Vacuum heat insulating material, method for manufacturing vacuum heat insulating material, and refrigerator

Abstract

Provided are: a vacuum heat insulating material in which the restoring force of a core material having no binder blended therein is kept low so that glass peeling, in which a glass plate peels from a door frame, can be suppressed even when air leakage occurs in the vacuum heat insulating material; a method for manufacturing a vacuum heat insulating material; and a refrigerator.　The vacuum heat insulating material is composed of at least: a laminated core material (75) formed by laminating a plurality of heat-treated unit core materials (71E), each obtained by heat-pressing a flat plate-shaped core material (71D) in which no binder is used; and an outer packaging material (74) accommodating the laminated core material (75) and having an internal space that is decompressed. In this way, since the restoring force of each heat-treated unit core material is kept low, the restoring force of the laminated core material is also consequently kept low, and the occurrence of glass peeling can be suppressed.

Description

Vacuum insulation material, vacuum insulation material manufacturing method, and refrigerator

[0001] The present invention relates to a vacuum insulation material, a method for manufacturing a vacuum insulation material, and a refrigerator.

[0002] In recent refrigerators, glass plates are arranged on the exterior-facing design surfaces of insulated doors such as pivoting doors (double doors) and drawer doors to enhance their design. Furthermore, a vacuum insulation material containing inorganic fibers such as glass fibers is arranged on the back surface of the glass plate as the insulation material provided in the insulated door.

[0003] For example, Japanese Patent Application Laid-Open Publication No. 2020-118404 (Patent Document 1) discloses an insulated door that includes a glass plate on the outer surface, a door frame on the periphery of the glass plate, and a vacuum insulation material placed on the back surface of the glass plate, and the periphery on the back side of the glass plate and the door frame are bonded using hot melt or adhesive tape (double-sided adhesive tape).

[0004] Japanese Patent Application Laid-Open No. 2020-118404

[0005] As described above, in refrigerators such as those described in Patent Document 1, the door frame and the periphery of the glass plate are bonded together with an adhesive such as hot melt or adhesive tape. Furthermore, the vacuum insulation material used does not contain a binder in the core material (inorganic fiber) in order to improve thermal insulation. Adding a binder reduces the thermal insulation performance, so the binder is not added in order to improve thermal insulation.

[0006] Therefore, if the outer packaging of the vacuum insulation panel is damaged or an air leak occurs in the vacuum insulation panel for some reason, the core material (inorganic fiber)'s restoring force (the force that causes the core material to return from its evacuated state to its pre-evacuated state due to the air leak) may push the glass panel out of the door frame, potentially resulting in "glass peeling." In particular, since the core material does not contain a binder, the core material's restoring force is greater (this phenomenon will be explained again in the "Mode for Carrying Out the Invention" section).

[0007] In other words, if the restoring force of the core material of the vacuum insulation panel becomes greater than the adhesive force bonding the glass panel to the door frame, the glass panel may peel off from the door frame. Therefore, from the perspective of product reliability, measures to prevent glass peeling are required.

[0008] An object of the present invention is to provide a vacuum insulation material, a method for manufacturing the vacuum insulation material, and a refrigerator that can suppress glass peeling, in which the glass plate peels off from the door frame, by keeping the restoring force of a core material that does not contain a binder low even if an air leak occurs in the vacuum insulation material.

[0009] The present invention is characterized in that the vacuum insulation material comprises at least a laminated core material formed by stacking multiple sheets of heat-treated unit core material, which is a flat core material made of inorganic fiber without the use of a binder and is subjected to heat and pressure treatment, and an outer packaging material that contains this laminated core material and has a reduced pressure inside space.

[0010] According to the present invention, even if an air leak occurs in the vacuum insulation material, the restoring force of the core material that does not contain a binder can be kept low, thereby preventing glass peeling, in which the glass plate peels off from the door frame.

