STRETCH ROD SYSTEM FOR LIQUID OR HYDRAULIC BLOW MOLDING
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Utility Application No.
13/267,979, filed on October 7, 201 1, and the benefit of U.S. Provisional
Application No. 61/393,41 1, filed on October 15, 201 0. The entire disclosures of
the above applications are incorporated herein by reference.
FIELD
[0002] This disclosure generally relates to forming a container for
retaining a commodity, such as a solid or liquid commodity. More specifically,
this disclosure relates to a centering device for use with a forming apparatus for
forming blown plastic containers that minimizes contamination and maintains a
preform in a desired orientation.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] As a result of environmental and other concerns, plastic
containers, more specifically polyester and even more specifically polyethylene
terephthalate (PET) containers are now being used more than ever to package
numerous commodities previously supplied in glass containers. Manufacturers
and fillers, as well as consumers, have recognized that PET containers are
lightweight, inexpensive, recyclable and manufacturable in large quantities.
[0005] Blow-molded plastic containers have become commonplace in
packaging numerous commodities. PET is a crystallizable polymer, meaning
that it is available in an amorphous form or a semi-crystalline form. The ability of
a PET container to maintain its material integrity relates to the percentage of the
PET container in crystalline form, also known as the "crystallinity" of the PET
container. The following equation defines the percentage of crystallinity as a
volume fraction:
% Crystallinity = — — ) 00
where p is the density of the PET material; pa is the density of pure amorphous
PET material ( 1 .333 g/cc); and p is the density of pure crystalline material
( 1 .455 g/cc).
[0006] Container manufacturers use mechanical processing and
thermal processing to increase the PET polymer crystallinity of a container.
Mechanical processing involves orienting the amorphous material to achieve
strain hardening. This processing commonly involves stretching an injection
molded PET preform along a longitudinal axis and expanding the PET preform
along a transverse or radial axis to form a PET container. The combination
promotes what manufacturers define as biaxial orientation of the molecular
structure in the container. Manufacturers of PET containers currently use
mechanical processing to produce PET containers having approximately 20%
crystallinity in the container's sidewalk
[0007] However, in some prior art configurations, preforms can
become damaged or unsanitized during mechanical processing. That is, in
some configurations, it has been found that preforms can become misaligned
with the mechanical device during stretching and consequently lead to
premature contact with the mold cavity and/or contact with other mechanical
devices. This misalignment thus can lead to defects and wastage.
[0008] In some cases, thermal processing is used which involves
heating the material (either amorphous or semi-crystalline) to promote crystal
growth. On amorphous material, thermal processing of PET material results in a
spherulitic morphology that interferes with the transmission of light. In other
words, the resulting crystalline material is opaque, and thus, generally
undesirable. Used after mechanical processing, however, thermal processing
results in higher crystallinity and excellent clarity for those portions of the
container having biaxial molecular orientation. The thermal processing of an
oriented PET container, which is known as heat setting, typically includes blow
molding a PET preform against a mold heated to a temperature of approximately
250°F - 350°F (approximately 12 1°C - 177°C), and holding the blown container
against the heated mold for approximately two (2) to five (5) seconds.
Manufacturers of PET juice bottles, which must be hot-filled at approximately
185°F (85 °C), currently use heat setting to produce PET bottles having an
overall crystallinity in the range of approximately 25% -35%.
SUMMARY
[0009] This section provides a general summary of the disclosure, and
is not a comprehensive disclosure of its full scope or all of its features.
[0010] According to the principles of the present disclosure, a mold
device and a method related thereto for forming a plastic container from a preform
is provided. The mold device comprises a mold defining a mold cavity, a stretch
initiation rod system for engaging an interior portion of the preform to define a
stretch initiation area, and a centrally disposed pressure source positionable within
the preform for introducing a pressurized fluid.
[0011] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples in this
summary are intended for purposes of illustration only and are not intended to
limit the scope of the present disclosure.
DRAWINGS
[0012] The drawings described herein are for illustrative purposes only
of selected embodiments and not all possible implementations, and are not
intended to limit the scope of the present disclosure.
