Equipment Solutions Incorporate Recycled Plastics into Wood and Fiberglass Composite Materials

Recycled Resin Prices Flatten Out

New systems to process mixed plastic waste and to upgrade it with fiberglass or wood flour were prominent at last June’s show in Chicago. Single-shaft rotary grinders made a strong showing as newer alternatives to conventional granulators and shredders.

Composites of wood flour and fiberglass generated much of the recycling excitement at NPE 2000 in Chicago last June. Such composites consume hundreds of millions of pounds per year of post-consumer plastics. They can dramatically enhance low-value waste streams, such as commingled post-consumer plastics, mixed post-industrial resin scrap, and even “polysludge”—the mix of plastic and paper recovered from recycling gable-top milk and juice cartons.

Most of the news in granulators and shredders at the show was reported in our July issue and won’t be repeated here. However, it’s worth noting that NPE demonstrated the rapid spread of single-rotor shredder technology, which was launched at NPE ’97 by four exhibitors and was shown by well over a dozen at NPE 2000. While most conventional granulators run at 300 to 500 rpm, several suppliers introduced single-shaft shredders that run at only 80 to 150 rpm for digesting big chunks like purgings.

There was also new technology on display in densifiers for reclaimed film and fiber, including what is believed to be the first densification process for nylon fiber.

Composites from scrap

Composite Technologies Corp. (CTC) exhibited its 15% glass-filled composite basketball backboards and snowboards, which together consume 12 million lb/yr of mostly post-industrial scrap together with some washed, commingled post-consumer plastics. The composite sheet is laminated with preprinted film for a cosmetic surface. CTC developed its own proprietary equipment for low-pressure extrusion of the plastic and glass into a vertical-clamp compression mold. However, CTC is now making its know-how available to others through a partnership with C.A. Lawton Co., which is supplying extrusion/compression molding systems for glass-reinforced thermoplastics. Lawton’s equipment was originally developed by Kannegiesser in Germany for reclaiming heavily filled automotive scrap.

Another new proprietary technology reduces the paper content of polysludge from 35% to less than 5%. The technology was developed by Extraction Technologies, a year-old start-up in Lawrenceville, Va. It uses washing and extrusion equipment from Sorema SrL of Italy (represented here by Common Sense Solutions), together with its own proprietary fiber-removal system. The first application for this relatively clean PE obtained from coated paperboard is composite decking (“plastic lumber”) from Trex Co., Winchester, Va. Trex consumes 200 million lb/yr of used plastic bags, shrink wrap, and other PE scrap, mostly for its Easy Care Decking, which contains about 50% wood flour.

Mixed-scrap extrusion

Besides Lawton and CTC, Starlinger of Austria (represented here by Arcadia) showed another low-pressure extrusion technology for recycling at NPE. Developed six months before the show, Starlinger’s IntruStar “intrusion” process runs heavily contaminated, mixed scrap through two extruders—first a 28:1 L/D extruder, then a 13:1 machine, with vacuum degassing in between. Material is finally extruded at low pressure through an open bore (no die) into profile-shaped molds. Starlinger recently sold one IntruStar system to a U.S. company in Mexico and two others to firms in South America and the U.K. The line is sized for outputs from 1000 to 1700 lb/hr.

A different but still unusual approach to mixed-waste extrusion was displayed at the show by the B.G. Plast unit of Bausano in Italy (represented in the U.S. by Tex America). Eco Pipe is a new 60-in. corrugated PE drainage pipe, made in France and Italy. The pipe’s single wall is a tri-extrusion made using three twin-screw extruders. The core (90%) is washed, but unseparated, post-consumer plastics, sandwiched between skins with inner and outer layers (5% each) of post-industrial regrind. The commingled core layer requires very specialized screws, say Bausano sources.

Single shafts on a roll

The market for single-shaft shredders (or “rotary grinders”) has grown from virtually nothing three to four years ago to about 500 machines a year now, estimates Len Beusse, CEO of ReTech Industries Inc., a pioneer in the field.

