JP2008240924A - Vacuum heat insulation material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum heat insulation material capable of being used safely and properly and almost free from risk such as deterioration of heat insulation property, generation of gas, generation of toxic gas and fire even if continuously used in a certain temperature range from an ultra low temperature lower than -100°C or even -200°C to a high temperature of 200°C or higher in the vacuum heat insulation material wherein a core material is packaged by an outer jacket material composed of a laminated film and its inner part is decompressed and sealed. <P>SOLUTION: In the vacuum heat insulation material of this invention, the core material is packaged by the outer jacket material and the inner part is decompressed and sealed. The outer jacket material consists of a heat seal layer composed of a plastic film as an inner-most layer, a gas barrier layer composed of a metal foil and a metal deposition film and the like and the laminated film of at least two-layer-structure including a protection layer composed of a plastic film and the like as need. About the plastic film composed of a thermoplastic resin film at least used for the heat seal layer, gas generation when heated to 200°C is substantially zero and its melting point is 300°C. The core material is composed of a fibrous layer mainly consisting of inorganic fiber. About the vacuum insulation material, gas generation when heated to 200°C is substantially zero and a rise rate of heat conductivity after heated at 250°C for 24 hours (the rise rate of heat conductivity after heated at 250°C for 24 hours to a heat conductivity at a normal temperature) is equal to or lower than 10%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vacuum heat insulating material that can be used in a wide arbitrary temperature range from an ultra-low temperature of −100 ° C. or lower, further −200 ° C. or lower to a high temperature of 200 ° C. or higher.

  Conventionally, as a vacuum heat insulating material, a dry material such as a needling mat made of inorganic fibers, felt, wool or the like, or a core material formed by wet forming inorganic fibers such as a papermaking method, a thermoplastic plastic film such as polyester or polyethylene, In general, a metal foil or a metal vapor-deposited metal is wrapped and wrapped in a laminated film, the air inside is removed, and then melt-sealed and molded.

  The thermoplastic film has a function of facilitating flexibility and workability of sealing by heating, and a metal foil or the like has a gas barrier function of preventing external air from entering. In addition, the core material has a function of reducing the heat convection space and slowing the movement of heat in order to enhance the heat insulation, so that the diameter of the inorganic fiber is reduced to 1 μm or less, or the shot in the inorganic fiber (non-fiber) It is practiced to reduce the thermal conductivity by reducing the content ratio of the liquefied granular material) or by arranging inorganic fibers in a direction perpendicular to the heat transfer direction.

  Conventional vacuum insulation materials such as the above are heat-saving promotion insulation materials for household appliances and vending machines such as refrigerators and rice cookers, insulation materials for maintaining freshness such as medical and various cooler boxes, and recently, The application of cold weather clothing to heat insulating materials is conceivable, and it is responding to the demand for high-performance heat insulation by reducing the thickness.

  However, the temperature environment using these heat insulating materials is at most about −30 ° C. to 120 ° C., and there are no problems with conventional core materials and thermoplastic films, but computers, flat TVs, high-speed printers, Copiers and other devices have generated heat sources around 150 ° C, and further downsizing of the device has reduced the distance from other components, especially heat-sensitive integrated circuits, and it has become a source of heat discharge or insulation. Along with the need for treatment, the risk of ignition has increased, and it has become necessary to consider incombustibility or incombustibility regarding the material of the heat insulating material.

  In addition, considering the use of vacuum heat insulation material at 150 ° C or higher, portable computers equipped with direct methanol fuel cells (DMFC) have recently appeared in the generator, but more efficient reformed methanol fuel cells are mobile. There is a need in the industry.

  Since the reformer that obtains hydrogen from methanol operates at an internal temperature of 280 ° C., a vacuum heat insulating material with higher heat resistance is required. The industry has recently been reported to have developed 882 W / L in volumetric power density. This is because the radiation-insulated glass case is further vacuum-insulated to contain the vaporizer, reformer, and CO oxidizer, and the internal temperature is 280 ° C and the external temperature is 50 ° C. It is a thing. Since this heat insulating case is a very expensive part, if a vacuum heat insulating material up to 300 ° C. can be provided by another method, it may contribute to the expansion of the fuel cell market.

