Note: Descriptions are shown in the official language in which they were submitted.
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Multi-layer metallized packaging material and method of making same
INVENTOR
John E. Cahill of Hampton, New Hampshire
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional patent application
no.
60/420,727 entitled "Multi-Layer Metallized Packaging Material and Method of
Making
Same," filed 23 October 2002, which is hereby incorporated by reference herein
in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a multi-layer metallized packaging
material and a
method of producing a multi-layer metallized packaging material.
[0004] 2. Description of the Related Art
[0005] In the packaging industry, packaging materials may comprise a plurality
of layers
of different materials combined together in order to exploit the different,
advantageous
properties of each material. The use of different materials provides an
optimum combination
for the particular kind of package or the particular product that is to be
packaged. It is
generally desirable for packaging materials to be able to withstand rough,
abusive treatment
and endure prolonged exposure to corrosive substances. The packaging further
preferably
provides an impervious barner to isolate substances within containers, reduce
or prevent
absorption and/or transmission of liquid components, contain fragrances and
flavors within
the packaging interior, and prevent oxygen and other ambient gases from
passing through the
packaging material. It is preferable for packaging material to be heat
sealable. It is also
desirable for the packaging material to be economical to manufacture.
[0006] Paperboard is widely used to form containers for packaging products. It
is
typical to use resin coatings, films, and foils in one or more layers to
provide a barner
between the contents of the container and the paperboard. Foils may also be
used to add a
decorative effect to the packaging. However, they typically require
complicated and
expensive equipment and procedures, utilize expensive resins, foils, and
films, and may be
incompatible with existing carton manufacturing systems. Furthermore, many
packaging
materials are subject to warping caused by distortion of one or more of the
layers.
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[0007] A typical packaging material in the prior art incorporating a metal
foil layer is
composed of a base of paperboard laminated to the metal foil, which is
supported on a paper
layer. The metal layer is generally placed on the paper layer by vacuum
deposition. An
adhesive is dispensed between the paperboard and the paper layer and the two
are laminated
together. In this design the metal foil is exposed as the outer surface of the
packaging
material. This design is problematic, however, as the metal foil layer is
unprotected and is
easily scuffed or scraped off the packaging material, limiting its function as
a barrier layer or
as a decorative feature. Additionally, it is difficult to print on the metal
foil layer as most
commercial inks do not bond well to metal. Therefore, expensive printing
processes must be
invoked, for example, using buried ink processes. Another alternative is to
print the paper
layer before depositing the metal layer at a low optical density such that the
ink can be seen
through the metal layer. Such a mufti-step process adds significantly to the
manufacturing
cost because the printing step must be planned well in advance and cannot be
performed in-
line with the rest of the package manufacturing process. There is no ability
to alter the print
design on the package to produce alternate designs in-line.
[0008] Another known packaging material process incorporating metal foil
involves
laminating a metal layer supported on a plastic web, for example,
polyethylene, to a
paperboard substrate. As before, the metal layer is generally placed on the
plastic layer by
vacuum deposition. In this process, an adhesive is dispensed between the
paperboard and the
metal layer and the two are laminated together. The metal layer is thereby
sandwiched
between the paperboard and the plastic. As a result, the plastic layer
provides a protective
coating over the metal and provides a surface that can generally be printed
on.. There are,
however, drawbacks to this process and packaging material design as well.
First, special
adhesives must be used in order to adhere the metal layer to the paperboard.
This can add
significant cost to the manufacturing process. Second, in order to assemble a
finished
package, a hot melt adhesive must be used in order to adequately adhere two
plastic layers
together. This requirement compromises efficiencies in gluing rates and slows
the
manufacturing process.
BRIEF SUMMARY OF THE INVENTION
[0009] The present invention provides a system and method for manufacturing a
multi-
layer packaging material comprising a substrate, such as paperboard, and a
metallic layer
adhered to the substrate. One or more extruded polymer layers are included in
the packaging
to add strength and barner to the final structure. The extruded layer also
serves to adhere the
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metallic layer to the substrate layer. The packaging material further includes
one or more top
layers over the metal deposit to provide heat sealability, to add an
additional barrier, to
protect the metal surface, and/or to provide a printable surface. The top
layer or layers of the
packaging material may comprise an extruded polymer, an aqueous emulsion, and
mixtures
thereof.
[0010] The packaging material is formed by laminating a metallized release
film to the
substrate using one or more laminating layers of extruded polymer. The
metallized release
film comprises a release film having a metal deposit applied to a first
surface of the release
film. The release film is then removed from the metal deposit and one or more
top layers of
extruded polymer or an aqueous emulsion are applied to the metal deposit to
form the
packaging material. The removed release film can be discarded or re-used for a
subsequent
application.
