Food packaging sheets and food packaging packs

Abstract

To provide a food packaging sheet which prevents generation of cracking and pin holes even when frozen and used, and easily keeps a plurality of food packaging packages independent when the food packaging packages are heated and boiled at the same time.SOLUTION: A food packaging sheet (1) used in a food packaging package (100) capable of being heated and boiled includes an outer layer (10) mainly containing a polyethylene-based resin, an inner layer (20) mainly containing a polyethylene-based resin, and an intermediate layer (30) between the outer layer (10) and the inner layer (20). When outer layers (10) of two food packaging sheets (1) are pressure-bonded in hot water at 95°C at a load of 2 kg / 100 cm2 for 10 minutes, dried and cooled to room temperature, and then peeled at speed of 200 mm / min in a direction of 90°, a peel strength is 0.5 N / 15 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a food packaging sheet and a food packaging pack. [Background technology]

[0002] Food packaging packs in which food (e.g., cooked ingredients such as hamburger steaks and side dishes) are packaged in a food packaging sheet are in use. Such food packaging packs may be heat-treated with hot water or steam to sterilize the food after packaging it in the food packaging sheet, or may be heat-treated with hot water to warm the packaged food before eating. Note that food packaging packs may be transported with the contents frozen from the time they are manufactured until they are delivered to the consumer.

[0003] For example, JP 2015-174347 A (Patent Document 1) discloses a food packaging sheet used in a food packaging pack that can be boiled. The food packaging sheet of Patent Document 1 has an outer layer made of polypropylene resin, an intermediate layer made of polyamide resin, and an inner layer made of polyolefin resin. Since the outer layer of this food packaging sheet is made of polypropylene resin, it can be said to have good heat resistance. However, on the other hand, it does not have sufficient cold impact resistance, and cracks and pinholes may occur during frozen transportation. Furthermore, Patent Document 1 does not disclose anything about keeping multiple food packaging packs independent of each other even when boiling multiple food packaging packs at the same time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-174347 A Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable to develop a food packaging sheet that is less likely to crack or develop pinholes even when used after freezing, and that easily keeps multiple food packaging packs separate when boiling multiple food packaging packs at the same time. [Means for solving the problem]

[0006] The food packaging sheet according to the present invention is A food packaging sheet for use in a boilable food packaging pack, comprising: The present invention comprises an outer layer mainly made of a polyethylene-based resin, an inner layer mainly made of a polyethylene-based resin, and an intermediate layer between the outer layer and the inner layer, Using two food packaging sheets, the outer layers of each were placed in hot water at 95°C at 2 kg / 100 cm 2 The tape is then dried and cooled to room temperature, and then peeled off at a 90° angle at a speed of 200 mm / min. The peel strength is 0.5 N / 15 mm or less.

[0007] According to this configuration, since the outer layer is mainly composed of a polyethylene resin, it is possible to improve cold impact resistance, and cracks and pinholes are less likely to occur even when the product is frozen. In addition, two food packaging sheets were used, and the outer layers of each were placed in hot water at 95°C with a pressure of 2 kg / 100 cm. 2 Since the peel strength is 0.5 N / 15 mm or less when the sheet is compressed for 10 minutes under a load of 0.5 N / 15 mm, dried, cooled to room temperature, and then peeled off in a 90° direction at a speed of 200 mm / min, the outer layers are unlikely to fuse together when multiple food packaging packs are simultaneously boiled, and the food packaging packs are easily kept independent from each other. Therefore, a food packaging sheet can be provided that is unlikely to develop cracks or pinholes even when used frozen, and that is easy to keep multiple food packaging packs independent from each other when multiple food packaging packs are simultaneously boiled.

[0008] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited to the preferred embodiments described below.

[0009] In one embodiment, It is preferable that a sheet piece obtained by cutting into a size of 1 cm x 3 cm is used, and after boiling in hot water at 95°C for 10 minutes, the curl height is 10 mm or less.

[0010] According to this configuration, when the food packaging pack is boiled, curling of the food packaging pack can be kept small.

[0011] In one embodiment, The total penetration energy at -20°C, measured in accordance with JIS K 7124-2, is preferably 0.5 J or more.

