JP2024093986A - Vacuum insulation material for refrigerators, refrigerators, and method for producing vacuum insulation material for refrigerators - Google Patents

Abstract

The present invention provides a vacuum insulation material for refrigerators that exhibits high insulation performance over a long period of time and has excellent design, a method for manufacturing the same, and a refrigerator with excellent insulation performance.
[Solution] A vacuum insulation material for refrigerators comprises a hollow resin container having at least one opening, a core material filled inside the hollow resin container, a glass layer formed on at least one of the inner and outer surfaces of the hollow resin container, and a sealing portion that seals the opening, wherein the core material is an inorganic powder composition in which carbon powder is dispersed in a low thermal conductivity powder, and the low thermal conductivity powder includes either silica powder or aerogel powder or both.
[Selected figure] Figure 5

Description

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

Vacuum insulation materials have traditionally been used as insulation materials for refrigerators. Vacuum insulation materials are insulation materials in which a core material is filled under reduced pressure inside a hollow resin container. Vacuum insulation materials that use inorganic powders such as aerogel powder as the core material are known (Patent Document 1). Vacuum insulation materials that use a composition containing a fibrous base material such as glass wool and an additive that blocks infrared rays as the core material of the vacuum insulation material are known (Patent Document 2). Carbon, metal oxides, and metals are used as additives that block infrared rays.

JP 2020-106092 A JP 2020-176651 A

To improve the insulating performance of vacuum insulation materials, it is important to suppress the thermal conduction of the core material and the thermal conduction due to radiation. To suppress the thermal conduction due to radiation, it is effective to add an additive with an infrared shielding effect, such as carbon powder, to the core material. However, if the base material of the core material is a fibrous body, the additive tends to become entangled in a solidified state in parts of the fibrous body, and clumps of the additive tend to become scattered throughout the core material. If clumps of the additive are scattered throughout the core material, the effect of suppressing the thermal conduction due to radiation may be insufficient.

In order to improve the insulation performance of a refrigerator, it is effective to increase the coverage rate of the vacuum insulation material with respect to the entire refrigerator box. In order to increase the coverage rate of the vacuum insulation material, it is possible to shape the vacuum insulation material to fit the refrigerator box. The refrigerator box is divided into a freezer, a refrigerator, a vegetable compartment, etc., and has a complex shape. For this reason, if a resin hollow container of the vacuum insulation material is molded into a shape that fits the refrigerator box using blow molding, the thickness of the resulting resin hollow container is likely to be uneven. If the thickness of the resin hollow container of the vacuum insulation material becomes uneven, gas will easily pass through the thinner parts of the resin hollow container, reducing the airtightness of the vacuum insulation material and making it difficult to maintain the insulation performance of the vacuum insulation material for a long period of time. In addition, if the thickness of the resin hollow container becomes uneven, when the inside of the resin hollow container is depressurized with the core material filled, the resin hollow container may be partially deformed due to the pressure difference generated inside the resin hollow container, which may damage the aesthetic appearance of the vacuum insulation material.

The present invention was made in consideration of the above circumstances, and aims to provide a vacuum insulation material for refrigerators that exhibits high insulation performance over a long period of time and has excellent design, a manufacturing method thereof, and a refrigerator that exhibits high insulation performance over a long period of time.

The inventors have found that the above problems can be solved by forming a glass layer on at least one of the inner and outer surfaces of a hollow resin container, and using an inorganic powder composition in which carbon powder is dispersed in a low thermal conductivity powder such as silica powder or aerogel powder as a core material, and have thus completed the present invention. Therefore, the present invention provides the following.

(1) A vacuum insulation material for refrigerators, comprising: a hollow resin container having at least one opening; a core material filled inside the hollow resin container; a glass layer formed on at least one of the inner and outer surfaces of the hollow resin container; and a sealing part for sealing the opening, the core material being an inorganic powder composition in which carbon powder is dispersed in a powder with low thermal conductivity, the powder with low thermal conductivity including either or both of silica powder and aerogel powder.

