JP2002284887A - Manufacturing method of ethylene/vinyl alcohol copolymer resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a method for adding an inorganic substance to an ethylene/vinyl alcohol copolymer (EVOH) in an extruder thereby to attain better dispersibility of the inorganic substance while suppressing heat deterioration of the EVOH. SOLUTION: An EVOH having a water content of at least 0.5 wt.% is introduced into an extruder. In the extruder, the EVOH containing water and in a molten state is compounded with an aqueous dispersion of an inorganic fine particle, and molten and kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ethylene-vinyl alcohol copolymer (hereinafter abbreviated as "EVOH").
The present invention relates to a method for producing a resin composition.

[0002]

2. Description of the Related Art EVOH has a gas barrier property, oil resistance,
Excellent in fragrance retention and transparency. By utilizing this property, EVOH is formed into films, sheets, bottles, and the like, and is used for food packaging and the like.

Conventionally, if an inorganic substance is added, EVOH
It is known that various characteristics can be improved. For example,
In JP-A-5-39392, a water-swellable phyllosilicate is added in order to improve the gas barrier property of EVOH. Specifically, the publication discloses that EVOH is dissolved in an aqueous dispersion of the silicate (eg, montmorillonite) by adding methanol together with EVOH, and the solution is cooled, solidified, pulverized, and further dried. A method is described. The volatilization of methanol poses a problem in the working environment.

[0004] For example, in Japanese Patent Application Laid-Open No. 2000-43038, an oxide such as silicon oxide is added to improve slipperiness when EVOH is melt-molded. This publication discloses a method for producing an EVOH resin composition in which oxide fine particles are added to an EVOH solution and then precipitated in a coagulation liquid. Here, too, the volatilization of alcohol in the precipitation step causes problems in the working environment.

[0005] JP-A-10-158412 also discloses E
It has been proposed to add a clay mineral such as montmorillonite to a vinyl alcohol copolymer such as VOH.
The publication specifically describes a method in which a vinyl alcohol copolymer to which a clay mineral in a dry state is added is melted and kneaded in an extruder, and then water is further added. In this method, it is necessary to melt and knead the vinyl alcohol copolymer at a high temperature.
OH is heated up to 220 ° C.), and in particular, when EVOH is used, coloring due to thermal deterioration becomes a problem.

[0006] JP-A-2000-191874 discloses that
A method has been proposed in which a water-swellable layered inorganic compound such as montmorillonite and EVOH having a water content of 25 to 50% by weight are melt-mixed in an extruder. In this method,
The inorganic compound is added as a powder. In this method, the temperature for melt-kneading may be low because EVOH in a water-containing state is used. However, it is not easy to sufficiently obtain the dispersibility and cleavage of the inorganic compound only by blending the powder in the extruder and mechanically kneading. Also, EVOH
It is necessary to swell the inorganic compound with the water contained in the EVOH. On the other hand, if the content is too high, it is difficult to form the EVOH. Therefore, it is necessary to control the EVOH water content within a relatively narrow range.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the method of adding an inorganic substance to EVOH in an extruder, and to obtain a better inorganic substance dispersibility while suppressing thermal deterioration of EVOH. I do.

[0008]

Means for Solving the Problems In order to achieve the above object, a method for producing an EVOH resin composition of the present invention comprises introducing an EVOH having a water content of 0.5% by weight or more into an extruder; The method is characterized in that an aqueous dispersion of inorganic fine particles is blended with EVOH in a water-containing and molten state and melt-kneaded.

According to the present invention, EVOH can be melted at a low temperature because it melts in a water-containing state. For this reason, thermal degradation of EVOH can be suppressed. In addition, E which is molten in a water-containing state
When inorganic fine particles are blended as an aqueous dispersion with VOH, the inorganic fine particles can be more uniformly dispersed than when they are blended as a powder. In particular, the dispersibility of water-swelling inorganic substances such as montmorillonite in water promotes cleavage.
The oxygen barrier property of H is improved. Furthermore, when it is blended as an aqueous dispersion, there is obtained an advantage that continuous control of the blending amount is easier than when it is blended as a powder.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In the production method of the present invention, the solid content concentration of the inorganic fine particles in the aqueous dispersion is preferably 0.1 to 50% by weight, more preferably 0.5 to 40% by weight, and particularly preferably 1.0 to 30% by weight. If the concentration is too low, the effect of addition is not sufficiently obtained, and excessive water is added to the system, so that resin is leaked from the dewatering slit or a strand is foamed, which causes poor extrusion. Becomes Conversely, if it is too high, the dispersibility is reduced due to the re-aggregation of the fine particles, which causes poor appearance and reduced oxygen barrier properties.

The amount of the inorganic fine particles varies depending on the type of the inorganic fine particles, but generally, the amount of the inorganic fine particles is preferably 0.001 to 50 parts by weight based on 100 parts by weight of the EVOH. If the compounding amount is too low, the effect of the compounding is difficult to be obtained, while if it is too high, melt molding may be hindered. From such a viewpoint, the amount of the inorganic fine particles to be added is 0.1.
005 to 30 parts by weight, particularly 0.01 to 10 parts by weight, is suitable.

The type of the inorganic fine particles is not particularly limited as long as they can be dispersed in water. For example, glass fillers such as glass fibers, glass flakes and glass beads, zeolite, calcium carbonate, alumina, titanium oxide, silicon dioxide, titanium dioxide Potassium acid, wollastonite, zinc oxide,
At least one selected from barium sulfate, carbon fiber, and an inorganic layered compound can be exemplified.

When the barrier property of EVOH is to be improved, an inorganic layer compound is preferably used. Here, the inorganic layered compound is a structure in which atoms are strongly bonded by covalent bonds or the like to form a densely arranged sheet, and these sheets are stacked almost in parallel by van der Waals force, electrostatic force or the like. And examples thereof include talc, mica, kaolinite, montmorillonite, and vermiculite. The inorganic layered compound may be a natural product or a synthetic product.

As the inorganic layered compound, a swellable inorganic compound which swells or cleaves when immersed in water is preferable, and vermiculite, montmorillonite, synthetic swellable fluorine mica in which lithium, sodium and the like are intercalated between layers are preferable. It is. In particular, montmorillonite and synthetic swellable fluorine mica are excellent in cleavage properties and operability. Here, swelling means that when immersed in a large excess of water, the gap between layers measured by the X-ray diffraction method is widened. Cleavage refers to the gap between layers when the same operation is performed. Indicates that the peaks exhibit such a behavior that they become smaller or disappear.

The weight average aspect ratio (α) of the inorganic layered compound is preferably 3 or more, more preferably 5 or more, and particularly preferably 10 or more. If the aspect ratio is less than 3, the effect of imparting oxygen barrier properties may not be sufficiently obtained. Here, the weight average aspect ratio (α) of the inorganic layered compound is a value calculated from the weight average flake diameter 1 and the weight average flake thickness d using the formula (1).

