JPWO2019171566A1 - Vacuum heat insulating material and heat insulating box - Google Patents

Abstract

The vacuum heat insulating material is a vacuum heat insulating material provided with a core material for holding a vacuum space, an adsorbent for adsorbing moisture, and an outer packaging material for coating the core material and the adsorbent, and the inside of the outer packaging material is vacuum-sealed. The outer packaging material is composed of a surface protective layer, a gas barrier layer containing at least two types of gas barrier films, and a heat-welded layer, and the at least two types of gas barrier films are heated at 100 ° C. for 2 hours or more. In addition, the difference in shrinkage between at least two types of gas barrier films is within 2%.

Description

The present invention relates to a vacuum heat insulating material and a heat insulating box having a gas barrier layer in the outer packaging material.

Conventionally, as a vacuum heat insulating material used as a heat insulating material for a refrigerator or the like, the core material that holds the vacuum space is covered with two outer packaging materials together with an adsorbent that adsorbs water vapor, and the inside of the outer packaging material is formed by vacuum sealing. Vacuum heat insulating materials are known.

The outer packaging material is composed of a surface protective layer, a gas barrier layer, and a heat welding layer. The thermal conductivity of the vacuum heat insulating material is reduced by maintaining the inside in a vacuum by the outer packaging material.

As a known technique, Patent Document 1 discloses a technique in which two inorganic vapor-deposited films constituting a gas barrier layer are superposed with the inorganic-deposited surfaces facing each other. Further, Patent Document 2 discloses a technique of using a biaxially stretched ethylene vinyl alcohol film for a vacuum heat insulating material having a dry heat shrinkage rate of 2% or less in the width direction and the length direction of the film.

Japanese Unexamined Patent Publication No. 2012-219955 Japanese Unexamined Patent Publication No. 2005-1240

In the vacuum heat insulating material, the degree of vacuum decreases due to the intrusion of water vapor into the inside, the thermal conductivity increases, and the heat insulating performance deteriorates. It is considered that the invasion route of water vapor into the inside of the vacuum heat insulating material is a route from the surface of the outer packaging material and a route from the heat-welding layer formed by fusing the two outer packaging materials.

In the technique of Patent Document 1, an attempt is made to superimpose inorganic vapor deposition layers of a gas barrier film to prevent variations in vapor deposition and suppress the intrusion of water vapor. Here, the vacuum heat insulating material is manufactured through a heat drying step. Therefore, when the gas barrier film shrinks and vapor deposition cracks occur, the vacuum state inside the vacuum heat insulating material is not maintained for a long period of time, and an increase in thermal conductivity cannot be suppressed.

Further, in the technique of Patent Document 2, the difference in shrinkage ratio between the width direction and the length direction of each gas barrier film is limited, and an attempt is made to suppress distortion during vapor deposition. However, if the difference in shrinkage rate when the gas barrier film shrinks after the vacuum heat insulating material has undergone the heat drying step is large, thin-film deposition cracking occurs. Also in this case, the vacuum state inside the vacuum heat insulating material is not maintained for a long period of time, and the increase in thermal conductivity cannot be suppressed.

The present invention is for solving the above problems, and is a vacuum heat insulating material and a heat insulating box which can maintain the heat insulating performance for a long period of time without deteriorating the gas barrier property of the outer packaging material even after undergoing the drying process by heating at the time of manufacturing. The purpose is to provide.

The vacuum heat insulating material according to the present invention includes a core material for holding a vacuum space, an adsorbent for adsorbing moisture, and an outer packaging material for coating the core material and the adsorbent, and the inside of the outer packaging material is provided. The vacuum heat insulating material sealed under reduced pressure, the outer packaging material is composed of a surface protective layer, a gas barrier layer containing at least two types of gas barrier films, and a heat-welding layer, and the at least two types of gas barrier films are When heated at 100 ° C. for 2 hours or more, the difference in shrinkage ratio between the at least two types of gas barrier films is within 2%.

The heat insulating box according to the present invention includes the above vacuum heat insulating material.

According to the vacuum heat insulating material and the heat insulating box according to the present invention, the difference in shrinkage between the at least two types of gas barrier films is within 2% when heated at 100 ° C. for 2 hours or more. .. As a result, the difference in the amount of shrinkage between the at least two types of gas barrier films does not become excessively large after the drying step by heating at the time of production, and vapor deposition cracking and the like are suppressed. Therefore, the gas barrier property of the outer packaging material does not deteriorate even after the drying step by heating at the time of manufacturing, and the heat insulating performance can be maintained for a long period of time.

It is sectional drawing which shows the schematic structure of the vacuum heat insulating material which concerns on Embodiment 1 of this invention. It is a chart which shows the result of having compared the increase amount of the thermal conductivity of the vacuum heat insulating material in the sample of Example 1 and Comparative Example 1 which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between the difference between the water vapor permeability and the shrinkage rate of the outer packaging material in Example 1 and Comparative Example 1 which concerns on Embodiment 1 of this invention. It is a chart which shows the result of having compared the increase amount of the thermal conductivity of the vacuum heat insulating material in the sample of Example 2 which concerns on Embodiment 1 of this invention. It is a chart which shows the result of having compared the increase amount of the thermal conductivity of the vacuum heat insulating material in the sample of Example 3 which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the schematic structure of the heat insulation box which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, those having the same reference numerals are the same or equivalent thereof, and they are common in the entire text of the specification. Further, in the cross-sectional view, hatching is appropriately omitted in view of visibility. Furthermore, the forms of the components shown in the full text of the specification are merely examples and are not limited to these descriptions.

Embodiment 1.
<Composition of vacuum heat insulating material>
FIG. 1 is a cross-sectional view showing a schematic configuration of the vacuum heat insulating material 1 according to the first embodiment of the present invention. In the following drawings including FIG. 1, the relationship or shape of the dimensions of each component may differ from the actual one. The specific dimensions of each constituent material should be determined with reference to the following explanation.

As shown in FIG. 1, the vacuum heat insulating material 1 is a heat insulating material that realizes low thermal conductivity by creating a vacuum inside. The vacuum heat insulating material 1 has a substantially rectangular flat plate shape as a whole. The vacuum heat insulating material 1 includes a core material 2, an adsorbent 3, and an outer packaging material 4.

The core material 2 holds a vacuum space. The adsorbent 3 adsorbs at least water. The outer packaging material 4 covers the core material 2 and the adsorbent 3.

The internal vacuum space sealed by the outer packaging material 4 is decompressed from the opening, and the opening is fused by heat sealing or the like, so that the inside of the outer packaging material 4 is decompressed and sealed.

<Structure of core material 2>
The core material 2 is used for the purpose of maintaining a vacuum space. As the core material 2, it is common to use a fiber aggregate such as glass wool. Further, the fiber aggregate constituting the core material 2 may be one that has been heat-press molded, one that has been hermetically sealed using an encapsulating material, or one that has been bound with a binder.

<Structure of Adsorbent 3>
The adsorbent 3 adsorbs the water vapor inside the vacuum heat insulating material 1 and suppresses an increase in the heat transfer coefficient by maintaining the degree of vacuum. Calcium oxide is used as the adsorbent 3. Calcium oxide is sometimes abbreviated as CaO.

<Structure of outer packaging material 4>
The outer packaging material 4 is composed of two laminated films having a multilayer structure of a surface protective layer 41, a gas barrier layer 42, and a heat welding layer 43. In the outer packaging material 4, the heat-welding layers 43 are fused to each other and joined at the sealing portion 43a to coat the core material 2 and the adsorbent 3. At this time, in the outer packaging material 4, the sealing portion 43a is fused in a state where the pressure is reduced to about 1 to 3 Pa (Pascal), and the inside is sealed under reduced pressure.

The outer packaging material 4 may have different thicknesses of the heat welding layers 43. As the outer packaging material 4 that covers the core material 2 and the adsorbent 3, two outer packaging materials 4 may be used, or one outer packaging material 4 may be folded and used. The number of outer packaging materials 4 is not limited as long as the core material 2 and the adsorbent 3 can be sealed under reduced pressure.

<Structure of surface protection layer 41>
The film thickness of the surface protective layer 41 is 25 μm or the like. The material of the surface protective layer 41 is preferably a thermoplastic resin having a melting point of 150 ° C. or higher and excellent scratch resistance. For example, stretched polyamide such as stretched nylon, polyethylene terephthalate, stretched polypropylene, and the like can be used. Stretched nylon may be abbreviated as ONY. Polyethylene terephthalate is sometimes abbreviated as PET. Stretched polypropylene is sometimes abbreviated as OPP.

<Structure of gas barrier layer 42>
For the gas barrier layer 42, a thermoplastic resin having excellent water vapor and air blocking properties is selected as the material. The gas barrier layer 42 is formed by, for example, laminating two gas barrier films having a film thickness of 12 μm. The gas barrier layer 42 may include at least two types of gas barrier films. That is, the gas barrier layer 42 may be formed not only by laminating two types of two gas barrier films, but also by laminating two or three or more types of three or more gas barrier films.

The material of the gas barrier layer 42 is inorganic-deposited polyethylene terephthalate, inorganic-deposited ethylene vinyl alcohol, or two types of gas barrier films having a shrinkage difference of 2% or less when heated at 100 ° C. for 2 hours. A combination of the above may be used. Then, the gas barrier layer 42 is laminated with the surfaces of the two gas barrier films subjected to inorganic vapor deposition facing each other. When the gas barrier layer 42 is composed of three or more gas barrier films, the front and back surfaces of the gas barrier films sandwiched between the gas barrier layers 42 may be subjected to inorganic vapor deposition, and the surfaces to which the inorganic vapor deposition has been subjected to the inorganic vapor deposition may be faced to each other. The inorganic material deposited on the thermoplastic resin is not limited to aluminum, and may be alumina, silica, or a combination thereof. Ethylene vinyl alcohol is sometimes abbreviated as EVOH.

The shrinkage ratio was calculated from the dimensional change after each gas barrier film was cut into 250 mm square lengths and dried at 100 ° C. for 2 hours. Further, the shrinkage rate is a fixed value even if the size of each gas barrier film changes.

<Structure of heat welding layer 43>
The film thickness of the heat welding layer 43 is 30 μm or the like. As the material of the heat welding layer 43, a thermoplastic resin having a melting point of 150 ° C. or lower is selected. However, the material of the heat welding layer 43 is not particularly specified. As the heat welding layer 43, for example, low-density polyethylene or linear low-density polyethylene is used. The heat-welded layer 43 may be made of high-density polyethylene having a high elastic modulus and excellent water vapor blocking property, or unstretched polypropylene. Low density polyethylene is sometimes abbreviated as LDPE. Linear low density polyethylene is sometimes abbreviated as LLDPE. High density polyethylene is sometimes abbreviated as HDPE. Unstretched polypropylene may be abbreviated as CPP. In the following description, the above abbreviations are described in parentheses.

The laminated film is the vacuum heat insulating material 1 before evacuation, and forms the gas barrier layer 42 even if it is heat-dried at 100 ° C. for 2 hours or more in a state where at least three sides are heat-welded. It is desirable that the difference in shrinkage of the gas barrier film is within 2%.

<Manufacturing process of vacuum heat insulating material 1>
In the manufacturing process of the vacuum heat insulating material 1, first, the core material 2 is covered with the outer packaging material 4 having a multi-layer structure of the surface protective layer 41, the gas barrier layer 42, and the heat welding layer 43. Then, the core material 2 and the outer packaging material 4 are dried. Moisture is removed from the core material 2 and the outer packaging material 4 by heat-treating the core material 2 coated with the outer packaging material 4 at 100 ° C. for 2 hours or more. At this time, the difference in shrinkage after heat treatment is within 2% in at least two or more gas barrier films forming the gas barrier layer 42. As a result, the occurrence of cracks on the inorganic vapor-filmed surface can be suppressed, and the heat insulating performance can be maintained for a long period of time without deteriorating the gas barrier property.

Next, the adsorbent 3 is arranged between the core material 2 and the outer packaging material 4. After that, the inside of the outer packaging material 4 is depressurized to a degree of vacuum of about 1 to 3 Pa, and in the reduced pressure state, the opening of the outer packaging material 4 is fused by a heat seal or the like, and the inside of the outer packaging material 4 is decompressed and sealed.

The vacuum heat insulating material 1 obtained through the above steps has a shrinkage difference of 2% or less after heat treatment in at least two types of gas barrier films in which the inorganic vapor deposition surfaces constituting the gas barrier layer 42 are opposed to each other. is there. As a result, the generation of cracks in the inorganic thin-film deposition layer can be suppressed, the degree of vacuum inside the vacuum heat insulating material 1 is maintained, and the state in which the amount of increase in thermal conductivity is suppressed can be maintained for a long period of time.

<Comparison between Examples and Comparative Examples>
The vacuum heat insulating material 1 of the first embodiment was produced, and the Example was compared with the Comparative Example. The comparison results will be described below.

Example 1.
In Example 1, aluminum-deposited ethylene vinyl alcohol (EVOH) and silica-deposited stretched nylon (ONY) were used as the two gas barrier films constituting the gas barrier layer 42 of the outer packaging material 4 of the vacuum heat insulating material 1. Then, the relationship between the water vapor permeability of the outer packaging material 4 and the amount of increase in the thermal conductivity of the vacuum heat insulating material 1 due to the difference in shrinkage between the silica-deposited stretched nylon (ONY) and the aluminum-deposited ethylene vinyl alcohol (EVOH). I investigated the relationship and.

As the surface protective layer 41 of the outer packaging material 4, stretched nylon (ONY) having a film thickness of 25 μm was used. As the gas barrier layer 42, silica-deposited stretched nylon (ONY) having a thickness of 12 μm and aluminum-deposited ethylene vinyl alcohol (EVOH) having a thickness of 12 μm were used. As the heat welding layer 43, unstretched polypropylene (CPP) having a film thickness of 30 μm was used. The core material 2 of the vacuum heat insulating material 1 was made of glass wool.

A laminated film in which the surface protective layer 41, the gas barrier layer 42, and the heat welding layer 43 of the above specifications are laminated is used as the outer packaging material 4, and the core material 2 is covered with the outer packaging material 4 to prepare the vacuum heat insulating material 1. did.

Regarding the water vapor permeability, the water vapor permeability of a piece of the laminated film of the outer packaging material 4 dried at 100 ° C. for 2 hours or more was examined under the condition of 40 ° C. and 90% RH. For the measurement, GTR-1000XAMD manufactured by GTR Tech Co., Ltd. was used.

Regarding the amount of increase in thermal conductivity, the thermal conductivity immediately after the production of the vacuum heat insulating material 1 and the thermal conductivity after storing the vacuum heat insulating material 1 in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% for 30 days. And, the difference was calculated as the amount of increase.

In the sample of Example 1, the gas barrier layer 42 had a thickness of 12 μm, in which the difference in shrinkage between the aluminum-deposited ethylene vinyl alcohol (EVOH) having a thickness of 12 μm and the aluminum-deposited ethylene vinyl alcohol (EVOH) was smaller than 2%. The vacuum heat insulating material 1 having silica-film-deposited stretched nylon (ONY) was used.

In the sample used in Comparative Example 1, the gas barrier layer 42 of the outer packaging material 4 of the vacuum heat insulating material 1 had a thickness difference of 2.2% and 2.3% in shrinkage ratio from aluminum-deposited ethylene vinyl alcohol (EVOH). 12 μm silica vapor deposition stretched nylon (ONY) was used. Other configurations and conditions were the same as those of the sample of Example 1.

FIG. 2 is a table showing the results of comparing the amount of increase in the thermal conductivity of the vacuum heat insulating material 1 in the samples of Example 1 and Comparative Example 1 according to the first embodiment. FIG. 3 is a diagram showing the relationship between the difference in water vapor permeability and shrinkage rate of the outer packaging material 4 in Example 1 and Comparative Example 1 according to the first embodiment.

As shown in FIGS. 2 and 3, the shrinkage ratio of each gas barrier film after heat-drying at 100 ° C. for 2 hours gave the following results. The aluminum-deposited ethylene-vinyl alcohol film had a shrinkage rate of 2.6%. The silica-deposited stretched nylon film of the sample of Example 1 had shrinkage rates of 1.2% and 0.8%. The silica-deposited stretched nylon film of the sample of Comparative Example 1 had shrinkage rates of 0.4% and 0.2%.

Further, the water vapor permeability of the laminated film having the silica-deposited stretched nylon film and the aluminum-deposited ethylene vinyl alcohol film of the sample of Example 1 in the gas barrier layer 42 was 2.4 mg / (m ² · day) and 2.5 mg. was / ^(m 2 · day). The water vapor permeability of the laminated film having the silica-deposited stretched nylon film and the aluminum-deposited ethylene vinyl alcohol film of the sample of Comparative Example 1 on the gas barrier layer 42 was 7.7 mg / (m ² · day) and 9.6 mg / (. It was m ² · day).

From the above results, when the difference in shrinkage ratio between the silica-deposited stretched nylon film and the aluminum-deposited ethylene-vinyl alcohol film exceeds 2%, the water vapor permeability tends to increase sharply. That is, as shown in FIG. 3, a graph is used in which the difference in shrinkage ratio is taken on the horizontal axis and the water vapor permeability is taken on the vertical axis. On FIG. 3, the water vapor permeability of 2.4 mg / (m ² · day) of the sample in Example 1 in FIG. 2 is plotted as a. The water vapor permeability of 2.5 mg / (m ² · day) of the sample in Example 1 is plotted as b. The water vapor permeability of 7.7 mg / (m ² · day) of the sample in Comparative Example 1 is plotted as c. The water vapor permeability of 9.6 mg / (m ² · day) of the sample in Comparative Example 1 is plotted as d. These points a to d were connected and compared with the difference in shrinkage rate. As a result, assuming that the point where the difference in shrinkage rate is 2% is an inflection point, the water vapor permeability is maintained in a gently small state at a distance of 2% or less from the inflection point. On the other hand, when the difference in shrinkage exceeds 2% from the vicinity of the inflection point where the difference in shrinkage is 2%, the water vapor permeability increases sharply. Therefore, it can be considered that the point where the difference in shrinkage rate is 2% is an inflection point and has a critical significance.

As shown in FIG. 2, the thermal conductivity of the vacuum heat insulating material 1 of Example 1 and Comparative Example 1 immediately after production was 1.8 mW / (m · K). The amount of increase in thermal conductivity of the vacuum heat insulating material 1 of Example 1 after storage for 30 days in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% was 0.6 mW / (m · K) and 0.7 mW /. It was (m ・ K). The thermal conductivity of the vacuum heat insulating material 1 of Comparative Example 1 after storage for 30 days in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% was 1.1 mW / (m · K) and 1.2 mW / (m ·). It was K).

From the above results, when the difference in shrinkage ratio between the silica-deposited stretched nylon film and the aluminum-deposited ethylene-vinyl alcohol film exceeds 2%, the amount of increase in thermal conductivity tends to increase sharply.

As described above, silica-film-deposited stretched nylon (ONY) having a shrinkage difference of 2% or less from aluminum-deposited ethylene vinyl alcohol (EVOH) after being heat-dried at 100 ° C. for 2 hours using Example 1 as an example. ) Was used, and good results were obtained. That is, a high gas barrier property could be maintained even after the heat-drying step, and a low increase in heat transfer coefficient could be maintained for a long period of time.

Example 2.
In Example 2, aluminum-deposited ethylene vinyl alcohol (EVOH) and silica-deposited polyethylene terephthalate (PET), which are two gas barrier films constituting the gas barrier layer 42 of the outer packaging material 4 of the vacuum heat insulating material 1, were used. Then, for Example 2, the amount of increase in the water vapor permeability of the outer packaging material 4 and the thermal conductivity as the vacuum heat insulating material 1 was compared with the sample of Example 1.

As the surface protective layer 41 of the outer packaging material 4, stretched nylon (ONY) having a film thickness of 25 μm was used. As the gas barrier layer 42, silica-deposited polyethylene terephthalate (PET) having a film thickness of 12 μm and aluminum-deposited ethylene vinyl alcohol (EVOH) having a film thickness of 12 μm were used. As the heat welding layer 43, unstretched polypropylene (CPP) having a film thickness of 30 μm was used. The core material 2 of the vacuum heat insulating material 1 was made of glass wool.

A laminated film in which the surface protective layer 41, the gas barrier layer 42, and the heat welding layer 43 of the above specifications are laminated is used as the outer packaging material 4, and the core material 2 is covered with the outer packaging material 4 to prepare the vacuum heat insulating material 1. did.

Regarding the amount of increase in thermal conductivity, the thermal conductivity immediately after the production of the vacuum heat insulating material 1 and the thermal conductivity after storing the vacuum heat insulating material 1 in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% for 30 days are determined. Was investigated, and the difference was calculated as the amount of increase.

In the sample of Example 2, the gas barrier layer 42 had a film thickness of 12 μm in which the difference in shrinkage between the aluminum-deposited ethylene vinyl alcohol (EVOH) having a thickness of 12 μm and the aluminum-deposited ethylene vinyl alcohol (EVOH) was smaller than 2%. A vacuum insulating material 1 having silica-deposited polyethylene terephthalate (PET) was used.

FIG. 4 is a table showing the results of comparing the amount of increase in the thermal conductivity of the vacuum heat insulating material 1 in the sample of Example 2 according to the first embodiment of the present invention.

As shown in FIG. 4, the shrinkage rate of each gas barrier film after being heat-dried at 100 ° C. for 2 hours was as follows. The aluminum-deposited ethylene-vinyl alcohol film had a shrinkage rate of 2.6%. The silica-deposited polyethylene terephthalate film of the sample of Example 2 had a shrinkage rate of 1.4%. Water vapor permeability of the laminated film having a gas barrier layer 42 of silica deposited polyethylene terephthalate film sample of Example 2 and the aluminum deposited ethylene vinyl alcohol film was ^{2.2mg / (m 2 · day)} . The thermal conductivity of the vacuum heat insulating material 1 of Example 2 immediately after production was 1.8 mW / (m · K). The amount of increase in the thermal conductivity of the vacuum heat insulating material 1 of Example 2 after storage for 30 days in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% was 0.5 mW / (m · K).

In Example 2, a polyethylene terephthalate film having a lower water vapor permeability than that of stretched nylon is used as a base material as compared with Example 1 in FIG. As a result, in Example 2, a higher gas barrier property than in Example 1 could be maintained, and a low increase in heat transfer coefficient could be maintained over a long period of time.

Example 3.
In Example 3, aluminum-deposited ethylene vinyl alcohol (EVOH) and alumina-deposited polyethylene terephthalate (PET), which are two gas barrier films constituting the gas barrier layer 42 of the outer packaging material 4 of the vacuum heat insulating material 1, were used. In Example 3, the amount of increase in the water vapor permeability of the outer packaging material 4 and the thermal conductivity of the vacuum heat insulating material 1 was compared with the sample of Example 2.

As the surface protective layer 41 of the outer packaging material 4, stretched nylon (ONY) having a film thickness of 25 μm was used. As the gas barrier layer 42, an alumina-deposited polyethylene terephthalate (PET) having a thickness of 12 μm and an aluminum-deposited ethylene vinyl alcohol (EVOH) having a thickness of 12 μm were used. As the heat welding layer 43, unstretched polypropylene (CPP) having a film thickness of 30 μm was used. In the vacuum heat insulating material 1, the core material 2 is made of glass wool.

A laminated film in which the surface protective layer 41, the gas barrier layer 42, and the heat welding layer 43 of the above specifications are laminated is used as the outer packaging material 4, and the core material 2 is covered with the outer packaging material 4 to prepare the vacuum heat insulating material 1. did.

Regarding the amount of increase in thermal conductivity, the thermal conductivity immediately after the production of the vacuum heat insulating material 1 and the thermal conductivity after storing the vacuum heat insulating material 1 in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% for 30 days are determined. Was investigated, and the difference was calculated as the amount of increase.

In the sample of Example 3, the gas barrier layer 42 had a film thickness of 12 μm in which the difference in shrinkage between the aluminum-deposited ethylene vinyl alcohol (EVOH) having a thickness of 12 μm and the aluminum-deposited ethylene vinyl alcohol (EVOH) was smaller than 2%. A vacuum insulating material 1 having alumina-deposited polyethylene terephthalate (PET) was used.

FIG. 5 is a table showing the results of comparing the amount of increase in the thermal conductivity of the vacuum heat insulating material 1 in the sample of Example 3 according to the first embodiment of the present invention.

As shown in FIG. 5, the shrinkage ratio of each gas barrier film after being heat-dried at 100 ° C. for 2 hours was as follows. The aluminum-deposited ethylene-vinyl alcohol film had a shrinkage rate of 2.6%. The alumina-deposited polyethylene terephthalate film of the sample of Example 3 had a shrinkage rate of 1.2%. The water vapor permeability of the laminated film having the alumina-deposited polyethylene terephthalate film and the aluminum-deposited ethylene vinyl alcohol film of the sample of Example 3 in the gas barrier layer 42 was 1.9 mg / (m ² · day). The thermal conductivity of the vacuum heat insulating material 1 of Example 3 immediately after production was 1.8 mW / (m · K). The amount of increase in the thermal conductivity of the vacuum heat insulating material 1 of Example 3 after storage for 30 days in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% was 0.3 mW / (m · K).

In Example 3, alumina having a lower water vapor permeability than silica was used for vapor deposition as compared with Example 2 in FIG. As a result, in Example 3, a higher gas barrier property than in Example 2 could be maintained, and a low increase in heat transfer coefficient could be maintained over a long period of time.

<Effect of Embodiment 1>
According to the first embodiment, the vacuum heat insulating material 1 includes a core material 2 that holds a vacuum space. The vacuum heat insulating material 1 includes an adsorbent 3 that adsorbs moisture. The vacuum heat insulating material 1 includes an outer packaging material 4 that covers the core material 2 and the adsorbent 3. The vacuum heat insulating material 1 seals the inside of the outer packaging material 4 under reduced pressure. The outer packaging material 4 is composed of a surface protective layer 41, a gas barrier layer 42 including at least two types of gas barrier films, and a heat welding layer 43. When the at least two types of gas barrier films are heated at 100 ° C. for 2 hours or more, the difference in shrinkage ratio between the at least two types of gas barrier films is within 2%.

According to this configuration, the difference in the amount of shrinkage between at least two types of gas barrier films does not differ excessively after undergoing the drying step by heating during production. That is, after the drying step by heating at the time of production, the inorganic vapor deposition of the gas barrier layer 42 is less likely to cause vapor deposition cracks and the like, and the gas barrier property is not deteriorated. Therefore, the degree of vacuum inside the vacuum heat insulating material 1 is maintained, and an increase in the heat transfer coefficient can be suppressed. Therefore, the gas barrier property of the outer packaging material 4 does not deteriorate even after the drying step by heating at the time of production, and the heat insulating performance can be maintained for a long period of time.

According to the first embodiment, the gas barrier layer 42 is laminated with the surfaces of at least two types of gas barrier films subjected to inorganic vapor deposition facing each other.

According to this configuration, after the drying step by heating at the time of production, vapor deposition cracks are less likely to occur in the inorganic vapor deposition in which the surfaces of the gas barrier layer 42 are faced to each other and laminated, and the gas barrier property is not deteriorated. Therefore, the degree of vacuum inside the vacuum heat insulating material 1 is maintained, and an increase in the heat transfer coefficient can be suppressed.

According to the first embodiment, the gas barrier layer 42 is composed of ethylene vinyl alcohol (EVOH) which has been subjected to inorganic vapor deposition and stretched nylon (ONY) which has been subjected to inorganic vapor deposition.

According to this configuration, the difference in shrinkage between the two types of gas barrier films becomes small after the drying step by heating at the time of production. As a result, vapor deposition cracks are less likely to occur in the inorganic vapor deposition of the gas barrier layer 42, and the gas barrier property is not deteriorated. Therefore, the degree of vacuum inside the vacuum heat insulating material 1 is maintained, and an increase in the heat transfer coefficient can be suppressed.

According to the first embodiment, the gas barrier layer 42 is composed of ethylene vinyl alcohol (EVOH) which has been subjected to inorganic vapor deposition and polyethylene terephthalate (PET) which has been subjected to inorganic vapor deposition.

According to this configuration, the difference in shrinkage between the two types of gas barrier films becomes small after the drying step by heating at the time of production. As a result, vapor deposition cracks are less likely to occur in the inorganic vapor deposition of the gas barrier layer 42, and the gas barrier property is not deteriorated. Therefore, the degree of vacuum inside the vacuum heat insulating material 1 is maintained, and an increase in the heat transfer coefficient can be suppressed.

According to the first embodiment, the material to be inorganically vapor-deposited is aluminum, alumina, silica, or a combination thereof.

According to this configuration, thin-film deposition cracks are unlikely to occur in the inorganic vapor deposition after the drying step by heating during manufacturing.

Embodiment 2.
FIG. 6 is a cross-sectional view showing a schematic configuration of the heat insulating box 100 according to the second embodiment of the present invention. The heat insulating box 100 is required to have heat insulating performance for a long period of time, for example, a refrigerator or a freezing device.

As shown in FIG. 6, the heat insulating box 100 has an inner box 110 and an outer box 120. The vacuum heat insulating material 1 described in the first embodiment is arranged in the space between the inner box 110 and the outer box 120. The vacuum heat insulating material 1 insulates between the inner box 110 and the outer box 120. The position where the vacuum heat insulating material 1 is arranged is, for example, a position in close contact with the outer wall surface of the inner box 110. The vacuum heat insulating material 1 may be arranged at a position where heat insulation can be performed between the inner box 110 and the outer box 120.

As described above, the heat insulating box 100 is provided with the vacuum heat insulating material 1 having a low thermal conductivity. As a result, the state in which the thermal conductivity between the inner box 110 and the outer box 120 is low is maintained. Therefore, the heat insulating performance of the heat insulating box 100 can be maintained high for a long period of time. A refrigerator or a refrigerating device provided with a heat insulating box 100 leads to a reduction in power consumption.

The vacuum heat insulating material 1 has higher heat insulating performance than the urethane foam heat insulating material 130 and the like. Therefore, the heat insulating box 100 can obtain higher heat insulating performance than the heat insulating box using only the urethane foam heat insulating material 130. Further, in the space between the inner box 110 and the outer box 120, the portion other than the place where the vacuum heat insulating material 1 is arranged may be filled with the urethane foam heat insulating material 130.

In the above description, the vacuum heat insulating material 1 of the heat insulating box 100 is in close contact with the outer wall surface of the inner box 110. However, the vacuum heat insulating material 1 may be in close contact with the inner wall surface of the outer box 120. The vacuum heat insulating material 1 may be arranged in the space between the inner box 110 and the outer box 120 so as not to be in close contact with either the inner box 110 or the outer box 120 by using a spacer or the like.

In the above description, the illustration and description of the portion equivalent to the heat insulating box used in a general refrigerator or the like are omitted.

<Effect of Embodiment 2>
According to the second embodiment, the heat insulating box 100 includes the vacuum heat insulating material 1 described above.

According to this configuration, in the heat insulating box 100 provided with the vacuum heat insulating material 1, the gas barrier property of the outer packaging material 4 does not deteriorate even after the vacuum heat insulating material 1 has undergone the drying step by heating at the time of manufacture, and the gas barrier property of the outer packaging material 4 does not deteriorate for a long period of time. Insulation performance can be maintained.

<Others>
The vacuum heat insulating material 1 according to the present invention is not limited to the above-described embodiment and can be variously modified, and the above-described embodiments or examples may be carried out in combination with each other.

For example, in the above, it is illustrated that the core material 2 and the outer packaging material 4 are dried by heat treatment at 100 ° C. for 2 hours in the manufacturing process. However, the temperature and time of the heat treatment are not limited as long as the temperature and time can remove the water content of the core material 2 and the outer packaging material 4.

Further, the core material 2 and the outer packaging material 4 are dried in a state where the core material 2 is covered with the outer packaging material 4. However, the core material 2 may be coated with the outer packaging material 4 after the core material 2 and the outer packaging material 4 are dried separately.

Further, in the manufacturing process of the vacuum heat insulating material 1 according to the first embodiment, the adsorbent 3 is arranged between the core material 2 and the outer packaging material 4 after the core material 2 and the outer packaging material 4 are dried. However, the adsorbent 3 may be placed before the core material 2 and the outer packaging material 4 are dried.

Further, in the second embodiment described above, the configuration in which the vacuum heat insulating material 1 is used for the heat insulating box 100 of the refrigerator provided with the cold heat source is given as an example. However, the present invention is not limited to this. The vacuum heat insulating material 1 can also be used for a heat insulating box of a heat insulating chamber provided with a heat source or a heat insulating box not provided with a cold heat source and a heat source, that is, a cooler box or the like. Further, the vacuum heat insulating material 1 may be used not only as the heat insulating box 100 but also as a heat insulating member of a cooling device such as an air conditioner, a vehicle air conditioner, a water heater, or a heating device. In addition, the shape of the vacuum heat insulating material 1 is not a predetermined shape, and may be used for a heat insulating bag or a heat insulating container provided with a deformable outer bag and inner bag.

1 Vacuum heat insulating material, 2 core material, 3 adsorbent, 4 outer packaging material, 41 surface protective layer, 42 gas barrier layer, 43 heat welding layer, 43a sealing part, 100 heat insulating box, 110 inner box, 120 outer box, 130 foam Urethane heat insulating material.

Claims (6)

The core material that holds the vacuum space and
An adsorbent that adsorbs water and
An outer packaging material that coats the core material and the adsorbent,
With
A vacuum heat insulating material in which the inside of the outer packaging material is sealed under reduced pressure.
The outer packaging material is composed of a surface protective layer, a gas barrier layer containing at least two types of gas barrier films, and a heat welding layer.
The at least two types of gas barrier films are vacuum heat insulating materials in which the difference in shrinkage ratio between the at least two types of gas barrier films is within 2% when heated at 100 ° C. for 2 hours or more. The vacuum heat insulating material according to claim 1, wherein the gas barrier layer is formed by facing the surfaces of at least two types of gas barrier films subjected to inorganic vapor deposition and sticking them together. The vacuum heat insulating material according to claim 1 or 2, wherein the gas barrier layer is composed of ethylene vinyl alcohol (EVOH) subjected to inorganic vapor deposition and stretched nylon (ONY) subjected to inorganic vapor deposition. The vacuum heat insulating material according to claim 1 or 2, wherein the gas barrier layer is composed of ethylene vinyl alcohol (EVOH) subjected to inorganic vapor deposition and polyethylene terephthalate (PET) subjected to inorganic vapor deposition. The vacuum heat insulating material according to any one of claims 2 to 4, wherein the inorganic material to be inorganically vapor-deposited is aluminum, alumina, silica, or a combination thereof. A heat insulating box provided with the vacuum heat insulating material according to any one of claims 1 to 5.

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