Inkjet Multi-Pass Clear Coat Timing for Pinhole-Free Printing
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Solution Overview
Problem
Existing ink jet recording methods suffer from pinholes and inferior image filling properties due to insufficient ink adhesion and abrasion resistance, primarily caused by the reaction between treatment liquids and ink droplets, leading to decreased wet-spreadability and coarse particle formation.
Innovation Solution
A multi-pass recording method where a color ink composition is applied in multiple passes, followed by a clear ink composition in a predetermined amount during the final pass, suppressing the reaction between the color ink and treatment liquid, enhancing wet-spreadability and protecting the ink coating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a treatment liquid is used to rapidly fix ink droplets on the recording medium, then the recording speed is improved, but pinholes and inferior image filling properties are generated due to insufficient ink adhesion
Solution Approach 1:
The recording process is divided into multiple passes where color ink is applied in at least two separate scans, with a clear ink scan positioned between them. This segmentation allows the treatment liquid to act on the color ink in controlled intervals rather than continuously, preventing excessive reaction that causes pinholes while ensuring complete coverage and filling properties.
Solution Approach 2:
A clear ink composition containing resin is introduced as an intermediary layer between the color ink and the treatment liquid. This intermediary scan suppresses the harmful reaction between the treatment liquid and color ink by acting as a barrier, while still allowing the treatment liquid to function effectively on the color ink in previous scans, thus maintaining both recording speed and image quality.
2Speed
If the treatment liquid reacts with the ink droplet, then the ink is rapidly fixed on the recording medium, but the wet-spreadability decreases and coarse particles are formed
Solution Approach 1:
The clear ink scan is positioned as a preliminary action before the final color ink scan. By applying the clear ink containing resin in advance, the system prepares a protective layer that will suppress harmful reactions during subsequent treatment liquid application, ensuring stable wet-spreadability while maintaining rapid fixing capability in earlier scans.
Solution Approach 2:
The clear ink composition serves as an intermediary layer that modulates the interaction between the treatment liquid and color ink. It allows the treatment liquid to rapidly fix the color ink in previous scans while preventing excessive reaction in later scans, thus maintaining both fixing speed and wet-spreadability stability.
3Manufacturing precision
If multiple scans are performed to improve ink adhesion, then the image filling property is improved, but the recording time increases
Solution Approach 1:
Multiple functional scans are merged into a single pass: the clear ink scan simultaneously serves as a protective barrier for the color ink, a filler for pinholes, and a suppressor of harmful reactions. This merging of functions into one scan reduces the total number of passes required compared to performing each function separately, thus improving image filling property while minimizing time loss.
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 improves image quality and filling properties while increasing abrasion resistance by ensuring the clear ink composition adheres to the recording medium in a sufficient amount, particularly on low- or non-absorbing surfaces.
Implementation Method 1
a step of adhering a treatment liquid containing an aggregating agent to the recording medium
Implementation Method 2
a step of ejecting a color ink composition containing a colorant from the ink jet head so as to be adhered to the recording medium
Implementation Method 3
a step of ejecting a clear ink composition containing a resin from the ink jet head so as to be adhered to the recording medium
Implementation Method 4
suppressing the reaction between the color ink and treatment liquid, enhancing wet-spreadability
Implementation Method 5
protecting the ink coating film, increasing abrasion resistance
Data Source
AI summary
A recording method according to an embodiment of the present disclosure is a recording method to perform recording on a recording medium in a manner such that while a relative position between an ink jet head and the recording medium is transferred, a scan to eject an ink from the ink jet head so as to be adhered to the recording medium is performed a plurality of times for the recording. The method described above includes a step of adhering a treatment liquid containing an aggregating agent to the recording medium; a step of ejecting a color ink composition containing a colorant from the ink jet head so as to be adhered to the recording medium; and a step of ejecting a clear ink composition containing a resin from the ink jet head so as to be adhered to the recording medium. In the recording method described above, the color ink composition is adhered to the same scan region by performing the scan at least two times, the clear ink composition is adhered by the same scan as a final scan of the at least two scans to a scan region of the recording medium to which the color ink composition is adhered, and an adhesion amount of the clear ink composition adhered by the final scan in the region to which the color ink composition and the clear ink composition are adhered is 80 percent by mass or more of a total adhesion amount of the clear ink composition in the region.