JP2000043040A - Production of saponified ethylene-vinyl acetate copolymer composition pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a saponified ethylene-vinyl acetate copolymer composition excellent in long-run moldability and free from fine fish-eyes when becoming multilayer laminate. SOLUTION: After containing at least one of a boron compound, a phosphoric acid compound, and a fatty acid alkaline earth metal salt by contacting a saponified ethylene-vinyl acetate copolymer pellet with at least one solution selected from a boron compound, a phosphoric acid compound, and a fatty acid salt, a resin composition pellet obtained by being dried to the water content 0.001-10 wt.% is melted and kneaded, so as to form a pellet again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing pellets of a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) composition, and more particularly to a method for producing a multilayer laminated body by melt molding. The present invention relates to a method for producing an excellent EVOH composition pellet.

[0002]

2. Description of the Related Art In general, EVOH is excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance and the like. It is used after being formed into materials, films and sheets of packaging materials for agricultural chemicals, containers such as bottles, and the like.

[0003] In such molding, usually, melt molding is performed, and by such molding, it is processed into a shape such as a film shape, a sheet shape, a bottle shape, a cup shape, a tube shape, a pipe shape, etc., and is provided for practical use. Its workability (formability) is very important, and in general, mechanical strength, moisture resistance,
In order to impart heat sealability and the like, the laminate is coextruded with a base material such as a polyolefin resin via an adhesive resin layer to form a laminate, and the interlayer adhesion is also important. In order to improve such moldability and interlayer adhesion, a compound of boron is added to EVOH (Japanese Patent Application Laid-Open Nos. 59-192564, 55-12108, and 49-2020).
No. 615, etc.) and compounding a phosphoric acid compound with EVOH (JP-A-52-954, JP-A-62-143).
954, JP-A-2-235952, etc.), E
Compounding acetate with VOH (JP-A-56-4120)
No. 4, JP-A-64-66262).

[0004]

However, in order to cope with the recent increase in performance required for a new molded product, the above-mentioned technology has been studied in detail, and as a result, a fisheye having a diameter of 0.1 mm or more has been obtained. Although improvements such as gels and the like are recognized, small ones of less than 0.1 mm are not necessarily solvable with the above technology,
In particular, sufficient consideration has not been given to the production of the multilayer laminate, and it is not possible to set the thickness of the multilayer laminate in accordance with the molding conditions.
Fish eyes less than 1 mm may occur,
It has been found that new improvements are desired.

[0005]

In view of this situation, the present inventors have conducted intensive studies on a treatment method after adding a boron compound, a phosphoric acid compound, and a fatty acid salt to EVOH. Pellets the boron compound,
After contacting with at least one aqueous solution selected from a phosphoric acid compound and a fatty acid salt to contain at least one of a boron compound, a phosphoric acid compound and a fatty acid salt, the water content is 0.00
By melt-kneading the resin composition pellets obtained by drying to 1 to 10% by weight, excellent melt moldability is obtained, and in particular, generation of fish eyes having a diameter of less than 0.1 mm is suppressed during production of a multilayer laminate. It has been found that EVOH composition pellets which can be formed and have good long-run moldability can be obtained, and the present invention has been completed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[0007] The EVOH used in the present invention is not particularly limited, but has an ethylene content of 20 to 60 mol%.
(More preferably 25 to 55 mol%), and those having a degree of saponification of 90 mol% or more (furthermore, 95 mol% or more) are used. On the other hand, if it exceeds 60 mol%, sufficient gas barrier properties cannot be obtained, and if the saponification degree is less than 90 mol%, the gas barrier properties, heat stability, moisture resistance, etc. decrease. Is not preferred.

EVOH has a melt index (MI) (210 ° C., load 2160 g) of 0.1 to 10;
The melt index is preferably 0 g / 10 min (more preferably 0.5 to 50 g / 10 min). If the melt index is smaller than the above range, the inside of the extruder will be in a high torque state during molding and extrusion processing will be difficult. If it is larger than the above range, the melt moldability and the mechanical strength of the molded product are undesirably reduced.

