Some Problems Occurring in Lamination and Solutions (2)

Fourth, common faults and solutions

There are many factors that affect the quality of the coating film. In addition to the objective factors such as paper, ink layer, film, and adhesives, subjective factors such as temperature, pressure velocity, and glue amount also influence. The poor handling of these factors will produce a variety of film quality problems.

1. Poor adhesion.

A. Due to the improper selection of adhesives, improper setting of the amount of glue, and misalignment of the coated film caused by incorrect ratio measurement, the adhesive brand number and coating amount should be re-evaluated, and the ratio should be accurately determined;

B. If the print surface is in poor condition, such as dusting, ink layer is too thick, the ink is not dry or not completely dry, etc., resulting in poor adhesion, you can use a dry cloth to gently wipe off the powder, or increase the adhesive coating. Volume, increase the pressure, and use the first hot-press again and then glue, or change to a high solid content adhesive, or increase the adhesive coating thickness, or increase the temperature of the drying path and other methods to solve;

C. If the amount of coating is insufficient due to the adhesive being absorbed by printing ink and paper, consider re-setting the formula and amount of coating.

D. Check whether the film corona treatment reaches 36-40 dyne.

E. Bonding at the edge is not true. This is mainly manifested in thick paper. The paper will curl when it is rewinded. And the smaller the diameter of the winding, the more obvious. A film product that has not been dried immediately after the pressure roller has been applied is often topped off by the curled paper at the edge of the edge, resulting in a false bond. In order to increase the yield, the width of the laps should be reduced as much as possible to ensure that the width of the adhesive is not within the die-cutting mouth.

2. Foaming.

A. The reason for this is that if the printing ink layer is not dried, it should be hot-pressed again and then glued, or the film can be postponed and dried completely;

B. Pressurizing roller pressure is too small The entire print surface has bubbles because the pressure is too small and the pressure of the pressing roller can be increased. If the printing ink layer is too thick, the coating amount of the adhesive may be appropriately increased to increase the pressure and the composite temperature;

C. If the surface temperature of the composite roll is too high, cooling measures such as air cooling and closing of the heating wire should be taken to reduce the temperature of the composite roll as soon as possible;

D. If the film drying temperature is too high, it will cause clogging on the surface of the adhesive and foaming failure. In this case, the drying temperature should be properly reduced.

E. Foaming failures caused by wrinkles or loosening of the film, uneven film, or curling, can be resolved by adjusting the tension or changing the film.

F. High concentration of binder, high viscosity, or uneven coating and low dosage is also one of the reasons. In this case, thinner should be used to reduce the binder concentration, or the coating amount and uniformity should be appropriately increased.

G. There is a bubble at the overlap of the two papers because the top and back of the paper are together. This is mainly manifested in thick paper. If the print bite is large, the two sheets of paper may have a certain amount of overlap by adjusting the equipment; when the mouth is small, two sheets of paper may be properly pulled apart, but the tail film may appear after the slitting. Therefore, the distance should not be too large.

H. Printed materials are generally stored in tens of thousands. This causes the moisture absorption of the paper to not be balanced over the entire area, and the edge area is faster, which is why the flounces occur. Foiled prints will flatten under the pressure of the lamination, and will return to their original shape after the pressure roller is applied. This creates bubbles. The solution is to humidify or spread dry the printed leaflet.

3. uneven coating.

A. uneven plastic film thickness, composite pressure is too small, the film is slack, a part of the glue tank adhesive curing, roller swelling or deformation will cause uneven coating;

B. After a failure occurs, the cause should be identified and appropriate measures must be taken as soon as possible, either by adjusting the traction, increasing the compound pressure, or replacing the film, roller, or adhesive.

4. Wrinkled film.

The reasons for this are generally unbalanced film transfer rollers, inconsistent or wavy edges at the ends of the film, excessive thickness of the adhesive layer, or unevenness between the roller and the rubber roller, uneven pressure, and unequal line speeds. Roll to the equilibrium state, replace the film, adjust the amount of glue and increase the temperature of the drying path, adjust the position and process parameters of the electric roller and the rubber roller, and other measures.

5. Film products hair Qiao.

A. The reason is that the printed matter is too thin, the tension is unbalanced, the film is pulled too tight, the compound pressure is too large or the temperature is too high;

B. The corresponding treatment is to avoid thin film processing;

C. Adjust the tension of the film to make it balanced; properly reduce the composite pressure and lower the compounding temperature.

6. The product has snow spots.

A. If the print dusting is too large, it can not be completely dissolved by the glue, there will not be a large area of ​​snow. In this case, the amount of glue should be increased or cleaned before the film is sprayed.

B. When the amount of glue is too small, snowflakes will appear on the entire surface of the printed matter. The solution is to increase the amount of glue.

C. Pressing the roller too much pressure will squeeze the glue at the edge of the print, resulting in snowflake on the edge of the print; The solution is to adjust the pressure roller pressure.

D. The glue roller has a small amount of glue on the dry rubber, which will make the film product appear snow. The solution is to wipe the applicator roller clean.

E. Extruded glue on the edge of the printed matter or glue squeezed from the pinhole of the film sticks on the pressure roller. After a long time, a dry apron will form. When the back print is covered with film, tiny snowflakes will appear here. The solution is to wipe the pressure roller in time.

F. If there is too much dust in the surrounding environment or there is dry rubber and glued film fragments in the glue, the coated product will have snow, so we should pay attention to environmental sanitation, glue can not be used, it should be poured back to the plastic barrel and sealed. Or take the method of filtering before gluing.

7. The product curls after slitting.

A. Excessive tensile force of the film will cause it to undergo elongational deformation. After the product is slit and the external force is removed, the film will be restored to its original shape, causing the product to curl to one side of the film. The solution is to adjust the screwing depth of the film tensioning screw and reduce the braking force. .

B. Rolling too much tension will cause deformation of the film and print at the same time, but the amount of deformation is not the same. After the removal of the external force, the product will curl to the side of the paper, especially the thin paper. The solution is to reduce the frictional force of the winding power wheel (friction sprocket).

C. After the film product is fully dried, the paper will be deformed by dehydration and the finished product will be curled toward the side of the paper. The solution is to control the humidity in the workshop.

D. Short drying time

8. The product turns black.

This is mainly manifested in large-area gold printing and bronzing products. This is due to chemical reactions between the chemically active elements of the glue and the gold powder. The solution is to use special gold ink or special glue for the gold products, or to stamp gold after the foil stamping products.