The introduction of blow molded OPP bottles and jars at commercial speeds with clarity equal to polyethylene terephthalate (PET) and with desired hot fill and barrier properties, now makes PP a cost-effective alternative to glass, PET, composite cans and multilayer cartons for a broad variety of applications. Until now, PP applications have been limited to water bottles, pill vials and other containers where oxygen barrier properties were not critical.
LyondellBasell and CCC worked closely in developing Pro-fax X11540-81-3 for this application. The launch is also a result of CCC’s partnerships with South Africa’s Council for Scientific Industrial Research (CSIR) , and a strategic equipment manufacturer in China, who has custom-built the ISBM equipment for CCC.
Marketed under CCC’s Enviroclear Barrier System® brand name, the OPP bottles and jars feature patented oxygen and CO2 barrier coating, applied through a dip/spray process, which creates the enhanced performance characteristics. The coating improves the oxygen barrier on a 500 ml OPP bottle by approximately 140 times over an uncoated PP version, according to Lorie Struzik, technical program manager at LyondellBasell.
“The barrier improvement when applied to a PP bottle is ten times better than a same-size uncoated PET bottle,” explained Norman Gottlieb, chief executive officer, CCC.
“We have commercialized a cost-effective process to injection stretch blow mold two-stage OPP bottles into bottles and jars that are as clear as PET,” added Gottlieb. Central to this commercialization is a customized 40 dg/min clarified random copolymer from LyondellBasell which makes it the first PP able to achieve clarity and performance properties without the use of peroxide to enhance melt flow.
Dave McKeeman, LyondellBasell’s new business development manager for injection molding, said, “Pro-fax X11540-81-3 is a 40 melt-flow, reactor-grade product optimized for adhesion of the oxygen barrier coating. This resin also contains no peroxide. What has typically been done in the past is to take a 12 melt flow base flake and visbreak it in a pelletizing extruder with peroxide to achieve a higher 35 melt flow so that parts could be produced more rapidly.”
McKeeman added, “Because the old process required the polymer chains to be broken in order to achieve improved melt flow characteristics, some of the stiffness had to be sacrificed. For the first time, LyondellBasell has been able to make commercially available a grade that comes out of the reactor at a 40 melt flow, eliminating the need to add peroxide or visbreak the chain to enhance performance. This not only gives blow molders a peroxide-free alternative at commercially-desired speeds, but it also creates stiffer bottles which, in turn, better enables hot-fill applications.”
The other key aspect of LyondellBasell’s Pro-fax X11540-81-3 is that the bottles have improved adhesion properties. This means that the coating adheres tightly and does not rub off when the bottles bump against each other in the filling line. In turn, this helps maintain the bottle’s barrier attributes.
“Additionally, the high melt flow allows you to injection mold preforms at a lower melt temperature which means less cooling time. The end result is that you can eject the part more quickly, which gives you faster production speeds,” McKeeman said. “And, even though PP is not as stiff as PET, its lighter specific gravity makes it possible to reduce the bottle weight by 10% [compared to PET] and still achieve equivalent stiffness.”
At CCC’s Toronto facility, LyondellBasell’s Pro-fax X11540-81-3 is run on an injection molding unit to create the preform. The preform then travels to the proprietary 10-cavity, rotary Enviroclear® ISBM machine where it is blown into its final shape. (The unit has been specifically engineered to blow containers within the tighter processing window necessary for OPP.) The biaxial orientation helps the bottles achieve crystal clear clarity. The barrier coating is added in a third step through a proprietary dip/spray process.
“The proprietary equipment enables us to produce both bottles and jars, in wide- and narrow-neck variations. We are in the process of gearing up production to rates of up to 14,000 bottles per hour,” Gottlieb says.
The availability of the technology will now open doors for customers to use the product in a wide variety of commercial applications. Ideal conversions include food, beverage and pharmaceutical categories including single-serve hot-fill juices, pasteurized milk and tomato-based products. Various applications are currently being tested with commercializations expected to reach shelves towards the end of 2008.
Container Corp of Canada is headquartered in Richmond Hill (Toronto), Ontario and specializes in both plastic and corrugated packaging. For more information visit: www.containercorp.com.