Heat insulating container

Abstract

A heat insulating container (70) comprises: a housing space (71); and a wall (72) having an interior surface which encloses the housing space (71). The wall (72) is configured such that the thermal conductivity in a thickness direction orthogonal to the interior surface is less than the thermal conductivity in a surface direction that is along the interior surface and that is orthogonal to the thickness direction.

Description

thermal container

[0001] The present disclosure relates to thermal containers.

[0002] A known example of a thermally insulating container is the thermally conductive inner container disclosed in Patent Document 1. This inner container is made of a metal such as aluminum, an aluminum alloy, or copper, and contains a target object, which is placed inside the container together with a heat storage material.

[0003] JP 2013-10523 A

[0004] The inner container with high thermal conductivity described in Patent Document 1 is cooled by a heat storage material, maintaining the internal space at a predetermined temperature (e.g., 2°C to 8°C). However, an inner container with high thermal conductivity also transfers external warm heat, canceling out the cooling effect of the heat storage material and shortening the cooling time. In contrast, if the thermal conductivity of the inner container is reduced, the heat storage material will not melt uniformly, causing temperature variations over the course of the cooling time, resulting in an uneven temperature in the internal space of the inner container.

[0005] The present disclosure has been made to solve such problems, and aims to provide a thermal container that can achieve uniform temperature in the storage space and prolong the thermal retention time.

[0006] The thermal container according to the first aspect of the present disclosure comprises a storage space and a wall having an inner surface surrounding the storage space, and the wall has a greater thermal conductivity in a plane direction along the inner surface, perpendicular to the thickness direction, than in a thickness direction perpendicular to the inner surface.

[0007] With this configuration, the wall has a high thermal conductivity in the surface direction, which reduces temperature unevenness in the surface direction of the wall and the heat storage material cooling the wall. Furthermore, the wall has a low thermal conductivity in the thickness direction, which reduces heat conduction from the outside of the thermal insulation container to the storage space. This allows for a more uniform temperature in the storage space and a longer heat retention time.

[0008] In a second aspect of the present disclosure, the thermal container of the first aspect has a first wall having a thermal conductivity in the surface direction greater than the thermal conductivity in the thickness direction, and the first wall is formed from a binder resin and a thermally conductive filler having a thermal conductivity higher than the thermal conductivity of the binder resin and blended into the binder resin.

[0009] According to this configuration, since the wall contains a thermally conductive filler with high thermal conductivity, the wall is efficiently cooled by the heat storage material, and therefore the storage space surrounded by the wall can be cooled to a predetermined temperature by the cooled wall.

[0010] A thermally insulated container according to a third aspect of the present disclosure is the second aspect, in which the thermally conductive filler has shape anisotropy and is arranged in the wall so that the dimension in the thickness direction is smaller than the dimension in the surface direction.

[0011] This configuration allows heat to move more easily in the planar direction than in the thickness direction due to the thermally conductive filler, thereby reducing heat conduction from the outside of the insulated container to the storage space and temperature unevenness along the surface of the wall, thereby achieving a more uniform temperature in the storage space and a longer heat retention time.

[0012] The thermally-conductive filler according to a fourth aspect of the present disclosure is an insulating container according to the second or third aspect. This configuration allows radio waves to pass through the wall. Therefore, for example, if a thermometer and a wireless device capable of transmitting the temperature detected by the thermometer are housed in the thermally-contained container, the wireless device can transmit the temperature information detected by the thermometer to the outside of the thermally-contained container via radio waves. This allows temperature information of the storage space to be obtained outside the thermally-contained container without opening it, thereby reducing the temperature rise in the storage space due to opening and closing the thermally-contained container, thereby achieving a uniform temperature in the storage space and a longer heat retention time.

[0013] In a fifth aspect of the present disclosure, in any of the first to fourth aspects, the thermal container has a first wall in which the thermal conductivity in the surface direction is greater than the thermal conductivity in the thickness direction, and the ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the surface direction of the first wall is 0.2 or more and less than 0.8.

[0014] This configuration makes it possible to achieve both reduced heat conduction from the outside of the insulated container to the storage space due to the low thermal conductivity in the thickness direction of the wall, and reduced temperature unevenness in the wall due to the high thermal conductivity in the surface direction of the wall.

[0015] The thermal container according to a sixth aspect of the present disclosure is any one of the first to fifth aspects, wherein the wall has a first wall having a thermal conductivity in the surface direction greater than the thermal conductivity in the thickness direction, and a second wall made of resin, and the first wall is laminated on at least one of the inner and outer surfaces of the second wall.

[0016] With this configuration, the thickness of the first wall can be reduced by supporting the first wall with the second wall, which reduces the cost of the insulated container and reduces the heat conduction from the outside of the insulated container to the storage space.

[0017] In a seventh aspect of the present disclosure, the thermal container of the sixth aspect is configured such that the thickness of the first wall in the thickness direction is 1 mm or less. This configuration makes it possible to keep the cost of the thermal container low while keeping heat conduction from the outside of the thermal container to the storage space low.

