Rice ball packaging sheet and packaged rice ball

Abstract

The present invention provides a rice ball packaging sheet that allows easy unpacking. A rice ball food packaging sheet 1 according to the present invention: includes an outer film 2, an inner film 3 which is disposed in a layered manner on the outer film and which is separable into right and left portions, and a sheet-like food 4 which is sandwiched between the outer film and the inner film; and is obtained by heat-sealing the outer film and the inner film together along the outer periphery of the sheet-like food. The outer film has an outer groove 21 which is recessed relative to the surface of the outer film and which is formed by laser processing. Outer bank sections 22 which are raised relative to the surface of the outer film are formed on both sides of the outer groove.

Description

Rice ball packaging sheet and packaged rice ball

[0001] The present invention relates to a rice ball packaging sheet configured by sandwiching a sheet-shaped food between an inner film and an outer film and capable of packaging rice balls and the like, and a packaged rice ball obtained by packaging a rice ball with the rice ball packaging sheet.

[0002] As a rice ball packaging sheet for packaging rice balls sold at convenience stores and the like, a triple-structured packaging sheet formed by sandwiching sheet-shaped nori between an outer film and an inner film is widely known.

[0003] In the conventional outer film, a cut tape for dividing the outer film is attached at the center in the width direction, and the inner film is composed of two inner film pieces. Sheet-shaped nori is sandwiched between the outer film and the inner film pieces, and the inner ends of the two inner film pieces are heat-sealed to the outer film so as to overlap on the cut tape of the outer film to produce a packaging sheet (see, for example, Patent Document 1).

[0004] For the packaged rice ball obtained by packaging a rice ball with the above packaging sheet, after pulling the start end of the cut of the cut tape to divide the outer film into two, by pulling one of the outer films outward, the inner film pieces are pulled out together with the outer film (see, for example, Patent Document 2).

[0005] Subsequently, by pulling the other outer film outward and pulling it out together with the remaining inner film piece, a nori-wrapped rice ball in which sheet-shaped nori is directly wound around the rice ball can be obtained and eaten.

[0006] Further, Patent Document 3 discloses a rice ball packaging sheet in which groove-shaped half-cuts are respectively formed at the centers in the width direction of the outer film and the inner film. For the packaged rice ball obtained by packaging a rice ball with this rice ball packaging sheet, by pulling the outer film and the inner film in a direction perpendicular to the half-cut, the half-cut is divided and the packaging can be opened.

[0007] JP-A-2002-101832, Utility Model Publication No. 6-8284, JP-A-2008-100741

[0008] In the rice ball packaging sheets using cut tape as shown in Patent Documents 1 and 2, the position of the starting end of the cut tape is not clear during the procedure for unpacking the rice ball, and even if the starting end is clear, it may be difficult to grasp the starting end properly, making it impossible to unpack. This is especially difficult for people eating packaged rice balls for the first time or for the elderly. If the packaging of the rice ball is unpacked using an incorrect method, the sheet-like food may tear, and it may also be difficult to properly wrap the sheet-like food around the rice ball.

[0009] Furthermore, conventional inner films simply overlap the inner edges of two inner film pieces. Consequently, during the manufacturing and distribution process, or after the rice balls are packaged, moisture can penetrate through the overlapping sections of the inner film pieces, causing the sheet of nori to become damp. Additionally, while the outer film and inner film pieces are heat-sealed around the periphery of the sheet of nori, there are unsealed sections within the periphery that allow for separation with cutting tape. As a result, moisture can penetrate through these unsealed sections, causing the sheet of nori to become damp. When the sheet of nori becomes damp, it can become sticky, wrinkled, and wavy, resulting in an inferior appearance and taste, and there is a risk of it tearing when the rice ball packaging is opened.

[0010] In the rice ball packaging sheet described in Patent Document 3, when the outer film and inner film are pulled, the tear line of the film may deviate from the half-cut. As a result, the separation points of the outer film and inner film may not align, or the outer film and inner film may not be completely separated, with parts remaining connected, making it difficult to unpack the packaging properly.

[0011] The object of the present invention is to provide a rice ball packaging sheet and a packaged rice ball that can be easily unpacked and, in a more preferred embodiment, prevents the sheet-like food from becoming damp.

[0012] The rice ball packaging sheet of the present invention comprises an outer film, an inner film placed on top of the outer film, and a sheet-like food sandwiched between the outer film and the inner film, wherein the outer film and the inner film are heat-sealed together at the outer circumference of the sheet-like food, and the outer film has an outer groove formed by laser processing that is recessed from the surface of the outer film, and outer edges that are raised from the surface of the outer film are formed on both sides of the outer groove.

[0013] The inner film can consist of two inner film pieces, with the inner ends of the inner film pieces overlapping at a position facing the outer groove.

[0014] The inner film consists of a single film, and the inner film has an inner groove formed by laser processing that is recessed from the surface of the inner film, and on both sides of the inner groove, there are inner embankments that are raised from the surface of the inner film.

[0015] The groove film thickness I1 of the outer film in the portion where the outer groove is formed is preferably 1 / 4 to 3 / 4 of the outer film thickness H1.

[0016] Preferably, the thickness H1 of the outer film is 10 μm to 40 μm, the groove film thickness I1 of the outer film in the portion where the outer groove is formed is 5 μm to 30 μm, and the height L1 of the outer embankment portion from the surface of the outer film is 3 μm to 30 μm.

[0017] Preferably, the groove film thickness I2 of the inner film in the portion where the inner groove is formed is 1 / 4 to 3 / 4 of the inner film thickness H2, the inner film thickness H2 is 10 μm to 40 μm, the groove film thickness I2 of the inner film in the portion where the inner groove is formed is 5 μm to 30 μm, and the height L2 of the inner bank portion from the surface of the inner film is 3 μm to 30 μm.

