Note: Descriptions are shown in the official language in which they were submitted.
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HIGH BARRIER PLASTIC CONTAIN~R
BACKGROUND OF THE INVENTION
This invention relates to improvements in a
barrier container of the type comprising a gas imperme-
able container body having a side wall that defines an
open end, a closure member, and a gas impermeable
barrier layer bonded to the closure member, wherein the
closure member defines a flange sized to receive the
open end of the container, and wherein the closure
member is spin welded to the open end of the container
body with the open end of the container body received
within the flange.
MacLaughlin U.S. Patent 4,892,227, assigned -~
to the assignee of the present invention, discloses a
high barrier plastic container of the type described
a~ove. In the disclosed container the barrier layer 28
of the closure member 24 is formed of a metal foil such
as aluminum, and this barrier layer 28 includes a
portion that extends in contact with the inner wall of
the container 20. In so doing, the container of the
MacLau~hlin patent differs from the prior art practice
as shown for example in Del Bon U.S. Patent 4,333,585,
Jeppsson U.S. Patent 4,212,409 and U.K. Patent Appli-
cation GB 2120200. In all of these cases the ~arrier
layer is shown as wrapping around the open end of the
container ~ody, such that the barrier layer of the
closure contacts ~oth the inner and outer side walls of
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the container body. One advantage of this prior art
approach is that it maximizes contact between the
barrier layer of the closure and the barrier layer of
the container body, and thereby promotes a high barrier
closure.
However, the prior art approach demonstrated
in the Del Bon, Jeppsson and British patent applica-
tions are not believed to be optimally suited for a
spin welded closure of the type described in the
MacLaughlin patent. It is believed that an optimal
spin weld bond is obtained by direct bonding between
the container body and the closure. If the barrier
layer were to intrude into the region of the bond
between the closure and the container body, it is
believed that such an intrusion would not enhance the
quality or the integrity of the spin weld bond.
Thus, it is an object of this invention to
provide a spin weld container of the type described
above having improved barrier characteristics as
compared with the container of the MacLaughlin patent,
without degrading the spin weld bond between the
closure and the container body.
As mentioned above, the MacLaughlin patent
discloses the use of an aluminum foil 28 as a barrier
layer on the closure. This approach can be used to
form an effective closure and an effective barrier
layer. However, an aluminum foil barrier layer is not
without disadvantages in certain applications.
~ irst, since the aluminum foil disclosed in
the MacLaughlin patent is bonded to the closure member
the MacLaughlin patent does not disclose an all plastic
container. The metal foil remaining in the portion of
the closure spin that is welded to the container body
can result in microwave problems when the opened con-
tainer is heated in a microwave oven. Second, ~ecause
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the metal foil is bonded to the plastic of the closure,
certain recycling disadvantages are inherent. Third,
it has been discovered that in the event the dimensions
of the closure and the container body are not con-
trolled properly, a metallic barrier layer can result
in metallic impurities being in~roduced into the
contents of the container. For example, it is well
known that plastic components change in dimension as
they age. Such dimensional changes can result in a
situation where the container body is smaller than
intended and where the inside wall of the container
body comes into high speed contact with the barrier
layer of the closure during the spin welding process.
When this happens the barrier layer can be disrupted
into a fine dust, which may find its way into food
contained within the container. This result is of
course unacceptable.
It is another object of this invention to
provide an improved high barrier plastic container
which aYoids the use of a metallic barrier layer in
order to eliminate the above mentioned problems.
SUMMARY OF THE INVENTION
This invention relates to improvements to the
barrier container described initially above having a
gas impermeable container body and a closure member
having a gas impermeable barrier layer bonded thereto,
wherein the closure member is spin welded to the open
end of the container body.
According to a first aspect of this in-
vention, a radially outer portion of the barrier layer
is disposed across the side wall at the open end of the
container body. The side wall of the container body
~efines an outer surface adjacent the open end, and the
barrier layer is positioned to avoid any substantial
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contact with the outer surface, thereby enhancing
direct spin welding bonding between the container body
and the closure member, while simultaneously enhancing
the barrier characteristics of the container.
According to a second aspect of this in-
vention, a barrier container of the type described
above includes a plurality of a co-extensive layers
included in the barrier layer. This plurality of
layers comprises at least one non-metallic high barrier
layer and a pair of non-metallic flanking layers, each
on a respective side of the non-metallic high barrier
layer. The barrier layer, the container and the
closure member are all devoid of any metallic layers.
In this way, the disadvantages described above related
to metallic layers are all avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a top view of a closure member of
a container that incorporates a presently preferred
embodiment of this invention.
Figure 2 is a cross-sectional view taken
along line 2-2 of Figure 1.
Figure 3 is an enlarged view of region 3 of
Figure 2.
Figure 4 is an enlarged view of region 4 of
Figure 3.
Figure 5 is an enlarged view of region 5 of
Figure 3.
