Food packaging bags and methods for manufacturing food packaging bags

Abstract

To provide a package for food which has sufficient water vapor barrier property and is excellent in cost and productivity.SOLUTION: A package for food is used for packaging food and is formed of a packaging film for food, where a pore exists into which a coloring liquid is permeated by a capillary phenomenon when the coloring liquid is sprayed onto a heat seal part of the package for food from inside of the package for food.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to food packages and methods of using food packages. [Background technology]

[0002] Biaxially oriented polypropylene film (hereinafter, also referred to as OPP film) has an excellent balance of performance such as processability, water vapor barrier properties, transparency, mechanical strength, and rigidity, and is used as a packaging film for packaging food.

[0003] Examples of technologies relating to food packaging films using such OPP films include those described in Patent Document 1 (JP-A-2008-73926) and Patent Document 2 (JP-A-2004-82499).

[0004] Patent Document 1 describes a biaxially oriented multilayer polypropylene film characterized in that it has a layer of a propylene-α-olefin random copolymer (C) having a melting point in the range of 125 to 145°C on one side of a biaxially oriented film made of a propylene polymer composition containing 75 to 90% by weight of a propylene homopolymer (A) and 25 to 10% by weight of a tackifier (D), via a layer of a propylene-based polymer (B) having a melting point of 155°C or higher, and a layer of a propylene-based polymer (E) on the other side of the biaxially oriented film. Patent Document 2 describes that the biaxially oriented multilayer polypropylene film having the above-mentioned structure can suppress the seepage of petroleum resins and the like onto the film surface, and has excellent laminate strength and moisture resistance.

[0005] Patent Document 2 describes a multi-layer resin film having a polyvinyl alcohol resin layer on at least one surface of a biaxially oriented polypropylene resin layer containing 10 to 40% by weight of a highly crystallized resin and 6 to 15% by weight of a petroleum resin, the polyvinyl alcohol resin layer being further provided via an adhesive layer. The oxygen permeability at a relative humidity of 85% RH and a temperature of 23° C. is 600 mL / m 2·day·MPa or less, and the water vapor permeability at a relative humidity of 90% and a temperature of 40°C is 3.5g / m 2 The multilayer resin film is characterized in that the thickness of the film is 20 μm or less. Patent Document 2 describes that a multilayer resin film having the above-mentioned structure has excellent oxygen gas barrier properties and moisture resistance. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-73926 A [Patent Document 2] JP 2004-82499 A Summary of the Invention [Problem to be solved by the invention]

[0007] Although OPP film has water vapor barrier properties, it has poor heat sealability. Therefore, when using OPP film for food packaging such as food packaging bags, it is necessary to laminate a non-oriented polypropylene film (hereinafter also referred to as CPP film) that has excellent heat sealability to the OPP film. By further laminating a CPP film to the OPP film, the heat seal strength of the obtained food packaging is increased, the intrusion of moisture and oxygen into the sealed portion is suppressed, and the water vapor barrier property and oxygen barrier property of the food packaging can be improved. Here, since the OPP film and the CPP film have poor adhesion, it was necessary to laminate the CPP film onto the OPP film using an adhesive. Therefore, food packaging films using OPP film for food packaging products require many manufacturing steps because they include a step of further laminating the CPP film using an adhesive, and there was room for improvement in terms of simplifying the manufacturing process and reducing costs.

[0008] The present invention has been made in view of the above circumstances, and provides a food packaging material which has sufficient water vapor barrier properties, and is also excellent in terms of cost and productivity. [Means for solving the problem]

[0009] The present inventors conducted extensive research to solve the above problems, and as a result, they discovered that even food packaging having poor heat sealability, such as having pores in the heat-sealed parts through which a coloring liquid penetrates due to capillary action, has sufficient water vapor barrier properties and can be satisfactorily used as a food packaging, thereby completing the present invention.

[0010] That is, according to the present invention, there are provided a food package and a method of using the food package as described below.