[0018] Preferably, the outer film has the outer groove and outer edge formed on the inner surface of the sheet-like food side.

[0019] Preferably, the inner film has the inner groove and the inner bank formed on the inner surface opposite to the sheet-like food.

[0020] Preferably, the outer film and the inner film are heat-sealed together so as to completely surround the outer periphery of the sheet-like food product.

[0021] Furthermore, the packaged rice ball of the present invention is made by packaging the rice ball with the rice ball packaging sheet described above.

[0022] The rice ball packaging sheet according to the present invention has an outer film with an outer groove and outer edge formed by laser processing. When the outer film is pulled outward in a direction approximately perpendicular to the outer groove, the outer film is separated starting from the thin outer groove. In this invention, both sides of the outer groove are reinforced by the outer edge, so the tear line of the outer film is guided by the outer groove and proceeds along the outer groove without deviating. As a result, the packaging of the rice ball can be easily removed by simply pulling the outer film and inner film outward.

[0023] Furthermore, in the embodiment (Embodiment 1) in which the inner film is made from a single film and is provided with an inner groove and an inner bank, since the inner film is not made from two inner film pieces as in the conventional method, moisture does not penetrate from the overlapping parts of the inner film pieces. Therefore, moisture can be prevented from becoming damp in the sheet-shaped food. Moreover, in this embodiment, since no cut tape is used, the outer film and inner film can be heat-sealed together on their entire outer perimeter. As a result, there are no unsealed areas on the outer perimeter of the packaging sheet from which moisture can penetrate, thus preventing moisture from becoming damp in the sheet-shaped food. Consequently, the sheet-shaped food can be kept dry, reducing stickiness, wrinkles, warping, deterioration of appearance and taste, and also reducing the likelihood of the sheet-shaped food tearing when unwrapping packaged rice balls.

[0024] Furthermore, in the case of rice ball packaging sheets that use cut tape, there are three pieces of waste: the outer film and inner film that are separated into left and right halves, and the outer film to which the cut tape is attached. However, with the rice ball packaging sheet of the present invention, there are only two film blocks: the outer film and inner film that are separated into left and right halves, thus reducing the number of waste pieces.

[0025] Figure 1 is an exploded perspective view of an onigiri packaging sheet according to Embodiment 1 of the present invention. Figure 2 is a plan view of an onigiri packaging sheet according to Embodiment 1 of the present invention. Figure 3 is a cross-sectional view along line A-A in Figure 2. Figure 4 is (a) a cross-sectional view in a direction perpendicular to the outer groove of the outer film of Embodiment 1, and (b) a cross-sectional view in a direction perpendicular to the inner groove of the inner film. Figure 5 is an enlarged view of the circled area B in Figure 3. Figure 6 is a perspective view of a packaged onigiri made by packaging an onigiri with the packaging sheet of Embodiment 1. Figure 7 is a perspective view of the packaged onigiri of Embodiment 1 viewed from the back. Figure 8 is a schematic diagram of the main parts of the packaging sheet manufacturing apparatus of Embodiment 1. Figure 9 is an exploded perspective view of another pattern (wavy groove) of the packaging sheet according to Embodiment 1 of the present invention. Figure 10 is a diagram showing the shape measurement results of the film of the inventive example using a digital microscope. Figure 11 is a diagram showing the shape measurement results of the film of the comparative example using a digital microscope. Figure 12 is a photograph of the outer film of the inventive example with linear grooves after it has been cut. Figure 13 is a photograph of the inner film of the inventive example with linear grooves after it has been cut apart. Figure 14 is a photograph of the outer film of the inventive example with wavy grooves after it has been cut apart. Figure 15 is a photograph of the inner film of the inventive example with wavy grooves after it has been cut apart. Figure 16 is a photograph of the outer film of the comparative example with linear grooves after it has been cut apart. Figure 17 is a photograph of the inner film of the comparative example with linear grooves after it has been cut apart. Figure 18 is a photograph of the outer film of the comparative example with wavy grooves after it has been cut apart. Figure 19 is a photograph of the inner film of the comparative example with wavy grooves after it has been cut apart. Figure 20 is an exploded perspective view of the rice ball packaging sheet according to Embodiment 2 of the present invention. Figure 21 is a plan view of the rice ball packaging sheet according to Embodiment 2 of the present invention. Figure 22 is a cross-sectional view along the line A-A in Figure 21. Figure 23 is a cross-sectional view in a direction perpendicular to the outer groove of the outer film used in Embodiment 2. Figure 24 is an enlarged view of the circled area B in Figure 22. Figure 25 is a schematic diagram of the main parts of the packaging sheet manufacturing apparatus used in Embodiment 2. Figure 26 is an exploded perspective view of another pattern (wavy groove) of the packaging sheet according to Embodiment 2 of the present invention.

[0026] The rice ball packaging sheet 1 of the present invention will be described below with reference to the drawings.

[0027] <Embodiment 1> As shown in Figure 1, the packaging sheet 1 for the rice ball 5 of the present invention is composed of an outer film 2, a sheet-like food 4, and an inner film 3. The outer film 2 and the inner film 3 are overlapped so as to sandwich the sheet-like food 4. As shown in Figures 2 and 3, the outer film 2 and the inner film 3 are heat-sealed 11 so as to completely surround the outer periphery of the sheet-like food 4, and are integrated to form the packaging sheet 1. In this embodiment, the outer film 2 and the inner film 3 are each composed of one film.

[0028] <Outer film 2, inner film 3> The outer film 2 and inner film 3 can be rectangular. In the illustrated embodiment, films 2 and 3 are rectangles with a length of approximately 23 cm and a width of approximately 16 cm.

