Is Thermoplastic RTM Close to Commercial?

By Jan H. Schut

For over 10 years R&D has gone on among European car makers, machine builders, material suppliers and research institutes to adapt conventional resin transfer molding machines from thermosets to thermoplastics. Instead of pumping two-component epoxy or PU into a mold to cure, they pump thermoplastic monomer with catalyst and activators into the mold to polymerize in situ. The goal for thermoplastic RTM is to mass produce continuous-glass-fiber-reinforced thermoplastic parts for cars, which would have advantages over thermosets of being tougher, stronger, weldable, and recyclable. T-RTM technologies are mostly focused on in situ molding of PA6 from epsilon-caprolactam monomer.

Because caprolactam has very low viscosity, it wets fiber structures rapidly in about 30 seconds without disturbing their position, achieving high directional fiber content of up to 65 volume %. Caprolactam, which melts at 69 C, comes either in liquid form in heated containers or in flake form. Usually two tanks are used in a modified RTM dosing machine. One tank is for caprolactam with catalyst, the other for caprolactam with activators and additives. The two caprolactam streams are combined typically 1:1 in a specially designed mixing head heated to around 100 C, then pumped into an RTM mold heated to around 150 C. The mix polymerizes in 2-5 minutes, depending on part characteristics and volume.

Caprolactam, however, isn’t easy to work with. It has very low, watery viscosity of 5-10 mPas vs 200-300 mPas for liquid PU, so leaks are an issue with conventional RTM machinery and molds designed for PU. Caprolactam also has to be protected from oxygen and moisture (<0.01%) throughout the in situ process since moisture slows or stops polymerization. So continuous fiber structures have to be predried before they’re put into the mold. PA 6 polymerizes to a solid using an anionic “ring-opening” polymerization reaction at over the melt temperature of the monomer, but below the melt temperature of the polymer.

LOTS OF EUROPEAN R&D

Among others, Porsche AG in Stuttgart, Germany (www.porsche.com), worked with the Fraunhofer Institute for Chemical Technology in Pfinztal, Germany (www.ict.fraunhofer.de), to develop “Cast Polyamide” thermoplastic RTM, shown at the JEC Composites show in Paris in 2006. Porsche and the Fraunhofer showed the process again in 2010 at a composites conference in Germany with a demo trunk liner for a Porsche Carrera 4, which weighed 50% less than an aluminum trunk liner.

Volkswagen AG in Wolfsburg, Germany (www.volkswagenag.com), which bought Porsche in 2012, recently successfully tested high-pressure thermoplastic RTM molding of continuous-glass-filled PA6 “B pillar” reinforcements that could be glued into steel B pillar frames and weigh 36% less than high-strength steel B pillars in production for the North American market. The tests were done in VW’s fiber-reinforced plastics test plant in Wolfsburg, Germany, and reported in Kunststoff magazine in March this year.

First an asymmetrical woven fiber structure with a sizing compatible with anionic polymerization of PA6 was preshaped in a separate mold with a binder, also compatible with caprolactam. Preforms were kept dry in a drying oven from HK-Praezionstechnik GmbH, Oberndorf am Neckar, Germany (www.hk-pt.de), then put into an RTM mold heated to 150 C. Molding was done on an existing 1000-ton injection molding machine, using a two-sided mold, modified to prevent leakage of caprolactam. Caprolactam injection must be moisture-free, so the mold was rinsed with nitrogen each time before filling.

KraussMaffei Technologies GmbH in Munich, Germany (www.kraussmaffeigroup.com), which worked with VW, developed a new high-pressure caprolactam mixing head, electrically heated to about 100 C and pumping with nearly 100 bars of pressure. KraussMaffei also modified its RTM machines for caprolactam with heated hoses to transfer melted caprolactam from dosing tanks to the mixing head. Even coupling pieces in the hoses needed heater cartridges to keep temperature constant. KraussMaffei already built caprolactam mixing heads and dosing machines for NYRIM, a reactive in situ casting process for PA6 copolymers, developed in the 1980s by Monsanto Co., St. Louis, MO (www.monsanto.com), then sold to DSM NV in the Netherlands (www.dsm.com). NYRIM puts caprolactam with activated elastomeric polymer in one tank and caprolactam with catalyst in the other, then mixes them.

Krauss Maffei developed a new high-pressure mixing head and modified RTM machines to mold reactive caprolactam with catalyst and activators in situ into PA6 parts. Thermoplastic RTM could mold series automotive parts with very high directional fiber contents up to 65%.

Hennecke GmbH, Sankt Augustin, Germany (www.hennecke.com), developed an even higher pressure T-RTM system. Hennecke optimized its counter flow RTM mixing head for thermoset PU to mix lower viscosity caprolactam. The high pressure caprolactam mixing head uses more than twice the pressure of Hennecke’s PU mixing head, which is roughly 200 bars. Hennecke’s caprolactam mixing head is self-cleaning only through counter flow.

Henecke

Hennecke developed a very high pressure T-RTM system, adapting its counter flow RTM mixing head to mix much lower viscosity caprolactam. Melted caprolactam has a watery viscosity of only 5-10 mPas, whereas liquid PU has a viscosity of 200-300 mPas.

Engel Austria GmbH, Schwertberg, Austria (www.engelglobal.com), worked with the Fraunhofer-ICT from 2009 to 2011 to develop a high pressure, servo-motor-powered thermoplastic RTM machine based on melting caprolactam flake in a modified injection molding unit, not on dosing liquid caprolactam from tanks. Engel uses an Engel e-victory injection molding machine with two injection units, modified for low viscosity caprolactam with special valves and seals. This was shown for the first time at an Engel open house in June, 2012, along with Engel’s in situ thermoplastic RIM process (see previous blog June 11, 2014), which is also based on injection molding of caprolactam.

Mahr Metering Systems GmbH, Goettingen, Germany (www.mahr.com), adapted a metering machine to process reactive PA for low-pressure T-RTM casting. Mahr also recently developed a new mixing head for caprolactam, catalyst and activator, which is self-cleaning using nitrogen. It was shown for the first time at the JEC Composites show in Paris in March. Mahr’s dynamic mixing head for T-RTM uses high-precision gear pumps for process pressure from 20 up to nearly 50 bars. It is also designed for three components instead of two, allowing caprolactam to be combined with catalyst, activators and colorants separately.

Mahr metering systems

Mahr Metering Systems developed a new low pressure mixing head for caprolactam, catalyst and activator, which is self-cleaning using nitrogen. It’s designed for three components instead of two, allowing caprolactam to be combined with catalyst, activators and colorants separately.

