Polythiol Composition Ratios for Durable, Uniform Optical Lenses
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Solution Overview
Problem
Existing polythiol compounds used in manufacturing polyurethane resins for optical lenses suffer from issues such as reduced transparency, optical non-uniformity, and mechanical property changes due to variations in reactivity, molecular weight, and functional group number, leading to defects like stria and white turbidity.
Innovation Solution
A polythiol composition comprising a first trifunctional polythiol compound and a second polythiol compound with a higher molecular weight, controlled in a specific ratio, is used to regulate reaction rate and glass transition temperature, improving mechanical durability and optical uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polythiol compound is used to manufacture optical lenses, then the lens can be produced with desired mechanical properties, but optical defects such as reduced transparency, optical non-uniformity, stria, and white turbidity may occur due to variations in reactivity, molecular weight, and functional group number
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution of the polythiol compound. Specifically, it limits the proportion of components with molecular weights below 150 g/mol to 5 wt% or less and components above 350 g/mol to 10 wt% or less. This parameter control optimizes both the reactivity (affecting mechanical durability) and the uniformity of the cured resin (affecting optical quality), resolving the contradiction between mechanical strength and optical uniformity.
Solution Approach 2:
The patent applies local quality by differentiating the requirements for different molecular weight components of the polythiol compound. It specifically controls the proportions of low molecular weight components (below 150 g/mol) and high molecular weight components (above 350 g/mol) separately, recognizing that each range contributes differently to the final product properties. This localized control allows optimization of both mechanical durability and optical uniformity by tailoring the molecular weight distribution to specific performance requirements.
2Productivity
If the reactivity of the polythiol compound is increased to improve reaction rate, then productivity increases, but transparency and optical uniformity are reduced
Solution Approach 1:
The patent resolves this contradiction through parameter changes by controlling the molecular weight distribution of the polythiol compound. By limiting low molecular weight components (below 150 g/mol) to 5 wt% or less, the patent reduces excessive reactivity that causes optical defects while maintaining sufficient reaction rate for productivity. This parameter control ensures that the polythiol compound reacts at an appropriate rate without causing transparency issues or optical non-uniformity in the final lens product.
Data Source
AI summary
A polythiol composition according to exemplary embodiments includes a first polythiol compound which provides a maximum peak in a high performance liquid chromatography (HPLC) analysis graph obtained at a wavelength of 230 nm, and a second polythiol compound having a molecular weight greater than that of the first polythiol compound and represented by C9H20S6. A ratio of a peak area of the second polythiol compound to a peak area of the first polythiol compound, which are measured through the HPLC analysis graph at the wavelength of 230 nm, is 0.05 to 5.0%.