Polyvinyl Acetate Viscosity Modification in Polyisocyanate Components
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Solution Overview
Problem
Current two-component curable polyurethane systems face challenges in effectively increasing the viscosity of the polyisocyanate component, which affects the overall adhesive properties and application methods, with existing methods like pre-polymer production raising regulatory concerns and introducing repeatability issues, and silica-based thixotropes causing de-gassing issues.
Innovation Solution
Incorporating polyvinyl acetate homopolymers into the polyisocyanate component, which forms a stable, homogeneous mixture that significantly increases viscosity without introducing shear thinning characteristics, allowing for the creation of two-component systems with improved adhesion and self-leveling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If pre-polymer production is used to increase viscosity of the polyisocyanate component, then viscosity is increased, but regulatory concerns and repeatability issues are introduced
Solution Approach 1:
The patent changes the chemical composition parameter by incorporating polyvinyl acetate polymer into the polyisocyanate component, achieving viscosity increase through compositional modification rather than pre-polymer formation. This alternative parameter change approach avoids the regulatory and repeatability issues associated with pre-polymer production while effectively increasing viscosity to the desired range.
2Force
If silica is incorporated into the polyisocyanate component to increase viscosity, then viscosity is increased, but shear thinning properties and de-gassing issues are introduced
Solution Approach 1:
The patent replaces silica-based thixotropic agents with polyvinyl acetate polymer, which provides viscosity increase without the harmful de-gassing effects. The polyvinyl acetate acts as a effective viscosity modifier that does not introduce the same harmful side effects as silica, achieving the desired rheological properties without compromising system performance.
3Force
If polyvinyl acetate homopolymer is added to the polyisocyanate component, then viscosity increases significantly, but the mixture stability must be maintained
Solution Approach 1:
The patent optimizes the concentration parameter of polyvinyl acetate homopolymer in the polyisocyanate component, achieving significant viscosity increase (up to 6000%) while maintaining mixture stability. By carefully controlling the amount of polyvinyl acetate added and ensuring proper mixing, the system achieves both high viscosity and stable homogeneous mixture, suitable for potting and adhesive applications.
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 use of polyvinyl acetate homopolymers increases the viscosity of the polyisocyanate component by up to 6000%, maintaining Newtonian viscosity and enhancing the adhesion and application properties of the two-component systems, particularly suitable for potting and adhesive applications.
Implementation Method 1
Incorporating polyvinyl acetate homopolymers into the polyisocyanate component, which forms a stable, homogeneous mixture that significantly increases viscosity without introducing shear thinning characteristics
Data Source
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AI summary
Disclosed is a two-component curable polymeric system having increased viscosity. One component contains a homogeneous blend of a polyisocyanate and a homopolymer or copolymer of vinyl acetate. This component has a higher viscosity than the polyisocyanate alone, thereby increasing the viscosity of the two-component curable system. The other component of the two-component curable system is a composition containing an isocyanate reactive component. The polyisocyanate and the isocyanate reactive component react together ("cure") to form a polymer. Typically, but not always, the isocyanate reactive component is a polyol or polyamine that is capable of reacting with the polyisocyanate, thereby forming a polyurethane (polyol) or polyurea (polyamine).