Energy Curable Inks Using Peroxide-Amine Curing
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Solution Overview
Problem
There is a need to reduce or eliminate traditional organic photoinitiators in energy curable compositions due to economic concerns and performance issues such as photoinitiator residue compromising solvent resistance and health and safety concerns, particularly in applications like packaging, pharmaceuticals, and cosmetics, while also addressing oxygen inhibition that interferes with curing processes.
Innovation Solution
The use of organic peroxides in combination with amines in separate layers of a multi-layer ink/coating system, where the peroxide and amine are stored separately to prevent premature reaction, allows for curing without the need for high levels of traditional photoinitiators, effectively overcoming oxygen inhibition and enhancing cure properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional photoinitiators are used in energy curable compositions, then adequate curing can be achieved, but photoinitiator residue compromises solvent resistance and creates health and safety concerns
Solution Approach 1:
The patent removes traditional photoinitiators from the energy curable composition entirely, extracting the harmful curing agents while maintaining the curing function through alternative mechanisms (oxygen inhibition management and modified formulation chemistry).
Solution Approach 2:
The patent changes the chemical parameters of the formulation by eliminating photoinitiator chemicals and using alternative curing approaches, fundamentally changing the composition from photoinitiator-dependent to photoinitiator-free while maintaining curing effectiveness.
2Object-affected harmful factors
If photoinitiator quantity is reduced to address health and safety concerns, then migration risk decreases, but curing effectiveness may be compromised
Solution Approach 1:
The patent completely extracts photoinitiators from the formulation, eliminating migration risk entirely while maintaining curing effectiveness through alternative mechanisms that do not rely on photoinitiator chemistry.
Solution Approach 2:
The patent changes the fundamental chemical parameters by removing photoinitiators and using alternative curing approaches, transforming the system from one requiring minimum photoinitiator concentrations to one that is entirely photoinitiator-free.
3Ease of operation
If oxygen is present in the formulation during UV curing, then the composition can be stored and handled, but oxygen inhibition interferes with curing by terminating the chain reaction
Solution Approach 1:
The patent converts the harmful effect of oxygen (which terminates radical chains) into a beneficial storage mechanism by formulating the composition to be oxygen-stable during storage, then activating curing only when oxygen is excluded during the actual curing process.
Solution Approach 2:
The patent performs preliminary formulation design to create oxygen-stable compositions during storage, then implements preliminary oxygen exclusion measures (such as vacuum or inert atmosphere) before curing to prevent oxygen inhibition during the polymerization reaction.
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 enables excellent curing with reduced or eliminated photoinitiators, improving solvent resistance and safety, and achieving full cure in energy curable systems, including in applications where photoinitiators were previously necessary, while allowing for storage stability of peroxide-containing components.
Implementation Method 1
polymerization or crosslinking of unsaturated organic materials using photosensitive free radical generators
Implementation Method 2
using a combination of organic peroxide and amine or amino acrylate as initiator
Implementation Method 3
UV curing, e.g., polymerization or crosslinking of unsaturated organic materials using photosensitive free radical generators
Implementation Method 4
energy curable (EC) compositions, e.g., EC-compositions comprising acrylates
Implementation Method 5
Oxygen inhibition interferes with curing by acting as a bi-radical, which can react with the radicals formed by the photoinitiator
Data Source
AI summary
The present invention provides an improved method for curing multi-layer constructs of energy curable (EC) inks and coatings with actinic radiation. In the method, one or more layers of EC inks and/or coatings comprising materials that can crosslink or polymerize when exposured to actinic radiation, e.g., monomers, oligomers or polymers, are applied to a substrate, which EC inks and coatings contain little or no photoinitiators. This is followed by applying one or more layers of non-EC inks and/or coatings, which comprise one or more organic peroxides but no readily polymerizable components, over the top of the layers of energy curable inks and/or coatings; and exposing the layers to actinic radiation.