Now there are more and more packaging printing companies, so packaging printing must not only do well, but also do better than others. HereChinaprinting4Uwill introduce what are the precautions in the packaging printing process.
1. The thickness and area of the ink
The thickness of the ink printed on the substrate directly affects the quality of the printed product. The graphics and text areas on some packaging prints are too large, which makes it unlikely that the ink layer will adhere to the plastic film, resulting in delamination and blistering. The main reason is that the ink layer changes the porous surface properties of the paper, closes the pores of the paper fibers, and prevents the penetration and swelling of the adhesive on the paper. Therefore, the amount of ink printed must be strictly controlled during the packaging and printing process, usually in the range of 2-3μm.
2. Inks for packaging and printing
Packaging and printing coating products should use fast offset printing and bright offset printing inks. The adhesive is composed of synthetic resin, dried vegetable oil, high boiling point illuminating oil, etc., because it is a fast-curing bright offset printing ink. The molecular groups and mutually bonded groups of these synthetic resins swell and penetrate each other, which leads to cross-linking and the formation of physical and chemical cohesion. This is beneficial for coatings.
3. The surface and inner layer of the printed matter are dry, and the ink layer on the surface or inner layer of the printed matter is not dried, which will seriously affect the quality of the film and cause quality problems such as blistering and delamination. There are many factors that affect the drying of the ink layer on the surface of packaging prints, such as the type of ink, the amount of desiccant, the structure of the paper, the temperature and humidity of the working environment.
Therefore, special attention should be paid to the drying of the ink layer when printing. Printing strictly controls the balance of ink and water, pays attention to the emulsification of ink, and controls the acid value of the dampening water. At the same time, control the temperature and humidity of the workshop. Let the surface and the inside of the packaging printed matter be completely dry to ensure the quality of the film.
4.The addition and release of printing powder
In order to adapt to the high-speed printing of the multi-color machine and keep the back of the paper clean, powder spray is usually used to solve the offset printing problem on the packaging. Most of the powder applied consists of cereal starch and natural suspended matter. These powder particles are coarse. If too much powder is sprayed during the printing process, these powder particles will float on the surface of the print. When laminating, the adhesive will not adhere to the ink layer anywhere, which will seriously affect the quality of the laminated film. Therefore, the offset printing of packaging requires strict control of the amount of powder dispensed. The amount of clean powder spray is very small.
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