U.S. patent application number 14/907356 was filed with the patent office on 2016-06-16 for metallized laminated structures for food packaging.
The applicant listed for this patent is BEMIS COMPANY, INC.. Invention is credited to Alison J. Umbarger.
Application Number | 20160167855 14/907356 |
Document ID | / |
Family ID | 52483975 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160167855 |
Kind Code |
A1 |
Umbarger; Alison J. |
June 16, 2016 |
METALLIZED LAMINATED STRUCTURES FOR FOOD PACKAGING
Abstract
The present invention relates to improved metallized laminated
structures for making rigid food containers and more particularly
to metallized laminated structures for making rigid food containers
having a lustrous metallic appearance formed from a laminate
comprising a first substrate of thermoformable thermoplastic
material; a first metallized layer of vapor deposited tin bonded to
the substrate of transparent thermoplastic material; a second
metallized layer of vapor deposited aluminum bonded to the first
metallized layer of tin; a second substrate of thermoformable
thermoplastic material; and a recessed cavity having a food contact
surface.
Inventors: |
Umbarger; Alison J.;
(Appleton, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BEMIS COMPANY, INC. |
Neenah |
WI |
US |
|
|
Family ID: |
52483975 |
Appl. No.: |
14/907356 |
Filed: |
August 19, 2013 |
PCT Filed: |
August 19, 2013 |
PCT NO: |
PCT/US13/55525 |
371 Date: |
January 25, 2016 |
Current U.S.
Class: |
206/524.2 |
Current CPC
Class: |
B32B 2307/41 20130101;
B32B 2439/40 20130101; B32B 7/12 20130101; B32B 27/08 20130101;
B32B 2255/28 20130101; B32B 2307/402 20130101; B32B 2250/02
20130101; B32B 2605/00 20130101; B32B 2255/205 20130101; B32B
2307/732 20130101; B32B 2307/518 20130101; B32B 2307/406 20130101;
B32B 2439/70 20130101; B32B 2307/414 20130101; B32B 1/02 20130101;
B32B 2307/416 20130101; B32B 3/28 20130101; B65D 65/40 20130101;
B32B 2255/10 20130101; B32B 2307/738 20130101; B32B 27/302
20130101; B32B 2307/412 20130101; B32B 27/32 20130101; B32B 2605/08
20130101; B32B 27/36 20130101; B32B 2439/66 20130101 |
International
Class: |
B65D 65/40 20060101
B65D065/40 |
Claims
1. A thermoformed metallized food container formed from a laminate
comprising: a first substrate of thermoformable transparent
thermoplastic material; a first metallized layer of vapor deposited
tin bonded to the first substrate; a second metallized layer of
vapor deposited aluminum bonded to the first metallized layer of
tin; a second substrate of thermoformable thermoplastic material;
and a recessed cavity having a food contact surface.
2. The container of claim 1, wherein the first metallized layer of
tin is substantially continuous across the surface of the first
substrate.
3. The container of claim 1, wherein the second metallized layer of
aluminum is non-continuous across the surface of the first
metallized layer of tin.
4. The container of claim 1, wherein the first substrate of
thermoplastic material is transparent.
5. The container of claim 1, wherein the second substrate of
thermoplastic material is black or opaque.
6. The container of claim 1, wherein the first substrate of
thermoplastic material is polyethylene terephthalate.
7. The container of claim 1, wherein the first substrate of
thermoplastic material is polyethylene.
8. The container of claim 1, wherein the second substrate of
thermoplastic material comprises amorphous polyethylene
terephthalate or high-impact polystyrene.
9. The container of claim 1, wherein the first substrate of
thermoplastic material is a first outer surface of the
container.
10. The container of claim 1, wherein the second substrate of
thermoplastic material is a second outer surface of the
container.
11. The container of claim 1, wherein the second substrate of
thermoplastic material has a thickness of at least about 336.6
micron (about 13.4 mil).
