Resin composition, molding material, multilayer structure, molded body, food package, and methods for producing resin composition and multilayer structure

Abstract

Provided is a resin composition having excellent thermal stability.　The resin composition comprises an ethylene / vinyl alcohol copolymer (A) and nickel element (B). At least some of the ethylene / vinyl alcohol copolymer (A) is derived from biomass, and the proportion of the nickel element (B) is 0.0001 ppm or higher but less than 1.00 ppm with respect to the whole resin composition.

Description

Resin composition, molding material, multilayer structure, molded article, food packaging, method for manufacturing resin composition and multilayer structure

[0001] The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer, a molding material, a multilayer structure, a molded article, a food packaging article, a resin composition, and a method for producing a multilayer structure.

[0002] Ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH resin") has excellent transparency, gas barrier properties such as oxygen, fragrance retention, solvent resistance, oil resistance, and mechanical strength, and is molded into films, sheets, bottles, etc., and is widely used as a packaging material for various products such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials.

[0003] Furthermore, various improvements have been made to enhance the performance of EVOH resin. For example, Patent Document 1 discloses a resin composition containing an iron compound in EVOH resin to impart good ultraviolet absorption properties. Patent Document 2 also discloses a resin composition containing a titanium compound in EVOH resin to suppress discoloration of EVOH resin during melt molding.

[0004] Furthermore, in recent years, with the aim of creating a circular economy, there has been a growing demand for bioplastics made from carbon-neutral biomass-derived raw materials. Therefore, biomass-derived resins that are comparable in performance to fossil fuel-derived resins are being investigated by combining biomass-derived raw materials with fossil fuel-derived raw materials.

[0005] For example, Patent Document 3 discloses a gas barrier resin composition that uses biomass-derived raw materials while possessing gas barrier properties comparable to those of fossil fuel-derived resins, as well as sufficient long-run performance. This composition is a blend of biomass-derived EVOH resin and petroleum-derived EVOH resin.

[0006] International Publication No. 2017 / 115847, Japanese Patent Publication No. 2023-152988, International Publication No. 2022 / 004701

[0007] According to the inventors' investigations, the technologies disclosed in the above-mentioned Patent Documents 1 to 3 have some effect on thermal stability, but it was found that the thermal stability is still insufficient.

[0008] Therefore, against this background, the present invention provides a resin composition with excellent thermal stability.

[0009] In view of these circumstances, the present inventors conducted extensive research and found that by incorporating a specific trace amount of nickel element into an EVOH resin that is at least partially derived from biomass, a resin composition with excellent thermal stability can be obtained.

[0010] In other words, the present invention provides the following [1] to

[21] . [1] A resin composition containing an ethylene-vinyl alcohol copolymer (A) and an element nickel (B), wherein at least a portion of the ethylene-vinyl alcohol copolymer (A) is derived from biomass, and the content ratio of the element nickel (B) is 0.0001 ppm or more and less than 1.00 ppm with respect to the whole resin composition. [2] The ethylene-vinyl alcohol copolymer (A) is １４ Including C, and the above １４[1] The resin composition according to [1], wherein the content of C is 10 ppm or more. [3] The resin composition according to [1] or [2], wherein the biobase of the ethylene-vinyl alcohol copolymer (A) is 0.0001% or more and 100% or less. [4] The resin composition according to any one of [1] to [3], wherein the content of ethylene structural units in the ethylene-vinyl alcohol copolymer (A) is 20 to 60 mol%. [5] The resin composition according to any one of [1] to [4], wherein the resin composition contains at least one selected from the group consisting of alkali metal elements, alkaline earth metal elements, boron elements, and lubricants. [6] The resin composition according to [5], wherein the ratio of the content of nickel element (B) to the content of alkali metal elements in the resin composition [content of alkali metal elements / content of nickel element (B)] is 200 to 600,000. [7] The resin composition according to [5], wherein the ratio of the content of nickel element to alkaline earth metal element in the resin composition [content of alkaline earth metal element / content of nickel element (B)] is 100 to 300,000. [8] The resin composition according to [5], wherein the ratio of the content of nickel element (B) to boron element in the resin composition [content of boron element / content of nickel element (B)] is 1,000 to 600,000. [9] The resin composition according to [5], wherein the ratio of the content of nickel element (B) to lubricant in the resin composition [content of lubricant / content of nickel element (B)] is 200 to 600,000.

[10] The resin composition according to any one of [1] to [4], wherein the resin composition contains a polyamide resin, and the content of nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm of the entire resin composition.

[11] The resin composition according to any one of [1] to [4], wherein the ethylene-vinyl alcohol copolymer (A) comprises an ethylene-vinyl alcohol copolymer (A-1) and an ethylene-vinyl alcohol copolymer (A-2) having different ethylene structural unit content ratios, and the difference in ethylene structural unit content ratios between the ethylene-vinyl alcohol copolymer (A-1) and the ethylene-vinyl alcohol copolymer (A-2) is 4 mol% or more, and the content ratio of the nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm with respect to the entire resin composition.

[12] The resin composition according to

[11] , comprising at least an ethylene-vinyl alcohol copolymer (A-1) having an ethylene structural unit content ratio of 20 to 34 mol%, and an ethylene-vinyl alcohol copolymer (A-2) having an ethylene structural unit content ratio of 35 to 60 mol%.

[13] The resin composition according to

[11] or

[12] , wherein the content of nickel element (B) is 0.0001 ppm or more and less than 0.30 ppm with respect to the entire resin composition.

[14] The resin composition according to

[12] or

[13] , wherein the mass ratio (ethylene-vinyl alcohol copolymer (A-1) / ethylene-vinyl alcohol copolymer (A-2)) of ethylene-vinyl alcohol copolymer (A-1) having a content of ethylene structural units of 20 to 34 mol% to ethylene-vinyl alcohol copolymer (A-2) having a content of ethylene structural units of 35 to 60 mol% is 95 / 5 to 30 / 70.

[15] A molding material comprising the resin composition according to any one of [1] to

[14] .

[16] The molding material according to

[15] , wherein the molding material is in pellet form.

[17] A multilayer structure having a layer comprising the resin composition according to any one of [1] to

[14] .

[18] A molded article comprising the multilayer structure according to

[17] .

[19] A food packaging comprising the multilayer structure described in

[17] .

[20] A method for producing the resin composition described in any one of [1] to

[14] , comprising the step of melting and mixing the resin composition raw materials containing the ethylene-vinyl alcohol copolymer (A) and nickel element (B).

[21] A method for producing the multilayer structure described in

[17] , comprising the step of melt-molding a layer containing the resin composition.

[0011] The resin composition of the present invention exhibits excellent thermal stability. Furthermore, molding materials, molded articles, food packaging, and multilayer structures having layers containing the resin composition of the present invention also exhibit excellent thermal stability.

[0012] The present invention will be described below based on examples of embodiments for carrying out the present invention. However, the present invention is not limited to the embodiments described below.

[0013] In this specification, "x and / or y (where x and y are any combination)" means at least one of x and y, and can mean x only, y only, or x and y. When expressed as "X to Y" (where X and Y are any numbers), unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." When expressed as "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number), it also includes the meaning of "preferably greater than X" or "preferably less than Y." In this specification, for numerical ranges described in stages, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range can be replaced with the values ​​shown in the examples. In this specification, a preferred combination of embodiments is a more preferred embodiment. In this specification, "layer" includes not only thick layers but also relatively thin layers such as "film," "tape," and "sheet." When describing measurement methods, etc., based on standards in this specification, unless otherwise specified, the standards shall be those in effect as of the filing date of this application (or the priority date, if applicable). If the standard has been abolished by that date, the standards in effect as of the date of abolition shall be used.

[0014] A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition") contains at least a portion of biomass-derived EVOH resin (A) and a trace amount of nickel element (B). The resin composition has EVOH resin (A) as its base resin, and the content of EVOH resin (A) in the resin composition is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0015] Furthermore, it is preferable that the resin composition further contains at least one selected from the group consisting of alkali metal elements, alkaline earth metal elements, boron elements, lubricants, and polyamide resins. In addition, it is also preferable that the EVOH resin contains two or more EVOH resins with different ethylene structural unit content ratios.

[0016] Hereinafter, a configuration containing EVOH resin (A) and nickel element (B) will be referred to as "the first embodiment," and the cases in which alkali metal elements are further added to the first embodiment will be referred to as "the second embodiment," the cases in which alkaline earth metal elements are added as "the third embodiment," the cases in which boron elements are added as "the fourth embodiment," the cases in which a lubricant is added as "the fifth embodiment," the cases in which polyamide resin is added as "the sixth embodiment," and the cases in which two or more types of EVOH resins with different ethylene structural unit content ratios are added as "the seventh embodiment," and these will be described in order.

[0017] <<First Embodiment>> The first embodiment includes the following embodiments <I-1> to <I-11>. <I-1> A resin composition containing EVOH resin (A) and nickel element (B), wherein at least a portion of the EVOH resin (A) is biomass-derived, and the content ratio of the nickel element (B) is 0.0001 ppm or more and less than 1.0 ppm with respect to the whole resin composition. <I-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <I-1>, wherein the content of C is 10 ppm or more. <I-3> A resin composition according to <I-1> or <I-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <I-4> A resin composition according to any one of <I-1> to <I-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <I-5> A molding material comprising the resin composition according to any one of <I-1> to <I-4>. <I-6> A molding material according to <I-5>, wherein the molding material is in pellet form. <I-7> A multilayer structure having a layer comprising the resin composition according to any one of <I-1> to <I-4>. <I-8> A molded article comprising the multilayer structure according to <I-7>. <I-9> A food packaging article comprising the multilayer structure according to <I-7>. <I-10> A method for producing a resin composition according to any one of <I-1> to <I-4>, comprising the step of melting and mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <I-11> A method for producing a multilayer structure according to <I-7>, comprising the step of melt-molding a layer containing the resin composition.

[0018] The present invention will be described below based on an example of an embodiment for carrying out the first aspect.

[0019] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the Resin Composition (1)") contains at least a portion of biomass-derived EVOH resin (A) and a trace amount of nickel element (B). The base resin of the Resin Composition (1) is EVOH resin (A), and the content ratio of EVOH resin (A) in the Resin Composition (1) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0020] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (1) is derived from biomass in at least a portion of its composition. More specifically, it refers to an EVOH resin in which at least a portion of its ethylene structural units, vinyl alcohol structural units, and vinyl ester structural units are derived from biomass. In other words, EVOH resin (A) is a water-insoluble thermoplastic resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and vinyl ester, in which at least a portion is derived from biomass.

[0021] The biomass origin of the ethylene and / or vinyl ester used as raw materials can be confirmed by measuring the bio-basedness. Bio-basedness is an index representing the proportion of biomass-derived raw materials and can be measured according to the method described in ASTM D6866-18. In other words, if the bio-basedness of EVOH resin is generally greater than 0% and 100% or less, it can be said that the ethylene and / or vinyl ester used as raw materials contains biomass-derived material.

[0022] "Biomass" refers to organic resources derived from plants and animals, excluding those derived from fossil fuels (fossil resources). From a cost and environmental perspective, it is preferable for biomass to be organic resources derived from plants, i.e., plant-based raw materials.

[0023] Biomass-derived ethylene can be produced, for example, by purifying bioethanol from biomass raw materials and carrying out a dehydration reaction. Biomass-derived vinyl esters can be produced, for example, by a common industrial method of reacting biomass-derived ethylene with acetic acid and oxygen molecules using a palladium catalyst.

[0024] Examples of biomass raw materials include waste-based, unused-based, and resource crop-based materials, for example: cellulosic crops (pulp, kenaf, wheat straw, rice straw, waste paper, papermaking residues, etc.), wood, charcoal, compost, natural rubber, cotton, sugarcane, okara, oils and fats (rapeseed oil, cottonseed oil, soybean oil, coconut oil, castor oil, etc.), carbohydrate crops (corn, tubers, wheat, rice, rice husk, rice bran, stale rice, cassava, sago palm, etc.), bagasse, buckwheat, soybean, essential oils (pine root oil, orange oil, eucalyptus oil, etc.), pulp black liquor, vegetable oil residue, and the like. These may be used alone or in combination of two or more thereof.

[0025] As a method for producing bioethanol, for example, there may be mentioned a method in which a biomass raw material is optionally pretreated (pressurized hot water treatment, acid treatment, alkali treatment, saccharification treatment using a saccharifying enzyme), then subjected to yeast fermentation to produce bioethanol, and then bioethanol is purified through a distillation step and a dehydration step. When saccharification treatment is performed during bioethanol production, separate hydrolysis and fermentation, in which saccharification and fermentation are performed stepwise, may be used, or simultaneous saccharification and fermentation, in which saccharification and fermentation are performed simultaneously, may be used; however, from the viewpoint of production efficiency, producing bioethanol by simultaneous saccharification and fermentation is preferred.

[0026] The proportion of biomass-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is usually 0.001 to 100 mol%, preferably 5 to 98 mol%, more preferably 15 to 97 mol%, even more preferably 25 to 96 mol%, and particularly preferably 35 to 95 mol%, although the total ethylene structural units may be biomass-derived. The proportion of fossil fuel-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is usually 99.999 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, even more preferably 75 mol% or less, and particularly preferably 65 mol% or less. The lower limit is 0 mol%, for example, 0 to 99.999 mol%. Fossil fuel-derived ethylene structural units may not be included in the total ethylene structural units. When the proportion of biomass-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is high, the bio-based nature of the composition increases, and there is a tendency to reduce the environmental burden. Furthermore, if the EVOH resin (A) contains biomass-derived vinyl ester structural units and / or vinyl alcohol structural units, the proportion of biomass-derived ethylene structural units in the total ethylene structural units may be 0.

[0027] Examples of biomass-derived vinyl esters include vinyl esters produced using biomass-derived ethylene. Specifically, examples include vinyl acetate, in which the carbon in the vinyl group portion is derived from biomass.

[0028] The proportion of biomass-derived vinyl alcohol structural units among all vinyl alcohol structural units (vinyl ester structural units) constituting the EVOH resin (A) is usually 0.001 to 100 mol%, preferably 5 to 98 mol%, more preferably 15 to 97 mol%, still more preferably 25 to 96 mol%, and particularly preferably 35 to 95 mol%. The proportion of fossil fuel-derived vinyl alcohol structural units among all vinyl alcohol structural units constituting the EVOH resin (A) is usually 99.999 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, still more preferably 75 mol% or less, and particularly preferably 65 mol% or less. The lower limit is 0 mol%, for example, 0 to 99.999 mol%. The total vinyl alcohol structural units do not necessarily have to contain fossil fuel-derived vinyl alcohol structural units. When the proportion of biomass-derived vinyl alcohol structural units among all vinyl alcohol structural units constituting the EVOH resin increases, the biobased content of the present resin composition (1) increases, which tends to reduce environmental load.

[0029] When the EVOH resin (A) contains biomass-derived ethylene structural units, the ratio of the total of biomass-derived vinyl ester structural units and biomass-derived vinyl alcohol structural units to the total of vinyl ester structural units and vinyl alcohol structural units may be 0.

[0030] That the EVOH resin (A) is derived from biomass can be confirmed by confirming the presence of "carbon-14" (hereinafter referred to as " １４ C") in the present resin composition (1), thereby confirming that it is biomass-derived. " １４ C" is present in biomass-derived EVOH resins, and its presence cannot be confirmed in petroleum-derived EVOH resins, while its presence can be confirmed in EVOH resins that are biomass-derived.

[0031] The EVOH resin (A) used in the present resin composition (1) is such that the EVOH resin (A) １４ contains C, and １４It is preferable that the content of C is 10 ppm or more. More specifically, it is preferable that at least a part of the ethylene structural unit, vinyl alcohol structural unit, and vinyl ester structural unit of the EVOH resin (A) contains １４ C in the EVOH resin. In the present specification, in accordance with the method described in ASTM D6866-18, concentration measurement of radiocarbon ( １４ C) is performed by accelerator mass spectrometry (AMS), and １４ the content of C can be determined.

[0032] １４ The content of C is usually 10 ppm or more, preferably 10 ppm or more and 500000 ppm or less, more preferably 100 ppm or more and 100000 ppm or less, still more preferably 500 ppm or more and 50000 ppm or less, particularly preferably 600 ppm or more and 40000 ppm or less, and most preferably 700 ppm or more and less than 30000 ppm. １４ When the content of C is not less than the above lower limit, the thermal stability becomes good; on the other hand, when the content of C is not more than the above upper limit, there tends to be an excellent long-run processability.

[0033] It should be noted that EVOH resins are considered to have a problem with thermal stability, and in particular, thermal decomposition is speculated to be mainly caused by polyene structures formed in the main chain of the EVOH resin through a dehydration reaction starting from hydroxyl groups. In the present resin composition (1), by using a biomass-derived EVOH resin, １４ due to the primary isotope effect of C (increase in binding energy), it is speculated that the thermal decomposition rate of the EVOH resin itself decreases, and the thermal stability is improved.

[0034] The content of ethylene structural units in the EVOH resin (A) is preferably 20 to 60 mol%, more preferably 25 to 50 mol%, and particularly preferably 25 to 35 mol%. When the content is not less than the above lower limit, the gas barrier property under high humidity and melt moldability tend to be excellent; conversely, when the content is not more than the above upper limit, the gas barrier property tends to be excellent. In the present specification, the content of ethylene structural units in the EVOH resin (A) is usually １ measured by 1H-NMR measurement. For example,１ 1H-NMR measurement was used, with DMSO-d as the measurement solvent. ６ A measurement method is used that employs a device and sets the measurement temperature to 50°C.

[0035] The degree of saponification of the EVOH resin (A) is usually 90 to 100 mol%, preferably 95 to 100 mol%, and more preferably 99 to 100 mol%. When the degree of saponification is above the lower limit, it tends to exhibit excellent gas barrier properties, thermal stability, moisture resistance, etc. The degree of saponification of such EVOH resin (A) is usually, １ It is measured by 1H-NMR measurement. For example, １ A measurement method is used that employs 1H-NMR measurement, using DMSO-d6 as the measurement solvent and a measurement temperature of 50°C.

[0036] The melt flow rate (MFR) (2160 g load at 210°C) of the EVOH resin (A) is typically 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and more preferably 3 to 35 g / 10 min. When the MFR is below the upper limit, the film tends to be stable, and when it is above the lower limit, it tends to have an appropriate viscosity and is suitable for melt extrusion. The MFR is an indicator of the degree of polymerization of the EVOH resin (A) and can be adjusted by the amount of polymerization initiator and solvent used when copolymerizing ethylene and vinyl ester.

[0037] The bio-based content of the EVOH resin (A) is preferably 0.001% to 100%, more preferably 0.01% to 10%, even more preferably 0.05% to 5%, and particularly preferably 0.07% to less than 3%.

[0038] Furthermore, the EVOH resin (A) may further contain structural units derived from the following comonomers, to the extent that they do not impede the effects of the present invention (for example, 10 mol% or less of the EVOH resin (A)).Examples of the comonomers include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 3-buten-1,2-diol, 4-penten-1-ol, and 5-hexen-1,2-diol, and derivatives thereof such as esters and acylated products; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibuty Hydroxyalkylvinylidene diacetates such as lyloxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydride) phthalic acid, (anhydride) maleic acid, (anhydride) itaconic acid, or their salts, or mono or dialkyl esters with 1 to 18 carbon atoms in the alkyl group; acrylamide, N-alkylacrylamide with 1 to 18 carbon atoms in the alkyl group, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid, or their salts, acrylamidopropyldimethylamine, or its salts, or its quaternary salts Acrylamides such as: methacrylamide, N-alkylmethacrylamide with 1 to 18 C1 of the alkyl group, N,N-dimethylmethacrylamide, 2-methacrylamidepropanesulfonic acid or its salts, methacrylamidopropyldimethylamine or its salts or its quaternary salts, etc.; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc.; vinyl cyanides such as acrylonitrile, methacrylnitrile, etc.; alkyl vinyl ethers with 1 to 18 C1 of the alkyl group, hydro Examples include vinyl ethers such as xyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl halogenated compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halogenated compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These can be used individually or in combination of two or more types.

