Paper container

Abstract

 A container (10) is formed from a piece of material having at least two layers, a first layer (12) having a first end and an opposite end, and a second layer (14) having a first end and an opposite end, the first and second layers being fixed to one another such that the respective first ends of each of the layers are spaced apart from one another to form a first step (28) and the respective second ends of each of the layers are spaced apart from one another to form a second step (26), the steps being complementary to one another and being adhered together to form a join (16,18), characterised in that the outer join line (18) is of one shape and the inner join line (16) is of a second, different, shape.

Description

[0001] This invention relates to containers, and particularly but not exclusively to containers made of card or cardboard.

[0002] Our UK patent publication number 2298855 discloses a container formed from a blank comprising a first layer and a second layer adhesively attached to one another such that a first end of one layer is spaced apart from a first end of the other layer and a second end of the first layer is spaced apart from a second end of the second layer. The two layers are thus stepped relative to one another and a container may be made by rolling the blank such that the ends are brought into abutment. The surfaces of the steps will come into contact with one another thus resulting in an overlap of the same thickness as the rest of the laminate.

[0003] A problem with cylindrical cartons with longitudinal joints is that the strains within the material forming the walls of the cartons can deform the shape of the carton locally to the join line causing it to stand proud of the rest of the exterior of the carton, a phenomenon known as "peaking". The method of construction of our above mentioned patent publication in many cases reduces peaking but may not eliminate it completely.

[0004] The present invention provides a container, and a method of making the same, improved in the above respect.

[0005] According to the present invention there is provided a container formed from a piece of material having at least two layers, a first layer having a first end and an opposite end, and a second layer having a first end and an opposite end, the first and second layers being fixed to one another such that the respective first ends of each of the layers are spaced apart from one another to form a first step and the respective second ends of each of the layers are spaced apart from one another to form a second step, the steps being complementary to one another and being adhered together to form a join, characterised in that the outer join line is of one shape and the inner join line is of a second, different, shape.

[0006] In a typical example, the outer join may be a straight line, e.g. a longitudinal join line, while the inner join line may be of a more convoluted nature, e.g. sinusoidal. The purpose of this is to spread the width of the join, and thus the load, internally of the container, so reducing peaking, while maintaining the aesthetic appearance of a straight external line. The width of join, i.e. extent of overlap, can be varied according to circumstances. For instance, with a stiffer board material the width of the join may be greater, to obviate any tendency to peak. In general, where there is more stress to be dispersed, the wider will be the join overlap.

[0007] The join lines formed from the abutment of the two edges of the respective steps may be of any shape, for example straight, curved, helical, sinusoidal, or any other regular or irregular shape, the point being that these shapes should be different so that the load on the inner join is spread differently from that of the outer. If the outer join is substantially straight it may lie at any desired angle to the base of the carton, although it is normal for such a join to be parallel to the longitudinal axis of the carton.

[0008] In order to produce a join line of non-linear shape it is desirable to form both ends of one (or both) of the layers with the desired shape in a complementary fashion so that when the opposite ends are brought together in forming a container they mesh exactly to produce the join line wanted.

[0009] Each of the first and second layers may comprise a single sheet of material or may each be a laminate formed from two or more sheets. Further sheets may be added as desired, for example an outer covering. However it is an advantage of the container of the invention that an outer covering is not normally necessary and that the sheet can be pre-printed in flat form before being formed into a carton.

[0010] Also, each sheet may be formed from the same material or two or more different materials may be used to form the sheets. The grain in the material used to form each of the sheets may be arranged to fall in substantially the same direction as the other sheet or the grain may be arranged to fall in a different direction, known as "cross graining", which adds to the strength of the resulting container.

[0011] The first and second layers may be attached to one another by any suitable means, but preferably they are adhesively attached to one another by means of a heat curable adhesive.

[0012] When the steps are complementary to one another, the join is "smooth", that is the thickness of the join is never more than two layers. However, in certain circumstances the join area may be thicker than two layers, for example three layers thick. In this case only the middle layers will meet in an abutment. This abutting join may be of any desired shape, for example straight, curved, helical, sinusoidal or any other regular or irregular shape so that the load is spread and to prevent peaking. Similarly, the outer and inner overlapping layers each terminate in an edge and these edges may be straight or any other desired shape and may be the same as each other or dissimilar

[0013] Other features of the container of the invention may be provided as shown in our above mentioned UK patent publication or indeed as known generally in the field.

