Problems in flexible letterpress printing

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1. Adhesion problems. The adhesion is not good, and the ink film is easily peeled off after rubbing. Requires careful selection of resin, use of ink with better adhesion, do not adjust the ink to be used too thinly, or cover the surface of the printed product with protective varnish to meet more and more various packaging. The problem of adhesion of plastic film for printing.

2, through printing. Since the ink penetrates too deeply, the print can be seen on the back side of the paper. It is necessary to replace the thicker ink, reduce the printing pressure, and reduce the amount of ink.

3. Chemical pinholes. It mainly appears on the cellophane printing of moisture proof. There are many pinhole-like blank areas in the ink film. The distribution of pinholes is messy and the size is not uniform. Special additives to improve the wettability of the ink can be added, a small amount of plasticizer and appropriate solvent can be added, or the temperature in the printing shop can be increased, the humidity can be lowered, and new ink can be used instead.

4. Mechanical pinholes. This is caused by a number of reasons, a uniform size of sand holes that spread evenly throughout the print. Increasing press pressure, correcting the ink roller, increasing ink viscosity, and reducing ink dryness can all solve such problems.

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