Affected by the performance of PVC film, it is necessary to pay attention to the influence of many factors in processing. PVC printing, ink selection, bag making, bonding, use, etc. are all subject to certain restrictions. This article will introduce them in detail.
1. Printing of PVC film
Because the printing ink of offset printing cannot be compatible with PVC film, 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, so the drying temperature of the drying box during printing cannot be higher than 60℃, 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.
2. Printing ink for PVC film
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 properties as the printed PVC film, and only then will there be affinity and a good combination. PVC film will swell and dissolve in grease, ketones, aromatic hydrocarbons and halogenated hydrocarbon solvents, so composite inks containing oxidized polypropylene with 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 PVC ink, 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 become rough or wrinkle.
3. Bag making of PVC film
Can not use direct heat type and pulse type sealing machine to heat seal. If the bag is directly heated to make the bag, the film surface of the bag will shrink and wrinkle, and the sealing will be poor. High-frequency or ultrasonic heat sealing and cutting machines can be used for heat sealing.
4. Bonding of PVC shrink film
Many plastic bottles for beverages, fruit juices, and mineral waters are glued on the shrink bottle label interface, usually with perchlorovinyl resin glue. The glue is 40%~45% perchloroethylene resin and 55%~ It is made by melting 60% cyclohexanone solvent. But the amount of glue cannot be too large, otherwise the solvent of the glue will dissolve the film and cause adhesion.
5. Uses of PVC shrink film
The PVC film added with plasticizers dioctyl formate, dibutyl formate, or dioctyl diacid, and dibutyl diacid has many advantages such as softness, large stretch, high strength, impact resistance, and aging resistance, but It has a big smell and cannot be used as packaging for direct contact with food.