JP2016117201A - Multilayer sheet and method for producing the same, outer covering material, and vacuum heat insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer sheet which has low thermal conductivity and high gas barrier properties, and is excellent in long-term reliability under high-temperature condition and a method for producing the same; an outer covering material provided with the multilayer sheet; and a vacuum heat insulation material provided with the outer covering material and a core material.SOLUTION: A multilayer sheet includes: a first film which contains a thermoplastic resin as a main component; a second film which is laminated on one surface side of the first film and contains a vinyl alcohol-based polymer as a main component; and an inorganic vapor deposition layer laminated on one surface of the second film. A ratio of storage elastic modulus at 100°C to storage elastic modulus at 25°C in the first film is 60% or more. An average thickness of the inorganic vapor deposition layers is 30 nm or more and 100 nm or less. Preferably, the first film has a resin layer which contains the thermoplastic resin as a main component, and a vapor deposition layer laminated on the resin layer. Preferably, the thermoplastic resin is polyester.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multilayer sheet, a method for producing the multilayer sheet, a jacket material provided with the multilayer sheet, and a vacuum heat insulating material provided with the jacket material.

  In recent years, a vacuum heat insulating material in which a multilayer sheet having heat insulating properties is disposed on an outer peripheral surface has been used as a heat insulating material for a refrigerator, a heat insulating panel for a house, a heat insulating material for a natural refrigerant heat pump water heater, or the like. In such a vacuum heat insulating material, in order to reduce gas heat transfer and improve heat insulation by maintaining the inside of the heat insulating material at a high degree of vacuum, the multilayer sheet is required to have high gas barrier properties.

  In order to satisfy this requirement, a multilayer sheet in which aluminum foil is laminated is used. However, the thermal conductivity of aluminum is about 200 W / m · K, which is larger than the thermal conductivity of polypropylene of about 0.23 W / m · K and the thermal conductivity of air of about 0.02 W / m · K. For this reason, the multilayer sheet laminated with aluminum foil generates a heat bridge in which heat travels along the aluminum foil portion, and the heat insulation performance of the vacuum heat insulating material is greatly reduced.

  Therefore, in order to achieve both a reduction in heat bridge and an improvement in gas barrier properties, a vacuum is provided with a multilayer sheet in which very thin inorganic vapor-deposited layers mainly composed of metals such as aluminum and metal oxides such as silica and alumina are laminated. Thermal insulators have been developed (see Patent Document 1, Patent Document 2 and Patent Document 3).

  However, in the said conventional vacuum heat insulating material, a multilayer sheet expand | swells on about 100 degreeC high temperature conditions, and a crack may arise in the said inorganic vapor deposition layer. In addition, the inorganic vapor-deposited layer may be eroded or altered by high-temperature water vapor. As a result, the gas barrier property of the multilayer sheet is lowered and the heat insulating property is lowered. For this reason, the conventional vacuum heat insulating material still has insufficient long-term reliability under high temperature conditions.

JP-A-10-122477 JP 2008-114520 A JP-A-2-310032

  The present invention has been made based on the above circumstances, and has a multilayer sheet having high gas barrier properties and excellent long-term reliability under high-temperature conditions, a method for producing the multilayer sheet, and a jacket having the multilayer sheet. It aims at providing a vacuum heat insulating material provided with a material and this jacket material.

  The invention made in order to solve the above-mentioned problems is a first film mainly composed of a thermoplastic resin, and a second film laminated on one surface side of the first film and mainly composed of a vinyl alcohol polymer. A multilayer sheet comprising a film and an inorganic vapor deposition layer laminated on one surface of the second film, wherein the ratio of the storage elastic modulus at 100 ° C. to the storage elastic modulus at 25 ° C. in the first film is 60%. It is above, It is a multilayer sheet characterized by the average thickness of the said inorganic vapor deposition layer being 30 nm or more and 100 nm or less.

  The multilayer sheet includes a first film and a second film laminated on one surface side of the first film, and the second film has a vinyl alcohol polymer as a main component, thereby providing heat insulation properties. Excellent. Moreover, the said multilayer sheet has a high gas barrier property by providing the inorganic vapor deposition layer laminated | stacked on one surface of this 2nd film. Furthermore, the said multilayer sheet can reduce the expansion | swelling in high temperature conditions because the ratio of the storage elastic modulus of the said 1st film is more than the said minimum. In addition, when the average thickness of the inorganic vapor deposition layer is within the above range, it is possible to reduce a deterioration in gas barrier properties due to deformation or erosion of the inorganic vapor deposition layer under high temperature conditions. As a result, the multilayer sheet is excellent in long-term reliability under high temperature conditions.

  Another invention made in order to solve the above-mentioned subject is a jacket material provided with the multilayer sheet concerned. By providing the multilayer sheet, the jacket material has high gas barrier properties and excellent long-term reliability under high temperature conditions.

  Still another invention made in order to solve the above-mentioned problems is a vacuum heat insulating material comprising a core material and the jacket material for vacuum-packaging the core material. The said vacuum heat insulating material has a high gas barrier property by providing the said jacket material, and is excellent in the long-term reliability in high temperature conditions.