According to the vacuum insulation material for refrigerators of (1), a glass layer is formed on at least one of the inner and outer surfaces of the hollow resin container, which suppresses the permeation of gas into the interior, and therefore exhibits high insulation performance for a long period of time. In addition, even if the interior of the hollow resin container is depressurized while filled with the inorganic powder composition, the hollow resin container is unlikely to deform, and therefore has excellent design properties. In addition, an inorganic powder composition in which carbon powder with high infrared shielding ability is dispersed in low thermal conductivity powder with low thermal conductivity is used as the core material, so that the thermal conduction of the core material and the thermal conduction due to radiation can be suppressed in a well-balanced manner.

(2) The vacuum insulation material for a refrigerator described in (1) above, in which the glass layer is formed on the outside of the hollow resin container.

(2) Vacuum insulation material for refrigerators makes it easier to form the glass layer, improving productivity.

(3) The vacuum insulation material for refrigerators according to (1) or (2) above, in which the content of the carbon powder in the inorganic powder composition is within the range of 5 to 30 mass %.

According to the vacuum insulation material for refrigerators (3), since the carbon powder content is 5% by mass or more, heat conduction by radiation can be suppressed. On the other hand, since the carbon powder content is 30% by mass or less, there is little contact between carbon particles, which have a higher thermal conductivity than the low thermal conductivity powder. Therefore, when the carbon powder content is within the above range, it is possible to suppress the thermal conduction of the core material and the thermal conduction by radiation in a well-balanced manner.

(4) The low thermal conductivity powder is an aerogel powder, and the packing density of the inorganic powder composition is in the range of 200 to 300 kg / m ^3. The vacuum insulation material for a refrigerator according to any one of (1) to (3).

(4) According to the vacuum insulation material for refrigerators, the low thermal conductivity powder is an aerogel powder, and the packing density of the inorganic powder composition is within the above range, so that the insulation performance is further improved.

(5) The vacuum insulation material for refrigerators according to any one of (1) to (4) above, which has two or more openings, and at least one of the two or more openings is provided with a separation membrane that separates the inorganic powder composition from a gas.

(5) According to the vacuum insulation material for refrigerators, the inside of the vacuum insulation material for refrigerators can be depressurized without allowing the inorganic powder composition to flow out through the opening having the separation membrane.

(6) The vacuum insulation material for a refrigerator described in (5) above, in which the sealing portion that seals the opening having the separation membrane is openable and closable.

(6) According to the vacuum insulation material for refrigerators, the pressure inside the vacuum insulation material for refrigerators can be reduced by opening the sealed portion, so that high insulation performance can be maintained for a longer period of time.

(7) A refrigerator equipped with a vacuum insulation material for a refrigerator described in any one of (1) to (6) above.

The refrigerator (7) is equipped with the above-mentioned vacuum insulation material for refrigerators, and therefore exhibits high insulation performance for a long period of time.

(8) A method for manufacturing a vacuum insulation material for refrigerators, comprising: a preparation step of preparing a resin hollow container with a glass layer, the resin hollow container having at least one opening formed by blow molding, and a glass layer formed on at least one of the inner and outer surfaces of the resin hollow container; an inorganic powder composition filling step of filling the inside of the resin hollow container with an inorganic powder composition in which carbon powder is dispersed in a low thermal conductivity powder, the low thermal conductivity powder including either or both of silica powder and aerogel powder; a vacuum degassing step of degassing the inside of the resin hollow container through the opening of the resin hollow container; and a sealing step of sealing the opening of the resin hollow container.

According to the manufacturing method of vacuum insulation material for refrigerators in (8), a hollow resin container with a glass layer is prepared in the preparation process, so that vacuum insulation material for refrigerators that exhibits high insulation performance over a long period of time and has excellent design properties can be easily manufactured industrially.

The present invention makes it possible to provide a vacuum insulation material for refrigerators that exhibits high insulation performance over a long period of time and has excellent design, a manufacturing method thereof, and a refrigerator with excellent insulation performance.

