U.S. patent application number 11/756186 was filed with the patent office on 2009-01-08 for finish and closure for plastic pasteurizable container.
This patent application is currently assigned to Graham Packaging Company, L.P.. Invention is credited to Amit S. Agrawal, Wayne N. Collette, David P. Piccioli.
Application Number | 20090008360 11/756186 |
Document ID | / |
Family ID | 39590696 |
Filed Date | 2009-01-08 |
United States Patent
Application |
20090008360 |
Kind Code |
A1 |
Piccioli; David P. ; et
al. |
January 8, 2009 |
FINISH AND CLOSURE FOR PLASTIC PASTEURIZABLE CONTAINER
Abstract
Plastic containers subjected to pasteurization processes with a
closure having an annular finish support ring that supports an
inner surface of the neck finish of the container from inward
deformation during pasteurization. The finish support ring can be
integral with the closure or can extend from a closure liner. Also
disclosed are closures for products that require pasteurization, as
well as modified finish threads to provide a surface contact
between the finish and closure threads.
Inventors: |
Piccioli; David P.; (Auburn,
NH) ; Agrawal; Amit S.; (Merrimack, NH) ;
Collette; Wayne N.; (Merrimack, NH) |
Correspondence
Address: |
RISSMAN JOBSE HENDRICKS & OLIVERIO, LLP
100 Cambridge Street, Suite 2101
BOSTON
MA
02114
US
|
Assignee: |
Graham Packaging Company,
L.P.
York
PA
|
Family ID: |
39590696 |
Appl. No.: |
11/756186 |
Filed: |
May 31, 2007 |
Current U.S.
Class: |
215/381 ;
215/329 |
Current CPC
Class: |
B29B 2911/14733
20130101; B29B 2911/148 20130101; B29K 2023/086 20130101; B60R
2019/1886 20130101; B29B 2911/14066 20130101; B60K 13/04 20130101;
B29B 2911/14466 20130101; B29L 2031/7158 20130101; B29B 2911/14446
20130101; B60R 19/50 20130101; B29K 2027/08 20130101; B60Q 1/2626
20130101; B29K 2077/00 20130101; B60K 13/02 20130101; B29B
2911/14093 20130101; B29K 2023/083 20130101; B60R 19/18 20130101;
B29K 2067/00 20130101; B29B 2911/1408 20130101; B60Q 1/2653
20130101; B65D 1/0246 20130101; B65D 41/0414 20130101; Y10T
29/49826 20150115; B29B 2911/1404 20130101; B29B 11/14 20130101;
B29B 2911/14033 20130101; B65D 41/0435 20130101; B29B 2911/14106
20130101; B29B 2911/1402 20130101; B29B 2911/14113 20130101; B29B
2911/14053 20130101; B29B 2911/14026 20130101 |
Class at
Publication: |
215/381 ;
215/329 |
International
Class: |
B65D 90/02 20060101
B65D090/02; B65D 41/04 20060101 B65D041/04 |
Claims
1. A plastic closure for supporting an amorphous neck finish of a
pasteurizable plastic container against deformation, comprising: a
top wall; a depending annular skirt extending from the top wall;
and a rigid finish support ring extending from the top wall, the
finish support ring having an outer diameter sized to support an
inner diameter of the amorphous container neck finish against
inward deformation during pasteurization.
2. The plastic closure of claim 1, wherein an inner wall of the
skirt includes a thread for engaging a complementary thread on the
container neck finish.
3. The plastic closure of claim 1, wherein the plastic closure
comprises a polyolefin material and the neck finish comprises one
or more of a polyester, polyamide, and polyolefin material.
4. The plastic closure of claim 1, further comprising a liner
covering at least a portion of an underside of the top wall.
5. The plastic closure of claim 4, wherein the liner comprises a
gas barrier material.
6. The plastic closure of claim 4, wherein the liner covers the
area of the top wall defined by the inner diameter of the finish
support ring.
7. The plastic closure of claim 4, wherein the liner covers the
area of the top wall between the outer diameter of the finish
support ring and the inner diameter of the skirt.
8. A plastic closure for supporting an amorphous neck finish of a
pasteurizable plastic container against deformation, comprising: a
shell comprising a top wall and a depending annular skirt extending
from the top wall; a liner covering at least a portion of the
underside of the top wall; and a rigid finish support ring
extending from the liner, the finish support ring having an outer
diameter sized to support an inner diameter of the amorphous
container neck finish against inward deformation during
pasteurization.
9. The plastic closure of claim 8, wherein the plastic closure
comprises a polyolefin material and the neck finish comprises one
or more of a polyester, polyamide, and polyolefin material.
10. The plastic closure of claim 8, wherein the liner comprises a
polyolefin material and the neck finish comprises one or more of a
polyester, polyamide, and polyolefin material.
11. The plastic closure of claim 9, wherein the plastic closure and
liner are made from the same material.
12. A pasteurizable package comprising: a pasteurizable plastic
container having an amorphous neck finish; and a plastic closure
comprising a depending annular skirt extending from a top wall and
a rigid finish support ring extending from the top wall, the finish
support ring having an outer diameter sized to support an inner
diameter of the amorphous container neck finish against inward
deformation during pasteurization.
