Inkjet Precoating Pre-Drying for White Ink Transfer Prevention
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Solution Overview
Problem
Inkjet image forming apparatuses face challenges with the adhesion of white ink on smooth printing base materials due to insufficient drying, leading to ink transfer between stacked sheets, exacerbated by the use of precoating liquids that contain solvents.
Innovation Solution
The apparatus includes a precoating unit and a pre-drying part to apply and partially dry a precoating liquid before ink ejection, with controlled drying levels based on the presence of white ink, ensuring adequate solvent evaporation and improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ejection amount of white ink is increased to improve adhesion, then the adhesion of white ink is improved, but the solvent cannot be sufficiently dried, causing ink transfer to the rear surface of stacked printing base materials
Solution Approach 1:
The patent applies a precoating liquid to the printing base material before ink ejection and performs preliminary drying of the precoating liquid. This preliminary action creates a drier surface that prevents ink transfer while maintaining adhesion, resolving the contradiction between improving adhesion and ensuring complete drying.
Solution Approach 2:
The patent changes the drying parameters by introducing a pre-drying process with controlled drying conditions. By adjusting drying temperature, time, and airflow parameters during the pre-drying stage, the system achieves optimal drying completeness without compromising adhesion, even when white ink ejection amount is increased.
2Strength
If precoating treatment is performed to improve adhesion, then the adhesion of ink is improved, but the solvent in the precoating liquid reduces overall dryness, exacerbating ink transfer issues
Solution Approach 1:
The patent segments the drying process into two distinct stages: pre-drying of the precoating liquid before ink ejection, and main drying after ink ejection. This segmentation allows the pre-drying stage to remove excess solvent from the precoating liquid, reducing overall moisture content while maintaining the adhesion benefits of the precoating treatment.
Solution Approach 2:
The pre-drying process is performed as a preliminary action before ink ejection, removing the solvent contained in the precoating liquid. This preliminary solvent removal ensures that when ink is ejected, the substrate has reduced moisture content, preventing ink transfer while preserving the adhesion enhancement from the precoating treatment.
3Reliability
If a pre-drying process is introduced to control solvent content, then drying completeness is improved, but the device complexity increases
Solution Approach 1:
The patent merges the pre-drying function with the existing inkjet image forming apparatus structure, integrating the pre-drying process into the conventional workflow. By combining the precoating unit and pre-drying part into a unified system that operates sequentially with the image forming part, the patent achieves improved drying completeness without proportionally increasing device complexity.
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
Enhances ink adhesion and prevents ink transfer by optimizing the drying process, maintaining the precoating effect while ensuring complete drying of the solvent, particularly for white ink applications.
Implementation Method 1
a pre-drying part arranged on a downstream side of the precoating unit in the conveyance direction, and configured to pre-dry the precoating liquid ejected on the printing base material before the inks are ejected in the image forming part
Data Source
AI summary
An inkjet image forming apparatus includes an image forming part, a precoating unit, a pre-drying part, and a control part. The precoating unit is arranged on an upstream side of the image forming part. The pre-drying part is arranged on a downstream side of the precoating unit, and pre-dries the precoating liquid ejected on the printing base material before the inks are ejected in the image forming part. The control part controls the pre-drying part so that W1<W2, where W1 (g/m2) is an amount of the pre-coating liquid ejected to the printing base material conveyed to the image forming part when a print job for ejecting the white ink is performed, and W2 (g/m2) is an amount of the pre-coating liquid ejected to the printing base material conveyed to the image forming part when a print job for not ejecting the white ink is performed.