[0013] FIGS. 1A-1 C illustrate a series of schematic side views
illustrating a central rod guiding a preform during the forming process (not to
scale);
[0014] FIG. 1D illustrates a schematic side view illustrating a slipped
condition of a central rod;
[0015] FIGS. 2A-2D illustrate a plurality of locating features according
to the principles of the present teachings;
[0016] FIGS. 3A-3B illustrate a stretch initiation rod being withdrawn
from a container to create a fluid headspace;
[0017] FIGS. 4A-4B illustrate a stretch initiation rod being inserted into
a container to create a fluid pressure spike;
[0018] FIG. 5A illustrates a mold device having a central rod according
to the present teachings; and
[0019] FIG. 5B illustrates a mold device having a centering feature
coupled with the central rod according to the present teachings.
[0020] Corresponding reference numerals indicate corresponding parts
throughout the several views of the drawings.
DETAILED DESCRIPTION
[0021] Example embodiments will now be described more fully with
reference to the accompanying drawings. Example embodiments are provided
so that this disclosure will be thorough, and will fully convey the scope to those
who are skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a thorough
understanding of embodiments of the present disclosure. It will be apparent to
those skilled in the art that specific details need not be employed, that example
embodiments may be embodied in many different forms and that neither should
be construed to limit the scope of the disclosure.
[0022] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be limiting. As used
herein, the singular forms "a", "an" and "the" may be intended to include the
plural forms as well, unless the context clearly indicates otherwise. The terms
"comprises," "comprising," "including," and "having," are inclusive and therefore
specify the presence of stated features, integers, steps, operations, elements,
and/or components, but do not preclude the presence or addition of one or more
other features, integers, steps, operations, elements, components, and/or groups
thereof. The method steps, processes, and operations described herein are not
to be construed as necessarily requiring their performance in the particular order
discussed or illustrated, unless specifically identified as an order of performance.
It is also to be understood that additional or alternative steps may be employed.
[0023] When an element or layer is referred to as being "on", "engaged
to", "connected to" or "coupled to" another element or layer, it may be directly on,
engaged, connected or coupled to the other element or layer, or intervening
elements or layers may be present. In contrast, when an element is referred to
as being "directly on," "directly engaged to", "directly connected to" or "directly
coupled to" another element or layer, there may be no intervening elements or
layers present. Other words used to describe the relationship between elements
should be interpreted in a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the term "and/or"
includes any and all combinations of one or more of the associated listed items.
[0024] Although the terms first, second, third, etc. may be used herein
to describe various elements, components, regions, layers and/or sections,
these elements, components, regions, layers and/or sections should not be
limited by these terms. These terms may be only used to distinguish one
element, component, region, layer or section from another region, layer or
section. Terms such as "first," "second," and other numerical terms when used
herein do not imply a sequence or order unless clearly indicated by the context.
Thus, a first element, component, region, layer or section discussed below could
be termed a second element, component, region, layer or section without
departing from the teachings of the example embodiments.
[0025] Spatially relative terms, such as "inner," "outer," "beneath",
"below", "lower", "above", "upper" and the like, may be used herein for ease of
description to describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. Spatially relative terms may
be intended to encompass different orientations of the device in use or operation
in addition to the orientation depicted in the figures. For example, if the device in
the figures is turned over, elements described as "below" or "beneath" other
elements or features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an orientation of
above and below. The device may be otherwise oriented (rotated 90 degrees or
at other orientations) and the spatially relative descriptors used herein
interpreted accordingly.
[0026] The present teachings provide for a stretch blow molding
machine having a centering device operable for engaging a preform container
during the molding process and a stretch initiation device operable to create a
stretch initiation area on the preform container. The stretch initiation device,
unlike molding machines, can be used to initiate the stretching of the preform
and encourage the preform to engage the centering device. The centering
device of the present teachings, unlike conventional molding machines, provides
improved control for maintaining the preform in a predetermined orientation to
minimize contact of the stretch rod to the preform, which could result in
contamination of the finished container.
[0027] As will be discussed in greater detail herein, the shape of the
container described in connection with the present teachings can be any one of
a number of variations. By way of non-limiting example, the container of the
present disclosure can be configured to hold any one of a plurality of
commodities, such as beverages, food, or other hot-fill type materials.
[0028] It should be appreciated that the size and the exact shape of
the centering device are dependent on the size and shape of the container to be
formed. Therefore, it should be recognized that variations can exist in the
presently described designs.