[0012] According to this configuration, even when the product is used after being frozen, the occurrence of cracks and pinholes can be effectively suppressed.

[0013] In one embodiment, The outer layer has a density of 0.93 g / cm 3 It is preferable that the linear low density polyethylene mentioned above is contained.

[0014] According to this configuration, the linear low density polyethylene has a density of 0.93 g / cm 3 By including the above-mentioned relatively high density material, it is possible to enhance heat resistance while forming the outer layer mainly from a polyethylene-based resin, and thus it is possible to achieve both heat resistance and cold impact resistance.

[0015] In one embodiment, The glass transition point of the polyethylene resin constituting the outer layer is preferably −50° C. or lower.

[0016] According to this configuration, even when the product is used after being frozen, the occurrence of cracks and pinholes can be effectively suppressed.

[0017] In one embodiment, Using two food packaging sheets, the inner layers of each were placed in hot water at 95°C at 2kg / 100cm 2It is preferable that the peel strength when the adhesive is pressed for 10 minutes under a load of 0.5 N / 15 mm, then dried and cooled to room temperature, and then peeled off in a 90° direction at a speed of 200 mm / min.

[0018] According to this configuration, when the food packaging pack is boiled, the inner layers are less likely to melt together, making it easy to open, and the contents can be easily removed.

[0019] In one embodiment, The inner layer preferably has an innermost layer containing a linear low-density polyethylene resin, and a sub-inner layer containing a biomass-derived low-density polyethylene resin and positioned on the intermediate layer side.

[0020] According to this configuration, by forming the innermost layer containing a linear low-density polyethylene resin, good heat sealability can be obtained when used in food packaging packs. Also, by forming a part of the inner layer located on the intermediate layer side as a sub-inner layer containing a biomass-derived low-density polyethylene resin, the environmental load can be reduced.

[0021] In one embodiment, The density of the linear low-density polyethylene resin constituting the innermost layer is 0.93 g / cm 3 More preferably, it is equal to or greater than this.

[0022] According to this configuration, the linear low density polyethylene has a density of 0.93 g / cm 3 By including the above-mentioned relatively high density material, it is possible to enhance heat resistance while forming the innermost layer mainly from a polyethylene-based resin, and thus it is possible to achieve both heat resistance and cold impact resistance.

[0023] The food packaging pack according to the present invention comprises: It is formed using the food packaging sheet described above and can be boiled.

[0024] With this configuration, it is possible to provide a food packaging pack in which cracks and pinholes are less likely to occur in the food packaging sheet even when the food is transported frozen, and which can be easily kept independent of each other even when multiple food products are boiled simultaneously.

[0025] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings. [Brief description of the drawings]

[0026] [Figure 1] Cross-sectional view of a food packaging pack according to an embodiment. [Diagram 2] Cross-sectional view of another embodiment of a food packaging sheet [Diagram 3] Cross-sectional view of another embodiment of a food packaging sheet [Figure 4] Cross-sectional view of another embodiment of a food packaging sheet DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] An embodiment of a food packaging sheet and a food packaging pack will be described with reference to the drawings. The food packaging sheet 1 of this embodiment is used in a food packaging pack 100 that can be boiled. In this embodiment, as shown in Fig. 1, the food packaging pack 100 is formed by sandwiching food 9 between two food packaging sheets 1 and vacuum-packing them. The food 9 used is, for example, a cooked food ingredient such as a hamburger steak or a side dish, which is heated before eating.

[0028] As shown in Fig. 1, the food packaging sheet 1 includes an outer layer 10, an inner layer 20, and an intermediate layer 30 therebetween. The inner layer 20 is a layer that is bonded to each other when two food packaging sheets 1 are bonded together. The outer layer 10 is a layer that is exposed to the outside when two food packaging sheets 1 are bonded together.

[0029] The outer layer 10 is mainly composed of a polyethylene-based resin. Being mainly composed of a polyethylene-based resin means that more than 50% by weight of the constituent resin of the outer layer 10 is a polyethylene-based resin. The type of the polyethylene-based resin is not particularly limited, and for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid copolymer (EMAA), and ionomer (ION) of ethylene-methacrylic acid copolymer (EMAA) can be used. These may be used alone or in combination of two or more. Of these, linear low-density polyethylene (LLDPE) can be preferably used.

