Co-extrusion flexible packaging production process big open, don't look at a pity!

Co-extrusion flexible packaging material is composed of multilayer plastic sheets or film, adopting flat extrusion or blowing process using two or more plastic resin by step into the legal system. So what's the process co-extrusion flexible packaging production process? This article will make a detailed answer! Co-extrusion flexible packaging material is composed of multilayer plastic sheets or film, adopting flat extrusion or blowing process using two or more plastic resin by step into the legal system. Co-extrusion film base material are never separated. Each kind of resin melt in the independent extruder respectively, and then melt through a total of extrusion die, and keep them in the layers of uniform and do not mix. Co-extrusion technology in the design, in order to prevent the mixing between layer and layer, should seriously consider the rheology of polymer, especially the flow pattern and the melt viscosity by a total of extrusion process and single-layer material after mold is the same. Because there are many materials squeezed together in together, if the viscosity is not enough, between two kinds of polymer bonding effect will influence the final product as a whole. Is the layer and layer under the condition of the force may separate. This kind of situation, will increase the third material, the glue layer, essentially it is a kind of thermoplastic adhesive. Through close bonding two materials, glue layer to maintain the integrity of multi-layer materials. Glue layer must also be in a dedicated extruder melt, increase as a separate layer into the mould. So many co-extrusion materials is a three layer structure, two kinds of plastic, and the third is the glue layer as the first two kind of material of adhesive material. On the structure more than four layers co-extrusion film is also very common. For example, if the EVOH included as impervious layer, then it is between two kinds of polymer to prevent moisture infiltration, so add glue layer, should be at least five layer structure. Although resin from single extruder melt can supply co-extrusion film structure of double or more layers, but each new type of resin in structure must have a dedicated extruder. Co-extrusion film or sheet is widely used in the packaging industry. Such as different inside and outside surface adhesion characteristics of pallet flexible packaging film; In an inner light brown proof polyethylene and inner and outer the beautiful appearance of white polyethylene co-extrusion film made of snack food bag, etc.