GB2276147A - Tear strips for opening boxes - Google Patents

Abstract

A strip for tearing on a length of board material used in the construction of containers or boxes is formed by applying a strip of adhesive tape 44 to the board and forming perforations 50, 52 in association with the tape in such a way that the tape is located between two spaced rows of perforations. The rows of perforations may be offset with respect to each other. <IMAGE>

Description

OPENING BOXES This invention relates to boxes and containers, for example made of corrugated fibreboard, in which provision is made for opening the box by means of tearing a strip of the material of the box. An example of the application of the invention is to display boxes of the kind in which after opening the box, a part of the box can be used for display purposes. The invention may well be applicable to boxes incorporating removable strips for opening purposes generally.

Prior proposals in relation to display boxes include the provision of a band of tape adhered to the inside surface of the box and provided with a row of perforations located centrally of the tape, these perforations enabling opening of the box by manually ripping the box using the tape as an aid thereto, and commencing at a location on the box where means is provided to enable an initial hand-hold to be obtained.

The ripping process enables the box to be divided along the line of perforations, and if carried out carefully a neat break line is obtained so that the portion of the box to be used for display purposes is neat and presentable.

Shortcomings of this prior proposal include the fact that the perforations are a source of mechanical weakness in the box, leading to difficulties when the box is highly stressed during transport or loading prior to opening. A further shortcoming is that tolerances and other variables arising during manufacture can lead to the misalignment of the perforation-provision machinery with respect to the tape, whereby the perforations are not located centrally of the tape, and may even miss it altogether, whereby the tape fails to provide a proper ripping function, and/or is rendered inoperative.

An object of the present invention is to provide improvements in relation to one or more of the above matters, or improvements generally in relation to such containers.

According to the invention there is provided a method of providing a strip for tearing on a length of board material for use in the construction of containers or boxes. The invention also provides a length of board material produced by such a method, a blank for the construction of a box or container made from such a board material, and a box or container formed from the blank.

According to one aspect of the invention the method of providing a strip for tearing comprises applying a strip of adhesive tape to the length of board material, forming perforations in association with the tape, and the method is characterised by carrying out the step of forming the perforations in such a manner that two spaced rows of perforations are formed, and the step of applying the strip of adhesive tape is carried out by so-applying the tape that it is located between the spaced rows of perforations in the product of the method.

In a preferred embodiment, the formation of the rows of perforations and the application of the tape is carried out substantially simultaneously and atthe same location during the board manufacturing process. The provision of the strip for tearing is carried out on a web of board material before the web is cut into blanks, and thus likewise before these blanks are used for the construction of boxes or containers.

A second aspect of the invention concerns a method of providing a strip for tearing on a length of board material in which a strip of adhesive tape is applied and perforations are formed in association with the tape. According to this aspect of the invention there is provided the improvement of forming said perforations simultaneously with the application of the tape, and at the same location, whereby correct alignment of the perforations and the tape is thereby assured.

The invention also provides a web or length of board material having applied thereto a strip of adhesive tape and associated perforations as defined in the preceding paragraphs.

In the preferred embodiment, the step of providing two spaced rows of perforations has the result that the "land" of board material between the rows of perforations enhances the strength of the board material before the stage at which the strip for tearing is torn, thereby reducing the problem of weakness which has been inherent in the prior art proposal mentioned above. Moreover, by providing two lines of perforations, the tearing function is enhanced and there is no longer a need to provide the individual perforations at closely spaced intervals in order to have an effective tear function. Thus, depending on the degree of spacing of the perforations, the strength function can be further enhanced.

Likewise in the preferred embodiment, the provision of the strip of adhesive tape applied to the board material between the spaced rows of perforations serves to enhance the tearing function by reducing the tendency for ineffective and/or uneven or untidy tearing to occur. The tape is adhered to a defined land of material between the perforation lines, and this leads to a positive and direct tearing action.