1 is a front view showing a refrigerator according to an embodiment of the present invention. 2 is a cross-sectional view taken along line II-II of FIG. 1. 1 is a front perspective view showing a vacuum insulation material according to one embodiment of the present invention. 2 is a rear perspective view showing a vacuum insulation material according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of the periphery of a first sealing portion showing a vacuum insulation material according to one embodiment of the present invention. A cross-sectional view of the periphery of a second sealing portion showing a vacuum insulation material according to one embodiment of the present invention. 1 is a cross-sectional view showing one step of a method for producing a vacuum insulation material according to one embodiment of the present invention. 1 is a particle size distribution of the aerogel powder used in Experimental Example 1 of the present invention.

Hereinafter, a vacuum insulation material according to an embodiment of the present invention and a refrigerator using the vacuum insulation material will be described with reference to the accompanying drawings.
1 to 4, the X direction (left-right direction) indicates the width direction of refrigerator 10, the Y direction (front-back direction) indicates the depth direction of refrigerator 10, and the Z direction (up-down direction) indicates the height direction of refrigerator 10. In addition, when describing this embodiment, the same components are generally designated by the same reference numerals, and repeated description will be omitted.

As shown in Figs. 1 and 2, the refrigerator 10 of this embodiment includes insulated doors (upper insulated doors 21a, 21b, middle insulated door 22, and lower insulated door 23) and an insulated box 30. The refrigerator 10 is divided into three sections: an upper section 11, a middle section 12, and a lower section 13. The upper section 11 can be opened and closed by the upper insulated doors 21a, 21b, the middle section 12 by the middle insulated door 22, and the lower section 13 by the lower insulated door 23. The upper insulated doors 21a, 21b are each a rotating door that can rotate left and right from the center around an axis at the end on the side. The middle insulated door 22 and the lower insulated door 23 are each a drawer-type door equipped with a storage container 24.

The insulating box 30 has a vacuum insulating material 40 and a frame 50 that covers the outside of the vacuum insulating material 40. The frame 50 can be made of, for example, a steel plate. As shown in Figures 3 and 4, the vacuum insulating material 40 has a complex shape in which a top surface 40a, a back surface 40b, a bottom surface 40c, side surfaces 40d and 40e, a first partition 40f that separates the upper stage 11 from the middle stage 12, and a second partition 40g that separates the middle stage 12 from the lower stage 13 are integrally molded. A first sealing portion 44a and a second sealing portion 44b are arranged on the back surface 40b of the vacuum insulating material 40.

A machine room 61 is provided between the vacuum insulation material 40 of the lower section 13 and the frame 50. A compressor 62 is housed in the machine room 61. A cooling chamber 63 is defined on the rear side of the middle section 12, and an evaporator 64 is housed in the cooling chamber 63. The evaporator 64 and the compressor 62 are connected to an expansion means and a condenser (not shown) via refrigerant piping to form a vapor compression refrigeration cycle.

A part of the cold air in the cooling chamber 63 cooled by the evaporator 64 is sent to the middle section 12 via the blower 65 and the cold air pipe 66 to cool the middle section 12. The cold air that has cooled the middle section 12 flows into the cooling chamber 63 and is cooled again by the evaporator 64. The remaining cold air is sent to the upper section 11 to cool the upper section 11. The cold air that has cooled the upper section 11 is sent to the lower section 13 via the cold air pipe (not shown), and after cooling the lower section 13, it is sent to the cooling chamber 63 via the cold air pipe (not shown) and is cooled again by the evaporator 64. A damper (not shown) is arranged in the cold air pipe. The control device (not shown) of the refrigerator 10 controls the opening and closing of the damper based on the internal temperature measured by the internal temperature sensor (not shown). This adjusts the flow rate of cold air to keep the internal temperature constant. In this way, the upper section 11, the middle section 12, and the lower section 13 are cooled to a predetermined temperature range. The arrows in FIG. 2 indicate the flow of cold air. In addition, a defrost heater 67 is provided below the evaporator 64 to melt frost on the evaporator 64.

