WO1990014275A1

WO1990014275A1 - Improvements in carton manufacture

Info

Publication number: WO1990014275A1
Application number: PCT/GB1990/000796
Authority: WO
Inventors: Richard Emerson
Original assignee: Fall Line Design
Priority date: 1989-05-19
Filing date: 1990-05-21
Publication date: 1990-11-29
Also published as: GB8911560D0

Abstract

The end closure or an intermediate closure of a carton made of foldable e.g. cellulosic material comprises, all around a conventional hollow carton shape rectangular in cross-section, three transverse fold lines (16, 17, 18) and (at each side) diagonal fold lines (19, 20). Lines (16 and 18) intersect the carton side folds to define a square a-b-c-d. Line (17), front and back, is folded inward, (Fig. 2b) untill the apex lines (17) meet inside the carton (Fig. 2c, Fig. 2d). Line (17) carries a strip of suitable wax, adhesive, sealant or compressible foam inside the carton to form a closure along the meeting apex lines. Protruding portions (24), corresponding to diagonal folds (19, 20) are folded downwards (Fig. 2e) and further align, unite and strengthen the closure formed along these apex lines.

Description

IMPROVEMENTS IN CARTON MANUFACTURE

This invention relates to the manufacture of cartons from foldable, usually cellulosic, material.

The production of cellulosic cartons is a common and ^■widespread technology. Some cartons are fabricated to be containers only. Others are sealed against long term or rapid ingress of air or water, or escape of contents. Some cartons are hermetically, that is to say airtight sealed, and provided with a waxed or polymer-clad surface to ensure such seal. Cartons can have a tear apart, single-use closure, or can be openable and closable. They can be configured to assist use after opening, e. g. to form a pouring spout. Some carton fabrication involves special requirements, for example heavy duty cartons, cartons for medical or pharmaceutical products, etc. Most cartons carry advisory, advertising, or promotional literature or diagrams and the like.

The present invention relates to a novel feature of carton construction potentially useful in all of the above indicated respects. It also provides other modes of carton use hitherto either not achievable or achievable only at disproportionate expense.

In one aspect the invention consists in a carton in which a closure is formed by the approach and contact to a recipient region of the apex line or of a linear apical zone of a folded elongate indentation of generally V-shaped cross-section: where the said apex line or zone carries or borders upon a linear extent of material alterable to provide a closure member as contact is effected.

The another aspect the invention consists in a carton in which a closure is formed by the approach and contact of the apex lines or of linear apical zones of two folded elongate indentations each of generally V-shaped cross-section: wherein at least one of the apex lines or linear apical zones carries or borders upon a linear extent of material alterable to provide a closure member as contact is effected.

The apex line is typically a single fold line, considered at the outside of the V-shaped cross-section.

The apical zone is typically a narrow region located between two fold lines, e. g. a narrow flat zone with parallel edges. If desired it can itself possess a similar third, parallel, fold line, which can be folded inwardly or outwardly in relation to the general V-shape.

The ' linear extent of alterable material' can depending on its composition be a thin strip ox layer of material extending along the apex line or apical zone, or can be a thicker such strip, identically positioned but protruding above the surface. It can in some cases be a thicker strip of material located along beside the apex line or apical zone.

In composition of the alterable material can vary, and will affect its physical form and placement. Thus, it can be resiliently deformable, e. g. a narrow strip of cellular elastomeric material, altering by way of deformation on closure but regaining its original shape (or most of it) on reopening of the carton. It can be deformable but not resilient, e. g. a layer of a sealant of putty-like consistency, the "alteration" again being an alteration of shape. It can be alterable by melting, e. g. as a wax. In this case, it could lie either along the line or apical zone, or to one side thereof, if melting causes the material of molten strip to run across the joined lines (e.g. to merge with another such molten strip) without other deforming pressure.

In any of the above instances the material can be adhesive e. g. a re-sealable low-tack adhesive, so that opening and reclosing are permitted. Adhesiveness while often advantageous is however not invariably necessary.

Preferably, the linear extent of alterable material is present along each of two mutually contac able apex lines or apical zones as a strip of tacky re-sealable sealant.

It falls moreover within the scope of the invention to incorporate into the closure components at least one pre-existing member to extend in closure across the gap. This member can be constituted by, for instance a strip of paper folded into an X-shaped cross section, or a V-shape cross-section. Alternatively it could be a thin, similarly shaped, polymer strip.

