Resin composition, molded body, sheet, film, regrind layer, multilayer structure, and method for producing multilayer structure and molded body

Abstract

Provided is a resin composition excellent in thermal stability.　Specifically, a resin composition comprising a carbon 14-containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C) is provided.

Description

Resin composition, molded article, sheet, film, regrind layer, multilayer structure, and method for producing multilayer structure and molded article

[0001] The present invention relates to a resin composition, and also to a molded article, sheet, film, regrind layer, multilayer structure, and method for producing the multilayer structure and molded article, each containing the resin composition.

[0002] Conventionally, ethylene-vinyl alcohol copolymers (hereinafter sometimes referred to as "EVOH resins") have been mainly used as food packaging materials due to their excellent gas barrier properties and transparency. Sheets, films, etc. used as food packaging materials can be produced using the EVOH resins alone, but they are often blended with other thermoplastic resins to improve physical properties, or multilayer structures in which layers made of polyolefin resins or the like are laminated to impart other functions.

[0003] For example, in order to improve the gas barrier properties of a molded body against oxygen and water vapor, a resin composition has been proposed in which a resin mainly composed of a polypropylene resin and an EVOH resin contains maleic acid-modified polypropylene as a compatibilizer (see Patent Document 1 below).

[0004] International Publication No. 2021 / 193318

[0005] According to the investigations of the present inventors, it has been found that although the resin composition disclosed in Patent Document 1 prevents a decrease in mechanical strength and prevents discoloration even when the recovered materials are reused as a resin composition, the thermal stability of the resin composition itself is still insufficient.

[0006] In view of this background, the present invention provides a resin composition having excellent thermal stability.

[0007] In view of the above circumstances, the present inventors have conducted extensive research and have found that a resin composition having excellent thermal stability can be obtained by using a (biomass-derived) polypropylene resin containing carbon-14 instead of a conventional petroleum-derived polypropylene resin.

[0008] That is, the present invention has the following aspects. [1] A resin composition containing a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C). [2] The resin composition according to [1], wherein the carbon-14 containing polypropylene resin (A) contains a bio-polypropylene resin. [3] The resin composition according to [1] or [2], wherein the resin composition excludes the following resin composition [α]. Resin composition [α] contains a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d block of Period 4 of the Long Form Periodic Table. [4] The resin composition according to any one of [1] to [3], wherein the ethylene-vinyl alcohol copolymer (B) contains a structural unit having a primary hydroxyl group in a side chain. [5] The resin composition according to any one of [1] to [3], wherein the ethylene-vinyl alcohol copolymer (B) contains an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, and wherein the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more. [6] The resin composition according to [5], wherein the resin composition at least contains the ethylene-vinyl alcohol copolymer (B1) having an ethylene structural unit content of 20 to 34 mol % and the ethylene-vinyl alcohol copolymer (B2) having an ethylene structural unit content of 35 to 60 mol %. [7] The resin composition according to any one of [1] to [3], further containing an ethylene-α-olefin copolymer (F). [8] The resin composition according to [7], wherein the content of the ethylene-α-olefin copolymer (F) is 0.01 mass% or more and 35 mass% or less with respect to the entire resin composition. [9] The resin composition according to any one of [1] to [8], wherein the polypropylene resin (A) containing 14 carbon atoms is a homopolypropylene.

[10] The resin composition according to any one of [1] to [9], wherein the carbon-14-containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having from 10 to 24 carbon atoms.

[11] The resin composition according to any one of [1] to

[10] , wherein the ethylene-vinyl alcohol copolymer (B) has an ethylene structural unit content of 20 to 60 mol%.

[12] The resin composition according to any one of [1] to

[11] , wherein the ethylene-vinyl alcohol copolymer (B) has an ethylene structural unit content of 0.01 to 15.0 mass% relative to the total resin composition.

[13] The resin composition according to any one of [1] to

[12] , wherein the carbon-14-containing polypropylene resin (A) has an ethylene structural unit content of from 10 to 99 mass% relative to the total resin composition.

[14] The resin composition according to any one of [1] to

[13] , wherein the acid-modified polyolefin resin (C) has an ethylene structural unit content of from 0.1 to 20 mass% relative to the total resin composition.

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

[14] .

[16] A film comprising the resin composition according to any one of [1] to

[14] .

[17] A regrind layer comprising the resin composition according to any one of [1] to

[14] .

[18] A multilayer structure comprising the regrind layer according to

[17] .

[19] The multilayer structure according to

[18] , further comprising a layer comprising a polyolefin resin.

[20] The multilayer structure according to

[18] , further comprising an adhesive resin layer.

[21] The multilayer structure according to

[18] , further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer.

[22] A molded article obtained by molding the multilayer structure according to

[18] .

[23] A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of [1] to

[14] .

[24] A method for producing a molded article, comprising a step of molding the multilayer structure according to

[18] .

[0009] The resin composition of the present invention has excellent thermal stability. Furthermore, molded articles, sheets, films, regrind layers, and multilayer structures containing the resin composition of the present invention also have excellent thermal stability.

[0010] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0011] As used herein, "x and / or y (x and y are any configuration)" refers to at least one of x and y, and can mean three things: x only, y only, or both x and y. As used herein, "X to Y" (X and Y are any numbers) means "X or more and Y or less," unless otherwise specified, and also encompasses "preferably more than X" or "preferably less than Y." As used herein, "X or more" (X is any number) or "Y or less" (Y is any number) also encompasses "preferably more than X" or "preferably less than Y." With regard to the numerical ranges described in stages herein, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described herein, the upper or lower limit of that numerical range can also be replaced with the values ​​shown in the examples. Furthermore, as used herein, the term "layer" also encompasses relatively thin layers such as "films," "tapes," and "sheets." In this specification, the term "main component" refers to the component that accounts for the largest proportion in the target, and typically accounts for preferably 50% by mass or more of the target, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and especially preferably 90% by mass or more, or even 100% by mass. The range of the content is, for example, 50 to 100% by mass.

