Compared with traditional labels, self-adhesive labels do not need glue, no paste, no water, no pollution, save labeling time, and are convenient and quick to use in various situations. Different types of labels for different fabrics, adhesives, and backing papers can be applied to materials that are not suitable for general paper labels. It can be said that stickers are a universal label. The printing of self-adhesive labels is very different from traditional printing. Self-adhesive labels are usually printed on the label coupler and multi-processes are completed at one time, such as graphic printing, die-cutting, waste disposal, cutting, or reworking. Volume and so on. That is, one end of the raw material for the entire volume is input, and the other end is the finished product. Finished products are divided into single sheets or rolled labels, and the finished labels can be directly applied to the goods. Therefore, the label printing process is more complex and the requirements for equipment performance and printing staff quality are also higher.
Compared with ordinary paper, film material has many advantages. Film material printing is the direction of future adhesive printing. We briefly describe the structural characteristics of the film material, printability and post-printing process:
1, the structure and characteristics of film materials
(1) Structure
The film material has the same structure as the paper material, with the only difference being that the material surface needs to be treated.
(2) Surface characteristics and treatment methods
The principle of the ink layer forming a pattern on the print is penetration, volatilization, conjunctiva, and curing. Due to the high density of the film, the ink only evaporates and conjunctiva. There is no penetration during the curing process and the film surface needs special treatment. The role of surface treatment is to increase the surface tension of the film, making it greater than the surface tension of the ink, so as to achieve the correct combination of ink and film materials. Surface treatment usually has the following methods:
Corona treatment: The high-voltage charge is discharged to the surface of the film, and the purpose of increasing the surface energy, that is, the surface tension is finally achieved. Corona treatment is generally carried out at a thin film manufacturing plant. Since the surface tension is time-limited, it requires strict inspection before printing. Therefore, some advanced equipment has a pre-press corona treatment device to print high-quality film products.
Printing process: Chemically altering the surface characteristics of the film to make it suitable for ink printing or ribbon printing.
Surface coating: The use of chemical coating on the surface of the film increases the surface tension and changes the surface properties.
2, the printing process of film materials
(1) Printing Process of Thin Film Materials
The basic printing methods include gravure printing: gravure ink printing and gravure water ink printing; offset printing: UV offset ink printing; embossing: common resin ink printing and UV embossing ink printing; flexo printing: water-based printing Ink printing, solvent ink printing and UV ink printing; silk screen: divided into UV ink printing and solvent ink printing; combination printing: divided into embossing + screen printing, embossing + flexo, flexo + screen printing, offset + embossing four Printing method. Here are some more specific printing methods used:
A, ordinary resin ink printing. This is the most common method currently used. Due to the problem of drying, there are two kinds of drying methods: cutting leaflets and drying on shelves. This method has a long drying time, covers a large area and is easy to pick up. Laminated film. The undried ink is wrapped in the film. Care must be taken to avoid overcoating the film and preventing film failure.
B, UV ink stamping. This method has good printing quality and high efficiency. It is a kind of printing process that has the most development in China and is most suited to the national conditions. Since the domestic embossing equipment generally does not have UV devices, the printing of the film is limited, so the equipment is renewed and transformed is a necessary condition for the printing film.
Source: China Printing Packaging Network