JP2002121290A - Method for producing ethylene-vinyl alcohol copolymer hydrous composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an ethylene-vinyl alcohol copolymer hydrous composition through efficiently removing an alcohol out of the system without aggravating both the working environment and the ambience thereof, and to produce ethylene-vinyl alcohol pellets from the thus obtained composition stably and at a high rate of washing. SOLUTION: This method for producing an ethylene-vinyl alcohol copolymer hydrous composition is characterized by comprising the following process: a vessel is fed with an ethylene-vinyl alcohol copolymer solution containing 100 pts.wt. of an ethylene-vinyl alcohol copolymer and >=50 pts.wt. of an alcohol with a boiling point of <=100 deg.C, the solution is then contacted with steam in the vessel to discharge the alcohol together with the steam out of the vessel, and the resultant ethylene-vinyl alcohol copolymer hydrous composition comprising 100 pts.wt. of the ethylene-vinyl alcohol copolymer, 0-10 pt(s).wt. of the alcohol and 10-500 pts.wt. of water is discharged from the vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a water-containing composition of an ethylene-vinyl alcohol copolymer, and to an ethylene-vinyl alcohol copolymer pellet obtained by the method.

[0002]

2. Description of the Related Art Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) has an oxygen barrier property,
It is a useful polymer material having excellent fragrance retention, oil resistance, non-charging properties, mechanical strength, and the like, and is widely used by being formed into films, sheets, containers, and the like. As a method for producing EVOH, there is a method of saponifying an ethylene-vinyl ester copolymer obtained by polymerizing ethylene and a fatty acid vinyl ester such as vinyl acetate in an organic solvent containing alcohol in the presence of a saponification catalyst. General.

As a method for post-treatment of an alcohol solution of EVOH obtained by saponification, Japanese Patent Publication No. 47-38634 (US Pat. No. 3,847,845) discloses a method in which a methanol solution of EVOH is concentrated if necessary, and then EVOH is precipitated. An amount of water is added to the extent not to produce an EVOH methanol-water mixed solution containing 15 to 45% by weight of EVOH, and this is mixed with water at 50 ° C. or lower or a methanol-water mixed solution having a lower methanol concentration than the above solution. A method for producing EVOH pellets, which is extruded into a solution, precipitated into a strand, and then cut, is described. It is said that the methanol-water mixed solution in the coagulation bath at this time preferably contains 10 to 50% by weight of methanol. It is described that the pellets thus obtained are porous, the saponification catalyst residue can be easily washed off with water, and the handling is easy even in the subsequent washing and drying step.

A method for adding water to a methanol solution of EVOH after saponification is described in, for example, JP-A-11-9092.
No. 7 (EP 937557), a methanol solution having a water content of 62.5% by weight was added to a methanol solution of EVOH having a resin content of 30% by weight,
It is supplied under azeotropic conditions of 0 ° C. and a pressure of 3 kg / cm ² G,
A method is described in which methanol is distilled off until the resin concentration reaches 40% by weight to obtain a completely transparent methanol / water homogeneous solution.

[0005]

However, when EVOH pellets are produced by a method in which an EVOH solution containing a large amount of methanol is precipitated in a coagulation bath as described above, alcohol may be volatilized during the precipitation operation.
The volatilization of alcohol not only deteriorates the working environment and impairs the health of workers, but also adversely affects the surrounding environment.

[0006] Among the EVOHs, those having an ethylene content of less than 20 mol% and / or a saponification degree of 95% are used.
%, The strand is hard to precipitate due to a low coagulation speed in the coagulation liquid, so that cut mistakes and fine powder are liable to occur and stable production can be achieved. It was difficult. In addition, even if EVOH has an ethylene content of 20 mol% or more and a saponification degree of 95% or more, solidification does not occur when strands are deposited at a high speed or by increasing the number of nozzles in order to improve production efficiency. Insufficiency or difficulty in handling resulted in frequent cut mistakes, making it difficult to achieve stable production.

[0007] Furthermore, since the pellets obtained by the conventional method contain alcohol and an alkali metal salt which is a catalyst residue at the time of saponification, a washing step for removing these is required. To increase the cleaning speed, it is effective to increase the temperature of the cleaning solution.However, if the temperature is increased too much, the pellets will fuse together because alcohol is contained in the pellets, and the cleaning speed will be sufficiently increased. There was a problem that can not be.

[0008] That is, an object of the present invention is to provide a method for producing a water-containing EVOH composition that can efficiently remove alcohol without deteriorating the working environment and surrounding environment. In addition, EVO obtained from the water-containing composition thus obtained can be produced stably and has a high washing speed.
We also provide H pellets.

[0009]

Means for Solving the Problems The present inventors have intensively studied and made contact with an ethylene-vinyl alcohol copolymer solution containing alcohol and water vapor to bring out the alcohol together with water vapor. By providing a method for producing a combined aqueous composition,
It has been found that the problem of the invention is solved.

That is, according to the present invention, an ethylene-vinyl alcohol copolymer solution containing 50 parts by weight or more of an alcohol having a boiling point of 100 ° C. or less per 100 parts by weight of an ethylene-vinyl alcohol copolymer is introduced into a container. The alcohol is led out together with water vapor by contact with water vapor in a container, and ethylene-vinyl alcohol copolymer 100
An ethylene-vinyl alcohol copolymer containing 0 to 10 parts by weight of the alcohol and 10 to 500 parts by weight of water with respect to parts by weight of the ethylene-vinyl alcohol copolymer. This is a method for producing a combined water-containing composition.

