Resin Composition for Foams with Low Specific Gravity
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Solution Overview
Problem
Existing resin compositions for foams, particularly used in shoe soles, face challenges in achieving low specific gravity, low compression set, and excellent vibration-damping properties at room temperature to high temperatures, while maintaining mechanical strength and tear resistance.
Innovation Solution
A resin composition comprising an ethylene/α-olefin copolymer, a hydrogenated copolymer derived from a conjugated diene and vinyl aromatic compound, and optionally a natural resin or ethylene/polar monomer copolymer, with a blowing agent and crosslinking agents, which is processed to create foams with controlled properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinked foam of ethylene/vinyl acetate copolymer is used, then mechanical strength is maintained, but specific gravity increases and compression set increases
Solution Approach 1:
The invention changes the chemical composition parameters by replacing ethylene/vinyl acetate copolymer with ethylene/α-olefin copolymer having specific density (0.89-0.92 g/cm³) and melt flow rate (0.5-5 g/10min), combined with hydrogenated copolymer (B) and natural resin (C), achieving lower specific gravity while maintaining mechanical strength through optimized compositional parameters
Solution Approach 2:
The invention uses a composite material system consisting of ethylene/α-olefin copolymer (A), hydrogenated copolymer (B) obtained by hydrogenating copolymer of conjugated diene and vinyl aromatic compound, and natural resin (C) such as rosin-based or terpene-based resin, creating a multi-component foam that achieves both low weight and high strength
2Strength
If crosslinked foam of ethylene/vinyl acetate copolymer is used, then mechanical strength is maintained, but compression set increases
Solution Approach 1:
The invention optimizes compositional parameters by specifying ethylene/α-olefin copolymer (A) with density 0.89-0.92 g/cm³ and melt flow rate 0.5-5 g/10min, combined with hydrogenated copolymer (B) at 5-50 parts by weight and natural resin (C) at 1-50 parts by weight based on 100 parts of (A), achieving low compression set while maintaining mechanical strength
Solution Approach 2:
The invention incorporates natural resin (C) such as rosin-based or terpene-based resin as a cost-effective component that improves compression set resistance without requiring expensive alternative materials, providing economical solution with enhanced performance
3Ease of operation
If foam without crosslinking reaction is used, then flexibility is improved, but vibration-damping properties deteriorate at body temperature
Solution Approach 1:
The invention changes the glass transition temperature parameter by selecting hydrogenated copolymer (B) with Tg between -50°C and 0°C, ensuring the foam maintains flexibility at body temperature while the crosslinking structure provides vibration-damping properties in the desired temperature range
4Ease of operation
If foam without crosslinking reaction is used, then flexibility is improved, but mechanical strength deteriorates
Solution Approach 1:
The invention creates a composite foam system where ethylene/α-olefin copolymer (A) provides flexibility, hydrogenated copolymer (B) provides structural integrity through crosslinking, and natural resin (C) enhances mechanical properties, achieving both flexibility and mechanical strength simultaneously
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 foams with low specific gravity, low compression set, and enhanced tensile and tear strength, along with excellent vibration-damping properties across a wide temperature range, suitable for applications in footwear and other materials.
Implementation Method 1
molecular chains are bonded by the crosslinking reaction of the resins to make it possible to attain lightening due to foaming with inhibiting lowering of mechanical strength
Implementation Method 2
a technique of using crosslinked foams has been widely used for building interior and exterior materials
Implementation Method 3
have mechanical strength to endure severe use conditions and vibration-damping properties to absorb impact in the landing
Data Source
AI summary
The present invention provides a resin composition capable of providing foams (non-crosslinked and crosslinked foams) which have low specific gravity and low compression set (CS) and are excellent in tensile strength properties, tear strength properties and vibration-damping properties at room temperature to high temperatures, and a foam of the resin composition. The resin composition for foams of the present invention comprises 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A) and 5 to 95 parts by weight of a hydrogenated copolymer (B) obtained by hydrogenating a copolymer comprising a conjugated diene and a vinyl aromatic compound, and is characterized in that the hydrogenated copolymer (B) does not have a glass transition point of not higher than −10° C. when measured at a frequency of 1 Hz in accordance with JIS-K7198.