Resin suppliers are working on reactive caprolactam formulations. BASF SE, Ludwigshafen, Germany (www.basf.com) worked with VW and Krauss Maffei to develop reactive PA6 systems with caprolactam, catalyst, activators, and additives,. BASF has also done development work for low-pressure T-RTM with Mahr. Lanxess AG, Koeln, Germany (www.lanxess.com), has done development work with Engel on thermoplastic RIM PA6 (see blog June 11, 2014). Brueggemann Chemical, Heilbronn, Germany (www.brueggemann.com), which acquired DSM’s NYRIM business over a decade ago, has done development work with Hennecke.

No auto maker so far has announced plans to commercialize thermoplastic RTM. Cycle time is apparently still an issue for large production quantities. “Two to three minute cycle time is OK for 100,000 parts a year,” notes a researcher in in situ RTM at a major auto maker, “but not for 200,000 or 300,000 parts a year.” But a spokesperson from BASF thinks the first car parts could be in series production by 2018 or 2019.

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In Situ Molding Is More Than a Possibility

By Jan H. Schut

In situ molding could be the answer to mass producing engineering thermoplastic composites, especially metal-replacing structural parts for future cars. In situ molding mixes melted monomers of a polymer in two parts, one with catalyst, the other with activator, and puts them into a heated mold where they polymerize. For PA6 they polymerize at a temperature over the melt temperature of the monomer, but below the melt temperature of the polymer. The reaction is anionic “ring-opening” addition for PA 6 and PC or conventional chain addition for PA 6.6. Other condensation polymers that could potentially be molded in situ include PMMA, PBT, TPU, and PEK and copolymers are possible.

In situ thermoplastic reaction injection molding has been known for 50 years, primarily for nylon 6, but it’s done by a slow batch casting process with conventional RIM equipment. NYRIM, for example, is a PA6 copolymer system for thermoplastic RIM, commercialized in 1981 by DSM NV in the Netherlands (www.dsm.com), and acquired by Brueggemann Chemicals, Heilbronn, Germany (www.brueggemann.com) over 10 years ago. NYRIM combines caprolactam with different ratios of elastomeric prepolymer (7-40%) and polymerizes them into copolymers in situ using conventional RIM equipment. Caprolactam with activator is heated in one pot, elastomeric prepolymer with catalyst in another. They’re combined in a RIM mixing head and polymerized at low pressure in aluminum molds. It’s a niche process for specialty parts with high strength requirements and short production runs like treads for earth movers.

What’s new is in situ thermoplastic RIM based on conventional injection molding, which can be fully automated and fast enough for mass production for the first time. Three years ago Engel Austria GmbH in Schwertberg, Austria (www.engelglobal.com), built a prototype for the first reactive thermoplastic RIM machine for caprolactam using reciprocating screw injection units instead of heated tanks. Engel worked with the Fraunhofer Institute for Chemical Technology in Pfinztal, Germany (www.ict.fraunhofer.de), to develop the new approach.

The advantage of molding monomers is that they have much lower viscosity than polymers, so monomers can thoroughly impregnate dry continuous or woven fiber structures without disturbing fiber position. In situ molding can thus achieve directional woven fiber contents of up to 65 volume % and mold more complex shapes than viscous polymers. Compared to traditional thermoset RIM molding of epoxy and PU, continuous thermoplastic RIM has other advantages: short cycle times, greater toughness and impact strength, weldability, and recyclability. Below is the latest in thermoplastic RIM developments. The next blog will look at a similar surge of R&D in thermoplastic in situ RTM.

AUTOMATING IN SITU THERMOPLASTIC RIM

Engel’s in situ process for PA6 started as a PhD thesis by Lars Fredrik Berg at the Fraunhofer ICT, supervised by Peter Elsner at the Karlsruhe Institute of Technology in Germany (www.kit.edu), and Georg Steinbichler, head of R&D at Engel. Berg’s thesis, finished in 2011, yielded enabling machine developments, which Engel and the Fraunhofer continued to work on.

Engel built the first thermoplastic RIM machine based on conventional injection molding, with two reciprocating screw injection units instead of heated tanks. A sealing device in the barrel, developed at the Fraunhofer-ICT, meters very low viscosity caprolactam into the mixing head.

Engel built the first thermoplastic RIM machine based on conventional injection molding, with two reciprocating screw injection units instead of heated tanks. A sealing device in the barrel, developed at the Fraunhofer-ICT, meters very low viscosity caprolactam into the mixing head.

In 2011 Engel built a prototype for a commercial thermoplastic RIM machine using a modified tiebarless Engel e-victory reciprocating screw press with two all-electric injection units inclined at a 45 degree angle. One melts epsilon-caprolactam monomer (flake or pellets) with catalyst, the other melts caprolactam with activator. A non-return valve patented by Berg and the Fraunhofer (U.S. Pat. # 8684726) goes onto the end of the reciprocating screws and seals against the inside of the injection barrel, allowing precise feeding and injection of very low viscosity monomers. The two melts are combined in a high pressure mixing head and fed with very low pressure into a mold to cure.

Engel has a patent application on a way to make fiber composites or hybrid components (U.S. Pat. Applic. # 20130181373) using a modified high-pressure mixing head. Engel partnered with Hennecke GmbH, Sankt Augustin, Germany (www.hennecke.com) to optimize Hennecke’s high pressure RTM mixing head for PU for lower viscosity caprolactam instead. Caprolactam has a viscosity of 4mPas, so leakage was an issue. Hennecke developed new dynamic mixing technology for the high pressure, high temperature head for caprolactam. Throughout the molding process, caprolactam also has to be protected against moisture, since moisture absorption impedes or stops polymerization.

ENGEL automotive e-victory 120 combi in-situ-polymerisation 2

Engel’s injection molding machine for in situ RIM is adapted to mold low viscosity caprolactam, wetting out dry fiber inserts. This can achieve PA6 parts with continuous fiber content of up to 65 volume %, like this passenger car brake pedal insert and prototype athletic shin guard.

Engel’s injection molding machine for in situ RIM is adapted to mold low viscosity caprolactam, wetting out dry fiber inserts. This can achieve PA6 parts with continuous fiber content of up to 65 volume %, like this passenger car brake pedal insert and prototype athletic shin guard.

