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Extrusion Coating Lamination Line woven sack, jumbo bag, fabric bag making machinery

May 27, 2014 • Mrunal Ramanuj

Extrusion Coating Lamination Line woven sack, jumbo bag, fabric bag making machinery

Extrusion coating lamination machine is suitable for woven sacks, tarpaulins, jumbo bags, cotton fabrics, jute, paper, aluminum foil, non woven, BOPP, polyester, coating pe

Extrusion Coating Lamination Line – Ocean Extrusions
extrusion lamination coating machine
PE Coating, Extrusion coating and lamination and poly coating machine … Coating Plant, Poly Coating Machine, and Extrusion Lamination machine

 

Process

Coating

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.

Laminating

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

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

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.

Industrial/Fabric extrusion coating and lamination
(Heavy gauge)

Overview

In the heavy gauge extrusion coating process, polymers are extruded through a flat die to form a melt curtain which is applied onto a substrate then rapidly quenched on a chill roll. Coatings produced can be mono or multilayer. Coating weight can as high as 60 osy (2000 gsm). In the extrusion lamination process, the extrudate is applied between two substrates.

Process

 (pellets, flakes, powders, liquids) are fed into at least one of our four extruders (two twin-screw extruders and two single-screw extruders). Our twin-screw extruders (TSE’s) are equipped with gear pumps for direct extrusion; however, we also offer off-line compounding services. When TSE’s are used for extrusion of a single resin or an easy to disperse blend, we use a gentle screw configuration. This allows us to use our TSE as single screw extruder with better melt temperature control and optional atmospheric and/or vacuum venting of volatiles.

Materials are extruded through one of our two dies, either a 48″ single manifold die or a 36″ triple manifold die. Each die is fed through a five-layer feedblock; the triple-manifold die is equipped with two bypass channels as well, for co-extrusion of up to seven layers. Various selector plug cartridges allow for a wide range of layer configurations. Coating profile can be controlled either manually or automatically thanks to on-line beta gauge measurements.

A substrate (film, non-woven, paper, aluminium, etc.) is unwound from an unwind unit and the melt curtain is applied to the substrate on ourcoating unit. The substrate and extrudate are nipped between a rubber coated roll and a steel roll. Matte and polished finishes are available, and the coating unit position can be adjusted in both the horizontal and vertical directions. A second unwind unit is available for extrusion lamination as well.

After gauging and edge-trimming, the coated structure can be wound on a turret winder, or fixed position winder, or cut into slabs with a shear cutter, depending on the thickness and stiffness of the material.

Extrusion Coating / Lamination Unit

Our extrusion coating / lamination unit is equipped with two individually driven and temperature-controlled rolls and a non-driven, temperature controlled rubber-coated roll (temperature range from 15-130°C, 60-265°F; line speed from 0.15 to 100 m/min, 0.5 to 325 fpm). Nip pressure can be controlled up to 240 PLI (for a 36” wide structure). Matte and polished finishes are available for the entire thickness range, and embossing is possible as well.

Gauges

The line is equipped with EGS Gauging’s System 21 Measurement and Control System, including:

  • Two Mark III Industrial Scanner frames
  • Two beta gauges : Sr 90 and Kr 85
  • One Full Spectrum Infrared sensor
  • EGS Gauging’s AutoGaugeTM automatic profile control

The strontium-90 gauge is typically used for webs in the range 50-7500 gsm (1.5 – 220 osy). The krypton-85 gauge is used for thinner webs, in the range 10-1000 gsm / (0.3 – 30 osy). The two gauges can be used together, for example to measure a film profile before and after MDO stretching, or, in an extrusion coating process, to measure the coating thickness alone (by measuring the substrate alone with the Kr gauge and the coated product with the Sr gauge)

 

 

 

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For Extrusion Coating problems there exist numerous very
valuable trouble shoot guides, which often concentrate on
a specific field of interest.
In this presentation you will find in addition a selection of
experienced phenomena, where chemical and physical
analytical support helped a great deal in creating insight
in these selected phenomena and leading to problem
solving

Extrusion Coating. By concentrating on the most
demanding segments in the Extrusion Coating Market, we
created in close co-operation with our customers a
number one quality product, which is applicable in almost
every Extrusion Coating application.
In this product development process it was crucial to
carefully analyse the experienced problems, in order to
distinguish between specific polymer related and machine
related problems.

