JP7388184B2 - Ethylene-vinyl alcohol copolymer resin composition, multilayer structure and packaging - Google Patents

Description

The present invention relates to an ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH") resin composition, and more specifically to EVOH, which has excellent impact resistance, light resistance, and adhesive strength. This invention relates to a resin composition.

EVOH has excellent gas barrier properties, including oxygen barrier properties, because the abundant hydroxyl groups in its molecular chains form strong hydrogen bonds to form crystalline parts, and these crystalline parts prevent oxygen from entering from the outside. This shows that. This EVOH is generally used in the middle layer of a laminate made of resins, and is used in various packaging bodies.

As mentioned above, EVOH has excellent gas barrier properties, but because it has abundant hydroxyl groups in its molecular chain and has a high degree of crystallinity, it tends to be brittle, and the EVOH layer in the package may crack or pinholes may occur due to impact, etc. It may be destroyed by doing so.

Therefore, for the purpose of improving the impact resistance of EVOH, for example, Patent Documents 1 and 2 disclose a laminated package having a resin composition layer made of EVOH and an ethylene-vinyl acetate copolymer. Further, Patent Documents 3 and 4 disclose a laminate having a resin composition layer made of a partially saponified product of EVOH and an ethylene-vinyl acetate copolymer.

Additionally, because the multilayer structure using EVOH has excellent transparency, it transmits not only visible light but also ultraviolet rays, which causes problems such as the contents being packaged deteriorating due to ultraviolet rays. Sometimes I put it away. In particular, when a multilayer structure is used as a food packaging material, the food contents are exposed to UV-B and UV-C ultraviolet rays in the wavelength range of less than 320 nm, resulting in significant deterioration of the food itself. It has been known.

Therefore, by incorporating a water-soluble ultraviolet absorber into a resin film such as polyvinyl alcohol, which is a type of film with gas barrier properties, it has excellent transparency and prevents photodeterioration of the contents due to ultraviolet transmission. Techniques to prevent this have been proposed (for example, see Patent Document 5).

Japanese Unexamined Patent Publication No. 61-220839 Japanese Unexamined Patent Publication No. 152847/1984 Japanese Unexamined Patent Publication No. 1-279949 Japanese Patent Application Publication No. 3-192140 Japanese Unexamined Patent Publication No. 51-132259

However, in Patent Documents 1 to 4, a portion of EVOH is replaced with a resin other than EVOH, so the proportion of EVOH in the resin composition decreases, and the gas barrier properties derived from EVOH tend to decrease.
In addition, the technologies described in Patent Documents 1 to 4 have excellent impact resistance (the EVOH layer is difficult to break), but also have excellent transparency, so when used as a packaging material for a long period of time, the contents ( UV rays may cause deterioration of foods (such as foods).

In addition, in the technology described in Patent Document 5, when used as a packaging material for a long period of time, the ultraviolet absorber bleeds out due to the contents, resulting in deterioration of appearance, decrease in ultraviolet absorption effect, and generation of odor. Problems such as these may occur, and further improvements have been requested.
In addition, the technology described in Patent Document 5 has insufficient impact resistance against drops and collisions during long-term transportation or handling, and problems such as oxidative deterioration of contents (food, etc.) may occur. .

In recent years, with the spread of Internet shopping and the economic growth of developing countries, the distribution of goods has rapidly become borderless, and the transportation period for foods and medicines has become longer, resulting in increased risk during long-term transportation and during handling. There is a need for a multilayer structure (packaging material) having a layer made of an EVOH resin composition that has high impact resistance against drops and collisions, excellent light resistance, and further excellent adhesive strength and gas barrier properties.

In view of this background, the present invention provides an EVOH resin composition that has excellent impact resistance and light resistance, and also has excellent adhesive strength, even without blending resins other than EVOH.

However, as a result of extensive research in view of the above circumstances, the present inventors discovered that EVOH contains acetic acid and/or its salt, an aliphatic carboxylic acid other than acetic acid, and an element belonging to the d block of period 4 of the long periodic table. By using the above-mentioned metal salt of aliphatic carboxylic acid containing at least one selected metal species in combination with cinnamic acid and/or its salt, a film with excellent impact resistance and adhesive strength and color tone can be obtained. It has been found that an EVOH resin composition having excellent stability and light resistance can be obtained.

In other words, it is generally known that fatty acid metal salts promote the thermal decomposition of EVOH and reduce the impact resistance and color tone of EVOH resin compositions. Those skilled in the art will avoid incorporating fatty acid metal salts into EVOH for the purpose of improvement. However, when the present inventor combined EVOH with acetic acid and/or its salt, an aliphatic carboxylic acid other than acetic acid and its specific metal salt, and cinnamic acid and/or its salt so as to satisfy a specific relationship. , found that its mechanical properties (impact resistance) and color were improved contrary to previous expectations.

As described above, the present invention provides EVOH (A), acetic acid and/or a salt thereof (B), an aliphatic carboxylic acid other than acetic acid (C), and an aliphatic carboxylic acid that is a metal salt of the aliphatic carboxylic acid (C). A resin composition containing an acid metal salt (D), cinnamic acid and/or its salt (E), wherein the metal species of the aliphatic carboxylic acid metal salt (D) corresponds to period 4 of the long periodic table. At least one element selected from the elements belonging to the d block, the acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), cinnamic acid and/or The first gist is an EVOH resin composition in which various contents of the salt (E) satisfy the following formulas (1) to (3) on a weight basis.
[Formula] 0.015≦((D) content in terms of metal ions/(E) content in terms of cinnamate ions)≦50...(1)
[Formula] 0.001≦((D) metal ion equivalent content/(B) acetate ion equivalent content)≦1.30...(2)
[Formula] 0.11≦((D) metal ion equivalent content/(C) carboxylic acid ion equivalent content)≦100...(3)

Further, a multilayer structure having a layer made of an EVOH resin composition according to the first aspect is defined as a second aspect, and a package consisting of a multilayer structure according to the second aspect is defined as a third aspect. .

The EVOH resin composition of the present invention comprises an ethylene-vinyl alcohol copolymer, namely EVOH (A), acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), and the aliphatic carboxylic acid metal salt. (D), a resin composition containing cinnamic acid and/or its salt (E), wherein the metal species of the aliphatic carboxylic acid metal salt (D) is in the 4th period d block of the long periodic table; At least one element selected from the above acetic acid and/or its salt (B), the above aliphatic carboxylic acid (C), the above aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt ( Since the various contents of E) satisfy the following formulas (1) to (3) on a weight basis, it has excellent impact resistance and adhesive strength when formed into a film, and also has good color stability and light resistance. Are better.
[Formula] 0.015≦((D) content in terms of metal ions/(E) content in terms of cinnamate ions)≦50...(1)
[Formula] 0.001≦((D) metal ion equivalent content/(B) acetate ion equivalent content)≦1.30...(2)
[Formula] 0.11≦((D) metal ion equivalent content/(C) carboxylic acid ion equivalent content)≦100...(3)

Further, the content of the cinnamic acid and/or its salt (E) in terms of cinnamic acid ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), and the fat. If the content is 1 to 1000 ppm based on the total content of the group carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E), the color tone will be even more stable. Excellent in sex.

Further, the content of the aliphatic carboxylic acid metal salt (D) in terms of metal ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), the aliphatic carboxylic acid salt (D), and the aliphatic carboxylic acid metal salt (D). When the content is 1 to 500 ppm based on the total content of the acid (C), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E), impact resistance and Excellent adhesive strength.

Further, the content of the aliphatic carboxylic acid (C) in terms of carboxylic acid ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), C), if the content is 0.001 to 450 ppm based on the total content of the aliphatic carboxylic acid metal salt (D) and the cinnamic acid and/or its salt (E), the impact resistance will be further improved. Excellent color stability.

In addition, the content of the acetic acid and/or its salt (B) in terms of acetate ion is the content of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), the aliphatic carbon If the content is 10 to 2000 ppm based on the total content of the acid (C), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E), it will be even more effective when forming a film. It has excellent impact resistance and adhesive strength, as well as excellent color stability.

In addition, the content ratio of the above cinnamic acid and/or its salt (E) in terms of cinnamic acid ion to the content of the above acetic acid and/or its salt (B) in terms of cinnamic acid ion (cinnamic acid of (E) If the ratio (converted ion content/converted acetate ion content of (B)) is 0.0001 to 10000 on a weight basis, the film will have better impact resistance when formed, and will also have better color stability and light resistance. It is also excellent in sex.

In addition, when the elongational viscosity at 210°C and 100S ^-1 of the ethylene-vinyl alcohol copolymer resin composition satisfies the following formula (4), the impact resistance when formed into a film is improved. Excellent.
[Formula] 500≦Elongational viscosity [Pa・s]≦48000...(4)

Furthermore, in the ethylene-vinyl alcohol copolymer resin composition containing boric acid and/or a salt thereof (F), the boric acid and/or salt thereof (F) is copolymer (A), the acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), the cinnamic acid and/or its salt (E), If the boron content is 0.001 to 500 ppm in terms of boron relative to the total content of the boric acid and/or its salt (F), the impact resistance during film formation will be even better, and It also has excellent color stability.

Furthermore, the multilayer structure obtained using the above EVOH resin composition has excellent mechanical properties (impact resistance) and is an excellent multilayer structure with improved color tone reduction and adhesive strength reduction during melt molding. .

Furthermore, since the package of the present invention is composed of the multilayer structure described above, the resulting package also has excellent impact resistance and adhesive strength, as well as excellent color stability.

Hereinafter, the present invention will be explained in detail, but these are examples of desirable embodiments.

The EVOH resin composition of the present invention has EVOH (A) as a main component, acetic acid and/or its salt (B), an aliphatic carboxylic acid other than acetic acid (C), and a metal salt of the aliphatic carboxylic acid (C). It contains an aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E). In the EVOH resin composition of the present invention, the base resin is EVOH (A), and the content of EVOH (A) in the EVOH resin composition is usually 60% by weight or more, preferably 70% by weight or more, It is more preferably 80% by weight or more, particularly preferably 90% by weight or more. Each component will be explained below.
In addition, in this specification, "and/or" means at least one, and in the case of "X and/or Y", it means three types: X only, Y only, and X and Y.

<EVOH(A)>
EVOH (A) used in the present invention is usually a resin obtained by copolymerizing ethylene and a vinyl ester monomer and then saponifying it, and is an ethylene-vinyl alcohol copolymer or an ethylene-vinyl acetate-based It is a water-insoluble thermoplastic resin known as a saponified copolymer. Any known polymerization method may be used, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., but generally solution polymerization using methanol as a solvent is used. The obtained ethylene-vinyl ester copolymer can also be saponified by a known method.

That is, the EVOH (A) used in the present invention mainly consists of ethylene structural units and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units that remain without being saponified. Note that EVOH is also generally referred to as "saponified ethylene-vinyl ester copolymer".

As the vinyl ester monomer, vinyl acetate is typically used because it is easily available on the market and has good efficiency in treating impurities during production. In addition, examples of vinyl ester monomers include vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, etc. and aromatic vinyl esters such as vinyl benzoate. Among these, aliphatic vinyl esters preferably have 3 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms. These are usually used alone, but multiple types may be used simultaneously if necessary.

The content of ethylene structural units in the above EVOH (A) is a value measured based on ISO 14663, and is usually 20 to 60 mol%, preferably 21 to 55 mol%, more preferably 22 to 50 mol%, particularly preferably is 23 to 45 mol%. If the content is too small, gas barrier properties and melt moldability at high humidity tend to decrease, while if the content is too large, gas barrier properties tend to decrease.

The degree of saponification of the vinyl ester component in the above EVOH (A) is a value measured based on JIS K6726 (however, EVOH is a solution uniformly dissolved in a water/methanol solvent), and is usually 90 to 100 mol%. , preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. If the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance, etc. tend to deteriorate.

Further, the melt flow rate (MFR) (210°C, load 2160 g) of the above EVOH (A) is usually 0.5 to 100 g/10 minutes, preferably 1 to 50 g/10 minutes, particularly preferably 3 to 35 g. /10 minutes. If the MFR is too high, film formability tends to decrease. Furthermore, if the MFR is too low, melt extrusion tends to become difficult.

EVOH (A) used in the present invention further contains structural units derived from comonomers shown below, in addition to ethylene structural units and vinyl alcohol structural units (including unsaponified vinyl ester structural units). You can. Examples of the comonomers include α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; 3-buten-1-ol, 4-penten-1-ol, 3-buten-1, Hydroxy group-containing α-olefins such as 2-diol and hydroxy group-containing α-olefin derivatives such as esterified products and acylated products thereof; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2- Hydroxymethylvinylidene diacetates such as methylenepropane, 1,3-dibutyronyloxy-2-methylenepropane; unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides or anhydrides; unsaturated Examples include sulfonic acid or its salt; vinyl silane compound; vinyl chloride; styrene.

Furthermore, as the EVOH (A), it is also possible to use EVOH that has been "post-modified" such as urethanized, acetalized, cyanoethylated, or oxyalkylenated.

Among the above-mentioned modified EVOH (A), EVOH (A) in which a primary hydroxyl group is introduced into the side chain through copolymerization has good secondary formability such as stretching treatment and vacuum/pressure forming. EVOH (A) having a 1,2-diol structure in its side chain is particularly preferred.

Furthermore, the EVOH (A) used in the present invention may be a mixture with other EVOHs, and such other EVOHs include those with different contents of ethylene structural units and those with different degrees of saponification. , those with different melt flow rates (MFR) (210°C, load 2160 g), those with different other copolymerization components, and those with different amounts of modification (for example, the content of structural units containing primary hydroxyl groups in the side chains are different) things), etc.

<Acetic acid and/or its salt (B)>
The EVOH resin composition of the present invention contains acetic acid and/or its salt (B). That is, the EVOH resin composition of the present invention contains at least one selected from the group consisting of acetic acid and acetate.

Specific examples of the acetic acid and/or its salt (B) include acetic acid, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, manganese acetate, copper acetate, cobalt acetate, zinc acetate, etc. These can be used alone or in combination of two or more. Among these, acetic acid, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate are particularly preferred, acetic acid, sodium acetate, and potassium acetate are particularly preferred, and acetic acid and sodium acetate are particularly preferred. Particularly preferred is sodium acetate.

The content of the acetic acid and/or its salt (B) in terms of acetate ion is EVOH (A), acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), and the aliphatic carboxylic acid metal. It is usually 10 to 2000 ppm, preferably 15 to 1500 ppm, particularly preferably 20 to 1000 ppm, particularly preferably 25 to 1000 ppm, based on the total content of salt (D), cinnamic acid and/or its salt (E). It is 650 ppm.
If the content is too small, the adhesive strength tends to decrease due to thermal decomposition products of the aliphatic carboxylic acid metal salt (D), and the effects of the present invention tend not to be sufficiently obtained. , the color tone stability during melt molding tends to deteriorate, and the effects of the present invention tend not to be sufficiently obtained.

The content of acetic acid and/or its salt (B) in terms of acetate ion can be measured by a known analytical method. For example, it can be measured using liquid chromatography mass spectrometry (LC/MS), gas chromatography mass spectrometry (GC/MS), or the like.

<Aliphatic carboxylic acid (C) other than acetic acid>
The EVOH resin composition of the present invention contains an aliphatic carboxylic acid (C) other than acetic acid, and the aliphatic carboxylic acid (C) usually has 3 to 30 carbon atoms, preferably 4 to 22 carbon atoms. , particularly preferably from 5 to 14. When the number of carbon atoms in the aliphatic carboxylic acid (C) is within the above range, the effects of the present invention tend to be more effectively obtained.

Specific examples of the aliphatic carboxylic acid (C) include aliphatic monocarboxylic acids, aliphatic dicarboxylic acids, aliphatic tricarboxylic acids, and the like. More specifically, for example, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, henicosyl acids, saturated aliphatic monocarboxylic acids such as behenic acid, lignoceric acid, montanic acid, melisic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, gluconic acid, mevalonic acid, pantoic acid; linoleic acid, linolenic acid , pinolenic acid, eleostearic acid, isostearic acid, isononanoic acid, 2-ethylhexanoic acid, 2-heptylundecanoic acid, 2-octyldodecanoic acid, palmitoleic acid, sapienoic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid , unsaturated aliphatic monocarboxylic acids such as eicosenoic acid, erucic acid, nervonic acid, and ricinoleic acid; saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid; eicosadienoic acid; Examples include unsaturated aliphatic dicarboxylic acids such as docosadienoic acid; saturated aliphatic tricarboxylic acids such as citric acid, isocitric acid, and aconitic acid. These aliphatic carboxylic acids (D) can be used alone or in combination of two or more. Among these, from the viewpoint of thermal stability (prevention of viscosity increase and fish eye formation during melt molding), aliphatic monocarboxylic acids containing one carboxy group are preferred, and saturated aliphatic monocarboxylic acids are more preferred. Still more preferred are saturated aliphatic monocarboxylic acids having 6 to 22 carbon atoms, particularly preferred are stearic acid, caproic acid, caprylic acid, lauric acid, and behenic acid, particularly preferred are caproic acid and caprylic acid. acid, lauric acid.

The content of the aliphatic carboxylic acid (C) in terms of carboxylic acid ion is EVOH (A), acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), and the aliphatic carboxylic acid metal salt. (D), cinnamic acid and/or its salt (E) is usually 0.001 to 950 ppm, preferably 0.001 to 450 ppm, more preferably 0.01 to 360 ppm. It is particularly preferably 0.1 to 250 ppm, particularly preferably 0.5 to 200 ppm.
If the content is too small, the thermal stability of the aliphatic carboxylic acid metal salt (D) will be insufficient, and as a result, the effects of the present invention tend not to be sufficiently obtained. If the content is too large, melting may occur. The color stability during molding tends to deteriorate, and the aliphatic carboxylic acid (C) itself acts as a plasticizer, making it difficult to obtain the effects of the present invention sufficiently.

The content ratio of the acetic acid and/or its salt (B) in terms of acetate ion to the content of the aliphatic carboxylic acid (C) in terms of carboxylate ion (acetate ion of acetic acid and/or its salt (B)) The content (converted content/carboxylic acid ion equivalent content of aliphatic carboxylic acid (C)) is usually 0.0001 to 10000, preferably 0.001 to 5000, and more preferably 0.1 to 5000 on a weight basis. 1000, particularly preferably 1 to 800, particularly preferably 1 to 600.
When the content ratio is within the above range, the effects of the present invention tend to be more pronounced; when it is smaller than the above range, the color stability during melt molding may be insufficient, or the adhesive strength may be insufficient. If it is larger than the above range, the effects of the present invention tend not to be sufficiently obtained.

<Aliphatic carboxylic acid metal salt (D)>
The EVOH resin composition of the present invention contains an aliphatic carboxylic acid metal salt (D) which is a metal salt of an aliphatic carboxylic acid (C) other than acetic acid.

The metal species of the aliphatic carboxylic acid metal salt (D) must be an element belonging to the fourth period d block in the long period periodic table. Among these, chromium, cobalt, nickel, copper, and zinc are preferred, and zinc is particularly preferred because it provides particularly excellent effects and is inexpensive and easily available.

Although it is not clear why the excellent effects can be obtained by using the aliphatic carboxylic acid metal salt (D), it is clear that the metal species of the aliphatic carboxylic acid metal salt (D) is in the 4th period d block of the long period periodic table. By being at least one element selected from the elements belonging to It is assumed that mechanical properties (impact resistance) are improved as a result of highly uniform higher-order structures such as molecular orientation and crystal structure.

As the anion species of the aliphatic carboxylic acid metal salt (D), those exemplified as the aliphatic carboxylic acid (C) other than acetic acid can be used, but in the present invention, the aliphatic carboxylic acid metal salt (D It is important that the anion species of ) and the aliphatic carboxylic acid (C) are the same species. Because the anion type of the aliphatic carboxylic acid metal salt (D) and the aliphatic carboxylic acid (C) are the same type, the EVOH resin has excellent impact resistance and has higher color stability even when melt molded. It can be a composition.
In addition, when the EVOH resin composition of the present invention contains a plurality of aliphatic carboxylic acids (C) or a plurality of aliphatic carboxylic acid metal salts (D), at least one type of aliphatic carboxylic acid (C) and aliphatic carboxylic acid It is sufficient that the anion species of the group carboxylic acid metal salt (D) are the same.

Although it is not clear why an excellent effect is obtained when the anion species of the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (D) are the same, it is clear that a specific amount of the aliphatic carboxylic acid ( By using C) and the aliphatic carboxylic acid metal salt (D) together, the dispersibility of the aliphatic carboxylic acid metal salt (D) can be significantly improved, and more excellent effects of the present invention can be obtained. It is assumed that. Furthermore, the aliphatic carboxylic acid (C) is thought to interact with the metal species of the aliphatic carboxylic acid metal salt (D) and exist in a metal complex-like state. Since the anion species is the same as the aliphatic carboxylic acid (C), it can exist in a more energetically stable state, and has excellent thermal stability even when melt molded, resulting in an EVOH resin composition. It is assumed that the mechanical properties (impact resistance) of the object are improved.

Furthermore, when the number of carbon atoms in the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (D) is usually 3 to 30, preferably 4 to 22, particularly preferably 5 to 14, the Mechanical properties (impact resistance) tend to be improved. Although the reason for this is not clear, when the number of carbon atoms in the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (D) is within the above range, the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid Since the acid metal salt (D) becomes more uniformly dispersed in the EVOH resin composition, it is presumed that the mechanical properties (impact resistance) of the EVOH resin composition are improved more significantly as a result.

Further, when the aliphatic carboxylic acid metal salt (D) is used alone, although the impact resistance is improved, the adhesive strength tends to decrease. Although the reason for this is not clear, the thermal stability of the above aliphatic carboxylic acid metal salt (D) alone is insufficient, and the thermal decomposition of the aliphatic carboxylic acid metal salt (D) generated during melt molding. It is thought that the adhesive strength was reduced by the material. On the other hand, in the present invention, by using the aliphatic carboxylic acid metal salt (D) together with acetic acid and/or its salt (B), the thermal decomposition product of the aliphatic carboxylic acid metal salt (D) can be converted into acetic acid and/or a salt thereof. Alternatively, it is presumed that the salt (B) is captured and dispersed, thereby suppressing the decrease in adhesive strength.

The content of the aliphatic carboxylic acid metal salt (D) in terms of metal ion is EVOH (A), acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal It is usually 1 to 500 ppm, preferably 5 to 300 ppm, particularly preferably 10 to 250 ppm, particularly preferably Preferably it is 30 to 200 ppm. If the content of the aliphatic carboxylic acid metal salt (D) is too low, the effects of the present invention tend not to be sufficiently obtained, and if the content is too high, the adhesive strength may decrease or the color tone during melt molding may decrease. Stability tends to decrease easily.

The content of the aliphatic carboxylic acid (C) in terms of carboxylic acid ions and the content of the aliphatic carboxylic acid metal salt (D) in terms of metal ions can be measured by a known analytical method. . For example, it can be determined by the following methods alone or by combining them.
(i) Content of aliphatic carboxylic acid metal salt (D) in terms of metal ions: Accurately weigh the dried sample, place it in a constant weight platinum evaporation dish, carbonize it with an electric heater, and then heat it with a gas burner. Then, burn it until no smoke comes out, then place the above platinum evaporating dish in an electric furnace and raise the temperature to completely incinerate it. After cooling this, add hydrochloric acid and pure water to the ash, heat it with an electric heater to dissolve it, pour it into a volumetric flask, and make the volume constant with pure water to prepare a sample for atomic absorption spectrometry. By quantitatively analyzing the amount of metal in this sample for atomic absorption spectrometry using atomic absorption spectrometry, the content of the aliphatic carboxylic acid metal salt (D) in terms of metal ions can be determined.
(ii) Content of aliphatic carboxylic acid (C) in terms of carboxylic acid ion: First, using liquid chromatography mass spectrometry (LC/MS) or gas chromatography mass spectrometry (GC/MS), The content (Cx) of the aliphatic carboxylic acid (C) and its metal salt (D) in terms of carboxylic acid ion in the EVOH resin composition is determined. Thereafter, the content (Cy) of the aliphatic carboxylic acid metal salt (D) in terms of carboxylic acid ions is calculated from the content of the aliphatic carboxylic acid metal salt (D) in terms of metal ions. Then, the total content (Cx) of the aliphatic carboxylic acid (C) and its metal salt (D) in terms of carboxylic acid ion, and the content (Cx) of the aliphatic carboxylic acid metal salt (D) in terms of carboxylic acid ion ( The content of aliphatic carboxylic acid (C) in terms of carboxylic acid ion can be determined from the difference ((Cx) - (Cy)) in Cy).

<Cinnamic acid and/or its salt (E)>
In the present invention, it contains cinnamic acid and/or its salt (E). That is, the EVOH resin composition of the present invention contains at least one selected from the group consisting of cinnamic acid and cinnamic acid salts.

Examples of the cinnamic acid used in the present invention include cis-cinnamic acid and trans-cinnamic acid, and from the viewpoints of stability and cost, trans-cinnamic acid is preferably used. Examples of the cinnamate include alkali metal salts of cinnamate such as lithium cinnamate, sodium cinnamate, and potassium cinnamate; alkaline earth metal salts of cinnamate such as magnesium cinnamate, calcium cinnamate, and barium cinnamate. can be mentioned. These cinnamic acids and/or salts thereof can be used alone or in combination of two or more. Among these, it is preferable to use trans-cinnamic acid alone.

The content of the above cinnamic acid and/or its salt (E) in terms of cinnamic acid ion is EVOH (A), acetic acid and/or its salt (B), the above aliphatic carboxylic acid (C), the above aliphatic carbon It is usually 1 to 1200 ppm, preferably 1 to 1000 ppm, more preferably 10 to 800 ppm, and more preferably 1 to 1000 ppm, based on the total content of acid metal salt (D), cinnamic acid and/or its salt (E). It is preferably 15 to 500 ppm, particularly preferably 50 to 300 ppm, particularly preferably 100 to 200 ppm. If the content is too low, light resistance tends to decrease, and if the content is too high, odor generation during melt molding tends to become a problem.

The EVOH resin composition of the present invention has a content ratio ((D) of the aliphatic carboxylic acid metal salt (D) in terms of metal ions to the content of the cinnamic acid and/or its salt (E) in terms of cinnamic acid ions. /(E)) satisfies the following formula (1) on a weight basis.
[Formula] 0.015≦((D) content in terms of metal ions/(E) content in terms of cinnamate ions)≦50...(1)
Preferably 0.075≦((D)/(E))≦40, particularly preferably 0.15≦((D)/(E))≦30, particularly preferably 0.2≦((D)/ (E))≦20. When the value is within the above range, the effects of the present invention tend to be more pronounced, and when it is outside the above range, the effects of the present invention tend not to be sufficiently obtained.

The EVOH resin composition of the present invention has a content ratio ((D)/( B)) satisfies the following formula (2) on a weight basis.
[Formula] 0.001≦((D) metal ion equivalent content/(B) acetate ion equivalent content)≦1.30...(2)
Preferably 0.005≦((D)/(B))≦1.1, more preferably 0.005≦((D)/(B))≦1.0, even more preferably 0.01≦( (D)/(B))≦0.8, particularly preferably 0.04≦((D)/(B))≦0.48, particularly preferably 0.05≦((D)/(B) )≦0.45. When such a value is within the above range, the effects of the present invention tend to be obtained more significantly, when it is smaller than the above range, the effects of the present invention tend not to be sufficiently obtained, and when it is larger than the above range, Color stability during melt molding tends to be insufficient, and adhesive strength tends to be insufficient.

The EVOH resin composition of the present invention has a content ratio ((D)/(C )) satisfies the following formula (3) on a weight basis.
[Formula] 0.11≦((D) metal ion equivalent content/(C) carboxylic acid ion equivalent content)≦100...(3)
Preferably 0.13≦((D)/(C))≦90, particularly preferably 0.15≦((D)/(C))≦80, particularly preferably 0.2≦((D)/( C))≦70. When this value is within the above range, the effects of the present invention tend to be more noticeable, and when it is smaller than the above range, the color stability during melt molding may be insufficient, or the effects of the present invention may not be sufficiently achieved. If it is larger than the above range, the color tone stability during melt molding tends to be insufficient or the moldability tends to be insufficient.

The content of the acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E) is based on the formula Although it is not clear why excellent effects can be obtained by satisfying (1) to (3), a specific amount of the aliphatic carboxylic acid having the same anion species as the aliphatic carboxylic acid metal salt (D) (C) has the effect of increasing the dispersibility and thermal stability of the aliphatic carboxylic acid metal salt (D), but if the content of the aliphatic carboxylic acid (C) is too large, the aliphatic carboxylic acid It is presumed that because (C) itself acted as a plasticizer, the effect of the present invention (impact resistance improvement effect) could not be sufficiently obtained. In addition, a specific amount of acetic acid and/or its salt (B) has the effect of capturing the thermal decomposition products of the aliphatic carboxylic acid metal salt (D) and suppressing a decrease in adhesive strength; If the content of the salt (B) is too large, the thermal stability of EVOH (A) will be significantly reduced, the color stability will be likely to be reduced, and the effect of the present invention (impact resistance improvement effect) may not be sufficiently achieved. It is assumed that it will not be possible. In addition, the specific amount of cinnamic acid and/or its salt (E) has an excellent ultraviolet absorption effect, and the aliphatic carboxylic acid metal salt that was not completely captured by the acetic acid and/or its salt (B). It is presumed that cinnamic acid and/or its salt (E) traps the thermal decomposition product of (D) and the thermal decomposition product of the EVOH (A), thereby having the effect of suppressing the deterioration of color tone. On the other hand, if the content of cinnamic acid and/or its salt (E) is too large, the effect of the present invention (impact resistance improvement effect) may be reduced due to thermal decomposition of cinnamic acid and/or its salt (E) itself. It is presumed that this may result in not being able to obtain a sufficient amount, or that color tone stability tends to deteriorate.

Further, from the viewpoint of impact resistance, the EVOH resin composition of the present invention preferably has an elongational viscosity at 210° C. and 100 S ⁻¹ that satisfies the following formula (4).
[Formula] 850≦Elongational viscosity [Pa・s]≦48000...(4)
More preferably 900≦elongational viscosity [Pa·s]≦30,000, particularly preferably 950≦elongational viscosity [Pa·s]≦20,000. When the value is within the above range, the effects of the present invention tend to be more pronounced; when the value is smaller than the above range, the effects of the present invention tend not to be sufficiently obtained; and when it is larger than the above range, melting The moldability during molding tends to be insufficient.

Although it is not clear why the elongational viscosity at 210°C and 100 S ^-1 of the EVOH resin composition of the present invention satisfies formula (4), excellent effects can be obtained. The elongational viscosity at ℃ and 100 S ^-1 satisfies formula (4), so that the intertwined structure of EVOH molecular chains appropriately formed in the EVOH resin composition becomes stable when the EVOH resin composition is multilayer coextruded. In addition, since the formation of higher-order structures such as molecular orientation and crystal structure of the EVOH resin composition is more significantly promoted, it is presumed that the mechanical properties (impact resistance) are significantly improved as a result.

<Evaluation method for elongational viscosity (Pa・s) of EVOH resin composition>
The extensional viscosity (Pa・s) of the EVOH resin composition of the present invention at 210° C. and 100 S ⁻¹ was determined using the Cogswell equation [Polymer Engineering Science, Vol. 12, pp. 64-73 (1972)] using a capillary rheometer. ], and can be determined by performing measurements under the following conditions.

That is, the extensional viscosity (η _e ) and extensional strain rate (dε/dt) are expressed by the following equations (5) to (7) proposed by Cogswell (Polymer Engineering Science, Vol. 12, pp. 64-73 (1972)). ).
η _e = [9(n+1) ² P ₀ ² ]/[32η _s (dγ/dt) ² ]...Equation (5)
dε/dt=4σ _s (dγ/dt)/[3(n+1)P ₀ ]...Equation (6)
σ _s =k(dγ/dt) ⁿ ...Formula (7)
Here, η _e is the extensional viscosity, η _s is the shear viscosity, dγ/dt is the shear strain rate, dε/dt is the extensional strain rate, σ _s is the shear stress, k is a constant, and the index n is the melt fracture or slip stick. It is determined by fitting with a quadratic function, assuming that the shear stress and the shear strain rate follow a power law in the shear rate region (100≦dγ/dt≦1000) where dγ/dt does not occur. P ₀ is a pressure loss occurring in a die with a capillary length of 0, and is determined by Caglay correction of measurement results using two or more capillaries with different lengths.
Measuring device: RHEOGRAPH 20 manufactured by Gottfert
Measurement temperature: 210℃
Long die: length 10mm, diameter 1mm, inlet angle 180°
Short die: length 0.2mm, diameter 1mm, inlet angle 180°

<Boric acid and/or its salt (F)>
The EVOH resin composition of the present invention preferably contains the boric acid and/or its salt (F). That is, the EVOH resin composition of the present invention preferably contains at least one selected from the group consisting of boric acid and boric acid salts.

The above-mentioned boric acid and/or its salt (F) usually includes boric acid, metal salts of boric acid, such as calcium borate, cobalt borate, zinc borate (zinc tetraborate, zinc metaborate, etc.), Aluminum/potassium borate, ammonium borate (ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate, etc.), cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.), potassium borate ( Potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate, etc.), silver borate (silver metaborate, silver tetraborate, etc.), copper borate (cupric borate, etc.) , copper metaborate, copper tetraborate, etc.), sodium borate (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.), lead borate (lead metaborate, lead hexaborate, etc.), nickel borate (nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate, etc.), barium borate (barium orthoborate, barium metaborate, diborate, etc.) barium borate, barium tetraborate, etc.), bismuth borate, magnesium borate (magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc.), manganese borate ( Manganous borate, manganese metaborate, manganese tetraborate, etc.), lithium borate (lithium metaborate, lithium tetraborate, lithium pentaborate, etc.), as well as borax, carnite, inyoite, cholinite , boric acid minerals such as swanite, xiberite, etc., and among them, borax, boric acid, sodium borate, potassium borate, zinc borate, calcium borate, and magnesium borate are preferred, and particularly preferably , boric acid, sodium borate, zinc borate, particularly preferably boric acid.

The content of the above boric acid and/or its salt (F) in terms of boron is EVOH (A), acetic acid and/or its salt (B), aliphatic carboxylic acid other than acetic acid (C), aliphatic carboxylic acid Usually 0.001 to 1000 ppm, preferably 0.001 to 600 ppm, based on the total content of metal salt (D), cinnamic acid and/or its salt (E), and boric acid and/or its salt (F). and more preferably 0.001 to 500 ppm, even more preferably 0.01 to 400 ppm, particularly preferably 0.05 to 330 ppm, even more preferably 0.1 to 250 ppm, particularly preferably 1 to 120 ppm. .
If the content is too small, the effect of the present invention (impact resistance improvement effect) tends not to be sufficiently obtained, and if it is too large, the color tone may deteriorate, fish eyes may occur frequently during multilayer film formation, and There is a tendency that the effect of the invention (impact resistance improvement effect) cannot be sufficiently obtained.

Furthermore, although it is not clear why excellent effects can be obtained by using a specific amount of boric acid and/or its salt (F), boric acid and/or its salt (F) dispersed in the EVOH resin composition interacts with the EVOH molecular chains to form a crosslinked structure between the EVOH molecular chains, and when the EVOH resin composition is coextruded into multiple layers, higher-order structures such as molecular orientation and crystal structure of the EVOH resin composition It is assumed that the mechanical properties (impact resistance) are significantly improved as a result.
Further, the thermal decomposition product of the aliphatic carboxylic acid metal salt (D) and the thermal decomposition product of the EVOH (A) that could not be captured by the acetic acid and/or its salt (B) can be removed using boric acid and/or It is presumed that the salt (F) traps and suppresses the deterioration of color tone.

The content of the boric acid and/or its salt (F) in terms of boron can be measured by a known analytical method. For example, after wet decomposition of an EVOH resin composition, a fixed volume of the EVOH resin composition is used as a test solution, and the amount of boron can be determined by inductively coupled plasma emission spectrometry (ICP-AES).

<Other thermoplastic resins>
The EVOH resin composition of the present invention contains, as a resin component, other thermoplastic resins in addition to EVOH (A) within a range that is usually 30% by weight or less based on EVOH (A). You can.

Examples of the other thermoplastic resins include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ionomers, ethylene-propylene copolymers, polypropylene, polybutene, polypentene, and other olefins alone or Broadly defined polyolefin resins such as copolymers, polycyclic olefins, or graft-modified mono or copolymers of these olefins with unsaturated carboxylic acids or their esters, polystyrene resins, polyesters, polyamide resins, copolymers, etc. Examples include polymerized polyamide resins, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, chlorinated polyethylene, and chlorinated polypropylene.

The α-olefin of the polyolefin resin mentioned above may be a plant-derived α-olefin derived from bioethanol, or a non-vegetable α-olefin, that is, a petroleum-derived α-olefin, or a combination of two of these may be used. May be used. Since a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resin can be easily adjusted by manufacturing using these. By using plant-derived α-olefin, the biomass content of the final product can be further increased, and the burden on the environment can be reduced.

As a method for producing plant-derived ethylene and plant-derived α-olefins, bioethanol is produced by fermenting sugar solution and starch obtained from plants such as sugar cane, corn, and sweet potatoes using microorganisms such as yeast, according to conventional methods. Then, by heating this in the presence of a catalyst, plant-derived ethylene and plant-derived α-olefins (1-butene, 1-hexene, etc.) can be obtained by an intramolecular dehydration reaction or the like. Next, using the obtained plant-derived ethylene and plant-derived α-olefin, a plant-derived polyethylene resin can be produced in the same manner as in the production of petroleum-derived polyethylene resin.

Methods for producing plant-derived ethylene, plant-derived α-olefins, and plant-derived polyethylene resins are described in detail in, for example, Japanese Patent Publication No. 2011-506628. Examples of the plant-derived polyethylene resin suitably used in the present invention include Green PE manufactured by Braskem S.A. and the like.

In particular, when a multilayer structure is produced using the EVOH resin composition of the present invention and used as a food packaging material, the EVOH layer is eluted at the edges of the packaging material after hot water treatment of the packaging material. In order to prevent this, it is preferable to blend a polyamide resin. Polyamide-based resins are capable of forming a network structure through the interaction of amide bonds with at least one of the OH group and ester group of EVOH, thereby preventing elution of the EVOH layer during hot water treatment. I can do it. Therefore, when the EVOH resin composition of the present invention is used as a packaging material for retort food or boiled food, it is preferable to incorporate a polyamide resin.

As the above-mentioned polyamide resin, known ones can be used.
Specifically, for example, polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecanamide (nylon 11), polylauryllactam (nylon 12) ), among which polycapramide (nylon 6) is preferred. Copolymerized polyamide resins include polyethylene diamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), and polyhexamethylene sebacamide (nylon 46). 610), polyhexamethylene dodecamide (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam/lauryllactam copolymer (nylon 6/12), caprolactam /ω-aminononanoic acid copolymer (nylon 6/9), caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/66), lauryl lactam/hexamethylene diammonium adipate copolymer (nylon 12/66), Ethylenediamine adipamide/hexamethylene diammonium adipate copolymer (nylon 26/66), caprolactam/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 66/610), ethylene ammonium adipate/hexamethylene Aliphatic polyamides such as diammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 6/66/610), polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymethaxylylene adipamide, hexamethylene isophthal Aromatic polyamides such as amide/terephthalamide copolymers, poly-P-phenylene terephthalamide, poly-P-phenylene 3-4' diphenyl ether terephthalamide, amorphous polyamides, and methylene benzylamine , those modified with aromatic amines such as meta-xylylene diamine, and meta-xylylene diammonium adipate. Alternatively, it may be a terminal-modified polyamide resin, preferably a terminal-modified polyamide resin.

<Other additives>
The EVOH resin composition of the present invention is generally added to the EVOH resin composition within a range that does not impair the effects of the present invention (for example, usually 10% by weight or less, preferably 5% by weight or less of the EVOH resin composition). Additives to be blended, such as heat stabilizers, antioxidants, antistatic agents, colorants, ultraviolet absorbers, lubricants (e.g., saturated aliphatic amides (e.g., stearic acid amide, etc.), unsaturated fatty acid amides (e.g., oleic acid amide, etc.), bis fatty acid amides (e.g., ethylene bisstearic acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene with a molecular weight of about 500 to 10,000, or low molecular weight polypropylene, etc.), plasticizers (e.g., ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), light stabilizers, surfactants, antibacterial agents, desiccants, insoluble inorganic salts (e.g., hydrotalcite, etc.), fillers (e.g., inorganic fillers, etc.) ), anti-blocking agents, flame retardants, cross-linking agents, foaming agents, crystal nucleating agents, antifogging agents, biodegradation additives, silane coupling agents, oxygen absorbers, phosphoric acid and/or its salts, conjugated polyene compounds, Known additives such as enediol group-containing substances (for example, phenols such as propyl gallate) and aldehyde compounds (for example, unsaturated aldehydes such as crotonaldehyde) may be contained. These can be used alone or in combination of two or more.

Specific examples of the above-mentioned phosphoric acid and/or its salts include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, phosphoric acid Examples include calcium monohydrogen, calcium dihydrogen phosphate, tricalcium phosphate, magnesium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, zinc hydrogen phosphate, barium hydrogen phosphate, manganese hydrogen phosphate, etc. , these can be used alone or in combination of two or more. Among these, phosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium dihydrogen phosphate, and zinc hydrogen phosphate are preferred, and phosphoric acid and sodium dihydrogen phosphate are particularly preferred. , calcium dihydrogen phosphate, magnesium dihydrogen phosphate, and particularly preferably phosphoric acid.

The content of the above phosphoric acid and/or its salt in terms of phosphorus is EVOH (A), acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), Generally, 900 ppm or less is preferable, more preferably 0.01 to 700 ppm, and even more particularly preferably 0.1 to the total content of cinnamic acid and/or its salt (E), phosphoric acid and/or its salt. 500 ppm, particularly preferably 1 to 300 ppm.

The above-mentioned conjugated polyene compound has a structure in which carbon-carbon double bonds and carbon-carbon single bonds are connected alternately, and the number of carbon-carbon double bonds is 2 or more, so-called conjugated double bonds. It is a compound with Conjugated polyene compounds are conjugated dienes, which have a structure in which two carbon-carbon double bonds and one carbon-carbon single bond are alternately connected, and three carbon-carbon double bonds and two carbon- It may be a conjugated triene, which has a structure in which carbon single bonds are alternately connected, or a conjugated polyene compound, which has a structure in which a greater number of carbon-carbon double bonds and carbon-carbon single bonds are alternately connected. . However, if the number of conjugated carbon-carbon double bonds is 8 or more, there is a concern that the molded product will be colored by the color of the conjugated polyene compound itself, so if the number of conjugated carbon-carbon double bonds is 7 or less, A polyene is preferred. Further, the above-mentioned conjugated double bonds consisting of two or more carbon-carbon double bonds may be present in one molecule without being conjugated with each other. For example, compounds having three conjugated trienes in the same molecule, such as tung oil, are also included in conjugated polyene compounds.

Specific examples of conjugated polyene compounds include conjugated diene compounds having two carbon-carbon double bonds such as isoprene, myrcene, farnesene, cembrene, sorbic acid, sorbic acid ester, sorbate, and abietic acid; 1,3, Conjugated triene compounds having three carbon-carbon double bonds such as 5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol; cyclooctatetraene, Examples include conjugated polyene compounds having four or more carbon-carbon double bonds, such as 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid. These conjugated polyene compounds may be used alone or in combination of two or more.

The content of the above conjugated polyene compound is EVOH (A), acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt ( E) is usually 0.01 to 10,000 ppm, preferably 0.1 to 1,000 ppm, particularly preferably 0.5 to 500 ppm, based on the total amount of the conjugated polyene compound.

The above-mentioned heat stabilizers include organic acids such as propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, and behenic acid (however, the above-mentioned When organic acids are used as aliphatic carboxylic acids (C), they are not included in the heat stabilizer.) Or alkali metal salts (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.) of the above organic acids ) etc. These can be used alone or in combination of two or more.

<Method for producing EVOH resin composition>
The method for producing the EVOH resin composition of the present invention is not particularly limited, and examples thereof include the methods shown in (I) to (IV) below.
(I) EVOH (A) pellets containing acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) A method of dry blending by blending at least one selected from the group in a predetermined ratio (dry blend method).
(II) Pellet of EVOH (A) consisting of acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) A method (immersion method) in which pellets are dried after being immersed in a solution containing at least one selected from the group.
(III) From acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) during melt-kneading of EVOH (A) A method (melt kneading method) of blending at least one selected from the group consisting of: and then producing pellets.
(IV) Acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) in a solution containing EVOH (A) A method of adding and mixing at least one selected from the group consisting of, and then removing the solvent in the solution (solution mixing method).

Among these, acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt are added to the EVOH (A) pellets of (I). A method of blending at least one member selected from the group consisting of (E) in a predetermined proportion and dry blending (dry blending method) is practical and industrially preferable in terms of productivity and economy. Note that the above methods may be used in combination. Furthermore, when adding the other additives mentioned above, an EVOH resin composition containing the other additives can be obtained by following the methods (I) to (IV) above.

As the dry blending means in the method (I) above, for example, known mixing devices such as a rocking mixer, a ribbon blender, a line mixer, etc. can be used.

In dry blending in the method (I) above, acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) In order to improve the adhesion of at least one component selected from the group consisting of If the moisture content is too low, acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D ), cinnamic acid and/or its salt (E) tends to easily fall off, resulting in uneven adhesion distribution. Conversely, if it is too large, it is selected from the group consisting of acetic acid and/or its salts (B), aliphatic carboxylic acids (C), aliphatic carboxylic acid metal salts (D), and cinnamic acid and/or its salts (E). At least one species tends to aggregate and the adhesion distribution becomes non-uniform.

The moisture content of the EVOH (A) pellets referred to herein is measured and calculated by the following method.
[Measurement method of moisture content]
After weighing the EVOH (A) pellets using an electronic balance (W1: unit g), put them in a hot air oven type dryer maintained at 150 ° C., dry them for 5 hours, and then let them cool for 30 minutes in a desiccator. The weight (W2: unit: g) after washing is weighed in the same manner and calculated from the following formula.
[Formula] Moisture content (%) = {(W1-W2)/W1}×100

In addition, in the methods (I) and (II) above, acetic acid and/or its salt (B), aliphatic carboxylic acid (C), and aliphatic carboxylic acid metal salt (D) are added to the outside of the EVOH (A) pellet. , cinnamic acid and/or its salt (E) are obtained.

In the method (III) above, melt-kneading can be carried out using a known melt-kneading device such as a kneader, a router, an extruder, a mixing roll, a Banbury mixer, or a plastomill. It is preferable to melt-knead the mixture at 300°C (more preferably 180 to 280°C) for about 1 minute to 20 minutes, and it is particularly advantageous industrially to use a single-screw or twin-screw extruder because pellets can be easily obtained. It is also preferable to provide a vent suction device, a gear pump device, a screen device, etc., as necessary. In particular, in order to remove moisture and by-products (low molecular weight products, etc. of thermal decomposition), one or more vent holes are provided in the extruder to suck them under reduced pressure, or to prevent oxygen from entering the extruder. By continuously supplying an inert gas such as nitrogen into the hopper, it is possible to obtain an EVOH resin composition of excellent quality with reduced thermal discoloration and thermal deterioration.

In addition, there are no particular limitations on the feeding method to a melt kneading device such as an extruder. A method of dry blending the salt (D), cinnamic acid and/or its salt (E), boric acid and/or its salt (F), and feeding it all at once to an extruder, 2) EVOH (A) to the extruder and melted, solid acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E) , a method of supplying boric acid and/or its salt (F) (solid side feed method), 3) EVOH (A) is supplied to an extruder and melted, and molten acetic acid and/or its salt ( B), method of supplying aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E), boric acid and/or its salt (F) (melt side feed method), among others, method 1) is practical in terms of simplicity of the apparatus, cost of the blend, etc.

Further, as a method for producing pellets after melt-kneading, it is possible to use a known method, and examples thereof include a strand cut method, a hot cut method (aerial cut method, underwater cut method), and the like. From the viewpoint of industrial productivity, the strand cutting method is preferred.

The solvent used in the solution mixing method in the method (IV) above may be a known good EVOH solvent, typically a mixed solvent of water and an aliphatic alcohol having 1 to 4 carbon atoms. A mixed solvent of water and methanol is preferred. During dissolution, heating and pressurization can be applied arbitrarily, and the concentration can also be arbitrarily determined. Acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E), Boric acid and/or its salt (F) may be blended. At this time, acetic acid and/or its salt (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E), boric acid and/or its salt ( F) can be blended in the form of solid, solution, dispersion, etc.
After blending, the uniformly stirred EVOH resin composition solution or paste is pelletized by the above-described known method. In terms of industrial productivity, the underwater cut method is preferred. The obtained pellets are dried by a known method.

The shape of the pellet may be any shape, such as a spherical shape, an oval shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, etc., for example. Usually, it has an oval or cylindrical shape, and from the viewpoint of convenience when used as a molding material later, in the case of an oval shape, the short axis is usually 1 to 6 mm, preferably 2 to 5 mm, and the long axis is is usually 1 to 6 mm, preferably 2 to 5 mm. In the case of a cylindrical shape, the diameter of the bottom surface is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm.

In this way, the EVOH resin composition of the present invention can be obtained.

<Multilayer structure>
The multilayer structure of the present invention has at least one layer made of the EVOH resin composition of the present invention. The layer made of the EVOH resin composition of the present invention (hereinafter simply referred to as "EVOH resin composition layer") can be laminated with other base materials to further increase the strength or impart other functions. can.

As the other base material, thermoplastic resins other than EVOH (hereinafter referred to as "other base resins") are preferably used.

Examples of the other base resins include linear low density polyethylene, low density polyethylene, very low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α -Polyethylene resins such as olefin (α-olefins having 4 to 20 carbon atoms) copolymers, polypropylene, polypropylene resins such as propylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymers, polybutene (unmodified) polyolefin resins such as , polypentene, polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain), and these polyolefins with unsaturated carboxylic acids or their esters. Broadly defined polyolefin resins including modified olefin resins such as graft-modified unsaturated carboxylic acid-modified polyolefin resins, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers Coalescence, polyester resin, polyamide resin (including copolymerized polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated Examples include halogenated polyolefins such as polypropylene, aromatic or aliphatic polyketones, and the like.

Among these, in consideration of hydrophobicity, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferable, and more preferably polyethylene resins, polypropylene resins, and polycyclic olefins. These include polyolefin resins such as polyolefin resins and unsaturated carboxylic acid-modified polyolefin resins, and polyolefin resins are particularly preferred.

The α-olefin of the polyolefin resin mentioned above may be a plant-derived α-olefin derived from bioethanol, or a non-vegetable α-olefin, that is, a petroleum-derived α-olefin, or a combination of two of these may be used. May be used. Since a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resin can be easily adjusted by manufacturing using these. By using plant-derived α-olefin, the biomass content of the final product can be further increased, and the burden on the environment can be reduced.

As a method for producing plant-derived ethylene and plant-derived α-olefins, bioethanol is produced by fermenting sugar solution and starch obtained from plants such as sugar cane, corn, and sweet potatoes using microorganisms such as yeast, according to conventional methods. Then, by heating this in the presence of a catalyst, plant-derived ethylene and plant-derived α-olefins (1-butene, 1-hexene, etc.) can be obtained by an intramolecular dehydration reaction or the like. Next, using the obtained plant-derived ethylene and plant-derived α-olefin, a plant-derived polyethylene resin can be produced in the same manner as in the production of petroleum-derived polyethylene resin.

Methods for producing plant-derived ethylene, plant-derived α-olefins, and plant-derived polyethylene resins are described in detail in, for example, Japanese Patent Publication No. 2011-506628. Examples of the plant-derived polyethylene resin suitably used in the present invention include Green PE manufactured by Braskem S.A. and the like.

The layer structure of the multilayer structure of the present invention is such that the EVOH resin composition layer of the present invention is a (a1, a2, ...), and the other base resin layers are b (b1, b2, ...). In the case, a/b, b/a/b, a1/a2, a/b/a, a1/a2/b, a/b1/b2, a1/a2/a3, b2/b1/a/b1/b2, Any combination such as b1/b2/a1/a2/a3/b3/b4, b2/b1/a1/b1/a1/b1/b2 is possible. Furthermore, even if the configuration of the layers laminated in one lamination direction and the configuration of the layers laminated in the other direction are the same (symmetrical) with respect to any EVOH resin composition layer (a), May be different from each other (asymmetric). Furthermore, even if the thickness of the layer laminated in one lamination direction and the thickness of the layer laminated in the other direction are the same (symmetrical) with respect to any EVOH resin composition layer (a), May be different from each other (asymmetric).
In addition, in the above-mentioned layer structure, an adhesive resin layer may be interposed between each layer as necessary. In the case of a multilayer structure having another base resin layer (that is, a thermoplastic resin layer other than EVOH) on at least one surface of the EVOH resin composition layer of the present invention via an adhesive resin layer, the present invention The effects of this tend to be more effective.
In addition, the EVOH resin composition of the present invention and other base resins or other base resins and adhesive properties obtained by remelting and molding edges and defective products generated in the process of manufacturing the above multilayer structure When the recycling layer containing a mixture of resins is R, b/R/a, a1/R/a2, b1/R/a/b2, b1/R1/a/R2/b2, b1/R1/b2/a1 /a2/a3/b3/R2/b4, b1/a1/R/a2/b2, b1/R1/a1/R2/a2/R3/b2, etc. are also possible. The multilayer structure of the present invention usually has a total number of 2 to 15 layers, preferably 3 to 10 layers.

In the multilayer structure of the present invention, the layer structure of the multilayer structure preferably includes the EVOH resin composition layer of the present invention as an intermediate layer, and other base resin layers are provided as both outer layers of the intermediate layer. Preferably, the unit of the multilayer structure (b/a/b, or b/adhesive resin layer/a/adhesive resin layer/b) is a basic unit, and the multilayer structure includes this basic unit as at least a constituent unit.

As the adhesive resin that is the material for forming the adhesive resin layer, any known adhesive resin can be used, and it may be selected as appropriate depending on the type of thermoplastic resin used for the other base resin layers. A typical example is a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by an addition reaction, a graft reaction, or the like. For example, maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-propylene (block and random) copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, These include modified ethylene-vinyl acetate copolymers, maleic anhydride-modified polycyclic olefin resins, maleic anhydride graft-modified polyolefin resins, and these can be used alone or in combination of two or more.

At this time, the content of unsaturated carboxylic acid or its anhydride is usually 0.001 to 3% by weight, preferably 0.01 to 1% by weight, particularly preferably 0.001 to 3% by weight, based on the total amount of the adhesive resin. .03 to 0.5% by weight. If the amount of modification in the modified product is small, adhesion tends to be insufficient, whereas if it is too much, crosslinking reaction occurs and moldability tends to deteriorate.
These adhesive resins can be blended with EVOH (A), other EVOH, rubber/elastomer components such as polyisobutylene, ethylene-propylene rubber, and even resins for the polyolefin resin layer. In particular, it is also possible to blend a polyolefin resin different from the base polyolefin resin of the adhesive resin.

The other base resin and adhesive resin layer may contain acetic acid and/or its salt used in the present invention within a range that does not impede the spirit of the present invention (for example, 30% by weight or less, preferably 10% by weight or less). (B), aliphatic carboxylic acid (C), aliphatic carboxylic acid metal salt (D), cinnamic acid and/or its salt (E), boric acid and/or its salt (F), as well as conventionally known plasticizers. agents (e.g., ethylene glycol, glycerin, hexanediol, etc.), fillers, clays (e.g., montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants (e.g., alkali metal salts of higher fatty acids with 10 to 30 carbon atoms) , alkaline earth metal salts, higher fatty acid esters (e.g., higher fatty acid methyl esters, isopropyl esters, butyl esters, octyl esters, etc.), higher fatty acid amides (e.g., saturated aliphatic amides such as stearic acid amide, behenic acid amide, etc.) unsaturated fatty acid amides such as oleic acid amide and erucic acid amide, bis fatty acid amides such as ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, ethylene bis lauric acid amide, etc.), low molecular weight polyolefins (e.g. , low molecular weight polyethylene with a molecular weight of about 500 to 10,000, or low molecular weight polypropylene), fluorinated ethylene resin, a nucleating agent, an antiblocking agent, an ultraviolet absorber, a wax, etc. These can be used alone or in combination of two or more.

It is also preferable to mix at least one of the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (D) in the present invention with the resin used in the adhesive resin layer. In particular, when the adhesive resin layer adjacent to the EVOH resin composition layer of the present invention contains an aliphatic carboxylic acid (C) and an aliphatic carboxylic acid metal salt (D), the multilayer structure has even better impact resistance. is obtained.

When producing a multilayer structure by laminating the EVOH resin composition of the present invention with another base resin (including the case where an adhesive resin layer is interposed), the lamination method can be performed by a known method. . For example, a method in which a film, sheet, etc. made of the EVOH resin composition of the present invention is melt-extruded laminated with another base resin; conversely, a method in which the EVOH resin composition of the present invention is melt-extruded laminated on another base resin; A method of co-extruding the EVOH resin composition of the present invention and other base resin, producing a film (layer) made of the EVOH resin composition of the present invention and another base resin (layer), and A method of dry laminating using a known adhesive such as a titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound, or a method of applying a solution of the EVOH resin composition of the present invention on another base resin and then removing a solvent Examples include a method of removing it. Among these, coextrusion is preferred from the viewpoint of cost and environment.

The above-mentioned multilayer structure can be used as it is in various shapes, but it may be subjected to (heating) stretching treatment if necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, simultaneous stretching or sequential stretching may be performed. Further, as the stretching method, a method with a high stretching ratio among roll stretching methods, tenter stretching methods, tubular stretching methods, stretch blowing methods, vacuum-pressure forming methods, etc. can be adopted. The stretching temperature is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, stretchability tends to be poor, and if it is too high, it tends to be difficult to maintain a stable stretched state.

Note that heat setting may be performed on the multilayer structure for the purpose of imparting dimensional stability to the multilayer structure after stretching. Heat setting can be carried out by well-known means, for example, the stretched multilayer structure (stretched film) is heated at a temperature of usually 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds while maintaining a tensioned state. Perform some heat treatment.

In addition, when the multilayer stretched film obtained using the EVOH resin composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting is not performed, and for example, after stretching, The film may be cooled and fixed by blowing cold air on it.

Furthermore, it is also possible to obtain multilayer containers in the form of cups and trays from the multilayer structure of the present invention. As a method for producing a multilayer container, a drawing method is usually adopted, and specific examples thereof include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug-assisted vacuum pressure forming method, and the like. Furthermore, blow molding is used to obtain multilayer containers in the form of tubes and bottles from multilayer parisons (hollow tubular preforms before blowing), and specifically extrusion blow molding (double-head type, moving mold , parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding method, injection blow molding method, biaxial stretch blow molding method (extrusion type cold parison biaxial stretch blow molding method, injection type) (cold parison biaxial stretch blow molding method, injection molding inline biaxial stretch blow molding method, etc.). The multilayer laminate of the present invention may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. as necessary. can be done.

The thickness of the multilayer structure (including a stretched one) of the present invention, and the thickness of the resin composition layer, other base resin layer, and adhesive resin layer that constitute the multilayer structure are determined by the layer structure, the base resin It is set appropriately depending on the type of adhesive resin, the type of adhesive resin, the use and packaging form, the required physical properties, etc.

The thickness of the multilayer structure (including a stretched structure) of the present invention is usually 10 to 5000 μm, preferably 30 to 3000 μm, and particularly preferably 50 to 2000 μm. If the total thickness of the multilayer structure is too thin, gas barrier properties tend to decrease. Furthermore, if the total thickness of the multilayer structure is too thick, the gas barrier properties will be excessive and unnecessary raw materials will be used, which is economically unfavorable. The EVOH resin composition layer of the present invention in the multilayer structure is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and the other base resin layers are usually 5 to 3000 μm, preferably is 10 to 2000 μm, particularly preferably 20 to 1000 μm, and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm. In addition, when there are two or more layers of at least one of the EVOH resin composition layer, adhesive resin layer, and other base resin layer, the above numerical value is the total value of the thickness of the same type of layer. It is.

Furthermore, when there are multiple layers, the thickness ratio between the resin composition layer and other base resin layers (resin composition layer/other base resin layer) in the multilayer structure is The ratio is usually 1/99 to 50/50, preferably 5/95 to 45/55, particularly preferably 10/90 to 40/60. In addition, the thickness ratio between the resin composition layer and the adhesive resin layer (resin composition layer/adhesive resin layer) in the multilayer structure is usually 10 in the case where there are multiple layers, the ratio between the thickest layers. /90 to 99/1, preferably 20/80 to 95/5, particularly preferably 50/50 to 90/10.

Bags made of films and stretched films obtained as described above, and containers and lids made of cups, trays, tubes, bottles, etc., can be used for general foods, seasonings such as mayonnaise and dressing, miso, etc. It is useful as a variety of packaging material containers for fermented foods, oil and fat foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples shown in the table below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

[Example 1]
[Manufacture of EVOH resin composition]
As EVOH (A), EVOH (a1) [ethylene-vinyl alcohol copolymer with ethylene structural unit content 29 mol%, saponification degree 99.7 mol%, MFR 3.8 g/10 minutes (210°C, load 2160 g) EVOH (a1) pellets containing sodium acetate (b1) as acetic acid and/or its salt (B) were used. In addition, stearic acid (c1) is used as the aliphatic carboxylic acid (C), zinc stearate (d1) is used as the aliphatic carboxylic acid metal salt (D), and trans-cinnamic acid (e1) is used as the cinnamic acid and/or its salt (E). ), boric acid (f1) was used as boric acid and/or its salt (F).
In addition, the content of each component is as follows: sodium acetate (b1), EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), trans-cinnamic acid (e1). Using 432 ppm in terms of acetate ion with respect to the total of Using 2.4 ppm in terms of carboxylic acid ion with respect to the total content, zinc stearate (d1) was mixed with EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), trans- Using 50 ppm in terms of metal ions with respect to the total content of cinnamic acid (e1), trans-cinnamic acid (e1) was added to EVOH (a1), sodium acetate (b1), stearic acid (c1), and zinc stearate (d1). ), using 150 ppm in terms of cinnamic acid ion with respect to the total content of trans-cinnamic acid (e1), and using boric acid (f1) as EVOH (a1), sodium acetate (b1), stearic acid (c1), stearic acid 59.45 ppm in terms of boron was used based on the total content of zinc (d1), trans-cinnamic acid (e1), and boric acid (f1). The EVOH resin composition of the present invention was produced by dry blending EVOH (a1) pellets, stearic acid (c1), zinc stearate (d1), trans-cinnamic acid (e1), and boric acid (f1) all at once. .

[Manufacture of multilayer structure]
The EVOH resin composition prepared above and linear low density polyethylene (LLDPE) [“UF240” manufactured by Japan Polyethylene Co., Ltd., MFR 2.1 g/10 minutes (190 ° C. , load 2160 g)], adhesive resin (LyondellBasell "PLEXAR PX3236", MFR 2.0 g/10 minutes [190°C, load 2160 g]) was applied, and the LLDPE layer/adhesion was formed by multilayer coextrusion molding under the following conditions. A multilayer structure (film) having a three-type, five-layer structure consisting of an EVOH resin layer/EVOH resin composition layer/adhesive resin layer/LLDPE layer was obtained. The thickness (μm) of each layer of the multilayer structure was 37.5/5/15/5/37.5. The die temperature of all molding devices was set at 210°C.
(Multilayer coextrusion molding conditions)
・Middle layer extruder (EVOH resin composition): 40mmφ single screw extruder (barrel temperature: 210°C)
・Upper and lower layer extruder (LLDPE): 40mmφ single screw extruder (barrel temperature: 210℃)
・Middle and upper layer extruder (adhesive resin): 32mmφ single screw extruder (barrel temperature: 210℃)
・Die: 3 types 5 layer feed block type T die (Die temperature: 210℃)
・Take-up speed: 9.0m/min ・Roll temperature: 80℃

The EVOH resin composition obtained above was subjected to the following color stability evaluation test and extensional viscosity evaluation test, and the multilayer structure obtained above was subjected to the following impact strength evaluation test. , an adhesive strength evaluation test, and a light resistance evaluation test.

<Evaluation of color stability of EVOH resin composition>
5 g of the EVOH resin composition produced above was placed in a 30 mm diameter aluminum cup (manufactured by As One Corporation, Dispodinish PP-724) and allowed to stand at 210° C. for 2 hours in an air atmosphere, and then used as a sample for color tone evaluation. Color tone evaluation was performed based on the following apparatus and evaluation method.
・Equipment used: Visual analyzer IRISVA400 (manufactured by Alpha Mos Japan)
・Data analysis software: Alpha Soft V14.3
・Objective lens: 25mm (manufactured by Basler)
・Illumination mode: Up and down illumination ・Evaluation method: Set the sample for color tone evaluation on the tray in the chamber of the above visual analyzer, take a planar image of the entire sample for color tone evaluation with a CCD camera, and then use data analysis software. The color pattern of the sample was evaluated by image processing. The color tone stability of the EVOH resin composition was evaluated based on the lightness (L*) of the color (main color) that was present the most among the obtained color patterns. In addition, the color stability means that the higher the numerical value is, the more excellent the color tone stability is, and conversely, the lower the numerical value is, the poorer the color tone stability is. The results are shown in Table 1-2.

<Evaluation of elongational viscosity (Pa・s) of EVOH resin composition>
The elongational viscosity (Pa.s) at 210°C and 100S ^-1 of the EVOH resin composition produced above was calculated using the Cogswell equation [Polymer Engineering Science, Vol. 12, pp. 64-73] using a capillary rheometer. 1972)], that is, the evaluation was made by conducting measurements under the following conditions based on the following equations (5) to (7). The results are shown in Table 1-2.
(Cogswell style)
η _e = [9(n+1) ² P ₀ ² ]/[32η _s (dγ/dt) ² ]...Equation (5)
dε/dt=4σ _s (dγ/dt)/[3(n+1)P ₀ ]...Equation (6)
σ _s =k(dγ/dt) ⁿ ...Formula (7)
η _e : Elongational viscosity (Pa・s)
η _s : Shear viscosity (Pa・s)
dγ/dt: shear strain rate (s ^-1 )
dε/dt: Elongation strain rate (s ^-1 )
σ _s : Shear stress (Pa)
k, n: Constant P ₀ : Pressure loss (Pa)
(Elongational viscosity measurement conditions)
Measuring device: RHEOGRAPH 20 manufactured by Gottfert
Measurement temperature: 210℃
Preheating time: 10 minutes Long die: length 10mm, diameter 1mm, inlet angle 180°
Short die: length 0.2mm, diameter 1mm, inlet angle 180°

<Impact strength of multilayer structure>
The impact strength (kgf·cm) of the multilayer structure produced above was evaluated in an atmosphere of 23° C. and 50% RH using a YSS film impact tester (manufactured by Yasuda Seiki Seisakusho, Model 181). The measurements were performed 10 times in total, and the average value was evaluated as the impact strength of the multilayer structure. The inner diameter of the clamp was 60 mm, the radius of the impact ball was 12.7 mm, and the lifting angle of the pendulum was 90°. Note that the higher the value of the impact strength of the multilayer structure, the better the impact strength, and conversely, the lower the value, the worse the impact strength. The results are shown in Table 1-2.

<Adhesive strength of multilayer structure>
The adhesive strength (N/15 mm) between the EVOH resin composition layer and the adhesive resin layer in the multilayer structure produced above was evaluated by the following T-peel peel test. The measurement was performed 10 times in total, and the average value was evaluated as the adhesive strength of the multilayer structure. In addition, the adhesive strength of a multilayer structure means that the higher the numerical value is, the better the adhesive strength is, and conversely, the lower the numerical value is, the poorer the adhesive strength is. The results are shown in Table 1-2.
(T-peel peeling test conditions)
・Device: Autograph AGS-H (manufactured by Shimadzu Corporation)
・Load cell: 500N
・Test method: T-peel method (cut into T-shape and peeled off)
・Test piece size: width 15mm
・Test speed: 300mm/min

<Light resistance of multilayer structure>
The light resistance of the multilayer structure produced above was measured by measuring the transmittance (%) at a wavelength of 280 nm (ultraviolet region) using a spectrophotometer "UV2600" manufactured by Shimadzu Corporation. In addition, a reference multilayer structure was produced using the same procedure, and the transmittance (%) was measured in the same manner.

Thereafter, the ultraviolet absorption increase rate (Z) was calculated using the following formula (8), and the light resistance of the multilayer structure was evaluated using the following evaluation criteria. In addition, regarding the light resistance of the multilayer structure, the higher the value of the ultraviolet absorption increase rate (Z), the better the light resistance, and conversely, the lower the value, the worse the light resistance. The results are shown in Table 1-2.
A: Ultraviolet absorption increase rate (Z)≧2
B: 1.5≦ultraviolet absorption increase rate (Z)<2
C: Ultraviolet absorption increase rate (Z) <1.5

Ultraviolet absorption increase rate (Z) [(UV transmittance of reference film)/(UV transmittance of multilayer structure of Example 1)]...Equation (8)

[Example 2]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 0.7 ppm in terms of carboxylic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 3]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). Using 4.9 ppm in terms of carboxylic acid ion, zinc stearate (d1) contains EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 100 ppm was used in terms of metal ions based on the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 4]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). Using 9.7 ppm in terms of carboxylic acid ion, zinc stearate (d1) contains EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 200 ppm was used in terms of metal ions based on the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 5]
In Example 1, caprylic acid (c2) was substituted for stearic acid (c1) by EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), trans-cinnamic acid (e1). Using 6.9 ppm in terms of carboxylic acid ion with respect to the total content of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2) was used instead of zinc stearate (d1). , zinc caprylate (d2), and trans-cinnamic acid (e1), using 50 ppm in terms of metal ions, trans-cinnamic acid (e1), EVOH (a1), sodium acetate (b1), and caprylic acid. The EVOH resin composition and multilayer structure were prepared in the same manner except that 5 ppm was used in terms of cinnamic acid ion with respect to the total content of acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). Created. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 6]
In Example 5, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). On the other hand, an EVOH resin composition and a multilayer structure were produced in the same manner except that 20 ppm in terms of cinnamic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 7]
In Example 5, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). On the other hand, an EVOH resin composition and a multilayer structure were produced in the same manner except that 150 ppm in terms of cinnamic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 8]
In Example 5, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). On the other hand, an EVOH resin composition and a multilayer structure were produced in the same manner except that 1000 ppm in terms of cinnamic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 9]
In Example 5, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). Using 150 ppm in terms of cinnamic acid ion, boric acid (f1) was added to EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), trans-cinnamic acid (e1), and boric acid. An EVOH resin composition and a multilayer structure were produced in the same manner except that 300 ppm in terms of boron was used with respect to the total content of (f1). The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 10]
In Example 5, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). The content of caprylic acid (c2) was EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1) using 150 ppm in terms of cinnamic acid ion. Zinc caprylate (d2) was used as EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), trans-cinnamic acid. An EVOH resin composition and a multilayer structure were produced in the same manner except that 100 ppm in terms of metal ions was used with respect to the total content of (e1). The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 11]
In Example 10, sodium acetate (b1) was added to the total content of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). Using 100 ppm in terms of acetate ion, boric acid (f1) was converted into EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), trans-cinnamic acid (e1), boric acid (f1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 13.7 ppm in terms of boron was used with respect to the total content of . The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 12]
In Example 10, caprylic acid (c2) was added to the total content of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). Using 27.6 ppm in terms of carboxylic acid ion, zinc caprylate (e1) contains EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 200 ppm was used in terms of metal ions based on the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 13]
In Example 1, lauric acid (c3) was substituted for stearic acid (c1) by EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), trans-cinnamic acid (e1). Using 1.8 ppm in terms of carboxylic acid ion with respect to the total content of EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3) was used instead of zinc stearate (d1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm in terms of metal ions was used based on the total content of zinc laurate (d3) and trans-cinnamic acid (e1). The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 14]
In Example 13, lauric acid (c3) was added to the total content of EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). Using 3.6 ppm in terms of carboxylic acid ion, zinc laurate (d3) contains EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 100 ppm was used in terms of metal ions based on the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 15]
In Example 13, lauric acid (c3) was added to the total content of EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). Using 7.1 ppm in terms of carboxylic acid ion, zinc laurate (d3) contains EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 200 ppm was used in terms of metal ions based on the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 16]
In Example 1, behenic acid (c4) was substituted for stearic acid (c1) by EVOH (a1), sodium acetate (b1), behenic acid (c4), zinc behenate (d4), trans-cinnamic acid (e1). Using 2.9 ppm in terms of carboxylic acid ion with respect to the total content of EVOH (a1), sodium acetate (b1), and behenic acid (c4), zinc behenate (d4) was used instead of zinc stearate (d1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm in terms of metal ions was used based on the total content of zinc behenate (d4) and trans-cinnamic acid (e1). The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 17]
In Example 7, caprylic acid (c2) was added to the total content of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 269 ppm in terms of carboxylic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Example 18]
In Example 13, lauric acid (c3) was added to the total content of EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 355 ppm in terms of carboxylic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 1]
An EVOH resin composition and a multilayer structure were produced in the same manner as in Example 7 except that trans-cinnamic acid (e1) was not used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 2]
In Example 7, trans-cinnamic acid (e1) was added to the sum of the contents of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). On the other hand, an EVOH resin composition and a multilayer structure were produced in the same manner except that 5000 ppm in terms of cinnamic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 3]
An EVOH resin composition and a multilayer structure were produced in the same manner as in Example 7 except that caprylic acid (c2) and zinc caprylate (d2) were not used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 4]
An EVOH resin composition and a multilayer structure were produced in the same manner as in Example 7 except that sodium acetate (b1) and boric acid (f1) were not used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 5]
In Example 7, caprylic acid (c2) was added to the total content of EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). Using 82.8 ppm in terms of carboxylic acid ion, containing zinc caprylate (d2), EVOH (a1), sodium acetate (b1), caprylic acid (c2), zinc caprylate (d2), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 600 ppm in terms of metal ions was used with respect to the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 6]
In Example 13, lauric acid (c3) was added to the total content of EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). Using 21.4 ppm in terms of carboxylic acid ion, zinc laurate (d3) contains EVOH (a1), sodium acetate (b1), lauric acid (c3), zinc laurate (d3), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 600 ppm in terms of metal ions was used with respect to the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 7]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). Using 29.2 ppm in terms of carboxylic acid ion, zinc stearate (d1) contains EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 600 ppm in terms of metal ions was used with respect to the total amount. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 8]
In Example 1, stearic acid (c1) was converted into carboxylic acid ion based on the sum of the contents of EVOH (a1), sodium acetate (b1), stearic acid (c1), calcium stearate, and trans-cinnamic acid (e1). Calcium stearate was used at 1.9 ppm, and 50 ppm in terms of metal ions was used for the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), calcium stearate, and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that the following steps were taken. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 9]
In Example 1, stearic acid (c1) was converted to carboxylic acid ion based on the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), magnesium stearate, and trans-cinnamic acid (e1). Converted to 15.4 ppm, calcium stearate was used instead of zinc stearate (d1), content of EVOH (a1), sodium acetate (b1), stearic acid (c1), magnesium stearate, trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm in terms of metal ions was used with respect to the total sum of . The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 10]
In Example 1, stearic acid (c1) was converted to carboxylic acid ion based on the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), sodium stearate, and trans-cinnamic acid (e1). Converted to 3.3 ppm, using calcium stearate instead of zinc stearate (d1), content of EVOH (a1), sodium acetate (b1), stearic acid (c1), sodium stearate, trans-cinnamic acid (e1) An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm in terms of metal ions was used with respect to the total sum of . The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 11]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 483.6 ppm in terms of carboxylic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 12]
In Example 1, stearic acid (c1) was added to the total content of EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc stearate (d1), and trans-cinnamic acid (e1). An EVOH resin composition and a multilayer structure were produced in the same manner except that 0.4 ppm in terms of carboxylic acid ion was used. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 13]
In Example 1, zinc gluconate trihydrate was used instead of zinc stearate (d1) in EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc gluconate trihydrate, trans-cinnamonium An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm of acid (e1) was used in terms of metal ions with respect to the total content. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

[Comparative example 14]
In Example 1, zinc gluconate dihydrate was used instead of zinc stearate (d1), and EVOH (a1), sodium acetate (b1), stearic acid (c1), zinc gluconate dihydrate, trans-cinnamate An EVOH resin composition and a multilayer structure were produced in the same manner except that 50 ppm of acid (e1) was used in terms of metal ions with respect to the total content. The obtained EVOH resin composition and multilayer structure were evaluated in the same manner as in Example 1.

Comparative Example 1, which did not contain cinnamic acid and/or its salt (E), had poor light resistance.
Furthermore, Comparative Example 2, which did not satisfy the formula (1) specified in the present invention, had low impact strength, adhesive strength, and color stability.
In addition, in Comparative Example 3 which does not contain the aliphatic carboxylic acid metal salt (D), the impact strength is 14.50 (kgf cm), whereas it contains the aliphatic carboxylic acid metal salt (D) and acetic acid In Comparative Example 4, which does not contain and/or its salt (B), the impact strength was improved to 17.19 (kgf·cm). However, the adhesive strength decreased to 3.08 (N/15 mm).
Furthermore, in Comparative Examples 4 to 7, which did not satisfy the formula (2) specified in the present invention, the adhesive strength was low. Comparative Examples 11 and 12, which did not satisfy the formula (3) specified in the present invention, had low impact strength.
Furthermore, the impact strength was also low in Comparative Examples 8 to 10, in which the metal species of the aliphatic carboxylic acid metal salt (D) was not one selected from the elements belonging to the 4th period d block of the long periodic table. Ta.
In Comparative Examples 13 and 14, in which the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (D) did not have the same anion species, the impact strength and adhesive strength were low.

The EVOH resin compositions (Examples 1 to 18) having the characteristic structure of the present invention exhibited excellent impact strength and light resistance, but exhibited excellent adhesive strength without decreasing. Furthermore, the color stability was not reduced. Moreover, it was also excellent in light resistance.

A package was manufactured using the multilayer structure of each example obtained above. The resulting packages were all excellent in impact resistance and adhesive strength.

In the above embodiments, specific embodiments of the present invention have been shown, but the above embodiments are merely illustrative and should not be construed as limiting. Various modifications apparent to those skilled in the art are intended to be within the scope of the invention.

The EVOH resin composition of the present invention has excellent impact resistance and adhesive strength. Therefore, multilayer structures containing layers made of the EVOH resin composition can be used in general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oil and fat foods such as salad oil, beverages, cosmetics, and pharmaceuticals. It is useful as a raw material for various packaging materials such as containers.

Claims (11)

Ethylene-vinyl alcohol copolymer (A), acetic acid and/or its salt (B), aliphatic carboxylic acid other than acetic acid (C), aliphatic carboxylic acid that is a metal salt of the above aliphatic carboxylic acid (C) A resin composition containing a metal salt (D), cinnamic acid and/or its salt (E), wherein the metal species of the aliphatic carboxylic acid metal salt (D) is in period d of the long periodic table. At least one element selected from the elements belonging to the block, the acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), the cinnamic acid and/or An ethylene-vinyl alcohol copolymer resin composition characterized in that various contents of the salt (E) satisfy the following formulas (1) to (3) on a weight basis.
[Formula] 0.015≦((D) content in terms of metal ions/(E) content in terms of cinnamate ions)≦50...(1)
[Formula] 0.001≦((D) metal ion equivalent content/(B) acetate ion equivalent content)≦1.30...(2)
[Formula] 0.11≦((D) metal ion equivalent content/(C) carboxylic acid ion equivalent content)≦100...(3) The ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the metal species of the aliphatic carboxylic acid metal salt (D) is zinc. The content of the cinnamic acid and/or its salt (E) in terms of cinnamic acid ion is the content of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), the aliphatic carbon 1 or 2, wherein the content is 1 to 1000 ppm based on the total content of the acid (C), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E). 2. The ethylene-vinyl alcohol copolymer resin composition according to 2. The content of the aliphatic carboxylic acid metal salt (D) in terms of metal ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), and the aliphatic carboxylic acid (D). C), the content of the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E) is 1 to 500 ppm based on the total content thereof. The ethylene-vinyl alcohol copolymer resin composition according to any one of the items. The content of the aliphatic carboxylic acid (C) in terms of carboxylic acid ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), and the aliphatic carboxylic acid (C). ), the aliphatic carboxylic acid metal salt (D), and the cinnamic acid and/or its salt (E) in a total amount of 0.001 to 450 ppm. The ethylene-vinyl alcohol copolymer resin composition according to any one of the above. The content of the acetic acid and/or its salt (B) in terms of acetate ion is the same as that of the ethylene-vinyl alcohol copolymer (A), the acetic acid and/or its salt (B), and the aliphatic carboxylic acid ( C), the content of the aliphatic carboxylic acid metal salt (D) and the cinnamic acid and/or its salt (E) is 10 to 2000 ppm, based on the total content of the metal salt (D) and the cinnamic acid and/or its salt (E), The ethylene-vinyl alcohol copolymer resin composition according to any one of the items. Content ratio of the above-mentioned cinnamic acid and/or its salt (E) in terms of cinnamic acid ion to the content of the above-mentioned acetic acid and/or its salt (B) in terms of cinnamic acid ion (in terms of cinnamic acid ion of (E)) The ethylene-vinyl alcohol based copolymer according to any one of claims 1 to 6, wherein the content/(B) content in terms of acetate ion is from 0.0001 to 10,000 on a weight basis. Polymer resin composition. 8. The ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 7, wherein the elongational viscosity at 210° C. and 100 S ^-1 satisfies the following formula (4). The ethylene-vinyl alcohol copolymer resin composition described above.
[Formula] 500≦Elongational viscosity [Pa・s]≦48000...(4) Furthermore, in the above ethylene-vinyl alcohol copolymer resin composition containing boric acid and/or its salt (F), the boric acid and/or its salt (F) is Coalescence (A), the acetic acid and/or its salt (B), the aliphatic carboxylic acid (C), the aliphatic carboxylic acid metal salt (D), the cinnamic acid and/or its salt (E), the boron Ethylene-vinyl according to any one of claims 1 to 8, characterized in that it contains 0.001 to 500 ppm in terms of boron with respect to the total content of the acid and/or its salt (F). Alcohol-based copolymer resin composition. A multilayer structure comprising a layer made of the ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 9. A packaging body comprising the multilayer structure according to claim 10.