UV ink, UV coating oil adhesion strength
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The packaging and printing industry is developing rapidly in the direction of fast, multi-color and one-time printing. UV ink and UV varnish have become the new favorite of packaging and printing materials. However, with the application time and the increasing application field, people have put forward new and higher requirements for the above products: not only do not dry on the printing machine, but also can be quickly dried after printing; It has to be high in gloss; it has to be stored for a long period of time, and it must be printed and coated with good adhesion.
At present, almost none of the above requirements can be achieved at the same time. The packaging and printing operator is concerned with the adhesion fastness of the printing ink film and the roll coating film, and secondly, it can flow without being agglomerated at a low temperature.
Whether it is UV ink or UV varnish, packaging and printing factory is afraid of working in the season with high temperature and humidity; second, it is afraid that the moisture content of the substrate will exceed the standard. Because it is easy to be pulled off by the initial plugging (tape paper) after being printed or glazed on the above-mentioned workshop environment and substrate, it is returned by the user. For example, the author found in the “Shuanghui” group of Luohe, Henan: the ham sausage carton packaging of the group was sealed with tape paper. When the tape was peeled off during consumption, the decoration (ink and glazing oil) on the packaging seal was pulled off in blocks. It reduces the quality of the packaged goods (face) and directly damages the brand image of the company. For example, Nanjing Gold Foil Group prints the mouth flowers on Wuhan Jinlong cigarettes. When it is automatically labeled at 140°C~160°C, it is often difficult to label in the continuous labeling process, or it is not resistant to high temperature or cutting. Falling print graphic blocks... This not only affects the reputation of the gold foil group with a certain reputation, but also increases the scrap rate for users.
The above inks and varnishes are peeled off due to the difference in adhesion between them and the substrate. How to improve the adhesion strength.
After many investigations and combined with the experience of previous years, I visited the predecessors of the printing industry. From the photo-solid resin or prepolymer to the amount of cross-linking agent, from the photosensitizer to the different brands of the polymerization inhibitor, technical parameters and actual proportion analysis, it is considered that some existing manufacturers ignore the role of cross-linking agent, an ideal The cross-linking agent is also an ideal reactive diluent, which is not only miscible with the tree wax, but also dissolves and dilutes the unsaturated polyester, the resin reduces the viscosity of the ink and the varnish system, and improves the fluidity of the ink and the varnish. And can participate in the photo-curing reaction, so it tends to be less in the formulation, which indicates that the ink fluidity is not good and the varnish is agglomerated, not anti-freezing; the second is that the amount of photosensitizer is too large, mistakenly believe that the photosensitizer can The main light curing speed, in fact, is not the same, the amount of use, not only can not improve the speed of light curing, but also the corresponding increase in production costs, excessive photosensitizer, will reduce the film strength of UV gondola or UV coating oil and so on. At the scene, the preparation of new materials and production process adjustment, trial use, application method comparison, light intensity and light energy recording of photochemical reaction process, curing speed and workshop environment temperature and humidity control, substrate PU value and moisture content (1 %, 2%, 3%, 5%, 6%, 7%, 8%) After comparison, it was found that whether the alcohol sol or the polyvinyl chloride primer is used as the substrate of the substrate, the water content is controlled at 3%, so It is said that the printing UV ink and the roller coating UV coating oil are not related to the water content due to poor fluidity and poor adhesion of agglomerates. Improve the adhesion of the ink film. First, replace the new UV ink and UV coating oil. Second, add 3% to 6% of the JS-PPH (302) film forming aid from Shanghai Jinshan Chemical Plant. Adding 0.2%~0.5% JS-F4011 adhesion promoter or adding 5%~15% CH3COOC2H5 can ensure the adhesion strength of the ink film and glazing film of the package printing is fundamentally improved.