JPH0616747A - Dispersion stabilizing agent and aqueous dispersion - Google Patents

Abstract

PURPOSE:To provide a dispersion stabilizer composed of a specific copolymer and giving an aqueous dispersion of an ethylene-vinyl alcohol copolymer having excellent stability in storage and use, exhibiting high solid concentration and giving a coating film having excellent barrierness. CONSTITUTION:The stabilizing agent is composed of a copolymer produced by bonding (A) a saponified ethylene-vinyl ester copolymer having an ethylene content of 10-70mol% and a degree of saponification of >=80mol% to (B) a polyether component (preferably composed mainly of oxyethylene unit) in the form of a block or graft copolymer. The copolymer is produced, e.g. in the case of a graft copolymer, by copolymerizing a polyether having double bond on a terminal with ethylene and a vinyl ester and saponifying the obtained copolymer. The content of the component B is preferably 5-50 pts.wt. based on 100 pts.wt. of the component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous dispersion of a dispersion stabilizer and an ethylene-vinyl alcohol copolymer.

[0002]

2. Description of the Related Art Ethylene-vinyl ester copolymer, particularly ethylene-vinyl alcohol copolymer obtained by saponifying ethylene-vinyl acetate copolymer (abbreviated as EVOH).
Has excellent gas barrier properties against oxygen, etc. and oil / chemical resistance, and is therefore attracting attention as a material for packaging materials and as a protective coating material for plastic moldings, 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, etc. made of soft vinyl chloride, a coating material 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 is noted 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 collecting the organic solvent is required, which is economically disadvantageous. In contrast, EVOH
The method of applying the aqueous dispersion of is considered to be advantageous because the solvent is aqueous and is considered to be advantageous from the viewpoint of the above-mentioned working environment and economy.

As an aqueous dispersion of EVOH, a conventional E
What was obtained by emulsifying and dispersing VOH in the presence of an ordinary surfactant or an ordinary polymer protective colloid, for example, polyethylene oxide, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, etc. is disclosed in JP-A-54-101844 and JP-A-56- 61430 and the like. However, according to the study by the present inventors, the aqueous dispersion of EVOH obtained by these known methods has insufficient dispersion stability and is difficult to be practically used for coating.

Further, in JP-A-54-101844, a carboxylic acid group-containing monomer such as acrylic acid or maleic anhydride is terpolymerized with ethylene and vinyl acetate and saponified to obtain a so-called random copolymerization. It has been shown that EVOH itself containing a carboxyl anion group is dispersed using a usual surfactant as a dispersion stabilizer.

However, when the so-called random carboxyl anion-modified EVOH itself is dispersed, since the ionic groups are randomly contained in the entire EVOH, a large amount is copolymerized in order to achieve sufficient dispersion stability. It is necessary to do so, and if so, the crystallinity of EVOH is lowered, the structure is greatly disturbed, and the barrier property of the formed film is lowered.

[0009]

DISCLOSURE OF THE INVENTION The present invention was devised in order to overcome the above-mentioned drawbacks of the prior art, and a dispersion stabilizer excellent in dispersion stability of dispersoids, particularly EVOH, is provided. EVO with excellent barrier property of formed film used
It is an object to provide an H-based aqueous dispersion, particularly an EVOH-based aqueous emulsion dispersion.

[0010]

The above object is achieved by providing a dispersion stabilizer consisting of an EVOH block or graft copolymer in which a polyether component is bonded to the EVOH component in a block or graft form. It

The first feature of the present invention is that the EVOH-based aqueous dispersion is remarkably improved in stability during storage or use and is excellent in dispersion stability. The second feature of the present invention is that the dispersion stability is excellent, and there is almost no significant increase in the particle size due to the aggregation of the particles during storage or use, so that a film-forming property is good and a thinner uniform film can be applied. The dried film has excellent barrier properties.

The dispersion stabilizer of the present invention has an ethylene content of 10
Ethylene-vinyl alcohol block or graft in which the saponified ethylene-vinyl ester copolymer component (A) having a saponification degree of 70 mol% or more and a saponification degree of 80 mol% or more is bonded to the polyether component (B) in a block or graft form. The copolymer includes a copolymer (hereinafter abbreviated as polyether-modified EVOH and is divided by a block or graft after it), and there is no limitation on its production method and the like.