13. The package of claim 12, wherein an inner wall of the closure
skirt includes a thread for engaging a complementary thread on the
container neck finish.
14. The package of claim 12, wherein the container thread is vented
and the closure thread is nonvented.
15. The package of claim 12, wherein the engagement between the
closure thread and the container thread is by surface contact.
16. The package of claim 15, wherein the surface contact is between
a bottom surface of the container thread and a top surface of the
closure thread.
17. The package of claim 12, wherein the closure thread is
nonvented.
18. The package of claim 12, wherein the closure comprises a
polyolefin material and the neck finish comprises one or more of a
polyester, polyamide, and polyolefin material
19. The package of claim 18, wherein the closure comprises a
polyolefin material and the neck finish comprises a polyethylene
terephthalate material.
20. A pasteurizable package comprising: a plastic pasteurizable
container comprising an amorphous neck finish having a vented
thread; and a plastic closure comprising a top wall and a depending
annular skirt, an inner wall of the skirt having a nonvented thread
that engages the vented thread of the neck finish, wherein a
surface of the nonvented closure thread contacts a surface of the
vented container thread to provide surface contact between the
closure thread and the container thread and to support the
container thread against deformation during pasteurization.
21. The package of claim 20, wherein the surface of the container
thread is positioned at the underside of the container thread and
contacts an upper surface of the closure thread.
22. The package of claim 20, wherein the surface of the vented
container thread and the closure thread are both substantially
flat.
23. The package of claim 22, wherein the surface of the vented
container thread and the closure thread have an angle with the
horizontal of 10.degree. or less.
24. The package of claim 22, wherein the surface of the vented
container thread and the closure thread have an angle with the
horizontal of 5.degree. or less.
25. The package of claim 22, wherein the surface of the vented
container thread and the closure thread have an angle with the
horizontal of 0.degree..
26. The package of claim 20, wherein the surface of the vented
container thread and the closure thread are both curved.
27. The package of claim 20, wherein the container comprises a
polyethylene terephthalate material.
28. The package of claim 27, wherein the closure comprises a
polyolefin material.
29. A pasteurizable package comprising: a plastic pasteurizable
container comprising an amorphous neck finish having a thread; and
a plastic closure comprising a top wall and a depending annular
skirt, an inner wall of the skirt having a thread that engages the
thread of the neck finish, wherein the container thread contacts
the closure thread at a distance of at least 50% of the radial
depth of the thread, as measured from the tip of the thread to a
wall of the neck finish, to support the container thread against
deformation during pasteurization.
30. The package of claim 29, wherein the container thread contacts
the closure thread at a distance of at least 65% of the radial
depth of the thread, as measured from the tip of the thread to a
wall of the neck finish.
31. The package of claim 29, wherein the container thread contacts
the closure thread at a distance of at least 75% of the radial
depth of the thread, as measured from the tip of the thread to a
wall of the neck finish.
32. The package of claim 29, wherein the container thread contacts
the closure thread at a distance of at least 85% of the radial
depth of the thread, as measured from the tip of the thread to a
wall of the neck finish.
33. The package of claim 29, wherein the container thread contacts
the closure thread via a surface at the underside of the container
thread.
34. The package of claim 29, wherein the surface at the underside
is substantially flat.
35. The package of claim 34, wherein the surface at the underside
has an angle with the horizontal of 10.degree. or less.
36. The package of claim 34, wherein the surface at the underside
has an angle with the horizontal of 5.degree. or less.
37. The package of claim 34, wherein the surface at the underside
has an angle with the horizontal of 0.degree..
38. The package of claim 29, wherein the contact between the
container thread and the closure thread is a point contact.
39. The package of claim 29, wherein the contact between the
container thread and the closure thread is a surface contact,
wherein one extremity of the surface contact occurs at a distance
of at least 50% of the radial depth of the thread, as measured from
the tip of the thread to a wall of the neck finish.
40. The package of claim 29, wherein the contact between the
container thread and the closure thread is a surface contact,
wherein one extremity of the surface contact occurs at a distance
of at least 65% of the radial depth of the thread, as measured from
the tip of the thread to a wall of the neck finish.
41. The package of claim 29, wherein the contact between the
container thread and the closure thread is a surface contact,
wherein one extremity of the surface contact occurs at a distance
of at least 75% of the radial depth of the thread, as measured from
the tip of the thread to a wall of the neck finish.
42. The package of claim 29, wherein the contact between the
container thread and the closure thread is a surface contact,
wherein one extremity of the surface contact occurs at a distance
of at least 85% of the radial depth of the thread, as measured from
the tip of the thread to a wall of the neck finish.
43. The package of claim 39, wherein the surface contact occurs
between a surface at the underside of the container thread and an
upper surface of the closure thread.
44. The package of claim 43, wherein the surface at the underside
of the container thread and the upper surface of the closure thread
are substantially flat.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to plastic container finish
and closure systems that are subjected to pasteurization
processes.
BACKGROUND OF THE INVENTION
[0002] Many products require pasteurization to reduce the number of
microorganisms that may be present in the product (e.g., food or
beverage) during packaging and that can degrade the product. One
known pasteurization process is performed after the containers are
filled with product and sealed, and involves gradually elevating
the temperature of the filled and sealed containers to a desired
temperature (e.g., 140.degree. F. for beer), where it is held for a
period of time. The container and its contents are then cooled to
ambient temperatures where the containers can be labeled, packaged,
and stored. Products that are typically pasteurized include fruit
juices, milk, and beer.
