AU2017424996A1

AU2017424996A1 - Vacuum insulation material, heat insulation box, and method for producing vacuum insulation material

Info

Publication number: AU2017424996A1
Application number: AU2017424996A
Authority: AU
Inventors: Shohei ABIKO; Kazumasa Fujimura; Takayoshi MUKAIYAMA; Yuki OMORI; Hiroaki Takai
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-07-25
Filing date: 2017-07-25
Publication date: 2019-12-19
Anticipated expiration: 2037-07-25
Also published as: WO2019021359A1; TWI659177B; CN110892187B; AU2017424996B2; TW201908640A; JP7129979B2; CN110892187A; JPWO2019021359A1

Abstract

This vacuum heat insulation material comprises a core material that holds a vacuous space, a hydroxide, and an outer covering material that covers the core material and the hydroxide, the interior of the outer covering material being depressurized and sealed, and the weight of the hydroxide being at least 0.01 times the weight of the core material. This method for manufacturing a vacuum heat insulation material comprises: a step for using the outer covering material to cover and seal an oxide and the core material for holding the vacuous space, thus forming a sealed body; a step for heat-treating the sealed body; and a step for depressurizing and sealing the interior of the outer covering material of the sealed body.

Description

656600 KPO-3512 DESCRIPTION

Title of Invention

VACUUM INSULATION MATERIAL, HEAT INSULATION BOX, AND METHOD FOR PRODUCING VACUUM INSULATION MATERIAL

Technical Field [0001]

The present invention relates to a vacuum insulation material used as a heat insulating material for use in refrigerators and other apparatuses, a heat insulation box, and a method for producing the vacuum insulation material.

Background Art [0002]

Generally, in existing vacuum insulation materials, a core and an adsorbent that adsorbs moisture or gas are coated with an enveloping material, and the pressure of the inside of the enveloping material is reduced to a pressure close to a vacuum level, whereby the enveloping material is sealed (see, for example, Patent Literature 1). In such a vacuum insulation material, if the degree of vacuum in the enveloping material is reduced, the heat insulation performance of the vacuum insulation material is also reduced. In view of this point, in the vacuum insulation material of Patent Literature 1, the core is dried in a drying furnace before inserted into the enveloping material. This process reduces the amount of the moisture released from the core after the internal pressure of the enveloping material is reduced and the enveloping material is sealed, to thereby increase the degree of vacuum in the enveloping material and reduce the deterioration of the heat insulation performance.

Citation List

Patent Literature [0003]

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2004-286050

Summary of Invention Technical Problem

656600 KPO-3512 [0004]

According to Patent Literature 1, the core is dried before inserted into the enveloping material, and then amount of moisture removed from the core by a drying process in the drying furnace depends on relative humidity in the drying furnace. The relative humidity in the drying furnace varies in accordance with the season, weather, and other conditions, and thus the amount of moisture removed from the core also varies. Therefore, after the internal pressure of the enveloping material containing the core inserted therein is reduced and the enveloping material is sealed, the amount of moisture released from the core into the enveloping material also varies. As a result, the degree of vacuum in the enveloping material varies in accordance with the season, weather, and other conditions. Inevitably, the variance between the heat insulation performances of vacuum insulation materials is great.

[0005]

The present invention has been made to solve the above problem, and an object of the invention is to provide a vacuum insulation material and a heat insulation box that have a heat insulation performance that does not greatly vary from that of each of other produced heat insulation materials or that of each of other produced heat insulation boxes, and a method for producing the vacuum insulation material.

Solution to Problem [0006]

A vacuum insulation material according to an embodiment of the present invention includes: a core that maintains a vacuum space; hydroxide; and an enveloping material that covers the core and hydroxide. The internal pressure of the enveloping material is reduced and the enveloping material is sealed. The weight of hydroxide is 0.01 times or more that of the core.

[0007]

A heat insulation box according to another embodiment of the present invention includes the vacuum insulation material.

[0008]

A method for producing a vacuum insulation material, according to still another

656600 KPO-3512 embodiment of the present invention, includes the steps of: coating a core that maintain a vacuum space and hydroxide with an enveloping material and sealing the enveloping material, thereby forming a sealed body; performing heat treatment on the sealed body; and reducing the internal pressure of the enveloping material of the sealed body to seal the enveloping material.

