An industry leading Healthcare company harnessed the expertise of three key
vendors to identify a more cost-effective lidding
material printed on-line and sealed to thermoformed
trays holding medical instruments.
The company has achieved a significant
breakthrough in the packaging of medical instruments
that are gamma-sterilized in their packages. The
Mid-West US based firm is believed to be the
first to use a polyethylene film printed entirely
on-line rather than a medical grade paper or spun
bonded polyolefin for lidstock.
"Lidding costs have been cut by 45% on two
lines where 20 different products are packaged,"
says a senior project manager at one of the company's plants where the new film has been
in use since June. He also adds that the new material
wasn't adopted without thorough prequalification
and validation. "It included accelerated aging,
distribution tests, final inspection, bubble test,
seal strength, peel test, and burst test,"
says the spokesperson.
The company packages products like suction tubes
and connecting hoses used in surgery. At one plant, 20 different products are packaged on either
an R7000 or R530 horizontal form/fill/seal machine
from Multivac (Kansas City, KS). The R530, running
2 shifts daily, handles 11 different products always
in a 2 up format. The R7000 packs 9 products, but
tooling permits it to run in a 3, 5, or 7 up configuration.
It runs around the clock 5 days a week.
Until last July, the R7000 used lidding material
made of either medical grade paper or spunbonded
polyolefin. Static information like product identification,
company name, and catalog number was always preprinted
by the converter supplying the material. Variable
information like date and lot number was printed
on-line by ink-jet equipment from Markem. The R530,
on the other hand, applied only unprinted medical
grade paper as lidding. Unlike the R7000, it was
equipped with a flexographic printer that imprinted
the static information on-line. Variable information
was added on-line by another Markem ink-jet unit.
These methods and materials were inherited by the
facility when, in 1994, production and packaging
of this product line was moved to Mexicali from
a plant in Puerto Rico. In 1996, the plant manager took on
the challenge of making his location's packaging operation
more cost effective. Substituting inexpensive film
for the more costly medical grade paper and spun
bonded polyolefin was the objective from the start.
Printing the film lidding on-line for all 20 products
was also a key target. But the water based inks
used in medical packaging typically don't dry fast
enough on plastic film.
Vendors team up
What the company sought then, was a material
substitution that could only be made through new
technology. To develop it, the spokesperson harnessed the
talents of 3 ket vendors. Bell-Mark supplied 2 of
its FlexPrint®
in-line printers to the company, 1 for each Multivac.
Colorcon developed the necessary water based ink.
And Rexam Medical Packaging supplied the lidding
material. Retained were the Multivac thermoforming
/ lidding machines and the Markem ink-jet coders.
The 4 mil. lidstock is Rexam's Integra® Peel
product. From the outside in, this 3 layer blown
film coextrusion consists of high density polyethylene/HDPE/blended
low density polyethylene. The 2 outer layers of
HDPE differ slightly from each other. The outermost
one includes ingredients that enhance the ultimate
printability of the finished structure.
Colorcon's Jerry Napiecek says his firm demonstrated several years ago that a water based ink can be applied to such a film and dried on-line successfully if additional drying capacity is added to the flexographic printers. But full commercialization of such inks had to wait until manufacturers of flexographic printers were willing to incorporate the necessary drying units on the machines they build.
So far the only printer maker to show a willingness is Bell-Mark, says Napiecek. On the printers it installed at the company's locations, the first thing the freshly printed lidding encounters as it exits the print station is an air plenum that stretches across the full width of the film. It blows air at temperatures from ambient to 180° F to help dry the ink.
The plenum is aimed so that none of the air is directed back onto the printing plate or anilox roll, which could cause the ink to dry before it's delivered to the lidstock. As critical as this air plenum is, the Bell-Mark system has 2 other features that contribute significantly. One is the enclosed doctor blade, which keeps air from reaching the ink and drying it prematurely. The other key feature is timing. The FlexPrint differs from other on-line printing and coding systems, where the print drum receives ink immediately after the previous imprint. That method can allow too much time for drying before the ink is delivered to the substrate. It isn't a problem on spun bonded polyolefin or medical grade paper because the ink used on such substrates doesn't evaporate so quickly. It doesn't have to dry so quickly because these substrates absorb it readily.
With the fast drying Colorcon inks that the company
uses, the lag between application of the ink on
the drum and imprint on the substrate is kept to
an absolute minimum. With the aid of a PLC, the
print drum doesn't rotate past the anilox roll for
fresh ink until the instant before the next print
cycle. Could faster drying solvent based inks have
been substituted for the water based variety? Probably
not for medical packaging. Solvent emissions just
aren't acceptable in a clean room environment, and
venting them outside presents problems with clean
air regulations and/or incineration equipment.
Film is a challenging substrate
Rexam's Dan Penny appreciates the effort that
went into the Bell-Mark system and its effectiveness
in printing on a film substrate. "Paper and
spun bonded polyolefin are so much easier because
they absorb some portion of the ink," he says.
"But when you print on film, all the ink is
sitting directly on the surface. If you don't get
the right surface tension in the ink, you wind up
smearing everything. It took considerable work on
Bell-Mark's part to refine the process and take
it to a user friendly stage. It's one thing to do
it in the lab. It's another thing doing it around
the clock at a medical device manufacturer's plant."
Colorcon's contribution to the company's project
was no small feat either. It formulated an ink that
would stay "open," as Napiecek puts it,
on the DuPont Cyrel® photopolymer plate, yet
dry fast enough after application to avoid being
smeared or picked off the substrate. "It was
certainly not a standard formulation," says
Napiecek. He also credits Bell-Mark's people. "Without
a buy-in from the engineers at Bell-Mark, it would
have been impossible to pull this off."
Rexam
also supplies the monolayer forming the web, a 10
mil. Integra® Form Peelform® Plus, which
is blown from a LDPE blend. Maximum depth of draw
on the company packs is 1 3/4", and machine
speeds on the 2 lines are similar, with cycle times
in the 13 to 15 /min. range. The company is so pleased
by the material cost savings gained by the switch
in lidding materials that it now plans a similar
transition at a plant in Malaysia. "Cost savings
drives it all," says the spokesperson. "The medical
device business is very competitive, so you have
to do what you can to reduce cost while mainatining
quality."