DETAILED DESCRIPTION OF THE
PRESENTLY PREFERRED EM80DIMENTS
Turning now to the drawings, Figures 1 and 2
show general views ~f a container 10 which includes a
container body 12 and closure member 20. Only the
upper portion of the container body 12 is illustrated
in Figure 2, but in general the container body 12 is
barrel shaped and defines an open end 14 and a closed
end (not shown). The open end 14 is defined by a side
wall 16 having an outer surface 18. The outer surface
is preferably circularly cylindrical in shape.
The closure member 20 defines a perimeter
flange 22 that is integrally molded with a central
panel 23. The flange 22 defines a circular groove 24
that terminates at a root 26.
The aspects of the container 10 described
above are quite similar to those described in
MacLaughlin ~.S. Patent 4,892,227, the disclosure of
which is hereby incorporated by reference.
Figures 3, 4 and 5 are enlarged views that
provide more detailed illustrations of selected aspects
of the closure member 20. As best shown in Figure 3,
the closure member 20 includes a barrier layer 3~
having a circular inner portion 32 which is integral
with an intermediate annular portion 34. The annular
portion 34 extends generally at right angles to the
inner portion 32. The barrier layer 30 also includes a
radially outer annular portion 36 which is generally
disposed parallel to the inner portion 32.
As shown in Figure 3, the radially outer
annular portion 36 extends across the root 26 of the
groove 24, where it is disposed to come into contact
with the open end 14 of the body 12. If desired, the
radially outer annular portion 36 can be curved
slightly to follow the shape of the root 26 of the
groove 24. However, the radially outer annular portion
36 preferably does not come into any substantial
contact with the outer surface 18 of the side wall 16
of the container body 12.
The illustrated geometry provides two
important advantages. First, the radially outer
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annular portion 36 crosses the root 26 of the groove 24
and thereby comes into contact with the open end 14.
This provides improved contact between the barrier
layer 30 and the barrier layer 19 of the container body
12. Second, because the barrier layer 30 does not come
into any substantial contact with the outer surface 18,
the barrier layer 30 does not reduce the area of direct
spin welding between the flange 22 and the container
body 12. Thus, the high barrier characteristics of the
container 10 are enhanced without detracting from the
integrity of the spin weld bond 50.
Figure 4 shows an enlarged view of the
barrier layer 30, and it can be seen that the barrier
layer 30 is formed of five layers. The central layer
is a high barrier layer 38 which is substantially gas
impermeable. The high barrier layer 38 is covered on
each side by a respective flanking layer 40, and the
flanking layers 40 are secured in place adjacent the
high barrier layer 38 by respective adhesive layers 42.
Preferably, the layers 38, 40, 42 are co-extruded as
co-extensive layers in a sheet. This sheet is then
thermally formed to the shape shown in Figure 3 and
trimmed to size. Then the preshaped barrier layer is
placed within a injection molding machine, and the
resin material used to form the closure member 20
including the flange 22 is shot into the injection
molding machine from the top surface only. The heat of
the injection melt fuses the melt to the barrier layer
30.
Figure 5 shows an enlarged view of a weakened
line 44 which is provided to allow easy opening of the
closure member 20.
The barrier layer 30 completely eliminates
any metallic layer in the barrier layer 30. As
illustrated, neither the container body 12 nor the
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closure member 20 includes any metallic layer. In this
way, all metallic layers are avoided, and the advant-
ages discussed above are obtained.
In particular, in the event the container 10
is smaller than desired and the container 10 comes into
high speed contact with the barrier layer 30 during the
spin weld process, no metallic elements will be
deposited on the contents of the container 10.
The following details of construction are
provided in order better to define the presently
preferred embodiments.
A wide variety of resins can be used to form
the container 10 and the closure member 20. However,
the following resin blend is presently preferred for
the closure member 20:
a) Polypropylene (Rexene PP57S20V) - 94%
b) Linear low density polyethylene
(Novacore GI-5026A) - 2%
c) Color - Ferro CH31029 - 4%
Similarly, a variety of materials can be used
for the barrier layer 30. The following materials are
presently preferred:
a) Central high barrier layer 38 - Saran
(Dow XU.31MA)
b) Flanking layer 40 - Polypropylene
(Himont 6331)
c) Adhesi~e layer 42 - Exxon Esorene 5610
The presently preferred thickness of the layers 38~ 40,
42 are 0.003, 0.002, and 0.0015 inches, respectively.
~he presently preferred width and thickness of the
reduced thickness line 44 are 0.005 and 0.003 inches,
respectively.
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Other materials can be substituted. For
example, the adhesive identified as Admer QF551 has
also been found suitable for the adhesive layer 42 and
EVOH (Evalca LCL lOlA) has been found suitable for the
central high barrier layer 38.
of course, it should be understood that a
wide range of changes and modifications can be made to
the preferred embodiments described above. It is
therefore intended that the foregoing detailed descrip-
tion be regarded as illustrative rather than limiting,
and that it be understood that it is the following
claims, including all equivalents, which are intended
to define the scope of this invention.
