Aromatic Polyiso(thio)cyanate Screening for Low-Haze, High-Index Optics
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Solution Overview
Problem
Existing methods for manufacturing high refractive index optics using isocyanates like m-xylylene diisocyanate are prone to issues such as bubbling and yellowing due to sensitivity to water and impurities, leading to inefficient quality control processes that delay product launch.
Innovation Solution
A method involving the measurement of aromatic polyiso(thio)cyanate transmittance at specific wavelengths to select high-quality materials for polymerization, ensuring at least 35% transmittance at 310 nm and optionally 60% at 320 nm, to produce low-bubble and low-Yellowness Index optical articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If isocyanates are used to manufacture high refractive index optics, then high refractive index optical materials are produced, but bubbling and yellowing occur due to sensitivity to water and impurities
Solution Approach 1:
The patent applies preliminary action by measuring the transmittance of isocyanate batches at 310 nm before polymerization to predict and prevent bubbling and yellowing. This pre-screening approach identifies suitable batches that will produce acceptable optical articles, avoiding the formation of defects during manufacturing.
Solution Approach 2:
The patent changes the parameter being measured from general quality assessment to specific UV transmittance at 310 nm. This parameter change enables prediction of bubbling and yellowing tendencies, allowing selection of isocyanate batches that maintain high refractive index while minimizing defects.
2Measurement precision
If quality control analysis is performed post-polymerization, then bubbles, haze, and yellowing can be determined, but manufacturing time and expense increase significantly
Solution Approach 1:
The patent performs quality assessment before polymerization by measuring UV transmittance of isocyanate batches. This preliminary measurement predicts the quality of the final optical article, eliminating the need for time-consuming post-polymerization analysis and accelerating product development.
Solution Approach 2:
The patent replaces complex post-polymerization quality control procedures with a simple UV transmittance measurement at 310 nm. This substitution of measurement methodology reduces time and expense while maintaining the ability to detect quality issues.
3Reliability
If visual inspection or absorbance measurement is used for quality control, then product quality can be assessed, but significant delays occur in bringing product to market
Solution Approach 1:
The patent performs quality prediction before polymerization by measuring UV transmittance of isocyanate batches. This ensures reliable product quality assessment while enabling faster decision-making and accelerating market launch by avoiding delays associated with post-polymerization testing.
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 allows for the production of high refractive index optical articles with reduced defects by predicting and preventing bubbling and yellowing, enhancing manufacturing efficiency and product quality.
Implementation Method 1
percent transmittance (% T) of the aromatic polyiso(thio)cyanate material used to prepare the polymerizable composition is measured at a wavelength of 310 nm±2 nm
Data Source
AI summary
A method of preparing a low bubbling and low yellowing, high refractive index polyurethane or polythiourethane is provided. A method of evaluating an aromatic polyiso(thio)cyanate material, such as an aromatic diisocyanate, e.g., m-xylylene cyanate, is provided. The method evaluates transmittance in a sample of the isocyanate to determine if the aromatic polyiso(thio)cyanate material will lead to unacceptable bubbling or yellowing in a high refractive index or high Abbe number polymer composition.