Screen Printing Faults and Countermeasures - Sticky Pages

XIV. Sticky pages

In the accumulation process of screen printing products, adhesion failures may occur between the printing sheets, which is also called adhesion failure. Adhesion can cause print quality problems and even scrap. The main reasons for the occurrence of adhesions are the following:

After printing, the printing ink is not dry enough. When the ink is not dried, the prints are piled up and piled up, causing smearing and blocking.

The improper selection of the constituent materials of the screen printing ink is also the cause of the adhesion between printed materials. When the softening point of the synthetic resin film forming material in the ink is low or the volatility of the ink is not good, blocking occurs. In general, a thermoplastic resin is used for the evaporative drying ink, and the resin has poor heat resistance. If the solvent remains on the ink film after printing, the ink film will soften, causing the print to stick. Especially in the summer, due to the relatively high temperature, the adhesion between prints is likely to occur.

The ink used for printing has a certain dissolution effect on the substrate, and it also causes adhesion between the printed materials. Some of the solvents used in printing are very soluble to the substrate. When printing, the ink produced a certain amount of dissolution on the surface of the substrate. At this time, although the surface of the ink has dried, the contact portion between the ink and the substrate has not yet dried out, and adhesion phenomenon will occur under the action of the gravity. When the substrate is a soft vinyl material, part of the plasticizer in the vinyl material after printing is transferred to the ink film, resulting in softening of the ink film and also causing blocking.

In order to prevent adhesion, first select the ink and solvent that are suitable for the substrate. Secondly, ink with faster drying speed is selected, and sufficient drying is taken care of. Strictly follow the process requirements. General glossy inks are prone to blocking, so pay full attention.

Scraper rubber strip wear, the blade was rounded, resulting in thickening of the ink film scraping, or printing pressure is too large, ink film thickening, can also cause adhesion failure.