The closure can be an end closure or an intermediate closure dividing the carton into mutually closed or sealed internal regions. Using the closure a ulticompartment carton can be built up.

In another aspect the invention consists in a method of forming a carton with an intermediate closure, from a blank of foldable material, comprising the steps of

(a) taking a blank of material having parallel side edges and having thereon four notional, indicated or pre-for ed longitudinal fold lines parallel to those edges to define a face portion, and two side portions of mutually equal width such that the blank can be folded into a hollow shape of rectangular cross-section with the marginal portions overlapping and secured together,

(b) noting, marking or forming completely across the blank three transverse fold lines at right angles to the original four, longitudinal lines the outer two such transverse lines being spaced by a distance identical with that between the longitudinal fold lines defining the side portions and the central transverse line extending exactly halfway between the outer lines,

(c) noting, marking or forming two diagonal fold lines between opposed corners of the square on each side portion defined by the intersections of the longitudinal lines and the outer transverse lines,

(d) applying along the central transverse fold line a strip of material alterable to provide a closure,

(e) folding the blank longitudinally to its hollow shape of rectangular cross-section with the strip of alterable material inside, and securing the margins where they overlap, (f) folding in the central transverse fold line at the faces of the carton until the apex lines meet internally to form a closure with the alterable material, and

(g) folding downwards the folded side portions corresponding to the diagonal fold lines to further align and unite the apex lines by means of the strip of alterable material.

In a closely related aspect the invention consists in a method of forming a carton with an end closure, from a blank of foldable material, comprising the steps of:

(a) taking a blank of material having parallel side edges and a top edge at right angles thereto, and having thereon four notional, indicated or preformed longitudinal fold lines parallel to those edges to define a face portion, and two side portions of mutually equal width such that the blank can be folded into a hollow shape of rectangular cross-section with the marginal portions overlapping and secured,

(b) noting, marking or forming completely across the blank two transverse fold lines at right angles to the original four longitudinal lines, the lower fold line being spaced from the top edge by a distance identical with that between the longitudinal fold lines defining the side portions and the other transverse line extending exactly halfway between the outer lines,

(c) noting, marking or forming two diagonal fold lines between opposed corners of the square on each side portion defined between the longitudinal lines, lower transverse fold line, and top edge,

(d) applying along the said other transverse fold line a strip of material alterable to provide a closure,

(e) folding the blank longitudinally to its hollow shape of rectangular cross-section, with the strip of alterable material inside, and securing the margins where they overlap,

(f) folding in the central transverse fold line at the faces of the carton until the apex lines meet internally to form a closure with the alterable material, and

The invention will he further described with reference to the accompanying drawings., in which: -

Figures la to le show a prior art carton construction and indicate respectively (a) the top of a carton before folding, (b) the top of a carton while folding is taking place, (c) the top of a carton just prior to complete folding, (d) a cross-section through lines I-I of Figure lc, and (e) a side view of the top of a folded carton;

Figures 2a to 2e indicate the closure of a carton in accordance with the invention, and show respectively (a) the top of the carton before folding, (b) the top of a carton partially deformed to close; (e) the top of a carton immediately prior to complete folding; (d) a cross-section along lines II-II of Figure 2c and (e) a side view of the top of a folded carton,*

Figure 3a shows a view, on an enlarged scale, of part of a carton in accordance with the prior art;

Figure 3b shows, in still further enlarged view, a section along line III-III of Figure 3;

Figure 4a shows a view of part of a carton in accordance with the present invention;

Figure 4b shows in still further enlarged view a section along IV-IV of Figure 4a;

Figures 4c, 4d and 4e show an alternative placement of closure material beside a fold line, and its progressive alteration upon heating and closure;

Figure 5 shows in cross-section two approaching apex lines of folded channels;

Figure 6 shows a cross-section through a carton wall and a strip of deformable material in accordance with the invention, prior to folding;

Figure 7 shows a different embodiment of the cross-section of Figure 6;

Figure 8 shows a further different embodiment of the cross-section of Figure 7;

Figure 9a is a top view of a closed carton of the type shown in Figures 2a to 2e;

Figure 9b is a top view of a carton, in exaggerated form, as in Figure 9a but slightly open; Figure 9c to 9g show closures with modified configurations or modified by possessing additional component elements;

Figure 10 is a top view of an alternative emobodiment of the carton as shown in Figure 2a;

Figures 11 to 14 are perspective views of different types of carton assembly;