[0011] According to one aspect of the invention, a method of manufacturing a
metallized
packaging material is provided. The method comprises the steps of providing a
web of
paperboard, providing a release film with a metal deposit applied to a first
surface thereof,
laminating the metal deposit to a first surface of the paperboard, removing
the release film
from the metal deposit, and applying one or more top layers to the metal
deposit. The step of
laminating involves using one or more extruded polymer layers to form an
intermediate
layered structure.
(0012] According to another aspect of the invention, a method of producing a
packaging
material is provided, comprising the steps of: providing a web of paperboard,
providing a
release film with a metal deposit applied to a first surface thereof, and
applying one or more
extruded top layers to the metal deposit. The method further comprises
applying the
metallized release film to the paperboard such that the metal deposit adheres
to the
paperboard, removing the release film from the metal deposit, and applying one
or more top
layers to the metal deposit.
[0013] According to another aspect of the invention, a system for
manufacturing a
metallized packaging material is provided. The system comprises a lamination
station, a
stripping station, and a finalizing station. The lamination station laminates
a metallized
release film to a paperboard substrate. The metallized release film comprises
a release film
having a metal deposit on a first surface thereof. The stripping station
removes the release
film from the metal deposit after the metallized release film is laminated to
the paperboard.
The finalizing station applies a top layer to the metal deposit after the
release film is
removed.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 is a schematic view of the manufacturing process according to
a
preferred method of the present invention.
[0015] Figure 2 is a schematic cross-sectional view of the packaging material
produced
by the first lamination station.
[0016] Figure 3 is a schematic cross-sectional view of the packaging material
after the
release film is removed.
[0017] Figure 4 is a schematic cross-sectional view of the final packaging
material
product.
[0018] Figure 5 is a schematic view of a system for manufacturing the
packaging
material according to an alternate embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention provides an improved system and method for
producing a
metallized packaging material. The system and method produces a metallized
packaging
material efficiently and economically while reducing warping in the final
packaging product.
The present invention will be described below with reference to an
illustrative embodiment.
One skilled in the art will recognize that the invention is not limited to the
illustrative
embodiment and that variations may be made in accordance with the teachings
and scope of
the invention.
[0020] Refernng to Figure 1, a schematic representation of the process of
manufacturing
the metallized packaging material of an illustrative embodiment of the
invention is shown.
The system 10 for manufacturing the packaging material includes a paperboard
supply roll 20
for supplying a web of paperboard 22. The system 10 further includes a first
lamination
station 30 for laminating a metallized release film 32 to the paperboard 22
using at least one
extruded polymer layer 42. The first lamination station 30 includes a cooling
roll 36 and a
nip roll 38 cooperating with the cooling roll 36. A release film supply roll
34 supplies the
metallized release film 32 to the first lamination station 30. The metallized
release film 32
comprises any suitable release film having a metal deposit applied to a
surface of the release
film. An extrusion die 40 for extruding one or more polymer layers 42 onto the
paperboard
22 also forms a part of the first lamination station 30. The extruded polymer
layers add
strength and barrier to the final structure and also serve to adhere the
metallic layer on the
release film 32 to the paperboard layer 22.
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[0021] One skilled in the art will recognize that the extruded polymer layer
42 may
comprise a plurality of extruded or co-extruded polymer layers. The polymer
resin may be
melted in any conventional extrusion device and discharged through the die 40
to form a
descending sheet of molten resin which deposits into the nip between the
advancing web of
paperboard 22 and the metallized release film 32. The layer or layers 42 of
molten polymer
may be formed by extruding conventional polymeric materials, including for
example, but
not limited to, low, medium, or high density polyethylene, polypropylene,
polyester,
polyurethane, polyamide, and polyvinyl chloride as well as blends and
copolymers thereof.
[0022] The paperboard web 22 is paid out from the paperboard supply roll 20
and led
over the nip roll 38 in contact with the cooling roll 36. The metallized
release film 32 is
simultaneously paid out from the release film supply roll 34 and led over the
cooling roll 36,
which synchronously rotates with the nip roll 38. At the same time, a
continuous layer or
layers of molten or semi-molten polymer material, for example polyethylene, is
melted in a
conventional extruder and extruded through the die 40 in the form of a sheet
of molten resin
42. The molten polymer layer or layers are directed into the nip, i.e., the
point of contact
between the nip roll 38 and the cooling roll 36, between the metallized
release film 32 and the
paperboard 22. The molten polymer is extruded at a relatively high temperature
so that good
adhesion is obtained on the paperboard 22.
[0023] The.molten polymer layer 42 pressed from the die 40 constitutes the
lamination
or binder layer between the metal deposit and the paperboard 22 and further
provides an
additional barrier layer for the final packaging material. The extruded
polymer 42, not yet
solidified, is compressed between the paperboard 22 and one side of the metal
deposit, such
that a mechanical bond ensues between the polymer layer 42 and the paperboard
22 and
between the polymer layer 42 and the metal deposit. In this manner, the metal
deposit on the
release film 32 will be effectively bonded to the paperboard layer 22.
