Wet-Trapping Ink Layers for Reduced Photoinitiator Residue
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Solution Overview
Problem
Current methods for printing multiple layers of inks and coatings on substrates require high levels of photoinitiators, which can lead to residue issues, contamination, and increased costs, while existing self-initiating systems fail to achieve necessary resistance properties.
Innovation Solution
A wet-trapping method where radiation-curable ink or coating layers containing photoinitiators are applied alongside layers without photoinitiators, allowing for simultaneous curing at the end of the print run, leveraging free radicals generated in adjacent layers to cure intermediate layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of photoinitiators are used in each ink layer, then complete curing of each layer is achieved, but residue contamination and cost increase
Solution Approach 1:
The patent extracts the photoinitiator from intermediate ink layers, removing the harmful component while maintaining curing functionality through a single photoinitiator-containing layer combined with electron beam energy
Solution Approach 2:
The patent changes the curing parameter from UV light activation to electron beam activation, allowing curing without photoinitiators in intermediate layers. This parameter change enables the same curing function with reduced harmful residues
2Reliability
If multiple UV lamps are used to cure each layer, then complete curing is achieved, but energy consumption and equipment complexity increase
Solution Approach 1:
The patent merges multiple curing operations into a single electron beam curing step that cures all ink layers simultaneously, eliminating the need for multiple UV lamps and reducing energy consumption
Solution Approach 2:
The patent replaces the mechanical UV lamp system with an electron beam system, achieving curing through electron beam energy rather than electromagnetic radiation, which reduces the number of energy sources required
3Object-generated harmful factors
If photoinitiator-free inks are used, then residue is minimized, but curing capability is lost
Solution Approach 1:
The patent introduces electron beam energy as an intermediary that enables curing of photoinitiator-free inks. The electron beam acts as a mediator that provides the activation energy needed for curing without requiring photoinitiator chemicals
Solution Approach 2:
The patent changes the activation parameter from photoinitiator-based UV curing to electron beam-based curing, enabling photoinitiator-free inks to achieve complete curing through alternative energy activation
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 method reduces the overall photoinitiator load, minimizes residue, enhances solvent resistance, and allows for a more efficient curing process, particularly for difficult-to-cure colors like white and black, while also reducing the number of UV lamps needed.
Implementation Method 1
radiation-curable ink or coating layers (A) containing one or more photoinitiators... curing all coating and/or ink layers simultaneously at the end of the print run
Implementation Method 2
leveraging free radicals generated in adjacent layers to cure intermediate layers
Data Source
AI summary
The present invention provides a method for applying multiple ink and/or coating layers on a substrate. At least one of the ink and/or coating layers contains one or more photoinitiators, and at least one of the ink and/or coating layers does not contain any photoinitiators. In certain embodiments, all of the ink and/or coating layers are wet trapped and the entire print construct is cured by exposure to UV radiation after all of the ink and/or coating layers have been applied. In certain embodiments, the wet trapping method of the present invention can be used to prepare laminates.