GB2101564A

GB2101564A - Carton formed from an ultrasonically weldable blank

Info

Publication number: GB2101564A
Application number: GB08137045A
Authority: GB
Inventors: Josef Jakob Buschor
Original assignee: Nolex Corp
Current assignee: Nolex Corp
Priority date: 1978-06-02
Filing date: 1978-12-01
Publication date: 1983-01-19
Also published as: FR2427253A1; JPS555375A; GB2101564B; FR2427253B1; CA1156988A; IT7852412A0; GB2022507A; IT1109335B; GB2022507B; DE2900625A1

Abstract

A carton is formed from an ultrasonically weldable blank having substantially rectangular, side wall portions (13, 15, 17, 19) contiguously attached to one another in side-by-side relationship, a top closure end (27) contiguously attached at one end of one side wall portion (13), a top sealing tab portion (37, 39 and 41) contiguously attached at one end of each of the other side wall portions, and webs (53, 55) interconnecting adjacent tab portions, said webs being at least half the width of said tab portions, whereby a continuous liquid- tight seal can be provided between the top closure end and the sealing tab portions and webs. <IMAGE>

Description

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SPECIFICATION

One-piece blank for forming a carton and a carton formed from same

The present invention relates to a one-piece blank for forming a carton having a liquid-tight end closure, and to a carton having a liquid-tight end closure.

The prior art includes one-piece, T-shaped blanks for forming cartons to hold liquids, such as beverages. One such prior art U.S.A. patent application was filed by Mitchell J. Matovich, Jr., on November 5th, 1976 and bears Serial No. 739,368. The T-shape in such prior blanks results from the provision of end closure panels at the opposite ends of one of the side wall panels of the carton. Each of the remaining side wall panels is provided at its ends with sealing tabs to be bent inwardly after the blank has been folded into the configuration of an open ended tube, and side seamed by means of a side seam flap carried by the same side wall panel with which the two end closure panels are associated. The free edges of the end closure panels are designed to be sealed to the sealing tabs on the ends of the side wall panels and, in the cited prior application as well as in most prior art used to form flat-ended cartons, the edges of the end closure panels, or at least the last of the end closure panels to be closed, and the sealing flaps on the side wall panels adjacent that end, are first heated to render the polyethylene or other material sealing the carton in a semi-molten condition. After such heating, the end closure panel is pressed onto the top of the previously formed carton side walls to close and seal the carton over its contained liquid.

The prior art also recognizes the fact that there are substantial advantages to utilizing ultrasonic energy as a means of heating and sealing cartons. Unfortunately, ultrasonic heating requires that the pair of carton edges being sealed to one another be placed underpressure between an ultrasonic horn and an anvil, these two members pressing toward one another during the application of ultrasonic energy.

Ultrasonic sealing involves the vibration of an ultrasonic horn relative to a stationary anvil which must be heavy enough to remain stationary in spite of the vibration of the ultrasonic horn against it. The marginal edges of the paper carton which are placed between the ultrasonic horn and the anvil are heated in the regions where they are hammered between the horn and anvil. The heating of these edges is dependent upon the pressure applied by the rapid hammering of the ultrasonic horn against the paperboard carton lying on the anvil. If the anvil is too light in weight, the anvil will vibrate with the ultrasonic horn, and very little relative motion will occur between the ultrasonic horn and the anvil. Therefore, very little heat will be induced in the paperboard carton. Furthermore, the anvil must provide a continuous area of support for the marginal edges beneath the ultrasonic horn in order for a continuous seal to be effected. In areas where the support provided by the anvil to the marginal edges is discontinuous, no heating will occur in the marginal edges, and therefore no seal will result in those areas. A further requirement for effecting a continuous seal is that the paperboard carton itself be continuous in the regions where a seal is to be effected. Thus, gaps or tears in the marginal edges will interrupt the formation of heat during the pounding of these edges between the ultrasonic horn and the anvil.

When sealing the side walls of a previously beverage-filled carton to the top end closure panel, it is impossible to place a sealing anvil inside of the container. Thus, no adequate means has been discovered to permit sealing such a carton utilizing ultrasonic energy.