[0012] A resin composition according to an embodiment of the present invention (hereinafter referred to as "the resin composition") contains a polypropylene resin (A) containing 14 carbon atoms, an EVOH resin (B), and an acid-modified polyolefin resin (C). From the viewpoint of thermal stability, the resin composition preferably does not contain the following resin composition [α]. Resin composition [α] contains a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block elements of Period 4 of the Long Form Periodic Table.

[0013] In addition, in the present resin composition, it is preferred that the EVOH resin (B) contains a structural unit having a primary hydroxyl group in a side chain (second embodiment), that the EVOH resin (B) contains EVOH resin (B1) and EVOH resin (B2) having different proportions of ethylene structural units, and that the difference in the content of ethylene structural units between the EVOH resin (B1) and the EVOH resin (B2) is 4 mol % or more (third embodiment), and that the resin composition further contains an ethylene-α-olefin copolymer (F) (fourth embodiment). Each embodiment will be described below.

[0014] <<First Aspect>> The first aspect includes the following aspects <I-1> to <I-19>. <I-1> A resin composition containing a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C). <I-2> The resin composition according to <I-1>, in which the carbon-14 containing polypropylene resin (A) includes a bio-polypropylene resin. <I-3> The resin composition according to <I-1> or <I-2>, in which the following resin composition [α] is excluded from the resin composition. Resin composition [α] includes a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) that is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d block of Period 4 of the Long Form Periodic Table. <I-4> The resin composition according to any one of <I-1> to <I-3>, wherein the carbon-14 containing polypropylene resin (A) is a homopolypropylene. <I-5> The resin composition according to any one of <I-1> to <I-4>, wherein the carbon-14 containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having from 10 to 24 carbon atoms. <I-6> The resin composition according to any one of <I-1> to <I-5>, wherein the ethylene-vinyl alcohol copolymer (B) contains 20 to 60 mol% of ethylene structural units. <I-7> The resin composition according to any one of <I-1> to <I-6>, wherein the ethylene-vinyl alcohol copolymer (B) contains 0.01 to 15.0 mass% of the total resin composition. <I-8> The resin composition according to any one of <I-1> to <I-7>, wherein the carbon-14 containing polypropylene resin (A) contains 10 to 99 mass% of the total resin composition. <I-9> The resin composition according to any one of <I-1> to <I-8>, wherein the content of the acid-modified polyolefin resin (C) is 0.1% by mass or more and 20% by mass or less, based on the total mass of the resin composition. <I-10> A sheet comprising the resin composition according to any one of <I-1> to <I-9>.<I-11> A film comprising the resin composition according to any one of <I-1> to <I-9>. <I-12> A regrind layer comprising the resin composition according to any one of <I-1> to <I-9>. <I-13> A multilayer structure comprising the regrind layer according to <I-12>. <I-14> The multilayer structure according to <I-13>, further comprising a layer comprising a polyolefin resin. <I-15> The multilayer structure according to <I-13>, further comprising an adhesive resin layer. <I-16> The multilayer structure according to <I-13>, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer. <I-17> A molded article obtained by molding the multilayer structure according to <I-13>. <I-18> A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of <I-1> to <I-9>. <I-19> A method for producing a molded article, comprising a step of molding the multilayer structure according to <I-13>.

[0015] The present invention will be described below based on examples of modes for carrying out the first aspect, although the present invention is not limited to the embodiments described below.

[0016] <Resin Composition (1)> A resin composition according to an embodiment of the present invention (hereinafter referred to as "the present resin composition (1)") contains a polypropylene resin (A) containing 14 carbon atoms, an EVOH resin (B), and an acid-modified polyolefin resin (C). From the viewpoint of thermal stability, the present resin composition (1) preferably does not contain the following resin composition [α]. Resin composition [α] contains a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d block of Period 4 of the Long Periodic Table. Each component will be described below.

[0017] <Carbon-14-containing polypropylene resin (A)> The carbon-14-containing polypropylene resin (A) used in the resin composition (1) refers to a polypropylene resin obtained by chemical or biological synthesis using renewable biomass resources as raw materials. Carbon-14-containing polypropylene resin (A) has the advantage that, even when incinerated, it does not increase the carbon dioxide concentration in the atmosphere due to the carbon-neutrality of biomass.

[0018] The carbon-14 containing polypropylene resin (A) is preferably a bio-polypropylene resin derived from biopropanol obtained from plant raw materials. That is, the carbon-14 containing polypropylene resin (A) is preferably a plant-derived polypropylene resin.

[0019] In addition, plant (biomass resource) derived polypropylene resin and petroleum derived polypropylene resin do not differ in physical properties such as molecular weight and mechanical properties. Therefore, to distinguish between them, the bio-based content is generally used. The bio-based content refers to the carbon content of petroleum derived polypropylene resin. 14 Since it does not contain radioactive carbon 14 (half-life 5730 years), 14 The concentration of carbon-14 is measured by accelerator mass spectrometry and used as an index of the content of plant-derived polypropylene resin. Therefore, if a film is made using plant-derived polypropylene resin, measuring the bio-based content of the film will result in a bio-based content that corresponds to the content of plant-derived polypropylene resin. That is, polypropylene resin (A) containing carbon-14 can detect radioactive carbon ( 14 C).

