Precautions for the production process of the hott

Precautions for the production process of water-based lamination

water-based lamination is an effective means to process the surface of printing materials, so as to improve the gloss and strength of the surface of printing materials, enhance the aesthetic effect, and improve the grade and commodity value of printing materials. Therefore, to measure the quality of lamination, we also need to examine the brightness, strength, adhesion and other aspects of lamination

the precision of the open ball screw of the water-based laminating machine is the highest, which has greatly promoted the application of the water-based laminating process. The water-based wet laminating is favored by the majority of customers because of its high strength, high grade, easy recycling, pollution-free and other characteristics of the laminating printing

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, The first is to vigorously promote innovation driven development

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

cleaning

because the water-based film covering 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 due to the chemical reaction between the chemically active elements in the glue and the 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 filtering accuracy of the filter reaches 5um, such components have been verified on the experimental system, 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

deformation

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 clamping force is also greater, the film can be flat and fit with the paper, and 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