JP2003276021A - Method for manufacturing saponified ethylene-vinyl acetate copolymer composition pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing saponified ethylene-vinyl acetate copolymer composition pellets in which break of strands is suppressed, and the diametrically-stable pellets having no cavities, uncolored and suitable for obtaining molded products excellent in appearance where gel is suppressed and dimensional stability is provided. <P>SOLUTION: When the composition mainly containing the saponified ethylene- vinyl acetate copolymer is melted with an extruder to manufacture the pellets, following conditions (1) to (4), and further (1) to (5), are satisfied: (1) a ratio (L/D) of the extruder screw length L (mm) to a screw diameter D (mm) is 10 to 70; (2) a specific energy E (kWh/kg) in melt extrusion is 0.1 to 0.5; (3) a discharge quantity q (kg/h) per each die nozzle is 5 to 20; (4) a temperature T(°C) of the molding resin is from a melting point of the saponified ethylene- vinyl acetate copolymer composition to the melting point + 70(°C); and (5) a relation among a discharge quantity Q (kg/h) of the extruder, the screw diameter D (mm), and the number of the revolutions N (rpm) of the screw is -5<ln(Q /DN)<-3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a pellet of a composition containing a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH), and more specifically to suppressing strand breakage during pellet production. TECHNICAL FIELD The present invention relates to a method for producing EVOH composition pellets, which is useful for obtaining a molded product which has no voids, has a stable diameter and is free of coloration, and has excellent appearance with suppressed gel.

[0002]

2. Description of the Related Art Generally, EVOH is excellent in its transparency, gas barrier property, aroma retaining property, solvent resistance, oil resistance, etc., and taking advantage of such characteristics, it is used for food packaging materials, pharmaceutical packaging materials, industrial chemical packaging. It is used by being formed into films and sheets such as materials and agricultural chemical packaging materials, or containers such as bottles and cups. However, although EVOH has the above-mentioned characteristics, it may not be able to sufficiently satisfy the required performance in terms of mechanical properties and secondary workability (stretchability, vacuum formability, hollow formability, etc.).
Blending of two or more kinds of EVOH and blending other thermoplastic resins such as polyolefin resins and polyamide resins are routinely performed.

The above-mentioned blending is carried out by supplying a resin to be blended to a single-screw or twin-screw melt extruder and melt-kneading the mixture, and then extruding it into a strand shape and cutting it into pellets. Is common. The blend thus obtained (EVO
H composition) pellets are subjected to various moldings, but depending on the above-mentioned pelletization conditions (molding of pellets), a good molded product may not be finally obtained,
The extrusion conditions of the melt extruder at the time of pelletizing are also important. For example, JP-A-8-165397, JP-A-9-40825, JP-A-11-58500 and the like have a stipulation of specific energy at the time of extrusion of an extruder, and JP-A-11-106590. Etc. also has a description of specific energy.

[0004]

However, when the present inventor examined the specific energy, it was found that the control of only the specific energy does not necessarily give EVOH composition pellets excellent in moldability. . That is, voids may occur in the pellet cross section, or variations in the pellet outer diameter may occur, causing air entrapment during melt kneading in the former case, and in the latter case, deterioration of feedability and deterioration of moldability may occur. There is. Further, if the discharge speed of the resin composition is increased in order to improve the pelletization efficiency, sland breakage may occur, and further improvement is desired.

[0005]

Therefore, in view of the present situation, the present inventor has considered the screw outer diameter D (m of the extruder.
m), screw length L (mm), screw rotation speed N
(Rpm), discharge amount per die nozzle q (kg /
h), as a result of intensive studies on control of the resin temperature T (° C.) and the like, as a result of melting a composition containing EVOH using an extruder to produce pellets, the following (1) to (4) By performing under the conditions of, it is possible to suppress strand breakage during pellet production, there is no void, pellets with stable diameter and without coloring can be efficiently obtained, and gel-suppressed molded articles with excellent appearance are obtained. Useful for E
It was found that a VOH composition pellet was obtained, and the present invention was completed. (1) The ratio (L / D) of the screw length L (mm) of the extruder and the screw outer diameter D (mm) is set in the range of 10 to 70. (2) Specific energy E (kWh / kg) during melt extrusion Is set in the range of 0.1 to 0.5 (3) The discharge amount q (kg / h) per die nozzle is set in the range of 5 to 20 (4) The resin temperature T (° C) is set to the melting point of EVOH to Melting point +70
(° C) range

