JP2015081677A - Vacuum insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum insulation material capable of reducing a heat bridge of an exterior material part.SOLUTION: A vacuum insulation material is formed by interposing a core material and a gas adsorption agent between a pair of gas barrier exterior materials, depressurizing the inside and sealing them. At least one of the pair of gas barrier exterior materials comprises a laminate of an electrolytic metal foil and a plastic.

Description

  The present invention relates to a vacuum heat insulating material. Especially this invention relates to the vacuum heat insulating material which can reduce effectively the heat bridge of an exterior material part.

  The vacuum heat insulating material is formed by vacuum-packing a core material and a gas adsorbent with a gas barrier outer packaging material, and suppresses thermal conductivity by keeping the inside vacuum. Vacuum heat insulating materials are used for electrical products such as freezers, refrigerators, heat storages, vending machines, and wall materials for houses because of their low thermal conductivity.

  The gas barrier exterior material is composed of a laminate of an aluminum foil and a plastic, but since aluminum has a high thermal conductivity of 237 W / m · K, vacuum insulation using the above-described laminate as an exterior material. There was a problem that the material had a large heat bridge through which heat from the surroundings traveled around the exterior material part.

  As a method for reducing the heat bridge of such a vacuum heat insulating material, there is a method in which a laminated body of an aluminum vapor deposition layer and a plastic is used for one of the exterior materials (see, for example, Patent Document 1). In addition, vacuum insulation using a metal foil (iron, lead, tin, stainless steel, etc.) with a low thermal conductivity instead of an aluminum foil as a gas barrier layer in order to reduce the heat conductivity while maintaining gas barrier properties. The material is reported (for example, see Patent Document 2).

Japanese Patent Laid-Open No. Sho 63-1255577 Japanese Patent Laid-Open No. 9-137889

  However, since the aluminum vapor deposition layer disclosed in Patent Document 1 has low gas barrier properties, it is difficult to prevent the intrusion of gas from the outside, and it is difficult to maintain the degree of vacuum inside the vacuum heat insulating material for a long time.

  Since the metal foil disclosed in Patent Document 2 is produced by rolling, the metal foil such as iron, lead, tin, and stainless steel has a thickness of 20 μm (for example, paragraph “0010” in Patent Document 2). For this reason, a heat bridge will become a big problem. In addition, the metal foil disclosed in Patent Document 2 has a problem that workability is poor due to its thickness, it is hard to bend an excessive heat seal portion that becomes a blockage factor of the flow path when encapsulating urethane, and has poor handling properties. It was.

  Therefore, this invention is made | formed in view of the said situation, and it aims at providing the vacuum heat insulating material which can reduce the heat bridge of an exterior material part.

  Another object of the present invention is to provide a vacuum heat insulating material having excellent gas barrier properties and / or workability.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above-mentioned problems can be solved by using an electrolytic metal foil as an exterior material, and have completed the present invention.

  That is, the above-mentioned objects are a vacuum heat insulating material that includes a core material and a gas adsorbent so as to be sandwiched between a pair of exterior materials having a gas barrier property, and is sealed by reducing the pressure inside. This is achieved by a vacuum heat insulating material in which at least one of the exterior materials having gas barrier properties is made of a laminate of electrolytic metal foil and plastic.

  ADVANTAGE OF THE INVENTION According to this invention, the vacuum heat insulating material which can reduce effectively the heat bridge of an exterior material part can be provided. Moreover, the vacuum heat insulating material of this invention is excellent in gas barrier property and workability.

It is a schematic cross section which shows an example of the vacuum heat insulating material of this invention.

  The present invention is a vacuum heat insulating material that includes a core material and a gas adsorbent so as to be sandwiched from both sides by a pair of outer packaging materials having gas barrier properties, and is sealed by reducing the pressure inside. It is related with the vacuum heat insulating material in which at least one of the exterior material which has this consists of a laminated body of electrolytic metal foil and a plastic. The present invention is characterized in that an electrolytic metal foil is used for the exterior material of the vacuum heat insulating material. With such a configuration, the heat bridge of the exterior material can be effectively reduced. Here, the mechanism for exerting the above-described effects by the configuration of the present invention is presumed as follows. The present invention is not limited to the following.

  That is, the exterior material usually has a laminated structure of a metal layer having a gas barrier property and a plastic film, and among these, the thickness of the metal layer is one of the main causes for causing a heat bridge. Specifically, in a thick metal layer, the amount of heat that travels through the metal layer and through the periphery (surrounding) of the exterior material is large, so that the heat bridge becomes large. In other words, the thickness of the metal layer and the occurrence of heat bridge have a positive correlation. On the other hand, in the present invention, the electrolytic metal foil is very thin and excellent in gas barrier properties, that is, can maintain the degree of vacuum inside the vacuum heat insulating material for a long time. For this reason, by using such a thin (thin thickness) electrolytic metal foil, the amount of heat that travels from the surroundings through the exterior material can be kept low. Therefore, heat bridge can be effectively suppressed and prevented by using the exterior material according to the present invention. In particular, when the electrolytic metal foil contains nickel or is composed of nickel (a nickel foil), the high thermal resistance (low thermal conductivity) can more efficiently suppress and prevent the heat bridge problem. Furthermore, since the surface of the electrolytic foil is finer than that of the rolled foil, the effect of improving the adhesion can be expected by laminating with a plastic film or the like.

  Generally, when manufacturing a vacuum heat insulating material, the core material and the gas adsorbent are encapsulated with a pair of exterior materials having a gas barrier property, and then the interior is decompressed and sealed. The parts are joined together to form a convex joint (seal part). The joint is bent at the time of product. For example, as described in Patent Document 2, when the thickness of the exterior material is large, the flexibility of the joint is low, so that the core material and the gas adsorbent are stored. It is difficult or impossible to bend so as to be in close contact with the vacuum heat insulating material main body. On the other hand, the electrolytic metal foil according to the present invention can be easily formed into a thin film and has excellent gas barrier properties even if it is thin. For this reason, the exterior material which concerns on this invention can be bend | folded to the vacuum heat insulating body main-body part side in the state which joined the contact part easily (it is excellent in workability). Therefore, the vacuum heat insulating material of this invention is excellent also in gas barrier property and workability.

  Therefore, the vacuum heat insulating material of the present invention has a low thermal conductivity, can effectively suppress the generation of heat bridges, and is excellent in gas barrier properties and workability. For this reason, the vacuum heat insulating material of this invention is useful as vacuum heat insulating materials, such as a refrigerator-freezer.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  In the present specification, “X to Y” indicating a range means “X or more and Y or less”, and “weight” and “mass”, “wt%” and “mass%”, “part by weight” and “ “Part by mass” is treated as a synonym. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

[Vacuum insulation]
FIG. 1 is a schematic cross-sectional view showing an example of the vacuum heat insulating material of the present invention. As shown in FIG. 1A, the vacuum heat insulating material 1 has a structure in which a core material 6 and a gas adsorbent 7 are included so as to be sandwiched by two exterior materials 2 from both sides. Here, the exterior material 2 is composed of a laminate (laminated film) of the electrolytic metal foil 4 and the plastic films 3 and 5. As described above, since the electrolytic metal foil is thin and excellent in gas barrier properties, the amount of heat that flows from the surroundings through the exterior material 2 can be kept low. For this reason, a heat bridge can be efficiently suppressed and prevented by using the exterior material which concerns on this invention.

  Here, the vacuum heat insulating material 1 produces a three-sided bag-shaped exterior material by sealing (for example, heat sealing) the periphery of the laminate, and the core material 6 and the gas adsorbent in the exterior material 2. In this state, the inside is decompressed to seal the opening (for example, heat seal). For this reason, as shown in FIG. 1, there are joint portions (seal portions) 8 in which the exterior materials (laminates) are joined to each other (edge portions) around the exterior material (laminate) 2. As shown in FIG. 1B, the joint portion 8 is bent toward the vacuum heat insulating material main body to become a vacuum heat insulating material product. As described above, the exterior material (particularly, electrolytic metal foil) can be easily formed into a thin film and has excellent gas barrier properties even if it is thin, so that the joint can be easily adhered to the vacuum heat insulating material body. Therefore, according to the present invention, even when the joint is folded, heat insulation is effectively suppressed and prevented by heat bridges that flow heat along the surface of the vacuum heat insulating material. High vacuum insulation material can be provided.

  Hereinafter, each member of the vacuum heat insulating material of the present invention will be described. In addition, since this invention is characterized by using electrolytic metal foil for an exterior material, about the other members, the same member as the past can be used, and it is not limited to the following form.

