JP5813202B2 - Resin composition comprising an ethylene-vinyl alcohol copolymer excellent in low odor - Google Patents

Description

The present invention has less coloration, fish eyes (gels / butts), streaks, etc., excellent appearance, excellent long run properties during melt molding, little coloration during recovery, excellent low odor, and a laminate. In some cases, the present invention relates to a resin composition comprising an ethylene-vinyl alcohol copolymer excellent in interlayer adhesion and a multilayer structure using the same.
About.

  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 a packaging material is usually manufactured by melt molding, and has a long run property at the time of melt molding (a molded product free of fish eyes and streaks can be obtained even when molding for a long time), appearance of the molded product (less coloring) , A molded product in which the generation of fish eyes is not observed) is required. In recent years, recyclability has also become an important issue. Even when an EVOH molded product is recovered, melt molded again, and heat history is repeated, the recoverability (moldability of recovered EVOH) is good. There is a need for EVOH that is less colored during recovery. Furthermore, in general, in order to impart mechanical strength, moisture resistance, heat sealability, etc., a laminate is coextruded through a base material such as a polyolefin-based resin and an adhesive layer. Body interlayer adhesion is also important. That is, it is necessary to sufficiently satisfy the appearance of the molded product, the long run property during melt molding, the recoverability, and the interlayer adhesion of the laminate.

Therefore, conventionally, as such countermeasures, the following proposals have been made for producing an excellent molded article by treating an ethylene-vinyl alcohol copolymer with various acids and metal salts.
For example, (1) In order to improve the appearance represented by the above long-run property and gel / buts, the metal salt of Group II of the Periodic Table is added in an amount of 0.0005 to 0.05% by weight (in terms of metal element), pKa3 0.002 to 0.2% by weight of an acid having a boiling point of 180 ° C. or higher and a boiling point of 120 to 120 ° C. An EVOH composition exhibiting flow characteristics is disclosed (Japanese Patent Laid-Open No. 64-66262). (2) An EVOH composition containing hydroxycarboxylic acid and / or a salt thereof, an alkali metal salt, an alkaline earth metal salt, a phosphate, or a boron compound is disclosed in order to improve coloring, appearance, and interlayer adhesion. (JP-A-10-67898). Further, in this publication, as Example 1, with respect to 100 parts by weight of EVOH, lactic acid 2000 ppm (as lactic acid root), alkali metal salt 350 ppm (in metal element conversion), alkaline earth metal 50 ppm (in metal element conversion), phosphorus compound 30 ppm ( A resin composition containing 40 ppm (in terms of boron element) and a boron compound (in terms of phosphorus) is disclosed.

JP-A 64-66262 Japanese Patent Laid-Open No. 10-67898

  However, in the techniques disclosed in the above (1) and (2), those that simultaneously satisfy the appearance of the molded product, the long run property during melt molding, the interlayer adhesion of the laminate, the recyclability, and the low odor property. It is not found, and at the present time, there is a demand for improvement of moldings with advanced functions and quality and the working environment when manufacturing them, so it has not reached a satisfactory level. is the current situation.

  In addition, EVOH having excellent low odor properties is required in order to improve the working environment at the time of production of the resin composition and at the time of melt molding, but the above prior art has no description about odor.

  The problems described above are solved by the resin composition of the present invention. That is, it is a resin composition comprising an ethylene-vinyl alcohol copolymer, and when heated at 220 ° C. in a nitrogen atmosphere, the MFR (230 ° C., 10.9 kg load) of the resin composition is minimal after the start of heating. After showing the minimum value, the maximum value (MFRmax) is shown, 0.05 to 4 μm / g of carboxylic acid (A) is contained, and the lubricant is 0 with respect to 100 parts by weight of the ethylene-vinyl alcohol copolymer. It is solved by providing a resin composition characterized by containing 0.005 to 1 part by weight.

  In a preferred embodiment, the resin composition of the present invention contains 50 to 500 ppm of an alkali metal salt (B) in terms of a metal element.

  In a preferred embodiment, the resin composition of the present invention comprises an alkaline earth metal salt (C) in an amount of 10 to 120 ppm in terms of metal element.

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

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

In a preferred embodiment, the resin composition of the present invention satisfies the following formula (3).
[B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] = 2-9 (3)
However,
A: Content of carboxylic acid (A) per unit weight of the resin composition (μmol / g)
B: Content of alkali metal salt (B) per unit weight of the resin composition (μmol / g)
C: Content of alkaline earth metal salt (C) per unit weight of the resin composition (μmol / g)
D: content of phosphoric acid compound (D) per unit weight of the resin composition (μmol / g)

  The resin composition of the present invention contains 0.005 to 1 part by weight of a lubricant with respect to 100 parts by weight of EVOH.

  In a preferred embodiment, the pellet made of the resin composition of the present invention is formed by adhering 0.005 to 0.5 part by weight of a lubricant to the outer surface of the pellet with respect to 100 parts by weight of the resin composition.

  The present invention also relates to a multilayer structure obtained by laminating a thermoplastic resin on at least one side of the layer made of the resin composition.

  Less coloration, fish eyes (gels and blisters), streaks, etc., excellent appearance, excellent long run at melt molding, little color at recovery, excellent low odor, and interlayer adhesion when laminated The resin composition which consists of an ethylene-vinyl alcohol copolymer excellent in the property, and a multilayer structure using the same can be provided.

It is a figure which shows the relationship between the heating time in 220 degreeC of the resin composition which consists of EVOH, and MFR (230 degreeC, 10.9 kg load).

  As EVOH used for this invention, what is obtained by saponifying an ethylene-vinyl acetate copolymer is preferable, Among these, ethylene content is 3-70 mol% suitably. From the viewpoint of obtaining a molded article excellent in gas barrier properties and melt moldability, the ethylene content is preferably 10 to 65 mol%, more preferably 20 to 65 mol%, and most preferably 25 to 60 mol%. Some are preferred. Furthermore, the saponification degree of the vinyl acetate 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.

  On the other hand, EVOH having an ethylene content of 3 to 20 mol% is suitably used as EVOH imparted with water solubility, and such an EVOH aqueous solution is excellent in barrier properties and coating film stability and is used as an excellent coating material.

  Further, when ethylene and vinyl acetate are copolymerized, other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.) can 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 acetate 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 acetate, and ethylene-vinyl acetate 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%.
Ethylene content in the copolymer; preferably 3 to 70 mol%, more preferably 25 to 60 mol%.

  In addition to ethylene and vinyl acetate, 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 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, 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 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.

When the resin composition of the present invention is heated at 220 ° C. in a nitrogen atmosphere, the MFR (230 ° C., 10.9 kg load) of the resin composition shows a minimum value within 10 hours from the start of heating, and the minimum value It is extremely important that the maximum value (MFRmax) is exhibited within 100 hours from the point of view and that the following formula (1) is satisfied. In addition, a resin composition comprising EVOH excellent in long run properties, appearance of molded products, recoverability, coloration resistance during recovery, and interlayer adhesion can be obtained.
0.5 ≦ MFRmax / MFR0 ≦ 45 (1)
However,
MFRmax: Maximum value of MFR (230 ° C., 10.9 kg load) of the resin composition when the resin composition is heated at 220 ° C. in a nitrogen atmosphere MFR0: MFR of the resin composition not subjected to heat treatment (230 ° C, 10.9kg load)
The resin composition comprising EVOH of the present invention showing such melting behavior has a small amount of resin die attached during melt molding. Further, even during extremely long melt molding, it is possible to suppress gels and blisters of a molded product (film, etc.). That is, the resin composition comprising EVOH of the present invention is extremely excellent in long run properties.

  On the other hand, when the resin composition composed of EVOH does not have the above-described configuration (Comparative Example 4: see FIG. 1), not only the effect of reducing the die adhesion amount is obtained, but also a long-term continuous operation was performed. In some cases, it is clear that the number of generated gels and blisters increases.

Further, as a result of detailed studies by the present inventors, it has been clarified that the resin composition comprising EVOH not having the above-described structure may rapidly increase the occurrence frequency of gels and blisters during long-term operation. . This sudden increase in the frequency of gel and buoyancy is not permanent, and usually after several minutes to several tens of minutes have passed since the frequency of the occurrence of gel and rashes, the normal level of gel and butsu Returning to the occurrence frequency, the appearance of the molded product when the occurrence frequency of gels and blisters rapidly increases is poor in appearance, and usually a product that can withstand practical use cannot be obtained.
However, by using the resin composition of the present invention developed by the present inventors, it has become possible to effectively suppress a sudden increase in the occurrence frequency of gels and blisters even during long melt molding. As described above, by using the resin composition of the present invention, long-time molding can be performed without problems even in applications that require an extremely high appearance such as a film, and productivity can be improved. From this viewpoint, the significance of the present invention is great.

The resin composition comprising EVOH of the present invention satisfies the following formula (1).
0.5 ≦ MFRmax / MFR0 ≦ 45 (1)
However,
MFRmax: Maximum value of MFR (230 ° C., 10.9 kg load) of the resin composition when the resin composition is heated at 220 ° C. in a nitrogen atmosphere MFR0: MFR of the resin composition not subjected to heat treatment (230 ° C, 10.9kg load)
The lower limit of MFRmax / MFR0 is more preferably 0.7, and even more preferably 1. The upper limit of MFRmax / MFR0 is more preferably 35, more preferably 25, still more preferably 20, and optimally 10. When the value of MFRmax / MFR0 is within such a range, the amount of the heat-degraded resin adhering to the molding machine die and the occurrence of gels and blisters of the molded product during the melt molding of the resin composition are small, and the gels and blisters are generated. It is possible to obtain a resin composition composed of EVOH with excellent frequency resistance, in which frequency fluctuations are suppressed.

  If the value of MFRmax / MFR0 is less than 0.5, the amount of resin adhesion to the molding machine die increases and the long run property deteriorates, and the effect of suppressing fluctuations in the occurrence frequency of gels and blisters is insufficient. Become. Further, it is clear from Comparative Example 5 that when the value of MFRmax / MFR0 exceeds 45, coloring due to the decomposition of EVOH becomes remarkable and the appearance becomes poor.

  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 resin composition of the present invention contains 0.05 to 4 μmol / g of carboxylic acid (A) and satisfies the following formula (2).
0.1 ≦ (a1) / (A) ≦ 1.0 (2)
However,
(A): Total content of carboxylic acid (A) and its salt (μmol / g)
(A1): content of carboxylic acid (a1) having a molecular weight of 75 or more and a salt thereof (μmol / g)

  Examples of the carboxylic acid (a1) having a molecular weight of 75 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. 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.

  In particular, when lactic acid is used as the carboxylic acid (a1) having a molecular weight of 75 or more, it is preferable in that it is excellent in water solubility as described above and has extremely low volatility compared with acetic acid. When producing pellets comprising an EVOH resin composition, it is usually necessary to dry the pellets in a water-containing state, but even in such a drying step, volatilization of the acid component is greatly suppressed and more stable by using lactic acid. Can produce quality products. In addition, since lactic acid (pKa at 25 ° C. = 3.858) is stronger than acetic acid (pKa at 25 ° C. = 4.756), the amount of acid used can be reduced. Lactic acid has low volatility and requires a small amount of use, so that the outflow of the acid component to the outside of the system in the production process of the EVOH resin composition can be significantly reduced, reducing the burden on the operator. be able to. Furthermore, the load on the environment around the production facility (factory, etc.) can be greatly reduced.

  As the carboxylic acid (a1) having a molecular weight of 75 or more, a carboxylic acid having a molecular weight of 80 or more is more preferable, a molecular weight of 85 or more is more preferable, and a molecular weight of 90 or more is particularly preferable. 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 0.05-4 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 4 μmol / g, the effect of improving the low odor property and the effect of improving the adhesive strength 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. Further, the upper limit of the content of the carboxylic acid (A) is preferably 3 μmol / g or less, more preferably 2.5 μmol / g or less, and further preferably 2 μmol / g or less. It is 1.5 μmol / g or less.

Moreover, as above-mentioned, the resin composition of this invention satisfies following formula (2).
0.1 ≦ (a1) / (A) ≦ 1.0 (2)
However,
(A): Total content of carboxylic acid (A) and its salt (μmol / g)
(A1): content of carboxylic acid (a1) having a molecular weight of 75 or more and a salt thereof (μmol / g)

  The ratio of the carboxylic acid (a1) having a molecular weight of 75 or more and the salt content (μmol / g) to the total content (μmol / g) of the carboxylic acid (A) and the salt thereof in the resin composition of the present invention, The lower limit of (a1) / (A) in the above formula (2) is 0.1 or more. If the ratio is less than 0.1, the effect of improving low odor and long run properties is insufficient. The lower limit of (a1) / (A) in the above formula (2) is preferably 0.5 or more, more preferably 0.7 or more, particularly preferably 0.9 or more, and optimally 0.8. 98 or more.

  In the resin composition of the present invention, the alkali metal salt (B) is preferably contained in an amount of 50 to 500 ppm in terms of a metal element from the viewpoint of improving adhesiveness, and more preferably 100 to 300 ppm. Although alkali metal salt (B) is not specifically limited, Sodium salt, potassium salt, etc. are mentioned as a suitable thing. The anion species of the alkali 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.

  If the alkali metal salt (B) is less than 50 ppm, the adhesion improving effect may be unsatisfactory. If the alkali metal salt (B) exceeds 500 ppm, the coloring resistance improving effect upon melting may be insufficient. There is.

  The resin composition of the present invention preferably contains 10 to 120 ppm of alkaline earth metal salt (C) in terms of metal element, and more preferably contains 20 to 100 ppm. By containing the alkaline earth metal salt in such a range, the MFR over time of the resin composition made of EVOH can be easily controlled, and the inside of the molding machine die of the thermally deteriorated resin at the time of melt molding using the resin composition It is possible not only to reduce the amount of adhesion to but also to improve long run performance. If the content of the alkaline earth metal salt is less than 10 ppm, the effect of improving the long run property may be unsatisfactory, and if it exceeds 120 ppm, the coloring at the time of melting is remarkable.

  The alkaline earth metal salt (C) is not particularly limited, and examples thereof include magnesium salts, calcium salts, barium salts, beryllium salts, and the like, and magnesium salts and calcium salts are particularly preferable. The anion species of the alkaline earth metal salt (C) is not particularly limited, but acetate anion, lactate anion and phosphate anion are exemplified as suitable anion species, and lactate anion is particularly preferable.

  When the alkaline earth metal salt (C) in the resin composition of the present invention is a magnesium salt, the preferred content is 10 to 60 ppm, more preferably 20 to 50 ppm in terms of metal element. Moreover, suitable content in case the alkaline-earth metal salt (C) in a resin composition is a calcium salt is 20-120 ppm in conversion of a metal element, More preferably, it is 40-100 ppm.

  Since the resin composition of the present invention contains a high-boiling carboxylic acid (a1) having a molecular weight of 75 or more in an appropriate ratio, it is a molded product excellent in coloration resistance and appearance even during long melt molding. Is obtained. For this reason, it may be preferable not to add the phosphoric acid compound (D) from the cost merit at the time of production and the simplicity of production, but the long run property and recoverability of the resin composition by adding the phosphoric acid compound (D). 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 (D) is preferably 10 to 500 ppm in terms of phosphate radical. As for content of a phosphoric acid compound (D), it is more preferable that it is 10-200 ppm in conversion of a phosphate group, More preferably, it is 20-150 ppm. By containing the phosphoric acid compound 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 (D) 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 (D) 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 are alkali metal salts and alkaline earth metal salts. Among these, it is preferable to add the phosphoric acid compound (D) in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.

  Moreover, it is also suitable to contain 50-2000 ppm of boron compounds (E) in conversion of a boron element with respect to the resin composition of this invention. Examples of the boron compound (E) include, but are not limited to, boric acids, boric acid esters, borates, borohydrides, 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 is added to a resin composition comprising EVOH, it is possible to increase the melt viscosity even when EVOH having a low polymerization degree is used. In addition, it is possible to suppress the generation of gels and blisters and improve the long run property. When the resin composition of the present invention contains a boron compound (E), there is a possibility that the effect of reducing the amount of die adhesion is slightly reduced during long-time melt molding such as 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 (E) is preferably 50 ppm or more in terms of boron element, 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 (E) is 1500 ppm or less in conversion of a boron element, More preferably, it is 1000 ppm or less. When the content of the boron compound (E) 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 (E) exceeds 2000 ppm, it will be easy to gelatinize and there exists a possibility that it may become a moldability defect.

Moreover, in this invention, when the resin composition of this invention satisfies following formula (3), it becomes possible to obtain the effect of this invention more notably, and it is preferable.
[B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] = 2-9 (3)
However,
A: Content of carboxylic acid (A) per unit weight of the resin composition (μmol / g)
B: Content of alkali metal salt (B) per unit weight of the resin composition (μmol / g)
C: Content of alkaline earth metal salt (C) per unit weight of the resin composition (μmol / g)
D: content of phosphoric acid compound (D) per unit weight of the resin composition (μmol / g)

  By increasing the content of alkali metal salt (B) and alkaline earth metal (C) in the resin composition comprising EVOH, the adhesiveness of the resin composition and the effect of reducing the amount of die adhesion are improved, and MFRmax / MFR0 generally increases. However, addition of an excessive amount of alkali metal salt (B) and alkaline earth metal salt (C) not only deteriorates the color resistance but also adversely affects low odor due to decomposition of the resin composition.

  On the other hand, by increasing the content of the carboxylic acid (A) and the phosphoric acid compound (D) in the resin composition comprising EVOH, the coloring resistance of the molded product can be improved, and MFRmax / MFR0 generally decreases. To do. It is also possible to improve long run properties by adding appropriate amounts of carboxylic acid (A) and phosphoric acid compound (D). However, addition of an excessive amount of the carboxylic acid (A) and the phosphoric acid compound (D) leads to an increase in gels and blisters, and further decreases the adhesiveness of the resin composition. As described above, the effects of the carboxylic acid (A), the alkali metal salt (B), the alkaline earth metal salt (C), and the phosphoric acid compound (D) on the properties of the resin composition are mutually related. A resin composition composed of EVOH that exhibits high performance in all aspects of low odor, long run during melt molding, appearance, recoverability, coloring resistance and interlayer adhesion by blending these in a balanced manner. It is possible to obtain things.

  Here, when the resin composition of the present invention satisfies the above-mentioned formula (3), it is possible to obtain a resin composition that is highly balanced particularly in the interlayer adhesion strength and the appearance of the molded product. When [B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] is less than 2, there is a concern that the interlayer adhesive strength may be lowered. There is a possibility that coloring will be remarkable and appearance of the molded product will be deteriorated. The lower limit of [B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] is more preferably 3 or more, and even more preferably 4 or more. The upper limit is more preferably 8 or less, and even more preferably 7 or less.

  Moreover, it is also suitable to add 0.005-1 weight part of lubricant with respect to 100 weight part of EVOH to the EVOH resin composition of this invention. By adding a lubricant, it is possible not only to reduce the amount of attached die, but also to obtain a resin composition made of EVOH which is difficult to be colored at the time of recovery and has good long run properties. The effect of such a lubricant is particularly remarkable when the resin composition of the present invention contains a boron compound (E). Further, when the resin composition of the present invention contains a boron compound (E), the effect of suppressing fluctuations in the occurrence frequency of gels and blisters is slightly reduced when continuously performing melt molding for an extremely long time. Sometimes. However, as a result of detailed investigations by the present inventors, surprisingly, by adding 0.005 to 1 part by weight of a lubricant to 100 parts by weight of EVOH of the resin composition comprising such EVOH, a gel is obtained. -It has been found that the effect of suppressing fluctuations in the frequency of occurrence of irregularities can be maintained over an extremely long period of time.

  The preferred lubricant content is 0.005 to 1 part by weight of lubricant with respect to 100 parts by weight of EVOH. When the lubricant content is less than 0.005 parts by weight with respect to 100 parts by weight of EVOH, the effect of adding the lubricant as described above may be insufficient, and when it exceeds 1 part by weight, surging may easily occur. There is a possibility that the extrusion stability deteriorates. The lower limit of the content of the lubricant is more preferably 0.01 parts by weight or more with respect to 100 parts by weight of EVOH. Further, the upper limit of the content of the lubricant is more preferably 0.8 parts by weight or less, more preferably 0.7 parts by weight or less, and most preferably 0.5 parts by weight or less with respect to 100 parts by weight of EVOH. It is.

  The lubricant that can be used in the present invention is not particularly limited, and examples thereof include higher fatty acid amides, higher fatty acid metal salts (for example, calcium stearate), low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene). However, it is not limited to this. Among these, higher fatty acid amides are preferably used. Specifically, higher saturated fatty acid amides (for example, stearic acid amide, palmitic acid amide, lauric acid amide, etc.), higher unsaturated fatty acid amides (for example, oleic acid amide, erucic acid) Amides), higher bis fatty acid amides (for example, ethylene bis stearamide, methylene bis stearamide, etc.) and the like. Here, the higher fatty acid means a fatty acid having 6 or more carbon atoms, and more preferably 10 or more carbon atoms.

  The form of the lubricant may be any of powder, solution, and dispersion liquid, and is not particularly limited. Also, the form of the lubricant is not particularly limited, and a method of melt-mixing the resin composition and the lubricant, a method of extruding the solution after the saponification reaction to which the lubricant has been added, into a coagulating liquid, and a method of combining these Etc.

  In addition, a resin composition pellet obtained by adhering 0.005 to 0.5 part by weight of a lubricant with respect to 100 parts by weight of the resin composition on the outer surface of the pellet made of the resin composition of the present invention is also an embodiment of the present invention. It is suitable as. The lower limit of the amount of lubricant adhered to the pellet is more preferably 0.01 parts by weight or more with respect to 100 parts by weight of EVOH. The upper limit of the amount of lubricant adhered to the pellet is more preferably 0.3 parts by weight or less, more preferably 0.2 parts by weight or less, and most preferably 0.1 parts by weight or less with respect to 100 parts by weight of EVOH. Less than parts by weight. When the amount of the lubricant adhering to the outer surface of the pellet made of the resin composition exceeds 0.5 parts by weight with respect to 100 parts by weight of the resin composition, the pellet feed to the extruder may be difficult to stabilize. is there. Although the manufacturing method of this resin composition pellet is not specifically limited, The method of dry-blending EVOH resin composition pellet and a lubricant is illustrated as a suitable thing.

  Suitable melt flow rate (MFR) of the resin composition comprising EVOH obtained in the present invention (measured at 190 ° C. under a load of 2160 g; provided that the melting point is around 190 ° C. or exceeds 190 ° C. under a load of 2160 g, the melting point It is measured at the above plural temperatures, and in a semi-logarithmic graph, the reciprocal absolute temperature is plotted on the horizontal axis, the melt flow rate is plotted on the vertical axis (logarithm), and the value extrapolated to 190 ° C.) is preferably 0.1 200 g / 10 min. It is. The lower limit of MFR is more preferably 0.2 g / 10 min. More preferably, 0.5 g / 10 min. Above, optimally 1 g / 10 min. That's it. Further, the upper limit of MFR is more preferably 50 g / 10 min. Or more preferably 10 g / 10 min. And optimally 7 g / 10 min. It is as follows. When the melt flow rate is smaller than the above range, the inside of the extruder is in a high torque state at the time of molding, making extrusion difficult, and when larger than the range, the mechanical strength of the molded product is insufficient, which is preferable. Absent.

  In addition, EVOH having a different degree of polymerization, ethylene content, and saponification degree can be blended and melt-molded in the resin composition of the present invention 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.

  There is no particular limitation on the method of adding EVOH to carboxylic acid (A) and, if necessary, alkali metal salt (B), alkaline earth metal salt (C), phosphoric acid compound (D) and boron compound (E). For example, there are 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. .

  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 the EVOH is immersed in a solution containing the carboxylic acid (A) and, if necessary, an alkali metal salt (B), an alkaline earth metal salt (C), a phosphoric acid compound (D) and a boron compound (E), the above The concentrations of the carboxylic acid (A) in the solution, and the alkali metal salt (B), alkaline earth metal salt (C), phosphoric acid compound (D) and boron compound (E) added as necessary are as follows: There is no particular limitation. The solvent of the solution is not particularly limited, but is preferably an aqueous solution for reasons of handling. 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. Among these, all of carboxylic acid (A), alkali metal salt (B), alkaline earth metal salt (C), phosphoric acid compound (D) and boron compound (E) added as necessary are included. Treatment with a solution is preferable from the viewpoint of simplification of the process. When the treatment is performed by immersing in the solution as described above, the final EVOH composition is obtained by drying.

  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. 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 of melt-extruding a thermoplastic resin into a molded article (film, sheet, etc.) comprising the resin composition of the present invention, a method of co-extruding the resin composition of the present invention and another thermoplastic resin, a thermoplastic resin And a resin composition comprising EVOH and a molded product obtained from the EVOH resin composition of the present invention and a film and sheet of another substrate are combined with an organic titanium compound, an isocyanate compound, and a polyester system. Examples include a method of laminating using a known adhesive such as a compound, and among them, a method of co-extrusion with other thermoplastic resins is preferably used.

  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 ester 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 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. 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. is there. These adhesive resins may be used alone or as a mixture of two or more layers.

  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 multilayer structure thus obtained is excellent in low odor, has few fish eyes, is transparent and has few streaks, and is therefore suitable as a material for food containers such as deep-drawn containers, cup-shaped containers, bottles, etc. Used for.

  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) Determination of the ratio of the carboxylic acid (a1) having a molecular weight of 75 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) Determination of alkali metal salt (B) and alkaline earth metal salt (C) (quantification of Na ion, K ion, Mg ion, and Ca ion)
10 g of dried pellets as a sample 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 ions, K ions, Mg ions, 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 ions, K ions, Mg ions, and Ca ions thus obtained, the amounts of alkali metal salt (B) and alkaline earth metal salt (C) in the dried pellets were obtained in terms of metal elements. .

(4) Quantification of phosphate compound (D) (quantification of phosphate ion)
10 g of dried pellets as a sample 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 to determine the amount of phosphate ions. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the eluent 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 (D) was obtained in terms of phosphate radical.

(5) Quantification of boron compound (E) 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 (E) in an amount equivalent to boron element.

(6) Relationship between heating time and MFR 3-4 g of dried pellets as a sample are placed in a stainless steel pipe (inner diameter: 2.2 cm, length: 12.5 cm, inner volume: 50 cm ³ ) under a nitrogen atmosphere. Was sufficiently replaced with nitrogen gas, followed by heat treatment at 220 ° C. After heat treatment, the resin MFR was changed to a melt indexer {Treasure Industry Co., Ltd. melt indexer L203 (cylinder hole diameter φ9.48 mm, piston diameter φ9.48 mm, die diameter φ2.09 mm, die length 8.01 mm) )}, The resin was heated at 230 ° C. for 6 minutes, then loaded with 10.9 kg and measured.

(7) Heat Melt Coloring Test 8 g of dried pellets as a sample were 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: No coloring B: Slightly yellow C: Yellowing D: Intense coloring

(8) Single-layer film formation test A single-layer film was prepared by the following method, and the appearance, die adhesion amount, and long run property of the molded product were evaluated.
Type Single-screw extruder (non-vent type)
L / D 20
Diameter 20mmφ
Screw single-flight full flight type, surface nitrided steel Screw rotation speed 40rpm
Die 300mm width coat hanger die
Lip gap 0.3mm
Cylinder, die temperature setting C1 / C2 / C3 / die = 195/230/230/220 (° C)

(8-a) Variation in the number of occurrences of gelled blisters and the frequency of occurrence of gelled blisters The above-mentioned film formation was continued for 8 days, and the film was sampled every hour to obtain gelled blisters (about 150 μm that can be confirmed with the naked eye). The above were counted and converted per 1.0 m ² , and the average value per day of the number of gelled beads was obtained from the obtained data. In addition, during the film-forming test, the state of streaks and gel-like irregularities is continuously observed visually, and the number of streaks and gel-like irregularities increases rapidly (100 / m ² or more) per day. did.
(8-b) Die adhesion amount After carrying out EVOH monolayer film formation for 8 hours using the sample resin composition, the EVOH resin in the extruder was replaced with LDPE (low density polyethylene) with MFR = 1 over 1 hour. Thereafter, the weight of the EVOH thermally deteriorated resin adhering to the inside of the die was measured. The weight was determined as follows.
A; less than 1.5 g B; 1.5 to 5 g C; 5 to 10 g D; 10 g or more

(9) Interlaminar adhesive strength T-type peel strength between an ethylene-vinyl alcohol copolymer / adhesive resin immediately after film formation of a three-kind five-layer film obtained by the following coextrusion molding is 20 ° C.-65% RH condition Below, it measured using the autograph (tensile speed of 250 mm / min). The determination was made as follows according to the peel strength value.
A: 500 g / 15 mm or more B; 300 to less than 500 g / 15 mm C; less than 300 g / 15 mm (coextrusion molding conditions)
Layer structure: LLDPE / adhesive resin / EVOH resin composition / adhesive resin / LLDPE (thickness 50/10/10/10/50: unit is μm)
LLDPE: Mitsui Chemicals' Ultra Zex 3523L
Adhesive resin: Bondin TX8030 manufactured by Sumitomo Chemical
Extrusion temperature of each resin: C1 / C2 / C3 / die = 170/170/220/220 ° C.
Extruder for each resin, T-die specifications:
LLDPE: 32φ Extruder GT-32-A (Plastic Engineering Laboratory)
Adhesive resin; 25φ extruder P25-18AC (Osaka Seiki)
EVOH; 20φ Extruder Lab Machine ME Type CO-EXT (Toyo Seiki)
T-die: 300mm width, 3 types, 5 layers (Plastic Engineering Laboratory)
Cooling roll temperature: 50 ° C
Pickup speed: 4m / min

(10) Recoverability The formed EVOH monolayer film (film-formed product up to 2 hours after the start of film formation) is pulverized, melted and pelletized again (the pelletization temperature is 220 ° C.), and the pellet is used. Then, single-layer film formation was performed again.
(10-a) Coloring resistance The film was wound around a paper tube, and the degree of coloration of the film end face was determined with the naked eye and determined as follows.
A: No coloring B: Slightly yellowing C: Yellowing D: Severe coloring (10-b) generation of gel 1 hour after the formation of a single layer film (thickness of about 150 μm or more that can be confirmed with the naked eye) ) Was counted and converted per 1.0 m ² . 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 or more

(11) 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; Clear odor D: Very strong odor

(12) Intrinsic viscosity A 0.20 g sample pellet of a resin composition composed of 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 / t ₀ −1 (specific viscosity)
ηrel = t / t ₀ (relative viscosity)
C: EVOH concentration (g / l)
· T _0: time a blank (hydrous phenol) passes the viscometer · t: time hydrous phenol solution obtained by dissolving the sample passes through the 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 acetate 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.

  100 parts by weight of the thus obtained water-containing pellets of ethylene-vinyl alcohol copolymer (ethylene content 38 mol%, saponification degree 99.4%, water content 55% by weight), sodium lactate 0.8 g / L, lactic acid It was immersed in 370 parts by weight of an aqueous solution containing 0.31 g / L of magnesium, 0.17 g / L of potassium dihydrogen phosphate, 0.08 g / L of lactic acid, and 0.32 g / L of boric acid 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. To 100 parts by weight of the dried pellets, 0.02 part by weight of lubricant Alflow H-50T (manufactured by NOF Corporation; ethylene bisstearic acid amide) was dry blended and mixed thoroughly to obtain EVOH resin composition pellets.

  The content of carboxylic acid (A) in the obtained dried pellet is 0.90 μmol / g, and the total content of carboxylic acid (A) and its salt is 10.3 μmol / g (of which carboxylic acid having a molecular weight of 75 or more) (A1) and its salt content 10.3 μmol / g) The content of alkali metal salt (B) is 220 ppm in terms of metal element, the content of alkaline earth metal salt (C) is 35 ppm in terms of metal element, phosphorus The content of the acid compound (D) was 100 ppm in terms of phosphate radical, and the content of the boron compound (E) was 240 ppm in terms of boron element. The obtained EVOH resin composition pellets had an MFR (measured at 190 ° C. under a load of 2160 g) of 2.0 g / 10 min and an intrinsic viscosity of 0.085 l / g.

  Using the obtained EVOH resin composition pellets, the relationship between the heating time and MFR was examined according to the above-described method (see FIG. 1), and a heating melt coloring test was conducted. MFRmax / MFR0 was 1.8, and the result of the heat-melt coloring test was A. Moreover, said resin composition showed the minimum value (MFRmax) within 100 hours after MFR showed the minimum value within 10 hours from the start of heating.

Using the obtained EVOH resin composition pellets, a single-layer film-forming test was performed according to the above-described method, and the number of generated gelled particles, the variation in the frequency of generated gelled particles, and the amount of attached die were examined. The occurrence of gelled spots is as small as 6-7 pieces / m ^{2 on} average over 8 days, and there is no temporary steep increase of streaks or gelled spots, and a molded article with a good appearance can be obtained. Long run characteristics were shown. The test result of the die adhesion amount was also A.

  Using the obtained EVOH resin composition pellets, interlayer adhesion was measured by the method described above. The T-type peel strength between the resin composition / adhesive resin composed of EVOH immediately after film formation was A.

  Using the film obtained by the single-layer film formation test (film-formation product up to 2 hours after the start of film formation), the test for recoverability ((a) coloration resistance and (b) generation of blisters) is performed by the above method. went. As a result of the test, the recoverability was determined as A in any of the evaluation items of (a) anti-coloring property and (b) occurrence of bumps.

  Using the obtained EVOH resin composition pellets, an odor test was conducted by the method described above. The odor was A.

Examples 2 to 5, A, Comparative Examples 1, 2, 4, 5, A
Table 1 shows the composition of a liquid in which EVOH having the intrinsic viscosity shown in Table 2 is used to immerse pellets made of EVOH having an ethylene content of 38 mol% and a saponification degree of 99.4% after saponification, washing, and devolatilization. A dry pellet was prepared in the same manner as in Example 1 except that the change was made as shown in FIG. Table 2 summarizes the composition of the pellets used in each example and comparative example, and Table 3 summarizes the evaluation results of various tests.

  The resin compositions of Examples 2 to 5, A, Comparative Examples 1, 2, 5 and A had a minimum value within 10 hours from the start of heating, and the maximum value (within 100 hours after the minimum value was reached). MFRmax). However, in the resin composition of Comparative Example 4, MFR showed neither a minimum value nor a maximum value.

  The resin compositions composed of EVOH of Examples 1 to 6 having the structure of the present invention are excellent in appearance with little coloration, fish eyes (gels and blisters), streaks, etc., and excellent in long run properties during melt molding. In addition, there was little coloring at the time of collection, and the interlayer adhesion was excellent when a laminate was obtained. In Comparative Example A, which does not contain a lubricant, when compared with Example 1, the coloration resistance at the time of recovery, the effect of improving the generation of gels and blisters, and the effect of reducing the amount of attached die are slightly reduced. Although the inhibitory effect and the effect of suppressing the frequency of sudden increase in the number of gelled spots were somewhat reduced, they could be put to practical use.

  However, in Comparative Example 1 in which the content of the carboxylic acid (A) in the resin composition exceeds 4 μmol / g, sufficient adhesion cannot be obtained, and conversely, the content of the carboxylic acid (A) is 0.05 μmol / g. In Comparative Example 2, which is less than 1, the coloring resistance was unsatisfactory, and the effect of suppressing the occurrence of gels and blisters was not sufficiently obtained.

  Also, acetic acid is used as the carboxylic acid (A), and the carboxylic acid (a1) having a molecular weight of 75 or more and the salt content (μmol / g) relative to the total content (μmol / g) of the carboxylic acid (A) and its salt. In Example A in which the ratio of 0 was 0, the effect of improving odor was unsatisfactory.

  In addition, regarding the relationship between the heating time at 220 ° C. in a nitrogen atmosphere of the resin composition and MFR (230 ° C., 10.9 kg load), MFR showed a minimum value within 10 hours from the start of heating and showed a minimum value. In Comparative Example 4 which does not have the configuration of the present invention showing the maximum value (MFRmax) within 100 hours after that, the effect of reducing the amount of die adhesion cannot be obtained, and the frequency of occurrence of gels and blisters multiple times a day Increased rapidly and productivity was inferior.

  Further, in Comparative Example 5 of the present application having the same configuration as that of Example 1 of the above-mentioned Japanese Patent Laid-Open No. 10-67898, the MFRmax / MFR0 exceeds 45, so that the coloration resistance is poor and the adhesiveness is insufficient. In addition, the generation of gels and blisters increased as the operation was continued for a long time.

Claims (7)

A resin composition comprising an ethylene-vinyl alcohol copolymer, and when heated at 220 ° C. in a nitrogen atmosphere, the MFR (230 ° C., 10.9 kg load) of the resin composition is within 10 hours from the start of heating. Shows the minimum value, shows the maximum value (MFRmax) within 100 hours after showing the minimum value,
0.05 to 4 μmol / g of carboxylic acid (A),
50 to 500 ppm of sodium salt (B) in terms of metal element, and
Magnesium salt (C) 10 to 120 ppm in terms of metal element
Containing 0.005 to 1 part by weight of a lubricant with respect to 100 parts by weight of an ethylene-vinyl alcohol copolymer,
The following formulas (1) and (2) are satisfied,
A resin composition, wherein the lubricant is a higher fatty acid amide.
1.7 ≦ MFRmax / MFR0 ≦ 3.1 (1)
0.9 ≦ (a1) / (A) ≦ 1.0 (2)
However,
MFRmax: Maximum value of MFR (230 ° C., 10.9 kg load) of the resin composition when the resin composition is heated at 220 ° C. in a nitrogen atmosphere MFR0: MFR of the resin composition not subjected to heat treatment (230 ℃, 10.9kg load)
(A): Total content of carboxylic acid (A) and its salt (μmol / g)
(A1): content of carboxylic acid (a1) having a molecular weight of 75 or more and a salt thereof (μmol / g)   The resin composition according to claim 1, comprising 10 to 500 ppm of the phosphate compound (D) in terms of phosphate radical.   The resin composition according to claim 1 or 2, wherein the boron compound (E) is contained in an amount of 50 to 2000 ppm in terms of boron element. Including a carboxylic acid (a1) having a molecular weight of 75 or more as the carboxylic acid (A),
The resin composition according to any one of claims 1 to 3, wherein the carboxylic acid (a1) having a molecular weight of 75 or more is a hydroxycarboxylic acid. Including a carboxylic acid (a1) having a molecular weight of 75 or more as the carboxylic acid (A),
The resin composition according to any one of claims 1 to 3, wherein the carboxylic acid (a1) having a molecular weight of 75 or more is lactic acid.   A resin composition pellet formed by adhering 0.005 to 0.5 parts by weight of a lubricant to 100 parts by weight of the resin composition on the outer surface of the pellet made of the resin composition according to any one of claims 1 to 5. .   A multilayer structure comprising a thermoplastic resin laminated on at least one side of a layer made of the resin composition according to claim 1.

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