Polyurethaneurea Dispersion Coating for Stable Fiber-Matrix Adhesion
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Solution Overview
Problem
Existing aqueous polyurethaneurea dispersions for fiber sizing face issues such as partial deblocking during drying, leading to deterioration of fiber properties, and lack of optimal compatibility with matrix materials, particularly in epoxy resin-based systems, which can be unstable and non-storage-friendly.
Innovation Solution
Aqueous polyurethaneurea dispersion comprising specific components like polyisocyanate, polyol, and nonionic hydrophilizing agents, with controlled levels of carboxyl groups and neutralization, and chain termination by monofunctional compounds to enhance compatibility and mechanical properties of composite materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If blocked aqueous polyurethaneurea dispersions are used for fiber sizing, then adhesion to glass fibres is improved, but partial deblocking during drying occurs leading to deterioration of fiber properties
Solution Approach 1:
The patent removes the blocking agent component from the dispersion formulation, eliminating the deblocking issue during drying while maintaining adhesion through alternative mechanisms involving carboxyl groups and controlled neutralization
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating specific carboxyl-containing compounds (0.1-5.0 wt% relative to total solids) and controlling neutralization levels (pH 4.0-7.0), which provides stable adhesion without requiring blocked isocyanate groups
2Adaptability or versatility
If epoxy resins are used for fiber sizing to ensure compatibility with matrix material, then compatibility with epoxy matrix is improved, but storage stability deteriorates due to high reactivity of epoxy groups
Solution Approach 1:
The patent uses carboxyl-containing compounds and their neutralized forms as intermediary substances that provide both compatibility with epoxy matrix material and storage stability, avoiding the direct use of highly reactive epoxy resins in the size formulation
Solution Approach 2:
The patent replaces long-lived but reactive epoxy resins with more stable carboxyl-containing compounds that achieve the same compatibility function without the storage stability issues, effectively using a different chemical class that serves the same purpose
3Strength
If polyurethaneurea dispersions are optimized for fiber adhesion, then adhesion properties are improved, but compatibility with matrix material deteriorates
Solution Approach 1:
The patent creates a polyurethaneurea dispersion that performs multiple functions simultaneously: the carboxyl groups and controlled neutralization provide both fiber adhesion and matrix compatibility, making the single formulation universally effective for both interfaces
Solution Approach 2:
The patent employs a composite chemical structure in the polyurethaneurea dispersion incorporating carboxyl-containing compounds and neutralizing agents, creating a multi-component system that achieves both adhesion and compatibility properties that single-component systems cannot provide
Data Source
AI summary
The present invention relates to an aqueous polyurethaneurea dispersion, wherein the polyurethaneurea has specific formation components, and which is characterized in that it has a content of —COOH groups of at least 0.75% by weight, where 0% to 35% of these groups have been neutralized, and in that 5 to 50 mol % of isocyanate groups present have been reacted with a monofunctional component. The invention further relates to the use of this dispersion as coating composition, to a fiber having a cured coating and to a composite material.