WO2003025058A1

WO2003025058A1 - Aqueous dispersion of ethylene/vinyl alcohol copolymer

Info

Publication number: WO2003025058A1
Application number: PCT/JP2002/009159
Authority: WO
Inventors: Eiichi Araki; Yuhei Funabiki; Keizo Michihata; Satoshi Hirofuji
Original assignee: Sumitomo Seika Chemicals Co., Ltd.; Kuraray Co., Ltd.
Priority date: 2001-09-12
Filing date: 2002-09-09
Publication date: 2003-03-27
Also published as: JPWO2003025058A1

Abstract

An aqueous ethylene/vinyl alcohol copolymer dispersion which has a high concentration and excellent long-term stability and gives a coating film having excellent gas-barrier properties. The aqueous ethylene/vinyl alcohol copolymer dispersion contains an ethylene/vinyl alcohol copolymer having an ethylene content of 15 to 65 mol% and a degree of saponification of 80 mol% or higher as a dispersed ingredient and further contains as a dispersion stabilizer an ethylene/α,ß-unsaturated carboxylic acid copolymer neutralized with a base.

Description

Specification

Aqueous dispersion of alcohol-based copolymer

Technical field

The present invention relates to aqueous dispersions. More specifically, the present invention relates to an aqueous dispersion of an ethylene nobule alcohol copolymer. Background art

Ethylene / butyl alcohol-based copolymer (hereinafter abbreviated as EVOH) obtained by saponification of ethylene / butyl acetate copolymer, etc. is extremely excellent in gas barrier properties such as oxygen, fragrance retention, oil resistance, and chemical resistance. Because of its superiority, it is suitably used for molded articles such as various films, sheets, and containers. It is also attracting attention as a material for protective coating on metal surfaces, paper, wood, etc. In particular, the gas barrier property is extremely superior to other resin films, and it is used for food packaging films, sheets, laminates, hollow containers, etc., which need to prevent oxidation of the contents or retain the scent. Very useful as a material.

In general, as a method of forming EVOH into a film, a sheet, or the like, a method of melt extrusion or injection molding of EVOH, a method of laminating an EVOH film, and the like are widely practiced. On the other hand, a method of applying and drying an EVOH solution or an aqueous dispersion has been proposed because a relatively thin film can be formed and a film having a complicated shape such as a hollow container can be easily formed. I have.

However, the EVOH solution increases viscosity at high concentrations and is difficult to use.The solution is an organic solvent such as dimethyl sulfoxide, or a mixed solvent of alcohol and water. There is a problem that the working environment is deteriorated due to volatilization, and equipment for collecting the organic solvent is required, which is economically disadvantageous. On the other hand, the method of applying an aqueous dispersion of EVOH is considered to be advantageous from the above-mentioned working environment and economic point of view because the dispersion medium is water, and is expected.

Examples of the EVOH aqueous dispersion include, for example, EVOH as a surfactant or polyethylene oxide, canolepoxy methinoresenorelose, hydroxyxetinole cellulose, polyester An EVOH aqueous dispersion emulsified and dispersed in the presence of a water-soluble polymer protective colloid such as rivul alcohol has been proposed (Japanese Patent Application Laid-Open Nos. 54-184184, 56-108). No. 6143). However, the dispersion stability and standing stability are insufficient, and the film-forming properties are poor, so that the obtained coating film has insufficient gas barrier properties.

Further, an EVOH aqueous dispersion in which EVOH is emulsified and dispersed by using EVOH having an ionic group as a dispersion stabilizer has been proposed (JP-A-4-225008, JP-A-5-908). No. 2009 publication). However, it is hard to say that the concentration of the aqueous dispersion is high and the film forming property is sufficient.

Furthermore, during the production process of the EVOH aqueous dispersion, the resin component is concentrated by a centrifugal separation method, and a high-concentration EVOH aqueous dispersion having a low viscosity and excellent storage stability (Japanese Patent Application Laid-Open No. 5-179001) ), Specific EVOH aqueous dispersions modified with peroxides and the like (Japanese Patent Application Laid-Open No. 7-118471) have been proposed. However, the aqueous dispersion obtained by the former method also has insufficient film-forming properties, and it is hard to say that the long-term storage stability is sufficient. In the latter method, a special treatment is required for the resin, the process is complicated, and the long-term storage stability is not sufficient. Summary of the Invention

An object of the present invention is to provide an aqueous dispersion of an ethylene-z-vinyl alcohol-based copolymer having high concentration, excellent long-term stability, and excellent gas barrier properties of a coating film obtained.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a specific ethylene / vinyl alcohol-based copolymer is used as a dispersoid, and a specific ethylene / bi,] 3-unsaturated carboxylic acid-based copolymer is used. It has been found that an aqueous dispersion of ethylene-Z-Biel-alcohol based on ethylene glycol as a dispersion stabilizer has excellent long-term stability at high concentration and excellent gas barrier properties of the obtained coating film. completed.

