Photocurable Inkjet Ink Composition for Low Migration and Fast Curing
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Solution Overview
Problem
Photocurable inkjet ink compositions with high-molecular-weight photoinitiators face issues of increased viscosity and migration of unreacted initiator components, which affect the processing and safety of printed materials.
Innovation Solution
A photocurable inkjet ink composition containing a polymeric photoinitiator with ethylenic unsaturated bonds, a thioxanthone-based compound, and specific (meth)acrylate-based compounds, adjusted to have a viscosity of 100 cps or less and a surface tension of 32.0 mN/m or less, ensuring high reactivity and reduced migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a low-molecular-weight photoinitiator with high reactivity is used, then quick curing is achieved, but unreacted initiator and initiator fragments migrate from the cured coating film
Solution Approach 1:
The patent changes the molecular weight parameter of the photoinitiator from low to high (polymeric), which reduces reactivity and curing speed but also reduces migration. To compensate for the reduced reactivity, the patent introduces a sensitizer (thioxanthone-based compound) that enhances the photoinitiator's effectiveness, thereby maintaining quick curing while using a high-molecular-weight photoinitiator to prevent migration.
Solution Approach 2:
The patent introduces a sensitizer (thioxanthone-based compound) as an intermediary substance that mediates between the photoinitiator and light energy. The sensitizer absorbs light and transfers energy to the photoinitiator, enabling efficient curing with a polymeric photoinitiator that has lower inherent reactivity but reduced migration potential.
2Object-generated harmful factors
If the molecular weight of the photoinitiator is increased to prevent migration, then migration is reduced, but the viscosity of the composition becomes higher
Solution Approach 1:
The patent carefully controls the molecular weight parameter of the polymeric photoinitiator within a specific range (1,000 to 100,000) to balance two opposing requirements: high enough to prevent migration but low enough to maintain acceptable viscosity. The patent also adjusts the concentration of the polymeric photoinitiator (0.1 to 50% by mass) to optimize the balance between migration prevention and viscosity control.
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 composition achieves high reactivity, excellent antimigration properties, and improved resin film adhesion, making it suitable for food packaging applications with LED curability and reduced odor and discoloration risks.
Implementation Method 1
a thioxanthone-based compound having photosensitization action
Implementation Method 2
A. a polymeric photoinitiator having ethylenic unsaturated bonds... C. a (meth)acrylate-based polymerizable compound
Data Source
AI summary
A photocurable inkjet ink composition containing the following A to E, having a viscosity of 100 cps or less and a surface tension of 32.0 mN/m or less: A. a polymeric photoinitiator having ethylenic unsaturated bonds, B. a thioxanthone-based compound having photosensitization action, C. a (meth)acrylate-based polymer compound, D. a (meth)acrylamide-based compound and/or aminobenzoate compound, and E. a surface additive. The photocurable inkjet ink composition is made to have appropriate viscosity as an inkjet ink composition while also realizing sufficiently high reactivity to reduce migration substances generating from the coating film of the cured photocurable inkjet ink composition.