If is believed to be known to form the upper carton end (after beverage filling) into a gable roof which permits a single gable roof seam to be sealed ultrasonically while being pinched between an ultrasonic horn and anvil which lie in a plane which is perpendicular to a plane defining the flat upper end of the carton. While such gable roofed cartons operate satisfactorily, they do not facilitate stacking on top of one another in a container, as is desirable when the beverage cartons are relatively small (as with one-half and one-third quart milk cartons). In addition, the formation of the gable top on these cartons requires a substantial increase in the amount of carton material required for the beverage container since typically the entire gable top is void of beverage and is simply extra paper stock material folded to provide the gable roof.

It is an object of the present invention to provide a one-piece bianktoform a carton having a liquid-tight end closure, and a carton formed from a one-piece blank, having a liquid-tight end closure.

There is provided by the present invention a one-piece blank for use, without other blanks, in forming a carton for liquids, said blank being particularly adapted to a carton forming process in which all seams are sealed using.ultrasonic energy, said blank being formed of paperboard coated with a material which melts in response to ultrasonic energy and comprising:

plural, substantially rectangular, side wall portions contiguously attached to one another in side-by-side relationship;

a closure end contiguously attached at one end of one of said side wall portions;

a sealing tab portion contiguously attached at the like end of each of the other side wall portions; and a web of said paperboard material interconnecting adjacent tab portions, said webs being at least half the width of said tab portions.

There is also provided by the present invention a carton formed from a one-piece blank comprising:

a first plurality-of side wall panels each extended at an end to form a sealing tab; the sealing tabs of adjacent wall panels

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connected together over at least half the width of each of said sealing tabs by interconnecting webs; and an end closure panel lying in a plane which is substantially perpendicular to each of said side wall panels, plural perimeter edges of said end closure panel being sealed at a joint to said plural sealing tabs, and said joint being formed along contacting surfaces of said end closure panel perimeter edges and said sealing tabs and interconnecting webs other than in a plane parallel to said side wall panels.

This invention preferably uses an anvil which is sufficiently heavy to provide the required static support to the paperboard carton during ultrasonic heating while at the same time providing a small lip which supports the sealing tab of the carton continuously around the adjacent side panels of the carton while the carton may be filled with liquid. The sealing lip is prevented from yielding to the ultrasonic vibrations of the ultrasonic horn by reason of its small extension from the body of the anvil. The extension of the lip on the anvil is therefore made at an approximately 45-degree angle, since this structural shape minimizes the inducement of vibrations in the lip by the ultrasonic horn. For this reason, the lip of the anvil merely folds the sealing tab a short distance below the top of the side panel. In order to prevent tearing or breaking of the sealing tab of the carton in the region of the corners between adjacent side panels of the carton, the lip of the anvil is formed with a gradual radius in the corresponding corners formed in the anvil. The sealing tab may be folded to form a double thickness wall portion, which also serves i to prevent tearing in the vicinity of the corners. The small size of the indentation of the tab effected by the sealing lip of the anvil also serves to minimize the strain in the vicinity of the corners of the sealing tab and thereby prevent tearing. 1

Thus, the invention can provide an ultrasonically sealed, flat top beverage container which facilitates nesting of one container above another during shipment. As will be appreciated, the above described blank has the sealing tabs at •] the ends of the adjacent side wall panels integral with one another, rather than separated from one another by a V-shaped cut as was common in prior art. The sealing tabs are connected by the interconnecting, corner, webs. These sealing tabs 1 with their interconnecting tabs thus run continuously around three sides of the carton once it has been formed into an open ended tube. The tabs may be bent inwardly to form, in effect, a double thickness wall portion at the upper 1

perimeter of the side wall panels.

After filling the carton with liquid, the upper wall portion formed by the sealing tabs and the side wall panels, together with the perimeter edge of the top end closure panel, are press formed 1 between adjacent die faces, the faces lying in a plane inclined at an angle preferably of approximately 45 degrees, with respect to the plane of both the upper end closure panel and the side wall panel being sealed. This pressing operation stretches the webs which interconnect the sealing tabs. In order to assure that this stretching does not rupture the webs interconnecting the sealing tabs at the carton corners, the carton is indented by the sealing die at a location immediately below the seal, so that the outermost position reached by the sealing tabs and their interconnecting webs is insufficient to cause tearing. When a double thickness is produced in the upper wall portion this also assists in prohibiting rupture at the sealed corners.