The EVOH is obtained by saponifying an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer can be obtained by any known polymerization method, for example, suspension polymerization, emulsion polymerization, solution polymerization and the like. The saponification of the produced ethylene-vinyl acetate copolymer can also be performed by a known method.

The EVOH may be used in a small amount, such as α-olefin, unsaturated carboxylic acid compound, unsaturated sulfonic acid compound, (meth) acrylonitrile, (meth) acrylamide, vinyl ether, vinyl silane compound, vinyl chloride, styrene and the like. It may be "copolymerized" with other comonomers. Also, "post-modified" such as urethanization, acetalization, and cyanoethylation may be used as long as the gist of the present invention is not impaired.

The boron compound used in the present invention includes boric acid or a metal salt thereof such as calcium borate, cobalt borate, zinc borate (such as zinc tetraborate and zinc metaborate), aluminum borate. Potassium, ammonium borate (ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate, etc.), cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.), potassium borate (potassium metaborate, Potassium tetraborate, potassium pentaborate,
Potassium hexaborate, potassium octaborate, etc.), silver borate (silver metaborate, silver tetraborate, etc.), copper borate (cupric borate, copper metaborate, copper tetraborate, etc.), boric acid Sodium (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.), lead borate (lead metaborate, lead hexaborate, etc.), boric acid Nickel (nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate, etc.), barium borate (barium orthoborate, barium metaborate, barium diborate, barium tetraborate, etc.), bismuth borate , Magnesium borate (magnesium orthoborate, magnesium diborate,
Magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc.), manganese borate (manganese borate, manganese metaborate, manganese tetraborate, etc.), lithium borate (lithium metaborate, tetraborate) Lithium, lithium pentaborate, etc.), and borate minerals such as borax, carnite, inyoite, dwarf stone, syanite, and zeiberite, and the like. Preferred are borax, boric acid, and boric acid. Sodium (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.) is used.

The phosphate compound used in the present invention includes sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate,
Tripotassium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, tricalcium phosphate, magnesium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, zinc hydrogen phosphate, barium hydrogen phosphate, hydrogen phosphate Manganese and the like can be mentioned, and preferably, sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, and magnesium dihydrogen phosphate are used. Further, the fatty acid salt used in the present invention includes alkali metal salts (such as sodium salt and potassium salt) such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, and behenic acid, and alkaline earth salts (magnesium). Salts, calcium salts, barium salts, etc.), zinc metal salts, manganese metal salts, and the like. Potassium acetate, calcium acetate, and magnesium acetate are preferably used.

In the present invention, first, a boron compound, a phosphoric acid compound, or a fatty acid salt is added to EVOH. In this case, EVOH is brought into contact with an aqueous solution of the boron compound, the phosphoric acid compound, or the fatty acid salt. In this case, the concentration of the boron compound, the phosphoric acid compound or the fatty acid salt in the aqueous solution is 0.001 to 1% by weight in the case of the boron compound (further 0.003% by weight).
If it is less than 0.001% by weight, it becomes difficult to contain a predetermined amount of the boron compound. Conversely, if it exceeds 1% by weight, the appearance of the finally obtained molded product is deteriorated. Is not preferred. In the case of a phosphoric acid compound, it is 0.0001 to 1% by weight (further, 0.0005 to 1% by weight).
0.5% by weight), and if it is less than 0.0001% by weight, it becomes difficult to contain a predetermined amount of a phosphoric acid compound. Conversely, if it exceeds 1% by weight, the appearance of a finally obtained molded product is deteriorated. Is not preferred. Further, in the case of a fatty acid salt, the content is preferably 0.001 to 1% by weight (more preferably 0.01 to 0.5% by weight). If the content is less than 0.001% by weight, it becomes difficult to contain a predetermined amount of the fatty acid salt. If it exceeds 1% by weight, the appearance of the finally obtained molded product is undesirably reduced. When any two or more of a boron compound, a phosphoric acid compound and a fatty acid salt are used in combination, the respective concentrations preferably satisfy the above conditions.

