Food packaging materials

Abstract

To provide a food packaging material that can continuously exhibit the effect of a freshness-retaining substance.SOLUTION: Food packaging material (10, 20) includes a sheet (12, 22) and a freshness-retaining layer (11, 21) laminated on the sheet and including a freshness-retaining agent (14a, 24a). The freshness-retaining agent includes cyclodextrin and a freshness-retaining substance held by the cyclodextrin. The freshness-retaining layer includes a plurality of freshness-retaining agent aggregates (14, 24) formed of a plurality of freshness-retaining agents aggregated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to food packaging materials. [Background technology]

[0002] Food packaging materials containing freshness-preserving agents for maintaining the freshness of food are known. For example, Patent Document 1 discloses a composition of a freshness-preserving agent (freshness-preserving agent) that maintains the freshness of fresh produce by suppressing the deterioration of fresh produce, and packaging materials using the same. The composition of the freshness-preserving agent contains cyclodextrin, which is either a host that does not encapsulate guest molecules or an inclusion complex that encapsulates guest molecules. Patent Document 1 lists, for example, freshness-preserving substances that are effective in antibacterial and antioxidant properties as guest molecules that are effective in maintaining freshness. Patent Document 2 discloses functional water having antibacterial properties, and Patent Document 3 discloses a drip sheet that absorbs drip from food. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-170368 [Patent Document 2] Patent No. 6708764 [Patent Document 3] Patent No. 6320613 [Overview of the project] [Problems that the invention aims to solve]

[0004] According to Patent Document 1, when forming a packaging material or the like using a composition of a freshness maintaining material, a coating material containing the composition of the freshness maintaining material and a binder resin is applied to a sheet with a predetermined thickness, so that a coating layer can be formed in which cyclodextrin is not buried in the binder resin. That is, it is said that most of the cyclodextrin contained in the coating layer is in a state where it is not buried in the binder resin.

[0005] In that case, when cyclodextrin encapsulates a freshness retaining substance as a guest molecule, it is considered that, similar to cyclodextrin, most of the freshness retaining substances contained in the coating layer are not buried in the binder resin, that is, in a state of being exposed on the surface of the coating layer.

[0006] Here, the effect of the freshness retaining substance is exerted mainly by the freshness retaining substance in contact with the food or the liquid generated from the food, for example, by packaging the food with a packaging material or the like with the surface having the coating layer facing inward. Therefore, as described above, when most of the freshness retaining substances are in a state of being exposed on the surface of the coating layer, when the food is packaged with a packaging material or the like with the surface having the coating layer facing inward, the freshness retaining substances will exert their effects on the food all at once. In other words, when the food is packaged with a packaging material or the like, most of the freshness retaining substances will exert their effects at the initial stage after packaging.

[0007] Therefore, in such a packaging material or the like, while the effect of the freshness retaining substance is enhanced at the initial stage after packaging, there is a risk that the effect will end in a short period of time. If that happens, it becomes difficult to extend the expiration date of the food, and it may become difficult to reduce the amount of food to be discarded. Therefore, there is room for improvement in the food packaging material in terms of the sustainability of the effect of the freshness retaining substance.

[0008] Therefore, an object of the present invention is to provide a food packaging material capable of continuously exerting the effect of a freshness retaining substance.

Means for Solving the Problem

[0009] One aspect of the present invention is a food packaging material comprising a sheet and a freshness-preserving layer laminated on the sheet and containing a freshness-preserving agent, wherein the freshness-preserving agent comprises cyclodextrin and a freshness-preserving substance encapsulated in the cyclodextrin, and the freshness-preserving layer contains a plurality of freshness-preserving agent aggregates formed by the aggregation of a plurality of freshness-preserving agents. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a food packaging material that can sustainably exert the effects of freshness-preserving substances. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing an example of the configuration of a food packaging material according to the embodiment. [Figure 2] This is an electron microscope image showing an example of the surface of the freshness-preserving layer according to the embodiment. [Figure 3] This is an electron microscope image showing an example of the surface of a conventional freshness-preserving layer. [Figure 4] This is a perspective view showing an example of the use of the food packaging material according to the embodiment. [Figure 5] This is a cross-sectional view along the VV line in Figure 4. [Figure 6] This is a partial cross-sectional view showing another example of the configuration of the food packaging material according to the embodiment. [Figure 7] This is a cross-sectional view showing another example of use of the food packaging material according to the embodiment. [Figure 8] This is a partial cross-sectional view showing yet another example of the configuration of the food packaging material according to the embodiment. [Figure 9] This is a cross-sectional view showing another example of the configuration of the food packaging material according to the embodiment. [Modes for carrying out the invention]

[0012] This embodiment relates to the following aspects. [Aspect 1] A food packaging material comprising a sheet and a freshness-preserving layer laminated on the sheet and containing a freshness-preserving agent, wherein the freshness-preserving agent comprises cyclodextrin and a freshness-preserving substance encapsulated in the cyclodextrin, and the freshness-preserving layer contains a plurality of freshness-preserving agent aggregates formed by the aggregation of a plurality of freshness-preserving agents.

[0013] In this food packaging material, the freshness-preserving layer of the sheet contains multiple freshness-preserving agent aggregates (aggregates of freshness-preserving agents) formed by the aggregation (consolidation) of multiple freshness-preserving agents. Therefore, when all or part of food is wrapped in the food packaging material with the side having the freshness-preserving layer in contact with the food, initially, the outer freshness-preserving agent in each freshness-preserving agent aggregate, which is more likely to come into contact with the food or liquids produced from the food, releases freshness-preserving substances, thereby exerting the effect of freshness-preserving substances on the food. Then, as time passes, the inner freshness-preserving agents gradually come into contact with the food or liquids produced from the food and release freshness-preserving substances, thereby exerting a sustained effect of freshness-preserving substances on the food. In other words, in this food packaging material, by integrating the freshness-preserving agents, the freshness-preserving layer can be given the property of sustained release of freshness-preserving substances. This improves the persistence of the effect of freshness-preserving substances in the food packaging material. Consequently, the shelf life of food can be extended, and the amount of food waste can be reduced.

[0014] [Aspect 2] The food packaging material according to embodiment 1, wherein the average length of each of the plurality of freshness-preserving agent aggregates in a plan view is 40 to 300 μm. In this food packaging material, the average length of each freshness-preserving agent aggregate in a plan view is 40-300 μm, which allows for more precise expression of the sustained release of freshness-preserving substances in the freshness-preserving layer. This improves the persistence of the effect of freshness-preserving substances in food packaging materials. If the average length is less than 40 μm, the effect of the freshness-preserving substances is exerted in the initial stages after packaging, making it difficult to sustain that effect. On the other hand, if the average length exceeds 300 μm, the freshness-preserving agent aggregate tends to detach easily from the freshness-preserving layer.

[0015] [Aspect 3] The density in plan view of the plurality of freshness-keeping agent aggregates in the freshness-keeping layer is 4 to 40 pieces / mm 2 The food packaging material according to Embodiment 1 or 2. In this food packaging material, the density in plan view of the plurality of freshness-keeping agent aggregates in the freshness-keeping layer is 4 to 40 pieces / mm 2 Therefore, the sustained release property of the freshness-keeping substance in the freshness-keeping layer can be more accurately exhibited. Thereby, the sustainability of the effect of the freshness-keeping substance in the food packaging material can be improved. When the density is less than 4 / mm 2 it becomes difficult to continuously exhibit the effect of the freshness-keeping substance. On the other hand, when the density exceeds 40 pieces / mm 2 the freshness-keeping agent aggregates tend to be arranged close to each other, and the freshness-keeping agent aggregates tend to detach from the freshness-keeping layer.

[0016] [Embodiment 4] The basis weight of the freshness-keeping agent in the freshness-keeping layer is 0.05 to 1 g / m 2 The food packaging material according to any one of Embodiments 1 to 3. In this food packaging material, the basis weight of the freshness-keeping agent in the freshness-keeping layer is 0.05 to 1 g / m 2 Therefore, the sustained release property of the freshness-keeping substance in the freshness-keeping layer can be more accurately exhibited. Thereby, the sustainability of the effect of the freshness-keeping substance in the food packaging material can be improved. When the basis weight is less than 0.05 g / m 2 it becomes difficult to continuously exhibit the effect of the freshness-keeping substance. On the other hand, when the basis weight exceeds 1 g / m 2 the freshness-keeping agent aggregates tend to be arranged close to each other, and the freshness-keeping agent aggregates tend to detach from the freshness-keeping layer.

[0017] [Embodiment 5] The oxygen permeability of the sheet is 50 ml / (m 2 ·d·MPa) or less. The food packaging material according to any one of Embodiments 1 to 4. In this food packaging material, the oxygen permeability of the sheet on which the freshness-keeping layer is laminated is 50 ml / (m 2Because the pressure is below d·MPa, when food is packaged with the freshness-preserving layer facing inward, oxygen penetration into the food can be suppressed. This suppresses oxidation of food and bacterial growth, and as a result, the duration of the effect of freshness-preserving substances in food packaging materials can be improved.

