U.S. patent application number 15/477492 was filed with the patent office on 2017-09-14 for packaging and method of making packaging.
The applicant listed for this patent is Prolamina Midwest Corporation. Invention is credited to Gary Knauf.
Application Number | 20170259546 15/477492 |
Document ID | / |
Family ID | 44307158 |
Filed Date | 2017-09-14 |
United States Patent
Application |
20170259546 |
Kind Code |
A1 |
Knauf; Gary |
September 14, 2017 |
PACKAGING AND METHOD OF MAKING PACKAGING
Abstract
Packaging and a method of making the packaging is disclosed. The
packaging includes a substrate with an asymmetrical coextrusion
attached there to. The coextrusion includes an ethylene vinyl
alcohol layer that is disposed toward the substrate.
Inventors: |
Knauf; Gary; (Bear Creek,
WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Prolamina Midwest Corporation |
Westfield |
MA |
US |
|
|
Family ID: |
44307158 |
Appl. No.: |
15/477492 |
Filed: |
April 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13521019 |
Oct 30, 2012 |
9610755 |
|
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PCT/US2011/021533 |
Jan 18, 2011 |
|
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15477492 |
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61296321 |
Jan 19, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 27/32 20130101;
B32B 29/002 20130101; B32B 2307/7248 20130101; B32B 27/308
20130101; Y10T 428/31743 20150401; B32B 27/16 20130101; B32B 27/306
20130101; B32B 2255/205 20130101; B32B 29/00 20130101; B32B 2439/70
20130101; B32B 27/34 20130101; B32B 2255/10 20130101; B32B 2307/546
20130101; B32B 27/08 20130101; B32B 27/28 20130101; Y10T 428/3192
20150401; B32B 27/36 20130101; Y10T 428/31855 20150401; B32B 7/12
20130101; Y10T 428/31895 20150401; B32B 27/327 20130101; Y10T
428/31928 20150401; B32B 2250/24 20130101; B32B 27/10 20130101;
B32B 2307/7244 20130101; B32B 27/322 20130101; B32B 2270/00
20130101; B32B 2255/26 20130101; Y10T 428/31797 20150401; Y10T
428/31909 20150401 |
International
Class: |
B32B 29/00 20060101
B32B029/00; B32B 27/08 20060101 B32B027/08; B32B 27/10 20060101
B32B027/10; B32B 27/36 20060101 B32B027/36; B32B 27/28 20060101
B32B027/28; B32B 27/32 20060101 B32B027/32; B32B 7/12 20060101
B32B007/12; B32B 27/30 20060101 B32B027/30; B32B 27/34 20060101
B32B027/34; B32B 27/16 20060101 B32B027/16 |
Claims
1. A packaging comprising: a substrate; and an asymmetrical
coextrusion attached to the substrate and including an ethylene
vinyl alcohol layer that is disposed toward the substrate.
2. The packaging of claim 1, further comprising a polymeric barrier
layer applied to at least one side of the substrate and wherein the
ethylene vinyl alcohol layer of the asymmetrical coextrusion is
attached to the polymeric barrier layer.
3. The packaging of claim 2, wherein the polymeric barrier layer is
low density polyethylene.
4. The packaging of claim 2, wherein the polymeric barrier layer
includes at least one of low density polyethylene, medium density
polyethylene, high density polyethylene, linear low-density
polyethylene, and metallocene catalyzed linear low density
polyethylene.
5. The packaging of claim 2, wherein the polymeric barrier layer
includes at least one of polypropylene, ethylene vinyl acetate
resin, IONOMER, nylon, ethylene acrylic acid copolymer (EAA),
ethylene methacrylic acid copolymer (EMAA), ethylene methyl
acrylate copolymer (EMAC), and ethylene n-butyl acrylate copolymer
(EnBA).
6. The packaging of claim 2, wherein a surface of the polymeric
barrier layer to which the ethylene vinyl alcohol layer is attached
is treated to promote attachment of the ethylene vinyl alcohol
layer to the polymeric barrier layer.
7. The packaging of claim 6, wherein the treatment is flame
treatment.
8. The packaging of claim 6, wherein the treatment is corona
treatment.
9. The packaging of claim 6, wherein the treatment is a liquid
primer.
10. The packaging of claim 1, wherein the substrate comprises
paper.
