Factors affecting the performance of PVC films
Because the printing ink of offset printing cannot be compatible with PVC films, and the printing plate of letterpress printing will be swelled and corroded by PVC ink, it is usually only possible to use two methods of gravure printing and screen printing for printing. Printed PVC film will be softened and deformed at 60~70℃, and the printing will not match the printing plate, let alone the overprinting accuracy. Therefore, the drying temperature of the drying box during printing cannot be higher than 60℃, and the general printing drying The temperature is preferably 20~30℃. If you use the gravure printing machine of the direct-heating drying box, the heating of the drying box cannot be turned on, just turn on the air blower.
The principle of printing ink for plastic film is what kind of plastic ink should be used for the plastic film, that is, the binder of the ink has the same performance as the printed PVC films, and only then will there be affinity and a good combination. PVC films will swell and dissolve in grease, ketones, aromatic hydrocarbons and halogenated hydrocarbon solvents, so composite inks of oxidized polypropylene containing a large amount of fats and ketones cannot be used. When using polyamide surface printing inks, beware of the precipitation of the softener in the PVC film, which will make the ink anti-sticky and cause film adhesion. In addition, when using special ink for PVC, pay attention to the amount of ink not too large, otherwise the PVC film will be swelled and melted by the cyclohexanone solvent in the ink, causing the surface of the film to be rough or wrinkled.
Can not use direct heating type and pulse type sealing machine to heat seal. If the bag is made by heating directly, the film surface of the bag will shrink and wrinkle, and the sealing will be poor. High-frequency or ultrasonic heat-sealing and heat-cutting machines can be used for heat-sealing processing.