Figure 15 shows an additional closure mechanism for a carton as described in Figure 2a;

Figures 16 and 17 show modes of opening a closed carton of the type generally shown in Figure 2a;

Figure 18 shows an additional closure member in perspective view;

Figures 19a and 19b show the use of the additional closure member of Figure 18 shown in transverse cross section upon a carton being closed;

Figure 20 shows in perspective a carton furnished internally with two members as shown in Figure 18;

Figure 21 shows an additional top closure member; Figure 22a and 22h show the use of the additional top closure member of Figure 21 shown in transverse cross-section upon a carton being closed; and

Figure 23 shows in perspective a carton furnished internally with a member as shown in Figure 18 and at the top with a member shown in Figure 21.

Figure 24 shows a further embodiment where the closure is effected at the top of the carton,

Figure 25 shows a further modified form of the top closure of Fig 24, and

Figure 26 shows a yet further embodiment of top closure,

In Figure la a carton 1 is folded from a card blank stuck together at overlapping vertical margins where shown at 2 to give a rectangular horizontal cross-section. The upper margin 3 of the carton is defined by score lines 3a spaced a small distance below the open edge 4. Score lines 5 are spaced parallel to score lines 3 to act as fold lines for the carton top. Diagonal score lines 6, and score lines 7 at the mid point of the upper edge are located at the side faces of the carton only. Around the upper margin 3 of the carton, on the inner face, is a layer of adhesive 8. Figure la shows the carton 1 before any folding.

Figure lb shows the same carton after the initial stage of the folding process. The front and back faces fold inwardly about score lines and the sides fold outwardly also about score lines.

Figure lc shows the carton towards the end of the folding process. The top of the carton is formed by the upper parts 9, 10 of the front and back carton faces, and the folded regions 11 at the tops of the side faces, (which form at each side a triangle 12). Centrally along the top run two adhered faces corresponding to the adhesive-coated internal margins 3 of the original carton. As shown by the arrows A and B, the remaining portions are then folded over sequentially. The cross-section through I-I of Figure lc then has a configuration rather as shown in Figure Id, and the side view at the top of the carton resembles the configuration shown in Figure le.

The other, lower, end of the carton is generally identical, except that it is more customary to fold the triangular portions 12 back over the base of the carton.

Such a carton is often so configured that it can be opened by squeezing together the top of the carton (near one corner), and cutting off the end portion of the seal so as to form a pouring spout.

The prior art carton as shown in Figures la to le is to be contrasted with the carton according to the present invention which is shown similarly in Figures 2a to 2e.

Figure 2a shows the top of a carton in accordance with one embodiment of the present invention, again in the form of a sheet of card joined by over-lap at 13 and folded to a shape rectangular in horizontal cross-section. In he embodiment shown, the top of the carton consists of a first, blank, portion 14 (not provided with additional fold lines). Under this topmost portion 14 a portion 15 provided with three parallel fold lines 16, 17, 18 on each major face, and a pattern of three horizontal, two vertical and two diagonal fold lines, 19 and 20 respectively, as shown upon the minor face. This pattern is square in periphery, that is to say, around the line joining the points identified as a, b, c and d.

Figure 2b shows the carton according to the invention just after the beginning of the folding process. The central fold line 17 on each major (front or back) face is pushed inwards, and the pattern of fold lines 19, 20 and 21 on the minor (side) face is deformed as shown to present an upper and lower triangular face 22 and" internally folded sides 23.

Figure 2c shows the logical culmination of the folding process. Two triangular -wings 24 protrude from either side. The top, unfolded, portion 14 of the carton sits on top of the remaining body portion. Between these portions, as shown in cross-section in Figure 2d, the folded front and back faces approach and contact at lines 17. In accordance with the invention, and as described in more detail below, each fold line 17 carries at the inside of the carton a line of closure material. First, the two lines of closure material 25 are forced together and jointly provide a closure or seal extending along the top visible face of the carton, within the four unfolded walls constituted by portion 14.

To complete the assembly the wing portions 24 can be folded down the sides of the carton as shown in Figure 2e. This has the additional advantage of further stretching and improving the alignment of the two apex lines 17 of the folded portion so that their closure members 25 jointly ensure adequate closure of the carton.

As described more fully below, a variant of the invention consists in so folding the carton that the protruding wing portions 24 (shown externally in Figures 2b and 2σ) protrude internally into the structure. The advantages and disadvantages of this are discussed below.

