Discussion on the process of casting PET film-film supplier

by:POLYVA     2022-01-30
The PET cast film production line uses polyethylene terephthalate PET as the raw material to produce environmentally friendly polyester film (CPET) with a casting process. The OPET film is processed and produced by a casting unidirectional stretching method. Some areas can replace PVC film, BOPET film, BOPP film, etc. for packaging, which can greatly reduce equipment input costs and film production costs. 1. Requirements for the moisture content of raw materials-it is an indicator that directly affects the drying effect. If the content exceeds 0.5%, it will affect the moisture content of the circulating hot air of the pre-crystallizer, and will not dry the surface moisture of the slices in a short time. It is easy to agglomerate when entering the drying tower at high temperature, and the agglomeration directly affects the drying effect, and it is also easy to block the discharge port, which makes the extruder poorly fed, causing fluctuations in the extrusion pressure and die pressure, resulting in film thickness Unevenness, causing membrane rupture. If a twin screw is used, it has a double vacuum exhaust function, which can avoid drying, which is more conducive to the processing characteristics of PET. 2. In order to improve the cooling effect, positive and negative pressure air knives are set before and after the die. The positive pressure air knife blows the compressed air to the film surface, while the negative pressure air box draws the air between the film and the casting roll to make the film close to the roll surface. If the electrostatic suction method is used, the effect will be better. The PET film is formed by the casting method, but the PET melt index is very large, and it flows down like water, or one by one, which is difficult to form a film. Add fillers, plasticizers, heat stabilizers and other PET additives, etc. The main working principle is: after drying the high molecular polymer materials, weigh them according to the proportion, mix them, suck them into the hopper, and enter the barrel screw. The screw in the barrel rotates to transport the material forward. Due to the use of electric heating outside the barrel, the temperature rise of the material needs to be accurately controlled. The screw in the barrel rotates internally to cause the material to generate shear and frictional heat in the barrel. Gradually plasticized and melted, uniformly extruded from the die mouth through the filter and distributor, forming a sheet-like melting, through the filter and distributor, evenly extruded from the die mouth, and the molded sheet melt is cast to a smoothly rotating forehead roller Above, in order to improve the cooling effect, if the electrostatic suction is used, the effect will be better. It is often used to set up the negative pressure air knife before and after the die. The positive pressure air knife blows the compressed air to the film surface, while the negative pressure air box draws the air between the film and the casting roll, so that the film is tightly attached to the roll surface, and is cooled and formed on the casting roll and cooling roll. Multi-stage traction, film thickness gauge, corona processor, swing mechanism, edge trimming, (after eliminating static electricity) winding into film products. It is a company specializing in the production of PET film with multiple functions, such as: transparent PET film, milky white PET film, release PET film, supply of PET motor film, etc. With a wide variety of products, affordable prices, and environmental protection, we provide customers with excellent quality and service based on the service tenet of excellence in production, honesty and trustworthiness in distribution, and warm and thoughtful service, and the spirit of assisting partners to achieve their own careers. Interested parties welcome to inquire!
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