  The present invention also includes a first film mainly composed of a thermoplastic resin, a second film laminated on one surface side of the first film and mainly composed of a vinyl alcohol polymer, and the second film. A method for producing a multilayer sheet comprising an inorganic vapor-deposited layer laminated on one surface of a film, wherein the ratio of the storage elastic modulus at 25 ° C to the storage elastic modulus at 100 ° C in the first film is 60% or more. A multilayer sheet comprising: a step of laminating a second film on one surface side of the first film; and a step of laminating an inorganic vapor deposition layer on one surface of the second film by vapor deposition of an inorganic substance. Including the manufacturing method. Thus, the said manufacturing method can manufacture the said multilayer sheet easily and reliably by providing the said process.

  Here, the “main component” is a component having the highest content (for example, a component contained in 90% by mass or more). The “storage modulus” is a value measured using a dynamic viscoelasticity measuring device based on JIS-K7244-4 (1999).

  As described above, the multilayer sheet, the jacket material, and the vacuum heat insulating material of the present invention have low thermal conductivity and high gas barrier properties, and are excellent in long-term reliability under high temperature conditions. Moreover, the manufacturing method of the multilayer sheet of this invention can manufacture the said multilayer sheet easily and reliably.

FIG. 1 is a schematic cross-sectional view of the multilayer sheet of the present invention.

<Multilayer sheet>
As shown in FIG. 1, the multilayer sheet is laminated on a first film 1 mainly composed of a thermoplastic resin and one surface side (back surface side) of the first film 1, and a vinyl alcohol polymer ( Hereinafter, the vinyl alcohol polymer may be abbreviated as “PVA”.) The second film 2 having as a main component, and the inorganic vapor deposition layer 3 laminated on one surface (back surface) of the second film 2. With. The multilayer sheet may further include a third film 4 laminated on one surface side (back surface side) of the inorganic vapor deposition layer 3. In addition, in this embodiment, the "surface side" refers to the side on which the first film 1 is laminated in the thickness direction of the multilayer sheet and the jacket material. It does not determine the front or back of the jacket material in use.

[First film]
The 1st film 1 has the resin layer 1a which has a thermoplastic resin as a main component. Moreover, the 1st film 1 is good to further have the vapor deposition layer 1b laminated | stacked on this resin layer 1a.

  Examples of the thermoplastic resin include polyolefin, polyester, polyamide, polystyrene, poly (meth) acrylic acid ester, polyacrylonitrile, polyvinyl acetate, polycarbonate, polyarylate, regenerated cellulose, polyimide, polyetherimide, polysulfone, and polyether. Examples include sulfone, polyether ether ketone, and ionomer resin.

  Examples of the polyolefin include polyethylene and polypropylene. Examples of the polyester include polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and copolymers thereof. Examples of the polyamide include nylon-6, nylon-66, nylon-12, and the like.

  Among these, polyethylene, polypropylene, polyethylene terephthalate, nylon-6 or nylon-66 are preferable as the thermoplastic resin.

  As an upper limit of the average thickness of the 1st film 1, 200 micrometers is preferable, 100 micrometers is more preferable, and 60 micrometers is further more preferable. On the other hand, the lower limit of the average thickness is preferably 1 μm, more preferably 5 μm, and even more preferably 7 μm. When the average thickness exceeds the upper limit, the thickness of the multilayer sheet may be excessively increased. Conversely, when the average thickness is less than the lower limit, the mechanical strength and workability of the first film 1 may be reduced.

  The upper limit of the storage elastic modulus at 25 ° C. of the first film 1 is preferably 10,000 MPa, and more preferably 8000 MPa. On the other hand, the lower limit of the storage elastic modulus is preferably 1000 MPa, and more preferably 2000 MPa.

  The upper limit of the storage elastic modulus at 100 ° C. of the first film 1 is preferably 10,000 MPa, and more preferably 8000 MPa. On the other hand, the lower limit of the storage elastic modulus is preferably 600 MPa and more preferably 1200 MPa.

  If the storage elastic modulus at 25 ° C. and 100 ° C. of the first film 1 exceeds the above upper limit, the workability of the first film 1 may be reduced. Conversely, when the storage elastic modulus is less than the lower limit, the strength of the first film 1 may be reduced. Here, the “storage modulus” is a value measured using a dynamic viscoelasticity measuring device in accordance with JIS-K7244-4 (1999).

  The lower limit of the ratio of the storage elastic modulus at 100 ° C. to the storage elastic modulus at 25 ° C. of the first film 1 is 60%, and preferably 62%. On the other hand, the upper limit of the ratio is preferably 90% and more preferably 85%. When the said ratio is less than the said minimum, there exists a possibility that reduction of the gas barrier property under high temperature conditions cannot fully be suppressed. Conversely, if the ratio exceeds the upper limit, the workability of the first film 1 may be reduced.

  As an upper limit of the 25 degreeC loss coefficient of the 1st film 1, 0.1 is preferable and 0.05 is more preferable. On the other hand, the lower limit of the loss factor is preferably 0.001 and more preferably 0.005.

  The upper limit of the loss coefficient at 100 ° C. of the first film 1 is preferably 0.15, and more preferably 0.1. On the other hand, the lower limit of the loss factor is preferably 0.01, and more preferably 0.03.

  If the loss factor exceeds the upper limit, the reduction in gas barrier properties under high temperature conditions may not be sufficiently suppressed. Conversely, when the loss factor is less than the lower limit, the workability of the first film 1 may be reduced. Here, the “loss factor” is a value measured using a dynamic viscoelasticity measuring device in accordance with JIS-K7244-4 (1999).

