2-norbornene, with their structural units appearing in specific ratios that optimize both foamability and cost-effectiveness, reducing reliance on expensive traditional polyenes
Solution Approach 2:
The patent creates a composite copolymer structure combining ethylene, α-olefin, and specific nonconjugated diene components. This composite approach integrates multiple functional units: ethylene for base polymer structure, α-olefin for copolymerization and physical properties, and nonconjugated dienes for crosslinking and foam stability, achieving superior performance at lower cost
2Reliability
If the high-molecular weight component of EPDM is increased to improve gas-retaining property and shape stability, then the foamability is improved, but the processing difficulty and production cost increase
Solution Approach 1:
The patent optimizes molecular weight parameters by controlling the copolymer's viscosity (Mooney viscosity ML(1+4) at 100°C: 20-100) and molecular weight distribution. This balanced approach ensures adequate gas-retaining property for foaming while maintaining processability during extrusion and molding operations
Solution Approach 2:
The patent introduces dynamic control of molecular structure through copolymerization with α-olefins (propylene, 1-butene, 1-hexene, or 1-octene) containing 3-20 carbon atoms. The α-olefin content (5-50 mol%) dynamically adjusts the polymer's flexibility, gas-retaining capability, and processability, achieving optimal balance between foam quality and manufacturing ease
3Ease of manufacture
If the usage of expensive nonconjugated polyene is reduced to lower production cost, then the production cost decreases, but the foamability and mechanical strength deteriorate
Solution Approach 1:
The patent substitutes expensive traditional nonconjugated polyenes (ENB, VNB) with more cost-effective nonconjugated diene components. By using 5-vinyl-2-norbornene and 5-ethylidene-2-norbornene at optimized levels (total 0.2-20 mass%), the formulation achieves required foamability and mechanical strength at lower material cost
Solution Approach 2:
The patent creates a synergistic composite system where ethylene provides structural backbone, α-olefins enhance flexibility and processability, and nonconjugated dienes contribute crosslinking sites for mechanical strength. This composite approach distributes functional requirements across multiple components, maintaining performance while reducing dependence on any single expensive ingredient
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 a rubber composition with improved foamability, shape-retaining properties, and reduced production costs by utilizing a specific copolymer structure that balances vulcanization and mechanical strength, suitable for applications like automobile exterior materials.
Implementation Method 1
a copolymer (A) including structural units derived from ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms, a nonconjugated polyene (C-1), in which among carbon-carbon double bonds, only one carbon-carbon double bond polymerizable with a metallocene catalyst is present in one molecule, and a nonconjugated polyene (C-2), in which among the carbon-carbon double bonds, two carbon-carbon double bonds polymerizable with the metallocene catalyst are present in one molecule, and being synthesized through the use of the metallocene catalyst
Data Source
AI summary
The present invention provides a rubber composition having adequate foamability, uses thereof, a copolymer contained in the rubber composition, a rubber composition capable of providing a cross-linked foam, which has a low specific gravity and an excellent shape-retaining property even when the usage of a nonconjugated polyene is reduced, and a cross-linked rubber and a cross-linked foam, which are produced from the rubber composition. A copolymer (A) according to the present invention is a copolymer including structural units derived from ethylene [A], an α-olefin [B], a nonconjugated polyene [C-1], in which one carbon-carbon double bond (C═C) polymerizable with a metallocene catalyst is present in one molecule, and a nonconjugated polyene [C-2], in which two bonds of C═C polymerizable with the metallocene catalyst are present in one molecule, and being synthesized with the metallocene catalyst, wherein (1) the units derived from the component [B] constitute 10 to 50 percent by mole, (2) the total of the units derived from the component [C-1] and the units derived from the component [C-2] is 1.0 to 6.0 percent by mole, (3) the molar ratio of the units derived from the component [C-1] to the units derived from the component [C-2] is 75/25 to 99.5/0.5, (4) [ML (1+4) 100° C.] is 10 to 200, and (5) 50>activation energy of fluidization (kJ/mol)>35 is satisfied.