Method for wrapping up a cassette case in thin film

Abstract: There is provided a wrapping method in which a wrapped product is wrapped by a sheath film and partly-overlapped portions of the sheath film are melt-bonded by heat to heat-seal the sheath film. When the user opens the sheath film, the user can tear the same with ease. A heat sealing area of the sheath film (1) is printed by a halftone printing portion (10) to uniformly reduce the whole bonding area, thereby decreasing the bonding strength.

Description: BACKGROUND OF THE INVENTION Field of the Invention: The present invention generally relates to a wrapping film that can tightly wrap a cassette case or the like in which a tape cassette for a video tape recorder or audio tape recorder is accommodated and, more particularly, to a wrapping film that the user can open with ease. Description of the Prior Art: It is customary that cassette cases are wrapped by wrapping films and then shipped so that the cassette cases may be protected from being damaged when transported or displayed on the show window or that the cassette cases may be improved in appearance (design). In the prior art, a cassette case is wrapped by a wrapping film as follows. As shown in FIG. 1 of the accompanying drawings, a wrapping film 21 made of a polypropylene (PP) is provided in a roll form and cut to have a predetermined length a. Then, as shown in FIG. 2, a cassette case is wrapped by the wrapping film 21 and partly overlapping portions are bonded (i.e., heat-sealed) to hold the cassette case in a sealed condition. As illustrated, there are provided a center sealing surface 22 and a side sealing surface 23, respectively. End edge portions of the center sealing surface 22 and the side sealing surface 23 are served as sealing areas 22a, 23a, respectively. While it is customary that the wrapping film 21 is wholly printed in color, the sealing areas 22a, 23a are not applied with inks. Accordingly, when the sealing areas 22a, 23a are heated under the condition that the cassette case is wrapped by the wrapping film 21, the wrapping film 21 made of polypropylene is melt-bonded to heat-seal the wrapping film 21. The product in which the cassette case is wrapped by the polypropylene wrapping film 21 and tightly sealed by the heat-seal has a V-shaped notch 24 formed at one portion of the bonding portion on the center sealing surface 22 as shown in FIG. 2. The user can catch the notch 24 with a fingernail to tear the wrapping film 21 from the product. DE-U-8803229 is an exemple of such a prior art. FIGS. 3A and 3B show another example of the conventional wrapping film 21 having a so-called tearing strip 25 extended along the inner periphery of the wrapping film 21. The tearing strip 25 is interposed between the cassette case and the wrapping film 21 and wound around the outer periphery of the cassette case. One end of the tearing strip 25 is projected from the wrapping film winding end as a tab portion. The wrapping film 21 has slits formed at both sides of the tearing strip 25 so that the user can tear the wrapping film 1 along the tearing strip 25. Therefore, the user can hold the tab portion and tear the wrapping film 21 along the slits to open the wrapped film 21. In the former wrapping film 21 having the V-shaped notch 24 formed at the bonding portion on the center sealing surface 22, the bonding portion has a large bonding strength so that the user cannot tear the wrapping film 21 from the center sealing surface 22 with ease. Thus, it is cumbersome for the user to open the wrapping film 21. The latter wrapping film 21 having the tearing strip 25 also cannot avoid the following disadvantage. That is, if the user tears the wrapping film 21 along only the tearing strip 25 as shown in FIG. 3B, then the user cannot substantially tear the remaining wrapping film 21 even with a fingernail. Therefore, the wrapping film 21 is very difficult to be opened. The tearing strip 25 is made of a material whose tear propagation resistance is higher than that of the wrapping film 21. By way of example, the tearing strip 25 is formed by bonding two kinds of transparent plastic films. When the tearing strip 25 is formed as a color tearing strip, the surface of one film material is printed and then bonded to the other film material. The cassette case as a wrapped product is wrapped by the wrapping film made of the aforesaid material when the two films are melt-bonded to each other by the heat treatment of the wrapping film. However, since the surface of the cassette case is tightly wrapped by the wrapping film by heating the wrapping film at temperature higher than necessary in order to improve the appearance of the cassette case after the cassette case was packaged, the tab portion of the tearing strip also is bonded to the melt-bonded portion of the wrapping film. There are then the problems that the user cannot find the tab portion of the tearing strip without difficulty and that the user cannot tear the tab portion without difficulty. In particular, when the user wants to supplement tapes in order to record sound or picture in a hurry, the user cannot open the wrapping film readily. There is then the problem that the user misses the opportunity to effect such recording. OBJECTS AND SUMMARY OF THE INVENTION