  The resin layer 1a of the first film 1 may be a stretched film or an unstretched film, but a stretched film is preferable and a biaxially stretched film is more preferable from the viewpoint of improving processability such as printing and lamination of the multilayer sheet. preferable. Examples of the method for producing the biaxially stretched film include a simultaneous biaxial stretch method, a sequential biaxial stretch method, and a tubular stretch method.

  As a main component of the said vapor deposition layer 1b, a metal, a metal oxide, or a nonmetal is mentioned, for example. As this metal etc., the thing similar to the inorganic vapor deposition layer 3 mentioned later is mentioned, for example, Among these, aluminum is preferable. The vapor deposition layer 1b can be laminated | stacked by vapor-depositing the said metal etc. on the back surface of the resin layer 1a.

  As an upper limit of the average thickness of the vapor deposition layer 1b, 200 nm is preferable, 180 nm is more preferable, 150 nm is further more preferable. On the other hand, the lower limit of the average thickness is preferably 20 nm, and more preferably 30 nm. If the average thickness exceeds the upper limit, cracks or the like may be easily generated. Conversely, if the average thickness is less than the lower limit, the gas barrier properties of the first film 1 may be difficult to improve.

[Second film]
The 2nd film 2 is laminated | stacked on the back surface side of the said 1st film 1, and has a vinyl alcohol polymer as a main component.

PVA is not particularly limited as long as it contains the vinyl alcohol units obtained by saponifying a vinyl ester unit _(-CH 2 -CHOH-), such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer (hereinafter, the EVOH May be abbreviated.). Examples of the polyvinyl alcohol include unmodified polyvinyl alcohol and modified polyvinyl alcohol. PVA may be used alone or in combination of two or more.

  The unmodified polyvinyl alcohol can be produced, for example, by saponifying a vinyl acetate homopolymer. The modified polyvinyl alcohol can be produced, for example, by saponifying vinyl acetate and an unsaturated monomer copolymerizable with vinyl acetate. Further, it may be modified after polymerizing vinyl acetate alone. The modified amount in the modified polyvinyl alcohol is usually less than 10 mol%.

  Examples of unsaturated monomers copolymerizable with vinyl acetate include olefins, hydroxy group-containing α-olefins, derivatives such as acylated products thereof, unsaturated acids and salts thereof, monoesters, dialkyl esters, nitrile compounds, amides. Examples thereof include compounds, olefin sulfonic acids and salts thereof, vinyl compounds, substituted vinyl acetates, vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate.

  Examples of the method of modifying the vinyl acetate after polymerizing alone include a method of converting polyvinyl alcohol into acetoacetate ester, acetalization, urethanization, etherification, grafting, phosphate esterification or oxyalkylene.

  As an upper limit of the polymerization degree of polyvinyl alcohol, 4000 is preferable and 2600 is more preferable. On the other hand, as a minimum of the said polymerization degree, 1100 is preferable and 1200 is more preferable. When the polymerization degree exceeds the upper limit, the workability at the time of forming the second film 2 and stretching may be lowered. Conversely, when the degree of polymerization is less than the lower limit, the mechanical strength of the second film 2 may be reduced.

  As an upper limit of the saponification degree of polyvinyl alcohol, 100 mol% is preferable and 99.99 mol% is more preferable. On the other hand, the lower limit of the saponification degree is preferably 90 mol%, more preferably 95 mol%, and even more preferably 99 mol%. When the saponification degree is less than the above lower limit, the water resistance of the second film 2 may be lowered.

  The EVOH is usually obtained by saponifying a copolymer of 10 to 60 mol% ethylene and vinyl ester. Examples of the vinyl ester include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, and vinyl pivalate.

  EVOH may contain a vinyl silane compound as a copolymerization component. Thus, EVOH contains a vinyl silane compound, and the stability at the time of heat-melting improves. Examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxyethoxy) silane, and γ-methacryloxypropylmethoxysilane, with vinyltrimethoxysilane or vinyltriethoxysilane being preferred. . As content of the said vinylsilane compound, 0.0002 mol% or more and 0.2 mol% or less are preferable.

  Furthermore, EVOH may contain other copolymerizable monomers as long as the object of the present invention is not inhibited. Examples of such copolymerizable monomers include propylene, butylene; unsaturated carboxylic acids such as (meth) acrylic acid, methyl (meth) acrylate, and ethyl (meth) acrylate; or esters thereof; N-vinylpyrrolidone And vinyl pyrrolidone such as

  As an upper limit of the ethylene content of EVOH, 60 mol% is preferable, 55 mol% is more preferable, and 50 mol% is further more preferable. On the other hand, the lower limit of the ethylene content is preferably 10 mol%, more preferably 15 mol%, and even more preferably 20 mol%. If the ethylene content exceeds the upper limit, the gas barrier properties of the second film 2 may be reduced. Conversely, when the ethylene content is less than the lower limit, the melt moldability of the second film 2 may be reduced. Here, the ethylene content of EVOH is a value determined by a nuclear magnetic resonance (NMR) method.

  As an upper limit of the saponification degree of EVOH, 100 mol% is preferable and 99.99 mol% is more preferable. On the other hand, the lower limit of the saponification degree is preferably 90 mol%, more preferably 95 mol%, and even more preferably 99 mol%. When the said saponification degree is less than the said minimum, there exists a tendency for the gas barrier property of the 2nd film 2 under high humidity to fall.