12. The container of claim 1, further comprising a layer of
adhesive in direct contact with the second metallized layer of
aluminum and the second substrate of thermoplastic material.
13. The container of claim 1, wherein the recessed cavity has a
draw depth of at least about 0.635 centimeter (about 0.25
inch).
14. The container of claim 13, further comprising a lidding film
covering the recessed cavity and sealed to the container.
15. A thermoformed metallized food container formed from a laminate
comprising: a first substrate of thermoformable transparent
thermoplastic material of oriented polyethylene terephthalate or
polyethylene; a first metallized layer of vapor deposited tin
bonded to the first substrate: a second metallized layer of vapor
deposited aluminum bonded to the first metallized layer of tin; a
second substrate of black or opaque thermoformable thermoplastic
material of amorphous polyethylene terephthalate or high impact
polystyrene; a layer of adhesive in direct contact with the second
metallized layer of aluminum and the second substrate; and a
recessed cavity having a food contact surface.
16. The container of claim 15, wherein the first metallized layer
of tin is substantially continuous across the surface of the first
substrate.
17. The container of claim 15, wherein the second metallized layer
of aluminum is non-continuous across the surface of the first
metallized layer of tin.
18. The container of claim 15, wherein the second substrate of
thermoplastic material has a thickness of at least about 336.6
micron (about 13.25 mil).
19. The container of claim 15, wherein the recessed cavity has a
draw depth of at least about 0.635 centimeter (about 0.25
inch).
20. The container of claim 15, further comprising a lidding film
covering the recessed cavity and sealed to the container.
Description
BACKGROUND OF THE INVENTION
[0001] This invention is concerned with metallized laminated
structures for making rigid food containers and more particularly
to metallized laminated structures for making rigid food containers
having a lustrous metallic appearance.
[0002] It is often desirable to provide a metallic reflective
appearance to plastic articles, such as, rigid plastic food
containers for decorative purposes. One approach to achieving this
objective is to metallize a sheet or film of thermoplastic material
followed by thermoforming the metallized sheet into a desired
shape. Metals which impart particular brilliant reflectivity
include silver, gold, copper and aluminum. However, silver, gold
and copper are very expensive for large-scale manufacturing use and
aluminum is relatively brittle making it difficult to thermoform.
Unfortunately, the degree to which such aluminum metallized
polymeric substrates can be shaped or thermoformed without the
metal rupturing and/or separating from the polymer surface is
generally limited to forming involving relatively small dimensional
changes. The visual effect of rupturing and/or separation of the
metal from the polymeric substrate is a noticeable loss of specular
reflectance.
[0003] Therefore, there is a need in the art for improved
metallized laminate structures for fabricating rigid food
containers that exhibit excellent specular reflectance after
undergoing substantial dimensional changes.
SUMMARY OF THE INVENTION
[0004] The present invention is concerned with thermoformed
metallized food containers formed from a laminate comprising a
first substrate of thermoformable thermoplastic material; a first
metallized layer of vapor deposited tin bonded to the substrate of
transparent thermoplastic material; a second metallized layer of
vapor deposited aluminum bonded to the first metallized layer of
tin; a second substrate of thermoformable thermoplastic material;
and a recessed cavity having a food contact surface. The first
substrate of thermoplastic material may be a monolayer sheet or
multilayer film. Preferably, the first substrate of thermoformable
thermoplastic material is transparent or translucent. The second
substrate of thermoformable thermoplastic material may be a
monolayer sheet or multilayer film. Preferably, the second
substrate of thermoformable thermoplastic is black and/or opaque.
The present invention may further comprise a layer of adhesive
being in direct contact with the second metallized layer of
aluminum and the second substrate of thermoformable thermoplastic
material.
[0005] The present invention also provides an end-product of a
metallized rigid food container having a food product sealed within
a metallized laminate which has been formed into a recessed cavity
and covered by a lidding film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 depicts one embodiment of a thermoformed container of
the present invention.
