JP2018189220A - Exterior material for vacuum heat insulation material - Google Patents

Abstract

The present invention provides an exterior material for a vacuum heat insulating material that prevents a degree of vacuum from being lowered due to outgas generated from a sealant layer by heating and prevents deterioration (rise) of heat conduction. An exterior material for a vacuum heat insulating material that is laminated at least from the outside in the order of a protective layer, a gas barrier layer, and a sealant layer, or in the order of a gas barrier layer, a protective layer, and a sealant layer, wherein the sealant layer is a porous material. And a thermal insulation exterior material comprising a resin composition comprising a thermoplastic resin, preferably the porous material has a specific surface area of 200 m 2 / g or more, and the content of the porous material is the mass of the resin composition Is 100% by mass, and the exterior material for vacuum heat insulating material is 0.25% by mass to 30% by mass. [Selection] Figure 2

Description

  The present invention relates to an exterior material for a vacuum heat insulating material that is attached to a cold insulation device such as a refrigerator, a low-temperature container, a heat insulation device, or an outer wall material of a residence.

  Vacuum heat insulating material wraps the core material (core material) with the exterior material, the surroundings of the core material is in a vacuum state, and the surrounding exterior material is heat-sealed and sealed, so that heat conduction by gas is reduced to zero. It is a heat insulating material that improves the heat insulating performance by approaching.

  The exterior material is required to have a gas barrier property in order to maintain the internal vacuum. Therefore, a laminated film using a metal foil such as an aluminum foil as a gas barrier layer is used as the exterior material. Alternatively, a laminated film using a metal vapor-deposited film obtained by vacuum-depositing a metal material or an inorganic vapor-deposited film obtained by vacuum-depositing an inorganic substance such as silicon oxide is used.

  Patent Documents 1 to 4 are all technical documents relating to the exterior material of such a vacuum heat insulating material. The exterior materials described in these patent documents 1 to 4 are laminated on a gas barrier layer, provided with a sealant layer (heat seal layer), and sealed by heat sealing the sealant layers to form a vacuum heat insulating material. (See FIG. 1). As the sealant layer, both polyethylene resin and polypropylene resin are used.

Japanese Patent Laid-Open No. 61-27392 JP 2003-262296 A JP 2006-21429 A JP 2010-138956 A

  However, since the vacuum heat insulating material is used in a refrigerator or a vending machine, the exterior material is heated for a long time, and outgas is generated from the sealant layer. As a result, there is a problem that the degree of vacuum decreases and heat conduction increases.

  The present invention has been made in view of the above problems, and by improving the sealant layer, it prevents a decrease in vacuum caused by outgas generated from the sealant layer by heating, and prevents deterioration (increase) in heat conduction. An object of the present invention is to provide an exterior material for a vacuum heat insulating material.

In order to solve the above problems, the invention according to claim 1 is a vacuum heat insulating material formed by laminating at least a protective layer, a gas barrier layer, and a sealant layer in this order from the outside, or a gas barrier layer, a protective layer, and a sealant layer in that order. For exterior materials,
The sealant layer is a vacuum heat insulating material exterior material comprising a resin composition composed of a porous material and a thermoplastic resin.

  According to a second aspect of the present invention, the sealant layer has a three-layer structure in which an intermediate layer is sandwiched between support layers, the support layer does not include a porous material, and the intermediate layer includes a porous material and a thermoplastic resin. It is a resin composition which consists of this, It is set as the exterior material for vacuum heat insulating materials of Claim 1 characterized by the above-mentioned.

As for invention of Claim 3, the specific surface area of the said porous substance is 200 m < ² > / g or more,
The content of the porous material is from 0.25% by mass to 30% by mass, based on 100% by mass of the resin composition, for a vacuum heat insulating material according to claim 1 or 2 It is an exterior material.

  The invention according to claim 4 is characterized in that the gas barrier layer comprises one or more layers selected from any one of a metal foil, a resin film deposited with a metal or an inorganic oxide. The exterior material for a vacuum heat insulating material according to any one of the above items.

