NZ618913A

NZ618913A - Bag for packing bananas

Info

Publication number: NZ618913A
Application number: NZ618913A
Authority: NZ
Inventors: Yousuke Michishita
Original assignee: Dole Japan Ltd
Priority date: 2011-05-13
Filing date: 2012-05-11
Publication date: 2014-10-31
Also published as: WO2012157579A1; JP5143928B2; JP2012236642A; AU2012256873A1

Abstract

An easy open bag for packing bananas. The bag (1) has an opening (3), a bottom side having a curved line (2), two lateral sides (9, 10) and at least one linear opening means (41) formed by a plurality of holes or slits extending from the bottom side.

Description

BAG FOR PACKAGING BANANAS Technical Field This invention relates to a bag for packaging fruits and vegetables . Specifically, this invention relates to a bag which is configured to conform to the shape and size of fruits, etc. to be packaged. In particular, this invention relates to a bananas-packaging bag having a bottom portion (a base formed of a curved line or a curved base) having a curvature corresponding to the curvature of bananas.

Background Art In the production site of bananas, bananas are generally treated according to a series of processes as follows. Namely, after the harvesting thereof, bananas are packed as a bunch consisting of several pieces of bananas. In this case, the opening of the bag is fastened, thereby shaping it as a commodity and enabling it to be shipped and sold.

As for the materials of the bag for packing bananas, transparent resin films such as polyethylene terephthalate, polypropylene, etc. are generally employed. The reason is that the bags made of these resin films are excellent in rigidity and hence suitable for transportation and, additionally, the bags can be manufactured at a low cost and the state of bananas packed therein can be easily confirmed.

With respect to the configuration of the bag for packaging bananas, it is generally shaped to have such a unique configuration that the entire state of the bag having a bunch of bananas packed therein looks nice and that the bottom portion 194913NZ_Anmd_Spec_filed_7Aug2014_EHB.doc of the bag is curved to conform to the curvature of bananas in order to omit any redundant portion of the bag to thereby save the manufacturing cost.

After finishing the packing of a bunch of bananas in the bag, the opening of bag is fastened generally by making use of a bag-sealing tape made of polypropylene film or cellophane. Since this bag-sealing tape is cheap and capable of easily and reliably fastening the opening of bag, it is generally employed as means for fastening the opening of banana-packaging bag.

However, the conventional bag for packaging bananas described above is not provided with any means for enabling consumers to easily open the bag when they desire to open it.

Even if it is desired to take out the bananas from the aforementioned bag, it is difficult, in an attempt to open the bag, to peel off the back sealing tape that is firmly adhered to the opening of bag. Furthermore, since the bag is formed of a material excellent in rigidity as explained above, it is also difficult to tear the bag. When one tries to tear the bag by force, the bananas packed therein may be unintentionally damaged. Although the bag of this kind is frequently provided with vent holes, since the material of the bag is strong, it is also difficult to expand and open the vent hole by applying a force (tensile force) to the opposite sides of the vent hole by hand.

Because of these reasons, it is required for a consumer of bananas to separately prepare a tool for opening the bag 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc on the occasion of opening the bag. Especially, for the aged and children who are powerless, there is no other way but to use scissors or a cutter on the occasion of opening the bag.

However, these tools are not necessarily available on the occasion of the opening the bag. Because of these reasons, the conventional banana-packaging bag is considerably inconvenient for consumers, etc.

With respect to the bag for packaging bananas, there are various proposals such as techniques for improving the looks of bananas on the occasion of displaying them or for enhancing the effects of enhancing the freshness of bananas (JP Patent Application Publication No. 2002-27908 and JP Patent Application Publication No. 2004-269034, for example) ; and techniques for enhancing gas permeability or for preventing bananas from being damaged (JP Patent No. 3154441, JP Patent Application Publication No. 2007-22586 and JP Utility Model No. 3014778, for example). However, there has been no proposal to provide the banana-packaging bag with opening means. Especially, no attention has been paid to opening techniques which are applicable to an ordinary banana-packaging bag formed of a most versatile material as described above.