After the die has been used to form the adjacent sealing edges in the manner described above, an ultrasonic horn is placed against the perimeter edges, the contacting end of the horn also preferably defining a 45 degree angle plane relative the side wall and end closure panel of the carton. Application of ultrasonic energy to the perimeter margin then seals the upper end closure to the side wall panels.

After filling and sealing, as previously described, the carton forms a flat topped, polygonal structure which is adapted to nesting, one above the other, during shipment.

These and other advantages of the present invention are best understood through the following detailed description of the preferred embodiment which references the drawings, in which:

Figure 1 is a plan view of the carton blank according to the present invention used to form a carton;

Figure 2 is a perspective view showing the carton partially formed from the blank of Figure 1, but prior to closure of the upper end closure panel onto the side walls;

Figure 3 is a schematic, perspective view showing the partially formed carton of Figure 2 located within a schematically illustrated anvil and showing, in addition, the die used to compress the carton perimeter edges against the anvil;

Figure 4 is a perspective view of the carton formed by the apparatus and method step of Figure 3 after perimeter edge sealing;

Figure 5 is an enlarged sectional view taken along lines 5—5 of Figure 4 and showing the configuration of the carton end closure and side walls at the intersection of two such side walls;

Figure 6 is an enlarged sectional view taken along lines 6—6 of Figure 3 showing the interrelationship of the partially formed carton of Figure 2, the anvil and the die as the upper carton end is sealed;

Figure 7 is a sectional view similar to that of Figure 6 showing the die fully in place on the anvil; and

Figure 8 is a sectional view similar to that of Figures 6 and 7 showing the ultrasonic horn replacing the die above the anvil for the final sealing step of the method used for forming the carton.

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Detailed description of the preferred embodiment

Referring initially to Figure 1, the reference numeral 11 designates a polyethylene coated paperboard blank of T-shaped configuration from which a complete carton, sealed to be liquid tight, may be derived without requiring any other carton components. The blank is comprised of four carton side wall panels 13, 15, 17 and 19, delineated by indentation lines or scorings 21 along which folding of the blank into carton configuration may take place.

The wall panel 13 has integral therewith and delineated by indentation line or scoring 23, a lower carton end closure panel 25 which, in this particular instance, is square because the four side wall panels 13 through 19 are shown as being of equal width. If two side wall panels are to be of different widths than the other two, in alternation among the four, the resulting carton would be a rectangular cross section and not square and the end panel 25 would accordingly be rectangular and not square. If there were only three side wall panels instead of four, the end panel 25 would, of course, be triangular.

At the remaining end of the side wall panel 13, a top end closure panel 27 extends (without an indentation or scoring for delineation) from the side wall 13. The upper end wall 27 is wider than the lower end closure 25 or side wall 13 and, in addition, extends further from the side wall 13 than does the bottom end closure 25. The length and width of the end wall 27 is thus greater than the width of any of the panels 13—19. This increased size is required for overlapping sealing with the side wall panels 15—19 as will be understood as this description continues.

The side wall panels 15, 17 and 19 are each provided, at their lower ends, sealing flaps or tabs 29 delineated from the side wall panel by indentation or scoring lines 31 and delineated from one another by a pair of indentation of scoring lines 33, 35. The upper end of each of the panels 15, 17, and 19 is also provided with sealing flaps or tabs 37, 39, and 41, respectively, delineated by indentation or scoring lines 43, 45, and 47, respectively.

The prior art would suggest a separation of the tabs 37, 39, 41, one from another. In this case, however, they are connected by webs 53 and 55 of material. It has been found that these score lines 57 and 59 defining the webs preferably extend all the way to the score lines 43—47, but could stop somewhat short of those score lines so that the apexes of the triangular webs 53 and 55 are spaced slightly from the score lines 43—37.

Along its free edge, the side wall panel 19 is provided with a sealing tab 49 delineated by the indentation or scoring line 51.

Finally, in the case of a carton particularly adapted to hold potable liquids and provided internally with a sipper, as taught by Kalajian Patent No. 3,259,297, granted July 5, 1966, one of the side wall panels, for example the side wall panel 13, may be provided with a rectangular opening 53 adjacent to one end of the panel and extending parallel to the long dimension of the side wall 13. The opening is produced by cutting through the side wall panel to produce either a flap connected at one end or a complete opening, either of which will support a sipper which is mounted in a manner which permits its rotation about one end of the opening 53 so that it may be extended from the carton during use.

