Packaged product and its manufacturing method

Abstract

To prevent tearing of a film for collective packaging when a soft pack product is collectively packaged with the film.SOLUTION: There is provided a packaged product 6 that includes an individual package 4 in which a sheet bundle 3 in which a plurality of sheets are stacked is packaged with an individual packaging sheet 2, and an exterior film 5 in which a plurality of the individual packages 4 are packaged together. The individual packaging sheet 2 has a value of √TY, which is a geometric mean of a bending stiffness T in a MD direction and a bending stiffness Y in a CD direction, of 0.0014 to 0.0060 mN.m, and the exterior film 5 has a tear strength of 0.3 N or more.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a packaged product (aggregate package) in which a plurality of individually packaged items are packaged together, and a method for manufacturing the same. In particular, one of the features of the present invention is that the individually packaged items are soft pack products in which individual sheet bundles are individually packaged in individual packaging sheets. [Background technology]

[0002] BACKGROUND ART Conventionally, so-called soft pack products have been known, in which sanitary paper such as tissue paper is individually wrapped in an individual wrapping sheet such as a resin film (Patent Document 1).

[0003] Also known is an individual packaging machine that automatically packages a bundle of multiple articles into a packaging bag made of resin film or the like (Patent Document 2). This type of individual packaging machine is configured to open the opening of the packaging bag, and then, while maintaining the opened state of the packaging bag, push the multiple articles into the packaging bag through the opening.

[0004] Furthermore, a collective packaging machine for collectively packaging (packaging) a plurality of individually packaged items, each of which is a carton containing a bundle of sanitary paper, with a resin film or the like is also known (Patent Document 3). The collective packaging machine of Patent Document 4 aligns the orientation of a plurality of cartons and then packs the plurality of cartons with a resin film to obtain a packaged product in which, for example, five cartons are packed together. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-133981 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-125228 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-175667 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, with reference to the technologies of Patent Documents 1 to 3, it is conceivable to obtain soft-pack products by individually wrapping sanitary paper, and then further collectively package a plurality of these soft-pack products. In this case, when the soft-pack products are collectively packaged, the packaging materials come into contact with each other, and if the packaging material for the individual packaging is harder or stronger (stiffer) than the packaging material for the collective package, tears may occur in the packaging material for the collective package when the soft-pack products are collectively packaged.

[0007] Here, Patent Document 1 proposes that the bending stiffness of the individual packaging material be set to 20 to 330 μN·m in the MD direction and 8 to 145 μN·m in the CD direction, with the aim of making it easier to wrap sanitary paper stacks and making the overall soft-pack product compact after individual packaging. Thus, Patent Document 1 proposes optimizing the bending stiffness of the individual packaging material with the aim of improving the performance of the soft-pack product alone. However, Patent Document 1 does not consider how to prevent tearing of the collective packaging material when packaging multiple soft-pack products together.

[0008] Therefore, the main object of the present invention is to prevent tears from occurring in the outer packaging film for collective packaging when multiple soft pack products, each of which is made by individually wrapping a bundle of sheets such as a bundle of sanitary paper sheets in an individual packaging sheet, are bundled together and then collectively packaged in an outer packaging film. [Means for solving the problem]

[0009] The present invention relates to a packaged product (assembly package 6). The packaged product according to the present invention includes individual packages 4 and an exterior film 5. The individual packages 4 are individual sheet bundles 3, each of which is composed of a plurality of laminated sheets W, packaged in an individual packaging sheet 2. Such individual packages 4 are also referred to as soft-pack products. Examples of the individual packaging sheet 2 include polyethylene, polypropylene, polyester, paper, glassine paper, and composites thereof molded into a thin film. When using paper, the individual packaging sheet 2 may be a composite material laminated with a heat-sealable film, or the seal portion may be coated with a heat-sealable adhesive. The adhesive may be applied offline in advance or online during packaging. The exterior film 5 is used to package multiple individual packages 4 together. In the present invention, the individual packaging sheet 2 has a value of √TY, which is the geometric mean of the bending stiffness T in the MD and the bending stiffness Y in the CD, of 0.0014 to 0.0060 mN·m. The "MD direction" of a film or sheet refers to the machine direction (extrusion direction) during production, and the "CD direction" of a film or sheet refers to the direction perpendicular to this machine direction. Furthermore, in the present invention, the exterior film 5 used has a tear strength in the MD direction of 0.3 N or more. There is no particular upper limit to the tear strength of the exterior film 5, but it is preferably 3.5 N or less. Furthermore, it is preferable that the MD direction of the exterior film 5 coincides with the direction in which the individually packaged items 4 are inserted into the exterior film 5. In this way, by making the geometric mean of the bending stiffness of the individual packaging sheet 2 relatively flexible by being within the above-mentioned specified range, and by making the tear strength of the exterior film 5 relatively strong by being above the above-mentioned specified value, it is possible to prevent tearing of the exterior film 5 when packaging the individually packaged items 4 with the exterior film 5.

[0010] In the packaged product according to the present invention, the value of √TY of the individual wrapping sheet 2 is preferably 0.0050 mN·m or less. In particular, the value of √TY of the individual wrapping sheet 2 is preferably 0.0040 or less.

[0011] In the packaged product according to the present invention, the bending stiffness T of the individual wrapping sheet 2 is preferably 0.0018 to 0.0060 mN·m, and the bending stiffness Y of the individual wrapping sheet 2 is preferably 0.0020 to 0.0065 mN·m. 10. The packaging product of claim 1.

[0012] In the packaged product according to the present invention, the tear strength of the exterior film 5 is preferably 1N or more.

[0013] In the packaged product according to the present invention, the exterior insertion ratio of the individual packages 4 to the exterior film 5 is preferably 98 to 106%. The exterior insertion ratio is the inner perimeter of the exterior film 5 relative to the theoretical perimeter (100%) of the multiple individual packages 4 when inserted. By setting the exterior insertion ratio within the above-mentioned specified range, tearing of the exterior film 5 can be further suppressed, and the tightness when multiple individual packages 4 are packaged in the exterior film 5 can be improved (reduced looseness).

[0014] In the packaged product according to the present invention, the compression rate of the individual packages 4 is preferably 98 to 105%. By setting the compression rate of the individual packages 4 within the above-mentioned range, tearing of the packaging film 5 can be further suppressed.

[0015] In the packaged product according to the present invention, it is preferable that the coefficient of friction on the inner surface of the individual packaging sheet 2 is greater than the coefficient of friction on the outer surface. By using an individual packaging sheet 2 with a greater coefficient of friction on the inner surface, the sheet stack 3 can be easily wrapped in the individual packaging sheet 2, improving the tightness of the individual packages 4 and, in turn, improving the tightness of the final packaged product (collective package 6). [Effects of the Invention]

[0016] According to the present invention, when soft-pack products are collectively packaged with individual packaging sheets, tearing of the exterior film for collective packaging can be suppressed. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 shows a schematic diagram of a process in which a continuous sheet bundle, which is made by folding and stacking a plurality of continuous sheets, is individually cut to obtain a plurality of individual sheet bundles. [Figure 2] FIG. 2 shows an example of an interfolder for folding continuous sheets. [Figure 3] FIG. 3 is a cross-sectional view that schematically shows the process of folding the continuous sheet. [Figure 4] FIG. 4 is a cross-sectional view showing another example of a continuous sheet bundle. [Figure 5] FIG. 5 is a schematic diagram showing a process of collectively packaging the individually wrapped sheet bundles. [Figure 6] FIG. 6 is a cross-sectional view schematically showing the process of individually packaging individual sheet bundles. [Figure 7] FIG. 7 is a cross-sectional view schematically showing the process of individually packaging individual sheet bundles. [Figure 8] FIG. 8 shows a schematic structure of an individually wrapped individual sheet bundle. [Figure 9] FIG. 9 shows an example of a gusseted exterior film. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, but also includes appropriate modifications of the embodiments below within the scope obvious to those skilled in the art. In the present specification, unless otherwise specified, "A to B" means A or more and B or less.

[0019] FIG. 1 shows an example of a process for producing a packaged product according to one embodiment of the present invention, from the step of folding a continuous sheet W' to obtaining individual sheet bundles 3. In this embodiment, the continuous sheet W' is assumed to be a continuous web of general tissue paper (sanitary paper). The packaged product is assumed to be an individual package 4, in which individual sheet bundles 3 made of laminated tissue paper are individually wrapped in a resin film or the like, or a collective package 6, in which a plurality of such individual packages 4 are collectively wrapped (see FIGS. 1 and 5). Therefore, in the production method according to this embodiment, as shown in FIG. 1, first, the continuous sheet W' unwound from multiple sheet rolls (not shown) is folded and stacked in the thickness direction to obtain a continuous sheet bundle 3', and then the continuous sheet bundle 3' is cut at predetermined intervals to form the individual sheet bundles 3. As shown in FIG. 1, the process for producing such individual sheet bundles 3 is mainly performed by a folding mechanism 10, a cutting device 20, and a feeder device 30.

[0020] The folding mechanism 10 overlaps and folds continuous sheets W' delivered from multiple sheet rolls (not shown) to stack them in the thickness direction. A known folding mechanism 10 can be used. Specifically, the folding mechanism 10 includes a number of folding-plate interfolders 11 and a conveyor 12. Each interfolder 11 overlaps two continuous sheets W', then folds the continuous sheets W' using a folding plate to stack them one after another on the conveying surface of the conveyor 12. For example, to produce a sheet product in which 150 sets of two-ply tissue paper sheets (300 sheets in total) are stacked, 75 interfolders 11, each capable of producing two sets, can be installed in the flow direction. The conveyor 12 of the folding mechanism 10 transports the sheets folded by each interfolder 11 toward the downstream side of the device at a constant speed. The continuous sheets thus stacked by the folding mechanism 10 to a predetermined number are referred to herein as a continuous sheet bundle 3'.

[0021] FIG. 2 shows an example of the configuration of the interfolder 11. The configuration example of the interfolder 11 shown in FIG. 2 is well known. The interfolder 11 uses this folding plate structure to fold two continuous sheets W' and stack them on top of another continuous sheet W' below that being conveyed by the conveyor 12. For convenience of illustration, FIG. 2 omits some components of the interfolder 11 and illustrates a state in which two continuous sheets W' are not passing through the interfolder 11. As shown in FIG. 2, the interfolder 11 mainly includes an inner guide 11a, an outer guide 11b, and an upper pressure bar 11c. The inner guide 11a is used to fold the first continuous sheet W'1 of the two continuous sheets W'1 and W'2 upward. The outer guide 11b is used to fold the second continuous sheet W'2 of the two continuous sheets W'1 and W'2 downward. The outer guide 11b is divided into an upper portion 11b(1) and a lower portion 11b(2). In addition, an upper pressure bar 11c is provided on the inner guide 11a side, and by adjusting this upper pressure bar 11c, the first continuous sheet W'1 can be prevented from being folded at a position offset from the inner guide 11a, thereby stabilizing the folding position. The function of the interfolder 11 will be described in more detail with reference to Figure 3.

[0022] FIG. 3 schematically shows how the interfolder 11 folds the continuous sheet W'. As shown in FIG. 3(a), two continuous sheets W'1 and W'2 are introduced into the interfolder 11 in a partially overlapping state. At this time, of the two overlapping continuous sheets W'1 and W'2, the one located on the lower side is referred to as the first continuous sheet W'1, and the one located on the upper side is referred to as the second continuous sheet W'2. Note that in the drawings of the present application, for convenience, the first continuous sheet W'1 and the second continuous sheet W'2 are depicted with different hatching patterns, but they are essentially the same type of sanitary paper.

[0023] Next, as shown in FIG. 3(b), of the two overlapping continuous sheets W'1 and W'2, the lower first continuous sheet W'1 is folded upward, and its folded portion is placed on top of the second continuous sheet W'2. As a result, a portion of the second continuous sheet W'2 is sandwiched between the first continuous sheet W'1. When folding the first continuous sheet W'1 upward in this manner, the inner guide 11a and upper pressure bar 11c (see FIG. 2) of the interfolder 11 are used. That is, the inner guide 11a of the interfolder 11 is inserted into the inner side of the fold of the first continuous sheet W'1, and the first continuous sheet W'1 is folded upward along this inner guide 11a while being guided by the upper pressure bar 11c. At this time, the first continuous sheet W'1 embraces the inner guide 11a and a portion of the second continuous sheet W'2. By folding back the first continuous sheet W'1 using the inner guide 11a in this way, a crease is formed in the first continuous sheet W'1 along the inner guide 11a.

[0024] Next, the lower first continuous sheet W'1 is folded upward, and as shown in FIG. 3(c), the upper second continuous sheet W'2 is folded downward, with the folded portion placed beneath the first continuous sheet W'1. At this time, the second continuous sheet W'2 not only sandwiches the first continuous sheet W'1 introduced into the interfolder 11, but also a portion of another first continuous sheet W'1 (shown by the dotted line) that has already been folded by another interfolder 11 upstream. When folding the second continuous sheet W'2 downward, the outer guide 11b of the interfolder 11 is used. As shown in FIG. 2, this outer guide 11b is divided into an upper portion 11b(1) and a lower portion 11b(2). The outer guide 11b of the interfolder 11 is located on the outer side of the fold of the second continuous sheet W'2. The outer guide 11b has a portion that contacts the upper surface of the second continuous sheet W'2 and a portion that contacts the lower surface of the folded sheet W'2, with the fold of the second continuous sheet W'2 as the boundary, and has a cross-sectional shape that is roughly U-shaped when laid on its side. The second continuous sheet W'2 is folded downward when drawn into the roughly U-shaped outer guide 11b. The upper portion 11b(1) of the outer guide 11b guides the first continuous sheet W'1 and the second continuous sheet W'2 introduced into the interfolder 11 by pressing them from above, and the lower portion 11b(2) of the outer guide 11b guides the second continuous sheet W'2 and the underside of another first continuous sheet W'1 (dotted line) that has already been folded by another interfolder 11. In this way, the second continuous sheet W'2 is drawn into the outer guide 11b and folded downward along the outer guide 11b. By folding back the second continuous sheet W'2 using the outer guide 11b in this way, a crease is formed in the second continuous sheet W'2 along the outer guide 11b.

[0025] FIG. 3(d) shows a cross-sectional view of a continuous sheet bundle 3' formed by repeating the steps shown in FIGS. 3(a) to 3(c). In the continuous sheet bundle 3' formed by the above steps, each continuous sheet W'1, W'2 is folded approximately in half, and two overlapping continuous sheets are inserted between each continuous sheet. Therefore, the continuous sheet bundle 3' is integrated into a pop-up bundle, in which lifting one continuous sheet also lifts the continuous sheets below it. More specifically, as described above, by folding the continuous sheets using the interfolder 11, in the continuous sheet bundle 3', the fold of the first continuous sheet W'1, which is folded upward, is aligned with the first side surface S1, and the fold of the second continuous sheet W'2, which is folded downward, is aligned with the opposite second side surface S2. As mentioned above, the folding methods for the two continuous sheets W'1 and W'2 introduced together into the interfolder 11 are different: upward folding using the inner guide 11a and upper pressure bar 11c and downward folding using the outer guide 11b. The first continuous sheet W'1, which is folded upward using the inner guide 11a and upper pressure bar 11c, is relatively easy to align its folds toward the first side surface S1, while the second continuous sheet W'2, which is folded downward using the outer guide 11b, is relatively difficult to align its folds toward the second side surface S2. Because the folding position of the first continuous sheet W'1 is determined by the inner guide 11a, adjusting the position of the inner guide 11a of each interfolder 11 makes it possible to align the folding positions of each pair, and the upper pressure bar 11c can reduce variations in folding at the inner guide 11a. That is, the folding position of the first continuous sheet W'1 is more stable when it is sandwiched between the inner guide 11a and the upper pressure bar 11c. On the other hand, the outer guide 11b on the bottom folding side can only guide the sheet outward, so although the position can be adjusted, it is difficult to suppress variations and align the folding position. This difference is due to the structure of the inner guide 11a and outer guide 11b and the folding method described above.

[0026] The topmost layer of the continuous sheet bundle 3' is the first continuous sheet W'1 folded upward by the inner guide 11a. t The outer guide 11b of the second continuous sheet W'2 lies on the second side surface S2, that is, in the direction in which the folds of the second continuous sheet W'2 are aligned. On the other hand, the second continuous sheet W'2 is located at the bottom of the continuous sheet bundle 3' and has been folded downward by the outer guide 11b. The side edge E of the second continuous sheet W'2 at the bottom b faces the first side surface S1, that is, faces the direction in which the folds of the first continuous sheet W'1 are aligned.

[0027] 4(a) shows a modified example of the cross-sectional structure of the continuous sheet bundle 3' shown in FIG. 3. As shown in FIG. 4, the first continuous sheet W'1 in the top layer of the continuous sheet bundle 3' has its side edge E t In the example shown in FIG. 4, the side edge E of the top first continuous sheet W'1 may be folded back one or more times. t The side is further folded downward, and this folded portion is inserted between the topmost first continuous sheet W'1 and the second continuous sheet W'2 located below it. This makes it difficult for the topmost first continuous sheet W'1 to be turned up. Although not shown in the drawings, the side edge E of the topmost first continuous sheet W'1 t It is also possible to fold the side two or more times. t It is also possible to fold the side upward. Fig. 4(b) shows the cross-sectional structure of an individually packaged item 4 obtained by individually packaging individual sheet bundles 3, which are obtained by cutting the continuous sheet bundle 3' shown in Fig. 4(a) individually, with an individual packaging sheet 2. The method for individually packaging the individual sheet bundles 3 will be described in detail later.

[0028] Returning to FIG. 1 , a cutting device 20 is provided downstream of the folding mechanism 10. The cutting device 20 cuts the continuous sheet bundle 3′ formed by the folding mechanism 10 in the thickness direction at predetermined intervals to obtain individual sheet bundles 3 of predetermined dimensions. For example, when producing tissue paper, the continuous sheet bundle 3′ is cut at intervals of 140 to 260 mm. This results in individual sheet bundles 3 of approximately the same length. Specifically, as shown in FIG. 1 , the cutting device 20 includes a cutter 21 and a conveyor 22. The cutter 21 cuts the continuous sheet bundle 3′ in the thickness direction to form individual sheet bundles 3. The cutter 21 is equipped with, for example, multiple circular blades, and uses the multiple blades to continuously cut the continuous sheet bundle 3′ at high speed. The conveyor 22 transports the individual sheet bundles 3 obtained by cutting with the cutter 21 downstream. Although omitted in the example shown in Figure 1, in addition to the conveyor 22 that contacts the lower surface of the individual sheet stack 3, another conveyor (not shown) that contacts the upper surface of this individual sheet stack 3 may be provided, and the individual sheet stack 3 may be transported while being sandwiched between the upper and lower conveyors.

[0029] The individual sheet stack 3 is made up of multiple sheets W (sanitary paper) stacked in the thickness direction. In the individual sheet stack 3, each sheet W is folded roughly in half, and between each sheet W, halves of two other sheets W that overlap above and below it are inserted. For this reason, the individual sheet stack 3 is integrated into a bundle in a pop-up manner, whereby when a sheet W is lifted up, the sheets W below it are also lifted up.

[0030] The carry-in device 30 is disposed downstream of the cutting device 20 primarily for the purpose of adjusting the spacing between the individual sheet bundles 3. As described above, when the continuous sheet bundle 3' is cut by the cutting device 20, individual sheet bundles 3 are obtained. However, these individual sheet bundles 3 are conveyed in a continuous line with almost no gaps between them on the conveyor 22 of the cutting device 20. If there are no gaps between the individual sheet bundles 3, it becomes difficult to mechanically rotate the individual sheet bundles 3 or individually package them in subsequent processes. Therefore, the carry-in device 30 widens the spacing between the individual sheet bundles 3 and adjusts the spacing between the individual sheet bundles 3 so that they are even. In this case, the carry-in device 30 basically starts conveying the individual sheet bundles 3 at a speed faster than the conveyor 22 of the cutting device 20. This widens the spacing between the individual sheet bundles 3 on the carry-in device 30. For this reason, the carry-in device 30 is also referred to as a speed-up conveyor.

[0031] The carry-in device 30 includes a lower conveyor 31 and an upper conveyor 32. The lower conveyor 31 contacts the bottom sheet of the individual sheet stack 3 and conveys the individual sheet stack 3 downstream. The upper conveyor 32 contacts the top sheet of the individual sheet stack 3 and conveys the individual sheet stack 3 downstream. In this manner, the individual sheet stack 3 is temporarily sandwiched between the lower conveyor 31 and the upper conveyor 32 and sent downstream. Note that, as shown in FIG. 1 , the conveying surface of the lower conveyor 31 for the individual sheet stack 3 extends further downstream than the upper conveyor 32. For this reason, the section in which the individual sheet stack 3 is sandwiched between the lower conveyor 31 and the upper conveyor 32 and conveyed is only temporary, and when the sandwiching between the lower conveyor 31 and the upper conveyor 32 is released, the individual sheet stack 3 is conveyed only by the lower conveyor 31. As described above, the transport speed of the individual sheet bundles 3 by the lower conveyor 31 and the upper conveyor 32 is faster than the transport speed of the conveyor 22 of the cutting device 20. Therefore, as shown in Fig. 1, the spaces between the individual sheet bundles 3 widen when the individual sheet bundles 3 are transferred from the conveyor 22 of the cutting device 20 to the lower conveyor 31 and the upper conveyor 32. Also, because the transport speeds of the lower conveyor 31 and the upper conveyor 32 are constant, the spaces between the individual sheet bundles 3 are adjusted to be approximately uniform.

[0032] Figure 5 shows the process subsequent to Figure 1. Specifically, Figure 5 shows a schematic example of a series of processes from the introduction of the individual sheet bundles 3 to the removal of the collective package 6, that is, a carry-in process, an individual packaging process, a conveying process, a collective packaging process, and a carry-out process. Note that Figure 5 conceptualizes and simplifies each process to clearly show this series of processes, and does not reproduce the actual process.

[0033] As shown in FIG. 5 , in the carrying-in process, the carrying-in device 30 described above carries a plurality of individual sheet bundles 3 at intervals and introduces them into the individual packaging machine 40. As described above, in the example shown in FIG. 5 , the individual sheet bundles 3 are assumed to be sanitary paper bundles. As shown in FIG. 5 , in the individual packaging process, the individual sheet bundles 3 are individually packaged by the individual packaging machine 40. At this time, a packaging roll 1 is supplied to the individual packaging machine 40. The packaging roll 1 is made up of a plurality of individual packaging sheets 2 connected in a continuous line and is usually wound in a roll shape. Note that in the example shown in FIG. 4 , the packaging roll 1 is made up of a plurality of individual packaging sheets 2 with a plurality of different designs (colors, variations, shapes) connected in a continuous line. For example, the packaging roll 1 is made up of individual packaging sheets 2 with two different designs connected alternately. Alternatively, the packaging roll 1 may be made up of, for example, three different designs connected in a repeated order of individual packaging sheets 2.

[0034] Such packaging roll 1 can be obtained by printing colors or patterns on a sheet such as a plain or white film using a known printer. Furthermore, the individual packaging sheet 2 (packaging roll 1) is preferably a flexible packaging film made of a resin such as polyethylene, polypropylene, polyvinyl chloride, polyester, or polyvinyl acetate. Among these, polyethylene is particularly preferred for the individual packaging sheet 2. If the film forming the individual packaging sheet 2 is made of a relatively hard material such as polypropylene, the corners of the individually packaged items 4 will come into contact with the exterior film 5, making the exterior film 5 more likely to tear and making it difficult to tightly package the items. For this reason, it is recommended to use a relatively soft film material such as polyethylene for the individual packaging sheet 2. Polyethylene has the lowest stiffness compared to other resins at the same thickness, making it low-cost, has the lowest risk of damaging the exterior bag, and produces a tighter package. Therefore, polyethylene is the most preferred material for the individual packaging. Note that even polypropylene, for example, becomes softer when the film is made thinner; therefore, the terms "relatively hard material" and "relatively soft material" used here refer to materials that are relatively hard or soft when compared at the same thickness. Furthermore, the individual wrapping sheet 2 (raw wrapping sheet 1) can also be made of paper. The paper material can be, for example, paper alone or a paper / resin film composite. In the case of paper alone, a material with heat-sealable glue applied to the sealing portions (the sealed portion of the wrapping and the folded-in portions on the sides) can be used, or paper alone can be coated with heat-sealable glue during the packaging process.

[0035] As an index of flexibility of the individual packaging sheet 2, the bending stiffness of the sheet may be set within a specific range. In the present specification, the bending stiffness of the individual packaging sheet 2 is represented by T, which is the bending stiffness value in the MD direction of the sheet, and Y, which is the bending stiffness value in the CD direction of the sheet. In this case, the bending stiffness T (MD direction) of the individual packaging sheet 2 is preferably 0.0014 to 0.0070 mN·m, more preferably 0.0018 to 0.0060 mN·m, and particularly preferably 0.0021 to 0.0054 mN·m. The bending stiffness Y (CD direction) of the individual packaging sheet 2 is preferably 0.0016 to 0.0075 mN·m, more preferably 0.0020 to 0.0065 mN·m, and particularly preferably 0.0023 to 0.0060 mN·m.

[0036] Furthermore, the bending stiffness of the individual wrapping sheet 2 is represented by √TY, which is the geometric mean of the T value (MD direction) and the Y value (CD direction). In this case, the bending stiffness √TY of the individual wrapping sheet 2 is preferably 0.0014 to 0.0060 mN·m, and particularly preferably 0.0022 to 0.0057 mN·m. The lower the value of √TY, the softer the individual wrapping sheet 2. For this reason, the value of √TY is preferably 0.0050 or less, and may be 0.0040 or less. There is no particular lower limit to the value of √TY, but it should be 0.0001 mN·m or more, and is preferably 0.0010 mN·m or 0.0014 mN·m or more.

[0037] In this way, by using a relatively soft film with little bending stiffness, particularly a polyethylene film, as the individual wrapping sheet 2, the outer wrapping film 5 is less likely to tear when a plurality of individually wrapped items 4 are collectively wrapped in the outer wrapping film 5.

[0038] The bending stiffness is determined by a method conforming to "Method for measuring deflection under its own weight, TAPPI UM409" described in "Paper and Pulp Testing Methods" (Paper and Pulp Technology Association).

[0039] More specifically, the bending stiffness of the individual wrapping sheet 2 is expressed by the following formula. [Formula] Bending stiffness (mN m) = (wL 4 / 8y)×9.81 where w is the basis weight (g / m 2 ), L is the bending length (m), and y is the degree of deflection (m). The degree of deflection y is measured as follows: [Measurement method] Prepare a sample piece of individually wrapped sheet 2 measuring 30 mm wide and 150 mm long, place this sample piece on a right-angled stand with the tip of the individually wrapped sheet 2 sticking out 30 mm (bending length L), hold the sample piece down on the stand to prevent it from floating, and measure the vertical length of the hanging tip (degree of deflection y).Measurements are taken at n=10 points on each side of the front and back of the individually wrapped sheet 2, and the average is taken as a total of 20 points.

[0040] Furthermore, the winding direction (winding flow direction) of the packaging roll 1 is preferably the short-edge direction of the individual packaging sheet 2 (i.e., the width direction of the individually packaged items 4). By aligning the short-edge direction of the individual packaging sheet 2 with the flow direction of the packaging roll 1, the length of each design in the flow direction of the packaging roll 1 can be reduced. Since the design is determined by the size of the printing roll of the printing equipment, a shorter design allows for a greater number of designs to be produced. Furthermore, since the pitch is short, more sheets can be produced with the same roll diameter, reducing the frequency of roll replacement. Furthermore, it is preferable that the packaging roll 1 not have a design printed on the heat-sealed portion during packaging. This non-printed portion increases the spacing between the individual packaging sheets 2, making it easier to cut the sheets between the individual packaging sheets 2. Even if printing is required, the sheet cutting area should have a blank area of ​​at least 4 mm, preferably at least 10 mm, or a design area that fits both designs. When printing the design on the packaging roll 1, a register mark (not shown) may also be printed. It is preferable to place the register mark on the heat-sealed part (cut surface) on the side, and furthermore, it should be the same color as the product (e.g., a stack of sanitary paper) (white for normal products, a mark of the same color for colored products).

[0041] Because the packaging roll 1 is made up of a plurality of individual packaging sheets 2 with different designs alternately connected, the individual packaging machine 40 sequentially packages the individual sheet bundles 3 using the individual packaging sheets 2 cut from the packaging roll 1 in order. Therefore, as shown in FIG. 5 , individual packages 4 with different designs covered by individual packaging sheets 2 with different designs are sequentially discharged from the individual packaging machine 40. In the example shown in FIG. 5 , the individual packaging machine 40 is supplied with a packaging roll 1 in a pattern in which two types of individual packaging sheets 2 are arranged alternately, and therefore individual packages 4 with two different designs are alternately discharged from the individual packaging machine 40 in accordance with the pattern of the packaging roll 1. In this way, the order of the individual packages 4 discharged from the individual packaging machine 40 corresponds to the pattern of the individual packaging sheets 2 that make up the packaging roll 1 supplied to the individual packaging machine 40.

[0042] The individual packaging machine 40 cuts the packaging roll 1 between the individual packaging sheets 2 to obtain individual packaging sheets 2, and then individually packages each of the individual sheet bundles 3 carried in by the carry-in device 30 with the individual packaging sheets 2. The individual packaging machine 40 sequentially packages the individual sheet bundles 3 using the individual packaging sheets 2 obtained as described above. A known individual packaging machine such as that disclosed in Patent Document 3 can be used as the individual packaging machine 40. Specifically, the individual packaging machine 40 may be configured to spread the opening of the individual packaging sheet 2, and then, while maintaining the spread state of the individual packaging sheet 2, push the individual sheet bundle 3 into the individual packaging sheet 2 through the opening, and then join the individual packaging sheet 2 by heat sealing or the like. This results in an individually packaged item 4 in which the individual sheet bundle 3 (a stack of sanitary paper) is individually packaged with the individual packaging sheet 2.

[0043] Specifically, FIGS. 6 and 7 show an example of a process for individually packaging an individual sheet bundle 3. First, as shown in FIG. 6(a), an individual packaging sheet 2 is placed in the opening of a bucket 41 provided in the individual packaging machine 40. The individual sheet bundle 3 can be pushed into this bucket 41 together with the individual packaging sheet 2. The individual sheet bundle 3 is placed in front of the opening of the bucket 41 in an orientation such that the second side S2, i.e., the side on which the creases of the second sheet W2 folded downward by the outer guide 11b of the interfolder 11 are aligned, first contacts the individual packaging sheet 2 and is introduced into the bucket 41. Thereafter, as shown in FIG. 6(b), the individual sheet bundle 3 is pushed by a pusher 42 provided in the individual packaging machine 40 and pushed into the bucket 41 together with the individual packaging sheet 2. Specifically, the pusher 42 abuts the first side S1, i.e., the side on which the creases of the first sheet W1 folded upward by the inner guide 11a of the interfolder 11 are aligned. The individual sheet bundle 3 is then pushed from the first side surface S1 by the pusher 42, which repeatedly performs linear reciprocating motion, and is introduced into the bucket 41 while sliding on a flat surface (not shown). As described above, the first side surface S1 of the individual sheet bundle 3 has a surface with relatively even folds, making it suitable for being pushed by the pusher 42. As shown in FIGS. 6 and 7, it is preferable that the side edge of the topmost first continuous sheet W1 of the individual sheet bundle 3 be folded back once or more times to fold it in half, as in the example of FIG. 4. Because the thickness of the central portion of the individual sheet bundle 3 is thinner than the end portions, folding back the side edge of the topmost first continuous sheet W1 to position it in the center reduces the load on the short portion of the sheet during compression, and prevents the topmost first continuous sheet W1 from turning over during packaging. In addition, since the bottom fold relative to the seal is on the conveying surface opposite to the top sheet, the leading edge cannot be folded back, so the sheet ends near the end of the stack and are prone to curling up during packaging. Therefore, by arranging the sheet edge facing the seal, it is possible to prevent the bottom sheet from curling up during packaging and getting caught in the seal.

[0044] The coefficient of friction (JIS K7125:1999) of the sheet forming the individual packaging sheet 2 is preferably greater on the inside than on the outside (coefficient of friction: outside < inside). If the friction on the outside is high, the resistance between the sheet and the bucket 41 is greater during the wrapping process when the individual sheet stack 3 is compressed vertically and then inserted into the bucket 41 together with the sheet, making the individual sheet stack 3 more likely to buckle. In particular, in the case of a multi-machine, the cutting is performed at high speed, with the stack being pinched and pressed down from the top and bottom during cutting. This leaves the individual sheet stack 3 in a compressed state after cutting. To wrap the compressed individual sheet stack 3 in the sheet, it must be further compressed and wrapped. This increases the vertical pressure, making it more likely to buckle. Therefore, by making the coefficient of friction of the sheet forming the individual packaging sheet 2 greater on the inside than on the outside, the contact surface between the bucket 41 and the sheet is more slippery than the contact surface between the sheet and the individual sheet stack 3, making it easier to wrap the individual sheet stack 3 and resulting in a tightly packed product. There are several ways to make the friction coefficient of a sheet different between the front and back, such as forming multiple layers or applying a surface treatment, but it is also possible to increase the resistance value of the ink-coated area by printing a design on the inside of the sheet.

[0045] FIG. 7(a) shows the state in which the top, bottom, and second side surface S2 of the individual sheet bundle 3 are covered by the individual packaging sheet 2 after the above steps. In this state, the first side surface S1 of the individual sheet bundle 3 is not yet covered by the individual packaging sheet 2. In this state, there is still an excess portion of the individual packaging sheet 2 on the first side surface S1 side of the individual sheet bundle 3. Next, as shown in FIG. 7(b), the excess portion of the individual packaging sheet 2 on the first side surface S1 side is folded back to further cover the first side surface S1 of the individual sheet bundle 3. At this time, the excess portion of the individual packaging sheet 2 is partially overlapped, and the sheets forming the individual packaging sheet 2 are partially doubled. Then, as shown in FIG. 7(b), a sealer 43 provided in the individual packaging machine 40 is pressed against the overlapping portion of the individual packaging sheet 2 to seal the overlapping portion. At this time, the overlapping portion of the individual packaging sheet 2 is sandwiched between the sealer 43 and the first side surface S1 of the individual sheet bundle 3. As described above, the first side surface S1 of the individual sheet bundle 3 has relatively uniform folds, making it suitable for pressing the sealer 43 against it to bond the overlapping portions of the individual packaging sheets 2. In other words, sandwiching and bonding the overlapping portions of the individual packaging sheets 2 between the sealer 43 and the first side surface S1 of the individual sheet bundle 3 can prevent uneven sealing at the overlapping portions. The sealer 43 may be a heat sealer that applies heat to the individual packaging sheet 2 to melt the sheet, or an ultrasonic sealer that applies ultrasonic vibrations to the individual packaging sheet 2 to generate frictional heat to melt the sheet. In this way, the individual sheet bundle 3 is wrapped around the body by the individual packaging sheet 2. In other words, the top, bottom, first side surface S1, and second side surface S2 of the individual sheet bundle 3 are covered by the individual packaging sheet 2.

[0046] FIG. 8 shows an example of an individual sheet bundle 3 wrapped around a body by an individual packaging sheet 2 after the above process. The direction parallel to the folds of each sheet in the individual sheet bundle 3 is referred to as the "width direction," the direction perpendicular to the width direction of the individual sheet bundle 3 in a plan view (i.e., the direction in which the individual sheet bundle 3 is cut) is referred to as the "depth direction," and the direction in which the sheets of the individual sheet bundle 3 are stacked is referred to as the "thickness direction." Also, in FIG. 8, the "MD direction" of the individual packaging sheet 2 refers to the flow direction (extrusion direction) during sheet production, and the "CD direction" of the individual packaging sheet 2 refers to the direction perpendicular to this flow direction. Because the MD direction of a sheet is parallel to the molecular orientation of the sheet, a typical sheet has the property of being easily torn in the MD direction. On the other hand, because the CD direction of a sheet is perpendicular to the molecular orientation of the sheet, a typical sheet has the property of being difficult to tear in the CD direction.

[0047] In the example shown in FIG. 8 , the width direction of the individual sheet bundle 3 coincides with the MD direction of the individual packaging sheet 2, and the depth direction of the individual sheet bundle 3 coincides with the CD direction of the individual packaging sheet 2. Therefore, in this example, the tear strength of the individual packaging sheet 2 (JIS K7128-2:1998 Testing method for tear strength of plastic films and sheets) is preferably greater in the depth direction of the individual sheet bundle 3 (CD direction of the individual packaging sheet 2) than in the width direction of the individual sheet bundle 3 (MD direction of the individual packaging sheet 2). In other words, it is preferable that the individual packaging sheet 2 be easily torn along the width direction of the individual sheet bundle 3. In particular, the tear strength in the depth direction is preferably at least three times, and more preferably at least five times, the tear strength in the width direction (tear strength: width direction × 5 ≦ depth direction). Therefore, as shown in FIG. 8( a), forming an opening perforation 2b in the individual packaging sheet 2 along the width direction of the individual sheet bundle 3 has the advantage of making the perforation 2b easier to open.

[0048] Furthermore, the individual packaging sheet 2 is more likely to stretch in the depth direction (CD direction) of the individual sheet bundle 3 than in the width direction (MD direction) of the individual sheet bundle 3. The tensile elongation (tensile strain) (JIS K7127) indicates the degree to which a sheet can stretch, and is the elongation percentage (%) at which a sheet reaches the first yield point or breaks without reaching the yield point at a speed of 300 mm / min. Therefore, as described with reference to Figure 6, when the individual sheet bundle 3 is wrapped in the individual packaging sheet 2, the individual sheet bundle 3 easily fits to the individual packaging sheet 2 during individual packaging, which is advantageous.

[0049] When considering the formation of the perforations 2b, the width direction of the individual sheet bundle 3 and the MD direction of the individual packaging sheet 2 are aligned as shown in Figure 8(a), and the proportion of the cut portion of the perforations 2b is preferably 55% or less, and more preferably 40% or less. The length of each cut portion is preferably 1 to 3 mm. The length of the non-cut portion is preferably 1 to 8 mm.

[0050] In this way, an individual sheet bundle 3 is individually packaged with an individual packaging sheet 2 to obtain an individually packaged item 4. As shown in the example of Fig. 8, the individual package 4 may be formed by covering both end faces of the individual sheet bundle 3 with the individual packaging sheet 2 and joining the covered portions of the end faces by heat sealing or the like to form side seal portions 2c. In this way, by forming the side seal portions 2c in the individual packaging sheet 2, almost the entire individual sheet bundle 3 can be covered.

[0051] Furthermore, the side seal portion 2c of the individual packaging sheet 2 is preferably not heat-sealed across the entire surface but is heat-sealed intermittently (e.g., in stripes). In this case, the seal width is preferably 1.5 to 5.0 mm, and the non-seal width is preferably 1.6 to 10.0 mm, with the seal width being smaller than the non-seal width (seal width < non-seal width). This is because if the total area of ​​the seal width exceeds 50% of the side seal surface, the corners of the individual package will become hard and there is a risk of damaging the packaging film 5 when inserted into the packaging film 5. In particular, the seal width is preferably narrower, since the continuous seal width at the corners will be smaller; for example, 3.5 mm or less is preferred, and 2.5 mm or less is more preferred. However, a seal width of less than 1.5 mm is not preferred because it is too narrow, making it difficult for heat to transfer and resulting in an unstable seal.

[0052] On the other hand, it is also possible to not form the side seal portion 2c on the individual packaging sheet 2. That is, the individual sheet bundle 3 may be wrapped around the body with the individual packaging sheet 2, leaving both or one of the end faces (the cut surfaces created when cutting) of the individual sheet bundle 3 open. The individual package 4, in which the individual sheet bundle 3 is simply wrapped around the body, is easily usable, for example, for refilling the individual sheet bundle 3 into another storage case. In this case, it is useful for refilling the contents of a case, etc., and is easy to open and requires little material, so no unnecessary materials are needed. Furthermore, a configuration in which the side seal portion 2c is not formed on the individual packaging sheet 2 is preferable because there are no side faces formed by folding the individual packaging sheet 2, and the corners of the individual package 4 are less likely to become hard. This is particularly suitable when using paper, glassine paper, or composite sheets containing these for the individual packaging sheet 2.

[0053] 6, it is preferable to further perform a step of compressing the individual sheet bundle 3 in the thickness direction before covering the individual sheet bundle 3 with the individual packaging sheet 2. Specifically, the compression step is a step of pressing the individual sheet bundle 3 in the thickness direction to bring the layers of the individual sheet bundle 3 into closer contact with each other and reduce the thickness of the individual sheet bundle 3. It is preferable that the individual sheet bundle 3 is covered with the individual packaging sheet 2 in a state compressed in the thickness direction. The compression rate of the individual package 4 (also referred to as the "individual package compression rate") is preferably 97% or more, and more preferably 98% or 99% or more. Specifically, the compression rate of the individual package 4 may be 98 to 105%, and preferably 98 to 103%.

[0054] The individual packaging compression rate is calculated using the following formula. [Formula] Individual packaging compression rate = Individual packaging circumference ÷ Theoretical circumference calculated from the outer dimensions of the product bundle Here, the theoretical circumference calculated from the external dimensions of the product bundle is calculated as (thickness (set) x 2 x number of sets + bundle depth) x 2. Note that thickness is the thickness of a set (2 sheets) under a load of 2 kPa (ISO 12625-3:2014). The circumference of the individual package is calculated as (product height + product depth) x 2. The bundle depth is the average of the maximum depth dimensions measured at three points, the end and the center, when viewed from above of the individual sheet bundle 3, measured on 10 individual sheet bundles 3.

[0055] Returning to FIG. 5 , in the conveying process, the individual packages 4 are conveyed by a conveying device 50 using a known conveyor or the like. Specifically, this conveying process is a process of conveying a plurality of individual packages 4 downstream in the section between the individual packaging process described above and the collective packaging process described below. As described above, the individual packages 4 of a plurality of different designs are arranged at intervals in a predetermined pattern on the conveying device 50. During this conveying process, a sensor (not shown) may be used to inspect whether the arrangement order of the individual packages 4 on the conveying device 50 is correct. The sensor may be any known sensor capable of identifying the design of the individual packages 4 (individual packaging sheets 2), such as an image sensor such as a CMOS or CCD, or a color sensor that simply detects color. For example, an image sensor may be used when the design of the individual packages 4 (individual packaging sheets 2) is complex, while a color sensor may be used when the difference in the design of the individual packages 4 is simply a color difference. The information detected by the sensor is transmitted to a control device (not shown) such as a computer, and analysis and processing are performed by the control device. If the control device determines as a result of the analysis process that the arrangement of the individual packages 4 is improper, it can drive a known exclusion device (not shown) to remove the improper individual packages 4 from the conveying device 50. This makes it possible to correct the arrangement of the individual packages 4 on the conveying device 50 to the proper one.

[0056] In the collective packaging process, the individual packages 4 that have undergone the above-described conveying process are introduced into a collective packaging machine 60. The collective packaging machine 60 collectively packages (packs) multiple individual packages 4 in a single exterior film 5 to obtain a collective package 6 (packaged product). The exterior film 5 is preferably a transparent or translucent resin film so that the design of the individual packages 4 can be seen from the outside. The collective packaging machine 60 mechanically arranges the individual packages 4 in the order they are introduced into the collective packaging machine 60 and then collectively packages the multiple individual packages 4 in the exterior film 5. The collective packaging machine 60 does not generally change the arrangement order of the individual packages 4. Therefore, it is preferable to properly arrange the individual packages 4 before introducing them into the collective packaging machine 60. The collective packaging machine 60 can change the orientation of the individual packages 4 before collective packaging. Such collective packaging machines 60 are well known, and the one disclosed in Patent Document 4, for example, may be used. Furthermore, the number of individually packaged items 4 packaged in one exterior film 5 is 4 to 12, but is not limited to this and can be any number.

[0057] FIG. 9 shows an example of an exterior film 5 used in the collective packaging process. As shown in FIG. 9, the exterior film 5 may have gusset portions 6a on both sides. The gusset portions 6a are formed by folding the sides of the exterior film 5 inward, forming peaks with peaks on the inner side of the exterior film 5. The fold lines forming the gusset portions 6a extend along the vertical direction of the exterior film 5. The exterior film 5 having the gusset portions 6a can be made into a bag shape by folding a single flat film and forming sealed portions 6b at the overlapping portions by heat sealing or the like. In this case, it is preferable that the sealed portions 6b of the exterior film 5 are not formed at the corners (indicated by dotted circles) that form the folds of the gusset portions 6a. In particular, it is preferable that the sealed portions 6b of the exterior film 5 are formed in the areas that form the surfaces that are folded when the gusset portions 6a are formed, as shown in FIG. 9. Because the sealed portion 6b is more easily torn than other portions, if the sealed portion 6b is formed at a corner of the exterior film 5, when multiple individual packages 4 are placed inside the exterior film 5, the corners of the individual packages 4 may come into contact with the corners, potentially damaging the individual packages 4 and causing them to tear. On the other hand, as shown in FIG. 9 , by forming the sealed portion 6b at a folded portion of the gusset portion 6a, the sealed portion 6b is less likely to come into contact with the individual packages 4, making it less likely to damage the exterior film 5 even in tightly packed aggregate packaging. Furthermore, it is preferable to insert multiple individual packages 4 downward from the top opening shown in FIG. 9 into the exterior film 5. When inserting the individual packages 4 downward from the top opening of the exterior film 5 in this way, the corners of the individual packages 4 (portions hardened by the seal) are more likely to come into contact during insertion, so it is preferable to use a soft film material for the individual packages 4. Furthermore, it is preferable not to compress the individual packages 4 when placing them in the exterior film 5.

[0058] In addition to the exterior film 5 having the gusset portion 6a as described above, it is also possible to use a film material without a circumferentially sealed portion, such as a film material formed by inflation. Inflation is a method of forming a film material into a three-dimensional shape by inflating it with a gas such as air. When an inflation-formed film is used for the exterior film 5, a sealed portion such as the gusset portion 6a is not necessary. Furthermore, inflation-formed film has improved tear strength in the MD because the film itself is stretched in the CD as well during the manufacturing process.

[0059] The tear strength of the exterior film 5 in the MD direction of the film is preferably 0.3 N or more. In particular, the tear strength of the exterior film 5 in the MD direction is more preferably 0.5 N or 0.6 N or more, and particularly preferably 0.8 N or 1.0 N or more. The tear strength of the exterior film 5 can also be 1.5 N or 1.8 N or more. On the other hand, from the viewpoint of reducing costs, the tear strength of the exterior film 5 is preferably 3.5 N or less, more preferably 3.0 N or less, and particularly preferably 2.5 N or less. The tear strength of the exterior film 5, like the tear strength of the individually wrapped sheet 2, is measured in accordance with JIS P 8116:2022 (Paper - Tear strength test method - Elmendorf tear tester method).

[0060] Furthermore, when inserting the individual packages 4 into the exterior film 5, it is preferable that the MD direction of the exterior film 5 and the insertion direction of the individual packages coincide. That is, in the example shown in Fig. 9, the individual packages 4 are inserted into the exterior film 5 from top to bottom in the drawing, and in this state, it is preferable that the MD direction of the exterior film 5 coincides with the up-down direction in the drawing.

[0061] The exterior film 5 has a basis weight of 22 to 42 g / m 2 It is preferable that the density is 26 to 35 g / m 2It is more preferable that the basis weight of the packaging film 5 is 22 g or more. When the basis weight of the packaging film 5 is 22 g or more, tearing of the packaging film 5 can be further suppressed. On the other hand, if the basis weight of the packaging film 5 exceeds 42 g, it is not preferable from the viewpoint of increasing costs. The basis weight of the packaging film 5 is measured in accordance with JIS P 8124:2011 (Paper and paperboard -- Method of measurement of basis weight).

[0062] Furthermore, the exterior insertion rate when inserting the multiple individual packages 4 covered by the exterior film 5 may be 96 to 110%. In particular, this exterior insertion rate is preferably 98 to 106%, and more preferably 99 to 103%. In other words, it is preferable that the multiple individual packages 4 are stored within the exterior film 5 with a certain amount of space between them. The exterior insertion rate of the individual packages 4 is the inner periphery of the exterior film 5 in the depth direction relative to the theoretical periphery in the depth direction of the multiple individual packages 4 when inserted (100%) (exterior film periphery ÷ theoretical periphery). The theoretical periphery in the depth direction of the multiple individual packages 4 can be calculated by (theoretical periphery in the depth direction of the multiple individual packages) = (longitudinal width of the individual packages) × 2 × number of longitudinal rows + (depth width of the individual packages) × 2 × number of depth rows. [Example]

[0063] Next, examples and comparative examples of the present invention will be described with reference to the following Table 1. In the examples and comparative examples, individual sheet bundles 3, which are sanitary paper bundles, were individually packaged with individual packaging sheets 2, which were resin films, to obtain individually packaged items 4. Thereafter, a plurality of the individually packaged items 4 were bundled together and collectively packaged with a gusset-type (see FIG. 9) resin film outer film 5 to obtain a collective package 6.

[0064] [Table 1]

[0065] Table 1 shows the configurations and physical properties of Examples 1 to 15 and Comparative Examples 1 and 2. In Table 1, "Number of rows width" and "Number of rows depth" refer to the number of rows in which the individual packages 4 are arranged in the width and depth directions, respectively, of the collective package 6 as shown in FIG. 8. In other words, "Number of rows width: 1" and "Number of rows depth: 1" mean that the individual packages 4 are not arranged in a flat plane but are stacked in the thickness direction. In Examples 1 to 15 and Comparative Examples 1 and 2, the number of individual packages 4 stacked in the thickness direction is five. "Periphery length [mm]" refers to the periphery of the outer bag (width × 2 + gusset width × 4). "Theoretical circumference [mm]" refers to the theoretical circumference in the depth direction of the individual packages 4, and as described above, is calculated by (theoretical circumference in the depth direction of multiple individual packages) = (longitudinal width of individual packages) × 2 × number of longitudinal rows + (depth width of individual packages) × 2 × number of depth rows. The "outer packaging insertion rate" is the rate at which the individual packages 4 are inserted into the outer packaging film 5, and as mentioned above, is calculated as the inner circumference of the outer packaging film 5 in the depth direction relative to the theoretical outer circumference (100%) of the multiple individual packages 4 in the depth direction at the time of insertion (outer packaging pack circumference ÷ theoretical outer circumference).

[0066] "Individual package width [mm]", "individual package depth [mm]", and "individual package height [mm]" are the lengths of the individually packaged item 4 in the width direction, depth direction, and thickness direction (see Figure 8), respectively.

[0067] The "contents width [mm]" and "contents depth [mm]" of the individual sheet bundle (contents) are the lengths of the individual sheet bundle 3 in the width direction and depth direction (see Figure 8), respectively. The "contents theoretical height [mm]" is the theoretical height of the individual sheet bundle 3 in the thickness direction (see Figure 8), and is calculated as follows: thickness (set) x number of sets x 2. The "thickness (set) [μm]" is the thickness of one set that makes up the individual sheet bundle 3. The "number of sets" is the number of sets of sheets that make up the individual sheet bundle 3.

[0068] "Individual packaging sheet perimeter [mm]" is the inner perimeter of the individual packaging sheet 2 in the depth direction. "Bundle theoretical perimeter [mm]" is the outer perimeter of the individual sheet bundle 3 in the depth direction. As mentioned above, the "individual packaging compression rate" can be calculated from the theoretical perimeter calculated by dividing the outer dimensions of the product bundle by the individual packaging compression rate = individual packaging perimeter.

[0069] "Individual packaging material" refers to the type of resin film that forms the individual packaging sheet 2, and PE refers to polyethylene. "Individual packaging basis weight [g / m 2 ]' is the basis weight of the individual packaging sheet 2. 'Stiffness T [mN·m]' is the bending stiffness in the MD direction of the individual packaging sheet 2, 'Stiffness Y [mN·m]' is the bending stiffness in the CD direction of the individual packaging sheet 2, and 'Stiffness √TY [mN·m]' is the geometric mean of stiffness T and stiffness Y. Bending stiffness was determined using a method in accordance with "Method for measuring deflection due to dead weight TAPPI UM409" described in the "Paper and Pulp Testing Methods" (Paper and Pulp Technology Association).

[0070] More specifically, the bending stiffness of a film is expressed by the following formula: [Formula] Bending stiffness (mN·m) = (wL4 / 8y) × 9.81 Here, w is the basis weight (g / m2), L is the bending length (m), and y is the degree of deflection (m). The degree of deflection y is measured as follows: [Measurement method] A sample piece of film 30 mm wide and 150 mm long was prepared, and this sample piece was placed on a right-angled stand with the tip of the film sticking out 30 mm (bending length L). The sample piece was held down on the stand so that it did not float, and the vertical length of the hanging tip (degree of deflection y) was measured. Measurements were taken at n=10 points on each side of the film, for a total of 20 points, and the average was calculated.

[0071] "Exterior material" refers to the type of resin film that forms the exterior film 5, and PE refers to polyethylene. "Exterior basis weight [g / m 2]' is the basis weight of the resin film forming the exterior film 5. "Tear strength [N]" is the tear strength of the exterior film 5 in the MD direction. "Tear" was evaluated by visually checking whether or not tears had occurred in the exterior film 5 after multiple individually packaged items 4 had been stored, and the evaluation was based on "×", "△", "○", or "◎". "×" indicates tears, "△" indicates no tears but some clear marks, "○" indicates no tears but some faint marks, and "◎" indicates no tears or marks, with "△", "○", and "◎" being evaluated as passing. "Tightness" refers to the amount of excess exterior film 5 after multiple individually packaged items 4 have been stored (the amount of excess exterior film 5). The excess amount was determined by pinching the excess portion and measuring the length with a metal ruler, then doubling the length, and the excess amount was evaluated as "×", "△", "○", or "◎". "×" indicates that the excess amount exceeds 35mm, "△" indicates that the excess amount is 35mm or less but over 28mm, "○" indicates that the excess amount is 28mm or less but over 20mm, and "◎" indicates that the excess amount is 20mm or less.

[0072] As shown in Table 1, in Comparative Example 1, the tear strength of the exterior film 5 was 0.2 N, indicating that a relatively low-strength film was used. As a result, Comparative Example 1 received a tear rating of ×, indicating that tearing occurred in the exterior film 5 when multiple individually packaged items 4 were stored in the exterior film 5. In Comparative Example 2, the tear strength of the exterior film 5 was 1.3 N, indicating that a relatively high-strength film was used, but the stiffness √TY of the individual packaging sheet 2 was 0.0061 mN·m, indicating that a relatively hard film was used. As a result, Comparative Example 2 also received a tear rating of ×, indicating that tearing occurred in the exterior film 5 when multiple individually packaged items 4 were stored in the exterior film 5. These Comparative Examples 1 and 2 revealed that even when a film with a relatively high tear strength is used as the exterior film 5, if a film with a relatively high stiffness √TY value is used as the individual packaging sheet 2, there is a possibility that tearing may occur in the exterior film 5 during the production process of the collective package 6.

[0073] On the other hand, as shown in Table 1, in Examples 1 to 15, the tear strength of the packaging film 5 was in the range of 0.5 to 2.0 N, and the stiffness √TY value of the individual packaging sheet 2 was in the range of 0.0022 to 0.0057 mN·m. In all of Examples 1 to 15, no tearing of the packaging film 5 was observed.

[0074] In particular, Examples 1 to 6 received the highest rating (◎) for both tearing and tightness, with no tearing observed during the manufacturing process and almost no looseness observed in the exterior film 5 even after a plurality of individually packaged items 4 were placed in the exterior film 5. In Examples 1 to 6, the tear strength of the exterior film 5 was in the range of 1.3 to 2.0 N, and the stiffness √TY value of the individual packaging sheet 2 was in the range of 0.0022 to 0.0044 mN·m. Therefore, it can be said that it is preferable for the tear strength of the exterior film 5 and the stiffness √TY value of the individual packaging sheet 2 to be within the ranges of Examples 1 to 6 above.

[0075] In the above description of the present invention, the embodiments of the present invention have been described with reference to the drawings in order to express the contents of the present invention. However, the present invention is not limited to the above embodiments, and includes modifications and improvements that are obvious to those skilled in the art based on the matters described in the present specification. [Explanation of symbols]

[0076] 1...Packaging roll 2...Individual wrapping sheet 2a...Sealed part 2b...Perforation 2c...Side seal part 3...Individual sheet bundle 3´…continuous sheet bundle 4…individually packaged item 5...Outer film 6...Assembled packaging 6a...gusset part 6b...seal part 10...Folding mechanism 11...Interfolder 11a...Inner guide 11b...Outer guide 12...Conveyor 20...Cutting device 21...Cutter 22...Conveyor 30...Loading device 31...Lower conveyor 32...Upper conveyor 40...Individual packaging machine 41...Bucket 42...Pusher 43...Sealer 50...Conveyor device 60…Collection packaging machine 70…Unloading device W...Sheet W1...First sheet W2: Second sheet W´: Continuous sheet W'1: First continuous sheet W'2: Second continuous sheet S1...First side S2...Second side

Claims

1. A packaged product including an individual package obtained by packaging a sheet bundle in which a plurality of sheets are stacked with an individual packaging sheet, and an exterior film in which a plurality of the individual packages are packaged together, The individual wrapping sheet has a value of √TY, which is the geometric mean of the bending stiffness T in the MD direction and the bending stiffness Y in the CD direction, of 0.0014 to 0.0060 mN m; The exterior film has a tear strength in the MD direction of 0.3 N or more. packaging products.

2. The √TY value of the individual wrapping sheet is 0.0050 mN·m or less. The packaging product of claim 1.

3. the bending stiffness T of the individual wrapping sheet is 0.0018 to 0.0060 mN m; The bending stiffness Y of the individual wrapping sheet is 0.0020 to 0.0065 mN m, The packaging product of claim 1.

4. The tear strength of the exterior film in the MD direction is 1 N or more. The packaging product of claim 1.

5. the packaging insertion rate of the individual packages relative to the packaging film is 98 to 106%, Here, the outer packaging insertion ratio is the inner circumference of the outer packaging film relative to the theoretical outer circumference (100%) of the multiple individual packages when inserted. The packaging product of claim 1.

6. The compressibility of the individual package is 98 to 105%. The packaging product of claim 1.

7. The coefficient of friction of the inner surface of the individual wrapping sheet is greater than the coefficient of friction of the outer surface of the sheet. The packaging product of claim 1.

8. a folding step of folding a plurality of continuous sheets to obtain a continuous sheet bundle in which first continuous sheets folded upward and second continuous sheets folded downward are alternately stacked; a cutting step of individually cutting the continuous sheet bundle to obtain a plurality of individual sheet bundles; an individual packaging step of individually packaging the individual sheet bundles with individual packaging sheets; a collective packaging step of packaging a plurality of the individual packages together in a single outer packaging film to obtain a packaged product, The individual wrapping sheet has a value of √TY, which is the geometric mean of the bending stiffness T in the MD direction and the bending stiffness Y in the CD direction, of 0.0014 to 0.0060 mN m; The exterior film has a tear strength in the MD direction of 0.3 N or more. Manufacturing methods for packaging products.

Images