JP6809179B2 - Ethylene-vinyl ester copolymer saponified pellets and molding materials - Google Patents

Description

The present invention relates to an ethylene-vinyl ester-based copolymer saponified product (hereinafter, may be referred to as “EVOH resin”) pellet group and molding material, and more specifically, an EVOH resin pellet group and molding material having good handleability. Regarding.

The EVOH resin has high crystallinity due to hydrogen bonds between hydroxyl groups existing in the polymer side chain, and further has high intermolecular force even in the amorphous portion. Based on such a structure, the film using EVOH resin exhibits excellent gas barrier properties.

Due to its excellent gas barrier property, EVOH resin is used by molding it into films and sheets such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, agricultural chemical packaging materials, and containers such as bottles. The EVOH resin used as such a molding material is generally distributed as pellets having a length of about 1 to 10 mm.

EVOH resin pellets are generally produced by a method called a strand cut method. In the strand cut method, for example, as disclosed in Japanese Patent Application Laid-Open No. 3-61507 (Patent Document 1), a solution obtained by dissolving an EVOH resin (or a composition thereof) in an appropriate solvent is prepared with a diameter of 1 to 1. A rod-shaped strand obtained by extruding a resin having a hole of about 5 mm into a coagulating liquid or extruding a heat-melted resin into a die and cooling and solidifying the resin is cut into a certain size using a cutter. This is a method for producing cylindrical EVOH resin pellets.

As a method for solving a manufacturing problem of the strand cut method (difficulty in cutting a large amount of resin in a short time with high dimensional accuracy), for example, Japanese Patent Application Laid-Open No. 2001-96530 (Patent Document 2) is disclosed. It has been proposed to cut the water-containing and molten EVOH resin immediately after discharge from the extruder (hot cut method). Such a hot-cut method includes an aerial-cut method of cutting by rotating a rotary blade immediately after extruding a water-containing molten EVOH resin discharged from a discharge port of a twin-screw extruder; cooling water of the EVOH resin from the extruder. There is an underwater cutting method in which the resin is discharged into a cutter box filled with the above and cut in water immediately after the discharge. It is described that a flat spherical EVOH resin pellet was obtained by the underwater cutting method. However, the degree of flatness was as small as 0.79 with respect to the diameter, which was close to a sphere.

In general, spherical pellets have higher fluidity and tend to have a smaller angle of repose than cylindrical pellets, and molding is easy to stabilize. In recent years, spherical pellets have tended to increase from cylindrical pellets. ..

As a method for producing spherical pellets having a uniform pellet shape and size by cutting a solution of EVOH resin instead of cutting the melted EVOH resin, for example, Japanese Patent Application Laid-Open No. 2006-524144 (Patent Document 3) It is disclosed. Examples of the pellet shape include a spherical shape, an oval shape, an elliptical shape, and a water droplet shape. However, all of the illustrated pellets have a shape that easily rotates around the major axis.

As a method for improving feed stability during molding by combining a spherical pellet and a cylindrical pellet as described above, for example, Japanese Patent Application Laid-Open No. 2015-155104 (Patent Document 4) is disclosed, and further specific It has been described that the pellet group having an angle of repose has excellent feed stability.

JP-A-3-61507 Japanese Unexamined Patent Publication No. 2001-96530 Special Table 2006-524144 JP-A-2015-155104

The cylindrical pellet produced by the production method of Patent Document 1 has a problem that the fluidity as a pellet group is low, the ejection stability at the time of molding tends to be low, and the film thickness of the film fluctuates.
The spherical pellets produced by the methods of Patent Documents 2 to 4 and the mixture of the spherical and cylindrical pellets have good fluidity as a pellet group, and have good processing stability during molding, but have good fluidity. If it is too large, it may fall off due to unexpected flow during transportation or storage of pellets. There was a tendency for the stagnation to spread over a wide area, and for the handling to be poor.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an EVOH resin pellet group having excellent feedability and an EVOH resin pellet group having good handleability as a molding material. To provide.

The present inventor has made various studies focusing on the production method and shape of EVOH resin pellets, and arrived at the present invention.
That is, the gist of the present invention lies in the pellet group of EVOH resin pellets, in which at least 50% of the pellets in the pellet group have a friction angle of 20 to 40 ° with respect to the stainless steel plate. The present invention also provides a molding material composed of the EVOH resin pellet group.

The pellet group and the molding material of the present invention are excellent in feedability, low self-fluidity, do not spread over a wide range even if they fall off, and are excellent in handleability.

Hereinafter, the configuration of the present invention will be described in detail, but these are examples of desirable embodiments and are not specified in these contents.

The pellet group of the present invention is composed of ethylene-vinyl ester copolymer saponified (EVOH resin) pellets, and the pellet group is usually composed of EVOH resin pellets having a substantially circular or elliptical cross section.

First, the EVOH resin, which is a constituent material of the pellets contained in the pellet group, will be described.
<EVOH resin>
The ethylene-vinyl ester-based copolymer saponified product (EVOH resin) used for the pellets included in the pellet group of the present invention is usually obtained by copolymerizing ethylene and a vinyl ester-based monomer and then saponifying them. It is a resin and is a water-insoluble thermoplastic resin.
Generally, vinyl acetate is generally used as the vinyl ester-based monomer from the economical point of view. The polymerization method may be any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization, and solution polymerization using methanol as a solvent is generally used. Further, it may be either a continuous type or a batch type.
As a method for introducing ethylene into the copolymer, ordinary ethylene pressure polymerization may be performed. The content of ethylene units can be controlled by the pressure of ethylene and is usually selected from the range of 25-80 kg / cm ² according to the desired ethylene content.

The obtained ethylene-vinyl ester copolymer can also be saponified by a known method. Such saponification can be carried out using an alkali catalyst or an acid catalyst in a state where the copolymer obtained above is dissolved in an alcohol or a hydrous alcohol.
The EVOH resin synthesized as described above is mainly composed of ethylene units and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units remaining without being saponified.

