Rice ball packaging sheet and packaged rice ball

Abstract

This invention provides a rice ball packaging sheet that can be easily unpacked. [Solution] The rice ball food packaging sheet 1 of the present invention comprises an outer film 2, an inner film 3 arranged on top of the outer film and separable into left and right halves, and a sheet-like food 4 sandwiched between the outer film and the inner film, wherein the outer film and the inner film are heat-sealed to the outer circumference of the sheet-like food, and the outer film has an outer groove 21 formed by laser processing which is recessed from the surface of the outer film, and outer edges 22 which are raised from the surface of the outer film are formed on both sides of the outer groove.

Description

Technical Field

[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 a rice ball, and a packaged rice ball obtained by packaging a rice ball with the rice ball packaging sheet.

Background Art

[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 a sheet-shaped nori seaweed between an outer film and an inner film is widely known. Hereinafter, a packaging sheet for packaging a rice ball will be described as an example.

[0003] A cut tape for dividing the outer film is attached to the center in the width direction of the outer film, and the inner film consists of two inner film pieces. A sheet-shaped nori seaweed is sandwiched between the outer film and the inner film piece, 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 packaged with the above packaging sheet, after pulling the start end of the division of the cut tape to divide the outer film into two, by pulling one of the outer films outward, the inner film piece is 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 seaweed-wrapped rice ball in which the sheet-shaped nori seaweed is directly wound around the rice ball can be obtained and eaten.

[0006] Furthermore, Patent Document 3 discloses a rice ball packaging sheet in which groove-shaped half-cuts are formed in the center of the width direction of both the outer film and the inner film. When a rice ball is wrapped in this rice ball packaging sheet, the packaging can be opened by pulling the outer film and inner film in a direction perpendicular to the half-cuts, which separates the half-cuts. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2002-101832 [Patent Document 2] Japanese Utility Model Publication No. 6-8284 [Patent Document 3] Japanese Patent Publication No. 2008-100741 [Overview of the project] [Problems that the invention aims to solve]

[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 the rice ball. 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] 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.

[0010] The objective of the present invention is to provide a rice ball packaging sheet that can be easily unpacked. [Means for solving the problem]

[0011] The rice ball food packaging sheet of the present invention is Outer film and An inner film, which is placed on top of the outer film and can be separated into left and right halves, A sheet-like food sandwiched between the outer film and the inner film, Includes, An onigiri packaging sheet formed by heat-sealing the outer film and the inner film around the outer circumference of the sheet-like food, The outer film has an outer groove formed by laser processing that is recessed from the surface of the outer film. On both sides of the outer groove, an outer embankment portion is formed that is raised higher than the surface of the outer film.

[0012] The groove 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.

[0013] 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. The height L1 of the outer embankment portion from the surface of the outer film is preferably 3 μm to 30 μm.

[0014] Preferably, the outer film has the outer groove and outer edge formed on the inner surface of the sheet-like food side.

[0015] 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.

[0016] The packaged rice ball of the present invention is made by packaging a rice ball with the rice ball packaging sheet described above. [Advantages of the Invention]

[0017] The rice ball packaging sheet according to the present invention has outer grooves formed in an outer film, and outer ridge portions higher than the surface of the outer film are formed on both sides of the outer grooves. By being formed on the outer ridge portions, the thickness of the outer film is increased at these portions, reinforcing both sides of the outer grooves.

[0018] When the outer film is pulled outward in the left - right direction substantially orthogonal to the outer grooves, the outer film is divided starting from the thin outer grooves. In the present invention, both sides of the outer grooves are reinforced by the outer ridge portions. Therefore, the tearing line of the outer film is guided to the outer grooves and proceeds along the outer grooves without deviation. As a result, for the packaged rice ball formed by packaging the rice ball with the rice ball packaging sheet, by simply pulling the outer film and the inner film outward, the breakage progresses along the outer grooves and the outer film is divided, and the packaging can be easily opened.

