US3507440A

US3507440A - Top-opening carton

Info

Publication number: US3507440A
Application number: US716755A
Authority: US
Inventors: Robert O Stuberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-03-28
Filing date: 1968-03-28
Publication date: 1970-04-21
Anticipated expiration: 1987-04-21

Description

April 21, 1970 R. o. STUBERG TOP-OPENING CARTON Filed March 28, 1968 FlG 1 INVENTOR. ROBERT O. STUBERG BY 7mm FlG 4 ATTORNEYS United States Patent 3,507,440 TOP-OPENING CARTON Robert O. Stuberg, 101 Bella Vista Drive, Hillsborough, Calif. 94010 Filed Mar. 28, 1968, Ser. No. 716,755 Int. Cl. B65d /02, 5

US. Cl. 229-33 5 Claims ABSTRACT OF THE DISCLOSURE A top-opening carton for minimizing moisture/vapor loss from frozen comestibles within the carton through the use of a front flap corresponding in shape to a cutaway segment of the respective wall panel. When the flap is tucked inside this cutaway segment of the wall panel and pressure employed to accomplish sealing (either by gluing or by softening a thermoplastic coating), the resiliency of the paperboard proximate the score line of the flap and the back-up support created by the top panel provide resistance in opposition to the applied pressure so that a continuous seal is formed across the front of the carton, using a minimum or much smaller blank than normally required.

This invention is directed to a top-opening carton. More particularly, the invention is directed to a topopening carton suitable for minimizing moisture and vapor loss during storage of packaged products.

Present commercially available top-opening (topclosing) carton-s utilize a lid hingedly secured along one edge thereof to one side wall panel of a rectangularlyshaped body. Flaps extend outwardly from the other three edges of the lid to provide an overlap with the respective wall panels of the body. In operation the body is filled with the particular material being packaged and the lid positioned to cover the body opening. Then the overlapping flaps are adhered (or locked by means of male and female locking cuts and tabs) to respective wall panels to retain the lid member as a closure for the opening in the body. The method for adhering the flaps to the Walls of the body conventionally involves, for example, applying glue and pressure for attachment or by locking of the flaps to the outside of the wall panels. Alternately, where the carton blank is formed with a thermoplastic surface coating, appropriate portions of the coating are first softened and thereafter the flaps are maintained in contiguous association with respective of the wall panels of the body while the tacky thermoplastic coating is allowed to cool and solidify. The adherence is normally accomplished along the lower portion of the respective wall panel where the bottom panel provides the necessary back-up pressure. In this manner, the flaps are secured to the body, thereby providing an integral enclosure, until the carton contents are to be utilized.

Although this type of carton is quite satisfactory when it is employed in conjunction with a tightly-sealed moisture/vapor impervious overwrap or when the comestible is initially packaged in a heat-sealed plastic bag and the bag inserted in the carton, this conventional carton in and of itself does not provide the degree of moisture/ vapor retention necessary to prevent product degradation or even minimize the rate thereof irrespective of the adhering technique employed. The oppositely-disposed flaps can be subjected to sufficient pressure during the adhering procedure to provide a bond exhibiting satisfactory moisture/vapor characteristics, but the flap overlapping the front wall panel cannot be sealed as effectively. Further-more, as the front overfiap is reduced in width, less resistance is provided by the front panel. Al-

3,507,440 Patented Apr. 21, 1970 through the front panel may be rigid along the score lines forming its side edges and lower edge (where back pressure is provided by the adjoining perpendicular panel), the internal area of the wall panel is quite flexible. Thus, the upper portion thereof provides insufiicient resistance or back pressure in opposition to the force applied for accomplishing physical contact between the overlapping flap and the front wall panel. As a result, the desired adherence is not obtained. In other words, with present carton structures, sufficient pressure cannot be applied along the overlap front flap and against the whole front wall panel to create uniform contact and adherence. Thus, the continuity of seal necessary to form an adequate moisture/vapor barrier along the front of the carton is not provided.

It is the principal object of this invention to provide a carton closure that produces a good bond using glue or thermoplastic coatings.