Advantageous Effects of Invention [0009]

According to the embodiments of the present invention, since the weight of the hydroxide in the enveloping material is 0.01 times or more that of the core therein, it is possible to obtain a vacuum insulation material and a heat insulation box, which have a heat insulation performance that does not greatly vary from that of each of other vacuum insulation materials or that of each of other heat insulation boxes. Also, since the core is subjected to the heat treatment after coated with the enveloping material, the core can be uniformly dried without depending on relative humidity of a heat treatment furnace and it is possible to provide a method for producing a vacuum insulation material having a heat insulation performance that does not greatly vary from that of each of other produced vacuum insulation materials.

Brief Description of Drawings [0010] [Fig. 1] Fig. 1 is a sectional view illustrating a schematic configuration of a vacuum insulation material according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a production flow chart of the vacuum insulation material according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a sectional view illustrating a schematic configuration of the vacuum insulation material including an adsorbent 3 added thereto in step S21 in a production process indicated in Fig. 2.

[Fig. 4] Fig. 4 is a diagram illustrating a relationship between the thermal conductivity and the ratio of the weight of calcium hydroxide to that of a core under conditions of Example 3 regarding the vacuum insulation material according to Embodiment 1 of the present invention.

656600

KPO-3512 [Fig. 5] Fig. 5 is a sectional view illustrating a schematic configuration of a heat insulation box according to Embodiment 2 of the present invention.

Description of Embodiments [0011]

Embodiment 1

A vacuum insulation material according to Embodiment 1 of the present invention and a producing method of the vacuum insulation material will be described.

[0012]

Fig. 1 is a sectional view illustrating a schematic configuration of the vacuum insulation material according to Embodiment 1 of the present invention. It should be noted that in the figures including Fig. 1 which will be referred to, the relationship between the sizes of components and the shapes of components may be different from actual ones. Specific sizes of the components should be considered based on the following description.

As illustrated in Fig. 1, the vacuum insulation material 1 includes a core 2, an adsorbent 3, hydroxide 4, and an enveloping material 5 that covers these elements. The enveloping material 5 is sealed such that the pressure of the internal space of the enveloping material 5 is reduced to a vacuum level of approximately 1 to 3 Pa. The vacuum insulation material 1 is formed in the shape of a substantially rectangular plate as a whole.

[0013]

The core 2 is used for the purpose of maintaining a vacuum space. As the core 2, a fiber assembly such as glass wool is used. Also, the fiber assembly forming the core 2 may be obtained by heat press forming or by hermetic sealing using an inner packing material or by binding using a binding agent.

[0014]

The adsorbent 3 adsorbs gas or moisture in the vacuum insulation material 1. The adsorbent 3 is used for the purpose of adsorbing gas or moisture in the vacuum insulation material 1 and thereby maintaining the degree of vacuum in the vacuum insulation material 1. By maintaining the degree of vacuum in the vacuum insulation

656600 KPO-3512 material 1, it is possible to reduce the increase of the thermal conductivity, i.e., reduces the deterioration of the heat insulation performance. As the adsorbent 3, for example, calcium oxide (CaO) is used. The adsorbent 3 may be silica gel, zeolite, or a combination thereof.

[0015]

As the enveloping material 5, an enveloping material used in existing vacuum insulation materials can be used. The enveloping material 5 is a laminate film having a multilayer structure. In the multilayer structure, for example, a polyethylene layer, an aluminum-deposited ethylene vinyl alcohol layer, an aluminum-deposited polyethylene terephthalate layer, and a nylon layer are stacked in this order from a core side where the core 2 is located, and the nylon layer is thus an outermost layer. It should be noted that the enveloping material 5 is not limited to the above configuration, and alumina vapor deposition or silica vapor deposition may be used instead of the aluminum deposition. It is sufficient that the enveloping material 5 has gas barrier properties. [0016]

The hydroxide 4 holds moisture released from the core 2 by heat treatment, which will be described later. The weight of the hydroxide 4 is 0.01 times or more the weight of the adsorbent 3 and core 2. As the hydroxide 4, for example, calcium hydroxide (Ca(OH)2) is used. Also, the hydroxide 4 may be magnesium hydroxide, aluminum hydroxide, or a combination thereof.

