In-Folded Fin Seal End Closure

This invention relates generally to liquid-carrying, thermoplastic coated paperboard cartons and, more particularly, to a flat end closure therefor.

Heretofore, thermoplastic coated paperboard cartons having flat end closures of the in-folded and/or out-folded fin sealed types formed on opposite ends thereof have been used with generally satisfactory results. However, when the, so-called, in-folded type of end closure is used, several panel thicknesses are operative in the folding operations, the panel thicknesses result in crowding of layers, causing stretching or tensioning of the outermost layers around inner layers to the extent that some outermost layers tend to pull apart and crack, thereby destroying the liquid impermeable thermoplastic layer, producing bulging of the paperboard and subsequent leaking therethrough.

Accordingly, a general object of the invention is to provide an improved in-folded fin sealed type of end closure for a thermoplastic coated paperboard carton, with provisions for retarding inherent characteristics tending to cause cracking of the thermoplastic coating during the forming operations.

Another object of the invention is to provide an improved in-folded fin sealed type of end closure for a thermoplastic coated paperboard carton, including supplementary sets of score lines for facilitating folding without causing tensioning and cracking of edges of the various layers during the folding process.

A further object of the invention is to provide an in-folded fin sealed type of end closure for a thermoplastic coated paperboard carton, including supplementary score lines which serve to convert 180.degree. end closure bends into two substantially 90.degree. bends, to thereby eliminate stretching or tensioning at the 180.degree. bend and resultant cracking of the thermoplastic coating.

Still another object of the invention is to provide an in-folded fin sealed type of end closure for a thermoplastic coated paperboard carton, including skewed supplementary score lines adapted to fold into position just inside the usual horizontal score lines separating the end closure panels from the sidewall panels, and providing a second bend for the paperboard layers in lieu of each usual 180.degree. bend about the horizontal score lines, thereby diminishing the chances for cracking of the thermoplastic coating at the bend locations.

These and other objects and advantages of the invention will be more apparent when reference is made to the following drawings and the accompanying description.

FIG. 1 is a fragmentary layout view of the outside surface of a thermoplastic coated paperboard container blank used to construct a container having an end closure in accordance with the present invention;

FIG. 2 is a fragmentary layout view of the outside surface of a container structure after it is side seamed from the container blank illustrated in FIG. 1;

FIG. 3 is a fragmentary perspective view showing the side seamed container blank illustrated in FIG. 2 in an open ended condition prior to the closing of the end closure structure of the present invention;

FIGS. 4 and 5 are fragmentary perspective views similar to FIG. 3, and showing the end closure evolved from the blank of FIG. 3 in partially closed conditions;

FIG. 6 is a fragmentary perspective view showing the container after the end closure has been bent and sealed into a flat, completely closed condition;

FIG. 7 is a fragmentary cross-sectional view taken along the plane of the line 7--7 of FIG. 6, and looking in the direction of the arrows, showing a prior art container after being folded through the steps of FIGS. 4, 5 and 6;

FIG. 8 is a fragmentary cross-sectional view taken along the plane of the line 8--8 of FIG. 6, and looking in the direction of the arrows, showing a container of the present invention after being folded through the steps of FIGS. 4, 5 and 6; and

FIG. 9 is a fragmentary layout view of the outside surface of an alternate embodiment of a thermoplastic coated paperboard container blank formed in accordance with the invention.

Referring now to the drawings in greater detail, FIG. 1 illustrates a fragmentary container blank 10 formed in accordance with the principles of the present invention. The container blank 10 is generally divided into three sections including a first end closure 12, a body portion 14, and a second end closure (not shown). A horizontal score line 16 extends transversely across the container blank 10 and separates the end closure 12 and the body portion 14. The body portion 14 comprises a plurality of integrally connected body panels, namely, a first panel 18, a second panel 20, a third panel 22 and a fourth panel 24, and a side seam flap or narrow fifth panel 26 formed adjacent the fourth panel 24. The container blank 10 is defined on its longitudinal sides by its free edges 28 and 30. The body panels 18, 20, 22 and 24, and the side seam flap 26, are defined by vertical score lines 32, 34, 36 and 38.

