Lamination failure and troubleshooting
Due to factors such as material, process, equipment, environment, etc., the film lamination will appear blistering, wrinkling, ink removal, and film removal. Let's talk about how to avoid these phenomena.
Anhui Huaibei Daily Printing Factory sells tens of thousands of tons of liqueur wines all over the country every year, with a large amount of packaging film and high quality requirements. Due to various reasons, the following abnormal phenomena will occur.
1. After coating, there are bubbles, wrinkles, or even peeling. After research and analysis, it is found that the reasons are roughly as follows:
1. There is a problem with the printed material itself
If the paper with poor uniformity is used for printing, the size and speed of the ink absorption of the paper are inconsistent, which will cause quantitative changes in the paper tightness, uniformity, smoothness and moisture. If the ink is mixed too thick and the ink layer is too thick, the adhesive's wetting, diffusion, and penetration capabilities are poor, the molecular motion is not very active, and the mechanical binding force is small. In addition, in printing, in order to avoid printing sheet paste, often add dry oil to the ink to make the ink layer quickly film, causing the surface of the ink layer to crystallize, the surface of the printed product is smooth, tough, loses adhesion, the adhesive can not Wetting affinity seriously affects the adhesion fastness, which leads to the failure of coating.
2. Influence of operation process and printing environment on the quality of film
When coating the printed matter, first apply a layer of adhesive on the surface of the plastic film. Although it does not meet the requirements of the coating after drying, at this time, the adhesive should be diluted with solvent to achieve quick drying. If the moisture content is too high, bubbles are likely to appear when the coating is pressed, causing peeling and peeling. At the same time, if the laminating workshop does not control the temperature, airflow, and humidity, the film is easy to absorb grease, moisture, dust and other substances in the air, thereby reducing its surface energy. 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 it impossible to attach the film. Uneven pressure of the roller, dry rubber roller itself, and dirt on the rubber roller will also cause the film to wrinkle.
Second, the situation of poor adhesion and troubleshooting
1. If the adhesive is not properly selected, the amount of glue is set incorrectly, and the proportioning measurement is incorrect, the type and amount of adhesive should be reselected.
2. The diluent contains alcohol and water that consume NCO groups, so that the hydroxyl groups do not react. High-purity ethyl acetate should be used.
3. There is dusting on the surface of the printed matter. Wipe gently with a dry cloth.
4. The ink layer of the print is too thick. Should increase the amount of adhesive coating, increase pressure.
5. The ink layer of the printed matter is not dry or dry. It should be hot pressed once before gluing; choose adhesive with high solid content; increase coating thickness; increase drying tunnel temperature, etc.
6. When the adhesive is absorbed by the printing ink and paper, the coating amount is insufficient. Should re-formulate and set the coating amount.
7. The surface treatment of the plastic-adhesive film is not enough or exceeds the applicable period, which invalidates the treatment surface.
8. The pressure is low, 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.
3. The blistering phenomenon generally occurs in the following situations:
1. The printing ink layer is not dry. It should be hot pressed once before gluing, postponing 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. If the drying temperature is too high, the surface of the adhesive will peel. 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, and the film is uneven or curled. The film should be replaced and the tension adjusted.
6. Dust impurities on the surface of the desert. It should be cleared in time.
7. The adhesive coating 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 amount is uneven. Thinner should be added to reduce the adhesive concentration.
Four, film wrinkle
1. The film transfer roller is unbalanced. The transfer roller should be adjusted.
2. The ends of the film are inconsistently tight or wavy. Qualified film should be replaced.
3. The adhesive layer is too thick, the solvent does not evaporate completely, which affects the viscosity. When pressed by the pressure roller, the paper slips between the film and the film. The amount of glue should be adjusted to increase the drying tunnel temperature.
4. The electric heating roller and the rubber roller are unbalanced at both ends, the pressure is inconsistent, and the line speed is not equal. Two rollers should be adjusted.
The problems often encountered in packaging film lamination include these categories. Lamination is an important post-printing process, and packaging printing is a comprehensive issue.
Foshan Liqia Hardware Products Co., Ltd. , https://www.liqiamei.com