[0029] The present teachings relate to the forming of one-piece plastic
containers. Generally, these containers, after formation, generally define a body
that includes an upper portion having a cylindrical sidewall forming a finish.
Integrally formed with the finish and extending downward therefrom is a shoulder
portion. The shoulder portion merges into and provides a transition between the
finish and a sidewall portion. The sidewall portion extends downward from the
shoulder portion to a base portion having a base. An upper transition portion, in
some embodiments, may be defined at a transition between the shoulder portion
and the sidewall portion. A lower transition portion, in some embodiments, may
be defined at a transition between the base portion and the sidewall portion.
[0030] The exemplary container may also have a neck. The neck may
have an extremely short height, that is, becoming a short extension from the
finish, or an elongated height, extending between the finish and the shoulder
portion. The upper portion can define an opening. Although the container is
shown as a drinking container and a food container, it should be appreciated that
containers having different shapes, such as sidewalls and openings, can be
made according to the principles of the present teachings.
[0031] The finish of the plastic container may include a threaded
region having threads, a lower sealing ridge, and a support ring. The threaded
region provides a means for attachment of a similarly threaded closure or cap
(not illustrated). Alternatives may include other suitable devices that engage the
finish of the plastic container, such as a press-fit or snap-fit cap for example.
Accordingly, the closure or cap (not illustrated) engages the finish to preferably
provide a hermetical seal of the plastic container. The closure or cap (not
illustrated) is preferably of a plastic or metal material conventional to the closure
industry and suitable for subsequent thermal processing.
[0032] The container can be formed according to the principles of the
present teachings. A preform version of the container can include a support ring,
which may be used to carry or orient the preform through and at various stages
of manufacture. For example, the preform may be carried by the support ring,
the support ring may be used to aid in positioning the preform in a mold cavity, or
the support ring may be used to carry an intermediate container once molded.
At the outset, the preform may be placed into the mold cavity such that the
support ring is captured at an upper end of the mold cavity.
[0033] In general, as illustrated in FIGS. 5A and 5B, the mold 300 can
comprise a mold cavity 302 having an interior surface 304 corresponding to a
desired outer profile of the blown container. More specifically, the mold cavity
according to the present teachings defines a body forming region, an optional
moil forming region and an optional opening forming region. Once the resultant
structure, hereinafter referred to as an intermediate container, has been formed
in some embodiments, any moil created by the moil forming region may be
severed and discarded. It should be appreciated that the use of a moil forming
region and/or opening forming region are not necessarily in all forming methods
or according to all embodiments of the present teachings.
[0034] In one example, a machine places the preform heated to a
temperature between approximately 190°F to 250 °F (approximately 88 °C to
12 1 °C) into the mold cavity. The mold cavity may be heated to a temperature
between approximately 250°F to 350°F (approximately 12 1 °C to 177°C). An
internal stretch rod apparatus can stretch or extend the heated preform within
the mold cavity to a length approximately that of the intermediate container
thereby molecularly orienting the polyester material in an axial direction generally
corresponding with the central longitudinal axis of the container. While the
stretch rod extends the preform, fluid (e.g. liquid, such as the final liquid
commodity; air; and the like) from a centrally disposed pressure source, having a
pressure between 300 PSI to 600 PSI (2.07 MPa to 4.1 4 MPa), assists in
extending the preform in the axial direction and in expanding the preform in a
circumferential or hoop direction thereby substantially conforming the polyester
material to the shape of the mold cavity and further molecularly orienting the
polyester material in a direction generally perpendicular to the axial direction,
thus establishing the biaxial molecular orientation of the polyester material in
most of the intermediate container. The pressurized fluid holds the mostly
biaxial molecularly oriented polyester material against the mold cavity for a
period of approximately two (2) to five (5) seconds before removal of the
intermediate container from the mold cavity. This process is known as heat
setting and results in a heat-resistant container suitable for filling with a product
at high temperatures.
[0035] With particular reference to FIGS. 1A-4B, stretch blow molding
systems can employ a central interior stretch initiation rod system 20 that can
engage an interior feature or surface of a preform 112 and/or a central exterior
rod system 100 that can engage an exterior feature 110, or other portion, of the
preform 112. It should be appreciated that according to the principles of the
present teachings, central interior stretch initiation rod system 20 and central
exterior rod system 100 can be used separately or in combination. Moreover,
central interior stretch initiation rod system 20 and central exterior rod system
100 can be used independently and/or simultaneously.