The end closure 12 has a pair of inner closure panels 40 and 42 which are integral with and extend longitudinally from the body panels 18 and 22, respectively. A pair of triangular closure panels 44 and 46 are an integral part of the end closure 12, and they extend longitudinally from the body panels 20 and 24, respectively. The triangular closure panel 44 is defined by the transverse score line 16 and diagonal score lines 48 and 50. The triangular closure panel 44 is integrally connected to the inner closure panels 40 and 42 by a pair of triangular panels 52 and 54, respectively. The triangular closure panel 46 is defined by the horizontal score line 16 and a pair of diagonal score lines 56 and 58. A pair of triangular panels 60 and 62 integrally connect the triangular closure panel 46 to the inner closure panel 42 and an extension 64 of the side seam flap 26, respectively. As is set forth in more detail hereinafter, the side seam flap 26 is connected to the inner closure panel 40 so as to place the triangular panel 62 adjacent the closure panel 40 in a constructed or erected container. Sealing panels 66, 68, 70, 72, 74, 76 and 78 are connected at a horizontal score line 80 extending transversely across the blank 10 to the panels 40, 52, 54, 42, 60, 62 and 64, respectively. A score line 69 separates the panels 68 and 70, and a score line 75 separates the panels 74 and 76.

Two sets of supplemental score lines 82, 84 and 86, 88 are formed adjacent opposite sides of the closure panels located intermediate the vertical score lines 32 and 34, respectively. Specifically, score line 82 is formed across the panel 40, beginning at the juncture of the score lines 16 and 32 and terminating at the score line 80 a predetermined distance from the vertical score line 32. The score line 84 is formed across the panel 66, beginning at the end of the score line 82 and angling toward the score line 32 to terminate at the free edge of the panel 66. The score lines 86 and 88 are the mirror image of the score lines 82 and 84 with respect to the vertical score line 34 on the panels 42 and 72, respectively.

Two more sets of supplemental score lines 90, 92 and 94, 96 are formed adjacent opposite sides of the closure panels located intermediate the vertical score lines 36 and 38, respectively. The set 90 and 92 is identical to the set 82 and 84, but with respect to the vertical score line 36 on the panels 42 and 72, and the set 94 and 96 is identical to the set 86 and 88, but with respect to the vertical score line 38 on the side seam panels 64 and 78. The extension of the free edge 28 is such that an inwardly tapered edge 98 borders the panel 40, and an outwardly tapered edge 100 borders the panel 66. The edges 98 and 100 are adapted to overlie the supplementary score lines 94 and 96, respectively, in the folding operation to follow.

The details of typical second end closure arrangements are discussed in detail in U.S. Pat. Nos. 3,498,524; 3,120,335 and 4,341,340.

The container blank 10 illustrated in FIG. 1 is first formed into a side seam blank as illustrated in FIG. 2. The side seam blank is formed by rotating the body panel 24 and the side seam flap 26 as a unit about the vertical score line 36, and having the inside surfaces of the body panel 24 come into contact with the inside surface of the body panel 22, with the vertical score line 38 positioned next to the vertical score line 34, and with the inside surface of the side seam flap 26 contacting the inside surface of the body panel 20 adjacent the vertical score line 34. The body panel 18 is then rotated about the vertical score line 32 to bring its inside surface into contact with the inside surface of the body panel 20. The inside surface of the body panel 18 along the edge 28 comes into contact with the outside surface of the side seam flap 26, and the edge 28 is positioned parallel and aligned with the vertical score line 38. The various members of the first end closure 12 and the second end closure (not shown) will make similar movements, and the container will appear as illustrated in FIG. 2. The container blank 10 is then sealed where the inside area of the body panel 18 comes into contact with the outside surface of the side seam flap 26.

The next step in forming the side seamed blank into a container is illustrated in FIG. 3. FIG. 3 illustrates how the side seam blank is opened up into a squared condition, after which the second end closure (not shown) is formed and sealed in a manner well known in the container art, and disclosed in detail in the above cited prior art patents.

