Several common problems in the use of self-adhesive materials (1)
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With the continuous development of China's economy, self-adhesive labels have been widely used in various fields. However, due to the uneven economic development in China, the technical level of self-adhesive printing enterprises in many regions is relatively backward, and is often plagued by some problems. Therefore, in this article, I will share with you some of the problems that are easily encountered during the processing and use of stickers and give corresponding solutions.
Die cutting in the die cutting
It is a common phenomenon that the self-adhesive material has a waste edge breakage during die cutting. In the event of a break, the operator has to shut down to rearrange the waste, which in turn leads to reduced production efficiency and increased raw material loss. So what are the reasons for the breakage of the waste edge in the die-cutting of the self-adhesive material, and how to deal with it?
1. The material itself has low tensile strength and leads to the breakage of the waste side.
Some materials, such as glossy paper (also known as glossy coated paper), have shorter paper fibers and are relatively fragile. In the die-cutting process, the tensile strength of the waste side is lower than the discharge tension of the equipment, so It is easy to break.
If you encounter such a situation, you need to minimize the discharge tension of the equipment. If the discharge tension of the equipment has been adjusted to a minimum and it still cannot solve the problem, then it is necessary to design the waste side to be wider when designing the previous process, so as to ensure that the waste edge breakage does not occur frequently during the die cutting process.
2. The process design is unreasonable or the waste side is too thin to cause the waste edge to break.
At present, many labels for variable information printing on the market have easy-to-tear virtual knife lines. Some self-adhesive label processing enterprises are limited by the equipment, and have to place the dotted knife and the frame knife in the same die-cutting station. In addition to the cost and price factors, the waste side is designed to be very thin, usually only 1mm wide. This die-cutting process has extremely high requirements on the label material, and a slight inadvertent result in breakage of the waste side, thereby affecting production efficiency.
The author recommends that self-adhesive label processing enterprises, if conditions permit, try to die-cut the easy-to-tear virtual knife line and the label frame, so as not only can reduce the frequency of the waste edge breakage, but also greatly improve the die-cutting speed. . Enterprises without conditions can solve this problem in the following ways.
(1) Adjust the proportion of the dotted knife. Generally speaking, the denser the arrangement of the virtual cut lines, the more likely the problem of breakage of the waste side occurs. Therefore, we can adjust the proportion of the dotted knife, for example, to 2:1 (2mm cut every 1mm), the probability of the broken edge is greatly reduced.
(2) Remove the part of the virtual knife line beyond the border of the label. There are many die-cutting plates on which the dotted knives will be arranged longer than the label frame. If the waste edge is narrower, the dotted knives will cut off the waste edge that is already narrow, causing the waste edge to be easily broken. . In this case, you can use the plastic file to remove the dotted knife protruding from the outer border of the label, so that the strength of the waste side can be greatly improved, so that the waste side is not easily broken.
3. The breakage of raw materials leads to the breakage of waste
The cracking of the self-adhesive material is also likely to lead to the breakage of the waste side. This problem is relatively easy to find, and this article will not be repeated. It should be noted that some of the self-adhesive materials have smaller edges and are not easy to find. They need to be carefully observed to find out. In case of such problems, the defective materials are removed and then die-cut.
4. If the adhesive is too fluid or the amount of glue is too large, the waste edge will be broken.
The amount of the adhesive applied to the self-adhesive material has a great influence on the die-cut properties of the self-adhesive material. Generally, in die-cutting equipment, the self-adhesive material is not immediately discharged after die-cutting, but it is necessary to continue to transfer a certain distance forward, and it is only after the waste disposal station begins to discharge. If the adhesive is too thick, the adhesive will flow back during the transfer from the die cutting station to the waste disposal station, causing the already cut self-adhesive materials to stick together, resulting in waste. The edge breaks due to adhesion when it is pulled up. In general, the coating amount of the water-soluble acrylic adhesive should be between 18 and 22 g/m2, and the coating amount of the hot melt adhesive should be between 15 and 18 g/m2, exceeding this range. The self-adhesive material will greatly increase the probability of breaking the waste edge.
Some adhesives, even if they are not coated in a large amount, are easily caused to be discharged due to their own fluidity.
If you encounter such problems, you can first observe whether there is a serious drawing between the waste side and the label. If the drawing phenomenon is more serious, it means that the coating amount of the adhesive is large or the fluidity is strong. This problem can be solved by applying some silicone oil auxiliaries on the die cutter or heating by the electric heating rod. The silicone oil additive can effectively slow down the rate of adhesive backflow, and heating the self-adhesive material can soften the adhesive quickly, thereby reducing the degree of drawing.
5. Die cutting tool defects lead to waste edge breakage
The die cutter has defects and is easy to cause the waste edge to break. For example, a small gap at the edge of the knife edge may cause the self-adhesive surface material to be completely cut off, and the uncut portion is more concentrated than other parts, and is easily broken. This phenomenon is easier to judge because the location of the fracture is fixed. In such cases, the damaged die must be repaired first and then used for die cutting.