[0018] An insulated container according to an eighth aspect of the present disclosure is a thermal container according to the sixth or seventh aspect, wherein the walls include a side wall having a pair of openings, a top wall that covers one of the pair of openings in an openable and closable manner, and a bottom wall that covers the other of the pair of openings, and the side wall has the first wall and the second wall, and at least one of the top wall and the bottom wall does not have the first wall but has the second wall.

[0019] With this configuration, the cost of the insulated container can be reduced because at least one of the top wall and the bottom wall does not have the first wall. Also, because the side wall has the first wall, heat is conducted between the top wall and the bottom wall via the first wall, which makes it possible to uniform the temperature in the storage space surrounded by the side wall, top wall, and bottom wall and to lengthen the heat retention time.

[0020] According to the present disclosure, it is possible to provide a thermal container that can achieve uniform temperature in the storage space and a long heat retention time.

[0021] FIG. 1 is a cross-sectional view of a vacuum insulated container according to a first embodiment of the present disclosure. FIG. 2 is an assembly drawing, seen from an oblique direction, showing the external configuration of a heat storage unit housed in the vacuum insulated container of FIG. 1. FIG. 3 is a schematic diagram showing a cross section perpendicular to the front-to-rear direction of the thermal insulation container of the heat storage unit of FIG. 2. FIG. 4 is a schematic diagram showing a method for manufacturing the wall of the cold insulation container of FIG. 3. FIG. 5 is a cross-sectional view of a vacuum insulated container according to a second embodiment of the present disclosure. FIG. 6 is a graph showing the relationship between the thickness of a first wall and the thermal conductivity of the wall in the surface direction. FIG. 7 is a graph showing the relationship between the thickness of the first wall and the thermal resistance conductivity of the wall in the thickness direction. FIG. 8 is a graph showing the relationship between the thickness of the first wall and the temperature variation in the storage space. FIG. 9 is a cross-sectional view of a vacuum insulated container according to a first modification. FIG. 10 is a cross-sectional view of a vacuum insulated container according to a second modification. FIG. 11 is a cross-sectional view of a vacuum insulated container according to the second modification.

[0022] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the same or corresponding elements are denoted by the same reference numerals throughout the drawings.

[0023] (Embodiment 1) The vacuum insulated container 10 shown in the example of Figure 1 is used for transporting and storing items such as medicines, specimens, and food. This vacuum insulated container 10 includes an outer bag 20, a protective box 30, an insulated container body 40, an insulated lid body 50, and a heat storage unit 60. In the following description, the side of the insulated lid body 50 relative to the insulated container body 40 will be referred to as "upper," and the opposite side will be referred to as "lower." Furthermore, directions that intersect (e.g., perpendicular to) the up-down direction and intersect (e.g., perpendicular to) each other will be referred to as the left-right direction and the front-rear direction. However, the arrangement of the vacuum insulated container 10 is not limited to this.

[0024] The outer bag 20 is made of a flexible fabric made of synthetic fibers such as nylon or polyester, and has a rectangular parallelepiped bag shape with an opening on the top surface that leads to the internal space, and a plate-like lid that can open and close this opening. Handles 21 that can be held by hand are attached to each of the left and right sides of the outer bag 20, and a belt 22 is stretched between the left and right sides. A protective box 30 and an insulated lid 50 are housed inside the outer bag 20.

[0025] The protective box 30 is a protective member made of a foam material such as polyethylene foam, and has a rectangular parallelepiped shape with an opening on the top surface that leads to the internal space. The outer surface of the protective box 30 is covered with the exterior bag 20, and the insulating container body 40 is housed inside the protective box 30.

[0026] The insulated container 40 includes, for example, a first outer skin 41 and a first core 42. The first outer skin 41 is a molded body of a non-metallic material, has gas barrier properties, and has, for example, a double-wall structure to form an internal space. The first core 42 is a non-metallic porous material, for example, an open-cell foam such as open-cell urethane foam, a foamed resin material such as polystyrene foam, a fiber aggregate, or an aggregate of inorganic fine particles. The first core 42 is housed inside the first outer skin 41, and the internal pressure of the first outer skin 41 is lower than the external pressure, for example, reduced to a predetermined pressure or lower, and the first outer skin 41 is sealed. The insulated container 40 has a rectangular parallelepiped shape with an opening on the top surface that leads to the internal space. The outer surface of the insulated container 40 is covered by a protective box 30, and a heat storage unit 60 is housed inside the insulated container 40.

[0027] The insulated lid 50 has a rectangular, flat plate shape and covers the opening of the insulated container 40 in an openable and closable manner. The insulated lid 50 includes a second outer skin 51 and a second core 52. The second outer skin 51 is made of a flexible film containing a metal layer and having gas barrier properties, and has a bag shape. The second core 52 is a non-metallic porous material, such as an open-cell foam such as open-cell urethane foam, a foamed resin material such as polystyrene foam, a fiber aggregate, or an aggregate of inorganic fine particles. The second outer skin 51 is housed inside the second outer skin 51, and the internal pressure of the second outer skin 51 is lower than the external pressure, e.g., reduced to a predetermined pressure or lower, thereby sealing the second outer skin 51. The outer surface of the insulated lid 50 is covered by the outer bag 20.