There are several reasons why some kind of opening means is not attached to the ordinary bag for packing bananas (especially, a bunch of bananas) . First of all, since the bag for packaging bananas is special in configuration as explained above, it is rather difficult to provide the bag with any 194913NZ_Anmd_Spec_filed_7Aug2014_EHB.doc suitable opening means. Especially, since the banana- packaging bag is designed so as to omit any redundant portion as explained above, little margin is available as bananas are tightly packed in the bag. For this reason, even in the case where the bag is formed to have an excellent rigidity,, the bag is susceptible to tension. In most cases, bananas are harvested in an overseas production area and exported therefrom. In this case, since the transport of bananas from a production area to a marketing area takes a long period of time and further since the process of transport varies diversely, bananas are susceptible to vibration, shock, compression, etc. Because of these reasons, the provision of opening means to the bag may most likely invite unintended unsealing of bag or the damage of bananas.

[0011] Furthermore, since demands for bananas from consumers are relatively high among fruits and the selling price of bananas is also desired to be suppressed, the banana-packaging bag is also required to be manufactured at a low cost. This situation is also one of the reasons for not providing the bag with opening means . The employment of a resin film for forming the bag, the configuration of bag for omitting any redundant portion and the employment of a back sealing tape in general for fastening the opening of bag are all adopted for the purpose of saving the marketing price of bananas. Therefore, the provision of any opening means to the bag also should be carried out without disregarding the saving of the marketing cost of bananas. 194913NZ_Amnd_Spec_filed_7Aug2014_EHB.doc Due to the aforementioned reasons, it has been generally considered difficult to create opening means in a bag for packing bananas (especially, a bunch of bananas) which is formed of an ordinary resin film. As a matter of fact, a banana-packaging bag which is provided with opening means is not known.

Prior art publications Patent documents: Document 1: JP Patent Application Publication No. 2002-27908 Document 2: JP Patent Application Publication No. 2004-269034 Document 3: JP Patent No. 3154441 Document 4: JP Patent Application Publication No. 2007-22586 Document 5: JP Utility Model No. 3014778 Brief summary of the Invention Problems to be solved by the Invention: The present invention has been made in view of the aforementioned problems and a main object of the present invention is to provide a bag for packaging bananas, which can be easily opened by consumers, which can be hardly/scarcely damaged even if the bag is subjected to vibration or shock during the transportation thereof, and which can be manufactured at a low cost.

Means for solving the problems :

[0015] In order to solve the aforementioned problems, the present invention provides, as a first aspect, a bag for packaging bananas as described in claim 1, which comprises an 194913NZ_Amnd_Spec_filedJAug2014_EHB .doc opening; a bottom side having a curved line; lateral sides; at least one linear opening means formed of a plurality of contiguous holes or slits extending from the bottom side.

The present invention provides, as a second aspect, a bag for packaging bananas as described in claim 2, wherein the bag claimed in claim 1 is modified such that the lateral sides are constituted by a long lateral side and a short lateral side.

The present invention provides, as a third aspect, a bag for packaging bananas as described in claim 3, wherein the bag claimed in claim 2 is modified such that the bottom side is configured to have a vertex on the curved line, this vertex being located at such a location that the linear distance between the vertex and a contact point of the long lateral side with the opening becomes longer than the linear distance between said contact point and another contact point of the long lateral side with the bottom side.

The present invention provides, as a fourth aspect, a bag for packaging bananas as described in claim 4, wherein the bag claimed in claim 3 is modified such that the opening means is extended from a region of the bottom side which is confined between the contact point of the long lateral side with the bottom side and the vertex (including the vertex) .

The present invention provides,, as a fifth aspect, a bag for packaging bananas as described in claim 5, wherein the bag claimed in claim 3 or 4 is modified such that the opening means is extended from a region of the bottom side which is 194913NZ_Amnd_Spec_filed_7Aug2014_EHB .doc confined between a point of the bottom side located at least 3cm away from the contact point of the long lateral side with the bottom side and the vertex (including the vertex) .

The present invention provides, as a sixth aspect, a bag for packaging bananas as described in claim 6, wherein the bag claimed in any one of claims 1 to 5 is modified such that a portion of the bottom side is flattened and the opening means is extended from an optional point of the flattened bottom side.

The present invention provides, as a seventh aspect, a bag for packaging bananas as described in claim 7, wherein the bag claimed in any one of claims 1 to 6 is modified such that a portion of the bottom side is configured to have a tab extending in a direction opposite to the extending direction of the opening means and that the opening means is extended from an optional point of the tab.

