Packaging bags

Abstract

To provide a packaging bag that can maintain the freshness of packaged food, has a sufficiently large depth dimension, and a bottom that is resistant to tearing. [Solution] A packaging bag 1 having a bottom 11 and both sides (first side 12, second side 13) formed by heat sealing of resin films 9, wherein the oxygen permeability of the resin film 9, measured in accordance with JIS K 7126-2:2006, is 1500 mL / (m²). 2 Packaging bag 1 is below (day·atm).

Description

[Technical Field]

[0001] This invention relates to packaging bags. [Background technology]

[0002] When storing and preserving foods such as fresh produce that have not undergone heat treatment, packaging bags are required to maintain the freshness of the food without compromising its quality. When storing fresh produce in packaging bags, a problem arises because the concentration of oxygen and carbon dioxide gases in the packaging bag changes due to the continuous respiration of the produce during storage. It is known that fresh produce respires more rapidly and is consumed more quickly when the oxygen concentration in the packaging bag is high. Therefore, various packaging bags and methods are being investigated to suppress these problems.

[0003] For example, a packaging bag for plant materials such as vegetables has been disclosed that has a specific range of water vapor permeability inherent to the material of the film constituting the packaging bag, and furthermore, has a specific range of oxygen permeability due to the pores in the film (see Patent Document 1).

[0004] On the other hand, a commonly used method for manufacturing packaging bags involves folding a long piece of resin film, which is the raw material, in half along its length, and then creating a sealed section by heat-sealing the folded resin film at regular intervals along its length, across its entire width. The sealed section is then cut while leaving the sealed section intact to obtain the packaging bag. This manufacturing method yields a packaging bag with sealed sections on both sides created by heat-sealing and a folded section of resin film at the bottom. This type of packaging bag is also called a two-sided bag. However, the depth of this two-sided bag coincides with the width of the folded resin film. Therefore, it is difficult to manufacture a packaging bag with a sufficiently large depth, and long items with large length dimensions are not suitable for storage.

[0005] On the other hand, two long resin films are overlapped, and one side portion of the long overlapped body is heat-sealed by thermocompression bonding, and at regular intervals in the length direction, wide thermocompression bonding is performed over the entire width direction to produce a sealed body. A manufacturing method of obtaining a packaging bag by cutting the sealed body while leaving a seal portion at this thermocompression bonding seal portion is also used. According to this manufacturing method, a packaging bag having seal portions formed by thermocompression bonding on both side portions and the bottom portion can be obtained, and this packaging bag is also called a three-sided bag. The depth direction of this three-sided bag coincides with the width direction of the above-mentioned long overlapped body, but in this manufacturing method, it is not necessary to fold the resin film, which is the raw material, in half along its length direction. Therefore, as a packaging bag, one with a sufficiently large dimension in the depth direction can be manufactured.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the seal strength of the thermocompression bonding seal portion of the packaging bag is not high enough to withstand the storage of relatively heavy weights. In particular, when packaging a long storage item, a large force is applied to the bottom of the packaging bag from the storage portion side. Therefore, when the bottom has a seal portion formed by thermocompression bonding, the packaging bag is likely to burst at the bottom, and there is a problem that the storage items are limited.

[0008] An object of the present invention is to provide a packaging bag capable of maintaining the freshness of the packaged food, having a sufficiently large dimension in the depth direction, and being difficult to burst at the bottom.

Means for Solving the Problems

[0009] To solve the above problems, the present invention adopts the following configuration. [1] A packaging bag having a bottom and both side portions formed by fusing and sealing resin films, wherein the oxygen transmission rate of the resin film, measured in accordance with JIS K 7126-2:2006, is 1500 mL / (m ·day·atm) or less. [2] When observing the cross-section of the packaging bag in the thickness direction of the resin film, the bottom has a块状 region, and the maximum value of the length of the line segment connecting two different points on the outer periphery of the块状 region is 6.5 times or more the thickness of the resin film at other parts that do not correspond to either the bottom or the both side portions of the packaging bag. The packaging bag according to [1]. [3] The depth of the storage portion of the packaging bag is 65 cm or more. The packaging bag according to [1] or [2].

[0010] [4] The packaging bag is for packaging daikon radish, long onion, sweet potato, celery or burdock. The packaging bag according to any one of [1] to [3]. [5] The resin film is a biaxially stretched polypropylene film. The packaging bag according to any one of [1] to [4]. [6] The water vapor transmission rate of the resin film, measured in accordance with JIS Z 0208 (cup method), is 3 g / m 2 ·day or more. The packaging bag according to any one of [1] to [5]. [Effect of the Invention]

[0011] According to the present invention, there is provided a packaging bag capable of maintaining the freshness of the packaged food, having a sufficiently large dimension in the depth direction and a bottom that is difficult to burst. [Brief Description of the Drawings]

