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UV Wide Format Printer-What is the White Coating When Printing?

UV wide format printers are bringing a quiet revolution to the advertising, painting and other industries due to the diversity of their printable materials.

On many transparent materials, such as glass and acrylic sheets, a common printing technique is to add a white coating to the printed vivid color to set off the vivid colors of the picture. Usually this layer of white back coating is achieved by spraying a white UV ink on a dedicated nozzle on the printer. During our contact with the customer, it was found that after printing for a period of time, the white ink would crack and cause pattern damage.

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The reason for UV digital printer white ink cracking is mainly because the UV white ink is not high in strength and relatively brittle, and at the same time, the ink layer is stretched during the heating of the material due to the difference in thermal expansion coefficient between the ink layer and the substrate.

UV inkjet printer curing technology has been developed in the past 20 years, and its main advantages are fast curing and environmental protection. The shortcomings are also obvious. Due to the fast curing, the internal tension of the material is relatively large and the strength is not high. This problem is more pronounced in white ink. Generally, in order to achieve a certain hiding rate, white ink usually contains a relatively large amount of whitening filler such as titanium dioxide, and the presence of these fillers further reduces the toughness of the ink. Therefore, to avoid cracks caused by white ink, materials with higher toughness should be selected.

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In the general printing process, the UV large format printer does not need to be coated first, but it needs to be rubbed with a coating when it comes to metal printing materials. The coating of the UV printer needs to be wiped. The main purpose of the rubbing coating is to allow the coating to adhere better to the metal material and to clean the surface of the coating. Because the surface density of printed materials such as metal, glass, and ceramic tiles is too large, the ink cannot penetrate completely into the inside, so it is necessary to wipe a layer of coating.