[0029] The outer film 2 and inner film 3 can be made from common materials used for rice ball packaging sheets, such as polypropylene film (PP film) like CPP film or OPP film, or polyethylene film (PE film). The outer film 2 can be, for example, a transparent film, and the product name and ingredients can be printed on it as appropriate. The inner film 3 can be a transparent or opaque film.

[0030] The thicknesses H1 and H2 (see Figure 4) of the outer film 2 and inner film 3 are preferably 10 to 40 μm, and more preferably 20 to 30 μm. If the film thicknesses H1 and H2 are thinner than this, sufficient strength cannot be achieved, and if the film thicknesses H1 and H2 are thicker than this, it may become difficult to wrap the rice ball 5, and costs will increase.

[0031] The packaging sheet 1 of this embodiment has grooves 21 and 31 that allow the outer film 2 and inner film 3 to be easily torn apart by pulling them to the left and right when unpacking, as shown in Figure 4. The groove formed in the outer film 2 is called the outer groove 21, and the groove formed in the inner film 3 is called the inner groove 31. On both sides of the outer groove 21, there are outer embankments 22 that are raised higher than the surface of the outer film 2, and on both sides of the inner groove 31, there are inner embankments 32 that are raised higher than the surface of the inner film 3.

[0032] The outer groove 21, with outer embankment portions 22 formed on both sides, and the inner groove 31, with inner embankment portions 32 formed on both sides, can be formed by, for example, irradiating films 2 and 3 with a laser beam, although the manufacturing method is not limited. Figure 4(a) is an enlarged view of the outer groove 21 formed on the outer film 2 by laser processing, and Figure 4(b) is an enlarged view of the inner groove 31 formed on the inner film 3 by laser processing. As shown in the figures, it can be seen that a part of the surface of the outer film 2 and inner film 3 melts and becomes thinner when irradiated with a laser. On both sides of the outer groove 21 and inner groove 31, a part of the melted resin flows to the left and right, forming raised embankment portions 22 and 32.

[0033] As shown in Figures 6 and 7, the outer groove 21 and inner groove 31 can be formed along the entire length of the outer film 2 and inner film 3, following a line connecting one vertex of the rice ball 5 to the center of the opposite side when the rice ball 5 is wrapped. In the unfolded state, as shown in Figures 1 and 2, this corresponds to approximately the center in the short direction of the outer film 2 and inner film 3.

[0034] The outer groove 21 and inner groove 31 are preferably formed such that the thickness of the film 2 and 3 in the portion where the outer groove 21 and inner groove 31 are formed (groove film thickness) I1 and I2 are approximately 1 / 4 to 3 / 4 of the film thickness H1 and H2, respectively, as shown in Figure 4, and more preferably 1 / 3 to 1 / 2. Specifically, the groove film thickness I1 and I2 are 5 μm to 30 μm, preferably 10 μm to 25 μm.

[0035] In the case of the groove film thicknesses I1 and I2 described above, as shown in Figure 4, the depths J1 and J2 of the outer groove 21 and inner groove 31, including the bank portions 22 and 32, are 10 μm to 25 μm, preferably 15 to 20 μm. At this time, the groove depths K1 and K2 from the film surface to the bottom of the outer groove 21 and inner groove 31 are 5 μm to 20 μm.

[0036] Furthermore, the heights L1 and L2 of the embankment sections 22 and 32 (embankment heights) are preferably about 3 μm to 30 μm, more preferably 3 μm to 20 μm, and most preferably 5 μm to 15 μm. The embankment sections 22 and 32 are necessary to have a predetermined height in order to serve as reinforcement to prevent the break from diverting towards the film side when the outer groove 21 and inner groove 31 are separated. When the embankment heights L1 and L2 are as described above, the embankment film thicknesses M1 and M2 in the parts where the embankment sections 22 and 32 are formed will be H1 + L1 for M1 and H2 + M2 for M2, respectively. Therefore, in the case of the above film thickness, the embankment film thicknesses M1 and M2 will be 13 μm to 70 μm, respectively.

[0037] The outer groove 21 and inner groove 31 may be formed on either the outer film 2 or the inner film 3, respectively. Specifically, the outer groove 21 can be formed on the outer surface of the outer film 2 that faces outward during packaging, or on the inner surface that faces the sheet-like food 4.

[0038] On the other hand, as shown in Figure 5, which is an enlarged view of the circled area B in Figure 3, it is desirable that the outer groove 21 formed on the outer film 2 be formed on the middle surface 24 facing the sheet-like food 4, and the inner groove 31 formed on the inner film 3 be formed on the inner surface 34 facing the rice ball 5. This is because if there is a raised outer edge 22 on the outer surface 23 of the outer film 2, it may feel uncomfortable when the purchaser touches it. Also, if the sheet-like food 4 is sheet-like seaweed, the back surface 42 is rough, and if the inner groove 31 of the inner film 3 is on the rough side of the sheet-like food 4, the inner edge 32 may catch on the rough sheet-like food 4 when unpacking, making it difficult to unpack.

[0039] <Sheet-shaped food 4> The sheet-shaped food 4 sandwiched between the outer film 2 and the inner film 3 can be exemplified by sheet-shaped seaweed. The sheet-shaped food 4 can be roughly rectangular in shape. The sheet-shaped food 4 may also be rectangular with chamfered corners or with rounded chamfered corners. In the illustrated embodiment, the sheet-shaped food 4 has a length of approximately 19 cm in the longitudinal direction and a length of approximately 10 cm in the transverse direction.

[0040] The sheet-shaped food 4 is not limited to sheet-shaped nori seaweed, and as long as it is a thin food, it is possible to adopt a thinly stretched surume or a sheet-shaped oboro kelp formed from oboro kelp.

[0041] <Packaging sheet 1> As shown in FIG. 1, the outer film 2, the sheet-shaped food 4, and the inner film 3 are stacked, and as shown in FIGS. 2 and 3, the outer film 2 and the inner film 3 are heat-sealed 11 so as to entirely surround the outer periphery of the sheet-shaped food 4, thereby producing the packaging sheet 1.

