Moisture-Curable Sealant Extensibility via Alpha-Functional Silanes
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Solution Overview
Problem
Moisture-curing compositions based on silane-functional polymers often lack sufficient extensibility and tear resistance while maintaining good adhesion properties, which is crucial for applications as elastic adhesives and sealants.
Innovation Solution
Incorporating specific amounts of α-functional organodialkoxysilanes and aminosilanes, such as N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, into the moisture-curing compositions to enhance extensibility, reactivity, and adhesion properties without using isocyanate groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aminosilanes are used to improve adhesion properties, then adhesion is enhanced, but extensibility is reduced
Solution Approach 1:
The patent changes the chemical parameters by introducing α-functional organodialkoxysilanes with specific molecular structures (formula I) that have different reactivity and flexibility characteristics compared to conventional aminosilanes. This parameter change allows the composition to achieve both good adhesion and extensibility by modifying the chemical composition rather than just adjusting concentrations
Solution Approach 2:
The patent creates a composite moisture-curing composition by combining silane-functional polymers with α-functional organodialkoxysilanes in specific ratios. This composite approach allows the different components to complement each other's properties, where the organodialkoxysilane provides extensibility while the silane-functional polymer provides adhesion, resolving the contradiction between these two properties
2Ease of operation
If extensibility is increased in cured compositions, then stretchability improves, but tear resistance is reduced
Solution Approach 1:
The patent modifies the chemical structure parameters by using α-functional organodialkoxysilanes with specific R1, R2, R3, and R4 groups that balance flexibility and strength. The molecular architecture parameters are optimized to provide chain mobility for extensibility while maintaining crosslink density for tear resistance
Solution Approach 2:
The patent applies local quality by creating different regions within the cured composition - the α-functional organodialkoxysilane provides localized flexibility and extensibility in the polymer chains, while the silane crosslinking provides localized strength and tear resistance at the crosslink points, allowing both properties to coexist in different locations of the material
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 significantly increased extensibility and tear resistance while maintaining high reactivity and adhesion, making them suitable for demanding applications as elastic adhesives and sealants.
Implementation Method 1
The silane groups have the property of hydrolyzing when they come into contact with moisture. Organosilanols are formed, i.e. organosilicon compounds containing one or more silanol groups (Si-OH groups)
Implementation Method 2
through subsequent condensation reactions, organosiloxanes, i.e. organosilicon compounds containing one or more siloxane groups (Si-O-Si groups)
Data Source
AI summary
The invention relates to moisture-curable compositions that are provided with increased elasticity while having good mechanical properties and adhesion. Said compositions contain at least on silane-functional polymer A, at least one aminosilane AS2, and at least one α-functional organodialkoxysilane at an amount of 0.6 to 5.0 parts by weight relative to 100 parts by weight of polymer A. Also disclosed are the production and use of the inventive compositions, especially as a sealant and adhesive.