JP2001096606A - Method for production of ethylene-vinyl alcohol copolymer resin and of pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which water is removed efficiently, and an additive is added efficiently in the same extruder after the adjustment of water in an ethylene-vinyl alcohol copolymer (EVOH) resin by discharging liquid water and/or water vapor from the water-containing EVOH resin at least in one place in the extruder. SOLUTION: Pellets of an EVOH resin are supplied from the supply port 23 of a twin-screw extruder 20, excess water is removed in liquid removing part 24 to adjust the water content of the resin. Next, an additive is supplied from a trace component addition part 25. The temperature of a molten resin in the extruder is kept at 70-170 deg.C, the amount of water in the extruder so that the water content of the resin immediately after being discharged from the extruder is 5-40 wt.%, and the resin is cut after being extruded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for efficiently removing moisture from a water-containing ethylene-vinyl alcohol copolymer (hereinafter also referred to as "EVOH") resin by using an extruder, and to efficiently use an additive. The present invention relates to a method of well adding the resin.

[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, the melting temperature must be 200 ° C. or higher, and unless the thermal stability of the polymer is improved, the polymer will deteriorate at the time of melt molding, causing fish eyes and bumps and deteriorating the quality of the product. Become. Therefore, it is necessary to remove the saponification catalyst residue contained in the resin at the time of production from the polymer or to add a heat stabilizer.

Conventionally, in order to remove saponification catalyst residues contained in resin production from a 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 No. 55-19242).

However, in the above-mentioned conventional method, a large amount of water adheres to the resin, and hot air drying using a dryer is required to remove the water. In this case, the pellets are fused together depending on the drying temperature. There was a problem of doing.

Further, in order to add a heat stabilizer to the polymer, the resin pellets are placed in an acid treatment vessel and brought into contact with an aqueous acid solution in a solid state to impregnate or adsorb the acid inside the resin pellets (Japanese Patent Application Laid-Open (JP-A) no. JP-A-64-66262).

[0006] 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). 64-66262), (4)
After adjusting the water content of the EVOH pellets to 20 to 80% by weight, the EVOH pellets are brought into contact with an aqueous solution of at least one compound selected from the group consisting of boron compounds, acetates and phosphate compounds (WO 99/05213). Etc. are known.

[0007] However, in the addition method (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. 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. However, when the EVOH pellets treated by the method are molded by melt extrusion, the motor torque and torque fluctuation of the extruder become large, so that it is usually necessary to add a lubricant to the resin composition composed of EVOH at the time of extrusion. Was. However, since the resin composition composed of EVOH is suitably used for food packaging and the like, the addition of such a lubricant is not always desirable from a sanitary point of view. Therefore, reduction or elimination of the lubricant has been desired.

[0008] The EVOH pellets treated by the method (3) or (4) are usually obtained by depositing a methanol solution of EVOH after saponification in a coagulation bath comprising a water / methanol mixed solution. Is obtained by cutting However, the ethylene content is 20 mol%
Less than EVOH and / or less than 95% saponification degree
VOH is difficult to precipitate strands in the coagulation bath, and it is difficult to produce pellets stably because cut mistakes and fine powder are liable to occur, and in some cases, strands cannot be precipitated. The paste-like EVOH precipitates as crumbs solidified in an irregular shape. However, when the crumb-like precipitate is treated by the method (3) or (4), it is difficult to uniformly mix the trace components, and a stable quality product cannot be obtained.

On the other hand, even with EVOH having an ethylene content of 20 mol% or more and a saponification degree of 95% or more, if strand deposition is performed at a high speed in order to improve production efficiency, the deposition of the strand is unstable. Therefore, it is difficult to stably produce the pellets, and the processing method (3) or (4) cannot obtain a product of stable quality.

Further, from the viewpoint of the manufacturing process, 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, a treatment bath for immersing the pellets may be used. A treatment tower is required, and the treatment solution used in such a treatment bath or treatment tower is disposable or collected because acidic substances and / or metal salts are consumed after EVOH treatment. Appropriate amounts of acidic substances and / or metal salts need to be re-added.

It is not preferable to dispose of the treatment liquid from the viewpoint of the effect on the environment, and the treatment liquid is usually discarded through a wastewater treatment facility. When the processing solution is collected and reused, equipment for re-adding acidic substances and / or metal salts and impurities such as oligomers in the processing solution are used to supply products of stable quality. Removal equipment was required.