(Exterior material)
The exterior material is composed of a laminate of electrolytic metal foil and plastic. Here, a vacuum heat insulating material is composed of two exterior materials, and at least one of the two materials may be a laminate of electrolytic metal foil and plastic, but both of them are electrolytic metal foil and plastic. It is preferable that it is comprised from the laminated body. The outer packaging material that is not a laminate of the electrolytic metal foil and the plastic in the former case is not particularly limited. For example, at least aluminum, iron, gold, silver, copper, nickel, SUS, tin, titanium, platinum, lead, cobalt, Metal foils such as zinc and carbon steel and / or at least two alloy foils thereof, and deposited films such as aluminum, nickel, cobalt, zinc, gold, silver, copper, silicon oxide, alumina, magnesium oxide, and titanium oxide, and / or Or the laminated body of those at least 2 sorts of alloy vapor deposition films, and a plastic etc. are mentioned.

  Moreover, in FIG. 1, although the electrolytic metal foil 4 and the plastic films 3 and 5 are each shown by the single layer (one layer) form, the electrolytic metal foil and the plastic film which comprise an exterior material are each a single layer. It may exist in a form or may exist in two or more kinds of laminated forms. In the latter case, the electrolytic metal foil and the plastic film preferably have a structure in which two or more layers are laminated. Moreover, any form may be sufficient as the lamination | stacking form of electrolytic metal foil and a plastic film, but when adhesiveness (fusion property), a surface protection effect, etc. are considered, outermost layer and innermost layer are plastic films. Is preferred. That is, the exterior material is preferably in the form of a laminate of plastic film-electrolytic metal foil-plastic film from the outside.

  In the present invention, the electrolytic metal foil may be a single layer or a laminate of two or more types. The composition of the electrolytic metal foil may be composed of any material as long as it is a metal foil produced by electrolysis, and is not particularly limited. Specifically, nickel, zinc, iron, aluminum, copper, etc. are mentioned as a material which comprises electrolytic metal foil. The material may be an electrolytic metal foil composed of one kind of metal, or an electrolytic alloy foil composed of an alloy of two or more metals. Preferably, the electrolytic metal foil includes nickel. That is, the electrolytic metal foil is preferably a nickel foil or an alloy foil containing nickel. Alternatively, the electrolytic metal foil preferably contains a copper alloy. That is, the electrolytic metal foil is also preferably an alloy foil containing copper. In addition, when using metals with high heat conductivity, such as copper, combining with a metal with low heat conductivity is preferable. Thereby, the thermal conductivity of the obtained electrolytic metal foil can be reduced, that is, the problem of heat bridge can be more effectively eliminated, and the heat insulation can be further improved. Considering the above points, the electrolytic metal foil is preferably a nickel foil, a copper-nickel alloy foil, or a copper-zinc alloy foil, and more preferably a nickel foil or a copper-nickel alloy foil. If the electrolytic metal foil is an alloy foil, the electrolytic metal foil can be made from an alloy of two or more metals.

  The alloy composition when the electrolytic metal foil is an alloy foil is not particularly limited, and is appropriately selected in consideration of desired thermal conductivity, ease of control of the thickness of the metal foil, thermal resistance, and the like. Specifically, when the electrolytic metal foil is a nickel alloy foil (alloy foil containing nickel), nickel is 1% by weight or more with respect to the electrolytic metal foil (total weight of metals constituting the metal foil). It is preferable that it is 10% by weight or more. In addition, although the upper limit of nickel composition is not specifically limited, It is preferable that it is 50 weight% or less with respect to electrolytic metal foil (total weight of the metal which comprises metal foil). Moreover, when electrolytic metal foil is copper alloy foil (alloy foil containing copper), copper is 99 weight% or less with respect to electrolytic metal foil (total weight of the metal which comprises metal foil). Is preferable, and it is more preferable that it is 90 weight% or less. In addition, although the minimum of a copper composition is not specifically limited, It is preferable that it is 1 weight% or more with respect to electrolytic metal foil (total weight of the metal which comprises metal foil). With such a composition, the electrolytic metal foil can exhibit a sufficiently low thermal conductivity, a sufficiently high thermal resistance (that is, excellent heat insulation) and a high gas barrier property.

  Moreover, the thickness of the electrolytic metal foil is not particularly limited. Specifically, the thickness (d) of the electrolytic metal foil is preferably 1 to 10 μm, more preferably 3 to 8 μm. If the thickness of the foil is less than 1 μm, sufficient gas barrier properties may not be ensured. On the other hand, when the thickness exceeds 10 μm, problems such as low thermal resistance and poor workability such as flexibility may occur. Since the electrolytic metal foil having such a thin thickness is excellent in workability, the joint portion of the exterior material can be easily adhered to the vacuum heat insulating material body. Moreover, if it is the said thickness, an exterior material can suppress and prevent the heat bridge where heat flows along a vacuum heat insulating material surface more effectively, can improve heat insulation performance, and is excellent also in gas barrier property. In addition, in this specification, the thickness of electrolytic metal foil intends the maximum thickness of electrolytic metal foil.

  The exterior material according to the present invention preferably has low thermal conductivity in consideration of heat insulation. For this reason, it is preferable that the electrolytic metal foil also has a low thermal conductivity. Specifically, the thermal conductivity (λ) of the electrolytic metal foil is preferably 130 W / m · K or less, more preferably 100 W / m · K or less. When the thermal conductivity is greater than 130 W / m · K, there is a possibility that the effect of suppressing the heat bridge is not sufficient as compared with the current rolled aluminum foil. In addition, since the lower the thermal conductivity of the electrolytic metal foil, the lower the better, the lower limit is not particularly limited, but usually 10 W / m · K or more is sufficient, and 20 W / m · K or more may be sufficient. If it is such heat conductivity, an exterior material is excellent in heat insulation. In addition, although the heat conductivity of electrolytic metal foil can be measured by a well-known measuring method, in this specification, "thermal conductivity of electrolytic metal foil" is measured in the following Example.

  As described above, the problem of heat bridge is solved by using the exterior material according to the present invention. Considering the effect of suppressing the heat bridge, the exterior material is preferably thin and has low thermal conductivity. Considering the above points, it is preferable that the thermal resistance of the electrolytic metal foil is high. For example, the electrolytic metal foil preferably has a thermal resistance (R) of 650 K / W or higher, and a thermal resistance (R of 750 K / W or higher). ), More preferably a thermal resistance (R) of 1000 K / W or higher, even more preferably a thermal resistance (R) of 1500 K / W or higher. In addition, since it is so preferable that the thermal resistance of electrolytic metal foil is high, an upper limit is not specifically limited, Usually, 10,000 K / W or less is enough, and it may be 8,000 K / W or less. A vacuum heat insulating material using an electrolytic metal foil (and hence an exterior material) having a thermal resistance of 650 K / W or more and a thickness of 10 μm or less, while maintaining good workability as compared with a conventional aluminum foil, Generation of heat bridge can be more effectively suppressed / prevented. In this specification, “thermal resistance” refers to the thermal resistance perpendicular to the thickness direction with respect to the metal foil per unit area, and the thermal resistance (R) (K / W) is the value of the electrolytic metal foil. It is measured from the thickness (d) and the thermal conductivity (λ), and specifically calculated by the following formula.

The exterior material according to the present invention is preferably excellent in gas barrier properties. For this reason, it is preferable that the electrolytic metal foil is also excellent in gas barrier properties. Specifically, the water vapor permeability of the electrolytic metal foil is preferably 1 × 10 ⁻³ (g / m ² · day) or less, and more preferably 5 × 10 ⁻⁴ (g / m ² · day) or less. preferable. When the water vapor permeability is higher than 1 × 10 ⁻³ (g / m ² · day), the gas barrier property of the exterior material is poor, and the degree of vacuum inside the vacuum heat insulating material may not be maintained for a long time. In addition, since the water vapor permeability of electrolytic metal foil is so low that it is so preferable, a minimum is not specifically limited, However Usually 1 * 10 < ^-7 > (g / m < ² > * day) or more is enough.

  The method for producing an electrolytic metal foil according to the present invention is not particularly limited, and a known metal electrolysis method (a method of electrodepositing metal on a rotating drum) can be applied in the same manner or appropriately modified. Alternatively, a commercially available electrolytic metal foil may be used.

  Further, the method for producing the electrolytic metal foil in the case where the electrolytic metal foil according to the present invention is an electrolytic alloy foil is also not particularly limited, but is usually produced by an alloying treatment by heat treatment. Preferably, (a) on one or both sides of an electrolytic metal foil (for example, electrolytic copper foil) (hereinafter also referred to as “raw metal foil”) composed of a metal (for example, copper) constituting the alloy, other than the above metal A metal (for example, nickel) (hereinafter, also referred to as “alloyed metal”) constituting the alloy of the above alloy is further laminated by electrolysis, followed by a heating (alloying) treatment, and (b) an alloy having a desired composition. Examples of the method include a method of forming into a foil shape after manufacturing by alloying treatment. Of these, the method (a) is preferred. Hereinafter, although the said preferable form (method of (a)) is demonstrated, this invention is not limited to the following form.

  In the above (a), the raw metal foil formed by electrolysis is thin and excellent in gas barrier properties. For this reason, the electrolytic metal foil obtained by laminating a metal on the raw metal foil and alloying it can suppress the amount of heat that flows from the surroundings through the exterior material portion due to its thinness. For this reason, the exterior material using such electrolytic metal foil can suppress and prevent the heat bridge of a vacuum heat insulating material efficiently. For the same reason, since the exterior material is thin, it is excellent in workability (flexibility), and it is easy to bend the joint that obstructs the urethane encapsulation, so that the joint is easily adhered to the vacuum heat insulating material body. be able to. Here, the production method of the electrolytic metal foil is not particularly limited, and a known method of electrodepositing metal on a rotating drum can be used. The electrolytic metal foil may be a metal foil made of one kind of metal, or a metal foil made of a mixture of two or more kinds or an alloy of two or more kinds of metals. Alternatively, a commercially available electrolytic metal foil may be used.

  In general, a method for producing a metal foil is largely divided into a rolling method in which an electric metal (for example, electrolytic copper) is repeatedly rolled and annealed to form a foil, and the electrolytic method. Whether the copper alloy foil is manufactured by the rolling method or the electrolytic method can be identified by the following method. That is, the copper alloy foil manufactured by the rolling method has large crystal grains and is stretched in the surface direction of the foil by the rolling operation, whereas the copper alloy foil manufactured by the electrolytic method has crystal grains. It is dense and grows in the thickness direction of the foil. Moreover, the electrolytic foil has a larger surface roughness than the rolled foil due to its manufacturing process. Preferably, the surface roughness (Rz) of the electrolytic foil is 0.1 μm to 3 μm, more preferably 0.5 μm to 2.5 μm, and still more preferably 0.7 μm to 2 μm.

  The alloyed metal may be laminated on at least one surface of the raw metal foil, but is preferably laminated on both surfaces. Thereby, since the alloying process of the next process can be performed uniformly in the thickness direction of the raw metal foil, the homogenization of the electrolytic metal foil composition can be further improved. As described above, in consideration of the effect of suppressing heat bridge and workability, the electrolytic metal foil is preferably thin, and specifically, the total thickness of the raw metal foil and the alloyed metal is 10 μm or less. Is preferred. From the viewpoint of ease of production, cost, etc., the raw metal foil is preferably 99% by weight or less, more preferably 90% by weight or less, based on the alloyed metal. .

  Moreover, the lamination | stacking method of an alloying metal to raw material metal foil is not restrict | limited in particular. For example, electrolytic plating or the like can be mentioned, and electrolytic plating is preferably used in consideration of thinning of the electrolytic metal foil. The laminating operation may be performed once or repeatedly. For this reason, (a) an operation of laminating one kind of alloyed metal or a mixture of two or more kinds of alloyed metal on the raw material metal foil, and (a) producing a raw material metal foil made of one or more kinds of metals. And (e) an operation of repeatedly performing the operations (a) and / or (b) above, and (e) an operation of (a) to (c) above. Any form such as a combination can be applied.

  Moreover, the heating (alloying) treatment after laminating the alloying metal on the raw metal foil is not particularly limited as long as the alloying treatment can sufficiently proceed. For example, the heating (alloying) temperature is preferably 400 to 1000 ° C, more preferably 600 to 900 ° C. When the heating temperature is lower than 400 ° C., the temperature is low and there is a possibility that the alloy is not sufficiently formed. Further, when the temperature is higher than 1000 ° C., it becomes close to the melting point, which may make it difficult to alloy the foil while maintaining the shape of the foil. Under such conditions, the raw metal foil and the alloyed metal are sufficiently alloyed, and an electrolytic metal foil having a desired composition can be efficiently produced. The heating (alloying) treatment may be performed in any atmosphere, but in order to prevent oxidation of the metal surface, reduction or vacuum or an inert gas (for example, nitrogen gas, argon gas, helium gas, Hydrogen gas, ammonia gas, etc.) are preferably performed under an atmosphere.

  The electrolytic metal foil thus obtained is laminated with a plastic film to obtain the exterior material according to the present invention. Here, the plastic film may be a single layer or a laminate of two or more. Further, the composition of the plastic film is not particularly limited, but usually, the plastic film (the plastic film 5 in FIG. 1) on the inner side (the side where the core material and the gas adsorbent are accommodated) than the electrolytic metal foil is thermally weldable. It is preferable that the plastic film (the plastic film 3 in FIG. 1) on the outer side (the side in contact with the outside air) than the electrolytic metal foil is a film having a surface protective effect (surface protective film).

  Here, a heat welding film will not be specifically limited if it can be adhere | attached by a normal sealing method (for example, heat sealing). Examples of the material constituting the heat welding film include polyolefins such as low density polyethylene, linear low density polyethylene, high density polyethylene, and polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene- Acrylic ester copolymers, ethylene-acrylic ester copolymers, thermoplastic resins such as polyacrylonitrile, and the like can be mentioned. In addition, the said material may be used independently or 2 or more types of mixtures may be sufficient as it. Further, the heat welding film may be a single layer or a laminated form of two or more layers. In the latter case, each layer may have a similar composition or a different composition.

  The thickness of the heat welding film is not particularly limited, and may be the same thickness as a known thickness. Specifically, the thickness of the heat welding film is preferably 10 to 100 μm. If it is thinner than 10 μm, sufficient adhesion strength cannot be obtained during heat sealing, and if it is thicker than 100 μm, workability such as flexibility is deteriorated. In addition, when the heat welding film has a laminated structure of two or more layers, the thickness of the heat welding film means the total thickness. In this case, the thickness of each layer may be the same or different.

  Further, the surface protective film is not particularly limited, and the same material as that usually used as the surface protective film of the exterior material can be used. Examples of the material constituting the surface protective film include polyamide (nylon) (PA) such as nylon-6 and nylon-66, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT). Polyester such as Polyethylene, Polyethylene (PE), Polypropylene (PP), Polystyrene such as Polystyrene (PS), Polyimide, Polyacrylate, Polyvinyl Chloride (PVC), Polyvinylidene Chloride (PVDC), Ethylene Vinyl Alcohol Copolymer (EVOH) , Polyvinyl alcohol resin (PVA), polycarbonate (PC), polyether sulfone (PES), polymethyl methacrylate (PMMA), polyacrylonitrile resin (PAN), and the like. These films may be used with various known additives and stabilizers such as antistatic agents, UV inhibitors, plasticizers and lubricants. In addition, the said material may be used independently or 2 or more types of mixtures may be sufficient as it. Further, the surface protective film may be a single layer or a laminated form of two or more layers. In the latter case, each layer may have a similar composition or a different composition.

  The thickness of the surface protective film is not particularly limited, and may be the same thickness as a known thickness. Specifically, the thickness of the surface protective film is preferably 10 to 100 μm. When the thickness is less than 10 μm, the barrier layer is not sufficiently protected and may cause cracks. Moreover, when thicker than 100 micrometers, workability, such as a flexibility, may worsen like a heat welding film. In addition, when the surface protection film has a laminated structure of two or more layers, the above thickness means the total thickness. In this case, the thickness of each layer may be the same or different.

  The thickness of the exterior material is not particularly limited. Specifically, the thickness of the exterior material is preferably 20 to 210 μm. If the exterior material is thin as described above, the heat bridge can be more effectively suppressed and prevented to improve the heat insulation performance, and the gas barrier property and workability are also excellent.

  Moreover, it is preferable that the exterior material which concerns on this invention has low heat conductivity when heat insulation is considered. For this reason, it is preferable that the vacuum heat insulating material (exterior material) also has a low thermal conductivity. Specifically, the thermal conductivity (λ) of the vacuum heat insulating material (exterior material) is preferably 0.01 W / m · K or less, more preferably 0.005 W / m · K or less. If it is such heat conductivity, a vacuum heat insulating material will be excellent in heat insulation. In addition, since the heat conductivity of a vacuum heat insulating material (exterior material) is so preferable that it is low, a minimum is not specifically limited, However, 0.0005 W / m * K or more is sufficient normally. Moreover, although the heat conductivity of a vacuum heat insulating material (exterior material) can be measured by a well-known measuring method, in this specification, "the heat conductivity of a vacuum heat insulating material (exterior material)" is measured in the following Example. The

  The method for producing the vacuum heat insulating material is not particularly limited, and a method similar to a known method or a method appropriately modified from a known method can be used. For example, (i) two exterior materials are prepared, one of the exterior materials (laminate film) is folded, and the heat-welded films located at the ends of the facing exterior materials are thermally welded together to form a bag-shaped exterior material A method of inserting a core material and a gas adsorbent into the exterior material and thermally welding the heat-welded films located at the opening of the bag-like laminate film under reduced pressure, (ii) heat-welded films Two package materials (laminate film) are arranged so as to oppose each other, and a bag-like package material is obtained by thermally welding the heat-welded films located at the end portions of the respective package materials. Examples of the method include inserting a core material and a gas adsorbent into the material and thermally welding the heat-welded films located near the opening of the bag-like laminate film under reduced pressure.

(Core material)
The core material that can be used in the present invention serves as a skeleton of the vacuum heat insulating material and forms a vacuum space. Here, the material of the core material is not particularly limited, and a known core material can be used. Specifically, inorganic fibers such as glass wool, rock wool, alumina fiber, metal fiber made of metal with low thermal conductivity; cellulose, cotton produced from synthetic fibers such as polyester, polyamide, acrylic, polyolefin, and wood pulp, Organic fibers such as natural fibers such as hemp, wool and silk, regenerated fibers such as rayon, semisynthetic fibers such as acetate, and the like. The core material may be used alone or a mixture of two or more. Of these, glass wool is preferred. The core material made of these materials has high elasticity of the fiber itself, low thermal conductivity of the fiber itself, and is industrially inexpensive.

(Gas adsorbent)
The gas adsorbent that can be used in the present invention adsorbs gas such as water vapor or air (oxygen, nitrogen) remaining or entering the sealed space of the vacuum heat insulating material. Here, it does not specifically limit as a gas adsorbent, A well-known gas adsorbent can be used. Specifically, chemical adsorption materials such as calcium oxide (quick lime) and magnesium oxide, physical adsorption materials such as zeolite, continuous urethane, lithium compound, copper ion exchange ZSM-5 type zeolite having chemical adsorption properties and physical adsorption properties, Examples thereof include molecular sieve 13X. The core material may be used alone or a mixture of two or more.

  As described above, the vacuum heat insulating material of the present invention has low thermal conductivity, can effectively suppress the generation of heat bridges, and is excellent in gas barrier properties and workability. Therefore, the vacuum heat insulating material of the present invention is suitable for equipment that needs to maintain heat insulating performance, such as a freezer, a refrigerator, a vending machine, a hot water supply container, a heat insulating material for buildings, a heat insulating material for automobiles, and a cold insulation / heat insulating box. Applicable to.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, “%” and “part” mean “% by weight” and “part by weight”, respectively.

Example 1
The electrolytic nickel foil 1 having a thickness of 6 μm was used for the gas barrier layer of the exterior material.

Example 2
Nickel was formed by electrolytic plating so that the copper ratio was 90% by weight on the electrolytic copper foil, to obtain a 10 μm thick copper-nickel laminated foil. Thereafter, heat treatment was performed at 800 ° C. for 60 minutes in an N ₂ atmosphere, thereby producing a copper-nickel alloy foil 1.

Example 3
A copper-nickel foil 2 was prepared in the same manner as in Example 1 except that the copper ratio of the copper-nickel laminated foil was changed to 80% by weight.

Example 4
A copper-nickel foil 3 was prepared in the same manner as in Example 3 except that the thickness of the copper-nickel laminated foil was 8 μm.

Example 5
A copper-nickel foil 4 was prepared in the same manner as in Example 1 except that electrolytic plating was performed on the electrolytic nickel foil such that the copper ratio was 55% by weight.

Example 6
A copper-zinc foil 1 was prepared in the same manner as in Example 1 except that zinc was electrolytically plated on the electrolytic copper foil so that the copper ratio was 65% by weight.

Comparative Example 1
Rolled aluminum foil (7 μm) was used.

Comparative Example 2
VM-PET in which an Al deposited film having a thickness of 50 nm was formed on a polyethylene terephthalate having a thickness of 12 μm was used.

Comparative Example 3
Rolled SUS foil (20 μm) was used.

  The following evaluation was performed about the metal foil and VM-PET produced above.

<Evaluation 1: Water vapor permeability>
The water vapor permeability (g / m ² · day) of the metal foils and VM-PETs prepared in Examples 1 to 6 and Comparative Examples 1 to 3 was measured according to the following method. That is, the water vapor permeability is measured at a temperature of 40 ° C. and a relative humidity of 90% RH using Aquatran (manufactured by MOCON) in accordance with ISO 15106-3. The results are shown in Table 1 below.

  Similarly, the metal foils and VM-PETs produced in Examples 1 to 5 and Comparative Examples 1 to 3 were overlapped by A4 size, and the flexibility was evaluated by folding back the inner side by 30 mm from the end for 4 sides. It was. The flexibility was evaluated as follows.

  The results are shown in Table 1 below.

  As shown in Table 1 above, Comparative Example 2 using an aluminum vapor deposition film as a gas barrier layer has a water vapor transmission rate as compared with Examples 1 to 6 and Comparative Examples 1 and 3 using other metal foils. It is high and it turns out that it is inferior to gas barrier property. Moreover, when a rolled SUS foil is used, it turns out that flexibility is bad and workability is inferior.

<Evaluation 2: Thermal conductivity and thermal resistance of metal foil>
About the metal foil produced in the said Examples 1-6 and the comparative example 1, the thermal diffusivity of the surface direction of copper alloy foil was measured using Thermowave Analyzer (made by Nissan Arc Co., Ltd.), and the specific heat of each copper alloy foil The thermal conductivity (W / m · K) is calculated from the density. Further, the thermal resistance (K / W) is calculated from the thermal conductivity and thickness of the copper alloy foil thus obtained. The results are shown in Table 2 below.

<Evaluation 3: Calculation of effective thermal conductivity of vacuum heat insulating material>
About the metal foil produced in the said Examples 1-6 and the comparative example 1, literature (M. Tenpierik, and H. Cauberg, Journal of Building Physics, Vol. 30, No.3-January 2007) and each metal foil. From the thermal conductivity and thickness, the effective thermal conductivity when the thermal conductivity of the central part of the vacuum heat insulating material (290 mm × 410 mm × t6 mm) is 1 mW / m · K (that is, the average thermal conductivity of the entire vacuum heat insulating material). And the heat bridge was evaluated.
The results are shown in Table 2 below.

  As shown in Table 2 below, by using the electrolytic metal foil and the electrolytic alloy foil of the present invention, the thermal resistance is improved as compared with the conventional rolled aluminum foil used for the barrier layer of the vacuum heat insulating material, and the influence of the heat bridge It has been shown that it is possible to suppress the above, and it is considered that excellent heat insulation can be exhibited.

<Evaluation 4: Thermal conductivity and heat bridge evaluation of vacuum heat insulating material>
Production Example 1
The nickel electrolytic foil 1 (thickness: 6 μm) of Example 1 above, a polyethylene terephthalate film (thickness: 12 μm) and polyamide (thickness: 25 μm) as a surface protective film, and a linear low-density polyethylene film as a heat welding film A laminate film was prepared by laminating with a dry laminate so as to be between the surface protective film (thickness: 50 μm) and the heat-welded film.

  A laminate of short fiber glass wool was used as a core material, and quicklime stored in a breathable packaging material was used as a gas adsorbent. Using the exterior material 1, the core material, and the gas adsorbent, a vacuum heat insulating material 1 having a width of 290 mm × a depth of 410 mm × a height of 6 mm was produced.

Production Example 2
A vacuum heat insulating material 2 was produced by the same method except that the size of the vacuum heat insulating material in Production Example 1 was 130 mm wide, 230 mm deep, and 6 mm high.

Production Comparative Example 1
A vacuum heat insulating material 3 was produced in the same manner except that the metal foil of Production Example 1 was a rolled aluminum foil (thickness: 7 μm).

Production Comparative Example 2
The vacuum heat insulating material 4 was produced by the same method except having made the size of the vacuum heat insulating material of the said manufacture example 1 into width 130mm * depth 230mm * height 6mm.

  About the manufactured vacuum heat insulating materials 1-4, thermal conductivity (mW / m * K) was measured using HFM436 (NETZSCH company_made, heat flow meter part center 100mmx100mm).

  The results are shown in Table 3 below.

  As shown in Table 3 above, it is clear that the influence of the heat bridge can be suppressed by using the electrolytic nickel foil of the present invention as compared with the conventional rolled aluminum foil.

1 ... Vacuum insulation
2 ... exterior materials,
3, 5 ... plastic film,
4 ... Electrolytic metal foil,
6 ... Core material,
7: Gas adsorbent,
8: Joining part (seal part).

Claims (5)

  A vacuum heat insulating material that encloses a core material and a gas adsorbent so as to be sandwiched between a pair of outer packaging materials having gas barrier properties, and is sealed by reducing the pressure inside the outer packaging material. A vacuum heat insulating material comprising at least one of a laminate of electrolytic metal foil and plastic.   The vacuum heat insulating material according to claim 1, wherein the electrolytic metal foil has a thermal resistance (R) of 650 K / W or more.   The vacuum heat insulating material of Claim 1 or 2 whose thickness of the said electrolytic metal foil is 1-10 micrometers.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein the electrolytic metal foil is a nickel foil or an alloy foil containing nickel.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein the electrolytic metal foil is an alloy foil containing copper.