Engel’s injection molding-based RIM process was shown first at an Engel open house in June 2012, molding a continuous fiber PA6 insert for a passenger car brake pedal, developed with ZF Friedrichshafen AG in Friedrichshaven, Germany (www.zf.com). Then the IKV Institute of Plastics Processing RWTH in Aachen, Germany (www.ikv-aachen.de) and 14 partner companies worked with Engel to develop an automated in situ injection molding process combined with TPU overmolding, which was shown for the first time by the IKV at the K 2013 show in Germany. The automated process prototyped an athletic shin guard, starting with a woven fiber glass preform made of multiple layers, consolidated by a binder, robotically trimmed with ultrasonics, dried, and inserted robotically with needle grippers into heated injection molds. Temperature control is critical. Caprolactam melts in the injection barrels at about 70 C, passes through heated runners and the electrically heated mixing head at about 100 C, and into molds heated to about 150-160 C.

The IKV Institute worked with Engel to develop automation for Engel’s thermoplastic RIM press, molding a PA6 shin guard in situ with a continuous glass preform in under 3-minute cycles. It was shown for the first time by the IKV at the K 2013 show in Germany.

The IKV Institute worked with Engel to develop automation for Engel’s thermoplastic RIM press, molding a PA6 shin guard in situ with a continuous glass preform in under 3-minute cycles. It was shown for the first time by the IKV at the K 2013 show in Germany.

The two-cavity in situ molds for the shin guards were built by Schoefer GmbH in Schwertberg, Austria (www.schoefer.at), with a compression edge with silicone seals to contain the low viscosity monomers and to compress the fiber preform at the edges so that no flash forms. The e-caprolactam was specially developed for the application by LanXess AG in Koeln, Germany (www.lanxess.com). Cure time was below 3 minutes. In a separate injection molding machine the shin guards were over-molded on the back with soft-touch TPE.

Auto company interest in in situ molding is also visible. Toyota Motor Corp., Tokyo, Japan (www.toyota-global.com) got a patent years ago for in situ RIM molding of PC (U.S. Patent # 5514322), describing carbonate compounds with catalyst and activators, mixed and fed into a mold to polymerize. The patent says that the anionic addition reaction is controlled by the a third ingredient (BPh3 Lewis acid) so that the reaction starts inside the mold, not before. The patent cites 23 formulations of which the 23rd cures in situ in 4 minutes with thorough impregnating of continuous fibers and makes PC with molecular weight of 17,000. Another Toyota patent (JP Pat. # 194-157769) describes catalysts for in situ molding. It doesn’t appear that Toyota has applied in situ PC technology commercially, though light weight parts for the energy saving Prius would be a good candidate. The Prius-Alpha hybrid minivan already claims to have the largest PC panoramic roof in the world.

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How Multi-Shot Molding Is Becoming Multi-Process

By Jan H. Schut

The past three to six years have seen an astonishing burst of creativity in new multi-process, or hybrid, injection molding for large durable parts, especially automotive. Ignore the fact that some of these new machine concepts aren’t even half injection molding anymore. Big global automotive and electronics companies are buying into the idea and pushing developments in Europe and the Far East (not so far in North America). The concept started with large multi-shot parts made on rotating molds, which saved dramatically in cycle time and material cost. Then other processes were added to injection molding to make unusual high volume composites with even more dramatic potential weight and cost savings.

Multi-process molding combines thermoplastic injection with a wide range of other plastic processes in one machine and one mold, typically a rotary mold. Developmental “multi-process” molding machines, for example, combine injection molding with compression, foam, reaction injection molding (RIM), PUR foaming, glass-reinforced compounding, continuous fiber reinforcement, and vacuum forming. These processes have been serially combined for low volume composite parts like sports equipment for years, but combining them into one high-output machine is new.

A series of parts for Hyundai-Kia Automotive Group in Seoul, Korea (www.kia.com), shows how multi-process is evolving. When Hyundai made a soft-touch central console for a 2011 CUV using two-shot injection molding with a rotary mold, cycle time dropped from two hours to two minutes, and the part cost 20% less than the previous painted one. The two-shot technology, called “Dolphin,” was developed by automotive tool maker Georg Kaufmann Formenbau AG in Busslingen, Switzerland (www.gktool.ch), together with Engel Austria GmbH in Schwertberg, Austria (www.engelglobal.com).

Dolphin, which was launched in 2006, was also used for an interior desk part for a 2011 Mercedes Actros long-haul truck. The technology used two injection presses, sequential pressure, and rotary molds to form three layers with two materials: first a shot of rigid PC/ABS for the core, then a shot of solid, grained TPE for the skin with thickness adjusted by cooling time, then the same shot of TPE for microcellular foam in between, using MuCell technology from Trexel Inc., Wilmington, MA (www.trexel.com). The Mercedes truck part, which won an SPE Automotive Division prize in 2012, reduced process steps from eight to two and cost 25% less than the previous part.

Molder ABC Group Inc., Toronto, Ont. (www.abcgroupinc.com) and Delta Tooling Co., Auburn Hills, MI (www.deltatechgroup.com), also developed a patented alternative injection molding technology (U.S. Pat. # 8048347) for Ford Motor Co. Ford calls it SPT (structural plastic technology); Delta calls it STPO (structural thermoplastic polyolefin). By either name, the process molded a structural foam TPO rocker panel for a 2013 Ford Edge Sport model. First TPO with endothermic blowing agent was injected into the mold with nitrogen gas assist to fill thin-walled sections of the part first with solid TPO and get a paintable Class A surface. Then fill pressure was reduced, allowing foam to expand in thicker areas of the part forming a rigid cellular structure. Both Dolphin and SPT injection molding technologies form solid and foamed structures from the same shot in the same tool—they’re multi-step, but not multi-process.

Kaufmann’s next step was the patented Varysoft process (U.S. Pat. # 8512616), developed with Hyundai and introduced at an open house in 2010. Varysoft molded a demo instrument panel with three shots and three presses instead of two: first glass-filled ABS/PC substrate, then soft TPO skin, then TPE foam in between.

Developmental Varysoft technology, demonstrated at K 2013 by Engel and Swiss toolmaker Georg Kaufmann, can make soft touch interior automotive trim with three processes in a two-level, rotary stack mold. It combines vacuum-forming, injection molding, and PUR foam.

