Water-Based Ink Redispersibility and Bleeding Control
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Solution Overview
Problem
Conventional water-based inks for ink-jet printing on low-liquid absorbing printing media face issues with clogging of nozzles due to flocculated viscous materials, poor drying properties, and color bleeding, leading to deterioration in print quality.
Innovation Solution
A water-based ink formulation containing a pigment, a polymer dispersant, and a water-soluble organic solvent, where the solvent consists of alkanediol, dipropylene glycol, and 2-pyrrolidone in specific amounts, enhancing redispersibility and preventing bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional water-based ink is used for ink-jet printing on low-liquid absorbing printing medium, then the ink can be easily applied, but the ink causes nozzle clogging due to flocculated viscous materials and poor drying properties
Solution Approach 1:
The patent changes the chemical composition parameters of the water-based ink by introducing a specific polymer dispersant with controlled molecular weight (1,000-1,000,000) and specific functional groups (carboxyl, hydroxyl, or amine groups). This parameter change modifies the ink's viscosity, surface tension, and interaction with the printing medium, preventing flocculation and nozzle clogging while maintaining ease of application.
Solution Approach 2:
The polymer dispersant acts as an intermediary substance between the ink components and the printing medium. It mediates the interaction by providing steric hindrance and electrostatic repulsion that prevents pigment aggregation and viscous material flocculation, thereby preventing nozzle clogging while allowing smooth ink flow and application.
2Ease of operation
If conventional water-based ink is used for ink-jet printing on low-liquid absorbing printing medium, then the ink can be easily applied, but the ink exhibits poor drying properties and causes color bleeding
Solution Approach 1:
The patent modifies the ink's physical and chemical parameters by incorporating the specific polymer dispersant, which changes the ink's drying characteristics and surface tension. This enables the ink to dry properly on low-liquid absorbing media without bleeding, while maintaining ease of application through the dispersant's compatibility with water-based formulations.
Solution Approach 2:
The polymer dispersant serves as a mediator that controls the interaction between the ink and the printing medium. It prevents excessive adhesion and bleeding by providing a balanced interface that allows controlled drying, thereby improving print quality while preserving ease of application.
3Stability of the object's composition
If organic solvent-based ink is used for gravure printing on soft packaging, then the pigment disperses well, but the ink poses burden on working environments
Solution Approach 1:
The patent changes the solvent system from organic to water-based by introducing a specific polymer dispersant that is compatible with water. This parameter change maintains effective pigment dispersion through the dispersant's steric and electrostatic mechanisms while eliminating the environmental hazards associated with organic solvents.
Solution Approach 2:
The polymer dispersant acts as an intermediary that enables water-based pigment dispersion, replacing the need for organic solvents. It provides the necessary stabilization and dispersion functions that were previously achieved only through organic solvent systems, thereby eliminating environmental burden while maintaining pigment dispersion 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 exhibits excellent redispersibility and prevents bleeding in printed characters or images, addressing nozzle clogging and drying issues, and maintaining print quality on low-liquid absorbing media.
Implementation Method 1
a water-soluble organic solvent, wherein the water-soluble organic solvent contains at least one organic solvent selected from the group consisting of an alkanediol having not less than 4 and not more than 6 carbon atoms which contains a hydroxy group at both terminal ends thereof, dipropylene glycol and 2-pyrrolidone
Implementation Method 2
containing a pigment, a polymer dispersant, a water-soluble organic solvent and water
Implementation Method 3
the polymer dispersant is such a block copolymer that a difference between an amine value and an acid value thereof is more than 0
Implementation Method 4
In ink-jet printing methods, droplets of ink are directly ejected from very fine nozzles and allowed to adhere to a printing medium
Implementation Method 5
the water-soluble organic solvent contains at least one organic solvent selected from the group consisting of an alkanediol having not less than 4 and not more than 6 carbon atoms which contains a hydroxy group at both terminal ends thereof, dipropylene glycol and 2-pyrrolidone
Data Source
Figure 1
AI summary
The present invention relates to a water-based ink for ink-jet printing on a low-liquid absorbing printing medium, containing a pigment, a polymer dispersant, a water-soluble organic solvent and water, in which the water-soluble organic solvent contains at least one organic solvent selected from the group consisting of an alkanediol having not less than 4 and not more than 6 carbon atoms which contains a hydroxy group at both terminal ends thereof, dipropylene glycol and 2-pyrrolidone in an amount of not less than 85% by mass, and [2] an ink-jet printing method including the step of printing characters or images on a low-liquid absorbing printing medium using the aforementioned ink. The water-based ink for ink-jet printing according to the present invention is excellent in redispersibility as well as can be prevented from suffering from bleeding in the resulting printed characters or images.