Ink Set Uniform Curability via Localized Initiator Composition
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Solution Overview
Problem
Conventional ink sets face challenges in achieving uniform curability among different colors, leading to variations in glossiness and adhesiveness, with some inks being insufficiently cured or excessively cured, resulting in sticky or peeled-off images.
Innovation Solution
An ink set comprising ink A with a phthalocyanine or quinacridone colorant and a hydrogen abstraction photopolymerization initiator, and ink B without these structures, where ink B contains a limited amount of hydrogen abstraction photopolymerization initiator, allowing for homogeneous curing under the same conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ink sets use the same photopolymerization initiator composition for all colors, then the curing process is simplified, but uniform curability and glossiness cannot be achieved across different colors
Solution Approach 1:
The patent applies local quality by using different photopolymerization initiator compositions tailored to specific color requirements. Ink A (containing phthalocyanine or quinacridone) uses a hydrogen abstraction type initiator, while Ink B (other colors) uses a different initiator composition. This localized differentiation ensures each color achieves optimal curability and glossiness under the same irradiation conditions.
Solution Approach 2:
The patent changes the chemical parameters of the photopolymerization initiators based on color type. By selecting initiators with different molecular structures and reactivity characteristics appropriate for each ink formulation, the system achieves uniform curing performance across all colors without requiring different irradiation doses.
2Reliability
If high amounts of actinic radiation are used to ensure sufficient curing, then curability improves, but gel crystal melting occurs and glossiness deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters of the photopolymerization initiators to achieve high curing efficiency at lower radiation doses. The hydrogen abstraction type initiator in Ink A and the alternative initiator in Ink B are selected to maximize radical generation efficiency, enabling complete curing with minimal actinic radiation exposure and associated thermal effects.
3Temperature
If low amounts of actinic radiation are used, then gel crystal stability is maintained, but insufficient curing occurs leading to sticky or peeled-off images
Solution Approach 1:
The patent addresses this contradiction by locally optimizing initiator composition for each color type. The hydrogen abstraction type initiator in Ink A and the alternative initiator in Ink B are specifically selected to achieve maximum curing efficiency at low radiation doses, ensuring complete polymerization without requiring high energy input that would melt gel crystals.
Solution Approach 2:
By changing the chemical structure and reactivity parameters of the photopolymerization initiators, the system achieves high curing efficiency at low radiation doses. The initiators are selected to have optimal absorption characteristics and radical generation efficiency, enabling complete curing with minimal actinic radiation exposure.
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 set ensures uniform glossiness and high adhesiveness across all colors, preventing sticky or peeled portions, and allows for sufficient curing with a smaller amount of actinic radiation.
Implementation Method 1
each of the ink compositions comprises a photocurable compound and a photopolymerization initiator... is cured through irradiation with actinic radiation
Data Source
AI summary
The present invention provides: an ink set in which all the inks have satisfactory curability and all the inks can be evenly cured under the same curing conditions; and an image forming method which comprises using the ink set. The ink set comprises ink A and ink B, which each comprise a photopolymerizable compound, a photopolymerization initiator, a gellant, and a colorant and cure upon irradiation with actinic rays. The ink A is a composition in which the colorant has a phthalocyanine structure or quinacridone structure and the photopolymerization initiator comprises a photopolymerization initiator of a hydrogen abstraction type. The ink B is a composition in which the colorant has neither a phthalocyanine structure nor a quinacridone structure and the content of a photopolymerization initiator of a hydrogen abstraction type is less than 0.1 mass% with respect to the total mass of the ink B.