[0042] In the present embodiment, the packaging sheet 1 is composed of a single film for both the outer film 2 and the inner film 3. By providing the outer groove 21 in the outer film 2, a cut tape is unnecessary. Further, since the inner film 3 is not in a form where two inner film pieces are stacked, moisture intrusion can be prevented. Furthermore, since a cut tape is unnecessary, the outer film 2 and the inner film 3 can be heat-sealed along the entire outer periphery. Therefore, moisture intrusion into the packaging sheet 1 can be prevented, and the sheet-shaped food 4 getting wet can also be reduced.

[0043] <Rice ball 5> The rice ball 5 packaged by the above packaging sheet 1 can be a lump of rice formed by compacting white rice or cooked rice into a flat shape or a spherical shape, or a rod-shaped rice in a circular shape or a prismatic shape. For the rice ball 5, a sprinkled food such as sesame can be sprinkled partially or entirely, ingredients can be placed on it, or ingredients can be sandwiched inside. In the present embodiment, as shown in FIGS. 6 and 7, the rice ball 5 is in a triangular flat shape, but it can also be a round rice ball or a square rice ball.

[0044] <Packaged rice ball 6> The rice ball 5 is packaged by the packaging sheet 1 having the above configuration, resulting in the packaged rice ball 6. The packaging of the rice ball 5 can be performed by placing the packaging sheet 1 with the inner film 3 side facing upward on the rice ball 5 and covering the rice ball 5 with the packaging sheet 1 so as to wrap it as shown in FIGS. 6 and 7. Then, the packaged rice ball 6 can be obtained by fixing the overlapping portion of the packaging sheet 1 with a fixing means (not shown) such as a tape or heat-sealing.

[0045] <How to Open the Package of the Packaged Rice Ball 6> To open the package of the packaged rice ball 6, pinch the outer film 2 and pull it outward with both hands as indicated by arrow C in Fig. 6, substantially perpendicular to the outer groove 21 and the inner groove 31. As a result, the outer film 2 is pulled, and at the same time as pulling the outer film 2, the inner film 3 inside is also pulled. Thereby, the outer groove 21 and the inner groove 31 have groove portion film thicknesses I1 and I2 that are thinner than the film thicknesses H1 and H2 of the outer film 2 and the inner film 3. Therefore, when the outer film 2 and the inner film 3 are pulled, they break starting from the outer groove 21 and the inner groove 31 with a thin film thickness. The starting points of the breakage are the outer groove 21 and the inner groove 31 located on the bottom surface of the packaged rice ball 6.

[0046] From this state, when the outer film 2 and the inner film 3 are further pulled left and right, the breakage of the outer film 2 and the inner film 3 progresses. In the present invention, on both sides of the outer groove 21 and the inner groove 31, outer soil portions 22 and inner soil portions 32 are respectively formed. The soil portion film thicknesses M1 and M2 of the portions where these soil portions 22 and 32 are formed are reinforced to be thicker than the groove portion film thicknesses I1 and I2 of the portions where the grooves 21 and 31 are formed, as shown in Fig. 4. Therefore, the breakage of the film progresses along the outer groove 21 and the inner groove 31 without deviating from the grooves, and the outer film 2 and the inner film 3 are completely broken and separated. Then, the sheet-like food 4 is pulled out from between the separated outer film 2 and the inner film 3, and a seaweed-wrapped rice ball can be obtained in which the rice ball 5 is wrapped in the sheet-like food 4.

[0047] In the present invention, as described above, since the breakage of the films 2 and 3 progresses along the outer groove 21 and the inner groove 31, it is possible to prevent the breakage from deviating from the grooves and the separation points of the outer film 2 and the inner film 3 not matching, or the outer film 2 and the inner film 3 not being completely separated and remaining partially connected, thereby reducing the problem of not being able to properly open the package.

[0048] Furthermore, in the packaging sheet 1 of the present invention, both the outer film 2 and the inner film 3 are single films, and the outer film 2 and the inner film 3 can be heat-sealed around their entire outer circumference. Therefore, moisture penetration into the packaging sheet 1 can be prevented, and thus the moisture in the sheet-like food 4 can be reduced not only during the manufacturing and distribution process of the packaging sheet 1, but also in the state of the packaged rice ball 6 in which the rice ball 5 is wrapped.

[0049] According to the present invention, to unpack the packaged rice ball 6, one only needs to pinch the outer film 2 and pull it outwards. In other words, since a cut tape is not required, there is no need to pinch the starting end of the cut tape or to pinch and pull the cut tape in order to unpack the packaged rice ball 6. Furthermore, after unpacking, the outer film 2 and inner film 3 are separated into two film pieces, which become waste fragments, and the number of fragments can be reduced compared to the three fragments that are produced when a cut tape is used.

[0050] <Laser Processing and Method for Manufacturing Packaging Sheet 1> For manufacturing the packaging sheet 1 of this embodiment, the packaging sheet manufacturing apparatus 7 shown in Figure 8 can be used. The packaging sheet manufacturing apparatus 7 includes laser irradiation units 28 and 38.

[0051] The packaging sheet manufacturing apparatus 7 is a device that manufactures a packaging sheet 1 by sandwiching a sheet of food 4 between a long outer film strip 20 and a long inner film strip 30, applying heat sealing 11 to the outer film strip 20 and the inner film strip 30, and cutting it to a predetermined length.

[0052] The packaging sheet manufacturing apparatus 7 has a sheet food stocker 43 on the upstream side where sheet food 4 (sheet-shaped seaweed) is stacked. The sheet food 4 is pulled out one sheet at a time from the sheet food stocker 43 and transported downstream by a sheet food transport means 44 such as a conveyor.