[0019] Also, in the case of a rice ball packaging sheet using a cut tape, the three parts of the outer film, the inner film divided left and right, and the outer film with the cut tape adhered thereto become pieces of garbage. However, in the rice ball packaging sheet of the present invention, there are only two film masses of the outer film and the inner film divided left and right, and the number of garbage can be reduced. [Brief Description of the Drawings]

[0020] [Figure 1] FIG. 1 is an exploded perspective view of a rice ball packaging sheet according to the present invention. <� [Figure 2] FIG. 2 is a plan view of a rice ball packaging sheet according to the present invention. [Figure 3] FIG. 3 is a cross - sectional view taken along line A - A of FIG. 2. [Figure 4] FIG. 4 is a cross - sectional view in a direction orthogonal to the outer grooves of the outer film. [Figure 5] FIG. 5 is an enlarged view of the circled portion B in FIG. 3. [Figure 6]Figure 6 is a perspective view of a packaged rice ball, which is a rice ball wrapped in a packaging sheet. [Figure 7] Figure 7 is a perspective view of a packaged rice ball, seen from the back. [Figure 8] Figure 8 is a schematic diagram of the main components of a packaging sheet manufacturing apparatus. [Figure 9] Figure 9 is an exploded perspective view of another pattern of the packaging sheet according to the present invention. [Figure 10] Figure 10 shows the shape measurement results of the film of the invention example using a digital microscope. [Figure 11] Figure 11 shows the shape measurement results of the comparative example film using a digital microscope. [Figure 12] Figure 12 is a photograph of the outer film of the invention example with straight grooves formed after it has been cut. [Figure 13] Figure 13 is a photograph of the outer film of the invention example with a wavy groove formed after it has been cut. [Figure 14] Figure 14 is a photograph of the outer film of a comparative example in which straight grooves were formed, after it was cut. [Figure 15] Figure 15 is a photograph of the outer film of a comparative example that formed a wavy groove after being cut. [Modes for carrying out the invention]

[0021] The rice ball packaging sheet 1 of the present invention will be described below with reference to the drawings.

[0022] As shown in Figure 1, the rice ball packaging sheet 1 of the present invention consists 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 at multiple locations so as to surround the outer circumference of the sheet-like food 4, and are integrated to form the packaging sheet 1. In the illustrated embodiment, the outer film 2 consists of one film, and the inner film 3 consists of two inner film pieces 3a, 3a.

[0023] <Outer film 2> The outer film 2 can be rectangular. In the illustrated embodiment, the outer film 2 is a rectangle approximately 23 cm long and 16 cm wide. The outer film 2 may also be polygonal in shape, such as by rounding off the corners.

[0024] The outer film 2 can be made from common materials used for packaging rice balls, such as polypropylene films (PP films) like CPP film (unoriented polypropylene film) or OPP film (oriented polypropylene film), or polyethylene films (PE films). The outer film 2 can be, for example, a transparent film, and the product name, ingredients, etc., can be printed on it as appropriate.

[0025] The thickness of the outer film 2 (film thickness) H1 (see Figure 4) is preferably 10 to 40 μm, and more preferably 20 to 30 μm. If the film thickness H1 is thinner than this, it will not have sufficient strength, and if the film thickness H1 is thicker than this, it may become difficult to wrap the rice ball 5 and will also lead to increased costs.

[0026] The outer film 2 has an outer groove 21 that allows it to be easily torn when the outer film 2 and inner film 3 are pulled to the left and right, as shown in Figure 4, when the packaging is opened. On both sides of this outer groove 21, there are outer edges 22 that are raised higher than the surface of the outer film 2.

[0027] The outer groove 21, with its outer embankment portions 22 formed on both sides, can be formed, for example, by irradiating the outer film 2 with a laser beam, although the manufacturing method is not limited. A specific embodiment of the laser processing will be described later, but Figure 4 is an enlarged view of the outer groove 21 formed on the outer film 2 by laser processing. As shown in the figure, it can be seen that a part of the surface of the outer film 2 melts and becomes thinner when irradiated with a laser. On both sides of the outer groove 21, some of the melted resin flows to the left and right, forming raised embankment portions 22.

[0028] As shown in Figures 6 and 7, the outer groove 21 can be formed along the entire length of the outer film 2, 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, this corresponds to approximately the center in the shorter direction of the outer film 2 and inner film 3, as shown in Figures 1 and 2. The shorter direction of films 2 and 3 is also referred to as the left-right direction. Of course, the outer groove 21 may also be formed in the longitudinal direction of the outer film 2, and the formation position is not limited to the center, but may be offset from the center. In this case, the left-right direction becomes the longitudinal direction.

[0029] 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 4, and more preferably 1 / 3 to 1 / 2. Specifically, the groove film thickness I1 is 5 μm to 30 μm, preferably 10 μm to 25 μm. If the groove film thickness I1 is thinner than this, the outer film 2 may tear during the production of the packaging sheet 1 or when packaging rice balls. On the other hand, if the groove film thickness I1 is thicker than this, the outer film 2 may not tear properly.