[0003] Although products such as beer have historically been
pasteurized in glass bottles, it would be desirable to use plastic
containers, e.g., containers comprising polyethylene terephthalate
(PET) for products requiring pasteurization. Because a container
experiences a range of temperatures during pasteurization, these
conditions can cause a plastic container to undergo permanent,
uncontrolled deformation. Accordingly, there remains a need to
provide plastic containers that can withstand pasteurization with a
minimum of deformation.
[0004] It is known to crystallize the neck finish of a plastic
container for purposes of increasing its thermal stability. Thus,
it is known to provide a thermally crystallized PET container
finish to prevent distortion of the neck finish during
pasteurization. However, there is a significant increase in cost
involved in crystallizing the finish in order to prevent
distortion. It would thus be desirable to provide a pasteurizable
package which does not require crystallization of the container
neck finish.
SUMMARY OF THE INVENTION
[0005] In accordance with various embodiments of the invention
disclosed herein, there is provided a plastic closure for
supporting an amorphous neck finish of a pasteurizable plastic
container against deformation. This closure can be used to minimize
the finish distortions which normally occur at the high
temperatures and pressures involved in the pasteurization process,
and as a result, prevent any significant loss of pressure and/or
product leakage.
[0006] In further embodiments, the closure can be provided with a
liner to enhance seal integrity. Still further, the one or more
threads on the container neck finish can be modified to increase
the surface contact between the container thread and closure
thread, for example, by providing complementary planar thread
profiles on the container and closure threads, which provide
surface contact and support features. Alternatively, or in
addition, one can modify the angle and/or depth of a thread for a
greater resistance to deformation. Still further, the container
thread may be thickened to further prevent deformation. For
example, an increased depth of the container thread, or contact at
a region that takes advantage of the greater thread thickness
closer to the neck finish wall can be used to withstand the
conditions of pasteurization without loss of seal integrity.
[0007] In a further embodiment, a nonvented closure thread is
provided so as to prevent nonuniform deformation of the container
thread during pasteurization.
[0008] In accordance with one embodiment of the invention,
disclosed herein is a plastic closure for supporting an amorphous
neck finish of a pasteurizable plastic container against
deformation, comprising: [0009] a top wall; [0010] a depending
annular skirt extending from the top wall; and [0011] a rigid
finish support ring extending from the top wall, the finish support
ring having an outer diameter sized to support an inner diameter of
the amorphous container neck finish against inward deformation
during pasteurization.
[0012] Another embodiment provides a plastic closure for supporting
an amorphous neck finish of a pasteurizable plastic container
against deformation, comprising: [0013] a shell comprising a top
wall and a depending annular skirt extending from the top wall;
[0014] a liner covering at least a portion of the underside of the
top wall; and [0015] a rigid finish support ring extending from the
liner, the finish support ring having an outer diameter sized to
support an inner diameter of the amorphous container neck finish
against inward deformation during pasteurization.
[0016] Another embodiment provides a pasteurizable package
comprising: [0017] a pasteurizable plastic container having an
amorphous neck finish; and [0018] a plastic closure comprising a
depending annular skirt extending from a top wall and a rigid
finish support ring extending from the top wall, the finish support
ring having an outer diameter sized to support an inner diameter of
the neck finish against inward deformation during
pasteurization.
[0019] Another embodiment provides a pasteurizable package
comprising: [0020] a plastic pasteurizable container comprising an
amorphous neck finish having a vented thread; and [0021] a plastic
closure comprising a top wall and a depending annular skirt, an
inner wall of the skirt having a nonvented thread that engages the
vented thread of the neck finish, [0022] wherein the nonvented
closure thread has a planar surface that contacts a planar surface
of the vented container thread to provide substantially planar
surface contact between the closure thread and the container thread
and to support the container thread against deformation during
pasteurization.
[0023] Another embodiment provides a pasteurizable package
comprising: [0024] a plastic pasteurizable container comprising an
amorphous neck finish having a thread; and [0025] a plastic closure
comprising a top wall and a depending annular skirt, an inner wall
of the skirt having a thread that engages the thread of the neck
finish, [0026] wherein the container thread contacts the closure
thread at a distance of at least 50% of the radial depth of the
thread, as measured from the tip of the thread to a wall of the
neck finish, to support the container thread against deformation
during pasteurization.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Various embodiments of the invention will be understood from
the following description, the appended claims and the accompanying
drawings, in which:
[0028] FIG. 1 is a schematic view of a pasteurization tunnel;
[0029] FIG. 2A is a sectional view of a finish capped with a
closure prior to heating;
[0030] FIG. 2B is a sectional view of the capped finish of FIG. 2A
that has been heated to pasteurization temperatures;
[0031] FIG. 2C is a sectional view of the capped finish of FIG. 2B
that has been subsequently cooled;
[0032] FIG. 3 is a sectional view of a container capped with a
closure having a finish support ring;
[0033] FIG. 4 is a sectional view of a container capped with a
closure having a liner with a finish support ring;
[0034] FIG. 5 is a sectional view of a container capped with a
closure having a finish support ring and additional oxygen barrier
and/or oxygen scavenging inner liner;
[0035] FIG. 6 is a sectional view of a container capped with a
closure having a finish support ring and additional oxygen barrier
and/or oxygen scavenging outer liner;
[0036] FIG. 7 shows a container neck finish with deformed
threads;
[0037] FIG. 8A is a detailed sectional view of a bottle thread
having point contact with a closure thread;
[0038] FIG. 8B is a detailed sectional view of bottle and closure
threads having surface contact;
[0039] FIG. 8C is a detailed sectional view of a finish thread
modified to have an additional thickness;
[0040] FIG. 8D is a detailed sectional view of a finish thread
contacting a bottle thread at the midpoint region of the finish
thread;
[0041] FIG. 8E is a detailed sectional view of a finish thread
contacting a bottle thread at a region of the finish thread closer
to the finish wall; and
[0042] FIG. 9 schematically depicts a device for applying a
predetermined amount of force to a neck finish.