Another variant is to form the external triangular portions 24 so as to protrude from the major face. This is expensive on material but has a marked visual effect.

Figure 3a and 3b show how adhesive is applied in accordance with the prior art as shown in Figures la to le. The fragmentary view shown in Figure 3a shows part of the upper periphery of the carton as shown in Figure la. Between the fold line 3a and the carton edge 4 there is a strip of adhesive material 8. Figure 3a shows the arrangement in a side view, and Figure 3b shows a section through the arrangement on an enlarged scale. It will be seen that the fold line 3a and the adhesive 8 are at all times separate, and that moreover strip 8 of adhesive, when the carton is assembled as shown progressively in Figures la to le, cooperates with a similar opposite strip to form a seal between two narrow flaps corresponding to upper margins 3 which are folded over as shown in Figure Id in the finished carton.

In contrast to this, Figures 4a and 4b show the arrangement with the present invention. They show an expanse of carton with a fold line 17 covered by an expanse of closure material 25, of a nature discussed in more detail below. When the carton is folded back about line 17, as shown in Figure 5, the closure material is presented outside the apex of the fold, and extends as a line along this apex. As the carton is progressively folded up as shown in Figures 2b and 2c the two apex lines, i.e. from the front and back faces, approach and contact, so that the closure material carried by each meets and jointly forms a closure to the underlying space of the carton. The closure extends within tabs 22/23 as a line of sealing material.

Because the closure material is located along the outside the apex of a fold line it can become somewhat attenuated as the fold progresses. Because of this it may in some cases be necessary to form, along the fold line, a reasonably high deposit of such material 25, for example as shown in Figure 6. Alternatively, and as discussed in more detail below, a thin strip of elastomeriσ material 26a can be adhered at 26 along the fold line 17^ to contact an equal and opposite strip on the approaching fold line. Alternatively again, the material at the fold line can be of a profile 27 shaped such that when the carton is folded the presented adhesive is optimised in its final shape. However, a simple adhesive layer over the fold line is also usable in the context of the present invention.

Figures 4c, 4d and 4e show a variant form of sealing expedient which can also be utilised, especially if the seal is of meltable material such as wax. In this embodiment deposits of meltable material 25 are made beside, each fold line 17, as in Fig. 4c; melted into a molten line of curved cross-section, and the fold lines approach (Fig. 4d) and coalesce over the contacting fold lines as a layer seal at Fig. 4e. In the fold-down "ears¹¹ the molten wax is spread and generally assists sealing.

This embodiment preserves the essential distinction of the present invention over the prior art since the sealing strip is not applied margin-to-margin but still seals across a vertex-to-vertex seal.

Figure 9a shows the embodiment of Figures 2a to 2e from above after the carton as shown is closed. The closure formed by the contacting apex lines 17 of the side folds and their closure material 25 is shown along the middle of the top of the closed area. Its appearance is totally different from that of the closure of the prior art. Figure 9b shows from above diagrammatically (and in a rather exaggerated manner) how such a closure opens. By distortion of the carton e. g. by pulling up of the top part 14 of the carton (as explained below) the closure member is distorted to come apart as shown. Complete opening of the closure, and restoring of the carton more or less to the shape as shown in Figure 2a can be achieved upon further manipulation. Reference has been made above to the alternative possibility, in Figure 2b of folding the triangular side portions 24 inwards, as indicated at 24a. A top view of a carton employing this possibility will be as shown in Figure 10. In many ways it is advantageous since it presents a shorter edge to edge closure 25, than that shown in Figure 9a. It is, however, more difficult to form. Also care must be taken that the seal within the folded V-shaped portions 24a is adequate.

Figures 4 to 8 show a simple fold line 17 and its approach to a second such line. However, as shown in Figs 9c to 9e, the contact may be made at a narrow apical zone. Fig. 9c shows an apical zone defined between two fold lids 17a, 17b and Fig. 9d shows the final stage of sealing of two such configurations with adhesive 25a. Fig. 9e shows a partially folded configurations with apical zones defined by three fold lines 17e, 17f, 17g, in two complementary forms, again with adhesive 25a.

Once again, the seal is still essentially vertex-to-vertex, and not margin-to-margin as in the prior art.

Figures 9f and 9g show seals with interposed sealing members of card or polymer. In Fig. 9f the member M is X-shaped in cross-section, when incorporated. After folding up it adheres and flattens to the contours of the completed seal.