[0020] The biobased content can be determined, for example, by heating and stirring the resin composition in a water / methanol mixed solvent to dissolve the polypropylene resin, and then measuring the carbon-14 ( 14C) The content ratio can be determined by measuring the following method. The sample to be measured is burned to generate carbon dioxide, which is purified in a vacuum line and reduced with hydrogen using iron as a catalyst to generate graphite. Then, this graphite is analyzed using a tandem accelerator-based 14 Attach it to a dedicated C-AMS device (manufactured by NEC) 14 Counting C, 13 The concentration of C ( 13 C / 12 C), 14 The concentration of C ( 14 C / 12 C) is measured, and the carbon content of the sample is compared to that of the standard modern carbon. 14 The C concentration is calculated, and the biobased content is determined in accordance with ASTM D6866.

[0021] The carbon-14 content of the carbon-14-containing polypropylene resin (A) is not particularly limited, but is usually 1.0 × 10 -14 or more, 1.0 × 10 -13 The upper limit is usually 1.2 × 10 -12 The range of the carbon-14 content in the polypropylene resin (A) containing carbon-14 is usually 1.0 × 10 -14 1.2 x 10 -12 The following are examples.

[0022] The resin composition (1) contains a polypropylene resin (A) containing 14 carbon atoms in a resin composition containing an EVOH resin (B), and thus has superior thermal stability compared to resin compositions containing conventional petroleum-derived polypropylene resins.

[0023] The mechanism is thought to be as follows. It is known that petroleum-derived polypropylene resins are easily oxidized by heat, generating hydroperoxides and causing degradation reactions such as molecular weight reduction. One known method for suppressing such thermal degradation is to improve the thermal stability of polypropylene by adding antioxidants such as hindered phenols. However, because these antioxidants tend to interact with EVOH resins, the thermal stability improvement effect is not fully achieved. In particular, when added in large amounts, the antioxidant's anti-discoloration effect and mechanical properties tend to deteriorate. In such resin compositions containing polypropylene resin and EVOH resin as essential components, the use of a carbon-14-containing polypropylene resin (A) increases the bond energy due to the primary isotope effect. As a result, it is presumed that the decomposition of the carbon-14-containing polypropylene resin (A) itself is slowed, resulting in enhanced thermal stability. Furthermore, because thermal stability can be improved without affecting the EVOH resin (B), it is presumed that an excellent thermal stability improvement effect is achieved.

[0024] The carbon-14-containing polypropylene resin (A) used in the resin composition (1) typically has a biobased content of 1 to 99%, preferably 5 to 95%, more preferably 10 to 90%, even more preferably 20 to 80%, and particularly preferably 30 to 70%. By adjusting the biobased content of the carbon-14-containing polypropylene resin (A) to fall within the above range, a resin composition with even better thermal stability can be obtained.

[0025] The type of "polypropylene resin" in the carbon-14 containing polypropylene resin (A) is not particularly limited, and may be a homopolypropylene or a copolymer of propylene and a small amount of a comonomer. The copolymer may be in the form of a block copolymer or a random copolymer. For example, a copolymer consisting of propylene and less than 50% by mass of another α-olefin monomer, or a copolymer consisting of 3% or less by mass of a non-olefin monomer having a functional group may be used.

[0026] Examples of the other α-olefin monomers include ethylene, α-olefins having 4 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, and 3-methyl 1-butene, 4-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc. These may be used alone or in combination of two or more.

[0027] Examples of the non-olefin monomer include styrene monomers, diene monomers, cyclic monomers, oxygen atom-containing monomers, etc. These may be used alone or in combination of two or more.

[0028] Examples of the styrene monomer include styrene, 4-methylstyrene, and 4-dimethylaminostyrene.

[0029] Examples of the diene monomer include 1,3-butadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decatriene (DMDT), dicyclopentadiene, cyclohexadiene, and dicyclooctadiene.

[0030] Examples of the cyclic monomer include methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, and cyclopentene.

[0031] Examples of the oxygen atom-containing monomer include hexenol, hexenoic acid, and methyl octenoate.

[0032] The other α-olefin monomer and non-olefin monomer may be derived from renewable biomass resources or petroleum. When a renewable biomass resource is used as a raw material, the bio-based content of the final product can be further increased. When a petroleum-based raw material is used, a wide variety of petroleum-based raw materials are available, and by using these raw materials in production, the physical properties of the carbon-14-containing polypropylene resin (A) can be easily adjusted.

[0033] As described above, the polypropylene resin (A) containing 14 carbon atoms is obtained by homopolymerization of propylene or copolymerization of propylene with a comonomer, and the polymerization or copolymerization can be carried out in accordance with a conventional method using a metallocene catalyst or a Ziegler-Natta catalyst. Among these, the use of a metallocene catalyst is preferred.

[0034] The polypropylene resin (A) containing 14 carbon atoms may be used alone or in combination of two or more kinds. Among these, homopolypropylene derived from biopropylene, or ethylene-propylene block copolymer, ethylene-propylene random copolymer, or impact copolymer derived from biopropylene are preferred in terms of moldability, handleability, and thermal stability, and homopolypropylene is particularly preferred.

[0035] Furthermore, the carbon-14 containing polypropylene resin (A) may contain linear aliphatic hydrocarbons having a carbon number of 10 to 24. When the carbon-14 containing polypropylene resin (A) contains linear aliphatic hydrocarbons having a carbon number of 10 to 24, the content is typically 20% by mass or less, based on the entire carbon-14 containing polypropylene resin (A). The lower limit is 0% by mass. The range of such content is typically 0% by mass or more and 20% by mass or less. When the linear aliphatic hydrocarbons are equal to or less than the upper limit, the effects of the present invention tend to be more effectively obtained.

