US3452919A - Double layer tape seal on container slit opening - Google Patents

Description

July 1, 1969 D. R. AVQLIO DOUBLE LAYER TAPE SEAL ON CONTAINER SLIT OPENING Filed April 5, 1968 Sheet of 3 INVENTOR. D.R. AVOLI O BY wf'wj A T TORNEVS y 1, 1969 D. R. AVOLIO 3,452,919

DOUBLE LAYER TAPE SEAL 0N CONTAINER SLIT OPENING Filed April 5, 1968 Sheet 2 of 3 INVENTOR. D.R. AVOL IO AT TORNEYS July 1, 1969 D. R. AVOLIO 3,452,919

DOUBLE LAYER TAPE SEAL ON CONTAINER SLIT OPENING Filed April 5, 1968 Sheet 3 of s F G. 4 INVENTOR.

on. AVOLIO BY 2mg);

A TTORNEVS United States Patent US. Cl. 229-17 9 Claims ABSTRACT OF THE DISCLOSURE A polyethylene-backed aluminum foil tape is heat sealed over the area on a gable top plastic coated paperboard milk carton blank where the slit opening is to be die cut. Subsequently the opening is die cut through both the tape and the blank. A second polyethylene-backed aluminum foil tape is sealed over the slit in the first tape. The formed, filled and sealed carton is opened by peeling the second tape from the first tape, leaving a neat appearing, sanitary slit opening.

Gable top containers of the type disclosed in Wilcox, U. S. 3,295,739, are formed of thermoplastic coated paperboard and are provided with a weakened line of severance to form the pouring lip when the container is opened. The weakened line of severance is covered in the sealed container by a tape which is heat sealed to the thermoplastic coating on the container. When this tape is removed from the container in the process of initially opening the container, the adhesion between the tape and the thermoplastic coating on the paperboard exceeds the strength of the outer fibrous layer of the paperboard with the result that the outer layer of fibers is removed, leaving a roughened fibrous surface. Although this roughened surface has the advantages of being a fresh, clean, sterile surface, it permits the paperboard to readily absorb part of the liquid contents being poured from the container. While this does not present any significant disadvantages with milk, due to the similarity in color to the paperboard, severe discloration is experienced with other liquids which differ in color from the paperboard. Furthermore, the roughened surface reduces the aesthetic value of the container even in the absence of discloration.

In accordance with the invention, it has been discovered that the foregoing disadvantages can be avoided by bonding a first tape to the container blank prior to forming the slit or weakened line of severance, cutting the weakened line of severance through the first tape and the blank, and subsquently utilizing a second tape over the first tape to seal the weakened line of severance in the first tape. The first tape is a laminate with the back surface being a thermoplastic material which is compatible with and heat sealable by welding, or mutual fusion, to the thermoplastic coating on the container blank to form a bond which is stronger than the bond between the fibers in the paperboard substrate of the container blank. The outer surface of the first tape is a nonporous material which has a melting point substantially higher than the melting point of the thermoplastic backing of the first tape of the thermoplastic backing of the second tape. The thermoplastic backing of the second tape is heat sealable by hot melt adhesion to the outer surface of the first tape to form a peelable bond, which is preferably weaker than the bond between the fibers in the fiberboard. In initially opening a formed and sealed container, the second tape is peeled from the first tape leaving the smooth, attractive outer surface of the first tape on the spout lip.

Accordingly, it is an object of the invention to provide an improved container having a weakened line of severance protected by a tape. It is an object of the invention to eliminate the raw paperboard edge on a container spout opening caused by delamination of the paperboard upon removal of a cover tape. Another object of the invention is to increase the ease of opening a container having a weakened line of severance covered by a sealing member. A further object of the invention is to enhance the aesthetic value of a container. Another object is to minimize contact of the liquid contents of a container with raw paperboard during dispensing.

Other objects, aspects and advantages of the invention will be apparent from a study of the specification, the drawings and the appended claims to the invention.