[0039] Among these, hydroxyl group-containing α-olefins are preferred, and 3-butene-1,2-diol, 5-hexene-1,2-diol, and 2-methylene-1,3-diol are particularly preferred. When the hydroxyl group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in its side chains. Such EVOH resins having primary hydroxyl groups in their side chains, and especially EVOH resins having a 1,2-diol structure in their side chains, are preferred because they maintain gas barrier properties while exhibiting good secondary moldability.

[0040] When the EVOH resin (A) has a primary hydroxyl group in its side chain, the content of structural units derived from the monomer having the primary hydroxyl group is typically 0.1 to 20 mol%, preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol% of the EVOH resin.

[0041] Furthermore, as the EVOH resin (A), a "post-modified" EVOH resin such as esterification, urethaneization, acetalization, cyanoethylation, or oxyalkyleneization can also be used.

[0042] When using the post-modified EVOH resin described above, the modification rate is usually 10 mol% or less, preferably 4 mol% or less. The lower limit is usually 0.01 mol% or more, preferably 0.1 mol% or more, for example, 0.01 to 10 mol%, preferably 0.1 to 4 mol%. When the modification rate of the EVOH resin is within the above range, it tends to have excellent thermal degradation prevention and long-run performance.

[0043] Furthermore, the EVOH resin (A) may be a mixture of EVOH resins with different ethylene structural unit content, degree of saponification, degree of polymerization, copolymer components, etc.

[0044] As described above, the EVOH resin (A) used in this resin composition (1) is obtained by saponifying a copolymer of ethylene and vinyl ester, which is at least partially derived from biomass. Any known polymerization method can be used for copolymerization, such as solution polymerization, suspension polymerization, emulsion polymerization, etc.

[0045] Typical polymerization solvents include lower alcohols such as methanol, ethanol, propanol, and butanol, as well as ketones such as acetone and methyl ethyl ketone. These can be used individually or in combination of two or more. Industrially, methanol is preferred as the polymerization solvent.

[0046] The amount of polymerization solvent used should be appropriately selected according to the degree of polymerization of the target copolymer, taking into account the chain transfer constant of the polymerization solvent. For example, when methanol is the polymerization solvent, S (polymerization solvent) / M (monomer) is selected from a range of approximately 0.01 to 10 (mass ratio), preferably 0.05 to 7 (mass ratio).

[0047] Examples of polymerization catalysts include known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauryl peroxide, as well as low-temperature active radical polymerization catalysts. Examples of low-temperature active radical polymerization catalysts include peroxyesters such as t-butyl peroxyneodecanoate, t-butyl peroxypivalate, α,α'-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, and t-hexyl peroxypivalate, as well as di-n-propyl peroxydicarbonate, di-iso-propyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and bis(4-t Examples include peroxydicarbonates such as (-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, dimethoxybutyl peroxydicarbonate, and di(3-methyl-3-methoxybutyl peroxy)dicarbonate; organic peroxides such as diacyl peroxides such as 3,3,5-trimethylhexanoyl peroxide, diisobutyryl peroxide, and lauroyl peroxide; and azo compounds such as 2,2'-azobis-(2,4-dimethylvaleronitrile) and 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile). Such low-temperature active radical polymerization catalysts refer to organic compounds with a half-life of 10 to 300 minutes at 60°C. These polymerization catalysts may be used individually or in combination of two or more.

[0048] The amount of polymerization catalyst used varies depending on the type of catalyst and cannot be determined in general terms, but it can be arbitrarily selected according to the polymerization rate. For example, when using azobisisobutyronitrile or acetyl peroxide, 0.001 to 0.2 parts by mass, and more preferably 0.005 to 0.1 parts by mass, is preferred per 100 parts by mass of vinyl ester monomer.

[0049] The method for introducing ethylene into a copolymer is to perform conventional ethylene pressure polymerization. The amount of ethylene introduced can be controlled by the ethylene pressure, and although it cannot be said definitively as it depends on the content ratio of the target ethylene structural units, it is usually selected from the range of 2.0 to 8.0 MPa.

[0050] The reaction temperature for copolymerization cannot be generalized as it depends on the polymerization solvent and pressure used, but it is usually carried out below the boiling point of the polymerization solvent, and is generally preferably 40 to 80°C, and particularly preferably 55 to 80°C. When the temperature is above the lower limit, polymerization proceeds appropriately, so it is not necessary to set a large amount of catalyst to shorten the polymerization time, and conversely, when the temperature is below the upper limit, polymerization control tends to be excellent.

[0051] Furthermore, in the case of batch polymerization, the polymerization time is usually preferably 4 to 10 hours, and more preferably 6 to 9 hours. If the polymerization time is above the lower limit, there is a tendency to not need to raise the polymerization temperature or set a large amount of catalyst, and conversely, if it is below the upper limit, productivity tends to be excellent. In the case of continuous polymerization, the average residence time in the polymerization tank is usually preferably 2 to 8 hours, and more preferably 2 to 6 hours. If the residence time is above the lower limit, there is a tendency to not need to raise the polymerization temperature or set a large amount of catalyst, and conversely, if the polymerization time is below the upper limit, productivity tends to be excellent.

[0052] The polymerization rate is set as high as possible within the range where polymerization control is possible from a productivity standpoint, preferably 30 to 60%. If the polymerization rate is above the lower limit, productivity is excellent and there is a tendency to prevent a large amount of unpolymerized vinyl ester monomer from remaining, while conversely, if it is below the upper limit, there is a tendency to be excellent polymerization control.

[0053] The ethylene-vinyl ester copolymer obtained in this way can be saponified to obtain EVOH resin (A). Saponification is carried out using a saponification catalyst while the ethylene-vinyl ester copolymer obtained above is dissolved in alcohol or aqueous alcohol.

[0054] Examples of the aforementioned alcohols include lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, and propanol. These may be used individually or in combination of two or more. Methanol is particularly preferred.

[0055] The concentration of the ethylene-vinyl ester copolymer in the alcohol is appropriately selected depending on the viscosity, and is usually 5 to 60% by mass.

[0056] Examples of the saponification catalyst include alkali metal hydroxides and alkoxides such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, and potassium ethylate; and acid catalysts such as sulfuric acid, hydrochloric acid, nitric acid, metasulfonic acid, zeolite, and cation exchange resin. These may be used individually or in combination of two or more. Among these, alkali metal hydroxides and alkoxides are preferred.

[0057] The temperature at which saponification is carried out is not limited, but 20 to 140°C is preferred, and the saponification time is preferably 1 to 5 hours.

[0058] The EVOH resin (A) produced in this manner may be at least partially derived from biomass, preferably the ethylene structural units and / or vinyl alcohol structural units are biomass-derived, and more preferably, from the viewpoint of availability, the vinyl alcohol structural units are biomass-derived. Such EVOH resin (A) mainly consists of ethylene structural units and vinyl alcohol structural units, and optionally contains a small amount of vinyl ester structural units that remain unsaponified. When other comonomers are copolymerized, structural units derived from those comonomers are further included.

[0059] Furthermore, the EVOH resin (A) produced by the above manufacturing method is contained in an alcohol-based solvent, and the EVOH resin content in the EVOH resin solution is preferably about 10 to 50% by mass from the viewpoint of producing the EVOH resin pellets described below.

[0060] The EVOH resin (A) used in this resin composition (1) may be the alcohol solvent of the EVOH resin produced by the above manufacturing method, but it is preferable that it be in pellet form. The shape and size of the pellets are preferably the same as those of the composition described later.

[0061] Furthermore, the prepared pellets are preferably washed by methods such as immersion in an aqueous solution of an acid and / or its salts. Examples of such chemicals include formic acid, acetic acid, adipic acid, phosphoric acid, boric acid, or their salts, with acetic acid being preferred. It is also preferable to wash them with water afterward.

[0062] Next, the chemically treated and washed pellets can be dried as appropriate, and it is preferable to dry them using a fluidized hot air dryer or a static hot air dryer. In this way, pellets of EVOH resin (A) can be produced.

[0063] [Nickel Element (B)] This resin composition (1) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm relative to the total amount of this resin composition (1), preferably 0.0001 ppm or more and 0.80 ppm or less, and more preferably 0.0005 ppm or more and 0.50 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of this resin composition (1) is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0064] The content ratio of nickel element (B) in the resin composition (1) can be determined, for example, by heating and ashing the resin composition and treating it with hydrochloric acid or the like to obtain a solution, adding pure water to the solution to obtain a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0065] The nickel element (B) used in this resin composition (1) can be included in the resin composition as a nickel compound containing it. Examples of nickel compounds include inorganic nickel compounds and organic nickel compounds. These can be used individually or in combination of two or more. Among these, inorganic nickel compounds are preferred.

[0066] Examples of the inorganic nickel compound include nickel oxide, nickel hydroxide, and inorganic nickel salts. Examples of the nickel oxide include nickel(II) oxide, nickel(III) oxide, nickel(IV) oxide, and nickel dioxide. Examples of the nickel hydroxide include nickel(I) hydroxide and nickel(II) hydroxide. Examples of the inorganic nickel salt include nickel(II) chloride, nickel(II) phosphate, nickel(II) sulfate, and nickel nitrate. Among these, nickel oxide is preferred, and nickel(II) oxide is more preferred, in that the effects of the invention are easily obtained.

[0067] Examples of the aforementioned organic nickel compounds include nickel carboxylate salts such as nickel(II) acetate, nickel(II) butyrate, and nickel(II) stearate.

[0068] Furthermore, the molecular weight of the nickel compound is typically 50 to 10,000, preferably 60 to 1,000, and more preferably 70 to 800, from the viewpoint of dispersibility and productivity in the resin composition (1). It should be noted that, from the viewpoint of economy and dispersibility, it is preferable to exclude layered inorganic compounds such as montmorillonite and double salts such as hydrotalcite from the nickel compound used in this embodiment.

[0069] The nickel compound can be in any form, such as solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, or emulsion (aqueous dispersion). Among these, powder form is preferred because it is easy to handle.

[0070] It is generally known that EVOH resins undergo a color change after heating. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, leading to the formation of polyene structures in the main chain of the EVOH resin.

[0071] In contrast, this resin composition (1) suppresses discoloration due to thermal degradation of the EVOH resin by containing a specific trace amount of nickel element (B). Normally, when nickel elements are included in a resin composition, it is thought that the resin composition will become discolored due to nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel elements.

[0072] However, contrary to this common technical knowledge, the present invention has found that when a specific trace amount of nickel element (B) is used, a resin composition (1) in which discoloration due to thermal degradation is suppressed can be obtained.

[0073] In other words, nickel is stable as a divalent ion and, even in trace amounts, is presumed to stabilize the EVOH resin by coordinating with the double bonds in the main chain and forming chelates, thereby suppressing the formation of polyene structures. On the other hand, it is thought that keeping the amount of nickel below the upper limit prevents thermal decomposition of the EVOH resin and subsequent discoloration. Furthermore, because nickel has a high ionization energy among metals, it is difficult for it to detach after coordinating with the double bonds in the main chain of the EVOH resin, and it is presumed that it can maintain a stable state for a relatively long time, thus exhibiting an effect when used in combination.

[0074] [Other Thermoplastic Resins] The resin composition (1) may contain thermoplastic resins other than EVOH resin in a range that does not impair the effects of the present invention (for example, usually 30% by mass or less of the resin composition, preferably 20% by mass or less, more preferably 10% by mass or less, with the lower limit usually being 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used alone or in combination of two or more.

[0075] [Other Compounding Agents] The resin composition (1) may also contain compounding agents (excluding nickel compounds) that are generally used in EVOH resins, within a range that does not impede the effects of the present invention (for example, usually 30% by mass or less of the resin composition (1), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of such compounding agents include titanium compounds, iron compounds, inorganic double salts (e.g., hydrotalcite), plasticizers (e.g., ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol), oxygen absorbers (e.g., inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), gallic acid, polyhydric phenols such as hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (e.g., a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing materials. Blends of resins with transition metals other than nickel (e.g., polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), sulfur compounds, etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0076] [Method for Manufacturing the Resin Composition] The resin composition (1) can be manufactured by mixing the EVOH resin (A) and the nickel compound by known methods, such as the dry blending method, melt mixing method, solution mixing method, impregnation method, etc. Among these, it is preferable to manufacture the resin composition by including a step of melt mixing a resin composition raw material containing the EVOH resin (A) and the nickel compound. Furthermore, these manufacturing methods can be combined as desired.

[0077] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A) and a nickel compound using a tumbler or the like.

[0078] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending pelletized EVOH resin (A) and a nickel compound, and (iii) a method of melting and kneading by adding a nickel compound to molten EVOH resin (A).

[0079] Examples of the solution mixing method include (iv) preparing a solution using a commercially available EVOH resin (A), blending a nickel compound therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of the EVOH resin, adding a nickel compound to a homogeneous solution (water / alcohol solution, etc.) of an ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0080] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound, thereby incorporating the nickel compound into the EVOH resin (A), and then drying.

[0081] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0082] In the impregnation method described above, the content ratio of nickel element (B) can be controlled by the concentration of nickel element (B) in the aqueous solution into which the EVOH resin (A) is immersed, as well as the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0083] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0084] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0085] The resin composition (1) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (1), and it is preferable that the pellet consists only of the resin composition (1). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0086] The water content of the resin composition (1) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0087] The moisture content of this resin composition (1) is measured and calculated by the following method. The pre-drying mass (W1) of this resin composition (1) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and the mass (W2) after cooling in a desiccator for 30 minutes is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0088] Furthermore, if the resin composition (1) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (1). The lower limit is usually 0% by mass.

[0089] Furthermore, the ratio of color number "1604" (R: 104, G: 72, B: 72, Brightness: 88) to color number "1877" (R: 120, G: 88, B: 88, Brightness: 104) of the resin composition (1), measured using the visual analyzer IRIS VA400 (manufactured by Alpha mos), ("1604" / "1877") is usually 1.2 or less, preferably 1.1 or less, and more preferably 1.0 or less. The smaller the ratio, the better the thermal stability tends to be. A difference of 0.1 in the ratio appears as a large difference in yield in actual manufacturing, indicating that the difference is very significant.

[0090] The resin composition (1) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when it is provided as a material for melt molding. The resin composition (1) also includes resin compositions obtained by mixing resins other than the EVOH resin (A) used in the resin composition (1).

[0091] Examples of the molded product include a single-layer film molded from the resin composition (1), and a multilayer structure having at least one layer made of the resin composition (1).

[0092] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (1)") has a layer containing the resin composition (1), and it is preferable that it has a layer consisting solely of the resin composition (1). The layer containing the resin composition (1) (hereinafter simply referred to as "the resin composition layer (1)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (1) (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0093] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0094] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0095] The layer configuration of this multilayer structure (1) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (1) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (1) and contains a mixture of this resin composition (1) and a thermoplastic resin other than this resin composition (1), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (1) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0096] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0097] In this multilayer structure (1), when an adhesive resin layer is used between the resin composition layer (1) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (1).

[0098] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0099] Lamination of the resin composition layer (1) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (1); melt-extrude lamination of the resin composition (1) onto a base resin layer; co-extrusion of the resin composition (1) and the base resin; dry lamination of the resin composition (1) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (1) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (1), and specifically, the co-extrusion method is preferred.

[0100] The multilayer structure (1) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0101] Furthermore, the multilayer structure (1) after the stretching process may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (1) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0102] When the stretched multilayer structure (1) is used as a shrink film, in order to impart heat shrinkability, the heat fixing described above may be omitted, and instead, a treatment such as applying cold air to the stretched multilayer structure (1) to cool and fix it may be performed.

[0103] The thickness of the multilayer structure (1) (including the stretched version), and furthermore, the thickness of the resin composition layer (1), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, type of base resin, type of adhesive resin, application, packaging form, required physical properties, etc. However, the thickness of the multilayer structure (1) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (1) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0104] Furthermore, the thickness ratio of the resin composition layer (1) to the base resin layer in the multilayer structure (1) (resin composition layer (1) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the thickness ratio of the resin composition layer (1) to the adhesive resin layer in the multilayer structure (1) (resin composition layer (1) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0105] Using this multilayer structure (1), it is also possible to obtain cup- or tray-shaped molded bodies and food packaging. In that case, a deep drawing method is usually employed, specifically including vacuum forming, pressure forming, vacuum pressure forming, and plug-assisted vacuum pressure forming. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0106] Single-layer films molded from this resin composition (1), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (1) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0107] <<Second Embodiment>> The second embodiment includes the following embodiments <II-1> to <II-11>. <II-1> A resin composition containing EVOH resin (A), nickel element (B), and alkali metal element, wherein at least a portion of the EVOH resin (A) is biomass-derived, the content of nickel element (B) is 0.0001 ppm or more and less than 1.0 ppm with respect to the entire resin composition, and the ratio of the content of nickel element (B) to alkali metal element in the resin composition [content of alkali metal element / content of nickel element (B)] is 200 to 600000. <II-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <II-1>, wherein the content of C is 10 ppm or more. <II-3> A resin composition according to <II-1> or <II-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <II-4> A resin composition according to any one of <II-1> to <II-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <II-5> A molding material comprising the resin composition according to any one of <II-1> to <II-4>. <II-6> A molding material according to <II-5>, wherein the molding material is in pellet form. <II-7> A multilayer structure having a layer comprising the resin composition according to any one of <II-1> to <II-4>. <II-8> A molded article comprising the multilayer structure according to <II-7>. <II-9> A food packaging article comprising the multilayer structure according to <II-7>. <II-10> A method for producing a resin composition according to any one of <II-1> to <II-4>, comprising the step of melting and mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <II-11> A method for producing a multilayer structure according to <II-7>, comprising the step of melt-molding a layer containing the resin composition.

[0108] The present invention will be described below based on examples of embodiments for carrying out the second aspect. However, the present invention is not limited to the embodiments described below.

[0109] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the Resin Composition (2)") contains at least a portion of biomass-derived EVOH resin (A), and also contains nickel element (B) and alkali metal elements. The base resin of the Resin Composition (2) is EVOH resin (A), and the content ratio of EVOH resin (A) in the Resin Composition (2) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0110] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (2) is at least partially derived from biomass, and the same type as the [EVOH resin (A)] described in the first embodiment can be used.

[0111] [Nickel Element (B)] This resin composition (2) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm relative to the entire resin composition (2), preferably 0.0001 ppm or more and less than 0.80 ppm, more preferably 0.0005 ppm or more and 0.50 ppm or less, and particularly preferably 0.0007 ppm or more and 0.40 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of the resin composition is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0112] Furthermore, the content ratio of the nickel element (B) in the resin composition (2) can be determined, for example, by heating and ashing the resin composition and acid-treating it with hydrochloric acid or the like to obtain a solution, adding pure water to a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0113] The nickel element (B) used in the resin composition (2) can be included in the resin composition as a nickel compound containing it. The nickel compound can be the same as the nickel compound described in the first embodiment above.

[0114] [Alkali metal elements] This resin composition (2) contains alkali metal elements.