The present invention provides, as an eighth aspect, a bag for packaging bananas as described in claim 8, wherein the bag claimed in any one of claims 1 to 7 is modified such that the opening means is extended to a length confined within a range of 3.0cm-5.0cm.

Effects of the Invention According to the present invention, it is possible to provide a banana-packaging bag which is formed of a hard-to-tear film can be easily opened by a consumer without necessitating the use of an opening tool. In spite of that, this bag can be hardly damaged even if this bag is subjected to vibration or shock during the transportation thereof. 194913NZ_Amnd_Spec_filed_7Aug2014_EHB .doc Brief description of Drawings Fig. 1 is a plan view illustrating one embodiment of the banana-packaging bag according to the present invention; Fig. 2 is a plan view illustrating inappropriate examples of the location in the installation of the opening means; Fig. 3 is a plan view illustrating another embodiment of the banana-packaging bag according to the present invention; Fig. 4 is a plan view illustrating a further embodiment of the banana-packaging bag according to the present invention; and Fig. 5 is a plan view illustrating a state (a state prior to the closing of the opening of bag) wherein bananas are packaged in the banana-packaging bag representing one embodiment of the present invention.

Best Mode for Carrying Out the Invention Next, the bag for packaging bananas according to one embodiment of the present invention will be specifically explained with reference to drawings.

Fig. 1 is a plan view illustrating one embodiment of the banana-packaging bag according to the present invention, wherein the bag is viewed from the front side thereof. For the purpose of convenience, the bag is shown in such a state that the bottom side or bottom portion 2 (hereinafter referred to as "bottom side 2") delineated by a curved line is turned upward and the opening 3 is turned downward (the same in the 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc cases of Figs. 2 to 4).

The bag 1 according to this embodiment is configured such that the shape as viewed from the front side thereof is the same as it is viewed from the back side thereof (i.e. symmetrical). However, these shapes may not necessarily be the same with each other. Further, in the drawings illustrating the following embodiments, the bag is shown, as a preferable example, as having right and left lateral sides differing in length (i.e. a long lateral side 9 and a short lateral side 10) . However, the length of these lateral sides may be made identical with each other.

In the present invention, the bottom side and the lateral sides may not necessarily be appeared as "sides" when it is viewed in a state where contents are inserted into the bag (the state of being used) as long as these sides can be recognized as being "sides" (or side-like) as the bag containing no contents therein is flattened. Although the bottom side is configured to have a curved line, the bottom side may not necessarily be constituted by only a curved line.

Namely, the bottom side may include any other linear shape other than the curved line such as a straight line. Further, the lateral sides may not necessarily be limited to a straight line.

Incidentally, with respect to the standard size of the bag (which is capable of wrapping a bunch of four to seven pieces of bananas for example) , a total longitudinal length thereof (a straight line from the vertex 7 of the bottom side 2 to the opening 3, i.e. the length of the perpendicular line as the 194913NZ_Amnd_Spec_filed_7Aug2014_EHB.doc opening 3 is considered as being the horizontal line) may be about 38 . lcm (about 15 inches) , and the length in the transverse direction thereof (the straight line extending from right to left which is represented by the opening 3 in the drawings) may be about 21.59cm (about 8.5 inches). However, the size of bag of the present invention is not restricted to these sizes. With respect to the lengths of the long lateral side 9 and of the short lateral side 10, they may be optionally determined depending on the contacting angle thereof to the curved line.

The opening 3 is an inlet portion for introducing bananas into the bag. Since the bottom side 2 of the bag 1 is configured to have a curved line conforming to the curvature of banana, the bottom of the bag 1 would take a curved configuration (curved bottom) as bananas are packaged therein .

The bag 1 is provided with opening means 41 for facilitating the opening of the bag.

