UV Absorbent Inkjet Ink for Bleeding Prevention
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Solution Overview
Problem
Conventional inkjet printing methods using evaporation drying inks face challenges such as ink bleeding, nozzle clogging, and poor printing quality due to high heating temperatures, especially at higher printing speeds and with fabric mediums, which require pretreatment and result in increased costs and time.
Innovation Solution
Incorporating an ultraviolet absorbent into the evaporation drying ink to allow for efficient drying under ultraviolet radiation, reducing the risk of ink bleeding and nozzle clogging, while maintaining printing quality by volatilizing solvents without overheating the inkjet head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the medium is heated at high temperatures to prevent ink bleeding, then ink bleeding is prevented, but the nozzle surface of the inkjet head may be heated and nozzles may be clogged
Solution Approach 1:
The heating process is segmented into two distinct stages: (1) UV irradiation heating that rapidly heats only the ink layer to prevent bleeding, and (2) subsequent medium heating at lower temperatures to complete drying. This segmentation allows the ink to be heated to high temperatures briefly without heating the medium or nozzle to clogging levels.
Solution Approach 2:
UV irradiation is applied immediately after ink ejection as a preliminary action to rapidly evaporate the solvent and increase ink viscosity before the ink can bleed. This preliminary heating action prevents bleeding without requiring subsequent high-temperature medium heating that would cause nozzle clogging.
2Productivity
If printing speed is increased, then productivity is improved, but the amount of ink landing on the medium per unit area increases and ink bleeding becomes more likely
Solution Approach 1:
UV irradiation is applied immediately after ink ejection as a preliminary action to rapidly evaporate the solvent and increase ink viscosity before the ink can bleed. This preliminary heating action prevents bleeding without requiring subsequent high-temperature medium heating that would cause nozzle clogging.
3Ease of manufacture
If fabric medium is used without pretreatment, then cost and time are reduced, but ink bleeding occurs
Solution Approach 1:
The conventional mechanical/chemical pretreatment process is replaced by UV irradiation heating. The UV energy directly heats the ink and evaporates the solvent, creating a bleeding-prevention effect without requiring any pretreatment layers or chemical agents on the fabric medium.
Solution Approach 2:
The ink itself serves the dual function of being the print material and the medium for UV absorption. By incorporating UV absorbent components into the ink formulation, the ink absorbs UV energy and converts it to heat, enabling self-heating and solvent evaporation without external heating elements or pretreatment layers.
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 method effectively prevents ink bleeding, ensures high-quality prints, and allows for higher printing speeds without the need for pretreatment on various mediums, reducing costs and time, while maintaining inkjet head stability.
Implementation Method 1
droplets of ink containing at least an ultraviolet absorbent are ejected to a medium, and the ink is heated by ultraviolet radiation
Implementation Method 2
the ink is heated by a heater and dried to be prevented from bleeding
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
To suppress the risk of ink bleeding and thereby attain an improved printing quality, a printing apparatus 10 is provided that carries out an inkjet printing operation for a medium 50. The printing apparatus 10 includes inkjet heads 102 that eject droplets of ink using inkjet technique; and ultraviolet light sources 104 that radiate ultraviolet light. The ink ejected from the inkjet heads 102 contains an ultraviolet absorbent that absorbs ultraviolet light, and a solvent that dissolves or disperses the ultraviolet absorbent. The ejected ink is adherable to the medium 50 and fixable by evaporating the solvent. The ultraviolet light sources 104 irradiate the ink adhered to the medium 50 with ultraviolet light so as to volatilize and remove at least part of the solvent from the ink.