After the second end closure (not shown) is formed and a product, such as milk or juice, has been inserted in the container, the various parts of the first end clousure 12 are folded about the various score lines in the following manner so as to form the closed end structure. The triangular panel 44 is moved around the horizontal score line 16 over the end of the filled container and away from its center. At the same time, the triangular closure panel 46 is likewise moved away from the center of the filled container about the horizontal score line 16. The inside surfaces of the sealing panels 68 and 70 are rotated towards each other about the vertical score line 69, the inside surfaces of the sealing panels 74 and 76 are rotated towards each other about the vertical score line 75, and the inside surfaces of the sealing panels 66 and 72 are moved toward each other. The inside surfaces of the triangular panels 52 and 54 thereby come into contact with the triangular panel 44, and the inside surfaces of the triangular panels 60 and 62 come into contact with the panel 46.

The sealing of the panels 70, 72 and 74 to the panels 68, 66 and 76, respectively, is accomplished by conventional means, such as a sonic or high frequency vibration sealing means, such a seal providing a liquid tight seal. The sealing of these various top end closure elements may also be accomplished by other means, such as gas heat, if desired.

FIG. 4 illustrates the positions of the various elements of the top end closure 12 once the sealing thereof has been effected and the top closure has been moved into a flat configuration with the 44 and 46 groups of panels extending outwardly from the side panels 20 and 24, respectively. As shown in FIG. 5, the 44 and 46 groups of panels are both folded inwardly with a 180.degree. turn about their respective segments of score line 16, into the flat configuration of FIG. 6.

Without the inclusion of the supplemental score line sets 82, 84; 86, 88; 90, 92; and 94, 96, the final folded configuration of FIG. 6 would include the seven thicknesses shown in FIG. 7, wherein three layers identified as 102 (including the panels 42 and 54), 104 (including the panels 72 and 70), and 106 (including the panels 66 and 68 each) will have been folded 180.degree. and one layer 108 (including the panels 20 and 44) will have been folded 90.degree.. Throughout such folding operations, at times the outermost 180.degree. folded layer 102 is stretched to the point where it becomes pulled apart at the score line 34, resulting in a crack, as shown at 110 in FIG. 7. Now, by including the supplementary score lines 82-96 and the edges 98 and 100, for the layers 102, 104 and 106 the severity of the bends for layers 102, 104 and 106 is reduced from 180.degree. bends to respective pairs of spaced apart substantially 90.degree. bends, as shown in FIG. 8. Specifically, there are panel portions between the various score lines at the corner shown in FIG. 8, i.e. a portion of the panel 42 between the score lines 86 and 34 where the latter separates the panels 54 and 42, a portion of the panel 72 between the score lines 88 and 34 where the latter separates the panels 72 and 70, and a portion of the panel 66 between the score lines 84 and 32 where the latter separates the panels 68 and 66.

Referring now to FIG. 9, an alternate blank embodiment 10' is shown, adaptable to being folded into a so-called, center side seam type of end closure. Those elements which differ from the respective elements of FIG. 1 are identified by reference numerals bearing primes; otherwise the elements are the same as those of FIG. 1.

Specifically, rather than a substantially full width panel segment 40 and a narrow side seam extension 64, the blank 10' includes two closure panels 40' and 64' and respective associated sealing panels 66' and 78', terminated by straight edges 28' and 30'. The associated body panels 18' and 26' are the same widths as the respective closure panels 40' and 64'.

While the folding process is the same as for the blank 10, once folded, the free edge 28' will be located at approximately the center of one of the sides of the resultant container, rather than at a corner, as in the case of the free edge 28 overlying the score line 38 shown in FIG. 3. In the folding process, the four sets of supplemental score lines 82, 84; 86, 88; 90, 92; and 94, 96 of the blank 10' function the same as those on the blank 10, resulting in an end closure like that shown in FIG. 8.

It should be apparent that the end closures formed from either the blank 10 or the blank 10' may be used for either a top or a bottom end closure, and that stretching and possible cracking resulting from 180.degree. bends (FIG. 7) is minimized by the conversion of each of the 180.degree. bend into substantially two 90.degree. bends (FIG. 8).

It should also be apparent that, if the end closure of FIG. 8 is used as a bottom end closure, i.e., inverted from the attitude shown, the bottom of the carton would be supported at the four corners thereof in a very stable configuration.

It should be further apparent that the panels may be of widths such that the formed carton may be either rectangular or square in cross-section.

While but two embodiments have been shown and described applying the supplemental score lines, other modifications thereof are possible within the scope of the following claims.