[0014] The invention will be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic cross-sectional view of a container in accordance with UK patent publication 2298855;

Figure 2 is a similar view to figure 1 in accordance with the present invention;

Figure 3 is a diagrammatic plan view of first and second layers which may be used to form a first embodiment of a container in accordance with the invention;

Figure 4 illustrates the layers of figure 3 superimposed;

Figure 5 is a similar view to figure 3 of a second embodiment;

Figure 6 is a similar view to figure 4 of the second embodiment;

Figure 7 is a similar view to figure 3 of a third embodiment;

Figure 8 is a similar view to figure 4 of the third embodiment;

Figure 9 is a similar view to figure 3 of a fourth embodiment;

Figure 10 is a similar view to figure 4 of the fourth embodiment;

Figure 11 is a similar view to figure 3 of a fifth embodiment;

Figure 12 is a similar view to figure 4 of the fifth embodiment;

Figure 13 is a similar view to figure 3 of a sixth embodiment;

Figure 14 is a similar view to figure 4 of the sixth embodiment;

Figure 15 is a plan view of the container formed from the embodiment of figures 13 and 14;

Figure 16 is a diagrammatic plan view of the inner layer of a seventh embodiment of the invention;

Figure 17 is a similar view to figure 16 of the outer layer;

Figure 18 is a plan view of the layers of Figures 16 & 17 superimposed;

Figure 19 is similar view to Figure 16 of an eighth embodiment;

Figure 20 is a similar view to Figure 18 of the eighth embodiment;

Figure 21 is perspective view of the container formed from the eighth embodiment;

Figures 22 to 24 are similar view to Figures 16 to 18 of an alternative construction;

Figure 25 is a diagrammatic cross-sectional view corresponding to figure 2 in accordance with another embodiment of the present invention.

[0015] Referring to the drawings, and firstly figure 1, a tubular container generally designated 10 comprises a first layer 12 and a second layer 14. The layer 12 is the inner layer and the layer 14 is the outer layer in the finished container 10. As illustrated, the layers 12,14 are formed from a single layer of card or cardboard.

[0016] In the container both first and second ends of the first layer 12 abut at a join 16 while the first and second ends of the outer layer 14 abut at an outer join 18. The portion of the inner layer 12 between the joins 16 and 18 forms a first step 28 and the corresponding portion of the outer layer 14 forms the second step 26. The respective steps 26,28 are adhered together to form the container 10, and the join area is of the same thickness as the rest of the container wall.

[0017] As can be seen from figure 1, which is somewhat exaggerated for clarity, the container 10 forms a protrusion or "peak" 20 along the line of the inner join 16. This is due to recovery forces in the board from which the layers 12 and 14 are made acting along the line of weakness represented by the join 16.

[0018] Referring now to figure 2, and using like numerals for like parts, the outer join 18 may be a linear join as before and is preferably parallel to the longitudinal axis of the container to give a "clean" external appearance. The inner join 16', however, is spread out circumferentially over a considerable area of the wall of the container thus spreading the forces and eliminating "peaking".

[0019] The tube shown in cross-section in figure 2 may be formed from inner and outer plies (layers) as shown in figure 3. It can be seen that the outer layer or ply is a simple rectangle whereas the inner layer or ply 12 has sinusoidally curved edges 22,24. When the plies are superimposed and adhered together, as illustrated in figure 4, the container blank so-formed has straight edges 18a and 18b on the outer ply and sinusoidally curved edges of complementary shape 22, 24 on the inner ply. When the container is formed, for example by rolling the blank round an anvil and adhering the overlapping steps 26,28 together, a straight outer join 18 as shown in figure 2 will be formed parallel to the longitudinal axis of the container, and a sinusoidal inner join 16' will be formed by the complementary curved edges 22,24 meshing together, spread across a considerable portion of the circumferential surface of the walls, thereby spreading the forces tending to push the join into a "peak".

[0020] Figures 5 and 6 illustrate a second embodiment in which the outer join 18 is again a straight line join parallel to the longitudinal axis of the finished container, and in this case the inner join 22,24 is also linear but at an angle to the join 18. In the finished container this will tend to spiral round the inside of the container.

[0021] Figures 7 and 8 illustrate a third embodiment in which the outer join 18 is again linear and parallel to the longitudinal axis of the container whereas the inner join in this case is a single curved line 22, 24.

[0022] Figures 9 and 10 illustrate a fourth embodiment in which the inner layer 12 has a chevron shaped edge 22,24 and the outer layer has a straight join 18 parallel to the longitudinal axis of the container.

[0023] Figures 11 and 12 illustrate a fifth embodiment of the invention wherein the inner ply has a zig-zig shaped join 22,24 and the outer ply 14 has a straight line join parallel to the longitudinal axis of the container.

[0024] Figures 13 to 15 illustrate a sixth embodiment of the invention wherein the container produced is not regular cylindrical but is of a rounded triangular prism shape. This technique can be used anywhere where a tight radius is involved, and is not limited to the particular shape illustrated. In order to obtain this shape the inner ply 12 has score lines 30 as well as sinusoidal edges 22,24 while the outer ply 14 is rectangular in shape as before. Figure 15 illustrates the finished container and shows that the outer join 18 (formed by the abutment of the edges 18a and 18b) is again a straight line parallel to the longitudinal axis of the finished container. The inner join 22,24 is spread over the area 16' which is a considerable portion of the circumferential area of the container whereby to spread the load and prevent peaking. In addition, the score lines 30 weaken the inner ply 12 at the areas where they are formed to enable the apices of the prismatic container to be formed.

