CA1071155B - Egg carton - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to a foamed thermoplastic packaging structure designed to package eggs and the like.
The package includes a body section and the body has a plurality of downwardly directed deep egg receiving pockets. All adjacent pockets are separated by at least one flexible thin-walled separator which prevents substantial contact and which provides resilience and flexibility between the eggs positioned in the pocket. The separator is formed by upwardly directed extension walls formed continuously with and extending upwardly from the pocket walls of the adjacent pockets. Each of the extension walls terminates in individual upper end walls, and the walls of the pockets have individual relatively thick cross-sections of from 30 to 120 mils to provide structural strength in the structure. The walls of the separator have individual relatively thin cross-sections of at least 5 mils to prevent substantial contact and to provide resilience and flexibility between the eggs in the pockets. In accordance with the invention, the ratio of cross-sectional width of the thick walls to the cross-sectional width of the thin walls is from 1.2 to 24.

Description

1071~5~
This invention relates to improvements in cartons manufactured for packaging, shipping, storing and merchan-dising eggs or other fragile articles and, more particularly, to egg carton structures made from thermoplastic resinous materials such as foamed polystyrene and the like.
In general, eggs and like fragile articles are packed for shipment and merchandising in protective packages which usually have a dozen egg cells in two rows of six each for receiving the individual eggs. In the past, egg cartons were usually made from paperboard or a composition of molded wood pulp, but more recently egg cartons have been made of thermoplastic resinous materials such as foamed polystyrene.
Wood pulp and thermoplastic foams generally provide materials of acceptable softeness and resilience to protect fragile articles such as eggs, but the requisite carton strength and cell capacity have been achieved through the use of special structural design components.
Previously, a primary problem has been the incor-poration of a soft resilient material into egg cartons which will also provide sufficient isolation and rigidity to pre-vent eggs from contacting each other and breaking during rough packaging, handling and shipping of the same. The problem of providing sufficient isolation and rigidity in egg cartons has resulted in a variety of designs including reinforcing ribs, and walls or other transverse stiffening means to overcome the economic disadvantage of suing an excess of structural material. In addition, a variety of upwardly extending dividers or separators disposed between the egg receiving cells have been used to isolate one egg from another. Egg cartons illustrating the use of both . .

transverse stiffening means and cell separators are found in U.. Patents 3,563,446 issued on February 16, 1971 to Patentee Connie Lake and Nickolas D. Commisso and 3,375,966 issued on April 2, 1968 to Patentee Kenneth L. Crabtree.
Although the use of known transverse stiffening means and separators have overcome many problems involving egg packaging, their use has created an additional problem.
It has been found that it is difficult, if not impossible, to satisfactorily form foam plastic cartons with such fea-tures because of the deep draw of material required to formthe transverse stiffening means and separators together. It is not practical to overcome this problem by using an excess of structural material because such makes the cartons more expensive to produce as compared to other egg carton designs.
In general, the present invention provides an egg carton useful in packaging and handling of eggs or other fragile articles. The unitary structure of the egg carton is preferably formed from thermoplastic material such as polystyrene foam sheet. Although other materials such as -molded pulp can be used to make the egg cartons, thermo-plastic foam material, is preferred because the egg carton designs overcomes a critical carton forming problem which makes such foam material more competitive with other struc-tural materials.
In the present invention, it has been found that a variable thickness of cell and separator walls, in con-~unctlon with other unique elements or features, results in a structure which does not require extensive lateral or trans-verse ribs and walls or other means to provide satisfactory lateral support between cells or general stiffness reinforce-ment of egg cartons as prviously considered necessary. A