[0011] [1] A food packaging body used for packaging food and made of a food packaging film, The food package has pores through which the coloring liquid penetrates due to capillary action when the coloring liquid is sprayed from inside the food package onto the heat-sealed portion of the food package. [2] In the food packaging material according to the above [1], A food packaging material, wherein the length of the coloring liquid that has permeated into the pores is 0.1 mm or more and 50 mm or less. [3] In the food packaging according to the above [1] or [2], The food packaging material, wherein the pores have a diameter of 0.05 mm or more and 5.0 mm or less. [4] In the food packaging material according to any one of the above [1] to [3], The food packaging film comprises a biaxially oriented film layer composed of a propylene polymer composition containing a propylene polymer, and a heat seal layer provided so as to be in direct contact with at least one surface of the biaxially oriented film layer, The food packaging material, wherein the heat seal layer is the outermost layer, and the thickness of the heat seal layer is 0.1 μm or more and 10 μm or less. [5] In the food packaging material according to the above [4], The food packaging material, wherein the heat seal layer is a single layer. [6] In the food packaging according to the above [4] or [5], The food packaging material wherein the heat seal layer is biaxially stretched. [7] In the food packaging material according to any one of the above [4] to [6], The food packaging material, wherein the heat seal layer comprises at least one member selected from a propylene / α-olefin random copolymer and a propylene homopolymer. [8] In the food packaging material according to any one of the above [4] to [7], A food package, wherein the ratio of the thickness of the biaxially oriented film layer to the total thickness of the food packaging film is 0.50 or more and 0.998 or less. [9] In the food packaging according to any one of [1] to [8] above, The food package wherein the food comprises a dried food.

[10] In the food packaging material according to the above [9], A food packaging material in which the water activity of the dried food is 0.05 or more and 0.3 or less.

[11] In the food packaging according to any one of the above [1] to

[10] , Food packaging used as an outer packaging bag.

[12] A method for using the food packaging body described in any one of [1] to [8] above as a packaging body for dried food.

[13] In the method of using the food packaging material according to the above

[12] , A method for using the food packaging material, in which the water activity of the dried food is 0.05 or more and 0.3 or less.

[14] In the method of using the food packaging material according to the above

[12] or

[13] , The food packaging material is used as an outer packaging bag. Effect of the Invention

[0012] According to the present invention, it is possible to provide a food packaging material that has sufficient water vapor barrier properties and is also excellent in terms of cost and productivity. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a schematic example of the structure of a food packaging film for forming a food package according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic diagrams and do not correspond to the actual dimensional ratio. Note that "~" between numbers in the text indicates "above" to "below" unless otherwise specified.

[0015] <Food packaging> The food packaging body according to the present embodiment is a food packaging body used for packaging food and made of a food packaging film, and when a coloring liquid is sprayed from inside the food packaging body onto the heat-sealed portion of the food packaging body, there are pores through which the coloring liquid penetrates by capillary action. The food packaging body according to the present embodiment is, for example, a packaging bag itself used for the purpose of containing food, or a bag containing food. In addition, the packaging form of the food packaging body according to the present embodiment includes, for example, a three-sided bag, a four-sided bag, a pillow bag, a palm bag, a stick bag, a gusset bag, a standing pouch, etc., having a heat-sealed portion formed by heat fusion on all or part of the periphery. In addition, an oxygen absorber or the like may be placed inside the food packaging body in addition to the food. Here, the coloring liquid may be Ageless Seal Check Spray (red penetrating liquid, manufactured by Mitsubishi Gas Chemical Co., Ltd.) When Ageless Seal Check Spray is sprayed onto the heat-sealed portion from the inside of the food packaging, the red liquid seeps out from the pores, making it possible to confirm the pores into which the coloring liquid has penetrated.