  According to the vacuum insulating material exterior material of the present invention, since the sealant layer contains a porous material, the porous material is released before the outgas generated from the sealant layer due to long-term heating of the vacuum heat insulating material is released to the outside. Since it is adsorbed by the material, the vacuum degree of the vacuum heat insulating material can be prevented from being lowered. Therefore, a vacuum heat insulating material in which deterioration (rise) of heat conduction is suppressed can be obtained.

It is a schematic cross section which shows the structure of the vacuum heat insulating material provided with the exterior material for vacuum heat insulating materials. It is sectional drawing which shows the layer structure of the exterior material for vacuum heat insulating materials which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the layer structure of the exterior material for vacuum heat insulating materials which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the layer structure of the exterior material for vacuum heat insulating materials which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the layer structure of the exterior material for vacuum heat insulating materials which concerns on 4th Embodiment of this invention.

  Hereinafter, an embodiment of an exterior material for a vacuum heat insulating material according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same component unless there is a reason for convenience, and the overlapping description is abbreviate | omitted. Also, in the drawings used in the following description, the characteristic portions are enlarged for easy understanding of the features, and the dimensional ratios of the respective components are not the same as the actual ones.

(Structure of vacuum insulation)
FIG. 1 is a schematic cross-sectional view showing the structure of a vacuum heat insulating material 70 provided with a general vacuum heat insulating material exterior material. The vacuum heat insulating material using the vacuum heat insulating material of the present invention is a general vacuum heat insulating material except for the layer structure of the external materials 10, 20, 30, and 40 shown in FIGS. 70. The heat seal portion 35 is heat sealed by heat welding of the sealant layers.

(Configuration of exterior material for vacuum insulation)
FIG. 2 is a cross-sectional view showing the layer configuration of the vacuum heat insulating packaging material 10 according to the first embodiment of the present invention, taken along the line AA ′ of the vacuum heat insulating material 70 of FIG. 1. The vacuum heat insulating material exterior material 10 has a configuration in which a protective layer 1, a gas barrier layer 2, and a sealant layer 4 are laminated in order from the outside via an adhesive layer 7. Here, the sealant layer 4 includes a resin composition made of a porous material and a thermoplastic resin.

  FIG. 3 is a cross-sectional view similarly showing the layer configuration of the vacuum heat insulating exterior material 20 according to the second embodiment of the present invention in the A-A ′ cross section of FIG. 1. The exterior material 20 for vacuum heat insulating material of the second embodiment has a configuration in which a protective layer 1, a gas barrier layer 2, and a sealant layer 4 are laminated in order from the outside via an adhesive layer 7, respectively. The intermediate layer 5 has a three-layer structure in which the support layer 6 is sandwiched. Here, the support layer does not contain a porous material, and the intermediate layer is a resin composition comprising a porous material and a thermoplastic resin.

  FIG. 4 is a cross-sectional view similarly showing a layer configuration of the vacuum heat insulating packaging material 30 according to the third embodiment of the present invention in the A-A ′ cross section of FIG. 1. Unlike the configuration of the vacuum insulation material exterior material 10 of the first embodiment of FIG. 2, the vacuum insulation material exterior material 30 of the third embodiment has a gas barrier layer configuration, and the gas barrier layer 2 and the gas barrier layer 3 are The adhesive layer 7 adheres.

  FIG. 5 is a cross-sectional view showing the layer structure of the vacuum heat insulating packaging 40 according to the fourth embodiment of the present invention, similarly in the A-A ′ cross section of FIG. 1. Unlike the configuration of the vacuum insulation material exterior material 20 of the second embodiment of FIG. 3, the vacuum insulation material exterior material 40 of the fourth embodiment has a gas barrier layer configuration, and the gas barrier layer 2 and the gas barrier layer 3 are The adhesive layer 7 adheres.

