Detailed classification and introduction of plastic films
Detailed classification and introduction of plastic films
1. PVA-coated high-barrier film PVA-coated high-barrier film is made by coating PVA with nano-inorganic substances on polyethylene film and then printing and compounding the plastic film cost-effectively. On the premise of not greatly increasing the cost, It solves the technical bottleneck of poor barrier performance of the current three-layer polyethylene co-extrusion packaging film. In the past two years, some domestic dairy processing enterprises have used the high-barrier film produced by the company for the milk film used in aseptic packaging, and the oxygen barrier rate is less than 2cm3/(m2·24h·0.1MPa). Its barrier performance is not only significantly better than EVOH five-layer co-extruded film, but also the packaging cost is greatly reduced, which not only ensures all the quality requirements of aseptic packaging for the packaged objects, but also greatly reduces the aseptic packaging requirements of food processing enterprises. It solves the technical bottleneck of poor barrier performance of the current three-layer polyethylene co-extrusion packaging film, and can be used for packaging beverages, juices, milk, soy sauce vinegar, etc. 2. Biaxially oriented polypropylene film (BOPP) Biaxially oriented polypropylene film is obtained by co-extruding polypropylene particles into a sheet, and then stretching in both vertical and horizontal directions. Due to the orientation of the stretched molecules, this film has good physical stability, mechanical strength, air tightness, high transparency and gloss, toughness and wear resistance, and is the most widely used printing film at present. 40 μm, the most widely used is 20 μm. The main disadvantage of biaxially oriented polypropylene film is poor heat sealing, so it is generally used as the outer film of the composite film. Serving dry food. Because the surface of the biaxially oriented polypropylene film is non-polar, high in crystallinity and low in surface free energy, its printing performance is poor, and the adhesion to ink and adhesives is poor. deal with. 3. Low-density polyethylene film (LDPE) Low-density polyethylene film is generally made by two processes: blow molding and casting. The thickness of cast polyethylene film is uniform, but due to its high price, it is rarely used at present. Blown polyethylene film is made by blowing grade PE particles through blow molding machine, and the cost is low, so it is the most widely used. Low-density polyethylene film is a translucent, glossy, soft-textured film with excellent chemical stability, heat-sealability, water resistance and moisture resistance, freezing resistance, and can be boiled. Its main disadvantage is that it has poor barrier properties to oxygen. It is often used in the inner film of composite flexible packaging materials, and it is also the most widely used and most used plastic packaging film, accounting for more than 40% of the consumption of plastic packaging films. . Because polyethylene molecules do not contain polar groups, and have high crystallinity and low surface free energy, the film has poor printing performance and poor adhesion to inks and adhesives. Surface treatment. Polyester film (PET) Polyester film is made of polyethylene terephthalate as raw material, made into thick sheet by extrusion method, and then made of biaxially stretched film material. It is a colorless, transparent and glossy film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high temperature and low temperature resistance, chemical resistance, oil resistance, air tightness and fragrance retention Good, it is one of the commonly used barrier composite film substrates. However, the price of polyester film is relatively high, and the general thickness is 12 μm. 4. Nylon film (PA) Nylon film is a very tough film with good transparency, good gloss, high tensile strength and tensile strength, and good heat resistance, cold resistance and oil resistance. It is relatively soft and has excellent oxygen barrier properties, but has poor water vapor barrier properties, high moisture absorption and moisture permeability, and poor heat sealing properties. It is suitable for packaging hard items, such as greasy food, meat products, fried food, vacuum-packed food, retort food, etc. 5. Cast polypropylene film (CPP) Cast polypropylene film is a polypropylene film produced by the casting process, and can be divided into ordinary CPP and cooking grade CPP, with excellent transparency, uniform thickness, and vertical and horizontal The performance is uniform, and it is generally used as the inner layer material of the composite film. The thickness of ordinary CPP film is generally between 25 and 50 μm. After compounding with OPP, the transparency is good, the surface is bright, and the hand feel is firm. This material is used in general gift packaging bags. This film also has good heat sealability. The thickness of the cooking grade CPP film is generally between 60 and 80 μm, and it can withstand high temperature cooking at 121 ° C and 30 min, with good oil resistance, air tightness, and high heat sealing strength. Retort grade CPP film is used. 6. Aluminized film The most widely used aluminized films are polyester aluminized film (VMPET) and CPP aluminized film (VMCPP). Aluminized film has the characteristics of plastic film,It also has the properties of metal. The function of aluminum plating on the surface of the film is to block light and prevent ultraviolet radiation, which not only prolongs the shelf life of the contents, but also improves the brightness of the film. It replaces aluminum foil to a certain extent. , Aluminized film is widely used in composite packaging. Currently, it is mainly used in the packaging of dry and puffed food such as biscuits, as well as the outer packaging of some medicines and cosmetics.