JP3003279U - Package - Google Patents

Abstract

(57) [Abstract] [Purpose] Excellent openability is secured without the need for special equipment such as tear tape or notches on the body seal, and the careless peeling of the package is prevented. An inexpensive and easy-to-handle package is provided. [Structure] A portion of the wrapping film 2 that covers the outer surface of the package 3 is overlapped at both ends thereof is heat-welded to form a body seal portion 7, and an extending portion of the wrapping film 2 protruding from the package 3 is formed. Upper folding part 9 formed by bending inward
In the packaging body 1 in which the side seal portion 11 is formed by heat-sealing the overlapped portions of the lower folding portion 10 and the lower folding portion 10, the non-adhesive portion 13 which is not heat-welded to the lower folding portion 10 at the end edge of the upper folding portion 9. Is formed by printing, and in the region adjacent to the non-adhesion portion 13, a weak adhesion portion 14 having a reduced adhesive strength per unit area is formed by printing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a package wrapped with a wrapping film, and in particular, a form in which the wrapping film adheres to a packaged object such that the wrapping film sticks to the packaged object. The present invention relates to a package in which one or a plurality of are packaged at the same time.

[0002]

[Prior art]

 Among the products lined up at the stores of various recent retail stores, for products with a constant shape such as magnetic tape cassettes, which are relatively small, for example, dustproofness or moistureproofing is guaranteed, and aesthetic considerations are taken into consideration. It is shipped as a package wrapped with cellophane, whose outer surface is transparent or translucent, polyethylene, polypropylene, polyvinyl chloride, or a film in which polyvinylidene chloride is coated on these, or a wrapping film. An appropriate number of products are collectively wrapped at the time of display to form a single package for bulk sale.

For such packaging with a wrapping film, a packaging method generally called shrink packaging is used. This is because when packaging a packaged product (product) with the wrapping film, after appropriately wrapping the product with the wrapping film, heating the package at an appropriate temperature according to the material of the wrapping film, By quenching, the wrapping film comes into close contact with the surface of the product due to the shrinking action of the wrapping film after the packaging is completed, and a package excellent in appearance can be obtained.

By the way, when using the packaged object wrapped with the wrapping film in this way, it is necessary to peel off the wrapping film used for the packaging, but as described above, the shrink wrapping is performed. When the wrapping film is in close contact with the surface of the product, peeling operation of the film is difficult. Therefore, conventionally, when forming a package wrapped with a wrapping film in this manner, appropriate measures are required so that the wrapping film can be easily peeled off when the packaged item is used. It

For example, in the case of a magnetic tape cassette or the like housed in a box-shaped case having a rectangular parallelepiped outer shape, the method of wrapping the packaged object with a wrapping film is not limited to that of the packaged object. Both ends of the wrapping films that are superposed on the outer surface are heat-sealed (heat-welded) to form a body seal portion, and then the extending portion of the wrapping film that protrudes from the package is bent inward. The side-sealed portion is formed by heat-sealing the portion where the upper folded portion and the lower folded portion, which are formed by swaging, are overlapped with each other to obtain a state in which the entire outer surface of the packaged object is covered with the wrapping film. The method is widespread.

As a device for making it easy to peel off the wrapping film attached to the packaged object, a so-called tear tape for opening has been used up to now, or the body seal part has been used. It is proposed that some parts are notched. In the case of using the tear tape, a narrow tape is attached to the inner surface side of the wrapping film so as to traverse the wrapping film that adheres to the packaged object, and one end of the tape is attached to the body seal. The wrapping film is torn along the tape by exposing one end of the tape by exposing the tape, and for example, the packaging body disclosed in Japanese Utility Model Laid-Open No. 332066 is disclosed. As a start, it is widely used.

Further, the notch is provided so that the notch is used as a trigger for slitting the wrapping film. Specifically, as disclosed in JP-A-5-147672. It is disclosed in Japanese Utility Model Laid-Open No. 3-43475 that a pair of notches are formed at predetermined intervals and a non-adhesive portion is formed between the notches to form a tongue-like easily peelable portion. As described above, a V-shaped cutout is formed in a direction crossing the body seal.

