JP2001105428A - Method for manufacturing pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pellet of a saponified ethylene-vinyl acetate copolymer or a saponified ethylene-vinyl acetate copolymer composition capable of obtaining a molding having a small changes in torque and discharge of an extruder during molding with excellent feedability to the extruder at melt molding and excellent dimensional accuracy such as shape and a thickness or the like. SOLUTION: A saponified ethylene-vinyl acetate copolymer or a saponified ethylene-vinyl acetate copolymer composition is extruded from a die nozzle to a strand-like state, then to cut it to manufacturing the pellet, a shearing speed γ at the nozzle and the surface temperature T of the saponified ethylene- vinyl acetate copolymer or the saponified ethylene-vinyl acetate copolymer composition at the time of cutting are held in a specific relationship.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) or pellets of an EVOH composition. Bite into the body)
EVOH with excellent excursion, small fluctuations in torque and discharge of the extruder during molding, and extremely good dimensional accuracy of the molded product obtained.
Alternatively, it relates to a pellet of the EVOH composition.

[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. In such molding, usually, EVOH pellets are charged into an extruder or the like, and are molded into a film or sheet by melt molding.
Depending on the properties of the pellet, the desired EVOH molded product may not be obtained. For example, the accuracy of the shape and thickness of the molded product may be reduced, and the properties of the pellets are becoming very important. In view of this, JP-B-47-38634 discloses that the methanol of EVOH -Water mixed solution with water below 50 ° C or methanol-
Extruded and extruded in a strand form into a water mixture to produce EV
A method for obtaining OH pellets is disclosed in JP-A-53-9898, in which an EVOH solution is discharged into water or a mixed solution of methanol and water from the pores of a die.
A method of separating a solution with a cutter to obtain spherical EVOH pellets is disclosed in Japanese Patent Application Laid-Open No. Sho 53-120767, in which a strand of a precipitated EVOH solution is fed to a cutting section through a specific introduction pipe. The method of obtaining EVOH pellets is
Japanese Patent Application Laid-Open No. Sho 62-106904 discloses a method of extruding an EVOH solution containing a lubricant into a coagulating liquid in a strand form to obtain EVOH pellets.
The publication describes a method in which a strand is introduced into a cutting section using a belt conveyor, and is cut while spraying water to obtain EVOH pellets.

[0003]

However, the above-mentioned JP-B-47-38634 and JP-A-53-9898 have been disclosed.
In the method disclosed in JP-A-62-106904, the feedability of the obtained EVOH pellets at the time of melt molding is insufficient, and in JP-A-53-120767 and JP-A-3-61507. Also in the disclosed method, although the pellet shape is relatively uniform, a certain effect on the feedability is recognized, but there is room for further improvement. In other words, from the market these days,
The demands on the accuracy of the shape and thickness of a molded product are becoming stricter, and the emergence of EVOH pellets that can meet such demands is awaited.

[0004]

Accordingly, the present inventor has made extensive studies in view of the present situation, and as a result, produced a pellet by extruding EVOH or an EVOH composition from a die nozzle into a strand and cutting it. In the meantime, it has been found that the above object can be achieved by satisfying the following expression (1) as the relationship between the shear rate (γ) at the die nozzle and the surface temperature (T) of the EVOH or the EVOH composition at the time of cutting. Thus, the present invention has been completed. 1.5 × 10 ³ <(γ · T) <3 × 10 ⁵ (1) where γ is the shear rate (sec ⁻¹ ) and T is the surface temperature (° C.) of EVOH or the EVOH composition, respectively. Represent.
In measuring the surface temperature, an infrared reflection thermometer or the like can be used. Further, in the present invention, EVOH or EVOH supplied to the die nozzle
When the melt-kneading conditions of the composition satisfy the following formula (2), the effect of the present invention can be remarkably obtained. 10 <(L / D) <100 (2) where L represents the length (mm) of a screw of an extruder used for melt-kneading, and D represents the diameter (mm) of the screw.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The EVOH used in the present invention is not particularly limited, but has an ethylene content of 20 to 60 mol% (furthermore, 25%).
~ 55 mol%), and the degree of saponification is 90 mol% or more (further 9%).
When the ethylene content is less than 20 mol%, the gas barrier properties and melt moldability at high humidity are reduced, and when it exceeds 60 mol%, sufficient gas barrier properties are obtained. In addition, if the saponification degree is less than 90 mol%, the gas barrier properties, thermal stability, moisture resistance, etc. decrease, which is not preferable. Also, the melt flow rate (MFR) of the EVOH
(210 ° C., load 2160 g) is 0.1 to 100 g /
10 minutes (more preferably 0.5 to 50 g / 10 minutes) is preferred,
When the MFR is smaller than the above range, the inside of the extruder is in a high torque state during molding and extrusion processing becomes difficult. When the MFR is larger than the above range, the mechanical strength of the molded product is insufficient, which is not preferable. .

