JP2003049035A - Aqueous dispersion and vacuum deposition film laminated therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an aqueous dispersion capable of forming a resin coating layer which improves the humidity dependency of oxygen barrier property and exhibits high adhesivity to polyolefin-based materials. SOLUTION: The aqueous dispersion essentially contains (A) polyvinyl alcohol and (B) an ethylene/unsaturated carboxylic acid copolymer in the weight ratio A/B of (99:1) to (50:50) on a solid basis. The aqueous dispersion gives a laminated film which has good oxygen barrier property and high adhesivity to polyolefin-based materials by coating on the vapor deposition layer surface of a plastic film on a substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous dispersion containing polyvinyl alcohol and an ethylene / unsaturated carboxylic acid copolymer as essential components, and more specifically to an oxygen barrier property and a polyolefin-based material. It relates to an aqueous dispersion capable of forming a resin coating layer exhibiting excellent adhesiveness.

[0002]

2. Description of the Related Art Polyvinyl alcohol can be easily dissolved in water by controlling the degree of saponification and the molecular weight. By coating and drying this aqueous dispersion, it is possible to easily form a transparent coating film having an oxygen barrier property, so that the packaging film is coated with a polyvinyl alcohol-based material for the purpose of keeping the food fresh. Are increasing. Also, due to the recent increase in environmental problems, it has been attracting attention as a substitute material for polyvinylidene chloride coat.

On the other hand, there is a problem that the oxygen barrier property of polyvinyl alcohol is highly dependent on humidity. Specifically, since polyvinyl alcohol has a high hygroscopicity, there is a problem that its oxygen barrier property is extremely lowered when the humidity is high. As a solution to this problem, attempts have been made to reduce hygroscopicity and improve humidity dependency by using polyvinyl alcohol starting from a vinyl acetate / ethylene copolymer obtained by copolymerizing ethylene. However, the humidity dependence improved by this method is not always at a sufficient level.

In recent years, metal vapor-deposited films of aluminum or the like have been increasingly shunned for reasons such as environmental problems and obstacles to the use of metal detectors for removing foreign substances.

As a substitute material for such a metal vapor deposition film of aluminum or the like, a film obtained by vapor deposition of a ceramic such as silica or alumina is drawing attention. For example, JP-A-2-122924 and JP-A-3-71
No. 832 proposes a vapor deposition film using silica, and JP-A No. 10-140331 proposes a vapor deposition film using alumina. In addition, JP-A-3-2393
JP-A No. 4-191051 proposes a vapor-deposited film using alumina, and JP-A-3-191051 proposes a vapor deposition film using an oxide of silicon and aluminum in combination.

However, in many cases, the barrier property is not sufficient in practical use only with a film obtained by vapor-depositing ceramics,
Many methods for improving the oxygen barrier property have also been proposed and put to practical use in order to protect the ceramic vapor deposition layer. Specifically, polyvinyl alcohol having oxygen barrier properties is laminated as an oxygen barrier protection layer.

JP-A-11-310680 and JP-A-2
In JP-A-000-62108, it is described that by coating polyvinyl alcohol on the ceramic vapor-deposited surface, it is possible to further improve the barrier property and protect the ceramic vapor-deposited surface, so that cracking due to bending is less likely to occur. In addition, in Japanese Patent Application Laid-Open No. 11-165369, a ceramic vapor deposition surface is coated with an organic coating layer which is a composite of polyvinyl alcohol and an inorganic layered compound, and Japanese Patent Application Laid-Open Nos. 2001-64423 and 2001.
Japanese Patent Publication No. 145973 discloses that an oxygen barrier layer composed of polyvinyl alcohol and a metal alkoxide is coated on a ceramic vapor deposition surface via a primer.

The conventional packaging films including these prior arts are excellent in oxygen barrier property and also excellent in commercial value, but in addition to having humidity dependency, the oxygen barrier property including polyvinyl alcohol is adhesive. There is a problem that the adhesiveness with the agent and the adhesive resin layer is poor. When an adhesive or an adhesive resin layer is laminated on the oxygen barrier layer, delamination may occur at the interface with the oxygen barrier layer, which may cause a great trouble.

