Polythiol Synthesis Impurity Control for Optical Lens Clarity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The presence of impurities in epichlorohydrin compounds during the synthesis of polythiol compounds affects the coloring of polythiol compounds, leading to colored polyurethane resins, even when bis(2-hydroxyethyl)disulfide is controlled, and existing methods fail to minimize coloration effectively.
Innovation Solution
Controlling the total content of specific impurities in epichlorohydrin compounds to less than 0.5% by weight during the synthesis of polythiol compounds, specifically using 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane, to prevent coloring and achieve a low yellowness index in the resulting polythiol compounds and urethane optical materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polythiol compounds are synthesized using conventional epichlorohydrin compounds, then production cost and ease of manufacture are improved, but color characteristics deteriorate due to impurity-induced coloring
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative limits for impurity content in epichlorohydrin compounds (total impurities ≤ 0.5 wt%, with individual impurities like 1,2-dichloropropane ≤ 0.2 wt%, 2,3-dichloropropene ≤ 0.1 wt%, etc.). By controlling these compositional parameters, the coloring of polythiol compounds is prevented while maintaining conventional manufacturing processes and cost structures.
2Object-affected harmful factors
If polythiol compounds are synthesized with controlled bis(2-hydroxyethyl)disulfide content, then some coloring is reduced, but color characteristics still deteriorate due to other impurities
Solution Approach 1:
The patent applies segmentation by breaking down the impurity control into specific individual components rather than treating them as a single parameter. It identifies and limits multiple specific impurities (1,2-dichloropropane, 2,3-dichloropropene, 2-methyl-2-pentanol, 2-chloroallyl alcohol, cis-1,3-dichloropropene, trans-1,3-dichloropropene, 1,3-dichloroisopropanol, 1,2,3-trichloropropane, and 2,3-dichloropropanol) in addition to bis(2-hydroxyethyl)disulfide, addressing each harmful impurity separately to achieve comprehensive color control.
3Object-affected harmful factors
If high purity epichlorohydrin compounds are used to minimize coloring, then color characteristics are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies self-service by establishing clear, quantifiable specifications for epichlorohydrin compound purity that enable manufacturers to self-control the quality without requiring complex additional processing equipment or sophisticated purification systems. The defined impurity limits provide a straightforward quality standard that can be achieved through conventional manufacturing with proper process control.
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
This approach minimizes coloration in polythiol compounds and urethane optical materials, resulting in clear and transparent resins with improved color characteristics, suitable for optical applications such as lenses.
Implementation Method 1
reacting an epichlorohydrin compound with 2-mercaptoethanol to obtain a polyalcohol compound
Implementation Method 2
reacting the polyalcohol compound with thiourea to obtain a thiouronium salt
Implementation Method 3
hydrolyzing the thiouronium salt to obtain a polythiol compound containing 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane
Implementation Method 4
polymerizing the polythiol compound and a polyisocyanate compound to prepare a urethane resin
Data Source
AI summary
The present invention relates to a polythiol compound for a high quality optical material that exhibits excellent physical properties in terms of color, a composition for an optical material including the polythiol compound, and a method for producing an optical material. The present invention also relates to a method for preparing the polythiol compound. The method includes reacting an epichlorohydrin compound containing 0.5% by weight or less of impurities with 2-mercaptoethanol. The polythiol compound is prevented from being colored. In addition, the polythiol compound can be used to produce a urethane optical material that is prevented from being colored and has a low yellowness index and a good color. The polythiol compound can be used to produce various optical materials such as urethane optical materials. The optical material can be used to manufacture an optical lens having a good color. The optical lens can be widely used as a replacement for conventional optical lenses in various fields. Particularly, the optical lens can be used as a spectacle lens, a polarizing lens, a camera lens, or the like.