EP0778210A1

EP0778210A1 - Method of manufacturing a liquid-tight box

Info

Publication number: EP0778210A1
Application number: EP96203445A
Authority: EP
Inventors: Johannes Fredericus Spronk
Original assignee: Crystal BV
Current assignee: Crystal BV
Priority date: 1995-12-07
Filing date: 1996-12-05
Publication date: 1997-06-11
Also published as: NL1001844C2

Abstract

Method for manufacturing a cardboard box (D) through folding and adhesion, wherein a blank (P) is cut or die-cut from cardboard and folding lines are provided in the blank which bound the different blank panels, characterized in that for the blank use is made of a type of cardboard whose surface is impermeable to water, liquid oils or like liquid products; wherein, after the blank has been cut out and the folding lines have been provided, a strip (S) of paper or film impermeable to water, liquid oils or like liquid products is arranged on the blank at the location of all cut edges (9,10,11) facing the box interior in the folded condition; wherein the strip, at least at the location of those cut edges, extends outside the circumferential edge of the blank surface as defined by the cut edges in question, in such a manner that all cut edges facing the box interior in the folded condition are screened from the box interior by the strip arranged thereon.

Description

This invention relates to a method according to the preamble of claim 1. Such a box is known, for instance, for packaging milk, water and like liquid foods, but also for packaging liquid detergents, oils and like liquid products.
The known boxes have as a chief drawback that they are not hundred-percent recyclable. After being partly folded up, the boxes are provided with an internal coating, whereafter the box is filled with the liquid to be packaged and the top is closed off by pressing two opposite sidewalls against each other and joining them together by sealing or adhesion, in such a manner that a roof-shaped top is obtained. Such a manner of closing the top is necessary to prevent the circumferential edges of the blank, formed by the cutting or die-cutting operation, from eventually facing the box interior. This prevents the cut edges, which are not provided with a liquid-tight coating, from coming into contact with liquid, which would lead to leakage as a result of moisture penetrating the cardboard.
However, a drawback of the coating applied in partly folded condition is that, as a consequence, the package is no longer completely recyclable, since the coating cannot simply be separated from the cardboard of the blank, so that the box cannot be processed as normal waste paper.
The object of the invention is to provide a method for manufacturing a box without the above-mentioned drawback.
To that effect, the method is characterized by the features of claim 1.
By virtue of the feature that all cut or die-cut edges facing the box interior which are susceptible of moisture penetration are covered by a strip of paper or film which is impermeable to water, liquid oils or like liquid products, a completely liquid-tight box is obtained without requiring the inside of the box to be coated in partly folded condition. When the strip is made of recyclable paper, a hundred-percent recyclable liquid-tight package is obtained.
The invention also relates to a box which has been obtained using the method according to the invention.
Further elaborations of the invention are described in the dependent claims and will be further clarified on the basis of a number of exemplary embodiments, with reference to the drawing.

Fig. 1 shows a perspective view of a first exemplary embodiment of a box whose end panels are in the intermediate position;
Fig. 2 shows a perspective view of a second exemplary embodiment of a box whose end panels are in the intermediate position;
Fig. 3 shows a perspective view of a third exemplary embodiment of a box whose end panels are in the intermediate position;
Fig. 4 shows a top plan view of a fourth exemplary embodiment of a box whose end panels are in the intermediate position;
Fig. 5 shows an exemplary embodiment of a blank for a box according to the invention; and
Fig. 6 shows the manner in which a strip has been folded on the connecting panel around the free edge thereof.