[0011] FIG. 1 is a top perspective view of a refrigerator. FIG. 2 is a front view of the refrigerator shown in FIG. 1. FIG. 3 is a cross-sectional view showing a cross section in the direction of arrows A-A in FIG. 2. FIG. 4 is an exploded perspective view of a pivotable opening / closing door to which the present invention is applied. FIG. 5 is a cross-sectional view showing a cross section in the direction of arrows B-B in FIG. 4. FIG. 6 is an explanatory diagram illustrating a method for manufacturing a conventional vacuum insulation material. FIG. 7 is an explanatory diagram illustrating glass peeling caused by a conventional vacuum insulation material. FIG. 8 is an explanatory diagram illustrating a method for manufacturing a vacuum insulation material according to an embodiment of the present invention. FIG. 9 is an explanatory diagram illustrating suppression of glass peeling caused by a vacuum insulation material according to an embodiment of the present invention. FIG. 10 is an explanatory diagram illustrating specifications and effects of an embodiment of the present invention and a comparative example. FIG. 11 is an explanatory diagram illustrating the relationship between the restoring forces of a vacuum insulation material according to an embodiment of the present invention and a conventional vacuum insulation material. FIG. 12 is a cross-sectional view showing a first configuration of an insulation door when a vacuum insulation material according to an embodiment of the present invention is attached to a glass plate. FIG. 13 is a cross-sectional view showing a second configuration of an insulation door when a vacuum insulation material according to an embodiment of the present invention is attached to a glass plate.

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope.

[0013] First, the configuration of a refrigerator to which the present invention is applied will be described. Fig. 1 is a perspective view of a refrigerator 100 according to an embodiment of the present invention. Fig. 2 is a front view of the refrigerator 100 shown in Fig. 1.

[0014] As shown in Figures 1 and 2, a refrigerator 100 according to an embodiment of the present invention includes a box body 20 and an insulated door 10 attached to the box body 20. In this embodiment, the insulated door 10 is made up of a plurality of insulated doors 1 to 6. That is, the insulated door 10 is used as a general term for the insulated doors 1 to 6. An outer box 21 includes a top panel 22, a back panel (see Figure 3), a bottom panel (see Figure 3), a left side panel (not shown), and a right side panel 25. The insulated doors 1 and 2 are rotatably supported by hinges 36.

[0015] Fig. 3 is a cross-sectional view showing the A-A cross section of the refrigerator shown in Fig. 2. As shown in Fig. 3, refrigerator 100 has, from top to bottom, a refrigeration compartment 11, an ice-making compartment 12, an upper freezer compartment 13, a lower freezer compartment 14, and a vegetable compartment 15 as storage compartments. Insulated doors 1 to 6 are doors that open and close openings formed in the front of each storage compartment.

[0016] 2 and 3, the insulating doors 1 and 2 are pivotal insulating doors that pivot around hinges 36, and the insulating doors 3 to 6 are drawer-type insulating doors. When the drawer-type insulating doors 3 to 6 are pulled out, the containers that make up each chamber are pulled out together with the insulating door.

[0017] Insulated doors 1 and 2 are insulated doors for refrigerator compartment 11, insulated door 3 is an insulated door for ice-making compartment 12, insulated door 4 is an insulated door for upper freezer compartment 13, insulated door 5 is an insulated door for lower freezer compartment 14, and insulated door 6 is an insulated door for vegetable compartment 15. Each of insulated doors 1 to 6 is provided with a packing 37 (see FIG. 3) for sealing refrigerator 100. The packing 37 is attached to the outer peripheral edge of each of insulated doors 1 to 6 on the interior side.

[0018] 3, each of the insulated doors 1 to 6 has a design surface 31 facing the outside and an inner wall 32 facing the room. In this embodiment, inside each of the insulated doors 1 to 6, i.e., between the design surface 31 and the inner wall 32, a vacuum insulation material 50 is disposed as an insulating material. The vacuum insulation material 50 includes a core material made of inorganic fiber (hereinafter referred to as glass fiber) and an outer wrapping material that covers the core material, and the inside pressure is reduced by vacuuming.

[0019] The space inside each of the insulating doors 1 to 6 other than the vacuum insulating material 50 is filled with a foam insulating material 33 such as rigid urethane foam. The vacuum insulating material 50 will be described in detail later.

[0020] Furthermore, a partition heat insulating wall 16 is provided to separate and insulate the refrigerator compartment 11 from the ice making compartment 12 and the upper freezer compartment 13. Because the temperature zones between the ice making compartment 12, the upper freezer compartment 13, and the lower freezer compartment 14 are the same, a partition member 17 that forms a receiving surface for the packing 37 is provided instead of a partition heat insulating wall.

[0021] A partition heat insulating wall 18 is provided between the lower freezer compartment 14 and the vegetable compartment 15. The arrangement of the storage compartments within the box 20 is not limited to the arrangement described above. Also, with regard to the insulated doors 1 to 6, there are no particular limitations on whether they are opened and closed by rotating or by pulling out, or on the number of divisions of the insulated doors.

