Inkjet Printing With UV Absorbent Heating to Prevent Ink Bleeding
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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 fabrics.
Innovation Solution
Incorporating an ultraviolet absorbent into the ink and using ultraviolet light to heat the ink to a temperature below its boiling point, effectively evaporating the solvent without boiling the ink, thus preventing bleeding and maintaining surface glossiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high heating temperature is used to prevent ink bleeding, then ink bleeding is suppressed, but ink may boil and generate bubbles causing surface unevenness and loss of glossiness
Solution Approach 1:
The patent changes the heating parameter from conventional high-temperature heating to controlled temperature heating (below boiling point), combined with ultraviolet irradiation to achieve ink fixation without surface degradation
Solution Approach 2:
The patent introduces ultraviolet light as an intermediary energy source to heat the ink through ultraviolet absorbents, rather than direct thermal conduction, enabling precise energy delivery that prevents bulk heating and surface damage
2Reliability
If high heating temperature is used to prevent ink bleeding, then ink bleeding is suppressed, but thermal impact may clog inkjet head nozzles
Solution Approach 1:
Ultraviolet light acts as an intermediary heating mechanism that selectively heats the ink on the medium without significantly heating the inkjet head nozzles, preventing thermal clogging while achieving ink fixation
Solution Approach 2:
The heating process is segmented into two independent mechanisms: ultraviolet irradiation for ink heating and conventional heating for medium heating, allowing separate optimization of each process to avoid nozzle clogging
3Productivity
If higher printing speed is used, then productivity is improved, but amount of ink per unit area increases leading to higher bleeding risk
Solution Approach 1:
The patent implements continuous ultraviolet irradiation during the printing process to continuously evaporate solvent from the ink, maintaining ink stability even at high printing speeds where ink accumulation occurs
Solution Approach 2:
The patent applies ultraviolet irradiation immediately after ink ejection to pre-evaporate solvent before the ink can spread and bleed, preventing bleeding proactively rather than reactively
4Reliability
If low-boiling solvent is used in ink, then evaporation is easier and bleeding is reduced, but solvent may evaporate in nozzles causing clogging
Solution Approach 1:
Ultraviolet light serves as a selective heating intermediary that targets only the ink on the medium through ultraviolet absorbents, leaving the ink in the nozzles unaffected and preventing premature evaporation and clogging
Solution Approach 2:
The heating effect is localized to the ink on the printed medium through selective ultraviolet absorption, while the ink in the nozzles remains at ambient temperature, creating different thermal conditions in different locations
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, reducing the risk of nozzle clogging and allowing for higher printing speeds without compromising the quality of the printed matter.
Implementation Method 1
Incorporating an ultraviolet absorbent into the ink and using ultraviolet light to heat the ink
Implementation Method 2
effectively evaporating the solvent without boiling the ink
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
A printing apparatus (10) is provided that effectively prevents the risk of ink bleeding so as to obtain a high-quality print result. The printing apparatus (10) includes an inkjet head (102) that ejects droplets of ink using inkjet technique so as to adhere the ink to the medium (50), and an ultraviolet light source (104) 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 (104) irradiates the ink adhered to the medium (50) 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.