functional egg carton having satisfactory overall strength ~071155 is produced by maintaining a relatively thick cross-section in the cell, cover and peripheral walls, and a relatively thin cross-section in large flexible separators between the cells. By eliminating the need for extensive transverse stiffening means, a thermoplastic foam egg carton can be formed by vacuum forming, matched mold or other known tech-niques without resortint to excessive structural material to-prevent tearing or other failure of such foam material due to excessive drawing of the foam material during the forming operation.
The present invention comprehends an egg carton comprising a bottom section having a plurality of downwardly directed deep egg receiving pockets or cells. If the poc-kets or cells are disposed in adjacent rows, the cell walls of four adjacent cells, two adjacent cells located in each of two adjacent rows, converge and interconnect into an inter-mediate horizontal transverse wall which is generally cen-trally and symmetrically located with respect to said cells.
In accordance with the invention, adjacent egg cells, in any arrangement of cells or pockets, whether in rows or not, are separated by at least one large flexible thin-walled separator or divider. The separators are up-wardly directed extensions of the cell walls of the adjacent cells. The separators are large and sufficiently thin walled toprevent contact and provide flexibility and resilience be-tween eggs in adjacent cells. A closable cover and means to maintain said cover closed are interconnected with the bottom section. The type of cover and locking means which can be used is illustrated by U.S. Patent 3,326,443 issued on June 20, 1967 to Patentee Francis L. Burkett.
Particular novel features of the invention des-cribed above reside in cells, peripheral walls and a 1~)7~155 closable cover and locking means with a relatively thick cross-section sufficient to provide satisfactory structural strength and large, thin-walled flexible separators which prevent contact and provide resilience and flexibili-ty between eggs of varying dimensions in adjacent cells. If the above features of the present invention are used in combination, an egg carton formed from thermoplastic foam sheet which does not have or need extensive transverse stiffening elements, or necessitate deep drawing in its formation can be made that will be competitive with egg cartons made from other competitive egg carton materials.
Accordingly, the present invention provides a foamed thermoplastic packaging structure designed to package eggs and the like which comprises a body section including a plurality of downwardly directed deep egg receiving pockets, all adjacent pockets separated by at least one flexible thin-walled separator means preventing substantial contact and providing resilience and flex-ibility between said eggs and the like positioned in said pockets, said separator means formed by upwardly directed extension walls formed continuously with and extending upwardly from said pocket walls of said adjacent pockets, each of said extension walls terminating in individual upper end walls, the walls of said pockets having individual relatively thick cross-sections of from 30 to 120 mils to provide structural strength in said structure and the walls of said separator means having individual relativelv thin cross-sections of at least 5 mils to prevent substan-tial contact and provide resilience and flexibility between said eggs and the like in said pockets, and further ~ _ 4 _ characterized in that the ratio of cross-sectional width of the thick walls to the cross-sectional width of the thin walls is from 1.2 to 24.
The present invention is illustrated in the accompanying drawings in which like characters of refer-ence designated corresponding material and parts -through-out the several views thereof, in which:
Figure 1 is a plan view of an egg carton embodying the features of the invention;
Figure 2 is a vertical section taken along - refernce line 2-2 of Figure l;
Figure 3 is a partial vertical section taken along reference line 3-3 of Figure l;
Figure 4 is a partial vertical section taken along reference line 4-4 of Figure l;
Figure 5 is a partial vertical section taken along reference line 5-5 of Figure l; and Figure 6 is a magnified partial vertical sec-tion taken along reference line 6-6 of Figure 1, illus-trating the thin and flexible walls of the side andcenter separators.
The following description illustrates the manner in which the principles of the invention are applied.