[0022] The box 20 comprises an outer box 21 made of steel plate and an inner box 27 made of synthetic resin, and an insulating layer is provided in the space formed by the outer box 21 and the inner box 27 to insulate each storage compartment in the box 20 from the outside. The outer box 21 comprises a top panel 22, a back panel 23, a bottom panel 24, a left side panel (not shown), and a right side panel 25 (see FIG. 1).

[0023] A vacuum insulation material 50 is placed in the space between the outer box 21 and the inner box 27, and the space other than the vacuum insulation material 50 is filled with a foam insulation material 34 such as rigid urethane foam. Furthermore, the partition insulation walls 16, 18 are made of expanded polystyrene 35 and the vacuum insulation material 50, but are not limited to this and may be filled with a foam insulation material such as rigid urethane foam.

[0024] A cooler 44 for cooling each storage compartment of the refrigerator 100 to a predetermined temperature is provided on the back side of the lower freezer compartment 14. This cooler 44, a compressor 45, a condenser 46, and a capillary tube (not shown) are connected to form a refrigeration cycle. A blower 43 is provided above the cooler 44 to circulate the cold air cooled by the cooler 44 inside the refrigerator 100 and maintain the predetermined low temperature.

[0025] A recess 40 for accommodating electrical components 41 such as a board for controlling the operation of the refrigerator 100 and a power supply board is formed in the rear part of the top panel 22 of the box body 20, and a cover 42 for covering the electrical components 41 is provided. The height of the cover 42 is set to be approximately the same height as the top surface of the outer box 21, taking into consideration the external design and ensuring the internal volume.

[0026] Next, the structure between the design surface portion 31 and the vacuum insulation material 50 in the insulated door will be described with reference to Figures 4 and 5. The insulated door shown in Figure 4 is a pivotable insulated door 1 that opens and closes the refrigerator compartment 11. Figure 4 is an exploded perspective view of the pivotable insulated door 1, and Figure 5 is a cross-sectional view of the pivotable insulated door 1.

[0027] In Figure 4, the insulated door 1 is configured to include a rectangular outer panel (hereinafter referred to as glass panel) 60, for example made of glass, provided on the surface of the decorative surface portion 31 of the insulated door 1, door frames 61 provided around the periphery of the glass panel 60 (four in total, on each side), vacuum insulation material 50 arranged on the back surface of the glass panel 60, foam insulation material 33 (see Figure 3) filled into a storage space 62 surrounded on the front and sides by the glass panel 60 and door frame 61, with the vacuum insulation material 50 interposed therebetween, and an inner wall portion 32 provided on the back surface (rear side) of the door frame 61 and covering the rear of the storage space 62.

[0028] The glass plate 60 is formed from a rectangular flat glass plate that forms the outer wall (outer shell, decorative surface) on the front (front) side of the insulated door 1. The outer peripheral edge of the glass plate 60 is attached to the inner front end of a rectangular door frame 61 that extends along the sides of the glass plate 60, and is surrounded by the door frame 61. The glass plate 60 is preferably made of a flat tempered glass material, but flat plastic or ceramic materials may also be used instead of glass. Therefore, in the claims, the term "outer plate" may be used instead of the glass plate.

[0029] The door frame 61 is configured by combining a frame member 63 formed along the right edge of the glass plate 60, a frame member 64 formed along the left edge of the glass plate 60, a frame member 65 formed along the upper edge of the glass plate 60, and a frame member 66 formed along the lower edge of the glass plate 60. The door frame 61 is formed from, for example, ABS (acrylonitrile butadiene styrene copolymer) resin or PP (polypropylene) resin.

[0030] One or more of the frame members 63 to 66, for example, frame member 63, frame member 65, and frame member 66, are formed with engagement grooves 63a, 65a, and 66a that engage with the right edge, upper edge, and lower edge, respectively, of the glass plate 60. These engagement grooves are formed as concave grooves into which the outer peripheral edge of the glass plate 60 is inserted (forming an abutment or covering structure).

[0031] At least one other of the frame members 63 to 66, for example, the frame member 64, is formed with a flange portion (brim portion) 64a that is adhered to the left edge of the glass plate 60 with adhesive tape or hot melt.

[0032] It is also possible to configure one or more or all of the frame members 63, 65, and 66 with the flange portion 64a. In this case, the outer periphery of the glass plate 60 is adhered to the flange portions of the frame members 63, 65, and 66 with adhesive tape or hot melt.