In the above production method, it is preferable that the ethylene-vinyl alcohol copolymer solution is continuously introduced into the container. It is also preferable to bring the ethylene-vinyl alcohol copolymer solution into contact with steam in a tower-shaped vessel, or to bring them into countercurrent contact. As a specific embodiment, the ethylene-vinyl alcohol copolymer solution is introduced from the top of the tower, steam is introduced from the bottom of the tower, and the ethylene-vinyl alcohol copolymer water-containing composition is derived from the bottom of the tower. It is preferable to use a production method in which the alcohol is discharged from the top of the column together with the steam.

It is preferable that the amount of water vapor introduced is 0.3 to 30 times the weight of the ethylene-vinyl alcohol copolymer solution in terms of weight ratio. Further, when the ethylene-vinyl alcohol copolymer solution is brought into contact with steam, the temperature in the container is 100 to 15
A manufacturing method at 0 ° C. and a pressure of 1 to 6 kg / cm ² is also suitable.

The alcohol used in the present production method is preferably methanol. It is also preferred that the ethylene-vinyl alcohol copolymer has an ethylene content of 3 to 70 mol% and a saponification degree of 80 mol% or more.

Another aspect of the present invention is an ethylene-vinyl alcohol copolymer pellet obtained by cutting the water-containing composition of an ethylene-vinyl alcohol copolymer obtained by the above-mentioned production method. At this time, ethylene-vinyl alcohol copolymer pellets obtained by extruding the aqueous composition of the ethylene-vinyl alcohol copolymer in a molten state into a coagulating liquid in the form of a strand, coagulating, and then cutting are preferable. Also, ethylene-vinyl alcohol copolymer pellets obtained by cutting the above-mentioned water-containing composition of ethylene-vinyl alcohol copolymer in a molten state are suitable.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The EVOH used in the present invention is:
Usually, it is obtained by saponifying an ethylene-vinyl ester copolymer. The ethylene content is usually from 3 to 70 mol%, and from the viewpoint of obtaining a molded article having excellent gas barrier properties and melt moldability, preferably from 10 to 60 mol%, more preferably from 20 to 55 mol%, Most preferably, it is 25 to 55 mol%. Further, the degree of saponification of the vinyl ester component is usually at least 80 mol%, and from the viewpoint of obtaining a molded article having excellent gas barrier properties, it is preferably at least 95 mol%, particularly preferably at least 99 mol%.

On the other hand, EV having an ethylene content of 3 to 20 mol%
OH is suitably used as EVOH to which water solubility has been imparted, and such an EVOH aqueous solution has excellent barrier properties and coating film moldability, and is used as an excellent coating material.

In addition, EVO having a saponification degree of 80 to 95 mol%
H may be used to improve moldability. Such EVOH can be used alone, but an embodiment in which EVOH is used by blending with EVOH having a degree of saponification of more than 99 mol% is also suitable.

However, from the viewpoint of the production process, any of the EVOH having an ethylene content of 3 to 20 mol% and the EVOH having a saponification degree of 80 to 95 mol% can be obtained by adding a methanol solution of the EVOH to a coagulation bath. It was difficult to extrude and precipitate in a strand shape. EV like this
OH can be easily coagulated,
The present invention is also significant from the viewpoint of stable production of pellets.

If the ethylene content of EVOH is less than 3 mol%, melt moldability is generally poor, and water resistance, hot water resistance, and gas barrier properties under high humidity may be reduced. On the other hand, 70
If it exceeds mol%, the barrier properties, printability and the like are often insufficient. If the saponification degree is less than 80 mol%,
In many cases, the barrier properties, coloring resistance, and moisture resistance are unsatisfactory.

Hereinafter, a method for producing EVOH will be specifically described. The polymerization of ethylene and vinyl ester is not limited to solution polymerization, but may be any of solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization. Further, either a continuous type or a batch type may be used. One example of polymerization conditions for batch-type solution polymerization is shown below.

Solvent: An alcohol having a boiling point of 100 ° C. or less is used. Alcohol is employed in view of the solubility of the ethylene-vinyl ester copolymer or EVOH and the handleability. The reason why the boiling point is required to be 100 ° C. or less is that when replacing alcohol with water, alcohol having a lower boiling point than water is more efficiently replaced. The boiling point is preferably at most 80 ° C, more preferably at most 70 ° C. Examples of the alcohol having a boiling point of 100 ° C. or less include methyl alcohol, ethyl alcohol, and n.
-Propyl alcohol, isopropyl alcohol, t-
Although butyl alcohol and the like are exemplified, methyl alcohol is particularly preferable.

Catalyst: 2,2-azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), 2,2-azobis- (4-methoxy-2,4-
Dimethylvaleronitrile), 2,2-azobis- (2-
Azonitrile initiators such as cyclopropylpropionitrile) and isobutyryl peroxide, cumyl peroxy neodecanoate, diisopropyl peroxy carbonate, di-n-propyl peroxy dicarbonate, t-butyl peroxy neodecanoate And organic peroxide-based initiators such as lauroyl peroxide, benzoyl peroxide and t-butyl hydroperoxide.

Vinyl esters; vinyl acetate, fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) and the like can be used, but vinyl acetate is preferred. EVOH can contain 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component.
Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyl tri (β-methoxy-ethoxy) silane and γ-methacryloxypropylmethoxysilane.
Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

The polymerization conditions are as follows. (1) Temperature: 20 to 90 ° C, preferably 40 to 70 ° C
° C. (2) hours; 2 to 15 hours, preferably 3 to 11 hours. (3) Polymerization rate: 10 to 9 based on charged vinyl ester
0%, preferably 30-80%. (4) Resin content in the solution after polymerization; 5 to 85%, preferably 20 to 70%. (5) Ethylene content in the copolymer: 3 to 70 mol%.
Preferably 10 to 60 mol%, more preferably 20 to 55 mol%.
Mol%, optimally 25-55 mol%.

