JP2002293948A - Method for producing ethylene-vinyl alcohol copolymer resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene-vinyl alcohol copolymer (EV)
OH) in order to respond to the diversification of uses
Provided is a method capable of producing VOH efficiently and stably, and in which components to be blended are uniformly dispersed. The water content extruded from a first extruder is 5%.
At least a part of ４０40% by weight of EVOH (component A) is introduced into a second extruder, and an additional component (component B) is blended and kneaded with component A in a molten state in the second extruder. And then discharge. Further components (component C) may be introduced into the first extruder.

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.

[0003] Conventionally, various components other than EVOH are blended to improve various characteristics of EVOH. It has also been proposed to mix a resin with EVOH in an extruder. For example, JP-A-5-93092 describes a method for improving the dispersibility of starch by mixing starch and EVOH in a molten state. In the embodiment described in the publication, a mixture of starch and glycerin is fed to a twin-screw extruder and supplied to a twin-screw extruder.
℃ and melted through the side feed port of this twin screw extruder,
EVOH heated and melted at 210 ° C. by a single screw extruder is supplied, and both are kneaded in a twin screw extruder.

When dry EVOH is introduced into an extruder, it needs to be melted at a high temperature as described above. In the method disclosed in JP-A-5-9334, EVOH in a water-containing state is used. According to the publication, EVOH pellets having a water content of 20 to 60% by weight and raw starch (corn starch having a water content of 12%) are charged into a Henschel mixer and mixed, and this mixture is supplied to a twin-screw extruder equipped with a vent. And kneading at 120 ° C., melt-extrusion into strands, and pelletizing the strand-like solid using a pelletizer.

It has also been proposed to mix inorganic fine particles with EVOH in an extruder. JP-A-10-1584
No. 12 proposes adding a clay mineral such as montmorillonite to a vinyl alcohol copolymer such as EVOH. 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.

[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.

[0007]

With the diversification of the use of EVOH, the EVOH production line is usually manufactured with a special brand in which necessary additives are further blended as needed without reducing the productivity while producing a brand. It is required to produce brands. As described above, a kneading method in consideration of the characteristics of the components to be blended has been conventionally studied. However, a kneading method suitable for a request for small-quantity multi-product production has not yet been proposed. In the case of producing many kinds, the components to be added are appropriately changed, but a kneading method excellent in versatility capable of uniformly dispersing the components to be mixed in the resin composition is also required.

[0008] Accordingly, the present invention provides an EVOH of a small quantity and a large variety.
It is an object of the present invention to provide a method suitable for producing a resin composition and capable of uniformly dispersing components to be blended.

[0009]

Means for Solving the Problems In order to achieve the above object, a method for producing an EVOH resin composition according to the present invention comprises an EVO having a water content of 5 to 40% by weight extruded from a first extruder.
At least a part of H (component A) is introduced into a second extruder, and an additional component (component B) is mixed and kneaded with component A in a molten state in the second extruder, and then discharged. It is characterized by doing.

[0010] According to the invention, in the first extruder, E
Since the water content of VOH is adjusted to 5 to 40% by weight,
EVOH obtained from the first extruder can be stabilized (for example, strand foaming and frequent occurrence of strand breakage can be suppressed), and raw materials can be smoothly supplied to the second extruder. For this reason, the extrusion stability in the second extruder is improved, and the quality and shape of the pellet obtained from this extruder can be stabilized. In this manner, a series of extrusion steps using the first and second extruders and a subsequent EVOH molded article manufacturing step using pellets can be stabilized, and the quality of the molded article can be improved. According to the present invention using a plurality of extruders, for example, an EVOH containing no component B obtained from the first extruder and an EVOH resin composition containing the component B obtained from the second extruder are stable. Thus, EVOH molded articles of different brands can be efficiently produced using these. According to the present invention, loss at the time of brand switching can be avoided.

Further, according to the present invention, the molten EVO
Since a component for improving properties is mixed with H, higher dispersibility can be easily obtained than in the case where it is mixed with EVOH which is a solid.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. In one embodiment of the present invention, a portion of the EVOH (component A) having a moisture content of 5 to 40% by weight extruded from the first extruder is introduced into the second extruder and melted in the second extruder. By mixing and kneading the component B with the component A in the state and discharging the mixture, the remaining EVOH obtained from the first extruder (without mixing the component B) and the second
And the EVOH resin composition (comprising component B) obtained from the extruder of (1). "Second extruder"
, A plurality of extruders may be prepared, and different components (components B1, B2, B3,...) May be introduced into these extruders, respectively, to produce more types. In this case, all of the EVOH obtained from the first extruder is distributed to the second extruder (s) and the different components B1, B2, B3.
··· may be obtained to obtain a plurality of brands of EVOH resin compositions.

In another embodiment of the present invention, a component other than the components A and B (component C) is introduced into the first extruder. For example, EVOH (component A) and component C are melt-kneaded in a first extruder, extruded from the first extruder so that the water content becomes 5 to 40% by weight, and one of the extruded resin composition is extruded. Part was introduced into the second extruder, and the resin composition in the molten state in the second extruder was mixed with the component B, kneaded, and then discharged, thereby obtaining the resin composition from the first extruder. The remainder of the EVOH resin composition (compounded with component C) and the EVOH resin composition (compounded with component B and component C) obtained from the second extruder can be obtained. Heretofore, the introduction of multiple components in a single extruder has been considered exclusively. However, in order to add various functions to a single extruder, the screw diameter is increased, and the screw length (L) with respect to the screw diameter (D) is increased.
Must also be increased. On the other hand, in the above method, since components are compounded using a plurality of extruders, it is not necessary to excessively increase the L / D,
It is also possible to avoid an increase in the cost of the manufacturing equipment and to expand the range of equipment selection.