The next Varysoft technology, in development for Hyundai, goes further still. Instead of three shots, it uses three processes in a two-level rotary stack mold. Demonstrated by Engel at K 2013 in Germany, it makes the soft-touch surface with TPO film heated with an IR heater on top of the machine, then vacuum formed for surface texture on the upper level of the rotary mold. In a separate cavity the glass-filled ABS/PC substrate is injection/compression molded using MuCell microcellular foam. (MuCell typically shortens cooling time, uses about a third less clamp force, and saves about 10% in material.) The TPO skin and ABS/PC substrate are then brought together. The tool rotates 180 degrees, and the contoured space between skin and substrate is filled with PUR foam, injected with PUR foaming equipment from Hennecke GmbH, St. Augustin, Germany (www.hennecke.com). The demo part thus combines vacuum forming, thermoplastic injection/compression molding, and PUR foaming.

SOMEONE HAS TO BE FIRST

A seat pan for a 2013 Opel Astra sedan is believed to be the first multi-process part actually in commercial series production. It’s made with an unusual continuous fiber composite technology from Reinert Kunststofftechnik GmbH in Bissingen an der Teck, Germany (www.reinert-kunststofftechnik.de). The technology combines two processes in one complex linear mold with sliders, built by Maier Formenbau GmbH, also in Bissingen (www.maier-formenbau.de). First, a precut continuous glass fiber insert, pre-impregnated with nylon, is heated with an IR heater inside the mold. When the prepreg is hot and soft, something like a wet towel, it’s formed between the mold halves. Then it’s over-molded with short-glass-filled PA6 to fill out the part geometry. The same tool shapes the hot prepreg and overmolds it, achieving a weld-like bond between the two materials. The PA6 composite replaces a heavier conventional glass-filled plastic part (PA6 with 50% glass fiber and 2.5 mm thick) with 45% weight saving. Reinert also uses the technology to combine PP-impregnated fiber prepregs with glass-filled PP.

This seat pan made by Reinert in Germany for a 2013 Opel Astra sedan is believed to be the first commercial multi-process part. The technology heats and shapes a continuous glass/PA6 prepreg between mold halves, then overmolds the hot prepreg with glass-filled PA6 in the same tool.

This seat pan made by Reinert in Germany for a 2013 Opel Astra sedan is believed to be the first commercial multi-process part. The technology heats and shapes a continuous glass/PA6 prepreg between mold halves, then overmolds the hot prepreg with glass-filled PA6 in the same tool.

Composite molding machines also use rapid mold heating and cooling, such as “water/water” molds with heating and cooling lines and induction heated molds from RocTool S.A., Le Bourget du Lac, France (www.roctool.com), to produce glossy Class A finishes over fiber reinforcement and foam. At K 2013, Engel showed a combination of RocTool induction heated molds and woven carbon-fiber reinforcement to mold a demo case for an electronic tablet.

The demonstration took pre-pressed carbon-fiber sheets, inserted them into a cavity and over-molded them with high-gloss methyl methacrylate ABS for a glossy piano finish over woven fiber. Ju Teng International Holdings Ltd., Hong Kong (www.juteng.com.hk), recently opened a composite molding plant in China, planned for 100 presses using RocTool induction heated molds to produce cases for electronic tablets and cell phones that combine fiber with thin walls (down to 0.5 mm) and high surface requirements.

RocTool’s induction heated molds are also used to achieve Class A piano black surfaces such as multi-shot molding of an air vent control part for the dashboard of a BMW 320, made by Fischer Automotive Systems GmbH in Horb am Neckar, Germany (www.fischer-automotive-systems.de). The unpainted part combines matt and high gloss surfaces. RocTool induction molds are used with MuCell microcellular foam for the cover of an automotive entertainment system molded by Groupe Plastivaloire, Langeais, France (www.groupe-plastivaloire.com), for Johnson Controls GmbH in Germany (www.johnsoncontrols.com).

Chinese electronics molder Ju Teng International recently opened what will reportedly be the world’s largest composite molding plant for covers for electronic tablets and cell phones. It uses RocTool rapid induction heated molds for Class A surfaces with thin walls and woven fiber.

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Meet the Future!

By Jan H. Schut

Three New Technology Forums at the Society of Plastics Engineers’ ANTEC 2014 technical conference in Las Vegas, April 28-30 (www.4spe.org), focus on cutting edge developments in packaging, medical and 3-D manufacturing areas with applications ranging from outer space to inner body. At each forum a slate of around a half dozen experts in the field present emerging R&D, technical issues, and opportunities for commercialization.

The forum on “Advances in Packaging” is held Monday afternoon April 28. The medical plastics forum on “Plastics in the Hospital and the Human Body” is held Tuesday afternoon, April 29. The forum on “New Frontiers in Additive Manufacturing” is held Wednesday morning, April 30. A complete speaker slate is available at (www.4spe.org/ANTEC-2014-technical-program-information).

‘ADVANCES IN PACKAGING’

Is that your package calling? Bemis Advanced Technology Group, Sheboygan Falls, WI (www.bemisplastics.com) reports on smart packaging designs that give consumers real-time information on how fresh the contents are and whether food products have been properly refrigerated during shipping and storage. Advances in package design can even tell consumers when the contents are real.

New anti-counterfeiting technologies are being invented for drugs and medical packaging, luxury brand products, electronics, and even shipment of original legal documents to make copying difficult. RFID or radio frequency identification devices, known as “source tags,” are also so thin now that they can be invisibly embedded in blister packs, under bottle labels and in garments. When deactivated at checkout counters, source tags notify restocking and inventory.

food packages

RFID “source tags” hidden in labels and packaging combine an integrated circuit and radio frequency antenna. The tag is deactivated when goods are paid for, simultaneously signaling restocking and inventory. Photo: Checkpoint Systems

Dow Chemical Co., Midland, MI (www.dow.com), reports on innovations in light weight films and sheet for longer shelf life and single-serve containers to reduce food waste. Dow also highlights methodology that plastics companies can use to stimulate innovation.

DuPont Co., Wilmington, DE (www.dupont.com), reports recent advances in ionomer technology, including a new ionomer that disperses easily in hot water without solvents, which could be used in fluorine-free grease-barrier coatings on paper and clam shells.

Braskem in Sao Paolo, Brazil (www.braskem.com), reports advances in high melt-strength PP, which are allow more down-gauging and even low density PP foam to lower packaging weight.

New developments in light-weighting also include the scale-up to commercial production of a novel “solid-state” micro-cellular hot drink cup by MicroGreen Inc., Arlington, WA (www.microgreeninc.com). MicroGreen shares the +10-year story of how it developed novel equipment and material technologies to support the new product. MicroGreen’s InCycle cups are made of recycled postconsumer PET.

cup-stacksMicroGreen describes the commercial development of the first solid-state microcellular foamed rPET hot drink cups, including development of novel equipment and material technologies.