  EVOH may contain additives such as acids and metal salts from the viewpoint of thermal stability and viscosity adjustment. Examples of the additive include alkali metal salts, carboxylic acids and / or salts thereof, phosphoric acid compounds, and boron compounds.

  The upper limit of the average thickness of the second film 2 is preferably 100 μm, more preferably 50 μm, and still more preferably 40 μm. On the other hand, the lower limit of the average thickness is preferably 5 μm, more preferably 8 μm, and even more preferably 10 μm. When the average thickness exceeds the upper limit, the thickness of the multilayer sheet may be excessively increased. Conversely, when the average thickness is less than the lower limit, the mechanical strength and workability of the second film 2 may be reduced.

  Examples of the second film 2 include an unstretched film, a uniaxially stretched film, a biaxially stretched film, and the like. From the viewpoint of improving the gas barrier property of the second film 2, a uniaxially stretched film or a biaxially stretched film is preferable. Is more preferable. The stretching ratio in the flow direction (MD direction) of the uniaxially stretched film and the biaxially stretched film is preferably 2.5 times or more and 5 times or less. Examples of such a stretching method include a uniaxial stretching method, a simultaneous biaxial stretching method, and a sequential biaxial stretching method.

  The method for forming the second film 2 is not particularly limited. For example, a casting method in which a PVA solution is cast on a metal surface such as a drum or an endless belt to form a film, or melt molding in which an extruder is used for melt extrusion. Law.

[Inorganic vapor deposition layer]
The inorganic vapor deposition layer 3 is laminated on the back side of the second film 2. Moreover, as the inorganic vapor deposition layer 3, what has the barrier property with respect to oxygen gas or water vapor | steam is preferable.

  Examples of the main component of the inorganic vapor deposition layer 3 include metals such as aluminum, inorganic oxides, inorganic nitrides, inorganic carbides such as silicon carbide, and mixtures thereof. Examples of the inorganic oxide include aluminum oxide, silicon oxide, silicon oxynitride, magnesium oxide, and tin oxide. Examples of the inorganic nitride include silicon nitride and silicon carbonitride. The main component of the inorganic vapor deposition layer 3 is preferably aluminum, aluminum oxide, silicon oxide, magnesium oxide or silicon nitride from the viewpoint of excellent barrier properties against oxygen gas and water vapor.

  The lower limit of the average thickness of the inorganic vapor deposition layer 3 is 30 nm, preferably 40 nm, and more preferably 45 nm. On the other hand, the upper limit of the average thickness is 100 nm, preferably 90 nm, and more preferably 70 nm. When the said average thickness is less than the said minimum, there exists a possibility that the barrier property of the inorganic vapor deposition layer 3 may fall. On the contrary, when the average thickness exceeds the upper limit, the barrier property of the inorganic vapor deposition layer 3 may be easily lowered when the multilayer sheet is deformed.

  As a minimum of adhesion strength of the 2nd film 2 and inorganic vapor deposition layer 3, 0.98N / 15mm is preferred, 1.0N / 15mm is more preferred, and 1.1N / 15mm is still more preferred. On the other hand, the upper limit of the adhesion strength is preferably 3.0 N / 15 mm, and more preferably 2.5 N / mm. When the said adhesion strength is less than the said minimum, when the said multilayer sheet is deformed, there exists a possibility that the inorganic vapor deposition layer 3 may become easy to peel from the 2nd film 2. FIG. On the contrary, if the adhesion strength exceeds the upper limit, the inorganic vapor deposition layer 3 may be easily damaged in a vacuum heat insulating material or the like provided with the multilayer sheet. Here, “adhesion strength between the second film 2 and the inorganic vapor-deposited layer 3” means a T-type peel strength measuring device (“Autograph AGS-H” manufactured by Shimadzu Corporation), a peel rate of 250 mm / min, and a temperature of 23. It is the adhesive force per 15 mm width measured under the conditions of ° C. and humidity 50% RH.

[Third film]
The 3rd film 4 is laminated | stacked on the back surface side of the inorganic vapor deposition layer 3, and has the resin layer 4a which has a thermoplastic resin as a main component, and the vapor deposition layer 4b laminated | stacked on this resin layer. As the main component of the thermoplastic resin and the vapor deposition layer 4b, for example, the same materials as those mentioned in the first film 1 can be used. The average thickness of the third film 4 can be the same as that of the first film 1.

100 ° C. of the multilayer sheet, the upper limit of the oxygen permeability at 0% RH, preferably ^{1.6mL / (m 2 · day ·} atm), 1.5mL / (m 2 · day · atm) is more preferable. On the other hand, the lower limit of the oxygen permeation amount is preferably 0.1 mL / (m ² · day · atm), more preferably 0.3 mL / (m ² · day · atm). When the oxygen permeation amount exceeds the upper limit, the gas barrier property of the multilayer sheet may be lowered. Conversely, when the oxygen transmission amount is less than the lower limit, the production cost of the multilayer sheet may increase.

[Multilayer sheet manufacturing method]
The method for producing the multilayer sheet includes a step of laminating the second film 2 on one surface side (back surface side) of the first film 1 (hereinafter sometimes abbreviated as “film laminating step”), and an inorganic substance. The process of forming the inorganic vapor deposition layer 3 in one side (back surface) of the 2nd film 2 by vapor deposition of (it may abbreviate as "vapor deposition process" hereafter) is provided.

