Ink Set Surface Tension Control for Bleeding Prevention
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Solution Overview
Problem
Current inkjet recording methods face challenges in producing high-speed, high-resolution color images with minimal bleeding at color boundaries on regular paper with poor ink absorbability or without an aqueous ink-receiving layer, particularly when using inks with high pigment concentration or solid content.
Innovation Solution
An ink set comprising two aqueous inks with different colors, where one ink contains a water-dispersible colorant without a surfactant-based dispersant and the other contains a surfactant-based dispersant, along with specific ratios of wetting agents and water-dispersible resins, to ensure aggregation and improved wettability, reducing bleeding and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inks with high pigment concentration or solid content are used to increase image density, then image density is improved, but ink discharge reliability deteriorates
Solution Approach 1:
The patent adjusts the surface tension of high-concentration inks by adding specific surfactants (anionic, cationic, or nonionic types) to ensure the surface tension is within the range of 20-40 mN/m. This parameter change allows the ink to maintain proper flow and discharge characteristics from the recording head while preserving the high pigment concentration needed for dense images.
2Speed
If ink permeability is enhanced to increase ink dry speed, then ink dry speed is improved, but bleeding occurs in the printed image
Solution Approach 1:
The patent employs a two-component ink system where one ink contains a water-dispersible colorant without surfactant-based dispersant and the other contains a surfactant-based dispersant. This creates local differences in surface tension and permeability characteristics, allowing controlled ink absorption that prevents bleeding while maintaining acceptable drying speed.
Solution Approach 2:
The patent uses composite ink formulations combining different types of surfactants (anionic, cationic, nonionic) with water-dispersible colorants and resins. This composite approach creates an ink system with balanced surface tension and controlled permeability, achieving both fast drying and bleeding prevention.
3Manufacturing precision
If multi-pass printing is employed to suppress ink permeation and increase image density, then image density is improved, but printing speed deteriorates
Solution Approach 1:
The patent modifies the ink's surface tension and composition to achieve optimal permeability characteristics in a single pass. By adjusting surfactant concentration and type, the ink is formulated to provide sufficient density without requiring multiple passes, thereby maintaining high printing speed.
4Object-generated harmful factors
If pectin is added as a thickener to prevent bleeding, then bleeding is prevented, but discharge stability after downtime deteriorates
Solution Approach 1:
The patent removes pectin and similar thickening agents from the ink formulation. Instead, it relies on surfactant-based surface tension control and optimized pigment dispersion to prevent bleeding, thereby maintaining discharge stability and avoiding the clogging problems associated with thickening agents.
5Object-generated harmful factors
If ink surface tension is reduced to improve wetting and prevent bleeding, then bleeding is reduced, but ink discharge reliability deteriorates
Solution Approach 1:
The patent optimizes surfactant concentration and type to achieve a balanced surface tension range (20-40 mN/m). This parameter optimization ensures sufficient wetting to prevent bleeding while maintaining proper flow characteristics for reliable discharge from the recording head, avoiding both bleeding and discharge failures.
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 enables high-speed printing of sharp, high-resolution color images with reduced bleeding and improved storage stability, suitable for regular paper with poor ink absorbability, by controlling the surface tension and adhesion properties of the mixed ink.
Implementation Method 1
one ink contains a water-dispersible colorant without a surfactant-based dispersant and the other contains a surfactant-based dispersant, along with specific ratios of wetting agents and water-dispersible resins, to ensure aggregation and improved wettability
Implementation Method 2
the other contains a surfactant-based dispersant
Implementation Method 3
improved wettability, reducing bleeding and enhancing image quality
Data Source
AI summary
An ink set includes at least two aqueous inks A and B with different colors, the inks A and B used in an inkjet recording method in which the inks A and B are superimposed for formation of a color image, wherein the ink A contains water-dispersible colorant A1 free of a surfactant-based dispersant, and anionic compound A2, and wherein the ink B contains water-dispersible colorant B1 containing a surfactant-based dispersant.