Whereas with prior designs the ends of the sealing flaps 37 through 41 were often cut away at an angle, the sealing flaps 37—41 of the blank 11, as indicated above, remain connected to one another by V-shaped web sections 53 and 55. Each of the scoring lines 57, 59 is at an angle of approximately 45 degrees with respect to the adjacent scoring lines 21, 43, 45, and 47. Scoring lines 57 and 59 typically intersect the scoring lines 21 at the scoring lines 43, 45, 47 to facilitate a right angle bend between the side panels 15, 17, 19.

The carton is shown in a partially formed condition in Figure 3, a number of steps having been accomplished to bring the carton to this stage of completion. The first step is to bend or flex the several wall panels at their scoring lines 21 to bring them around into the form of an open-ended tube, with the sealing tab 49 on the side wall panel 19 inside and overlapping the edge of the side wall panel 13. It is contemplated that the blank 11 wil| be formed of a paper stock coated with polyethylene to render it impervious to liquids and the formation of the blank into a seamed open ended tube is accomplished by placing a mandrel inside of the unseamed open ended tube and against the sealing tab 49, with ultrasonic energy being applied to the exterior surface of the panel 13 where it overlaps the tab 49. The ultrasonic energy partially melts the polyethylene on the two surfaces while the surfaces are held in contact with one another under pressure till the polyethylene fuses to effect a seal between these two surfaces.

After the formation of this seamed open ended tube, the bottom panel 25 can be sealed to the tabs 29 to close the bottom of the tube. This is generally accomplished by first folding the tabs 29 toward the interior of the seamed tube formed by the side walls 13 through 19, the score lines 33, 35 forming overlapping corner sections during this folding. The end 25 is then folded against the bottom of the open-ended tube and, in particular, into an overlapping relationship with the tabs 29. A mandrel is then placed on the inside or outside of the tube and against the overlapping portion of the end closure 25 and end tabs 29 and, on the opposite side, an ultrasonic horn is placed against the same overlapping members. Ultrasonic energy is then applied to seal the polyethylene on the confronting sections. It will be seen from the previous description that, in the case of the formation of the seamed tube as well as the closure of the bottom, it is possible, because there is no liquid within the tube, and because a portion of the tube remains open for

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access, to place a mandrel or anvil within the tube so that a confronting relationship between such a mandrel and an ultrasonic horn can be accomplished, with the parts to be sealed pinched 5 between these confronting members. In the present invention the open upper end of the tube shown in Figure 2 is also sealed ultrasonically at a time when liquid fills the carton, in circumstances in which a mandrel or ultrasonic horn cannot be 10 placed inside of the carton.

This is accomplished as shown in Figure 3. In order to aid in closing the carton, preferably the upper lid 27 may be folded to a closed position and released, prior to the condition of the carton 1 5 shown in Figures 2 and 3, in what can be considered to be a limbering operation. Polyethylene coated paperboard tends to have a memory so that, when relieved of the flexing pressure, the closure end 27 tends to self-restore 20 a part of the distance toward its original position lying in a plane parallel to the plane of the side

1 3. The position of the closure end 27 in Figures

2 and 3 is a reasonable representation of the attitude of this closure end 27 after the limbering

25 operation and prior to being pressed down and sealed. In addition, the lid has been preformed to have its marginal portions at all three non-hinged edges extend up at about a 45 degree angle. A limbering operation may also be completed on the 30 sealing tabs 37 through 41, and these tabs may be folded inwardly toward the centre of the open-ended tube and beyond this point, so as to lie flat against the upper portion of the wall panels 15 through 1 9. When released from this position, the 35 sealing tabs 37 through 41 will return partially toward the upper end of the carton, as shown, but will not return to a location which would make them coplanar. Rather, they remain folded below the level of the upper margin of the side panels 40 15—19.

Referring again briefly to Figure 1, it should be noted that, in order to fold the upper end closure panel 27 and the sealing tab 37 extending from the side panel 1 5 in separate directions, it is 45 necessary to cut these members apart from one another, as shown by the cut line 60. As will be fully understood through the description which follows, the cut line 60 extends only part-way from the free edge of the sealing tab 37 toward 50 the score line 43, but does not intersect the score line 43, so that a small link or web of continuous, uncut material remains between the tab 37 and the end closure panel 27.