[0036] The melt flow rate (MFR) (230°C, 2160 g load) of the polypropylene resin (A) containing 14 carbon atoms is usually 0.1 to 100 g / 10 min, preferably 0.5 to 80 g / 10 min, more preferably 1 to 60 g / 10 min, even more preferably 1.5 to 40 g / 10 min, and particularly preferably 2 to 20 g / 10 min. When the MFR is equal to or less than the upper limit, the film-forming property tends to be excellent, and when the MFR is equal to or more than the lower limit, the viscosity does not become too high and the melt extrudability tends to be good.

[0037] Commercially available polypropylene resin (A) containing carbon 14 that is preferably used in this embodiment includes HP640J manufactured by LyondellBasell.

[0038] The content of the carbon-14 containing polypropylene resin (A) is typically 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total resin composition. The upper limit is typically 99% by mass, preferably 96% by mass. The range of such a content is typically 10% by mass or more and 99% by mass or less. By setting the content of the carbon-14 containing polypropylene resin (A) within the above range, a resin composition with better thermal stability can be obtained.

[0039] <EVOH Resin (B)> The EVOH resin (B) is a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is a water-insoluble thermoplastic resin.

[0040] The polymerization of ethylene and vinyl ester monomers can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, and solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method.

[0041] The EVOH resin (B) produced in this manner is mainly composed of structural units derived from ethylene and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain unsaponified.

[0042] Vinyl acetate is typically used as the vinyl ester monomer because of its commercial availability and the efficiency of impurity removal during production. Examples of vinyl ester monomers other than vinyl acetate include 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. Aliphatic vinyl esters having typically 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 alone or in combination of two or more types.

[0043] The content of ethylene structural units in the EVOH resin (B) can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene, and is usually 20 to 60 mol %, preferably 23 to 55 mol %, and more preferably 25 to 50 mol %. When the content is equal to or less than the upper limit, the resin tends to have excellent gas barrier properties, and when the content is equal to or more than the lower limit, the resin tends to have good gas barrier properties and melt moldability under high humidity. 1It is measured by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0044] The degree of saponification of the vinyl ester component in the EVOH resin (B) can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) used when saponifying the ethylene-vinyl ester copolymer, and is usually 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%. When the saponification degree is equal to or higher than the lower limit, the gas barrier property, thermal stability, moist heat resistance, etc. tend to be good. The degree of saponification of the EVOH resin (B) is usually 1 It is measured by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0045] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B) is typically 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, more preferably 2 to 25 g / 10 min, and even more preferably 3 to 10 g / 10 min. Having an MFR below the upper limit of the range tends to result in excellent film-forming properties, while having an MFR above the lower limit of the range tends to result in a resin with a viscosity that is not too high and good melt extrudability. The MFR is an indicator of the degree of polymerization of the EVOH resin and can be adjusted by adjusting the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene and vinyl ester monomers. In this specification, the MFR can be determined by measuring the flow rate of a sample through an orifice with a length of 8 mm and a diameter of 2.095 mm under conditions of 210°C and a load of 2160 g using an automatic melt flow rate tester (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0046] The density of the EVOH resin (B) is 0.8 to 2.55 g / cm 3When the density of the EVOH resin (B) is within the above range, stable extrusion molding tends to be possible. In this specification, the density can be measured in accordance with JIS Z8807.

[0047] The EVOH resin (B) may further contain structural units derived from the comonomers shown below within a range that does not impair the effects of the present invention (for example, 10 mol % or less of the EVOH resin (B)).Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxy group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation 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-dibutyryloxy-2-methylenepropane. -hydroxyalkylvinylidene diacetates such as 2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salt, acrylamidopropyldimethylamine or its acid salt or its quaternary salt, etc. Acrylamides; methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or an acid salt or a quaternary salt thereof, and other methacrylamido groups; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochlorides, etc. vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl 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 may be used alone or in combination of two or more.

[0048] Among these, hydroxy group-containing α-olefins are preferred, and 3-butene-1,2-diol, 5-hexene-1,2-diol, and 2-methylenepropane-1,3-diol are particularly preferred. When the hydroxy group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in the side chains. Such EVOH resins having primary hydroxyl groups in the side chains, particularly EVOH resins having a 1,2-diol structure in the side chains, are preferred in that they maintain gas barrier properties while exhibiting good secondary moldability.

[0049] In the case of an EVOH resin having a primary hydroxyl group in a side chain, the content of structural units derived from a monomer having the primary hydroxyl group is usually 0.1 to 20 mol %, preferably 0.5 to 15 mol %, and particularly preferably 1 to 10 mol %.

[0050] The EVOH resin (B) used in this embodiment may be a "post-modified" EVOH resin such as urethanized, acetalized, cyanoethylated, or oxyalkylenated.

[0051] When the post-modified EVOH resin is used, the modification rate is usually 10 mol % or less, and preferably 4 mol % or less. When the modification rate of the EVOH resin is equal to or less than the upper limit, thermal degradation is suppressed and the long-run property tends to be excellent.

[0052] Furthermore, the EVOH resin (B) used in the present embodiment may be a mixture of two or more types of EVOH resins, for example, EVOH resins having different ethylene structural unit contents, different degrees of saponification, different degrees of polymerization, or different copolymerization components, and preferably contains two or more types of EVOH resins having different ethylene structural unit contents.

