Polythiol Composition Oxygen Reduction for Lens Stability
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Solution Overview
Problem
The quality of polythiol compositions used in optical materials deteriorates due to active oxygen, leading to adverse effects on the optical properties of lenses, and existing methods to remove oxygen are costly and inefficient.
Innovation Solution
A polythiol composition is treated with a reducing agent to reduce active oxygen content to 200 ppm or less, using agents like lithium aluminum hydride, sodium borohydride, or sodium thiosulfate, followed by removal of the agent, to enhance storage stability and prevent byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polythiol is stored for long-term, then optical lens production is enabled, but active oxygen generates byproducts and deteriorates quality
Solution Approach 1:
A chelating agent serves as an intermediary substance that binds to metal ions (catalysts) present in the polythiol composition, preventing these catalysts from facilitating the oxidation of thiol groups by active oxygen. This intermediary action blocks the harmful reaction pathway without affecting the primary polymerization function, thereby preventing byproduct generation during storage while maintaining long-term stability.
2Reliability
If thiol group content is increased for high refractive index, then optical properties improve, but reactivity increases causing self-bonding and byproduct formation
Solution Approach 1:
The chelating agent acts as a protective intermediary that selectively binds to catalyst metal ions, creating a controlled environment where high concentrations of thiol groups can exist without undergoing unwanted self-bonding reactions. This allows the formulation to achieve high refractive index through increased thiol content while the chelating agent prevents the harmful side reactions that would otherwise occur.
3Object-affected harmful factors
If oxygen removal from all raw materials is attempted, then active oxygen content decreases, but production cost significantly increases
Solution Approach 1:
Instead of performing oxygen removal from all raw materials during the manufacturing process (which would be costly and complex), the invention applies a preliminary protective action by adding the chelating agent to the final polythiol composition. This preliminary protection prevents active oxygen from causing harm during storage, eliminating the need for expensive oxygen removal operations on multiple raw materials while still achieving the desired low active oxygen effect.
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 method effectively reduces active oxygen in polythiol compositions, maintaining optical properties and stability over long-term storage, preventing changes in color, viscosity, and byproduct formation, ensuring high-quality optical materials like eyeglass lenses.
Implementation Method 1
A polythiol composition is treated with a reducing agent to reduce active oxygen content to 200 ppm or less
Implementation Method 2
A polythiol composition is treated with a reducing agent to reduce active oxygen content
Data Source
AI summary
Disclosed is to prevent generation of byproducts or a deterioration in the physical properties of a polythiol composition that may be caused by active oxygen during storage thereof by way of controlling the content of active oxygen in the polythiol composition after the synthesis of the polythiol. As a result, it is possible to enhance the long-term storage stability of a polythiol composition after it has been synthesized until it is used in the polymerization reaction.