That is, the present invention is an ethylene content of 1 5-6 5 mol%, a saponification degree 8 0 mole ^_0/0 or more ethylene / Bulle alcohol copolymer as the dispersoid, as a dispersion stabilizer, is neutralized with a base Containing ethylene / _α , β-unsaturated carboxylic acid copolymers This is an aqueous dispersion of Z-vinyl alcohol copolymer. The ratio of the above ethylene / a,] 3-unsaturated carboxylic acid copolymer is ethylene z vinyl alcohol copolymer 1

It is preferable that the amount is 0.01 to 20 parts by weight based on 0.0 part by weight. The degree of neutralization of the above ethylene Za, J3-unsaturated carboxylic acid copolymer with a base is preferably 30 to 100 mol%. The content of the structural unit derived from a,] 3-unsaturated carboxylic acid in the ethylene / hi, J3-unsaturated carboxylic acid copolymer is preferably 5 to 30% by weight. The ethylene / α, 3-unsaturated carboxylic acid copolymer is an ethylene _α , | 3-unsaturated carboxylic acid copolymer or ethylene Ζα, β-unsaturated carboxylic acid Ζα, β monounsaturated carboxylic acid It is preferably an ester copolymer. The base is preferably an alkali metal hydroxide. The aqueous ethylene-butyl alcohol-based copolymer dispersion of the present invention preferably contains an inorganic filler. It is preferable that the inorganic filler is a salt of water-swellable furoic acid.

A laminate having a coating film formed from the aqueous dispersion of the ethylene / butyl alcohol-based copolymer of the present invention on at least one surface of a substrate is also one of the present invention. Detailed Disclosure of the Invention

The first feature of the present invention is that the use of an ethyleneno α, β monounsaturated carboxylic acid-based copolymer neutralized with a base as a dispersion stabilizer makes it possible to use a high concentration and agglomeration of particles during storage. This makes it possible to obtain an ethylene // butyl alcohol-based copolymer aqueous dispersion excellent in long-term stability without increasing the particle size or increasing the viscosity of the copolymer. Further, the second feature of the present invention is that, since the particle size of the ethylene butyl alcohol-based copolymer particles dispersed in the aqueous dispersion medium is small and the low-temperature film-forming property is good, the transparency is high and the gas barrier property is high. The advantage is that a coating film excellent in the above can be obtained.

The ethylene-vinyl alcohol copolymer (hereinafter, abbreviated as EVOH) used in the present invention is composed of ethylene, biel acetate, butyl formate, butyl propionate, vinyl benzoate, vinyl trifluoroacetate, and vinyl valinate. It can be obtained by copolymerization with a vinyl ester such as this and saponifying. Specifically, saponified ethylene / vinyl acetate copolymer, saponified ethylene / butyl formate copolymer, ethylene propylene Examples thereof include saponified vinyl onate copolymer, saponified ethylene / vinyl benzoate copolymer, saponified ethylene / vinyl trifluoroacetate copolymer, and saponified ethylene / vinyl vivalate copolymer. If necessary, a copolymerizable monomer other than ethylene and vinyl ester may be copolymerized in an amount of 5 mol% or less.

The ethylene content in the EVOH is 15-65 mol ⁰ /. , Preferably 20-5

5 mol%. When the ethylene content is less than 15 mol%, the stability of the obtained aqueous dispersion becomes insufficient. Also, if the ethylene content exceeds 65 mol ^_0/0, moth Subariya property becomes insufficient. The saponification degree is at least 80 mol%, preferably at least 95 mol%, more preferably at least 97 mol%. If the degree of saponification is less than 80 mol%, the gas barrier properties of the obtained coating film will be insufficient.

