Water-Based Ink Set Bleeding Prevention via Conductivity Control
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Solution Overview
Problem
Ink-jet recording technologies face issues with bleeding at the boundary between black and color recording portions, and the formation of pigment aggregations or coagulations, which affect recording quality and maintenance efficiency due to the insolubility of pigments in water-based ink sets.
Innovation Solution
A water-based ink set comprising a black ink with self-dispersible pigments and water-soluble organic solvents of low vapor pressure, combined with color inks containing resin dispersants, where the blending amounts of solvents and electric conductivity are optimized to prevent aggregation and bleeding, satisfying specific conductivity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water-based pigment inks are used for ink-jet recording, then recording quality is improved, but bleeding occurs at the boundary between black and color recording portions
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by specifying precise ranges for water-soluble organic solvent content (15-35% by weight average), electric conductivity relationships (C-K≧0.6 and A≦1.5), and pigment concentration. These parameter adjustments prevent bleeding while maintaining recording quality by optimizing the interaction between black and color inks.
Solution Approach 2:
The patent employs composite ink formulations combining water-based pigments with specific ratios of water-soluble organic solvents and resin dispersants. This composite approach creates an ink system where the solvent and dispersant work synergistically to prevent pigment aggregation and bleeding, while maintaining the water-based eco-friendly nature of the ink.
2Manufacturing precision
If water-based pigment inks are used for ink-jet recording, then recording quality is improved, but pigment aggregation occurs during maintenance
Solution Approach 1:
The patent optimizes the electric conductivity parameters and organic solvent content to prevent pigment aggregation during maintenance operations. The specific conductivity relationships (C-K≧0.6 and A≦1.5) ensure that pigments remain dispersed even when inks mix during wiping operations, maintaining jetting stability throughout the printer's operational life.
Solution Approach 2:
The patent introduces resin dispersants as intermediary substances that mediate between the water-based solvent and pigment particles. These dispersants create a stable interface that prevents pigment aggregation during maintenance, allowing easy wiping and cleaning without forming difficult-to-remove aggregates.
3Reliability
If water-soluble organic solvent content is increased to prevent pigment aggregation, then jetting stability is improved, but bleeding between black and color portions occurs
Solution Approach 1:
The patent precisely balances the water-soluble organic solvent content within 15-35% by weight average range and establishes specific electric conductivity relationships. This balanced parameter selection achieves jetting stability by preventing pigment aggregation while simultaneously preventing bleeding by controlling the ink's interaction with the recording medium and other inks.
Solution Approach 2:
The patent applies different functional requirements to different aspects of the ink system: higher solvent content and specific dispersants are optimized for preventing aggregation in the color inks, while the black ink is optimized with complementary parameters to prevent bleeding. This localized optimization of ink properties for different functions resolves the contradiction between jetting stability and bleeding prevention.
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 solution effectively prevents bleeding between black and color recording portions and reduces pigment aggregation during maintenance, enhancing the stability and maintainability of ink-jet recording systems.
Implementation Method 1
a water-based black ink containing a self-dispersible pigment, a water-soluble organic solvent of which vapor pressure is less than 1 Pa, and water
Implementation Method 2
condition X: C−K≧0.6... condition Y: A≦1.5... the relation between the electric conductivity of the water-based black ink containing the self-dispersible pigment and the electric conductivity of the water-based color inks
Data Source
AI summary
There is provided a water-based ink set for ink-jet recording, including: a water-based black ink containing a self-dispersible pigment, a water-soluble organic solvent of which vapor pressure is less than 1 Pa, and water; water-based color inks of two or more colors each containing a color pigment, a resin dispersant, a water-soluble organic solvent of which vapor pressure is less than 1 Pa, and water, wherein an average value of blending amounts of the water-soluble organic solvents in all of the water-based inks constituting the water-based ink set is in a range of 15% by weight to 35% by weight, and the water-based ink set satisfies the following condition X and condition Y,condition X: C−K≧0.6condition Y: A≦1.5.