Container having expandable neck

Details Container having expandable neck Container having expandable neck

2002-06-25

2004-04-27

Weaver, Sue A. (Department: 3727)

Bottles and jars

Sidewall structure

Pressure-responsive structure

C215S040000

Reexamination Certificate

active

06726044

ABSTRACT:

BACKGROUND
The present invention relates to plastic containers, and more particularly to plastic containers for holding carbonated or like products that expand after sealing or capping.
Plastic bottles are in widespread use for containing beverages and food products. A particular type of bottle, which is filled with products at elevated temperatures, is designed to accommodate internal vacuum pressure developed upon cooling of the products after sealing. Often, hot fill bottles include panels formed in the container sidewall that inwardly flex or deform in response to formation of an internal vacuum. For example, U.S. Provisional Patent Application No. 60/295,911, filed Jun. 4, 2001, entitled “Hot-Fillable Container With Grip” discloses a bottle in which inward, vacuum-induced deformation is distributed outside of the handgrip panel.
Another type of plastic bottle that contains carbonated beverages (or like products that exhibit increased internal bottle pressure—that is, compared with the internal pressure upon or soon after capping or sealing) is designed to accommodate internal positive pressure (that is, pressure greater than the ambient atmosphere). Such bottles, which will be referred to herein as “pressurized bottles,” are typically formed of blow-molded PET that is capable, upon orienting, of containing an internal bottle pressure of several atmospheres, which may occur when carbonated contents within a bottle are exposed to elevated temperatures, such as 100 degrees F. to 120 degrees F. Such temperatures may be encountered during storage or during transport while the bottle is not in an air-conditioned environment, or like circumstances.
Plastic bottle production is, of course, a competitive industry in which weight-reducing techniques produce significant costs savings, especially in light of the vast quantity of bottles produced worldwide. However, the high internal pressures that pressurized bottles must contain provides a constraint against bottle weight reduction.
U.S. Pat. No. 6,176,382, entitled “Plastic Container Having Base with Annular Wall and Method of Making the Same,” discloses a conventional beer bottle shape that may be subject to high internal pressures due to the carbonated (or otherwise pressurized, such as for example by nitrogen) beverage contained therein being exposed to elevated temperature. In this regard, as in most conventional beer bottles and many other pressurized bottles, the exemplary bottle
110
shown in
FIG. 7
(PRIOR ART) has a tapered neck
112
extending above a right circular body
116
. A shoulder
118
is disposed between neck
112
and body
116
. A label panel
120
is defined by at least a portion of body
116
. Neck
112
may also receive a label (not shown in the Figures).
Neck
112
has a continuous taper so as to form a frustum of a right circular cone. In this regard, a neck diameter D-PA
1
near an upper end of neck
12
is less than a diameter D-PA
2
near a lower end of neck
12
. Another conventional glass bottle shape (not shown in the Figures) has an upper neck diameter that is the same as the lower neck diameter such that the neck substantially forms a cylinder having a circular cross section. In this regard, the term “straight” or “straight portion” will be employed to refer to a sidewall or a sidewall portion, respectively, that is rectilinear or not curved in longitudinal cross section.
Referring again to
FIG. 7
, the straight sidewalls of neck
112
and body
116
deform in response to an increase in internal pressure, as indicated diagrammatically by the dashed lines in FIG.
7
. The maximum radial expansion is indicated by &Dgr;-PA-neck and &Dgr;-PA-body, respectively. Typically, the volumetric expansion of the neck is less than the volumetric expansion of the body and/or the base.
Often, a plastic bottle is developed to replace a corresponding glass container with economic advantages that are apparent. In some circumstances, technical problems must be solved to make a plastic bottle that is commercially satisfactory. For example, a plastic bottle containing a carbonated (or otherwise pressurized) product inherently yields more than a corresponding glass container in response to an increase in internal pressure. Thus, a label panel of a plastic pressurized bottle may deform in response to an increase in internal pressure. Such label panel expansion is undesirable for aesthetic reasons and because the label may tend to separate from the label panel. Further, the bottle base may tend to bulge or “roll out” in response to such internal pressure, thereby making the base unstable.
In order to produce a bottle that is sufficiently strong to withstand such internal pressure without unacceptable label expansion and/or base expansion or roll-out, bottles formed of oriented thermoplastic are designed with a sidewall and base of sufficient thickness and weight. In general, there is a need for pressurized bottles that have improved expansion characteristics, and/or reduced weight.
SUMMARY
A bottle is provided that includes a neck that expands volumetrically in response to an increase in internal bottle pressure. In this regard, such a plastic container comprises a body, a base extending from the body and enclosing a lower end of the container, a finish disposed at an upper end of the container, and a neck disposed between the finish and the body. The neck includes an outwardly convex portion that radially expands in response to positive internal pressure, whereby the maximum magnitude of the radial expansion is less than a maximum magnitude of radial expansion for a frusto-conical neck of like dimension.
Further, the bottle may include a waist that is outwardly concave such that the convex portion of the neck extends upwardly from and smoothly yields from the waist. Thus, the waist may form a hinge point relative to the convex portion. According to another aspect, the neck's convex portion expansion may diminish expansion of the body straight sidewall, thereby enhancing the appearance and adherence of the label. Also, such expansion may enable the total weight of the bottle to be reduced.


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patent: 6257433 (2001-07-01), Ogg et al.
patent: 2414945 (1975-10-01), None
U.S. patent application Publication No. 2002/0070193 A1 to MERO, Published Jun. 12, 2002.

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