U.S. patent application number 11/023715 was filed with the patent office on 2005-05-26 for multilayered plastic container.
This patent application is currently assigned to PLASTIPAK PACKAGING, INC.. Invention is credited to Darr, Richard C., Slat, William A..
Application Number | 20050112308 11/023715 |
Document ID | / |
Family ID | 29740274 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050112308 |
Kind Code |
A1 |
Darr, Richard C. ; et
al. |
May 26, 2005 |
Multilayered plastic container
Abstract
A three or more layered plastic container is provided, wherein
the innermost first layer is a plastic layer, the intermediate
second layer is a plastic layer adjacent the first layer containing
an oxygen scavenging material, and the outermost third layer is a
plastic layer. The thickness of the innermost layer is in the range
of 0.1 to 3 mils and is controlled based on the desired shelf life
of the container in the unfilled condition.
Inventors: |
Darr, Richard C.; (Medina,
OH) ; Slat, William A.; (Brooklyn, MI) |
Correspondence
Address: |
ROBERT H. BACHMAN
59 RICHARD SWEET DRIVE
WOODBRIDGE
CT
06525
US
|
Assignee: |
PLASTIPAK PACKAGING, INC.
|
Family ID: |
29740274 |
Appl. No.: |
11/023715 |
Filed: |
December 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11023715 |
Dec 28, 2004 |
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10461623 |
Jun 13, 2003 |
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60392006 |
Jun 25, 2002 |
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Current U.S.
Class: |
428/35.7 |
Current CPC
Class: |
B29K 2995/0067 20130101;
B29K 2067/00 20130101; B29B 11/08 20130101; B65D 1/0215 20130101;
Y10T 428/1352 20150115; B29K 2081/06 20130101; B29B 2911/14093
20130101; B32B 27/08 20130101; B29B 2911/14053 20130101; B29B
2911/14066 20130101; B29K 2023/086 20130101; B29K 2067/006
20130101; B32B 2305/70 20130101; B29K 2023/12 20130101; B32B
2307/74 20130101; B29K 2025/00 20130101; B29B 2911/1444 20130101;
B29K 2027/06 20130101; B29B 2911/14646 20130101; B65D 81/266
20130101; B29B 2911/14133 20130101; B29K 2055/02 20130101; B29K
2027/18 20130101; B29L 2031/7158 20130101; B29K 2023/06 20130101;
B32B 2272/00 20130101; B29K 2069/00 20130101; B29B 2911/1412
20130101; B29K 2105/26 20130101; B29B 2911/14166 20130101; B29B
11/14 20130101; B29K 2077/00 20130101; B29B 2911/14466 20130101;
B32B 37/153 20130101; B29B 2911/1408 20130101; B29B 2911/14333
20130101; B29B 11/10 20130101; B29K 2105/258 20130101 |
Class at
Publication: |
428/035.7 |
International
Class: |
B65D 001/00 |
Claims
What is claimed is:
1-12. (canceled)
13. The process which comprises: forming a multilayered plastic
container having an upper wall portion, an intermediate sidewall
portion and a self-supporting base portion, said portions formed
from at least an innermost first layer, an intermediate second
layer and an outermost third layer; and wherein said innermost
first layer is formed from a plastic material having a thickness of
from 0.1 to 3 mils, said intermediate second-layer is formed from a
plastic material containing at least one oxygen scavenging material
and having a thickness of from 0.1 to 3 mils, and said outermost
third layer is formed from a plastic material having a thickness of
from 3 to 23 mils.
14. The process according to claim 13, including forming the
innermost first layer from a plastic material approved for contact
with food or beverage products, and controlling the thickness of
the innermost first layer in the range of 0.1 to 3 mils based on
the desired shelf life of the container in the unfilled
condition.
15. The process according to claim 13, including the step of
forming a blow molded container.
16. The process according to claim 13, including forming said
container from a multilayered preform, including forming extrusion
molded innermost and intermediate layers and an injection molded
outermost layer.
