JP2002284811A - Production method for ethylene-vinyl alcohol copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for an ethylene-vinyl alcohol copolymer whereby an alcohol can be efficiently removed without worsening the work environment and surrounding environment. SOLUTION: This production method has a step (step 1) wherein an ethylene- vinyl alcohol copolymer solution containing at least 50 pts.wt. alcohol having a boiling point of 100 deg.C or lower per 100 pts.wt. ethylene-vinyl alcohol copolymer is introduced into an apparatus to be contacted therein with water to draw out the alcohol together with water, and the resultant water-containing ethylene- vinyl alcohol copolymer composition containing 0-10 pts.wt. alcohol and 10-1,000 pts.wt. water per 100 pts.wt. ethylene-vinyl alcohol copolymer is drawn out of the apparatus; and a step (step 2) wherein the water-containing ethylene-vinyl alcohol copolymer composition is fed to an extruder, melt kneaded, and extruded out of the extruder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene-vinyl alcohol copolymer (hereinafter also referred to as "EVOH").
Method for producing resin and EV obtained by the method
The present invention relates to a method for producing a pellet for cutting an OH resin. More specifically, a step of introducing an EVOH solution containing an alcohol into an apparatus, bringing the EVOH aqueous composition into contact with water in the apparatus, extracting the alcohol with water, and extracting the EVOH aqueous composition from the apparatus, and a step of obtaining the obtained EVOH aqueous composition. The present invention relates to a method for producing an EVOH resin, comprising the steps of: supplying a product to an extruder, melt-kneading the mixture, and discharging the mixture from the extruder, and a method for producing pellets for cutting the EVOH resin obtained by the production method.

[0002]

2. Description of the Related Art EVOH is a useful polymer material having excellent oxygen barrier properties, fragrance retention properties, oil resistance, antistatic properties, mechanical strength, etc., and is widely used in the form of films, sheets, containers and the like. ing. As a method for producing EVOH, an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and a fatty acid vinyl ester such as vinyl acetate is saponified in an organic solvent containing an alcohol in the presence of a saponification catalyst. The method is general.

As a method for post-treatment of an alcohol solution of EVOH obtained by saponification, Japanese Patent Publication No. 47-38634 discloses a method in which a methanol solution of EVOH is concentrated, if necessary, so that EVOH does not precipitate. Is added to produce a methanol / water mixed solution of EVOH containing 15 to 45% by weight of EVOH, which is added to water at 50 ° C. or lower or a methanol / water mixed solution having a lower methanol concentration than the mixed solution. There is disclosed a method for producing EVOH pellets which is extruded, precipitated in a strand shape, and then cut. The methanol / water mixed solution of the coagulation bath preferably contains 10 to 50% by weight of methanol. I have. 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.
In Example 1 of JP-A No. 7 (1999), a methanol solution of EVOH having a resin content of 30% by weight was added with an aqueous methanol solution having a water content of 62.5% by weight at 100 to 110 ° C. under a pressure of 3 kg /
A method is described in which methanol is distilled under an azeotropic condition of cm ² G to distill methanol 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 of precipitating an EVOH solution containing a large amount of methanol 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.

Further, among the EVOHs, when the above method is employed in the production of EVOH having an ethylene content of less than 20 mol% or EVOH having a saponification degree of less than 95%, the coagulation rate in the coagulation liquid is low. Strands are unlikely to precipitate, which causes cut errors and the incorporation of fine powder, making it difficult to produce stably. EVO having an ethylene content of 20 mol% or more and a saponification degree of 95% or more
Even when H is used to increase the production efficiency, if the strands are deposited at high speed or by increasing the number of nozzles, the solidification becomes insufficient or the handling becomes difficult, resulting in cutting. There were many mistakes, and it was difficult to achieve stable production.

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

[0008] On the other hand, there are various methods for molding EVOH pellets into various molded articles, but they are usually melt-molded using an extruder, such as extrusion molding or injection molding. At this time, the molding process is started by charging the raw material EVOH resin pellets into a hopper or the like of an extruder.
However, during molding of EVOH resin, the melting temperature must be 200 ° C or higher. Therefore, EVOH that does not contain additives is liable to deteriorate during melt molding, causing fisheye or lumps in the product and deteriorating the quality. Was sometimes

In order to solve this problem, a method of adding a trace component such as an acidic substance and / or a metal salt to EVOH is known. As one example, a method of improving long-run property and being typified by gel buttocks is known. In order to suppress poor appearance, a metal salt of Group 2 of the periodic table is added in an amount of 0.000 in terms of metal.
5 to 0.05% by weight, pKa of 3.5 or more, boiling point of 180
0.002 to 0.2% by weight of acid above
An acid having a boiling point of not less than 3.5 and a boiling point of not more than 120 ° C. is used in an amount of 0.01 to 0.1.
EVOH containing 2% by weight and exhibiting specific flow characteristics
A composition is disclosed (JP-A-64-66262).

[0010] EV to which the above-mentioned trace components are added
The OH pellets can be obtained by (1) spraying an aqueous solution of a trace component on the EVOH pellets, mixing them with a Henschel mixer, and then drying (JP-A-55-12108). A method in which a trace component is mixed and dry-blended with a supermixer (JP-A-57-34148), and (3) a method in which EVOH pellets are immersed in an aqueous solution containing a trace component, drained, and dried (JP-A- 64-66262), (4)
A method of adjusting the water content of EVOH pellets to 20 to 80% by weight, and then contacting with an aqueous solution of at least one compound selected from the group consisting of a boron compound, an acetate and a phosphate compound (WO99 / 05213). It has been known.

[0011] However, in the addition method of (1) or (2), the uniformity of the trace components in the EVOH pellets is insufficient, and the addition amount is difficult to control, so that a product of stable quality is obtained. It is difficult. On the other hand, the method (3) or (4) has an advantage that the amount of the trace component contained in the EVOH pellet can be easily controlled by adjusting the solution concentration.

Further, EVOH having an ethylene content of less than 20 mol% or EVOH having a saponification degree of less than 95% is difficult to produce pellets stably as described above,
In some cases, it is obtained as a crumb. E having an ethylene content of 20 mol% or more and a saponification degree of 95% or more
Even in the case of VOH, when strands are deposited at a high speed to increase production efficiency or by increasing the number of nozzles, a crumb-like EVOH may still be obtained. However, when the crumb-like EVOH is treated by the method (3) or (4), it is difficult to mix the trace components homogeneously, and it is not possible to obtain a stable quality product.

Further, from the viewpoint of the manufacturing process, in the case of a conventional method of immersing EVOH pellets in a treatment solution containing an acidic substance and / or a metal salt, a treatment bath for immersing the pellets may be used. A processing tower is required. In addition, the processing solution used in such a processing bath or processing tower consumes an acidic substance and / or a metal salt after the EVOH processing. It is necessary to re-add a large amount of acidic substances and / or metal salts. However, it is not preferable to discard the used processing solution as it is from the viewpoint of the impact on the environment, so that a wastewater treatment facility is required. On the other hand, when the processing solution is collected and reused, acidic substances and / or
Alternatively, a facility for re-adding the metal salt and a facility for removing impurities typified by oligomers and the like in the treatment liquid are required.
That is, the conventional method has a problem that a large processing facility and a long processing time are required, and the manufacturing cost is increased.

As a method of melt-extruding EVOH in a water-containing state, a method of melt-extrusion molding with a specific energy (Japanese Patent Application Laid-Open No. 11-58500) and a method of melt-extrusion molding by controlling a specific cylinder temperature (Japanese Patent Application Laid-Open No.
No. 1-58501) has been proposed. However, these documents do not describe adjusting the water content during melt extrusion.

