Inkjet White-Underlayer Drying for Low-Wettability Media
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Solution Overview
Problem
Aqueous pigment ink used in inkjet recording apparatuses tends to repel and blot on recording media with low wettability, such as plastic sheets, due to inadequate ink adhesion and drying issues.
Innovation Solution
The use of white ink containing resin particles with a minimum film formation temperature of 40° C. to 80° C. and non-white ink with resin particles of 80° C. or less, combined with a drying process where the first drying temperature is lower than the resin particles' minimum film formation temperature and the second drying temperature is higher than both, ensures proper ink adhesion and drying on low-wettability media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If aqueous pigment ink is ejected onto a recording medium with low wettability such as a plastic sheet, then the recording medium can be used for various applications, but the ink tends to repel and blot, causing poor adhesion and image quality
Solution Approach 1:
A white ink background layer is applied to the recording medium before the main image is formed. This preliminary application of white ink modifies the surface properties of the low-wettability medium, creating a more favorable surface for subsequent ink application. The white ink layer acts as a preparatory treatment that enhances the adhesion and prevents blotting of the following non-white ink, thereby solving the problem of poor ink adhesion on low-wettability surfaces while maintaining the versatility of the recording medium.
2Reliability
If a background layer of white ink is formed before the image, then ink repelling and blotting is prevented, but the drying process becomes more complex requiring multiple drying stages with specific temperature controls
Solution Approach 1:
The drying process is divided into two distinct stages: a first drying stage for the white ink background layer and a second drying stage for the non-white ink image. Each stage has specific temperature parameters optimized for the respective ink type. The first drying stage uses lower temperature to prevent premature film formation of the white ink, while the second drying stage uses higher temperature to properly dry the non-white ink. This segmentation allows each drying stage to be optimized independently, managing the complexity through structured process division rather than requiring a single complex drying system.
Solution Approach 2:
The drying temperature parameter is changed between the two drying stages. The first drying stage operates at a lower temperature (below the minimum film formation temperature of the white ink resin particles) to prevent premature film formation and ensure proper drying. The second drying stage operates at a higher temperature (equal to or above the minimum film formation temperature) to properly dry the non-white ink. This parameter change approach allows the system to handle different ink types with different drying requirements, managing complexity through parameter optimization rather than structural complexity.
3Productivity
If resin particles with low minimum film formation temperature are used in white ink, then the white ink dries faster, but the resin may form a film too early preventing proper drying and adhesion
Solution Approach 1:
The minimum film formation temperature of the resin particles in the white ink is specifically controlled to be between 40°C and 80°C. This parameter selection creates an optimal balance: the temperature is high enough to prevent premature film formation during application and handling, ensuring proper ink flow and adhesion, yet low enough to allow relatively fast drying compared to resins with higher film formation temperatures. The controlled parameter range resolves the contradiction by finding the optimal point where drying speed is sufficient for productivity but film formation timing is controlled for quality.
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 prevents ink repelling and blotting, enhances image quality by improving wettability and adhesion, and maintains the integrity of the recording medium, particularly on plastic sheets.
Implementation Method 1
The first drying portion is arranged downstream of the application portion with respect to the conveyance direction of the recoding medium and dries the white ink applied to the recoding medium by the application portion
Implementation Method 2
The second drying portion is arranged downstream of the recording portion with respect to the conveyance direction of the recoding medium and dries the non-white ink applied to the recoding medium by the recording portion
Implementation Method 3
The white ink contains first resin particles with a minimum film formation temperature of 40° C. or more but 80° C. or less. The non-white ink contains second resin particles with a minimum film formation temperature of 80° C. or less
Data Source
AI summary
An inkjet recording apparatus at least includes a conveyance portion, an application portion, a first drying portion, a recording portion, and a second drying portion. The first drying portion dries white ink applied to a recoding medium by the application portion. The recording portion ejects non-white ink onto the recording medium having passed through the first drying portion. The second drying portion dries the non-white ink applied to the recoding medium by the recording portion. The white ink contains first resin particles with a first minimum film formation temperature of 40° C. to 80° C. The non-white ink contains second resin particles with a second minimum film formation temperature of 80° C. or less. The drying temperature is, in the first drying portion, lower than the first minimum film formation temperature and, in the second drying portion, equal to or higher than the first and second minimum film formation temperatures.