DETAILED DESCRIPTION
[0043] Disclosed herein are plastic container packages for products
that require pasteurization.
[0044] The pasteurization process has been mechanized and automated
for mass packaging. A typical pasteurization apparatus is a tunnel
pasteurizer, such as those described in U.S. Pat. Nos. 2,282,187,
4,441,406, and 4,693,902, the disclosures of which are incorporated
herein by reference. FIG. 1 schematically shows a system 1 that
includes apparatus and processes for the manufacture, filling and
pasteurization of a filled plastic container 8 in a pasteurization
tunnel 2. System 1 includes a conveyer belt 3 for conveying the
containers through stations for filling, capping, and
pasteurization processes. A central longitudinal axis A of the
container 8 is shown in FIG. 1 and serves throughout this
specification as a reference point of orientation (e.g., radially
outward from axis A).
[0045] In FIG. 1, container 8 is manufactured in blow mold 6 and
downstream from blow mold 6 (in the direction indicated by the
arrows) container 8 is carried by conveyer belt 3 to zone 10 for
filling with the contents to be pasteurized, to zone 12 for sealing
with a closure 9, and finally to the pasteurization tunnel 2
through tunnel entrance 4. In tunnel 2, various heating and cooling
zones progressively raise and subsequently lower the temperature of
the filled and sealed container. These heating/cooling zones
comprise a series of showers each having a predetermined
temperature. In tunnel 2, container 8 is first wetted by a first
set of showers in zone 14 to gradually increase the temperature of
container 8 and its contents. FIG. 1 schematically shows only one
set of showers in each of zones 14, 16, and 18, although the number
can vary to two or more depending on the desired rate of
temperature change, and/or length of time to maintain the bottle at
a desired temperature. Subsequently, shower(s) in zone 16 maintain
bottle 8 at a pasteurization temperature, e.g., 140.degree. F. for
beer. The container 8 is then conveyed to zone 18 where shower(s)
cool the bottle 8 down to ambient temperature. A precooling liquid
in zone 18 may be at a temperature of 125.degree. F., optionally
followed by successive cooling sprays at for example 75.degree. F.
and 60.degree. F. Bottle 8 emerges from the pasteurization tunnel 2
through exit 5 at a desired temperature with the pasteurized
product ready for labeling and distribution.
[0046] The conveyer belt can have the design of U.S. Pat. No.
2,658,608, the disclosure of which is incorporated herein by
reference. Alternatively, the method of conveyance can involve a
walking beam as described in U.S. Pat. No. 4,441,406, the
disclosure of which is incorporated herein by reference. One of
ordinary skill in the art would readily appreciate that the blow
molding, filling, capping and/or conveying processes do not
necessarily occur in or with the same apparatus as that used for
pasteurization and can be performed with a different apparatus.
[0047] Tunnel 2 of FIG. 1 illustrates one embodiment of a
pasteurization system. However, it will be apparent to those
skilled in the art that different forms of apparatus may be
employed to carry out the pasteurization process, and the various
parameters of the process (e.g., time and temperatures of the
liquid sprayed on the containers) may be varied in accordance with
the nature of the product to be treated and the results desired.
For example, FIG. 1 depicts three heating and cooling zones,
although any number of spray systems can be used as known in the
art, e.g., more zones can be used and each zone can comprise one or
more showers using any number of designs known in the art.
[0048] Due to the range of temperatures experienced by the
container during pasteurization (e.g., from room temperature to
140.degree. F.), plastic containers enclosing products that require
pasteurization can experience deformations in the neck finish. An
example of such neck deformation is illustrated schematically in
FIGS. 2A-2C. FIG. 2A shows a sectional view of a neck finish 30
capped with closure 40 prior to pasteurization. Closure 40
comprises top wall 42 and a depending skirt 44 extending from the
perimeter of wall 42. Threads 46 line the inner diameter of skirt
44, and engage complementary outer threads 36 of neck finish 30.
Closure 40 may optionally have a liner 48 that covers the underside
of top wall 42 to provide an additional seal.
[0049] During the heating phase of pasteurization, the liquid
product and head space gases expand within the sealed container.
