Microwave Ink Drying for Stable Jetting on Heat-Sensitive Substrates
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Solution Overview
Problem
Conventional image forming methods face a trade-off between high-speed drying and ejection stability of ink, often causing damage to the base material due to uneven drying properties and microwave absorptivity differences among ink colors and resin types.
Innovation Solution
The method involves controlling the complex dielectric constants and drying rates of first and second inks within specific ranges, using microwaves to selectively dry the inks without heating the base material, ensuring uniform drying and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional heating methods (hot air or infrared heater) are used to dry the ink, then the base material is not damaged, but the drying speed is insufficient and printing speed must be reduced
Solution Approach 1:
The patent replaces conventional thermal conduction and convection heating methods with microwave radiation heating. The microwave heating unit directly heats the ink through dielectric heating without heating the base material, achieving high-speed drying while preventing base material damage. This substitution of heating mechanism resolves the contradiction between drying speed and base material protection.
Solution Approach 2:
The patent applies local quality by selectively heating only the ink layer while leaving the base material unaffected. The microwave heating unit is positioned to irradiate only the ink coating on the flexible packaging, creating a localized heating effect that dries the ink without transferring excessive heat to the base material, thus enabling high-speed drying without damage.
2Reliability
If a large amount of moisturizer with high boiling point is added to the ink to improve ejection stability, then ejection stability is improved, but more heat is required for drying and drying time must be extended
Solution Approach 1:
The patent replaces conventional slow thermal drying with rapid microwave heating. The microwave heating unit directly energizes the moisturizer molecules through dielectric heating, enabling rapid evaporation of the high-boiling-point moisturizer without requiring extended drying time. This allows the ink to contain sufficient moisturizer for ejection stability while achieving fast drying speeds.
Solution Approach 2:
The patent changes the heating parameter from conventional low-intensity thermal heating to high-intensity microwave heating. This parameter change enables the rapid removal of moisture and high-boiling-point moisturizer from the ink without compromising ejection stability, thus resolving the time-loss contradiction.
3Productivity
If microwaves are used to heat and dry the entire ink without controlling dielectric constant, then high-speed drying is achieved, but uneven drying occurs due to differences in microwave absorptivity among ink colors and resin types
Solution Approach 1:
The patent controls the dielectric constant parameter of the ink to optimize microwave absorption characteristics. By adjusting the ink composition to achieve a dielectric constant within a specific range, the ink exhibits uniform microwave absorptivity across different colors and resin types, enabling even high-speed drying without localized overheating or uneven drying.
Solution Approach 2:
The patent achieves homogeneity in microwave absorption by formulating the ink with uniform dielectric properties. The ink composition is designed so that all components (different colors and resin types) exhibit similar microwave absorptivity, ensuring uniform heating and drying across the entire ink layer without localized variations.
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 achieves high-speed drying and ejection stability without damaging the base material, preventing surface roughness and ink adhesion issues, resulting in high-quality images.
Implementation Method 1
The method of irradiating with microwaves is a method of heating an object to be dried by allowing microwaves to directly act on only a substance having a microwave absorptivity
Data Source
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Figure 3~4
AI summary
The present invention addresses the problem of providing an image forming method and an image forming system that can achieve both rapid drying and injection stability of ink, and that do not damage a base material. This image forming method is characterized by comprising a step of discharging and applying, onto a base material, a first ink and a second ink containing at least one of a pigment, an inorganic particle, an organic particle and a resin, water, and a water-soluble solvent, and at least one drying step of drying a coating film by microwave irradiation, wherein a complex dielectric constant ε"2 of the second ink at a drying rate of 95% is larger than a complex dielectric constant ε"1 of the first ink at a drying rate of 95%, and a drying rate D1 when the first ink is dried at 80°C for 20 seconds is larger than a drying rate D2 when the second ink is dried at 80°C for 20 seconds.