Plastics News senior reporter Bill Bregar and reporter Rhoda Miel filed these items from Plastics Encounter and the Society of Plastics Engineers' Antec conference, held 5-7 in Milwaukee.
GITBlow connects molding processes
Martin Schäfers, a doctoral student at the Institute of Polymer Technology at the University of Paderborn, Germany, described the GITBlow process, which combines aspects of gas-assisted injection molding and blow molding.
Actually, GITBlow uses two gas-injection steps, the first to make a hollow section, and the second to expand that hollow section even more. The finished parts have thin walls and extremely large hollow areas — so GITBlow competes favorably with water-assisted injection molding and extrusion blow molding, Schäfers said.
Applications include conduit for automotive fluids, air conditioning ducts and intake manifolds. For appliances, the process can make conduits and ducts for air and water, and other hollow parts.
The first step is making what Schäfers called a preform by using gas-assisted molding with nitrogen gas. To finish the part, a core pull is moved, and gas is pumped in again.
Researchers in Paderborn molded parts on an Arburg press with 120 metric tons of clamping force to run the trials. They tested two methods, a one-stage process and a two-stage process.
One-stage GITBlow does both gas-injection steps in the same station, in a closed mold. For the two-stage method, the preform is made in one station, then is moved to another mold, then reheated for the second shot of gas.
Two-stage GITBlow requires a rotating mold and a handling unit for the radiant heater, so it's more expensive. But it has several advantages. Selective heating of the area to be inflated the second time means that no areas that have already cooled get stretched. Also, the gas-conveying zone of the preform and the finished part can have different external contours, providing for more freedom of design. Finally, the preform and part are molded at the same time on the rotating mold, cutting the cycle time.
Parkinson site used to test biomaterials
BioSolar Inc., which has developed solar power cells using plant material, did its development and testing at a Marshall and Williams laboratory for making biaxially oriented film in Woonsocket, R.I.
Santa Clarita, Calif.-based BioSolar contacted Parkinson Technologies Inc., which makes Marshall and Williams orientation equipment, known as tenter frames. Product trials included running films of different materials. The goal was to use biaxial orientation to add strength to bio-based materials.
The pilot lab has a complete inline system for coextruding film and sheet with as many as five layers, with either machine direction orientation or transverse direction orientation.
New hot-runner parts made to mold PLA
With bioresins getting more attention, D-M-E Co. has rolled out its Eco-Smart line of hot-runner components designed to process corn-based polylactic acid.
``It's new ground for a lot of the industry, but there are more and more companies getting interested in PLA,'' said Robert Starr, director of global marketing.
Molders need hot runners with greater corrosion resistance and a better ability to minimize shear heat because of PLA's temperature sensitivity, he said.
Madison Heights, Mich.-based D-M-E worked with molders for two years to fine-tune the materials and parts in hot runners to work specifically with the resin.
Paper explains use of magnetic fillers
By adding magnetic fillers to polymers, polymer-bonded magnets can be injection molded with a multipolar structure, according to a paper by Stefan Eimeke, a researcher at the Institute of Polymer Technology at the University of Erlangen-Nuremberg in Erlangen, Germany.
For making magnets, injection molding has several advantages over traditional sintering techniques, such as better dimensional stability, more freedom to design complex shapes and cost reduction in the one-step process, Eimeke's paper said.
The key is the use of permanent magnets incorporated inside the mold to both orient and magnetize the metal fillers inside the melt. The orientation changes from pole to pole, based on the placement of the in-mold permanent magnets, he said.
Institute of Polymer Technology researchers studied how several variables affect the orientation, including changes in melt temperature, viscosity, part thickness, flow length and the type of steel used. One conclusion: the magnetic conductivity of the permanent magnets is stronger on thin parts than thicker parts.
Researcher studies composite fuel cells
Chia Yen Tzeng, a research assistant at Chung Yuan Christian University in Taiwan, described studies into fuel-cell plates made from polyphenylene sulfide filled with 50 percent carbon fiber.