[0028] In such a vacuum insulated container 10, an insulated space is formed as an internal space surrounded by the insulated container body 40 and the insulated lid body 50 that covers the opening of the insulated container body 40. A heat storage unit 60 is housed in this insulated space, and an item A, such as a medicine or a specimen, is housed in the heat storage unit 60. As a result, the temperature around the item formed by the heat storage unit 60 is maintained for a long period of time by the insulated container body 40 and the insulated lid body 50.

[0029] 2 and 3, the heat storage unit 60 includes a basket 61, multiple heat storage materials 62, and an insulated container 70. The basket 61 is a container made of a non-metallic material such as resin, and has a shallow box shape with an opening at the top. The basket 61 has a pair of upwardly extending extensions 61a on the left and right sides, and a belt 61b is stretched between the pair of extensions 61a. The basket 61 has substantially the same shape as the internal space of the insulated container 40 (FIG. 1), but is slightly smaller than the internal space. The basket 61 is accommodated in the internal space of the insulated container 40, with its outer surface aligned with the internal surface of the insulated container 40.

[0030] For example, six heat storage materials 62 surround the hexahedral insulated container 70, with each heat storage material 62 arranged on each side of the insulated container 70. The heat storage material 62 has a flat plate shape and is filled in a pack made of a non-metallic material such as resin. The heat storage material 62 suppresses temperature changes by utilizing latent heat and sensible heat generated when the state changes between solid, liquid, and gas. The cold storage material 62, which is the heat storage material with a cooling function, cools the insulated container 70 by absorbing heat when it changes from a cooled and solidified solid state to a liquid state at its melting point. The heat storage material is a substance whose state change temperature (e.g., melting point) corresponds to a predetermined temperature (e.g., a temperature of 2°C or higher and 8°C or lower) in the storage space 71 of the insulated container 70, and known materials such as inorganic hydrates and organic hydrates can be used.

[0031] <Thermal Insulation Container> The thermal insulation container 70 has an accommodation space 71, which is its internal space, and a plurality of walls 72. The wall 72 has, for example, a flat plate shape and has an inner surface 72i, an outer surface 72o, and an end surface 72g.

[0032] The inner surface 72i surrounds the periphery of the storage space 71. The outer surface 72o is disposed farther from the storage space 71 than the inner surface 72i in the thickness direction of the wall 72. The inner surface 72i and the outer surface 72o have a flat rectangular shape and are arranged parallel to a plane direction perpendicular to the thickness direction. The thickness of the wall 72 between the inner surface 72i and the outer surface 72o in the thickness direction is constant. The end surface 72g is connected to the outer peripheral edge of the inner surface 72i and the outer peripheral edge of the outer surface 72o, has an area smaller than those of the inner surface 72i and the outer surface 72o, and is arranged parallel to the thickness direction.

[0033] The multiple walls 72 of the insulated container 70 include, for example, a top wall 72a, a bottom wall 72b, and side walls. The side walls include, for example, a front wall 72c, a rear wall 72d, a left side wall 72e, and a right side wall 72f. The front wall 72c and the rear wall 72d are spaced apart in the front-to-rear direction so that their inner surfaces 72i face each other. The left side wall 72e and the right side wall 72f are spaced apart in the left-to-right direction so that their inner surfaces 72i face each other. These four side walls 72c to 72f are connected to adjacent side walls 72c to 72f to form cylindrical side walls having rectangular upper and lower openings.

[0034] The bottom wall 72b is equal to or larger than the lower opening of the cylindrical side wall. The bottom wall 72b is connected to the lower ends of the side walls 72c to 72f so as to cover the lower opening. The bottom wall 72b and the side walls 72c to 72f are shaped like a rectangular parallelepiped with an upper opening on the top surface that leads to the internal space, and form the container portion of the thermal insulation container 70.

[0035] The top wall 72a is larger than or equal to the upper opening of the cylindrical side wall. The top wall 72a is connected to the rear side wall 72d so as to openably cover the upper opening, forming a lid for the insulated container 70. When the top wall 72a covers the upper opening of the container, the top wall 72a and the bottom wall 72b are spaced apart in the vertical direction so that their inner surfaces 72i face each other. As a result, the storage space 71 of the insulated container 70 is covered by six walls 72.

[0036] In this heat storage unit 60, the lower heat storage material 62 is placed on the inner bottom surface of the basket 61. Next, the heat-insulating container 70 is placed on the lower heat storage material 62 so that the outer surface 72o of the bottom wall 72b faces the upper surface of the lower heat storage material 62. Then, the heat storage material 62 is inserted into the gaps between the outer surfaces 72o of each of the side walls 72c to 72f and the inner side surfaces of the basket 61 that face each of the side walls 72c to 72f. Then, the upper heat storage material 62 is placed on the outer surface 72o of the top wall 72a. As a result, the heat-insulating container 70 is surrounded by the heat storage material 62, with each of the six walls 72 in contact with the heat storage material 62.