17. The process according to claim 13, including providing at least
5% of recycled plastic material in the outermost layer.
18. The process according to claim 13, including providing that the
outermost layer comprises at least 40% by weight of the total
weight of the container.
19. The process according to claim 13, including providing that the
intermediate layer contains a barrier material.
20. The process according to claim 13, including providing that at
least one layer has differing thicknesses.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on Provisional U.S. Patent
Application Ser. No. 60/392,006, filed Jun. 25, 2002.
TECHNICAL FIELD
[0002] The present invention relates to multi-layered containers.
More particularly, the present invention relates to blow molded
multi-layered plastic containers.
BACKGROUND ART
[0003] Multi-layered plastic containers are commonly used for
packaging items in a wide range of fields, including food and
beverage, medicine, health and beauty, and home products. Plastic
containers are known for being easily molded, cost competitive,
lightweight, and generally suitable for many applications.
Multi-layered containers provide the added benefit of being able to
use different materials in each of the layers, wherein each
material has a specific property adapted to perform a desired
function.
[0004] Because plastic containers may permit low molecular gases,
such as oxygen and carbon dioxide, to slowly permeate through their
physical configurations, the use of plastic containers sometimes
proves to be less desirable when compared to containers formed from
other less permeable materials, such as metal or glass. In most
applications, the shelf life of the product contents is directly
related to the package's ability to effectively address such
molecular permeation. In the case of carbonated beverages, such as
beer, oxygen in the atmosphere surrounding the container can
gradually permeate inwardly through the plastic walls of the
container to reach inside of the container and deteriorate the
contents. Likewise, carbon dioxide gas associated with the contents
may permeate outwardly through the plastic walls of the container
until eventually being released on the outside, causing the
carbonated beverage to lose some of its flavor and possibly become
"flat".
[0005] To address some of the foregoing concerns, plastic container
manufacturers have utilized various techniques to reduce or
eliminate the absorption and/or permeability of such gases. Some of
the more common techniques include: increasing the thickness of all
or portions of the walls of the container; incorporating one or
more barrier layers into the wall structure; including
oxygen-scavenging or reacting materials within the walls of the
containers; and applying various coatings to the internal and/or
external surface of the container. However, a number of
conventional barrier and/or scavenger materials will not
effectively curtail the permeation of both oxygen and carbon
dioxide over extended periods of time. Moreover, there are usually
other practical concerns associated with most conventional
techniques, most commonly, increased material costs and/or
production inefficiencies.
[0006] In recent times, the use of plastics has become a
significant social issue. Recycling has become an increasingly
important environmental concern and a number of governments and
regulatory authorities continue to address the matter. In a number
of jurisdictions, legislation pertaining to minimum recycled
plastic content and the collection, return, and reuse of plastic
containers has either been considered or has already been enacted.
For example, in the case of plastic containers used to hold
consumable items, such as food items or beverages, regulations
often require a certain content and minimum thickness of FDA
approved material for the innermost layer that comes in contact
with the contents. Conventional processes, such as co- or
multiple-injection molding, are often limited as to the amount of
recycled plastic that can be effectively incorporated into the
structure of the container due to process limitations. Commonly,
the amount of recycled content that can be effectively incorporated
into conventional co-injection molded containers that are suitable
for food contents is less than 40% of the total weight of the
container.
[0007] Therefore, a need exists in the industry for, and it is an
object of the present invention to provide, an improved
multi-layered plastic container including oxygen scavenging
materials suitable for holding products such as carbonated
beverages or other food products, and having a long shelf life.
[0008] It is a further objective of the present invention to
provide a multi-layered plastic container as aforesaid which may
include desired levels of recycled material.
[0009] It is a still further object of the present invention to
provide a multi-layered plastic container as aforesaid which may be
readily and conveniently prepared at a moderate cost.
[0010] Further objects and advantages of the present invention will
appear hereinbelow.
SUMMARY OF THE INVENTION
[0011] In accordance with the present invention, the foregoing
objects and advantages are readily obtained.
