JP6711202B2 - Skin material for vacuum insulation material, bag body for vacuum insulation material, and vacuum insulation material - Google Patents

Description

The present invention relates to a skin material for a vacuum heat insulating material, a bag body for a vacuum heat insulating material, and a vacuum heat insulating material.

In houses, buildings, vehicles, heat and cold storage containers, refrigerators, water heaters, etc., vacuum heat insulating materials are used to reduce energy consumption by heat insulation. As the vacuum heat insulating material, for example, a material in which a core material made of powder or fibers is sealed under reduced pressure in an outer bag is known.
The outer bag is manufactured by heat-sealing an outer skin material made of a gas barrier film. Therefore, the outer skin material is required to have a gas barrier property and a heat fusion property that enables heat sealing.

Conventionally, in order to provide a heat-welding property to a jacket material of a vacuum heat insulating material, a heat-sealing layer is formed of a resin film having a low heat resistance such as polyethylene or polypropylene having a relatively low melting point. However, when it is attempted to apply the heat insulation to a high temperature portion exceeding 100° C., it is very difficult to maintain the heat insulation property for a long period of time because the heat resistance of the heat welding layer is low.
Therefore, as a film having a gas barrier property and a heat fusion property applicable in a high temperature region, Patent Document 1 discloses a laminated film including an aluminum foil as a gas barrier layer, and the heat fusion layer made of polychlorotrifluoroethylene. It is described that it is used as a skin material for a vacuum heat insulating material.

JP, 2005-24038, A

However, as a result of studies by the inventors of the present application, it was found that the laminated film of Patent Document 1 is easily peeled off from the gas barrier layer and the heat fusion layer when used at a low temperature.
In view of the above circumstances, the present invention provides a vacuum heat insulating material skin material that is unlikely to separate the gas barrier layer and the heat-sealing layer even when used at low temperatures, and a vacuum heat insulating material bag body and a vacuum heat insulating material using the skin material. The challenge is to provide.

The present invention has the following aspects.
[1] A heat-sealing layer containing a fluororesin having the following adhesive functional group and having a melting point of 160 to 240° C.,
A metal gas barrier layer,
Has a resin protective layer,
The heat fusion layer, the gas barrier layer and the protective layer are laminated in this order,
The heat insulation layer and the gas barrier layer are in direct contact with each other.
Adhesive functional group: carboxy group, acid anhydride group, carboxylic acid halide group, epoxy group, hydroxy group, amino group, thiol group, carbonate bond, amide bond, urethane bond, urea bond, ester bond and ether bond At least one functional group selected from.
[2] The outer cover material for a vacuum heat insulating material according to [1], wherein the fluororesin of the heat fusion layer is a copolymer having a unit derived from ethylene and a unit derived from tetrafluoroethylene.
[3] The skin material for vacuum heat insulating material according to [1] or [2], wherein the gas barrier layer is an aluminum layer.
[4] The outer cover material for a vacuum heat insulating material according to any one of [1] to [3], wherein the protective layer contains a fluororesin.
[5] The outer cover material for a vacuum heat insulating material according to [4], wherein the protective layer contains a fluororesin having the following adhesive functional group, and the gas barrier layer and the protective layer are in direct contact with each other.
Adhesive functional group: carboxy group, acid anhydride group, carboxylic acid halide group, epoxy group, hydroxy group, amino group, thiol group, carbonate bond, amide bond, urethane bond, urea bond, ester bond and ether bond At least one functional group selected from.
[6] The outer cover material for a vacuum heat insulating material according to [4] or [5], wherein the fluororesin of the protective layer is a copolymer having a unit derived from ethylene and a unit derived from tetrafluoroethylene.
[7] The outer cover material for a vacuum heat insulating material according to any one of [1] to [6], wherein an arbitrary layer is further laminated on the side of the protective layer opposite to the gas barrier layer.
[8] A vacuum characterized in that the heat-sealing layers are heat-sealed at the periphery of the outer skin material for vacuum heat insulating material according to any one of [1] to [7]. Bag for heat insulating material.
[9] A vacuum heat insulating material comprising the vacuum heat insulating material bag body according to [8] and a core material that is vacuum-encapsulated in the bag body.
[10] The vacuum heat insulating material according to [9], wherein the core material contains powdery silica.

According to the outer cover material for a vacuum heat insulating material and the bag body for a vacuum heat insulating material of the present invention, it is possible to obtain a vacuum heat insulating material in which the gas barrier layer and the heat-sealing layer are not easily separated even when used at low temperatures. In the vacuum heat insulating material of the present invention, the gas barrier layer and the heat-sealing layer are not easily peeled off even when used at a low temperature, and a high vacuum state can be maintained.

It is sectional drawing which shows an example of the outer skin material for vacuum heat insulating materials of this invention. It is a figure which shows the result of the low temperature tensile test of the skin material for vacuum heat insulating materials which concerns on an Example. It is a figure which shows the result of the low temperature tensile test of the skin material for vacuum heat insulating materials which concerns on a comparative example.

