triangular bag

Abstract

To provide a triangular bag with excellent oxygen barrier properties and anti-fogging capabilities, which can be manufactured at a lower cost than when using unstretched nylon and also offers superior transparency. [Solution] A triangular bag obtained by heat cutting a resin film, wherein the resin film contains biaxially oriented nylon.

Description

[Technical Field]

[0001] This invention relates to a triangular bag. [Background technology]

[0002] Various types of packaging bags are used to contain and preserve items. For example, triangular bags are sometimes used to reduce pressure on the items being preserved and to give them a soft, voluminous appearance.

[0003] Furthermore, when the items to be preserved are food products, it is required that these items be preserved while maintaining good quality, and packaging bags for achieving this purpose have been disclosed (see Patent Document 1).

[0004] For example, packaging materials used for fruits such as grapes require oxygen barrier properties to prevent oxygen permeation, in order to guarantee the quality of the food, such as its taste and freshness.

[0005] Furthermore, when contents are placed in a packaging bag and stored, moisture from the contents can cause fogging or condensation inside the bag, impairing its appearance. For example, there is a packaging bag for fruits and vegetables described in Patent Document 2. Patent Document 2 describes a multilayer film using a porous thermoplastic resin membrane layer having pores, and discloses how to impart anti-fogging properties to the surface of the multilayer film.

[0006] Nylon is one example of a resin film material used to make packaging bags with excellent oxygen barrier properties and anti-fogging properties. To date, unstretched nylon, which is particularly resistant to tearing, has been used. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-252718 [Patent Document 2] Japanese Patent Publication No. 2005-144830 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in recent years, a shortage of undrawn nylon has arisen, and the development of alternatives is desired. Furthermore, undrawn nylon has problems such as high cost and insufficient transparency.

[0009] This invention has been made in view of the above circumstances, and aims to provide a triangular bag that has excellent oxygen barrier properties and anti-fogging properties, can be manufactured at a lower cost than when using unstretched nylon, and has excellent transparency. [Means for solving the problem]

[0010] To solve the above problems, the present invention adopts the following configuration. [1] A triangular bag obtained by heat cutting a resin film, wherein the resin film contains biaxially oriented nylon. [2] The triangular bag according to [1], wherein the thickness of the resin film is 10 μm or more and 20 μm or less. [3] The triangular bag according to [1] or [2], wherein the resin film is a single-layer film. [4] The triangular bag described in any one of items [1] to [3], wherein the triangular bag is a bag for packaging grapes or fresh flowers. [5] The triangular bag according to any one of [1] to [4], wherein the ratio of the content of biaxially oriented nylon to the total mass of the resin film in the resin film is 90% by mass or more. [6] The triangular bag according to any one of [1] to [5], wherein the biaxially oriented nylon is one or more selected from the group consisting of 6-nylon, 66-nylon, and copolymers of 6-nylon and 66-nylon. [7] A triangular bag according to any one of items [1] to [6], wherein the haze of the resin film, as measured in accordance with JIS K 7136:2000, is 8% or less. [8]. The triangular bag according to any one of [1] to [7], wherein the tensile elastic modulus of the resin film measured in accordance with JIS K 7162 is 1000 MPa or more and 3000 MPa or less. [9]. The water vapor permeability of the resin film measured in accordance with JIS Z 0208 is 150 g / m 2 ·day or more. The triangular bag according to any one of [1] to [8].

[10] . The oxygen transmission rate of the resin film measured in accordance with JIS K 7126-2:2006 is 300 ml / (m 2 ·day·atm) or less. The triangular bag according to any one of [1] to [9]. [Advantages of the Invention]

[0011] According to the present invention, there is provided a triangular bag that is excellent in oxygen barrier properties and antifogging properties, can be manufactured at a lower cost than when using unstretched nylon, and is excellent in transparency. [Brief Description of the Drawings]

[0012] [Figure 1] It is a cross-sectional view schematically showing an example of a resin film constituting a triangular bag according to an embodiment of the present invention. [Figure 2] It is a diagram showing an example of a method for identifying a welded portion of a triangular bag according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view schematically showing an example of a triangular bag according to an embodiment of the present invention. [Figure 4] It is a diagram schematically showing an example of a method of using a triangular bag according to an embodiment of the present invention. [Modes for Carrying Out the Invention]

[0013] [[Resin Film]] The triangular bag according to an embodiment of the present invention is a triangular bag obtained by cutting and bag-making a resin film, and the resin film contains biaxially stretched nylon.

[0014] The present invention will be described in detail below with reference to the drawings. Note that, for convenience in making the features of the present invention easier to understand, the drawings may show enlarged versions of key parts, and the dimensional ratios of each component may not be the same as those in reality.

[0015] Figure 1 is a schematic cross-sectional view showing an example of the resin film that constitutes the triangular bag of this embodiment.