The composition of the EVOH component (A) in the polyether-modified EVOH is such that the ethylene content is 10 to 70 mol% and the saponification degree is 80 mol% (the saponification degree in the present invention indicates the saponification degree of vinyl ester units) or more. Need to be The preferable range of the ethylene content is 12 mol% or more, more preferably 15 mol% or more, and 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.
The ethylene content and the degree of saponification of EVOH of the dispersoid will be described later, but those close to that are preferable 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 is not particularly limited, but is preferably 20 or more from the viewpoint of the effect of stabilizing dispersion. The degree of polymerization is measured by a viscosity method as in ordinary EVOH.

The polyether component (B) used in the present invention, which will be described in detail later, includes those mainly composed of oxyalkylene units such as oxyethylene units, oxypropylene units and oxytetramethylene units. However, those mainly containing oxyethylene units are preferable from the viewpoint of the effect of stabilizing the aqueous emulsion dispersion. The polyether molecule may contain, for example, a polymethylene unit, an amide group, a urethane group, an ester group or a phenyl group.

The content of the polyether component (B) is appropriately selected within a range having a dispersion stabilizing effect, but from the viewpoint of the dispersion stabilizing effect, it is 1 to 100 parts by weight of the EVOH component (A). 100 parts by weight is desirable. More preferably 3
-80 parts by weight, optimally 5-50 parts by weight. If it is less than 1 part by weight, the effect of stabilizing dispersion is small, and if it exceeds 100 parts by weight, the gas barrier property of the formed film is deteriorated, which is not preferable.

The method for producing the polyether-modified EVOH is not limited, but examples thereof are as follows.

(A) Polyether-modified EVOH block (i) Radical copolymerization of ethylene and vinyl ester in the presence of a polyether having a thiol group at the terminal to give a polyether and ethylene-vinyl ester copolymer. It is possible to obtain a block copolymer obtained by converting the vinyl ester unit to a vinyl alcohol unit by saponifying the vinyl ester unit to obtain a block copolymer in which the polyether and EVOH are bonded via a sulfur atom (S).

The polyether having a thiol group at the terminal can be obtained by subjecting a thiocarboxylic acid such as thioacetic acid and a polyether having a double bond at the terminal to an addition reaction in the presence of a peroxide such as benzoyl peroxide. It is obtained by synthesizing a polyether having a thioester group in the following and then decomposing the terminal thioester group with sodium hydroxide or the like to convert it into a thiol group.

(Ii) On the contrary, ethylene and vinyl ester are radically copolymerized in the presence of thiocarboxylic acid such as thioacetic acid, and then saponified to obtain a terminal thiol group-containing EVOH in the presence of a double terminal. By radically polymerizing a polyether having a bond, a block copolymer in which the polyether and EVOH are bonded via a sulfur atom can be obtained.

(B) Polyether-modified EVOH graft product (a) Polyether-modified EVOH grafted with polyether by copolymerizing a polyether having a double bond at the terminal, ethylene and vinyl ester, and then saponifying An EVOH graft is obtained.

(B) The EVOH is polyether-polymerized by radical polymerization of the polyether having a polymerizable double bond by a usual method, that is, a method of irradiating radiation or an ultraviolet ray, a method of coexisting with a peroxide, etc. in EVOH. A polyether-modified EVOH graft body in which is grafted is obtained.

Here, the polyether having a double bond at the terminal is exemplified below. However, in the following general formula, R ¹ is hydrogen or a methyl group, R ² , R ³ , and R ⁵ are hydrogen or an alkyl group having 1 to 10 carbon atoms, R ⁴ is hydrogen,
X is a C1-10, such as a C1-C10 alkyl group, an alkyl ester group (C1-C10 in an alkyl group), an alkylamide group (C1-C10 in an alkyl group), etc.
Of alkylene group, substituted alkylene group (having 1 to 10 carbon atoms in the alkylene group), phenylene group (having 1 to 10 carbon atoms in the phenylene group), substituted phenylene group (having 1 to 10 carbon atoms in the phenylene group), and n is An integer from 1 to 100, and m is 0
Alternatively, each represents an integer of 1 to 20.