[0012] It is desirable for multi-layered plastic containers to
effectively utilize an oxygen-scavenging material. However, these
materials may not be approved to come into contact with food or
beverage if the container is used to hold these items. In a
multi-layered container the innermost plastic layer would be a
plastic material that is approved for contact with the food or
beverage contents of the container.
[0013] Moreover, after a container is manufactured, it often is not
filled with food or beverage immediately. Naturally, one desires
the oxygen scavenger material to begin working only after the
container is filled. Disadvantageously, an oxygen scavenger may
start to react prior to filling of the container, limiting the
storage life of empty containers in inventory (not filled).
[0014] In accordance with the present invention, a three or more
layered plastic container is provided, wherein
[0015] an innermost first layer is a plastic material, preferably
approved for contact with food or beverage products,
[0016] an intermediate second layer is a plastic material adjacent
the first layer containing an oxygen scavenger material; and
[0017] an outermost third layer is a plastic material, desirably
containing recycled plastic,
[0018] wherein the thickness of the innermost layer is in the range
of 0.1 to 3 mils and is controlled based on the desired shelf life
of the container in the unfilled condition, i.e., the thicker the
innermost layer in this range the greater the protection afforded
the oxygen scavenger material.
[0019] Thus, for example, it has been found that a three layered
plastic container with an innermost layer of polyethylene
terephthalate (PET) that is 0.5 mils thick, and with an
intermediate plastic layer containing an oxygen scavenging
material, can be stored in a warehouse in the unfilled condition
for at least six (6) weeks without the oxygen scavenging material
beginning to react with oxygen. When the container is thereafter
filled with product, as for example, a beverage, the oxygen
scavenging material will be fully effective to protect the product.
Naturally, the innermost layer may be thicker if longer protection
times are desired in the unfilled condition, and thinner if shorter
protection times are desired.
[0020] The process of the present invention comprises:
[0021] forming a plastic container with three or more layers of
plastic, with
[0022] the innermost first layer being a plastic layer preferably
approved for contact with food or beverage products,
[0023] the intermediate second layer is a plastic layer adjacent
the first layer containing at least one oxygen scavenger material,
and
[0024] the outermost third layer is a plastic layer, preferably
containing recycled plastic,
[0025] including the step of controlling the thickness of the
innermost layer in the range of 0.1 to 3 mils based on the desired
shelf life of the container in the unfilled condition.
[0026] Further features of the present invention will appear
hereinbelow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention will be more readily understandable
from the following illustrative drawings, wherein:
[0028] FIG. 1 is an elevational view of a preform for forming a
container in accordance with the present invention;
[0029] FIGS. 1A, 1B and 1C are enlarged cross-sectional views of
various areas of the preform of FIG. 1;
[0030] FIG. 2 is an elevational view of a container of the present
invention; and
[0031] FIGS. 2A, 2B and 2C are enlarged cross-sectional views of
various areas of the container of FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0032] The molded innermost plastic layer is comprised of a
thermoplastic material. The following resins are representative of
resins that may be used as plastic materials for the innermost
layer: polyethylene, polypropylene, polystyrene, cycloolefin
copolymer, polyethylene terephthalate, polyethylene naphthalate,
ethylene-(vinyl alcohol) copolymer, poly-4-methylpentene-1,
poly(methyl methacrylate), acrylonitrile, polyvinyl chloride,
polyvinylidene chloride, styrene-acrylonitrile,
acrylonitrile-butadiene-styrene, polyamide, polyacetal,
polycarbonate, polybutylene terephthalate, ionomer, polysulfone,
polytetra-fluoroethylene, and the like. When food product contents
are involved, the innermost layer should be formed from resins
approved for contact with food products, as virgin polyethylene
terephthalate (PET), polyethylene naphthalate (PEN), and/or blends
of polyethylene terephthalate or polyethylene naphthalate. However,
other thermoplastic resins approved for contact with food products
may also be used.
