Plastic jar

A lightweight plastic jar having outwardly convex front end and back walls, each having a relatively large radius of curvature, and a pair of side walls having relatively large planar portions capable of controlled inward deflection to accommodate decreases in the interior volume of the jar. The jar is configured to facilitate dispensing of product while also providing strength, efficient use of space in packing with like containers, and an attractive appearance.

BACKGROUND OF THE INVENTION 
The invention relates generally to plastic containers, and more 
specifically to molded polymeric bottles or jars. 
In providing a container for commercial packaging of food products, among 
the considerations that must be addressed are the ability of the container 
to receive product in filling operations; the degree of difficulty that 
will be encountered by the consumer in dispensing product from the 
container; the ability of the container to withstand various loads, such 
as stacking loads, during filling, sealing, shipping, display and consumer 
use; the ability of the container to be packed efficiently among like 
containers; and the appearance of the container. 
Plastic bottles and jars are widely used for food products, and provide 
lightweight, relatively inexpensive packaging. One disadvantage of many 
plastic containers is that they are subject to panelling, i.e., localized 
inward deflections or dents which significantly distort portions of the 
container. Panelling occurs as a result of pressure in the sealed interior 
of the container dropping below atmospheric pressure. Such a pressure drop 
may be caused by cooling of the product after filling or by other factors. 
Panelling is undesirable not only due to the fact that it may reduce the 
container's ability to stably withstand compressive vertical loading when 
upright, but also due to its negative aesthetic impact, making the 
container appear damaged or deformed and therefore possibly unacceptable 
to the consumer. 
A general object of the invention is the provision of a lightweight, 
economical plastic jar which is capable of responding to interior pressure 
reductions without panelling. Further objects and advantages of the 
invention are set forth below. 
SUMMARY OF THE INVENTION 
In accordance with the invention, there is provided a lightweight plastic 
jar having outwardly convex front and back walls, each having a relatively 
large radius of curvature, and a pair of side walls having relatively 
large planar portions capable of controlled inward deflection to 
accommodate decreases in the interior volume of the jar. The curved front 
and back walls are also capable of slight inward deflection while 
maintaining their outward convexity. 
In accordance with a further feature of the invention, the configuration of 
the jar, and particularly the shoulder area, facilitate dispensing of 
product while providing sufficient strength and rigidity. To this end, the 
shoulder surfaces slope steeply downward from a relatively large mouth to 
corners which preferably have radii of curvature of at least about 0.5 in.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
The invention is generally embodied in a molded polymeric container or jar 
10. In the illustrated embodiment, the jar 10 has a generally rectangular 
configuration as viewed in plan, comprising upstanding, outwardly convex 
front and back walls 12 and 14, and upstanding side walls 16. The jar has 
a base 28 which includes a generally horizontal bottom wall 18 and at its 
upper end has an annular mouth 20 with means thereon for cooperating with 
a closure 22 to seal the container. A shoulder area 24 slopes downward 
from the mouth 20 of the container to the upstanding walls. 
In accordance with a feature of the invention, to enable the container to 
decrease in interior volume in response to decreased internal pressure, 
each of the side walls 16 has an inwardly displaceable portion 26 disposed 
generally centrally thereof. In the illustrated embodiment, the inwardly 
displaceable portions are relatively large, substantially planar areas. 
The remaining surface area of the container is in major part outwardly 
convex and derives somewhat greater rigidity from its configuration. 
The base portion 28 comprises four upstanding wall portions 30, 31, 32 and 
33 which are outwardly convex as viewed in elevation (See FIGS. 2 and 3), 
with a radius of curvature of about 1.5 to 2 in. as viewed in elevation. 
The wall portions 30 and 32 at the lower ends of the front and rear walls 
12 and 14 are also outwardly convex as viewed in plan, having a radius of 
curvature as viewed in plan corresponding to that of the front and rear 
walls. The base wall portions 30, 31, 32 and 33 intersect the bottom wall 
18 at a smaller radius of curvature. At the intersection of the base 28 
and the upstanding walls is an inflection line 34, which extends about the 
container. 