[0008]

[Problems to be solved by the device]

 By the way, the above-mentioned wrapping film is usually printed on the inner surface side, and if necessary, on a part of the surface side for the purpose of improving the appearance and for explaining the packaged product. Is given in advance. However, in addition to this printing step, in the case of the package using the tear tape described above, an additional processing step of laying the tear tape, which is a separate member from the wrapping film, at a fixed position on the inner surface side of the wrapping film is unnecessary. Will be needed. Further, in the case of the above-mentioned package having the cut, an extra processing step for making the cut at a predetermined position is required. Therefore, in any case, there is a problem that the dedicated equipment is increased due to the extra processing steps, the number of processing steps is increased, and the packaging cost is increased.

Further, in the packaging process (wrapping process) using the wrapping film and the transporting process of the package as described above, the extending direction of the body seal portion is usually set to the direction orthogonal to the transporting direction of the packaged object. Has been done. Therefore, if the notch is formed in a part of the body seal part, the notch may be caught in a part of the transportation equipment during a series of packaging steps or during transportation of the packaged package. There is a possibility of tearing from the notch, which may cause the inconvenient situation of peeling the package even though the opening is not intended.

Therefore, an object of the present invention is to solve the above-mentioned problems, and secures an excellent opening property without providing a tear tape or a device requiring special processing such as a notch in a body seal. At the same time, it is an object of the present invention to provide an inexpensive and easy-to-handle package that can prevent careless peeling of the package.

[0011]

[Means for Solving the Problems]

 The above object of the present invention is to cover the outer surface of a package with a wrapping film, heat seal the portions where both ends of the wrapping film are overlapped to form a body seal portion, and protrude from the package. A package in which a side-sealing portion is formed by heat-sealing a portion in which an upper folding portion and a lower folding portion, which are formed by bending an extending portion of the wrapping film inward, are heat-sealed, At least a part of each of the overlapping edges of the lower folding portion and the upper folding portion is provided with a non-adhesive portion that prevents the adhesion by heat sealing by printing. , On the side edge region adjacent to the non-adhesive portion on the edge provided with the non-adhesive portion or on the other edge overlapping the non-adhesive portion, print so that unprinted portions are lined up at appropriate intervals. Give Weakly joined portion was allowed lowering the adhesive strength per unit area by heat sealing is achieved by packaging, characterized in that provided by the.

The above object of the present invention is preferably such that the non-adhesive portion is provided at a substantially central portion of an edge of the upper folding portion, and the weak adhesive portion is adjacent to the non-adhesive portion of the upper folding portion. This is achieved by the above-mentioned package characterized by being provided in both side areas. Further, the above object of the present invention is preferably such that the dimension of the non-adhesive portion in the direction in which the upper folding portion and the lower folding portion are overlapped is set to be larger than the area where the upper folding portion and the lower folding portion actually overlap each other. It is achieved by each of the above-mentioned packages characterized in that

Further, the above-mentioned object of the present invention is characterized in that the width dimension of the edge of the non-adhesive portion, which is a handhold opening for hooking a fingertip or the like, is preferably set in a range of 10 mm or more and 50 mm or less. This is achieved by each of the above packages. Further, the above object of the present invention is more preferably achieved by each of the above packages, wherein the weakly bonded portion is formed by halftone dot printing in which a printing ink application pattern is halftone dot-shaped. .

Further, according to the above-mentioned object of the present invention, preferably, the weakly-bonded portion is formed by oblique line printing in which a coating pattern of a printing ink is an oblique line shape. To be achieved. Further, the above-mentioned object of the present invention is preferably characterized in that the weakly-bonded portion is formed by pattern printing in which portions to which printing ink is applied or portions to which printing ink is not applied are arranged at predetermined intervals. Achieved by packaging.

Further, the above-mentioned object of the present invention is achieved by each of the above-mentioned packaging bodies, characterized in that the non-adhesive portion is preferably marked with a mark that clearly indicates the non-adhesive portion. Further, the above-mentioned object of the present invention is achieved by each of the above-mentioned packages, which is preferably provided with a mark indicating the opening direction in the non-adhesive portion or in the vicinity of the non-adhesive portion.