‘PLASTICS IN THE HOSPITAL AND THE HUMAN BODY’

Bio-engineering research is creating unique bio-absorbable and tissue-like structures to be implanted in the human body. High-strength PLLA (poly (L-lactic acid) polymer is used in medical implants for its strength and biodegradability. But how does PLLA really biodegrade? A two-year aqueous degradation study at the University of Massachusetts in Lowell (www.uml.edu) on the physical aging and viscoelastic behavior of PLLA finds that specimens degrade from the inside out and can leave highly crystalline residues that don’t degrade. Also new from U. Mass Lowell are biodegradable hollow nanospheres for targeted drug delivery in the body and electrospun silk nanofibers, which have potential for healing wounds and burns.

Micro-electro-mechanical systems, or MEMS, devices are functional systems, miniaturized on a molecular level. They have been used for decades in miniature pressure sensors for medical devices. Now MEMS promise to make devices with more capabilities. From the University of Utah come new helical protein-based nanofibers that are electrically polar in the fiber axis with “high non-linear optical activity and thermally stable piezoelectricity.” That means they have potential for miniature sensors and energy harvesting.

The University of Utah reports new helical protein-based nanofibers that are electrically polar with “high non-linear optical activity and thermally stable piezoelectricity,” so they have potential for energy harvesting and small sensors.

The University of Utah also reports a simple peptide that mimics a triple helical collagen. The peptide can hybridize with collagens in the body and introduce drugs that potentially target pathological tissue, but without toxicity.

Bemis’s MACtac adhesives division in Stow, OH (www.mactac.com), reports new developments in “100% solids” pressure sensitive adhesives for medical products to replace solvent-based adhesives. Solids chemistry is less expensive and complies more readily with regulations on outgassing and chemical migration than solution-based adhesives. Recent advances in polymers and in manufacturing capacity make the new adhesives more available.

‘NEW FRONTIERS IN ADDITIVE (3-D) MANUFACTURING’

Three-D printers are also preparing to go where no 3-D printer ever went before. Last September the National Aeronautics and Space Administration (www.nasa.gov) announced a program to launch a 3-D printer into space to make spare parts on the space station as needed, rather than shipping parts from earth. But a 3-D printer capable of operating in space doesn’t exist, so NASA gave a grant to develop one. It could be ready to fly this year.

Meantime here on earth NASA; the University of Dayton Research Institute in Ohio (www.udri.udayton.edu); PolyOne Corp., Avon Lake, OH (www.polyone.com); rp+m also in Avon Lake (www.rpplusm.com); Stratasys Inc., Eden Prairie, MN (www.stratasys.com); and OEMs are jointly working on additive manufacturing of functional production parts. PolyOne presents the program’s goals, commercialization plans, current results, and successes.

Stratasys’s process, which can combine metals and plastics or different metals in a single part, opens unique possibilities for mold makers of one-piece molds made of different metals, which can’t be achieved by conventional casting.

There are also design issues to consider in layered construction of durable parts. Parts can be built in any plane or in multiple planes. But the choice of plane and how planes join is critical to part strength. Experts will address engineering and design issues for production parts. New material formulations are also being developed, especially high-temperature engineering polymers for low volume production parts. As new materials become available and additive manufacturing equipment gets more robust, new business opportunities are born.

In additive 3-D manufacturing, parts can be built in any plane or in multiple planes. But the choice of planes and how they join is critical for the strength of production parts like this composite bracket for aerospace. Photo: University of Dayton Research Institute

 

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Eco Friendlier

By Jan H. Schut

News at GPEC 2014 (Global Plastics Environmental Conference), coming up on March 12-14 in Orlando, FL, (www.sperecycling.org), by the Environmental Division of the Society of Plastics Engineers, includes a new lignin-rich degradable filler, a process potentially for food-contact PPC, plus new ways to recycle some of the toughest plastic scrap. GPEC runs back-to-back in the same location with the Plastics Recycling Conference 2014, on March 11-12 by Resource Recycling Magazine, Portland, OR, (www.resource-recycling.com), which brings an astonishing 150-plus exhibitors in addition to its program. Here are some highlights.

NEW GREEN MATERIALS

Robert Aldi, adjunct professor of mechanical engineering technology at Rochester Institute of Technology, Rochester, NY, (www.rit.edu) presents “LENS FBM Biomass Waste Stream from Cellulosic Sugar Production Compounded in LDPE.” LENS FBM (lignin-enriched, non-sulfonated fractionated bio-mass) is a new bio-based filler that imparts degradability to plastic film. “Fractionated bio mass” is plant material separated into cellulose, hemicellulose, lignin and other components. The patent-applied-for filler is a fine dark brown powder (down to 5 um) with a slight sweet smell, made from a byproduct of cellulosic sugar, sourced from a Rochester area producer. Cellulosic sugar syrup is refined from cellulose and hemicellulose from wood waste and used for bio-based oils and fuels.

Aldi compounded the FBM filler into masterbatches with LDPE, then molded test samples at different loadings in LDPE. He presents the properties of a compound of 30/70 FBM/LDPE with 2% compatibilizer, which reportedly shows only minimal (2%) loss in ultimate tensile strength. He also presents preliminary test data for 3-layer coex blown film containing the filler. The new filler is being developed by an RIT incubator company, Cedar Creek Products and Technologies, of which Aldi is a co-founder (email: rda9587@rit.edu). Samples of the degradable FBM filler should be available this summer for testing, Aldi says.

Photos courtesy of ALDI

Photos courtesy of ALDI

Bahareh Bahramian, a PhD candidate at the University of Sydney in Australia (sydney.edu.au/engineering/chemical/research/sustainable-technology) presents “Development of an Efficient Process for the Purification of a Renewable Polymer: A Solution for Minimizing Issues in Waste Management.” The reportedly benign process removes zinc catalyst residues from poly (propylene carbonate) to a level that could potentially allow PPC to pass tests for direct food contact. PPC is a biodegradable form of polycarbonate with high oxygen barrier properties, made with alternating CO2 and propylene oxide molecules. If PPC is made with zinc glutarate (or other heavy metal) catalyst, catalyst residues are too high for food contact. U. Sydney’s process reportedly removes more than 80% of zinc residues from PPC to below standard limits. The work is done in collaboration with Cardia Bioplastics in Melbourne, Australia (www.cardiabioplastics.com), which has a subsidiary, CO2 Starch Pty. Ltd., developing degradable blends of PPC and starch. Two U.S. companies also offer PPC, but not as plastic. Empower Materials Inc., New Castle, DE, offers PPC as a niche sacrificial polymer for the electronics industry.  Novomer Inc., Waltham, MA, (www.novomer.com) offers low molecular weight PPC polyols (1000-3000 g/mol) for use in PU foams and adhesives. Novomer, however, touts potential use of higher molecular weight PPC as a barrier layer in food packaging to replace EVOH and nylon, but hasn’t so far done food contact testing. Novomer doesn’t use zinc catalyst and says catalyst residues in its polymers are below 1-2 ppm.