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More specifically, the egg carton of this embodi-ment is formed from a sheet of thermoplast:ic polystryrene foam and is generally mass produced on a thermoforming machine from a foam sheet. As an example, such sheet can have a thickness of from about 50 to 200 mils. The egg carton produced can weigh, depending on its particular size and shape, from about 10 to 25 grams, preferably from 15 to 20 grams, and can vary from being no thicker than about 5 to 25 mils in cross-sectional wall thickness for the relative-ly thin separators and from about 30 to 120 mils cross-sectional wall thickness for the relatively thicker cells, peripheral walls, and closable cover and locking means The egg carton to be presently described in detail is that of the type conventionally described as a 2 x 6 one dozen egg carton, i.e., holds 12 eggs in two adjacent rows of six each. However, the principles o~ the present inven-tion can likewise be applied to other sizes of cartons and carton shapes, such as the 3 x 4 cartons also well known in the industry, or in larger filler flats, for example. Inas-much as the cells and oher cooperating portions of the eggcarton are substantially uniform throughout the same, only one of each of the cooperating elements will be described in detail.
The egg carton is indicated generally at 10 in Figures 1 and 2, and comprises a unitary structure having a bottom section 12, a closable cover 14 and locking member 16. s previously, noted, the structure of the closable cover 14 and locking member 16 are best illustrated in U.S.
Patent 3,326,443.

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The bottom section 12 includes an outer periph-eral wall 18 and a plurality of cells indicated generally at 20 produced in two rows of six each. The cell walls 21 of four adjacent cells 20, two adjacent cells located in each of the two adjacent rows, converge and interconnect with intermediate horizontal transverse walls 22. In addition, two adjacent cells 20, in the rows and across adjacent rows, are separated by flexible thin walled side and center separators indicated generally at 24 and 26, respectively. The side separators 24 and center separators 26 are formed by extension walls 34 of walls 21 of cells 20 and terminate at upper end walls 28 and 30, respectively.
Side walls 32 interconnect the upper end walls 28 and 30 with transverse walls 22, and the outer part of upper and walls 28 merges with outer peripheral wall 18 to complete the formation of the side separators 24 and center separators 26.
As previously noted, a particularly novel feature of the present invention resides in varying the cross-section-al wall thickness of the different elements in the eggcarton 10. By having thick walled cross-sections in cells 20, peripheral wall 18, cover 14 and locking member 16 to provide egg carton 10 with structural strength and by having thin walled cross-sections in the side separators 24 and center separators 26 to provide resilience and flexibility between eggs positioned in cells 20, it is possible to eliminate unnecessary transverse reinforcement means which creates problems during forming of egg cartons from thermo-plastic foam sheets. Figure 6 is a fragmented magnified view illustrating this difference in relative thickness 1~)7~55 between the extension walls 34 of the side and center separators, 24 and 26 and walls 21 of cells 20.

Claims (5)

1. A foamed thermoplastic packaging structure designed to package eggs and the like which comprises a body section including a plurality of downwardly directed deep egg receiving pockets, all adjacent pockets separated by at least one flexible thin-walled separator means preventing substantial contact and providing resilience and flexibility between said eggs and the like positioned in said pockets, said separator means formed by upwardly directed extension walls formed continuously with and extending upwardly from said pocket walls of said adjacent pockets, each of said extension walls terminating in individual upper end walls, the walls of said pockets having individual relatively thick cross-sections of from 30 to 120 mils to provide structural strength in said structure and the walls of said separator means having individual relatively thin cross-sections of at least 5 mils to prevent substantial contact and provide resilience and flexibility between said eggs and the like in said pockets, and further characterized in that the ratio of cross-sectional width of the thick walls to the cross--sectional width of the thin walls is from 1.2 to 24.

2. The packaging structure of Claim 1 wherein said cells or pockets are disposed in adjacent rows and four adjacent cells or pockets formed by two adjacent cells or pockets located in each of two adjacent rows are inter-connected with intermediate horizontal transverse walls which are centrally and symmetrically located with respect to said four adjacent cells or pockets, said transverse walls having relatively thick cross-sections of from about 30 to 120 mils to provide structural strength in said structure.

3. The packaging structure of Claim 1 wherein said thermoplastic foam is polystyrene foam sheet.

4. The packaging structure of Claim 1 wherein said structure is a carton including a closable cover and a means to maintain said cover closed, said cover and means to maintain said cover closed having relatively thick cross--sections to provide structural strength in said carton.

5. The packaging structure of Claim 1 wherein said structure is a filler flat adapted to be positioned one on top of the other in a container.