Silane-Terminated Polymer Adhesives for Safe High-Strength Bonding
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Solution Overview
Problem
Existing adhesives with high tensile shear strength often require toxic tin catalysts and have high viscosity, making them costly and difficult to apply, while isocyanate-based adhesives pose health risks due to volatile monomeric isocyanates.
Innovation Solution
Multicomponent crosslinkable compositions based on organyloxysilane-terminated polymers and silicone resins, free from toxic catalysts and isocyanates, which cure through a condensation reaction with atmospheric moisture, achieving high tensile shear strength without the need for aggressive catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If isocyanate-crosslinking adhesives are used to achieve high tensile shear strength, then adhesive strength is improved, but health safety deteriorates due to volatile monomeric isocyanates
Solution Approach 1:
The patent changes the chemical composition parameters by replacing isocyanate groups with alkoxysilane-functional prepolymers. This substitution maintains the crosslinking capability and adhesive strength while eliminating the harmful volatile monomeric isocyanates, thus resolving the contradiction between strength and health safety
Solution Approach 2:
The patent uses prepolymers with reactive alkoxysilyl groups that cure upon contact with atmospheric moisture. These prepolymers are designed to be stable during storage but reactive during application, eliminating the need for toxic catalysts and providing a safe, disposable adhesive system that achieves high strength without health risks
2Object-affected harmful factors
If silane-functional prepolymers are used for crosslinking, then health safety is improved, but reactivity with moisture deteriorates, requiring aggressive catalysis
Solution Approach 1:
The patent modifies the chemical parameters of the silane prepolymers by incorporating specific functional groups that enhance moisture reactivity. This allows the prepolymers to cure effectively upon contact with atmospheric moisture without requiring toxic tin catalysts, thus maintaining both health safety and adequate reactivity
Solution Approach 2:
The prepolymers are designed to be self-curing upon contact with atmospheric moisture, eliminating the need for external catalysts. The molecular structure is engineered to naturally react with moisture at appropriate rates, providing a self-service system that is both safe and reactive without aggressive catalysis
3Strength
If high concentrations of silane-crosslinking groups are used to achieve high tensile shear strength, then adhesive strength is improved, but viscosity increases, making application difficult
Solution Approach 1:
The patent creates a composite system combining prepolymers with reactive alkoxysilyl groups and silicone resins. This composite formulation achieves high tensile shear strength through crosslinking while the resin component maintains appropriate viscosity for easy application, resolving the contradiction between strength and ease of operation
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 compositions exhibit excellent tensile shear strength, are free from toxic catalysts, and have improved processing qualities, making them suitable for various applications without the health risks associated with isocyanate-based adhesives.
Implementation Method 1
alkoxysilane-functional prepolymers initially undergo hydrolysis on contact with atmospheric moisture
Implementation Method 2
then cure through a condensation reaction
Data Source
AI summary
Multicomponent crosslinkable compositions based on organyloxysilane-terminated polymers free of toxicologically objectionable catalysts and isocyanates exhibiting good tensile shear strength are useful for adhesive bonding and sealing of substrates.