U.S. patent application number 13/251830 was filed with the patent office on 2013-04-04 for plastic aerosol container assembly and method of making.
This patent application is currently assigned to GRAHAM PACKAGING COMPANY, L.P.. The applicant listed for this patent is RALPH ARMSTRONG, KEITH J. BARKER, BRIAN A. LYNCH, THOMAS E. NAHILL. Invention is credited to RALPH ARMSTRONG, KEITH J. BARKER, BRIAN A. LYNCH, THOMAS E. NAHILL.
Application Number | 20130082074 13/251830 |
Document ID | / |
Family ID | 47178288 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130082074 |
Kind Code |
A1 |
ARMSTRONG; RALPH ; et
al. |
April 4, 2013 |
PLASTIC AEROSOL CONTAINER ASSEMBLY AND METHOD OF MAKING
Abstract
A plastic aerosol container assembly includes a plastic
container that has a main body portion defining an interior space
and a finish portion that defines an opening. A pressurized aerosol
mixture is maintained within the interior space. The finish portion
has an inner surface that has an undercut defined therein. An
aerosol valve assembly is mounted to the plastic container so that
a portion thereof engages the inner surface of the finish portion
so as to be retained by the undercut. The plastic container is
preferably fabricated from material including polyethylene
terephthalate. At least one location in the finish portion may be
crystallized in order to provide enhanced resistance to stress
cracking.
Inventors: |
ARMSTRONG; RALPH; (WESTON,
CT) ; NAHILL; THOMAS E.; (AMHERST, NH) ;
BARKER; KEITH J.; (BEDFORD, NH) ; LYNCH; BRIAN
A.; (MERRIMACK, NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ARMSTRONG; RALPH
NAHILL; THOMAS E.
BARKER; KEITH J.
LYNCH; BRIAN A. |
WESTON
AMHERST
BEDFORD
MERRIMACK |
CT
NH
NH
NH |
US
US
US
US |
|
|
Assignee: |
GRAHAM PACKAGING COMPANY,
L.P.
YORK
PA
|
Family ID: |
47178288 |
Appl. No.: |
13/251830 |
Filed: |
October 3, 2011 |
Current U.S.
Class: |
222/402.1 ;
264/531 |
Current CPC
Class: |
B29C 49/06 20130101;
B29K 2067/003 20130101; B65D 83/44 20130101; B65D 83/38
20130101 |
Class at
Publication: |
222/402.1 ;
264/531 |
International
Class: |
B65D 83/00 20060101
B65D083/00; B29C 49/00 20060101 B29C049/00 |
Claims
1. A plastic aerosol container assembly, comprising: a plastic
container having a main body portion defining an interior space and
a finish portion defining an opening, the finish portion having an
inner surface that has an undercut defined therein; and an aerosol
valve assembly mounted to the plastic container, the aerosol valve
assembly having a portion that engages the inner surface of the
finish portion so as to be retained by the undercut.
2. A plastic aerosol container assembly according to claim 1,
wherein the aerosol valve assembly is seated against the
undercut.
3. A plastic aerosol container assembly according to claim 1,
wherein the plastic container is fabricated from a material
comprising polyethylene terephthalate.
4. A plastic aerosol container assembly according to claim 3,
wherein the material comprising polyethylene terephthalate is
crystallized at least one location within the finish portion.
5. A plastic aerosol container assembly according to claim 1,
wherein the finish portion has a longitudinal axis, and wherein the
undercut is oriented within a transverse plane that is
substantially perpendicular to the longitudinal axis.
6. A plastic aerosol container assembly according to claim 1,
wherein the undercut extends substantially along an entire inner
circumference of the inner surface of the finish portion.
7. A plastic aerosol container assembly according to claim 1,
wherein the aerosol valve assembly is not directly secured to an
outer surface of the finish portion.
8. A plastic aerosol container assembly according to claim 1,
further comprising a pressurized aerosol mixture within the plastic
container.
9. A plastic aerosol container, comprising: a main body portion
defining an interior space; and a finish portion that is unitary
with the main body portion and has an inner surface that has an
undercut defined therein.
10. A plastic aerosol container according to claim 9, wherein the
main body portion and a finish portion are fabricated from a
material comprising polyethylene terephthalate.
11. A plastic aerosol container according to claim 10, wherein the
material comprising polyethylene terephthalate is crystallized at
least one location within the finish portion.
12. A plastic aerosol container according to claim 9, wherein the
finish portion has a longitudinal axis, and wherein the undercut is
oriented within a transverse plane that is substantially
perpendicular to the longitudinal axis.
13. A plastic aerosol container assembly according to claim 9,
wherein the undercut extends substantially along an entire inner
circumference of the inner surface of the finish portion.