[0016] Here, in the past, food packaging materials with poor heat sealability, such as those with pores in the heat seal portion through which a coloring liquid penetrates due to capillary action, were considered to have poor water vapor barrier properties due to their poor sealing properties, and were not adopted as products and were discarded as defective items during the manufacturing process. However, according to the studies of the present inventors, it has been surprisingly found that even such food packaging materials have sufficient water vapor barrier properties and can be used satisfactorily as food packaging materials. Here, the food packaging body according to this embodiment has inferior oxygen barrier properties compared to packaging bodies with excellent sealing properties, but exhibits sufficient water vapor barrier properties, and is therefore particularly suitable for use as a food packaging body for packaging foods (e.g., dried foods) that require water vapor barrier properties but not so much oxygen barrier properties. In addition, the food packaging according to the present embodiment can be produced by, for example, omitting the step of further laminating a CPP film having excellent heat sealing properties using an adhesive, and by carrying out heat sealing under a wide range of sealing temperature and pressure conditions, which results in excellent cost and productivity. As described above, according to this embodiment, it is possible to provide a food packaging body that has sufficient water vapor barrier properties, and is also excellent in terms of cost and productivity.

[0017] In the food packaging of this embodiment, the length of the coloring liquid that has penetrated into the pores is preferably 0.1 mm or more, more preferably 1 mm or more, and even more preferably 3 mm or more, from the viewpoint of productivity of the food packaging, and is preferably 50 mm or less, more preferably 30 mm or less, even more preferably 25 mm or less, even more preferably 20 mm or less, and particularly preferably 10 mm or less, from the viewpoint of water vapor barrier property.

[0018] In the food packaging body of this embodiment, the pore size of the above-mentioned pores is preferably 0.001 mm or more, more preferably 0.01 mm or more, even more preferably 0.05 mm or more, and particularly preferably 0.1 mm or more, from the viewpoint of productivity of the food packaging body, and is preferably 5.0 mm or less, more preferably 4.0 mm or less, even more preferably 3.0 mm or less, even more preferably 2.0 mm or less, and particularly preferably 1.0 mm or less, from the viewpoint of water vapor barrier property.

[0019] The food packaging body according to this embodiment can exhibit sufficient water vapor barrier properties even for dried foods, for which water vapor barrier properties are particularly required, and therefore can be particularly suitably used as a packaging body for packaging foods, including dried foods. Here, the dried food according to the present embodiment refers to food in a dry or semi-dried state (including pet food). Here, a dry food refers to a food with a moisture content of 15% by mass or less, and a semi-dried food refers to a food with a moisture content of more than 15% by mass and less than 50% by mass. Examples of dried foods include nuts, snack foods, cereal foods, luxury foods, dried noodles and pastas, grains and flours, dried vegetables, confectioneries, rice crackers, dairy products, and seasonings. Among these, from the viewpoint of obtaining the effects of this embodiment more effectively, it is preferable for the dried food to include rice crackers, and it is more preferable for the dried food to include dried rice crackers and dried beans coated with soy sauce, or rice crackers that are not coated with soy sauce on the surface. In order to more effectively obtain the effects of this embodiment, the water activity of the dried food is preferably 0.05 or more and 0.3 or less.

[0020] The food packaging body according to this embodiment is preferably used as an outer packaging bag that requires water vapor barrier properties. Furthermore, when the food packaging according to the present embodiment is used in an integrated package consisting of food, individual packaging bags for individually packaging the food, and an outer packaging bag for packaging a plurality of the individual packaging bags, the food packaging according to the present embodiment is preferably used in the outer packaging bag for which water vapor barrier properties are required in the integrated package, thereby making it possible to obtain an integrated package having sufficient water vapor barrier properties.

[0021] <Food packaging film> FIG. 1 is a cross-sectional view showing a schematic example of the structure of a food packaging film 100 for forming a food package according to an embodiment of the present invention. The food packaging film 100 according to this embodiment may be, for example, a film including a biaxially stretched film layer 101 made of a propylene polymer composition containing a propylene polymer, and a heat seal layer 103 provided so as to be in direct contact with at least one surface of the biaxially stretched film layer 101. Here, the heat seal layer 103 is the outermost layer, and the thickness of the heat seal layer 103 is preferably 0.1 μm or more and 10 μm or less. In this embodiment, when the heat seal layer 103 is provided on both sides of the biaxially stretched film layer 101, the above thickness of the heat seal layer 103 indicates the thickness of the heat seal layer 103 provided on one side of the biaxially stretched film layer 101.

