Fluorene Sulfonium Photoinitiator for Red-Shifted Absorption
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Solution Overview
Problem
Current cationic photoinitiators, such as triarylsulfonium salts, have limitations in absorption wavelength, solubility, and yellowing resistance, which restrict their industrial application and initiation efficiency.
Innovation Solution
A novel cationic photoinitiator with a sulfonium salt structure incorporating a fluorene core, which exhibits a red shift in absorption wavelength and improved yellowing resistance, is developed, represented by the general formula (I), allowing for enhanced photosensitivity and solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If triarylsulfonium salts are used as cationic photoinitiators, then initiation activity and thermal stability are improved, but absorption wavelength remains less than 300nm and yellowing resistance is poor
Solution Approach 1:
The patent changes the chemical structure parameters of the photoinitiator by introducing fluorene core structures with specific substituents (R1-R7 groups) to achieve both red-shifted absorption wavelength and improved yellowing resistance while maintaining initiation activity
Solution Approach 2:
The patent creates a composite molecular structure combining sulfonium salt functionality with fluorene core structure, achieving synergistic effects that simultaneously improve absorption properties, yellowing resistance, and initiation efficiency
2Ease of operation
If long-chain alkyl groups are introduced to improve solubility, then solubility is improved, but migration resistance decreases and micromolecular compounds are generated
Solution Approach 1:
The patent applies local quality by introducing moderate-length alkyl groups (C1-C10) at specific positions on the fluorene structure, providing sufficient solubility improvement without excessive chain length that would cause migration and micromolecular compound formation
3Power
If multifunctional groups are introduced to improve initiation efficiency, then initiation efficiency is improved, but structural complexity increases and yellowing resistance deteriorates
Solution Approach 1:
The patent introduces multifunctional groups (hydroxyl, cyano, nitro, carbonyl, carboxyl) at specific local positions on the fluorene structure, achieving improved initiation efficiency while controlling the overall molecular structure to maintain yellowing resistance
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 new photoinitiator demonstrates improved photosensitivity, low migration, and excellent yellowing resistance, with pencil hardness exceeding 2H and better storage stability compared to conventional sulfonium salt photoinitiators.
Implementation Method 1
A photoinitiator is a key component of a photocurable product and has a dominating effect on the cure rate of the photocurable product. According to different mechanisms of initiation, photoinitiators may be divided into cationic photoinitiators and radical photoinitiators.
Implementation Method 2
It has been found in studies that the photoinitiator obtained by incorporating a sulfonium salt structure and a fluorene structure as described below has a red shift of absorption wavelength and an outstanding photosensitive property
Data Source
AI summary
This invention discloses a novel cationic photoinitiator and a preparation method and use thereof. The cationic photoinitiator has a structure as represented by general formula (I) below. It can match a longer absorption wavelength in the process of application and has an outstanding photosensitive property, and has characteristics of no proneness to migration and good yellowing resistance.