[0037] Here, the gap between the outer surface 72o of each of the side walls 72c to 72f and the inner side surface of the basket 61 is equal to or approximately equal to the thickness of the heat storage material 62 between the surface of the heat storage material 62 facing the outer surface 72o of the side walls 72c to 72f and the surface of the heat storage material 62 facing the inner side surface of the basket 61. Therefore, the heat storage material 62 inserted into the gap contacts the thermal storage container 70 and fills the gap between the thermal storage container 70 and the basket 61. As a result, the heat storage material 62 efficiently cools the thermal storage container 70 while supporting the thermal storage container 70 relative to the basket 61, thereby reducing vibrations of the thermal storage container 70 and the contents A contained therein.

[0038] The upper surface of the lower heat storage material 62 has an area equal to or larger than the area of ​​the outer surface 72o of the opposing bottom wall 72b, and covers the entire outer surface 72o of the bottom wall 72b. Note that, like the lower heat storage material 62, the surfaces of the upper, front, rear, left, and right heat storage materials 62 also have an area equal to or larger than the area of ​​the outer surface 72o of the opposing wall 72, and cover the entire outer surface 72o of that wall 72. Therefore, each wall 72 of the thermal storage container 70 is uniformly cooled by the heat storage material 62 in a direction along the surface, and the storage space 71 surrounded by the cooled walls 72 is cooled to and maintained at a predetermined temperature.

[0039] <Walls of the Insulated Container> The wall 72 of the insulated container 70 is made of a first wall 75. The first wall 75 has a thermal conductivity c2 in the surface direction that is greater than the thermal conductivity c1 in the thickness direction. Therefore, the wall 72 has a thermal conductivity c2 in the surface direction that is greater than the thermal conductivity c1 in the thickness direction. Therefore, in the wall 72, the amount of heat transferred per unit time per unit area perpendicular to the direction of heat transfer is greater in the surface direction than in the thickness direction. In the example of FIG. 3 , the thickness directions of the top wall 72a and the bottom wall 72b are vertical, the thickness directions of the front wall 72c and the rear wall 72d are front-to-back, and the thickness directions of the left wall 72e and the right wall 72f are horizontal.

[0040] For example, the ratio c1 / c2 of the thermal conductivity c1 in the thickness direction to the thermal conductivity c2 in the surface direction of the first wall 75 of the wall 72 is 0.2 or more and less than 0.8. For example, the thermal conductivity c1 in the thickness direction of the first wall 75 of the wall 72 is 0.5 W / mK or more and 2.5 W / mK or less, and the thermal conductivity c2 in the surface direction is 1 W / mK or more and 5 W / mK or less.

[0041] For example, if heat were to travel from the outside of the insulated container 70 through the wall 72 in the thickness direction to reach the storage space 71, the temperature of the storage space 71 would rise, shortening the cold retention time of the insulated container 70. In contrast, because the thermal conductivity c1 of the wall 72 in the thickness direction is low, the amount of heat transferred from the outer surface 72o to the inner surface 72i of the wall 72 is kept small. This reduces the amount of heat transferred from the outside of the insulated container 70 through the wall 72 to the storage space 71, thereby lengthening the heat retention time in the storage space 71.

[0042] Furthermore, because the heat storage material 62 melts from its surface, the temperature of the heat storage material 62 is lower toward the center of the heat storage material 62. Therefore, the wall 72 of the insulated container 70, which is cooled by the heat storage material 62, tends to have a lower temperature in the surface direction toward the center than toward the outer periphery. In contrast, because the thermal conductivity c2 of the wall 72 in the surface direction is large, heat easily moves in the surface direction of the wall 72, and the temperature of the wall 72 is made uniform in the surface direction. Therefore, the temperature of the storage space 71 surrounded by the wall 72 can be made uniform.

[0043] In this way, the temperature of the wall 72 is made uniform in the surface direction, and the temperature of the heat storage material 62 in contact with the wall 72 is also made uniform in the surface direction. Therefore, the melting distribution of the heat storage material 62 in the surface direction is made uniform, and it is possible to prolong the uniform cold insulation effect of the heat storage material 62. Therefore, it is possible to maintain a uniform temperature state in the storage space 71 surrounded by the wall 72 for a long period of time.

[0044] The first wall 75 of the wall 72 is formed of a binder resin 73 and a thermally conductive filler 74. The thermally conductive filler 74 has a thermal conductivity higher than that of the binder resin 73 and is blended into the binder resin 73. The thermally conductive filler 74 with such high thermal conductivity allows the wall 72 to be efficiently cooled by the heat storage material 62. This makes it possible to uniformize the temperature in the storage space 71 surrounded by the wall 72.

[0045] The binder resin 73 is a resin, such as a thermoplastic resin, that can be used to form the wall 72 even when the thermally conductive filler 74 is blended therein. Examples of the binder resin 73 include ABS, polypropylene, polycarbonate, polybutylene terephthalate, nylon 6, nylon 66, polyphenylene sulfide, and polystyrene.