It is a further object of this invention to eliminate the need for a moisture/vapor impervious overwrap or an inner heat-sealed plastic bag (innerwrap) in frozen food consumer packages.

It is another object of this invention to provide an open-topped carton that can be effectively sealed at speeds currently employed in assembling lock or glue style closures.

It is still another object of this invention to provide an open-topped frozen food carton that can be conveniently heat sealed.

It is a further object of this invention to provide a top-opening frozen food carton from a single sheet blank. t

It is a feature and advantage of this invention to utilize a flap that tucks within the upper portion of the frontal wall panel of top-opening carton so that when pressure is applied against the upper portion of the frontal wall panel, the pressure will be resisted by both the natural resiliency of the flap to-spring back about the score line between the flap and the lid, and the edge rigidity of the top panel.

These objects, features and advantages will be better understood and others will become apparent when reference is made to the following detailed disclosure especially in view of the attached drawing wherein:

FIG. 1 is a perspective view of a carton blank showing one embodiment incorporating the features of this invention; and

FIGS. 2, 3 and 4 are partially cutaway perspective views illsutrating the sequential steps involved in obtaining the finished carton of this invention from the embodiment of FIG. 1.

Referring more particularly to the drawing, wherein similar characters of reference represent corresponding parts in each of the several views, in FIG. 1 there is shown a carton blank A that has been formed from a flat sheet of flexible material in a conventional manner such as with rotary blank-forming (or die-cut forming) paperboard manufacturing equipment.

Blank A includes a number of longitudinal score lines 10 and a number of transverse score lines 12 disposed to form bottom panel 14, top panel 16 and

side panels

18, 20, 22 and 24.

Flaps

26, 28 and 30 are hingedly attached to top panel 16 along respective of

score lines

10 and 12.

Side panels

18 and 22 are also provided with

flaps

32, 32', 32" and 32", extending from respective of their edges for attachment to respective portions of

side panels

20 and 24, such as by gluing, to form a rectangular body from blank A. It will be apparent to one skilled in the art that gluing is merely one of a number of methods of interconnecting the various side walls to provide a rectangular body for the carton. The body of the carton may also be formed by interlocking tongues and slits as well as by heat sealing the flaps to the side panels.

Turning more specifically to side panel 22, it includes a score line 36 intermediate the height of panel 22 and extending for a substantial part of the length thereof. Slits 38 and 38 extend from respective ends of score line 36 out to the outer edge of panel 22. Slits 38 and 38', score line 36, and the outer elongated edge of side panel 22 define an upper segment (portion) 40. Extension 28 is formed with an outer edge 42 and

side edges

44 and 44 to provide a flap corresponding in configuration to upper segment 40 of panel 22. In this manner, after extension 28 is inserted within the body of the carton formed by blank A, upper segment 40 can be bent away for inserting glue or for heating a thermoplastic coating on the outer surface of extension 28 and the inner surface of segment 40. In another aspect, it is advantageous for both flap 28 and upper segment 40 to be of trapezoidal configuration so that segment 40 can also be moved out of the plane of side panel 22, if desired, to allow for insertion of flap 28 within the body of the carton.

Referring now to FIGS. 2-4 depicting the assemblage of carton B, body portion including bottom panel 14 and

side wall panels

18, 20, 22 and 24 are assembled in a conventional manner. Thereafter,

fiaps

26 and 30 are secured to respective of

side walls

24 and 20. Upper portion 40 is then moved out of the plane of wall panel 22 to provide a path of ingress for flap 28 as shown most clearly in FIG. 2. Referring to FIG. 3, fiap 28 is inserted entirely within the plane of panel 22. Upper segment 40 is then attached to panel 28 to provide the final structure as shown in FIG. 4. A heated die is inserted between the inner surface of upper segment 40 and the outer sur face of flap 28 to elevate the temperature of the thermoplastic coating so that it will become tacky. Thereafter, pressure is applied against the outside surface of upper segment 40 so that the inside thereof is forced into intimate contact with the outer surface of flap 28. Flap 28, because of the resiliency of the flexible material comprising blank A, tends to spring outwardly around score line 12 towards its original fiat position. In this manner, flap 28 will push back against the force being applied to upper portion 40 and provide the continuity of contact required to obtain an adequate seal. It will be apparent to one skilled in this art that as the width of flap 28 increases, the resiliency of the flap will diminish. Thus, it is preferable to form flap 28 with as small a width as possible. In this manner, optimum advantage is also obtained from back-up support provided by top panel 16. In this regard, it has been found most advantageous to utilize a flap 28 having a Width no greater than half the height of panel 22 and preferably of from about /2 inch to /8 inch wide.

