KR101399564B1 - Multilayer film and vacuum insulator plate - Google Patents

Abstract

An object of the present invention is to provide a multilayer film and a vacuum insulation structure excellent in gas barrier property even under high humidity and excellent in heat insulation performance. A multilayer film comprising a gas barrier film (A), a polyester film (B) and a polyolefin film (C) having a vapor permeability of 10 g / m 2 / day or less, and a multilayer film and a heat insulating material, Wherein the multilayer film encapsulates the heat insulating material.

Description

[0001] MULTILAYER FILM AND VACUUM INSULATOR PLATE [0002]

The present invention relates to a multilayered film and a vacuum insulation structure using the multilayered film. More particularly, the present invention relates to a multilayered film and a vacuum insulation structure excellent in gas barrier property even under high humidity and excellent in heat insulation performance.

Conventionally, a heat insulating material using a polyurethane foam has been used as a heat insulating material such as a refrigerator or an electric port, or a heat insulating panel for a heat insulating wall for a house. However, recently, as an excellent material replacing this, glasswool, silicon oxide, Of a heat insulating material as a core material is sealed with a gas barrier laminate film and a vacuum insulated structure in which the inside is vacuumed is beginning to be used.

In such a vacuum insulation structure, a polyvinyl alcohol film or a multi-layer structure using an aluminum foil is used as the gas barrier laminate film. As the vinyl alcohol film, a plastic film made of a polyvinyl alcohol resin, an ethylene- A multilayer structure using a film made of an alcohol copolymer or the like is used.

Examples of the vacuum insulation structure using such a multilayer structure using a vinyl alcohol film or an aluminum foil include a core material and a sheathing material encapsulating the core material. The sheathing material includes a laminate having a vapor deposition layer Wherein the laminated film having the vapor deposition layer and the laminated film having the aluminum foil is pouch-shaped by heat welding, and the laminated film having the vapor deposited layer is composed of the thermal welding layer, the gas barrier layer and the outermost layer , The gas barrier layer is formed by depositing aluminum on one side of a plastic film made of a vinyl alcohol based resin and a vacuum insulating body (see, for example, Patent Document 1) in which a surface subjected to aluminum vapor deposition is provided on the side of the thermal welding layer Has been proposed.

In addition, in the conventional vacuum insulation structure using a vinyl alcohol film, vapor-deposited PET is laminated on the outer side of the gas barrier layer, and a nylon film is laminated on the outermost layer in order to further secure gas barrier properties ( See, for example, Patent Document 2).

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 10-122477

[Patent Document 2] WO 2007/020978

Summary of the Invention

Problems of the Invention

However, since the aluminum foil is a positive conductor of aluminum, there is a drawback that the amount of heat passing through the aluminum portion in the film is large and the heat insulating performance deteriorates as the vacuum insulating structure. On the other hand, the layer structure in which the nylon film is the outermost layer has the disadvantage of insufficient gas barrier properties under high humidity. Since such a vacuum insulation structure is used in a heat insulation panel for a refrigerator or a thermal insulation wall for a house and is used in an environment susceptible to the influence of outside air, a vacuum insulation structure having sufficient gas barrier property for use under high humidity is required .

In view of the above, it is an object of the present invention to provide a multilayer film and a vacuum insulation structure excellent in gas barrier property even in use under high humidity, and excellent in heat insulation performance.

Means for solving the problem

The present inventors have conducted intensive studies in view of such circumstances. As a result, they have found that the gas barrier film (A), the polyester film (B) and the water vapor permeability of 10 g / day or less, a vacuum insulation structure excellent in gas barrier property and excellent in heat insulation performance can be obtained even under a high humidity. The present invention has been completed based on this finding.

That is, the gist of the present invention will be described below.

(1) A multilayer film comprising a gas barrier film (A), a polyester film (B) and a polyolefin film (C) having a vapor permeability of 10 g / m 2 / day or less and a heat insulating material, Wherein a film encapsulates the heat insulating material.

(2) The multilayered film has a layer structure of a gas barrier film (A) / a polyester film (B) / a polyolefin film (C) having a vapor permeability of 10 g / m 2 / day or less, The vacuum insulating structure according to the above (1), wherein the heat insulating material is sealed and packaged with the gas barrier film (A) inward.

(3) The vacuum insulation structure according to (1) or (2) above, wherein the gas barrier film (A) is a vinyl alcohol film.

(4) The vacuum insulation structure according to (3), wherein the vinyl alcohol film is a vinyl alcohol film deposited with aluminum.

(5) The vacuum insulation structure according to (3) or (4) above, wherein the vinyl alcohol film is a biaxially stretched polyvinyl alcohol film.

(6) The vacuum insulation structure according to any one of (1) to (5) above, wherein the polyester film (B) is a polyethylene terephthalate film deposited with aluminum.

(7) A multilayer film comprising a gas barrier film (A), a polyester film (B), and a polyolefin film (C) having a vapor permeability of 10 g / m 2 / day or less.

(8) The polyolefin film (C) as described in the above (7), wherein the film has a layer structure of a gas barrier film (A) / a polyester film (B) / a polyolefin film (V) having a vapor permeability of 10 g / ≪ / RTI >

(9) The multilayer film according to (7) or (8), wherein the gas barrier film (A) is a vinyl alcohol film.

(10) The multilayer film according to (9) above, wherein the vinyl alcohol film is a vinyl alcohol film deposited with aluminum.

(11) The multilayer film according to the above (9) or (10), wherein the vinyl alcohol film is a biaxially stretched polyvinyl alcohol film.

(12) The multilayer film according to any one of (7) to (11), wherein the polyester film (B) is a polyethylene terephthalate film deposited with aluminum.

Effects of the Invention

The multilayered film and the vacuum thermal insulating structure of the present invention can be manufactured by using a polyolefin film (C) having a water vapor transmission rate of 10 g / m < 2 > / day or less in sealing a package of a heat insulating material using a multilayer film, Excellent in heat resistance, and excellent in heat insulating property and moisture proofing property.

Carrying out the invention  Best form for

Hereinafter, the present invention will be described in detail.

