UV Curable Ink Composition Using Hindered Amine Mediator
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Solution Overview
Problem
Existing UV curable ink jet recording inks face issues with curability, storage stability, and ejection stability, particularly when using thioxanthone-based photopolymerization initiators, which are affected by dissolved oxygen levels and lead to inferior performance.
Innovation Solution
A UV curable ink jet recording ink composition containing a thioxanthone-based photopolymerization initiator and a hindered amine compound, with a dissolved oxygen content of 20 ppm or less, to enhance curability, storage stability, and ejection stability, and an ink container with a low oxygen permeation rate to maintain these properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dissolved oxygen content is reduced to improve ejection stability, then ejection stability is improved, but storage stability deteriorates because oxygen cannot sufficiently inhibit polymerization
Solution Approach 1:
A hindered amine compound is introduced as an intermediary substance to replace dissolved oxygen in the polymerization inhibition function. The hindered amine compound specifically scavenges free radicals generated during dark polymerization, thereby maintaining storage stability without relying on dissolved oxygen, which is needed for ejection stability.
Solution Approach 2:
The chemical composition parameters of the ink are changed by adding a hindered amine compound with specific molecular structure and concentration. This parameter change enables the system to achieve both low dissolved oxygen content (for ejection stability) and effective polymerization inhibition (for storage stability) through the new chemical component.
2Ease of manufacture
If thioxanthone-based photopolymerization initiator is used to improve solubility and cost, then solubility and cost are improved, but ejection stability deteriorates when dissolved oxygen content is high
Solution Approach 1:
The hindered amine compound acts as a mediator that enables the use of thioxanthone-based photopolymerization initiator by compensating for the initiator's tendency to cause ejection instability at high dissolved oxygen levels. The hindered amine compound controls the polymerization reaction more effectively, ensuring stable ejection performance.
3Stability of the object's composition
If dissolved oxygen is increased to inhibit polymerization and improve storage stability, then storage stability is improved, but ejection stability deteriorates due to air bubble formation
Solution Approach 1:
The hindered amine compound serves as a superior intermediary that provides polymerization inhibition without the harmful side effect of air bubble formation. Unlike dissolved oxygen which forms bubbles during ejection, the hindered amine compound inhibits polymerization through chemical radical scavenging, maintaining both storage and ejection stability.
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 ink composition exhibits improved curability, storage stability, and ejection stability, ensuring stable ink ejection and long-term storage without significant viscosity changes, while maintaining low dissolved oxygen levels.
Implementation Method 1
UV curable ink jet recording inks that can be cured by being irradiated with UV radiation
Implementation Method 2
an ink composition further containing a hindered amine polymerization inhibitor can be stably stored
Data Source
AI summary
The UV curable ink jet recording ink composition contains a thioxanthone-based photopolymerization initiator and a hindered amine compound. The dissolved oxygen content in the ink composition is 20 ppm or less.