For example, when a container is filled with beer, the pressure can
increase from, e.g., 15 psi while cold (if the container is
cold-filled with beer at e.g. 35.degree. F.) to approximately 45
psi at ambient temperature (75.degree. F.), and can peak at
approximately 85 psi at a pasteurization temperature of 140.degree.
F. Other products may experience different pressure changes. At
these higher pressures, the gas expansion can cause top wall 42 of
closure 40 to dome upward in the direction of arrow 31, as shown in
FIG. 2B. This doming applies an inward force at an upper portion of
skirt 44 in the approximate direction of arrows 32, resulting in
movement of the upper end of the bottle neck inward, as indicated
by deformed region 37. After the bottle cools, as shown in FIG. 2C,
the closure 40 relaxes back to its original formation. However, the
upper neck finish at 37 remains in its inward deformed condition,
indicated by the solid lines (dotted lines indicate the original
shape of the neck finish).
[0050] Neck finish deformations, such as that described above, can
affect the integrity of the product (e.g., loss of carbonation
pressure, exposure to oxygen, leakage of product). For example, the
seal between the neck finish and closure can be compromised by the
doming, as the contact between the neck and liner and/or the neck
and closure engagement threads can be reduced due to the deformed
neck.
[0051] Accordingly, one embodiment provides a plastic closure for
engaging a neck finish of a container. The plastic closure is
capable of supporting an inner diameter of the container neck to
substantially prevent permanent inward deformation of the neck
caused by the pasteurization process.
[0052] FIG. 3 shows one embodiment of a closure of the present
invention. A neck finish 30 is capped by a closure 50 having a top
wall 52 and an annular skirt 54 extending from the perimeter of top
wall 52. An inner diameter of skirt 54 has inner threads 56 that
engage complementary outer threads 36 of neck finish 30. A rigid
integral finish support ring 53 also extends from top wall 52,
where the finish support ring 53 has an outer diameter 55 less than
the inner diameter of the annular skirt 54. Specifically, the outer
diameter 55 of finish support ring 53 has a dimension that allows
the finish support ring 53 to engage and thus support an inner
diameter 33 of the container neck finish 30 against inward
deformation, e.g., of the type illustrated in FIGS. 2B and 2C; the
outer diameter 55 is thus substantially equal to (may be slightly
less than) the inner diameter 33 of neck finish 30. In one
embodiment, finish support ring 53 sealingly engages inner diameter
33 of neck finish 30. Moreover, finish support ring 53 has
sufficient rigidity, based on material, and dimensions, e.g., to
support inner diameter 33, and thus the neck finish 30, to
substantially prevent inward deformation. In one embodiment, the
dimensions of the finish support ring are determined based on at
least one of the finish support ring thickness and length, e.g.,
the length the finish support ring extends into finish, where the
length of the finish support ring can be measured from the
underside 58 of top wall 52 of the closure 50 to the bottom end of
the finish support ring 53 (see FIG. 3).
[0053] The bottle can comprise a polyester, such as polyethylene
terephthalate, either as a single layer or multi-layer
incorporating other resins, such as polyamides, polyolefins,
polyvinylidene chloride (PVDC) and ethylene vinyl alcohol (EVOH).
The closure can be made of polyolefins, such as polyethylene (high
or low density), polypropylene, or copolymers thereof. For example,
the closure can be a compression-molded polypropylene cap able to
withstand the pasteurization process without deformation.
[0054] FIG. 3 depicts finish support ring 53 as an integral portion
of closure 50. Alternatively, a solid plug (extending across the
full inner diameter of the neck finish) can be provided in place of
finish support ring 53, the plug having the same outer diameter as
finish support ring 53. Other designs can be envisioned by one of
ordinary skill in the art to support inner diameter 33 of the neck
finish 30.
[0055] FIG. 4 shows another embodiment of a closure of the present
invention where the finish support ring is not integral with the
closure. Closure 70 comprises top wall 72 and depending skirt 74.
Closure 70 has threads 76 around an inner diameter of skirt 74 to
engage complementary threads 36 of neck finish 30. Instead of the
integral finish support ring of FIG. 3, a plastic liner 71 in FIG.
4 covers the underside of top wall 72. A rigid finish support ring
73 extends from liner 71 where the outer diameter 75 of finish
support ring 73 is substantially equal to (may be slightly less
than) the inner diameter 33 of neck finish 30. As with the finish
support ring 53 of FIG. 3, finish support ring 73 of FIG. 4 has
suitable dimensions and rigidity to support inner diameter 33 of
neck finish 30 from inward deformation during pasteurization.
[0056] The liner may cover the entire underside of top wall 72, as
shown in FIG. 4, or alternatively, cover only the portion of wall
72 that contacts rim 35 of neck finish 30. The liner can be made of
the same materials as the closure, e.g. a rigid plastic such as a
polyolefin, or can be made from a material different from that of
the closure.
[0057] Depending on the product, the closure of the invention can
include a liner made from a gas barrier material, e.g., an oxygen
barrier material, including one or both of passive and active
barrier materials. FIG. 5 shows the closure of FIG. 3 containing in
addition a liner 51 covering the underside of the top wall 52 over
the area defined by the inner wall of finish support ring 53.
Exemplary active barrier materials include oxygen scavenging
materials, such as those disclosed in U.S. Pat. Pub. No.
