The problems of UV flexographic ink in the printing process
Date: Sep 30 2024 From: Star Color
UV flexographic ink, as an efficient and environmentally friendly printing material, has been widely used in the modern printing industry. In the printing process of UV flexographic ink, a series of problems may also be encountered, which may affect the printing quality and efficiency. We will have a detailed discussion on these issues.
Wire drawing and pasting phenomenon
Problem description:
If the viscosity of UV flexographic ink is low during the printing process, it is easy to cause wire drawing and plate sticking. This can cause uneven color distribution and even poor adhesion in printed materials, seriously affecting printing quality.
Solution:
Improving ink viscosity: Adding an appropriate amount of resin can increase the viscosity of UV flexographic ink and enhance the adhesion of printed materials.
Printing plate cleaning: Before printing, the printing plate should be thoroughly cleaned to avoid the influence of residues on ink viscosity.
Drying speed too fast
Problem description:
The drying speed of UV flexographic ink is too fast, which can cause the color of printed materials to become lighter. This is usually caused by UV lamp power being too high or printing speed being too fast.
Solution:
Adjust UV lamp power: Reduce the power of the UV lamp or decrease the printing speed to slow down the drying speed.
Adding additives: Adding an appropriate amount of additives to the ink can also slow down the drying speed and improve the color saturation of printed materials.
Bubble problem
Problem description:
UV flexographic ink may produce bubbles during the printing process, mainly due to excessive surface tension of the ink.
Solution:
Add defoamer: Add an appropriate amount of defoamer to the ink to reduce its surface tension and avoid the formation of bubbles.
Printing plate cleaning: It is also necessary to ensure the cleanliness of the printing plate to avoid the influence of residues on the surface tension of the ink.
Poor adhesion and color fading
Problem description:
The poor adhesion and easy color fading of UV flexographic ink printed products are usually caused by insufficient ink curing.
Solution:
Improve curing effect: Increase the power of the UV lamp or extend the curing time to ensure that the ink is fully cured.
Increase ink usage: Apply a layer of reinforcing liquid or increase the amount of ink on the surface of the printed material to improve adhesion.
Choose the appropriate ink: Select the suitable UV flexographic ink based on the material and requirements of the printed material.
Printing stability issues
Problem description:
In the UV flexographic printing process, printing stability is also an aspect that cannot be ignored. Ink emulsification, changes in workshop temperature and humidity, cleaning and maintenance of UV lamps and reflectors can all affect printing quality.
Solution:
Control ink balance: During the printing process, it is necessary to control the ink balance well, avoid ink emulsification, and ensure the transmittance of ultraviolet light.
Control workshop temperature and humidity: Control the workshop temperature at 20-25 ℃ and relative humidity at 50% -65% to ensure stable performance of ink and substrate.
Regular cleaning and maintenance: Regularly clean the UV lamp tube and reflector cover to ensure they are clean, bright, and have the best reflection effect.
Ink storage and management
Problem description:
The storage conditions of UV flexographic ink are also a key factor affecting its quality of use. Improper storage may cause ink to deteriorate and affect printing quality.
Solution:
Control storage conditions: The optimal storage temperature for UV flexographic ink should be controlled at 20-25 ℃, relative humidity should be controlled at 55% -65%, and sealed for storage to prevent dust from entering.
Following the principle of "first in, first out": ink purchased first should be used first to prevent prolonged storage time from affecting its quality of use.
Remaining ink treatment: The remaining ink after printing must be sealed and stored in a dark place, and used as soon as possible, with a maximum storage period of no more than one year.
Substrate pretreatment
Problem description:
The surface condition of the substrate has a significant impact on the adhesion of UV flexographic ink. If the surface tension of the substrate is low or there are impurities, it will affect the adhesion effect of the ink.
Solution:
Surface treatment: Surface treatment of the substrate, such as flame treatment or corona treatment, to increase its surface activity and improve adhesion.
Cleaning the substrate: Use a cleaning cloth dipped in alcohol or isopropanol to clean the surface of the substrate to remove impure chemicals and impurities.
Printing color sequence and pressure adjustment
Problem description:
In the UV flexographic printing process, the arrangement of printing color sequence and the adjustment of printing pressure can also affect the printing quality. Improper color sequence or insufficient pressure can lead to color mixing or uneven color distribution.
Solution:
Reasonably arrange color sequence: Change the color sequence appropriately according to the ink volume of the printed pattern to avoid color mixing.
Adjust printing pressure: Adjust the pressure between the rubber cylinder and the plate cylinder to within the standard pressure, and use UV printing special rubber blanket and gripper teeth.
summary
UV flexographic ink may encounter various problems during the printing process, but these problems can be effectively solved through reasonable solutions and strict process control. Printing enterprises should strengthen their understanding and management of UV flexographic ink, fully leverage its advantages of high efficiency and environmental protection, and make greater contributions to the development of the printing industry.
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