Packaging materials and packages

Abstract

To provide a packaging material which can hold freshness of a non-heat-treated food product such as vegetables and fruits, and eliminates the possibility of ink transfer even when heated by a microwave oven, and a package obtained using the packaging material.SOLUTION: A packaging material 1 includes: a base material film 10 containing biaxially oriented polypropylene; a printing layer 21 formed on the base material film 10; and a transparent resin layer 30 formed on the printing layer 21. The packaging material 1 has a through hole 40 having an average diameter of 8,000 μm or less, has a water vapor permeation amount under an atmosphere at 40°C and 90%RH of 5 g / m2 day or more. The transparent resin layer 30 contains nitrocellulose. A package obtained using the packaging material 1 has a storage space formed by partially bonding base material film 10 each other, and the printing layer 21 is arranged on a side closer to the storage space than the transparent resin layer 30.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a packaging material and a packaging body. [Background technology]

[0002] Various preservation packages are used to contain and preserve objects. For example, when the object to be preserved is a non-heat-treated food such as fruits and vegetables, the package is required to preserve the object while maintaining its freshness. In addition, the packaging material used for the package is formed with a printing layer to display the contents of the package and to improve the design.

[0003] For example, Patent Document 1 discloses a package comprising a cover material, a container formed from a resin sheet or film, and gelatin-containing contents housed in the container, in which the cover material is provided with at least one of a printed layer, a colored layer, and a coating layer containing a nitrocellulose-based resin and an isocyanate-based hardener. Patent Document 2 discloses a method for producing a packaging material having a magnetizable portion provided by a magnetizable ink, the packaging material being a web or sheet of a packaging laminate comprising a base layer of paper or paperboard that is reshaped into a food packaging container through folding and sealing processes.

[0004] Food containers are increasingly being used as so-called microwave-up containers, which are containers that can be placed directly in a microwave oven for heating. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-313938 A [Patent Document 2] JP 2015-214694 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a package formed using a packaging material having a conventional printed layer is placed directly in a microwave oven and heated, the printed layer peels off and is transferred to the bottom of the microwave oven or to a plate, i.e., there is a problem of ink transfer.

[0007] The present invention has been made in consideration of the above circumstances, and has an objective of providing a packaging material that can maintain the freshness of non-heat-processed foods such as fruits and vegetables and that is free of the risk of ink transfer even when heated in a microwave oven, and a package obtained using the packaging material. [Means for solving the problem]

[0008] The inventors have discovered that by forming a transparent resin layer containing nitrocellulose on a printed layer and forming specified through-holes, it is possible to create a packaging material that can maintain the freshness of unheated processed foods such as fruits and vegetables and that is free from the risk of ink transfer even when heated in a microwave oven, and have thus completed the present invention. That is, the present invention provides the following techniques.

[0009] [1] A packaging material comprising a base film containing biaxially oriented polypropylene, a printed layer formed on the base film, and a transparent resin layer formed on the printed layer, The packaging material has through-holes with an average diameter of 8000 μm or less, and has a water vapor transmission rate of 5 g / m under an atmosphere of 40° C. and 90% RH. 2 ·day or more, The packaging material, wherein the transparent resin layer comprises nitrocellulose. [2] The packaging material described in [1], which is a food packaging material. [3] The packaging material described in [2], which is a packaging material for food heated in a microwave oven. [4] A packaging material according to [2] or [3], which is a packaging material for fresh produce. [5] The packaging material described in any one of [1] to [4], wherein the printed layer contains polyurethane. [6] The packaging material according to any one of [1] to [5], wherein the transparent resin layer contains polyurethane. [7] A package obtained using the packaging material described in any one of [1] to [6], wherein a portion of the base film is bonded to another portion to form a storage space, and the printed layer is positioned on the side of the storage space relative to the transparent resin layer. Effect of the Invention

[0010] The present invention can provide a packaging material that can maintain the freshness of non-heat-processed foods such as fruits and vegetables and that is free of ink transfer even when heated in a microwave oven, and a package obtained using the packaging material. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic view of a packaging material 1 according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic view of a packaging material 1A according to another embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing a schematic diagram of a packaging material 1B according to another embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view showing a schematic view of a packaging body 2 according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A packaging material according to an embodiment of the present invention and a package using the same will be described in detail below. Note that the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0013] <<Packaging material>> The packaging material of the present invention is a packaging material comprising a base film containing biaxially oriented polypropylene, a printed layer formed on the base film, and a transparent resin layer formed on the printed layer.

[0014] 1 is a cross-sectional view showing a schematic diagram of a packaging material according to one embodiment of the present invention. The packaging material 1 according to this embodiment includes a base film 10 containing biaxially oriented polypropylene, a printed layer 21 formed on the base film 10, and a transparent resin layer 30 formed on the printed layer 21, and the transparent resin layer 30 contains nitrocellulose.

[0015] The base film 10 contains biaxially oriented polypropylene. By biaxially oriented the base film 10, it is possible to further reduce the oxygen permeation amount of the base film 10. In addition, it is possible to use cheaper materials and to reduce the anisotropy of elongation.

[0016] The proportion of the polypropylene content in the base film 10 relative to the total mass of the base film 10 is preferably 60% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, and may be, for example, 99% by mass or more or 100% by mass. When the proportion is equal to or more than the lower limit, transparency can be ensured.

[0017] The base film 10 provides both the effect of being biaxially stretched and the effect of containing polypropylene.

[0018] The base film 10 may be made of one or more materials, and when it is made of two or more materials, the combination and ratio of these materials can be selected arbitrarily depending on the purpose.

[0019] The constituent material of the base film 10 is not particularly limited in addition to polypropylene, but preferred examples include polyester, polyolefin, polyimide, polyvinyl, etc. The constituent material of the base film 10 may include polyolefins other than polypropylene. The constituent material of the base film 10 may also include synthetic resins other than these.

[0020] The base film 10 may be made of one layer (single layer) or may be made of two or more layers. When the base film 10 is made of multiple layers, these multiple layers may be the same or different, and the combination of these multiple layers is not particularly limited as long as it does not impair the effects of the present invention.

[0021] In this specification, not only in the case of a base film, "multiple layers may be the same or different" means "all layers may be the same, all layers may be different, or only some layers may be the same", and further, "multiple layers are different" means "at least one of the constituent materials and thicknesses of each layer is different from each other".

[0022] The thickness of the base film 10 is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 150 μm, and particularly preferably 15 to 100 μm. When the thickness of the base film 10 is equal to or greater than the lower limit, the strength of the base film is further improved. When the thickness of the base film 10 is equal to or less than the upper limit, flexibility can be ensured. When the base film 10 is made up of multiple layers, the total thickness of these multiple layers should be set to the above-mentioned preferred base film thickness.

[0023] In the packaging material 1 of this embodiment, a printed layer 21 is formed on one surface 10a of the base film 10. Since the packaging material 1 of this embodiment has the printed layer 21 formed thereon, the contents contained in the package formed of the packaging material 1 can be displayed, and the design of the packaging material 1 can be improved.

[0024] The printing layer 21 can be formed on one surface 10a of the base film 10 using a known ink. Examples of the ink include gravure ink containing a solid content including a colorant and a binder, and a solvent. As the colorant, a general-purpose organic pigment or inorganic pigment or dye can be used. Examples of the binder include nitrocellulose, acrylic resin, polyurethane, and polyamide. The solid content concentration relative to the total mass of the ink is preferably 5 to 50 mass%, more preferably 10 to 40 mass%, and even more preferably 15 to 30 mass%. The printing layer 21 preferably contains polyurethane as a binder.

[0025] Examples of the solvent include ester-based solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate, alcohol-based solvents such as methanol, ethanol, isopropanol, normal propanol, and butanol, glycol-based solvents such as propylene glycol monomethyl ether, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and aliphatic solvents such as hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane. These can be used alone or in combination of two or more.

[0026] In the packaging material 1 of the present embodiment, an area 14 is formed on one surface 10a of the base film 10, where the printed layer 21 is not provided. Through the area 14 on the base film 10 where the printed layer 21 is not provided, the contents contained in the package formed of the packaging material 1 can be visually confirmed.

[0027] The printed layer may be made up of one layer (single layer), or may be made up of two or more layers.

[0028] The packaging material 1 of the present embodiment has a transparent resin layer 30 containing nitrocellulose formed on a printed layer 21. This makes it possible to provide a packaging material that is free from ink transfer even when heated in a microwave oven.

[0029] The transparent resin layer 30 can be formed by printing on the print layer 21 using a transparent ink containing nitrocellulose. Examples of the transparent ink containing nitrocellulose include inks containing a solid content containing nitrocellulose and a solvent. The solid content may contain acrylic resin, polyurethane, polyamide, etc., in addition to nitrocellulose. The solid content concentration relative to the total mass of the ink is preferably 5 to 50 mass%, more preferably 10 to 40 mass%, and even more preferably 15 to 30 mass%.

[0030] Examples of the solvent include the above-mentioned ester-based solvents, alcohol-based solvents, glycol-based solvents, ketone-based solvents, aliphatic solvents, etc. These can be used alone or in combination of two or more kinds.

[0031] The packaging material of the present embodiment has the laminated structure as described above, and in addition, has through holes 40 with an average diameter of 8000 μm or less formed therein.

[0032] The shape of the opening of the through hole on the surface of the packaging material and the shape of the opening of the through hole in a cross section perpendicular to the longitudinal direction thereof are not particularly limited, and may be, for example, any of a circle, an ellipse, a polygon such as a triangle or a rectangle, a combination of two or more shapes selected from the group consisting of a circle, an ellipse, and a polygon, etc. However, from the viewpoint of ease of forming the through hole, the shape is preferably a circle. In this specification, unless otherwise specified, the "opening of the through hole" means both the opening of the through hole on the surface of the above-mentioned packaging material and the opening of the through hole in a cross section perpendicular to its longitudinal direction.

[0033] When the shape of the opening of the through hole is other than circular, the diameter of the through hole means the longest length (maximum diameter) among the lengths of the line segments connecting two different points of the opening.

[0034] The average diameter of the through holes is preferably 30 to 8000 μm, more preferably 40 to 800 μm, and particularly preferably 50 to 500 μm. When the average diameter of the through holes is within this range, the concentrations of oxygen, carbon dioxide, and water vapor can be adjusted in a well-balanced manner to a more suitable range when storing a contained item (non-heat-treated food) in the storage space of a package produced using the packaging material. Furthermore, when the average diameter of the through holes is equal to or greater than the lower limit, the production of the packaging material becomes easier.

[0035] The number of the through holes in the packaging material is not particularly limited, but is preferably 10 to 500 holes / m 2 is preferably 10 to 400 pieces / m 2 More preferably, the number of particles is 10 to 300 particles / m 2 More preferably, the number of particles is 10 to 280 particles / m 2 It is particularly preferable that the number of through-holes is within this range. When the contents (non-heat-treated food) are stored in the storage space of a package produced using the packaging material 1, the concentrations of oxygen, carbon dioxide, and water vapor can be adjusted in a balanced manner to more suitable ranges.

[0036] The number of through holes in the packaging material, i.e., the number of through holes per unit area (1 m 2 The number of through holes per sheet of packaging material can be adjusted by adjusting either or both of the area of ​​the packaging material and the number of through holes per sheet of packaging material.

[0037] The area of ​​the packaging material may be appropriately adjusted depending on the application of the packaging material, and is not particularly limited. For example, it may be 0.01 to 1.5 m 2 It is preferable that the thickness is 0.015 to 1.2 m. 2 More preferably, the thickness is 0.02 to 1 m. 2 It is particularly preferable that the thickness is 0.02 to 0.5 m.2 , 0.02~0.3m 2 , and 0.02 to 0.1 m 2 It may be any of the above.

[0038] The number of through holes per packaging material may be one or more, and may be one or more than one, and may be appropriately adjusted depending on the area and use of the packaging material. The number of through holes per packaging material is, for example, preferably 1 to 30, more preferably 1 to 25, and particularly preferably 1 to 20.

[0039] The position of the through hole 40 in the packaging material is not particularly limited. The through hole 40 may be provided at a position penetrating the transparent resin layer 30, the printed layer 21, and the base film 10, or may be provided at a position penetrating only the base film 10. Fig. 1 is a cross-sectional view that shows a schematic diagram of a packaging material 1 in which a through hole 40 is provided at a position penetrating the transparent resin layer 30, the printed layer 21, and the base film 10. Fig. 2 is a cross-sectional view that shows a schematic diagram of a packaging material 1A in which a through hole 40 is provided at a position penetrating only the base film 10.

[0040] The water vapor permeability of the packaging material at 40℃ and 90% RH is 5g / m 2 day or more, 6g / m 2 ·day or more is preferable, and 8g / m 2 ·day or more is preferable, and 10g / m 2 When the water vapor transmission rate of the packaging material is equal to or more than the lower limit, the occurrence of mold on the contents in the storage space of a package produced using the packaging material is significantly suppressed.

[0041] The upper limit of the water vapor transmission rate of the packaging material under an atmosphere of 40°C and 90% RH is not particularly limited. However, in order to enhance the effect of suppressing drying and wilting of the contents (non-heat-treated foods, particularly fruits and vegetables) in the storage space of a package produced using the packaging material, the water vapor transmission rate of the packaging material is preferably 500,000 g / m 2·day or less is preferable, and 5000g / m 2 ·day or less is more preferable, and 50 g / m 2 It is particularly preferable that the temperature is 0.1 -day or less. The water vapor transmission rate of the packaging material is preferably within a range set by any appropriate combination of any of the above-mentioned lower limit and upper limit.

[0042] The water vapor permeability of the packaging material can be adjusted, for example, by adjusting the size or number of the through holes, or the type or thickness of the constituent material of each layer constituting the packaging material.

[0043] The water vapor transmission rate of the packaging material can be measured in accordance with JIS K 7129B.

[0044] The oxygen permeability of the packaging material under an atmosphere of 20° C. and 80% RH is not particularly limited, but is preferably 2.0×10 8 cc / m 2 ·day or less is preferable, and 1.5×10 7 cc / m 2 ·day or less is preferable, and 1.0×10 5 cc / m 2 It is particularly preferable that the oxygen transmission rate of the packaging material is equal to or less than the upper limit value. When the oxygen transmission rate of the packaging material is equal to or less than the upper limit value, the contents, particularly non-heat-treated foods, can be preserved with more preferable quality in the storage space of a package produced using the packaging material. In particular, when the non-heat-treated foods are fruits and vegetables, the fruits and vegetables respire during storage, but by suppressing the increase in oxygen concentration in the storage space, the respiration of the fruits and vegetables can be suppressed, and the consumption of the fruits and vegetables can be suppressed, allowing the fruits and vegetables to be preserved with a higher freshness.

[0045] The lower limit of the oxygen transmission rate of the packaging material under an atmosphere of 20° C. and 80% RH is not particularly limited. However, in terms of preventing oxygen deficiency of the contents (non-heat-treated foods, particularly fruits and vegetables) in the storage space of the packaging body, the oxygen transmission rate of the packaging material is preferably 0.5×10 3 cc / m 2 ·day or more is preferable, and 1.0×103 cc / m 2 ·days or more is preferable. The oxygen transmission rate of the packaging material is preferably within a range set by any suitable combination of any of the above-mentioned lower limit values ​​and upper limit values.

[0046] The oxygen permeability of the packaging material can be adjusted, for example, by adjusting the size or number of the through holes, or the type or thickness of the constituent material of each layer constituting the packaging material.

[0047] The oxygen permeation amount of the packaging material can be measured, for example, by the following method. That is, a package is prepared using packaging material under atmospheric conditions, and after sealing, the atmosphere in the storage space of the package is replaced with nitrogen gas of purity 99.9% or more V (cc). The time elapsed from the completion of the replacement with nitrogen gas is defined as t (h). The oxygen concentration inside the bag at this time is defined as C t After measuring C0, store the package under conditions of 20°C and 80% RH, and at the stage of t≧3, C0 is measured as follows: t was measured and the oxygen permeability F (cc / m 2 Calculate the number of days. The atmosphere in the storage space of the package after sealing can be replaced with nitrogen gas with a purity of 99.9% or more, for example, by using a syringe needle. t A calibration curve is prepared in advance and is used to determine the amount of F = 1.143 × (C t -C0) × V / t (i)

[0048] FIG. 2 is a cross-sectional view that illustrates a packaging material 1A according to another embodiment. 2, 3 and 4, the same components as those shown in the figures already described are given the same reference numerals as in the figures already described, and detailed description thereof will be omitted.

[0049] The packaging material 1A is a packaging material 1 including a base film 10 containing biaxially oriented polypropylene, a printed layer 21 formed on the base film 10, and a transparent resin layer 30 formed on the printed layer 21, the transparent resin layer 30 containing nitrocellulose. In the packaging material 1A, an area 14 where the printed layer 21 is not provided is formed on one surface 10a of the base film 10, and a through hole 40 is formed in the base film 10 in the area 14 where the printed layer 21 is not provided.

[0050] FIG. 3 is a cross-sectional view that illustrates a packaging material 1B according to another embodiment.

[0051] The packaging material 1B includes a base film 10 containing biaxially oriented polypropylene, a printed layer 21 formed on the base film 10, a printed layer 22 formed on the printed layer 21, a printed layer 23 formed on the printed layer 22, and a transparent resin layer 30 formed on the printed layer 23, and the transparent resin layer 30 contains nitrocellulose. The printed layer 21, the printed layer 22, and the printed layer 23 form a printed layer 20 consisting of multiple layers. In the packaging material 1B, an area 14 on one surface 10a of the base film 10 where the printed layer 20 is not provided is formed, and a through hole 40 is formed in the base film 10 in the area 14 where the printed layer 20 is not provided.

[0052] When the printed layer 20 is composed of multiple layers, among the printed layers 21, 22, and 23, the printed layer 21 on the base film 10 side is preferably light in color, specifically, white. Among the multiple printed layers 20, the printed layer 22 and the printed layer 23 on the transparent resin layer 30 side are preferably darker in color than the printed layer 21 on the base film 10 side.

[0053] The packaging material of the present invention can be used as a packaging material for food, and can be particularly suitably used as a packaging material for food to be heated in a microwave oven.

[0054] The packaging material of the present invention is preferably used for packaging non-heat-treated foods. For example, the packaging material of the present invention is preferably used for packaging fresh produce such as vegetables, fruits, and grains.

[0055] <<Packaging>> The packaging body of the present invention is a packaging body obtained using the packaging material of the above-mentioned embodiment, in which parts of the base films are bonded together to form a storage space, and the printing layer is positioned on the side of the storage space rather than the transparent resin layer.

[0056] FIG. 4 is a cross-sectional view that illustrates a package 2 according to one embodiment of the present invention. The packaging body 2 of this embodiment is obtained by using the packaging material 1 shown in Fig. 1. In the packaging body 2, the other surfaces 10b of the base films 10, 10 of a pair of packaging materials 1, 1 opposite to the printed layer 21 are partially bonded to each other to form a storage space S. The printed layer 21 is disposed closer to the storage space S than the transparent resin layer 30. That is, the packaging materials 1, 1 are disposed such that the base films 10, 10 face each other and the transparent resin layer 30 is the outermost layer. In the storage space S of the package 2, a target item to be stored (not shown) is stored. In FIG. 4, the layer configuration of the base film, the print layer, and the transparent resin layer is omitted.

[0057] The packaging body of this embodiment is made of the packaging material of the above-mentioned embodiment, and the transparent resin layer 30 contains nitrocellulose, so that the risk of ink transfer can be eliminated even when heated in a microwave oven. The packaging body of this embodiment has through holes, so that the freshness of non-heat-treated foods such as fruits and vegetables can be maintained. EXAMPLES

[0058] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the following examples.

[0059] <Ink> Transparent ink 1 (nitrocellulose (product code: 1431-5346, Showa Chemical Co., Ltd.) with solvents: 70% by mass of ethyl acetate, 20% by mass of isopropanol, and 10% by mass of propylene glycol monomethyl ether, adjusted so that the solids concentration relative to the total mass of the ink is 15% by mass.) Transparent ink 2 (nitrocellulose (product code: 1431-5346, Showa Chemical Co., Ltd.) and acrylic resin (Mitsubishi Chemical Corporation, "Dianal (registered trademark) GR5679", weight average molecular weight 30000, Tg 40°C), solvent: 70% by mass of ethyl acetate, 20% by mass of isopropanol, 10% by mass of propylene glycol monomethyl ether, prepared so that the solid content concentration relative to the total mass of the ink is 15% by mass (the mass ratio of nitrocellulose and acrylic resin in the solid content is 70:30).) Transparent ink 3 (Polyurethane resin (Yuriano (registered trademark) KL-593, manufactured by Arakawa Chemical Industries Co., Ltd.) with solvents: 70% by mass of ethyl acetate, 20% by mass of isopropanol, and 10% by mass of propylene glycol monomethyl ether, adjusted so that the solid content concentration relative to the total mass of the ink is 15% by mass.)

[0060] Colored ink 1 (Polyurethane resin (Yuliano (registered trademark) KL-593, manufactured by Arakawa Chemical Industries Co., Ltd.) and nitrocellulose (product code: 1431-5346, manufactured by Showa Chemical Industries Co., Ltd.), pigment (carbon black) 43% by mass, solvent: ethyl acetate 70% by mass, isopropanol 30% by mass, prepared so that the solid content concentration relative to the total mass of the ink is 15% by mass (the mass ratio of nitrocellulose and acrylic resin in the solid content is 2:1).) Colored ink 2 (Polyurethane resin (Yuliano (registered trademark) KL-593, manufactured by Arakawa Chemical Industries Co., Ltd.), 43% by mass of pigment (carbon black), solvent: 70% by mass of ethyl acetate, 30% by mass of isopropanol, adjusted so that the solid content concentration relative to the total mass of the ink is 15% by mass.)

[0061] <Production of packaging materials> [Example 1] A biaxially oriented polypropylene film (Futamura Chemical Co., Ltd., AF-642, thickness 25 μm) was applied as a base film with colored ink 1 and dried at 80° C. to form a printed layer. The printed layer was printed using a gravure printing machine.

[0062] Transparent ink 1 was applied onto the printed layer and dried at 80° C. to form a transparent resin layer. The transparent resin layer was printed using a gravure printing machine. Then, by piercing the needles at sites sufficiently far apart from each other, holes with an average diameter of 60 μm were created over a distance of 1 m. 2 Thus, 15 pieces per package were formed to obtain the packaging material of Example 1.

[0063] [Example 2] A packaging material of Example 2 was obtained in the same manner as in Example 1, except that a printed layer was formed using colored ink 2 and a transparent resin layer was formed on the printed layer using transparent ink 1.

[0064] [Example 3] A packaging material of Example 3 was obtained in the same manner as in Example 1, except that a printed layer was formed using colored ink 1 and a transparent resin layer was formed on the printed layer using transparent ink 2.

[0065] [Example 4] A packaging material of Example 4 was obtained in the same manner as in Example 1, except that a printed layer was formed using colored ink 2 and a transparent resin layer was formed on the printed layer using transparent ink 2.

[0066] [Comparative Example 1] A packaging material of Comparative Example 1 was obtained in the same manner as in Example 1, except that a printed layer was formed using Colored Ink 1 and a transparent resin layer was not formed on the printed layer.

[0067] [Comparative Example 2] A packaging material of Comparative Example 2 was obtained in the same manner as in Example 1, except that a printed layer was formed using Colored Ink 2 and no transparent resin layer was formed on the printed layer.

[0068] [Comparative Example 3] A packaging material of Comparative Example 3 was obtained in the same manner as in Example 1, except that a printed layer was formed using colored ink 1 and a transparent resin layer was formed on the printed layer using transparent ink 3.

[0069] [Comparative Example 4] A packaging material of Comparative Example 4 was obtained in the same manner as in Example 1, except that a printed layer was formed using colored ink 2 and a transparent resin layer was formed on the printed layer using transparent ink 3.

[0070] <Measurement of water vapor transmission rate of packaging materials> The packaging material obtained above was measured for water vapor transmission rate (g / m2) under an atmosphere of 40°C and 90% RH in accordance with JIS K 7129B. 2 The results are shown in Tables 1 and 2.

[0071] <Measurement of oxygen transmission rate of packaging materials> The oxygen transmission rate of the packaging material obtained above was measured by the following method. 2 The results, together with the number of through-holes per well, are shown in Tables 1 and 2.

[0072] (I) Bag preparation Under atmospheric conditions, a bag was prepared using the above packaging material by heat sealing and then sealed.