The lower portion 42 of the shoulder area 24 is also outwardly convex as 
viewed in elevation on all four sides. In accordance with a feature of the 
invention, to facilitate dispensing of product from the jar while 
providing structural rigidity, the lower portion of the shoulder area has 
a radius of curvature of about 0.75 to 1 in. as viewed in elevation, and 
is also outwardly convex as viewed in plan along its forward and rear 
surfaces with curvature corresponding to that of the front and back walls 
12 and 14. An inflection line 36 extends along the intersection of the 
shoulder area 24 with the upstanding walls 12, 14 and 16. 
Each of the inwardly displaceable, substantially planar portions 26 is 
slightly recessed and surrounded by an integral frame 38 which is itself 
surrounded by a peripheral area 40 of the side wall 16. The displaceable 
portions 26 are generally rectangular with rounded corners, and have 
sufficient area that slight inward deflection is sufficient to accommodate 
normal interior volume changes and avoid panelling. .Due to the location 
and configuration of these portions, normal inward deflection or 
distortion thereof does not significantly detract from the strength or the 
appearance of the container 10. A pressure differential across the side 
wall 16 due to a pressure drop in the interior of the jar 10 deflects the 
side wall 16 inward, with the center of the planar portion 26 undergoing 
maximum displacement, and the peripheral area 40 bending slightly inward 
as well. 
The provision of the aforedescribed structure enables the container 10 to 
accommodate decreased interior pressure without inward buckling or 
panelling of the front and back walls 12 and 14. It may be noted that the 
range of motion of the side walls is necessarily limited in the 
illustrated embodiment, and that in the event of a very large decrease in 
interior volume, buckling of one or both of the front and back walls may 
be unavoidable. However, the side walls can be configured to accommodate 
volume changes occurring under normal conditions for particular products. 
The illustrated jar is intended to be used as a container for 48 oz. 
quantities of mayonnaise, packaged for consumer sale. 
The upper portion of the shoulder area slopes downward from the mouth 20 of 
the jar 10. The slope is somewhat greater at the front and back than at 
the sides, due to the width of the jar being greater than its depth. All 
portions of the shoulder area have a slope of at least about 45.degree. 
and the front and back portions slope at about 65.degree.-70.degree.. The 
mouth in the illustrated embodiment has an inner diameter of about 3 in. 
and a height of about 0.75 in. to 1 in., and has an exterior thread 44 for 
engagement with a corresponding interior thread on a cooperating lid 22. 
The combination of the relatively wide mouth and sloped shoulders 
contributes to the facility of product dispensing. 
The jar 10 is preferably made of a suitable polymeric material such as 
polyester, and is preferably transparent. The illustrated jar has a height 
of about 7 in.; width of about 4.5 in.; and depth of about 4 in. The 
vertical dimension between the inflection lines 34 and 36 is about 4 in. 
The planar areas 26 measure about 3.5 in. by 1.5 in., and are indented 
from the surrounding areas of the respective side wall by about 0.1 in. in 
their undisplaced positions. Each of the front and back walls is 
preferably vertical and shaped as a portion of a cylinder, having a radius 
of curvature of about 4 in. As viewed in plan, the radius of curvature at 
each of the four corners is about 0.5 in. to 0.75 in. 
From the foregoing it should be appreciated that the invention provides an 
improved container capable of withstanding controlled inward deformation 
due to interior pressure drops without undesirable panelling. The 
configuration of the container further provides advantages in facilitating 
dispensing of products such as mayonnaise. The jar enables relatively 
efficient use of space in transportation and display, in that it interfits 
with like jars with relatively little interstitial space as compared with 
round jars. Also, the illustrated 48 oz. jar fits in standard refrigerator 
door shelves which will not accommodate 48 oz. round jars presently in 
use. The jar further compares favorably with conventional glass jars with 
respect to impact resistance. 
The invention is not limited to the embodiment described above or to any 
particular embodiment, but is pointed out by the following claims.