Therefore, it is a general object of the present invention to provide a case for accommodating therein a data storage or recording medium cartridge in which the aforesaid shortcomings and disadvantages encountered with the prior art can be eliminated. More specifically, it is an object of the present invention to provide an improved wrapping film for wrapping a case that accommodates therein a data storage or recording medium cartridge and in which the aforesaid shortcomings and disadvantages of the prior art can be eliminated. It is another object of the present invention to provide a wrapping film in which a wrapping film can be opened reliably and readily when the user tears the wrapping film. It is a further object of the present invention to provide a wrapping method in which a wrapping film can be torn from a bonding portion with ease and removed when the user opens the wrapping film. According to a first aspect of the present invention, there is provided a wrapped case for accommodating therein a data storage or recording medium cartridge, or cassette which comprises a wrapping film having a heat sealing area and a printing area, and said film wrapping the case, characterised in that said heat sealing area and said printing area are bonded together by heat and by a tearing strip wound around an outer periphery of the case for tearing the wrapping film, wherein one end of the tearing strip has a tab portion projected from the heat sealing area, and at least either the other side of the tab portion or the wrapping film portion opposed to the position of the other side of the tab portion is formed as a low adhesion portion which is bonded at a bonding strength smaller than that of the heat sealed portion. According to a second aspect of the present invention, there is provided a wrapping film for wrapping a case that accommodates therein a data storage or recording medium cartridge or cassette which comprises heat sealing areas put one on the other when the case is wrapped and bonded by heat, a printing area on which decorations are printed, and a device for tearing the wrapping film, characterised in that a bonding area is reduced substantially uniformly in the entirety of the heat sealing area. According to the wrapping film of the present invention, since the low adhesion portion is formed on at least either the other side of the tab portion of the tearing strip or on the wrapping film surface to which the other side of the tab portion is opposed, the tab portion can be prevented from being bonded to the wrapping film surface when the wrapping film is melt-bonded. As a consequence, the user can hold the tab portion with ease and therefore open the wrapping film reliably and readily. Furthermore, since the bonding strength of the heat sealing portion is decreased, the user can tear the wrapping film from the bonding portion with ease and open the wrapping film easily. The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof to be read in conjunction with the accompanying drawings, in which like reference numerals are used to identify the same or similar parts in the several views. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram used to explain a conventional wrapping film; FIG. 2 is a perspective view illustrative of an example of a conventional wrapping film having no tearing strip; FIGS. 3A and 3B are perspective views illustrative of an example of a conventional wrapping film having a tearing strip; FIG. 4 is a perspective view of a wrapping film according to a first embodiment of the present invention and illustrating the condition that the wrapping film is in the expanded state; FIG. 5 is a perspective view of the same wrapping film while a cassette case is being wrapped by the wrapping film; FIG. 6 is a perspective view of the same wrapping film and illustrating the condition that the cassette case is wrapped by the wrapping film; FIG. 7 is an enlarged cross-sectional view taken through the line VII - VII in FIG. 6; FIG. 8 is a perspective view of a wrapping film according to a second embodiment of the present invention and illustrating the condition that the wrapping film is in the expanded state; FIG. 9 is a perspective view of the same wrapping film while a cassette case is being wrapped by this wrapping film; FIG. 10 is a cross-sectional view illustrating the same wrapping film in an enlarged scale under the condition that the cassette case is wrapped by this wrapping film; FIG. 11 is a perspective view of a wrapping film according to a third embodiment of the present invention and illustrating the condition that the cassette case is being wrapped by the wrapping film; FIG. 12 is a perspective view of the same wrapping film and illustrating the condition that the cassette case is wrapped by the wrapping film; FIG.; 13 is a perspective view of the same wrapping film and illustrating the condition that the wrapping film is being opened; FIG. 14 is a front view illustrating an example of a low adhesion portion of the same wrapping film concretely in an enlarged scale; FIG. 15 is a cross-sectional view taken through the line XV - XV in FIG. 14; FIG. 16 is a perspective view of a wrapping film according to a fourth embodiment of the present invention; FIGS. 17A and 17B are side views of