Water Base Ink Set for Regular Paper Bleeding
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Solution Overview
Problem
Ink-jet recording on regular paper faces challenges with bleeding and discharge stability due to the interaction of black and color inks, particularly caused by the use of dispersing agents and permeating agents which can lead to non-uniform blurring, solidification, and nozzle clogs.
Innovation Solution
A water-based ink set combining a negatively-chargeable and self-dispersible black pigment with a color ink containing a dye having a specific fluorescein structure and an alkylamine ethylene oxide adduct, ensuring uniform negative charging and preventing pigment aggregation, while using the same water-soluble organic solvent in both inks to maintain stability and prevent solvent shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dispersing agent is used to disperse black pigment, then the black ink can be prepared, but the ink causes non-uniform blurring and solidification when water evaporates
Solution Approach 1:
The invention extracts and removes the dispersing agent from the ink formulation, using only self-dispersible pigments that do not require external dispersants. This eliminates the harmful effects of dispersing agents while maintaining dispersion stability through the pigment's inherent surface properties.
Solution Approach 2:
The black pigment is designed to be self-dispersible through surface oxidation treatment, allowing it to disperse in water without requiring external dispersing agents. The pigment particles themselves provide the necessary dispersion stability through their charged surfaces.
2Ease of manufacture
If a self-dispersible pigment is used, then dispersing agents are eliminated, but pigment aggregation occurs when ink contacts salt-based dye color ink
Solution Approach 1:
The invention introduces a surfactant as an intermediary substance that mediates between the self-dispersible black pigment and the salt-based dye color ink. The surfactant prevents direct harmful interactions that would cause aggregation, allowing both ink types to coexist without nozzle clogging.
3Speed
If permeating agents are added to improve ink permeability, then the ink penetrates paper better, but aggregation occurs when black and color inks contact
Solution Approach 1:
The surfactant acts as an intermediary that enables improved permeability while preventing aggregation. It modifies the surface tension and wetting properties to enhance paper penetration, simultaneously preventing harmful interactions between black and color inks during the permeation process.
4Ease of operation
If water base dye ink is used for regular paper, then handling performance is excellent, but bleeding occurs between different colors
Solution Approach 1:
The invention segments the ink system into distinct charged components: negatively charged self-dispersible black pigment and positively charged salt-based dye color ink. This charge separation prevents the bleeding and mixing that occurs with conventional water base dye inks, while maintaining excellent handling performance on regular paper.
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 effectively suppresses bleeding and ensures stable discharge, preventing pigment aggregation and nozzle clogs, thus achieving high-quality printing on regular paper with improved reliability and cost-effectiveness.
Implementation Method 1
the self-dispersible pigment, in which the dispersion stability relies only on the electrostatic repulsive force
Implementation Method 2
blend a permeating agent such as a water-soluble polyvalent alcohol alkyl ether and a surfactant into the ink in order to decrease the surface tension of the ink
Implementation Method 3
when the water content in the ink is decreased after the evaporation of water
Data Source
AI summary
A water base ink set for ink-jet recording includes a black ink containing water, a black pigment and a water-soluble organic solvent and a color ink containing water, a dye, and a water-soluble organic solvent. The black pigment is a negatively-chargeable and self-dispersible pigment. The dye has a fluorescein structure. The color ink further contains an alkylamine ethylene oxide adduct. The water-soluble organic solvent contained in the black ink is same as that contained in the color ink. With the ink set, not only the bleeding hardly occurs but also satisfactory discharge stability is obtained even when an ink-jet recording is performed on a regular paper.