The following definitions of terms apply throughout the specification and claims.
"Melting point" means the temperature corresponding to the melting peak measured by the differential scanning calorimetry (DSC) method. In addition, when several melting peaks are obtained, it means the temperature which shows the endothermic main peak in the DSC curve measured by the differential scanning calorimetry (DSC) method.
The "fluororesin" means a polymer compound having a fluorine atom in the molecule.
The “gas barrier layer” means a layer having a property of being less permeable to gases such as water vapor and oxygen than the materials contained in the heat fusion layer, the protective layer, and any layer provided as necessary.
The “unit” means a portion derived from a monomer that is present in the polymer to constitute the polymer. Further, a unit is a unit in which the structure of a unit is chemically converted after the formation of a polymer.
In some cases, a unit derived from an individual monomer is referred to by a name obtained by adding “unit” to the name of the monomer.

[Skin material for vacuum insulation]
The outer cover material for a vacuum heat insulating material of the present invention has a heat-sealing layer containing a fluororesin, a gas barrier layer made of metal, and a protective layer made of resin.
The heat fusion layer, the gas barrier layer, and the protective layer are laminated in this order, and the heat fusion layer and the gas barrier layer are in direct contact with each other.
For the purpose of further improving strength, another layer (arbitrary layer) may be further laminated on the surface of the protective layer opposite to the gas barrier layer. Further, any other layer may be interposed between the gas barrier layer and the protective layer. An optional layer interposed between these layers includes an adhesion promoting layer.
The jacket material for a vacuum heat insulating material according to the present invention is used as a bag body for vacuum-sealing a core material by sealing one or more sheets with their heat-sealing layers facing each other and sealing the peripheral edges by heat-sealing. ..

FIG. 1 is a cross-sectional view showing an example of an outer skin material for a vacuum heat insulating material of the present invention. The skin material 10 for vacuum heat insulating material includes a heat-sealing layer 12, a gas barrier layer 14 adjacent to the heat-sealing layer 12, a protective layer 16 adjacent to the gas barrier layer 14, and an optional layer 18 adjacent to the protective layer 16. Consists of.

(Heat fusion layer)
The heat-sealing layer is a resin layer having heat sealability between the heat-sealing layers.
The heat fusion layer contains a fluororesin and has a melting point of 160 to 240°C.

<Melting point>
The melting point of the heat-sealing layer is 160 to 240°C, particularly preferably 180 to 240°C. When the melting point of the heat-sealing layer is equal to or lower than the upper limit of the above range, the heat-sealing layers can be heat-sealed and laminated with the adjacent layer at a relatively low temperature. If the skin material for a vacuum heat insulating material can be manufactured at a relatively low temperature, deformation is suppressed, and wrinkles and breakage of the skin material for a vacuum heat insulating material are suppressed.
The melting point of the heat-sealing layer mainly depends on the melting points of the resin components forming the heat-sealing layer.

<Fluorine resin>
The heat fusion layer contains a fluororesin. The melting point of the fluororesin of the heat-sealing layer is preferably 160 to 240°C, and particularly preferably 180 to 240°C. When the melting point of the fluororesin is within the above range, the melting point of the heat fusion layer is likely to be within the above predetermined range. In addition, when a fluororesin is included, brittle fracture at low temperatures is easily suppressed.

The fluororesin of the heat-sealing layer has an adhesive functional group. When the fluororesin of the heat-sealing layer has an adhesive functional group, the heat-sealing layer can easily exhibit the heat-sealing property. Further, since the heat sealability is easily exhibited, the adhesiveness with the gas barrier layer is also excellent.
The adhesive functional group may be derived from a monomer having an adhesive functional group, may be derived from a polymerization initiator or a chain transfer agent, and is a compound graft-polymerized to a fluororesin. May be derived from.

Examples of the adhesive functional group include carboxy group, acid anhydride group, carboxylic acid halide group, epoxy group, hydroxy group, amino group, thiol group, carbonate group, amide group, urethane bond, urea bond, ester group and ether group. At least one selected from the group consisting of A carboxy group or an acid anhydride group is particularly preferable in terms of excellent heat-sealing property of the heat-sealing layer.

The fluororesin of the heat-sealing layer is an ethylene unit and a tetrafluoroethylene (hereinafter, also referred to as “TFE”) unit from the viewpoint of excellent heat-sealing property of the heat-sealing layer and excellent moldability into a film or the like. A copolymer having a unit having an adhesive functional group (hereinafter, a copolymer having an ethylene unit and a TFE unit is referred to as "ETFE", a copolymer having an ethylene unit, a TFE unit and a unit having an adhesive functional group). The polymer is also referred to as “adhesive ETFE”.), a copolymer having a TFE unit, a perfluoro(alkyl vinyl ether) unit, and a unit having an adhesive functional group, and a vinylidene fluoride unit (hereinafter, also referred to as “VDF”). And at least one selected from the group consisting of a copolymer having a unit having an adhesive functional group and a copolymer having a vinyl fluoride unit and a unit having an adhesive functional group. Adhesive ETFE is particularly preferable because it is easy to adjust the melting point of the fluororesin to the above range.

The adhesive ETFE may have a unit derived from a monomer other than ethylene, TFE and a monomer having an adhesive functional group, if necessary.
Examples of the monomer having an adhesive functional group include itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, and maleic anhydride.
Other monomers include fluoroolefins (excluding tetrafluoroethylene).
), fluoro (alkyl vinyl ether), and the like.