[0007] FIG. 2 illustrates an enlarged cross-sectional view of one
embodiment of a metallized laminate of the present invention having
a monolayer first substrate and a monolayer second substrate.
[0008] FIG. 3 illustrates an enlarged cross-sectional view of
another embodiment of a metallized laminate of the present
invention having a monolayer first substrate and a monolayer second
substrate.
[0009] FIG. 4 illustrates an enlarged cross-sectional view of
another embodiment of a metallized laminate of the present
invention having a monolayer first substrate and a monolayer second
substrate where both the first and the second substrates are
metallized.
[0010] FIG. 5 illustrates an enlarged cross-sectional view of an
embodiment of a metallized laminate of the present invention having
a multilayer first substrate and a monolayer second substrate.
[0011] FIG. 6 illustrates an enlarged cross-sectional view of an
embodiment of a metallized laminate of the present invention having
a monolayer first substrate and a multilayer second substrate.
[0012] FIG. 7 illustrates an enlarged cross-sectional view of the
metallized laminate of FIG. 3 that has been thermoformed into a
three-dimensional shape.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Referring now more particularly to FIGS. 1-2 of the
drawings, a preferred embodiment of container 10 embodying a
laminate 100 of the present invention is shown. The container 10 is
shaped or otherwise molded to form a recessed cavity 30 having at
least one sidewall 31 and a bottom portion 32. Container 10 may be
formed from a laminate 100 which comprises a first thermoformable
thermoplastic substrate 11 and a second thermoformable
thermoplastic substrate 12. For example, the first and second
thermoplastic substrates may each include a material which is
normally solid at room temperature and can be readily shaped or
formed into a desired contour such as a bowl, cup and the like.
Such thermoformable thermoplastic materials may include monolayer
sheets and multilayer films formed from homopolymers or copolymers
of polyethylene terephthalate, polyolefins including, but not
limited to, polyethylenes and polypropylenes, polystyrenes,
polyvinyl chlorides, cyclic olefins and blends thereof. In one
preferred embodiment, first thermoplastic material 11 is a
transparent monolayer sheet or transparent multilayer film of
thermoformable polyethylene terephthalate, more preferably, a
transparent monolayer sheet or multilayer film of oriented
thermoformable polyethylene terephthalate, and most preferably, a
transparent monolayer sheet or transparent multilayer film of
biaxially oriented thermoformable polyethylene terephthalate. The
thickness of the first thermoplastic material 11 may vary depending
upon the desired end-use. Typically, the thickness of a monolayer
of biaxially oriented polyethylene terephthalate film 11 is between
about 48 gauge and about 150 gauge (about 12.2 micron and about
38.1 micron) and preferably, between about 50 gauge and 100 gauge
(about 12.7 micron and 25.4 micron) and more preferably, about 75
gauge (about 19 micron). An example of a suitable commercially
available thermoformable oriented polyethylene terephthalate film
is 75 gauge Skyrol.RTM. SKC SL80C supplied by SKC, Inc. (Covington,
Ga.). First thermoplastic material 11 forms a first outer surface
of the container 10.
[0014] Laminate 100 of container 10 further comprises a first
metallized layer of tin 21 which may be prepared by applying tin to
the first layer of thermoplastic material 11 by any conventional
metallization technique known to those skilled in the art. An
especially preferred metallization technique in the practice of
this invention is vacuum deposition wherein the metal is vacuum
evaporated and then deposited onto the polymer layer as described
by William Goldie in Metallic Coating of Plastics, Vol. 1,
Electrochemical Publications Limited, Chap. 12 (1968), the
disclosure of which is incorporated herein by reference in its
entirety. The first metallized layer of tin 21 may be preferably
deposited by vapor deposition techniques, typically by applying the
molten metal under vacuum by such techniques as electron beam
evaporation, sputtering, induction heating, or thermal evaporation.
