Failure and Exclusion in Lamination Process

Due to factors such as material, process, equipment, and environment, the film of the printed product will appear blisters, wrinkles, ink retreating, and film stripping. Let's talk about how to avoid these phenomena.

First, several causes of failure:

1. There is a problem with the printed material itself

If paper with poor uniformity is used for printing, the amount and speed of ink absorption on the paper will be inconsistent, resulting in quantitative changes in the tightness, evenness, smoothness, and moisture of the paper. If the ink is mixed too thick and the ink layer is too thick, the wetting, diffusion, and penetration of the adhesive are poor, the molecular motion is less active, and the mechanical bonding force is small. In addition, in printing, in order to avoid printing plate stencils, drying oil is often added to the ink so that the ink layer is quickly congealed and the surface of the ink layer is crystallized. The surface of the ink is smooth and tough, and the adhesive force is lost, and the adhesive cannot be bonded thereto. Wetting and affinity, seriously affect the adhesion fastness, resulting in failure of the coating.

2. Effect of Operation Process and Printing Environment on Film Quality

When laminating the printed matter, first apply a layer of adhesive on the surface of the plastic film. Although the adhesive has not yet reached the laminating requirement even though it has been dried, the solvent should be added to dilute the adhesive for quick drying. If the moisture content is too high, air bubbles are likely to appear when the film is pressurized, resulting in peeling and peeling. At the same time, if the film shop does not control the temperature, air flow, and humidity, the film can easily absorb substances such as grease, moisture, and dust in the air, thereby lowering its surface energy. Excessive humidity can also affect the volatilization of the solvent in the adhesive. Too much residual solvent will create air separation in the film, making it impossible to stick the film. Roller pressure is not uniform, the rubber roller itself does not dry, there is dirt on the roller, and wrinkling of the film is also caused.

Second, there is poor adhesion and troubleshooting

1. Inadequate selection of adhesives, improper setting of the amount of glue, and incorrect measurement of the proportions, all types and amounts of adhesives 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. The surface of the print is dusted. Wipe gently with a dry cloth.
4. The print ink layer is too thick. Should increase the amount of adhesive coating, increase the pressure.
5. The printed ink is not dry or dry. Should be hot-pressed again and then glue; select high solid content adhesive; increase the coating thickness; increase the temperature of the drying tunnel.
6. When the adhesive is absorbed by printing ink and paper, the coating amount is insufficient. Should be re-formulated and set the amount of coating.
7. Plastic film surface treatment is not enough or exceeds the pot life, so that the processing surface failure, plastic film should be updated.
8. The pressure is small, the speed is faster and the temperature is lower. The film temperature and pressure should be increased and the vehicle speed should be appropriately reduced.

Third, the phenomenon of blistering, generally belongs to the following conditions:

1. Printing ink is dry. Should be hot-pressed again and then glue, postponed coating time, to completely dry.
2. The printing ink layer is too thick. The amount of adhesive applied should be increased to increase the pressure and the composite temperature.
3. The drying temperature is too high and the adhesive surface is crusted. Drying temperature should be reduced.
4. The surface temperature of the composite roller is too high. The composite roll temperature should be reduced.
5. The film has wrinkles or looseness, and the film is uneven or curled. Replace the film and adjust the tension.
6. Thin surface dust and impurities. Should be promptly removed.
7. The adhesive is unevenly coated and used in small amounts. Should increase the amount of coating and uniformity.
8. The binder concentration is too high, the viscosity is large, and the amount of coating is not uniform. Diluents should be added to lower the binder concentration.

Fourth, film wrinkling

1. The film transfer roller is not balanced. The transfer roller should be adjusted.
2. Loosely inconsistent or wavy sides of the film. Replace qualified film.
3. The glue layer is too thick and the solvent evaporation is not thorough, which affects the viscosity. It is squeezed by the pressure roller and slips between the paper and the film. The amount of glue should be adjusted to increase the temperature of the drying tunnel.
4. The electric 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 that are often encountered in the packaging film coating are generally included in these categories. Lamination is an important post-printing process. Packaging printing is a comprehensive issue.