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Blister Carded Packages
By Francis Butler National
Sales Manager Alloyed Company Incorporated
Rigid blister packaging offers
product visibility specifically for self-service retailing.
Carded blisters meet the needs of this merchandising technique
by offering prolonged shelf life and protection against
moisture, dust, infestation, pilferage and breakage. It also
provides tamper evidence, product visibility and instructions
for use.
Blisters are manufactured by
thermoforming. A plastic sheet is pre-softened by heating. Then
is clamped over a mold, drawn into the mold by a vacuum, removed
from the mold and cooled. Accurate tooling and molds are key to
producing good consistent blisters of virtually any size and
shape.
The basic components of a
blister pack are the preformed plastic blisters; the heat-seal
coating; the printing inks and the paperboard card.
1
Plastic sheet
Plastic sheet for blister
packages is available in a range of grades and thicknesses. In
selecting one, the packager must consider the size and weight of
the products to be packaged, their value, their impact
resistance and whether they have sharp or pointed edges.
Heat-seal properties and the ease of cutting and trimming the
formed blister must also be considered.
Rigid plastic sheet used for
blister packages generally falls into three categories:
cellulosics , styrenes and vinyls. Cellulosics are the most
popular. They include acetate, butyrate and propionate. All
three offer excellent clarity, superior thermoforming
characteristics, good heat sealability and oil and grease
resistance. The heat-seal temperature range of cellulosics is
generally higher than that of the other films.
Oriented styrene offers
excellent clarity but has low impact-resistance, shatters easily
and performs poorly at low temperatures. Impact styrene works
well under these conditions. Styrenes in general offer good
heat sealability and clarity.
Vinyls, which are generally
less expensive than styrenes, can be rigid or flexible. Vinyl
heat seals well to properly coated paperboard. It varies in
clarity from excellent to good and in color from yellowish to
slightly blue. Plasticizer can be added to increase cold
temperature resistance and impact strength.
2
Heat-seal coatings
The appearance and physical
integrity of a blister depends heavily on the quality of the
heat-seal coating which is applied to the face of the card.
Effective coatings offer good gloss, clarity, abrasion
resistance and hot tack.
Hot tack (adhering properties
achieved at high temperatures) is particularly important because
when packaged products are ejected from the heat-seal jig, the
entire weight of the package must be supported by a still warm
adhesive bond line.
Also, a coating of proper
weight must be applied to the paperboard card to achieve optimum
heat seals. The coating must be compatible with the card and
blister. A relatively low heat-seal temperature is desirable
for rapid sealing and prevention of blister-film distortion.
The most widely used coatings
for blister cards are solvent-borne vinyls. These lacquers have
excellent gloss and abrasion resistance. Water-borne acrylics
are gaining ground but require somewhat more care in coating
application; to achieve optimum appearance.
Printing inks may be applied to
paperboard by letterpress, gravure, offset, flexography or silk
screen. Inks must resist high heat-sealing temperatures,
abrasion, bending and fading and be safe for use with the
products in the packages.
They should not contain
excessive amounts of waste, hydrocarbon lubricants, greases,
oils or release agents.
Paperboard is the main
structural component of the carded blister pack. It is selected
according to the size, shape and weight of the product to be
packaged. Paperboard for blister packaging ranges in caliper
(or thickness) from 0.014 to 0.030 inches, with 0.018 to 0.024
inches being the norm.
Paperboard must have a surface
suitable for printing by the process and ink in use and be
compatible with the heat-seal coating process. It should
withstand the stresses of printing (primarily causing
delamination on offset) and still provide good fiber-tearing
bonds when heat sealed to the plastic blister.
The backer card may be either
recycled stock or solid bleached sulfate (SBS) board. Generally
speaking, SBS provides a more attractive package because of its
clean white surface and the fact that it accepts inks readily.
If cost is a consideration, recycled paperboard can provide
savings.
Through advanced thermoforming
equipment and creative designs, suppliers of blister packaging
have produced items such as cardless clamshells, reclosable
reusable blister packages, hinged packages and multi product
kits.
