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Flexible packaging gravure quality requirements
Gravure printing is the main printing method for plastic film printing today. The quality of gravure plastic film products is high. The quality standards of printing appearance are as follows:
(1) After the flowering process, the registration error of each color pattern is not more than 0.3 mm.
(2) Check the specifications of the film, and the registration error of each color pattern is not more than 0.3 mm.
(3) Check the ink color of the printed product, and require the hue to be correct, bright, uniform, bright in ink, soft in ink, and smooth in the edges of the print.
(4) Printing fastness, requiring transparent tape to stick ink without discoloration.
(5) Pattern text lines, requiring clear and complete, no defects, no deformation.
(6) The netting requirements are rich in layers and the outlets are clear.
(7) The product is neat and tidy, with no obvious dirt or knives.
(8) It is required that the deviation of the same color density of the product and the same batch of the same color and color difference meet the requirements of GB7707-87.
Process control points
In order to better meet the above quality requirements, we can control the gravure film process from the following main aspects:
1. Master the technical points of various plastic packaging film substrates
1BOPP is the most commonly used printing substrate. The production process is a typical plastic gravure production process; it is printed with polyamide or chlorinated polypropylene ink, with appropriate tension and embossing force, and the drying temperature is controlled below 80 °C .
2BOPET printing points: Because PET is usually thin, easy to wrinkle, requires a large tension during printing, has a certain selectivity to the ink, easy to leave the layer with general printing ink, the film is static, easy to block up (not online ), raising hair and scraping marks (knife wire) phenomenon, the humidity of the workshop is great when printing .
3BOPA printing points: BOPA is a film that is easy to absorb moisture. Therefore, the printing environment must ensure that the ambient humidity of the printing machine should not be too high (if there is no dehumidification, the environment with high humidity is not suitable for printing nylon film); the unprinted film can not destroy the original aluminum film packaging film, and should be printed immediately after opening. The nylon film needs to be preheated during printing (if the machine does not have a preheating device, the printing plate can be installed in the second color, and the first color is used for preheating), and the preheating temperature is 50 to 80 ° C; The printing tension should be appropriately reduced; the pressure should be moderate; the ink adaptability is strong, depending on the product structure selection, if it is the cooking bag, the cooking ink must be selected ; after printing, the product must be sealed and placed in the dry and ripening room, as soon as possible. complex.
4K coating film (KOP, KPA, KPET) printing points: Because the K coating film is either roll-coated or spray-coated, its thickness uniformity is not very good, the surface is not flat, and PVDC is just brittle, during printing The printing tension and the embossing pressure should not be too large , the overprinting is difficult, and the ink transferability is poor. When printing the shallow screen, it is easy to take a flower (some of the dots are lost), and it is necessary to use a higher hardness pressure roller for printing.
In addition, it is selective for the solvent. If the solvent is used improperly, the coating may be dissolved, the solvent of the printing film is large, and it is easy to stick, so special attention should be paid to drying and cooling. The printing of the matte film can be printed on the smooth surface by the OPP process, but the matte layer on the surface cannot withstand high temperatures, and the drying temperature needs to be controlled.
5 pearlescent film is printed with surface-printing ink, and as far as possible, a transparent ink with good transparency is used. Heat shrink film printing should use a very low drying temperature, choose a special heat shrinkable ink (printed ink layer should be able to shrink by heat without falling), if it is a PVC heat shrinkable film, consider the solvent to dissolve the film. Sex.
6 unstretched PP, PE film printing tension is small, overprinting is difficult, the design of the pattern should fully consider the amount of deformation of the printing.
2. Preparation of prepress technology
1 plate design: At the time of plate making, the original designed by the design company needs to be modified according to the characteristics of gravure printing, making it more suitable for printing needs. For the need of overprinting, such as small lines, text can not be multi-color overprinting, the color of the pattern can not have small anti-white characters, should not be left blank in the color pattern, put on other small text, require overprinting for portraits, etc. Strict version, black, blue, red, yellow version in the middle as far as possible without other color version. For printing needs, the barcode should be arranged as much as possible in the direction of the line in the circumferential direction of the magazine. In terms of color guarantee, if there are conditions, it is best to separate the large ground color and the layer pattern version, and use the special version as much as possible. The hanging version must fully consider the two color jump zones of 80% and 5%. When the network is tapped, the limit of the dot should be above 10% .
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