Α = 1 / d (1)

The weight average flake diameter l of the inorganic filler in the formula (1) is determined by classifying the powder with a micro sieve or sieve having various openings, and determining the result by Rosin-Ramm.
plotted in lar diagram, a value corresponding to the mesh l ₅₀ of micro-sieve or sieve 50 wt% of the total weight of the powder was subjected to the measurement is passed. That is, the weight average flake diameter l of the powder is defined by the formula (2) or (3).

L = l ₅₀ (in the case of micro sieve) (2) l = 2 ^0.5 × l ₅₀ (in the case of sieve) (3)

Of the powder, a portion having a large particle size may be classified with a sieve, and a portion having a small particle size may be classified with a microsieve.

On the other hand, the weight average flake thickness d of the inorganic filler refers to C.I. E. FIG. Capes et al. Reported a single-particle water surface membrane method {C. E. FIG. Capes and R.A. C. Cole
man. Ind. Eng. Chem. Fundam. ,
Vol. 12, No. 2, P. 124-126 (197
3) The occupied area S of the flake on the water surface measured by｝
Is a value calculated from the following equation (4) using

D = W / {ρ (1-ε) · S} (4)

Here, W is the weight of the powder used for measurement, ρ
Is the specific gravity of the powder, and (1-ε) is the occupancy when the powder is in the closest packed state on the water surface.

The method of the present invention is particularly suitable for blending an inorganic layered compound having such a high weight average aspect ratio (α). As described above, water-swellable inorganic substances such as montmorillonite promote cleavage when dispersed in water. Therefore, when added as a water dispersion, the oxygen barrier properties of EVOH are improved.

Weight average flake diameter l of inorganic layered compound
Is preferably 10 μm or less, more preferably 8 μm or less, particularly preferably 6 μm or less. If the weight average flake diameter l exceeds 10 μm, the dispersion stability in the aqueous dispersion may deteriorate, and the transparency of the molded article may deteriorate.

When an inorganic layered compound is used, the compounding amount thereof is preferably 0.1 to 10 parts by weight based on 100 parts by weight of EVOH. If the amount is less than 0.1 part by weight, the effect of improving the barrier property cannot be sufficiently obtained. It is.

When the EVOH film or sheet is wound up or overlaid, the surfaces may adhere to each other (block), causing wrinkles or the like. In such a case, it is preferable to add silicon oxide particles as an antiblocking agent to improve the slip property of the molded article.

As the silicon oxide particles, synthetic silica particles, in particular, porous synthetic silica in which a three-dimensional network structure of Si—O bonds is formed by gelation of silicic acid are preferable. The average particle size of the silicon oxide particles is 10 μm or less,
μm or less, particularly 3 μm or less is suitable. When the average particle size exceeds 10 μm, the dispersion stability in the aqueous dispersion is deteriorated, and the transparency of the molded article may be deteriorated.

When silicon oxide particles are used, the amount thereof is 0.01 to 10 parts by weight based on 100 parts by weight of the EVOH resin.
Parts by weight are preferred. If the amount is less than 0.01 part by weight, the effect of improving the slip property may not be sufficiently obtained. If the amount exceeds 10 parts by weight, aggregation of the silicon oxide particles occurs and the transparency of the molded body is liable to deteriorate.

As described above, as the inorganic fine particles, an inorganic layered compound and / or silicon oxide particles are suitable. However, the other inorganic fine particles exemplified above may be used alone or selected from the inorganic layered compound and silicon oxide particles. It may be used together with at least one of them.

Hereinafter, referring to FIG. 1, EVO in the extruder will be described.
The melting and kneading of H will be described more specifically.
FIG. 1 shows a cylinder of a twin-screw extruder and a screw arranged inside thereof in order to facilitate description of an embodiment of the present invention. First, a hydrous EVOH is supplied from the raw material supply unit 1 of the twin-screw extruder. The EVOH that has been heated or melted to a molten or semi-molten state in the water-containing state is forward (rightward in the figure) by the full flight screw portion 7a.
And the excess water is squeezed out in the liquid removing section 2.
Next, the EVOH is mixed in the reverse flight screw section 8a and then sent to the full flight screw section 7b, where steam is released from the vent port 3 to further adjust the water content of the resin.

Subsequently, the EVOH is sent to the reverse flight screw section 8b and the additives (for example, carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt and alkaline earth metal salt) supplied from the minor component addition section 4 are supplied. And at least one member selected from the group consisting of: Although drained, the EVOH kneaded with the additive is still in a water-containing state.

Furthermore, EVOH in a water-containing and molten state
Is sent to the reverse flight screw section 8c via the full flight screw section 7c, and is melt-kneaded with inorganic fine particles supplied as a water dispersion from the inorganic fine particle addition section 5. In addition, the temperature of the resin is controlled based on the temperature measured by the temperature sensor 6 disposed in the final full flight screw portion 7d in the subsequent stage.

The inorganic fine particles are preferably added to EVOH after washing in an extruder as required. When the inorganic fine particles are added after other additives such as carboxylic acid, the amount of the additive can be easily controlled. When the inorganic fine particles trap the additive, if the inorganic fine particles are added first, it may be difficult to control the amount of the additive.

As the EVOH, one obtained by saponifying an ethylene-vinyl ester copolymer may be used. The ethylene content is usually preferably 3 to 70 mol%,
From the viewpoint of obtaining a molded product having excellent gas barrier properties and melt moldability, the ethylene content is preferably 10 to 60 mol%, more preferably 20 to 55 mol%, and particularly preferably 25 to 55 mol%. The saponification degree of the vinyl ester component in EVOH is usually preferably from 80 to 100 mol%, but 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, E having an ethylene content of 3 to 20 mol%
VOH is suitably used as EVOH having water solubility. The aqueous solution containing EVOH has excellent barrier properties and coating film formability, and can be used as a coating material. EVOH having a saponification degree of 80 to 95 mol% is suitably used for improving the melt moldability. This EVOH may be used alone, or may be used as a blend with EVOH having a degree of saponification of more than 99 mol%.

EVO having an ethylene content of 3 to 20 mol%
Regarding both H and EVOH having a saponification degree of 80 to 95 mol%, it is difficult to obtain pellets having a stable shape simply by extruding a methanol solution of EVOH into a coagulation bath in a strand shape. However, if the present invention is applied,
Regarding the EVOH, pellets are produced stably,
In addition, the inorganic fine particles added to the EVOH can be made uniform.

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 and printability may be insufficient. On the other hand, if the saponification degree is less than 80 mol%, sufficient barrier properties, coloring resistance and moisture resistance cannot be obtained.

