JP5236147B2 - Ethylene-vinyl alcohol copolymer and ethylene-vinyl alcohol copolymer resin composition - Google Patents

Description

The present invention is not only excellent in mechanical strength of a molded product when formed into a sheet or film, but also excellent in appearance with little coloration and unevenness of the film surface, and excellent in long run properties during melt molding. copolymers and now consists of ethylene - relates to vinyl alcohol copolymer resin composition.

  An ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is a useful polymer material excellent in oxygen shielding properties, oil resistance, non-charging properties, mechanical strength, etc. Widely used as packaging material. Such packaging materials are usually manufactured by melt molding, and have a long run property during melt molding (a molded product without fish eyes or streaks can be obtained even during long-time molding), mechanical properties (machines for films and molded products) Strength) and appearance of the molded product (low coloration and no occurrence of fish eyes) are required.

  In particular, mechanical properties are closely related to the molecular weight of EVOH as in general polymer compounds, and it is known that mechanical properties improve as the molecular weight increases. However, in a general EVOH production process in which a copolymer of ethylene and a vinyl ester is saponified, it is difficult to obtain EVOH having a large molecular weight in the polymerization step for the following reasons.

  Usually, in homogeneous polymerization such as solution polymerization and bulk polymerization, the heat of polymerization reaction is removed by a jacket or coil, but when trying to obtain an ethylene-vinyl ester copolymer having a large molecular weight, the viscosity of the polymerization reaction solution is very high. Thus, there is a problem that not only the heat removal capability is lowered and the productivity is extremely lowered, but also the reaction system becomes non-uniform due to the stirring spots and the quality becomes unstable. In the heterogeneous polymerization methods such as suspension polymerization and emulsion polymerization, there is no problem of such a reduction in heat removal ability, but in these cases, water is usually used as a dispersion medium in order to carry out the reaction in a dispersion system. Since it is difficult to completely remove this water from the dispersion after the reaction, a large amount of alkali catalyst is required in the subsequent saponification step, and much labor is required for the washing, or washing is insufficient. In such a case, another problem of causing coloring by alkali when EVOH is dried occurs.

  In addition, pure EVOH has poor thermal stability, and as it is, deterioration proceeds by being heated during melt molding, and it is impossible to avoid the occurrence of irregularities and coloring in the molded product. Attempts have been made so far to improve the thermal stability by using EVOH resin compositions containing such additives (see, for example, Patent Document 1). However, although these methods improve the unevenness and coloring in the molded product, there is still room for improvement in the phenomenon such as streaks in which streaky patterns occur on the surface of the molded product. .

  As a method for producing an ethylene-vinyl alcohol copolymer having excellent quality such as mechanical properties, it is described that the melt index is lowered by heat-treating the ethylene-vinyl alcohol copolymer (see, for example, Patent Document 2). ). Is disclosed. According to this, it is described that the melt index is lowered by heat-treating an ethylene-vinyl alcohol copolymer. However, the ethylene-vinyl alcohol copolymer used in this invention has a vinyl acetate unit content of 10 to 60% by weight. With such a low vinyl acetate content, sufficient oxygen barrier properties can be obtained when formed into a molded product. Absent. Further, in this invention, the saponification degree of the ethylene-vinyl alcohol copolymer is 50 to 99% by weight, but such a low saponification ethylene-vinyl alcohol copolymer has a low thermal stability. There is.

  Further, EVOH is disclosed in which the carboxylic acid or lactone ring present at the terminal of EVOH is reduced by reduction or amidation (see, for example, Patent Document 3). According to this, EVOH excellent in thermal stability is said to be obtained. However, in this method, the mechanical properties of EVOH are the same as those of the original EVOH, and a method for obtaining EVOH excellent in mechanical properties is obtained. Is not disclosed.

International Publication No. 2002/053639 Pamphlet Japanese Patent Application Laid-Open No. 60-79009 International Publication No. 2004/092234 Pamphlet

  An object of the present invention is to obtain EVOH having improved mechanical properties and streaks without reducing productivity and thermal stability.

As a result of intensive studies on the above problems, the inventors of the present invention have an ethylene content of 20 to 60 mol%, a saponification degree of 99.0 mol% or more, and an intrinsic viscosity η _F and an intrinsic viscosity η ₀ after alkali treatment are expressed by the formula 1. And the heat treatment is performed for 1 to 100 hours in an atmosphere having an oxygen concentration of 1000 ppm or less, and the temperature for performing the heat treatment is a melting point of the ethylene-vinyl alcohol copolymer before the heat treatment of -30 ° C or higher. The ethylene-vinyl alcohol copolymer having a water content of 0.25% or less before the heat treatment has found that these problems can be achieved simultaneously; The invention has been completed.
0.5 <η ₀ / η _F <0.95 Equation 1

Here, the alkali treatment refers to 4 g of EVOH that has been crushed by freeze pulverization and then sieved with a sieve having a nominal size of 1 mm (conforming to standard fluid standard JIS Z-8801) in a 300 mL Erlenmeyer flask. After adding 30 g of normal propyl alcohol, attaching a water-cooled condenser and repeating vacuum degassing 5 times, dissolving by heating and stirring at 80 ° C. for 3 hours, and then driving the reaction at 60 ° C. for another 3 hours It is. The intrinsic viscosity is a value calculated according to the following formula 2 from the number of seconds dropped using an Ostwald viscosity tube for a solution of EVOH dissolved in phenol / water = 85/15 (weight ratio) hydrous phenol: It is.
[Η] = (2 × (η _SP −ln η _r )) ^0.5 / C (L / g) Equation 2
η _SP = (t−t ₀ ) / t ₀ Formula 3
η _r = t / t ₀ Formula 4
C: EVOH concentration (g / L)
t ₀ : Blank falling seconds (s)
t: Number of seconds of falling of EVOH solution (s)

  The EVOH of the present invention makes it possible to obtain EVOH with improved mechanical properties and streak without reducing productivity and thermal stability.