[0115] The content of alkali metal elements in the resin composition (2) is preferably 10 to 2000 ppm, more preferably 50 to 1500 ppm, even more preferably 80 to 1000 ppm, and particularly preferably 100 to 500 ppm, relative to the total amount of the resin composition (2). When the content of the alkali metal compound is below the upper limit, the thermal stability tends to improve, and when it is above the lower limit, the moldability of the resin composition tends to improve.

[0116] The content of the alkali metal elements can be measured, for example, by heating the resin composition (2) to an ashing state, treating the resulting solution with hydrochloric acid or the like, adding pure water to the solution to obtain a fixed volume, and using an atomic absorption spectrophotometer as the test solution.

[0117] The ratio of nickel element (B) to alkali metal element content in the resin composition (2) [alkali metal element content / nickel element (B) content] is usually 100 to 600,000, preferably 200 to 600,000, more preferably 500 to 550,000, even more preferably 1,000 to 500,000, and particularly preferably 2,100 to 450,000. Furthermore, when the ratio of the content is below the upper limit, there is a tendency for excellent thermal stability, and when the mass ratio is above the lower limit, there is a tendency for discoloration of the molded product to be suppressed.

[0118] The alkali metal element can be included in the resin composition (2) as an alkali metal compound containing it. Examples of the alkali metal compound include alkali metal salts, oxides, hydroxides, etc. These may be used individually or in combination of two or more. Among these, the alkali metal compound is preferably water-soluble, and alkali metal salts are preferred from the viewpoint of dispersibility.

[0119] Examples of the alkali metal salt include inorganic salts of alkali metals and carboxylates of alkali metals. Among these, alkali metal carboxylates are preferred.

[0120] Examples of the alkali metal inorganic salts include alkali metal carbonates, bicarbonates, phosphates, borates, sulfates, and chlorides. Examples of alkali metal carboxylates include C2-C11 monocarboxylates such as acetate, butyrate, propionate, enantate, and caprate; C2-C11 dicarboxylates such as oxalate, malonate, succinate, adipine, suberate, and sebatate; C12 or more monocarboxylates such as laurate, palmitate, stearate, 12-hydroxystearate, behenate, and montanate; and carboxylates with polymerization terminal carboxyl groups of ethylene-vinyl alcohol resins.

[0121] Examples of alkali metal species in the alkali metal compound include lithium, sodium, potassium, rubidium, and cesium. Among these, sodium and potassium are preferred, and sodium is particularly preferred.

[0122] For these reasons, sodium compounds are preferred as the alkali metal compound, and sodium carboxylates are more preferred.

[0123] The molecular weight or formula weight of the alkali metal compound is usually 20 to 10,000, preferably 20 to 1,000, and particularly preferably 20 to 500.

[0124] Among these, sodium acetate is preferred as the alkali metal compound. Furthermore, from the viewpoint of economy and dispersibility, it is preferable to exclude inorganic layered compounds and double salts from the alkali metal compound.

[0125] It is generally known that EVOH resins undergo a color change after heating. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, leading to the formation of polyene structures in the main chain of the EVOH resin.

[0126] In contrast, the present resin composition (2) suppresses discoloration due to thermal degradation of the EVOH resin by containing nickel element (B) and alkali metal elements in combination. Normally, when nickel element is included in a resin composition, it is thought that the resin composition will become discolored due to nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel element.

[0127] However, contrary to this common technical knowledge, the present invention has found that when nickel element (B) and alkali metal elements are used in combination in a specific ratio, a resin composition in which discoloration due to thermal degradation is suppressed can be obtained.

[0128] The reason why the combination of the alkali metal element used in this resin composition and the nickel element (B) yields superior results is not clear. However, it is presumed that the combination of nickel element (B) and the alkali metal element generates interacting compounds (complexes, etc.), and these interacting compounds interact with the oxygen of the OH groups in the EVOH resin, thereby suppressing the formation of polyene structures and improving thermal stability. Furthermore, since nickel has a high ionization energy among metals, it is presumed that it is less likely to desorb after coordinating to the double bonds of the main chain of the EVOH resin, and can maintain a stable state for a relatively long period, thus exhibiting the effects of the combination.

[0129] [Other Thermoplastic Resins] The resin composition (2) may contain thermoplastic resins other than EVOH resin in a range that does not impair the effects of the present invention (for example, usually 30% by mass or less of the resin composition, preferably 20% by mass or less, more preferably 10% by mass or less, with the lower limit usually being 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of two or more.

[0130] [Other Compounding Agents] The resin composition may also contain compounding agents commonly used in EVOH resins (excluding nickel compounds and alkali metal compounds) within a range that does not impair the effects of the present invention (for example, usually 30% by mass or less of the resin composition, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of such compounding agents include titanium compounds, iron compounds, inorganic double salts (e.g., hydrotalcite), plasticizers (e.g., ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (e.g., inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), gallic acid, polyhydric phenols such as hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (e.g., combinations of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing materials. Blends of resins with transition metals other than nickel (e.g., polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), sulfur compounds, etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0131] [Other Thermoplastic Resins] The resin composition (2) may contain thermoplastic resins other than EVOH resin (A) in a range that does not impede the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of two or more.

[0132] [Other Compounding Agents] The resin composition (2) may also contain compounding agents that are generally used in EVOH resins (excluding nickel compounds and alkali metal compounds), within a range that does not impede the effects of the present invention (for example, 30% by mass or less of the resin composition (2), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (for example, ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (for example, a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing resins and transition metals other than nickel. Blends with transfer metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0133] [Method for Manufacturing the Resin Composition] The resin composition (2) can be manufactured by mixing the EVOH resin (A), nickel compound, and alkali metal compound by known methods, such as dry blending, melt mixing, solution mixing, impregnation, etc. Among these, it is preferable to manufacture the resin composition by including a step of melt mixing the resin composition raw materials containing the EVOH resin (A), nickel compound, and alkali metal compound. Furthermore, these manufacturing methods can be combined as desired.

[0134] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A), a nickel compound, and an alkali metal compound using a tumbler or the like.

[0135] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending pelletized EVOH resin (A), a nickel compound, and an alkali metal compound, and (iii) a method of melting and kneading by adding a nickel compound and an alkali metal compound to molten EVOH resin (A).

[0136] Examples of the solution mixing method include (iv) preparing a solution using commercially available EVOH resin (A), blending a nickel compound and an alkali metal compound therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of the EVOH resin, adding a nickel compound and an alkali metal compound to a homogeneous solution (water / alcohol solution, etc.) of ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0137] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound and an alkali metal compound, thereby incorporating the nickel compound and alkali metal compound into the EVOH resin (A), and then drying.

[0138] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0139] In the impregnation method described above, the content ratio of nickel element (B) can be controlled by the concentration of nickel element (B) and alkali metal elements in the aqueous solution into which the EVOH resin is immersed, as well as the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0140] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0141] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0142] The resin composition (2) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (2), and it is preferable that the pellet consists only of the resin composition (2). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0143] The water content of the resin composition (2) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0144] The moisture content of the resin composition (2) is measured and calculated by the following method: The pre-drying mass (W1) of the resin composition (2) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then weighed after cooling in a desiccator for 30 minutes (W2). The moisture content is then calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0145] Furthermore, if the resin composition (2) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (2). The lower limit is usually 0% by mass.

[0146] Using the IRIS VA400 visual analyzer (manufactured by Alpha mos) for the resin composition (2), the ratio of color number "2201" (R: 136, G: 152, B: 152, brightness: 144) to color number "1604" (R: 104, G: 72, B: 72, brightness: 88) ("2201" / "1604") is usually 11.9 or higher, preferably 12.0 or higher, and more preferably 12.5 or higher. The larger the ratio, the better the thermal stability tends to be. A difference of 0.1 in the ratio appears as a large difference in yield in actual manufacturing, indicating that the difference is very significant.

[0147] The resin composition (2) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (2) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (2).

[0148] Examples of the molded product include a single-layer film molded from the resin composition (2), and a multilayer structure having at least one layer made of the resin composition (2).

[0149] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (2)") has a layer containing the resin composition (2), and it is preferable that it has a layer consisting solely of the resin composition (2). The layer containing the resin composition (2) (hereinafter simply referred to as "the resin composition layer (2)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0150] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0151] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0152] The layer configuration of this multilayer structure (2) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (2) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (2) and contains a mixture of this resin composition (2) and a thermoplastic resin other than this resin composition (2), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (2) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0153] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0154] In this multilayer structure (2), when an adhesive resin layer is used between the resin composition layer (2) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (2).

[0155] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0156] Lamination of the resin composition layer (2) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (2); melt-extrude lamination of the resin composition (2) onto a base resin layer; co-extrusion of the resin composition (2) and the base resin; dry lamination of the resin composition (2) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (2) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (2), and specifically, the co-extrusion method is preferred.

[0157] The multilayer structure (2) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0158] Furthermore, the multilayer structure (2) after the stretching treatment may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (2) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0159] When the stretched multilayer structure (2) is used as a shrink film, in order to impart heat shrinkability, the heat fixing process described above may be omitted, and instead, a process such as applying cold air to the stretched multilayer structure (2) to cool and fix it may be performed.

[0160] The thickness of the multilayer structure (2) (including the stretched version), and furthermore, the thickness of the resin composition layer (2), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, type of base resin, type of adhesive resin, application, packaging form, required physical properties, etc. However, the thickness of the multilayer structure (2) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (2) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0161] Furthermore, the thickness ratio of the resin composition layer (2) to the base resin layer in the multilayer structure (2) (resin composition layer (2) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the thickness ratio of the resin composition layer (2) to the adhesive resin layer in the multilayer structure (2) (resin composition layer (2) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0162] It is also possible to obtain cup- or tray-shaped molded bodies and food packaging using this multilayer structure (2). In that case, deep drawing is usually employed, specifically vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0163] Single-layer films molded from this resin composition (2), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (2) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0164] <<Third Embodiment>> The third embodiment includes the following embodiments <III-1> to <III-11>. <III-1> A resin composition containing EVOH resin (A), nickel element (B), and alkaline earth metal element, wherein at least a portion of the EVOH resin (A) is biomass-derived, the content of nickel element (B) is 0.0001 ppm or more and less than 1.0 ppm with respect to the entire resin composition, and the ratio of the content of nickel element (B) to the alkaline earth metal element in the resin composition [content of alkaline earth metal element / content of nickel element (B)] is 100 to 300000. <III-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <III-1>, wherein the content of C is 10 ppm or more. <III-3> A resin composition according to <III-1> or <III-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <III-4> A resin composition according to any one of <III-1> to <III-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <III-5> A molding material comprising the resin composition according to any one of <III-1> to <III-4>. <III-6> A molding material according to <III-5>, wherein the molding material is in pellet form. <III-7> A multilayer structure having a layer comprising the resin composition according to any one of <III-1> to <III-4>. <III-8> A molded article comprising the multilayer structure according to <III-7>. <III-9> A food packaging article comprising the multilayer structure according to <III-7>. <III-10> A method for producing a resin composition according to any one of <III-1> to <III-4>, comprising the step of melting and mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <III-11> A method for producing a multilayer structure according to <III-7>, comprising the step of melt-molding a layer containing the resin composition.

[0165] The present invention will be described below based on an example of an embodiment for carrying out a third aspect. However, the present invention is not limited to the embodiments described below.

[0166] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the Resin Composition (3)") contains at least a portion of biomass-derived EVOH resin (A), and also contains nickel element (B) and alkaline earth metal element. The base resin of the Resin Composition (3) is EVOH resin (A), and the content ratio of EVOH resin (A) in the Resin Composition (3) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0167] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (3) is at least partially derived from biomass, and the same type as the [EVOH resin (A)] described in the first embodiment above can be used.

[0168] [Nickel Element (B)] This resin composition (3) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm of the total resin composition (3), more preferably 0.0003 ppm or more and less than 0.80 ppm, even more preferably 0.0005 ppm or more and 0.50 ppm or less, and particularly preferably 0.0007 ppm or more and 0.40 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of the resin composition is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0169] Furthermore, the content ratio of the nickel element (B) in the resin composition (3) can be determined, for example, by heating and ashing the resin composition and acid-treating it with hydrochloric acid or the like to obtain a solution, adding pure water to a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0170] The nickel element (B) used in this resin composition (3) can be included in the resin composition as a nickel compound containing it. As the nickel compound, the same nickel compound as described in the first embodiment above can be used.

[0171] [Alkaline Earth Metal Compounds] This resin composition (3) contains alkaline earth metal elements. The content of alkaline earth metal elements is preferably 1 to 3000 ppm, more preferably 3 to 2500 ppm, even more preferably 5 to 2000 ppm, particularly preferably 7 to 1500 ppm, and most preferably 8 to 1200 ppm, relative to the total amount of this resin composition (3). When the content of alkaline earth metal elements is below the upper limit, the thermal stability tends to be excellent, and when it is above the lower limit, the moldability of this resin composition (3) tends to be excellent.

[0172] The content of the alkaline earth metal elements can be measured, for example, by heating the resin composition (3) to a ash and then acid-treating it with hydrochloric acid or the like to obtain a solution. This solution is then diluted with pure water to a fixed volume and used as a test solution, which is then measured using an atomic absorption spectrophotometer.

[0173] The ratio of nickel element (B) to alkaline earth metal element content in this resin composition (3) [alkaline earth metal element content / nickel element (B) content] is usually 100 to 300,000, preferably 200 to 250,000, more preferably 280 to 100,000, even more preferably 300 to 50,000, particularly preferably 350 to 40,000, and most preferably 400 to 35,000. Furthermore, when the ratio of the content is below the upper limit, there is a tendency for excellent thermal stability, and when the ratio of the content is above the lower limit, there is a tendency for coloring of the molded product to be suppressed.

[0174] The aforementioned alkaline earth metal element can be included in the resin composition (3) as an alkaline earth metal compound containing it. Examples of alkaline earth metal compounds include alkaline earth metal salts, oxides, hydroxides, etc. These may be used individually or in combination of two or more. Among these, alkaline earth metal salts and alkaline earth metal oxides are preferred from the viewpoint of economy and dispersibility, and alkaline earth metal salts are particularly preferred.

[0175] Examples of the alkaline earth metal salts include inorganic salts of alkaline earth metals and carboxylates of alkaline earth metals.

[0176] Examples of inorganic salts of alkaline earth metals include carbonates, bicarbonates, phosphates, borates, sulfates, and chlorides of alkaline earth metals.

[0177] Examples of alkaline earth metal carboxylates include saturated or unsaturated carboxylates having 2 to 25 carbon atoms, preferably 2 to 22, and more preferably 6 to 20 carbon atoms. Specifically, examples include monovalent carboxylates such as acetate, butyrate, propionate, enanthate, caprate, laurate, palmitate, stearate, 12-hydroxystearate, behenate, and montanate, and divalent carboxylates such as oxalate, malonate, succinate, adipine, suberate, and sebatate. Among these, linear saturated carboxylates are preferred in terms of market availability, and monovalent carboxylates are preferred.

[0178] Examples of alkaline earth metal species in the aforementioned alkaline earth metal compound include beryllium, magnesium, calcium, strontium, barium, and radium. Among these, magnesium and calcium are preferred in terms of market availability and economic efficiency, and magnesium is particularly preferred.

[0179] Among these, magnesium oxide is preferred as the alkaline earth metal compound. Furthermore, from the viewpoint of economy and dispersibility, it is preferable to exclude layered inorganic compounds such as montmorillonite and double salts such as hydrotalcite from the alkaline earth metal compound.

[0180] Furthermore, the alkaline earth metal compound can be used in any form, such as solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, or emulsion (aqueous dispersion). Among these, powder form is preferred.

[0181] Furthermore, the alkaline earth metal compounds can be used individually or in combination of two or more types. When multiple types of alkaline earth metal compounds are used, the content ratio of alkaline earth metal elements in the resin composition (3) is the sum of the content ratios of alkaline earth metal elements in the multiple types of alkaline earth metal compounds.

[0182] It is generally known that EVOH resins undergo a color change after heating. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, leading to the formation of polyene structures in the main chain of the EVOH resin.

[0183] In contrast, the present resin composition (3) suppresses discoloration due to thermal degradation of the EVOH resin by containing nickel element (B) and alkaline earth metal elements in combination. Normally, when nickel element is included in a resin composition, it is thought that the resin composition will become discolored by nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel element.

[0184] However, contrary to this common technical knowledge, the present invention has found that when nickel element (B) and alkaline earth metal elements are used in combination in a specific ratio, a resin composition in which discoloration due to thermal degradation is suppressed can be obtained.

[0185] The reason why the combination of the alkaline earth metal element used in this resin composition (3) and the nickel element (B) yields superior results is not clear. However, it is presumed that an interacting product (complex, etc.) containing the nickel element (B) and the alkaline earth metal element is formed, and this interacting product interacts with the oxygen of the OH group in the EVOH resin, thereby suppressing the formation of the polyene structure and improving thermal stability. Furthermore, since the nickel element has a high ionization energy among metals, it is presumed that it is difficult to detach after coordinating to the double bond in the main chain of the EVOH resin, and can maintain a stable state for a relatively long time, thus exhibiting the effect of combining the two elements.

[0186] [Other Thermoplastic Resins] The resin composition (3) may contain thermoplastic resins other than EVOH resin (A) in a range that does not impede the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of two or more.

[0187] [Other Compounding Agents] The resin composition (3) may also contain compounding agents that are generally used in EVOH resins (excluding nickel compounds and alkaline earth metal compounds), within a range that does not impede the effects of the present invention (for example, 30% by mass or less of the resin composition (3), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (e.g., ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (e.g., inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (e.g., a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing resins and transition metals other than nickel. Blends with transfer metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0188] [Method for Manufacturing the Resin Composition] The resin composition (3) can be manufactured by mixing the EVOH resin (A), nickel compound, and alkaline earth metal compound by known methods, such as the dry blending method, melt mixing method, solution mixing method, impregnation method, etc. Among these, it is preferable to manufacture the resin composition by including a step of melt mixing the resin composition raw materials containing the EVOH resin (A), nickel compound, and alkaline earth metal compound. Furthermore, these manufacturing methods can be combined as desired.

[0189] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A), a nickel compound, and an alkaline earth metal compound using a tumbler or the like.

[0190] Examples of the melt-mixing method include (ii) a method of melt-kneading a dry blend obtained by dry-blending pelletized EVOH resin (A), a nickel compound, and an alkaline earth metal compound, and (iii) a method of melt-kneading by adding a nickel compound and an alkaline earth metal compound to molten EVOH resin (A).

[0191] Examples of the solution mixing method include (iv) preparing a solution using commercially available EVOH resin (A), blending a nickel compound and an alkaline earth metal compound therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of EVOH resin, adding a nickel compound and an alkaline earth metal compound to a homogeneous solution (water / alcohol solution, etc.) of ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0192] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound and an alkaline earth metal compound, thereby incorporating the nickel compound and the alkaline earth metal compound into the EVOH resin (A), and then drying.

[0193] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0194] In the impregnation method described above, the content ratio of nickel element (B) can be controlled by the concentration of nickel element (B) and alkaline earth metal elements in the aqueous solution into which the EVOH resin is immersed, as well as by the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0195] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0196] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0197] The resin composition (3) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but it is preferable to be in pellet form as it is easier to obtain the effects of the present invention. The pellets contain the resin composition (3), and it is preferable that the pellets consist only of the resin composition (3). The shape of the pellets may be spherical, oval, cylindrical, cubic, or rectangular, but they are usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0198] The water content of the resin composition (3) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0199] The moisture content of the resin composition (3) is measured and calculated by the following method: The pre-drying mass (W1) of the resin composition (3) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then weighed after cooling in a desiccator for 30 minutes (W2). The moisture content is then calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0200] Furthermore, if the resin composition (3) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (3). The lower limit is usually 0% by mass.

