Thermoplastic Polyurethane Chain Extender Mixture for Ski Boots
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Solution Overview
Problem
Current thermoplastic polyurethanes for ski boots lack the combination of high transparency, low-temperature flexibility, and mechanical strength, particularly at large wall thicknesses, which limits design options and performance.
Innovation Solution
A process involving a chain extender mixture of a main chain extender and co-chain extenders with specific molecular weights, combined with isocyanates, to produce thermoplastic polyurethane with a high rigid phase fraction, enabling high transparency and mechanical strength through injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thermoplastic polyurethanes are used for ski boots, then processing is simplified, but transparency and low-temperature mechanical strength are insufficient
Solution Approach 1:
The patent changes the molecular weight parameters of the chain extenders used in TPU synthesis. Specifically, it employs a mixture of chain extenders with molecular weights of 50-499 g/mol (preferably 70-300 g/mol), which optimizes the rigid phase fraction and delivers superior low-temperature impact strength while maintaining processability.
Solution Approach 2:
The patent uses a composite chain extender system comprising multiple components: a main chain extender (c1) and co-chain extenders (c2), where the co-chain extenders have molecular weights of 500-10000 g/mol. This composite approach creates a synergistic effect that enhances both mechanical properties and transparency.
2Strength
If chain extenders with low molecular weight are used to increase rigid phase fraction, then transparency improves, but mechanical strength at large wall thicknesses deteriorates
Solution Approach 1:
The patent segments the chain extender functionality into two distinct components: main chain extenders (c1) with molecular weights of 50-499 g/mol that provide transparency and rigid phase fraction, and co-chain extenders (c2) with molecular weights of 500-10000 g/mol that enhance mechanical strength. This segmentation allows each component to optimize for its specific function.
Solution Approach 2:
The patent applies local quality by assigning different molecular weight ranges to different chain extender components based on their specific roles. The main chain extenders (lower molecular weight) are optimized for transparency and rigid phase formation, while co-chain extenders (higher molecular weight) are optimized for mechanical strength enhancement.
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 thermoplastic polyurethane exhibits a large processing window, high transparency, and enhanced low-temperature properties, including high notched impact strength, suitable for complex ski boot designs and performance.
Implementation Method 1
a process for the preparation of thermoplastic polyurethane by reacting (a) isocyanates with (b) compounds reactive toward isocyanates and having a molecular weight (Mw) of from 500 to 10 000 g/mol and (c) chain extenders having a molecular weight of from 50 to 499 g/mol
Data Source
AI summary
A process for the preparation of thermoplastic polyurethane by reacting (a) isocyanates with (b) compounds reactive toward isocyanates and having a molecular weight (Mw) of from 500 to 10 000 g/mol and (c) chain extenders having a molecular weight of from 50 to 499 g/mol, if appropriate in the presence of (d) catalysts and/or (e) conventional additives, wherein the chain extender mixture consisting of a main chain extender (c1) and one or more co-chain extenders (c2) is used and the thermoplastic polyurethane prepared has a rigid phase fraction of greater than 0.40, the rigid phase fraction being defined by the following formula:rigidphasefraction={∑x=1k[(mKVx/MKVx)*MIso+mKVx]}/mgeswith the following meanings:MKVx: molar mass of the chain extender x in g/molmKVx: mass of the chain extender x in gMIso: molar mass of the isocyanate used in g/molmges: total mass of all starting materials in gk: number of chain extenders.