Isocyanate-Terminated Prepolymer Binder for Low-Viscosity Composite Articles
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Solution Overview
Problem
Existing polyurethane binders face challenges such as sensitivity to humidity, solvent presence, and catalyst limitations, leading to processing difficulties and reduced mechanical performance in composite production, particularly with prepolymers based on diphenylmethane diisocyanate which crystallize at low temperatures and have high viscosity, and the use of solvents causing dimensional instability.
Innovation Solution
A urethane-modified isocyanate binder system derived from a polyol with a tertiary nitrogen initiator, which reacts with a stoichiometric excess of aliphatic or aromatic polyisocyanate, reducing the need for catalysts and improving cure times, workability, and mechanical performance by forming a non-foamed polyurethane matrix with particulate matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prepolymers based on diphenylmethane diisocyanate are used as binder, then the composite article can be manufactured with standard polyurethane binding properties, but the prepolymer crystallizes at temperatures around 0°C or slightly above, causing storage and use constraints in cold conditions
Solution Approach 1:
The patent changes the chemical parameters of the isocyanate component by using alternative isocyanates (toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, or mixtures thereof) instead of diphenylmethane diisocyanate. This parameter change modifies the prepolymer's crystallization behavior and viscosity characteristics, enabling reliable storage and application across a broader temperature range while maintaining polyurethane binding functionality.
2Reliability
If prepolymers based on diphenylmethane diisocyanate with triisocyanates and tetraisocyanates are used to reduce crystallization tendency, then the composite article can maintain stability at low temperatures, but the viscosity at room temperature becomes so high that processing becomes difficult without adding solvents or thinners
Solution Approach 1:
The patent changes the isocyanate component parameters by selecting specific alternative isocyanates (toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate) that provide an optimal balance between crystallization resistance and viscosity. This parameter optimization enables the prepolymer to maintain low crystallization tendency while keeping room temperature viscosity at manageable levels for easy processing without requiring solvent addition.
3Ease of manufacture
If solvents or thinners are added to reduce viscosity for easier processing, then the composite article can be manufactured with improved processability, but certain particulate matter may swell due to solvent absorption and be released during curing, causing dimensional instability
Solution Approach 1:
The patent changes the chemical composition parameters of the isocyanate component to achieve optimal viscosity without requiring solvent addition. By selecting specific isocyanates and controlling the NCO index (105-130), the prepolymer attains suitable processing viscosity inherently, eliminating the need for solvents and thereby preventing particulate matter swelling and dimensional instability during curing.
4Device complexity
If atmospheric humidity is used to control the curing reaction of polyisocyanate with polyhydroxyl compound, then the composite article can be manufactured with one-component binder simplicity, but the proportions of reactions cannot easily be controlled, affecting processing and end properties
Solution Approach 1:
The patent changes the reactivity parameters of the binder system by using prepolymers with controlled NCO index (105-130) derived from alternative isocyanates. This parameter control provides inherently better reactivity and curing characteristics, enabling more precise control of the curing reaction proportions while maintaining the simplicity of one-component binder application. The modified prepolymer structure responds more predictably to atmospheric moisture, improving both processing and end properties.
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
This solution enhances the reaction profile, reducing waiting times and sensitivity to humidity, allowing for faster processing and broader application accessibility while minimizing solvent use and foam formation, resulting in improved composite articles like sports surfaces and flooring.
Implementation Method 1
mixing a polyisocyanate with a polyhydroxyl compound and compound simultaneously or subsequently with the particulate matter
Implementation Method 2
one-component polyurethane binders which are hardened only by their reaction with the atmospheric moisture
Data Source
AI summary
The present invention relates to a composite article obtained from binding or adhesion of particulate matter with a polyurethane binder which is derived from a urethane-modified isocyanate obtained by reaction of an isocyanate with a polyether polyol based on an initiator containing a tertiary nitrogen atom. Such composite articles can be, for example, recreational matting or tiles, sports or running tracks, or flooring, or laminates.