What are the printing and processing methods of film materials?
The following are some printing processing methods summarized by professional printers in China for reference:
①Ordinary letterpress printing: It is the most commonly used printing method at present, suitable for printing from roll to sheet. Due to the use of oil-based relief inks, there is a drying problem. There are two drying methods:
a. After printing, cut a single sheet and put it on the shelf to dry. It occupies a large space and is easy to smear and adhere.
b. After printing, the film is laminated, and the ink that has not yet dried is compounded between the two films. Note that the label bleeding and die-cutting should be avoided after the film is covered, which may cause the film to fall off and cause quality problems.
②UV letterpress printing: It is an advanced printing method with good quality and high efficiency. Since the ink dries instantaneously, the film can be rewinded without coating. Suitable for roll-to-roll and roll-to-single printing. At present, the rotary printing and some intermittent paper feeding equipment are equipped with UV devices.
③Solvent ink flexographic printing. At present, inks made from harmful solvents such as benzene are basically not used, and solvent inks are all alcohol-soluble inks.
Due to the low surface tension of solvent ink, the surface tension of the film is not as strict as other inks, so the ink layer has strong firmness and good printability. Training materials are printed. Some film materials that are not suitable for printing generally use solvent inks.
④Water-based ink flexographic printing. Water-based ink has strict requirements on the surface tension of the film, and the ink that matches the film should be selected when printing. UV coating is required after printing to protect the ink layer.
In order to strengthen the firmness of the ink, the transparent alcohol ink can be printed on the surface of the film first, and then the water-based ink can be printed for better results.
⑤Flexographic printing with UV ink. The principle is the same as that of UV letterpress printing. It is the most suitable printing method for printing films, with good printing quality and bright ink. The dot distortion is small, suitable for color printing on the mesh. At present, UV flexographic printing is the fastest growing printing method in developed regions in Europe and America.
⑥Solvent ink screen printing. The traditional printing method generally uses single-sheet printing, and a very small amount is roll printing. Sheet-fed printing has low cost, good effect, and strong adaptability. It is currently the main printing method of sheet-fed film adhesive materials for Chinese printing companies.
⑦UV screen printing. It can be printed on a single sheet or on a roll, which is the latest printing method. Sheet-fed printing is currently widely used in UV screen imitation metal corrosion printing, using special UV screen inks to achieve special effects.
⑧UV offset printing. The latest international technology can print high-quality color graphics, suitable for long-version, high-level label production. Currently, UV offset printing applications are not common.
⑨Gravure printing. Including solvent-based ink and UV ink printing.
Gravure printing is the best quality printing method among all printing methods. With the appearance of label processing machines, more and more printers in China use gravure printing machines to print labels. The gravure printing machine is suitable for printing long-form, high-quality labels, such as beer labels, battery labels, etc.