[0053] The inner film strip 30 is wound around the inner film roll 35 and appears downstream of the sheet-like food conveying means 44 while changing direction via rollers 36, 37, etc. Then, the sheet-like food 4 is placed at predetermined intervals on the inner surface 34 side (see Figure 5) of the inner film strip 30 and moves downstream together with the inner film strip 30.

[0054] The inner groove 31 formed in the inner film 3 can be formed in the inner film strip 30 by, for example, arranging a laser irradiation unit 38 between rollers 36 and 37. The laser irradiation unit 38 has a head portion 38a that emits a laser beam 38b and irradiates the inner film strip 30 with the laser beam 38b. In the illustrated embodiment, the laser irradiation unit 38 is positioned so that the inner groove 31 is formed on the inner surface 34 side of the inner film strip 30 (see Figure 5), that is, on the side opposite to the sheet-like food 4.

[0055] The laser irradiation unit 38 is CO ２ A unit that irradiates with a laser as a laser beam 38b can be illustrated, but the laser beam 38b is CO ２ This is not limited to lasers. Furthermore, the output of the laser irradiation unit 38 is, for example, 10W to 30W, preferably 15W to 25W, on the inner film band 30 surface, and the width of the laser beam 38b is, for example, 50μm to 300μm, preferably 100μm to 250μm.

[0056] Furthermore, in order to stabilize the irradiation distance of the laser beam 38b to the moving inner film strip 30, it is preferable to provide a guide base 39 on the opposite side of the head portion 38a at the irradiation position of the laser beam 38b, while the inner film strip 30 is in contact with it as it travels. This allows the inner film strip 30 to travel stably without swaying, and the irradiation distance of the laser beam 38b can be kept constant.

[0057] The wavelength of the laser beam 38b is such that, depending on the material, thickness, and travel speed of the inner film strip 30, an inner groove 31 is formed with a predetermined groove depth K2, leaving a groove film thickness I2 (see Figure 4). Additionally, an inner embankment 32 with an embankment height L2 is formed on both sides of the inner groove 31. For example, if the travel speed of the inner film strip 30 made of PP film is 15 to 25 m / min, then with the output and width of the laser beam 38b described above, an inner groove 31 of the above dimensions can be formed in the inner film strip 30 by setting the wavelength to 5 μm to 15 μm.

[0058] As shown in Figure 8, the inner film strip 30, which has an inner groove 31 formed on it, travels with its direction of travel changed horizontally by the roller 37. Sheet-shaped food 4 is placed at predetermined intervals on the inner surface 33 (see Figure 5) of the horizontally traveling inner film strip 30 with its surface 41 (see Figure 5) facing upward, from the sheet-shaped food conveying means 44, and further downstream it overlaps with the outer film strip 20.

[0059] The outer film strip 20 is wound around the outer film roll 25 and, via rollers 26, 27, etc., emerges from above onto the inner film strip 30 on which the sheet-like food 4 is placed.

[0060] The outer groove 21 formed in the outer film 2 can be formed in the outer film strip 20, for example, by arranging a laser irradiation unit 28 between rollers 26 and 27. The laser irradiation unit 28 has a head portion 28a that emits a laser beam 28b and irradiates the laser beam 28b toward the outer film strip 20. In the illustrated embodiment, the laser irradiation unit 28 is positioned so that the outer groove 21 is formed on the inner surface 24 side (see Figure 5) of the outer film strip 20, that is, on the side facing the sheet-like food 4.

[0061] The laser irradiation unit 28 is CO ２ A unit that irradiates with a laser as a laser beam 28b can be illustrated, but the laser beam 28b is CO ２ This is not limited to lasers. Furthermore, the output of the laser irradiation unit 28 is, for example, 10W to 30W, preferably 15W to 25W, on the outer film band 20 surfaces, and the width of the laser beam 28b is, for example, 50μm to 300μm, preferably 100μm to 250μm.

[0062] Furthermore, in order to stabilize the irradiation distance of the laser beam 28b to the moving outer film strip 20, it is preferable to provide a guide base 29 on the opposite side of the head unit 28a at the irradiation position of the laser beam 28b, while the outer film strip 20 is in contact with it as it travels. This allows the outer film strip 20 to travel stably without swaying, and the irradiation distance of the laser beam 28b can be kept constant.

[0063] The wavelength of the laser beam 28b is determined according to the material, thickness, and travel speed of the outer film strip 20. An outer groove 21 is formed with a predetermined groove depth K1, leaving a groove film thickness I1 (see Figure 4) intact. Additionally, an outer embankment 22 with an embankment height L1 is formed on both sides of the outer groove 21. For example, if the travel speed of the PP film outer film strip 20 is 15 to 25 m / min, then with the above-described output and width of the laser beam 28b, an outer groove 21 of the above dimensions can be formed on the outer film strip 20 by setting the wavelength to 5 μm to 15 μm.

[0064] The outer film strip 20, on which the outer groove 21 is formed, travels with its direction of travel changed horizontally by the roller 27. Then, as it travels horizontally, it covers the inner film strip 30 on which the sheet-like food 4 is placed, and travels downstream with the sheet-like food 4 sandwiched between the outer film strip 20 and the inner film strip 30.

[0065] Next, the outer film strip 20 and inner film strip 30, which sandwich the sheet-like food 4, enter a sealing device 71 located downstream. The sealing device 71 is a device that heat-seals 11 the outer film strip 20 and the inner film strip 30. The sealing device 71 can be composed of, for example, rotating heat-sealing rollers 72 and 73, and heat-seals 11 is applied to both the left and right ends in the width direction of the outer film strip 20 and the inner film strip 30, and to the front and back of the sheet-like food 4, respectively (see Figures 2 and 3).