14. A plastic aerosol container, comprising: a main body portion
defining an interior space; and a finish portion that is unitary
with the main body portion, and wherein the main body portion and
the finish portion are fabricated from a material comprising
polyethylene terephthalate, and wherein at least a portion of the
finish portion is crystallized.
15. A plastic aerosol container according to claim 14, wherein the
finish portion has an inner surface that has an undercut defined
therein.
16. A plastic aerosol container according to claim 15, wherein the
finish portion has a longitudinal axis, and wherein the undercut is
oriented within a transverse plane that is substantially
perpendicular to the longitudinal axis.
17. A plastic aerosol container according to claim 15, wherein the
undercut extends substantially along an entire inner circumference
of the inner surface of the finish portion.
18. A method of forming a plastic aerosol container, comprising
steps of: (a) providing a preform having a finish portion; (b) blow
molding a plastic container from the preform; and (c) reforming the
finish portion so that an inner surface thereof has an undercut
defined therein, and wherein step (c) is performed at some point
after step (a).
19. A method of forming a plastic aerosol container according to
claim 18, wherein step (c) is performed after step (b).
20. A method of forming a plastic aerosol container according to
claim 18, wherein the preform having the finish portion is formed
by injection molding, and wherein step (c) is performed by
reheating the finish portion and reshaping the finish portion using
a mechanical tool.
21. A method of forming a plastic aerosol container according to
claim 18, wherein step (c) is performed by shaping the undercut so
that it is oriented within a transverse plane that is substantially
perpendicular to a longitudinal axis of the finish portion.
22. A method of forming a plastic aerosol container according to
claim 18, wherein step (c) is performed by shaping the undercut so
that the undercut extends substantially along an entire
circumference of the inner surface of the finish portion.
23. A method of forming a plastic aerosol container according to
claim 18, wherein the preform is fabricated from a material
comprising polyethylene terephthalate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates broadly to the field of containers
that are adapted to hold highly pressurized contents, such as
aerosol mixtures, and more particularly to a blow molded plastic
aerosol container having a finish portion that is constructed and
arranged to provide an optimal seal to an aerosol valve
assembly.
[0003] 2. Description of the Related Technology
[0004] Aerosol containers have conventionally been fabricated from
metal, and are conventionally formed as a cylindrical tube having
upper and lower end closures. The bottom end closure is typically
shaped as a concave dome, and the upper end closure typically
includes a manually actuatable valve for dispensing the pressurized
aerosol contents of the container.
[0005] Metallic containers have certain inherent disadvantages,
such as a tendency to rust over time and to scratch surfaces with
which they may come into contact.
[0006] Efforts have been made in the past to develop plastic
aerosol containers, but have encountered difficulties, mainly
relating to controlling the deformation of the plastic material as
a result of the significant internal pressurization that is
necessary in an aerosol container. Aerosol containers commonly
require internal pressures of the magnitude of 50-300 psi, which is
significantly greater than pressures that are typically encountered
in other packaging applications for which plastic material has been
used, such as the packaging of carbonated beverages. Accordingly,
design considerations for plastic aerosol containers are quite
different than they are for lower pressure packaging applications
such as plastic beverage containers.
[0007] One common type of plastic container is fabricated from a
material such as polyethylene terephthalate (PET) and is
manufactured from an injection molded preform having a threaded
finish portion using the reheat stretch blow molding process. While
such containers hold some promise for aerosol applications, they
are susceptible to stress cracking in the finish portion while
under pressurization. In addition, the finish portion of such
containers has a tendency to deform when the container is
pressurized, possibly resulting in a loss of sealing integrity
between the container and the aerosol dispensing closure.
[0008] The preforms that are used in the reheat stretch blow
molding process typically include a finish portion that remains
substantially unchanged in shape as a result of the blow molding
process. The finish portion includes the upper rim of the container
that defines the container opening. Typically, the aerosol valve
assembly that is required in plastic aerosol containers has been
attached to the outer surface of the finish portion, which may be
provided with external threading or one or more mounting flanges.
In metal aerosol containers, it is considered preferable to mount
the valve assembly to an inside surface of the upper portion of the
container. An inside seal has inherent mechanical advantages over
an outside seal, but those in the field have considered an inside
seal to be impractical for plastic aerosol containers because of
the difficulty of mounting a valve assembly to the inner surface of
the finish portion of a blow molded plastic container. The inner
surface of the finish portion in such a container tends to be
smooth, with no features that would enable a valve assembly to gain
the necessary purchase in order to prevent dislodgement.