[0030] In the case of the groove film thickness I1 described above, as shown in Figure 4, the depth J1 of the outer groove 21 including the embankment portion 22 is 10 μm to 25 μm, preferably 15 to 20 μm. At this time, the groove depth K1 from the surface of the outer film 2 to the bottom of the outer groove 21 is 5 μm to 20 μm.

[0031] Furthermore, the height L1 of the outer embankment 22 (embankment height) is preferably about 3 μm to 30 μm, more preferably 3 μm to 20 μm, and most preferably 5 μm to 15 μm. The embankment 22 is 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 is divided. When the embankment height L1 is as described above, the embankment film thickness M1 in the part where the embankment 22 is formed will be M1 = H1 + L1, so in the case of the above film thickness, the embankment film thickness M1 will be 13 μm to 70 μm.

[0032] The outer groove 21 may be formed on either surface of the outer film 2. 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.

[0033] On the other hand, as shown in Figure 5, which is an enlarged view of the circled area B in Figure 3, it is preferable that the outer groove 21 formed on the outer film 2 be formed on the inner surface 24 that faces the sheet-like food 4. This is because, with respect to the packaging sheet 1, if there is a raised outer edge 22 on the outer surface 23 of the outer film 2, purchasers and others may feel uncomfortable when they touch it.

[0034] <Inner film 3> The inner film 3 is positioned inside the outer film 2, sandwiching the sheet-like food 4. The inner film 3 can be composed of two inner film pieces 3a, 3a. As shown in Figure 3, the inner film pieces 3a, 3a are arranged so that their inner ends 3b, 3b overlap. It is preferable that the overlapping portion 3c of the inner ends 3b, 3b faces the outer groove 21 of the outer film 2.

[0035] 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.

[0036] The inner film 3 is composed of two inner film pieces 3a, 3a, but the inner film 3 may employ other known configurations.

[0037] The inner film 3 can also be made from common materials used for rice ball packaging sheets, such as polypropylene films (PP films) like CPP film (unoriented polypropylene film) or OPP film (oriented polypropylene film), or polyethylene films (PE films). The inner film 3 can be made from a transparent or opaque film.

[0038] The thickness of the inner film 3 (film thickness) is preferably 10 to 40 μm, and more preferably 20 to 30 μm. If the film thickness is thinner than this, it will not have sufficient strength, and if the film thickness is thicker than this, it may be difficult to wrap the rice ball 5 and will also lead to increased costs.

[0039] <Sheet-shaped food 4> The sheet-like food 4 sandwiched between the outer film 2 and the inner film 3 can be exemplified by sheet-like seaweed. The sheet-like food 4 can be roughly rectangular, but it can also be rectangular with beveled corners or with rounded corners. In the illustrated embodiment, the sheet-like 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-like food 4 is not limited to sheet-shaped seaweed; any thin food can be used, such as thinly rolled dried squid or kelp formed into a sheet.

[0041] <Packaging Sheet 1> As shown in Figure 1, the outer film 2, sheet-like 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-like 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 2 and 3, the outer film 2 and inner film 3 are heat-sealed 11 to surround the outer periphery of the sheet-like 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.

[0042] Since the outer film 2 of the packaging sheet 1 can be separated by the outer groove 21, cutting tape is not required. Furthermore, because the outer film 2 has no overlapping parts or perforations that allow moisture to enter, moisture can also be prevented from entering through the outer film 2.

[0043] <5 rice balls> The rice ball 5, which is wrapped in the above-mentioned packaging sheet 1, can be made by solidifying white rice or mixed rice into a flattened or spherical mass of rice, or into a round or rectangular prism-shaped stick of rice. The rice ball 5 may be partially or entirely sprinkled with a topping such as sesame seeds, or ingredients may be placed on top, or ingredients may be sandwiched inside. In this embodiment, as shown in Figures 6 and 7, the rice ball 5 is triangular and flattened, but it can also be made into a round or square rice ball.

[0044] <6 packaged rice balls> The rice ball 5 is wrapped in the packaging sheet 1 with the above configuration to become a packaged rice ball 6. The rice ball 5 is packaged by placing the packaging sheet 1 with the inner film 3 facing upwards onto the rice ball 5, and then covering it with the packaging sheet 1 so as to wrap around the rice ball 5, as shown in Figures 6 and 7. The overlapping parts of the packaging sheet 1 are then secured with fastening means such as tape or heat sealing (not shown) to obtain the packaged rice ball 6.

[0045] <How to unwrap a packaged rice ball (size 6)> To unwrap the rice ball 6 described above, pinch the outer film 2 and pull it with both hands outward (left and right in the diagram) approximately perpendicular to the outer groove 21, as shown by arrow C in Figure 6. This will pull the outer film 2, and at the same time as pulling the outer film 2, the inner film 3 inside will also be pulled.

[0046] The outer film 2 has a groove thickness I1 in the outer groove 21 that is thinner than the outer film 2 and its total film thickness H1. Therefore, when the outer film 2 is pulled, it tears starting from the outer groove 21 where the film thickness is thinner. The starting point of the tear is the outer groove 21 located on the bottom surface of the packaged rice ball 6. If the outer film 2 is pulled further to the left and right from this state, the tearing of the outer film 2 will progress. The outer groove 21 has outer embankment portions 22 formed on both sides. The film thickness M1 of the embankment portions is reinforced to be thicker than the groove film thickness I1, as shown in Figure 4. 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.

[0047] 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.

[0048] This allows the sheet-like food 4 to be pulled out from between the separated outer film 2 and inner film 3, resulting in a nori-wrapped rice ball 5 in which the rice ball 5 is wrapped in the sheet-like food 4.

[0049] In this invention, as described above, the rupture of the outer film 2 progresses along the outer groove 21, which prevents the rupture from deviating from the outer groove 21. It also prevents the outer film 2 from being completely separated and remaining partially connected, thereby mitigating the problem of being unable to properly unpack the packaging.

[0050] Furthermore, since the outer film 2 of the rice ball packaging sheet 1 of the present invention is a single film with no gaps such as perforations, moisture penetration through the outer film 2 can be prevented.

[0051] According to the present invention, to unwrap 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 unwrap the packaged rice ball 6. Furthermore, after unwrapping, 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.

[0052] <Laser processing and manufacturing method of packaging sheet 1> For laser processing of the outer groove 21 on the outer film 2 and manufacturing the packaging sheet 1, the packaging sheet manufacturing apparatus 7 shown in Figure 8 can be used. In the present invention, the packaging sheet manufacturing apparatus 7 includes a laser irradiation unit 28.

[0053] 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 pair of inner film strips 30 that are narrower than the outer film strip 20, applying heat welding 11 to the inner film strips 30 which overlap the inner ends of the outer film strip 20, and cutting to a predetermined length. Note that the outer film strip 20 and the inner film strips 30 may be arranged upside down.

[0054] 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.

[0055] Since Figure 8 is a side view, only one of the inner film strips 30 that pull out the inner film pieces 3a, 3a is shown. However, a pair of inner film strips 30 are wound around a pair of inner film rolls 35 in the front-to-back direction of the paper, and appear downstream of the sheet-like food conveying means 44 with their inner ends overlapping, while changing direction via rollers 36, 37, etc. Then, the sheet-like food 4 is placed on the inner surface of the inner film strip 30 at predetermined intervals and moves downstream together with the inner film strip 30.

[0056] 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.

[0057] 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 outer film strip 20 with the laser beam 28b. 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.

[0058] The laser irradiation unit 28 can be exemplified as a unit that irradiates with a CO2 laser as the laser beam 28b, but the laser beam 28b is not limited to a CO2 laser. 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.

[0059] Furthermore, in order to stabilize the irradiation distance of the laser beam 28b with respect 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.

[0060] 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.

[0061] 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.

[0062] 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).

[0063] 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.

[0064] 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.

[0065] <Different embodiments of the outer groove 21> In Figure 2, etc., the outer groove 21 is formed in a straight line, but it may also be wavy as shown in Figure 9, or jagged, although not shown. Wavy or jagged outer grooves 21 can be formed by moving the head unit 28a that irradiates the laser beam 28b from side to side with respect to the running direction of the outer film strip 20. Even in this case, outer embankment portions 22 are formed on both sides of the outer groove 21 along the shape of the wavy or jagged groove 21. By forming the outer groove 21 and outer embankment portions 22 in a wavy or jagged shape, the outer film 2 can be torn more easily than in a straight line, and the packaging of the packaged rice ball 6 can be opened more easily. This is thought to be because, compared to a straight outer groove 21, stress tends to concentrate at the apex of the wavy or jagged outer groove 21 during tearing, allowing the starting point of the fracture to be formed with less force, and the resistance is dispersed as the direction of tearing progresses periodically. Even in this case, the tear line of the outer film 2 progresses along the groove 21, as shown in the embodiment, which prevents the tear from deviating from the outer groove 21 and prevents the outer film 2 from being completely separated but remaining connected in part, thereby mitigating the problem of not being able to properly unpack the packaging.

[0066] 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.

[0067] For example, the above description refers to a packaging sheet 1 for a rice ball 5, but the packaging sheet 1 can also be used as a packaging sheet for rolled sushi that wraps cylindrical or cone-shaped rice, or for hand-rolled sushi that wraps cone-shaped rice. In this case, if necessary, ear-shaped films to cover the ends of the cylindrical or cone-shaped rice can be attached to the packaging sheet separately by heat welding or the like. In this case, the packaged rice ball 6 becomes packaged rolled sushi or packaged hand-rolled sushi. [Examples]

[0068] <Example 1> Outer films were prepared with an outer groove having a raised embankment (inventive example) and an outer groove without a raised embankment (comparative example), and observed using a digital microscope.

[0069] The outer film used is as follows: Film: 25μm thick OPP film (stretched polypropylene film)

[0070] In the example invention, grooves were formed by laser processing, while in the comparative example, outer grooves were formed using a cutter (rotary circular blade). More specifically, in the example invention, a CO2 laser with an output of 20W and a wavelength of 10μm was used, and the laser was irradiated onto the outer film at a speed of 15-25m / min.

[0071] For the outer 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 outer groove. The results are shown in Figures 10 and 11.

[0072] Figures 10(a) and 10(b) show the shape measurement results of the outer film of the example of the invention. Referring to the figures, outer embankments were formed on both sides of the outer 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.

[0073] Figures 11(a) and (b) show the shape measurement results of the outer film of the comparative example. Referring to the figures, it can be confirmed that an outer groove was formed, but an outer embankment that was raised higher than the film surface was not formed.

[0074] <Example 2> Outer film: 25μm thick OPP film (stretched polypropylene film) The materials were prepared, and outer grooves were formed using laser processing (inventive example) and a cutter (comparative example). The materials were then actually cut and compared. The groove depth (corresponding to K1 in Figure 4) was approximately 12.5 μm, and the height of the outer embankment in the inventive example (L1 in Figure 4) was approximately 7 μm.

[0075] In both the inventive example and the comparative example, eight outer films were prepared, with straight outer grooves formed on four films and wavy outer grooves on four films. The processing conditions for the outer grooves were the same as in Example 1. In the inventive example, the outer grooves were straight for approximately 2-3 cm of the film edge, while in the comparative example, no outer grooves were formed for approximately 2-3 cm of the edge.

[0076] For the outer films of the obtained inventive example and comparative example, both ends of the center in the longitudinal direction (in this example, the longitudinal direction) were grasped in the direction perpendicular to the outer groove and pulled in the transverse direction, and photographs of the film after breakage were taken. The results are shown in Figures 12 to 15. Figure 12 shows the outer film of the inventive example with a straight groove, Figure 13 shows the outer film of the inventive example with a wavy groove, Figure 14 shows the outer film of the comparative example with a straight groove, and Figure 15 shows the outer film of the comparative example with a wavy groove.

[0077] Referring to Figures 12 and 13, the outer film of the invention example could be divided along both straight and wavy grooves. This is because the embankment reinforced both sides of the groove, allowing the tear line to proceed without deviation.

[0078] On the other hand, referring to Figures 14 and 15, the outer films of the comparative examples all deviated from the outer groove and fractured.

[0079] These results confirm that by forming an outer ditch with an outer embankment, the tear line progresses along the ditch, allowing the film to be divided. [Explanation of Symbols]

[0080] 1. Rice ball packaging sheet 11 Heat welding 2. Outer film 21 Exterior ditch 22 Outer embankment section 3. Inner film 3a Inner film piece 3b Inner end 3c Overlapping area 4. Sheet-shaped foods (sheet-shaped seaweed) 5 rice balls 6. Packaged rice balls

Claims

1. Outer film and An inner film, which is placed on top of the outer film and can be separated into left and right halves, A sheet-like food sandwiched between the outer film and the inner film, Includes, An onigiri packaging sheet formed by heat-sealing the outer film and the inner film around the outer circumference of the sheet-like food, The outer film has an outer groove formed by laser processing that is recessed from the surface of the outer film. On both sides of the outer groove, an outer embankment portion is formed that is raised higher than the surface of the outer film. 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 1 / 4 to 3 / 4 of the outer film thickness H1, and in the range of 5 μm to 30 μm. The outer embankment portion has a height L1 from the surface of the outer film of 3 μm to 30 μm. Rice ball packaging sheet.

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

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

4. The outer groove includes a curve in at least part of it. The rice ball packaging sheet according to claim 1.

5. A rice ball is packaged using the rice ball packaging sheet described in claim 1. Packaged rice balls.

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