Polythiol Production via Sodium Sulfide Absorbance Control
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Solution Overview
Problem
There is a demand for improving the appearance characteristics of polythiourethane-based resin lenses, particularly in achieving a colorless and transparent finish, while existing methods may compromise other physical properties or process efficiency.
Innovation Solution
Controlling the absorbance of sodium sulfide to specific levels when producing polythiol compounds, ensuring the polythiol compound has an absorbance of 0.70 or less at 350 nm, which stabilizes the production of a colorless and transparent molded product with improved appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to manufacture polythiol compounds, then production can proceed with standard raw materials, but the color quality and transparency of the molded products deteriorate
Solution Approach 1:
The invention applies parameter changes by establishing specific absorbance thresholds for sodium sulfide (0.70 or less at 350 nm) and controlling the absorbance of the final polythiol compound (0.70 or less at 350 nm). This quantitative parameter control transforms the manufacturing process from using standard raw materials to using precisely controlled materials with specific optical properties, thereby resolving the contradiction between manufacturing precision and ease of manufacture.
2Manufacturing precision
If modifiers or additives are added to improve appearance characteristics, then color quality improves, but process efficiency and other physical properties deteriorate
Solution Approach 1:
The invention applies preliminary action by controlling the absorbance of sodium sulfide before it enters the polythiol synthesis process. By pre-screening the raw material (sodium sulfide) to ensure it meets the absorbance specification (0.70 or less at 350 nm), the invention prevents coloration problems from occurring in the first place, eliminating the need for subsequent modifications or additives that would reduce process efficiency.
3Manufacturing precision
If polythiol with higher purity is used, then resin color and transparency improve, but manufacturing complexity increases
Solution Approach 1:
The invention applies parameter changes by establishing a specific absorbance threshold (0.70 or less at 350 nm) for both sodium sulfide and the final polythiol compound. This single quantitative parameter serves as a comprehensive quality indicator that simplifies the manufacturing process - instead of monitoring multiple purity parameters, the process focuses on controlling absorbance, thereby achieving high resin color quality without excessive manufacturing complexity.
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 process enhances the color quality of polythiol compounds and the appearance of molded products, maintaining or improving other physical properties without reducing process efficiency.
Implementation Method 1
reacting a compound represented by following General Formula (3) with sodium sulfide to obtain a polyalcohol compound represented by following Formula (4)
Implementation Method 2
reacting the obtained polyalcohol compound represented by Formula (4) with a thiating agent to obtain a polythiol compound
Data Source
AI summary
A process for producing a polythiol compound, comprising: reacting a compound represented by following General Formula (3) with sodium sulfide to obtain a polyalcohol compound represented by following Formula (4), and reacting the obtained polyalcohol compound represented by Formula (4) with a thiating agent to obtain a polythiol compound, wherein an absorbance of 17.3% by weight aqueous solution of the sodium sulfide at a wavelength of 350 nm, which is measured with a quartz cell with an optical path length of 50 mm, is 0.70 or less.