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, solution polymerization,
It is produced by suspension polymerization, emulsion polymerization, or the like, and saponification of an ethylene-vinyl acetate copolymer can also be performed by a known method. In the present invention, a copolymerizable ethylenically unsaturated monomer may be copolymerized as long as the effects of the present invention are not impaired.
Olefins such as butene and isobutene, acrylic acid, methacrylic acid, crotonic acid, (phthalic anhydride), (phthalic anhydride)
Unsaturated acids such as maleic acid, (anhydride) itaconic acid or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, N- having 1 to 18 carbon atoms
Acrylamides such as alkylacrylamide, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof;
Methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethyl methacrylamide, 2
Methacrylamides such as methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidopropyldimethylamine or an acid salt or a quaternary salt thereof,
N-vinylpyrrolidone, N-vinylformamide, N-
N-vinylamides such as vinylacetamide, acrylonitrile, vinyl cyanides such as methacrylonitrile,
C1-C18 alkyl vinyl ether, hydroxyalkyl vinyl ether, vinyl ether such as alkoxyalkyl vinyl ether, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl halide such as vinyl bromide, trimethoxy vinyl silane, etc. Vinylsilanes, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3
-Acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropanesulfonic acid and the like.

In the present invention, a single EV as described above is used.
Not only OH but also a composition of two or more EVOHs or a composition of EVOH and another thermoplastic resin can be pelletized. When two or more EVOHs are used,
Although there is no particular limitation, the difference in the degree of saponification is preferably 0.1 to 10 mol% (more preferably 0.3 to 5 mol%). On the other hand, if it exceeds 5 mol%, the compatibility deteriorates, which is not preferable, and the difference in ethylene content is 1%.
If the difference is less than 1 mol%, the effect of improving vacuum formability and stretchability becomes insufficient. On the other hand, if the difference exceeds 30 mol%, compatibility increases. It is not preferable because it worsens, and the difference in MFR is 0 to 60.
g / 10 minutes (more preferably 0 to 50 g / 10 minutes),
If the difference exceeds 60 g / 10 minutes, the dispersibility of the small components deteriorates, which is not preferable.

When EVOH and another thermoplastic resin are used, the thermoplastic resin is not particularly limited, but may be a linear low-density polyethylene, a low-density polyethylene,
Medium density polyethylene, high density polyethylene, ethylene-
Vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-acrylate copolymer, polypropylene, propylene-α-olefin (4-20 carbon atoms α-olefin) copolymer, polybutene, polypentene, etc. Olefin homo- or copolymer,
Or polyolefin resins in a broad sense, such as those obtained by graft-modifying homo- or copolymers of these olefins with unsaturated carboxylic acids or esters thereof, polyesters, polyamides, copolymerized polyamides, polyvinyl chloride, polyvinylidene chloride, acrylic resins , Polystyrene, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, polyketone, polyalcohol, and the like,
Preferably, ionomers, polyamides, polyester elastomers, and polyolefin resins are used.

