Silane-Modified Polyurethane Adhesive for High Tensile Strength
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Solution Overview
Problem
Existing silane modified polymers used in adhesives often suffer from high viscosity, low adhesion, poor low temperature performance, and low tensile strength, limiting their application and performance in adhesive compositions.
Innovation Solution
A curable adhesive composition comprising a combination of three silane modified polymers with specific molecular weight distributions and functional groups, including high molecular weight polyether blocks, low molecular weight polyether blocks, and terminal silyl alkoxy functional groups, which react to form a network with controlled elasticity and flexibility, reducing viscosity and enhancing adhesion and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silane modified polymers are used to improve adhesion and bond strength, then adhesion is improved, but viscosity increases
Solution Approach 1:
The invention divides the polymer system into three distinct silane modified polymers with different molecular weights and backbone structures (polyester, polyether, and polyurethane). This segmentation allows each component to contribute different properties: lower molecular weight polymers provide lower viscosity and better flow, while higher molecular weight polymers provide strength and adhesion. The combination achieves both low viscosity and high strength without the trade-off present in single-polymer systems.
Solution Approach 2:
The invention creates a composite adhesive system by combining three silane modified polymers with different chemical backbones (polyester, polyether, polyurethane) and different molecular weights. This composite approach allows the final adhesive to exhibit properties that none of the individual components could achieve alone: low viscosity from lighter components, high strength from heavier components, and flexibility from the diverse backbone structures.
2Strength
If highly crosslinked systems are formed to achieve high strength, then strength is improved, but flexibility is reduced
Solution Approach 1:
The invention applies local quality by creating regions of different crosslinking densities through the use of polymers with different molecular weights and backbone flexibilities. The lower molecular weight polymers form more densely crosslinked regions providing strength, while the higher molecular weight polymers with flexible backbones (especially polyether) create less densely crosslinked regions that maintain flexibility. This spatial variation in crosslinking density allows both high strength and flexibility to coexist.
Solution Approach 2:
The invention changes the parameter of backbone flexibility by selecting polymers with different backbone types (polyester, polyether, polyurethane). Polyether backbones inherently provide greater flexibility due to their molecular structure. By incorporating these flexible backbones into the crosslinked network, the system achieves high tensile strength while maintaining elongation and flexibility, overcoming the typical rigidity associated with highly crosslinked systems.
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 adhesion and tensile strength while maintaining flexibility, addressing the limitations of previous silane modified polymers by optimizing the molecular structure and reaction conditions to produce a more effective adhesive.
Implementation Method 1
In the presence of atmospheric moisture, polymers having silyl groups with hydrolyzable substituents are capable of condensing with one another at room temperature, splitting off the hydrolyzed residues
Implementation Method 2
polymers having silyl groups with hydrolyzable substituents are capable of condensing with one another at room temperature
Data Source
Figure 1
AI summary
This disclosure relates generally to adhesive compositions and more particularly to specific combinations of different silane modified polymers (SMP) for use in curable adhesive compositions.