label The technology of the printing industry is constantly innovating, and flexo, offset and digital printing are all splendid, and there is a constant call for “enterprise transformation, equipment upgrade to flexo printing ”, “transformation to the Internet, digital printing ”. The top printing of the label printing market is dominated by people. Does embossing really have to exit the label printing stage? Where do you go from here? The author will make a simple analysis of his own practical experience.

The advantage of embossing in the field of label printing is still

In the label printing industry, the advantages of embossing still exist, mainly in the following three aspects.

Production process advantage

At present, the commonly used processes for self-adhesive label printing include back printing, offset printing, cold stamping, multi-layer label composite printing, rotary screen printing, reverse varnish, hydrogel coating, wire coating, die cutting and various Printing technology combination process, etc., these processes can be realized on the full-rotation embossing machine. Moreover, the type of process that can be connected at the same time on a embossing machine is second only to the flexo press, and the offset press has almost no process to be connected.

Printing equipment advantage

Compared with the label flexo printing machine and the label printing machine, the price of the embossing machine is low, the technology is mature, the manufacturer has many, the maintenance is convenient, and the cost of the accessory is low. The price of the three kinds of equipment is the lowest with the embossing machine, the second is the offset printing machine, and the highest is the flexo printing machine.

Print effect advantage

Comparing the three printing methods, the embossed ink layer thickness and overprinting precision are between flexo and offset printing, and the dot reproduction effect is second to flexo and offset printing, but with the maturity of CTP plate making technology, the application of HD dot, regardless of Whether the embossed plate or the flexographic plate is close to offset printing on the dot reproduction. The characteristics of the embossed ink are good, so the printed labels, especially the battery labels of the matte oil, have obvious advantages in performance tests such as friction resistance, scratch resistance and alcohol resistance.

How to improve the label embossing

Inevitably, there are some common problems with embossing, and the author will list the solutions to these problems accordingly.

Overprint problem

Label printing companies want to accurately print the product, be sure to put the plate on the positive and evenly apply the plate, do not diagonally pull the plate (see Figure 1), otherwise it will affect the product overprinting effect and the life of the plate. Even for presses with a cable-stayed station, the plate should be positive, because the unit will reduce the overprinting accuracy of the device as a whole. Then pay attention to the precise adjustment of the printing pressure, the pressure should be as small as possible while ensuring that the printed content is not too good, but it must be locked to prevent the pressure from falling.

The most difficult problem of overprinting is the product with four-color anti-white characters. The smaller the printing of such words, the more difficult it is to overprint. In view of this situation, the pre-press production process should pay attention to bleeding, you can change the four-color anti-white to three colors, to black or cyan. Of course, if you can use two-color printing, you can change the four primary color plates into a special color version if necessary. In short, you must handle it well before printing.

If there is an overprint error in the horizontal direction of the printing (ie, the paper feeding direction of the equipment), which is often referred to as the “short version” phenomenon in the industry, it is possible to increase the printing pressure and increase the printing speed of the short unit. This operation can usually make up for it. Error below 0.2mm. If the longitudinal overprinting of the layout is not allowed, most of the materials are caused by heat shrinkage. In this case, the curing lamp can be replaced with a high-quality UV lamp, or the UV lamp box can be cleaned to keep the exhaust air smoothly and reduce the temperature of the light box. Pay special attention to the UV lamp quartz plate must be cleaned regularly to maintain high light transmittance. UV lamps can also have a good curing effect at low power. The low temperature of the light box is good for overprinting and prolongs the life of the lamp and saves energy.

Chromatic aberration problem

The letterpress and PS printing presses are inked by the top of the ink fountain, and the multiple rubber rollers are used for ink transfer. In high-volume printing, the rubber roller generates heat, which causes the temperature of the ink set to rise, which in turn causes the rubber roller to expand and the viscosity of the ink to decrease. Finally, the color difference of the product is directly caused. So we have to pay attention to the following points.

1. Always print the ink before starting the printing (ie, the equipment is idling) for 15 to 30 minutes.

2. In the case of mass production, if the ink of the ink fountain is reduced, the amount of ink in the ink will also be affected. Therefore, it is necessary to add ink to keep the ink volume of the ink fountain 2/3 better. At the same time, it is necessary to stir the ink with the ink shovel to keep the ink good and stable. Mobility.

3. In the case of factory conditions, the workshop environment should maintain a temperature of 20 ° C ~ 30 ° C, humidity 50% ~ 70% is appropriate.

Dirty problem

When printed products frequently appear irregular spots, it may be caused by the following reasons.

1. The ink set ink is dirty. In this case, you can use a self-adhesive rubber surface to stick to the plate roller to see if there is any dirty spots and paper hair in the transferred ink (see Figure 2).

2. The surface of the printing material is dirty. In this case, it is necessary to see whether the dust removing roller is covered with dust. If the dust removing roller is cleaned, the humidifying device can be used to humidify the printing material before the dust removing station, and then the static electricity can be used to remove the static electricity on the surface of the material, which will effectively solve the problem ( See Figure 3).

3. If there is a white dot printed inaccurately and densely, it is caused by the explosion of ink molecules caused by static electricity, which can be solved by placing the static cord on the printing material before placing it on the ink set (see Figure 4).

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Snow King Fei (Guangdong) Biomedical Technology Co., Ltd. ,