[0036] With particular reference to FIGS. 1A, 3A, 3B, 4A, and 4B, in
some embodiments, stretch initiation rod system 20 can be raised and lowered
relative to preform 112 to provide a mechanical urging force against an interior
surface of preform 112. Stretch initiation rod system 20 can comprise a rod
member 22 having a distal tip 24, an elongated shaft 26, and a drive system 28
coupled to the elongated shaft 26 to actuate distal tip 24 between a retracted
(see FIGS. 3B and 4A) and an extended (see FIGS. 1A, 3A, and 4B) position.
Drive system 28 can comprise a pneumatic drive system, a servo drive system,
or other known system for creating motion of rod member 22. In some
embodiments, drive system 28 includes a servo or positive stop to provide
positioning information. Moreover, in some embodiments, drive system 28 can
be used for real-time tracking a position and/or drive speed of rod member 22 to
provide real-time control. Still further, it should be appreciated that although rod
member 22 is described and illustrated as being cylindrical with a rounded tip,
other shapes and tips are envisioned, including but not limited to conical, non
uniform, tapered, pointed, flattened, and the like or can be varied to define a
predetermined volume.
[0037] It should be noted, however, that stretch initiation rod system 20
can be separate from or joined with a typical central rod of a blow molding
system. That is, a stretch initiation rod system 20 can be separately formed or
integrally formed with the central rod. Stretch initiation rod system 20 can,
however, employ distal tip 24 to engage or otherwise contact preform 112 to
define the stretch initiation area and/or prestretch. By way of non-limiting
example, prestretches of about 40 mm have been found to be beneficial,
however other prestretch lengths, such as the distance X of FIG. 1A, may be
appropriate. This insures a known stretching response and material distribution
during molding, rather than the unpredictable stretching response common with
conventional molding systems. This material distribution can include non
uniform distribution for predetermined design criteria.
[0038] With reference to FIGS. 1A-1 D, central exterior rod system 100
can be used, ideally, to maintain preform 112 in a predetermined orientation
during the stretch blow forming process as illustrated in FIGS. 1A-1 C. Central
interior stretch initiation rod 20 can be used, ideally, to initiate the forming
process. In this way, the preform 112 is initially stretched to achieve a
predetermined molding response using stretch initiation rod system 20 and then
centrally maintained by central exterior rod system 100 relative to the stretch rod
and/or stretch initiation rod system 20 extending therein, thereby ensuring that
the stretch rod(s) does not contact the inside of the preform. Such contact of the
stretch rod within the preform can cause contamination of the resultant
container, thereby requiring the resultant container to be discarded or sanitized.
[0039] In some embodiments, stretch initiation rod system 20 can be
used to achieve a precise headspace within the final filled container.
Specifically, as seen in FIGS. 3A-3B, stretch initiation rod system 20 can be
actuated and/or sized such that following formation of the preform 112 into the
final container (which is done with the final fill commodity), retraction of rod
member 22 can represent a precise volume (that is, the volume of rod member
22 disposed within the final fill commodity) that when retracted provides the
desired headspace for packaging and shipment. Such precise headspace is
achieved without complex valve systems and the like.
[0040] Moreover, in some embodiments, stretch initiation rod system
20 can be used to achieve a fluid pressure spike to aid in the shaping of preform
112 or container. Specifically, as seen in FIGS. 4A-4B, stretch initiation rod
system 20 can be actuated such that the fluid volume displaced by rod member
22 is greater than a headspace within the preform 112 or finished bottle, such
that insertion of rod member 22 into the preform 112 or container, having a
contained and generally fixed volume, causes a pressure spike within the
preform 112 or container. Such pressure spikes can be used to define final
details within the preform 112 or container.
[0041] Turning now to FIG. 1D, in some embodiments, preform 112
may form in such a way as to slip off or become disengaged from the central
exterior rod system 100. This can often lead to damage to the preform by
contact with the central exterior rod system 100 and/or contamination with the
internal stretch rod.
