Drying of water-based plastic ink

Sun Yat-sen University is one of the earliest universities in China involved in the research and development of gravure plastic ink. As early as in 2000, the Guangdong Province Science and Technology Innovation Project 100, chaired by the Institute of Polymer Research of the School of Chemical Engineering, passed the provincial appraisal of Water Gravure Printing Ink for Food Packaging and Printing. Cooperated with Zhuhai Ruilong Ink Co., Ltd. (the second finisher), won the third prize of Guangdong Provincial Science and Technology Progress Award in 2001; the “waterborne plastic composite ink cleaner production technology” cooperating with Guangzhou Zhujiang Chemical Industry Group passed the provincial scientific and technological achievement appraisal and has been invented. Patent, authorized notice number CN1233759C. In mid-August this year, the journalist visited the Ink/Paint Research Center of the Institute of Polymer Research, School of Chemistry, Sun Yat-sen University, and interviewed Associate Professor Wang Xiaomei who has been engaged in the research and development of gravure printing plastic water-based inks. He hoped to get some inspiration from the academic community. Latest news.

Now the packaging and printing industry is not widely used, and Qingdao, Tianjin, Guangdong Xinhui, Foshan and other places are useful. Many printing companies are now paying attention to this product. Only a few ink factories are producing water-based plastic inks. I have seen related products abroad.

The adhesion of ink and ink has already met the printing requirements, and now it is only a matter of slow printing and drying speed and printing adaptability. The foreign printing presses have a long drying path, while the domestic printing presses generally have a drying path of only about 2 meters, which is not very good.

One of the biggest obstacles in the application of gravure plastic ink is the quality of the product, and the other is the problem of the equipment. Comparing with the effect of solvent-based inks, there is still a gap between gravure printing inks, but the gap is getting smaller and smaller. There is also a more important issue of consumer attitudes in terms of health, environmental protection, and beautiful prints. It may be that the printing effect of ink and wash is acceptable in the world because of environmental protection and non-toxicity. It is difficult to accept at home and customers will not be satisfied.

The specific application of ink in printing companies, I think the speed of printing is still a problem. For printing companies, the main reason is the low efficiency of printing, which is related to printing equipment. Our test results: BOPP film is printed on a 2m long drying tunnel at a drying temperature of 60°C. The printing speed is about 30 m/min. BOPP film is printed on a machine that is 8m long and the printing speed can reach over 80 m. /min. If the temperature of the drying tunnel is increased, the printing speed is improved, but above 80°C, the PE film is easily deformed.

In addition, the issue of cost is that the price of water-based plastic inks is more than 10% higher than that of current gravure inks containing toluene, but the price is flat compared with the alcohol ester-type polyurethane inks. Due to the high solid content of the ink, the same area is printed and the amount of ink used is about 10% less.

In the aspect of plate making, proper improvement should be made in the angle of engraving.

Drying mainly changes the drying method. At present, infrared drying and electric heating are the main methods. I think it might be better if microwaves are used, not only drying fast, but also not damaging printed substrates.

All plastic substrates can be applied with gravure plastic ink. In principle, it is also applicable to the printing and packaging of high-temperature cooking bags. It is mainly that the surface tension of the ink is matched with the surface of the substrate. The resin is the heart of the ink. Determines the adhesion to the substrate. It is ideal for the substrate surface to reach 44 dyne. According to our tests, there is good adhesion on PET, PVC, BOPP, PE.

The quality of the product at the time of printing is directly related to the performance of the ink. At present, the domestic plastic ink and solvent-based ink, the gloss has been better, a little less vivid; in terms of adhesion, in the PVC, PET, pure aluminum foil and other substrates on the good adhesion, but in the nylon substrate The adhesion will be lower.

Gravure printing plastic ink in the application process is more complicated, because with water as a diluent, the surface tension of water is relatively large, the need for some surfactant to adjust the tension, which involves the balance between additives, ink performance The problem is that the required technical difficulty is relatively high. For example, if you want to adjust the pH value, the pH value can not be seen with your eyes, and you need to use the instrument to measure. This gives the front-line operators a relatively high technical requirement and responsibility.

Water-based ink is the only ink approved by the US FDA at present, and it should be the trend of market development. I think the alcohol-soluble ink is a transitional ink and it should gradually move towards water-based ink. Of course, this requires printing equipment, packaging, printing, and plate making. And ink companies work together in four areas. Now some domestic film production companies produce olefinic films with polarity itself, the surface energy is relatively high and does not require corona treatment, which is more suitable for water-based ink printing. I think the prospects for the gravure plastic ink market are good.







Source: Ink News