2004/0043172. Exemplary passive barrier materials include those
chosen from elastomers, plastisol, polyolefins, ethylene vinyl
acetate (EVA), ethylene vinyl alcohol (EVOH), polyvinyl alcohol
(PVOH), polyvinyldene chloride (PVDC), polyethylene naphthalate
(PEN), polyacrylonitrile (PAN), styrene acrylonitrile (SAN), liquid
crystal polymer (LCP).
[0058] Alternatively, or in addition to liner 51, FIG. 6 shows the
closure 50 of FIG. 3 further comprising an outer annular liner 57
comprising an active oxygen scavenging material or a passive oxygen
barrier material, such as those disclosed herein. Annular liner 57
extends outwardly from the outer diameter 55 of finish support ring
53 to the inner diameter of skirt 54 to provide a seal against rim
35 of neck finish. Optionally, annular liner 57 can extend over
only a portion of closure 50 that would contact rim 35 of neck
finish 30.
[0059] Liners 51 and/or 57 of FIGS. 5 and 6, respectively, can also
be incorporated in the closure 70 of FIG. 4. Liners 51 and/or 57
can cover the underside of liner 71 in the same manner that it
would cover the underside of top wail 52 of closure 50 (FIG.
3).
[0060] In addition to affecting the shape of neck finish 30, the
deformations from pasteurization can also affect the integrity of
the finish threads 36. For example, where the threads of the
closure are vented, e.g., segmented (not continuous) in a manner to
allow a pathway to relieve excess pressure, the doming of the
closure and accompanying inward deformation of the neck finish
during heating, as shown in FIG. 2B, can cause the neck finish
threads and segmented closure threads to push against each other.
FIG. 7 shows a perspective view of a neck finish 80 having
continuous finish threads 82 after the neck finish was subjected to
pasteurization utilizing a closure with segmented closure threads.
The resulting finish threads 82 have intermittent bends or
deformations 84 from pressure contact with the segmented closure
threads. The ratchet-type deformation of the neck finish threads
makes removal of the closure more difficult and may otherwise be
undesirable (e.g., produce a clicking sound) from a customer (user)
perspective. Also, as the threads are displaced upwards, the seal
in contact with the bottle becomes compromised.
[0061] Accordingly, one embodiment provides a closure having
nonvented (continuous, non-segmented) threads that engage
complementary threads of the neck finish. If finish thread
deformation occurs due to contact between the closure and neck
finish threads, the continuous closure threads will cause a more
even deformation of the neck finish threads and thus substantially
eliminate the formation of segmented bends or ratchet-type
deformations of the neck finish threads.
[0062] In another embodiment, the threads of the neck finish and
closure are vented. Vented finish threads may be desirable for use
with pressurized products such as carbonated beverages (e.g.,
water, soda, and beer).
[0063] Another embodiment of a bottle finish that can withstand
pasteurization conditions includes neck finish threads that engage
the closure threads via surface contact. In contrast, FIG. 8A shows
a sectional view of a point-type engagement 96 between a lower
surface of thread 91 of a container neck finish 90, and an upper
surface of a thread 101 of a closure 100. Container thread 91 is
vented and has a mostly curved sectional profile, except for two
converging surfaces 92 (upper) and 93 (lower), which are
substantially planar (as indicated by the dotted lines), the
cross-section of which are shown as straight line portions. The
lower converging surface 93 of container thread 91 is sloped
generally upward when moving away from the container. The two
surfaces 92 and 93 converge at a radially outward tip of thread 91
at curved portion 95. The corresponding closure thread 101 (see
FIG. 8A) is typically nonvented, has a rounded surface 102 at its
radially inward tip, and a substantially planar upper surface 103
(lower surface not shown).
[0064] In the prior art, the closure thread profile typically does
not match the profile of the neck finish thread at the region of
contact. When the closure 100 is applied to neck finish 90, the
surface 102 of closure thread 101 contacts neck finish thread 91 at
lower surface 93 at the underside of the finish thread 91,
resulting in a point contact at point 96 (in the cross-section)
between threads 91 and 101. In FIG. 8A, this point contact results
from the differing slopes of the substantially planar contacting
thread surfaces 93 and 103. As a result, any deformation of either
surface 93 or 103 that eliminates the point contact 96 would
compromise the seal between threads 91 and 101.
[0065] In contrast and in accordance with one embodiment of the
invention, a surface area contact is provided between the neck
finish and closure threads. Here, the closure and/or neck finish
threads to more closely approximate the profiles of the contacting
surfaces. In the embodiment of FIG. 8B, a lower surface of finish
thread 91 of neck finish 90 contacts an upper surface of thread 111
of closure 110. Thread 111 has a profile similar to that of thread
101 of FIG. 8A, except that the slope of upper planar surface 113
is changed to substantially match the slope of contacting surface
93 of finish thread 91. The matching slopes allow surface contact
between closure thread upper surface 113 and neck finish thread
lower surface 93, which enhances the seal between closure thread
111 and neck finish thread 91. In one embodiment, a plane of the
nonvented threads of the closure skirt contact a plane of the
vented threads of the neck finish to achieve the surface
contact.