The opening means is constituted by a plurality of fine holes or slits which are contiguously formed as a dotted line or a broken line. In the drawings, opening means which is constituted by contiguously aligned slits on a straight line is shown. The size and intervals of holes and slits constituting the opening means may be determined depending on the easiness of opening the bag and the strength of bag for preventing the damage of packaged contents. For example^ slits each having a length of about 3mm-5mm may be contiguously formed at an interval of about 3mm-5mm on a straight line. 194913NZ_Anmd_Spec_filed_7Aug2014_EHB .doc These holes and slits may not necessarily be contiguously formed exactly on a straight line but may be formed on a slightly curved line. Further, these holes and slits may be formed on a line perpendicular to the horizontal line of the opening 3 or may be formed on a line inclined relative to the horizontal line of the opening 3 (however, it should be taken into account the location of the opening means as described hereinafter).

It has been found out as a result of experiments that a suitable length (a total length) of the opening means is confined to the range of 3.0cm-5.0cm. If the length of the opening means is shorter than 3.0cm, it may not possible to smoothly open the bag. If the length of the opening means is longer than 5 . Oem, the bag may be prone to fracture as a tension is applied to the bag (containing bananas therein) during the transportation thereof. In view of above viewpoints, the most appropriate length of the opening means was found as being about 3.8cm (about 1.5 inches).

The opening means 41 should be formed so as to extend from an optional portion (any location) of the bottom side 2.

[0035] If the opening means is formed to extend from a location other than the bottom side 2, the following problems will be raised. For example, if the opening means is formed to extend from the short side 10 as shown by the reference number 5 in Fig. 2, the opening means may be suffered, from some sort of tension on the occasion of fastening the bag with a back sealing tape after finishing the packaging of bananas, possibly resulting in unintended opening of the opening means or 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc resulting in the fracture of the bag. Further, if the opening means is formed to extend from the long side 9 as shown by the reference number 6 in Fig. 2, the opening means may be suffered from some sort of tension on the occasion of box-packing the bags containing bananas therein, possibly resulting in the same problems as described above.

The opening means should be formed so as to extend from the bottom side 2 to the opening 3. For the purposes of not only preventing the bag from being fractured during the transportation thereof but also facilitating the opening operation of the bag by the consumers, the opening means should preferably be created in such a manner that the extending direction of the opening means is confined within the range of ±45 as measured based on the vertical line extending from the horizontal line of the opening 3.

However^ attentions should be paid to the relationships between the location for positioning the opening means and the extending angle of the opening means . As a result of experiments, it has been found out that if the opening means is formed so as to obliquely extend from a point of the bottom side which is located near to the vertex 7 but slightly biased toward the short lateral side as shown by the reference number 8 in Fig. 2, it may result in unintended opening of the opening means or result in the fracture of the bag. The reason for these incidents may be attributed to the fact that due to the relationships between the position of packed bananas and the load originated from the curvature of bananas, the opening 194913NZ_Amnd_Spec_filed_7Aug2014_EHB .doc means is prone to some sort of tension. When it is desired to provide the opening means around this position of bananas, the extending angle of the opening means should more preferably be confined so as to make it more close to the aforementioned vertical line (or just on the vertical line).

The opening means 41 should preferably be formed in such a manner that the opening means 41 formed on the front side of bag and the opening means 41 formed on the back side of bag overlap each other and extend to approximately the same extent.

In the present invention^ although there is not any particular limitation with regard to the material of the bag, resin films which are widely employed at present can be used.

These resin films are particularly characterized by very high general versatility.

A state of the bag 1 of the present invention wherein a bunch of bananas is contained in the bag is shown in Fig.

. In Fig. 5, the opening 3 is turned upward and the bottom side 2 is turned downward. Fig. 5 shows a state of the bag wherein the opening thereof is not fastened as yet. A consumer who purchased this item with the opening 3 thereof being fastened can open it in such a manner that, at first, the opposite sides of the opening means 41 are grasped using the fingers of right and left hands and then pulling force is applied in the opposite directions to the opening means 41, thereby opening the bag 1 .

According to the bag of the present invention, it is 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc possible to merchandize bananas according to the conventional processes without necessitating any additional new process.

Therefore, it is convenient to traders supplying the commodity. On the other hand, the consumers who purchased the bananas, irrespective of the aged or children, are enabled to easily open the bag by pulling the opposite sides of the opening means by hands without necessitating any complicated operation.

