Ink-Jet Ink Composition Stabilizing Pigment Dispersion
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Solution Overview
Problem
Ink-jet applications require low viscosity inks to dispense fine droplets, but low viscosity inks easily sediment and aggregate, making uniform dispensing difficult, especially when stored in ink cartridges with absorbers.
Innovation Solution
An ink composition comprising a solvent, a pigment with a surface charge, an ionic polymer bearing an opposite charge, and a polyvalent ion, which suppresses sedimentation and aggregation by forming a weak flocculation network, allowing for stable dispensing even with pigments prone to sedimentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ink viscosity is reduced to enable fine droplet dispensing, then dispensing performance is improved, but pigment sedimentation and aggregation worsen
Solution Approach 1:
The patent introduces a pigment dispersing agent as an intermediary substance between the pigment and the continuous phase. This dispersing agent has a unique molecular structure with a nonionic polyalkylene glycol chain and an anionic group, which acts as a mediator to prevent pigment aggregation while maintaining low viscosity for good dispensing performance.
Solution Approach 2:
The patent optimizes specific parameters of the pigment dispersing agent, including the average number of moles of alkylene oxide (15-100), acid value (100-400 mgKOH/g), and content relative to pigment (0.3-18 parts by mass per 100 parts pigment). These parameter changes enable the system to achieve both low viscosity and pigment stability simultaneously.
2Quantity of substance
If pigment powder is added to low viscosity ink, then color strength and concealing ability are improved, but sedimentation and aggregation worsen
Solution Approach 1:
The pigment dispersing agent serves as a mediator that enables higher pigment concentrations to be maintained in suspension. The dispersing agent adsorbs onto pigment surfaces, providing steric and electrostatic stabilization that prevents aggregation even at high pigment loadings, thus maintaining both color strength and suspension stability.
Solution Approach 2:
The patent creates a composite system consisting of pigment particles, nonionic polyalkylene glycol chain, and anionic group components. This composite structure forms a stabilized pigment dispersion where the dispersing agent is intimately associated with the pigment, enabling high pigment concentration without sedimentation.
3Quantity of substance
If ink is stored in absorber-based ink cartridges, then ink storage capacity is improved, but pigment redispersion capability worsens
Solution Approach 1:
The pigment dispersing agent acts as a mediator that prevents pigment particles from firmly adhering to the absorber matrix. The dispersing agent maintains pigment particles in a loose, redispersible state even when stored in absorber-based cartridges, enabling easy redispersion during subsequent dispensing operations.
Solution Approach 2:
The pigment dispersing agent provides self-service functionality by maintaining pigment particles in a state that automatically redisperses upon contact with the continuous phase during dispensing. The dispersing agent's molecular structure enables it to continuously stabilize pigment particles without requiring external intervention, ensuring ease of operation throughout the ink cartridge's service life.
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 composition effectively prevents sedimentation and aggregation, enabling stable and uniform dispensing in ink-jet applications, including those with absorbers, and maintains high concealing ability with suitable particle sizes.
Implementation Method 1
an ionic polymer bearing a second charge that is opposite to the first charge
Implementation Method 2
which suppresses sedimentation and aggregation by forming a weak flocculation network
Implementation Method 3
a polyvalent ion bearing the first charge
Implementation Method 4
A surface-tension of the ink composition is 53 mN/m or smaller
Data Source
AI summary
An ink-jet ink composition includes: a solvent; a pigment comprising a first powder, the surface of which, in the solvent, bears a first charge; an ionic polymer having a second charge, which is counter to the first charge; and polyvalent ions having the first charge. The ink composition has a surface tension of 53 mN/m or less.