[0025] Turning now to Figures 16-18, an aperture 32 is made in the inner layer 12 and a similar aperture 34 is made in the outer layer 14. Adhesive 36 is applied around the outwardly facing portion of inner layer 12 (or the inwardly facing portion of the outer layer 14) to which is adhered a clear film material 38. When the layers are superimposed as before (Figure 18) the film 38 is sandwiched between the two layers to form, with the apertures 32,34, a window which will be in the finished container. By sandwiching the window film 38 between the inner and outer layers, the edges are hidden giving both a 'cleaner' look inside and out and in addition ensuring that a product being placed in the finished container does not snag an exposed edge leading to damage.

[0026] The film material 38 may be any suitable clear, translucent or coloured film material, such as PVC or acetate film. Where more than two layers are present, the film 38 may be sandwiched between any two. The spread join of the construction of the invention imparts enough strength and stability to the finished container to allow windows of a reasonable size to be present without overly weakening the product. Moreover the film is applied to one of the layers 'in the flat' before the container is formed, which simplifies construction.

[0027] As an alternative, illustrated in Figures 22 to 24, an aperture 34 may be made in the outer ply 14 only and printed indicia 35 positioned on the inner ply (in this case having no aperture 32) so as to show through in the finished product (Figure 24). The indicia could include product description, advertising matter, et cetera. As before, the strength of the construction of the invention allows the aperture to be used. This embodiment is particularly useful where the outer ply is difficult to print on, for instance a corrugated material.

[0028] A further development of the above concept - the strength of the join allowing apertures in the layers - is illustrated in Figures 19-21. In Figures 19 & 20 a convention is adopted in which dotted lines illustrate indicia only while solid lines (within the boundaries of a layer) indicate cut lines through the layer.

[0029] In the particular example shown, cut lines 40 are formed in the outer layer 14 for 'eyes' and cut lines 42 for 'ears'. Printed-on indicia 44 makes up the rest of a 'face'. When the layers are adhered together (Figure 20), areas 46 are left free of adhesive so that the two layers 12,14 do not adhere in these areas. Adhesive effectively covers the remaining area of the respective faces of the inner and outer layers to bond them together.

[0030] Referring now to Figure 21, when the container 10 is formed by bringing the respective edges 22, 24 together and bonding them, the areas around the cut lines 40, 42 can be lifted proud of the surface of the outer layer 14 to provide a 3-D 'feature' for the container, in this case eyes and ears of a face. As will be appreciated, this aspect is not restricted to the particular form of feature illustrated, nor is it restricted to round tubular containers as many other shapes could be employed.

[0031] Referring to Figure 25, the tubular container 10 comprises a first layer 12 and a second layer 14 as before. The layer 12 is the inner layer and the layer 14 is the outer layer in the finished container 10. As illustrated, the layers 12,14 are each formed from a single layer of card or cardboard.

[0032] It will be seen that the outer layer 14 is of greater circumferential extent than the inner layer 12 such that one end 15 abuts one end 17 of the inner layer 12 to form an abutting join 16. The respective other ends 19,21 of the layers 12 and 14 overlap the join 16 as illustrated in figure 25.

[0033] As with the previous embodiments, the shape of the join 16 may be non-linear such that there is an area 16' spread across a portion of the circumferential surface of the walls thereby spreading forces tending to push the join 16 into a "peak".

[0034] This embodiment may, as with the previous embodiments, have all the various features described, namely windows, depressions, cut-outs, non-circular shape, and the like. This form of join described herein is advantageous in certain circumstances.

[0035] While the invention has been described with, in each case, the join 18 of the outer ply being linear and parallel to the longitudinal axis of the container, it will be appreciated that it need not be so. It could be linear but not parallel to the longitudinal axis of the container, or indeed of any other shape. The important point is that the outer join is chosen with aesthetics in mind, i.e. to give a good appearance to the product, while the inner joint is made so as to increase the functional qualities of the product, namely to reduce peaking and ensure adequate strength of join.

Claims

1. A container formed from a piece of material having at least two layers, a first layer having a first end and an opposite end, and a second layer having a first end and an opposite end, the first and second layers being fixed to one another such that the respective first ends of each of the layers are spaced apart from one another to form a first step and the respective second ends of each of the layers are spaced apart from one another to form a second step, the steps being complementary to one another and being adhered together to form a join, characterised in that the outer join line is of one shape and the inner join line is of a second, different, shape.

2. A container as claimed in claim 1 in which the outer join is a straight line, e.g. a longitudinal join line, while the inner join line is of a more convoluted nature, e.g. sinusoidal.

3. A container as claimed in either of claims 1 or 2 in which the join lines formed from the abutment of the two edges of the respective steps may be of any shape, for example straight, curved, helical, sinusoidal.

4. A container as claimed in any of claims 1 to 3 in which the outer join is substantially straight and it lies at any desired angle to the base of the carton, e.g. parallel to the longitudinal axis of the carton.

5. A container as claimed in any of claims 1 to 4 in which both ends of one (or both) of the layers are formed with the desired shape in a complementary fashion so that when the opposite ends are brought together in forming a container they mesh exactly to produce the join line wanted.

6. A container as claimed in any of claims 1 to 5 in which each of the first and second layers comprises a single sheet of material or each is a laminate formed from two or more sheets.

7. A container as claimed in any of claims 1 to 6 wherein the join area is thicker than two layers, for example three layers.

Drawing