Inkjet Ink Viscosity Control for Storage and Ejection Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional inkjet inks face challenges in achieving high-quality images on plain paper with high-speed printing while maintaining storage and ejection stability, and they often require high maintenance for inkjet recording apparatuses, with issues such as feathering, white spots, and poor rubfastness.
Innovation Solution
An inkjet ink formulation including a water dispersion of pigment-containing water-insoluble vinyl polymer particles, a water-soluble organic solvent, and specific monomers, adjusted to have a viscosity of 3,000 mPa·s or less when left to stand and a pH-adjusted viscosity of 500 mPa·s or more, which inhibits pigment absorption into paper and enhances image quality and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a polymer compound is used to disperse pigment in water, then storage stability is improved, but ejection stability deteriorates due to aggregation from water evaporation
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer compound, specifically using a vinyl polymer with hydrophobic functional groups and controlling the polymer's molecular weight and structure. This allows the ink to maintain stability during storage while preventing excessive aggregation during ejection, resolving the contradiction between storage stability and ejection stability.
Solution Approach 2:
The patent creates a composite system by combining pigment particles with a specifically designed vinyl polymer compound that has both hydrophilic and hydrophobic characteristics. This composite structure allows the pigment to be stably dispersed in water during storage while controlling aggregation behavior during the evaporation process, thereby maintaining both storage and ejection stability.
2Manufacturing precision
If ink viscosity is increased to prevent pigment spreading, then image quality is improved, but ejection stability deteriorates
Solution Approach 1:
The patent carefully controls the viscosity parameter within a specific range (50-200 mPa·s at 25°C) by adjusting the polymer concentration and molecular weight. This optimized viscosity range provides sufficient pigment holding power to prevent spreading while maintaining low enough viscosity for stable ejection, resolving the contradiction between image quality and ejection stability.
3Manufacturing precision
If a water-insoluble vinyl polymer is used to fix pigment, then image density is improved, but aggregation property increases causing ejection instability
Solution Approach 1:
The patent introduces hydrophobic functional groups at specific locations on the polymer chain to create local hydrophobic regions. These localized hydrophobic groups provide strong pigment binding capability for high image density while the overall polymer structure remains sufficiently hydrophilic to prevent excessive aggregation during ejection, resolving the contradiction between image density and ejection stability.
4Productivity
If ink is concentrated for high-speed printing, then productivity is improved, but viscosity increases causing ejection problems
Solution Approach 1:
The patent optimizes the polymer compound's molecular weight and structure to maintain low viscosity even at higher pigment concentrations. The specific vinyl polymer structure with controlled molecular weight (10,000-1,000,000) allows the ink to achieve high pigment loading for high-speed printing while keeping viscosity within the acceptable range for stable ejection.
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 inkjet ink achieves excellent image quality with improved image density, color saturation, reduced feathering and white spots, and enhanced storage and ejection stability, while minimizing maintenance load on the recording apparatus.
Implementation Method 1
a water dispersion of pigment-containing water-insoluble vinyl polymer particles
Implementation Method 2
a method for suppressing thickening of the ink having a high pigment concentration upon water evaporation
Implementation Method 3
the inkjet ink, pH of which is adjusted to 7 with an acid has a viscosity of 500 mPa·s or more
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention provides an inkjet ink which is excellent in image quality and high-speed printing on plain paper, in storage stability and in ejection stability and gives less load on a maintenance device for an inkjet recording apparatus; and an ink cartridge, an inkjet recording apparatus, and an inkjet recording method, using the inkjet ink. An inkjet ink containing a water dispersion of pigment-containing water-insoluble vinyl polymer particles; a water-soluble organic solvent; and water, wherein an ink residue from the inkjet ink has a viscosity of 3,000 mPa s or less, the ink residue is obtained by leaving the inkjet ink to stand at a temperature of 25? and a humidity of 15% until substantially no mass change occurs, and wherein the inkjet ink, pH of which is adjusted to 7 with an acid, has a viscosity of 500 mPa s or more.