A further feature of the preferred embodiment provides for the perforations of the two spaced lines of perforations to be staggered or offset with respect to each other. In this way, the strength function of the lands of material extending between the perforations and into the zone between the lines thereof, is enhanced. This effect is maximised where there is zero overlap of the perforations of the two lines.

However, depending upon the strength requirements of the product, the overlap may increase to 50%, as shown in the drawings hereof, or indeed up to 100% overlap, for certain applications, as also shown in the drawings.

In the preferred embodiment of the invention also, the strip of adhesive tape is applied to the board material simultaneously with the formation of the perforations, and at that same location. In this way, accuracy of registration between the tape and perforations is achieved, as compared with prior proposals in which the application of tape and yformation of perforations have been performed separately whereby misalignment can occur between the two locations. In the preferred embodiment, the tape is applied to the board in association with a perforation wheel having two spaced rows of teeth to form the perforations, with the tape passing between these rows, and being applied to the board substantially simultaneously with the operation of perforation it. In this way, accuracy of alignment as between the tape and the perforations is ensured.

Considering now some more detailed aspects of the preferred embodiment, this relates to the production of a blank of corrugated fibreboard incorporating tearing means, the blank being intended for eventual conversion into a finished pack.

Corrugated fibreboard is produced on a corrugating machine by joining three or more various types of paper which have been conditioned by exposure to heat and steam. From this board will be cut a blank at the required size for eventual conversion into a finished pack, box or carton.

However, prior to such cutting on the corrugating machine, the tearing means is provided on the board. Positioning of the tearing means on the board is subject to the requirements of the finished pack. As the tape of the tearing means is guided into position on the board, namely onto the surface thereof which will be the inner surface of the pack, it self-adheres.

At this instant perforations are formed at each side of the tape. The perforations are staggered with respect to each other so that a perforation of one row is aligned with an uncut section on the row opposite.

The cut-to-size piece of board complete with the tape and perforations is processed into the pack blank. At this stage a start/finish aperture is also positioned which can be at any required location along the length of the tearing means or zone.

The blank is then either glued or stitched or stapled to produce a finished carton.

The user loads and seals the carton in the conventional way. The goods inside are displayed by opening the carton using the tear strip. This is done by manually grasping one of the tabs at the start/finish aperture and tearing in an "up and away" direction around the perimeter of the carton. It may be necessary to use both of the tabs, one after the other.

When the tearing action has been performed all round the pack, the top half of the carton can be lifted away and discarded with the tape. The lower portion of the carton remains with the goods as originally positioned, and is now useable as a tray for display.

Advantages provided by the preferred embodiment include the improved tearing action. The tape is able to rip through the corrugated board without breaking, and the two rows of perforations guide the ripping action. The lower row of perforations gives a clean straight edge which is important for display purposes.

The location of the tape between the two rows of perforations is achieved by registering the tape in this position at the board making stage, thus avoiding the positioning errors arising from carrying out this operation at the stage of forming the carton.

The staggering of the perforations improves pack strength so that, dependent on the degree of stagger and perforation spacing, a strength comparable to that of a pack not having a tear strip is achieved.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which Fig 1 shows a plan view of a carton blank; Fig 2 shows the process of perforating a web of board material and simultaneously applying a tear tape; Fig 3 shows an elevation view of a perforating wheel seen in Fig 2; Fig 4 shows an isometric view of a carton incorporating a tear strip produced in accordance with matters shown in Figs 1 to 3; Fig 5 shows the carton of Fig 4 after opening; and Figs 6, 7 and 8 illustrate varying degrees of overlap and stagger between the perforations of two rows of perforations for use in a method according to the invention.

As shown in the drawings, a carton blank 10 is produced from a web 12 of fibreboard and comprises panels 14, 16, 18 and 20 each having corresponding flaps 22, 24, 26 and 28.

Fold lines 30, 32 and 34 separate the panels. Further fold lines 36, 38 separate the flaps from the panels. A joint panel 40 is provided.

It is to be understood that the carton design shown in Fig 1 is provided merely by way of example and the invention is applicable to almost any form of carton, box or container using a tearable or ripable board material.