  As described above, the vacuum insulating materials 10 and 30 of the first and third embodiments of the present invention include the resin composition in which the sealant layer 4 is made of a porous material and a thermoplastic resin. In addition, in the vacuum heat insulating packaging materials 20 and 40 of the second and fourth embodiments of the present invention, the support layer does not contain a porous material, and the intermediate layer is a resin composition made of a porous material and a thermoplastic resin. is there. Therefore, in the vacuum insulating material exterior material of the present invention, the porous material contained in the sealant layer 4 (first and third embodiments) before the outgas generated from the sealant layer 4 is released to the outside, or the intermediate Since it is adsorbed by the porous material contained in the layer 5 (second and fourth embodiments), the decrease in the degree of vacuum is suppressed and the increase in heat conduction is suppressed.

  Usually, when an additive is added to the sealant layer, the seal strength and tensile strength are lowered, and a seal failure is likely to occur. Therefore, as in the second and fourth embodiments, it is possible to suppress a decrease in seal strength by inserting a porous material only in the intermediate layer as necessary. In the case of a three-layer structure, the range of film thickness is preferably 10 to 50 μm for any layer, and more preferably the three layers have a structure of 15/15 to 25/15 μm.

In any of the embodiments, the specific surface area of the porous material of the present invention is preferably 200 m ² / g or more, and if it is smaller than this, the outgas adsorption amount becomes insufficient. Here, the specific surface area is a surface area per unit mass of the object. The content of the porous material is preferably in the range of 0.25% by mass to 30% by mass, where the mass of the resin composition is 100% by mass. If it is less than 0.25% by mass, the outgas adsorption amount is insufficient, and if it exceeds 30% by mass, the film strength becomes weak.

(Constituent material of the sealant layer 4)
Examples of the porous material include synthetic zeolite, calcium oxide, a silica compound having a hydroxyl group, a metal, and the like on the surface, an aluminum compound, a magnesium compound, and the like. Preferably, an aluminum compound or a magnesium compound having a hydroxyl group or a metal on the surface is used.

  The following are mentioned as a candidate of the thermoplastic resin containing a porous substance. Polyethylene resin such as polyethylene, ethylene-α olefin copolymer, poly α olefin composed of at least one α olefin, α olefin-ethylene copolymer, ethylene-cyclic olefin copolymer, ethylene-α, β unsaturated carboxylic Graft-modified polyolefin resin such as acid or esterified product thereof, ionic cross-linked product thereof, ethylene-vinyl acetate copolymer or partially saponified product or partially saponified product thereof, or acid anhydride, polystyrene Further, it may contain a thermoplastic resin which is a simple substance such as polyacrylonitrile or a mixture of one or more of these.

A thermoplastic resin having a melting point of 80 to 300 ° C. can be used for the sealant layer 4. However, since the core material is vacuum packaged, a material that does not generate outgas under vacuum is preferable. For this reason, a slip agent and a thermoplastic resin with a low low molecular weight component are desirable. When a slip agent is blended, the blend amount of the slip agent is preferably in the range of 500 to 4000 ppm. Examples of such a thermoplastic resin include polyolefin resins such as low density polyethylene, medium density polyethylene, linear low density polyethylene, and polypropylene. It is also possible to use a fluorine-based resin. When a slip agent is not included, it is preferable to include an anti-blocking agent (AB agent) as a countermeasure against slip.

  The support layer that sandwiches the intermediate layer in the second and fourth embodiments is preferably the same type of thermoplastic resin as the thermoplastic resin containing the porous material.

(Constituent material of gas barrier layer)
The gas barrier layer preferably includes at least one layer selected from a metal foil and a resin film deposited with a metal or an inorganic oxide, and is composed of alumina (aluminum oxide) or silica (silicon dioxide or silicon dioxide). It is preferable to have one or more layers selected from a resin film on which a substance to be deposited is deposited and to have transparency.

