Ink Formulation for High-Speed Inkjet Printing
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Solution Overview
Problem
Inkjet recording technologies face challenges in achieving high optical density and fixability while preventing feathering and strike-through, especially at high conveying speeds, as existing inks either suffer from low fixability or inadequate optical density due to limitations in permeation time and viscosity.
Innovation Solution
An ink formulation with a viscosity of 5 mPa·s or more, static surface tension between 27.1 mN/m and 35.0 mN/m, and dynamic surface tension between 30.5 mN/m and 37.0 mN/m, incorporating a pigment, water-soluble organic solvent, and surfactant, which controls permeation time and surface tension to balance optical density and fixability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If superpermeable ink is used to improve fixability, then permeation speed increases, but optical density decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the ink within 3-15 mPa·s and the surface tension within 25-35 mN/m. These parameter adjustments optimize the balance between permeation speed (for fixability) and pigment retention (for optical density), resolving the contradiction between fast drying and high color density.
Solution Approach 2:
The patent uses composite materials by formulating ink with specific combinations of solvents (glycol ethers, diols, carboxylic acid esters) and surfactants. This composite approach creates an ink system that achieves both rapid permeation for fixability and sufficient pigment concentration for optical density, combining the benefits of different material properties.
2Illumination intensity
If overlay ink is used to improve optical density, then permeation time increases, but fixability worsens
Solution Approach 1:
The patent reverses the overlay ink approach by using parameter changes to reduce viscosity to 3-15 mPa·s and adjust surface tension to 25-35 mN/m. These changes accelerate permeation time to seconds or less while maintaining high optical density through optimized pigment-solvent-surfactant interactions, thus improving both optical density and fixability simultaneously.
3Speed
If ink viscosity is reduced to improve ejection stability, then permeation speed increases, but feathering increases
Solution Approach 1:
The patent applies parameter changes by setting viscosity within 3-15 mPa·s and surface tension within 25-35 mN/m, creating an optimal balance where the ink permeates quickly enough for high-speed printing but maintains sufficient cohesion to prevent feathering. This resolves the contradiction between permeation speed and feathering suppression.
Solution Approach 2:
The patent uses composite materials by combining specific solvent types (glycol ethers, diols, carboxylic acid esters) with surfactants in controlled amounts. This composite formulation ensures rapid permeation while the surfactant system maintains ink cohesion, preventing feathering even at low viscosities required for high-speed ejection.
4Productivity
If conveying speed is increased to improve productivity, then printing speed increases, but image quality deteriorates due to insufficient permeation time
Solution Approach 1:
The patent applies parameter changes by reducing ink viscosity to 3-15 mPa·s and adjusting surface tension to 25-35 mN/m, which dramatically increases permeation speed. This allows the ink to fully permeate and fix to the paper within the reduced contact time at high conveying speeds, maintaining image quality (optical density and color fastness) while achieving high productivity.
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 high optical density and fixability with reduced feathering and strike-through, suitable for high-speed recording, maintaining ejection stability and preventing contamination of conveying rollers.
Implementation Method 1
a static surface tension of 27.1 mN/m or more and 35.0 mN/m or less, which is measured at 25°C by a Wilhelmy method, and a dynamic surface tension of 30.5 mN/m or more and 37.0 mN/m or less, which is measured at 25°C by a maximum bubble pressure method
Implementation Method 2
an ink droplet applied to the surface of the recording medium (plain paper) permeates a gap between cellulose fibers constituting the plain paper
Implementation Method 3
the ink has a viscosity of 5 mPa·s or more at 25°C
Data Source
Figure 1~2
AI summary
Provided is an ink containing a pigment, a water-soluble organic solvent, and a surfactant represented by the following general formula (1), and having a viscosity at 25°C of 5 mPa·s or more. The ink has a static surface tension of 27.1 mN/m or more and 35.0 mN/m or less, which is measured at 25°C by a Wilhelmy method. The ink also has a dynamic surface tension at a bubble life time of 150 msec of 30.5 mN/m or more and 37.0 mN/m or less, which is measured at 25°C by a maximum bubble pressure method.