JP3426635B2 - Modified ethylene-vinyl alcohol copolymer, dispersion stabilizer and aqueous dispersion - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dispersion stabilizer and an aqueous dispersion, and in particular, by heat-treating the film,
The present invention relates to an ethylene-vinyl alcohol copolymer capable of increasing the strength of a film.

[0002]

2. Description of the Related Art Ethylene-vinyl ester copolymers, particularly ethylene-vinyl alcohol copolymers (hereinafter abbreviated as EVOH) obtained by saponifying ethylene-vinyl acetate copolymers, have a gas barrier property against oxygen, etc. and oil resistance. Due to its excellent chemical resistance, it can be used as a packaging material, plastic molding,
It has attracted attention as a material for protective coating of metal surfaces, paper, wood and the like.

Particularly, high gas barrier properties are required for food packaging films, sheets, laminates, hollow containers and the like, which are required to prevent oxidation of contents or to retain scent. Further, for vinyl chloride wallpaper, vinyl chloride leather, sheets and the like made of soft vinyl chloride, a coating agent for preventing bleeding of a plasticizer is required. Therefore, it is widely practiced to provide the EVOH having excellent gas barrier property, aroma retaining property, and oil / chemical resistance in the inner layer, the outer layer or the intermediate layer to highly satisfy these required performances.

Generally, as a method of forming an EVOH layer, a method by melt extrusion or injection molding, a method of laminating an EVOH film, etc. are widely practiced.
On the other hand, a method of applying a solution of EVOH or an aqueous dispersion and drying it has been proposed. This method attracts attention because it is possible to form a film having a relatively thin film thickness and that a film having a complicated shape such as a hollow container can be easily formed.

However, in the method of applying a solution of EVOH, it is basically difficult to use a solution having a high concentration due to its high viscosity, and the solvent is an organic solvent such as dimethyl sulfoxide or a mixed solvent of a large amount of alcohol and water. In the process of forming a film, there is a problem in that the work environment is deteriorated due to volatilization of the organic solvent and an apparatus for recovering the organic solvent is required, which is economically disadvantageous. On the other hand, the method of applying an aqueous dispersion of EVOH is expected to be advantageous because it is an aqueous solvent and is considered to be advantageous from the viewpoint of the working environment and economy.

As an aqueous dispersion of EVOH, a conventional E
Japanese Patent Laid-Open No. 54-10184 discloses that VOH is emulsified and dispersed in the presence of a surfactant or a polymer colloid such as polyethylene oxide, carboxymethyl cellulose, hydroxyethyl cellulose and polyvinyl alcohol.
4, proposed in JP-A-56-61430. However, according to the study by the present inventors, the aqueous dispersion of EVOH obtained by these known methods has insufficient dispersion stability and insufficient film strength, and is difficult to be practically used for coating.

Further, in JP-A-54-101844, a so-called random copolymer obtained by terpolymerizing a carboxyl group-containing monomer such as acrylic acid or maleic anhydride with ethylene and vinyl acetate and saponifying the same was obtained. It has been shown that EVOH itself of a random copolymer is dispersed with a surfactant as a dispersion stabilizer.

However, according to the study by the present inventors, EVOH by simple ternary random copolymerization did not show improvement in emulsion dispersion stability, and practical emulsion dispersion was not obtained. Among them, when acrylic acid having an ionic group is copolymerized, the emulsion dispersion stability is improved by the ionic group, but since the ionic group is contained at random, emulsification is required unless the content is increased. Dispersion stability cannot be achieved sufficiently, and if so, the EVOH structure is greatly disturbed and the crystallinity is reduced, and the gas barrier performance is greatly reduced, which is not practical.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a dispersion stabilizer of EVOH having an ionic group and containing a crosslinkable group, and the dispersion stability is remarkably improved by using the EVOH dispersion stabilizer. To provide an EVOH-based aqueous dispersion having excellent strength.

[0010]

The above-mentioned object is to provide a sulfonic acid and its salt, a sulfuric ester and its dispersion stabilizer.
Salt, phosphoric acid and its salt, amine and its salt, quaternary
Ammonium salt, phosphonium salt and sulfonium
It has at least one ionic group selected from the group consisting of salts , and has 0.0005 to 5 mol% of a crosslinkable group, an ethylene content of 10 to 70 mol% and a saponification degree of 80 mol.
This is achieved by dispersing EVOH, which is a dispersoid, in water with greater than or equal to % modified EVOH.

The most important feature of the present invention is that the EVOH-based aqueous dispersion is significantly improved in stability during storage or use and is excellent in dispersion stability, and the EVOH-based aqueous dispersion is coated by heat treatment after coating. Is to increase the strength of. A small particle size is also an important feature because it has a small particle size and is excellent in dispersion stability, and there is almost no significant increase in particle size due to agglomeration of particles during storage or use.

The dispersion stabilizer used in the present invention has an ionic group and contains 0.0005 to 5 mol% of a crosslinkable group, an ethylene content of 10 to 70 mol% and a saponification degree of 80.
The modified ethylene-vinyl ester copolymer saponification product (hereinafter abbreviated as modified EVOH) is used in an amount of mol% or more, and the production method thereof is not limited.

In the present invention, the ionic group is a group exhibiting ionicity (anionic property, cationic property, amphoteric property) in water, and a sulfonic acid group or a salt thereof , an ammonium group and the like are preferably exemplified. The ionic group may be one type or two or more types.

