JP5307960B2 - Ethylene-vinyl alcohol copolymer resin composition having improved long run properties and molded article thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition which scarcely generates voids, has an excellent appearance, hardly adheres to dies, has a good long run property and a good self-purging property, and comprises a substantially non-colored ethylene vinyl alcohol copolymer, and to obtain a multi-layered structure using the same. SOLUTION: This ethylene-vinyl alcohol copolymer resin composition whose intrinsic viscosity [&eta;] changes satisfy the following expressions (1) to (3): 0.05<=[&eta;]0<=0.2 (1), 0.12<=[&eta;]10/[&eta;]0<=0.6 (2), and 0.1<=[&eta;]60/[&eta;]0<=0.8 (3), wherein [&eta;]0: an intrinsic viscosity before a thermal treatment, [&eta;]10: an intrinsic viscosity after 10 hr from the start of the thermal treatment, and [&eta;]60: an intrinsic viscosity after 60 hr from the start of the thermal treatment, when thermally treated at 220 deg.C under a nitrogen atmosphere, which contains (A) carboxylic acids in an amount of 0.05 to 5 &mu;mol/g, in which the ratio of the total content (&mu;mol/g) of (a) the carboxylic acid having the mol.wt. of >=70 and its salt to the total content (&mu;mol/g) of (A) the carboxylic acid and their salts is >=0.1, and which has (B) an alkaline earth metal salt in an amount of 2 to 25 &mu;mol/g converted into the metal.

Description

  The present invention relates to a resin composition comprising an ethylene-vinyl alcohol copolymer with little generation of voids, excellent appearance, less die adhesion, long run property and good self-purge property, and little coloration, and a multilayer structure using the same About the body.

  An ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is a useful polymer material excellent in various gas shielding properties such as oxygen, oil resistance, non-charging property, mechanical strength, and the like. It is molded into containers and widely used as various packaging materials. In such molding, since melt molding is usually performed, EVOH has a long run property during melt molding (a molded product free from fish eyes and streaks can be obtained even during long-time molding), and appearance (generation of gels and blisters). A molding that cannot be seen) is required.

  However, since EVOH has a chemically relatively active hydroxyl group in the molecule, oxidation and cross-linking reactions occur inside an extruder that has almost no oxygen in a high-temperature molten state. It accumulates inside the machine and tends to cause problems due to thermal stability such as streaks and gels.

  In order to improve such a problem, a method of adding a small amount of acid / metal salt to EVOH is known. In order to improve the long run property and the appearance typified by gel and butts, (1) periodic rule 0.0005 to 0.05% by weight (metal equivalent) of a metal salt belonging to Table 2; an acid having a pKa of 3.5 or higher and a boiling point of 180 ° C. or higher; 0.002 to 0.2% by weight; and a pKa of 3.5 or higher. An EVOH composition containing 0.01 to 0.2% by weight of an acid having a boiling point of 120 ° C. or lower and exhibiting specific flow characteristics is disclosed (Japanese Patent Laid-Open No. 64-66262). Moreover, as EVOH with little coloration and less occurrence of molding during molding and excellent adhesion, (2) hydroxycarboxylic acid and / or its salt is 100-5000 ppm in terms of hydroxycarboxylic acid, and alkali metal salt is in terms of metal An EVOH composition containing 50 to 500 ppm and an alkaline earth metal salt in an amount of 20 to 200 ppm in terms of metal is disclosed (JP-A-10-67898). Furthermore, as EVOH showing improved stability against the formation of oxidative gels at high temperatures, (3) at least one monovalent or divalent metal of an aliphatic carboxylic acid having 3 to 9 carbon atoms EVOH is disclosed which consists essentially of about 0.01 to about 0.5 weight percent salt and about 0.05 to about 0.5 parts by weight of at least one hindered phenolic antioxidant. (JP-A-4-227744).

  In the disclosed technologies (1) to (3) as described above, the long run property and appearance of EVOH are improved as compared to the previous technologies. However, when a part of the resin tends to stay in the molding machine for a long time, such as when performing a continuous operation for an extremely long time, even if EVOH disclosed in the above disclosed technique is used, crosslinking and thickening are eventually performed. To gelation. For this reason, even in a field where a very high long-running property is required, development of EVOH which is less likely to generate gels and bunches and has excellent coloring resistance and appearance is required.

  In order to suppress the occurrence of gels and blisters, it is desirable not to increase the melt viscosity of the resin composition. However, when the melt viscosity is too low, there is a problem that a molded product such as a film cannot be obtained. In such a case, even if a film is obtained by selecting the molding conditions, fine bubbles called voids are generated when the degree of light is low due to the decomposition gas generated by the decomposition of EVOH. Appears on the top and the appearance is significantly poor. When this void is small, it looks like a gel at first glance, but the gel bulges in a convex shape on the film, whereas the void is concaved in a concave shape so that it can be easily distinguished.

  When production is temporarily suspended on weekends, etc., EVOH is usually purged from the inside of the molding machine with polyethylene or the like, and the switch is turned off, but a small amount of EVOH remains in the molding machine, and this is the process of raising and lowering the temperature of the equipment. There is a problem that it deteriorates and becomes a gel when the molding machine is restarted, which deteriorates the appearance of the film and sheet and takes time until the appearance is restored to a normal state. (This is referred to as self-purge failure.)

Problems to be solved by the invention

  Based on the above, a resin composition comprising an ethylene-vinyl alcohol copolymer that is extremely excellent in long run properties, has no voids or holes, has an excellent appearance, has good self-purge properties, and has little coloring, and uses the same. There was a need for a multilayered structure.

Means for solving the problem

[Means for Solving the Problems]
The problem shown above is that the change in intrinsic viscosity [η] when heat-treated at 220 ° C. in a nitrogen atmosphere satisfies the following formulas (1) to (3), and the carboxylic acid (A) is changed to 0.05 to The ethylene content is 32 to 44 mol, characterized by containing 5 μmol / g and the alkaline earth metal salt (B) in a metal element equivalent of 6.36 to 25 μmol / g and satisfying the following formula (4): %, An ethylene-vinyl alcohol copolymer resin composition having a saponification degree of 80% or more.
0.05 ≦ [η] 0 ≦ 0.2 (1)
0.12 ≦ [η] 10 / [η] 0 ≦ 0.6 (2)
0.1 ≦ [η] 60 / [η] 0 ≦ 0.8 (3)
0.95 ≦ (a ′ ) / (A ′ ) ≦ 1.0 (4)
However,
[Η] 0: Intrinsic viscosity of ethylene-vinyl alcohol copolymer before heat treatment [η] 10: Intrinsic viscosity of ethylene-vinyl alcohol copolymer resin composition 10 hours after start of heat treatment [η] 60: Intrinsic viscosity (A ′ ) of ethylene-vinyl alcohol copolymer resin composition 60 hours after start of heat treatment: total content of carboxylic acid (A) and its salt (μmol / g)
(A ′ ): content of carboxylic acid (a) having a molecular weight of 70 or more and not more than the molecular weight of lauric acid and its salt (μmol / g)

