Plastic packaging and plastic packaging products are occupying more and more market shares, especially flexible plastic composite packaging, which has been widely used in the food, medical, and chemical industries. Among them, food packaging accounts for the largest percentage, as are beverages. Packaging, fast frozen food packaging, steam food packaging, fast food packaging, etc., these products have brought great convenience to people's survival.
Biaxially oriented polypropylene film is made by co-extruding polypropylene particles to form a sheet, and then stretching them in two deflection directions. Due to the orientation of stretched molecules, this film has good physical stability, mechanical strength, air, transparency, and high gloss, strong and wear-resistant. It is the most widely used printing film at present, and its thickness is usually 20~40 μ m, the most common application is 20 μ m. The disadvantage of biaxed-oriented polypropylene film is poor heat sealing, so it is usually used as the outer film of composite film. For example, it is ideal for moisture resistance, transparency, strength, rigidity, and printability as it is composed with polyethylene film. They contain dry food. Because the appearance of biaxed-oriented polypropylene film is nonpolar, the crystallinity is high, and the free energy of the appearance is low. Therefore, its printing performance is poor, and the ink and adhesive adhesion is poor. It is necessary to get the appearance before printing and laminating. Deal with punishment.
Low-density polyethylene films are typically made from casting and casting processes. The thickness of the molded polyethylene film is symmetrical, but due to the high cost, it is rarely used currently. Blow molded polyethylene film is blown by PE grade particles molded through a molding machine. The cost is low, so it's the most popular. Low-density polyethylene film is a translucent, bright and soft film. It has excellent chemical stability, heat sealing, water and moisture resistance, freezing resistance, and can be boiled. Its serious disadvantage is that it has poor oxygen isolation. It is often used in the inner film of flexible composite packaging materials. It is also the most widely used and largest amount of plastic packaging film currently, accounting for about 40% of the consumption of plastic packaging film. .
Because the polyethylene molecule does not contain polar groups and has high crystallinity and low energy without sight, the film has poor printing performance and poor adhesion to inks and adhesives, so it is necessary before printing and lamination to bear the penalty of image processing.
Therefore, polyester film is made of polyethylene terephthalate, which is made into thick sheets by extrusion and then stretched biaxially. It is a colorless, transparent, bright film with excellent mechanical properties, high rigidity, hardness and durability, puncture resistance, abrasion resistance, high temperature and low temperature resistance, chemical resistance, oil resistance, air and odor retention Well, it is one of the commonly used barrier composite film substrates. But the price of polyester film is relatively high, usually with a thickness of 12 mm. It is often used as the outer layer of retort packaging and has better printability.
Nylon film is a very strong film with good transparency, good light, high tensile strength, high tensile strength and good heat resistance, cold resistance, oil resistance and resistance to organic solvents. Excellent abrasion resistance, puncture resistance and softness, excellent oxygen barrier, but poor water vapor insulation, high moisture absorption and moisture permeability, poor heat sealing, suitable for packaging hard items, for example fatty foods, meat products, fried foods, vacuum-packed foods, steamed foods, etc.
Molded polypropylene film is a polypropylene film produced by the molding process. It can be divided into regular CPP and cooking-grade CPP. It has excellent transparency, uniform thickness, and uniform longitudinal and transverse performance. It is usually used as the inside of composite film. Layer material. The thickness of ordinary CPP film is usually between 25-50μm. Once combined with OPP, the transparency is good, the appearance is bright, and the hand feels strong. Zak bags