[0018] [Aspect 6] The food packaging material according to any one of embodiments 1 to 4, wherein the sheet comprises a lower layer having liquid absorbency and an upper layer laminated on at least a portion of the lower layer and having breathability and hydrophobicity, and the freshness-preserving layer is laminated on the upper layer. In this food packaging material, the sheet comprises a lower layer with liquid absorbency and an upper layer with breathability and hydrophobicity, with a freshness-preserving layer laminated on the upper layer. Therefore, when the food packaging material is placed in a container and food is placed on its freshness-preserving layer, liquids released from the food can be absorbed by the lower layer via the upper layer, suppressing moisture in the area where the food and the upper layer are in contact. In addition, freshness-preserving substances can be brought into contact with substances contained in the gas inside the container, either through the breathable upper layer or directly, to produce freshness-preserving effects such as antibacterial and antioxidant properties (indirect effect). Furthermore, freshness-preserving effects such as antibacterial and antioxidant properties can be produced at the contact surface when the food and freshness-preserving substances are in direct contact (direct effect). These synergistic effects can suppress oxidation of food and bacterial growth, improving the persistence of the freshness-preserving effect of the food packaging material.

[0019] [Aspect 7] The food packaging material according to embodiment 6, wherein the upper layer is formed of a film having a plurality of openings. In this food packaging material, the upper layer is formed of a film with multiple openings, making it easy to achieve both breathability and hydrophobicity. Therefore, when the food packaging material is placed in a container and food is placed on top of its freshness-preserving layer, liquids released from the food can easily pass through the upper layer to the lower layer, making them easily absorbed in the lower layer.

[0020] [Aspect 8] The food packaging material according to any one of embodiments 1 to 7, wherein the freshness-preserving substance includes an antibacterial agent. In this food packaging material, the freshness-preserving substance contains an antibacterial agent, which improves the duration of the antibacterial effect in the food packaging material.

[0021] [Aspect 9] The food packaging material according to embodiment 8, wherein the antimicrobial agent comprises at least one agent selected from the group consisting of surfactants, metals, metal compounds, quaternary ammonium salts, halogens, halogen compounds, phenolic compounds, alcohols, biguanides, oxidizing agents, and water from which amino groups have been extracted from amino acids. In this food packaging material, the freshness-preserving substance includes the above-mentioned antibacterial agent, thereby improving the duration of the antibacterial effect in the food packaging material.

[0022] [Aspect 10] The food packaging material according to any one of embodiments 1 to 9, wherein the freshness-preserving substance includes an antioxidant. In this food packaging material, the freshness-preserving substance contains antioxidants, which can improve the duration of the antioxidant effect in the food packaging material.

[0023] [Aspect 11] The food packaging material according to embodiment 10, wherein the antioxidant comprises at least one agent selected from the group consisting of alpha-lipoic acid, coenzyme Q10, curcumin, catechins, herbs, chlorophylls, DHA, EPA, 1-methylcyclopropene, halogen compounds of chlorine, bromine, and iodine, carbon dioxide ethanol, propanol, acetic acid, oxalic acid, citric acid, butyric acid, and isovaleric acid. In this food packaging material, the freshness-preserving substance includes the above-mentioned antioxidant, thus improving the duration of the antioxidant effect in the food packaging material.

[0024] [Aspect 12] The food packaging material according to any one of embodiments 1 to 11, wherein the cyclodextrin comprises at least one agent selected from the group consisting of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, branched β-cyclodextrin, methylated α-cyclodextrin, methylated β-cyclodextrin, methylated γ-cyclodextrin, hydroxypropyl α-cyclodextrin, hydroxypropyl β-cyclodextrin, hydroxypropyl γ-cyclodextrin, monochlorotriazino α-cyclodextrin, monochlorotriazino β-cyclodextrin, monochlorotriazino γ-cyclodextrin, triacetyl α-cyclodextrin, triacetyl β-cyclodextrin, and triacetyl γ-cyclodextrin. Because this food packaging material contains the cyclodextrins mentioned above, it can improve the duration of the freshness-preserving effect in food packaging materials.

[0025] The following describes embodiments of the food packaging material of the present invention.

[0026] (Various definitions) In this specification, unless otherwise specified, the various directions are as follows: "The direction perpendicular to the food packaging material placed on a horizontal surface so that the surface on which food is placed faces upward or downward" is called the "thickness direction." "Any direction in a plane perpendicular to the thickness direction" is called the "planar direction." "Viewing the food packaging material placed on a horizontal surface so that the surface on which food is placed faces upward or downward, from the upper or lower side in a direction perpendicular to the planar direction, in the thickness direction" is simply called the "planar view." Furthermore, "the side proximal to the center of the food packaging material in the planar direction" is called the "inner side in the planar direction." "The side distal to the center of the food packaging material in the planar direction" is called the "outer side in the planar direction." However, the center of the food packaging material refers to the centroid of the external shape of the food packaging material in planar view. Of the two opposing surfaces in the thickness direction of food packaging material, the surface on which the food is placed is called the "inner surface," and the other opposite surface is called the "outer surface." Furthermore, "wrapping" (packaging) a portion of food with food packaging material means "covering" a portion of the food with the food packaging material, and in this case too, the term "wrapping" (packaging) is used. In this case, the entire food is stored in a container, or the portion not covered by the food packaging material is covered by other packaging material. These definitions of terms are also used similarly for the components of food packaging material.

[0027] (First Embodiment) [Food packaging materials] Figure 1 is a perspective view showing an example of the configuration of a food packaging material 10 according to an embodiment, and shows two configuration examples, Figure 1(a) and Figure 1(b). The food packaging material 10 is a packaging material containing a freshness-preserving agent for preserving the freshness of fresh foods such as meat, fish, and fruits and vegetables (hereinafter also simply referred to as "food"). By wrapping (packaging) all or part of the food with the food packaging material 10, contact between the outside air and the food is suppressed, and the deterioration of the food's freshness can be suppressed by allowing the freshness-preserving substance (described later) contained in the freshness-preserving agent to act on the food. The food packaging material 10 comprises a sheet 12 and a freshness-preserving layer 11.

[0028] In the example configuration shown in Figure 1(a), the sheet 12 is a component that holds the freshness-preserving layer 11. There are no particular restrictions on the sheet 12 as long as it can hold the freshness-preserving layer 11, and it can be appropriately selected according to the application of the food packaging material 10. In this embodiment, when wrapping food with the food packaging material 10, a material that is impermeable to gases and liquids is used to suppress contact between the outside air and the food. The sheet 12 may be a single-layer sheet or a multi-layer sheet. In this example configuration, the sheet 12 includes an inner layer 17 made of a heat-sealable material and an outer layer 18 made of a material with low gas permeability.

[0029] The freshness-preserving layer 11 is a layer that can suppress the deterioration of the freshness of food. The freshness-preserving layer 11 is laminated on the sheet 12 (the inner layer 17) and contains a plurality of freshness-preserving agents 14a. The freshness-preserving agent 14a has cyclodextrin (host) and a freshness-preserving substance (guest component) encapsulated in the cyclodextrin, and can exhibit the function of preserving the freshness of food and / or suppressing deterioration. In the present invention, the freshness-preserving layer 11 has a plurality of freshness-preserving agent aggregates 14 (aggregates of freshness-preserving agents) that are formed by the aggregation (consolidation) of a plurality of freshness-preserving agents 14a. That is, the freshness-preserving layer 11 comprises a plurality of freshness-preserving agent aggregates 14. In this example configuration, the freshness-preserving layer 11 further comprises a base material 15 that fixes (holds) the plurality of freshness-preserving agent aggregates 14 to the sheet 12. In this case, the base material 15 can be, for example, a synthetic resin such as an adhesive. Multiple freshness-preserving agent aggregates 14 are dispersed in the substrate 15.

[0030] In this configuration example, the freshness-preserving layer 11 can be formed retrofitted to an existing sheet, for example, by coating it onto the sheet. This makes it easy to form the freshness-preserving layer 11 and broadens the range of applications.

[0031] On the other hand, in the configuration example shown in Figure 1(b), the inner layer 17 of the sheet 12 in the configuration example in Figure 1(a) is also used as the base material 15 of the freshness-preserving layer 11. Here, such an inner layer 17 will be referred to as the base material 15. That is, a base material 15 (17) that combines the original function of the base material 15 and the function of the inner layer 17 is laminated on the sheet 12. Therefore, the base material 15 is made of a heat-sealable material and fixes (holds) multiple freshness-preserving agent aggregates 14 to the sheet 12 (outer layer 18). The multiple freshness-preserving agent aggregates 14 are dispersed in the base material 15.

[0032] In this configuration example, for example, by melt-kneading the freshness-preserving agent 14a into the raw material of the inner layer 17 of the sheet, the freshness-preserving layer 11 having the base material 15 (17) and a plurality of freshness-preserving agent assemblies 14 can be formed simultaneously with the formation of the sheet 12 having the outer layer 18. This reduces the formation process and allows the freshness-preserving agent assemblies 14 to be held more stably on the sheet 12.

[0033] In this embodiment, the shape of the food packaging material 10 in plan view is substantially rectangular, but the present invention is not limited to this example, and any external shape (for example, square, polygon, circle, ellipse) can be adopted depending on the desired usage mode, etc.

