With paper Compared with printing , transparent plastic box printing needs to confirm the color of the printing proof. This is because the quality of the color of the transparent plastic box printing directly affects the quality of the mass production of the transparent plastic box. For many years, the author has been engaged in pre-press production management in plastic box printing enterprises, and has accumulated some experience in color control of transparent plastic box printing proofing. I would like to share it with you.
Guaranteed white ink printing effect
The transparent plastic box contrasts other colors by printing white ink. White ink usually consists of two colors, one is yellowish warm white, and the other is bluish cool white (also known as "special white"). The PVC, APET, PP and other materials commonly used in transparent plastic boxes also have different colors. For example, PVC has white and blue chips. In transparent plastic box printing, white film should be printed with cool white ink, blue film should be Choose warm white ink for printing. Under normal circumstances, the transparent plastic box will also print the second white ink to support the bottom. It is recommended to use 80% white ink to overprint the solid white ink for better results.
Multi-color overprinting effect with UV curing unit
Transparent plastic box printing is divided into two ways: printing and printing. The white ink is printed first, followed by four colors or other special color overprints. It should be noted that after the transparent plastic box is printed with white ink, it must be UV-cured before overprinting. If you encounter non-white overprinting other colors (such as large solid blue overprinted large solid dark printing), when the ink transfer is poor, you should also add UV curing process between the two colors, the final printing effect will be significantly better than direct The effect of overprinting. In addition, the parameters of the UV curing unit during the printing of the transparent plastic box must be recorded to ensure the consistency of printing conditions in mass production.
Color standardization, dataization
Densitometers should be used to control color during clear box printing. Since the printing area is separated by a layer of substrate, the dot area ratio will be higher, and the dot gain rate will be 3% to 5% higher. Therefore, the measuring strip should be set at the end of the printing sheet to realize color standardization and dataization. Of course, the printing company should formulate reference data for printing density, dot gain rate and allowable color difference ΔE according to actual conditions. Table 1 is the relevant reference data for a printing company.
When testing the dot gain rate, you should pay attention to the dot data in the 0% to 20% area. It is recommended to test the 3%, 7%, 10%, and 15% dots respectively. This is because the complete dot gain rate is a parabola from 0% to 100%, and the dot gain is most severe at about 50% of the dots. However, after many years of use, the printing machine will produce data deviation, which results in different reduction rates of small dots, that is, small dots in the 0% to 20% region are most likely to be biased. In addition, CTP is also prone to loss of small dots when data is output. Therefore, it is especially important to control the normal restoration of the dot data in this area during printing proofing.
Guarantee color consistency
The box shape of the transparent plastic box is butt joint molding. When printing and proofing, the density meter should be used to measure and control the data of each ink key area to ensure the color consistency of all areas of the transparent plastic box, and avoid the color deviation after the transparent plastic box is formed. Asymmetric situation.
