Failure and elimination in the laminating process

Failure and elimination in the laminating process

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Due to materials, processes, equipment, environment and other factors, the film may appear foaming, wrinkling, deinking, and film removal. Let's talk about how to avoid these phenomena.

First, the reasons for the failure:

  1. There is a problem with the printed material itself

If you use a paper with poor uniformity, the amount and speed of paper suction will be inconsistent, which will result in quantitative changes in paper tightness, uniformity, smoothness, and moisture. If the ink is too thick and the ink layer is too thick, the adhesive will have poor wetting, spreading, and penetrating ability, the molecular motion is not very active, and the mechanical bonding force is small. In addition, in printing, in order to avoid the printing paste, the drying oil is often added to the ink to make the ink layer quickly conjunctinate, causing the surface of the ink layer to crystallize, the surface of the printed product is smooth, tough, and the adhesive force is lost, and the adhesive cannot be combined with the same. Wetting affinity affects the bond fastness, which leads to failure of the film.

2. Effect of operating process and printing environment on film quality

When coating the printed film, first apply a layer of adhesive on the surface of the plastic film. Although it has not been cured after drying, the adhesive should be diluted with a solvent to achieve quick drying. If the moisture content is too high, air bubbles are likely to occur during pressure filming, resulting in peeling and falling off. At the same time, if the laminating workshop does not control the temperature, airflow, and humidity, the film easily adsorbs oil, moisture, dust, and the like in the air, thereby reducing the surface energy. Excessive humidity can also affect the evaporation of solvents in the adhesive. Too much residual solvent will create air isolation in the film, preventing the film from sticking. The roller pressure is not uniform, the rubber roller itself is not dry, there is dirt on the rubber roller, and the coating film wrinkles.

Second, the situation of poor adhesion and troubleshooting

1. If the adhesive is improperly selected, the amount of glue applied is improperly set, and when the ratio is incorrectly measured, the type and amount of the adhesive should be re-selected.

2. The diluent contains an alcohol and water which consume an NCO group, so that the hydroxyl group does not react. High purity ethyl acetate should be used.

3. There is dusting on the surface of the print. Gently wipe off with a dry cloth.

4. The ink layer of the print is too thick. The amount of adhesive applied should be increased to increase the pressure.

5. The ink layer of the print is not dried or dried. It should be hot pressed and then smeared; select a binder with a high solid content; increase the coating thickness; increase the temperature of the drying tunnel.

6. When the adhesive is absorbed by the printing ink and the paper, the amount of coating is insufficient. The formulation should be re-formulated and set.

7. If the surface treatment of the plastic-adhesive film is insufficient or exceeds the applicable period, the treated surface is invalid, and the plastic-adhesive film should be renewed.

  8. The pressure is too small, the speed is fast, and the temperature is low. The film temperature and pressure should be increased to reduce the speed of the vehicle appropriately.

Third, the occurrence of blistering, generally belongs to the following situations:

1. The printing ink layer is not dry. It should be hot pressed first and then glued, delaying the filming time and making it completely dry.

2. The printed ink layer is too thick. The amount of adhesive applied should be increased to increase the pressure and compound temperature.

3. The drying temperature is too high and the surface of the adhesive is crusted. The drying temperature should be lowered.

4. The surface temperature of the composite roll is too high. The composite roll temperature should be lowered.

5. The film has wrinkles or slacks, and the film is uneven or curled. The film should be replaced and the tension adjusted.

6. There are dust and impurities on the surface of the desert. It should be cleared in time.

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

8. The binder concentration is too high, the viscosity is large, and the coating amount is not uniform. A thinner should be added to reduce the binder concentration.

Fourth, the film wrinkles

1. The film transfer roller is unbalanced. The transfer roller should be adjusted.

2. The ends of the film are tightly inconsistent or wavy. The qualified film should be replaced.

3. The glue layer is too thick, the solvent evaporation is not thorough, affecting the viscosity, being squeezed by the pressure roller, and slippage occurs between the paper and the film. The amount of glue should be adjusted to increase the temperature of the drying tunnel.

4. The electric heating roller and the rubber roller are unbalanced at both ends, the pressure is inconsistent, and the linear speed is not equal. The two rollers should be adjusted.

The problems that are often encountered in packaging printed film coatings include these categories. Film coating is an important post-printing process, and packaging printing is a comprehensive problem.