[0033] 5, the frame member 64 is formed with a plate-shaped main body portion 64b extending toward the inner wall portion 32, and a flange portion 64a extending from the main body portion 64b substantially parallel to the surface of the glass plate 10 and substantially perpendicular to the main body portion 64b. The flange portion 64a is located at substantially the end portion on the front side of the frame member 64.

[0034] Furthermore, the main body 64b is formed with reinforcing ribs 64c extending parallel to the flange 64a. The reinforcing ribs 64c have the function of reinforcing the frame member 64 and the function of increasing the adhesion between the frame member 64 and the foam insulation material 33.

[0035] In this embodiment, an example is described in which only one side (the left side), which is at least a part of the four sides of the glass plate 60, is adhered with an adhesive material 67 such as adhesive tape or hot melt, but as mentioned above, it is not limited to one side, and may be two or more sides, or all sides.

[0036] The inner wall portion 32 is a plate member made of resin (ABS resin or the like can be used) provided on the storage compartment side of the insulating door 1. The inner wall portion 32 is also fixed to the peripheral edge portion on the back side of the door frame 61.

[0037] Furthermore, a packing fixing portion 78 is formed on the outer peripheral edge of the inner wall portion 32 on the opposite side of the glass plate 60. A rectangular annular rubber packing is attached to this packing fixing portion 78, and functions to prevent leakage of cold air from the refrigerator compartment.

[0038] Although shown simply by thick lines in FIG. 5, a paint layer 68 is provided on the rear surface of the glass plate 60, and a shatterproof film 69 is provided on the rear surface of the paint layer 68.

[0039] The material of the vacuum insulation material 50 is not particularly limited, but as an example, it is made of an insulation material in which a core material such as glass fiber is vacuum-packed in a laminate film and the inside is reduced in pressure and sealed, and has excellent insulation performance. The vacuum insulation material 50 is formed in a flat plate shape and is adhered to the back side of the glass plate 60.

[0040] The insulated door 1 is configured such that the glass plate 60 and the inner wall portion 32 are spaced apart in the front-to-back direction (front-to-back direction), a vacuum insulation material 50 is placed on the front side of the storage space 62, and foam insulation material 33 is placed in the space excluding the vacuum insulation material 50. The vacuum insulation material 50 is formed to be shorter in the left-to-right direction (width direction) than the glass plate 60, and foam insulation material 33 is also filled between the left end of the vacuum insulation material 50 and the frame member 64.

[0041] The foam insulation material 33 is filled in a storage space 62 formed by a glass plate 60 with a vacuum insulation material 50 placed in the center and a door frame 61 attached to the periphery of the glass plate 60, with the vacuum insulation material 50 interposed therebetween. For example, the foam insulation material 33 is formed by injecting a urethane foam concentrate (raw material liquid of the foam insulation material) into the storage space 62 inside the insulated door 1, foaming it, and then hardening it.

[0042] Next, glass peeling of the glass plate 60 in the heat-insulating door having the above-mentioned configuration will be described.

[0043] The core material of a typical vacuum insulation material 50 is formed by forming a single layer of core material 70 consisting of a flat (sheet-like) layer 71A with a predetermined basis weight to obtain the required thickness, as shown in Figure 6, and then subjecting this to heat-pressure treatment in a heat-pressure treatment device (here, a hot plate press method) 72 to form a heat-treated core material 73 of the vacuum insulation material. The dashed line indicates an outer packaging material 74 that contains the heat-treated core material 73 after vacuuming.

[0044] Here, the heat-treated core material 73 is subjected to a heat-pressure treatment on the entire surface, so that core material regions 71AS, 71AM, and 71AS are formed, each with a different heat treatment state. That is, the core material regions 71AS on the front and back surfaces are heated at a high temperature, and the core material region 71AM near the center is heated at a lower temperature.

[0045] To reduce the restoring force of the heat-treated core material 73 of the vacuum insulation material 50 without using a binder, it is preferable to perform the heat-pressure treatment by adjusting the pressurizing temperature, pressurizing time, and pressurizing pressure so that heat welding occurs in a portion of the core material region 71AM near the center. In this way, heat welding occurs in the glass fibers of the core material region 71AM near the center of the heat-treated core material 73, so that the restoring force can be reduced even if an air leak occurs in the vacuum insulation material 50.