Further, from the viewpoint of laminating with other base material via an adhesive or an adhesive resin layer, the conventional method has the following various problems. That is, at present, as a laminating method, roughly speaking, a method of performing extrusion coating,
Examples thereof include a method of laminating films and a method of coating a coating agent such as emulsion.

When extrusion coating is performed, it is necessary to use an anchor coating agent because the oxygen barrier protective layer has poor adhesion, and it is necessary to select an anchor coating agent from many types. Moreover, the reality is that very few anchor coating agents have good adhesiveness. In addition, there is a limit to the coating thickness of the adhesive resin layer, and there is a problem that the greater the thickness, the greater the stress when being bent.

In the method of laminating films, it is more difficult to select an adhesive than in the above method, and the total thickness of the laminated film is further increased. On the other hand, when coating an emulsion or the like, it is difficult to select an emulsion from the viewpoint of adhesiveness, and an emulsion with good adhesiveness is sticky and generally causes severe blocking. Poor adhesion to materials, and lack of heat sealability.

As a result of intensive studies, the present inventors have found that a coating film obtained from an aqueous dispersion containing polyvinyl alcohol and an aqueous dispersion of an ethylenically unsaturated carboxylic acid copolymer as an essential component has an oxygen barrier property. Excellent, low humidity dependency, good adhesion to other polyolefin-based substrates, and when laminated on a ceramic vapor deposition film, it has a protective function for the vapor deposition layer, improves oxygen barrier properties and adheres as a packaging material. The inventors have found that a laminated vapor-deposited film having excellent adhesiveness to agents and adhesive resin layers can be obtained, and completed the present invention.

[0013]

Therefore, an object of the present invention is to provide an aqueous dispersion which provides a coating layer having excellent oxygen barrier properties, low humidity dependency, and excellent adhesion to other substrates. is there. Further, another object of the present invention is to coat the vapor-deposited surface of the ceramic vapor-deposited film with the above-mentioned aqueous dispersion, to have a protective function for the vapor-deposited layer, improve the oxygen barrier property, and to form an adhesive or an adhesive resin layer. It is to provide a laminated vapor deposition film having excellent adhesiveness.

[0014]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and comprises an aqueous dispersion of polyvinyl alcohol and an ethylene / unsaturated carboxylic acid copolymer as an essential component. There are important features in using an aqueous dispersion.

That is, according to the present invention, an aqueous dispersion of (A) polyvinyl alcohol and (B) ethylene / unsaturated carboxylic acid copolymer is used as an essential component, and the solid content of (A) :( B) There is provided an aqueous dispersion characterized in that the weight ratio is 99: 1 to 50:50.

Further, according to the present invention, there is provided the above aqueous dispersion further containing a metal alkoxide.

Further, according to the present invention, there is provided the above aqueous dispersion further containing a layered compound.

Further, according to the present invention, there is provided the above aqueous dispersion, wherein the dispersion medium of the ethylene / unsaturated carboxylic acid copolymer is ammonia or an alkali metal hydroxide.

According to the present invention, the dispersion has an unsaturated carboxylic acid content of 10 to 35% by weight and a melt flow rate (190 ° C., 2160 g load) of 50 to 20.
There is provided the above aqueous dispersion comprising an ethylene acrylic acid copolymer of 00 g / 10 minutes and ammonia.

Further, according to the present invention, the dispersion liquid of the ethylene / unsaturated carboxylic acid copolymer has a content of 2% in addition to the alkali metal.
There is provided the above aqueous dispersion containing a trivalent or trivalent metal.

Further, according to the present invention, there is provided the above aqueous dispersion, wherein the dispersion of the ethylene / unsaturated carboxylic acid copolymer contains zinc.

Further, according to the present invention, there is provided a laminated vapor deposition film characterized in that the above-mentioned aqueous dispersion is coated on the vapor deposition layer surface of a plastic film having a ceramic vapor deposition layer on a substrate.

Further, according to the present invention, there is provided the above-mentioned laminated vapor-deposited film, wherein the ceramic is silica or alumina.

