Analysis of UV Adhesion of UV Ink Varnish

The packaging and printing industry has developed rapidly in the direction of rapid, multi-color, and one-time printing. UV inks and UV varnish have become the new darling of packaging and printing materials. However, with the application of time, applications continue to increase, people have put forward newer and higher requirements for these products: not only need to quit on the printing machine, but also can be quickly dried after printing; not only the low cost of materials , but also high gloss; not only have to store a long period of time, but also printing, roll coating and good adhesion.

At present, there are few that can meet the above requirements at the same time. The packaging printer operator is concerned with the adhesion of the printing ink film and the roller coating film, and secondly, it can flow without freezing at low temperatures.

Whether it is UV ink, or UV Varnish, packaging and printing plant is afraid of the high temperature and humidity in the season; second is that the moisture content of the substrate exceeded. Because the printing or glazing on the above-mentioned workshop environment and substrate is extremely easy to be pulled off when the initial bolt (tape paper) is pulled off, the film is returned by the user. For example, the author found in the “Shuanghui” Group in Luohe, Henan Province: The group’s ham sausage carton packaging was sealed with adhesive tape. When the consumer peeled the tape, the decoration (ink and varnish) on the packaging seal was pulled off. It reduces the quality of the packaging product (face) view and directly damages the company's brand image. Another example is the Nanjing Gold Foil Group's printing of cigarettes on Wuhan Golden Dragon Cigarettes. When they are automatically labelled at high speeds of 140°C-160°C, they are often difficult to label in a continuous labeling process, that is, they are not resistant to high temperatures or cut off. Falling printed graphic blocks.... This not only affected the reputation of the gold foil group with certain popularity, but also increased the scrap rate for the users.

From the photocuring resin or prepolymer to the amount of cross-linking agent, from the different brands, technical parameters and actual proportions of photosensitizers to polymerization inhibitors, it is considered that: some existing manufacturers ignore the role of cross-linking agents, an ideal The cross-linking agent is also an ideal reactive diluent, not only miscible with the tree wax, but also capable of dissolving and diluting the unsaturated polyester, the resin, lowering the viscosity of the ink and the varnish system, and improving the fluidity of the ink and varnish. And can participate in the photo-curing reaction, so often in its formulation is too small, so that the ink flow is not good and the agglomeration of varnish, not frost; Second, the excessive use of photosensitizer can not only improve the speed of light curing, but also production The corresponding increase in the cost, excess photosensitizer, will reduce the UV open car or UV coating conjunctival strength and so on. In the field, new material preparation and production process adjustments, trials, comparisons of application methods, light intensity and light energy recording in the photochemical reaction process, curing speed, and workshop environment temperature and humidity control, substrate material PU value and moisture content (1 %, 2%, 3%, 5%, 6%, 7%, 8%) Comparison found that: whether it is alcoholic sol or polyvinyl chloride primer to the substrate of the substrate, the water content is controlled at 3%, so Said printing UV ink and roller coating UV coating oil due to poor fluidity, agglomeration adhesion is not good, all related to the water content. To improve the adhesion strength of the ink film, first, replace the new UV ink and UV varnish. Second, add 3%-6% of the JS-PPH (302) film forming aid from Shanghai Jinshan Chemical Plant to the ink or varnish. Agents, or adding 0.2% -0.5% of JS-F4011 adhesion promoter or adding 5% -15% of CH3COOC2H5, can ensure that the adhesive strength of package printing ink ink film and coating oil film has been fundamentally improved.