The gas barrier film (A) used in the present invention is not particularly limited and may be a film having gas barrier properties. Usually, among these gas barrier films, a film having a gas barrier property of JIS K 7126 ( (M 2 · day · atm) or less (preferably 0.1 m 2 / (m 2 · day · atm) or less) when measured according to the method described in JP-A-11-19378 Concretely, a vinyl alcohol-based film is particularly preferable in terms of obtaining a high gas barrier property.

Such a vinyl alcohol-based film is formed by film formation from a vinyl alcohol-based resin. The vinyl alcohol-based resin is not particularly limited as long as it has a vinyl alcohol unit formed by saponifying a vinyl ester unit. Examples of the vinyl alcohol- Vinyl alcohol-based resins (hereinafter sometimes abbreviated as PVA resins), and ethylene-vinyl alcohol copolymers (hereinafter abbreviated as EVOH). Examples of the PVA-based resin include PVA obtained by homopolymerizing vinyl acetate and saponifying it, and modified PVA. Examples of such modified PVA include a copolymerized modified product and a back-modified product.

Hereinafter, each of the vinyl alcohol films will be described in detail.

First, the PVA resin will be described.

Examples of the PVA-based resin include PVA and modified PVA as described above, and PVA is prepared by homopolymerizing vinyl acetate and further saponifying it. The modified PVA is produced by copolymerizing vinyl acetate and unsaturated monomers copolymerizable with vinyl acetate and saponifying the copolymer, and the modified amount is usually less than 10 mol%.

Examples of the unsaturated monomer copolymerizable with vinyl acetate include olefins such as ethylene, propylene, isobutylene, alpha-octene, alpha -dodecene and alpha -octadecene, 3-butene- -Olefins and hydroxyl group-containing? -Olefins such as 5-hexene-1-ol and derivatives thereof such as acylates thereof, and the like, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid and undecylenic acid Unsaturated acids, salts thereof, monoesters or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as diacetone acrylamide, acrylamide and methacrylamide, ethylene sulfonic acid, allylsulfonic acid, meta Allyl sulfonic acids and the like, alkyl vinyl ethers, dimethyl allyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl- Dioxolane, glycerin monoallyl ether, 3,4-diacetoxy -1-butene and the like, substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate, vinylidene chloride, 1,4-diacetoxy-2-butene and vinylene carbonate, .

The modified PVA can also be produced by post-modification of PVA. Examples of such methods of subsequent denaturation include a method in which PVA is converted into acetic acid esterification, acetalization, urethanation, etherification, grafting, phosphoric esterification, and oxyalkylene.

In the present invention, the PVA resin preferably has a degree of polymerization of 1100 or more and an average degree of saponification of 90 mol% or more. A more preferable range of polymerization degree is 1100 to 4000, and a particularly preferable range is 1200 to 2600. If the degree of polymerization is too low, the mechanical strength tends to be lowered when the resulting film is used. If the degree of polymerization is too high, the workability at the time of film formation and stretching tends to decrease. A more preferred range of the average degree of saponification is from 95 mol% to 100 mol%, particularly preferably from 99 mol% to 100 mol%. When the average degree of saponification is too low, the water resistance is lowered, and the change due to the humidity of the gas barrier property tends to become remarkable.

The viscosity of the 4 wt% aqueous solution of the PVA resin is preferably 2.5 mPa · s to 100 mPa · s (20 ° C.), more preferably 2.5 mPa · s to 70 mPa · s (20 ° C.) More preferably 2.5 mPa · s to 60 mPa · s (20 ° C.). If the viscosity is too low, the mechanical properties such as the film strength tends to be poor, and if too high, the film-forming property to the film tends to deteriorate.

The viscosity is measured in accordance with JIS K6726.

These PVA resins may be used alone or in combination of two or more.

Next, the EVOH will be described.

In the present invention, any EVOH may be used as long as it is obtained by saponifying a copolymer of ethylene and vinyl ester. Typical examples of such vinyl esters include vinyl acetate, but other fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) Can be used. Further, the EVOH may contain 0.0002 mol% to 0.2 mol% of a vinylsilane compound as a copolymerization component in order to improve the stability during heating and melting. Examples of the vinylsilane-based compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (beta -methoxy-ethoxy) silane and gamma-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are suitably used. Further, other copolymerizable monomers such as propylene, butylene, and the like may be used as long as the object of the present invention is not impaired. Unsaturated carboxylic acids such as (meth) acrylic acid, methyl (meth) acrylate and ethyl (meth) acrylate; And vinyl pyrrolidone such as N-vinyl pyrrolidone.

In the present invention, the ethylene content of EVOH is 10 mol% to 60 mol%, and the ethylene content is preferably 15 mol% or more, particularly preferably 25 mol% or more, from the viewpoint of obtaining good stretchability. From the viewpoint of gas barrier properties, the ethylene content is preferably 55 mol% or less, and particularly preferably 50 mol% or less. If the ethylene content is too low, the melt moldability tends to deteriorate, while if too large, the gas barrier property tends to become insufficient.

The ethylene content of the EVOH can be determined by a nuclear magnetic resonance (NMR) method.

The degree of saponification of the EVOH is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more. When the degree of saponification is too low, the gas barrier property under high humidity tends to decrease.

Here, when the EVOH is a combination of two or more types of EVOH having different degrees of saponification, the average value calculated from the blend weight ratio is saponified.

A boron compound may also be blended in the EVOH in order to improve the stability during heating and melting within the range not hindering the object of the present invention. Examples of the boron compound include boric acids, boric acid esters, boric acid salts and boron hydrides. Specific examples of the boric acid include orthoboric acid, meta boric acid, and tetraboric acid. Examples of the boric acid ester include triethyl borate and trimethyl borate. Examples of the borate include alkali metal salts, alkaline earth metal salts , Borax and the like. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferable.

When the EVOH is blended with the boron compound, the content of the boron compound is preferably 20 ppm to 2000 ppm, more preferably 50 ppm to 1000 ppm in terms of the boron element. By blending the boron compound within this range, it is possible to obtain an EVOH in which the torque fluctuation during heating and melting is suppressed. If the content of the boron compound is too small, the effect of addition is small, and if it is excessively large, gelation tends to occur, resulting in poor moldability.