That is, in the present invention, the change in intrinsic viscosity [η] when heat-treated at 220 ° C. in a nitrogen atmosphere satisfies the following formulas (1) to (3), and the carboxylic acid (A) is 0.05 to 5 μmol / g and an alkaline earth metal salt (B) in an amount of 6.36 to 25 μmol / g in terms of metal element and satisfying the following formula (4): an ethylene content of 32 to 44 mol%, The present invention relates to an ethylene-vinyl alcohol copolymer resin composition having a saponification degree of 80% or more.
0.05 ≦ [η] 0 ≦ 0.2 (1)
0.12 ≦ [η] 10 / [η] 0 ≦ 0.6 (2)
0.1 ≦ [η] 60 / [η] 0 ≦ 0.8 (3)
0.95 ≦ (a ′ ) / (A ′ ) ≦ 1.0 (4)
However,
[Η] 0: Intrinsic viscosity of ethylene-vinyl alcohol copolymer before heat treatment [η] 10: Intrinsic viscosity of ethylene-vinyl alcohol copolymer resin composition 10 hours after start of heat treatment [η] 60: Intrinsic viscosity (A ′ ) of ethylene-vinyl alcohol copolymer resin composition 60 hours after start of heat treatment: total content of carboxylic acid (A) and its salt (μmol / g)
(A ′ ): content of carboxylic acid (a) having a molecular weight of 70 or more and not more than the molecular weight of lauric acid and its salt (μmol / g)

In a more preferred embodiment, the resin composition of the present invention satisfies the following formulas (1 ′) to (3 ′) when the intrinsic viscosity [η] is heat-treated at 220 ° C. in a nitrogen atmosphere. wherein 0.05~4μmol / g of acid (a), the total content of the carboxylic acid (a) and its salts (μmol / g) molecular weight of 70 or more with respect to and molecular weight less that the carboxylic acid of lauric acid (a) and An ethylene-vinyl alcohol copolymer resin having a salt content (μmol / g) ratio of 0.1 or more and containing an alkaline earth metal salt (B) in an amount of 2.5 to 20 μmol / g in terms of metal. It is a composition.
0.06 ≤ [η] 0 ≤ 0.17 (1 ')
0.15 ≤ [η] 10 / [η] 0 ≤ 0.5 (2 ')
0.12 ≤ [η] 60 / [η] 0 ≤ 0.65 (3 ')

In a preferred embodiment, the resin composition of the present invention satisfies the following formula (5).
0.2 ≦ [η] 60 / [η] 10 ≦ 2.5 (5)
More preferably, the resin composition of the present invention satisfies the following formula (5 ′).
0.3 ≦ [η] 60 / [η] 10 ≦ 2 (5 ')

In a preferred embodiment, the resin composition of the present invention has an ethylene content of 30 to 50 mol%, and the alkaline earth metal salt (B) is represented by the following formulas (6) to (8). Contained within the range of M _II .
^{X = 0.0257 x E 2 - 2.31} x E + 54.7 (6)
^{Y = 0.0372 x E 2 - 2.43} x E + 47.7 (7)
X ≤ M _II ≤ Y (8)
However,
E: Ethylene content of ethylene-vinyl alcohol copolymer (mol%)
M _II : Content of alkaline earth metal salt (B) (metal conversion value: μmol / g)
More preferably, the resin composition of the present invention contains the alkaline earth metal salt (B) within the range of M _II represented by the following formulas (6 ′) to (8 ′).
^{X '= 0.0286 x E 2 -} 2.55 x E + 60.1 (6')
^{Y '= 0.0229 x E 2 -} 1.46 x E + 31.2 (7')
X '≤ M _II ≤ Y' (8 ')

  In a preferred embodiment, the resin composition of the present invention has a weight loss rate of 5% or more and 35% or less after 2 hours from the start of heating in a nitrogen atmosphere at 230 ° C.

In a preferred embodiment , the carboxylic acid (a) having a molecular weight of 70 or more and a molecular weight of lauric acid or less is lactic acid.

  In a preferred embodiment, the resin composition of the present invention contains the boron compound (D) in an amount of 50 to 2000 ppm in terms of boron.

  In a preferred embodiment, the resin composition of the present invention contains 10 to 500 ppm of the phosphoric acid compound (E) in terms of phosphate radical.

  The present invention relates to a molded article comprising the above resin composition.

  The present invention also relates to a multilayer structure including at least one layer composed of the resin composition.

  As EVOH used for this invention, what is obtained by saponifying an ethylene-vinyl ester copolymer is preferable, and ethylene content is 20-70 mol% suitably among them. From the viewpoint of obtaining a molded article having excellent gas barrier properties and melt moldability, the ethylene content is more preferably 25 to 65 mol%. Further, from the viewpoint of maintaining extremely high long-run property and self-purge property while effectively suppressing the generation of voids and the like, the lower limit of the ethylene content is more preferably 30 mol% or more, and more preferably It is 33 mol% or more, optimally 36 mol% or more. From the viewpoint of gas barrier properties, the upper limit of the ethylene content is preferably 65 mol% or less, more preferably 60 mol% or less, and most preferably 50 mol% or less. Furthermore, the saponification degree of the vinyl ester component is preferably 80% or more, and more preferably 95% or more, and still more preferably 99% or more from the viewpoint of obtaining a molded article having excellent gas barrier properties. When ethylene content exceeds 70 mol%, there exists a possibility that barrier property, printability, etc. may be insufficient. On the other hand, if the degree of saponification is less than 80%, the barrier property, thermal stability and moisture resistance may be deteriorated.

  As the vinyl ester copolymerized with ethylene, vinyl acetate is particularly suitable, but other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can also be used in combination. Moreover, EVOH can contain 0.0002-0.2 mol% of vinyl silane compounds as a copolymerization component. Here, examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

  The EVOH production method will be specifically described below. The polymerization of ethylene and vinyl ester is not limited to solution polymerization, and may be any of solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, and may be either continuous or batch-type, For example, polymerization conditions in the case of batch solution polymerization 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 other azonitrile initiators, isobutyryl peroxide, cumylperoxyneo Organic peroxides such as decanoate, diisopropyl peroxycarbonate, di-n-propyl peroxydicarbonate, t-butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide, t-butyl hydroperoxide An initiator or 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%.

