Expanded Beads Molded Article with Through-Holes for Shoe Sole Cushioning
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Solution Overview
Problem
Existing expanded beads molded articles lack compatibility between lightness in weight and restorability after compression release, with issues in compression strength and fusion bonding properties, particularly in the use of ethylene/α-olefin multi-block copolymers and polyethylene block copolymers.
Innovation Solution
Development of expanded beads molded articles using a block copolymer of polyethylene and ethylene/α-olefin copolymer blocks with through-holes, produced through a method involving dispersion, crosslinking with organic peroxides, impregnation with blowing agents, and expansion, achieving a voidage of 5-40% and a density of 30-150 g/L, and a flexural modulus of 10-100 MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If expanded beads molded articles are made lighter by increasing voidage, then weight is reduced, but compression strength and restorability deteriorate
Solution Approach 1:
The patent optimizes the voidage parameter to a specific range of 5-40% and controls density to 30-150 g/L, achieving a balance between lightness and compression strength. This parameter optimization allows the material to maintain sufficient structural integrity while being lightweight, resolving the contradiction between weight reduction and strength maintenance.
Solution Approach 2:
The patent uses block copolymer materials consisting of polyethylene blocks and ethylene/α-olefin copolymer blocks, creating a composite structure with both hard and soft phases. This composite material structure provides both lightness and adequate compression strength, as the hard phases provide structural support while the soft phases provide cushioning and weight reduction.
2Weight of moving object
If expanded beads molded articles are made lighter by increasing voidage, then weight is reduced, but restorability after compression deteriorates
Solution Approach 1:
The patent specifies a voidage range of 5-40% and density of 30-150 g/L to optimize the balance between lightness and restorability. By controlling these parameters, the material achieves rapid restorability while maintaining low weight, as the controlled void structure allows for efficient rebound without excessive weight.
Solution Approach 2:
The block copolymer composite structure with polyethylene and ethylene/α-olefin copolymer blocks provides both lightness and rapid restorability. The composite structure enables the material to rebound quickly after compression while maintaining low weight, resolving the contradiction between weight reduction and restorability maintenance.
3Adaptability or versatility
If ethylene/α-olefin multi-block copolymer is used to improve flexibility, then flexibility is enhanced, but compression strength and fusion bonding properties deteriorate
Solution Approach 1:
The patent employs a composite block copolymer structure combining polyethylene blocks (providing flexibility) with ethylene/α-olefin copolymer blocks (providing compression strength). This composite approach allows the material to achieve both flexibility and compression strength simultaneously, resolving the contradiction between flexibility enhancement and compression strength maintenance.
4Ease of manufacture
If expanded beads are produced through press expansion method, then manufacturing process is simplified, but in-mold molding capability and restorability are insufficient
Solution Approach 1:
The patent optimizes the voidage parameter to 5-40% and density to 30-150 g/L, which enables the material to achieve rapid restorability while remaining suitable for in-mold molding processes. This parameter optimization allows the material to maintain both manufacturability and restorability, resolving the contradiction between process simplicity and restorability maintenance.
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 enables expanded beads molded articles that balance lightness and rapid restorability after compression, with improved compression set resistance and fusion bonding properties, making them suitable for applications like shoe soles and cushioning materials.
Implementation Method 1
crosslinking the polymer particles at a temperature equal to or higher than a melting point of the block copolymer
Implementation Method 2
impregnating the polymer particles with a blowing agent; and expanding the resulting expandable polymer particles containing the blowing agent
Data Source
AI summary
The present invention relates to an in-mold expanded beads molded article of expanded beads of an olefin thermoplastic elastomer, a cushion for shoe sole, and a method of producing expanded beads provided with through-holes and composed of a block copolymer of a polyethylene block and an ethylene/α-olefin copolymer block, and with respect to the in-mold expanded beads molded article of expanded beads of an olefin thermoplastic elastomer, a voidage of the expanded beads molded article is 5 to 40%; a density of the expanded beads molded article is 30 to 150 g/L; and a flexural modulus of the olefin thermoplastic elastomer that constitutes the expanded beads molded article is 10 to 100 MPa.