[0022] As described above, OPP film has water vapor barrier properties but poor heat sealability. Therefore, when OPP film is used for food packaging such as food packaging bags, it is necessary to laminate a CPP film or the like having excellent heat sealability on the OPP film. By further laminating a CPP film on the OPP film, the heat seal strength of the obtained food packaging is increased, the intrusion of moisture and oxygen into the sealed portion is suppressed, and the water vapor barrier properties and oxygen barrier properties of the food packaging can be improved. Here, since the OPP film and the CPP film have poor adhesion, it was necessary to laminate the CPP film onto the OPP film using an adhesive. Therefore, food packaging films using OPP film for food packaging products require many manufacturing steps because they include a step of further laminating the CPP film using an adhesive, and there was room for improvement in terms of simplifying the manufacturing process and reducing costs.

[0023] On the other hand, in the food packaging film 100 according to the present embodiment, since the heat seal layer 103 can be formed directly on the biaxially stretched film layer 101, there is no need to perform a step of further laminating the CPP film using an adhesive as in the case of a laminated film of an OPP film and a CPP film, and the manufacturing process can be simplified, thereby improving productivity. In addition, since there is no need to use a CPP film, costs can be reduced.

[0024] Here, food packages made using the food packaging film 100 according to this embodiment have poor oxygen barrier properties due to low heat seal strength and poor sealing properties compared to food packages made using a laminated film of an OPP film and a CPP film, but surprisingly, despite the poor sealing properties, they exhibit sufficient water vapor barrier properties. Therefore, they can be particularly suitably used as a film constituting a food package for packaging foods (e.g., dried foods) that require water vapor barrier properties but not so much oxygen barrier properties.

[0025] The thickness of the food packaging film 100 in this embodiment is not particularly limited, but can be set arbitrarily depending on the desired objectives such as water vapor barrier properties, cost, mechanical strength, transparency, etc., and is not particularly limited, but is usually 5 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less, and more preferably 15 μm or more and 40 μm or less. When the thickness of the food packaging film 100 is within the above range, the balance of mechanical properties, handling properties, appearance, formability, lightweight properties, and the like is excellent.

[0026] Each layer constituting the food packaging film 100 will be described below.

[0027] [Biaxially oriented film layer] The biaxially oriented film layer 101 (also referred to as a biaxially oriented polypropylene-based film layer) in this embodiment is formed, for example, by biaxially stretching a film composed of a propylene polymer composition containing a propylene polymer.

[0028] The thickness of the biaxially stretched film layer 101 in this embodiment is not particularly limited as it can be set arbitrarily depending on the desired objectives such as water vapor barrier properties, cost, mechanical strength, transparency, etc., but is usually 10 μm or more and 100 μm or less, preferably 15 μm or more and 75 μm or less, and more preferably 20 μm or more and 50 μm or less. When the thickness of the biaxially stretched film layer 101 is within the above range, the balance of mechanical properties, handling properties, appearance, moldability, lightweight properties, and the like is excellent.

[0029] The biaxially stretched film layer 101 according to this embodiment may be a single layer, or may be a laminate of multiple layers made of a propylene polymer composition, but it is necessary that it is biaxially stretched.

[0030] In addition, in the food packaging film 100, the ratio of the thickness of the biaxially oriented film layer 101 to the overall thickness of the food packaging film 100 is preferably 0.50 or more and 0.998 or less, more preferably 0.60 or more and 0.99 or less, more preferably 0.70 or more and 0.97 or less, and even more preferably 0.75 or more and 0.95 or less.

[0031] (Propylene polymer composition) The propylene polymer composition according to this embodiment includes a propylene polymer. The content of the propylene polymer in the propylene polymer composition according to this embodiment, i.e., the biaxially stretched film layer 101, is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, still more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, when the entire propylene polymer composition is taken as 100% by mass. This makes it possible to achieve a better balance of water vapor barrier properties, mechanical properties, handleability, appearance, moldability, etc.

[0032] (Propylene polymer) Examples of the propylene polymer according to the present embodiment include propylene homopolymers and copolymers of propylene and ethylene or α-olefins having 4 to 20 carbon atoms. Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Among these, ethylene or α-olefins having 4 to 10 carbon atoms are preferred, and ethylene is more preferred. These α-olefins may form random copolymers or block copolymers with propylene. The content of the structural units derived from ethylene or α-olefins having 4 to 20 carbon atoms is preferably 5 mol % or less, and more preferably 2 mol % or less, when the entire propylene polymer is taken as 100 mol %. The propylene polymer in the biaxially stretched film layer 101 may be used alone or in combination of two or more kinds. Among these, from the viewpoint of obtaining a biaxially stretched film layer 101 having a better balance of properties such as heat resistance, water vapor barrier property, mechanical properties, and rigidity, a propylene homopolymer is preferred as the propylene polymer.

[0033] The propylene polymer according to the present embodiment can be produced by various methods, for example, by using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0034] The melt flow rate (MFR) of the propylene polymer, measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and even more preferably 2 g / 10 min or more, from the viewpoints of fluidity and moldability, and is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, and even more preferably 7 g / 10 min or less, from the viewpoint of further stabilizing moldability.

[0035] (Other Ingredients) To the propylene polymer composition according to the present embodiment, various additives such as a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slipping agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler may be added as necessary within a range that does not impair the object of the present embodiment.

[0036] (Method for preparing propylene polymer composition) The propylene polymer composition according to the present embodiment can be prepared by mixing or melt-kneading the components using a dry blend, a tumbler mixer, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder, a heat roll, or the like.

[0037] [Heat seal layer] In order to impart heat sealability to the food packaging film 100 according to this embodiment, a heat seal layer 103 is provided as an outermost layer on at least one surface of a biaxially oriented film layer 101. The heat seal layer 103 may be provided on both surfaces of the biaxially oriented film layer 101.

[0038] In the food packaging film 100, the thickness of the heat seal layer 103 is preferably 0.1 μm to 10 μm, more preferably 0.2 μm to 9 μm, further preferably 0.5 μm to 8 μm, and particularly preferably 1 μm to 8 μm. Here, the thickness of the heat seal layer 103 refers to the thickness of the heat seal layer 103 provided on one side of the biaxially stretched film layer 101. When the thickness of the heat seal layer 103 is equal to or greater than the above lower limit, the heat sealability of the food packaging film 100 can be improved. Furthermore, by having the thickness of the heat seal layer 103 be equal to or less than the above upper limit, the adhesion to the biaxially oriented film layer 101 is improved, and it becomes possible to laminate the heat seal layer 103 on the biaxially oriented film layer 101 without using an adhesive. That is, since it becomes possible to provide the heat seal layer 103 so as to be in direct contact with the surface of the biaxially oriented film layer 101, it is possible to simplify the manufacturing process of the food packaging film 100, i.e., the manufacturing process of the food package according to this embodiment.

[0039] In the food packaging film 100, the heat seal layer 103 provided on one side is preferably a single layer. This makes it possible to further simplify the manufacturing process of the food packaging film 100, i.e., the manufacturing process of the food package according to this embodiment.

[0040] In addition, the heat seal layer 103 is preferably formed by biaxially stretching simultaneously with the biaxially stretched film layer 101 in a state before biaxial stretching. This allows the food packaging film 100 to be produced using a laminated film produced by a molding method such as coextrusion molding, i.e., by one molding operation, and therefore the manufacturing process of the food packaging film 100, i.e., the manufacturing process of the food package according to this embodiment, can be further simplified. Therefore, the heat seal layer 103 is preferably biaxially stretched.

[0041] (Polyolefin) The heat seal layer 103 according to the present embodiment is made of, for example, a polyolefin-based resin composition containing polyolefin. Examples of the polyolefin constituting the heat seal layer 103 include homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, and octene-1; high-pressure low-density polyethylene; linear low-density polyethylene (LLDPE); high-density polyethylene; polypropylene; propylene-α-olefin random copolymers; ethylene-vinyl acetate copolymers (EVA); and ionomer resins. Among these, the polyolefin constituting the heat seal layer 103 is preferably at least one selected from propylene-α-olefin random copolymers and propylene homopolymers, since this has an excellent balance of adhesion to the biaxially oriented film layer 101, heat sealability, etc.

[0042] The propylene-α-olefin random copolymer according to the present embodiment is a random copolymer of propylene and an α-olefin (however, the α-olefin is excluding propylene), and examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. These copolymers may be used alone or in combination of two or more. Among the propylene / α-olefin random copolymers, propylene / ethylene random copolymers, propylene / ethylene / 1-butene random copolymers, and propylene / 1-butene random copolymers are preferred.

[0043] The melting point of the polyolefin constituting the heat seal layer 103 according to this embodiment is preferably in the range of 90° C. to 170° C., more preferably 95° C. to 165° C., and even more preferably 100° C. to 163° C. When the melting point of the polyolefin is equal to or higher than the lower limit, the stickiness of the surface of the heat seal layer 103 can be suppressed, and the blocking property of the food packaging film 100 can be improved. Furthermore, when the melting point of the polyolefin is equal to or lower than the above upper limit, the heat sealability of the food packaging film 100 can be improved.

[0044] The melt flow rate (MFR) of the polyolefin constituting the heat seal layer 103 according to this embodiment, measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and even more preferably 2 g / 10 min or more, from the viewpoint of fluidity and moldability, and is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, and even more preferably 7 g / 10 min or less, from the viewpoint of further stabilizing moldability.

[0045] The content of polyolefin in the polyolefin resin composition according to this embodiment, i.e., the heat seal layer 103, is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, still more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less, when the entire polyolefin resin composition is taken as 100% by mass. This makes it possible to achieve a better balance between adhesion to the biaxially stretched film layer 101, heat sealability, and the like.

[0046] (Other Ingredients) If necessary, various additives such as heat stabilizers, weather stabilizers, antioxidants, UV absorbers, lubricants, slipping agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers may be added to the polyolefin resin composition constituting the heat seal layer 103 in this embodiment, within a range that does not impair the object of this embodiment.

[0047] Moreover, from the viewpoint of improving the heat sealability of the heat seal layer 103, it is preferable that the heat seal layer 103 does not substantially contain a tackifier. More specifically, the content of the tackifier in the heat seal layer 103 is preferably 0.5% by mass or less, more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and particularly preferably 0% by mass. Here, the tackifier is a resinous substance having the property of imparting adhesiveness, which is generally manufactured and sold as a tackifier. Examples of such tackifiers include chroman-based resins such as chroman-indene resin; phenol-based resins such as phenol-formaldehyde resin and xylene-formaldehyde resin; terpene-based resins such as terpene-phenol resin, terpene resin (α,β-pinene resin), aromatic modified terpene resin, and hydrogenated terpene resin; petroleum-based hydrocarbon resins such as synthetic polyterpene resin, aromatic hydrocarbon resin, aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aliphatic and alicyclic petroleum resin, aliphatic and aromatic petroleum resin, unsaturated hydrocarbon polymer, and hydrocarbon tackifying resin; hydrogenated products of the above petroleum-based hydrocarbon resins (also called hydrogenated petroleum hydrocarbon resin); and rosin-based resins such as pentaerythritol ester of rosin, glycerin ester of rosin, hydrogenated rosin, hydrogenated rosin ester, special rosin ester, and rosin-based tackifier.

[0048] (Method for preparing polyolefin-based resin composition) The propylene polymer composition according to the present embodiment can be prepared by mixing or melt-kneading the components using a dry blend, a tumbler mixer, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder, a heat roll, or the like.

[0049] <Method of manufacturing food packaging film> The food packaging film 100 according to this embodiment can be obtained, for example, by co-extrusion molding the above-mentioned propylene polymer composition for forming the biaxially oriented film layer 101 and the above-mentioned polyolefin resin composition for forming the heat seal layer 103 into a film-like laminate film, and then biaxially stretching the laminate film using a known biaxially oriented film manufacturing method such as a simultaneous biaxial stretching method or a sequential biaxial stretching method. The molding device and molding conditions are not particularly limited, and conventionally known molding devices and molding conditions can be used. As the molding device, a multi-layer T-die extruder or a multi-layer inflation molding machine can be used. As the biaxial stretching conditions, for example, known OPP film manufacturing conditions can be used. More specifically, in the sequential biaxial stretching method, for example, the longitudinal stretching temperature may be 100°C to 145°C, the longitudinal stretching ratio may be in the range of 4.5 to 6 times, the transverse stretching temperature may be 130°C to 190°C, and the transverse stretching ratio may be in the range of 9 to 11 times. The food packaging film 100 according to this embodiment can also be obtained by separately forming the biaxially oriented film layer 101 and the heat seal layer 103, laminating them together, and heat forming them.

[0050] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. EXAMPLES

[0051] The present embodiment will be described in detail below with reference to examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0052] 1. Raw materials The raw materials used in the examples and comparative examples are shown below. (1) Propylene polymer PP1: Propylene homopolymer (MFR: 3g / 10min, melting point: 157℃, manufactured by Prime Polymer Co., Ltd.) PP2: Propylene-ethylene random copolymer (MFR: 6g / 10min, melting point: 109℃, Prime Polymer)

[0053] 2. Measurement and evaluation methods (1) MFR of propylene polymer Measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg.

[0054] (2) Melting point of propylene polymer The temperature of the maximum melting peak in the DSC curve of the propylene polymer obtained by using a differential scanning calorimeter (DSC) was taken as the melting point.

[0055] (3) Water vapor barrier properties The food packaging bags prepared in the Examples and Comparative Examples were stored for 72 hours at 40°C and 90% RH. The weight of the calcium chloride was measured before and after storage, and the difference was used to calculate the water vapor permeability (g / (m 2 -24h) were calculated respectively.

[0056] (4) Pore evaluation, Approximately 5 mL of Ageless Seal Check Spray (red penetrant liquid, manufactured by Mitsubishi Gas Chemical Company, Inc.) was sprayed onto the heat-sealed portion from the inside of the food packaging bags prepared in the Examples and Comparative Examples. The bag was then hung vertically with the heat-sealed portion sprayed with Ageless Seal Check Spray facing downward and left for 0.5 hours. The heat-sealed portion was then observed and evaluated for the presence or absence of pores through which the coloring liquid penetrated by capillary action, the pore diameter, the length of the coloring liquid penetrating the pores, and the number of pores.

[0057] (5) Productivity The productivity of food packaging bags was evaluated according to the following criteria. ○: The range of heat sealing conditions can be broadened (there is no need to increase the heat sealing temperature or pressure to block the pores through which the coloring liquid penetrates due to capillary action) ×: The range of heat sealing conditions cannot be widened (the heat sealing temperature and pressure must be increased to block the pores through which the coloring liquid penetrates due to capillary action)

[0058] [Examples 1 to 12 and Comparative Example 1] PP1 for forming the biaxially stretched film layer (thickness: 27 μm) and PP2 for forming the heat seal layer (thickness: 3 μm) were co-extruded, and then biaxially stretched to produce a food packaging film. The co-extrusion conditions and biaxial stretching conditions are as follows: Multi-layer extrusion molding machine: 60mmφ multi-layer T-die extrusion molding machine (L / D=27, manufactured by Screw Seiki Co., Ltd.) Extrusion temperature setting: 200-250℃, Processing speed: 13.5m / min Longitudinal stretching temperature: 110~120℃ Longitudinal stretch ratio: 5.0 times Lateral stretching temperature: 140~170℃ Lateral stretching ratio: 10.0 times Next, the food packaging film was folded back so that the heat-sealed layer was on the inside, and the two sides were heat-sealed to form a bag. Here, a PET film (thickness 12 μm) with a width of 0.3 mm to 5 mm was sandwiched on one side of the heat-sealed part, and heat-sealed. After removing the PET film, calcium chloride was added as the content. Next, the other side was heat-sealed to form a bag with a surface area of ​​0.01 m. 2 Food packaging bags were produced so that the pore size was 0.3 mm or more and 5.0 mm or less. As a result, food packaging bags of Examples 1 to 12 were obtained, each having a pore size of 0.3 mm or more and 5.0 mm or less. The food packaging bag of Comparative Example 1 was obtained in the same manner as in Examples 1 to 12, except that the PET film was not sandwiched. Here, the pore size was adjusted by adjusting the width of the PET film sandwiched between the heat-sealed portions, and the number of pores was adjusted by adjusting the number of PET films sandwiched between the heat-sealed portions. The heat sealing conditions are as follows. Heat seal temperature: 120℃ Heat seal time: 0.5 seconds Heat seal pressure: 1.0kgf

[0059] [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] The food packages of the examples, in which pores existed in the heat-sealed portions through which the coloring liquid penetrated, had water vapor barrier properties equivalent to those of the comparative food packages, in which no such pores existed. From this, it can be understood that the food packages according to the present embodiment have sufficient water vapor barrier properties. [Explanation of symbols]

[0063] 100 Food packaging film 101 Biaxially oriented film layer 103 Heat seal layer

Claims

1. A food packaging bag used for packaging dried food products and made of a food packaging film, When a coloring liquid is sprayed onto the heat-sealed portion of the aforementioned food packaging bag from the inside of the food packaging bag, the coloring liquid penetrates through the pores by capillary action (excluding cases where the coloring liquid penetrates only partway through the sealed portion). ) exists, The water activity of the aforementioned dried food is 0.05 or more and 0.3 or less. The pore diameter of the aforementioned pore is 0.05 mm or more and 5.0 mm or less. A food packaging bag comprising a biaxially oriented film layer made of a propylene polymer composition containing a propylene polymer, and a heat-seal layer provided on at least one side of the biaxially oriented film layer.

2. In the food packaging bag according to Claim 1, A food packaging bag in which the length of the colored liquid that has penetrated the aforementioned pores is 0.1 mm or more and 50 mm or less.

3. In the food packaging bag according to claim 1 or 2, The heat seal layer is provided so as to be in direct contact with at least one surface of the biaxially oriented film layer. A food packaging bag in which the heat-seal layer is the outermost layer and the thickness of the heat-seal layer is 0.1 μm or more and 10 μm or less.

4. In the food packaging bag according to claim 3, A food packaging bag in which the heat-seal layer is a single layer.

5. In the food packaging bag according to claim 3 or 4, A food packaging bag in which the heat-seal layer is biaxially stretched.

6. A food packaging bag according to any one of claims 3 to 5, A food packaging bag comprising the heat-seal layer, which includes at least one selected from propylene-α-olefin random copolymer and propylene homopolymer.

7. A food packaging bag according to any one of claims 3 to 6, A food packaging bag in which the ratio of the thickness of the biaxially oriented film layer to the total thickness of the food packaging film is 0.50 or more and 0.998 or less.

8. A food packaging bag according to any one of claims 1 to 7, Food packaging bags used as outer packaging bags.

9. A method for manufacturing a food packaging bag used for packaging dried food products and composed of a food packaging film, When a coloring liquid is sprayed from inside the food packaging bag, the coloring liquid penetrates through the pores by capillary action (excluding cases where the coloring liquid penetrates partway through the sealed portion). The process includes forming a heat-sealed portion such that a heat-sealed portion exists. The water activity of the aforementioned dried food is 0.05 or more and 0.3 or less. The pore diameter of the aforementioned pore is 0.05 mm or more and 5.0 mm or less. A method for manufacturing a food packaging bag, comprising: a biaxially oriented film layer composed of a propylene polymer composition containing a propylene polymer; and a heat-seal layer provided on at least one side of the biaxially oriented film layer.

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