  Although the resin film used as the vapor deposition base of the gas barrier layer may be any material, a polyethylene terephthalate (PET) film arbitrarily stretched in the biaxial direction is preferably used from the viewpoint of heat resistance. In addition, an ethylene-vinyl alcohol copolymer (EVOH) film can be preferably used. An advantage of the EVOH film is that cracks are less likely to occur when an exterior material is molded. In particular, when two or more gas barrier layers are provided, by using a metal-deposited EVOH film on which a metal such as aluminum is vapor-deposited and a resin film on which an inorganic oxide such as aluminum or silica is vapor-deposited, It can be set as the exterior material for vacuum heat insulating materials excellent in barrier property.

(Method for manufacturing vacuum insulation)
Various methods can be used for laminating the gas barrier layer and the sealant layer. Typical examples include a method of laminating by a dry lamination method using a urethane-based adhesive, and a sealant layer containing a porous material formed in-line using a urethane-based adhesive for the gas barrier layer. Lamination method or knee laminating method, in-line urethane layer adhesive provided on gas barrier layer, porous material sealant layer formed by extrusion lamination with polyolefin resin, etc., sand lamination method And a method of laminating a cast or blown film of a polyolefin resin on the gas barrier layer by a dry lamination method in advance.

  In the second and fourth embodiments, as a method for producing a sealant layer having a three-layer structure of support layer / intermediate layer / support layer, various predetermined blending amounts of materials are used using a ribbon mixer, a tumbler mixer, a Henschel mixer, or the like. Dry blended or blended in a predetermined amount using each feeder pre-installed in a kneader, using a kneader such as a single screw extruder, twin screw extruder, or a Banbury mixer It is obtained by kneading.

  Hereinafter, the protective layer 1, the adhesive layer 7 and the other constituent elements of the vacuum heat insulating materials 10, 20, 30, 40 according to the first, second, third, and fourth embodiments of the present invention will be described. The gas barrier coating layer will be described as a gas barrier layer candidate other than the gas barrier layer.

(Protective layer 1)
The protective layer 1 enhances the strength when laminated and molding the exterior body and the puncture resistance after molding. As a material for the protective layer, stretched nylon is preferable from the viewpoint of mechanical strength (toughness). Examples of nylon include nylon 6, nylon 66, and a copolymer of nylon 66 and nylon 6 having a polyamide resin as a basic skeleton. A plurality of protective layers may be provided depending on the required quality. The protective layer may be disposed on the outermost layer on the side opposite to the sealant layer, or may be between the barrier layer and the sealant layer. Further, when a plurality of barrier layers are provided, they may be arranged between the barrier layers. A plurality of them may be provided. That is, a laminated structure of gas barrier layer / protective layer / gas barrier layer / sealant layer or protective layer / gas barrier layer / protective layer / gas barrier layer / sealant layer may be employed.

(Adhesive layer 7)
As the adhesive for the adhesive layer 7, an adhesive suitable for dry lamination and having low hygroscopicity is preferable. A two-component curable polyester adhesive is most preferable, but is not limited thereto. A two-component curable polyurethane adhesive, an acrylic adhesive, an epoxy adhesive, or the like may be used.

(Gas barrier coating layer)
When a resin film on which an inorganic oxide is deposited is used as the barrier layer, the gas barrier coating layer can improve bending resistance and barrier properties by being provided on the inorganic oxide. The gas barrier coating layer may include a water-soluble polymer and an inorganic compound. Examples of the water-soluble polymer include polyvinyl alcohol (PVA), polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when PVA is used, the gas barrier property is excellent, which is preferable.

The inorganic compound that forms the gas barrier coating layer is preferably obtained by hydrolyzing one or more metal alkoxides. The metal alkoxide is a compound represented by a general formula: M (OR) _n (M: metal such as Si, Ti, Al, Zr, O: oxygen, alkyl group such as R: CH ₃ , C ₂ H ₅ ). For example, tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] and triisopropoxy aluminum [Al (O-iso-C ₃ H ₇ ) ₃ ] are relatively stable in an aqueous solvent after hydrolysis. Preferably used.

  The gas barrier coating layer is prepared by mixing a water-soluble polymer dissolved in water or a water / alcohol mixed solvent with a metal alkoxide that has been treated directly or previously hydrolyzed, and this mixed solution is transparent. What was formed by heating and drying after coating on the conductive vapor deposition layer 2 is preferable.

  It is also possible to add known additives such as isocyanate compounds, silane coupling agents, or dispersants, stabilizers, viscosity modifiers, colorants and the like to the mixed solution as long as the gas barrier properties are not impaired. It is.

  When PVA is used as the water-soluble polymer, the proportion of PVA in the mixed solution is desirably 20 wt% (mass%) or more and 50 wt% or less, more preferably 25 to 40 wt% of the total solid content of the mixed solution. Range. If the PVA is less than 20 wt%, the flexibility of the film is impaired, and it becomes difficult to form a gas barrier coating layer. Moreover, when more than 50 wt%, since sufficient gas barrier property cannot be provided, it is unpreferable.

  By adding a silane coupling agent to the mixed solution for forming the gas barrier coating layer, the water resistance of the gas barrier coating layer can be improved, and the gas barrier layer 4 is resistant to heat sterilization or gas barrier under high temperature and high humidity. It is possible to better prevent the deterioration of the property. When the organic functional group of the silane coupling agent is selected from those having a vinyl group, an epoxy group, a methacryloxy group, a ureido group, or an isocyanate group, the water resistance is further improved because the functional group is hydrophobic.

  When converted to a weight ratio after hydrolysis, the silane coupling agent is 12 wt% or less of the total solid content in the mixed solution, and the total of PVA and the silane coupling agent is 20 wt% or more and 50 wt% or less of the total solid content. It is desirable that When the amount of the silane coupling agent is large, the function as a gas barrier coating layer cannot be obtained, which is not preferable.

  Hereinafter, the vacuum insulating material exterior material of the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples without departing from the gist of the present invention. .

(Method for producing sealant layer of Examples 1 and 2)
Using a three-kind three-layer coextrusion laminating machine, a two-kind three-layer co-extruded three-layer film in which an intermediate layer composed of a resin composition layer containing a porous material is sandwiched between both sides by the same support layer is formed. Layered. The film thickness is 15 μm / 20 μm / 15 μm from the outside. The materials used for the intermediate layer and the support layer were dry blended. The same resin as that for the intermediate layer was used for the support layer. Further, at least one of the sealant layers was subjected to corona treatment.

<Example 1>
A stretched nylon film having a thickness of 15 μm was used as the protective layer 1, an alumina-deposited PET film having a thickness of 12 μm was used as the gas barrier layer 2, and an aluminum-deposited EVOH copolymer film having a thickness of 15 μm was used as the gas barrier layer 3. As the sealant layer 4, 15% by mass of synthetic zeolite (PEX CLT-73AL / manufactured by Tokyo Ink) is used as the porous material for the intermediate layer 5, and 85% by mass of low density polyethylene (density 0.918, MFR7) is used as the thermoplastic resin. The support layer 6 was made of low density polyethylene (density 0.918, MFR7), which is a thermoplastic resin. These protective layer 1, gas barrier layer 2, gas barrier layer 3, and sealant layer 4 are laminated and bonded in this order as a bonding layer 7 by a dry lamination method via a two-component curable urethane adhesive, and the book shown in FIG. A vacuum insulation material 40 according to the fourth embodiment of the invention was produced. This exterior material was filled with glass wool as a core material to produce a vacuum heat insulating material 70 of Example 1 shown in FIG.

<Example 2>
As the sealant layer 4, 15% by mass of a compound having a hydroxyl group as a porous substance (KYOWARD 200S / Kyowa Chemical Industry) and 85% by mass of low-density polyethylene (density 0.918, MFR7) as a thermoplastic resin are used as the sealant layer 4. The vacuum heat insulating material according to the fourth embodiment of the present invention was used in the same material and method as in Example 1 except that the support layer 6 was low-density polyethylene (density 0.918, MFR7), which is a thermoplastic resin. The exterior packaging material 40 was produced and the vacuum heat insulating material 70 of Example 2 was produced.

<Example 3>
As the sealant layer 4, 15% by mass of synthetic zeolite (PEX CLT-73AL / manufactured by Tokyo Ink) is used for the porous material layer, and 85% by mass of low-density polyethylene (density 0.918, MFR7) is used for the thermoplastic resin. Example 3 is the same material and method as Example 1 except that a single layer film (50 μm thick) is used and the vacuum heat insulating packaging material 30 of the third embodiment of the present invention shown in FIG. The vacuum heat insulating material 70 was produced.

<Comparative Example 1>
The same material and method as in Example 1 except that the sealant layer 4 is a low-density polyethylene (density 0.918, MFR7) 100% by mass single layer film that does not contain a porous material, and a vacuum heat insulating material is produced. The vacuum heat insulating material 70 of the comparative example 1 was produced.

[Evaluation]
<Measurement of thermal conductivity>
The thermal conductivity immediately after production of the vacuum heat insulating materials of Examples 1 to 3 and Comparative Example 1 produced with a 180 mm square size and a four-side seal was measured and the thermal conductivity after storage for 90 ° C./2 months was measured. The apparatus used was a thermal conductivity measuring instrument (apparatus: FOX200, TA Instruments Japan Co., Ltd.). In addition, it was set as the measured value in 22.5 degreeC.

<Seal strength>
The center part of each side of the vacuum heat insulating materials of Examples 1 to 3 and Comparative Example 1 sealed in four directions was cut with a width of 15 mm, and the seal strength at a speed of 300 mm / min was measured (conforms to JIS Z1707). As the apparatus, a Tensilon universal material testing machine (apparatus: RTF-1250, manufactured by A & I) was used.

  Table 1 summarizes the conditions for the sealant layers of Examples 1, 2, 3 and Comparative Example 1 and the evaluation results of the vacuum heat insulating material.

  Since Examples 1, 2, and 3 all satisfy the conditions defined in the present invention, the increase in thermal conductivity after 90 ° C./2 months storage was small and good results were obtained. In Example 3, since the entire sealant layer contained the porous material, the seal strength was reduced, but was within an allowable range. On the other hand, since the comparative example 1 did not contain a porous material in the sealant layer, the increase in thermal conductivity was significantly poor.

DESCRIPTION OF SYMBOLS 1 ........ Protective layer 2, 3 ... Gas barrier layer 4 .... Sealant layer 5 .... Intermediate layer 6 .... Support layer 7... Adhesive layer 10, 20, 30, 40, 50... Vacuum insulation material exterior material 35... Heat seal part 60... Core material 70. .... Vacuum insulation

Claims (4)

It is a vacuum heat insulating exterior material laminated in the order of at least a protective layer, a gas barrier layer, a sealant layer, or a gas barrier layer, a protective layer, and a sealant layer in this order,
The exterior material for a vacuum heat insulating material, wherein the sealant layer includes a resin composition composed of a porous material and a thermoplastic resin. The sealant layer has a three-layer structure in which an intermediate layer is sandwiched between support layers,
The exterior material for a vacuum heat insulating material according to claim 1, wherein the support layer does not contain a porous material, and the intermediate layer is a resin composition comprising a porous material and a thermoplastic resin. The specific surface area of the porous material is 200 m ² / g or more,
The content of the porous material is from 0.25% by mass to 30% by mass, based on 100% by mass of the resin composition, for a vacuum heat insulating material according to claim 1 or 2 Exterior material.   The vacuum insulation according to any one of claims 1 to 3, wherein the gas barrier layer includes one or more layers selected from a metal foil and a resin film deposited with a metal or an inorganic oxide. Exterior material for materials.