Common quality problems of laminating film after printing

1. Problems with printed materials

Paper as a printed matter, its own properties, the performance of ink, the density of printed graphics, etc., all affect the quality of the film. If the paper with poor uniformity is used for printing, due to the inconsistency of the size of the ink absorption and the speed of absorption within the format; it will cause quantitative changes in the paper tightness, uniformity, smoothness and moisture. If the ink layer is too thick or too thick, the adhesive molecules will have poor wetting, diffusion, and penetration capabilities, and the movement of the molecules will be less active, and the mechanical binding force will be smaller. In addition, in the printing process, in order to prevent the printed matter from scumming, kerosene is often added to the ink to quickly form a film on the ink layer, causing the surface of the ink layer to crystallize. Wetting affinity, seriously affect the adhesion fastness.

2. The impact of process operation and printing environment on the quality of the film

When coating the product, first apply a layer of adhesive on the surface of the plastic film, although after drying, it still can not meet the requirements of the coating. At this time, it is necessary to increase the concentration of the solvent to dilute the adhesive for quick drying, but the moisture content is too high, and air bubbles are likely to appear when the film is pressed, and then peeling and peeling off. At the same time, the film is easy to absorb grease, moisture, dust and other substances in the air, thereby reducing its surface function. Excessive humidity will also affect the evaporation of the solvent in the adhesive. Too much residual solvent will cause air separation in the film, making the film unable to stick. At the same time, uneven roller pressure, uneven rubber rollers, and dirt on the rubber roller will cause wrinkling during lamination.

How to eliminate the above faults?

1. Bad bonding situation

1. Improper selection of adhesive, improper setting of glue amount, incorrect proportioning measurement. The type and amount of adhesive should be reselected.

2. The diluent contains alcohol and water that consume NCO groups, so that the hydroxyl group of the main agent does not react. High-purity ethyl acetate should be used.

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

4. The ink layer of the printed matter is too thick. The adhesive coating arrangement should be increased to increase the pressure.

5. The ink layer of the printed matter is not dry or completely dried. It should be hot pressed once before gluing; select the adhesive with high solid content; increase the thickness of the adhesive coating; increase the temperature of the drying tunnel, etc.

6. The adhesive is absorbed by the printing ink and paper, which makes the coating amount insufficient. Should re-formulate and set the coating amount.

7. The surface treatment of the plastic film is not enough or exceeds the applicable period, making the treatment surface invalid. The plastic film should be replaced.

8. The pressure is too small, the vehicle speed is fast, and the temperature is low. The temperature and pressure of the film should be increased, and the vehicle speed should be appropriately reduced. [next]

2. Foaming

1. The printing ink layer is not dry. It should be hot pressed again before gluing; postpone the filming time and let it dry completely.

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

3. The drying temperature is too high, and the surface of the adhesive skins. The drying temperature should be reduced.

4. The surface temperature of the composite roller is too high. The temperature of the composite roller should be reduced.

5. The film is wrinkled or slack, the film is uneven or curled. The film should be replaced and the tension adjusted.

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

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

8. The adhesive concentration is too high, the viscosity is large, and the coating is uneven. Use thinner to reduce adhesive concentration.

Third, the film wrinkles

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

2. Inconsistent elasticity or wavy edges at both ends of the film. Qualified film should be replaced.

3. The glue layer is too thick, the solvent does not evaporate completely, which affects the viscosity. When pressed by the pressure roller, the paper and the film slip. The amount of glue should be adjusted to increase the temperature of the drying tunnel.

4. Both ends of the electric heating roller and the rubber roller are unbalanced, the pressure is inconsistent, and the linear speed is not equal.

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