the same wrapping film, respectively; FIG. 18 is a perspective view of a wrapping film according to a fifth embodiment of the present invention; FIG. 19 is a side view of a wrapping film according to a sixth embodiment of the present invention; and FIG. 20 is a side view of a wrapping film according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the wrapping film according to the present invention will now be described with reference to the drawings. As shown in FIG. 4, a wrapping film according to a first embodiment of the present invention is composed of a thin film-shaped wrapping film 1 made of heat-shrinkable polypropylene and a film strip formed by bonding two kinds of plastic films which are colored and harder than the wrapping film 1 to be torn. This film strip is an adhesive tearing strip 2 having a non-ductile property. An outer peripheral edge of the wrapping film 1 is used as a melt-bonding portion 4 that is used to wrap a cassette case 3 in which there is accommodated a tape cassette which is a wrapped product. Most of the wrapping film 1 surface except the melt-bonding portion 4 is used as a printing surface 5 which is printed in a predetermined manner so as to show explanations on the accommodated tape cassette product. The tearing strip 2 is bonded to the wrapping film 1 by virtue of a melt-bonding property of the non-ductile film. When the cassette case 3 is wrapped by the wrapping film 1, the tearing strip 2 is interposed between the wrapping film 1 and the cassette case 3 and the cassette case 3 is wrapped at the portion near one end thereof. Therefore, the wrapping film 1 can be divided by the tearing strip 2 serving as a border line into a first wrapping film portion 1a that wraps one end of the cassette case 3 and a second wrapping film portion 1b that wraps most of the other end portion of the cassette case 3. One end portion of the tearing strip 2 forms a tab portion 6 that is projected from the end portion of the wrapping film 1 by a predetermined length to thereby enable the user to tear and open the wrapping film 1. The wrapping film 1 has at its respective portions of the tab portion 6 notches 7, 7 of predetermined lengths which serve as guide portions used when the user tears the wrapping film 1. The surface of the wrapping film 1 to which the other end portion of the tearing strip 2 is bonded is printed by some suitable surface printing process such as gravure printing or the like to form a low adhesion portion 8 in which the tab portion 6 can be prevented from being melt-bonded on the wrapping film 1 at this portion. That is, the cassette case 3 is wrapped by the wrapping film 1 as shown in FIG. 5 and the cassette case 3 is finally wrapped by the wrapping film 1. Then, as shown in FIG. 6, when the melt-bonding portion 4 is melt-bonded by the heat-seal treatment and the cassette case 3 is tightly wrapped by the wrapping film 1, the tab portion 6 of the tearing strip 2 and the nearby tearing strip portion are overlapped onto the surface of the low adhesion portion 8. Therefore, even if the overlapped wrapping end of the wrapping film 1 that wraps the cassette case 3 is melt-bonded at the melt-bonding portion 4 by the heat-seal process at excessively high temperature, the tab portion 6 of the tearing strip 2 can be prevented from being bonded in the melt-bonding portion 4 facing the tab portion 6 of the tearing strip 2 because the low adhesion portion 8 is formed, as shown in FIG. 7 in an enlarged scale. Thus, the user can hold the tab portion 6 with ease. A second embodiment of the present invention will be described below with reference to FIGS. 8 to 10. In a wrapping film of the second embodiment of the present invention, a low adhesion portion 9 is formed by printing on the surface of the tab portion 6 and the surface portion of the nearby tearing strip 2 according to some suitable surface printing process, such as a gravure printing or the like, as shown in FIGS. 8 and 9. Therefore, according to the thus arranged wrapping film, even if the overlapped winding end of the wrapping film 1 that wraps the cassette case 3 is melt-bonded at the melt-bonding portion 4 by the heat-seal process at temperature higher than necessary, as shown in FIG. 10, the tab portion 6 of the tearing strip 2 can be prevented from being bonded to the opposing melt-bonding portion 4. Thus, the user can hold the tab portion 6 with ease similarly to the aforesaid embodiments. A third embodiment of the present invention will be described below. In the wrapping film of this embodiment, as shown in FIGS. 11 and 12, the melt-bonding portion 4 is printed at the wrapping film 1 side opposite to that of the tab portion 6 of the tearing strip 2 and of the larger wrapping film adjacent to the tab portion 6 in a predetermined range (e.g., 20 to 30 mm) to thereby form a low adhesion portion 10 to which the wrapping film is difficult to be bonded. According to this wrapping film, even when the wrapping film 1 that wraps the cassette case 3 has its overlapped winding ends melt-bonded to the melt-bonding portion 4 by the heat-seal process at a temperature higher than necessary, the wrapping film portion of the low adhesion portion 10 is decreased in melt-bonding force. Since the low adhesion portion 10 is formed so that, when