Gravure printing is a direct printing method, so it requires more materials. This paper lists the printing adaptability of common printing materials and the corresponding production methods of different printing substrates.
Printability of common substrate materials
The printing of plastic film requires the substrate film to meet the following five requirements: 1) the surface is smooth and smooth, without obvious stiffness, yellow black spots, holes, and excessive wrinkles. ② The average thickness error of substrate film to be printed should be within 10% (when printing width is 1m). ③ Under the printing tension, the elongation of the substrate film to be printed should be within 1%. ④ The surface tension of the substrate film to be printed is more than 40 dyn / cm. ⑤ The affinity between the substrate film and the printing ink should be known in advance. For the film which is easy to dissolve and swell in the ink, the printing speed and ink concentration may be higher. When coating substrate film coating layer printing, we should understand the adhesion between coating resin and ink.
Different printing substrates have the same printing adaptability. In order to achieve better results, different processes should be selected for production. ① BOPP is the most commonly used substrate, and its production process is a typical plastic gravure printing process: using polyamide or chlorinated polypropylene ink for printing, appropriate tension and impression force. The drying temperature should be controlled below 80%.
② Key points of BOPET printing: because pet is usually thin and easy to wrinkle, large tension is required during printing, so it has certain selectivity for ink. When using general printing ink, it is easy to separate layers, block up (not on the Internet), fuzzing and scraping (knife marks) are easy to occur. High humidity in the workshop is good for printing.
③ Key points of BOPA printing: BOPA is a film easy to absorb moisture and deform. Therefore, it is necessary to ensure that the environmental humidity of the printing machine should not be too high (if there is no dehumidification measures and the environment with high humidity is not suitable for nylon film); the unprinted film can not damage its original aluminum film packaging film, and it should be printed immediately after opening, and the nylon film should be preheated during printing (if there is no preheating device on the machine, the printing plate can be installed after the second color, leaving the first color for printing For preheating), the preheating temperature should be 50-80 ℃; the printing tension should be appropriately reduced; the pressure should be moderate; the ink adaptability should be strong, depending on the product structure. If it is a cooking bag, cooking ink must be selected. After printing, the product must be sealed and packaged and compounded as soon as possible.
④ K coating (Kop, kPa, kpet) printing points: because the thickness uniformity of K coating film is not very good, the surface is not smooth, and the PVDC is rigid and brittle, so the printing tension and embossing pressure can not be too large during printing, the overprint is difficult, the ink transfer is poor, and the printing dot is easy to appear when printing the shallow screen (part of the dot is lost), so it is necessary to use high hardness pressing Roll for printing. In addition, it is selective to solvent. If the solvent is not used properly, the coating may be dissolved. The residual solvent of printing film is large and easy to adhere. Therefore, special attention should be paid to drying and cooling.
⑤ The OPA process can be used in the printing of Matt Film on its smooth surface, but because the surface of the matting layer can not withstand high temperature, it is necessary to control the drying temperature.
⑥ Pearlescent film using surface printing ink for surface printing, and try to choose a good transparency of the surface printing ink.
⑦ Heat shrinkable film printing uses a very low drying temperature, to choose a special heat shrinkable ink (silver ink layer should be able to heat shrink without falling), if it is PVC heat shrinkable film, also consider the solvent solubility of the film. ⑧ The tension of UN stretched PP and PE film should be very small, so it is difficult to overprint. The deformation of printing should be fully considered in the design of pattern.
Different printing base materials should be considered from the aspects of ink selection, plate making design and printing process. For different printing substrates, adjustments must be made from the selection of ink, plate making design and printing process, so as to ensure the quality of products to meet the requirements. In addition, some high barrier coating materials should not be printed on the coating surface as far as possible in case of damaging the barrier coating.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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