In the EVOH of the present invention, when the intrinsic viscosity before alkali treatment is η _F and the intrinsic viscosity after alkali treatment is η ₀ , it is essential that these values satisfy the above formula 1.

The range of _{η 0 / η F, 0.55 <} η 0 / η F < more preferably from 0.93, more preferably from _{0.58 <η 0 / η F <} 0.91, It is particularly preferred that 0.60 <η ₀ / η _F <0.90. When the value of η ₀ / η _F is larger than 0.5, it is preferable because fish eyes in the molded product are reduced when EVOH is melt-molded. When the value of η ₀ / η _F is smaller than 0.95, the mechanical properties and streak improving effects which are the objects of the present invention can be obtained.

  EVOH is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and a vinyl ester. As is apparent from the reaction mechanism, the EVOH thus obtained is subjected to a chain transfer reaction to a vinyl ester monomer present in the polymerization reaction system or a vinyl ester-derived unit in the ethylene-vinyl ester copolymer. It has a structure such as a resulting carboxyl group or lactone ring at the molecular end. In the EVOH production process, EVOH is usually dried at a temperature as low as possible in order to reduce deterioration due to heat during drying. Under such conditions, the carboxyl group or lactone ring structure is stable. However, it is considered that the melt viscosity is increased by causing a crosslinking reaction with a hydroxyl group contained in the vinyl alcohol unit in EVOH relatively easily under a high temperature condition such as during melt molding. Such a change in viscosity at the time of melt molding causes a streak to the molded product.

  On the other hand, the EVOH of the present invention undergoes a crosslinking reaction between most of the carboxyl group or lactone ring structure and the hydroxyl group contained in the vinyl alcohol unit in EVOH in advance during drying or subsequent heat treatment. In the subsequent melt molding, the change in melt viscosity due to the crosslinking reaction is small, and as a result, the occurrence of streaks in the molded product is reduced. In addition, the molecular weight of EVOH can be increased by advancement of the crosslinking reaction in advance, and it is not necessary to increase the molecular weight of the ethylene-vinyl ester copolymer during polymerization. Can also solve the problem of lowering.

The esterification by the terminal group and the hydroxyl group in EVOH described above is hydrolyzed by the alkali treatment described above, the molecular weight of EVOH after the alkali treatment is lowered, and the intrinsic viscosity η ₀ is smaller than the intrinsic viscosity η _F before the alkali treatment. Become. The higher the degree of esterification of EVOH before alkali treatment, the greater the decrease in molecular weight due to alkali treatment, and the lower the degree of esterification, the smaller the decrease in molecular weight. Therefore, in the present invention, the value of η ₀ / η _F is used as an index for evaluating the degree of esterification.

With respect to the ethylene content and saponification degree of the EVOH of the present invention, 20 to 60 mol% ethylene content of the EVOH, is saponification degree of the vinyl ester moiety of 9 9 mol% or more. As ethylene content, More preferably, it is 22-55 mol%, More preferably, it is 24-50 mol% . Particularly good oxygen barrier properties at high humidity conditions by e styrene content is 20 mol% or more, excellent thermal stability, Ya oxygen barrier properties at low humidity conditions by which 60 mol% or less Excellent printability. On the other hand, when the degree of saponification is 90% or more, oxygen barrier properties, thermal stability, and moisture resistance are good.

  The EVOH production method of the present invention is not limited as long as the intrinsic viscosity of the finally obtained EVOH before and after alkali treatment satisfies the relationship of Formula 1, but is produced by the production method of the present invention described later. It is preferable.

  The EVOH of the present invention preferably contains 10 to 1000 ppm of alkali metal salt and 1000 ppm or less of phosphate from the viewpoint of thermal stability of the EVOH resin composition and adhesion when laminated with other resins. . Examples of the alkali metal salt include alkali metal salts such as sodium, potassium, rubidium, and cesium. Usually, sodium salt or potassium salt is preferably used. The counter anion of the alkali metal salt is not particularly limited, and examples thereof include a carbonate anion, an acetate anion, a propionate anion, a lactate anion, a stearate anion, a lauroylate anion, and a tartrate anion. There is no problem that the anion in the phosphate described later is used as the counter anion of the alkali metal salt. Examples of the phosphate include phosphate, monohydrogen phosphate, dihydrogen phosphate, and metaphosphate. As the phosphate counter cation, not only alkali metal ions such as sodium and potassium, alkaline earth metal ions such as magnesium and calcium, but also ions of transition metals such as iron, cobalt and nickel can be used.

  As content of an alkali metal salt, More preferably, it is 15-800 ppm, More preferably, it is 18-600 ppm, Most preferably, it is 20-500 ppm. When the content of the alkali metal salt is less than 10 ppm, it may not be possible to obtain a product having sufficient adhesion when laminated with other resins. When the content of the alkali metal salt exceeds 1000 ppm, the molded product after melt molding may be colored.

  The method for adding an alkali metal salt to EVOH is not particularly limited. For example, a method of immersing the EVOH in a solution in which the compound is dissolved, a method of melting the EVOH and mixing the compound, a method of dissolving the EVOH in an appropriate solvent and mixing the compound, etc. are applied. Is possible.

  Especially, in order to exhibit the effect of this invention more notably, the method of immersing EVOH in the solution of the said compound is desirable. This process can be performed by either a batch method or a continuous method. In this case, the shape of the EVOH may be any shape such as powder, granular, spherical, or cylindrical pellet.

  When EVOH is immersed in a solution containing acetic acid and an alkali metal salt, the concentrations of acetic acid and alkali metal salt in the solution are not particularly limited. The solvent of the solution is not particularly limited, but is preferably an aqueous solution from the viewpoint of ease of handling and influence on the environment. The preferred range of immersion time varies depending on the form of EVOH, but in the case of pellets of about 1 to 10 mm, it is 1 hour or longer, preferably 2 hours or longer.