A particularly preferred technique for metallization of tin is by
electron beam vacuum evaporation deposition methods.
[0015] The tin is deposited at a layer thickness that forms an
initial continuous metal film. Later, after laminate 100 is formed
into its final shape, first metallized layer of tin 21 may be
distributed more evenly over first substrate of thermoplastic
material 11. The thickness of the tin layer should be in a range
such that it provides good adhesion to the substrate and has good
mechanical strength. Thickness of a metal layer is most easily
specified by reference to the optical density measured immediately
after coating of the metal onto the substrate. The amount of tin
applied to the first substrate of thermoplastic material 11 should
adjusted to achieve an optical density of between about 1.0 and
about 4.0 higher than the optical density of the first substrate of
thermoplastic material 11. First metallized layer of tin 21 may be
formed as an uninterrupted continuous layer of metal or a
non-continuous layer metallic islands extending over first
substrate of transparent thermoplastic material 11. In order to
promote better adhesion between first substrate of thermoplastic
material 11 and first metallized layer of tin 21, it is also
contemplated that the surface of first substrate of thermoplastic
material 11 may be corona treated before the metallization process
occurs. In a preferred embodiment of the present invention, first
metallized layer of tin 21 is formed by electron beam vacuum
deposition of tin onto a corona-treated surface of a 75 gauge
(about 19 micron) thermoformable oriented polyethylene
terephthalate film.
[0016] Without being bound to a particular theory, it is believed
that the use of tin as the first metallized layer 21 in combination
with conventional thermoforming processes operating at a
temperature range of between 343.degree. C. and 371.degree. C.
(650.degree. F. and 700.degree. F.) provides a synergistic result.
Because tin has a melting point of about 232.degree. C. (about
449.degree. F.), it is molten during the thermoforming process and
becomes more evenly distributed over the surface of first
thermoplastic substrate 11. The improved distribution of the tin
provides a more lustrous metallic appearance to the formed
container 10.
[0017] Following the formation of the tin layer, a second
metallized layer of aluminum 22 is applied over the first
metallized layer of tin 21 by the same or different metallization
technique used to create the tin layer. In a preferred embodiment,
the second metallized layer of aluminum 22 is provided by thermal
vacuum deposition of aluminum onto a first metallized layer of tin
21. Second metallized layer of aluminum 22 may be applied as a
continuous metal film over the tin, but after the forming process,
the aluminum becomes discontinuous islands of metal covering the
tin. The total amount of aluminum applied to the tin is adjusted to
achieve a cumulative optical density of between 2.0 and about 4.0
higher than the optical density of the first layer of thermoplastic
material 11. In one embodiment, the optical density of the first
metallized layer of tin 21 is 1.0 higher than the optical density
of the first substrate of thermoplastic material 11 and the optical
density of the second metallized layer of aluminum 22 is also 1.0
to achieve a cumulative optical density of 2.0 higher than the
optical density of the first substrate of thermoplastic material
11. In another embodiment, the optical density of the first
metallized layer of tin 21 is 2.0 higher than the optical density
of the first substrate of thermoplastic material 11 and the optical
density of the second metallized layer of aluminum 22 is 1.0 to
achieve a cumulative optical density of 3.0 higher than the optical
density of the first substrate of thermoplastic material 11. In a
preferred embodiment, the optical density of the first metallized
layer of tin 21 is 3.0 higher than the optical density of the first
substrate of thermoplastic material 11 and the optical density of
the second metallized layer of aluminum 22 is 1.0 to achieve a
cumulative optical density of 4.0 higher than the optical density
of the first substrate of thermoplastic material 11.
