introductory:
In today's printing industry, with the continuous improvement of the market's requirements for print quality, production efficiency and environmental protection, offset UV ink came into being. Traditional inks have certain limitations in terms of drying speed, color expression and environmental performance, while offset UV inks can meet the needs of high-quality and high-efficiency printing in many fields such as packaging, labeling, and commercial printing with their unique advantages.
1. Ink characteristics
Fast curing
Under ultraviolet irradiation, curing can be completed in a short time, and the curing speed can reach several meters per second, which greatly improves production efficiency, reduces the drying waiting time of printed matter, and is suitable for high-speed printing production lines.
High gloss
The cured ink film has excellent gloss, usually up to 80 - 95 GU (depending on different standards and test conditions), which can make the printed matter present a bright, high-end appearance and enhance the visual appeal of the product.
Excellent color performance
The selection of high-quality pigments, with high color saturation and accurate hue, wide color gamut, can accurately restore a variety of colors, to meet the printing needs of high color requirements, such as exquisite albums, high-end packaging, etc.
Good abrasion and chemical resistance
The cured ink film has high hardness, strong abrasion resistance, and can effectively resist friction and scratching in daily use; At the same time, it has good resistance to common chemicals such as solvents, acids and alkalis, etc., to ensure the color stability and pattern integrity of printed matter in different environments.
Low VOC emission
Almost no volatile organic compounds (VOCs), no harmful gases will be released into the air during the printing process, in line with environmental protection requirements, conducive to improving the working environment and reducing pollution to the atmosphere.
2. Technical parameters
Curing wavelengths
The main absorption wavelengths range from 365 to 405nm, which match the emission wavelengths of common UV curing equipment to ensure that the ink can cure quickly and sufficiently.
Viscosity
Under the condition of 25°C, the viscosity is usually controlled between 10 - 30Pa·s, which has good printability, can be smoothly transferred during the printing process, and ensures the uniform distribution of the ink layer.
Adhesion fastness
Through the 100 grid test, the adhesion level reaches 0 - 1 level, which ensures that there is a strong bond between the ink and the printed material, and it is not easy to fall off.
Lightfastness
After a long time of light test, the color change ΔE≤3 indicates that the ink has good lightfastness, and the printed matter is not easy to fade under sunlight or strong light.
3. Application scenarios
Packaging and printing
Suitable for all kinds of high-end packaging boxes, gift boxes, cosmetics packaging, etc., can give the packaging exquisite appearance and good protective performance, and enhance product grade and brand image.
Label printing
In the field of label printing, UV ink has the characteristics of fast curing speed and strong adhesion, making it very suitable for labels of various materials, such as paper labels, plastic film labels, etc., which can ensure that the label pattern is clear and durable.
Commercial printing
For commercial printing such as posters, brochures, samples and other commercial prints, the high gloss and excellent color performance of UV ink can attract consumers' attention and enhance the effect of advertising.
4. Ink selection
According to the printing material
For paper, ordinary coated paper can choose general-purpose offset UV ink to show its high gloss and color advantages; For coarse papers, UV inks with good hiding power and adhesion can be selected. In terms of plastic film printing, for different materials such as PET and PVC, it is necessary to choose a special UV ink to ensure the adhesion between the ink and the film and the printing effect.
Combined printing process
Choose the appropriate UV ink according to the type of printing machine and the requirements of the printing process. For example, waterless offset printing should choose a special waterless offset UV ink to adapt to the special environment of waterless printing; For conventional water-based offset printing, ordinary offset UV ink can be used.
5. Pre-printing preparation
Equipment cleaning and commissioning
Thoroughly clean the ink fountain, ink roller, rubber cloth and other parts of the printing machine to prevent impurities from affecting ink transfer and printing quality. Debug the printing pressure, water-ink balance (if there is water offset printing) and other parameters to ensure that the equipment is in the best working condition.
Ink preparation
Accurately mix ink according to the color requirements of the printing order. Use ink stirring equipment to fully stir to evenly disperse pigments and additives to avoid precipitation and affect the performance and printing effect of ink.
Printing material testing
Check the flatness, thickness uniformity, surface roughness and other indicators of the paper, as well as the surface tension, thickness tolerance and other parameters of the plastic film to ensure that the printed materials meet the printing requirements and avoid problems such as poor ink adhesion and color deviation caused by material problems.
6. Printing process control
Printing pressure control
According to the thickness and hardness of the printed material, the printing pressure is accurately adjusted to ensure the uniform transfer of ink. Excessive pressure can lead to dot expansion and ink build-up; If the pressure is too low, the ink will be transferred under, which will affect the printing quality and gloss.
UV curing control
Adjust the power, irradiation time and distance of the UV curing lamp to ensure that the ink can be fully cured. Insufficient curing will lead to sticky ink and poor abrasion resistance; Over-curing can cause the ink film to become brittle and yellow, affecting the quality and appearance of the printed product.
Color management
During the printing process, the color management system is used to monitor and adjust the printed color in real time to ensure that the color of the printed matter is consistent with the standard color sample and meets the color requirements of customers.
7. Quality inspection
Curing effect detection
By scratching the surface of the printed matter with a fingernail or hard object, check whether the ink film is completely cured, whether there is any falling off, scratching and other phenomena. You can also use professional curing testing instruments, such as energy meters, to detect whether the energy output of UV curing lamps meets the requirements of ink curing.
Gloss detection
Use the gloss meter to measure the gloss at different positions of the printed matter, and compare it with the standard value to ensure that the gloss meets the requirements and the deviation is controlled within ±5GU.
Color detection
The color data of the printed matter is measured by spectrophotometer, and compared with the standard color sample, the color deviation ΔE is controlled within 3 to ensure the accuracy of the color.
Printing quality inspection: check the clarity and uniformity of the dots of the printed matter through visual inspection or with the help of a magnifying glass, and whether there are defects such as ghosting, pasting, and missing printing, so as to ensure that the printing quality meets the standards.
8. Storage & Transportation
Storage
Store offset UV inks in a cool, dry, well-ventilated warehouse, away from direct sunlight and high temperatures. The storage temperature is generally controlled between 5 - 25°C, and the relative humidity is maintained at 40% - 70%. The ink should be sealed and stored to prevent solvent volatilization and moisture ingress, regularly check the status of the ink, and deal with it in time if precipitation, crusting and other phenomena are found.
Transportation
During transportation, special transportation tools are used to avoid collisions, squeezing and rain on the ink. When loading and unloading, it should be handled with care to prevent the packaging from being damaged. At the same time, it is necessary to pay attention to controlling the temperature and humidity of the transportation environment to ensure that the quality of the ink is not affected.
9.Precautions
Operator protection
Operators should wear personal protective equipment such as protective gloves, masks, and goggles to avoid skin contact and inhalation of volatile components in the ink. The workplace should maintain good ventilation conditions and reduce the concentration of harmful gases.
Ink use management
Follow the principle of first-in, first-out, and use in strict accordance with the shelf life of ink. For expired inks, they should be tested, and if the performance meets the requirements, they can continue to be used; If it does not meet the requirements, it should be properly handled in accordance with the relevant regulations.
Environmental management
The printing workshop should be kept clean and the ink residue and waste should be cleaned regularly. For the wastewater and waste gas containing ink, it should be discharged after treatment to meet the standard to reduce environmental pollution.
10. Recommendation of the same type of products
Ordinary Economical Offset Ink