Self-adhesive labels are the mainstream form of labels in the current market. How to make a high-quality self-adhesive label is a topic that many label companies are very concerned about.

The quality of die-cutting of self-adhesive labels is related to many factors, such as die-cutting method, die-cutting device accuracy, die-cutting plate accuracy, and the matching of die-cutting blades and materials. In addition, there are many types of self-adhesive materials with different properties. It can be said that different types of self-adhesive materials are the arrangement and combination of different types of surface materials, adhesives and backing papers. Due to the different properties of various face papers, adhesives and backing papers, their respective die-cutting characteristics are also different and have different effects on die-cutting quality.

What are the requirements for die-cutting quality of self-adhesive labels?

Below, the editor will mainly introduce the impact of the face material on the quality of die-cutting, and the countermeasures.

Type of face material

In the field of self-adhesive labels, the commonly used surface materials can basically be divided into two categories: paper and film.

The cutting principle of ordinary paper surface materials is slightly different from that of film surface materials. Although in theory, the face material and the adhesive must be cut through together during die-cutting, but in fact, the die-cut paper face material is a combination of the cutting of the tool and the self-breaking of the paper after the force is applied, that is, the cutting edge is cutting downward at the same time. The paper is also squeezed to both sides, and the paper breaks after being stressed. Therefore, the die-cutting accuracy of paper-based surface materials is relatively not very high. When we analyze the samples, we often see some labels with burrs and tears, which is caused by the natural fracture of the material itself due to the thick fibers.

Based on the die-cutting characteristics of paper-based surface materials and considering the wear of the blade, when using a flat die-cutting blade to die-cut paper-based surface materials, the angle of the blade is usually specified as 52°, because the higher the die-cutting angle during die-cutting The larger the material, the greater the extrusion deformation of the material, that is, the separation force in the horizontal direction will aggravate the fracture separation phenomenon of the material. It should be noted that some industry colleagues usually think that the die-cutting depth of paper surface material is two-thirds of the thickness of the paper. If you do this, it will bring other problems, such as difficulty in waste disposal, glue leakage, etc. Therefore, it is advocated that the surface material and adhesive should be 100% cut.

The die-cutting of film surface materials is simply a die-cutting process that is completely cut through. Because most of the film surface materials are tough and will not break naturally, the theory of cutting through two-thirds is not valid. It must be completely cut through the entire thickness, otherwise the waste edge will be peeled off together with the label.

Therefore, the edge of the die-cut film surface material should be sharp and the hardness should be high, and a small-angle die-cutting knife should be used. The blade angle is usually 30°~42°. If a die-cutting knife with a large angle is used, it is not only difficult to die-cut, but also when the blade is not sharp, the face material will not be cut through and the bottom paper will break first. In addition, it will also cause flanging on the edge of the finished label, resulting in glue leakage. In short, the precision of die-cut film surface materials must be higher than that of paper surface materials, so die-cut film surface materials have certain requirements for equipment accuracy, die-cutting plate accuracy and backing paper.

The strength of the face material

The strength of the face material is related to the thickness of the face material, the fiber (resin) structure and its own moisture content. In the die-cutting process of self-adhesive labels, the biggest influence on the strength of the surface material is the waste discharge situation, or the waste discharge speed, and the waste discharge speed is related to the production efficiency. Usually, label printing companies hope to have a high waste discharge speed. . In addition, the moisture content of the material directly affects its own strength, and the humidity is related to the production environment. Therefore, it is necessary to control the temperature and humidity of the production environment and storage environment of the surface material to prevent the material from being damp.

In addition, when designing the layout, in addition to considering the layout and text, it is also necessary to reasonably arrange the waste discharge size and waste discharge speed of the label according to the strength of the material through experiments, which can not only improve production efficiency, but also reduce material waste.

Thickness of face material

The thickness of the material directly affects the depth of die-cutting. The thicker the material, the easier it is to die-cut. Because the thicker the material, the greater the tolerance of the die cutting, the less chance of cutting through the liner. Conversely, the thinner the material, the easier it is to cut through the liner. We have done an experiment, in the same flat label die-cutting machine, die-cut two kinds of surface materials with the same backing paper, the basis weight is 80g/m2 and 60g/m2. During the process, we found that the material with a ration of 80g/m2 was die-cutting and discharged normally, while the material with a ration of 60g/m2 often experienced waste discharge and fracture, the bottom paper was cut through and the label was dropped. When many label printing companies encounter such situations in the production process, they can only use the adjustment method of frequent shutdown and repeated padding, which wastes time and materials, and even complains that there are problems with the materials. In fact, there are many reasons for this kind of situation. If the circular die-cutting method is adopted, or the die-cutting area is reduced, or high-precision equipment is used, this phenomenon can be avoided or reduced.

Therefore, when die-cutting thin surface materials, it must be carried out on high-precision equipment. At the same time, try to reduce the die-cutting area (especially small labels), and use die-cutting plates made by professional die-cutting plate manufacturers. version accuracy. The thickness of the surface material is proportional to the strength, which will directly affect the waste discharge rate. The waste discharge comparison test can be done with 80g/m2 and 60g/m2 materials respectively. The result is that the production efficiency of the former is 20%~30% higher than that of the latter. .