[0012] [Figure 1] It is a front view schematically showing an example of a packaging bag according to an embodiment of the present invention. [Figure 2] It is an enlarged cross-sectional view schematically showing a region including the bottom of a packaging bag according to an embodiment of the present invention. ; [Figure 3]This is a schematic enlarged cross-sectional view showing a region including the side of a packaging bag according to one embodiment of the present invention. [Modes for carrying out the invention]

[0013] <<Packaging bag>> In one embodiment of the present invention, a packaging bag has a bottom and both sides formed by heat sealing of resin films, and the oxygen permeability of the resin film, measured in accordance with JIS K 7126-2:2006, is 1500 mL / (m²). 2 (•day•atm) is less than or equal to the following:

[0014] The packaging bag of this embodiment has an oxygen permeability of 1500 mL / (m²) of the resin film used as its manufacturing material. 2 The freshness of packaged food can be maintained by keeping the temperature below (day·atm). Furthermore, since the packaging bag of this embodiment does not require the resin film, which is the raw material for its manufacture, to be folded in half along its length during the manufacturing process, it is possible to make the depth dimension sufficiently large. Furthermore, since the bottom of the packaging bag in this embodiment is formed by heat sealing between resin films, the packaging bag is less likely to tear at the bottom even if a large force is applied to the bottom from the storage side.

[0015] When packaging (storing) long items in a packaging bag, a large force is applied to the bottom of the packaging bag from the storage side by the stored item. Therefore, conventional packaging bags, whose bottoms are formed by heat-sealing resin films, are prone to tearing at the bottom. In contrast, as described above, the packaging bag of this embodiment suppresses tearing at the bottom. In other words, the packaging bag of this embodiment is suitable for packaging (storing) long items.

[0016] Suitable long items to be packaged in the packaging bags of this embodiment include, for example, long fruits and vegetables such as radishes, leeks, yams, celery, and burdock. In other words, the packaging bag of this embodiment is preferably for packaging radishes, leeks, yams, celery, or burdock.

[0017] Figure 1 is a schematic front view showing an example of a packaging bag according to this embodiment. In addition, the diagrams used in the following explanation may be enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not be the same as in reality.

[0018] The planar shape of the packaging bag 1 shown here (the shape of the packaging bag 1 when it is flattened in the thickness direction) is rectangular. In the packaging bag 1, the bottom 11, the first side 12, and the second side 13 are all formed by heat-sealing the resin films 9 together. That is, the bottom seal portion 110 of the bottom 11 of the packaging bag 1, the first side seal portion 120 of the first side 12 of the packaging bag 1, and the second side seal portion 130 of the second side 13 of the packaging bag 1 are all heat-sealed portions.

[0019] In this specification, the "bottom of the packaging bag," the "first side of the packaging bag," and the "second side of the packaging bag" may be simply referred to as the "bottom," the "first side," and the "second side," respectively. Similarly, in this specification, the "bottom seal portion at the bottom of the packaging bag," the "first side seal portion at the first side of the packaging bag," and the "second side seal portion at the second side of the packaging bag" may be simply referred to as the "bottom seal portion," the "first side seal portion," and the "second side seal portion," respectively.

[0020] In the packaging bag 1, the end opposite the bottom 11 has an opening 14. In the packaging bag 1, the width W is determined by the bottom seal portion 110, the first side seal portion 120, and the second side seal portion 130. 10 The depth is D 10 A storage compartment 10 is formed.

[0021] When the packaging bag 1 is flattened in its thickness direction (the thickness direction of the resin film), the depth D of the storage section 10 of the packaging bag 110 is preferably 45 cm or more, more preferably 65 cm or more. Depth D 10 By having the lower limit value or more, even when packaging a long storage item, the effect of the packaging bag of this embodiment, that is, the suppression of bag breakage at the bottom, becomes more prominent. On the other hand, depth D 10 is preferably 100 cm or less in that its dimensions do not become excessive. Furthermore, the depth D of the storage part 10 10 is preferably adjusted appropriately according to the size of the object to be packaged (stored), particularly the length.

[0022] For example, when the object to be packaged is something with a particularly long length such as a long onion, the depth D of the storage part 10 10 is preferably 65 to 75 cm, more preferably 68 to 72 cm. For example, when the object to be packaged is something like a daikon radish, which has a medium length among long objects, the depth D of the storage part 10 10 is preferably 55 to 65 cm, more preferably 58 to 62 cm. For example, when the object to be packaged is something like a sweet potato, which has a length less than medium among long objects, the depth D of the storage part 10 10 is preferably 45 to 55 cm, more preferably 48 to 52 cm.

[0023] When the packaging bag 1 is flattened in its thickness direction, the width W of the storage part 10 10 is preferably 10 to 30 cm. And the width W of the storage part 10 10 is preferably adjusted appropriately according to the size of the object to be packaged (stored), particularly the width.

[0024] For example, when the object to be packaged is something with a wide width such as garlic, the width W of the storage part 10 10 is preferably 25 to 30 cm, more preferably 26 to 28 cm. For example, if the item to be packaged is of medium width, such as potatoes or onions, the width W of the storage section 10 will be... 10 The length is preferably 15-20 cm, and more preferably 17-19 cm. For example, if the item to be packaged is narrow, such as a leek, the width W of the storage section 10 will be... 10 It is preferably 10-15 cm, and more preferably 11-13 cm.