[0016]

Embodiment

 FIG. 1 shows an embodiment of a package according to the present invention. The packaging body 1 of the present embodiment is such that the outer surface of a packaged object having a rectangular parallelepiped outer shape such as a magnetic tape cassette is shrink-wrapped with a wrapping film 2, and the packaging process (wrapping step) is as shown in FIG. The procedure is shown in FIGS. That is, first, as shown in FIG. 2, a rectangular parallelepiped shaped package body 3 is placed on the expanded wrapping film 2, and the package body 3 is placed in the longitudinal direction (arrow A in the figure). 3) by laminating both side edges 5 and 6 of the wrapping film 2 extending along the direction) on the upper surface of the packaged object 3 and heat-sealing the heat-bonded portion. As shown, the body seal portion 7 is formed (in FIG. 3, the body seal portion 7 is shown by hatching). In addition, the conveying direction of the packaged object 3 in such a lapping step or the conveying direction of the packaged object 1 after the lapping step is usually as shown by an arrow B in FIGS. It is a direction orthogonal to the extending direction of the seal portion 7.

Next, the extending portions 8 of the wrapping film 2 protruding from both sides of the package 3 are bent inward, so that the respective extending portions 8 have an upper surface as shown in FIG. The folded portion 9 and the lower folded portion 10 are formed, and further, the lower folded portion 10 and the upper folded portion 9 are sequentially folded inward and overlapped, and the overlapped portion is heat-sealed to form the upper folded portion 9 and the lower folded portion 10. By forming the side seal portion 11 (see FIG. 1) in which the portion 10 is heat-welded, the state of FIG. 1 in which the entire outer surface of the package 3 is covered with the wrapping film 2 is obtained.

In the case of the present embodiment, printing is applied to the substantially central portion of the edge of the upper folding portion 9 that covers the packaged body 3 in a close contact manner as described above, so that heat sealing is performed. The non-adhesive portion 13 that is made impossible is provided, and further, in both side regions adjacent to the non-adhesive portion 13 on the edge of the upper folding portion 9, printing is performed so that non-printed portions are arranged at appropriate intervals. By providing the heat-sealing, the weakly-bonded portion 14 whose adhesive strength per unit area is reduced by heat sealing is provided.

In FIG. 1, the non-adhesive portion 13 is shown as a cross-shaped diagonal line, and the weak adhesive portion 14 is shown as horizontal parallel lines. Both the non-adhesive part 13 and the weakly adhered part 14 are formed by printing on the inner surface side of the wrapping film 2 (the side that comes into close contact with the packaged object 3). The non-adhesive part 13 and the weakly adhered part 14 are printed together when the inner surface of the wrapping film 2 is printed with a design for improving the appearance and a description of the packaged product. Is.

Further, in the case of the present embodiment, as shown in FIG. 1, the length dimension H of the non-adhesive portion 13 in the direction in which the upper folding portion 9 and the lower folding portion 10 are overlapped is actually the upper portion. It is set to be larger than the dimension h of the region where the folded portion 9 and the lower folded portion 10 overlap. Further, in the non-adhesive portion 13, the width W of the edge of the non-adhesive portion 13 which serves as a handle opening for hooking a fingernail or the like is set within a range of 10 mm or more and 50 mm or less. This is because if the width dimension W is too small, the fingertips are unlikely to be caught, and if the width dimension W is too large, the package is likely to peel off. On the outside of each of the weakly-bonded portions 14 described above, a non-printed portion 18 having a predetermined width dimension X that is heat-sealed by heat sealing without printing is secured with a predetermined width dimension X.

Further, as described above, the weak adhesive portion 14 is formed by printing so that the non-printed portions are arranged at appropriate intervals so as to reduce the adhesive strength per unit area by heat sealing. In the case of this embodiment, as shown in FIG. 5, the weakly-bonded portion 14 is formed by pattern printing in which circular portions 16 to which the printing ink is not applied are arranged at predetermined intervals. In FIG. 5, the region on the right side of the drawing along the boundary line 17 is the non-bonded portion 13, and the region on the left side of the boundary line 17 in the drawing is the weakly bonded portion 14. In each of the areas, the shaded area is a portion coated with printing ink that makes thermal welding impossible by heat sealing. Further, the printing of the non-adhesive part 13 in the present embodiment presents a design of an isosceles triangle (or an equilateral triangle) whose bottom side is the edge side of the upper folding part 9, and clearly shows that it is a non-adhesive part. It is configured to function as a mark.

