JPH08338683A - Vacuum insulation material - Google Patents

Abstract

PURPOSE: To prevent an insulation performance from lowering due to drop in the degree of vacuum attributable to the penetration of gases, such as oxygen or moisture or carbon dioxide into a vacuum insulating material. CONSTITUTION: This invention provides a method which maintains an initial degree of vacuum as long as possible and further maintains an insulation performance with a vacuum insulation material which comprises a gas barrier hermetically enclosed vessel, a core material, and an oxygen-absorbing agent which requires no moisture for the absorption of oxygen, a dehumidifying agent, and an acid gas-absorbing agent. The oxygen absorbing agent which needs no moisture for the absorption of oxygen includes an unsaturated aliphatic compound and/or a main agent of a chain hydrocarbon polymer having an unsaturated group, and an oxygen absorption-promoting substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum heat insulating material used in refrigerators, refrigerators and the like.

[0002]

2. Description of the Related Art Up to now, as a heat insulating material for refrigerators, freezers, etc., a shape-containing and convection-preventing structure has been used in a sealed container having a gas barrier property (hereinafter referred to as "gas barrier closed container") made of a plastic film or the like. As a core material (or aggregate) for this purpose, an inorganic material such as pearlite or an organic material such as foamed polyurethane is vacuum-packed at a vacuum degree of 1 torr or less to obtain a thermal conductivity of 0.01 kcal / m. h. A vacuum heat insulating material having a temperature of ℃ or less is considered. However, in these vacuum insulation materials, air and moisture intrude into the gas-barrier closed container to a small extent, and the degree of vacuum in the gas-barrier closed container gradually decreases with the passage of time. There was a problem that it became large and it was not possible to maintain a high degree of heat insulation. Further, in a system using polyurethane foam or the like as the core material, the gas used for the solvent during the production of the core material, the gas used for foaming, or the acidic gas such as carbon dioxide gas generated by the decomposition of the core material itself is a gas barrier closed container. The degree of vacuum inside was lowered. In this way, when air and moisture enter the gas-barrier closed container, or when acidic gas or the like is generated, the degree of vacuum is lowered, and the performance as a vacuum heat insulating material is gradually impaired. Moreover, the power consumption was increased and the running cost was high.

As a conventional technique for solving these problems, Japanese Patent Application Laid-Open No. 58-104081 discloses that a mixture of a porous aggregate such as pearlite and an adsorbent such as molecular sieves that adsorbs air is filled and the inside is filled. A heat insulating material including a vacuumed gas-barrier closed container is disclosed. However, the disclosed adsorptive substance has a drawback that it adsorbs practically only water and hardly adsorbs air.

Japanese Patent Application Laid-Open No. 59-225275 discloses a moisture adsorbing substance such as silica gel and zeolite.
However, since these water-adsorbing substances simply remove water by adsorption, the adsorbed moisture may be
There was a defect that it detached due to changes in temperature.

Further, Japanese Patent Laid-Open No. 63-105392 discloses a vacuum heat insulating material containing iron powder added to the heat insulating material. However, in this case, the reaction between the iron powder and oxygen requires water, and there is a problem that the oxygen absorption reaction does not occur if there is no water on the iron powder. In addition, if water is present in the iron powder in advance in order to allow the reaction to proceed sufficiently, the water vaporizes in the vacuum heat insulating material, conversely the vacuum degree in the gas barrier closed container deteriorates and the heat insulating performance of the vacuum heat insulating material deteriorates. There was a drawback of inviting.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vacuum heat insulating material which suppresses the deterioration of the heat insulating performance of the vacuum heat insulating material and maintains the heat insulating performance originally possessed.

[0007]

Means for Solving the Problems The present inventors can achieve the above object by using an oxygen absorbent, a dehumidifying agent and an acid gas absorbent which do not require water for absorbing oxygen. Found out. That is, it has been found that by removing oxygen, moisture, and generated acid gases such as carbon dioxide gas that enter the vacuum heat insulating material, it is possible to prevent the vacuum degree from lowering and maintain the heat insulating performance. The present invention is a vacuum insulation characterized by enclosing or adding a core material as an aggregate and an oxygen absorbent, a dehumidifying agent and an acid gas absorbent which do not require water to absorb oxygen, in a gas barrier closed container. It is a material. That is, the present invention is a vacuum heat insulating material including a gas barrier closed container, a core material, an oxygen absorbent that does not require moisture to absorb oxygen, a dehumidifying agent and an acidic gas absorbent.
Further, the present invention is an oxygen absorbent which does not require water for absorbing oxygen, wherein the oxygen absorbent contains a main component of a chain hydrocarbon polymer having an unsaturated fatty acid compound and / or an unsaturated group and an oxygen absorption promoter. is there. In the present invention, the acidic gas absorbent is at least one selected from oxides, hydroxides, carbonates, organic acid salts and organic amines of alkali metals or alkaline earth metals.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The main agent of the oxygen absorbent used in the present invention is not particularly limited as long as it does not require water to absorb oxygen, but it has an unsaturated fatty acid compound or an unsaturated group. Unsaturated organic compounds such as chain hydrocarbons,
Examples of the oxygen absorber include a thermoplastic polymer such as polyamide or polyolefin as a main agent and an oxygen absorption promoter such as a transition metal salt. An unsaturated fatty acid compound and / or a chain hydrocarbon polymerization having an unsaturated group An oxygen absorbent containing a substance as a main agent and containing an oxygen absorption promoting substance is preferable.

The unsaturated fatty acid compound used here is
It is an unsaturated fatty acid having 10 or more carbon atoms and having a double bond between carbons, or a salt or ester of the unsaturated fatty acid. When the carbon number is 10 or less, when the pressure is reduced to a low pressure, the vapor pressure cannot be ignored and the pressure is not sufficiently lowered, which is inconvenient. The unsaturated fatty acid and the salt or ester of the fatty acid may have a substituent such as a hydroxyl group and a formyl group. Further, the unsaturated fatty acid compound does not necessarily have to be a pure substance.

Examples of unsaturated fatty acid compounds include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, parinaric acid, dimer acid, and ricinoleic acid, and soybean oil, tung oil containing these esters,
Examples include oils and fats such as linseed oil, sesame oil, cottonseed oil, esters, and metal salts. Moreover, vegetable oil as an unsaturated fatty acid, a fatty acid obtained from animal oil, that is, linseed oil fatty acid,
Soybean oil fatty acid, tung oil fatty acid, bran oil fatty acid, sesame oil fatty acid, cottonseed oil fatty acid, rapeseed oil fatty acid, tall oil fatty acid and the like are also used. These unsaturated fatty acid compounds may be used alone or in combination of two or more.

The chain hydrocarbon polymer having an unsaturated group is a polymer having 10 or more carbon atoms and at least one double bond between carbon atoms and its derivatives. When the number of carbon atoms is 10 or less, the vapor pressure cannot be ignored and the pressure is not sufficiently lowered, which is inconvenient, when the pressure is set to a low pressure as in the case of the unsaturated fatty acid compound. The derivative may have, for example, a hydroxyl group, an amino group, a formyl group or a carboxyl group as a substituent. Examples of the chain hydrocarbon polymer having an unsaturated group include butadiene, isoprene,
Examples thereof include oligomers, polymers and copolymers such as 1,3 pentadiene. These chain hydrocarbon polymers having an unsaturated group may be used alone or in combination of two or more. The chain hydrocarbon polymer having an unsaturated group does not necessarily have to be a pure substance, and impurities such as a solvent mixed during the production thereof are allowed within a common sense.

Examples of the substance that promotes the oxygen absorption of the main agent used in the present invention include metal salts and radical initiators that promote the oxidation of organic compounds. As the metal salt, transition metal salts such as Cu, Fe, Co, Ni, Cr and Mn are preferable, and as the transition metal salt, for example, unsaturated fatty acid metal salt is preferably used.

In the present invention, when the main agent and the oxygen absorption promoting substance are liquid substances, it is preferable to support them.
As the carrier substance, natural pulp, paper or synthetic paper made of synthetic pulp, non-woven fabric, porous film, silica gel, alumina, activated carbon, synthetic zeolite such as molecular sieves, mordenite, natural zeolite such as erionite,
Examples include clay minerals such as pearlite and activated clay. It is also a practical use method to select a carrier substance to be used as a dehumidifying agent and to make the carrier have a dehumidifying ability. Further, as the carrier, the core material directly carries the liquid main component and the oxygen absorption promoting substance. You can also

The proportion of each component in the oxygen absorbent is appropriately selected depending on the type of substance used, but 0.01 to 40 parts by weight, preferably 0.1 to 10 parts by weight of the oxidation promoting substance relative to 100 parts by weight of the main agent. Parts by weight and the carrier material is
It is in the range of 1 to 5000 parts by weight, preferably 10 to 1000 parts by weight.

The oxygen absorbent, the dehumidifying agent and the acidic absorbent used in the present invention may be mixed and used, or may be used separately in different states. These are appropriately used in the form of powder, granules, tablets, sheets and the like. These may be added directly to the core material without being wrapped with a packaging material, but for ease of handling, they are usually gas barriers, for example, as a package packaged with a breathable packaging material based on paper or nonwoven fabric. It is enclosed in a sex container. The form of the package is not particularly limited, but a pouch, a sheet, or a blister-wrapped form is selected according to the purpose.

The dehumidifying agent used in the present invention includes paper made of natural pulp and synthetic pulp, synthetic paper, silica gel,
Alumina, activated carbon, zeolite, perlite, activated clay, quick lime, barium oxide, calcium chloride, barium bromide, calcium sulfate, magnesium chloride, magnesium oxide, magnesium sulfate, aluminum sulfate, sodium sulfate, sodium carbonate, potassium carbonate, zinc chloride, etc. Is exemplified.

The acidic gas absorbent used in the present invention may be any substance capable of absorbing or adsorbing the acidic gas generated from the reaction of the main agent or the core material and the acidic gas penetrating into the gas barrier closed container, For example, oxides, hydroxides, carbonates, organic acid salts and organic amines of alkali metals or alkaline earth metals are used. It is also possible to select an acidic gas absorbent as the above-mentioned carrier substance or dehumidifying agent and to make it function, and in this case, it is not necessary to add the acidic gas absorbent again.

Examples of the core material used in the present invention include continuous foams of plastics such as polyurethane and polystyrene, silica, diatomaceous earth, perlite, magnesium carbonate,
Examples include inorganic fine powders such as calcium silicate, porous molded plates such as calcium silicate plates and asbestos plates, and fibrous substances such as glass fibers, ceramic fibers, and polyester fibers. Among them, silica powder or polyurethane continuous foam is preferable. One kind of these core materials may be used, or a plurality of kinds may be used if necessary.

The gas barrier airtight container used in the present invention is at least one kind of a film obtained by vapor-depositing a metal foil such as aluminum or a metal foil such as polyvinylidene chloride, polyvinyl alcohol, polyester, polypropylene, polyamide, polyethylene, etc., or silicon oxide. A laminate of more than one layer is used. A heat-sealable resin such as polyethylene or polypropylene is used as the innermost layer sealant material.

The amounts of the oxygen absorbent, the dehumidifying agent and the acid gas absorbent used are appropriately selected depending on the gas barrier performance of the gas barrier closed container and the type of the core material. The oxygen absorbent is an amount capable of absorbing at least oxygen in the space volume in the gas barrier closed container and oxygen invading the gas barrier closed container, and is 0.1 to 100 parts by weight of the core material.
10 parts by weight, preferably 0.5-5 parts by weight are used. Further, the dehumidifying agent is an amount capable of absorbing at least the water in the space volume in the gas barrier closed container and the water entering the gas barrier closed container.
0.5 to 50 parts by weight, preferably 1 to 100 parts by weight
20 parts by weight are used. The amount of acid gas absorbent can absorb at least the space gas in the gas barrier closed container, the acid gas entering the gas barrier closed container and the acid gas generated from the oxygen absorbent or core material. Is 0.5 to 20 with respect to 100 parts by weight of the core material.
Parts by weight, preferably 1 to 10 parts by weight are used.

[0021]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention. The present invention is not limited to the embodiments. The thermal conductivity was measured using Showa Denko Co., Ltd. QTM type thermal conductivity meter at 13 ° C and 35 ° C.
The thermal conductivity was measured at the temperature difference between and.

Example 1 To a mixture of 1 g of soybean oil and 0.2 g of cobalt naphthenate, 3.5 g of zeolite was added, mixed with a blender and allowed to stand at 25 ° C. for 10 minutes to obtain a fluid granular material. . Obtained powder and granules 4.7 g and quick lime 2.5
g and 1.0 g of slaked lime were mixed. This is a getter. 5 parts by weight of the getter was filled in a small bag made of polyethylene terephthalate / polypropylene having a plurality of air-permeable pores, the opening was heat-sealed, and a getter packaging bag was obtained by using dried perlite powder (average particles) as a core material. (3 micron diameter) 100 parts by weight, and put in a barrier container made of stretched polypropylene / aluminum-deposited polyethylene terephthalate / polyethylene, and 0.1 torr in a vacuum packaging device equipped with a heat-sealing device.
While evacuating to a vacuum degree of r, the opening of the bag is heat-sealed and sealed, and the size is 300 × 300 mm and the thickness is 20 m.
m vacuum insulation was obtained. This vacuum insulation material is 40 ℃, 95
Table 1 shows the results of measuring the thermal conductivity after leaving it in the atmosphere of% RH for 90 days.

(Examples 2 to 10) A vacuum heat insulating material having the structure shown in Table 1 was obtained in the same manner as in Example 1, and the results of measuring the thermal conductivity are shown in Table 1.

(Comparative Examples 1 to 5) Vacuum heat insulating materials having the constitutions shown in Table 2 were obtained in the same manner as in Example 1 and the results of measuring the thermal conductivity are shown in Table 2. As apparent from Tables 1 and 2, 40
When left in an atmosphere of 90 ° C. and 95% RH for 90 days, the change in the thermal conductivity of the vacuum heat insulating material in which the oxygen absorbent of the present invention is arranged or added is slight, which is an excellent effect on the deterioration of the heat insulating performance. It is clear that

Table 1 shows Examples 1 to 13.

[Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Main ingredient Soybean oil Tall oil and fat Soybean oil Tall oil and fat Sesame oil 0.61 Fatty acid 0.61 0.61 Fatty acid 0.61 0.05 Oxygen absorption Naphthenic acid Co Naphthenic acid Co tall oil and fat Thor oil and fat Thor oil and fat promoting substance 0.12 0.12 Fatty acid Co 0.12 Fatty acid Co 0.02 Fatty acid Mn 0.02 Carrier material Zeolite Zeolite Zeolite Zeolite Aluminum oxide 2.1 2.1 2.1 0.9 0.5 Dehumidifying agent Quick lime Quick lime Quick lime Zeolite Zeolite 1.5 1.5 1.5 5.0 0.5 Acid gas Slaked lime Slaked lime Slaked lime Quick lime Quick lime absorbent 0.61 0.61 0.61 6.5 0.5 Ghetter wrapping Pouch wrap Pouch wrap Pouch wrap Pouch wrap Pouch wrap Core material Perlite Perlite Perlite Polyurethane Polyurethane Fine silica 100 100 100 100 100 Initial thermal conductivity 0.005 0.005 0.005 0.005 0.005 40 ° C, 95% RH 90 days left 0.006 0.006 0.006 0.006 0.006 Thermal conductivity unit: Kcal / m ． h. Unit of main agent etc .: parts by weight Polyurethane: continuous foam of polyurethane Table 1 Continuation Example 6 Example 7 Example 8 Example 9 Example 10 Main agent Cottonseed oil Linseed oil Oleic acid Linoleic acid Linolenic acid 0.05 0.05 0.61 0.61 0.61 Oxygen absorption Naphthenic acid Co Naphthenic acid Co Octylic acid Co Octylic acid Mn Oleic acid Fe promoting substance 0.001 0.0002 0.12 0.12 0.12 Support material Zeolite Zeolite Zeolite Zeolite 0.5 0.5 2.1 2.1 2.1 Dehumidifying agent Zeolite Zeolite Activated carbon Ca 0.5 0.5 30 1.5 1.5 Acid gas Quick lime Quick lime Oxidized Mg Chloride Mg Absorbed sodium hydroxide 0.5 0.5 0.61 20 0.61 Getta packaging Pouch packaging Pouch packaging Pouch packaging Pouch packaging Pouch packaging Core material Polyurethane Polyurethane Perlite Perlite Perlite 100 100 100 100 100 Initial thermal conductivity 0.005 0.005 0.007 0.005 0.005 40 ℃, 95% RH 90 days after leaving 0. 006 0.007 0.008 0.007 0.007 Unit of thermal conductivity: Kcal / m. h. Unit of main ingredient: parts by weight Table 1 continued Example 11 Example 12 Example 13 Main ingredient Soybean oil / Liquid isoprene Soybean oil / Liquid soybean oil Soybean oil 0.61 0.61 0.61 Oxygen absorption Co Naphthenic acid Co Naphthenic acid Co Naphthenic acid Co accelerator 0.12 0.12 0.12 Carrier material Geolite Zeolite Geolite 2.1 2.1 2.1 Dehumidifying agent Quick lime Quick lime Quick lime 1.5 1.5 1.5 Acid gas Slaked lime Slaked lime Slaked lime Absorber 0.61 0.61 0.61 Getta packaging Small bag packaging Small bag packaging Core material pearl light pearl light pearl light 100 100 100 Initial heat conduction Rate 0.005 0.005 0.005 40 ° C, 95% RH 90 days after storage 0.006 0.006 0.006 Thermal conductivity unit: Kcal / m. h. ℃ Unit of main agent: parts by weight

Table 2 shows Comparative Examples 1 to 5.

[Table 2] Table 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Main ingredient None Iron powder None None None None 5 Oxygen absorption ──── ──── ──────── ─── ─ Accelerating substance Carrier substance ──── ──── ──── ──── ──── Dehumidifying agent ──── ──── Silica gel 5 ──── ──── Acidic gas ──── ──── ──── ──── ──── Absorbent getter packaging None Pouch packaging Pouch packaging None None Core material pearlite pearlite pearlite fine silica silica 100 100 100 100 100 Initial heat conduction Rate 0.004 0.004 0.005 0.005 0.005 40 ° C, 95% RH 90 days after storage 0.038 0.016 0.019 0.030 0.026 Thermal conductivity unit: Kcal / m. h. ℃ Units such as core material: parts by weight Iron powder of Comparative Example 2: specific surface area 2.5 m ² / g average particle size 120 microns

[0027]

INDUSTRIAL APPLICABILITY The present invention is a vacuum container composed of a gas-barrier closed container, a core material for maintaining shape and preventing convection, an oxygen absorbent that does not require water to absorb oxygen, a dehumidifying agent and an acidic gas absorbent. The heat insulating material absorbs the gas that gradually enters the gas barrier closed container and the gas that is gradually generated from the filled heat insulating material, and maintains the initial degree of vacuum in the gas barrier closed container as much as possible. It is possible to maintain the initial insulation performance of, and its practical value is great.

Claims (3)

[Claims] 1. A vacuum heat insulating material comprising a gas-barrier closed container, a core material, an oxygen absorbent that does not require moisture to absorb oxygen, a dehumidifying agent, and an acidic gas absorbent. 2. An oxygen absorbent which does not require water for absorbing oxygen, which is mainly composed of an unsaturated fatty acid compound and / or a chain hydrocarbon polymer having an unsaturated group and which contains an oxygen absorption promoter. The vacuum heat insulating material according to claim 1. 3. The acidic gas absorbent is at least one selected from oxides, hydroxides, carbonates, organic acid salts and organic amines of alkali metals or alkaline earth metals. Vacuum insulation.