[0046] The thermally conductive filler 74 is, for example, an inorganic substance such as magnesium oxide (MgO) or anhydrous magnesium carbonate (MgCO ３ , magnesium hydroxide Mg(OH) ２ , silicon oxide (fused silica) SiO ２ , aluminum oxide Al ２ O ３ , hexagonal boron nitride BN, silicon nitride Si ３ N ４ , aluminum nitride AlN, talc Mg ３ Si ４ O １０ (OH) ２ Examples include:

[0047] The thermally conductive filler 74 has shape anisotropy, and examples thereof include plate-like shapes such as flat and scale-like, and needle-like shapes such as rod-like and fibrous. The thermally conductive filler 74 is oriented so that its longitudinal direction is parallel or nearly parallel to the surface direction of the wall 72. The angle between the longitudinal direction and the surface direction of the thermally conductive filler 74 is equal to or greater than 0 degrees and is smaller than the angle between the longitudinal direction and the thickness direction of the thermally conductive filler 74. Therefore, the thermally conductive filler 74 is arranged in the wall 72 so that its dimension in the thickness direction is smaller than its dimension in the surface direction.

[0048] For example, the plate-shaped thermally conductive filler 74 has multiple surfaces, and the largest of the multiple surfaces is oriented so that the main surface is parallel or nearly parallel to the inner surface 72i of the wall 72. The angle between the main surface of the plate-shaped thermally conductive filler 74 and the surface direction is 0 degrees or greater and smaller than the angle between the main surface and the thickness direction. Furthermore, the needle-shaped thermally conductive filler 74 is oriented so that its longitudinal direction is parallel or nearly parallel to the inner surface 72i of the wall 72. The angle between the longitudinal direction of the needle-shaped thermally conductive filler 74 and the surface direction is 0 degrees or greater and smaller than the angle between the longitudinal direction of the thermally conductive filler 74 and the thickness direction.

[0049] For this reason, the thermally conductive filler 74 is arranged such that the maximum dimension in the planar direction is greater than the maximum dimension in the thickness direction in the wall 72. As a result, the ratio of the thermally conductive filler 74 to the binder resin 73 per unit length in the planar direction of the wall 72 is greater than the ratio of the thermally conductive filler 74 to the binder resin 73 per unit length in the thickness direction of the wall 72.

[0050] Because the thermal conductivity c1 in the thickness direction of the wall 72 is smaller than the thermal conductivity c2 in the surface direction of the wall 72, it is possible to reduce heat conduction from the outside of the thermally-insulated container 70 to the storage space 71 and to extend the heat retention time in the storage space 71. On the other hand, because the thermal conductivity c2 in the surface direction of the wall 72 is larger than the thermal conductivity c1 in the thickness direction of the wall 72, it is possible to uniformize the temperature in the surface direction of the wall 72 and the heat storage material 62 of the thermally-insulated container 70.

[0051] The thermally conductive filler 74 and the binder resin 73 have, for example, insulating properties. In this case, the wall 72 made of the binder resin 73 and the thermally conductive filler 74 mixed therein has insulating properties and does not easily allow electricity to pass through.

[0052] For example, a thermometer B (FIG. 1) and a wireless device C (FIG. 1) are housed in a housing space 71 surrounded by an insulating wall 72. The thermometer B is electrically connected to the wireless device C, and detects the temperature in the housing space 71 and outputs the temperature to the wireless device C. The wireless device C transmits the temperature detected by the thermometer B via wireless communication. The radio waves from the wireless device C pass through the insulating wall 72.

[0053] Another wireless device capable of wireless communication with wireless device C is placed outside the vacuum insulated container 10. This other wireless device receives the temperature detected by thermometer B transmitted from wireless device C. This makes it possible to obtain the temperature in the storage space 71 of the insulated container 70 from outside the insulated container 70 without opening the insulated container 70 or providing a through-hole in the insulated container 70 for pulling the cord of thermometer B out of the insulated container 70. This makes it possible to reduce temperature unevenness in the storage space 71 caused by opening and closing the insulated container 70 and the through-hole.

[0054] In addition, the heat storage material 62, basket 61, insulated container body 40, protective box 30, exterior bag 20, and the like located outside the heat-retaining container 70 in the vacuum insulated container 10 are also formed of, for example, non-metallic materials. In this case, radio waves from the wireless device C can be received by another wireless device outside the vacuum insulated container 10. This reduces temperature unevenness in the storage space 71 caused by opening and closing the vacuum insulated container 10 and the through holes.

[0055] The thermally conductive filler 74 may not contain carbon, for example. Because carbon is dark in color, it is difficult to color the wall 72 that contains carbon. In contrast, if the thermally conductive filler 74 does not contain carbon, it is easy to color the wall 72 that contains the thermally conductive filler 74. This improves the design of the thermally-insulated container 70 and improves its distinguishability by color.

[0056] <Wall Forming Method> The wall 72 containing such thermally conductive filler 74 is formed, for example, by injection molding. In the example of FIG. 4 , binder resin 73 mixed with thermally conductive filler 74 is heated and melted in a cylinder 80. A nozzle 82 at the tip of this cylinder 80 is connected to an injection channel 84 of a mold 83, and the binder resin 73 is extruded from the cylinder 80 by a screw 81. As a result, the binder resin 73 is forced from the cylinder 80 through the nozzle 82 and the injection channel 84 into a cavity 85, which is the internal space of the mold 83. Then, when the binder resin 73 cools and solidifies in the cavity 85 of the mold 83, the mold 83 is divided, and the binder resin 73 mixed with thermally conductive filler 74 is removed from the cavity 85 as the wall 72.