[0016] The resin film 1 contains biaxially oriented nylon. The inclusion of biaxially oriented nylon in the resin film 1 improves its oxygen barrier properties and anti-fogging properties. Furthermore, since biaxially oriented nylon is less expensive than unoriented nylon, the resin film 1 can be manufactured at a lower cost than when unoriented nylon is used. Additionally, since biaxially oriented nylon is more transparent than unoriented nylon, the transparency of the resin film 1 can be improved compared to when unoriented nylon is used.

[0017] Examples of biaxially oriented nylon include nylon obtained by polymerizing or copolymerizing a nylon salt obtained by the reaction of a cyclic lactam (a lactam with 3 or more ring members), an amino acid, or a diamine with a dicarboxylic acid, followed by a biaxial stretching treatment.

[0018] Examples of the cyclic lactams include ε-caprolactam, ω-enantractam, ω-laurolactam, α-pyrrolidone, and α-piperidone.

[0019] Examples of the aforementioned amino acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0020] Examples of the diamines that form the nylon salt include aliphatic amines such as tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 2,4,4-trimethylhexamethylenediamine; Examples include alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, isophorone diamine, piperazine, bis(4-aminocyclohexyl)methane, and 2,2-bis-(4-aminocyclohexyl)propane.

[0021] Examples of the dicarboxylic acid that forms the nylon salt include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sepatic acid, undecanedionic acid, and dodecanedionic acid; Examples include alicyclic carboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid.

[0022] More specifically, biaxially oriented nylon includes, for example, 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon, 6T-nylon, 6I-nylon, copolymers of 6-nylon and 66-nylon (nylon 6 / 66), copolymers of 6-nylon and 610-nylon, copolymers of 6-nylon and 611-nylon, copolymers of 6-nylon and 12-nylon (nylon 6 / 12), copolymers of 6-nylon and 612-nylon. Examples include copolymers of 6-nylon and 6T-nylon, copolymers of 6-nylon and 6I-nylon, copolymers of 6-nylon, 66-nylon and 610-nylon, copolymers of 6-nylon, 66-nylon and 12-nylon (nylon 6 / 66 / 12), copolymers of 6-nylon, 66-nylon and 612-nylon, copolymers of 66-nylon and 6T-nylon, copolymers of 66-nylon and 6I-nylon, copolymers of 6T-nylon and 6I-nylon, and copolymers of 66-nylon, 6T-nylon and 6I-nylon.

[0023] The nylon contained in resin film 1 may be of only one type, or it may be of two or more types. If there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

[0024] Biaxially oriented nylon is preferably one or more selected from the group consisting of 6-nylon, 12-nylon, 66-nylon, nylon 6 / 66, nylon 6 / 12, and nylon 6 / 66 / 12, in terms of heat resistance, mechanical strength, and availability, more preferably one or more selected from the group consisting of 6-nylon, 66-nylon, and nylon 6 / 66, and even more preferably 6-nylon from the viewpoint of low cost.

[0025] The resin film 1 may contain only biaxially oriented nylon (i.e., it may consist solely of biaxially oriented nylon), or it may contain biaxially oriented nylon and other components (which may be referred to as "other components" in this specification) (i.e., it may consist of biaxially oriented nylon and the other components).

[0026] The other components contained in the resin film 1 are not particularly limited and can be arbitrarily selected depending on the purpose, and may be, for example, resin components and non-resin components. The other components, which are resin components, are resins that do not fall under the category of biaxially oriented nylon (i.e., resins other than biaxially oriented nylon). The other component, which is a resin component, may be a homopolymer, which is a polymer of one monomer, or a copolymer, which is a polymer of two or more monomers.

[0027] Other non-resin components include, for example, additives known in the art. Examples of the aforementioned additives include antifogging agents, antioxidants, antistatic agents, nucleating agents, inorganic particles, viscosity reducers, viscosity thickeners, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and the like.

[0028] The other components contained in the resin film 1 may 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.

[0029] In resin film 1, the ratio of the content of biaxially oriented nylon (parts by mass) to the total mass (parts by mass) of resin film 1 ([Content of biaxially oriented nylon in resin film 1 (parts by mass)] / [Total mass (parts by mass) of resin film 1] × 100) is preferably 90% by mass or more, more preferably 95% by mass or more, and may be, for example, 97% by mass or more, or 99% by mass or more. By having the above ratio be equal to or above the lower limit, the oxygen barrier properties and anti-fogging properties of resin film 1 can be further improved, and resin film 1 can be manufactured at a lower cost. In addition, the transparency of resin film 1 can be further improved. On the other hand, the aforementioned ratio is 100% by mass or less. The aforementioned ratio is typically the same as the ratio of the content of biaxially oriented nylon (parts by mass) to the total content of components that do not vaporize at room temperature in the resin composition for forming resin films, as described later ([Content of biaxially oriented nylon in the resin composition for forming resin films (parts by mass)]) / [Total content of components that do not vaporize at room temperature in the resin composition for forming resin films (parts by mass)] × 100).

