Polymerizable Composition for Plastic Lens Optical Clarity
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Solution Overview
Problem
Existing methods for manufacturing plastic lenses using polyisocyanate and polythiol compounds face challenges in preventing optical distortion, striae, and turbidity due to high reaction heat and increased viscosity, which complicates thermal control and injection into molds.
Innovation Solution
A polymerizable composition comprising a polythiol compound with at least three mercapto groups and a polyiso(thio)cyanate compound without aromatic rings, where the thiol equivalent ratio is between 0.900 and 1.000, is used to suppress turbidity, optical distortion, and striae by controlling the polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a polyisocyanate compound and a polythiol compound are used to manufacture a plastic lens, then a high refractive index is achieved, but reaction heat increases making thermal control difficult
Solution Approach 1:
The patent modifies the chemical structure parameters of the polythiol compound by introducing cyclic structures (cyclic carbonate or cyclic carbamate groups) to control the polymerization reaction heat and improve thermal management during lens manufacturing
2Productivity
If the polymerization reaction proceeds at high rate, then production efficiency is improved, but viscosity increases making injection into mold difficult
Solution Approach 1:
The patent changes the molecular structure parameters of the polythiol compound by incorporating cyclic carbonate or cyclic carbamate groups, which modify the polymerization kinetics and viscosity characteristics to enable both high reaction rate and easy mold injection
3Ease of manufacture
If impurities are increased in raw materials, then manufacturing cost is reduced, but turbidity and hue quality worsen
Solution Approach 1:
The patent changes the chemical composition parameters of the polythiol compound by introducing cyclic carbonate or cyclic carbamate groups, which improve the chemical stability and purity of the polymerization reaction, thereby reducing turbidity and improving optical quality
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 solution effectively reduces turbidity, optical distortion, and striae in the transparent resin, resulting in a high refractive index, low dispersion, and improved heat resistance, durability, and impact resistance for the plastic lenses.
Implementation Method 1
a plastic lens having a high refractive index is obtained by a reaction between a polyisocyanate compound and a polythiol compound
Data Source
AI summary
Provided are a polymerizable composition which can suppress generation of turbidity, optical distortion, and striae in a transparent resin obtained therefrom, a transparent resin obtained from the polymerizable composition, an optical material containing the transparent resin, a plastic lens containing the optical material, and a method for manufacturing the transparent resin. The present invention is a polymerizable composition containing a polythiol compound having at least three mercapto groups and a polyiso(thio)cyanate compound. The polyiso(thio)cyanate compound contains only a polyiso(thio)cyanate compound having no aromatic ring, and a thiol equivalent ratio which is a measured value of a thiol equivalent of the polythiol compound with respect to a theoretical value of the thiol equivalent is 0.900 or more and less than 1.000.