Turning now to the details of the construction of a tear strip 42 seen in Fig 1, it can be seen from the enlarged portion 1A of Fig 1 that the strip for tearing 42 comprises a band or strip of adhesive tape 44 located between two rows 46, 48 of perforations 50 and 52 respectively.

Tape 44 is applied to web 12 simultaneously with the formation of the perforations 50 and 52, as shown in Fig 2.

This is achieved by means of a perforation wheel 54 having two rows 56, 58 of teeth 60, spaced apart by a drum 62 so that a space 64 is provided to receive tape 44 for application to web 12 at a location 66, substantially simultaneously with the action of teeth 60 to form the perforations.

As shown in Fig 4, blank 10 is formed into a carton 68.

A tear commencement opening 70 is formed in carton 68 and tear strip 42 to enable tearing to be started quickly and easily.

Opening 70 is stamped in blank 10 at the same time that the blank itself is stamped out of web 12. Fig 4 shows the strip for tearing partially removed in an upward tearing action leaving a clean and well-defined straight edge 72 in the lower portion 74 of carton 68, for display purposes.

Fig 5 shows the upper portion 76 of carton 68 removed from the lower portion 74, whereby the latter can be used for goods - display purposes.

Figs 6, 7 and 8 illustrate somewhat diagrammatically varying degrees of stagger and overlap of the perforations 50 and 52. In Fig 6, there is substantially no overlap at all between the perforations, as viewed in a direction at right angles to the lengthwise axis of each row of perforations.

In Fig 7, there is a 25% overlap at each end of each perforation, and thus a 50% overlap overall. In the arrangement of Fig 8, there is substantially 100% overlap.

Claims (16)

CLAIMS ;

1 A method of providing a strip for tearing on a web, or length of board material for use in the constructions of containers or boxes comprising applying a strip of adhesive tape to a length of board material, and forming perforations in said board material in association with the tape; characterised by the step of forming the perforations in said board material in such a manner that two spaced rows of perforations are formed, and that the step of applying the strip of adhesive tape is carried out by so-applying the tape that it is located between the spaced rows of perforations.

2 A method according to claim 1 wherein the steps of formation of the rows of perforations and the application of the tape are carried out substantially simultaneously and at the same location during the board manufacturing process.

3 A method according to claim 1 or claim 2 wherein the step of providing the strip for tearing is carried out on a web of board material before the web is cut into blanks.

4 A method according to any one of the preceding claims wherein the tape is applied to the board in association with a perforation reel having two spaced rows of teeth to form the perforations, with the tape passing between these rows, and being applied to the board substantially simultaneously with the operation of perforating it.

5 A method according to any one of the preceding claims characterised by the further step of providing a tear commencement opening positioned at any location along the length of the tearing means.

6 A method according to any one of the preceding claims characterised by the further step of cutting the web to form at least one blank for the construction of a box or container.

7 A method according to claim 6 wherein a tear commencement opening is stamped at the same time that the blank is stamped out of the web.

8 A method according to claim 6 or claim 7 characterised by the further step of gluing or stitching or stapling the blank to a produce box or container.

9 A web or length of board material having applied thereto a strip of adhesive tape and associated perforations characterised in that the board material is provided with two spaced rows of perforations and the tape is located between said two spaced rows.

10 A web according to claim 9 wherein the perforations of the two spaced rows of perforations are staggered or offset with respect to each other.

11 A web according to claim 9 or claim 10 wherein there is zero overlap of the perforations of the two rows.

12 A web according to any one of claims 9 to 11 wherein the web is further provided with a tear commencement opening at any location along the length of the tearing means.

13 A blank for the construction of a box or container produced from a web according to any one of claims 9 to 12.

14 A box or container when constructed from a blank according to claim 13.

15 A method of providing a strip for tearing on a length of board material substantially as described hereinbefore with reference to the drawings.

16 A web or length of board material substantially as hereinbefore described with reference to the drawings.