  In the middle and high temperature region of about 150 ° C., a vacuum heat insulating material having a coating film containing an infrared reflection component or a radiation conduction suppressing means on the high temperature side of the vacuum heat insulating material has been proposed. Patent Document 1 is characterized in that the coating film containing the infrared reflection component is a metal powder, an inorganic powder, or a metal oxide powder, and the core material is mainly silica powder, inorganic fiber, conductive powder. It is said.

  The laminated jacket material has a three-layer structure, which includes a heat-sealing layer (heat seal layer), a gas barrier layer, and a protective layer, each of which is a flame-retardant material. Specifically, the heat fusion layer is a fluorine film (polychlorotrifluoride ethylene) having a melting point of 200 ° C. or higher, and the gas barrier layer is a metal film deposited on a heat resistant film (polyethylene naphthalate, polyimide) from the heat fusion layer. Things are used. As the protective layer, a film having a heat resistance higher than that of the heat fusion layer (tetrafluoroethylene / perfluoroalkoxyethylene copolymer, tetrafluoroethylene, polyetherketone, polysulfone, polyetherimide, etc.) has been proposed.

  Patent Document 2 employs a metal foil (aluminum, nickel) or a metal vapor-deposited film (aluminum, nickel) as radiation conduction suppression means. The core material is preferably fine powdered dry fumed silica (Aerosil 300). The laminated jacket material has a three-layer structure, which is composed of a heat fusion layer, a gas barrier layer, and a protective layer, each of which is a flame retardant material. Specifically, the heat fusion layer is a polyphenylene sulfide (PPS) film or a fluorine film (polychlorotrifluoride ethylene) having a melting point of 200 ° C. or higher, and the gas barrier layer is a film (polyethylene naphthalate, A material obtained by vapor-depositing a metal on (polyimide) is used. As the protective layer, a film having a heat resistance higher than that of the heat fusion layer (tetrafluoroethylene / perfluoroalkoxyethylene copolymer, tetrafluoroethylene, polyetherketone, polysulfone, polyetherimide, etc.) has been proposed.

JP-A-2005-24038 JP 2005-214250 A

  Considering use at 150 ° C or higher as a vacuum heat insulating material, and 200 ° C or higher, PPS film having a melting point of 280 ° C and polychlorotrifluorinated ethylene film having a melting point of 210 ° C have insufficient heat resistance. In continuous use, the heat-sealed layer cannot be melted to maintain a vacuum, and a decrease in heat insulating properties is assumed. Moreover, there is a risk of causing a fire of nearby parts due to leakage of high-temperature heat.

  In consideration of gas generation due to thermal decomposition, the fluorine-based film has a risk of generating toxic hydrogen fluoride or carcinogenic tetrafluoroethylene during high-temperature decomposition. Further, there is a risk of generating gas such as xylene, toluene, phenol, dichlorobenzene, polyetherimide film, dichrome benzene, PEEK (polyether ether ketone) film such as toluene, cresol, NN dimethylacetamide, etc.

  If a gas component is generated during the use of the vacuum heat insulating material, the heat conductivity of the vacuum heat insulating material is lowered, so that it cannot be used continuously. Further, since the above gas components contain toxic or ignitable components, there is a risk of causing safety problems. Further, in the case of PPS, since S (sulfur) is contained inside the molecule, there is a problem that the generation of sulfides causes corrosion and wear of the mold and press machine during processing.

  In view of such a conventional problem, the present invention is a vacuum heat insulating material in which a core material is packed with a covering material made of a laminate film, and the inside is decompressed and sealed, and is −100 ° C. or lower, further −200 ° C. Even in continuous use in any temperature range from the following ultra-low temperature to a high temperature of 200 ° C. or higher, there is almost no risk of heat insulation deterioration, gas generation, and further harmful gas generation and ignition, and it can be used safely and satisfactorily. It aims at providing a vacuum heat insulating material.