Granulators typically have one shaft turning at high rpm and low torque, producing small chips suitable for molding or extrusion. Shredders have two shafts turning at low rpm and high torque, precutting larger pieces, which then pass to a granulator. Single-shaft rotaries fall somewhere in between, cutting at low to medium speed and producing either shredder-sized chunks or smaller granules in one pass. Thus they can compete with both granulators and conventional shredders. Single-shaft rotaries generally have extra-large feed hoppers that can take in big, bulky parts, which are often held against the rotor by a ram feeder.

New introductions from some of the bigger players in single-shaft rotary shredders were described in our July report. These include ReTech, Expon-Holzmag, Lindner Maschinenfabrik GmbH of Austria (represented here by Blades Machinery), Granutech Saturn Systems, Shred-Tech, Vecoplan Maschinenfabrik GmbH of Germany (represented by Nordfab Systems), and Zeno-Zerkleinerungsmaschinenbau GmbH from Germany (represented by Eurohansa).

In addition to those, a number of other new single-shaft grinders turned up at the show. For example, Cresswood Recycling Systems introduced a low-speed model called the Sabercat for purgings and large parts. A Sabercat model HF5340 was shown with 37 knives on a 16-in.-diam. rotor. It can grind 2000 to 4000 lb/hr of PP to 1.5-in. chunks. Its modified V-rotor turns at 62 to 140 rpm. Cresswood is a 37-year-old builder of custom machines to grind asphalt and wood. This is its first shredder for plastics.

Granutech Saturn Systems, originally a maker of dual-rotor shredders, showed its new Roto-Grind single-rotor model for the first time at NPE. It comes in eight sizes from 10.5 to 30 in. rotor diam. and is ram-fed. It is designed for one-step grinding of PP purgings, film, and carpet fiber to finished granules.

Rotogran International introduced a new low-speed, single-shaft rotary called RotoShred. It is specially designed to grind small, heavy purgings and costs much less than a conventional granulator suited to that job. The smallest RotoShred has a 24-in. feed opening and a ram-fed rotor that turns at about 120 rpm. Prices start at $38,000. Its 1/2-in.-wide knives use off-the-shelf, carbide-steel cutting tips, which are normally used on machine tools and are much less expensive than specially machined tips. It has a PLC control and a metal detector that can shut the line down if material is contaminated.

Starlinger brought out its first single-shaft rotary grinder, available in three sizes with throughputs from 500 to 1700 lb/hr.

Vecoplan’s single-rotor Vortex shredder granulator, called the One-Step, was introduced to North America at NPE after two years’ testing in Europe. It takes thick purgings or long, solid parts and grinds them directly to 0.2-0.4 in. screen size. The One-Step is the only single-shaft rotary that can accomplish such dramatic size reduction in one step, according to the supplier.

Weima Maschinenbau GmbH of Germany has a new U.S. office in addition to its representative, Cutter Corp. Weima offers a new two-stage combination of its single-shaft rotary shredder and a small granulator. The low-speed (80-rpm) shredder was redesigned for easy cleaning. The front lifts for screen removal.

Zeno’s new single-rotor shredder has a 63 x 70 in. cutting chamber. A larger model with a 72 x 80 in. chamber was displayed by New Herbold at NPE mounted over a Herbold granulator. Zeno builds single-shaft rotary shredders with solid rotors of 24 and 28 in. diam., which is bigger than most other single rotors of 16 to 18 in. diam. Zeno has designed shredders up to giant sizes with 100- and 120-in. cutting chambers but only recently built one that large. A 100-in. machine is shredding 6500 lb/hr of film scrap in Pennsylvania. It has a 28-in.-diam. rotor weighing 26.4 tons and is rated for maximum throughput of 14,000 lb/hr.

NGR Next Generation Recyclingmaschinen GmbH of Austria (represented by PSI Polymer Systems) showed for the first time in the U.S. a single-shaft machine designed to shred and preheat scrap before it is fed to an integrated reclaim extruder.

SSI Shredding Systems Inc. showed its Uni-Shear machine, which has been out for 18 months. (It is also marketed by Conair under its own label.) This medium-speed unit comes with 10- to 20-in. rotors and cuts scrap to screen sizes of 3/8 to 6 in.

