Extrusion.

As always, the show featured plenty of news for all sorts of extrusion processors. Most notably, several offerings underscored the show's prevailing recycling theme. Other new introductions and refinements were in dies, extruders and downstream equipment for blown film, cast film, sheet, pipe and profiles.

REPROCESSING UNDRIED PET

On the recycling front, Werner & Pfleiderer attracted considerable attention with a system for making PET film from regrind without any pre-drying. PET flakes containing up to 0.4% moisture were fed directly into a ZSK-40 40-mm twin-screw extruder. After the melting stage, three heated degassing ports remove moisture to a final humidity of 50 ppm. The ports themselves are located on the side rather than the top of the extruder to keep degraded polymer and condensate from falling back into the melt stream. As for melt quality, the company says the system's particular screw configuration and inherently short residence time hold the drop in I.V. to only 1-5%. Meanwhile, sister company Krupp Bellaform offers compatible in-line thermoforming equipment for turning the recycled PET into deep-drawn products. A W&P official hinted that the company is considering the possibility of mounting a ZSK atop a PET injection-stretch-blow machine to run recycle.

In other recycling news, the Direct Extrusion System (DES) from Erema GmbH and Reifenhauser GmbH made its first appearance at the Reifenhauser lab facility in Troisdorf (for details, see PT, Oct. '92, p. 12). At the show itself, Erema (which has a new U.S. office) showed two pieces of new equipment that enable its "dry" recycling equipment to extrude blown film without any intermediate pelletizing: First, a new gear pump ensures the constant output needed to make film. Second, the new Laser Filter's perforated drum removes impurities as the polymer runs through at least 250,000 laser-drilled holes (PT, Oct., '92, p. 12). Erema North America's sales and marketing v.p. Tim Hanrahan notes that front end of this system can work with nearly any extrusion suppliers' blown film dies and downstream equipment. But to preserve its edge as the supplier of the downstream side, Reifenhauser has developed a new die concept specifically for the direct extrusion line. According to U.S. product manager Hector Marchand, Reifenhauser's new recycling die splits the melt steam in half, creating a film structure of two identical layers. Any film defects, such as gels, would then be isolated in a single layer where they're unlikely to impair functionality.

Kuhne Anlagenbau (distributed by O/K International) had previously unveiled two new systems for producing blown film and cellulose-filled sheet from commingled reclaim (PT, Nov. '92, p. 17). At a location near the show, the company also demonstrated its new "intrusion process," which turns a commingled, unwashed waste stream into molded parts. First, a feeding device consisting of paddles and a "stuffing screw" fills the system's extruder, which in turn fills a stationary mold. To bring molding capacity up to the 1100-lb/hr extruder output, Kuhne has developed a rotary mold-filling valve that can distributes the melt between several stationary molds.

Another unusual approach to recycling comes from German extruder manufacturer Extrudex Gmbh. The company's Plastic Separation System TS 70 sits at the end of a recycling extruder and continuously removes metal, paper, wood and mineral contaminants from a thermoplastic melt stream. The filtered polymer proceeds out the front of the unit, which attaches directly to a pelletizing die. At the same time, the TS 70 uses a perpendicular screw to convey the contaminants out the side. Outputs run to 990 lb/hr. So far, the company has no representation in North America.

(For news in turnkey recycling systems, see Recycling section of this report.)

NEW FOR BLOWN FILM

Aside from the proliferation of automatic profile control systems from several companies (PT, Dec. '92, p. 17), other blown film news turned up as well. Alpine AG (Natick, Mass.) demonstrated several new products on a 90-mm HDPE line suitable for running post-consumer reclaim. A new line of compact oscillating haul-offs, the OH Series, which has no electronically driven turning bars for a web path that simplifies thread-up. It comes sized for layflat widths up to 1600 mm. Further upstream, the Dynasphere Cavity Transfer mixing section also made its show debut. It bolts onto the end of extruder to provide a more homogeneous melt when processing dissimilar materials, such as post-consumer reclaim. The Dynasphere also adds 4:1 L/D to the extruder, bringing it up to a 25:1.

Reasserting its presence in the HDPE market, Windmoeller & Hoelscher exhibited an HDPE blown film line with a 30:1 extruder. The company favors a unique bubble shape, in which the film reaches its full blowup ratio more gradually than in conventional HDPE bubbles. According to U.S. sales manager Andrew Wheeler, the new bubble shape has more than doubled the film's dart-impact resistance in tests on 8-micron film.

In other blown film news, Kiefel also showed its latest oscillating hauloff. The QAR is available for layflat widths between 800 and 2500 mm. It now hangs by a collar support.

Barmag AG has developed a coextrusion die that offers internal ventilation and layer centering through accessible outside bolts.

Also on hand was a blown film coextrusion kit from Egan Machinery. For roughly $189,000, processors can upgrade from mono- to multilayer processing. The kit includes a 2.5-6 in., 28:1 coextruder along with a three-layer coex die and air ring.