The suitable melt flow rate (MFR) (at 230 DEG C under a load of 2160 g) of EVOH is generally from 1 g / 10 min to 50 g / 10 min, more preferably from 3 g / 10 min to 40 g / 10 min , Even more preferably from 5 g / 10 min to 30 g / 10 min. These EVOHs may be used alone or in combination of two or more.

In the present invention, film formation is performed using the above-mentioned vinyl alcohol resin. However, such a film formation method is not particularly limited. For example, a vinyl alcohol resin solution is cast on a metal surface such as a drum or endless belt, Or by melt extrusion using an extruder.

Thus, in the present invention, the vinyl alcohol-based film used as the gas barrier film (A) is produced. The vinyl alcohol film may be used as it is, but it is also preferably used as a uniaxially or biaxially stretched vinyl alcohol film by stretching treatment. In view of gas barrier property, a biaxially oriented vinyl alcohol film And is particularly preferably used.

Such a stretching treatment method can be carried out according to a known method such as a uniaxial stretching method which is usually carried out, a simultaneous biaxial stretching, a biaxial stretching, or the like.

In the present invention, among these biaxially oriented polyvinyl alcohol films, biaxially oriented PVA films and biaxially oriented EVOH films are particularly preferably used.

First, the biaxially stretched PVA film will be described.

(PVA film before stretching) using the above PVA resin, but usually the PVA resin concentration is 5% by weight to 70% by weight, preferably 10% by weight % To 60% by weight of PVA resin-water.

Such a PVA resin-water composition may contain various additives such as plasticizers for polyhydric alcohols such as ethylene glycol, glycerin, polyethylene glycol, diethylene glycol and triethylene glycol, antioxidants such as phenol and amine, Conventional additives such as stabilizers, coloring agents, flavorings, extenders, antifoaming agents, exfoliating agents, ultraviolet absorbers, inorganic powders and surfactants may be appropriately mixed. Further, water-soluble resins other than PVA-based resins such as starch, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose and the like may be mixed.

The method of forming the PVA film is not particularly limited, but it is preferable to apply the PVA resin-water composition to an extruder, melt-knead, extrusion-form the film according to the T-die method, inflation method, and dry.

In this method, the melt-kneading temperature in the extruder is preferably 55 ° C to 160 ° C. When the temperature is too low, the surface of the film is defective. When the temperature is too high, the film tends to cause a foaming phenomenon. The drying of the film after film formation is preferably performed at 70 to 120 캜, and more preferably at 80 to 100 캜.

The biaxial stretching is further performed on the PVA film obtained above to obtain a biaxially oriented PVA film preferably used in the present invention.

With respect to such biaxial stretching, it is preferable that the stretching magnification in the machine direction (MD direction) is 2.5 to 5 times, the stretching magnification in the width direction (TD direction) is 2 to 4.5 times, Is 3 to 5 times, and the stretching magnification in the TD direction is 2.5 to 4.5 times. If the stretching magnification in the MD direction is too low, improvement in physical properties due to stretching is difficult to obtain and heat resistance tends to be impaired. If too high, the film tends to be torn in the MD direction. If the stretching ratio in the TD direction is too low, improvement in physical properties due to stretching is obtained, and heat resistance tends to be impaired. When the stretching ratio is too high, the film tends to break frequently during stretching have.

In the case of such sequential biaxial or simultaneous biaxial stretching, it is preferable to adjust the water content of the PVA-based film to 5 wt% to 30 wt%, particularly 20 wt% to 30 wt%. The moisture content can be adjusted by a method of continuously drying the PVA film before drying, a method of immersing or moisturizing the PVA film having a moisture content of less than 5% by weight, and the like. If the water content is too low or too high, the draw ratio in the MD and TD directions tends not to be increased in the stretching process.

It is preferable to perform heat fixation after the biaxial stretching, and it is preferable to select a temperature lower than the melting point of the PVA-based resin, particularly preferably 140 to 250 ° C . When the heat-setting temperature is lower than the melting point by 80 占 폚 or more, the dimensional stability is poor and the shrinkage ratio tends to become large. On the other hand, when the heat-setting temperature is higher than the melting point, the thickness variation of the film tends to increase. The heat setting time is preferably from 1 second to 30 seconds, more preferably from 5 seconds to 10 seconds.

If necessary, for the purpose of further reducing the thermal deformation, such biaxially oriented PVA film may be contacted with an aqueous solution and processed for drying. In contact with the aqueous solution, an aqueous solution of usually 5 ° C to 60 ° C, preferably 10 ° C to 50 ° C is used. The contact time with the aqueous solution is appropriately selected according to the temperature of the aqueous solution, Sec to 60 sec.

The method of contacting with such an aqueous solution is not particularly limited, and examples thereof include a method of spraying an aqueous solution or an aqueous solution, an application of an aqueous solution, a steam treatment, or the like, and these methods may be used in combination. After contact with an aqueous solution, it is industrially preferable to remove water adhered to the surface by non-contact contact with an air shower or the like, followed by contact water removal with niprol or the like. The type of the drier is not particularly limited, and examples thereof include a method of directly contacting with a metal roll or a ceramic roll, drying, or a method using a non-contact type dryer.

When the obtained biaxially oriented PVA-based film is rolled again after contacting with the aqueous solution and drying, it is required that the water content of the film is usually 3 wt% or less, preferably 0.1 wt% to 2 wt% do. If the moisture content is too large, there is a tendency that the films are closely adhered to each other in the film roll, and there is a possibility that the film may be damaged when the film is unwound again for processing.

Thus, a biaxially oriented PVA film suitably used in the present invention can be obtained.

Next, the biaxially stretched EVOH film will be described.

An EVOH film (EVOH film before stretching) is formed by using the EVOH.

Such an EVOH may contain various additives such as an antioxidant, a coloring material, an ultraviolet absorber, a slip agent, an antistatic agent, a plasticizer, a crosslinking agent such as boric acid, an inorganic filler, and an inorganic desiccant , Polyamide, polyolefin, and superabsorbent resin.