As shown in Fig. 1, it is preferable to form the curved line of the bottom side in such a manner that the vertex 7 can be located at such a location that the length (linear distance) between the contact point 14 of the long lateral side with the opening and the vertex 7 of the bottom side 2 becomes longer than the length of the long lateral side 10 (the linear distance between the contact point 14 and the contact point 13 of the long lateral side with the bottom side). According to this system, the curved line of the bottom side 2 is formed so as to make it expand outwards. Further, it is preferable to create the opening means 41 in such a manner that it extends from an optional location within a region of the curved line which is confined between the contact point 13 of the bottom side with the long lateral side and the vertex 7 of the bottom side 2 (Fig. 1 shows one example thereof). On the occasion of packing bananas in the bag 1, the bananas are generally introduced into the bag in such a manner that the stem portion of bananas can be located between the contact point 13 of the bottom side with the long lateral side and the vertex 7 of the 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc curved line of bottom side 2. It has been found out that when bananas are packed according to the aforementioned manner and the opening 3 is fastened, a margin can be created at this location, thereby making it possible to most effectively prevent tension from being applied to the bananas during the transport thereof. Because of this, when the opening means 41 is created at this position of the bag 1, it is possible to most effectively avoid the unintended fracture of the bag on the occasion of box-packing the bags or during the transport thereof. Incidentally, with respect to the style of positioning the stem portion of bananas, the contact point 13 may be shifted to the left side from the long lateral side in Fig. 1 (in this case, an upper portion of the long lateral side shown in Fig. 1 would be caused to curve leftwards) .

[0043] Since the vertex 7 of the bottom side 2 can be determined depending on the determination of the length of the long lateral side and the short lateral side and also depending on the determination of the angle of curved line, the location of the vertex 7 may be varied depending on the size of the bag.

However, in view of the fact that the bag would be designed so as to place the stem portion of bananas at a location between the contact point 13 of the long lateral side with the bottom side and the vertex 7 on the curved line of the bottom side 2, and, at the same time, when the size of the stem portion of bananas and the tension to be created by this stem portion are taken into account, the opening means should preferably be positioned, irrespective of the size of the bag, so as to 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc make it extend from a portion of the bottom side which is located at least about 3cm away from the contact point 13 and which does not exceed the vertex 7. Namely, it is more preferable to position the opening means in such a manner that it extend from a region of the bottom side 2 which is confined between a point of the bottom side which is located at least 3cm away from the contact point 13 and the vertex 7 (including the vertex 7) .

Fig. 3 is a plan view illustrating another embodiment of the banana-packaging bag according to the present invention. In this embodiment, a portion of the bottom side is constituted by a flat portion 11 (for the purpose of convenience, it is indicated by a double-headed arrow) as shown in Fig. 3 and opening means 42 is formed so as to extend from this flat portion 11. Preferably, this opening means 42 should be formed to extend from a central region of the flat portion Even if the various sizes of the bag are taken into account, the length of the flat portion 11 may be confined to about 0.5cm-2.0cm. In most of various sizes of the bag, a preferable length of the flat portion 11 may be confined to about 1.0cm.

The flat portion 11 should preferably be positioned within a region of the bottom side which is confined between the contact point 13 of the long lateral side with the bottom side and the vertex 7 formed on the curved line of the bottom side (the positioning of the flat portion 11 may be at the 194913NZ_Anmd_Spec_filed_7Aug2014_EHB.doc position of the vertex 7) . When the flat portion 11 is formed near to the vertex 7, part of the flat portion 11 may be extended to the short lateral side. Even in this case, it is possible to obtain the following prominent effects.

[0047] When the flat portion 11 is provided as described above, it is possible to disperse the tension to be loaded on the opening means on the occasion of merchandising bananas, during the box-packing of product or during the transport of bananas and to more effectively prevent unintended opening of the opening means or the fracture of the bag. When the flat portion 11 is positioned on a region of the bottom side which is confined between the contact point 13 of the long lateral side with the bottom side and the vertex 7 formed on the curved line of the bottom side 2 (the positioning of the flat portion 11 may be at the position of the vertex 7) and, at the same time, when the length of the flat portion 11 is confined within the aforementioned range and also when the opening means 42 is enabled to extend from a central region of the flat portion 11, it is possible to obtain especially excellent effects.