The method for manufacturing a cardboard box D through folding and adhesion will be described with reference to a few drawings in which a blank P or box D is represented.
For manufacturing a cardboard box, a blank P is cut or die-cut from cardboard. Simultaneously or subsequently, folding lines are provided in the blank P, which define the different blank panels.
According to the invention, for the blank P, use is made of a type of cardboard whose surface is impermeable to water, liquid oils or like liquid products. After the blank P has been cut out and the folding lines have been provided, a strip S of paper or film impermeable to water, liquid oils, or like liquid products is arranged on the blank P at all cut edges 9, 10, 11 proximal to the box interior in the folded condition of the box. At least at the location of those cut edges 9, 10, 11, the strip S1, S2 extends outside the circumferential edge of the blank surface as defined by the cut edges 9, 10, 11 in question, in such a manner that all cut edges 9, 10, 11 proximal to the box interior in the folded condition are screened from the box interior by the strip S1, S2 fitted thereon.
As is clearly depicted in Fig. 5, the blank P is provided with a number of sidewall panels 1, 2, 3, 4 and a number of end wall panels 5, 6, 7, 8, forming a bottom or a top of the box D, and each being connected through an end wall folding line 12, 13, 14, 15 to a corresponding sidewall panel 1, 2, 3, 4. Adjacent at least two end walls 5, 7, associated with sidewalls 1, 3 located opposite each other in the folded condition of the box, the strip S1 projects beyond the free edge 9, 10 of the end wall 5, 7, which is located opposite the end wall folding line 12, 14 of the corresponding panel 5, 7. When folding up the box, the two end walls 5, 7 are the first to be folded inwards into their eventual position perpendicular to the sidewall panels. The other sidewall panels 6, 8 are temporarily folded outwards. The box is then in the intermediate position represented in Figs. 1-4.
In the exemplary embodiment of Fig. 3, the free edges S5, S7 of the strip S1 are directly connected to each other.
In the exemplary embodiment of Figs. 2 and 4, the free edges S5, S7 are indirectly connected to each other through a closing strip A.
In all exemplary embodiments shown, the strip S1 is completely connected with the two end wall panels 5, 7 folded inwards in the intermediate position mentioned. To the other end walls 6, 8 the strip S1 is connected in such a manner that in the intermediate position mentioned, the free edges S5, S7 of the strip S1, which are to be connected to each other either directly or indirectly through the closing strip A, are under tension such that a press-on force can be exerted on them which is necessary to effect a good glued or sealed joint. As is clearly visible in Fig. 5, this is effected by not providing the end wall panels 6 and 8 which are folded outwards in the intermediate position, with glue at the location of the hatched triangular portions or not connecting them to the strip S1 by means of a sealing operation. The triangular portions of the strip S1 not connected with the end walls include an angle of about 45° with the end wall folding lines 13, 15, so that the intermediate positions represented in Figs. 1-3 can be assumed.
As depicted in Figs. 1 and 2, the closing strip A can be an integral part of the strip S1 and, after the end walls 5, 6, 7, 8 have been set in the intermediate position, be folded back so as to be connected with the free edges S5, S7 of the strip S1 which extend parallel to the free edges 9, 10 of the inwardly folded end wall panels 5, 7 and with the strip portions connected with or lying against the other end wall panels 6, 8. An advantage of such a design is that the closing strip A is always properly positioned with respect to the strip S1. However, a minor drawback is that rather much strip material is lost when cutting out such a strip S1 with an integral closing strip formed thereon.
In order to meet this drawback, it is also possible for the closing strip A to be a loose part which, after the end walls 5, 6, 7, 8 have been brought in the intermediate position, is arranged by a separate closing strip dispensing device, so as to be connected with the free edges S5, S6 of the strip S1 which extend parallel to the free edges 9, 10 of the inwardly folded end wall panels 5, 7 and with the strip portions connected with or lying against the other end wall panels 6, 8.
Preferably, the closing strip A has a width less than the distance between the free edge 9 and 10 in the intermediate position of the box. Of course, the width should be greater than the distance between the free edges S5, S7 of the strip S1 in the intermediate position of the box. Thus the possibility of moisture seeping through to the free cut edges 9, 10 is absolutely precluded.
For manufacturing a box which has the appearance of a conventional milk carton and yet has the advantages according to the invention, end wall panels 5, 6, 7, 8 should constitute the bottom of a liquid package. The bottom is then closed off in the manner of the invention. In doing so, it is optionally possible, for the purpose of connecting with each other the edges S5, S7 of the strip S1, which are free in this intermediate position, either directly or indirectly through a closing strip A, to utilize a retainer block temporarily accommodated in the box interior. This block can then take up the pressure required for effecting an adhesive or sealed joint. Then the package is filled with the liquid to be packaged and the top of the package is closed in a conventional manner by pressing two opposite sidewalls against each other and joining them through sealing or adhesion, so that a saddle roof-shaped top is obtained, as is usual in the known milk cartons.
The advantage of such a manner of manufacturing a milk carton is that it can be carried out on the apparatus already in use, with a minimal number of adaptations to the existing production lines.
Of course, it is also possible for both the top and the bottom of the box to be closed according to the method of the invention, whereby, after the closure of the bottom of the box, the box is filled with the liquid to be packaged and thereafter the top of the box is closed in the manner as described in claim 3, that is, without requiring the use of a retainer block, which, for that matter, is no longer possible because the box is filled with liquid.
As is clearly depicted in Figs. 5 and 6, the blank is also provided with a connecting panel 16 by means of which the sidewalls 1, 4 are connected with each other. Before the sidewalls 1, 4 are joined together, a second strip S2 is arranged on the connecting panel 16, which strip, when the sidewalls are being joined together, is folded over the free edge 11 of the connecting panel 16 proximal to the box interior, and is connected with the connecting panel 16 through adhesion or sealing. The resultant achievement is that also the free edge 11 of the connecting panel 16 facing the box interior is not exposed to liquid.
In order to obtain optimum recyclability of the box, preferably both the blank P and the strips S1, S2 are made from recyclable cardboard or paper impermeable to water, liquid oils or like liquid products.
For reasons of production technique, it is particularly favourable when for effecting the connections between the strips S1, S2 and the blank P, between the strips S1, S2, and between the blank panels, use is made of so-called A-B adhesives, with a first part comprising an A layer and a second part, to be connected to the first part, comprising a B layer. The two layers as such do not possess any adhesive power but when the A layer and the B layer are pressed against each other, a fixed connection is formed very quickly.
The boxes which are depicted and which are obtained through the method are naturally part of the subject matter of the invention.
It will be clear that the invention is not limited to the exemplary embodiments described but that various modifications are possible within the scope of the invention.

