K 2004: Oktoberfest of polymers

K2004, the world's largest trade fair for plastics and rubber technologies (konline.de), is set for October 20 to 27 in Dsseldorf, Germany. Nearly 2,900 exhibitors from 53 countries will showcase raw materials, engineered parts, and reinforced plastics, as well as production machinery and related equipment.

The show, held every three years, will feature over 1.7 million sq ft of exhibit space in 17 halls and is expected to host about 220,000 visitors. It offers a unique, one-stop opportunity to see a wide array of technical innovations from large and small companies alike, as well as the latest automotive, packaging, electronics, medical, and aerospace designs.

MATERIAL ADVANCES
DuPont, Wilmington, Del., invests about $1.2 billion a year in R&D, with about one-third of its sales generated by products introduced in the last five years, according to Nandan Rao, global technology director of the Engineering Polymers unit. The company will highlight a number of recent developments at K 2004, including:

Functional aesthetics. DuPont has developed an array of paintable and chrome-plateable products including Delrin polyacetal, a previously difficultto-decorate resin because it has a naturally shiny, lubricated surface. Applications include cosmetic packaging, sporting goods, medical appliances, and buckles for apparel.

A new plateable grade of Zytel HTN economically replaces plated metal in high-temperature applications requiring dimensional stability. Potential uses include knobs and trim on appliances, underhood car parts, and wheel covers subject to heat from brakes.

Under development, Shine-E Rynite combines high surface gloss with the high-temperature and structural properties of reinforced PET thermoplastic polyester. Painted automotive panels in this new resin would weigh less than equivalent metal parts.

The mirrorlike surface of unpainted parts also opens up other promising applications, including domestic electric-appliance parts which are exposed to heat, such as oven door handles, toaster casings, and motor housings. Electrically conductive versions of the resin are also in the works.

Conductive polymers. The use of conductive carbon fibers and fine graphite in plastics is not new, but optimized dispersion of the additives has improved conductive properties without degrading physical performance.

Conductive Zytel CDV and a range of conductive Delrin acetals are for components such as fuel-tank caps and fuel-line connectors. The static-dissipating materials help avoid the danger of spark-induced explosions. Nonautomotive applications include business machines, computer peripherals, electronic devices, medical equipment, and EMI shielding.

ETPV. New engineering thermo plastic vulcanizates, or ETPV, resist oil, grease, and chemicals from 40 to 160°C. ETPV can be injection molded, blow molded, extruded, and bicomponent molded on standard thermoplasticprocessing equipment. Two grades, 60 and 90 Shore A, are available in standard (1,000 hr at 150°C) and heat-stabilized (3,000 hr at 150°C) versions.

The material requires no compounding or postcuring, does not age like rubber, and is readily recyclable. Commercial uses include automotive spark-plug boots and air-brake hoses. Other promising applications include ducts, ignition seals, and inboard CV-joint boots.

21ST CENTURY TRENDS

"K is the ideal platform for exchanging technical information," says Jrgen Kulpe, spokesman for Ticona GmbH, Kelsterbach, Germany. "This is where our polymer know-how cross-fertilizes with that of processor and supplier expertise to generate product ideas for tomorrow." To stimulate forward thinking, visionary concept studies from Frankfurt product designer Olaf Barski will be featured at Ticona's K 2004 booth, including an innovative washing machine with three drums and a bathroom unit that serves as a shower, bathtub, and sauna. Ticona will also host Matthias Horx from the Future Institute (Zukunftsinstitut) who will provide insights into tomorrow's world and identify the 21 ^st century mega-trends including:

Automobile construction. Global demand for engineering plastics in applications such as mechatronic systems, turbocharger components, and fuel cells are a few examples where Ticona is developing new applications and process technologies. For example, together with machinery maker SIG Kautex in Bonn, Germany, Ticona has developed Fortron 1115L0, a polyphenylene sulfide blowmolding grade. This glass-fiberreinforced plastic lets turbocharger air pipes be made in a single operation, replacing a complex design consisting of aluminum pipes and fluoroelastomer tubes.

