Plasma coating protects wine in PET bottle

Artisan Wine Co., which is based in British Columbia's Okanagan Valley, launched its new Painted Turtle Semillion/Chardonnay and Cabernet/Shiraz wines in 750-mL coated PET wine bottles from Ball Corp. (www.ball.com) in March 2008. The bottles feature the Plasmax internal silicon oxide (SiOx) barrier coating from KHS Corpoplast North America (www.valueaddedbottling.com) that protects the wine inside the bottle from oxygen penetration and is easily removed during the PET-recycling process.

The bottles include aluminum screw caps from G3 Enterprises (www.g3enterprises.com) and front and back pressure-sensitive labels from Tapp Technologies, Inc. (www.tapptech.com). The seven-color paper labels are flexographically printed on a 10-color press, which also applies a matte varnish to the labels and a spot gloss varnish onto the turtle icon on the labels. The paper selected for the labels incorporates wet-strength properties to resist water when the bottle is placed on ice. The two varieties of wine, which are bottled in different bottle styles, are being sold through the Liquor Control Board of Ontario (LCBO).

Passive coating

“We identified market interest for alternative wine-bottle packaging, such as PET plastic bottles, and we felt it would be a good fit for our new Painted Turtle Brand,” says David Fallis, vp of operations at Artisan Wine Co. “The combination of the PET bottle and screw-cap closure gives our customers a more convenient, environmentally-friendly wine packaging choice.”

“Because Ball Corp.'s PET bottles are approximately one-tenth the weight of the average glass bottle, we can ship more bottles, empty or full, on a truck, than with glass,” says Fallis. “Glass wine bottles typically weighout the truck before they cubeout, but with PET, we can fill the truck. Overall, PET bottles help reduce greenhouse gas emissions through the supply chain. However, to use PET bottles for our wine, we knew that we would need a barrier on the bottle to keep oxygen from penetrating.

“After reviewing the systems on the market, we selected Ball Corp.'s Plasmax-coated bottles, because the silicon oxide is a passive barrier. The other coating technologies are scavenger systems that start dissipating as soon as they are applied.”

Fallis continues, “We can keep the bottles with the Plasmax coating in inventory as long as necessary without losing any of the barrier properties. Plus, the Plasmax barrier-coating that Ball uses makes these bottles very easy to recycle in the existing PET infrastructure.”

Coating technology has numerous applications

Ball is the only PET bottle manufacturer to offer Plasmax barrier-coating technology in North America, and is currently using it in many commercial applications, including wine, beer and flavored alcoholic beverages (see accompanying sidebar). Plasmax provides an enhanced, passive, internal barrier for oxygen-sensitive products and is FDA-compliant. Applied in a transparent, ultra-thin layer less than 100 nm thick (one billionth of a meter), the coating resists cracking, abrasion and delamination.

In addition, Plasmax does not degrade over time, so the length of time a bottle can be stored is not limited by the barrier material. Another advantage of Plasmax is its recyclablity. A recycling study conducted according to European PETCORE (PET Container Recycling Europe) protocols demonstrated that Plasmax is removable during the recycling process and does not negatively affect any of the PET test requirements.

Microwave pulses ignite gases to create cold plasma

The Plasmax process incorporates plasma-impulse chemical vapor deposition (PICVD), a technology in which bottles are placed in a vacuum chamber, where gas lances enter the bottles and inject a mixture of oxygen and hexamethyldisiloxane. Microwave pulses then ignite these gases to create cold plasma that causes the hexamethyldisiloxane to decompose into SiOx, CO2 and water. The SiOx forms an ultra-thin coating on the insides of the bottles, while the CO2 and water, which are byproducts of the process, are removed by vacuum. By modifying the microwave settings during the process, the coating is built up in layers that have different characteristics.

The first layer is an adhesion layer. This is followed by a flexible layer and, finally, a barrier layer. The entire process takes about three sec. An interesting feature of the PICVD process is that the chemical composition of the gas mixture can be changed between pulses to modify the different layers to optimize the final coating for different products.

Double-coating stations handle 12,000 bottles/hr

Ball Corp. produces the Plasmax-coated bottles at its plant in Watertown, WI on a Plasmax 12D machine from KHS. The Plasmax 12D is constructed using principles of KHS Corpoplast's stretch/blow-molding machine rotary platform using 12 individual double-coating stations.

The machine has an output of 12,000 bottles/hr and can handle bottle sizes ranging between 100 mL to 1.2 L. “We evaluated different coating techniques for our PET bottles several years ago, and determined that Plasmax was the best fit for out market,” says Bryan Tyree, director of plastic packaging innovations at Ball Corp. “The clarity is outstanding, and we believe that the barrier is the best suited for the applications that we serve.”

In this operation, PET bottles are delivered to the continuous-motion machine on an air conveyor that transports them neck-down. The bottles travel through three rotating starwheels in series that deliver them to the coating chamber.

The first of these wheels sets the pitch of the entering bottles. The next wheel inverts the bottles to a neck-down position, and the third meters the bottles two-at-a-time into individual chambers on the continuously rotating coating wheel. There are 12 chambers on the coating wheel. After the bottles are loaded, the chamber closes, and the coating process, as described above, takes place as the wheel rotates.

As each chamber rotates to the discharge position, the chamber opens and the bottles discharge into a starwheel, where grippers turn the bottles upright and transfer them onto an air conveyor.

“The PET bottles have worked out well for us,” says Fallis. “The bottles are the same diameter as other wine bottles we are running, so we didn't even have to invest in changeparts. They run the same as glass, except that they're quieter. They also are less expensive than glass bottles.”

Artisan Wine Co. has crafted an extensive portfolio of fine wines that are available primarily in western Canada and Ontario. Signature brands include Mission Ridge, Sonora Ranch, Painted Turtle, Wild Horse Canyon, Fork in the Road, 49 North and Rigamarole. Icewine from the new VQA brand, Ganton & Larsen Prospect Winery, is available in the U.S.