Benzotriazole UV Absorber with Ester Groups for Optical Materials
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Solution Overview
Problem
Existing optical materials face challenges in effectively blocking UV and phototoxic blue light without impairing polymerization, mechanical properties, or causing cosmetic defects like haze and yellowness, which are difficult to incorporate and process efficiently.
Innovation Solution
Incorporating benzotriazole derivatives with ester solubilizing groups into polymerizable compositions to enhance compatibility and processing speed, allowing for efficient UV and blue light filtering in ophthalmic lenses while maintaining transparency and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional UV absorbers (benzotriazole and benzophenone derivatives) are incorporated into optical materials, then UV light blocking is improved, but blue light filtering is insufficient and polymerization may be impaired
Solution Approach 1:
The patent modifies the chemical structure of benzotriazole UV absorbers by introducing ester solubilizing groups (such as -COOR where R is alkyl or aryl), which changes the physical and chemical parameters of the molecule. This structural modification enables the UV absorber to function effectively at lower concentrations while maintaining polymerization integrity and providing enhanced blue light filtering capabilities.
Solution Approach 2:
The invention creates a composite optical material system combining polymerizable compounds (monomers and/or oligomers) with ester-modified benzotriazole UV absorbers. This composite formulation achieves synergistic effects where the ester group enhances solubility and compatibility, allowing simultaneous UV protection, blue light filtering, and maintained polymerization reactivity.
2Object-affected harmful factors
If UV absorbers are incorporated in high concentrations to enhance filtering, then light blocking is improved, but cosmetic defects (haze, yellowness) increase
Solution Approach 1:
By modifying the UV absorber structure with ester groups, the patent changes the concentration parameter at which the absorber functions effectively. The ester-modified compounds achieve optimal UV and blue light filtering at lower concentrations (0.01-5% by weight), preventing cosmetic defects like haze and yellowness that occur at higher concentrations with conventional absorbers.
3Object-affected harmful factors
If conventional benzotriazole UV absorbers are used, then UV protection is achieved, but processing speed and compatibility are reduced
Solution Approach 1:
The introduction of ester groups (such as -COOCH3, -COOC2H5, -COOCH2CH3) into the benzotriazole structure fundamentally changes the solubility and reactivity parameters of the UV absorber. These ester-modified compounds exhibit enhanced compatibility with polymerizable systems and faster processing speeds, reducing manufacturing time while maintaining effective UV protection.
4Object-affected harmful factors
If UV absorbers are added to the formulation, then UV filtering is improved, but compatibility issues and precipitation occur
Solution Approach 1:
The ester group modification changes the polarity and solubility parameters of the benzotriazole UV absorber, enabling it to remain uniformly dissolved in the polymerizable composition throughout the formulation process and during storage. This prevents precipitation and maintains formulation homogeneity while providing effective UV filtering.
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 solution provides a substrate-borne UV and blue light filter that is easy to implement, cost-effective, and results in transparent, colorless optical materials with high blue light cut-off efficiency and improved productivity, ensuring retinal protection without cosmetic defects.
Implementation Method 1
The UV absorber can be incorporated into the finished product through different technologies at different locations, generally in a coating such as a hard coat, but also in the bulk substrate... to reduce or prevent UV light from reaching the retina
Data Source
Figure 1~2
AI summary
Optical material comprising a polymer matrix and at least one benzotriazole compound having at least one ester group, wherein said at least one benzotriazole is a chlorobenzotriazole compound that does not comprise any polymerizable group selected from allylic, acrylic and methacrylic moieties, or the optical transmittance through a 2 mm thick layer of said optical material is lower than 1 % for each light wavelength ranging from 280 to 400 nm, and higher than 65 % for light having a wavelength of 430 nm. This optical material can be used to protect from phototoxic blue light and UV light.