Electron Beam-Curable Inkjet Inks for Food Packaging
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Solution Overview
Problem
UV-curing inks used in inkjet technology face issues such as photoinitiator migration, incomplete curing on porous substrates, and the production of undesirable by-products, which are problematic for health-critical applications like food packaging and children's toys, due to their structure and reactivity.
Innovation Solution
Electron-beam-curable inks with a high proportion of reactive diluents and low prepolymers, free of photoinitiators, are used, which are applied via inkjet technology and cured using electron radiation, ensuring complete curing and minimizing by-product formation through precise radiation dose control and solvent evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV-curing inks with photoinitiators are used, then curing speed and process efficiency are improved, but photoinitiator migration and by-product formation occur which are harmful for food packaging applications
Solution Approach 1:
The patent removes photoinitiators from the ink formulation entirely, replacing UV-curing chemistry with electron beam curing chemistry. This extraction of the harmful component (photoinitiator) eliminates migration issues while maintaining curing functionality through alternative chemistry based on compounds with electron beam curing capability.
Solution Approach 2:
The patent changes the curing mechanism from UV-light-initiated photopolymerization to electron beam-induced polymerization. This parameter change in the energy source and chemical reaction pathway eliminates the need for photoinitiators and their associated migration problems, while achieving complete curing.
2Adaptability or versatility
If UV-curing inks are applied to porous substrates, then printing versatility is improved, but incomplete curing occurs leading to by-product formation and odor
Solution Approach 1:
The patent replaces UV light penetration (which cannot penetrate porous substrates effectively) with electron beam radiation that can penetrate and cure ink within porous substrates. This substitution of the energy delivery mechanism ensures complete curing throughout the ink layer regardless of substrate porosity.
Solution Approach 2:
The patent changes the energy penetration characteristics by using electron beams instead of UV light. Electron beams have different penetration and interaction properties that enable complete curing of ink on porous substrates, eliminating incomplete reaction and associated by-products.
3Object-affected harmful factors
If photoinitiators are derivatized to reduce migration, then migration risk is reduced, but reactivity decreases leading to slower process speed
Solution Approach 1:
The patent extracts photoinitiators from the system entirely and replaces them with monomers and oligomers that possess intrinsic electron beam curing capability. This eliminates the need for derivatization compromises and achieves both low migration and high reactivity simultaneously.
Solution Approach 2:
The patent uses composite ink formulations containing multiple compounds with electron beam curing capability, combining monomers and oligomers that work synergistically under electron beam irradiation to achieve complete and rapid curing without migration issues.
4Ease of operation
If inkjet inks with low viscosity are used, then ease of application through inkjet nozzles is improved, but pigment particle size must be reduced which may affect color strength
Solution Approach 1:
The patent changes the chemical composition parameters of the ink to achieve lower viscosity while maintaining pigment stability and color strength. The specific formulation with compounds having electron beam curing capability and appropriate solvent selection optimizes both flow properties for inkjet printing and pigment performance.
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
This approach allows for the production of stable, odorless, and fully cured color layers on various substrates, including porous ones, with reduced migration risks, enabling their safe use in health-critical areas like food packaging and children's toys, while maintaining high printing speeds and image quality.
Implementation Method 1
electron-curable inks... which are applied via inkjet technology and cured using electron radiation
Implementation Method 2
trigger the polymerization reactions of the acrylate oligomers
Implementation Method 3
solvent evaporation... ensuring complete curing and minimizing by-product formation
Data Source
AI summary
The invention relates to electron beam-curable inks which contain 10 to 40% by weight of oligomer, 30 to 89% by weight of reactive diluent and 1 to 15% by weight of pigments, and are free of photoinitiators. The invention likewise relates to a printing method wherein electron beam-curable inks are applied to a substrate surface by means of inkjet technology and then cured by the action of an electron beam. The inventive inks and methods can be used for printing of articles in health-critical areas, such as food and drink packaging and children's toys.