[0066] The heat-sealed outer film strip 20 and inner film strip 30 are then transported to a cutting device 74. The cutting device 74 can consist of a movable blade 75 and a fixed blade 76, and cuts the outer film strip 20 and inner film strip 30 at approximately the midpoint of the heat-sealed area 11 between the sheet-like food products 4, 4. This allows for the production of the packaging sheet 1 shown in Figure 2, etc.

[0067] The manufactured packaging sheets 1 are transported by a packaging sheet transport means 77, such as a conveyor, located downstream of the cutting device 74, stacked in a stocker (not shown), and shipped out.

[0068] <Different Embodiments of Outer Grooves 21 and Inner Grooves 31> In Figure 2, etc., the outer grooves 21 and inner grooves 31 are formed in a straight line, but they may also be wavy as shown in Figure 9, or jagged, although not shown. Wavy or jagged outer grooves 21 and inner grooves 31 can be formed by moving the heads 28a and 38a that irradiate the laser beams 28b and 38b from side to side with respect to the running direction of the outer film strip 20 and inner film strip 30. Even in this case, outer embankments 22 and inner embankments 32 are formed on both sides of the outer grooves 21 and inner grooves 31 along the shape of the wavy or jagged grooves 21 and 31. By forming the outer grooves 21 and outer embankments 22, and the inner grooves 31 and inner embankments 32 in a wavy or jagged shape, the outer film 2 and inner film 3 can be torn more easily compared to a straight line, making it easier to unpack the packaged rice ball 6. This is thought to be because, compared to straight outer grooves 21 and inner grooves 31, stress tends to concentrate at the peaks of the wavy or jagged outer grooves 21 during tearing, allowing the starting point of the fracture to be formed with less force. In addition, the resistance is dispersed as the direction of tearing changes periodically. As a result, the tearing of the outer film 2 and inner film 3 progresses along the grooves 21 and 31, as shown in the embodiment. This prevents the tearing from deviating from the grooves, causing the separation points of the outer film 2 and inner film 3 to not align, or preventing the outer film 2 and inner film 3 from being completely separated and leaving parts connected, thus mitigating the problem of not being able to properly unpack the packaging.

[0069] <Embodiment 2> This embodiment differs from Embodiment 1 in that the inner film 3 is composed of two inner film pieces 3a, 3a, as shown in Figures 20 to 26. Components common to Embodiment 1 are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0070] <Outer Film 2> The outer film 2 can be rectangular. The thickness (film thickness) H1 (see Figure 23) of the outer film 2 is preferably 10 to 40 μm.

[0071] As shown in Figure 23, the outer film 2 has an outer groove 21 that can be easily torn when unpacking. On both sides of this outer groove 21, there are raised outer edges 22 that are higher than the surface of the outer film 2.

[0072] The outer groove 21, with outer embankment sections 22 formed on both sides, can be formed, for example, by irradiating the outer film 2 with a laser beam. Figure 23 is an enlarged view of the outer groove 21 formed on the outer film 2 by laser processing.

[0073] The outer groove 21 can be formed along the entire length of the outer film 2, similar to Embodiment 1, when the rice ball 5 is packaged, so as to follow the line connecting one vertex of the rice ball 5 to the center of the opposite side. The appearance of the packaged rice ball 6, in which the rice ball 5 is packaged, is the same as in Embodiment 1, so please refer to Figures 6 and 7.

[0074] The outer groove 21 is preferably formed such that the thickness I1 of the outer film 2 in the portion where the outer groove 21 is formed (groove film thickness) is about 1 / 4 to 3 / 4 of the film thickness H1, as shown in Figure 23. Specifically, the groove film thickness I1 is 5 μm to 30 μm, preferably 10 μm to 25 μm.

[0075] Furthermore, the height L1 of the outer embankment 22 (embankment height) is preferably about 3 μm to 30 μm, and most preferably 5 μm to 15 μm.

[0076] It is preferable that the outer groove 21 be formed on the inner surface 24 facing the sheet-like food 4, as shown in Figure 24, which is an enlarged view of the circled area B in Figure 22.

[0077] <Inner Film 3> As shown in Figure 20, the inner film 3 of this embodiment can be composed of two inner film pieces 3a, 3a. As shown in Figure 22, the inner film pieces 3a, 3a are arranged so that their inner ends 3b, 3b overlap each other. It is preferable that the overlapping portion 3c of the inner ends 3b, 3b is configured to face the outer groove 21 of the outer film 2.

[0078] In this embodiment, the width of the overlapping portion 3c of the inner film pieces 3a, 3a is approximately 1 cm, and its length in the longitudinal direction is the same as that of the outer film 2.

[0079] The inner film 3 is composed of two inner film pieces 3a, 3a, but the inner film 3 may employ other known configurations.

[0080] <Packaging Sheet 1> As shown in Figure 20, the outer film 2, sheet-shaped food 4, and inner film 3 are assembled by overlapping the inner ends 3b, 3b of the inner film pieces 3a, 3a, placing the sheet-shaped food 4 approximately in the center of the inner surface of the inner film 3, and then placing the outer film 2 on top. Then, as shown in Figures 21 and 22, the outer film 2 and inner film 3 are heat-sealed 11 to surround the outer periphery of the sheet-shaped food 4, thereby creating the packaging sheet 1. It is desirable not to heat-seal the overlapping portion 3c so that the inner film pieces 3a, 3a can be easily separated from each other. In the illustration, the heat-sealed portion 11 is formed along the entire length in the longitudinal direction of the packaging sheet 1, and partially in the short direction to avoid the overlapping portion 3c of the inner film 3.

[0081] <How to unwrap the packaged rice ball 6> To unwrap the packaged rice ball 6, pinch the outer film 2 and pull it outwards with both hands, approximately perpendicular to the outer groove 21, as shown by arrow C in Figure 6.

[0082] When the outer film 2 is pulled, it tears starting from the outer groove 21, where the film thickness is thin. The outer groove 21 is reinforced by outer embankment portions 22 formed on both sides. Therefore, the tear line of the film does not deviate from the outer groove 21, but progresses along the outer groove 21, and the outer film 2 is completely torn and separated.

[0083] Furthermore, when the outer film 2 is pulled outward, the inner film 3 is pulled as the inner film pieces 3a, 3a slide between the rice ball 5 and the sheet-like food 4, causing the overlapping portion 3c to unravel and separate.

[0084] Compared to Embodiment 1 (where there is one inner film), this second embodiment has the advantage of being easier to manufacture because it does not require laser processing (inner groove 31, inner bank portion 32) on the inner film.

[0085] <Laser Processing and Method for Manufacturing Packaging Sheet 1> For manufacturing the packaging sheet 1 of this embodiment, the packaging sheet manufacturing apparatus 7 shown in Figure 25 can be used. The packaging sheet manufacturing apparatus 7 includes a laser irradiation unit 28.

[0086] The packaging sheet manufacturing apparatus 7 sandwiches a sheet of food 4 between a long outer film strip 20 and a pair of inner film strips 30, applies heat sealing 11, and cuts it to a predetermined length to manufacture a packaging sheet 1.

[0087] Since Figure 25 is a side view, only one of the inner film strips 30 from which the inner film pieces 3a, 3a are drawn is shown. However, in the front-to-back direction of the paper, a pair of inner film strips 30 are wound around a pair of inner film rolls 35, and emerge with their inner ends overlapping after passing through rollers 36, 37, etc. Then, sheet-like food products 4 are placed at predetermined intervals on the inner surface of the inner film strip 30 and move downstream together with the inner film strip 30.

[0088] The outer film strip 20 is pulled out from the outer film roll 25, and an outer groove 21 is formed by a laser irradiation unit 28 positioned between rollers 26 and 27. The laser irradiation unit 28 uses CO ２ An example can be provided of a unit that irradiates with a laser as a laser beam 28b.

[0089] The outer film strip 20, on which the outer groove 21 is formed, travels with its direction of travel changed horizontally by the roller 27. Then, as it travels horizontally, it covers the inner film strip 30 on which the sheet-like food 4 is placed, and travels downstream with the sheet-like food 4 sandwiched between the outer film strip 20 and the inner film strip 30.

[0090] Next, the outer film strip 20 and inner film strip 30, which sandwich the sheet-like food 4, enter the sealing device 71 located downstream. The sealing device 71 heat-seals 11 the outer film strip 20 and the inner film strip 30. It is desirable that the heat-sealing 11 is formed along the entire length in the longitudinal direction of the packaging sheet 1, and partially formed in the short direction so as to avoid the overlapping portion 3c of the inner film 3.

[0091] The heat-sealed outer film strip 20 and inner film strip 30 are then transported to the cutting device 74. The cutting device 74 cuts the outer film strip 20 and inner film strip 30 at approximately the midpoint of the heat-sealed area between the sheet-like food products 4, 4. This allows the packaging sheet 1 shown in Figure 21, etc., to be obtained.

[0092] <Different Embodiments of the Outer Groove 21> In Figure 21, etc., the outer groove 21 is formed in a straight line, but it may also be wavy as shown in Figure 26, or jagged, although not shown. By forming the outer groove 21 and outer embankment portion 22 in a wavy or jagged shape, the outer film 2 can be torn more easily compared to a straight line, and the packaging of the packaged rice ball 6 can be opened more easily.

[0093] Films were prepared with grooves having a raised edge (inventive example) and grooves without a raised edge (comparative example), and evaluated.

[0094] <Example 1: Observation of groove shape> Film: OPP film (stretched polypropylene film) with a thickness of 25 μm Invention example: CO2 with an output of 20 W and a wavelength of 10 μm ２ A laser was used, and the laser was directed at a speed of 15-25 m / min. Comparative example: A groove was formed using a cutter (rotary circular blade).

[0095] For the films of the inventive example and comparative example, a 3D profile and height graph were obtained using a digital microscope with respect to the measurement line passing through the groove. The results are shown in Figures 10 and 11.

[0096] Figures 10(a) and 10(b) show the shape measurement results of the film of the invention example. Referring to the figures, raised embankments were formed on both sides of the groove indicated by reference numeral 3, as indicated by reference numerals 1 and 2, which were higher than the film surface. More specifically, the height of the embankment in Figure 10(a) was approximately 3 μm, the height of the embankment in (b) was approximately 9 μm, and the height of the embankment in (c) was approximately 20 μm.

[0097] Figures 11(a) and (b) show the shape measurement results of the comparative example film. Referring to the figures, it can be confirmed that grooves were formed, but no raised embankments were formed that were higher than the film surface.

[0098] <Example 2: Film Cutting Test> An outer film was prepared: an OPP film (stretched polypropylene film) with a thickness of 25 μm. An inner film was prepared: an OPP film (stretched polypropylene film) with a thickness of 25 μm. Grooves 21 and 31 were formed in each film using laser processing (inventive example) and a cutter (comparative example), respectively, and the films were actually cut and compared. The groove depth (corresponding to K1 and K2 in Figure 4) was approximately 12.5 μm, and the height of the ridge portion in the inventive example (L1 and L2 in Figure 4) was approximately 7 μm.

[0099] In both the inventive example and the comparative example, eight outer films and eight inner films were prepared, with straight grooves formed on four films and wavy grooves on four films. The processing conditions for the grooves were the same as in Example 1. In the inventive example, the grooves were straight for approximately 2 cm to 3 cm of the film edge, while in the comparative example, no grooves were formed for approximately 2 cm to 3 cm of the edge.

[0100] The outer film and inner film of the obtained inventive example, and the outer film and inner film of the comparative example were pulled in the direction perpendicular to the groove, in this embodiment, by grasping both ends of the center in the longitudinal direction, and pulling in the short direction, and photographs of the film after breakage were taken. The results are shown in Figures 12 to 19. Figure 12 shows the outer film of the inventive example with a straight groove, Figure 13 shows the inner film of the inventive example with a straight groove, Figure 14 shows the outer film of the inventive example with a wavy groove, and Figure 15 shows the inner film of the inventive example with a wavy groove. Also, Figure 16 shows the outer film of the comparative example with a straight groove, Figure 17 shows the inner film of the comparative example with a straight groove, Figure 18 shows the outer film of the comparative example with a wavy groove, and Figure 19 shows the inner film of the comparative example with a wavy groove.

[0101] Referring to Figures 12-15, both the outer and inner films of the invention could be separated along straight and wavy grooves, respectively. This is because the embankment reinforced both sides of the groove, allowing the fracture to proceed without deviation.

[0102] On the other hand, referring to Figures 16 to 19, both the outer and inner films of the comparative example deviated from the groove and fractured.

[0103] These results confirm that by forming a groove with a raised edge, the tearing line progresses along the groove, allowing the film to be divided.

[0104] The results of this embodiment are applicable to any embodiment of the present invention. Specifically, the good separation results of the outer film (inventive example, Figures 12 and 14) shown in Embodiment 2 can be directly applied to the outer film 2 of Embodiment 2 (a configuration in which the inner film consists of two inner film pieces 3a). Furthermore, the separation results of the outer film and inner film (inventive example, Figures 12 to 15) can be applied to Embodiment 1 (a configuration in which the inner film has one inner groove 31).

[0105] The above description is for the purpose of explaining the present invention and should not be interpreted as limiting or restricting the scope of the invention described in the claims. Furthermore, it goes without saying that the configuration of each part of the present invention is not limited to the above embodiments and can be modified in various ways within the technical scope described in the claims.

[0106] For example, although the above description refers to a rice ball-shaped rice ball 5 wrapped in a rice ball-shaped packaging sheet 1, the packaging sheet 1 can also be used as a packaging sheet for rolled sushi that wraps cylindrical stick-shaped rice, or as a packaging sheet for hand-rolled sushi that wraps cone-shaped rice.

[0107] 1 Rice ball packaging sheet 11 Heat sealing 2 Outer film 3 Inner film 3a Inner film piece 3b Inner edge 3c Overlapping portion 4 Sheet-shaped food (sheet-shaped seaweed) 41 Surface (sheet-shaped food) 42 Back (sheet-shaped food) 43 Sheet-shaped food storage 44 Sheet-shaped food conveying means 5 Rice ball (food) 6 Packaged rice ball 7 Packaging sheet manufacturing device 20 Outer film strip 21 Outer groove 22 Outer edge 23 Outer surface (outer film) 24 Inner surface (outer film) 25 Outer film roll 26, 27 Rollers 28 Laser irradiation unit 29 Guide stand 30 Inner film strip 31 Inner groove 32 Inner edge 33 Inner surface (inner film) 34 Inner surface (inner film) 35 Inner film roll 36, 37 Rollers 38 Laser irradiation unit 39 Guide stand 71 Sealing device 72, 73 Heat sealing roller 74 Cutting device 75 Movable blade 76 Fixed blade 77 Packaging sheet conveying means H1, H2 Film thickness I1, I2 Groove film thickness J1, J2 Groove depth (including ridge) K1, K2 Groove depth L1, L2 Ridge height M1, M2 Ridge film thickness

Claims

1. An onigiri packaging sheet comprising: an outer film; an inner film placed on top of the outer film; and a sheet-like food sandwiched between the outer film and the inner film, wherein the outer film and the inner film are heat-sealed together at the outer circumference of the sheet-like food, the outer film having an outer groove formed by laser processing that is recessed from the surface of the outer film, and outer edges that are raised from the surface of the outer film are formed on both sides of the outer groove.

2. The rice ball packaging sheet according to claim 1, wherein the inner film consists of two inner film pieces, and the inner ends of the inner film pieces overlap at a position facing the outer groove.

3. The inner film is made of a single film, the inner film has an inner groove formed by laser processing that is recessed from the surface of the inner film, and on both sides of the inner groove, there are inner ridges that are raised from the surface of the inner film, the rice ball packaging sheet according to claim 1.

4. The groove film thickness I1 of the outer film in the portion where the outer groove is formed is 1 / 4 to 3 / 4 of the outer film thickness H1, as described in claim 1.

5. The rice ball packaging sheet according to claim 4, wherein the thickness H1 of the outer film is 10 μm to 40 μm, the groove film thickness I1 of the outer film in the portion where the outer groove is formed is 5 μm to 30 μm, and the height L1 of the outer edge portion from the surface of the outer film is 3 μm to 30 μm.

6. The groove film thickness I2 of the inner film in the portion where the inner groove is formed is 1 / 4 to 3 / 4 of the inner film thickness H2, the inner film thickness H2 is 10 μm to 40 μm, the groove film thickness I2 of the inner film in the portion where the inner groove is formed is 5 μm to 30 μm, and the height L2 of the inner bank from the surface of the inner film is 3 μm to 30 μm, as described in claim 3.

7. The rice ball packaging sheet according to claim 1, wherein the outer film has the outer groove and the outer edge formed on the inner surface of the sheet-like food side.

8. The inner film is an onigiri packaging sheet according to claim 3, wherein the inner groove and the inner bank portion are formed on the inner surface opposite to the sheet-like food.

9. The rice ball packaging sheet according to claim 3, wherein the outer film and the inner film are heat-sealed together so as to completely surround the outer periphery of the sheet-like food.

10. A packaged rice ball, which is packaged using the rice ball packaging sheet described in any one of claims 1 to 9.

Images