Functionalized Benzophenone Photoinitiators for Low Migration Coatings
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Solution Overview
Problem
Current photoinitiators for photo-curable coatings face challenges such as high volatility, odour, migration, and yellowing, poor solubility, and reduced reactivity, making them unsuitable for modern packaging and food-contact applications, and existing solutions like benzophenone derivatives have inefficiencies in synthesis and compatibility issues.
Innovation Solution
Development of novel mixtures of compounds with specific functional groups and ethylene oxide or propylene oxide additions, which form low-viscosity, highly compatible photoinitiators that can be easily processed and integrated into photo-curable compositions, reducing migration and odour while maintaining reactivity and curing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If benzophenone is used as photoinitiator, then fast curing and good solubility are achieved, but high extractability, migration, and strong odour occur
Solution Approach 1:
The patent combines benzophenone with polyether backbones to create composite photoinitiator molecules that integrate the fast-curing capability of benzophenone with the low migration and extractability characteristics of polyether structures. This composite approach allows simultaneous achievement of fast curing and reduced harmful extraction/migration behaviors.
Solution Approach 2:
The patent modifies the molecular parameters of benzophenone by adding polyether chains of specific lengths and compositions, changing the physical and chemical properties to reduce volatility, extractability, and migration while maintaining photoinitiator activity. The polyether chain length and structure are optimized to balance curing performance with reduced harmful effects.
2Object-generated harmful factors
If functionalized benzophenones such as benzophenone-2-methyl ester or acrylated benzophenone are used, then volatility and odour are reduced, but photoinitiator activity is significantly lower
Solution Approach 1:
The patent optimizes the parameters of functionalized benzophenones by selecting specific polyether chain lengths and compositions that minimize steric hindrance and electronic effects on the carbonyl group, thereby maintaining high photoinitiator activity. The polyether chains are designed to reduce volatility and odour while keeping the benzophenone core accessible for efficient photo-curing reactions.
3Use of energy by moving object
If 4-hydroxybenzophenone is used, then absorption maximum is suitable for UV curing, but solubility in UV curable formulations is poor and reactivity is lower
Solution Approach 1:
The patent creates composite structures by attaching polyether chains to 4-hydroxybenzophenone, combining the favorable UV absorption characteristics of the benzophenone core with the excellent solubility and reactivity enhancement provided by the polyether side chains. This composite structure resolves the solubility and reactivity issues while preserving the appropriate absorption maximum.
4Object-generated harmful factors
If poly butandiol ether backbone benzophenone derivatives are synthesized, then odour and migration are reduced, but synthesis requires several tedious steps and products are highly viscous
Solution Approach 1:
The patent optimizes the polyether backbone parameters, selecting specific chain lengths and structures that reduce viscosity to acceptable levels while maintaining low odour and migration. The parameter optimization includes choosing appropriate polyether chain lengths that balance viscosity reduction with continued effectiveness in reducing harmful extraction and migration behaviors.
5Object-generated harmful factors
If carboxy substituted benzophenone derivatives are bound to polyethylene glycol, then migration and odour are reduced, but reactivity is reduced
Solution Approach 1:
The patent modifies the chemical parameters of carboxy substituted benzophenone derivatives by optimizing the polyethylene glycol chain length and structure to minimize steric and electronic effects that reduce reactivity. The parameters are tuned to maintain low migration and odour while preserving adequate photoinitiator reactivity for efficient curing.
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 photoinitiator mixtures exhibit improved solubility, reactivity, and reduced migration and odour, enabling efficient and stable performance in photo-curable coatings, particularly in food-contact applications, with enhanced processing and long-term stability.
Implementation Method 1
Photoinitiators used in photo-curable compositions such as coating compositions need to ensure good cure speed
Implementation Method 2
Another material that has an absorption maximum making it in principle useful to be utilized as photoinitiator is 4-hydroxybenzophenone
Data Source
AI summary
The present invention relates to novel compounds which are useful as functionalized photoinitiators which may be used directly or after further functionalization in various photo-curable coating compositions, including varnishes, lacquers, printing inks and the like, especially varnishes as well as to a process to prepare such novel compounds. The invention also provides radiation-curable surface coating compositions which include at least one of the compounds of the present invention as a photoinitiator. These compounds are especially suitable for radiation curable formulations which are intended for applications where low extracables or leachables are preferred such as printing inks for food packaging.