11. The packaging of claim 1, wherein the substrate comprises a
clear or metallized film selected from the group consisting of
polyethylene terephthalate, oriented polypropylene (OPP), nylon,
and polylactic acid (PLA) films.
12. The packaging of claim 1, wherein the asymmetrical coextrusion
further includes a tie resin and a sealant.
13. The packaging of claim 12, wherein the tie resin and the
sealant are blended together to form a tie sealant resin blend.
14. The packaging of claim 13, wherein the asymmetrical coextrusion
is a two layer coextrusion including the ethylene vinyl alcohol
layer and a tie sealant resin blend layer.
15. The packaging of claim 14, wherein the asymmetrical coextrusion
is formable using a two resin capable coextruder.
16. The packaging of claim 12, wherein the asymmetrical coextrusion
includes the ethylene vinyl alcohol layer, a tie resin layer, and a
sealant layer and wherein the tie resin layer is disposed between
the ethylene vinyl alcohol layer and the sealant layer.
17-33. (canceled).
34. A packaging comprising: a substrate; and an asymmetrical
coextrusion attached to the substrate and including an ethylene
vinyl alcohol layer and at least one support layer; the ethylene
vinyl alcohol layer is disposed toward the substrate and having a
first face and a second face, wherein the first face directly
contacts the at least one support layer and wherein the second face
does not directly contact any other layer of the asymmetrical
coextrusion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a divisional application of U.S.
National Stage application Ser. No. 13/521,019, filed on Oct. 30,
2012, now U.S. Pat. No. 9,610,755, which claims priority to
International patent application number PCT/US2011/021533, filed on
Jan. 18, 2011, which, in turn, claims priority to U.S. provisional
patent application Ser. No. 61/296,321 titled "Packaging Materials"
and filed on Jan. 19, 2010. The full contents of each of the
aforementioned applications is incorporated by reference as if set
forth in its entirety herein.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not applicable.
TECHNICAL FIELD
[0003] This disclosure relates to packaging and, in particular, to
layered packaging for food or other items in which freshness is to
be maintained.
BACKGROUND OF THE INVENTION
[0004] Flexible packaging, particularly for food, is subject to
many demands. The packaging needs to be workable in such a way that
the packaging material may be quickly placed around the item to be
packaged using machinery. The packaging material must also be of
such a quality that it adequately stores the product before the
packaging is open. In the case of food products, this typically
means that the packaging materials provide an oxygen barrier to
maintain freshness.
[0005] Ethylene vinyl alcohol (EVOH) is an extrudable resin that
has excellent oxygen, flavor, and aroma barrier properties. EVOH
resins and packaging materials have been used for several decades
as meat and cheese film wrappers and the barrier properties of EVOH
with respect to oxygen, grease, oil, flavor additives, and aroma is
well understood.
[0006] However, when exposed to humidity levels of 85% or higher,
the barrier properties of EVOH degrade. To avoid this degradation,
the EVOH is typically extruded in a multi-layer symmetrical
coextrusion in which specialized tie resins are used to adhere the
EVOH to outer polyolefin layers that protect the EVOH from
humidity. For example, a three resin, five layer coextrusion of
EVOH may include LDPE-Tie Resin-EVOH-Tie Resin-LDPE. In this five
layer structure, the LDPE (low density polyethylene) layers protect
the EVOH layer from exposure to moisture. Also, the LDPE and Tie
Resin are extruded each from one extruder where they are split into
two layers and directed to either side of the EVOH layer by a
feedblock device. The LDPE and Tie Resin are exactly the same
material on both sides of the EVOH, thus it is called a symmetrical
coextrusion.
[0007] It should be further understood that, when melted, EVOH
becomes fluid very quickly with very low melt strength and cannot
be extruded as a separate thin film. In extrusion coating, a melt
curtain is formed between the exit of the extruder die and the
extruder nip. The melt curtain is completely unsupported in this
air gap between the die and the extruder nip. Therefore, the melt
curtain needs to have enough viscosity and melt strength to keep
from tearing apart. Thus, EVOH has traditionally required the
above-described five layer structure not only to maintain its
barrier properties, but also to provide adjacent structural layers
(such as polyethylene (PE)) that physically support the coextruded
layer of the EVOH. Thus, while EVOH has excellent oxygen barrier
properties, EVOH has been considered unsuitable as a barrier layer
in some applications for a number of reasons. For one, production
of EVOH has required extrusion machines capable of coextruding more
than two resins. Such machines are very expensive and not as common
as those extruding only two resins. Further, dual tie resin and
polyolefin layers are provided on both sides of the EVOH
coextrusion to protect the EVOH layer from humidity; however, these
multiple layers can increase the material cost of the packaging and
increase the thickness of the packaging. This has made EVOH-based
packaging less competitive for certain packaging applications.