[0025] The bottom of the packaging bag in this embodiment typically has a distinctive shape. This is because the bottom is formed by heat sealing between resin films. Figure 2 is a schematic enlarged cross-sectional view showing the region including the bottom of the packaging bag of this embodiment. More specifically, this enlarged cross-sectional view is an enlarged cross-sectional view of the packaging bag in the thickness direction of the resin film constituting the packaging bag of this embodiment, and is an enlarged cross-sectional view of the packaging bag 1 shown in Figure 1 along the line A-A'. Here, we will explain using the bottom 11 of the packaging bag 1 shown in Figure 1 as an example. In Figures 2 and beyond, components identical to those shown in previously explained figures are denoted by the same reference numerals, and their detailed explanations are omitted.

[0026] The bottom 11 of the packaging bag 1 has a lumpy region 111. This is because the bottom 11 is formed by a heat-sealed bond between two resin films 9. Here, the cross-sectional shape of the lump-like region 111 at the bottom 11 of the packaging bag 1 is shown as a flattened circle with an asymmetrical shape in the direction of the flattening, and the tip (the outer edge of the packaging bag 1) being a convex surface. However, this is just one example, and the cross-sectional shape of the packaging bag in this embodiment is not limited to this. However, the cross-sectional shape shown here is typical. Furthermore, the surface of the heat-sealed portion is generally not a complex uneven shape, but rather a relatively smooth curved surface, and this is also true for the surface of the lump-like region 111.

[0027] In this specification, the "lumpy area at the bottom of the packaging bag" may be simply referred to as the "bottom lump area" or the "lumpy area." Similarly, in this specification, the "lumpy region on the first side of the packaging bag" described later may be simply referred to as the "first side lumpy region" or the "lumpy region," and the "lumpy region on the second side of the packaging bag" may be simply referred to as the "second side lumpy region" or the "lumpy region."

[0028] The size of the blocky region 111 is, for example, the maximum length L of the line segment connecting two different points on the outer circumference of the blocky region 111 in the cross-section. 111 It can be defined by (the length of the longest line segment). In the packaging bag 1, the maximum value L is set relative to the thickness W9 of the resin film 9 in a part other than the bottom 11 and both sides (i.e., the first side 12 and the second side 13). 111 The maximum value L is preferably 6.5 times or more, more preferably 10 times or more, and even more preferably 12.5 times or more. 111 However, by having a size above a certain value, the sealing strength of the bottom seal portion 110 of the bottom 11 of the packaging bag 1 is increased, and the effect of suppressing bag tearing at the bottom 11 of the packaging bag 1 is further enhanced. Note that the above maximum value L 111 The reason for using the thickness W9 of the resin film 9 as a comparison target, which is the thickness of the resin film 9 at a location other than the bottom 11, first side 12, and second side 13 of the packaging bag 1, is that the thickness W9 of the resin film 9 at the bottom 11 and both sides thereof (first side 12 and second side 13) may not be the original dimension, or it may be impossible to measure the exact dimension, due to the effect of heat sealing. In Figure 2, the value of the resin film 9 in a region relatively close to the bottom 11 is used as W9.

[0029] On the other hand, the maximum value L 111 It is preferable that the thickness is 31 times or less of the thickness W9 of the resin film 9. Such a bottom portion 11 (in other words, a lump-like region 111) can be formed more easily.

[0030] The sides of the packaging bag in this embodiment also typically have a characteristic shape. This is because the sides are formed by heat sealing of resin films. However, typically, the shape of the sides differs from the shape of the bottom. Figure 3 is a schematic enlarged cross-sectional view showing the region including the side portion of the packaging bag of this embodiment. More specifically, this enlarged cross-sectional view is an enlarged cross-sectional view of the packaging bag in the thickness direction of the resin film constituting the packaging bag of this embodiment, and is an enlarged cross-sectional view of the packaging bag 1 shown in Figure 1 along the line B-B'. Here, we will explain using the second side portion 13 of the packaging bag 1 shown in Figure 1 as an example.

[0031] The second side portion 13 of the packaging bag 1 also has a lumpy region 131, similar to the bottom portion 11. This is because the second side portion 13 of the packaging bag 1 is also formed by heat sealing between resin films 9. Here, the cross-sectional shape of the lump-like region 131 of the second side portion 13 of the packaging bag 1 is shown as a flattened circle with a concave tip (the outer edge of the packaging bag 1). However, this is just one example, and the cross-sectional shape of the packaging bag in this embodiment is not limited to this. However, the cross-sectional shape shown here is typical. Furthermore, the surface of the heat-sealed portion is generally not a complex uneven shape, but rather a relatively smooth curved surface, and this is also true for the surface of the second side portion 13.

