Prepress and printing processes for shrink film labels

Prepress processing

As a heat-shrinkable film label, shrinkage deformation is inevitable during the printing process, sometimes even more serious, and the shrinkage may be different in different directions and positions. Therefore, how to design the graphic and barcode distortion before the printing is to make the shrink label different from other prints. Below is a brief analysis of how to deal with it.

1, pre-press treatment of heat shrinkable film

Theoretically speaking, to obtain good printability on plastic films, the surface tension of the film should be higher than the surface tension of the ink, and the surface should have a certain roughness to form the adsorption force.

In the plastic film, polyolefins such as PP and PE films are non-polar high-molecular materials and have stable chemical properties and small surface tension, which is lower than the tension of the ink. The ink adhesion ability is poor. Although some films have surface tensions that are comparable or even higher than the ink tension, they have a smooth surface and a small pore-free surface with low adsorption force. At the same time, various film anti-aging agents and other anti-aging agents added to synthetic resins also affect the film surface tension. The surface properties of the film degrade its printability. Therefore, there are some printability problems in most shrink films. Therefore, in order to improve the printability of the film surface, the surface of the film with poor printing performance must be pretreated to increase the surface tension and the surface adsorption force. Common methods include corona treatment, plasma treatment, chemical treatment, coating treatment and so on.

2, the determination of the size of the label image

First, according to the thickness of the shrink film, the horizontal and vertical shrinkage of the film and the allowable shrinkage in all directions after the package, the deformation error allowed after the text shrinkage deformation, etc., to determine the size of the text on the shrink label to ensure the shrinkage deformation After the picture can be accurately restored.

3, the design of heat shrink labels

The graphic design of the shrink label needs to consider the appearance of the container. Designers in the pre-press department need to correct the deformation of certain parts of the label, and do not put the key image on the place with high shrinkage as much as possible. In addition, it is also possible to work with container manufacturers to make the density of the containers suitable. Whether it is in the smaller size or in the larger size, it can provide the correct shrinkage.

printing art

At present, the printing of heat-shrinkable film labels mainly uses gravure printing, using solvent-based inks, because of the high accuracy of gravure printing plates, the printing quality of gravure printing on the film is the best in all printing, and the thickness of the ink layer is strong. Rich levels. Moreover, the printing plate has a large printing rate, which is suitable for long-lived printing, and the printing amount of labels is often relatively large, so gravure printing is more appropriate. However, gravure plate making is complicated, has a long cycle, high cost, and is easily polluted. Followed by flexographic printing, with the development of flexo plate making and printing technology, clear and clear printing, gravure with a thick and high gloss, as well as flexo more use of water-based ink, is conducive to environmental protection, so the environmental protection requirements to improve flexibility Printing will have a greater application. In addition, offset printing and digital printing also have a range of applications to meet the specific needs of customers.

Although the development of heat-shrinkable labels in China is not as popular as other labels, heat-shrink labels are not as favored as self-adhesive labels because of their high occupancy, because they do not have many obstacles that are difficult to overcome. Attracting the curiosity of the printing industry; in addition, the overall level of heat shrink labels is relatively low, and the limitations in market expansion and process development are also reasons for its bad performance. However, with regard to the current status of the application of heat-shrinkable labels, the use of such labels will be more and more, but the form will not change, only the material will be improved, more in line with environmental protection requirements, the future trend will be to the environment The direction of development.