In the package 1 configured as described above, when the package is opened, a fingertip is caught on the edge of the non-adhesive portion 13 formed on the upper folding portion 9 of the side seal portion 11. Then, when the non-adhesive portion 13 is pulled in the direction of the apex of the triangle, the tensile force at that time is transmitted to the weak adhesive portion 14 adjacent to the non-adhesive portion 13 and the non-adhesive portion of the weak adhesive portion 14 is not adhered. It acts in a concentrated manner on a minute boundary area with a portion (for example, a portion as shown by an arrow (C) in FIG. 5) and easily causes a tear at the edge of the upper folding portion 9. Can be tightened.

Therefore, it is possible to easily peel off the wrapping film 2 that is closely packaged to the packaged object 3 by merely hooking and pulling the fingertip on the edge of the non-adhesive portion 13 of the side seal portion 11. become. Further, both the non-adhesive portion 13 and the weakly adhesive portion 14 can be formed by a printing process on the wrapping film 2, and the wrapping is used for the purpose of improving the appearance and explaining the packaged product. It can be formed at the same time in the printing process performed on the film 2. That is, the excellent opening property can be secured only by devising the printing process on the wrapping film 2 without using the conventional equipment such as tear tape or notch for cutting the body seal portion 7.

Therefore, for example, a special processing process for improving the unsealing property such as laying a tear tape or forming a notch in the body seal portion is not necessary, and the packaging cost can be reduced. In addition, the edge of the non-adhesive portion 13 serving as a handle opening for hooking a fingertip or the like is located on the side seal portion 11, and the extending direction of the edge of the non-adhesive portion 13 is the conveying direction of the package 1. Since the directions are substantially parallel to each other, the edge of the non-adhesive portion 13 is cut and broken by a part of the transportation equipment during a series of packaging steps or during transportation of the packaging body 1 that has been packaged. It is possible to prevent the occurrence of inconvenience such as accidental peeling of the package, and it is possible to provide a package with good handleability.

Moreover, in the present embodiment, the dimension H of the non-adhesive portion 13 in the direction in which the upper folding portion 9 and the lower folding portion 10 are overlapped is actually the upper folding portion 9 and the lower folding portion 10. Is set to be larger than the dimension h of the overlapping region, and the fingertip is hooked on the edge of the non-adhesive portion 13 so that the tear that is caused in the weak adhesive portion 14 can be quickly generated. Since it can be expanded to the outside of the overlapping portion with the lower folding portion 10, it can be greatly cut open in a short time, and thus the easiness of peeling the lapping film (opening property) is further improved.

Since both the non-adhesive part 13 and the weakly adhered part 14 are formed by printing, the contour of the non-adhesive part 13 functions as a mark that clearly indicates that the non-adhesive part 13 is a non-adhesive part. It is easy to set the shape, etc. By configuring in this way, the mechanical function necessary for opening (easiness of tearing) is secured, and at the same time the visual function to clearly indicate the opening position is exhibited. It becomes possible to improve the handleability.

In addition, in the above-described embodiment, the weak adhesive portions 14 are formed by pattern printing in which the circular portions 16 to which the printing ink is not applied are arranged at predetermined intervals. The specific method of forming 14 is not limited to that of this embodiment described above. For example, the shape of the circular portion 16 to which the printing ink is not applied in the above embodiment may be set to an arbitrary shape other than the circular shape (for example, a polygon, a flower, a star, etc.). Further, the weak adhesive portion 14 may be formed by halftone dot printing in which the application pattern of the printing ink has a halftone dot shape.

Further, as shown in another embodiment of FIG. 6, the weak adhesion portion 21 may be formed by oblique line printing in which the application pattern of the printing ink is an oblique line shape. In FIG. 6, the shaded area is a portion coated with printing ink that makes thermal welding impossible by heat sealing. Further, the shapes of the regions of the non-bonded portion 13 and the weakly bonded portion 14 are not limited to the shapes of the above embodiment. For example, as shown in FIG. 7, the area of the non-adhesive portion 22 is rectangular, and the area of the weak adhesive portion 23 is on the edge of the upper folding portion 9 on both side areas and the upper side of the non-adhesive portion 22. It may be a U-shape adjacent to the region.