As the anionic group, sulfonic acid, sulfonic acid salt, sulfuric acid ester, sulfuric acid ester salt, phosphoric acid, phosphoric acid salt
And the like , and these acids and bases may be contained at the same time. In that the dispersion stabilizing effect is excellent, especially sulfonic acid or salt is desired.

Examples of the cationic group include groups such as amines or salts thereof, quaternary ammonium salts, phosphonium salts and sulfonium salts. Particularly, a quaternary ammonium salt is preferable because it has a large dispersion stabilizing effect. Examples of the amphoteric group include amino sulfonate (sulfobetaine type) and amino sulfate ester salt (sulfate betaine type).

The content of the ionic group is appropriately selected within a range having a dispersion stabilizing effect, but from the viewpoint of the dispersion stabilizing effect, it is 0.05 to 50 relative to the EVOH component unit in the modified EVOH.
% Is desirable. More preferably 0.1 to 30 mol%,
Especially 0.2 to 15 mol%, more preferably 0.2 to 10 mol%
Is desirable. If it is less than 0.05 mol%, the dispersion stabilizing effect is small, and if it exceeds 50 mol%, an aqueous dispersion is applied.
The water resistance and gas barrier property of the film obtained by drying become poor, which is not preferable.

In the present invention, the crosslinkable group is a group which forms a crosslinked structure by heating and / or a crosslinking catalyst,
For introducing the crosslinkable group, one kind or two or more kinds selected from olefinic unsaturated monomer compounds having crosslinkability can be preferably used. Particularly, one or more compounds selected from the compounds represented by the following general formula are preferably used.

[0018]

[Chemical 1]

Here, n is an integer of 0 to 1, and m is 0.
Is an integer of 2 to ¹ , and R ¹ has 1 to 10 carbon atoms, preferably charcoal.
Alkyl groups having 1 to 5 primes , aryl groups or alkyl groups having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms
And R ² is a linear or branched alkoxyl group having 1 to 40 carbon atoms, and the alkoxyl group may have a substituent containing oxygen.

[0020]

[Chemical 2]

Here, R ³ is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, and R ⁴ is a linear or branched alkyl group having 1 to 40 carbon atoms.

Examples of the olefinically unsaturated monomer represented by the chemical formula 1 are vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane and vinyldimethylethoxysilane. , Allyltrimethoxysilane, allylmethyldimethoxysilane and the like, but vinyltrimethoxysilane is preferable.

Examples of the olefinically unsaturated monomer represented by the chemical formula 2 are N-methoxymethyl acrylamide and N-
Methoxyethyl acrylamide, N-ethoxymethyl acrylamide, N- (n-propoxymethyl) acrylamide, N- (iso-propoxymethyl) acrylamide, N- (n-butoxymethyl) acrylamide and the like can be mentioned, but N- (n- Butoxymethyl) acrylamide is preferred.

Further, as the other olefinically unsaturated monomers, glycidyl acrylate and the like represented by the following general formula can be cited.

[0025]

[Chemical 3]

Here, R ⁵ is a hydrogen atom or a methyl group .

In the present invention, when the above-mentioned crosslinkable olefinically unsaturated monomer is used, the crosslinkable group is introduced into the main chain of EVOH, but the present invention is not limited thereto. By a graft reaction or a post reaction
It can also be introduced into the side chain of VOH.

When the content of the crosslinkable group such as the above-mentioned olefinic unsaturated monomer is too small, the strength of the film becomes insufficient, and when it is too large, the oxygen barrier property which is a characteristic of EVOH is deteriorated. It is not preferable to do so. The content is selected according to each purpose and the kind of the monomer, but 0.0005 to 5 mol%, particularly 0.001
˜3 mol%, more preferably 0.01 to 3 mol%, most preferably 0.05 to 3 mol%.

The composition of the EVOH component in the modified EVOH has an ethylene content of 10 to 70 mol% and a saponification degree of 80 mol%.
(The degree of saponification referred to in the present invention indicates the degree of saponification of vinyl ester units). The preferred range of ethylene content is 12 mol% or more, more preferably 15 mol%
As described above, further 20 mol% or more. The upper limit is preferably 65 mol% or less, more preferably 60 mol% or less. The preferable degree of saponification is 90 mol% or more, and further 95 mol% or more. EVOH with dispersoids
The ethylene content and saponification degree of will be described later,
Those close to that are desirable in terms of the particle dispersion stabilizing effect.
More preferably, almost the same ethylene content and degree of saponification are desired.

The degree of polymerization of the modified EVOH is not particularly limited, but is preferably 100 or more from the viewpoint of the effect of stabilizing dispersion. The upper limit of the degree of polymerization is not particularly limited, but if it is too large, the solution viscosity is high and the dispersion performance is deteriorated.
Those of 00 or less are used. Here, the modified EVOH has a degree of polymerization of water / phenol mixed solvent (weight ratio: 15/8) containing 1 mol / liter of ammonium thiocyanate.
In 5), it is determined from the intrinsic viscosity measured at 30 ° C.

With respect to the structure of the modified EVOH, a so-called random or terminal ionic group is introduced and a crosslinkable group is introduced in the main chain or side chain is preferably used. When long-term storage stability of the aqueous dispersion is more required, modified EVOH with randomly introduced ionic groups
Is preferred. There are no particular restrictions on these manufacturing methods.

