Questions about PVC film

1. Calendering is through the gap of two or more oppositely rotating rollers. With the help of the shearing force between the rollers, the material is squeezed many times, so that the material can be fully mixed, and on the basis of further plasticization. Spread into a continuous film (sheet) product of a specified size. Calendering is the main forming method for soft PVC. For soft PVC products, the tail film with a thickness of less than 0.25mm, and the film with a thickness of 0.25~1mm are thin.

2. Blow molding is an important production method for general packaging films. It started to produce soft PVC film early, and later developed PVC film for rigid food packaging. The general shrink film is also produced by this method and then biaxially stretched.

The flat film method is also one of the methods to produce cast film and stretch film (self-mucosal film). Since the price of the equipment is higher than that of ordinary film blowing equipment, it is used less. In addition, according to its special purpose, it adopts special formula and technology to produce, such as uniaxially stretched film, medical film, cold-resistant film and other manufacturing methods. Polyvinyl chloride composite films manufactured by the composite method are relatively less than polyethylene and polypropylene composite films.

3. Soft and hard PVC films have slightly different performances, but they all have one thing in common, that is, they have good transparency and printing adaptability. They also have a common shortcoming, which is heat resistance and poor cold resistance.

For rigid PVC film, taking advantage of its transparency, ease of processing, and low price, it can be used as a protective container for packaging fruits, a protective container for eggs, a tray for confectionery, etc., and as a film forming container. For soft PVC film, make use of its flexibility, processing type, in the medical field, make catheters, infusion bags, etc. Utilizing the self-adhesive properties of stretched film, it is used for packaging of fruits, meats, and fish. Among the rigid PVC films, heat-shrinkable PVC films that have a heat-shrinkable type due to stretching, shrink labels for glass bottles or plastic bottles and shrink films for the outer layer of bottle caps, bulk packaging and dry battery shrink packaging materials Aspects of the purpose. With its large shrinkage rate, even and beautiful shrinkage effects can be obtained for the bottleneck parts with diameter differences. The cylinder shrink label used for chemicals such as bleach, that is, to take advantage of its chemical resistance.