At present, the plastic packaging commonly used on the market is generally multi-layer composite packaging. In popular terms, it is to compound film materials of different properties together, and play the role of protecting products and modifying products through the superposition and fusion of material properties. Generally speaking, the common composite material has two layers, three layers, four layers, etc., according to the performance characteristics of the outer layer, the middle layer and the inner layer, then the film of each layer, respectively, why the material? What kind of role does it play? Let's take a look.
First, the outermost layer, also known as the printing layer, the base layer, the need for good printing performance, good optical properties of materials, of course, heat resistance, mechanical strength is also good, such as BOPP (stretched polypropylene), BOPET, BOPA, MT, KOP, KPET, polyester (PET), nylon (NY), paper and other materials.
Second, the middle layer, also known as the barrier layer, this layer is commonly used to strengthen a certain characteristic of the composite structure, which requires good resistance and good poly moisture-proof function. At present, more common in the market are aluminum foil (AL), aluminum plated film (VMCPP, VMPET), polyester (PET), nylon (NY), polyvinylidene chloride coated film (KBOPP, KPET, KONY), EV and so on.
Third, the third layer is also the inner material, also known as the heat sealing layer. The inner structure is generally in direct contact with the product, so the material requires adaptability, permeability resistance, good heat sealing, as well as transparency, open-day and other functions. If it is packaged food also need non-toxic, tasteless, water resistance, oil resistance, commonly used materials are LDPE, LLDPE, MLLDPE, CPP, VMCPP, EVA (ethylene-vinyl acetate copolymer), EAA, E-MAA, EMA, EBA, polyethylene (PE) and its modified materials.
Common combinations of these materials include the following:
1.BOPP/VMPP, PET/CPP, commonly used in moisture-proof, puffed food, dry goods and powder products packaging.
2. Commonly used material combination of aluminized bags: BOPP/VMPET aluminized /PE or CPP, PET/VMPET aluminized /PE or CPP, BOPP/AL/LDPE.
3.BOPP/CPP, BOPP/LDPE, PET/PE, these plastic bags are mainly used for ordinary food and daily necessities packaging.
4.PA/ cooking CPP, PET/PA/ cooking CPP, PET/AL/ cooking CPP, suitable for high temperature cooking products.
5.PET/MPET/LDPE or CPP, BOPP/VMPET aluminum plated /LDPE or CPP, generally used for product packaging that needs to maintain fragrance.
6.PET/PA/LDPE can be used for foods that require refrigeration.
7.PET/AL/LDPE is a common combination of materials for aluminum foil bags.
Therefore, when customizing plastic bags, composite films can be selected according to product characteristics to achieve better adaptation.
