Flat Die System uses Dow's Layer Multiplier design.

Press Release Summary:

Integrating layer multiplier technology into custom-engineered system that includes die, feedblock, and other tooling components, Flat Die System distributes complex structure into finished extrudate. It produces films and coatings with greater number of layers than conventional coextrusions, yielding microlayer structures that optimize moisture and gas barrier, and encapsulate gels and un-melts. With greater number of layers, likelihood of breakage caused by pinholes in film is minimized.

Original Press Release:

Dies that Coextrude up to 80 Exceedingly Thin Layers Raise Film and Coating Productivity, Lower Cost, and Boost Performance

Using Dow's 'Layer Multiplier' Design, EDI Builds Flat-Die Systems for Complex Structures with Standard Thickness but Many Microlayers, Substantially Improving Barrier Properties

CHICAGO, June 19, 2006: A potentially revolutionary flat-die system produces films and coatings with an order-of-magnitude greater number of layers than conventional coextrusions, yielding microlayer structures that improve moisture and gas barrier, encapsulate gels and "un-melts," and enable manufacturers to make more economical use of high-cost materials, it was announced at NPE 2006 by Extrusion Dies Industries, LLC (EDI), which is exhibiting at Booth 4661. Microlayer technology will become widely used in barrier packaging, according to EDI.

The technology is based on a patented "layer multiplier" system developed by The Dow Chemical Company and licensed from Dow by EDI. In a typical configuration, three or more extruders feed melt streams into an EDI-streamlined feedblock, which produces a uniform multi-layer "sandwich"; this in turn is fed into a layer-multiplier device built by EDI using Dow's patented design. In this device the layers are multiplied in stages: for example, three layers are multiplied into twelve, which are multiplied into forty-eight. The finished micro-layer structure is then distributed in an EDI coextrusion manifold to the target product width.

"We still do not know the practical upper limit," said EDI president and CEO Timothy C. Callahan, "but in my opinion it is possible to produce 50-micron film with 80 layers."

EDI's microlayer technology integrates the Dow layer multiplier into a complete custom-engineered system that includes the die, feedblock, and other tooling components for distributing the complex structure into a finished extrudate. The company will license the Dow technology to customers. "We are establishing relationships with licensees that enable film and coating processors to profit from the production economies and enhanced product performance made possible by the EDI / Dow multiplier system," Callahan said.

Microlayer Advantages Are Evident in Coextrusion Process and in End Use

As coextruded structures proliferate well beyond the standard limits of five, seven, or nine layers, here are some of the benefits cited by EDI:

o Enhanced barrier properties. The sheer increase in the number of barrier layers in the product yields an even more "torturous path" for gas and moisture molecules.

o Economizing on costly materials. Because many key properties of a polymer do not decrease proportionately with layer thickness, microlayer technology makes it possible to economize on costly high-performance resins while still achieving target properties. In oriented PET film, for example, layers of more expensive high-intrinsic viscosity (IV) resins can be combined with layers of low-IV grades. The resulting film properties are superior to those of film produced from a physical blend of high-IV and low-IV PET grades.

o Fewer web breaks. The greater the number of layers, the less the likelihood of breakage caused by pinholes in film, particularly in biaxially oriented products subjected to post-extrusion stretching. This is because the large number of layer-to-layer interfaces increases the chances for gels and other defects to be encapsulated and rendered harmless.

o New combinations of properties. The same polymer exerts different effects on end product properties according to whether it is distributed into one or two layers or into many super-thin layers. Layer-multiplier technology makes it possible to produce film that is more flexible, for example, without reducing the overall amount of a rigid polymer used as one of the raw materials. One benefit is greater processing latitude in subsequent thermoforming processes.

"EDI sees much of the barrier packaging sector adopting layer-multiplier technology in coming years," Callahan said. "Microlayer coextrusion also promises to speed the incorporation of nanocomposites in food packaging for enhanced barrier, thermal, and mechanical properties."

Technology Used in EDI Microlayer Systems Is Already Commercially Proven

Dow's patent history for its layer-multiplier technology goes back many years, Callahan pointed out, and the technology is being used very successfully by 3M Corp. for a wide range of sophisticated optical films in electronic screen displays and other products. Excluding such polymeric reflective films, the license granted to EDI applies to cast film, oriented film, sheet, and extrusion coating, primarily focused on the packaging sector.

The Dow technology is the best system available for extruding micro-layer products, according to Callahan. "Because layer multiplication requires that a layer structure travel a greater distance than in conventional coextrusion, there is a greater tendency toward viscous encapsulation of one layer material by another," he said. "The Dow technology meets this challenge more efficiently than other systems."

The key role of EDI will be to make the Dow technology commercially accessible to extrusion processors and web converters, according to Callahan. The tasks carried out for each customer by EDI in its role of system integrator will include: 1) designing feedblocks to present the proper layer structure to the multiplier device, 2) engineering the multiplier device to provide the pressure drops and balanced polymer flow channels for combining materials of differing viscosities and flow rates, and 3) machining streamlined manifolds to distribute the microlayer structure to final width. To carry out this work at its Chippewa Falls, WI, U.S.A. world headquarters, EDI has built a 2,000 sq.ft. (190 sq.m) process development laboratory equipped to run a wide range of film and sheet structures.

Extrusion Dies Industries, LLC is a leading international supplier of flat dies for sheet, film, extrusion coating, slot die coating, and pelletizing. The company designs and manufactures dies, feedblocks, deckling systems, vacuum boxes, and related equipment. Its European subsidiary is EDI GmbH in Reichshof-Wehnrath, Germany. In the U.S.A. and Germany, EDI operates facilities dedicated to reworking its own dies and those built by other suppliers, and it has licensed a third rework facility in Japan. Headquartered in Chippewa Falls, Wisconsin, U.S.A., EDI sells half of its dies outside the United States. Visit www.extrusiondies.com and www.reworkdies.com. E-mail: sales@extrusiondies.com.

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