[0057] The nozzle 82 of the cylinder 80 is a columnar space having an axis extending in the surface direction. The injection path 84 is a columnar space having an axis extending in the surface direction, and one end in the surface direction is connected to the cavity 85. When the binder resin 73 is injected from the cylinder 80 into the mold 83, the other end of the injection path 84 is connected to the nozzle 82. This allows the cylinder 80 to communicate with the cavity 85 via the nozzle 82 and the injection path 84. The cavity 85 is a space with a shape and size corresponding to the shape and size of the wall 72, and has, for example, a rectangular flat plate shape. The inner surface of the mold 83 surrounds the cavity 85 and has surfaces that form the inner surface 72i, outer surface 72o, and end surface 72g of the wall 72. The surface of the inner surface of the mold 83 that forms the end surface 72g of the wall 72 is connected to the injection path 84 and is perpendicular to the surface direction.

[0058] As described above, the nozzle 82 and the injection path 84 extend along the surface direction, and the binder resin 73 containing the thermally conductive filler 74 moves through the nozzle 82 and the injection path 84 in the surface direction. Furthermore, the cross sections of the nozzle 82 and the injection path 84 perpendicular to the surface direction are equal or nearly equal to each other and smaller than the cross sections of the cylinder 80 and the cavity 85 perpendicular to the surface direction. Therefore, while the binder resin 73 containing the thermally conductive filler 74 passes through the nozzle 82 and the injection path 84 in the surface direction, the longitudinal direction of the thermally conductive filler 74 is aligned parallel or nearly parallel to the surface direction. As a result, the thermally conductive filler 74 in the binder resin 73 injected from the injection path 84 into the cavity 85 is oriented so that its longitudinal direction is parallel or nearly parallel to the surface direction.

[0059] (Embodiment 2) In the insulated container 70 according to embodiment 1, the entire wall 72 is formed by the first wall 75. In contrast, in the insulated container 70 according to embodiment 2, as shown in the example of Fig. 5, a portion of the wall 72 is formed by the first wall 75. Because the wall 72 has the first wall 75, the thermal conductivity c2 in the planar direction is greater than the thermal conductivity c1 in the thickness direction.

[0060] Specifically, the wall 72 includes a first wall 75 having a thermal conductivity c2 in the planar direction that is greater than a thermal conductivity c1 in the thickness direction, and a second wall 76 made of resin. The first wall 75 is layered on the outer surface of the second wall 76. The first wall 75 and the second wall 76 each have, for example, a flat rectangular shape with flat inner and outer surfaces, forming a plate shape. The size of the inner surface of the first wall 75 is equal to or greater than the size of the outer surface of the second wall 76, and the inner surface of the first wall 75 covers the entire outer surface of the second wall 76. In this way, the first wall 75 and the second wall 76 are layered in the thickness direction to form the wall 72.

[0061] In this wall 72, the inner surface of the first wall 75 and the outer surface of the second wall 76 are in contact with each other, the inner surface 72i of the wall 72 is formed by the inner surface of the second wall 76, and the outer surface 72o of the wall 72 is formed by the outer surface of the first wall 75. As a result, the first wall 75 is in contact with the heat storage material 62 and is uniformly cooled in the surface direction by the heat storage material 62. Heat is then transferred between the first wall 75 and the second wall 76, cooling the entire wall 72 and cooling the temperature of the storage space 71 surrounded by the wall 72 to a predetermined temperature. Here, the wall 72 has a thermal conductivity c2 in the surface direction that is greater than the thermal conductivity c1 in the thickness direction, so that the temperature of the storage space 71 can be made uniform and the heat retention time can be extended.

[0062] In the insulated container 70 shown in FIG. 5 , the second walls 76 in the bottom wall 72b and each of the side walls 72c to 72f, i.e., five second walls 76 in total, are arranged to form a container shape. The container portion consisting of these second walls 76 is box-shaped and open at the top, and is formed as a single unit. First walls 75 are fixed to the outer surfaces of the container portions of the second walls 76 with fixing members such as adhesive or double-sided tape. As a result, the bottom wall 72b and the side walls 72c to 72f, together with the first walls 75 and the second walls 76 laminated on the inner surfaces thereof, form the container portion of the insulated container 70.

[0063] The second wall 76 of the top wall 72a is provided so as to be able to open and close the upper opening of the container portion of the second wall 76. The first wall 75 is fixed to the outer surface of the second wall 76 with a fixing member such as an adhesive or double-sided tape. As a result, the top wall 72a is formed by the first wall 75 and the second wall 76 laminated on the inner surface thereof, and forms a lid portion of the insulated container 70 that can open and close and cover the upper opening of the container portion of the insulated container 70.

[0064] The thermal conductivity of the second wall 76 is lower than that of the first wall 75. For example, the thermal conductivity of the second wall 76 in the thickness direction is equal to the thermal conductivity in the surface direction, and the difference between the two is 0. The second wall 76 has greater mechanical strength, such as tensile strength, compressive strength, and impact strength, than the first wall 75, and is made of a resin such as polypropylene resin.