Further, according to the present invention, there is provided a coating agent comprising the above aqueous dispersion.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The feature of the present invention is that an aqueous dispersion liquid of (A) polyvinyl alcohol and (B) ethylene / unsaturated carboxylic acid copolymer is an essential component, and the content ratio of both is expressed as solid content. The weight ratio of (A) :( B) is set to be 99: 1 to 50:50, whereby the humidity dependence of the oxygen barrier property of the film when this aqueous dispersion is coated on various substrates is determined. It is possible to provide a coating layer which can be improved and has excellent adhesiveness to an adhesive or an adhesive resin. Also, by coating this aqueous dispersion on the vapor deposition surface of a ceramic vapor deposition film, it has a protective function for the vapor deposition surface, improves the oxygen barrier property, and provides a laminated vapor deposition film with excellent adhesiveness to adhesives and adhesive resin layers. Obtainable.

<Polyvinyl alcohol> Polyvinyl alcohol can be obtained by a known method, and can be generally obtained by saponifying vinyl acetate. Saponification degree is 5
0% or more can be used, and particularly preferably 80% or more from the viewpoint of aqueous dispersion. Moreover, the thing which copolymerized ethylene in the ratio of 40% or less can also be used. The coating solution of polyvinyl alcohol may be prepared, for example, by supplying a predetermined amount of water and polyvinyl alcohol to a container equipped with a stirrer, or isopropyl alcohol with water, but at a temperature of about 50 ° C to 150 ° C. It can be easily obtained by stirring for about 10 minutes to 2 hours.

<Ethylene / Unsaturated Carboxylic Acid Copolymer>
As the ethylene / unsaturated carboxylic acid copolymer, ethylene and acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, etc. It is a copolymer with an unsaturated carboxylic acid, and among them, acrylic acid or methacrylic acid is preferable. In addition,
The ethylene-unsaturated carboxylic acid copolymer may contain any other monomer.

In the ethylene / unsaturated carboxylic acid copolymer, the ethylene component is 65 to 90% by weight, preferably 70 to 85% by weight, and the unsaturated carboxylic acid component is 10 to 35% by weight, preferably 15 to 30%. % By weight. The melt flow rate (MFR) of the ethylene / unsaturated carboxylic acid copolymer at 190 ° C. under a load of 2160 g is 30 to 2000 g / 10 min, preferably 60 to 1500 g / 10 min.

Monomers which may be optionally contained in the ethylene / unsaturated carboxylic acid copolymer include vinyl acetate, vinyl esters such as vinyl propionate, methyl acrylate, ethyl acrylate, acrylic acid. Isopropyl, n-butyl acrylate, isobutyl acrylate,
Unsaturated carboxylic acid esters such as isooctyl acrylate, methyl methacrylate, isobutyl methacrylate, dimethyl maleate, diethyl maleate, carbon monoxide,
Examples thereof include sulfur dioxide, and these monomers are preferably contained in a proportion of about 0 to 50% by weight. Such an ethylene / unsaturated carboxylic acid copolymer can be obtained by a method known per se, for example, radical polymerization under high temperature and high pressure.

The aqueous dispersion of the ethylene / unsaturated carboxylic acid copolymer in the present invention is a dispersion comprising the above copolymer and a dispersion medium such as ammonia, sodium hydroxide or potassium hydroxide, and the mixing ratio thereof. Is preferably a dispersion medium used in a proportion of 40 to 100% with respect to the number of moles of the carboxyl group of the ethylene / unsaturated carboxylic acid copolymer.

In order to produce an aqueous dispersion from an ethylene / unsaturated carboxylic acid copolymer and the above dispersion medium, for example, a container equipped with a stirrer is supplied with a predetermined amount of water and the above-mentioned two raw materials, and then 90 or It can be easily obtained by stirring at a temperature of about 150 ° C. for about 10 minutes to 2 hours. The aqueous dispersion liquid of the present invention has excellent stability and does not significantly change in particle size and viscosity even when stored for a long period of time.

In the present invention, the divalent or trivalent metal can be dispersed by adding it as an oxide together with the dispersion medium when producing the aqueous dispersion. In addition to the oxide, it can be introduced in the form of a metal carbonate or a metal sulfate. The mixing ratio can be introduced at a rate of 0 to 60% with respect to the number of moles of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer. However, it cannot be introduced without the combined use of a dispersion medium of ammonia or an alkali metal.