As shown in Figures 5 and 6, the vacuum insulation material 40 has a resin hollow container 41, an inorganic powder composition 42 filled inside the resin hollow container 41, and a glass layer 43 formed on the outer surface of the resin hollow container. The resin hollow container 41 has a first opening 41a shown in Figure 5 and a second opening 41b shown in Figure 6. The first opening 41a is a degassing port used when degassing the resin hollow container 41 and reducing the pressure inside the resin hollow container 41. The second opening 41b is an inorganic powder composition inlet used when filling the resin hollow container 41 with the inorganic powder composition 42. The first opening 41a is sealed with a first sealing portion 44a. The first sealing portion 44a has a first sealing material 45a that can be opened and closed, and a first coating material 46a that covers the first sealing material 45a. The first sealing portion 44a is designed so that the inside of the vacuum insulation material 40 can be decompressed by removing the first coating material 46a and opening the first sealing material 45a. The inside of the first opening 41a is provided with a separation membrane 47 that separates the inorganic powder composition 42 from the gas. There are no particular limitations on the separation membrane 47 as long as it does not allow the inorganic powder composition 42 to pass through and allows the gas to pass through, and for example, a nonwoven fabric, a woven fabric, or a porous membrane can be used. The second opening 41b is sealed with a second sealing portion 44b. The second sealing portion 44b has a second sealing material 45b that cannot be opened or closed, and a second coating material 46b that covers the second sealing material 45b.

The resin hollow container 41 may be, for example, a molded body formed by blow molding. The material of the resin hollow container 41 is not particularly limited, and any thermoplastic resin that can be molded by blow molding may be used. The resin hollow container 41 may be, for example, an olefin resin, an ethylene-vinyl copolymer, a styrene resin, a vinyl resin, a polyamide resin, a polyester resin, a polycarbonate resin, or a polyphenylene oxide resin. Examples of the olefin resin include low-density polyethylene, high-density polyethylene, polypropylene, a cyclic olefin copolymer, and poly(4-methylpentene). Examples of the ethylene-vinyl copolymer include an ethylene-vinyl acetate copolymer, an ethylene-vinyl alcohol copolymer, and an ethylene-vinyl chloride copolymer. Examples of the styrene resin include polystyrene, an acrylonitrile-styrene copolymer, an ABS, and an α-methylstyrene-styrene copolymer. Examples of the vinyl resin include polyvinyl chloride, polyvinylidene chloride, a vinyl chloride-vinylidene chloride copolymer, polymethyl acrylate, and polymethyl methacrylate. Examples of polyamide-based resins include polyamide 6, polyamide 66, polyamide 11, polyamide 12, and polyamide 610. Examples of polyester-based resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.
The thickness of the resin hollow container 41 may be, for example, within the range of 0.4 mm or more and 2.0 mm or less.

The inorganic powder composition 42 is a composition in which carbon powder 42b is dispersed in low thermal conductivity powder 42a. The content of low thermal conductivity powder 42a in the inorganic powder composition 42 is preferably greater than the content of carbon powder 42b. The content of carbon powder 42b in the inorganic powder composition 42 is not particularly limited, but may be within the range of 5 to 30 mass%. If the carbon powder content is 5 mass% or more, heat conduction by radiation can be suppressed. On the other hand, if the carbon powder content is 30 mass% or less, there is less contact between carbon particles, which have a higher thermal conductivity than the aerogel particles. Therefore, if the carbon powder content is within the above range, the heat conduction of the core material and the heat conduction by radiation can be suppressed in a balanced manner.

The low thermal conductivity powder 42a includes either or both of silica powder and aerogel powder. The low thermal conductivity powder 42a may be a single silica powder or aerogel powder, or may be a powder mixture of silica powder and aerogel powder. The silica powder may be wet silica powder or dry silica powder. As the aerogel powder, silica aerogel powder can be used. As the carbon powder 42b, for example, carbon black, acetylene black, ketjen black, furnace black, natural graphite, artificial graphite, amorphous carbon, activated carbon, hard carbon, soft carbon, carbon nanofiber, and carbon nanotube can be used.