[0018] Those skilled in the art will recognize that a typical
vacuum deposited layer of aluminum having an optical density of 1.0
will be approximately equivalent to a thickness of about 364
Angstrom. In a preferred embodiment, the second metallized layer of
aluminum 22 is provided by thermal vacuum deposition of aluminum
onto a first metallized layer of tin 21 which was formed by
electron beam vacuum deposition of tin onto a corona-treated
surface of a 75 gauge (about 19 micron) thermoformable oriented
polyethylene terephthalate film. Second metallized layer of
aluminum 22 may be formed as a continuous layer or a non-continuous
layer extending over first metallized layer of tin 21.
[0019] As depicted in FIG. 2, laminate 100 of container 10 still
further comprises a second substrate of thermoformable
thermoplastic substrate 12 which is applied over the second
metallized layer of aluminum 22. As previously mentioned, second
substrate 12 may be formed from any thermoformable thermoplastic
material which may include a monolayer sheet or multilayer film. In
one embodiment, substrate 12 is a sheet comprising homopolymers or
copolymers of polyethylene terephthalate, polyolefins including,
but not limited to, polyethylenes and polypropylenes, polystyrenes,
polyvinyl chlorides, cyclic olefins and blends thereof. In one
preferred embodiment, second thermoplastic substrate 12 comprises a
monolayer sheet or multilayer film of thermoformable polyethylene
terephthalate In another preferred embodiment, second thermoplastic
substrate 12 comprises a monolayer sheet or multilayer film of
thermoformable polystyrene. In still another preferred embodiment,
second thermoplastic substrate 12 is a black or opaque monolayer
sheet or multilayer film of thermoformable polyethylene
terephthalate, and more preferably, a black or opaque monolayer
sheet or multilayer film of amorphous thermoformable polyethylene
terephthalate. In an alternative preferred embodiment, second
thermoplastic substrate 12 is a black or opaque monolayer sheet or
multilayer film of thermoformable high-impact polystyrene. The
thickness of the second thermoplastic substrate 12 may also vary
depending upon the desired end-use. Typically, the thickness of
second thermoplastic substrate 12 is between 5 and 25 mil (127 and
635 micron) and preferably, between 10 and 20 mil (254 and 508
micron), more preferably. between 12 and 15 mil (304.8 and 381
micron), and most preferably about 13.25 mil (336.6 micron). It is
understood that in order to provide a black color and/or opaque
appearance, the polymer or polymer blends used to form second
thermoplastic substrate 12 may include dyes, fillers, pigments,
carbon black and the like. An example of a suitable commercially
available amorphous thermoformable polyethylene terephthalate is
Performance.TM. PET 1708HS supplied by StarPet, Inc. (Asheboro,
N.C.). A commercially available example of high-impact polystyrene
is Polystyrene 825E supplied by Total Petrochemicals USA, Inc. (La
Porte, Tex.).
[0020] Referring now to FIG. 3, there is illustrated an alternative
embodiment of laminate 200 which may be used to form container 10.
Laminate 200 comprises the same or similar monolayer films
described above for first thermoplastic substrate 11, first
metallized layer of tin 21, second metallized layer of aluminum 22,
and second thermoplastic substrate 12 for laminate 100, but further
includes an adhesive layer 13 which is in direct contact with the
second metallized layer of aluminum 22 and the second layer of
thermoplastic substrate 12. An example of a suitable commercially
available adhesive for use as adhesive layer 13 is SERFENE.TM. 2010
which is a polyvinylidene chloride (PVDC) emulsion adhesive system
supplied by Dow Chemical Company, Inc. (Midland, Mich.).
[0021] FIG. 5 illustrates another preferred embodiment of a
metallized laminate 300 of the present invention having a
multilayer first thermoformable thermoplastic substrate 11 and a
monolayer second thermoformable thermoplastic substrate 12.