The EVOH resin used as a material for the EVOH resin pellet may further contain a structural unit derived from the comonomer shown below. The comonomer includes α-olefins such as propylene, isobutene, α-octene, α-dodecene and α-octadecene, 3-butene-1-ol, 4-pentene-1-ol, 3-butene-1,2-diol. Hydroxy group-containing α-olefins such as, esterified products thereof, hydroxy group-containing α-olefin derivatives such as acylated products, hydroxy groups such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol. Alkyl vinylidenes; hydroxyalkyl vinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, 1,3-dibutyronyloxy-2-methylenepropane, It is a comonome such as an unsaturated carboxylic acid or a salt thereof, a partially alkyl ester, a completely alkyl ester, a nitrile, an amide, an anhydride, an unsaturated sulfonic acid or a salt thereof, a vinylsilane compound, vinyl chloride, and styrene.

Further, "post-denatured" EVOH-based resins such as urethanization, acetalization, cyanoethylation, and oxyalkyleneization may be used as the EVOH resin.
Among the above-mentioned modified products, the EVOH resin in which the primary hydroxyl group is introduced into the side chain by copolymerization is preferable in that the secondary moldability such as stretching treatment and vacuum / pressure molding is improved, and among them, 1, 2 An EVOH resin having a −diol structure in the side chain is preferable.

The ethylene unit content (ethylene unit content) of the EVOH resin constituting the EVOH resin pellet group is 20 to 60 mol%, preferably 25 to 55 mol%. If the ethylene unit content is too low, the gas barrier property and appearance of the obtained molded product, especially the stretched film at high humidity, tend to deteriorate, and conversely, if it is too high, the gas barrier property of the stretched film tends to deteriorate. ..

The degree of saponification of the vinyl ester component in the EVOH resin is usually 90 mol% or more, preferably 90 to 99.99 mol%, and particularly preferably 92 to 99.99 mol%. If the degree of saponification is too low, the gas barrier property and moisture resistance of the stretched film tend to decrease, which is not preferable.

The melt flow rate (MFR) (210 ° C., load 2160 g) of the EVOH resin constituting the EVOH resin pellet group is usually 1 to 100 g / 10 minutes, preferably 2 to 50 g / 10 minutes, and particularly preferably 3 to 30 g. / 10 minutes. If the MFR is too large, the mechanical strength of the molded product tends to deteriorate, and if it is too small, the extrusion processability during molding tends to deteriorate.

The copolymerization conditions for synthesizing the EVOH resin as described above are not particularly limited, but the following conditions are usually preferably used.
Examples of the solvent used for such copolymerization usually include lower alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone and methyl ethyl ketone, and industrially, methanol is preferably used.
The amount of the solvent used may be appropriately selected in consideration of the chain transfer constant of the solvent according to the degree of polymerization of the target copolymer. For example, when the solvent is methanol, S (solvent) / M (solvent) / M ( Monomer) = 0.01 to 10 (weight ratio), preferably selected from the range of about 0.05 to 7 (weight ratio).

Examples of the polymerization catalyst used in the copolymerization include known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauryl peroxide, and t-butylperoxyneodecanoate and t-butyl. Peroxypivalate, α, α'bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl- Peroxyesters such as 1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate, di-n-propylperoxydicarbonate, di-iso-propyl Peroxydicarbonate], di-sec-butyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di (2-ethylhexyl) peroxydi Peroxydicarbonates such as carbonate, dimethoxybutylperoxydicarbonate, di (3-methyl-3-methoxybutylperoxy) dicarbonate, 3,3,5-trimethylhexanoyl peroxide, diisobutyryl peroxide, lauroyl Examples thereof include low temperature active radical polymerization catalysts such as diacyl peroxides such as peroxide.
The amount of the polymerization catalyst used varies depending on the type of catalyst and cannot be unconditionally determined, but is arbitrarily selected according to the polymerization rate. For example, when azobisisobutyronitrile or acetyl peroxide is used, it is preferably 10 to 2000 ppm, particularly preferably 50 to 1000 ppm, based on the vinyl ester-based monomer.

It is preferable that a hydroxylactone compound or a hydroxycarboxylic acid coexists with the above catalyst. Coloring of pellets can be suppressed. The hydroxylactone-based compound is not particularly limited as long as it has a lactone ring and a hydroxyl group in the molecule, and examples thereof include L-ascorbic acid, erythorbic acid, and gluconodeltalactone, which are preferable. L-ascorbic acid and erythorbic acid are used, and examples of the hydroxycarboxylic acid include glycolic acid, lactic acid, glyceric acid, malic acid, tartaric acid, citric acid, salicylic acid, and the like, and citric acid is preferably used. Be done.

The amount of the hydroxylactone compound or hydroxycarboxylic acid used is 0.0001 to 0.1 parts by weight, more preferably 0.0005 to 100 parts by weight, based on 100 parts by weight of the vinyl ester monomer in both the batch type and the continuous type. 0.05 parts by weight, particularly 0.001 to 0.03 parts by weight is preferable, and if the amount used is too small, the coexistence effect may not be sufficiently obtained, and conversely, if it is too large, the vinyl ester-based monomer This is not preferable as a result of inhibiting polymerization. The preparation of such a compound in a polymerization system is not particularly limited, but is usually an aliphatic ester containing a lower aliphatic alcohol (methanol, ethanol, propanol, tert-butanol, etc.) or a vinyl ester-based monomer (methyl acetate, ethyl acetate). Etc.), diluted with a solvent such as water, or a mixed solvent thereof, and charged into the polymerization reaction system.

Although the copolymerization reaction cannot be unequivocally determined depending on the solvent and pressure used, it is usually carried out below the boiling point of the solvent, and is usually carried out at 40 to 80 ° C., preferably 55 to 80 ° C. If the temperature is too low, polymerization takes a long time, and if the polymerization time is to be shortened, a large amount of catalyst is required. On the contrary, if the temperature is too high, polymerization control becomes difficult, which is not preferable.