In the drawings, FIGURE 1 is a perspective view of a gable top container to which the invention is applicable; FIGURE 2 is a plan view of the paperboard blank, having the first tape thereon, from which the container of FIGURE 1 is formed; FIGURE 3 is a perspective View of the gable top structure of the container of FIGURE 1 in a partially opened condition; and FIGURE 4 is a perspective view of the gable top structure of FIGURE 3 in the fully opened condition.

Referring now to FIGURE 2, the rectangular blank of paperboard having a coating of polyethylene on front and back, is provided with vertical score lines 12, 13, 14 and 15, extending upwardly from the lower edge of the blank to a series 16 of horizontally extending score lines 16a, 16b, 16c, 16d, and 16:2. The score lines 13, 14 and 16b define a front side wall panel 17. Score lines 15 and 16d, and 12 and 16a define panels 18 and 19, the free edges of which, in the formed container, are overlapped and joined by a permanent adhesive bond to form a rear side wall panel which is located opposite front side panel 17. End wall panels 21 and 22 are defined by score lines 12, 13 and 16a and 14, 15 and 160, respectively. Horizontal score lines 16a and 16c are located lower on the container than score lines 16b, 16d and 16e to substantially reduce the thickness of the folds at adjacent lower corners of the closure panels. In other words, the spacing apart in the vertical plane of the bend of each roof panel into its vertical container wall from the bend of each end closure panel into its vertical container wall permits smaller and more attractive folds in the resulting corners of the container. With the scoring arrangement shown in FIGURE 2, the panels 17, 21, 22 and the rear wall panel formed by panels 18 and 19 are all of equal width.

The vertical score lines 12, 13, 14 and 15, which are located at the vertical corners of the completed container, extend upwardly past score lines 16 as 23, 24, 25 and 26, and terminate at the top edge of the blank. Horizontal score line 27 is located a short distance downwardly from the top edge of the blank.

When the blank has been folded to tubular form and overlapping edges of the panels 18 and 19 have been joined together, a bottom closure 20 (FIGURE 1) is permanently sealed to the lower end of the tubular formation. Score lines 24, 25, 16b and 27 define the front roof closure panel 28. Score lines 24, 25 and 27 define the rib panel 29, surmounting the front roof panel 28. Score lines 23, 26, 16a, 16e and 27 define the rear roof closure panel composed of sections 31 and 32. Score lines 26, 23 and 27 define the rib panel, comprising sections 33 and 34, surmounting the rear roof panel. Score lines 23, 24, 16a and 27 define a rectangular end closure panel. This end closure panel is provided with converging score lines 35 and 36 which, at their upper ends, intersect the score line 27 medial of score lines 23 and 24, thus defining a triangular end closure panel portion 37 and a pair of triangular foldback panel portions 38 and 39. Score lines 23, 24, 27 and 41 define rib panels 42 and 43,

surmounting fold- back panel portions 38 and 39, respectively. Score lines 25, 26, 16c and 27 define a second rectangular end closure panel. This second end closure panel is provided with converging score lines 44 and 45 which, at their upper ends, intersect score line 27 medial of score lines and 26, thus defining a triangular end closure panel portion 46 and a pair of triangular fold- back panels 47 and 48. Score lines 25, 49, 26 and 27 define ridge panels 51 and 52, surmounting fold- back panel portions 47 and 48, respectively. In the completed container, the pair of opposed roof panels 28 and 31, 32 are inclined toward each other and overlie the top of the tubular body formed by side walls 17, 21, 22 and 18, 19. The pair of opposed triangular end closure panels 37 and 46 are infolded between roof panels 28 and 31, 32 from the opposite gable ends formed by the latter, and with their apexes located at the central area of the gable. The fold lines 44, 45, 35 and 36 which join each pair of triangular fold- back panels 47, 48 and 38, 39 to the opposite sides of triangular end closure panels 46 and 37 are in proximity with the roof panels, the fold-back panels being folded against the underside of said roof panels. Ridge panels 51 and 52 surmounting fold- back panels 47 and 48 are hinged together at the apex of end closure panel 46 and are folded about the hinge joinder score line 49 in face-to-face relation, between the ridge panels 29 and 33 surmounting the roof panels. Similarly, ridge panels 42 and 43 surmounting fold- back panels 38 and 39 are hinged together at the apex of end closure panel 37 and are folded about the hinge joinder score line 41 in face-to-face relation, between ridge panels 29 and 34. The ridge panels are heated to form a bond between the contacting thermoplastic coatings to form the ridge structure of the gable top.

