Polythiourethane Lens Composition Catalyst pKa Control
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Solution Overview
Problem
The existing non-tin catalysts used in the production of polythiourethane resins for plastic lenses have limitations, including insufficient pot life, heat resistance, and control over polymerization, leading to optical nonuniformities such as striae and cloudiness, and difficulties in releasing the molded product from the mold during polymerization.
Innovation Solution
A polymerizable composition comprising a compound with a pKa value of 1 to 9, a di- or higher functional iso(thio)cyanate compound, and a di- or higher functional active hydrogen compound, specifically selected from certain compounds and their combinations, which ensures adequate pot life and control over polymerization, thereby improving the optical and thermal properties of the resulting plastic lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If organotin catalyst is used for producing polythiourethane resin, then catalyst activity and reaction speed are improved, but toxicity and environmental harm increase
Solution Approach 1:
The patent replaces persistent organotin catalysts with biodegradable enzyme catalysts (lipase, protease, or amylase) that can be decomposed after use, eliminating long-term environmental contamination while maintaining catalytic functionality during the reaction process
Solution Approach 2:
The patent introduces a specific compound (Formula 1) as a catalyst that mediates the reaction between isocyanate and thiol compounds, providing an intermediate solution that avoids both the toxicity of organotin catalysts and the insufficient activity of conventional alternatives
2Object-affected harmful factors
If conventional non-tin catalysts are used, then toxicity is reduced, but pot life and polymerization control are insufficient
Solution Approach 1:
The patent optimizes the molecular structure parameters of the catalyst (Formula 1) including specific R1-R6 groups and pKa values to achieve the desired balance between extended pot life and adequate polymerization control, replacing conventional catalysts with insufficient duration
3Object-affected harmful factors
If conventional non-tin catalysts are used, then toxicity is reduced, but heat resistance and optical uniformity deteriorate
Solution Approach 1:
The patent adjusts the chemical parameters of the catalyst including pKa value range and molecular structure to control the polymerization reaction more precisely, preventing optical defects like striae and cloudiness while maintaining non-toxicity
4Object-affected harmful factors
If conventional non-tin catalysts are used, then toxicity is reduced, but polymerization control and mold release difficulty increase
Solution Approach 1:
The patent modifies the catalyst parameters including basicity and molecular structure to achieve optimal polymerization control that prevents excessive adhesion to mold surfaces, enabling easy release of the cured lens while maintaining safety
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 composition effectively extends pot life, enhances polymerization control, and reduces optical defects like cloudiness and striae, resulting in a plastic lens with improved refractive index, heat resistance, and releasability.
Implementation Method 1
a polymerizable composition for an optical material including: (A) a compound of which pKa value is 1 to 9; (B) a di- or higher functional iso(thio)cyanate compound; and (C) a di- or higher functional active hydrogen compound
Data Source
AI summary
A polymerizable composition for an optical material of the present invention includes (A) a compound of which pKa value is 1 to 9, (B) a di- or higher functional iso(thio)cyanate compound, and (C) a di- or higher functional active hydrogen compound.