In the present invention, by further satisfying the following condition (5), it is possible to obtain the effect of the present invention remarkably. (5) The relationship between the discharge rate Q (kg / h) of the extruder, the screw outer diameter D (mm), and the rotation speed N (rpm) is -5 <l.
n (Q / DN) <-3

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The EVOH used in the present invention is not particularly limited, but has an ethylene content of 20 to 60 mol% (further 25
.About.55 mol%, particularly 25 to 50 mol%), and a saponification degree of 90 mol% or more (further 95 mol% or more, especially 96 mol% or more) are used, and the ethylene content is 20.
If it is less than mol%, the gas barrier properties at high humidity and melt moldability will be deteriorated. On the contrary, if it exceeds 60 mol%, sufficient gas barrier properties will not be obtained, and if the saponification degree is less than 90 mol%, gas barrier properties and heat stability will be obtained. Properties and humidity resistance are unfavorably deteriorated.

The melt flow rate (MFR) of the EVOH (210 ° C., load 2160 g) is 0.1-0.1%.
100 g / 10 minutes (further 0.5 to 50 g / 10 minutes, particularly 1 to 40 g / 10 minutes) is preferable, and when the MFR is smaller than the range, the inside of the extruder is in a high torque state during molding. Therefore, the extrusion process becomes difficult, and if it exceeds the above range, the mechanical strength of the molded product becomes insufficient, which is not preferable.

The EVOH is obtained by saponification of an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer can be obtained by any known polymerization method such as solution polymerization,
It is produced by suspension polymerization, emulsion polymerization or the like, and saponification of an ethylene-vinyl acetate copolymer can be performed by a known method.

Further, in the present invention, an ethylenically unsaturated monomer which can be copolymerized may be copolymerized within a range that does not impair the effects of the present invention. Examples of such a monomer include propylene and 1-butene. , Olefins such as isobutene, acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid,
Unsaturated acids such as (anhydrous) maleic acid and (anhydrous) itaconic acid or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, 1 to 1 carbon atoms
8, N-alkylacrylamide, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof, methacrylamide, methacrylamide, and 1 to 18 carbon atoms. N-alkylmethacrylamide, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidopropyldimethylamine or its acid salt or its quaternary salt, and other N-vinylpyrrolidone. N-vinylamides such as N-vinylformamide and N-vinylacetamide,
Vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide. Vinyl halides such as trimethoxyvinylsilane, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl)-
Examples thereof include ammonium chloride and acrylamido-2-methylpropanesulfonic acid.

In the present invention, the resin blended with the above EVOH is not particularly limited, and the above EVO
EVOH different from H or other thermoplastic resin may be used.
When making a blend of two or more kinds of EVOH, EVOH having different at least one of the saponification degree, the ethylene content, the MFR and the like can be blended.

The thermoplastic resin when EVOH and another thermoplastic resin are used is not particularly limited, but may be linear low density polyethylene, low density polyethylene,
Medium density polyethylene, high density polyethylene, ethylene-
Vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, etc. Olefin homo- or copolymer,
Alternatively, polyolefin resins in a broad sense such as those obtained by graft-modifying homo- or copolymers of these olefins with unsaturated carboxylic acids or their esters, polyesters, polyamides, copolyamides, polyvinyl chloride, polyvinylidene chloride, acrylic resins , Polystyrene, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, polyketone, polyalcohol, etc.,
Preferable are polyolefin resins such as ethylene-vinyl acetate copolymers, ionomers, ethylene-α olefin copolymers and acid-modified products thereof, polyamide resins (6 nylon, 6,66 nylon, 6,12 nylon etc.), A polyester elastomer is used.