When forming the EVOH film using the EVOH, the melt molding is mainly used. Hereinafter, the melt molding method will be described.

The conditions for such melt molding are not particularly limited, but usually extrusion is performed at a melting temperature of 190 to 250 캜 using a non-vent, screw type extruder. Normally, a screw having a compression ratio of 2.0 to 4.5 is used, and the film is formed using a T die or a circular die.

The EVOH-based film can be obtained in this way. The biaxially stretched EVOH-based film can be formed by biaxial stretching, preferably sequential biaxial stretching.

The area ratio of such biaxial stretching is preferably 3 times or more, more preferably 6 times or more, particularly preferably 9 times or more, from the viewpoints of gas barrier property and mechanical strength. As the stretching method, a known stretching method such as a single biaxial stretching method such as a double bubble method, a tensile method and a roll method can be employed. In the case of biaxial stretching, any method of simultaneous stretching and stretching stretching can be employed Can be adopted.

The water content of the raw material film before stretching is preferably 2% by weight to 30% by weight, more preferably 5% by weight to 30% by weight By weight, particularly preferably 10% by weight to 30% by weight. If the water content is too low, unevenness in stretching tends to remain, and in particular, in the case of stretching by tenter, the stretching magnification of a portion close to the grip becomes high, so that tearing near the grip may easily occur. On the other hand, if the moisture content is too high, the elastic modulus of the stretched portion is low, and the difference from the unstretched portion is insufficient, and the unevenness of stretching may be easily left.

The stretching temperature is somewhat different depending on the moisture content of the raw material film before stretching, but the range of 50 占 폚 to 130 占 폚 is generally adaptable. Particularly in simultaneous biaxial stretching, it is easy to obtain a biaxially stretched EVOH-based film having a small thickness unevenness in the range of 70 to 100 占 폚. In the case of continuous biaxial stretching, stretching in the longitudinal direction of the roll, It is easy to obtain a biaxially oriented EVOH-based film having a small thickness unevenness by performing the stretching in the width direction of the taro in the temperature range of 80 to 120 캜.

A more important factor concerning the production of the biaxially oriented EVOH-based film is the heat treatment after stretching and the density and water content of the biaxially oriented EVOH-based film obtained as a result of the heat treatment. The heat treatment is preferably performed at a temperature lower by 5 캜 to 40 캜 than the melting point of EVOH for 5 seconds to 20 seconds. If the heat treatment temperature is too low, the heat treatment may be insufficient, so that heat resistance and gas barrier properties sufficient to withstand the vapor deposition process may not be obtained. On the other hand, if the heat treatment temperature is excessively high, the stretching effect may be partially reduced.

Thus, a biaxially oriented EVOH-based film suitably used in the present invention can be obtained.

The thickness of the gas barrier film (A) used in the present invention is usually from 5 m to 100 m, preferably from 8 m to 50 m, and particularly preferably from 8 m to 30 m, from the viewpoint of industrial productivity It is advantageous.

Since the gas barrier film (A) alone has sufficiently low thermal conductivity, high gas barrier property and heat resistance, it can be sufficiently used as a gas barrier layer. However, for the purpose of further imparting heat radiation comparable to aluminum foil, It is preferable to deposit a metal or metal oxide or to provide a coating layer. Of course, the vapor deposition layer and the coating layer may be used together.

When the vapor-deposition film is applied to the gas-barrier film (A), the metal or the metal oxide used for the vapor-deposition layer is not particularly limited, and examples thereof include aluminum, gold, silver, copper, nickel, cobalt, Tin or the like, or metal oxides thereof. Of these, aluminum, gold, silver and tin are preferably used, and aluminum is preferably used in terms of cost.

As a method of depositing the metal or metal oxide, it is preferable to continuously perform vapor deposition processing to obtain a vapor-deposited layer having a more uniform thickness for the gas-barrier film (A), for example. In this continuous evaporation processing, there is a step of instantly receiving the material of the deposition layer of the metal or metal oxide heated to 1000 캜 or more, while always keeping the uniform running of the film running over the entire width of the cooling drum , It is important that the shape stability of the film is maintained even under such harsh manufacturing conditions.

The thickness of the deposition layer formed on the surface of the gas barrier film (A) is preferably 200 A to 1200 A (Angstrom), more preferably 350 A to 1000 A. If the thickness of the deposition layer is too thin, it is difficult to obtain heat radiation characteristics. If the thickness of the deposition layer is too thick, the deposition time for obtaining the thickness tends to be too long, and the thermal influence at the time of deposition tends to be excessively large. Can not do it.

Further, in carrying out the vapor deposition on the surface of the gas barrier film (A), the surface of the gas barrier film (A) may be pretreated for the purpose of further improving the adhesion with the vapor deposition layer. Examples of the pretreatment include a method of promoting the activation of the substrate itself such as a corona treatment and a method of forming a thin film layer using a coating agent such as a urethane hardener using polyethylene or polyether as a main agent.

On the other hand, in the case of applying the coating layer, it is possible to select an optional coating material, but from the viewpoint of heat radiation characteristics, the reflectance of the coating layer is preferably 60% or more, particularly preferably 80% or more, , Silver, and the like are suitably used. The method of forming the coating layer is not particularly limited, but it is practical that a commercially available coating material is applied by a printing method such as gravure printing, offset printing or flexographic printing.

The binder for the gas barrier film (A) and the coating layer is not particularly limited, but it is preferable to blend a urethane curing agent with the binder in terms of adhesion.

In carrying out the coating layer on the surface of the gas barrier film (A), the surface of the vinyl alcohol film (A) may be pretreated for the purpose of further improving adhesion with the coating layer. Examples of the pretreatment include a method of promoting the activation of the substrate itself such as corona treatment and a method of forming a thin film layer using a coating agent such as a urethane hardener based on polyethylene or polyether.

The polyester film (B) used in the present invention is a film made of a polyester resin, and the polyester resin is composed of an acid component and a glycol component.