[0065] The wall 72 has the second wall 76, which has excellent mechanical strength. This makes it possible to reduce the thickness of the first wall 75 while reducing the risk of damage to the insulated container 70. By reducing the thickness of the first wall 75, costs can be reduced and the heat conduction of the wall 72 in the thickness direction can be suppressed, thereby making the temperature in the storage space 71 uniform and lengthening the heat retention time.

[0066] The ratio c1 / c2 of the thermal conductivity c1 in the thickness direction to the thermal conductivity c2 in the surface direction of the first wall 75 is 0.2 or greater and less than 0.8. The first wall 75 is formed of a binder resin 73 and a thermally conductive filler 74 having a thermal conductivity higher than that of the binder resin 73 and blended into the binder resin 73. The thermally conductive filler 74 has, for example, shape anisotropy and is arranged in the wall 72 so that its dimension in the thickness direction is smaller than its dimension in the surface direction. The thermally conductive filler 74 has, for example, electrical insulation properties. The wall 72 is formed, for example, by injection molding as shown in the example of FIG. 4.

[0067] The thickness of the first wall 75 in the thickness direction is 5 mm or less, preferably 3 mm or less, and more preferably 1 mm or less. As shown in the graph of Fig. 6, when the thickness of the first wall 75 is 5 mm or less, the wall 72 including the first wall 75 exhibits a high thermal conductivity (W / mK) in the surface direction. Therefore, the wall 72 including the first wall 75 has reduced temperature unevenness in the surface direction, which makes it possible to uniform the temperature in the storage space 71 inside the thermally insulated container and lengthen the heat retention time.

[0068] As shown in the graph of Fig. 6, the thicker the first wall 75 is, the higher the thermal conductivity (W / mK) in the plane direction of the wall 72 including the first wall 75 is, and the more effectively the temperature is uniformed in the plane direction of the wall 72. However, as shown in the graph of Fig. 7, the thicker the first wall 75 is, the lower the thermal resistivity (m ２As a result, the heat transfer coefficient (K / W) becomes smaller, and heat from outside the insulated container 70 is more likely to be transferred to the storage space 71 in the thickness direction via the wall 72. As described above, a thicker first wall 75 is better for uniform temperature, but the amount of heat transferred from the outside to the wall 72 increases, and the temperature at the corners of the storage space 71 tends to be higher than the temperature at the center, making it easier for temperature variations to occur in the thickness direction of the storage space 71.

[0069] In contrast, as shown in the graph in Figure 8, when the thickness of the first wall 75 is 3 mm or less, the temperature variation in the thickness direction of the storage space 71 is small. This temperature variation is the quotient obtained by subtracting the temperature at the corner from the temperature at the center of the storage space 71 and dividing the temperature difference by the temperature at the center. In this way, when the thickness of the first wall 75 is 3 mm or less, the temperature in the storage space 71 inside the insulated container can be made uniform and the heat retention time can be extended. Furthermore, when the thickness of the first wall 75 is 1 mm or less, the temperature variation is small, so the temperature in the storage space 71 inside the insulated container can be made uniform and the heat retention time can be extended, while reducing costs.

[0070] <Modification 1> In the insulated container 70 of the example in Fig. 5 , the first wall 75 of the wall 72 is laminated on the outer surface of the second wall 76. In contrast, in the insulated container 70 according to Modification 1, as shown in the example in Fig. 9 , the first wall 75 of the wall 72 is laminated on the inner surface of the second wall 76. Note that the first wall 75 of the wall 72 may be laminated on both the inner and outer surfaces of the second wall 76.

[0071] Specifically, as shown in the example of FIG. 9 , the wall 72 includes a first wall 75 having a thermal conductivity c2 in the planar direction greater than a thermal conductivity c1 in the thickness direction, and a second wall 76 made of resin. The first wall 75 is laminated on the inner surface of the second wall 76. The outer surface of the first wall 75 is in contact with the inner surface of the second wall 76, and the first wall 75 and the second wall 76 form a flat plate-shaped wall 72. The outer surface 72o of the wall 72 is formed by the outer surface of the second wall 76, and the inner surface 72i of the wall 72 is formed by the inner surface of the first wall 75. As a result, the second wall 76 and the first wall 75 are cooled by the heat storage material 62, and the temperature is uniformed in the planar direction by the first wall 75. Therefore, the temperature of the storage space 71 surrounded by the first wall 75 is also uniformed, thereby extending the heat retention time.

[0072] 5 and 9 , each of the walls 72, namely, the top wall 72a, the bottom wall 72b, and the side walls 72c to 72f, has a first wall 75 and a second wall 76. In contrast, in the insulated container 70 according to Modification 2, each of the walls 72, namely, the side walls 72c to 72f, has a first wall 75 and a second wall 76. At least one of the walls 72, namely, the top wall 72a and the bottom wall 72b, does not have a first wall 75 but has a second wall 76.