  The immersion treatment of the various compounds in the solution may be divided into a plurality of solutions or may be performed at a time. Especially, it is preferable from the point of the simplification of a process to process with the solution containing an acetic acid and an alkali metal salt. When the treatment is performed by immersing in the solution as described above, the final EVOH composition is obtained by drying.

  The EVOH production method of the present invention is an EVOH production method in which the intrinsic viscosity before and after the alkali treatment satisfies the relationship of Formula 1, and is 1 at a temperature below the melting point of EVOH in an atmosphere having an oxygen concentration of 1000 ppm or less under normal pressure. The heat treatment is performed for ˜100 hours.

  About atmospheric oxygen concentration, More preferably, it is 500 ppm or less, More preferably, it is 200 ppm or less, More preferably, it is 100 ppm or less, Most preferably, it is 10 ppm or less. An oxygen concentration of 1000 ppm or more is not preferable because EVOH after heat treatment is colored.

  As an apparatus for performing heat treatment, the heating method can be either an indirect heating method or a direct heating method, and either a batch method or a continuous method may be used, and the atmosphere and temperature in the device are kept constant. It only has to be something that can be done. Specific examples include a hopper dryer, a fluidized bed dryer, a stationary hot air dryer, a rotary kiln, and a tumbler dryer, but are not limited thereto.

  There is no particular limitation on the method for adjusting the atmospheric oxygen concentration during the heat treatment to the above preferable range. For example, in the case of the indirect heating method using stationary or fluid hot air such as a hopper dryer or fluidized bed dryer, a mixed gas of an inert gas such as nitrogen or argon and air is used as the hot air, and the mixing ratio The method of adjusting by is mentioned. In addition, when using the direct heating method with a rotary kiln or tumbler dryer, there is a method of adjusting the oxygen concentration of the blown gas in the case of blowing the gas in the same way as the indirect heating method. It is also possible to adjust the oxygen concentration. In the present invention, it suffices if the oxygen concentration is within the above-mentioned preferable range, and a method of adjusting the oxygen concentration by a method other than those listed here may be used.

The temperature at which the heat treatment of the EVOH, more preferably the melting point of EVOH before heat treatment Ri Tm-30 (℃) over der as Tm (° C.), is Tm-25 (℃) above, Tm-20 ( It is particularly preferable that the temperature is higher than or equal to (° C). When heat treatment is performed at a temperature lower than Tm-30 (° C.), it may take a long time for EVOH to fully exhibit the effects of the present invention. If heat treatment is performed at a temperature equal to or higher than the melting point, EVOH is melted and subsequent handling is difficult.

  About heat processing time, it is 1 to 100 hours, It is more preferable that it is 2 to 90 hours, It is still more preferable that it is 3 to 80 hours, It is especially preferable that it is 4 to 75 hours. When the heat treatment time is less than 1 hour, EVOH having the effects of the present invention cannot be obtained. Performing heat treatment for a long time of 100 hours or more is not preferable from the viewpoint of productivity, and the hue and thermal stability of the obtained EVOH may be deteriorated.

When using those after drying as EVOH before thermal treatment, there is no problem even if the atmosphere oxygen concentration is high in the drying step, from the viewpoint of excellent in hue than the EVOH finally obtained after heat treatment is obtained Even in the drying step, it is more preferable to keep the atmospheric oxygen concentration within the above preferred range.

  When heat-treating the water-containing pellets, it may be a batch-type hot-air heat treatment machine (hot-air dryer), a fluidized hot-air heat treatment machine (hot-air dryer), or a heat treatment machine having a mechanism capable of keeping the atmosphere and temperature in the machine constant.

  In another embodiment relating to the method for producing EVOH of the present invention, heat treatment is performed in an extruder under an atmosphere having an oxygen concentration of 1000 ppm or less. The more preferable range of the oxygen concentration is the same as that described in the above embodiment.

  As a method for measuring the oxygen concentration in the extruder, an oxygen concentration suction hose is inserted into a hopper filled with resin, and the charged portion of the raw material resin is directly measured for oxygen concentration. Alternatively, an acrylic case or a polyethylene film is used to cover the entire extruder or to cover only the hopper where the resin is charged, and measure the oxygen concentration with an oximeter. Furthermore, the atmosphere is sampled with a syringe at the above-described location, and the oxygen concentration is measured using gas chromatography. Moreover, it does not matter if the measurement is performed by a general oxygen concentration measurement method.

As a general extruder, there are a single screw extruder and a twin screw extruder as a general one, but any type that can stay and knead at a temperature equal to or higher than the melting point may be used. A thing or a thing of a biaxial single axis tandem can also be used conveniently. The diameter of the extruder, L / D, screw configuration, and the like may be appropriately set according to the purpose such as the discharge amount to be obtained and the degree of heat treatment, and general ones are shown below.
Diameter 10mmφ ~ 200mmφ
L / D 5-75
Screw configuration Full flight (single axis)
Same direction mesh / different direction mesh (biaxial)
No vent, 1 or 2 may be used Compression ratio 2.0 to 4.0

The operating conditions of the extruder, such as the screw rotation speed, residence time, cylinder temperature, etc., may be appropriately set according to the purpose such as the target discharge amount and the degree of heat treatment. General operating conditions are as follows.
Number of rotation of the rotor 1 ~ 1200rpm
Kneading time 10-18000 seconds Extrusion temperature Tm + 10-Tm + 120 (° C.)
Nitrogen is continuously blown at a rate of 5 to 50 L / min in the vicinity of the inlet of the extruder (hopper part) so as not to insert oxygen into the extruder.

In order to sufficiently perform the esterification reaction, the heat treatment in the extruder can be repeated twice or more.

The raw material to be introduced into the press extruder, since the purpose et esterification, Ru with dry pellets in order to accelerate the reaction.

  As the EVOH before heat treatment used in the present invention, a conventionally known one can be used. A general method for producing EVOH is described below.

  EVOH is usually synthesized by saponification of an ethylene-vinyl ester copolymer, and generally vinyl acetate is used as the vinyl ester. Further, when ethylene and vinyl acetate are copolymerized, other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can be used in combination.