[0032] The reason why the shape of the second side portion 13 differs in tendency from the shape of the bottom portion 11 is as follows. In other words, when the bottom portion 11 is formed, the portion separated from the bottom portion 11 by heat sealing is discarded, but when the second side portion 13 is formed, the portion separated from the second side portion 13 by heat sealing becomes the side portion (more specifically, the first side portion) of a different packaging bag from the packaging bag 1. Therefore, the heat sealing conditions of the resin film 9 are clearly different when the bottom portion 11 is formed and when the second side portion 13 is formed, and as a result, the shape of the second side portion 13 and the shape of the bottom portion 11 tend to be different from each other.

[0033] The size of the blocky region 131 is, for example, the maximum length L of the line segment connecting two different points on the outer circumference of the blocky region 131 in the cross-section. 131 It can be defined by (the length of the longest line segment). In packaging bag 1, of the line segments, the maximum value L 131 The longest line segment is identified, and in a direction perpendicular to the longest line segment, the length of the lump-shaped region 131 from the base 1311 on the storage side of the packaging bag 1 to the tip 1312 is X, and the length of the lump-shaped region 131 from the tip 1312 to the part of the longest line segment is Y. In this case, Y is preferably 0.3X or less, more preferably 0.28X or less, and even more preferably 0.26X or less. When the Y value is below the upper limit, the sealing strength of the second side seal portion 130 of the second side portion 13 of the packaging bag 1 is increased, and the effect of suppressing bag tearing at the second side portion 13 of the packaging bag 1 is enhanced. When the object to be packaged is wide, in particular when the opening 14 of the packaging bag is sealed by methods such as tying it with a string, a large force is applied to the second side portion 13 of the packaging bag 1 from the storage portion 10 side. In contrast, when the Y value is below the upper limit, bag tearing at the second side portion 13 becomes less likely.

[0034] On the other hand, Y is preferably 0.1X or greater. Such a second side portion 13 (in other words, a lumpy region 131) can be formed more easily.

[0035] If there are two possible Y values ​​in the aforementioned cross-section, it is preferable that the larger Y value satisfies the above-mentioned conditions.

[0036] In the packaging bag 1, the maximum value L is set relative to the thickness W9 of the resin film 9 in a part other than the bottom 11 and both sides (i.e., the first side 12 and the second side 13). 131 The maximum value L is preferably 5.5 times or more, more preferably 5.7 times or more, and even more preferably 5.9 times or more. 131However, by having a size above a certain value, the sealing strength of the second side seal portion 130 of the second side portion 13 of the packaging bag 1 is increased, and the effect of suppressing bag tearing at the second side portion 13 of the packaging bag 1 is further enhanced. Note that the above maximum value L 131 The reason for using the thickness W9 of the resin film 9 as a comparison target is the thickness of the resin film 9 at a location other than the bottom 11, first side 12, and second side 13 of the packaging bag 1, which is the maximum value L mentioned above. 111 The same applies as in the previous case. In Figure 3, W9 is the value of the resin film 9 in a region relatively close to the second side portion 13.

[0037] On the other hand, the maximum value L 131 It is preferable that the thickness of the resin film 9 is 16 times or less than the thickness W9. Such a second side portion 13 can be formed more easily.

[0038] The configurations of the first side portion 12 and the first side sealing portion 120 of the packaging bag 1 are the same as those of the second side portion 13 and the second side sealing portion 130 described above, and a detailed explanation of these is omitted here.

[0039] In terms of improving the freshness preservation function of food packaged in the aforementioned packaging bag, the oxygen permeability of the resin film is 1200 mL / (m²). 2 It is preferable that it be less than or equal to 900 mL / (m³) 2 It is more preferable that the value be less than or equal to the day / atm. On the other hand, the oxygen permeability of the resin film is 600 mL / (m²) in terms of its ability to maintain the freshness of food by suppressing anaerobic conditions. 2 It is preferable that it is 2000 days or more (atm). In one embodiment, the oxygen permeability of the resin film is 600 to 1500 mL / (m²). 2 (day·atm), 600-1200 mL / (m 2 (day·atm), and 600-900 mL / (m 2 It may be any of the following: ·day·atm. However, these are just examples of the oxygen permeability of the resin film.

[0040] The oxygen permeability of a resin film can be adjusted, for example, by adjusting the type and content of the components contained in the resin film. For instance, the oxygen permeability of a resin film can be easily reduced by selecting biaxially oriented polypropylene (OPP) as the resin film, or by increasing the proportion of biaxially oriented polypropylene in the resin film. In this way, by adjusting the types and amounts of components contained in the resin film, the oxygen permeability of the resin film can be easily adjusted without providing the through-holes described later in the resin film.

[0041] The oxygen permeability of the resin film can be adjusted, for example, by providing through holes in the resin film in the area forming the storage compartment within the packaging bag, and by adjusting the number and diameter of the through holes. The aforementioned through-hole penetrates the resin film in its thickness direction, from one surface to the other.