[0073] In the insulated container 70 of the example of FIG. 10 , each of the walls 72 of the side walls 72c to 72f is formed from a second wall 76 and a first wall 75 laminated on the outer surface of the second wall 76. Therefore, the inner surfaces of the side walls 72c to 72f are formed from the inner surface of the second wall 76, and the outer surfaces of the side walls 72c to 72f are formed from the outer surface of the first wall 75. In contrast, each of the walls 72 of the top wall 72a and the bottom wall 72b is formed from the second wall 76. Therefore, the inner surfaces of the top wall 72a and the bottom wall 72b are formed from the inner surface of the second wall 76, and the outer surfaces of the top wall 72a and the bottom wall 72b are formed from the outer surface of the second wall 76. Note that the top wall 72a may be formed from the first wall 75 and the second wall 76. Alternatively, the bottom wall 72b may be formed from the first wall 75 and the second wall 76.

[0074] In the insulated container 70 of the example of FIG. 11 , each wall 72 of the side walls 72c to 72f is formed by a second wall 76 and a first wall 75 laminated on the inner surface of the second wall 76. Therefore, the inner surfaces of the side walls 72c to 72f are formed by the inner surface of the first wall 75, and the outer surfaces of the side walls 72c to 72f are formed by the outer surface of the second wall 76. In contrast, each wall 72 of the top wall 72a and the bottom wall 72b is formed by the second wall 76. Therefore, the inner surfaces of the top wall 72a and the bottom wall 72b are formed by the inner surface of the second wall 76, and the outer surfaces of the top wall 72a and the bottom wall 72b are formed by the outer surface of the second wall 76. Note that the top wall 72a may be formed by the first wall 75 and the second wall 76. Alternatively, the bottom wall 72b may be formed by the first wall 75 and the second wall 76.

[0075] As shown in the examples of Figures 10 and 11, in the insulated container 70, the top wall 72a covers the upper openings of the side walls 72c to 72f in an openable and closable manner. Therefore, when heat from outside the insulated container 70 enters the storage space 71 through the upper opening and the wall 72, the temperature of the top wall 72a side of the storage space 71 tends to be higher than the temperature of the bottom wall 72b side. In contrast, the thermal conductivity of the side walls 72c to 72f located between the top wall 72a and the bottom wall 72b is higher in the planar direction than in the thickness direction. For example, if the top wall 72a and the bottom wall 72b are arranged perpendicular to the vertical direction, the thermal conductivity of the side walls 72c to 72f in the vertical direction is higher. Therefore, heat moves along the side walls 72c to 72f between the top wall 72a and the bottom wall 72b, reducing temperature unevenness in the vertical direction within the storage space 71. This allows for uniform temperature distribution within the storage space 71 and longer heat retention times.

[0076] It should be noted that all of the above embodiments may be combined with one another as long as they do not exclude one another. Furthermore, many improvements and other embodiments of the present invention will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function of the present invention may be substantially changed without departing from the spirit of the present invention.

[0077] The thermal container of the present disclosure can be applied to a thermal container that can achieve uniform temperature in the storage space and long heat retention time.

[0078] 70: Insulated container 71: Storage space 72: Wall 72a: Top wall 72b: Bottom wall 72c: Side wall 72d: Side wall 72e: Side wall 72f: Side wall 72i: Inner surface 72o: Outer surface 73: Binder resin 74: Thermally conductive filler 75: First wall 76: Second wall

Claims

1. A storage space and a wall having an inner surface surrounding the storage space, The heat-retaining container, wherein the wall has a higher thermal conductivity in a plane direction along the inner surface perpendicular to the thickness direction than in a thickness direction perpendicular to the inner surface.

2. The wall has a first wall having a thermal conductivity in the plane direction greater than a thermal conductivity in the thickness direction, The thermal insulation container according to claim 1 , wherein the first wall is formed of a binder resin and a thermally conductive filler having a thermal conductivity higher than a thermal conductivity of the binder resin and mixed into the binder resin.

3. The heat-retaining container according to claim 2 , wherein the thermally conductive filler has shape anisotropy and is arranged such that a dimension in the thickness direction in the wall is smaller than a dimension in the planar direction.

4. The heat-retaining container according to claim 2 or 3, wherein the thermally conductive filler has insulating properties.

5. The wall has a first wall having a thermal conductivity in the plane direction greater than a thermal conductivity in the thickness direction, The heat-retaining container according to claim 1 , wherein a ratio of the thermal conductivity in the thickness direction to the thermal conductivity in the planar direction of the first wall is equal to or greater than 0.2 and less than 0.

8.

6. The wall includes a first wall having a thermal conductivity in the planar direction greater than a thermal conductivity in the thickness direction, and a second wall made of resin, The thermal insulation container according to claim 1 , wherein the first wall is laminated on at least one of an inner surface and an outer surface of the second wall.

7. The thermal insulation container according to claim 6 , wherein the first wall has a thickness of 1 mm or less in the thickness direction.

8. the wall includes a side wall having a pair of openings, a top wall covering one of the pair of openings in an openable and closable manner, and a bottom wall covering the other of the pair of openings, The side wall includes the first wall and the second wall, The thermal insulation container according to claim 6 or 7, wherein at least one of the top wall and the bottom wall does not have the first wall but has the second wall.