RECLAIMING TOUGH SCRAP

Didem Oner-Deliormanli, research scientist at Dow Chemical Company, Freeport, TX, (www.dow.com), presents “Enhancing the Value of Barrier Film Recycle Stream with Dow’s Novel Compatibilizer Technology.” The patent-applied-for new compatibilizer can combine nylon and EVOH fractions with polyolefins, allowing post-industrial barrier film scrap to be recycled. The compatibilizer, which was announced at last year’s K Show in Germany, uses reactive ultra-high-flow grafted maleic anhydride with a very high melt index of 660. The idea is that this very high flow MAH material breaks EVOH up into smaller particles. The new compatibilizer produces compounds with much smaller domain sizes of nylon and EVOH, better strength and optical properties, Dow reports. Conventional MAH compatibilizers, on the other hand, typically have long polymer chains and very low MIs of only 2-3. Dow is also presenting a paper on “Compatibilization  and Recycling of Post-Industrial Barrier Film Scrap” on the same compatibilizer at the SPE Polyolefins conference in February.

Paul Rothweiler, VP of Technology Development at contract research firm Aspen Research Corp., Maple Grove, MN, (www.aspenresearch.com) presents “Recycled PLA for Retail Applications.”Aspen was the first company to offer post-industrial recycled PLA (poly lactic acid) biopolymer (RPLA001 and RPLA002) two years ago, working with Natureworks LLC, Minnetonka, MN, (www.natureworksllc.com), the major producer of PLA biopolymer. Aspen developed compounds that upgrade industrial PLA trim scrap into new materials, including higher-end alloys and pigmented compounds. PLA scrap is sourced from NatureWorks and includes card stock and form-fill-seal trim, so the material is mostly opaque with some clear. Aspen’s first major commercial application, launched in February, is for colored injection-molding grades of rPLA for egg-shaped containers for chocolates, made for the Eco Eggs division of chocolate wholesaler Maud Borup Inc. Minneapolis, MN (www.ecoeggs.com). Interfacial Solutions LLC (www.interfacialsolutions.com), River Falls, WI, last year also announced its “hyper-branched” post-industrial rPLA at GPEC and won a GPEC Environmental Award. Interfacial Solutions has a National Science Foundation grant to develop the technology, but has not yet licensed it commercially.

EcoEggs

EcoEggs from Maud Borup Inc. use rPLA scrap as a biodegradable source of the traditional plastic Easter egg.
Photo courtesy of EcoEggs/Maud Borup

Among the wealth of exhibitors at the Plastic Recycling Conference, are two unusual new recovery technologies. Environmental Recycling Technologies PLC, Oxford, UK, (www.ertplc.com), acquired the rights to a patented process called Powder Impression Molding, originally developed by US car makers. It’s used to mold thermoplastic parts out of commingled recycled plastic powder.

AMUT s.p.a., Novara, Italy (www.amut.it) has set up a new Ecotech Division to supply sortation equipment to MRFs and PRF’s (plastics recovery facilities), including an “elliptical separator,” consisting of  planks with an elliptical motion that carry light materials like paper and film up and heavy materials down, while sand and gravel fall through. AMUT has five elliptical separators installed in North America, three at PRFs and two at MRFs, with the goal of improving upstream plastic separation.

ballistic 3DSC_0949_Amut

Elliptical separator by AMUT.

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How New Catalysts Are Changing Polypropylene

By Jan H. Schut

Plastics made with genuinely new catalysts are hard to spot when resin companies don’t identify them in data sheets or only make them available to test partners. But several unusual new polypropylenes are in plain sight for the first time at the Polyolefins Conference on “The Polyolefin Renaissance” in Houston, February 23-26, hosted by the South Texas section of the Society of Plastics Engineers (www.spe-stx.org).

They’re made with three “new generation” catalysts. One is an unusual dual metallocene catalyst; the other two are “advanced” or “6th generation” Ziegler-Natta PP catalysts, though that isn’t easy to define. Ziegler-Natta catalyst generations are named for internal electron donors, which control the all-important orientation of monomers as they attach to the polymer chain, i.e. isotacticity and molecular weight distribution. (Generation 4 Ziegler-Natta is diethyl phthalate; generation 5 is diether or succinate.)

“Gen 6” catalysts claim higher activity (which benefits the resin company). They also claim to make PP with more stereo-selectivity, more controlled dispersion of monomers, higher purity, lower VOCs, and lower extractables. Some are also non-phthalate, but phthalate isn’t a clear criterion because “Gen 5” Ziegler-Natta catalysts like LyondellBasell Industries’ (www.lyondellbasell.com) diether or succinate have been non-phthalate for years. Phthalate internal donors are a hot button because of pending European regulations which could make PP with even minute phthalate traces a “controlled substance,” an obvious no-no for spunbonded or meltblown PP fibers for infant diapers. Here are the three “new catalyst” PPs.

FIRST PP COPOLYMERS FROM DOW’S ‘CHAIN-SHUTTLING’ DUAL CATALYST

Gary Marchand, research fellow at Dow Chemical Co. (www.dow.com), presents “PP-Based Olefin Block Copolymers as Compatibilizers for PE and PP.” It’s the first technical report on developmental “Intune” PP-based block copolymers made with Dow’s patent-applied-for CGC or chain-grafting catalyst technology (Patent Applic. # WO2005/090425, 26 and 27). Intune PP copolymers, announced at last year’s K Show in Germany, combine isotactic PP segments with crystalline PE segments (actually ethylene propylene copolymers) or with “PE, polyolefin elastomers and polar materials like EVOH and PA,” Dow says, “for blends and multilayer structures.” Intune PPs aren’t commercial yet, but are being tested as compatiblizers for PP/PE blends.

