At present, sticker label has been more and more widely used in the field of packaging in China. Below, lianyintong will share with you a few sticker printing process encountered problems and solutions, I hope to help you.

Hot melt adhesive adhesive material

Lianyitong is a label printing enterprise. In this factory, there was a phenomenon that the double-sided label printed in front four-color and single-color on glue surface "shifted" after it was placed for a period of time. The label's specific production process is: first in the front of the adhesive material printing four-color pattern, and then the backing paper opened, printed on the surface of the text instructions, and finally with the backing paper composite and die cutting molding. When the label was first printed, there was no problem, but after a period of time, it was found that there was a "shift" phenomenon in the printed text on the glue surface, which was manifested as: some punctuation marks were out of place, and some words became blurred, leading to a large number of finished labels being scrapped.

After the united press survey, the selection of hot - melt coated paper adhesive materials. However, the problem is precisely in the adhesive. Because of the strong fluidity of hot melt adhesive, if this layer of the surface of the printing of small text, after the composite, die-cutting process once the label has a small displacement, adhesive will follow the flow, resulting in printed on the text has a small displacement and deformation or fuzzy.

Therefore, it is suggested that label printing enterprises should not choose hot melt adhesive materials with strong fluidity, but choose water-sol materials with weak fluidity. At the same time need to pay attention to, even if the selection of water-sol materials, also want to pay attention to the coating thickness of the rubber layer. Because whether it is hot melt adhesive or hydrosol material, if the adhesive coating is too thick, it may lead to a slight flow of adhesive, resulting in printing on the small text deformation. In general, the printing of such live parts, water-soluble adhesive coating weight should be around (18 1) grams.

Sticker label folding is not neat, askew

Once, when printing a folding label, lianyintong found that the deviation of the label was quite serious after folding, and I began to suspect that it was just the tension of the equipment, but no matter how to adjust the tension of the equipment, it was of no help. Finally, lianyintong found the cause of the problem and successfully solved the problem, which is summarized as follows.

1. Causes and solutions of irregular label folding

The main reason for the irregular label folding is the tension of the equipment. Equipment tension instability will cause the die-cutting process of the position of the die-cutting knife before and after swing, resulting in irregular folding. This causes uneven folding, and the folded labels are serrated. In this case you can try to increase the running tension of the equipment, if there is a pressure roller in front of the die-cutting position, be sure to press the roller and ensure that the pressure on both sides of the pressure roller. Generally, the above adjustment can solve this problem, but if it still cannot be solved, the equipment supplier shall be invited to help solve the problem.

2. Causes and solutions of label folding skew

Label folding skew is divided into two cases, one is before and after the skew, the other is left and right skew. Front and rear skew is generally due to die - cutting knife roller diameter and theoretical value error. For example, the diameter of a 130-tooth knife roller should be 412.75mm in theory, but sometimes there is an error, and the actual size will be larger or smaller than this value. This will lead to the top of the dotted line folding knife can not be evenly divided, resulting in the label folded before and after the skew.

The left-right skew is generally caused by the skew of the dotted line knife, and sometimes the left-right skew appears in the folding. At this time, you just need to adjust the dotted line knife. But there is a point to pay attention to, that is sometimes we visually observe the dotted line knife is positive, but the actual cut out of the label is oblique, the occurrence of this situation may be the equipment of the die cutting machine unit skew, or die cutting knife roller skew. If this happens, the equipment needs to be adjusted.

Hot melt adhesive adhesive materials in winter die - cutting flight mark

Hot melt adhesive material in winter is particularly prone to die cutting flying mark phenomenon, the so-called die cutting flying mark is in the die cutting when the label will be along with the waste side is lifted. If there is a slight phenomenon of flying mark, label printing enterprises will cause a certain amount of material waste; If the flyer is more serious, it can't be produced normally. Causes of hot melt adhesive materials in winter die - cutting targets are mainly the following.

1. The parting force of hot melt adhesive decreases under the influence of temperature

Hot melt adhesive material has a feature is greatly influenced by temperature, under normal circumstances, the workshop temperature below 15 ℃, hot melt adhesive material of mold force will decrease rapidly. So in the north of China in winter, hot melt adhesive materials are particularly prone to die - cutting flying mark problems.

2. Hot melt adhesive itself has low parting force

If the hot melt adhesive itself out of the mold force is low, then in the summer die cutting may not be a problem, but in the winter it is easy to die cutting fly mark problem.

3. Glue drawing and reflux

Hot melt adhesive is also a feature of strong liquidity, die cutting at normal temperature, hot melt than water glue more easily wiredrawing and reflux. In other words, hot melt glue is more likely to stick to the exhaust side, resulting in a flying beacon.

In view of the above reasons for the die-cutting flying mark phenomenon, lianyintong to introduce a relatively simple but very effective method, that is heating method.

The specific method is to try to fix an electric heating rod on the equipment and install it in front of the waste roller in the waste discharge station. The purpose of this is to let the adhesive material in the waste side before the heat. After fixing the heating tube, you can manually test whether the temperature of the material has increased to a certain extent before discharging. This can effectively improve the hot melt adhesive materials in winter die cutting flight mark problem. Because the hot melt adhesive in the heat after the release force will quickly rise, so that the surface paper and the substrate between the binding force increased, it is not easy to appear with the exhaust side of the stripping phenomenon. At the same time, heating can also reduce the adhesive wire drawing, backflow, and the waste side of the adhesion, because in the heat of the moment the adhesive will become soft, pulled out of the glue is more likely to fracture.