Explanation of common materials and packaging structure of flexible packaging

Flexible packaging refers to packaging that can change the shape of the container after filling or removing the contents. It is mostly used in the fast-moving consumer goods industry. In the dazzling supermarkets, the shelves are full of flexible packaging items. It is a variety of bags, boxes, sleeves, packages and other flexible packaging made of paper, fiber products, plastic films, aluminum foils, and other composite materials.

Generally, the materials of flexible packaging are mainly divided into two types: flexible packaging plastic films and flexible packaging composite materials.

1. The film substrates commonly used in flexible packaging are generally plastic films, which have good thermoplasticity, and are usually processed by extrusion casting, blow molding, and biaxial stretching.
①General plastic film: polyethylene film (LDPE, HDPE, LLDPE, VLDPE, mPE)
Polypropylene film (CPP, BOPP)
Polyvinyl Chloride Film (PVC)
Polyester (PET)
Polyamide film (PA) Polystyrene film (PS) Cellulose plastic film (PT)
②High-performance plastic film: polycarbonate film (PC)
Polyurethane film (PU)
③High barrier plastic film: polyvinylidene chloride (PVDC)
Ethylene-vinyl alcohol copolymer film (EVOH)

2. Flexible packaging composite material is to bond films of different properties together to form a unity in a certain way, to overcome their respective shortcomings and improve the performance of protective materials.
①There are many types of materials: according to the production process: dry composite film, extrusion composite film, solvent-free composite film, wet composite film, coating composite film, etc.

By material: paper composite material, aluminum foil composite material, plastic film composite material, fabric composite material, etc. By function: high barrier film, cooking film, antibacterial film, antistatic film, vacuum packaging film, modified atmosphere packaging film, etc. ②The structure of flexible packaging can be distinguished by outer layer, middle layer, adhesive layer, inner layer, etc.

Commonly used outer material: polyester, nylon, stretch polypropylene, paper, etc. Mainly used for: mechanical strength, heat resistance, printing performance, good optical performance.
Intermediate layer: mainly used for: barrier, light shielding, freshness preservation, strength, etc. Commonly used: aluminum foil, aluminized film (VMCPP VMPET), polyester (PET), nylon, polyvinylidene chloride home cloth film (KBOPP KPET KONY)
Inner layer: mainly suture, commonly used unstretched polypropylene (CPP), polyethylene (PE) and its modified materials.
Ink layer: image and text information transmission and color reproduction, increase promotion effect.

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