[0042] The shape of the opening of the through-hole in the resin film on the surface of the resin film, and the shape of the opening of the through-hole in a cross-section perpendicular to its longitudinal direction, are not particularly limited and may be, for example, circular or other shapes. However, a circular shape is preferable in terms of ease of forming the through-hole.

[0043] The average diameter of the through-holes in the resin film (the average value of the diameters of the through-holes) is preferably 50 to 200 μm, more preferably 55 to 190 μm, and even more preferably 60 to 180 μm. Having the average diameter of the through-holes within this range allows for a more suitable balance of oxygen gas, carbon dioxide gas, and water vapor concentrations within the storage area of ​​the packaging bag.

[0044] If the shape of the opening of the through-hole on the surface and cross-section of the resin film is other than circular, the diameter of the through-hole means the diameter of a circular opening that would have the same area as the area of ​​the non-circular opening.

[0045] The number of through-holes in the resin film (number of through-holes per unit area of ​​the resin film surface) is 1 to 100 holes / m². 2 Preferably, the number is 1 to 90 pieces / m 2 It is more preferable that the number be 1 to 80 per meter. 2 It is even more preferable that the number of through holes is within this range, which allows for a more balanced adjustment of the concentrations of oxygen gas, carbon dioxide gas, and water vapor within the storage compartment of the packaging bag.

[0046] The moisture permeability of the resin film, measured in accordance with JIS Z 0208 (cup method), was 3 g / m². 2 It is preferable that the film is of a certain quality (day or longer). In the storage compartment of a packaging bag obtained using such a resin film, fogging and condensation are prevented when the target item is stored inside, and a good appearance can be maintained.

[0047] In terms of achieving the above effects more significantly, the moisture permeability of the resin film is 3.5 g / m². 2 It is more preferable that it be 3.9 g / m² or more. 2 It is even preferable that it be 2 days or longer. On the other hand, the moisture permeability of the resin film is 12 g / m², which is suitable for preserving freshness by preventing food from wilting. 2 It is preferable that it be less than or equal to one day. In one embodiment, the moisture permeability of the film is 3 to 12 g / m². 2 • Day, 3.5-12 g / m² 2 • day, and 3.9-12 g / m² 2 It may be any of the following days. However, these are just examples of the moisture permeability of the resin film.

[0048] The moisture permeability of a resin film can be adjusted, for example, by adjusting the type and content of the components contained in the resin film. For example, by selecting biaxially oriented polypropylene (OPP) as the resin film, or by increasing the proportion of biaxially oriented polypropylene in the resin film, the oxygen permeability of the resin film can be easily reduced, and the moisture permeability of the resin film can be easily increased.

[0049] The moisture permeability of the resin film can be adjusted, for example, by providing through holes in the resin film in the area forming the storage compartment within the packaging bag, and by adjusting the number and diameter of the through holes. The through holes are as described above, and both their form and the form in which the through holes are provided in the resin film are as described above.

[0050] The moisture permeability of a resin film can be adjusted, for example, by adjusting the thickness of the resin film.

[0051] Resin film contains resin as its main component. The resin contained in the resin film is 1500 mL / (m²). 2 As long as an oxygen permeability of the resin film of less than or equal to (day·atm) can be achieved, it is not particularly limited.

[0052] The resin film may or may not contain non-resin components other than resin.

[0053] The resin and non-resin components contained in the resin film may each consist of only one type or two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

[0054] Preferred resins to be included in the resin film include, for example, polypropylene (PP) such as homopolypropylene (hPP), polypropylene random copolymer (rPP, propylene random copolymer), and polypropylene block copolymer (bPP, propylene block copolymer). In other words, the resin film preferably contains polypropylene.

[0055] Examples of non-resin components included in the resin film include various additives known in the field, such as antifogging agents, antiblocking agents, antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, viscosity reducers, viscosity thickeners, heat stabilizers, lubricants, infrared absorbers, and ultraviolet absorbers.

[0056] In a resin film, the ratio of the resin content to the total mass of the resin film ([resin content of the resin film (parts by mass)]) / [total mass of the resin film (parts by mass)] × 100) is preferably 80% by mass or more, and may be, for example, 90% by mass or more, or 95% by mass or more. By having the ratio be equal to or greater than the lower limit, a packaging bag that can better preserve the freshness of food can be produced. On the other hand, the aforementioned ratio is 100% by mass or less.

[0057] When the resin film contains polypropylene, the ratio of the polypropylene content to the total resin content in the resin film ([Polypropylene content in the resin film (parts by mass)]) / [Total resin content in the resin film (parts by mass)] × 100) is preferably 69% by mass or more, for example, it may be 74% by mass or more, or 79% by mass or more. By having the above ratio be equal to or greater than the above lower limit, a packaging bag that can better preserve the freshness of food can be produced. On the other hand, the aforementioned ratio is 100% by mass or less.

[0058] In other words, the resin film is preferably made of polypropylene, or is a polypropylene film (PP film) in which polypropylene is the main component (mainly contained component).