[0053] The number of types of EVOH resins having different ethylene structural unit contents is usually 2 to 4, preferably 2 to 3, and more preferably 2. When the number of types is within the above range, productivity and economic efficiency tend to be good. In particular, it is preferable to include EVOH resin (B1) and EVOH resin (B2) having different ethylene structural unit contents.

[0054] The number of EVOH resins containing different proportions of ethylene structural units in an EVOH resin can be confirmed, for example, from the number of peaks measured using a differential scanning calorimeter (DSC) described below. The proportions of the ethylene structural units contained in the EVOH resin (B) can be determined, for example, by measuring the melting peak temperature and comparing it with the melting peak temperature of an EVOH resin whose proportions of ethylene structural units are known. From the above, the proportions of the ethylene structural units contained in two or more EVOH resins contained in the EVOH resin (B) can be calculated by measuring the melting peak temperature and the number of melting peaks of the EVOH resin. Furthermore, the melting peak temperature and the number of melting peaks of the EVOH resin (B) can be measured, and these results, together with the above-mentioned 1 By combining and analyzing the results of the ethylene structural unit content obtained by H-NMR measurement, the blending ratios of EVOH resins having different ethylene structural unit contents can be calculated. The melting peak temperature refers to the peak temperature measured by DSC when the temperature is increased from -50°C to 230°C at 10°C / min, decreased from 230°C to -50°C at 10°C / min, and then increased again from -50°C to 230°C at 10°C / min.

[0055] The difference in the content of ethylene structural units between the EVOH resin (B1) and the EVOH resin (B2) is usually 4 mol% or more, preferably 5 to 30 mol%, more preferably 6 to 25 mol%, and even more preferably 7 to 20 mol%. The content of ethylene structural units in the EVOH resin (B1) and the EVOH resin (B2) is preferably higher in the EVOH resin (B2) than in the EVOH resin (B1). Specifically, it is more preferable for the EVOH resin (B1) to contain at least 20 to 34 mol% of ethylene structural units and EVOH resin (B2) to contain 35 to 60 mol% of ethylene structural units.

[0056] The melting peak temperature difference of the EVOH resin (B) (the difference in melting point between the EVOH resin (B1) and the EVOH resin (B2)) obtained using the DSC is usually 3° C. or more, preferably 3 to 40° C., more preferably 6 to 24° C., and particularly preferably 8 to 16° C. When the temperature difference is equal to or greater than the lower limit, the balance between moldability and gas barrier property tends to be well maintained, and when the temperature difference is equal to or less than the upper limit, processability and compatibility with each other tend to be excellent.

[0057] The content of ethylene structural units in the EVOH resin (B1) is usually 20 to 34 mol%, preferably 22 to 32 mol%, and more preferably 24 to 30 mol%. When the content of ethylene structural units is equal to or greater than the lower limit, secondary processability and flexibility tend to be excellent, and when the content is equal to or less than the upper limit, gas barrier properties tend to be good.

[0058] The content of ethylene structural units in the EVOH resin (B2) is usually 35 to 60 mol%, preferably 38 to 55 mol%, and more preferably 40 to 51 mol%. When the content of such ethylene structural units is equal to or greater than the lower limit, secondary processability and flexibility tend to be excellent, while when it is equal to or less than the upper limit, gas barrier properties tend to be good. When the difference in the content of such ethylene structural units is equal to or greater than the lower limit, thickness deviation and cracks tend to be less likely to occur during molding of the multilayer structure, while when it is equal to or less than the upper limit, gas barrier properties and appearance tend to be good.

[0059] The saponification degree of the EVOH resin (B1) is usually 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%, and even more preferably 99.5 to 100 mol%. When the saponification degree is within the above range, the gas barrier property, thermal stability, moisture resistance, etc. tend to be good.

[0060] The saponification degree of the EVOH resin (B2) is usually 90 to 99.7 mol%, preferably 93 to 99.5 mol%, and more preferably 95 to 99 mol%. When the saponification degree is equal to or greater than the lower limit, the gas barrier properties, thermal stability, moisture resistance, etc. tend to be good, and when the saponification degree is equal to or less than the upper limit, the secondary processability and flexibility tend to be good.

[0061] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B1) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and more preferably 3 to 10 g / 10 min. When the MFR is equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0062] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B2) is usually 1 to 100 g / 10 min, preferably 2 to 50 g / 10 min, and more preferably 3 to 30 g / 10 min. When the MFR is equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0063] In the combination of EVOH resin (B1) and EVOH resin (B2), the molecular weights of the respective EVOH resins are preferably adjusted so that the difference (ΔMFR) in MFR (210°C, load 2160 g) is 5 g / 10 min or less, more preferably 1.5 g / 10 min or less, so that the flow properties of the resins during melt molding are similar.

[0064] The density of the EVOH resin (B) is 0.8 to 2.55 g / cm for both the EVOH resin (B1) and the EVOH resin (B2). 3When the density of the EVOH resin (B) is within the above range, stable extrusion molding tends to be possible.

[0065] The content of EVOH resin (B) in the resin composition (1) is not particularly limited, but is preferably 0.01 to 15.0 mass %, more preferably 0.05 to 13.0 mass %, even more preferably 3.0 to 12.5 mass %, particularly preferably 4.0 to 12.0 mass %, and most preferably 7.0 to 11.0 mass %, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0066] In the resin composition (1), the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) [(A) / (B)] is usually 10 / 90 to 99 / 1, preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 97 / 3, even more preferably 70 / 30 to 95 / 5, and particularly preferably 80 / 20 to 94 / 6. When the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) is within the above range, a resin composition having better thermal stability can be obtained.