Dow’s chain-shuttling catalysts, introduced at ANTEC 2006, use two distinct catalysts and diethylzinc as the shuttling mechanism in one or more continuous solution reactor (s), Dow says. One metallocene catalyst produces hard blocks, a second hybrid metallocene catalyst produces soft blocks. Blocks form on the two catalysts, detach from them and park on diethylzinc particles before reattaching to new monomer blocks forming on the catalysts. The length of block segments is controlled by the ratio of diethylzinc to ethylene monomer, with a higher ratio making finer blocks, according to Dow presentations, while the overall hard-to-soft ratio is controlled by the relative amounts of the two catalysts.

Dow previously commercialized Infuse PE-based block copolymers, using its chain-shuttling catalyst technology to combine ethylene and octene monomers. Infuse PE block copolymers, introduced in 2008, allow high temperature and stiffness properties to be tuned independently for the first time. Infuse PE has temperature resistance up to the melting point of PE (about 138 °C) with low Tg. Intune PP could also have temperature resistance up to that of PP (potentially up to 163 °C), but Dow has only reported performance in blends. Dow’s CGC catalyst isn’t available for license.

Science Figure 2

Dow’s first developmental PP copolymers from its unusual “chain-shuttling” catalyst are being tested to compatibilize PP and PE. The “chain-shuttling” catalyst commercially makes PE block copolymers, described as having either linear hard-soft blocks or a comb-like structure.

Dow’s first developmental PP copolymers from its unusual “chain-shuttling” catalyst are being tested to compatibilize PP and PE. The “chain-shuttling” catalyst commercially makes PE block copolymers, described as having either linear hard-soft blocks or a comb-like structure.

PP COPOLYMERS FROM BOREALIS’S SIRIUS ZIEGLER-NATTA CATALYST

When Markus Gahleitner, senior group expert for PP at Borealis Polyolefine GmbH in Linz, Austria (www.borealisgroup.com), presents “A Brief History of High-Impact PP Copolymers,” he includes the most complex materials made so far with catalyst from Borealis’s Sirius emulsion process. These are certain BorSoft impact copolymers for medical films with higher purity, lower extractables, lower emissions, and better retention of mechanical and optical properties in steam sterilization, targeting PVC. They replace existing grades with higher property materials, but aren’t identified in data sheets.

The Sirius process was commercialized in 2006 and introduced at Polyolefins in 2009. Borealis uses it commercially to make advanced Ziegler-Natta catalyst for PP with higher activity and PP properties, but still with a phthalate internal donor (diethylhexyl phthalate). The Sirius process makes solid spherical Ziegler-Natta catalyst particles with magnesium chloride support formed in situ, not separately, for an active site structure that makes PP with relatively narrow MWD. “The replication is different even from other spherical catalysts,” Gahleitner notes. “Purity is higher, molecular weight distribution is slightly narrower, similar to diether catalysts, but with higher isotacticity.” Sirius technology is covered by over 60 patents (including U.S. Pat. # 7465775).

Interestingly, the Sirius emulsion process can also make metallocene catalysts for PP. Because emulsion distributes active sites evenly in round catalyst particles, Sirius metallocene catalysts would make heterogeneous PP copolymers with more uniform and evenly distributed soft domains than previous metallocene catalysts. Borealis invested 100 million Euros in a new semi-works Sirius catalyst production plant in Linz, Austria, which started in 2013, in addition to 50 million Euros for a new Innovation Center in Linz, which opened in 2009 for customer product R&D. Sirius Ziegler-Natta catalyst is also used by Borealis’s Borouge joint venture in Abu Dhabi, United Arab Emirates (www.borouge.com).

Borealis’s new 100-million-Euro catalyst plant started up in 2013, using its Sirius emulsion process commercially to make high activity Ziegler-Natta catalyst for high-purity PPs for medical films. The Sirius emulsion process can also make metallocene catalysts for PP.

Borealis’s new 100-million-Euro catalyst plant started up in 2013, using its Sirius emulsion process commercially to make high activity Ziegler-Natta catalyst for high-purity PPs for medical films. The Sirius emulsion process can also make metallocene catalysts for PP.

PP’S FROM W.R. GRACE’S ‘GEN 6’ CATALYST

John Kaarto, principal research scientist at W.R. Grace & Co., Columbia, MD (www.grace.com), presents “Investigations into Spinning Performance of PP from Developmental Catalysts,” describing fiber grades made from Grace’s non-phthalate Consista C601 catalyst. C601was developed by Dow and introduced in 2011 for Unipol gas phase processes. Dow called it the world’s first “Gen 6” Ziegler-Natta catalyst (substituted phenylene aromatic diester), referenced in some 70 patents (including U.S. Pat. # 8288585, WO # 2010078494, and U.S. Pat. Applic. # 20140012035). Grace licensed non-phthalate technology from Dow in 2011 and offered it as Grace’s HYamPP catalyst for isotactic PP. Then in 2013, Grace bought Dow’s Unipol PP catalyst technology and licensing business, including C601.

W.R. Grace recently bought Dow’s Unipol PP catalyst and licensing business, including non-phthalate “Gen 6”  Ziegler-Natta catalyst (substituted phenylene aromatic diester). Phthalate catalysts are a hot topic because of pending European restrictions on PP with even trace amounts. Schematic:  Patent Applic. WO 2010078494

W.R. Grace recently bought Dow’s Unipol PP catalyst and licensing business, including non-phthalate “Gen 6” Ziegler-Natta catalyst (substituted phenylene aromatic diester). Phthalate catalysts are a hot topic because of pending European restrictions on PP with even trace amounts.
Schematic: Patent Applic. WO 2010078494

The non-phthalate catalyst reportedly makes PP with high isotacticity and broad MWD for a broad PP product line, not just fiber. Grades include homopolymer, random copolymer, impact copolymer and TPO for applications like BOPP, film, pipe, thermoforming, and injection molding including clear articles, Grace says. That’s a lot to make with one catalyst, but C601 can use up to three different external donors to tune products separately, according to Grace publications. Slovnaft a.s. in Bratislava, Slovak Republic, which started up in 2005, makes 100% of its PP production with C601 catalyst for a broad range of products.

C601 reportedly makes standard homopolymers 10%-20% stiffer than Dow’s 4th generation catalyst because of higher isotacticity, allowing down gauging in thermoforming and injection molding. Comonomer distribution is more uniform for better clarity (20% lower haze) in random copolymers. Higher catalyst response to hydrogen also reportedly makes PP impact copolymers with higher melt flow rates and up to 35% lower VOCs. (Hydrogen typically controls molecular weight and increases Ziegler-Natta catalyst activity by three-to-five times, but C601 reportedly requires less hydrogen for higher activity.) C601 has 40%-100% higher activity than Dow’s Gen 4 catalyst, so Grace says it’s cost neutral.