[0030] The resin film 1 may consist of one layer (single layer) or of two or more layers, but it is preferable that it consists of one layer (single layer) (it is a single-layer film). In this specification, even if the resin film 1 consists of two or more layers, if the composition of each layer cannot be clearly distinguished and the interface between layers cannot be recognized, the resin film 1 shall be considered to consist of one layer (single layer). By consisting of a single layer (one layer), the appearance of the resin film 1 can be further improved, and the cost can be further reduced. Furthermore, for example, if the resin film 1 is a laminated film formed by laminating a layer containing biaxially oriented nylon and a layer containing ethylene-vinyl alcohol copolymer (EVOH) in order to improve oxygen barrier properties, EVOH may be mixed as an impurity in the resin clumps (sometimes referred to as "resin balls" in this specification) that are generated at the welded portion obtained by cutting the resin films 1 together, which may reduce the seal strength of the resin film 1. In contrast, by consisting of a single layer (one layer), the impurities in the resin balls mentioned above do not mix in, and the seal strength of the resin film 1 can be further improved. When the resin film 1 consists of two or more 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.

[0031] The thickness of the resin film 1 is preferably 10 μm or more and 20 μm or less. The thickness of the resin film 1 is more preferably 12 μm or more and 18 μm or less, and even more preferably 13 μm or more and 17 μm or less. When the thickness of the resin film 1 is greater than or equal to the lower limit, the storage stability of the contents in the triangular bag made using the resin film 1 is further enhanced, and the ability to stably maintain the structure of the triangular bag is further enhanced. When the thickness of the resin film 1 is less than or equal to the upper limit, when the opening of the triangular bag made using the resin film 1 is twisted for use, the tendency for the opening to unwind over time can be further suppressed. In addition, the moldability of the resin film is further improved, and the heat-cutting of the resin film into bags becomes easier. Furthermore, the transparency of the triangular bag made using the resin film is further improved, making it easier to see the contents from the outside of the triangular bag. If the resin film 1 consists of multiple layers, it is preferable that the total thickness of these multiple layers is within the above numerical range.

[0032] All layers of the resin film 1 have transparency, and it is preferable that the resin film 1 has transparency, that is, the resin film 1 is a transparent resin film. In the triangular bag obtained by using such a resin film 1, the contents can be easily visually recognized through the resin film 1.

[0033] [Oxygen transmission rate] The oxygen transmission rate of the resin film 1 measured in accordance with JIS K 7126-2:2006 is, for example, 300 ml / (m 2 ·day·atm) or less, 250 ml / (m 2 ·day·atm) or less, 200 ml / (m 2 ·day·atm) or less, 160 ml / (m 2 ·day·atm) or less, 120 ml / (m 2 ·day·atm) or less, and 80 ml / (m 2 ·day·atm) or less may be any one of them. On the other hand, the oxygen transmission rate of the resin film 1 is 5 ml / (m 2 ·day·atm) or more. That is, the oxygen transmission rate of the resin film 1 is 5 to 200 ml / (m 2 ·day·atm), 5 to 160 ml / (m 2 ·day·atm), 5 to 120 ml / (m 2 ·day·atm), and 5 to 80 ml / (m 2 ·day·atm) may be any one of them. By setting the oxygen transmission rate of the resin film 1 to be below the above upper limit value, the greening, sprouting, and rooting of fruits and vegetables packaged in the triangular bag composed of the resin film 1 can be more effectively suppressed.

[0034] The oxygen transmission rate of the resin film 1 can be measured, for example, as the oxygen transmission rate per 24 hours in an atmosphere of 23 °C and 60% RH under the condition of a pressure of 1 atm for the resin film 1.

[0035] The oxygen permeability of the resin film 1 can be adjusted by adjusting the type, amount, or thickness of the components contained in any of the layers constituting the resin film 1. For example, the oxygen permeability of the resin film 1 can be easily adjusted by adjusting the type and amount of biaxially oriented nylon contained in the resin film 1.

[0036] [Moisture permeability] The moisture permeability of resin film 1, measured in accordance with JIS Z 0208 (cup method), is 150 g / m². 2 It is preferable to have a daily or higher dose, and the amount should be 150-350 g / m². 2 It is more preferable to be 200-300g / m². 2 It is even more preferable that it be a day. By setting the moisture permeability of the resin film 1 to be above the lower limit, the anti-fogging properties of the resin film 1 can be further improved. By setting the moisture permeability of the resin film 1 to be below the upper limit, the water vapor barrier properties of the resin film 1 can be further improved, and the deterioration of the freshness of the contents can be prevented.

[0037] The moisture permeability of the resin film 1 can be adjusted by adjusting the type, amount, or thickness of the constituent components in any of the layers constituting the resin film 1. For example, the moisture permeability of the resin film 1 can be easily adjusted by adjusting the type and amount of biaxially oriented nylon contained in the resin film 1.

