JP2016124186A - Laminate and vacuum heat insulation material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate capable of efficiently reducing heat bridge, excellent in processability and inhibiting generation of pinhole or crack.SOLUTION: There is provided a laminate having at least one polymer layer, a gas barrier layer and at least one polymer layer in this order arranged via adhesive layers between layers, the gas barrier layer has heat resistance of 650 K/W or more and Young modulus of 100 GPa or more and a position of a neutral axis represented by the following formula is positioned in the gas barrier layer. where y is a distance from an upper face in compression side during blending to the natural axis, Ei is Young modulus of the i-th layer. Si is cross section primary moment of the i-th layer, Ai is cross section area of the i-th layer and n is the number of layers constituting the laminate and the integer of 5 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminate and a vacuum heat insulating material using the laminate as an exterior material. In particular, the present invention relates to a laminate and a vacuum heat insulating material that can effectively reduce heat bridges, have excellent workability, and suppress the generation of pinholes and cracks.

  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 used for maintaining the degree of vacuum inside the vacuum heat insulating material is composed of a laminate of aluminum foil and plastic in order to prevent gas from entering from the outside. However, since aluminum has a high thermal conductivity of 237 W / m · K, the vacuum heat insulating material using the above-described laminated body as an exterior material is a heat in which heat from the surroundings flows around the exterior material part. There was a problem that the bridge was big.

  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 Application Laid-Open No. 61-1255577 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. Furthermore, in a laminate of metal foil and plastic, there is a large difference in Young's modulus between the metal foil and plastic, and thus there may be a problem in workability in the bending process when manufacturing the vacuum heat insulating material. In addition, stress concentrates on the gas barrier layer and pinholes and cracks are generated in the exterior material. As a result, there is a problem that the gas barrier property is deteriorated. 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, the present invention has been made in view of the above circumstances, and a laminated body in which heat bridges can be reduced, processability is excellent, and generation of pinholes and cracks is suppressed, and a vacuum heat insulating material using the same. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have used a material having a predetermined thermal resistance and Young's modulus for the gas barrier layer of the laminate used as the exterior material of the vacuum heat insulating material. It has been found that the above problem can be solved by controlling the layer configuration in which the target neutral axis is located in the gas barrier layer, and the present invention has been completed.

  That is, the object is a laminate having at least one polymer layer, a gas barrier layer, and at least one polymer layer in this order, and disposed between each layer via an adhesive layer, wherein the gas barrier layer includes It is achieved by a laminate having a thermal resistance of 650 K / W or more and a Young's modulus of 100 GPa or more, and a neutral axis position represented by the following formula is located in the gas barrier layer.

  Where y is the distance from the compression-side upper surface to the neutral axis during bending, Ei is the Young's modulus of the i-th layer, Si is the cross-sectional primary moment of the i-th layer, and Ai is the i-th layer It is a cross-sectional area of the layer, and n is the number of layers constituting the laminate, and is an integer of 5 or more.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body which can reduce heat bridge effectively, is excellent in workability, the generation | occurrence | production of the pinhole and the crack, and the vacuum heat insulating material using the same are provided.

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

The present invention is a laminate having at least one polymer layer, a gas barrier layer, and at least one polymer layer in this order, and disposed between each layer via an adhesive layer,
The gas barrier layer has a thermal resistance of 650 K / W or more and a Young's modulus of 100 GPa or more;
The laminate is characterized in that the neutral axis represented by the following formula is located in the gas barrier layer:

  Where y is the distance from the compression-side upper surface to the neutral axis during bending, Ei is the Young's modulus of the i-th layer, Si is the cross-sectional primary moment of the i-th layer, and Ai is the i-th layer It is a cross-sectional area of the layer, and n is the number of layers constituting the laminate, and is an integer of 5 or more.

  According to the present invention, the mechanical neutral axis of the laminate as the vacuum insulation material is positioned in the gas barrier layer. With such a configuration, the gas barrier layer is not easily broken even during compression or bending, and pinholes and cracks are less likely to occur. Furthermore, by controlling the thermal resistance and Young's modulus of the gas barrier layer within a predetermined range, the workability is excellent and the heat bridge of the exterior material can be effectively reduced.

