Analysis of poor adhesion of the hottest film self

2022-09-21
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Analysis of poor adhesion of film adhesive UV ink

in the market of self-adhesive label materials, the biggest difference between film adhesive materials and paper is that its surface is not absorbent. At present, the vast majority of printing companies use UV ink for printing on film adhesive labels, because UV ink printing can adopt the method of UV instant drying and its good adhesion. Although UV ink has the advantages of fast drying speed, good printing effect, good scratch resistance and solvent resistance, after all, UV ink is a new technology developed in recent years. Customers often encounter some problems in the printing process. The most common problem is the adhesion of UV ink on the surface of thin film materials

I. what is poor adhesion of UV ink

the so-called poor ink adhesion means that the ink is separated from the surface of the film by some test method. According to the different requirements of end users, each customer may have different knowledge about the relevant utilization of fixtures in terms of test methods. In the self-adhesive label printing industry, most customers will use 3M 810 or 3M 610 tape for adhesion test

II. Cause analysis of poor ink adhesion

poor ink drying in actual printing production, customers often encounter UV ink. After UV lamp irradiation, the ink surface has been dry, but the interior is not completely dry. In this case, there is no completely dry ink, and the waste lithium material recycling project will be built in Suining in the later stage. The adhesion on the surface of the film material is relatively weak, so it is easy to tear the ink off the surface of the material when testing with tape

the surface tension of the film material is not enough. Before printing, use a dyne pen or dyne solution to check the surface tension of the PE film material. If you want to ensure good UV ink adhesion, the surface tension should at least reach 42 dyne/cm. If the surface tension does not meet the requirements before printing, it will result in poor ink adhesion

3. The use of ink does not match. For some thin film materials (such as pet, BOPP), in order to enable the material to be printed, the material supplier will process a coating layer on the surface. Because different inks use different resins, printing on the same coating layer often shows different results. When purchasing coated materials, you should consult the material supplier about the ink brand suitable for the material

for the above three situations, we propose the following solutions:

1 To judge whether the ink has been completely dry, we can use the thumb press method, that is, press the thumb firmly on the ink surface, and then press it back and forth several times. If there is ink on the thumb, we can judge that the ink is not completely dry. There are many reasons why the ink is not completely dried. There may be a problem with the ink itself, or it may be a problem with the UV drying system. Here we mainly pay attention to the following aspects:

(1) if the UV ink is not used up, be sure to use the LCD to display the experimental force, displacement, peak value, running state, running speed, etc. in real time, cover the cover well, and pay attention to avoid light when storing. The ambient temperature for storage should be about 20 ℃, not too high

(2) the service time of UV lamp is generally about 1000 hours. Once the UV lamp has exceeded its service life, its spectral curve has changed, and the ultraviolet light emitted does not meet the requirements of drying ink. Therefore, we should correctly record the use time of UV lamp and replace it in time

2. For film materials, we can divide them into two categories in terms of their suitability for printing. One is: materials that need corona treatment to be printed; The other is that the material itself has been processed with a layer of coating that can be printed. For customers, they decide what kind of materials to buy according to the capabilities of their own printing equipment, such as whether there is a corona device that is processed on the machine line. If the customer has a corona treatment unit on the printing machine, they can purchase corona treatment materials. Before printing, we need to measure the surface tension of the material. If it is low, how can we measure it in more detail? At 42 dyne/cm, we must carry out online corona treatment before printing. In this way, good ink adhesion can be guaranteed. If there is already a printable coating on the surface of the material, the customer should consult the material manufacturer and use brand inks, because different coating formulas are suitable for different brands of inks. Only in the case of coating and ink matching, can we solve the problem of ink adhesion

to sum up, if we encounter the problem of ink adhesion of thin film materials in production, we should correctly analyze the causes, so as to find the correct solution to the problem

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