[0038] [Tensile modulus of elasticity] The tensile modulus of resin film 1, measured in accordance with JIS K 7162, is preferably 1000 MPa or more and 3000 MPa or less, more preferably 1100 MPa or more and 2800 MPa or less, and even more preferably 2100 MPa or more and 2700 MPa or less. If the tensile modulus of the resin film 1 is above the lower limit, excessive softness of the resin film 1 is further suppressed, and the resin film 1 becomes less likely to bend even when bundled. If the tensile modulus of the resin film 1 is below the upper limit, the resin film 1 becomes softer, and when the opening of a triangular bag made using the resin film 1 is twisted for use, the unwinding of the opening is further suppressed.

[0039] The tensile modulus of resin film 1 can be measured, for example, as the tensile modulus of resin film 1 under conditions of a temperature of 20°C and a humidity of 50%.

[0040] The tensile modulus of resin film 1 can be adjusted by adjusting the type, amount, or thickness of the constituent components in any of the layers constituting resin film 1. For example, the moisture permeability of the resin film 1 can be easily adjusted by adjusting the type and amount of biaxially oriented nylon contained in the resin film 1.

[0041] [Hayes] The haze of resin film 1, measured in accordance with JIS K 7136:2000, is preferably 8% or less, more preferably 6% or less, and even more preferably 4% or less. By keeping the haze of the resin film 1 below the upper limit, the transparency of the resin film 1 is further improved, allowing the contents to be more clearly visible from the outside of the triangular bag constructed using the resin film 1. The lower limit of the haze of the resin film 1 is not particularly limited. For example, a resin film 1 with a haze of 0.5% or more can be manufactured more easily, and a resin film 1 with a haze of 2% or more can be manufactured even more easily. In one embodiment, the haze of the resin film 1 may be any of 0.5-8%, 0.5-6%, 0.5-4%, 3-8%, 3-6%, and 3-4%. However, these are just examples of the haze of the resin film 1.

[0042] The haze of the resin film 1 can be adjusted by adjusting the type, amount, or thickness of the constituent components in any of the layers constituting the resin film 1. For example, the haze of the resin film 1 can be easily adjusted by adjusting the type and amount of biaxially oriented nylon contained in the resin film 1.

[0043] <<Method for manufacturing resin film>> The resin film constituting the triangular bag of this embodiment can be manufactured, for example, by melt-extruding and molding a resin composition for forming a resin film, which is the material for forming the resin film, using an extruder.

[0044] Among the resin films that constitute the triangular bag of this embodiment, the laminated film (a resin film consisting of multiple layers) can be manufactured, for example, by a feed block method in which several extruders are used to melt-extrude the resin or resin composition that will form each layer, a co-extrusion T-die method such as a multi-manifold method, or an air-cooled or water-cooled co-extrusion inflation method.

[0045] Furthermore, the laminated film constituting the triangular bag of this embodiment can also be manufactured by coating the surface of another layer constituting the resin film with a resin or resin composition that will be the forming material for one of the layers, drying it as necessary to form a laminated structure within the resin film, and then further laminating other layers as needed to achieve the desired arrangement.

[0046] Furthermore, the laminated film constituting the triangular bag of this embodiment can also be manufactured by separately preparing two or more films in advance to form any two or more of the layers, laminating these films together using an adhesive by one of the following methods: dry lamination, extrusion lamination, hot melt lamination, or wet lamination, and further laminating other layers as needed to achieve the desired arrangement.

[0047] Furthermore, the laminated film constituting the triangular bag of this embodiment can also be manufactured by laminating two or more films that have been prepared separately in advance, without using adhesive, by a thermal lamination method or the like, and, if necessary, further laminating other layers in the desired arrangement.

[0048] Resin films manufactured by methods such as co-extrusion inflation tend to wrinkle easily when left in the air, but resin films manufactured by the co-extrusion T-die method tend to wrinkle less easily when left in the air. Therefore, it is preferable to manufacture resin films using the co-extrusion T-die method.

[0049] When manufacturing the resin film that constitutes the triangular bag of this embodiment, two or more of the methods for forming any of the layers (films) in the resin film described above may be combined.

[0050] Regardless of the manufacturing method, the resin composition that forms any of the layers in the resin film can be manufactured by adjusting the types and amounts of the constituent components so that the layer to be formed contains the desired components (constituent materials) in the desired amounts. For example, the ratio of the amounts of components that do not vaporize at room temperature in the resin composition is usually the same as the ratio of the amounts of those components in the layer formed from this resin composition.

[0051] Among the resin films, an example of a resin composition for forming the resin film 1 shown in Figure 1 (which may be referred to as the "resin film forming resin composition" in this specification) is a resin composition comprising the biaxially oriented nylon described above and, if necessary, the other components.

[0052] <<Triangular bag>> The triangular bag of this embodiment is a triangular bag obtained by heat cutting and forming the resin film described above. The triangular bag of this embodiment has a welded portion obtained by cutting the aforementioned resin films together. The triangular bag of this embodiment has a storage space formed by bonding a portion of a pair of resin films together.

[0053] The width of the welded portion of the triangular bag is preferably 300 μm or less. This ensures that even when multiple triangular bags are stacked, the overlapping edges do not become bulky.