  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 .; Nitriles such as acrylonitrile and methacrylonitrile; Amides such as acrylamide and methacrylamide; Ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfone An olefin sulfonic acid such as an acid or a salt thereof; alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride and the like may be present in a small amount.

  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 ester is driven out. As a method for driving off the unreacted vinyl ester from the ethylene-vinyl ester 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 column filled 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 ester is distilled from the top of the tower, and the copolymer solution from which the unreacted vinyl ester has been removed is removed from the bottom of the tower, etc. Is adopted.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester 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 ester 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 ester component, more preferably 95% or more, and still more preferably 99% or more. The degree of saponification can be arbitrarily adjusted according to the conditions.

  Since the ethylene-vinyl alcohol copolymer (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.

  Method of containing ethylene-vinyl alcohol copolymer with carboxylic acid (A), alkaline earth metal salt (B) and, if necessary, alkali metal salt (C), boron compound (D) and phosphoric acid compound (E) Is not particularly limited. For example, a method of immersing the saponified product in a solution in which the compound is dissolved, a method of melting the saponified product and mixing the compound, a method of dissolving the saponified product in an appropriate solvent and mixing the compound , Etc. are exemplified.

  In the case of a method in which an ethylene-vinyl alcohol copolymer is immersed in a solution of the above compound and each compound is added, the operation can be carried out by either a batch method or a continuous method. In this case, the shape of the saponified product may be any shape such as powder, granule, sphere, or cylindrical pellet. In addition, the concentration of each of the above compounds is not particularly limited, and the solvent of the solution is not particularly limited. However, an aqueous solution is preferable for reasons of handling. The preferable range of the immersion time varies depending on the form of the ethylene-vinyl alcohol copolymer, 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 above various compounds in the solution is not particularly limited, and may be immersed in a plurality of solutions, or may be performed at a time, but may be performed at a time from the point of simplification of the process. preferable. When the treatment is performed by immersing in the solution as described above, the final drying is performed to obtain the target ethylene-vinyl alcohol copolymer resin composition.

The resin composition of the present invention is greatly characterized in that the change in intrinsic viscosity [η] when heat-treated at 220 ° C. in a nitrogen atmosphere satisfies the following formulas (1) to (3).
0.05 ≤ [η] 0 ≤ 0.2 (1)
0.12 ≤ [η] 10 / [η] 0 ≤ 0.6 (2)
0.1 ≤ [η] 60 / [η] 0 ≤ 0.8 (3)
However,
[η] 0: Intrinsic viscosity before heat treatment
[η] 10: Intrinsic viscosity 10 hours after the start of heat treatment
[η] 60: Intrinsic viscosity 60 hours after the start of heat treatment

The above formulas (1) to (3) are more preferably
0.06 ≤ [η] 0 ≤ 0.17 (1 ')
0.15 ≤ [η] 10 / [η] 0 ≤ 0.5 (2 ')
0.12 ≤ [η] 60 / [η] 0 ≤ 0.65 (3 ')
And more preferably
0.07 ≦ [η] 0 ≦ 0.15 (1 ”)
0.2 ≤ [η] 10 / [η] 0 ≤ 0.45 (2 ")
0.15 ≦ [η] 60 / [η] 0 ≦ 0.5 (3 ”)
It is.

  [η] 0 represents the intrinsic viscosity of EVOH before heat treatment. When [η] 0 is less than 0.05 or exceeds 0.2, EVOH moldability deteriorates.

  [η] 10 / [η] 0 represents the ratio of the intrinsic viscosity of EVOH before heat treatment to the intrinsic viscosity of EVOH 10 hours after the start of heating. When the ratio is less than 0.12, that is, when the intrinsic viscosity of EVOH rapidly decreases, the appearance of the molded product is deteriorated by the gas generated by the rapid decomposition of EVOH. In particular, when the molded product is a film or the like, problems such as voids and holes are generated. On the other hand, when the ratio exceeds 0.6, the intrinsic viscosity of EVOH is not sufficiently lowered, and the improvement effect of the long run property and the self purge property is unsatisfactory.

  [η] 60 / [η] 0 represents the ratio between the intrinsic viscosity of EVOH before heat treatment and the intrinsic viscosity of EVOH 60 hours after the start of heating. When the ratio is within the range of the above formula (3), the resin is not gelled even when the molding machine is operated continuously for a long time with a molding machine with many residence times and a long residence time. Easy to be pushed out. For this reason, generation | occurrence | production of the gel of the molded object by the heat-degraded resin, etc. can be suppressed, and it is possible to obtain the molded article excellent in the external appearance. When [η] 60 / [η] 0 is less than 0.1, the appearance of the molded product deteriorates due to gas generated by rapid decomposition of EVOH. In particular, when the molded product is a film or the like, problems such as voids and holes are generated. On the other hand, when the ratio exceeds 0.8, the EVOH intrinsic viscosity is not sufficiently lowered, and the EVOH resin staying in the molding machine is likely to gel when continuously operated for a long time. In addition, the self-purge improvement effect is unsatisfactory.

Moreover, it is preferable that the resin composition of this invention satisfy | fills the following Formula (5).
0.2 ≤ [η] 60 / [η] 10 ≤ 2.5 (5)
The above formula (5) is more preferably
0.3 ≤ [η] 60 / [η] 10 ≤ 2 (5 ')
And more preferably
0.5 ≤ [η] 60 / [η] 10 ≤ 1.7 (5 ")
It is.

  By satisfying the above formula (5), a change in the intrinsic viscosity is small even during long-time molding, and a resin composition excellent in moldability can be obtained. That is, during a long continuous operation, an increase in the difference in viscosity between the resin present at the staying location and the resin flowing through the flow path is suppressed, so that it is possible to prevent abnormal resin flow in the molding machine. As a result, it becomes possible to stably produce the molded product. When [η] 60 / [η] 10 is less than 0.2, the appearance of the molded product may be deteriorated by gas generated by rapid decomposition of EVOH. In particular, when the molded product is a film or the like, problems such as voids and holes may occur. On the other hand, when the ratio exceeds 2.5, the effect of improving the long run property and the self purge property may be unsatisfactory.

  Moreover, the resin composition of this invention contains 0.05-5 micromol / g of carboxylic acid (A). Examples of the carboxylic acid (A) used in the resin composition of the present invention include saturated aliphatic carboxylic acids such as acetic acid and propionic acid, unsaturated aliphatic carboxylic acids such as oleic acid, hydroxycarboxylic acids such as glycolic acid and lactic acid, Examples thereof include aromatic carboxylic acids such as benzoic acid, and the pKa at 25 ° C. is preferably 3.5 or more. If the pKa at 25 ° C. is less than 3.5, it may be difficult to control the pH of the resin composition comprising EVOH, and the coloring resistance and interlayer adhesion may be unsatisfactory.

