Curable Composition for High Elongation Sealants
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Solution Overview
Problem
Cured products from amine curing catalyst and reactive silyl group-containing organic polymers exhibit low elongation and low elastic recovery, making them unsuitable for construction sealants with significant joint movement.
Innovation Solution
A curable composition combining a reactive silyl group-containing organic polymer with a compound having 2 to 10 ethyloxy groups and no amino group, along with an amidine compound as a silanol condensation catalyst, to enhance elongation and elastic recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amine curing catalyst is used with reactive silyl group-containing organic polymer, then curability is improved, but elongation and elastic recovery deteriorate
Solution Approach 1:
The invention changes the chemical structure parameters of the polymer by introducing specific chain end structures (formulae 1 and 2 with specific R1, R2, X, and W groups) to achieve high elongation and elastic recovery while maintaining fast cure rate with amine catalysts
Solution Approach 2:
The invention creates a composite system combining specifically structured reactive silyl group-containing organic polymer with amine curing catalyst, where the polymer has controlled molecular weight (3000-100000) and specific chain end structures that work synergistically with the catalyst to achieve both fast curing and high elasticity
2Productivity
If organotin compounds are used as condensation catalyst, then curability is improved, but environmental friendliness deteriorates due to toxicity
Solution Approach 1:
The invention replaces persistent toxic organotin compounds with environmentally benign amine curing catalysts that are less harmful and can be used in smaller amounts, achieving comparable curability without the environmental persistence and toxicity of tin compounds
Solution Approach 2:
The invention changes the catalyst type parameter from organotin compounds to amine compounds, and adjusts the polymer structure parameters (chain end structures, molecular weight) to optimize performance with the environmentally friendlier catalyst system
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 high elongation and elastic recovery, making it suitable for construction sealants that experience significant joint movement, with the cured product showing an elongation at break of 380% or higher and elastic recovery of 65% or higher.
Implementation Method 1
the hydrolysis and other reactions of the silyl group due to factors such as moisture even at room temperature, thereby forming rubbery cured products
Implementation Method 2
crosslinked by siloxane bond formation, which involves the hydrolysis and other reactions of the silyl group
Implementation Method 3
crosslinked by forming a siloxane bond
Implementation Method 4
the use of even metals other than tin can be undesirable depending on the application, and the combined use of carboxylic acids and amine compounds has a problem in that it is less likely to result in high cure rate
Data Source
AI summary
Provided is a curable composition which is free of organotin compounds to be environmentally friendly and whose cured product shows high elongation and high elastic recovery to be suitable particularly as a sealant. The present invention relates to a curable composition containing a reactive silyl group-containing organic polymer (A) which has a highly active reactive silyl group at a molecular chain end, and a compound (B) having 2 to 10 ethyloxy groups in its molecule but having no amino group in its molecule, the compound (B) being a C1-C20 saturated hydrocarbon having one alkoxysilyl group, a C1-C20 hydrocarbon having two or more alkoxysilyl groups, or a C1-C20 polycarboxylic acid ester.