Multi-layer casting process using a variety of plastic particles, plastic powder raw materials, through a number of extruders, each plastic melt plasticized, the supply of a die or distributor, the number of extruder Molten plastic synthesis after the supply die, further processing, prepared in multi-layer casting coextrusion film. Multi-layer casting coextrusion process is different from the dry process, without plastic particles made of thin film intermediate transition products, multi-layer casting co-extrusion process of economic and environmental protection.

Multi-layer casting coextrusion process in the flexible packaging production enterprises widely used, reaching 80%. Multi-layer casting coextrusion process using heterogeneous plastic resin raw material co-extrusion casting, resin polar polymer compounds and resin non-polar polymer compounds between the performance difference, can learn from each other, through the resin properties of different layers, common high barrier film is prepared for high barrier film packaging. Polyethylene PE, nylon PA, TIE, EVOH resin for multi-layer co-extruded film, for dairy products, jam, meat and other vacuum packaging.

Multi-layer casting coextrusion process is a number of extruders will be different functions of the resin were melt extrusion, through their respective flow in the die inside and outside the confluence, and then cast cooling composite, not only simplifies the production process, materials Less, lower raw material consumption and production costs. The use of multi-layer casting coextrusion process to produce similar structure of the casting coextrusion than other processes to save 30% of the production costs. Coextrusion Casting variety of resin materials in the molten state, in a die composite welding together, because the barrier material and heat sealing material compatibility is poor, so you must choose a good solvent. Such as co-extruded nylon-6 low-density polyethylene co-extruded film, with Bynel resin, using 11 extruders common composite die, can be extruded nylon / Bynel / LDPE11 layer composite film.At present, the typical co-extruded film structure is: tensile force layer / barrier layer / heat sealing layer / peelable layer. The main force layer is PP polypropylene, PE polyethylene, barrier layer EVOH, PA nylon, etc., heat sealing layer for HDPE, LDPE, LLDPE, CPP and so on. Resin between adjacent layers, such as poor compatibility need to add adhesive resin layer, according to the use of different materials made of different structure of the co-extruded film. Multi-layer casting co-extruded film with 11 layers of symmetrical structure and 11 layers to PA or EVOH as the barrier layer, PE for the heat sealing layer. From the functional combination, there are mainly barrier layer, heat sealing layer and adhesive resin layer, through the different combinations of polymers to meet the packaging film oxygen barrier, water vapor requirements, PA and EVOH resin raw materials for the middle barrier layer of multi-layer Casting is the fastest growing.

Barrier resin raw materials have good processing performance, to adapt to good co-extruded composite head of the technical requirements of mobility. Poor fluidity or fluidity between the resin is too large, due to laminar formation affect the barrier properties of the composite membrane. PE / PA nylon / EVOH structure on food flavor penetration from 5% to 1%. The thickness of each layer of the multi-layer cast coextrusion film is controlled by the speed of the extruder. The speed control of the extruder is very accurate and the degree of automation is high. Head design is also very critical, eleven layers of structural design of the nose forming the packaging film barrier and composite strength of the best.