Multilayer thermoformable thermoplastic substrate 11 may be formed
as a coextruded blown film comprising two or more film layers. In
this particular embodiment, substrate 11 is an eleven-layer film
structure having a first film layer 11a, a second film layer 11b, a
third film layer 11c, a fourth film layer 11d, a fifth film layer
11e, a sixth film layer 11f, and a seventh film layer 11g. First
film layer 11a may comprise polyethylene, preferably a blend of
ultra-low density polyethylene and linear low density polyethylene
and more preferably, a blend of about 87.7% by weight ultra-low
density polyethylene. about 10% by weight linear low density
polyethylene and about 2.3% by weight processing and antiblock
additives. An example of a suitable commercially available
ultra-low density polyethylene is ATTANE.TM. 4701G supplied by Dow
Chemical Company (Midland, Mich.). A commercially available example
of linear low density polyethylene is ExxonMobil.TM. 1001.32
supplied by ExxonMobil Chemical Company (Houston, Tex.). Film
layers 11b and 11f serve as a tie layer bonding layers ha to 11c,
and 11e to 11g, respectively. These layers may each comprise
anhydride-modified polyethylene. Preferably, layers 11b and 11f
each comprise a blend of anhydride-modified polyethylene and
polyethylene, more preferably, a blend of anhydride-modified
polyethylene and ultra-low density polyethylene, and most
preferably, a blend of between 10% and 70% by weight
anhydride-modified polyethylene and between 30% and 90% by weight
ultra-low density polyethylene. Examples of suitable commercially
available anhydride-modified polyethylene include Plexar.RTM. PX
3308 supplied by Equistar Chemicals, LP (Houston, Tex.) and
Bynel.RTM. 41E710 supplied by E. I. du Pont de Nemours and Company
(Wilmington, Del.). Film layers 11c and 11e serve as oxygen barrier
layers and may each comprise polyamide, preferably, a blend of
polyamides, more preferably, a blend of amorphous polyamide and
crystalline polyamide, and most preferably, a blend of about 15% by
weight amorphous polyamide and about 85% by weight of crystalline
polyamide. A suitable commercially available example of amorphous
polyamide is Grivory G21 supplied by EMS-Chemie (North America)
Inc. (Sumter, S.C.). An example of a suitable commercially
available crystalline polyamide is Ultramid.RTM. B36 01 supplied by
BASF Polyamides (Freeport, Tex.).
[0022] Substrate 11 of laminate 300 may further include a third
oxygen barrier layer 11d positioned between layers 11c and 11e.
Layer 11d may comprise an ethylene vinyl alcohol copolymer. The
final film layer of substrate 11 is layer 11g which serves as an
outer abuse layer and may comprise polyethylene terephthalate. An
example of a suitable commercially available polyethylene
terephthalate is Performance.TM. PET 1708 supplied by StarPet Inc.
(Asheboro, N.C.). In this embodiment, metallized laminate 300
further includes a first metallized layer of tin 21 deposited on a
corona-treated surface of film layer 11a, a second metallized layer
of aluminum 22 applied to tin layer 21, an adhesive layer 13 which
is in direct contact with the second metallized layer of aluminum
22 and the second layer of thermoplastic substrate 12. A suitable
adhesive material for use as adhesive layer 13 is a polyvinylidene
chloride (PVDC) emulsion adhesive system such as SERFENE.TM. 2010
supplied by Dow Chemical Company, Inc. (Midland, Mich.). Second
substrate 12 comprises a sheet of high-impact polystyrene having a
thickness approximately 20 mil (508 micron).
[0023] Turning now to FIG. 6, there is illustrated still another
preferred embodiment of a metallized laminate 400 of the present
invention having a monolayer first thermoformable thermoplastic
substrate 11 and a multilayer second thermoformable thermoplastic
substrate 12. Laminate 400 further includes a first metallized
layer of tin 21 deposited on a corona-treated surface of substrate
11, a second metallized layer of aluminum 22 applied to tin layer
21, an adhesive layer 13 which is in direct contact with the second
metallized layer of aluminum 22 and substrate 12. Substrate 11 may
comprise a transparent thermoformable film of biaxially oriented
polyethylene terephthalate. An example of a suitable commercially
available thermoformable oriented polyethylene terephthalate film
is 75 gauge Skyrol.RTM. SKC SL80C supplied by SKC, Inc. (Covington,
Ga.). Adhesive layer 13 may be any suitable material which bonds
comprise a polyvinylidene chloride (PVDC) emulsion adhesive system
such as SERFENE.TM. 2010 supplied by Dow Chemical Company, Inc.
