Plastic films can be seen everywhere in our daily life, such as plastic film, transparent adhesive, plastic bags, etc., which are more commonly used in agriculture. They all look same and feel same, which is why it is commonly assumed that they are all made from same kind of material, but they are not. The following editor will introduce you to types of films that we often have. If someone asks you in future, you can also show them. Maybe you will get a lot of praise. !

1. Biaxially oriented polypropylene (BOPP) film

Biaxial oriented polypropylene film is made by co-extrusion of polypropylene granules to form a sheet, followed by stretching in both vertical and horizontal directions. Due to orientation of stretched molecules, this film has good physical stability, mechanical strength, airtightness, high transparency and gloss, and is strong and wear resistant. At present, it is most widely used printing film, and total thickness is 20~40μm, most widely 20 µm is used. The main disadvantage of biaxially oriented polypropylene film is poor heat sealability, so it is usually used as outer film of composite film. For example, after compounding with polyethylene film, moisture resistance, transparency, strength, rigidity and printability are ideal. Suitable for storing dry food. Because surface of biaxially oriented polypropylene film is non-polar, with a high degree of crystallinity and low surface free energy, its printing performance is poor, and its adhesion to ink and adhesive is poor.

2. Low density polyethylene film (LDpe)

LDPE film is usually made by blow molding and injection molding. Cast PE film has a uniform thickness but is rarely used nowadays due to high cost. Blown PE film is made from blown PE particles blown by a blow molding machine, and has a low cost, so it is most widely used. Low density polyethylene film is a translucent, glossy, soft film with excellent chemical resistance, heat sealability, water and moisture resistance, frost resistance, boiling resistance. Its main disadvantage is that it has poor oxygen barrier properties. It is often used as inner layer film of composite flexible packaging materials, and is also currently most widely used and used plastic packaging film, accounting for about 40% consumption of plastic packaging film.

Because polyethylene molecules do not contain polar groups, and have high crystallinity and low free surface energy, print quality of film is poor, and adhesion to ink and glue is poor, so before printing and surface treatment, compounding is required.

3. Polyester film (PET)

Polyester film is a film material made from polyethylene terephthalate as a raw material, which is extruded into a thick sheet and then stretched along two axes. It is a colorless, transparent, glossy film with excellent mechanical properties, high rigidity, harddurability and impact strength, puncture resistance, abrasion resistance, high and low temperature resistance, chemical resistance, oil resistance, airtightness and odor retention. from widely used barrier composite film substrates. However, price of polyester film is relatively high, and total thickness is 12mm, it is often used as outer material of retort packaging and has good printing capabilities.

4. Nylon film (PA)

Nylon film is a very strong film with good transparency, good gloss, high tensile strength and tensile strength, and good heat resistance, cold resistance, oil resistance and organic resistance. Excellent solvent resistance, abrasion resistance, puncture resistance , relatively soft , excellent oxygen resistance but poor water vapor barrier properties, high moisture absorption, moisture permeability, poor heat sealability, suitable for packing solid foods such as fatty food, meat products, fried food, vacuum packaging, steamed food etc. .

5. Cast polypropylene film (CPP)

Cast polypropylene film is a cast polypropylene film. It can be divided into ordinary CPP and CPP for cooking. It has excellent transparency, uniform thickness and uniform vertical and horizontal properties. Commonly used as a composite film. , The material of inner layer of film. The thickness of ordinary CPP film is usually 25 to 50 µm. After mixing with OPP, transparency is better, surface is bright, and hand feels firm. This material is used in ordinary gift packaging bags. This film also has good heat sealability. Cooking CPP film is usually 60 to 80 microns thick and can withstand high temperature cooking at 121°C for 30 minutes. conventional meat packaging - use CPP film for cooking.

6. Aluminized film

Currently, most widely used aluminized films are Polyester Aluminized Film (VMPET) and CPP Aluminized Film (VMCPP). The aluminized film has both characteristics of a plastic film and characteristics of a metal. The role of aluminum coating on surface of film is to darken and prevent ultraviolet radiation, which not only prolongs shelf life of contents, but also improves brightness of film, replaces aluminum foil to a certain extent, and is also cheap, beautiful and good. The application of aluminized film in composite packaging is very extensive. At present, it is mainly used for packaging dry and fluffy products such as biscuits, as well as for outer packaging of some medicines. and cosmetics.