Extrusion coating is the coating of a molten web of synthetic resin onto a substrate material. It is a versatile coating technique used for the economic application of various plastics, notably polyethylene, onto paperboard, corrugated fiberboard, paper, aluminium foils, cellulose, Non-wovens, or plastic films.
Slot Die Coating (Extrusion Coating) Technology. Slot die coating technology is used to deposit a variety of liquid chemistries onto glass, stainless steel, and plastic substrates for the development and production of a broad range of applications. This is achieved through the precise metering the process fluid and dispensing it at a controlled.
- A hot melt slot die operates without the gap and nip arrangement of extrusion coating. This proximity coating arrangement, where the slot die lip faces are 1-2 times the coating thickness from the substrate, allow the slot die to operate without forming the edge bead.
- The Extrusion Coating Die. Precisely distributes the extrudate across a changeable exit width. Enable easy coating width changes. All rates converted to kg/h/mm die slot. Average rate 1.0kg/h/mm die slot. Draw Down Device Draw Down Rate = 25 m/min. Testing Rates.
- 1Process
Process[edit]
Coating[edit]
Slot Die Coating Systems
The actual process of extrusion coating involves extruding resin from a slot die at temperatures up to 320°C directly onto the moving web which may then passed through a nip consisting of a rubber covered pressure roller and a chrome plated cooling roll. The latter cools the molten film back into the solid state and also imparts the desired finish to the plastic surface. The web is normally run much faster than the speed at which the resin is extruded from the die, creating a coating thickness which is in proportion to the speed ratio and the slot gap. [1][2]
Laminating[edit]
Extrusion laminating is a similar process except that the extruded hot molten resin acts as the bonding medium to a second web of material.
Co-extrusion[edit]
Co-extrusion is, again, a similar process but with two, or more, extruders coupled to a single die head in which the individually extruded melts are brought together and finally extruded as a multi-layer film.
Uses[edit]
The market for extrusion coating includes a variety of end-use applications such as liquid packaging, photographic, flexible packaging, mill and industrial wrappings, transport packaging, sack linings, building, envelopes, medical/hygiene, and release base.
See also[edit]
References[edit]
- ^US6336988B1, Enlow, 'Extrusion coating process for making protective and decorative films', published 2002
- ^US2714571A, Irion, 'Process for bonding a polyethylene film to a fibrous web', published 1955
Slot Die Coating Technology
- Soroka, W, 'Fundamentals of Packaging Technology', IoPP, 2002, ISBN1-930268-25-4
- Gregory, B. H., 'Extrusion Coating', Trafford, 2007, ISBN978-1-4120-4072-3
- Yam, K. L., 'Encyclopedia of Packaging Technology', John Wiley & Sons, 2009, ISBN978-0-470-08704-6