UV-Curable Ink Aldehyde Reduction via Acid Additives
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current UV-curable ink and coating compositions using acylphosphine oxide photoinitiators face challenges with high levels of migratable decomposition products, particularly aldehydes, which limit their application in low migration printing and coating, especially in food packaging where contamination risks are high.
Innovation Solution
Incorporating acids, such as organic or inorganic acids generated by photo-acid generators, into the UV-curable compositions to reduce the production of aldehydes like mesitaldehyde during the curing process, thereby minimizing contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acylphosphine oxide photoinitiators are used in UV-curable compositions, then curing efficiency is improved, but aldehyde decomposition products are generated causing migration and contamination
Solution Approach 1:
The patent applies this principle by using the acylphosphine oxide photoinitiator's inherent photodecomposition reaction to generate carboxylic acid as a beneficial byproduct. This carboxylic acid then acts to suppress further aldehyde formation and migration, effectively converting the harmful photodecomposition into a beneficial self-regulating system that maintains low migration levels while preserving high curing efficiency.
2Ease of operation
If high amounts of monofunctional monomers are used in UV-curable compositions, then ease of application is improved, but residual monomers remain after curing causing migration and contamination
Solution Approach 1:
The patent applies this principle by changing the functional parameter of the monomer from monofunctional to polyfunctional. This parameter change increases crosslinking density and cure completeness, thereby reducing residual monomers and their migration potential, while still maintaining ease of application through the UV-curable system.
3Reliability
If acylphosphine oxide and ketosulphone photoinitiators are used together, then curing performance is improved, but detrimental effects on composition stability occur
Solution Approach 1:
The patent applies this principle by extracting the ketosulphone photinitiator from the composition while retaining the acylphosphine oxide photoinitiator. The acylphosphine oxide alone provides sufficient curing performance and has the additional benefit of generating carboxylic acid that suppresses aldehyde migration, thereby eliminating the stability issues associated with ketosulphone while maintaining curing effectiveness.
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 incorporation of acids significantly reduces the amount of aldehydes produced by acylphosphine oxide photoinitiators, enhancing the suitability of these compositions for low migration applications by minimizing contamination risks and allowing increased concentrations of acylphosphine oxide photoinitiators, thus improving their use in sensitive printing and coating processes.
Implementation Method 1
the production of photodecomposition products from the photoinitiator, and especially aldehydes
Implementation Method 2
the amount of aldehyde produced by an acylphosphine oxide during UV-cure of the ink or coating compositions is reduced by incorporation of an acid into the compositions
Implementation Method 3
UV-curable ink and coating compositions
Data Source
AI summary
The present invention is drawn to UV-curable ink and coating compositions comprising acylphosphine oxide photoinitiators and acids. The acids may be inorganic or organic acids, or acids generated by a photoacid generator during UV-cure. Incorporation of the acids into the UV-curable ink and coating compositions results in a reduction of migratable aldehydes that are produced by acylphosphine oxide photoinitiators during UV-cure. The ink and coating compositions are particularly useful for use in applications N that require low migration of low molecular weight materials, such as, for example, food packaging.