[0067] In addition, in the present resin composition (1), the proportion of the total content of the EVOH resin (B) and the polypropylene resin (A) containing 14 carbon atoms in the entire resin composition is not particularly limited, but is usually 70 mass% or more, preferably 75 mass% or more, and more preferably 80 mass% or more.

[0068] In the resin composition (1), when the EVOH resin (B) contains the EVOH resins (B1) and (B2), the mass ratio (B1 / B2) of the EVOH resin (B1) to the EVOH resin (B2) is preferably 99 / 1 to 30 / 70, more preferably 95 / 5 to 30 / 70, even more preferably 90 / 10 to 40 / 60, and particularly preferably 85 / 15 to 50 / 50.

[0069] <Acid-Modified Polyolefin Resin (C)> Examples of the acid-modified polyolefin resin (C) include graft-modified polyolefin resins obtained by graft-modifying a polyolefin resin with an acid, and olefin copolymers obtained by copolymerizing an olefin with an acid. These may be used alone or in combination of two or more. Among these, modified polyolefins graft-modified with an unsaturated carboxylic acid and / or a derivative thereof are preferred, and from the viewpoint of achieving better compatibility with the carbon-14-containing polypropylene resin (A), the acid-modified polyolefin resin (C) is preferably polypropylene modified with an acid. That is, the acid-modified polyolefin resin (C) is preferably acid-modified polypropylene, and an acid-modified polypropylene resin obtained by modifying the same type of polypropylene resin as the carbon-14-containing polypropylene resin (A) is preferred.

[0070] Examples of unsaturated carboxylic acids used to modify the acid-modified polyolefin resin (C) include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, and maleic acid, and examples of derivatives thereof include acid anhydrides such as maleic anhydride and itaconic anhydride. Of these, maleic anhydride is most suitable.

[0071] Furthermore, from the viewpoint of more effectively obtaining the effects of the present invention, the acid-modified polyolefin resin (C) is preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, more preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, even more preferably an acid-modified ethylene-α-olefin copolymer obtained by acid-modifying a copolymer of ethylene and an α-olefin having 2 to 8 carbon atoms, particularly preferably an acid-modified ethylene-butene copolymer, and particularly preferably a maleic anhydride-modified ethylene-butene copolymer.

[0072] The acid-modified polyolefin resin (C) has a melt flow rate (MFR: 190°C, 2160 g load) of 0.01 to 15 g / 10 min, preferably 0.5 to 10 g / 10 min. When the MFR of the acid-modified polyolefin resin (C) is within the above range, the viscosity of the acid-modified polyolefin resin (C) and the polypropylene resin (A) containing 14 carbon atoms is well balanced. As a result, the dispersibility of the EVOH resin (B) tends to be further improved.

[0073] The density of the acid-modified polyolefin resin (C) is 0.855 to 0.955 g / cm 3 When the density of the acid-modified polyolefin resin (C) is within the above range, stable extrusion molding tends to be possible.

[0074] The amount of the unsaturated carboxylic acid and / or its derivative contained in the acid-modified polyolefin resin (C) is not particularly limited, but is preferably 0.001 to 20 mass %, more preferably 0.01 to 10 mass %, even more preferably 0.1 to 5 mass %, and particularly preferably 0.5 to 3 mass % of the acid-modified polyolefin resin (C). When the amount of the unsaturated carboxylic acid and / or its derivative in the acid-modified polyolefin resin (C) is within the above range, the dispersibility of the EVOH resin (B) in the resin composition (1) tends to be further improved.

[0075] The acid-modified polyolefin resin (C) may be used alone, or more preferably, two or more kinds of resins having different types of resins or different physical properties before modification are mixed.

[0076] The content of the acid-modified polyolefin resin (C) in the resin composition (1) is usually 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 13% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 4% by mass or more and 9% by mass or less, based on the total mass of the resin composition. When this value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0077] <Other Components> The resin composition (1) may contain resins other than the polypropylene resin (A) containing 14 carbon atoms, the EVOH resin (B), and the acid-modified polyolefin resin (C) (e.g., petroleum-derived polypropylene resin, other types of resins), and optional additives (hereinafter, these are referred to as "other components") according to various purposes, within the scope of not significantly impairing the effects of the present invention. Only one type of other component may be used, or two or more types may be used in any combination and ratio.

[0078] Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents.

[0079] When the present resin composition (1) contains the "other components," the total content of these components is usually 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the present resin composition (1). The lower limit is usually 0% by mass. Such a content is usually 0 to 30% by mass, etc.

[0080] <Method for Producing Resin Composition (1)> The resin composition (1) can be produced by mixing the essential components, carbon-14-containing polypropylene resin (A), EVOH resin (B), and acid-modified polyolefin resin (C), as well as the other components as needed. Examples of the mixing method include known methods such as dry blending, melt mixing using a single-screw extruder or twin-screw extruder to obtain a compound, solution mixing, and impregnation, and these can be combined in any desired manner. The carbon-14-containing polypropylene resin (A), EVOH resin (B), and acid-modified polyolefin resin (C) can be recycled resins obtained by pulverizing scraps of multilayer structures containing carbon-14-containing polypropylene resin layers, EVOH resin layers, and acid-modified polyolefin resin layers.

[0081] The resin composition (1) thus obtained is less likely to decompose under high temperature heating and has excellent thermal stability compared to conventional resin compositions obtained by combining an EVOH resin and a petroleum-derived polypropylene resin.

[0082] The biobased content of the resin composition (1) is usually 0.01 to 99%, preferably 0.1 to 90%, more preferably 1 to 80%, even more preferably 1 to 70%, and particularly preferably 10 to 60%. By setting the biobased content of the resin composition within this range, a resin composition with better thermal stability can be obtained.

