Curable Composition for Optical Elements with Heat Resistance
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Solution Overview
Problem
Current cationically curable compositions for optical elements lack excellent thin-film curability, heat resistance, and thermal yellowing resistance, particularly under reflow soldering conditions, due to limitations with antimony, phosphorus, and borate initiators.
Innovation Solution
A curable composition comprising a cycloaliphatic epoxy compound, an oxetane compound, and a specific borate cationic-polymerization initiator, including an onium borate salt with a particular anionic and cationic moiety, which provides excellent thin-film curability and resistance to heat and thermal yellowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If antimony initiators are used for cationic polymerization, then thin-film curability is improved, but safety and environmental compliance deteriorate due to deleterious substance designation
Solution Approach 1:
The patent extracts and removes the harmful antimony initiator from the composition while maintaining the desired thin-film curability through alternative initiators (phosphorus or borate initiators) that do not pose safety or environmental concerns
Solution Approach 2:
The patent employs alternative initiators that are safer and environmentally friendly, effectively replacing the problematic antimony-based system with shorter-lived, less harmful chemical species that achieve the same functional outcome without the associated safety issues
2Object-affected harmful factors
If lead-free soldering is used for environmental reasons, then environmental compliance is improved, but heat resistance requirements increase to about 270°C
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific epoxy compounds, oxetane compounds, and cationic polymerization initiators that enable the cured product to withstand temperatures of about 270°C, thereby meeting the increased heat resistance requirements of lead-free soldering processes
3Reliability
If cationically curable compositions are used for optical elements, then cure inhibition by oxygen is reduced and shrinkage is minimized, but achieving excellent thin-film curability and heat resistance simultaneously becomes difficult
Solution Approach 1:
The patent creates a composite curable composition combining epoxy compounds, oxetane compounds, and specific cationic polymerization initiators in optimized ratios, achieving synergistic effects that simultaneously provide excellent thin-film curability, heat resistance, and resistance to cure inhibition by oxygen
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 forms a cured product with superior curability, transparency, heat resistance, and thermal yellowing resistance, enabling its use in optical elements and devices without additional processing steps, such as reflow soldering.
Implementation Method 1
The cationic-polymerization initiator includes (C) an onium borate salt
Implementation Method 2
via the application of light and/or heat, can form a cured product
Data Source
AI summary
Provided is a curable composition which has excellent thin-film curability and which can form, via the application of light and/or heat, a cured product having heat resistance and thermal yellowing resistance at excellent levels. This curable composition contains cationically curable compounds and a cationic-polymerization initiator. The cationically curable compounds include an epoxy compound (A) in an amount of 10 to 90 weight percent of the total weight of the cationically curable compounds, and an oxetane compound (B) in an amount of 5 to 40 weight percent of the total weight of the cationically curable compounds. The cationic-polymerization initiator includes an onium borate salt (C). The onium borate salt (C) preferably has an anionic moiety selected from [(C6H5)B(C6F5)3]-, [(C6H5)B((CF3CF2)2C6H2F)3]-3, and [(C6H5C6H4)B(C6F5)3]- and a cationic moiety selected from arylsulfonium ions.