Low Voc Water Based Varnish

Due to the advantages of environmental protection and convenient use, Low VOC water-based varnish has gradually replaced solvent varnish and oily varnish. In the future, it is bound to be adopted by more and more printing manufacturers.

Low VOC water-based varnish is suitable for special on-line polishing unit, off-line roller coating polishing machine, flexo polishing, gravure polishing, etc., and the main applications before are on-line polishing (such as gaobao kba104, kba105) and off-line roller coating polishing. In particular, in addition to using less and no powder spraying, the wiring glazing can also greatly improve the printing efficiency (reduce the spacer) and reduce the waiting time for post-processing. The printed matter after connecting and polishing can be processed after die cutting and other post-processing after 2~6 hours.

However, no matter what method you choose, if you want to achieve satisfactory glazing effect. We must master the application method of Low VOC water-based varnish.

Therefore, in the process of using low VOC water-based light oil, we suggest to carefully grasp the following three factors:

1) Coating amount: after a uniform and appropriate amount of coating is formed, it has good gloss and high wear resistance. If the coating amount is small, the water-based varnish cannot form a complete and continuous film, resulting in poor gloss and failure to achieve the due protection and decoration effect. However, if the coating amount is large, the film will be thick, which will increase the polishing cost and affect the drying speed. In serious cases, the back will stick. We generally recommend that the wet coating film is 4 ~ 10g / ㎡, and the specific coating amount needs to be different according to the characteristics of paper and equipment.

2) Viscosity: the viscosity of off-line roll is generally recommended to be 18 ~ 25 seconds (din4, 25 ℃). The viscosity of connecting line polishing (such as Roland 705) is generally recommended to be 40 ~ 70 seconds (din4, 25 ℃)? Appropriate. The viscosity is too low to protect and decorate; If the viscosity is high, the phenomenon of poor leveling and slow drying may occur. Water based varnish and diluent are generally water, or the mixture of isopropanol: water 1:1 can be used as diluent according to specific conditions. The specific viscosity should be adjusted according to the characteristics of paper and equipment.

3) Drying temperature and time: water-based varnish mainly depends on osmotic drying and crosslinking curing. Common drying devices include hot air drying and infrared drying. General recognition? Infrared drying is the best. Cause? The main solvent of Waterborne Varnish is water, and the fluidization heat of water is relatively high, so the drying speed is slower than that of oily varnish. Similarly, the drying temperature is higher than that of oily varnish. Generally, it is recommended that the temperature is 80 ~ 100 ℃, and the drying channel is about 2m. If the temperature is not enough and the drying channel is too short, the film will not dry, and there will be sticking back and scratch in serious cases. However, if the temperature is too high, the drying time is too long, the water loss of paper fiber is too large, and the paper becomes brittle, which is easy to break and burst in post-processing.

Low VOC water-based varnish has good leveling and smooth film surface. In addition, the smoothness of the printing surface is greatly affected by the different types of paint, which can form a smooth film on the surface of printing products.

Low VOC water-based varnish has good leveling and smooth film surface. In addition, the smoothness of the printing surface is greatly affected by the different types of paint, which can form a smooth film on the surface of printing products.

Low VOC water-based light oil does not pollute the atmospheric environment: VOC (volatile organic gas) is recognized as one of the main sources of global air pollution; Solvent based varnish will emit a large amount of low concentration VOC, because the aqueous varnish uses water as the dissolution carrier. Therefore, whether in its production process or when it is used for printing.

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