[0017]

Next, a production process of the vacuum insulation material 1 according to Embodiment 1 will be described.

[0018]

Fig. 2 is a production flow chart of the vacuum insulation material according to Embodiment 1 of the present invention.

In the production process of the vacuum insulation material 1 according to Embodiment 1, first, the core 2, the adsorbent 3, and oxide are coated with the enveloping material 5, and the enveloping material 5 is sealed (step S11), thereby forming a sealed body 5. The oxide is, for example, calcium oxide. Then, the sealed

656600

KPO-3512 body is subjected to heat treatment (step S12). As the conditions for the heat treatment, for example, the temperature and time at and for which the heat treatment is carried out are 100 degrees C and 2 hours. The condition or conditions for the heat treatment may be any conditions as long as moisture is released from the core 2 by the heat treatment carried out under the conditions.

[0019]

As the result of the heat treatment, the hydroxide 4 is formed by a chemical reaction between the moisture released from the core 2 and the oxide. That is, the moisture released from the core 2 is held by the hydroxide 4. The formed hydroxide 4 is, for example, calcium hydroxide.

[0020]

Next, part of the enveloping material 5 is opened (step S13). Then, the internal pressure of the enveloping material 5 the part of which is opened is reduced, and the enveloping material 5 is then sealed (step S14). To be more specific, the internal pressure of the enveloping material 5 is reduced to a vacuum level of approximately 1 to 3 Pa, and the opened part is, for example, heat-sealed, thereby sealing the enveloping material 5.

[0021]

It should be noted that although in step S11, the adsorbent 3 is coated with the enveloping material 5, a step of adding another adsorbent 3 in the enveloping material 5 (step S21) may be provided between step S13 and step S14. Also, it should be noted that Fig. 3 illustrates a configuration in which the other adsorbent 3 is added.

[0022]

Fig. 3 is a sectional view illustrating a schematic configuration of the vacuum insulation material including the other adsorbent added thereto in step S21 in the production process indicated in Fig. 2.

As illustrated in Fig. 3, in the case of adding an adsorbent 3a in addition to the adsorbent 3, the adsorbent 3a can be provided in a region other than a region in which the hydroxide 4 is provided. In such a manner, in the case where the adsorbent 3a is provided in the region other than the region in which the hydroxide 4 is provided, it is

656600

KPO-3512 possible to prevent the enveloping material 5 from being damaged from inside, without bulking the enveloping material 5. It should be noted that the adsorbent 3 corresponds to a first adsorbent of the present invention, and the adsorbent 3a corresponds to a second adsorbent of the present invention.

[0023]

In the above process, the core 2 is subjected to the heat treatment after coated with the enveloping material 5. Thus, the core 2 can be uniformly dried without depending on the relative humidity of a heat treatment furnace. Therefore, after a pressure-reduction and sealing process for the inside of the enveloping material 5 in step S14, the amount of moisture released from the core 2 does not vary in accordance with the season and weather. As a result, the variance between the degrees of vacuum in enveloping materials 5 of vacuum insulation materials 1 is small, and the variance between the thermal conductivities of the vacuum insulation materials 1, that is, the heat insulation performances thereof, is also small.

[0024]

It should be noted that vacuum insulation materials 1 were produced according to Embodiment 1, and Examples 1 to 3 were compared with Comparative Examples 1 to

3. The result of the above comparison will be described as follows.

[0025] <Example 1>

In Example 1, the variance between the thermal conductivities of the vacuum insulation materials 1 was examined. The sample and conditions of Example 1 were as indicated in items (1) to (5) below.