Specific examples of the adhesive ETFE include "fluorine resin having a functional group" described in International Publication No. 2006/134476, "adhesive functional group-containing fluororesin" described in JP 2012-106494 A, international publication. The "fluorine-containing ethylenic polymer having a carbonyl group" described in No. 2001/058686 and the like can be mentioned.

<Method for producing fluororesin>
The fluororesin of the heat-sealing layer can be produced by polymerizing in a polymerization medium in the presence of a polymerization initiator, if necessary using a chain transfer agent.

As the polymerization medium, perfluorocarbons such as n-perfluorohexane, n-perfluoroheptane, perfluorocyclobutane, perfluorocyclohexane and perfluorobenzene, 1,1,2,2-tetrafluorocyclobutane, CF ₃ CFHCF ₂ CF ₂ CF ₃ , CF ₃ (CF ₂ ) ₄ H, CF ₃ CF ₂ CFHCF ₂ CF ₃ , CF ₃ CFHCFHCF ₂ CF ₃ , CF ₂ HCFHCF ₂ CF ₂ CF ₃ , CF ₃ (CF ₂ ) ₅ H, CF ₃ CH(CF ₃ )CF ₂ CF ₂ CF ₃ , CF ₃ CF(CF ₃ )CFHCF ₂ CF ₃ , CF ₃ CF(CF ₃ )CFHCFHCF ₃ , CF ₃ CH(CF ₃ )CFHCF ₂ CF ₃ , CF ₃ CF ₂ Hydrofluorocarbons such as CH ₂ CH ₃ , CF ₃ (CF ₂ ) ₃ CH ₂ CH ₃ , CF ₃ CH ₂ OCF ₂ CF ₂ H, CF ₃ (CF ₃ )CFCF ₂ OCH ₃ , CF ₃ (CF ₂ ) ₃ Hydrofluoroethers such as OCH ₃ are preferable, CF ₃ (CF ₂ ) ₅ H and CF ₃ CH ₂ OCF ₂ CF ₂ H are more preferable, and CF ₃ (CF ₂ ) ₅ H is most preferable.

As the chain transfer agent, methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, 2, Alcohols such as 2,3,3,3-pentafluoropropanol, hydrocarbons such as n-pentane, n-hexane and cyclohexane, hydrofluorocarbons such as CF ₂ H ₂ , ketones such as acetone, methyl mercaptan, etc. Preferred are mercaptans, esters such as methyl acetate and ethyl acetate, and ethers such as diethyl ether and methyl ethyl ether.

Of these, methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, 2,2,2. Alcohols such as 3,3,3-pentafluoropropanol are more preferred, and methanol is most preferred.
The amount of the chain transfer agent used is preferably 0.01 to 50% by mass, more preferably 0.02 to 40% by mass, most preferably 0.05 to 20% by mass, based on the total weight of the polymerization medium and the chain transfer agent. preferable.

As the polymerization initiator, a radical polymerization initiator having a half-life of 10 hours (also referred to as a 10-hour half-life temperature) of 0 to 100° C. is preferable, and a radical not containing a chlorine atom of 20 to 90° C. A polymerization initiator is more preferable, and a radical polymerization initiator having a temperature of 20 to 60° C. is particularly preferable. Specific examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile, peroxydicarbonates such as diisopropylperoxydicarbonate, tert-butylperoxypivalate, tert-butylperoxyisobutyrate, tert-butylperoxyacetate. A non-fluorinated diacyl peroxide such as a peroxy ester, isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, lauroyl peroxide, etc., (Z(CF ₂ ) _p COO) ₂ (where Z is a hydrogen atom or a fluorine atom) , P is an integer of 1 to 10) and the like, fluorine-containing diacyl peroxides, perfluoro tert-butyl peroxide, inorganic peroxides such as potassium persulfate, sodium persulfate and ammonium persulfate.

<Other ingredients>
The heat-sealing layer may contain a fluororesin having no adhesive functional group or a component other than the fluororesin within a range not impairing the effects of the present invention. As components other than the fluororesin, polyamide, amino group-containing polymer, fluoroelastomer (fluororubber having VDF unit, fluororubber having propylene unit and TFE unit, etc.) and its cross-linked product, resin particles (polytetrafluoroethylene Particles, particles of polyether ether ketone, particles of polyphenylene sulfide, etc.) and the like.

The proportion of the fluororesin having an adhesive functional group in the heat-sealing layer is preferably 5 to 100% by mass, and preferably 20 to 100% by mass in the heat-sealing layer (100% by mass). More preferably, 50 to 100 mass% is particularly preferable.
The proportion of the adhesive ETFE in the fluororesin of the heat fusion layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass. When the ratio is within the above range, a heat-welding layer having excellent heat-sealing strength can be obtained. The melting point of the fluororesin of the heat-sealing layer is preferably 160 to 240°C.

<Thickness of heat fusion layer>
The thickness of the heat fusion layer is preferably 1 to 200 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 60 μm. When the thickness of the heat fusion layer is at least the lower limit value of the above range, the heat seal strength is excellent. When the thickness of the heat fusion layer is not more than the upper limit value of the above range, the outer cover material for vacuum heat insulating material is excellent in flexibility.