[0066] In another embodiment, the surface 93 of neck finish thread
91 in FIG. 8B and the complementary surface 113 of closure thread
110 need not necessarily have flat profiles to achieve surface
contact. These complementary surfaces can engage via matching
curved planes, so long as more than point contact (e.g., surface
contact) is achieved.
[0067] In one embodiment, the contacting surfaces of the neck
finish thread and of the closure thread are both substantially
flat, having an angle with the horizontal of 100 or less. If the
matching flat surfaces approach the horizontal, the container
thread can penetrate (extend radially into) the closure threads to
a greater extent and achieve even greater surface contact. In
another embodiment, the matching flat surfaces of the container and
closure threads have an angle with the horizontal of 5.degree. or
less. In yet another embodiment, the matching flat surfaces of the
container and closure threads have an angle with the horizontal of
0.degree..
[0068] Another method of preventing thread deformation involves
thickening the finish thread. FIG. 8C shows a modification of a
neck finish thread 91 (e.g., the thread 91 of FIG. 8A) by providing
an additional thickness 99 on upper surface 92. This additional
thickness 99 (in the direction of the longitudinal container axis
A) strengthens neck finish thread 91 sufficiently that it is better
able to resist deformation. This embodiment allows the use of a
conventional closure and neck finish, where only the neck finish is
modified with an additional thickness 99. In one embodiment, at
least 10% is added to the finish thread thickness; in another
embodiment at least 20%, and in a further embodiment at least
30%.
[0069] In another embodiment, the ability to withstand deformation
by the neck finish threads can be increased by allowing the contact
between the neck and closure threads to occur at a distance closer
to the neck finish wall. FIG. 8A again is used to show a typical
contact point 96 between neck finish thread 91 and closure thread
101. The neck finish thread has a radial depth D (measured from
finish wall 97 to curved tip 95) and has a midpoint M. In FIG. 8A,
the point contact 96 occurs beyond the midpoint M and near the tip
95.
[0070] In contrast, in FIG. 8D the neck finish thread 91 has a
lower surface 93 that contacts the upper surface 123 of closure
thread 121 (of closure 120) at contact point 96. This is achieved
by an increased radial depth of closure thread 121 as compared to
the depth of closure thread 101 of FIG. 8A. The contact point 96 of
FIG. 8D now is in substantial radial alignment with the midpoint M
of neck finish thread 91. As a further example, in FIG. 8E the
contact point 96 between engaging surfaces 93 (of neck finish
thread 91) and 133 (of closure thread 131) occurs at a point
radially closer to the neck finish wall 97, i.e., before midpoint
M.
[0071] In one embodiment, providing a contact point radially closer
to the finish wall enhances the structural stability of the thread
because the "bending moment" of the (closure thread) force is
reduced. Bending moment is commonly used in solid mechanics to
evaluate stresses associated with cantilever beams. The finish
thread can be viewed as a cantilever element with the finish wall
being the fixed end and the outer edge being the "free" end. The
bending moment imposed on the (finish) thread at the wall of the
finish (fixed end) is proportional to the distance between the
point of contact (point at which the force is acting) and the wall
(fixed end). As the point of contact moves closer to the wall
(fixed end), this distance is reduced thereby reducing the bending
moment and in turn reducing the tendency to bend. Reduction of the
bending moment applies whether or not the thread thickens or
remains the same when moving from the outer edge of the thread
toward the finish wall.
[0072] In the embodiment where the thread thickness increases
toward the finish wall, moving the point contact 96 toward the neck
finish wall 97 can also improve thread integrity because the point
contact now occurs at an area of the neck finish thread 91 of
greater thickness. For example, in FIG. 8A the depth of the finish
thread is 0.057 inch, resulting in a contact point 96 at 0.016 inch
from the tip of the thread 95, providing a contact point at 28% the
depth of the thread (measured from the tip). In the embodiment of
FIG. 8D, point contact 96 occurs at a region where the neck finish
thread 91 has greater thickness, compared to the thickness shown in
FIG. 8A; in FIG. 8D the contact point 96 occurs at the midpoint
distance, i.e., at 0.028 inch, or 50% of the depth of the thread.
Still further, FIG. 8E shows an even more ideal situation where the
contact point 96 occurs at a distance of 0.037 inch from the tip
95, or 65% the depth of the thread. Accordingly, in one embodiment,
the contact point occurs at a distance of at least 50% of the
radial depth of the thread as measured from the tip of the thread
to the finish wall, e.g., at least 65%, alternatively at least 75%,
or even at least 85% of the depth of the thread as measured from
the tip of the thread.
[0073] Other methods can be used to manipulate the position of
point contact 96 to take advantage of the thicker thread region
near the finish wall. For example, the angle of the surface of the
underside of the finish thread (e.g., the surface 93 of finish
thread 91 in FIG. 8A) with the horizontal may be reduced to
increase the stability of the thread. The advantage of a flatter
thread may arise from the fact that the angle at which the
(closure) force acts on the finish thread becomes more vertical. By
itself the flatter thread does not change the bending moment.
However the vertical nature of the force due to flatness may allow
a more radially inward point of engagement between the contacting
neck and closure threads. It can also reduce the tendency of the
closure thread to "slide" (or strip) out of engagement. Typically,
the angle of the underside of the thread finish with the horizontal
is 20.degree.. In one embodiment of the invention, this angle is
less than 10.degree., or less than 5.degree.. In another
embodiment, this angle is 0.degree..