Engineering thermoplastics are also building bipolar plates for fuel cells previously made from gold-coated stainless steel, aluminum, graphite, and thermoset/graphite blends. Injection molding produces bipolar plates faster without the need for costly secondary machining operations. Engineering polymers improve long-term fuel-cell performance. Vectra LCP (liquid-crystal polymer) and Fortron PPS (polyphenylene sulfide), for instance, withstand aggressive media in fuel cells, resist corrosion, and remain dimensionally stable to 240°C. Hostaform acetal copolymer serves in fuel-cell peripherals such as pumps and compressors. Structural automotive components are also good prospects for high-tech plastics. Examples include BMW front roof frames and rain channels made from long-fiber-reinforced Celstran PP-GF50, as well as the roof edges and hook guides made from Hostaform C 9021. From the VW Golf 5 and Opel Astra, Ticona plastics are found in the front roof frame (long-glass-fiber-reinforced Celanex 3300-2), draft deflector and rain channel ( Celstran PP-GF50), and hook guide (Hostaform C 9021 M).

Electronics and computers. Vectra LCP's good flow and mechanical properties, high resistance to temperature extremes, and tight tolerances make it particularly suitable for manufacturing electronic components and cell-phone parts. Molded Interconnected Device (MID) technology is a new process for K 2004. It uses laser-direct structuring to produce 3D circuit boards with extremely fine conductor tracks from a new Vectra LCP grade.

Another example is Topas COC, a lightweight, high-transparency cyclic olefin copolymer that's ideally suited for display components and light-guide panels (LGP) for flat screens. Along with high optical requirements, LGPs demand accurate reproduction of detail — Topas offers good flowability and long-term dimensional stability.

Medical. Vectra's good flow properties also let designers produce extremely fine features to more easily miniaturize medical devices while another high-performance medical plastic, GUR (ultrahigh-molecular-weight polyethylene), serves as an efficient additive in paints, coatings, rubber, and seals, as well as a structural element in carbon block microfilters. Ticona's successes with GUR in medical has spurred the development of four medical technology polymers including Hostaform MT, Celanex MT, Fortron MT, and Vectra. These materials are biocompatible, have high resistance to chemicals and disinfectants, and possess first-rate mechanicalproperties. Topas COC also is a medical-grade polymer serving as a glass replacement in disposable syringes. Outstanding barrier properties make it suitable for blister packs.

PRECISION MOLDING

Engel Austria GmbH, Schwertberg, Austria, will highlight the latest developments in multicomponent injectionmolding machines and the production of high-precision parts.

The company's Watermelt process permits injection molding of hollow parts, even in cases that require complex multipoint injection. According to Georg Steinbichler, senior vice president of R&D, advantages of water-injection technology (WIT) over gas injection for molding hollow parts include 40 to 70% shorter cycle times, more uniform wall thicknesses, and smoother inner walls. WIT is particularly suited for pipes, manifolds, and other parts featuring large-diameter passages or channels.

The company has refined the process controls and mold design, optimized the water nozzle and injector geometries, and adapted the technology for multipoint injection and multicavity molds. Making it work involves precise coordination of process sequences. After complete displacement of the melt, the hollow profiles are flushed continuously with water to cool the part. Residual water is then forced out with compressed air and the insides of the profiles blown dry.

At K 2004, the company will demonstrate a complex, multicavity application. Four sides of a large, collapsible fruit crate 600 x 400 x 250 mm with hollow, stiffening profiles will be molded through water injection along three of the edges. Watermelt is used in conjunction with full-shot process, the displacement of the melt core into spillover cavities.

X-Melt is another new processing technology developed by Engel for economical, high-speed injection molding of thin-wall and microprecision parts. The energy for rapid injection is stored in the melt, which is precompressed in the space in front of the screw or, more recently, in the hot-runner system. This eliminates the need for a separate hydraulic-accumulator normally required for injection. The mold cavity fills in fractions of a second through the abrupt, explosionlike expansion of the precompressed melt when the needlevalve nozzle opens. X-Melt improves reproducibility and this, in turn, increases precision, especially in the case of small parts.