[0009] A need exists for an improved blow molded plastic aerosol
container assembly that provides a more effective mount and seal
between the finish portion of the plastic container and an aerosol
valve assembly.
SUMMARY OF THE INVENTION
[0010] Accordingly, it is an object of the invention to provide an
improved blow molded plastic aerosol container assembly that
achieves a more effective mount and seal between the finish portion
of the plastic container and an aerosol valve assembly.
[0011] In order to achieve the above and other objects of the
invention, a plastic aerosol container assembly according to a
first aspect of the invention includes a plastic container having a
main body portion defining an interior space and a finish portion
that defines an opening. The finish portion has an inner surface
that has an undercut defined therein. The container assembly
further includes an aerosol valve assembly mounted to the plastic
container that has a portion that engages the inner surface of the
finish portion so as to be retained by the undercut.
[0012] A plastic aerosol container according to a second aspect of
the invention includes a main body portion defining an interior
space; and a finish portion that is unitary with the main body
portion and has an inner surface that has an undercut defined
therein.
[0013] A plastic aerosol container according to a third aspect of
the invention includes a main body portion defining an interior
space; and a finish portion that is unitary with the main body
portion. The main body portion and the finish portion are
fabricated from a material comprising polyethylene terephthalate.
At least a portion of the finish portion is crystallized.
[0014] A method of forming a plastic aerosol container according to
a fourth aspect of the invention includes steps of (a) providing a
preform having a finish portion; (b) blow molding a plastic
container from the preform; and (c) reforming the finish portion so
that an inner surface thereof has an undercut defined therein, and
wherein step (c) is performed at some point after step (a).
[0015] These and various other advantages and features of novelty
that characterize the invention are pointed out with particularity
in the claims annexed hereto and forming a part hereof. However,
for a better understanding of the invention, its advantages, and
the objects obtained by its use, reference should be made to the
drawings which form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side elevational view of a plastic aerosol
container assembly that is constructed according to a preferred
embodiment of the invention;
[0017] FIG. 2 is a fragmentary cross-sectional view showing a first
step in a method that is performed according to the preferred
embodiment of the invention;
[0018] FIG. 3 is a fragmentary cross-sectional view showing a
second step in a method that is performed according to the
preferred embodiment of the invention;
[0019] FIG. 4 is a fragmentary cross-sectional view showing a third
step in a method that is performed according to the preferred
embodiment of the invention;
[0020] FIG. 5 is a fragmentary cross-sectional view showing a
fourth step in a method that is performed according to the
preferred embodiment of the invention; and
[0021] FIG. 6 is a fragmentary cross-sectional view showing a
portion of the plastic aerosol container assembly that is depicted
in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0022] Referring now to the drawings, wherein like reference
numerals designate corresponding structure throughout the views,
and referring in particular to FIG. 1, a plastic aerosol container
assembly 10 that is constructed according to a preferred embodiment
of the invention includes a main body portion 12 that defines an
interior space in which a pressurized aerosol mixture 30 is
preferably provided.
[0023] The plastic aerosol container assembly 10 further includes a
neck finish portion 14 and a bottom portion 18. Both the finish
portion 14 and the bottom portion 18 are preferably unitary with
the main body portion 12. The main body portion 12 and the bottom
portion 18 are preferably blow molded from a plastic preform using
the reheat stretch blow molding process.
[0024] The main body portion 12, finish portion 14 and bottom
portion 18 are preferably fabricated from a plastic material such
as polyethylene terephthalate (PET), polyethylene naphthalate
(PEN), acrilonitrile (AN), polycarbonate (PC), polyamide (Nylon),
or a blend containing some combination of the same from a plastic
preform using a conventional blow molding process such as the
reheat stretch blow molding process. In the preferred embodiment,
the plastic container is fabricated from a high intrinsic viscosity
polyethylene terephthalate material, which most preferably has an
intrinsic viscosity that is substantially within a range of about
0.76 to about 0.95.
[0025] The main body portion 12 is preferably constructed and
arranged to withstand aerosol pressurization within a range of
about 50 psig to about 300 psig. More preferably, the main body
portion 12 is constructed and arranged to withstand aerosol
pressurization within a range of about 120 psig to about 180 psig.
The container assembly 10 is preferably pressurized with an aerosol
mixture 30 at a range of pressurization that is substantially
between about 50 psig to about 300 psig, and more preferably
substantially within a range of about 120 psig to about 180
psig.
[0026] The aerosol mixture 30 preferably includes a propellant,
which could be a liquefied gas propellant or a compressed or
soluble gas propellant. Liquefied gas propellants that could be
used include hydrocarbon propellants such as propane, isobutene,
normal butane, isopentane, normal pentane and dimethyl ether, and
hydrofluorocarbon propellants such as difluoroethane (HFC-152a) and
tetrafluoroethane (HFC-134a). Compressed and soluble gas
propellants that could be used include carbon dioxide (C02),
nitrous oxide (N20), nitrogen (N2) and compressed air.