the user holds the tab portion 6 of the tearing strip 2 to open the wrapping film as shown in FIG. 13. the wrapping film 1 can be torn by the notch 7 and that the wrapping film portion opposing the low adhesion portion 10 can be torn with ease. Therefore, the user can readily and reliably open the wrapping film of larger film area which had imposed a cumbersome work on the user to open the wrapping film. The aforesaid low adhesion portion 10 might be a complete non-adhesive portion. In that case, under the product condition that the cassette case is wrapped by the wrapping film, it is frequently observed that the wrapping film of the low adhesion portion 10 is torn or the wrapping film is torn off from that portion unnecessarily, bringing about inferior products. A halftone printing portion 11 shown in FIGS. 14 and 15 is provided as a concrete example of the low adhesion portion 10. The halftone printing portion 11 is composed of halftone non-printing surfaces 11a in thin strips and printing surfaces 11b that occupy most of the remaining portion of the halftone printing portion 11. Under the condition that the cassette case 3 is sealed by the halftone printing portion 11, the overlapped surface of the wrapping film 1 is partly melt-bonded so that the wrapping film 1, provided as the wrapped product, can be prevented from being torn off unnecessarily. In addition, when the user holds the tab portion 6 of the tearing strip 2 to open the wrapping film 1, the melt-bonding portion 4 of the halftone printing portion 11 can be torn with ease. In this embodiment, since the other side of the tab portion 6 is not printed at all, the other side of the tab portion 6 is frequently bonded to the opposing surface of the wrapping film 1 by the heat-seal treatment. Therefore, the other side of the tab portion 6 must be prevented from being bonded to the surface of the wrapping film 1 by printing this other side of the tab portion 6. A fourth embodiment of the present invention will be described with reference to FIG. 16 and FIGS. 17A, 17B. As shown in FIG. 16 and FIGS. 17A, 17B, a so-called halftone printing portion 30 is printed on the entirety of the respective bonding portions (melt-bonding surfaces by heat, i.e., sealing areas 22a, 23a shown in FIG. 1) of the center sealing surface 22 and the side sealing surface 23 of the wrapping film 1. A portion 31 other than the above halftone printing portion 30 is printed wholly in an ordinary printing manner. The halftone is printed on the melt-bonding portion of the wrapping film 21 so that, when the wrapping film 21 is melt-bonded by heat, the printing portion is not melt-bonded and the portion that is not printed is melt-bonded in a dot pattern. As a result, the whole bonding area is decreased substantially uniformly, decreasing a bonding strength more as compared with the prior art. Thus, the wrapping film 21 can be torn from the notch 24 of the center sealing surface 23 with ease. A fifth embodiment of the present invention will be described below with reference to FIG. 18. FIG. 18 shows a modified example of the fourth embodiment shown in FIG. 16 and FIGS. 17A, 17B. In this embodiment, the bonding portion is printed only at its one portion near the notch 24 in a whole printing fashion unlike the halftone printing portion 30, i.e., such portion is formed as the portion that cannot be melt-bonded even when heated, Therefore, when the user opens the wrapping film, the user can hold the notch 24 with the fingernail with ease. FIG. 19 shows a wrapping film having the tearing strip 25 according to a sixth embodiment of the present invention. Even when the tearing strip 25 is torn as shown in FIG. 3B, the user can tear the wrapping film 21 from the bonding portion one more time because the bonding strength of the bonding portion is decreased by the halftone printing. A seventh embodiment of the present invention will be described with reference to FIG. 20. In the wrapping film 21 having the tearing strip 25, if the bonding portion is changed at its one portion near the tearing strip 25 from the halftone printing portion 30 to the whole printed portion, then the user can open the wrapping film more easily. The low adhesion portions 8, 9 in the wrapping films of the first and second embodiments are not limited to the whole surface printing such as a gravure printing or the like and may be formed by the halftone printing as in the third embodiment. Further, other methods may be employed so long as similar action, achieved by the halftone printing, can be achieved. While the tearing strip 2 is bonded to the wrapping film 1 by means of adhesion of non-ductile polypropylene as described above, the present invention is not limited thereto and the tearing strip 2 may be melt-bonded to the wrapping film 1 by other methods such as hot-melt or the like. While the wrapping film of the present invention is used to tightly wrap the cassette case in which the tape cassette is accommodated or the like as described above, the present invention is not limited thereto and the wrapping film of the present invention may be applied to a wide variety of wrapping films for the wrapped products. According to the present invention, a bonding strength can be arbitrarily set by changing a size of halftone