(Film lamination process)
In this step, the second film 2 is laminated on the back side of the first film 1. As this lamination method, for example, a method of applying a coating liquid mainly composed of PVA on the back side of the first film 1 to form a coating film, and then drying the coating film, a method of applying heat to the surface side of the second film 2 is used. A method of forming a coating film by applying a coating liquid containing a plastic resin as a main component and then drying the coating film; a method of bonding the first film 1 and the second film 2 together with an adhesive; Examples thereof include a method in which the film 1 and the second film 2 are manufactured and then bonded together by hot pressing, a method in which the first film 1 and the second film 2 are coextruded, and the like.

(Deposition process)
In this step, the inorganic vapor deposition layer 3 is formed on the back side of the second film 2. Specifically, the metal etc. which were illustrated as a main component of the said inorganic vapor deposition layer 3 are vapor-deposited etc. on the back surface side of the 2nd film 2. FIG.

  Examples of the method for forming the inorganic vapor deposition layer 3 include vacuum vapor deposition, sputtering, ion plating, and chemical vapor deposition (CVD). Among these, the vacuum deposition method is preferable from the viewpoint of productivity. In addition, examples of the heating method in the vacuum deposition method include an electron beam heating method, a resistance heating method, an induction heating method, and the like. In order to improve the adhesion strength between the inorganic vapor deposition layer 3 and the second film 2, a plasma assist method or an ion beam assist method may be used. Furthermore, in order to increase the transparency of the inorganic vapor deposition layer 3, a reactive vapor deposition method in which an oxygen gas or the like is reacted during vapor deposition may be employed.

  Although a vapor deposition process may be performed before a lamination process and may be performed after a lamination process, the viewpoint of reducing the thermal deterioration of the multilayer sheet by inorganic vapor deposition, and the adhesive strength of the inorganic vapor deposition layer 3 and the 2nd film 2 From the viewpoint of improving the thickness, it is preferably performed after the lamination step.

<Coating material>
The jacket material includes the multilayer sheet. The jacket material may be composed of only the multilayer sheet, but may further include other layers. Thus, when the said jacket material is provided with another layer, heat sealing property can be provided to the said jacket material, and the barrier property and mechanical property of the said jacket material can be improved more. In addition, the jacket material may further include an anchor coat layer or an adhesive layer that adheres the other layers to the multilayer sheet.

  Examples of the other layers include a thermoplastic resin layer, a thermosetting resin layer, a fiber layer such as fabric and paper, a wood layer, a glass layer, and a metal layer. Among these, a thermoplastic resin layer is preferable, a polyolefin layer, a polyester layer, a polyamide layer, and a vinyl alcohol polymer layer are more preferable, and a polypropylene layer, a polyethylene layer, a polyethylene terephthalate layer, and an EVOH layer are further preferable. When the other layers are these layers, heat sealing properties can be imparted to the jacket layer, and the mechanical properties of the jacket material can be further improved.

<Vacuum insulation>
The said vacuum heat insulating material is provided with the core material and the said jacket material which vacuum-packs this core material. Moreover, you may further provide the contact bonding layer which adhere | attaches a core material and the said jacket material.

[Core]
The main component of the core material is not particularly limited as long as it has heat insulation properties. For example, pearlite powder, silica powder, precipitated silica powder, diatomaceous earth, calcium silicate, glass fiber, rock wool, styrene foam and urethane foam. Examples thereof include foamed resins. Examples of the shape of the core material include a film shape, a hollow container shape, and a honeycomb shape. Moreover, you may include the getter material which adsorb | sucks water vapor | steam, gas, etc. in a core material as needed.

  In the said vacuum heat insulating material, since the jacket material vacuum-wraps a core material, the internal space between a core material and a jacket material is a vacuum state. The vacuum state here does not necessarily mean an absolute vacuum state, but means that the pressure in the internal space is sufficiently lower than the atmospheric pressure. The upper limit of the pressure in the internal space is preferably 2 kPa, more preferably 200 Pa, and even more preferably 20 Pa. On the other hand, the lower limit of the pressure in the internal space is preferably 0.001 Pa. When the said pressure exceeds the said upper limit, there exists a possibility that the heat insulation of the said vacuum heat insulating material may fall. Conversely, when the pressure is less than the lower limit, the manufacturing cost of the vacuum heat insulating material may increase.

  The upper limit of the thermal conductivity immediately after the production of the vacuum heat insulating material is preferably 3 mW / mK, more preferably 2.5 mW / mK. On the other hand, the lower limit of the thermal conductivity immediately after the production is preferably 1 mW / mK, and more preferably 1.2 mW / mK. When the thermal conductivity exceeds the upper limit, the heat insulating performance of the vacuum heat insulating material may be insufficient. Conversely, if the thermal conductivity is less than the lower limit, the manufacturing cost of the vacuum heat insulating material may increase. Here, the “thermal conductivity” is a value measured according to JIS-A1412-1 (1999).

  The upper limit of the thermal conductivity after the vacuum heat insulating material is stored for 50 days at 100 ° C. is preferably 19 mW / mK, and more preferably 18 mW / mK. On the other hand, the lower limit of the thermal conductivity after storing the vacuum heat insulating material at 100 ° C. for 50 days is preferably 3 mW / mK, and more preferably 5 mW / mK. When the thermal conductivity exceeds the upper limit, the vacuum heat insulating material may not be suitable for use in a high temperature environment. Conversely, if the thermal conductivity is less than the lower limit, the manufacturing cost of the vacuum heat insulating material may increase.