The particle shape of the low thermal conductivity powder 42a and the carbon powder 42b is not particularly limited and may be spherical. If the particle shape of the low thermal conductivity powder 42a and the carbon powder 42b is spherical, the contact between the particles will be point contact, and the thermal conductivity between the particles will be low. This improves the thermal insulation performance of the vacuum insulation material 40.

The median diameter (DA50) of the low thermal conductivity powder 42a may be, for example, in the range of 1 to 400 μm, preferably in the range of 1 to 200 μm, and more preferably in the range of 1 to 100 μm. When the median diameter (DA50) of the low thermal conductivity powder 42a is within the above range, the thermal conduction of the core material can be further suppressed. In addition, the fluidity of the inorganic powder composition 42 is increased, making it easier to fill the interior of the resin hollow container 41 uniformly.

The median diameter (DC50) of the carbon powder 42b may be in the range of 0.0050 to 0.50 as the ratio (DC50/DA50) of the median diameter (DC50) of the carbon powder 42b to the median diameter (DA50) of the low thermal conductivity powder 42a. When DC50/DA50 is 0.50 or less, the carbon particles are easily dispersed between the aerogel particles, and not only the heat conduction by radiation but also the heat conduction of the core material can be suppressed. On the other hand, when DC50/DA50 is 0.0050 or more, the carbon particles are less likely to aggregate between the aerogel particles. From the viewpoint of suppressing the aggregation of the carbon particles, DC50/DA50 may be in the range of 0.050 to 0.50.

In the frequency distribution curve of the undersieve, the low thermal conductivity powder 42a may have a ratio (D90/D10) of the particle size at which the cumulative value of the passing portion is 90% (D90) to the particle size at which the cumulative value of the passing portion is 10% (D10) in the range of 2 to 20, or may have a ratio of 2 to 10. The low thermal conductivity powder 42a with D90/D10 in the above range has a narrow particle size distribution and high fluidity. Therefore, the inorganic powder composition 42 containing this low thermal conductivity powder 42a has a high filling density in the resin hollow container 41. The carbon powder 42b's D90/D10 may be in the range of 2 to 20, or may have a ratio of 2 to 10. The carbon powder 42b with D90/D10 in the above range has a narrow particle size distribution and high fluidity. Therefore, the inorganic powder composition 42 containing this carbon powder 42b has the carbon powder 42b uniformly dispersed, and the composition has a high uniformity. The median diameters (D50), D10, and D90 of the low thermal conductivity powder 42a and carbon powder 42b are values measured by a laser diffraction scattering method.

The packing density of the inorganic powder composition 42 of the vacuum insulation material 40 may be within a range of 200 to 300 kg/ ^m3 , for example, when the low thermal conductivity powder 42a is an aerogel powder. When the packing density of the inorganic powder composition 42 is within the above range, the heat insulating performance is further improved.

The glass layer 43 has the function of suppressing the permeation of gas into the inside of the vacuum insulation material 40 and making the hollow resin container 41 less likely to deform.
The thickness of the glass layer 43 may be, for example, in the range of 3 mm or less.

The first sealing material 45a may be any material that can be opened and closed, and a known valve may be used. The material of the second sealing portion 44b is preferably one that has low gas permeability. The material of the second sealing portion 44b may be glass or resin. The material of the first coating material 46a and the second coating material 46b may be, for example, glass.

According to the vacuum insulation material 40 of this embodiment configured as described above, the inorganic powder composition 42 in which carbon powder 42b with high infrared shielding ability is dispersed in low thermal conductivity powder 42a with low thermal conductivity is used as the core material, so that the thermal conduction of the core material and the thermal conduction due to radiation can be suppressed in a well-balanced manner. In addition, the inorganic powder composition 42 has high fluidity and is easy to fill the inside of hollow resin containers 41 of various shapes. Therefore, the vacuum insulation material 40 of this embodiment exhibits high thermal insulation performance and is easy to form into complex shapes.