<Metal Alkoxide> To the aqueous dispersion of the present invention, one or more metal alkoxides or hydrolysates thereof may be added in order to further improve the oxygen barrier property. The metal alkoxide has the general formula M
(OR) (in the formula, M is a metal such as Si, Al and Ti, and R is a lower alkyl group such as a methyl group and an ethyl group), and specifically, tetraethoxysilane Preferred examples include triisopripoxyaluminum and the like.

<Layered Compound> Further, a layered compound, especially an inorganic layered compound may be added to the aqueous dispersion of the present invention in order to further improve the oxygen barrier property. The layered compound is dispersed in a layer form in an aqueous dispersion,
A resin component is introduced between the layers to enhance the oxygen barrier property, and examples thereof include clay minerals represented by the kaolinite group, the smectite group, the mica group and the like.
Specific examples include montmorillonite, hectorite, and saponite, which are inorganic layered compounds of the smectite group, and among them, montmorillonite is preferable.

<Ceramic Vapor Deposition Layer> As the ceramic, silica, alumina, zirconium oxide, titanium oxide, magnesium oxide and the like are used. Among them, silica and alumina are vapor deposition layers in terms of oxygen barrier property and substrate adhesion. Is preferably used as. The metal species used may be two or more in combination, and may be laminated with the same or different ceramics. The vapor deposition of ceramics on the substrate film is performed by, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion spraying method, a plasma chemical vapor deposition method, a thermochemical vapor deposition method, or a photochemical method. It is performed by a method known per se such as a chemical vapor deposition method (CVD method) such as a vapor phase growth method.

<Substrate Film> The substrate film constituting the laminated vapor deposition film of the present invention is not particularly limited as long as it is a plastic film capable of vapor-depositing ceramics, and polyethylene terephthalate, polyamide,
Examples of the film include polyamide imide, polyethylene, polypropylene, cellulose acetate, polycarbonate, polyvinyl chloride, and fluororesin film. Among them, polyethylene terephthalate, nylon, and polypropylene are preferable base film.

The thickness of the base material film is not particularly limited, and usually about 3 to 200 μm is used.
Further, the substrate film is preferably uniaxially stretched or biaxially stretched, and when using the one whose surface is surface-treated by corona discharge treatment or low-temperature plasma treatment, the vapor deposition of ceramic is more effective. Done.

<Coating of Evaporated Film with Aqueous Dispersion> Coating of an aqueous dispersion containing polyvinyl alcohol and an aqueous dispersion of an ethylene / unsaturated carboxylic acid copolymer as essential components on the surface of the ceramic vapor deposition is known per se. The coating method is appropriately selected. For example, a coating method using a roll coater, a bar coater, a sprayer, an air knife coater or a brush may be performed, or the vapor deposition film may be dipped in the aqueous dispersion. After coating, by heating and drying at a temperature of about 80 to 200 ° C. to evaporate the water content, a laminated vapor deposition film having a uniform coating layer can be obtained.

The thickness of the coating layer is not particularly limited, but is usually 0.1 to 20 μm, preferably 0.5 to 10 μm. The coating layer may be subjected to a crosslinking treatment by electron beam irradiation in order to improve water resistance and durability.

In the aqueous dispersion of the present invention, if necessary,
Various additives known per se can be added. Examples of such additives include polyhydric alcohols such as glycerin, ethylene glycol, polyethylene glycol, and polypropylene glycol, water-soluble epoxy resins, silane coupling agents, lower alcohols such as methanol, ethanol, normal propanol, and isopropanol, and ethylene glycol monomethyl. Ethers such as ether, propylene glycol monomethyl ether, propylene glycol diethyl ether, diethylene glycol monoethyl ether, propylene glycol monoethyl ether, esters such as propylene glycol monoacetate and ethylene glycol monoacetate, antioxidants, weathering stabilizers, UV rays Absorbent, antistatic agent, pigment, dye, antibacterial agent, lubricant, inorganic filler, antiblocking agent,
Adhesives and the like can be mentioned.

Further, the aqueous dispersion of the present invention can be mixed with an aqueous dispersion of another polymer as long as the effects of the present invention are not impaired. As such a polymer aqueous dispersion, polyvinyl acetate, ethylene-vinyl acetate copolymer,
Polyvinyl chloride, polyvinylidene chloride, water-soluble acrylic resin, acrylamide resin, methacrylamide resin, acrylonitrile resin, styrene-acrylic acid copolymer,
Water-soluble polyurethane resin, water-soluble styrene-maleic acid copolymer, styrene-butadiene copolymer, high-impact polystyrene resin, butadiene resin, polyester resin, acrylonitrile-butadiene copolymer, polyethylene resin, polyethylene oxide resin, propylene-ethylene Copolymer, maleic anhydride graft-propylene-
Examples thereof include ethylene copolymers, chlorinated polyethylene, chlorinated polypropylene, EPDM, phenolic resins, silicone resins, and epoxy resins, which may be used alone or in combination of two or more.

In the present invention, the problem that the oxygen barrier property of polyvinyl alcohol is highly dependent on humidity in the aqueous dispersion can be reduced by mixing the ethylene / unsaturated carboxylic acid copolymer. In addition, when it is used as a single layer of a packaging film, it has excellent adhesiveness with an adhesive or an adhesive resin layer, and when laminated on a ceramic vapor deposition film, it not only protects the ceramic vapor deposition layer, but also has an oxygen barrier property. It is possible to provide a laminated vapor-deposited film that can be improved, has reduced humidity dependency, and has excellent adhesiveness to an adhesive or an adhesive resin layer, and its technical significance is great.

[0043]

According to the present invention, the humidity dependence of oxygen barrier properties, which is a drawback of polyvinyl alcohol, is
It can be improved by mixing an unsaturated carboxylic acid copolymer,
When this is laminated on a ceramic vapor-deposited film, it is necessary to improve cracks, which are the drawbacks of a ceramic vapor-deposited film, and to eliminate the difficulty of adhesion with adhesives or adhesive resin layers, which is a problem when coating polyvinyl alcohol alone. You can The aqueous dispersion of the present invention can be suitably used as a coating for various base materials such as a polyamide film and a polypropylene film as well as a ceramic vapor deposition film.

[0044]

EXAMPLES The preferred embodiments of the present invention will be described below based on examples, but the present invention is not limited thereto.

<Sample> (1) Vapor Deposition Film A commercially available alumina vapor deposition film was used. Base material thickness: 1
2 μm (2) Polyvinyl alcohol Polyvinyl alcohol having a molecular weight of 500 and a saponification degree of 80 to 90% was used. ("PVA205" manufactured by Kuraray) <Method for preparing aqueous solution of polyvinyl alcohol> 300 ml
To the autoclave, add 64 g of polyvinyl alcohol and 256 g of ion-exchanged water, and heat at 80 ° C for 1 hour for 80 hours.
After stirring at 0 rpm, it was cooled to room temperature with tap water. The solid content was 20 wt%. (3) Aqueous dispersion of ethylene / unsaturated carboxylic acid copolymer Base polymer: ethylene / acrylic acid copolymer (AA
20 wt%, MFR300) Ethylene-acrylic acid copolymer (EAA) -Zn aqueous dispersion; solid content 21 wt%, ammonia dispersion (neutralization degree to acrylic acid 90%), ZnO addition (neutralization degree to acrylic acid 20) %); <Preparation method of EAA-Zn aqueous dispersion> To a 300 ml autoclave, the resin, ion-exchanged water, ammonia and zinc oxide shown in Table 1 were added, and the mixture was heated at 150 ° C for 1 hour to 80%.
After stirring at 0 rpm, it was cooled to room temperature with tap water.

[Table 1] (4) Mixing method The above two kinds of aqueous solutions were weighed in appropriate amounts, and after mixing, they were stirred with a stirrer to prepare a mixed solution. (5) Coating Method of Aqueous Dispersion Liquid Aqueous dispersion liquid was applied to a vapor deposition surface of a biaxially stretched PET film having a thickness of 50 μm and an alumina vapor deposition film by a bar coater
It was applied to a thickness of 0 μm and then dried at 150 ° C. for 3 minutes to obtain a laminated film.

<Experimental Method> (1) Measurement of oxygen permeability The oxygen permeability of a film obtained by laminating an aqueous dispersion on a biaxially stretched PET film having a thickness of 50 μm was measured by changing the humidity (MOCON method). (2) Polyolefin adhesion test Coating various emulsions with a thickness of 10 μm,
The coated surface and a PET film ((A) 20 μm / PE 20 μm / PET 12 μm) obtained by laminating ethylene / acrylic acid ester / methacrylic acid copolymer (A) were heat-sealed (180 ° C. × 1 s) and bonded with a width of 15 mm. The strength was measured.

Comparative Example 1 A stretched PET film was coated with a polyvinyl alcohol aqueous solution with a bar coater so as to have a thickness of 10 μm, and then heated at 150 ° C.
And dried for 30 minutes to form a coated film. Then, the humidity of the obtained film is 20% RH, 50
The oxygen permeability of% RH was measured. Alumina-deposited P
Polyvinyl alcohol was coated on the alumina-deposited surface of the ET film with a bar coater to a thickness of 10 μm.
The coated film was prepared by drying at 0 ° C for 3 minutes. Then, the obtained film and a film obtained by laminating an ethylene / methacrylic acid copolymer were heat-sealed (160 ° C. × 1 s), and the adhesive strength of 15 mm width was measured. The results are shown in Table 2.

Example 1 Instead of an aqueous polyvinyl alcohol solution, an aqueous polyvinyl alcohol solution and an EAA-Zn aqueous dispersion were mixed at 80:20.
The same procedure as in Comparative Example 1 was carried out except that the aqueous dispersion mixed in step 1 was used. The results are shown in Table 2.

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 3/34 C08K 3/34 5/057 5/057 5/5415 5/5415 C09D 5/00 C09D 5 / 00 Z 123/04 123/04 129/04 129/04 C23C 14/58 C23C 14/58 B // (C08L 29/04 C08L 23:08 23:08) F term (reference) 4F100 AA19B AA20B AH08A AK01C AK07 AK21A AK42 AK48 AK70A AL05A BA03 BA10A BA10C EH66B JA06A JD03 JK06 YY00A 4J002 BB082 BB092 BE021 DE058 DE159 DE249 DF008 DG049 DJ007 EC076 EX036 GH01 HA07 4A08 A11 PCC29 NA08A08 4K01 NA07A08 A11 NA07A04 A11 A07A04 A11 MAC29 NA08A08 NA12 A44A08 A11 A07A0 A4 A4 A4 AA4A11 A0 A4 A0 A4 A0 A4 A0 A4 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A1 A0 A4 A1 A0 A4 A1 A0 A4 A0 A4 A4 A0 A4 A0 of A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A4 A0 A of 4 A0 A4 0

Claims (10)

[Claims] 1. A polyvinyl alcohol (A) and (B)
An aqueous dispersion of an ethylene / unsaturated carboxylic acid copolymer is used as an essential component, and a solid content of (A) :( B) is 99:
An aqueous dispersion characterized in that it is from 1 to 50:50. 2. The aqueous dispersion according to claim 1, further comprising a metal alkoxide. 3. The aqueous dispersion according to claim 1, further comprising a layered compound. 4. The aqueous dispersion according to claim 1, wherein the dispersion medium of the ethylene / unsaturated carboxylic acid copolymer is ammonia or an alkali metal hydroxide. 5. The dispersion medium of the ethylene / unsaturated carboxylic acid copolymer has an unsaturated carboxylic acid content of 10 to 35% by weight.
And melt flow rate (190 ℃, 2160g load)
The aqueous dispersion according to claim 1, which comprises ethylene-acrylic acid copolymer having an amount of 50 to 2000 g / 10 minutes and ammonia. 6. The aqueous dispersion according to claim 1, wherein the dispersion of the ethylene / unsaturated carboxylic acid copolymer contains a divalent or trivalent metal in addition to the alkali metal. 7. The aqueous dispersion according to claim 1, wherein the dispersion of the ethylene / unsaturated carboxylic acid copolymer contains zinc. 8. A laminated vapor deposition film, characterized in that the aqueous dispersion according to any one of claims 1 to 7 is coated on the vapor deposition layer surface of a plastic film having a ceramic vapor deposition layer on a substrate. 9. The laminated vapor deposition film according to claim 8, wherein the ceramic is silica or alumina. 10. A coating agent comprising the aqueous dispersion according to any one of claims 1 to 7.