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New Melt Pump Invention Needs No Inlet Pressure

By Jan H. Schut

A new melt pump concept-the first counter-rotating twin-screw melt pump-was introduced at last year’s K Show by Henschel GmbH in Kassel, Germany (www.henschel.de). Melt pumps, which create pressure between a co-rotating twin-screw compounding extruder and die, have previously been either counter-rotating gear pumps or single-screw pumps. Henschel’s Xtreamor pump is like neither. It’s distinguished from conventional melt pumps by dramatically lower inlet pressure and lower energy consumption over the entire compounding line.

It’s an unusual development in a mature product like melt pumps, where new technology for decades has been only incremental tweaks. It’s also unusual coming from Henschel, formerly Henschel Antriebstechnik GmbH, a maker of gear boxes. The inventor of the twin-screw pump, Matthias Henke, was part of a management buyout of Henschel’s gear box business in 2006 and in 2011 became 100% owner. His patent pending pump was under development for two years.

The Xtreamor pump is a mechanical pump or feeding mechanism, which “creates a continuous cylinder like a piston in a car,” explains owner/inventor Henke. After each half rotation of the screws, one chamber between the screws is closed and the next is opened, feeding material forward. Material doesn’t flow backward and pulse, as it does in a gear pump, and fill levels can be higher than with a gear pump.

But the big difference is low inlet pressure. The Xtreamor pump can be fed with inlet pressure of 0 to 0.4 bars vs. 24-50 bars of inlet pressure for standard gear pumps and 2-10 bars of inlet pressure for single-screw melt pumps. The twin-screw pump can generate the same exit pressures as other melt pumps of up to 350 bars.

Abb-Fig 1 HMP140

Henschel’s invention of the first counter-rotating twin-screw melt pump could be a game changer in compounding. The Xtreamor pump is fed with zero inlet pressure from a main twin-screw extruder, reducing energy use for the whole compounding line by up to 50%.

Henschel’s invention of the first counter-rotating twin-screw melt pump could be a game changer in compounding. The Xtreamor pump is fed with zero inlet pressure from a main twin-screw extruder, reducing energy use for the whole compounding line by up to 50%.

A compounder in France runs 100-mm and 140-mm Xtreamor twin-screw melt pumps commercially on twin-screw compounding extruders, making up to 84.5% CaCO3-filled LDPE master batches for film, possibly the highest loading in the world.

Temperatures are also cooler in the twin-screw pump. Outlet temperature coming from the main extruder remained at 233 C for CaCO3-filled PE vs. an increase to 244 C for a gear pump and to 252 C for a single-screw melt pump, Henschel reported at the K Show. The Xtreamor pump has electric heating cartridges and water injection barrel cooling. (Gear pumps typically don’t have heating or cooling, though they can, while single-screw melt pumps typically do.)

Don’t  confuse the Xtreamor pump with a counter-rotating twin-screw extruder either. Besides having two counter-rotating screws, there is little similarity. Screws in Henschel’s melt pump have outside/inside diameter ratios of two or higher where screws in counter-rotating twin-screw extruders have OD/ID ratios of 1.45 to 1.85. The twin-screw pump has L/Ds of only 2.3-2.5, where counter-rotating twin-screw extruders have ten times higher L/Ds of 22-32 or more.

Henschel has designed five different screw geometries so far with different depth/diameter ratios and number of screw flights and offers pumps from 60 to 200 mm diameter. The twin-screw melt pump also requires a different gearbox than Henschel has built before. Henschel set up a new unit, Henschel ExtruTec GmbH in Heiligenstadt, Germany (www.xtreamor.com), to build the new pump and plans to have labs set up for customer trials in both Germany and the U.S. later this year. Siegward Rockstedt, former head of Maschinenfabrik S. Rockstedt GmbH in Germany, which built multi-screw compounders, worked with Henschel on the first trials and installations.

The first two Xtreamor melt pumps are in commercial use at compounder JM Polymers in Saint-Romain-Lachalm, France (www.jmpolymers.fr), which has had a 100-mm-diameter Xtreamor melt pump running for a year and a 140-mm melt pump for seven months. Both are on twin-screw extruders compounding CaCO3-filled LDPE master batches for film. JM Polymer’s website offers Cacolin PE master batches with up to 82% CaCO3, one of the highest reported commercial loadings. JM has also made custom formulations for customers with up to 84.5% CaCO3, believed to be the highest in the world. Heritage Plastics Inc., Picayune, Miss. (www.heritage-plastics.com), offers PE master batches with up to 80% CaCO3 and has gone higher for custom formulations.

With operating experience, JM confirms that lower inlet pressure in the twin-screw pump results in dramatic overall energy savings on the main extruder of more than 50%. “Because the upstream co-rotating twin-screw extruder doesn’t have to generate high fill pressures, it allows more of the compounder to be used for mixing, and power consumption is crazily low,” reports Pierre Burdier, technical engineer at JM Technology, which builds JM’s compounding machinery. “The Henschel pump is only 38 kW where a comparable single-screw pump is 110 kW. ROI on the new melt pump was less than a year on the energy savings,” JM’s Burdier notes. “Torque on the main extruder is also 20% less because it doesn’t have to push, only to mix.”

OTHER NEW MELT PUMP TECHNOLOGIES

Two other new melt pump developments also target energy savings and improved flow. At the K Show, Maag Pump Systems in Oberglatt, Switzerland (www.maag.com), part of Dover Pump Solutions Group, introduced a new generation counter-rotating gear pump on which Maag worked for eight years. Generation 6 represents a redesign of every element of the pumps, the company says, “with more compact design, sharply increased volumetric efficiency, and lower pulsation.” It allows up to 50% higher flow rates for the same pump size with half as much material recirculating in the pump, Maag says. The first is in commercial operation.

Nordson Xaloy Inc., New Castle, PA (www.xaloy.com) since 2009 has offered a flexible system of modular bushing inserts on its standard and high pressure gear pumps to optimize flow properties for different polymers. Xaloy has built eight insert variations so far. A specific size pump can have multiple bushing inserts, which can easily be changed, the company says. Flow bore inserts are typically used for thermally sensitive polymers like PC, ePET, and biopolymers.

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