(Midland, Mich.). As depicted, substrate 12 includes a first film
layer 12a, a second film layer 12b, a third film layer 12c, a
fourth film layer 12d, a fifth film layer 12e, a sixth film layer
12f, and a seventh film layer 12g. First film layer 12a comprises a
279.4 micron (11 mil) thick high-impact polystyrene such as
Polystyrene 825E supplied by Total Petrochemicals USA, Inc. (La
Porte, Tex.). Film layer 12b may comprise any adhesive which
adheres polystyrenes to polyolefins such as polyethylene. One such
adhesive is Avadyne.RTM. AV5210/CA500-83 supplied by Henkel
Corporation (Gulch Mills, Pa.). Film layer 12c includes
polyethylene, preferably, a blend of ultra-low density polyethylene
and linear low density polyethylene. In one preferred embodiment,
layer 12c includes a blend of about 64% by weight ultra-low density
polyethylene and about 35% by weight linear low density
polyethylene. Film layers 12d and 12f serve as tie layers bonding
layers 12c to 12e, and 12e to 12g, respectively, and may each
comprise anhydride-modified polyethylene. A suitable material for
use in layers 12d and 12f includes, but is not limited to,
LyondellBasell Plexar.RTM. PX3747 supplied by Lyondell Chemical
Company (Houston, Tex.). Layer 12e functions as an oxygen barrier
and preferably includes ethylene vinyl alcohol copolymer, The
seventh film layer 12g is a sealant layer capable of heat sealing
to another material having a similar chemical composition such as,
for example, a lidding film placed over recessed cavity 30. Film
layer 12g may comprise a polyolefin, including ethylene
homopolymers and copolymers such as polyethylene copolymer and
ethylene vinyl acetate copolymer. In a preferred embodiment, layer
12g comprises low density ethylene vinyl acetate copolymer having
5% vinyl acetate content. One such commercially available example
is LyondellBasell Petrothene.RTM. NA442051 supplied by Lyondell
Chemical Company (Houston, Tex.).
[0024] In FIG. 7, there is illustrated thermoformed laminate 200
having a cup or bowl shaped recessed cavity 30. As depicted, the
first substrate 11 serves as a first outer surface 33 of recessed
cavity 30, while second substrate 12 serves as a second outer
surface 34. In the forming operation, the laminate is shaped in a
manner such that at least a portion of the laminate undergoes an
extension or stretching in at least one dimension in order to form
a recessed cavity 30. Any conventional forming process may be used
for shaping the laminates of the present invention into its final
form. Exemplary forming processes include differential air pressure
thermoforming, vacuum forming, plug assist-vacuum forming, cold
rolling, draw forming, impact forming, hydroforming and the like.
An especially preferred conventional thermoforming process is one
where the plastic laminate is formed at a temperature of between
about 343.degree. C. and about 371.degree. C. (about 650.degree. F.
and about 700.degree. F.), In one embodiment, the laminates of the
present invention are thermoformed to provide a recessed cavity
having a draw depth of at least 0.635 centimeter (0.25 inch). In
another embodiment, the laminates of the present invention are
thermoformed to provide a recessed cavity having a draw depth of at
least 1.91 centimeter (0.75 inch).
[0025] Many modifications and other embodiments of the invention
set forth herein will come to mind to one skilled in the art to
which this invention pertains having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the invention is
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments disclosed to be included within
the scope of the appended claims. Although specific terms are
employed herein, they are used in a generic and descriptive sense
only and not for purposes of limitation.
* * * * *