In addition, the vacuum insulation material 40 of this embodiment has a glass layer 43 formed on the outer surface of the hollow resin container 41, which suppresses the permeation of gas into the interior, and therefore exhibits high insulation performance over a long period of time. Furthermore, even if the interior of the hollow resin container 41 is depressurized while filled with the inorganic powder composition 42, the hollow resin container 41 is unlikely to deform, so wrinkles are unlikely to occur on the surface, and the design is excellent. Furthermore, the glass layer 43 is formed on the outer surface of the hollow resin container 41, which makes it easy to form the glass layer 43, improving productivity.

In the vacuum insulation material 40 of this embodiment, the first opening 41a is sealed with an openable first sealing material 45a, and the inside of the vacuum insulation material 40 can be depressurized by opening the first sealing material 45a. Therefore, if the internal pressure of the vacuum insulation material 40 increases, the inside of the vacuum insulation material 40 can be depressurized again, thereby maintaining high insulation performance for a longer period of time.

The refrigerator 10 of this embodiment has a high insulation performance over a long period of time because the insulated box 30 has vacuum insulation material 40. In addition, because the vacuum insulation material 40 has a high designability, there is no particular need to cover the inside of the vacuum insulation material 40 with a decorative panel. By not covering it with a decorative panel, the capacity of the insulated box 30 can be increased.

Next, a method for manufacturing a vacuum insulation material according to an embodiment of the present invention will be described using the above-mentioned vacuum insulation material 40 as an example.
The vacuum insulation material 40 can be manufactured by a method including, for example, a preparation step, an inorganic powder composition filling step, a vacuum deaeration step, and a sealing step.

The preparation step is a step of preparing a resin hollow container 41 with a glass layer 43, which has a resin hollow container 41 having a first opening 41a and a second opening 41b, and a glass layer 43 formed on the outer surface of the resin hollow container 41. The resin hollow container 41 is produced by blow molding. The resin hollow container 41 can be produced by blow molding, for example, by pouring molten thermoplastic resin into a blow molding die and blowing air into the thermoplastic resin from the inside to mold the thermoplastic resin into the shape of the die. As a method for forming the glass layer 43 on the outer surface of the resin hollow container 41, for example, a method of removing the resin hollow container 41 from the die and attaching a glass film to the outer surface of the removed resin hollow container 41 can be used.

The first opening 41a and the second opening 41b may be formed when the resin hollow container 41 is produced by blow molding, or may be formed on the resin hollow container 41 after the glass layer 43 is formed. A separation membrane 47 may be placed on the inside of the first opening 41a before the inorganic powder composition filling step.

The inorganic powder composition filling process is a process of filling the inside of the resin hollow container 41 with the inorganic powder composition 42 through the second opening 41b. The inorganic powder composition 42 can be obtained by weighing and mixing the low thermal conductivity powder 42a and the carbon powder 42b. There is no particular limit to the mixing method, and they may be mixed in a dry manner or a wet manner. There is no particular limit to the filling method of the inorganic powder composition 42, and a known method can be used. After the inorganic powder composition filling process is completed, the second sealing material 45b is inserted into the second opening 41b, and then the second sealing material 45b is covered with the second coating material 46b to seal the second opening 41b.

The vacuum degassing step is a step of degassing the inside of the resin hollow container 41 filled with the inorganic powder composition 42 through the first opening 41 a of the resin hollow container 41 .
The vacuum degassing process may be performed by inserting a first sealant 45a into the first opening 41a, opening the first sealant 45a, and degassing the inside of the hollow resin container 41 using a vacuum pump 72, as shown in FIG. 7 .

The sealing process is a process of sealing the first opening 41a. In the sealing process, the first sealing material 45a inserted into the first opening 41a may be closed, and then the first sealing material 45a may be covered with the first coating material 46a to seal the first opening 41a.