  The polymerization of ethylene and vinyl ester may be any of solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization, and may be either continuous type or batch type, for example, batch type solution polymerization. The polymerization conditions in this case are as follows.

Solvent: Alcohols are preferred, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl ester and ethylene-vinyl ester copolymer can be used. As alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable.
Catalyst: 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (4-methyl-2,4-dimethylvaleronitrile) ), 2,2′-azobis- (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis- (2-cyclopropylpropionitrile) and the like, and isobutyryl peroxide , Cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, t-butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, etc. Organic peroxide initiators and the like can be used.
Temperature; 20-90 ° C, preferably 40 ° C-70 ° C.
Time; 2-15 hours, preferably 3-11 hours.
Polymerization rate: 10 to 90%, preferably 30 to 80%, relative to the charged vinyl ester.
Resin content in the solution after polymerization; 5 to 85%, preferably 20 to 70%.
Ethylene content in the copolymer; 20-60 mol%, more preferably 22-55 mol%, optimally 24-50 mol%.

  In addition to ethylene and vinyl esters, monomers that can be copolymerized with these, for example, α-olefins such as propylene, isobutylene, α-octene, α-dodecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid, itacone Unsaturated acids such as acids or their anhydrides, salts, mono- or dialkyl esters, etc .; vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, γ-methacryloxypropylmethoxysilane Nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof; alkyl vinyl ethers, vinyl ketone, A small amount of N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like can be present together.

  After polymerization for a predetermined time, after reaching a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation, and then unreacted vinyl acetate is driven off. As a method for driving off unreacted vinyl acetate from the ethylene-vinyl acetate copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously fed at a constant rate from the upper part of the tower packed with Raschig rings, A method in which an organic solvent vapor such as methanol is blown from the bottom, a mixed vapor of an organic solvent such as methanol and unreacted vinyl acetate is distilled from the top of the tower, and the copolymer solution from which the unreacted vinyl acetate has been removed is removed from the bottom of the tower. Is adopted.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl acetate has been removed to saponify the vinyl acetate component in the copolymer. The saponification method can be either continuous or batch. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate or the like is used. For example, the saponification conditions in the case of a batch type are as follows.
The copolymer solution concentration: 10 to 50%.
Reaction temperature: 30-60 ° C.
Amount of catalyst used: 0.02 to 0.6 equivalent (per vinyl acetate component).
Time; 1-6 hours.
Although the degree of saponification after the saponification reaction varies depending on the purpose, it is preferably 80% or more of the vinyl acetate component, more preferably 95% or more, still more preferably 98% or more, and particularly preferably 99% or more. The degree of saponification can be arbitrarily adjusted according to the conditions.

  Since EVOH after the reaction contains an alkali catalyst, by-product salts, other impurities, etc., it is preferable to remove these by neutralization and washing as necessary.

  The resin composition of the present invention may be blended with EVOH having different degrees of polymerization, ethylene content and saponification, as long as the object of the present invention is not impaired. In addition, within the range that does not impair the object of the present invention, the resin composition may include other various plasticizers, stabilizers, surfactants, colorants, ultraviolet absorbers, slip agents, antistatic agents, drying agents, crosslinking agents, It is also possible to add appropriate amounts of reinforcing agents such as metal salts, fillers and various fibers.

  In addition, an appropriate amount of a thermoplastic resin other than the resin composition can be blended within a range that does not impair the object of the present invention. Examples of thermoplastic resins include various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene-propylene copolymers, copolymers of ethylene and α-olefins having 4 or more carbon atoms, polyolefins. And maleic anhydride copolymers, ethylene-vinyl ester copolymers, ethylene-acrylic ester copolymers, or modified polyolefins obtained by graft-modifying them with unsaturated carboxylic acids or their derivatives), various nylons (nylon -6, nylon-6,6, nylon-6 / 6,6 copolymer, etc.), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin.

  The obtained resin composition of the present invention is molded into various molded products such as films, sheets, containers, pipes, fibers and the like by melt molding. These molded products can be pulverized and molded again for reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers, and the like. As the melt molding method, extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding and the like are possible. The melting temperature varies depending on the melting point of the copolymer, but is preferably about 150 to 270 ° C.

  The resin composition of the present invention is a multilayer structure having at least one layer of a molded product such as the composition film or sheet of the present invention in addition to the production of a resin molded product having only the resin composition as a single layer as described above. Often used for practical use. The layer structure of the multilayer structure is represented by E / T, T / E / T, E / Ad / T, where E is the resin composition of the present invention, Ad is the adhesive resin, and T is the thermoplastic resin. Examples include T / Ad / E / Ad / T, but are not limited thereto. Each layer may be a single layer or may be a multilayer according to circumstances.

  The method for producing the multilayer structure shown above is not particularly limited. For example, a method in which a thermoplastic resin is melt-extruded on the molded product (film, sheet, etc.), conversely, a method in which the resin composition and another thermoplastic resin are co-extruded on a base material such as a thermoplastic resin, thermoplasticity A method of co-injecting a resin composition comprising a resin and EVOH, and further, forming a molded product obtained from the resin composition of the present invention and a film or sheet of another substrate into an organic titanium compound, an isocyanate compound, a polyester compound, etc. And a method of laminating using a known adhesive.