The higher the degree of polymerization of the EVOH, the more advantageous it is for coating and using as an aqueous dispersion, but it is usually about 400 to 5,000, preferably about 700 to 5,000. When the degree of polymerization is less than 400, the strength of the formed coating film is low, which is not preferable. Here, the degree of polymerization of EVOH can be determined from the intrinsic viscosity measured at 30 ° C. in a water-phenol mixed solvent (weight ratio: 15 to 85).

The ethylene / α, 3-unsaturated carboxylic acid-based copolymer used as the dispersion stabilizer in the present invention includes a copolymer of ethylene and α,] 3-unsaturated carboxylic acid or ethylene and a, J3- Copolymers of unsaturated carboxylic acids and α, -unsaturated carboxylic esters can be mentioned. That is, ethylene and α, β monounsaturated carboxylic acid copolymers of ethylene and α, β-unsaturated carboxylic acid with ethylene and random copolymers and block copolymers of ethylenic α,] 3-unsaturated carboxylic acid / α, unsaturated carboxylic acid ester with α, β-unsaturated ruponic acid esters. .

Examples of the α, | 3-unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Examples of the α,] 3-unsaturated carboxylic acid ester include methyl acrylate, Ethyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, monomethyl maleate, dimethyl methyl maleate, chloro Methyl tonate, methyl fumarate, methyl itaconate and the like can be mentioned.

Specific examples of the ethylene Za, j3-unsaturated carboxylic acid copolymer include: ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene z-crotonic acid copolymer, ethylene / maleic Acid copolymer, ethylene Z fumaric acid copolymer, ethylene / itaconic acid copolymer and the like. Among these, ethylene Z acrylic acid copolymer and ethylene Z methacrylic acid copolymer can be preferably used from the viewpoint of the dispersion stabilizing effect.

Specific examples of the ethylene-α, j3-unsaturated carboxylic acid / h, J3-unsaturated carboxylic acid ester copolymer include ethylene / methyl methyl acrylate / coacrylate, ethylene / acrylic acid / acrylic acid Ethyl copolymer, ethylene / meth'acrylic acid / methyl methacrylate copolymer, ethylene nocrotonic acid Z methyl crotonate copolymer, ethylene / methyl maleate maleate copolymer, ethylene / fumaric acid / fumaric acid Methyl copolymer, ethylene / itaconic acid methyl itaconate copolymer and the like can be mentioned. Among them, an ethylene / acrylic acid / ethyl acrylate copolymer can be preferably used from the viewpoint of a dispersion stabilizing effect. These ethylene Ζα,] 3-unsaturated carboxylic acid copolymers may be used alone or in combination of two or more.

The content of the structural unit derived from _α , / 3-unsaturated carboxylic acid in the ethylene / tri-, unsaturated carboxylic acid-based copolymer is not particularly limited, but is usually 5 to 30% by weight. , Preferably 15 to 25 weight. / ₀ . _When the content of the constituent unit derived from _α ,] 3-unsaturated carboxylic acid is less than 5% by weight, the dispersion stabilizing effect may be reduced. If the content of the constituent unit derived from α, 3-unsaturated carboxylic acid exceeds 30% by weight, the water resistance and gas barrier property of the obtained coating film may be impaired.

The amount of the ethyleneno <<, / 3-unsaturated carboxylic acid copolymer used is not particularly limited. However, it is usually 0.01 to 20 parts by weight, preferably 0.05 to 5 parts by weight, based on 100 parts by weight of EVOH. If the amount of the ethylene-α, / 3-unsaturated carboxylic acid copolymer is less than 0.01 parts by weight, the dispersing effect may not be expected. When the amount of the ethylene-α,] 3-unsaturated carboxylic acid-based copolymer exceeds 20 parts by weight, the copolymer is easily dispersed, but may impair the gas barrier properties and water resistance of the obtained coating film. There is.

The degree of neutralization of the ethylene Za, β-unsaturated carboxylic acid-based copolymer with a base is not particularly limited. 1 0 0 mol% have been neutralized, preferably 4 0-1 00 mol%, more preferably 5 0-1 0 0 mole ^_0/0. If the degree of neutralization of the 3 0 mole ^_0/0 less than, for reduced properties as a dispersion stabilizer, which may be obtained with excellent stability EVOH aqueous dispersions difficult.

Examples of the base include, but are not particularly limited to, usually, alkali metal hydroxides such as sodium hydroxide, hydroxylic lime, ammonia, and organic amines. Among them, alkali metal hydroxides are suitably used from the viewpoint of the stability of the obtained EVOH aqueous dispersion.