[0054] Figure 2 shows an example of a method for identifying the welded portion of a triangular bag according to one embodiment of the present invention. The welded portion of the triangular bag can be identified by cutting it in the cross-sectional direction using a microtome "HM340E" manufactured by PHC Corporation, as shown in the principle diagram of the rotary microtome in Figure 2, and by observing it with a polarizing microscope "ECLIPSE LV100N POL" manufactured by Nikon Solutions Corporation, as shown in the magnified schematic diagram of the end of the triangular bag in Figure 2.

[0055] In the triangular bag of this embodiment, the width of the welded portion is the dimension of the welded portion in the direction perpendicular to its longitudinal direction, and if the width of the welded portion is not uniform, the maximum value of the width of the welded portion should be 300 μm or less.

[0056] The width of the welded portion is more preferably 280 μm or less, and even more preferably 250 μm or less. By keeping the width of the welded portion below the upper limit, the effect of preventing bulkiness at the overlapping ends when multiple triangular bags are stacked can be further improved. On the other hand, in terms of ease of manufacture, it is preferable that the width of the welded portion of the triangular bag be 10 μm or more.

[0057] The width of the welded portion can be adjusted by adjusting the type or content of components in any of the layers constituting the resin film. For example, the width of the welded portion can be easily adjusted by adjusting the type and content of biaxially oriented nylon contained in the resin film. The width of the welded portion can also be adjusted by adjusting the conditions for heat cutting and forming the resin film (conditions for forming the welded portion). For example, the width of the welded portion can be easily adjusted by changing the temperature of the cutting blade and the cutting time when heat cutting and forming the resin film.

[0058] For example, in order to easily adjust the width of the welded portion to the above range, the temperature of the cutting blade is preferably 410°C to 490°C, more preferably 420°C to 480°C, and even more preferably 430°C to 470°C.

[0059] Furthermore, the triangular bag of this embodiment, by being equipped with the aforementioned resin film, has good coloration at the welded joints between the resin films.

[0060] In the triangular bag of this embodiment, it is preferable that the welded portion has carbide fragments of the resin film. These carbide fragments are generated, for example, by the heat generated when the resin film is cut to form the bag. The presence of carbide fragments of the resin film in the welded portion makes it easier to pick up the welded portion. The statement that the welded portion has carbide fragments of the resin film means that some of the carbide fragments can be removed, but not all of them (for example, some of the carbide fragments are on the surface of the welded portion, and some are inside the welded portion).

[0061] The size of the carbide pieces is preferably 50 μm or more and 1000 μm or less, more preferably 55 μm or more and 900 μm or less, and even more preferably 60 μm or more and 800 μm or less. If the size of the carbide pieces is greater than or equal to the lower limit, the effect of making the welded portion easier to catch on and easier to pick up can be further improved. If the size of the carbide pieces is less than or equal to the upper limit, the problem of the welded portion catching too much and becoming difficult to pick up can be further suppressed, and the formation of pinholes in the welded portion can be further suppressed.

[0062] An identification image of the carbide fragment can be obtained, and the maximum length of the line segment connecting any two points located on the contour line in the identification image can be adopted as the size of the carbide fragment. The identification image can be obtained, for example, from imaging data when the welded portion is observed with an optical microscope.

[0063] The size of the carbide fragments can be adjusted by adjusting the type or content of components in any of the layers constituting the resin film. For example, the size of the carbide fragments can be easily adjusted by adjusting the type and content of biaxially oriented nylon contained in the resin film. The size of the carbide fragments can also be adjusted by adjusting the conditions for heat cutting and forming the resin film (conditions for forming the welded portion). For example, the size of the carbide fragments can be easily adjusted by changing the temperature of the cutting blade when heat cutting and forming the resin film.

[0064] For example, in terms of being able to easily adjust the size of the carbide pieces to the above range, the temperature of the cutting blade is preferably 410°C to 490°C, more preferably 420°C to 480°C, and even more preferably 430°C to 470°C.

[0065] The welded portion of a packaging bag obtained by heat-cutting a resin film containing biaxially oriented nylon is more prone to narrower widths and the presence of air bubbles than the welded portion of a packaging bag obtained by heat-cutting a resin film containing polyolefin resins such as polypropylene. Therefore, the strength of the welded portion (sometimes referred to as "heat-cutting strength" in this specification) of a packaging bag obtained by heat-cutting a resin film containing biaxially oriented nylon is weaker and more prone to variation than that of a packaging bag obtained by heat-cutting a resin film containing polyolefin resins such as polypropylene.

[0066] Furthermore, when manufacturing flat bags by heat cutting, the cutting blade may be applied from both the top and bottom of the resin film, whereas when manufacturing triangular bags by heat cutting, for example, a polytetrafluoroethylene sheet may be laid down, the resin film placed on top of it, and the cutting blade applied only from above the resin film. As a result, triangular bags tend to have weaker heat cutting strength and greater variability than flat bags.

[0067] On the other hand, as will be discussed later, when the contents are grapes, fresh flowers, leafy greens, citrus fruits, etc., they are often handled carefully. Therefore, for this purpose, the heat-sealing strength of a triangular bag made by heat-sealing a resin film containing biaxially oriented nylon is sufficient.

[0068] The cutting strength of the triangular bag measured by the method described in the examples below may be, for example, 5N / 15mm to 40N / 15mm, 5N / 15mm to 35N / 15mm, or 5N / 15mm to 30N / 15mm. The tear resistance of the triangular bag is further improved when the heat-cutting strength of the triangular bag is equal to or greater than the lower limit. A triangular bag with a heat-cutting strength equal to or less than the upper limit can be more easily produced.

[0069] The cutting strength of the triangular bag can be adjusted, for example, by adjusting the temperature of the cutting blade.

[0070] The volume of the storage space in the triangular bag is 0.0005 m³. 3 Above 0.03m 3 Preferably, it is 0.0010m 3 The above is 0.02m 3 It is more preferable that the following conditions be met: 0.0015m 3 Above 0.01m 3 The following is even more preferable:

[0071] Figure 3 is a schematic cross-sectional view showing an example of a triangular bag according to this embodiment. The triangular bag 10 shown here is formed using the resin film 1 shown in Figure 1. The triangular bag 10 has a storage space S formed by bonding a portion of a pair of resin films 1 together, and is generally constructed in this way. The storage space S of the triangular bag 10 contains the object to be preserved (not shown in the figure).

[0072] The triangular bag of this embodiment is not limited to the embodiments described above, and some components may be modified, deleted, or added without departing from the spirit of the present invention. For example, the triangular bag 10 shown in Figure 3 uses a pair of identical resin films 1,1, but the triangular bag of the present invention may use a pair of different resin films. Furthermore, the triangular bag of the present invention may have other components besides the resin film, as long as they do not impair the effects of the present invention. The other components are not particularly limited and may be appropriately selected depending on the purpose.

[0073] <<How to manufacture a triangular bag>> The triangular bag of this embodiment can be manufactured by using the resin film and bonding parts of the resin film together to create a storage space. Bonding of resin films can be performed by applying a known heat-sealing method. Furthermore, heat-sealed bag making refers to the process of melting a resin film with heat to seal it and shape it into a bag.

[0074] Figure 4 is a schematic diagram illustrating an example of how to use a triangular bag according to one embodiment of the present invention. The triangular bag may have a shape like an inverted trapezoid, for example, as shown in Figure 4. In this case, for example, the triangular bag can be manufactured by overlapping two resin films, cutting two points diagonally vertically to form the left end (sometimes referred to as the first side in this specification) and the right end (sometimes referred to as the second side in this specification), cutting one point horizontally to form the bottom end (sometimes referred to as the base in this specification), and making one opening to form the top end (sometimes referred to as the opening in this specification).

[0075] The temperature of the cutting blade during heat cutting and bag making is preferably 410°C to 490°C, more preferably 420°C to 480°C, and even more preferably 430°C to 470°C.

[0076] <<How to use the triangular bag>>

[0077] The triangular bag of this embodiment may be packaged after the contents are placed on a tray or the like, as shown in Figure 4, or it may be packaged without placing the contents on a tray or the like.

[0078] The triangular bag of this embodiment may be used after the contents have been packaged by twisting the opening of the triangular bag (which may be referred to as "back sealing" in this specification), or it may be used without twisting the opening of the triangular bag. Twisting the opening of the triangular bag is done to seal the opening. Whether or not the opening of the aforementioned triangular bag is twisted can be arbitrarily selected depending on the purpose.

[0079] The opening of the triangular bag is preferably twisted to the extent that oxygen does not move between the inside and outside of the bag via the twisted portion. Specifically, the angle of the twisted portion is preferably 180° to 720° (0.5 to 2.0 turns), more preferably 360° to 720° (1.0 to 2.0 turns), and even more preferably 540° to 720° (1.5 to 2.0 turns).

[0080] Examples of the contents include grapes, fresh flowers, leafy greens, and citrus fruits. Of these, grapes and fresh flowers are preferred, and grapes are more preferred.

[0081] For example, if the contents are grapes, fresh flowers, leafy greens, citrus fruits, etc., as shown in Figure 4, the triangular bag easily fits the shape of the contents (approximately an inverted triangle), resulting in less wrinkles and a firm, attractive appearance.

[0082] As mentioned above, triangular bags have weaker heat-sealing strength and are more prone to variation than flat bags. On the other hand, for example, when the contents are grapes, fresh flowers, leafy greens, citrus fruits, etc., these are often handled carefully, so the heat-sealing strength is sufficient for that application.

[0083] Furthermore, for example, if the contents are grapes or the like, mold will grow on the contents if water accumulates in the packaging bag, so strict control over humidity is necessary. On the other hand, the triangular bag of this embodiment is obtained by heat-cutting a resin film containing biaxially oriented nylon, and therefore has excellent oxygen barrier properties and anti-fogging properties, making it suitable for this application.

[0084] The amount of contents to be packaged in a triangular bag is equal to the volume of the triangular bag's storage space, which is 0.002 m³. 3 Preferably, the amount per unit is between 100g and 900g, more preferably between 150g and 850g, and even more preferably between 200g and 800g. [Examples]

[0085] 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.

[0086] [Example 1] <<Manufacturing of resin films>> A resin film with the configuration shown in Figure 1 was manufactured using the following procedure.

[0087] Biaxially oriented nylon (ONy, "Emblem" manufactured by Unitika Corporation) was prepared as the resin to make up the resin film.

[0088] A resin film (15 μm thick) was obtained by melt-extruding and molding the ONy at a die temperature of 260°C.

[0089] <<Evaluation of resin film>> <Measurement of oxygen permeability> The oxygen permeability of the above-mentioned resin film was measured in accordance with JIS K 7126-2:2006 under conditions of 23°C and 60% relative humidity (RH). The results are shown in Table 1.

[0090] <Measurement of moisture permeability> The moisture permeability of the above resin film was measured in accordance with JIS Z 0208 (cup method). The results are shown in Table 1.

[0091] <Measurement of Tensile Modulus> The tensile modulus of the above-mentioned resin film was measured in accordance with JIS K 7162 under conditions of 20°C and 50% humidity. The results are shown in Table 1.

[0092] <Measurement of haze> The haze (%) of the above resin film was measured in accordance with JIS K 7136:2000. The results are shown in Table 1.

[0093] <<Manufacturing of triangular bags>> The above resin film was cut and formed using a heat-sealing bag-making machine (heat-sealing blade temperature: 460°C), and a triangular bag was produced with a storage space formed by partially bonding the resin films together. Specifically, as shown in Figures 3 and 4, two of the above resin films were stacked, and two points were cut diagonally vertically to form the left end (first side) and right end (second side) of the bag, one point was cut horizontally to form the bottom end of the bag, and one point was opened to form the top end (opening), thereby manufacturing a triangular bag. The volume of the storage space in the triangular bag is 0.007 m³. 3 That was the case.

[0094] Using a microtome (HM340E, manufactured by PHC Corporation), the welded portion of the triangular bag was cut in the cross-sectional direction, and the width of the welded portion was measured by observing it with a polarizing microscope (ECLIPSE LV100N POL, manufactured by Nikon Solutions Corporation) and found to be 100 μm.

[0095] <<Evaluation of the triangular bag>> <Freshness preservation performance> Using the triangular bags described above, grapes (600g), fresh flowers (roses, 100g), leafy greens (spinach, 100g), and citrus fruits (mandarins, 400g) were each packaged, and the opening of each bag was twisted 540° (3 turns). They were stored in this state for 5 days, and the freshness was visually checked according to the following criteria. The results are shown in Table 1. (Evaluation Criteria) A: The freshness is well maintained. B: The freshness has not been properly maintained.

[0096] <Anti-fogging properties> The above-mentioned triangular bags were left to stand at 5°C for 60 minutes. Next, the triangular bags were visually inspected from the outside to confirm the visibility of the contents, and the anti-fogging properties inside the bags were evaluated according to the following criteria. The results are shown in Table 1. (Evaluation Criteria) A: No clouding is observed on the triangular bag, and the entire contents are clearly visible. B: Slight clouding is visible on the triangular bag, but the contents are still visible. C: Severe fogging is observed on the triangular bag, making it impossible to see at least part of the contents.

[0097] <Opening rewind> The opening of the above triangular bag was twisted 540° (3 turns). After 9 days, the triangular bag was cut with scissors, the cross-section was visually inspected, and the angle of the twist was measured to evaluate the degree of unwinding of the opening according to the following criteria. The results are shown in Table 1. (Evaluation Criteria) A: After 5 days, the angle of the twisted section is greater than 360°, and there is little unwinding of the opening. B: After 5 days, the angle of the twisted section is less than 360°, and there is a lot of unwinding at the opening.

[0098] <Measurement of thermal cutting strength> A test specimen with a width of 15 mm was cut from the region of the triangular bag obtained above, including the first side portion, and including both the heat-sealed portion and the unsealed portion. At this time, the length direction of the test specimen was aligned with the width direction of the triangular bag. The width of the triangular bag was defined as the dimension of the triangular bag in the same direction as the opening direction of the opening when the triangular bag was flattened in its thickness direction. 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 triangular bags, and the average value was adopted as the cutting strength (N / 15mm) of the heat-sealed portion on the first side. The results are shown in Table 1.

[0099] [Example 2] The resin film was manufactured and evaluated using the same method as in Example 1, except that the thickness of the resin film was changed from 15 μm to 25 μm. The triangular bag was also manufactured and evaluated using the same method as in Example 1. The results are shown in Table 1.

[0100] [Comparative Example 1] The resin film was manufactured and evaluated using the same method as in Example 1, except that unstretched nylon (CNy, "Rayfan" manufactured by Toray Industries, Inc.) was used as the resin constituting the resin film instead of ONy. A triangular bag was also manufactured and evaluated using the same method as in Example 1. The results are shown in Table 1.

[0101] [Comparative Example 2] The resin film was manufactured and evaluated using the same method as in Example 1, except that biaxially oriented polypropylene (OPP, "AF642" manufactured by Futamura Chemical Co., Ltd.) was used as the resin constituting the resin film instead of ONy. Triangular bags were also manufactured and evaluated using the same method as in Example 1. The results are shown in Table 1.

[0102] [Reference example 1] A resin film was manufactured and evaluated using the same method as in Example 1. The results are shown in Table 2.

[0103] <<Manufacturing of flat bags>> The above resin film was cut and formed using a heat-sealing bag-making machine (heat-sealing blade temperature: 460°C), and a flat bag was produced with a storage space formed by partially bonding the resin film pieces together. The volume of the storage space in the flat bag was 0.009 m³. 3 That was the case.

[0104] Using a microtome (HM340E, manufactured by PHC Corporation), the welded portion of the flat bag was cut in the cross-sectional direction, and the width of the welded portion was measured by observing it with a polarizing microscope (ECLIPSE LV100N POL, manufactured by Nikon Solutions Corporation) and found to be 300 μm.

[0105] <<Evaluation of flat bags>> The flat bags were evaluated using the same method as in Example 1. The results are shown in Table 2.

[0106] [Table 1]

[0107] [Table 2]

[0108] As is clear from the results above, in Example 1, since the constituent material of the resin film is ONy, it was possible to manufacture it at a lower cost than in Comparative Example 1 (constituent material: CNy). In Example 1, the oxygen permeability of the resin film was 30 ml / (m²). 2 Because the value is low (day·atm), Comparative Example 2 (oxygen permeability: 1000 ml / (m) 2 The triangular bags had better freshness preservation performance than the day / atm bags. In Example 1, the moisture permeability of the resin film was 250 g / m². 2 Because it is high (day), Comparative Example 2 (moisture permeability: 5g / (m 2 The anti-fog properties of the triangular bag were better than those of the day bag. In Example 1, although the tensile modulus of the resin film was high at 2400 MPa, the thickness of the resin film was thin at 15 μm, resulting in less unwinding of the triangular bag opening compared to Example 2. In Example 1, the transparency of the triangular bag was better than in Comparative Example 1 (haze: 6%) because the haze of the resin film was low at 4%. In Examples 1 and 2 and Comparative Example 1, the thermal cutting strength of the triangular bags was 4N / 15mm to 15N / 15mm, which was weaker than the thermal cutting strength of the triangular bag in Comparative Example 2 (20N / 15mm) and the thermal cutting strength of the flat bag in Reference Example 1 (18N / 15mm). However, since the contents of the triangular bags (grapes, fresh flowers, leafy greens, citrus fruits) are often handled carefully, the above thermal cutting strength was sufficient for these applications. [Industrial applicability]

[0109] This invention can be used to manufacture triangular bags that have excellent oxygen barrier properties and anti-fogging properties, can be manufactured at a lower cost than when using unstretched nylon, and have excellent transparency. [Explanation of symbols]

[0110] 1… Resin film 10…triangular bag S...Storage space in the triangular bag

Claims

1. A triangular bag obtained by heat cutting and forming a bag from a resin film, The aforementioned resin film is a triangular bag containing biaxially oriented nylon.

2. The triangular bag according to claim 1, wherein the thickness of the resin film is 10 μm or more and 20 μm or less.

3. The triangular bag according to claim 1 or 2, wherein the resin film is a single-layer film.

4. The triangular bag according to claim 1 or 2, wherein the triangular bag is a bag for packaging grapes or fresh flowers.

5. The triangular bag according to claim 1 or 2, wherein the ratio of the content of biaxially oriented nylon to the total mass of the resin film is 90% by mass or more.

6. The triangular bag according to claim 1 or 2, wherein the biaxially oriented nylon is one or more selected from the group consisting of 6-nylon, 66-nylon, and copolymers of 6-nylon and 66-nylon.

7. The triangular bag according to claim 1 or 2, wherein the haze of the resin film, as measured in accordance with JIS K 7136:2000, is 8% or less.

8. The triangular bag according to claim 1 or 2, wherein the tensile modulus of the resin film, as measured in accordance with JIS K 7162, is 1000 MPa or more and 3000 MPa or less.

9. The moisture permeability of the resin film, measured in accordance with JIS Z 0208, is 150 g / m². ２ A triangular bag according to claim 1 or 2, wherein it is 2 days or more in size.

10. The oxygen permeability of the resin film, measured in accordance with JIS K 7126-2:2006, was 300 ml / (m²). ２ A triangular bag according to claim 1 or 2, wherein the price is less than or equal to (day ATM).

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