The direct material check will provide info about the structure
of the polymer and offers possibilities to predict the behaviour
of the product during and after processing. In short key words:
Density: Mechanical properties (e.g. rigidity, surface printing,
curling, friction), heat load.
MFR: Mechanical properties, sealing, neck in.
Swell Ratio: High swell – Long Chain Branching – low neck in.
Gel count: Superficial imperfections, Streaks, holes.
SEC MALLS: MWD info concerning High Molecular part (incl.
Branching) is essential to predict processing behaviour.
C5 extraction: Essential fraction for organoleptic prediction.
C6 extraction: Indication for waxes and volatiles
(environment).
GC headspace: In search of special volatiles related to
organoleptic performance and environment.
Unsaturations: Unsaturations are relatively over represented in
the lower molecular region (sensitivity for oxidation).
Granulate: Particle Size and Shape Distribution (PSSD) qualify
the pellet quality = equal feeding of the extruder feed zone.Technical Marketing PE 8
Trouble shooting in Extrusion Coating
2. Dynamic tests
• Shear curves
• DMS
• Rheotens
• Melt Extension Ratio (MER=melt elongation)
• Melt Extension Force (MEF=melt strength)
• Brabender test: determining MFR before / MFR after k

Shear curves: Important info to predict rheological
behaviour in equipment both for mono and co-extrusion.
DMS: Dynamic Mechanical Spectroscopy gives insight in
elastic behaviour of the polymer.
MEF and MER: Prediction of Draw Down and Neck-in
behaviour.
Brabender test: Submission to shear at defined
temperature and residence time to indicate processing
stability of the polymer.

Trials on the Pilot Extrusion Coating Line provides direct
practical info about the processing characteristics. The
resulting coated products can be examined for e.g. degree
of oxidation in order to create insight in the processing
temperature effects on the polymer, thus predicting e.g.
printability and seal ability. A comparison of polymer
properties before and after coating can be of importance.

Organoleptic evaluation by a professional Taste Panel,
whereby sample preparation and water incubation
procedures are very important.

Irregular pellet size, broad particle size distribution, fines and dust may
disturb the feed, giving rise to irregular extruder output. When working at
high capacity, the pellet quality is essential to guarantee a steady flow of
polymer into the feed zone of the extruder.
Edge waving may occur when the polymer reaches its draw down limit
When working at high capacity, the pellet quality is essential to guarantee
a steady flow of polymer into the feed zone of the extruder.
Screw geometry has to be fit for the specific polymer. A well designed
balance between feed, compression and metering zone will give constant
output.
The outlet of the extruder in general shows a very irregular transverse
temperature profile. This irregular profile has to be equalised in the static
mixer in order to prevent uneven flow out of the die due to melt
temperature differences.
Web temperature profile can also influenced by improper functioning of
the heating elements. In addition it must be clear, that the desired melt
temperature must be reached in the outlet of the extruder; in adapter and
die only minimal temperature corrections are allowed, as heat transfer in
these parts is very poor.
Improper heated or fouled deckled die spaces may contain a mix of wax
and cross linked products. When flowing to the die outlet these products
with high viscosity differences cause irregular flows.
Deckle geometry, material and the surface quality of it determine the
sticking of polymer to the surface. A fouled deckle negatively influences
the polymer outlet flow profile.Technical Marketing PE 13

Minimising dust, good house keeping and clean, well
maintained equipment are the key words in this case

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