[0083] The content of carbon-14 in the resin composition (1) is not particularly limited, but the ratio of carbon-14 to the total carbon in the resin composition is usually 1.0 × 10 -16 or more, 1.0 × 10 -14 The upper limit is usually 1.2 × 10 -12 is.

[0084] The melt flow rate (MFR) (210°C, load 2160 g) of the resin composition (1) is usually 0.1 to 100 g / 10 min, preferably 0.5 to 90 g / 10 min, more preferably 2 to 80 g / 10 min.

[0085] The water content of the resin composition (1) is usually 0.01 to 0.5% by mass, preferably 0.02 to 0.35% by mass, and more preferably 0.05 to 0.3% by mass.

[0086] The water content of the resin composition (1) is measured and calculated by the following method: The mass (W1) of the resin composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula: Water content (mass%) = [(W1 - W2) / W1] x 100

[0087] The present resin composition (1) is prepared as a resin composition in various forms, such as pellets or powder, and is provided as a material for various molded articles and multilayer structures. As described above, the present resin composition (1) has excellent thermal stability, so molded articles using the present resin composition (1) or multilayer structures having a layer using the present resin composition (1) are of excellent quality. In particular, in this embodiment, when the present resin composition (1) is provided as a material for melt molding, the effects of the present invention tend to be more efficiently obtained, which is preferable.

[0088] [Molded Article] A molded article according to one embodiment of the present invention (hereinafter referred to as the "present molded article") is obtained by molding the present resin composition (1).

[0089] Examples of the shape of the present molded article include films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc. That is, the present resin composition (1) can be suitably used as any of films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc.

[0090] The molding method of the resin composition (1) is not particularly limited, and any molding method applicable to general resin compositions can be used, such as extrusion molding, blow molding, injection molding, thermoforming, etc.

[0091] [Multilayer structure] A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure") has at least one layer containing the present resin composition (1). The present multilayer structure can be further strengthened or imparted with other functions by being laminated with another substrate (hereinafter referred to as "substrate resin") containing a thermoplastic resin other than the present resin composition (1) as a main component.

[0092] Examples of the base resin include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and the side chain); and polyolefins containing unsaturated carboxylic acid. Examples of the polyolefin resin include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with an acid or an ester thereof, 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, and aromatic or aliphatic polyketones.

[0093] Of these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred from the viewpoint of economy and productivity, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof.

[0094] The layer structure of the present multilayer structure 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, or b2 / b1 / a / b1 / a / b1 / b2, where a represents the resin composition layer and b represents the base resin layer. It is also possible to provide a recycled layer containing a mixture of the present resin composition (1) and the base resin, obtained by remelting and molding end portions or defective products generated during the manufacturing process of the multilayer structure. The total number of layers in the multilayer structure is usually 2 to 15, preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between each layer, if necessary.

[0095] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples of the carboxyl-containing modified polyolefin polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. One or a mixture of two or more selected from these can be used.

[0096] In the present multilayer structure, when an adhesive resin layer is used between the resin composition layer and the substrate resin layer, since the adhesive resin layers are located on both sides of the resin composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0097] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin).

[0098] The resin composition (1) can be laminated with the substrate resin (including through an adhesive resin layer) by a known method. Examples of such methods include melt-extrusion laminating the substrate resin onto a film, sheet, or the like of the resin composition (1), melt-extrusion laminating the resin composition (1) onto a substrate resin layer, co-extruding the resin composition with the substrate resin, dry-laminating the resin composition layer and the substrate resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and applying a solution of the resin composition onto the substrate resin and then removing the solvent. Among these, from the viewpoints of cost and the environment, the method of co-extruding the resin composition with the substrate resin is preferred.

[0099] The multilayer structure is optionally subjected to a (heat) stretching treatment. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0100] For the purpose of imparting dimensional stability, heat setting may be carried out after the stretching treatment. Heat setting can be carried out by known means, for example, by heat treating the stretched film while maintaining it in a tensile state, usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds. When the multilayer stretched film obtained from the present resin composition (1) is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0101] In some cases, the multilayer structure can be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0102] The thickness of the multilayer structure (including a stretched structure), and the thicknesses of the resin composition layer, substrate resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generally determined depending on the layer configuration, type of substrate resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the multilayer structure (including a stretched structure) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, and more preferably 50 to 2,000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, and more preferably 5 to 200 μm. The substrate resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and more preferably 20 to 1,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and more preferably 3 to 100 μm.

[0103] Furthermore, the thickness ratio of the resin composition layer to the substrate resin layer (resin composition layer / substrate resin layer), when there are multiple layers of each type, is typically 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Furthermore, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer), when there are multiple layers of each type, is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0104] In the present multilayer structure, the layer containing the present resin composition (1) is preferably a layer (regrind layer) formed using the present resin composition (1) (= recycled resin composition) containing a polypropylene resin layer containing carbon-14, an EVOH resin layer, and an acid-modified polyolefin resin layer. Such a multilayer structure having a regrind layer will be described below.

[0105] The recycled materials of the multilayer structure containing a carbon-14-containing polypropylene resin layer, an EVOH resin layer, and an acid-modified polyolefin resin layer used to obtain the regrind layer are scraps, unnecessary parts such as end parts, defective products, and waste materials collected during the production of the multilayer structure, or waste materials collected after the molded body has been used for various purposes. These recycled materials can be reused to prepare the present resin composition (1), which can be used to obtain the regrind layer.

