Plastic multi-layer co-extrusion technology appeared in the 1960s. After 60 years of development, it has been applied to various fields of plastic products forming a huge system. It has shown great advantages in packaging materials, building materials, daily life plastic products, etc.
In order to fully understand the system, it is necessary to summarize and classify the products produced by this technology. Due to different starting points, the methods of induction and classification are different. The following is a comprehensive introduction to several classification methods.
1. According to the shape
According to the shape of the formed material, it can be divided into multi-layer co-extrusion plastic film, multi-layer co-extrusion plastic sheet, multi-layer co-extrusion plastic container, multi-layer co-extrusion plastic profile, etc.
2. According to the molding method
According to the molding method, it can be divided into multi-layer co-extrusion tubular blow molding, multi-layer co-extrusion die casting, multi-layer co-extrusion profile molding, etc.
3. According to the types of Plastic
According to the types of plastics co-extrusion, it can be divided into co-extrusion of the same type of plastics and co-extrusion of different types of plastics.
- Multi-layer co-extrusion of different types of plastics. For example, polyethylene plastics have HDPE, LDPE, LLDPE. Each model has many varieties, and each variety has many grades. Multi-layer co-extrusion can be carried out between HDPE and LDPE, and it can also be carried out between LDPE resins of different grades in the same type.
- Multi-layer co-extrusion of polyolefin resins. Multi-layer co-extrusion of different types of polyolefin resins, such as PE, EVA, PP, etc.
- Multi-layer co-extrusion between different types of hot-melt polymers. Different types of resins with hot-melt properties, such as polyolefin, polyester, heterocyclic resins can be co-extruded. The most representative products are high-barrier resins PA, PVDC, EVOH as middle layer to be co-extruded with polyolefin PP and PE as the surface and inner layers.
4. According to the number of layers
According to the number of layers of co-extrusion materials, it can be divided into 2-layer co-extrusion, 3-layer co-extrusion, 4-layer co-extrusion, 5-layer co-extrusion, and even more than a dozen layers of co-extrusion. The number of layers includes all resin layers, whether it is the thickest resin layer or the thinnest resin layer, as well as the structural resin layer and the adhesive resin layer.