As described above, the conventional method has a problem that a large processing apparatus needs to be installed and a long-time processing is required, and the manufacturing cost is also high.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, an object of the present invention is to provide a method for efficiently removing water from a water-containing ethylene-vinyl alcohol copolymer resin by using an extruder, and an additive. It is an object of the present invention to provide a method for producing an ethylene-vinyl alcohol copolymer resin, which can efficiently add ethylene-vinyl alcohol to the resin.

[0014]

In order to achieve the above object, a method for producing an ethylene-vinyl alcohol copolymer resin according to the present invention comprises dehydrating or dewatering a water-containing ethylene-vinyl alcohol copolymer resin in an extruder. And discharging at least one selected from liquid water and steam from at least one portion of the extruder.

In the method of the present invention, after dehydration or degassing, at least one additive selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is further added in an extruder. Is preferred.

In the method of the present invention, it is preferable that after dewatering or degassing, the resin is extruded out of the extruder to cut the resin.

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

According to the method of the present invention, water can be efficiently removed from a water-containing ethylene-vinyl alcohol copolymer resin using an extruder, and additives can be efficiently added to the resin.

[0019]

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, it is preferable that the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight.

In the present invention, the method of dehydration or degassing is preferably at least one means selected from a dehydration slit and a dehydration hole.

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

In the present invention, the water-containing ethylene-vinyl alcohol copolymer resin is preferably in a molten or semi-molten state.

Next, the present invention will be described with reference to the drawings. FIG.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a schematic process chart of an embodiment of a dehydration / deaeration method of the present invention. A hydrous EVOH is supplied from the raw material supply unit 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 section 4a of the screw 12, and then kneaded by the reverse flight screw section 5,
Excess water is dehydrated or degassed in the dewatering section 2 composed of a dewatering slit or a dewatering hole, and the water content is adjusted. Next, it is sent forward by the full flight screw part 4b, and sent to a discharge part (not shown). Reference numeral 3 denotes 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 an additive is added after the dehydration / deaeration method of the present invention. Raw material supply unit 23 of barrel 21 of twin screw extruder 20
Is supplied with a hydrous EVOH. The hydrous and molten or semi-molten EVOH is sent forward by the full flight screw portion 27a of the screw 22, and excess water is dehydrated or degassed in the liquid removing portion 24 including a dewatering slit or a dewatering hole. Adjusted. Next, it is kneaded by the reverse flight screw part 28a, and is then sent forward by the full flight screw part 27b. Next, the additive is added in the minor component addition section 25, kneaded by the reverse flight screw section 28b, and sent to the discharge section (not shown) by the full flight screw section 27c. 26 is a temperature sensor.

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.

Further, 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, both the EVOH having an ethylene content of 3 to 20 mol% and the EVOH having a saponification degree of 80 to 95 mol% can be used in a conventional manner. It was difficult to extrude and precipitate a methanol solution into a coagulation bath in the form of a strand, it was difficult to produce stable pellets, and it was also difficult to uniformly contain an acidic substance and a metal salt in the pellets. For such EVOH,
The present invention is significant 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 preferable, but other organic solvents (such as dimethyl sulfoxide) which 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 fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) 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 as 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; After the reaction for 1 to 6 hours, the EVOH contains an alkali catalyst, by-product salts, and other impurities. Therefore, it is preferable to remove these by neutralizing and washing as necessary.

The present invention is a method for dehydrating or degassing EVOH in a water-containing state in an extruder, but the shape of the EVOH before being introduced into the extruder is not particularly limited. Pellets obtained by cutting strands precipitated in a coagulation bath are preferably used, and a crumb-like precipitate obtained by directly coagulating EVOH paste solidified 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 at least 0.5% by weight,
%, 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 EVOH
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 detection point indicates a temperature near a discharge port at a tip of the extruder.

The present invention relates to a process for producing EVOH containing water in an extruder.
The present invention relates to a method for dehydrating or degassing from water. Specifically, at least one selected from liquid water and steam is discharged 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 water vapor under reduced pressure or an open vent for removing water vapor at 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 dehydration or degassing in the extruder, at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts can be added alone. Depending on the embodiment, a carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt, by adding a plurality of types of compounds in a suitable range shown below, from the EVOH Various performances of the resin composition pellet can be improved.

It is preferable to add a carboxylic acid to the EVOH resin composition pellets 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 dry resin composition pellets 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.

