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Novel tamper-evident thermoformed packages with a pull-open tab have been adopted by Sara Lee and Wal-Mart for single-serve applications. They’re formed in PET by PWP Industries.
New supplier Octal will become the world’s leading APET sheet producer and wants to make it more attractive to thermoformers by delivering a tighter gauge tolerance of ±1%.
Scratch- and mar-resistant TPO/acrylic sheet is held together with a new non-olefin tie layer called Addhere 228 from Solvay Engineered Polymers.
The industry’s largest twin-sheet thermoformer and the first North American source of halogen heaters were among the machinery and equipment developments at the recent 17th Annual SPE Thermoforming Conference in Cincinnati. There was also plenty of news in materials, including a new tie-layer resin that bonds acrylic to TPO, the emergence of cyclic olefin copolymers (COCs) as modifiers for thermoformed polyolefins, and a new supplier of APET with ambitious plans to become the industry’s leading producer.
Twin-sheet gets bigger
Twin-sheet thermoforming is said to be gaining momentum in ever-larger parts as a replacement for metal and fiberglass-reinforced plastics (FRP). This has resulted in an increased demand for larger machines with more cavitation and greater productivity, according to Michael Alongi, sales manager for Maac Corp. The company recently delivered a four-station rotary twin-sheet pressure former with a 21 x 8 ft mold area to an undisclosed manufacturer of paddle boats and kayaks. Until now, the largest twin-sheet machines have been in the 12 x 8 ft range for pallet manufacturing, according to Alongi. He says the Model 218R4DPT sets another new benchmark for twin-sheet because it can produce parts up to 65 in. deep. Bigger twin-sheet units are possible because of the availability of larger motors and a redesigned machine structure that withstands more pressure across a larger surface, Alongi explains.
The 60-ft-diam. rotary features a 50,000-lb moveable platen, two 75-hp motors, and dual quartz-heated ovens. Articulating clamp frames adjust to the shape of the mold so there is less sheet stretching and thinner, more consistent part walls. The machine runs heavy-gauge sheet up to 0.5 in thick in a cycle time of 1 to 4 min.
Maac also delivered another large twin-sheet machine for production of heavy-truck hoods and bumpers made of ABS and TPO. The Model 168R3PT is a three-station rotary pressure former with a 16 x 8 ft mold capacity.
Halogen heater source
Modern Machinery has become the first North American manufacturer of halogen heating systems. Up to now, the best-known supplier of halogen heaters has been Germany’s Geiss AG. Modern Machinery introduced tungsten-tube halogen oven heaters that use off-the-shelf controls and electrical hardware. The heating elements come from Weco International.
The new halogen heaters feature a new “burst-fire” control system instead of the usual 2-sec on/off cycling. With the rapid-fire “burst” system, the elements cycle continuously and reportedly deliver more consistent and even heating.
Acrylic bonds to TPO
In material advances, Solvay Engineered Polymers announced a proprietary non-olefinic tie-layer resin that bonds acrylic to TPO. The result is a high-gloss, scratch- and mar-resistant acrylic surface over the tough TPO layer, a combination that could be useful for agricultural equipment, recreational vehicles, and marine and construction uses. Previously, there was no available tie layer to adhere the two materials in-line, while off-line lamination has the disadvantage of higher cost, according to Eric Short, Solvay business-unit manager.
Solvay’s Addhere 228 tie-layer resin is available in pellet form and can be used in tri-extrusion of the TPO substrate, the tie layer, and the acrylic. In addition, the process also allows for direct in-line lamination of acrylic film. Typically, Addhere is coextruded in a 4- to 6-mil layer between TPO and acrylic. TPO thicknesses are 0.110 to 0.187 in. while the acrylic is 0.006 to 0.007 in.
The sheet boasts better melt strength than high-gloss TPO, but with no sacrifice of physical properties, Solvay claims. Reground sheet containing up to 20% scrap is claimed to have virgin-like properties. The material is currently being sampled, and the first commercial use is expected in decorative panels.
New heavyweight in APET
The SPE meeting was abuzz with the news that Octal Holding Co. of Oman plans to build a 660-million-lb/yr integrated PET resin and APET sheet plant in Oman. Slated for start-up next May, the facility would be the first of its kind and make Octal the world’s leading producer of APET sheet. Worldwide demand for APET in clear rigid packaging is growing 10% to 12%/yr, according to William Barenberg, chief operating officer at Octal’s U.S. office.
APET has better clarity and gloss than PVC and is less brittle than OPS. But cost has limited APET’s use. Barenberg believes the company’s focus on product consistency and higher productivity will improve the economics of APET and encourage new applications. “We want to do for APET in thermoforming what the resin guys did for PET in bottles,” asserts Barenberg. Applications include trays for fresh foods and dairy products and packaging for consumer items like toys and electronics. Penetration is also being made in cold-drink cups.
Octal, which is owned by Chemlink Capital Ltd. and Pound Capital Ltd., started operations quietly in December 2006 with a 44-million-lb/yr plant in Oman. Another 22 million lb was scheduled to come on stream in September. With its expansion next spring, Octal says it will be five times larger than the next-biggest merchant producer of APET sheet. Octal’s sheet comes in thicknesses from 8 to 36 mils and widths from 6 in to 63 in.
A key focus for Octal is delivering gauge tolerance of ±1% compared with today’s standard of ±5%. “When gauge is held to less than 1% variation, packaging manufacturers know exactly how many trays they will produce per ton of APET sheet,” says Barenberg. “That also means that they don’t have to worry about unpredictable thin spots, making it possible to further reduce the sheet’s gauge to save cost.” Improved gauge control can result in 3% to 8% cost savings, Octal claims.
COC as enhancer
Topas Advanced Polymers Inc. is touting its crystal-clear Topas cyclic olefin copolymer (COC) as an enhancement for thermoformable materials like LLDPE, HDPE, and PP. Adding 10% to 20% COC is claimed to improve strength, broaden the forming temperature window, and reduce snapback or dimensional changes in formed parts. Moreover, COC is said to boost moisture barrier, rigidity, and clarity, while also potentially allowing downgauging and reduced cost. COC is also coextruded with PETG, PP, and PS in thermoformed blister packs and deep-draw medical containers.
Among the innovations displayed in the annual parts competition was what was said to be the first integrally colored thermoformed tonneau cover. Penda Corp., Portage, Wis., developed the cover for a 5 ft, 8 in. long truck bed, which debuts on the 2007 General Motors Silverado pickup truck. Up to now, colored tonneau covers have been painted FRP composites. The new cover is formed from a coextruded sheet of acrylic and PC/ABS with a specially developed tie layer. A key challenge was matching six GM body colors.
In packaging, PWP Industries, Vernon, Calif., has developed an innovative tamper-evident thermoformed package with a pull-open tab. Previous tamper-resistant packaging methods included shrink wrapping and thermoforming containers with removable tabs. Sara Lee has adopted the vacuum-formed PET package for various single-serve, “grab and go” foods. In addition, Wal-Mart has approved the tamper-evident system for so-called “Dip-n-Go” packaging.