[0046] However, as shown in Figure 6, if a heat-pressure treatment is performed on the entire core material 70 so that heat welding occurs in part of the core material region 71AM near the center, excessive heat welding will occur in the core material region 71AS on the front and back sides, and solid heat conduction will occur from the welded parts between the fibers, significantly reducing the insulation performance.

[0047] Therefore, in reality, to ensure the overall insulating performance of the vacuum insulation material, a heat pressurization process is performed to ensure proper heat sealing in the core material regions 71AS on the front and back sides. However, this creates a new problem: the core material region 71AM near the center is not sufficiently heat sealed, resulting in a large restoring force. In other words, because the front and back sides are heat sealed, the restoring force is suppressed, but because the heat sealing near the center is insufficient, the structure is prone to restoring force.

[0048] Therefore, when such a vacuum heat insulating material 50 is used, peeling of the glass sheet 60 occurs, as shown in FIG.

[0049] 7, before glass peeling occurs, the outer peripheral edge of the glass plate 60 is butted against and adhered to the outer surface of the flange portion 64a formed on the frame member 64 with an adhesive 67 such as adhesive tape. In this state, if an air leak occurs in the vacuum insulation material 50 for some reason, the heat-treated core material 73 of the vacuum insulation material 50 generates a restoring force (FR) in an attempt to return to the state it was in before being evacuated.

[0050] If this restoring force becomes greater than the adhesive force that maintains the glass plate 60 in its current state, the vacuum heat insulating material 50 will push the glass plate 60 outward, causing the glass to peel off.

[0051] In order to prevent glass peeling due to the restoring force generated in the vacuum insulation material due to air leakage, it is necessary to keep the restoring force of the heat-treated core material 73 as small as possible. This embodiment proposes a new vacuum insulation material against this background.

[0052] In this embodiment, the vacuum insulation material is characterized by comprising at least a laminated core material formed by stacking a plurality of heat-treated unit core materials, each of which is a flat core material made of binder-free glass fiber and is subjected to a heat and pressure treatment, and an outer packaging material that contains the laminated core material and has a reduced pressure inside. The configuration of the vacuum insulation material according to this embodiment will be described below.

[0053] As shown in Figure 8, the core material of the vacuum insulation material 50 of this embodiment is formed by subjecting a flat (sheet-shaped) unit core material 71D having a predetermined basis weight to a heat-pressure treatment in a heat-pressure treatment device (here, a hot plate press method) 72 to form a heat-treated unit core material 71E of the vacuum insulation material. The basis weight here is less than that of the core material 70 in Figure 6. Note that, in addition to the hot plate press method, the heat-pressure treatment may also be performed using a hot roller method, as long as a more appropriate heat-pressure treatment is performed.

[0054] Furthermore, because core unit 71D has a low basis weight and is thin, heat is easily transferred quickly to the center of core unit 71D when subjected to heat and pressure treatment. For example, the basis weight of core unit 71D is about one-third of the basis weight of core 70 shown in Figure 6. The basis weight is determined so that the necessary heat welding can be achieved near the center of core unit 71D when subjected to heat and pressure treatment.

[0055] Therefore, heat can easily pass through the core region 71EM near the center between the core regions 71ES on the front and back surfaces of the unit core material 71E in a short time. Therefore, even if a heat-pressure treatment is performed to ensure proper heat welding in the core regions 71ES on the front and back surfaces in order to ensure the insulating performance of the vacuum insulation material, the core region 71EM near the center of the unit core material 71E can also be sufficiently heat-welded.

[0056] The temperature of the core region 71EM near the center of each core unit 71E is controlled to be higher than the distortion temperature so that proper thermal welding can occur. For example, when glass fiber is used as the raw fiber for the core, the distortion temperature for short fiber (C glass) is approximately 500°C, so the temperature is controlled to be higher than this (e.g., 550°C). Also, the distortion temperature for long fiber (E glass) is approximately 550 to 600°C, so the temperature is controlled to be higher than this (e.g., 650°C).

[0057] Then, a plurality of heat-treated unit core materials 71E thus formed (three in this example) are stacked to form a laminated core material 75 consisting of three layers of heat-treated unit core materials 71E, and this laminated core material 75 is then enclosed in an outer packaging material 74. A vacuum is then drawn to encase the laminated core material 75 in the outer packaging material 74, thereby completing the vacuum insulation material 50. The number of heat-treated unit core materials 71E to be stacked can be determined based on the required thickness specification of the vacuum insulation material 50.

