UV ink, UV coating adhesion strength

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 bolting (tape paper) pulls off the ink film or film, it 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 printing ink on the Wuhan Golden Dragon Cigarettes. When it is automatically labelled at high speeds from 140°C to 160°C, it is often difficult to label the labels in the continuous labeling process, that is, it is not resistant to high temperatures or cuts. Falling print 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. The above mentioned inks and coating oils were peeled off due to the difference in adhesion strength between them and the substrate. How to improve adhesion strength. The author investigated Hunan Yiyang, Pudong, Shanghai, Zhangjiagang, Jiangsu, Wuxi, Xinxiang, Henan, Xiangyang, and Qingdao, Shandong Province. Combined with previous years' experience, the author visited seniors in the printing industry. From the photo-curing resin or prepolymer to the amount of cross-linking agent, from the different brands, technical parameters and actual ratios of photosensitizers to polymerization inhibitors, it is considered that: some existing manufacturers neglect 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 in their formulations are often less, so that the ink flow is not good and the agglomeration of varnish, does not freeze resistance; the second is the excessive use of photosensitizer, mistakenly believe that: photosensitizer can mention The main photocuring speed is actually not enough, and the amount is more, not only can not increase the speed of photocuring, and the production cost is correspondingly increased, and the photosensitizer is excessive, which will reduce the conjunctival strength of the UV open car or UV varnish. 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 The comparison of %, 2%, 3%, 5%, 6%, 7%, 8%) found that whether the alcohol or sol-gel primer is used for printing substrates, the moisture content should be controlled at 3%, so Said printing UV ink and roller coating UV coating oil due to poor mobility, agglomeration adhesion is not good, are related to the water content. Improve the adhesion of the ink film First, replace the new UV ink and UV coating, and add 3% to 6% of the JS-PPH (302) film-forming aid from Shanghai Jinshan Chemical Plant to the ink or coating oil. Agents, or adding 0.2% to 0.5% of JS-F4011 adhesion promoter or adding 5% to 15% of CH3COOC2H5, can ensure that the packaging printing ink ink film and coating oil adhesive strength has been fundamentally improved.