[0023]

[Chemical 1]

[0024]

[Chemical 2]

[0025]

[Chemical 3]

[0026]

[Chemical 4]

[0027]

[Chemical 5]

As described above, the polyether-modified EVOH can be produced by various methods, but the production efficiency (block or graft efficiency) of the block- or graft-type polyether-modified EVOH is not 100% theoretically, and each homo-modified EVOH is homogenous. Polymer polyether and EVOH
Is a byproduct. It is preferable that the efficiency is high, but it is usually difficult to strictly separate the homopolymer produced as a by-product, and EVOH is available as a dispersoid,
If the amount of the polyether homopolymer is not too large, it is not always necessary to remove those homopolymers, and those containing the homopolymer can be dispersed as they are.

Therefore, the polyether-modified E of the present invention
VOH is a polyether and EVO produced as a by-product during its production.
A block or graft reaction product which also includes a homopolymer of H is included, and the block amount or graft amount of the polyether component in the present invention is an apparent amount including the homopolymer based on the weight of the EVOH component. It means the weight of the block component or the graft component. However, it is preferable that the content of the polyether homopolymer is small, and the polyether homopolymer may be removed as necessary.

EVOH, which is a dispersoid polymer used in the present invention, is a vinyl ester of ethylene and vinyl acetate, vinyl formate, vinyl propionate, vinyl benzoate, vinyl trifluoracetate, vinyl pivalate, etc., particularly vinyl acetate. It is an ethylene-vinyl alcohol copolymer obtained by copolymerization and saponification with
It must be 65 mol% and the degree of saponification 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 90
It is necessary to use one having a mol% or more. The higher the degree of saponification, the higher the gas barrier property, and it is preferably 95 mol% or more, more preferably 97 mol% or more.

The degree of polymerization of EVOH as the dispersoid is selected according to the application, but an extremely low degree of EVOH is not preferred because the strength of the formed film is low and is not preferred. 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.

Polyether-modified EVO which is a dispersion stabilizer
The amount of H used is appropriately selected in consideration of the type and content of the polyether component, but is 2 to 200 parts by weight, preferably 3 to 100 parts by weight, and more preferably 5 parts by weight with respect to 100 parts by weight of EVOH of the dispersoid. ˜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 EVOH, which is a dispersoid, using the polyether-modified EVOH as a dispersion stabilizer, and known methods can be used. For example, a solution of EVOH, which is a dispersoid, is modified with a polyether-modified E that is a dispersion stabilizer.
In the presence of VOH, EVOH particles are contacted with water, which is a non-solvent of EVOH, with stirring to bring EVOH particles to 3 μm or less, preferably 2 μm.
m or less, optimally 1 μm or less
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 it is a feature of the present invention that a stable dispersion having a high concentration 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. A particularly preferred solvent is a water-alcohol-based mixed solvent such as water-methyl alcohol, water-normal propyl alcohol, water-isopropyl alcohol and the like.

The polyether-modified EVOH as a dispersion stabilizer can be made to 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 a small proportion of the organic solvent may be left in consideration of economical efficiency.

As another method, the EVOH of the dispersoid and the polyether-modified EVOH of the dispersion stabilizer are heated and dissolved in a solvent which dissolves at a high temperature but becomes insoluble at a low temperature, and then the solution is cooled to obtain fine particles. A method of depositing and dispersing can also be adopted. Then, the solvent is replaced with water to form an aqueous dispersion. As the solvent which dissolves at a high temperature and precipitates at a low temperature, alcohols alone or a mixed solvent with water among the above-mentioned solvents can be used.

As still another method, a solution of a dispersoid EVOH in the presence of a polyether-modified EVOH as a dispersion stabilizer is brought into contact with a non-solvent or cooled to precipitate and disperse the particles. A method of dispersing the particles in water in the coexistence of the polyether-modified EVOH is also possible.

In the present invention, the preferred method for producing an aqueous dispersion is to disperse EVOH as a dispersoid and polyether-modified EVOH as a dispersion stabilizer in a common solvent of them, for example, a mixed solvent of water-alcohol, at a temperature of Dissolve at 50-75 ° C to give a solution, then cool (temperature-10-30 ° C) and EV
OH particles are precipitated and dispersed (emulsified), and then under reduced pressure (temperature 10 to 30 ° C., pressure 10 to 150 mmH).
A method of obtaining an aqueous dispersion having a desired solid content concentration by removing alcohol in g) and further removing a desired amount of water can be mentioned.

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.

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 impairing 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 of 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 discharge 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 film 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.

The present invention will be specifically described below with reference to examples, but the invention is not limited to the examples. The parts in the examples are parts by weight unless otherwise specified. The solvent composition is also shown by weight ratio.

[0048]

【Example】

Example 1 A polyoxyethylene allyl ether having a double bond at the terminal and a molecular weight of 1500 (UNIOX PKA-500 manufactured by NOF CORPORATION) was produced by the method of Production Example (a)-(i).
5) and thioacetic acid are subjected to an addition reaction in the presence of benzoyl peroxide, and then the thioester group is decomposed with sodium hydroxide to obtain a polyether having a thiol group at the terminal. Using this as a chain transfer agent, ethylene and vinyl acetate are used. EVOH having an ethylene content of 32 mol%, a saponification degree of 99.6 mol% and a polymerization degree of 750 by copolymerizing and
A polyether-modified EVOH block body was obtained in which 31 parts by weight of the polyether component (B) was block-bonded to the end of 100 parts by weight of the component (A) through a sulfur atom.

50 parts of a mixed solvent solution of water / methyl alcohol = 50/50 containing 10% of this polyether-modified EVOH block was used, usually with an ethylene content of 32 mol%, a saponification degree of 99.5 mol% and a polymerization degree of 1000. EVOH
50 parts, 200 parts of methyl alcohol and 200 parts of water were added and mixed, and dissolved by heating at 70 ° 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 0.4 μm. The dispersion is then stirred for 2
It was evaporated under reduced pressure at 0 ° C. to remove methyl alcohol. Even in the process of distilling off methyl alcohol, almost no aggregation of particles was observed and it was stable, the average particle size was 0.4 μm, and the solid content concentration was 26%.
An aqueous emulsion dispersion of was obtained. It also has good storage stability, 4
In the 10-day storage test at 0 ° C, almost no aggregation was observed.

Then, this aqueous emulsion dispersion was applied to the primer-treated surface of a biaxially oriented polypropylene film (film thickness 20 μm) and dried and heat-treated at 110 ° C. for 5 minutes to obtain an oxygen barrier of the film (EVOH layer thickness 3 μm). -Gender 2
When measured under conditions of 0 ° C. and 0% RH, the oxygen permeation amount was ^2.5 cc / m ² · day · atm, which showed good barrier properties as a food packaging material (hereinafter, the oxygen permeation amount measurement condition). And the units are the same).

Comparative Examples 1 to 4 In Example 1, when the polyether-modified EVOH is not used and only the ordinary EVOH is dispersed (Comparative Example 1),
Further, in place of the above polyether-modified EVOH, an ordinary nonionic surfactant nonylphenyl ether with ethylene oxide (Comparative Example 2), an anionic surfactant sodium dodecylbenzenesulfonate (Comparative Example 3), or a polymer Saponification degree of 80 mol% as protective colloid,
Partially saponified polyvinyl alcohol having a degree of polymerization of 600 (Comparative Example 4) was used as a dispersion stabilizer, and other than that, Example 1 was used.
Attempts were made to disperse under the same conditions as above, but in each case, the solution that had been heated and dissolved was agitated and agglomerated at the stage of precipitation of particles, and a stable dispersion could not be obtained.

Thus, the polyether-modified EV of the present invention
It can be seen that OH has a remarkable effect on the dispersion stabilization of ordinary EVOH, which is a dispersoid, and a stable aqueous emulsion dispersion is obtained.

Example 2 An allyl ether containing an oxyethylene unit having a molecular weight of 750 and a oxypropylene unit having a double bond at the terminal in a molar ratio of 75:25 by the method of Production Example (b)-(a). (Unisafe PKA-50 manufactured by NOF CORPORATION)
11), ethylene and vinyl acetate are copolymerized and then saponified to give an EVOH component (A) having an ethylene content of 38 mol%, a saponification degree of 99.5 mol% and a polymerization degree of 900.
20 parts by weight of the polyether component (B) is graft-bonded to 100 parts by weight of the polyether-modified EVOH
A graft body was obtained.

50 parts of a mixed solvent solution of water / ethyl alcohol = 50/50 containing 10% of this polyether-modified EVOH graft product was used to obtain an ethylene content of 38 mol%, a saponification degree of 99.6 mol%, and a polymerization degree of 1100. EVOH
24 parts, 100 parts of ethyl alcohol and 100 parts of water were added and mixed, and dissolved by heating at 70 ° 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. Next, this dispersion was evaporated under reduced pressure at 15 ° C. with stirring to distill off ethyl alcohol. Even in the process of distilling off ethyl alcohol, there was almost no aggregation of particles and it was stable. The average particle size was 0.7 μm and the solid content was 22
% 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. A film (EVOH layer thickness 3 μm) coated, dried and heat-treated in the same manner as in Example 1 had an oxygen permeation amount of 3.5 and showed a good barrier property.

Example 3 In the same manner as in Example 1, 100 parts by weight of an EVOH component (A) having an ethylene content of 25 mol%, a saponification degree of 99.1 mol% and a polymerization degree of 1120 was used, and a polyamine having a molecular weight of 450 at its end was used. A polyether-modified EVOH block body was obtained in which 45 parts by weight of a polyether component (B) obtained by thiolation of oxyethylene allyl ether (Niox PKA-5003 manufactured by NOF CORPORATION) was bound in a block form via a sulfur atom. It was

100 parts of a mixed solvent solution of water / methyl alcohol = 60/40 containing 5% of this polyether-modified EVOH block was used, usually with an ethylene content of 26 mol%, a saponification degree of 99.8 mol% and a polymerization degree of 1050. EVOH
35 parts, 100 parts of methyl alcohol and 100 parts of water were added and mixed, and dissolved by heating 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 diameter was 0.6 μm. The dispersion is then stirred for 2
It was evaporated under reduced pressure at 0 ° C. to remove methyl alcohol. Even in the process of distilling off methyl alcohol, almost no aggregation of particles was observed and it was stable, the average particle size was 0.6 μm, and the solid content concentration was 23%.
An aqueous emulsion dispersion of was obtained. It also has good storage stability, 4
In the 10-day storage test at 0 ° C, almost no aggregation was observed. The oxygen permeation amount of the film (EVOH layer thickness 3 μm) coated, dried and heat-treated in the same manner as in Example 1 was 2.
No. 9 showed a good barrier property.

Example 4 EVOH having a thiol group at the end obtained by radical copolymerization of ethylene and vinyl acetate in the presence of thioacetic acid and then saponification by the method of Production Example (a)-(ii).
In the coexistence of polyoxyethylene allyl ether having a double bond at the terminal with a molecular weight of 400 (UNIOX PKA-5007 manufactured by NOF CORPORATION), an ethylene content of 44 mol% and a saponification degree of 99. Polyether-modified E in which 16 parts by weight of the polyether component (B) is block-bonded through a sulfur atom to 100 parts by weight of the EVOH component (A) having a polymerization degree of 670 and 7 mol%.
A VOH block was obtained.

Water containing 10% of this polyether modified EVOH block / isopropyl alcohol = 30 /
50 parts of a mixed solvent solution of 70 was added and mixed with 22 parts of ordinary EVOH having an ethylene content of 42 mol%, a saponification degree of 99.5 mol% and a polymerization degree of 1220, 100 parts of isopropyl alcohol and 100 parts of water, and dissolved by heating at 70 ° C. .

Next, this dispersion was evaporated under reduced pressure at 20 ° C. with stirring to remove isopropyl alcohol, and an aqueous emulsion dispersion having a solid content concentration of 21% was obtained. The average particle size of this aqueous dispersion was 0.8 μm, and there was almost no particle enlargement during the vacuum evaporation process, and a stable aqueous dispersion was obtained. Example 1
A film (EVO coated, dried and heat treated in the same manner as
The amount of oxygen permeation in the H layer (thickness: 3 μm) was 3.0, indicating good barrier properties.

Example 5 Polyoxyethylene allyl ether having a molecular weight of 1500 and having a double bond at the end (Unisafe PKA-501 manufactured by NOF CORPORATION) was manufactured by the method of manufacturing method (b)-(a).
0), ethylene and vinyl pivalate are copolymerized and then saponified to give a polyether component to 100 parts by weight of an EVOH component (A) having an ethylene content of 29 mol%, a saponification degree of 99.4 mol% and a polymerization degree of 800. (B) 2
3 parts by weight of graft-modified polyether-modified E
A VOH graft was obtained.

50 parts of a mixed solvent solution of water / methyl alcohol = 50/50 containing 10% of this polyether-modified EVOH graft product was used to obtain an ethylene content of 29 mol%, a saponification degree of 99.4 mol%, and a polymerization degree of 1300. EVOH
50 parts, 200 parts of methyl alcohol and 200 parts of water were added and mixed, and dissolved by heating at 70 ° C.

When this solution was cooled to 0 ° C. with stirring, particles were precipitated and a stable dispersion liquid was obtained. The average particle size was 0.5 μm. The dispersion is then stirred for 2
It was evaporated under reduced pressure at 0 ° C. to remove methyl alcohol. Even in the process of distilling off methyl alcohol, almost no aggregation of particles was observed and it was stable, the average particle diameter was 0.5 μm, and the solid content concentration was 23%.
An aqueous emulsion dispersion of was obtained. It also has good storage stability, 4
In the 10-day storage test at 0 ° C, almost no aggregation was observed. The oxygen permeation amount of the film (EVOH layer thickness 3 μm) coated, dried and heat-treated in the same manner as in Example 1 was 2.
No. 8 showed a good barrier property.

Example 6 50 parts of the polyether-modified EVOH described in Example 1 and 5 parts of sodium dodecylbenzenesulfonate were added and mixed to 500 parts of a mixed solvent of water / methyl alcohol = 50/50 and dissolved at 70 ° C. A high-speed stirrer was immersed in this solution and ordinary EVOH having an ethylene content of 35 mol%, a saponification degree of 99.7 mol% and a polymerization degree of 1000 was dissolved in a mixed solvent of water / methyl alcohol = 50/50 while stirring at 5000 rpm. When 5000 parts of a 10% solution was added dropwise, particles were precipitated to obtain a stable dispersion liquid. The average particle size was 0.9 μm.

Next, this dispersion liquid was evaporated under reduced pressure at 20 ° C. with stirring to distill off methyl alcohol to obtain a solid content concentration of 20%.
An aqueous emulsion dispersion of was obtained. The average particle size of this aqueous dispersion was 0.9 μm, and there was almost no particle enlargement during the vacuum evaporation process, and a stable aqueous dispersion was obtained. A film (EVOH layer thickness 3 μm) coated, dried and heat-treated in the same manner as in Example 1 had an oxygen permeation amount of 4.3 and showed a good barrier property.

[0068]

As described above, by using the dispersion stabilizer comprising the polyether-modified EVOH of the present invention, an aqueous dispersion having a high solid content concentration, which is excellent in stability during storage or use, particularly An aqueous emulsion dispersion is obtained, and since it is water-based, it has the advantage that there is no problem of environmental pollution, etc., and by coating and drying it can form a thin film with excellent gas barrier properties, aroma retention and oil / chemical resistance. It has high industrial value and can be used as a useful coating agent.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ken Moriya, 1621 Sakata, Kurashiki, Okayama Prefecture, Kuraray Co., Ltd.

Claims (2)

[Claims] 1. An ethylene-vinyl ester copolymer saponification component (A) and a polyether component (B) having an ethylene content of 10 to 70 mol% and a saponification degree of 80 mol% or more are bonded in a block or graft form. Dispersion stabilizer consisting of a copolymer. 2. 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 1.