Score lines 23, 24, 25 and 26 are of extended width, with respect to the remainder of score lines 12, 13, 14 and 15, with the extension being in a direction toward the center of the respective roof panel. Thus score lines 24 and 25 are of extended width in the direction of the center of the front roof panel 28, while score lines 23 and 26 are of extended width in a direction toward the center of the rear roof panel formed by panels 31 and 32.

When the blank of FIGURE 2 is folded on the score lines 12, 13, 14 and 15 about the square mandrel of the container erecting machine, the closure panels above the series of score lines 16 form a square tubular cross section in a direction transversely of the container. When the top closure panels are folded inwardly, the greater width of score lines 23, 24, 25 and 26 provides extra material for the end closure panels 46, 47, 48 and 37, 38, 39 and surmounting rib panels 51, 52 and 42, 43, whereby in the formed and sealed container, rib panels 43 and 51 have a greater combined length than rib panel 29 surmounting the front roof panel 28. Similarly rib panels 52 and 42 have a greater combined length in the formed and sealed container than the rib panel formed by panels 33, 34 surmounting the rear roof panel 31, 32. This, in turn, results in the hinge joints on score lines 41 and 49 abutting or slightly overlapping at the center of the laminar ridge structure formed by bonding the rib panels together.

In order to provide a snap action for opening and closing the pouring spout, the front roof panel 28 is provided with score lines 71 and 72, extending upwardly from the intersection of horizontal score line 16b and vertical score line 25 to a point on score line 27 midway between vertical score lines 24 and 25. Score line 71 is preferably formed in three sections 71a, 71b and 71c. Score line 72 is preferably formed in three sections 72a, 72b and 720. Straight line sections 71b and 72b are substantially parallel to an imaginary line 73 between the point on score line 27 midway between score lines 24 and 25 and the intersection of score lines 16b and 25.

Imaginary line 73 closely approximates the plane of the triangular end closure panel 46 in the infolded, sealed condition. If side walls 17 and 18, 19 were of greater width than walls 21 and 22, score line sections 71a and 72a would intersect score line 27 at or closely adjacent to the intersection of imaginary line 73 with score line 27, or in other words at or closely adjacent to the intersection of the score line 27 with the plane of panel 46 in the infolded, sealed condition of the container. Score section 72b is positioned in roof panel 28 above the imaginary line 73 while score section 71b is positioned in roof panel 28 below imaginary line 73. Score sections 710 and 720 extend from the lower ends of score sections 71b and 72b, respectively, to converge together at the intersection of score lines 16b and 25. Score sections 71a and 72a extend from the upper ends of score sections 71b and 72b, respectively, to the point on score line 27 midway between score lines 24 and 25. The rear roof panel 31, 32 is provided with score lines 74 and 75, corresponding to score lines 71 and 72, respectively, comprising score sections 74a, 74b, 74c, and 75a, 75b, 75c, respectively.