Further, as shown in another embodiment of FIG. 8, when a fingertip is hooked on the handle opening at the end edge of the non-adhesive portion 24 to cause a tear, the tear is caused by the non-adhesive portion 24. The outer contour 19 of the region of the weakly bonded portion 25 may be divergent so as to easily spread in the width direction. Furthermore, as shown in another embodiment of FIG. 9, the printed patterns of the non-adhesive portion 26 and the weakly adhered portion 27 are formed in an arrow shape so as not only to clearly indicate the non-adhesive portion but also in the opening direction (FIG. In FIG. 9, it may be configured to function as a mark for pointing up).

As described above, on the weakly bonded portion of the present invention as described above, halftone dot printing in which the printing ink application pattern is a halftone dot pattern, diagonal line printing in which the printing ink application pattern is an oblique line pattern, or By appropriately selecting pattern printing, etc., in which the areas where the printing ink is applied or the areas where the printing ink is not applied are arranged at a predetermined interval, and by devising the folding pattern of the weakly adhered portion and the non-adhered portion, It is possible to obtain an excellent appearance that is harmonized with the design of the printed part for product description, and at the same time, it is possible to obtain a package with excellent handleability in which the opening position and opening direction can be easily found.

In the above-described embodiment, both the non-bonded portion and the weakly bonded portion are formed on the upper folding portion 9 side, but the non-bonded portion and the weakly bonded portion are formed on the lower folding portion 10 side. May be. Further, for example, the non-adhesive portion is formed in the upper folding portion 9, the weak adhesive portion is formed in the lower folding portion 10, and the non-adhesive portion and the weak adhesive portion are formed in different folding portions, respectively. You can However, when the non-adhesive part and the weakly adhered part are formed on the lower folding part 10, the printing on the wrapping film 2 extends to both sides, and the printing process increases accordingly. Therefore, in order to minimize the printing process, it is preferable that the non-bonded portion and the weakly bonded portion are formed on the upper folding portion 9 side.

Further, in the above-described embodiment, the weakly bonded portion is provided in both side regions adjacent to the non-bonded portion of the upper folded portion 9, whereby the handle opening portion of the edge of the non-bonded portion is provided. It was designed so that when the fingertips are hooked and pulled on, the tears will occur on both sides of the non-adhesive part, but the point is that some tears will occur, and if the tears are further opened, the wrapping film 2 can be peeled off. Well, the position where the weakly bonded portion is provided may be only on one side of the non-bonded portion.

[0033]

[Effect of device]

 According to the present invention, the outer surface of the packaged object is covered with a wrapping film, and the overlapping portions of both sides of the wrapping film are heat-sealed to form a body seal part. In a package in which a side-sealed portion is formed by heat-sealing a portion in which an upper folded portion and a lower folded portion, which are formed by bending the extending portion of the film inward, are heat-sealed. At least a part of one of the overlapping edges of the folded portion and the upper folded portion is provided with a non-adhesive portion that is made impossible by heat-sealing by printing. , On the edge provided with this non-adhesive portion or on the other edge overlapping the non-adhesive portion, the side area adjacent to the non-adhesive portion is printed so that unprinted portions are lined up at appropriate intervals. To apply Shi lowered the adhesive strength per unit area by heat sealing meth weakly bonded portions are provided me.

Therefore, when unsealing, when a fingertip is hooked on the edge of the non-adhesive portion formed in the upper folded portion of the side seal portion and pulled, the pulling force at that time is applied adjacent to the non-adhesive portion. That is propagated to the weakly bonded portion and acts concentratedly on a small boundary area between the bonded portion and the non-bonded portion in the weakly bonded portion, and easily causes a tear at the edge of the upper folded portion. You can Therefore, it is possible to easily peel off the wrapping film that is tightly packaged with the packaged object only by hooking and pulling the fingertip on the edge of the non-adhesive portion of the side seal portion. Both the non-adhesive part and the weakly adhered part can be formed by a printing process on the wrapping film, and are performed on the wrapping film for the purpose of improving the appearance and explaining the packaged product. It can be formed simultaneously in the printing process. That is, the excellent opening property can be secured only by devising the printing process on the wrapping film without using the conventional equipment such as tear tape and notches for cutting the body seal portion.

