Some common technical problems in flexible packaging production

Changes in the production environment will more or less cause fluctuations in the quality of flexible packaging production, and even in the case of unqualified products. Now it has entered the winter season. It is the most concerned issue for soft packaging enterprises to understand the impact of low temperature environment on flexible packaging production and how to prevent precautions in advance and reduce unnecessary quality losses.

Effect on wetting properties of raw and auxiliary materials

Prior to official printing , the plastic film is typically corona treated to meet the printing process requirements. In the case of low temperatures in winter, the wettability of many films will be worse and harder. This will increase the surface tension of the film. In addition, the fluidity and dispersibility of the ink will deteriorate when the temperature is low. , resulting in an increase in ink viscosity and a decrease in coloration rate.

If the flexible packaging company is not aware of the above problems, improper storage and storage of the film and ink after entering the winter will have a certain impact on the printing and compounding of the film. For example, when printing, there will be quality problems such as uneven coloring of the shallow screen plate and poor firmness of the actual map text; when the composite is used, unevenness in the glue, poor composite strength, and the high-temperature cooking bag may be broken.

Precautionary measures: The temperature of the raw and auxiliary material storage warehouse should be kept at around 20 °C.

Solvent residue exceeded

At different temperatures, the latent heat of vaporization of the solvent is different. The lower the temperature, the harder it is to evaporate. Therefore, in winter, the residual amount of solvent in the printing process will be relatively high.

Precautions: During the printing process, the machine speed should be properly controlled to increase the drying temperature to promote the evaporation of the solvent and reduce its residual amount in the film.

Effect on initial adhesion at the time of compounding

In the high-temperature environment in summer, the PE composite film of the dry composite compact machine is peeled off, and the adhesive film is adhered to both sides of the composite film, which is manifested as cohesive failure of the adhesive layer. In the low temperature environment in winter, the PE composite film of the dry composite just-off machine is often peeled off from the interface between the adhesive layer and the PE film when peeling off, and the adhesion is small, indicating that the adhesive has not yet been able to Completely wet the surface of the PE film. Sometimes the composite film roll taken out from the curing chamber has a large number of bubbles in the outer layer for a dozen or so circles. In serious cases, a "tunnel" phenomenon may occur. The root cause is that the low temperature causes the initial adhesive force of the adhesive to decrease.

Precautionary measures: 1 Preheat the PE film when unwinding; 2 Note that the storage environment temperature of the raw and auxiliary materials should not be too low.