[0008] Hence, there is a continuing need for improved and lower
cost EVOH packaging and a method of making the same.
SUMMARY OF THE INVENTION
[0009] Packaging for food and a method of making the packaging is
disclosed. This packaging incorporates an EVOH layer which serves
as an oxygen barrier to the surrounding environment. However, the
packaging does not include the symmetrical five layer coextruded
structure heretofore believed to be necessary both to support an
EVOH layer and to further protect this EVOH layer from moisture
which can compromise its effectiveness. Moreover, in some forms,
the packaging can be formed using a standard two resin capable
coextruder station which reduces the cost of fabricating the
packaging--in comparison to the traditional five layer structure
using a three resin coextruder station.
[0010] The packaging includes a substrate and an asymmetrical
coextrusion attached to the substrate. The asymmetrical coextrusion
includes an ethylene vinyl alcohol layer that is disposed toward
the substrate.
[0011] In some preferred forms, the packaging may further include a
polymeric moisture barrier layer applied to at least one side of
the substrate. The ethylene vinyl alcohol layer of the asymmetrical
coextrusion may be attached to the polymeric barrier layer. The
polymeric barrier layer may be a polymeric moisture barrier layer
and be used to protect one side of the ethylene vinyl alcohol from
exposure to moisture in the packaging. This polymeric barrier layer
may include any of a number of materials including low density
polyethylene, medium density polyethylene (MDPE), high density
polyethylene (HDPE), linear low-density polyethylene (LLDPE),
metallocene catalyzed linear low density polyethylene (mLLDPE),
polypropylene (PP), ethylene vinyl acetate (EVA) resin, IONOMER,
Nylon, ethylene acrylic acid copolymer (EAA), ethylene methacrylic
acid copolymer (EMAA), ethylene methyl acrylate copolymer (EMAC),
and ethylene n-butyl acrylate copolymer (EnBA). This polymeric
barrier layer may also include additives such as colorants, EVOH
tie resin, and fillers such as calcium carbonate. This polymeric
barrier layer may also include blends or multilayered coextrusions
of the above listed materials. This polymeric barrier layer is not
extruded from any materials used in the asymmetrical EVOH
coextrusion.
[0012] A surface of the polymeric barrier layer to which the
ethylene vinyl alcohol layer is attached may be treated to promote
attachment of the ethylene vinyl alcohol layer to the polymeric
barrier layer. For example, the treatment may be a flame treatment,
liquid priming, or a corona treatment.
[0013] In some forms, the substrate may include paper or another
cellulosic material. In other forms, the substrate may be a clear
or metallized film selected from a group consisting of polyethylene
terephthalate (PET), polypropylene, nylon, and PLA (polylactic
acid) films. Additionally, the substrate may be a lamination of
paper and clear or metallized film substrates listed above.
[0014] In addition to the ethylene vinyl alcohol layer, the
asymmetrical coextrusion may further include a tie resin and a
sealant. In one form, the tie resin and the sealant may be blended
together to form a tie sealant resin blend. In this form, the
asymmetrical coextrusion may be a two layer coextrusion including
the ethylene vinyl alcohol layer and a tie sealant resin blend
layer which is formable using a two resin capable coextruder. In
another form, the asymmetrical coextrusion may include the ethylene
vinyl alcohol layer, a tie resin layer, and a sealant layer. The
tie resin layer may be disposed between the ethylene vinyl alcohol
layer and the sealant layer forming a three layer asymmetrical
coextrusion.
[0015] Additionally, a method of making the packaging of the type
described above is disclosed. In this method, a substrate is
provided and an asymmetrical coextrusion including an ethylene
vinyl alcohol layer is extruded. The ethylene vinyl alcohol layer
of the asymmetrical coextrusion is attached to the substrate to
form the packaging.