[0033] The molded outermost layer may be any desired plastic
material, such as those set out hereinabove.
[0034] Desirably, the molded outermost layer includes recycled
plastic material, including the plastics set forth above, but is
preferably formed from recycled polyethylene terephthalate.
[0035] However, the invention is not limited to a particular type
of recycled plastic and other recycled plastic materials may be
used. Moreover, any desired amount of recycled plastic material may
be used in the outermost layer, for example, at least five (5)
percent, at least forty (40) percent, or at least ninety (90)
percent. Further, the outermost layer desirably comprises at least
40% by weight of the total weight of the container, but can
comprise at least 85% by weight of the total weight of the
container. The outermost layer generally has a wall thickness,
taken along its vertical length, that is in the range of 3 to 23
mils (0.1524 mm to 0.5842 mm). Moreover, the thicknesses of each
layer can be separately and independently varied along their
vertical length, as desired.
[0036] The intermediate layer is a plastic layer that contains an
oxygen scavenging material. Oxygen scavenging materials are well
known and include materials marketed for such a purpose by several
large oil companies and resin manufacturers. A specific example of
such a material is marketed under the trade name AMOSORB and is
commercially available from the Amoco Corporation. Polyolefin
oligomer segments are prepared for copolycondensation by first
functionalizing the polyolefin oligomer segments with end groups
capable of entering into polycondensation reactions The polyolefin
oligomers are, in effect, addition polymers. Functionalization of
the polyolefin oligomers with end groups affords a convenient
method for incorporation of addition polymer segments into a
copolycondensate. A preferred polyolefin oligomer as an oxygen
scavenger in the present invention is polybutadiene because it has
good oxygen scavenging capacity and reacts quickly with oxygen
especially in the presence of a transition metal catalyst, such as
cobalt, and in the presence of benzophenone, or both cobalt and
benzophenone. Desirably, the intermediate layer can be made of or
include a barrier material. The barrier material or layer is
desirably an oxygen barrier and is preferably formed from PEN,
saran and ethylene vinyl alcohol copolymers (EVOH) or acrylonitrile
copolymers, such as Barex. The term saran is used in its normal
commercial sense to contemplate polymers made for example by
polymerizing vinylidene chloride and vinyl chloride or methyl
acrylate. Additional monomers may be included as is well known.
Vinylidene chloride polymers are the most commonly used, but other
oxygen barrier materials are will known.
[0037] Naturally, other layers may be provided as desired.
[0038] The container of the present invention may be formed by any
of several known processing techniques which permit the manufacture
of a multi-layered blow molded plastic container having a plastic
molded inner layer and a relatively thick molded plastic outer
layer which may include recycled plastic, and an intermediate
plastic layer, all as aforesaid. In a preferred embodiment, the
multi-layered container is formed via a blow molding operation
involving a multi-layered preform. Although not a required feature,
the preform may include a neck flange, which is convenient for
handling purposes, and outer threads to secure a closure. In a
preferred embodiment, the preform may be produced by extrusion
molding an inner and intermediate layer and injection molding an
outer layer. Extrusion of the preform allows the manufacturer to
produce thinner inner and/or intermediate layers of controlled
thicknesses. Further, an extrusion or co-extrusion process permits
the manufacturer to readily vary the thickness of material being
extruded along the length of the extrudate. The multi-layered
container can then be blow molded using conventional blow molding
operations.
[0039] Referring now to the drawings in detail, there is shown in
FIG. 1 an elevational view of a preform, in accordance with the
present invention, designated generally as 10. Preform 10
preferably includes a threaded and flanged upper portion 12, an
angled intermediate portion 14, a vertical intermediate portion 16
and a base portion 18. In the configuration shown in FIG. 1,
preform 10 is adapted to be blow molded into a container in
accordance with the present invention.
[0040] Referring now to FIGS. 1A, 1B & 1C, which show enlarged
cross-sectional views of areas 1A, 1B and 1C, respectively of FIG.
1, preform 10 is preferably formed from three layers of material.