  The carboxylic acid (A) used in the resin composition of the present invention includes a carboxylic acid (a) having a molecular weight of 70 or more, and has a molecular weight of 70 with respect to the total content (μmol / g) of the carboxylic acid (A) and a salt thereof. It is essential that the ratio of the carboxylic acid (a) and the salt content (μmol / g) is 0.1 or more. Examples of the carboxylic acid (a) having a molecular weight of 70 or more used in the present invention include succinic acid, adipic acid, benzoic acid, capric acid, lauric acid, glycolic acid, lactic acid and the like, but dicarboxylic acids such as succinic acid and adipic acid When an acid is used, there is a possibility that gels and blisters are likely to occur during molding. When hydroxycarboxylic acids such as glycolic acid and lactic acid are used, the above-mentioned problems do not occur and it is preferable from the viewpoint of excellent water solubility, and among these, lactic acid is preferable. The carboxylic acid (a) having a molecular weight of 70 or more is more preferably a carboxylic acid having a molecular weight of 75 or more, more preferably a carboxylic acid having a molecular weight of 80 or more, particularly preferably a molecular weight of 85 or more, and a molecular weight of 90 or more. Is most preferred. By using a carboxylic acid having a high molecular weight, it is possible to reduce volatile components at the time of molding, and a resin composition excellent in low odor and long run properties can be obtained.

  Content of carboxylic acid (A) in the resin composition of this invention is 0.05-5 micromol / g. When the content of carboxylic acid (A) is less than 0.05 μmol / g, coloring during melting is remarkable. On the other hand, when it exceeds 5 μmol / g, the effect of improving the low odor property and the effect of improving the adhesive force with the adhesive resin in coextrusion molding become insufficient, and the die adhesion amount tends to increase. The lower limit of the content of carboxylic acid (A) is preferably 0.1 μmol / g or more, and more preferably 0.2 μmol / g or more. The upper limit of the content of carboxylic acid (A) is preferably 4 μmol / g or less, more preferably 3 μmol / g or less, further preferably 2 μmol / g or less, and optimally 1. 5 μmol / g or less.

Further, the total content of carboxylic acid (A) and its salt in the resin composition of the present invention (μmol /
Content of carboxylic acid (a) having a molecular weight of 70 or more and its salt relative to g) (μmol / g)
The ratio is 0.1 or more. That is, the resin composition of the present invention satisfies the following formula (4).
0.1 ≦ (a ′ ) / (A ′ ) ≦ 1.0 (4)
However,
(A ′ ): Total content of carboxylic acid (A) and its salt (μmol / g)
(A ′ ): content of carboxylic acid (a) having a molecular weight of 70 or more and a salt thereof (μmol / g)

In the above formula (4), the lower limit of (a ′ ) / (A ′ ) is 0.1 or more. (A ' ) / (
When A ′ ) is less than 0.1, the effect of improving the low odor is insufficient. (A ' ) /
The lower limit of (A ′ ) is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, particularly preferably 0.95 or more, and optimally 0. .98 or more. If the ratio is less than 0.1, the effect of improving low odor and long run properties is insufficient.

  Moreover, the resin composition of this invention contains 2-25 micromol / g of alkaline-earth metal salt (B) in metal conversion. The alkaline earth metal salt (B) is not particularly limited, and examples thereof include magnesium salts, calcium salts, barium salts, beryllium salts, etc. Magnesium salts and calcium salts are particularly preferable. The anion species of the alkaline earth metal salt (B) is not particularly limited, but acetate anion, lactate anion and phosphate anion are exemplified as suitable anion species, and lactate anion is particularly preferable.

The content (M _II ) of the alkaline earth metal salt (B) is more preferably 2.5 to 20 μmol / g in terms of metal. If the content of the alkaline earth metal salt (B) is less than 2 μmol / g, the effect of improving the long run property may be unsatisfactory, and if it exceeds 25 μmol / g, the coloring at the time of melting is remarkable, and voids / holes are not formed. Occurrence is likely to occur.

  When the resin composition of the present invention is melt-molded, the intrinsic viscosity is reduced without generating voids and the like, and the lowered intrinsic viscosity is not greatly increased even during continuous operation for a long time. It is a big feature. In order to sufficiently satisfy the effects of the present invention, it is necessary to appropriately set the blending amount of the alkaline earth metal salt (B). As a result of detailed studies by the present inventors, it has been clarified that the appropriate blending amount of alkaline earth metal is closely related to the ethylene content of EVOH.

As a result of intensive studies by the present inventors, when performing melt molding, the alkaline viscosity metal salt of the resin composition is necessary so that the reduced intrinsic viscosity of the resin composition does not increase greatly even during continuous operation for a long time. It has been found that the content of (B) increases as the ethylene content of EVOH decreases. However, the increase in the content of the alkaline earth metal salt (B) makes it difficult to reduce the intrinsic viscosity without generating voids and the like. It has been clarified that this tendency becomes more prominent as the ethylene content of EVOH becomes smaller.
Table 1 shows preferable alkaline earth metal contents for achieving the effects described above in the respective ethylene contents based on the above examination.

Based on the data shown in Table 1, the EVOH ethylene content is plotted on the horizontal axis, the alkaline earth metal salt (B) content on the vertical axis, and the EVOH ethylene content and suitable alkaline earth metal salts. The relationship between the lower limit value and the upper limit value of the content of (B) was plotted (see FIG. 1).
Furthermore, from the above plot, the relationship between the ethylene content of EVOH and the lower limit (X) and upper limit (Y) of the content of the preferred alkaline earth metal salt (B) is approximated by a quadratic equation, 6) to (8) were obtained.
^{X = 0.0257 x E 2 - 2.31} x E + 54.7 (6)
^{Y = 0.0372 x E 2 - 2.43} x E + 47.7 (7)
X ≤ M _II ≤ Y (8)
However,
E: Ethylene content of ethylene-vinyl alcohol copolymer (mol%)
M _II : Content of alkaline earth metal salt (B) (metal conversion value: μmol / g)

Similarly, based on the data shown in Table 1, the ethylene content of EVOH is plotted on the horizontal axis, the alkaline earth metal salt (B) content is plotted on the vertical axis, and the ethylene content of EVOH and a more suitable alkali The relationship between the lower limit value and the upper limit value of the content of the earth metal salt (B) was plotted (see FIG. 2).
Furthermore, from the above plot, the relationship between the ethylene content of EVOH and the lower limit value (X ′) and upper limit value (Y ′) of the more preferable content of alkaline earth metal salt (B) is approximated by a quadratic equation, The following formulas (6 ′) to (8 ′) were obtained.
^{X '= 0.0286 x E 2 -} 2.55 x E + 60.1 (6')
^{Y '= 0.0229 x E 2 -} 1.46 x E + 31.2 (7')
X '≤ M _II ≤ Y' (8 ')
However,
E: Ethylene content of ethylene-vinyl alcohol copolymer (mol%)
M _II : Content of alkaline earth metal salt (B) (metal conversion value: μmol / g)

