Understanding of Domestic Printing Card UV Offset Machine (2)

1. UV ink

UV inks are light-curable absorbent inks, and since many cards require laminating, the performance of UV inks is particularly important. There are two key points: First, the need for high temperature, high pressure, in the laminator high temperature, high pressure does not change color, do not fade; Second, the bonding force with the plastic film to be large, the minimum standard required to reach 6N tension. In addition, the selection of UV ink for card printing is also quite critical. In addition to ensuring the quality of the ink itself, it must also match the wavelength of the UV lamp of the printer. Since many manufacturers use color inkjet printing as a manuscript for printing, it is recommended to select yellow, magenta, and cyan in the standard hue as far as possible when purchasing ink. In addition, when spot color inks are formulated, inks with low viscosity and good fluidity should be selected as far as possible. The European Ark ink is preferred.

2. Special printing plate

UV offset printing plate wear-resistant, resistant to printing, no need to protect the adhesive when the machine stops, the old version can be used again, and is very suitable for the transfer of UV ink, high reduction rate when printing, can basically reach 2% of the outlets Without losing, 98% of the outlets can be distinguished. The current Japanese version of Fuji UV is of better quality. Considering the cost of printing, the text version can be properly used for the short version of a batch with a normal version. However, the film is extremely fragile and must be printed with care.

3. Blanket and bag lining

In order to ensure the best transferability and dot reducibility of UV inks, it is best to use air-cushioned blankets, because they have good acid resistance, oil resistance, hydrophobicity, and good ink transfer performance, and can ensure that the dot distortion during the printing process is minimal. Printed graphics are clear, high-profile reproduction is good, and plate wear is low.

Eraser roller liner lining is better than neutral hard, because the surface of PVC and other sheets is rough, which can easily lead to high printing dot gain, and the use of neutral hard liner can make the dot clear, smooth and reproducible. The geometric shape of the graph changes little, and the increment of the width of the graphic and printed sheets is relatively small.

4. PVC and other sheets

Sheets such as PVC have a light surface and a matt surface, the light surface is flat. Rougher matte surface. Selecting the printing surface is very important and many print quality problems can be avoided. The matte side of the sheet such as PVC is usually used as the printing surface to ensure that the actual ink printing does not pull the hair, the network point is strong. The adhesion between the ink and the material is strong, and the ink is full and does not expose small white spots. In addition, the printing pressure is appropriately increased by 0.02 to 0.05 mm from the standard pressure.

5. Auxiliary materials

UV car wash used by the car wash water, blanket cleaning agent, cleaning fluid, etc. are best to use special products, which for the UV ink roller, UV blanket and UV printing plate is particularly important for the service life and performance. Although the cost will be higher, it can be flexibly applied according to the actual situation. Ensure that the ink roller is cleaned once a week: use a special revert agent to clean the blanket when it is stopped, which can not only ensure the elasticity of the blanket, but also guarantee the color balance and color difference when restarting. $Page break $

Printing adjustment

1. Workshop environment control

Maintain humidity at 50% to 60%, summer temperature at 20～22°C, winter temperature at 22～25°C, UV printing in offset printing workshop will generate a lot of heat, control temperature and humidity is to ensure printing quality primary condition.

2. Preparation of the fountain solution

At present, UV offset printing generally uses alcohol fountain solution or isopropyl alcohol fountain solution. In comparison, alcohol can be quickly volatilized, which can effectively transfer the heat generated by the printing plate running and the friction of the ink roller. It is recommended to use an alcohol fountain solution with a concentration of 10% to 12% and a temperature of 5 to 10°C.

Controlling the pH of fountain solution is particularly important, as large as possible to ensure that the pH at the dirty plate afford the premise, the pH of UV offset general control 5.6 ~ 6. Too acidic, can cause serious forum on dirty, graphic basis because of the erosion caused by the flower version, easily emulsified ink, ink roller easy to produce de-inked, printed ink dark and dull; acidity is too small, easy to make the ink forum Loss of balance, non-graphical part of the hydrophilic and oil-repellent weakened, the layout from the dirty, due to the increase in print outlets caused by paste version. Therefore, the control of the fountain solution pH plays a key role in printing.

3. Common printing failure

(1) Flying ink &n