Inkjet Printing on Coated Paper via Polymer Aggregation and Drying
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Solution Overview
Problem
Current direct printing methods using inkjet recording apparatuses face challenges in achieving high image quality with minimal landing interference, image contraction, and curl prevention, especially when using coated papers, which are prone to liquid absorption issues and curling.
Innovation Solution
The method involves using a special paper with a laminated structure and a specific aqueous ink composition, including a resin dispersant, self-dispersible polymer micro-particles, and a drying unit to prevent solvent infiltration and promote rapid ink drying, while maintaining ink stability and dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct printing method is used to simplify the apparatus structure, then device complexity is reduced, but image quality deteriorates due to landing interference and image contraction
Solution Approach 1:
The patent segments the ink composition into distinct functional components: water-soluble polymer micro-particles for aggregation, pigment particles for color, and aqueous solvent. This segmentation allows each component to perform its specific function optimally, enabling direct printing to achieve image quality comparable to indirect methods while maintaining apparatus simplicity.
Solution Approach 2:
The patent changes the physical and chemical parameters of the ink system by controlling the molecular weight, glass transition temperature, and composition ratios of the water-soluble polymer. These parameter changes enable the ink to aggregate rapidly upon contact with the recording medium, preventing landing interference and image contraction in direct printing.
2Object-affected harmful factors
If aqueous ink is used to improve environmental suitability, then environmental compatibility is improved, but recording medium deformation worsens due to water permeation and curling
Solution Approach 1:
The patent utilizes phase transition by incorporating water-soluble polymer micro-particles that undergo aggregation when exposed to the recording medium environment. This phase change from dispersed to aggregated state occurs rapidly, forming a stable ink aggregate that prevents excessive water penetration into the recording medium, thereby reducing curling and deformation while maintaining environmental suitability of aqueous ink.
3Manufacturing precision
If ink aggregation is enhanced to improve image quality, then text reproducibility is improved, but ink stability before ejection worsens due to premature aggregation
Solution Approach 1:
The patent uses water-soluble polymer micro-particles as an intermediary between the pigment and the recording medium. These micro-particles remain stably dispersed in the aqueous ink during storage and ejection, then act as aggregation nuclei upon contact with the recording medium, enabling controlled aggregation that improves text reproducibility without compromising ink stability before ejection.
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 enables high-quality image formation with reduced landing interference, image contraction, and curl prevention, ensuring good text reproducibility and stability in direct printing on coated papers.
Implementation Method 1
a water-soluble polymer micro-particles (C) and an aqueous liquid medium (D)... capable of swelling, increasing in viscosity and separating by reaction with the ink
Implementation Method 2
a drying unit arranged on a downstream side of the image formation unit, the drying unit having a drying device disposed opposite a circumferential surface of a drying drum, the drying device drying a solvent in the aqueous ink deposited on the recording medium
Data Source
AI summary
The method forms an image using an inkjet recording apparatus, which includes: an image formation unit having a line head type inkjet head disposed opposite a circumferential surface of an image formation drum, the inkjet head depositing the aqueous ink onto the recording medium while the recording medium is held and conveyed in rotation on the circumferential surface of the image formation drum; and a drying unit arranged on a downstream side of the image formation unit, the drying unit having a drying device disposed opposite a circumferential surface of a drying drum, the drying device drying a solvent in the aqueous ink deposited on the recording medium, the drying unit drying the solvent by means of the drying device while the recording medium is held and conveyed in rotation on the circumferential surface of the drying drum; using, as the recording medium, a special paper which is a recording medium successively laminated from a base paper, a first layer containing a binder and a second layer containing a white pigment, the base paper with the first layer provided thereon having a Cobb water absorbency of not higher than 5.0 g/m2 with a contact time of 15 seconds based on a water absorbency test stipulated in JIS P8140, and the second layer having a water absorption amount of not lower than 2 ml/m2 and not higher than 8 ml/m2 with a contact time of 0.5 seconds according to Bristow's method, and having a layer surface pH of not higher than 5.5 after pH adjustment.