Referring now to Figure 3, the carton filled with 55 liquid in its partially completed condition as shown in Figure 2, is placed in a three-sided anvil 61 constructed to conform with the outside surfaces of the container and to abut the side panels 15, 17, and 19. Accordingly, the anvil 61 60 is shown to include a back frame 63

interconnecting a lower U-shaped section 65 and an upper U-shaped section 67. As previously stated, at the time that the carton is placed into the anvil 61, it has been previously filled with fluid 65 and the upper end closure 27 has been partially closed. An upper die 69, having lower edges conforming with the upper edges of the anvil 61, is lowered, as shown by the arrow 71, onto the anvil 61 to compress the upper closure end 27 70 against the sides 13—19 of the container. This closure operation is best understood by reference to Figure 6.

As shown in Figure 6, the side wall 17 (and each of the other side walls in a similar manner) is 75 placed in abutting relationship with the upper U-shaped section 67 of the anvil 61. The bend formed at the score line 45 between the side panel 17 and sealing tab 37 is positioned above a diagonally bevelled upper edge lip 73 of the anvil 80 61 • The upper die 69 includes a bevelled edge 75 conforming with the bevelled edge lip 73, and this edge 75, when the die 69 is lowered and pressed onto the anvil 67, forces both the perimeter edge of the upper closure end 27, the sealing tab 39 85 and the upper perimeter portion of the side panel 17 into abutting relationship. This relationship is shown in Figure 7, the die 69 fully lowered onto and pressing against the anvil 67 and squeezing the three layers of material 39, 27, 17 which form 90 the sealing interface at the upper perimeter of the carton.

After the die 69 has been lowered into a squeezing relationship as shown in Figure 7, it is removed, and an ultrasonic horn 77, having a 95 bevelled edge 79 identical to the bevelled edge 75, is lowered into place on the anvil 67. Ultrasonic energy is applied by the horn 77 to the three layers of material 39, 27, 17 to heat the three layers and seal the polyethylene coating 100 thereon to form a sealed corner edge.

The three layers of material sealed at the edge lie substantially in a plane'designated in Figure 8 by numeral 81. This plane is inclined at an angle of approximately 45 degrees with respect to both 105 the upper end closure 27 and the side wall 17.

It should be noted that, while Figure 3 shows the die 69 moving straight down onto the anvil 67 (as shown by the arrow 71), the fact that the die 69 only abuts the anvil 61 on three sides may 110 require that the force applied to the die also have a horizontal component from right to left in Figure 7 as there is no pressure applied by the die at the hinged edge. In practice it is found that the resulting force on the die in Figure 7 should be 11 5 diagonally down and left. It may be preferable for the die 69 to reciprocate in a diagonal direction down and to the left in Figure 7 at an appropriate angle, to equalize the forces between the members to be sealed. It should also be 120 recognized that the remaining two sealing tabs 37 and 41 on carton sides 1 5 and 19 are sealed in a manner substantially identical to the sealing shown in Figure 6—8 of sealing tab 39 and side 1 7, three sides of the carton being sealed in this 125 manner. Each of these sealed sides facilitates,

through the use of a 45 degree angle bend of the sealed portions, the squeezing of the sealed members between the anvil 61 and ultrasonic horn 77.

130 The effect of this sealing method on the carton

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comer will be examined with reference to Figure 5. First, it will be noted through an examination of Figure 4 that the sealed portion of the carton side walls 1 5—19 extend outwardly beyond the plane 5 of the side walls 15—19. This creates a problem 70 of stretching of the material at the webs 53 and 55 as well as a stretching of the material in the area of the score lines 43, 45, 47 (Figure 1)

adjacent the webs 53 and 55 since the perimeter 10 dimension is increased. This stretching has a 75

tendency to rupture or tear the material at the corners. This tendency is reduced by a large radius corner bead 83 shown protruding from the corner of the anvil 61 at the lower extremity of 15 the bevelled edge lip 73. This protruding corner 80 bead 83 is reproduced identically in each of the two corners of the anvil 61 and produces in the two corners 87 and 89 (Figure 4) an indentation in the carton corner just below the sealing lip, in 20 this instance of not more than 0.254 cm inwardly. 85 As shown in Figure 5, this indentation 85 reduces to a negligible size, or even zero, the dimension 91 by which the sealed lip 93 of the carton must extend beyond the side wall 15 of the carton for a 25 predetermined length 95 of sealed lip 93. The 90 corner bead 83 also provides a larger radius bend at each of the carton corners 87, 89, which greatly facilitates the use of.ultrasonic energy for sealing. .