The mixing ratio (weight ratio) of EVOH and other thermoplastic resin is not particularly limited, either, but EVOH / thermoplastic resin = 99/1 to 40/60 (furthermore, 97/3 to 45
/ 55) is preferable, and when the compounding ratio is less than 99/1, the stretchability, the pinhole resistance and the like become insufficient, and conversely 40%
If it exceeds / 60, the gas barrier properties are undesirably low.

[0010] The present invention relates to an EVOH or an EV as described above.
OH composition (hereinafter collectively referred to as EVOH composition)
Is extruded from a die nozzle into a strand and then cut to produce pellets. The relationship between the shear rate (γ) at the die nozzle and the surface temperature (T) of the EVOH composition at the time of cutting is expressed by the following formula (1). The method is characterized by satisfying, and such a manufacturing method will be described. 1.5 × 10 ³ <(γ · T) <3 × 10 ⁵ (1) where γ is the shear rate (sec ⁻¹ ) and T is the surface temperature (° C.) of EVOH or the EVOH composition, respectively. Represent.

In extruding the EVOH composition from a die nozzle, the EVOH composition is supplied to a melt extruder such as a single screw extruder or a twin screw extruder provided with a die nozzle.
What is necessary is just to extrude the EVOH composition from the die nozzle,
The melting temperature of the melt extruder at this time is preferably 150 to 300 ° C (more preferably 180 to 270 ° C),
If the temperature is lower than 0 ° C., the melting is insufficient and unmelted gel frequently occurs. On the other hand, if the temperature is higher than 300 ° C., the EVOH is undesirably thermally deteriorated and colored. In addition, the screw length L of the extruder
(Mm) and the ratio of the diameter D (mm) of the screw to L
/ D preferably satisfies the relationship of 10 <(L / D) <100, and more preferably 15 <(L / D) <7.
0. If the ratio is less than 10, unmelted gel is frequently generated, and if it exceeds 100, EVOH is thermally deteriorated and colored, which is not preferable.

In the present invention, the shear rate of the EVOH composition in the extruder and the EVO at the time of cutting described later are used.
The relationship with the temperature of the H composition is important, and the shear rate is not particularly limited as long as the relationship is satisfied, but is usually 10 to 10,000 sec ^-1 (furthermore, 50 to 5000 sec).
c- ¹ ), and if the shear rate is too high, pelletization may become difficult because cooling of the strand does not proceed sufficiently. Conversely, if the shear rate is too low, productivity is poor and the output varies. Therefore, the pellet outer diameter fluctuates, which is not preferable. Such a shear rate is generally determined by the discharge amount of the EVOH composition and the shape of the cross section of the die nozzle. For example, when the cross section of the die nozzle is circular, γ =
It can be calculated by 4Q / πr ³ . Where γ
Is the shear rate (sec ^-1 ), Q is the discharge amount of the EVOH composition per die nozzle (cc / sec), and r is the radius of the die nozzle cross section (cm).

Although the shape of the die nozzle is not particularly limited, a circular nozzle having a diameter of 1 to 10 mm is preferable, and a circular nozzle having a diameter of 2 to 7 mm is more preferable in terms of the shape of the pellet. EVO extruded in strand form from die nozzle
The H composition is thereafter cut into pellets. In the present invention, the relationship between the surface temperature T (° C.) of the pellets at the time of cutting and the above-mentioned shear rate γ (sec ⁻¹ ) is determined. , 1.5 × 10 ³ <(γ · T) <3 × 10 ^5, and is obtained when the value of γ · T is 1.5 × 10 ³ or less. When the film is formed with the pellets of the EVOH composition, foaming and rough skin phenomenon occur,
On the other hand, when it exceeds 3 × 10 ⁵ , it becomes difficult to cut the strand, and even when the strand is cut, the shape of the pellet becomes non-uniform. Cannot be achieved, and more preferably 2
× 10 ³ <(γ · T) <2 × 10 ⁵ .