In a preferred embodiment, and as shown most clearly in FIG. 3, it is desirable that flap 28 have a slightly larger cross-sectional area than upper portion 40. In this manner, when segment 40 is sealed against fiap 28, the surface of flap 28 will overlap

slits

38 and 38 and ensure a more effective moisture-vapor barrier.

The thermoplastic surface coating employed in this in vention can be any of those presently commercially available to the packaging industry including polymers of polyethylene and the like. Such coating materials are suitable for direct on-carton printing and are especially advantageous in this invention where the need for a printed overwrap is diminished.

Although the foregoing invention has been described in some detail by way of illustration for purposes of clarity of understanding, it will be apparent to one skilled in this art that certain changes and modifications may be practiced within the spirit of this invention.

What is claimed is:

1. A top-closing carton comprising: an open-topped body having a height defined by four interconnected side walls; a lid having a first edge thereof hingedly secured to the upper edge of one of said sidewalls and movable into covering relationship with the open top of said body, said lid including a pair of flaps hingedly secured to second and third edges thereof, a sidewall other than said one side wall having a score line extending along a portion of its length intermediate its height, said other sidewall being further provided with a pair of slits extending inwardly from the upper corners thereof to respective ends of said score line, to define a trapezoidal segment with the upper portion of said other sidewall; said lid having a trapezoidal-shaped extension hingedly secured along a score line to the fourth edge of said lid, said extension defining a width greater than the height of said trapezoidal segment and being movable into said body; and means for adhering the outside of said extension to the inside of said segment; whereby when said extension is adhered to said segment, said extension will cover said slits to minimize moisture-vapor loss from within said carton.

2. A top-opening carton in accordance with claim l and further characterized by means for adhering the inside of said pair of flaps to the outside of respective of said side walls.

3. A top-opening carton in accordance with claim 2 wherein said adhering means is by a thermoplastic coating that becomes tacky when subjected to sufficient heat.

4. A blank for forming a top-closing carton suitable for minimizing moisture-vapor loss from within said carton, comprising: a substantially flat, vapor-impervious sheet cut and scored to provide a series of wall panels hingedly connected to a bottom panel and adapted to be interconnected to each other, one of said wall panels also being hingedly connected to one edge of top panel corresponding in configuration to said bottom panel; a wall panel other than the wall panel hingedly connected to the top panel including a moisture-vapor impervious score line along a portion of its length to define a line intermediate to its Width, said other Wall panel being further provided with a pair of slits extending inwardly from the upper corners thereof to respective ends of said score line, to define a trapezoidal segment within the upper portion of said wall panel; flaps hingedly attached to each of the other three edges of said top panel, two of said fiaps being of a size sufficient to overlap respective of said wall panels, the remaining flap being of a trapezoidal cross-section for overlaying said other wall panel, said remaining flap defining a width greater than the height of said trapezoidal segment and being movable into said body so as to abut said segment; and means for adhering opposite of said two flaps to the outside of respective of said wall panels and said remaining flap to the inside of said opposite wall panel at said trapezoidal segment.

5. A blank in accordance with claim 4 wherein said adhering means comprises a thermoplastic coating.

References Cited UNITED STATES PATENTS 1,992,222 2/1935 La Grua 2295l 2,038,893 4/1936 Davidson 22951 2,104,195 1/1938 Groeling 229-33 2,122,885 7/1938 Lowey 229-5l X 2,828,060 3/1958 Brown 229-51 X 3,306,517 2/ 1967 Diesinger 2 2 9-37 DAVIS T. MOORHEAD, Primary Examiner U.S. Cl. X.R. 22937, 51