For example, a monomer having an ionic group and a monomer having a crosslinkable group are radically copolymerized with ethylene and a vinyl ester, and then the vinyl ester unit in the obtained copolymer is saponified to vinyl alcohol. A method of converting into a unit, a method of radically copolymerizing a monomer having a crosslinkable group with ethylene and vinyl ester, a method of introducing an ionic group-containing component into a copolymer obtained by saponification, or introducing ethylene-vinyl. Examples thereof include a method in which an ionic group-containing component and a crosslinkable group-containing component are subjected to an addition reaction with an ester copolymer, and then the vinyl ester unit in the copolymer is saponified to convert it into a vinyl alcohol unit.

Examples of the addition reaction include Michael addition reaction of an ionic group-containing vinyl monomer to the hydroxyl group, acetalization or ketalization with an ionic group-containing aldehyde or ketone , addition of an ionic group-containing epoxy compound , and sulfuric acid. Esterification etc. are mentioned. In addition , introduction of an ionic group-containing monomer having a low radical homopolymerizability by a radical addition reaction may be mentioned.

Further, a compound having an active group such as an alcohol, an aldehyde or a thiol having a sulfonic acid group or a salt thereof , an ammonium group or the like is made to coexist as a chain transfer agent, and a monomer having an ethylene, a vinyl ester and a crosslinkable group is present. And then saponifying the vinyl ester unit, and a copolymer of ethylene, vinyl ester and a monomer having a crosslinkable group containing a sulfonic acid group or its salt , an ammonium group, etc. It is produced by a method of introducing a compound by a chemical reaction. Among these methods, a method for economically and efficiently introducing an ionic group at the terminal to obtain a modified EVOH exhibiting excellent stability as a dispersion stabilizer is a sulfonic acid group or a salt thereof , or an ammonium group. Preferred is a method in which ethylene, a vinyl ester and a monomer having a crosslinkable group are copolymerized in the presence of a thiol having, and then saponified.

The radical copolymerization is carried out by a known method, that is, a batch method, a semi-batch method, or a continuous method in the presence of a polymerization initiator by solution polymerization, suspension polymerization or emulsion polymerization. It is industrially preferable to carry out the solution polymerization in the presence. In the case of solution polymerization, the solvent concentration is 0 to 50%, preferably 3 to 30%, and the polymerization rate is usually 20 to 80%, preferably 30 to 60%.
The polymerization temperature is usually 20 to 100 ° C., preferably 40 to 8
It is 0 ° C. As the polymerization initiator, 2,2'-azobisisobutyronitrile and 2,2'-azobis- (2,4-
Dimethylvaleronitrile), 2,2'-azobis- (4
-Methoxy-2,4-dimethylvaleronitrile) and other nitriles, di-normal propyl peroxycarbonate, bis-4-tert-butylhexyl peroxydicarbonate, bis-2-ethylhexyl peroxydicarbonate and other carbonates, Known radical polymerization initiators such as benzoyl peroxide, lauroyl peroxide, and peroxides such as acetylcyclohexane sulfonyl peroxide can be used. As the alcohol, lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol and butyl alcohol are used, but from the economical viewpoint, methyl alcohol is preferable.

The copolymer obtained by the polymerization is then subjected to a saponification reaction. For the saponification reaction, it is advantageous to carry out the reaction by a known method using an alkaline catalyst, that is, usually by alcoholysis using the copolymer as an alcohol solution. In particular, Japanese Patent Nos. 575889 and 61155
The most preferable method is to use the tower reactor disclosed in No. 7 and remove methyl acetate produced as a by-product during the saponification reaction while blowing alcohol vapor into the bottom of the tower to remove it from the top of the tower. As the alkaline catalyst, hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide, and alcoholates such as sodium methylate and potassium methylate are used, and sodium hydroxide is particularly preferable from the economical point of view. The saponification reaction temperature is appropriately selected from the range of 60 to 175 ° C. In particular, when the tower reactor is used, it is preferably 100 ° C. or higher from the viewpoint of shortening the reaction time, etc., though it depends on the composition of the copolymer.

A known method is applied for isolating the modified EVOH after the saponification reaction, particularly Japanese Patent 72
The method of depositing in strands as disclosed in No. 5520 is suitable. The modified EVOH isolated by precipitation is washed with water by a known method, and if necessary, a known heat stabilization treatment such as acid treatment is performed, and after drying, a crosslinking catalyst is added if necessary to prepare an aqueous dispersion. Used in manufacturing.

The vinyl ester can be copolymerized with ethylene and olefinically unsaturated monomers such as vinyl formate, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl trifluoroacetate and vinyl pivalate, and the copolymers thereof. One or more monomers that can be converted into vinyl alcohol by saponification of vinyl acetate can be used, but vinyl acetate is particularly preferable from the economical viewpoint.

As the ionic group-containing monomer, a radical homopolymerizable or radical copolymerizable monomer having an ionic group or a functional group convertible to an ionic group can be used. An example is shown below.

Anionic group-containing monomer Sulfonic acid Anionic group-containing monomer includes 2-
(Meth) acrylamido-2-methylpropane sulfonate sodium (meth) acrylamide sulfonate monomer, potassium styrene sulfonate such as styrene sulfonate monomer, sodium allyl sulfonate allyl sulfonate monomer, Further, vinyl sulfonates such as sodium vinyl sulfonate, ammonium salt monomers thereof, and acid monomers thereof may be mentioned. Also, these sulfonic acid esters can be used by converting the ester to a salt or acid after polymerization .

Cationic group-containing monomer: An amino group-containing (meth) acrylamide monomer such as aminopropyl acrylamide or methacrylamide, or an amino group-containing (meth) acrylate such as aminoethyl acrylate or methacrylate or a salt thereof has good polymerizability. preferable. Particularly, the quaternary salt thereof is preferable because it causes less coloring of the polymer. For example, trimethylacrylamidopropylammonium chloride, triethylmethacryloylethylammonium bromide and the like.

These monomers can be used alone or in combination. Copolymerization with other monomers is also possible within a range that does not impair the dispersion stabilizing effect.

Various thiols containing an ionic group such as a sulfonic acid group or a salt thereof , an ammonium group and the like can be used.

Examples of the thiol having a sulfonic acid group or a salt thereof include those represented by the following general formula.

[0045]

[Chemical 4]

[0046]

[Chemical 5]

[0047]

[Chemical 6]

[0048] In this case, k1, k2, and k3 is from 1 to 4
An integer , R ^{6 to} R ^{13 each} represent a hydrogen atom or a methyl group, and M represents a hydrogen atom or an alkali metal.

As the thiol having an ammonium group,
Examples include those represented by the following general formula.

[0050]

[Chemical 7]

[0051]

[Chemical 8]

[0052]

[Chemical 9]

[0053]

[Chemical 10]

Here, j1 is an integer of 0 to 3 , and j2 is 1 to
10 integer, R ^{14, R 15, and,} R 18 ^{to R 20}
Is a hydrogen atom or a methyl group, and R ¹⁶ and R ^{17 each} have 1 carbon atom
-10, preferably an alkyl group having 1 to 5 carbon atoms (which may contain a substituent), A is an amine or ammonium nitrogen atom and the nitrogen atom of the amide group in formula 7 or oxygen in formula 9 Each of the groups connecting the atom is shown.

EVOH, which is a dispersoid polymer, comprises ethylene and vinyl acetate, vinyl formate, vinyl propionate,
A vinyl ester such as vinyl benzoate, vinyl trifluoroacetate, vinyl pivalate, etc., particularly an ethylene-vinyl alcohol copolymer obtained by copolymerizing with vinyl acetate and saponification, having an ethylene content of 15 to 65 mol%, The degree of saponification must be 90 mol% or more. If the ethylene content is less than 15 mol%, the stability of the aqueous dispersion will be poor, and if it exceeds 65 mol%, the gas barrier property will be poor, such being unsuitable. From the viewpoint of stability of the aqueous dispersion and gas barrier properties, the ethylene content is preferably 20 to 55 mol%. If the saponification degree is less than 90 mol%, the gas barrier property becomes insufficient, so that it is necessary to use one having 90 mol% or more. The higher the degree of saponification, the higher the gas barrier.
It has high properties, and is preferably 95 mol% or more, more preferably 97 mol% or more.

The degree of polymerization of EVOH of the dispersoid is selected according to the application, but an extremely low degree of EVOH is usually not less than 400 and preferably not less than 700, because the strength of the formed film is not preferable. The higher the degree of polymerization is, the more advantageous it is to use by coating as an aqueous dispersion, and usually, it can be used up to about 5000. Here, the degree of polymerization of the dispersoid is water /
30 ° C in phenolic mixed solvent (weight ratio 15/85)
It is determined from the intrinsic viscosity measured in. If necessary, 5 mol% or less of a copolymerizable monomer other than ethylene and vinyl ester may be copolymerized.

The amount of the modified EVOH used as the dispersion stabilizer is appropriately selected in consideration of the kind and content of the ionic group, but is 2 to 200 parts by weight, preferably 3 parts by weight with respect to 100 parts by weight of the EVOH of the dispersoid. To 100 parts by weight, more preferably 5 parts
˜50 parts by weight is desirable. If the amount is too small, the dispersion stability will be poor, and if it is too large, the gas barrier properties of the formed film will be insufficient, which is unsuitable.

There is no limitation on the method of dispersing the EVOH which is a dispersoid using the modified EVOH as a dispersion stabilizer, and known methods can be used. For example, a solution of EVOH which is a dispersoid is added to EVOH in the presence of modified EVOH which is a dispersion stabilizer.
The EVOH particles can be precipitated as fine particles of 3 μm or less, preferably 2 μm or less, optimally 1 μm or less by contact with water, which is a non-solvent, under agitation, and then the solvent is removed to obtain an aqueous dispersion. . Here, the diameter of the fine particles is the number average particle diameter.

The solid content concentration of the aqueous dispersion is appropriately determined depending on the production conditions, intended use, etc., but the feature of the present invention is that a high concentration and stable dispersion can be obtained. The solid content concentration is 10% by weight or more, more preferably 15%.
It is at least 20% by weight, most preferably at least 20% by weight. The upper limit of the solid content concentration is not particularly limited, but if the concentration is too high, the stability of the aqueous dispersion may be slightly poor. Therefore, it is preferably 60% by weight or less, more preferably 50% by weight. % Or less, optimally 40% by weight or less.

Examples of the solvent include methyl alcohol,
Ethyl alcohol, propyl alcohol, butyl alcohol and other monohydric alcohols, ethylene glycol, propylene glycol and other dihydric alcohols, glycerin and other 3
Dihydric alcohol, phenol, phenols such as cresol, amines such as ethylenediamine and trimethylenediamine, dimethylsulfoxide, dimethylacetamide,
N-methylpyrrolidone and the like, or hydrates thereof and the like can be used alone or in admixture of two or more. Particularly preferred solvents are alcohol-water mixed solvents such as water-methyl alcohol, water-normal propyl alcohol and water-isopropyl alcohol.

The modified EVOH can coexist in a solution of EVOH which is a dispersoid, in water of a non-solvent, or both, but it is preferable to coexist in a solution of EVOH.

The organic solvent in the solvent can be removed by an appropriate method such as an evaporation method, an extraction method or a dialysis method. It is desirable that the degree of removal is high, but it is possible to leave a small proportion of the organic solvent remaining in consideration of economical efficiency.

As another method for obtaining an aqueous dispersion, a modified solvent E which is soluble at high temperature but insoluble at low temperature is used.
It is also possible to employ a method in which VOH is heated and dissolved, and then the solution is cooled to precipitate and disperse the fine particles. Then, the solvent is replaced with water to form an aqueous dispersion. As the solvent which dissolves at a high temperature but becomes insoluble at a low temperature, alcohols alone or a mixed solvent with water among the above-mentioned solvents can be used.

As a further method, a method in which a solution of modified EVOH is brought into contact with a non-solvent or cooled to precipitate and disperse the particles, and the particles are dispersed in an aqueous medium is also possible. .

In the present invention, a preferable method for producing an aqueous dispersion is EVOH as a dispersoid and modified EVOH as a dispersion stabilizer.
Are dissolved in these common solvents, for example, a mixed solvent of water-alcohol at a temperature of 50 to 75 ° C. under stirring to form a solution, which is then cooled (temperature of −10 to 30 ° C.) to precipitate EVOH particles. Disperse (emulsify), then alcohol under reduced pressure (temperature 10 to 30 ° C, pressure 10 to 150 mmHg).
By removing the desired amount of water
Examples thereof include a method of obtaining an aqueous dispersion having a desired solid content concentration.

The aqueous dispersion of the present invention contains alkali metal compounds such as sodium hydroxide, sodium chloride, sodium acetate, sodium sulfate and sodium nitrate, calcium hydroxide, calcium chloride, calcium acetate and calcium sulfate for the purpose of decreasing the viscosity. , Alkaline earth metal compounds such as calcium nitrate, and other electrolytes from 0.01 to
You may mix | blend 0.5 weight% (with respect to polymer). The composition is
It may be before or after atomizing the EVOH of the dispersoid.

A crosslinking catalyst is added to the aqueous dispersion, if necessary. The type of the cross-linking catalyst varies depending on the type and content of the olefinically unsaturated monomer, but generally, inorganic acids such as sulfuric acid and phosphoric acid, organic acids such as acetic acid, oxalic acid and succinic acid,
An acid anhydride such as phthalic anhydride and a strong acid ammonium salt such as ammonium chloride and ammonium sulfate are used.

The aqueous dispersion obtained by the method of the present invention is useful as a coating material for forming a film having an excellent gas barrier property, but by utilizing its excellent mechanical performance and chemical performance, it can be used for other purposes. For example, you can use atomization drying to make fine powder,
It can also be used in a wide range of applications such as binders and vehicles for paints and adhesives.

It is possible to add a usual surfactant or protective colloid to the aqueous dispersion of the present invention, if necessary, within a range not hindering the object of the present invention. It is also possible to add an aqueous dispersion of another resin, a stabilizer against light or heat, a pigment, a lubricant, a fungicide or a film-forming auxiliary. Further, the dispersion stabilizer of the present invention is most suitable as the above-mentioned EVOH dispersion stabilizer, but other organic materials (resins)
It can also be used as a dispersion stabilizer for inorganic materials.

As described above, according to the present invention, an aqueous dispersion having a high solid content concentration which is excellent in stability during storage or use can be obtained, and since it is aqueous, there is no problem such as environmental pollution. It has an advantage and can be applied to various substrate surfaces as a useful coating agent capable of forming a thin film having excellent gas barrier property, aroma retaining property and oil / chemical resistance by coating and drying. Here, as the base material, particularly thermoplastic resin (polyolefin (polyethylene, polypropylene, etc.), polyester, polyamide, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polystyrene, polyvinyl alcohol, vinyl acetate resin (ethylene-vinyl acetate copolymer) Various types of molded articles (films, sheets, cups, bottles, etc.), etc., and fiber aggregates (paper, non-woven fabric, woven fabric, fibrous casing, etc.), inorganic materials (cement, etc.) ), Metal, polyvinyl chloride wallpaper, photographic paper, etc.

The method of applying the aqueous dispersion of the present invention onto the surface of a substrate includes discharging from a casting head,
Any means such as roll coating, doctor roll coating, doctor knife coating, curtain flow coating, spraying, dipping and brush coating is exemplified. Examples of the method for drying and heat treating the substrate thus coated include a dry heat treatment method such as an infrared irradiation method and a hot air drying method. These infrared irradiation and hot-air drying may be used alone or in combination. Dry again
The temperature of the heat treatment is preferably 30 to 180 ° C,
The lower limit is preferably 50 ° C or higher, and optimally 80
℃ or above. The drying / heat treatment time is preferably 5 seconds to 10 minutes, more preferably 1 to 5 minutes. During the drying / heat treatment, conditions such as increasing or decreasing the temperature, for example, treating at a low temperature at the beginning and gradually raising the temperature are free. By performing such drying and heat treatment, a film having an excellent gas barrier property is formed on the surface of the base material.

The thickness of the coating after coating, drying and heat treatment of the aqueous dispersion of the present invention is preferably 0.5 to 15 μm, more preferably 1 to 10 μm, most preferably 2 to 6 μm. is there.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Parts or% in the examples are expressed by weight unless otherwise specified. The solvent composition is also shown by weight ratio.

[0074]

EXAMPLE 1 Sodium 2-acrylamido-2-methylpropanesulfonate unit was 2.2 mol% based on the EVOH component, and N-
(N-butoxymethyl) acrylamide unit is EVOH
Water containing 10% of modified EVOH having an ethylene content of 38 mol%, a saponification degree of 99.6 mol%, and a polymerization degree of 950, which were each randomly copolymerized with 1.3% of the components.
50 parts of a mixed solvent solution of methyl alcohol = 45/55 was added to and mixed with 30 parts of ordinary EVOH having an ethylene content of 38 mol%, a saponification degree of 99.5 mol% and a polymerization degree of 1000, 100 parts of methyl alcohol and 100 parts of water. ℃
It melted by heating.

When this solution was cooled to 5 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle size was 0.5 μm. Ammonium chloride 0.0
7 parts were added and then evaporated under reduced pressure at 20 ° C. with stirring to distill off the methyl alcohol. Agglomeration of particles was hardly seen even in the process of distilling off methyl alcohol, and stable, and an aqueous emulsion dispersion having an average particle diameter of 0.5 μm and a solid content concentration of 25% was obtained. Further, the storage stability was good, and almost no aggregation was observed in the storage test at 40 ° C. for 10 days.

This aqueous dispersion was applied onto the primer-treated surface of a biaxially stretched polypropylene film, dried at 110 ° C. for 2 minutes, and then heat-treated at 145 ° C. for 5 minutes to obtain a uniform thickness of 5 μm.
A coating film with good transparency was obtained. The oxygen transmission rate of this film is 3.8 cc / m ² · day · atm (20 ° C, 0%
RH) showed good performance as a food packaging material (hereinafter, the unit of oxygen permeation amount is the same unit). Separately, using the above aqueous dispersion, drying and heat treatment were similarly performed to obtain a monolayer film having a thickness of 8 μ, and the tensile strength at break was measured at 20 ° C. and 65% RH. ² in
It had sufficient strength to withstand use.

Comparative Examples 1 to 4 In Example 1, instead of the modified EVOH, ethylene content was 38 mol%, saponification degree was 99.2 mol%, N- (n-butoxymethyl) acrylamide content was 1.0 mol%, and polymerization degree was When dispersed using 900 EVOH (Comparative Example 1), ethylene oxide adduct of nonyl phenyl ether of a nonionic surfactant known as a dispersant in this EVOH (Comparative Example 2), and anionic surfactant dodecyl When sodium benzenesulfonate (Comparative Example 3) or partially saponified polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 600 was used as a polymer protective colloid (Comparative Example 4), otherwise, under the same conditions as in Example 1. Attempts were made to disperse, but in both cases, particles aggregated / blocked at the stage of cooling the solution that had been heated and dissolved under stirring. Oops.

Example 2 A thiolized product of sodium 2-acrylamido-2-methylpropane sulfonate was introduced at the end of the molecule, and vinyltrimethoxysilane was added to the EVOH component at 0.
Modified EV with 6 mol% random copolymerization, ethylene content 35 mol%, degree of saponification 99.8 mol%, degree of polymerization 750
Water containing 10% OH / methyl alcohol = 50/5
50 parts of a mixed solvent solution of 0, ethylene content 35 mol%,
Normal EVO with a saponification degree of 99.7 mol% and a degree of polymerization of 800
20 parts of H, 100 parts of methyl alcohol and 100 parts of water were added and mixed, and heated and dissolved at 65 ° C.

When this solution was cooled to 5 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle size was 0.8 μm. Then, the mixture was evaporated under reduced pressure at 20 ° C. with stirring to distill off methyl alcohol. Agglomeration of particles was hardly observed even in the process of distilling off methyl alcohol, and stable, and an aqueous emulsion dispersion having an average particle diameter of 0.8 μm and a solid content concentration of 24% was obtained. The storage stability was also good, and almost no aggregation was observed in the storage test at 30 ° C. for 10 days.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (film thickness 5 μm) was 3.0, and the monolayer film obtained in the same manner as in Example 1 had a temperature of 20 ° C. and 65%.
The tensile strength at break under the condition of% RH is 3.8 kg / mm ^2.
Met.

Example 3 1.5 mol% of potassium 2-acrylamido-2-methylpropanesulfonate was randomly copolymerized with respect to the EVOH component, and 0.5 mol% of vinyltrimethoxysilane component was randomly copolymerized with respect to the EVOH component. , Ethylene content 30 mol%,
Modified EVOH with a saponification degree of 99.7 mol% and a degree of polymerization of 810
50 parts of a mixed solvent solution of water / methyl alcohol = 50/50 containing 10% of ethylene, an ordinary EVOH2 having an ethylene content of 31 mol%, a saponification degree of 99.7 mol%, and a polymerization degree of 880.
0 parts, 100 parts of methyl alcohol and 100 parts of water were added and mixed, and the mixture was heated and dissolved at 65 ° C.

When this solution was cooled to 10 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle diameter was 0.7 μm. Then, it was evaporated under reduced pressure at 25 ° C. with stirring to distill off methyl alcohol. Even in the process of distilling methyl alcohol, there is almost no aggregation of particles and it is stable.
An aqueous emulsion dispersion having an average particle diameter of 0.7 μm and a solid content concentration of 21% was obtained. It also has good storage stability, 10 at 40 ° C.
Almost no agglomeration was observed in the day standing test.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (film thickness 5 μ) was 2.9, and the monolayer film obtained in the same manner as in Example 1 had a temperature of 20 ° C. and a value of 65.
The tensile strength at break under the conditions of% RH is 4.0 kg / mm ^2.
Met. In addition, a polyethylene terephthalate resin blow-molded with a volume of 1 liter and a thickness of 200 μ is
After immersing in the above aqueous dispersion and drying at 90 ° C. for 3 minutes, 150
After heat treatment for 2 minutes at 0 ° C., a container having a modified EVOH film having a thickness of 8 μ and good appearance and transparency was obtained.

Example 4 Sodium allyl sulfonate unit was 0.8 mol% based on the EVOH component, and glycidyl methacrylate unit was EV.
0.5 mol% was randomly copolymerized with respect to the OH component,
50 parts of a mixed solvent solution of water / isopropyl alcohol = 50/50 containing 10% of modified EVOH having an ethylene content of 25 mol%, a saponification degree of 99.5 mol%, and a polymerization degree of 1100, and an ethylene content of 25 mol%, a saponification degree of 99 0.7 parts by mole of EVOH having a polymerization degree of 1150, 100 parts of isopropyl alcohol and 100 parts of water were added and mixed, and the mixture was heated and dissolved at 65 ° C.

When this solution was cooled to 10 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle diameter was 0.6 μm. Then, the mixture was evaporated under reduced pressure at 25 ° C. with stirring to remove isopropyl alcohol. Even in the process of distilling off isopropyl alcohol, particles were hardly aggregated and stable, with an average particle size of 0.6 μm and a solid content concentration of 27 μm.
% Aqueous emulsion dispersion was obtained. In addition, leaving stability is also good,
In the 10-day storage test at 40 ° C., almost no aggregation was observed.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (film thickness 5 μm) was 3.0, and the monolayer film obtained in the same manner as in Example 1 had a temperature of 20 ° C. and 65%.
The tensile strength at break under the condition of% RH is 4.1 kg / mm ^2.
Met.

EXAMPLE 5 2.1 mol% of vinyltrimethoxysilane was randomly copolymerized with respect to the EVOH component. The hydroxyl groups of EVOH were sulfate-esterified to neutralize 1/2 equivalent of the sulfate anion groups. The synthesized sulfate anion group is E
4.3 mol% of ethylene content added to VOH component 42 mol%, saponification degree 99.7 mol%, polymerization degree 9
50 parts of a mixed solvent solution of water / methyl alcohol = 30/70 containing 15% modified EVOH of 00, ethylene content 44 mol%, saponification degree 99.7 mol%, polymerization degree 850
80 parts of ordinary EVOH, 560 parts of methyl alcohol and 240 parts of water were added and mixed, and dissolved by heating at 65 ° C.

When this solution was cooled to 3 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle size was 0.4 μm. Then, the mixture was evaporated under reduced pressure at 20 ° C. with stirring to distill off methyl alcohol. Agglomeration of particles was hardly observed even in the process of distilling methyl alcohol, and stable, and an aqueous emulsion dispersion having an average particle diameter of 0.4 μm and a solid content concentration of 28% was obtained. Further, the storage stability was good, and almost no aggregation was observed in the storage test at 40 ° C. for 10 days.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (film thickness 5 μ) was 4.2, and the monolayer film obtained in the same manner as in Example 1 had a temperature of 20 ° C. and 65 ° C.
% Tensile strength at 4.8 kg / mm ²
Met.

Example 6 2-methacrylamido-2 was obtained by Michael addition reaction of EVOH in which 0.3 mol% of allyltrimethoxysilane component was randomly copolymerized with EVOH component to hydroxyl groups.
Water / methyl alcohol containing modified EVOH having an ethylene content of 32 mol%, a saponification degree of 99.3 mol%, and a polymerization degree of 1230, which is obtained by adding sodium methyl propanesulfonate to the EVOH component in an amount of 2.5 mol%. Fifty
50 parts of a mixed solvent solution of 50/50 with 15 parts of ordinary EVOH having an ethylene content of 33 mol%, a saponification degree of 99.8 mol% and a polymerization degree of 1200, 100 parts of methyl alcohol and 1 part of water.
The mixture was added to 00 parts and mixed, and dissolved by heating at 65 ° C.

When this solution was cooled to 20 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle size was 0.8 μm. Then, the mixture was evaporated under reduced pressure at 20 ° C. with stirring to distill off methyl alcohol. Even in the process of distilling methyl alcohol, there is almost no aggregation of particles and it is stable.
An aqueous emulsion dispersion having an average particle diameter of 0.8 μm and a solid content concentration of 21% was obtained. It also has good storage stability, 10 at 40 ° C.
Almost no agglomeration was observed in the day standing test.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (film thickness 5 μ) was 4.5, and the monolayer film obtained in the same manner as in Example 1 had a oxygen content of 65 ° C. and 65 ° C.
The tensile strength at break under the condition of% RH is 3.8 kg / mm ^2.
Met.

Example 7 Sodium allylsulfonate unit was 2.8 mol% based on the EVOH component, and vinyltrimethoxysilane unit was EV.
1.0 mol% was randomly copolymerized with respect to the OH component,
A solution was prepared by dissolving 2000 parts of water in 250 parts of modified EVOH having an ethylene content of 27 mol%, a saponification degree of 99.1 mol% and a polymerization degree of 370. A high-speed stirrer is immersed in this solution, and the ethylene content is 2 while stirring at 5000 rpm.
7 parts by mol of EVOH having a degree of saponification of 99.6 and a degree of polymerization of 1050 dissolved in a mixed solvent of ethyl alcohol / water = 50/50 was added dropwise 5000 parts of a solution having a concentration of 10%. A dispersion was obtained. The average particle size was 0.9 μm.

Then, the mixture was evaporated under reduced pressure at 20 ° C. with stirring to remove ethyl alcohol. Agglomeration of particles was hardly observed even in the process of distilling off ethyl alcohol, and an aqueous emulsion dispersion having an average particle diameter of 0.9 μm and a solid content concentration of 20% was obtained. Further, the storage stability was good, and almost no aggregation was observed in the storage test at 40 ° C. for 10 days.

This aqueous dispersion was applied in the same manner as in Example 1,
The amount of oxygen permeation of the dried film (thickness 5 μm) was 3.5, and the monolayer film obtained in the same manner as in Example 1 was 20 ° C. and 65%.
The tensile strength at break under the condition of% RH is 3.6 kg / mm ^2.
Met.

Example 8 Instead of the sodium 2-acrylamido-2-methylpropanesulfonate of Example 1, modified EVOH (N- (n-butoxymethyl) acrylamide unit in which trimethylacrylamidopropylammonium chloride was copolymerized and modified in the same amount. Also, except that the same amount of copolymerization as in Example 1) is used, the dispersion is carried out under the same conditions as in Example 1 and the methyl alcohol is distilled off. The average particle diameter is 0.7 μm, and the solid content concentration is 22%. An aqueous emulsion dispersion was obtained. Further, the storage stability was good, and almost no aggregation was observed in the storage test at 40 ° C. for 10 days.

This aqueous dispersion was applied in the same manner as in Example 1,
The oxygen permeation amount of the dried film (film thickness 5 μ) was 3.9, and the monolayer film obtained in the same manner as in Example 1 had a temperature of 20 ° C. and 65%.
The tensile strength at break under% RH condition is 4.3 kg / mm ^2.
Met.

[0098]

By using the modified EVOH of the present invention as a dispersion stabilizer, an aqueous dispersion having a high solid content concentration, particularly an aqueous emulsion dispersion, which is excellent in stability during storage or use, can be obtained and is Therefore, there is no problem of environmental pollution. Further, it has high industrial value which can be used as a coating agent which shows excellent gas barrier property, aroma retaining property and oil / chemical resistance by coating and drying and can form a thin film having strong strength.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C09D 129/04 C09D 129/04 (56) References JP 60-262869 (JP, A) JP 57-64519 (JP , A) JP-A-4-225032 (JP, A) JP-A-3-269110 (JP, A) JP-A-4-122756 (JP, A) JP-A-5-186649 (JP, A) JP-A 51-19040 (JP, A) JP-A-2-227174 (JP, A) JP-B-47-48489 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 23/26 B01F 17/52 C08L 29/04 C08L 51/06 C09D 123/26 C09D 129/04

Claims (5)

(57) [Claims] 1. Sulfonic acid and its salts, sulfates
And its salts, phosphoric acid and its salts, amines and its
Salt, quaternary ammonium salt, phosphonium salt and sulfur
Having at least one ionic group selected from the group consisting of ruphonium salts and having a crosslinking group of 0.0005 to 5 mol%, an ethylene content of 10 to 70 mol% and a saponification degree of 80 mol% The above modified ethylene-vinyl alcohol copolymer . 2. The ionic group is randomly or terminally
The modified ethylene-bi according to claim 1, which is introduced into
Nyl alcohol-based copolymer. 3. The crosslinkable group is introduced into the main chain or side chain.
The modified ethylene-bi according to claim 1 or 2,
Nyl alcohol-based copolymer. 4. A dispersion stabilizer comprising the modified ethylene-vinyl alcohol copolymer according to any one of claims 1 to 3 . 5. An aqueous dispersion containing an ethylene-vinyl alcohol copolymer having an ethylene content of 15 to 65 mol% as a dispersoid, which uses the dispersion stabilizer according to claim 4 .