  Conventionally, in order to maintain a high degree of vacuum inside the vacuum heat insulating material, an inexpensive and high gas barrier aluminum foil has been used as a gas barrier layer. However, since aluminum has a high thermal conductivity among metals, there is a problem that heat flows around the exterior material portion of the vacuum heat insulating material (heat bridge). Further, when manufactured by a rolling method, it is difficult to make the thickness 7 μm or less due to problems of pinholes and tensile strength, and as a result, there is a limit to increasing the thermal resistance.

  In order to solve the problem, an alternative to a deposited film or a metal foil with low thermal conductivity has been considered. However, the deposited film has a problem that the gas barrier property for maintaining the degree of vacuum inside the vacuum heat insulating material is insufficient. Moreover, even if it changes to metal foil with another low heat conductivity, it is difficult to manufacture foil of 10 micrometers or less with a rolling method, and the Young's modulus of metal foil is the Young's modulus of the plastic laminated with metal foil, Due to the great difference, there are problems such as problems in workability in the bending process during the manufacture of the vacuum heat insulating material, and stress concentration on the gas barrier layer and tearing.

  Therefore, in the present invention, a layer structure is designed such that a material having high thermal resistance is used for the gas barrier layer of the laminate used as the exterior material, and a dynamic neutral axis is located in the gas barrier layer. The neutral shaft is an axis that is not loaded when bent, and the load increases as the distance from the neutral shaft increases. According to the present invention, since the stress applied to the gas barrier layer can be minimized even during compression and bending, a laminate and a vacuum heat insulating material having excellent bending resistance can be produced.

  Therefore, the vacuum heat insulating material using the laminate of the present invention can reduce heat bridges and is excellent in workability, and the occurrence of pinholes and cracks is suppressed. For this reason, the vacuum heat insulating material using the laminated body of this invention is useful as vacuum heat insulating materials, such as a refrigeration 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 7 and a gas adsorbent 8 are included so as to be sandwiched from both sides by a laminate 2 as an exterior material. Here, the laminate 2 has at least a gas barrier layer 4 and at least one layer on each side, preferably three or more layers in total (three layers in FIG. 1), and polymer layers 3, 5, 6 to be laminated. It is the laminated body (laminate film) which has. The gas barrier layer 4 and the polymer layers 3, 5, 6 are bonded to each other via an adhesive layer (not shown). As described above, by providing the gas barrier layer 4 having a thermal resistance of a certain level or more, the amount of heat flowing from the surroundings through the stacked body 2 can be kept low. For this reason, a heat bridge can be efficiently suppressed and prevented by using the laminated body 2 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 2, and the core material 7 and the gas adsorbed in the laminate 2. In this state, the agent 8 is accommodated, and 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) 9 in which the laminates are joined to each other (end portions) around the laminate 2. As shown in FIG. 1B, the joint portion 9 is bent toward the vacuum heat insulating material main body to become a vacuum heat insulating material product.

  Hereinafter, each member of the vacuum heat insulating material of the present invention will be described. In addition, since this invention has the characteristics in the laminated body as an exterior material, about the other member, the member similar to the past can be used, and it is not limited to the following form.

(Exterior material)
As shown in FIG. 2, the exterior material has at least one polymer layer (11), a gas barrier layer (13), and at least one polymer layer (15, 17) in this order, and these layers are bonded. It is a laminated body laminated | stacked through a layer (12,14,16). In the laminate of the present invention, the gas barrier layer has a thermal resistance of 650 K / W or more. Further, in a laminate having a gas barrier layer having a Young's modulus of 100 GPa or more, the neutral axis of the laminate is located in the gas barrier layer (FIG. 2).

  In the present invention, the core material and the gas adsorbent are enclosed by a pair of outer packaging materials having gas barrier properties, and the inside is decompressed and sealed to form a vacuum heat insulating material. At least one of the laminates having the properties consists of the above laminate. It is preferable that both of the exterior materials are composed of the above laminate.

  At this time, if the total number of layers constituting the laminate is n layers, and the m-th layer is a gas barrier layer from the upper surface of the laminate on the compression side when bent, 1, 3, ..., the m-2th layer, and the m + 2, m + 4,... Nth layer are polymer layers. From the upper surface of the laminate on the compression side at the time of bending, the 2, 4,..., M−1 th layer and the m + 1, m + 3.

  Under the present circumstances, n is an integer greater than or equal to 5, Preferably it is an integer of 5-13. m is an integer of 3 or more, and preferably an integer of 3 to 7.

  The position of the neutral axis can be calculated according to the following formula from the Young's modulus and thickness of each polymer layer and gas barrier layer.

