JP3602677B2 - Saponified ethylene-vinyl ester copolymer composition and method for producing the same - Google Patents

Description

【００４０】
【発明の効果】
着色が少なく、溶融成形時にブツの発生が少ないエチレン−ビニルエステル共重合体ケン化物組成物を提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-quality saponified ethylene-vinyl ester copolymer composition having little coloring and little occurrence of bumps during melt molding, and a method for producing the same.
[0002]
[Prior art]
Saponified ethylene-vinyl ester copolymer is a useful polymer material excellent in oxygen shielding property, oil resistance, non-charging property, mechanical strength and the like, and is widely used as various packaging materials such as films, sheets and containers. When the saponified ethylene-vinyl ester copolymer is used as various packaging materials, not only performance for the intended use but also slight coloring in appearance, fish eyes, spots, rough skin, and transparency are regarded as problems.
[0003]
However, the saponified ethylene-vinyl ester copolymer has a problem in that it tends to cause problems such as coloring and blemishes during melt molding. Therefore, conventionally, the following various methods have been proposed as methods for suppressing the occurrence of coloring and blemishes.
[0004]
For example, methods for adding an acid such as acetic acid or phosphoric acid and / or a salt thereof to a saponified ethylene-vinyl ester copolymer are described in JP-A-48-25048, JP-A-51-26993, and JP-A-51-26993. -28891, JP-A-51-49294, JP-A-51-91988, JP-A-52-954, JP-A-52-955, JP-A-52-956, JP-A-56-20044, JP-A-56-20044. Many applications have been filed, such as 41204, JP-A-61-95053, JP-A-61-95054, and JP-A-62-143954. That is, the ethylene-vinyl ester copolymer is saponified by adding caustic alkali, washed with water, and then an acid such as acetic acid or phosphoric acid and / or a salt thereof is added. It is said that a product with less occurrence can be obtained.
[0005]
[Problems to be solved by the invention]
As described above, various countermeasures have been taken against problems such as coloring and occurrence of bumps in the saponified ethylene-vinyl ester copolymer.
However, regarding the method of adding an acid such as acetic acid and phosphoric acid and / or a salt thereof to the saponified ethylene-vinyl ester copolymer, neutralization and washing after saponification are not sufficient, If the amount of addition of these salts is not appropriate, the occurrence of coloring and lumps tends to increase. In order to remedy this drawback, sufficient washing after saponification and optimization of the amount of an acid such as acetic acid and phosphoric acid and / or a salt thereof have been carried out. Is not yet reached.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a saponified ethylene-vinyl ester copolymer composition having less coloring and less occurrence of bumps during melt molding, and a method for producing the same.
[0007]
[Means for Solving the Problems]
The above object is achieved by providing a saponified ethylene-vinyl ester copolymer composition containing 1 to 5000 ppm of sulfite and / or bisulfite in terms of sulfurous acid. In addition, a saponified ethylene-vinyl ester copolymer composition containing an acid having a pKa at 25 ° C of 2 to 6 and / or a metal salt thereof in an amount of 10 to 5000 ppm in terms of acid at 25 ° C is more sufficiently achieved. Is done.
Also, by providing a method for producing a saponified ethylene-vinyl ester copolymer composition, characterized by immersing a saponified ethylene-vinyl ester copolymer in an aqueous solution containing sulfite and / or bisulfite. And (2) an aqueous solution containing an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof in an aqueous solution containing a sulfite and / or a hydrogen sulfite, and a saponified ethylene-vinyl ester copolymer. This is more sufficiently achieved by providing a method for producing a saponified ethylene-vinyl ester copolymer composition characterized by immersion.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The sulfite and / or bisulfite referred to in the present invention refer to compounds represented by Mx (SO ₃ ) y and Mx (HSO ₃ ) y, respectively, where M is a compound capable of dissociating into a cation in water. There is no particular limitation. Specific examples of the sulfite include potassium sulfite, sodium sulfite, magnesium sulfite, calcium sulfite, and ammonium sulfite, and specific examples of the bisulfite include potassium bisulfite, sodium hydrogen sulfite, and the like. Among them, sodium salts (sodium sulfite, sodium hydrogen sulfite) have been approved by the FDA as food additives and are excellent in safety. Therefore, EVOH is also preferable from the viewpoint of being frequently used as a material for food packaging containers.