Further, in the blending, besides the above-mentioned thermoplastic resin, an antioxidant, a lubricant, an antiblocking agent, a plasticizer, which is used for improving the physical properties of EVOH, etc.
Additives such as heat stabilizers, ultraviolet absorbers, colorants, desiccants, oxygen absorbers, antibacterial agents, and fillers can also be added.

There is no particular limitation on the blending ratio between EVOHs or a blend of EVOH and another resin, and the blending ratio may be appropriately determined according to the application and purpose of the composition. Sometimes other EVOH is 3 to 97% by weight (even 5 to 95% by weight,
7 to 93% by weight, especially 10 to 90% by weight), EV
When blending OH and other resin, for example EVOH and polyolefin resin or polyamide resin, the other resin
-60 wt% (further 5-55 wt%, especially 7-5
0% by weight, especially 10 to 45% by weight),
The effects of the present invention can be obtained more effectively.

The method of the present invention will be described in more detail below. In the present invention, using an extruder, the following (1)
The greatest feature is that the EVOH composition is pelletized so as to satisfy the conditions (4) to (4), and further the conditions (1) to (5). The extruder is not particularly limited. Generally, a single-screw or multi-screw extruder is used, and a single-screw and a twin-screw are preferably used. (1) The ratio (L / D) of the screw length L (mm) of the extruder and the screw outer diameter D (mm) is set in the range of 10 to 70. (2) Specific energy E (kWh / kg) during melt extrusion Is set in the range of 0.1 to 0.5 (3) The discharge rate q (kg / h) per die nozzle is set in the range of 5 to 20 (4) The resin temperature T (° C) is set to the melting point of EVOH to Melting point +70
(5) The relationship between the discharge amount Q (kg / h) of the extruder, the screw outer diameter D (mm), and the rotation speed N (rpm) of the extruder is set to -5 <l.
n (Q / DN) <-3

First, in order to satisfy the condition (1), the ratio (L / D) of the screw length L (mm) and the screw outer diameter D (mm) of the extruder is 10 to 70 (further, 15).
To 65, especially 20 to 60, and especially 25 to 55), and if the ratio is less than 10, melt-kneading cannot be sufficiently performed, while if it exceeds 70, the composition is thermally deteriorated and colored. Therefore, the object of the present invention cannot be achieved.

Further, the specific energy E (kWh / kg) at the time of melt extrusion in the above (2) is 0.1 to 0.5 (further 0.11 to 0.49, particularly 0.12 to 0.48). , Especially 0.15 to 0.45), and even if the specific energy E is less than 0.1, melt kneading cannot be sufficiently performed,
On the other hand, when it exceeds 0.5, the composition deteriorates due to heat and causes coloration, or the molded product of the obtained pellets frequently has fish eyes, and the object of the present invention cannot be achieved.

In adjusting the specific energy E, it is possible to control by the extruder diameter, L / D, screw configuration, temperature setting, screw rotation speed, discharge amount, etc. It is preferable that the above condition (5) is satisfied, and further, -4.9 <ln (Q / DN) <-3.1, particularly -4.8 <ln (Q / DN) <-. It is preferable to satisfy the condition of 3.2, and the value of such ln (Q / DN) is −
If it is less than 5, the composition may be deteriorated by heat.
If it exceeds 3, unmelting may occur, which is not preferable.

Further, as in the above (3), the discharge rate q (kg / h) per die nozzle is set to 3 to 30 (further 4 to 25, particularly 5 to 20, particularly 7 to 15). When the discharge amount q is less than 5, the extrusion of the strands becomes unstable and uniform strands cannot be obtained. On the other hand, when the discharge amount exceeds 20, the cooling in the cooling water tank becomes insufficient and cutting is performed. Cannot be achieved, or the strand is unstable and the caliber is not stable, so that the object of the present invention cannot be achieved.