[0058] In this way, the core region 71EM near the center of the heat-treated unit core 71E is sufficiently heat-welded. This makes it difficult for a restoring force to be generated, so that even if an air leak occurs, the phenomenon of the glass sheet 60 being pushed out can be suppressed. In addition, the core regions 71ES on the front and back surfaces are subjected to a heat-pressure treatment to ensure proper heat welding, so that sufficient heat insulation performance can be obtained overall.

[0059] 9, the outer peripheral edge of the glass plate 60 is butted against and adhered to the outer surface of the flange portion 64a formed on the frame member 64 with an adhesive 67 such as adhesive tape. In this state, if an air leak occurs in the vacuum insulation material 50 for some reason, the laminated core material 75 of the vacuum insulation material 50 will attempt to restore itself to the state it was in before being evacuated. However, because the core material region 71EM near the center, where a restoring force is likely to occur, is sufficiently heat-welded, the restoring force is unlikely to occur, and the vacuum insulation material 50 is prevented from pushing the glass plate 60 outward.

[0060] Next, a comparison of the specifications and performance of the vacuum heat insulating material shown in Figure 6 and the vacuum heat insulating material shown in Figure 8 will be explained. The raw material is made of short fiber glass fiber.

[0061] First, regarding the core material, the vacuum insulation material of this embodiment (Example 1 and Example 2) is made up of three layers of laminated unit core materials, and the weight of one sheet is 1400 [g / m ２ ], and the total is 4200 [g / m ２ In the vacuum insulation material of this embodiment, the core material is heat pressed layer by layer, and the vacuum insulation material ultimately has three layers. On the other hand, in the conventional vacuum insulation materials (Comparative Examples 1 and 2), the core material is one layer, and the basis weight is 4200 [g / m] as in Examples 1 and 2. ２ ].

[0062] Next, the specifications for the heat press are that the pressing time is 15 minutes in Example 1, 10 minutes in Example 2, 20 minutes in Comparative Example 1, and 20 minutes in Comparative Example 2. The reason for the long pressing time in Comparative Examples 1 and 2 is that the core material 70 is thick, and the temperature near the center is increased.

[0063] Next, the heating temperature was set to the same temperature in each case, taking into consideration the distortion temperature of the glass fiber: 550°C in Example 1, 600°C in Example 2, 550°C in Comparative Example 1, and 600°C in Comparative Example 2, so that the temperatures exceeded the distortion temperatures. Furthermore, the central temperature near the center of the core material after heat pressing was 550°C in Example 1, 550°C in Example 2, 500°C in Comparative Example 1, and 550°C in Comparative Example 2. Here, in Comparative Example 1, the central temperature was 500°C, which did not exceed the distortion temperature, resulting in insufficient heat welding.

[0064] Next, the initial thickness of the core material as the vacuum insulation material is 150 [mm] in Examples 1 and 2, which are laminated in three layers, and is also 150 [mm] in Comparative Examples 1 and 2, which are the same thickness. The basis weight of the core material is 4200 [g / m ２ When using

[0043] , the thickness of the vacuum insulation material obtained is 18 mm, so the thickness after heat pressing is required to be 18 mm.

[0065] On the other hand, after heat pressing (under the same conditions as when air leaks occurred because the laminate was not covered with an exterior material), Examples 1 and 2 were laminated into three layers, resulting in a thickness of 18 mm, while Comparative Example 1 was 25 mm and Comparative Example 2 was 18 mm. In Comparative Example 1, the central temperature was near the distortion temperature, and sufficient heat welding was not performed, resulting in a restoration phenomenon. Therefore, the thickness of Comparative Example 1 did not satisfy the required specifications.

[0066] Next, the thermal conductivity of typical vacuum insulation materials is 2.0 to 3.0 [mW / m·K], with Example 1 having a thermal conductivity of 2.4 [mW / m·K], Example 2 having a thermal conductivity of 2.1 [mW / m·K], Comparative Example 1 having a thermal conductivity of 2.6 [mW / m·K], and Comparative Example 2 having a thermal conductivity of 5.6 [mW / m·K]. In Comparative Example 2, the heating temperature was high and the heating time was long, which caused excessive thermal welding of the glass fibers on the surface of the core material, resulting in a significant deterioration in insulation performance.

