UV-Heated Inkjet Printing to Prevent Bleeding and Gloss Loss
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Solution Overview
Problem
Inkjet printing with evaporation-drying inks faces issues such as ink bleeding, surface unevenness, and nozzle clogging due to high heating temperatures, especially at higher printing speeds and with latex inks, which can lead to curling or cockling of paper mediums and require specialized pretreatment for fabric mediums.
Innovation Solution
Incorporating an ultraviolet absorbent into the ink and using ultraviolet light to heat the ink below its boiling point, allowing for efficient solvent evaporation without boiling, thus preventing ink bleeding and maintaining surface glossiness, while also reducing the risk of nozzle clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the medium is heated at high temperatures to prevent ink bleeding, then ink bleeding is suppressed, but the ink may boil and generate bubbles causing surface unevenness and loss of glossiness
Solution Approach 1:
The patent changes the heating parameter from high temperature to controlled low temperature (below boiling point), and introduces ultraviolet irradiation as an additional drying mechanism to compensate for the reduced thermal drying efficiency, thereby preventing ink bleeding while maintaining surface glossiness
Solution Approach 2:
The patent replaces part of the thermal drying mechanism with ultraviolet irradiation. The ultraviolet light source irradiates the ink to promote solvent evaporation and ink drying without requiring high temperatures, thus avoiding ink boiling and surface unevenness while still preventing ink bleeding
2Productivity
If printing speed is increased to improve productivity, then more ink lands on the medium per unit time, but the likelihood of ink bleeding increases
Solution Approach 1:
The patent introduces ultraviolet irradiation that acts continuously and immediately on the ink after ejection, providing continuous drying action that keeps pace with increased printing speeds. This ensures that even when more ink lands on the medium per unit time, the ultraviolet light continuously promotes solvent evaporation and prevents ink bleeding
Solution Approach 2:
The patent replaces the thermal drying mechanism with ultraviolet irradiation, which provides more rapid and controllable ink drying. This substitution enables the system to handle higher printing speeds and greater ink deposition rates without increasing ink bleeding, as ultraviolet irradiation can be precisely controlled and acts immediately on the ink
3Ease of manufacture
If evaporation-drying ink is used to simplify the printing process, then specialized pretreatment is eliminated, but the ink is more likely to bleed compared to other ink types
Solution Approach 1:
The patent replaces the thermal drying mechanism with ultraviolet irradiation, which provides rapid and effective ink drying without requiring high temperatures. This substitution enables the use of evaporation-drying ink on various mediums without specialized pretreatment while effectively preventing ink bleeding, as the ultraviolet light rapidly promotes solvent evaporation before the ink can bleed
Solution Approach 2:
The patent changes the drying mechanism from thermal to ultraviolet-based, and controls the temperature to below the boiling point of the ink. This parameter change enables effective ink drying and bleeding prevention without requiring specialized medium pretreatment, maintaining the simplicity of the printing process while improving ink bleeding resistance
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
The method effectively prevents ink bleeding and maintains the glossiness of printed surfaces, even at higher printing speeds, and allows for printing on various mediums without the need for pretreatment, enhancing printing efficiency and quality.
Implementation Method 1
The ink is irradiated with ultraviolet light from a light source and is thereby heated to a temperature lower than a boiling point of the ink and high enough to prevent the ink from bleeding
Implementation Method 2
heating the ink to a temperature lower than a boiling point of the ink and high enough to prevent the ink from bleeding, so that a solvent included in the ink is at least in part volatilized and removed
Data Source
AI summary
A printing apparatus is provided that effectively prevents the risk of ink bleeding so as to obtain a high-quality print result. The printing apparatus includes an inkjet head that ejects droplets of ink using inkjet technique so as to adhere the ink to the medium, and an ultraviolet light source that radiates ultraviolet light. The ink contains a colorant, an ultraviolet absorbent, a resin, and an aqueous solvent that emulsifies or suspends the resin. The ultraviolet light source irradiates the ink adhered to the medium with ultraviolet light to heat the ink to a temperature lower than a boiling point of the ink and high enough to prevent the ink from bleeding, so that the aqueous solvent is at least in part volatilized and removed from the ink.