Several Common Quality Problems of Post-laminated Film (I)

1, the printing material itself

Paper as a print, its own nature, the performance of the ink, the density of printed graphics, etc., all affect the quality of the film. If you use a poorly formed paper to print, due to the size of the ink absorption in the web, the speed of the absorption rate is inconsistent; it will cause the paper tightness, evenness, smoothness, moisture quantitative change. If the printed ink layer is too thick, the adhesive molecules will have poor wetting, diffusion, and penetration. The movement of molecules between them will be relatively inactive, and the mechanical bonding force will be small. In addition, in the printing process, in order to make the prints not to be stenciled, kerosene is often added to the ink, so that the ink layer is quickly congealed, resulting in crystallization of the ink layer surface, the print surface is smooth, tough, loses adhesion, adhesive can not be Humidity and affinity seriously affect the adhesion fastness.

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

When laminating the product, first apply a layer of adhesive on the surface of the plastic film. After the drying treatment, the adhesive cannot meet the requirements for lamination. In this case, the solvent is diluted to increase the concentration of the binder in order to obtain fast drying. However, if the moisture content is too high, bubbles with air are liable to appear when the film is pressurized, and then peeling off occurs. At the same time, the film easily adsorbs substances such as grease, moisture, and dust in the air, thereby reducing its surface function. Excessive humidity can also affect the volatilization of the solvent in the adhesive. Too much residual solvent will produce air separation in the film, making it impossible to stick the film. At the same time, uneven roller pressure, unevenness of the roller itself and dirt on the roller will cause wrinkling when the film is covered.

How to eliminate the above fault?

First, there is a bad situation

1, improper use of adhesives, improperly set the amount of glue, ratio measurement error. 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 of the main agent do not react. High-purity ethyl acetate should be used.

3, the print surface has sprayed powder. Wipe gently with a dry cloth.

4, the print ink layer is too thick. Adhesive coating arrangements should be added to increase the pressure.

5, printing ink layer is not dry or not completely dry. Should be hot-pressed again and then gluing; choose a high solid content of the adhesive; increase the adhesive coating thickness; increase the drying temperature and so on.

6, the adhesive is absorbed by printing ink and paper, so that the amount of coating is insufficient. Should be re-formulated and set the amount of coating.

7, plastic film surface treatment is not enough or beyond the application period, so that the treatment surface failure. Plastic film should be replaced.

8, the pressure is too small, the speed is faster, the temperature is low. The film temperature and pressure should be increased and the vehicle speed should be appropriately reduced.