30 The extension 91 of lip 93 beyond the wall 15 95 determines the extent to which the corners 87 and 89 (Ffgure 4) of the carton are stretched during the sealing process. As can be seen from Figure 4, the upper end closure 27 of the carton 35 11 is compressed during the sealing operation, 100 whereas the side wall portions 15, 17, and 19 are each expanded at the sealed corners 87 and 89. If this expansion is sufficient, it will rupture the corners at the seal (at webs 54, 55) and cause a 40 leak in the container. The indentation 85 permits 105 a wide sealing lip 93 with an enlarged radius at its corners, while limiting or eliminating this extension 91.

As is best seen in Figure 2, the corner 97 45 formed between the sides 13 and 15 must also 110 seal with the end closure 27, and this seal is most difficult at the cut line 60 formed in the carton blank between the end tab 37 and the end closure 27. By making this cut line 60 end short of the 50 score line 43 (Figure 1), at which the sealing tab 115 37 is bent, it is possible to leave a short web of material between the end closure 27 and tab 37 extending toward the centre of the carton against which the end closure 27 can be sealed in order 55 to prevent any leaks at this corner. 120

As is best seen in Figure 4, the sealing lip 93 extending around three sides of the upper perimeter of the carton 11 at a 45 degree angle from the plane of the upper closure end 27 60 facilitates nesting of the bottom of one carton 11 125 within the perimeter of the top of a lower carton 90, when the cartons 11 and 90 are to be transported, as in a larger receptacle, stacked one on top of the other.

65 Throughout the description of this invention it 130

has been assumed that the carton, prior to being placed in the anvil 61, had been filled with a liquid 99 and that a sipper 101 had been attached and sealed within the opening 53, as shown in Figure 4, so that the carton 11 is closed except for the upper closure end 27, and filled.

While this embodiment is described as using a mandrel to form the carton sealing arrangement prior to use of a horn, alternatively the ultrasonic horn can perform both functions in a single step; especially if the horn is mounted for diagonal movement as discussed above.

The foregoing features will now be related specifically to the requirements of ultrasonically sealing the paperboard cartons. Referring first to Figure 5, the anvil 61, shown in cross-section, has the lip 73 extending out at approximately a 45 degree angle, instead providing a flat surface. In Figure 3, the lip 73 is shown to be continuous and unbroken in its support of the paperboard carton sealing tabs comprising the continuous sections 41, 39, and 37. It may also be noted that Figure 3 and Figure 4 clearly show that the continuous lip 73 of the anvil 61 extends into the body of the anvil 61 a very short distance. If, on the other hand, the lip 73, as illustrated in Figure 5, were flat and extended away from the carton sides for a substantial distance, such a lip would be more susceptible of vibrating with the ultrasonic horn 69, instead of remaining static, such that very little heat would be imparted to the sealing tab placed between the horn 69 and the anvil 61, and the larger degree of folding effected by such a lip would be more likely to cause a tear in the corners 87, 89 of the sealing tabs. Thus, the lip 73 is defined to extend a short distance at approximately a 45 degree angle. In order to avoid forming a tear between adjacent sealing tabs 37, 39, 41, the anvil is provided with a gradual radius on the bead in the vicinity of the corners between adjacent sealing tabs, as illustrated at 83 in Figure 3. Thus, instead of tearing the sealing tabs in the vicinity of these corners 53 and 55 of the blank, the sealing tabs are stretched instead by the bead in the vicinity of said corners. Thus, the carton provides a continuous sealing tab which is adequately supported by the anvil, which latter has a unique configuration minimizing vibration in the lip and eliminating tearing between adjacent sealing tabs of the carton. Because the lip extends diagonally away from the anvil body, the sealing tabs are sealed on a diagonal, with the top end closure panel parallel to the diagonal defined by the face of the sealing lip 73. Figure 6 and Figure 7 clearly show the sequence by which this diagonal sealing is effected.