[0042] To overcome this issue, with reference to FIGS. 2A-2D, in some
embodiments, central exterior rod system 100 can comprise a locating feature
120 for engaging or otherwise contacting the preform 112. Locating feature 120
can comprise, in some embodiments, a protruding portion 122 defining a first
shape. A corresponding depression 124, having a complementary shape to the
first shape, can be formed as part of preform 112. In this way, protruding portion
122 can be positively received within depression 124 to define a reliable
connection therebetween. In some embodiments, protruding portion 122 is sized
and shaped to closely conform to depression 124 to minimize lateral movement
(that is, movement in a hoop direction). The shape of protruding portion 122,
and consequently depression 124, can be cylindrical (FIGS. 2A and 2B), tapered
(FIGS. 2C and 2D), wide (FIG. 2C), narrow (FIGS. 2B and 2D), or any other
shape/size that provides a reliable connection between central exterior rod
system 100 and preform 112. It should be appreciated that locating feature 120
can define a reverse orientation (indicated with similar primed reference
numbers) to those already described in that the locating feature 120 can
comprise a protruding portion extending from the preform (FIGS. 2C and 2D) for
engaging a depression formed in the central exterior rod system 100.
[0043] Still further, in some embodiments as illustrated in FIGS. 5A-5B,
central exterior rod system 100 can extend from mold device 200 as a generally
cylindrical member (FIG. 5A) or can include a centering feature 2 10 located
along a portion of central exterior rod system 100. In some embodiments,
centering feature 2 10 can be an oversized head member 2 11 disposed on distal
end 2 12 of central exterior rod system 100. In some embodiments, the
oversized member can include a tapered portion 214, such as conical portion,
that is sized to be received and/or captured within a conical depression 2 16
formed in the mold device 200. In this way, upon retraction of central exterior
rod system 100, tapered portion 2 14 can be centrally received within conical
depression 2 16 to ensure proper aligned of the now-expand preform 112 or
resultant container. It should also be recognized that in some embodiments,
oversized head member 2 11 can be shaped to form part of the mold device and,
at least in part, impart a shape upon preform 112 during formation of the
resultant container.
[0044] Alternatively, other manufacturing methods, such as for
example, extrusion blow molding, one step injection stretch blow molding and
injection blow molding, using other conventional materials including, for example,
thermoplastic, high density polyethylene, polypropylene, polyethylene
naphthalate (PEN), a PET/PEN blend or copolymer, and various multilayer
structures may be suitable for the manufacture of plastic containers and used in
connection with the principles of the present teachings.
[0045] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not intended to be
exhaustive or to limit the invention. Individual elements or features of a
particular embodiment are generally not limited to that particular embodiment,
but, where applicable, are interchangeable and can be used in a selected
embodiment, even if not specifically shown or described. The same may also be
varied in many ways. Such variations are not to be regarded as a departure from
the invention, and all such modifications are intended to be included within the
scope of the invention.

CLAIMS
What is claimed is:
1. A mold device for forming a plastic container from a preform, said
mold device comprising:
a mold defining a mold cavity for receiving the preform;
a stretch initiation rod system operably coupled with said mold
cavity, said stretch initiation rod system engaging an interior portion of the
preform to define a stretch initiation area; and
a centrally disposed pressure source fluidly coupled to said mold
cavity, said centrally disposed pressure source positionable within the preform for
introducing a pressurized fluid.
2. The mold device according to Claim 1 wherein said stretch initiation
rod system comprises an elongated member and a tip portion, said tip portion
contacting said interior portion of the preform.
3. The mold device according to Claim 2 wherein said stretch initiation
rod system comprises a drive system actuating said elongated member and said
tip portion between an extended position in contact with the preform and a
retracted position.
4 . The mold device according to Claim 3 wherein said actuation of said
elongated member and said tip portion result in a fluid pressure change within the
preform.
5. The mold device according to Claim 3 wherein said actuation of said
elongated member and said tip portion results in creation of a fluid headspace
within the plastic container.
6. The mold device according to Claim 1, further comprising:
a central exterior rod having a locating feature formed therewith, said
locating feature engaging an exterior feature of the preform for maintaining a
central orientation of the preform during forming.
7. The mold device according to Claim 6 wherein said locating feature
of said central exterior rod comprises a protrusion extending therefrom, said
protrusion being sized and shaped to closely conform to the exterior feature of the
preform.