[0015]

That is, an object of the present invention is to provide a method for producing an EVOH resin capable of efficiently removing alcohol without deteriorating the working environment and the surrounding environment. In addition, an EV obtained from the EVOH resin, which can be stably produced and has a high washing speed.
Another object of the present invention is to provide a method for producing OH resin pellets.
The EVOH resin pellets thus obtained have good extrusion stability and heat stability (long run property).

[0016]

Means for Solving the Problems The present inventors have intensively studied and made a contact with an EVOH solution containing an alcohol and brought the alcohol together with water to produce an EVOH-containing composition. It has been found that the object of the present invention can be solved by providing a method for producing an EVOH resin having a step of supplying a product to an extruder and melt-kneading the product.

That is, according to the present invention, an EVOH 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 EVOH is introduced into an apparatus, and brought into contact with water in the apparatus to bring the alcohol together with water. Derived,
The alcohol is added in an amount of 0 to 1 with respect to 100 parts by weight of EVOH.
EVOH containing 0 parts by weight and 10 to 1000 parts by weight of water
Deriving the water-containing composition from the device (step 1); and supplying the EVOH water-containing composition to an extruder, melt-kneading the mixture, and discharging the copolymer from the extruder (step 2). A method for producing an EVOH resin, comprising:

In the above manufacturing method, EVO used
H has an ethylene content of 3 to 70 mol% and a saponification degree of 80.
Preferably, it is at least mol%. Preferably, the alcohol used is methanol.

In the step 1 of the manufacturing method, the EV
An OH solution is introduced into a container, and brought into contact with water vapor in the container to derive the alcohol together with water vapor.
It is preferred that the water-containing composition is discharged from the container.
At that time, the EVOH solution was continuously introduced into the tower type vessel,
It is preferred to contact the water vapor in the container. As a particularly preferred embodiment, the EVOH solution is introduced from the top of the tower, steam is introduced from the bottom of the tower, and the EVOH solution and the steam are brought into countercurrent contact with each other. Then, a method of extracting the alcohol from the upper part of the tower together with the water vapor may be mentioned.

[0020] In the step 2 of the production method, the melting temperature of the resin in the extruder is preferably 70 to 170 ° C. Further, it is preferable that the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight. Further, it is preferable to adjust the water content of the resin in the extruder by supplying insufficient water to the extruder or removing excess water from the extruder. Further, in the step 2, it is preferable that at least one additive selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is blended and melt-kneaded in the extruder. is there. In that case, it is more preferable to mix the additive in an aqueous solution. Also,
It is preferable that a cleaning liquid is injected into the extruder, and the cleaning liquid is discharged from at least one location downstream of the cleaning liquid injection section to remove a saponification catalyst residue.

In a preferred embodiment of the production method of the present invention, the EVO derived from the apparatus in step 1 is
A method in which pellets obtained by cutting the H-containing composition are supplied to the extruder in Step 2 may be used. At that time, it is preferable that the pellets obtained by cutting are immersed in a washing liquid to remove the saponification catalyst residue, and then supplied to the extruder in Step 2. Further, in that case, it is particularly preferable to wash continuously in the tower type vessel. The pellets obtained by cutting are immersed in an aqueous solution containing at least one additive selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts. It is preferred that the additives be added and then fed to the extruder of step 2.

In another preferred embodiment of the production method of the present invention, the EVOH aqueous composition in a molten state derived from the apparatus in step 1 is cut into the extruder in step 2 without cutting. A method of supplying is exemplified. At that time, after the EVOH aqueous composition is supplied to the extruder in Step 2 without cutting, the cleaning liquid is injected into the extruder, and the cleaning liquid is discharged from at least one location downstream of the injection section of the cleaning liquid to remove the washing liquid. It is preferable to remove the catalyst residue.

The present invention also includes a method for producing EVOH resin pellets in which the EVOH resin obtained by any one of the above-mentioned methods is discharged from the extruder in step 2 and then cut. At this time, after cutting, the moisture content is 1% by weight.
It is preferred to dry until:

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a step of introducing an EVOH solution containing an alcohol into an apparatus, bringing the EVOH solution into contact with water in the apparatus, extracting the alcohol together with water, and extracting an aqueous EVOH composition from the apparatus ( The present invention relates to a method for producing an EVOH resin, which comprises a step 1) and a step (step 2) of supplying the obtained EVOH-containing composition to an extruder, melt-kneading the mixture, and discharging the mixture from the extruder. Here, the EVOH resin refers to EVOH obtained by polymerization and saponification, washing, water content adjustment,
An EVOH resin composition finally obtained by performing various treatments such as addition of additives. Step 2 of the present invention
, The EVOH resin composition in the extruder and the EVOH resin composition immediately after the extruder is discharged may also be referred to as an EVOH resin. Therefore, the EVOH resin may contain water, various additives, impurities, and the like.

The EVOH used in the present invention is usually obtained by saponifying an ethylene-vinyl ester copolymer. The ethylene content is usually 3 to 70 mol%, and from the viewpoint of obtaining a molded article having excellent gas barrier properties and melt moldability, preferably 10 to 60 mol%, more preferably 2 to 60 mol%.
0-55 mol%, optimally 25-55 mol%. Further, the saponification degree of the vinyl ester component is usually 80 mol%.
From the viewpoint of obtaining a molded product having excellent gas barrier properties, it is preferably at least 95 mol%, particularly preferably at least 99 mol%.

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

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, EVOH having the above ethylene content of 3 to 20 mol% is used.
In addition, it was difficult for any of the EVOH having a saponification degree of 80 to 95 mol% to extrude a methanol solution of the EVOH into a coagulation bath in the form of a strand to precipitate. The present invention is also significant from the viewpoint that such EVOH can be easily coagulated and pellets can be stably produced.

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,
If it exceeds 70 mol%, barrier properties and printability are often insufficient. When the saponification degree is less than 80 mol%, the barrier properties, coloring resistance and moisture resistance are often unsatisfactory.

Hereinafter, a method for producing EVOH will be specifically described. The copolymerization of ethylene and vinyl ester 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.
An example of polymerization conditions in the batch type solution polymerization is shown below.

Solvent: An alcohol having a boiling point of 100 ° C. or less is used. Ethylene-vinyl ester copolymer and E
Alcohol is employed from the viewpoint of solubility of VOH and handling. 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. Methanol, ethyl alcohol, n-
Examples thereof include propyl alcohol, isopropyl alcohol, and t-butyl alcohol, and 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 , Lauroyl peroxide, benzoyl peroxide, t-
Organic peroxide-based initiators such as butyl hydroperoxide can be used.

Vinyl esters: Fatty acid vinyl esters such as vinyl acetate, vinyl propionate and vinyl pivalate can be used, but vinyl acetate is preferred. Also, E
VOH is a vinylsilane compound 0.00 as a copolymer component.
It can contain from 0.2 to 0.2 mol%. here,
Examples of the vinylsilane-based compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (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%.

Besides ethylene and vinyl esters, monomers copolymerizable therewith, for example, α-olefins such as propylene, isobutylene, α-octene, α-dodecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid Acids, unsaturated acids such as itaconic acid, its anhydrides, salts,
Mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; acrylamide;
Amides such as methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid or salts thereof; alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, and the like in a small amount. It is also possible to polymerize.

After polymerizing for a predetermined time and reaching a predetermined polymerization rate, a polymerization inhibitor is added as necessary, and unreacted ethylene gas is removed by evaporation. As a method to drive out unreacted vinyl ester,
For example, a polymerization solution from which ethylene has been removed is continuously supplied at a constant rate from the upper part of a column filled with Raschig rings, and steam of an organic solvent, preferably an alcohol having a boiling point of 100 ° C. or lower, and most preferably methanol is blown from the lower part of the column. A method of distilling a mixed vapor of the organic solvent and the unreacted vinyl ester from the top of the tower and removing the copolymer solution from which the unreacted vinyl ester has been removed from the bottom of the tower is employed.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed, and the vinyl ester component in the copolymer is saponified. 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. (1) Concentration of ethylene-vinyl ester copolymer in the 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) hours; 1 to 6 hours

[0038] The EVOH solution thus obtained is usually EV
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 OH. The alcohol content is preferably at least 70 parts by weight, more preferably at least 80 parts by weight. The alcohol content is preferably 10
It is not more than 00 parts by weight, more preferably not more than 500 parts by weight. By setting the content of alcohol to this range,
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 mixed solvent solution 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.

In the step 1 of the present invention, for example, a boiling point of 10 parts by weight based on 100 parts by weight of EVOH obtained as described above is used.
EVO containing 50 parts by weight or more of alcohol at 0 ° C. or less
The H solution was introduced into the device, and the alcohol was led out together with water by contacting with water in the device. From 0 to 10 parts by weight of the alcohol and 10 to 10 parts by weight of water per 100 parts by weight of EVOH.
This is a step of deriving the EVOH-containing composition containing up to 1000 parts by weight from the apparatus.

The above device is not particularly limited.
It may be brought into contact with water in a container or may be brought into contact with water in a kneading device such as an extruder. In order to process a large amount, it is preferable to contact with water in a container, and it is especially preferable to contact with water vapor.

That is, in a preferred embodiment of the step 1 in the present invention, the boiling point is 10 to 100 parts by weight of EVOH.
EVO containing 50 parts by weight or more of alcohol at 0 ° C. or less
H solution was introduced into a container, and brought into contact with water vapor in the container to derive the alcohol together with water vapor.
0 to 10 parts by weight of the alcohol based on 00 parts by weight,
This is a step of drawing out the EVOH-containing composition containing 10 to 1000 parts by weight of water from the container.

The method for bringing the EVOH solution introduced into the container into contact with steam in the container is not particularly limited, and may be any of a continuous method and 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. From the viewpoint 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, collected as an alcohol aqueous solution, purified if necessary, and reused.

If the amount of introduced steam is too small, the efficiency of removing the alcohol is poor, while if it is too large, it is disadvantageous in terms of cost. It is preferably 30 times, more preferably 0.5 to 10 times, and still more preferably 0.7 to 5 times. The steam to be brought into contact with the EVOH solution is steam 100
Although alcohol may be contained in an amount of 10 parts by weight or less with respect to parts by weight, it is preferable that water vapor contains no alcohol in order to efficiently remove the alcohol.

The temperature in the container 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 gels or becomes clogged in the container. The temperature is more preferably 110 ° C or higher, and still more preferably 120 ° C or higher. On the other hand, if the temperature in the container exceeds 150 ° C., EVOH may deteriorate. More preferably, it is 140 ° C. or lower.

If the pressure in the container is too low, the efficiency of removing alcohol is low, and if it is too high, the temperature of the EVOH solution in the container rises and thermal deterioration of the EVOH easily occurs. ６6 kg / cm ² , more preferably 1.5-5 kg / cm ² , even more preferably 2-4 kg / cm ² .

In this case, 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 a swollen paste state and gels while maintaining fluidity. It is possible to derive from the container without.

EVOH can be used under normal pressure, for example, at 60 to 70 ° C.
It dissolves in a methanol / water mixed solvent at a moderate temperature, but does not dissolve at normal pressure when the solvent is water only. However, it has been found that, in the presence of pressurized steam at a temperature of, for example, 100 ° C. or more, fluidity can be maintained even when EVOH contains 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 derived from the apparatus contains the above alcohol in an amount of 0 parts by weight per 100 parts by weight of EVOH.
It contains 10 to 10 parts by weight and 10 to 1000 parts by weight of water, and is discharged from the container in a fluidized state. EVOH
The content of the alcohol in the water-containing composition is preferably from 0 to 5
Parts by weight, more preferably 0 to 1 part by weight, even more preferably 0
０．１0.1 parts by weight. Since the alcohol content is low, the volatilization of methanol can be prevented in a later step such as precipitation, and the working environment and the surrounding environment can be preserved. Further, when washing the saponification catalyst residue and the like, even if the temperature of the washing liquid is increased, the pellets are unlikely to stick to each other, so that the washing temperature can be increased, and as a result, the washing speed can be increased.

The content of water in the EVOH-containing composition is from 10 to 1000 parts by weight. If the water content is less than 10 parts by weight, the fluidity in the container will be insufficient. Preferably 3
0 parts by weight or more, more preferably 50 parts by weight or more. On the other hand, if the water content exceeds 1000 parts by weight,
When it is deposited in the form of a strand, it is difficult to perform stable deposition, 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. Preferably not more than 500 parts by weight,
More preferably, it is 200 parts by weight or less.

The aqueous EVOH composition thus obtained is
Usually, it contains 0.1 to 5% by weight of an alkali metal salt in terms of metal, as well as by-product salts and other impurities.

The present invention relates to the EVOH obtained in the above step 1
The present invention relates to a method for producing an EVOH resin having a step (step 2) of supplying a water-containing composition to an extruder, melt-kneading the mixture, and then discharging the mixture from the extruder. Here, E derived from the apparatus in step 1
The method of supplying the VOH-containing composition to the extruder in step 2 is not particularly limited. The EVOH aqueous composition derived from the apparatus in step 1 may be cut into pellets and then supplied to the extruder in step 2, or may be supplied in a molten state without cutting.

First, the EVO derived from the apparatus in step 1
An embodiment in which the H-containing composition is cut into pellets and then supplied to the extruder in Step 2 will be described. Pellets can be produced by cutting the EVOH-containing composition derived from the apparatus of Step 1. The method of cutting is not particularly limited, and examples thereof include a method of extruding a molten EVOH-containing composition in a strand form into a coagulating liquid and coagulating it, followed by cutting, or a method of directly cutting 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, E
It is preferable that the water in the VOH is reduced by a kneader or the like in advance, 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 a conventional method in which a methanol solution of EVOH or a methanol / water mixed solution is extruded into a coagulating liquid, methanol is added to the coagulating liquid in order to prevent the discharged strand from floating in the coagulating bath before depositing. Although it was necessary to reduce the specific gravity of the coagulation solution, in the present invention, water containing no alcohol can be used for the coagulation bath because the coagulation rate is high,
Excellent in preserving the working environment and 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 in a short time. The temperature of the coagulating liquid is preferably from 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 pellets, the nozzle diameter is 2 to
5 mmφ (φ is a diameter; the same applies hereinafter) is preferable. FIG. 1 shows an example of a hot cutter used in the hot cutting method. 1 is a supply port of the EVOH aqueous composition, 2 is a die, 3
Is a rotary blade, 4 is a rotating shaft, 5 is a cutter box, 6 is a cooling water supply port, 7 is cooling water, 8 is a water film, 9 is a pellet discharge port, 1
0 is cooling water and pellets.

If the EVOH water-containing composition contains a large amount of water,
Since water is separated from the water-containing VOH composition and the separated water is discharged from the nozzle, stable cutting may be difficult. Therefore, as in the case of cutting the strand, it is preferable that the water in the EVOH is reduced by a kneader or the like in advance, and then cut by discharging from the nozzle.

The pellets thus obtained usually contain an alkali metal salt which is a residue of a saponification catalyst. If the content is large, quality problems such as coloring occur, so it is preferable to wash and remove the pellets. . 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 is usually 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 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. In the conventional method, the cleaning temperature is approximately 25 to 30 ° C., and one of the features of the present invention is that the cleaning temperature can be higher than that. Also,
The upper limit of the washing temperature is preferably 80 ° C. or less, more preferably 70 ° C. or less. By washing, the content of the alkali metal salt in the pellets is preferably adjusted to 0.05% by weight or less, more preferably 0.03% by weight or less in terms of metal.

In this case, the washing is not performed, and the process 2 is separately performed.
, It is also possible to carry out a washing operation in an extruder.
In addition, after performing the washing here, it is also possible to separately perform a washing operation in an extruder in Step 2 separately. The method of performing the washing operation in step 2 will be described later.

In order to improve the quality such as thermal stability, at least one additive selected from the group consisting of carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is added to the pellets. Is preferably added. There is no particular limitation on the method of adding such components,
A known method can be adopted. For example, there is a method in which pellets are immersed in an aqueous solution containing the additive to adsorb them.

Examples of the carboxylic acid include oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, propionic acid, lactic acid and the like. Of these, acetic acid and propionic acid are preferred from the viewpoints of cost, availability, and the like.
If the content of the carboxylic acid in the dried EVOH resin pellets of the present invention is too small, coloring may occur at the time of melt molding, and if too large, the interlayer adhesion may be insufficient. 10-5000 ppm is preferred. The lower limit of the carboxylic acid content is preferably at least 30 ppm, more preferably at least 50 ppm. Also,
The upper limit of the carboxylic acid content is preferably 1000 ppm or less, more preferably 500 ppm or less.

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. Examples include 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. If the content of the boron compound in the dried EVOH resin pellets of the present invention is too small, the effect of improving the thermal stability is small, and if it is too large, gelation may occur, resulting in poor moldability. 10 to 2000
ppm is preferable, and 50 to 1000 ppm is more preferable.

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 primary phosphate, a secondary phosphate, and a tertiary phosphate, and the cationic species 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 phosphate compound in the dried EVOH resin pellets of the present invention is 1 in terms of phosphate group.
Preferably it is ~ 1000 ppm. By adding in such a range, it is possible to suppress the coloring of the molded product and the occurrence of gel and butter. When the content of the phosphoric acid compound is less than 1 ppm, coloring during melt molding may be intensified. On the other hand, when the content exceeds 1000 ppm, gels and buttocks of the molded product may be easily generated.

Examples of the alkali metal salt include a monovalent metal aliphatic carboxylate, an aromatic carboxylate, a phosphate, and a metal complex. Examples include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, and sodium salt of ethylenediaminetetraacetic acid. Among them, sodium acetate, potassium acetate and sodium phosphate are preferred. The content of the alkali metal salt in the dried EVOH resin pellet of the present invention is 5% in terms of an alkali metal element.
~ 5000 ppm is preferred. More preferably, 20 to 1
000 ppm, even more preferably 30-750 pp
m.

Examples of the alkaline earth metal salt include a magnesium salt, a calcium salt, a barium salt, a beryllium salt and the like, and a magnesium salt and a calcium salt are particularly preferable. The anionic species of the alkaline earth metal salt is not particularly limited, but acetates and phosphates are preferred. The content of the alkaline earth metal in the dried EVOH resin pellets 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 is less than 10 ppm, the effect of improving long-run properties may be insufficient. Also,
If it exceeds 1000 ppm, coloring during melting of the resin may be intensified.

It is also possible to add the additives separately in Step 2 in an extruder without performing the operation of adding the above-mentioned additives. In addition, after performing the addition operation of the specific component here, it is also possible to separately add another component in the extruder in Step 2 separately. The method of adding in step 2 will be described later.

The method for washing the EVOH-containing composition pellets and the method for adding the additive to the EVOH-containing composition pellets are not particularly limited, and may be any of a batch processing container and a continuous processing container. Can also be used. Among them, a method of continuously supplying and treating pellets in a tower vessel is preferable from the viewpoint of productivity. At this time, the washing operation and the additive addition operation may be performed in the same processing tower, or may be performed in different processing towers.

Thus, the washing operation and / or
Alternatively, the obtained EVOH-containing composition pellets are charged into the extruder in Step 2 through the operation of adding additives.

Also, without being cut as described above,
It is also possible to supply the EVOH aqueous composition derived from the apparatus in step 1 to the extruder in step 2 in a molten state. In this case, it is preferable to perform the above-mentioned washing operation and component adding operation in step 2. Furthermore, EVOH
It is also possible to supply a crumb-like precipitate obtained by solidifying the paste in an irregular shape to the extruder in step 2.

Step 2 of the present invention is a step in which the EVOH-containing composition obtained through step 1 is supplied to an extruder, melt-kneaded, and then the composition is discharged from the extruder. Less than,
Step 2 will be described. As the extruder, a twin-screw extruder is preferable, and among them, a twin-screw extruder in which a screw rotates in the same direction is more preferable. Those having an L / D of 15 or more are preferred. The cylinder is preferably a block cylinder. As the screw, a segment type screw is preferable.

EVO before being charged into the extruder in step 2
The water content of the H water-containing composition is preferably 10% by weight or more, more preferably 30% by weight or more,
Even more preferably, it is 50% by weight or more. Further, the water content of EVOH before being charged into the extruder in step 2 is preferably not more than 1000% by weight,
0% by weight or less, more preferably 200% by weight
It is even more preferred that: When the water content of the EVOH water-containing composition before being introduced into the extruder is within the above range, it becomes possible to obtain EVOH in a molten state at a temperature lower than the melting point of EVOH in a dry state in the extruder. Thermal degradation of the EVOH in the machine can be suppressed and extrusion stability can be improved.

If the water content of the EVOH-containing composition before being charged into the extruder is less than 10% by weight, the effect of suppressing the thermal degradation of EVOH in the extruder may be insufficient. On the other hand, when the water content exceeds 1000% by weight, water is separated from the EVOH, whereby the feed amount becomes unstable, and as a result, the extrusion stability may be adversely affected.

The resin temperature in the extruder in step 2 was 7
The temperature is preferably from 0 to 170 ° C. 70 ℃ resin temperature
If it is less than 3, the EVOH-containing composition may not completely melt. When at least one additive selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is added, the effect of improving the dispersibility may be insufficient. is there. It is preferably at least 80 ° C, more preferably at least 90 ° C. If the resin temperature exceeds 170 ° C,
EVOH is susceptible to thermal degradation. Further, when the additive is added as an aqueous solution, the resin temperature is 170 ° C.
If the concentration exceeds the above range, the evaporation of water will become severe, and it may be difficult to mix the aqueous EVOH composition with the aqueous solution at a suitable aqueous solution concentration. It is preferably 150 ° C. or lower, more preferably 130 ° C. or lower. The method for adjusting the resin temperature is not particularly limited, but a method for suitably setting the temperature of the cylinder in the extruder is particularly preferable. Here, the resin temperature refers to a temperature detected by a temperature sensor installed in the extruder cylinder, and the detection point is near the discharge port at the tip of the extruder.

In the step 2, the saponification catalyst residue contained in the production of EVOH can be removed by washing in an extruder. Specifically, the EVOH aqueous composition is supplied to an extruder, and a cleaning liquid is injected from at least one portion of the extruder,
The resin can be washed, and the washing liquid can be discharged from at least one location downstream of the injection section. This method is preferable because it can be efficiently and space-savingly cleaned. In this case, the saponification catalyst residue contained in the EVOH supplied to the extruder is preferably an alkali metal salt.

The content of the alkali metal salt contained in the aqueous EVOH composition supplied to the extruder in Step 2 is preferably in the range of 0.1 to 5% by weight in terms of metal. More preferably, it is 0.2% by weight or more, and still more preferably 0.1% by weight.
5% by weight or more. It is more preferably at most 4% by weight, further preferably at most 3% by weight. If the content is less than 0.1% by weight, it is possible to manufacture the semiconductor device with a conventional cleaning method in a sufficiently small space, and it is not effective to adopt the manufacturing method of the present invention. On the other hand, when the content exceeds 5% by weight, an extruder having a large L / D is required to sufficiently perform washing, which is not preferable because the cost is increased.

In this case, the washed EVOH
The alkali metal salt contained in the resin is 0.05
It is preferable that the content be not more than weight%. More preferably 0.0
It is at most 4% by weight, more preferably at most 0.03% by weight. If it exceeds 0.05% by weight, EVOH
Is not preferred because the thermal stability is deteriorated.

The washing liquid used is not particularly limited as long as it can remove the saponification catalyst residue.
It is preferably an aqueous solution of an acid having a pKa of 3.5 or more at 25 ° C. When an aqueous solution of an acid having a pKa of less than 3.5 at 25 ° C. is used, the color resistance and interlayer adhesion of EVOH may be unsatisfactory. As such an acid having a pKa of 3.5 or more, a carboxylic acid is preferable, and acetic acid and propionic acid are particularly preferable in terms of cost and the like. The concentration of the acid when an aqueous solution of the acid is used is preferably 0.01 to 10 g / liter, and more preferably 0.1 to 10 g / liter.
1-2 g / liter. The injection amount of the washing liquid is preferably 0.1 to 100 liters per 1 kg of the charged resin weight.

The method of injecting the cleaning liquid is not particularly limited as long as the method can inject the cleaning liquid into the extruder.
A method of press-fitting using a plunger pump or the like can be given. The method of discharging the cleaning liquid is not particularly limited as long as the method can discharge the liquid from the extruder using a discharge unit disposed downstream of the injection unit, but a dehydration slit or a dehydration hole is preferable. No. In addition,
A plurality of injection parts or a plurality of discharge parts may be arranged.

Further, in the present invention, it is preferable to dehydrate or degas the EVOH in a water-containing state in the extruder after or without performing the above-mentioned washing in the extruder in step 2. Specifically, it is preferable to discharge water and / or steam from at least one portion of the extruder. The discharging method is not particularly limited, and examples include a method of discharging from a dehydrating slit, a dehydrating hole or a vent provided in a cylinder of the extruder. Preferable examples of the dewatering slit include a wedge wire type dewatering slit and a screen mesh type dewatering slit. Examples of the vent include a vacuum vent for removing water vapor under reduced pressure and an open vent for removing water vapor at normal pressure.

Of these, a dewatering slit or a dewatering hole is preferred. Since these can be discharged with both water and water vapor, it is possible to efficiently remove water from a resin having a high water content, and in this respect, generally, only water vapor can be discharged. Often more effective than vents. In addition, when moisture is discharged using the vent port, the resin tends to adhere to the vent port, and the adhered resin may deteriorate and enter the extruder. Is preferred. Further, when a dewatering hole is used, the molten resin may protrude from the hole, and from that point, it is preferable to use a dewatering slit.

The dehydrating means may be used alone, a plurality of the same type may be used, or different types may be used in combination. For example,
It is also possible to remove water to some extent from the resin having a high water content by using a dewatering slit, and then further remove moisture from the vent port on the downstream side.

The above-mentioned dehydration operation is performed to adjust the water content of the EVOH resin in the extruder and after the extrusion. In order to prevent the water content of the EVOH resin from becoming unnecessarily low, it is preferable to supply water to the extruder in addition to or without performing the dehydration operation described above. The method for supplying water to the extruder is not particularly limited, and examples thereof include a method of press-fitting with a plunger pump or the like.

The water content of the EVOH resin immediately after discharge from the extruder in step 2 is preferably 5 to 40% by weight,
Particularly preferred is 5% by weight. If the water content of the EVOH resin immediately after discharge from the extruder exceeds 40% by weight,
Water is separated from the VOH, and as a result, the strands discharged from the extruder may foam. Further, when the water content of the EVOH resin immediately after discharge from the extruder is less than 5% by weight, the effect of suppressing the deterioration of the EVOH due to heating in the extruder becomes insufficient, and as a result, the obtained EVOH resin has poor coloring resistance. May be unsatisfactory.

After washing the EVOH resin in the extruder as necessary and adjusting the water content, the carboxylic acid, the boron compound,
Various performances of the EVOH resin can be improved by adding at least one additive selected from a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt in the following preferable ranges. Each of the additives may be added alone, but a plurality of additives may be added simultaneously according to the embodiment. The effect of adding each of these components and the suitable amount of addition are as described in the description of treating the EVOH-containing composition pellets obtained in Step 1 already.

When the additives are contained in the EVOH resin, the additives are added in an extruder,
It can be kneaded in a very uniform state. By adopting such a configuration, it is possible to obtain an EVOH resin which is excellent in extrusion stability, coloring resistance, and long-running property, and in which generation of gel / bubbles and adhesion of the resin to a die are small. In addition, in the present invention, upon adding the additive to the EVOH resin in the extruder, the position at which the additive is added to the extruder is a position where the EVOH resin in the extruder is molten. Is preferable in that the effect of the above is sufficiently exhibited. In particular, it is preferable to add the above-mentioned additives to the EVOH resin in a hydrated and molten state. The extruder preferably has a kneading section, and it is particularly preferable that the additive is added at the kneading section of the extruder because the additive is easily mixed homogeneously.

Further, as a metal salt other than the above-mentioned alkali metal salts and alkaline earth metal salts, it is also possible to use a salt containing a metal of the fourth period of the periodic table.

The form of addition of the additives is not particularly limited. Examples thereof include a method of adding it as a dry powder in an extruder, a method of adding it as a paste impregnated with a solvent, a method of adding it in a state of being suspended in a liquid, and a method of dissolving it in a solvent and adding it as a solution. , Addition amount control, EVO
From the viewpoint of homogeneously dispersing the additive in the H resin,
A method in which the additive is dissolved in a solvent and added as a solution is particularly preferable. Such a solvent is not particularly limited,
Water is preferred from the viewpoints of solubility of the additive, cost advantages, ease of handling, safety of working environment, and the like. In addition, as an addition method, it is preferable to add the additive to the extruder from one place or two or more places.

When the additive is added as a solution to the EVOH resin, the lower limit of the amount of the solution is preferably at least 1 part by weight based on 100 parts by weight of the dry weight of the EVOH resin. It is more preferably at least 3 parts by weight, particularly preferably at least 5 parts by weight. The upper limit of the amount of the solution added is a dry weight of EVOH of 1
The amount is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and particularly preferably 20 parts by weight or less based on 00 parts by weight. If the amount of the solution is less than 1 part by weight, the concentration of the solution needs to be increased, and the effect of improving the dispersibility by adding the additive may be reduced. On the other hand, if it exceeds 50 parts by weight, it becomes difficult to control the water content of EVOH, and
Water may be separated from OH.

In a conventional treatment method in which EVOH resin pellets are impregnated with a solution of the above-mentioned additives, etc.
Although it was difficult to obtain a good quality product such as crumb-like precipitates of the VOH resin, the present invention makes it possible to uniformly add the additives to the EVOH resin in such a form, and to achieve stable quality. Can be obtained.

The method of pelletizing the EVOH resin discharged from the extruder in Step 2 is not particularly limited, but a method of extruding the resin composition from a die into a strand in a coagulation bath and cutting it into an appropriate length is used. Is exemplified. From the viewpoint of easy handling of the pellet, the diameter of the die is 2 to
5 mmφ is preferred, and the strand is preferably cut to a length of about 1 to 5 mm. Also, a hot cut method or an underwater cut method is exemplified as a suitable method.

The obtained pellets are usually subjected to a drying step. The moisture content of the dried EVOH resin pellets is preferably 1.0% by weight or less, more preferably 0.5% by weight. The drying method is not particularly limited, but a stationary drying method, a fluidized drying method and the like are preferred, and a multi-stage drying step combining several drying methods can be employed. Among them, a method in which drying is performed by a fluidized drying method first, and then drying by a static drying method is preferable.

In the case of the conventional treatment method in which EVOH resin pellets are immersed in a treatment solution containing the above-mentioned additives, the water content of the treated EVOH resin pellets is usually about 40 to 70% by weight. However, in the case of the treatment method of the present invention, it is possible to arbitrarily adjust the water content of the EVOH resin immediately after discharge from the extruder. The water content immediately after discharge from the extruder is preferably 5 to 40% by weight. Therefore, it is possible to obtain pellets having a smaller moisture content than the conventional method. Such pellets are suitable from the viewpoint that the energy consumption in the drying process can be reduced.

In particular, pellets having a water content of more than 40% by weight may cause fusion of the pellets when the drying temperature is set to 100 ° C. or higher. From this point of view,
The processing method of the present invention in which EVOH is melted in an extruder and the additive is added in the extruder is suitable.

It is also possible to blend the EVOH resin pellets obtained by the above method with EVOH having different degrees of polymerization, ethylene content and saponification degree, and to carry out melt molding.
Also, other various plasticizers, lubricants, stabilizers, surfactants, coloring agents, ultraviolet absorbers, antistatic agents, desiccants,
It is also possible to add an appropriate amount of a crosslinking agent, a metal salt, a filler, a reinforcing agent such as various fibers, and the like.

The thus obtained EVOH resin pellets are melt-molded into films, sheets, containers, pipes,
It is molded into various molded articles such as fibers. Used for various packaging applications.

[0098]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Note that “%” and “parts” are based on weight unless otherwise specified.

(1) Measurement of water content 20 g of EVOH as a sample was placed in a well-dried weighing bottle, dried with a hot air drier at 120 ° C. for 24 hours, and the following formula (from the weight change of EVOH before and after drying) was obtained. The water content of EVOH was determined using 1). Water content (% by weight) = (weight before drying−weight after drying) / weight before drying × 100 (1)

(2) Quantification of added trace components Quantification was performed according to the following method. (2-a) Quantification of Carboxylic Acid 20 g of dry pellets as a sample were put in 100 m of deionized water.
and extracted by heating at 95 ° C. for 6 hours. The obtained extract was subjected to 1/50 of phenolphthalein as an indicator.
Neutralization titration was performed with a specified aqueous NaOH solution to obtain a carboxylic acid content. (2-b) Determination of Alkali Metal Salt and Alkaline Earth Metal Salt 10 g of a dry pellet 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. The column is ICS-C25 manufactured by Yokogawa Electric Corporation.
The eluent was an aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid. In the determination, a calibration curve prepared with each aqueous metal chloride solution was used. Thus, the amount of the alkali metal salt and the amount of the alkaline earth metal salt in the dried pellets were obtained in terms of metal. (2-c) Determination of Boron Compound An aqueous solution of Na ₂ CO ₃ was added to the dried pellets as samples, and the samples were incinerated at 600 ° C. in a platinum crucible. Hydrochloric acid was added to the obtained sample to dissolve it, and the content of the boron compound was obtained in terms of boron by ICP emission spectroscopy. (2-d) Determination of Phosphoric Acid Compound 10 g of a dry pellet 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 to determine the amount of phosphate ions. Column, Inc.
Use ICS-A23 manufactured by Yokogawa Electric Corp.
An aqueous solution containing mM sodium carbonate and 1.0 mM sodium bicarbonate was used. In the determination, a calibration curve prepared with a phosphoric acid aqueous solution was used. From the amount of the phosphate ion thus obtained, the content of the phosphate compound was obtained in terms of a value of a phosphate group.

(3) Melt index (MI) Measured under the conditions of a temperature of 190 ° C. and a load of 2160 g using a melt indexer according to ASTM-D1238.

Example 1 FIG. 2 schematically shows the steps. Ethylene content 32 mol%,
EVOH containing 100 parts by weight of EVOH having a saponification degree of 99.5 mol%, 100 parts by weight of methanol, 50 parts by weight of water and 2 parts by weight of sodium acetate in terms of sodium.
The solution was supplied from the EVOH solution supply pipe 21 to a tower diameter of 0.3.
m, 52 kg / hr at the top of the tray column 11 with 10 plates
And steam is blown at 86 kg / hr from the steam supply pipe 20 to the lowermost stage of the tray column to produce EVO.
The H solution and steam were brought into countercurrent contact in the tray column. The temperature in the tower was 130 ° C., and the pressure in the tower was 3 kg / cm ² . Methanol vapor and water vapor are distilled off from the top of the tray column through a gas discharge pipe 22, and these are condensed into a condenser 12.
And collected as a methanol aqueous solution. The EVOH aqueous composition was continuously extracted from the bottom of the tray column through the aqueous composition discharge pipe 23. 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 50 having a diameter of 50 mm and a length of 660 mm (L / L).
D = 13.2) to the kneader 13 at 41 kg / hr. The rotation speed of the screw at this time was 100 rpm. The EVOH hydrate composition obtained from the discharge port is EVO
It contained 0.03 parts by weight of methanol, 63 parts by weight of water (water content 39%), and 1.2 parts by weight of sodium acetate in terms of sodium with respect to 100 parts by weight of H. Subsequently, this 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 with a hot cutter 14 having four blades to obtain pellets (A). I got The rotation speed of the cutter blade was 1200 rpm.

The obtained pellets (A) were passed through a pellet supply pipe 24 into a tower-type processor 1 having a diameter of 0.8 m and a height of 4 m.
5 was fed to the top of the column at 33 kg / hr. A 0.5 g / L aqueous solution of acetic acid (50 ° C.) was charged at 500 L / hr from the solution supply pipe 26 to the lower part of the processor, and the pellets and the aqueous solution of acetic acid were brought into countercurrent contact with each other in the processor. The aqueous solution of acetic acid was discharged from the upper part of the processor through a solution discharge pipe 25, and the washed pellets (B) were continuously taken out from the bottom of the processor through a pellet discharge pipe 27.
The pellet (B) had a moisture content of 39%, and sodium acetate remained in an amount of 0.002% by weight in terms of sodium. Further, the pellets did not fuse with each other during the washing.

Next, the pellet (B) was charged into the twin screw extruder 16. The resin temperature of the discharge port was set to 100 ° C., and the processing liquid composed of acetic acid / boric acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate aqueous solution was supplied from the trace component addition section 31 shown in FIG. Was added. EV
OH input per unit time is 10.7kg / hr
(Including the weight of water contained), the amount of the processing solution charged per unit time was 0.65 L / hr, and the composition of the processing solution was 4.3 g / L of acetic acid, 15 g / L of boric acid, and acetic acid. The aqueous solution contained 4.6 g / L of sodium, 3.0 g / L of magnesium acetate tetrahydrate, and 1.4 g / L of potassium dihydrogen phosphate. The specifications of the twin screw extruder are shown below. Type Twin screw extruder L / D 45.5 Bore 30mmφ Screw Fully meshing in the same direction Rotation speed 300rpm Cylinder temperature 100 ° C Die temperature 105 ° C Die hole number 5 holes (3mmφ)

FIG. 3 shows details of the twin-screw extruder. The extruder includes a raw material supply section 29, a liquid removal section 30, a trace component addition section 31
And a wedge wire type dewatering slit 33 was arranged in the liquid removing part. The screw was a combination of a full flight screw 34 and a reverse flight screw 35 as shown in the figure. Further, a temperature sensor 32 was provided at the end of the cylinder.

The molten EVOH treated by the extruder
The resin was cut with a hot cutter 17 to obtain a pellet (C). The water content of the pellet (C) was 20% by weight.
The obtained pellets (C) were subjected to 90
The resulting product was dried at 150 ° C. for 15 hours, and subsequently dried at 105 ° C. for 15 hours using the stationary dryer 19, and as a result, the water content was 0.2% by weight. The content of acetic acid in the EVOH resin pellet (D) after drying is 300 ppm, the content of boron compound is 270 ppm in terms of boron, the content of phosphoric acid compound is 98 ppm in terms of phosphate, and the content of alkali metal salt is potassium. The salt was 40 ppm in terms of metal, the sodium salt was 130 ppm in terms of metal, and the content of alkaline earth metal salt was 35 ppm in terms of magnesium salt in terms of metal.
MI was 1.5 g / 10 min.

Example 2 The pellet (A) of Example 1 was prepared by using 0.8 m in diameter and 4 m in height.
Was supplied at a rate of 33 kg / hr. From the lower part of the processing unit, a processing solution (50% aqueous solution of acetic acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate)
C) was added at 500 L / hr. The composition of the treatment liquid is an aqueous solution containing 1.7 g / L of acetic acid, 0.67 g / L of sodium acetate, 1.84 g / L of magnesium acetate tetrahydrate, and 0.77 g / L of potassium dihydrogen phosphate. Met. Treated pellets were continuously removed from the bottom of the processor. The water content of the pellets was 39%.

Next, the pellets were charged into a twin-screw extruder having the same configuration as that shown in FIG. 3 except that the screw in the trace component addition section was changed to a full flight screw. The resin temperature at the discharge port is 100 ° C., and the amount of EVOH charged per unit time is 10.7 kg / hr (including the weight of contained water).
Nothing was added from the trace component addition section. The water content of the EVOH resin pellets after discharge from the extruder was 18% by weight. The obtained pellet was dried at 90 ° C. for 15 hours using a fluidized drier, and subsequently dried at 105 ° C. using a stationary drier.
As a result, the water content was 0.2% by weight. The content of acetic acid in the EVOH resin pellets after drying is 200 ppm, the content of the phosphoric acid compound is 90 ppm in terms of phosphate, and the content of the alkali metal salt is 35 ppm in terms of metal in terms of potassium salt and 120 ppm in terms of metal in terms of sodium salt.
ppm, and the content of alkaline earth metal salt was 60 ppm in terms of metal of magnesium salt. MI was 12 g / 10 min.

Example 3 To 100 parts by weight of EVOH having an ethylene content of 35 mol% and a saponification degree of 99.5 mol%, 100 parts by weight of methanol, 50 parts by weight of water and 1.5 parts by weight of sodium acetate were converted into sodium. Containing EVOH solution with a tower diameter of 0.3
m, a continuous supply of 52 kg / hr from the uppermost stage of a tray column having 10 stages, steam was blown from the lowermost stage at 86 kg / hr, and the EVOH solution and the steam were brought into contact with each other in countercurrent.
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 continuously extracted from the bottom of the tower. The EVOH-containing composition contained 0.04 parts by weight of methanol, 105 parts by weight of water and 1.5 parts by weight of sodium acetate in terms of sodium based on 100 parts by weight of EVOH.

Next, the EVOH-containing composition was supplied to a twin-screw extruder shown in FIG. The amount of EVOH charged per unit time is 50 kg / hr (including the weight of contained water)
Met. A 0.5 g / L acetic acid aqueous solution was added at a rate of 600 L / hr from the washing liquid adding section 37. In addition, a treatment liquid composed of acetic acid / boric acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate aqueous solution was added from the trace component addition section 39. The input amount per unit time of the treatment liquid was 2.4 L / hr, and the composition of the treatment liquid was 5.0 acetic acid.
g / L, boric acid at 15 g / L, and sodium acetate at 4.6.
g / L, 3.0 g / L of magnesium acetate tetrahydrate,
It was an aqueous solution containing 1.4 g / L of potassium dihydrogen phosphate. The specifications of the twin screw extruder are shown below. Type Twin screw extruder L / D 45.5 Bore 47mmφ Screw Fully meshing in the same direction Rotation speed 450rpm Cylinder temperature 95 ° C Die temperature 120 ° C Die hole number 5 holes (φ3mm)

FIG. 4 shows details of the twin-screw extruder. The extruder includes a raw material supply section 36, a cleaning liquid addition section 37, a liquid removal section 38,
A wedge wire type dewatering slit 41 was provided in the liquid removing part, which was constituted by a minor component addition part 39. The screw was a combination of a full flight screw 42 and a reverse flight screw 43 as shown in the figure, and a seal ring 44 was attached. Temperature sensor-4 at cylinder end
0 was placed.

The molten EVOH treated by the extruder
The resin was cut with a hot cutter to obtain a pellet (C ′). The water content of the EVOH resin pellets after discharge from the extruder is 2
It was 3% by weight. The obtained pellets were dried at 90 ° C. for 15 hours using a fluidized drier, and subsequently dried at 105 ° C. for 15 hours using a stationary drier. As a result, the water content was 0.1%.
% By weight. The content of acetic acid in the EVOH resin pellet (D ') after drying is 320 ppm, the content of the boron compound is 270 ppm in terms of boron, the content of the phosphate compound is 100 ppm in terms of phosphate, and the content of the alkali metal salt is Potassium salt is 38 ppm in metal conversion, sodium salt is 170 ppm in metal conversion, and the content of alkaline earth metal salt is 40 p in magnesium salt conversion.
pm. MI was 1.7 g / 10 min.

Comparative 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 with respect to 100 parts by weight of EVOH having an ethylene content of 32 mol% and a saponification degree of 99.5 mol%. The solution is extruded from a metal plate having a circular opening into a coagulation bath composed of a 10% aqueous methanol solution to be coagulated into strands, and cut with a strand cutter to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. Was. Methanol vapor was volatilized from the coagulation bath, and the concentration of the surrounding methanol was 180 ppm, which was not preferable in the working environment.

The obtained pellets were placed in the same manner as in Example 1 to the top of a tower-type treatment device having a diameter of 0.8 m and a height of 4 m, and charged to a top of 33 kg / kg.
hr (including the weight of the contained aqueous methanol solution), a 0.5 g / L aqueous acetic acid solution (50 ° C.) is charged from the lower part of the processor at 500 L / hr, and the bottom of the processor is washed. The pellets were continuously removed. At this time, defective removal of the pellets caused by fusion of the pellets frequently occurred, and continuous operation was difficult. The resulting pellets had a moisture content of 55% and sodium acetate of 0.008% by weight in terms of sodium remained.

3.5 kg of the thus obtained EVOH resin pellets (water content: 55% by weight) were mixed with 0.4 g of acetic acid / 0.4 g of acetic acid.
L, sodium acetate 0.4 g / L, magnesium acetate 0.3 g / L, potassium dihydrogen phosphate 0.1 g / L, and 6 L of an aqueous solution containing boric acid 0.7 g / L were immersed at 25 ° C. for 6 hours. After immersion, the solution was drained, and the obtained EVOH resin pellets (water content: 55% by weight) were heated to 80 ° C. using a fluidized drier.
For 15 hours, followed by drying at 100 ° C. for 24 hours using a stationary dryer, and dried pellets (water content: 0.3%)
I got

The obtained dried EVOH resin pellets had a acetic acid content of 300 ppm, a boron compound content of 270 ppm in terms of boron, a phosphoric acid compound content of 100 ppm in terms of phosphate groups, and an alkali metal salt content. The amount was 40 ppm in terms of metal for potassium salt and 130 ppm in terms of metal for sodium salt, and the content of alkaline earth metal was 36 ppm in terms of metal for magnesium salt. MI was 1.5 g / 10 min.

[0118]

According to the present invention, it is possible to provide a method for producing an EVOH resin capable of efficiently removing alcohol without deteriorating the working environment and the surrounding environment. Also,
It is also possible to provide a method for producing EVOH resin pellets, which can be produced stably from the EVOH resin, can be stably produced, and have a high washing speed. The EVOH resin pellets thus obtained have good extrusion stability and heat stability (long run property).

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration of a hot cutter used in the present invention.

FIG. 2 is a schematic view of the steps of Example 1.

FIG. 3 is a diagram showing a configuration of a twin-screw extruder used in Example 1.

FIG. 4 is a diagram illustrating a configuration of a twin-screw extruder used in a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Supply port of EVOH water-containing composition 2 Die 3 Rotating blade 4 Rotating shaft 5 Cutter box 6 Cooling water supply port 7 Cooling water 8 Water film 9 Pellet outlet 10 Cooling water and pellets 11 Shelf tower 12 Condenser 13 Kneader 14 17 Hot Cutter 15 Tower Type Processor 16 Twin Screw Extruder 18 Fluid Dryer 19 Stationary Dryer 20 Steam Supply Pipe 21 EVOH Solution Supply Pipe 22 Gas Discharge Pipe 23 Hydrous Composition Discharge Pipe 24 Pellet Supply Pipe 25 solution discharge pipe 26 solution supply pipe 27 pellet discharge pipe 28 kneader liquid discharge port 29 raw material supply section 30 liquid removal section 31 trace component addition section 32 temperature sensor 33 dehydration slit 34 full flight screw 35 reverse flight screw 36 raw material Supply part 37 Cleaning liquid addition part 38 Drainage part 39 Trace component addition part 40 Degree sensor 41 dewatering slit 42 full-flight screw 43 reverse-flight screw 44 sealing ring

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) // C08L 29:04 C08L 29:04 S (72) Inventor Yukihiro Ohara 1-2-1 Kaigandori, Okayama City, Okayama Prefecture No. Kuraray Co., Ltd. (72) Inventor Masao Hikasa 1621 Sakurazu, Kurashiki-shi, Okayama Prefecture Kuraray Co., Ltd. (72) Inventor Hiroshi Kawai 1621 Sakurazu, Kurashiki-shi, Okayama Prefecture F-term (reference) 4F070 AA13 AA26 AB09 AB13 AE02 AE03 BA07 BB03 BB05 DA21 DB01

Claims (20)

[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 was introduced into the apparatus, and the alcohol was brought out together with water in the apparatus by bringing it into contact with water. Deriving a water-containing ethylene-vinyl alcohol copolymer composition containing 0 to 10 parts by weight of the alcohol and 10 to 1000 parts by weight of water from the above-described apparatus, based on 100 parts by weight of the ethylene-vinyl alcohol copolymer ( Step 1); and supplying the water-containing composition of ethylene-vinyl alcohol copolymer to an extruder, melt-kneading, and then discharging the copolymer from the extruder (Step 2). For producing an ethylene-vinyl alcohol copolymer resin. 2. The ethylene-vinyl alcohol copolymer has an ethylene content of 3 to 70 mol% and a saponification degree of 80.
The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, which is at least mol%. 3. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the alcohol is methanol. 4. In step 1, the ethylene-vinyl alcohol copolymer solution is introduced into a vessel, and the alcohol is taken out together with water vapor by contact with water vapor in the vessel. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of claims 1 to 3, wherein a product is discharged from the container. 5. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 4, wherein the ethylene-vinyl alcohol copolymer solution is continuously introduced into a tower-shaped vessel, and brought into contact with steam in the vessel. . 6. 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 solution and the steam are brought into countercurrent contact with each other. 6. The ethylene-vinyl alcohol copolymer hydrous composition is led out from the lower part of the tower, and the alcohol is led out from the upper part of the tower together with steam.
3. The method for producing an ethylene-vinyl alcohol copolymer resin according to item 1. 7. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein in step 2, the resin in the extruder has a melting temperature of 70 to 170 ° C. 8. The process according to claim 1, wherein the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight.
A method for producing an ethylene-vinyl alcohol copolymer resin according to any one of claims 1 to 7. 9. The process according to claim 1, wherein the water content of the resin in the extruder is adjusted by supplying insufficient water to the extruder or removing excess water from the extruder.
8. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of 8. 10. In the step 2, at least one additive selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is blended and melt-kneaded in the extruder. 10. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of 1 to 9. 11. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 10, wherein the additive is blended in an aqueous solution. 12. In step 2, a cleaning liquid is injected into the extruder, and at least one of the cleaning liquid downstream of an injection part of the cleaning liquid is injected.
The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of claims 1 to 11, wherein the cleaning liquid is discharged from the portion to remove the saponification catalyst residue. 13. The extruder of step 2, wherein pellets obtained by cutting the ethylene-vinyl alcohol copolymer hydrated composition derived from the apparatus in step 1 are supplied. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of the above. 14. The ethylene-vinyl alcohol copolymer according to claim 13, wherein the pellets obtained by cutting are immersed in a washing liquid to remove saponification catalyst residues, and then supplied to the extruder in step 2. Method of manufacturing resin. 15. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 14, wherein the resin is continuously washed in a tower type vessel. 16. The pellets obtained by cutting are mixed with at least one of a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt.
Immersed in an aqueous solution containing seed additives, adding the additives to the pellets, and then feeding the extruder in Step 2;
A method for producing the ethylene-vinyl alcohol copolymer resin according to any one of claims 13 to 15. 17. The extruder according to claim 1, wherein the water-containing composition of the ethylene-vinyl alcohol copolymer in the molten state derived from the apparatus in the step 1 is supplied to the extruder in the step 2 without cutting. A method for producing the ethylene-vinyl alcohol copolymer resin according to any one of the above. 18. After the ethylene-vinyl alcohol copolymer hydrate composition is supplied to the extruder in Step 2 without cutting, a cleaning liquid is injected into the extruder, and at least one of the downstream parts of the cleaning liquid injection part is provided. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 17, wherein the cleaning liquid is discharged from the portion to remove the saponification catalyst residue. 19. An ethylene-vinyl alcohol copolymer obtained by discharging the ethylene-vinyl alcohol copolymer resin obtained by the method according to claim 1 from the extruder in step 2, and cutting the resin. Method for producing resin pellets. 20. The method for producing an ethylene-vinyl alcohol copolymer resin pellet according to claim 19, wherein the pellet is dried until the moisture content becomes 1% by weight or less after cutting.