Comparison of process principles: Film casting is a non-stretched, non-oriented flat extrusion film produced by melt drool quenching. There is no obvious orientation structure.
Extrusion method for film formation, common unidirectional stretching and biaxial stretching, of which biaxial stretching is a production method that has attracted much attention in recent years. The basic principle of biaxial stretching technology is that polymer raw materials are first heated and melted into thick pieces through an extruder, and then within a suitable temperature range above the glass transition temperature and below the melting point, the stretcher is used to perform a certain lengthwise and transverse directions Stretching by multiples makes the molecular chains oriented and ordered in a plane parallel to the film, and then heat-sets under tension to fix the oriented macromolecular structure. Finally, it is cooled and subsequently processed into a film.
Film formation by blow molding is usually manufactured by extrusion blow molding. The material is plasticized and extruded to form a tube blank for inflation molding, and then cooled, drawn and coiled. The blown film is oriented.
The difference in the molding methods from the above three processes results in a significant difference in the electrical conductivity of the film; at the same time, the stretched film has improved barrier properties compared to unstretched films, reduced permeability to gases and other gases, and improved optical properties, transparency and surface gloss Dimensional temperature and good thickness uniformity.
Comparison of application fields: Take PE protective film, PVC protective film and ordinary PP film as examples for comparison
PE protective film: The product has the characteristics of transparency, softness, good barrier and mechanical adaptability, high temperature cooking resistance (cooking temperature above 120 ℃), low temperature heat sealing (heat sealing temperature less than 125 ℃), etc. Mainly used as industrial protection, acrylic panel, glass panel and other inner packaging substrates, which can protect product life and increase aesthetics. It can also be used as the surface layer and compartment of stationery products, and can also be used as auxiliary film, such as photos and leaflets and labels of collectibles.
PVC protective film: has excellent printing properties, can be compounded with paper, PET and other substrates, has high definition and gloss, excellent ink absorption and coating adhesion, high tensile strength, excellent grease barrier properties , Low static characteristics, etc. It is widely used in the field of printing and compounding, and also used as packaging material in tobacco and other aspects.
Common PP protective film: Due to the simple process and low cost, the optical performance is slightly lower than CPP and BOPP. Mainly used in the outer packaging of snacks, bread, textiles, folders, record covers, sports shoes, etc.
Among them, the protective properties of PE protective film and PVC protective film are improved, and the application is wider. After compounding, it has moisture resistance, transparency, and stiffness. It has a wide range of applications and has obvious advantages in the industry. It is currently used in many applications.https://www.pe-protectionfilm.com/