  The thermoplastic resin used is linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α-olefin copolymer. Polymers (α-olefins having 4 to 20 carbon atoms), homopolymers of olefins such as polybutene and polypentene or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, polyamide resins such as nylon-6 and nylon-6,6 , Polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl acetate resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, chlorinated polypropylene, and the like. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

  When laminating the resin composition of the present invention and the thermoplastic resin, an adhesive resin may be used, and the adhesive resin in this case is preferably an adhesive resin made of a carboxylic acid-modified polyolefin. Here, the carboxylic acid-modified polyolefin is a modified olefinic polymer containing a carboxyl group obtained by chemically (for example, addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer. Refers to coalescence. In addition, the olefin polymer is a polyolefin such as polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polypropylene, boribten, or the like, a comonomer (vinyl acetate, non-polymerizable) that can copolymerize the olefin and the olefin. Means a copolymer with a saturated carboxylic acid ester and the like, for example, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ethyl ester copolymer, and the like. Of these, linear low density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 5-55 wt%), ethylene-acrylic acid ethyl ester copolymer (acrylic acid ethyl ester content 8-35 wt. %), Linear low density polyethylene and ethylene-vinyl acetate copolymers are particularly preferred. Examples of the ethylenically unsaturated carboxylic acid or its anhydride include an ethylenically unsaturated monocarboxylic acid, its ester, an ethylenically unsaturated dicarboxylic acid, its mono or diester, and its anhydride. Among them, the ethylenically unsaturated dicarboxylic acid Anhydrides are preferred. Specific examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. Acid is preferred.

  The addition amount or graft amount (modification degree) of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer is 0.01 to 15% by weight, preferably 0.02 to 10% by weight, based on the olefin polymer. It is. The addition reaction and grafting reaction of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer can be obtained, for example, by radical polymerization in the presence of a solvent (such as xylene) or a catalyst (such as a peroxide). The melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g of the carboxylic acid-modified polyolefin thus obtained is preferably 0.2 to 30 g / 10 minutes, more preferably 0.5 to 10 g. / 10 minutes. These adhesive resins may be used alone or in combination of two or more.

  The method of coextrusion molding of the resin composition of the present invention and the thermoplastic resin is not particularly limited, and a multi-manifold merging method T-die method, a feed block merging method T-die method, an inflation method and the like are exemplified as suitable ones. . Further, the method of co-injection molding is not particularly limited, and a general method can be used. From the viewpoint that the effect of the present invention, which is excellent in moldability at high temperatures, can be particularly effectively exhibited, when a multilayer structure comprising the resin composition of the present invention and another thermoplastic resin is produced by coextrusion molding or co-injection molding In particular, it is particularly preferable to employ a manufacturing method in which the die temperature or nozzle temperature is 250 ° C. or higher. Even when performing such co-extrusion molding or co-injection molding at high temperature, there is no unevenness at the interface between the resin composition layer made of EVOH and the other thermoplastic resin layer, and the gel composition of the resin composition layer The significance of the present invention is also significant from the viewpoint of obtaining a multilayer structure with less appearance and good appearance.

By subjecting the coextruded multilayer structure or co-injection multilayer structure thus obtained to secondary processing, various molded products (films, sheets, tubes, bottles, etc.) can be obtained. Things.
(1) Multilayer co-stretched sheet or film obtained by stretching a multilayer structure (sheet or film, etc.) in a uniaxial or biaxial direction, or stretching and heat treatment in a biaxial direction (2) Multilayer structure (sheet, film, etc.) Multi-layer rolled sheet or film by rolling (3) Multi-layer structure (sheet or film, etc.) Multi-layer tray cup-shaped container (4) Multi-layer structure by vacuum forming, pressure forming, vacuum-pressure forming, etc. Bottles by stretch blow molding, etc. (pipe etc.), cup-like containers (5) Bottle containers by biaxial stretch blow molding, etc. from multilayer structures (parisons etc.) There are no particular restrictions on such secondary processing methods In addition, a known secondary processing method (such as blow molding) other than the above can also be employed.

  The co-extruded multilayer structure and co-injection multilayer structure obtained in this way have few fish eyes, are transparent, and have few streaks, so materials for food containers, such as deep-drawn containers, cup-shaped containers, bottles, etc. Is preferably used.

  The composition of the present invention has an effect of improving mechanical properties not only in melt molding but also in a porous body obtained by a molding method such as solution spinning. For example, after being dissolved in a solvent that is a good solvent for EVOH such as dimethyl sulfoxide or a mixed solvent that is a good solvent for EVOH such as water / methanol or water / propanol, it is dissolved in EVOH such as acetone, water, or methanol. On the other hand, it can also be suitably used for porous EVOH obtained by precipitation in a solvent that is a poor solvent.

Examples Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.

(1) Intrinsic viscosity 0.20 g of dry EVOH pellets as a sample is precisely weighed and dissolved in 40 mL of hydrous phenol (water / phenol = 15/85% by weight) at 60 ° C. for 4 hours to reach a temperature of 30 ° C. Then, it was measured with an Ostwald viscometer (t ₀ = 90 seconds), and the intrinsic viscosity [η] was determined by the following equation.
[Η] = (2 × (η _SP −ln η _r )) ^0.5 / C (L / g) Equation 2
η _SP = (t−t ₀ ) / t ₀ Formula 3
η _r = t / t ₀ Formula 4
C: EVOH concentration (g / L)
t ₀ : Blank falling seconds (s)
t: Number of seconds of falling of EVOH solution (s)

(2) Measurement of saponification degree (NMR method)
Dry EVOH pellets were ground by freeze grinding. The obtained pulverized EVOH was sieved with a sieve having a nominal size of 1 mm (conforming to standard sieve standard JIS Z-8801). 5 g of EVOH powder that passed through the above sieve was immersed in 100 g of ion-exchanged water, stirred at 85 ° C. for 4 hours, then drained and dried twice. Using the obtained powder EVOH after washing, NMR was measured under the following measurement conditions, and the degree of saponification was determined by the following analysis method.

Measurement conditions: Device name: JEOL Superconducting Nuclear Magnetic Resonance Device Lambda 500
Observation frequency: 500 MHz
Solvent: DMSO-d6
Polymer concentration: 4% by weight
Measurement temperature: 40 ° C and 95 ° C
Number of integrations: 600 times Pulse delay time: 3.836 seconds Sample rotation speed: 10-12 Hz
Pulse width (90 ° pulse): 6.75 μsec

・ Analysis method In the measurement at 40 ° C., a hydrogen peak in the water molecule is observed around 3.3 ppm, and the methine hydrogen peak of the vinyl alcohol unit of EVOH has a portion of 3.1 to 3.7 ppm. It overlapped. On the other hand, in the measurement at 95 ° C., the overlap generated at 40 ° C. is eliminated, but the hydrogen peak of the hydroxyl group of the vinyl alcohol unit of EVOH present in the vicinity of 4 to 4.5 ppm is methine of the vinyl alcohol unit of EVOH. It overlapped with a portion of 3.7 to 4 ppm of the hydrogen peak. That is, for the quantification of EVOH vinyl alcohol unit methine hydrogen (3.1-4 ppm), in order to avoid overlap with the hydrogen peak of water or hydroxyl group, about 3.1-3.7 ppm portion, The measurement data of ° C. was adopted, the measurement data of 40 ° C. was adopted for the portion of 3.7 to 4 ppm, and the total amount of the methine hydrogen was quantified as the total value thereof. It is known that the hydrogen peak of water or hydroxyl shifts to the high magnetic field side by increasing the measurement temperature.

Therefore, it analyzed using the measurement result of both 40 degreeC and 95 degreeC as follows. From the spectrum measured at 40 ° C., the integrated value (I ₁ ) of the peak of chemical shift of 3.7 to 4 ppm and the integrated value (I ₂ ) of the peak of chemical shift of 0.6 to 1.8 ppm are obtained. On the other hand, from the spectrum measured at 95 ° C., the integrated value (I ₃ ) of the peak of chemical shift of 3.1 to 3.7 ppm, the integrated value (I ₄ ) of the peak of chemical shift of 0.6 to 1.8 ppm and The integrated value (I ₅ ) of the peak of chemical shift of 1.9 to 2.1 ppm is determined. Here, the peak of chemical shift of 0.6 to 1.8 ppm is mainly derived from methylene hydrogen, and the peak of chemical shift of 1.9 to 2.1 ppm is in unsaponified vinyl acetate units. It is derived from methyl hydrogen. The saponification degree was calculated from these integral values by the following formula.

(3) Quantification of alkali metal salt (A) The dried EVOH pellets are quantitatively analyzed under the following conditions using an ion chromatography IC7000 manufactured by Yokogawa Electric Corporation, and the amount of alkali metal salt (A) is converted to a metal element value. Got in.
Ion chromatography measurement conditions:
Column: ICS-C25 manufactured by Yokogawa Electric Corporation
Eluent: aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid Measurement temperature: 40 ° C.
Eluent flow rate: 1 mL / min.
Sample injection amount: 50 μL

(4) Quantitative determination of phosphoric acid compound (B) 1.0 g of dry EVOH resin composition powder was put into a conical stoppered Erlenmeyer flask, and 15 ml of concentrated nitric acid and 4 ml of concentrated acid were added, and a cooling condenser was attached. Thermal decomposition at ℃. The mixture was heated until the nitric acid was sufficiently volatilized and white smoke was generated, then cooled, and the solution was diluted to a 50 ml volumetric flask. The solution was quantitatively analyzed at an observation wavelength of 214.914 nm using an ICP emission spectroscopic analyzer Optima 4300 DV manufactured by PerkinElmer Japan. For the determination, a calibration curve prepared by diluting a phosphate ion standard solution manufactured by Wako Pure Chemical Industries, Ltd. was used. From the amount of phosphoric acid thus obtained, the amount of phosphoric acid compound (C) was obtained in terms of phosphorus element.

(5) Measurement of moisture content of water-containing EVOH pellets Using a HR73 halogen moisture content analyzer manufactured by METTLER, the moisture content of EVOH pellets was measured under the conditions of a drying temperature of 180 ° C, a drying time of 20 minutes, and a sample amount of about 10 g.

(6) Oxygen concentration measurement Oxygen concentration measurement was performed under standard conditions using ISM-3 manufactured by DANSENSOR.
As a method for measuring the oxygen concentration in the dryer, the tip of the suction hose of ISM-3 was inserted from the packing portion on the front surface of the dryer, and the oxygen concentration inside the dryer was measured.
As a method for measuring the oxygen concentration in the extruder, the tip of the suction hose of ISM-3 was inserted into the hopper, and the oxygen concentration about 3 cm above the screw was measured.

(7) Single-layer film formation test The obtained dried EVOH pellets were manufactured by Toyo Seiki Seisakusho Co., Ltd. 20 mm extruder D2020 (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight ) Was used under the following conditions to obtain a single layer film.
Extrusion temperature: C1 / C2 / C3 / Die = 175/200/220/220 ° C.
Screw rotation speed: 40rpm
Discharge rate: 1.3 kg / hr
Take-up roll temperature: 80 ° C
Take-up roll speed: 3.1 m / min.
Film thickness: 20 μm

(7-a) Coloring resistance The monolayer film produced by the above method was wound around a paper tube until the film end face was sufficiently visible, and the degree of coloration of the film end face was determined with the naked eye as follows.
Judgment: Standard A: No coloring B: Slightly yellow C: Yellowing

(7-b) 72 hr-long run properties 72 hours after the start of single-layer film formation, the film was sampled, and the gel-like spots in the film (those of about 100 μm or more that can be confirmed with the naked eye) were counted.
The number of bumps was converted to the number per 1.0 m ² and judged as follows.
Determination: Standard A: Less than 20 B: 20 or more and less than 40 C: 40 or more and less than 60 D: 60 or more

(7-c) Measurement of tensile yield point strength The prepared single-layer film was conditioned for 7 days in an atmosphere of 23 ° C. and 50% RH, and a strip-shaped piece having a width of 15 mm was prepared. Using this film sample, tensile yield point strength was measured with an autograph AGS-H type manufactured by Shimadzu Corporation under conditions of a chuck interval of 50 mm and a tensile speed of 500 mm / min. The measurement was performed for each 10 samples, and the average value was obtained.

(7-d) Streak characteristics The single-layer film produced by the above method was wound around a paper tube, and the streak (film streaks) of the film was determined with the naked eye as follows.
Judgment: Standard A: Less B: Normal C: Many

3.3 kg of water-containing pellets with an ethylene content of 32 mol%, a saponification degree of 99.9%, and an intrinsic viscosity of 0.085 l / g were acetic acid 0.4 g / L, potassium hydrogen carbonate 0.14 g / L, potassium dihydrogen phosphate It was immersed and stirred at 27 ° C. for 6 hours in 27 L of an aqueous solution containing 0.11 g / L. Thereafter, the solution was drained to obtain hydrous pellets. The hydrous pellets were put into a hot air dryer (DN6101 manufactured by Yamato Kagaku), nitrogen was blown in at a rate of 30 L / min for 3 hours, and the atmosphere in the hot air dryer (DN6101 manufactured by Yamato Kagaku) was set to nitrogen. Then, the hot air dryer (DN6101 made from Yamato Scientific) was heated up to 80 degreeC, and it dried in nitrogen atmosphere for 16 hours. The water content of the water-containing pellets at this time was 0.25%, and Tm was 183 degrees.
EVOH was heat-treated at 160 ° C. for 48 hours under a nitrogen atmosphere to obtain EVOH. At that time, the oxygen concentration in the hot air dryer (DN6101 manufactured by Yamato Kagaku) was measured by ISM-3 manufactured by DANSENSOR and found to be 10 ppm or less.

The intrinsic viscosity (η _F ) of the obtained heat-treated EVOH pellets was 0.108 l / g. Moreover, the intrinsic viscosity (η ₀ ) of the obtained dried EVOH pellets after alkali treatment was 0.092 l / g, and η ₀ / η _F was 0.85.

  The alkali metal salt (A) in the obtained heat treated EVOH pellets was potassium, the content of the alkali metal salt (A) was 130 ppm in terms of metal element, and phosphoric acid was 12 ppm in terms of phosphorus element. The MFR of the heat-treated EVOH pellets was 1.6 g / 10 min. (Under 190 ° C. and 2160 g load).

  Using the obtained heat-treated EVOH pellets, a single-layer film was produced according to the above-described method, and tests for coloring resistance and long run property were performed. The evaluation result of EVOH coloring resistance and 72-hour long run property of this example was A.

  Using the heat-treated EVOH pellets obtained, a single-layer film was prepared according to the above-described method, and after adjusting the humidity for 7 days in an atmosphere of 23 ° C. and 50% RH, the strip having a width of 15 mm was measured. Shaped sections were prepared. Using the film sample, the tensile strength at break in the MD direction was measured with an autograph AGS-H manufactured by Shimadzu Corporation under the conditions of a chuck interval of 50 mm and a tensile speed of 500 mm / min. The measurement was performed for 10 samples each, and the average value was obtained. As a result, the tensile strength at break was 10.0 kgf / mm.

  The single layer film produced by the above method was wound around a paper tube, and the streak (film streaks) of the film was determined with the naked eye. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

  Except for using water-containing pellets having an intrinsic viscosity of 0.113 l / g, high-viscosity EVOH pellets were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

  EVOH pellets were produced in the same manner as in Example 1 except that water-containing pellets having an intrinsic viscosity of 0.060 l / g were used and the heat treatment time was changed from 48 hours to 72 hours. Evaluation was performed in the same manner. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

  A high-viscosity EVOH pellet was prepared in the same manner as in Example 1 except that a water-containing pellet having an ethylene content of 24 mol% and an intrinsic viscosity of 0.113 l / g was used. Evaluation was performed. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

  Using water-containing pellets having an ethylene content of 47 mol% and an intrinsic viscosity of 0.085 l / g, the treatment liquid concentrations of potassium hydrogen carbonate and potassium dihydrogen phosphate during acid treatment were changed as shown in Table 1. Further, except that the heat treatment temperature and time were changed, high-viscosity EVOH pellets were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

  After the acid treatment, when the dehydrated water-containing pellets are put into a hot air dryer (DN6101 made by Yamato Kagaku) and heat treatment is performed, the gas to be blown is changed to a mixed gas of nitrogen and air, except that the heat treatment time is changed. For example, high-viscosity EVOH pellets were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. It was 700 ppm as a result of measuring the oxygen concentration in the hot air dryer (DN6101 made by Yamato Scientific) at the time of heat processing. Table 1 shows the composition and heat treatment conditions of the high-viscosity EVOH resin composition, and Table 2 shows the evaluation results.

  When the same water-containing pellets as in Example 1 which had been acid-treated and drained were put into a hot air dryer (DN6101 manufactured by Yamato Kagaku) and subjected to heat treatment, dew point air was blown at a rate of 30 L / min and dried at 80 ° C. for 16 hours. Then, it dried at 105 degreeC for 16 hours. The moisture content of the obtained dried pellet was 0.25%. Then, nitrogen was blown into the hot air dryer (Yamato Scientific DN 6101) at a rate of 30 L / min for 3 hours, and the atmosphere of the hot air dryer (Yamato Scientific DN 6101) was changed to a nitrogen atmosphere. Thereafter, the dried pellets were heat treated at a heat treatment temperature of 160 ° C. for 48 hours to obtain EVOH. Thereafter, the oxygen concentration in the hot air dryer (DN 6101 manufactured by Yamato Kagaku) was measured and found to be 10 ppm or less. The obtained heat-treated pellet was evaluated in the same manner as in Example 1. The composition of the EVOH resin composition is shown in Table 1, and the evaluation results are shown in Table 2.

The same hydrous pellets as in Example 1 were acid-treated and then drained, put into a hot air dryer (DN6101 manufactured by Yamato Kagaku), and dew point air was blown at a rate of 30 L / min for 3 hours, and a hot air dryer (DN6101 manufactured by Yamato Scientific) was used. The atmosphere in) was air. Thereafter, the temperature was raised to 80 ° C. with a hot air dryer (DN 6101 manufactured by Yamato Kagaku) and dried in an air atmosphere for 16 hours. Furthermore, EVOH was heat-treated at 105 ° C. for 16 hours in an air atmosphere to produce dry pellets. The moisture content of the obtained dried pellet was 0.25%.

The dried pellets were heat-treated using a single screw extruder under the following conditions to produce heat-treated pellets.

D (mm) = 40φ
L / D = 26
Nitrogen is continuously blown into the hopper at a rate of 10 L / min. Extrusion temperature: C1 / C2 / C3 / AD / Die = 200/250/250/250/250 ° C.
Screw rotation speed: 1.5rpm
Residence time: 10000 seconds The heat-treated pellets thus obtained were evaluated in the same manner as in Example 1. The composition of the EVOH resin composition is shown in Table 1, and the evaluation results are shown in Table 2.

Comparative Example 1
The water-containing pellets used in Example 1 were acid-treated and then drained, put into a hot air dryer (DN6101 manufactured by Yamato Kagaku), blown dew point air at a rate of 30 L / min for 3 hours, and the atmosphere in the inert oven was air It was. Thereafter, the inert oven was heated to 80 ° C., dried in an air atmosphere for 16 hours, and then EVOH was heat-treated at 105 ° C. for 16 hours in an air atmosphere to produce EVOH, which was evaluated in the same manner as in Example 1. Went. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

Comparative Example 2
EVOH pellets were produced in the same manner as in Comparative Example 1 except that hydrous pellets having an intrinsic viscosity of 0.113 l / g were used, and evaluation was performed in the same manner as in Comparative Example 1. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

Comparative Example 3
EVOH pellets were produced in the same manner as in Comparative Example 1 except that hydrous pellets having an intrinsic viscosity of 0.060 l / g were used, and evaluation was performed in the same manner as in Example 1. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

Comparative Example 4
EVOH pellets were prepared in the same manner as in Comparative Example 1 except that water-containing pellets having an ethylene content of 24 mol% and an intrinsic viscosity of 0.113 l / g were used, and evaluation was performed in the same manner as in Example 1. It was. Table 1 shows the composition of the EVOH resin composition and heat treatment conditions, and Table 2 shows the evaluation results.

Comparative Example 5
EVOH pellets were prepared in the same manner as in Comparative Example 1 except that water-containing pellets having an ethylene content of 47 mol% and an intrinsic viscosity of 0.085 l / g were used. It was. Table 1 shows the composition of the EVOH resin composition, the heat treatment conditions are shown in Table 1, and the evaluation results are shown in Table 2.

Comparative Example 6
A high-viscosity EVOH pellet was prepared in the same manner as in Example 1 except that a water-containing pellet having an intrinsic viscosity of 0.040 l / g was used and the drying time was changed. Evaluation was performed. Table 1 shows the composition and heat treatment conditions of the high-viscosity EVOH resin composition, and Table 2 shows the evaluation results.

Comparative Example 7
Except for changing the heat treatment time by changing the gas to be blown to a mixed gas of nitrogen and air when heat treatment is performed by placing the dehydrated hydrous pellets after acid treatment into a hot air dryer (DN6101 made by Yamato Kagaku). A high-viscosity EVOH pellet was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. Table 1 shows the composition and heat treatment conditions of the high-viscosity EVOH resin composition, and Table 2 shows the evaluation results. It was 1500 ppm as a result of measuring the oxygen concentration in the hot air dryer (DN6101 made by Yamato Scientific) at the time of heat processing.

Comparative Example 8
The same hydrous pellets as in Example 1 were acid-treated and then drained, put into a hot air dryer (DN6101 manufactured by Yamato Kagaku), and dew point air was blown at a rate of 30 L / min for 3 hours, and a hot air dryer (DN6101 manufactured by Yamato Scientific) was used. The atmosphere in) was air. Thereafter, the temperature was raised to 80 ° C. with a hot air dryer (DN 6101 manufactured by Yamato Kagaku) and dried in an air atmosphere for 16 hours. Furthermore, EVOH was heat-treated at 105 ° C. for 16 hours in an air atmosphere to produce dry pellets. The moisture content of the obtained dried pellet was 0.25%.

The dried pellets were heat-treated using a single screw extruder under the following conditions to produce heat-treated pellets.

D (mm) = 40φ
L / D = 26
Extrusion temperature without blowing nitrogen into the hopper: C1 / C2 / C3 / AD / Die = 200/250/250/250/250 ° C.
Screw rotation speed: 90rpm
Residence time: 180 seconds The heat-treated pellets thus obtained were evaluated in the same manner as in Example 1. The composition of the EVOH resin composition is shown in Table 1, and the evaluation results are shown in Table 2.

Claims (3)

Ethylene content of 20 to 60 mol%, saponification degree of 99.0 mol%, an intrinsic viscosity eta ₀ after the intrinsic viscosity eta _F and alkali treatment satisfies the following equation, and an oxygen concentration is below 1000ppm atmosphere An ethylene-vinyl alcohol copolymer that has been subjected to heat treatment for 1 to 100 hours at
The temperature at which the heat treatment is performed is not lower than the melting point of the ethylene-vinyl alcohol copolymer before the heat treatment is -30 ° C,
An ethylene-vinyl alcohol copolymer having a water content of 0.25% or less before the heat treatment .
0.5 <η ₀ / η _F <0.95
(Here, alkali treatment means that 4 g of ethylene-vinyl alcohol copolymer is placed in a 300 mL Erlenmeyer flask, 20 mL of 1N aqueous sodium hydroxide solution and 30 g of normal propyl alcohol are added, and then a water-cooled condenser is attached. (Vacuum degassing is repeated 5 times, followed by heating and stirring at 80 ° C. for 3 hours to dissolve and then driving the reaction at 60 ° C. for another 3 hours.)   An ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the ethylene-vinyl alcohol copolymer contains 10 to 1000 ppm of an alkali metal salt in terms of the metal.   The ethylene-vinyl alcohol copolymer resin according to claim 1, which contains an alkali metal salt in an amount of 10 to 1000 ppm and a phosphate in an amount of 5 to 1000 ppm in terms of the metal. Composition.