UV-Curable Silicone Composition for Low Viscosity and Storage Stability
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Solution Overview
Problem
Conventional curable silicone compositions with mercapto functional compounds suffer from high viscosity, insufficient hardness of the cured product, and instability during storage, leading to gelation or increased viscosity before polymerization.
Innovation Solution
A curable silicone composition comprising organopolysiloxane with at least two alkenyl groups, mercapto functional organopolysiloxane with at least two thiol groups, a photopolymerization initiator, and 2,6-di-tert-butyl-4-methylphenol (BHT), resulting in a low viscosity, fast curing, and high hardness with improved storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mercapto functional compounds are used in UV curable silicone compositions, then the cured product achieves high hardness, but the composition exhibits high viscosity and storage instability leading to gelation
Solution Approach 1:
The patent introduces a specific photoinitiator system (combination of phosphine oxide compound and hydroxyacetophenone) as an intermediary that enables controlled polymerization. This mediator allows the composition to remain stable during storage while achieving complete curing and high hardness when exposed to UV light, resolving the contradiction between storage stability and final product hardness.
Solution Approach 2:
The patent optimizes the molecular structure parameters of the mercapto functional compound, specifically using compounds with controlled molecular weights and specific mercapto group densities. By changing these parameters, the composition achieves both low viscosity (improving processability) and high cured product hardness, while maintaining storage stability through controlled reactivity.
2Strength
If mercapto functional compounds are formulated to provide high hardness, then the cured product achieves sufficient hardness, but the composition shows insufficient storage stability causing gelation before polymerization
Solution Approach 1:
The patent incorporates stabilizers and carefully selects the photoinitiator system in advance to prevent premature reaction. The composition is formulated with components that remain inert during storage but become highly reactive upon UV exposure, ensuring reliability during storage while achieving the desired hardness after curing.
Solution Approach 2:
The dual photoinitiator system acts as a controlled intermediary that keeps the mercapto functional compounds stable during storage. Upon UV irradiation, the photoinitiators activate and trigger the polymerization reaction, converting the stable storage state into the high-hardness cured state, thus resolving the reliability issue.
3Ease of manufacture
If conventional mercapto functional compounds are used, then the composition can be formulated, but the viscosity is too high and the cured product hardness is insufficient
Solution Approach 1:
The patent fundamentally changes the parameters of the mercapto functional compound selection, using compounds with specific molecular weight ranges and controlled mercapto group densities. This parameter optimization enables the formulation of low-viscosity compositions that still achieve high cured product hardness, resolving both the manufacturability and strength requirements.
Solution Approach 2:
The patent creates a composite system combining the mercapto functional organopolysiloxane with specific photoinitiators and stabilizers. This composite formulation achieves low viscosity for easy manufacturing while the synergistic interaction of components ensures high cured product hardness, resolving the contradiction between ease of manufacture and product strength.
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 quick curing with low viscosity and high hardness while maintaining storage stability, overcoming the limitations of conventional compositions.
Implementation Method 1
a curable silicone composition and a cured product of the curable silicone composition... UV curable silicone compositions... at least one photopolymerization initiator
Implementation Method 2
mercapto functional compounds... at least one mercapto functional organopolysiloxane having at least two thiol groups per molecule... aliphatic unsaturated carbon-carbon bonds
Implementation Method 3
2,6-di-tert-butyl-4-methylphenol... storage stability... prevent gelation or an increase of viscosity while they are stored
Data Source
AI summary
The present invention relates to a curable silicone composition comprising: (A) at least one organopolysiloxane having at least two alkenyl groups per molecule; (B) at least one mercapto functional organopolysiloxane having at least two thiol groups per molecule; (C) at least one photopolymerization initiator; and, (D) 2,6-di-tert-butyl-4-methylphenol (BHT), wherein the composition has a viscosity of less than 200 mPa·s at 25° C.