  Where y is the distance from the compression-side upper surface to the neutral axis during bending, Ei is the Young's modulus of the i-th layer, Si is the cross-sectional primary moment of the i-th layer, and Ai is the i-th layer It is a cross-sectional area of the layer, and n is an integer of 5 or more.

  Although the position of the neutral shaft does not depend on the bending compression conditions, the position of the neutral shaft when bending is performed under the conditions described in the examples described later can be employed.

  In the laminate of the present invention, the position of the neutral axis is determined by arranging the material, thickness, number of layers, stacking order, etc. of the polymer layers stacked on both sides of the gas barrier layer so as to balance the stress. It can be controlled to be present in the gas barrier layer. That is, the layer configuration can be designed from the Young's modulus and thickness of each layer.

  In FIG. 1, the polymer layers 3, 5, and 6 on both sides of the gas barrier layer 4 are shown in a single layer and a two-layer form, respectively, but the polymer layers may exist in a single-layer form. Alternatively, two or more kinds of laminated forms may be present.

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

  As described above, the problem of heat bridge is solved by using the laminate according to the present invention. Considering the effect of suppressing heat bridge, the laminate is preferably thin and has low thermal conductivity. Considering the above points, the thermal resistance of the gas barrier layer is required to have a certain value or more, and the gas barrier layer used in the laminate of the present invention has a thermal resistance (R) of 650 K / W or more. The gas barrier layer preferably has a thermal resistance (R) of 750 K / W or higher, more preferably has a thermal resistance (R) of 1000 K / W or higher, and has a thermal resistance (R) of 1500 K / W or higher. Is more preferable. If the thermal resistance of the gas barrier layer is less than 650 K / W, the effect of suppressing the heat bridge cannot be obtained sufficiently. In addition, since it is so preferable that the thermal resistance of a gas barrier layer is high, an upper limit is not specifically limited, Usually, 20,000 K / W or less is enough, and it may be 10,000 K / W or less. In particular, a laminated body using a gas barrier layer having a thermal resistance of 650 K / W or more and a thickness of 10 μm or less is a heat bridge while ensuring good workability as compared with the case of using a conventional aluminum foil. Can be more effectively suppressed / prevented. In this specification, the thermal resistance of the gas barrier layer refers to the thermal resistance perpendicular to the thickness direction with respect to the gas barrier layer per unit area, and the thermal resistance (R) (K / W) is the value of the gas barrier layer. It can be obtained from the thickness (d) (m) and the thermal conductivity (λ) (W / m · K), and specifically, is calculated by the following formula.

  The thickness (d) of the gas barrier layer is not particularly limited, but is preferably 0.1 to 6 μm. More preferably, it is 0.1-4 micrometers, More preferably, it is 0.3-3 micrometers, Most preferably, it is 0.5-2 micrometers. If the thickness of the gas barrier layer is 0.1 μm or more, sufficient gas barrier properties can be secured. Moreover, since heat resistance will become high enough if it is 6 micrometers or less, the heat bridge which heat flows along a vacuum heat insulating material surface can be suppressed / prevented more effectively, and heat insulation performance can be improved. Furthermore, since it is excellent in workability such as flexibility, the joint portion of the exterior material can be easily adhered to the vacuum heat insulating material body. In addition, in this specification, the thickness of a gas barrier layer intends the maximum thickness.

  Further, as described above, the gas barrier layer of the laminate of the present invention has a Young's modulus of 100 GPa or more. A metal having a Young's modulus of 100 GPa or more is hard and easily broken, and a laminate using such a metal as a gas barrier layer is greatly deteriorated in gas barrier properties due to breakage of the laminate due to bending or generation of cracks or pinholes. It is easy to end up. However, in the laminate of the present invention, by controlling the position of the neutral axis in the gas barrier layer, the bending resistance is excellent even when the gas barrier layer having a Young's modulus of 100 GPa or more is used. A laminate can be obtained.

  The material of the gas barrier layer is not particularly limited as long as it has the specific heat resistance and Young's modulus described above. For example, iron (Young's modulus: about 192 GPa), copper (Young's modulus: about 130 GPa), nickel (Young's modulus: about 200 GPa), SUS (Young's modulus: about 199 GPa), titanium (Young's modulus: about 107 GPa), platinum (Young Rate: about 168 GPa), cobalt (Young's modulus: about 209 GPa), carbon steel (Young's modulus: about 206 GPa), and / or metal foils composed of alloys containing these metals, nickel, copper, oxidation A vapor deposition film such as silicon, alumina, magnesium oxide, titanium oxide and / or a metal vapor deposition film including an alloy vapor deposition film containing these metals can be used. Among these, it is preferable to use a metal foil because it can be easily formed into a thin film and has excellent gas barrier properties even if it is thin.

