Moisture-Curable Polyurethane Composition for Elastic Bonding and Sealing
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Solution Overview
Problem
Existing polymer-based sealants face challenges in achieving a balance between good mechanical properties, elastic properties, and adhesion, with potential restrictions on the use of epoxiles and the need for compositions that can adapt to significant movements without generating tension.
Innovation Solution
A moisture-curable composition comprising polyurethane P1 with at least two isocyanate groups and polyurethane P2 with a specific functional group, in a mass ratio ranging from 50:50 to 99:1, optimized through a polyaddition reaction process, incorporating polyols and polyisocyanates with a controlled NCO/OH molar ratio, and enhanced with a rheology agent and fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxiles are used as adhesion promoters in polyurethane-based sealants, then adhesion properties are improved, but the composition becomes subject to chemical classification restrictions and potential future bans
Solution Approach 1:
The patent removes epoxiles from the composition entirely and replaces them with alternative adhesion promoters such as aminosilanes or mercaptosilanes. This extraction eliminates the regulatory compliance issue while maintaining adhesion functionality through different chemical mechanisms.
Solution Approach 2:
The patent uses polyols with multiple hydroxyl groups (functionality 2-6) that can perform both as the main polymer backbone and as adhesion promoters, eliminating the need for separate epoxide-based adhesion promoters and reducing regulatory concerns.
2Adaptability or versatility
If the sealant has high elasticity and elongation to adapt to movements, then the modulus of elasticity decreases, but the mechanical strength may be reduced
Solution Approach 1:
The patent creates a composite polyurethane system combining polyols with functionality 2-3 (for elasticity) and polyols with functionality 4-6 (for strength and adhesion). This composite approach allows the sealant to achieve both high elongation (>300%) and adequate tensile strength by leveraging the complementary properties of different polyol components.
Solution Approach 2:
The patent introduces fillers and rheology agents at specific locations and concentrations within the sealant matrix to locally enhance mechanical strength without compromising the overall elasticity and elongation properties of the bulk material.
3Strength
If the NCO/OH molar ratio is increased to improve crosslinking and mechanical properties, then the composition becomes more sensitive to moisture and environmental factors during curing
Solution Approach 1:
The patent optimizes the NCO/OH molar ratio to a specific range (1.05-1.30) that provides sufficient crosslinking for mechanical strength while avoiding excessive sensitivity to moisture. This parameter optimization balances curing performance with environmental stability during the curing process.
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 composition provides improved mechanical, elastic, and adhesive properties, enabling effective bonding and sealing with resilience to environmental factors, while minimizing tension on the substrate.
Implementation Method 1
a moisture-curable composition comprising: a polyurethane P1 comprising at least two isocyanate groups; a polyurethane P2 comprising at least one isocyanate group and a group having the following formula (I): -N(H)-C(=O)-XR1
Implementation Method 2
polyurethane P1 is obtained by a process comprising a polyaddition reaction step E1: i) of a composition comprising at least one polyol; and ii) of a composition comprising at least one polyisocyanate
Data Source
AI summary
The present invention relates to a moisture-curable composition comprising: ∘ a polyurethane P1 comprising at least two isocyanate groups; ∘ a polyurethane P2 comprising at least one isocyanate group and a group having the following formula (I): [Chem 17] -N(H)-C(=O)-X-R1-Si(R2)p(OR3)3-p (I) in which: - X represents S or NR4, R4 representing H, an alkyl group, an aryl group, or a cycloalkyl group; - R1 represents a divalent hydrocarbon group comprising from 1 to 12 carbon atoms; - p is an integer equal to 0, 1, or 2, preferably 0 or 1; - each R2, identical or different, represents a linear or branched alkyl group comprising from 1 to 4 carbon atoms; - each R3, identical or different, represents a linear or branched alkyl group comprising from 1 to 4 carbon atoms; said composition being characterized in that the mass ratio polyurethane P1 : polyurethane P2 ranges from 50:50 to 99:1.