Oil-Based Inkjet Printing Method for Sharp Text and Low Show-Through
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Solution Overview
Problem
The inkjet recording method faces challenges in achieving high print density and sharpness of fine text while minimizing show-through in printed items, particularly with oil-based inks, due to issues with ink penetration and spreading characteristics.
Innovation Solution
A method involving the discharge of two oil-based inkjet inks with different surface tensions and discharge volumes, where a first ink with a surface tension less than 27.0 mN/m is discharged at a volume of at least 20 pl to form dots, followed by a second ink with a surface tension of 27.0 mN/m or greater, discharged at a volume less than 20 pl, to overlap and enhance dot density and prevent show-through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oil-based ink is discharged to improve print density, then colorant penetration increases, but show-through worsens
Solution Approach 1:
The inkjet printing process is segmented into two distinct stages: first discharging a base layer ink at larger volume (≥20 pl) to establish coverage and density, then discharging a highlight ink at smaller volume (<20 pl) to enhance sharpness and reduce show-through. This segmentation allows each ink layer to serve a specific function, resolving the contradiction between achieving high print density and minimizing show-through.
Solution Approach 2:
Different regions of the printed image receive different ink treatments: the base layer provides uniform coverage across the entire image area, while the highlight ink is selectively applied to specific regions requiring enhanced sharpness. This local quality approach ensures that show-through suppression is applied where most needed while maintaining overall print density.
2Quantity of substance
If ink discharge volume is increased to improve print density, then dot coverage improves, but dot accuracy deteriorates
Solution Approach 1:
The ink discharge process is divided into two sequential operations with different volume parameters: the first discharge uses ≥20 pl droplets optimized for coverage, while the second discharge uses <20 pl droplets optimized for precision. This segmentation allows the system to achieve both high dot coverage and high dot accuracy that would be impossible with a single discharge volume.
Solution Approach 2:
The base layer ink is discharged first to establish the fundamental dot coverage and image structure. Subsequently, the highlight ink is discharged to refine and sharpen specific features. This preliminary action approach ensures that the larger volume ink provides the coverage foundation, while the smaller volume ink adds precision without compromising the established coverage.
3Stability of the object's composition
If ink surface tension is decreased to improve spreading, then ink dispersion improves, but penetration control worsens
Solution Approach 1:
The ink system is segmented into two formulations with different surface tension characteristics: the base layer ink has lower surface tension (<27.0 mN/m) optimized for dispersion and coverage, while the highlight ink has higher surface tension (≥27.0 mN/m) optimized for penetration control and sharpness. This segmentation allows each ink type to excel at its specific function without compromise.
Solution Approach 2:
Different surface tension properties are applied to different ink layers based on their functional requirements: the base layer uses low surface tension ink where superior dispersion is the priority, while the highlight layer uses high surface tension ink where penetration control is the priority. This local quality approach matches material properties to functional requirements.
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 approach effectively suppresses show-through and improves the sharpness of fine text by ensuring rapid fixation and uniform dispersion of the first ink, while the second ink's higher surface tension and lower volume help in maintaining dot accuracy and preventing excessive penetration, resulting in improved print quality.
Implementation Method 1
a first oil-based inkjet ink containing a first colorant and a non-aqueous solvent and having an ink surface tension of less than 27.0 mN/m, and a second oil-based inkjet ink containing a second colorant and a non-aqueous solvent and having an ink surface tension of 27.0 mN/m or greater
Data Source
AI summary
A method for producing a printed item including discharging two or more inks by an inkjet method toward a recording medium to form an image is disclosed, wherein the two or more inks include a first oil-based inkjet ink containing a first colorant and a non-aqueous solvent and having an ink surface tension of less than 27.0 mN/m, and a second oil-based inkjet ink containing a second colorant and a non-aqueous solvent and having an ink surface tension of 27.0 mN/m or greater, and the method includes discharging the first oil-based inkjet ink toward the recording medium at a discharge volume of at least 20 pl per one liquid droplet to form dots with the first oil-based inkjet ink, and subsequently discharging the second oil-based inkjet ink toward the recording medium at a discharge volume of less than 20 pl per one liquid droplet so as to overlap with the dots formed with the first oil-based inkjet ink.