  In the laminate of the present invention, the gas barrier layer is preferably an electrolytic metal foil. Among metal foils, the electrolytic metal foil can be easily formed into a thin film and has excellent gas barrier properties even if it is thin. Therefore, the joint can be easily adhered to the vacuum heat insulating material body. Therefore, even when the joint is bent, the heat bridge that effectively suppresses and prevents the heat bridge that flows along the surface of the vacuum insulation material improves heat insulation performance, and at the same time, highly reliable vacuum insulation material with excellent gas barrier properties Can provide.

  The method for producing the electrolytic metal foil 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.

  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 metal foil is manufactured by the rolling method or the electrolytic method can be identified by the following method. That is, the metal foil produced by the rolling method has large crystal grains and is stretched in the surface direction of the foil by the rolling operation, whereas the metal foil produced by the electrolytic method has fine crystal grains. And it has grown in the thickness direction of the foil. Moreover, the electrolytic metal foil has a larger surface roughness than the rolled metal foil due to its manufacturing process. Preferably, the surface roughness (Rz) of the electrolytic metal foil is 0.05 μm to 3 μm, more preferably 0.05 μm to 2.5 μm, and still more preferably 0.05 μm to 2 μm.

  The composition of the metal foil may be composed of any material and is not particularly limited. For example, a metal having a Young's modulus of 100 GPa or more, such as nickel, iron, or copper, can be preferably used. The metal foil may be a metal foil composed of a single metal or an alloy foil composed of an alloy of two or more metals. Preferably, the metal foil includes nickel. That is, the metal foil is preferably a nickel foil or an alloy foil containing nickel.

  In addition, the alloy composition when the 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 metal foil is a nickel alloy foil (alloy foil containing nickel), nickel is 1% by weight or more with respect to the metal foil (total weight of the metal constituting the metal foil). It is preferably 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 metal foil (total weight of the metal which comprises metal foil). With such a composition, sufficiently low thermal conductivity, sufficiently high thermal resistance (that is, excellent heat insulation) and high gas barrier properties can be exhibited.

  A gas barrier layer is laminated | stacked with a polymer layer via the contact bonding layer on the both sides | surfaces, and the laminated body which concerns on this invention is obtained. In addition, the composition of the polymer layer is not particularly limited, but usually, as a polymer layer (polymer layer 6 in FIG. 1) on the inner side (the side where the core material and the gas adsorbent are accommodated) than the gas barrier layer, the heat weldability It is preferable to include a film having Moreover, it is preferable that the polymer layer (layer represented by 3 in FIG. 1) on the outer side (side in contact with the outside air) than the gas barrier layer is a film having a surface protective effect (surface protective film). Further, it is preferable to further provide a polymer layer (a layer represented by 5 in FIG. 1) which is a film having a surface protecting effect on the inner side of the gas barrier layer.

  Preferably, in the laminate of the present embodiment, a polymer layer 1 having a Young's modulus of 5 to 5 MPa and a Young's modulus of 3 to 5 GPa, at least a Young's modulus of 5 to 100 MPa and a heat sealability, is provided through an adhesive layer between the layers. A gas barrier layer having a Young's modulus of 100 to 300 GPa and a polymer layer 3 having a Young's modulus of 1 to 3 GPa are laminated in this order. With such a configuration, it is easy to balance the stress applied to the laminate, so that the effects of the invention can be significantly obtained.

  Under the present circumstances, when using the said laminated body as an exterior material, it is preferable that the polymer 1 is arrange | positioned inside (side in which the core material and the gas adsorbent are accommodated).

  The polymer having heat sealability used as the polymer layer 1 (heat welding film) is not particularly limited as long as it can be bonded by a normal heat seal method. Examples of the material constituting the polymer layer 1 (thermal welding film) include polyolefins such as low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and polypropylene, ethylene-vinyl acetate copolymers, and ethylene-methacrylic acid copolymers. Examples thereof include thermoplastic resins such as a polymer, an ethylene-acrylic acid ester copolymer, an ethylene-acrylic acid ester copolymer, and polyacrylonitrile. Among these, polyethylene is preferably used from the viewpoints of cost, melting temperature, and laminate strength. In addition, the said material may be used independently or 2 or more types of mixtures may be sufficient as it. In addition, the polymer layer 1 (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 polymer layer 1 (heat welding film) may be an unstretched film, or may be stretched uniaxially or biaxially.