[0030] The melt flow rate (MFR) of the polyethylene resin is not particularly limited, but is preferably 0.1 to 10 g / 10 min, and more preferably 0.2 to 5 g / 10 min. The MFR is measured in accordance with JIS K 7210 at a temperature of 190° C. and a load of 2.16 kg.

[0031] The density of the polyethylene resin is not particularly limited, but is, for example, 0.91 to 0.95 g / cm 3 and preferably 0.93 to 0.95 g / cm 3 It is more preferable that the density is 0.93 g / cm 3 The above linear low density polyethylenes can be preferably used. The density is measured by the underwater displacement method according to JIS K 7112.

[0032] The tensile breaking strength of the polyethylene resin is not particularly limited, but is preferably, for example, 10 to 50 MPa, and more preferably, 30 to 40 MPa. The tensile breaking elongation of the polyethylene resin is not particularly limited, but is preferably, for example, 700 to 1000%, and more preferably, 800 to 900%. The tensile breaking strength and tensile breaking elongation are measured in accordance with JIS K 7127.

[0033] The flexural modulus of the polyethylene resin is not particularly limited, but is preferably, for example, 300 to 1000 MPa, and more preferably 600 to 900 MPa. The flexural modulus is measured in accordance with JIS K 6922.

[0034] The hardness of the polyethylene resin is not particularly limited, but is preferably, for example, 40 to 80 HDD, and more preferably 60 to 70 HDD. The hardness is measured in accordance with JIS K 7215.

[0035] The melting point of the polyethylene resin is not particularly limited, but is preferably, for example, 100 to 140° C., and more preferably 120 to 130° C. The melting point is measured in accordance with JIS K 7121.

[0036] The Vicat softening point of the polyethylene resin is not particularly limited, but is preferably, for example, 100 to 150° C., and more preferably 110 to 130° C. The Vicat softening point is measured in accordance with JIS K 7206.

[0037] The glass transition point of the polyethylene resin is not particularly limited, but is preferably, for example, −120 to −50° C., and more preferably −110 to −90° C. The glass transition point is measured in accordance with JIS K 7121.

[0038] The thickness of the outer layer 10 is not particularly limited, but is preferably, for example, 5 to 50% of the total thickness of the food packaging sheet 1, more preferably 10 to 45%, and even more preferably 20 to 40%.

[0039] The inner layer 20 is mainly composed of a polyethylene-based resin. More than 50% by weight of the constituent resin of the inner layer 20 is composed of a polyethylene-based resin. As the polyethylene-based resin constituting the inner layer 20, the resin types exemplified as the polyethylene-based resin constituting the outer layer 10 can be used in the same way. In addition, those having various properties exemplified as the polyethylene-based resin constituting the outer layer 10 can be used in the same way.

[0040] As another example, as shown in Fig. 2, the inner layer 20 may have a two-layer structure having an innermost layer 21 and a sub-inner layer 22 located on the intermediate layer 30 side. In the example of Fig. 2, the food packaging sheet 1 has a four-layer structure overall, including the outer layer 10, the intermediate layer 30, the sub-inner layer 22, and the innermost layer 21. In such a structure, the innermost layer 21 is preferably composed of a linear low-density polyethylene resin. In particular, the innermost layer 21 is preferably composed of a resin having a density of 0.93 g / cm 3 It is particularly preferable that the resin composition contains the linear low-density polyethylene resin.

[0041] In the example of Fig. 2, a layer having a similar configuration to the sub-inner layer 22 may be provided between the outer layer 10 and the intermediate layer 30. In this case, the layer having a similar configuration to the sub-inner layer 22 in the example of Fig. 2, which is located between the outer layer 10 and the intermediate layer 30, can be referred to as a "sub-outer layer."

[0042] The sub-inner layer 22 is preferably configured to include a biomass-derived low-density polyethylene resin. Here, the biomass-derived low-density polyethylene resin means a resin in which biomass-derived ethylene is used as a raw material for obtaining the above-mentioned polyethylene resin, instead of ethylene obtained from fossil fuels. Biomass-derived ethylene can be obtained by fermenting sugar liquid or starch obtained from plants such as sugar cane, corn, and sweet potato with microorganisms such as yeast to produce bioethanol, and then heating the bioethanol in the presence of a catalyst. Commercially available ethylene can also be used as the biomass-derived ethylene. The content of the biomass-derived polyethylene resin in the sub-inner layer 22 is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more.

[0043] The thickness of the inner layer 20 is not particularly limited, and is preferably, for example, 5 to 50%, more preferably 10 to 45%, and even more preferably 20 to 40% of the total thickness of the food packaging sheet 1. When the inner layer 20 has an innermost layer 21 and a sub-inner layer 22 as in the example of Fig. 2, the thickness of the sub-inner layer 22 is preferably, for example, 20 to 80% of the total thickness of the inner layer 20, more preferably 30 to 75%, and even more preferably 40 to 60%.

[0044] The intermediate layer 30 is provided between the outer layer 10 and the inner layer 20, and provides various properties to the food packaging sheet 1. The resin material constituting the intermediate layer 30 is not particularly limited, but it is preferable that the intermediate layer 30 contains at least a polyamide resin in order to increase the mechanical strength. The type of polyamide resin is not particularly limited, and examples that can be used include nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 46, nylon 66, nylon 69, nylon 610, nylon 611, nylon 6T, nylon 6I, nylon MXD6, nylon 6-66, nylon 6-610, nylon 6-611, nylon 6-12, nylon 6-612, nylon 6-6T, nylon 6-6I, nylon 6-66-610, nylon 6-66-12, nylon 6-66-612, nylon 66-6T, nylon 66-6I, nylon 6T-6I, and nylon 66-6T-6I. These may be used alone or in combination of two or more. Among these, nylon 6 and nylon 6-66 are preferably used.

[0045] As another example, as shown in Fig. 3, the intermediate layer 30 may have a two-layer structure having a first intermediate layer 31 and a second intermediate layer 32 that impart different functions to each other. In the example of Fig. 3, the food packaging sheet 1 has a four-layer structure overall, including an outer layer 10, a first intermediate layer 31, a second intermediate layer 32, and an inner layer 20. The first intermediate layer 31 is preferably composed of a polyamide resin, for example, as described above.

[0046] The second intermediate layer 32 is preferably composed of, for example, a saponified ethylene-vinyl acetate copolymer resin (EVOH). By providing such an EVOH layer as the second intermediate layer 32, oxygen barrier properties can be imparted to the food packaging sheet 1. The ethylene content in the EVOH is not particularly limited, but from the viewpoint of film formation stability, it is preferably 32 to 47 mol%, more preferably 38 to 44 mol%. The saponification degree of the EVOH is preferably 90 mol% or more, more preferably 95 mol% or more.

[0047] The thickness of the intermediate layer 30 is not particularly limited, and is preferably, for example, 5 to 50%, more preferably 10 to 45%, and even more preferably 20 to 40% of the total thickness of the food packaging sheet 1. When the intermediate layer 30 has a first intermediate layer 31 and a second intermediate layer 32 as in the example of Fig. 3, the thickness of the first intermediate layer 31 is preferably, for example, 40 to 90%, more preferably 50 to 80%, and even more preferably 60 to 70% of the total thickness of the inner layer 20.

[0048] Furthermore, the food packaging sheet 1 may further include an adhesive layer 40 as shown in Fig. 4, if necessary, in order to increase the interlayer peel strength of each layer. In the example of Fig. 4, the food packaging sheet 1 has an outer layer 10, an intermediate layer 30, a sub-inner layer 22, and an innermost layer 21, and a first adhesive layer 41 is provided between the outer layer 10 and the intermediate layer 30, and a second adhesive layer 42 is provided between the intermediate layer 30 and the sub-inner layer 22, resulting in a six-layer structure as a whole.

[0049] The resin material constituting the adhesive layer 40 is not particularly limited, and examples thereof include olefin-based resins such as polyethylene (PE) and polypropylene (PP), and ethylene-based copolymers such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), and ethylene-based ionomer (ION).

[0050] The thickness of the adhesive layer 40 is not particularly limited, but is preferably, for example, 3 to 15%, and more preferably 5 to 10%, based on the total thickness of the food packaging sheet 1. When the food packaging sheet 1 has multiple adhesive layers 40 (in the illustrated example, a first adhesive layer 41 and a second adhesive layer 42) as in the example of Fig. 4, each of them preferably has the above thickness.

[0051] As an example, in the six-layer food packaging sheet 1 shown in FIG. 4, the ratio of the thickness of each layer based on the total thickness is preferably: Outer layer 10:20~30% First adhesive layer 41: 5~10% Middle class 30: 20-30% Second adhesive layer 42: 5~10% Sub-inner layer 22: 10~20% Innermost layer 21: 10~20% It is.

[0052] The total thickness of the food packaging sheet 1 is not particularly limited, but is preferably, for example, 60 to 250 μm, more preferably 70 to 200 μm, and even more preferably 75 to 150 μm.

[0053] As shown in FIG. 1, the food packaging pack 100 of this embodiment is joined by sandwiching the food 9 between two food packaging sheets 1 and surface sealing the inner layers 20 around the food 9. The food packaging pack 100 may be boiled to sterilize the food 9 to be packaged, and in this case, multiple (many) food packaging packs 100 may be boiled together. In this case, it is preferable that the food packaging packs 100 do not fuse to each other in hot water during boiling and remain independent. In addition, when the food 9 is removed from the food packaging pack 100, it is necessary to peel off the two food packaging sheets 1. In this case, it is preferable that the food packaging pack 100 allows the two food packaging sheets 1 to be easily peeled off and the food 9 to be easily removed.

[0054] From this viewpoint, the food packaging sheet 1 of this embodiment is formed so that the peel strength when two sheets are peeled off under predetermined conditions satisfies the following condition. Here, the two food packaging sheets 1 may be bonded together with their outer layers 10 pressed against each other or with their inner layers 20 pressed against each other.

[0055] The outer layers 10 of two food packaging sheets 1 are placed together in 95°C hot water at a temperature of 2 kg / 100 cm. 2The peel strength (hereinafter referred to as "outer layer peel strength") when the food packaging packs 100 are pressed for 10 minutes under a load of 0.5 N / 15 mm, dried, cooled to room temperature, and then peeled in a 90° direction at a speed of 200 mm / min is 0.5 N / 15 mm or less. By suppressing the outer layer peel strength to 0.5 N / 15 mm or less, even when multiple (many) food packaging packs 100 are boiled together, the food packaging packs 100 do not fuse to each other in hot water. Therefore, the food packaging packs 100 can remain independent in hot water during boiling. The outer layer peel strength is preferably 0.3 N / 15 mm or less, and more preferably 0.1 N / 15 mm or less.

[0056] The inner layers 20 of two food packaging sheets 1 are placed together in 95°C hot water at a temperature of 2 kg / 100 cm. 2 The peel strength (hereinafter referred to as "inner layer peel strength") when the food packaging sheet 1 is pressed for 10 minutes under a load of 0.5 N / 15 mm, dried, cooled to room temperature, and then peeled in a 90° direction at a speed of 200 mm / min is preferably 0.5 N / 15 mm or less. By keeping the inner layer peel strength at 0.5 N / 15 mm or less, the two food packaging sheets 1 can be easily peeled off when removing the food 9 from the food packaging pack 100, and the food 9 can be easily removed. The inner layer peel strength is more preferably 0.3 N / 15 mm or less, and even more preferably 0.1 N / 15 mm or less.

[0057] From another perspective, it is preferable that the curl height (hereinafter simply referred to as "curl height") of a sheet piece obtained by cutting the food packaging sheet 1 to 1 cm x 3 cm and boiling it in hot water at 95°C for 10 minutes is 10 mm or less. By keeping the curl height of the 1 cm x 3 cm sheet piece to 10 mm or less, the curl can be kept small even when the food packaging pack 100 is boiled. The curl height of the 1 cm x 3 cm sheet piece is more preferably 8 mm or less, and even more preferably 6 mm or less.

[0058] In addition, in the food packaging sheet 1 of this embodiment, both the outer layer 10 and the inner layer 20 are mainly made of polyethylene-based resin and have high symmetry in the thickness direction, which also helps to keep curling of the food packaging pack 100 to a minimum.

[0059] From another viewpoint, the total penetration energy of the food packaging sheet 1 at -20°C is preferably 0.5 J or more. When the total penetration energy at -20°C is 0.5 J or more, the impact resistance at low temperatures can be increased, and for example, cracks and pinholes are less likely to occur even when transported frozen. The total penetration energy is measured in accordance with JIS K 7124-2. The total penetration energy at -20°C is more preferably 0.6 J or more, and even more preferably 0.7 J or more.

[0060] The present invention will be described in more detail below with reference to several test examples, although the scope of the present invention is not limited to the specific test examples described below.

[0061] [Test Example 1] A five-layer laminate film having an outer layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and an inner layer was produced. As the material for the outer layer, linear low-density polyethylene (Yumerit 4040F manufactured by Ube Maruzen) was prepared. As the material for the intermediate layer, nylon (Nylon 1024 manufactured by Ube Industries) was prepared. As the material for the inner layer, linear low-density polyethylene (Yumerit 4040F manufactured by Ube Maruzen) was prepared. As the material for the first adhesive layer and the second adhesive layer, a polyolefin adhesive (Admer NF539 manufactured by Mitsui Chemicals) was prepared. Then, the outer layer, the first adhesive layer, the intermediate layer, the second adhesive layer, and the inner layer were co-extruded in the order listed.

[0062] The total thickness of the obtained laminated film was 80 μm. The ratio of the thickness of each layer to the entire laminated film was as follows: outer layer 30%, first adhesive layer 5%, intermediate layer 30%, second adhesive layer 5%, and inner layer 30%.

[0063] [Test Example 2] A six-layer laminated film having an outer layer, a first adhesive layer, an intermediate layer, a second adhesive layer, a sub-inner layer, and an innermost layer was produced. The materials of the outer layer, the intermediate layer, the first adhesive layer, and the second adhesive layer were the same as those in Test Example 1. Low-density polyethylene (SEB853 manufactured by Braskem) was prepared as the material of the sub-inner layer. Linear low-density polyethylene (Yumerit 4040F manufactured by Ube Maruzen) was prepared as the material of the innermost layer. The outer layer, the first adhesive layer, the intermediate layer, the second adhesive layer, the sub-inner layer, and the innermost layer were co-extrusion molded in the order listed.

[0064] The total thickness of the obtained laminated film was 80 μm. The ratio of the thickness of each layer to the entire laminated film was as follows: outer layer 30%, first adhesive layer 5%, intermediate layer 30%, second adhesive layer 5%, sub-inner layer 15%, and innermost layer 15%.

[0065] [Test Example 3] A six-layer laminate film having an outer layer, a first adhesive layer, a first intermediate layer, a second intermediate layer, a second adhesive layer, and an inner layer was produced. As the material for the outer layer, a mixture of two types of linear low-density polyethylene (Umerit 4040F / Umerit 4540F=50 / 50, manufactured by Ube Maruzen) was prepared. As the material for the first intermediate layer, an ethylene-vinyl alcohol copolymer (Eval F171B, manufactured by Kuraray) was prepared. As the material for the second intermediate layer, nylon (Nylon 1024, manufactured by Ube Industries) was prepared. As the material for the inner layer, a mixture of two types of linear low-density polyethylene (Umerit 4040F / Umerit 4540F=50 / 50, manufactured by Ube Maruzen) was prepared. The materials for the first adhesive layer and the second adhesive layer were the same as those in Test Examples 1 and 2. The outer layer, first adhesive layer, first intermediate layer, second intermediate layer, second adhesive layer, sub-inner layer, and innermost layer were then co-extruded in the order listed.

[0066] The total thickness of the obtained laminated film was 80 μm. The ratio of the thickness of each layer to the entire laminated film was as follows: outer layer 30%, first adhesive layer 5%, first intermediate layer 10%, second intermediate layer 20%, second adhesive layer 5%, and inner layer 30%.

[0067] [Test Example 4] A six-layer laminate film having an outermost layer, a sub-outer layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and an inner layer was produced. The intermediate layer, the first adhesive layer, the second adhesive layer, and the inner layer were made of the same materials as in Test Example 1. As the material for the outermost layer, linear low-density polyethylene (Yumerit 4540F manufactured by Ube Maruzen) was prepared. As the material for the sub-outer layer, low-density polyethylene (SEB853 manufactured by Braskem) was prepared. Then, the outermost layer, the sub-outer layer, the first adhesive layer, the intermediate layer, the second adhesive layer, and the inner layer were co-extruded in the order listed.

[0068] The total thickness of the obtained laminated film was 80 μm. The ratio of the thickness of each layer to the entire laminated film was as follows: outermost layer 15%, sub-outer layer 15%, first adhesive layer 5%, intermediate layer 30%, second adhesive layer 5%, and inner layer 30%.

[0069] [Test Example 5] A five-layer laminate film having an outer layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and an inner layer was produced. The constituent materials of the intermediate layer, the first adhesive layer, and the second adhesive layer were the same as those in Test Example 1. As the constituent material of both the outer layer and the inner layer, linear low-density polyethylene (Yumerit 1540F manufactured by Ube Maruzen) was prepared. The outer layer, the first adhesive layer, the intermediate layer, the second adhesive layer, and the inner layer were co-extruded in the order listed.

[0070] The total thickness of the obtained laminated film was 80 μm. The ratio of the thickness of each layer to the entire laminated film was as follows: outer layer 30%, first adhesive layer 5%, intermediate layer 30%, second adhesive layer 5%, and inner layer 30%.

[0071] Using the laminated film of each test example, the peel strength between the outer layers (the outermost layers in Test Example 4), the peel strength between the inner layers (the innermost layers in Test Example 2), the curl height, and the total penetration energy were measured.

[0072] The peel strength between the outer layers is 2kg / 100cm when the outer layers (or the outermost layers) of two laminated films are peeled together in 95℃ hot water. 2The specimen was then dried and cooled to room temperature, after which it was peeled off in a 90° direction at a speed of 200 mm / min and measured.

[0073] The peel strength between the inner layers is 2kg / 100cm when the inner layers (or the innermost layers) of two laminated films are peeled together in 95℃ hot water. 2 The specimen was then dried and cooled to room temperature, after which it was peeled off in a 90° direction at a speed of 200 mm / min and measured.

[0074] The curl height was measured after the laminated film was cut into a sheet piece of 1 cm x 3 cm and the sheet piece was boiled in hot water at 95°C for 10 minutes.

[0075] The total penetration energy was measured at -20°C in accordance with JIS K 7124-2.

[0076] In addition, food packaging packs were prepared using the laminated film of each test example, and after boiling in hot water at 95°C for 10 minutes, the food packaging packs were visually observed for adhesion between each other, adhesion inside the food packaging pack, and curling of the food packaging pack. In addition, the food packaging packs prepared using the laminated film of each test example were frozen, and visually observed for cracks.

[0077] The results are shown in Table 1.

[0078] [Table 1]

[0079] From these results, it was confirmed that in Test Examples 1 to 4, in which the peel strength between the outer layers was 0.5 N / 15 mm or less, the food packaging packs did not fuse together even after boiling. It was also confirmed that in Test Examples 1 to 4, in which the peel strength between the inner layers was 0.5 N / 15 mm or less, the food packaging packs did not fuse together inside even after boiling. It was also confirmed that in Test Examples 1 to 4, in which the food packaging packs did not fuse together or inside each other, the food packaging packs did not curl even after boiling, and did not crack even after freezing.

[0080] Although the food packaging sheet has been described in detail above by showing specific embodiments and test examples, the present invention is not limited thereto. The embodiments disclosed in this specification are illustrative in all respects and can be appropriately modified within the scope of the present disclosure. [Explanation of symbols]

[0081] 1 Food packaging sheet 9 Food 10 outer layer 20 Inner Layer 21 Innermost layer 22 Sub-inner layer 30 Middle Class 31 First middle layer 32 Second middle layer 40 Adhesive layer 41 First adhesive layer 42 Second adhesive layer 100 Food Packaging Packs

Claims

1. A food packaging sheet for use in a food packaging pack capable of boiling a packaged food, comprising: The food packaging sheet has an outer layer mainly made of a polyethylene resin and exposed to the outside when two food packaging sheets are bonded together, an inner layer mainly made of a polyethylene resin and bonded to each other when the two food packaging sheets are bonded together and in contact with the food, and an intermediate layer between the outer layer and the inner layer, The outer layer has a density of 0.93 g / cm ３ The linear low density polyethylene includes The inner layer has a density of 0.93 g / cm ３ The present invention has an innermost layer containing the linear low-density polyethylene and a sub-inner layer containing a biomass-derived low-density polyethylene resin and positioned on the intermediate layer side, the intermediate layer contains a polyamide resin, Two food packaging sheets were used, and the outer layers of each were placed in hot water at 95°C at a pressure of 2 kg / 100 cm. ２ The peel strength when the sheet is pressed for 10 minutes under a load of 0.5 N / 15 mm and then dried and cooled to room temperature and then peeled off in a 90° direction at a speed of 200 mm / min is 0.5 N / 15 mm or less, Two food packaging sheets were used, and the inner layers of each were placed in hot water at 95°C at a pressure of 2 kg / 100 cm. ２ The peel strength when the sheet is pressed for 10 minutes under a load of 0.5 N / 15 mm and then dried and cooled to room temperature and then peeled off in a 90° direction at a speed of 200 mm / min is 0.5 N / 15 mm or less, A food packaging sheet having a total penetration energy of 0.5 J or more at -20°C, measured in accordance with JIS K 7124-2.

2. A food packaging sheet for use in a food packaging pack capable of boiling a packaged food, comprising: The food packaging sheet has an outer layer mainly made of a polyethylene resin and exposed to the outside when two food packaging sheets are bonded together, an inner layer mainly made of a polyethylene resin and bonded to each other when the two food packaging sheets are bonded together and in contact with the food, and an intermediate layer between the outer layer and the inner layer, The outer layer has a density of 0.93 g / cm ３ The present invention has an outermost layer containing the linear low-density polyethylene and a sub-outer layer containing a biomass-derived low-density polyethylene resin and positioned on the intermediate layer side, The inner layer has a density of 0.93 g / cm ３ The linear low density polyethylene includes the intermediate layer contains a polyamide resin, Two food packaging sheets were used, and the outer layers of each were placed in hot water at 95°C at a pressure of 2 kg / 100 cm. ２ The peel strength when the sheet is pressed for 10 minutes under a load of 0.5 N / 15 mm and then dried and cooled to room temperature and then peeled off in a 90° direction at a speed of 200 mm / min is 0.5 N / 15 mm or less, Two food packaging sheets were used, and the inner layers of each were placed in hot water at 95°C at a pressure of 2 kg / 100 cm. ２ The peel strength when the sheet is pressed for 10 minutes under a load of 0.5 N / 15 mm and then dried and cooled to room temperature and then peeled off in a 90° direction at a speed of 200 mm / min is 0.5 N / 15 mm or less, A food packaging sheet having a total penetration energy of 0.5 J or more at -20°C, measured in accordance with JIS K 7124-2.

3. 3. The food packaging sheet according to claim 1, wherein a piece of the sheet cut into a size of 1 cm x 3 cm has a curl height of 10 mm or less after boiling in hot water at 95°C for 10 minutes.

4. 4. The food packaging sheet according to claim 1, wherein the glass transition point of the polyethylene resin constituting the outer layer is −50° C. or lower.

5. A food packaging pack using the food packaging sheet according to any one of claims 1 to 4, The food packaging pack is formed by sandwiching food between the inner layers of two of the food packaging sheets and face-sealing the inner layers around the food, and the food can be boiled.

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