(1) Core 2: glass wool that is 5 kg in weight (2) Enveloping material 5: a laminate film having a multilayer structure in which a polyethylene layer, an aluminum-deposited ethylene vinyl alcohol layer, an aluminumdeposited polyethylene terephthalate layer, and a nylon layer were stacked in this order, and the nylon layer was thus the outermost layer (3) Adsorbent 3: 100 g of calcium oxide (4) Heat treatment: at 100 degrees C for 2 hours

656600 KPO-3512 (5) Pressure-reduction process: reduction to a vacuum level of approximately 1 to 3 Pa [0026]

Under the above conditions, ten vacuum insulation materials 1 were produced in the production process indicated in Fig. 2. It should be noted that step S11 indicated in Fig. 2 is a step of coating the core 2, the adsorbent 3 and an oxide with the enveloping material 5, and sealing the enveloping material 5; and the adsorbent 3 was calcium oxide, which is indicated in item (3) above, that is, it was an oxide. Thus, after all, step S11 is a step of coating the core 2 and the oxide indicated in item (3) with the enveloping material 5, and sealing the enveloping material 5. Also, “addition of adsorbent” in step S21 was not carried out. Then, after measuring the thermal conductivity of each of the vacuum insulation materials 1, each vacuum insulation material 1 was opened, and the weight of calcium hydroxide, which was the hydroxide 4, was measured.

[0027]

In Comparative Example 1, the same sample and conditions as indicated in items (1) to (5) above regarding Example 1 were applied. In Comparative Example 1, the heat treatment was carried out under the condition indicated in item (4) without sealing the enveloping material 5 after coating the core 2 with the enveloping material 5. Next, the adsorbent 3 was provided in the enveloping material 5 and the enveloping material 5 was sealed.

[0028]

In the above manner in Comparative Example 1, ten vacuum insulation materials 1 were produced. After measuring the thermal conductivity of each of the vacuum insulation materials 1, each vacuum insulation material 1 was opened, and the weight of calcium hydroxide, which was the hydroxide 4, was measured.

[0029]

Table 1 indicates the result of the comparison between Example 1 and Comparison Example 1 with respect to the average value of the thermal conductivities of the ten vacuum insulation materials 1, the standard deviation of the thermal conductivity and the weight of the calcium hydroxide.

656600

KPO-3512 [0030] [Table 1]

	Example 1	Comparative Example 1
Average thermal conductivity [mW/(m»K)]	1.8	1.9
Standard deviation of thermal conductivity [mW/(m»K)]	0.1	0.3
Weight of calcium hydroxide [g]	106.8	0.8

[0031]

As illustrated in Table 1, in Comparative Example 1, the average value of the thermal conductivities of the vacuum insulation materials was 1.9 mW/(m»K) and the standard deviation was 0.3 mW/(m*K). The weight of the calcium hydroxide was 0.8 g, which was 0.00016 times the weight of the core.

[0032]

In contrast, in Example 1, the average value of the thermal conductivities of the vacuum insulation materials 1 was 1.8 mW/(m«K), which was smaller than that in Comparative Example 1. That is, in Example 1, a higher heat insulation performance than Comparative Example 1 was obtained. Also, the standard deviation was 0.1 mW/(m*K), which was smaller than that in Comparative Example 1. That is, in Example 1, the variance between the thermal conductivities was smaller than that in Comparative Example 1.

[0033]

Also, in Example 1, the weight of the calcium hydroxide was 106.8 g, which was 0.021 times that of the core.

[0034] <Example 2>

In Example 2, the same sample and conditions as indicated as items (1) to (5) regarding Example 1 were applied. The difference between Examples 1 and 2 resides in that “addition of adsorbent” in step S21 was not carried out in Example 1, whereas it was carried out in Example 2. In the above manner in Example 2, ten vacuum insulation materials 1 were produced. After measuring the thermal conductivity of each of the vacuum insulation materials 1, each vacuum insulation material 1 was opened,

656600 KPO-3512 and the weight of the calcium hydroxide was measured.

[0035]

Also, in Comparative Example 2, the same sample and conditions as indicated in items (1) to (5) regarding Example 1 were applied. Furthermore, in Comparative Example 2, the core 2 and the adsorbent 3 were coated with the enveloping material 5 and the heat treatment was carried out under the condition indicated in item (5) above without sealing the enveloping material 5. Next, the adsorbent 3a was additionally provided, the pressure of the inside of the enveloping material 5 was reduced, and the enveloping material 5 was sealed.