  The thickness of the polymer layer 1 (heat welding film) is not particularly limited, but is preferably 30 to 80 μm. If it is 30 micrometers or more, it will be easy to control so that the neutral axis of a laminated body may be located in a gas barrier layer. Moreover, since sufficient adhesion strength can be obtained at the time of heat sealing, it is preferable. If the thickness of the polymer layer 1 (heat welding film) is 80 μm or less, the processability such as flexibility is excellent. 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.

  The Young's modulus of the polymer layer 1 (heat welding film) is not particularly limited, but is preferably 5 to 100 MPa. If the Young's modulus is 5 MPa or more, it is easy to control so that the neutral axis of the laminate is positioned in the gas barrier layer. If the Young's modulus is 100 MPa or less, the processability such as flexibility is excellent. In addition, when the heat-sealing film has a laminated structure of two or more layers, it is preferable that at least one heat-sealing film has the above Young's modulus, and all the heat-sealing films have the above Young's modulus. It is more preferable.

  As the polymer layer 2, a polymer layer having a Young's modulus of 3 to 5 GPa is preferably used. By adopting a configuration in which the gas barrier layer is sandwiched between the polymer layer 2 having a Young's modulus of 3 to 5 GPa and the polymer layer 3 (surface protective film) described later, the neutral axis of the laminate can be easily positioned on the gas barrier layer. Can be adjusted. Examples of the material constituting the polymer layer 2 include polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), and polystyrene (PS). ), Polyolefin, 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. Among these, from the viewpoints of cost, gas barrier properties, etc., it is preferable to use polyethylene terephthalate (PET) or ethylene vinyl alcohol copolymer (EVOH). 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 polymer layer 2 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 polymer layer 2 may be an unstretched film or may be uniaxially or biaxially stretched, but is preferably a stretched film. Stretching increases the strength and increases the Young's modulus. Moreover, it can be made into a thin film and workability can be improved.

  The thickness of the polymer layer 2 is not particularly limited, but is preferably 10 to 30 μm. If it is the said range, it will be easy to balance the stress concerning a laminated body, and it will be easy to control so that the neutral axis of a laminated body may be located in a gas barrier layer. Moreover, it is excellent in workability, such as flexibility. In addition, when the polymer layer 2 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.

  In addition, when the polymer layer 2 has a laminated structure of two or more layers, it is preferable that at least one layer has the above Young's modulus, and it is more preferable that all the layers have the above Young's modulus.

  The polymer layer 3 (surface protective film) is not particularly limited, and materials similar to those usually used as a surface protective film for exterior materials can be used. As a material constituting the surface protective film, for example, polyamide (nylon) (PA) such as nylon-6 and nylon-66 has high piercing characteristics from the viewpoint of suppressing bag breakage of the exterior material. 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 polymer layer 3 may be an unstretched film or may be uniaxially or biaxially stretched, but is preferably a stretched film. Stretching increases the strength and increases the Young's modulus. Moreover, it can be made into a thin film and workability can be improved. Furthermore, the effect which protects from a stab etc. is heightened.

  The thickness of the polymer layer 3 (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 30 μm. If it is 10 micrometers or more, the protective effect of a gas barrier layer will fully be acquired and a crack etc. will not generate | occur | produce easily. Moreover, if it is 30 micrometers or less, it is excellent in workability, such as a flexibility. In addition, when the polymer layer 3 (surface protective 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 Young's modulus of the polymer layer 3 (surface protective film) is not particularly limited, but is preferably 1 to 3 GPa. If the Young's modulus is 1 GPa or more, it is easy to control so that the neutral axis of the laminate is located in the gas barrier layer. If the Young's modulus is 3 GPa or less, the processability such as flexibility is excellent. In addition, when the polymer layer 3 (surface protective film) has a laminated structure of two or more layers, it is preferable that at least one surface protective film has the above Young's modulus, and all the surface protective films have the above Young's modulus. It is more preferable to have a rate.