The method of bringing EVOH into contact with such an aqueous solution is not particularly limited, but usually, it is preferable to add EVOH formed into pellets to the aqueous solution and to stir the above-mentioned compound while stirring.

In preparing (molding) the above EVOH pellets, a known method can be adopted.
For example, after a mixed solution of EVOH water and alcohol is extruded into a coagulating liquid into a strand or a sheet, the resulting strand or sheet may be cut into pellets. As the shape of such a pellet-shaped EVOH, a columnar shape, a spherical shape, or the like is preferable, and in the case of a columnar shape, the diameter is preferably 1 to 10 mm, and the length is preferably 1 to 10 mm,
In the case of a spherical shape, the diameter is preferably 1 to 10 mm. The EVOH preferably has a microporous internal structure in which pores having a diameter of about 0.1 to 10 μm are uniformly distributed. Usually, an EVOH solution (a mixed solvent of water / alcohol) is extruded into a coagulation bath. Sometimes, the concentration of the EVOH solution (20-80% by weight), the extrusion temperature (45-70%)
° C), type of solvent (water / alcohol mixture weight ratio = 80 /
20-5 / 95 etc.), temperature of coagulation bath (1-20 ° C), residence time (0.25-30 hours), EVOH in coagulation bath
By arbitrarily adjusting the amount (0.02 to 2% by weight) and the like, it becomes possible to obtain an EVOH having the structure. Further, those having a water content of 20 to 80% by weight are preferable because the compounds and the like can be uniformly and rapidly contained.

The content of the boron compound, the phosphoric acid compound and the fatty acid salt in the EVOH composition obtained by such a method is not particularly limited.
0.001 to 1 part by weight (more preferably 0.002 to 0.5 part by weight) in terms of boron based on 100 parts by weight,
If the amount is less than 0.001 part by weight, the effect of adding the boron compound is not sufficient, and if it exceeds 1 part by weight, the appearance of a finally obtained molded product is undesirably deteriorated. In the case of a phosphoric acid compound, 0.0005 to 0.1 part by weight (further, 0.0005 to 0.1 part by weight of phosphoric acid radical) with respect to 100 parts by weight of EVOH.
When the amount is less than 0.0005 parts by weight, the effect of adding the phosphoric acid compound is not sufficient. On the contrary, when the amount exceeds 0.1 parts by weight, the appearance of the finally obtained molded product is poor. It is not preferable because it decreases. In the case of a fatty acid salt, E
0.001 to 100 parts by weight of VOH in terms of metal
0.05 parts by weight (further 0.002 to 0.03 parts by weight)
When the amount is less than 0.001 part by weight, the effect of adding the fatty acid salt is not sufficient, and when the amount exceeds 0.05 part by weight, the appearance of a finally obtained molded product is unfavorably deteriorated. 2 out of boron compounds, phosphoric acid compounds and fatty acid salts
When two or more species are used in combination, it is preferable that their contents satisfy the above conditions.

In adjusting the content of the above-mentioned compounds and the like, there is no particular limitation. In the above-mentioned contact treatment with the aqueous solution, the concentration of the aqueous solution of the compounds and the like, the contact treatment time, the contact treatment temperature, the stirring speed during the contact treatment, and the like. It is possible by controlling the water content of the EVOH to be treated.

As described above, a boron compound, a phosphoric acid compound,
The EVOH composition pellets containing at least one fatty acid salt are then dried to a moisture content of 0.001 to 10% by weight (further 0.01 to 5% by weight, especially 0.1 to 2% by weight). When the water content is less than 0.001, the long-run moldability of the EVOH composition deteriorates, and when it exceeds 10% by weight, the melt kneading can be stably performed in the next melt kneading step. However, the object of the present invention cannot be achieved.

For the drying, a known method can be adopted. For example, a cylindrical / groove type stirring dryer, a cylindrical dryer, a rotary dryer, a fluidized bed dryer, a vibration fluidized bed dryer,
Drying may be performed by fluidized drying using a conical rotary dryer or static drying using a batch box dryer, band dryer, tunnel dryer, vertical silo dryer, or the like.

