Ink Set Viscosity Control for Discharge Stability
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Solution Overview
Problem
Inkjet recording apparatuses using pigment inks face challenges with discharge stability due to clogging caused by thickened ink and foreign matter, particularly with high pigment concentration inks like black carbon ink, which leads to non-recoverable discharge failures.
Innovation Solution
An ink set comprising a black ink with resin-coated and surfactant-treated carbon-black particles, and a color ink with resin-coated and surfactant-treated color-pigment particles, optimized to maintain stable viscosity and prevent clogging, where the black ink includes 5.0% to 12.0% carbon black and the color ink includes 3.0% to 10.0% pigment, with specific mass ratios to ensure effective suction and discharge recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pigment concentration in black ink is increased to achieve high image density, then the image density is improved, but the ink viscosity increases and causes clogging leading to discharge failure
Solution Approach 1:
The patent applies parameter changes by carefully controlling the pigment concentration within a specific range (5.0% to 12.0% by mass) and adjusting the pH value (6.0 to 9.0) to optimize the balance between image density and discharge stability. This resolves the contradiction by finding the optimal parameter values that satisfy both requirements simultaneously.
Solution Approach 2:
The patent uses composite materials by combining carbon black particles with specific resin coatings and surfactants. This composite structure modifies the ink's rheological properties, allowing high pigment concentration to be achieved while maintaining low viscosity and preventing clogging, thus resolving the contradiction between image density and discharge stability.
2Device complexity
If a common cap is used to suck viscous inks from multiple nozzle arrays, then the structure is simplified, but only low viscosity color inks are sucked while high viscosity black ink cannot be sucked
Solution Approach 1:
The patent applies parameter changes by controlling the viscosity of black ink to be lower than that of color inks through pH adjustment and additive selection. This parameter optimization allows a common cap to effectively suck both black and color inks, resolving the contradiction between device simplicity and discharge recovery reliability.
3Reliability
If the black ink viscosity is reduced to enable effective suction, then the discharge recovery is improved, but the image density may be compromised
Solution Approach 1:
The patent simultaneously optimizes multiple parameters including pH value (6.0 to 9.0), pigment concentration (5.0% to 12.0%), and viscosity relationships between black and color inks. This multi-parameter optimization ensures that the black ink has sufficiently low viscosity for effective suction while maintaining high pigment concentration for adequate image density, resolving the contradiction between discharge recovery and image density.
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 provides high image density and superior discharge stability and recovery, reducing the likelihood of clogging and non-recoverable discharge failures, while maintaining sufficient pigment concentration for image quality.
Implementation Method 1
surfactant-treated carbon-black particles including carbon black and a surfactant existing on a surface of the carbon black
Implementation Method 2
resin-coated carbon-black particles including carbon black and a resin existing on a surface of the carbon black
Implementation Method 3
a sucking-and-covering unit which covers the recording head and communicates with a suction-generating unit
Data Source
AI summary
An ink set, used in an inkjet recording apparatus equipped with a recording head including: a plurality of nozzle arrays, each including a plurality of nozzles; and a sucking-and-covering unit for covering the recording head, wherein the black ink is supplied to one of the plurality of the nozzle arrays of the recording head, and the color ink is supplied to the other plurality of the nozzle arrays of the recording head, wherein the black ink includes resin-coated carbon-black particles, surfactant-treated carbon-black particles and water, wherein the color ink includes resin-coated color-pigment particles, surfactant-treated color-pigment particles and water, and wherein the ink set satisfies Expression (1), Expression (2) and Expression (3) below:5.0% by mass≦P(Bk)≦12.0% by mass Expression (1)3.0% by mass≦P(CL)≦10.0% by mass Expression (2)[R(CL)/S(CL)]<[R(Bk)/S(Bk)] Expression (3).