[0059] The resin film is preferably a biaxially oriented film. Biaxially oriented resin films have high strength and a good balance of oxygen permeability and moisture permeability within a suitable range, making them particularly suitable as the packaging bag of this embodiment. Furthermore, in terms of achieving these effects more effectively, it is preferable that the resin film be a biaxially oriented polypropylene film.

[0060] The resin film may consist of one layer (single layer) or of two or more layers. If the resin film consists of multiple layers, these layers may be identical or different, and the combination of these layers is not particularly limited as long as it does not impair the effects of the present invention.

[0061] In this specification, not only in the case of the resin film, "multiple layers may be identical or different from each other" means "all layers may be identical, all layers may be different, or only some layers may be identical." Furthermore, "multiple layers are different from each other" means "at least one of the constituent materials and thickness of each layer is different from each other."

[0062] The resin film is most suitable as the packaging bag of this embodiment because it has high strength, a good balance of oxygen permeability and moisture permeability within a suitable range, and these properties can be easily adjusted, and is biaxially oriented polypropylene film (OPP film), preferably with polypropylene as the main component.

[0063] The thickness of the resin film without through holes is not particularly limited, but is preferably 20 to 50 μm, more preferably 30 to 45 μm, and even more preferably 35 to 42 μm. The thickness of the resin film having the through holes is not particularly limited, but is preferably 20 to 55 μm, more preferably 30 to 45 μm, and even more preferably 35 to 42 μm. By keeping the thickness of the resin film within this range, it is possible to manufacture packaging bags that offer a good balance between food freshness preservation performance and seal strength at the heat-sealed portion, resulting in superior products. Here, "thickness of the resin film" refers to the total thickness of the resin film. For example, the thickness of a resin film consisting of multiple layers refers to the total thickness of all the layers that make up the resin film.

[0064] Resin films can be manufactured by known methods. For example, a resin film can be manufactured by forming a film (shaping into a film) a resin composition consisting of the aforementioned resin, or a resin composition containing the aforementioned resin and the aforementioned non-resin component, using a known method. A resin film having through holes can be manufactured by forming through holes in an unprocessed resin film that does not have through holes using known methods such as piercing it with a needle or irradiating it with a laser.

[0065] As described above, the packaging bag of this embodiment is resistant to tearing at the bottom even when a large force is applied to the bottom from the storage side. The resistance to tearing at the bottom of the packaging bag can be determined, for example, by measuring the seal strength of the bottom seal portion, as measured by the method described in the embodiment below.

[0066] For example, in the packaging bag of this embodiment, the seal strength at the bottom is preferably 17 N / 15 mm or more, more preferably 20 N / 15 mm or more, and even more preferably 22 N / 15 mm or more. The higher the seal strength at the bottom, the less likely the packaging bag is to tear at the bottom. On the other hand, the upper limit of the seal strength at the bottom is not particularly limited. For example, a packaging bag with a seal strength of 32 N / 15 mm or less can be more easily realized.

[0067] As described above, the packaging bag of this embodiment is designed to be difficult to tear on both sides, even when a large force is applied from the storage side. The resistance to tearing on both sides of the packaging bag can be determined, for example, by measuring the seal strength of the seal portions on both sides (first side seal portion, second side seal portion) using the method described in the embodiment below.

[0068] For example, in the packaging bag of this embodiment, the seal strength on both sides is preferably 15N / 15mm or more, more preferably 18N / 15mm or more, and even more preferably 20N / 15mm or more. The higher the seal strength on both sides, the less likely the packaging bag is to tear on both sides. On the other hand, the upper limit of the seal strength on both sides is not particularly limited. For example, a packaging bag with a seal strength of 30 N / 15 mm or less can be more easily realized.

[0069] In the packaging bag of this embodiment, the width (in other words, the seal width) of the heat-sealed portions at the bottom and both sides (for example, in the packaging bag 1 shown in Figure 1, the bottom seal portion 110 of the bottom 11, the first side seal portion 120 of the first side 12, and the second side seal portion 130 of the second side 13) is preferably 0.05 to 0.8 mm, more preferably 0.1 to 0.4 mm, and even more preferably 0.12 to 0.35 mm. When the width is greater than or equal to the lower limit, the seal strength is increased, and the effect of suppressing bag tearing at each part of the packaging bag is further enhanced. When the width is less than or equal to the upper limit, the width is avoided to be excessive.

[0070] <<Manufacturing method for packaging bags>> The packaging bag of this embodiment can be manufactured by a manufacturing method that includes a step of forming the bottom and both sides by heat-sealing resin films together. More specifically, when manufacturing the packaging bag, for example, two long resin films are overlapped with their lengths aligned to form an overlapping body, and one side of the overlapping body (one of the two sides in the length direction of the overlapping body) is heat-sealed to form the bottom portion of the packaging bag. Furthermore, the overlapping body is heat-sealed at regular intervals in the length direction along its entire width to form both sides of the packaging bag and simultaneously produce the desired packaging bag. The other side of the overlapping body that was not heat-sealed (the other of the two sides in the length direction of the overlapping body) becomes the end portion having the opening of the packaging bag.

[0071] The heat sealing temperature (e.g., the temperature of the heat cutting blade) when forming the bottom and both sides of the packaging bag is preferably 340 to 420°C, and more preferably 360 to 400°C. [Examples]

[0072] The present invention will be described in more detail below with reference to specific examples. However, the present invention is not limited in any way to the examples shown below.

[0073] [Example 1] <<Manufacturing of packaging bags using heat-sealed sealing>> Two rolls of biaxially oriented polypropylene film (OPP film, Futamura Chemical Co., Ltd. "AF-642", 40 μm thick) were prepared. This OPP film is a biaxially oriented film mainly composed of polypropylene, comprising a main layer mainly containing homopolypropylene and thin layers mainly containing polypropylene random copolymer provided on both sides thereof.

[0074] The oxygen permeability of this OPP film, measured in accordance with JIS K 7126-2:2006, is 750 mL / (m²). 2 It was a product of the same name (day·atm), and the packaging bags obtained using this method were capable of preserving the freshness of the packaged food. Furthermore, the moisture permeability of this OPP film, measured in accordance with JIS Z 0208 (cup method), is 4 g / m². 2 This method was used to prevent fogging and condensation in the storage compartment of the packaging bag, thus maintaining a good appearance.

[0075] Using a heat-sealing bag-making machine, long lengths of OPP film were fed from each of these rolls, and then these OPP films were overlapped with their lengths aligned to form an overlapping body. Next, one side of this long overlapping body was heat-sealed, and heat-sealing was also performed along its entire width at regular intervals along its length. At this time, the temperature of the heat-sealing blade was set to 380°C for all sections. The width of the heat-sealed sections was set to 0.12 mm for all sections. Based on the above, multiple packaging bags were manufactured that, when flattened, had a storage compartment (opening) width of 12 cm and a storage compartment depth of 70 cm.

[0076] <<Evaluation of packaging bags>> <Measurement of seal strength of the bottom seal area> A 15 mm wide test specimen was cut from the area including the bottom of the packaging bag obtained above, including both the heat-sealed and unsealed portions. At this time, the length of the test specimen was aligned with the depth of the storage compartment of the packaging bag. Using a tensile testing machine (TENSILON RTG-1310, manufactured by A&D Company, Limited), one strip of OPP film in the unsealed portion of the test specimen was fixed, and the other strip of OPP film was pulled along the length of the test specimen, with the angle between the two strips of OPP film set to 180°. The value where the variation in the peel strength was suppressed during this period was adopted as the peel strength. Furthermore, this measured value was converted to a value for when the width of the test specimen is 15 mm. This peel strength measurement and conversion calculation were performed on two packaging bags, and the average value was adopted as the seal strength (N / 15mm) of the bottom seal (heat-sealed portion). The results are shown in Table 1.

[0077] <Measurement of sealing strength of the seals on both sides> A 15 mm wide test piece was cut from the region of the packaging bag obtained above, including the first side portion, and containing both the heat-sealed portion and the unsealed portion. At this time, the length of the test piece was aligned with the width of the packaging bag. Using this test piece, the peel strength was measured in the same manner as for the heat-sealed portion of the bottom portion described above, and the seal strength (N / 15 mm) of the first side seal portion (heat-sealed portion) of the first side portion was calculated. The results are shown in Table 1. Furthermore, test specimens were similarly cut from the region including the second side of the packaging bag obtained above, and the peel strength was similarly measured using these specimens to calculate the seal strength (N / 15mm) of the second side seal portion (fusible seal portion) of the second side. The results are shown in Table 1.

[0078] <Check for any ruptures in the bag at the bottom and on both sides> The packaging bag obtained above was positioned with its bottom facing downwards in the vertical direction (opening facing upwards). A leek (mass 0.2 kg) was then dropped into the storage compartment of the packaging bag from a position 15 cm above the bottom, so that it would be stored in the storage compartment. Next, the bottom and both sides (first side and second side) of the packaging bag were visually inspected to check for any ruptures in these areas. The results are shown in Table 1.

[0079] <Calculation of the ratio of the size of the bottom lump region to the thickness of the resin film> Using a microtome (PHC HM340E), a cross-section was prepared in the thickness direction of the OPP film in the region including the bottom of the packaging bag obtained above. Then, using a polarizing microscope (Nikon Solutions ECLIPSE LV100N POL) at 230x magnification, the cross-section was observed and the ratio of the size of the bottom block region to the thickness of the resin film (OPP film) was calculated. The aforementioned ratio was calculated for two packaging bags, and the average value was formally adopted as the ratio of the size of the bottom lump region to the thickness of the resin film (OPP film). The results are shown in Table 1.

[0080] <Calculation of the ratio of the size of the bulky regions on both sides to the thickness of the resin film> Similar to the case of the bottom portion described above, a cross-section was prepared in the thickness direction of the OPP film in the region of the packaging bag obtained above, including its first side portion. Then, similar to the case of the bottom portion described above, the cross-section was observed and the ratio of the size of the first side portion to the thickness of the resin film (OPP film) was calculated. Furthermore, for the second side portion as well, the ratio of the size of the second side portion's bulky region to the thickness of the resin film (OPP film) was calculated. These results are shown in Table 1.

[0081] <Calculation of Y-values ​​in bilateral block-like regions> In the cross-section prepared as described above, the Y-values ​​were calculated for the first and second lateral bulk regions. The results are shown in Table 1.

[0082] [Comparative Example 1] <<Manufacturing of packaging bags using heat-seal sealing>> Two rolls of the same OPP film used in Example 1 were prepared, and a bag-making machine was used to unwind long lengths of OPP film from each roll. These OPP films were then overlapped with their lengths aligned to form an overlapping body. Next, one side of this long overlapping body was heat-sealed, and a sealed body was created by heat-sealing a wide (strip-shaped) portion of the entire width of the overlapping body at regular intervals along its length. The sealing temperature was set to 200°C and the sealing time to 0.5 seconds. The width of the heat-sealed portion was 10 mm on the side of the overlapping body and 20 mm in the width direction of the overlapping body. Furthermore, a guillotine blade was used to cut the sealed body at the heat-sealed portion in the width direction, leaving the sealed portion intact. Based on the above, we manufactured several comparative packaging bags that, when flattened, measured 12cm x 70cm, with a storage compartment (opening) width of 10cm and a storage compartment depth of 69cm.

[0083] <<Evaluation of packaging bags>> The comparative packaging bags obtained above were evaluated in the same manner as in Example 1. However, in this comparative example, since the sealing method of the resin film differed from that in Example 1, the ratio of the size of the bottom lump region to the thickness of the resin film, the ratio of the size of the side lump regions to the thickness of the resin film, and the Y value in the side lump regions were not calculated. The results are shown in Table 1.

[0084] [Table 1]

[0085] As is clear from the results above, in Example 1, the tearing of the packaging bag at the bottom of the package containing the green onions was suppressed. In Example 1, the sealing strength of the heat-sealed portion at the bottom was 27 N / 15 mm, and the ratio of the size of the bottom lump region to the thickness of the resin film was 13, both of which were sufficiently high. In the packaging bag of Example 1, the bottom was formed by a heat-sealed connection between resin films.

[0086] Furthermore, in Example 1, tearing of the packaging bag containing the green onions on both sides was also suppressed. In Example 1, the sealing strength of the heat-sealed portions on both sides was 24 N / 15 mm, and the ratio of the size of the bulky regions on both sides to the thickness of the resin film was 6, both of which were sufficiently high. Furthermore, in the bulky regions on both sides of Example 1, the Y value was 0.25X, which was within a favorable range. In the packaging bag of Example 1, both sides were also formed by heat sealing between resin films.

[0087] In contrast, in Comparative Example 1, the tearing of the packaging bag at the bottom of the package containing the green onions was not suppressed. In Comparative Example 1, the sealing strength of the heat-sealed portion at the bottom was 5 N / 15 mm. In the packaging bag of Comparative Example 1, the bottom was formed by heat-press sealing of resin films. [Industrial applicability]

[0088] The present invention can be used as a packaging bag for preserving the freshness of packaged food. [Explanation of symbols]

[0089] 1...Packaging bag 10. Storage compartment for packaging bags 11. Bottom of the packaging bag 12. First side of the packaging bag 13. Second side of the packaging bag 110...Bottom seal of the packaging bag 120...First side seal portion of the first side of the packaging bag 130...Second side seal portion of the second side of the packaging bag 111...Lumpy area at the bottom of the packaging bag 9. Resin film L 111 ...When observing a cross-section of the region including the bottom of the packaging bag, the maximum length of the line segment connecting two different points on the outer perimeter of the lumpy region at the bottom. W9... thickness of resin film D 10 ...depth of the storage compartment for the packaging bag

Claims

1. A packaging bag having a bottom and both sides formed by heat sealing of resin films, The oxygen permeability of the resin film, measured in accordance with JIS K 7126-2:2006, was 1500 mL / (m²). ２ Packaging bags that are below the following limits (day ATM).

2. When observing the cross-section of the packaging bag in the thickness direction of the resin film, The bottom portion has a blocky region, The packaging bag according to claim 1, wherein the maximum length of a line segment connecting two different points on the outer circumference of the lumpy region is 6.5 times or more the thickness of the resin film in other parts of the packaging bag that do not correspond to the bottom or the two sides.

3. The packaging bag according to claim 1 or 2, wherein the depth of the storage compartment of the packaging bag is 65 cm or more.

4. The packaging bag according to claim 1 or 2, wherein the packaging bag is for packaging radishes, leeks, yams, celery, or burdock.

5. The packaging bag according to claim 1 or 2, wherein the resin film is a biaxially oriented polypropylene film.

6. The moisture permeability of the resin film, measured in accordance with JIS Z 0208 (cup method), is 3 g / m². ２ - A packaging bag according to claim 1 or 2, which is 2 days or more in size.

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