  In order to achieve the above object, the vacuum heat insulating material of the present invention is a vacuum heat insulating material formed by packing a core material with an outer cover material and depressurizing and sealing the inside, as described in claim 1, wherein the outer cover material is , A heat seal layer made of a plastic film as the innermost layer, a gas barrier layer made of a metal foil, a metal vapor-deposited film, etc., and a laminate film having at least a two-layer structure including a protective layer made of a plastic film or the like, if necessary, The plastic film used at least for the heat seal layer is composed of a thermoplastic resin film having substantially no gas generation when heated at 200 ° C. and a melting point of 300 ° C. or more, and the core material is a fiber layer mainly composed of inorganic fibers. The vacuum heat insulating material has substantially no gas generation when heated at 200 ° C., and the rate of increase in thermal conductivity after heating at 250 ° C. for 24 hours (heat transfer at normal temperature). 250 ° C. for rate, rate of increase in thermal conductivity after 24h heating) to equal to or less than 10%.

  The vacuum heat insulating material according to claim 2 is characterized in that, in the vacuum heat insulating material according to claim 1, the material of the thermoplastic resin film is polyimide, polyamideimide or liquid crystal polymer.

  The vacuum heat insulating material according to claim 3 is the vacuum heat insulating material according to claim 2, wherein the material of the thermoplastic resin film is thermoplastic polyimide having a melting point of 350 ° C. or higher.

  According to the present invention, in a vacuum heat insulating material in which a core material is packed with a cover material made of a laminate film and the inside is decompressed and sealed, inorganic fibers are used as the material of the core material, and the material of the cover material is 200. By using a thermoplastic film having a heat resistance of at least ° C., a vacuum heat insulating material that can withstand continuous use at 200 ° C. or higher can be provided. Even in continuous use at 200 ° C. or higher, the jacket material does not melt to lower the degree of vacuum or generate gas, so that the initial heat insulation characteristics can be maintained over a long period of time. Furthermore, there is almost no danger of toxic gas generation or ignition, and it can be used safely and satisfactorily.

  Therefore, if the vacuum heat insulating material of the present invention is used, it becomes possible to install circuit components, wiring boards, etc. that have poor heat resistance close to the heat source, which can contribute to downsizing of equipment and devices, and also contribute to energy saving. can do.

  In addition, when a plastic film made of a thermoplastic polyimide having a melting point of 350 ° C. or higher is used as the material of the jacket material, the polyimide generates gas at such a level that 19 ppm of water is generated even when heated at 260 ° C. Since it is substantially zero and does not generate any harmful gas, and has a resistance to -269 ° C, the polyimide film is used as the plastic film used at least for the heat seal layer, and the laminate film is selected using a metal foil as the gas barrier layer. If the material is made up and the core material is made up of fiber layers made of inorganic fibers, all of the constituent materials of the vacuum heat insulating material can be made up of materials that do not deteriorate even in the ultra-low temperature region below -200 ° C. , Long-term in a wide range of temperatures from ultra-low temperature of -200 ° C or lower to high temperature of 200 ° C or higher Over to be able to provide a vacuum heat insulating material which can be used safely and satisfactorily, high industrial value.

  The vacuum heat insulating material of the present invention includes at least two layers including a heat seal layer made of a plastic film as an innermost layer, a gas barrier layer made of a metal foil, a metal vapor-deposited film, and the like, and a protective layer made of a plastic film or the like as necessary. It is composed of a jacket material composed of a laminated film having a structure and a core material composed of a fiber layer mainly composed of inorganic fibers, and the plastic film used at least for the heat seal layer substantially generates gas when heated at 200 ° C. It is composed of a thermoplastic resin film having a melting point of 300 ° C. or higher at zero, and the vacuum heat insulating material has substantially zero gas generation when heated at 200 ° C., and the rate of increase in thermal conductivity after heating at 250 ° C. for 24 hours (at room temperature The rate of increase in thermal conductivity after heating at 250 ° C. for 24 hours with respect to the thermal conductivity of is required to be 10% or less.