Typical shot weights range from 0.1 to 40 gm, wall thicknesses from 0.1 to 0.8 mm, and flow length/wall thickness ratios as high as 400:1. X-Melt is suitable for engineering thermoplastics, including PC, PBT, LCP, PA, POM, and ABSPC blends.

Engel will demonstrate X-Melt's precision injection-molding capabilities on an all-electric E-Motion 200/55 machine with a four-cavity mold. Production involves a cell-phone battery case with a wall thickness of only 0.15 mm and a cycle time of about 5 sec, including demolding. Generating such complex microprecision parts would be impossible on conventional injectionmolding machines, says Steinbichler.

BIGGER WINDOWS

Plastic windows are a growing trend in the automotive arena. They are less apt to break and splinter, weigh 40% less than glass, offer more design freedom, and cost less. Small plastic windows are already standard equipment in passenger cars. But economical large windshields from plastics have been, up to now, beyond car manufacturers' reach.

In Dsseldorf, Battenfeld Injection Molding Technology, Meinerzhagen, Germany, along with Summerer Technologies and Exatec, will show the cost-efficient production of large car windows from polycarbonate using the IMPmore (In-Mold-Pressing) injectioncompression process.

Plastic car windows must be virtually tension-free to ensure weathering resistance and permit effective antiscratch coating. Injection-compression, a lowpressure injection-molding process, is a proven method for making almost tension-free parts.

The windows will be produced on a Battenfeld HM 20000/19000 injectionmolding machine with a two-platen module. A special folding mechanism in the mold opens a wedge-shaped embossing gap, optimizing pressure buildup and in-mold pressure distribution during the injection and compression phases. Even in the case of the large 1,050 mm ² windscreen with a 4-mm wall thickness, IMPmore keeps in-mold pressure evenly balanced and below 200 bar across the entire molded part.

The machine's servohydraulic system has been specially developed for the IMPmore process, and for manufacturing large windscreens. It supplies balancing cylinders located near the top and the bottom of the mold — areas subject to strongly asymmetric pressure from injection near the edge of the molded part and the folding mechanism. The balancing system maintains a uniform load on all four tie-bars and has a direct effect on the compression process. A generously dimensioned mold space and the two-platen module ease mold insertion and removal of bulky parts, a must in the production of large car windows.

EQUIPMENT INNOVATIONS

At K 2004 Krauss-Maffei, Munich, Germany, will display a new MX clamping unit in combination with a twinscrew extruder and injection-molding compounder (IMC). The clamping unit shifts the locking and clamping force build-up to the moving side, reduces the dry-cycle time by more than 30%, and improves access to the fixed platen and nozzle area.

The single-piece moving platen evenly distributes clamping force, resulting in lower mold deflection and longer mold service life. Thanks to the modular design of the MX-range, the clamping unit can be combined with a twin-screw extruder, thus creating an IMC.

IMC-technology makes it possible to compound various raw materials (blends) in a single process. It can also mold reinforcements (additives, fillers, and fibers). The twin-screw extruder is directly integrated into the injectionmolding process. Initially, material is melted in the twin-screw extruder and mixed with glass fibers or fillers. At high plasticizing rates, it's possible to compound the materials "to order" during the injection cycle. The melt is routed via a buffer-store into a shot-pot injection unit. From there the material injects into the mold.

Processing to order makes purchasing separate raw materials more cost effective for the processor compared to ready-made compounds. IMC is particularly gentle to the material being processed so high filler loadings are possible and long fibers can be introduced into the structural component without damage. A KM 950-14000 MX/IMC will be shown producing a long glass-fiber-reinforced automotive part.