Claims

A method for manufacturing a cardboard box (D) through folding and adhesion, wherein a blank (P) is cut or die-cut from cardboard, and folding lines are provided in the blank (P) which bound the different blank panels, characterized in that for the blank (P) use is made of a type of cardboard whose surface is impermeable to water, liquid oils or like liquid products; wherein, after the blank (P) has been cut out and the folding lines have been provided, a strip (S) of film or paper which is impermeable to water, liquid oils or like liquid products is arranged on the blank (P) at the location of all cut edges (9, 10, 11) proximal to the box interior in the folded condition; wherein the strip (S1, S2), at least at the location of those cut edges, extends outside the circumferential edge (9, 10, 11) of the blank surface as defined by the cut edges in question, in such a manner that all cut edges (9, 10, 11) proximal to the box interior in the folded condition are screened from the box interior by the strip (S1, S2) arranged thereon.
A method according to claim 1, characterized in that the blank is provided with a number of sidewall panels (1, 2, 3, 4) and a number of end wall panels (5, 6, 7, 8) forming a bottom or a top of the box (D) and each being connected with an associated sidewall panel (1, 2, 3, 4) through an end wall folding line (12, 13, 14, 15), wherein adjacent at least two end walls (5, 7) associated with two sidewalls (1, 3) located opposite each other in the folded condition, the strip (S1) projects beyond the free edge (9, 10) of the end wall (5, 7), located opposite the end wall folding line (12, 14) of the respective panel (5, 7), these two end walls (5, 7) being the first to be folded inwards into their eventual position perpendicular to the sidewall panels, while the other end wall panels (6, 8) are temporarily folded outwards, whereafter in this intermediate position the free edges (S5, S7) of the strip (S1) are connected directly to each other or are connected indirectly to each other through a closing strip (A).
A method according to claim 2, characterized in that the strip (S1) is completely connected with the two end wall panels (5, 7) folded inwards in said intermediate position and is connected in part with the other end walls (6, 8), in such a manner that in said intermediate position the free edges (S5, S7) of the strip (S1), which are to be connected to each other either directly or indirectly through the closing strip (A), are under tension such that a press-on force can be exerted on them which is necessary to effect a good glued or sealed joint.
A method according to claim 2 or 3, characterized in that the closing strip (A) is an integral part of the strip (S1) and, after the end walls (5, 6, 7, 8) have been set in the intermediate position, is folded back so as to be connected with the free edges (S5, S7) of the strip (S1) which extend parallel to said free edges (9, 10) of the inwardly folded end wall panels (5, 7) and with the strip portions connected with or lying against the other end wall panels (6, 8).
A method according to claim 2 or 3, characterized in that the closing strip (A) is a loose part which, after the end walls (5, 6, 7, 8) have been brought in the intermediate position, is arranged by a separate closing strip dispensing device, so as to be connected with the free edges (S5, S6) of the strip (S1) which extend parallel to said free edges (9, 10) of the inwardly folded end wall panels (5, 7) and with the strip portions connected with or lying against the other end wall panels (6, 8).
A method according to any one of claims 2-5, characterized in that said end wall panels (5, 6, 7, 8) form the bottom of a liquid package, wherein first the bottom is closed off in the manner according to any one of claims 2-5, while optionally, for the purpose of connecting with each other the edges (S5, S7) of the strip (S1) which are free in this intermediate position, either directly or indirectly through a closing strip (A), use is made of a retainer block temporarily accommodated in the box interior, which block can take up the pressure required for effecting an adhesive or sealed joint; wherein thereafter the package is filled with the liquid to be packaged and the top of the package is closed in a conventional manner by pressing two opposite sidewalls against each other and joining them through sealing or adhesion, so that a saddle roof-shaped top is obtained, as is customary in, for instance, milk cartons.
A method according to any one of claims 2-5, characterized in that both the top and the bottom of the box are closed according to the method of the invention, whereby, after the closure of the bottom of the box, the box is filled with the liquid to be packaged and thereafter the top of the box is closed in the manner according to claim 3.
A method according to any one of the preceding claims, characterized in that the blank is further provided with a connecting panel (16) by means of which the sidewalls (1, 4) are connected with each other, wherein, before the sidewalls (1, 4) are joined together, a second strip (S2) is arranged on the connecting panel (16), which second strip (S2), when the sidewalls are being joined together, is folded over the free edge (11) of the connecting panel (16) facing the box interior, and is connected with the connecting panel (16) through adhesion or sealing.
A method according to at least one of the preceding claims, characterized in that both the blank (P) and said strips (S1, S2) are made from recyclable cardboard or paper impermeable to water, liquid oils or like liquid products.
A method according to claim 9, characterized in that, for effecting the connections between the strips (S1, S2) and the blank (P), between the strips (S1, S2), and between the blank panels, use is made of so-called A-B adhesives, with a first part comprising an A layer and a second part, to be connected to the first part, comprising a B layer, with neither layer as such possessing any adhesive power, while the A layer and the B layer, when pressed against each other, very quickly form a fixed connection.
A box obtained with a method according to any one of the preceding claims.