  The upper limit of the thermal conductivity after storing the vacuum heat insulating material at 100 ° C. for 50 days is preferably 10 times, more preferably 9.5 times the thermal conductivity before storage. On the other hand, the lower limit of the thermal conductivity after storing the vacuum heat insulating material at 100 ° C. for 50 days is preferably 1.5 times and more preferably 2 times the thermal conductivity before storage. When the thermal conductivity exceeds the upper limit, the vacuum heat insulating material may not be suitable for use in a high temperature environment. Conversely, if the thermal conductivity is less than the lower limit, the manufacturing cost of the vacuum heat insulating material may increase.

[Method of manufacturing vacuum insulation]
As a method for manufacturing the vacuum heat insulating material, for example, the core material is sandwiched between two outer cover materials, or the process of bending one outer cover material and sandwiching the core material inside thereof, Examples include a step of heat-sealing the portion other than the portion serving as the exhaust port in the outer peripheral portion, and a sealing step in which the internal space of the heat insulating material is evacuated by the exhaust port and the exhaust port is heat-sealed and closed in that state. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited at all by this. In addition, in an Example, the "surface" of a laminated body provided with a 2nd film and an inorganic vapor deposition layer means the surface by the side of a 2nd film, and a "back surface" means the surface by the side of an inorganic vapor deposition layer.

<Manufacture of multilayer sheets>
[First film]
The following film was used as the first film.
A-1: Stretched polyethylene terephthalate film having an average thickness of 12 μm (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.)
A-2: Aluminum vapor-deposited stretched polyethylene terephthalate film having an average thickness of 12 μm (“VM-PET 1510” from Toray Film Processing Co., Ltd., average thickness of aluminum vapor-deposited layer 50 nm)
A-3: Aluminum vapor-deposited stretched polyethylene terephthalate film in which an aluminum vapor-deposited layer was formed so that the average thickness of the vapor-deposited layer was 100 nm on a stretched polyethylene terephthalate film having an average thickness of 12 μm (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.) A-4: Stretched nylon film having an average thickness of 15 μm (“Emblem ON (registered trademark)” manufactured by Unitika)

[Second film]
The film shown below was used as the second film.
B-1: An ethylene-vinyl alcohol copolymer film having an average thickness of 12 μm (“EF-XL” manufactured by Kuraray Co., Ltd.)
B-2: Polyvinyl alcohol film having an average thickness of 12 μm (“Boblon EX (registered trademark)” by Nippon Synthetic Chemical Co., Ltd.)

  The average thickness of each film was obtained by cutting the multilayer sheet into 20 cm length and 20 cm width, and averaging the values measured at 9 locations with a thickness measuring instrument ("UPRIGHT DIAL GAUGE, No. 25" by PEACOCK). Asked.

[Example 1]
On the back side of (A-1) as the first film, dry laminate adhesive ("LX-500" from Dainippon Ink & Chemicals, "KR-90S" from Dainippon Ink & Chemicals, and ethyl acetate) The mixture was applied so that the solid content was 3.0 g / m ² and the solvent was evaporated at 80 ° C., and then the second film. (B-1) was bonded together and allowed to stand at 23 ° C. for 5 days. Next, on the back side of the second film (B-1), a batch type vapor deposition facility (“EWA-105” from Nippon Vacuum Engineering Co., Ltd.) was used, and the surface temperature of the second film (B-1) was set to 38 ° C. Was vapor-deposited so as to have an average thickness of 30 nm, and an inorganic vapor-deposited layer was formed to obtain a multilayer sheet.

[Examples 2 to 10 and Comparative Examples 1 to 9]
A multilayer sheet was obtained in the same manner as in Example 1 except that the type of film used, the components of the inorganic vapor deposition layer, and the average thickness were as shown in Table 1. In Table 1, “-” indicates that the component is not provided.

  In Example 4 and Comparative Example 4, an inorganic vapor deposition layer was formed from silicon oxide by the following method. The back surface of the second film (B-1) was subjected to plasma treatment with argon gas plasma using microwaves under conditions of a temperature of 40 ° C. and a pressure of 0.01 Pa. Subsequently, under the same conditions, a mixed gas of argon gas, silane, and oxygen is irradiated with microwaves to generate silicon oxide plasma, and plasma chemical vapor deposition is used as an inorganic vapor deposition layer on the back surface of the second film (B-1). A silicon oxide layer having an average thickness of 50 nm was formed. The composition of this silicon oxide layer was 1.8 mol of oxygen atoms per 1 mol of silicon atoms.

  Moreover, in Example 5 and Comparative Example 5, the inorganic vapor deposition layer was formed with the following method with the aluminum oxide. After the back surface of the second film (B-1) is subjected to corona discharge treatment, the laminated body of the first film (A-1) and the second film (B-1) is mounted on a delivery roll of a take-up vacuum deposition apparatus. did. Using aluminum as a deposition source and supplying oxygen gas, the degree of vacuum in the deposition chamber after introduction of oxygen gas is 0.02 Pa, the degree of vacuum in the take-up chamber is 2 Pa, and an electron beam with electron beam power (25 kW). (EB) A vacuum deposition method by a heating method was performed. Thereby, an aluminum oxide having an average thickness of 50 nm as an inorganic vapor deposition layer was formed on the back surface of the second film (B-1).

  Furthermore, in Examples 6 and 10 and Comparative Example 7, an aluminum-deposited stretched polyethylene terephthalate film (A-2) was used as the first film, and in Example 7, an aluminum-deposited stretched polyethylene terephthalate film (A-3) was used as the first film. ) Was used. The 2nd film (B-1) was laminated | stacked so that the surface by which aluminum was vapor-deposited in these films might become a back surface.

  In Example 8, (B-2) is used as the second film, (B-1) is used as the first film in Comparative Example 8, and (A-4) is used as the first film in Comparative Example 9. Was used.

  Further, in Example 9 and Comparative Example 6, a multilayer sheet was formed in the same manner as in Example 1 except that the average thickness of the inorganic vapor deposition layer was as shown in Table 1, and then an adhesive for dry lamination on the back surface of the inorganic vapor deposition layer Was applied, and (A-1) was used as the third film. This (A-1) was further bonded to the inorganic vapor-deposited layer to obtain a multilayer sheet having the third film on the back surface side. The composition and bonding method of the adhesive for dry lamination are the same as those used in the bonding of the first film and the second film.

  Further, in Example 10 and Comparative Example 7, a multilayer sheet was formed in the same manner as in Example 1 except that the average thickness of the inorganic vapor deposition layer was as shown in Table 1, and then an adhesive for dry lamination on the back surface of the inorganic vapor deposition layer Is applied, and (A-2) is used as the third film, the aluminum-deposited surface of (A-2) is further bonded to the inorganic vapor-deposited layer, and the third film is provided on the back surface side. A sheet was obtained. The composition and bonding method of the adhesive for dry lamination are the same as those used in the bonding of the first film and the second film.

<Evaluation>
Evaluation of the obtained multilayer sheet etc. was performed by the following method.

[Storage modulus and loss factor of the first film]
The storage elastic modulus and loss factor of the first film were measured using a dynamic viscoelasticity measuring device ("Rheogel-E4000" manufactured by UBM). The first film was cut into a length of 30 mm and a width of 5 mm, and the temperature was raised at a constant frequency (10 Hz) with a tensile mode sine wave at 10 ° C./min, and measurements from 0 ° C. to 120 ° C. were performed. Based on the measurement results, storage elastic moduli E ′ ₂₅ and E ′ _{100 and} loss factors tan δ ₂₅ and tan δ ₁₀₀ at 25 ° C. and 100 ° C. were determined.

[Average thickness of inorganic vapor deposition layer]
After the multilayer sheet is cut with a microtome to expose the cross section, this cross section is measured by using a backscattered electron detector of a scanning electron microscope (“ZEISS ULTRA 55” manufactured by S.I. Inano Technology). The average thickness of the deposited layer was measured.

<Manufacture of jacket material>
[Examples 1 to 8, Comparative Example 8 and Comparative Example 9]
An adhesive for dry laminating is applied to the back surface of the multilayer sheet, and (A-2) is used as the other layer constituting the jacket material. The layers were laminated together. Next, an adhesive for dry lamination was applied to the surface of the multilayer sheet, and an unstretched polypropylene film (CPP, “RXC-11” manufactured by Mitsui Chemicals, Inc.) with an average thickness of 50 μm was bonded, and further allowed to stand at 23 ° C. for 5 days. A sheath material was obtained. The composition and bonding method of the adhesive for dry lamination are the same as those used in the bonding of the first film and the second film.

[Example 9, Example 10, Comparative Example 6 and Comparative Example 7]
An adhesive for dry lamination is applied to the surface of the multilayer sheet, and an unstretched polypropylene film (CPP, “RXC-11” manufactured by Mitsui Chemicals, Inc.) with an average thickness of 50 μm is bonded, and then left to stand at 23 ° C. for 5 days. A substrate was obtained. The composition and bonding method of the adhesive for dry lamination are the same as those used in the bonding of the first film and the second film.

[Comparative Examples 1-5]
An adhesive for dry laminating is applied to the back surface of the multilayer sheet, and (A-2) is used as the other layer constituting the jacket material. The layers were laminated together. Thereafter, an adhesive for dry lamination is applied to the back side of the above (A-2), and (A-4) is used as another layer, and this (A-4) is used as the above (A-2). It was further bonded to the back side. Next, an adhesive for dry lamination was applied to the surface of the multilayer sheet, and an unstretched polypropylene film (CPP, “RXC-11” manufactured by Mitsui Chemicals, Inc.) with an average thickness of 50 μm was bonded, and further allowed to stand at 23 ° C. for 5 days. A sheath material was obtained. The composition and bonding method of these adhesives for dry lamination are the same as those used for bonding the first film and the second film.

<Manufacture of vacuum insulation>
Two jacket materials were made to face each other so that the CPP layer was inside, and a glass fiber as a core material was disposed between the jacket materials. Thereafter, the core material and the jacket material were sealed by heat-sealing under the condition of a vacuum degree of 0.5 Pa to obtain a vacuum heat insulating material. Both the average width and the average length of this vacuum heat insulating material were 60 cm, and the average thickness was 2 cm.

<Evaluation>
Table 2 shows the appearance and oxygen permeation amount of the multilayer sheets of Examples and Comparative Examples, the adhesion strength of the jacket material, and the thermal conductivity of the vacuum heat insulating material. In Table 2, “Thermal conductivity after 0 days” indicates the thermal conductivity immediately after production of the vacuum heat insulating material, and “Thermal conductivity after 50 days” is the vacuum heat insulating material after 50 days storage at 100 ° C. The thermal conductivity of is shown.

[Appearance of multilayer sheet]
A multilayer sheet (total length: 4000 m, width: 1 m) was horizontally loaded on a film winder at a distance of 50 cm between rolls and loaded, and wound at a winding tension of 5 kg / m. When the multilayer sheet was wound, a portion where the multilayer sheet was deformed by 5 cm or more in the width direction and deformed by 1 cm or more in the thickness direction of the multilayer sheet was defined as a local tarmi, and evaluated according to the following criteria.
A: No local tarmi is observed.
B: One local tarmi is recognized.
C: Two or more local tarmi are recognized.

[Oxygen transmission rate (OTR)]
Using an oxygen permeation measuring device (MOCON OX-TRAN 2/21 manufactured by Modern Control Co., Ltd.), a multi-layer sheet was attached under the condition of 100 ° C. and 0% RH so that the back side was directed to the carrier gas side. The amount of oxygen permeation (unit: mL / (m ² · day · atm)) was measured under conditions of atmospheric pressure and carrier gas pressure of 1 atm.

[Adhesion strength between second film and inorganic vapor deposition layer]
After partly peeling between the second film of the jacket material and the inorganic vapor deposition layer, a test piece having a width of 15 mm and a length of 150 mm was formed. About this test piece, using a T-type peel strength measuring device (“Autograph AGS-H” manufactured by Shimadzu Corporation), adhesion per width of 15 mm under the conditions of a peel rate of 250 mm / min, a temperature of 23 ° C., and a humidity of 50% RH. The force was measured 5 times and the average value was calculated.

[Thermal conductivity]
Using a thermal conductivity measuring instrument (“HC-074 / 600” manufactured by Eiko Seiki Co., Ltd.), one side of the vacuum heat insulating material was measured at 38 ° C. and the other side was measured at 12 ° C.

  As shown in Table 2, the multilayer sheets of the examples were excellent in appearance and the oxygen permeation amount was low. Moreover, the jacket material of the Example was excellent in the adhesive strength of a 2nd film and an inorganic vapor deposition layer. Furthermore, the vacuum heat insulating material of the Example had little deterioration of the heat insulation property in a high temperature environment. On the other hand, the multilayer sheet of the comparative example tended to be inferior in appearance, and had a large amount of oxygen permeation. Moreover, the coating material of the comparative example also had low adhesive strength of PVA (B) and an inorganic vapor deposition layer. In addition, the heat insulating property of the vacuum heat insulating material of the comparative example was greatly deteriorated in a high temperature environment.

  As described above, the multilayer sheet, the jacket material, and the vacuum heat insulating material of the present invention have low thermal conductivity and high gas barrier properties, and are excellent in long-term reliability under high temperature conditions. Moreover, the manufacturing method of the multilayer sheet of this invention can manufacture the said multilayer sheet easily and reliably.

DESCRIPTION OF SYMBOLS 1 1st film 1a Resin layer 1b Vapor deposition layer 2 2nd film 3 Inorganic vapor deposition layer 4 3rd film 4a Resin layer 4b Vapor deposition layer

Claims (11)

A first film mainly composed of a thermoplastic resin;
A second film that is laminated on one side of the first film and has a vinyl alcohol polymer as a main component;
A multilayer sheet comprising: an inorganic vapor deposition layer laminated on one surface of the second film;
The ratio of the storage elastic modulus at 100 ° C. to the storage elastic modulus at 25 ° C. in the first film is 60% or more,
The multilayer sheet, wherein the inorganic vapor deposition layer has an average thickness of 30 nm to 100 nm.   The multilayer sheet according to claim 1, wherein the first film has a resin layer containing the thermoplastic resin as a main component and a vapor deposition layer laminated on the resin layer.   The multilayer sheet according to claim 1 or 2, wherein the thermoplastic resin is polyester.   The multilayer sheet according to any one of claims 1 to 3, wherein the second film is a biaxially stretched film.   The multilayer sheet according to any one of claims 1 to 4, wherein an adhesion strength between the second film and the inorganic vapor deposition layer is 0.98 N / 15 mm or more. The multilayer sheet according to any one of claims 1 to 5, wherein an oxygen permeation amount at 100 ° C and 0% RH is 1.6 mL / (m ² · day · atm) or less. A third film laminated on one side of the inorganic vapor deposition layer;
The multilayer sheet according to any one of claims 1 to 6, wherein the third film has a resin layer mainly composed of a thermoplastic resin and a vapor deposition layer laminated on the resin layer.   An outer jacket material comprising the multilayer sheet according to any one of claims 1 to 7.   The vacuum heat insulating material provided with a core material and the jacket material of Claim 8 which vacuum-packs this core material.   The vacuum heat insulating material according to claim 9, wherein the thermal conductivity after storage for 50 days at 100 ° C is 10 times or less than the thermal conductivity before storage. A first film mainly composed of a thermoplastic resin;
A second film that is laminated on one side of the first film and has a vinyl alcohol polymer as a main component;
A method for producing a multilayer sheet comprising an inorganic vapor deposition layer laminated on one surface of the second film,
The ratio of the storage elastic modulus at 100 ° C. to the storage elastic modulus at 25 ° C. in the first film is 60% or more,
Laminating a second film on one side of the first film;
The method for producing a multilayer sheet according to claim 1, further comprising: laminating an inorganic vapor deposition layer on one surface of the second film by vapor deposition of an inorganic substance.

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