Thioepoxy Optical Material Color Stability via Intermediate Compounds
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Solution Overview
Problem
Thioepoxy lenses suffer from color instability and issues related to demolding and polymerization imbalance due to the presence of by-products from the conversion process of epoxy compounds to thioepoxy compounds.
Innovation Solution
A thioepoxy compound containing 4 to 15% by weight of 2,3-epoxypropyl(2,3-epithiopropyl)sulfide and/or 2,3-epoxypropyl(2,3-epithiopropyl)disulfide is used, which are intermediate compounds resulting from incomplete conversion of epoxy groups to thioepoxy groups, along with a polymerizable composition that may include polyisocyanate and polythiol compounds, and an internal release agent to stabilize the optical material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thioepoxy compounds are used as main monomers to achieve high refractive index and Abbe number, then optical performance is improved, but color instability occurs
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific intermediate compounds (2,3-epoxypropyl(2,3-epithiopropyl)sulfide and 2,3-epoxypropyl(2,3-epithiopropyl)disulfide) at controlled concentrations (0.1-10 wt%) into the thioepoxy compound system. This parameter adjustment resolves the color instability issue while maintaining the high refractive index and Abbe number properties, as the intermediate compounds act as stabilizers that prevent yellowing without compromising optical performance.
2Manufacturing precision
If epoxy compounds are completely converted to thioepoxy groups to improve purity, then by-products are reduced, but color stability deteriorates
Solution Approach 1:
The invention converts the harmful by-products of incomplete conversion into beneficial components. Instead of removing all intermediate compounds, the invention retains specific intermediate compounds (2,3-epoxypropyl(2,3-epithiopropyl)sulfide and 2,3-epoxypropyl(2,3-epithiopropyl)disulfide) at optimized concentrations, where they serve as color-stabilizing agents. This transforms what was traditionally considered impurity into a functional component that prevents yellowing.
3Measurement precision
If standard thioepoxy polymerization is used to achieve high refractive index, then optical properties are improved, but polymerization imbalance and demolding issues occur
Solution Approach 1:
The intermediate compounds serve as mediators in the polymerization system. They facilitate balanced polymerization reactions and improve demolding characteristics while maintaining high refractive index. The presence of these intermediate compounds at controlled levels acts as a buffer that regulates the polymerization process, preventing imbalance and ensuring reliable manufacturing.
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 approach results in a clear, transparent, high-quality thioepoxy optical material that is free from color instability and demolding issues, with improved polymerization balance, suitable for various lens applications such as corrective, sunglass, and camera lenses.
Implementation Method 1
a method for producing a thioepoxy optical material by polymerizing the polymerizable composition
Data Source
AI summary
The present invention relates to a thioepoxy compound for an optical material, a polymerizable composition including the thioepoxy compound, and a method for producing a thioepoxy optical material by polymerization of the polymerizable composition. The thioepoxy compound contains 4 to 15% by weight of 2,3-epoxypropyl(2,3-epithiopropyl)sulfide and/or 2,3-epoxypropyl(2,3-epithiopropyl)disulfide. The thioepoxy optical material is free from color instability, demolding, and polymerization imbalance, which are problems encountered in general thioepoxy optical materials.