Similarly, the relationship between the ethylene content of EVOH and the lower limit value (X ″) and upper limit value (Y ″) of the more preferable content of the alkaline earth metal salt (B) is approximated by a quadratic equation, 6 ") to (8") were obtained.
^{X '' = 0.00572 x E 2} - 0.811 x E + 27.9 (6 ")
^{Y '' = 0.0229 x E 2} - 1.46 x E + 31.2 (7 ")
X '' ≤ M _II ≤ Y '' (8 ")
However,
E: Ethylene content of ethylene-vinyl alcohol copolymer (mol%)
M _II : Content of alkaline earth metal salt (B) (metal conversion value: μmol / g)

  The resin composition of the present invention preferably contains 10 to 1000 ppm of the alkali metal salt (C) in terms of metal from the viewpoint of improving adhesiveness. The lower limit of the content of the alkali metal salt (C) is preferably 30 ppm or more, and more preferably 50 ppm or more. Further, the upper limit of the content of the alkali metal salt (C) is preferably 750 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less. Although it does not specifically limit as an alkali metal salt (C), A sodium salt, potassium salt, etc. are mentioned as a suitable thing. Although the anion species of the alkali metal salt (C) is not particularly limited, acetate anion, lactate anion and phosphate anion can be exemplified as suitable anion species, and lactate anion is particularly preferable.

  If the alkali metal salt (C) is less than 10 ppm, the adhesive improvement effect may be unsatisfactory. If the alkali metal salt (C) exceeds 1000 ppm, the coloring resistance improvement effect upon melting may be insufficient. There is.

  As described above, in order to sufficiently achieve the effects of the present invention, in particular, the long run property and the self-purge property, it is important to adjust the blending amount of the alkaline earth metal salt (B). As a result of extensive studies, it has been clarified that the addition of the alkali metal salt (C) and the carboxylic acid also affects the effect of the present invention, although not as significant as the influence of the addition of the alkaline earth metal salt (B). . That is, the addition of the alkali metal salt (C) promotes the effect of the alkaline earth metal salt (B) and lowers the intrinsic viscosity [η] of the EVOH resin when heated at 220 ° C. in a nitrogen atmosphere. On the other hand, the addition of the carboxylic acid (A) suppresses the effect of the alkaline earth metal salt (B) and increases the intrinsic viscosity [η] of the EVOH resin when heat-treated at 220 ° C. in a nitrogen atmosphere. It was found to have an effect.

As a result of detailed studies by the inventors, in order to sufficiently achieve the effects of the present invention, the carboxylic acid (A), alkaline earth metal salt (B), and alkali metal salt (C) It has been found that it is particularly suitable to contain it within the range represented by the formulas (6), (7) and (9).
^{X = 0.0257 x E 2 - 2.31} x E + 54.7 (6)
^{Y = 0.0372 x E 2 - 2.43} x E + 47.7 (7)
X ≤ M _II + 0.12 x M _I -0.lx K x Ac ≤ Y (9)
However,
E: Ethylene content of ethylene-vinyl alcohol copolymer (mol%)
M _II : Content of alkaline earth metal salt (B) (metal conversion value: μmol / g)
M _I : content of alkali metal salt (C) (metal conversion value: μmol / g)
k: Acid number of carboxylic acid (A)
Ac: content of carboxylic acid (A) (μmol / g)

The above formulas (6), (7) and (9) are more preferably
^{X '= 0.0286 x E 2 -} 2.55 x E + 60.1 (6')
^{Y '= 0.0229 x E 2 -} 1.46 x E + 31.2 (7')
X '≤ M _II + 0.12 x M _I -0.1 x K x Ac ≤ Y' (9 ')
It is.

More preferably, the above formulas (6), (7) and (9) are
^{X '= 0.00286 x E 2 -} 0.543 x E + 21.0 (6 ")
^{Y '= 0.0229 x E 2 -} 1.46 x E + 31.2 (7 ")
X '≤ M _II + 0.12 x M _I -0.1 x K x Ac ≤ Y' (9 ”)
It is.

  Moreover, it is also suitable to contain 50-2000 ppm of boron compounds (D) in conversion of boron with respect to the resin composition of this invention. Examples of the boron compound (D) include, but are not limited to, boric acids, boric acid esters, borates, borohydride noodles, and the like. Specific examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid. Examples of boric acid esters include triethyl borate and trimethyl borate. Examples include alkali metal salts of acids, alkaline earth metal salts, and borax. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferable.

  When a boron compound (D) is added to a resin composition comprising EVOH, it is possible to increase the melt viscosity even when EVOH having a low degree of polymerization is used, and by using EVOH having such a low degree of polymerization, It is possible to suppress the generation of gels and blisters and to improve the long run property than EVOH. When the resin composition of the present invention contains a boron compound (D), there is a possibility that the effect of reducing the amount of die adhesion is slightly reduced during long-time melt molding for several days. It is possible to suppress the generation of gels and blisters very effectively. The lower limit of the content of the boron compound (D) is preferably 50 ppm or more in terms of boron, more preferably 100 ppm or more, and further preferably 150 ppm or more. Moreover, it is preferable that the upper limit of content of a boron compound (D) is 1500 ppm or less in conversion of boron, More preferably, it is 1000 ppm or less. When the content of the boron compound (D) is less than 50 ppm, there is a risk that the generation of gels and blisters may increase as the molding time becomes longer. There is a fear. Moreover, when content of a boron compound (D) exceeds 2000 ppm, it will be easy to gelatinize and there exists a possibility of becoming a moldability defect.

  The resin composition of the present invention contains a high-boiling carboxylic acid (a) having a molecular weight of 70 or more in an appropriate ratio, and therefore has excellent coloration resistance and appearance even during long-time melt molding. Is obtained. For this reason, it may be preferable not to add the phosphoric acid compound (E) in view of cost merit at the time of production and ease of production. However, the long run property and recoverability of the resin composition can be improved by adding the phosphoric acid compound (E). Can be further improved. In particular, it greatly contributes to the effect of improving the color resistance when performing continuous operation over a long period of several days or when accumulating heat history (for example, when recovering a molded product).

  The addition amount of the phosphoric acid compound (E) is preferably 10 to 500 ppm in terms of phosphate radical. As for content of a phosphoric acid compound (E), it is more preferable that it is 10-200 ppm in conversion of a phosphate radical, More preferably, it is 20-150 ppm. By containing the phosphoric acid compound (E) in such a range, it is possible to obtain a resin composition that gives a good appearance of a molded product with less coloring and excellent long-run properties. When content of a phosphoric acid compound (E) is less than 10 ppm, there exists a possibility that the improvement effect of the coloring resistance at the time of melt molding may become inadequate, and there exists a possibility that an external appearance property may fall. In particular, since the tendency is remarkable when the heat history is repeated, the resin composition may have poor recoverability. If it exceeds 500 ppm, the formation of gels and blisters in the molded product becomes remarkable, and the appearance deteriorates. Examples of the phosphoric acid compound (E) include, but are not limited to, various acids such as phosphoric acid and phosphorous acid and salts thereof. The phosphate may be contained in any form of primary phosphate, secondary phosphate, and tertiary phosphate, and its cationic species is not particularly limited, but as described above. Preferred alkali metal salts (C) and alkaline earth metal salts (B) are preferred. Among these, it is preferable to add the phosphoric acid compound (E) in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.

  In the resin composition of the present invention, when the heat treatment is performed at 230 ° C. in a nitrogen atmosphere, the weight reduction rate after 2 hours from the start of heating is preferably 5 to 35%. When the weight reduction rate is less than 5%, the long run property and self purge property of the resin composition may be unsatisfactory. Further, when the weight reduction rate exceeds 35%, the amount of gas generated by the decomposition becomes large, and problems such as voids may easily occur.

  In addition, the resin composition of the present invention can be blended and melt-molded with saponified ethylene-vinyl acetate copolymers having different degrees of polymerization, ethylene content and saponification, as long as the object of the present invention is not impaired. is there. 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.

  Moreover, it is also possible to mix | blend an appropriate quantity of thermoplastic resins other than this resin composition. 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, and modified polyvinyl alcohol resins.

  The obtained resin composition of the present invention is used as various molded products. A suitable example is pellets. In addition, the resin composition of the present invention is molded into various molded products such as films, sheets, containers, pipes, fibers, etc. 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. As the layer structure of the multilayer structure, E / Ad / T, T / Ad / E / Ad / T, etc., when the resin composition of the present invention is represented by E, the adhesive resin is represented by Ad, and the thermoplastic resin is represented by T. However, it is not limited to this. 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. The method of laminating using the well-known adhesive agent etc. is mentioned, Among these, the method of coextrusion with another thermoplastic resin is used preferably.

  As the thermoplastic resin laminated with the resin composition of the present invention, 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 (α-olefin having 4 to 20 carbon atoms), polybutene, polypentene and other olefins alone or copolymers thereof, polyester such as polyethylene terephthalate, polyester elastomer, nylon-6, nylon Examples thereof include polyamide resins such as −6, 6 and the like, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyurethane elastomers, polycarbonates, chlorinated polyethylene, and chlorinated polypropylene. 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 a thermoplastic resin, an adhesive resin may be used particularly when laminating by coextrusion molding. In this case, the adhesive resin is an adhesive made of a carboxylic acid-modified polyolefin. Is preferred. Here, the carboxylic acid-modified polyolefin is a modified olefin type 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 a polymer. In addition, the olefin polymer is a polyethylene (low pressure, medium pressure, high pressure), a polyolefin such as linear low density polyethylene, polypropylene, boribten, or the like, a comonomer (vinyl ester, non-polymer) capable of copolymerizing 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 0.0001 to 15% by weight, preferably 0.001 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 coextrusion method of the composition of the present invention and the thermoplastic resin is not particularly limited, and any of a multi-manifold merging method T-die method, a feed block merging method T-die method, and an inflation method may be used.

By subjecting the co-extruded multilayer structure thus obtained to secondary processing, various molded articles (films, sheets, tubes, bottles, etc.) can be obtained. Examples thereof include the following.
(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 and cup-like containers by stretch blow molding from (pipe, etc.) There are no particular limitations on such secondary processing methods, and other known secondary processing methods (blow molding, etc.) other than the above can also be employed.

  The co-extruded multilayer structure and co-injection multilayer structure obtained in this way are excellent in low odor, have little fish eye, are transparent and have few streaks. It is suitably used as a material for containers and bottles.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.

(1) Quantification of content of carboxylic acid (A) 20 g of dried pellets used as a sample was put into 100 ml of ion-exchanged water and extracted by heating at 95 ° C. for 6 hours. The extract was neutralized with 1/50 N NaOH using phenolphthalein as an indicator, and the content of carboxylic acid (A) was quantified.

(2) Quantification of the ratio of the carboxylic acid (a) having a molecular weight of 70 or more and the salt content (μmol / g) to the total content (μmol / g) of the carboxylic acid (A) and its salt 20 g was put into 100 ml of ion-exchanged water and extracted by heating at 95 ° C. for 6 hours. Using the extract, SCS5-252 manufactured by Yokogawa Electric Co., Ltd. was used for the column, and each carboxyl anion was quantified by ion chromatography using a 0.1% aqueous phosphoric acid solution as an eluent. The content of each acid and its salt was determined.

(3) Quantitative determination of Na, K, Mg, and Ca ions 10 g of dried pellets used as samples were put into 50 ml of 0.01 N hydrochloric acid aqueous solution and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography, and the amounts of Na, K, Mg, and Ca ions were quantified. The column used was ICS-C25 manufactured by Yokogawa Electric Corporation, and the eluent was an aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid. For the determination, calibration curves prepared with a sodium chloride aqueous solution, a potassium chloride aqueous solution, a magnesium chloride aqueous solution and a calcium chloride aqueous solution were used. From the amounts of Na, K, Mg, and Ca ions thus obtained, the amounts of alkaline earth metal salt (B) and alkali metal salt (C) in the dried pellets were obtained in metal equivalent amounts.

(4) Quantitative determination of boron compound (D) 100 g of dried pellets used as a sample was placed in a magnetic crucible and ashed in an electric furnace. The obtained ash was dissolved in 200 mL of 0.01 N nitric acid aqueous solution and quantified by atomic absorption analysis to obtain the content of boron compound (D) in an amount equivalent to boron.

(5) Quantification of phosphate ion 10 g of dried pellets used as a sample was put into 50 ml of 0.01N aqueous hydrochloric acid and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to determine the amount of phosphate ions. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the dissolution wave was an aqueous solution containing 2.5 mM sodium carbonate and 1.0 mM sodium bicarbonate. A calibration curve prepared with an aqueous sodium dihydrogen phosphate solution was used for the determination. From the amount of phosphate ions thus obtained, the content of the phosphate compound (E) was obtained in terms of phosphate radical.

(6) Single-layer film formation test A single-layer film was produced by the following method, and the appearance, die adhesion amount, and long run property of the molded product were evaluated.
Model Single screw extruder D20 / 20 (manufactured by Toyo Seiki)
L / D 20
Compression ratio 4
Screw diameter 20mmφ
Screw single-flight full flight type, surface nitrided steel Screw rotation speed 40rpm
Dice 300mm width straight hanger type (manufactured by Toyo Seiki)
Lip gap 0.3mm
Cylinder, die temperature setting C1 / C2 / C3 / die = 180/220/220/220 (° C)

(6-a) Void A single-layer EVOH film was formed using the sample pellet, and the occurrence of voids on the film 30 minutes after the start of film formation was visually observed. Judgment was made as follows according to the situation.
A: No occurrence B: Occurring infrequently, but no problem in practical use C: Fine voids are always seen but no problem in practical use D: Voids are generated on the entire surface E: Large holes are generated on the entire surface, and the film is reticulated

(6-b) Amount of adhesion in die After forming a single layer of EVOH using sample pellets for 8 hours, the EVOH resin in the extruder was applied for 1 hour with LDPE of MI = 1 (under 190 ° C. and 2160 g load). After substitution, the weight of the resin adhering to the inside of the die was measured, and the determination was made as follows based on the weight.
A: Less than 0.5 g B: 0.5-1 g C; 1-5 g D; 5-10 g E; 10 g or more

(6-c) Long-run property Using a sample pellet, EVOH single-layer film formation was performed, and the gel-like irregularity of the film after 8 hours (about 150 μm or more that can be confirmed with the naked eye) was counted. Converted to number. Judgment was made as follows according to the number of items.
A; Less than 20 B; 20 to 40 C; 40 to 60 D; 60 to 100 E; 100 or more

(6-d) Self-Purge Property After the EVOH monolayer film was formed for 1 hour using the sample pellet, the apparatus was turned off and the temperature was lowered to room temperature. After that, turn on the power again and rise to the set temperature, restart the operation, measure the time required for the number of gel-like lumps on the film to recover to the level before the operation suspension, and it is necessary to recover It was determined as follows according to time.
A: Recovery immediately after resumption B: Recovery within 30 minutes C: Recovery within 1 hour D: Recovery within 5 hours E: No recovery

(7) Coloring resistance A sample of 8 g of dried pellets was sandwiched between hot plates heated to 230 ° C. (Sindo tabletop test press YS-5) and heated for 10 minutes while maintaining a gap of 5 mm between the hot plates. The degree of coloring was determined with the naked eye and determined as follows.
A; colorless B; light yellow C; yellow D; dark yellow E; brown

(8) Odorousness 20 g of a resin composition sample pellet made of EVOH was placed in a 100 ml glass sample tube, the mouth was covered with aluminum foil, and then heated in a hot air dryer at 150 ° C. for 90 minutes. After removing from the dryer and allowing to cool at room temperature for 1 hour, the sample tube was shaken 2-3 times, and then the lid of the aluminum foil was removed to evaluate the odor. The intensity of the odor of the sample pellet was determined according to the following criteria.
A; no odor B; weak odor C; obvious odor D; fairly strong odor E; very strong odor

(9) Weight reduction rate About 10 mg of dried pellets used as a sample were set in a TG / DTA-220 model manufactured by Seiko Electronics, and the weight reduction rate when heated at 230 ° C for 2 hours in a nitrogen atmosphere was measured.

(10) Intrinsic viscosity 0.20 g of a sample pellet of a resin composition comprising EVOH is precisely weighed, and this is heated and dissolved in 40 ml of hydrous phenol (water / phenol = 15/85 wt%) at 60 ° C. for 3 to 4 hours. The viscosity was measured with an Ostwald viscometer at a temperature of 30 ° C. (t0 = 90 seconds), and the intrinsic (extreme) viscosity [η] was determined by the following equation.
[Η] = (2 × (ηsp−lnηrel)) ^1/2 / C (L / g)
ηsp = t / t0-1 (specific viscosity)
ηref = t / t0 (relative viscosity)
C: EVOH concentration (g / l)
T0: Time for blank (hydrous phenol) to pass through viscometer t: Time for hydrous phenol solution in which sample is dissolved to pass viscometer

Example 1
A 45% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 38 mol% was charged into a saponification reactor, and a caustic soda / methanol solution (80 g / L) was added to the vinyl ester component in the copolymer in an amount of 0. It added so that it might become 4 equivalent, and methanol was added and it adjusted so that a copolymer concentration might be 20%. The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. Four hours later, the reaction was stopped by neutralization with acetic acid, extruded from a metal plate having a circular opening into water, precipitated, and cut to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. The obtained pellets were drained with a centrifuge, and a large amount of water was further added to drain the pellets. The resulting ethylene-vinyl alcohol copolymer had a saponification degree of 99.6% and an intrinsic viscosity [η] of 0.0853 L / g.

  100 parts by weight of water-containing pellets of the ethylene-vinyl alcohol copolymer thus obtained (water content 55%) were mixed with 0.06 g / L lactic acid, 1.082 g / L magnesium lactate, 0.438 g / L sodium lactate, boric acid. It was immersed in 370 parts by weight of an aqueous solution containing 0.505 g / L and potassium dihydrogen phosphate 0.158 g / L at 25 ° C. for 6 hours. After immersion, the solution was drained and dried at 80 ° C. for 3 hours and subsequently at 107 ° C. for 24 hours using a hot air dryer to obtain dried pellets.

  The content of carboxylic acid (A) in the obtained dried pellet was 0.77 μmol / g, and the total content of carboxylic acid (A) and its salt was 18.06 μmol / g (of which carboxylic acid having a molecular weight of 70 or more) (A) and its salt content 18.06 μmol / g), the alkaline earth metal salt (B) content is 6.30 μmol / g in terms of metal, and the alkali metal salt (C) content is in terms of metal. The content of 6.33 μmol / g, boron compound (D) was 208 ppm in terms of boron, and the content of phosphoric acid compound (E) was 91 ppm in terms of phosphate radical. Further, the MFR (measured under a load of 2160 g at 190 ° C.) of the obtained EVOH resin composition pellets was 1.6 g / 10 min.

  Using the resulting dried pellets, EVOH monolayer film formation was performed, and tests for voids, die attachment amount, long run property, and self-purge property were performed. The test results for void, die attachment amount, long run property, and self-purge property were all A grades.

  When the obtained dried pellets were used for the coloration resistance and odor test by the above methods, the test results were both A.

  Using the obtained dry pellets, the weight loss rate was measured by the above method. The weight loss rate was 19%.

Examples 2-9, Comparative Examples 1-7
Table 2 summarizes the composition of the liquid in which the ethylene-vinyl alcohol copolymer having the ethylene content and intrinsic viscosity shown in Table 3 is immersed in the ethylene-vinyl alcohol copolymer after saponification, washing, and liquid removal. A dry pellet was produced in the same manner as in Example 1 except that the above was changed, and a film was produced. The evaluation results are summarized in Table 4.

[Table 3]

  Compared with Example 1, in Example 2 which does not contain a boron compound (D), long run property fell a little. Further, in Example 3 in which the content of the alkaline earth metal salt (B) was less than the lower limit of the above formula (8), the die adhesion amount and the long run property were slightly lowered. Moreover, in Example 4 using a calcium salt as the alkaline earth metal salt (B), the hue slightly decreased. Further, the content of the alkaline earth metal salt (B) is less than the lower limit of the formula (8), but the content of the carboxylic acid (A), the alkaline earth metal salt (B) and the alkali metal salt (C) is In Example 5 satisfying the above-described expression (9), the die adhesion amount and the hue slightly decreased. On the other hand, the content of the alkaline earth metal salt (B) satisfies the formula (8), but the content of the carboxylic acid (A), the alkaline earth metal salt (B) and the alkali metal salt (C) is the above-mentioned ( In Example 6 exceeding the upper limit of 9), the effect of improving voids and hue slightly decreased.

  The content of the alkaline earth metal salt (B) is less than the lower limit of the formula (8), and the content of the carboxylic acid (A), the alkaline earth metal salt (B) and the alkali metal salt (C) is (9 In Example 7, which does not satisfy the lower limit of the formula ()), all of the die adhesion amount, the long run property, and the self purge property were lowered. In Example 8 in which acetic acid, which is an acid having a molecular weight of less than 75, was added as the carboxylic acid (A), the effect of improving odor was slightly reduced. As mentioned above, although the resin composition which consists of EVOH of this invention obtained in Examples 2-8 shows a slight fall in the improvement effect of each physical property when compared with Example 1, in any of them The generation of voids was small, the appearance was excellent, the die adhesion was small, and the long run and self-purge properties were good. Moreover, also in Example 9 using EVOH having an ethylene content of 44 mol%, the excellent characteristics shown above were exhibited.

  In contrast, in Comparative Example 1 in which the content of the alkaline earth metal salt (B) is less than 2 μmol / g and in Comparative Example 3 in which the content of the carboxylic acid (A) exceeds 5 μmol / g, the die adhesion amount, long run And the self-purge property became unsatisfactory. In Comparative Example 2 in which the content of the alkaline earth metal salt (B) exceeds 25 μmol / g and in Comparative Example 4 in which the content of the carboxylic acid (A) is less than 0.05 μmol / g, generation of voids is severe. The film formation for a long time was practically impossible and the hue was inferior. Further, in Comparative Example 5 consisting only of acetic acid, which is an acid whose carboxylic acid (A) has a molecular weight of less than 75, the effect of improving odor was not obtained.

  Further, a comparative example containing almost the same amount of alkali metal salt (B) and alkali metal salt (C) as in Example 1 of JP-A-10-67898, which is the prior art, and having an ethylene content of 33 mol%. In Example 6, [η] 60 / [η] 0 exceeded 0.8, and the effect of improving the die attachment amount, the long run property, and the self purge property was not obtained.

  Further, the contents of carboxylic acid (A), alkaline earth metal salt (B), alkali metal salt (C), boron compound (D) and phosphoric acid compound (E) are substantially the same as in Example 1, but containing ethylene. In Comparative Example 7 in which the amount was 27 mol%, [η] 60 / [η] 0 exceeded 0.8, and the evaluation results for each evaluation item were unsatisfactory.

Effect of the invention

  Provided are a resin composition comprising an ethylene-vinyl alcohol copolymer with little generation of voids, excellent appearance, little die adhesion, long run property and self-purge property, and little coloration, and a multilayer structure using the same. be able to.

  It is a figure which shows the relationship between the ethylene content of EVOH, and content of a suitable alkaline-earth metal salt (B).   It is a figure which shows the relationship between ethylene content of EVOH, and content of a more suitable alkaline-earth metal salt (B).

Claims (9)

Changes in intrinsic viscosity [η] when heat-treated at 220 ° C. in a nitrogen atmosphere are the following (1) to (3
) Satisfying the formula, containing 0.05 to 5 μmol / g of carboxylic acid (A) and 6.36 to 25 μmol / g of alkaline earth metal salt (B) in terms of metal element, and satisfying the following formula (4) An ethylene-vinyl alcohol copolymer resin composition having an ethylene content of 32 to 44 mol% and a saponification degree of 80% or more.
0.05 ≦ [η] 0 ≦ 0.2 (1)
0.12 ≦ [η] 10 / [η] 0 ≦ 0.6 (2)
0.1 ≦ [η] 60 / [η] 0 ≦ 0.8 (3)
0.95 ≦ (a ′ ) / (A ′ ) ≦ 1.0 (4)
However,
[Η] 0: Intrinsic viscosity of ethylene-vinyl alcohol copolymer before heat treatment [η] 10: Intrinsic viscosity of ethylene-vinyl alcohol copolymer resin composition 10 hours after start of heat treatment [η] 60: Intrinsic viscosity (A ′ ) of ethylene-vinyl alcohol copolymer resin composition 60 hours after start of heat treatment: total content of carboxylic acid (A) and its salt (μmol / g)
(A ′ ): content of carboxylic acid (a) having a molecular weight of 70 or more and not more than the molecular weight of lauric acid and its salt (μmol / g)
The resin composition according to claim 1, wherein a change in intrinsic viscosity [η] when heat-treated at 220 ° C. in a nitrogen atmosphere satisfies the following formula (5).
0.2 ≦ [η] 60 / [η] 10 ≦ 2.5 (5)
The resin composition of Claim 1 or 2 which contains 10-1000 ppm of alkali metal salts (C) in conversion of a metal element with respect to the said resin composition.
The resin composition according to any one of claims 1 to 3, wherein a weight reduction rate after 2 hours from the start of heating in a nitrogen atmosphere at 230 ° C is 5% or more and 35% or less.
The resin composition according to any one of claims 1 to 4, wherein the carboxylic acid (a) having a molecular weight of 70 or more and a molecular weight of lauric acid or less is lactic acid.
The resin composition according to any one of claims 1 to 5, wherein the boron compound (D) is contained in an amount of 50 to 2000 ppm in terms of boron.
The resin composition according to any one of claims 1 to 6, wherein the phosphoric acid compound (E) is contained in an amount of 10 to 500 ppm in terms of phosphate radical with respect to the resin composition.
A molded article comprising the resin composition according to any one of claims 1 to 7.
A multilayer structure comprising at least one layer comprising the resin composition according to claim 1.

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