[GRRN] Plastic Beer Bottles - Aluminum Caps

RecycleWorlds (anderson@msn.fullfeed.com)
Tue, 9 Feb 1999 11:40:45 -0600

In a message on 2/9, Pat Franklin asks, with regard to the Miller
plastic beer bottle:

"There is another issue I haven't seen mentioned lately and that is the
aluminum closures which contaminate the PET material.
Any comments on that???"

The answer is that, as had previously occurred in PET soft drink
bottles, Miller's aluminum caps are a significant problem.

Historically, beer sold in screw top glass bottles has used aluminum
caps, and Miller has continued the same cap on its plastic bottle. This
repeats the situation that previously occurred when the early generation
PET soft drinks bottles were launched using aluminum caps like their glass
bottle counterparts. Recyclers' attempts to add equipment to mechanically
separate the aluminum wound up being totally impractical. Eddy current and
electrodynamic separators were hooked up in series, but they were very
expensive and required the plastic stream to be dried before the equipment
would work properly. Also, because the ground caps curled up around the EVA
liner during the wash process, the presence of that piece of plastic
confounded the machines' detection capability. In that case, a
polypropylene (PP) cap was developed as a replacement, with a PVC, and
later, when PVC became a problem, an EVOH, liner to provide a seal against
the loss of carbonation. While the PP cap was initially slightly more
expensive than the aluminum one, as volume sales of plastic caps mounted,
the price came down to be competitive with aluminum.

Such a PP cap design will not be immediately adaptable to beer because
the limiting condition for beer is oxygen ingress, not carbonation egress
as in soft drinks. In any event, it is generally accepted that this problem
can be engineered around, and in the United States Owens- Brockway, and no
doubt others, are presently working on a plastic beer cap that will float
off in the sink/float tanks used by processors.

We at the 32 state Plastic Redesign Project have a detailed report on
the full spectrum of issues surrounding plastic beer bottles, and I can
email a copy of that report as a WordPerfect document file attachment to
anyone who sends me their email address. I also can convert it to a Word
file, although not all of the graphics may line up exactly.


Peter Anderson
RecycleWorlds Consulting
4513 Vernon Blvd. Ste. 15
Madison, WI 53705-4964
Phone:(608) 231-1100/Fax: (608) 233-0011