In Figure 9g a folded strip member N is preadhered at 50 along beside one fold line 17h, in such a location that its free face can adhere to adhesive 25 when this is brought forward as the fold line 17h, 17j approach each other. This still essential closes, or assists in sealing, a vertex-to-vertex seal.

It will be apparent to the man skilled in the packaging trade that the sealing expedients shown can be utilised in a very wide range of packages. For example, Figure 11 shows a carton in two parts 28, 29. The lower compartment 28 of the carton has been formed with a closure as described in accordance with the present invention in Figures 2a to 2e. The upper compartment 29, of the carton has been formed by a conventional sealing closure. It is thus possible to open the top of the packet, empty the contents from the upper compartment 29, and thereafter pull the top of the carton upwards in relation to the bottom to open the second closure and release a separate and a second body of contents from the second compartment 28. This is again discussed further below.

Figure 12 shows, an alternative form of packaging in which a carton as shown in Figure 2 has a configured or decorated upper rim 30, formed from the uppermost portion 14. This gives a novel and attractive aspect at point-of-sale to an integral sealed carton.

Figure 13 can be compared with Figure 11. It shows a similar two-compartment carton but in which the lower compartment 28 is closed in accordance with the present inventionas shown in the variant embodiment described in Figure 10 i. e. where the triangular portions 24 of Figure 2b are tucked into the carton itself.

Figure 14 shows a stack of carton compartments 31, 32, 33 three units high glazed to display their differing contents. The lower two units 31, 32 are closed in accordance with the present invention and the upper unit 33 is closed by a conventional method as shown in Figures la to le.

Figure 15 shows a carton folded in accordance with the invention but in which the upper four portions, 34, 35, 36 and 37 shown merely as an upwardly protruding portion 14 in Figures 2a to 2e have been split apart at the corners so that they can be folded over the seal so as to give additional protection.

Figure 16 shows a yet further form of carton in accordance with the invention but in which only two of the upwardly extending side walls 38, 39 are present. These can be configured to suggest or promote transverse and opposed pulling, thereby to open the seal 25.

Figure 17 shows a similar carton to that of Figure 16, but in which the sides 40, 41 are configured to suggest or promote upward pulling, which has the same effect of opening apart the seal 25, 25.

The present invention, as illustrated above, depends in every aspect on the approach of an apex fold line (or narrow zone) carrying a closure material against another like apex fold line or zone. The term "closure material" is intended to cover any form of material which assists in holding the configuration together and thereby separating the closed compartment to some extent from an adjacent compartment or from the atmosphere. It can for example be material intended for one-off easy opening, such as molten wax or polymer, which when opened cannot be reclosed. It can alternatively be a reclosable material, either in the form of a tacky pressure sensitive strip of elastomer or in the form of a resilient but not self-adhesive material such as a strip of foam rubber.

It will be apparent therefore that, considering for example the two-compartment carton as shown in, e. g. Figures 11 or 13, the construction, and any closure material used can be such as to bring about the following possibilities: -

1. Mere separation. This is useful if the contained materials are relatively large particulate materials, for example lentils, dried fruit, sweets, or the like, and the packaging is merely required to keep these material separate as a marketing attraction, or to show up attractively in for example the window embodiment of Figure 14. Such mere separation could also be useful for holding a promotional premium offer separately from the contained material.

2. Powder barrier. This type of closure can be adequate to prevent dust or like fine particulate material from passing from one compartment to another. For example, floor, sugar, husks of nuts or other fruit debris can be fine material which if entering an undesired compartment can detrimentally affect the appearance of the material therein.

3. Vapour barrier. This is such as to prevent or hinder the passage of moisture vapour, at least for a time adequate for the designed shelf life, or use life, of the container. For instance, one example of this is the joint packaging of two materials, one of which requires to be crisp and the other of which requires to be moist. If they are packed together each will detrimentally affect the other. If they are packed in separate compartments of a carton separated by a closure in accordance with the invention, one can stay moist and the other crisp. Another example, which is attractive to individual users, is to package materials so that individual helpings are held in each compartment. The compartments are opened one by one, for example one each morning for a helping of cereal, and the unopened compartments stay crisp at all times.

4. Liquid barrier. A still further closure level is such as to retain liquid. Typical liquids held in cartons are milk or fruit juice. These can be held in desired portions in one compartment of a carton and, for example, cereal can be sealed off in the other compartment at any preferred liquid to solid ratio. The same technique can be used for the components of ready meals or of slimming aids, where one component is liquid and the other is solid.