  As described above, the core material is mainly composed of inorganic fibers as a material that can withstand continuous use in a wide range of arbitrary temperatures ranging from an ultra-low temperature of −100 ° C. or lower, more preferably −200 ° C. or lower to a high temperature of 200 ° C. or higher. It is necessary to consist of fiber layers.

  Examples of the form of the fiber layer include those obtained by forming the inorganic fibers into sheets, those obtained by laminating a plurality of sheets, or those obtained by simply collecting and laminating wool-like inorganic fibers without forming sheets. From the viewpoint of improving the handling properties when assembling the vacuum heat insulating material, it is preferable that the inorganic fiber is formed into a sheet, in particular, a sheet made by wet papermaking mainly using the inorganic fiber.

  When the fiber layer is composed of a wet papermaking sheet made of inorganic fibers, it is superior to the fiber layer obtained by collecting and compressing the above-mentioned wool-like inorganic fibers, and the sheet thickness is uniform. Therefore, there is no unevenness on the outer surface of the core material, and it becomes difficult to form a space between the jacket material and the core material, so that thermal convection is reduced, resulting in improved heat insulation performance and uniformity of heat insulation characteristics. In addition, since the inorganic fibers are easily arranged in the horizontal direction of the core material (perpendicular to the sheet stacking direction), the inorganic fibers aligned in the horizontal direction are heated against the heat conduction in the front and back directions of the core material. Insulation is hindered, resulting in improved thermal insulation performance. Moreover, when the thickness per sheet of the inorganic fiber wet papermaking sheet is made thin and laminated, the degree of arrangement of the inorganic fibers in the horizontal direction of the core material is further increased, and the heat insulation performance is further increased. improves.

  As the inorganic fiber, glass fiber, ceramic fiber, slag wool fiber, rock wool fiber, or the like can be used. However, when the fiber layer is composed of a sheet made by wet papermaking mainly using the inorganic fiber, the sheet is formed into a sheet. Although it is desirable to use a fine fiber having an average fiber diameter of about 4 μm or less in terms of ease, glass fiber is preferred because such a fine fiber is easily obtained industrially.

  The average fiber diameter of the inorganic fibers is preferably 2 μm or less, and more preferably 1 μm or less in order to reduce the joint area between the fibers, complicate the heat transfer path, and obtain high heat insulation performance. preferable. In addition, when the average fiber diameter is 2 μm or less, from the viewpoint of eliminating extra gas generation other than moisture during decompression or vacuum, as described above, when the fiber layer for the core material is constituted by a wet papermaking sheet made of inorganic fibers. Even when wet papermaking is performed only with inorganic fibers, it is easy to obtain sheet strength necessary for handling.

  Moreover, it is preferable that the average fiber diameter of the said inorganic fiber is 0.2 micrometer or more. When the average fiber diameter is less than 0.2 μm, when the fiber layer for the core material is composed of a wet paper-making sheet made of inorganic fibers, it is possible to make a sheet by wet paper-making, but the drainage is lowered and the productivity is lowered. As a result, the manufacturing cost increases, and there is a disadvantage that it is not suitable for practical use as an industrial product.

  As the glass fiber, for example, a short glass fiber obtained by melting and spinning an acid-resistant C glass, applying energy with a flame of a burner and blowing it, or a long glass fiber spun after melting the C glass is suitable. Used for. However, in the case of the above short glass fiber, if the flame energy of the burner is uneven or insufficient, it is mixed with the original short glass fiber, and a teardrop-like lump is attached to the end of the fiber. A small amount of granular or fibrous materials (shots) that have a relatively large size compared to the original short glass fibers, such as those that are partially thickened and those that remain thick fibers before being blown off with a burner There is a case.

  Glass fiber obtained by such a flame method or other methods such as centrifugation is formed in a columnar shape with a small surface area and is not branched (fibrillated) like pulp fibers. When the fiber layer for the core material is composed of a wet papermaking sheet made of glass fiber, the fiber is caught even if the fiber in the papermaking raw material liquid (papermaking slurry) is pulled by the forming wire running in a certain direction during wet papermaking. Thus, there is no inconvenience such as collapse of the sheet surface or opening of holes.

  Moreover, in the case of comprising a glass fiber wet papermaking sheet as the fiber layer for the core material, in order to eliminate the surface unevenness and the like, or to remove the glass shot and thick fibers that deteriorate the thermal conductivity, For example, the papermaking raw material liquid in which the glass fiber is dispersed in the dispersion medium is centrifuged and passed through a screen filter, etc., so that the granular material having a particle diameter of 30 μm or more and the fibrous material having a diameter of 10 μm or more in the papermaking raw material liquid. The content of the granular material having a particle size of 30 μm or more and the fibrous material having a diameter of 10 μm or more in the paper sheet is reduced to 0.1% by mass or less by removing the content of the material to substantially 0%. be able to.

  As described above, the jacket material includes a heat seal layer for vacuum-sealing made of a plastic film as the innermost layer, and a gas barrier layer for reflecting heat and preventing gas from permeating from a metal foil, a metal vapor-deposited film, or the like. And a laminate film having at least a two-layer structure including a protective layer for preventing physical damage from the outside made of a plastic film or the like as necessary (which may be further multilayered to enhance the function), and the heat It is necessary that the plastic film used at least for the sealing layer is made of a thermoplastic resin film (hereinafter, referred to as the thermoplastic resin film) having a melting point of 300 ° C. or higher with substantially no gas generation when heated at 200 ° C.

  The material of the thermoplastic resin film is preferably selected from polyimide, polyamideimide, and liquid crystal polymer. Films of polyimide, polyamideimide, and liquid crystal polymer have good adhesion to metal foil, and generally, copper foil is laminated and pressure-bonded as a main substrate of a flexible printed circuit board (FPC).

  As the thermoplastic resin film, in particular, when a film made of thermoplastic polyimide having a melting point of 350 ° C. or higher is used, the polyimide generates 19 ppm of water even when heated at 260 ° C., and gas generation is substantially zero. In addition, since no harmful gas is generated and it has a resistance to −269 ° C., the outer cover material is made of a laminate film in which the polyimide film is selected as a plastic film used at least for the heat seal layer and a metal foil is selected as the gas barrier layer. If the core material is constituted by a fiber layer composed of inorganic fibers, all the constituent materials of the vacuum heat insulating material can be made of a material that does not deteriorate even in an ultra-low temperature region of −200 ° C. or less, and −200 Over a long period of time in a wide range of temperature from ultra-low temperature below 200 ℃ to high temperature above 200 ℃ Te may be a vacuum heat insulator that can be used safely and satisfactorily.

  Specific examples of the thermoplastic resin film include thermoplastic polyimide (Aurum manufactured by Mitsui Chemicals), polyamideimide (Vilomax manufactured by Toyobo Co., Ltd.), liquid crystal polymer (Zyder manufactured by Solvey) and the like. In particular, when obtaining a vacuum heat insulating material that can be used even near 300 ° C., it is preferable to use thermoplastic polyimide (Aurum manufactured by Mitsui Chemicals, Inc.).

  The gas barrier layer is preferably a metal foil, and the metal foil is preferably an aluminum foil having a thickness of about 10 to 100 μm.

  For example, the laminate film as the outer cover material has a heat seal layer (innermost layer), a gas barrier layer (intermediate layer), and a protective layer (outermost layer), and the heat seal layer and the protective layer are plastic films (the thermoplastics). Resin film), when the gas barrier layer is composed of a metal foil (aluminum foil), the aluminum foil is laminated on the thermoplastic resin film, and the thermoplastic film is further laminated and heated to be integrated. A laminate film having a three-layer structure can be obtained.

  For example, when a thermoplastic polyimide film (Aurum PL450C manufactured by Mitsui Chemicals) and an aluminum foil are hot-pressed at a load of 5 MPa at 310 ° C. for 1 minute, the adhesive strength is 1.1 kgf / cm (test method JIS K6850). In the case of polyetherimide (PEI) and polyethersulfone (PES), it is 0.8 kgf / cm.

Next, examples of the present invention will be described in detail together with comparative examples.
(Manufacture of core material)
Using a raw material of 100% by mass of C glass short fibers having an average fiber diameter of 0.7 μm, wet papermaking was performed, and after hot air drying, a glass fiber sheet for core material having a thickness of 1 mm and a density of 0.16 g / cm ³ was obtained. Next, the sheet was cut to a specified size and heat-treated at 180 ° C. for 10 hours with a dryer, and then immediately laminated 10 sheets to a thickness of 10 mm and cut to a size of 200 mm × 200 mm to obtain a core material.

Example 1
A thermoplastic polyimide film (thickness 50 μm) having a melting point of 388 ° C. is laminated on the heat seal layer, an aluminum foil (thickness 10 μm) is laminated on the gas barrier layer, and a thermoplastic polyimide film (thickness 30 μm) having a melting point 388 ° C. is laminated on the protective layer. Was subjected to hot pressing at 310 ° C. for 1 minute, and this was cut into a size of 300 × 300 mm to obtain a jacket material (laminate film). The core material having a thickness of 10 mm obtained above was sandwiched between two outer cover materials and evacuated at 0.04 torr for 10 minutes, and then the peripheral portion was heat sealed to obtain a vacuum heat insulating material.

(Example 2)
A liquid crystal polymer film (thickness: 50 μm) having a melting point of 350 ° C. is laminated on the heat seal layer, an aluminum foil (thickness: 10 μm) is laminated on the gas barrier layer, and a thermoplastic polyimide film (thickness: 30 μm) having a melting point of 388 ° C. is laminated on the protective layer. Hot pressing was performed at 310 ° C. for 1 minute, and this was cut into a size of 300 × 300 mm to obtain an outer cover material (laminate film). The core material having a thickness of 10 mm obtained above was sandwiched between two outer cover materials and evacuated at 0.04 torr for 10 minutes, and then the peripheral portion was heat sealed to obtain a vacuum heat insulating material.

(Example 3)
A polyamideimide film (thickness 50 μm) having a melting point of 360 ° C. is laminated on the heat seal layer, an aluminum foil (thickness 10 μm) is laminated on the gas barrier layer, and a thermoplastic polyimide film (thickness 30 μm) having a melting point 388 ° C. is laminated on the protective layer. Hot pressing was performed at 310 ° C. for 1 minute, and this was cut into a size of 300 × 300 mm to obtain an outer cover material (laminate film). The core material having a thickness of 10 mm obtained above was sandwiched between two outer cover materials and evacuated at 0.04 torr for 10 minutes, and then the peripheral portion was heat sealed to obtain a vacuum heat insulating material.

(Comparative Example 1)
Polychlorotrifluoroethylene (thickness 50 μm) with a melting point of 210 ° C. for the heat seal layer, aluminum foil (thickness 10 μm) for the gas barrier layer, and polytetrafluoroethylene (PTFE) film (melting point 30 μm) with a melting point of 327 ° C. ), And heat-pressing was performed at 250 ° C. for 1 minute at a load of 5 MPa, and this was cut into a size of 300 × 300 mm to obtain a covering material (laminate film). At a press temperature of 310 ° C., polychlorotrifluoride ethylene melted out and the film shape could not be maintained, so the temperature was lowered. The core material having a thickness of 10 mm obtained above was sandwiched between two outer cover materials and evacuated at 0.04 torr for 10 minutes, and then the peripheral portion was heat sealed to obtain a vacuum heat insulating material.

(Comparative Example 2)
Polyphenylene sulfide (PPS) film (thickness 50 μm) with a melting point of 280 ° C. for the heat seal layer, aluminum foil (thickness 10 μm) for the gas barrier layer, and polytetrafluoroethylene (PTFE) film (thickness) with a melting point 327 ° C. for the protective layer 30 [mu] m), and a heat press was performed at 310 [deg.] C. for 1 minute at a load of 5 MPa, and this was cut into a size of 300 * 300 mm to obtain an outer cover material (laminate film). The core material having a thickness of 10 mm obtained above was sandwiched between two outer cover materials and evacuated at 0.04 torr for 10 minutes, and then the peripheral portion was heat sealed to obtain a vacuum heat insulating material.

