Polythiol Composition for Plastic Lens Resin Heat Resistance and Dyeability
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Solution Overview
Problem
Existing polythiol compositions for manufacturing resins used in plastic lenses struggle to achieve a balance between heat resistance and dyeability.
Innovation Solution
A polythiol composition comprising specific polythiol compounds, such as 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane and 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, optimized for peak area ratios in high performance liquid chromatography measurements to enhance the balance between heat resistance and dyeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a polythiol compound is used to manufacture resin for plastic lenses, then heat resistance can be improved, but dyeability deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the polythiol compound by specifying precise molecular formulas (compounds of formulae 1-3 with specific R1-R6 groups) and controlling the average number of mercapto groups per molecule (2.95-3.05). This parameter optimization enables the resin to achieve both high heat resistance (Tg ≥ 100°C) and good dyeability simultaneously
Solution Approach 2:
The patent creates a composite polythiol compound structure that combines specific cyclic sulfide rings (1,3-dithiolane, 1,3-dithiane, 1,4-dithiane) with controlled mercapto group distribution. This composite molecular architecture integrates the heat resistance properties from the cyclic structures with the dyeability properties from the mercapto groups, resolving the contradiction between these two properties
2Temperature
If polythiol compound structure is optimized for heat resistance, then thermal properties improve, but optical transparency deteriorates
Solution Approach 1:
The patent optimizes molecular weight parameters and mercapto group density (controlling average number per molecule to 2.95-3.05) to achieve a balance where the glass transition temperature reaches at least 100°C while maintaining optical transparency (YI value ≤ 8.0). The specific molecular structure parameters prevent excessive chain entanglement that would scatter light while ensuring sufficient thermal stability
3Ease of manufacture
If polythiol compound synthesis is simplified, then manufacturing ease improves, but manufacturing precision deteriorates
Solution Approach 1:
The patent specifies precise compositional parameters (average number of mercapto groups per molecule: 2.95-3.05, content of compounds of formulae 1-3: 90 mass% or more) that can be controlled through straightforward synthesis methods using common reagents like epichlorohydrin and sodium sulfide. These parameter targets provide clear manufacturing guidance while ensuring high composition control for consistent resin performance
Data Source
AI summary
A polythiol composition includes a polythiol compound (A) including at least one of 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, and a polythiol compound (B) that is 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane.