Packaging bags

Abstract

To provide a packaging bag with a sleeve that has excellent water and oil resistance, sufficient rigidity and a dead-hold property without requiring excessive thickness, and that is excellent in appearance, and can be easily removed from a bag body after use.SOLUTION: The bag includes: a bag body; a sleeve for imparting the bag body a square cylindrical three-dimensional shape and making it self-standing and stackable; and an adhesive portion for bonding the sleeve to an inner surface of the bag body. The bag body is formed of a front portion, a back portion, and side face portions that face the front portion and the back portion. The sleeve contains polyolefin and 20 to 75 mass% of a filler. There are formed, on a surface of the sleeve, four first creases to assist in folding the sleeve into a square cylindrical shape and two second creases to assist in folding the sleeve into a flattened shape, each formed in a straight line to extend along the height direction of when the packaging bag is self-standing.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a packaging bag. This application claims priority to Japanese application No. 2018-038827, filed on March 5, 2018, the contents of which are incorporated herein by reference. [Background technology]

[0002] A known packaging bag for containing tea bags and the like has a three-dimensional shape formed by providing a rectangular cylindrical sleeve on the inside of a bag body made of a film material. Before use, the sleeve of this packaging bag is adhered to the inside of the bag body in a flat state. When used, the sleeve is folded into a cylindrical shape, and the excess part of the bag body is folded to fit the shape of the sleeve. This gives the packaging bag a three-dimensional box-like shape, and allows it to stand on its own and be stacked.

[0003] As the sleeve, a foldable sleeve made of paper or synthetic resin has been proposed (see, for example, Patent Document 1). Also, a plastic sleeve using a polyethylene film as the synthetic resin has been proposed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-322187 [Patent Document 2] Japanese Patent Publication No. 2004-175408 Summary of the Invention [Problem to be solved by the invention]

[0005] A sleeved packaging bag using a paper sleeve has a problem that wrinkles occur in the film material depending on the storage conditions, resulting in a poor appearance. This problem is related to the property of the paper sleeve, which expands when it absorbs moisture and shrinks when it dries. In the case of a sleeved packaging bag using a paper sleeve, the difference between the amount of dimensional change due to the fluctuation in the moisture content of the paper sleeve caused by seasonal differences and the amount of dimensional change of the film material is a problem. Therefore, in order to reduce wrinkles in the packaging bag, it is necessary to control the humidity of the paper sleeve and the packaging bag during storage. In the case of a sleeved packaging bag using a paper sleeve, wrinkles may also occur depending on the moisture content of the contents to be packaged. In particular, there is a problem that the flat part, which is a characteristic of the packaging bag given a three-dimensional rectangular parallelepiped shape by the sleeve, is easily noticeable when wrinkles occur, resulting in a poor appearance. Furthermore, the flat part is often the front design of the packaging bag, which may impair the value of the product when it is displayed. In addition, because paper sleeves have lower water and oil resistance than plastic sleeves, the moisture and oil contained in the contents may be absorbed by the paper sleeve, causing the contents to deteriorate. If the moisture and oil contained in the contents are absorbed and the paper sleeve partially discolors, this discoloration can be seen through the film material, which may result in a poor appearance and a decrease in commercial value. For these reasons, the uses of paper sleeves as packaging bags are limited. Furthermore, when paper sleeves are disposed of, paper fibers tend to remain on the bag itself, which can cause problems when separating the bags for disposal.

[0006] Plastic sleeves do not cause problems with wrinkles during use, have excellent water and oil resistance, and are made of the same material as film materials, so there is no problem with separate disposal. However, plastic sleeves are inferior in rigidity and dead-hold properties to paper sleeves, so it is difficult to give a firm three-dimensional shape to the bag body and ensure self-supporting and stacking properties with the same thickness as paper sleeves. Therefore, plastic sleeves need to be thicker than paper sleeves. However, if an attempt is made to ensure sufficient rigidity with plastic sleeves by increasing the thickness, the dead-hold properties deteriorate and the three-dimensional shape of a square tube becomes closer to a round tube, making it difficult to stack adjacent packaging bags in a close contact manner, resulting in poor stacking properties. Furthermore, when the plastic sleeve is heat sealed to the inner surface of the bag body, which uses the same type of resin as the plastic sleeve on the inner surface of the film material, the film material and the plastic sleeve are strongly bonded together, which can make them difficult to peel apart when they are required to be disposed of separately, and can cause problems with separating the materials for disposal.

[0007] To provide a sleeve which is excellent in water resistance and oil resistance, can secure sufficient rigidity and dead hold performance without being excessively thick, has an excellent appearance, and can be easily peeled off from a bag body after use, and a packaging bag using the sleeve. [Means for solving the problem]

[0008] The present invention has the following configuration. The sleeve according to the first aspect of the present invention is provided within a bag body in a tubular state so as to contact the inner surface of the bag body, imparting a three-dimensional shape to the bag body, and contains a polyolefin and a filler. According to the sleeve according to the second aspect of the present invention, the content of the filler may be 20% by mass or more with respect to the total mass of the sleeve. According to the sleeve according to the third aspect of the present invention, a first fold line that assists in folding the sleeve into a rectangular tube shape may be formed on a surface of the sleeve. According to the sleeve of the fourth aspect of the present invention, the filler may be calcium carbonate or talc. A packaging bag according to a fifth aspect of the present invention comprises a bag body and the sleeve according to any one of the first to fourth aspects provided within the bag body. In the packaging bag according to the sixth aspect of the present invention, the sleeve may be tubular, giving the bag body a three-dimensional shape, and allowing the bag body to stand on its own and be stackable. In the packaging bag according to the seventh aspect of the present invention, an adhesive portion that adheres the sleeve to the inner surface of the bag body is provided in a portion other than the portion along a first fold line that assists in folding the sleeve into a rectangular tube, and the sleeve and the bag body may be adhered to each other by the adhesive portion. In the packaging bag according to the eighth aspect of the present invention, the adhesive portions may be provided along a second fold line that assists in folding the sleeve into a flat shape, at positions that sandwich the second fold line. Effect of the Invention

[0009] The sleeve of the present invention is used for packaging bags, has excellent water resistance and oil resistance, ensures sufficient rigidity and dead hold without being excessively thick, prevents deterioration of the appearance of the packaging bag, and can be easily peeled off from the bag body after use. The packaging bag of the present invention has sufficient self-supporting and stacking properties, has an excellent appearance, and the sleeve can be easily peeled off from the bag body after use. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view showing an example of a sleeve of the present invention in a cylindrical shape. [Diagram 2] 2 is a perspective view showing the sleeve of FIG. 1 in a flattened state. FIG. [Diagram 3] FIG. 2 is a front view showing an example of a packaging bag of the present invention in a flat state. [Figure 4] 4 is a perspective view showing a state in which the sleeve of the packaging bag in FIG. 3 is folded into a rectangular tube shape. [Diagram 5]5 is a perspective view showing the state in which the lower part of the packaging bag in FIG. 4 is flattened to form a bottom part. FIG. [Figure 6] 1 is a perspective view showing the appearance of a packaging bag with a bottom portion formed. FIG. [Figure 7] 7 is a perspective view showing a state in which the upper part of the packaging bag in FIG. 6 is folded toward the rear side. [Figure 8] FIG. 2 is a perspective view showing a packaging bag formed in a box shape. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [sleeve] The sleeve of the present invention is provided in a bag body in a cylindrical state so as to contact the inner surface of the bag body, thereby imparting a three-dimensional shape to the bag body, and contains polyolefin and a filler. By using the sleeve of the present invention, a three-dimensional shape can be imparted to a packaging bag, making it self-supporting and stackable.

[0012] An example of the sleeve of the present invention will now be described with reference to Figs. In addition, the dimensions of the figures illustrated in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope that does not change the gist of the present invention.

[0013] The sleeve 10 of this embodiment is made of a long rectangular plate-like sheet 10A, and the thickness of the sleeve 10 is thicker than the film material constituting the bag body. The sleeve 10 is formed into a cylindrical shape by bonding both ends 10a, 10b of the plate-like sheet 10A in the longitudinal direction to each other. The end 10a and the end 10b of the plate-like sheet 10A in the longitudinal direction are overlapped and bonded so that the end 10b is located inside the end 10a. The method for bonding one end 10a and the other end 10b of the plate-like sheet 10A is not particularly limited, and examples thereof include a method of welding by heat sealing, a method of bonding by an adhesive, and the like.

[0014] The form of the sleeve is not limited to a form in which both ends in the length direction of the plate-like sheet are bonded to each other. For example, it may be a form in which both ends in the length direction of the plate-like sheet are butted together and the ends are not bonded to each other. Even in the case of a sleeve in which the butted ends are not bonded to each other in this way, if the sleeve is bonded to the inner surface of the bag body, a three-dimensional shape can be imparted to the bag body. In this case, the bonding portions 14a and 14b to be bonded to the sleeve and the bag body are shown in FIG. 1. In this embodiment, the bonding portions 14a and 14b are provided along the fold line 12a at positions sandwiching the fold line 12a. Similarly, the bonding portions 14a and 14b are provided along the fold line 12b at positions sandwiching the fold line 12b. As described later, the bonding portions 14a and 14b become the bonding portions 14a and 14b after being bonded to the bag body.

[0015] Four fold lines (first fold lines) 11a-11d for assisting in folding the sleeve 10 into a rectangular tube are formed on the outer surface 10c of the sleeve 10. The four fold lines 11a-11d are formed at intervals in the length direction of the plate-like sheet 10A, i.e., in the circumferential direction of the sleeve 10. The four fold lines 11a-11d are also formed linearly so as to extend in the width direction of the plate-like sheet 10A, i.e., along the height direction of the sleeve 10 when the packaging bag stands on its own. The fold lines are creases for folding the sleeve into a cylindrical shape, and are also called creases.

[0016] In addition, two creases (second creases) 12a, 12b are formed on the surface 10c of the sleeve 10. The creases 12a, 12b assist in folding the sleeve 10 into a flat shape. The crease 12a is formed linearly between two adjacent creases 11a, 11b on the outer surface 10c of the sleeve 10 so as to extend along the width direction of the plate-like sheet 10A, i.e., the height direction of the sleeve 10. The crease 12b is formed linearly between two other adjacent creases 11c, 11d on the surface 10c of the sleeve 10 so as to extend along the width direction of the plate-like sheet 10A, i.e., the height direction of the sleeve 10. The creases 12a and 12b are formed at positions that face each other when the sleeve 10 is formed into a rectangular tube shape.

[0017] The sleeve 10 can be made into a rectangular tube shape by folding at right angles along each of the four fold lines 11a to 11d as shown in Fig. 1. The sleeve 10 can also be made into a flat shape by folding along the two fold lines 12a and 12b as shown in Fig. 2. In this way, the sleeve 10 is configured to be freely foldable. In the sleeve 10, in the portion where both ends 10a, 10b in the longitudinal direction of the plate-like sheet 10A are overlapped and bonded, the edge 10d of the end 10a located outside the end 10b is formed to follow the fold line 11a. Therefore, when the sleeve 10 is formed into a rectangular tube, the edge 10d of the end 10a overlapping the outside of the end 10b of the plate-like sheet 10A coincides with the corner of the rectangular tube. As a result, when the sleeve 10 is bonded to the inner surface of the bag body to form a rectangular tube, the step at the portion where the edge 10d of the end 10a overlapping the outside of the end 10b of the plate-like sheet 10A is located coincides with the corner of the bag body and is not noticeable, and the aesthetic appearance of the product is improved. In addition, in the sleeve of the present invention, the shape of the sleeve when it is made into a cylindrical shape is not limited to a rectangular tube, and it may be, for example, a polygonal tube other than a rectangular tube, such as a hexagonal tube, or it may be a cylindrical shape, etc.

[0018] Each crease is a concave stripe. The cross-sectional shape of each crease perpendicular to the longitudinal direction is not particularly limited, and examples thereof include a rectangular shape, a triangular shape, a semicircular shape, and the like. The method for forming the creases is not particularly limited, and examples thereof include a method of pressing the edge of a blade.

[0019] The sleeve 10 contains polyolefin and a filler. That is, the sleeve 10 is composed of a plate-like sheet 10A containing polyolefin and a filler.

[0020] The sleeve 10 is made of a plastic containing polyolefin, and is therefore more water-resistant and oil-resistant than a paper sleeve. This makes the sleeve 10 less likely to absorb moisture and oil contained in the contents, and prevents deterioration of the contents and discoloration, making it suitable for a wide range of applications. Furthermore, while the dimensions of a paper sleeve change when affected by humidity, the sleeve 10 of the present invention is not affected by humidity during storage and does not change in dimensions. Therefore, when the sleeve 10 is formed into a cylindrical shape within the bag body, the film material of the bag body located outside the sleeve 10 can be pulled and tensioned as designed, resulting in a packaging bag with a flat surface and excellent appearance. In addition, because the sleeve 10 is made of a lightweight plastic containing polyolefin, it consumes less energy and emits less greenhouse gases throughout the life cycle of the packaging bag, from when it is manufactured, to when it is used, and finally when it is disposed of, compared to a paper sleeve.

[0021] The polyolefin is not particularly limited, and examples thereof include polyethylene (PE) such as high density polyethylene (HDPE), medium density polyethylene (MDPE), high pressure low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and other polyethylene-based resins such as ethylene-vinyl acetate copolymer; polypropylene-based resins such as polypropylene (PP), ethylene-propylene copolymer, and α-olefin-propylene copolymer; cyclic polyolefin resins, and the like.

[0022] The polyolefin contained in the sleeve 10 is preferably the same type as the polyolefin contained in the heat-sealing layer of the bag body described below. The polyolefin contained in the sleeve 10 may be of only one type, or may be a mixture of two or more types depending on the application. As the polyolefin used for the sleeve 10, PP and PE are preferable from the viewpoint of ease of heat sealing to the bag body.

[0023] The sleeve 10 contains a filler, so that it has sufficient rigidity and excellent dead hold properties despite being made of plastic. In addition, the filler does not have heat sealability and acts as a heat seal inhibitor, so that the heat sealability of the sleeve 10 to the bag body is suppressed from becoming excessively high. Therefore, when the sleeve 10 is to be disposed of separately from the bag body after use of the packaging bag, the sleeve 10 can be easily peeled off from the bag body, and the peeled off trace is beautiful. Therefore, it can be used in both municipalities where the bag body and the plastic sleeve can be disposed of together, and municipalities where they cannot be disposed of together and require separation, so it is easy to comply with the different disposal regulations of each municipality.

[0024] The filler contained in the sleeve 10 is not particularly limited, and examples thereof include inorganic fillers such as talc, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, etc. Among these, talc and calcium carbonate are preferred. The filler contained in the sleeve 10 may be of one type or of two or more types.

[0025] In addition to the polyolefin and the filler, the sleeve 10 may contain other components in addition to the polyolefin and the filler. Examples of the other components include resins other than the polyolefin and various additives. Additives include, for example, pigments, slip agents, antioxidants, and the like. Examples of the pigment include titanium oxide, carbon black, etc. By adding a pigment to the sleeve, the sleeve can be colored in any color.

[0026] As the slip agent, slip agents commonly used in polyolefins for packaging can be used, such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, N-stearyl erucic acid amide, ethylene bis oleic acid amide, etc. Examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, etc. Each of them may be used alone, or two kinds may be used in combination.

[0027] The plate-like sheet 10A constituting the sleeve 10 has a single-layer structure and a multi-layer structure. In the case of a multi-layer structure, the layer of the sleeve 10 having at least a surface to be bonded to the film material is the plate-like sheet 10A containing polyolefin and a filler. Specific examples of the multi-layer structure include a two-layer structure of a polyolefin layer containing a filler and a polyolefin layer not containing a filler, and a three-layer structure having an intermediate layer. In the case of a three-layer structure, the intermediate layer is formed from a resin containing an oxygen absorbing substance, so that the function of preventing oxidation of the contents during the storage period after the contents are filled in the bag can be imparted. In addition, in the case of a three-layer structure, the intermediate layer is colored in a dark color such as black or gray, and the layers on both sides of the intermediate layer are colored white, so that the dark color tone of the intermediate layer blocks light and deterioration such as fading of the contents due to light can be suppressed.

[0028] The polyolefin content in the sleeve 10 is preferably 25% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less, based on the total mass of the sleeve 10. If the polyolefin content is equal to or more than the lower limit of the above range, the bag has excellent water resistance and oil resistance, has small dimensional change, and the film material of the bag body can be easily tensioned, making it easier to obtain a packaging bag with a good appearance. If the polyolefin content is equal to or less than the upper limit of the above range, the filler content can be relatively increased, making it easier to obtain various effects by adding a filler.

[0029] When the polyolefin contains PE and PP, the mass ratio of PE to PP is preferably from 0.05 to 19, and more preferably from 0.1 to 9. When the mass ratio is within this range, the dead hold property is good.

[0030] The content of the filler in the sleeve 10 is preferably 20% by mass or more, more preferably 20% by mass or more and 75% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, based on the total mass of the sleeve 10. If the content of the filler is equal to or more than the lower limit of the above range, a sleeve having superior rigidity and dead hold properties is easily obtained, and the sleeve can be more easily peeled off from the bag body. If the content of the filler is equal to or less than the upper limit of the above range, the content of the polyolefin can be relatively increased, and the effect of the polyolefin can be easily obtained.

[0031] The thickness of the sleeve 10 is preferably 150 μm or more and 1000 μm or less, and more preferably 200 μm or more and 500 μm or less. If the thickness of the sleeve 10 is equal to or more than the lower limit of the above range, sufficient rigidity and dead hold are easily obtained. If the thickness of the sleeve 10 is equal to or less than the upper limit of the above range, the packaging bag is less likely to become bulky, the number of packaging bags that can be accommodated in an outer container such as a cardboard box increases, and the outer container for packing a predetermined number of packaging bags can be made smaller, improving transportation efficiency.

[0032] There is no particular limitation on the method for producing the sleeve 10. Examples of methods for forming the plate-like sheet that constitutes the sleeve include a method of extrusion molding using a resin composition obtained by mixing a polyolefin and a filler with other components that are used as necessary. In the above explanation, the sleeve is made of a normal plate-like sheet, but a window may be formed in the flat surface of the sleeve as necessary. The window may be formed in a portion of the flat surface of the sleeve that corresponds to the front and back surfaces of the packaging bag, or in a portion that corresponds to the side surface. By forming a window in the flat surface of the sleeve, it becomes possible to visually check the contents from the outside through the window in the bag body. In an embodiment in which a window portion is formed in the flat surface of the sleeve, when printing is performed on the base material layer of the bag body, it is preferable to design the portion of the base material layer corresponding to the window portion so that the content can be seen, without printing, and when printing is performed on the portion corresponding to the window portion, it is preferable to consider the design so that the content can be seen. When providing a window, problems such as discoloration of the contents due to light may occur. In such cases, problems such as discoloration of the contents due to light can be prevented by adopting at least one of the following two methods. 1) A film that blocks ultraviolet rays is used as one of the layers constituting the laminate (the base layer or an intermediate layer that is laminated as necessary). 2) A coating layer for blocking ultraviolet rays is provided on the base material layer or on an intermediate layer to be laminated as required.

[0033] As described above, the sleeve of the present invention contains polyolefin and a filler, and therefore has improved water resistance and oil resistance compared to paper sleeves, and is less likely to absorb water or oil contained in the contents, making it suitable for use as a packaging bag for a wide range of applications. In addition, the dimensional change due to external factors such as moisture is smaller than that of a paper sleeve. Therefore, when the sleeve is formed into a cylindrical shape, the film material of the bag body can be pulled and taut as designed, resulting in a packaging bag with a flat surface and excellent wrinkle-free appearance. More specifically, compared to the film material of the bag body, the paper sleeve is more likely to expand in a high humidity environment and to shrink in a low humidity environment. Therefore, wrinkles may occur in the film material of the bag body, damaging the aesthetic appearance and deteriorating the appearance, but the sleeve of the present invention does not expand or shrink due to humidity changes and does not cause wrinkles in the film material. In addition, the sleeve contains a filler, which ensures sufficient rigidity and dead hold without making the sleeve excessively thick. This allows the three-dimensional shape of the packaging bag to be stably maintained without impairing transport efficiency. In addition, the filler contained in the sleeve acts as a heat seal inhibitor, making it easy to peel the sleeve from the bag body after use. In this way, the sleeve of the present invention combines polyolefin with a filler, and thus has water resistance, oil resistance, aesthetic appeal, rigidity, deadhold properties, and ease of releasability from the bag body.

[0034] [Packaging bag] The packaging bag of the present invention comprises a bag body and the sleeve of the present invention provided within the bag body. The sleeve of the present invention can give the packaging bag of the present invention a three-dimensional shape, and the packaging bag can be made self-supporting and stackable. The packaging bag of the present invention can adopt the same configuration as a known packaging bag that uses a sleeve, except that it comprises the sleeve of the present invention as the sleeve. Hereinafter, an example of the packaging bag of the present invention will be described with reference to Figs.

[0035] As shown in Fig. 3, the packaging bag 1 of the present embodiment includes a bag body 20 configured as a flat bag, and a sleeve 10 provided within the bag body 20. In the state shown in Fig. 3, the sleeve 10 is provided in a flat state within the bag body 20, and the packaging bag 1 as a whole is flat and does not have a three-dimensional shape.

[0036] The bag body 20 has a pair of opposing flat surfaces 21a, 21b formed by folding a single film material in half, and is configured so that a fold line 21c formed by folding becomes the lower end of the bag body 20. Heat-sealed sections 22a, 22b are formed on both side ends of the bag body 20, where the side ends of the flat surfaces 21a, 21b are heat-sealed and bonded together along the side ends. The top of the bag body 20 is open, and a zipper 23, which is a fastening member that freely opens and closes the upper opening, is attached to the inner surface of each of the flat surfaces 21a, 21b at the top of the bag body 20.

[0037] The zipper 23 is composed of a band-shaped male member 23a and a band-shaped female member 23b that engage with each other. The male member 23a is provided on the inner surface of one flat surface portion 21a so as to extend in the left-right direction of the bag body 20, and the female member 23b is provided on the inner surface of the other flat surface portion 3 so as to extend in the left-right direction of the bag body 20. It is preferable that the zipper 23 is not present in both the male member 23a and the female member 23b at a position corresponding to a portion where the lines extending from the fold lines 11a to 11d of the sleeve 10 intersect with the zipper 23, or a discontinuous portion is formed such that at least one of the male member 23a and the female member 23b is partially thin. The material of the zipper 23 may be any material that can be welded to the flat surfaces 21a and 21b, and examples of such materials include PE and PP.

[0038] In the bag body 20 in a flattened state, the sleeve 10 is provided such that the upper edge 13a of the sleeve 10 is a predetermined distance downward from the upper edge of the bag body 20, and the lower edge 13b of the sleeve 10 is a predetermined distance away from the lower edge of the bag body 20. Both side edges of the sleeve 10 in a flattened state, i.e., the portions where the fold lines 12a, 12b are formed, are configured to be located at the edges of the heat-sealed portions 22a, 22b of the bag body 20 in a flattened state.

[0039] The sleeve 10 in the bag body 20 is provided so as to contact the inner surfaces of the flat surfaces 21a, 21b of the bag body 20, and the sleeve 10 and the inner surfaces of the flat surfaces 21a, 21b are bonded to each other at the intended bonding portions 14a, 14b, and the intended bonding portions 14a, 14b become the bonding portions 14a, 14b. The sleeve 10 can be bonded to the inner surface of the bag body 20 by welding using heat sealing or by bonding using an adhesive, and the preferred embodiment is welding using heat sealing.

[0040] The film material constituting the bag body 20 may be a polyolefin film alone or a laminate having a base layer and a heat-sealing layer, as long as at least the inner surface of the film material is made of a heat-sealable polyolefin. The laminate may have an intermediate layer between the base layer and the heat-sealing layer.

[0041] Examples of the polyolefin constituting the polyolefin film or the heat-sealing layer include LDPE, MDPE, HDPE, LLDPE, PP, etc. One type of polyolefin may be used alone, or two or more types may be used in combination.

[0042] Examples of resin materials constituting the base layer include paper, polyethylene terephthalate, polyamide (nylon), PP, etc. As the base layer, a film made of one type of resin material may be used alone, or a film obtained by co-extrusion of two or more types of resin materials may be used. The thickness of the substrate layer is preferably 6 to 50 μm. The surface of the base layer is usually printed by gravure printing, flexographic printing, etc. The printing can be performed on the outer surface side, inner surface side, or both surfaces of the base layer.

[0043] The laminate may have an adhesive layer on the outer surface side of the bag body 20. By providing the adhesive layer, triangular portions 24b1 and 24b2, which will be described later, can be bonded by heat sealing. Examples of the manner in which the adhesive layer is formed include a manner in which a commercially available film having a heat seal layer on one side is used, and a manner in which a sealant is printed in advance (part coating) on ​​the places to be bonded.

[0044] The polyolefin constituting the heat-sealing layer may be the same as those mentioned above as the polyolefin constituting the polyolefin film. The thickness of the heat-sealing layer is preferably 6 to 50 μm.

[0045] The intermediate layer may be, for example, a layer intended to improve gas barrier properties, and specific examples thereof include metal foils and vapor-deposited films. The thickness of the intermediate layer is preferably 6 to 50 μm.

[0046] The packaging bag 1 can be formed from the flat bag state shown in FIG. 3 into a box shape as shown in FIGS. Specifically, as shown in Fig. 4, both sides of the packaging bag 1 are pressed inwardly of the packaging bag 1, and the sleeve 10 is folded at the fold lines 11a to 11d of the sleeve 10 to form a rectangular tube. As a result, the packaging bag 1 is formed with a front portion 2a, a back portion 2b facing the front portion 2a, and side portions 3a, 3b facing each other on both sides of the front portion 2a and the back portion 2b. At this time, above the upper edge 13a of the sleeve 10 in the bag body 20, an upper portion 24a is in a protruding state, the shape of which, as viewed from the front portion 2a, widens in the left-right direction as it goes upward. Also, below the lower edge 13b of the sleeve 10, triangular portions 24b1 are in a protruding state on each side of the side portion 3a, the shape of which, as viewed from the front portion 2a, is triangular. Below the lower edge 13b of the sleeve 10, on each side surface portion 3b side, a triangular portion 24b2 having a triangular shape when viewed from the front surface portion 3b side protrudes.

[0047] 5, each of the triangular portions 24b1 and 24b2 extending downward from the lower edge 13b of the sleeve 10 is folded toward the center of the packaging bag 1 along the lower edge 13b of the sleeve 10 and adhered to form a rectangular flat bottom portion 4. By forming the flat bottom portion 4, the packaging bag 1 becomes self-supporting as shown in FIG. The method of adhering the triangular portions 24b1, 24b2 is not particularly limited, and examples thereof include a method of applying an adhesive (adhesive) such as a hot melt agent to the portions, a method of applying a double-sided adhesive tape and pressing it, a part coat method in which the portions are heat-sealed using a sealant that has been applied in advance, and a heat seal method in which the portions are heat-sealed using a film having heat-sealing properties on one side.

[0048] 7, the upper portion 24a extending upward from the upper edge 13a of the sleeve 10 is folded along the upper edge 13a of the sleeve 10 toward the rear portion 2b of the packaging bag 1 with the upper portions of the front portion 2a and rear portion 2b overlapping each other. At this time, the heat-sealed portions 22a, 22b of the bag body 20 are folded toward the rear portion 2b. In this state, a flat surface is formed along the upper edge 13a of the sleeve 10 on the upper side of the bag body 20, and approximately triangular protruding portions 25a1, 25a2 extending toward the side portions 3a, 3b are formed.

[0049] 8, protruding portion 25a1 is folded downward at upper edge 13a of sleeve 10 and adhered to side surface portion 3a, and protruding portion 25a2 is folded downward at upper edge 13a of sleeve 10 and adhered to side surface portion 3b. This makes packaging bag 1 box-shaped. If zipper 23 has the aforementioned discontinuous portion, it will be easy to fold protruding portions 25a1 and 25a2 downward at upper edge 13a of sleeve 10. The method of adhering the protruding portions 25a1, 25a2 is not particularly limited, and examples thereof include a method of applying an adhesive (adhesive) such as a hot melt agent to the portions, a method of applying a double-sided adhesive tape and pressing it, a part coat method in which the portions are heat-sealed using a sealant that has been applied in advance, and a heat seal method in which the portions are heat-sealed using a film that has heat-sealing properties on one side.

[0050] The height of the packaging bag 1 formed in a box shape is approximately equal to the height of the sleeve 10. In the packaging bag 1 formed in a box shape, the front portion 2a, the back portion 2b, and the side portions 3a, 3b are all formed to be flat. In addition, by forming the sleeve 10 in a rectangular tubular shape within the bag body 20, the film material forming the bag body 20 is pulled by the sleeve 10 in each of the front portion 2a, the back portion 2b, and the side portions 3a, 3b, and is put into a tensed state, so that the formation of wrinkles is suppressed. In particular, it is preferable to provide adhesive parts for adhering the sleeve 10 to the inner surface of the bag body 20 on the opposing side portions 3a, 3b of the packaging bag 1 formed in a box shape, and not provide adhesive parts for adhering the sleeve 10 to the inner surface of the bag body 20 in the portions along the four fold lines 11a to 11d that separate the side portions, the side portions 3a, 3b, and the front portion 2a. By providing adhesive parts in areas other than along the fold lines 11a to 11d, when the sleeve 10 is formed into a rectangular tube shape inside the bag body 20, the bag body fixed by the adhesive parts provided on the side portions 3a and 3b can freely move at the portions where the four fold lines 11a to 11d contact the bag body. As a result, the packaging bag formed into a box shape is easily pulled from the front portion 2a and the back portion 2b toward the side portions 3a and 3b and is easily tensed. Even if there are wrinkles before being formed into a box shape, the wrinkles are eliminated, so that the formation of wrinkles in the box shape is suppressed. Examples of the adhesive means between the sleeve 10 and the bag body 20 include a heat sealing method. The positions of the adhesive parts (adhesive parts) 14a and 14b are not particularly limited, but as an example, it is preferable to provide them near the heat seal parts 22a and 22b on the side portions 3a and 3b. As a specific preferred example, in the example shown in Figure 1, band-shaped intended adhesive portions 14a, 14b are provided parallel to two fold lines 12a, 12b, starting at positions within a distance of 5 mm, and slightly shorter than the length of fold lines 12a, 12b, in order to assist in folding the sleeve 10 into a flat shape. In particular, in a sleeve having a window, it is preferable that wrinkles are not formed in the window, since this further improves visibility of the contents.

[0051] In the packaging bag 1 formed in a box shape, the three-dimensional shape is stably maintained by the sleeve 10, so that contents such as tea bags can be stored without losing their shape.

[0052] In the packaging bag of the present invention described above, the sleeve of the present invention, which has sufficient rigidity and dead-holding properties, gives the bag a three-dimensional shape when the contents are stored in it during use, ensuring excellent self-supporting and stacking properties. In addition, the sleeve of the present invention can be made thinner than plastic sleeves and paper sleeves to which no filler is added, so that the packaging bag of the present invention is less likely to become bulky in its flat state before it is used to store the contents, allowing more packaging bags to be stored in an outer container such as a cardboard box, and allowing the outer container to be smaller in size for packing a given number of packaging bags, resulting in excellent transport efficiency.

[0053] The dimensions of the paper sleeve are more susceptible to changes due to moisture in the air than the sleeve of the present invention containing added filler and the plastic sleeve without added filler. Therefore, in a high humidity environment, the paper sleeve expands, causing the packaging bag to bulge, and in a low humidity environment, the paper sleeve shrinks, causing the packaging bag to wrinkle, which can damage the aesthetic appearance. When wrinkles appear on the packaging bag due to dimensional changes in the paper sleeve, the wrinkles are more noticeable because the other parts of the packaging bag are smooth. In particular, the front design of the packaging bag is very important to users such as food manufacturers, so if there are wrinkles there, the product is more likely to be treated as defective. Thus, paper sleeves are originally used to form a smooth surface on the packaging bag to improve its aesthetic appearance, but there is a problem that the aesthetics are easily damaged due to dimensional changes caused by moisture. In contrast, the sleeve of the present invention, which contains added filler, does not change dimensions due to the humidity of the storage environment, and the bag body can be easily tensioned as designed to form a wrinkle-free, flat surface, so the packaging bag of the present invention has an excellent appearance and can be made to look better as a product.

[0054] Furthermore, in the packaging bag of the present invention, the sleeve can be easily peeled off from the bag body after use. Furthermore, since the packaging bag of the present invention has an excellent water resistance and oil resistance of the sleeve, it can also be used for storing contents that contain water or oil. Depending on the local government, even if a combination of a plastic sleeve and a plastic packaging bag is used, they may have to be separated when discarded. Even in such a case, the packaging bag of the present invention is easy to dispose of because the sleeve 10 is filled with a filler, and therefore the sleeve 10 and the packaging bag can be easily separated. Moreover, the packaging bag of the present invention can be easily peeled off from the bag body because the sleeve is filled with a filler.

[0055] The sleeve 10 has low gas permeability (in other words, high gas barrier properties) compared to a paper sleeve or a plastic sleeve to which no filler is added, and therefore has excellent preservation properties for the contents. A certain percentage of filler is added to the sleeve 10 of the present invention. The addition of the filler reduces the gas permeability slightly. For example, when a solid or powder content is filled in a packaging bag 1 having the sleeve 10 of the present invention, a packaging bag having a paper sleeve, and a packaging bag having a plastic sleeve to which no filler is added, the packaging bag 1 having the sleeve 10 of the present invention has the highest preservation properties for the contents, followed by the packaging bag having a plastic sleeve to which no filler is added, and the packaging bag having the paper sleeve has the lowest preservation properties. If the contents are solid or powder, they will not move within the bag during storage, so in the case of packaging bags equipped with paper sleeves in particular, deterioration of the contents (oxidation and moisture absorption) will begin from the parts in contact with the sleeve 10, and deterioration will gradually progress toward the center of the bag. On the other hand, the sleeve of the present invention is a sheet (coating) formed by mixing a filler with a certain ratio in polyolefin, and the filler is dispersed in the polyolefin in an island shape. When comparing the gas permeability of a plastic sleeve containing no filler, in which the molecular chains of polyolefin are entangled to form a coating, and the sleeve of the present invention in which the filler is dispersed in an island shape in the same coating, the sleeve of the present invention has a lower gas permeability. That is, when gas passes through the coating, in the sleeve of the present invention in which the filler is dispersed in an island shape, the gas bypasses the filler when passing through, so the path for the gas to pass through is long and the amount of gas passing through per unit time is small, so the gas permeability of the packaging bag 1 equipped with the sleeve 10 of the present invention is lower than that of a packaging bag equipped with a plastic sleeve not containing a filler and that of a packaging bag equipped with a paper sleeve. As a result, in the present invention, deterioration of the contents (oxidation and moisture absorption) can be suppressed, and the preservation of the contents is improved.

[0056] The packaging bag of the present invention is not limited to the above-described packaging bag 1. For example, the packaging bag of the present invention may include a sleeve other than sleeve 10 of the present invention. The bag body of the packaging bag of the present invention may be in the form of a tube, a three-side sealed bag, or a four-side sealed bag. Furthermore, the packaging bag of the present invention may have a configuration in which the bag body does not have a zipper. EXAMPLES

[0057] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description. [material] The materials used in this example are shown below. Film A: A 25 μm thick biaxially oriented polypropylene film with one heat-sealed surface and the other non-heat-sealed surface (corona-treated surface). Film B: A 50 μm thick linear low-density polyethylene film. Ink C: Printing ink for gravure printing. Adhesive D: Urethane adhesive for dry lamination.

[0058] [Example 1] The non-heat seal surface (corona treated surface) of film A was printed by gravure printing using ink C. Next, adhesive D was applied to the printed surface of film A, and film B was laminated by dry lamination to obtain a laminate consisting of film A (base layer) / printed layer / adhesive layer / film B (heat fusion layer). Next, the obtained laminate was folded in half so that the heat-sealing layer was on the inner surface, and both side edges were heat-sealed to prepare a three-sided bag having a height of 170 mm and a width of 215 mm. Next, a sleeve shown in Table 1 was inserted into the three-sided bag from the opening, and the adhesive part of the sleeve shown in Figure 1 and parts of the upper and lower peripheral parts of the front and back parts (not shown) were heat-sealed to the inner surface of the bag to obtain a packaging bag.

[0059] [Example 2, Example 3, Comparative Examples 1-2] Packaging bags were produced in the same manner as in Example 1, except that the sleeve used was changed to one shown in Table 1. However, Example 3 is a reference example.

[0060] [Table 1]

[0061] In Table 1, length L1 is the width between the creases that help fold the sleeve into a rectangular tube, length L2 is the width between the creases that help fold the sleeve into a rectangular tube and the creases that help fold the sleeve into a flat shape, and L4 is the height of the sleeve when it is in a rectangular tube shape (Figure 1). Length L3 is the width of the sleeve when it is flattened (L3=L1+2×L2).

[0062] [Evaluation method] (1) Packing test A test was conducted to see how many flattened packaging bags could be placed into a cardboard box with external dimensions of 470 mm length x 230 mm width x 190 mm height and internal dimensions of 460 mm length x 220 mm width x 175 mm height, and the number that could be placed was recorded.

[0063] (2) Rigidity test The sleeve used in each example was formed into a square tube shape, and with one open end of the square tube facing down, the sleeve was stood upright and a load was applied in the height direction to measure the strength until buckling. The evaluation results are shown in Table 2.

[0064] [Table 2]

[0065] As shown in Table 2, Examples 1 and 2, which used sleeves containing PP and talc, and Example 3, which used a sleeve containing calcium carbonate, were excellent in transport efficiency as a large number of packaging bags could be placed in a cardboard box, and also had sufficient rigidity to ensure self-supporting and stacking properties. On the other hand, in Comparative Example 1, in which a paper sleeve was used, the sleeve needed to be thick to obtain the same rigidity as the sleeves of Examples 1 to 3, so the number of packaging bags that could fit in the cardboard box was small, resulting in poor transportation efficiency. Also, in Comparative Example 2, in which a plastic sleeve not containing a filler was used, the sleeve needed to be thick to obtain the same rigidity as the sleeves of Examples 1 to 3, so the number of packaging bags that could fit in the cardboard box was small, resulting in poor transportation efficiency. [Industrial Applicability]

[0066] The sleeve of the present invention is used for packaging bags, has excellent water resistance and oil resistance, ensures sufficient rigidity and dead hold without being excessively thick, prevents deterioration of the appearance of the packaging bag, and can be easily peeled off from the bag body after use. The packaging bag of the present invention has sufficient self-supporting and stacking properties, has an excellent appearance, and the sleeve can be easily peeled off from the bag body after use. [Explanation of symbols]

[0067] 1...Packaging bag 2a…Front part 2b…Back part 3a, 3b…Side part 4…Bottom part 10. Sleeve 11a~11d…First fold 12a, 12b…Second fold 13a…upper edge 13b…lower edge 20…Bag body 21a, 21b...Plane part 22a, 22b...Heat seal section

Claims

1. A bag body having at least an inner surface made of a film material composed of polyethylene or polypropylene; a sleeve provided within the bag body so as to contact the inner surface of the bag body in a cylindrical state, giving the bag body a three-dimensional rectangular cylindrical shape and enabling the bag body to stand on its own and be stacked; a bonding portion at which the sleeve is bonded to the inner surface of the bag body by heat sealing; A packaging bag comprising: The bag body having a three-dimensional shape given by the sleeve is A front part and a back portion opposite the front portion; and side portions facing each other on both sides of the front portion and the rear portion, The sleeve contains a polyolefin and a filler, the polyolefin contained in the sleeve contains polyethylene and polypropylene, and the mass ratio of the polyethylene to the polypropylene is 0.05 or more and 19 or less; The content of the filler in the sleeve is 20% by mass or more and 75% by mass or less with respect to the total mass of the sleeve, The packaging bag has four first fold lines for assisting in folding the sleeve into a rectangular tube shape and two second fold lines for assisting in folding the sleeve into a flat shape, each of which is formed linearly on the surface of the sleeve so as to extend along the height direction when the packaging bag is self-supporting.

2. The packaging bag according to claim 1 , wherein the content of the filler is 51% by mass or more and 75% by mass or less with respect to the total mass of the sleeve.

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