In addition to the ethylene and vinyl esters, monomers copolymerizable therewith, such as propylene, isobutylene, α-octene, α-dodecene, etc .; acrylic acid, methacrylic acid, crotonic acid, maleic acid Acids, unsaturated acids such as itaconic acid or anhydrides, salts or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; ethylene sulfonic acid, allyl sulfonic acid; An olefin sulfonic acid such as methallyl sulfonic 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.

After the polymerization for a predetermined time reaches a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and 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 solution 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 tower filled with Raschig rings,
A vapor of an organic solvent, preferably an alcohol having a boiling point of 100 ° C. or less, and most preferably methanol is blown from the bottom of the column, a mixed vapor of the organic solvent and unreacted vinyl ester is distilled off from the top of the column, and unreacted vinyl is vaporized from the bottom of the column. A method of taking out the copolymer solution from which the ester has been removed is employed.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl esters have been removed to saponify the vinyl ester components in the copolymer. The saponification method is continuous,
Both batch types are possible. 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. (1) Concentration of the copolymer solution; 10 to 50% (2) Reaction temperature; 30 to 65 ° C. (3) Amount of catalyst used; 0.02 to 1.0 equivalent (per vinyl ester component) (4) Time; 1-6 hours

After the reaction, the EVOH solution is usually EVOH 10
5 parts by weight of alcohol having a boiling point of 100 ° C. or less
0 parts by weight or more. The content of the alcohol is preferably at least 70 parts by weight, more preferably at least 80 parts by weight. The content of the alcohol is preferably 10
It is not more than 00 parts by weight, more preferably not more than 500 parts by weight. By setting such alcohol content,
The fluidity of the EVOH solution is ensured, and efficient resin production is possible. The alcohol is preferably methanol. The saponified EVOH solution may be not only an alcohol solution but also a solution of a mixed solvent to which another solvent such as water is added as necessary. Examples of the method for adding water include the method described in the above-mentioned prior art.

The present invention relates to an ethylene-vinyl alcohol copolymer containing 50 parts by weight or more of an alcohol having a boiling point of 100 ° C. or less based on 100 parts by weight of the ethylene-vinyl alcohol copolymer obtained as described above. The coalescing solution is introduced into a container, and brought into contact with water vapor in the container to derive the alcohol together with water vapor.The alcohol is 0 to 10 parts by weight and water is 10 to 10 parts by weight of the ethylene-vinyl alcohol copolymer. A method for producing a water-containing ethylene-vinyl alcohol copolymer composition, comprising deriving a water-containing composition of an ethylene-vinyl alcohol copolymer containing up to 500 parts by weight from the container.

That is, as described above, E after saponification
The VOH solution is usually obtained as a solution containing a large amount of alcohol.In the present invention, such an EVOH solution is introduced into a container and brought into contact with water vapor in the container, so that the alcohol is discharged from the container together with the water vapor, An EVOH-containing composition having a low alcohol content is derived from a container.

The method for bringing the EVOH solution introduced into the container into contact with water vapor in the container is not particularly limited, and may be a continuous method or a batch method. Also, the form of the container is not particularly limited, but a tower type container is preferable in the case of a continuous type, and a tank type container is preferable in the case of a batch type. In view of production efficiency, a continuous type is preferable industrially. Examples of the tower type container include a tray column such as a perforated plate tower and a bubble bell tower, and a packed tower containing a ring-type packing.

It is preferable that the EVOH solution and the steam introduced into the container are brought into contact with each other in countercurrent from the viewpoint of alcohol removal efficiency. For example, in a tower-type vessel, an EVOH solution is introduced from the top of the tower, steam is introduced from the bottom of the tower and brought into countercurrent contact with the solution, the EVOH-containing composition is led out from the bottom of the tower, and alcohol is introduced from the top of the tower together with the steam. A method of derivation can be cited as a preferred embodiment. Alcohol vapor and water vapor derived from the upper part of the column are condensed in a condenser, taken out as an aqueous alcohol solution, purified if necessary, and reused.

If the introduction amount of water vapor is too small, the efficiency of removing alcohol is poor, and if it is too large, it is disadvantageous in terms of cost. It is preferably 30 times (weight ratio),
More preferably 0.5 to 10 times, even more preferably 0.7 to
5 times. The steam to be brought into contact with the EVOH solution may contain 10 parts by weight or less of alcohol with respect to 100 parts by weight of steam, but it is preferable that the steam does not contain alcohol in order to efficiently remove the alcohol. .

The temperature in the processing vessel is preferably 100 to 150 ° C. When the temperature in the container is lower than 100 ° C., the fluidity of the EVOH-containing composition becomes insufficient, and there is a possibility that the EVOH-containing composition may be gelled or clogged in the processing container. The temperature is more preferably 110 ° C or higher, and still more preferably 120 ° C or higher. On the other hand, when the temperature in the container exceeds 150 ° C., the EVOH resin may deteriorate.
More preferably, it is 140 ° C. or lower. Also, if the pressure in the processing vessel is too low, the efficiency of removing alcohol is poor,
On the other hand, if the temperature is too high, the temperature of the EVOH solution in the processing vessel rises and thermal degradation of the EVOH is likely to occur.
６6 kg / cm ² , preferably 1.5-5 kg / cm
² , more preferably ^{2 to 4} kg / cm ² .

