Curable Silicone Compositions with Hydroxycarboxylate Crosslinkers
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Solution Overview
Problem
Curable silicone compositions face challenges in achieving sufficient storage stability, particularly when combined with conventional components like curing catalysts and adhesion promoters, due to the release of aggressive compounds during crosslinking, which can corrode materials and have unpleasant odors.
Innovation Solution
The development of curable compositions based on polyorganosiloxanes that include a silane crosslinker releasing α-hydroxycarboxylic acid esters or α-hydroxycarboxylic acid amides, in conjunction with an aminosilane and a tin compound, within a specific molar ratio, excluding epoxysilanes, to enhance storage stability and curing efficiency at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional crosslinkers (acidic or basic silanes) are used, then crosslinking efficiency is improved, but storage stability deteriorates due to release of aggressive compounds that can corrode materials
Solution Approach 1:
The patent converts the harmful effect of aggressive compound release by selecting neutral crosslinkers that release non-aggressive byproducts (alcohols or oximes instead of acids or amines). This resolves the contradiction by maintaining crosslinking efficiency while eliminating corrosion and material degradation issues.
Solution Approach 2:
The patent changes the chemical parameter of the crosslinker from acidic/basic to neutral type, specifically using crosslinkers that release alcohols or oximes. This parameter change eliminates the harmful corrosive effects while preserving the crosslinking function.
2Reliability
If oximosilane crosslinkers are used, then adhesion and storage stability are improved, but harmful factors worsen due to release of cancer-suspected oximes with intense foul odor
Solution Approach 1:
The patent converts the harmful oxime-release mechanism into a beneficial alcohol-release mechanism by selecting crosslinkers with different hydrolyzable groups. This eliminates the toxic and odorous oxime byproducts while maintaining the adhesion and storage stability benefits.
Solution Approach 2:
The patent changes the hydrolysis product parameter from oxime to alcohol by selecting crosslinkers with alkoxy or hydroxycarboxylate groups instead of oxime-forming groups. This parameter change eliminates toxicity and odor while preserving adhesion properties.
3Object-affected harmful factors
If alkoxy crosslinkers are used, then neutral crosslinking is achieved, but storage stability deteriorates due to multiple formulation problems
Solution Approach 1:
The patent changes the crosslinker chemistry from simple alkoxy to hydroxycarboxylate-containing silanes, which provide both neutral crosslinking and improved storage stability through the specific chemical structure and reactivity of the hydroxycarboxylate groups.
Solution Approach 2:
The patent uses composite crosslinking systems combining silane crosslinkers with specific hydroxycarboxylate groups and complementary additives to achieve both neutral crosslinking and enhanced storage stability, resolving the formulation problems of simple alkoxy systems.
4Speed
If curable compositions are formulated with high reactivity crosslinkers, then curing speed is improved, but storage stability worsens due to premature reaction
Solution Approach 1:
The patent changes the reactivity parameter of the crosslinker to achieve optimal balance: hydroxycarboxylate-containing silanes provide sufficient curing speed while their specific chemical structure prevents premature hydrolysis and maintains storage stability.
Solution Approach 2:
The patent discards overly reactive crosslinkers that cause premature curing and recovers optimal performance by selecting crosslinkers with controlled reactivity through the hydroxycarboxylate functional groups, achieving both fast curing and stable storage.
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
These compositions exhibit high storage stability and reliable curing in the presence of atmospheric moisture, even at room temperature, while avoiding the release of aggressive compounds, thus improving handling and material compatibility.
Implementation Method 1
the silane crosslinker releasing α-hydroxycarboxylic acid esters or α-hydroxycarboxylic acid amides
Implementation Method 2
a tin compound as a curing catalyst
Implementation Method 3
an aminosilane... within a specific molar ratio
Data Source
AI summary
The invention relates to a curable composition, containing(A) at least one polyorganosiloxane, which has at least one hydroxy group bound to a silicon atom,(B) at least one silane of the formula (1):Si(R1)m(R2)n(R3)4−(m+n) (1), as defined herein,(C) at least one aminosilane, and(D) at least one tin compound,wherein the composition is free of epoxysilane and the molar ratio of the aminosilane to the tin compound is 1:1 to 50:1, as well as to the preparation and use thereof.