5. Gas barrier. A particularly stringent requirement upon a seal is to be gas tight. This means that two components can be packaged which would otherwise suffer from cross odours or contamination, oxidation or the like. Most of the above forms of closure can be embodied either- as one off or as reclosable cartons. Reclosable cartons can be based on, for example, the approach of two strips of foam rubber or of xe-sealable low-tack adhesive at the apex lines of the folds, and can be used to hold biscuits, crisps, baby foods, coffee, tea, or any material which would suffer from unhindered exposure to air between uses. Reclosable cartons can also be used for picnic materials, packed ready to eat foods, and the like, and could be used in fast food or take away establishments to keep the flavour or odour in.

The, cartons as shown in the invention, for example the carton shown in Figure 15, can be otherwise externally wrapped so as to present a completely wrapped surface to the user. The wrapped surface could be provided with an indicating line which, if slit, liberates the two carton portions for opening and emptying.

The cartons according to the invention also lend themselves to novelty gift wrapping of toys or other objects e. g. under spring pressure such that when the box is pulled to open the seal apart the toys or the like are ejected or presented for effect.

It will be generally apparent therefore, that cartons using the closure system in accordance with the invention have different possibilities of appearance from conventional cartons, and lend themselves particularly well for novelty of point-of-sale advertising, or for joint promotions for two different materials in the same pack.

Figure 18 shows an internal structural member which can be incorporated within a carton having an end or intermediate closure as described above in accordance with the invention. As is made of folded card and comprises pairs of end tabs 101, 102 and a central section 103 comprising an narrow upper face 104 and vertical side faces 105, and acts to reinforce the closure.

The member shown in Figure 18 can be utilised as shown diagrammatically in section in Figures 19a and 19b, representing respectively an almost closed, and an opening, position for the reinforced closure, and in Figure 20 which shows a perspective view of a carton incorporating such members shown in dotted lines.

The εtrengthener shown in Figure 18 is glued by tabs 101 and 102 to either end face of a carton below the fold line 18. A like spacer, but inverted, is similarly glued above fold line 16. When the carton is open, as shown in Figure 20, the two narrow faces 104 are opposed. When the carton is folded together, as shown progressively in Figure 19b and Figure 19a, not only does the adhesive 25 on each folding line 17 come into contact but the two narrow faces 104 contact the adhesive or like layer from the top and bottom respectively and confine its potential flow so that the seal takes place within a narrow and somewhat pressurized space defined by these two faces 104 and the entering fold lines at 17.

Of course, when the carton is open the relatively small obstruction given by faces 104 is negligible. In any case, suitable folding could ensure that the faces 105 meet at a line such that passage of material in and out of the carton is essentially unobstructed.

Figure 21 shows an alternative strengthening feature for the end of a carton. It is intended to be used along with one of the two elements shown in Figure 18. As shown in Figure 21, it comprises two leaves folded together to provide a double thickness 108 with a registered hole 109 through both thicknesses, two angled portions 110 integral therewith and a narrow face 111 at the base of the angled portions. Integral tabs 112 fold down from the ends of this narrow face. In practice, this structural member is glued within one end of the closure, as shown in section in Figures 22a, 22b and in perspective in Figure 23. With particular reference to Figure 23, it will be seen that the strengthening member extends across the mouth of the carton, being adhered by the tabs 112 down a central line of each side. Figures 22b and 22a progressively show that as the top if the carton is folded in accordance with the invention the strengthening member of Figure 21 moves downwards through the same region as the two approaching fold lines 17 and their adhesive line 25.

Figures 22a, 22b and 23 also show the location of a closure as shown in Figure 18, upon which the narrow face 104 of the end closure strengthening member eventually arrives, to give a constricted sealing zone as in Figure 20.