[0036]

Under the above conditions of Comparative Example 2, ten vacuum insulation materials were produced. After measuring the thermal conductivity of each of the vacuum insulation materials, each vacuum insulation material was opened, and the weight of calcium hydroxide was measured.

[0037]

Table 2 indicates the result of comparison between Example 1 and Comparative Example 1 regarding average values of the thermal conductivities of the ten vacuum insulation materials, the standard deviation of the thermal conductivity, and the weight of the calcium hydroxide.

[0038] [Table 2]

	Example 2	Comparative Example 2
Average thermal conductivity [mW/(m»K)]	1.7	1.8
Standard deviation of thermal conductivity [mW/(m»K)]	0.1	0.2
Weight of calcium hydroxide [g]	120.4	15.2

[0039]

As indicated in Table 2, in Comparative Example 2, the average thermal conductivity of the vacuum insulation materials was 1.8 mW/(m*K) and the standard deviation was 0.2 mW/(m*K). The weight of the calcium hydroxide was 15.2 g, which was 0.0030 times the weight of the core.

656600 KPO-3512 [0040]

In contrast, in Example 2, the average thermal conductivity of the vacuum insulation materials 1 was 1.7 mW/(m»K), which was smaller than that in Comparative Example. That is, in Example 2, a higher heat insulation performance than that of Comparative Example 2 was obtained. Also, the standard deviation was 0.1 mW/(m*K), which was smaller than that in Comparative Example 2. That is, in Example 2, the variance between the thermal conductivities was smaller than that in Comparative Example 2.

[0041]

Also, in Example 2, the weight of calcium hydroxide was 120.4 g, which was 0.024 times the weight of the core.

[0042] <Example 3>

In Example 3, the same conditions as indicated in item (1), (2), (4), and (5) regarding Example 1 were applied. As the adsorbent 3, calcium oxide was used. Vacuum insulation materials 1 were produced in indicated in the production process chart of Fig. 2 in units often vacuum insulation materials 1 while changing the weights of calcium oxides to be used as absorbents 3, from 10 g to 100 g. That is, each time ten vacuum insulation materials 1 were produced, the weights of calcium oxides to be used as adsorbents 3 in the vacuum insulation materials 1 were increased in increments of 10 g. To be more specific, ten vacuum insulation materials 1 including as the adsorbents 3, calcium oxides each of which was 10 g in weight were produced; then, ten vacuum insulation materials 1 including as the adsorbents 3, calcium oxides each of which was 20 g in weight were produced; and similarly, subsequent vacuum insulation materials 1 were produced in units of ten vacuum insulation materials 1 such that every ten vacuum insulation materials 1 include calcium oxides whose weight was increased by 10 g from the weight of each of calcium oxides of one-previously produced ten vacuum insulation materials 1. It should be noted that “addition of adsorbent” in step S21 in Fig. 2 was not carried out. Then, after measuring the thermal conductivity of each of the vacuum insulation materials produced as described above, each vacuum

656600

KPO-3512 insulation material 1 was opened, and the weight of the calcium hydroxide, which was the hydroxide 4, was measured. With respect to the relationship between “thermal conductivity” and “ratio of the weight of calcium hydroxide to the weight of the core”, those of the vacuum insulation materials 1 are plotted in Fig. 4.

[0043]

Fig. 4 is a diagram illustrating relationships between thermal conductivities and ratios of the weights of calcium hydroxides to the weights of cores, which were obtained under the above conditions and the above manner in Example 3 regarding the vacuum insulation material according to Embodiment 1 of the present invention. In Fig. 4, the horizontal axis represents the ratio of the weight of calcium hydroxide to the weight of the core [times] and the vertical axis represents the thermal conductivity [mW/(m*K)]. Also, in Fig. 4, a cluster of plotted points roughly arranged in the vertical direction indicates calcium oxides having the same weight, and clusters of plotted points indicate respective groups of calcium oxides which are 10 g, 20 g, . . . 100 g in weight from the left.

