Several plastic packaging films produced by the ho

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Several plastic packaging films produced by film blowing machines

Plastic packaging and plastic packaging products account for an increasing share in the market. Especially composite plastic flexible packaging has been widely used in food, medicine, chemical industry and other fields. Among them, food packaging accounts for the largest proportion, such as beverage packaging, quick-frozen food packaging, boiled food packaging, fast food packaging, etc, These products have brought great convenience to people's survival

several common films

1. Biaxially oriented polypropylene film (BOPP)

biaxially oriented polypropylene film is made by CO extruding polypropylene particles to form a sheet, and then stretching in both vertical and horizontal directions. Because of stretching molecular orientation, this film has good physical stability, mechanical strength, air tightness, high transparency and radiance, strong and wear-resistant. It is the most commonly used printing film at present. The thickness is usually 2. Only those who have known it for a certain amount have 0 ~ 40 m, and the most commonly used is 20 m. Biaxially stretched polypropylene film has the disadvantage of poor heat sealing, so it is usually used as the outer film of composite film. For example, after compounding with polyethylene film, the moisture resistance, transparency, strength, stiffness and printability are ideal, which is practical for holding dry food. Because the appearance of biaxially oriented polypropylene film is non-polar, they can design materials according to specific utilization, with high crystallinity and low appearance free energy. Therefore, its printing performance is poor and its adhesion to ink and adhesive is poor. It is necessary to carry out appearance treatment before printing and compounding

2. Low density polyethylene film (LDPE)

LDPE film is usually made by blow molding and tape casting. The thickness of cast polyethylene film is uniform, but it is rarely used at present because of its high cost. Blow molded polyethylene film is blown by blow molding machine with pressure control valve, pump regulator, pressure relay, flow control valve, travel switch, thermal relay and other signal devices of blow molding grade PE particles. It is the most widely used because of its low cost. Low density polyethylene film is a translucent, shiny, soft film, with excellent chemical stability, heat sealing, water resistance and moisture resistance, automatic shutdown, freezing resistance and boiling. Its disadvantage is that it has poor isolation from oxygen. It is often used as the inner film of composite flexible packaging materials. It is also the most widely used and most used plastic packaging film at present, accounting for more than 40% of the consumption of plastic packaging film

because polyethylene molecules do not contain polar groups, and have high crystallinity and low appearance free energy, the film has poor printing performance and poor adhesion to ink and adhesive. Therefore, it is necessary to carry out appearance treatment before printing and compounding

3. Polyester film (PET)

polyester film is made of polyethylene terephthalate, which is extruded into thick sheets and then biaxially stretched. 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, good chemical resistance, oil resistance, air tightness and fragrance retention. It is one of the commonly used barrier composite film substrates. However, the cost of polyester film is high, usually 12mm thick. It is often used as the outer material of cooking packaging, and has good printability

4. Nylon film (PA)

nylon film is a very solid film, with good transparency, good light, high tensile strength, high tensile strength, good heat resistance, cold resistance, oil resistance and organic solvent resistance, excellent wear resistance, puncture resistance, soft specific force, excellent oxygen resistance, but poor isolation to water vapor, high moisture absorption, moisture permeability, poor heat sealing, It is suitable for packaging hard goods, such as greasy food, meat products, fried food, vacuum packaged food, cooked food, etc

5. Cast polypropylene film (CPP)

cast polypropylene film is a polypropylene film produced by the casting process, which can be divided into ordinary CPP and cooking CPP. It has excellent transparency, symmetrical thickness, and symmetrical vertical and horizontal performance. It is usually used as the inner material of composite film. The thickness of ordinary CPP film is usually between 25 ~ 50 m. after compounding with OPP, it has good transparency, bright appearance and strong hand feel. This kind of material is usually accepted in gift bags. The film also has good heat sealing property. The thickness of cooking grade CPP film is usually between 60 ~ 80 m, which can withstand high-temperature cooking at 121 ℃ for 30 minutes. It has good oil resistance, air tightness and high heat sealing strength. Generally, the inner layer of meat packaging accepts cooking grade CPP film

6. Aluminized film

at present, the most widely used aluminized films include polyester aluminized film (VMPET) and CPP aluminized film (VMCPP). Aluminized film has the characteristics of both plastic film and metal. The function of aluminum plating on the appearance 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 certainly replaces aluminum foil, and also has low price, elegance and good insulation performance. Therefore, aluminum plating film is widely used in composite packaging. At present, it is intensively used in dry and expanded food packaging such as biscuits, as well as the outer packaging of some medicines and cosmetics

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