Chomping chunks

New equipment to grind purgings and other large chunks includes an unusual model not previously reported in our show coverage. Getecha GmbH of Germany (which has a new office here in the U.S.) showed here for the first time an unusual granulator with its rotor tilted up at a 45° angle in the cutting chamber, rather than horizontal. A projecting “stir stick” mounted on the rotor reportedly pulls material into the cutting area without bridging or jamming.

The company has sold over 15,000 of these “unjammable” ARG angled-rotor granulators worldwide for beside-the press grinding. They come in two sizes: ARG 77 has seven-blades on a 7-in.-diam. rotor with variable speed from 200 to 300 rpm. The ARG 1012 has 10 blades on a 12-in. rotor that turns at 380 rpm. A patented screen with angled perforations prevents long, thin sprues from falling through unchopped.

Cumberland Engineering Corp. showed its first Model 1828 I granulator, which can grind thermoformed sheet scrap. It has a rear feed roll and a motorized “screw-jack” opening—a feature usually found only on much larger granulators, Cumberland says.

For grinding small parts, sprues, and runners, Granutec introduced dual-speed capability on its model 810-Robo. The unit, which previously ran only at 500 rpm, can chop sprues at 200 rpm or parts at 400 rpm.

Granulators from Blackfriars Ltd. were displayed by its new U.S. rep, Polymer Machinery Co. The Model 62/60 sound-deadened unit shown has tangential feed and two flywheels.

Dycomet S.A. de C.V. of Mexico City (represented by D&K Enterprises) brought to NPE its new Pagani model EHDXL, a tangentially fed, hog-type granulator that comes in two sizes. The EHDXL 4060 has a 16-in. cutting circle and is 24 in. wide with 15 fly knives and two bed knives. The EHDXL 4090 is 36 in. wide and is armed with 25 fly knives and two bed knives.

MPG Service & Sales brought a new small granulator with replaceable blades on an angled rotor. It comes in two models, MP86N and MP812N, both aimed at cutting glass-filled, abrasive materials.

Washing/densifying news

P.R.T. srl of Italy (with U.S. offices at P.R.T. America Inc.) exhibited in the U.S. for the first time at NPE. It showed an industrial film reprocessing line, but also offers complete washing and drying lines for regrind.

Sorema showed a new system called the Tramu, which may be the first to densify nylon fiber continuously. The Tramu line starts with a short (10:1 L/D) extruder, which discharges molten globs from a coarse die into a cooled granulator. A Tramu line in Italy is running nylon fiber with very small I.V. loss, Sorema says. A version of the Tramu was first announced at K’98, but a new screw design since then allows it to process nylon fiber.

Erema’s new continuous densifier, Model KAG600/50, has “smart” controls that adjust the speed or even stop the machine based on sensing the amperage load. If amps drop, the controls feed more material. If the feed rate can’t be changed (when densifying edge trim, for example), the controls slow the densifier speed. If film extrusion halts, the line shuts down automatically.

A. Carnevalli & Cia. of Brazil demonstrated a new reprocessing line for printed film or bag scrap. Pre-shredded film is auger fed from a hopper mixer to a 2.3-in., 25:1 extruder, which is vacuum vented to draw off ink volatiles. This is followed by a water-ring pelletizer and centrifugal pellet dryer.

Munchy Ltd. in the U.K. (represented by Action Industries) has redesigned its reprocessing extruders with off-the-shelf touchscreen controls, a less expensive machine base, and other cost-saving features so as to cut the price of its 220-lb/hr model to $85,000 from $120,000.

Plasmac Ltd., also of the U.K., was at NPE for the first time with its U.S. distributor, Upstream Systems & Machinery. They showed the Compact C55 dual-diameter reclaim extruder and an Integra system for film shredding, compacting and palletizing. Plasmac builds extruders for 50 to 1600 lb/hr, on which Upstream Systems installs U.S. electronics.

Artec Maschinenbau GmbH of Austria (represented by Carolmac Corp.) introduced to the U.S. its dual-diameter extruder for film reprocessing.

Gamma Meccanica S.r.l. from Italy displayed a special feeder for fiber scrap developed last year and shown for the first time anywhere at NPE. The new feed hopper has two large augers, which feed carpet and yarn scrap without bridging. The company says it has a half dozen of the new machines operating in the U.S.