In the second end closure panel, which serves as the pouring spout, converging score lines 44 and 45 intersect horizontal score line 27 midway between score lines 25 and 26. Vertical score line 49 extends upwardly from the intersection of score lines 44 and 45 to the top edge of the blank. A first tape 66 comprising a backing layer of polyethylene laminated to an outer layer of aluminum foil is heat sealed to the second end closure panel by mutual fusion of the backing layer to the polyethylene coating on the blank. The weakened line of severance or slit is located in the upper part of panel portions 47, 46 and 48 below horizontal score line 27 and extends through both the blank and tape 66. The weakened line of severance is formed in three sections, each end section 60a and 60b being formed by a series of zig-zag incisions, and the center section 600 being formed by a straight, horizontal incision. The weakened line of severance 60 would intersect score lines 44 and 45 except that score lines 44 and 45 are discontinuous, or interrupted, in the area of the weakened line of severance 60. Score lines 44 and 45 stop short of line 60 to prevent leakage which could otherwise occur by capillary action through the slit and along the score lines. Eliminating all score line grooves in the vicinity of the line 60 provides a fiat surface completely around the periphery of the slit, thus permitting a liquid tight seal to be effected between the first, or inner, tape 66 and the container, and also a liquid tight seal between the first tape 66 and the second, or outer, tape 61 (FIGURE 3).

A second strip of tape 61 (FIGURE 3) comprising a backing layer of polyethylene laminated to an outer layer of aluminum foil, is peelably heat sealed to the outer aluminum layer of tape 66 in overlying relation to the weakened line of severance 60. The tape 61 is applied over the weakened line of severance 60 and heat sealed to the entire marginal surface about the weakened line of severance.

The first tape 66 is heat sealed to the blank prior to the formation of the weakened line of severance 60, while tape 61 is preferably bonded to tape 66 after the blank has been folded on score lines 12, 13, 14 and 15 to form a tubular body, but prior to the continued folding of the blank to form the gable top structure. This eliminates possible damage to the seal between tapes 61 and 66 would could occur during the handling of the blanks if tape 61 were added earlier, and minimizes the possibility of accidently causing a fold along the weakened line of severance during the formation of the gable top structure. The ends 62 of tape 61 extend beyond the ends of the second end closure panel to provide grasping tabs, while tape 66 does not extend outside of the second end closure panel. In one embodiment, tape 66 is stopped short of the edge of the second end closure panel to permit a fusion type heat seal between the poleythylene coating on the end closure panel and the portion of tape 61 which overlies the exposed portion 67 (FIGURE 3) of the end closure panel. This tacking of tape 61 at the outer ends of tape 66 minimizes the possibility of accidental separation of tape 61 from tape 66.

During the initial opening of the container of FIGURE 1, outwardly directed pressure is applied against panels 47 and 48 to delaminate the bond between panels 51 and 52 and the panels 47 and 48 are folded outwardly and backwardly (toward the opposite gable end) to the position illustrated in FIGURE 3. One end 62 of tape 61 is grasped and tape 61 is peeled from tape 66, leaving the clean, attractive, unspoiled aluminum foil surface of tape 66 as the exterior surface of the lip of the pouring spout. Panels 47 and 48 are then folded further backward and inwardly directed pressure is applied along fold lines 25 and 26 to pop out the lower portions of panels 46, 47 and 48 to form the pouring spout illustrated in FIGURE 4.

While tapes 61 and 66 have been described in terms of the presently preferred laminated aluminum foil tape having a polyethylene backing, tapes of other materials can be employed. The backing layer of the first tape should be a thermoplastic material which is compatible with and heat sealable by mutual fusion to the thermoplastic coating on the paperboard blank. It is presently preferred that the backing of the first tape be the same thermoplastic material which is utilized to coat the paperboard. Various homopolymers of ethylene or propylene and copolymers of ethylene or propylene with each other and/or with at least one other mono-l-olefin having from 4 to carbon atoms per molecule or a diolefin having from 4 to 10 carbon atoms per molecule, and polymers of vinyl chloride alone or with suitable comonomers can be employed as the backing for the second tape as well as the backing for the first tape and as the coating for the paperboard. The outer layer of the first tape should be nonporous to prevent or minimize mechanical bonding with the backing of the second tape and should have a melting point above the melting point of the backing for the first tape as well as above the melting point of the backing of the second tape to prevent mutual fusion with the backing of the second tape and sticking to the sealing equipment for applying the first tape to the blank. Suitable materials for the outer layer of the first tape include metal foils, for example aluminum foil, tin foil; polyesters, for example polyethylene terphthalate; polyamides, for example nylon; fiber glass; cellophane; and papers or fibrous material sized with a high temperature sizing, for example sodium silicate. While the outer layer of the second tape can be of any of the materials given for the outer layer of the first tape, it is presently preferred that the outer layer of the second tape be of a heat reflective material, such as a metal foil, to protect the bond of the first tape to the container and the bond of the second tape to the first tape during the radiant heating of the ridge panels preparatory to the formation and sealing of the gable top structure.

