Aqueous Ink Core-Shell Resin Particles for Fluorescent Color Stability
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Solution Overview
Problem
The printing industry faces challenges in achieving excellent color developability and productivity when using fluorescent colors, particularly with ink jet systems, due to limitations in ink properties such as viscosity and the physical properties of fluorescent dyes and resins, which restrict the amount of fluorescent material that can be added to the ink, leading to issues with ejection stability and sticking recoverability.
Innovation Solution
An aqueous ink is developed that includes resin particles dyed with fluorescent dyes, featuring a core-shell structure with an aromatic group-containing unit and anionic group-containing unit, and a water-soluble resin with specific acid value and crosslinking agent content, enhancing color developability, ejection stability, and sticking recoverability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a sufficient amount of fluorescent coloring material is added to the ink to achieve excellent color developability, then the color developability is improved, but the physical properties of the ink such as viscosity are deteriorated, leading to poor ejection stability
Solution Approach 1:
The patent introduces resin particles as an intermediary carrier to hold the fluorescent coloring material. The resin particles have a core-shell structure where the core contains the fluorescent dye and the shell provides compatibility with the aqueous ink medium. This mediator allows high concentration of fluorescent material to be added without directly deteriorating the ink's physical properties, thus maintaining ejection stability while achieving excellent color developability
Solution Approach 2:
The patent changes the physical state of the fluorescent coloring material from dissolved/dispersed form to particle-bound form. By incorporating the fluorescent dye into resin particles with specific size distribution (0.01-10 μm), the ink's viscosity and surface tension parameters are maintained within optimal ranges for ink jet ejection, while still achieving high color developability through sufficient fluorescent material content
2Quantity of substance
If a sufficient amount of fluorescent coloring material is added to the ink to achieve excellent color developability, then the color developability is improved, but the sticking recoverability is deteriorated
Solution Approach 1:
The resin particles act as a mediator that prevents direct interaction between the fluorescent coloring material and the ink jet system components. The shell portion of the resin particles, containing specific functional groups, provides steric hindrance and electrostatic repulsion that prevents the fluorescent material from adhering to the nozzle and other components, thereby maintaining sticking recoverability even with high fluorescent material content
Solution Approach 2:
The patent modifies the surface properties of the fluorescent coloring material by encapsulating it within resin particles. This changes the surface charge and hydrophilicity parameters, preventing the fluorescent material from causing nozzle clogging and maintaining sticking recoverability while allowing sufficient fluorescent material to be added for excellent color developability
3Quantity of substance
If offset printing is used to record fluorescent images with excellent color developability, then the color developability is improved, but the productivity is deteriorated due to repeated over-printing
Solution Approach 1:
The patent replaces the mechanical over-printing process of offset printing with a digital ink jet system. The aqueous ink containing resin particles with fluorescent coloring material can be ejected directly in a single pass, achieving excellent color developability without the need for repeated printing. This substitution of printing mechanism dramatically improves productivity while maintaining color quality
4Quantity of substance
If electrophotographic system is used to record images with highly vivid colors, then the color developability is improved, but the adaptability to recording medium is deteriorated
Solution Approach 1:
The patent uses an ink jet system that ejects aqueous ink containing resin particles through pneumatic or thermal mechanisms. This non-contact ejection method allows the ink to be deposited on various recording media including textiles, large area materials, and thick materials that are incompatible with electrophotographic systems. The resin particle formulation ensures good adhesion and color development across different media types, achieving both high color intensity and broad adaptability
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 aqueous ink achieves excellent color developability, improved ejection stability, and enhanced sticking recoverability, allowing for the production of vivid fluorescent images while maintaining ink jet system performance.
Implementation Method 1
fluorescent dye containing a fluorescence-emitting dye
Data Source
AI summary
The aqueous ink for ink jet contains a resin particle dyed with a fluorescent dye, and a water-soluble resin. The fluorescent dye contains a fluorescence-emitting dye selected from the group consisting of basic dye, disperse dye and oil-soluble dye, the resin particle has a core portion that contains an aromatic group-containing unit and cyano group-containing unit, and a shell portion that contains an aromatic group-containing unit, an anionic group-containing unit and a crosslinking agent-derived unit, but free of cyano group-containing unit, percentage (% by mass) of the crosslinking agent-derived unit in the shell portion is 30% by mass or more to 80% by mass or less, the water-soluble resin having an aromatic group-containing unit and an anionic group-containing unit, and the water-soluble resin having an acid value of 100 mgKOH/g or more to 180 mgKOH/g or less.