Silane Moisture-Curable Hot Melt Adhesion
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Solution Overview
Problem
Existing silane-based moisture-curable compositions lack initial mechanical strength (green strength) and adhesion to substrates like glass and metal, while polyurethane reactive hot melts provide good green strength but suffer from blistering and poor adhesion.
Innovation Solution
A silane-reactive moisture-curable hot melt composition incorporating an acrylate-urethane copolymer with active hydrogen groups, combined with polyols and polyisocyanates, and end-capped with moisture-curable isocyanato silanes, which forms a cross-linking network for enhanced adhesion and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silane-based moisture-curable compositions are used, then adhesion to substrates is improved, but initial mechanical strength (green strength) deteriorates
Solution Approach 1:
The composition is segmented into multiple functional components: silane-modified polyurethane prepolymers provide adhesion, thermoplastic polymers provide green strength, and moisture-curable crosslinking agents provide final curing. This segmentation allows each component to fulfill its specific function without compromising others.
Solution Approach 2:
The invention uses composite materials by combining silane-modified polyurethane prepolymers with thermoplastic polymers and moisture-curable crosslinking agents. This composite approach integrates the adhesion benefits of silane with the mechanical strength benefits of thermoplastics and the curing benefits of moisture-responsive crosslinking agents.
2Strength
If polyurethane reactive hot melts are used, then initial mechanical strength (green strength) is improved, but adhesion to substrates deteriorates
Solution Approach 1:
The invention merges the beneficial properties of polyurethane reactive hot melts (green strength) with silane-based compositions (adhesion) by using silane-modified polyurethane prepolymers as the base material. This merging allows the composition to achieve both green strength and adhesion simultaneously.
3Strength
If various additives and tackifiers are added to enhance green strength, then initial mechanical strength is improved, but composition complexity increases
Solution Approach 1:
The invention changes the chemical parameters of the base material by using silane-modified polyurethane prepolymers with specific molecular weights and silane content. This parameter change allows the composition to achieve green strength through the modified polymer structure itself rather than requiring multiple additive components.
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 achieves long open time, high initial green strength, non-blistering, excellent UV resistance, and strong adhesion to glass and metal, along with improved weather resistance.
Implementation Method 1
moisture-curable isocyanato silane groups are incorporated onto a copolymer backbone... alkoxy functionality to enable and enhance moisture curing
Implementation Method 2
forms a cross-linking network for enhanced adhesion and mechanical strength
Implementation Method 3
acrylate-urethane copolymer by reacting a composition which includes: a.) at least one polyacrylate containing active hydrogen groups; b.) at least one polyol; c.) at least one polyisocyanate
Data Source
AI summary
The present invention relates to moisture-curable silane-reactive hot melt compositions having an acrylate-urethane copolymer moiety. Desirably, the silane groups contain alkoxy functionality to enable and enhance moisture curing. Such compositions provide enhanced green strength without sacrificing other desirable properties.