[0073] (II) Filling the bag with nitrogen gas The inside of the bag was degassed until both sides of the bag were stuck together, and then the bag was filled with nitrogen gas of 99.9% purity or higher. Degassing and nitrogen gas injection were performed by piercing the bag with a syringe needle. The amount of nitrogen gas filled, V (cc), was set as large as possible so that the packaging material was not subjected to excessive tension and was left slightly loose, and was measured using the scale on the syringe barrel. When inserting the syringe needle into the bag, double-sided tape was applied to the relevant location on the packaging material, and a polypropylene film adhesive tape (hereinafter abbreviated as "PP tape") was applied on top of this double-sided tape. After the needle was removed, the pinhole was quickly sealed with PP tape. The area of ​​the PP tape was 4.5 cm2. 2When applying the double-sided tape and PP tape, care was taken not to block the through holes in the packaging material with these tapes.

[0074] (III) Initial oxygen concentration measurement When the filling of the nitrogen gas was completed (t=0), 10 cc or less of gas was sampled from inside the bag, and the initial oxygen concentration C0 (%) inside the bag was measured by gas chromatography (TCD). In this specification, the elapsed time from the completion of filling of the nitrogen gas is defined as t (h), and the oxygen concentration inside the bag at this time is defined as "C t The oxygen concentration is expressed as "CO (%)". Because CO is 0.2% or less, it was decided that if it exceeded 0.2%, the above procedure would be repeated. The amount of sampling gas injected when performing gas chromatography was a fixed amount of about 1cc. Furthermore, gas chromatography was performed on more than two levels of standard gas, including cases with oxygen concentrations of approximately 1% and approximately 10%, and a calibration curve was created.

[0075] (IV) Storage of bags The bag after measuring the initial oxygen concentration was stored in a temperature and humidity chamber at 20°C and 80% RH. The bag was left stationary while being careful not to place anything on top of it or to expose it to the wind from the temperature and humidity chamber fan.

[0076] (V) Measurement of oxygen concentration inside the bag during storage and calculation of oxygen transmission rate After 3 hours or more (t≧3) have passed since the completion of nitrogen gas filling (t=0), gas is sampled from inside the bag a total of 3 to 5 times, including two or more times when the oxygen concentration inside the bag is within the range of 1 to 7%, in the same manner as when measuring C0, and the oxygen concentration C t (%) was measured. t and C t If a proportional relationship with a correlation coefficient of 0.98 or more was not established between the test and the oxygen permeability F (g / m 2 ·day) was calculated.

[0077] If the oxygen permeability of the packaging material is too high and the oxygen concentration inside the bag rises too quickly, and the proportional relationship does not hold, a packaging material made of the same material but with a known lower oxygen permeability is attached to a part of the packaging material, and the oxygen concentration inside the improved bag is measured in the same manner as above. In this case, the area of ​​the region where the packaging material with the lower oxygen permeability is attached is subtracted from the surface area of ​​the original bag, and the value obtained by subtracting the above known oxygen permeability from the oxygen permeability of the packaging material in the improved bag is taken as the oxygen permeability of the desired packaging material. F = 1.143 × (C t -C0) × V / t (i)

[0078] [Table 1]

[0079] [Table 2]

[0080] <Creating the packaging> The packaging material of Example 1 was cut to 200 mm x 400 mm, and the transparent resin layer side was placed on the outside and the base film was placed on the side of the storage space, so that the printed layer was placed on the side of the storage space rather than the transparent resin layer. Then, about 100 g of cut king oyster mushrooms were sandwiched between these packaging materials, and the bags were made into a gable bag and sealed. As a result, 18 bags of the packaged body of Example 1 were made, in which the above-mentioned cut king oyster mushrooms were contained and sealed inside the bag made from the packaging material of Example 1. The bag making was performed at room temperature using a vertical pillow packaging machine (Daiken Corporation, vertical pillow automatic packaging machine, DK-4500 type). Similarly, packages were made using the packaging materials of Examples 2 to 4 and Comparative Examples 1 to 4. The packages obtained above were evaluated according to the following criteria.

[0081] <Range up test> The cut king oyster mushrooms contained in the package were spread all over the package so that the entire package would be heated when it was heated up in the microwave. The film was placed with the back adhesive side facing up, so that the surface with the printed layer and transparent resin layer was in good contact with a plate made of tempered glass (borosilicate glass), and heated in a microwave oven under six different conditions: 500W, 1.5 min; 500W, 2.0 min; 500W, 2.5 min; 600W, 1.5 min; 600W, 2.0 min; 600W, 2.5 min. Similarly, the backing is placed on top, and the surface on which the print layer and the transparent resin layer are formed is mica (KAl2(AlSi3)O 10 The plate was placed directly on the bottom of a microwave oven made of (OH)2) so that it was in good contact with the bottom, and heated in the microwave oven under the same six conditions as above. Similarly, the product was placed with the back adhesive facing up, so that the surface with the printed layer and transparent resin layer was in good contact with a porcelain plate, and heated in a microwave oven under the same six conditions as above.

[0082] When reheating in the microwave, moisture from the cut king oyster mushrooms collected at the bottom of the package and appeared to boil. Observation with a thermal camera showed that the surface temperature of the package rose to approximately 100°C (the boiling point of water). The surface temperature of the plate was also approximately 100°C, and the area showing the highest temperature became larger as the power and time increased.

[0083] After the microwave oven was turned off, the presence or absence of ink transfer (i.e., the presence or absence of transfer) of the printed layer onto a tempered glass dish, a mica microwave oven bottom, or a porcelain dish was observed and evaluated. The results are shown in Tables 3 and 4.

[0084] <Freshness retention test> In the same manner as in the above <Preparation of Package>, 18 sealed packages were prepared, each containing about 100 g of cut eringi mushrooms, using the packaging materials of each Example and Comparative Example. After storing the packages at 25°C for one week, the cut eringi mushrooms were subjected to a sensory evaluation (presence or absence of soft rot, condensation, and odor deterioration) according to the following evaluation criteria.

[0085] <Evaluation criteria> 4: No deterioration observed. 3: Slight deterioration is observed, but still merchantable. 2: Obvious deterioration is observed and the product is not suitable for sale, but is still edible. 1: Significant deterioration is observed and the product is not suitable for consumption.

[0086] [Table 3]

[0087] [Table 4]

[0088] In the packages of Comparative Examples 1 and 2, in which no transparent resin layer was formed, there was no ink transfer to a tempered glass dish or the bottom of a mica microwave oven, but ink transfer was observed to a porcelain dish. In the packaging bodies of Comparative Examples 3 and 4 in which a transparent resin layer was formed, there was no ink transfer to the bottom of the mica microwave oven, but ink transfer was observed to a tempered glass plate and a porcelain plate. In contrast, the packages of Examples 1 to 4, which had a transparent resin layer containing nitrocellulose, did not transfer ink to any of the following: a reinforced glass dish, a mica microwave oven bottom, or a porcelain dish. [Industrial Applicability]

[0089] The packaging material of the present invention can be used as a material for packaging bodies, etc., and packaging bodies made using the packaging material of the present invention can be used as packaging containers for packaging foods such as fresh produce that are to be heated in a microwave oven. [Explanation of symbols]

[0090] Reference Signs List 1, 1A, 1B packaging material, 2 packaging body, 10 base film, 10a one side, 10b other side, 14 area, 20 printed layer, 21 printed layer, 22 printed layer, 23 printed layer, 30 transparent resin layer, 40 through hole, S storage space

Claims

1. A packaging material comprising a base film containing biaxially oriented polypropylene, a printed layer formed on the base film, and a transparent resin layer formed on the printed layer, The packaging material has through holes with an average diameter of 8000 μm or less, and has a water vapor transmission rate of 5 g / m under an atmosphere of 40° C. and 90% RH. ２ ・day or more, The packaging material, wherein the transparent resin layer comprises nitrocellulose.

2. 2. The packaging material of claim 1 which is a food packaging material.

3. 3. The packaging material of claim 2 which is a packaging material for microwave cooked foods.

4. 4. The packaging material according to claim 2 or 3, which is a packaging material for fruits and vegetables.

5. The packaging material according to any one of claims 1 to 4, wherein the printed layer comprises polyurethane.

6. The packaging material according to any one of claims 1 to 5, wherein the transparent resin layer comprises polyurethane.

7. A package obtained using the packaging material according to any one of claims 1 to 6, wherein a portion of the base film is bonded to another portion to form a storage space, and the printed layer is positioned on the side of the storage space relative to the transparent resin layer.

Images