Ink Jet Recording Head Ejection Stability
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Solution Overview
Problem
Ink jet recording methods using line heads face challenges in maintaining ejection stability over long periods while increasing optical density, as the aggregation of pigments can lead to decreased ejection amounts and non-ejection issues due to ink thickening and stagnation.
Innovation Solution
The use of aqueous ink containing self-dispersible pigments with anionic groups bonded to their surfaces and a nonionic surfactant, where the surface charge amount of the pigment is 0.40 mmol/g or less, to improve ejection stability and optical density by preventing excessive aggregation and maintaining a stable dispersion state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aggregation property of pigment is increased to increase optical density, then the optical density of the image is improved, but the ejection stability of ink deteriorates due to ink thickening and stagnation
Solution Approach 1:
The patent changes the chemical parameters of the ink composition by specifying a surface charge amount of 0.40 mmol/g or less for self-dispersible pigments and controlling the HLB value of nonionic surfactants within 10.0-20.0. These parameter changes optimize the balance between pigment aggregation for optical density and ink flow stability for ejection performance
Solution Approach 2:
The patent uses composite material formulation by combining self-dispersible pigments with specific nonionic surfactants having controlled HLB values. This composite approach creates a synergistic effect where the surfactant modifies the pigment dispersion properties to achieve both high optical density and stable ejection over long periods
2Productivity
If a line head is used to record images in single pass to increase recording speed, then the recording speed is improved, but it becomes difficult to perform recovery operations from nozzles with low ejection frequency
Solution Approach 1:
The patent applies preliminary action by continuously flowing ink through the first flow path to the second flow path even during periods when no ejection occurs. This preliminary maintenance of ink flow prevents ink thickening and stagnation in advance, ensuring that nozzles remain ready for ejection without requiring complex recovery operations
Solution Approach 2:
The patent implements continuity of useful action by maintaining constant ink circulation through the flow paths separate from the ejection process. This continuous ink movement ensures that all nozzles, including those with low ejection frequency, receive fresh ink continuously, preventing stagnation and maintaining ejection capability throughout the recording period
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
This configuration enhances long-term ejection stability and achieves high optical density by preventing ink thickening and adhesion, ensuring consistent ink flow and improved image quality.
Implementation Method 1
a self-dispersible pigment in which an anionic group is bonded to a particle surface of the pigment directly or through another atomic group, and a nonionic surfactant, the self-dispersible pigment having a surface charge amount of 0.40 mmol/g or less
Implementation Method 2
a nonionic surfactant, the self-dispersible pigment having a surface charge amount of 0.40 mmol/g or less
Data Source
AI summary
An object of the present invention is to provide an ink jet recording method capable of exhibiting excellent ejection stability of ink even after recording an image over a long period of time, while recording an image having a high optical density. The ink jet recording method is a method of recording an image by ejecting ink from a recording head including an ejection orifice ejecting the ink, an ejection element generating energy for ejecting the ink, and first and second flow paths which communicate between the ejection orifice and the ejection element and in which the ink flows. The ink jet recording method includes an ejection step of ejecting the ink from the ejection orifice; and a flow step of flowing the ink in the first flow path to the second flow path separately from the ejection step, wherein the ink is aqueous ink containing a self-dispersible pigment in which an anionic group is bonded to a particle surface of the pigment directly or through another atomic group, and a nonionic surfactant, the self-dispersible pigment having a surface charge amount of 0.40 mmol/g or less.