[0034] Figure 2 is an electron microscope (SEM) image showing an example of the surface of the freshness-preserving layer 11 of the food packaging material 10 according to the embodiment, viewed from above (magnification: 100x). As shown in Figure 2, in the freshness-preserving layer 11, a large number of freshness-preserving agent aggregates 14 are dispersed within the substrate 15. However, the freshness-preserving agent aggregates (aggregates) 14 refer to aggregates (aggregates) of freshness-preserving agent 14a whose longest part has a length of 40 μm or more when viewed from above.

[0035] On the other hand, Figure 3 is an electron microscope (SEM) image showing an example of the surface of a conventional freshness-preserving layer 111 when viewed from above (magnification: 100x). As shown in Figure 3, in the conventional freshness-preserving layer 111, although a few clumps of freshness-preserving agent 114a ranging from a few μm to 20 μm can be seen within the substrate 115, the majority of the freshness-preserving agent 114a exists as particles so small that they are difficult to detect, without forming clumps or aggregates (aggregates).

[0036] Figure 4 is a perspective view showing an example of use of the food packaging material 10 according to the embodiment, and Figure 5 is a cross-sectional view along the VV line in Figure 4. In this example, the food packaging material 10-1 located below the food 50 and the food packaging material 10-2 located above it are both larger in size than the food 50 in a plan view. The freshness-preserving layer 11 of food packaging material 10-1 and the freshness-preserving layer 11 of food packaging material 10-2 are facing each other, the food 50 is sandwiched between the two food packaging materials 10, and the peripheral portions of the two food packaging materials 10 that face each other around the food 50 are joined at the joint 30. The joint 30 can be formed by heat fusion or adhesive bonding (for example, fusion or bonding of the opposing inner layers 17). In a plan view, it is preferable that the food 50 is positioned so that it does not protrude from the food packaging material 10-1 and the food packaging material 10-2. As a result, the food 50 is wrapped and sealed in the food packaging material 10-1 and the food packaging material 10-2. When sealing, it is preferable that the area inside the food packaging material be subjected to a reduced pressure atmosphere. Within the area surrounded by both food packaging materials 10, the surface of the food 50 is in contact with and covered by the freshness preservation layer 11, and the freshness preservation agent aggregate 14 of the freshness preservation layer 11 is in a state in which it can exert its effect.

[0037] From the viewpoint of making it difficult for outside air (such as reactive oxygen species) to reach the food 50 from the joint between the two food packaging materials 10, the joint 30 preferably surrounds at least 90% of the area around the food 50 in a plan view, more preferably surrounds 95% or more, and even more preferably surrounds it completely.

[0038] From the viewpoint of appropriately exhibiting the effect of the freshness preservation agent aggregate 14, the freshness preservation layer 11 preferably covers and closely adheres to at least 80% of the surface of the opposing food 50 in a plan view, more preferably covers and closely adheres to 90% or more, and even more preferably covers and closely adheres to 100%.

[0039] In such food packaging material 10, the freshness-preserving layer 11 of the sheet 12 contains multiple freshness-preserving agent aggregates 14 (aggregates of freshness-preserving agents) formed by the aggregation (consolidation) of multiple freshness-preserving agents 14a. Therefore, when all or part of the food 50 is wrapped in the food packaging material 10 with the side having the freshness-preserving layer 11 in contact with the food 50, initially, in each freshness-preserving agent aggregate 14, the outer freshness-preserving agent 14a, which is more likely to come into contact with the food 50 or the liquid (drip) generated from the food 50, can release freshness-preserving substances. As a result, each freshness-preserving agent aggregate 14 can exert the effect of freshness-preserving substances on the food 50. Then, as time passes, the inner freshness-preserving agent 14a in each freshness-preserving agent aggregate 14 gradually comes into contact with the food 50 or the liquid (drip) generated from the food 50, and can release freshness-preserving substances. As a result, each freshness-preserving agent aggregate 14 can continuously exert the freshness-preserving effect on the food 50. In other words, in this food packaging material 10, by assembling the freshness-preserving agents 14a, the freshness-preserving layer 11 can be given sustained release properties of the freshness-preserving substance. This improves the duration of the freshness-preserving effect in the food packaging material 10. Therefore, the shelf life of the food 50 can be extended, and the amount of food 50 that is wasted can be reduced.

[0040] In the examples shown in Figures 4 and 5, the food packaging material 10 is placed on both the top and bottom of the food 50. However, depending on the type, shape, and characteristics of the food 50, and the intended use of the food packaging material 10, the food packaging material 10 may be placed on only one of the top or bottom sides, with a sheet without a freshness-preserving layer 11 placed on the other side.

[0041] The various components that make up the food packaging material 10 will be described in more detail below.

[0042] [Sheet] The sheet 12 is a component that holds the freshness-preserving layer 11, and there are no particular restrictions on its material as long as it can hold the freshness-preserving layer 11. In this embodiment, it is preferable that the sheet 12 has airtightness (gas impermeability), heat resistance, light-shielding properties, etc., so as to further suppress the deterioration of the freshness of the food 50. However, the resin film may be a single-layer film or a multi-layer film.

[0043] In this embodiment, the sheet 12 has a two-layer structure consisting of an inner layer 17 and an outer layer 18. The inner layer 17 is mainly made of a heat-sealable resin. Examples of heat-sealable resins include polyethylene (PE) such as linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE), polypropylene (PP), and ethylene vinyl acetate copolymer (EVA). The outer layer 18 is mainly made of a resin that has airtightness and other properties. Examples of airtightness and other properties include polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyester resins such as ethylene-vinyl alcohol copolymer and polyethylene terephthalate (PET), and polyamide resins such as nylon (NY). Each of the inner layer 17 and the outer layer 18 may be a single resin layer or multiple resin layers.

[0044] The oxygen permeability of sheet 12 is 50 ml / (m²). 2 Preferably less than d·MPa, and 30 ml / (m 2 10 ml / (m) is more preferable than d·MPa. 2 A value of less than or equal to d·MPa is even more preferable. This suppresses the intrusion of gases such as oxygen into the food 50 when the food is packaged with the freshness-preserving layer 11 side facing inward. This suppresses oxidation of the food 50 and the growth of bacteria, and as a result, improves the persistence of the freshness-preserving substance's effect in the food packaging material 10. However, the oxygen permeability should be measured using an apparatus conforming to JIS K 7126(B) at a temperature of 23°C and a humidity of 65%RH.

[0045] There are no particular restrictions on the thickness of the sheet 12, but examples include 10 μm to 200 μm. Similarly, there are no particular restrictions on the thickness of each of the inner layer 17 and the outer layer 18, but examples include 5 μm to 100 μm for both. The thickness can be measured using a thickness measuring instrument, FS-60DS (presser foot diameter: 50.5 mm, measuring pressure: 0.3 kPa), manufactured by Daiei Kagaku Seiki Seisakusho. Furthermore, the external shape, various dimensions, basis weight, etc. of the resin layers forming the inner layer 17 and the outer layer 18 are not particularly limited as long as they can be used as food packaging materials, and any external shape, various dimensions, basis weight, etc. can be adopted according to the desired heat-sealability, oxygen permeability, strength, etc.

[0046] [Freshness-preserving layer] The freshness-preserving layer 11 is a layer that can suppress the deterioration of the freshness of food, and comprises a plurality of freshness-preserving agent aggregates 14. In this embodiment, it further comprises a base material 15 that fixes (holds) the plurality of freshness-preserving agent aggregates 14 to the sheet 12.

[0047] The freshness preservative aggregate 14 is formed by the aggregation of multiple freshness preservatives 14a. Each freshness preservative 14a comprises a cyclodextrin (host) and a freshness preservative substance (guest component) encapsulated within the cyclodextrin. The freshness preservative aggregate 14 can exert the function of preserving the freshness of food and / or suppressing its deterioration through the freshness preservative substance (guest component).

[0048] The average length of the freshness-preserving agent aggregate 14 in plan view is preferably 40 to 300 μm, more preferably 50 to 200 μm, and even more preferably 60 to 150 μm. This improves the persistence of the freshness-preserving substance's effect in the food packaging material 11. The persistence of the freshness-preserving substance's effect will be discussed later. If the average length is less than 50 μm, the freshness-preserving substance's effect will be exerted in the initial stages after the food 50 is packaged in the food packaging material 11, making it difficult to sustain that effect. On the other hand, if the average length is greater than 300 μm, the freshness-preserving agent aggregate 14 is more likely to detach from the freshness-preserving layer 11. For example, in Figure 2, the average length of the fiber-preserving agent aggregate 14 is 95 μm.

[0049] The density of the freshness-preserving agent aggregates 14 in the freshness-preserving layer 11 in a plan view is 4 to 40 particles / mm². 2 Preferably, 5 to 30 pieces / mm 2 More preferably, 6-20 pieces / mm 2 This is even more preferable. This will further improve the persistence of the freshness-preserving substance's effect in the food packaging material 11. Density is 4 / mm 2 If the density is less than 40 particles / mm³, the freshness-preserving substance will not be able to exert its effect for an extended period. 2 In the case of excessive freshness, the freshness-preserving agent aggregates 14 tend to be positioned close to each other, making it easier for the freshness-preserving agent aggregates 14 to detach from the freshness-preserving layer 11. For example, in Figure 2, the density of freshness-preserving agent aggregates 14 in the freshness-preserving layer 11 in a plan view is 13.1 particles / mm². 2 That is the case.

[0050] However, the method for measuring the average length and density of the freshness-preserving agent aggregate in the freshness-preserving layer in a plan view is as follows. <Method for measuring the average length and density of a freshness-preserving agent aggregate in a plan view> (1) Cut food packaging material into 1cm x 1cm pieces to use as a sample. (2) Place the sample on the sample stage of the electron microscope (FlexSEM1000, manufactured by Hitachi High-Tech Corporation) with the freshness-preserving layer facing upwards. (3) Take an image of the surface of the sample at a magnification of 100x. (4) In the captured image, determine the number of freshness-preserving agent aggregates present in a predetermined area (e.g., 1.27 mm × 887 μm), and the length of the longest part of each of the freshness-preserving agent aggregates. (5) The lengths of the longest parts in each of the multiple freshness-preserving agent assemblies are summed and divided by the number of multiple freshness-preserving agent assemblies to obtain the average length of the freshness-preserving agent assemblies in the sample in a plan view. On the other hand, the number of multiple freshness-preserving agent assemblies is divided by the area of ​​a predetermined region to obtain the density of the freshness-preserving agent assemblies in the sample in a plan view. (6) Perform steps (1) to (5) above for five samples and calculate the average value to determine the average length and density of the final freshness-preserving agent aggregate in plan view.

[0051] However, there are no particular restrictions on the proportion of freshness preservatives that form freshness preservative aggregates among the freshness preservatives in the freshness preservation layer 11, but it is generally 50 wt% or more, preferably 70 wt% or more, and particularly preferably 90 wt% or more. If it is less than 50 wt%, when the food is packaged, a large amount of the freshness preservative will release its freshness preservative substances in the initial stages, and there is a risk that there will be fewer freshness preservatives that can slowly release their freshness preservative substances.

[0052] The freshness preservative 14a comprises cyclodextrin (host) and a freshness preservative substance (guest component) encapsulated within the cyclodextrin, and can exhibit the function of preserving the freshness of food and / or suppressing its deterioration due to the properties of the freshness preservative substance.

[0053] There are no particular restrictions on the cyclodextrin as long as it can encapsulate freshness-preserving substances, but examples include at least one agent selected from the group consisting of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, branched β-cyclodextrin, methylated α-cyclodextrin, methylated β-cyclodextrin, methylated γ-cyclodextrin, hydroxypropyl α-cyclodextrin, hydroxypropyl β-cyclodextrin, hydroxypropyl γ-cyclodextrin, monochlorotriazino α-cyclodextrin, monochlorotriazino β-cyclodextrin, monochlorotriazino γ-cyclodextrin, triacetyl α-cyclodextrin, triacetyl β-cyclodextrin, and triacetyl γ-cyclodextrin. As a result, the cyclodextrin can appropriately encapsulate freshness-preserving substances, thereby improving the duration of the freshness-preserving effect in the food packaging material 10.

[0054] The freshness preservative 14a may contain an antibacterial agent as a freshness preservative substance. In other words, the guest component encapsulated in the cyclodextrin may have antibacterial properties as a characteristic. As a result, the freshness preservation layer 11 in the food packaging material 10 can exert an antibacterial effect, and the duration of that antibacterial effect can be further improved.

[0055] There are no particular restrictions on the antibacterial agent as long as it can be encapsulated in cyclodextrin, but examples include at least one agent selected from the group consisting of surfactants, metals, metal compounds, quaternary ammonium salts, halogens, halogen compounds, phenolic compounds, alcohols, biguanides, oxidizing agents, amino acids, and water from which amino groups have been extracted from amino acids (hereinafter also simply referred to as "amino water"). As a result, the freshness-preserving layer 11 of the food packaging material 10 can exert an antibacterial effect, and the duration of that antibacterial effect can be further improved. However, amino water is disclosed, for example, in Patent Document 2.

[0056] The freshness preservative may contain an antioxidant as a freshness preservative substance. In other words, the guest component encapsulated in the cyclodextrin may have antioxidant properties as part of its characteristics. As a result, in the food packaging material 10, the freshness preservation layer 11 can exert an antioxidant effect, and the duration of that antioxidant effect can be further improved.

[0057] There are no particular restrictions on the antioxidant as long as it can be encapsulated in cyclodextrin, but examples include at least one agent selected from the group consisting of alpha-lipoic acid, coenzyme Q10, curcumin, catechins, herbs, chlorophyll, DHA, EPA, 1-methylcyclopropene, chlorine, bromine, iodine, halogen compounds, carbon dioxide ethanol, propanol, acetic acid, oxalic acid, citric acid, butyric acid, and isovaleric acid. As a result, the freshness-preserving layer 11 of the food packaging material 10 can exert an antioxidant effect, and the duration of that antioxidant effect can be further improved.

[0058] Furthermore, a single food packaging material 10 may contain two types of freshness-preserving substances: an antibacterial agent and an antioxidant. In this case, the ratio of the antibacterial agent to the antioxidant is arbitrary and can be appropriately selected according to the type and shape of the food being packaged, the purpose of the packaging, etc. For example, if it is necessary to enhance the antibacterial effect while also having an antioxidant effect, the ratio of the antibacterial agent to the antioxidant can be set to 6-8:4-2, and if the opposite is true, the ratio can be set to 4-2:6-8.

[0059] The basis weight of the freshness preservative 14a in the freshness preservation layer 11 is 0.05 to 1 g / m². 2 Preferably, 0.1 to 0.5 g / m² is preferred, more preferably 0.15 to 0.3 g / m². 2 This is even more preferable. This allows for a more precise expression of the sustained release of the freshness-preserving substance in the freshness-preserving layer 11. This improves the persistence of the freshness-preserving effect of the freshness-preserving substance in the food packaging material 10. Basis weight: 0.05 g / m² 2 If the basis weight is less than 1 g / m², the freshness-preserving substance will not be able to exert its effect for an extended period. 2 In the case of the freshness-preserving agent aggregates 14, the freshness-preserving agent aggregates 14 tend to be positioned close together, making it easier for them to detach from the freshness-preserving layer 11.

[0060] The substrate 15 fixes (holds) multiple freshness-preserving agent aggregates 14 onto the sheet 12. In other words, the multiple freshness-preserving agent aggregates 14 are dispersed and arranged within the matrix of the substrate 15. However, it is preferable that the substrate 15 holds the freshness-preserving agent aggregates 14 such that at least a portion of each aggregate is exposed on its surface. This allows the freshness-preserving agent aggregates 14 in the substrate 15 to exert their effects.

[0061] In the example configuration shown in Figure 1(a), the base material 15 is, for example, a layer of hardened adhesive (binder). Examples of adhesives include rubber-based adhesives such as natural rubber, butyl rubber, and polyisoprene; styrene-based elastomer adhesives; ethylene-vinyl acetate copolymer (EVA) adhesives; ethylene-acrylic acid derivative copolymer adhesives; ethylene-acrylic acid copolymer (EAA) adhesives; polyamide adhesives; polyolefin adhesives; polyester adhesives, etc., and acrylic adhesives. These adhesives may be used individually or in combination of two or more. Alternatively, the base material 15 may be formed from the same material as the inner layer 17. In that case, the base material 15 can be more easily bonded to the inner layer 17.

[0062] In the example configuration shown in Figure 1(b), the base material 15 is the same as the inner layer 17 described above, and is mainly made of a heat-sealable resin. The heat-sealable resin is the same as in the case of the inner layer 17 described above.

[0063] There are no particular restrictions on the thickness of the base material 15, but examples include 50 to 500 μm. If the thickness is too thin, the freshness-preserving agent aggregate 14 may fall off, and if the thickness is too thick, the freshness-preserving agent aggregate 14 may not be exposed on the surface. Furthermore, the external shape, various dimensions, basis weight, etc. of the resin layer forming the base material 15 are not particularly limited as long as they can be used for food packaging materials, and any external shape, various dimensions, basis weight, etc. can be adopted according to the desired characteristics (for example, the retention of the freshness-preserving agent aggregate 14).

[0064] [Method for manufacturing food packaging materials] Examples of methods for manufacturing the food packaging material 10 include the following: Film manufacturing methods include inflation lamination, T-die lamination, solution flow lamination, and calendering. Nonwoven fabric manufacturing methods include airlaid nonwoven fabrication, air-through nonwoven fabrication, and point bonding. Paper manufacturing methods include various wet lamination processes. Manufacturing methods for combining multiple types of materials include dry lamination, wet lamination, extrusion, and hot melt lamination.

[0065] (In the case of the configuration example in Figure 1(a)) A powdered freshness preservative containing a predetermined freshness-preserving substance, such as powdered cyclodextrin containing a predetermined antibacterial and antioxidant agent, is prepared. This freshness preservative, along with pure water, a water-soluble adhesive, and alcohol, is mixed in a container and stirred for a predetermined time to form a coating solution in which the freshness preservative is dispersed in an aqueous solution. At this time, the size of the freshness preservative aggregates in the aqueous solution, i.e., the size of the aggregates formed by the aggregation of the freshness preservative, can be controlled by changing the stirring conditions, namely the stirring time and rotation speed. In other words, the size of the freshness preservative aggregates (aggregates) can be made larger or smaller by shortening / lengthening the stirring time and slowing / fastening the rotation speed. The above coating solution is then applied to a sheet using a roller coater. This forms a food packaging material on the sheet having a freshness-preserving layer containing freshness-preserving aggregates (aggregates). If the thickness of the freshness-preserving layer is insufficient, the process of applying the coating solution and drying the coating film is repeated.

[0066] (In the case of the configuration example in Figure 1(b)) A powdered freshness-preserving agent containing a predetermined freshness-preserving substance, such as powdered cyclodextrin containing a predetermined antibacterial agent and antioxidant, is prepared. This freshness-preserving agent is mixed with a thermoplastic resin and melt-kneaded for a predetermined time to form a raw material (pellets) for the freshness-preserving layer. At this time, the size of the freshness-preserving agent aggregates in the thermoplastic resin, i.e., aggregates of the freshness-preserving agent, can be controlled by changing the melt-kneading conditions, namely the melt-kneading time and the rotation speed. In other words, the size of the freshness-preserving agent aggregates (aggregates) can be made larger or smaller by shortening / lengthening the melt-kneading time and slowing / fastening the rotation speed. Next, a food packaging material in which a sheet and a freshness-preserving layer are laminated is formed by co-extrusion lamination using the above-mentioned freshness-preserving layer raw material and sheet raw material. Alternatively, the above-mentioned freshness-preserving layer raw material is applied to a sheet using a roller coater. This forms a food packaging material having a freshness-preserving layer on a sheet.

[0067] Furthermore, the manufacturing method for food packaging materials is not limited to this example, as long as it can achieve the above-described structure of the food packaging material.

[0068] (Second Embodiment) [Food packaging materials] Figure 6 is a partial cross-sectional view showing an example of the configuration of a food packaging material 20 according to an embodiment. The food packaging material 20 is also a packaging material that contains a freshness-preserving agent for maintaining the freshness of food. By wrapping (packaging) all or part of the food with the food packaging material 20, liquids such as drip seeping from the food are absorbed, and the freshness-preserving substance acts on the food, thereby suppressing the deterioration of the food's freshness. The food packaging material 20 comprises a sheet 22 laminated in the thickness direction and a freshness-preserving layer 21.

[0069] Sheet 22 is a component that holds the freshness-preserving layer 21. There are no particular restrictions on the sheet 22 as long as it can hold the freshness-preserving layer 21, and it can be appropriately selected according to the application of the food packaging material 20. In this embodiment, when placed under the food packaging material 20, a material that easily absorbs liquids is used to absorb liquids such as drips seeping from the food. Sheet 22 may be a single layer or a multi-layer sheet. In this example configuration, sheet 22 includes an inner layer 27 (upper layer) made of a material that is permeable and hydrophobic (and therefore liquid-permeable), and an outer layer 28 (lower layer) made of a material that can absorb liquids. The permeability (liquid permeability) of the inner layer 27 (upper layer) can be achieved, for example, by a plurality of pores 29.

[0070] The freshness-preserving layer 21 is a layer capable of suppressing the deterioration of food freshness and comprises freshness-preserving agent aggregates 24 and freshness-preserving agent 24a. In this configuration example, the freshness-preserving layer 21 further comprises a base material 25 that fixes (holds) multiple freshness-preserving agent aggregates 24 to the sheet 22. The freshness-preserving layer 21, freshness-preserving agent aggregates 24, freshness-preserving agent 24a, and base material 25 are the same as the freshness-preserving layer 11, freshness-preserving agent aggregates 14, freshness-preserving agent 14a, and base material 15, respectively, except that they are arranged on the sheet 22.

[0071] In this embodiment, the shape of the food packaging material 20 in plan view can be any external shape (for example, square, rectangle, polygon, circle, or ellipse) depending on the desired usage.

[0072] Figure 7 is a cross-sectional view showing an example of use of the food packaging material 20 according to the embodiment. However, Figure 7 is a cross-sectional view along the VV line in Figure 4 when the food packaging material 20 is used together with the food packaging material 10 in the manner shown in the appearance of Figure 4. In this example of use, the configuration described in Figure 4 is basically used, but furthermore, the food packaging material 20 is arranged between the food 50 and the food packaging material 10-1 so that the freshness-preserving layer 21 is in contact with the food 50. In this case, in a plan view, it is preferable that both the food packaging material 10-1 and the food packaging material 10-2 are larger in size than the food packaging material 20, and the food packaging material 20 is larger in size than the food 50. Furthermore, in a plan view, it is preferable that the food 50 is arranged so as not to protrude from the food packaging material 20, and that the food packaging material 20 is arranged so as not to protrude from the food packaging material 10-1 and the food packaging material 10-2. As a result, the food 50 is wrapped and sealed in food packaging materials 10-1 and 10-2, and is in a state where drip can be absorbed by food packaging material 20. When sealing, it is preferable that the area inside the food packaging material be in a reduced-pressure atmosphere. Inside the food packaging material, the surface of the food 50 is in contact with and covered by the freshness-preserving layers 11 and 21, and the freshness-preserving agent assemblies 14 and 24 of the freshness-preserving layers 11 and 21 are in a state where they can exert their effect, and the sheet 22 is in a state where drip can be absorbed.

[0073] From the viewpoint of appropriately exhibiting the effect of the freshness preservation agent aggregate 24, the freshness preservation layer 21 preferably covers and closely adheres to at least 80% of the surface of the opposing food 50 in a plan view, more preferably covers and closely adheres to 90% or more, and even more preferably covers and closely adheres to 100%.

[0074] In this case, in addition to the effects of the food packaging material 10, the food packaging material 20 includes a sheet 22 comprising an outer layer 28 (lower layer) that is liquid absorbent and an inner layer 27 (upper layer) that is breathable and hydrophobic (and therefore also liquid permeable), with the freshness-preserving layer 21 laminated on the inner layer 27. Therefore, when food is placed on the freshness-preserving layer 21, the liquid generated from the food can be absorbed by the outer layer 28 via the inner layer 27, suppressing moisture in the area where the food 50 and the inner layer 27 are in contact. In addition, direct contact between the food 50 and the freshness-preserving layer 22 can produce freshness-preserving effects such as antibacterial and antioxidant properties at the contact surface. These synergistic effects can suppress oxidation of the food 50 and bacterial growth, improving the persistence of the freshness-preserving effect of the food packaging material 20.

[0075] In the example shown in Figure 7, the food packaging material 20 is placed below the food 50. However, depending on the type, shape, and characteristics of the food 50 and the purpose of use of the food packaging material 20, the food packaging material 20 may be placed above, or it may be placed on both the top and bottom. Furthermore, in the example shown in Figure 7, the entire food 50 is covered with food packaging material 10-1 and food packaging material 10-2. However, depending on the type, shape, and characteristics of the food 50 and the purpose and placement of the food packaging material 20, at least one of them may be a sheet that does not include the freshness-preserving layer 11.

[0076] The various components that make up the food packaging material 20 will be described in more detail below.

[0077] [Sheet] The sheet 22 is a component that holds the freshness-preserving layer 21, and there are no particular restrictions on its material as long as it can hold the freshness-preserving layer 21. In this embodiment, it is preferable that the sheet 22 has absorbency so that it can absorb liquids such as drip seeping from the food 50, and also has breathability (liquid permeability) and hydrophobicity so as to lower the humidity of the surface in contact with the food 50. In the example configuration shown in Figure 6, the sheet 22 has a two-layer structure consisting of an inner layer 27 (upper layer) and an outer layer 28 (lower layer).

[0078] (inner layer) The inner layer 27 is located on the side in contact with the freshness-preserving layer 11 and has permeability (liquid permeability) and hydrophobicity to allow liquids such as drip seeping from the food 50 to pass through, while also keeping the humidity of the surface in contact with the food 50 low. The inner layer 27 has a plurality of holes 29 for transferring liquids such as drip seeping from the food 50 to the outer layer 28. Each of the plurality of holes 29 is formed to penetrate from one surface to the other of the inner layer 27, as shown in Figure 6. The holes 29 function as liquid guides that transfer liquids such as drip supplied to the surface on the freshness-preserving layer 11 side (i.e., the surface on which the food 50 is placed) to the outer layer 28. The inner layer 27 may be a single layer or a laminated sheet of multiple layers.

[0079] Each of the multiple holes 29 has a substantially circular opening shape in plan view, and is formed such that the opening area decreases in the thickness direction towards the outer layer 28. Furthermore, each of the multiple holes 29 is arranged in a staggered pattern in the planar direction, thereby making it less likely for variations in rigidity, air permeability (liquid permeability), etc. to occur in the planar direction of the inner layer 27.

[0080] In the above configuration example, the opening shape of each of the multiple holes 29 in plan view is not limited to the above-described approximately circular shape, but can be any shape, such as an ellipse, a polygon with more than one triangle, or a pattern such as a star or a floral design. Furthermore, the arrangement of the multiple holes 29 in the planar direction is not limited to the above-described staggered pattern, but can be any arrangement, such as a grid-like arrangement or an arrangement in the shape of predetermined letters or patterns.

[0081] Furthermore, the number density of the multiple holes 29 formed in the inner layer 27 is not particularly limited, and in the planar direction, for example, it can be 200 holes / cm². 2 ~400 pieces / cm 2 Preferably 250 pieces / cm 2 ~350 pieces / cm 2 , more preferably 270 pieces / cm 2 ~330 pieces / cm 2 It can be formed with a number density of 200 particles / cm³. 2 ~400 pieces / cm2 Within this range, the rigidity of the inner layer 27 is maintained while liquids such as drip seeping from the food 50 can more easily migrate to the outer layer 28, minimizing contact between the food 50 and the drip, and making it easier to maintain the freshness of the food 50.

[0082] Examples of the inner layer 27 include a thermoplastic resin film, and the material of the thermoplastic resin film is not particularly limited as long as it is a thermoplastic resin used in food containers, drip sheets, etc. Suitable thermoplastic resins include olefin resins such as polyethylene (PE) and polypropylene (PP); polyester resins such as polyethylene terephthalate (PET); and ethylene-vinyl acetate copolymer. Among these, olefin resins can be suitably used, and polyethylene can be particularly suitably used. The polyethylene that can be used for the inner layer 27 preferably contains high-density polyethylene, and more preferably contains 50 to 100% by mass of high-density polyethylene.

[0083] Furthermore, the basis weight of the inner layer 27 is not particularly limited; for example, 19 g / m² 2 ~34g / m 2 It is within the range, preferably 22 g / m² 2 ~29g / m 2 It is within the range. The basis weight can be measured as follows: First, take 10 samples of 100 mm x 100 mm size, measure the mass of each sample, and then multiply the mass (g) of each sample by the area (m²) of each sample. 2 The basis weight of each sample is calculated by dividing by ( ). The average basis weight of all 10 samples is calculated and this average value is adopted as the basis weight.

[0084] Furthermore, the thickness of the inner layer 27 is not particularly limited, and is, for example, in the range of 0.10 mm to 0.50 mm, preferably in the range of 0.20 mm to 0.40 mm. The thickness can be measured using a thickness measuring instrument, FS-60DS (presser foot diameter: 50.5 mm, measuring pressure: 0.3 kPa), manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.

[0085] The method for manufacturing the inner layer 27 is not particularly limited. For example, a thermoplastic resin may be melt-kneaded in an extruder, extruded from a T-die, and multiple holes 29 may be formed by suction at multiple locations on a molding drum. Alternatively, a thermoplastic resin film may be formed and then perforated by mechanical means to form multiple holes 29.

[0086] In the food packaging material 20, the inner layer 27 (upper layer) is made of a film having multiple pores 29 (openings), so that both breathability and hydrophobicity can be easily achieved. Therefore, when food 50 is placed on the freshness-preserving layer 11 of the food packaging material 20, liquid generated from the food 50 can easily pass through the inner layer 27 to the outer layer 28, and can be easily absorbed in the lower layer.

[0087] (outer layer) The outer layer 28 is located on the opposite side of the freshness-preserving layer 21, with the inner layer 27 in between, and has absorbent properties to absorb liquids such as drip seeping from the food 50, and can be called an absorbent layer. The outer layer 28 is made of a hydrophilic or hydrophobic nonwoven fabric that can absorb liquids such as drip that have permeated through the inner layer 27 or have migrated from its side.

[0088] The nonwoven fabric forming the outer layer 28 is not particularly limited, and any nonwoven fabric used in drip sheets and the like can be used. Examples of such nonwoven fabrics include those composed of natural fibers or synthetic fibers, and more specifically, those composed of cellulose fibers; thermoplastic resin fibers such as olefin resins and polyester resins. In particular, when the liquid such as drip seeping from food contains a lot of moisture, it is preferable to use a hydrophilic nonwoven fabric such as airlaid pulp, wet crepe paper, tissue paper, or a nonwoven fabric composed of hydrophilically treated synthetic fibers or pulp (e.g., air-through nonwoven fabric). When the liquid such as drip contains a lot of oil, it is preferable to use a hydrophobic nonwoven fabric such as a nonwoven fabric composed of unhydrophilically treated synthetic fibers (e.g., air-through nonwoven fabric).

[0089] Furthermore, when synthetic fibers are used as constituent fibers of the nonwoven fabric forming the outer layer 28, the form of the synthetic fibers is not particularly limited. In addition to the form of ordinary single fibers, core-sheath composite fibers such as PET (core) / PE (sheath), PP (core) / PE (sheath), high-melting-point PP (core) / low-melting-point PP (sheath), high-melting-point PET (core) / low-melting-point PET (sheath) can be used; side-by-side composite fibers; sea-island composite fibers; fibers with irregular cross-sections such as flat, Y-shaped, and C-shaped; and split fibers that are divided by physical loads such as water flow, heat, and embossing can also be used. The above-mentioned fibers that can be used as constituent fibers of the nonwoven fabric may be used individually or in combination of two or more types of fibers. The outer layer 28 may be composed of a single-layer nonwoven fabric or of a multi-layer nonwoven fabric with two or more layers.

[0090] Furthermore, the external shape, various dimensions, and basis weight of the nonwoven fabric forming the outer layer 28 are not particularly limited as long as they can be used for drip sheets, etc., and any external shape, various dimensions, and basis weight can be adopted according to the desired absorbency and strength.

[0091] The overall structure of the food packaging material 20 is not particularly limited. It may have a flat, sheet-like structure, or it may have a predetermined uneven structure that can exhibit liquid diffusion properties (for example, an uneven structure with a corrugated cross-sectional shape or a ridged groove structure). If the bottom of the container body on which the food packaging material 20 is placed has a predetermined uneven structure, the food packaging material 20 may also have an uneven structure that conforms to the uneven structure of the bottom.

[0092] The manufacturing method for the food packaging material 20 having the configuration shown in Figure 6 is the same as the manufacturing method for the configuration example shown in Figure 1(a) of the first embodiment, except that the type of sheet to which the coating liquid is applied is different. A known method for manufacturing drip sheets can be used for manufacturing the sheet.

[0093] Next, other configuration examples of the food packaging material 20 described above will be explained. Note that configurations other than those different from the food packaging material 20 described above are basically the same as those described above, so their explanation will be omitted.

[0094] Figure 8 is a partial cross-sectional view showing another configuration example of the food packaging material 20 according to the embodiment. This food packaging material 20, like the food packaging material 20 shown in Figure 6, comprises a sheet 22 and a freshness-preserving layer 21 laminated in the thickness direction. However, this food packaging material 20 differs from the food packaging material 20 shown in Figure 6 in the configuration of the inner layer 27 (upper layer) in the sheet 22.

[0095] As shown in Figure 8, in this food packaging material 20, each of the multiple holes 29 in the inner layer 27 has a bent portion between the opening on the freshness-preserving layer 21 side and the opening on the outer layer 28 side, such that the inner surface of the opening protrudes toward the center of the hole. That is, each of the multiple holes 29 has a structure in which the opening area gradually decreases from the opening on the freshness-preserving layer 21 side toward the bent portion, the opening area is smallest at the bent portion, and further, the opening area gradually increases from the bent portion toward the opening on the outer layer 28 side.

[0096] If multiple holes 29 have this structure, when a predetermined load is applied to the food packaging material 20 in the thickness direction, the bent portion of the hole 29 can bend and deform to come into contact with the outer layer 28. As a result, liquid such as drip accumulated in the portion between the opening on the freshness-preserving layer 21 side of the hole 29 and the bent portion can be easily transferred to the outer layer 28. Therefore, the humidity on the surface of the sheet 22 can be reduced, and the deterioration of food freshness can be suppressed.

[0097] Furthermore, the specific structure and materials of the food packaging material 20 described above are the same as those of the drip sheet disclosed in Patent Document 3, except for the configuration of the freshness-preserving layer 21.

[0098] Furthermore, the method for manufacturing the food packaging material 20 having the configuration shown in Figure 8 is the same as the method for manufacturing the configuration example shown in Figure 1(a) of the first embodiment, except that the type of sheet to which the coating liquid is applied is different. For the method of manufacturing the sheet, the method for manufacturing a drip sheet disclosed in Patent Document 3 can be used.

[0099] The food packaging material 20 having the configuration shown in Figure 8, like the food packaging material 20 having the configuration shown in Figure 6, has an inner layer 27 (upper layer) made of a film with multiple pores 29 (openings), so that it can easily achieve both breathability and hydrophobicity. Therefore, when food 50 is placed on the freshness-preserving layer 11 of the food packaging material 20, liquid generated from the food 50 can easily pass through the inner layer 27 to the outer layer 28, and can be easily absorbed in the lower layer.

[0100] Furthermore, the food packaging material 20 having the configuration shown in Figure 8, like the food packaging material 20 having the configuration shown in Figure 6, can suppress oxidation of the food 50 and the growth of bacteria through the freshness-preserving layer 21, thereby improving the persistence of the freshness-preserving substance's effect in the food packaging material 20.

[0101] Furthermore, in the food packaging material 20 having the configuration of Figure 8 and the food packaging material 20 having the configuration of Figure 6, the freshness-preserving layer 21 may be positioned between the inner layer 27 and the outer layer 28, or it may be positioned on the opposite side of the outer layer 28 from the inner layer 27.

[0102] Furthermore, in the food packaging material 20 having the configuration of Figure 8 and the food packaging material 20 having the configuration of Figure 6, at least one of the inner layer 27 and the outer layer 28 may consist of multiple layers. Alternatively, another inner layer 27 may be positioned on the opposite side of the outer layer 28 from the inner layer 27. In such cases, the freshness-preserving layer 21 may be positioned to be laminated on at least one of the two outermost surfaces of the laminate of the inner layer 27 and the outer layer 28, or it may be positioned between each layer within the laminate.

[0103] Next, other examples of use of the food packaging material 20 shown in Figures 6 and 8 above will be described. Figure 9 is a cross-sectional view showing another example of use of the food packaging material 20 according to the embodiment. In this example, the food packaging material 20 is placed on the bottom of the container 40, and the food 50 is placed on the food packaging material 20. The external shape and structure of the container 40 are not particularly limited as long as they can accommodate the food packaging material 20 and the food 50, and any external shape (for example, a square, polygon, circle, or ellipse in plan view) and structure (for example, a deep structure such as a bucket or box, or a shallow structure such as a dish) can be adopted according to the desired usage. In this embodiment, the container 40 comprises a container body 41 and a wrapping member 42 that covers the container body 41.

[0104] In this food packaging material 20, when the food packaging material 20 is placed inside the container 40 and food 50 is placed on its freshness-preserving layer 21, liquids generated from the food 50 can be absorbed by the outer layer 28 (lower layer) via the inner layer 27 (upper layer), thereby suppressing moisture in the area where the food 50 and the inner layer 27 (upper layer) are in contact. In addition, the freshness-preserving substance of the freshness-preserving layer 21 can come into contact with substances contained in the gas inside the container 40, either through the permeable inner layer 27 (upper layer) or directly, producing freshness-preserving effects such as antibacterial and antioxidant properties (indirect effect). Furthermore, direct contact between the food 50 and the freshness-preserving substance can produce freshness-preserving effects such as antibacterial and antioxidant properties at the contact surface (direct effect). These synergistic effects can suppress oxidation of the food 50 and bacterial growth, improving the persistence of the freshness-preserving effect of the food packaging material 20.

[0105] (Container body) The container body 41 is formed from a resin molded product, but the material used to form the container body 41 is not limited to resin; materials such as pulp and metal, which are used as forming materials for food containers, can also be used.

[0106] When resin is used as the forming material for the container body 41, the type of resin is not particularly limited, and any resin used as a forming material for food containers can be used. Examples of such resins include styrene-based resins such as polystyrene (PS); olefin-based resins such as polyethylene (PE) and polypropylene (PP); vinyl-based resins such as polyvinyl chloride (PVC) and polyvinyl alcohol (PVA); polyester-based resins such as polyethylene terephthalate (PET) and amorphous polyethylene terephthalate (APET); and biodegradable plastics such as polylactic acid (PLA), polybutylene succinate (PBS), and polyethylene succinate (PES). Among these, styrene-based resins or olefin-based resins can be suitably used, and polystyrene or polypropylene can be particularly suitably used. These resins may be used alone or in combination of two or more resins, and may also be used as a resin composition containing additives such as colorants, preservatives, and antibacterial agents, as well as fillers.

[0107] Furthermore, the container body 41 formed from these resins may be either foamed or non-foamed, and can be arbitrarily selected according to the intended use of the food container.

[0108] Furthermore, the means by which the container body is formed using the above-mentioned resin are not particularly limited, and any molding method such as thermoforming methods like vacuum forming or pressure forming, or injection molding can be employed.

[0109] When pulp is used as the forming material for the container body 41, the type of pulp is not particularly limited, and any pulp used as a forming material for paper containers such as pulp molded containers can be used. Examples of such pulp include wood pulp such as hardwood pulp (L material) and softwood pulp (N material); non-wood pulp such as straw pulp and bagasse pulp; and recycled paper pulp such as recycled newspaper and high-quality recycled paper.

[0110] The means of forming the container body using such pulp are not particularly limited, and for example, pulp molding can be employed. When the container body 41 is formed by such pulp molding, it is preferable to cover at least the inner surface of the container body 41 with a synthetic resin layer from the viewpoint of suppressing the intrusion of outside air. The synthetic resin used for this coating is not particularly limited, and examples include acrylic resins, styrene-acrylic resins, ethylene-vinyl acetate resins, polyvinyl alcohol resins, vinylidene chloride resins, wax resins, fluororesins, and silicone resins. These coating resins may be used alone or in combination of two or more resins, and may also be used as a resin composition containing additives such as colorants, preservatives, and antibacterial agents, as well as fillers. The means of covering the surface of the container body 41 with a synthetic resin layer are not particularly limited, and a synthetic resin film may be laminated onto the surface of the container body, or a solution or melt of synthetic resin may be coated onto the surface of the container body.

[0111] When a metal is used as the forming material for the container body 41, the type of metal is not particularly limited, and any metal used as a forming material for food containers can be used. Examples of such metals include aluminum, iron, stainless steel, copper, and alloys thereof.

[0112] The means by which the container body is formed using such metal are not particularly limited, and any molding method such as press forming or die casting can be employed.

[0113] Furthermore, the material used to form the container body 41 can be a combination of multiple types of materials such as the aforementioned resin, pulp, and metal. For example, the container body 41 can also be formed by press molding using a composite sheet in which a metal layer (for example, a metal foil such as aluminum foil) is laminated on at least one surface of a resin sheet, a composite sheet in which a resin layer is laminated on at least one surface of a metal layer, or a composite sheet in which a resin layer is laminated on at least one surface of a pulp sheet.

[0114] (Wrapping material) The wrapping material 42 is a packaging material used to seal the container body 41 after the food packaging material 20 and food 50 have been placed inside the container body 41.

[0115] Examples of wrapping members 42 include plastic wrap and sealing films. Other options for wrapping members 42 include sealing films (for example, MAP packaging films) that are joined to the flange portion of the container body 41 to seal the internal space of the container body 41, and lid-like members (for example, internal fitting lids, external fitting lids, screw lids, etc.) that engage with the flange portion of the food container to seal the internal space of the food container.

[0116] Furthermore, when wrapping the wrapping member 42 with plastic wrap (i.e., when using plastic wrap film as the wrapping material), the plastic wrap film does not need to cover the entire container body 41, as long as it can seal the internal space of the food container. [Examples]

[0117] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. (1)Food packaging materials (i) Food packaging material shown in Figure 1(b) The food packaging material shown in Figure 1(b) was manufactured by the following method. Powdered β-cyclodextrin containing amino water molecules was mixed with LLDPE and melt-kneaded for a predetermined time to form freshness-preserving layer pellets. Then, the freshness-preserving layer pellets and nylon (NY) pellets were co-extruded to form nylon (15 μm). t ) and LLDPE (30 μm) containing β-cyclodextrin t A food packaging material was obtained in which β-cyclodextrin and amino group water were laminated. The basis weight of β-cyclodextrin and amino group water was 0.238 g / m², respectively. 2 , 0.095g / m 2 That was the case. (b) Food packaging material shown in Figure 1(a) The food packaging material shown in Figure 1(a) was manufactured by the following method. Powdered β-cyclodextrin containing iodine (or R-α-lipoic acid), pure water, a water-soluble adhesive, and ethanol were mixed and stirred for a predetermined time to create a coating solution. This coating solution was then applied to nylon (15 μm) using a roller coater. t ) / LLDPE(30μm t The material was applied to a sheet of ) to obtain a food packaging material in which a nylon (NY) / LLDPE sheet and a coating layer containing β-cyclodextrin were laminated. The basis weights of β-cyclodextrin, iodine, and adhesive were 0.238 g / m² each. 2 , 0.095g / m 2 , 0.223g / m 2 Furthermore, when using powdered β-cyclodextrin containing R-α-lipoic acid instead of iodine, the basis weight of the β-cyclodextrin, R-α-lipoic acid, and adhesive is 0.16 g / m² each. 2 , 0.022 g / m 2 0.18g / m 2 That was the case. (h) Food packaging material shown in Figure 8 The food packaging material shown in Figure 8 was manufactured by the following method. A perforated sheet (inner layer) containing 50% by mass each of LDPE and HDPE manufactured by the manufacturing method of Patent Document 3 was laminated with an airlaid nonwoven fabric made of pulp (outer layer). The above coating liquid was applied to the effective sheet using a roller coater to obtain a food packaging material in which absorbent paper (perforated sheet + airlaid nonwoven fabric) and a coating layer containing β-cyclodextrin were laminated. The basis weight of β-cyclodextrin, iodine, and adhesive was 0.238 g / m² each. 2 , 0.095g / m 2 , 0.223g / m 2 That was the case. (2) Examples and Comparative Examples (i) Examples 1-3 Tuna was packaged using a food packaging material having the configuration shown in Figure 1(b), which was manufactured under melt-mixing conditions of 300 rpm for 1 minute, 10 minutes, and 30 minutes, in the manner of use shown in Figure 5. Beta-cyclodextrin containing amino group water was used as a freshness preservative. (b) Example 4 Tuna was packaged using a food packaging material having the configuration shown in Figure 1(b), manufactured under stirring conditions of 300 rpm for 10 minutes, in the manner of use shown in Figure 5. Beta-cyclodextrin containing iodine was used as a freshness preservative. (h) Example 5 Tuna was packaged using a food packaging material having the configuration shown in Figure 1(a), manufactured under stirring conditions of 300 rpm for 10 minutes, and a food packaging material (for absorbent paper) having the configuration shown in Figure 8, manufactured under stirring conditions of 300 rpm for 10 minutes during mixing, in the manner of use shown in Figure 7. Beta-cyclodextrin containing iodine was used as a freshness preservative. (ii) Comparative Example 1 Tuna was packaged using a food packaging material having the configuration shown in Figure 1(b), manufactured under melt-mixing conditions of 300 rpm for 60 minutes, in the manner of use shown in Figure 5. Beta-cyclodextrin containing amino group water was used as a freshness preservative. (e) Examples 6, 7 Tuna was packaged using a food packaging material (absorbent paper) having the configuration shown in Figure 8, manufactured under stirring conditions of 300 rpm for 10 minutes, in the manner of use shown in Figure 9. Beta-cyclodextrin containing R-α-lipoic acid was used as a freshness preservative. However, in Example 7, the freshness preservation layer was formed between the inner and outer layers. (h) Comparative Example 2 Tuna was packaged using a food packaging material (absorbent paper) having the configuration shown in Figure 8, manufactured under stirring conditions of 300 rpm for 60 minutes, in the manner of use shown in Figure 9. Beta-cyclodextrin containing R-α-lipoic acid was used as a freshness preservative. (3) Evaluation of Examples and Comparative Examples For the food packaging materials obtained in Examples 1-5 and Comparative Example 1, the average length and density of the freshness-preserving agent aggregates in a plan view, as well as the freshness k-value, were measured according to the above-described method for measuring the average length and density of the freshness-preserving agent aggregates and the freshness k-value measurement method described below. Based on these measurements, the relationship between the average length and density of the freshness-preserving agent aggregates and the freshness-preserving effect of the food packaging material was evaluated. The evaluation results, along with the composition of the food packaging material, are shown in Tables 1 and 2 below.

[0118] <Method for measuring freshness k-value> (1) As a food sample to be used to measure the freshness k-value, prepare 30g of raw tuna that is as fresh as possible. (2) Packaging 30g of tuna in the food packaging material to be measured, so that the freshness-preserving layer is in contact with the tuna, as shown in Figure 5, Figure 7, or Figure 9. (3) After storing the tuna, packaged in food packaging material, in a refrigerator at 5°C for 10 days (240 hours), the k-value of each sample (tuna) at 0 hours from the start of storage and after 10 days (240 hours) from the start of storage are measured using a freshness k-value measuring device ("Freshness Checker", manufactured by QS-solution) according to the following procedure (i) to (ix), and the change in k-value (240-hour freshness k-value - 0-hour freshness k-value) is calculated. The sample for the 0-hour mark of the storage period will be cut from the same tuna as the sample stored for 240 hours (30g of tuna). (i) Cut the food ingredient (tuna) into pieces of about 200 mg and place them in a test tube. (ii) Add 600 μL of the freshness checker extraction reagent to the test tube. (iii) Cut the ingredients into small pieces with scissors. (iv) Adjust the pH to neutral with potassium hydroxide. (v) Place the electrophoresis solution in the measurement box attached to the freshness k-value measuring device, fix the filter paper for measurement to the frame, and spray the electrophoresis solution over the entire surface of the filter paper. (vi) Place the frame into the measuring box and drop the supernatant liquid after pH adjustment as described in (iv) onto the center of the filter paper. (vii) Place the measurement box into the measuring instrument of the freshness k-value measuring device and perform electrophoresis for 300 seconds. (viii) Remove the filter paper along with the frame and dry it in the dryer. (ix) Place the dried filter paper into the measuring instrument of the freshness k-value measuring device and irradiate it with ultraviolet light. Take a picture of the spot that appears and analyze it using freshness checker analysis software. (4) The change in the above k value (freshness k value at 240 hours - freshness k value at 0 hours) is defined as the "freshness k value," and this freshness k value is evaluated according to the following criteria. Freshness k value of 10% or less: ◎ (Excellent freshness preservation effect) Freshness k value of 11% or higher and 14% or lower: ○ (Good freshness preservation effect) Freshness k value of 15% or higher: × (Poor freshness preservation effect)

[0119] [Table 1]

[0120] In the food packaging materials of Examples 1 to 5, the freshness-preserving agent in the freshness-preserving layer has a predetermined average length (40 to 300 μm) and a predetermined number density (4 to 40 pieces / mm²). 2 The food packaging materials of Examples 1 to 5 had a freshness-preserving agent aggregate equipped with ). It was found that the food packaging materials of Examples 1 to 5 could exhibit an excellent freshness deterioration suppression effect on food after 240 hours (freshness k value: 14 or less). On the other hand, the food packaging material of Comparative Example 1 did not have a freshness-preserving agent aggregate in the freshness-preserving layer. It was found that the food packaging material of Comparative Example 1 could not exhibit a freshness deterioration effect on food after 240 hours (freshness k value: 15 or more).

[0121] [Table 2]

[0122] In the food packaging materials of Examples 6-7, the freshness-preserving agent in the freshness-preserving layer has a predetermined average length (40-300 μm) and a predetermined number density (4-40 particles / mm²). 2The food packaging materials of Examples 6 and 7 had a freshness-preserving agent aggregate equipped with ). It was found that the food packaging materials of Examples 6 and 7 could exhibit an excellent freshness deterioration suppression effect on food after 240 hours (freshness k value: 10 or less). In Example 7, the freshness-preserving layer was located between the inner and outer layers, but even in this case, it was possible to produce freshness-preserving effects such as antibacterial and antioxidant effects by bringing the freshness-preserving substance into contact with substances contained in the gas inside the container, either through the permeable inner layer or directly (indirect effect). On the other hand, in the food packaging material of Comparative Example 2, the freshness-preserving agent in the freshness-preserving layer did not have a freshness-preserving agent aggregate. It was found that the food packaging material of Comparative Example 1 could not exhibit a freshness deterioration effect on food after 240 hours (freshness k value: 15 or more).

[0123] The present invention is not limited to the embodiments described above, and can be appropriately combined, substituted, or modified with other embodiments or known technologies without departing from the purpose and spirit of the present invention. [Explanation of symbols]

[0124] 10,20 Food packaging materials 11,21 Freshness-preserving layer 12,22 seats 14,24 Freshness Preservative Assembly 14a, 24a Freshness preservative

Claims

1. A food packaging material comprising a sheet and a freshness-preserving layer laminated on the sheet and containing a freshness-preserving agent, The freshness preservative comprises cyclodextrin and a freshness preservative substance encapsulated within the cyclodextrin. The freshness-preserving layer contains multiple freshness-preserving agent aggregates formed by the aggregation of multiple freshness-preserving agents, The average length of each of the aforementioned multiple freshness-preserving agent aggregates in a plan view is 40 to 300 μm. Food packaging materials.

2. The density of the multiple freshness-preserving agent aggregates in the freshness-preserving layer, as viewed from the plan, is 4 to 40 particles / mm². ２ That is, The food packaging material according to claim 1.

3. The basis weight of the freshness-preserving agent in the freshness-preserving layer is 0.05 to 1 g / m². ２ That is, Food packaging material according to claim 1 or 2.

4. The oxygen permeability of the aforementioned sheet is 50 ml / (m²). ２ It is less than or equal to d MPa. A food packaging material according to any one of claims 1 to 3.

5. The aforementioned sheet is A lower layer having liquid absorbency, An upper layer, which is laminated on at least a portion of the lower layer and has breathability and hydrophobicity, Includes, The freshness-preserving layer is laminated on the upper layer, A food packaging material according to any one of claims 1 to 3.

6. The upper layer is formed of a film having a plurality of openings. The food packaging material according to claim 5.

7. The aforementioned freshness-preserving substance includes an antibacterial agent. A food packaging material according to any one of claims 1 to 6.

8. The antimicrobial agent comprises at least one agent selected from the group consisting of surfactants, metals, metal compounds, quaternary ammonium salts, halogens, halogen compounds, phenolic compounds, alcohols, biguanides, oxidizing agents, amino acids, and water from which amino groups have been extracted from amino acids. The food packaging material according to claim 7.

9. The aforementioned freshness-preserving substance includes an antioxidant, A food packaging material according to any one of claims 1 to 8.

10. The antioxidant comprises at least one agent selected from the group consisting of alpha-lipoic acid, coenzyme Q10, curcumin, catechins, herbs, chlorophylls, DHA, EPA, 1-methylcyclopropene, chlorine, bromine, iodine, halogen compounds, carbon dioxide ethanol, propanol, acetic acid, oxalic acid, citric acid, butyric acid, and isovaleric acid. The food packaging material according to claim 9.

11. The cyclodextrin comprises at least one agent selected from the group consisting of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, branched β-cyclodextrin, methylated α-cyclodextrin, methylated β-cyclodextrin, methylated γ-cyclodextrin, hydroxypropyl α-cyclodextrin, hydroxypropyl β-cyclodextrin, hydroxypropyl γ-cyclodextrin, monochlorotriazino α-cyclodextrin, monochlorotriazino β-cyclodextrin, monochlorotriazino γ-cyclodextrin, triacetyl α-cyclodextrin, triacetyl β-cyclodextrin, and triacetyl γ-cyclodextrin. A food packaging material according to any one of claims 1 to 10.

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