[0067] As can be seen, in Examples 1 and 2, when stacked into three layers, both the thickness and thermal conductivity after heat pressing met the requirements. On the other hand, in Comparative Example 1, the heat insulating performance was good and rated "○", but the thickness after heat pressing increased and was rated "×", indicating the occurrence of a restoration phenomenon. Furthermore, in Comparative Example 2, the thickness after pressing was rated "○", but the heat insulating performance was rated "×". This is because the heating temperature was high and the heat molding time was long, causing excessive welding of the glass fibers on the surface, resulting in a deterioration of the heat insulating performance.

[0068] Next, the relationship between the amount of restoration and the restoring force of the vacuum insulation material according to this embodiment and that of a conventional vacuum insulation material will be described. The amount of restoration and the restoring force of the vacuum insulation material when an air leak occurs have the relationship shown in Figure 11. Note that the measurement method in this case was to sandwich the vacuum insulation material in an autograph testing machine, and measure the amount of restoration and the restoring force of the vacuum insulation material when an air leak occurred.

[0069] The measurement method involves first placing the vacuum insulation material in an autograph tester, and then placing acrylic plates above and below it. These acrylic plates are placed to transmit the reaction force to the autograph tester when the vacuum insulation material leaks air. The acrylic plate is 300 mm x 300 mm x 15 mm, and the vacuum insulation material is 250 mm x 500 mm x 12 mm. The reaction force [N] is measured, and the restoring force [MPa] can be calculated from the measured area. Note that the acrylic plate and vacuum insulation material are only examples in this embodiment and are not limited to these.

[0070] Next, the acrylic plate, vacuum insulation material, and acrylic plate are placed in the autograph testing machine, and the pressure is zero when the pressure measurement plate of the autograph testing machine is in contact with the acrylic measurement plate. In this state, the vacuum insulation material's restoring force can be measured by drilling a hole in the vacuum insulation material and allowing air to leak. Furthermore, by raising the measurement height of the autograph testing machine, the restoring force of the vacuum insulation material can be measured depending on the amount of expansion.

[0071] As shown in Figure 11, in conventional vacuum insulation materials, as mentioned above, the heat welding near the center of the heat-treated core material 73 is insufficient to ensure thermal insulation performance, so the more the vacuum insulation material is constrained in the restoration direction, the greater the restoration force. For this reason, as shown in Figure 7, if the restoration force is greater than the adhesive strength of the adhesive material 67, the glass plate 60 will be pulled away from the adhesive material 67, resulting in glass peeling.

[0072] On the other hand, with the vacuum insulation material of this embodiment, the heat insulating performance is ensured and the core material region 71EM near the center of the heat-treated unit core material 75 is sufficiently heat-sealed, so the restoring force does not increase even if the vacuum insulation material is restrained in the restoring direction. Therefore, as shown in Figure 9, the restoring force does not exceed the adhesive force of the adhesive 67, and glass peeling, in which the glass plate 60 is peeled off from the adhesive 67, does not occur.

[0073] Next, a description will be given of the structure for attaching the vacuum insulation material 50 according to the present embodiment to the glass plate 60. In the above-described embodiment, almost the entire surface of the vacuum insulation material 50 was adhered to the back surface of the glass plate 60, but in Figures 12 and 13, a structure is proposed in which the vacuum insulation material 50 and the glass plate 60 are not adhered together, and a space is formed to absorb the expansion of the vacuum insulation material 50. However, a portion of the vacuum insulation material 50 is adhered to the glass plate 60 for positioning purposes.

[0074] 12, the peripheral edge of the glass plate 60 is butted against an inward-facing flange portion 64a formed on a frame body 64. An adhesive material 67 such as adhesive tape is provided between the glass plate 60 and the flange portion 64a, thereby fixing the glass plate 60 to the frame body 64. Here, the vacuum heat insulating material 60 and the flange portion 64a are overlapped and tightly attached.

[0075] The outer edge 50E of the vacuum insulation material 50 is close to the wall surface of the frame 64, which allows for a larger insulating area, contributing to improved insulation. As described above, the heat-treated unit core material 75 prevents the vacuum insulation material from expanding. Therefore, even if the area of ​​the vacuum insulation material 50 is increased, the restoration force in the event of an air leak can be prevented from increasing. By making the repulsive force of the vacuum insulation material 50 smaller than the adhesive force of the adhesive 67, a product can be provided that does not cause glass peeling. Although not shown, by increasing the area of ​​the vacuum insulation material 50, the highly insulating vacuum insulation material 50 can be arranged all the way to the edge of the door. In particular, since the insulation thickness is thinner at the packing fixing portion 99, arranging the vacuum insulation material 50 on the projection of the packing fixing portion 99 can provide a product with high insulating performance.

