JP2000264972A - Pellet of saponified material of ethylene-vinyl acetate copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject pellets excellent in a field property on their melt molding and capable of providing a formed material having a high dimensional precision such as a shape, thickness, by palletizing an ethylene-vinyl acetate copolymer so as to have a specific resting angle. SOLUTION: The pellets of a saponified material of an ethylene-vinyl acetate copolymer (hereinafter as EVOH) of which resting angle satisfies the condition of formula I, are obtained. It is preferable that the bulk density of the EVOH pellets satisfies the condition of formula II. Such pellets are obtained e.g. by preparing a solution of the EVOH, palletizing it by extruding in a strand state to obtain the EVOH pellets having a specific water content (preferably, finally having 0.01-0.5 wt.% water content) after passing through a drying process and attaching a lubricating agent on the surfaces of the pellets. The obtained EVOH pellets can be used as a film, sheet, container, or the like, by melt molding, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pellets of saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH), and more particularly to feedability during melt molding (removability of resin into an extruder). The present invention relates to an EVOH pellet which is excellent in (1), has little torque fluctuation and discharge fluctuation of the extruder during molding, and has extremely good dimensional accuracy of the obtained molded product.

[0002]

2. Description of the Related Art In general, EVOH is excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance, etc., and by utilizing such characteristics, food packaging material, pharmaceutical packaging material, industrial chemical packaging. 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, EVOH pellets are usually fed into an extruder or the like, and are molded into a film or sheet by melt molding.
Depending on the properties of the H pellet, a 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.
Japanese Patent Publication No. 47-38634 discloses that a methanol-water mixed solution of EVOH is extruded into water or a methanol-water mixed solution at a temperature of 50 ° C. or lower in the form of a strand and precipitated.
A method for obtaining VOH pellets is disclosed in JP-A-53-9898, in which an EVOH solution is discharged from the pores of a die into water or a mixture of methanol and water, and immediately thereafter separated by a cutter to obtain a spherical shape. A method for obtaining EVOH pellets is disclosed in Japanese Patent Application Laid-Open No. 53-120767.
A method of feeding an H solution strand to a cutting section through a specific introduction pipe to obtain an EVOH pellet is disclosed in
No. 06904 discloses that an EVOH solution containing a lubricant is extruded into a coagulating liquid in the form of a strand, and then cut into a solid form.
As a method for obtaining VOH pellets, Japanese Patent Application Laid-Open No. 3-61507 describes a method for introducing EV strands into a cutting section by using a belt conveyor and cutting while spraying water to obtain EVOH pellets. .

[0004]

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.

[0005]

Accordingly, the present inventors have conducted intensive studies in view of the present situation, and as a result, have found that there is a relationship between the angle of repose of EVOH pellets and the above-mentioned problem. It was completed. That is, they have found that an EVOH pellet having a repose angle (RA) satisfying the following condition (1) can achieve the above object. 30 ° ≦ RA ≦ 45 ° (1) Further, when the bulk density (BD) of the EVOH pellet satisfies the condition of the following formula (2), the effect of the present invention can be remarkably obtained. It is. 0.6 ≦ BD ≦ 0.8 (g / cc) (2)

[0006] The angle of repose here means the angle between the generatrix of the cone and the horizontal plane when the EVOH pellets are dropped onto a plane from a funnel or the like and deposited in a cone shape.
Specifically, a horizontally placed glass container (inner size: 9.5 cm in diameter, 2 cm in height) is placed 10 cm from the top of the container.
EVOH through a glass funnel with a foot diameter of 8 mm from the height of
The pellet is allowed to fall freely until it overflows from the container, and the height (Hcm) of the peak of the resulting cone-shaped EVOH pellet having the horizontal surface on the upper surface of the container as the base is measured, and is calculated by the following equation (3). The measurement is performed three times, and the average value is defined as the angle of repose (RA). Angle of repose (BD) (゜) = Arctan (H / 4.75) (3) where Arctan represents an arctangent function.

[0007] The bulk density (BD) refers to a value obtained by dividing the weight that can fill an EVOH pellet into a predetermined volume by the volume. Specifically, the volume is 400 cc (inner size: 7.4 cm in diameter, The EVOH pellets are freely dropped from a height of 10 cm from the upper surface of the cup to a metal cup (weight xg) having a height of 9.3 cm (cylindrical shape) with a foot diameter of 8 mm. EV overflowing above
The OH pellet is removed flat along the edge, and the total weight (yg) of the metal cup and the EVOH pellet filled in the cup is measured, and is calculated by the following equation (4). Is performed three times, and the average value is taken as the bulk density (B
D). Bulk density (g / cc) = (y−x) / 400 (4)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The EVOH used as a raw material for the EVOH pellets of the present invention is not particularly limited, but has an ethylene content of 20 to 60.
Mol% (more preferably 25 to 55 mol%) and a saponification degree of 90 mol% or more (more preferably 95 mol% or more) are used,
If the ethylene content is less than 20 mol%, the gas barrier properties and the melt moldability at high humidity decrease, while if it exceeds 60 mol%, sufficient gas barrier properties cannot be obtained, and the saponification degree is 90%.
If it is less than mol%, the gas barrier properties, thermal stability, moisture resistance, etc. decrease, which is not preferred. Further, the melt index (MI) (210 ° C., load 2160 g) of the EVOH is 0.1.
1 to 100 g / 10 min (further 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 to make extrusion difficult, and if the melt index is larger than the above range, the mechanical strength of the molded product will be high. Is insufficient and is not preferred. The EVOH is obtained by saponifying an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer is produced by any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization and the like. The saponification of the ethylene-vinyl acetate copolymer can also be carried out 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. 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 (anhydride) maleic acid and (anhydride) itaconic acid or salts thereof, mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, 1 to 1 carbon atoms
8, acrylamides such as N-alkylacrylamide, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof, methacrylamide, having 1 to 18 carbon atoms Methacrylamides such as N-alkylmethacrylamide, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidopropyldimethylamine or an acid salt thereof or a quaternary salt thereof, N-vinylpyrrolidone , N-vinylformamide, N-vinylamides such as 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 and vinyl bromide And vinylsilanes such as trimethoxyvinylsilane, allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl)-
Ammonium chloride, acrylamido-2-methylpropanesulfonic acid and the like.

[0010] The EVOH pellets of the present invention are obtained from the EVOH as described above.
It is necessary that the angle of repose (RA) of the EVOH pellets satisfies the condition of the above formula (1), and if the condition is not satisfied, it is difficult to achieve the object of the present invention. That is, when the angle of repose of the EVOH pellets is smaller than 30 ° or larger than 45 °, the feedability at the time of melt molding becomes uneven, and the object of the present invention cannot be achieved. The range of the angle of repose is more preferably 30 to 40 °, particularly preferably 32 to 3 °.
7 °. Although there is no particular limitation for satisfying the angle of repose, (1) the pellet shape is cylindrical (1 to 6 m in diameter).
m, length 1-6 mm), (2) uniform size distribution of pellets (both in diameter and length, the ratio of pellets having an average size within ± 5% is 95% by weight or more), (3) pellets And (4) uniformly attaching a specific amount of an emulsion-type lubricant to the surface of the pellets.

That is, when EVOH is pelletized, usually, the EVOH solution is extruded into a coagulating liquid in the form of a strand to be coagulated, then cut into pellets, and then washed with water as necessary. In the pelletizing step, the concentration of the EVOH solution, the temperature at the time of extrusion of the EVOH solution, the type of the solvent of the EVOH solution, the type of the coagulation liquid, the temperature of the coagulation liquid, the coagulation liquid Residence time of EVOH strands, amount of carboxylic acid in coagulating solution, amount of carboxylic acid metal salt, amount of carboxylic acid ester, weight ratio of coagulating solution to EVOH strand, strand diameter and EVOH after cutting
The length of the pellets, furthermore, in the water washing step, the temperature of the washing water, the washing time, the weight ratio of the washing water to the EVOH pellets, and the temperature of the heating gas in the drying step,
Moisture percentage of heating gas, linear velocity and flow rate of heating gas, presence and degree of agitation and flow during drying, and type of lubricant, properties of lubricant, amount of adhesion, rate of addition of lubricant to EVOH in lubricant adhesion process The EVOH pellets of the present invention can be obtained by arbitrarily adjusting the above.

In particular, among these, the weight ratio of the coagulating liquid and the EVOH strand in the pelletizing step (coagulating liquid /
EVOH strand) of 50 to 10000,
1 to 10,000 ppm of carboxylic acid in the coagulation liquid and / or
Or 1 to 15000 ppm of a metal carboxylate and / or 1 to 50,000 ppm of a carboxylic acid ester; the property of the lubricant in the step of attaching the lubricant is an emulsion type; and the rate of addition of the lubricant (solid content) to 100 parts by weight of EVOH. Is set to 0.001 to 1 part by weight / hr, and the attached amount is set to 10 to 1000 ppm, so that the desired EVOH pellets as described in the above (1) to (4) can be suitably obtained. is there.

Further, in the present invention, the bulk density (BD) of the EVOH pellets preferably satisfies the condition of the above formula (2), and the bulk density is less than 0.6 (g / cc) and 0.8 or less. If it exceeds (g / cc), the feedability at the time of melt molding tends to become more nonuniform, which is not preferable. In order to adjust the bulk density, in addition to the methods (1) to (4) for satisfying the angle of repose described above, (5) the number of irregularly shaped pellets is further reduced (crack, chipping, crushing, twisting, melting). (The ratio of the attached pellets is 1% or less). That is, EVOH pellets satisfying the above bulk density may be obtained by the above-described methods (1) to (4), but in order to surely obtain EVOH pellets satisfying the bulk density, (5) It is preferred to carry out the method of the above), specifically, to carry out the stationary drying treatment after the fluidized drying treatment in the drying step, and to set the heating gas linear velocity in the fluidized dryer to 0.7 to 1
0 m / sec and the heating gas linear velocity in the stationary dryer is 1 m
/ Sec, a more preferable EVOH pellet satisfying the bulk density can be obtained.

The method for obtaining the EVOH pellet of the present invention will be described in detail. When EVOH is made into a solution, it may be dissolved in a solvent in which EVOH can be dissolved, and the solvent and method are not limited. Examples of the solvent include methanol, ethanol, propanol, phenol, and dimethyl sulfoxide ( Solvents such as DMSO), dimethylformamide (DMF), and hexafluoroisopropanol (HFIP), and an aqueous solution (mixed solvent) containing these solvents. 80/20 to 5/95 and the alcohol content A (% by weight) is 2.5%
5E-40.75 ≦ A ≦ 2.55E-15.75 (where E is the ethylene content (mol%) of EVOH)
Is preferably satisfied, and the amount of EVOH contained in the solution is preferably 20 to 55% by weight (more preferably 25 to 50% by weight). As a method for preparing the solution, a) dissolving powder or pellets of EVOH to a predetermined concentration in a solvent or a mixed solvent of solvent / water, or b) saponifying treatment during EVOH production After EVOH
A) adding a proper amount of a solvent, water or a mixed solvent thereof to the solvent solution of the above, or c) depositing or depositing the EVOH during production of the EVOH; For example, a method of dissolving the composition to obtain a liquid composition may be mentioned, and the method (b) may be suitably used for production.

Next, the EVOH solution obtained above is extruded into a strand and pelletized. Such a solution may be used as it is, or the solution may be appropriately concentrated or diluted, or water may be added. It is also possible to prepare a solution for strand production. At this point, saturated aliphatic amides (e.g., stearic acid amide, etc.), unsaturated fatty acid amides (e.g., oleic acid amide, etc.), bis fatty acid amides
(E.g., ethylene bisstearic acid amide, etc.), fatty acid metal salt (e.g., calcium stearate, etc.), low molecular weight polyolefin (e.g., low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene, etc.)
Lubricants, inorganic salts (such as hydrotalcite, etc.),
Plasticizers (for example, aliphatic polyhydric alcohols such as ethylene glycol, glycerin, hexanediol and the like), antioxidants, ultraviolet absorbers, coloring agents, antibacterial agents, antiblocking agents, slip agents and the like may be added.

Examples of the coagulating liquid to be precipitated include water or a mixed solvent of water / alcohol, aromatic hydrocarbons such as benzene, ketones such as acetone and methyl ethyl ketone, ethers such as dipropyl ether, methyl acetate, ethyl acetate and propionic acid. Organic acid esters such as methyl are used, but water or a mixed solvent of water / alcohol is preferred. As the alcohol, alcohols such as methanol, ethanol, and propanol are used, and preferably, methanol is used.

The weight ratio of the coagulating liquid to the EVOH strand (coagulating liquid / EVOH strand) in the coagulating liquid is preferably 50 to 10,000, and more preferably 1 to 10,000.
00 to 1000. By setting the weight ratio in the above range, the size distribution is uniform (the average size is ± 5 for both diameter and length).
% Of the pellets is 95% by weight or more, and 97% or more.
(% By weight or more) of EVOH pellets. Further, a carboxylic acid is added to the coagulating liquid in an amount of 1 to 10,000 p.
pm and / or metal carboxylate from 1 to 15000
ppm and / or carboxylic acid ester from 1 to 500
It is preferred that the carboxylic acid be contained in an amount of 50 ppm to 5000 ppm and / or 10 to 5000 ppm of a metal carboxylate and / or 10 to 10000 ppm of a carboxylic acid ester. By containing the carboxylic acids in the above range in the coagulation bath, it is possible to more suitably obtain EVOH pellets having a uniform size distribution.

The carboxylic acid is not particularly restricted but includes formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, crotonic acid,
Maleic acid, itaconic acid and the like can be mentioned, but acetic acid is preferably used. Such a metal carboxylate is not particularly limited, but sodium formate, potassium formate, magnesium formate, calcium formate, sodium acetate, potassium acetate, magnesium acetate, and the like are used, and preferably, sodium acetate is used. Such carboxylic acid esters are not particularly limited, but methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl acetoacetate, ethyl acetoacetate, and the like are used. Preferably, methyl acetate is used.

The temperature at which the EVOH solution is brought into contact with the coagulating liquid is preferably from -10 to 40 ° C, more preferably from 0 to 20 ° C.
Particularly, it is 0 to 10 ° C. Since the above-mentioned organic solvent is a non-solvent for the saponified product, there is almost no fear that the EVOH dissolves in the coagulating liquid and causes resin loss, but operation at a low temperature is safe as much as possible. The EVOH solution is extruded in the form of a strand into the coagulating liquid as described above by a nozzle having an arbitrary shape. The shape of the nozzle is not particularly limited, but a cylindrical shape is preferable, and the length is 1 mm. ~ 1
00 cm is preferred, more preferably 3 to 30 cm, and the inner diameter is preferably 0.1 to 10 cm, more preferably 0.2 to 5.0 c
m.

Thus, the EVOH (solution) is extruded from the nozzle in the form of a strand. The number of strands is not necessarily one, and any number between several and several hundreds can be extruded. Next, the EVOH extruded into strands is cut after the coagulation has sufficiently proceeded,
It is pelletized and then washed with water. The shape of such a pellet is 1 to 6 mm in diameter and 1 to 6 mm in length when it is cylindrical.
(More preferably 2 to 5 mm each), and in the case of a spherical shape, those having a diameter of 1 to 6 mm (more preferably 2 to 5 mm) are preferable. As for the washing condition, the pellets are washed in a water bath at a temperature of 10 to 40C (further 20 to 40C). Such washing with water removes oligomers and impurities in the EVOH.

Next, after the above-mentioned pelletization, a drying step is performed to obtain EVOH pellets having a specific water content. As such a drying method, various drying methods can be adopted, but in the present invention, it is preferable to carry out fluidized drying, and it is particularly preferable to carry out static drying after fluidized drying. The method will be described.

Fluid drying referred to herein is substantially equivalent to EVO.
H means that drying is performed while the pellets are stirred or dispersed mechanically or by hot air. The drying device for performing the drying includes a cylindrical / groove type stirring dryer, a cylindrical dryer, a rotary dryer, and a fluidized bed dryer. Oven, vibrating fluidized bed dryer, conical rotary dryer and the like.
VOH pellets mean drying that is performed without being subjected to dynamic actions such as stirring and dispersion. As a dryer for performing the drying, a batch box type dryer is used as a material stationary type, and a material transfer type is used. Examples thereof include, but are not limited to, a band dryer, a tunnel dryer, and a vertical silo dryer.

Air or an inert gas (nitrogen gas, helium gas, argon gas, etc.) is used as a heating gas used in the fluidized drying treatment, and the temperature of the heating gas is preferably 40 to 95 ° C., and more preferably 40 to 95 ° C. Is 60-90 ° C
Is preferred. The moisture content of the heating gas is preferably 0.5 to 2.5% by weight (more preferably 0.5 to 2.0% by weight). Further, the velocity of the heated gas in the dryer is
It is preferably 0.7 to 10 m / sec, more preferably 0.7 to 5.0 m / sec, particularly 1.0 to 3.0 m / sec.
sec is preferable, and if the speed is less than 0.7 m / sec, fusion of the EVOH pellets is likely to occur.
If it exceeds m / sec, the EVOH pellets are liable to crack, chip, etc., which is not preferable. In addition, the time for fluidized drying depends on the processing amount of the EVOH pellets, but is usually preferably 5 minutes to 36 hours, and more preferably 10 minutes to 24 hours.

The EVOH pellets are subjected to fluid drying under the above-mentioned conditions, and the water content of the EVOH pellets after the treatment is preferably 5.0 to 60% by weight (more preferably 10 to 55% by weight). If the water content is less than 5.0% by weight, the ejection fluctuation is likely to occur when the EVOH pellets obtained after the standing drying treatment are melt-molded, and conversely, when the EVOH pellets are formed in a melt-molded state, the EVOH pellets have a water content of 6%.
If the content exceeds 0% by weight, fusion of the EVOH pellets tends to occur during the subsequent standing drying treatment, which is not preferable. Also,
In such a fluidized drying treatment, it is preferable to lower the water content by 5.0% by weight or more (more preferably 10 to 45% by weight) than before the treatment, and even when the reduction of the water content is less than 5.0% by weight. However, it is not preferable because the EVOH pellets are likely to be fused during the subsequent (static) drying treatment.

The EVOH pellets subjected to the fluid drying treatment as described above are then subjected to a static drying treatment.
Similarly, an inert gas (nitrogen gas, helium gas, argon gas, etc.) is used as the heating gas used for the stationary drying process, and the temperature of the heating gas is preferably 75 ° C. or higher, and more preferably 85 to 150 ° C. If the temperature is lower than 75 ° C., the drying time must be extremely long, which is economically disadvantageous and is not preferred. The moisture content of the heating gas is 0.5 to 2.5% by weight (further, 0.5 to 2.5% by weight).
To 2.0% by weight).

Further, the velocity of the gas in the dryer is 1.0 m / s.
ec, and more preferably 0.01 to 0.
The speed is preferably 5 m / sec, and if the speed exceeds 1 m / sec, it becomes difficult to keep the EVOH pellets in a stationary state, which is not preferable. In addition, the time for the stationary drying process is also EV
Although it cannot be said unconditionally depending on the treatment amount of the OH pellet, it is usually preferably 10 minutes to 72 hours, more preferably 1.0 to 48 hours. Under the above conditions, the EVOH pellets are subjected to standing drying treatment to obtain finally dried EVOH pellets. The moisture content of the EVOH pellets after the treatment is 0.01 to 0.5% by weight (further, (0.02 to 0.4% by weight), and the water content is 0.1%.
If the amount is less than 01% by weight or more than 0.5% by weight, the adhesion of the lubricant tends to be uneven, which is not preferable. Then, after the above-mentioned drying treatment, the obtained EVOH having a specific moisture content is obtained.
By attaching a lubricant to the surface of the pellet, the target EVOH pellet can be obtained.

Examples of the type of the lubricant include higher fatty acids (eg, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), metal salts of higher fatty acids (the above-mentioned aluminum salts, calcium salts of higher fatty acids,
Zinc salts, magnesium salts, barium salts, etc.), higher fatty acid esters (methyl ester, isopropyl ester, butyl ester, octyl ester, etc. of the aforementioned higher fatty acids), higher fatty acid amides (stearic acid amide, behenic acid amide, etc.) Amide, oleic acid amide,
Unsaturated fatty acid amides such as erucamide, ethylenebisstearic acid amide, ethylenebisoleic acid amide,
Bis fatty acid amides such as ethylene bis erucamide and ethylene bis lauric amide), low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000 or low molecular weight polypropylene, or acid-modified products thereof), higher alcohols , Ester oligomers, fluorinated ethylene resins and the like, preferably higher fatty acids and / or metal salts, esters and amides thereof, and more preferably higher fatty acid metal salts and / or higher fatty acid amides.

As the properties of the lubricant, any properties such as solid (powder, fine powder, flake, etc.), semi-solid, liquid, paste, solution, emulsion (aqueous dispersion) are used. Although it is possible, in order to efficiently obtain the EVOH pellets aimed at by the present invention, those in the form of emulsion are preferred.

As a method of adhering such a lubricant to the surface of EVOH pellets, a method of blending the lubricant with EVOH using a blender or the like is used.
A method of mixing and attaching the pellets, a method of immersing the EVOH pellets in a lubricant solution or dispersion and attaching them, a method of spraying and attaching the lubricant solution or dispersion to the EVOH pellets, and the like are preferable. The EVOH pellets are charged into a blender or the like, and the emulsion-like lubricant is mixed with stirring and the solid content of the lubricant is set to 0.001 to 1 part by weight / hr, and further to 0.01 to 0 part by weight based on 100 parts by weight of the EVOH pellets. It is preferable to gradually add the lubricant at a rate of 0.1 parts by weight / hr for uniform adhesion of the lubricant. The amount of the lubricant to be attached is 10 to 1000 ppm with respect to the EVOH pellets, and further 20 to 500 ppm.
However, it is preferable in that the feedability at the time of melt molding is stabilized.

Thus, the EVOH pellets of the present invention are obtained. If necessary, the EVOH pellets may further contain a lubricant (a lubricant other than the above), a plasticizer,
Additives such as heat stabilizers, ultraviolet absorbers, antioxidants, coloring agents, drying agents, oxygen absorbers, antibacterial agents, 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.

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 that differs by mol% or more, since the stretchability during high stretching and the secondary workability such as vacuum pressure forming and deep drawing can be improved while maintaining gas barrier properties. The EVOH pellets thus obtained are formed into films, sheets, containers, fibers, rods, pipes, various molded products, etc. by melt molding or the like, and these pulverized products (for example, when reusing recovered products) are used. It can be used again for melt molding, 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. In addition, EVOH pellets obtained in the present invention are:
It can be used as a single layer, or it is also useful to laminate a thermoplastic resin layer or the like on at least one surface of a layer composed of EVOH pellets and use it as a multilayer laminate.

In producing the laminate, the EV
The other substrate is laminated on one or both sides of the layer composed of the OH pellets.
A method of melt-extruding a thermoplastic resin into a film or sheet made of H pellets, and conversely, a method of applying the EV to a base material such as a thermoplastic resin.
A method of melt-extruding OH pellets, a method of co-extrusion of the EVOH pellets with another thermoplastic resin, and a film or sheet of EVOH pellets obtained by the present invention and a film or sheet of another base material. Organic titanium compounds,
A dry lamination method using a known adhesive such as an isocyanate compound, a polyester-based compound, or a polyurethane compound may, for example, be mentioned.

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 polybutene and polypentene, and 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 EVOH pellets obtained in the present invention, and another substrate is extrusion-coated on the molded product, or a film or sheet of the other substrate is formed by using an adhesive. In the case of lamination, 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 that of the EV obtained in the present invention.
A (a)₁, A_Two,···),other
B (b)₁, B_Two, ...
・), If it is a film, sheet or bottle
For example, not only the two-layer structure of a / b, but also b / a / b, a / b
/ A, a₁/ A_Two/ B, a / b₁/ B_Two, B_Two/ B₁/ A / b
₁/ B_TwoAny combination is possible, such as filament
In the shape, a and b are bimetal type, core (a) -sheath (b) type,
Any combination such as core (b) -sheath (a) type or eccentric core-sheath type
Matching is possible.

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

[0037]

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 12 g / 10 min (210 ° C., load 216
0 g)] water / methanol (water / methanol = 40/6)
0 mixture weight ratio) mixed solution (EVOH concentration 40%)
At a rate of kg / hour, a coagulation bath containing 5 ppm of acetic acid and 50% of methanol and 95% of water is extruded in a strand form from a cylindrical nozzle into a coagulation bath maintained at 5 ° C. and taken off at the end of the coagulation bath. After being brought into contact with the coagulation bath by a roller for 60 seconds, the strand was drawn out of the coagulation bath. The weight ratio of the coagulating solution to the EVOH strand in the coagulating bath (coagulating solution) was 1,000. Next, the strand was cut with a cutter to have a diameter of 3.8 mm and a length of 4 mm.
mm white porous pellets were obtained. Next, the pellet was washed with warm water at 30 ° C. to obtain a porous pellet having a water content of 56%.

Further, the porous pellets were subjected to nitrogen gas at a temperature of 75 ° C. for 2 m / sec in a batch column type fluidized bed dryer.
After passing through at a linear velocity of 3.5 and drying for 3.5 hours to a water content of 20%, using a batch-type ventilation box type dryer,
0.3 g of nitrogen gas having a temperature of 125 ° C. and a moisture content of 0.5%
The mixture was passed at a linear speed of m / sec and dried for 18 hours to obtain dry EVOH pellets having a moisture content of 0.3%. The dimensions of the obtained pellets are cylindrical with a diameter of 2.8 mm and a length of 2.9 mm, and the size distribution is uniform (the ratio of pellets with an average size within ± 5% for both diameter and length is 98%). Yes, the proportion of irregularly shaped pellets was 0.05%.

Next, 100 kg of the pellets were placed in a cylindrical blender, and the mixture was adjusted to a lubricant [“Alflow H-50E” manufactured by NOF Corporation, an aqueous dispersion of ethylenebisstearic acid amide, and a solid content of 20%. Use]
Was continuously added at a rate of 200 g / hr for 30 minutes.
After completion of the addition, stirring was continued for 30 minutes to obtain EVOH pellets of the present invention having a lubricant adhesion of 200 ppm.
The angle of repose and the bulk density of the EVOH pellets measured by the methods described in the text were 33 ° and 0.67 cc / g, respectively. 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 using 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) The screw torque A (ampere) at the time of the motor load (screw rotation speed 60 rpm) of the extruder during the continuous film formation was continuously measured, and the fluctuation was examined to evaluate 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 fluctuation was examined to evaluate as follows. ○ −−− Fluctuation of less than ± 2% △ −−− Fluctuation of ± 2 to less than ± 5% × −−− Fluctuation of ± 5% or more

(Change in Film Thickness) The thickness of the film in the MD direction was continuously measured, and 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 EVOH [ethylene content 42 mol%, saponification degree 99.
6 mol%, MI 8.0 g / 10 min (210 ° C., load 21
60 g)] water / methanol (water / methanol = 25 /
75 mixed weight ratio) 1 mixed solution (EVOH concentration 36%)
At a rate of 0 kg / hour, the mixture was extruded in a strand form from a cylindrical nozzle into a coagulation bath maintained at 5 ° C., comprising 5% of methanol containing 100 ppm of sodium acetate and 95% of water, and attached to the end of the coagulation bath. After being brought into contact with the coagulation bath by a take-off roller for 80 seconds, the strand was drawn out of the coagulation bath. The weight ratio of the coagulation solution and the EVOH strand in the coagulation bath (coagulation solution) was 1,100.
Next, the strand was cut with a cutter to give a diameter of 3.
A white porous pellet having a length of 8 mm and a length of 4.0 mm was obtained. Next, the pellet was washed with warm water at 30 ° C. to obtain a porous pellet having a water content of 60%.

Further, the porous pellets were passed through a continuous horizontal multi-chamber fluidized bed drier at a temperature of 75.degree.
After passing through at a linear speed of / sec and drying for 4 hours to obtain a water content of 25%, using a batch-type ventilation box type dryer, nitrogen gas at a temperature of 125 ° C and a linear speed of 0.3 m / sec. And dried for 20 hours to obtain a water content of 0.25%
Of dried EVOH pellets. The dimensions of the obtained pellets are cylindrical with a diameter of 2.7 mm and a length of 2.8 mm, and the size distribution is uniform (98% of the pellets have an average size within ± 5% for both diameter and length). Yes, the proportion of irregularly shaped pellets was 0.04%.

Next, 100 kg of the pellets were placed in a cylindrical blender, and the mixture was adjusted to a lubricant [“Alflow H-50E” manufactured by NOF Corporation, an aqueous dispersion of ethylenebisstearic acid amide, and a solid content of 20%] with stirring. Use]
Was added continuously at a rate of 180 g / hr for 25 minutes.
After completion of the addition, stirring was continued for 30 minutes to obtain EVOH pellets of the present invention having a lubricant adhesion amount of 150 ppm.
The angle of repose and the bulk density of the EVOH pellets were 34 ° and 0.69 cc / g, respectively, as measured by the methods described in the text. The obtained EVOH pellets were evaluated in the same manner as in Example 1.

Example 3 EVOH [Ethylene content 30 mol%, saponification degree 99.
6 mol%, MI 8.1 g / 10 min (210 ° C., load 21
60 g)] water / methanol (water / methanol = 60 /
40 mixed weight ratio) 1 mixed solution (EVOH concentration 36%)
At a rate of 0 kg / hr, a cylindrical nozzle extrudes a strand from a cylindrical nozzle into a coagulation bath maintained at 3 ° C., comprising 4% of methanol containing 50 ppm of methyl acetate and 96% of water.
By the take-off roller attached to the end of the coagulation bath,
After contacting the coagulation bath for 120 seconds, the strand was pulled out of the coagulation bath. Coagulation liquid in coagulation bath (coagulation liquid) and E
The weight ratio of the strands of VOH was 1100. Next, the strand was cut with a cutter to obtain a diameter of 4.2 m.
m, 4.5 mm long white porous pellets were obtained.
Next, the pellet was washed with warm water at 30 ° C. to obtain a porous pellet having a water content of 59%.

Further, the porous pellet was subjected to nitrogen gas at a temperature of 80 ° C. for 2.0 m / s in a batch column type fluidized bed dryer.
After passing through at a linear speed of ec and drying for 3 hours to obtain a water content of 30%, a batch-type rotary dryer was used to obtain a temperature of 1%.
A dry EV having a moisture content of 0.3% was dried by passing nitrogen gas at 25 ° C. at a linear velocity of 0.08 m / sec for 22 hours.
OH pellets were obtained. The dimensions of the obtained pellets are cylindrical with a diameter of 3.2 mm and a length of 3.4 mm, and the size distribution is uniform (98% of the pellets have an average size within ± 5% for both diameter and length). Yes, the proportion of irregularly shaped pellets was 0.07%.

Next, 100 kg of the pellets were put into a cylindrical blender, and the mixture was adjusted to a lubricant [“Alflow H-50E” manufactured by NOF Corporation, an aqueous dispersion of ethylenebisstearic acid amide, and a solid content of 15%] with stirring. Use]
Was continuously added at a rate of 200 g / hr for 30 minutes.
After completion of the addition, stirring was continued for 30 minutes to obtain EVOH pellets of the present invention having a lubricant adhesion amount of 150 ppm.
The angle of repose and the bulk density of the EVOH pellets were 34 ° and 0.71 cc / g, respectively, as measured by the methods described in the text. The obtained EVOH pellets were evaluated in the same manner as in Example 1.

Example 4 In Example 1, the obtained dried EV having a moisture content of 0.3% was obtained.
Put 100 kg of OH pellets in a cylindrical blender,
While stirring, the lubricant [Chukyo Yushi "Hydrin Z-7"
-30 ", aqueous dispersion of zinc stearate, solid content 20%
Used at a rate of 200 g / hr.
Added for 0 minutes. After the addition was completed, stirring was continued for 30 minutes, and the same operation was performed except that the amount of the attached lubricant was 200 ppm, and the angle of repose and the bulk density were 36 ° and 0.6%, respectively.
7 cc / g EVOH pellets were obtained. EVO obtained
The H pellet was evaluated in the same manner as in Example 1.

Example 5 In Example 2, the obtained dried E having a moisture content of 0.25% was obtained.
100 kg of VOH pellets are put into a cylindrical blender, and while stirring, a lubricant [Cerosol 9 manufactured by Chukyo Yushi Co., Ltd.
20 ", an aqueous dispersion of stearic acid, solid content 18%]
It was added continuously at a rate of 80 g / hr for 25 minutes. Stirring was continued for 30 minutes after the addition was completed, so that the amount of the attached lubricant was 1
EVOH with a repose angle and a bulk density of 38 ° and 0.69 cc / g, respectively, except that the concentration was 50 ppm.
A pellet was obtained. About the obtained EVOH pellet,
Evaluation was performed in the same manner as in Example 1.

Comparative Example 1 EVOH [Ethylene content 35 mol%, saponification degree 99.
5 mol%, MI 12 g / 10 min (210 ° C., load 216
0 g)] water / methanol (water / methanol = 60/4)
0 mixture weight ratio) mixed solution (EVOH concentration 40%)
At a rate of kg / hour, a coagulation bath is extruded in a strand form from a cylindrical nozzle into a coagulation bath maintained at 25 ° C. comprising 5% of methanol and 95% of water, and is taken up by a take-off roller attached to an end of the coagulation bath. After 10 minutes of contact in the strands, the strand was withdrawn from the coagulation bath. Next, the strand was cut with a cutter to obtain white porous EVOH pellets having a diameter of 3.8 mm and a length of 4 mm. Next, the pellet was washed with warm water at 50 ° C. to obtain a porous pellet having a water content of 56%.

Further, the porous pellets were passed through a batch-type ventilation box-type dryer through a nitrogen gas at a temperature of 70.degree.
Dried EVOH pellets having a moisture content of 0.3% were dried for 18 hours with nitrogen gas at a temperature of 120 ° C. using a batch column type fluidized bed dryer after drying for 35 hours to obtain a moisture content of 35%. I got The angle of repose and the bulk density of the EVOH pellets were 46 ° and 0.59 g / cc, respectively, as measured by the methods described in the text. EV obtained
The OH pellets were evaluated in the same manner as in Example 1.

Comparative Example 2 In Example 1, the obtained dried EV having a water content of 0.3% was obtained.
Put 100 kg of OH pellets in a cylindrical blender,
While stirring, the lubricant [Alflo H-5 manufactured by NOF Corporation
0T ", fine powder of ethylenebisstearic acid amide] 1
20 g was added all at once, and stirring was continued for 30 minutes to obtain EVOH pellets having a lubricant adhesion of 1200 ppm.
The angle of repose and the bulk density of the EVOH pellets were 28 ° and 0.66 g / cc, respectively, as measured by the methods described in the text. 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.

[0056]

[Table 1]

[0057]

Since the EVOH pellets of the present invention have a specific angle of repose, they are excellent in feedability to the extruder during melt molding, have little fluctuation in torque and discharge of the extruder during molding, and have a small shape and thickness. A molded product with excellent dimensional accuracy can be obtained, and further, it can be made into various kinds of laminates, and films, sheets, and the like for packaging foods, pharmaceuticals, agricultural chemicals, and industrial chemicals.
It is very useful for applications such as tubes, bottles, cups, bags, and containers.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 29:04 F term (Reference) 4F070 AA26 AA28 DA05 DA32 DA48 DA55 DB07 DC07 DC08 DC09 4F201 AA04E AA19E AC01 AG01 AR15 AR20 BA02 BC02 BC12 BC19 BC29 BD05 BL12 BL42 BL43 4J100 AA02P AG04Q BA03H CA04 HA08

Claims (4)

[Claims] 1. A saponified ethylene-vinyl acetate copolymer pellet having a repose angle (RA) satisfying the following condition (1). 30 ° ≦ RA ≦ 45 ° (1) 2. Saponified ethylene-vinyl acetate copolymer pellets, wherein the angle of repose (RA) satisfies the condition of the following formula (1 ′). 30 ° ≦ RA ≦ 40 ° (1 ′) 3. Saponified ethylene-vinyl acetate copolymer pellets having an angle of repose (RA) satisfying the following formula (1 ″). 32 ° ≦ RA ≦ 37 ° (1 ″) 4. The saponified ethylene-vinyl acetate copolymer pellet according to claim 1, wherein the bulk density (BD) satisfies the condition of the following formula (2). 0.6 ≦ BD ≦ 0.8 (g / cc) (2)