Phenylglyoxalic Esters for Low-Migratable Photopolymerization
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Solution Overview
Problem
Photopolymerizable systems used in food packaging coatings face challenges with photoinitiators that generate fragments with high migratability, volatility, and odor during photochemical decomposition, particularly aromatic phenylglyoxalic esters which produce irritant and malodorous compounds like benzaldehyde.
Innovation Solution
A restricted family of aromatic phenylglyoxalic esters with specific structural formulas (I) is developed, which upon photochemical decomposition, produce fragments with low migratability, volatility, and odor, and are used in combination with reactive oligomers and monomers for coating applications, including those for food packaging, metal, wood, and plastic surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional aromatic phenylglyoxalic esters are used as photoinitiators, then photopolymerisation can be initiated, but the decomposition products have high migratability, volatility and odour
Solution Approach 1:
The patent modifies the molecular structure of phenylglyoxalic esters by changing parameters such as the ester group (A = O, S, or NR3), alkyl chain lengths (R1 and R2 as C1-C18 alkyl or cycloalkyl), and introducing polyether chains ((CH2CH2O)nR4 where n = 1-6). These parameter changes result in decomposition products that are less migratable and have lower odour while maintaining photoinitiation efficiency
Solution Approach 2:
The patent creates composite molecular structures combining phenylglyoxalic core with modified ester groups and polyether chains. This composite approach allows the photoinitiator to generate decomposition fragments with improved safety profiles (lower migratability and odour) while retaining the necessary photochemical functionality for initiating polymerisation
2Productivity
If photoinitiators with high photochemical reactivity are used, then polymerisation starts efficiently, but toxic and malodorous fragments are generated
Solution Approach 1:
By modifying the ester group A (O, S, NR3) and the R1/R2 substituents (including polyether chains with n = 1-6), the patent achieves a balance where the photoinitiator maintains high photochemical reactivity for efficient polymerisation initiation while producing decomposition fragments with reduced toxicity and irritancy compared to conventional benzaldehyde-based products
Solution Approach 2:
The patent converts the potentially harmful decomposition fragments into beneficial low-migratable, low-odour products by strategic molecular design. The modified phenylglyoxalic esters decompose into fragments that are less harmful to food packaging safety while still allowing efficient photopolymerisation to proceed
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 phenylglyoxalic esters of formula I act as efficient photoinitiators, providing high photochemical reactivity and heat stability, while ensuring low odor and volatility in the resulting polymerized coatings, making them suitable for food packaging and other surface coatings.
Implementation Method 1
by photochemical decomposition, generate fragments having low migratability, volatility and odour
Implementation Method 2
generates radicals that are able to start a polymerisation process
Data Source
AI summary
The present invention concerns photopolymerisable systems comprising reactive oligomers and/or monomers having ethylenically unsaturated groups and at least one phenylglyoxalic ester that, by photochemical decomposition, generates fragments having low migratability and low odour.