Hybrid Polyurethane Composites for Complete Curing and Long Open Time
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Solution Overview
Problem
Conventional polyurethane (PU) compositions exhibit a high content of un-reacted NCO, leading to incomplete polymerization and compromised polymer properties, which is unsuitable for composite manufacturing processes requiring long open time.
Innovation Solution
A hybrid polyurethane composition comprising an isocyanate component, an isocyanate-reactive component with a first polyol, an isocyanate reactive (meth)acrylate monomer, and an acetoacetoxy functional or acetoacetamido functional (meth)acrylate monomer, along with a free radical initiator, to achieve low un-reacted NCO content and improved polymer properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional 2k polyurethane composition is used, then fast reactivity and short open time are achieved, but incomplete polymerization and high un-reacted NCO content result, compromising polymer properties
Solution Approach 1:
The invention segments the curing process into two distinct stages: a first curing stage using isocyanate and polyol to form polyurethane bonds, and a second curing stage using free radical polymerization to complete the network formation. This segmentation allows each stage to optimize its reaction mechanism, ensuring complete polymerization while maintaining controllable reactivity.
Solution Approach 2:
The invention introduces a silane-modified polyol as an intermediary component that bridges the isocyanate curing system and the free radical polymerization system. The silane groups in this polyol react with isocyanate to form crosslinked structures, while the polyol hydroxyl groups also serve as initiators for subsequent free radical polymerization, ensuring complete consumption of NCO groups and eliminating un-reacted isocyanate.
2Duration of action of moving object
If hybrid PU system with ethylenically unsaturated monomer is used, then extended open time is achieved, but substantial un-reacted NCO remains after polymerization, negatively impacting polymer properties
Solution Approach 1:
The invention dynamically adjusts the curing process by controlling the sequence and conditions of the two-stage curing. The first stage uses isocyanate-polyol reaction at controlled temperature to extend open time, while the second stage activates free radical polymerization to complete the reaction. This dynamic control ensures both extended processability and complete polymerization.
Solution Approach 2:
The invention changes key parameters including introducing silane-modified polyol with specific hydroxyl value (20-100 mg KOH/g) and molecular weight (500-5000 g/mol), controlling the water content (0.01-5% by weight), and adjusting curing temperatures (50-150°C for first stage, 80-200°C for second stage) to ensure complete NCO consumption while maintaining extended open time.
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 composition results in significantly reduced residual NCO content and enhanced polymer properties, such as improved Heat Distortion Temperature (HDT), making it suitable for composite manufacturing processes.
Implementation Method 1
a free radical initiator C), and then reacting the isocyanate component A) with the isocyanate-reactive component B) in the presence of the free radical initiator C) to form the polyurethane resin
Implementation Method 2
an isocyanate-reactive component B) comprising B1) a first polyol; and B2) an isocyanate reactive (meth)acrylate monomer
Data Source
AI summary
A polyurethane composition, a composite material comprising a fiber reinforcement material and a polyurethane resin obtained from the polyurethane composition, and a method for preparing the polyurethane resin are provided. The polyurethane composition comprises: A) an isocyanate component; B) an isocyanate-reactive component comprising B1) a first polyol; B2) an isocyanate reactive (meth) acrylate monomer; and B3) an acetoacetoxy functional or acetoacetamido functional (meth) acrylate monomer; and C) a free radical initiator.