Therefore, for example, a special processing process for improving the unsealing property such as laying a tear tape or forming a notch in the body seal portion is unnecessary, and the packaging cost can be reduced. In addition, the edge of the non-adhesive portion serving as a handle opening for hooking a fingertip or the like is located on the side seal portion, and the extending direction of the edge of the non-adhesive portion is substantially parallel to the transport direction of the package. Therefore, during the series of packaging steps, or during the transportation of the packaged packaging, the edge of the non-adhesive part is caught by a part of the transportation equipment and is torn. It is also possible to prevent the occurrence of the case where the package is peeled off, and it is possible to provide a package that is easy to handle.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an appearance of a package according to an embodiment of the present invention.

FIG. 2 is an overall perspective view illustrating a wrapping process of a package according to an embodiment of the present invention.

FIG. 3 is an overall perspective view illustrating a wrapping process of a package according to an embodiment of the present invention.

FIG. 4 is an overall perspective view illustrating a wrapping process of a package according to an embodiment of the present invention.

5 is a partially enlarged view showing a state where the printing ink is applied to the weakly bonded portion of the wrapping film shown in FIG.

FIG. 6 is a partially enlarged view showing a state in which printing ink is applied to a weakly bonded portion of a wrapping film according to another embodiment of the present invention.

FIG. 7 is a front view showing an application example of a combination mode of a non-bonding part and a weakly bonding part according to another embodiment of the present invention.

FIG. 8 is a front view showing an application example of a combination mode of a non-bonding part and a weakly bonding part according to another embodiment of the present invention.

FIG. 9 is a front view showing an application example of a combination mode of a non-bonding part and a weakly bonding part according to another embodiment of the present invention.

[Explanation of symbols]

 1 Wrapping Body 2 Wrapping Film 3 Wrapped Body 5 Side Edge 6 Side Edge 7 Body Sealing Part 9 Upper Folding Part 10 Lower Folding Part 11 Side Sealing Part 13 Non-Adhesive Part 14 Weakly Adhesive Part 16 Circular Part 17 Boundary Line 18 Non-Printing Department

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B65D 85/575

Claims (9)

[Scope of utility model registration request] 1. A wrapping film which covers the outer surface of an object to be wrapped with a wrapping film, heat-seals parts where both ends of the wrapping film are overlapped to form a body seal portion, and which extends from the object to be wrapped. Of the upper folded portion and the lower folded portion, which are formed by bending the extending portion of the lower folded portion inward, are heat-sealed to form a side seal portion. Further, a non-adhesive portion that is made impossible to be adhered by heat sealing by printing is provided in a part of at least one of the respective overlapping edges of the upper folding portion and the non-adhesive portion. By printing on the side region adjacent to the non-adhesive portion on the edge provided with or on the other edge overlapping the non-adhesive portion, printing is performed so that unprinted portions are arranged at appropriate intervals. Package, characterized in that the weakly joined portion was allowed lowering the adhesive strength per unit area by Toshiru is provided. 2. The non-adhesive portion is provided at a substantially central portion of an edge of the upper folding portion, and the weakly adhering portions are provided in both side regions adjacent to the non-adhesive portion of the upper folding portion. The package according to claim 1, wherein: 3. The dimension of the non-adhesive portion in the direction in which the upper folding portion and the lower folding portion overlap is set to be larger than the area in which the upper folding portion and the lower folding portion actually overlap. The packaging body according to claim 1 or 2. 4. The width dimension of the edge of the non-adhesive portion, which is a handle opening for hooking a fingertip or the like, is set in a range of 10 mm or more and 50 mm or less. The package according to item 1. 5. The weak adhesion portion is formed by halftone dot printing in which a printing ink application pattern has a halftone dot shape. Packaging. 6. The package according to claim 1, wherein the weakly adhered portion is formed by oblique line printing in which a printing ink application pattern is an oblique line shape. . 7. The weak adhesion portion is formed by pattern printing in which portions to which printing ink is applied or portions to which printing ink is not applied are arranged at a predetermined interval. The package according to any one of items. 8. The package according to claim 1, wherein the non-adhesive portion is provided with a mark that clearly indicates the non-adhesive portion. 9. The non-adhesive portion or in the vicinity of the non-adhesive portion,
The package according to any one of claims 1 to 8, which is provided with a mark indicating an opening direction.