[0201] Furthermore, the ratio of color number "1604" (R: 104, G: 72, B: 72) to color number "2168" (R: 136, G: 120, B: 136) of the resin composition (3), measured using the visual analyzer IRIS VA400 (manufactured by Alpha mos), ("1604" / "2168") is usually 3.0 or less, and preferably 2.9 or less. The smaller the ratio, the better the thermal stability tends to be. A difference of 0.1 in the ratio appears as a large difference in yield in actual manufacturing, indicating that the difference is very significant.

[0202] The resin composition (3) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (3) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (3).

[0203] Examples of the molded product include a single-layer film molded from the resin composition (3), and a multilayer structure having at least one layer made of the resin composition (3).

[0204] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (3)") has a layer containing the resin composition (3), and it is preferable that it has a layer consisting solely of the resin composition (3). The layer containing the resin composition (3) (hereinafter simply referred to as "the resin composition layer (3)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0205] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0206] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0207] The layer configuration of this multilayer structure (3) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (3) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (3) and contains a mixture of this resin composition (3) and a thermoplastic resin other than this resin composition (3), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (3) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0208] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0209] In this multilayer structure (3), when an adhesive resin layer is used between the resin composition layer (3) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (3).

[0210] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0211] Lamination of the resin composition layer (3) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (3); melt-extrude lamination of the resin composition (3) onto a base resin layer; co-extrusion of the resin composition (3) and the base resin; dry lamination of the resin composition (3) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (3) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (3), and specifically, the co-extrusion method is preferred.

[0212] The multilayer structure (3) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0213] Furthermore, the multilayer structure (3) after the stretching process may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (3) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0214] When the stretched multilayer structure (3) is used as a shrink film, in order to impart heat shrinkability, the heat fixing described above may be omitted, and instead, a treatment such as applying cold air to the stretched multilayer structure (3) to cool and fix it may be performed.

[0215] The thickness of the multilayer structure (3) (including the stretched version), and furthermore, the thickness of the resin composition layer (3), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, type of base resin, type of adhesive resin, application, packaging form, required physical properties, etc. However, the thickness of the multilayer structure (3) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (3) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0216] Furthermore, the ratio of the thickness of the resin composition layer (3) to the base resin layer in the multilayer structure (3) (resin composition layer (3) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the ratio of the thickness of the resin composition layer (3) to the adhesive resin layer in the multilayer structure (3) (resin composition layer (3) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0217] Using this multilayer structure (3), it is also possible to obtain cup- or tray-shaped molded bodies and food packaging. In that case, a deep drawing method is usually employed, specifically including vacuum forming, pressure forming, vacuum pressure forming, and plug-assisted vacuum pressure forming. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0218] Single-layer films molded from this resin composition (3), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (3) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0219] <<Fourth Embodiment>> The fourth embodiment includes the following embodiments <IV-1> to <IV-11>. <IV-1> A resin composition containing EVOH resin (A), nickel element (B), and boron element, wherein at least a portion of the EVOH resin (A) is biomass-derived, the content of nickel element (B) is 0.0001 ppm or more and less than 1.0 ppm with respect to the entire resin composition, and the ratio of the content of nickel element (B) to the content of boron element in the resin composition [content of boron element / content of nickel element (B)] is 1,000 to 600,000. <IV-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <IV-1>, wherein the content of C is 10 ppm or more. <IV-3> A resin composition according to <IV-1> or <IV-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <IV-4> A resin composition according to any one of <IV-1> to <IV-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <IV-5> A molding material comprising the resin composition according to any one of <IV-1> to <IV-4>. <IV-6> A molding material according to <IV-5>, wherein the molding material is in pellet form. <IV-7> A multilayer structure having a layer comprising the resin composition according to any one of <IV-1> to <IV-4>. <IV-8> A molded article comprising the multilayer structure according to <IV-7>. <IV-9> A food packaging article comprising the multilayer structure according to <IV-7>. <IV-10> A method for producing a resin composition according to any one of <IV-1> to <IV-4>, comprising the step of melting and mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <IV-11> A method for producing a multilayer structure according to <IV-7>, comprising the step of melt-molding a layer containing the resin composition.

[0220] The present invention will be described below based on an example of an embodiment for carrying out the fourth aspect. However, the present invention is not limited to the embodiments described below.

[0221] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition (4)") contains at least a portion of biomass-derived EVOH resin (A), and also contains nickel element (B) and boron element. The base resin of the resin composition (4) is EVOH resin (A), and the content ratio of EVOH resin (A) in the resin composition (4) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0222] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (4) is at least partially derived from biomass, and the same type as the [EVOH resin (A)] described in the first embodiment can be used.

[0223] [Nickel Element (B)] This resin composition (4) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm of the total resin composition (4), more preferably 0.0001 ppm or more and 0.80 ppm or less, even more preferably 0.0005 ppm or more and 0.50 ppm or less, and particularly preferably 0.0007 ppm or more and 0.40 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of the resin composition is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0224] Furthermore, the content ratio of the nickel element (B) in the resin composition (4) can be determined, for example, by heating and ashing the resin composition and acid-treating it with hydrochloric acid or the like to obtain a solution, adding pure water to a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0225] The nickel element (B) used in this resin composition (4) can be included in the resin composition as a nickel compound containing it. As the nickel compound, the same nickel compound as described in the first embodiment above can be used.

[0226] [Boron Element] This resin composition (4) contains the element boron. The content of the element boron is preferably 1 to 5000 ppm, more preferably 10 to 3000 ppm, even more preferably 50 to 1000 ppm, and particularly preferably 100 to 500 ppm, relative to the entire resin composition (4). When the content of the element boron is below the upper limit, the resin composition (4) tends to have excellent thermal stability, and when it is above the lower limit, the resin composition (4) tends to have excellent moldability.

[0227] The boron content in the resin composition (4) can be measured, for example, by the following method. Specifically, 0.1 g of the resin composition (4) is first treated with concentrated nitric acid by microwave decomposition to obtain a solution, which is then diluted to a fixed volume (0.75 mg / mL) with pure water to be used as the test solution, and measured using an inductively coupled plasma emission spectrometer (ICP-AES) (Agilent Technologies, 720-ES model). The boron content measured in this way corresponds to the boron content derived from boron compounds.

[0228] Furthermore, if the resin composition (4) is a molded product combined with other thermoplastic resins, for example, if it is a multilayer structure, the layer made of the resin composition to be measured can be removed from the multilayer structure by any method, and then the boron content can be quantified in the same manner as described above.

[0229] The ratio of nickel element (B) to boron element in the resin composition [boron element content / nickel element (B) content] is usually 1,000 to 600,000, preferably 1,500 to 500,000, and more preferably 1,800 to 450,000. Furthermore, when the ratio of the content is below the upper limit, the thermal stability tends to be excellent, and when the ratio of the content is above the lower limit, the discoloration of the molded product tends to be suppressed.

[0230] The boron element can be included in the resin composition (4) as a boron compound containing it. Examples of boron compounds used in the resin composition (4) include boric acid or its metal salts, such as sodium borate (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.), potassium borate (potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate, etc.), lithium borate (lithium metaborate, lithium tetraborate, lithium pentaborate, etc.), calcium borate, barium borate (barium orthoborate, barium metaborate, barium diborate, barium tetraborate, etc.), magnesium borate (magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc.), manganese borate (boric acid Manganese 1, manganese metaborate, manganese tetraborate, etc.), cobalt borate, zinc borate (zinc tetraborate, zinc metaborate, etc.), cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.), silver borate (silver metaborate, silver tetraborate, etc.), copper borate (copper dicorate, copper metaborate, copper tetraborate, etc.), nickel borate (nickel orthoborate, nickel diborate, nickel tetraborate) Examples include boron, nickel octaborate, potassium aluminum borate, ammonium borate (ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate, etc.), lead borate (lead metaborate, lead hexaborate, etc.), bismuth borate, etc., as well as elemental boron, borax, kernite, inyoite, kotoite, syuanite, zyberite, and other borate minerals. Among these, borax and boric acid are preferably used. These can be used individually or in combination of two or more.

[0231] The boron compound can be used in any form, such as solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, or emulsion (aqueous dispersion), but powder form is preferred.

[0232] It is generally known that EVOH resins undergo a color change after heating. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, leading to the formation of polyene structures in the main chain of the EVOH resin.

[0233] In contrast, the present resin composition (4) suppresses discoloration due to thermal degradation of the EVOH resin by containing nickel element (B) and boron element in combination. Normally, when nickel element is included in a resin composition, it is thought that the resin composition will become discolored due to nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel element.

[0234] However, contrary to this common technical understanding, the present invention has found that when nickel element (B) and boron element are used in combination in a specific ratio, a resin composition in which discoloration due to thermal degradation is suppressed can be obtained. The reason why the boron element used in this resin composition (4) and the nickel element (B) are used in combination is not clear, but it is presumed that an interacting product (complex, etc.) containing nickel element (B) and boron element is formed, and this interacting product interacts with the oxygen of the OH group in the EVOH resin, thereby suppressing the formation of the polyene structure and improving thermal stability. Furthermore, since nickel element has a high ionization energy among metals, it is presumed that it does not easily desorb after coordinating to the double bond of the main chain of the EVOH resin, and can maintain a stable state for a relatively long time, thus exhibiting the effect of being used in combination.

[0235] [Other Thermoplastic Resins] The resin composition (4) may contain thermoplastic resins other than the EVOH resin (A) in a range that does not impede the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of two or more.

[0236] [Other Compounding Agents] The resin composition (4) may also contain compounding agents that are generally used in EVOH resins (excluding nickel compounds and boron compounds), within a range that does not impede the effects of the present invention (for example, 30% by mass or less of the resin composition (4), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (for example, ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (for example, a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing resins and transition metals other than nickel. Blends with transfer metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0237] [Method for Manufacturing the Resin Composition] The resin composition (4) can be manufactured by mixing the EVOH resin (A), nickel compound, and boron compound by known methods, such as dry blending, melt mixing, solution mixing, impregnation, etc. Among these, it is preferable to manufacture the resin composition by including a step of melt mixing the resin composition raw materials containing the EVOH resin (A), nickel compound, and boron compound. Furthermore, these manufacturing methods can be combined in any way.

[0238] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A), a nickel compound, and a boron compound using a tumbler or the like.

[0239] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending pelletized EVOH resin (A), a nickel compound, and a boron compound, and (iii) a method of melting and kneading by adding a nickel compound and a boron compound to molten EVOH resin (A).

[0240] Examples of the solution mixing method include (iv) preparing a solution using commercially available EVOH resin (A), blending a nickel compound and a boron compound therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of EVOH resin, adding a nickel compound and a boron compound to a homogeneous solution (water / alcohol solution, etc.) of ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0241] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound and a boron compound, thereby incorporating the nickel compound and boron compound into the EVOH resin (A), and then drying.

[0242] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0243] In the impregnation method described above, the content ratio of nickel element (B) and boron element can be controlled by the concentration of nickel element (B) and boron element in the aqueous solution into which the EVOH resin is immersed, as well as the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0244] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0245] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0246] The resin composition (4) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (4), and it is preferable that the pellet consists only of the resin composition (4). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0247] The water content of the resin composition (4) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0248] The moisture content of this resin composition (4) is measured and calculated by the following method. The pre-drying mass (W1) of this resin composition (4) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and the mass (W2) after cooling in a desiccator for 30 minutes is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0249] Furthermore, if the resin composition (4) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (4). The lower limit is usually 0% by mass.

[0250] Furthermore, the ratio of color number "1877" (R: 120, G: 88, B: 88) to color number "2441" (R: 152, G: 136, B: 152), measured using the Visual Analyzer IRIS VA400 (Alpha mos), is less than 1.2. A smaller ratio indicates that dark red coloration can be suppressed.

[0251] Furthermore, the ratio of color number "1621" (R: 104, G: 88, B: 88) to color number "2201" (R: 136, G: 152, B: 152) ("1621" / "2201") is 1.2 or less. A smaller ratio means that the dark red tinting can be suppressed.

[0252] In other words, if the values ​​of "1877" / "2441" and "1621" / "2201" fall within the aforementioned ranges, it means that the resin composition (4) has excellent thermal stability. The brightness is represented by the sum of the maximum and minimum values ​​of the RGB values ​​divided by two. A higher brightness value indicates a lighter coloration. A difference of 0.1 in the ratios is considered very large, as it results in a significant difference in yield during actual manufacturing.

[0253] The resin composition (4) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (4) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (4).

[0254] Examples of the molded product include a single-layer film molded from the resin composition (4), and a multilayer structure having at least one layer made of the resin composition (4).

[0255] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (4)") has a layer containing the resin composition (4), and it is preferable that it has a layer consisting solely of the resin composition (4). The layer containing the resin composition (4) (hereinafter simply referred to as "the resin composition layer (4)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0256] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0257] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0258] The layer configuration of this multilayer structure (4) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (4) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (4) and contains a mixture of this resin composition (4) and a thermoplastic resin other than this resin composition (4), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (4) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0259] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0260] In this multilayer structure (4), when an adhesive resin layer is used between the resin composition layer (4) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (4).

[0261] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0262] Lamination of the resin composition layer (4) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (4); melt-extrude lamination of the resin composition (4) onto a base resin layer; co-extrusion of the resin composition (4) and the base resin; dry lamination of the resin composition (4) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (4) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (4), and specifically, the co-extrusion method is preferred.

[0263] The multilayer structure (4) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0264] Furthermore, the multilayer structure (4) after the stretching process may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (4) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0265] When the stretched multilayer structure (4) is used as a shrink film, in order to impart heat shrinkability, the heat fixing described above may be omitted, and instead, a treatment such as applying cold air to the stretched multilayer structure (4) to cool and fix it may be performed.

[0266] The thickness of the multilayer structure (4) (including the stretched version), and furthermore, the thickness of the resin composition layer (4), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, type of base resin, type of adhesive resin, application, packaging form, required physical properties, etc. However, the thickness of the multilayer structure (4) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (4) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0267] Furthermore, the ratio of the thickness of the resin composition layer (4) to the base resin layer in the multilayer structure (4) (resin composition layer (4) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the ratio of the thickness of the resin composition layer (4) to the adhesive resin layer in the multilayer structure (4) (resin composition layer (4) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0268] Using this multilayer structure (4), it is also possible to obtain cup- or tray-shaped molded bodies and food packaging. In that case, a deep drawing method is usually employed, specifically including vacuum forming, pressure forming, vacuum pressure forming, and plug-assisted vacuum pressure forming. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0269] Single-layer films molded from this resin composition (4), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (4) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0270] <<Fifth Embodiment>> The fifth embodiment includes the following embodiments <V-1> to <V-11>. <V-1> A resin composition containing EVOH resin (A), nickel element (B), and a lubricant, wherein at least a portion of the EVOH resin (A) is biomass-derived, the content of the nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm with respect to the whole resin composition, and the ratio of the content of the nickel element (B) to the lubricant in the resin composition [content of lubricant / content of nickel element (B)] is 200 to 600000. <V-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <V-1>, wherein the content of C is 10 ppm or more. <V-3> A resin composition according to <V-1> or <V-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <V-4> A resin composition according to any one of <V-1> to <V-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <V-5> A molding material comprising the resin composition according to any one of <V-1> to <V-4>. <V-6> A molding material according to <V-5>, wherein the molding material is in pellet form. <V-7> A multilayer structure having a layer comprising the resin composition according to any one of <V-1> to <V-4>. <V-8> A molded article comprising the multilayer structure according to <V-7>. <V-9> A food packaging article comprising the multilayer structure according to <V-7>. <V-10> A method for producing a resin composition according to any one of <V-1> to <V-4>, comprising the step of melting and mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <V-11> A method for producing a multilayer structure according to <V-7>, comprising the step of melt-molding a layer containing the resin composition.

[0271] The present invention will be described below based on an example of an embodiment for carrying out the fifth aspect. However, the present invention is not limited to the embodiments described below.

[0272] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition (5)") contains at least a portion of biomass-derived EVOH resin (A), and also contains nickel element (B) and a lubricant. The base resin of the resin composition (5) is EVOH resin (A), and the content ratio of EVOH resin (A) in the resin composition (5) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0273] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (5) is at least partially derived from biomass, and the same type as the [EVOH resin (A)] described in the first embodiment can be used.

[0274] [Nickel Element (B)] This resin composition (5) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm of the total resin composition (5), more preferably 0.0001 ppm or more and less than 0.80 ppm, even more preferably 0.0005 ppm or more and 0.50 ppm or less, and particularly preferably 0.0007 ppm or more and 0.40 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of the resin composition is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0275] Furthermore, the content ratio of the nickel element (B) in the resin composition (5) can be determined, for example, by heating and ashing the resin composition and acid-treating it with hydrochloric acid or the like to obtain a solution, adding pure water to a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0276] The nickel element (B) used in this resin composition (5) can be included in the resin composition as a nickel compound containing it. As the nickel compound, the same nickel compound as described in the first embodiment above can be used.

[0277] [Lubricant] Examples of the lubricant include higher fatty acids having 12 to 25 carbon atoms, preferably 13 to 23 carbon atoms, and more preferably 15 to 20 carbon atoms. Examples of the higher fatty acids include higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and oleic acid; metal salts of these higher fatty acids such as aluminum salts, calcium salts, zinc salts, magnesium salts, and barium salts; esters of the higher fatty acids such as methyl esters, isopropyl esters, butyl esters, and octyl esters; saturated higher fatty acid amides such as stearic acid amide and behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide and erucic acid amide; and amides of higher fatty acids such as bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, and ethylenebis-lauric acid amide. Other lubricants besides the aforementioned higher fatty acids include, for example, low molecular weight polyethylene, low molecular weight polypropylene, or acid-modified products thereof, low molecular weight polyolefins, higher alcohols, ester oligomers, and fluoroethylene resins, with molecular weights of approximately 500 to 10,000. These lubricants can be used individually or in combination of two or more.

[0278] Furthermore, the valency of the aforementioned higher fatty acids is usually 1 to 5, preferably 1 to 3, and particularly preferably 1 to 2, from the viewpoint of extrusion stability and market availability. The valency refers to the number of structures derived from higher fatty acids in one molecule of the compound used as a lubricant. For example, when bis-stearic acid amide is used as a lubricant, it has two structures derived from a higher fatty acid molecule with 18 carbon atoms in one molecule, so it is an amide of a higher fatty acid with 18 carbon atoms, and the valency of the higher fatty acid is considered to be 2.

[0279] Among the lubricants mentioned above, preferred are higher fatty acids, metal salts of higher fatty acids, esters of higher fatty acids, and amides of higher fatty acids; particularly preferred are metal salts of higher fatty acids and amides of higher fatty acids; even more preferably, from the viewpoint of extrusion stability, are amides of higher fatty acids, and particularly preferred are ethylenebisstearic acid amides.

[0280] The lubricant can be in any form, such as solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, or emulsion (aqueous dispersion). Powder form is preferred. The particle size of the powdered lubricant is typically 0.1 to 100 μm, preferably 1 to 75 μm, and particularly preferably 5 to 50 μm.

[0281] The lubricant content is preferably 10 ppm to 2000 ppm, more preferably 50 ppm to 1850 ppm, and even more preferably 100 ppm to 1400 ppm, relative to the mass of the resin composition (5). When the lubricant content is below the upper limit, the thermal stability tends to be excellent, and when it is above the lower limit, the moldability of the resin composition (5) tends to be excellent.