(Gas barrier layer)
The gas barrier layer is a layer made of a metal material that suppresses invasion of gas such as water vapor and oxygen from the outside to the inside of the bag. The metal forming the gas barrier layer may be a metal foil or a vapor deposition film deposited on a protective layer described later.
When the protective layer described later contains a fluororesin having an adhesive functional group and is laminated so that the gas barrier layer and the protective layer are in direct contact with each other, the gas barrier layer is not a vapor deposition film but a metal foil.
When the metal forming the gas barrier layer is a vapor deposition film vapor-deposited on the protective layer described later, the vapor deposition film is laminated so as to be in direct contact with the heat fusion layer.

The metal material forming the gas barrier layer may be appropriately selected from known gas barrier metal materials.
As the metal material having a gas barrier property, at least one selected from the group consisting of aluminum and stainless steel is preferable from the viewpoints of excellent gas barrier properties, metal foil moldability, and ease of vapor deposition on a protective layer described later. Aluminum is particularly preferred. The aluminum may be high-purity aluminum or an aluminum alloy.

In the case of a metal foil, the thickness of the gas barrier layer is preferably 6 to 50 μm, particularly preferably 6 to 30 μm. When the thickness of the gas barrier layer is at least the lower limit value of the above range, pinholes can be suppressed from being generated, and gas can be sufficiently suppressed from entering the bag body from the outside to the inside. When the thickness of the gas barrier layer is not more than the upper limit value of the above range, heat bridge of the vacuum heat insulating material can be suppressed.
When the gas barrier layer is a vapor deposition film, it is preferably 0.001 to 0.5 μm, and particularly preferably 0.005 to 0.2 μm. When there are a plurality of gas barrier layers, which are vapor-deposited films, the total thickness may be within the above range. Further, the gas barrier layer may be a combination of a metal foil and a vapor deposition film. In the above case, the total thickness of the gas barrier layers is preferably 6 to 50 μm.

(Protective layer)
The protective layer is a layer that protects the gas barrier layer. When an arbitrary layer is provided on the side of the protective layer opposite to the gas barrier layer as shown in FIG. 1, it can also serve as an adhesive layer for adhering the gas barrier layer and the arbitrary layer. When the protective layer contains a resin having an adhesive functional group, the protective layer more easily functions as an adhesive layer.
The protective layer is preferably composed of a thermoplastic resin. Examples of the thermoplastic resin used for the protective layer include fluororesin, polyamide resin, polyolefin resin, polyester resin and the like.

160 degreeC or more is preferable, as for the melting|fusing point of the thermoplastic resin which comprises a protective layer, 160-240 degreeC is more preferable, 180-240 degreeC is especially preferable. When the melting point of the thermoplastic resin forming the protective layer is equal to or higher than the lower limit of the above range, manufacturing defects such as fusion with a roll during thermal lamination can be suppressed. If the melting point of the thermoplastic resin forming the protective layer is not more than the upper limit value of the above range, it can be laminated with the adjacent layer at a relatively low temperature. If the skin material for a vacuum heat insulating material can be manufactured at a relatively low temperature, deformation is suppressed, and wrinkles and breakage of the skin material for a vacuum heat insulating material are suppressed.

The protective layer preferably contains a fluororesin. The melting point of the fluororesin contained in the protective layer is preferably 160 to 280°C, particularly preferably 180 to 240°C. When the melting point of the fluororesin is within the above range, the melting point of the protective layer is likely to fall within the above predetermined range. When the protective layer contains a fluororesin, brittle fracture at low temperature is easily suppressed.

Examples of the fluororesin contained in the protective layer include the same as the fluororesin of the heat fusion layer described above, and the preferred embodiments are also the same. Further, the preferable manufacturing conditions are also the same.
The fluororesin contained in the protective layer may be of the same type as the fluororesin of the heat-sealing layer or of a different type. The fluororesin contained in the protective layer is preferably the same type as the fluororesin of the heat-sealing layer from the viewpoint of easy production of the outer covering material for vacuum heat insulating material.

The protective layer containing a fluororesin may contain a fluororesin having no adhesive functional group or a component other than the fluororesin. Examples of the components other than the fluororesin include those similar to the other components contained in the heat-sealing layer.

The proportion of the fluororesin in the protective layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass in the protective layer (100% by mass). preferable.
The proportion of the fluororesin having an adhesive functional group in the fluororesin of the protective layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass. ..
The proportion of ETFE in the fluororesin of the protective layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass.
The proportion of the adhesive ETFE in the fluororesin of the protective layer is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass.

The thickness of the protective layer is preferably 1 to 100 μm, more preferably 5 to 60 μm, particularly preferably 10 to 50 μm. When the thickness of the protective layer is at least the lower limit value of the above range, it is easy to protect the gas barrier layer from external force. Further, as shown in FIG. 1, when there is an arbitrary layer and it plays a role of an adhesive layer for adhering between the gas barrier layer and the arbitrary layer, the adhesive strength is excellent. When the thickness of the protective layer is equal to or less than the upper limit value of the above range, the outer cover material for vacuum heat insulating material is excellent in flexibility.

When the protective layer is a support layer for the gas barrier layer made of a vapor deposition film, the protective layer functioning as the support layer for the gas barrier layer is a resin film. As the resin film, for example, a polyethylene terephthalate film, an ethylene-vinyl alcohol copolymer film, or the above-mentioned fluororesin film can be used. When functioning as a support layer, the thickness of the protective layer is preferably 1 to 200 μm, particularly preferably 10 to 100 μm.

(Adhesion promoting layer)
An adhesion promoting layer may be provided in order to improve the adhesive force between the gas barrier layer and the protective layer and the adhesive force between the protective layer and any layer. By having the adhesion promoting layer, the heat-sealing property is improved, and the fusion can be easily performed even at a low temperature to enable the sealing, so that the productivity can be improved.

The method for forming the adhesion promoting layer is not particularly limited, and examples thereof include the following methods.
A method in which a coating agent containing a resin having an affinity for the protective layer or a resin having a functional group capable of reacting with the adhesive functional group in the protective layer is applied to the surface of the gas barrier layer and dried.
-A method of subjecting the surface of the gas barrier layer to a chemical treatment such as boehmite treatment.
A method of applying a silane coupling agent on the surface of the gas barrier layer.
-A method of applying electromagnetic energy or the like to the surface of the gas barrier layer in the presence of a reactive gas.

As a method for forming the adhesion promoting layer, a method of applying a chemical treatment or a method of applying a silane coupling agent to the surface of the gas barrier layer, which has excellent compatibility with the protective layer and can shorten the time required for heat fusion. Is preferred.

The silane coupling agent is preferably a compound having a hydrolyzable silyl group and a group capable of forming a bond with the fluororesin in the heat-sealing layer or the protective layer by a chemical reaction, hydrogen bond or the like. As the hydrolyzable silyl group, an alkoxysilyl group is preferable, and methoxysilane and ethoxysilane are particularly preferable from the viewpoint of high hydrolysis rate.
As the group capable of forming a bond with a fluororesin by a chemical reaction or a hydrogen bond, an amino group, an epoxy group, a methacryl group and a mercapto group are preferable, and an amino group and an epoxy group are particularly preferable from the viewpoint of excellent reactivity with the fluororesin. preferable.

When the silane coupling agent is applied, it is preferable to use a solution dissolved in water, an alcohol solvent (ethanol, isopropyl alcohol, etc.), or a mixed solvent of water and an alcohol solvent. The content of the silane coupling agent in the solution is preferably 0.1 to 15% by mass, and particularly preferably 0.1 to 3% by mass, though it depends on the coating method and the post-treatment method described later. When it is at least the lower limit value of the above range, the adhesive strength to the heat fusion layer or the protective layer can be improved, and when it is at most the upper limit value of the above range, the silane coupling agent can be dissolved.

As a method of applying the silane coupling agent to the surface of the gas barrier layer, a commonly used coating method such as spray coating or dip coating can be appropriately used.
When the silane coupling agent is applied as the above solution, the solvent is dried and solidified at the same time after the application. It may be washed with water before drying to wash away an excess amount of the silane coupling agent (Japanese Patent Laid-Open No. 2009-19266).
The coating amount of the silane coupling agent is preferably 0.001 to 0.02 mg/cm ² from the viewpoint of improving the adhesive force with the heat fusion layer or the protective layer.

(Any layer)
The optional layer is a layer provided for the purpose of protecting the gas barrier layer together with the protective layer. By having the optional layer, the mechanical strength of the outer cover material for a vacuum heat insulating material is increased.
The optional layer may be a single layer or multiple layers. When the arbitrary layer is a single layer, it is preferably a layer containing one or both of polyamide and polyamideimide (hereinafter referred to as “polyamide etc.”) (hereinafter referred to as “polyamide etc.-containing layer”). When the arbitrary layer is a multi-layer, the layer in contact with the protective layer is preferably a polyamide-containing layer.

Examples of polyamides include nylon 6, nylon 66, nylon 11, nylon 12, special nylon, and mixtures thereof.
Examples of the polyamide-imide include compounds represented by the following formula (1). In Formula (1), Ar is an arylene group and n is the number of repetitions. Ar in formula (1) is preferably formula (2).

The proportion of the polyamide or the like in the polyamide-containing layer is preferably 20 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 70 to 100% by mass in the polyamide-containing layer (100% by mass). When the proportion of the polyamide or the like in the polyamide-containing layer is at least the lower limit value of the above range, the mechanical strength of the outer cover material for a vacuum heat insulating material is sufficiently excellent.

The polyamide-containing layer may contain other components as long as the effects of the present invention are not impaired.
Other components include known resin additives, resins other than polyamide, etc., such as polyester (polyethylene terephthalate, etc.), polyolefin (ethylene resin, propylene resin, etc.), acrylic resin, linear resin, etc. Thermoplastic polyurethane etc.) and the like.
The proportion of other components in the polyamide-containing layer is preferably 0 to 80% by mass, more preferably 0 to 50% by mass, and particularly preferably 0 to 30% by mass in the polyamide-containing layer (100% by mass). .. When the ratio of the other components in the polyamide-containing layer is not more than the upper limit value of the above range, the mechanical strength of the vacuum heat insulating material skin material is sufficiently excellent.

When any layer is a multilayer and has another layer on the side opposite to the protective layer of the polyamide-containing layer, the melting point is 160 to 240° C. between the other layer and the polyamide-containing layer, In addition, a layer containing a fluororesin having an adhesive functional group may be arranged.

The thickness of the optional layer is preferably 10 to 100 μm, particularly preferably 25 to 100 μm.
When the thickness of any layer is not less than the lower limit value of the above range, the outer cover material for vacuum heat insulating material has sufficiently excellent mechanical strength.
When the thickness of any layer is not more than the upper limit value of the above range, the outer cover material for vacuum heat insulating material is excellent in flexibility.

(Manufacturing method of skin material for vacuum insulation material)
As the method for producing the outer cover material for vacuum heat insulating material of the present invention, a method of hot pressing each layer formed into a film shape (thermal lamination method); a method of melt extruding the material of each layer using a multilayer die (coextrusion method) ); a method (extrusion laminating method) of melt-extruding the material of another layer on the layer formed into a film. Two or more of these methods may be combined.
Specific examples of the method for manufacturing the outer cover material for a vacuum heat insulating material of the present invention include the following methods.

<Method (I)>
A fluororesin film to be a heat-sealing layer and a metal foil (gas barrier layer) are extrusion-laminated to obtain a skin material (1) composed of the heat-sealing layer and the gas barrier layer.
-The outer skin material (1) and the fluororesin which becomes the protective layer are heat laminated so that the gas barrier layer and the protective layer are in contact with each other to obtain the outer skin material for a vacuum heat insulating material of the present invention.

<Method (II)>
-The fluororesin film serving as the heat-sealing layer and the metal foil (gas barrier layer) are heat-laminated to obtain the outer cover material (1) including the heat-sealing layer and the gas barrier layer.
-The fluororesin film and polyamide film used as a protective layer are heat-laminated, and the outer skin material (2) which consists of a protective layer and arbitrary layers is obtained.
-The outer skin material (1) and the outer skin material (2) are heat laminated so that the gas barrier layer and the protective layer are in contact with each other to obtain the outer skin material for a vacuum heat insulating material of the present invention.

<Method (III)>
A fluororesin which will be a heat-sealing layer is extrusion-laminated on the gas barrier layer to obtain an outer skin material (1) including the heat-sealing layer and the gas barrier layer.
-The fluororesin film and polyamide film used as a protective layer are heat-laminated, and the outer skin material (2) which consists of a protective layer and arbitrary layers is obtained.
-The outer skin material (1) and the outer skin material (2) are heat laminated so that the gas barrier layer and the protective layer are in contact with each other to obtain the outer skin material for a vacuum heat insulating material of the present invention.

<Method (IV)>
A fluororesin which will be a heat-sealing layer is extrusion-laminated on the gas barrier layer to obtain an outer skin material (1) including the heat-sealing layer and the gas barrier layer.
-A fluororesin to be a protective layer and polyamide are co-extruded to obtain a skin material (2) comprising a protective layer and an arbitrary layer.
-The outer skin material (1) and the outer skin material (2) are heat laminated so that the gas barrier layer and the protective layer are in contact with each other to obtain the outer skin material for a vacuum heat insulating material of the present invention.

<Method (V)>
-The fluororesin which becomes a heat-sealing layer is heat-laminated on the gas barrier layer to obtain the outer skin material (1) including the heat-sealing layer and the gas barrier layer.
-A fluororesin to be a protective layer and polyamide are co-extruded to obtain a skin material (2) comprising a protective layer and an arbitrary layer.
-The outer skin material (1) and the outer skin material (2) are heat laminated so that the gas barrier layer and the protective layer are in contact with each other to obtain the outer skin material for a vacuum heat insulating material of the present invention.

(Mechanism of action)
The present inventors examined the cause of the gas barrier layer and the heat-sealing layer being easily peeled off when the laminated film of Patent Document 1 is used at a low temperature. As a result, it has been found that the adhesive agent that bonds the gas barrier layer and the heat-sealing layer causes brittle fracture at low temperature. In the laminated film of Patent Document 1, it is essential to use an adhesive in order to laminate the aluminum foil and the resin layer.
In the present invention, by using a resin having an adhesive functional group for the heat-sealing layer, the heat-sealing layer and the gas barrier layer can be directly laminated without using an adhesive. Therefore, it is possible to avoid a situation in which the adhesive is brittlely broken at a low temperature.
Further, in the present invention, a fluororesin is used for the heat fusion layer. Fluororesin has better elongation characteristics at low temperatures than other resins, and is less prone to brittle fracture at low temperatures.
Therefore, the skin material of the present invention does not easily break brittlely even when used at low temperatures, and the gas barrier layer and the heat-sealing layer are also unlikely to peel off.
Furthermore, if a resin having an adhesive functional group, especially a fluororesin, is also used for the protective layer and the protective layer and the gas barrier layer are directly laminated without using an adhesive, the situation of brittle fracture at low temperature is further avoided. It is easy to do and the low temperature characteristics are improved.

[Vacuum insulation bag]
The bag for vacuum heat insulating material of the present invention is formed by heat sealing the heat-sealing layers to each other at the periphery of one or more outer skin materials for vacuum heat insulating material of the present invention. The heat fusion layer is arranged on the innermost side (the side in contact with the core material).

The bag for vacuum heat insulating material of the present invention is a three-side sealed bag in which one outer skin material for vacuum heat insulating material is folded back and overlapped in the middle, and the heat-sealing layers at the peripheral edges of the three sides are heat-sealed. Body: A four-side sealed bag body in which two sheets of vacuum insulation material are superposed and the heat-sealing layers at the peripheral edges of the four sides are heat-sealed.

