Abstract: You will see various films in life, such as cling film, greenhouse film and chemical film, which are all a type of plastic film. In other words, there are too many kinds of plastic films, and each plastic film has many different uses. Do you know what types of plastic films there are? Is there any use for each? Now let’s learn about the classification of plastic films and their respective characteristics with the editor of Dishi.com. What are the types of plastic films? What are the characteristics of plastic films?
PVA-coated high-barrier film
PVA-coated high-barrier film is PVA coated with nano-inorganic substances added It is cost-effectively printed and compounded with polyethylene film by plastic film. Without significantly increasing the cost, it solves the technical bottleneck of the current poor barrier properties of three-layer polyethylene extruded packaging films. In 2008, after three years of hard work and independent innovation, the scientific researchers of Cangzhou Jinlong Plastic Co., Ltd. finally took the lead in bringing a nationally patented product, PVA-coated high-barrier milk film, to the market. In the past two years, the milk film used by some domestic dairy processing companies for aseptic packaging has adopted the high-barrier film produced by this company, and its oxygen barrier rate is less than 2cm3/(m2·24h·0.1MPa). Not only is its barrier performance significantly better than EVOH five-layer 100% extruded film, but the packaging cost is also significantly reduced. This not only ensures all the quality requirements for aseptic packaging of the packaged objects, but also greatly reduces the sterility requirements of food processing enterprises. The cost of packaging solves the current technical bottleneck of poor barrier properties of three-layer polyethylene extruded packaging films, and can be used to package beverages, juices, milk, soy sauce, vinegar, etc.
Biaxially oriented polypropylene film (BOPP)
Biaxially oriented polypropylene film is made of polypropylene particles that are extruded into sheets and then laminated in both vertical and horizontal directions. Made by stretching. Due to the orientation of the stretched molecules, this film has good physical stability, mechanical strength, air tightness, high transparency and gloss, and is tough and wear-resistant. It is currently the most widely used printing film, and is generally used with a thickness of 20~ 40μm, the most widely used is 20μm. The main disadvantage of biaxially oriented polypropylene film is poor heat sealability, so it is generally used as the outer film of composite films. For example, after compounding with polyethylene film, its moisture resistance, transparency, strength, stiffness and printability are all better, and it is suitable for Contains dry food. Since the surface of the biaxially oriented polypropylene film is non-polar, has high crystallinity and low surface free energy, its printing performance is poor and its adhesion to inks and adhesives is poor. Surface treatment is required before printing and lamination. deal with.
Low density polyethylene film (LDPE)
Low density polyethylene film is generally made by two processes: blow molding and casting. Cast polyethylene film has a uniform thickness, but is rarely used today due to its higher price. Blown polyethylene film is made of blow molding-grade PE particles blown by a blow molding machine. It has a low cost and is therefore the most widely used. Low-density polyethylene film is a translucent, glossy, soft film with excellent chemical stability, heat sealability, water resistance and moisture resistance. It is resistant to freezing and can be boiled. Its main disadvantage is that it has poor oxygen barrier properties. It is often used as the inner film of composite flexible packaging materials. It is also the most widely used and used plastic packaging film, accounting for more than 40% of plastic packaging film consumption. .
Since polyethylene molecules do not contain polar groups, have high crystallinity and low surface free energy, the film has poor printing performance and poor adhesion to inks and adhesives. Therefore, surface treatment is required before printing and lamination.
Polyester film (PET)
Polyester film is made of polyethylene terephthalate as raw material, made into thick sheets by extrusion method, and then biaxially stretched Made of film material. It is a colorless, transparent and shiny film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high and low temperature resistance, chemical resistance, oil resistance, air tightness and fragrance retention. It is one of the commonly used barrier composite film substrates. However, polyester film is more expensive and generally has a thickness of 12 μm. It is often used as the outer material for retort packaging and has good printability.
Nylon film (PA)
Nylon film is a very tough film with good transparency, good gloss, high tensile strength and tensile strength, and It has good heat resistance, cold resistance, oil resistance and organic solvent resistance, excellent wear resistance and puncture resistance, and is relatively soft. It has excellent oxygen barrier properties, but has poor barrier properties against water vapor and absorbs moisture. It has high moisture permeability and poor heat sealability, so it is suitable for packaging hard items, such as greasy food, meat products, fried food, vacuum packaged food, steamed food, etc.
Cast polypropylene film (CPP)
Cast polypropylene film is a polypropylene film produced by the casting process, and can be divided into two types: ordinary CPP and cooking grade CPP , has excellent transparency, uniform thickness, and uniform vertical and horizontal properties. It is generally used as the inner layer material of composite films. The thickness of ordinary CPP film is generally between 25 and 50 μm. After compounding with OPP, it has better transparency, bright surface and firm feel. This material is generally used in gift packaging bags. The film also has good heat sealability. The thickness of retort-grade CPP film is generally between 60 and 80 μm. It can withstand high-temperature cooking at 121°C for 30 minutes. It has good oil resistance and air tightness, and has high heat sealing strength. Generally, the inner layer of meat packaging is made of retort-grade CPP film. CPP film.
Aluminized film
At present, the most widely used aluminum films include polyester aluminum film (VMPET) and CPP aluminum film (VMCPP). Aluminized film has the characteristics of both plastic film and metal. The function of aluminum plating on the surface of the film is to block light and prevent ultraviolet radiation, which not only extends the shelf life of the contents, but also improves the brightness of the film. It replaces aluminum foil to a certain extent. It is also cheap, beautiful and has good barrier properties. Therefore , Aluminized film is widely used in composite packaging. It is currently mainly used in the packaging of dry and puffed foods such as biscuits and the outer packaging of some medicines and cosmetics.