[0282] The lubricant content can be measured, for example, by the following method. If the lubricant is, for example, a higher fatty acid amide, the total amount of nitrogen in the composition can be measured using a trace total nitrogen analyzer and converted to the lubricant content to determine the lubricant content in the composition.

[0283] The ratio of nickel element (B) to lubricant content in this resin composition (5) [lumbant content / nickel element (B) content] is usually 200 to 600,000, preferably 300 to 550,000, more preferably 1,000 to 500,000, particularly preferably 10,000 to 450,000, and most preferably 15,000 to 430,000. Furthermore, when the ratio of the content is below the upper limit, there is a tendency for excellent thermal stability, and when the mass ratio is above the lower limit, there is a tendency for discoloration of the molded product to be suppressed.

[0284] It is generally known that EVOH resins become discolored when heated. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, which in turn lead to the formation of polyene structures in the main chain of the EVOH resin.

[0285] In contrast, the present resin composition (5) suppresses discoloration due to thermal degradation of the EVOH resin by containing nickel element (B) and a lubricant in combination. Normally, when nickel element is included in a resin composition, it is thought that the resin composition will become discolored due to nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel element.

[0286] However, contrary to this common technical knowledge, the present invention has found that when nickel element (B) and a lubricant are used in combination in a specific ratio, a resin composition in which discoloration due to thermal degradation is suppressed can be obtained.

[0287] The reason why superior effects can be obtained by using the lubricant in this resin composition (5) and the nickel element (B) in combination is not clear, but it is presumed that the effects obtained when each is added individually are not canceled out but instead exert a synergistic effect, thereby improving thermal stability. Furthermore, since nickel has a high ionization energy among metals, it is not easily desorbed after coordinating to the double bond in the main chain of the EVOH resin, and it is presumed that the effect of using them together is due to the fact that it can maintain a stable state for a relatively long time.

[0288] [Other Thermoplastic Resins] The resin composition (5) may contain thermoplastic resins other than the EVOH resin (A) in a range that does not impede the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of two or more.

[0289] [Other Compounding Agents] The resin composition (5) may also contain compounding agents that are generally used in EVOH resins (excluding nickel compounds and lubricants), within a range that does not impede the effects of the present invention (for example, usually 30% by mass or less of the resin composition (5), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (for example, ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (for example, a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing resins and transition metals other than nickel. Blends with transfer metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0290] [Method for Manufacturing the Resin Composition] The resin composition (5) can be manufactured by mixing the EVOH resin (A), nickel compound, and lubricant by known methods, such as dry blending, melt mixing, solution mixing, and impregnation. Among these methods, it is preferable to manufacture the resin composition by including a step of melt mixing the resin composition raw materials containing the EVOH resin (A), nickel compound, and lubricant. Furthermore, these manufacturing methods can be combined in any way.

[0291] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A), a nickel compound, and a lubricant using a tumbler or the like.

[0292] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending pelletized EVOH resin (A), a nickel compound, and a lubricant, and (iii) a method of melting and kneading by adding a nickel compound and a lubricant to molten EVOH resin (A).

[0293] Examples of the solution mixing method include (iv) preparing a solution using commercially available EVOH resin (A), blending a nickel compound and a lubricant therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of EVOH resin, adding a nickel compound and a lubricant to a homogeneous solution (water / alcohol solution, etc.) of ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0294] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound and a lubricant, the nickel compound and lubricant are incorporated into the EVOH resin (A), and then dried.

[0295] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0296] In the impregnation method described above, the proportion of nickel element (B) and lubricant can be controlled by the concentration of nickel element (B) and lubricant in the aqueous solution into which the EVOH resin is immersed, as well as by the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0297] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0298] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0299] The resin composition (5) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (5), and it is preferable that the pellet consists only of the resin composition (5). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0300] The water content of the resin composition (5) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0301] The moisture content of this resin composition (5) is measured and calculated by the following method. The pre-drying mass (W1) of this resin composition (5) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and the mass (W2) after cooling in a desiccator for 30 minutes is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0302] Furthermore, the ratio of color number "2457" (R: 152, G: 152, B: 152) to color number "1605" (R: 104, G: 72, B: 88) of the resin composition (5), measured using the visual analyzer IRIS VA400 (manufactured by Alpha mos), ("2457" / "1605") is usually greater than 32.0. The larger the ratio, the better the thermal stability tends to be. A difference of 0.1 in the ratio appears as a large difference in yield in actual manufacturing, indicating that the difference is very significant.

[0303] Furthermore, even when heated during melt molding, this resin composition (5) exhibits suppressed color change and excellent long-run performance, with a ratio of the YI value after heating (YI value after heating / YI value before heating) to the YI value before heating being 2.8 or less. When the ratio of the YI value after heating to the YI value before heating is within the above range, there is a tendency for color change to be further suppressed.

[0304] The YI value before heating is obtained by crushing the resin composition (5) into 1 to 5 mm cubes, filling the resulting powder or pellets into a cylinder with an inner diameter of 32 mm and a height of 30 mm, and measuring the leveled surface using a spectrophotometer ZE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.). The YI value after heating is obtained by heating the resin composition (5) crushed into 1 to 5 mm cubes in an oven under a nitrogen atmosphere at 150°C for 5 hours and measuring the value using the same method.

[0305] The resin composition (5) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (5) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (5).

[0306] Examples of the molded product include a single-layer film molded from the resin composition (5), and a multilayer structure having at least one layer made of the resin composition (5).

[0307] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (5)") has a layer containing the resin composition (5), and it is preferable that it has a layer consisting solely of the resin composition (5). The layer containing the resin composition (5) (hereinafter simply referred to as "the resin composition layer (5)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0308] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0309] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0310] The layer configuration of this multilayer structure (5) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (5) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (5) and contains a mixture of this resin composition (5) and a thermoplastic resin other than this resin composition (5), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (5) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0311] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0312] In this multilayer structure (5), when an adhesive resin layer is used between the resin composition layer (5) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (5).

[0313] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0314] Lamination of the resin composition layer (5) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (5); melt-extrude lamination of the resin composition (5) onto a base resin layer; co-extrusion of the resin composition (5) and the base resin; dry lamination of the resin composition (5) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (5) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (5), and specifically, the co-extrusion method is preferred.

[0315] The multilayer structure (5) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0316] Furthermore, the multilayer structure (5) after the stretching treatment may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (5) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0317] When the stretched multilayer structure (5) is used as a shrink film, in order to impart heat shrinkability, the heat fixing described above may be omitted, and instead, a treatment such as applying cold air to the stretched multilayer structure (5) to cool and fix it may be performed.

[0318] The thickness of the multilayer structure (5) (including the stretched version), and furthermore, the thickness of the resin composition layer (5), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, type of base resin, type of adhesive resin, application, packaging form, required physical properties, etc. However, the thickness of the multilayer structure (5) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (5) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0319] Furthermore, the thickness ratio of the resin composition layer (5) to the base resin layer in the multilayer structure (5) (resin composition layer (5) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the thickness ratio of the resin composition layer (5) to the adhesive resin layer in the multilayer structure (5) (resin composition layer (5) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0320] It is also possible to obtain cup- or tray-shaped molded bodies and food packaging using this multilayer structure (5). In that case, deep drawing is usually employed, specifically vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0321] Single-layer films molded from this resin composition (5), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (5) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0322] <<Sixth Embodiment>> The sixth embodiment includes the following embodiments <VI-1> to <VI-12>. <VI-1> A resin composition comprising an EVOH resin (A), a nickel element (B), and a polyamide resin, wherein at least a portion of the EVOH resin (A) is biomass-derived, and the content ratio of the nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm with respect to the entire resin composition. <VI-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <VI-1>, wherein the content of C is 10 ppm or more. <VI-3> A resin composition according to <VI-1> or <VI-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <VI-4> A resin composition according to any one of <VI-1> to <VI-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <VI-5> A resin composition in which the content of nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm with respect to the entire resin composition. <VI-6> A molding material comprising the resin composition according to any one of <VI-1> to <VI-5>. <VI-7> A molding material according to <VI-6>, wherein the molding material is in pellet form. <VI-8> A multilayer structure having a layer comprising the resin composition according to any one of <VI-1> to <VI-6>. <VI-9> A molded article comprising the multilayer structure described in <VI-8>. <VI-10> A food packaging comprising the multilayer structure described in <VI-8>. <VI-11> A method for producing a resin composition described in any of <VI-1> to <VI-5>, comprising the step of melt-mixing resin composition raw materials containing the EVOH resin (A) and nickel element (B). <VI-12> A method for producing a multilayer structure described in <VI-8>, comprising the step of melt-molding a layer containing the resin composition.

[0323] The present invention will be described below based on an example of an embodiment for carrying out the sixth aspect. However, the present invention is not limited to the embodiments described below.

[0324] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition (6)") contains at least a portion of biomass-derived EVOH resin (A), and also contains nickel element (B) and polyamide resin. The base resin of the resin composition (6) is EVOH resin (A), and the content ratio of EVOH resin (A) in the resin composition (6) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0325] [EVOH resin (A)] The EVOH resin (A) used in this resin composition (6) is at least partially derived from biomass, and the same type as the [EVOH resin (A)] described in the first embodiment can be used.

[0326] [Nickel Element (B)] This resin composition (6) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm relative to the entire resin composition (6), preferably 0.0001 ppm or more and less than 0.50 ppm, more preferably 0.0003 ppm or more and 0.30 ppm or less, and even more preferably 0.0005 ppm or more and 0.10 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of the resin composition is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0327] Furthermore, the content ratio of the nickel element (B) in the resin composition (6) can be determined, for example, by heating and ashing the resin composition and acid-treating it with hydrochloric acid or the like to obtain a solution, adding pure water to a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0328] The nickel element (B) used in this resin composition (6) can be included in the resin composition as a nickel compound containing it. As the nickel compound, the same nickel compound as described in the first embodiment above can be used.

[0329] [Polyamide resin] The polyamide resin used in this resin composition (6) is a known resin, a water-insoluble thermoplastic resin, and a known general-purpose polyamide resin can be used.

[0330] Examples of the polyamide resins include homopolymers such as polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), and polylauryl lactam (nylon 12). Furthermore, the copolymerized polyamide resins include polyethylenediamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sevacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam / lauryl lactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon 12 / 66), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon 26 / 66), Examples include aliphatic polyamides such as caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610) and ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610), aromatic polyamides such as polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, and poly-p-phenylene-3,4'diphenyl ether terephthalamide, amorphous polyamides, and these polyamide resins modified with aromatic amines such as methylenebenzylamine and metaxylylenediamine, or metaxylylenediammonium adipate. Alternatively, these may be end-modified polyamide resins, and end-modified polyamide resins are preferred. These polyamide resins can be used individually or in combination of two or more types.Among these, homopolymer polyamide resins are preferred, and polycapramid (nylon 6) is particularly preferred.

[0331] The aforementioned polyamide resin tends to have a high bonding strength with resins containing polar groups, such as EVOH resin.

[0332] The ratio of amide bonds in the amide monomer units constituting the polyamide resin is preferably 20 to 60%, more preferably 30 to 50%, and particularly preferably 35 to 45%, when calculated as the molecular weight ratio of the amide monomer units (for example, in the case of nylon 6, the amide bonds (-CONH-) in [-C6H5-CONH-]). When the ratio of amide bonds is above the lower limit, the bonding strength at the interface with polar resins such as EVOH resin tends to be excellent, and when it is below the upper limit, the reactivity with polar resins such as EVOH resin during melt molding is good, which suppresses roughness at the adhesive interface when co-extruded and tends to result in a superior appearance.

[0333] Furthermore, the melting point of the polyamide resin is preferably 160 to 270°C, more preferably 175 to 250°C, and particularly preferably 190 to 230°C. When the melting point of the polyamide resin is above the lower limit, the heat resistance of the multilayer structure tends to be good. On the other hand, when the melting point of the polyamide resin is below the upper limit, in the case of a multilayer structure that includes other resin layers, the difference in melting points between the resin used in the other layers becomes small, and when co-extruded with other resins, layer disorder is less likely to occur at the time of merging, and the appearance of the multilayer structure tends to be excellent.

[0334] From the above viewpoint, preferred polyamide resins are polyamides having a melting point of 160 to 270°C, more preferably 175 to 250°C, particularly preferably 190 to 230°C, and an amide bond ratio of 20 to 60%, more preferably 30 to 50%, and particularly preferably 35 to 45%. Specifically, for example, nylon 6 (melting point: about 220°C, amide bond ratio: 38%) and nylon 6 / 66 (melting point: about 200°C, amide bond ratio: 38%) are preferred.

[0335] The degree of polymerization of polyamide resin can be indicated by its relative viscosity, which is measured according to JIS K6810. It is generally preferably 1.5 to 6, more preferably 2.0 to 6, and even more preferably 2.5 to 5. If the relative viscosity is too low, the extruder tends to enter a high-torque state during molding, making extrusion difficult. If it is too high, the thickness accuracy of the resulting film or sheet tends to decrease. The relative viscosity can be measured according to JIS K6810 by completely dissolving 1 g of polyamide resin in 100 mL of 96% concentrated sulfuric acid and measuring it using a capillary viscometer at 25°C.

[0336] The polyamide resin content in the resin composition (6) is typically 5 to 40% by mass, preferably 8 to 38% by mass, and more preferably 10 to 35% by mass, relative to the resin composition (6). When the value is within this range, the effects of the present invention tend to be obtained more effectively.

[0337] The mass ratio of the EVOH resin (A) to the polyamide resin (EVOH resin (A) / polyamide resin) is typically 95 / 5 to 50 / 50, preferably 92 / 8 to 70 / 30, and more preferably 90 / 10 to 80 / 20. When the mass ratio is below the upper limit, the thermal stability tends to be excellent, and when the mass ratio is above the lower limit, the discoloration of the molded product tends to be suppressed.

[0338] [Other Thermoplastic Resins] The resin composition (6) may contain thermoplastic resins other than EVOH resin (A) and polyamide resin in a range that does not impede the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Other thermoplastic resins that can be used are known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used alone or in combination of two or more.

[0339] [Other Compounding Agents] The resin composition (6) may also contain compounding agents (excluding nickel compounds) that are generally used in EVOH resins, within a range that does not impede the effects of the present invention (for example, 30% by mass or less of the resin composition (6), preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (for example, ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, and further its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (for example, a combination of polypropylene and cobalt), and carbon-carbon unsaturated bond-containing resins and transition metals other than nickel. Blends with transfer metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those obtained by adding photoinitiators (e.g., benzophenone), antioxidants or deodorants other than those mentioned above (e.g., activated carbon), heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc., may also be incorporated. These compounds can be used individually or in combination of two or more.

[0340] [Method for Manufacturing the Resin Composition] The resin composition (6) can be manufactured by mixing the EVOH resin (A), nickel compound, and polyamide resin by known methods, such as dry blending, melt mixing, solution mixing, and impregnation. Among these methods, it is preferable to manufacture the composition by including a step of melt mixing the composition raw materials containing the EVOH resin (A), nickel compound, and polyamide resin. Furthermore, these manufacturing methods can be combined in any way.

[0341] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A), a nickel compound, and a polyamide resin using a tumbler or the like.

[0342] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending pelletized EVOH resin (A), a nickel compound, and a polyamide resin, and (iii) a method of melting and kneading by adding a nickel compound and a polyamide resin to molten EVOH resin (A).

[0343] Examples of the solution mixing method include (iv) preparing a solution using commercially available EVOH resin (A), blending a nickel compound and a polyamide resin therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of the EVOH resin, adding a nickel compound and a polyamide resin to a homogeneous solution (water / alcohol solution, etc.) of ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0344] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound and a polyamide resin, thereby incorporating the nickel compound and polyamide resin into the EVOH resin (A), and then drying.

[0345] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0346] In the impregnation method described above, the content ratio of nickel element (B) can be controlled by the concentration of nickel element (B) and polyamide resin in the aqueous solution into which the EVOH resin is immersed, as well as the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0347] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0348] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0349] The resin composition (6) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (6), and it is preferable that the pellet consists only of the resin composition (6). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0350] The water content of the resin composition (6) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0351] The moisture content of this resin composition (6) is measured and calculated by the following method. The pre-drying mass (W1) of this resin composition (6) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and the mass (W2) after cooling in a desiccator for 30 minutes is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0352] Furthermore, if the resin composition (6) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (6). The lower limit is usually 0% by mass.

[0353] Furthermore, the larger the ratio of color number "1621" (R: 104, G: 88, B: 88) to color number "1604" (R: 104, G: 72, B: 72) ("1621" / "1604") measured using the Visual Analyzer IRIS VA400 (Alpha mos) for this resin composition (6), the more effectively yellow coloration can be suppressed.

[0354] Furthermore, the ratio of color number "2184" (R: 136, G: 136, B: 136) to color number "1621" (R: 104, G: 88, B: 88) ("2184" / "1621") indicates that a larger ratio means that the darker the red tinting can be suppressed.

[0355] In other words, the larger the ratios of "1621" / "1604" and "2184" / "1621", the better the thermal stability of the resin composition (6). Brightness is represented by the sum of the maximum and minimum values ​​of the RGB values ​​divided by two. A higher brightness value indicates lighter coloring. A difference of 0.1 in the ratios is very large, as it results in a significant difference in yield during actual manufacturing.

[0356] The resin composition (6) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (6) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (6).

[0357] Examples of the molded articles include single-layer films molded from the resin composition, and multilayer structures having at least one layer made of the resin composition (6).

[0358] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (6)") has a layer containing the resin composition (6), and it is preferable that it has a layer consisting solely of the resin composition (6). The layer containing the resin composition (6) (hereinafter simply referred to as "the resin composition layer (6)") can be laminated with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin") to further impart strength, protect the resin composition layer (6) from the effects of moisture, and impart other functions.

[0359] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0360] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0361] The layer configuration of this multilayer structure (6) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (6) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (6) and contains a mixture of this resin composition (6) and a thermoplastic resin other than this resin composition (6), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (6) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, adhesive resin layers containing adhesive resin may be interposed between each layer as needed.

[0362] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the above-mentioned modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0363] In this multilayer structure (6), when an adhesive resin layer is used between the resin composition layer (6) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (6).

[0364] The above-mentioned base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0365] Lamination of the resin composition layer (6) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (6); melt-extrude lamination of the resin composition (6) onto a base resin layer; co-extrusion of the resin composition (6) and the base resin; dry lamination of the resin composition (6) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (6) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (6), and specifically, the co-extrusion method is preferred.

[0366] The multilayer structure (6) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0367] Furthermore, the multilayer structure (6) after the stretching treatment may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (6) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0368] When the stretched multilayer structure (6) is used as a shrink film, in order to impart heat shrinkability, the above heat fixing procedure can be omitted, and instead, for example, the stretched multilayer structure (6) can be cooled and fixed by applying cold air.

[0369] The thickness of the multilayer structure (6) (including the stretched version), and furthermore, the thickness of the resin composition layer (6), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, the type of base resin, the type of adhesive resin, the application and packaging form, the required physical properties, etc. However, the thickness of the multilayer structure (6) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (6) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0370] Furthermore, the ratio of the thickness of the resin composition layer (6) to the base resin layer in the multilayer structure (6) (resin composition layer (6) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the ratio of the thickness of the resin composition layer (6) to the adhesive resin layer in the multilayer structure (6) (resin composition layer (6) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0371] It is also possible to obtain cup- or tray-shaped molded bodies and food packaging using this multilayer structure (6). In that case, deep drawing is usually employed, specifically vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded bodies before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0372] Single-layer films molded from this resin composition (6), and containers and lids such as bags, cups, trays, tubes, and bottles made from this multilayer structure (6) are useful as packaging materials for various products, including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0373] <<Aspect 7>> The seventh aspect includes the following aspects <VII-1> to <VII-15>. <VII-1> A resin composition containing an EVOH resin (A) and a nickel element (B), wherein the EVOH resin (A) includes an EVOH resin (A-1) and an EVOH resin (A-2) with different ethylene structural unit content ratios, and the difference in ethylene structural unit content ratios between the EVOH resin (A-1) and the EVOH resin (A-2) is 4 mol% or more, and the content ratio of the nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm of the entire resin composition. <VII-2> The EVOH resin (A) is １４ Including C, and the above １４A resin composition according to <VII-1>, wherein the content of C is 10 ppm or more. <VII-3> A resin composition according to <VII-1> or <VII-2>, wherein the biobase of the EVOH resin (A) is 0.0001% or more and 100% or less. <VII-4> A resin composition according to any one of <VII-1> to <VII-3>, wherein the content of ethylene structural units in the EVOH resin (A) is 20 to 60 mol%. <VII-5> A resin composition according to any one of <VII-1> to <VII-4>, comprising at least an ethylene-vinyl alcohol copolymer (A-1) having a content of ethylene structural units of 20 to 34 mol%, and an ethylene-vinyl alcohol copolymer (A-2) having a content of ethylene structural units of 35 to 60 mol%. <VII-6> The resin composition according to <VII-5>, wherein the mass ratio (A-1 / A-2) of an ethylene-vinyl alcohol copolymer (A-1) having a content of ethylene structural units of 20 to 34 mol% to an ethylene-vinyl alcohol copolymer (A-2) having a content of ethylene structural units of 35 to 60 mol% is 95 / 5 to 30 / 70. <VII-7> The resin composition according to any one of <VII-1> to <VII-6>, wherein the content of nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm with respect to the entire resin composition. <VII-8> The resin composition according to any one of <VII-1> to <VII-7>, wherein the content of nickel element (B) is 0.0001 ppm or more and less than 0.30 ppm with respect to the entire resin composition. <VII-9> A molding material comprising the resin composition according to any one of <VII-1> to <VII-8>. <VII-10> The molding material according to <VII-9>, wherein the molding material is in the form of pellets. <VII-11> A multilayer structure having a layer containing the resin composition according to any one of <VII-1> to <VII-8>. <VII-12> A molded article containing the multilayer structure according to <VII-11>. <VII-13> A food packaging article containing the multilayer structure according to <VII-11>.<VII-14> A method for producing a resin composition according to any one of <VII-1> to <VII-8>, comprising the step of melt-mixing resin composition raw materials containing the ethylene-vinyl alcohol copolymer (A) and nickel element (B). <VII-15> A method for producing a multilayer structure according to <VII-11>, comprising the step of melt-molding a layer containing the resin composition.

[0374] The present invention will be described below based on examples of embodiments for carrying out the seventh aspect. However, the present invention is not limited to the embodiments described below.

[0375] <Resin Composition> A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition (7)") contains ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2) with different ethylene structural unit content ratios, and contains at least a portion of biomass-derived EVOH resin (A) and nickel element (B) with a difference of 4 mol% or more in the ethylene structural unit content ratio between ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2). The base resin of the resin composition (7) is EVOH resin (A), and the content ratio of EVOH resin (A) in the resin composition (7) is usually 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The components will be described below.

[0376] [EVOH resin (A)] The EVOH resin (A) used in this resin composition contains ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2) with different ethylene structural unit content ratios, and the difference in ethylene structural unit content ratios between ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2) is 4 mol% or more, and at least a portion of the EVOH resin (A) is biomass-derived.

[0377] The resin composition (7) must contain two or more EVOH resins with different ethylene structural unit content ratios. By including two or more EVOH resins with different ethylene structural unit content ratios, the EVOH resin with the lower ethylene structural unit content ratio contributes to excellent gas barrier properties, while the EVOH resin with the higher ethylene structural unit content ratio contributes to excellent moldability and mechanical properties. As a result, it is possible to achieve both excellent gas barrier properties, moldability, and mechanical properties in the resulting resin composition, multilayer structure, and molded article.

[0378] The polymerization of ethylene and vinyl ester monomers can be carried out using any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, and generally, solution polymerization using methanol as the solvent is used. The saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by known methods.

[0379] The EVOH resin produced in this manner mainly consists of ethylene-derived structural units and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain unsaponified.

[0380] The difference in the content ratio of ethylene structural units between EVOH resin (A-1) and EVOH resin (A-2) in the aforementioned EVOH resin (A) is 4 mol% or more, preferably 5 to 30 mol%, more preferably 6 to 25 mol%, and even more preferably 7 to 20 mol%. The aforementioned EVOH resin (A) preferably contains at least an ethylene-vinyl alcohol copolymer (A-1) with an ethylene structural unit content of 20 to 34 mol%, and an ethylene-vinyl alcohol copolymer (A-2) with an ethylene structural unit content of 35 to 60 mol%. When the difference in the content ratio of ethylene structural units is above the lower limit, uneven thickness and cracks tend to occur less likely during molding of multilayer containers, and when it is below the upper limit, gas barrier properties and appearance tend to be good.

[0381] The number of EVOH resins with different ethylene structural unit content ratios is usually 2 to 4 types, preferably 2 to 3 types, and particularly preferably 2 types. When the number of types falls within this range, productivity and economic efficiency tend to be good.

[0382] Furthermore, the number of EVOH resins containing different proportions of ethylene structural units can be determined from the number of peaks measured using a differential scanning calorimeter (DSC) as described below.

[0383] The difference in the content ratio of two or more types of ethylene structural units in the aforementioned EVOH resin (A) can be determined, for example, by measuring the melting peak temperature. That is, since the content ratio of ethylene structural units in EVOH resin generally correlates with the melting point of the EVOH resin, the content ratio of two or more types of ethylene structural units in EVOH resin (A) can be calculated by measuring the melting peak temperature of the EVOH resin. The melting peak temperature refers to the peak temperature measured when the temperature is raised from -50 to 230°C at 10°C / min using DSC, then lowered from 230 to -50°C at 10°C / min, and then raised again from -50 to 230°C at 10°C / min.

[0384] The difference in melting peak temperatures (the difference in melting points between EVOH resin (A1) and EVOH resin (A2)) of the EVOH resin (A) obtained using such DSC is usually 3°C or higher, preferably 3 to 40°C, more preferably 6 to 24°C, and particularly preferably 8 to 16°C. When this temperature difference is above the lower limit, a good balance between moldability and gas barrier properties tends to be maintained, and when it is below the upper limit, excellent processability and mutual compatibility tend to be achieved.

[0385] Furthermore, it is preferable from the viewpoint of gas barrier properties and container moldability that the ethylene structural unit content of the EVOH resin (A-2) is higher than the ethylene structural unit content of the EVOH resin (A-1).

[0386] Furthermore, from the viewpoint of gas barrier properties and container moldability, it is preferable that the EVOH resin (A-1) is the EVOH resin with the lowest ethylene structural unit content among the EVOH resins (A), and that the EVOH resin (A-2) is the EVOH resin with the highest ethylene structural unit content among the EVOH resins (A).

[0387] The ethylene content in the EVOH resin (A) can be controlled by the pressure of the ethylene during copolymerization of the vinyl ester monomer and ethylene, and is preferably 20 to 60 mol%, more preferably 23 to 55 mol%, and even more preferably 25 to 50 mol%. When the ethylene content is below the upper limit, it tends to have excellent gas barrier properties, and when it is above the lower limit, it tends to have good gas barrier properties and melt moldability under high humidity.

[0388] The ethylene structural unit content of the EVOH resin (A-1) is typically 20 to 34 mol%, preferably 22 to 32 mol%, and more preferably 24 to 30 mol%. When the ethylene structural unit content is above the lower limit, it tends to have excellent secondary processability and flexibility, and when it is below the upper limit, it tends to have good gas barrier properties.

[0389] The ethylene structural unit content of the EVOH resin (A-2) is typically 35 to 60 mol%, preferably 38 to 55 mol%, and more preferably 40 to 51 mol%. When the ethylene structural unit content is above the lower limit, it tends to have excellent secondary processability and flexibility, and when it is below the upper limit, it tends to have good gas barrier properties.

[0390] As the vinyl ester monomer, vinyl acetate is typically used due to its market availability and efficient impurity removal during manufacturing. Other vinyl ester monomers besides vinyl acetate include, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Typically, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms can be used. These can be used individually or in combination of two or more.

[0391] Furthermore, the EVOH resin may also contain structural units derived from the following comonomers, within a range that does not impair the effects of the present invention (for example, 10 mol% or less of the EVOH resin).The aforementioned comonomers include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 3-buten-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2-diol, and their esterified and acylated derivatives; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy Hydroxyalkylvinylidene diacetates such as -2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydride) phthalic acid, (anhydride) maleic acid, (anhydride) itaconic acid, or their salts or mono or dialkyl esters with alkyl groups having 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide with alkyl groups having 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or their salts, acrylamidopropyldimethylamine or its salts or its quaternary salts, etc. Acrylamides; methacrylamide, N-alkylmethacrylamide with 1 to 18 carbon atoms in the alkyl group, N,N-dimethylmethacrylamide, 2-methacrylamidepropanesulfonic acid or its salts, methacrylamidopropyldimethylamine or its salts or its quaternary salts, etc.; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc.; vinyl cyanides such as acrylonitrile, methacrylnitrile, etc.; alkyl vinyl ethers with 1 to 18 carbon atoms in the alkyl group, hydr Examples include vinyl ethers such as roxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl halogenated compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halogenated compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These can be used individually or in combination of two or more types.

[0392] In particular, EVOH resins copolymerized with hydroxyl group-containing α-olefins, i.e., EVOH resins having primary hydroxyl groups in the side chains, are preferred in that they maintain gas barrier properties while exhibiting good secondary moldability, and among these, EVOH resins having a 1,2-diol structure in the side chains are preferred. When an EVOH resin has primary hydroxyl groups in the side chains, the content of structural units derived from monomers having such primary hydroxyl groups is usually 0.1 to 20 mol%, preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol%.

[0393] Furthermore, the EVOH resin used in this resin composition (7) may be a "post-modified" resin such as urethane, acetal, cyanoethylated, or oxyalkyleneated.

[0394] In this specification, the content ratio of ethylene structural units in EVOH resin is normally １ It is measured by 1H-NMR measurement. For example, １ 1H-NMR measurement was used, with DMSO-d as the measurement solvent. ６ A measurement method is used that employs a device and sets the measurement temperature to 50°C.

[0395] Furthermore, the degree of saponification of the vinyl ester component in EVOH resin (A) can be controlled by the amount, temperature, and time of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used to saponify the ethylene-vinyl ester copolymer, and is typically 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 99 to 100 mol%. If the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance, etc. tend to decrease.

[0396] The degree of saponification of the EVOH resin (A-1) is typically 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%, and particularly preferably 99.5 to 100 mol%. Having a degree of saponification within this range tends to result in good gas barrier properties, thermal stability, moisture resistance, etc.

[0397] The degree of saponification of the EVOH resin (A-2) is typically 90 to 99.7 mol%, preferably 93 to 99.5 mol%, and more preferably 95 to 99 mol%. When the degree of saponification is above the lower limit, gas barrier properties, thermal stability, and moisture resistance tend to be good, while when it is below the upper limit, secondary processability and flexibility tend to be good.

[0398] In this specification, the degree of saponification of EVOH resin is normally １ It is measured by 1H-NMR measurement. For example, １ A measurement method is used that employs 1H-NMR measurement, using DMSO-d6 as the measurement solvent and a measurement temperature of 50°C.

[0399] Furthermore, the melt flow rate (MFR) (210°C, load 2160g) of the EVOH resin (A) is typically 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, more preferably 2 to 35 g / 10 min, and even more preferably 3 to 25 g / 10 min. When the MFR is below the upper limit, the film-forming properties tend to be excellent, and when it is above the lower limit, the viscosity does not become too high, and the melt extrudeability tends to be good. The MFR is an indicator of the degree of polymerization of the EVOH resin and can be adjusted by the amount of polymerization initiator and solvent used when copolymerizing ethylene and vinyl ester monomer.

[0400] The melt flow rate (MFR) (210°C, 2160g load) of the EVOH resin (A-1) is typically 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 10 g / 10 min. When the MFR is below the upper limit, the mechanical strength of the molded product tends to be excellent, and when it is above the lower limit, the extrudeability tends to be good.

[0401] The melt flow rate (MFR) (210°C, 2160g load) of the EVOH resin (A-2) is typically 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and particularly preferably 3 to 30 g / 10 min. When the MFR is below the upper limit, the mechanical strength of the molded product tends to be excellent, and when it is above the lower limit, the extrudeability tends to be good.

[0402] Furthermore, when combining EVOH resin (A-1) and EVOH resin (A-2), it is preferable to adjust the molecular weight of each EVOH resin so that the difference in MFR (ΔMFR) (210°C, 2160g load) is 5g / 10min or less, and more preferably 1.5g / 10min or less, so that the resin flowability during melt molding is similar.

[0403] Furthermore, the density of EVOH resin (A) is 0.8 to 2.55 g / cm³ for both EVOH resin (A-1) and EVOH resin (A-2). 3 It is preferable that the density of the EVOH resin (A) is within the above range, which tends to enable stable extrusion molding. In this specification, density can be measured according to JIS Z8807.

[0404] The content of the EVOH resin (A-1) is preferably 10 to 99% by mass, more preferably 20 to 95% by mass, even more preferably 30 to 90% by mass, and particularly preferably 40 to 90% by mass, relative to the resin composition (7). When the content of the EVOH resin (A-1) is above the lower limit, the gas barrier properties tend to be excellent, and when it is below the upper limit, the thickness variation and cracks tend to be less likely to occur during the molding of multilayer containers.

[0405] The content of the EVOH resin (A-2) is preferably 1 to 90% by mass, more preferably 5 to 80% by mass, even more preferably 10 to 70% by mass, and particularly preferably 20 to 70% by mass, relative to the resin composition (7). When the content of the EVOH resin (A2) is above the lower limit, the gas barrier properties tend to be excellent, and when it is below the upper limit, the thickness variation and cracks tend to be less likely to occur during the molding of multilayer containers.

[0406] Furthermore, the mass ratio (A-1 / A-2) of the EVOH resin (A-1) to the EVOH resin (A-2) is preferably 95 / 5 to 30 / 70, more preferably 90 / 10 to 30 / 70, even more preferably 85 / 15 to 40 / 60, and particularly preferably 85 / 15 to 50 / 50.

[0407] Furthermore, the EVOH resin (A) is derived from biomass in at least a portion of its composition. The statement that the EVOH resin (A) is derived from biomass in at least a portion of its ethylene structural units, vinyl alcohol structural units, and vinyl ester structural units is derived from biomass.

[0408] The aforementioned EVOH resin (A), which is at least partly derived from biomass, is a water-insoluble thermoplastic resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and vinyl ester, at least partly derived from biomass.

[0409] The biomass origin of the ethylene and / or vinyl esters used as raw materials can be confirmed by measuring the biobase. The biobase is an index representing the proportion of biomass-derived raw materials, and in this specification, it refers to radiocarbon dating using an accelerator mass spectrometer (AMS). １４ This is the bio-based carbon content determined by measuring the concentration of C (which may hereafter be referred to as "carbon-14"). Specifically, the bio-based degree can be measured according to the method described in ASTM D6866-18. In other words, if the bio-based degree of EVOH resin is greater than 0% and less than or equal to 100%, it can be said that the ethylene and / or vinyl ester used as raw materials contains biomass-derived material.

[0410] "Biomass" refers to organic resources derived from plants and animals, excluding those derived from fossil fuels (fossil resources). From a cost and environmental perspective, it is preferable for biomass to be organic resources derived from plants, i.e., plant-based raw materials.

[0411] Biomass-derived ethylene can be produced, for example, by purifying bioethanol from biomass raw materials and carrying out a dehydration reaction. Biomass-derived vinyl esters can be produced, for example, by a common industrial method of reacting biomass-derived ethylene with acetic acid and oxygen molecules using a palladium catalyst.

[0412] Examples of biomass raw materials include waste materials, underutilized materials, and resource crops. These include cellulosic crops (pulp, kenaf, wheat straw, rice straw, waste paper, papermaking residue, etc.), wood, charcoal, compost, natural rubber, cotton, sugarcane, okara (soybean pulp), oils and fats (rapeseed oil, cottonseed oil, soybean oil, coconut oil, castor oil, etc.), carbohydrate crops (corn, potatoes, wheat, rice, rice hulls, rice bran, old rice, cassava, sago palm, etc.), bagasse, buckwheat, soybeans, essential oils (pine root oil, orange oil, eucalyptus oil, etc.), pulp black liquor, and vegetable oil cake. These can be used individually or in combination of two or more.

[0413] Methods for producing bioethanol include, for example, pre-treating biomass raw materials as needed (pressurized hot water treatment, acid treatment, alkali treatment, saccharification treatment using saccharifying enzymes), then fermenting them with yeast to produce bioethanol, and finally purifying the bioethanol through distillation and dehydration steps. When saccharification is performed during bioethanol production, sequential saccharification and fermentation, in which saccharification and fermentation are carried out in stages, or parallel saccharification and fermentation, in which saccharification and fermentation are carried out simultaneously, may be used. However, from the viewpoint of production efficiency, it is preferable to produce bioethanol by parallel saccharification and fermentation.

[0414] The proportion of biomass-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is usually 0.001 to 100 mol%, preferably 5 to 98 mol%, more preferably 15 to 97 mol%, even more preferably 25 to 96 mol%, and particularly preferably 35 to 95 mol%, although the total ethylene structural units may be biomass-derived. The proportion of fossil fuel-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is usually 99.999 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, even more preferably 75 mol% or less, and particularly preferably 65 mol% or less. The lower limit is 0 mol%, for example, 0 to 99.999 mol%. Fossil fuel-derived ethylene structural units may not be included in the total ethylene structural units. When the proportion of biomass-derived ethylene structural units in the total ethylene structural units constituting the EVOH resin (A) is high, the bio-based nature of the composition increases, and there is a tendency to reduce the environmental burden. Furthermore, if the EVOH resin (A) contains biomass-derived vinyl ester structural units and / or vinyl alcohol structural units, the proportion of biomass-derived ethylene structural units in the total ethylene structural units may be 0.

[0415] Examples of biomass-derived vinyl esters include vinyl esters produced using biomass-derived ethylene. Specifically, examples include vinyl acetate, in which the carbon in the vinyl group portion is derived from biomass.

[0416] EVOH resin (A), which is at least partially derived from biomass, is obtained by saponifying a copolymer of ethylene and vinyl ester, which is at least partially derived from biomass. Any known polymerization method can be used for copolymerization, such as solution polymerization, suspension polymerization, emulsion polymerization, etc.

[0417] The proportion of biomass-derived vinyl alcohol structural units in the total vinyl alcohol structural units (vinyl ester structural units) constituting the EVOH resin (A) is usually 0.001 to 100 mol%, preferably 5 to 98 mol%, more preferably 15 to 97 mol%, even more preferably 25 to 96 mol%, and particularly preferably 35 to 95 mol%. The proportion of fossil fuel-derived vinyl alcohol structural units in the total vinyl alcohol structural units constituting the EVOH resin (A) is usually 99.999 mol% or less, preferably 95 mol% or less, more preferably 85 mol% or less, even more preferably 75 mol% or less, and particularly preferably 65 mol% or less. The lower limit is 0 mol%, for example, 0 to 99.999 mol%. Fossil fuel-derived vinyl alcohol structural units may not be included in the total vinyl alcohol structural units. When the proportion of biomass-derived vinyl alcohol structural units in the total vinyl alcohol structural units constituting the EVOH resin increases, the bio-based nature of the resin composition increases, and the environmental burden tends to be reduced.

[0418] Furthermore, if the EVOH resin (A) contains biomass-derived ethylene structural units, the ratio of the total biomass-derived vinyl ester structural units and biomass-derived vinyl alcohol structural units to the total vinyl ester structural units and vinyl alcohol structural units may be 0.

[0419] The biomass origin of the EVOH resin (A) can be confirmed by the presence of "carbon 14" in the resin composition. "Carbon 14" is present in biomass-derived EVOH resins, but its presence cannot be confirmed in petroleum-derived EVOH resins, and its presence can be confirmed because it is a biomass-derived EVOH resin. In this specification, radiocarbon ( １４ By measuring the concentration of C), the carbon-14 content can be determined.

[0420] The carbon-14 content is usually 10 ppm or more, preferably 10 ppm to 500,000 ppm, more preferably 100 ppm to 100,000 ppm, even more preferably 500 ppm to 50,000 ppm, particularly preferably 600 ppm to 40,000 ppm, and most preferably 700 ppm to less than 30,000 ppm. When the carbon-14 content is above the lower limit, thermal stability is good, while when it is below the upper limit, it tends to have excellent long-run performance.

[0421] Furthermore, EVOH resins are known to have issues with thermal stability, and it is speculated that the main cause of thermal decomposition is the polyene structure formed in the main chain of the EVOH resin by a dehydration reaction starting from hydroxyl groups. In this resin composition, by using biomass-derived EVOH resin, it is speculated that the thermal decomposition rate of the EVOH resin itself will decrease and the thermal stability will improve due to the primary isotope effect of carbon-14 (increase in bond energy).

[0422] The bio-based content of the EVOH resin (A) is preferably 0.001% to 100%, more preferably 0.01% to 10%, even more preferably 0.05% to 5%, and particularly preferably 0.07% to less than 3%.

[0423] Furthermore, either the EVOH resin (A-1) or the EVOH resin (A-2) may be a biomass-derived EVOH resin, but it is preferable that the EVOH resin (A-1) and / or the EVOH resin (A-2) are biomass-derived EVOH resins, and it is preferable that the EVOH resin (A-1) is a biomass-derived EVOH resin.

[0424] [Nickel Element (B)] This resin composition (7) contains nickel element (B). The content of nickel element (B) is 0.0001 ppm or more and less than 1.00 ppm relative to the entire resin composition (7), preferably 0.0001 ppm or more and less than 0.50 ppm, more preferably 0.0001 ppm or more and less than 0.30 ppm, even more preferably 0.0005 ppm or more and 0.28 ppm or less, and particularly preferably 0.0007 ppm or more and 0.25 ppm or less. When the content of nickel element (B) is below the upper limit, thermal decomposition of this resin composition (7) is less likely to occur and it tends to be less prone to discoloration, and when it is above the lower limit, it tends to have an excellent effect in suppressing thermal degradation.

[0425] Furthermore, the content ratio of the nickel element (B) in the resin composition (7) can be determined, for example, by heating and ashing the resin composition and treating it with hydrochloric acid or the like to obtain a solution, adding pure water to the solution to obtain a fixed volume, using this as a test solution, and measuring it with an atomic absorption spectrophotometer.

[0426] The nickel element (B) used in this resin composition (7) can be included in the resin composition as a nickel compound containing it. As the nickel compound, the same nickel compound as described in the first embodiment above can be used.

[0427] It is generally known that EVOH resins undergo a color change after heating. This is presumed to be because double bond structures are formed in the main chain of the EVOH resin, and these structures then act as reaction initiation points, causing dehydration reactions and other processes, leading to the formation of polyene structures in the main chain of the EVOH resin.

[0428] In contrast, the present resin composition (7) contains a trace amount of nickel element (B), thereby suppressing discoloration due to thermal degradation of the EVOH resin. Normally, when a nickel compound is included in a resin composition, it is thought that the resin composition will become discolored due to nickel ions, so it is common technical knowledge for those skilled in the art to avoid using nickel compounds.

[0429] However, contrary to such common technical knowledge, the present invention has found that when a trace amount of elemental nickel (B) is contained and used, a resin composition with suppressed color change due to thermal degradation can be obtained.

[0430] That is, nickel is stable as a divalent ion. It is presumed that even in a trace amount, nickel coordinates to the double bonds in the main chain of the EVOH resin as described above, stabilizes the resin by forming chelates or the like, and thereby suppresses the formation of polyene structures. On the other hand, when the amount of the nickel compound is not more than the upper limit, it is considered that nickel can prevent thermal decomposition of the EVOH resin and consequent coloration. Furthermore, since nickel has high ionization energy among metals, it is presumed that nickel is less likely to desorb after coordinating to the double bonds in the main chain of the EVOH resin, and can easily maintain a stabilized state for a relatively long time, thus exerting the effect.

[0431] [Other thermoplastic resins] The present resin composition (7) may contain a thermoplastic resin other than EVOH resin within a range that does not impair the effect of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less based on the total mass of the present resin composition (7), and the lower limit is usually 0% by mass). As the other thermoplastic resins, known thermoplastic resins can be used, and examples thereof include polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, and chlorinated polypropylene. These can be used alone or in combination of two or more thereof.

[0432] [Other Compounding Agents] The present resin composition (7) may contain compounding agents generally formulated into EVOH resins (excluding nickel compounds) within a range that does not impair the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less of the present resin composition (7), and the lower limit is usually 0% by mass). Examples of the compounding agents include inorganic double salts, plasticizers (for example, aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and hexanediol), oxygen absorbers [for example, inorganic oxygen absorbers such as aluminum powder and potassium sulfite; polymer oxygen absorbers including ascorbic acid, further fatty acid esters and metal salts thereof, gallic acid, polyhydric phenols such as hydroxyl group-containing phenol-aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals other than nickel (for example, combinations of polypropylene and cobalt), blends of carbon-carbon unsaturated bond-containing resins and transition metals other than nickel (for example, combinations of polybutadiene and cobalt), photooxidatively degradable resins (for example, polyketones), anthraquinone polymers (for example, polyvinyl anthraquinone), and those obtained by adding photoinitiators (such as benzophenone), antioxidants other than the foregoing, and deodorants (such as activated carbon) to these compounds], heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (excluding those used as lubricants), antibacterial agents, antiblocking agents, fillers (for example, inorganic fillers), and the like. These compounds may be used alone or in combination of two or more thereof.

[0433] [Method for Producing Resin Composition] The present resin composition (7) can be produced by mixing two or more types of EVOH resins (A) having different ethylene structural unit content ratios and a nickel compound by a known method, such as dry blending, melt mixing, solution mixing, impregnation, or the like. Among these, production is preferably carried out by including a step of melt-mixing a resin composition raw material containing the EVOH resin (A) and the nickel compound. These production methods may also be optionally combined with each other.

[0434] Examples of the dry blending method include (i) a method of dry blending pelletized EVOH resin (A) and nickel element (B) using a tumbler or the like.

[0435] Examples of the melt mixing method include (ii) a method of melting and kneading a dry blend obtained by dry blending two types of pelletized EVOH resin (A) and a nickel compound, and (iii) a method of melting and kneading by adding a nickel compound to two types of EVOH resin (A) in a molten state.

[0436] Examples of the solution mixing method include (iv) preparing a solution using two commercially available EVOH resins (A), blending a nickel compound therein, solidifying and molding, and then separating the solid and liquid by known means and drying, and (v) during the manufacturing process of the two EVOH resins, adding a nickel compound to a homogeneous solution (water / alcohol solution, etc.) of the ethylene-vinyl ester copolymer solution or EVOH resin (A) before saponification, solidifying and molding, and then separating the solid and liquid by known means and drying.

[0437] Examples of the impregnation method include (vi) a method in which pelletized EVOH resin (A) is brought into contact with an aqueous solution containing a nickel compound, the nickel compound is incorporated into the EVOH resin (A), and then dried.

[0438] As the aqueous solution containing the nickel compound, an aqueous solution of the nickel compound or a solution obtained by immersing the nickel compound in water containing various chemicals to elute nickel ions can be used.

[0439] In the impregnation method described above, the content ratio of nickel element (B) can be controlled by the concentration of nickel element (B) in the aqueous solution into which the EVOH resin is immersed, as well as the immersion temperature and immersion time. The immersion temperature and immersion time are usually 0.5 to 48 hours, preferably 1 to 36 hours, and the immersion temperature is usually 10 to 40°C, preferably 20 to 35°C.

[0440] Various drying methods can be used in each of the above manufacturing methods, including static drying and fluidized bed drying. These methods can also be combined.

[0441] As described above, in this embodiment, it is possible to combine the different methods described above. Among them, the melt mixing method is preferred in that it yields a resin composition with greater productivity and more pronounced effects of the present invention, and method (ii) is particularly preferred. Furthermore, when using the other thermoplastic resins and other compounding agents, they may be compounded by conventional methods according to the above manufacturing method.

[0442] The resin composition (7) is suitably used as a molding material containing it. The shape of the molding material is arbitrary, but a pellet shape is preferred because it is easier to obtain the effects of the present invention. The pellet contains the resin composition (7), and it is preferable that the pellet consists only of the resin composition (7). The shape of the pellet may be spherical, oval, cylindrical, cubic, or rectangular, but it is usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, in the case of an oval shape, the short diameter is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20 mm, more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the base 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. It is also preferable that the shape and size of the pelletized EVOH resin used in each of the above manufacturing methods are similar.

[0443] The water content of the resin composition (7) is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and more preferably 0.1 to 0.3% by mass.

[0444] The moisture content of this resin composition (7) is measured and calculated by the following method. The pre-drying mass (W1) of this resin composition (7) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and the mass (W2) after cooling in a desiccator for 30 minutes is weighed and calculated using the following formula: Moisture content (mass%) = [(W1 - W2) / W1] × 100

[0445] Furthermore, if the resin composition (7) is in the form of pellets, it is also preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of lubricants include higher fatty acids having 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (methyl esters, isopropyl esters, butyl esters, octyl esters, etc. of higher fatty acids), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylenebis-oleic acid amide, ethylenebis-erucic acid amide, ethylenebis-lauric acid amide, etc.), low molecular weight polyolefins (e.g., low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols having 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. The content of such lubricants is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition (7). The lower limit is usually 0% by mass.

[0446] Furthermore, the ratio of color number "1927" (R: 120, G: 136, B: 120) to color number "1877" (R: 120, G: 88, B: 88) in the resin composition (7), measured using the visual analyzer IRIS VA400 (manufactured by Alpha mos), is usually greater than 3.4, preferably 3.45 or higher, and more preferably 3.5 or higher. The larger the ratio, the better the thermal stability tends to be. A difference of 0.1 in the ratio appears as a large difference in yield in actual manufacturing, indicating that the difference is very significant.

[0447] The resin composition (7) obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when provided as a material for melt molding. The resin composition (7) also includes resin compositions obtained by mixing resins other than the EVOH resin used in the resin composition (7).

[0448] Examples of the molded product include a single-layer film molded from the resin composition (7), and a multilayer structure having at least one layer made of the resin composition (7).

[0449] <Multilayer Structure> A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure (7)") has a layer containing the resin composition (7), and it is preferable that it has a layer consisting solely of the resin composition (7). The layer containing the resin composition (7) (hereinafter simply referred to as "the resin composition layer (7)") can be further strengthened, protected from the effects of moisture, or given other functions by laminating it with another substrate whose main component is a thermoplastic resin other than the resin composition (hereinafter, the resin used for the substrate may be abbreviated as "substrate resin").

[0450] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure as the main chain and / or side chains), or these polyolefins may be modified with unsaturated carboxylic acids or their esters. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins graft-modified with tel, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Note that linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to describe types of polyethylene.

[0451] Of these, hydrophobic resins such as polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferably are polyethylene resins, polypropylene resins, polycyclic olefin resins, and polyolefin resins such as unsaturated carboxylic acid-modified polyolefin resins.

[0452] The layer configuration of this multilayer structure (7) can be any combination, such as a / b, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc., when the resin composition layers (7) are a (a1, a2, ...) and the base resin layers are b (b1, b2, ...). Furthermore, when the recycled layer R is obtained by remelting edges and defective products generated during the manufacturing process of this multilayer structure (7) and contains a mixture of this resin composition (7) and a thermoplastic resin other than this resin composition (7), it is also possible to have a configuration such as b / R / a, b / R / a / b, b / R / a / R / b, b / R / a / R / a / R / b, b / R / a / R / a / R / b, etc. The total number of layers in this multilayer structure (7) is usually 2 to 15, preferably 3 to 10. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between each layer as needed.

[0453] As the adhesive resin, any known resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "b". Typical examples include modified polyolefin polymers containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the modified polyolefin polymers containing carboxyl groups include 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-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0454] In this multilayer structure (7), when an adhesive resin layer is used between the resin composition layer (7) and the base resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the resin composition layer (7).

[0455] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., in amounts that do not impede the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, relative to the total resin). These can be used individually or in combination of two or more.

[0456] Lamination of the resin composition layer (7) and the base resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. For example, methods include melt-extrude lamination of the base resin onto a film, sheet, etc., of the resin composition (7); melt-extrude lamination of the resin composition (7) onto a base resin layer; co-extrusion of the resin composition (7) and the base resin; dry lamination of the resin composition (7) (layer) and the base resin (layer) using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, and polyurethane compounds; and coating a solution of the resin composition (7) onto the base resin and then removing the solvent. Among these, considering cost and environmental viewpoints, it is preferable to manufacture by including a step of melt-molding the layer containing the resin composition layer (7), and specifically, the co-extrusion method is preferred.

[0457] The multilayer structure (7) may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can also be used. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be good, and when it is below the upper limit, a stable stretched state tends to be maintained.

[0458] Furthermore, the multilayer structure (7) after the stretching process may be heat-set for the purpose of providing dimensional stability. Heat-setting can be carried out by well-known means, for example, the stretched multilayer structure (7) is heat-treated at a temperature of 80 to 180°C, preferably 100 to 165°C, for about 2 to 600 seconds while maintaining tension.

[0459] When the stretched multilayer structure (7) is used as a shrink film, in order to impart heat shrinkability, the heat fixing described above may be omitted, and instead, a treatment such as applying cold air to the stretched multilayer structure (7) to cool and fix it may be performed.

[0460] The thickness of the multilayer structure (7) (including the stretched version), and furthermore, the thickness of the resin composition layer (7), base resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, the type of base resin, the type of adhesive resin, the application and packaging form, the required physical properties, etc. However, the thickness of the multilayer structure (7) (including the stretched version) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and more preferably 50 to 2000 μm. The resin composition layer (7) is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm; the base resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, and more preferably 20 to 1000 μm; and the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0461] Furthermore, the ratio of the thickness of the resin composition layer (7) to the base resin layer in the multilayer structure (7) (resin composition layer (7) / base resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Also, the ratio of the thickness of the resin composition layer (7) to the adhesive resin layer in the multilayer structure (7) (resin composition layer (7) / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0462] It is also possible to obtain cup- or tray-shaped molded articles and food packages using the present multilayer structure (7). In such cases, a draw forming method is usually employed, and specific examples thereof include vacuum forming, pressure forming, vacuum-pressure forming, and plug-assisted vacuum-pressure forming. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminate structures) from multilayer parisons (hollow tubular preforms before blowing), a blow molding method is employed. Specific examples thereof include extrusion blow molding (double-head type, mold moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretching blow molding (extrusion cold parison biaxial stretching blow molding, injection cold parison biaxial stretching blow molding, injection molding in-line biaxial stretching blow molding, etc.). If necessary, the obtained laminate can 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, splitting processing, and the like.

[0463] Single-layer films molded from the present resin composition (7), and containers and lid materials composed of bags, cups, trays, tubes, bottles and the like made of the present multilayer structure (7) are useful as packaging material containers for various products including general foods, seasonings such as mayonnaise and dressing, fermented foods such as miso, oil and fat foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0464] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as it does not exceed the gist of the present invention. In the examples, "parts" and "%" are based on mass.

[0465] <<First aspect>> <Example I-1> (Production of ethylene-vinyl acetate copolymer) A polymerization vessel was charged with 100 parts of vinyl acetate in which the carbon of the vinyl group is derived from biomass and 16 parts of methanol. After the inside of the system was once replaced with nitrogen gas, it was then replaced with ethylene, and ethylene was injected until the ethylene pressure reached 4.12 MPa. The temperature was raised to 67°C while stirring under ethylene pressure, and peroxyester was fed at a rate of 0.05 parts / hr for 4 hours, and the reaction was carried out for a total of 5.6 hours to obtain an ethylene-vinyl acetate copolymer.

[0466] (Production of EVOH resin) 100 parts of a methanol solution containing 50% of the above ethylene-vinyl acetate copolymer were mixed with 70 parts of a methanol solution containing 0.02 equivalents of sodium hydroxide relative to the remaining vinyl acetate groups in the copolymer, and a saponification reaction was carried out at 80°C for 80 minutes. Next, 100 parts of a methanol aqueous solution with a water content of 50% were added to the methanol solution of the EVOH resin under azeotropic conditions, and methanol was distilled off until the resin content in the methanol / aqueous solution of the EVOH resin reached 40%, obtaining a completely transparent methanol / water homogeneous solution of the EVOH resin. Then, the obtained methanol / aqueous solution of the EVOH resin was solidified into a thin plate shape and cut with a knife to obtain die-shaped pellets with sides of 3 mm. These obtained die-shaped pellets were washed for 30 minutes with 250 parts of treated water containing 5 parts of acetic acid per 100 parts of pellets, and this process was repeated twice. Next, the treated water was replaced with water, and 100 parts of the resulting die-shaped pellets were washed with 250 parts of water for 30 minutes. This process was repeated three times. Then, the resulting die-shaped pellets were dried at 118°C for 10 hours under a nitriding stream with an oxygen concentration of 0.5 volume% or less to obtain pellets of biomass-derived EVOH resin (a1) (ethylene structural unit content 32 mol%, degree of saponification 99.7 mol%, bio-basedness 33%).

[0467] The biomass-derived EVOH resin (a1) pellets were dry-blended with petroleum-derived EVOH resin (A'1) pellets (ethylene structural unit content 32 mol%, degree of saponification 99.6 mol%) and nickel(II) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a mixture. The bio-based content of the EVOH resin was 0.1%, and the nickel(II) oxide content was 0.001 ppm relative to the entire resin composition. The mixture was then kneaded in a twin-screw extruder (20 mmφ) equipped with a two-hole die, and the extruded strands were cooled and solidified by air cooling. Next, the solidified strands were cut with a pelletizer to obtain pellets of the resin composition. [Extrusion conditions] Extruder setting temperature (°C): C1 / C2 / C3 / C4 / C5 / C6 / H = 150 / 200 / 210 / 210 / 210 / 210 / 210

[0468] <Example I-2> Except that the amount of nickel(II) oxide added was changed so that the content of nickel(B) relative to the entire resin composition was 0.50 ppm, a pellet of the resin composition was obtained in the same manner as in Example I-1.

[0469] <Example I-3> A resin composition pellet was obtained in the same manner as in Example I-1, except that the bio-based content of the EVOH resin was changed to 0.05%.

[0470] <Comparative Example I-1> A resin composition pellet was obtained in the same manner as in Example I-1, except that nickel(II) oxide was not used.

[0471] <Comparative Example I-2> Except that the amount of nickel(II) oxide added was changed so that the content of nickel(B) relative to the entire resin composition was 1.0 ppm, a pellet of the resin composition was obtained in the same manner as in Example I-1.

[0472] <Comparative Example I-3> A pellet of the resin composition was obtained in the same manner as in Example I-1, except that EVOH resin (a1) was not used.

[0473] <Comparative Example I-4> Except that titanium(IV) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example I-1, and the amount of titanium(IV) oxide was changed to 0.001 ppm in terms of titanium element relative to the entire resin composition, a pellet of the resin composition was obtained in the same manner as in Example I-1.

[0474] <Comparative Example I-5> Except that iron(III) phosphate n hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example I-1, and the amount of iron(III) phosphate n hydrate was changed to 0.001 ppm in terms of iron element relative to the entire resin composition, a pellet of the resin composition was obtained in the same manner as in Example I-1.

[0475] The following thermal stability evaluations (color evaluations) were performed using the pellets of the resin compositions obtained in Examples I-1 to I-3 and Comparative Examples I-1 to I-5. The results are shown in Table I-1 below.

[0476] [Color Evaluation] Using pellets of the resin compositions obtained in Examples I-1 to I-3 and Comparative Examples I-1 to I-5 as samples, the ratio of color number "1604" (R: 104, G: 72, B: 72) to color number "1877" (R: 120, G: 88, B: 88) ("1604" / "1877") was evaluated using a visual analyzer IRIS VA400 (Alpha mos). The smaller the ratio, the better the thermal stability tends to be.

[0477]

[0478] From Table I-1 above, the resin compositions of Examples I-1 to I-3, which contain a specific amount of nickel element in an EVOH resin that is at least partially derived from biomass, exhibited superior thermal stability compared to the resin composition of Comparative Example I-1, which does not contain nickel element; the resin composition of Comparative Example I-2, which contains nickel element in an amount greater than a specific range; the resin composition of Comparative Example I-3, which does not contain biomass-derived EVOH resin; and the resin compositions of Comparative Examples I-4 and I-5, which contain metal elements other than nickel element. Furthermore, multilayer structures having layers containing the resin compositions of Examples I-1 to I-3 also exhibit superior thermal stability.

[0479] <<Second Embodiment>> <Example II-1> (Production of ethylene-vinyl acetate copolymer) 100 parts vinyl acetate, in which the carbon of the vinyl group portion is derived from biomass, and 16 parts methanol were charged into a polymerization tank. The system was first purged with nitride gas, and then purged with ethylene, and the mixture was injected under pressure until the ethylene pressure reached 4.12 MPa. Under ethylene pressure, the temperature was raised to 67°C while stirring, and the mixture was reacted for a total of 5.6 hours while charging peroxyester at a rate of 0.05 parts / hr for 4 hours to obtain an ethylene-vinyl acetate copolymer.

[0480] (Production of EVOH resin) 100 parts of a methanol solution containing 50% of the above ethylene-vinyl acetate copolymer were mixed with 70 parts of a methanol solution containing 0.02 equivalents of sodium hydroxide relative to the remaining vinyl acetate groups in the copolymer, and a saponification reaction was carried out at 80°C for 80 minutes. Next, 100 parts of a methanol aqueous solution with a water content of 50% were added to the methanol solution of the EVOH resin under azeotropic conditions, and methanol was distilled off until the resin content in the methanol / aqueous solution of the EVOH resin reached 40%, obtaining a completely transparent methanol / water homogeneous solution of the EVOH resin. Then, the obtained methanol / aqueous solution of the EVOH resin was solidified into a thin plate shape and cut with a knife to obtain die-shaped pellets with sides of 3 mm. These obtained die-shaped pellets were washed for 30 minutes with 250 parts of treated water containing 5 parts of acetic acid per 100 parts of pellets, and this process was repeated twice. Next, the treated water was replaced with water, and 100 parts of the resulting die-shaped pellets were washed with 250 parts of water for 30 minutes. This process was repeated three times. Then, the resulting die-shaped pellets were dried at 118°C for 10 hours under a nitriding stream with an oxygen concentration of 0.5 volume% or less to obtain pellets of biomass-derived EVOH resin (a1) (ethylene structural unit content 32 mol%, degree of saponification 99.7 mol%, bio-basedness 33%).

[0481] The biomass-derived EVOH resin (a1) pellets were dry-blended with petroleum-derived EVOH resin (A'1) pellets (ethylene structural unit content 32 mol%, degree of saponification 99.6 mol%), nickel(II) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and sodium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain a mixture. The bio-based content of the EVOH resin was 0.1%, the nickel(II) oxide content was 0.001 ppm relative to the total resin composition, and the alkali metal element content of the sodium acetate was 200 ppm relative to the total resin composition, so that the ratio of the content of nickel(II) to alkali metal elements in the resin composition [alkali metal element content / nickel(II) content] was 200,000. The mixture was then kneaded in a twin-screw extruder (20 mmφ) equipped with a two-hole die, and the extruded strands were cooled and solidified by air cooling. Next, the solidified strands were cut with a pelletizer to obtain pellets of the resin composition. [Extrusion conditions] Extruder set temperature (°C): C1 / C2 / C3 / C4 / C5 / C6 / H = 150 / 200 / 210 / 210 / 210 / 210 / 210

[0482] <Example II-2> Except that the amount of sodium acetate added was changed in Example II-1 so that the content of alkali metal elements relative to the entire resin composition was 400 ppm, and the ratio of the content of nickel element (B) to alkali metal elements in the resin composition [content of alkali metal elements / content of nickel element (B)] was 400,000, a pellet of the resin composition was obtained in the same manner as in Example II-1.

[0483] <Example II-3> Except that, in Example II-1, the amount of nickel(II) oxide added was changed so that the content of nickel(B) relative to the entire resin composition was 0.1 ppm, the amount of sodium acetate added was changed so that the content of alkali metal elements relative to the entire resin composition was 200 ppm, and the ratio of the content of nickel(B) relative to alkali metal elements in the resin composition [content of alkali metal elements / content of nickel(B)] was 2000, a pellet of the resin composition was obtained in the same manner as in Example II-1.

[0484] <Comparative Example II-1> Except that, in the same manner as in Example II-1, the amount of nickel(II) oxide added was changed so that the content of nickel(B) relative to the entire resin composition was 2 ppm, the amount of sodium acetate added was changed so that the content of alkali metal elements was 200 ppm, and the ratio of the content of nickel(B) to alkali metal elements in the resin composition [content of alkali metal elements / content of nickel(B)] was 100, a pellet of the resin composition was obtained.

[0485] <Comparative Example II-2> Except that the content of alkali metal elements in the total resin composition was changed to 700 ppm in Example II-1, and the ratio of the content of nickel element (B) to alkali metal elements in the resin composition [content of alkali metal elements / content of nickel element (B)] was set to 700,000, pellets of the resin composition were obtained in the same manner as in Example II-1.

[0486] <Comparative Example II-3> A pellet of the resin composition was obtained in the same manner as in Example II-1, except that EVOH resin (a1) was not used.

[0487] <Comparative Example II-4> Except that titanium(IV) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example II-1, and the amount of titanium(IV) oxide was changed to 0.001 ppm in terms of titanium element relative to the entire resin composition, a pellet of the resin composition was obtained in the same manner as in Example II-1.

[0488] <Comparative Example II-5> Except that iron(III) phosphate n hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example II-1, and the amount of iron(III) phosphate n hydrate was changed to 0.001 ppm in terms of iron element relative to the entire resin composition, a pellet of the resin composition was obtained in the same manner as in Example II-1.

[0489] The following thermal stability evaluation (color evaluation) was performed using the pellets of the resin compositions obtained in Examples II-1 to II-3 and Comparative Examples II-1 to II-5. The results are shown in Table II-1 below.

[0490] [Color Evaluation] Using pellets of the resin compositions obtained in Examples II-1 to II-3 and Comparative Examples II-1 to II-5 as samples, the ratio of color number "2201" (R: 136, G: 152, B: 152, Brightness: 144) to color number "1604" (R: 104, G: 72, B: 72, Brightness: 88) ("2201 / 1604") was evaluated using a visual analyzer IRIS VA400 (Alpha mos). The larger the ratio, the better the thermal stability tends to be.

[0491]

[0492] From Table II-1 above, the resin compositions of Examples II-1 to II-3, which contain nickel and alkali metal elements in specific ratios in combination with EVOH resin derived at least in part from biomass, exhibited superior thermal stability compared to the resin composition of Comparative Example II-1, where the content of nickel is above a specific range and the ratio of nickel and alkali metal elements is less than the specific ratio; the resin composition of Comparative Example II-2, where the ratio of nickel and alkali metal elements is greater than the specific ratio; the resin composition of Comparative Example II-3, which does not contain biomass-derived EVOH resin; and the resin compositions of Comparative Examples II-4 and II-5, which contain metal elements other than nickel. Furthermore, multilayer structures having layers containing the resin compositions of Examples II-1 to II-3 also exhibit superior thermal stability.

[0493] <<Third Embodiment>> <Example III-1> (Production of ethylene-vinyl acetate copolymer) 100 parts vinyl acetate, in which the carbon of the vinyl group portion is derived from biomass, and 16 parts methanol were charged into a polymerization tank. The system was first purged with nitride gas, and then purged with ethylene, and the mixture was injected under pressure until the ethylene pressure reached 4.12 MPa. Under ethylene pressure, the temperature was raised to 67°C while stirring, and the mixture was reacted for a total of 5.6 hours while charging peroxyester at a rate of 0.05 parts / hr for 4 hours to obtain an ethylene-vinyl acetate copolymer.

[0494] (Production of EVOH resin) 100 parts of a methanol solution containing 50% of the above ethylene-vinyl acetate copolymer were mixed with 70 parts of a methanol solution containing 0.02 equivalents of sodium hydroxide relative to the remaining vinyl acetate groups in the copolymer, and a saponification reaction was carried out at 80°C for 80 minutes. Next, 100 parts of a methanol aqueous solution with a water content of 50% were added to the methanol solution of the EVOH resin under azeotropic conditions, and methanol was distilled off until the resin content in the methanol / aqueous solution of the EVOH resin reached 40%, obtaining a completely transparent methanol / water homogeneous solution of the EVOH resin. Then, the obtained methanol / aqueous solution of the EVOH resin was solidified into a thin plate shape and cut with a knife to obtain die-shaped pellets with sides of 3 mm. These obtained die-shaped pellets were washed for 30 minutes with 250 parts of treated water containing 5 parts of acetic acid per 100 parts of pellets, and this process was repeated twice. Next, the treated water was replaced with water, and 100 parts of the resulting die-shaped pellets were washed with 250 parts of water for 30 minutes. This process was repeated three times. Then, the resulting die-shaped pellets were dried at 118°C for 10 hours under a nitriding stream with an oxygen concentration of 0.5 volume% or less to obtain pellets of biomass-derived EVOH resin (a1) (ethylene structural unit content 32 mol%, degree of saponification 99.7 mol%, bio-basedness 33%).

[0495] The biomass-derived EVOH resin (a1) pellets were dry-blended with petroleum-derived EVOH resin (A'1) pellets (ethylene structural unit content 32 mol%, degree of saponification 99.6 mol%), nickel(II) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and magnesium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) so that the biobase of the EVOH resin was 0.1%, the nickel(II) oxide content was 0.001 ppm relative to the total resin composition, the magnesium acetate content was 30 ppm relative to the total resin composition, and the ratio of nickel(II) to alkaline earth metal elements in the resin composition [alkaline earth metal element content / nickel(II) content] was 30,000 to obtain a mixture. The mixture was then kneaded in a twin-screw extruder (20 mmφ) equipped with a two-hole die, and the extruded strands were cooled and solidified by air cooling. Next, the solidified strands were cut with a pelletizer to obtain pellets of the resin composition. [Extrusion conditions] Extruder set temperature (°C): C1 / C2 / C3 / C4 / C5 / C6 / H = 150 / 200 / 210 / 210 / 210 / 210 / 210

[0496] <Example III-2> Except that the amount of magnesium acetate added was changed so that the content of alkaline earth metal elements relative to the entire resin composition was 40 ppm, and the ratio of the content of nickel element (B) to alkaline earth metal elements in the resin composition [content of alkaline earth metal elements / content of nickel element (B)] was 40,000, a pellet of the resin composition was obtained in the same manner as in Example III-1.

[0497] <Example III-3> A pellet of the resin composition was obtained in the same manner as in Example III-1, except that the bio-based content of the EVOH resin was changed to 0.05%.

[0498] <Comparative Example III-1> Except that the amount of nickel(II) oxide added was changed so that the content of nickel(B) relative to the entire resin composition was 2.0 ppm, the content of alkaline earth metal elements relative to the entire resin composition was changed to 100 ppm, and the ratio of the content of nickel(B) to alkaline earth metal elements in the resin composition [content of alkaline earth metal elements / content of nickel(B)] was 50, a pellet of the resin composition was obtained in the same manner as in Example III-1.

[0499] <Comparative Example III-2> Except that the content of alkaline earth metal elements in the entire resin composition was changed to 500 ppm in Example III-1, and the ratio of nickel element (B) to alkaline earth metal elements in the resin composition [content of alkaline earth metal elements / content of nickel element (B)] was set to 500,000, pellets of the resin composition were obtained in the same manner as in Example III-1.

[0500] <Comparative Example III-3> A pellet of the resin composition was obtained in the same manner as in Example III-1, except that EVOH resin (a1) was not used.

[0501] <Comparative Example III-4> Except that titanium(IV) oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example III-1, and the amount of titanium(IV) oxide was changed to 0.001 ppm in terms of titanium element relative to the entire resin composition, a pellet of the resin composition was obtained in the same manner as in Example III-1.

[0502] <Comparative Example III-5> Except that iron(III) n hydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of nickel(II) oxide in Example III-1, and the amount of iron(III) n hydrate relative to the entire resin composition was changed to 0.001 ppm in terms of iron element, a pellet of the resin composition was obtained in the same manner as in Example III-1.

[0503] The following thermal stability evaluation (color evaluation) was performed using the pellets of the resin compositions obtained from Examples III-1 to III-3 and Comparative Examples III-1 to III-5. The results are shown in Table III-1 below.

[0504] [Color Evaluation] Using pellets of the resin compositions obtained in Examples III-1 to III and Comparative Examples III-1 to III-5 as samples, the ratio of color number "1604" (R: 104, G: 72, B: 72) to color number "2168" (R: 136, G: 120, B: 136) ("1604" / "2168") was calculated using a visual analyzer IRIS VA400 (Alpha mos). A smaller ratio indicates better thermal stability.

[0505]

[0506] From Table III-1 above, the resin compositions of Examples III-1 to III-3, which contain nickel and alkaline earth metal elements in specific ratios in combination with EVOH resin that is at least partially derived from biomass, exhibited superior thermal stability compared to the resin composition of Comparative Example III-1, where the content of nickel is above a specific range and the ratio of nickel and alkaline earth metal elements is less than the specific ratio; the resin composition of Comparative Example III-2, where the ratio of nickel and alkaline earth metal elements is greater than the specific ratio; the resin composition of Comparative Example III-3, which does not contain biomass-derived EVOH resin; and the resin compositions of Comparative Examples III-4 and III-5, which contain metal elements other than nickel. Furthermore, multilayer structures having layers containing the resin compositions of Examples III-1 to III-3 also exhibit superior thermal stability.

[0507] <<Fourth Embodiment>> <Example IV-1> (Production of ethylene-vinyl acetate copolymer) 100 parts vinyl acetate and 16 parts methan...

Claims

1. A resin composition containing an ethylene-vinyl alcohol copolymer (A) and an element nickel (B), wherein at least a portion of the ethylene-vinyl alcohol copolymer (A) is derived from biomass, and the content of the element nickel (B) is 0.0001 ppm or more and less than 1.00 ppm relative to the entire resin composition.

2. The ethylene-vinyl alcohol copolymer (A) １４ Including C, and the above １４ The resin composition according to claim 1, wherein the content of C is 10 ppm or more.

3. The resin composition according to claim 1 or 2, wherein the bio-based content of the ethylene-vinyl alcohol copolymer (A) is 0.0001% or more and 100% or less.

4. The resin composition according to claim 1 or 2, wherein the content of ethylene structural units in the ethylene-vinyl alcohol copolymer (A) is 20 to 60 mol%.

5. The resin composition according to claim 1 or 2, wherein the resin composition contains at least one selected from the group consisting of alkali metal elements, alkaline earth metal elements, boron elements, and lubricants.

6. The resin composition according to claim 5, wherein the ratio of the content of nickel element (B) to the alkali metal element in the resin composition [content of alkali metal element / content of nickel element (B)] is 200 to 600,000.

7. The resin composition according to claim 5, wherein the ratio of the content of nickel element (B) to the content of alkaline earth metal element in the resin composition [content of alkaline earth metal element / content of nickel element (B)] is 100 to 300,000.

8. The resin composition according to claim 5, wherein the ratio of the content of nickel element (B) to the content of boron element in the resin composition [content of boron element / content of nickel element (B)] is 1,000 to 600,000.

9. The resin composition according to claim 5, wherein the ratio of the content of nickel element (B) to the lubricant in the resin composition [content of lubricant / content of nickel element (B)] is 200 to 600,000.

10. The resin composition according to claim 1 or 2, wherein the resin composition contains a polyamide resin, and the content of nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm with respect to the entire resin composition.

11. The resin composition according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer (A) comprises ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2) having different ethylene structural unit content ratios, and the difference in ethylene structural unit content ratios between ethylene-vinyl alcohol copolymer (A-1) and ethylene-vinyl alcohol copolymer (A-2) is 4 mol% or more, and the content ratio of nickel element (B) is 0.0001 ppm or more and less than 0.50 ppm with respect to the entire resin composition.

12. The resin composition according to claim 11, comprising at least an ethylene-vinyl alcohol copolymer (A-1) having a content of ethylene structural units of 20 to 34 mol%, and an ethylene-vinyl alcohol copolymer (A-2) having a content of ethylene structural units of 35 to 60 mol%.

13. The resin composition according to claim 11, wherein the content of nickel element (B) is 0.0001 ppm or more and less than 0.30 ppm with respect to the entire resin composition.

14. The resin composition according to claim 12, wherein the mass ratio (ethylene-vinyl alcohol copolymer (A-1) / ethylene-vinyl alcohol copolymer (A-2)) of ethylene-vinyl alcohol copolymer (A-2) having a content of ethylene structural units of 20 to 34 mol% to ethylene-vinyl alcohol copolymer (A-1) having a content of ethylene structural units of 35 to 60 mol% is 95 / 5 to 30 / 70.

15. A molding material comprising the resin composition according to claim 1 or 2.

16. The molding material according to claim 15, wherein the molding material is in the form of pellets.

17. A multilayer structure having a layer containing the resin composition according to claim 1 or 2.

18. A molded article comprising the multilayer structure described in claim 17.

19. A food packaging comprising the multilayer structure described in claim 17.

20. A method for producing the resin composition according to claim 1 or 2, comprising the step of melting and mixing resin composition raw materials containing the ethylene-vinyl alcohol copolymer (A) and nickel element (B).

21. A method for producing a multilayer structure according to claim 17, comprising the step of melt-molding a layer containing the resin composition.

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