The water content of EVOH charged into the extruder is
It may be 0.5% by weight or more, but preferably 5% by weight or more, more preferably 7% by weight or more. This is because EVOH can be melted at a temperature lower than the melting point of EVOH in a dry state. Thus, thermal degradation of the EVOH in the extruder can be suppressed.

On the other hand, the water content of EVOH charged into the extruder is 70% by weight or less, more preferably 60% by weight or less, particularly 50% by weight.
% By weight or less is preferred. When the water content exceeds 70% by weight, in the EVOH composition, the resin and water contained in the resin are likely to undergo phase separation. When water causes phase separation, the resin surface becomes wet and friction increases, so bridges easily occur in the extruder hopper,
The productivity of the pellet may be adversely affected.

The method for adjusting the water content of EVOH before putting it into the extruder is not particularly limited. In order to increase the water content, a method of spraying the resin with water, a method of immersing the resin in water, a method of bringing the resin into contact with water vapor, and the like may be employed. On the other hand, to lower the water content,
Various drying methods may be used. For example, a method of drying using a fluidized hot air dryer or a stationary hot air dryer may be used. However, it is preferable to use a fluidized hot air dryer from the viewpoint of reducing drying spots. In order to suppress thermal deterioration, the drying temperature is preferably 120 ° C. or lower.

The shape of the EVOH to be charged into the extruder is not particularly limited. Pellets obtained by cutting strands precipitated in a coagulation bath are suitable, but crumb-like precipitates in which an EVOH paste has been irregularly coagulated may be used. The EVOH paste may be directly charged into the extruder.

The saponification catalyst residue can be removed from the EVOH by washing in the extruder. Specifically, the cleaning liquid is injected from at least one location of the extruder,
Clean the EVOH and remove at least one downstream of the injection section.
The cleaning liquid may be discharged from the location. Conventionally, the resin pellets are put in a washing vessel in a solid state and brought into contact with a washing solution, thereby extracting saponification catalyst residues by relying on diffusion from inside the pellets. However, when washing is performed simultaneously in the extruder, washing can be performed efficiently and in a space-saving manner.

The saponification catalyst residue contained in the EVOH supplied to the extruder is typically an alkali metal ion. When the content of the alkali metal ion is in the range of 0.1 to 5% by weight in terms of metal, a great effect can be obtained by applying the above-described cleaning method in the extruder. When the content is less than 0.1% by weight, there is not much difference from the case where the conventional cleaning method is applied. Conversely, when the content exceeds 5% by weight,
In order to perform sufficient washing, an extruder having a large screw length (L) / screw diameter (D) is required, resulting in an increase in cost. The content is preferably 0.2% by weight or more, particularly 0.5% by weight or more, and more preferably 4% by weight or less, particularly 3% by weight or less.

The alkali metal ion contained in the washed EVOH is preferably 0.05% by weight or less, more preferably 0.04% by weight or less, particularly preferably 0.03% by weight or less in terms of metal. If the alkali ion metal ion remains in excess of 0.05% by weight, the thermal stability of EVOH may decrease.

The washing solution used in this case is not particularly limited as long as it can remove the saponification catalyst residue. For example, water can be used, but an aqueous solution of an acid having a pKa of 3.5 or more at 25 ° C. Is preferred. When an aqueous solution of an acid having a pKa of less than 3.5 is used, the EVOH may not have sufficient coloring resistance and interlayer adhesion in some cases. pKa
As the acid having a value of 3.5 or more, a carboxylic acid, particularly acetic acid or propionic acid, is suitable. The carboxylic acid concentration in the carboxylic acid aqueous solution is preferably from 0.01 to 10 g / L, particularly preferably from 0.1 to 2 g / L. Further, the injection amount of the cleaning liquid is preferably about 0.1 to 100 liters per 1 kg of EVOH.

The method for injecting the cleaning liquid is not particularly limited as long as it can be injected into the extruder. For example, the cleaning liquid may be injected by using a plunger pump or the like. The method for discharging the cleaning liquid is not particularly limited as long as the liquid can be discharged from the extruder on the downstream side of the injection section. For example, a dehydration slit or a dehydration hole may be used. Note that a plurality of injection units and a plurality of discharge units may be arranged.

In the present invention, as described above, EVO
After or without washing with H, the hydrous EVOH may be dehydrated or degassed. Specifically, water (liquid or gas (steam)) may be discharged from at least one portion of the extruder. Although the discharge of water is not particularly limited, for example, it may be performed using a dewatering slit, a dewatering hole or a vent port arranged in a cylinder of the extruder.

However, it is preferable to use a dewatering slit or a dewatering hole for discharging water. This is because any liquid or gas can be discharged, and water can be efficiently removed from a resin having a high water content. In contrast, vent ports (vacuum vents for removing water vapor under reduced pressure and open vents for removing water vapor under normal pressure) can generally only discharge water vapor. It is also necessary to consider the possibility that the resin adhering to the vent port deteriorates and enters the extruder. In addition, since molten resin may protrude from the dehydration hole,
From this viewpoint, a dewatering slit is more preferable. As the dewatering slit, wedge wire type dewatering slit,
Screen mesh type dewatering slits and the like can be mentioned.

The dehydrating means exemplified above may be used alone, but a plurality of the same type may be used, or a combination of different types may be used. For example, if a certain amount of water is removed from a resin having a high water content using a dewatering slit and then water is further removed from a vent port on the downstream side, dehydration can be performed rationally.

After the washing, dehydration, and / or degassing steps are performed as necessary,
Carboxylic acid, boron compound, phosphoric acid compound, an additive selected from alkali metal salts and alkaline earth metal salts,
Needless to say, it may be added alone, but by adding a plurality of types selected according to the embodiment, EVOH
It is better to improve the various performances of.

When a carboxylic acid is added to EVOH, the thermal stability can be improved. Examples of the carboxylic acid include oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, propionic acid, and lactic acid, but acetic acid, propionic acid, or lactic acid is preferable in consideration of cost and the like.

The content of carboxylic acid is determined by drying EVOH
In a resin composition pellet, 10 to 5000 ppm is preferable. If the content of the carboxylic acid is less than 10 ppm, the coloring resistance at the time of melt molding may not be sufficiently obtained, and if it exceeds 5000 ppm, the interlayer adhesion may be insufficient. The lower limit of the carboxylic acid content is preferably at least 30 ppm, more preferably at least 50 ppm. On the other hand, the upper limit of the carboxylic acid content is preferably 1
000 ppm or less, more preferably 500 ppm
It is as follows.

