Common faults of cover coating process in book printing --- Poor adhesion

1. Improper selection of adhesive, improper setting of gluing amount and wrong proportioning measurement. The adhesive model and coating amount shall be re selected for accurate preparation.

2. The diluent contains alcohol and water that consume hydroxyl, so that the hydroxyl of the main agent does not react. High purity (995%) ethyl acetate shall be used.

3. There is powder spraying on the surface of book printing. Wipe gently with a dry cloth.

4. Printing ink layer is too thick. Should increase the amount of adhesive coating, increase the pressure

5. The ink layer of printed matter is not dry or not completely dry. It shall be hot pressed before gluing; Select adhesives with high solid content; Increase the adhesive coating thickness; Increase the temperature of drying channel, etc

6. The adhesive is absorbed by printing ink and paper, resulting in insufficient coating. The formula and coating amount shall be reset

7. The surface treatment of plastic film is insufficient or exceeds the applicable period. The set formula and application amount shall be updated.

8. The pressure is low, the speed is fast, and the temperature is low. The coating temperature and pressure shall be increased and the vehicle speed shall be reduced appropriately.

Common faults of cover coating process in book printing--- bubbled

1. The printing ink layer is not dry. It shall be hot pressed before gluing; Delay the coating time to dry it thoroughly.

2. The book printing ink layer is too thick. Should increase the amount of adhesive coating, increase the pressure and coating temperature

3. If the drying temperature is too high, the surface of the adhesive will be skinned. The drying temperature should be reduced

4. The surface temperature of the compound roll is too high. The compound roll temperature shall be reduced.

5. If the film is wrinkled or loose, if the film is uneven or crimped, replace the qualified film and adjust the tension.

6. Dust and impurities are wrapped on the surface of the film. It shall be removed in time.

7. The adhesive coating is uneven and the amount is small. The coating amount and uniformity should be improved.

8. High adhesive concentration, high viscosity and uneven coating. Use diluent to reduce the viscosity of adhesive.