Fluorene-Based UV Absorber for UV-A/UV-B Absorption Without Bleed-Out
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Solution Overview
Problem
Existing ultraviolet absorbers struggle to effectively absorb UV-A and UV-B rays without causing bleed-out, reducing mechanical strength, or staining, and are often costly to produce, making them unsuitable for general-purpose applications.
Innovation Solution
A fluorene compound with specific substituents is used to create a resin with excellent UV-A and UV-B absorption properties, featuring a polymerizable functional group to prevent bleed-out and adjust absorption wavelengths, combined with other ultraviolet absorbers for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic ultraviolet absorbers are used to absorb UV-B rays, then ultraviolet absorption performance is improved, but the absorbers need to be added in increased amounts which causes bleed-out or reduction in mechanical strength, heat resistance, or transparency
Solution Approach 1:
The patent changes the chemical structure parameters of the ultraviolet absorber by introducing a fluorene core with specific substituents (benzotriazole, triazine, or benzophenone groups) to achieve high absorption efficiency at lower concentrations, preventing bleed-out while maintaining mechanical strength
Solution Approach 2:
The patent creates composite ultraviolet absorber systems by combining the fluorene-based absorber with resin matrices (polyester, polycarbonate, acrylic), achieving synergistic effects that improve both UV absorption performance and resistance to bleed-out
2Reliability
If ultraviolet absorbers that absorb long-wavelength ultraviolet ray are used to improve UV-A absorption, then ultraviolet absorption performance for UV-A region is improved, but the absorbers absorb visible light region of 400 nm or more and are therefore often stained yellow
Solution Approach 1:
The patent precisely adjusts the molecular structure parameters of the fluorene-based absorber by modifying substituent groups and their positions to control the absorption spectrum, achieving peak absorption in UV-A region (320-400 nm) while minimizing absorption in the visible region above 400 nm, thus preventing yellow staining
3Reliability
If benzotriazole-based ultraviolet absorber is used to absorb UV-B rays, then ultraviolet absorption performance is improved, but the absorber has insufficient molar absorption coefficient for UV-A region and thus needs to be added at high concentration which causes whitening or embrittlement
Solution Approach 1:
The patent modifies the benzotriazole structure by incorporating it as a substituent on the fluorene core, which enhances the molar absorption coefficient in the UV-A region, allowing effective UV protection at lower concentrations and preventing whitening and embrittlement
4Reliability
If triazine-based ultraviolet absorber is used to absorb ultraviolet ray in wide wavelength band, then ultraviolet absorption performance is improved, but the absorber also absorbs visible light at 400 nm or more and is therefore disadvantageously susceptible to staining
Solution Approach 1:
The patent optimizes the triazine substituent structure on the fluorene core by adjusting electron-withdrawing groups and their positions, achieving broad UV absorption coverage while fine-tuning the HOMO-LUMO energy gap to reduce visible light absorption and prevent staining
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 fluorene-based ultraviolet absorber achieves selective absorption of UV-A and UV-B rays with improved bleed-out resistance and reduced staining, suitable for various applications including image display apparatuses and building materials.
Implementation Method 1
an ultraviolet absorber having a maximum absorption wavelength within a wavelength range of 280 to 400 nm
Data Source
AI summary
Provided are a novel ultraviolet absorber that has an excellent absorbing property for UV-A or UV-B, furthermore specifically absorbs only ultraviolet ray at a specific wavelength, and is capable of being used for general purposes, and an ultraviolet absorbing resin excellent in bleed-out resistance in addition to the characteristics described above. The ultraviolet absorber is a fluorene compound represented by the general formula (1) or a resin comprising the fluorene compound as a constituent unit.