Ink drying is basically caused by the following:
1. The old printing was not cleaned.
2, the solvent drying speed is too fast (printing speed and solvent evaporation rate does not match).
3, dry hot air hit the layout.
4. When the contact points of the scraper and the plate surface are mixed with dust, moisture, air bubbles, etc. in the printing ink, the ink transfer rate will decrease due to the decrease of the actual ink volume in the cell site. Some coarser particles may even be embedded in the ink. Within the cyberspace.
5. The precision and angle of electric engraving of the network points at the time of plate making will also be affected.
6, the transfer to the ink, causing the network is not enough or lost.
7. The quality of ink and solvent is also one of the causes of blockage. If the fluidity of the ink is not good, the printing viscosity is too high, the ink has been degraded or mixed into different series of inks, an inappropriate solvent or solvent ratio is used. Even improper operation when adding solvent inks will affect the transferability of the ink, resulting in blockage. The influence of the active particles: When printed for a certain time, the ink produces many reactive groups that bind to the chromium ions of the printing roller. When these binders are in the shallow part of the graded version, their binding force is hindered. Ink transfer to the substrate, causing blockage. The basic performance is: shallow screen version of the flower.
To solve these problems, we can add a slowing agent (such as CHY-1 printing aid) to the ink. Leakage is mainly caused by the pressure roller, film, improper operation and other reasons: the roller is uneven or there is a bubble will cause serious leakage phenomenon. Film corona or contaminated during use, causing localized corona insufficiency. The amount of ink in the ink tank is insufficient, and the printing roller has a partial lack of ink. A hard object stuck under the printing blade, scraping off the ink and causing the ink mark scraper. Imprinting due to blocking or ink loss. There are many reasons for the adhesion and peeling of the ink. Everyone generally considers the ink, film, and solvent residues, ignoring the mismatch between the temperature and the air volume during drying, the false drying phenomenon caused by the low temperature and high air volume, and insufficient cooling of the printed film after drying. These two points. European and American countries have higher requirements for solvent residues, and the benzene content is generally not more than 0.5 mg/m2. With the current printing level in our country, it is very difficult for the benzene content to be lower than 2mg/m2. Residues of solvents mainly exist in the process of printing and dry recycling, while benzene solvents are mainly caused by printing residues. If the drying tunnel of the dryer is long and the drying capacity is sufficient, sometimes the residual solvent of the printing will be volatilized. Therefore, we will mainly discuss the problem of residual printing solvents.