The method for producing the EVOH aqueous dispersion of the present invention is not particularly limited, and a known method can be used. For example, a method of dissolving EVOH and a dispersion stabilizer in a solvent, then cooling and precipitating and dispersing, and then removing the solvent; heating the EVOH and the dispersion stabilizer to a solvent that dissolves at high temperatures but becomes insoluble at low temperatures After dissolving and then cooling the solution to precipitate and disperse, replacing the solvent with water; contacting the solution of EVOH and the dispersion stabilizer with a poor solvent or cooling to remove precipitated particles. Separately, there is a method of dispersing the obtained particles in water.

In the present invention, a method in which EVOH is dissolved in a solvent, then cooled, precipitated and dispersed, and then the solvent is removed is suitably used. More specifically, an ethylene / α, β-unsaturated carboxylic acid copolymer neutralized with EVOH and a dispersion stabilizer base is dissolved in a mixed solvent at 50 to 75 ° C. with stirring. Then, the mixture is cooled to −10 to 30 ° C., and the EVOH particles are precipitated and dispersed to have a weight average particle size of 1 m or less, preferably 0.5 μππι or less, more preferably 0.3 μππι or less. , Add water as needed, The solvent is removed under normal pressure or reduced pressure, and an EVOH aqueous dispersion having a desired concentration can be obtained.

Examples of the solvent for dissolving the EVOH include water, monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol; dihydric alcohols such as ethylene glycol and propylene glycol; glycerin and the like. Phenols such as phenol and cresonole; amines such as ethylenediamine and trimethylenediamine; and mixed solvents such as dimethyl sulfoxide, dimethylacetamide and N-methylpyrrolidone. Among them, a mixed solvent of water Z alcohol, particularly water / methyl alcohol, water / ethyl alcohol, water / n-propyl alcohol, water / isopropyl alcohol, and the like are preferably used.

The concentration of EVOH in the EVOH aqueous dispersion is 15% by weight or more, preferably 20% by weight. / ₀ or more, more preferably 25% by weight or more. The upper limit of the concentration is not particularly limited. However, if the concentration is too high, the storage stability of the aqueous dispersion may become poor and the viscosity may increase. Therefore, the concentration is usually 50% by weight or less, preferably 4% by weight. 0% by weight or less.

If necessary, ordinary surfactants and protective colloids can be added to the EVOH aqueous dispersion of the present invention as long as the object of the present invention is not hindered. Further, an aqueous dispersion of another resin, a stabilizer against light or heat, a pigment, a lubricant, a fungicide, a film-forming aid, or the like can be added.

By adding an inorganic filler to the thus obtained EV〇H aqueous dispersion of the present invention, it is possible to obtain an EVOH aqueous dispersion which gives a coating film having even better gas barrier properties under high humidity. .

Examples of the inorganic filler include a salt of water-swellable firocheic acid, talc, myriki, cres, calcium carbonate, and gypsum. Above all, a salt of water-swellable phyllokeic acid is preferably used, and specific examples thereof include smectites such as montmorillonite, beidelite, nontronite, savonite, hectolite, sauconite, and stibnite. And the like. Among them Smectites, especially montmoring mouths, are preferably used.

The amount of the inorganic filler added is usually 0.0 with respect to 100 parts by weight of E VOH.

It is 1 to 20 parts by weight, preferably 0.5 to 5 parts by weight. The amount of inorganic filler added

If the amount is less than 0.01 part by weight, the effect of improving gas barrier properties may not be expected. 'If the amount of the inorganic filler exceeds 20 parts by weight, the effect of improving the gas barrier property can be expected, but the viscosity of the aqueous dispersion becomes too high, which may impair the stability of the aqueous dispersion.

The method of adding the inorganic filler is not particularly limited. For example, a method of mixing an aqueous dispersion of the inorganic filler and the aqueous EV◦H dispersion under stirring, and a method of producing the aqueous EV◦H dispersion when mixing. Examples include a method of adding an inorganic filler to an EVOH solution. In the present invention, a coating film can be formed on a substrate by applying the EVOH aqueous dispersion on a substrate and performing a dry heat treatment. The thickness of the EVOH coating film is usually 0.5 to 15; um, preferably 1 to: L0; uin, and more preferably 2 to 6 μπι. If the thickness of the coating film is less than 0.5 μπι, there is a concern that the gas barrier property may be deteriorated due to pinholes and the like, and even if the coating film exceeds 15 m, it is not economical.