  Adhesive layers are provided between the polymer layer and the gas barrier layer and between each polymer layer. The adhesive layer adheres the polymer layer and the gas barrier layer, or the polymer layers to each other. Although it does not restrict | limit especially as an adhesive agent used for a contact bonding layer, A urethane type adhesive agent, a polyacrylate ester type adhesive agent, a cyanoacrylate type adhesive agent, a silicone type adhesive agent etc. are mentioned. Among these, urethane adhesives are preferable, and it is particularly preferable to use a two-component curable isocyanate adhesive that is used by mixing a main agent (polyol) and a curing agent (polyisocyanate). When a urethane-based adhesive is used, pinholes are hardly generated even when bending is performed, and the heat insulating effect of the vacuum heat insulating material can be maintained for a long period of time. The adhesive used for each adhesive layer may be the same or different.

  The Young's modulus of the adhesive layer is not particularly limited, but is preferably 10 MPa or less from the viewpoint of easily controlling the position of the neutral axis of the laminate.

  Moreover, the thickness of the adhesive layer is not particularly limited, but is, for example, 1 to 5 μm. If it is the said range, it will become easy to control so that the neutral axis of a laminated body may be located in a gas barrier layer. The thickness of each adhesive layer may be the same or different.

  The thickness of the laminate is not particularly limited. Specifically, the thickness of the laminate is preferably 40 to 210 μm. If it is a laminated body as described above, the heat bridge can be more effectively suppressed / prevented and the heat insulation performance can be improved, and the gas barrier property and workability are also excellent.

The laminate according to the present invention is preferably excellent in gas barrier properties. Specifically, the water vapor permeability of the laminate is preferably 1 × 10 ⁻³ (g / m ² · day) or less, and preferably 5 × 10 ⁻⁴ (g / m ² · day) or less. Is more preferable. If the water vapor permeability of the laminate is 1 × 10 ⁻³ (g / m ² · day) or less, the degree of vacuum inside the vacuum heat insulating material using this as an exterior material can be maintained for a long time. In addition, since the water vapor permeability of a laminated body is so preferable that it is low, a minimum is not specifically limited, However, Usually ^1x10 < ^-7 > (g / m < ² > * day) or more is enough. The water vapor permeability after bending is preferably 1 × 10 ⁻³ (g / m ² · day) or less, and more preferably 5 × 10 ⁻⁴ (g / m ² · day) or less. . In this specification, the water vapor transmission rate of a laminated body and the water vapor transmission rate after bending of a laminated body are measured by the method described in the following Example.

  Moreover, when the laminated body which concerns on this invention considers heat insulation, it is preferable that heat conductivity is low. And it is preferable that the vacuum heat insulating material which used this laminated body as an exterior material also has low heat 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 is measured by the method as described in the following Example.

  Moreover, the thermal conductivity difference of the vacuum heat insulating material before and after the accelerated deterioration test is preferably 10 mW / m · K or less, more preferably 5 mW / m · K or less, and further preferably 2 mW / m · K or less. It is particularly preferably 1.5 mW / m · K or less. In this specification, the thermal conductivity difference of the vacuum heat insulating material before and after the accelerated deterioration test of the vacuum heat insulating material is measured by the method described in the following examples.

  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 laminates are prepared, one laminate (laminate film) is folded, and the heat-welded films located at the ends of the opposite laminates are thermally welded together to form a bag-like 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 laminated bodies (laminate films) are arranged so that the two face each other, and a heat-sealing film located at the end of each laminated body is thermally welded to obtain a bag-like exterior material. 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 laminate of the present invention can effectively suppress the generation of heat bridges, has excellent workability, and suppresses the generation of pinholes and cracks. Therefore, the vacuum heat insulating material using the laminate of the present invention as an exterior material has a 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 / thermal insulation box. It can be suitably applied to equipment that needs to be maintained.

  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
In order from the surface protective film (upper surface) to the heat-welded film (lower surface), biaxially stretched nylon (thickness: 25 μm; Young's modulus: 1.4 GPa) as the polymer layer 3 and nickel electrolytic foil (thickness: 1 μm; as the gas barrier layer). Thermal resistance: 11,173 K / W; Young's modulus: 200 GPa), biaxially stretched ethylene vinyl alcohol copolymer (thickness: 12 μm; Young's modulus: 4 GPa) as polymer layer 2, linear low density as polymer layer 1 A polyethylene film (thickness: 50 μm; Young's modulus: 10 MPa), and each layer as an adhesive layer is bonded by dry lamination via a two-component curable isocyanate adhesive (thickness: 3 μm; Young's modulus: 3.1 MPa). It was.

  A laminate of short fiber glass wool was used as a core material, and quicklime stored in a breathable outer packaging material was used as a gas adsorbent. Using the laminate 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 12 mm was produced.

Example 2
A laminate 2 and a vacuum heat insulating material 2 were produced in the same manner as in Example 1 except that the thickness of the nickel electrolytic foil was changed to 3 μm.

Example 3
In Example 1, the laminate 3 and the polymer layer 2 were formed in the same manner except that the biaxially stretched ethylene vinyl alcohol copolymer was changed to biaxially stretched polyethylene terephthalate (thickness: 12 μm; Young's modulus: 3.4 GPa). The vacuum heat insulating material 3 was produced.

Example 4
The laminate 4 and the vacuum heat insulating material 4 were produced in the same manner as in Example 3 except that the thickness of the nickel electrolytic foil was changed to 3 μm.

Comparative Example 1
In Example 3 above, the structure of the laminate was sequentially biaxially stretched nylon (thickness: 25 μm; Young's modulus: 1.4 GPa), biaxially stretched polyethylene terephthalate (thickness: 12 μm; Young's modulus: 3.4 GPa) from top to bottom. ), A rolled aluminum foil (thickness: 7 μm; thermal resistance: 602 K / W; Young's modulus: 69 GPa) as a gas barrier layer, and a linear low density polyethylene film (thickness: 50 μm; Young's modulus: 10 MPa). Thus, the laminate 5 and the vacuum heat insulating material 5 were produced.

Comparative Example 2
In Example 3 above, the structure of the laminate was biaxially stretched nylon (thickness: 25 μm; Young's modulus: 1.4 GPa) and biaxially stretched polyethylene terephthalate (thickness: 12 μm; Young's modulus: 3.4 GPa) in order from the upper surface to the lower surface. The laminate 6 and the vacuum heat insulating material 6 were produced by the same method except that VM-PET (thickness: 12 μm) and a linear low density polyethylene film (thickness: 50 μm; Young's modulus: 10 MPa) were used. Here, as VM-PET, a 12 μm-thick polyethylene terephthalate film having an Al vapor deposition film of 30 nm in thickness was used and laminated so that the Al vapor deposition film was on the biaxially stretched polyethylene terephthalate side.

Comparative Example 3
In Example 3 above, the structure of the laminate was sequentially biaxially stretched polyethylene terephthalate (thickness: 12 μm; Young's modulus: 3.4 GPa), biaxially stretched nylon (thickness: 25 μm; Young's modulus: 1.4 GPa) from the top surface to the bottom surface. The same except that the nickel electrolytic foil (thickness: 1 μm; thermal resistance: 11,173 K / W; Young's modulus: 200 GPa) and the linear low density polyethylene film (thickness: 50 μm; Young's modulus: 10 MPa) as the gas barrier layer The laminated body 7 and the vacuum heat insulating material 7 were produced by the method.

  The following evaluation was performed about the laminated bodies 1-7 produced above and the vacuum heat insulating materials 1-7.

<Evaluation 1: Neutral axis position>
About the position of the neutral axis of the laminated bodies 1-7 produced in the said Examples 1-4 and Comparative Examples 1-3, it computed using the following formula. The position of the neutral axis is indicated by the distance (μm) from the surface protective film side (upper side).

Here, y: distance from the compression upper surface to the neutral axis (μm) during bending, Ei: Young's modulus (Pa) of the i-th layer, Si: first moment of section (μm ³ ) of the i-th layer, Ai : The cross-sectional area (μm ³ ) of the i-th layer. The results are shown in Table 1 below.

  Bending compression was performed by folding the laminate in half so that the surface was in contact with the upper surface (biaxially stretched nylon side surface) of the laminate, and then opening it once and bending it further to the opposite side.

<Evaluation 2: Water vapor permeability before and after bending>
About the laminated bodies 1-7 produced in the said Examples 1-4 and Comparative Examples 1-3, the water-vapor permeability (g / m < ² > * day) before and behind bending was measured according to the following method. Note that “after bending” means that the sample measured before bending is bent into a cross. The water vapor transmission rate was measured at a temperature of 40 ° C. and a relative humidity of 90% RH using Aquatran (manufactured by MOCON) according to ISO 15106-3. The results are shown in Table 1 below.

<Evaluation 3: Thermal conductivity and thermal resistance of gas barrier layer>
About the gas barrier layer (metal part) used in the above Examples 1 to 4 and Comparative Examples 1 to 3, the thermal diffusivity in the in-plane direction was measured using Thermowave Analyzer (manufactured by Nissan Arc Co., Ltd.), and the specific heat of each metal The thermal conductivity (W / m · K) was calculated from the density. Moreover, thermal resistance (K / W) was computed from the obtained heat conductivity and thickness. The results are shown in Table 1 below.

<Evaluation 4: Heat insulation performance of vacuum heat insulating material>
About the vacuum heat insulating materials 1-7 produced in the said Examples 1-4 and the comparative examples 1-3, using HFM436 (made by NETZSCH), the heat after implementation of the acceleration test equivalent to 10 years by an initial stage and a constant temperature and humidity chamber The conductivity (mW / m · K) was measured, and the heat insulation performance was compared from the difference. The results are shown in Table 1 below.

<Evaluation 5: Heat bridge performance of vacuum insulation>
About the vacuum heat insulating materials 1-7 produced in the said Examples 1-4 and Comparative Examples 1-3, using a heat flow meter HFM436 (made by NETZSCH), two vacuum heat insulating materials are inserted from both sides, and a measurement part Arranged so that two vacuum insulation materials hit each other at the center, the thermal conductivity (mW / m · K) was measured, and the heat bridge performance was compared. The results are shown in Table 1 below.

  As shown in Table 1 above, the laminates of Examples 1 to 4 each having a gas barrier layer having a predetermined thermal resistance and Young's modulus and the mechanical neutral axis of the laminate being located in the gas barrier layer are the gas barrier layers. Compared with the laminated body of the comparative example 1 in which the thermal resistance of less than 650 K / W, the effect which suppresses the influence of a heat bridge is high. In addition, compared with the laminates of Comparative Examples 2 and 3 in which the position of the mechanical neutral axis is located in a layer other than the gas barrier layer, even after folding, excellent gas barrier properties equivalent to those before folding are exhibited, and high It was found that durability (bending resistance) was obtained.

1 ... Vacuum insulation
2 ... Laminated body,
3, 5, 6 ... polymer layer,
4 ... Gas barrier layer,
7 ... Core material,
8 ... Gas adsorbent,
9: Joining part (seal part),
11, 15, 17 ... polymer layer,
12, 14, 16 ... adhesive layer,
13: Gas barrier layer.

Claims (10)

A laminate having at least one polymer layer, a gas barrier layer, and at least one polymer layer in this order, and disposed between each layer via an adhesive layer,
The gas barrier layer has a thermal resistance of 650 K / W or more and a Young's modulus of 100 GPa or more;
The laminated body characterized in that the neutral axis represented by the following formula is located in the gas barrier layer:
Where y is the distance from the compression-side upper surface to the neutral axis during bending, Ei is the Young's modulus of the i-th layer, Si is the cross-sectional primary moment of the i-th layer, and Ai is the i-th layer It is a cross-sectional area of the layer, and n is the number of layers constituting the laminate, and is an integer of 5 or more.   The laminate according to claim 1, wherein the gas barrier layer is made of a metal foil.   The laminate according to claim 2, wherein the metal foil is an electrolytic metal foil.   The laminated body of Claim 2 or 3 whose thickness of the said metal foil is 0.1-6 micrometers.   The laminated body of any one of Claims 2-4 whose said metal foil is nickel foil.   The laminate is a polymer layer 1 having at least a Young's modulus of 5 to 100 MPa and heat sealability, a polymer layer 2 having a Young's modulus of 3 to 5 GPa, and a Young's modulus of 100 to 300 GPa through an adhesive layer between the layers. The laminated body of any one of Claims 1-5 laminated | stacked in order of a certain gas barrier layer and the polymer layer 3 whose Young's modulus is 1-3 GPa.   The laminate according to claim 6, wherein the polymer layer 1 is polyethylene.   The laminate according to claim 6 or 7, wherein the polymer layer 2 is polyethylene terephthalate or ethylene vinyl alcohol copolymer.   The laminate according to any one of claims 6 to 8, wherein the polymer layer 3 is nylon.   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. The vacuum heat insulating material whose at least one of is the laminated body of any one of Claims 1-9.