[Vacuum insulation material]
The vacuum heat insulating material of the present invention comprises a core material vacuum-enclosed in the vacuum heat insulating material bag of the present invention.
The shape of the vacuum heat insulating material is not particularly limited and can be appropriately determined according to the shape of the construction surface of the heat insulating object. Usually, the shape of the vacuum heat insulating material is plate-like, and may be flat or curved with respect to the construction surface.
The degree of vacuum inside bags vacuum insulation material in the vacuum heat insulating material has excellent thermal insulation performance can be obtained and from the point of the life of the vacuum heat insulating material is increased, 1 × is preferably from ^{10 3 Pa, 1 × 10 2} Pa or less Is more preferable.

(Core material)
As the core material, a known core material used for a vacuum heat insulating material can be used. Examples thereof include, but are not limited to, a sheet-shaped heat insulating material containing powder, glass wool, and an airgel blanket. In the case of a core material containing powder, it is preferable that the heat insulating material contains fibers in addition to the powder from the viewpoint of easily obtaining a high-strength core material. In the case of a core material containing powder, the heat insulating material may contain a binder.

<Powder>
The case of a core material containing powder will be described below as an example.
As the powder, a known powder usually used for core materials can be used. Specific examples thereof include fumed silica, porous silica, radiation suppressing material and the like. It is preferable that the powder contains fumed silica because a core material having sufficient strength can be easily obtained.
The powder may be used alone or in combination of two or more.

Since fumed silica is an extremely fine powder, its specific surface area is usually used as an index for indicating the size of particles.
The specific surface area of the fumed silica is preferably 50 to 400 m ² / g, more preferably ^{100~350m 2 / g, 200~300m 2 /} g is particularly preferred. When the specific surface area of fumed silica is equal to or more than the lower limit value of the above range, excellent heat insulating performance is likely to be obtained. If the specific surface area of the fumed silica is equal to or less than the upper limit value of the above range, the fumed silica can be easily handled. The specific surface area is measured by a nitrogen adsorption method (BET method).

When used in combination porous silica, the specific surface area of porous silica is preferably 100~800m ² / g, more preferably ^{200~750m 2 / g, 300~700m 2 /} g is particularly preferred. When the specific surface area of the porous silica is equal to or more than the lower limit value of the above range, excellent heat insulating performance is easily obtained. When the specific surface area of the porous silica is not more than the upper limit value of the above range, it is easily industrially available and the strength of the porous silica is excellent.

The average particle diameter of the porous silica is preferably 1 to 300 μm, more preferably 2 to 150 μm, particularly preferably 3 to 100 μm, when measured on a volume basis by a laser diffraction scattering method, a Coulter counter method, or the like. When the average particle size of the porous silica is at least the lower limit value of the above range, porous silica having a high porosity can be easily obtained, and excellent heat insulating performance can be easily obtained. When the average particle size of the porous silica is not more than the upper limit value of the above range, the density of the core material does not become too high, and excellent heat insulating performance is easily obtained.

Examples of the radiation suppressing material include metal particles (aluminum particles, silver particles, gold particles, etc.), inorganic particles (graphite, carbon black, silicon carbide, titanium oxide, tin oxide, iron oxide, potassium titanate, etc.) and the like. Be done.

<Binder>
From the point that sufficient strength is easily obtained even when the core material has a low density, a binder can be included in the heat insulating material in order to maintain the shape of the core material. The binder may be an organic binder or an inorganic binder. Among them, as the binder, an inorganic binder is preferable because it has low thermal conductivity and easily obtains excellent heat insulating performance.
Examples of the inorganic binder include sodium silicate, aluminum phosphate, magnesium sulfate, magnesium chloride and the like. Among them, sodium silicate is particularly preferable because excellent heat insulating performance is easily obtained.
The binder is preferably dissolved in a solvent and used as a binder liquid, and an aqueous solution is more preferable.

<fiber>
When the heat insulating material contains fibers, a high-strength core material can be easily obtained.
As the fibers, fibers usually used for vacuum heat insulating materials can be used, and examples thereof include resin fibers and inorganic fibers. Among these, inorganic fibers are preferable because they have less outgas under vacuum, are easy to suppress deterioration of heat insulation performance due to decrease of vacuum degree, and have excellent heat resistance. The fiber length of the fibers used is preferably 20 mm or less.

Examples of the inorganic fiber include alumina fiber, mullite fiber, silica fiber, glass wool, glass fiber, rock wool, slag wool, silicon carbide fiber, carbon fiber, silica alumina fiber, silica alumina magnesia fiber, silica alumina zirconia fiber, silica magnesia. Examples include calcia fibers.

<Preferred composition>
When powder is used as the core material, a preferable composition of the core material is a mass ratio of 50 to 90:0 to 20:5 to 15:5 to 30: fumed silica:porous silica:fiber:radiation suppressing material. Is preferred. When the binder is added, the proportion of the binder is preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of fumed silica.

