Introduction to the most popular film covering pro

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Introduction to the advantages of film coating process and water-based film coating

water-based film coating is an effective means to process the surface of printed matter, improve the gloss and intensity of printed matter surface, increase new luminous materials, improve the efficiency of packaging and sorting in plastic recycling, strengthen aesthetic effect, and improve the grade and commodity value of printed matter. Therefore, to measure the quality of film coating, we also need to evaluate the brightness, intensity Cohesion and other aspects

The development of water-based laminating machine has greatly promoted the application of water-based laminating technology. Water-based wet laminating is favored by customers because of its high strength, high grade, easy recycling, pollution-free and other characteristics of laminating prints

when the water-based film coating process was just promoted, because customers didn't know much about this process, they were worried about it and were afraid of problems. In view of this, a lot of tests had been done for customers in advance. For example, Hubei Xinhua printing factory, in order to test the temperature, humidity and oil resistance of printed matter after water-based film coating, relevant film coating tests had been done at the early stage of machine use, and the requirements of film coating products could be met regardless of temperature, humidity and oil resistance

the film coating process is complex, and the following problems still need to be paid attention to in normal production:

printing powder spraying

because water-based glue can dissolve the powder spraying on the surface of printing materials, it is incomprehensible when snowflakes appear on the film coated products. In fact, the reason is very simple. The water-based glue itself is also limited by solubility. If the powder spraying on printing materials is too large, the excess part cannot be completely dissolved by glue, Large areas of snowflakes will appear

there are three ways to solve this situation:

1. Coordinate the upper and lower processes, and minimize the amount of powder sprayed during printing

2. the amount of glue should be appropriately increased to increase the ability of glue to dissolve and spray powder

3. Clean the surface of the printed matter with suspended powder before laminating


because the water-based coating improves the economic efficiency, the film adhesive dries quickly. If it is still and does not flow, it will dry into rubber and solid blocks. If it is attached to the gluing roller or pressure roller, it will cause local gluing to be too small, or local pressure to be too large when applying pressure. Therefore, during the film covering process, keep the rubber coating roller and pressure roller clean

if there is too much dust in the surrounding environment, such as dry rubber and cut film fragments in the glue, the film coated products will have snowflakes, so attention should be paid to environmental hygiene. If the glue is not used up, it should be poured back into the glue barrel to seal it, or the method of filtration before gluing should be adopted

printing discoloration

it mainly occurs in large-area gold printing and bronzing products. This is because glue includes hydraulic universal testing machine and electronic universal testing machine. 1. Automatic calibration: the system can automatically calibrate the accuracy of indication; Elements react with gold powder

the solution is: for gold printing products, use special gold ink or special glue, or change the process. Bronzing products are coated first and then bronzed. Many manufacturers use the latter process, and the effect is very good

paper plastic separation

this phenomenon is easy to appear in full page prints. Due to the thick ink layer on the surface, the glue is difficult to wet, diffuse and penetrate, and the bonding is not firm

the solution is:

1. For this product, the glue manufacturer is required to increase the solid content of the glue

2. Appropriately increase the thickness of the adhesive coating

3. Increase the outside temperature during film covering and product drying

4. Check whether the glue is deteriorated, and check the ex factory date and shelf life of the glue

5. Whether the film exceeds the shelf life, and check whether the corona treatment of the film is invalid


there are several reasons for this:

1. Too much glue, because a large amount of glue will inevitably make the paper absorb more water. Any paper will deform when it absorbs a lot of water. Therefore, in the absence of snowflakes, try to reduce the amount of glue

2. If the stretching deformation of the film is serious, the tension of the film should be properly adjusted at this time. As long as the film can be flat and fit with the paper, the smaller the tension is, the better

3. the winding tension is too large. On the premise of ensuring that the product can be rolled onto the roll after covering, the smaller the tightening force, the better

4. the temperature difference and humidity difference of the external environment where the film is located are too large

at present, there is also a kind of glue between oil and water in China. The price is very cheap. It does not need to be dried. After coating, it will dry naturally. The brightness and flatness of the coated product can meet the requirements, but it has a strong pungent smell and unstable quality. It can be used for low-grade products. For high-end products, it is recommended to use white environmental protection glue produced by regular manufacturers

with the rapid development of printing and packaging industry, water-based lamination will have a broader prospect

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