Tzeng said filled composite fuel-cell plates have desirable mechanical and chemical properties, but they have poor conductivity required for that appli- cation. Using a JSW injection press, the researchers molded bipolar plates using standard injection molding and injection/ compression molding. The goal was to get low through-plane resistance. One of the study's conclusions was that the injection/ compression process can improve conductivity by improving carbon-fiber orientation.
Plastics News senior reporter Bill Bregar filed this report from the Plastics Encounter show, May 5-7, which was held with the Society of Plastics Engineers' Antec conference in Milwaukee.
RTP trumpets TPEs' good bonding ablity
Winona, Minn.-based compounder RTP Co. used the Plastics Encounter show at Antec to introduce a family of bondable thermoplastic elastomer materials, called the RTP 6042 Series, for use in combination with a wide range of rigid plastic substrates.
RTP has formulated standard grades to bond to polycarbonate, ABS, PC/ABS, PC/polymethyl methacrylate and thermoplastic polyurethane.
Products in the new RTP 6042 Series have a wider processing window than the RTP 6002 Series, which they replace, the company said. Additional improvements include superior bonding performance and more consistent mechanical properties.
``The critical element in any overmolding process is the chemical bond between the soft elastomeric material and the rigid substrate,'' said Paul Killian, technical marketing manager for RTP's TPE Division.
The materials are especially good for rugged electronic devices that need excellent tensile and tear strength, plus abrasion resistance, according to Killian.
The 6042 Series materials are special alloys, but RTP is not releasing what type of TPEs are involved.
In other news, RTP has entered into a trademark agreement with Solvay Advanced Polymers LLC. Under the deal, RTP will compound and market pre-colored Radel R polyphenylsulfone and Udel polysulfone resins globally, using Solvay trademarks.
The agreement means customers that want small and mid-sized lots of pre-colored Radel R and Udel compounds can get them quickly from RTP.
Milacron introduces new barrel heater
Milacron Inc. of Cincinnati is now selling a radiant barrel heater made from ceramic fiber insulation, through its ServTek parts and service unit.
ServTek TCS is an improvement over standard heater bands for precise, highly energy-efficient heating and cooling of barrels for injection and blow molding machines and extruders. The TCS stands for temperature control system.
ServTek TCS is available as an option on new Milacron-brand machinery or as a retrofit on any company's equipment.
Milacron is pitching the barrel heating and cooling system under its ``earth-friendly technology'' portfolio. In many states — including Wisconsin, where Plastics Encounter was held — utilities offer rebates for using the ceramic radiant barrel heaters because they consume less electricity than heater bands, the company said.
Ritch Waterfield, ServTek product manager, said ServTek TCS can result in 30-50 percent energy savings, with as short as an 18-month payback time.
A series of radiant heating elements totally encapsulates the barrel. In radiant heat, all of the heat goes directly into the barrel. The heat stays there, reducing burns to workers, since the outside of the insulated barrel is cool to the touch.
Heating sections, strapped together by Velcro, can be easily removed and replaced. Wires of the heating element run inside the ceramic fiber-shaped sections. It controls the temperature along the entire length of the barrel.
Also, ServTek TCS cools the barrel back down faster, by drawing air directly across the barrel.
REX Materials Inc. of Fowlerville, Mich., manufactures the heaters to the specifications of Milacron, which will offer the technology in the Americas.
REX is a longtime maker of ceramic fiber heaters for applications such as water heaters, boilers, furnaces, die-casting and molten metals manufacturing.
REX got into the plastics machinery market several years ago, when it licensed the concept from Insul-Vest Inc. of Tulsa, Okla., which makes insulating blankets to go over heater bands.
But in the plastics industry, REX was not a household name. Milacron is, and the Cincinnati-based plastics machinery manufacturer plans to promote the technology aggressively.
Wittmann's Drymax ready for bioresins
Wittmann Inc. of Torrington, Conn., rolled out its Drymax twin-bed desiccant dryers, now designated as ``bioresin ready'' — able to dry a full range of bioresins on the market today.
According to the company, several standard features make the Drymax line well-suited for the plant-based materials, especially their ability to maintain constant, low-temperature operation, down to 120° F, with no temperate spikes, and a constant low dew point.
Constant air flow optimizes drying times. A feature called SmartRegen monitors the drying process of the desiccant beds, reducing the amount of energy needed to regenerate the desiccant.