[0016] The method may further include the step of applying a
polymeric barrier layer to at least a portion of at least one side
of the substrate before attaching the ethylene vinyl alcohol layer
of the asymmetrical coextrusion to the substrate to form the
packaging. The ethylene vinyl alcohol layer may be directly
attached to the polymeric barrier layer. The polymeric barrier
layer could be made of low density polyethylene or one or more of
the materials listed above.
[0017] The method may further include the step of treating a
surface of the polymeric barrier layer prior to attaching the
ethylene vinyl alcohol layer of the asymmetrical coextrusion to the
substrate to form the packaging. Treating promotes adhesion between
the polymeric barrier layer and the ethylene vinyl alcohol layer.
This treatment may be, for example, a flame treatment, liquid
priming, or a corona treatment.
[0018] As mentioned and listed above, both the substrate and the
coextrusion may be made of various materials and/or blends of
materials.
[0019] The foregoing and still other advantages of the invention
will appear from the following description. In that description
reference is made to the accompanying drawings which form a part
hereof and in which there is shown by way of illustration preferred
embodiments of the invention. These embodiments do not represent
the full scope of the invention. Rather, the claims should be
looked to in order to judge the full scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIGS. 1 through 3 illustrate the layer structure of the
three exemplary embodiments of the packaging; and
[0021] FIG. 4 illustrates an exemplary process line which may be
used to make or fabricate the packaging.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Disclosed below are structures for a packaging containing
EVOH which do not require complex coextrusion machinery
configurations capable of forming five layer coextrusions. As used
herein, a "-" is used to indicate layers that are coextruded with
one another and "/" is used to indicate layers that are separated
attached to one another.
[0023] Now with reference to FIGS. 1 through 3, a number of
packaging structures are illustrated including: [0024] (1)
PAPER/LDPE/EVOH-TSRB [0025] (2) PAPER/LDPE/EVOH-TIE-SEALANT [0026]
(3) PET FILM/LDPE/EVOH-TSRB As used herein, TSRB refers to a tie
resin and sealant resin blend in which the tie resin and sealant
are blended together such that the blend may be coextruded as a
single layer, whereas EVOH-TIE-SEALANT refers to three discrete
separately formed layers of EVOH, tie resin (which is a type of
resin designed to adhere the EVOH and the sealant layers together),
and sealant. With respect to the figures, like reference numerals
are used to describe like items in which the hundreds digit has
been increased to correspond to the figure number (e.g., TSRB layer
110 corresponds to TSRB layer 310).
[0027] Looking first at FIG. 1, the layers of structure (1) listed
above are illustrated. In FIG. 1, a packaging 100 includes a paper
substrate 102 with a polymeric barrier layer 104 coating one side
thereof and an asymmetrical coextrusion 106 having an ethylene
vinyl alcohol layer 108 and a TSRB layer 110. The ethylene vinyl
alcohol layer 108 of the coextrusion 106 is directly attached to
the polymeric barrier layer 104 along a polymeric barrier
layer--ethylene vinyl alcohol layer interface 112 such that the
TSRB layer 110 on the opposite side of the coextrusion 106
constitutes one of the outer surfaces of the packaging 100. The
exposed TSRB surface could be contacted with another exposed TSRB
surface and subjected to heat and pressure to form a seal there
between.
[0028] It is contemplated that the paper substrate may be a paper
of a type having a machine glazed (MG) or a machine finished (MF)
type finish, may be clay coated paper, may be of a white or a
natural color, and may be of a Kraft, ground wood, recycled, or
sulfite furnish. The paper may include laminations of one or more
layers of paper or include a clear or metallized PET, oriented
polypropylene (OPP), Nylon, or PLA film laminated to the paper.
[0029] In one preferred form, the polymeric barrier layer is low
density polyethylene (LDPE). However, the polymeric barrier layer
on the paper may alternatively be MDPE, HDPE, LLDPE, POP
(polyolefin plastomer), mLLDPE, or blends thereof as well as
coextrusions thereof. Additives such as colors can be used. Other
resins can be used in place of LDPE such as PP, EVA, IONOMER,
Nylon, EAA, EMAA, EMAC, EnBA, and the like. If needed, EVOH tie
resin can be blended into the poly layer for improved adhesion,
especially if PP or HDPE is used in place of LDPE. In all cases,
the materials used for the polymeric barrier layer are not extruded
from the extruders used to make the asymmetrical EVOH
coextrusion.
[0030] To ensure good adhesion, the paper and/or polymeric barrier
layers may be subjected to flame treatment, corona treatment, or
other such priming to ready the surfaces for attachment.
[0031] With respect to the specific chemical composition of the
layers, the ethylene vinyl alcohol may be 35 mol % ethylene EVOH
(available as EVAL C109B from Eval Company of America) and the TSRB
may be 50% POP (polyolefin plastomer, available as DOW PT1450 from
Dow Chemical Company), 25% tie resin (such as ADMER AT1000A
available from Mitsui Chemicals America, Inc.), and 25% LDPE
(low-density polyethylene, available as CHEVRON 1013 available from
Chevron Chemical). The exact percentages of the constituent
components may be varied depending on the temperatures, times, and
pressures used to form the heat seal and the quality of the seal
desired. Although EVOH with 35 mol % or higher ethylene content is
believed to provide the best results, EVOH is available in 24%
ethylene to 48% ethylene content. It is contemplated that any
amount of ethylene content might be used or selected based on the
desired properties of the barrier or for appropriate economy.
Generally speaking, the lower the ethylene content, the better the
aroma and oxygen barrier provided by the EVOH layer. It is
contemplated that the basis weight of the EVOH layer may be in the
range of 0.1#/3,000 ft.sup.2 to 10.0#/3,000 ft.sup.2.
[0032] The TSRB may have a tie resin content from 10 wt % to 80 wt
% and a polyethylene content from 20 wt % to 90 wt %. The tie resin
may be an anhydride modified LDPE based adhesive resin concentrate
such as ADMER AT1000A or DUPONT BYNEL 41E170. The polyethylene
sealant resin may be LDPE, MDPE, HDPE, LLDPE, POP, mLLDPE and
blends thereof, and copolymers of polyethylene such as, for
example: EVA, IONOMER, EAA, EMAA, EMAC, EnBA, and the like. TSRB
can be further modified with slip, antiblock, or color concentrates
depending upon customer needs.
[0033] The particular tie sealant resin blend selected may be
configured to maximize the quality of the seal. The basis weight of
the TSRB layer may be in the range of 1.0#/3,000 ft.sup.2 to
30.0#/3,000 ft.sup.2 and modified to provide enough TSRB material
to form a robust seal.
[0034] In order to achieve a thin and stable coating layer, EVOH is
not extrusion coated as its own single layer, but can be coextruded
with the TSRB or, as will be described with respect to structures
(2) and (3) below, the tie resin and sealant layers. Of course, a
benefit of using the tie sealant resin blend as in structures (1)
and (3) is that a three resin capable coextruder is not required,
but a two resin capable coextruder will be sufficient. In contrast,
standard three resin, five layer EVOH extrusion coating production
would require a more complex and costly coextruder, and add sealant
and tie resin layers to the inside of the EVOH layer which have
been rendered unnecessary by the inclusion of the polymeric barrier
coating on the substrate which serves as a moisture barrier on that
side of the EVOH layer.
[0035] Turning now to FIG. 2, structure (2), designated 200, is
illustrated which is similar to structure (1), but in which the
TSRB layer 110 of the asymmetrical coextrusion 106 has been
replaced by separate tie resin and sealant layers 214 and 216,
respectively. The paper substrate (202), polymeric barrier layer
(204), and the interface (212) between the polymeric barrier layer
and the ethylene vinyl alcohol layer are as described above. This
means that the asymmetrical coextrusion 206 is a three layer
coextrusion with the tie resin layer 214 sandwiched between the
ethylene vinyl alcohol layer 208 and the sealant layer 216. This
configuration eliminates any tie and sealant resin layers between
the EVOH and substrate. Accordingly, the sealant layer 216 is
disposed such that it is on an attachment face (i.e., the face that
will be attached to another face of the packaging) when the
packaging is heat sealed.
[0036] Now with reference to FIG. 3, the structure (3), designated
300, listed above is illustrated. Structure (3) is similar to
structure (1), except that the paper substrate 102 has been
replaced with a clear polyethylene terephthalate (PET) film
substrate 302. The polymeric barrier layer (304), asymmetrical
coextrusion (306), ethylene vinyl alcohol layer (308), TSRB layer
310 and the interface (312) between the polymeric barrier layer and
the ethylene vinyl alcohol layer are as described above. According
to this form, the polymeric barrier layer 304 coats at least a
portion of one side of the PET film substrate 302.
[0037] In alternative forms, the PET film in structure (3) might
alternatively be any kind of clear or metalized polyethylene
terephthalate, polypropylene, nylon, or PLA (polylactic acid)
film.
[0038] Looking at the structures (1)-(3) above, it can be seen that
the EVOH coextrusion is asymmetrical in all forms, unlike the
LDPE-Tie Resin-EVOH-Tie Resin-LDPE structures which have been
previously produced. Now, when extruded, the EVOH layer is
initially at least partially exposed with one side of the layer
being supported and protected by either the tie sealant resin blend
layer or the tie resin and sealant layers. As will be described in
more detail below with respect to the method of making the
packaging, this initially exposed side of the EVOH layer is
attached or laminated to the substrate, or polymeric barrier
coating thereon, such that this exposed face is no longer
exposed.
[0039] It should be appreciated that in all three structures (1)
through (3), the initially-exposed face of the EVOH layer is
attached to a polymeric barrier layer which helps to protect that
side of the EVOH layer from moisture. While this polymeric barrier
layer is preferable for many applications, it is also contemplated
that the polymeric barrier layer may be eliminated and the EVOH
layer directly attached to the paper substrate or PET film
substrate. To some extent, the removal of the polymeric barrier
layer will increase the exposure of the EVOH layer to moisture
which increases the rate of oxygen or aroma transmission through
the EVOH layer. However, the PET film substrate may, at least to
some degree, serve as a moisture barrier. Accordingly, by
increasing either the substrate thickness and/or the EVOH layer
thickness, the integrity of the product may be preserved for a
longer period of time, even in the absence of the polymeric barrier
layer. If the product to be housed in the packaging does not
require good moisture vapor barrier, then it may be acceptable to
remove the polymeric barrier layer.
[0040] These structures provide a number of advantages over known
flexible packaging solutions. In applications where a moderate
oxygen barrier is required, EVOH provides good oxygen barrier at a
lower cost than Al foil, metallized PET (MPET) film, and PVDC
(polyvinylidene chloride) coated PET or OPP films. Further, for
those applications which previously included PVDC in the packaging
materials as a barrier material, the EVOH replaces the PVDC coated
flexible packaging materials with a product that can be incinerated
without worries of producing hydrochloric acid or other chlorinated
hydrocarbon fumes into the air.
[0041] In one preferred form for the packaging, the packaging has a
structure of 25#PAPER/10#LDPE/4#EVOH-7#TSRB. (#/ream is based on a
3,000 ft.sup.2 ream size) The paper basis weight can range from
9#/ream to 100#/ream. The paper may be Kraft paper with a machine
glaze type finish and of bleached white color which may be flame
treated for good adhesion of the LDPE to the paper. The LDPE may be
corona treated for good adhesion of the EVOH coextrusion to the
LDPE coated paper. The LDPE for the polymeric layer (Chevron 4517)
would be of slightly higher density than the LDPE used in the TSRB
(Chevron 1013). This will provide improved moisture barrier for
protection of the EVOH, while the LDPE used in the TSRB would be
optimized for heat seal properties. The EVOH in the 4#EVOH-7#TSRB
coextrusion is 35 mol % ethylene EVOH. However, for other
applications the composition of the TSRB in the coextrusion may be
tweaked. In this form, the TSRB may be 25% tie resin (ADMER
AT1000A) and 75% LDPE (CHEVRON 1013). Even though a LDPE layer is
present between the paper and the EVOH, it should be appreciated
that the EVOH-TSRB coextrusion is formed from a single die and this
part of the structure does not require more than a two resin
coextruder station.
[0042] Some specific additional variations are provided below with
respect to the disclosed structures. According to one form, the
structure of the packaging material is
25#PAPER/10#LDPE/4#EVOH-1.5#TIE-5.5# PE SEALANT. In another form,
the structure of the packaging material is
25#PAPER/10#LDPE/1#TIE-4#EVOH-1#TIE-5# PE SEALANT to introduce a
tie layer between the EVOH and the LDPE deposited on the paper.
Similarly, the type of polyethylene in the polymeric layer can be
different than the LDPE used in the sealant and the thickness of
the LDPE layer can be independently adjusted to optimize product
performance.
[0043] Now with reference to FIG. 4, a line 400 for making the
packaging is disclosed. The line 400 illustrated is suitable for
making any of the structures (1)-(3) listed above. One of ordinary
skill in the art will readily appreciate, however, that segments of
the line 400 may be eliminated or not used based on the desired
structure of the final product.
[0044] The line 400 includes two sections. The first section forms
a coated substrate including the paper or PET layer with the
polymeric barrier layer coated there on. The second section then
applies the EVOH coextrusion to the coated substrate.
[0045] In the form shown, the first section of the line 400
prepares the substrate, which may be, for example, the paper or PET
film substrate. The substrate is unrolled from a main substrate
roll 402 and fed toward an extrusion coater 406 which coats the
substrate with the polymeric barrier layer.
[0046] On the way to the extrusion laminator 406, the substrate
from the main substrate roll 402 is fed past a treater 404 such as
a flame treater or a corona treater that treats the surface of the
substrate from the main substrate roll 402 such that the polymeric
barrier layer created at the extrusion coater 406 will adhere well
to the substrate. A liquid primer might also be applied to treat
the surface. Although treatment of the substrate is depicted, it
should be appreciated that such treatment is not required and some
substrate materials may not need treatment prior to application of
the polymeric barrier layer.
[0047] At the extrusion coater 406, the substrate is fed through a
nip point at which point the polymeric barrier layer is applied on
the substrate as a melt curtain. The nip point occurs between a
rubber nip roll 408 and a chill roll 410. As the substrate
approaches the nip point, at a location above the nip point, a die
412 supplies a molten resin A (which may be, for example, low
density polyethylene or any of the polymeric barrier materials
listed above) as a melt curtain. This molten resin A is applied to
a top surface of the substrate at the nip point, is cooled by the
chill roll 410 to form a substrate/polymeric barrier layer
structure, and then this coated substrate exits the extrusion
coater 406.
[0048] It should be appreciated that while the line 400 is shown
including the extrusion coater 406 for the formation of the
substrate/polymeric barrier layer structure, that if the
coextrusion is to be directly applied to the paper that the
extrusion coater station may be eliminated. Further, it is possible
that the substrate could be coated by the polymeric barrier layer
using methods other than an extrusion coater. For example, a spray
coating could be applied to the paper or PET substrate.
[0049] In any event, the substrate may be optionally fed past a
treater 414 that treats the surface of the substrate for better
adhesion to the coextrusion further down the line 400. Again, the
treater 414 may incorporate a flame treatment, liquid priming, or a
corona treatment to prepare the surface of the substrate.
[0050] In the second portion of the line 400, a coextrusion coater
416 applies or coats the substrate with the EVOH coextrusion to
form the packaging. In the coextrusion coater 416, the substrate is
fed between a rubber nip roll 418 and a chill roll 420. A feedblock
422 of the coextruder 424 receives molten EVOH and at least one
other molten resin B and/or C. If an EVOH-TSRB coextrusion is being
formed, then the molten TSRB is also fed into the feedblock 422 (as
B, with no C resin being fed) and a two layer coextrusion of
EVOH-TSRB is extruded by the die 426 proximate the nip point such
that the EVOH layer side contacts the paper substrate. In this
form, the coextruder 424 may be only a two resin capable coextruder
(i.e., the coextruder 424 does not need to be capable of receiving
or extruding a molten resin C). If an EVOH-Tie-Sealant coextrusion
is being formed, then in addition to the molten EVOH, the feedblock
422 receives both a molten tie resin (as B) and a molten sealant
(as C) and the die 426 extrudes an EVOH-Tie-Sealant coextrusion
such that the EVOH layer is applied to the substrate and laminated
to the substrate at the nip point. After exiting the coextrusion
coater 416, the packaging is wound up on a product wind-up roll
428.
[0051] While specific embodiments of the present invention has been
shown, various modifications falling within the breadth and scope
of the invention will be apparent to one skilled in the art. Thus,
the following claims should be looked to in order to understand the
full scope of the invention.
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