[0044]

As illustrated in Fig. 4, in vacuum insulation materials in each of which the weight of the calcium hydroxide was 0.01 times or more the weight of the core 2, the variance between their thermal conductivities and the variance between their heat insulation performances are both small. Also, in the vacuum insulation materials in each of which the weight of the calcium hydroxide was 0.01 times or more the weight of the core 2, 50 g or more of calcium oxide was used as the adsorbent 3.

[0045]

Generally, the weight of the moisture held by the core 2 before the heat treatment is 0.005 times that of the core 2 at the maximum. Also, the molecular weight of calcium hydroxide is approximately 4 times that of water. Therefore, if the weight of the calcium hydroxide is 0.01 times or more that of the core that is multiplied by 0.005 and 4, it means that almost all the moisture released from the core 2 is held by the calcium hydroxide. That is, it can be said that in the vacuum insulation material 1 in which the weight of calcium hydroxide is 0.01 times or more that of the core 2, the

656600

KPO-3512 amount of moisture released from the core 2 does not vary after the pressure of the inside of the enveloping material 5 is reduced and the enveloping material 5 is sealed. Since the amount of moisture released from the core 2 does not vary after the pressure of the inside of the enveloping material 5 is reduced and the enveloping material 5 is sealed, it is possible to obtain vacuum insulation materials 1 such that the variance between the degrees of vacuum in enveloping materials 5 and the variance between the heat insulation performances are both small.

[0046]

It should be noted that in Example 1 described above, vacuum insulation materials 1 in each of which the weight of calcium hydroxide was 0.021 times that of the core 2, that is, it was satisfied that the weight of calcium hydroxide was 0.01 times or more that of the core 2, were obtained; and in Example 2, vacuum insulation materials 1 in each of which the weight of calcium hydroxide was 0.024 times that of the core 2, that is, it was satisfied that the weight of calcium hydroxide was 0.01 times or more that of the core 2, were obtained. Therefore, in both Examples 1 and 2, the variance between the heat insulation performances of the obtained vacuum insulation materials is small. [0047]

It should be noted that the lower limit of the ratio of the weight of the calcium hydroxide to the weight of the core is 0.01 times or more as described above, and the upper limit of the ratio is 0.1 times. The upper limit is set to 0.1 times for the following reason. If the ratio is more than 0.1, the heat insulation performance is deteriorated, and the cost is increased, as a result of which a vacuum insulation material satisfying such a ratio cannot industrially be put to practical use.

[0048]

Embodiment 2

Fig. 5 is a sectional view illustrating a schematic configuration of a heat insulation box according to Embodiment 2 of the present invention.

As illustrated in Fig. 5, a heat insulation box 100 is used as a casing of, for example, a refrigerator or another apparatus, which is required to have a high heat insulation performance. The heat insulation box 100 includes an inner box 110 and an

656600 KPO-3512 outer box 120. The vacuum insulation material 1 as described regarding Embodiment 1 is provided in space between the inner box 110 and outer box 120 to thermally insulate the inner box 110 and outer box 120. The vacuum insulation material 1 is provided, for example, in tight contact with an outer wall 110a of the inner box 110 and located between the inner box 110 and outer box 120 to achieve thermal insulation.

Part of the space between the inner box 110 and the outer box 120 that is other than the vacuum insulation material 1 is filled with a polyurethane foam insulation material 130. [0049]

In such a manner, the heat insulation box 100 is provided with a vacuum insulation material 1 having a thermal conductivity that does not greatly vary from that of each of other produced vacuum insulation materials. Therefore, the heat insulation box 100 can also be produced in such a manner as to have a heat insulation performance that does not greatly vary from that of each of other produced heat insulation boxes 100. As a result, the energy consumption of a refrigerator or another apparatus that is provided with the above heat insulation box 100 can be reduced. [0050]

Furthermore, the vacuum insulation material 1 has a higher heat insulation performance than the polyurethane foam insulation material 130 and other heat insulation materials. Thus, the heat insulation box 100 obtains a higher heat insulation performance than a heat insulation box 100 using only the polyurethane foam insulation material 130. It should be noted that although it is described above as a configuration that the space between the inner box 110 and the outer box 120 is filled with the polyurethane foam insulation material 130, the polyurethane foam insulation material 130 may be omitted because the vacuum insulation material 1 has a higher heat insulation performance than the polyurethane foam insulation material 130 and other heat insulation materials.