Examples of the substrate include rolled or biaxially stretched films of high-density polyethylene, polypropylene, nylon, polyester, polycarbonate, polychloride bilidene, and polystyrene. Substrates other than the above-mentioned films include various molded products such as sheets, cups and bottles, paper, nonwoven fabric, woven fabric, fiber aggregates such as fiberglass casings, inorganic materials such as cement, metals, and wallpaper made of polyvinyl chloride resin. And photographic printing paper.

The method for applying the EVOH aqueous dispersion of the present invention to a substrate is not particularly limited, and includes a casting head method, a roll coating method, an air knife coating method, a gravure opening single coating method, a doctor low coating method, and a doctor knife coating method. Known coating methods such as curtain flow coating, spraying, dipping, and brushing can be employed. Examples of the method for drying and heat-treating the substrate coated with the EVOH aqueous dispersion by the above method include a dry heat treatment method such as an infrared irradiation method and a hot air drying method. The temperature for the drying and heat treatment is 30 to 230 ° C, preferably 50 to 230 ° C, and more preferably 80 to 230 ° C. The drying and heat treatment time varies depending on the temperature, but is usually 5 seconds to 10 minutes, preferably 1 to 5 minutes.

Further, the surface of the base material may be previously anchor-coated with an adhesive. The adhesive is not particularly limited, and examples thereof include polyurethane-based and polyester-based adhesives. In addition, surface treatment such as corona discharge treatment, sputtering treatment, high frequency treatment, flame treatment, chromic acid treatment, and solvent etching treatment can be applied to the substrate surface.

Further, another resin layer may be laminated by a conventionally known method on the laminate comprising the substrate and the coating film obtained from the aqueous EVOH dispersion of the present invention obtained by the above method, to form a multilayer. it can. Examples of the lamination method include an extrusion lamination method and a dry lamination method. .

In laminating these layers, an ordinary method of laminating an adhesive resin layer between layers can be adopted. The adhesive resin is not particularly limited as long as it does not cause delamination in a practical stage, and examples thereof include, but are not limited to, a modified olefin polymer containing a hydroxyl group; and a modified olefin polymer containing a glycidyl group. Copolymer; Modified olefin polymer containing alkoxysilane group; Polyester resin containing polyhydric carboxylic acid, polyhydric alcohol, or hydroxycarboxylic acid as a constituent component.

Specifically, carboxyl groups such as maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene z-ethyl acrylate copolymer, and maleic anhydride-grafted ethylene Z-vinyl acetate copolymer, etc. Modified olefin polymer containing glycidyl group, such as glycidyl-modified polyethylene, glycidyl-modified polypropylene, glycidyl-modified ethylene / ethyl acrylate copolymer, and glycidyl-modified ethylene / vinyl acetate copolymer Polymer; alkoxysilane-modified polyethylene, Al Modified olefin polymers containing an alkoxysilane group, such as coxysilane-modified polypropylene and alkoxysilane-modified ethylene / vinyl acetate copolymers, can be mentioned.

The laminate obtained in this way is extremely suitable for containers such as bags, cups, tubes, trays, bottles, etc. composed of laminates of films, sheets, etc., for general food packaging, pharmaceutical packaging, and retort food packaging. It is. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example 1)

To the ethylene Z acrylic acid copolymer (acrylic acid content 21% by weight) was added water and sodium hydroxide equivalent to 60 mol% of neutralized acrylic acid 95. C for 4 hours to obtain a partially neutralized aqueous solution of an ethylenenoacrylic acid copolymer having a concentration of 25% by weight.

Ethylene acetate Bulle copolymer saponified as dispersoid (ethylene content 3 2 molar ^_0/0, a saponification degree 9 9.5 mole ^_0/0, the degree of polymerization 1 0 0 0) 5 parts by weight of methyl alcohol 5 7 wt Parts, 36 parts by weight of water and as dispersion stabilizer obtained above:

2 parts by weight of an aqueous solution of a acrylic acid copolymer was dissolved by heating at 67 ° C.

The resulting solution was cooled to 5 ° C under stirring to precipitate and disperse particles.

Thus, an alcohol-based copolymer dispersion was obtained. Subsequently, methyl alcohol in the obtained ethylene / vinyl alcohol-based copolymer dispersion was distilled off, and an aqueous dispersion of ethylene Z-butyl alcohol-based copolymer having an average particle diameter of 0.15 μm and a concentration of 30% by weight was removed. The obtained aqueous dispersion of ethylene butyl alcohol-based copolymer was allowed to stand at 40 ° C. for 180 days, but no aggregation was observed and the stability was good.

(Example 2)

In Example 1, the ethylene Z content 27 mol%, degree of saponification 99.5 mol. /. An aqueous dispersion of an ethylene / vinyl alcohol copolymer having an average particle size of 0.16 μm and a concentration of 25% by weight was prepared in the same manner as in Example 1 except that the polymerization degree was changed to 100. I got

The obtained aqueous dispersion of ethylene Z-Butyl alcohol-based copolymer was left at 40 ° C. for 180 days, but no aggregation was observed and the stability was good.

(Example 3)

Example 1 was repeated, except that the ethylene / acrylic acid copolymer was changed to an ethylene / acrylic acid Z-ethyl acrylate copolymer (acrylic acid content: 21% by weight). An aqueous ethylene / vinyl alcohol copolymer dispersion having a diameter of 0.14 / z ni and a concentration of 27% by weight was obtained.

The obtained aqueous dispersion of ethylene / vinyl alcohol copolymer was left at 180 ° C. for 1803, but no aggregation was observed and the stability was good. (Example 4)

Example 1 was repeated, except that the ethylene Z acrylic acid copolymer was changed to an ethylene Z methacrylic acid co-copolymer (methacrylic acid content: 21% by weight). The average particle diameter was 0.1. An aqueous ethylene-vinyl alcohol-based copolymer dispersion having a concentration of 7 μπι and a concentration of 29% by weight was obtained.

The obtained aqueous dispersion of ethylenenovinyl alcohol copolymer was left at 40 ° C. for 180 days, but no aggregation was observed and the stability was good.

(Example 5)

100 parts by weight of the aqueous ethylene-vinyl alcohol-based copolymer dispersion obtained in Example 1 and 10 parts by weight of a 1% by weight colloid solution of montmorillonite (trade name "Kunipia F" of Kunimine Industry Co., Ltd.) After mixing, the mixture was diluted with water to obtain an aqueous dispersion of ethylene Z vinyl alcohol-based copolymer having a concentration of 25% by weight.

The obtained aqueous dispersion of ethylene / vinyl alcohol copolymer was cooled at 180 ° C. to 180 ° C. After standing for a day, no aggregation was observed and the stability was good. (Example 6)

Example 1 was repeated except that 57 parts by weight of methyl alcohol and 36 parts by weight of water were changed to 38 parts by weight of isopropyl alcohol and 55 parts by weight of water. An aqueous ethylene / vinyl alcohol copolymer dispersion having a concentration of 0.17 μιη and a concentration of 30% by weight was obtained.

The obtained aqueous dispersion of ethylene / vinyl alcohol copolymer was allowed to stand at 40 ° C. for 180 days, but no aggregation was observed and the stability was good.

(Example 7)

Water and 100 mol of acrylic acid in ethylene Z acrylic acid copolymer (acrylic acid content: 21% by weight). /. Sodium hydroxide equivalent to the neutralization was added and dissolved at 95 ° C for 4 hours to obtain a neutralized aqueous solution of an ethylene Z acrylic acid copolymer having a concentration of 25% by weight.

Ethylene / acetate Bulle copolymer saponified as dispersoid (ethylene content 3 2 molar ^_0/0, a saponification degree 9 9.5 mole ^_0/0, the degree of polymerization 1 0 0 0) 5 parts by weight of isopropyl alcohol 3 8 parts by weight and 56.6 parts by weight of water 0.4 part by weight of the aqueous solution of the ethylene / acrylic acid copolymer obtained above as a dispersion stabilizer was dissolved by heating at 67 ° C. The resulting solution was cooled to 5 ° C. with stirring to precipitate and disperse the particles to obtain an ethylene / vinyl alcohol-based copolymer dispersion. Next, isopropyl alcohol in the obtained ethylene / vinyl alcohol-based copolymer dispersion was distilled off, and the average particle diameter was 0.20 m and the concentration was 31 wt. /. Thus, an aqueous dispersion of an ethylene / vinyl alcohol copolymer was obtained.

The obtained aqueous dispersion of ethylene Z vinyl alcohol copolymer was left at 40 ° C. for 180 days, but no aggregation was observed and the stability was good.

(Example 8)

Aqueous dispersion of ethylene / butyl alcohol-based copolymer obtained in Example 7 100 4 parts by weight of Montmorillonite (trade name "Kunipia F" of Kunimine Industry Co., Ltd.). / ₀ after mixing the colloidal solution 23 parts by weight, it was diluted with water to give a concentration of 2 '6 by weight percent Echiren / vinyl alcohol copolymer aqueous dispersion.

(Example 9)

Apply a urethane anchor coating agent (trade name “AD 335 A / CAT 10” of Toyo Morton Co., Ltd.) to the corona-treated surface of a biaxially stretched polypropylene film (Toseguchi Co., Ltd., film thickness 20 μπι). Next, the ethylene / vinyl alcohol copolymer aqueous dispersion obtained in Example 1 was applied by an air knife coating method, dried at 110 ° C. for 5 minutes, and heat-treated, to obtain a laminate (EVOH layer thickness) of the present invention. 2 μπι) was obtained.Oxygen barrier property of the obtained laminate was measured using OX-TRAN10 / 5OA of Modern Control at 20 ° C, relative humidity of 0% and 85%. As a result, the oxygen permeation amounts were 2.3 cc / m ² · day · a tm and 12 cc / m ² ■ day ■ a tm, respectively. Usually, when the oxygen permeation amount is 20 cc / m ² ■ day · a tm or less, it can be judged that the oxygen barrier property is excellent.

(Example 10)

A laminate was obtained in the same manner as in Example 9, except that the aqueous ethylene / vinyl alcohol copolymer dispersion obtained in Example 2 was used. The obtained laminate was evaluated for oxygen barrier property in the same manner as in Example 9, and the oxygen permeation amount was 1.8 cc / m ² · day. ■ atm _s 10 c cZm ² 'day' a tm.

(Example 11)

A laminate was obtained in the same manner as in Example 9, except that the aqueous dispersion of the ethylene Z vinyl alcohol copolymer obtained in Example 3 was used. Same as Example 9 for the obtained laminate. When the oxygen barrier properties were evaluated in the same manner, the oxygen permeation amounts were 1. S cc / m ² · day · atm _N丄 1 cc / m ² · day · atm, respectively.

(Example 12)

A laminate was obtained in the same manner as in Example 9 except that the aqueous dispersion of ethylenenobutyl alcohol-based copolymer obtained in Example 4 was used. The obtained laminate was evaluated for oxygen barrier properties in the same manner as in Example 9, and the oxygen permeation amount was 1.9 cc / m ² · day ■ at 9 ccm ”at 'day' atm 7

(Example 13)

A laminate was obtained in the same manner as in Example 9, except that the aqueous dispersion of ethylene Z butyl alcohol-based copolymer obtained in Example 5 was used. The obtained laminate was evaluated for oxygen barrier property in the same manner as in Example 9, and the oxygen permeation amount was 1.3 cc / m ² ■ day · at 8. Ice / m ² · day · It was atm. From the observation of the surface and the cross section of the coating film by an optical microscope (magnification: 100 times), no aggregates or local aggregates of montmorillonite were observed.

(Example 14)

Using the aqueous ethylene / vinyl alcohol copolymer dispersion obtained in Example 6, the same procedure as in Example 9 was carried out to obtain a laminate. When the obtained laminate was evaluated for oxygen barrier property in the same manner as in Example 9, the oxygen permeation amount was 2.4 cc / m ² -day · atm and 12 cc / m ² , respectively. day ■ a tm.

(Example 15)

A laminate was obtained in the same manner as in Example 9, except that the aqueous ethylene-vinyl alcohol-based copolymer dispersion obtained in Example 7 was used. When the obtained laminate was evaluated for oxygen barrier properties in the same manner as in Example 9, the oxygen permeation amount was 1.9 cc / m ² 'day' atm ヽ 9 cc / m "-day- a tm 7 (Example 16)

A laminate was obtained in the same manner as in Example 9 using the aqueous dispersion of ethylene Z butyl alcohol-based copolymer obtained in Example 8. When the obtained laminate was evaluated for oxygen barrier property in the same manner as in Example 9, the oxygen permeation amount was 1.2 _CC Zm ² · day ■ atm _N 7.8 cc / m ² · day · It was atm. From the observation of the surface and the cross section of the coating film with an optical microscope (magnification: 100 times), no aggregates or local aggregates of montmorillonite were found. (Example 17)

A biaxially stretched polyethylene terephthalate film (Diafoil Hext Co., Ltd., 12 m thick) is coated with a urethane anchor coating agent (trade name "AD 335 A / CAT 10" of Toyo Morton Co., Ltd.) on the surface. Then, the aqueous dispersion of the ethylene / vinyl alcohol copolymer obtained in Example 8 was applied by an air knife coating method, dried at 210 ° C. for 5 minutes, and heat-treated to obtain a laminate of the present invention (EVOH A layer thickness of 2 μm) was obtained. The obtained laminate was evaluated for oxygen barrier properties in the same manner as in Example 9, and the oxygen permeation amount was 0.4 cc / m ² .day.a tm and ^2.5 cc / m ² ■ day, respectively. · A In addition, from an optical microscope observation (magnification: 100 times) of the surface and cross section of the coating film, no aggregates or localized aggregates of montmorillonite were found.

(Comparative Example 1)

When the same operation as in Example 1 was performed except that the ethylene / acrylic acid copolymer partially neutralized aqueous liquid was not added in Example 1, the precipitated particles aggregated when cooled to 5 ° C. However, an aqueous dispersion of an ethylene novinyl alcohol copolymer could not be obtained.

(Comparative Example 2) The same operation as in Example 2 was performed except that the aqueous solution of the ethylene / acrylic acid copolymer partially neutralized was not used in Example 2, but when cooled to 5 ° C, precipitated particles aggregated. However, an aqueous dispersion of an ethylene novinyl alcohol copolymer could not be obtained. Industrial applicability

The aqueous ethylene / butyl alcohol copolymer dispersion of the present invention contains an ethylene / bier alcohol copolymer having an ethylene content of 15 to 65 mol% and a saponification degree of 80 mol% or more, and a dispersion stabilizer. Excellent stability during storage because it contains ethylene / tri-unsaturated carboxylic acid copolymer neutralized with a base. Further, the coating film obtained from the aqueous dispersion of the ethylene Z-butyl alcohol-based copolymer of the present invention has excellent oxygen barrier properties and is of high industrial value.

Claims

The scope of the claims

1. Ethylene content 15-65 mol. /. An ethylene / butyl alcohol copolymer having a degree of saponification of 80 mol% or more was used as a dispersoid, and an ethylene // _α , / 3-unsaturated carboxylic acid copolymer neutralized with a base was used as a dispersion stabilizer. , An ethylene-dibutyl alcohol-based copolymer aqueous dispersion.

2. The ratio of ethylene / α, | 3-unsaturated carboxylic acid-based copolymer is 0.01 to 20 parts by weight based on 100 parts by weight of ethylene / vinyl alcohol-based copolymer. 2. The aqueous dispersion of an ethylene / vinyl alcohol copolymer according to claim 1.

3. The degree of neutralization of the ethylene Ζα,) 3-unsaturated carboxylic acid copolymer with a base is 3

0-1 00 mole ^_0/0 ethylene Ζ Bierua alcohol copolymer aqueous dispersion according to the first or second term claims is.

4. The content of the structural unit derived from the _α , j3-unsaturated carboxylic acid in the ethylene / _α , —unsaturated carboxylic acid-based copolymer is from 5 to 30% by weight. 4. The aqueous dispersion of an ethylene / butyl alcohol-based copolymer according to any one of the items 3 to 3.

5. If the ethylene / j-unsaturated carboxylic acid copolymer is ethylene /, β-unsaturated carboxylic acid copolymer or ethylene / α, monounsaturated carboxylic acid α, j3-unsaturated carboxylic acid ester The aqueous dispersion of an ethylene / vinyl alcohol copolymer according to any one of claims 1 to 4, which is a polymer.

6. The aqueous dispersion of an ethylene Z vinyl alcohol copolymer according to any one of claims 1 to 5, wherein the base is an alkali metal hydroxide.

7. The etch according to any one of claims 1 to 6, including an inorganic filler. Nyl alcohol copolymer aqueous dispersion.

8. The aqueous dispersion of an ethylene / butyl alcohol-based copolymer according to claim 7, wherein the inorganic filler is a salt of a water-swellable formic acid.

9. A laminate having a coating film formed from the aqueous ethylene / z-vinyl alcohol-based copolymer dispersion according to any one of claims 1 to 8 on at least one surface of a substrate. .