JPH1180263A - Production of alcohol/water solution of ethylene-vinyl acetate copolymer saponificate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alcohol/water solution of an ethylene-vinyl acetate copolymer saponificate which can give a film having a good hue and reduced in the formation of fish eye by subjecting an ethylene/vinyl acetate copolymer to alkali saponification in an alcohol and adding water to the obtained alcoholic solution in the presence of an acid or an ester of an acid to convert it into an aqueous solution. SOLUTION: The ethylene-vinyl acetate copolymer desirably has an ethylene content of 15-60 mol.% and may contain copolymerizable ethylenically unsaturated monomers (e.g. propylene) in addition to ethylene and vinyl acetate. This copolymer in the form of a solution in e.g. methanol is saponified with e.g. sodium hydroxide in an amount of at most 0.05 equivalent per equivalent of the residual acetate groups. The concentration of the copolymer saponificate should be 10-55 wt.%. It is desirable that the degree of saponification is 80 mol.% or above. The acid used combinedly with the water is e.g. acetic acid. The ester used is exemplified by methyl formate and is desirably used in an amount of 0.01-50 equivalents per equivalent of the alkali added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ethylene-vinyl acetate copolymer pellet having good hue and little fisheye when formed into a film, for example, as a raw material for producing a wet-strand method. The present invention relates to a method for producing a vinyl acetate copolymer alcohol / water solution.

[0002]

2. Description of the Related Art Saponified ethylene-vinyl acetate copolymers are widely used in various applications such as films, sheets, containers and fibers because of their excellent properties such as oxygen barrier properties and mechanical strength. The saponified copolymer molded product is ethylene-
The saponified vinyl acetate copolymer is produced by melt-molding pellets.
A method of extruding a saponified vinyl acetate copolymer into a water / methanol solvent and cutting the same is disclosed in Japanese Patent Publication No. 47-38634.

[0003]

However, according to the technology disclosed in Japanese Patent Publication No. 47-38634, the saponified ethylene-vinyl acetate copolymer has a poor hue and the saponified ethylene-vinyl acetate copolymer. The film obtained from has the disadvantage that there are many fish eyes,
Therefore, a saponified ethylene-vinyl acetate copolymer having a good hue and a small fisheye of the film is desired.

[0004]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems. As a result, the ethylene-vinyl acetate copolymer was alkali-saponified in alcohol, and the obtained ethylene-vinyl acetate copolymer was obtained. In preparing a saponified ethylene-vinyl acetate copolymer / water solution by adding water to the polymer saponified alcohol solution, an acid or acid ester is allowed to coexist in the solution to prepare the saponified ethylene-vinyl acetate copolymer. By producing an alcohol / aqueous solution, the saponified ethylene-vinyl acetate copolymer (for example, obtained by precipitating the solution by a wet strand method) has been found to have the properties aimed at by the present invention. Was completed. In the present invention, when water is added to the alcohol solution of the saponified ethylene-vinyl acetate copolymer, it is preferable to add steam containing alcohol vapor, and when the method of the present invention is carried out industrially, a tower reactor is preferably used. , An alcohol solution of a saponified ethylene-vinyl acetate copolymer is introduced from the top of the column, alcohol vapor / steam is charged from the bottom of the column, alcohol is distilled from the top of the column, and an acid or acid ester is further introduced into the column. It is preferable to prepare.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The ethylene-vinyl acetate copolymer used in the present invention preferably has an ethylene content of 15 to 60 mol%, more preferably 20 to 55 mol%, more preferably 25 to 55 mol%.
50 mol%.

If the ethylene content is less than 15 mol%, when the saponified solution of the ethylene-vinyl acetate copolymer is precipitated in a coagulating solution, the precipitation is incomplete and emulsified, which is not preferable in terms of operation. In order to keep the alcohol solution of the vinyl copolymer in a homogeneous solution state,
Heating to a very high temperature is required, which is not preferable.
Further, when the saponified ethylene-vinyl acetate copolymer produced from the saponified ethylene-vinyl acetate copolymer / water solution obtained in the present invention is melt-molded, the melt-moldability and the oxygen barrier property under high humidity are obtained. Is undesirably reduced.

On the other hand, if it exceeds 60 mol%, the saponified ethylene-vinyl acetate copolymer obtained in the present invention
When a saponified ethylene-vinyl acetate copolymer produced from an aqueous solution is melt-molded, sufficient oxygen barrier properties cannot be obtained and mechanical strength is not easily improved, which is not preferable.

[0008] The ethylene-vinyl acetate copolymer of the present invention may contain, in addition to ethylene and vinyl acetate, an ethylenically unsaturated monomer copolymerizable therewith as a copolymerization component. Examples of the monomer include olefins such as propylene, isobutylene, α-octene, α-dodecene, and α-octadecene, acrylic acid, methacrylic acid,
Unsaturated acids such as crotonic acid, maleic acid, maleic anhydride, and itaconic acid or salts or mono- or dialkyl esters, etc., nitriles such as acrylonitrile, methacrylonitrile, amides such as acrylamide, methacrylamide, ethylenesulfonic acid, allyl Sulfonic acid, olefinsulfonic acid such as methallylsulfonic acid or a salt thereof, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallylvinylketone, N-vinylpyrrolidone, vinyl chloride,
Polyoxyalkylene (meth) allyl ethers such as vinylidene chloride, polyoxyethylene (meth) allyl ether, and polyoxypropylene (meth) allyl ether; polyoxyethylenes such as polyoxyethylene (meth) acrylate and polyoxypropylene (meth) acrylate Alkylene (meth) acrylate, polyoxyethylene (meth)
Polyoxyalkylene (meth) acrylamide such as acrylamide, polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, poly Oxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine and the like can be mentioned.

In the saponification reaction of the ethylene-vinyl acetate copolymer, it is necessary to perform saponification with an alcohol solvent. The alcohol used at this time includes methanol, ethanol, n-propanol, isopropanol, and the like. Examples thereof include n-butanol and t-butanol, and preferably methanol, n-propanol and t-butanol.
Butanol is used. Further, aliphatic polyhydric alcohols such as glycerin, ethylene glycol and hexanediol may be used together with the alcohol.

As the alkali, a conventionally known alkali used in an alkali saponification reaction of polyvinyl acetate or an ethylene-vinyl acetate copolymer can be used as it is. Specifically, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkali metal alcoholates such as sodium methylate and potassium t-butoxy, and 1,8-diazabicyclo [5,4,10] Examples thereof include cobasic amines represented by undecene-7 (DBU), and further, alkali metal carbonates and alkali metal hydrogencarbonates. Of these, sodium hydroxide is preferably used in terms of ease of handling and cost.

The amount of the alkali used varies depending on the required degree of saponification, the reaction temperature and the like, but it is used in an amount of 0.05 equivalent or less, preferably 0.03 equivalent based on the residual acetic acid groups in the ethylene-vinyl acetate copolymer. It is as follows.

In the saponification, the ethylene-vinyl acetate copolymer is dissolved in an alcohol or an alcohol-containing medium so as to have a concentration of usually about 20 to 60% by weight, and an alkali is added. React at temperature. The concentration of the saponified ethylene-vinyl acetate copolymer is not particularly limited as long as the saponified ethylene-vinyl acetate copolymer is not precipitated at the solution temperature, but usually the concentration of the saponified ethylene-vinyl acetate copolymer is 10 to 55% by weight. %, Preferably 15 to 50% by weight.

The saponification degree of the vinyl acetate component of the saponified ethylene-vinyl acetate copolymer obtained by the saponification is preferably at least 70 mol%, more preferably at least 80 mol%. When the saponification degree is less than 70 mol%, the thermal stability when the ethylene-vinyl acetate copolymer saponified product produced from the saponified ethylene-vinyl acetate copolymer / water solution obtained by the present invention is melt-molded. However, it is not preferable because sufficient oxygen barrier properties and mechanical strength cannot be obtained.

In the present invention, after the saponification of the ethylene-vinyl acetate copolymer is completed and an alcohol solution of a saponified ethylene-vinyl acetate copolymer having a desired degree of saponification is obtained, water is added to the alcohol solution. In addition, in preparing the saponified ethylene-vinyl acetate copolymer alcohol / aqueous solution, the most characteristic feature is that an acid or an ester of an acid coexists in the solution.

As the acid used, formic acid, acetic acid, propionic acid, acetoacetic acid, lactic acid, butyric acid and the like are used, and formic acid, acetic acid and acetoacetic acid are preferably used. Examples of acid esters include methyl formate, ethyl formate, methyl acetate,
Ethyl acetate, methyl propionate, ethyl propionate, methyl acetoacetate, ethyl acetoacetate and the like are used, and preferably methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate are used.

The amount of the acid or acid ester to be added is 0.01 to 5 with respect to the amount of alkali used for saponification.
0 equivalents, preferably 0.05 to 30 equivalents. If the corresponding amount is less than 0.01, the saponification degree of the obtained saponified ethylene-vinyl acetate copolymer gradually increases during the production process, and it is difficult to control the saponification degree.
If the saponified vinyl acetate copolymer has a poor hue, if it exceeds 50 equivalents, an acid or an acid ester tends to remain in excess, and if the saponified ethylene-vinyl acetate copolymer is melt-molded, It is not preferable because it is easy to do.

Hereinafter, the preferred production method of the present invention will be described in detail. First, the saponified ethylene-vinyl acetate copolymer solution is alkali-saponified, and water is added to the resulting saponified ethylene-vinyl acetate copolymer alcohol solution. The amount is preferably 3 to 500 parts by weight, more preferably 5 to 32 parts by weight, based on 100 parts by weight of the saponified copolymer.
0 parts by weight. If the amount of water is less than 3 parts by weight, the saponified ethylene-vinyl acetate copolymer / aqueous solution will not be uniform and will be unstable. -Saponified vinyl acetate copolymer in alcohol / water solution, the saponified product is precipitated, and it is difficult to extrude it into strands, which is not preferable. The water is preferably added as a mixture of alcohol vapor and steam, and the ratio (weight ratio) of alcohol vapor to steam is 95/50 to 20/8.
0 is preferable, and 90/10 to 25/75 is more preferable. If the weight ratio exceeds 95/5, the alcohol / water solution of the saponified product becomes non-uniform, which is not preferable.
If it is less than 80, the solution viscosity of the saponified ethylene-vinyl acetate copolymer / aqueous solution is high and unstable, and the precipitation of the saponified product is liable to occur.

The method of charging the alcohol vapor and the steam is not particularly limited, and may be charged separately or as alcohol / water mixed vapor.

Industrially, a tower reactor is used, and the charging of the alcohol vapor may be carried out at any of the top, the top, the middle, the bottom and the bottom of the tower, preferably the middle and the bottom of the tower. The steam may be charged at the top of the tower, at the top of the tower, at the middle of the tower, at the bottom of the tower, or at the bottom of the tower, but preferably at the middle of the tower, at the bottom of the tower, or at the bottom of the tower.

When the alcohol vapor and the steam are separately charged, it is preferable that the alcohol vapor and the steam flow in the same direction.

The method for coexisting an acid or an acid ester is not particularly limited, but ethylene-
A method of coexisting in an alcohol solution of a saponified vinyl acetate copolymer, a method of preparing an alcohol / water solution of a saponified ethylene-vinyl acetate copolymer, batch charging, split charging, and dropping of an acid or acid ester into a reactor (tower). A method of mixing and coexisting by charging at a constant rate, and a method of kneading an acid or an ester of an acid with water in an adjusted alcohol / water solution of a saponified ethylene-vinyl acetate copolymer to cause coexistence, are preferred. The charging at this time may be any of the top of the tower, the middle of the tower, the bottom of the tower, and the bottom of the tower, but it is preferable to perform the charging at a constant speed from the middle of the tower or the bottom of the tower.

The form of addition (preparation) for coexistence may be either liquid or gas.

According to the method of the present invention, an alcohol / aqueous solution of a saponified ethylene-vinyl acetate copolymer is obtained, and the concentration of the saponified product in the solution is preferably 10%.
To 55% by weight, more preferably 15 to 50% by weight.
It is. If the amount is less than 10% by weight, coagulation in a coagulating liquid becomes difficult, while if it exceeds 55% by weight, the porosity of the pellets is reduced, which adversely affects the thermal stability during molding.

In adjusting the concentration of the saponified substance,
Of course, it is adjusted by the amount of water or water / alcohol added, but it is also possible to adjust the alcohol content before and after the addition, and it is preferable to distill off the alcohol after the addition, more preferably, the alcohol. Steam / water vapor is introduced to distill off the alcohol.

When the alcohol is distilled off, the weight mixture ratio of the alcohol and water in the saponified alcohol / water solution is 9
It is preferably adjusted to 5/5 to 20/80, more preferably 9
0/10 to 25/75. If the weight ratio of alcohol and water exceeds 95/5, the alcohol / aqueous solution becomes unstable and strand precipitation may not be performed stably. If the ratio is less than 20/80, the solution viscosity of the alcohol / water solution is high, and This is not preferable because it may cause precipitation of the compound and make it difficult to extrude the strand.

Simultaneously with the addition of the acid or acid ester, saturated aliphatic amide (eg, stearic acid amide), unsaturated fatty acid amide (eg, olefinic acid amide), bisfatty acid amide (eg, ethylene bisstearic acid amide) Lubricants such as fatty acid metal salts (such as calcium stearate) and low molecular weight polyolefins (such as low molecular weight polyethylene having a molecular weight of about 500 to 10,000,
Or, a low molecular weight polypropylene or the like), an inorganic salt (for example, hydrotalcite or the like), a plasticizer (for example, an aliphatic polyhydric alcohol such as ethylene glycol, glycerin, or hexanediol) may be blended.

Thus, an alcohol / aqueous solution of a saponified ethylene-vinyl acetate copolymer is obtained by the method of the present invention. To obtain a saponified ethylene-vinyl acetate copolymer (polymer) from the solution, the solution Is preferably extruded and precipitated in a coagulating liquid in the form of a strand. Water or a water / alcohol mixed solvent is used as the coagulating liquid,
The alcohol concentration when alcohol is used is preferably equal to or lower than the alcohol content of the alcohol / water mixture in the copolymer saponified alcohol / aqueous solution. It is not preferable because the polymer loss increases.

Further, the coagulating liquid has a boiling point of 100 ° C. or less and is compatible with alcohol.
It is also possible to use an organic solvent which does not dissolve the saponified vinyl acetate copolymer. Examples of the organic solvent include aromatic hydrocarbons such as benzene, ketones such as acetone and methyl ethyl ketone, ethers such as dipropyl ether, and organic acid esters such as methyl acetate, ethyl acetate and methyl propionate. The temperature at which the saponified ethylene-vinyl acetate copolymer solution is brought into contact with the coagulating solution is -1.
The temperature is 0 to 40 ° C, preferably 0 to 20 ° C. Since the above organic solvent is a non-solvent of the saponified product, there is almost no fear that the saponified product dissolves in the coagulation liquid to cause polymer loss,
Operation at as low a temperature as possible is safe.

The saponified ethylene-vinyl acetate copolymer solution is extruded into a coagulating solution in a strand form from a nozzle or die having an arbitrary shape, usually a circular hole. As described above, the cross-sectional shape of the hole is generally circular, but may be elliptical, square, rhombic, star-shaped, or the like in some cases, and the diameter of the hole is 1 to 3.
About 5 mm is appropriate. The number of strands is not necessarily one, but can be extruded in an arbitrary number between several and several hundred.

The saponified ethylene-vinyl acetate copolymer extruded in the form of a strand is cut and pelletized after solidification has sufficiently proceeded.

The pellets obtained above are preferably subjected to a water washing treatment.
Rinse in a water bath at 0-50 ° C. By washing with water, excess acid in the saponified ethylene-vinyl acetate copolymer pellets,
Alternatively, acid esters, oligomers and the like are removed. The pellets obtained by the above treatment have a diameter of 2 to 5 mm and a length of 2 to 5 m in the case of a cylindrical shape from the viewpoint of workability and handling during molding.
m, and in the case of a spherical shape, those having a diameter of about 2 to 5 mm are practical.

The saponified ethylene-vinyl acetate copolymer pellets thus obtained are melt-molded and molded into a desired molded product. The temperature condition for melt molding is about 160 to 260 ° C. It is desirable.
At the time of molding, a known additive such as a reinforcing material such as glass fiber or carbon fiber, a filler, a coloring agent, a stabilizer such as hydrotalcite, a foaming agent, or a drying agent may be appropriately added as needed. The saponified ethylene-vinyl acetate copolymer may also contain a suitable amount of a modifying thermoplastic resin.

As the melt molding method, any molding method such as an injection molding method, a compression molding method, and an extrusion molding method can be adopted. Examples of the extrusion molding method include a T-die method, a hollow molding method, a pipe extrusion method, a linear extrusion method, a deformed die extrusion method, an inflation method and the like, and a molding of a saponified ethylene-vinyl acetate copolymer alone. Objects (films, sheets, tapes,
Bottles, pipes, filaments, extruded shaped sections, etc.)
In addition, coextrusion molding of the saponified ethylene-vinyl acetate copolymer layer and another thermoplastic resin layer is also possible.

In the case of coextrusion molding, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-α-olefin (α-olefin having 3 to 20 carbon atoms) may be used as the mating resin.
Olefin) copolymer, ethylene-acrylate copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, homo- or copolymer of olefin such as polypentene, Alternatively, polyolefin resins in a broad sense, such as those obtained by graft-modifying a homo- or copolymer of these olefins with an unsaturated carboxylic acid or an ester thereof, polyester,
Examples include polyamide, copolymerized polyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, styrene resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, and chlorinated polypropylene. Also different ethylene
Coextrusion with a saponified vinyl acetate copolymer is also possible.

Further, a molded product such as a film or a sheet is once obtained from a saponified ethylene-vinyl acetate copolymer, and this is extrusion-coated with another thermoplastic resin such as a polyolefin, or a film or sheet of another thermoplastic resin. When laminating with an adhesive, any substrate (paper, metal foil, stretched or unstretched plastic film or sheet, woven fabric, nonwoven fabric, metal foil, woody surface, etc.)
It is also possible to coat with a saponified vinyl acetate copolymer by extrusion coating (furthermore, another resin, for example, a heat-sealing resin may be extrusion-coated).

It is to be noted that a molded product after melt molding, a co-extruded molded product,
Melt coat molded products can be heat-treated, cooled, rolled, uniaxially or biaxially stretched, printed, dry laminated, solution or melt-coated, bag-formed, deep-drawn, boxed, tubed, if necessary. Split processing or the like can be performed.

[0037]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 A methanol solution containing an ethylene content of 35 mol% and an ethylene-vinyl acetate copolymer of 50% was supplied at a rate of 10 kg / h to the upper part of a tray column (saponification column). A methanol solution containing 0.012 equivalents of sodium hydroxide was supplied from the top of the column to the residual acetic acid groups in the coalescence.
On the other hand, methanol was supplied from the lower part of the tower at a rate of 15 kg / hour.
The tower temperature is 100-110 ° C and the tower pressure is 3 kg / cm ² G
Met. A methanol solution of a saponified ethylene-vinyl acetate copolymer was taken out from 30 minutes after the start of the charging, and the composition was 30% saponified ethylene-vinyl acetate copolymer and 70% methanol, and saponified ethylene-vinyl acetate copolymer. Of the vinyl acetate component was 99.0 mol%.

Next, the obtained methanol solution of the saponified ethylene-vinyl acetate copolymer is supplied at a rate of 10 kg / hour from the upper portion of the methanol / aqueous solution adjusting tower, 4 kg / hour of methanol vapor at 120 ° C., and 2. Charge from the bottom of the tower at a rate of 5 kg / h, and add 8 k of methanol from the top of the tower.
g / h, and at the same time, 6 equivalents of methyl acetate with respect to the amount of sodium hydroxide used in the saponification were added to the column at a temperature of 95 to 95%.
A 110 ° C tower was charged from the center of the tower and ethylene-
Saponified vinyl acetate copolymer / water solution (resin concentration 35
%).

The saponified ethylene-vinyl acetate copolymer alcohol / water solution obtained above was evaluated as follows. (1) Hue of pellet ○: No coloring △: Colored slightly yellow visually ×: Colored yellow visually

The resulting saponified ethylene-vinyl acetate copolymer alcohol / water solution was extruded from a nozzle having a pore diameter of 4 mm into a coagulating solution tank containing 5% methanol and 95% water and maintained at 5 ° C. in the form of a strand. After the solidification,
The strand is cut with a cutter, and has a diameter of 3.8 mm.
A pellet having a length of 4 mm was obtained and evaluated according to the following criteria.

(2) Performance of Film The obtained pellet was formed into a film under the following conditions, and the fish eye of the obtained film was evaluated as follows. (Film formation conditions)

(Measurement Conditions of Fish Eye) Film 1
The number of fish eyes per 00 cm ² was measured.・ ・ ・: 1 or less ○: 2 to 5 or less Δ: 6 to 9 or less ×: 10 or more The results are shown in Table 1.

Example 2 Example 2 was repeated except that acetic acid (6 equivalents to the amount of sodium hydroxide) was used in place of methyl acetate.
Evaluation was performed in the same manner as in Example 1.

Example 3 An evaluation was performed in the same manner as in Example 1 except that the amount of sodium hydroxide was changed to 0.004 equivalent.

Example 4 The procedure of Example 1 was repeated, except that an ethylene-vinyl acetate copolymer having an ethylene content of 31 mol% was charged in the upper part of the tray column (saponification tower) according to Example 1. Example 1
Was evaluated in the same way as

Comparative Example 1 The procedure of Example 1 was repeated, except that the addition of methyl acetate was omitted, and the evaluation was performed in the same manner as in Example 1. The evaluation results of Examples 2 to 4 and Comparative Example 1 are shown in Table 1.

[0048]

Table 1 Ethylene content Pellets Pellets Film performance (mol%) Saponification hue (fish eye) degree (mol%) of film Example 1 35 99.0 ○ Example 2 35 99.0 ◎ Example 3 35 97.8 Example 4 31 99.2 ○ ○ Comparative Example 1 35 99.5 × ×

[0049]

According to the present invention, an ethylene-vinyl acetate copolymer is alkali-saponified in alcohol, and water is added to the obtained alcohol solution of the saponified ethylene-vinyl acetate copolymer to form an ethylene-vinyl acetate copolymer. In preparing the saponified alcohol / water solution, an acid or an ester of an acid coexists in the solution, so that the saponified ethylene-vinyl acetate copolymer obtained from the saponified ethylene-vinyl acetate copolymer / water solution Has good hue, and the film obtained from the saponified product has few fish eyes.

[Procedure amendment]

[Submission date] April 24, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

As the alkali, a conventionally known alkali used in an alkali saponification reaction of polyvinyl acetate or an ethylene-vinyl acetate copolymer can be used as it is. Specifically, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkali metal alcoholates such as sodium methylate and potassium t-butoxy, and 1,8-diazabicyclo [5,4,10] strongly basic amines typified by undecene -7 (DBU), further it is an alkali metal carbonate, and the like alkali metal bicarbonate is ease of handling, the use of sodium hydroxide from the cost and the like are preferable.

Claims (5)

[Claims] An alcohol-saponified ethylene-vinyl acetate copolymer is obtained by alkali saponifying an ethylene-vinyl acetate copolymer in an alcohol, and adding water to the obtained alcohol solution of the saponified ethylene-vinyl acetate copolymer. A method for producing an alcohol / aqueous solution of a saponified ethylene-vinyl acetate copolymer, which comprises coexisting an acid or an ester of an acid in the solution when preparing the aqueous solution. 2. An ethylene-vinyl acetate copolymer obtained by alkali saponifying an ethylene-vinyl acetate copolymer in an alcohol, and adding alcohol vapor / water vapor to the obtained saponified ethylene-vinyl acetate copolymer solution. A method for producing a saponified ethylene-vinyl acetate copolymer / aqueous solution, characterized in that an acid or an ester of an acid is coexistent in preparing the saponified alcohol / aqueous solution. 3. An alkali saponification of an ethylene-vinyl acetate copolymer in an alcohol, followed by introducing a saponified ethylene-vinyl acetate copolymer solution from the top of the tower using a tower reactor, and from the bottom of the tower. Ethylene-acetic acid is prepared by charging alcohol vapor / steam and distilling alcohol from the top of the tower to prepare a saponified ethylene-vinyl acetate copolymer solution, wherein an acid or acid ester is charged into the tower. Method for producing saponified vinyl copolymer alcohol / water solution. 4. The method for producing an alcohol / aqueous solution of a saponified ethylene-vinyl acetate copolymer according to claim 1, wherein any one of formic acid, acetic acid and acetoacetic acid is used as the acid. . 5. The method according to claim 1, wherein as the acid ester, any one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl propionate and ethyl propionate is used. Production method of saponified ethylene-vinyl acetate copolymer alcohol / water solution.