A new highly clarified polypropylene is taking dead aim at
polycarbonate in applications where design engineers are concerned about
potential health effects of bisphenol A (BPA) feedstock.
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Concepts Products of Vernon,
CA recently switched two containers made of polycarbonate to polypropylene
clarified with Millad NX8000, a new additive that reduces haze in PP 50 percent
compared to the previous industry standard. Other major food container
suppliers are also in the midst of review of possible PC replacements.
"With the high clarity imparted by Millad NX8000, we achieved the
see-through visibility that's so important in food storage products. In fact,
leftovers never looked so good. At the same time, we were able to address
consumer concerns regarding health and safety and environmental responsibility.
This initiative with Milliken also helped Home Concepts Products achieve its
goal of becoming a BPA-free company in 2009," said Michael Moghavem, CEO of
Home Concepts Products.
Clarified PP also saves money compared to polycarbonate, in part because
it's one-third less dense than PC. Prices for injection grades of PC run around
$1.70/lb versus 40 cents/lb for neat PP. The cost of clarified PP is about half
the cost of polycarbonate.
Traditionally, PC has offered a more upscale
look, plus rigidity and durability compared to a soft feel for PP. Publicity
about possible health
risks with the BPA components of polycarbonate, particularly in baby
bottles, has scared many consumers away from the material. Web
sites have even popped up alerting consumers to products that do and don't
contain BPA.
This is Tupperware's official position
on BPA: "On the strength of the repeated governmental scrutiny that
polycarbonate has had, Tupperware continues to believe the material is safe.
However, as Tupperware has the highest regard for the safety of the consumers
of its products and the functionality of these products, it will continue to
closely monitor this scientific debate and research the best materials for use
in its products."
Tupperware no longer uses polycarbonate for any
children's products, including baby bottles sold in the United States of
Canada. Polycarbonate is still used in a small percentage of the company's products,
primarily those intended for high heat resistance, as well as some serving lines.
Rubbermaid
also offers BPA-free and polycarbonate products.
According to Brian Burkhart, global marketing manager for Millad
clarifying agent, polypropylene can withstand heat, and is even being used in
baby bottles, which are often warmed in pans of water. "One of the key
attributes of polypropylene is that it is hot fillable," he said in an
interview with Design News. The heat deflection temperature of homopolymer PP
at 66 psi is 221F. Some other clear plastics lack adequate HDT, and even wilt
in a dishwasher.
There is also potential for highly clarified polypropylene
in several medical applications, such as syringe barrels, petri dishes and
housings for medical equipment. "Options are limited only by people's ability
to make use of it," says Burkhart. "Over time, I hope people will see this as a
new material and start to design around it because it really wasn't an option
in the past."
One example he offers: "We had a customer at one time who
told me they had a specification in their design limitations that said if a
thickness was above a certain dimension (2 mm), we wouldn't use PP. When we
showed them this material they got very excited and said we can change that
specification to a different number now."
Another environmental factor, says Milliken's Burkhart, is
the recyclability of polypropylene. "It goes right in with the other
polyolefins in many towns," he says. Many automotive engineers are also moving
to polyolefins for car interiors to improve their recyclability. Olefins such
as milk bottles and PP containers have similar densities and are removed
through recycling streams with the same process.
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