These clearly show encircling innermost first layer 20, encircling
second intermediate layer 22, and the third outermost layer of the
preform, encircling outer layer 24. As can be seen from FIGS.
1A-1C, the thicknesses of the layers may if desired vary in
accordance with specific portions of preform 10. Outer layer 24
desirably has increased thickness at threaded and flanged upper
portion 12. Innermost layer 20 also desirably may vary in thickness
depending upon the portion of the bottle, i.e., threaded and
flanged upper portion 12, angled and vertical intermediate portions
14 and 16, and base portion 18.
[0041] Innermost layer 20 and intermediate layer 22 are preferably
coextruded via an extrusion process, and outer layer 24 is
preferably formed onto the extruded layers via an injection molding
process, which allows the formation of the threaded upper portion
12. As a result of the extrusion process, innermost layer 20 can be
readily controllably adjusted in thickness based upon the functions
to be performed by the various portions and especially to provide a
desired degree of protection to the oxygen scavenger material in
the intermediate layer.
[0042] The intermediate layer 22 is preferably maintained at a
constant thickness, but this also can be varied in thickness if
desired.
[0043] Variations in thickness of the inner layer are also
desirable for reasons which include aesthetics, efficient material
use and reduced costs, and variable strength requirements.
Efficient material use is evident in innermost layer 20 at upper
portion 12, where innermost layer 20 is thinnest. Strength
considerations are evident in base portion 18, where additional
support is required and as a result, innermost layer 20 may be
thickest.
[0044] With reference now to FIG. 2, a container 58 is shown which
is formed from preform 10 of FIG. 1 via a blow molding operation.
Similar to the preform, container 58 desirably includes a threaded
upper portion 60, an angled intermediate portion 62, a
substantially vertical intermediate portion 64 and a base portion
66, which is shown in the embodiment of FIG. 2 as a self-supporting
base. Naturally, other base configurations may be used, as a footed
base for example. As shown in FIGS. 2A-2C, container 58 also has
three layers of material, each of which may have differing
properties and relative thickness relationships.
[0045] Referring to FIGS. 2A-2C, which represent enlarged
cross-sectional views of areas 2A, 2B and 2C, respectively, of FIG.
2, container 58 includes innermost layer 68, central layer 70 and
outer layer 72. Because innermost layer 68 is not subject to
blowing at the neck region in forming the container shape, the
thickness ratios between the various portions of the container may
differ from those of preform 10. However, the thicknesses of the
layers of the container may if desired vary in accordance with
specific portions of the container in a manner after the thickness
variations of the preform.
[0046] Self-supporting base portion 66 is preferably comprised of a
circumferential encircling member 74, particularly a ring defining
an annulus and an indented center positioned wall 75, whose
function is to sturdily support container 58 on a flat surface.
Encircling member 74 forms the lower circumference of the container
at the lower end 76 thereof. Indented wall 75 joins the inside
portions of encircling member 74 and is located in the center of
encircling member 74. Encircling member 74 starts at the bottom 77
of container 58 and extends upwardly forming lower end 76 and is
continuous with the inner and outer diameters of the container wall
defined by layers 68, 70 and 72 of container 58. Due to the
increased thickness of innermost layer 68 at the self-supporting
base 66, base 66 including encircling member 74 is substantially
harder and less flexible than intermediate portions 62 and 64
providing increased support.
[0047] The shape and parts of container 58, shown in FIG. 2 are by
way of example only and accordingly, a plurality of shapes with
varying parts are contemplated, all of which have a layered
structure similar to as discussed above. For example, the container
may contain greater than three layers if desired and the shape
shown in FIG. 2 is exemplificative only.
[0048] It is to be understood that the invention is not limited to
the illustrations described and shown herein, which are deemed to
be merely illustrative of the best modes of carrying out the
invention, and which are susceptible of modification of form, size,
arrangement of parts and details of operation. The invention rather
is intended to encompass all such modifications which are within
its spirit and scope.
* * * * *