In order to satisfy such conditions, the above-mentioned shear rate and the surface temperature of the EVOH composition may be adjusted, but usually the shear rate is 10 to 1 as described above.
Since it is preferable to be selected from 0000 sec ⁻¹ ,
The temperature is preferably adjusted to about 30 to 150 ° C., and in such adjustment, it is usually preferable to cool the extruded EVOH composition by a method such as air cooling or water cooling, and particularly water cooling in terms of cooling efficiency. Is preferred. In such water cooling, the strand may be cooled in a water tank filled with water at a predetermined temperature. Thus, it is cut into a pellet. The shape of such a pellet is, in the case of a column, a diameter of 1 to 6 mm and a length of 1 to 6 mm.
(More preferably 2-5 mm each) is preferred.

Thus, pellets of the EVOH composition are obtained. The pellets may further contain a lubricant (a lubricant other than those described above), a plasticizer, a heat stabilizer, an ultraviolet absorber, Additives such as inhibitors, colorants, desiccants, oxygen absorbers, antibacterial agents, and fillers, and other resins such as polyolefins and polyamides can also be blended. 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.

Such pellets are formed into films, sheets, containers, fibers, rods, tubes, various molded products, etc. by melt molding or the like, and these pulverized products (for example, when reusing recovered products) are used. It can also be subjected to melt molding again, and as such a melt molding method, an extrusion molding method or an injection molding method is mainly employed. Melt molding temperature is 150 ~ 300 ℃
Often choose from the range. Further, the pellets can be used as a single layer, and it is also useful to laminate a thermoplastic resin layer or the like on at least one surface of a layer composed of the pellets and use it as a multilayer laminate.

In producing the laminate, another substrate is laminated on one side or both sides of the layer composed of the pellets. The lamination method is, for example, that a film or sheet composed of the pellets is coated with a thermoplastic resin. A method of melt-extruding the pellets, a method of melt-extruding the pellets on a base material such as a thermoplastic resin, a method of co-extruding the pellets with another thermoplastic resin, and a pellet obtained by the present invention. A method of dry laminating a film or sheet and a film or sheet of another base material using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester-based compound, or a polyurethane compound may be used.

In the case of coextrusion, the mating resin may be a 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 include polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, polyketone, and polyalcohol. Other EVOH
Can also be coextruded. Among the above, polypropylene, polyamide, polyethylene, ethylene-polyethylene are preferred in view of easiness of coextrusion film formation and practicality of film physical properties (particularly strength).
Vinyl acetate copolymer, polystyrene, PET, and PEN are preferably used.

Further, a molded product such as a film or a sheet is once obtained from the pellets obtained in the present invention, and another substrate is extrusion-coated on this, or a film or sheet of another substrate is formed using an adhesive. When laminating, any substrate (paper, metal foil, uniaxially or biaxially stretched plastic film or sheet, woven fabric, nonwoven fabric, metallic cotton,
Wood, etc.) can be used.

The layer structure of the laminate is such that a layer composed of the pellets obtained in the present invention is a (a ₁ , a ₂ ,...), 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 shape of the laminate thus obtained may be arbitrary, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and an extrudate having a modified cross section. 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, containers and the like obtained as described above are useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

[0022]

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 32 mol%, saponification degree 99.
5 mol%, MFR 3 g / 10 min (210 ° C., load 216
0g)] to a single screw extruder under the following conditions.
H was extruded in a strand shape (3 mm in diameter). [Single screw extrusion conditions] Screw inner diameter 65 mm L / D 32 Screw compression ratio 3.0 die 8-hole strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 180 ° C D: 210 ° C C2: 200 ° C C3: 210 ° C C4: 210 ℃ Shear rate (γ) 440 sec ^-1

Next, the extruded strand of EVOH is water-cooled (passed through a water bath at a water temperature of 30 ° C. at a speed of 0.19 m / sec for 5.2 seconds), and the surface temperature of the EVOH (strand) at the time of cutting (T ) Was adjusted to 80 ° C., cut using a pelletizer, and a 3 mm long, 3 mm diameter EVOH
A pellet was obtained. In the production of such EVOH pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the expression (1) described in the text, γ ·
At T = 3.5 × 10 ⁴ , the expression (1) was satisfied. Using the obtained EVOH pellets, a film was formed for 3 hours under the following conditions, and the torque fluctuation, the discharge amount fluctuation, and the film thickness change were evaluated in the following manner.

[Film forming conditions by single screw extruder] Screw inner diameter 40 mm L / D 28 Screw compression ratio 3.2 T die Coat hanger type Die width 450 mm Extrusion temperature C1: 190 ° C H: 210 ° C C2: 210 ° C D: 210 ° C. C3: 220 ° C. C4: 220 ° C. (Torque fluctuation) Screw torque A when motor load of extruder during continuous film formation (screw rotation speed 60 rpm)
(Amps) is measured continuously and its variation is investigated.
The evaluation was as follows. ○ −−− Fluctuation less than ± 5% △ −−− Fluctuation less than ± 5 ± 10% × −−− Fluctuation more than ± 10%

(Discharge Amount Fluctuation) The discharge amount of EVOH from the extruder during continuous film formation was measured every minute, and the change was examined to evaluate as follows. ○ −−− Fluctuations of less than ± 2% △ −−− Fluctuations of ± 2 to less than ± 5% × −−− Fluctuations of ± 5% or more (Thickness change) Measure the film thickness in the MD direction continuously. The change ratio of the film thickness was determined with the film thickness of 40 μm as the center value, and evaluated as follows. ○ −−− Change ratio of less than ± 5% △ −−− Change ratio of ± 5 to less than ± 10% × −−− Change ratio of ± 10% or more

Example 2 Ethylene content 32 mol%, degree of saponification 99.5 mol%,
E of MFR 3g / 10min (210 ° C, load 2160g)
VOH 65 parts, ethylene content 44 mol%, saponification degree 9
8.5 mol%, MFR 3 g / 10 min (210 ° C., load 2
160 g) of the EVOH composition (35 parts) was supplied to a single screw extruder, and the EVOH composition was extruded into a strand (4 mm in diameter) under the following conditions. [Single screw extrusion conditions] Screw inner diameter 65 mm L / D 32 Screw compression ratio 3 die 8-hole strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 180 ° C D: 210 ° C C2: 200 ° C C3: 210 ° C C4: 210 ° C Shear Speed (γ) 830 sec ^-1

Next, the extruded strands of the EVOH composition were cooled with water (0.36 m / sec in a water bath at a water temperature of 40 ° C.).
At a speed of 1.4 seconds), the surface temperature (T) of the EVOH composition (strand) at the time of cutting was adjusted to 100 ° C., and cut using a pelletizer to obtain a length of 3.0 mm.
An EVOH composition pellet having a diameter of 2.5 mm was obtained. still,
In the production of such EVOH composition pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the expression (1) described in the text, γ · T = 8.3 × 1
0 ⁴ (1) was achieved, thereby satisfying the expression. EV obtained
The OH composition pellets were evaluated in the same manner as in Example 1.

Example 3 Ethylene content 32 mol%, degree of saponification 99.5 mol%,
80 parts of EVOH having an MFR of 3 g / 10 minutes (210 ° C., load of 2160 g) and 20 parts of LLDPE (“Tuffmer PO180” manufactured by Mitsui Chemicals, Inc.) are supplied to a single screw extruder under the following conditions. Was extruded into a strand (diameter 3.0 mm). [Single screw extrusion conditions] Screw inner diameter 40 mm L / D 30 Screw compression ratio 3.0 Die 4-hole strand die Die nozzle 3.0 mm diameter Extrusion temperature C1: 180 ° C D: 210 ° C C2: 200 ° C C3: 210 ° C C4: 210 ℃ Shear rate (γ) 1000 sec ^-1

Next, the extruded strands of the EVOH composition were cooled with water (0.38 m / sec in a water bath at a water temperature of 40 ° C.).
At a speed of 5.3 seconds) to adjust the surface temperature (T) of the EVOH composition (strand) at the time of cutting to 50 ° C., and cut it with a pelletizer to obtain a 3 mm long, 3 mm diameter EVOH. A composition pellet was obtained. In addition, such E
In the production of the VOH composition pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the equation (1) described in the text, the equation (1) was obtained with γ · T = 5 × 10 ^4. Was satisfied. The obtained EVOH composition pellets were evaluated in the same manner as in Example 1.

Example 4 Ethylene content 32 mol%, degree of saponification 99.7 mol%,
E of MFR 4g / 10min (210 ° C, load 2160g)
An EVOH composition comprising 95 parts of VOH and 5 parts of nylon 6.66.610 ("Elvamide 8061" manufactured by Mitsui DuPont) was supplied to a single screw extruder, and the EVOH composition was formed into a strand (diameter: 3.0 mm) under the following conditions. ) Extruded. [Single-screw extrusion condition] Screw inner diameter 40 mm L / D 30 Screw compression ratio 3.5 Die 3 hole strand die Die nozzle 4 mm diameter Extrusion temperature C1: 180 ° C D: 230 ° C C2: 200 ° C C3: 220 ° C C4: 230 ° C Shear Speed (γ) 700 sec ^-1

Next, the extruded strand of the EVOH composition was cooled with water (0.35 m / sec in a water bath at a water temperature of 40 ° C.).
At a speed of 2.9 seconds) to adjust the surface temperature (T) of the EVOH composition (strand) at the time of cutting to 80 ° C.
Cut with a pelletizer, length 3mm, diameter 3m
m of EVOH composition pellets were obtained. In addition, such EVO
In the production of the H composition pellets, the respective values of the shear rate (γ) and the surface temperature (T) are described in (1) in the text.
When substituted into the equation, γ · T = 5.6 × 10 ⁴ and (1)
The expression was satisfied. The obtained EVOH composition pellets were evaluated in the same manner as in Example 1.

Example 5 In Example 1, the extruded strands of the EVOH composition were water-cooled (passed through a water bath at a water temperature of 30 ° C. at a speed of 0.36 m / sec for 0.8 seconds) to obtain a shear rate (γ). ) To 82
EVOH pellets were obtained in the same manner except that the surface temperature (T) was set to 120 ° C. for 5 sec ⁻¹ . In addition, such EV
In the production of OH pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the equation (1) described in the text, the equation (1) was obtained with γ · T = 9.9 × 10 ^4. Was satisfied. The obtained EVOH pellets were evaluated in the same manner as in Example 1.

Example 6 In Example 2, the extruded strands of the EVOH composition were water-cooled (passed through a water bath at a water temperature of 40 ° C. at a speed of 0.44 m / sec for 1.1 seconds) to obtain a shear rate (γ ) To 10
An EVOH composition pellet was obtained in the same manner except that 00 sec ^-1 and the surface temperature (T) were set to 100 ° C. In the production of the EVOH composition pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the expression (1) described in the text, γ · T = 1.0 × 10
⁵ satisfies the expression (1). EVO obtained
The H composition pellets were evaluated in the same manner as in Example 1.

Example 7 In Example 3, the extruded strands of the EVOH composition were water-cooled (passed through a water bath at a water temperature of 40 ° C. at a speed of 0.19 m / sec for 2.7 seconds) to obtain a shear rate (γ). ) To 50
An EVOH composition pellet was obtained in the same manner except that ⁰ sec ⁻¹ and the surface temperature (T) were set to 100 ° C. In the production of the EVOH composition pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the expression (1) described in the text, γ · T = 5 × 10 ⁴ ( 1) The expression was satisfied. The obtained EVOH composition pellets were evaluated in the same manner as in Example 1.

Example 8 In Example 4, the extruded strand of the EVOH composition was water-cooled (passed through a water bath at a water temperature of 40 ° C. at a speed of 0.50 m / sec for 0.5 seconds) to obtain a shear rate (γ). ) To 10
An EVOH composition pellet was obtained in the same manner except that 00 sec ^-1 and the surface temperature (T) were set to 100 ° C. In the production of the EVOH composition pellets, when the respective values of the shear rate (γ) and the surface temperature (T) were substituted into the expression (1) described in the text, γ · T = 1.0 × 10
⁵ satisfies the expression (1). EVO obtained
The H composition pellets were evaluated in the same manner as in Example 1.

Comparative Example 1 In Example 1, the extruded strand of the EVOH composition was water-cooled (passed through a water bath at a water temperature of 5 ° C. at a speed of 0.04 m / sec for 60 seconds), and the surface temperature of the pellet (T ) At 10 ° C. and a shear rate (γ) of 100 sec ⁻¹ to obtain EVOH pellets. In the production of such EVOH pellets, the respective values of the shear rate (γ) and the surface temperature (T) are described in (1) in the text.
When substituted into the equation, γ · T = 1 × 10 ³ , which deviated from equation (1). The obtained EVOH pellets were evaluated in the same manner as in Example 1. In addition to the results shown in Table 2, foaming and perforation were observed in the obtained film.

Comparative Example 2 In Example 1, the extruded strand of the EVOH composition was not water-cooled, and the shear rate (γ) was 3000 sec.
EVOH pellets were obtained in the same manner except that c ^-1 and the pellet surface temperature (T) were 167 ° C. A vermilion (a state not completely separated into individual pellets due to the generation of uncut portions) was observed in the obtained pellets. In the production of such EVOH pellets, the respective values of the shear rate (γ) and the surface temperature (T) are described in (1) in the text.
When substituted into the equation, γ · T = 5 × 10 ⁵ , which deviated from equation (1). The obtained EVOH pellets were evaluated in the same manner as in Example 1. Table 1 summarizes the evaluation results of the examples and comparative examples.

[0038]

[Table 1] Torque variation Discharge volume variation Film thickness variation Example 1 ○ ○ ○ 〃 2 ○ ○ ○ 〃 3 ○ ○ ○ ４ 4 ○ ○ ○ ５ 5 ○ ○ ○ 〃 6 ○ ○ ○ 〃 7 ○ ○ ○ ８ 8 △ ○ ○ Comparative Example 1 × × × 〃 2 × × ×

[0039]

EFFECTS OF THE INVENTION Since the EVOH composition pellets of the present invention are manufactured under specific conditions, they are excellent in feedability to an extruder during melt molding, and have small fluctuations in torque and discharge of the extruder during molding. It is possible to obtain molded products excellent in dimensional accuracy such as shape and thickness, and further, it can be various kinds of laminates, food, pharmaceuticals, agricultural chemicals, films for industrial chemical packaging, sheets, tubes, bottles, Very useful for applications such as cups, bags and containers.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F201 AA10 AC01 AR06 BA02 BC01 BC12 BC17 BC19 BL08 BL29 BL31 BL33 4J002 BB03X BB06X BB12X BB14X BB15X BB17X BB23X BB24X BC03X BD04X BD10X BE02X BE03X BGXX BG02X BG02X CH09X CK02X GG01 GG02

Claims (2)

[Claims] 1. A shear rate at a die nozzle for producing a pellet by extruding a saponified ethylene-vinyl acetate copolymer or a saponified composition of an ethylene-vinyl acetate copolymer from a die nozzle into a strand and cutting the pellet. The relationship between (γ) and the surface temperature (T) of the saponified ethylene-vinyl acetate copolymer or the saponified ethylene-vinyl acetate copolymer composition at the time of cutting satisfies the following formula (1). Method of producing pellets. 1.5 × 10 ³ <(γ · T) <3 × 10 ⁵ (1) [γ is a shear rate (sec ⁻¹ ), and T is a saponified ethylene-vinyl acetate copolymer or ethylene-vinyl acetate. Represents the surface temperature (° C.) of the saponified copolymer composition, respectively] 2. The melt-kneading condition of the saponified ethylene-vinyl acetate copolymer or the saponified ethylene-vinyl acetate copolymer composition supplied to the die nozzle satisfies the following formula (2). A method for producing a pellet according to claim 1. 10 <(L / D) <100 (2) [L is the length of the screw of the extruder used for melt kneading (m
m) and D represent the diameter (mm) of the screw, respectively]