The above steps result in the manufacture of the vacuum insulation material 40. According to the manufacturing method of the vacuum insulation material 40 of this embodiment, a hollow resin container 41 with a glass layer 43 is prepared in the preparation step, so that vacuum insulation material for refrigerators that exhibits high insulation performance over a long period of time and has excellent design properties can be easily manufactured industrially.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment.
For example, in the vacuum insulation material 40 of the present embodiment, the glass layer 43 is formed on the outer surface of the hollow resin container 41, but the present invention is not limited to this. The glass layer 43 may be formed on the inner surface of the hollow resin container 41, or may be formed on both the inner and outer surfaces of the hollow resin container 41. The hollow resin container 41 having the glass layer 43 formed on the inner surface can be obtained by forming a resin layer on the outside of the hollow glass container.

In addition, in the vacuum insulation material 40 of this embodiment, the first opening 41a is a deaeration port and the second opening 41b is an inorganic powder composition inlet, but the present invention is not limited to this. One opening may be both a deaeration port and an inorganic powder composition inlet. In this case, the resin hollow container 41 is filled with the inorganic powder composition 42, and then a separation membrane 47 is placed in the opening, after which the pressure inside the resin hollow container 41 is reduced and the opening is sealed.

In addition, in the vacuum insulation material 40 of this embodiment, the first opening 41a is sealed with the first sealing material 45a that can be opened and closed, and the second opening 41b is sealed with the second sealing material 45b that cannot be opened and closed, but the present invention is not limited to this. Both the first opening 41a and the second opening 41b may be sealed with the first sealing material 45a that can be opened and closed, or may be sealed with the second sealing material 45b that cannot be opened and closed.

In the refrigerator 10 of this embodiment, the inside of the vacuum insulation material 40 is not covered with a decorative panel, but the present invention is not limited to this. The inside of the vacuum insulation material 40 may be covered with a decorative panel. Also, in the refrigerator 10 of this embodiment, the vacuum insulation material 40 may be used as the insulation material for the insulated doors (upper insulated doors 21a, 21b, middle insulated door 22, and lower insulated door 23).

[Experimental Example]
(Experimental Example 1)
Silica aerogel powder (manufactured by Guangdong Alison Hi-tech Co., Ltd.) having a median diameter (DA50) of 20.2 μm and carbon powder (manufactured by Toyo Tanso Co., Ltd.) having a median diameter (DC50) of 2.0 μm were prepared. The silica aerogel powder and the carbon powder were dry-mixed in a mass ratio of 90:10 to obtain an inorganic powder composition having a carbon powder content of 10 mass%.

The obtained inorganic powder composition was placed in an aluminum vapor deposition bag (size: 300 mm x 200 mm, manufactured by Dai Nippon Printing Co., Ltd.). Next, the pressure inside the bag-shaped container was reduced using a vacuum pump, and the opening of the bag-shaped container was sealed to produce a vacuum insulation material (size: 200 mm x 200 mm x 15 mm thick).

Comparative Experimental Example 1
A vacuum insulation material was produced in the same manner as in Example 1, except that a silica aerogel powder having a median diameter (DA50) of 20.2 μm was used alone instead of the inorganic powder composition.

(Experimental Example 2)
An inorganic powder composition was obtained in the same manner as in Experimental Example 1, except that a silica aerogel powder having a median diameter (DA50) of 300 μm (manufactured by Guangdong Alison Hi-tech Co., LTD.) was used instead of the silica aerogel powder having a median diameter (DA50) of 20.2 μm. A vacuum insulation material was produced in the same manner as in Experimental Example 1 using the obtained inorganic powder composition.

Comparative Experimental Example 2
A vacuum insulation material was produced in the same manner as in Experimental Example 1, except that a silica aerogel powder having a median diameter (DA50) of 300 μm was used alone instead of the inorganic powder composition.

(evaluation)
The packing density and thermal conductivity of the inorganic powder composition were measured by the following methods for the vacuum insulation materials obtained in Experimental Examples 1 and 2 and Comparative Experimental Examples 1 and 2. The results are shown in Table 1 below.

(Packing density of inorganic powder composition)
The measurement was performed according to a method in accordance with JIS K 7222:2005 "Foamed plastics and rubber - Determination of apparent density."