[0024] At the same time, the polymer layer 42 cools down and becomes
stabilized. The
polymer layer 42 contacts the metal deposit on the release film 32, which
contacts the cooling
roll 36. The extruded polymer layer 42 will be cooled down via the cooling
roll 36 and the
heat discharged from the polymer layer 42 will pass at the same time through
the metal
deposit of the release film 32. The metal deposit becomes heated and by heat
conduction
transfers thermal energy to the cooling roll 36. As a result, the polymer
layer 42 is cooled to
such an extent that the polymer solidifies at the same time that the polymer
layer 42 adheres
to the metal deposit of the release film 32.
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[0025] The web of paperboard 22, having the layer of extruded polymer 42
thereon, and
the metallized release film 32 are pressed together between the nip roll 38
and the cooling roll
36, and are thereby laminated. The resulting multi-layer intermediate laminate
50 produced
by the first lamination station 30 is shown in Figure 2. The schematic cross
section through
the intermediate laminate 50 shown in Figure 2 illustrates how the
intermediate laminate 50
produced in the first operation comprises a paperboard layer 22, an extruded
polymer layer
42, a metallic layer 32b comprising the metal deposit, and a release film
layer 32a.
[0026] The thus formed intermediate structure 50 is further cooled by abutment
against
the surface of the cooling roll 36 for a portion of its circumference. A first
guide roll 60
subsequently guides the intermediate multi-layer laminate 50 through the
manufacturing
system 10.
[0027] The release film may be metallized using any suitable means known in
the art.
According to one embodiment, a metallizer, comprising a high vacuum chamber
through
which a moving web of plastic release film is passed, is utilized to apply the
metal deposit
32b to the release film 32a. In the vacuum chamber, a thin, uniform layer of a
coating metal
is deposited on the top surface of the moving release film 32a. Suitable
materials for the
metal deposit 32b include aluminum, lead, copper, silver, gold, or any other
suitable metal for
forming a barrier against penetration of gas or liquids through the final
multi-layer packaging
material and/or for providing decorative design to the final multi-layer
packaging material.
The metal is vaporized in the high vacuum chamber and the metal vapor is
caused to
condense on a moving web of the release film 32a. The metal is typically
deposited on the
web in a thin, uniform layer. Such layers may be between 50 angstroms and 7
microns or
more in thickness. The metal deposit 32b may also be patterned by, for
example, chemically
etching a pattern in the metal layer 32b after its deposition onto the release
film 32a. One
skilled in the art will recognize that the metal deposit 32b may be applied to
the release film
32a through any suitable means known in the art.
[0028] The release film 32a may comprise any suitable material, including, but
not
limited to, polyester, polypropylene, polyamide, fluoropolymer,
trimethylpentane, polymer-
coated paper, or any material having suitable release properties, smoothness,
heat resistance
and tensile strength.
[0029] The cooling roll 36 may comprise a metal roll that is cooled by any
conventional
technique, for example, by passing a cooling medium, i.e., water,
therethrough. The
temperature of the cooling roll 36 is generally maintained at about 60°
F during operation.
However, one skilled in the art will recognize that the cooling roll may be
maintained at any
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temperature suitable for cooling and solidifying the polymer layers of the
packaging material.
The nip roll 38 may have a size and hardness suitable for applying pressure to
a web of
material.
[0030] The first intermediate laminate 50 next passes to a stripping roll 78
which
removes the release film 32a, while leaving the metal deposit 32b on the top
surface of the
extruded polymer laminate layer 42. The resulting multi-layer metallized
material 70 is
illustrated in Figure 3. As shown, the metallized material 70 comprises the
paperboard
substrate 22, one or more layers of extruded polymer 42, and a top metallic
layer 32b.
[0031] The removed release film 32a may be collected on a release film
collection roll
76 for further handling. The release film 32a may then be recycled and reused
for
manufacturing another web of packaging material. According to the illustrative
embodiment,
the release film 32a may be reused, thus realizing significant savings in
cost, increased
manufacture time and a reduction in waste. The removed release film may also
be discarded
or used for another application.
[0032] According to one embodiment, the release film 32a may include an
additional
coating, such as an acrylic coating, between the release film 32a and the
metal surface 32b.
When the release film 32a is removed from the first intermediate laminate S0,
the release film
32a leaves the coating on the metal surface 32b. The additional coating can
serve as a
printing surface or a primer for subsequent layers of the packaging material.