[0051]

Also, although it is described above that the vacuum insulation material 1 is provided in tight contact with the outer wall 110a of the inner box 110, the vacuum insulation material 1 may be provided in tight contact with an inner wall 120a of the

656600

KPO-3512 outer box 120. Also, a spacer or spacers or other elements may be provided to prevent the vacuum insulation material 1 from being in tight contact with both of the inner box 110 and the outer box 120 in the space between the inner box 110 and the outer box 120.

[0052]

It should be noted that in the above description, explanations of parts that are equivalent to those of heat insulation boxes 100 used in common refrigerators and other apparatuses are omitted, and in the figures, illustrations of such parts are omitted. [0053]

Also, the vacuum insulation material of the present invention is not limited to those according to the above embodiments, and can be variously modified, and the above embodiments and modifications thereof can be put practical use in combination. [0054]

Also, in Embodiment 2 described above, it is described above as an example of a configuration that the vacuum insulation material 1 is used in the heat insulation box of a refrigerator provided with a cooling energy source (not illustrated); however, the present invention is not limited to such a configuration. The vacuum insulation material 1 can also be used in heat insulation boxes of heat storages provided with a heating energy source, and in heat insulation boxes, such as cooler boxes, which are provided with neither a cooling energy source nor a heating energy source. Also, the vacuum insulation material 1 can be used not only in heat insulation boxes, but in heat insulation elements of cooling energy apparatuses or heating energy apparatuses such as airconditioning apparatuses, vehicle air-conditioning devices, or hot water supplies. Also, the shape of the vacuum insulation material 1 is not limited to a predetermined invariable shape, and may be a variable shape. As a vacuum insulation material 1 having a variable shape, for example, a heat insulation bag having an inner bag and outer bag or a heat insulation container is present.

Reference Signs List [0055] vacuum insulation material, 2 core, 3 adsorbent, 4 hydroxide,

656600

KPO-3512 5 enveloping material, 100 heat insulation box, 110 inner box, 110a outer wall, 120 outer box, 120a inner wall, 130 polyurethane foam insulation material

Claims

656600 KPO-3512 CLAIMS [Claim 1]

A vacuum insulation material comprising:

a core configured to maintain a vacuum space;

hydroxide; and an enveloping material configured to cover the core and the hydroxide, wherein a pressure of an inside of the enveloping material is reduced and the enveloping material is sealed, and a weight of the hydroxide is 0.01 times or more that of the core.
[Claim 2]

The vacuum insulation material of claim 1, wherein the hydroxide is calcium hydroxide.
[Claim 3]

The vacuum insulation material of claim 1 or 2, wherein the enveloping material is coated with an adsorbent that adsorbs moisture.
[Claim 4]

The vacuum insulation material of claim 3, wherein the adsorbent is calcium oxide.
[Claim 5]

The vacuum insulation material of any one of claims 1 to 4, wherein the core is a fiber assembly.
[Claim 6]

The vacuum insulation material of claim 5, wherein the fiber assembly is glass wool.
[Claim 7]

A heat insulation box comprising the vacuum insulation material of any one of claims 1 to 6.
[Claim 8]

A method for producing a vacuum insulation material, the method comprising:

656600

KPO-3512 a sealed-body forming step of coating a core configured to maintain a vacuum space and hydroxide with an enveloping material, and sealing the enveloping material, thereby forming a sealed body;

a heat-treatment step of performing heat treatment on the sealed body; and

5 a pressure-reduction and sealing step of reducing a pressure of an inside of the enveloping material of the sealed body to seal the enveloping material.
[Claim 9]

The method of claim 8, wherein in the sealed-body forming step, a first adsorbent that adsorbs moisture is also coated with the enveloping material and the enveloping 10 material is sealed.
[Claim 10]

The method of claim 8 or 9, further comprising:

a step of adding a second adsorbent to the inside of the enveloping material, which is carried out between the heat-treatment step and the pressure-reduction and

15 sealing step.