In the present invention, the EVOH solution comes into direct contact with water vapor in the container, and the alcohol content gradually decreases, during which the EVOH is in the form of a swollen paste,
It is possible to take out from the container without gelation while maintaining the fluidity. EVOH can be used under normal pressure, for example, 60
It is soluble in a water / methanol mixed solvent at a temperature of about 70 ° C., but cannot be dissolved under normal pressure if the solvent is water alone. However, it has been found that, in the presence of pressurized steam at a temperature of 100 ° C. or higher, for example, EVOH can maintain fluidity even in a state containing substantially only water. As a result, continuous treatment using, for example, a tower-shaped container or the like has become easy.

The aqueous EVOH composition drawn out of the container contains the above alcohol in an amount of 100 parts by weight of EVOH.
It contains 10 to 10 parts by weight and 10 to 500 parts by weight of water and is discharged from the vessel in a fluidized state. The content of the alcohol in the EVOH-containing composition is 0 to 10 parts by weight, preferably 0 to 5 parts by weight, more preferably 0 to 1 part by weight, and still more preferably 0 to 0.1 part by weight. It is. Since the alcohol content is low, volatilization of alcohol in a post-process such as precipitation can be prevented, and work environment or surrounding environment can be preserved. Also, when washing the saponification catalyst residue, etc., even if the temperature of the washing water is increased, the pellets are unlikely to stick to each other, so that the washing water temperature can be increased,
As a result, the washing speed can be increased.

The content of water in the EVOH-containing composition is from 10 to 500 parts by weight. If the water content is less than 10 parts by weight, the fluidity in the processing container will be insufficient. It is preferably at least 30 parts by weight, more preferably at least 50 parts by weight. On the other hand, if the water content exceeds 500 parts by weight,
When it is deposited in the form of a strand, it is difficult to perform stable precipitation, and when it is cut in a molten state, there arises a problem that the cut pellets are mutually fused or the shape becomes non-uniform. It is preferably at most 300 parts by weight, more preferably at most 200 parts by weight. The water-containing EVOH composition thus obtained usually contains 0.1 to 5 parts by weight of a metal equivalent with respect to 100 parts by weight of EVOH, as well as by-product salts and other impurities, in addition to alkali metal salts.

Pellets can be produced by cutting the EVOH-containing composition derived from the container.
The cutting method is not particularly limited. EVOH in molten state
Examples include a method of extruding a water-containing composition into a coagulating liquid into a strand and coagulating the composition, followed by cutting, or a method of cutting directly in a molten state.

When extruding into a strand and coagulating before cutting, the EVOH-containing composition derived from the container is extruded from a nozzle into a coagulating liquid to form a strand having a desired diameter. At this time, if the water content of the EVOH-containing composition is too high, moisture is separated from the EVOH-containing composition, and such separated water is discharged from the nozzle, which may make it difficult to obtain a continuous strand. Therefore, it is preferable that the moisture in the EVOH is previously reduced by a kneader or the like, and then extruded from a nozzle and solidified into a strand. Here, the kneader means a cylinder that is provided with a liquid outlet and a screw that is attached to the cylinder.

Although water is used for the coagulating liquid, a small amount of alcohol may be contained. In the conventional method in which a methanol solution of EVOH or a mixed solution of water / methanol is extruded into a coagulation liquid, methanol is added to the coagulation liquid to reduce the specific gravity of the coagulation liquid, and the coagulation bath is discharged before the discharged strand is deposited. In the present invention, it is necessary to prevent the surface from rising, but in the present invention, water containing no alcohol can be used in the coagulation bath because of the high coagulation speed, and it is excellent in terms of improving the working environment and discharging to the surrounding environment. .

The temperature of the coagulating liquid is preferably from 0 to 50 ° C., and the temperature of the EVOH-containing composition in a molten state during extrusion is preferably from 100 to 150 ° C. By this temperature difference, the EVOH-containing composition can be solidified. The liquid temperature of the coagulation liquid is preferably 0 to 30C. Further, the temperature of the EVOH-containing composition in a molten state is preferably 110 to 140 ° C.

The solidified strand is cut into pellets by a cutter. A strand cutter is suitably used as the cutter.

When the EVOH-containing composition is directly cut in a molten state, a hot-cut method or an underwater-cut method is preferably used as a method for cutting the EVOH-containing composition derived from the container. . From the viewpoint of easy handling of the pellets, the diameter of the nozzle is preferably 2 to 5 mmφ (φ is the diameter; the same applies hereinafter). FIG. 2 shows an example of a hot cutter used in the hot cutting method. 13 is a supply port of the EVOH aqueous composition, 14 is a die, 15 is a rotary blade, 16 is a rotating shaft, 17 is a cutter box, 18 is a cooling water supply port, 19 is cooling water, 20 is a water film,
21 is a pellet discharge port, 22 is cooling water and pellets.

If the water content of the EVOH-containing composition is high,
Water may be separated from the VOH-containing composition, and such separated water is discharged from the nozzle, so that stable cutting may be difficult. Therefore, as in the case of cutting the strand, it is preferable that the water in the EVOH water-containing composition is previously reduced by a kneader or the like, and then discharged from the nozzle and cut.

The pellets thus obtained usually contain an alkali metal salt which is a residue of a catalyst used in the saponification. If the pellets are contained in a large amount, quality problems such as coloring will occur. preferable. The washing method is not particularly limited, and examples thereof include a method of washing by immersion in water or an aqueous solution of an acid such as acetic acid.

The washing temperature can be adopted in the range of 0 to 95 ° C. From the viewpoint of improving the cleaning efficiency, the higher the cleaning temperature, the better. However, if the temperature is too high, it is not preferable because the fusion of the pellets occurs. The lower limit of the washing temperature is preferably 20 ° C or higher, more preferably 30 ° C or higher, and most preferably 40 ° C or higher.
° C or higher. The conventional cleaning temperature is generally about 25 to 30 ° C., and one of the features of the present invention is that the cleaning temperature can be higher than that. The upper limit of the washing temperature is preferably 80 ° C or lower, more preferably 70 ° C or lower. The alkali metal salt content after washing is EVOH
0.05 parts by weight or less in terms of metal per 100 parts by weight,
More preferably, the content is 0.03 parts by weight or less.

To the pellets, at least one selected from the group consisting of carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is added in order to improve the quality such as thermal stability. Is preferred. The addition method is not particularly limited, and a known method can be employed. For example, there is a method in which pellets are immersed in an aqueous solution containing at least one selected from the group consisting of a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt, and these are adsorbed.

Examples of the carboxylic acid include oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, lactic acid, and propionic acid. From the viewpoints of cost, availability and the like, acetic acid, lactic acid or propionic acid are used. Preferably, an acid is used. If the content of the carboxylic acid in the dried resin composition pellets composed of EVOH of the present invention is too small, coloring may occur during melt molding, and if it is too large,
Since the interlayer adhesion may be insufficient, 10 to 50
It is preferably carried out at 00 ppm. The lower limit of the carboxylic acid content is preferably at least 30 ppm, more preferably at least 50 ppm. The upper limit of the carboxylic acid content is preferably 1000 ppm or less, and more preferably 500 ppm or less.

Examples of the phosphoric acid compound include various acids such as phosphoric acid and phosphorous acid, and salts thereof. The phosphate may be contained in any form of a first phosphate, a second phosphate, and a third phosphate, and the cationic species thereof is not particularly limited. And alkaline earth metal salts. Among them, it is preferable to add a phosphate compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate. The content of the phosphoric acid compound in the dried resin composition pellets comprising the EVOH of the present invention is preferably from 1 to 1000 ppm in terms of a phosphate group, and by adding the phosphoric acid compound in an appropriate range, the coloring of the molded product is improved. Further, it is possible to suppress the generation of gel and butter. If the content of the phosphoric acid compound is less than 1 ppm, coloring during melt molding may become intense. Also, 1000
If the content exceeds ppm, there is a possibility that gels and buttocks of the molded product are easily generated.

Examples of the boron compound include, but are not limited to, boric acids, borate esters, borates, and borohydrides. Specifically, examples of boric acids include orthoboric acid, metaboric acid, tetraboric acid, and the like.Examples of borate esters include triethyl borate, trimethyl borate, and the like. Alkali metal salts, alkaline earth metal salts of acids,
Borax and the like. Of these compounds, orthoboric acid (hereinafter simply referred to as boric acid) is preferred. E of the present invention
When the content of the boron compound in the pellets of the dried resin composition composed of VOH is too small, the effect of improving the thermal stability is small, and when it is too large, gelation is likely to occur, resulting in poor moldability. 10 to 200 in terms of boron
0 ppm, preferably 50-1000 pp
More preferably, it is carried out at m.

By including an alkali metal salt,
It is possible to effectively improve the interlayer adhesion and compatibility. The addition amount of the alkali metal salt in the dried resin composition pellets made of EVOH of the present invention is preferably from 5 to 5000 ppm in terms of an alkali metal element. More preferably 20
To 1000 ppm, more preferably 30 to 750 p
pm. Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal salt include an aliphatic carboxylate, an aromatic carboxylate, a phosphate, and a metal complex. For example, sodium acetate, potassium acetate, sodium propionate, sodium phosphate, lithium phosphate, sodium stearate,
Examples thereof include potassium stearate and a sodium salt of ethylenediaminetetraacetic acid. Among them, sodium acetate, potassium acetate, sodium propionate, and sodium phosphate are preferred.

It is also preferable to add an alkaline earth metal salt. When the alkaline earth metal salt is added, the coloring resistance may be slightly deteriorated, but the amount of the resin which has been thermally degraded during melt molding and adhered to the die of the molding machine can be reduced. The alkaline earth metal salt is not particularly limited, and examples thereof include a magnesium salt, a calcium salt, a barium salt, and a beryllium salt. Particularly, a magnesium salt and a calcium salt are preferable. The anionic species of the alkaline earth metal salt is not particularly limited, but an aliphatic carboxylate anion or a phosphate anion is preferable. Among them, magnesium acetate, calcium acetate, magnesium propionate, calcium propionate, magnesium phosphate and calcium phosphate are preferred. The content of the alkaline earth metal in the pellets of the dried resin composition comprising the EVOH of the present invention is preferably from 10 to 1,000 ppm, more preferably from 20 to 500 ppm, in terms of metal. If the content of the alkaline earth metal salt is less than 10 ppm, the effect of improving the long-run property may be insufficient, and if it exceeds 1000 ppm, the coloring at the time of melting the resin may be intense.

The obtained pellet is usually subjected to a drying step. The moisture content of the resin composition pellets made of EVOH after drying is generally 1% by weight or less, preferably 0.1% by weight.
Not more than 5% by weight. EVO with conventional alcohol
The H solution is coagulated in a coagulating liquid into a strand, and then the pellet is obtained by extruding the water-containing composition of the present invention into a strand and cutting it, as compared with the pellet obtained by cutting the strand. Is one of the features that the drying speed is fast. Therefore, in this case, it is possible to shorten the drying time as compared with the related art, which is advantageous in terms of cost. Such a drying method is not particularly limited, but a stationary drying method, a fluidized drying method and the like are preferred. It is also possible to employ a multi-stage drying step in which several drying methods are combined, such as a method of first drying by a fluidized drying method, followed by a method of drying by a static drying method. . When drying the water-containing composition of the present invention, even if the conventional drying method could not be efficiently dried without combining a plurality of drying methods, there is a case that can be efficiently dried by only one drying method, drying time One of the useful points is not only the shortening of the drying process but also the high degree of freedom in adopting the drying process.

[0054]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. FIG. 1 is a schematic diagram of an EVOH pellet manufacturing apparatus used in Example 1. An EVOH solution as a raw material is introduced into the tower from the uppermost stage 2 of the tray column 1, and steam is introduced into the tower from the lowermost stage 3 of the tray column. The EVOH solution moves downward from above in the column, and the steam moves upward from below in the column, and the two come into countercurrent contact. A mixed vapor of water and methanol is led out from the tower top 4, condensed in the condenser 23, and collected as an aqueous methanol solution. EVO from tower bottom 5
The H-containing composition is led out and introduced into the kneader 6. Water containing a small amount of methanol is discharged from the discharge port 7 in the kneader 6, and the EVOH-containing composition strand 9 is discharged from the discharge port 8.
Is discharged. The EVOH hydrous composition strand 9 is coagulated in a coagulation liquid 11 filled in a coagulation tank 10 and then cut into pellets by a strand cutter 12.

Example 1 EVOH containing 100 parts by weight of methanol, 50 parts by weight of water and 2 parts by weight of sodium acetate in terms of sodium based on 100 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5 mol%. The solution is continuously supplied at a rate of 52 kg / hr from the uppermost stage of a tray column having a diameter of 0.3 m and a number of stages of 10, and steam is blown at a rate of 86 kg / hr from the lowermost stage to contact the EVOH solution and the steam in countercurrent. I let it. The temperature in the tower was 130 ° C., and the pressure in the tower was 3 kg / cm ² . The methanol vapor and water vapor distilled off from the top were condensed in a condenser and recovered as a methanol aqueous solution. The EVOH-containing composition was extracted from the bottom of the tower. This EVOH
The water-containing composition contained 0.05 parts by weight of methanol, 105 parts by weight of water, and 2 parts by weight of sodium acetate in terms of sodium based on 100 parts by weight of EVOH.

Next, this EVOH aqueous composition was treated with a liquid outlet having a diameter of 50 mm and a length of 660 mm (L / D =
13.2) was supplied to the kneader at 41 kg / hr. The rotation speed of the screw at this time was 100 rpm. The EVOH-containing composition obtained from the discharge port contains 0.03 parts by weight of methanol, 63 parts by weight of water, and 1.2 parts by weight of sodium acetate in terms of sodium with respect to 100 parts by weight of EVOH. ° C. Subsequently, this EVOH-containing composition was extruded into a coagulation liquid composed of water at 10 ° C. from four nozzles (diameter 6 mm) to coagulate in a strand shape. After taking out from the coagulation liquid, it was cut into pellets with a strand cutter.

The obtained pellets were washed with water at 50 ° C. until the content of sodium acetate became 0.002% by weight in terms of sodium. The pellets did not fuse together during the washing. The washed pellets were immersed in an aqueous solution of acetic acid 0.09% and sodium dihydrogen phosphate 0.022% for 2 hours and drained. Thereafter, it took 3 hours at 100 ° C. to dry to a moisture content of 0.2% by weight. The pellet after drying is
Acetic acid contained 510 ppm, sodium element 52 ppm, and phosphate group 107 ppm. This pellet could be used for various moldings. During these operations, methanol did not evaporate into the atmosphere, and the working environment was good.

Example 2 Steam was blown at 42 kg / hr from the bottom of a tray column, the temperature in the column was 124 ° C., and the pressure in the column was 2.5 kg / hr.
except that the cm ² is was operated similarly to the water-containing composition manufacturing process described in Example 1, from the bottom, EVOH100
An EVOH-containing composition containing 0.8 parts by weight of methanol and 102 parts by weight of water with respect to parts by weight was obtained. During this operation, methanol did not evaporate into the atmosphere, and the working environment was good.

Example 3 A water-containing solution as described in Example 1 except that an EVOH solution containing 185 parts by weight of methanol was used as a raw material with respect to 100 parts by weight of EVOH having an ethylene content of 55 mol% and a saponification degree of 90.5 mol%. By operating in the same manner as in the composition production step, an EVOH-containing composition containing 0.08 parts by weight of methanol and 87 parts by weight of water with respect to 100 parts by weight of EVOH was obtained from the bottom of the tower. During this operation, methanol did not evaporate into the atmosphere, and the working environment was good.

Example 4 300 kg of an EVOH solution containing 140 parts by weight of methanol and 90 parts by weight of water with respect to 100 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5 mol% were placed in a 500-L tank vessel. Water was continuously blown from the lower part of the container at a rate of 75 kg / hr. The temperature in the container was 138 ° C., and the pressure was 4 kg / cm ² . Methanol vapor and water vapor were distilled off from the upper part of the vessel, and these were condensed in a condenser and recovered as an aqueous methanol solution. After 10 hours from the start of the steam injection, the injection was stopped and the EVOH-containing composition was taken out from the bottom of the tower. This aqueous EVOH composition contained 7 parts by weight of methanol and 125 parts by weight of water based on 100 parts by weight of EVOH. During this operation, methanol did not evaporate into the atmosphere, and the working environment was good.

Example 5 In Example 1, 85 parts by weight of methanol, 85 parts by weight of water and sodium acetate were added to 3 parts by weight of 100 parts by weight of EVOH having an ethylene content of 17 mol% and a saponification degree of 99.1 mol%. The same operation as in Example 1 was carried out except that the EVOH solution containing parts by weight was used.
It took 6 hours at 100 ° C. to dry to 2% by weight. The dried pellets contained 550 ppm of acetic acid, 61 ppm of sodium element, and 114 ppm of phosphate groups. This pellet could be used for various moldings.

Example 6 The same operation as in Example 1 was carried out except that ethanol was used instead of methanol.
0.4 parts by weight of ethanol and 100 parts by weight of water
An aqueous EVOH composition containing 07 parts by weight and 2 parts by weight of sodium acetate in terms of sodium was obtained. Subsequently, as in Example 1, the mixture was passed through a kneader, solidified in a strand shape, cut, washed with water, immersed in an aqueous solution of acetic acid and sodium dihydrogen phosphate, and drained. It took 3 hours at 100 ° C. to dry to a moisture content of 0.2% by weight. After drying, the pellets contained 480 ppm of acetic acid and 47 p of sodium.
pm, 95 ppm of phosphate groups. This pellet could be used for various moldings.

Example 7 EVOH containing 100 parts by weight of methanol, 50 parts by weight of water and 2 parts by weight of sodium acetate in terms of sodium with respect to 100 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 90.5 mol%. The solution is continuously supplied at a rate of 52 kg / hr from the uppermost stage of a tray column having a column diameter of 0.3 m and a number of stages of 10, and steam is blown at a rate of 86 kg / hr from the lowermost stage to contact the EVOH solution and the steam in countercurrent. I let it. The temperature in the tower was 130 ° C., and the pressure in the tower was 3 kg / cm ² .
Methanol vapor and water vapor were distilled off from the top of the column, and these were condensed in a condenser and recovered as an aqueous methanol solution. The EVOH-containing composition was extracted from the bottom of the tower. This EVO
The H-containing composition contained 0.05 parts by weight of methanol, 105 parts by weight of water, and 2 parts by weight of sodium acetate in terms of sodium based on 100 parts by weight of EVOH.

Next, this EVOH-containing composition was treated with a liquid outlet having a diameter of 50 mm and a length of 660 mm (L / D =
13.2) was supplied to the kneader at 41 kg / hr. The rotation speed of the screw at this time was 100 rpm. The EVOH-containing composition obtained from the discharge port contains 0.03 parts by weight of methanol, 63 parts by weight of water, and 1.2 parts by weight of sodium acetate in terms of sodium with respect to 100 parts by weight of EVOH. ° C. Subsequently, the EVOH aqueous composition was extruded from a die having a hole diameter of 3 mm and six holes, and cut at a distance of 0.05 mm from the die by a hot cutter having four blades. The rotation speed of the cutter blade was 1200 rpm.

The obtained pellets were washed with water at 50 ° C. until the content of sodium acetate became 0.002% by weight in terms of sodium. The pellets did not fuse together during the washing. The washed pellet was immersed in an aqueous solution of 0.09% of acetic acid and 0.022% of sodium dihydrogen phosphate at 50 ° C. for 4 hours to be drained. Then, it was dried with a hot air drier to a moisture content of 0.2% by weight. After drying, the pellets contain 40% acetic acid.
0 ppm, sodium element 35 ppm, phosphate group 8
It contained 8 ppm. This pellet could be used for various moldings.

Example 8 In Example 7, 85 parts by weight of methanol, 85 parts by weight of water and sodium acetate were converted into 3 parts by weight of 100 parts by weight of EVOH having an ethylene content of 17 mol% and a saponification degree of 99.1 mol%. The same operation as in Example 7 was carried out except that the EVOH solution containing parts by weight was supplied to the tray column. Even during washing with water at 50 ° C., there was no fusion between the pellets. After drying, the pellets contained 450 ppm of acetic acid and 40 ppm of sodium.
ppm and phosphoric acid radicals were 94 ppm. This pellet could be used for various moldings.

Example 9 Example 7 except that ethanol was used instead of methanol.
When the same operation as described above was carried out, EVOH1
0.4 parts by weight of ethanol and 107 parts by weight of water
An aqueous EVOH composition containing 2 parts by weight of sodium acetate and 2 parts by weight of sodium acetate was obtained. Subsequently, after passing through a kneader, the sheet was cut with a hot cutter in the same manner as in Example 7.
After washing with water, the substrate was immersed in an aqueous solution of acetic acid and sodium dihydrogen phosphate to drain the solution. Even during washing with water at 50 ° C., there was no fusion between the pellets. After drying, the pellets were acetic acid 410pp
m, 44 ppm of sodium element and 90 p of phosphate group
pm. This pellet could be used for various moldings.

Comparative Example 1 EVOH 100 which is an EVOH having the same composition as in Example 1 and has an ethylene content of 32 mol% and a saponification degree of 99.5 mol%
An EVOH solution containing 100 parts by weight of methanol, 50 parts by weight of water and 2 parts by weight of sodium acetate in terms of sodium based on 10 parts by weight of methanol, 10 parts by weight of methanol and 90 parts by weight of water
4 nozzles (diameter 6 m) in a coagulation liquid at 10 ° C.
m) and solidified into a strand. After taking out from the coagulation liquid, it was cut into pellets with a strand cutter. When the obtained pellets were washed with water at 50 ° C. until the sodium acetate content became 0.002% by weight in terms of sodium, the pellets were strongly fused during the washing with water. The washed pellet was immersed in an aqueous solution of 0.09% of acetic acid and 0.022% of sodium dihydrogen phosphate for 2 hours and drained.
Thereafter, the drying time for obtaining the same water content of Example 1 as 0.2% by weight was 35 hours at 100 ° C. The dried pellets contained 510 ppm of acetic acid, 53 ppm of sodium, and 104 ppm of phosphate.

Comparative Example 2 EVOH having the same composition as that of Example 5 and having an ethylene content of 17 mol% and a saponification degree of 99.1 mol%.
85 parts by weight of methanol, 85 parts by weight of water and 3 parts by weight of sodium acetate in terms of sodium
A VOH solution was placed in a coagulation liquid at 10 ° C. consisting of 5% by weight of methanol and 95% by weight of water, with four nozzles (diameter 6 mm).
However, the coagulability was poor, and the strand was broken immediately, so that the operation could not be further continued.

Comparative Example 3 EVOH containing 100 parts by weight of methanol, 50 parts by weight of water and 2 parts by weight of sodium acetate in terms of sodium based on 100 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 90.5 mol%. The solution was extruded from 6 nozzles (3 mm in diameter) into a coagulating liquid at 10 ° C. consisting of 10% by weight of methanol and 90% by weight of water, and was coagulated into strands. At this time, many strand breaks occurred and the operation was unstable. After taking out from the coagulation liquid, it was cut into pellets with a strand cutter. 50 pellets obtained
When washed with water at ℃, the fusion between the pellets was severe and pellets usable for various molding purposes could not be obtained.

[0071]

According to the present invention, it is possible to provide a method for producing an EVOH-containing composition capable of efficiently removing alcohol without deteriorating the working environment and the surrounding environment.
Further, it is possible to provide EVOH pellets which can be stably produced from the water-containing composition thus obtained and have a high washing speed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an EVOH pellet manufacturing apparatus used in Example 1.

FIG. 2 is a diagram showing an example of a configuration of a hot cutter used in the present invention.

[Description of Signs] 1 shelf tower 2 top 3 bottom 4 tower top 5 tower bottom 6 kneader 7 discharge port 8 discharge port 9 EVOH-containing composition strand 10 coagulation tank 11 coagulation liquid 12 strand cutter 13 EVOH-containing composition Supply port 14 Die 15 Rotary blade 16 Rotary axis 17 Cutter box 18 Cooling water supply port 19 Cooling water 20 Water film 21 Pellet outlet 22 Cooling water and pellet 23 Condenser

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukihiro Ohara 1-2-1 Kaigandori, Okayama-shi, Okayama F-term in Kuraray Co., Ltd. (Reference) 4F070 AA13 AA26 AC12 AC36 AE28 BA02 CA12 CA16 CB05 CB11 DA21 DA41 DA50

Claims (10)

[Claims] 1. An ethylene-vinyl alcohol copolymer 1.
An ethylene-vinyl alcohol copolymer solution containing 50 parts by weight or more of an alcohol having a boiling point of 100 ° C. or less is introduced into a container, and the alcohol is brought out together with water vapor in the container to bring out the alcohol together with water vapor. With respect to 100 parts by weight of the ethylene-vinyl alcohol copolymer, 0 to 10 parts by weight of the alcohol and 10 to 500 parts by weight of the ethylene-vinyl alcohol copolymer-containing composition containing water are derived from the container. A method for producing an ethylene-vinyl alcohol copolymer hydrate composition, which is characterized by the following. 2. The method for producing a water-containing ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer solution is continuously introduced into the container. 3. The method for producing a water-containing ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer solution and water vapor are brought into contact in a tower type vessel. 4. The method for producing a water-containing ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer solution and steam are brought into countercurrent contact with each other. 5. The ethylene-vinyl alcohol copolymer solution is introduced from the upper part of the tower, steam is introduced from the lower part of the tower, and the ethylene-vinyl alcohol copolymer-containing composition is led out from the lower part of the tower. The method for producing a water-containing composition of an ethylene-vinyl alcohol copolymer according to claim 4, wherein the water-containing composition is derived from the upper part of the tower together with steam. 6. The method according to claim 1, wherein the amount of introduced steam is 0.3 to 30 times the amount introduced of the ethylene-vinyl alcohol copolymer solution by weight. A method for producing a water-containing composition of an ethylene-vinyl alcohol copolymer. 7. The ethylene-vinyl alcohol copolymer
When the temperature in the container at the time of bringing the body solution into contact with water vapor is 1
At a temperature of 00 to 150 ° C and a pressure of 1 to 6 kg / cm ²Who is
The ethylene-vinyl alcohol according to any one of claims 1 to 6,
A method for producing a water-containing polyester copolymer composition. 8. The method for producing a water-containing ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the alcohol is methanol. 9. The ethylene-vinyl alcohol copolymer has an ethylene content of 3 to 70 mol% and a saponification degree of 80.
The method for producing a water-containing ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 8, which is at least mol%. 10. An ethylene-vinyl alcohol copolymer pellet obtained by cutting the ethylene-vinyl alcohol copolymer hydrate composition obtained by the production method according to claim 1.