It is preferable to add a phosphoric acid compound to the resin composition pellets comprising the EVOH of the present invention from the viewpoint of improving thermal stability. The content of the phosphoric acid compound in the dried resin composition pellets composed of EVOH of the present invention is preferably from 1 to 1000 ppm in terms of phosphate groups,
By adding the phosphoric acid compound in an appropriate range, it is possible to suppress the coloring of the molded product and the occurrence of gel and butter. The above improvement effect by the addition of the phosphoric acid compound is E
This is particularly noticeable at the time of long run molding using the resin composition pellets made of VOH 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 viewpoint 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 dry 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, since the additive is easily mixed uniformly.

As a metal salt 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 to 100 parts by weight of dry weight is added. 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 above-described crumb-like precipitate of EVOH. 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 EVOH after treatment is usually about 40 to 70% by weight. However, after melting the EVOH of the present invention in an extruder and dehydrating or degassing in the extruder, 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 used. In the case of the processing method of adding, the EVOH immediately after discharge from the extruder is used.
Can be arbitrarily adjusted, and the water content immediately after discharge from the extruder is preferably 5 to 40% by weight.
It is. 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.
After melting in an extruder and dewatering or degassing in the extruder,
The treatment method of the present invention in which at least one selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is added is preferred.

It is also possible to blend EVOH having different degrees of polymerization, ethylene content and saponification degree into a resin composition pellet made of EVOH obtained by the above method and melt-mold it. 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 mix 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 and fibers 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 can 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.

When laminating the EVOH and the thermoplastic resin, an adhesive resin may be used, and in this case, an adhesive resin composed 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 anhydride thereof 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 for 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 it is better to perform stretching at the highest possible magnification. 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.

The stretching method includes 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 extrudate having a modified 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-injected multilayer structure obtained in this manner have less occurrence of gels and bumps and 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.

[0089]

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 dryer, and the following formula (Equation 1) was obtained from the weight change of EVOH before and after drying. )
Was used to determine the water content of EVOH.

(Equation 1) Moisture content (% by weight) = (weight before drying−weight after drying) / weight before drying × 100 (2) 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. (2-a) Quantification 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. (2-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. (2-c) Determination of Boron Compound An aqueous solution of Na ₂ CO ₃ was added to a 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. (2-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. (3) Melt index (MI) It was measured at a temperature of 190 ° C and a load of 2160 g using a melt indexer according to ASTM-D1238. (4) Single-layer film-forming test A single-layer film of a resin composition composed of EVOH is formed using an extruder having the following specifications, and the thermal degradation (gel / bubbles) and coloring of the resin composition pellet composed of EVOH are examined. Was. 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 40mmφ Screw Single full-flight type, surface nitrided steel Revolution 40rpm Driving machine DC motor SCR-DC218B manufactured by Sumitomo Heavy Industries, Ltd. Motor capacity: 7.5 kW DC (rated 45 A) Heater 4 split type Die width 300 mm Resin temperature in die 240 ° C Picking speed 10 m / min. (4-a) Gel / Butt Single-layer film formation of a resin composition composed of EVOH was carried out using dried pellets as a sample, and the 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 (4-b) Coloring A single layer film formation of a resin composition made 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 (5) Fusing 500 g of a resin composition pellet made of EVOH after discharge from the extruder was gently sieved with a 5-mesh wire mesh. Then, the weight of the fused pellet remaining on the wire net was measured, and the occurrence rate of the fused pellet was expressed in terms of% by weight using the following equation (Equation 2).

(Equation 2) Fusing Occurrence Rate (%) = Fused Pellets Weight (g) × 100/500
(g)

[0093]

Example 1 Ethylene content 32 mol%, saponification degree 9
EVOH having a water content of 9.5% and a moisture content of 52% was charged into the twin-screw extruder shown in FIG. 1 and extruded from a circular strand die having a diameter of 3 mm and 5 holes. The twin-screw extruder was composed of a raw material supply section and a liquid removing section, and a wedge wire type dewatering slit was arranged in the liquid removing section. The resin temperature at the discharge port was 105 ° C.
Further, the EVOH immediately after the discharge was cooled in a water bath, and the solidified strand was cut with a pelletizer into a cylindrical pellet having a diameter of 3 mm and a length of 4 mm.

The input amount of EVOH per unit time is 10
kg / hr (including the weight of water contained), and the amount of dehydration per unit time was 4.00 kg / hr. The conditions at the time of extrusion are shown in Table 1, and the evaluation results are shown in Table 2. The specifications of the twin-screw extruder are shown below.

Type Twin screw extruder L / D 45.5 Caliber 30mmφ Screw Co-rotation complete meshing type Dewatering section Dewatering slit Rotation speed 300rpm Motor capacity DC22KW Heater 13 division type Number of dice holes 5 holes (3mmφ) Picking speed 5m / The water content of the EVOH pellets after discharge from the min extruder was 20%. The fusion ratio of the pellet was 0%.

[0096]

Examples 2 and 3 Except that the ethylene content of EVOH, the degree of saponification, the resin temperature, the water content, and the water content after discharging from the extruder were changed as shown in Table 1 before being charged into the twin-screw extruder. An EVOH pellet was prepared in the same manner as in Example 1.
The fusion evaluation was performed. The conditions at the time of extrusion are shown in Table 1, and the evaluation results are shown in Table 2.

[0097]

Example 4 EVOH pellets were prepared in the same manner as in Example 1 except that the dewatering section was changed from a dewatering slit to an open vent using a twin-screw extruder, and fusion evaluation was performed. The conditions at the time of extrusion are shown in Table 1, and the evaluation results are shown in Table 2.

[0098]

Comparative Example 1 EVOH pellets having ethylene of 32 mol%, a saponification degree of 99.5 mol%, and a water content of 52% were dried at 80 ° C. for 3 hours using a fluidized drier to have a water content of 20%. The fusion rate of the pellets was measured in the same manner as in Example 1. Table 2 shows the evaluation results.

[0099]

Comparative Examples 2 and 3 Fusion evaluation was performed in the same manner as in Comparative Example 1 except that the ethylene content, the degree of saponification, and the water content of the EVOH pellets were changed as shown in Table 1. Table 2 shows the evaluation results.

[0100]

[Table 1]

[0101]

[Table 2]

[0102]

Example 5 Ethylene content 32 mol%, saponification degree 9
9.5%, EVOH with a water content of 52% is 10 kg / hr.
(Including the weight of water contained) and fed to the twin screw extruder shown in FIG. The twin-screw extruder was composed of a raw material supply section, a liquid removing section, and a trace component adding section, and a wedge wire type dewatering slit was arranged in the liquid removing section. 3mm diameter at the extruder tip
Was used to attach a 5-hole circular strand die. An aqueous solution composed of acetic acid / boric acid / sodium acetate / sodium dihydrogen phosphate shown in Table 4 was added at 0.65 L / h from the trace component addition section.
was added at a rate of r. At this time, 4.65 kg from the liquid removal part
/ Hr water was drained. The resin temperature in the strand die was 105 ° C. E immediately after discharge from the strand die
The resin composition comprising VOH was cooled in a water bath, and the solidified strand was cut with a pelletizer to obtain a columnar 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.

Type Twin screw extruder L / D 45.5 Caliber 30mmφ Screw Co-directional complete meshing type Dewatering unit Dewatering slit Rotation speed 300rpm Motor capacity DC22KW Heater 13 division type Number of dice holes 5 holes (3mmφ) Pulling speed 5m / min The fusion rate of the obtained pellets was 0%. Next, the pellet was dried at 110 ° C. for 12 hours using a hot-air drier to reduce the water content to 0.3%. EVOH after drying
MI of the resin composition pellets consisting of 1.5 g / 10 m
was in. 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. As a result, both the gel and the spot and the coloring were ranked A. Table 6 shows the results of the evaluation.

[0104]

Examples 6 and 7 Table 3 shows the ethylene content of EVOH, the degree of saponification, the die temperature, the amount of EVOH charged per unit time, the water content, and the water content after discharge from the extruder before being charged into the twin-screw extruder. Table 4 shows the charged amount and composition per unit time of the additive solution composed of acetic acid / boric acid / sodium acetate or calcium acetate / sodium dihydrogen phosphate or potassium dihydrogen phosphate aqueous solution. Except for the above, pellets of a resin composition composed of EVOH were prepared and evaluated in the same manner as in Example 5. Table 3 shows the conditions at the time of extrusion, and Table 4 shows the composition of the additive liquid.
Table 5 shows the composition of the pellets of the resin composition composed of OH, and Table 6 shows the evaluation results.

[0105]

Example 8 EVOH pellets were prepared in the same manner as in Example 5, except that the dewatering section was changed from a barrel having a dewatering slit to a barrel having a vacuum vent with a twin-screw extruder. Film evaluation was performed. The conditions at the time of extrusion are shown in Table 3, the composition of the treatment liquid is shown in Table 4, the composition of the pellets of the obtained resin composition composed of EVOH is shown in Table 5, and the evaluation results are shown in Table 6.

[0106]

Comparative Example 4 EVOH pellets having 32 mol% of ethylene, a saponification degree of 99.5 mol% and a water content of 52% 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%. The fusion rate of the pellets was measured in the same manner as in Example 5, and the pellets were dried using a hot air dryer at 110 ° C. for 12 hours to reduce the water content to 0.3%. Film evaluation was performed. EVO
Composition of Pellets of Resin Composition Consisting of H and M of Pellets
I is shown in Table 5, and the evaluation results are shown in Table 6.

[0107]

Comparative Examples 5 and 6 The ethylene content, saponification degree and water content of EVOH were changed as shown in Table 3 and acetic acid / boric acid / sodium acetate or calcium acetate / sodium dihydrogen phosphate or soaked EVOH was used. Resin composition pellets composed of EVOH were prepared and evaluated in the same manner as in Comparative Example 4, except that the composition of the treatment solution composed of an aqueous solution of potassium dihydrogen phosphate was changed as shown in Table 4. E obtained
Table 5 shows the composition of the pellets of the resin composition composed of VOH.
Table 6 shows the evaluation results.

[0108]

[Table 3]

[0109]

[Table 4]

[0110]

[Table 5]

[0111]

[Table 6] According to the above embodiment, it is possible to provide an EVOH resin composition pellet having excellent coloring resistance, low generation of gels and bumps, and a small amount of adhered die, 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. Further, the present invention can significantly reduce the amount of wastewater in the production process of adding an acidic substance and / or a metal salt to EVOH,
It is possible to provide a manufacturing method in which wastewater treatment equipment, equipment for re-adding acidic substances and / or metal salts, and equipment for removing impurities in the treatment liquid are omitted in such a step.

[0112]

As described above, the present invention can efficiently remove water by discharging liquid water and / or steam from a water-containing EVOH resin at at least one location in an extruder. Further, the additives can be efficiently added in the same extruder after adjusting the water content of the EVOH resin.

In addition, as compared with the conventional hot air drying method, deterioration and coloring due to heat during drying are small, and fusion between the pellets and between the pellets and the inner wall of the device can be avoided. Furthermore, stable strand deposition is difficult, such as when EVOH having a low ethylene content and / or saponification degree is used, or when EVOH is subjected to high-speed strand deposition to improve production efficiency. As for the system, it is possible to provide a production method which enables uniform drying, whereby a product of good quality can be provided even for EVOH having a low ethylene content and / or low saponification degree, which has conventionally been difficult to produce with stable quality. Can be produced, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic process chart of an embodiment of a dehydration / deaeration method of the present invention.

FIG. 2 is an explanatory view showing a schematic process chart of one embodiment of a method of adding an additive after dehydration and degassing in the method of the present invention.

[Explanation of symbols]

 1,23 Raw material supply port 2,24 Drainage part 3,26 Temperature sensor 4a, 4b, 27a, 27b, 27c Full flight part 5,28a, 28b Reverse flight screw part 25 Trace component addition part

 ──────────────────────────────────────────────────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) 4F207 AA10 AR06 KA01 KA17 KK13 KK54 KL41 KW23

Claims (11)

[Claims] 1. A method for dehydrating or degassing a water-containing ethylene-vinyl alcohol copolymer resin in an extruder, wherein at least one selected from liquid water and steam is discharged from at least one portion of the extruder. A method for producing an ethylene-vinyl alcohol copolymer resin. 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 method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the water content of the resin immediately after being discharged from the extruder is 5 to 40% by weight. 4. The method for producing an ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the method of dehydration or degassing is at least one means selected from a dehydration slit and a dehydration hole. 5. The ethylene-vinyl alcohol copolymer according to claim 1, wherein the ethylene content is in the range of 3 to 70 mol%.
5. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of items 1 to 4. 6. 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%. . 7. 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 6, which is in the range of ° C. 8. After dehydration or degassing, at least one additive selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts is further added in the extruder. The ethylene-biene according to any one of claims 1 to 7, 9. The water-containing ethylene-vinyl alcohol copolymer resin is in a molten or semi-molten state.
9. The method for producing an ethylene-vinyl alcohol copolymer resin according to any one of items 1 to 8. A method for producing a nyl alcohol copolymer resin. 10. The method for producing an ethylene-vinyl alcohol copolymer resin pellet according to claim 1, wherein after dehydration or degassing, the resin is extruded out of the extruder to cut the resin. 11. After the resin is cut, the water content is reduced to 1
The method for producing ethylene-vinyl alcohol copolymer resin pellets according to claim 10, wherein the pellets are dried until the amount becomes less than or equal to% by weight.