Examples of such an acid component include, but are not limited to, terephthalic acid, oxalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, succinic acid, adipic acid, Dicarboxylic acids such as dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, 4-hydroxybenzoic acid, ε- Caprolactone, oxycarboxylic acids such as lactic acid, and the like.

Examples of such glycol components include, but are not limited to, ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene Glycols such as glycol, polypropylene glycol, and polytetramethylene glycol.

By copolymerizing the acid (component) and the glycol (component), the polyester resin used in the present invention can be obtained. The combination of the positive components is not particularly limited, and a copolymer obtained by copolymerization in any combination can be used. Among them, polyethylene terephthalate, polyethylene naphthalate and polycyclohexylenedimethylene terephthalate are preferably used And polyethylene terephthalate is particularly preferably used.

The polyester film (B) used in the present invention may be a mixture of two or more of the above-mentioned polyester resins, or a mixture of other thermoplastic resins.

The polyester film (B) may also contain an inorganic particle such as silica, calcium carbonate, or titanium oxide, acrylic acid, styrene or the like, such as an ultraviolet absorber, an antioxidant, an antistatic agent, a surfactant, a pigment, Organic particles may also be appropriately contained as needed.

The production method of the polyester film (B) is not particularly limited, and a known production method can be used. For example, a method of transesterification from dimethyl terephthalate and ethylene glycol, or a method of obtaining an oligomer by direct esterification from terephthalic acid and ethylene glycol, followed by melt polymerization or solid state polymerization.

The polyester film (B) thus obtained may be used as it is, but it is also preferable to use it as a uniaxially or biaxially stretched polyester film by conducting a stretching treatment. Particularly, And a gas barrier property, a biaxially oriented polyester film is preferably used.

As a method for producing such a biaxially stretched polyester film, a publicly known method can be used. For example, the following methods can be used.

First, a polyester chip is put into an extruder, heated and melted, extruded into a sheet form from a die orifice of a T die, and brought into close contact with a cooling drum by an electrostatic casting method and the like. Subsequently, stretching is performed at a temperature of 85 to 140 占 폚 at a magnification of 2.5 to 5.0 times the length and width, respectively, and further heat treatment is performed at a temperature of 200 占 폚 to 245 占 폚 to obtain a biaxially stretched film. When the stretching temperature is too low, a homogeneous stretched film tends not to be obtained. When the stretching temperature is too high, the crystallization of the polyester tends to be promoted and the transparency tends to deteriorate. If the stretching magnification is too low, the strength of the resulting stretched film is low. If the stretching magnification is too high, stretching tends to be difficult. If the heat treatment temperature is too low, the resulting stretched film has a high heat shrinkage ratio and a poor dimensional stability. If the heat treatment temperature is too high, melting of the film may occur.

The biaxial stretching method may be either a simultaneous biaxial stretching method using tenter or a sequential biaxial stretching method using roll and tenter. In addition, a biaxially oriented film may be produced by a tubular method. Such a biaxially oriented film can be subjected to a corona discharge treatment, a surface hardening treatment, a plating treatment, a coloring treatment, or a surface treatment by various coating treatments.

Though the thickness of such a polyester film (B) is not particularly limited, it is usually 5 m to 200 m, particularly preferably 10 m to 100 m. On the other hand, if the thickness is excessively thin, the workability tends to become poor as well as to become uneconomical.

In the polyester film (B) used in the present invention, a metal or a metal oxide is preferably deposited for the purpose of improving barrier properties and gas barrier properties of water vapor. The metal or the metal oxide used for the deposition layer is not particularly limited, and for example, a metal or a metal oxide such as aluminum, gold, silver, copper, nickel, cobalt, chromium, and tin may be used. Of these, aluminum, gold, silver and tin are preferably used, and aluminum is preferably used in terms of cost. The thickness of such a vapor deposition layer is not particularly limited, but is usually from 50 A to 1000 A, and particularly preferably from 200 A to 1000 A. The vapor deposition method of the polyester film (B) may be carried out in accordance with a method of vapor-depositing the vinyl alcohol film (A).

The polyolefin-based film (C) used in the present invention is a film containing a polyolefin-based resin, and has a water vapor permeability of 10 g / m 2 / day or less, particularly preferably 8 g / m 2 / day or less. If the water vapor permeability is too high, the gas barrier property under high humidity is deteriorated and the heat insulating performance tends to be deteriorated.

This water vapor permeability was measured in accordance with the method described in JIS K7129 (method A) under the condition of 40 DEG C-90% RH.

The low water vapor permeability of the polyolefin film (C) is an important factor for improving the gas barrier property under high humidity, which is the object of the present invention, and improving the heat insulating performance.

Examples of such a polyolefin resin include, but are not limited to, homopolymers such as polypropylene, polybutene-1, high-density polyethylene, medium-density polyethylene and low-density polyethylene, Hexene-1, octene-1, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 1,4-hexadiene, styrene And the copolymer is graft-modified with a carboxylic acid such as maleic anhydride, a copolymer obtained by graft-copolymerizing ethylene, propylene, butene-2, isobutylene, butadiene, pentene- , 4-methylpentene-1, hexene-1, octene-1 and the like, and graft-modified copolymers of these with carboxylic acids such as maleic anhydride, propylene, butene- 1, 1-hexene, 1-octene, 5-ethylidene-2-norbornene, 5-methylene- Butene, styrene, vinyl acetate, methyl acrylate, ethyl acrylate, acrylic acid, methyl methacrylate, ethyl methacrylate, methacrylic acid, glycidyl methacrylate and the like, and copolymers of these copolymers with maleic anhydride And graft-modified with carboxylic acid. Of these, polypropylene is particularly preferred from the viewpoint of moisture resistance and industrial productivity.

The copolymer of the copolymer with acrylic acid or methacrylic acid may be crosslinked with sodium, zinc, aluminum or the like, and a copolymer of vinyl acetate with the vinyl acetate component may be partially saponified or partially saponified. The polyethylene may be graft-modified with a carboxylic acid such as maleic anhydride.

The polyolefin film (C) may further contain additives such as antioxidants, heat stabilizers, weathering stabilizers, antistatic agents, slip agents, anti-blocking agents, antifogging agents, lubricants, dyes, pigments, Natural oils, synthetic oils, waxes, fillers and the like may be blended as required.

The polyolefin-based resin composition used in the present invention is not particularly limited. For example, the polyolefin-based resin composition is melted by an extruder, extruded from a T-die into a sheet, cooled and solidified by a cooling roll, And a method for producing a new sheet.

The polyolefin film (C) thus obtained may be used as it is, but it is preferably used as a uniaxially stretched or biaxially stretched polyolefin film by stretching treatment, and in particular, A biaxially oriented polyolefin-based film is preferably used in view of obtaining gas barrier properties.

As a method for producing such a biaxially stretched polyolefin-based film, a known method can be used. The stretching magnification is preferably 1.5 to 6 times in the longitudinal direction and 1.5 to 10 times in the transverse direction. In addition, longitudinal and transverse stretching may be performed at the same time or separately. In the case of separately performed, the longitudinal stretching is preferably performed at a temperature of 110 ° C to 130 ° C, and the transverse stretching is performed at a temperature of 150 ° C to 165 ° C .

The biaxial stretching method may be either a simultaneous biaxial stretching method using tenter or a sequential biaxial stretching method using roll and tenter. Further, a biaxially oriented film may be produced by a tube method.

The polyolefin film (C) can be subjected to a surface treatment by corona discharge treatment, surface hardening treatment, plating treatment, coloring treatment or various coating treatments, if necessary.

The thickness of such a polyolefin-based film (C) is not particularly limited, but it is usually preferably 5 to 200 μm, particularly preferably 10 to 100 μm. If the film thickness is too thin, tearing or the like tends to occur at the time of processing. If the film thickness is excessively large, not only the workability is deteriorated but also it tends to become uneconomical.

The multilayer film in the present invention may be any film as long as it comprises at least three layers of the gas barrier film (A), the polyester film (B) and the polyolefin film (C) having a transmittance of 10 g / . The order of lamination of these three layers is not particularly limited, and the order of lamination of the three layers is not particularly limited, and the order of lamination of the three layers is not particularly limited. (C) / (B) / (A), (B), (C) Is particularly preferable in view of gas barrier properties under high humidity.

In the multilayered film, the film thickness ratio between the respective layers of the gas barrier film (A), the polyester film (B) and the polyolefin film (C) The thickness of the ester film (B) is usually 0.5 to 3, preferably 0.8 to 2, and the thickness of the polyolefin film (C) is usually 0.5 to 8, preferably 0.5 to 5.

These three layers may be laminated successively in this order, and another layer such as a pressure-sensitive adhesive layer, a seal layer, or the like may be provided between the layers or outside.

With respect to the bonding method of each layer in such a multilayered film, a method (lamination method) using a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester compound is preferably used (dry lamination method). However, the present invention is not limited to these methods.

In the present invention, the heat insulating structure is formed by sealing the heat insulating material by using the multilayer film thus obtained.

The packaging method of the heat insulating material is not particularly limited. For example, a method of forming an external pouch in which a multilayered film is processed into a pouch type, and inserting a heat insulating material therein can be used.

In this manner, when forming the outer pouch with the multilayer film, it is preferable that the multilayer film has a seal layer on the inner side of the outer pouch. Although not particularly limited as the sealing layer, a polyolefin-based resin layer is preferable from the viewpoint of sealing strength, and among these, polypropylene, high-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer and the like are suitably used. As for the seal layer, a separate film may be prepared from the resin to further laminate on the inner side of the outer pouch, or may be laminated directly onto the inner side of the outer pouch. When the seal layer is laminated as a film, lamination as a non-oriented film is advantageous in that sealing property is obtained. The thickness of the seal layer is not particularly limited, but is usually 10 mu m to 100 mu m, particularly preferably 20 mu m to 80 mu m.

Although the thickness of the entire multilayer film in the present invention is not particularly limited, it is usually preferably 20 to 800 占 퐉, particularly preferably 50 to 500 占 퐉.

As a preferable layer structure when the heat insulating material is sealed and packed using the multilayer film of the present invention, from the viewpoint of gas barrier property and moisture-proof property, from the outer layer side (opposite to the heat insulating material)

(1): Biaxially oriented polypropylene film // Adhesive layer // Aluminum vapor deposition layer / PET film // Adhesive layer // Aluminum vapor deposition layer / Biaxially oriented PVA film // (Adhesive layer) // Polyethylene layer )

(2): Biaxially oriented polypropylene film // Adhesive layer // PET film / Aluminum vapor deposition layer // Adhesive layer // Aluminum vapor deposition layer / Biaxially oriented PVA film // (Adhesive layer) // Polyethylene layer )

(3): Biaxially oriented polypropylene film // Adhesive layer // Aluminum vapor deposition layer / PET film // Adhesive layer // Aluminum vapor deposition layer / Biaxially oriented EVOH film // Adhesive layer // Polyethylene layer )

(4): biaxially oriented polypropylene film // adhesive layer // PET film / aluminum vapor deposition layer // adhesive layer // aluminum vapor deposition layer / biaxially oriented EVOH // (adhesive layer) // polyethylene layer

, But the present invention is not limited to such a layer structure.

The heat insulating material to be contained in the outer pouch made of the multilayer film is not particularly limited, but a polymer having open cells inside, or a fine powder of an inorganic substance or a metal is preferably used. Even if the inside of the outer pouch made of a multilayer film is in a vacuum state, . In the case where the inside of the outer pouch made of the multilayer film is in a vacuum state and the openings are sealed and used, if the polymer of the heat insulating material has no bubbles or has closed cells, the heat insulating effect of the vacuum insulating structure is reduced not.

Specific examples of such a heat insulating material include fine powder such as alumina, silica and pearlite, glass surface, rockwool, diatomaceous earth, calcium silicate molded article, urethane foam having open cells, carbon foam, phenol foam, phenol- . Among them, a polymer having open cells is preferably used.

In addition, it is also preferable that such a heat insulating material be mixed with a drying agent such as silica gel or calcium chloride, because the water contained in the gas barrier film (A) used may cause a decrease in the degree of vacuum.

This heat insulating material is put in an external pouch made of a multilayer film and reduced in pressure, and finally the opening of the pouch is sealed and closed to obtain a vacuum heat insulating structure. The degree of vacuum of this vacuum thermal insulating structure is not particularly limited, but is preferably 1 Torr or less, more preferably 0.8 Torr or less, particularly preferably 0.6 Torr or less.

In the present invention, the shape and size of the vacuum thermal insulating structure are not particularly limited, and may be determined according to the purpose. For example, as for the shape of the vacuum insulation panel, it may be a configuration in which one external pouch made of a multilayer film is included in one vacuum insulation panel, and a configuration in which a plurality of external pouches are included in one vacuum insulation panel It is good.

In the case of a shape including a plurality of such external pouches, the seal portion serving as a joint between the external pouch portions becomes a thin portion in the vacuum heat insulating structure, and becomes a central portion of deformation in the case of deforming the vacuum heat insulating structure. The vacuum insulating structure can be easily deformed.

In addition, even when a hole or the like is generated due to an external factor and the vacuum property of the vacuum heat insulating structure is lost, a shape including a plurality of external pouches is preferable because the decrease in heat insulating property can be minimized.

With respect to the size of such a vacuum thermal insulating structure, the thickness is generally 5 mm to 100 mm, and the length and width are often processed into a rectangular parallelepiped shape having a range of 100 mm to 1000 mm. If the volume of the vacuum heat-insulating structure is unnecessarily large, the area in which the performance is lost in the case where a defect such as a hole is formed in the pouch of the multilayered film becomes large and the performance of the final product using the vacuum heat- .

Thus, according to the present invention, it is possible to obtain a vacuum thermal insulating structure which is excellent in heat insulating performance and does not cause deformation due to small heat shrinkage. Such a vacuum insulating structure may be used for various household appliances such as household appliances such as a cooler box and a bottle case, household appliances such as a refrigerator, a thermos bottle, a rice cooker, a home appliance such as a water heater, a bathtub, a unit bath, Housing systems such as low-temperature radiation panels, and home building materials such as insulation panels for outer walls. Among them, particularly, they can be particularly suitably used as a heat insulating material for a refrigerator.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a layer construction diagram of the multilayer film obtained in Example 1. Fig.

<Description of Symbols>

1: Biaxially oriented polypropylene film

2: Adhesive layer

3: Aluminum vapor deposition layer

4: PET film

5: Adhesive layer

6: Aluminum vapor deposition layer

7: Biaxially oriented PVA film

8: polyethylene layer (seal layer)

Hereinafter, the present invention will be described more concretely with reference to examples, but the present invention is not limited to the following examples unless they exceed the gist of the present invention.

In the examples, &quot; part &quot; and &quot;% &quot; means weight basis unless otherwise specified.

&Lt; Example 1 >

(Having a viscosity of 40 mPa s and a degree of saponification of 4% by weight in aqueous solution of 1700, polymerization degree: 1700) was fed from a hopper of a twin screw extruder type kneader (screw L / D = 40) 99.7 mol%, sodium acetate content 0.3%, "Gosenol NH-17Q" manufactured by Nippon Seika Kagaku Co., Ltd.) and water at a weight ratio of PVA / water of 40/60 by weight, and kneaded to give a discharge amount of 500 kg / hr. &lt; / RTI &gt;

The discharged material was immediately fed to a single-screw extruder (screw L / D = 30) and kneaded at a temperature of 85 to 140 DEG C. The extruded material was then extruded into castrol at 5 DEG C on a T-die and dried in a hot air drier at 90 DEG C for 30 seconds And dried to prepare a PVA film having a water content of 25% (thickness 150 탆). Subsequently, this PVA film was stretched 3.8 times in the MD direction, then stretched 3.8 times in the TD direction in the tensa, and then opened and fixed at 180 占 폚 for 8 seconds to obtain a biaxially oriented PVA film (thickness 12 占 퐉).

On one side of the obtained biaxially oriented PVA film, metal aluminum was evaporated by a vacuum evaporator according to an electron beam heating method, and aluminum of 700 Å in thickness was vapor deposited to obtain an aluminum evaporated biaxially oriented PVA film.

The non-deposited side of the aluminum evaporated surface side of the obtained aluminum-deposited biaxially oriented PVA film and the aluminum evaporated polyethylene terephthalate (PET) film ("VM-PET1510" After bonding at 70 占 폚 by a two-pack type polyurethane adhesive ("Takelak A-3210" manufactured by Takeda Yakuhinha Corporation / "Takenate A-3072" manufactured by Takeda Yakuhinha Corporation = 3/1 (weight ratio) For 2 days to obtain a laminate.

Further, commercially available biaxially oriented polypropylene ("OP U-1 # 20" manufactured by Tohcello Co., Ltd., water vapor permeability = 5.38 g / m 2 / day; thickness: 20 μm) was similarly adhered to the vapor deposition surface of the laminated aluminum- Further, hot-melted high-density polyethylene ("Nova Tech HD LY20" manufactured by Nippon Polyethylene Sha) was extruded from a T-die coater at a setting of 315 ° C on the exposed side of the biaxially oriented PVA film, Layer structure = biaxially oriented polypropylene film (1) // adhesive layer (2) // aluminum deposition layer (3) / PET film (4) // adhesive layer (5) // Aluminum vapor deposition layer 6 / biaxially oriented PVA film 7 / poly ethylene layer 8 (seal layer), which are schematically shown in Fig. 1.

The resulting multilayer film was molded into a square of 20 cm in length and 20 cm in width and polymerized so that the laminated high-density polyethylene layers were joined together. The peripheral portions around the three sides were sealed with a width of 1 cm ), And a glass side piece (25 mm in thickness) ("Magroll RR2425" manufactured by Maghrea) cut into 17 cm long and 17 cm wide was placed inside the obtained pouch-type multilayer structure, and this was placed in a vacuum packaging apparatus at 0.01 Torr , The remaining one opening was thermally fused under the same conditions as the previous one to obtain a vacuum thermal insulating structure.

&Lt; Example 2 >

Except that the aluminum evaporated surface of the aluminum evaporated biaxially oriented PVA film and the unvaporized surface of the aluminum evaporated PET film were bonded to each other by an adhesive on the aluminum evaporated surface of the aluminum evaporated PET film in Example 1 Layer structure = biaxially oriented polypropylene film // adhesive layer // PET film / aluminum vapor deposition layer // adhesive layer // aluminum vapor deposition layer / biaxially oriented PVA film // polyethylene layer ( Seal layer)]

&Lt; Example 3 >

Except that a commercially available aluminum-evaporated biaxially stretched EVOH film ("VM-EVOH" manufactured by TOYOTA METALIZING Co., Ltd., thickness: 12 μm) was used in place of the aluminum evaporated biaxially oriented PVA film in Example 1 Layer structure = biaxially stretched polypropylene film // adhesive layer // aluminum vapor deposition layer / PET film // adhesive layer // aluminum vapor deposition layer / biaxially oriented EVOH film // polyethylene layer &lt; tb &gt; (Seal layer)]

&Lt; Comparative Example 1 &

Except for using a commercially available nylon film ("Spanil SPR" manufactured by Mitsubishi Jusha Co., Ltd., water vapor transmission rate: 200 g / m 2 / day; thickness: 15 탆) instead of the biaxially stretched polypropylene film in Example 1, Layer structure = nylon film // adhesive layer // aluminum vapor deposition layer / PET film // adhesive layer // aluminum vapor deposition layer / biaxially oriented PVA film // polyethylene layer (seal layer )]

&Lt; Comparative Example 2 &

Except that a commercially available straight-chain low-density polyethylene ("TUX FCD # 25" manufactured by Tohcello Co., Ltd., water vapor permeability = 22.4 g / m 2 / day; thickness: 25 μm) was used in place of the biaxially stretched polypropylene film in Example 1, Layer structure = polyethylene film // adhesive layer // aluminum vapor deposition layer / PET film // adhesive layer // aluminum vapor deposition layer / biaxially oriented PVA film // polyethylene layer ( Seal layer)]

The following evaluations were made on the multilayered film and the vacuum thermal insulating structure obtained in the above Examples and Comparative Examples. The evaluation results are shown in Table 1.

<Oxygen Permeability>

The oxygen permeability of the multilayered film was measured at 23 占 폚 -50% using a MOCON OX-TRAN2 / 20 model (detection limit value 0.01 ml / (m2 占 day 占 atm) manufactured by MODERN CONTROLS.INK) RH in accordance with the method described in JIS K 7126 (equivalent pressure method). The oxygen permeability in the present invention is the transmittance [ml / (m2 · day · atm)] measured at an arbitrary film thickness. When the oxygen permeation amount is equal to or less than the detection limit value of the above-described apparatus, it is described as? 0.01.

<Vapor Transmission Rate>

The multilayered film was subjected to heat treatment under the conditions of 40 ° C-90% RH using a L80-5000 type water vapor transmission meter (detection limit value 0.01 g / m 2 / day) (manufactured by Lyssysch) Method. The transmittance referred to in the present invention is a value (g / m 2 / day) measured at an arbitrary film thickness. When this water vapor permeability is equal to or less than the detection limit value of the above-described apparatus, it is described as? 0.01.

<Insulation effect>

The vacuum insulation panels of Examples 1 and 2 and Comparative Examples 1 and 2 were placed in a thermostatic chamber at 40 占 폚 and 90% RH for 1 month, (Aluminum box) in which only one side of the surface was openable and closable so that the inside of each side (six sides) was covered, and a temperature recorder was placed in the inside. The surface which can be opened and closed was allowed to stand in a thermostat kept at 5 ° C for 24 hours, then the surface which was opened and closed was closed and sealed together with the vacuum thermal insulating structure, The inside temperature was measured after 30 minutes, and the adiabatic effect was evaluated.

As shown in Table 1 above, the multilayer film obtained in the examples has excellent oxygen barrier properties and water vapor barrier properties, and the vacuum insulation structure using the multilayer film exhibits excellent heat insulation performance, The multilayered films obtained in Examples were inferior in oxygen barrier property and water vapor barrier property, and the heat insulating performance of the vacuum heat insulating structure using this multilayer film was also insufficient.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

The present application is based on Japanese Patent Application (Japanese Patent Application No. 2006-274595) filed on October 6, 2006, the content of which is incorporated herein by reference.

The multilayer film of the present invention is excellent in gas barrier property even in use under high humidity and has excellent heat insulating performance. The vacuum insulation structure of the present invention can be produced by using a multilayer film comprising a gas barrier film (A), a polyester film (B) and a polyolefin film (C) having a vapor permeability of 10 g / Since the heat insulating material is sealed and packaged, the vacuum property is maintained for a long period of time, and the gas barrier property and the heat insulating performance are excellent even under a high humidity. Therefore, it is possible to provide a refrigerator, a thermos bottle, And can be effectively used as a thermal insulation material for home appliances such as household electric appliances such as a water heater, a bathtub, a unit bath, a toilet, a housing system such as a floor heating, a solar roof, Of these, particularly, they can be suitably used particularly as a heat insulating material for a refrigerator.

Claims (8)

(A) / polyester film (B) composed of a vinyl alcohol film / multilayered film comprising a layered structure of a stretched polyolefin film (C) having a vapor permeability of 10 g / m 2 / day or less and a heat insulating material Wherein the multilayered film encapsulates the heat insulating material with the gas barrier film (A) inward. delete The vacuum insulation structure according to claim 1, wherein the gas barrier film (A) is an aluminum vapor deposited film. delete The vacuum insulation structure according to claim 1, wherein the vinyl alcohol film is a biaxially stretched polyvinyl alcohol film. The vacuum insulation structure according to any one of claims 1, 3 and 5, wherein the polyester film (B) is an aluminum deposited polyethylene terephthalate film. delete delete

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