Curable Silicone Compositions with Non-Harmful Leaving Groups
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Solution Overview
Problem
Current curable silicone compositions face challenges with storage stability and adhesion to certain substrates, particularly plastics and concrete, due to the release of aggressive byproducts like butan-2-one oxime, which is carcinogenic and has an unpleasant odor, and the use of α-carbalkoxyalkoxy crosslinkers does not consistently provide good adhesion and stability.
Innovation Solution
Development of curable compositions based on polyorganosiloxanes endcapped with specific silane groups, combined with a capped adhesion promoter and a curing catalyst, which release hydroxycarboxylic acid esters or amides during crosslinking, ensuring excellent storage stability and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oximosilane crosslinkers are used to achieve neutral crosslinking without aggressive byproducts, then adhesion and storage stability are improved, but carcinogenic and foul-smelling byproducts are released
Solution Approach 1:
The patent extracts and removes the harmful oxime leaving group from the crosslinking reaction system by replacing oximosilane crosslinkers with alternative silane compounds that have non-harmful leaving groups, thereby eliminating the carcinogenic and foul-smelling byproducts while maintaining the beneficial neutral crosslinking characteristics
Solution Approach 2:
The patent converts the previously harmful oxime byproduct into a beneficial situation by selecting silane crosslinkers with leaving groups that produce harmless or beneficial byproducts, thus transforming the harmful crosslinking reaction into an environmentally friendly process that maintains good adhesion and storage stability
2Object-generated harmful factors
If α-carbalkoxyalkoxy crosslinkers are used to achieve neutral crosslinking, then aggressive byproduct release is reduced, but adhesion to certain substrates and storage stability are insufficient
Solution Approach 1:
The patent changes the chemical parameters of the crosslinker by selecting silane compounds with specific leaving groups (such as carboxylic acid esters, amides, or nitriles) that differ from both the harmful oximes and the insufficient α-carbalkoxyalkoxy groups, thereby achieving a balance between neutral crosslinking, good adhesion, and excellent storage stability
Solution Approach 2:
The patent employs a composite approach by combining specific silane crosslinkers with particular polyorganosiloxanes and adhesion promoters to create a formulated composition that achieves synergistic effects, providing both neutral crosslinking characteristics and superior adhesion to challenging substrates like plastics and concrete
3Reliability
If silane crosslinkers with hydroxycarboxylic acid esters or amides are used, then storage stability and adhesion are improved, but the composition becomes more complex
Solution Approach 1:
The patent identifies silane crosslinkers with hydroxycarboxylic acid esters or amides that serve multiple functions: they provide neutral crosslinking, ensure excellent adhesion to various substrates including plastics and concrete, and deliver superior storage stability, thereby reducing the need for additional specialized additives and simplifying the overall formulation
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 high storage stability and reliable curing at room temperature, maintaining good adhesion to various substrates without the drawbacks of aggressive byproduct release, such as the use of butan-2-one oxime, and provide improved performance on challenging materials like plastics and concrete.
Implementation Method 1
In the presence of atmospheric moisture these alkoxysilane-terminated polymers are able to condense with elimination of the alkoxy groups
Implementation Method 2
In the presence of atmospheric moisture these alkoxysilane-terminated polymers are able to condense with elimination of the alkoxy groups
Implementation Method 3
This can be carried out optionally in the presence of a catalyst, whereby the catalyst is to mediate the endcapping selectively without simultaneously curing the polyorganosiloxane
Data Source
AI summary
The invention relates to curable compositions based on polyorganosiloxanes with special silicon-containing terminal groups, a special capped adhesion promoter, and a curing catalyst. These compositions have improved adhesion properties and excellent storage stability. The invention relates furthermore to the use thereof.