Materials used in the blowing film process are divided into two major categories: polymers and additives. Many types of polymers are used to produce blow-drying films, but most of them are different grades of polyethylene. Additives are often used to improve performance, appearance and economic benefits. The choice of raw material to produce a particular product is based on the product used. To produce any product with the desired characteristics, the best materials must be selected. The most important properties of the final product such as physical, mechanical, optical, thermal and electrical properties determine its quality. In addition to the properties of the final product, production conditions are also important in the choice of materials. Features such as good thermal stability, high melt strength, allowable pressure and no melt fracture (a film with no defect surface) define an optimal production process. And finally, the lowest cost is a key feature. Blown film has countless uses, but a large percentage of it is used for consumer goods, such as packaging and plastic bags. These products require a combination of performance, processing and price to provide polyethylene as an ideal polymer for most applications. Polyethylene is lightweight, water resistant, has a good balance between tensile and flexibility, and almost good transparency. Extrusion of polyethylene is easy and has high sewing capability, and perhaps the most important feature is its cheapness. In addition to the general properties of polyethylene mentioned, polyethylene is a scientifically well-known polymer that provides the design and control of a variety of polymerization techniques to achieve specific values for specific product characteristics. In this way, different types of polyethylene can be produced that are much stronger than usual, clearer and more flexible, and.. In the large family of polyethylenes, there are several types of polyethylenes for the production of blow-drying films. Of course, other polymers such as EVA and polypropylene are also used. A small number of polymers are used in certain monolayer films, which are often used as part of multilayer films. In the production of multilayer films, multiple extruders are connected to a die and streams of different feeds are combined into one layer of multilayer film. In the following sections, the types of polymers used in blow film extrusion are described in detail.