In the case of the batch type, the polymerization time is preferably 4 to 10 hours (further, 6 to 9 hours). If the polymerization time is too short, the polymerization temperature must be raised or the amount of catalyst must be set to be large, and conversely, if the polymerization time is too long, it is not preferable from the viewpoint of productivity. In the case of the continuous type, the average residence time in the polymerization can is preferably 2 to 8 hours (further, 2 to 6 hours), and if the residence time is too short, the polymerization temperature must be raised or a large amount of catalyst must be set. On the contrary, if the polymerization time is too long, there is a problem in terms of productivity, which is not preferable.

The polymerization rate (vinyl ester-based monomer) is set as high as possible within the range where polymerization can be controlled from the viewpoint of productivity, and is preferably 20 to 90%. If the polymerization rate is too low, there are problems such as productivity and the presence of a large amount of unpolymerized vinyl acetate monomer. On the contrary, if the polymerization rate is too high, polymerization control becomes difficult, which is not preferable.

After polymerization for a predetermined time, after reaching a predetermined polymerization rate, a polymerization inhibitor is added as necessary to evaporate and remove unreacted ethylene gas, and then unreacted vinyl ester is expelled.
As a method for removing unreacted vinyl ester from the ethylene-vinyl ester copolymer obtained by evaporating and removing ethylene, for example, the copolymer solution is continuously applied at a constant rate from the upper part of a column filled with Raschig ring. While blowing organic solvent vapor such as methanol from the bottom of the tower, a mixed vapor of organic solvent such as methanol and unreacted vinyl ester was distilled off from the top of the tower, and the unreacted vinyl ester was removed from the bottom of the tower. A method of taking out the polymer solution or the like is adopted.

An alkali catalyst is added to the copolymer solution from which the unreacted vinyl ester has been removed, and the vinyl ester component in the copolymer is saponified.
Such saponification is carried out by using an alkali catalyst or an acid catalyst in a state where the copolymer obtained above is dissolved in an alcohol or a hydrous alcohol. Examples of the alcohol include methanol, ethanol, propanol, tert-butanol and the like, and methanol is particularly preferably used. The concentration of the copolymer in the alcohol is appropriately selected depending on the viscosity of the system, but is usually selected from the range of 10 to 60% by weight. The catalysts used for saponification include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium esterate, potassium methylate, lithium methylate, and alkali catalysts such as alcoholate; sulfuric acid, Examples thereof include acid catalysts such as hydrochloric acid, nitrate, metasulfonic acid, zeolite, and cation exchange resin.

The amount of the saponification catalyst used is appropriately selected depending on the saponification method, the target degree of saponification, etc., but when an alkali catalyst is used, it is usually based on the total amount of monomers such as vinyl ester-based monomers. 0.001 to 0.1 equivalents, preferably 0.005 to 0.05 equivalents, are suitable. Regarding such a saponification method, batch saponification, continuous saponification on a belt, and continuous saponification on a belt can be performed according to the target degree of saponification, and the amount of alkaline catalyst can be reduced at the time of saponification. Tower-type saponification under constant pressurization is preferably used because the conversion reaction is highly efficient and easy to proceed.
The pressure at the time of saponification cannot be unequivocally determined depending on the ethylene unit content of the target EVOH resin, but it is selected from the range of ^{2 to} 7 kg / cm ² , and the saponification temperature is 80 to 150 ° C., preferably 100 to 100. It is 130 ° C. and the saponification time is selected from 0.5 to 3 hours. The EVOH resin after the reaction is preferably neutralized if necessary.

As an EVOH resin to be a pellet raw material, a compounding agent generally blended with the EVOH resin synthesized as described above to the extent that the effect of the present invention is not impaired, for example, a heat stabilizer, an antioxidant, and an antistatic agent. Inhibitors, colorants, UV absorbers, plasticizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, cross-linking agents, hardeners, foaming agents, crystal nucleating agents, antifogging agents , An EVOH resin composition containing an additive for biodegradation, a silane coupling agent, an oxygen absorber and the like may be used.

<Manufacturing of pellets>
The pellet group of the present invention is a pellet group composed of the above-mentioned EVOH resin. The shape of the pellets in such a pellet group includes a columnar shape, a rectangular parallelepiped shape, a spherical shape, and the like, and is preferably a pellet group containing an EVOH resin pellet having a spherical shape, that is, a circular or elliptical cross section. The cross section is a cross section of the pellet without particular limitation, which means that any cut cross section is circular or elliptical.

The "spherical pellet" in the present invention means a pellet having a shape having no corners when viewed three-dimensionally and having a curved surface as a whole, and having a rounded shape. Specific examples thereof include a true sphere, an oval shape such as a disk shape or an ellipse shape, and an oval shape. Such pellets are usually
(1) Obtained by melt-extruding and cutting the EVOH resin in a molten state. If the EVOH resin is melt-extruded from the holes and cut with a cutter before it is cooled and solidified, the edge portion generated by the cutting hangs down during the cooling and solidification, and it acts to become spherical due to surface tension. No pellets are obtained that are entirely curved. Alternatively,
(2) Similarly, when the EVOH resin solution is extruded from the holes, cut with a cutter, and then solidified in the coagulating liquid, pellets composed of curved surfaces can be obtained by surface tension until the solution is completely solidified. .. Further drying gives pellets contained in the pellet group of the present invention.

As a raw material for cutting the EVOH resin pellets contained in the pellet group of the present invention in a molten state, (1-1) a solution or slurry of an EVOH resin obtained by saponification in the above-mentioned EVOH resin synthesis method. , Or the hydrous EVOH resin after appropriately adjusting the water content of the solution or slurry, or (1-2) dried EVOH resin can be used.

(1-1) When a hydrous EVOH resin is used as a raw material When a hydrous EVOH resin is used as a raw material for the EVOH resin pellets contained in the pellet group of the present invention, 0 to 10 parts by weight of alcohol is added to 100 parts by weight of the EVOH resin. A hydrous EVOH resin containing 10 to 500 parts by weight of water is preferable.

When a hydrous EVOH resin having a high alcohol content is used, it is not possible to prevent the alcohol from volatilizing in the subsequent process, and it becomes difficult to protect the working environment or the surrounding environment. Further, when the temperature of the pellet washing water is raised to remove alcohol, the pellets tend to stick to each other, and conversely, washing at a low temperature prolongs the washing time and causes a decrease in production efficiency.
On the other hand, when a hydrous EVOH resin having a high water content is used, when cutting in a molten state, the pellets after cutting tend to fuse with each other or the pellet shape tends to be inhomogeneous. When the content of the water-containing EVOH resin is small, the melt fluidity of the hydrous EVOH resin is insufficient, and the productivity of pellets tends to decrease.

The method for adjusting the water content of the water-containing EVOH resin for pellet production is not particularly limited, but in order to increase the water content, a method of spraying water on the resin, a method of immersing the resin in water, or a method of contacting the resin with water vapor is applied. The method can be adopted. In order to reduce the water content, it may be appropriately dried, and for example, it can be dried using a fluid hot air dryer or a static hot air dryer. From the viewpoint of reducing dry spots, it is preferable to use a fluid hot air dryer. Further, from the viewpoint of suppressing thermal deterioration, the drying temperature is preferably 120 ° C. or lower.

The saponified EVOH resin solution is usually obtained as a solution containing a large amount of alcohol, but by contacting the saponified EVOH resin solution with water vapor, a hydrous EVOH resin having a low alcohol content is derived from the container. , Can be used as a raw material for pellet production.

When the hydrous EVOH resin is put into a melt extruder as a pellet raw material, the temperature of the EVOH resin hydrous composition in the extruder is preferably 70 to 170 ° C., more preferably 80 ° C. or higher, still more preferably 90 ° C. or higher and 170. It is below ° C. If the temperature of the water-containing EVOH resin is less than 70 ° C., the EVOH resin may not be completely melted, and if it exceeds 170 ° C., the EVOH may be susceptible to thermal deterioration. In the present specification, the temperature of the resin composition means the temperature detected in the vicinity of the ejection port at the tip of the extruder by the temperature sensor installed in the extruder cylinder.

The extruder used is not particularly limited, but from the viewpoint of ease of handling the pellets, the diameter of the holes of the die is usually 1 to 10 mm, preferably 2 to 5 mm.
The number of cutter blades is usually 2 to 24, preferably 3 to 16.
The cutter blade is usually preferably attached so as to be in contact with the discharge port of the die of the extruder. Therefore, the distance between the die and the cutter is 0 mm, but even if there is a distance of about 0.01 to 0.2 mm. Good.
The rotation speed of the cutter blade is usually 200 to 2000 rpm, preferably 500 to 1000 rpm.
The shape of the pellet can be adjusted by appropriately adjusting the diameter of the nozzle, the number of cutter blades, the number of rotations of the cutter blades, and the like.

The molten EVOH resin extruded from the die is cut before being cooled and solidified (hot cut method). The hot-cut method may be either cut in the air (air hot-cut method) or extruded into a cutter-installed container filled with cooling water and cut in cooling water (underwater cut method). The underwater cutting method can be performed using, for example, an underwater pelletizing device.

The temperature of the cooling water in the underwater cutting method is such that the EVOH resin extruded in the molten state does not instantly solidify (solidify), and when it comes into contact with the cooling water before cutting, the temperature of the cooling water is 30. The temperature is preferably ~ 90 ° C, more preferably 40-80 ° C.
Cooling water is not limited to water. Water / alcohol mixed solution; aromatic hydrocarbons such as benzene; ketones such as acetone and methyl ethyl ketone; ethers such as dipropyl ether; organic esters such as methyl acetate, ethyl acetate and methyl propionate may also be used. it can. Of these, water or a water / alcohol mixed solution is used because it is easy to handle. In the water / alcohol mixed solution, the water / alcohol (weight ratio) is usually 90/10 to 99/1. As the alcohol, alcohols such as methanol, ethanol, and propanol can be used, and methanol is preferably used industrially.

(1-2) When a dried EVOH resin is used as a raw material When a dried EVOH resin is used as a raw material for EVOH resin pellets, the dried EVOH resin is put into an extrusion kneader and melt-extruded.
The size and shape of the dried EVOH resin used as a raw material are not particularly limited. The temperature of the EVOH resin in the extrusion kneader needs to be set higher than that in the case of the EVOH resin water-containing composition. Specifically, it is usually 150 to 300 ° C, preferably 200 to 285 ° C, and particularly preferably 240 to 270 ° C. If the set temperature is less than 150 ° C., the EVOH resin pellets tend not to melt completely. On the contrary, when the EVOH resin temperature exceeds 300 ° C., the EVOH resin tends to be susceptible to thermal deterioration. The resin temperature refers to the temperature detected near the discharge port at the tip of the extruder by a temperature sensor installed in the extruder cylinder.

The extruder used is not particularly limited, but from the viewpoint of ease of handling of pellets, the diameter of the hole of the die is usually 1.0 to 5.0 mm, preferably 2.0 to 3.5 mmφ. Is.
The cutter blade is usually preferably attached so as to be in contact with the discharge port of the die of the extruder. Therefore, the distance between the die and the cutter is 0 mm, but even if there is a distance of about 0.01 to 0.2 mm. Good.
The number of cutter blades is usually 2 to 24, preferably 3 to 16. The rotation speed of the cutter blade is usually 1000 to 2000 rpm, preferably 1250 to 1750 rpm.
The shape of the pellet can be adjusted by appropriately adjusting the diameter of the nozzle, the number of cutter blades, the number of rotations of the cutter blades, and the like.

The melt-extruded EVOH resin is cut before being cooled and solidified (hot cut method). As for the hot-cut method, either the aerial hot-cut method or the underwater hot-cut method may be adopted as in the case of using the hydrous EVOH resin as a raw material, and the temperature of the cooling water in the underwater cut method is also the same. , Usually 30 to 90 ° C, preferably 40 to 80 ° C. The cooling water is not limited to water, and solutions such as those listed when a hydrous EVOH resin is used as a raw material may be used as the cooling water.

If necessary, the EVOH resin pellets thus obtained are blended with a compounding agent generally blended with the EVOH resin, for example, an antioxidant, an antistatic agent, a colorant, and ultraviolet rays, as long as the effects of the present invention are not impaired. Absorbents, lubricants, plasticizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, cross-linking agents, hardeners, foaming agents, crystal nucleating agents, antifogging agents, biodegradation additions Agents, silane coupling agents, oxygen absorbers and the like may be contained.

(2) When an EVOH resin solution is used as a raw material When an EVOH resin solution is used as a raw material for the EVOH resin pellets contained in the pellet group of the present invention, the solvent for dissolving the EVOH resin is a solvent capable of dissolving the EVOH resin. It may be dissolved, and the solvent and method thereof are not limited, but the solvent includes solvents such as alcohol, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), hexafluoroisopropanol (HFIP), and these. An aqueous solution (mixed solvent) containing a solvent can be mentioned. Of these, a mixed solvent of alcohol and water is preferable, and an EVOH resin solution containing 100 to 200 parts by weight of alcohol and 10 to 50 parts by weight of water is preferable with respect to 100 parts by weight of the EVOH resin.
With an EVOH resin solution having a low alcohol content, the stability of the solution tends to decrease and the friction angle of the obtained pellet group tends to decrease. On the other hand, even with an EVOH resin solution having a high water content, the stability of the solution tends to decrease and the friction angle of the obtained pellet group tends to decrease.

The concentration of the EVOH resin contained in the EVOH resin solution is usually 10 to 60% by weight, preferably 15 to 50% by weight. If the concentration is too low, coagulation in the coagulating liquid becomes difficult, and conversely, if the concentration is too high, the stability of the solution becomes poor and precipitation occurs in the piping, or the viscosity of the solution becomes high and handling becomes difficult, which is not preferable. ..

The method for adjusting the alcohol content and water content of the EVOH resin solution for pellet production is not particularly limited, but the alcohol content is obtained by contacting the EVOH resin solution containing a large amount of normal alcohol after saponification with water vapor. , The water content can be adjusted, and alcohol and water can be added to the solution. As the alcohol, alcohols such as methanol, ethanol, and propanol can be used, and methanol is preferably used industrially.

The EVOH resin solution is extruded from the perforated die using any pump or extruder. The temperature of the EVOH resin solution at this time is usually 30 to 80 ° C., preferably 40 to 70 ° C., particularly preferably 50 to 68 ° C., and further preferably 61 to 65 ° C. The diameter (diameter) of the hole is usually 1 to 10 mm, preferably 2 to 5 mm.
The number of cutter blades is usually 2 to 24, preferably 3 to 16.
The cutter blade is usually preferably attached so as to be in contact with the discharge port of the die of the extruder. Therefore, the distance between the die and the cutter is 0 mm, but even if there is a distance of about 0.01 to 0.2 mm. Good.
The rotation speed of the cutter blade is usually 100 to 2000 rpm, preferably 500 to 1500 rpm.
The shape of the pellet can be adjusted by appropriately adjusting the diameter of the nozzle, the number of cutter blades, the number of rotations of the cutter blades, and the like.

The EVOH resin solution is extruded from a die into a cutter-installed container filled with a coagulating liquid and cut in the coagulating liquid (in-liquid cutting method).
The temperature of the coagulating liquid in the submerged cutting method is usually -20 to 20 ° C, preferably 0 to 10 ° C, and more preferably 4 ° C to 8 ° C. If the temperature of the coagulating liquid is too low, the friction angle tends to be small, and if it is too high, coagulation does not proceed and the pellets tend to fuse with each other.
The coagulation liquid is water; water / alcohol mixed solution; aromatic hydrocarbons such as benzene; ketones such as acetone and methyl ethyl ketone; ethers such as dipropyl ether; organic esters such as methyl acetate, ethyl acetate and methyl propionate. Etc. can also be used. Of these, water or a water / alcohol mixed solution is used because it is easy to handle. In the water / alcohol mixed solution, the water / alcohol (weight ratio) is usually 50/50 to 99/1, preferably 60/40 to 90/10, and particularly preferably 65/35 to 80/20. As the alcohol, alcohols such as methanol, ethanol, and propanol can be used, and methanol is preferably used industrially.

The pellets obtained as described above are preferably further washed with water. Although it depends on the raw material used, if there is a possibility that it contains an alkali metal salt that is the catalyst residue used during saponification, wash it with water from the viewpoint of preventing coloring of the finally obtained molded product. Is preferable.

Washing with water is carried out in a water tank at 10 to 60 ° C. For example, 200 to 1000 parts by weight (preferably 300 to 600 parts by weight) of water with respect to 100 parts by weight of EVOH resin pellets at 20 to 50 ° C. (preferably 25 to 35 ° C.) for 0.5 to 5 hours. It is preferable to carry out 1 to 5 times (preferably once). By such washing with water, the contents of alcohol, acetic acid, and sodium acetate having 5 or less carbon atoms in the EVOH resin can be adjusted, and oligomers and impurities can also be removed.

By washing with water, with respect to 100 parts by weight of EVOH resin pellets, usually 0.0001 to 1 part by weight of alcohol having 5 or less carbon atoms, 0.01 to 1 part by weight of acetic acid, and 0.01 to 1 part by weight of sodium acetate. It is preferable to adjust to the part.

After washing with water, the EVOH resin pellets are brought into contact with an aqueous solution of the additive, if necessary. As additives, for example, organic acids such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, alkali metal salts (sodium, potassium, etc.) and alkaline earth metal salts (calcium, potassium, etc.) thereof. Salts such as magnesium), zinc salts; or inorganic acids such as sulfuric acid, sulfite, carbonic acid, phosphoric acid, boric acid, or alkali metal salts (sodium, potassium, etc.) and alkaline earth metal salts (calcium, magnesium). Etc.), heat stabilizers such as salts such as zinc salts can be mentioned.
Of these, it is particularly preferable to add acetic acid, boric acid and boron compounds containing boric acid and salts thereof, acetates and phosphates.
By contacting with an aqueous solution of such an additive, the additive can be contained in the EVOH resin pellet, and various physical properties such as thermal stability during melt molding can be improved.
As a method of contacting with the aqueous solution of the additive, an aqueous solution of 3% or less (preferably 0.0003 to 1.5%) of the additive is added to 100 parts by weight of the EVOH resin pellet by 200 to 1000 parts by weight (preferably). (300 to 600 parts by weight), carried out at 10 to 80 ° C. (preferably 20 to 60 ° C., particularly preferably 30 to 40 ° C.) for 0.5 to 5 hours, 1 to 3 times (preferably once). Will be done.

By the operation of contacting with the aqueous solution of the additive, acetic acid is usually 0.001 to 1 part by weight and the boron compound is converted to boron (after ashing, analyzed by ICP emission analysis method) with respect to 100 parts by weight of EVOH resin pellets. ) To 0.001 to 1 part by weight, acetic acid salt or phosphate (including hydrogen phosphate) in terms of metal (after ashing, analyzed by ICP luminescence analysis method) 0.0005 to 0.1 weight It is preferable to adjust to the part.

As described above, the EVOH resin pellet in which the concentration of each component is adjusted is dried. The water content of the EVOH resin pellets after drying is usually 1% by weight or less, particularly 0.5% by weight or less.
The drying method is not particularly limited, and examples thereof include a method using a centrifugal dehydrator, a method of draining water during air transportation, a static drying method, a fluid drying method, and the like, and many drying methods are combined. A stepwise drying step may be performed.

If necessary, the EVOH resin pellets thus obtained are blended with a compounding agent generally blended with the EVOH resin, for example, an antioxidant, an antistatic agent, a colorant, and ultraviolet rays, as long as the effects of the present invention are not impaired. Absorbents, lubricants, plasticizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, cross-linking agents, hardeners, foaming agents, crystal nucleating agents, antifogging agents, biodegradation additions Agents, silane coupling agents, oxygen absorbers and the like may be contained.

The EVOH resin pellet group of the present invention includes EVOH resin pellets obtained by the method as described above, and in the pellet group of the present invention, at least 50% of the pellets have a friction angle of 20 to 40 ° with respect to the stainless steel plate. In a group of pellets with a large number of pellets with a friction angle of less than 20 ° and less than 50% of pellets with a friction angle of 20 to 40 °, the pellets may fall off or be damaged due to unexpected flow during transportation or storage of the pellets. Tends to spread over a wide area and tends to be difficult to handle. In a group of pellets with less than 50% of pellets with a friction angle of 20 to 40 ° and many pellets with a friction angle of more than 40 °, the discharge fluctuation tends to be large during melt processing, which is not preferable because of insufficient fluidity. ..
More specifically, 10 or more pellets are arranged on a stainless standard test plate used in JIS Z0237 (adhesive tape / adhesive sheet test method) in an environment of 23 ° C. and 50% relative humidity so as not to come into contact with each other, and the inclination angle is 1. When the plate is tilted to increase at ° / sec, the pellet rolls down or slides down. When the angle of inclination is the friction angle, at least 50% of the pellets have an angle of 20 to 40 °. It is a group.
The angle of repose is sometimes measured as a method for evaluating the fluidity of the pellet group, and while the angle of repose is used as an index showing the frictional force between pellets, the inclination angle of the present invention is the ease of rolling of the pellet itself. Or, it is a different index in that it is an index showing the frictional force with an object other than pellets.

The method for forming a pellet group containing at least 50% of pellets having a friction angle of 20 to 40 ° is not particularly limited, but the pellet shape is (A) in the vertical direction when the pellet is spherical and the pellet is stationary. The shape of the cross section that gives the maximum cross-sectional area is the same as the overlapping part of the two circles when two circles with different radii intersect at two points and the center of the small circle is inside the large circle. It becomes possible by doing.
(B) This is possible when the pellet shape is disk-shaped or elliptical, and the height with respect to the diameter of the disk or the minor axis of the ellipse is 1/2 or less.

In the case of (A), the size of the pellet is not particularly limited, but the average diameter (r) of the cross section at which the maximum horizontal cross-sectional area can be obtained when the pellet is stationary is usually 3 to 6 mm, preferably 3.5 to. It is 5.5 mm, particularly preferably 4.3 to 5.2 mm, and the vertical height (h) of the cross section at which the maximum vertical cross section is obtained is usually 0.5 to 4 mm, preferably 1 to 3 mm. Particularly preferably, it is 1.5 to 2.5 mm, and the point where the above-mentioned cross section in the horizontal direction and the line corresponding to the height (h) in the vertical direction intersect is the height (h) from the center of the height (h) in the vertical direction. It is necessary to be separated from 1/10 to 4/10 of h), and if it is smaller than 1/10, the pellets tend to roll easily and the friction angle tends to be less than 20 °. If it exceeds 4/10, the fluidity tends to be large. Tends to decrease and the friction angle tends to exceed 40 °.

In the case of (B), the size of the pellet is not particularly limited, but the maximum major axis (m) of the cross section at which the maximum horizontal cross-sectional area can be obtained when the pellet is stationary is usually 3 to 6 mm, preferably 3.5 to. It is 5.5 mm, particularly preferably 4.3 to 5.2 mm, and the minimum minor axis (n) is usually 1.5 to 6 mm, preferably 2 to 4.5 mm, particularly preferably 2.5 to 3. The vertical height (h) of the cross section is 5 mm and the maximum vertical cross-sectional area can be obtained, usually 0.5 to 3 mm, preferably 0.7 to 2.2 mm, particularly preferably 0.5 to 2 mm. The ratio (h) / (n) of the height (h) in the vertical direction to the minimum minor axis (n) in the horizontal direction is 1/2 or less, and usually 1/5 or more. If (h) / (n) exceeds 1/2, the pellets tend to roll easily and the friction angle tends to be less than 20 °. If it is less than 1/5, the fluidity becomes extremely small and the friction angle becomes It tends to be larger than 40 °. The pellet must be covered with a curved surface, and the cross section for which the maximum vertical cross section is obtained is also circular or elliptical, not quadrangular. For pellets having a quadrangular cross section, the friction angle tends to be larger than 40 °, and the fluidity of the pellet group decreases.

In order to form the pellet into the shape of (A), the extrusion rate when cutting the molten resin composition from the nozzle by the method (1-1) or (1-2) of the pellet manufacturing method described above is used. By adjusting the rotation speed of the blade, the point where the cross section in the horizontal direction and the line corresponding to the height (h) in the vertical direction intersect is 1 of the height (h) from the center of the height (h) in the vertical direction. It can be separated from / 10 to 4/10.
However, as a method for obtaining the pellet group of the present invention, it is preferable that the pellet has the shape of (B) because the pellet shape can be easily prepared, and the pellet having the shape of (B) is obtained. In the method (2) of the production method of (2), the resin composition immediately after cutting may be made flexible. For example, a method of lowering the resin content concentration of the EVOH resin solution, a water / alcohol solvent of the EVOH resin solution, A method of increasing the alcohol ratio of, a method of increasing the temperature of the EVOH resin solution, a method of increasing the alcohol ratio of the coagulating liquid that coagulates the EVOH resin solution after cutting, a method of increasing the temperature of the coagulating liquid, and the amount of lubricant. There is a method of adjusting the surface texture of the resin. These methods may be combined.

(Mixing of pellets)
The pellet group of the present invention may be a mixture of two or more kinds of pellets in which one or some of the ethylene unit content, the degree of saponification, the melt flow rate, the shape, etc. are different.
As a method of mixing two or more kinds of pellets, for example, a mechanical mixing method, specifically, a mixing device such as a Banbury mixer may be used, or the mixture is mixed by manually stirring and shaking. You may.

<Use>
The EVOH resin pellet group of the present invention having the above-mentioned structure is excellent in feedability and handleability, and is therefore preferably used as a molding material for producing an EVOH resin molded product. In particular, it can be suitably used as a melt extrusion molding material for films, sheets, fibers and the like. As such a melt molding method, an extrusion molding method (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and an injection molding method are mainly adopted.

The conditions and types of the molding machine to be used are not particularly limited, and the melt plasticizing portion may be either a screw type or a plunger type, but is preferably a screw type. The extruder may be either a vertical type or a horizontal type, and may be a single screw type or a twin screw type. Further, the screw L / D (screw length / screw diameter) and compression ratio (C) are not particularly limited, but the normal L / D is 20 to 35, preferably 25 to 30, and the normal C is 1.5 to 8. , Preferably selected from the range of 2-5.
The melt molding temperature is generally selected from the range of 150 to 300 ° C.

The film or sheet can be used as it is for various purposes by molding, but it is usually used as a laminate by laminating it with another base material in order to further increase the strength or impart other functions. The EVOH resin film, sheet or laminate thereof obtained by using the pellet group of the present invention is used as a packaging material for food packaging materials, industrial chemical packaging materials, pesticide packaging materials and the like based on its excellent gas barrier properties. Further, the EVOH resin film, the sheet or a laminate thereof may be further molded into a cup, a bottle or the like.

Thermoplastic resin is useful as another base material used for the laminate. Examples of the thermoplastic resin include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene and other polyethylenes, polypropylene, ethylene-propylene (block and random) copolymers, and propylene. -Α-Olefin (α-olefin having 4 to 20 carbon atoms) copolymers, polyolefins such as polybutene and polypentene, grafted polyolefins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or esters thereof, ionomers, ethylene -Vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polyester resin, polyamide resin (including copolymer polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin , Polyolefins, vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylenes, halogenated polyolefins such as chlorinated polypropylenes, aromatic or aliphatic polyketones, and polyalcohols obtained by reducing these. From the viewpoint of practicality such as physical properties (particularly strength) of the laminate, polyolefin-based resins and polyamide-based resins are preferable, and polyethylene and polypropylene are particularly preferably used.
As the other base material, any base material (paper, metal leaf, uniaxial or biaxially stretched plastic film or sheet, woven fabric, non-woven fabric, metal cotton-like, wood, etc.) may be used in addition to the thermoplastic resin. ..

These base resin contains antioxidants, antistatic agents, lubricants, core materials, blocking inhibitors, ultraviolet absorbers, waxes and the like as conventionally known, as long as the gist of the present invention is not impaired. You can stay.

When laminating with another base material using the pellet group of the present invention, a known laminating method can be used. For example, a method of melt-extruding and laminating another base material on a film, sheet or the like using the pellet group of the present invention, conversely, a method of melt-extruding and laminating the resin on another base material, the resin and another base material. A method of coextruding the resin (layer) and another base material (layer) by dry laminating with a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound, or the like. Examples thereof include a method of applying a solution of the resin on a base material and then removing the solvent.
Among these, the coextrusion method is preferable from the viewpoint of cost and environment. Even when the pellet group of the present invention is used, it can be applied to extrusion molding with other thermoplastic resins. Since the pellet group of the present invention is excellent in film moldability, that is, fluctuations in the film width to be melt-extruded are suppressed, the production of a multilayer structure applied to melt co-extrusion with other thermoplastic resins is produced. Can be suitably used for.

The shape of the laminate is not particularly limited, and examples thereof include films, sheets, tapes, bottles, pipes, filaments, and extruded cross-sections. The layer structure of the laminate is a film when the EVOH resin layer is x (x1, x2, ...) And another base material, for example, the thermoplastic resin layer is y (y1, y2, ...). , Sheet, bottle-shaped, not only x / y two-layer structure, but also y / x / y, x / y / x, x1 / x2 / y, x / y1 / y2, y2 / y1 / x / Any combination such as y1 / y2 is possible. In the filament type, any combination such as bimetal type, core (x) -sheath (y) type, core (y) -sheath (x) type, or eccentric core sheath type is possible.

The laminate can 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, if necessary. ..
The laminated body may be used as it is for various shapes, but it is also preferable to perform a stretching treatment in order to further improve the physical characteristics of the laminated body, and such stretching is performed by uniaxial stretching or biaxial stretching. Either of these may be used, and it is better to perform stretching at the highest possible magnification to obtain a stretched film, stretched sheet, or the like that does not cause pinholes, cracks, uneven stretching, delamination, etc. during stretching.

As the stretching method, in addition to the roll stretching method, the tenter stretching method, the tubular stretching method, the stretching blow method and the like, a deep drawing method, a vacuum forming and the like having a high drawing ratio can be adopted. In the case of biaxial stretching, either the simultaneous biaxial stretching method or the sequential biaxial stretching method can be adopted. The stretching temperature is selected from the range of 80 to 170 ° C., preferably about 100 to 160 ° C.

It is preferable to perform heat fixation after the stretching treatment. Heat fixing can be carried out by a well-known means, and the stretched film is heat-treated at 80 to 170 ° C., preferably 100 to 160 ° C. for about 2 to 600 seconds while maintaining a tense state.

When the laminated film is used for heat-shrinkable packaging of raw meat, processed meat, cheese, etc., after packaging the raw meat, processed meat, cheese, etc. using a film that is not heat-fixed after stretching, the temperature is 50 to 130 ° C. The film is heat-shrinked and tightly wrapped by performing a heat treatment at 70 to 120 ° C. for about 2 to 300 seconds.

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

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the description of Examples as long as the gist thereof is not exceeded.
In the example, the term "part" means a weight standard unless otherwise specified.

[Manufacturing of EVOH resin pellets]
<Example>
EVOH resin [ethylene content 50 mol%, saponification degree 93.7 mol%, MFR 25 g / 10 minutes (210 ° C., load 2160 g)] water / methanol mixed solution (water / methanol = 10/90 mixed weight ratio, EVOH resin concentration 38%, solution temperature 63 ° C) is extruded from a die with a hole diameter of 3.3 mm and two holes at a speed of 19 kg / hour, and cut at a rotation speed of 700 rpm with a cutter having five blades. After coagulating in a water / methanol mixed coagulation solution (water / methanol = 70/30 mixed weight ratio) at 5 ° C. for 1 minute or more, the resin component and the coagulation solution were separated to contain water and methanol. Elliptical EVOH resin pellets were obtained.
The EVOH resin pellets were washed with warm water at 35 ° C. to obtain pellets having a water content of 54%.
Further, the EVOH resin pellets were dried under nitrogen in a static dryer at a temperature of 118 ° C. for 12 hours to obtain a group of dried EVOH resin pellets having a water content of 0.06%. The obtained pellet had an elliptical shape with a major axis (m) of 5.0 mm and a minor axis (n) of 3.2 mm and a height (h) of 1.4 mm.
<Comparison example>
EVOH resin [ethylene content 32 mol%, saponification degree 99.8 mol%, MFR 12 g / 10 minutes (210 ° C., load 2160 g)] water / methanol mixed solution (water / methanol = 34/66 mixed weight ratio, EVOH resin concentration 40%, solution temperature 60 ° C.) is extruded from a die with a hole diameter of 3.3 mm and two holes at a speed of 20 kg / hour, and cut at a rotation speed of 700 rpm with a cutter having five blades. After coagulation in a water / methanol mixed coagulation solution (water / methanol = 70/30 mixed weight ratio) at 3 ° C. for 1 minute or more, the resin component and the coagulation solution were separated to contain water and methanol. Rugby ball-shaped EVOH resin pellets were obtained. The EVOH resin pellets were washed with warm water at 35 ° C. to obtain pellets having a water content of 52%.
Further, the EVOH resin pellets were dried under nitrogen in a static dryer at a temperature of 118 ° C. for 12 hours to obtain a group of dried EVOH resin pellets having a water content of 0.15%. The obtained pellet had a rugby ball shape with a major axis of 5.0 mm and a central diameter of 3.2 mm.

[Friction angle]
10 pellets from the pellet group obtained above are arranged on a stainless standard test plate used in JIS Z0237 (adhesive tape / adhesive sheet test method) in an environment of 23 ° C. and 50% relative humidity so as not to contact each other. , Tilt the plate so that the tilt angle increases at 1 ° / sec from the horizontal state, and the number of pellets that rolled down or slipped down until the tilt angle reached 20 ° rolled at 20-40 °. The number of pellets that fell or slipped off and the number of pellets that remained at 40 ° were counted, and the proportion of pellets with a friction angle of 20 to 40 ° was calculated.

From the results in Table 1, the EVOH resin pellet group in which the pellets having a friction angle of 20 to 40 ° in Examples are 80% naturally has good fluidity, excellent feedability, and good handleability.
The EVOH resin pellet group in which 10% of the pellets have a friction angle of 20 to 40 ° in Comparative Example has too high fluidity and poor handleability.

The EVOH pellet group of the present invention is extremely useful industrially because it has good fluidity, excellent feedability, and good handleability.

Claims (4)

A group of pellets of ethylene-vinyl ester copolymer saponified pellets.
Ri friction angle of 20 to 40 ° der at least 50% of the pellets to a stainless steel plate of the pellet group,
A group of ethylene-vinyl ester copolymer saponified pellets characterized in that the shapes of the ethylene-vinyl ester copolymer saponified pellets are as follows (A) and / or (B) .
(A) The shape of the cross section is spherical and the maximum cross-sectional area in the vertical direction can be obtained when the pellets are stationary. Two circles with different radii intersect at two points, and the center of the small circle is a large circle. Shape similar to the overlapping part of two circles when inside
(B) Disc-shaped or elliptical, with a height of 1/2 or less of the diameter of the disc or the minor axis of the ellipse The ethylene-vinyl ester-based copolymer saponified pellet group according to claim 1, wherein the shape of the ethylene-vinyl ester-based copolymer saponified pellet is the shape of (B) . The maximum major axis (m) of the cross section obtained by obtaining the maximum horizontal cross-sectional area of the ethylene-vinyl ester-based copolymer saponified pellet when the pellet is stationary is 3 to 6 mm, and the minimum minor axis (n) is The vertical height (h) of the cross section is 1.5 to 6 mm and the maximum vertical cross section is obtained, and the vertical height (h) is 0.5 to 3 mm with respect to the horizontal minimum minor axis (n). The ethylene-vinyl ester-based copolymer saponified pellet group according to claim 2, wherein the ratio (h) / (n) of (h) is 1/5 to 1/2. A molding material comprising the ethylene-vinyl ester-based copolymer saponified pellet group according to any one of claims 1 to 3 .