While the invention has been described in terms of a particular type of gable top container, it is applicable to other types of paperboard containers utilizing a cover sheet to protect an opening therein.

Reasonable variations and modifications are possible within the scope of the foregoing disclosure, the drawings and the appended claims to the invention.

I claim:

1. A container formed of paperboard coated with a first thermoplastic material, a first cover sheet having a backing surface of a second thermoplastic material compatible with and heat sealed to said first thermoplastic material by mutual fusion, said first cover having an outer surface of a nonporous material having a melting point significantly above the melting point of said second thermoplastic material, an opening in said container through said first cover sheet, a second cover sheet hav ing a backing material of a third thermoplastic material which has a melting point significantly below the melting point of the outer surface material of said first cover sheet and which is heat sealed to the outer surface of said first cover sheet entirely around said opening by a peelable bond to seal said opening.

2. A container in accordance with claim 1 wherein a portion of said second cover sheet extends beyond said first cover sheet and the backing material of a first part of said portion is heat sealed by mutual fusion to said first thermoplastic material and a second part of said portion is unbonded, thereby providing a grasping tab.

3. A container in accordance with claim 1 wherein each of said first, second and third thermoplastic materials is a polymer of ethylene, and said outer surface material of said first cover sheet is a metal foil.

4. A container in accordance with claim 1 wherein said container is a gable top container having a pouring spout panel, said opening being a weakened line of severance in said pouring spout panel.

5. A contatiner in accordance with claim 4 wherein said gable top container comprises a tubular body, a bottom closure fixed to said body, a pair of opposed roof panels inclining toward each other and overlying the top of said body, a pair of opposed triangular end closure panels infolded between said roof panels from the opposite gable ends formed by the latter, first and second pairs of triangular fold-back panels, each pair of triangular fold-back panels being joined to the opposite sides of a respective one of said triangular end closure panels along fold lines which are in proximity with said roof panels, said fold-back panels being folded against the underside of said roof panels, a ridge panel surmounting each of said roof panels, a ridge panel surmounting each of said fold-back panels, each pair of ridge panels surmounting a pair of fold-back panels being hinged together at the apex of the contiguous end closure panel and being folded about such hinge joinder in face-to-face relation, between the ridge panels surmounting said roof panels.

6. A container in accordance with claim 5 wherein said opening is a weakened line of severance located in the rectangular end closure panel formed by one of said triangular end closure panels and its associated pair of triangular fold-back panels, said weakened line of severance lying solely within the upper portion of said reetangular end closure panel below the respective surmounting ridge panels and extending transversely of said rectangular end closure panel and terminating at its ends in spaced relation to the side edges of said rectangular end closure panel.

7. A container in accordance with claim 6 wherein the outer surface of said second cover sheet is a radiant heat reflective material.

8. A container in accordance with claim 7 wherein each of said first, second and third thermoplastic materials is a polymer of ethylene.

9. A container in accordance with claim 8 wherein the outer surface of each of said first and second cover sheets is a metal foil.

References Cited UNITED STATES PATENTS 3,217,966 11/1965 Kelly 229-l7 3,295,739 l/l967 Wilcox 229-17 3,348,755 10/1967 MacEwen 229l7 DAVID M. BOCKENEK, Primary Examiner.

U.S. Cl. X.R. 229-37, 51

Images