There are three features which prevent breakage of the continuous sealing tabs of the carton. These features are directed to the area in which the stress is a maximum amount, namely, the outer corner edges 87 and 89, as shown in Figure 5. The first feature is the double fold of the perimeter edges to form two layers, as clearly shown in Figure 5. Thus, the stress is at a

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maximum along a folded portion 93 as shown in Figure 5 not along an outer edge of the sealing tab. This reduces the probability of tearing in the vicinity of the corners 87, 89, because the stress occurs in a region interior of the edges of the sealing tabs. The edges of the sealing tabs are more susceptable to tearing. Thus, the double fold eliminates any dependence upon the strength of the sealing tabs in the vicinity of their edges. A second feature which contributes to the continuity of the sealing tabs is clearly shown in Figure 5 in which the length 91 of the extension of the corner 89 of the sealing tab beyond the side wall panels 1 5 is kept to a minimum by a proper selection of the configuration of the anvil's sealing lip 73 and the bead 83. This eliminates the amount of stretching and strain induced in the corner region 87, 89. The amount of strain induced in the corner region 87, 89 is proportional to the distance 91 which the corner 87, 89 extend beyond the adjacent side wall panel 1 5, as shown in Figure 5. Thus,

minimization of the extending length 91 minimizes the strain and helps to prevent tearing of the sealing tab. The third feature which helps to prevent tearing of the sealing tabs 37, 39, and 41 in the vicinity of the corners 89 and 87 is the large radii of bead 83 provided on the sealing lip 73 in the vicinity of the corners 87 and 89. This reduces stress in the vicinity of the folds 85 of the indentation in the sealing tabs in the carton by providing a more gradual folding of the sealing tab to form the corners 87, 89.

It is pointed out that one-piece blank, the carton and anvil are also illustrated in copending application No. 46791/78 on which the present application was divided.

Claims

Claims

1. A one-piece blank for use, without other blanks in forming a carton for liquids, said blank being particularly adapted to a carton forming process in which all seams are sealed using ultrasonic energy, said blank being formed of paperboard coated with a material which melts in response to ultrasonic energy and comprising:

plural, substantially rectangular, side wall portions contiguously attached to one another in side-by-side relationship;

a closure end contiguously attached at one end of one of said side wall portions;

a sealing tab portion contiguously attached at the like end of each of the other side wall portions; and a web of said paperboard material interconnecting adjacent tab portions, said webs being at least half the width of said tab portions.

2. A one-piece blank as defined in claim 1, additionally comprising:

a web of said paperboard material extending between an adjacent one of said sealing tab portions and said closure end.

3. A one-piece blank as defined in claim 1 or 2, wherein said interconnecting webs have the same width as said tab portions.

4. A one-piece blank as defined in claims 1, 2 or 3, wherein the width of said closure end is greater than the width of said one of said side wall portions.

5. A one-piece blank as defined in claim 4, wherein the length of said closure end is greater than the width of any of said wall portions.

6. A one-piece carton blank substantially as hereinbefore described with reference to the accompanying drawings.

7. A carton formed from a one-piece blank comprising:

a first plurality of side wall panels each extended at an end to form a sealing tab;

the sealing tabs of adjacent wall panels connected together over at least half the width of each of said sealing tabs by interconnected webs; and an end closure panel lying in a plane which is substantially perpendicular to each of said side wall panels, plural perimeter edges of said end closure panel being sealed at a joint to said plural sealing tabs, and said joint being formed along contacting surfaces of said end closure panel perimeter edges and said sealing tabs and interconnecting webs other than in a plane parallel to said side wall panels.

8. A carton as defined in claim 7, wherein said first plurality of side wall panels intersect to form carton corners, said corners each including an indentation immediately adjacent said joint to relieve stresses and reduce the amount by which said joint extends laterally beyond said corner.

9. A carton as defined in claim 7 or 8, wherein said joint formed along contacting surfaces lies in a plane which is oriented at substantially 45 degrees from the plane of said end closure panel.

10. A carton as defined in claim 7, 8 or 9, wherein said side wall panels are folded relative one another to form carton corners, the radius of said carton corners being smaller than the radius of said joint adjacent said carton corners.

1 1. A carton as defined in any of claims 7 to

10, additionally comprising:

a connecting link of material between said end closure panel and an adjacent one of said plural sealing tabs.

