UV Curable Silicone Composition Gelation and Coloration Control
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Solution Overview
Problem
UV curable silicone compositions containing mercapto functional compounds often experience gelation before polymerization starts and may undergo coloration during the curing process, which affects the quality of the cured product.
Innovation Solution
Incorporating a specific combination of photopolymerization initiators, polymerization inhibitors such as alkoxylated polyol derived (meth)acrylates or quinone derivatives, and antioxidants like hindered phenol-type antioxidants into the composition to suppress gelation and coloration, resulting in a clear cured silicone product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mercapto functional compounds are added to UV curable silicone composition to provide high hardness, then the hardness of cured product is improved, but gelation occurs before polymerization starts
Solution Approach 1:
The patent applies preliminary action by adding a polymerization inhibitor to the composition before UV irradiation. This inhibitor prevents premature polymerization reactions between the mercapto functional compound and aliphatic unsaturated group during storage and handling, allowing the composition to remain stable until the intended curing moment when UV light is applied.
Solution Approach 2:
The polymerization inhibitor acts as an intermediary substance that temporarily blocks the reactive interaction between the mercapto functional compound and aliphatic unsaturated group. This mediator prevents direct harmful reaction while allowing the composition to maintain its designed functionality for later controlled curing.
2Strength
If mercapto functional compounds are used in UV curable silicone composition, then high hardness is achieved, but coloration occurs during curing process
Solution Approach 1:
The antioxidant serves as an intermediary that protects the mercapto functional compound from oxidation during the UV curing process. By introducing this protective substance, the patent prevents the coloration that would otherwise occur due to oxidative degradation of the mercapto groups, while still allowing the desired hardness to be achieved.
Solution Approach 2:
The antioxidant provides beforehand cushioning by being present in the composition before UV irradiation begins. This pre-existing protective agent cushions against the harmful oxidative effects that would cause coloration during the curing process, ensuring the mercapto functional compound can fulfill its hardness-providing function without degradation.
3Productivity
If polymerization is initiated by UV irradiation, then curing is achieved, but gelation and coloration occur simultaneously
Solution Approach 1:
The patent introduces two types of intermediaries: a polymerization inhibitor that prevents premature gelation and an antioxidant that prevents coloration. These mediators allow UV irradiation to proceed for effective curing while blocking the harmful side reactions that would otherwise occur simultaneously with the polymerization process.
Solution Approach 2:
The patent effectively extracts or separates the harmful effects (gelation and coloration) from the useful effect (curing). By removing the ability of the composition to gel prematurely through inhibitor addition and removing the tendency to color through antioxidant addition, the patent isolates the desired curing function from its unwanted side effects.
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 described composition effectively prevents gelation and coloration, ensuring a stable pot-life and producing clear, high-quality cured silicone products with improved properties.
Implementation Method 1
UV curable silicone composition comprising (A) at least one organopolysiloxane having at least two alkenyl groups per molecule, (B) at least one mercapto functional compound having at least two thiol groups per molecule, and (C) at least one photopolymerization initiator
Data Source
AI summary
The present invention relates to a UV curable silicone composition comprising at least one organopolysiloxane having at least two alkenyl groups per molecule; at least one mercapto functional organic compound having at least two thiol groups per molecule; at least one photopolymerization initiator; and at least one polymerization inhibitor comprising at least one alkoxylated polyol derived (meth)acrylate or at least one quinone derivative compound, and/or at least one antioxidant, wherein the composition comprises the photopolymerization initiator selected from intramolecular hydrogen abstraction type photopolymerization initiators, or the composition comprises the polymerization inhibitor.