Application skills of mirror ink in screen printing
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Mirror inks are printed on transparent plastic sheets, such as PC, PET, PVC, and PMMA, printed on the back of these transparent sheets, and appear from the front of the transparent sheet as smooth with a mirrored or bronzing surface. So it is called mirror ink. Mirror inks are widely used in the operation panels of washing machines, refrigerators, and microwave ovens. Currently, mirror inks are used in IMD technology, such as mobile phones, car dashboards, and various decorative instrument panels and panels. It can be seen that mirror ink has penetrated into many industries to add color to these products. However, compared with ordinary screen printing inks, mirror printing inks require high printing technology and must have certain printing experience and printing skills. The person prints according to the process parameters of the mirror ink, and can achieve a satisfactory mirror effect after silk screen printing. Here are some suggestions on how to screen the mirror ink:
First, the characteristics of the mirror ink:
1. Mirror ink is made up of special metal powder and resin as the basic material. After silk screen printing, it can achieve the metallic mirror effect. Since the ink is required to maintain maximum fluidity, the ink is added with a large amount of special solvent, so the viscosity of the mirror ink is very low, as low as water. Therefore, silk screen printing is difficult, and high-tech printing level printing is required. Otherwise, (1) When there is no printing, the mirror ink has leaked through the screen and is contaminated with the substrate. (2) In the printing process, the mirror ink is very easy to dry. In addition to blocking the net, the dry mirror ink is deposited on the net, which becomes “silver residue” and reduces the mirror effect of the printed matter.
2. The mirror ink utilizes the smoothness of the surface of the substrate material, so that the metal powder pigment in the printed ink is arranged in parallel on the surface of the flat substrate to obtain a mirror effect. Since the mirror ink has such a property, the material having poor surface flatness on the surface of the transparent substrate (transparent sheet) is not mirror-finished. (2) If the transparent substrate material cannot resist the solvent in the mirror ink, it will not get a good mirror effect. (3) After the mirror ink is screen printed, the mirror effect is related to the drying method. (4), silk screen operation skills will affect the mirror effect.
Second, the types of Japanese fine mirror inks and the range of applicable materials:
1, mirror silver B, only for printing PET film.
2, mirror silver NO.2, can print PET, PC, PVC, PMMA.
3, mirror silver NO.2BS is reduced by 30% solvent NO.2
4, color mirror ink NO.3, there are gold, red gold, green gold, is a high viscosity of the mirror ink, can print PET, PC, PVC, PMMA.
Third, the printing skills of mirror ink:
1. First of all, it should be understood that the mirror ink is as thin as water. The printing technique is the key. When the printing speed is slow, on the one hand, the water-like mirror ink will leak under the screen. On the other hand, the mirror ink can easily absorb the moisture in the air. The mirror effect obtained is not good. For this reason, in the printing, the mirror ink must be continuously and quickly printed after being poured on the screen, so that the printing can be smoothly performed. Even if the workpiece is inspected while printing, the speed will affect the printing effect, for example, blocking. Net, ink can not be printed, slag group on the screen.
2. The ambient temperature and humidity when printing mirror ink is very important. Because the ink is easy to dry on the screen, it can not be screen printed in an environment with large air circulation, otherwise it is very easy to block the net and become agar-like, and when the air humidity is high, the mirror effect is poor, therefore, When screen printing, as far as possible to avoid air flow and humidity, the screen printing environment should be enhanced dehumidification treatment. If the mirror ink is stored at 20 ° C and screen printed at 20 ° C, the printability will be better.
3, because the ink is as thin as water, so you should choose high mesh screen, not only that, the hardness of the squeegee should be harder, can be more than 80 °.
4. The mirror ink must be fully stirred before use, so that the metal powder and the resin should be fully mixed evenly to ensure the appearance of the mirror effect. Otherwise, the mirror effect will be affected.
5, the tension of the screen is slightly lower, the mesh distance is also adjusted closer, and the scraping pressure of the scraper is appropriately reduced, so that the mirror effect can be produced.
6. When mechanical printing, the ink returning knife used can not use hard aluminum or stainless steel, but should use the glue back ink knife to ensure uniform coating of the screen printing ink, so that the mirror effect is consistent.
7. The mirror effect of the mirror ink is related to the drying method. In terms of the mirror effect, the natural drying is not as good as heating and drying. Note that the heating temperature and the drying time should be the same, otherwise the mirror performance and color saturation will also be There is a difference.
Fourth, the screen printing process parameters recommended by the mirror ink, on the Japanese Seiko several mirror ink, the printing parameters are:
1. The screen version uses 270~300 mesh/IN screen.
2, the photosensitive coating is selected to be solvent-resistant, such as Sanhe Kemeilai's CP2 photosensitive adhesive or British Ketutai's PLUSII photosensitive adhesive or thin capillary film.
3, the squeegee (scraper) is 80~85°.
4. Thinner: It is not required under normal conditions. If necessary, T-1000 thinner can be added. Stir well before use.
5, silk screen environment: low temperature, low humidity, continuous silk screen, printing environment does not require air circulation.
6. Drying: 10~15 minutes at 80°C, 15~20 minutes at 60°C, 20~30 minutes at room temperature.
Five, the use of mirror ink notes:
1. If you need to cover other series of inks on the mirror ink, you should choose a series of inks that are not eroded by the mirror ink. Otherwise, the effect of the mirror will be destroyed.
2, the printing mirror ink must be thin and uniform, at the same time, the mirror ink itself can not overlap printing, overlapping printing will occur between the metal powder in the mirror ink. If the mirror ink is used on the IMD, the mirror ink should be >0.5mm away from the cut edge to prevent damage to the edge of the mirror ink when trimming the PC.
3. For PC and PMMA transparent formable sheets, internal stress often exists. When printing, pay attention to the erosion of these materials by solvent, not only lose the mirror effect, but also cause the stress of the material to be released under the action of solvent. Cracking, therefore, before silk screen printing, must be tested before production or such sheets must be aged and anti-cracking treatment.
4. After printing the mirror ink on inorganic glass, it can't be dried by natural or low-temperature drying method. It must be dried above 100 °C, so that the mirror ink can have good adhesion on the glass and also has a good mirror effect.
5, mirror ink is rare as water, usually, no thinner. It is worth noting that when the viscosity becomes high, it can be diluted with a special thinner and printed after the viscosity is restored, but if the mirror oil is agglomerated, the thinner cannot be used.
6, mirror ink should be stored in a sealed container, the ambient temperature <25 ° C, otherwise it will be degraded, or long storage time will naturally deteriorate, once the viscosity becomes higher, the ink becomes hard, discolored, indicating that it can not be used.