How to improve the printability of PVC calendered film

Methods to improve the printing adhesion of PVC calendered film:

1. Quality control of the base film

The performance of the base film is related to whether the printing film has adhesion. Direct relationship, therefore, it is very important to strictly control the quality of PVC calendered film. If the film is found to be soft, attention should be paid to controlling the amount and type of plasticizer in the base film, and the amount of lubricant should not be too much. At the same time, observe whether the temperature of the calendering roller is too high; if the base film is tight and has a big belly, it is often due to the thin film. Caused by uneven shrinkage, first check whether the film has "three highs and two bottoms", whether the roller temperature is uniform, and whether the axis cross angle is too large; secondly, check whether the cooling is uniform, whether the coiling tension is appropriate and stable, and whether the rolling speed ratio Whether it is reasonable, etc. And the bottom film should be cold cut as much as possible. Only by reasonably determining the calendering film formula and calendering process conditions can the quality and performance of the base film be stable, which will bring convenience to the subsequent printing process, ensure printing quality, and avoid sticking.

2. Reasonably determine the composition and formula of the ink

PVC printing ink is made of transparent original pulp and color paste mixed in a certain proportion. When used, it is diluted with a mixed solvent to the desired required viscosity. The amount and type of plasticizers and solvents used in the ink composition have an important impact on the adhesion phenomenon of the printing film. Generally, the impact of the selected materials on factors such as the solubility of chlorine-vinegar resin, the wetting and penetrating ability of the base film, the viscosity adjustment ability, and the drying speed should be comprehensively considered. It is usually better to choose DBP as plasticizer. DBP has high plasticizing efficiency, strong volatility, and is easy to dry; the solvents are generally cyclohexanone, butyl acetate, acetone, and ethyl acetate, and are often used as mixed solvents.

From the actual production point of view, the preparation of PVC calendered film printing ink is shown in Table 1. It is worth noting that the ratios in the table should be revised according to the climate and specific production conditions. For example, in summer, when the temperature is high and the solvation ability is strong, the amount of cyclohexanone in the original pulp can be appropriately reduced; in winter, when the temperature is low and the solvation effect is weakened, the amount of cyclohexanone can be appropriately increased, and at this time, the amount of acetone in the mixed solvent can be increased. , and use ethyl acetate to replace part of butyl acetate to speed up the evaporation of the solvent and avoid adhesion of the printed film.

3. Improve the fineness of the color paste and the uniformity of solid-liquid phase dispersion

The fineness of the ink has a very important impact on printing adhesion, and the fineness of the ink depends on the quality of the color paste. Fineness. In the process of color matching paste, each component must be fully mixed and evenly ground to a certain fineness with a colloid mill. Usually, the color paste particles are controlled below 30 μm.

During the grinding process, attention should be paid to: ① The colloid mill must be cooled by water; ② The flow rate of circulation pumps I and II should be adjusted consistent with the colloid mill fineness; ③ The colloid grinding fineness can be adjusted according to production needs and raw materials. Adjustments are made for different varieties. A can of color paste needs to be colloid milled three times (i.e. coarse, medium and fine) before it can be used for production.

By grinding the color paste in this way, the fineness and degree of dispersion are greatly improved, and the proportion of pigments in the color paste can be reduced. This not only reduces the cost, but also improves the fluidity of the color paste, makes it easy to produce, and avoids bandages. Paste, paste version. At the same time, the engraving depth of the printing plate roller can be reduced, the screen line can be increased, and the pulp consumption per ton of film can be reduced. In this way, the tinting strength and color fastness of the product are improved, the ink is full, the color is delicate and bright, it is easy to dry and the phenomenon of being sticky and unable to be opened after being rolled is completely avoided, which greatly improves the quality of PVC printing film.