Krauss-Maffei is the first company to successfully combine injection molding and reaction-technology with the processing of thermoplastics and polyurethane into a single multicomponent system. At K 2004 a manufacturing cell will be displayed, in which an injection-molding machine KM 160-750 CX is linked to a compact PUR-mixing and metering machine. During the Exhibition, the cover of a seatbelt buckle lock employed in a luxuryclass car will be molded.

The buckle perform is a thermoplasticthat's encapsulated in PUR. PUR gives the belt excellent surface qualities, which reportedly can't be reproduced with conventional thermoplastic elastomers. At the show, removal of the buckle and layered stacking into transport containers is carried out by a Krauss-Maffei linear robot 160 NR. The operation of the robot as well as control and power electronics are fully integrated into the injection-molding machine. The space-saving, operatorfriendly, and efficient linear system increases productivity through short mold strokes and times. Krauss-Maffei will also feature C3 Sprinter machines at K 2004 with two manufacturing examples. One will show how a KM 600-3500 C3, employing a stack-mold, runs at extremely short cycle times while molding 550-ml food-packaging containers. The second example on display will be the first time the C3 range is employed for a multicomponent 400-ml container.

A clean-room KM 35-90 CX machine for medical will also mold germ-free class A to FDA-GMP pipettes in a 20-impression mold. Here, only the compact, self-supporting clamping unit of the KM 35-90 CS protrudes into the clean room. The clamping unit can be retracted from the clean room for mold changing or maintenance work.

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Composite recycling

Plastic-packaging recycling is an ongoing business in many parts of the world. There has been little similar action in the automotive field, but regulatory pressures will soon change that, says DuPont's Nandon Rao. The European Commission has issued an end-of-life vehicle directive requiring that all cars sold in the EU after 2005 must be 85% recyclable, and 95% by 2015.

DuPont has developed nylon-composite recycling technology to help the automotive industry meet these targets. The process takes used parts of glass-reinforced or mineral-reinforced nylon and delivers new ones equivalent to those made of virgin material.

Together with Denso Corp. of Japan, DuPont investigated the feasibility of recycling scrap radiator end tanks made of glass-reinforced nylon 66. The material, degraded by years of contact with hot engine coolant, was ground up and fed into a prototype reactor. The process dissolves the polymer, filters out glass fibers and contaminants, then precipitates, dries, and rebuilds the polymer, producing like-new nylon 66. It is then compounded with glass fiber and molded into new end tanks.

Key mechanical properties — strength, stiffness, and impact strength — equal those of virgin nylon parts. Molding characteristics and resistance to aggressive liquid coolants yield similar results. High-temperature creep, high-pressure cycling, vibration, and lowtemperature impact results are similar to those of tanks made from virgin materials, and exceed requirements of Denso's automotive customers. The company has had similar success with nylon 6 composites.

Better bonding

In the past, it was difficult to chemically bond dissimilar plastics. Overmolding or welding different polymers often means a limited choice of materials and poor joint strength. For instance, overmolding a softtouch surface to a rigid engineering polymer usually limits elastomer choices to one or two hardness levels. And poor bond strength can lead to delamination.

A new process from DuPont strongly bonds most any plastic by bringing the two surfaces together in a molten state. Structural-bonding technology produces a specially developed microporous tie layer, which results in strong physical anchoring between the two materials. Early applications include soft-touch components made by overmolding or two-component molding, and the welding of polyacetal components to the surface of polyethylene fuel tanks.

Aerospace composites

Lightweight composites based on Ticona's Fortron PPS are used in the wings of the Airbus A 380 — the largest ever designed for a passenger aircraft. The wing leading-edge nose, measuring 23 25 m, is made from the fiber-reinforced PPS laminate, Cetex, from Ten Cate, Holland.

Dutch aircraft builder, Stork Fokker AESP B.V., uses the PPS composites in the new J-nose which is more aerodynamic than its D-nose aluminum predecessor and houses electric cables, deicing equipment, and other systems. Structural components made from PPS composites are up to 50% lighter than their metal counterparts.