[0076] Furthermore, a support part forming material (so-called mirror mat) 76, which is made of polyethylene with numerous closed bubbles formed therein, is disposed between the glass plate 60 and the vacuum insulation material 50, thereby forming a space 77 between the vacuum insulation material 50 and the glass plate 60. An adhesive is provided at the portion of the support part forming material 76 that comes into contact with the glass plate 60 and the vacuum insulation material 50, thereby positioning them together.

[0077] The space 77 described above has the function of absorbing the restoring force caused by the expansion, even if an air leak occurs in the vacuum insulation material 50 and the heat-treated unit core material 75 experiences a restoring force, causing the heat-treated unit core material 75 to expand. This further prevents the glass from peeling off.

[0078] 13 shows a modification of the example shown in FIG. 12, in which a passage GP is formed between the flange 64a and the outer edge 50E of the vacuum insulation material 50, and part of the foam insulation material 33 reaches the periphery of the glass plate 60. This creates an adhesive force between the foam insulation material 33 and the glass plate 60, further preventing the glass from peeling off.

[0079] As described above, the present invention is characterized in that the vacuum insulation material comprises at least a laminated core material formed by stacking multiple sheets of heat-treated unit core material, which is a flat core material made of inorganic fiber without the use of a binder and is subjected to heat and pressure treatment, and an outer packaging material that contains this laminated core material and has a reduced pressure inside the space.

[0080] According to this, even if an air leak occurs in the vacuum insulation material, the restoring force of the core material containing no binder can be kept low, thereby preventing the glass sheet from peeling off from the door frame. The present invention is not limited to the above-described embodiments and includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment.

[0081] 50...vacuum insulation material, 60...outer panel (glass plate), 61...frame body, 64...frame member, 64a...flange portion, 67...adhesive, 71D...unit core material, 71E...heat-treated unit core material, 71ES...core material area on the front / back surface of the unit core material, 71EM...core material area near the center of the unit core material, 76...mirror mat, 77...space, 78...gasket fixing portion.

Claims

1. A vacuum insulation material comprising at least a laminated core material formed by stacking a plurality of heat-treated unit core materials obtained by subjecting flat-plate-shaped unit core materials made of binder-free inorganic fibers to a heat-pressure treatment, and an outer packaging material that contains the laminated core materials and has an internal space with a reduced pressure.

2. The vacuum insulation material according to claim 1, wherein the inorganic fibers are glass fibers.

3. A vacuum insulation material according to claim 2, characterized in that the glass fibers are short fibers or long fibers.

4. A vacuum insulation material according to claim 2, characterized in that the heat-treated unit core material is formed from the unit core material which has been heated at a temperature equal to or higher than the distortion temperature of the glass fiber.

5. A refrigerator comprising a refrigerator compartment and / or a freezer compartment, and an insulated door provided in each of the refrigerator compartment and / or the freezer compartment, wherein the insulated door comprises at least an outer panel provided on the outer surface, a door frame provided on the periphery of the outer panel, and a vacuum insulation material arranged on the back surface of the outer panel, the periphery of the back side of the outer panel and part or all of the door frame are bonded using an adhesive, and the vacuum insulation material is the vacuum insulation material described in any one of claims 1 to 4.

6. The refrigerator according to claim 5, wherein the restoring force of the vacuum insulation material when an air leak occurs in the vacuum insulation material is smaller than the adhesive strength of the adhesive that bonds the outer panel and the door frame.

7. The refrigerator according to claim 5, wherein a space is formed between the vacuum insulation material and the outer panel to absorb expansion of the vacuum insulation material when an air leak occurs.

8. The refrigerator according to claim 6, wherein the outer panel is a glass panel made of glass.

9. A method for manufacturing a vacuum insulation material having at least a core material and an outer packaging material containing the core material, the method comprising the steps of: heat-pressurizing a flat unit core material made of binder-free inorganic fibers to form a heat-treated unit core material; stacking a plurality of the heat-treated unit core materials to form a laminated core material; and enclosing the laminated core material in an outer packaging material and reducing the pressure.

10. A method for manufacturing a vacuum insulation material as described in claim 9, characterized in that the inorganic fibers are glass fibers, and the heating temperature in the thermal pressure treatment is a temperature equal to or higher than the distortion temperature of the glass fibers.

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