Master These Points to Easily Solve Common "Difficult Problems" of UV Ink

There are many problems in the use of UV ink, such as incomplete curing, poor adhesion and ink piling, which trouble label printing enterprises. This article will briefly discuss these problems with everyone.

01 Incomplete Curing: Phenomena and Solutions

If UV ink is not fully cured, the ink layer's adhesion is poor. During printing, the ink layer may stick to the back of adjacent prints, causing dirty prints. Also, the ink layer's surface is not abrasion-resistant and can be easily scratched during subsequent processing and use, which seriously affects print quality.

The most effective solution is to switch to faster-curing UV ink. Alternatively, use higher-color-concentration ink to achieve expected colors with a thinner layer, improving curing efficiency. In some cases, adding a small amount of slip or curing additive can enhance curing efficiency. However, adding additives is generally not recommended to avoid chemical reactions.

02 Poor Adhesion: Phenomena and Solutions

Poor adhesion of printed ink layers is not always caused by the ink itself but is also closely related to the surface properties of the substrate. If changing or adjusting the ink does not solve the problem and the substrate cannot be changed, there are two solutions.

Solution 1: Before printing colored ink, print a layer of transparent, high-adhesion medium to improve the substrate's surface properties. This medium is printed in the first unit of the press and UV-cured.

Solution 2: Before printing, coat the substrate with water-based clear coat to solve adhesion issues like ink bursing. The water-based clear coat is applied by roller coating and infrared-dried. This solution is for substrates like gold/silver card stock and laser card stock, where UV ink adhesion is unstable.

03 Ink Piling: Analysis and Solutions

Ink piling refers to ink accumulating on the blanket, plate, and rollers, causing poor ink transfer and resulting in blurry printed images. The main causes include poor ink flow, transfer, paper powder mixing into the ink, insufficient ink fineness and, in offset printing, ink emulsification by dampening solution.

To solve ink piling, use tackreducers or plasticizers to adjust ink tack and viscosity. For offset printing, switch to water-resistant ink and avoid excessive water during printing.

Generally, the faster the UV ink curing speed, the higher the print surface hardness, the lower the flexibility, the worse the adhesion and the lower the gloss. Many ink suppliers have launched UV inks for different substrates. Label printers should comprehensively consider and weigh the options selecting when UV inks, and when encountering printing failures, they should apply targeted solutions.

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