Hydrogenated Styrenic Diblock Copolymer Foam for Footwear Outsoles
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Solution Overview
Problem
Current footwear outsole materials, such as EVA foam, lack sufficient slip resistance and balanced mechanical properties, limiting their usage in footwear applications, while existing styrenic block copolymers have limitations in terms of commercial availability and mechanical properties when used as foams.
Innovation Solution
A crosslinkable and foamable composition comprising a hydrogenated styrenic diblock copolymer, combined with ethylene copolymers and free radical initiators, is developed, which is processed at specific temperatures to achieve superior anti-slip properties and balanced mechanical properties suitable for footwear outsoles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If EVA foam is used for footwear outsole, then light weight is achieved, but slip resistance is poor
Solution Approach 1:
The patent uses a composite material system combining SEBS (styrene-ethylene-butylene-styrene) thermoplastic elastomer with peroxide crosslinking agents and foaming agents. This creates a crosslinked foam structure that maintains the light weight advantage of EVA while achieving superior slip resistance through the SEBS-based crosslinked network, directly resolving the contradiction between weight and slip resistance
2Reliability
If SBC materials are used to make foams, then anti-slip properties are improved, but mechanical properties become unbalanced
Solution Approach 1:
The patent optimizes specific parameters of the SEBS copolymer including styrene content (15-30 wt%), butylene content (65-80 wt%), and molecular weight (50,000-200,000 g/mol). These parameter adjustments, combined with controlled peroxide crosslinking at 140-200°C, achieve a balance between anti-slip properties and mechanical strength, resolving the contradiction by fine-tuning material composition and processing conditions
3Productivity
If crosslinking and foaming are performed at high temperature, then foaming efficiency is improved, but material degradation occurs
Solution Approach 1:
The patent introduces peroxide crosslinking agents (such as dicumyl peroxide or 2,5-dimethyl-2,5-di(t-butylperoxy)hexane) as intermediaries that enable crosslinking reactions at moderate temperatures (140-200°C). These peroxides decompose to form radicals that initiate both crosslinking and foaming processes simultaneously, achieving efficient foam formation without excessive temperature that would cause material degradation
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 resulting foam exhibits excellent anti-slip performance and a balance of mechanical properties, including impact resilience, lightness, and permanent compression set, making it suitable for various applications including shoe outsoles.
Implementation Method 1
a step of injecting molding the crosslinkable and foamable composition in an injection mold for peroxide crosslinking and foaming agent decomposition at a temperature from about 150° C. to 200° C.
Implementation Method 2
peroxide crosslinking and foaming agent decomposition at a temperature from about 150° C. to 200° C.
Data Source
AI summary
A crosslinkable and foamable composition is provided, which comprises a hydrogenated styrenic diblock copolymer, a free radical initiator and a foaming agent, wherein the hydrogenated styrenic diblock copolymer comprises: a first block comprising an isoprene unit; and a second block comprising a styrene unit, wherein the hydrogenated styrenic diblock copolymer comprises 10 to 60 wt % of the styrene unit, 50 mol % or more of the isoprene unit is hydrogenated, and the hydrogenated styrenic diblock copolymer has a weight average molecular weight of 30000 to 200000. In addition, a foam obtained by crosslinking and foaming the aforesaid crosslinkable and foamable composition is also provided.