CAST FILM AND SHEET

Egan also dropped some "big" news on the show--a coextrusion laminating line that the company says is the world's largest at 145.7 in. wide. Sold to Wisapak, a laminated paper producer in Finland, the line runs at 1476 ft/min and 3300 lb/hr. Extrusion marketing manager Rick Keller says the line puts coatings as thin as 0.8 mils onto both sides of a paper substrate. Though the company had produced wider flat dies in the past, the challenge in this case was to spread such a thin polymer coating evenly over such a width. To accomplish this, Egan made some "subtle geometry changes" in its existing RV feedblock and Series 36 automatic die. Completing the line were one 6-in. and one 4.5-in. Powerflight extruders and a CMR control package.

Aside from the new auto-gauging system and new tool steel for its dies, both of which were discussed here last month (p. 19), Extrusion Dies, Inc. (EDI) also introduced a coextrusion feedblock called Ultra-Flow. It employs inserts shaped like miniature flat dies, which yield better layer distribution, the company says.

Welex Inc. introduced a new takeoff system for optical glazing and sheet 115 to 470 mils thick. The unit's bottom roll is offset from the other two vertical rolls to allow the sheet to enter at the optimum angle.

PIPE AND PROFILE

Targeting new markets for extrusion, Krupp Bellaform unveiled a pair of new systems. As a substitute for aluminum tubing, the E60 coextrusion line makes three-layer plastic tubes appropriate for the cosmetics industry. Coextrusion, explains sales and marketing director Alois Stadler, can add barrier properties or a glossy finish to the tubes--often prerequisites for cosmetics packaging. Typically, a layer of EVOH or nylon would be bonded to LDPE or HDPE with an adhesive tie layer. The line at the show was capable of 82 ft/min, according to Stadler. Further downstream, the line featured a brand new high-speed cutter. To eliminate burrs, this traveling cutter synchronizes its speed with that of the extrudate through an electronic link with the puller. And the cutting takes place around the parts' entire circumference to eliminate any deformation, says Stadler. The cutter works at rates of up to 130 cuts/min with an accuracy of |+ or -~12 mils. As for the puller, it now features an electric servo-motor control.

At its plant, Krupp displayed a line for extruding polymer pencils. In a single continuous process, the PE 7000 encases graphite with polymer, applies an outer color coating, sizes the emerging pencil, and cuts it to length. Equipment for secondary operations like sharpening, printing, and packaging is also available. Production rates run to roughly 7000 pencils/hr.

Krauss-Maffei showed an interesting coex window-profile line with recycling implications. At the show, it simply produced profiles with its 90-mm base extruder running a mix of virgin and regrind PVC while a secondary 40-mm unit added the capstock. But with more complex tooling, the line can also totally encapsulate the base profile within the capstock layer. This way, the frequently mottled reclaim from used window profiles can be buried underneath a cosmetically appealing virgin layer in new windows, says U.S. sales manager Hans-Jurgen Matthesius. One of the largest German window manufacturers, Kommerling, already has such a system for window recycling. The line was shown with the capstock extruder angled piggy-back atop the main extruder.

Krauss-Maffei additionally has improved its single-screw extruder output rates with a new screw design. For example, says Matthesius, a 3-in. extruder formerly producing 924 lb/hr of PVC can now achieve 1254 lb/hr using the new screw.

Cincinnati Milacron showed its new CMT 80-L conical twin-screw extruder, which has an 80-mm diam. at the discharge end and makes profiles at rates of 770 lb/hr. At the same time, it features low screw speeds to lessen the chance of overhearing the polymer; at 660 lb/hr, the machine requires a screw speed of only 20 rpm.

EXTRUSION AUXILIARIES

Cincinnati Milacron-Sano rolled out its new Harpoon line of single- and double-turret winders for blown and cast film between 50 and 130 in. wide. They feature a web path whereby the film runs vertically as it approaches the lay-on roll. This way, explains product manager Rich Previty, film tension does not change the roll's contact force. And because this web path is symmetrical, it allows consistent winding and slitting in forward or reverse modes.

The winder has also become more precise and compact through simplification of the web path, says Previty. Now, the tension roller sits immediately before the lay-on roll without any rollers in between. With extra rolls eliminated, tension can be measured as close as possible to the actual winding. Also, the Harpoon features a new servo-controlled linear in-feed carriage, which holds an independent slitting station, spreader roll and tension roll. Together these space-saving features result in a double-turret model that occupies the same space as earlier single-turret designs, the company says. Single-turret models can accommodate 31, 35 and 39 in. roll diam., while double-turret models come in a 31-in. size. Speeds run to 985 ft/min.

Nokia-Maillefer rolled out a revamped dual automatic coiler for flexible and semi-rigid tubes. The MW coilers, available for coil diam. from 31 to 62 in., now automatically perform measuring and cutting, changeovers from full to empty reel cores, coil strapping, and coil ejection. With its dual-reel cores, the unit simultaneously handles the coiling and strapping. As a result of the redesign, says business manager Franz Jermann, cycle times for strapping have dropped from 9 sec down to 4.5 sec. Production rates go up to 60 197 ft/min.

FMC ran its newest in-line bag-making equipment off a second Kiefel HDPE film line. This one-lane model 840/350 produces interleaved bags on a roll at speeds of 492 ft/min.

At K'92, W&H introduced its a surface/center winder called the Filmatic. It operates at speeds up to 1148 ft/min and accommodates widths from 47 to 129 in.