(Thermal conductivity)
The measurements were performed at an average specimen temperature of 24° C. using a method in accordance with JIS A 1412-2:1999 “Method of measuring thermal resistance and thermal conductivity of thermal insulation materials - Part 2: Heat flow meter method (HFM method)”.

The vacuum insulation materials of Experimental Examples 1 and 2 contain carbon powder with high infrared shielding ability as the inorganic powder composition, which is the core material, and therefore have less heat conduction due to radiation than the vacuum insulation materials of Comparative Examples 1 and 2, which use silica aerogel powder alone as the core material. In addition, the results shown in Table 1 show that the vacuum insulation material of Experimental Example 1 has a lower thermal conductivity measured by the HFM method than the vacuum insulation material of Comparative Experimental Example 1, and the vacuum insulation material of Experimental Example 2 has a lower thermal conductivity of the core material than the vacuum insulation material of Comparative Experimental Example 2. This is thought to be because the thermal conductivity between the silica aerogel powder is reduced by the carbon particles being dispersed between the silica aerogel particles.

The vacuum insulation material of Experimental Example 1 has a higher packing density of the inorganic powder composition than the vacuum insulation material of Experimental Example 2. This is thought to be because the silica aerogel powder used in the vacuum insulation material of Experimental Example 1 has a narrow particle size distribution range and a low D90/D10 of 4.1, as shown in Figure 8.

REFRIGERATION LIST 10 Refrigerator 11 Upper section 12 Middle section 13 Lower section 21a, 21b Upper insulated door 22 Middle insulated door 23 Lower insulated door 24 Storage container 30 Insulated box body 40 Vacuum insulated material 41 Hollow container 41a First opening 41b Second opening 42 Inorganic powder composition 42a Low thermal conductivity powder 42b Carbon powder 43 Glass layer 44a First sealing portion 44b Second sealing portion 45a First sealing material 45b Second sealing material 46a First coating material 46b Second coating material 47 Separation membrane 50 Frame 61 Machine room 62 Compressor 63 Cooling chamber 64 Evaporator 65 Blower 66 Cold air piping 67 Defrosting heater 70 Chamber 71 Temporary lid material 72 Vacuum pump

Claims (8)

The present invention relates to a hollow resin container having at least one opening, a core material filled in the hollow resin container, a glass layer formed on at least one of the inner and outer surfaces of the hollow resin container, and a sealing part that seals the opening,
The core material is an inorganic powder composition in which carbon powder is dispersed in a low thermal conductivity powder,
The vacuum insulation material for a refrigerator, wherein the low thermal conductivity powder contains either or both of a silica powder and an aerogel powder. The vacuum insulation material for refrigerators according to claim 1, wherein the glass layer is formed on the outside of the hollow resin container. The vacuum insulation material for refrigerators according to claim 1, wherein the content of the carbon powder in the inorganic powder composition is within the range of 5 to 30 mass %. The vacuum insulation material for refrigerators according to claim 1, wherein the low thermal conductivity powder is an aerogel powder, and the packing density of the inorganic powder composition is in the range of 200 to 300 kg/ ^m3 . The vacuum insulation material for refrigerators according to claim 1, which has two or more openings, and at least one of the two or more openings is provided with a separation membrane that separates the inorganic powder composition from a gas. The vacuum insulation material for refrigerators according to claim 5, wherein the sealing portion that seals the opening that includes the separation membrane is openable and closable. A refrigerator equipped with a vacuum insulation material for refrigerators according to any one of claims 1 to 6. A preparation step of preparing a resin hollow container with a glass layer, the resin hollow container having at least one opening formed by blow molding and a glass layer formed on at least one of the inner and outer surfaces of the resin hollow container;
An inorganic powder composition filling step of filling the inside of the resin hollow container with an inorganic powder composition in which carbon powder is dispersed in a low thermal conductivity powder, the low thermal conductivity powder including either or both of silica powder and aerogel powder;
a vacuum degassing step of degassing the inside of the resin hollow container through the opening of the resin hollow container;
and a sealing step of sealing the opening of the resin hollow container.

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