  Next, with respect to the vacuum heat insulating materials of Examples 1 to 3 and Comparative Examples 1 and 2 obtained above, normal temperature thermal conductivity, thermal conductivity after heating at 250 ° C. for 24 hours, and shape change after heating were measured. did. The results are shown in Table 1.

From the results in Table 1, the following was found.
(1) The vacuum heat insulating material using thermoplastic polyimide for the heat seal layer of Example 1 has a normal temperature thermal conductivity of 0.0030 W / m · K, and is shaped even after heat treatment at 250 ° C. for 24 hours. There was no change, and no abnormality was observed in the seal part. The thermal conductivity at this time was not changed to 0.0030 W / m · K, and a heat-resistant vacuum heat insulating material was obtained.
(2) The vacuum heat insulating material using a thermoplastic liquid crystal polymer for the heat seal layer of Example 2 has a normal temperature thermal conductivity of 0.0030 W / m · K, and is shaped even after heat treatment at 250 ° C. for 24 hours. No abnormality was observed in the seal part. At this time, the thermal conductivity was hardly changed to 0.0032 W / m · K, and a heat-resistant vacuum heat insulating material was obtained.
(3) The vacuum heat insulating material using thermoplastic polyamideimide in the heat seal layer of Example 3 has a thermal conductivity of 0.0030 W / m · K at room temperature, and is shaped even after heat treatment at 250 ° C. for 24 hours. No abnormality was observed in the seal part. The thermal conductivity at this time was 0.0032 W / m · K, the same value as in Example 2, and a heat-resistant vacuum heat insulating material was obtained.
(4) The vacuum heat insulating material using thermoplastic polychlorotrifluoride ethylene for the heat seal layer of Comparative Example 1 had a thermal conductivity at room temperature of 0.0032 W / m · K. When the shape after the heat treatment at 250 ° C. for 24 hours was observed, the heat shrinkage was large and the flat plate shape was not maintained. Further, the seal portion was peeled off, and air entered into the inside to increase the thickness. The shape change was large and the thermal conductivity could not be measured. Therefore, it is unsuitable as a high temperature heat resistant vacuum heat insulating material.
(5) The vacuum heat insulating material using thermoplastic polyphenylene sulfide for the heat seal layer of Comparative Example 2 had a thermal conductivity at room temperature of 0.0030 W / m · K. When the shape after heat treatment at 250 ° C. for 24 hours was observed, it seemed that there was no change in shape and peeling of the seal part, but there was an inflow of air, and the initial thickness of the vacuum heat insulating material was 8.7 mm. It was thick. The thermal conductivity at this time was 0.051 W / m · K, which is close to the thermal conductivity of a single glass fiber, and was found to be inappropriate as a heat-resistant vacuum heat insulating material.

Claims (3)

  In a vacuum heat insulating material in which a core material is packed with a jacket material and the inside is decompressed and sealed, the jacket material is composed of a heat seal layer made of a plastic film as an innermost layer, a metal foil, a metal vapor deposition film, and the like. It consists of a laminate film having at least a two-layer structure including a gas barrier layer and, if necessary, a protective layer made of a plastic film or the like. The plastic film used at least for the heat seal layer has substantially no gas generation when heated at 200 ° C. It consists of a thermoplastic resin film having a melting point of 300 ° C. or higher at zero, the core material is composed of a fiber layer mainly composed of inorganic fibers, and the vacuum heat insulating material has substantially no gas generation when heated at 200 ° C. The rate of increase in thermal conductivity after heating at 24 ° C. for 24 hours (the rate of increase in thermal conductivity after 24 hours of heating at 250 ° C. for normal temperature) is 10% or less. Vacuum heat insulating material according to claim Rukoto.   2. The vacuum heat insulating material according to claim 1, wherein the thermoplastic resin film is made of polyimide, polyamideimide or liquid crystal polymer.   The vacuum heat insulating material according to claim 2, wherein the thermoplastic resin film is a thermoplastic polyimide having a melting point of 350 ° C or higher.