Extrusion laminating is a process related to extrusion coating, but the difference here is that extrusion-coated layer is used as an adhesive layer between two or more substrates. A secondary layer is applied to the extrusion coating while it is still hot. It further monitors the melt curtain before the chill roll before the sandwich is formed. The sandwich is then pressed together by pressure rolls. In addition to providing adhesion, the extrusion-coated layer may also serve as a moisture barrier.
In extrusion coating, resin is melted and formed into thin hot film. The plastic extruder measures the extruded film as it is coated onto a moving, flat substrate such as paper, paperboard, metal foil, or plastic film. The coated substrate then passes between a set of counter rotating rolls. The extrusion coated layer may protect a printed substrate or act as a moisture barrier which presses the coating onto the substrate to ensure complete contact and adhesion.
Co- Extrusion
The advantage of co-extrusion is that each ply of the laminate imparts a desired characteristic property, such as stiffness, heat-seal ability, impermeability or resistance to some area or environment.
The process of extruding two or more materials through a single die with two or more dies arranged so that the extruders merge and weld together into a laminar structure before chilling. Each material is fed to the die from a separate extrusion equipment, but the orifices may be arranged so that each extruder supplies two or more plies of the same material. Co-extrusion can be employed in film blowing, free film extrusion, and extrusion coating processes. The benefits of co-extrusion are that each ply of the laminate imparts a desired characteristic property, such as stiffness, heat-sealability, impermeability or resistance to some environment. All of pvc pipe extrusion line would be impossible to attain with any single material.
Foam Extrusion
During the chemical foam extrusion process chemical foaming and plastic resin agents are mixed and melted. The chemical foaming agent decomposes liberating gas which is dispersed in the polymer, melts and expands upon exiting the die. Due to the insulation properties of the foam structure foamed profile extrusions require more intense cooling than solid profiles.
Cast Film Extrusion
Process that involves the extrusion of polymer melts through a slot or flat die to form a thin, molten sheet or film. This film is “pinned” to the surface of a chill roll (typically water-cooled and chrome-plated) by a blast of air from an air knife or vacuum box. Process by which a polymer is extruded from a slot dies onto the surface of a water-cooled roll. Film is clearer and has more sparkle than blown film. Stretch film extruded by the cast method typically have greater tear resistance, greater aesthetic values and are quiet to unwind, which is not typically found in film manufactured by the blown method. Plastic film produced from synthetic resins (such as polyethylene) by the cast process. Stretch films manufactured by the cast film extrusion process are called cast films. In this process, the molten resin is extruded through a slot die onto an internally cooled chill roll.
Calendaring
Calendering is a process that usually uses four heated rolls rotating at slightly different speeds. PVC is the most commonly calendered material. Again the material is fed into the rolls, heated and melted, and then shaped into sheet or film.