[0033] The metallized material 70 then passes through a second guide roll 74
to a
finalizing station 80 to finalize the packaging material. The final component
of the
manufactured packaging material comprises one or more top layers 72 deposited
on the metal
layer 32b. The top layer 72 comprises a heat sealable layer for sealing the
packaging
material. The top layer further serves as an additional barrier layer and
protective surface.
The top layer may be a printable surface for the packaging to provide
attractive graphics.
[0034] According to an illustrative embodiment, as shown in Figure 1, the top
layer may
comprise an extruded polymer material. The finalizing station 80 may therefore
include an
extrusion station, as shown in Figure 1, for extruding the polymer material
onto the metal
layer. As shown, the extrusion station comprises a second cooling roll 86 and
a second nip
roll 88 cooperating with the second cooling roll 86. The extrusion station
also includes a
second die 84 for extruding molten or semi-molten polymer onto the metal layer
32b to form
the top layer, according to one embodiment.
[0035] According to the first embodiment, the molten polymer forming the top
layer 72
is directed to the nip formed between the second nip roll 88 and the second
cooling roll 86.
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The metallized material 70 advances over the nip roll and the extruded polymer
deposits onto
the metal deposit layer 32b across the width of the metallized material 70.
The metallized
material 70, having the layer of molten extruded polymer thereon is pressed
through the nip,
and such that the molten polymer layer 72 adheres to the metal deposit layer
32b. The
extruded polymer top layer 72 is then cooled to hardness.
[0036] The final multi-layer packaging material 100 formed by the final
extrusion
operation is shown in Figure 4. As shown, the mufti-layer packaging material
produced
according to the teachings of the present invention comprises a paperboard
layer 22, a
polymer laminant layer 42, a metal layer 32b and a top layer 72. The polymer
laminant layer
42 and the top layer 72 may comprise a plurality of layers of extruded or co-
extruded
polymer. Alternatively, the top layer 72 may comprise an aqueous material to
enhance the
clarity of the packaging material or other suitable material. After
production, the resulting
mufti-layered packaging material 100 can be rolled up onto magazine reels 102
and be
employed in the production of packaging.
[0037] According to another embodiment, as shown in Figure 5, the top layer 72
alternately be composed of an aqueous emulsion applied to the metal layer 32b.
The
finalizing station 80 may comprise a coating station 81 having a drying
section 82 for coating
and drying the aqueous emulsion on the metal layer 32b. The use of an aqueous
material to
form the top layer enhances the clarity of the mufti-layer packaging material
100 and
provides additional heat sealability. For example, the top layer 72 may be
comprised of one
or a mixture of styrenated acrylic polymers formed from an aqueous emulsion.
The acrylic
copolymer preferably is a latex formulation which may be formed from monomers
including
acrylic acid, methylacrylic acid, esters of these acids, and acrylonitrile.
The coating station
81 may apply the aqueous emulsion through any suitable process known in the
art, including
for example, but not limited to, gravure coating, reverse gravure coating, and
rod coating.
The drying section 82 dries the aqueous emulsion on the metal layer to form
the top coat
through any suitable means known in the art, including for example, but not
limited to, hot air
.and infrared energy. One skilled in the art will recognize that any suitable
material and
means may be used to form the top layer 72 of the mufti-layer packaging
material 100.
[0038] According to one embodiment, the paperboard 22 may also have an aqueous
or
polymer coating on the side opposite to the extruded polymer layers 42 to
provide an
additional barrier. Alternatively, the additional aqueous or polymer coatings
may comprise a
printable surface, a heat sealable surface, and/or a protective surface.
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[0039] By using the processes of the present invention disclosed herein, a
cost effective
solution is achieved to provide a metal layer 32b in a mufti-layer packaging
material 100.
The metal layer 32b is more resilient because of the top layer 72 of
protective coating. The
top layer 72 of encapsulating coating may also provide a greater gloss or
sheen to the metal
layer 32b resulting in more attractive packaging. The mufti-layer packaging
material 100
provides additional efficiencies by being both printable on-line and amenable
to standard
packaging adhesives, rather than requiring a hot melt adhesive to seal
finished package
products.
[0040] The present invention provides significant advantages over prior
methods of
manufacturing metallized packaging materials. The removal of the release film
from the
packaging material, while leaving the metal deposit in the packaging material,
prevents or
reduces warping of the final packaging product during the manufacturing
process or during
carton finishing of a carton made from the packaging material. The invention
further results
in an economical, efficient and simplified manufacturing process that reduces
waste and cost.
[0041] Since certain changes may be made in the above constructions without
departing
from the scope of the invention, it is intended that all matter contained in
the above
description or shown in the accompanying drawings be interpreted as
illustrative and not in a
limiting sense. It is also to be understood that the following claims are to
cover all generic
and specific features of the invention described herein, and all statements of
the scope of the
invention which, as a matter of language, might be said to fall therebetween.
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