[0048] Fig. 4 is a plan view illustrating a further embodiment of the bag according to the present invention. In this embodiment, a portion of the bottom side is configured to have a tab 12 which protrudes in a direction opposite to the extending direction of the opening means. Even when various sizes of the bag are taken into account, the lateral length (lateral direction in Fig. 5) of the tab 12 should preferably be confined within a range of about 0.5cm-3 . Oem and the longest 194913NZ_Amnd_SpecJiled_7Aug201 4_EHB .doc height thereof in the protruding direction from the bottom side (vertical direction in Fig. 4) should preferably be confined within a range of about 0.5cm-1.5cm.

The opening means 43 may be formed on the bag so as to make it extend from the tab 12. Preferably, the opening means 43 should be formed so as to make it extend from a distal end portion of the tab 12.

The tab 12 should preferably be positioned within a region of the bottom side which is confined between the contact point 13 of the long lateral side with the bottom side and the vertex 7 formed on the curved line of the bottom side (the positioning of the tab 12 may be at the position of the vertex 7) .

When the tab 12 is provided as described above, it is possible to easily identify the position of the opening means of the present invention. Additionally^ by making use of the tab 12, it is possible to more easily secure a sufficient pulling force on the occasion of opening the bag. When the tab 12 is positioned within a region of the bottom side which is confined between the contact point 13 of the long lateral side with the bottom side and the vertex 7 formed on the curved line of the bottom side (the positioning of the tab 12 may be at the position of the vertex 7), when the size of the tab 12 is confined within the aforementioned range and when the opening means 43 is formed so as to make it extend from a distal end portion of the tab 12, it is possible to obtain especially excellent effects. 194913NZ_Amnd_Spec_filed_7Aug2014_EHB.doc Industrial Applicability According to the present invention, it is possible to enable consumers including frail elderly people and children to easily open a bag for packaging banana, etc. even if the bag is excellent in rigidity, without necessitating complicated operation or opening tools . In spite of that, this bag can be hardly damaged even if this bag is subjected to vibration or shock during the transportation thereof.

Therefore, it is possible to utilize a series of the conventional transporting system. Moreover, since the bag according to the present invention can be obtained at a low cost, the industrial applicability of the present invention would be very enormous.

Explanation of Symbols

[0053] 1 Bag 2 Bottom side or bottom portion having a curved line 3 Opening 41, 42, 43 Opening means , 6, 8 Inappropriate location of opening means 7 Vertex 9 Long lateral side Short lateral side 11 Flat portion 12 Tab 13 Contact point of long lateral side with bottom side 14 Contact point of long lateral side with opening 194913NZ_Amnd_Spec_filed_7Aug2014_EHB.doc

Claims

WHAT IS CLAIMED IS:

1. A bag for packaging bananas, which comprises an opening; a bottom side having a curved line; 5 lateral sides; and at least one linear opening means formed of a plurality of contiguous holes or slits extending from the bottom side.

2. The bag for packaging bananas according to claim 1, 10 wherein the lateral sides are constituted by a long lateral side and a short lateral side.

3. The bag for packaging bananas according to claim 2, wherein the bottom side is configured to have a vertex on the 15 curved line, said vertex being located at such a location that the linear distance between the vertex and a contact point of the long lateral side with the opening becomes longer than the linear distance between said contact point and another contact point of the long lateral side with the bottom side.

4. The bag for packaging bananas according to claim 3, wherein the opening means is extended from a region of the bottom side which is confined between the contact point of the long lateral side with the bottom side and the vertex. 194913NZ_Amnd_Spec_filed_7Aug201 4_EHB .doc

5. The bag for packaging bananas according to claim 3 or 4, wherein the opening means is extended from a region of the bottom side which is confined between a point of the bottom side located at least 3cm away from the contact point of the 5 long lateral side with the bottom side and the vertex.

6. The bag for packaging bananas according to any one of claims 1 to 5, wherein a portion of the bottom side is flattened and the opening means is extended from an optional point of 10 the flattened bottom side.

7. The bag for packaging bananas according to any one of claims 1 to 6, wherein a portion of the bottom side is configured to have a tab extending in a direction opposite to the extending 15 direction of the opening means and that the opening means is extended from an optional point of the tab.

8 . The bag for packaging bananas according to any one of claims 1 to 7, wherein the opening means is extended to a length 20 confined within a range of 3.0cm-5.0cm.