Inkjet Printing Ink Receiving Layer on Plastic Moldings
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Solution Overview
Problem
Inkjet printing on plastic molded articles, such as caps, faces challenges due to solvent-based ink receiving layers, which require high-temperature drying, leading to substrate deformation and reduced productivity, especially with thermoplastic resins like polyolefin.
Innovation Solution
An inkjet printing method using an oil-based ink with inorganic fine particles and a wet type resin, where the ink receiving layer is formed by inkjet printing, allowing for mild solvent removal and selective application, reducing material costs and increasing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a solvent-based ink receiving layer is coated on the plastic molded article surface, then ink bleeding is prevented and image quality is improved, but high-temperature drying causes substrate deformation and productivity decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the ink receiving layer by using a water-based slurry containing inorganic fine particles and specific polymers instead of traditional solvent-based coatings. This allows the layer to be dried at low temperatures (room temperature or slightly elevated), preventing substrate deformation while maintaining ink-receiving functionality and image quality
Solution Approach 2:
The patent introduces a water-based slurry as an intermediary medium that carries inorganic fine particles and polymer components to form the ink receiving layer. This slurry system enables low-temperature processing compared to traditional solvent-based systems, resolving the contradiction between image quality and productivity
2Loss of time
If high-temperature heating is applied to remove solvent from the ink receiving layer, then drying time is shortened, but the plastic substrate deforms
Solution Approach 1:
The patent fundamentally changes the drying temperature parameter by using a water-based formulation instead of solvent-based. The ink receiving layer can be dried at room temperature or slightly elevated temperatures (e.g., 40-60°C), which is sufficient to evaporate water and bind the inorganic particles without causing plastic substrate deformation
Solution Approach 2:
The patent uses a water-based slurry formulation that is easier and cheaper to process than solvent-based systems. The water evaporates quickly at low temperatures, and any residual moisture can be removed without aggressive heating, thus protecting the substrate shape while maintaining productivity
3Manufacturing precision
If the ink receiving layer is formed by conventional coating methods, then complete coverage is achieved, but material cost and processing complexity increase
Solution Approach 1:
The patent replaces conventional mechanical coating systems (such as gravure printing, flexography, or spray coating) with an inkjet printing system. The ink receiving layer is deposited dropwise through inkjet nozzles, allowing precise placement of material only where needed, reducing material waste and simplifying the manufacturing process while achieving uniform coverage
Solution Approach 2:
The patent segments the ink receiving layer formation into discrete droplets deposited by inkjet printing. Each droplet is placed precisely at the required location, and the layer is built up incrementally. This segmented approach reduces material usage, lowers cost, and simplifies the manufacturing process compared to conventional coating methods that require complete surface coverage
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
Enables efficient inkjet printing on plastic caps with minimal solvent removal, preventing thermal deformation and allowing for high-speed image formation with reduced material usage and costs, while maintaining image quality.
Implementation Method 1
the wet type resin is one in which an increase in volume is observed due to penetration of the solvent when immersed at 25°C in the solvent contained in the oil-based ink
Implementation Method 2
forming a printed image by flying ink droplets by means of a nozzle head and depositing them on a predetermined recording medium
Data Source
Figure 1~2
Figure 3
AI summary
The present invention is a printing method for forming an inkjet-printed image 3 on the surface of a molded article 1, characterized by: forming an ink receiving layer 5 on a portion, where the printed image 3 is to be formed, by inkjet printing in correspondence with the printed image 3 prior to formation of the printed image 3 with an inkjet using an oil-based ink. This method can form the inkjet-printed image efficiently on the surface of the molded article 1.