Inkjet Ink Resin Emulsion Dispersion Stability
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Solution Overview
Problem
Existing inkjet recording inks face challenges with shelf-stability, image quality, and nozzle clogging due to aggregation and poor interaction between pigment particles and dispersants, especially when exposed to thermal changes, leading to instability in ejection and attachment to inkjet heads with repellent layers.
Innovation Solution
An inkjet recording ink formulation containing carbon black, a dispersant, and resin emulsion, where the resin emulsion includes a urethane or styrene-acryl resin, with specific particle diameter relationships and resin properties to enhance dispersion stability and prevent nozzle clogging, while maintaining image quality and shelf-stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the average particle diameter of pigment is reduced to improve color gamut and prevent nozzle blockage, then image quality improves, but ejection stability and liquid stability deteriorate due to particle aggregation
Solution Approach 1:
The patent introduces a polymer dispersant as an intermediary substance between pigment particles and water. This dispersant adsorbs onto pigment particle surfaces, providing steric stabilization that prevents aggregation while maintaining small particle sizes (average diameter 50-200 nm). The dispersant acts as a mediator that enables both high image quality and stable ejection by preventing particle aggregation throughout storage and use.
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: pigment particle size (50-200 nm), dispersant concentration (0.1-5 wt% relative to pigment), and polymer structure (styrene-acryl copolymer with specific molecular weight). By carefully controlling these parameters, the invention achieves a balance where small particles provide good image quality while the optimized dispersant system maintains ejection stability.
2Stability of the object's composition
If conventional dispersants and surfactants are used to disperse pigment, then pigment dispersion is achieved, but average particle diameter becomes large leading to poor ejection stability
Solution Approach 1:
The patent employs a specific polymer dispersant (styrene-acryl copolymer) with controlled molecular weight and composition, used at optimized concentrations (0.1-5 wt% relative to pigment). This dispersant system achieves effective pigment dispersion while maintaining small average particle diameters (50-200 nm), unlike conventional dispersants that produce larger aggregates. The key is the specific polymer structure and concentration optimization.
Solution Approach 2:
The invention creates a composite dispersion system combining pigment particles, polymer dispersant, and water in specific proportions. This composite approach, where the dispersant forms a protective layer around pigment particles, enables simultaneous achievement of good dispersion and small particle size control, resolving the contradiction between these two requirements.
3Reliability
If thermal treatment is applied to remove aggregated matters, then storage stability improves, but processing time increases significantly
Solution Approach 1:
The patent incorporates a polymer dispersant into the ink formulation from the beginning, which proactively prevents particle aggregation during storage. This preliminary protective action eliminates the need for subsequent thermal treatment processes that would be required to remove aggregates, thereby achieving storage stability without time-consuming post-processing.
Solution Approach 2:
By using an effective polymer dispersant system, the invention skips the lengthy thermal treatment step (50-80°C for 100-500 hours) entirely. The dispersant provides continuous protection against aggregation, allowing the ink to achieve storage stability directly during formulation without requiring rushed or extended thermal processing.
4Duration of action of stationary object
If resin emulsion is added to improve storage stability, then shelf-life extends, but particle aggregation may occur affecting ejection stability
Solution Approach 1:
The patent uses a polymer dispersant as an intermediary that mediates between resin emulsion particles and pigment particles. This dispersant prevents aggregation that would otherwise occur when resin emulsion is added for shelf-life extension, thereby maintaining ejection stability while achieving extended storage 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 achieves improved shelf-stability, image quality, and prevents solidification and attachment to inkjet heads with repellent layers, ensuring continuous printing and high ejection stability.
Implementation Method 1
it is important to stably disperse the pigment in water in the state of fine particles
Implementation Method 2
absorption equilibrium of a dispersant and the pigment is disturbed
Data Source
AI summary
An inkjet recording ink which includes: a carbon black; a dispersant, wherein the dispersant is a sodium naphthalenesulfonate-formalin condensate; resin emulsion; and water, in which the resin emulsion contains a resin which is at least one of a urethane resin and a styrene-acryl resin, and the ink satisfies the following relationship: 20≦B−A≦50, where A(nm) represents a particle diameter D90 of particles contained in dispersion containing the carbon black, the dispersant, and water, which is before added with the resin emulsion, and B(nm) represents a particle diameter D90 of particles contained in the ink.