Chromene Compound for Neutral Tint Photochromic Lenses
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Solution Overview
Problem
Current chromene compounds used in photochromic spectacle lenses face issues with initial coloration, fading speed, durability, and color stability, particularly when mixed with other photochromic compounds, leading to unwanted tint changes over time.
Innovation Solution
A novel chromene compound with an indeno(2,1-f)naphtho(1,2-b)pyran structure incorporating a hetero ring with sulfur atoms at the 6- and 7-positions, enhancing electron donating ability, which improves color optical density, fading speed, and durability while maintaining a neutral tint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple photochromic compounds are mixed to achieve neutral tint, then color balance is improved, but durability and color stability deteriorate due to different repeat durability between yellow and blue compounds
Solution Approach 1:
The patent merges the yellow and blue absorption characteristics into a single photochromic compound molecule. The compound contains both a yellow coloration development maximum (430-530 nm) and a blue coloration development maximum (550-650 nm) within the same molecular structure, eliminating the need to mix multiple compounds with different durability characteristics.
Solution Approach 2:
The patent creates a composite photochromic structure by combining multiple aromatic rings (indeno(2,1-f)naphtho(1,2-b)pyran core with additional fused or substituted aromatic systems) to generate multiple absorption maxima. This composite molecular architecture enables simultaneous yellow and blue coloration while maintaining uniform repeat durability.
2Productivity
If yellow compound has lower color development sensitivity than blue compound, then blue tint dominates during color development, but neutral tint balance is deteriorated
Solution Approach 1:
The patent applies local quality by creating distinct regions within the molecule that contribute differently to coloration. The molecular structure contains specific substituents and fused ring systems that locally enhance electron donating ability at different positions, creating optimized absorption characteristics at both yellow (430-530 nm) and blue (550-650 nm) wavelengths with balanced sensitivity.
3Quantity of substance
If absorption end extends beyond 420 nm into visible range, then color optical density is improved, but initial coloration increases
Solution Approach 1:
The patent optimizes the absorption spectrum parameters by adjusting the molecular structure to position the absorption end at or near 420 nm (ultraviolet boundary) rather than extending deep into the visible range. This parameter optimization maintains high color optical density through enhanced electron donating ability while preventing excessive initial coloration by limiting visible light absorption in the unexposed state.
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 novel chromene compound achieves high color optical density, rapid fading, and improved durability, ensuring consistent neutral tint performance even after repeated exposure to light, with enhanced heat resistance and reduced initial coloration.
Implementation Method 1
Photochromism is the reversible function of a certain compound that it changes its color swiftly upon exposure to light including ultraviolet light such as sunlight or light from a mercury lamp and returns to its original color when it is put in the dark by stopping its exposure to light.
Implementation Method 2
incorporating a hetero ring with sulfur atoms at the 6- and 7-positions, enhancing electron donating ability, which improves color optical density, fading speed, and durability while maintaining a neutral tint
Data Source
AI summary
A novel photochromic compound which develops a color of a neutral tint and has high color optical density, high fading speed and excellent durability. The present invention is a chromene compound having an indeno(2,1-f)naphtho(1,2-b)pyran structure as the basic skeleton in which a hetero ring having two hetero atoms including at least one sulfur atom is directly bonded to the 6-position and the 7-position of the indeno(2,1-f)naphtho(1,2-b)pyran structure via the hetero atom like the compound represented by the following formula (18).