Ink Pack Nitroxyl Radical Inhibitor Suppresses Dark Polymerization
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Solution Overview
Problem
Ultraviolet curable inkjet ink compositions face issues with dark polymerization and deteriorated character reproducibility when sealed in ink packs, particularly when aluminum or aluminum alloy layers are used, leading to changes in ink viscosity and reduced printing quality.
Innovation Solution
An ink pack design that incorporates an ultraviolet curable ink composition with a specific range of nitroxyl radicals (1.2×10^16 to 3.0×10^19 spins per milliliter), including 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl and acyl phosphine-based photopolymerization initiators, sealed in a laminate structure with aluminum and plastic layers, which helps maintain excellent curability and character reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultraviolet curable ink composition is sealed in ink pack with aluminum or aluminum alloy layers, then the ink pack provides good barrier properties and protection, but dark polymerization occurs and character reproducibility deteriorates
Solution Approach 1:
The patent introduces an intermediary substance (polymerization inhibitor) between the ink composition and the aluminum layer to prevent the harmful interaction. The inhibitor acts as a mediator that stops the dark polymerization reaction initiated by the aluminum layer, thereby preserving character reproducibility while maintaining the barrier properties of the aluminum packaging.
Solution Approach 2:
The patent converts the harmful effect of the aluminum layer (which initiates dark polymerization) into a beneficial outcome by adding a polymerization inhibitor. The inhibitor transforms the potentially harmful interaction into a controlled system where the aluminum layer's barrier properties are retained while its harmful polymerization-inducing effect is neutralized, ensuring both protection and print quality.
2Stability of the object's composition
If ultraviolet curable ink composition is stored in sealed ink pack, then storage stability should be improved, but dark polymerization occurs during storage causing viscosity changes
Solution Approach 1:
The patent applies preliminary action by incorporating a polymerization inhibitor into the ink composition before storage. This preventive measure is taken in advance to stop dark polymerization from occurring during the storage period, thereby maintaining composition stability throughout the intended storage duration without requiring special storage conditions.
3Object-affected harmful factors
If aluminum layer is used in ink pack for oxygen barrier, then oxygen impermeability is achieved, but nitroxyl radical concentration changes affecting ink quality
Solution Approach 1:
The polymerization inhibitor serves as an intermediary that protects the nitroxyl radical concentration from changing due to interactions with the aluminum layer. By placing the inhibitor in the ink composition, it mediates between the oxygen-barrier aluminum packaging and the ink components, preventing the aluminum from causing unwanted changes in radical concentration and thus maintaining ink quality.
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 pack effectively suppresses dark polymerization and maintains superior curability and character reproducibility over time, even when exposed to conditions that might otherwise cause ink quality deterioration.
Implementation Method 1
an ultraviolet curable type inkjet ink composition which contains 4-hydioxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl and has 1.2×10^16 to 3.0×10^19 spins of nitroxyl radicals in one milliliter
Implementation Method 2
the ink composition includes an acyl phosphine-based photopolymerization initiator
Data Source
Figure 1
AI summary
An ink pack is a laminate pack which at least one layer of an aluminum layer or an aluminum alloy layer and at least one layer of a plastic layer are laminated. An ultraviolet curable type inkjet ink composition which contains a compound having a nitroxyl radical, and has 1.2×1016 to 3.0×1019 of the spin number of the nitroxyl radical in one milliliter of the ink composition, is sealed in the ink pack.