Plastic packaging film

Plastic packaging and plastic packaging products are taking an increasing share in the market, especially composite plastic flexible packaging, which has been widely used in food, medicine, chemical industry and other fields, among which food packaging accounts for the largest proportion, such as beverage packaging, frozen food packaging, cooked food packaging, fast food packaging, etc. These products have brought great convenience to people's lives.

Several common films

PVA coated high barrier film

PVA coated high barrier film is printed and compounded by coating PVA with nano inorganic substances on the polyethylene film. It solves the technical bottleneck of poor barrier performance of three-layer polyethylene co extrusion packaging film at present, without significantly increasing the cost. PVA coated high barrier milk film has been comprehensively introduced to the market. In the past two years, some domestic dairy products processing enterprises have used high barrier film on aseptic packaging, and the oxygen resistance rate is less than 5cm3/(m3 · 24h · 0.1MPa). Its barrier performance is not only significantly better than EVOH five layer co extrusion Baili bag, but also the packaging cost has decreased significantly. The cost of 320mmx110mm aseptic packaging film is about 0.07 yuan/piece, which is more than 45% lower than the cost of EVOH five layer co extrusion Baili bag. This not only ensures all the quality requirements of dairy products for aseptic packaging, but also significantly reduces the cost of aseptic packaging for dairy products processing enterprises.

Biaxially oriented polypropylene film (BOPP)

Biaxially oriented polypropylene film is made by co extruding polypropylene particles into sheets, and then stretching in both vertical and horizontal directions. Due to the tensile molecular orientation, this kind of film has good physical stability, mechanical strength, air tightness, high transparency and glossiness, and is tough and wear-resistant. It is the most widely used printing film at present, with a thickness of 20-40 μ  m. The most widely used is 20 μ  m 。 The main disadvantage of biaxially oriented polypropylene film is its poor heat sealing property. Therefore, it is generally used as the outer film of composite film. For example, the moisture-proof property, transparency, strength, stiffness and printability of composite film with polyethylene film are ideal, and it is suitable for containing dry food. As the surface of biaxially oriented polypropylene film is non-polar, with high crystallinity and low surface free energy, its printing performance is poor, and its adhesion to ink and adhesive is poor, so surface treatment is required before printing and laminating.

Low density polyethylene film (LDPE)

Low density polyethylene film is generally made by blow molding and tape casting. The thickness of cast polyethylene film is uniform, but it is rarely used at present due to its high price. Blown polyethylene film is blown by blow molding grade PE particles through a blow molding machine, with low cost, so it is most widely used. Low density polyethylene (LDPE) film is a translucent, shiny, soft film with excellent chemical stability, heat sealing, water resistance, moisture resistance, freezing resistance and boiling. Its main disadvantage is its poor oxygen barrier, which is commonly used in the inner film of composite flexible packaging materials. It is also the most widely used plastic packaging film with the largest consumption at present, accounting for more than 40% of the consumption of plastic packaging film.

Because polyethylene molecule does not contain polar groups, and has high crystallinity and low surface free energy, the printing performance of the film is poor, and the adhesion to ink and adhesive is poor, so surface treatment is required before printing and composite.

Polyester film (PET)

Polyester film is made of polyethylene terephthalate as raw material, which is extruded into thick sheets and then biaxially stretched. It is a colorless, transparent and glossy 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, the price of polyester film is relatively high, and the general thickness is 12 μ m. It is often used as the outer material of cooking packaging, with good printability.

Nylon film (PA)

Nylon film is a very tough film with good transparency, good luster, high tensile strength, high tensile strength, good heat resistance, cold resistance, oil resistance and organic solvent resistance, good abrasion resistance, puncture resistance, and soft, excellent oxygen resistance, but poor water vapor barrier, high moisture absorption, moisture permeability, poor heat sealing, suitable for packaging hard goods, such as greasy food Meat products, fried food, vacuum packaged food, cooking food, etc.

Cast polypropylene film (CPP)

Cast polypropylene film is a polypropylene film produced by tape casting process. It can also be divided into ordinary CPP and cooking CPP. It has excellent transparency, uniform thickness, and uniform performance in both vertical and horizontal directions. It is generally used as the inner layer material of composite film. The thickness of ordinary CPP film is generally 25~50 μ M, the transparency is good after compounding with OPP, the surface is bright, and the handle is firm. This material is used for general gift packaging bags. The film also has good heat sealing property. The thickness of cooking CPP film is generally 60-80 μ  It can withstand high temperature cooking at 121 ℃ for 30 minutes. It has good oil resistance, air tightness and high heat sealing strength. The inner layer of general meat packaging adopts cooking grade CPP film.

metalized film 

At present, the most widely used aluminized films mainly include polyester aluminized film (VMPET) and CPP aluminized film (VMCPP). The aluminized film has the characteristics of both plastic film and metal. The role of aluminum coating on the film surface is to block light and prevent ultraviolet radiation. It not only extends the shelf life of the contents, but also improves the brightness of the film. To a certain extent, it replaces aluminum foil, and also has cheap, beautiful and good barrier performance. Therefore, aluminum coating is widely used in composite packaging, mainly used in the packaging of dry and puffed food such as biscuits, as well as the external packaging of some medicines and cosmetics.