Silane Modified Polymers Strength Flexibility Balance
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Solution Overview
Problem
Silane terminated polymers used in adhesives and sealants face a challenge in achieving a balance between increased strength and flexibility upon curing, as additives that enhance strength typically decrease elongation, and those that improve elongation often result in decreased strength.
Innovation Solution
A moisture curable composition comprising a silane modified polymer and a silane functional additive with specific structural differences, such as a linear polyethylene oxide backbone and silylalkoxy functional groups, which allows for improved tensile strength and elongation without the need for metal catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additives are used to enhance cured strength, then tensile strength is improved, but elongation and flexibility decrease
Solution Approach 1:
The patent changes the chemical parameters of the additive by specifying particular functional groups (carboxyl, hydroxyl, amino) and molecular weight ranges. These parameter changes enable the additive to provide both strength enhancement and flexibility retention through optimized molecular interactions in the cured polymer network.
Solution Approach 2:
The patent creates a composite system by combining silane-terminated polymer with specific additives that have complementary properties. The silane-terminated polymer provides the base structure while the additive with specific functional groups contributes both strengthening and flexibility, achieving a synergistic effect that resolves the contradiction.
2Productivity
If metal catalysts are used to accelerate curing, then curing speed is improved, but environmental hazards increase
Solution Approach 1:
The patent employs organic catalysts that are less persistent and less environmentally harmful compared to traditional metal catalysts. These organic catalysts perform their function during the curing process and do not leave harmful residues, effectively replacing problematic metal catalysts while maintaining curing efficiency.
Solution Approach 2:
The silane-terminated polymer system is designed to cure through moisture from the environment without requiring aggressive metal catalysts. The system utilizes naturally present atmospheric moisture as the curing agent, and the organic catalysts facilitate this self-service curing process, eliminating the need for harmful metal catalysts while maintaining acceptable curing speeds.
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 a surprising combination of increased strength and flexibility in the cured state, while reducing or eliminating the use of metal catalysts, thereby minimizing environmental hazards and maintaining excellent physical properties.
Implementation Method 1
In the presence of atmospheric moisture these silyl alkoxy terminated polymers are capable, at room temperature, of crosslinking and curing to form, depending on the concentration of alkoxysilyl groups and their configuration, long-chain polymers (thermoplastics), relatively wide-mesh three-dimensional networks (elastomers), or highly crosslinked systems (thermosets).
Implementation Method 2
In the presence of atmospheric moisture these silyl alkoxy terminated polymers are capable, at room temperature, of crosslinking and curing
Implementation Method 3
A moisture curable composition comprising a silane modified polymer and a silane functional additive
Data Source
Figure 1
AI summary
The disclosure relates to moisture curable compositions based on a combination of silane-modified polymer and silane functional additive, their manufacture and use. The silane functional additive is preferably prepared from a water miscible polyol having a functionality of about 2 to about 4 and/or a polyol having a tertiary nitrogen atom in the backbone and a functionality equal or greater than about 2.