The melting point of EVOH to melting point +70 (° C.) [further melting point +5 (° C.) to melting point +65 (° C.), especially melting point +10, as defined by the resin temperature T of (4).
(° C.) to melting point +60 (° C.), particularly melting point +15 (° C.) to melting point +55 (° C.)], and when the temperature T is lower than the melting point of EVOH, it becomes unmelted, and conversely melting point +70
If it exceeds (° C.), the object of the present invention cannot be achieved due to thermal deterioration. In addition, when there are two or more types of EVOH,
Based on highest melting point.

In the present invention, the above (1) to (4) are used.
Alternatively, the EVO should satisfy the conditions (1) to (5).
It suffices to pelletize the H composition, and the pellet manufacturing method will be described more specifically. First, in selecting a single-screw or twin-screw extruder, the screw length L and the screw outer diameter D may be set so that the above condition (1) is satisfied. Usually, L is 200 to 5000 mm. (Further 250-4000 mm, especially 600-3500 m
m) is preferred and L is 200
If it is less than mm, the resin to be blended may be insufficiently dispersed, and if it exceeds 5,000 mm, EVOH may deteriorate, which is not preferable. Also, D is 20 to 200
mm (further 25-180 mm, especially 30-150 mm
mm), and D is 20
If it is less than mm, the extrusion rate is low and the productivity is poor.
If it exceeds m, shear heat generation increases and thermal deterioration may occur, which is not preferable.

Then, in the hopper of the extruder as described above,
A mixture obtained by dry-blending EVOH and another resin (or another EVOH) or the like at a desired mixing ratio is charged, and melt-kneading is started. The resin temperature of the mixture at this time is set so as to satisfy the above (4). The temperature of each cylinder is not particularly limited as long as it is set so as to satisfy the above formula (4), but normally the cylinder temperature is supplied (melted).
The melting point of EVOH is 1 to 150 ° C (further 3 to
If the temperature is set higher than 100 ° C. and the temperature is lower than the melting point, the melting becomes insufficient, the motor load becomes large, and the extrusion becomes difficult.
If the temperature is higher than 0 ° C, EVOH is thermally deteriorated, which is not preferable.

In such melt-kneading, it is necessary to make the specific energy E of the extruder at the time of melt-kneading satisfy the above (2). Here, the specific energy E is the amount of power consumption used for kneading the extruder divided by the kneading amount per hour, and the kneading amount (discharge amount) of the EVOH composition and the extruder motor. It suffices to adjust the power consumption (current × voltage) of the above so as to fall within the range of (2) above. However, in the present invention, it is preferable to adjust so as to satisfy the condition of (5). . That is, the discharge amount Q and the screw rotation speed N are controlled so as to satisfy the above condition (2).
Fine adjustment may be performed so as to satisfy the condition (5).

The number of rotations N of the screw is not particularly limited as long as it is set so as to satisfy the above expression (5), but usually 10 to 1000 rpm (further 20 to 80 rpm).
It is preferable to select from the range of 0 rpm, especially 30 to 500 rpm). When the rotation speed is less than 10 rpm, a sufficient extrusion amount cannot be obtained, and when it exceeds 1000 rpm, a sufficient residence time cannot be obtained and unmelted. It is not preferable because it causes poor mixing.

The EVOH composition melt-kneaded under the above-mentioned conditions is finally extruded in a strand form from a die nozzle and then cut to obtain the desired EVOH composition pellets. In the present invention,
It is necessary to make the discharge amount q per one die nozzle satisfy the above condition (3). Specifically,
The number of holes of the die nozzle can be selected in consideration of the total discharge amount Q of the EVOH composition.

Thus, the EVOH composition in the form of a strand extruded from the die nozzle as described above is cut by a pelletizer or the like to obtain the desired EVOH composition pellets.

The shape of the pellet is preferably 1 to 6 mm in diameter and 1 to 6 mm in length (further, 1.5 to 5 mm, respectively) when it is cylindrical.

The EVOH composition pellets obtained by the method of the present invention are formed into films, sheets, containers, fibers, rods, pipes, various molded products, etc. by melt molding, and crushed products (collected) When the product is reused), it can be subjected to melt molding again, and as such a melt molding method, an extrusion molding method and an injection molding method are mainly adopted.
The melt molding temperature is often selected from the range of 150 to 300 ° C. Further, the pellets can be used as a single layer, or it is also useful to laminate a layer made of the pellets with a thermoplastic resin layer or the like on at least one surface to be used as a multilayer laminate.

In producing the laminate, another base material is laminated on one or both sides of the layer made of the pellets. The lamination method is, for example, a film or sheet made of the pellets and a thermoplastic resin. Melt extrusion, conversely a method of melt extruding the pellets into a substrate such as a thermoplastic resin, a method of co-extruding the pellets with another thermoplastic resin, further comprising the pellets obtained in the present invention Examples thereof include a method of dry laminating a film or sheet with a film or sheet of another base material using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound.

In the case of coextrusion, the other resin is linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene. -Acrylic ester copolymer, polypropylene, propylene-α-olefin (having 4 to 20 carbon atoms)
Α-olefin) copolymer, polybutene, homopolymer or copolymer of olefin such as polypentene, or a polyolefin in a broad sense such as homo- or copolymer of these olefins graft-modified with unsaturated carboxylic acid or its ester Resin, polyester, polyamide, copolyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene, vinyl ester resin,
Examples thereof include polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, polyketone, polyalcohol and the like. Other EVOH
Can be coextruded. Among the above, polypropylene, polyamide, polyethylene, and ethylene-polyethylene are preferable from the viewpoint of ease 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 sheet is once obtained from the pellets obtained in the present invention, and another substrate is extrusion coated on the molded product, or a film or sheet of another substrate is adhesively used. In the case of laminating by using any of the above-mentioned thermoplastic resins, any base material (paper, metal foil, uniaxially or biaxially stretched plastic film or sheet, woven cloth, non-woven cloth, metallic cotton shape,
Wood, etc.) can be used.

The layer structure of the laminate is a (a1, a2, ...), which is a layer made of pellets obtained by the present invention, and b (b1, b2 ,.・ ・)
When it is a film, sheet, or bottle,
Not only the two-layer structure of / b, but also b / a / b, a / b / a,
a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b
Any combination such as 1 / b2 is possible, and in the filament form, a and b are bimetal type, core (a) -sheath (b)
Mold, core (b) -sheath (a) type, eccentric core-sheath type or the like can be arbitrarily combined.

The shape of the laminate thus obtained may be arbitrary, and examples thereof include films, sheets, tapes, bottles, pipes, filaments and modified cross-section extrudates. In addition, the obtained laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry laminating treatment,
Solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing and the like can be performed. The film, sheet or container obtained as described above is useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

[0034]

EXAMPLES 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 3g / 10 minutes (210 ° C, load 216
0 g), melting point 182 ° C.] 65 parts and EVOH [ethylene content 44 mol%, saponification degree 98 mol%, MFR 3 g / 1
0 minutes (210 ° C, load 2160g), melting point 158 ° C] 3
5 parts were fed to a single-screw extruder, and the EVOH composition was formed into a strand (the inner diameter of the die nozzle was 4.5 mm) under the following conditions.
Extruded into.

[Single-screw Extrusion Condition] Screw outer diameter D 65 mm Screw length L 2340 mm L / D 36 Discharge rate Q 132 kg / h Screw rotation speed N 110 rpm Discharge rate per nozzle 1 hole q 9.4 kg / h Die 14-hole strand die Die nozzle diameter 4.5 mm Extrusion temperature C1: 210 ° C. D: 210 ° C. C2: 210 ° C. C: 205 ° C. C: 210 ° C. Specific energy E 0.34 kWh / kg In the above extrusion conditions, ln (132/65.
110) = − 4.0, which satisfied the condition (5) in the text. Further, in the above, although stranding was continuously performed for 72 hours, strand breakage did not occur and good strands were obtained.

Then, the extruded EVOH composition strand was water-cooled (water temperature 30 ° C.) and cut using a pelletizer to obtain a cylindrical EVOH composition pellet having a length of about 3 mm.

The EVOH composition pellets thus obtained were evaluated in the following manner. (Cavity in pellet cross section) The presence or absence of a cavity in the pellet cross section and its size were observed by a loupe and evaluated as follows. ○: No void △: Less than 0.2 mm ×: 0.2 mm or more

(Outer Diameter of Pellet) The major axis (larger diameter) of the obtained pellet was measured with a caliper and evaluated as follows. A: The ratio of 1.8 to 2.8 mm is 100%. The ratio of 1.8 to 2.8 mm is 90 to less than 100%. The ratio of 1.8 to 2.8 mm is 90. %Less than

(Coloring of Pellet) Y of the obtained pellet
The I (yellow index) value was measured and evaluated as follows. ○: YI value is less than 15 Δ: YI value is less than 15 to 20 × ... YI value is 20 or more

Next, using the obtained pellets, film formation was performed for 3 hours under the following conditions, and the thickness of the obtained film in the MD direction at the center was measured at 1 m intervals over 10 m. Thickness-minimum thickness) / average thickness was calculated, and the variation in thickness was evaluated as described later.

[0042] [Film forming conditions with a single screw extruder]     Screw inner diameter 40 mm     L / D 28     Screw compression ratio 3.2     T-die coat hanger type     Die width 450mm     Extrusion temperature C1: 190 ° C H: 210 ° C                         C2: 210 ° C D: 210 ° C                         C3: 220 ° C                         C4: 220 ° C

(Variation in thickness) ◎ ... 0.1 or less ○: over 0.1 and below 0.2 X ... exceeds 0.2

Example 2 EVOH [ethylene content 32 mol%, saponification degree 99.
5 mol%, MFR 3.2 g / 10 minutes (210 ° C., load 2
160 g), melting point 182 ° C.] 80 parts and ultra-low density polyethylene (“Tufmer A4085” manufactured by Mitsui Chemicals, Inc., density of 0.
20 parts of 88 g / cm ³ ) was supplied to a single-screw extruder, and the EVOH composition was extruded in a strand shape (inner diameter of die nozzle was 4.0 mm) under the following conditions.

[Single-screw Extrusion Condition] Screw outer diameter D 65 mm Screw length L 2340 mm L / D 36 Discharge rate Q 170 kg / h Screw rotation speed N 130 rpm Discharge rate per nozzle 1 hole q 12.1 kg / h Die 14-hole strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 210 ° C. D: 210 ° C. C2: 210 ° C. C: 205 ° C. C4: 210 ° C. Specific energy E 0.35 kWh / kg In the above extrusion conditions, ln (170/65.
130) = − 3.9, which satisfies the condition (5) in the text. Further, in the above, although stranding was continuously performed for 72 hours, strand breakage did not occur and good strands were obtained.

Then, the extruded EVOH composition strand was water-cooled (water temperature 30 ° C.) and cut using a pelletizer to obtain a cylindrical EVOH composition pellet having a length of about 3 mm. The EVOH composition pellets obtained were evaluated in the same manner as in Example 1.

Example 3 EVOH [ethylene content 32 mol%, saponification degree 99.
7 mol%, MFR 3.4 g / 10 min (210 ° C, load 2
160 g), melting point 182 ° C.] 85 parts and polyamide resin (“Novamid 1022” manufactured by Mitsubishi Engineering Plastics, 6 nylon) 15 parts are fed to a single-screw extruder, and the EVOH composition is formed into a strand under the following conditions. (The inner diameter of the die nozzle was 4.0 mm).

[Single-screw extrusion conditions] Screw outer diameter D 65 mm Screw length L 2340 mm L / D 36 Discharge rate Q 170 kg / h Screw rotation speed (N) 130 rpm Discharge rate q per nozzle q 8.1 kg / h Die 21 holes Strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 210 ° C. D: 210 ° C. C2: 210 ° C. C: 205 ° C. C: 210 ° C. Specific energy E 0.38 kWh / kg In addition, under the above extrusion conditions, ln (170/65・
130) = − 3.9, which satisfies the condition (5) in the text. Further, in the above, although stranding was continuously performed for 72 hours, strand breakage did not occur and good strands were obtained.

Next, the extruded EVOH composition strand was water-cooled (water temperature 30 ° C.) and cut using a pelletizer to obtain a cylindrical EVOH composition pellet having a length of about 3 mm. The EVOH composition pellets obtained were evaluated in the same manner as in Example 1.

Example 4 EVOH [ethylene content 32 mol%, saponification degree 99.
5 mol%, MFR 3.5 g / 10 minutes (210 ° C., load 2
160 g), melting point 182 ° C.] and 15 parts of polyamide resin (“Mrill Japan CF6S”, 6,12)
Nylon) (15 parts) was supplied to a single-screw extruder, and the EVOH composition was extruded into a strand shape (inner diameter of die nozzle was 3 mm) under the following conditions.

[Single-screw extrusion condition] Screw outer diameter D 65 mm Screw length L 2340 mm L / D 36 Discharge rate Q 170 kg / h Screw rotation speed N 130 rpm Discharge rate per nozzle 1 hole q 14.2 kg / h Die 12-hole strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 210 ° C. D: 210 ° C. C2: 210 ° C. C: 205 ° C. C4: 210 ° C. Specific energy E 0.40 kWh / kg In addition, under the above extrusion conditions, ln (170/65.
130) = − 3.9, which satisfies the condition (5) in the text. In the above, although stranding was continuously performed for 72 hours, strand breakage did not occur and good strands were obtained.

Then, the extruded EVOH composition strand was water-cooled (water temperature 30 ° C.) and cut using a pelletizer to obtain a cylindrical EVOH composition pellet having a length of about 3 mm. The EVOH composition pellets obtained were evaluated in the same manner as in Example 1.

Example 5 EVOH [ethylene content 32 mol%, degree of saponification 99.
5 mol%, MFR 3.2 g / 10 minutes (210 ° C., load 2
160 g), melting point 182 ° C.] 90 parts, and saturated polyester (“Polyester SP154” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., density g / cm ³ ) 10 parts were supplied to a single-screw extruder, and an EVOH composition was prepared under the following conditions. It was extruded in a strand shape (inner diameter of die nozzle was 3 mm).

[Single screw extrusion condition] Screw outer diameter D 65 mm Screw length L 2340 mm L / D 36 Discharge rate Q 85 kg / h Screw rotation speed (N) 100 rpm Discharge rate per nozzle 1 hole q 10.6 kg / h Die 8 holes Strand die Die nozzle 3.5 mm diameter Extrusion temperature C1: 210 ° C. D: 210 ° C. C2: 210 ° C. C: 205 ° C. C: 210 ° C. Specific energy E 0.37 kWh / kg In the above extrusion conditions, ln (85/65・ 1
00) = − 4.4, which satisfies the condition (5) in the text. In the above, stranding was continuously performed for 72 hours, but strand breakage did not occur,
Good strands were obtained.

Next, the extruded EVOH composition strands were water-cooled (water temperature 30 ° C.) and cut with a pelletizer to obtain cylindrical EVOH composition pellets having a length of about 3 mm. The EVOH composition pellets obtained were evaluated in the same manner as in Example 1.

Comparative Example 1 An EVOH composition pellet was produced in the same manner as in Example 1 except that the L / D under the single-screw extrusion condition was set to 8. However, strand breakage occurred during production of the strand. The production of EVOH composition pellets was discontinued.

Comparative Example 2 EVOH composition pellets were produced in the same manner as in Example 1 except that the L / D of the single-screw extrusion condition was set to 80, and the same evaluation was performed.

Comparative Example 3 In Example 1, the screw shape was changed (compression ratio to 1.0) and the specific energy was 0.08 kWh / k.
Although EVOH composition pellets were tried to be produced in the same manner except that the amount was changed to g, the production of EVOH composition pellets was stopped because strand breakage occurred during the production of strands.

Comparative Example 4 EVOH composition pellets were produced in the same manner as in Example 1 except that the screw shape was changed (compression ratio to 5.0) so that the specific energy became 0.6 kWh / kg. Then, the same evaluation was performed.

Comparative Example 5 EVOH composition pellets were produced in the same manner as in Example 1, except that the number of strand nozzles was 33 and the discharge rate per die nozzle was 4 kg / h. It evaluated similarly.

Comparative Example 6 EVOH composition pellets were produced in the same manner as in Example 1 except that the number of strand nozzles was 6 and the discharge rate per die nozzle was 22 kg / h. Was evaluated.

Comparative Example 7 EVOH composition pellets were produced in the same manner as in Example 1 except that the melting temperature was changed to 270 ° C., and the same evaluation was performed. The evaluation results of Examples and Comparative Examples are summarized in Table 1.

[Table 1] Hollow section hollow cavity Outer diameter of pellets Color variation of pellet Example 1 ○ ○ ○ ○ 〃 2 ○ ○ ○ ○ 〃 3 ○ ○ ○ ○ 〃 4 ○ ○ ○ ○ 〃 5 ○ ○ ○ ○ Comparative Example 1 Discontinuation due to strand breakage 〃 2 ○ ○ × ○ 〃 3 Discontinuation due to strand break 〃 4 ○ × ○ × 〃 5 ○ × ○ × 〃 6 × ○ × ○ 〃 7 × ○ × ○

[0064]

EFFECTS OF THE INVENTION According to the method of the present invention, strand breakage during the production of pellets can be suppressed, and pellets having no voids and having a stable diameter and without coloring can be efficiently obtained, and the appearance and the appearance of the gel can be suppressed. EVOH composition pellets useful for obtaining a molded article having excellent dimensional stability can be obtained, and by using such pellets, a molded article such as a film having excellent accuracy with little thickness variation and no coloring can be obtained. It can also be made into various laminated products, such as films, sheets, tubes for packaging foods, pharmaceuticals, agricultural chemicals, and industrial chemicals.
Very useful for applications such as bowls, cups, bags, and containers.

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Claims (3)

[Claims] 1. A method of melting a composition containing a saponified product of an ethylene-vinyl acetate copolymer using an extruder to produce pellets is performed under the following conditions (1) to (4). And a method for producing saponified ethylene-vinyl acetate copolymer composition pellets. (1) The ratio (L / D) of the screw length L (mm) of the extruder and the screw outer diameter D (mm) is set in the range of 10 to 70. (2) Specific energy E (kWh / kg) during melt extrusion Is in the range of 0.1 to 0.5 (3) The discharge rate q (kg / h) per die nozzle is in the range of 5 to 20 (4) The resin temperature T (° C) is ethylene-vinyl acetate The melting point of the saponified copolymer to the melting point +70 (° C) is set. 2. The method for producing saponified ethylene-vinyl acetate copolymer pellets according to claim 1, which further satisfies the following condition (5). (5) The relationship between the discharge rate Q (kg / h) of the extruder, the screw outer diameter D (mm), and the rotation speed N (rpm) is -5 <l.
n (Q / DN) <-3 3. A composition comprising two or more kinds of saponified ethylene-vinyl acetate copolymer saponified products, a composition of saponified ethylene-vinyl acetate copolymer and polyolefin resin, and ethylene-vinyl acetate copolymer saponified composition. 3. The method for producing pellets of saponified ethylene-vinyl acetate copolymer composition according to claim 1 or 2, which is a composition of a compound and a polyamide resin.