Common materials and future development trends of composite packaging bags
Composite packaging material refers to a packaging material in which thin and soft multi-layer materials are combined by a composite process, also called flexible packaging material, which is mainly composed of various plastic products.
Commonly used in moisturizing facial mask bag packaging, laundry detergent bags, snack bags, packaging clothes bags. . .
Today, I will mainly talk about the commonly used materials for these packaging bags:
1. Biaxially oriented polypropylene film (BOPP)
It is obtained by co-extruding polypropylene particles into sheets, and then stretching them in both vertical and horizontal directions. Due to the orientation of the stretched molecules, this film has good physical stability, mechanical strength, air tightness, high transparency and gloss, toughness, and wear resistance, and is the most widely used printing film at present. 40μm, the most widely used is 20μm.
The main disadvantage of biaxially oriented polypropylene film is poor heat sealing, so it is generally used as the outer film of the composite film. Such as: after compounding with polyethylene film, moisture resistance, transparency, strength, stiffness, and printability are ideal, suitable for holding dry food. Because the surface of the biaxially oriented polypropylene film is non-polar, high in crystallinity, and low in surface free energy, its printing performance is poor, and the adhesion to ink and adhesives is poor. deal with.
2. Cast polypropylene film (CPP)
It is a polypropylene film produced by a casting process and can be divided into ordinary CPP and cooking grade CPP. Excellent transparency, uniform thickness, and uniform vertical and horizontal properties are 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, the transparency is good, the surface is bright, and the hand feel is firm. This kind of material is used in general gift packaging bags, and this film also has good heat sealability.
The thickness of the cooking grade CPP film is generally between 60 and 80 μm, and it can withstand high temperature cooking at 121 ° C and 30 minutes. of CPP film.
3. Low-density polyethylene film (LDPE)
Low-density polyethylene films are generally made by blow molding and casting. Low-density polyethylene film is a translucent, glossy, soft-textured film with excellent chemical stability, heat-sealability, water resistance, and moisture resistance, freezing resistance, and can be boiled.
Its main disadvantage is that it has poor barrier properties to oxygen. It is often used in the inner film of composite flexible packaging materials, and it is also the most widely used and most used plastic packaging film, accounting for about 40% of the consumption of plastic packaging films...
Because polyethylene molecules do not contain polar groups and have high crystallinity and low surface free energy, the film has poor printing performance and poor adhesion to inks and adhesives. Surface treatment.
4. Polyester film (PET)
Polyester film is made of polyethylene terephthalate as raw material, made into a thick sheet by the extrusion method, and then made into film material by biaxial stretching.
It is a colorless, transparent, and glossy film with excellent mechanical properties, high rigidity, hardness and toughness, puncture resistance, friction resistance, high temperature and low-temperature resistance, chemical resistance, oil resistance, airtightness, and fragrance retention. Good, it is one of the commonly used barriers to composite film substrates. However, the price of polyester film is relatively high, and the general thickness is 12 μm.
5. Nylon film (PA)
Nylon film is a very tough film with good transparency, good gloss, high tensile strength and tensile strength, and good heat resistance, cold resistance, oil resistance, and organic solvent resistance. It has excellent abrasion resistance and puncture resistance and is relatively soft, and has excellent oxygen barrier properties, but has poor water vapor barrier properties, high moisture absorption, moisture permeability, and poor heat sealing properties. It is suitable for packaging hard items, such as greasy food, meat products, fried food, vacuum-packed food, retorted food, etc.
6. Aluminized film - polyester aluminized film (VMPET) and CPP aluminized film (VMCPP)
At present, the most widely used aluminized films are polyester aluminized film (VMPET) and CPP aluminized film (VMCPP). Aluminized film has both the characteristics of plastic film and the characteristics of the metal. The function of aluminum plating on the surface of the film is to block light and prevent ultraviolet radiation, which not only prolongs the shelf life of the contents but also improves the brightness of the film. It replaces aluminum foil to a certain extent. It also has better barrier properties. Aluminized films are widely used in composite packaging.
Today's common materials for daily bag packaging have been shared, and tomorrow we will share the future development trend of these bags!