Figure 24 shows, partly closed, the upper end of a carton equipped with a closure in accordance with the invention, that is to say with inwardly folded regions 201, 202 meeting as two vertices or apex lines and sealing along their line of contact. The sides of the carton are continued with leaves 203, 205, and the back of the carton with a leaf 205 and integral extension 206. Leaves 203, 204 are each long enough to cover, when folded inward over the sealing line, the whole top of the carton without overlap. Leaf 205 folds forward over both fold leaves 203-204, and has the same dimensions as the top of the carton. Extension 206 folds beneath the leaves 203, 204 during the coordinated folding procedure. Figure 25 shows, partly opened, the upper end of a carton equipped with a another closure in accordance with the invention. In this case only the sides possess extension flanges 207, 208 with fold lines 209, 210 on each so that the respective flap ends 207a 208a can meet as a pull-tab 211, for which purpose it is^' useful to provide a through hole 212 in the tab ends. In storage, the folded ends 213 are lightly stuck down to the carton side walls, e. g. as shown in dotted lines, and the double-thickness tab 211 can ce folded over and lightly adhered to the top surface of flap 207 or 208 also as shown in dotted lines. For use, this folded over tab is prised up and then pulled vertically to lift the folded ends 213 and open the central line seal of the invention.

Figure 26 shows in exploded view an embodiment generally similar to that of Fig. 25, although square in horizontal cross-section. The same reference numbers are therefore employed. An additional feature, for security or as a further ornamentation site is the provision of slide-on and slide-off folded band 215 to hold down the folded-over end portions 213 as well as or in addition to adhesive.

Figure 27 shows a yet further top closure embodiment partly exploded. The carton 220 is closed at the top with a seal in accordance with the invention. The ends of the seal are folded over in the usual way and stuck to the- sides of the box at 221. Over these lies an additional adhered closure strip 222, and over this a pull handle 223 is secured to the folded over ends at 221. The carton stacks as an essential flat surface, but an upward pull 226 first lifts folded portions from 221 and then pull upwards to separate the seal.

Claims

CLAIMS:

1. A carton in which a closure is formed by the approach and contact to a recipient region of the apex line or of a linear apical zone of a folded elongate indentation of generally V-shaped cross-section: where the said apex line or zone carries or borders upon a linear extent of material alterable to provide a closure member as contact is effected.

2. A carton in which a closure is formed by the approach and contact of the apex lines or of linear apical zones of two folded elongate indentations each of generally V-shaped cross-section: wherein at least one of the apex lines or linear apical zones carries or borders upon a linear extent of material alterable to provide a closure member as contact is effected.

3. A carton as claimed in claim 2 in which the closure comprises two apex fold lines.

4. A carton as claimed in claim 1,2 or 3 in which the linear extent of alterable material is a strip of material extending along the line or apical zone.

5. A carton as claimed in claim 4 in which the strip of material is a cellular elastomeric material and alters by way of resilient deformation upon closure.

6. A carton as claimed in claim 4 in which the strip of material has a sealant or putty-like consistency and alters by way of non-resilient deformation on closure.

7. A carton as claimed in claim 4 in which the strip of material is a waxy or other meltable material and is alterable by way of melting upon closure.

8. A carton as claimed in claim 4 in which the strip of material is adhesive and alterε by adhering to the opposed fold line upon closure.

9. A carton as claimed in claim 8 in which the strip of material comprises a low-tack re-sealable adhesive.

10. A carton as claimed in any one preceding claim in which the closure further comprises at least one pre-existing member located to extend across the gap upon closure.

11. A carton as claimed in claim 10 in which the pre-existing member comprises a paper or polymer strip of X-shaped or V-shaped cross-section.

12. A carton as claimed in any one preceding claim in which the closure is intermediate along the carton length to divide the carton into mutually closed or sealed regions.

13. A carton as claimed in any of claims 1 to 12 in which the closure is at one end thereof as an end closure.

14. A method of forming a carton with an intermediate closure, from a blank of foldable material, comprising the steps of:

(a) taking a blank of material having parallel side edges and having thereon four notional, indicated or pre-formed longitudinal fold lines parallel to those edges to define a face portion, and two side portions of mutually equal width such that the blank can be folded into a hollow shape of rectangular cross-section with the marginal portions overlapping and secured together,

(b) noting, marking or forming completely across the blank three transverse fold lines at right angles to the original four, longitudinal lines the outer two such transverse lines being spaced by a distance identical with that between the longitudinal fold lines defining the side portions and the central transverse line extending exactly halfway between the outer lines, (c) noting, marking or forming two diagonal fold lines between opposed corners of the square on each side portion defined by the intersections of the longitudinal lines and the outer transverse lines,

(θ) folding the blank longitudinally to its hollow shape of rectangular cross-section with the strip of alterable material inside, and securing the margins where they overlap,

15. A method of forming a carton with an end closure, from a blank of foldable material, comprising the steps of: