JP2001098077A - Method for producing ethylene/vinyl alcohol copolymer resin and production of pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove saponification catalyst residues from a water- containing molten or semi-molten ethylene/vinyl alcohol copolymer (EVOH) resin by feeding the EVOH resin into an extruder, pouring a washing fluid into the extruder to wash the resin, and discharging the washing fluid from at least one port downstream of the pour port of the washing fluid. SOLUTION: A water-containing molten or semi-molten EVOH is sent forward by means of a full-flighted section 5, and water as a washing fluid is fed from a washing fluid pour port 2. Next, the EVOH is dehydrated by squeezing excessive water at a fluid removal section 3. During the removal of the excessive water, saponification catalyst residues in the production process are removed by washing. The temperature of the molten resin in the extruder is kept in the range of 70-170 deg.C. The water content of the molten resin in the extruder is adjusted so that the water content of the resin just after discharge from the extruder may be 5-40 wt.%, and the extrudate is cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently removing a saponification catalyst residue contained in an ethylene-vinyl alcohol copolymer resin (hereinafter also referred to as "EVOH") during the production thereof, and a method for producing pellets thereof. About the method.

[0002]

2. Description of the Related Art Ethylene-vinyl alcohol copolymers have been widely used for food packaging because of their high gas barrier properties and excellent oil and organic solvent resistance, fragrance retention and transparency. For food packaging, various molding methods such as a film formed by extrusion, a bottle formed by blow molding, and various packs formed by vacuum forming are employed. In such various forming methods, a resin pellet is supplied to an extruder, and once melted, a forming process is started. In this case, if the saponification catalyst residue contained in the resin during the production remains in the polymer, the thermal stability may be deteriorated.

Conventionally, in order to remove the saponification catalyst residue from the polymer, resin pellets are put into a washing vessel, contacted with a washing liquid (water) in a solid state, and extracted from the inside of the resin pellets by diffusion ( Japanese Patent Publication 55-19
242).

[0004] However, the conventional cleaning method has a problem that it takes time and requires a large cleaning device and space.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention efficiently removes a saponification catalyst residue contained in the production of an ethylene-vinyl alcohol copolymer resin and can wash it in a small space. An object of the present invention is to provide a method for producing an ethylene-vinyl alcohol copolymer resin and a method for producing pellets thereof.

[0006]

In order to achieve the above object, a method for producing an ethylene-vinyl alcohol copolymer resin according to the present invention comprises removing a saponification catalyst residue contained in the production of an ethylene-vinyl alcohol copolymer resin. A method of removing, supplying the resin to an extruder, injecting a cleaning liquid from at least one location of the extruder, washing the resin,
The cleaning liquid is discharged from at least one location downstream of the cleaning liquid injection part. According to this method,
EVO in a molten or semi-molten state with water in an extruder
H can efficiently remove the saponification catalyst residue. Also,
EVOH can be cleaned in a small space. Further, since the EVOH can be washed at a relatively low temperature, deterioration of the polymer can be prevented.

Next, in the method for producing ethylene-vinyl alcohol copolymer resin pellets of the present invention, an ethylene-vinyl alcohol copolymer resin containing a saponification catalyst residue is supplied to an extruder, and at least one portion of the extruder is provided. The washing liquid is injected from the extruder, and the resin is washed, the washing liquid is discharged from at least one place downstream of the injection part of the washing liquid, and then discharged from the extruder and cut. According to this method, in addition to the first method, an efficient EV
OH pellets can be produced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the ethylene-vinyl alcohol copolymer supplied to an extruder preferably has a water content of 0.5 to 70% by weight.

In the present invention, the residue of the saponification catalyst contained in the ethylene-vinyl alcohol copolymer supplied to the extruder is an alkali metal ion, and the content of the ion is 0.1 to 5 wt. % Is preferable.

In the present invention, the content of the alkali metal ion contained in the washed ethylene-vinyl alcohol copolymer is preferably 0.05% by weight or less in terms of metal.

[0011] In the present invention, the cleaning solution is at 25 ° C.
Is preferably an aqueous solution of an acid having a pKa of 3.5 or more.

In the present invention, the ethylene content of the ethylene-vinyl alcohol copolymer is 3 to 70 mol%.
Is preferably within the range.

In the present invention, the degree of saponification of the ethylene-vinyl alcohol copolymer is preferably in the range of 80% to 100%.

In the present invention, the cleaning liquid is discharged
It is preferably at least one means selected from a dewatering slit and a dewatering hole.

In the present invention, the resin melting temperature in the extruder is preferably in the range of 70 to 170 ° C.

In the present invention, after the cleaning liquid is discharged, dehydration or degassing is further performed, and the water content is adjusted so that the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight. Is preferred.

Further, in the present invention, the resin is formed into a resin in an extruder by at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts.
It is preferred to add seed additives.

In the present invention, after the washing liquid is discharged, dehydration or degassing is further performed, and the water content is adjusted so that the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight. After the addition of the additive, it is preferable that the resin composition is discharged from the extruder and cut.

In the present invention, it is preferable that after the resin composition is cut, it is dried until the water content becomes 1% by weight or less.

Next, the present invention will be described with reference to the drawings. FIG.
FIG. 4 is an explanatory view showing a schematic process chart of an embodiment of the cleaning method of the present invention. EVOH is supplied from the raw material supply port 1 of the barrel 11 of the twin screw extruder 10. The hydrous and molten or semi-molten EVOH is sent forward by the full flight screw portion 5 a of the screw 12, and water as a cleaning liquid is supplied from the cleaning liquid addition section 2. Next, the mixture is kneaded in the reverse flight screw section 6. Next, the water is sent forward by the full flight screw section 5b, and excess water is squeezed out and dewatered in the liquid removing section 3. During the dehydration of the excess water, the saponification catalyst residue in the production process is washed and desorbed.
Thereafter, the liquid is discharged from a discharge port (not shown) through the seal ring portion 7 and the full flight screw portion 5c. 4
Is a temperature sensor for detecting and controlling the temperature of the EVOH.

Next, FIG. 2 is an explanatory view showing a schematic process chart of an embodiment in which a trace component is added after washing in the method of the present invention. EVOH is supplied from a raw material supply port 23 of a barrel 21 of the twin screw extruder 20. The EVOH in the hydrated and molten or semi-molten state is sent forward by the full flight screw portion 28a of the screw 22, and the washing liquid adding portion 24
Is supplied as washing liquid. Next, it is kneaded in the reverse flight screw portion 29a. Next, it is sent forward by the full flight screw section 28b,
In a, excess water is squeezed and dehydrated. During the dehydration of the excess water, the saponification catalyst residue in the production process is washed and desorbed. Thereafter, the water is sent forward by the seal ring section 30 and the full flight screw section 28c, and further dewatered or degassed in the liquid removing section 25b. Next, an additive is added from the trace component adding section 26, kneaded by the reverse flight screw section 29b, and discharged through a discharge port (not shown) through the full flight screw section 28d. 27 is a temperature sensor for detecting and controlling the temperature of the EVOH.

The EVOH used in the present invention is preferably obtained by saponifying an ethylene-vinyl ester copolymer. The ethylene content is 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 20 to 55 mol%, Is preferably 25 to 55 mol%. Further, the degree of saponification of the vinyl ester component is from 80 mol% to 100 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 having water solubility, and such EVOH aqueous solution has excellent barrier properties and coating film moldability, and is used as an excellent coating material.

EVO having a saponification degree of 80 to 95 mol%
H is suitably used for improving melt 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, the above-mentioned EVOH having an ethylene content of 3 to 20 mol% and EVOH having a saponification degree of 80 to 95 mol% can be used in a conventional manner. It was difficult to extrude the methanol solution into a coagulation bath in the form of strands to precipitate, it was difficult to produce stable pellets, and it was also difficult to extract the saponification catalyst residue from the pellets to the outside by diffusion. . The present invention is significant for EVOH from the viewpoint of stable production of pellets and uniform addition of acidic substances and metal salts to the pellets.

If the ethylene content of EVOH is less than 3 mol%, melt moldability is poor, and water resistance, hot water resistance, and gas barrier properties under high humidity may decrease. On the other hand, if it exceeds 70 mol%, the barrier properties, printability and the like will be insufficient.
If the degree of saponification is less than 80 mol%, the barrier properties, coloring resistance and moisture resistance will be 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: Alcohols are preferred, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl ester and ethylene-vinyl ester copolymer can also be used. As the alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.

Catalyst: 2,2-azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), 2,2-azobis- (4-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 and vinyl esters of fatty acids (vinyl propionate, vinyl pivalate, etc.) can also be used. EVOH can contain 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component. 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. (1) Temperature: 20 to 90 ° C, preferably 40 to 70 ° C. (2) Time: 2 to 15 hours, preferably 3 to 11 hours. (3) Polymerization rate: 10 to 90 based on the charged vinyl ester
%, 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, it is 10 to 60 mol%, more preferably, 20 to 55 mol%, and most preferably, 25 to 55 mol%. In addition to ethylene and vinyl ester, monomers copolymerizable therewith, such as propylene and isobutylene. , Α
Α-olefins such as octene and α-dodecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid and itaconic acid or anhydrides, salts or mono- or dialkyl esters thereof; acrylonitrile, methacrylonitrile Amides such as acrylamide and methacrylamide; olefinsulfonic acids such as ethylenesulfonic acid, allylsulfonic acid and methallylsulfonic acid or salts thereof; alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride, and chloride It is also possible to coexist a small amount of vinylidene or the like.

After the polymerization for a predetermined time has reached a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation. As a method of driving out unreacted vinyl ester from the ethylene-vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously supplied at a constant rate from the top of a tower filled with Raschig rings, A method in which an organic solvent vapor such as methanol is blown from a lower portion, a mixed vapor of an organic solvent such as methanol and an unreacted vinyl ester is distilled off from the top of the tower, and the copolymer solution from which the unreacted vinyl ester is removed is removed from the bottom of the tower. Is adopted.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester component in the copolymer. The saponification method 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; It is preferable to neutralize the EVOH after the reaction for 1 to 6 hours as necessary.

The present invention is a method for removing a saponification catalyst residue from EVOH in an extruder, but the shape of EVOH before being charged into the extruder is not particularly limited. Pellets obtained by cutting a strand precipitated in a coagulation bath are preferably used, and a crumb-like precipitate obtained by solidifying an EVOH paste in an irregular shape can also be used. Alternatively, the EVOH paste can be directly fed into the extruder.

The lower limit of the water content of EVOH before being charged into the extruder is preferably 0.5% by weight or more, and preferably 5% by weight or more.
%, More preferably at least 7% by weight. Further, the upper limit of the water content of EVOH before being charged into the extruder is preferably 70% by weight or less, more preferably 60% by weight or less, and further preferably 50% by weight or less. When the water content of the EVOH before being charged into the extruder is within the above range, the EVOH in a dry state is formed in the extruder.
It is possible to obtain EVOH in a molten state at a temperature lower than the melting point of, and it is possible to suppress thermal degradation of EVOH in the extruder and to improve extrusion stability.

When the water content of EVOH before being charged into the extruder is less than 0.5% by weight, the EV
The effect of suppressing thermal degradation of OH may be insufficient. If the water content exceeds 70% by weight, the resin and water contained in the resin may easily undergo phase separation in the resin composition composed of EVOH. If the resin and the water contained in the resin undergo phase separation, the resin surface becomes wet and the friction increases, which may easily cause a bridge in the hopper of the extruder. May adversely affect the productivity of the product pellets.

The method for adjusting the water content of EVOH before being charged into the extruder is not particularly limited. To increase the water content, a method of spraying water on the resin, a method of immersing the resin in water, a method of bringing the resin into contact with water vapor, and the like can be mentioned. When reducing the water content, an appropriate drying method may be used, for example, a method of drying using a fluidized hot air dryer or a stationary hot air dryer, but from the viewpoint of reducing drying spots. It is preferable to use a fluidized hot air dryer. Further, from the viewpoint of suppressing thermal deterioration, the drying temperature is preferably 120 ° C. or less.

The resin temperature in the extruder is 70 to 17
Preferably it is 0 ° C. If the resin temperature is lower than 70 ° C., the EVOH may not completely melt. Also,
When at least one 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. It is preferably at least 80 ° C, more preferably at least 90 ° C. The resin temperature is 170 ° C
If it exceeds, the EVOH may be susceptible to thermal degradation. Further, when 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 is added as an aqueous solution, when the resin temperature exceeds 170 ° C., evaporation of water becomes severe. Therefore, it may be difficult to mix EVOH and the aqueous solution at a suitable aqueous solution concentration. Preferably 1
It is 50 ° 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.

In the present invention, the resin temperature refers to a temperature detected by a temperature sensor installed in a cylinder of an extruder, and a detected portion indicates a temperature near a discharge port at a tip portion of the extruder.

The present invention relates to a method for removing a saponification catalyst residue contained in the production of EVOH. Specifically, the method is characterized in that an EVOH resin is supplied to an extruder, a cleaning liquid is injected from at least one point of the extruder, the resin is washed, and the cleaning liquid is discharged from at least one point downstream of the injection part. Things.

EVOH to be supplied to an extruder in the present invention
Is preferably an alkali metal ion.

The content of alkali metal ions contained in EVOH supplied to the extruder is preferably in the range of 0.1 to 5% by weight in terms of metal. More preferably, 0.2
% By weight or more, more preferably 0.5% by weight or more. It is more preferably at most 4% by weight, further preferably at most 3% by weight. If it is less than 0.1% by weight, it can be manufactured in a sufficiently space-saving manner by the conventional cleaning method,
The effectiveness of adopting the manufacturing method of the present invention is poor. On the other hand, if it exceeds 5% by weight, L / D
Extruder is required, which is not preferable because the cost is increased.

In the present invention, the alkali metal ion contained in the washed EVOH is preferably 0.05% by weight or less in terms of metal. More preferably 0.04
% By weight, more preferably 0.03% by weight or less. If it exceeds 0.05% by weight, the thermal stability of EVOH deteriorates, which is not preferable.

The washing liquid used in the present invention is not particularly limited as long as it can remove the saponification catalyst residue, but it is an aqueous solution of an acid having a pKa of 3.5 or more at 25 ° C. Is preferred. PKa at 25 ° C
When an aqueous solution of an acid having a pH of less than 3.5 is used, EVOH
May have unsatisfactory coloring resistance and interlayer adhesion. As such an acid having a pKa of 3.5 or more, carboxylic acid is preferable, and acetic acid is particularly preferably used in view of cost and the like. The acetic acid concentration when the acetic acid aqueous solution 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 resin input weight.

The injection of the cleaning liquid is not particularly limited as long as it can inject the cleaning liquid into the extruder, and examples thereof include a method of press-in using a plunger pump or the like. The discharge of the cleaning liquid is not particularly limited as long as it is disposed downstream of the injection section and can discharge the liquid from the extruder, but a dehydration slit or a dehydration hole is preferable. Note that a plurality of injection units or a plurality of discharge units may be arranged.

In the present invention, it is also preferable that after the above-mentioned washing is performed, dehydration or degassing is performed from the hydrous EVOH in the extruder. Specifically, it is preferable to discharge at least one selected from liquid water and steam from at least one location of the extruder. The method of discharging here is not particularly limited, but examples include a method of discharging from a dehydrating slit, a dehydrating hole or a vent provided in a cylinder of the extruder.

Of these, a dewatering slit or a dewatering hole is preferred. Since these can discharge either liquid water or water vapor, it is possible to efficiently remove water from a resin having a high water content, and in this regard, generally only water vapor is discharged. It is often more effective than a vent that cannot. 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.

As the vent port, a vacuum vent for removing steam under reduced pressure or an open vent for removing steam under normal pressure can be used.

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. Suitable examples of such a dewatering slit include a wedge wire type dewatering slit and a screen mesh type 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,
After removing a certain amount of water from the resin having a high water content using a dehydrating slit, it is also possible to further remove water from the vent port downstream of the resin.

The water content of the resin composition comprising EVOH immediately after discharge from the extruder is preferably 5 to 40% by weight,
Particularly preferred is 5 to 35% by weight. When the water content of the resin composition composed of EVOH immediately after discharge from the extruder exceeds 40% by weight, in the resin composition composed of EVOH, the resin and water contained in the resin may easily undergo phase separation, As a result, there is a possibility that the strands discharged from the extruder easily foam. When the water content of the resin composition composed of EVOH immediately after discharge from the extruder is less than 5% by weight, the effect of suppressing deterioration of the EVOH due to heating in the extruder may be insufficient, and the obtained EOH may be insufficient.
The coloring resistance of the VOH pellets may be unsatisfactory.

After washing in an extruder, dehydration or degassing,
At least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt can be added alone, but depending on the embodiment, a carboxylic acid, a boron compound, By adding a plurality of types of compounds selected from a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt in the following suitable ranges, it is possible to improve various performances of the resin composition pellets composed of EVOH. It is.

It is preferable to add a carboxylic acid to the resin composition pellets comprising the EVOH of the present invention from the viewpoint of improving thermal stability. As the carboxylic acid, 25
It is preferred that the pKa at ℃ is 3.5 or more.
When a carboxylic acid having a pKa at 25 ° C. of less than 3.5 is added, it is difficult to control the pH of the resin composition composed of EVOH, which may result in unsatisfactory coloring resistance and interlayer adhesion. Examples of the carboxylic acid include oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, lactic acid, and the like, but acetic acid or lactic acid is preferably used in terms of cost and the like.

The content of the carboxylic acid in the pellets of the dry resin composition comprising the EVOH of the present invention is 10 to 5000 p.
pm. Carboxylic acid content of 10
If it is less than ppm, coloring may occur during melt molding, and if it exceeds 5000 ppm, interlayer adhesion may be insufficient. The lower limit of the content of the carboxylic acid is preferably 30 ppm or more, more preferably 50 ppm.
pm or more. The upper limit of the content of the carboxylic acid is preferably 1000 ppm or less, more preferably 50 ppm or less.
It is 0 ppm or less.

From the viewpoint of improving thermal stability, it is preferable to add a phosphoric acid compound to the resin composition pellets made of EVOH of the present invention. 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. In addition, it is possible to suppress the generation of gel and butter. The above-mentioned improvement effect by the addition of the phosphoric acid compound is particularly remarkable at the time of long run molding using the resin composition pellets made of EVOH and at the time of collecting the molded product. Examples of the phosphate compound include, but are not limited to, 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 lower limit of the content of the phosphoric acid compound is preferably 10 ppm or more, more preferably 30 ppm, in terms of phosphate radical.
pm or more, and the upper limit is preferably 500 ppm or less,
300 ppm or less is more preferable. By containing the phosphoric acid compound in such a range, it is possible to obtain a resin composition pellet made of EVOH, which is less colored and hardly gels. When the content of the phosphoric acid compound is less than 1 ppm, coloring during melt molding may become intense. In particular,
Since the tendency is remarkable when heat histories are repeated, a molded product obtained by molding the resin composition pellets may have poor recoverability. In addition, when the content of the phosphoric acid compound exceeds 1000 ppm, there is a possibility that gels and buttocks of the molded product are easily generated.

The resin composition pellets comprising the EVOH of the present invention can be used from the viewpoints of improving thermal stability and mechanical properties.
It is preferable to include a boron compound (Japanese Patent Publication No. Sho 4
No. 9-20615). When a boron compound is added to a resin composition composed of EVOH, it is considered that a chelate compound is formed between the EVOH and the boron compound. By using such EVOH, improvement in thermal stability compared with ordinary EVOH, mechanical It is possible to improve the properties.

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.

The content of the boron compound in the pellets of the dry resin composition comprising EVOH of the present invention is 20 in terms of boron.
2,000 ppm, preferably 50-100
More preferably, it is 0 ppm. If it is less than 10 ppm, the effect of improving the thermal stability by adding a boron compound may not be obtained, and if it exceeds 2,000 ppm, gelation is likely to occur and moldability may be poor.

By adding an alkali metal salt to the resin composition pellets comprising the EVOH of the present invention,
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 a monovalent metal aliphatic carboxylate, an aromatic carboxylate, a phosphate, and a metal complex. For example, sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate,
And sodium salts of ethylenediaminetetraacetic acid. Among them, sodium acetate, potassium acetate and sodium phosphate are preferred.

It is also preferable to add an alkaline earth metal salt to the resin composition pellets comprising the EVOH of the present invention. When the alkaline earth metal salt is added, the effect of improving the color resistance is slightly reduced, but the amount of the thermally degraded resin adhered to the die of the molding machine during the melt molding using the resin composition pellets is further reduced. It is possible. The alkaline earth metal salt is not particularly limited, but examples thereof include a magnesium salt, a calcium salt, a barium salt, and a beryllium salt, and a magnesium salt and a calcium salt are particularly preferable. Although the anion species of the alkaline earth metal salt is not particularly limited, acetate anions and phosphate anions are preferred.

The content of alkaline earth metal in the pellets of the dried resin composition comprising EVOH of the present invention is 1 in terms of metal.
0 to 1000 ppm is preferred, and more preferably 20 to 1000 ppm.
500 ppm. Alkaline earth metal content of 10
If it is less than ppm, the effect of improving long-run properties may be insufficient, and if it exceeds 1000 ppm, coloring during resin melting may become severe.

The carboxylic acids and boron compounds shown above,
When at least one selected from a phosphate compound, an alkali metal salt and an alkaline earth metal salt is contained in a resin composition pellet made of EVOH, EVOH having an ethylene content of 3 to 70 mol% and a saponification degree of 80 mol% or more is used. Carboxylic acid, boron compound, phosphoric acid compound,
At least one selected from an alkali metal salt and an alkaline earth metal salt can be added. At least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt in an extruder;
By adding a seed, at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is blended with EVOH, and a carboxylic acid, a boron compound,
At least one selected from a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt can be kneaded with very good uniformity. By adopting such a configuration, the motor torque of the extruder during melt molding and its torque fluctuation are small, the extrusion stability, the coloring resistance and the long run property are excellent, and the generation of gel / bubbles and the amount of die attached are small from EVOH. It is possible to obtain resin composition pellets. In the present invention, when adding at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt to an EVOH in an extruder, the extruder such as the carboxylic acid is added to the extruder. The feed position is preferably added at a position where EVOH is melted in the extruder in that the effect of the present invention is sufficiently exhibited. In particular, EVOH in a hydrated and molten state
It is preferable to add the above-mentioned additives.

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 homogeneously compounded.

As the metal salts other than the above-mentioned alkali metal salts and alkaline earth metal salts, metal salts described in the fourth period of the periodic table can be used.

The form of addition of at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts 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. From the viewpoint of controlling the amount of addition and uniformly dispersing at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts in EVOH, a carboxylic acid, a boron compound, A method in which at least one selected from a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is dissolved in a solvent and added as a solution is particularly preferable. Such a solvent is not particularly limited, but at least one kind of solubility selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt, cost advantages, ease of handling, and work environment. From the viewpoint of safety and the like, water is preferred.

The method of adding at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts to EVOH is not particularly limited. It is preferable to add at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts to the extruder from one or more places.

When 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 is added to EVOH as a solution, the amount of EVOH is preferably 100 parts by weight based on the dry weight of EVOH. hand,
The lower limit of the amount of the solution added is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and particularly preferably 5 parts by weight or more. The upper limit of the amount of the solution is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and more preferably 20 parts by weight or less based on 100 parts by weight of the dry weight of EVOH. Particularly preferred. When the addition amount of the solution is less than 1 part by weight, the concentration of the solution generally increases, so that at least one addition selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt is performed. The effect of improving the dispersibility may be reduced. If the amount exceeds 50 parts by weight, it may be difficult to control the water content of the EVOH, and the resin and the water contained in the resin may easily undergo phase separation in the resin composition comprising the EVOH in the extruder. There is.

In the conventional treatment method in which EVOH is impregnated with a solution of an acidic substance and / or a metal salt, it is difficult to obtain a good-quality product of the crumb-like precipitate of EVOH as described above. According to the present invention, it is possible to uniformly add at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt even in such a form of EVOH, and to obtain a stable quality. It is possible to obtain a resin composition pellet made of EVOH.

The method of pelletizing the resin composition comprising EVOH discharged from the extruder is not particularly limited,
An example is a method in which the resin composition is extruded from a die into a strand in a coagulation bath and cut into an appropriate length. From the viewpoint of easy handling of the pellet, the diameter of the die is preferably 2 to 5 mmφ (φ is the diameter; the same applies hereinafter), and the strand is preferably cut to a length of about 1 to 5 mm.

The obtained pellets are usually subjected to a drying step. The moisture content of the resin composition pellets made of EVOH after drying is 1% by weight or less, preferably 0.5% by weight or less. The drying method is not particularly limited, but a stationary drying method, a fluidized drying method and the like are mentioned as preferable examples,
It is also possible to employ a multi-stage drying process in which several drying methods are combined. 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 a conventional treatment method in which EVOH pellets are immersed in a treatment solution containing an acidic substance and / or a metal salt, the water content of the EVOH after the treatment is usually about 40 to 70% by weight. However, the EVOH of the present invention is melted in an extruder, washed in the extruder, dehydrated or degassed, and then at least one selected from a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt. In the case of the treatment method in which one kind is added, the water content of the EVOH resin composition immediately after the extruder is discharged can be arbitrarily adjusted, and the water content immediately after the extruder is discharged is preferably 5 to 4 times.
0% by weight. Therefore, it is possible to obtain pellets having a smaller moisture content than the conventional method. Such pellets having a small moisture content are preferable 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 viewpoint, EVOH pellets having a low moisture content as described above can be obtained.
Is melted in an extruder, washed in the extruder, dehydrated or degassed, and then the present invention comprises adding at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts. Is preferred.

It is also possible to blend EVOH with different degrees of polymerization, ethylene content and saponification degree into resin composition pellets made of EVOH obtained by the above method and melt-mold. Further, other various plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers in the resin composition pellets,
It is also possible to add an appropriate amount of an antistatic agent, a drying agent, a crosslinking agent, a metal salt, a filler, a reinforcing agent such as various fibers, and the like. The resin composition pellets comprising the EVOH of the present invention have a small motor torque of an extruder and a small fluctuation in the torque, and are excellent in extrusion stability. Therefore, depending on the embodiment, the amount of the lubricant used can be significantly reduced, or the lubricant can be used. It is particularly preferred in that it can not be used. However, the use of a lubricant when molding a molded article using the pellets is optional,
Not restricted.

It is also possible to add a suitable amount of a thermoplastic resin other than EVOH as long as the object of the present invention is not impaired. As the thermoplastic resin, various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-
Methyl-1-pentene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin having 4 or more carbon atoms, copolymer of polyolefin and maleic anhydride,
Ethylene-vinyl ester copolymers, ethylene-acrylate ester copolymers, or modified polyolefins obtained by graft-modifying these with unsaturated carboxylic acids or derivatives thereof, and various nylons (nylon-6, nylon-
6,6, nylon-6 / 6,6 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin.

The obtained resin composition pellets comprising the EVOH of the present invention are formed into various molded products such as films, sheets, containers, pipes, fibers and the like by melt molding. These molded products can be crushed and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers and the like. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding. The melting temperature varies depending on the melting point of the copolymer and the like, but is preferably about 150 to 270 ° C.

The resin composition pellets comprising the EVOH of the present invention may be formed by molding at least a molded product such as a film or sheet of the composition of the present invention, in addition to the production of a resin molded product having only a single layer of the resin composition as described above. It is often used practically as a multilayer structure having one layer. As the layer constitution of the multilayer structure, E represents a resin composition comprising EVOH of the present invention, Ad represents an adhesive resin, and T represents a thermoplastic resin.
E / Ad / T, T / Ad / E / Ad / T, and the like, but are not limited thereto. Each layer may be a single layer or may be a multilayer in some cases.

The thermoplastic resin used includes linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene and propylene-α. -Olefin copolymer (carbon number 4
Α-olefins), polybutene, polypentene and other olefins alone or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, polyamide resins such as nylon-6, nylon-6,6, polystyrene, polyvinyl chloride , Polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, chlorinated polypropylene and the like.
Among them, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

In laminating the EVOH and the thermoplastic resin, an adhesive resin may be used, and in this case, an adhesive resin made of a carboxylic acid-modified polyolefin is preferable. The carboxylic acid-modified polyolefin is a modified olefin polymer containing a carboxyl group obtained by chemically (eg, by addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or an anhydride thereof to an olefin polymer. It is suitable. Here, the olefin polymer refers to polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polypropylene, polyolefin such as boribene, a comonomer (vinyl ester, vinyl ester,
And unsaturated carboxylic acid esters, etc.), for example, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ethyl ester copolymer and the like. Among them, linear low-density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content of 5 to 55% by weight), ethylene-
Ethyl acrylate copolymer (content of ethyl acrylate of 8 to 35% by weight) is preferred, and linear low density polyethylene and ethylene-vinyl acetate copolymer are particularly preferred. Ethylenically unsaturated carboxylic acids or anhydrides include ethylenically unsaturated monocarboxylic acids, esters thereof, ethylenically unsaturated dicarboxylic acids, mono or diesters thereof, and anhydrides thereof, and among them, ethylenically unsaturated dicarboxylic acids Anhydrides are preferred. Specific examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate, diethyl maleate, monomethyl fumarate, among others, maleic anhydride Acids are preferred.

The amount of addition or grafting (degree of modification) of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer is 0.01 to 15 with respect to the olefin polymer.
%, Preferably 0.02 to 10% by weight. The addition reaction and graft reaction of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer can be obtained by, for example, a radical polymerization method in the presence of a solvent (such as xylene) and a catalyst (such as peroxide). ASTM-D12 of the carboxylic acid-modified polyolefin thus obtained
The melt index (MI) measured at 190 ° C. by D-1238-65T according to No. 38 is 0.2 to 30 g /
It is preferably 10 minutes, more preferably 0.5 to
10 g / 10 min. These adhesive resins may be used alone or as a mixture of two or more layers.

In the present invention, the above-mentioned multilayer structure can be used as it is in various shapes. However, in order to improve the physical properties of the multilayer structure, it is preferable to carry out a stretching treatment. A stretched film, a stretched sheet, or the like free from stretching unevenness and delamination can be obtained.

The stretching may be either uniaxial stretching or biaxial stretching, and the better the physical properties, the higher the stretching ratio. In the present invention, a stretched film or a stretched sheet free from pinholes, cracks, stretch unevenness, delamination and the like during stretching can be obtained.

Examples of the stretching method include a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, and the like.
Of the deep drawing, vacuum forming and the like, those having a high stretching ratio can be employed. In the case of biaxial stretching, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method can be adopted. Stretching temperature is 80
To 170 ° C, preferably about 100 to 160 ° C.

After completion of the stretching, heat setting is performed. The heat setting can be performed by a well-known means, and heat treatment is performed at 80 to 170 ° C., preferably 100 to 160 ° C. for about 2 to 600 seconds while keeping the stretched film in a tensioned state. The obtained stretched film can be subjected to a cooling treatment, a printing treatment, a dry lamination treatment, a solution or melt coating treatment, a bag making process, a box process, a tube process, a split process, and the like, if necessary.

The shape of the multilayer structure thus obtained may be arbitrary, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and an extruded product having an irregular cross section. In addition, the obtained multilayer structure is required,
Heat treatment, cooling, rolling, printing, dry laminating, solution or melt coating, bag making, deep drawing, box processing, tube processing, split processing, and the like can be performed. The films, sheets, containers and the like obtained as described above are useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

In producing the above-mentioned multilayer structure, another substrate is laminated on one or both sides of a layer of a molded product such as a film or a sheet obtained from the resin composition comprising EVOH of the present invention. However, as a laminating method, for example, a method of melt-extruding a thermoplastic resin on the molded product (film, sheet, etc.), and conversely, a method of laminating the resin composition and another thermoplastic resin on a base material such as a thermoplastic resin. , A method of co-injecting a resin composition comprising a thermoplastic resin and EVOH, and a method wherein a molded product obtained from the resin composition comprising EVOH and a film or sheet of another base material are combined with an organic titanium compound. , Isocyanate compound, a method of laminating using a known adhesive such as a polyester-based compound, and the like. Among them, a method of co-extrusion with another thermoplastic resin is preferable. It is needed. The resin composition comprising the EVOH of the present invention is very excellent in interlayer adhesion, and thus is suitable for a resin composition for coextrusion molding and a coextruded multilayer structure using the same.

The method of coextrusion of the composition of the present invention with a thermoplastic resin may be any of a multi-manifold merging T-die method, a feed block merging T-die method, and an inflation method.

By subjecting the co-extruded multilayer structure thus obtained to secondary processing, various molded products (films, sheets, tubes, bottles, etc.) can be obtained. Can be (1) Multi-layer co-stretched sheet or film by uniaxially or biaxially stretching or biaxially stretching or heat-treating a multi-layered structure (sheet or film) (2) Multi-layered structure (sheet or film) (3) Multi-layered structure (sheet or film, etc.) Multi-layer tray cup-shaped container formed by vacuum forming, air-pressure forming, vacuum-pressure forming, etc. (4) Multi-layered structure Bottles and cup-shaped containers obtained by stretch blow molding from pipes (such as pipes). Such secondary processing methods are not particularly limited, and known secondary processing methods (such as blow molding) other than those described above can also be employed.

The co-extruded multilayer structure and the co-injection multilayer structure thus obtained have less occurrence of gels and butters and have less occurrence of fish eyes and streaks at the time of film formation. For example, it is suitably used as a material for deep drawing containers, cup-shaped containers, bottles and the like.

[0090]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.

(1) Measurement of water content 20 g of water-containing EVOH as a sample was placed in a well-dried weighing bottle, dried at 120 ° C. for 24 hours with a hot-air drier, and the following equation was obtained from the change in EVOH weight before and after drying. 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 Alkali Metal Ions Quantification was performed according to the following method. The “dry pellets” described below means that resin composition pellets made of EVOH are dried at 100 ° C. for 15 hours using a fluidized hot-air dryer, and subsequently dried using a stationary hot-air dryer for 100 hours.
It was obtained by drying at 150C for 15 hours.

10 g of dry pellets as a sample was
The solution was poured into 50 ml of a prescribed 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 alkali metal ions. The column used was ICS-C25 manufactured by Yokogawa Electric Corporation, and the eluent was 5.0 mM tartaric acid and 1.0 mM 2,6.
-An aqueous solution containing pyridinedicarboxylic acid. In the determination, a calibration curve prepared with an aqueous alkali metal chloride solution was used. From the amount of alkali metal ion thus obtained, the amount of alkali metal salt in the dried chip was obtained in terms of metal.

(3) Quantification of added trace components Quantification was performed according to the following method. In addition, the following "dry pellet" refers to E added with at least one selected from carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt in an extruder.
The water content of the resin composition pellets made of VOH was reduced to 0.3% by weight or less by hot air drying. (3-a) Determination of Carboxylic Acid Content 20 g of dry pellets as a sample were put in 100 m of ion exchanged water
and extracted by heating at 95 ° C. for 6 hours. 1 / 50N Na using phenolphthalein as an indicator
Neutralization titration was performed with OH to determine the carboxylic acid content. (3-b) Determination of Alkali Metal and Alkaline Earth Metal Ions 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 metal chloride aqueous solution was used. Thus, the amount of the alkali metal salt and the amount of the alkaline earth metal in the dried pellets were obtained in terms of metal. (3-c) Determination of Boron Compound An aqueous solution of Na ₂ CO ₃ was added to the pellet as a sample, and the pellet was 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 quantified in terms of boron by ICP emission spectroscopy. (3-d) Determination of phosphate ion 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 mM sodium carbonate and 1.0 mM sodium hydrogen carbonate was used. In the determination, a calibration curve prepared with a phosphoric acid aqueous solution was used. From the amount of the phosphate ions thus obtained, the content of the phosphorus compound was obtained in terms of phosphate groups.

(4) 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.

(5) Single-layer film-forming test A single-layer film of an EVOH-containing resin composition was formed using an extruder having the following specifications, and thermal degradation (gel / bushing) of EVOH-containing resin composition pellets and The coloring was examined. The specifications of the extruder are as follows.

Extruder GT-40-A (manufactured by Plastic Engineering Laboratory Co., Ltd.) Model Single screw extruder (non-vented type) L / D 26 CR 3.5 Caliber 40 mmφ Screw Single full flight type, surface nitrided steel Revolution 40 rpm Driving machine Sumitomo Heavy Industries, Ltd. DC motor SCR-DC218B Motor capacity DC7.5KW (Rated 45A) Heater 4-split type Die width 300mm Die resin temperature 240 ° C Picking speed 10m / min. (5-a) Gel / Butt Single-layer film formation of a resin composition composed of EVOH was carried out using dried pellets as a sample, and gel-like bumps of the film 1 hour after the start of film formation (approx. (100 μm or more) were counted and converted to around 1.0 m ² . Judgment was made as follows based on the number of spots. A: Less than 20 B: 20 to 40 C: 40 to 60 D: 60 or more (5-b) Coloring A single-layer film formation of a resin composition composed of EVOH was performed using dried pellets as samples. One hour after the start of film formation, the film was wound around a paper tube, and the degree of coloring of the end face of the film was determined with the naked eye and determined as follows. A: No coloring B: Slightly yellowing C: Yellowing D: Intense coloring

[0097]

EXAMPLE 1 A twin-screw extruder shown in FIG. 1 was used for EVOH having an ethylene content of 32 mol%, a saponification degree of 99.5 mol%, a water content of 40 wt% and a sodium ion content of 1.5 wt% in terms of metal. Supplied. The twin-screw extruder was composed of a raw material supply section, a washing liquid addition section, and a liquid removal section, and a wedge wire type dewatering slit was arranged in the liquid removal section. 0.5 from washing liquid addition part
g / L acetic acid aqueous solution was added. The input amount of EVOH per unit time is 50 kg / hr (including the weight of contained water), and the input amount of acetic acid aqueous solution per unit time is 600 L
/ Hr, and the residence time of the EVOH was 5 minutes. Then, the EVOH discharged from the strand die attached to the tip of the extruder was strand-cut with a pelletizer to obtain pellets. The specifications of the twin screw extruder are shown below. Type Twin screw extruder L / D 42 Caliber 47mmφ Screw Co-rotation complete meshing type Rotation speed 450rpm Cylinder temperature 95 ° C Die temperature 120 ° C Die hole number 5 holes The water content of the resin composition pellets composed of EVOH after discharge from the extruder is 39. % By weight, and the content of sodium ions in the resin was 0.0007% by weight in terms of metal.

[0098]

Examples 2 to 5 Ethylene content of EVOH, degree of saponification,
EVOH pellets were prepared in the same manner as in Example 1 except that the EVOH charging amount, the acetic acid concentration in the washing liquid, and the charging amount under the conditions at the time of extrusion were collectively shown in Table 1. Table 2 shows the obtained evaluation results of detergency.

[0099]

Comparative Example 1 Water-containing EVOH pellets 0.7% of ethylene 32 mol%, saponification degree 99.5 mol%, water content 40% by weight, and sodium ion content 1.5% by weight in terms of metal.
The kg was immersed in 25 L of a 0.5 g / L acetic acid aqueous solution (30 ° C.) and washed for 5 minutes, which is the residence time of the EVOH in the extruder, to obtain washed water-containing EVOH pellets (water content: 40% by weight). And evaluation was performed like Example 1 using the said pellet. Table 2 shows the results.

[0100]

COMPARATIVE EXAMPLE 2 Water-containing EVOH pellets containing 55 mol% of ethylene, a saponification degree of 90.0 mol%, a water content of 43% by weight, and a sodium ion content of 1.0% by weight in terms of metal.
The kg was immersed in 25 L of a 0.5 g / L acetic acid aqueous solution (30 ° C.) and washed for 5 minutes, which is the residence time of the EVOH in the extruder, to obtain washed water-containing EVOH pellets (water content: 43% by weight). And evaluation was performed like Example 1 using the said pellet. Table 2 shows the results.

[0101]

Comparative Example 3 Water-containing EVOH pellets 0.7% of ethylene 10 mol%, degree of saponification 99.0 mol%, water content 45% by weight, and sodium ion content 2.0% by weight in terms of metal.
The kg was immersed in 25 g of an aqueous 0.5 g / L acetic acid solution (30 ° C.) and washed for 5 minutes, which is the residence time of the EVOH in the extruder, to obtain washed hydrous EVOH pellets (water content: 46% by weight). And evaluation was performed like Example 1 using the said pellet. Table 2 shows the results.

[0102]

[Table 1]

[0103]

[Table 2]

The EVOH of the present invention obtained in Examples 1 to 5
The resin composition pellets formed from above were washed and removed of sodium ions that impair long-running properties and appearance, such as inducing thermal degradation, thermal decomposition, and intense coloring during melt molding, depending on the content. In contrast, EVO
In Comparative Examples 1 to 3 using the method of immersing H pellets in washing water and washing in the same time as in Examples 1 to 5, washing and removal of sodium ions were insufficient.

[0105]

Example 6 Ethylene content 32 mol%, saponification degree 9
9.5%, sodium ion content is 1.5 in metal conversion
EVOH having a weight percentage of 52% and a water content of 52% was fed at 10 kg / hr (including the weight of the contained water) to the twin-screw extruder shown in FIG. The twin-screw extruder was composed of a raw material supply section, a cleaning liquid addition section, a liquid removal section, and a trace component addition section, and a wedge wire type dewatering slit was arranged in the liquid removal section. A circular strand die having a diameter of 3 mm and 5 holes was attached to the tip of the extruder. 120 g of 0.5 g / L acetic acid aqueous solution
/ Hr. An aqueous solution composed of acetic acid / boric acid / sodium acetate / magnesium acetate / potassium dihydrogen phosphate shown in Table 4 was added at 0.65 L /
hr. The resin temperature in the strand die was 105 ° C. EV immediately after discharge from the strand die
The OH-containing resin composition was cooled in a water bath, and the solidified strand was cut with a pelletizer to obtain a cylindrical pellet having a diameter of 3 mm and a length of 4 mm. The moisture content of the pellet was 20%. Table 3 shows the conditions at the time of extrusion, Table 4 shows the amount and composition of the additive liquid added per unit time, and the specifications of the twin-screw extruder are shown below.

Model Twin screw extruder L / D 45.5 Caliber 30mmφ Screw Co-rotational complete meshing type Dewatering unit Dewatering slit Rotation speed 300rpm Motor capacity DC22KW Heater 13 division type Number of dice holes 5 holes (3mmφ) Picking speed 5m / min The pellets were dried at 110 ° C. for 12 hours using a hot air drier to reduce the water content to 0.3%. E after drying
The MI of the resin composition pellets composed of VOH is 1.5 g /
It was 10 minutes. Table 5 shows the composition of the dried pellets. Further, the dried pellets were formed into a film by a single screw extruder and evaluated.
It was rank. Table 6 shows the results of the evaluation.

[0107]

Comparative Example 4 As in Comparative Example 1, 32 mol% of ethylene was used.
A water-containing EV having a saponification degree of 99.5 mol%, a water content of 40% by weight, and a sodium ion content of 1.5% by weight in terms of metal.
0.7 kg of OH pellets are added to a 0.5 g / L acetic acid aqueous solution 25
L (30 ° C.) and washed for 5 minutes, which is the residence time of the EVOH in the extruder, to obtain a water-containing EVO.
H pellets (water content 40% by weight) were obtained.

The EVOH pellets were immersed in 10 L of an aqueous solution having the composition shown in Table 4 at 25 ° C. for 6 hours. After immersion, the mixture was centrifugally drained, and the obtained resin composition pellets made of EVOH were dried at 80 ° C. for 3 hours using a fluidized drier to have a water content of 20%. Subsequently, using a hot air dryer,
Film formation was evaluated using dried pellets dried at 12 ° C. for 12 hours to reduce the water content to 0.3%. Table 5 shows the composition of the pellets of the resin composition comprising EVOH and the MI of the pellets, and Table 6 shows the evaluation results.

[0109]

[Table 3]

[0110]

[Table 4]

[0111]

[Table 5]

[0112]

[Table 6]

According to the above embodiment, the coloring resistance is excellent,
An EVOH resin composition pellet having a small amount of gel and bumps and a small amount of die attached can be provided while significantly suppressing thermal deterioration and fusion. In addition, the present invention provides a method for stably depositing a strand, such as a case where EVOH having a low ethylene content and / or a degree of saponification is used, or a case where EVOH is deposited at a high speed to improve production efficiency. In a system in which it was difficult to make EVOH homogeneously contain at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts in the conventional technology, An object of the present invention is to provide a treatment method capable of uniformly containing at least one selected from these additives in EVOH. Furthermore, the present invention can significantly reduce the amount of wastewater in a manufacturing process in which an EVOH contains an acidic substance and / or a metal salt, wastewater treatment equipment in such a step, equipment for re-adding an acidic substance and / or a metal salt, and treatment. A manufacturing method in which equipment for removing impurities in a liquid is omitted can be provided.

[0114]

As described above, according to the method for producing an ethylene-vinyl alcohol copolymer resin of the present invention, the resin is supplied to an extruder, and a cleaning liquid is injected from at least one portion of the extruder. Is washed, and the washing liquid is discharged from at least one place downstream of the washing liquid injection section, so that the saponification catalyst residue can be efficiently removed from the water-containing and molten or semi-molten EVOH with an extruder. Further, the EVOH can be cleaned in a small space. Further, since the EVOH can be washed at a relatively low temperature, deterioration of the polymer can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a schematic process chart of an embodiment showing a cleaning method of the method of the present invention.

FIG. 2 is an explanatory view showing a schematic process chart of one embodiment of adding a trace component after washing in the method of the present invention.

[Explanation of symbols]

1,23 Raw material supply port 2,24 Cleaning liquid addition section 3,25 Drainage section 4,27 Temperature sensor 5a, 5b, 28a, 28b, 28c, 28d Full flight screw section 6,29a, 29b Reverse flight screw section 7,30 Seal ring section 10,20 Twin screw extruder 11,21 Barrel 12,22 Screw 26 Trace component addition section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kawai 1621 Sazu, Kurashiki-shi, Okayama Prefecture Kuraray Co., Ltd. (72) Inventor Masao Hikasa 1621 Sakurazu, Kurashiki-shi, Okayama Prefecture Kuraray F-term (reference) 4F070 AA13 AA26 AB01 AB09 AC11 AC14 AC20 AC43 AE00 AE24 AE30 BA02 BA05 BA10 BB03 BB04 BB05 BB08 DA05 DA50 4F207 AA04 AA10 AA11 AA12 AA15 AA29 AE10 AH54 AH81 AM32 AP05 AR06 KA01 KA17 KA17 K04 KA01 KA17 KA17 K04 KA03 KA17 GA28 HA08 HA09

Claims (14)

[Claims] 1. A method for removing a saponification catalyst residue contained in the production of an ethylene-vinyl alcohol copolymer resin, comprising supplying the resin to an extruder and injecting a washing liquid from at least one portion of the extruder. And washing the resin,
A method for producing an ethylene-vinyl alcohol copolymer resin, wherein the cleaning liquid is discharged from at least one location downstream of the cleaning liquid injection part. 2. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the water content of the ethylene-vinyl alcohol copolymer supplied to the extruder is in the range of 0.5 to 70% by weight. 3. The saponification catalyst residue contained in the ethylene-vinyl alcohol copolymer supplied to the extruder is an alkali metal ion, and the content of the ion is 0.1% in terms of metal.
The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1 or 2, wherein the amount is in the range of 1 to 5% by weight. 4. The ethylene-vinyl according to claim 1, wherein the content of alkali metal ions contained in the washed ethylene-vinyl alcohol copolymer is 0.05% by weight or less in terms of metal. A method for producing an alcohol copolymer resin. 5. The cleaning solution has a pKa at 25 ° C. of 3.
The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of claims 1 to 4, which is an aqueous solution of five or more acids. 6. The ethylene-vinyl alcohol copolymer according to claim 1, wherein the ethylene content is in the range of 3 to 70 mol%.
6. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of items 1 to 5. 7. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the degree of saponification of the ethylene-vinyl alcohol copolymer is in the range of 80 mol% to 100 mol%. . 8. The method according to claim 1, wherein the discharging of the cleaning liquid is at least one means selected from a dewatering slit and a dewatering hole.
7. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of items 7 to 7. 9. The resin melting temperature in the extruder is 70 to 170.
The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of claims 1 to 8, which is in the range of ° C. 10. The method according to claim 1, wherein after the washing liquid is discharged, dehydration or degassing is further performed, and the water content is adjusted so that the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of the above. 11. The ethylene-vinyl according to claim 10, wherein 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 to the resin in the extruder. A method for producing an alcohol copolymer resin. 12. An ethylene-vinyl alcohol copolymer resin containing a saponification catalyst residue is supplied to an extruder, a washing liquid is injected from at least one portion of the extruder, the resin is washed, and an injection section of the washing liquid is provided. A method for producing ethylene-vinyl alcohol copolymer resin pellets, comprising discharging a cleaning liquid from at least one portion downstream of the extruder, and thereafter discharging and cutting the cleaning liquid from an extruder. 13. After draining the washing liquid, dehydration or degassing is performed, and the water content of the resin immediately after being discharged from the extruder is 5 to 5.
The moisture content was adjusted to be 40% by weight, and the carboxylic acid, boron compound, phosphoric acid compound,
The ethylene- according to claim 12, wherein after adding at least one additive selected from an alkali metal salt and an alkaline earth metal salt, the resin composition is discharged from an extruder and cut.
A method for producing a vinyl alcohol copolymer resin pellet. 14. The method according to claim 12, wherein after the resin composition is cut, the resin composition is dried until the water content becomes 1% by weight or less.
3. The method for producing an ethylene-vinyl alcohol copolymer resin pellet according to item 3.