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. When these factors are dealt with, you will have a variety of film quality problems.

1. There are snowflakes on the product

The cause of this failure is the following:

(1) Excessive dusting of printed matter: The printed matter is excessively dusted and cannot be completely dissolved by the adhesive. A large area of ​​snow spots will appear on the coated product. In this case, the amount of glue should be increased appropriately, or the powder on the printed matter should be removed before the film is covered.

(2) The amount of glue is too small: the amount of glue is too small and snow spots will appear on the entire surface of the printed matter. The solution is to increase the amount of glue properly.

(3) The pressure of the pressure roller is not suitable: If the pressure of the pressure roller is too high, the adhesive on the edge of the print will be squeezed out, leading to snow spots on the edge of the printed matter; The solution is to properly adjust the pressure of the pressure roller.

(4) There is dry rubber on the rubber roller: The glue on the rubber roller has a small amount of glue, which will cause the film product to appear snow spots. The solution is to wipe off the adhesive roller.

(5) Adhesive ring on the pressure roller: The adhesive extruded from the edge of the print or the adhesive extruded from the film hole sticks on the pressure roller. After a long time, it will form a dry apron. When the back prints are recoated, tiny snowflakes will appear. The solution is to wipe the pressure roller in time.

(6) Impurities in the adhesive: If there is too much dust in the surrounding environment, or there is dry rubber in the adhesive and cut film pieces, there will be snow spots on the film products. and so. Special attention should be paid to environmental sanitation; adhesives should be used up to be sealed in plastic tanks, or filtered before gluing.

2. Product has bubbles

(1) The printing ink layer is not dried: first hot pressing and then gluing, you can also postpone the date of the film to make it completely dry.

(2) The printing ink layer is too thick: The coating amount of the adhesive can be appropriately increased to increase the pressure and the composite temperature.

(3) The surface temperature of the composite roll is too high: Take measures such as air cooling, closing the heating wire, etc. to reduce the temperature of the composite roll as soon as possible

(4) Overheating temperature of the coating film: If the drying temperature is too high, it will cause crusting on the surface of the adhesive and foaming failure will occur. In this case, the drying temperature should be appropriately reduced.

(5) Film Cause: Foaming failure caused by wrinkling or loosening of the film, uneven film, or curling can be resolved by adjusting the tension or replacing the film.

(6) Binder Concentration Reasons: High binder concentration, high viscosity, or uneven coating and low dosage are also one of the reasons. In this case, thinner should be used to reduce the binder concentration, or the coating amount should be increased appropriately. And evenness.

(7) The pressure of the pressure roller is too small: The entire surface of the printed product has bubbles because the pressure of the pressure roller is too small, and the pressure of the pressure roller can be appropriately increased.

(8) Top paper: There is a bubble at the overlap of the two papers because the two front and back papers are topped together. This phenomenon is mainly manifested in the thick paper coating. If the printed matter is large, adjust the CVT handwheel counterclockwise so that the two papers have a certain amount of laps. When printing the mouthwash, the front and rear two sheets of paper can be properly pulled apart, but pay attention that the distance should not be extended. Too big. otherwise. After the film product is cut, the tail film will appear.

(9) Printed Flecks: The storage of printed materials is generally tens of thousands of sheets stacked together, which causes the moisture absorption of the entire area of ​​the paper not to be well-balanced, and the moisture absorption in the edge areas is more severe. This is the production of lotus leaves. The reason for the side. Prints with ruffles flatten out under the pressure exerted by the coating, but they will return to their original shape after leaving the pressure roller. This creates bubbles. The solution is: moisten the printed matter with flounces or spread out to dry.

3. Film products appear wrinkled

The main reasons for the wrinkling of the film products are uneven film transfer rolls, inconsistent or wavy edges at the ends of the film, excessive thickness of the adhesive layer, or unevenness between the ends of the electric roller and the rubber roller, inconsistent pressures, and unequal line speeds. This can be taken to adjust the transfer roller to the equilibrium state, more thin film, adjust the amount of glue and increase the temperature of the drying path, adjust the position of the electric roller and the rubber roller, and process parameters.

4. Bonding is not true
This phenomenon mainly occurs in thick paper films. The thick paper will have a certain degree of curling when it is rewinded, and the smaller the diameter of the rewinding, the more obvious. The film products that have not been dried immediately after the pressure roller has been applied tend to open at the edge of the paper that is curled, causing the adhesiveness to be impractical. In order to improve the film yield, the width of the laps should be reduced as much as possible to ensure that the width of the false bond is within the range of die-cut rinsing.

5. Film products made Alice.

The main causes of this failure are:

(1) Prints are too thin: Try to avoid laminating thin paper.

(2) Unbalanced tension: adjust the tension of the film to make it balanced

(3) Excessive compound pressure: Properly reduce the compound pressure.

(4) Temperature is too high: Reduce the compound temperature.

(5) The film tension is too large: if the film tension is too large, the film will be stretched and deformed. After the product is cut and removed, the film will return to its original shape, causing the product to curl to the film side. The solution is to adjust the screw depth of the film expansion screw and reduce the braking force.

(6) The winding tension is too large: if the winding tension is too large, the film and the printed product will be deformed at the same time, but the 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 friction force of the winding power wheel.

(7) Humidity in the environment: When the film-covered product with high moisture content is fully dried, the paper will be deformed by dehydration, causing the finished product to curl to one side of the paper. The solution is to control the humidity in the workshop.

(8) Short drying time: Short drying time. If the film product is not fully dried, it will curl. The solution is to extend the drying time.

6. The product is not sticky

The main causes of this failure are:

(1) Improper selection of adhesives, improper setting of the amount of glue, miscalculation of proportioning: reselection of adhesive brand number and coating amount, and accurate ratio

(2) Poor surface condition of the printed matter: If the powder is sprayed, the ink layer is too thick, or the ink is not dry or has not been thoroughly dried, the dust may be wiped off with a dry cloth, or the adhesive coating may be increased. Quantity, increase the pressure, and use light and pressure to re-glue again, 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.

(3) Adhesive is absorbed by the ink and paper, resulting in insufficient coating amount: consider re-setting the formula and coating amount.

(4) The amount of glue is too little: the amount of glue is small, the solid content is also small, and the adhesion force is necessarily insufficient. The solution is to increase the amount of glue.

(5) Printed area of ​​the printed matter is large: Due to the smooth surface of the ink, the adhesive is difficult to wet. diffusion. Infiltration, and thus not sticky. The solution is: increase the solid content of the adhesive and the thickness of the adhesive layer. Increase the outside temperature of the film.

(6) Deterioration of glue: Check the date of manufacture and shelf life of the glue before use.

(7) Thin film exceeds shelf life

7. Bad coating.

The uneven thickness of the plastic film, the compound pressure is too small, the film is slack, and some of the adhesive curing rollers in the rubber tank swell or deform may cause uneven coating; after a failure occurs, the causes should be found as soon as possible and corresponding measures must be taken. Adjust traction, increase compound pressure, or replace film, rollers, or adhesives.

8. Product turns black

This mainly occurs on large areas of gold and bronzing products. This is due to chemical reactions between the chemically active elements of the binder and the gold powder. The solution is to use special gold ink or special adhesives, or it can be gilded after laminating.