12. A carton as defined in any of claims 7 to

11, wherein in forming the carton, said plural sealing tabs are each folded flat against the respective adjacent wall panels.

13. A carton as defined in claim 12, wherein said sealing tabs are folded flat against respective wall panels to form a perimeter fold, said fold in said completed carton having a longer perimeter dimension than have said respective adjacent wall panels in combination.

14. A carton as defined in claim 12 or 13, wherein three layers comprising said sealing tabs, a portion of said side wall panels and a perimeter portion of said closure panel are all sealed together to form said joint.

1 5. A carton as defined in any of claims 7 to 14, wherein said end closure panel is intended in use to be the upper one, and said joint is formed

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in a manner which facilitates stacking of a plurality of the cartons, one on top of the other.

16. A carton as defined in claim 15, wherein said joint extends above the plane of said end closure panel to nest the bottom end of an identical carton above said carton.

17. A carton formed from a one-piece blank as defined in any of claims 1 to 6.

18. A carton, formed from a one-piece blank substantially as hereinbefore described with reference to the accompanying drawings.

New Claims or Amendments to Claims Filed on 22nd July i982 Superseded Claims 1—8

New or Amended Claims

1. A one-piece blank for use, without other blanks in forming a carton for liquids, said blank being particularly adapted to a carton forming process in which all seams are sealed using ultrasonic energy, and being formed of paperboard coated with a material which melts in response to ultrasonic energy, said blank comprising a plurality of substantially rectangular side wall panels contiguously attached to one another in side-by-side relationship to form a row of said side wall panels; a single bottom end panel contiguously attached at a bottom end of one of said side wall panels; a single top end closure panel attached at a top end of the side wall panel at one end of said row; a sealing tab portion contiguously attached at the top end of each of the other side wall portions; and webs of said paperboard material each interconnecting two adjacent tab portions, said webs being at least half the width of said tab portions.

2. A one-piece blank as claimed in claim 1, additionally comprising a web of said paperboard material extending between an adjacent one of said sealing tab portions and said top end closure panel.

3. A one-piece blank as claimed in claim 1 or

2, wherein said interconnecting webs have the same width of said tab portions.

4. A one-piece blank as claimed in claim 1, 2 or

3, wherein the width of said top end closure panel is greater than the width of side wall panel to which it is attached.

5. A one-piece blank as claimed in claim 4, wherein the length of said top end closure panel is greater than the width of any of said wall panels.

6. A one-piece carton blank substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

7. A carton formed from a one-piece blank comprising a plurality of side wall panels, each of which except for one, is extended at its top end to form a sealing tab, the sealing tabs of adjacent wall panels being connected together by interconnecting webs; a bottom end closure panel attached to said side wall panels and sealing off the bottom of said carton; and a top end closure panel lying in a plane which is substantially perpendicular to each of said side wall panels and joined to said one side wall panel along a fold line, perimeter edges of said top end closure panel being sealed at a joint to said sealing tabs to form a projecting rim with rim corners at said webs, said rim corners having inwardly projecting indentations just below said rim.

8. A carton as claimed in claim 7, wherein said rim lies in planes which are oriented at substantially 45 degrees from the plane of said top end closure panel.

9. A carton as claimed in claim 7 or 8, wherein the radius of the carton corners at which said side wall panels are folded relative one another is smaller than the radius of said joint at said indentations.

10. A carton as claimed in claim 7, 8 or 9, additionally comprising a connecting link of material between said top end closure panel and an adjacent one of said sealing tabs.

11. A carton as claimed in any of claims 7 to 10, wherein in forming the carton, said sealing tabs are each folded flat against the respective adjacent wall panels.

12. A carton as claimed in claim 11, wherein said sealing tabs are folded flat against respective wall panels.

13. A carton as claimed in claim 11 or 12, wherein three layers comprising said sealing tabs, a portion of said side wall panels and a perimeter portion of said closure panel are all sealed together to form said rim.

14. A carton as claimed in any of claims 7 to 1 3, wherein said joint is formed in a manner which facilitates stacking of a plurality of the cartons, one on top of the other.

1 5. A carton as claimed in claim 14, wherein said joint extends above the plane of said tab end closure panel to nest the bottom end of an identical carton above said carton.

16. A carton formed from a one-piece blank as claimed in any of claims 1 to 5.

1 7. A carton formed from a one piece blank, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

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Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained