Multilayer, high barrier laminate

A high barrier, multilayer laminate is disclosed that is suitable for forming packages that contain oxygen sensitive products. The laminate material has a coextruded multilayer material that includes from exterior to interior: i) an outside sealing and decorative layer, ii) a light barrier layer including an adhesive disposed interior to the outside sealing and decorative layer, iii) a barrier polymer layer disposed interior to the light barrier layer, iv) an oxygen scavenger layer including an adhesive disposed interior to the barrier polymer layer, and v) an inside sealing layer disposed interior to the oxygen scavenger layer. A further laminate structure suitable for forming a package containing an oxygen sensitive product is also disclosed. The further laminate includes a first layer of linear low density polyethylene, a carbon black layer including an adhesive disposed interior to the first layer of linear low density polyethylene; a layer of EVOH disposed interior to the carbon black layer, an oxygen scavenger layer including an adhesive disposed interior to the EVOH layer, and a second layer of linear low density polyethylene disposed interior to the scavenger layer.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
Not Applicable 
BACKGROUND OF THE INVENTION 
The present invention relates to a multilayer, high barrier laminate 
material. More specifically, the present invention relates to a 
multilayer, high barrier laminate material that includes an oxygen 
scavenging layer, wherein the laminate is particularly suitable for 
packaging oxygen sensitive products. 
Various packaged products are susceptible to degradation due to reactions 
with oxygen. The packaged products generally come into contact with the 
oxygen in two primary manners. First, the packaged product may not 
completely fill the container in which it is disposed thereby leaving a 
headspace. This headspace typically includes oxygen that may react with 
the packaged product resulting in the above-noted degradation. Second, the 
packaged product may come into contact with oxygen that diff-uses through 
the walls of the package from the ambient atmosphere. 
A number of approaches to inhibit exposure of the packaged product to 
oxygen are known. One such approach includes the provision of an oxygen 
scavenging sachet in the container. The sachet contains an oxygen 
scavenging material such as iron, iron oxide, or hydroxide. The oxygen 
scavenging material reacts with oxygen in the headspace of the container 
as well as with oxygen that diffuses through the walls of the container. 
Another approach relates to modifying the atmosphere within the container 
to effectively eliminate as much oxygen as possible from the container 
during the packaging process. This approach, however, neglects the fact 
that oxygen may permeate through the container walls after the packaging 
process is complete. 
Still another approach relates to the inclusion of an oxygen scavenging 
material in the walls of the package. Several patents relating to this 
approach include U.S. Pat. Nos. 5,021,515; 5,049,624; and 5,350,622. The 
structures disclosed in these patents are often difficult to manufacture. 
BRIEF SUMMARY OF THE INVENTION 
A high barrier, multilayer laminate is disclosed that is suitable for 
forming packages that contain oxygen sensitive products. The laminate 
material, which may be coextruded, comprises a multilayer structure 
including from exterior to interior: i) an outside sealing and decorative 
layer, ii) a light barrier layer including an adhesive disposed interior 
to the outside sealing and decorative layer, iii) a barrier polymer layer 
disposed interior to the light barrier layer, iv) an oxygen scavenger 
layer including an adhesive disposed interior to the barrier polymer 
layer, and (v) an inside sealing layer disposed interior to the oxygen 
scavenger layer. 
Other objects and advantages of the present invention will become apparent 
upon reference to the accompanying detailed description when taken in 
conjunction with the following drawings.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 illustrates one embodiment of the present laminate. As illustrated, 
the laminate includes a first multilayer structure 10 of a high barrier 
oxide layer 15 that is disposed interior to an exterior layer of biaxially 
oriented polyethylene terephthalate (PET) 20, that, for example, may have 
a thickness of about 1/2 mils or 12 microns. The high barrier oxide layer 
15 may have, for example, a thickness of several angstroms, depending on 
such desired attributes as the material stiffness and barrier properties. 
Alternatively, the high barrier oxide layer may be disposed exterior to 
the layer of biaxially oriented polyethylene terephthalate, as will be 
discussed below in connection with other embodiments. Given the light 
transmitting properties of the layers 15 and 20, the high barrier oxide 
layer 15 may carry a printed decoration, for example, on surface 17. 
Alternatively, the printed layer may be disposed on the surface of the 
layer of biaxially oriented polyethylene terephthalate adjacent the high 
barrier oxide layer 15. 
A second multilayer structure 25 includes an exteriorly disposed 
polyethylene layer 30, an oxygen scavenging layer 35 disposed interior to 
the polyethylene layer 30, and a further polyethylene layer 40 disposed 
interior to the oxygen scavenging layer 35 that, for example, forms the 
product contact layer. By way of example, the second multilayer structure 
25 may have a total thickness of between 50 microns and 100 microns. The 
first and second multilayer structures 10 and 25 are joined together in a 
wet or dry lamination process by an adhesive layer 45. 
The high barrier oxide layer 15 may be a layer of silicon oxide (SiOx), 
aluminum oxide (AlOx), or titanium oxide (TiOx). Layer 15 may be 
deposited, for example, using a plasma-enhanced chemical vapor deposition 
process or, alternatively, using a liquid phase or gaseous phase 
photo-chemical vapor deposition process. The layer 15 is, preferably, less 
than 500 D, and, even more preferably, between 50 D and 100 D. 
An economical apparatus and method for depositing a barrier layer on a 
substrate material is set forth in U.S. Ser. No. 08/527,414, filed Sep. 
13, 1995, which is hereby incorporated by reference. FIG. 2 illustrates 
one embodiment of the apparatus of that application. 
In accordance with the method and apparatus as applied to the present 
laminate structure, a continuous web of substrate material 50 is provided 
on which the barrier layer is to be deposited. The web may comprise the 
BOPET layer 20 alone or in laminated combination with the second 
multilayer structure 25. The web of substrate material is driven, either 
continuously or in an indexed fashion, through a reaction chamber 52 of a 
deposition apparatus 55 wherein there is provided a flow of precursor gas 
and oxidizer gas. The reaction chamber has an internal pressure of about 
one atmosphere. The continuous web of substrate material, the precursor 
gas, and the oxidizer gas are exposed to ultraviolet radiation in the 
reaction chamber as the continuous web of substrate material is driven 
therethrough to thereby provide the high barrier oxide layer on the web of 
substrate material. The method allows a continuous web of substrate 
material to be continuously processed at a reaction pressure of about one 
atmosphere thereby making the production of the resulting packaging 
material more economical than the batch processing at low pressure that is 
required of the prior processes. 
If a barrier layer of SiOx material is desired to be deposited on the web 
of substrate material, the precursor may be an organic silane such as 
tetraethoxysilane (TEOS), triethoxysilane, tetraacetoxysilane, or a 
siloxane such as hexamethyldisiloxane (HMDSO). Other silicon precursors 
may also be utilized, although organic silanes and organic siloxanes are 
preferable since they tend to be safer for use in large scale processing. 
The oxidizing gas may, for example, be an oxidizer such as N.sub.2 O or 
O.sub.2. The carrier gas may be an inert gas such as N.sub.2, Ar, or He. 
An aluminum based precursor is chosen if an aluminum oxide barrier is 
desired. 
Various polyethylene materials may be used as the polyethylene material of 
the second multilayer structure 25. The particular polyethylene chosen is 
dependent, among other things, on the particular contents that will be 
enclosed by the packaging material. For example, low density polyethylene 
is particularly well suited for use as the polyethylene of the second 
multilayer structure 25 where the packaged contents is a dry product, 
while linear low density polyethylene is particularly suitable for 
packaging liquid material. Other suitable polyethylenes include very low 
density polyethylene, high density polyethylene, ultra low density 
polyethylene, and metallocenes. 
The oxygen scavenger layer 35 comprises, preferably, the same polyethylene 
material as layers 30 and 40 and is compounded with an oxygen scavenging 
material in an amount between 0.1% and 99.9% of the total weight of the 
oxygen scavenger layer 35. The oxygen scavenging material may be selected 
from one or more materials including: an iron-based material; an organic 
compound; and/or a biologically active compound. Examples of iron based 
compounds include FeOx, pure iron, and Fe.sub.X O.sub.Z (OH).sub.T. Such 
iron-based materials allow the oxygen scavenging layer 35 of the disclosed 
laminate to be humidity activated at a time prior to or concurrent with 
the filling of a package formed from the laminate. For example, the 
laminate may be placed in an elevated temperature and humidity environment 
prior to or concurrent with the filling process for a predetermined time 
period sufficient to activate the iron-based material. Prior to such time, 
the laminate may be stored indefinitely in a place of relatively low 
humidity. A further, iron-based oxygen scavenger material suitable for use 
in the present laminate is a material known as OXYGUARD which is available 
from Toyo Seikan Kaisha of Yokohama, Japan. 
Various organic materials and compounds are also suitable for use in the 
oxygen scavenging layer 35, both singly and in combination. For example, 
ground sea grass and/or ground tea leaves may be suitable for use in the 
layer 35. A rice extract, such as disclosed in U.S. Pat. No. 5,346,697, 
may also be utilized. 
Monomers and short-chain polymers of, for example, polypropylene and/or 
polyethylene are likewise suitable. If a short chain polymer is used, 
selective activation of the oxygen scavenging layer 35 becomes possible by 
irradiating the laminate with, for example, ultraviolet light or with 
electron beam emissions. Such irradiation effects a cutting of the 
inter-monomer bonds thereby creating even shorter, and more chemically 
active, polymer chains and monomers. If acceleration of the oxygen 
scavenging process is desirable, the scavenging layer 35 may include both 
an organic material and an iron-based material. 
FIGS. 3 and 4 are flow diagrams illustrating embodiments of two methods of 
manufacturing the laminate of FIG. 1. As illustrated in FIG. 3, the first 
and second multilayer structures 10 and 25 may be constructed in separate 
processes. In one of these processes illustrated at step 60, the barrier 
oxide layer 15 is disposed on the surface of the BOPET layer 20 and an 
optional printing step 62 is performed to apply a decorative printing 
layer to the surface of the high barrier oxide layer 15 to thereby form 
the first multilayer structure 10. In a concurrent or time separated 
operation illustrated at step 65, the second multilayer structure 25 is 
formed by performing a three layer coextrusion of the outer PE layer 30, 
the oxygen scavenger layer 35, and the interior PE layer 40. The first and 
second multilayer structures 10 and 15 are then laminated together in a 
wet or dry lamination process illustrated at step 70. Execution of a wet 
lamination process is preferable. In instances in which a temperature 
sensitive oxygen scavenging material is used in layer 35. Wet lamination 
processes can generally be carried out at a lower temperature than dry 
lamination processes and are thus more applicable to uses in which one or 
more laminate components contains a temperature sensitive material. 
Various adhesives are suitable for joining the first and second multilayer 
structures 10 and 25. For example, a modified ethylene copolymer or a 
polyurethane adhesive may be used for this purpose. One polyurethane 
adhesive suitable for such use is sold under the name NC 253 A with 
co-reactant CA 3346 by Novacote International of Hamburg, Germany. One 
example of a modified ethylene copolymer is the anhydride functional LLDPE 
supplied by DuPont under the trade name of Bynel CXA. 
FIG. 4 illustrates a further exemplary embodiment of a method for 
manufacturing the laminate when the high barrier layer 15 is disposed 
exterior to the layer of BOPET 20. As illustrated in this example, the 
oxide barrier 15 is applied at step 75 after the three layer coextrusion 
has been laminated to the layer of BOPET 20. Additionally, an optional 
printing step 77 may be used to apply a decoration to the BOPET layer 
prior to lamination to the second, coextruded multilayer structure. Such 
printing may also take place after the lamination process, but before the 
high barrier oxide is applied. 
FIG. 5 illustrates a further laminate, similar to the sequence of layers 
set forth in FIG. 1, except that a layer of biaxially oriented 
polypropylene or polyamide 80 is utilized in place of the layer of BOPET. 
The laminate can be manufactured in the manner illustrated in FIGS. 3 and 
4, replacing the BOPET layer with the foregoing polypropylene or polyamide 
layer. The figure also illustrates the possibility of alternatively 
placing a high barrier oxide layer 15' exterior to the PP layer 80 as 
opposed to interior thereto. 
The laminate structure illustrated in FIG. 1 may be further joined to one 
or more additional layers at the exterior face of the high barrier oxide 
layer 15. Such additional layers are illustrated at 85 in FIG. 6 and may 
comprise, for example, paperboard, polyolefin, and/or foam layers joined 
to the oxide barrier layer 15. Alternatively, the additional layers may be 
joined to the BOPET layer 20 where the oxide barrier layer, as illustrated 
at 15', is disposed interior to the layer 20. The illustrated layers are 
joined by a suitable adhesive layer 90 in a lamination process. Such 
layers may likewise be joined to the structure of FIG. 5. 
A further laminate structure suitable for packaging oxygen sensitive 
products is illustrated in FIG. 7. In the illustrated embodiment, a layer 
of high barrier oxide material 15 (or 15') is disposed on an interior (or 
exterior) surface of a layer of BOPET 20, or, alternatively, BOPP, or 
BOPA. The resulting dual layer structure 10 is then laminated, using a wet 
lamination process, to a layer of PE 100. The PE material may be any one 
of the previously discussed polyethylene materials. The dual layer 
structure 10 and the PE layer 100 are joined using a layer of adhesive 105 
that includes very fine particulates of an oxygen scavenging material. The 
oxygen scavenging material can be any one or more of the materials noted 
above. The diameter of the oxygen scavenging particles is preferably less 
than 25 microns and, more preferably, less than 3 microns. This structure 
may also include additional layers, such as those discussed above in 
connection with FIG. 6. 
Any of the foregoing laminate structures are suitable for use in forming a 
pouch, or the like. One example of a pillow-type pouch 110 is illustrated 
in FIG. 8. When used to form the pouch 110, the laminate is sealed in a 
back-to-back manner so that the interior layers of PE are joined to one 
another about at least a portion of a perimeter portion 115. The present 
pillow pouch may be used to replace traditional structures typically 
having a structure of PET/adhesive/Al foil/adhesive/LLDPE, since the new 
laminates are less costly and are easier to manufacture, yet provide a 
structurally sound pouch that is substantially impervious to oxygen. 
FIG. 9 illustrates a further pouch 120, commonly known as the "Doy-Pak" 
type pouch. Such a pouch can be manufactured in accordance with the 
teachings of expired U.S. Pat. No. 3,502,521 and includes a gusseted 
bottom structure 123 and a flattened top portion 127. FIG. 10 illustrates 
a pouch 130 including both a gusseted bottom section 133 and a gusseted 
top section 137. Such pouch structures have a variety of uses. 
In systems for ambient temperature distribution of food, it is generally 
necessary to protect the food from three sources of degradation. These 
degradation sources include microbiological, oxygen and light. Aseptic 
systems based on H.sub.2 O.sub.2 combined with the use of aluminum foil 
are presently the most cost-effective solutions for dealing with these 
applications. However, an embodiment of a laminate structure suitable for 
use in forming a package that contains an oxygen sensitive product is 
illustrated in FIG. 11. 
The embodiment illustrated in FIG. 11 provides a material structure which 
can be used, for example, in forming flexible pouch or extrusion blown 
molded containers. Coextruded multilayer films, such as the one set forth 
herein offer a cost-effective way to produce materials that are 
heat-sealable and exhibit high barrier properties. Traditionally, the 
barrier performance and the cost of these films have not been competitive 
with aluminum foil because even the best barrier polymers do not function 
as an absolute barrier like aluminum foil. However, the addition of a 
light barrier layer and an oxygen scavenger layer makes the embodiment 
illustrated in FIG. 11 quite cost competitive with aluminum foil in the 
above-described applications while still providing high barrier 
properties. 
FIG. 11 illustrates an embodiment of the laminate having multiple layers. 
The layers may all be coextruded. For example, a product contact layer 140 
comprising a heat-sealable polymer is provided in the material structure. 
An adhesive and an oxygen scavenger are combined in a scavenger layer 142 
located exterior to the product contact layer 140. In addition, a barrier 
polymer layer 146 is located exterior to the scavenger layer 142. An 
adhesive and a light barrier material are located in a layer 148 disposed 
exterior to the barrier polymer layer 146. Finally, an outside sealing and 
decorative layer 152, which, for example, may include a color pigment, is 
located exterior to the light barrier layer 148. The outside sealing and 
decorative layer 152 is located at the outside of the material structure. 
Several different oxygen scavenging materials may be used in the oxygen 
scavenger layer 142. One such material is an ABPA additive available from 
Amoco. Another preferred oxygen scavenger material is AMOSORB available 
from Amoco. A typical amount of such an oxygen scavenger needed in the 
layer 142 to ensure the same barrier performance as aluminum foil for up 
to one year is typically 0.1-1 g/m.sup.2. Humidity is the trigger 
mechanism for such oxygen scavengers and makes it particularly suitable 
for containers for liquid foods. In addition, the barrier polymer layer 
146 may also contain some CaCO.sub.3 mineral filler to reduce the cost. 
FIG. 12 illustrates a further embodiment of the invention based on the 
structure of FIG. 11. In this embodiment, the product contact layer 140 is 
formed from LLDPE. The barrier layer 146 is formed from EVOH. In addition, 
the light barrier layer 148 includes carbon black. Finally, the outside 
sealing and decorative layer 152 is formed from LLDPE and includes 
TiO.sub.2 as the color pigment. 
Although the present invention has been described with reference to a 
specific embodiment, those of skill in the art will recognize that changes 
may be made thereto without departing from the scope and spirit of the 
invention as set forth in the appended claims.