Thermoplastic Polyurethane Films with Mixed Polyol for High Moisture Vapor Transmission
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Solution Overview
Problem
Existing thermoplastic polyurethane compositions do not achieve high enough moisture vapor transmission rates, particularly when based on poly(ethylene oxide) polymers, limiting their suitability for breathable applications such as films and garments.
Innovation Solution
A thermoplastic polyurethane composition is developed using a mixed polyol component comprising a combination of poly(ethylene oxide) polyols and copolymer polyols, where the copolymer polyol is a copolymer of ethylene oxide and C3 to C15 alkylene oxides, specifically contributing from 3 to 30 weight percent to the mixed polyol component, enhancing moisture vapor transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoplastic polyurethane is made from poly(ethylene oxide) polyols, then moisture vapor transmission rate is improved, but the MVT rate is still not high enough for breathable applications
Solution Approach 1:
The patent uses a mixed polyol component comprising poly(ethylene oxide) polyol and copolymer polyol (containing C3-C15 alkylene oxide units) to create a composite polymer structure. This composite approach combines the high MVT properties of PEO-based segments with the breathability enhancement from copolymer segments, achieving synergistic improvement in moisture vapor transmission that neither component achieves alone.
2Reliability
If copolymer polyol is added to enhance moisture vapor transmission, then MVT rate increases, but polyol component composition becomes more complex
Solution Approach 1:
The patent optimizes the composition parameters of the mixed polyol component, specifying that it comprises from about 70 to about 97 weight percent poly(ethylene oxide) polyol and from about 3 to about 30 weight percent copolymer polyol. By carefully controlling these parameter ranges, the invention achieves high MVT rates while maintaining manageable composition complexity and processing characteristics.
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 polyurethane films exhibit significantly higher moisture vapor transmission rates, allowing for breathable and water-permeable yet water-impermeable materials, suitable for applications like roofing membranes, house wraps, and apparel, with increased MVT rates up to several hundred percent compared to similar compositions without the mixed polyol component.
Implementation Method 1
The copolymer polyol is a copolymer of ethylene oxide and a C3 to C15 alkylene oxide... The resulting polyurethane films exhibit significantly higher moisture vapor transmission rates
Data Source
AI summary
The present invention relates generally to polyurethane compositions; and more preferably to thermoplastic polyurethane compositions. In one embodiment, the polyurethane compositions of the present invention have high moisture vapor transmission rates and are suitable for film applications (e.g., breathable films). In one embodiment, the polyurethane compositions of the present invention are prepared from the reaction of a mixed polyol component, a polyisocyanate component, a chain extender, and optionally at least one suitable catalyst, wherein the mixed polyol component is formed by a combination of one or more poly(ethylene oxide) polyols and one or more copolymer polyols, where the resulting mixed polyol component comprises from about 3 to about 30 weight percent of a copolymer polyol and about 70 to 97 weight percent of poly(ethylene oxide) polyol.