[0009]
The content of the sulfite and / or bisulfite is 1 to 5000 ppm in terms of sulfurous acid. Here, the conversion to sulfurous acid means that when M is H (hydrogen) in the formulas of Mx (SO ₃ ) y and Mx (HSO ₃ ) y, that is, weight conversion in H ₂ SO ₃ . When it is less than 1 ppm, the effect of improving coloring and melt stability is poor, and when it exceeds 5,000 ppm, the problem of coloring tends to occur. The content of the sulfite and / or bisulfite is preferably 10 ppm or more, more preferably 20 ppm or more. Further, it is preferably at most 1000 ppm, more preferably at most 500 ppm.
[0010]
The acid and / or metal salt thereof used in the present invention is an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof. Here, pKa means a value defined by pKa = -logKa, where Ka is the dissociation constant of the acid. When the acid is a polybasic acid, it may have at least one acid group having a pKa of 2 to 6. It is important that the pKa is 2 to 6, and when the pKa is 2 or less or 6 or more, the effect of reducing the occurrence of coloring and the occurrence of bumps during melt molding decreases, and it is difficult to sufficiently achieve the object. The value of pKa is more preferably 3 to 5.5. Various inorganic acids and organic acids can be used as the acid having a pKa of 2 to 6, and are not particularly limited. Specific examples thereof include phosphoric acid, phosphorous acid, acetic acid, oxalic acid, and succinic acid. , Adipic acid, tartaric acid, citric acid and the like. Further, it is desirable that the acid has a boiling point of 115 ° C. or higher for the purpose of preventing volatilization of the acid and the like when the chip is dried after the treatment.
[0011]
Examples of metal salts of these acids include, but are not limited to, sodium salts, potassium salts, lithium salts, magnesium salts, calcium salts, barium salts and the like, and sodium acetate, potassium acetate, calcium acetate and the like. Can be used. When a polybasic acid is used, its metal salt may be a partial salt, and sodium dihydrogen phosphate or potassium dihydrogen phosphate can also be used.
[0012]
The content of an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof is preferably 10 to 5000 ppm in terms of acid. Here, the acid conversion means weight conversion as an acid that is neither a salt nor an ion. If it is less than 10 ppm, the effect of improving coloring and melt stability is not sufficient, and if it exceeds 5000 ppm, the problem of coloring tends to occur. The content of the acid having a pKa of 2 to 6 and / or a metal salt thereof at 25 ° C is more preferably 20 ppm or more, and particularly preferably 50 ppm or more. Further, it is more preferably at most 1,000 ppm, particularly preferably at most 500 ppm.
[0013]
The ethylene-vinyl ester copolymer used in the present invention is obtained by copolymerizing ethylene and vinyl ester, but the type of vinyl ester is not particularly limited. Examples thereof include aliphatic vinyl esters such as vinyl acetate, vinyl propionate, vinyl versatate, and vinyl pivalate, and may be vinyl esters of aromatic carboxylic acids. Among these vinyl esters, vinyl acetate is preferred from the viewpoint of cost.
[0014]
The saponified ethylene-vinyl ester copolymer obtained in the present invention has an ethylene content of 10 to 60 mol%, preferably 20 to 55 mol%, and a saponification degree of the vinyl ester component of 90 mol% or more, preferably 95 mol. % Or more. When the ethylene content is 10 mol% or less, the oxygen barrier property at high humidity decreases, while when the ethylene content is 60 mol% or more, physical properties such as sufficient oxygen barrier property and printability deteriorate. On the other hand, when the saponification degree is 90 mol% or less, oxygen barrier properties and moisture resistance are reduced.
[0015]
Hereinafter, the manufacturing method will be specifically described. The polymerization of ethylene and vinyl ester is not limited to solution polymerization, and may be a continuous type or a batch type. For example, the polymerization conditions in the case of batch type solution polymerization are as follows.
[0016]
Solvent: Alcohols are preferable, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl ester and ethylene-vinyl ester copolymer can be used. As the alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.
Catalyst: 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (4-methyl-2,4-dimethylvaleronitrile) ), Azonitrile initiators such as 2,2'-azobis- (2-cyclopropylpropionitrile) and isobutyryl peroxide, cumyl peroxy neodecanoate, diisopropyl peroxy carbonate, di-n-propyl peroxy Organic peroxide initiators such as dicarbonate, t-butylperoxy neodecanoate, lauroyl peroxide, benzoyl peroxide, and t-butyl hydroperoxide can be used.
Temperature: 20-90C, preferably 40-70C.
Time; 2 to 15 hours, preferably 3 to 11 hours.
Polymerization rate: 10 to 90%, preferably 30 to 80%, based on the charged vinyl ester.
Resin content in solution after polymerization; 5 to 85%, preferably 20 to 70%.
Ethylene content in the copolymer: 20 to 60 mol%, preferably 25 to 55 mol%.
[0017]
In addition, other than ethylene and vinyl ester, monomers copolymerizable therewith, for example, α-olefins such as propylene, isobutylene, α-octene, α-dodecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid, itacone Unsaturated acids such as acids or anhydrides, salts or mono- or dialkyl esters thereof; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfone An olefin sulfonic acid such as an acid or a salt thereof; alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like can be coexisted in a small amount.
[0018]
After the polymerization for a predetermined time, after reaching a predetermined polymerization rate, if necessary, a polymerization inhibitor is added, unreacted ethylene gas is removed by evaporation, and then unreacted vinyl ester is expelled. As a method of driving out unreacted vinyl ester from the ethylene-vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously supplied at a constant rate from the top of a column filled with Raschig rings, An organic solvent vapor such as methanol is blown from the bottom, a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester is discharged from the top of the tower, and the copolymer solution from which the unreacted vinyl ester is removed from the bottom of the tower is taken out. Adopted.
[0019]
An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester component in the copolymer. The saponification method can be either a continuous type or a batch type. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate and the like are used. For example, the saponification conditions in the case of the batch system are as follows.
Concentration of the copolymer solution; 10 to 50%.
Reaction temperature;
Amount of catalyst used: 0.02 to 0.6 equivalent (per vinyl ester component).
Time; 1-6 hours.
Although the degree of saponification after the saponification reaction varies depending on the purpose, it is usually at least 90%, preferably at least 95% of the vinyl ester component. The saponification degree can be arbitrarily adjusted depending on the conditions.
[0020]
Since the saponified ethylene-vinyl ester copolymer after the reaction contains an alkali catalyst, by-product salts, and other impurities, they are removed by neutralization and washing as necessary.
[0021]
The method of causing the obtained saponified ethylene-vinyl ester copolymer to contain a sulfite and / or a hydrogen sulfite is not particularly limited. For example, a method of immersing the saponified product in a solution in which sulfite and / or bisulfite is dissolved, a method of melting the saponified product and mixing the sulfite and / or bisulfite, or There is a method of dissolving in a suitable solvent and mixing a sulfite and / or a bisulfite.
[0022]
Among these methods, it is possible to prevent deterioration of the resin caused by melting and to contain a sulfite and / or bisulfite by immersing the resin in the solution because it is not necessary to recover the solvent from the resin solution. The preferred method is This processing can be performed by either a batch method or a continuous method. In this case, the shape of the saponified product may be any shape such as powder, granule, sphere, and columnar chip.
[0023]
When the saponified ethylene-vinyl ester copolymer is immersed in a sulfite and / or bisulfite solution, the concentration of the sulfite and / or bisulfite is preferably in the range of 0.0001 to 100 g / L, Most preferably, it is 0.001 to 20 g / L. The solvent of the solution to be immersed is not particularly limited, but is preferably an aqueous solution from the viewpoint of handling and the solubility of sulfite and / or bisulfite. When the saponified product is immersed, the weight of the solution of the sulfite and / or the bisulfite is preferably at least three times, preferably at least 20 times the weight of the saponified product when dried. The suitable range of the immersion time varies depending on the form of the saponified ethylene-vinyl ester copolymer, but is preferably 1 hour or more, preferably 2 hours or more in the case of a chip of about 1 to 10 mm.
[0024]
In addition to containing a sulfite and / or a hydrogen sulfite in the saponified ethylene-vinyl ester copolymer, an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof is added to form a molded product. The occurrence of bumps and coloring at the time can be more effectively reduced.
[0025]
The treatment method is not particularly limited as in the case of the treatment with the sulfite and / or the bisulfite. For example, a method of immersing the saponified product in a solution of an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof, melting the saponified product and having an acid and a pKa of 2 to 6 at 25 ° C. Alternatively, there is a method of mixing a metal salt of an acid, or a method of dissolving the saponified product in an appropriate solvent and mixing an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt of an acid.
[0026]
Among these methods, degradation of the resin caused by melting can be prevented, and it is not necessary to recover the solvent from the resin solution. And / or a method of immersion in a solution of a metal salt of an acid, particularly an aqueous solution, and the concentration is preferably 0.01 to 50 g / L, more preferably 0.05 to 20 g / L, as the total value of the acid and the metal salt. L. This processing can also be performed by either a batch method or a continuous method. The shape of the saponified product may be any shape such as powder, granule, sphere, and columnar chip.
[0027]
The treatment with an acid having a pKa of 2 to 6 and / or a metal salt thereof at 25 ° C. may be performed before or after the treatment with a sulfite and / or a bisulfite. They may be processed at the same time.
Of these, treatment with a solution containing both an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof, and a sulfite and / or a bisulfite is preferred from the viewpoint of simplification of the process. At this time, it is desirable that the pH of the treatment liquid is adjusted to 7 or less, more preferably 6.2 or less, in order to more effectively suppress occurrence of spots and coloring during melt molding.
[0028]
When treated by immersion in a sulfite and / or bisulfite solution as described above, the saponified ethylene-vinyl ester copolymer composition containing the desired sulfite and / or bisulfite is finally dried. Things are obtained. In addition, in the case of treating by immersion in a solution of an acid having a pKa of 2 to 6 and / or a metal salt thereof at 25 ° C., the sulphate and / or bisulfite of interest is finally dried. An saponified ethylene-vinyl ester copolymer composition containing an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof is obtained.
[0029]
Suitable melt index (MI) of the saponified ethylene-vinyl ester copolymer used in the present invention (measured at 190 ° C. under a load of 2160 g; The temperature was measured at a plurality of temperatures as described above, and the reciprocal of the absolute temperature was plotted on the semi-logarithmic graph on the horizontal axis, and the melt index was plotted on the vertical axis (logarithm), and the value extrapolated to 190 ° C. was 0.1 to 200 g / 10 min. , Optimally 0.2 to 100 g / 10 min. It is.
[0030]
The composition of the sulfite and / or bisulfite and the saponified ethylene-vinyl ester copolymer obtained by the method as described above is melt-molded into various molded products such as films, sheets, containers, pipes, and fibers. Molded. These molded products can be crushed and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers and the like. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding. The melting temperature varies depending on the melting point of the copolymer and the like, but is preferably about 150 to 270 ° C. It is also possible to blend two or more copolymers having different degrees of polymerization, ethylene content and saponification degree of the composition of the saponified copolymer and melt-mold. In addition, the composition of the saponified copolymer may contain other various plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, slip agents, antistatic agents, drying agents, crosslinking agents such as boric acid, metals. It is also possible to add an appropriate amount of a salt, a filler, a reinforcing agent such as various fibers, and the like. By such a method, a molded product with less coloring and lumps can be obtained.
[0031]
It is also possible to mix an appropriate amount of a thermoplastic resin other than the saponified copolymer composition. Examples of the thermoplastic resin include various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin having 4 or more carbon atoms, polyolefin Copolymer of ethylene and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylate ester copolymer, or modified polyolefin obtained by graft-modifying these with unsaturated carboxylic acid or a derivative thereof), various nylons (nylons) 6, nylon 66, nylon 6/66 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin. In addition, the composition of the saponified ethylene-vinyl ester copolymer in the present invention can be used as a multilayer structure by laminating, especially by co-extrusion, the thermoplastic resin. Further, the saponified ethylene-vinyl ester copolymer composition can be co-extruded or solution-coated on a base film such as paper, plastic film and metal foil.
[0032]
【Example】
Hereinafter, specific examples will be described. In addition, (part), (%), and (ppm) are expressed on a weight basis unless otherwise specified.
[0033]
Various evaluations in the following Examples were performed according to the following procedures.
The measurement of the content of the sulfite / bisulfite and the acid having a pKa of 2 to 6 at 25 ° C. and the salt thereof was carried out as follows.
10 g of a dry chip as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography, and the amount of sulfite ions was obtained in terms of sulfurous acid. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 2.5 mM sodium carbonate and 1.0 mM sodium hydrogen carbonate. In the determination, a calibration curve prepared with an aqueous solution of sodium sulfite was used. Similarly, the content of an acid having a pKa of 2 to 6 at 25 ° C. and its salt was obtained in terms of acid as the total amount of the acid and its salt. At this time, a calibration curve was prepared with acetic acid for acetate ions and phosphoric acid for phosphate ions.
[0034]
The yellowness of the obtained dried chips was measured according to JIS-K-7103. In addition, the yellowness of the melt-molded product was measured by melting the dried chip at 230 ° C. for 6 minutes and 30 seconds, and measuring the surface color of the plate-shaped product according to JIS-K-7103.
The dried saponified product was formed at a cylinder temperature of 230 ° C. using an extruder / T-die single layer film forming machine having a diameter of 20 mm to form a film having a thickness of 30 μm. The number of spots on the film was measured by counting the number of those visually observable.
[0035]
Example 1
19,600 parts of vinyl acetate, 2180 parts of methanol, and 7.5 parts of AIBN (azobisisobutyronitrile) were charged into a polymerization tank having a pressure resistance of 100 kg / cm ^2. The ethylene pressure was adjusted to 35.5 kg / cm ² . After maintaining the temperature and pressure for 3.5 hours for polymerization, 5 parts of hydroquinone was added, the polymerization tank was returned to normal pressure, and ethylene was removed by evaporation. Subsequently, this methanol solution was continuously allowed to flow down from the top of the effluent tower filled with Raschig rings, while methanol vapor was blown from the bottom of the tower to release unreacted vinyl acetate monomer together with methanol vapor from the top of the tower and passed through a condenser. By removing, a 45% methanol solution of ethylene-vinyl acetate copolymer having 0.01% or less of unreacted vinyl acetate was obtained. At this time, the polymerization rate was 47% based on the charged vinyl acetate, and the ethylene content was 33% by mole.
[0036]
Next, a methanol solution of the ethylene-vinyl acetate copolymer was charged into a saponification reactor, and a sodium hydroxide / methanol solution (80 g / L) was adjusted to 0.4 equivalent to the vinyl acetate component in the copolymer. Then, methanol was added to adjust the copolymer concentration to 20%. The temperature was raised to 60 ° C., and the reaction was performed for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, the reaction was stopped by neutralization with acetic acid, and the mixture was extruded into water from a metal plate having a circular opening to be precipitated, and cut to obtain a chip having a diameter of about 3 mm and a length of about 5 mm. The operation of removing the obtained chips by a centrifuge and further adding a large amount of water to remove the chips was repeated.
[0037]
3 kg of the hydrous chip of the saponified ethylene-vinyl ester copolymer thus obtained was immersed in 40 L of a 0.1 g / L aqueous solution of sodium sulfite at 25 ° C. for 4 hours. After immersion, drying was performed using a hot air drier at 80 ° C. for 3 hours and subsequently at 105 ° C. for 15 hours. The saponified ethylene-vinyl ester copolymer obtained had a saponification degree of 99.5 mol% and a melt index (at 190 ° C. under a load of 2160 g) of 2 g / 10 min. Met. The content of sulfite in the dried chips was 50 ppm in terms of sulfurous acid. The yellowness of the dried chips was 13, and the yellowness of the melt-formed product was 16. In addition, the number of bumps was 31 pieces / 100 cm ² . These results are shown in Table 1.
[0038]
Examples 2 to 9, Comparative Examples 1 to 5
In Example 1, a saponified ethylene-vinyl ester copolymer composition chip was obtained in the same manner as in Example 1 except that the chip was immersed in the following aqueous solution instead of the aqueous solution of 0.1 g / L sodium sulfite. And evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.
Comparative Example 1 pure water Comparative Example 2 0.01 g / L sodium sulfite aqueous solution Example 2 0.02 g / L sodium sulfite aqueous solution Example 3 1 g / L sodium sulfite Aqueous solution / Comparative example 3 ··· 20 g / L aqueous sodium sulfite solution · Example 4 ··· 0.1 g / L sodium hydrogen sulfite aqueous solution · Example 5 ··· 0.1 g / L potassium sulfite aqueous solution · Example 6 0.1 g / L aqueous solution of magnesium sulfite. Example 7: An aqueous solution containing 0.1 g / L of sodium sulfite and 0.5 g / L of acetic acid. Example 8: 0.1 g / L of sodium sulfite. Aqueous solution containing 0.5 g / L phosphoric acid ・ Example 9 ... Aqueous solution containing 0.1 g / L sodium sulfite, 0.5 g / L acetic acid and 0.2 g / L sodium acetate ・ Comparative example 4 ... 0.5 g / L acetic acid aqueous solution - an aqueous solution containing sodium acetate of acetic acid and 0.2 g / L Comparative Example 5 ...... 0.5g / L [0039]
[Table 1]

[0040]
【The invention's effect】
It is possible to provide a saponified ethylene-vinyl ester copolymer composition having little coloring and little occurrence of bumps during melt molding.

Claims (4)

A saponified ethylene-vinyl ester copolymer composition containing 1 to 5000 ppm of sulfite and / or bisulfite in terms of sulfurous acid. The saponified ethylene-vinyl ester copolymer composition according to claim 1, comprising an acid having a pKa at 25C of 2 to 6 and / or a metal salt thereof in an amount of 10 to 5000 ppm in terms of acid. A method for producing a saponified ethylene-vinyl ester copolymer composition, comprising immersing a saponified ethylene-vinyl ester copolymer in an aqueous solution containing sulfite and / or bisulfite. A saponified ethylene-vinyl ester copolymer is immersed in (1) an aqueous solution containing a sulfite and / or a bisulfite and (2) an aqueous solution containing an acid having a pKa of 2 to 6 at 25 ° C. and / or a metal salt thereof. A method for producing a saponified ethylene-vinyl ester copolymer composition.