In the present invention, the dried EV
The greatest feature is that the OH composition pellets are melt-kneaded to produce a product (re-pelletization). There is no particular limitation on such melt-kneading, provided that the EVOH composition is sufficiently melt-kneaded. Well, for example, kneader ruder, extruder, mixing roll, banbury mixer,
A known kneading device such as a plast mill can be used,
Usually 120-300 ° C (more 150-280 ° C)
It is preferable to carry out melt kneading for about 2 minutes to 1 hour, and it is advantageous to use an extruder such as a single screw extruder or a twin screw extruder industrially. Extruder L [extruder screw length (mm)] / D [extruder screw diameter (m
m)] is 0.005 kW · hr /
kg or more (further 0.01 to 0.03 kWhr / k)
g) It is preferable to perform the melt kneading under the conditions such that
If the specific energy is less than 0.005 kW · hr / kg, the effect of suppressing fine fish eyes may be insufficient, which is not preferable.

Here, the specific energy means the energy given to the resin per unit discharge amount (1 kg) from the kneading equipment for the effect of kneading when the resin is melted and kneaded. Attach an ammeter, a voltmeter, etc., obtain the power consumption of the motor from this, multiply this by the power factor of the motor (normally about 0.85), and calculate the power amount per discharge amount (see (1) below). The specific energy for the resin is determined by the difference between the specific energy during resin extrusion and the specific energy during idle operation.

[0022]

E = (I _EX −I ₀ ) × E _EX × A × P _f / Q / LD / 1000 (1) (where E is the specific energy per L / D during melt mixing, I _EX is the current during resin extrusion (A), I ₀ is the current during idle operation (A), E _EX is the voltage (V), A is the power constant (1 for single phase, 1 for three-phase AC the 3 ^0.5), P _f is the power factor, Q is the resin extrusion amount per unit time (kg / hr), LD represent respectively the value of the screw L / D of the extruder) and, such specific energy 0. In order to make it 005 kw · hr / kg or more, it can be controlled by the screw shape of the extruder, L / D, the number of revolutions and the extrusion temperature, the charged amount of resin, the MI (melt index) of EVOH, and the like.

According to the method of the present invention as described above, an EVOH composition excellent in appearance and long-run moldability of a molded product can be obtained. If necessary, the composition may further include a plasticizer. It is also possible to use additives such as heat stabilizers, ultraviolet absorbers, antioxidants, coloring agents, antibacterial agents, fillers, and other resins. In particular, a hydrotalcite-based compound, a hindered phenol-based, a hindered amine-based heat stabilizer, and a metal salt of a higher aliphatic carboxylic acid can also be added as a gel generation inhibitor.

As the EVOH, two or more different EVOHs can be used. In this case, the ethylene content differs by 5 mol% or more and / or the saponification degree is 1%.
It is useful to use a blend of EVOH different in mole% since the stretchability at the time of high stretching and the secondary workability such as vacuum pressure forming and deep drawing can be improved while maintaining gas barrier properties.

The method for producing two or more different types of EVOH is not particularly limited. For example, a method of mixing each paste of EVA before saponification followed by saponification, an alcohol of each EVOH after saponification or a mixed solution of water and alcohol And a method of mixing and kneading each EVOH pellet after melt-kneading.

The EVOH resin composition thus obtained comprises:
It is often used for molded products, and pellets by melt molding etc.
It can be formed into films, sheets, containers, fibers, rods, tubes, various molded products, etc., and can also be subjected to melt molding again using these crushed products (such as when reused products) and pellets are used. As such a melt molding method, an extrusion molding method (T
-Die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.), and injection molding. The melt molding temperature is often selected from the range of 150 to 300 ° C.

The EVOH composition obtained according to the present invention can be used as a single layer.
In particular, the effect of the present invention can be sufficiently exerted when used for a laminate, and specifically, a thermoplastic resin layer or the like is laminated on at least one surface of a layer made of the EVOH composition to form a multilayer laminate. Useful to use.

In producing the laminate, the EV
The other substrate is laminated on one or both sides of the layer of the OH composition. As a lamination method, for example, a method of melt-extruding a thermoplastic resin into a film or sheet of the EVOH composition, and a method of laminating a thermoplastic resin A method of melt-extruding the EVOH composition on a substrate such as a method of coextruding the EVOH composition with another thermoplastic resin, and furthermore, a method of EVOH obtained by the present invention.
A method of dry laminating a film or sheet of the composition with a film or sheet of another substrate using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester-based compound, or a polyurethane compound is exemplified.

In the case of coextrusion, the mating resin may be linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene -Acrylate copolymer, polypropylene, propylene-α-olefin (having 4 to 20 carbon atoms)
Α-olefins) copolymers, polyolefins such as polybutenes and polypentenes, or polyolefins in a broad sense, such as homo- or copolymers of these olefins, or graft-modified homo- or copolymers of these olefins with unsaturated carboxylic acids or esters thereof Resin, polyester, polyamide, copolymerized polyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene, vinyl ester resin,
Examples thereof include polyester elastomer, polyurethane elastomer, chlorinated polyethylene, and chlorinated polypropylene. EVOH can also be co-extruded. Among them, polypropylene, polyamide, polyethylene, ethylene-vinyl acetate copolymer, polystyrene, and PET are preferably used from the viewpoint of easiness of coextrusion film formation and practicality of film physical properties (particularly strength).

Furthermore, a molded product such as a film or a sheet is once obtained from the EVOH composition obtained in the present invention, and another substrate is extrusion-coated on this, or a film or sheet of another substrate is coated with an adhesive. In the case of laminating using, any substrate (paper, metal foil, uniaxially or biaxially stretched plastic film or sheet, woven fabric, nonwoven fabric, metal flocculent, woody, etc.) other than the above-mentioned thermoplastic resin can be used. .

The layer structure of the laminate is the same as the EV obtained by the present invention.
A (a ₁ , a ₂ ,...) Of the OH composition layer, another substrate,
For example, when the thermoplastic resin layer is b (b ₁ , b ₂ ,...), If it is a film, a sheet, or a bottle, not only a two-layer structure of a / b but also b / a / b, a / b / a, a ₁ /
Any combination such as a ₂ / b, a / b ₁ / b ₂ , b ₂ / b ₁ / a / b ₁ / b ₂ is possible.
b is bimetal type, core (a) -sheath (b) type, core (b)-
Any combination such as a sheath (a) type or an eccentric core-sheath type is possible.

The laminate is used as it is in various shapes. However, it is preferable to carry out a stretching treatment in order to further improve the physical properties of the laminate.
Either uniaxial stretching or biaxial stretching may be used. Stretching at the highest possible magnification is preferable in terms of physical properties, such as a stretched film or a stretched sheet which does not generate pinholes, cracks, stretch unevenness, delamination, etc. during stretching. Is obtained.

The stretching method includes a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, and the like.
Of the deep drawing, vacuum forming and the like, those having a high stretching ratio can be employed. In the case of biaxial stretching, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method can be adopted. Stretching temperature is 60
To 170 ° C, preferably about 80 to 160 ° C.

After the stretching is completed, heat setting is performed.
The heat setting can be performed by a well-known means, and heat treatment is performed at 80 to 170 ° C., preferably 100 to 160 ° C. for about 2 to 600 seconds while keeping the stretched film in a tensioned state.

When used for heat shrink wrapping of raw meat, processed meat, cheese, etc., the product film is formed without heat setting after stretching, and the raw meat, processed meat, cheese, etc. are stored in the film. After that, 50-130 ° C., preferably 70
The film is subjected to a heat treatment at about 120 ° C. for about 2 to 300 seconds to thermally shrink the film, thereby performing tight packaging.

The shape of the thus obtained laminate may be any shape, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and an extrudate having a modified cross section. Further, the obtained laminate is heat-treated, cooled, rolled, printed, dry-laminated,
Solution or melt coating processing, bag making processing, deep drawing processing, box processing, tube processing, split processing, and the like can be performed.

The films, sheets or containers obtained as described above are useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

[0038]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 EVOH [Ethylene content 35 mol%, saponification degree 99.
5 mol%, MI (210 ° C, load 2160g) 20g
/ 10 min] solution (the solvent is a mixed solution of water / methanol = 40/60 weight ratio, EVOH content: 45%) is extruded into a coagulating liquid (5 ° C. water) in a strand form, and then cut with a cutter. , Porous EVOH pellets (length 5 mm,
5 mm in diameter). After washing these pellets with water, they are poured into a 0.1% boric acid aqueous solution, stirred at 30 ° C. for 5 hours, and dried at 110 ° C. for 7.5 hours to obtain a water content of 0.5%. EVOH composition pellet [the boron compound content is 0.00 in terms of boron with respect to 100 parts of EVOH.
4 parts].

Next, 100 parts of the obtained EVOH composition pellets were mixed with a vented single screw extruder (screw diameter 90 m).
m, L / D = 30), melt kneading at 210 ° C. and pelletizing at 210 ° C. under the condition that the specific energy for the composition is 0.012 kW · hr / kg per L / D. The resulting EVOH composition pellets were obtained.

The obtained EVOH composition was supplied to a multilayer extruder equipped with a feed block 5-layer T-die, and a polyethylene layer (“Novatech LD LF525” manufactured by Mitsubishi Chemical Corporation) was used.
H ") / adhesive resin layer (" Modic AP2 "manufactured by Mitsubishi Chemical Corporation)
40H ”) / resin composition layer / adhesive resin layer (same as left) / polyethylene layer (same as left) and a multilayer laminate of 5 layers (thickness of 5).
0/10/20/10/50 (μm)), the generation of fine fish eyes having a diameter of less than 0.1 mm and the evaluation of long-run moldability were performed in the following manner. (Fish eye)

The film immediately after molding (10 cm × 1
0 cm), the occurrence of fish eyes having a diameter of 0.01 to less than 0.1 mm was visually observed and evaluated as follows.

◎ −−− 0 to 3 pieces ○ −−− 4 to 10 pieces △ −−− 11 to 50 pieces × −−− 51 or more (long-run moldability) Further, the above-mentioned molding is performed continuously for 10 days. Then, the molded film at that time was visually observed for the increase in fish eyes in the same manner, and evaluated as follows.

○ --- No increase was observed △ --- A slight increase was observed x --- A significant increase was observed Example 2 EVOH [ethylene] after saponification during EVOH production process Content 40 mol%, saponification degree 99.0 mol%, MI (2
10 ° C., load 2160 g) is 12 g / 10 min] solution (the solvent is a mixed solution of water / methanol = 20/80 weight ratio,
EVOH (containing 40%) is extruded into a coagulating liquid (water at 2 ° C.) in the form of a strand, and then cut with a cutter.
Pellets (length 5 mm, diameter 4 mm) were obtained. The pellet was washed with a 0.5% acetic acid aqueous solution, further washed with water, poured into a 0.06% magnesium dihydrogen phosphate aqueous solution, stirred at 35 ° C. for 4 hours, and then stirred at 105 ° C. for 1 hour.
After drying for 0 hour, EVOH composition pellets having a water content of 0.8% [a phosphate compound content was 0.012 parts in terms of phosphate group with respect to 100 parts of EVOH] were obtained.

Next, 100 parts of the obtained EVOH composition pellets were mixed with a vented single screw extruder (screw diameter 60 m).
m, L / D = 30), melt-kneaded at 200 ° C. and pelletized under the condition that the specific energy for the composition is 0.016 kW · hr / kg per L / D. An EVOH composition was obtained.

The obtained EVOH composition was evaluated in the same manner as in Example 1.

Example 3 EVOH after saponification during the EVOH production process [ethylene content 30 mol%, saponification degree 99.6 mol%, MI (2
10 ° C., load 2160 g) is 8 g / 10 min] solution (the solvent is a mixed solution of water / methanol = 50/50 weight ratio,
VOH (containing 35%) was extruded into a coagulating liquid (water at 5 ° C.) in the form of a strand and then cut with a cutter to give a porous E.
VOH pellets (length 4 mm, diameter 4 mm) were obtained. The pellet is washed with a 0.5% acetic acid aqueous solution, further washed with water, put into a 0.05% calcium acetate aqueous solution, stirred at 30 ° C. for 4 hours, and then dried at 105 ° C. for 9 hours. Thus, EVOH composition pellets having a water content of 1.4% [a calcium acetate content was 0.008 parts in terms of calcium with respect to 100 parts of EVOH] were obtained.

Next, 100 parts of the obtained EVOH composition (pellet) was subjected to a vented co-rotating twin-screw extruder (screw diameter: 87 mm, L / D = 30) to give a specific energy per L / D of the composition. 0.010kW · hr / k
The resulting EVOH composition was obtained by melt-kneading and pelletizing at 215 ° C. under the conditions of g.

The obtained EVOH composition was evaluated in the same manner as in Example 1.

Example 4 After washing the porous EVOH pellets obtained in Example 1 with water, the pellets were poured into an aqueous solution containing 0.2% boric acid and 0.03% magnesium acetate, and washed with water. After stirring at 4 ° C. for 4 hours, drying was carried out at 110 ° C. for 7 hours to obtain a water content of 0.1%.
8% EVOH composition pellet [Boric acid content is EVO
0.06 parts in terms of boron with respect to 100 parts of H, and a magnesium acetate content of 0.005 part in terms of magnesium with respect to 100 parts of EVOH].

Next, 100 parts of the obtained EVOH composition pellets were subjected to a vented co-rotating twin-screw extruder (screw diameter 40 mm, L / D = 32) so that the specific energy to the composition was 0.1% per L / D. Under the conditions of 013 kW · hr / kg, the mixture was melt-kneaded at 220 ° C. and pelletized to obtain a target EVOH composition.

The obtained EVOH composition was evaluated in the same manner as in Example 1.

Example 5 EVOH [ethylene content 40 mol%, saponification degree 98.
6 mol%, MI (210 ° C., load 2160 g) 25 g
/ 10 min] solution (the solvent is a mixed solution of water / methanol = 20/80 weight ratio, EVOH content is 40%) is extruded into a coagulating liquid (water at 2 ° C.) in the form of a strand and cut with a cutter. , Porous EVOH pellets (length 3 mm,
3 mm in diameter). After washing these pellets with water, they are poured into an aqueous solution containing 0.05% borax and 0.007% calcium dihydrogen phosphate, stirred at 30 ° C for 5 hours, and then at 120 ° C for 9 hours. After drying, the EVOH composition pellets having a water content of 0.15% [borax content is 0.03 part in terms of boron with respect to 100 parts of EVOH, and calcium dihydrogen phosphate content is 100 parts of EVOH with phosphate groups. 0.002 parts in conversion].

Next, 100 parts of the obtained EVOH composition pellets were mixed with a single screw extruder (screw diameter 40 mm, L / D
= 28), the specific energy for the composition is L / D
Under the condition of 0.021 kW · hr / kg
The mixture was melt-kneaded at 05 ° C. and pelletized to obtain a target EVOH composition.

The obtained EVOH composition was evaluated in the same manner as in Example 1.

Example 6 After washing the porous EVOH pellets obtained in Example 2 with water, 0.04% boric acid, 0.03% sodium dihydrogen phosphate and 0.03% acetic acid. After pouring into an aqueous solution containing calcium and stirring at 35 ° C. for 3 hours,
After drying at 10 ° C. for 7.5 hours, E having a water content of 0.5% was obtained.
VOH composition pellet [Boric acid content is EVOH100
Parts in terms of boron, 0.02 parts in terms of boron, a content of sodium dihydrogen phosphate of 0.009 parts in terms of phosphate radical, and a content of calcium acetate in the case of 100 parts of EVOH of EVOH10.
0.005 parts in terms of calcium with respect to 0 parts].

Next, 100 parts of the obtained EVOH composition pellets were mixed with a vented single screw extruder (screw diameter 90 m).
m, L / D = 30), melt kneading at 200 ° C. and pelletizing under the condition that the specific energy for the composition is 0.014 kW · hr / kg per L / D. An EVOH composition was obtained.

The obtained EVOH composition was evaluated in the same manner as in Example 1.

Example 7 In Example 1, the ethylene content of EVOH was 3
5 mol%, saponification degree 99.5 mol%, MI (210 ° C.,
80160 parts of EVOH having a load of 2160 g), ethylene content of 48 mol%, saponification degree of 96 mol%, MI
(210 ° C, load 2160g) EV 15g / 10min
Using a blend with 20 parts of OH, according to Example 1, a polypropylene layer ("Novatech PP" manufactured by Mitsubishi Chemical Corporation)
EA9 ") / adhesive resin layer (" Modic AP P512 "manufactured by Mitsubishi Chemical Corporation) / resin composition layer / adhesive resin layer (same as left) / polypropylene layer (same as left) / five-layer multilayer laminate (thickness 350 / 50/80/50/350 (μ
m)) and evaluated in the same manner as in Example 1.

A cup having a drawing ratio of 1.5 was formed from the multilayer laminate by a plug-assist type vacuum / pressure forming machine, and cracks and thickness unevenness of the obtained cup were examined. It was a good cup.

Comparative Example 1 In the same manner as in Example 1, the EVOH composition pellets having a moisture content of 0.1%, which were dried at 110 ° C. for 12 hours, were similarly evaluated without melt-kneading.

Comparative Example 2 An EVOH composition was obtained and evaluated in the same manner as in Example 1 except that the drying conditions were changed to 150 ° C. for 48 hours, and EVOH composition pellets having a water content of 0.0008% were used. Was done.

Comparative Example 3 The procedure of Example 1 was repeated except that the drying conditions were 80 ° C. for 12 hours and that the EVOH composition pellets having a water content of 15% were used. Water is fed back from the barrel part, making it impossible to extrude,
The target EVOH composition pellets could not be obtained, and subsequent evaluation could not be performed.

Table 1 shows the evaluation results of the examples and comparative examples.

[0065]

[Table 1]

[0066]

EFFECTS OF THE INVENTION The EVOH composition pellets obtained by the method of the present invention are free from the generation of fine fish eyes having a diameter of less than 0.1 mm when formed into a multilayer laminate, are excellent in long-run moldability, and have various properties. It is very useful for applications such as films, sheets, tubes, bags, and containers for packaging foods, pharmaceuticals, agricultural chemicals, and industrial chemicals, and is also suitable for secondary processed products with stretching. Can be used.

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Claims (4)

[Claims] 1. A saponified ethylene-vinyl acetate copolymer pellet is brought into contact with at least one aqueous solution selected from a boron compound, a phosphoric acid compound and a fatty acid salt to produce at least one of a boron compound, a phosphoric acid compound and a fatty acid salt. , A resin composition pellet obtained by drying to a water content of 0.001 to 10% by weight is melt-kneaded to obtain a pellet again, wherein the saponified ethylene-vinyl acetate copolymer composition is obtained. Of manufacturing material pellets. 2. The method for producing saponified ethylene-vinyl acetate copolymer composition pellets according to claim 1, wherein the melt-kneading is carried out by an extruder. 3. The specific energy per L [length of extruder screw (mm)] / D [diameter of extruder screw (mm)] during extrusion of the extruder is 0.005 kW · h.
The method for producing pellets of saponified ethylene-vinyl acetate copolymer composition according to claim 2, wherein the pellets are r / kg or more. 4. A saponified ethylene-vinyl acetate copolymer pellet comprising two saponified ethylene-vinyl acetate copolymers, wherein the saponified product has a difference in ethylene content of 5 mol% or more and / or saponified. The ethylene-polymer according to any one of claims 1 to 3, wherein the difference in the degree is 1 mol% or more.
A method for producing saponified vinyl acetate copolymer composition pellets.