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Bottle-to-bottle PET recycling beckons in Germany

German mineral water and soft drink marketer Rosbacher installs a first-of-its-kind stretch blow molder and seeks to popularize closed-loop recycling of PET beverage containers.

Four crates are filled with each cycle of this machine. Each gripper aligns its bottle so that when bottles land in the crate, l
Four crates are filled with each cycle of this machine. Each gripper aligns its bottle so that when bottles land in the crate, l

German law stipulates that 72% of all beverage containers must be refillable, so one-way plastic beverage containers are rare. That's what makes Rosbacher--a beverage company officially known as VMH Mineral-und Heilquellen GmbH & Co. KG, Rosbach--so intriguing. Based in the German city of Rosbach near Frankfurt, this company has begun marketing four flavors of Frischa- brand carbonated soft drinks

in one-way 1-L plastic bottles made of polyethylene terephthalate. But don't let marketing manager Silvia Erbrich catch you calling Rosbacher's bottles "one-way PET" just because they're not refillable.

"We don't view these as 'one-way' bottles," states Erbrich. "We produce the bottles from preforms and fill them for shipment to wholesalers, retailers and finally consumers. But the bottles have a deposit, so the empties come back to us. We compress the empty bottles and ship the baled material to a reprocessor so the material can be used again."

Currently most of this reprocessed resin finds its way into non-bottle applications, typically fiber or strapping. But Rosbacher is part of an ambitious test to see if bottle-to-bottle recycling can be perfected. More on that later.

As if considering bottle-to-bottle recycling in Germany wasn't ambitious enough, Rosbacher is also the first to make bottles via the recently developed Contiform blow molding system from Krones (Franklin, WI). The Contiform heads the sophisticated in-line blow/fill system used for the 1-L Frischa bottles.

The 16-station Contiform is unusually compact. Unlike conventional reheat-and-blow systems, which have heating and blowing units positioned side by side, the heating unit and the blowing unit are arranged one above the other and are connected by a vertically operating transfer starwheel. Thus configured, the Contiform occupies a footprint of just 12 sq m (129 sq') and has a total height of 2.55 m (81/2').

According to Krones, the rated speed of the 16-station Contiform is 320 bpm. But Rosbacher's line is designed for speeds in the 240/min range, so blow molding is carried out at that speed, too.

According to Stefan Lamprecht, general technical manager at Rosbacher, the Contiform's small footprint was certainly an appealing feature. So was the nameplate on the machine, he says.

"We have had good experiences with Krones," says Lamprecht. "Besides, the machine is practically a prototype, which made the price attractive. Also, we wanted a single supplier on this line, and that was something Krones could offer."

What prototype?

Despite its near-prototype status, the Contiform has performed admirably, says Lamprecht. "In a short time it reached efficiencies that were very impressive," he says.

Preforms enter the Contiform via a steeply angled feed rail. All parameters--preblowing, blowing time, temperature, venting, etc.--can be set from a touchscreen display.

An infeed starwheel grasps preforms from the feed rail with a clamp in the space between the thread and the support ring. It transfers each preform to a transport pin in the heating unit. To ensure optimum temperature distribution, the preforms are rotated as they travel through the heating section. The reflector-type heating modules, each with 10 horizontally installed infrared heating elements, guarantee that the desired temperature profile is precisely maintained. Air blown at the preforms during the heating stage prevents overheating of the preform's surface at the same time that it

drives heat past the skin layer to the material in the inner wall of the preform. The sensitive neck area is also cooled to prevent deformations; in this case the cooling is accomplished by piping that circulates cold water through the transport pin where it contacts the neck finish.

After traveling through the heating module, the preforms enter specially designed starwheels that pass the preforms down a short distance to the level at which blowing occurs. Once the preform has been fed into the blowing station, the mold closes and locks. While the mold is still being closed, the blow nozzle descends, and the stretching rod initiates the stretching operation as soon as the mold is locked.

Pre-blow pressure of 5 to 9 bar is applied, ensuring optimum

distribution of the material. Blow molding is completed with a higher pressure of 40 bar. The stretching rod is withdrawn, and after cooling and venting, the mold opens. The finished bottle is transferred to a discharge star and passed on to the air conveyor supplied by Ling Systems (Cambridgeshire, England).

Next, another compact system accomplishes a lot in a small amount of space. Supplied again by Krones, it's the PET-Superbloc: a 40-head Variojet rinser, a 60-valve Mecafiller, a 10-head screw capper and a rotary labeler with 15 bottle platforms. All four machines are mechanically synchronized to operate as one.

Cut paper labels are applied by the Canmatic labeler. The labeler has two independently operating hot melt stations. The first applies a strip of hot melt glue to the bottles. While the bottle rolls past the label magazine, it uses its glue strip to pick off the frontmost label from the magazine. The second station, meanwhile, applies glue to the end of the label so an overlap seal can be made.

A mechanically driven date coder integrated into the labeling machine prints a best-if-used-by date on each label. Also part of the system is a Krones Checkmat unit that inspects for and rejects incorrectly labeled bottles. The other inspection device in the system is an infrared fill-height detector that kicks out bottles with incorrect fill heights.

Neck-handling feature

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