[0027] The finish portion 14 preferably has an inner surface 20
that has an undercut 22 defined therein, as is best shown in FIG.
4. An aerosol valve assembly 24 is seated against the undercut 22,
as is best shown in FIG. 6. Accordingly, the aerosol valve assembly
24 forms an inside seal with respect to the finish portion 14. The
aerosol valve assembly 24 in the preferred embodiment is not
directly secured to an outer surface of the finish portion 14.
[0028] The finish portion 14 has a longitudinal axis 32, and the
undercut 22 is preferably oriented within a volume that is
equidistant about a transverse plane 28 that is substantially
perpendicular to the longitudinal axis 32. In other words, the
undercut 22 preferably has a substantially horizontal orientation.
This is best shown in FIG. 4. In addition, the undercut 22
preferably extends substantially along an entire inner
circumference of the inner surface 20 of the finish portion 14.
[0029] Preferably, the plastic material forming the finish portion
14 is crystallized in at least one location within the finish
portion 14. The crystallization could be throughout the entire
finish portion 14, or in selected portions of the finish portion
14. For example, crystallization could be performed so that
substantial crystallization is achieved in at least a first portion
of the finish portion 14, substantially no crystallization in a
second portion of finish portion 14 and graded crystallization
between the first and second portions of the finish portion 14. The
term "graded crystallization" refers to a gradual transition
between substantial crystallization and substantially no
crystallization, as distinguished from a sharp or distinct
non-graded pattern of contrast between crystallized and
uncrystallized portions of the neck finish. The gradation of
crystallization is continuous, and may be either linear or
non-linear with distance. Such crystallization in a container neck
finish is taught in U.S. Pat. 7,033,656 to Nahill et al., the
entire disclosure of which is hereby incorporated by reference as
if set forth fully herein.
[0030] A method of forming a plastic aerosol container assembly 10
according to a preferred embodiment of the invention is depicted in
FIGS. 2-6. Referring to FIG. 2, the finish portion 14 of the
container after it has been shaped by the blow molding process
typically has an inner surface 40 that is substantially smooth and
vertical, with an upper rim 42. Advantageously, the finish portion
14 shown in FIG. 2 is reformed according to the preferred
embodiment of the invention so that the inner surface will have the
undercut that is shown in FIG. 4.
[0031] Heat is preferably applied to the finish portion 14 that is
shown in FIG. 2 in order to soften the plastic material. The finish
portion 14 is preferably heated to a temperature that is
substantially within a range of about 280 degrees F. to about 370
degrees F., and more preferably substantially within a range of
about 300 degrees F. to about 350 degrees F. Heating time is
preferably substantially within a range of about 20 seconds to
about 65 seconds, and more preferably substantially within a range
of about 30 seconds to about 55 seconds.
[0032] Subsequently, a shaping tool 46 is used to urge the upper
rim 42 radially inwardly and downward, so that the upper rim 42 and
the inside surface 40 achieve the shape that is depicted in FIG. 4.
As FIG. 4 shows, the finish portion 14 at this stage of the process
includes an upper rim 33 that transitions to the inner surface 20
so as to define a radially inwardly extending convex lip 34 and a
radially outwardly extending concave recess 36 that is positioned
immediately beneath the radially inwardly extending convex lip
34.
[0033] FIG. 5 depicts a blank aerosol valve assembly 24 being
inserted into the opening defined by the upper lip 33 of the finish
portion 14 that is shown in FIG. 4. The aerosol valve assembly 24
preferably includes a metallic panel 48 to which an aerosol valve
stem 26 is mounted. The metallic panel 48 includes an annular
downwardly extending portion 50 that includes an outer wall portion
52, which is oriented so as to be substantially straight and
vertical, permitting convenient insertion of the blank aerosol
valve assembly 24 into the opening. The metallic panel 48 also
preferably includes a flange portion 54 that is congruent with and
seals against the upper rim 33 and the convex lip 34 of the finish
portion 14.
[0034] A tool is used to crimp the outer wall portion 52 outwardly
into the position that is shown in FIG. 6, in which the inward
crimp 56 is seated securely against the undercut 22, firmly
securing the aerosol valve assembly 24 against dislodgement from
the finish portion 14 as a result of the internal pressurization of
the container. Such an inside seal is mechanically preferable to
outside seals that have heretofore been used in plastic aerosol
container assemblies.
[0035] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *