Freshness preservation sheets and refrigerators

Abstract

The purpose of the present disclosure is to provide a freshness retaining sheet with which there is little contamination of an object of freshness retaining, which includes a humidity adjusting function, and which can maintain freshness by absorbing and releasing moisture in a chamber.　This freshness retaining sheet is characterized by: comprising a humidity adjusting part containing a humidity adjusting material, and a humidity release controlling part that controls the release of humidity from the humidity adjusting part; and the humidity adjusting part being solid.

Description

[Technical Field]

[0001] This disclosure relates to a freshness-preserving sheet and a refrigerator. This application claims priority to Japanese Patent Application No. 2021-204854, filed on December 17, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Fresh vegetables contain excess moisture, and when placed in a closed space such as a refrigerator (vegetable compartment) or cooler box, condensation occurs due to evaporation from the vegetables and the low temperature inside the compartment. When condensation occurs, it becomes difficult to maintain the quality of the vegetables, and leafy vegetables in particular are prone to spoilage. Therefore, the humidity in the vegetable compartment is adjusted.

[0003] For example, Patent Document 1 discloses a humidity-conditioning sheet having a water-retaining layer sandwiched between two outer layers, one of which is water-permeable and the other is water-impermeable, and the water-retaining layer contains a liquid humidity-conditioning agent, a glycerin aqueous solution having a concentration of 10% by weight or more and less than 80% by weight, at a glycerin content of 5 to 100 g / m 2 The moisture-regulating sheet is disclosed, which has the effect of suppressing condensation without drying out the food. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-5550 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the above-mentioned sheet uses a liquid humidity-conditioning material, there is a risk that the material may leak and adhere to or contaminate food or the inside of a refrigerator. In particular, when glycerin is used as the liquid humidity-conditioning material, glycerin also serves as a nutrient source for mold, making it easier for mold to grow where the material adheres, posing a hygiene issue.

[0006] In view of the above problems, the present disclosure aims to provide a hygienic freshness-keeping sheet that has a humidity-regulating function and does not contaminate food or the inside of a refrigerator. [Means for solving the problem]

[0007] One aspect of the present disclosure is characterized in that it includes a humidity control section including a humidity control material and a moisture release suppressing section that suppresses moisture release from the humidity control section, and the humidity control material is solid.

[0008] In another aspect of the present disclosure, a refrigerator equipped with a freshness-preserving sheet comprises a storage section for storing an object to be kept fresh, and a cooling section for cooling the air within the storage section, and the freshness-preserving sheet is characterized in that the humidity-regulating section is arranged to face the object to be kept fresh. [Effects of the Invention]

[0009] As described above, according to the present disclosure, since the humidity-conditioning material is solid, leakage of the humidity-conditioning material is reduced, and food and the inside of the refrigerator can be kept hygienic. In addition, a freshness-keeping sheet can be provided that has a humidity-conditioning function and can maintain freshness by absorbing or releasing moisture in a closed space. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the freshness-keeping sheet according to the first embodiment in use. [Figure 2] FIG. 2 is a diagram showing the freshness-keeping sheet according to the first embodiment in use. [Figure 3] FIG. 3 is a cross-sectional view of the freshness-keeping sheet according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view schematically showing a humidity conditioner. [Figure 5] FIG. 5 is a cross-sectional view schematically showing a humidity conditioner supported on a support. [Figure 6] FIG. 6 is a diagram showing the freshness-keeping sheet according to the first embodiment. [Figure 7]FIG. 7 is a diagram showing an example of use of the freshness preservation sheet according to the first embodiment, showing a state in which the room is sealed. [Figure 8] FIG. 8 is a diagram showing an example of how the freshness-preserving sheet according to the first embodiment is used, showing a state in which the room is open. [Figure 9] FIG. 9 is a diagram showing an example of use of the freshness preservation sheet according to the first embodiment, showing a state in which the room has been opened and then sealed again. [Figure 10] FIG. 10 shows a sheet that does not include a moisture release suppression section. [Figure 11] FIG. 11 is a diagram showing a sheet that does not have a humidity control section. [Figure 12] FIG. 12 is a cross-sectional view showing a freshness-keeping sheet according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing a freshness-keeping sheet according to a third embodiment. [Figure 14] FIG. 14 is a cross-sectional view showing a freshness-keeping sheet according to the fourth embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing a freshness-keeping sheet according to Example 2. As shown in FIG. [Figure 16] FIG. 16 is a schematic diagram of a refrigerator equipped with a freshness-keeping sheet according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are necessarily essential as means for solving the problems of the present disclosure.

[0012] [First embodiment] 1 and 2 are diagrams showing a freshness-preserving sheet 100 according to the first embodiment in use. The freshness-preserving sheet 100 according to the first embodiment is used in a closed space requiring humidity control, such as a refrigerator vegetable compartment or a cooler box. As shown in FIG. 1, when an object X whose freshness is to be preserved, such as fresh vegetables, is placed in the refrigerator vegetable compartment immediately after the placement, or when a large amount of vegetables are placed, the vegetables contain a lot of moisture, causing a large amount of water vapor Y to be released from the object X, resulting in an excessively humid room. In such cases, the object X, such as vegetables, especially leafy vegetables, are prone to spoilage. Therefore, adjusting the humidity in the room is important for maintaining freshness.

[0013] Therefore, if the freshness-preserving sheet 100 according to the first embodiment is placed and used indoors, it will have a humidity-regulating function, and the freshness-preserving sheet 100 will absorb water vapor Y evaporated from an object X such as vegetables, thereby suppressing condensation in the room and maintaining the freshness of the object X for a longer period of time.

[0014] On the other hand, as shown in Figure 2, when object X, such as vegetables, is kept cold for a long period of time indoors or when the amount of object X decreases, the room will become dry. Also, even when object X, such as vegetables, is kept cold for a short period of time, if the cooling method used in the room is gas compression, gas absorption, electronic, or cold storage, there will be locally low-temperature areas (cooling sections), and when the indoor air is cooled in the cooling section, water vapor will condense and liquefy in the cooling section, causing the absolute humidity in the room to decrease and the room to become dry.

[0015] Therefore, if the freshness-preserving sheet 100 of the first embodiment is placed and used indoors, the freshness-preserving sheet 100 will emit water vapor Y, preventing the room from drying out and allowing the freshness of the object X to be maintained for a longer period of time.

[0016] In other words, by having a humidity-regulating function, freshness preservation sheet 100 can absorb or release water vapor Y in the room, thereby maintaining the freshness of object X, such as vegetables, for a longer period of time. Freshness preservation sheet 100 according to the first embodiment will be described in detail below.

[0017] Fig. 3 is a cross-sectional view of freshness preservation sheet 100 according to the first embodiment. As shown in Fig. 3, freshness preservation sheet 100 according to the first embodiment includes humidity control section 10 including humidity control material 11, and moisture release suppression section 20 that suppresses moisture release from humidity control section 10.

[0018] The humidity control unit 10 and the moisture release suppression unit 20 are layered and stacked, so that the humidity control unit 10 and the moisture release suppression unit 20 are in close contact with each other. The humidity control unit 10 and the moisture release suppression unit 20 are bonded together and integrated. The humidity control unit and the moisture release suppression unit face each other. As shown in FIG. 3 , the humidity control unit 10 absorbs and releases water vapor Y, absorbing and releasing moisture. Meanwhile, the moisture release suppression unit 20 suppresses absorption of water vapor Y from the outside (outside air) of the humidity control unit 10 and suppresses excessive release of water vapor Y from the humidity control unit 10. In particular, at low humidity, there is a possibility that the humidity control unit 10 will release too much water vapor Y, so the moisture release suppression unit 20 suppresses the excessive release of water vapor Y, thereby moisturizing the vegetables.

[0019] The moisture release suppression unit 20 has a lower water vapor permeability than the humidity control unit 10, and suppresses moisture release from the humidity control unit 10 when the interior of the room 30, such as the vegetable compartment, is dry, prioritizing moisture release toward the vegetables. The moisture release suppression unit 20 is made of a film material such as polyethylene, polypropylene, PET, or nylon. The water vapor permeability is approximately 190g / (m 2 ·h) The following materials are preferred:

[0020] The moisture release suppression unit 20 is preferably made of a material whose water vapor permeability changes with humidity. The moisture release suppression unit 20 is preferably made of a material whose water vapor permeability is high at high humidity and low at low humidity. The moisture release suppression unit 20 is made, for example, of an asymmetric polymer film made by bonding a hydrophilic polymer and a hydrophobic polymer. When the humidity level increases, the hydrophilic polymer captures some of the moisture in the atmosphere, creating molecular-level gaps through which humid air can easily move, thereby increasing the water vapor permeability. On the other hand, when the humidity level is low, there are almost no gaps within the hydrophilic polymer through which water vapor can pass, resulting in a high water vapor permeability. By placing the hydrophilic polymer side facing the outside air, the water vapor permeability is low when the outside humidity is low, suppressing moisture release from the humidity control unit and efficiently moisturizing vegetables for a long period of time. Examples of hydrophilic polymers include polyvinyl alcohol, and examples of hydrophobic polymers include polypropylene and polyethylene. Thus, it is preferable that the weight ratio of the hydrophobic polymer is higher on the humidity control unit 10 side.

[0021] The humidity control unit 10 includes a humidity control material 11 that absorbs moisture when the humidity is high and releases moisture when the humidity is low. In other words, the humidity control material 11 adjusts the amount of water vapor Y contained in the air. The humidity control material 11 also has the property of absorbing moisture when the surrounding humidity is relatively high compared to the equilibrium humidity, and conversely, releasing moisture when the surroundings become dry. Unlike desiccants such as silica gel and zeolite, it repeatedly absorbs and releases moisture, so in principle it is effective semi-permanently. The humidity control material 11 will be described in detail below.

[0022] FIG. 4 is a cross-sectional view schematically showing the humidity control unit 10. As shown in FIG. 4, the humidity control material is supported on a support. That is, the humidity control unit 10 is a structure in which the humidity control material 11 is sandwiched between a plurality of supports 15. The humidity control unit 10 may also be a laminate in which a plurality of structures in which the humidity control material 11 is sandwiched between a plurality of supports 15 are stacked. Furthermore, the humidity control unit 10 may also be a laminate in which a support 15, a humidity control material 11, a support 15, a humidity control material 11, and a support 15 are stacked in this order. The humidity control material 11 is solid. Here, "solid" means at least a solid in a dry state, and also includes a material that deliquesces and liquefies when humidified, or a material that swells and releases water. The humidity control material 11 is solid, which reduces leakage or scattering into food or inside a refrigerator, making it hygienic.

[0023] The humidity conditioner 11 is preferably a deliquescent substance that absorbs moisture in the air and deliquesces. Deliquescent substances are classified into salts and water-soluble organic substances. Specific examples of salts include sodium formate, potassium formate, ammonium formate, sodium acetate, potassium acetate, lithium acetate, ammonium acetate, sodium lactate, potassium lactate, sodium benzoate, potassium benzoate, sodium propionate, potassium propionate, calcium chloride, lithium chloride, magnesium chloride, calcium chloride, lithium chloride, potassium chloride, sodium chloride, zinc chloride, aluminum chloride, lithium bromide, calcium bromide, potassium bromide, sodium hydroxide, sodium pyrrolidonecarboxylate, potassium carbonate, magnesium nitrate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium citrate. Among these, sodium formate, potassium formate, sodium acetate, potassium acetate, and potassium carbonate are preferred, as they absorb and release a large amount of moisture per weight.

[0024] Specific examples of water-soluble organic substances include sugars such as sucrose, pullulan, glucose, xylol, fructose, mannitol, and sorbitol, carboxylic acids such as citric acid, and amides such as urea.

[0025] Furthermore, the humidity-conditioning material 11 preferably contains a resin material. By containing a resin material, the resin material can absorb moisture in the air or the aqueous solution resulting from deliquescent substances. This reduces leakage or scattering of the humidity-conditioning material onto food or into the refrigerator.

[0026] Specific examples of resin materials include ionic resins and non-ionic resins. Examples of ionic resins include alkali metal salts of polyacrylic acid and starch-acrylate graft polymers. Examples of alkali metal salts of polyacrylic acid include sodium polyacrylate. Examples of non-ionic resins include vinyl acetate copolymers, maleic anhydride copolymers, polyvinyl alcohol, and polyalkylene oxides. Among these, sodium polyacrylate is preferred, as this material itself has the ability to absorb moisture at high humidity and release moisture at low humidity, thereby enhancing the humidity control ability of the humidity conditioner 11.

[0027] Furthermore, the resin material is preferably in powder or granular (bead-like) form. Being in powder or granular form allows for easy spreading on the support 15 and uniform humidity control in the surface direction. Powdered materials have a smaller average particle size than granular materials. Therefore, their contact area with air is larger, resulting in a higher rate of moisture absorption and desorption (humidity control rate). Because of their high humidity control rate, they can quickly absorb water vapor transpire from vegetables, suppressing condensation. When humidity drops, they quickly release moisture, preventing vegetables from drying out. On the other hand, granular materials have a larger average particle size, resulting in a higher moisture absorption and desorption rate (humidity control amount) per weight of resin material. Therefore, they can store a large amount of water transpire from vegetables, suppressing condensation, and release a large amount of water vapor during drying, preventing vegetables from drying out. In this way, by allowing a deliquescent substance and a resin material to coexist, the resin material absorbs the aqueous solution resulting from the deliquescent deliquescent of the deliquescent substance, and the absorbed resin material functions as a humidity control material. Furthermore, the resin material with humidity control function can adjust the humidity control speed and humidity control amount as desired by changing the average particle size, and can be designed according to the usage environment. Note that, in this disclosure, the average particle size of the powdered material generally refers to a few μm to a few mm, and the average particle size of the particulate material generally refers to a few mm to a few tens of mm.

[0028] Fig. 5 is a cross-sectional view showing a modified humidity conditioner 11 supported on a support 15. As shown in Fig. 5, the humidity conditioner 11 may be supported on an uneven support 15. In this way, it is possible to realize a humidity conditioner 11 with a high ratio of surface area to volume, and the rate of moisture absorption or release can be increased.

[0029] The support 15 that supports the humidity conditioner 11 is preferably made of a material that retains moisture. For example, it is made of hydrophilic fibers such as porous materials, nonwoven fabrics, and woven fabrics. In particular, nonwoven fabrics that have high water vapor permeability are preferred.

[0030] The carrier 15 may be in the form of a sheet, and may be formed into various shapes such as a flat, pleated, or honeycomb shape before use. For example, a sheet-like material may first be formed into a wave-like (fluted) shape using a corrugator, and then be bonded to a flat liner made of the same or a different material as the sheet using an adhesive to form an integrated structure. The carrier 15 may also be flexible. The carrier 15 may be deformable. In other words, it may be capable of being held in any shape (such as a bent or curved shape).

[0031] FIG. 6 is a diagram showing freshness preservation sheet 100 according to the first embodiment. As shown in FIG. 6, freshness preservation sheet 100 according to the first embodiment can be divided by cutting, and may have a plurality of divided freshness preservation sheets 101. Divided freshness preservation sheets 101 can precisely adjust the humidity in room 30. Furthermore, as shown in FIG. 6, it may have easy-to-tear sections 102 with perforations or multiple holes. This allows it to be easily divided into any size.

[0032] FIG. 7 is a diagram showing an example of how the freshness-preserving sheet 100 according to the first embodiment is used, showing a state in which the interior 30 is open. As shown in FIG. 7, vegetables are placed in the interior 30, such as the vegetable compartment of a refrigerator, and the freshness-preserving sheet 100 is placed on top of them. It is also preferable to place the freshness-preserving sheet 100 so that the humidity control unit 10 faces the vegetables. In this way, the humidity control unit 10 faces the vegetables, making it easier for the humidity control unit 10 to absorb water vapor Y released from the vegetables. This suppresses condensation in the interior 30, allowing the freshness of the object X to be maintained for a longer period of time. While FIG. 7 shows the vegetable compartment of a refrigerator, the freshness-preserving sheet according to the first embodiment can also be applied to vegetables stored in an insulated box, such as a polystyrene foam box, together with ice packs or ice storage materials.

[0033] FIG. 8 is a diagram showing an example of use of freshness-preserving sheet 100 according to the first embodiment, showing the state in which interior room 30 is open. FIG. 9 is a diagram showing an example of use of freshness-preserving sheet 100 according to the first embodiment, showing the state in which interior room 30 has been opened and then resealed. As shown in FIG. 8, when the refrigerator is pulled out to remove vegetables and interior room 30, such as a vegetable compartment, is opened, the humidity in interior room 30 decreases. Then, as shown in FIG. 9, when interior room 30 is resealed, freshness-preserving sheet 100 releases water vapor Y stored in humidity-conditioning unit 10, preventing the vegetables from drying out and maintaining the freshness of object X for a longer period of time. Furthermore, opening interior room 30 of the refrigerator increases the temperature of freshness-preserving sheet 100, making it easier for freshness-preserving sheet 100 to release moisture, which in turn releases more water vapor Y stored in humidity-conditioning unit 10 and prevents the vegetables from drying out.

[0034] In this way, when vegetables are removed from the vegetable compartment or other room 30, the amount of evaporation decreases due to the decrease in the content volume, and the humidity in the vegetable compartment or other room 30 decreases due to the circulation of cold air in the room 30. However, the freshness of the object X such as vegetables can be maintained by the supply of water vapor Y from the humidity control unit 10.

[0035] Here, the freshness-preserving sheet 100 according to the first embodiment comprises a humidity control section 10 and a moisture-release suppression section 20, and we will explain the case of a sheet with only a humidity control section 10 and a sheet with only a moisture-release suppression section 20.

[0036] FIG. 10 shows a sheet that does not have a moisture release suppression section 20. In other words, the sheet only has a humidity control section 10. In this case, when vegetables are placed in the vegetable compartment, water vapor Y is released from the vegetables. The water vapor Y is absorbed by the sheet that only has the humidity control section 10.

[0037] When the sheet is removed from the refrigerator and the interior 30, such as the vegetable compartment, is opened, or the sheet with only the humidity control section 10 is exposed to the outside air of the refrigerator, the humidity outside is lower than that inside the refrigerator, so water vapor Y is released from the sheet with only the humidity control section 10. However, since there is no moisture release suppression section 20 to suppress the release of moisture from the humidity control section 10, the water vapor Y absorbed in the sheet with only the humidity control section 10 is released in greater amounts than in the freshness-preserving sheet 100 of the first embodiment without suppressing the release of moisture.

[0038] Then, when the room 30 is sealed again, the amount of water vapor Y in the room 30 is small, so moisture such as water vapor Y is released from the sheet having only humidity conditioning section 10, but because there is no moisture release suppression section 20 to suppress moisture release from the humidity conditioning section 10, the amount of moisture contained in the sheet having only humidity conditioning section 10 is less than that of the freshness-preserving sheet 100 of the first embodiment, reducing the amount of moisture supplied to the vegetables and gradually reducing the freshness of the vegetables. Therefore, a sheet having only humidity conditioning section 10 cannot maintain the freshness of object X for a long period of time.

[0039] FIG. 11 shows a sheet that does not include a humidity control unit 10. That is, the sheet only includes a moisture release suppression unit 20. In this case, when vegetables are placed in the vegetable compartment, moisture such as water vapor Y is released from the vegetables. Since there is no humidity control unit 10 to absorb the moisture, the humidity in the room 30 increases.

[0040] When the refrigerator is pulled out and the interior 30, such as the vegetable compartment, is opened, moisture is not released because the humidity in the interior 30 is sealed in by the sheet with only the moisture release suppression unit 20 unless the sheet with only the moisture release suppression unit 20 is removed. As a result, the interior 30 becomes excessively humid, causing condensation and gradually reducing the freshness of the vegetables. Therefore, the freshness of the object X cannot be maintained for a long period of time if a sheet with only the moisture release suppression unit 20 is used.

[0041] Furthermore, when the refrigerator is pulled out and the interior 30, such as the vegetable compartment, is opened, and the sheet with only the moisture release suppression unit 20 that seals the interior 30 is removed, the water vapor Y inside the interior 30 is released. Then, when the interior 30 is sealed again, the sheet with only the moisture release suppression unit 20 does not have the function of releasing moisture such as water vapor Y, so when vegetables are placed inside the vegetable compartment 30, the humidity inside the interior 30, such as the vegetable compartment, drops further, and with repeated opening, the humidity continues to drop until the compartment eventually becomes dry. Therefore, a sheet with only the moisture release suppression unit 20 cannot maintain the freshness of the object X for a long period of time.

[0042] In this way, the freshness-preserving sheet 100 according to the first embodiment includes a humidity control section 10 and a moisture release suppression section 20, and the humidity control section 10 absorbs or releases moisture such as water vapor Y in the room 30, and the moisture release suppression section 20 suppresses moisture release from the humidity control section 10, thereby maintaining the freshness of the object X for a longer period of time. Note that in the drawings, the object X and the freshness-preserving sheet 100 are shown separated to illustrate the absorption or release of water vapor Y between the object X and the freshness-preserving sheet 100, but they may also be in contact. Because the humidity control section 10 of the freshness-preserving sheet according to the first embodiment is solid, the possibility of the humidity-conditioning material 11 adhering to the object X is extremely low even if they come into contact.

[0043] [Second embodiment] Fig. 12 is a cross-sectional view showing freshness preservation sheet 200 according to the second embodiment. As shown in Fig. 12, in freshness preservation sheet 200 according to the second embodiment, humidity control section 10 and moisture release suppression section 20 are spaced apart, with a space provided between humidity control section 10 and moisture release suppression section 20. Freshness preservation sheet 200 according to the second embodiment is structured so that water vapor Y released from humidity control section 10 does not flow out from the moisture release suppression section 20 side. In addition, spacer 40 is provided to separate humidity control section 10 and moisture release suppression section 20.

[0044] 12, the humidity control unit 10 absorbs and releases water vapor Y, absorbing and releasing moisture. On the other hand, the moisture release suppression unit 20 suppresses absorption of water vapor Y from the outside (outside air) of the moisture release suppression unit 20 and suppresses excessive release of water vapor Y from the humidity control unit 10, particularly suppressing moisture release from the humidity control unit 10 at times of low humidity. In this way, moisture in the room 30 can be absorbed or released, providing a humidity control function.

[0045] Furthermore, since the humidity control unit 10 and the moisture release suppression unit 20 are spaced apart, the water vapor Y released from the humidity control unit 10 can be held in the space between the humidity control unit 10 and the moisture release suppression unit 20. This increases the amount of water vapor released to the object X during drying, allowing the object X to remain fresh for a longer period of time.

[0046] [Third embodiment] Fig. 13 is a cross-sectional view showing a freshness preservation sheet 300 according to the third embodiment. As shown in Fig. 13, freshness preservation sheet 300 according to the third embodiment includes humidity control unit 10 which is a laminate of multiple humidity control units 10.

[0047] In this way, the humidity control amount can be ensured, and the humidity control unit 10 can absorb a larger amount of water vapor Y than that emitted from the object X, such as vegetables, whose freshness is to be maintained, and can also emit a larger amount of water vapor Y. Therefore, the freshness of the object X can be maintained for a longer period of time.

[0048] In addition, in freshness preservation sheet 300 according to the third embodiment, moisture release suppression members 20 may be spaced apart, similar to freshness preservation sheet 200 according to the second embodiment.

[0049] [Fourth embodiment] FIG. 14 is a cross-sectional view of a freshness-preserving sheet 400 according to a fourth embodiment. The freshness-preserving sheet 400 according to the fourth embodiment has multiple humidity control units, including a first humidity control unit 10 and a second humidity control unit 12, each containing a first humidity control material and a second humidity control material. The second humidity control unit 12 is disposed between the first humidity control unit 10 and the moisture-release suppression unit 20. The first humidity control material contains a first resin material, and the second humidity control material contains a second resin material. The average particle size of the first resin material is smaller than that of the second resin material. This allows the first humidity control unit to quickly absorb water vapor Y released from the object X. Furthermore, as the amount of moisture held by the first humidity control unit 10 increases, the amount of water vapor released toward the moisture-release suppression unit 20 also increases. The second resin material contained in the second humidity control unit 12 has a larger average particle size than the first resin material, allowing it to retain a larger amount of moisture. As a result, the first humidity control unit 10 prevents a sudden rise in humidity that occurs when vegetables are placed inside the room 30, greatly reducing the possibility of condensation. Furthermore, since the second humidity control unit 12 absorbs water vapor that the first humidity control unit alone cannot absorb, when the outside air becomes dry, water vapor is released from the second humidity control unit, and the freshness of the object X is maintained for a longer period of time.

[0050] The second humidity-regulating material contains a resin, at least one of a polyhydric alcohol and a deliquescent substance, and water, and has a target humidity. Here, having a target humidity means adjusting the relative humidity to approach a predetermined humidity range. Specifically, for example, if the target humidity is 50% RH, the humidity-regulating material absorbs moisture when the relative humidity is higher than 50% RH, and releases moisture when the relative humidity is lower than 50% RH. Typically, the target humidity correlates with the material and moisture content of the humidity-regulating material. By having the second humidity-regulating material maintain the target humidity, the indoor humidity can be maintained at around the target humidity. [Example]

[0051] Example 1 First, a moisture-proof sheet made of commercially available polyethylene with a thickness of 0.2 mm was prepared as the moisture-release suppression part. Next, a moisture-conditioning part with a thickness of 0.5 mm and a basis weight of 50 g / m was prepared. 2 A nonwoven fabric of Example 1 was sprayed with sodium polyacrylate having an average particle size of 200 μm as a resin material and sodium acetate as a deliquescent material, and the resulting nonwoven fabric was sandwiched between two nonwoven fabrics of the same thickness and basis weight and heat-pressed to obtain a humidity-conditioning sheet. The edges of the resulting humidity-conditioning sheet and a moisture-proof sheet were bonded together to obtain the freshness-keeping sheet of Example 1. Vegetables such as cabbage, broccoli, radish, carrots, and peppers were placed in a vegetable compartment (200 mm wide x 500 mm deep x 300 mm high) of a refrigerator, and the freshness-keeping sheet of Example 1, cut to 190 mm x 450 mm, was placed on top of the vegetables. The vegetable compartment was then closed, and the weight change and weight change rate of each vegetable were evaluated after 6 days. The external freshness of the vegetables and the state of condensation inside the compartment were observed.

[0052] Example 2 A humidity-conditioning material with a target humidity of 80% RH was obtained by impregnating sodium polyacrylate with an average particle size of 3 mm, which was used as a resin material with a larger particle size than the resin material of Example 1, with a 25% aqueous solution of sodium acetate. As shown in Figure 15, this was placed between the moisture-proof sheet of Example 1 and the humidity-conditioning sheet of Example 1, and they were stuck together, and the edges and nodes were glued together to obtain a freshness-keeping sheet of Example 2. Other conditions were the same as in Example 1.

[0053] (Comparative Examples 1 and 2) Comparative Example 1 was a sample without a freshness-preserving sheet, and Comparative Example 2 was a sample with only a moisture-proof sheet. These were cut to 190 mm x 450 mm in the same manner as in Examples 1 and 2, and then covered with the above-mentioned vegetables. Other conditions were the same as in Examples 1 and 2.

[0054] The results of the freshness retention evaluation test in the refrigerator vegetable compartment are shown in Table 1. As shown in Table 1, a weight loss was observed in all cases, and the amount of weight loss was similar in Examples 1 and 2, with the amount of weight loss being greater in Example 2 than in Example 1. Furthermore, in terms of the appearance of the vegetables, almost no change was observed in Examples 1 and 2, but the spinach in Comparative Examples 1 and 2 was noticeably wilted. Furthermore, no adhesion of humidity-regulating material was confirmed. Furthermore, when the state of condensation in the vegetable compartment was observed, there was less condensation in Example 2 than in Example 1. The results are summarized in Table 1.

[0055] [Table 1]

[0056] As described above, the freshness preservation sheets 100, 200, 300, and 400 according to the present disclosure contain a solid humidity-conditioning material, which reduces leakage of the humidity-conditioning material and keeps food and the inside of the refrigerator hygienic. Furthermore, the sheets have a humidity-conditioning function and can absorb or release moisture in the closed space to maintain freshness.

[0057] Example 3 As shown in Fig. 16, a refrigerator 500 is provided which includes a storage section 501 for storing an object X to be kept fresh, a cooling section 502 for cooling the air in the storage section 501, and a freshness preservation sheet 101 arranged so that the humidity control section 10 faces the object X. Furthermore, the cooling section 502 is provided with a collection section 503 for collecting water or ice generated by cooling the air in the storage section 501, and a discharge section 504 for discharging the water or ice accumulated in the collection section 503 to the outside of the storage section.

[0058] In this experiment, a prefabricated refrigerated warehouse measuring 3.6 m wide x 1.8 m deep x 1.9 m was used as storage unit 501, and cabbage, broccoli, radish, carrot, and pepper were used as object X, as in Example 1. Object X was contained in a plastic packaging box 505 (200 mm wide x 500 mm deep x 300 mm high) and placed on the floor of storage unit 501. Cooling unit 502 was a gas compression type that cools by compressing, condensing, and evaporating a refrigerant. The temperature inside the refrigerator was maintained at 3 to 10°C for six days, and the weight change of object X was measured between the initial and six days. After six days, object X showed almost no weight change and its appearance maintained its freshness. On the other hand, without freshness-preserving sheet 101, the weight of object X clearly decreased, the cabbage discolored, and the radish and broccoli had voids in their cross sections, indicating their dryness.

[0059] From this, it can be seen that the air inside the storage unit 501 of the present disclosure is in a dry state due to the water vapor undergoing a phase transition to water or ice by the cooler, but by installing the freshness preservation sheet 101 of the present disclosure, the object X is prevented from drying out, and the humidity control effect of the humidity control unit 10 maintains the freshness of the vegetables.

[0060] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0061] For example, a term that appears at least once in the specification or drawings together with a different term having a broader or equivalent meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configuration and operation of the freshness-keeping sheet are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible.

Claims

1. a humidity control section including a humidity control material; and a moisture release suppressing section having a water vapor permeability lower than that of the humidity control section and suppressing moisture release from the humidity control section; The humidity conditioner is a solid, A freshness-keeping sheet, characterized in that the moisture-release suppressing section is laminated on the humidity-conditioning section, and the humidity-conditioning section and the moisture-release suppressing section are spaced apart.

2. 2. The freshness-preserving sheet according to claim 1, wherein the moisture release suppression portion is made of a material whose water vapor permeability changes depending on humidity.

3. 3. The freshness-preserving sheet according to claim 1, wherein the moisture release suppression section includes a hydrophilic polymer and a hydrophobic polymer, and the weight ratio of the hydrophobic polymer is higher on the humidity control section side.

4. 3. The freshness-keeping sheet according to claim 1, wherein the humidity-conditioning material contains a deliquescent substance that absorbs moisture in the air and deliquesces.

5. A freshness-preserving sheet as described in Claim 4, characterized in that the deliquescent substance includes at least one selected from the group consisting of salts or water-soluble organic substances.

6. 6. The freshness-preserving sheet according to claim 5, wherein the salt is selected from the group consisting of sodium formate, potassium formate, sodium acetate, potassium acetate, and potassium carbonate.

7. 5. The freshness-keeping sheet according to claim 4, wherein the humidity-conditioning material comprises a resin material that absorbs moisture in the air or an aqueous solution of the deliquescent substance.

8. 8. The freshness-keeping sheet according to claim 7, wherein the resin material is in the form of a powder or particles.

9. 3. The freshness-keeping sheet according to claim 1, wherein the humidity-conditioning material is supported on a support.

10. 10. The freshness-preserving sheet according to claim 9, wherein the carrier is a nonwoven fabric or a woven fabric.

11. 3. The freshness-keeping sheet according to claim 1, wherein either the humidity control section or the moisture release suppression section is layered.

12. 3. The freshness-keeping sheet according to claim 1, wherein the humidity control section and the moisture release suppression section are layered and face each other.

13. The freshness-preserving sheet according to claim 1 or 2, characterized in that a spacer is provided between the humidity control section and the moisture release suppression section to separate the humidity control section and the moisture release suppression section.

14. 3. The freshness-keeping sheet according to claim 1, further comprising an easily tearable portion.

15. 3. The freshness-keeping sheet according to claim 1, wherein the humidity control section is a laminate of a plurality of humidity control sections.

16. The humidity control unit has a plurality of humidity control units, The first humidity control section contains a first humidity control material, The freshness-keeping sheet according to claim 1 or 2, characterized in that the second humidity control section contains a second humidity control material and is provided between the first humidity control section and the moisture release suppression section.

17. The freshness-preserving sheet according to claim 16, characterized in that the first resin material contained in the first humidity-regulating material has a smaller average particle size than the second resin material contained in the second humidity-regulating material.

18. The freshness-keeping sheet described in claim 16, characterized in that the second humidity-regulating material contains a resin, a polyhydric alcohol, and at least one deliquescent substance that absorbs moisture in the air and deliquesces, and water, and has a target humidity.

19. A refrigerator equipped with the freshness-preserving sheet according to claim 1 or 2, a storage unit for storing an object to be kept fresh; a cooling unit for cooling the air in the storage unit; Equipped with The freshness preservation sheet is arranged so that the humidity control section faces the object to be kept fresh.

20. 20. The refrigerator according to claim 19, wherein the cooling unit cools water vapor in the air in the storage unit and causes a phase transition to water or ice.

21. The refrigerator according to claim 19, wherein the cooling unit is provided with a discharge unit that cools water vapor in the air in the storage unit and discharges the water or ice that has undergone phase transition outside the storage unit.

Images