Silyl-Terminated Prepolymer Sealant for Waterproofing
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Solution Overview
Problem
Current sealants and coatings used in construction are prone to blistering, have poor water resistance, and mechanical strength issues, and often contain harmful solvents and residual diisocyanates, making them unsuitable for waterproofing applications, especially on traffic-bearing surfaces.
Innovation Solution
A silyl-terminated prepolymer is developed through a Michael addition reaction between a polyamine or polythiol and an electrophile with an α,β-unsaturated carbonyl group, forming a one-component, moisture-curable composition with reduced solvent content and minimal free isocyanate monomers, which cures rapidly at room temperature and provides improved mechanical properties and hydrolysis resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acrylic dispersions in aqueous solution are used for sealants or coatings, then ease of application is improved, but water resistance and mechanical strength deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by using polyurethane resins instead of acrylic dispersions, and controls the solvent content within specific ranges (0-10% by weight) to achieve both ease of application and water resistance. The resin structure and composition are optimized to provide the required performance balance.
Solution Approach 2:
The patent creates a composite composition combining polyurethane resin with specific additives including adhesion promoters, plasticizers, and curing agents. This composite formulation provides the synergistic effect of ease of application from the resin system while achieving water resistance through the composite structure and controlled composition.
2Ease of operation
If polyurethane resins with significant amounts of solvents and plasticizers are used, then ease of application is improved, but mechanical strength and adhesion deteriorate
Solution Approach 1:
The patent optimizes the solvent content parameter to 0-10% by weight and plasticizer content to 5-20% by weight, finding the optimal balance between application ease and mechanical strength. This parameter control prevents excessive softening while maintaining workability.
Solution Approach 2:
The patent uses inert plasticizers that mimic the application benefits of traditional plasticizers without the harmful effects. These plasticizers provide ease of application while maintaining mechanical strength by not interfering with the polymer network formation.
3Strength
If two-component compositions are used for polyurethane sealants, then mechanical strength is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent merges the polyurethane resin, curing agent, and other components into a single one-component system that cures by moisture from the air. This eliminates the need for separate mixing and application of multiple components while maintaining the mechanical strength through the crosslinked polymer structure formed during moisture curing.
Solution Approach 2:
The patent employs a moisture-curing mechanism where the composition uses ambient moisture to trigger the curing reaction. This self-curing capability eliminates the need for external catalysts or second components, simplifying the application process while achieving the desired mechanical strength through the crosslinked network formation.
4Ease of operation
If solvents are used in polyurethane compositions, then ease of application is improved, but harmful factors and environmental compliance deteriorate
Solution Approach 1:
The patent changes the solvent content parameter to a minimal range (0-10% by weight) and uses specific solvent types with lower toxicity and odor. This parameter optimization maintains application ease while significantly reducing harmful emissions and improving environmental compliance.
Solution Approach 2:
The patent uses volatile solvents that evaporate completely after application, leaving no harmful residue. These solvents provide temporary assistance during application ease but disappear afterward, eliminating long-term harmful effects and environmental concerns.
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 resulting composition exhibits excellent mechanical properties, rapid curing, and enhanced hydrolysis resistance, making it suitable for waterproofing applications on horizontal traffic-bearing surfaces without the drawbacks of traditional sealants, such as blistering and solvent-related issues.
Implementation Method 1
A silyl-terminated prepolymer is developed through a Michael addition reaction between a polyamine or polythiol and an electrophile with an α,β-unsaturated carbonyl group
Implementation Method 2
forming a one-component, moisture-curable composition with reduced solvent content and minimal free isocyanate monomers, which cures rapidly at room temperature
Data Source
AI summary
The invention relates to a silyl terminated prepolymer and to a curable composition containing this prepolymer. These compositions are used to make sealants, coatings or adhesives useful in the field of construction, public works and civil engineering.