printing. Further, while the bonding area of the bonding portion is uniformly reduced by the halftone printing as described above, the present invention is not limited to such halftone printing and other printing patterns (e.g., a stripe pattern) may be used. As set out above, according to the present invention, there is provided the wrapping film that tightly wraps the wrapped product and in which the user can open the wrapping film by holding the tearing strip having the tab portion. In this wrapping film, the low adhesion portion is formed on either the other side of the tab portion of the tearing strip or on the wrapping film surface to which the other side of the tab portion is opposed so that, when the wrapped product is wrapped and then sealed by the wrapping film, the tab portion of the tearing strip can be prevented from being melt-bonded to the wrapping film surface. Therefore, the user can hold the tab portion with ease to open the wrapping film reliably and readily. Furthermore, there is provided a wrapping method in which a wrapped product is wrapped by a wrapping film and the overlapping portions of the wrapping film are sealed by heat seal treatment. In this wrapping method, the heat seal portion is printed by some suitable printing method such as halftone printing or the like that can uniformly reduce the bonding area of the whole bonding portion and the bonding strength can be decreased. Therefore, when the user opens the wrapping film, the wrapping film can be peeled from the bonding portion with ease and removed. Particularly, a wrapping film on which a picture is wholly printed can be provided as the wrapping film of the present invention inexpensively by forming one portion thereof as a halftone printing. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various changes and modifications could be effected therein by one skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims: A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette comprising: (a) a wrapping film (1) having a heat sealing area and a printing area, said film wrapping said case (3), characterised in that said heat sealing area and said printing area are bonded together by heat and in that there is provided: (b) a tearing strip (2) wound around an outer periphery of said case (3) for tearing said wrapping film (1), wherein one end of said tearing strip (2) has a tab portion (6) whereby the end projects from said heat sealing area, and at least either the inner face of said tab portion or the wrapping film portion facing said inner face of said tab portion (6) if formed as a low adhesion portion (8; 9; 10) which is bonded at a bonding strength smaller than that of said heat sealed portion. A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette according to claim 1, wherein said low adhesion portion (8) is formed on said wrapping film portion corresponding to a position opposite to the inner face of said tab portion (6) of said tearing strip (2) in a predetermined range of a direction perpendicular to said tearing strip (2). A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette according to claim 1 or 2, wherein said tearing strip (2) is wound around said case (3) at its outer periphery at a portion near an end of the case so that said strip divides the wrapping film into a small portion (8a) and a large portion (8b), wherein said low adhesion portion is formed on the large wrapping film portion. A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette according to claim 1, wherein said low adhesion portion (9) is formed on the inner face of said tab portion (6) of said tearing strip (2). A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette according to any one of claims 1 to 4, wherein said low adhesion portion (10) is printed partly or wholly. A wrapped case for accommodating therein a data storage or recording medium cartridge or cassette according to any one of claims 1 to 5, wherein said low adhesion portion (11; 30) is printed in a halftone fashion. A wrapping film for wrapping a case that accommodates therein a data storage or recording medium cartridge or cassette, comprising: (1) heat sealing areas (22a, 23a) to be put one on the other when said case (3) is wrapped and melt-bonded by heat; (2) a printing area (30, 31) on which decorations are printed; and (3) means (24; 25) for tearing said wrapping film (1), characterised in that a bonding area is reduced substantially uniformly in the entirety of said heat sealing areas (22a, 23a). A wrapping film according to claim 7, wherein the entirety of said heat sealing areas (22a, 23a) is halftone printed. A wrapping film according to claim 8, wherein said wrapping film tearing means is a V-shaped notch (24). A wrapping film according to claim 8, wherein said wrapping film tearing means is a tearing strip (25) that is wound around said case at its outer periphery near one end. A case for accommodating therein a data storage medium cassette said case being wrapped by the wrapping film of any one of claims 7 to 10.

Inventors: OZAKI HIROSHI, SEKI SEIZO, OZAKI, HIROSHI, SEKI, SEIZO, OZAKI, HIROSHI, C/O SONY CORPORATION, Seki, Seizo, c/o Sony Corporation
Applicants: SONY CORP, SONY CORPORATION
Application year: 1993
Main classification: B65D75
IPC codes: B65D75