When a phosphoric acid compound is added to EVOH, the thermal stability can be improved. The content of the phosphate compound in the dried EVOH resin composition pellets is 1 to 10 in terms of phosphate group.
00 ppm is preferred. By adding the phosphoric acid compound in an appropriate range, it becomes possible to suppress the coloring of the molded article and the generation of gels and bumps. 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 EVOH resin composition pellets and at the time of collecting the molded product. Examples of the phosphoric acid compound include, but are not limited to, various acids such as phosphoric acid and phosphorous acid and salts thereof. The phosphate may be a first phosphate, a second phosphate, a third phosphate.
The phosphate may be contained in any form, and the cation species is not particularly limited, but is preferably an alkali metal salt or an alkaline earth metal salt. Among them, phosphoric acid 2
Sodium hydrogen phosphate, potassium dihydrogen phosphate, hydrogen phosphate 2
It is preferable to add a phosphate compound as sodium and dipotassium hydrogen phosphate.

The content of the phosphoric acid compound in the pellets of the dried EVOH resin composition was 10 p
pm or more, especially 30 ppm or more, more preferably 500 ppm or less, especially 300 ppm or less. When the phosphoric acid compound is contained in such a range, it is possible to obtain pellets with less coloring and less gelation. If the content of the phosphoric acid compound is less than 1 ppm, the effect of suppressing coloring during melt molding may not be sufficiently obtained. In particular, when the heat history is repeated, the tendency becomes remarkable, so that the molded product obtained by molding the pellet may have poor recoverability. On the other hand, when the content of the phosphoric acid compound exceeds 1000 ppm, gels and bumps of the molded article are easily generated.

When a boron compound is added to EVOH,
The thermal stability and mechanical properties of VOH can be improved. This is considered to be because a chelate compound is generated between the EVOH and the boron compound. Boron compounds include, but are not limited to, boric acids, borate esters, borates, borohydrides, and the like. Examples of the boric acids include orthoboric acid, metaboric acid, tetraboric acid, and the like.Examples of borate esters include triethyl borate, trimethyl borate, and the like.As the borate, alkali metal salts of the above various boric acids. , Alkaline earth metal salts, borax and the like. Among these compounds, orthoboric acid (hereinafter, simply referred to as "boric acid") is preferable.

The content of the boron compound in the pellets of the dried EVOH resin composition is 10 to 2000 pp in terms of boron.
m, more preferably 50 to 1000 ppm. 10pp
If it is less than 2,000 m, the effect of improving the thermal stability by adding a boron compound may not be sufficiently obtained.
If it exceeds pm, gelation is likely to occur and moldability may be poor.

When an alkali metal salt is added to EVOH,
The interlayer adhesion and compatibility can be effectively improved. Dried EVO
The content of the alkali metal salt in the H resin composition pellets,
5 to 5000 ppm in terms of alkali metal element, and 2
0 to 1000 ppm, especially 30 to 750 ppm is preferred. Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal salt include an aliphatic carboxylate, an aromatic carboxylate, a phosphate, and a metal complex. Examples thereof include sodium acetate, potassium acetate, sodium propionate, potassium propionate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, and sodium salt of ethylenediaminetetraacetic acid. Among them, sodium acetate, potassium acetate, sodium propionate, potassium propionate, and sodium phosphate are preferred.

When an alkaline earth metal salt is added to EVOH, the effect of improving the color resistance is slightly reduced, but the amount of the thermally deteriorated resin adhered to the die of the molding machine during the melt molding of the pellets is reduced. Becomes possible. Examples of the alkaline earth metal salt include, but are not particularly limited to, magnesium salt, calcium salt, barium salt, beryllium salt, and the like, and magnesium salt and calcium salt are preferable. The anionic species of the alkaline earth metal salt is not particularly limited, but is preferably an acetate anion, a propionate anion, or a phosphate anion.

The content of the alkaline earth metal salt in the dried EVOH resin composition pellets is 10 to 100 in terms of the same metal.
0 ppm, more preferably 20-500 ppm, is preferred. When the content of the alkaline earth metal is less than 10 ppm, the effect of improving long-run properties may be insufficient,
If it exceeds 0 ppm, coloring at the time of resin melting may not be sufficiently suppressed.

When the above additives such as carboxylic acid are blended in the extruder, these additives can be uniformly kneaded. In this way, the extrusion torque and the torque fluctuation of the extruder during melt molding are small, so that the extrusion stability,
It is possible to obtain EVOH resin composition pellets which are excellent in coloring resistance and long run property, and have little gel / bubble generation and a small amount of die attached. Further, the above additive is EVOH
Is supplied to a position that is wet and in a molten state,
The above effects can be sufficiently obtained. Further, when the additives are supplied to the kneading section of the extruder, the additives are more easily compounded.

The method of adding the above additives such as carboxylic acid 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 the additive in EVOH, a method of adding the additive as a solution in which the additive is dissolved in a solvent is particularly preferable. In this case, the solvent is not particularly limited, but water is preferable in consideration of the solubility of the additive, cost advantages, easy handling, safety of the working environment, and the like. The additives may be added from one place of the extruder, but may be added from two or more places. The method for injecting the solution is not particularly limited as in the case of the cleaning solution. This point is the same for the aqueous dispersion of inorganic fine particles.

When the above additives are added as a solution to EVOH, the lower limit of the amount of the solution to be added is 1 part by weight or more, and 3 parts by weight or more, relative to 100 parts by weight of the dry weight of EVOH.
It is preferably at least 5 parts by weight, particularly preferably at least 5 parts by weight. The upper limit of the amount of the solution to be added is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, particularly preferably 20 parts by weight or less, based on 100 parts by weight of the dry weight of EVOH. When the addition amount of the solution is less than 1 part by weight, generally, the concentration of the solution becomes so high that the effect of improving the dispersibility of the additive may not be sufficiently obtained. On the other hand, when the addition amount of the solution is larger than 50 parts by weight, E
It may be difficult to control the water content of VOH, and the resin and water contained in the resin are likely to undergo phase separation in the extruder.

Conventionally, a treatment method of immersing EVOH in a treatment solution has been known.
It was difficult to obtain good quality products for crumb-like precipitates of OH and the like. However, when compounded in an extruder, it is possible to uniformly add an additive such as a carboxylic acid to EVOH in such a form, and it is possible to obtain EVOH resin composition pellets of stable quality.

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. The resin temperature is preferably 80 ° C. or higher, particularly preferably 90 ° C. or higher. On the other hand, if the resin temperature exceeds 170 ° C., the EVOH is susceptible to thermal degradation. Further, when the resin temperature exceeds 170 ° C., the evaporation of water becomes intense, so that it becomes difficult to mix EVOH with a suitable concentration of the dispersion or aqueous solution. From this viewpoint, the resin temperature is preferably 150 ° C. or lower, more preferably 130 ° C. or lower. How to adjust the resin temperature
Although not particularly limited, a method of appropriately setting the temperature of the cylinder in the extruder is preferable.

The resin temperature may be determined by applying the temperature measured by a temperature sensor installed on the extruder cylinder. The temperature sensor is suitably installed near the extruder tip discharge port.

The water content of the EVOH resin composition immediately after discharge from the extruder is preferably 5 to 40% by weight, particularly preferably 5 to 35% by weight. Immediately after the extruder is discharged, the EVOH resin composition has a water content of 4
If it exceeds 0% by weight, phase separation between the resin and water contained in the resin is likely to occur. When phase separation occurs, the strand after discharge from the extruder tends to foam. On the other hand, if the water content of the EVOH composition immediately after discharge from the extruder is less than 5% by weight, the effect of suppressing the deterioration of EVOH due to heating in the extruder becomes insufficient, and the coloring resistance of the EVOH pellets becomes insufficient. May not be obtained. Moisture content is adjusted by supplying water to the extruder, removing water from the extruder, or combining water supply to the extruder with removal of water from the extruder. Since water is supplied to the extruder also as a washing liquid, an aqueous dispersion, an aqueous solution, or the like, it is preferable to adjust the supply amount and discharge amount of water in consideration of these.

The method of pelletizing the EVOH resin composition discharged from the extruder is not particularly limited, but the resin composition may be extruded from a die into a strand in a coagulation bath and cut into an appropriate length. In order to facilitate the handling of the pellets, the diameter of the die is preferably 2 to 5 mmφ (φ is the diameter; the same applies hereinafter), and the strand is 1 to 5 mm.
It is good to cut in length.

The obtained pellet is usually subjected to a drying step. The moisture content of the dried EVOH resin composition pellets is preferably 1% by weight or less, more preferably 0.5% by weight. The drying method is not particularly limited, but the stationary drying method,
A fluidized drying method or the like is preferable, and a multi-stage drying step combining some drying methods may be applied. Among them,
First, a method of drying by a fluidized drying method and subsequently drying by a static drying method is preferable.

When the EVOH resin composition pellets are simply immersed in the treatment solution for treatment, the water content of the EVOH after treatment is as follows:
Usually, it reaches about 40 to 70% by weight. However, as in the present invention, when EVOH is melted by an extruder and a necessary treating agent is added in the extruder, the water content of the EVOH resin composition immediately after the extruder is discharged can be easily adjusted.
The water content in the EVOH resin composition is preferably 5 to 5.
40% by weight. By using such pellets having a small water content, energy consumption in the drying step can be reduced.

Pellets having a water content exceeding 40% by weight are:
When the drying temperature is set to 100 ° C. or higher, fusion between the pellets may occur. Also in this respect, the compounding of the additives in the extruder is advantageous.

The EVOH resin composition pellets obtained by the above method may be blended with EVOH having different degrees of polymerization, ethylene content and saponification degree, followed by melt molding. In addition, other various plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, metal salts, fillers, reinforcing agents for various fibers, etc. are added to the pellets in appropriate amounts. It is also possible to add.

It is also possible to blend a thermoplastic resin other than EVOH. 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, polyolefin Copolymer of ethylene and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylate ester copolymer, or modified polyolefin obtained by graft-modifying these with unsaturated carboxylic acid or a derivative thereof), various nylons (nylons) -6,
Nylon-6,6, nylon-6 / 6,6 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, modified polyvinyl alcohol resin, and the like.

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

The above EVOH resin composition pellets may be formed into a film, a sheet, or the like, and put to practical use as a multilayer structure with other layers. The multilayer structure is not particularly limited. When the EVOH resin composition is represented by E, the adhesive resin is represented by Ad, and the thermoplastic resin is represented by T, E / Ad / T,
T / Ad / E / Ad / T and the like. Each layer may be a single layer or a multilayer.

The multilayer structure may be formed into various shapes as it is, but may be subjected to a stretching treatment to improve physical properties. When stretch processing is performed, breakage, pinhole,
A stretched film, a stretched sheet, or the like in which stretching unevenness, delamination, and the like do not occur can be obtained. Stretching may be either uniaxial stretching or biaxial stretching, and in general, the higher the draw ratio, the better the physical properties. As a stretching method, besides a roll stretching method, a tenter stretching method, a tubular stretching method, a stretch blow method, and the like, a deep drawing method, a vacuum forming method, or the like having a high stretching ratio may be employed. In the case of biaxial stretching, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method may be applied. The stretching temperature is, for example, 80 to
The temperature is 170 ° C, preferably 100 to 160 ° C. In the EVOH resin composition in which the inorganic fine particles are uniformly dispersed by applying the present invention, the dispersed inorganic fine particles are oriented by stretching, and the oxygen barrier property is improved. In particular, when biaxial stretching is performed, the oxygen barrier property is significantly improved.

After completion of the stretching, heat setting may be performed.
The heat setting may be performed by a conventional method. For example, the heat setting may be performed while keeping the stretched film under tension.
0 to 170 ° C, preferably 2 to 60 at 100 to 160 ° C
What is necessary is just to process for about 0 second. The obtained stretched film is
If necessary, a cooling process, a printing process, a dry laminating process, a solution or melt coating process, a bag making process, a box process, a tube process, a split process, and the like may be performed.

[0077]

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. 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 equation was obtained from the change in weight of EVOH before and after drying. Was used to determine the water content of EVOH.

Water content (% by weight) = {(weight before drying−weight after drying) / weight before drying} × 100

(2) Quantification of Added Minor Components Quantification was performed according to the following method. In addition, the following “dry chips” refers to E in which 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 in an extruder.
VOH resin composition pellets were obtained by drying at 100 ° C. for 15 hours using a fluidized hot air drier and subsequently drying at 100 ° C. for 15 hours using a stationary hot air drier.

(2-a) Determination of acetic acid content 20 g of a dry chip as a sample was placed in 100 ml of ion-exchanged water.
And extracted by heating at 95 ° C. for 6 hours. 1 / 50N NaO using phenolphthalein as an indicator in the extract
Neutralization titration with H was performed to determine the acetic acid content.

(2-b) Determination of K ion 10 g of a dry chip as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution, and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to quantify the amount of K ions. The column used was "ICS-C25" manufactured by Yokogawa Electric Corporation, and the eluent was 5.0 mM.
Of tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid. In the determination, a calibration curve prepared with an aqueous potassium chloride solution was used. From the amount of K ions thus obtained, the amount of alkali metal salt in the dried chip was obtained in terms of metal.

(2-c) Determination of Boron Compound An aqueous solution of Na ₂ CO ₃ was added to a dry chip to be used as a sample, and ashed 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 chip as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution, and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to determine the amount of phosphate ions. The column used was “ICS-A23” manufactured by Yokogawa Electric Corporation, and the eluent was 2.5
An aqueous solution containing mM sodium carbonate and 1.0 mM sodium bicarbonate was used. In the determination, a calibration curve prepared with a phosphoric acid aqueous solution was used. From the amount of the phosphate ions thus obtained, the content of the phosphate compound was obtained in terms of phosphate groups.

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

(4) Single-layer film forming test (4-a) Film appearance Single-layer film formation of EVOH dried pellets was performed using an extruder having the following specifications, and the film appearance was evaluated. In the evaluation, the appearance of the film one hour after the start of film formation was visually determined.

(Specifications of Extruder) 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-flight full flight type Surface nitrided steel Rotation speed 40 rpm Driving machine DC motor SCR-DC218B manufactured by Sumitomo Heavy Industries, Ltd. Motor capacity DC7.5KW (Rated 45A) Heater 4 division type Die width 300mm Die resin temperature 240 ° C Picking speed 10m / min

(4-b) Coloring The sample (film one hour after the start of film formation) used for evaluating the appearance of the film was wound around a paper tube, and the coloring of the end face of the film was visually determined.

(5) Oxygen permeation amount MODERN CONTROLS INC. JIS K71 under the conditions of 20 ° C. and 65% RH using an oxygen transmission amount measuring device “MOCONOX-TRANS2 / 20 type”.
The measurement was performed according to the method described in No. 26 (isobaric method).

(6) Haze A part of the sample film was cut out, and “HR-100” manufactured by Murakami Color Research Laboratory was used to obtain ASTM D1003-6.
Measured according to 1.

Example 1 Swellable fluoromica having an average particle size of 1 to 5 (μm), an aspect ratio of 20 to 30 and a surface area of 9 (m ² / g) (“Somasif (registered trademark) ME” manufactured by Corp Chemical Co., Ltd.) -100 ") was added to water so as to be 8.0% by weight, and the mixture was stirred using a Henschel mixer for about 15 minutes to prepare an aqueous dispersion of inorganic fine particles (swellable fluoromica).

Ethylene content 44 mol%, saponification degree 9
9.5 mol%, melt index 5 g / 10 when dried
EVOH pellets having a water content of 50% by weight were charged from the raw material supply unit 1 of the twin-screw extruder having the same structure as shown in FIG. Dewatering part (dehydration slit) 2 and vent 3
After collecting the water discharged from the system, the amount of the discharged liquid is 3.
It was 0 L / hour. Further, a treatment liquid composed of an acetic acid / boric acid / potassium dihydrogen phosphate aqueous solution was added from the trace component addition section 4, and a swellable fluoromica aqueous dispersion prepared as described above was added from the inorganic fine particle addition section 5, respectively. .

The amount of EVOH pellets charged per unit time was 10 kg / hour (including the weight of water contained), and the amount of swellable fluoromica aqueous dispersion added per unit time was 1.25 L.
/ H, the amount of the processing solution added from the trace component addition section is 0.25
L / hour. At this time, the composition of the processing solution was 2.2 g of acetic acid.
/ L, boric acid 30g / L, potassium dihydrogen phosphate 0.6
g / L.

The specifications of the twin-screw extruder are shown below (the configuration is the same as in FIG. 1). Type Twin screw extruder L / D 45.5 Diameter 30mmφ Screw Full-meshing direction in the same direction Rotation speed 300rpm Motor capacity DC22KW Heater 13 division type Number of dice holes 5 holes (3mmφ) Resin temperature in extruder 100 ° C Take-off speed 5m / min

The temperature of the resin in the extruder was 100 ° C.
The water content of the EVOH resin composition pellets after the extruder was discharged was 33% by weight. The obtained pellets were dried at 100 ° C. for 25 hours using a fluidized drier, and subsequently dried at 100 ° C. for 15 hours using a stationary drier. As a result, the water content was 0.3% by weight. In the dried EVOH resin composition pellets, the acetic acid content was 100 ppm, the boron compound content was 270 ppm in terms of boron, the phosphate compound content was 20 ppm in terms of phosphate, and the alkali metal salt content was potassium. It was 6 ppm in terms of metal. The melt index was 1.5 g / 10 minutes.

Using the obtained dried pellets, a single layer film of EVOH was formed, and the appearance and coloring of the formed film were evaluated.
As a result of observing the film surface of the film-formed product, no aggregates due to the inorganic fine particles were observed, and there was no coloring due to thermal deterioration of the EVOH, and the appearance was extremely good. The oxygen permeability of this film is 0.6 (cc / m ² · day · atm),
The barrier property was improved about 2.5 times as compared with EVOH containing no inorganic fine particles. The haze of the film is 1.7%, and EVOH containing no inorganic fine particles is used.
And showed almost the same good quality.

(Example 2) A resin composition was obtained in the same manner as in Example 1 except that the aqueous dispersion of inorganic fine particles added in the extruder was changed.

Here, the aqueous dispersion of inorganic fine particles used was prepared as follows. As an inorganic layered compound,
Average particle size 100-2000 (nm), aspect ratio 32
Montmorillonite (“Kunipia (registered trademark) F” manufactured by Kunimine Industries Co., Ltd.) having 0 (average) and a surface area of 25 (m ² / g)
And the inorganic fine particles were added to water so as to be 4% by weight, and the mixture was stirred for about 15 minutes using a Henschel mixer.

Using the obtained dried pellets, a single-layer film forming test was performed. As a result, no agglomerates due to inorganic fine particles were observed on the film surface, and there was no coloring due to thermal degradation of EVOH, and the appearance was extremely good. The oxygen permeability of this film is 0.9 (cc / m ² · day · atm), which is about 1.10 compared to EVOH containing no inorganic fine particles.
A seven-fold improvement in barrier properties was observed. The haze of the film was 1.7%, and EV containing no inorganic fine particles was used.
Good quality almost equivalent to OH.

Example 3 A resin composition was obtained in the same manner as in Example 1, except that the aqueous dispersion of inorganic fine particles added in the extruder was changed.

Here, the aqueous dispersion of inorganic fine particles used was prepared as follows. As porous synthetic silica, an average particle size of 1.4 μm (Coulter counter method),
“Sylysia 310” (manufactured by Fuji Silysia Chemical Ltd.) having a surface area of 300 (m ² / g, BET method) was used. Water was added to this synthetic silica so as to be 4% by weight, and the mixture was stirred for 15 minutes using a Henschel mixer.

Using the obtained dried pellets, a single-layer film forming test was performed. As a result, no agglomerates due to inorganic fine particles were observed on the film surface, and there was no coloring due to thermal degradation of EVOH, and the appearance was extremely good. This film was excellent in blocking resistance, and a good winding roll without wrinkles was obtained. On the other hand, the oxygen permeability of the film is 1.5 (c
c / m ² · day · atm), which is equivalent to EVOH containing no inorganic fine particles. The haze is 3.0
%, But at a level that does not cause any particular problem in appearance.

Comparative Example 1 An ethylene content of 44 mol%
EVOH pellets having a saponification degree of 99.5 mol%, a water content of 0.3 wt% and a melt index of 5 g / 10 minutes were charged into the raw material supply section of the same extruder as in Example 1, and the resin temperature in the extruder was set at 250 ° C. A resin composition was obtained in the same manner as in Example 1 except for the above.

The amount of EVOH pellets charged per unit time was 10 kg / hour (including the weight of contained water). A 8.0 wt% aqueous dispersion of "Somasif ME-100" manufactured by Corp Chemical Co., prepared in the same manner as in Example 1, was supplied at a rate of 2.5 L / hour from the inorganic fine particle addition section. Further, a treatment liquid having a composition of acetic acid 2.2 g / L, boric acid 30 g / L, and potassium dihydrogen phosphate 0.6 g / L was added at an addition amount of 0.5 L / hour per unit time.

The resin temperature at the discharge port was 250 ° C., and EVOH after the discharge from the extruder was strongly colored, and sampling could not be performed due to foaming of water.

Comparative Example 2 A 45 wt% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 44 mol% was charged into a saponification reactor, and a sodium hydroxide / methanol solution (80 g / L) was added to the copolymer. Was added so as to be 0.4 equivalent to the vinyl acetate component, and methanol was added to adjust the copolymer concentration to 20% by weight.
The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, the reaction was terminated by neutralization with acetic acid to obtain a methanol solution of EVOH having an ethylene content of 44 mol% and a saponification degree of 99.5 mol%.

The EVOH solution was extruded into water from a metal plate having a circular opening to precipitate strands, and cut to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. The operation of removing the obtained pellet by a centrifugal separator and adding a large amount of water to remove the liquid was repeated.

3.5 kg of the pellets (water content: 55% by weight) thus obtained were mixed with 6 L of an aqueous solution containing 0.1 g / L of acetic acid, 0.04 g / L of potassium dihydrogen phosphate, and 0.7 g / L of boric acid. For 6 hours at 25 ° C. After immersion, the liquid was removed and the obtained EVOH resin composition pellets (water content 55
% By weight) was dried at 80 ° C. for 15 hours using a fluidized drier and subsequently at 100 ° C. for 24 hours using a stationary drier to obtain dried pellets (water content: 0.3%).

The obtained EVOH pellets after drying have a acetic acid content of 100 ppm, a boron compound content of 270 ppm in terms of boron, a phosphoric acid compound content of 20 ppm in terms of phosphate groups, and an alkali metal salt content. The potassium was 10 ppm in terms of metal. The melt index was 1.5 g / 10 minutes.

To 100 parts by weight of the dried EVOH pellets, 2 parts of the swellable fluoromica ("Somasif (registered trademark) ME-100" manufactured by Corp Chemical) used in Example 1 were added.
Parts by weight, and add a tumbler (N
(ISSUI KAKO) for 5 minutes.

The obtained mixture of the EVOH pellets and the swellable fluoromica was charged into the same extruder as in Example 1, the resin temperature in the extruder was set at 250 ° C., and nothing was added from the trace component addition section and the inorganic fine particle addition section. Extrusion tests were carried out in the same manner as in Example 1, except that no addition was made.

The resin temperature at the discharge port was 250 ° C., and the obtained pellets were dried at 100 ° C. for 25 hours using a fluidized drier. As a result, the water content was 0.3% by weight. Using the obtained dried pellets, a single layer film of EVOH was formed, and the appearance and coloring of the formed film were evaluated.

As a result, agglomerates due to inorganic fine particles were observed on the entire surface of the film, and due to thermal degradation of EVOH, yellowing was severe and the appearance was poor. The oxygen permeability of the film was 1.5 (cc / m ² · day · atm), equivalent to that of EVOH containing no inorganic fine particles, and the effect of improving the barrier property by adding inorganic fine particles was not recognized. The haze of the film was 25%.

(Comparative Example 3) An extrusion test was carried out in the same manner as in Comparative Example 2, except that the inorganic fine particles added by the extruder were changed from "ME-100" to "Sylysia 310".

As a result, agglomerates due to inorganic fine particles were observed on the entire surface of the film, and a film having extremely poor appearance was obtained.
Further, the haze was 10%, and the transparency was poor as compared with EVOH containing no inorganic fine particles. The oxygen permeability of the film was 1.5 (cc / m ² · day · atm).

REFERENCE EXAMPLE A 45% by weight methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 44 mol% was charged into a saponification reactor, and a sodium hydroxide / methanol solution (80 g / L) was added to the copolymer. It was added so as to be 0.4 equivalent to the vinyl acetate component, and methanol was added to adjust the copolymer concentration to 20% by weight.
The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. After 4 hours, the reaction was terminated by neutralization with acetic acid to obtain a methanol solution of EVOH having an ethylene content of 44 mol% and a saponification degree of 99.5 mol%.

The EVOH solution was extruded into water from a metal plate having a circular opening to precipitate strands, and cut to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. The operation of removing the obtained pellet by a centrifugal separator, adding a large amount of water, and removing the liquid was repeated.

3.5 kg of the thus obtained EVOH pellets (water content: 55% by weight) were mixed with 0.1 g / L of acetic acid, 0.04 g / L of potassium dihydrogen phosphate, and 0.7 g / L of boric acid.
Was immersed in a 6 L aqueous solution at 25 ° C. for 6 hours. After immersion, the mixture was drained, and the obtained EVOH resin composition pellets (water content: 55% by weight) were dried at 80 ° C. for 15 hours using a fluidized drier, and subsequently dried at 100 ° C. for 24 hours using a stationary drier. Then, dried pellets (water content: 0.3%) were obtained.

The content of acetic acid in the EVOH resin composition pellets after drying is 100 ppm, the content of boron compound is 270 ppm in terms of boron, the content of phosphoric acid compound is 20 ppm in terms of phosphate, and the content of alkali metal salt is The potassium was 10 ppm in terms of metal. The melt index was 1.5 g / 10 minutes.

A single-layer film was formed using only the dried pellets, and the film surface was evaluated. As a result, a good film having good appearance and little coloring was obtained. The oxygen permeability of the film was 1.5 (cc / m ² · day · atm). The haze was 1.7%.

The above results are summarized in Tables 1 to 4.

(Table 1) Extrusion conditions ―――――――――――――――――――――――――――――――― Inorganic fine particles Treatment liquid Resin Water content (%) Compound Dispersion Blending Addition amount Temperature Extrusion Addition amount Amount (L / hr) (° C) Immediately after (wt%) (L / hr) (parts by weight) ―――――――――――― ―――――――――――――――――――――― Example 1 ME-100 (8.0) 1.25 2 0.25 100 50 33 (swellable fluorine mica) Example 2 1.25 1 0.25 100 50 33 (montmorillonite) Example 3 Sylysia 310 (4.0) 1.25 1 0.25 100 50 33 (porous synthetic silica) Comparative Example 1 ME-100 (8.0) 2.5 2 0.5 250 0.3 Vigorous (swellable fluoromica) ) Foaming Comparative Example 2 ME-100 (dry) ― 1 ― 250 0.3 0.3 (swellable fluoromica) Comparative Example 3 Sylysia 310 (dry) ― 1 ― 250 0.3 0.3 (porous synthetic silica) Reference Example ― ― ― ― 250 0.3 0.3 ――――――――― ―――――――――――――――――――――――― ・ The numerical value added to the inorganic fine particle compound name is the solid content concentration (weight%) in the dispersion. The compounding amount is the inorganic compounding amount to 100 parts by weight of EVOH.

(Table 2) Composition of Processing Solution ――――――――――――――――――――――――――― Acetate Boric Acid Phosphate Compound (g / L) (g / L) (g / L) ――――――――――――――――――――――――――――― Example 1 2.2 30 KH ₂ PO ₄ 0.6 Example 2 2.2 30 KH ₂ PO ₄ 0.6 Example 3 2.2 30 KH ₂ PO ₄ 0.6 Comparative Example 1 2.2 30 KH ₂ PO ₄ 0.6 Comparative Example 2 0.1 0.7 KH ₂ PO ₄ 0.04 Comparative Example 3 0.1 0.7 KH ₂ PO ₄ 0.04 Reference Example 0.1 0.7 KH ₂ PO ₄ 0.04 ―――――――――――――――――――――――――――――

(Table 3) Pellet composition of resin composition ―――――――――――――――――――――――――――――― Acetate Boric acid Phosphate compound K (ppm) (ppm) (ppm) (ppm) ―――――――――――――――――――――――――――――― Example 1 100 270 20 6 Example 2 100 270 20 6 Example 3 100 270 20 6 Comparative Example 1 (No sample was obtained due to foaming) Comparative Example 2 100 270 20 10 Comparative Example 3 100 270 20 10 Reference Example 100 270 20 10- ――――――――――――――――――――――――――――――― ・ Boric acid concentration is equivalent to boron ・ Phosphate compound concentration is equivalent to phosphate radical ・Potassium (K) concentration is metal equivalent

(Table 4) Evaluation result (Film formation quality) ―――――――――――――――――――――――――――――― Appearance Coloring Oxygen transmission Degree Haze (cc / m ²・ day ・ atm) (%) ―――――――――――――――――――――――――――――― Good Good 0.6 1.7 Example 2 Good Good 0.9 1.7 Example 3 Good Good 1.5 3 Comparative Example 1 (Sample was not obtained due to foaming) Comparative Example 2 Aggregate Intensely colored 1.5 25 Comparative Example 3 Aggregate Good 1.5 10 Reference Example Good Good 1.5 1.7 ―――――――――――――――――――――――――――――― ・ Appearance and presence or absence of coloring are visually confirmed. "" Means no color is observed

[0126]

As described above in detail, according to the present invention, it is possible to obtain an EVOH resin composition in which the added inorganic substance is made more uniform while suppressing the thermal deterioration of the EVOH. Also, by using various additives together, EVOH
The properties of the resin composition can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a cylinder and a screw of a twin-screw extruder that can be used for implementing one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Material supply part 2 Dewatering part 3 Vent port 4 Trace component addition part 5 Inorganic fine particle (water dispersion) addition part 6 Temperature sensor 7a, 7b, 7c, 7d Full flight screw part 8a, 8b, 8c Reverse flight screw part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C08L 23/08 C08L 23/08 29/04 29/04 A // B29K 29:00 B29K 29:00 (72 ) Inventor Takaharu Kawahara 1-2-1, Kaigan-dori, Okayama-shi, Okayama Prefecture Inside Kuraray Co., Ltd. (72) Inventor Toshio Tsuboi 1-2-1, Kaigan-dori, Okayama-shi, Okayama Prefecture F-term (reference) 4F070 AA13 AA26 AC04 AC13 AC16 AC18 AC20 AC23 AC27 AC28 AC40 AC55 FC05 4F201 AA19 AB16 AB17 AB19 AC01 AC05 AG01 AG07 AR06 AR20 BA01 BC01 BC12 BC33 BC37 BK13 BK36 BK73 BL08 BL43 BN21 4J002 BB221 DA016 DD057 DD067 DE106DE 136 DG 146 DL006 EF007 EY017 FA016 FA046 FA086 FD016 GG02

Claims (11)

[Claims] An ethylene-vinyl alcohol copolymer resin having a water content of 0.5% by weight or more is introduced into an extruder, and the water-containing and molten ethylene-vinyl alcohol copolymer resin is introduced into the extruder. A method for producing an ethylene-vinyl alcohol copolymer resin composition, comprising mixing an aqueous dispersion of inorganic fine particles and kneading the mixture. 2. The ethylene according to claim 1, wherein the solid content of the inorganic fine particles in the aqueous dispersion is 0.1 to 50% by weight.
A method for producing a vinyl alcohol copolymer resin composition. 3. An amount of the inorganic fine particles in the ethylene-vinyl alcohol copolymer resin of 100 parts by weight of 0.003 parts by weight.
The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1 or 2, which is 1 to 50 parts by weight. 4. The inorganic fine particles are at least one selected from inorganic layered compounds and silicon oxide particles.
4. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 3. 5. An ethylene-vinyl alcohol copolymer having an ethylene content of 3-70 mol% and a saponification degree of 80-80.
The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 4, which is 100 mol%. 6. The ethylene-vinyl alcohol copolymer resin according to claim 1, wherein the water content of the ethylene-vinyl alcohol copolymer resin introduced into the extruder is 0.5 to 70% by weight. A method for producing the composition. 7. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the water content of the resin composition immediately after being discharged from the extruder is 5 to 40% by weight. . 8. An extruder containing water, removing water from the extruder, or combining the supply of water to the extruder with the removal of water from the extruder so that the extruder contains water and melts. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 7, wherein the water content of the ethylene-vinyl alcohol copolymer resin in a state is adjusted. 9. A resin having a melting temperature of 70 to 17 in an extruder.
9. The ethylene according to claim 1, which is at 0 ° C.
A method for producing a vinyl alcohol copolymer resin composition. 10. A carboxylic acid, a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt with respect to a water-containing and molten ethylene-vinyl alcohol copolymer resin in an extruder. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 9, wherein the additive is blended and melt-kneaded. 11. An ethylene-vinyl alcohol copolymer resin composition obtained by the method according to claim 1, which is discharged from an extruder and cut into pellets, and has a water content of 1% by weight. % Of an ethylene-vinyl alcohol copolymer resin composition pellet which is dried until the amount thereof becomes not more than 10%.