Polyurethane Prepolymer Adhesive with Dispersion Triol
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Solution Overview
Problem
Existing adhesive compositions with polyurethane prepolymers lack improved mechanical properties and a phase-separated structure for flexibility at low temperatures and high viscosity at room temperature, while also requiring enhanced stability and shelf life.
Innovation Solution
A polyurethane prepolymer is developed comprising polyisocyanates, isocyanate-reactive compounds, and a dispersion triol with specific molecular weight and hydroxyl number ranges, along with a catalyst for isocyanate-water reaction, to achieve a free isocyanate content of 2.2-15% and a viscosity suitable for bonding substrates effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyurethane prepolymer compositions are used, then basic adhesive function is achieved, but mechanical properties and phase-separated structure for flexibility at low temperature are insufficient
Solution Approach 1:
The patent uses a composite polyol system combining HSCPP (high solid copolymer polyol) with a second polyol component. The HSCPP provides mechanical strength and rigidity through its high solids content (40-70 wt%) and glassy organic particles, while the second polyol component contributes flexibility and low-temperature performance. This composite approach allows simultaneous achievement of both strength and low-temperature flexibility that single polyol systems cannot provide.
Solution Approach 2:
The patent creates a phase-separated structure where different polyol components segregate into distinct phases within the adhesive matrix. The HSCPP-rich phases provide local regions of high strength and rigidity, while the second polyol-rich phases provide local regions of flexibility and low-temperature performance. This local differentiation of properties throughout the material enables simultaneous optimization of both mechanical strength and low-temperature flexibility.
2Productivity
If high solids copolymer polyol is used to increase capacity and reduce waste, then productivity improves, but adhesive composition complexity increases
Solution Approach 1:
The patent modifies the molecular weight and hydroxyl number parameters of the polyol components to optimize performance. Specifically, the HSCPP has a molecular weight of 4,000-8,000 g/mol and hydroxyl number of 30-75, while the second polyol has complementary parameters. These parameter optimizations allow high solids content (improving productivity) while maintaining compatibility and controlled phase separation (managing composition complexity).
Solution Approach 2:
The patent uses HSCPP at high concentrations (40-70 wt% of total polyol content) to maximize its benefits of increased capacity and reduced waste. By applying partial action with the second polyol component (30-60 wt%), the system achieves the productivity gains from high solids content while using the smaller amount of second polyol to provide necessary flexibility and control phase separation, thereby managing overall composition complexity.
3Strength
If free isocyanate content is increased to improve bonding strength, then adhesion improves, but stability and shelf life deteriorate
Solution Approach 1:
The patent optimizes the free isocyanate content parameter to a specific range (2.2-15 wt%) that balances bonding strength and stability. This parameter optimization, combined with the specific molecular weight and hydroxyl number ranges of the polyol components, creates a formulation where sufficient reactive isocyanate groups are available for strong bonding while the overall composition remains stable during storage. The phase-separated structure also helps control reactivity and improve shelf life.
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 solution provides improved mechanical properties, flexibility at low temperatures, and high viscosity at room temperature, ensuring stable adhesion and extended shelf life of the adhesive, with enhanced bonding strength and durability.
Implementation Method 1
the prepolymer comprises the reaction product of: (A) one or more polyisocyanates; (B) one or more compounds containing on average more than one isocyanate reactive compound
Implementation Method 2
a catalyst capable of catalyzing the reaction of isocyanate moieties with water
Implementation Method 3
A dispersion triol containing from 10 to 60 percent by weight, based on the weight of the dispersion, of particles of an organic polymer
Data Source
Figure 1~2
Figure 3
AI summary
A high solid copolymer polyol adhesive composition comprising: (A) A polyurethane prepolymer comprising: (1) One or more polyisocyanates; (2) One or more compounds containing on average more than one isocyanate reactive compound; (3) A dispersion triol containing from 10 to 60 percent by weight, based on the weight of the dispersion, of particles of an organic polymer which is nonreactive with the isocyanate reactive compounds and the polyisocyanates having a particle size of less than 5 microns; wherein the prepolymer has a free isocyanate content of greater than 2.2 to 15 percent; and (B) A catalyst capable of catalyzing the reaction of isocyanate moieties with water.