Blisters have upgraded
pharmaceutical packaging, too. A multiple blister sheet covered
with foil allows the tamper-evident, push-through dispensing of
pills or tablets. This package, with individual protective
blister compartments, offers an economical replacement for
conventional glass and plastic bottles.
Skin Carded Packages
By Burton T. Spottiswoode Skin
Packaging Industry Manager Polymer Products Department Du Pont
Company
Skin packaging involves placing
a product on a substrate material such as paperboard or
corrugated and drawing heated plastic film down tightly to the
board and around the product to make a secure, attractive
package. The product itself becomes the mold over which the
heated plastic film or "skin" is drawn.
Skin packaging is used in two
ways. For visual carded display, skin packages are typically
rack hung, and are a cost-effective alternative to blister
packs, five-panel cartons, fold-over cards and rack-hung
thermoforms. Costs are reduced because no tooling is needed to
make blisters, no mold change over is needed and significantly
reduced film gauges are common. Throughput may be faster or
slower than alternative methods depending on the product size,
configuration and volume.
A recent development in carded
display packaging is high speed (10-30 cycles per minute), fully
automatic machinery. Thermoform-fill-seal equipment, along time
standard for food packaging and medical device packaging, has
been modified by several manufacturers to run standard skin
packaging mastercards or paper roll stock. These systems lend
themselves to automatic product placement, making them
competitive with other high-speed systems. In addition, several
manufacturers of traditional skin-packaging machinery have
introduced high-speed systems, making such equipment more
attractive to high-volume users.
Also common is industrial skin
packaging to protect products in transit. Products as divergent
as computer tapes, lamps, service repair kits and table tops may
be skin packaged instead of using die-cut corrugated,
foam-in-place, foam peanuts and other stabilizing or dunnage
materials. Skin packaging offers high throughputs and full
visibility, usually at significant savings.
Polyethylene and ionomer are
the most commonly used skin-packaging films. Recently, however,
experiments have been conducted with co-extruded films combining
these two materials or copolymers. There may be film-cost
advantages with co-extruded films, however, there is generally a
sacrifice of strength and appearance vs. traditional films.
While some co-extruded films have been developed for adhesion to
unprimed paperboard, extreme caution must be used with respect
to paperboard over time. Such materials may offer more
value-in-use for industrial skin-packaging applications using
unprinted, unprimed corrugated.
Some skin-packaging films may
provide a fiber-tearing bond to unprimed, unprinted corrugated.
However, the long-term adhesion under varying conditions has not
yet been determined. Since inks bring a third dimension to the
system, adhesion to printed, unprimed paperboard is not yet
recommended.
Improper ink or board-ink
combinations can interfere with film-to-board adhesion, either
chemically or physically. Pre-production ink tests are important
to evaluate the compatibility of the ink system with the board
and film. Generally, proofs are prepared by the printer using
the ink and board specified. Sample skin packages are made with
these proofs to check for proper evacuation of air and adhesion.
The board is generally either a
Fourdrinier (solid bleached sulfate), cylinder (non-bending
chip, vat-lined or patent coated) or corrugated. Board must be
selected for its thickness, stiffness, porosity and ability to
support the product being packaged. Paperboard is most commonly
0.018 to 0.025 (but up to .054) caliper, while corrugated is
usually 200 pound-test minimum.
Board, ink and primer are
considered together because they combine to form a compatible,
porous, strong and attractive system that becomes the backbone
of the skin package. Clay-coated paperboard is usually not used
because of its lack of porosity. Porosity also may be decreased
by certain inks and heat seal coatings. If lower porosity
paperboards are used, they must be perforated to increase air
flow to ensure proper vacuum draw-down during heat sealing.
Skin packaging for visual
carded display offers a number of benefits. The packaging
operation is quick and uniform, the film's clarity and sparkle
enhance the item and the display method spurs impulse buying
because of product visibility and a large exposed graphics
area. Skin packaging also is ideal for multiple units on a
single card. The backing card may reduce pilferage of smaller
items that could be concealed if not mounted on a card. Skin
packaging is also tamper-evident.
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