[0074] In another embodiment, deformation of the thread finish can
be prevented by using one or more of the techniques disclosed
herein. For example, the engagement between the finish and closure
threads can have surface contact that occurs at a region radially
closer to the finish wall to take advantage of the greater thread
thickness. In one embodiment where the finish and closure threads
contact via surface contact, the matching surfaces are flat. In one
embodiment, an extremity of the surface contact occurs at a
distance of at least 50% the depth of the thread as measured from
the tip of the thread to the finish wall. For example, in FIG. 8B
which shows surface contact, an extremity of the surface contact
occurs at a region between the finish wall and the midpoint of the
finish thread depth and thus, occurs at a distance greater than 50%
of the depth of the thread as measured from the tip of the thread
to the finish wall. The location of the other extremity is
generally not as relevant and can occur at a distance less than 50%
the depth of the thread. In another embodiment, an extremity of the
surface contact occurs at a distance of at least 65%, at least 75%,
or at least 85% the depth of the thread as measured from the tip of
the thread to the finish wall.
[0075] The dimensions of an exemplary finish and closure system
able to withstand pasteurization forces can, in one embodiment, be
determined by trial runs with closures of varying dimensions and
determining whether a test bottle containing fluid can withstand
typical pasteurization conditions. In another embodiment, the force
experienced by a bottle can be simulated with a test apparatus or
system 150, a cross-section of which is schematically depicted in
FIG. 9. System 150 includes an oven 152 enclosing a test fixture
154 for applying a force in the direction of the arrow 156. A test
finish 158 is supported on surface 160. Inner conical surface 162
of fixture 154 surrounds and contacts the annular top surface 159
of finish 158. Surface 162 is angled from the vertical to model the
direction of the force experienced by the finish 158 during
pasteurization (see e.g., FIGS. 2B and 2C), while applying an even
force to the top surface 159. FIG. 9 depicts the angle 164 from the
vertical to be 45.degree., although angle 164 may be different
depending on the dimensions of the neck finish and/or closure.
[0076] Advancing of the fixture 154 vertically downward in the
direction of arrow 156 is achieved with an air piston. Application
of a desired force to the top surface 159 of finish 158 may cause
finish 158 to bow inward, e.g., in the manner depicted in FIGS. 2B
and 2C. The force is calculated form the product of the area of the
piston multiplied by the pressure of the air. Monitoring
deformation of the finish (or lack of deformation) under an applied
force can guide one of ordinary skill in the art to determine the
appropriate dimensions of the closure that can substantially
prevent such deformation.
[0077] In one embodiment, the outer perimeter of the top surface
159 of the finish 158 experiences a force ranging from 63 lbs
(pounds) to 86 lbs applied at an angle 164 of 45.degree. to the
vertical plane. The corresponding horizontal component of these
forces translates to approximately 44.5 lbs to 60.8 lbs
respectively. For a top surface of the finish having an original
diameter of 0.982 inch, these forces can reduce the diameter of the
top surface of the finish by approximately 0.007 inch to 0.012
inch. As a result, the finish will have a frustocone shape. This
range or movement can cause the seal to fail, causing leakage. In
one embodiment, a closure having a rigid integral finish support
ring of a thickness of approximately 0.040 inch (e.g., finish
support ring 53 of FIG. 3) and a diameter of 0.844 inch can resist
the range of forces described above. In another embodiment, the
rigid external finish support ring extends to a vertical distance
of approximately 0.100 inch into the bottle finish (from the top
wall of the closure). Although the support ring may yield a small
amount when entering the neck of the finish (to achieve a tight fit
with the finish neck), the support ring remains sufficiently rigid
to prevent the diameter of the top surface of the finish from
reducing (moving in) by no more than 0.001 inch. In one embodiment,
the support ring is sufficiently rigid to maintain the original
diameter of the top surface of the finish even after
pasteurization, i.e., there is no reduction in diameter.
[0078] As used herein, "a thread" includes at least one thread or
thread segment. It is known to utilize a plurality of thread
segments, instead of a continuous thread, for one or more of a
closure thread and container thread.
[0079] As used herein, "a vented thread" means a thread having
interruptions, typically vertical cuts or gaps, which allow gas to
escape when a user opens the bottle (removes the closure). A
"nonvented thread" does not include such vents.
[0080] As used herein, "a polyester material" includes one or more
polyester homopolymers, copolymers, and blends thereof. The
material can include a variety of additives, as typically used in
the container industry. These additives may be polymer or
nonpolymer additives, and added for various purposes such as
processibility, intrinsic viscosity, gas barrier, etc. Similarly,
"a polyolefin material," or any other "material" is not limited to
a single polyolefin or a pure polyolefin. Preferably, a polyester
material would comprise at least 85% by weight of one or more
polyesters, more e.g., at least 90%, or even at least 95%.
[0081] A number of modifications and variations will readily
suggest themselves to persons of ordinary skill in the art in view
of the foregoing description. Directional words such as top,
bottom, upper, lower, and the like are employed by way of
description and not limitation. The invention is intended to
embrace all modifications and variations that fall within the scope
of the appended claims.
* * * * *