In related news, Wittmann has developed a standardized rating method and a comprehensive testing program for each of its Drymax dryers.
PT linking databases from US & Germany
Plastics Technology magazine announced a materials selection database, Plaspec Global, that links up PT's North American database with the Campus database from M-Base Engineering + Software GmbH in Aachen, Germany.
Plaspec Global is available in basic and complete versions.
The basic version is free, and allows users to search and retrieve single-point and multiple-point data for materials by supplier name, resin type/grade, melt flow properties, flex modulus, flammability and process type, and also browse technical literature.
The complete version offers advanced features, so users can search on all properties, perform direct comparisons of materials on both single- and multiple-point data, product analytical tables and charts, search case studies on applications such as packaging, medical, automotive and electronics.
The introductory price for a full-year subscription costs $99.
Plastics Technology demonstrated Plaspec Global at Plastics Encounter.
Plaspec began in 1984, when the magazine launched it as a telephone dial-up subscription service. In 1997, Plaspec moved to the Internet. Plastics Technology took the database in-house in 2000, putting it on its Web site.
Tricia Karsay, PT's director of marketing, was named product manager for Plaspec Global. PT is published by Gardner Publications Inc. of Cincinnati.
Admet Inc. presents testing equipment
Admet Inc. of Norwood, Mass., displayed its testing equipment for polymers and films, including two control products.
Admet said its eP digital controller and the Precise digital controller offer accurate test programming and control, and convenient collection of test results. The data can be moved to spreadsheets and reporting software.
The company's MTestWindows is a personal-computer-based materials testing system. The AdmetQuattro testing system adds cyclic testing programming, as well as control.
Farrel extruder works well for small runs
Farrel Corp. said its new CP125, the latest model of its CP Series II, was developed for small-scale compounding in a laboratory, a pilot plant or limited production.
Its throughput rate is between 176-330 pounds an hour.
Farrel said the CP125 is good at running polyolefin-based compounds with high levels of mineral fillers, additives and color masterbatches; polymer-rubber blends; and applications that need high-intensity mixing at a low processing temperature.
The twin-screw extruder has counterrotating, nonintermeshing rotors, which Farrel said allows for fast color changes. The CP125 comes standard with a single-stage extruder. A two-stage vented barrel also is available.
Ansonia, Conn.-based Farrel recently installed a CP125 in its laboratory in Rochdale, England. Customers can test their specific materials on the line, which includes gravimetric feeders for metering test materials to the continuous mixer and extruder. The line can be fitted with either a strand die or an underwater pelletizing system.
After 20-year search, List AG finds answer
After more than 20 years of research, List AG of Arisdorf, Switzerland, has realized its goal of solving the puzzle of direct evaporation for temperature-sensitive polymers.
List's two-step process has moved from concept to pilot scale and now is being scaled to commercial production for several manufacturers.
Direct evaporation, also known as direct devolatization, was recognized as an energy-efficient alternative to the traditional stripping method, according to List. But the process had a major drawback, since it only worked on polymer solutions that were not temperature sensitive.
List claims it has solved that problem. List engineers have discovered how to maximize the mass-transfer driving force for evaporation. During the first step, about 99 percent of the solvent evaporates under atmospheric pressure, or a slight vacuum, and is condensed and recovered. In the second step, any residual volatile concentrations are reduced to a final specification.
List recently demonstrated the new technology to about 60 invited engineers at a Fraunhofer-Gesellschaft pilot plant in Schkopau, Germany. The pilot plant is a joint project between the Fraunhofer Institute for Applied Polymer Research and Fraunhofer Institute for Mechanics of Materials.
List USA Inc. is based in Charlotte, N.C.
During Antec, engineers from List presented two papers about the company's research into kneader reactors:
* Daniel Witte introduced his paper on ``Advanced Process Design in High-Volume Kneader Reactors Using Multiple Feed Ports to Avoid Crust Forming, Foaming and Low-Heat Transfer.''
* Boyd Safrit gave a paper on ``Kneader Technology for the Direct Devolatization of Temperature-Sensitive Elastomers.''