8. The mold device according to Claim 7 wherein said protrusion is
cylindrically shaped.
9. The mold device according to Claim 7 wherein said protrusion is
tapered.
10. The mold device according to Claim 6 wherein said locating feature
of said central exterior rod comprises a depression formed therein, said depression
being sized and shaped to closely receive the exterior feature of the preform
therein.
11. The mold device according to Claim 10 wherein said depression is
cylindrically shaped.
12. The mold device according to Claim 10 wherein said depression is
tapered.
13. A mold device for forming a plastic container from a preform, said
mold device comprising:
a mold defining a mold cavity for receiving the preform;
a pressure source fluidly coupled to said mold cavity, said pressure
source positionable within the preform for introducing a pressurized fluid;
a stretch initiation rod system operably coupled with said mold
cavity, said stretch initiation rod system engaging an interior portion of the
preform to define a stretch initiation area; and
a central exterior rod having a locating feature formed therewith, said
locating feature engaging an exterior feature of the preform for maintaining a
central orientation of the preform during forming.
14. The mold device according to Claim 13 wherein said stretch initiation
rod system comprises an elongated member and a tip portion, said tip portion
contacting said interior portion of the preform.
15. The mold device according to Claim 14 wherein said stretch initiation
rod system comprises a drive system actuating said elongated member and said
tip portion between an extended position in contact with the preform and a
retracted position.
16. The mold device according to Claim 15 wherein said actuation of
said elongated member and said tip portion result in a fluid pressure change within
the preform or filled plastic container.
17. The mold device according to Claim 15 wherein said actuation of
said elongated member and said tip portion results in creation of a fluid headspace
within the plastic container.
18. The mold device according to Claim 13 wherein said locating feature
of said central exterior rod comprises a protrusion extending therefrom, said
protrusion being sized and shaped to closely conform to the exterior feature of the
preform.
19. The mold device according to Claim 18 wherein said protrusion is
cylindrically shaped.
20. The mold device according to Claim 18 wherein said protrusion is
tapered.
2 1. The mold device according to Claim 13 wherein said locating feature
of said central exterior rod comprises a depression formed therein, said depression
being sized and shaped to closely receive the exterior feature of the preform
therein.
22. The mold device according to Claim 2 1 wherein said depression is
cylindrically shaped.
23. The mold device according to Claim 2 1 wherein said depression is
tapered.
24. The mold device according to Claim 13, further comprising:
a centering feature being disposed on a portion of said central
exterior rod, said centering feature being engagable with said mold to align said
central exterior rod with said mold in at least a retracted position.
25. The mold device according to Claim 24 wherein said centering
feature is conically shaped.
26. A method of forming a plastic container from a preform, said method
comprising:
heating a preform to a temperature between 190 °F and 250 °F;
heating a mold cavity to a temperature between 250 °F and 350 °F;
inserting said preform within said mold cavity;
actuating a stretch initiation rod system to engage an interior
portion of the preform to define a stretch initiation area;
introducing a pressurized fluid into said preform to expand said
preform to closely conform to said mold cavity; and
actuating a central exterior rod such that a locating feature formed on
said central exterior rod engages an exterior feature of said preform to generally
maintain a predetermined orientation of said preform during at least a portion of
said introducing said pressurized fluid.
27. The method according to Claim 26, further comprising:
actuating said stretch initiation rod system following at least a
portion of said introducing said pressurized fluid to create a headspace within the
container.
28. The method according to Claim 26, further comprising:
actuating said stretch initiation rod system following at least a
portion of said introducing said pressurized fluid to create a fluid pressure spike
within the container.
29. The method according to Claim 26, further comprising:
maintaining a predetermined pressure within said preform following
said introducing said pressurized fluid such that said preform is held against said
mold cavity for a predetermined duration.
30. The method according to Claim 29 wherein said predetermined
duration is between 0.1 seconds and 1.5 seconds.
3 1. The method according to Claim 26 wherein said pressurized fluid
comprises a liquid commodity that remains in the plastic container.
32. The method according to Claim 26 wherein said preform is made
from a thermoplastic, a high density polyethylene, a polypropylene, a polyethylene
naphthalate (PEN), a PET/PEN blend, a copolymer, various multilayer structures,
and any combination or blend thereof.