In the first extruder, the water content of the resin in the extruder may be adjusted by supplying water, removing water, or combining water supply and water removal. In this case, the water is preferably supplied and removed as a liquid. For example, moisture is also removed as water vapor from a vent provided for adjusting the pressure in the extruder, but in order to efficiently obtain a resin having a water content within a predetermined range, at least dehydration from the dewatering unit is performed. Is preferred. As described later, a cleaning liquid may be introduced into the first extruder. The components may be blended as an aqueous solution. When supplying these washing liquids and aqueous solutions to the extruder, in order to efficiently discharge water contained in each liquid, it is particularly desirable to dispose a liquid removing section. In supplying and / or removing water, the number and order of supply and removal are not limited.

As described above, components other than the components A and B (component C) are introduced into the first extruder as required. Component C is not particularly limited, but is preferably selected from highly versatile additives usually required for brands. Component C comprises a carboxylic acid,
At least one selected from a boron compound, a phosphoric acid compound, an alkali metal salt and an alkaline earth metal salt is preferred. Of course, various resins described below as representative examples of the component B may be used as the component C.

The component B to be introduced into the second extruder is also not particularly limited, and may be appropriately determined according to the presence or absence of the component C and, if so, the type thereof. The above carboxylic acid and the like may be used as the component B.

Examples of the components B and C include various resins and plastic additives such as plasticizers, antioxidants, lubricants, ultraviolet absorbers, antistatic agents, flame retardants, and crystal nucleating agents. Among the plastic additives, an antioxidant is preferable. As the antioxidant, a hydrotalcite-based compound as an inorganic compound, hindered phenol, hindered amine, and a phosphorus-based antioxidant as organic compounds are preferable. Component B and component C do not need to be a single type, and a plurality of types of components may be introduced into each extruder.

The component B may be introduced into an extruder in a solid state such as a powder or as a melt, but is preferably blended as a solute contained in a solution or a dispersoid contained in a dispersion. This is because they can be dispersed more uniformly than when they are blended as a powder or the like. When blended as a fluid such as a solute, there is also obtained an advantage that continuous control of the blended amount becomes easy. As the solution and the dispersion, an aqueous solution and an aqueous dispersion are suitable, respectively.

As the component B, resin and inorganic fine particles are frequently used. Hereinafter, an embodiment in which a resin or inorganic fine particles are blended as an aqueous solution or an aqueous dispersion as the component B will be described.

First, the case where the resin is blended as an aqueous solution or an aqueous dispersion will be described. The concentration of the resin in the aqueous solution of the resin or the aqueous dispersion of the resin (solid concentration in the aqueous dispersion) is preferably 0.5 to 70% by weight. If the concentration of the resin is too low, the compounding efficiency is reduced, while if it is too high, the fluidity of the liquid is reduced and sufficient dispersibility may not be obtained. From this viewpoint, the concentration is more preferably from 1.0 to 65% by weight, particularly preferably from 5.0 to 60% by weight.

The amount of the resin is preferably 0.1 to 200 parts by weight based on 100 parts by weight of EVOH. If the amount is less than 0.1 part by weight, various effects of the blend cannot be sufficiently obtained. Conversely, if the amount is more than 200 parts by weight, E
In some cases, the gas barrier properties of VOH cannot be sufficiently obtained. From this viewpoint, the amount is more preferably from 1.0 to 150 parts by weight, particularly preferably from 5.0 to 100 parts by weight.

As the resin to be mixed as the resin aqueous solution,
There is no particular limitation as long as it is soluble in water. For example, polyvinyl alcohol (hereinafter abbreviated as “PVA”), EV
OH, starch and its derivatives, cellulose derivatives,
Polyacrylic acid and its salts, polyvinylpyrrolidone,
At least one selected from polyoxyethylene glycol and polyoxypropylene glycol is exemplified. Water-soluble polymer compounds such as PVA and starch
By blending with VOH, EVOH can be easily disintegrated in water or biodegradable by microorganisms. PVA
When a water-soluble resin is added as an aqueous solution,
Dispersibility and moldability are improved, and a molded article having good appearance is easily obtained.

PVA is a saponified product of polyvinyl acetate, and preferably has a saponification degree of 80 mol% or more. PVA
Has a melting point and a thermal decomposition temperature close to each other. Therefore, P
When VA is melted and kneaded with EVOH at a temperature not lower than its melting point (230 ° C.), PVA is easily thermally decomposed and foamed. In addition, if EVOH and PVA in a dry state are simply blended in an extruder, the PVA is likely to aggregate and the appearance becomes poor. In this case, the interface between the agglomerated PVA and EVOH becomes brittle, so that fine powder is likely to be generated during transfer or during the pellet drying step. However, EVOH and PV in a hydrated and molten state
If the aqueous solution A is melt-kneaded at a low temperature of, for example, 170 ° C. or lower, the dispersibility of PVA can be improved while suppressing the thermal decomposition or gelation of PVA, so that a good molded body can be obtained.

[0024] Starch tends to decompose at about 200 ° C due to thermal degradation. For this reason, at the normal EVOH melt molding temperature, thermal decomposition occurs and foaming occurs. However, the EVOH and the aqueous starch solution in a water-containing and molten state are mixed with each other, for example, for 1 hour.
Melt kneading at a low temperature of 70 ° C. or less can improve the dispersibility of the starch while suppressing the thermal decomposition of the starch, so that a good molded body can be obtained.

EVOH also has water solubility if the ethylene content is 20 mol% or less and the saponification degree is 80 mol% or more.
When this water-soluble EVOH is melt-kneaded at 200 ° C. or more,
Susceptible to thermal degradation. Also, the dispersibility becomes poor,
The transparency of the molded article is reduced. However, similarly to the above, by melt-kneading with water-containing and molten EVOH, a good molded article can be obtained while suppressing thermal decomposition or gelation of the water-soluble EVOH.

Similarly, water-soluble polymer compounds such as polyoxyethylene glycol and polyoxypropylene glycol can be used as a plasticizer for EVOH.

The resin blended as the resin aqueous dispersion is not particularly limited as long as it can be dispersed in water. The aqueous dispersion may be a suspension (suspension) or an emulsion (emulsion). Also,
A dispersion stabilizer or the like may be added in addition to the resin. It is preferable to mix an emulsion from the viewpoint of dispersion stability. This is because when the dispersion state is stable, the clogging of the inlet to the extruder can be prevented, and it is easy to quantitatively compound the compound. As a resin emulsion,
For example, at least one selected from a polyvinyl acetate emulsion, a polyacrylate emulsion, a polyurethane emulsion, an EVOH emulsion, and a latex may be used.

The polyvinyl acetate emulsion is an emulsion containing at least one selected from a homopolymer of vinyl acetate and a copolymer containing vinyl acetate as a main component. Examples of the copolymer include copolymers with acrylic acid ester, maleic acid, fumaric acid ester, fatty acid vinyl ester, ethylene, and the like. The copolymer with ethylene preferably has an ethylene content of 10 to 30% by weight, and may be a terpolymer containing styrene, acrylic acid or the like as the third monomer.

The polyacrylate emulsion is an emulsion containing at least one selected from a homopolymer of acrylate and methacrylate and a copolymer containing these esters as a main component.
Examples of the copolymer include copolymers with vinyl acetate, styrene, acrylonitrile, acrylamide, acrylic acid, and the like.

A polyurethane-based emulsion is a series of high-molecular-weight polyurethane resin emulsions having urethane bonds in the polymer.

The EVOH emulsion is an emulsion containing EVOH as a main component.

Latex is an emulsion in which rubber particles are dispersed in water.
1,4-polyisoprene latex, SBR (styrene-butadiene rubber) latex, NBR (acrylonitrile-butadiene rubber) latex, CR (chloroprene rubber) latex, VP latex (SBR latex copolymerized with vinylpyridine monomer), MBR
(Methyl acrylate-butadiene copolymer) latex, SB (styrene-butadiene copolymer) latex and the like.

A plasticizer may be added to the resin aqueous solution or the resin dispersion. A plasticizer is a compound that is relatively hard to volatilize, and improves the processability or physical properties by being added to a polymer substance. Polyoxyethylene glycol, polyoxypropylene glycol, and the like are also one type of plasticizer, but other plasticizers include phosphate esters, phthalate esters, aliphatic monobasic acid esters, and aliphatic dibasic acid esters. , Glycols, glycerins and the like.

As described above, the resin is preferably blended as an aqueous solution or an aqueous dispersion, but the resin may be blended by adding a plurality of liquids sequentially or simultaneously. May be carried out by adding a liquid containing A liquid containing a plurality of types of resins in a dispersed or dissolved state depending on their water solubility may be used. Water containing the same type of resin as a solute and a dispersoid may be added.

Next, the case where inorganic fine particles are blended as an aqueous dispersion will be described. 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 low, and excessive water will be introduced into the system, so that resin may leak from the dewatering slit or the foam of the strand may cause extrusion failure. is there. On the other hand, if it is too high, the dispersibility may be reduced due to the re-aggregation of the fine particles, which may cause poor appearance and reduced oxygen barrier properties.

The blending amount of the inorganic fine particles in the production method of the present invention varies depending on the type of the inorganic fine particles. In general, the blending amount of the inorganic fine particles is preferably 0.001 to 50 parts by weight with respect to 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 is preferably 0.005 to 30 parts by weight, particularly preferably 0.01 to 10 parts by weight.

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 fiber, glass flake 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.

In order to improve the barrier property of EVOH, an inorganic layered compound may be 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.

The inorganic layered compound is preferably a swellable inorganic compound which swells or cleaves when immersed in water, and is preferably vermiculite, montmorillonite, or synthetic swellable fluorine mica in which lithium, sodium and the like are intercalated between layers. 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 case of micro sieve) (2) l = 2 ^0.5 × l ₅₀ (in 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 blending inorganic fine particles as an aqueous dispersion is particularly suitable for blending an inorganic layered compound having a high weight average aspect ratio (α) as described above. Dispersion of water in water-swellable inorganic substances such as montmorillonite promotes cleavage, and when added as an aqueous dispersion, EVOH improves the oxygen barrier properties of EVOH.

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, its amount 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 stick to each other (block) and cause 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 having a three-dimensional network structure of Si—O bonds formed by gelling 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 compounding amount 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, inorganic layered compounds and / or silicon oxide particles are preferable, but the other inorganic fine particles exemplified above are used alone or selected from the inorganic layered compounds and silicon oxide particles. It may be used together with at least one of them.

Hereinafter, the melting and kneading of the EVOH in the extruder will be described more specifically with reference to FIGS. FIGS. 1 and 2 show a cylinder of a twin-screw extruder and a screw arranged inside the cylinder in order to facilitate description of an embodiment of the present invention.

The raw material supply section 1 of the first extruder shown in FIG.
EVOH (component A) supplied from is heated and becomes a molten or semi-molten state and becomes a full flight screw portion 7
It is sent forward (rightward in the figure) by a. EVOH
The excess water is squeezed in the liquid removing section 2 and mixed in the reverse flight screw section 8a. In addition, EVOH
The water is sent to the full flight screw portion 7b, and the water vapor is released from the vent port 3 to further adjust the water content of the resin together with the pressure inside the extruder.

Subsequently, the EVOH is sent to the reverse flight screw section 8b, and if necessary, the component C (for example, carboxylic acid, boron compound, phosphoric acid compound, alkali metal salt, And at least one selected from alkaline earth metal salts) in a molten state. Dewatered, but kneaded with additives E
VOH is still wet. Note that the temperature of the EVOH is controlled based on the temperature measured by the temperature sensor 5 disposed in the final full flight screw section 7c in the subsequent stage.

The water content of the EVOH resin composition extruded from the first extruder is controlled to 5 to 40% by weight. If the water content is too high, the resin and water contained in the resin are likely to undergo phase separation, and the strand immediately after discharge from the extruder is likely to foam. On the other hand, if the water content is too low, the viscosity of the resin increases, or it may cause thermal deterioration due to shear heat generation,
An excessive load is applied to the extruder, which may cause a failure. If the water content is not properly adjusted, when pellets are supplied to the second extruder, the pellets may be blocked by surface water. When the water content is within the above range, the extrusion stability in the second extruder is improved, and the quality and shape of pellets obtained from this extruder can be stabilized.

According to the embodiment, the water content can be adjusted by appropriately controlling the supply amount of water (including water contained in the washing liquid and the additives) to the extruder or the discharge amount of water from the extruder. Good.

The EVOH resin composition thus obtained is
It may be introduced into the second extruder as it is, or may be cut into pellets and then supplied to the second extruder. However, when a process of processing a part of the EVOH obtained from the first extruder into a molded product without passing through the second extruder is also used, a part of the pellet obtained by cutting is used. It is preferable to supply the mixture to the second extruder and pass the remainder to a drying step described later. In the illustrated form, at least a part of the EVOH resin composition (component A to which component C is added) discharged from the first extruder is introduced from the raw material supply unit 11 of the second extruder shown in FIG. Is done.

The EVOH introduced into the second extruder reaches the reverse flight screw section 18 via the full flight screw section 17a and is kneaded in a molten state with the component B supplied from the minor component addition section 14. In addition, EVOH
It is extruded through the full flight screw part 17b.
Also here, the temperature of the EVOH resin composition is measured by the temperature sensor 1 disposed in the subsequent full flight screw portion 17b.
The control may be performed based on the temperature measured in step 5. Second
The water content of the EVOH resin composition extruded from the extruder of 5 to 4 immediately after the extrusion for the same reason as described above.
It is preferably 0% by weight.

As described above, when a plurality of extruders are used, the ratio (L / D) of the screw length (L) to the screw diameter (D) of each extruder is reduced to a small range, for example, 20 to 5 times.
It can be suppressed to about 0.

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%.

EVOH having an ethylene content of 3 to 20 mol%
In any case of 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, pellets can be stably produced for the EVOH, and the component (component B) 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 first extruder is preferably 0.5% by weight or more, more preferably 5% by weight or more, particularly 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 preferably 50% by weight or less. If the water content exceeds 70% by weight, EVO
In the H resin 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 that a bridge is easily generated in the hopper of the extruder, which may adversely affect the productivity of pellets.

The method for adjusting the water content of EVOH before charging the first 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 EVOH is preferably a pellet obtained by cutting a strand precipitated in a coagulation bath, but the shape of the EVOH is not particularly limited as described above.
A crumb-like precipitate obtained by solidifying the paste in an irregular shape 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 residue of the saponification catalyst 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,
Even if the present invention is applied, an extruder having a large screw length (L) / screw diameter (D) is required to perform sufficient washing, which may cause 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. 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. In this way, the water content of the resin is adjusted together with the discharge of the cleaning liquid. Note that a plurality of injection sections and a plurality of liquid removal sections may be arranged.

With a dewatering slit or dewatering hole, 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 the molten resin may protrude from the dewatering holes, the dewatering slit is more preferable from such a viewpoint. Examples of the dewatering slit include a wedge wire type dewatering slit and a screen mesh type dewatering slit.

The dehydrating means exemplified above may be used alone, but a plurality of the same type may be used, or different types may be used in combination. For example, water may be removed from a resin having a high moisture content using a dewatering slit, and steam may be further removed from a vent port on the downstream side.

Next, additives selected from carboxylic acids, boron compounds, phosphoric acid compounds, alkali metal salts and alkaline earth metal salts will be described. Of course, these additives may be added alone, but it is preferable to improve various performances of EVOH by adding a plurality of types selected according to the embodiment.

Addition of a carboxylic acid to EVOH can improve thermal stability. 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 dried EVOH resin composition pellets 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 the alkaline earth metal salt is added to the 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 for 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 (aqueous solution) is preferable in consideration of the solubility of the additive, the merit in cost, the ease of handling, the 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.

When adding the above-mentioned additives such as carboxylic acid to EVOH as a solution, the lower limit of the amount of the solution to be added is 1 part by weight or more, and further 3 parts by weight, based on 100 parts by weight of the dry weight of EVOH. Parts or more, particularly preferably 5 parts by weight or more. The upper limit of the amount of the solution added is 50 parts by weight or less, and more preferably 30 parts by weight or less based on 100 parts by weight of the dry weight of EVOH.
It is preferably at most 20 parts by weight, especially at most 20 parts by weight. 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, it may be difficult to control the water content of the EVOH, and the resin and the water contained in the resin are easily separated in the extruder.

Conventionally, a treatment method of immersing EVOH in a treatment solution has been known, but in such a method, EVOH is used.
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.

[0091] The resin temperature in the first and second extruders is preferably 70 to 170 ° C. When various additives are mixed with EVOH in a molten state, the effect of improving dispersibility is higher.
VOH may not completely melt. The resin temperature is 8
0 ° C. or higher, particularly 90 ° C. or higher, is suitable. On the other hand, if the resin temperature exceeds 170 ° C., the EVOH is susceptible to thermal degradation. From such a viewpoint, the resin temperature is 150 ° C. or less,
Further, the temperature is preferably 130 ° C. or lower. The method for adjusting the resin temperature is not particularly limited, but a method for appropriately setting the temperature of the cylinder in the extruder is preferable. In particular, when a resin is blended as the component B in the second extruder, it is important to keep the resin temperature in the extruder within the above range.

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 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 pellet, the diameter of the die is 2 to 5 mmφ (φ is the diameter.
The same applies below), and the strand may be cut to a length of about 1 to 5 mm.

The pellets obtained from the second extruder (and, if necessary, the rest of the pellets obtained from the first extruder but not charged into the second extruder) are usually
It is 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,
A stationary drying method, a fluidized drying method, or the like is preferable, and a multi-stage drying process in which several drying methods are combined may be applied. Among them, a method of first 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 a 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.

It is also possible to blend the EVOH resin composition pellets obtained by the above method with EVOH having different degrees of polymerization, ethylene content and saponification degree and melt-mold. 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 incorporate 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 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 above-mentioned multilayer structure may be formed into various shapes as it is, but may be subjected to a stretching treatment in order 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.

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.

[0103]

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. The evaluation method of each characteristic is as follows.

(1) Measurement of water content 20 g of water-containing EVOH as a sample was placed in a well-dried weighing bottle, dried at 120 ° C. for 24 hours with a hot air drier, and the following equation was obtained from the change in 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 trace components Quantification was performed according to the following method. In the following, the term "dry chips" refers to an EV to 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.
It is obtained by drying the OH resin composition pellets 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 put into 100 ml of water.
Heat extraction was performed at 95 ° C for 6 hours. The extract was subjected to neutralization titration with 1 / 50N NaOH using phenolphthalein as an indicator 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 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 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) Single-Layer Film Forming Test A single-layer film formation of EVOH dry 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.

(3-a) 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 full Flight type, surface nitrided steel Rotation speed 40 rpm Driving machine DC motor SCR-DC218B manufactured by Sumitomo Heavy Industries, Ltd. Motor capacity DC 7.5 kW (rated 45 A) Heater 4-split type Die width 300 mm Resin temperature in die 240 ° C. Take-off speed 10 m / min

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

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

Example 1 Ethylene content of 44 mol%,
EVOH pellets having a saponification degree of 99.5 mol%, a melt index of 5 g / 10 min when dried, and a water content of 50 wt% are charged from the raw material supply section 1 of the first extruder having a structure similar to that shown in FIG. Then, excess water is derived from the liquid removing part (liquid removing slit) 2 and excess water vapor is derived from the vent port 3, respectively.
An aqueous solution composed of acetic acid / boric acid / potassium dihydrogen phosphate was added from the minor component addition section 4.

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

The specifications of the first extruder are shown below (the configuration is the same as in FIG. 1). Type Twin screw extruder L / D 30 Caliber 30mmφ Screw Co-rotation complete meshing type Rotational speed 300rpm Motor capacity DC22KW Heater 9-segment type Number of die holes 5 holes (3mmφ) Resin temperature in extruder 100 ° C Take-off speed 5m / min

The strand discharged from the die of the first extruder is used as a fan cutter (“FC-1” manufactured by Hoshi Plastics Co., Ltd.).
08S-1 ") to give EVOH pellets. The water content of the pellets was 20% by weight.

The EVOH pellet (component A) was mixed with the EVOH pellet shown in FIG.
Of the second extruder having the same structure as that shown in FIG. Further, a PVA aqueous solution was introduced as the component B from the trace component addition section 14. The input amount of the pellets per unit time was 6.25 kg / hour (including the weight of the contained water), and the input amount of the PVA aqueous solution was 1.25 L / hour. The added PVA aqueous solution is PV
A (Kuraray Co., Ltd. "PVA-105") using
It was prepared by adding to water at 20% by weight while heating to about 40 ° C.

After the strand discharged from the die was cooled in a water bath, an EVOH resin composition pellet was obtained using a fan cutter. The water content of the resin composition immediately after discharge from the extruder was 33% by weight.

The specifications of the second extruder are shown below (the configuration is the same as in FIG. 2). Type Twin screw extruder L / D 30 Caliber 30mmφ Screw Co-rotation complete meshing type Rotation speed 300rpm Motor capacity DC22kW Heater 9 division type Number of die holes 5 holes (3mmφ) Resin temperature in the extruder 140 ° C Take-off speed 5m / min

The obtained pellets were subjected to 1
The resultant was dried at 00 ° C. for 25 hours, and subsequently dried at 100 ° C. for 15 hours using a stationary dryer. As a result, the water content was 0.1% by weight. The content of acetic acid in the EVOH resin composition pellets after drying is 200 ppm, the content of boron compound is 270 ppm in terms of boron, the content of phosphate compound is 20 ppm in terms of phosphate, and the content of alkali metal salt is potassium. Was 6 ppm.

Using the obtained dried chips, a single-layer film formation of EVOH was performed. When the film surface of the obtained film-formed product was observed, no aggregate of PVA was observed, and no coloring due to thermal deterioration of EVOH was observed.

Example 2 An EVOH emulsion as an aqueous dispersion was used as a component B, and EVOH emulsion was prepared in the same manner as in Example 1.
A resin composition pellet was obtained. As an EVOH emulsion, sodium 2-acrylamido-2-methylpropanesulfonate unit is 1.2 mol% with respect to EVOH.
A sulfonic acid anion-modified EVOH having a random copolymerized ethylene content of 33 mol%, a saponification degree of 99.6 mol%, and a melt index of 10 g / 10 min is used as a dispersion stabilizer,
A dispersoid having an ethylene content of 32 mol%, a saponification degree of 99.5 mol%, and a melt index of 1 g / 10 min, having an average particle diameter of 0.7 μm and a solid concentration of 26% by weight was used. As a result of the single-layer film forming test, no agglomerate was observed, and there was no coloring due to thermal deterioration of EVOH, and the appearance was extremely good.

Comparative Example 1 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 from a metal plate having a circular opening into water to precipitate a strand, and cut to obtain a pellet 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 EVOH pellets (water content: 55% by weight) thus obtained were mixed with an acetic acid concentration of 0.1 g / L.
It was immersed in 6 L of an aqueous solution having a potassium dihydrogen phosphate concentration of 0.04 g / L and a boric acid concentration of 0.7 g / L at room temperature for 6 hours. After immersion, the solution was drained to obtain EVOH pellets having a water content of 55% by weight. Further, the pellets were put into a fluidized drier, and were then placed at 80 ° C. for 15 hours.
After drying at 0 ° C. for 24 hours, EV having a moisture content of 0.3% by weight
OH pellets were obtained. The obtained EVOH pellets were 100 ppm of acetic acid, and the boron compound was 270 p in terms of boron.
pm, the phosphate compound was 20 ppm in terms of a phosphate group, and the alkali metal salt was 10 ppm in terms of potassium. The melt index was 1.5 g / 10 minutes.

The obtained EVOH pellets were added to the raw material supply section 11 of the extruder having the same structure as shown in FIG.
g / h, and the resin concentration was 20% by weight in the same manner as in Example 1.
Of the PVA aqueous solution of
2.5 L / hr was added. The resin temperature in the extruder of this extruder was 250 ° C., the resin composition after discharge was intensely colored, and the resin composition foamed violently at the discharge port, and the sample was not collected.

Comparative Example 2 The ethylene content supplied to the extruder in Comparative Example 1 was 44 mol%, the saponification degree was 99.5 mol%, the water content was 0.3 wt%, and the melt index was 1.5 g.
Example 1 in 100 parts by weight of EVOH pellets
PVA (Kuraray Co., Ltd. “PVA-10
5 "), and added to a tumbler (NISSUI).
The mixture was mixed well for 5 minutes using KAKO (manufactured by KAKO). The obtained mixture of EVOH and PVA was charged at a rate of 10 kg / hour into a raw material supply section 11 of an extruder having a structure similar to that shown in FIG. 2, and was melt-extruded at a resin temperature of 250 ° C. in the extruder.

The water content of the resin composition obtained from the discharge port was 0.1% by weight. The resin composition pellets were dried at 100 ° C. for 25 hours using a fluidized drier. After drying, the water content of the obtained resin composition was 0.1% by weight. After the drying was completed, an inspection revealed that a large amount of fine powder had adhered to the inner wall surface of the fluidized dryer. When a large amount of fine powder is generated in this way, the fine powder stays in the dryer and undergoes thermal deterioration,
This may cause a reduction in quality during film formation, which is not preferable.

Next, a single-layer film was formed from the obtained resin composition pellets, and the appearance and coloring of the formed film were evaluated. As a result, agglomerates were observed on the entire surface of the film, the appearance was poor, and yellowing was severe.

Example 3 EVOH pellets having an ethylene content of 44 mol%, a saponification degree of 99.5 mol%, a melt index of 5 g / 10 min when dried, and a water content of 50 wt% used in Example 1 were obtained by An extruder having a structure similar to that shown in FIG. The processing solution consisting of acetic acid / boric acid / potassium dihydrogen phosphate aqueous solution was 0.25 L
/ H. The resin temperature in the extruder was 100 ° C. The extruded resin composition was pelletized in the same manner as in Example 1 to obtain EVOH pellets having a water content of 20% by weight.

The EVOH pellets were charged at a rate of 6.25 kg / hour to the raw material supply section 11 of the extruder having the same structure as shown in FIG.
Further, an aqueous dispersion of inorganic fine particles was added at 1.25 L / hour. The resin temperature in the extruder was 100 ° C and the resulting EV
The water content of the OH pellet was 33% by weight. The aqueous inorganic fine particle dispersion solution has 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), swellable fluoromica (“Somasif” (registered trademark) manufactured by Corp Chemical Co., Ltd.)
ME-100) was added to water so as to be 8.0% by weight, and stirred for about 15 minutes using a Henschel mixer to adjust.

[0134] The obtained pellets were subjected to 1
After drying at 00 ° C. for 25 hours and subsequently using a stationary dryer at 100 ° C. for 15 hours, the water content was 0.1% by weight. The content of acetic acid in the EVOH resin composition pellets after drying is 100 ppm, the content of the boron compound is 270 ppm in terms of boron, the content of the phosphate compound is 20 ppm in terms of the phosphate group, and the content of the alkali metal salt is potassium. It was 6 ppm in terms of metal.

Using the obtained dried chip, 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 inorganic fine particles were observed, and the film surface was good. In addition, there was no coloring due to thermal deterioration of the EVOH, and the appearance was extremely good.

Example 4 A resin composition was obtained in the same manner as in Example 3, except that the composition of the inorganic fine particle dispersion was changed.
The aqueous dispersion of inorganic fine particles was prepared as follows. As the inorganic layered compound, an average particle diameter of 100 to 2000 (n
m), aspect ratio 320 (average), surface area 25 (m ²⁾
/ G) of montmorillonite (“Kunipia (registered trademark) F” manufactured by Kunimine Industries Co., Ltd.)
It was added to water so as to obtain a weight%, and 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.

Example 5 A resin composition was obtained in the same manner as in Example 3, except that the composition of the inorganic fine particle dispersion was changed. The aqueous dispersion of inorganic fine particles was prepared as follows. As porous synthetic silica, an average particle size of 1.4 μm (Coulter counter method), a surface area of 300 (m ² / g, B
ET method) "Sylysia (registered trademark) 310" (manufactured by Fuji Silysia Chemical Ltd.) was used. Water was added to the 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 monolayer 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 film was excellent in blocking resistance and a good winding roll without wrinkles was obtained.

Comparative Example 3 The ethylene content used in Comparative Example 1 was 44 mol%, the saponification degree was 99.5 mol%, the water content was 0.3 wt%, the melt index was 1.5 g / 10 min,
The EVOH pellets were charged at a rate of 10 kg / hour into a raw material supply section 11 of an extruder having a structure similar to that shown in FIG. Added at 0.5 L / hr.

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

Comparative Example 4 EVOH pellets 100 used in Comparative Example 1 were an ethylene content of 44 mol%, a saponification degree of 99.5 mol%, a water content of 0.3 wt% and a melt index of 1.5 g / 10 min. 2 parts by weight of the aqueous dispersion of the inorganic fine particles used in Example 3 was added to parts by weight, and a tumbler (manufactured by NISSUI KAKO) was added so that the whole was mixed well.
For 5 minutes. Using a mixture of the obtained EVOH and swellable fluoromica, it was charged at a rate of 10 kg / hour into a raw material supply section of an extruder having a structure similar to that shown in FIG. A composition pellet was obtained. The obtained pellets were placed in a fluidized drier for 100
As a result of drying at 25 ° C. for 25 hours, the water content was 0.1% by weight.

After drying, a single-layer film was formed using the obtained EVOH resin composition pellets, and the appearance and coloring of the film-formed product were evaluated. As a result, aggregates due to the inorganic fine particles were observed on the entire surface of the film, and the yellowing was severe due to thermal degradation of the EVOH, and the appearance was poor.

(Comparative Example 5) EVOH pellets 100 used in Comparative Example 1 were 100 mol% ethylene, 99.5 mol% saponification, 0.3 wt% water content, and 1.5 g / 10 min melt index. 1 part by weight of “Sylysia (registered trademark) 310” used in Example 5 was added to parts by weight,
Tumbler so that the whole mixes well (NISSUI K
(AKO)) for 5 minutes.

A mixture of the obtained EVOH and “Sylysia (registered trademark) 310” was introduced at a rate of 10 kg / hour into a raw material supply section of the extruder 2 shown in FIG.
C., and EVOH resin composition pellets were obtained in the same manner as in Comparative Example 2. The obtained pellets were placed in a fluidized drier for 100
As a result of drying at 25 ° C. for 25 hours, the water content was 0.1% by weight.

After drying, a single-layer film was formed using the obtained EVOH resin composition pellets, and the appearance and coloring of the film-formed product were evaluated. As a result, the entire film became cloudy and poor in transparency, and aggregates due to inorganic fine particles were observed on the entire surface of the film. Further, a film having severe yellowing due to thermal deterioration of the EVOH and having a remarkably poor appearance was obtained.

In each of the above Examples and Comparative Examples,
Tables 1 to 4 show details such as the extrusion conditions, the composition of the processing solution, and the analysis results of the pellets.

(Table 1) Extrusion conditions: First extruder ―――――――――――――――――――――――― EVOH Trace component Resin Water content ( %) Amount Aqueous solution Temperature Injection Discharge (kg / hr) (L / hr) (° C) Before / after Immediately ― Example 1 10 0.25 100 50 20 Example 2 10 0.25 100 50 20 Example 3 10 0.25 100 50 20 Example 4 10 0.25 100 50 20 Example 5 10 0.25 100 50 20 ――――――――― ―――――――――――――――――――: Second extruder ――――――――――――――――――――――― ―――――――――― EVOH component B Resin Moisture content (%) Charge amount Type Addition amount Addition temperature Input Discharge (kg / hr) (L / hr) (% by weight) (° C) Before and after ― ―――――――――――――――――――――――――――――――――― Example 1 6.25 PVA (20) 1.25 5 100 20 33 Example 2 6.25 EVOH (26) 1.25 6.5 100 20 33 Comparative Example 1 10 PVA (20) 2.5 5 250 0.1 Foaming Comparative Example 2 10 PVA (-) ― 5 250 0.1 0.1 Example 3 6.25 ME-100 (8 ) 1.25 2 100 20 33 Example 4 6.25 Kunidia F (4) 1.25 1 100 20 33 Example 5 6.25 Sylysia 310 (4) 1.25 1 100 20 33 Comparative Example 3 10 ME-100 (8) 2.50 2 250 0.1 Foaming Comparison Example 4 10 ME-100 (―) ― 2 250 0.1 0.1 Comparative Example 5 10 Thyristia 310 (―) ― 1 250 0.1 0.1 ―――――――――――――――――――――― ――――――――――――― ・ Values added to component B are resin concentration or solid content concentration (% by weight) ・ "ME-100" is swellable fluoromica, "Kunidia F" is montmorillonite, "Sylysia 310" is porous synthetic silica.-EVOH (ethylene content: 44 mol%, saponification degree: 99.5 mol%) is charged by weight of EVOH including volatile components.-Each comparative example is the second extrusion. Use only machine

(Table 2) Composition of treatment solution ――――――――――――――――――――― Acetate Boric acid Phosphate compound (g / L) (g / L) (g / L L) ――――――――――――――――――――― Example 1 2.2 30 0.6 Example 2 2.2 30 0.6 Comparative Example 1 0.1 0.7 0.04 Comparative Example 2 0.1 0.7 0.04 Example 3 2.2 30 0.6 Example 4 2.2 30 0.6 Example 5 2.2 30 0.6 Comparative Example 3 0.1 0.7 0.04 Comparative Example 4 0.1 0.7 0.04 Comparative Example 5 0.1 0.7 0.04 ――――――――――――――――― --- Phosphoric acid compound is KH ₂ PO ₄

(Table 3) Composition of resin composition ―――――――――――――――――――――――――――――― Acetate Boric acid Phosphate Compound Alkali Metal salt (ppm) (ppm) (ppm) (K: ppm) ―――――――――――――――――――――――――――――――― 1 100 270 20 6 Example 2 100 270 20 6 Comparative Example 1 100 270 20 10 Comparative Example 2 100 270 20 10 Example 3 100 270 20 6 Example 4 100 270 20 6 Example 5 100 270 20 6 Comparative Example 3 100 270 20 10 Comparative Example 4 100 270 20 10 Comparative Example 5 100 270 20 10 ――――――――――――――――――――――――――――――――・ Boric acid concentration is equivalent to boron ・ Phosphate compound concentration is equivalent to phosphate radical ・ Alkali metal salt concentration is equivalent to alkali metal

(Table 4) Evaluation results (Film forming quality) ―――――――――――――――――― Appearance Coloring ―――――――――――――――――― -Example 1 Good None Example 2 Good None Comparative Example 1 (No sample was obtained due to foaming) Comparative Example 2 Agglomerated yellowing Example 3 Good None Example 4 Good None Example 5 Good None Comparative Example 3 ( Comparative Example 4 Agglomerate yellowing Comparative Example 5 Agglomerate yellowing ――――――――――――――――

In each of the examples, the stability of the strands obtained from the first and second extruders was excellent.
The shape of the pellet obtained by cutting was also good.

[0153]

As explained in detail above, according to the present invention, a small quantity and variety of EVOH can be produced efficiently and stably. In addition, EVOH having excellent dispersibility of the added trace components can be obtained. Given the diversification of EVOH applications, the utility of the present invention in the art is extremely high.

[Brief description of the drawings]

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

FIG. 2 is a side view showing a cylinder and a screw of a twin-screw extruder of a second extruder that can be used for carrying out one embodiment of the present invention.

[Explanation of symbols]

1, 11 Raw material supply section 2 Dewatering section 3 Vent port 4, 14 Trace component addition section 5, 15 Temperature sensor 7a, 7b, 7c, 17a, 17c Full flight screw section 8a, 8b, 18 Reverse flight screw section

──────────────────────────────────────────────────の 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 B 101/00 101/00 (72) Inventor Kawahara Takaharu 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 in Kuraray Co., Ltd. 4F070 AA02 AA03 AA13 AA26 AA28 AA38 AA52 AA53 AA54 AB01 AB09 AC12 AC20 AC40 AC42 FA03 FB07 FC05 4F201 AA04E AA19E AB16 AB19 AC01 AG01 AG07 AR06 AR20 BA01 BC01 BC12 BC33 BC37 BD05 BK02 BK13 BK27 BK73 BN21 4J002 AB022 AB032 002 BB13 BB03 002 DH03 DK00 EF03 EG02 EG03 FD01 FD02 FD05 FD07 FD10 FD13 GG02

Claims (13)

[Claims] 1. The method according to claim 1, wherein the water content extruded from the first extruder is 5
At least a part of the ethylene-vinyl alcohol copolymer resin (component A) of about 40% by weight is introduced into the second extruder, and the added component ( A method for producing an ethylene-vinyl alcohol copolymer resin composition, comprising mixing and kneading component B), followed by discharging. 2. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the component B is blended as a solute contained in the solution or a dispersoid contained in the dispersion. 3. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein a component (component C) other than the component A and the component B is introduced into the first extruder. 4. Component C is a carboxylic acid, a boron compound,
The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 3, which is at least one selected from a phosphoric acid compound, an alkali metal salt, and an alkaline earth metal salt. 5. A method for feeding water to the first extruder, removing water from the first extruder, or supplying water to the first extruder and water from the first extruder. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 4, wherein the water content of the resin in the first extruder is adjusted by combining removal with the resin. 6. The extruder according to claim 1, wherein a part of the pellets obtained by cutting the ethylene-vinyl alcohol copolymer resin discharged from the first extruder is introduced into the second extruder. A method for producing an ethylene-vinyl alcohol copolymer resin composition of the above. 7. The ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the water content of the resin composition immediately after being discharged from the second extruder is 5 to 40% by weight. Manufacturing method. 8. The temperature of the molten resin in the second extruder is 70
The method for producing an ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 7, wherein the temperature is from 170 to 170C. 9. The process for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the amount of the component B is 0.01 to 200 parts by weight based on 100 parts by weight of the component A. 10. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the component B is a resin, and the resin is blended as an aqueous solution or an aqueous dispersion. 11. The method for producing an ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the component B is inorganic fine particles, and the inorganic fine particles are blended as an aqueous dispersion. 12. The ethylene-vinyl alcohol copolymer resin composition discharged from the second extruder by the method according to claim 1 is cut into pellets, and then has a water content of 1 weight. %. The method for producing pellets of the ethylene-vinyl alcohol copolymer resin composition, wherein the pellets are dried until the amount becomes less than or equal to 10%. 13. A pellet obtained by cutting the ethylene-vinyl alcohol copolymer resin composition discharged from the second extruder by the method according to claim 6, and a pellet obtained by cutting the pellet obtained from the first extruder. A method for producing pellets of an ethylene-vinyl alcohol copolymer resin composition, characterized in that the remainder is dried until the water content becomes 1% by weight or less.