(Vacuum insulation material manufacturing method)
The method for manufacturing the vacuum heat insulating material is not particularly limited, and includes, for example, a molding step of molding a heat insulating material to obtain a core material, and a depressurizing method for sealing the core material in a vacuum heat insulating material bag body under reduced pressure to obtain a vacuum heat insulating material. Encapsulation step is included.
As a method for molding the heat insulating material to obtain the core material, a known method can be adopted, and examples thereof include a method of charging the heat insulating material into a mold and pressurizing it.
In the reduced pressure sealing step, for example, the core material is housed in a vacuum heat insulating material bag left as an opening without heat-sealing one side, and the opening portion of the vacuum heat insulating material bag body is heat-sealed under a reduced pressure condition. After sealing, the outside of the vacuum heat insulating bag is returned to atmospheric pressure conditions to obtain a vacuum heat insulating material.

[Measurement method and evaluation method]
(Melting point (℃))
It was determined from the endothermic peak when each material was heated to 300° C. at 10° C./minute in an air atmosphere using a scanning differential thermal analyzer (DSC220CU manufactured by SII Nano Technologies).

(Low temperature tensile test)
The jacket material (laminate) obtained in each example was punched into a dumbbell-shaped No. 1 shape described in JIS K6215 to give a test piece, which was immersed in liquid nitrogen (-196° C.) at a speed of 3 mm/min. The stress change with tension and strain was measured. A universal material testing machine Technograph TGI 100kN manufactured by Minebea Co., Ltd. was used for the measurement.

〔material〕
(Fluorine resin)
According to the method described in Synthesis Example 1 of WO 2006/134764, TFE unit/ethylene unit/3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene unit/hexa A fluororesin A having a fluoropropylene unit/itaconic anhydride unit=44/48/0.8/8.0/0.2 (molar ratio) and a melting point of 190° C. was obtained.

(Example)
By the method (I), a skin material of Example 1 was obtained in which the fluororesin A having a thickness of 50 μm, the aluminum foil having a thickness of 12 μm, and the fluororesin A having a thickness of 50 μm were directly laminated in this order.

(Comparative example)
PET (polyethylene terephthalate) having a thickness of 12 μm, aluminum foil having a thickness of 9 μm, polyamide having a thickness of 25 μm, and linear low-density polyethylene having a thickness of 60 μm were laminated in this order with an adhesive, The skin material was obtained.
A urethane-based adhesive was used as the adhesive.
By the dry lamination method, a 12 μm-thick PET, a 9 μm-thick aluminum foil, a 25 μm-thick polyamide, and a 60 μm-thick linear low-density polyethylene were laminated in this order to obtain a skin material of Comparative Example 1.

2 and 3 show the results of the low temperature tensile test performed on the laminates of Example 1 and Comparative Example 1 (each N=2). In Comparative Example 1 (FIG. 3), the stress suddenly ruptured around 5% and the stress became zero, whereas in Example 1 (FIG. 2), the stress did not break even when the strain exceeded 5%, and gradually increased. The stress gradually decreased, and the strain exceeded 6% and completely fractured.
This indicates that the laminate of Example 1 has better elongation characteristics at low temperatures. It is considered that the laminate of Example 1 has excellent elongation properties at low temperatures because the fluororesin has excellent low-temperature elongation properties and the fluororesin A having an adhesive functional group is directly laminated on the aluminum foil. Be done.

DESCRIPTION OF SYMBOLS 10... Outer skin material for vacuum heat insulation material, 12... Thermal fusion bonding layer, 14... Gas barrier layer, 16... Protective layer,
18... Any layer

Claims (8)

A heat-sealing layer containing a fluororesin having the following adhesive functional group and having a melting point of 160 to 240° C.,
A metal gas barrier layer,
Has a resin protective layer,
The protective layer contains a fluororesin, the fluororesin contained in the protective layer is the same type as the fluororesin contained in the heat fusion layer,
The heat fusion layer, the gas barrier layer and the protective layer are laminated in this order,
Further, the outer cover material for a vacuum heat insulating material, wherein the heat fusion layer and the gas barrier layer are in direct contact with each other , and the gas barrier layer and the protective layer are in direct contact with each other .
Adhesive functional group: carboxy group, acid anhydride group, carboxylic acid halide group, epoxy group, hydroxy group, amino group, thiol group, carbonate bond, amide bond, urethane bond, urea bond, ester bond and ether bond At least one functional group selected from. The skin material for a vacuum heat insulating material according to claim 1, wherein the fluororesin of the heat fusion layer and the protective layer is a copolymer having a unit derived from ethylene and a unit derived from tetrafluoroethylene. The outer cover material for a vacuum heat insulating material according to claim 1 or 2, wherein the gas barrier layer is an aluminum layer. The proportion of the fluororesin in the heat-sealing layer is 20 to 100% by mass of the heat-sealing layer, and the proportion of the fluororesin in the protective layer is 20 to 100% by mass of the protective layer. The outer skin material for a vacuum heat insulating material according to any one of claims 1 to 3. Wherein the gas barrier layer opposite the vacuum heat insulating material for the outer covering layer according to any one of claim 1 to 4, any of the layers is further laminated in the protective layer. The vacuum heat insulating material bag body the heat-fusible layer between at the periphery of the vacuum heat insulating material for the outer skin material, characterized in that it is heat-sealed as claimed in any one of one or more of claims 1 to 5 .. A vacuum heat insulating material comprising: the vacuum heat insulating material bag body according to claim 6 ; and a core material that is vacuum-enclosed in the bag body. The vacuum heat insulating material according to claim 7 , wherein the core material contains powdery silica.

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