Common problems and countermeasures of UV frosted ink in printing
Time:2022-07-01
Views:3324
Because of its printing products have a strong sense of sand, beautiful, elegant, generous, so the promotion is very fast, just a few years, in cigarette bags, wine bags, cosmetics and other high-grade packaging printing field occupied a considerable proportion. However, in the printing process, especially in the large-scale industrial production, there are inevitably some problems. Here, we will talk about the problems and countermeasures in the process of UV frosted ink printing.
1. The sand feeling is not good, and the performance is not strong.
Main reasons:
(1) Improper selection of fillers in frosted ink, particle size is too small;
(2) Improper filling amount;
(3) Improper selection of scraper;
(4) Improper selection of mesh size.
Solutions:
(1) According to the requirements of the sand sense of the printed matter, the appropriate diameter of the filler can be selected;
(2) Increase the amount of filler appropriately;
(3) Choose the appropriate hardness of the scraper.
Generally speaking, the higher the hardness of the scraper, the more distinct the printed pattern, the lower the hardness of the scraper, the easier the printed pattern is, resulting in a weakened sand feeling. At the same time, adjust the mesh plate can obviously improve the sand impression. Generally speaking, for the same type of frosted ink, the lower the mesh, the more intense the sand.
2. Mirror contrast effect is not obvious.
Main reasons:
(1) Substrate own gloss is not high;
(2) The amount of fillers in the frosted ink is too large to completely cover the substrate;
(3) The matte degree of filler is not high, resulting in a mirror substrate and ink film surface contrast is not strong.
Solution: In the selection of appropriate filler at the same time, as far as possible to choose high gloss mirror substrate.
3. The surface of the printed matter is gray and inked.
Main reasons:
(1) Improper selection of mesh;
(2) The surface of the substrate is greasy;
(3) Frosted ink contains low volatile oil impurities.
Solutions:In general, for the packing and the diameter of particles, if choose high mesh screen, because the mesh is small, not easy to get through when printing ink or by very few, make the inked unevenness, appear gray phenomenon, and the existence of oil make inking difficult or spots, white phenomenon, this kind of situation can be by selecting the appropriate screen clean and the corresponding measures to deal with.
4. Paste occurs during printing.
Main reasons:
(1) The viscosity of matte ink itself is too large;
(2) The network distance is too small;
(3) The number of mesh mesh is too low;
(4) The printing pressure is not appropriate.
Solution: minimize the viscosity of matte ink resin, adjust the distance between screen and substrate, choose the appropriate mesh screen or adjust the printing pressure.
5. Penetration occurs when printed matter is stacked.
Main reasons:
(1) The curing speed of the matte ink material itself is not enough;
(2) The substrate has moisture or other solvents;
(3) Curing time is too short.
Solution: choose the fast curing speed of light solid resin, can also appropriately increase the amount of photoinitiator or photosensitizer, appropriate extension of curing time, keep the substrate dry and clean.
6. The print has turtle grain.
Main reasons:
(1)The curing time is too long;
(2) The resin in the frosted ink is poor in toughness;
(3) Improper way of stretching net.
Solution: Due to too long curing time will cause excessive curing and post-curing, resulting in cracking. Therefore, it is necessary to control the curing time and choose the flexible photosetting resin and active monomer to improve the turtle grain phenomenon. The use of diagonal net to replace the way of stretching net, also can avoid the generation of turtle lines.
7. The adhesion of printed matter is not good.
Main reasons:
(1) Due to the uv curing resin and active monomer will inevitably occur volume shrinkage, is bound to affect the adhesion of frosted ink on low surface energy, non-polar substrate;
(2) The surface of the substrate has silicone oil, powder spraying, dust and other impurities.
Solution: For low surface energy, non-polar substrates such as PE, PP, PET, etc., corona treatment or other chemical and physical treatment should be carried out in advance, before debugging and use, while keeping the printing substrate clean.
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