[0106] To obtain the regrind layer, for example, the recycled material (a composition containing a carbon-14-containing polypropylene resin (A), an EVOH resin (B), and an acid-modified polyolefin resin (C)) is appropriately combined with other optional components, and, if necessary, additional carbon-14-containing polypropylene resin (A), an EVOH resin (B), and an acid-modified polyolefin resin (C) are added. By uniformly mixing these components, the present resin composition (1), which is a recycled resin composition, is obtained. The present resin composition (1) is then melt-molded and co-extruded to obtain the present multilayer structure having a regrind layer.

[0107] In order to re-submit the recovered multilayer structure containing the carbon-14-containing polypropylene resin layer, the EVOH resin layer, and the acid-modified polyolefin resin layer to melt molding in an extruder or the like, it is preferable to pulverize the recovered material. The pulverization can be carried out using a known pulverizer. The shape and particle size of the pulverized material, as measured in accordance with the "5.3 Apparent Density" test method of JIS-K6891, are typically 0.25 to 0.85 g / mL, preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. Having an apparent density equal to or greater than the lower limit of this range improves dispersion of the EVOH resin in the regrind layer, and the resulting molded article tends to have excellent melt moldability and mechanical properties. Having an apparent density equal to or less than the upper limit of this range stabilizes feeding in the extruder, and the melt moldability of the regrind layer of the molded article tends to be improved.

[0108] The apparent density can be controlled by adjusting the shape of the crushing blade of the crusher, the number of revolutions of the crushing blade, the crushing processing speed, the size of the openings of the mesh used, and the like.

[0109] The multilayer structure having a regrind layer is generally preferably a multilayer structure that further includes, in addition to the regrind layer, a layer containing a polyolefin resin, an adhesive layer, and an EVOH resin layer, where the EVOH resin layer means a layer containing an EVOH resin different from the regrind layer.

[0110] The thickness of each layer of the regrind layer-containing multilayer structure cannot be generalized depending on the layer configuration, type of polyolefin resin, intended use, container shape, required physical properties, etc., but the regrind layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. The EVOH resin layer is usually 5 to 500 μm, preferably 10 to 200 μm. The polyolefin resin layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. In this case, if an adhesive resin layer is present, the adhesive resin layer is usually 5 to 400 μm, preferably 10 to 150 μm.

[0111] The thickness ratio of the regrind layer to the polyolefin resin layer is usually 1 / 5 to 10 / 1, preferably 1 / 2 to 5 / 1, and the thickness ratio of the regrind layer to the EVOH resin layer is usually 1 / 1 to 100 / 1, preferably 5 / 1 to 20 / 1.

[0112] The regrind layer-containing multilayer structure can be used to obtain, for example, cup- or tray-shaped multilayer containers by the same method as used to mold the multilayer structure.

[0113] The films, sheets, and bags made of the stretched films obtained as described above, and containers such as cups, trays, tubes, and bottles are useful as various packaging materials and containers for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, and the like.

[0114] <<Second Aspect>> The second aspect includes the following items <II-1> to <II-19>. <II-1> A resin composition comprising a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C), wherein the ethylene-vinyl alcohol copolymer (B) contains a structural unit having a primary hydroxyl group in a side chain. <II-2> The resin composition according to <II-1>, wherein the carbon-14 containing polypropylene resin (A) includes a bio-polypropylene resin. <II-3> The resin composition according to <II-1> or <II-2>, excluding the following resin composition [α] from the resin composition: A resin composition [α] comprising a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) contains a structural unit having a primary hydroxyl group in its side chain, and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the group consisting of elements belonging to the d block of Period 4 of the Long Form Periodic Table. <II-4> The resin composition according to any one of <II-1> to <II-3>, wherein the carbon-14 containing polypropylene resin (A) is a homopolypropylene. <II-5> The resin composition according to any one of <II-1> to <II-4>, wherein the carbon-14 containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having from 10 to 24 carbon atoms. <II-6> The resin composition according to any one of <II-1> to <II-5>, wherein the ethylene structural unit content in the ethylene-vinyl alcohol copolymer (B) is 20 to 60 mol %. <II-7> The resin composition according to any one of <II-1> to <II-6>, wherein the ethylene-vinyl alcohol copolymer (B) is 0.01 to 15.0 mass % relative to the entire resin composition. <II-8> The resin composition according to any one of <II-1> to <II-7>, wherein the carbon-14 containing polypropylene resin (A) is 10 mass % or more and 99 mass % or less relative to the entire resin composition.<II-9> The resin composition according to any one of <II-1> to <II-8>, wherein the content of the acid-modified polyolefin resin (C) is 0.1% by mass or more and 20% by mass or less, based on the total mass of the resin composition. <II-10> A sheet comprising the resin composition according to any one of <II-1> to <II-9>. <II-11> A film comprising the resin composition according to any one of <II-1> to <II-9>. <II-12> A regrind layer comprising the resin composition according to any one of <II-1> to <II-9>. <II-13> A multilayer structure comprising the regrind layer according to <II-12>. <II-14> The multilayer structure according to <II-13>, further comprising a layer comprising a polyolefin resin. <II-15> The multilayer structure according to <II-13>, further comprising an adhesive resin layer. <II-16> The multilayer structure according to <II-13>, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer. <II-17> A molded article obtained by molding the multilayer structure according to <II-13>. <II-18> A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of <II-1> to <II-9>. <II-19> A method for producing a molded article, comprising a step of molding the multilayer structure according to <II-13>.

[0115] The present invention will be described below based on examples of modes for carrying out the second aspect, although the present invention is not limited to the embodiments described below.

[0116] <Resin composition (2)> A resin composition according to one example of an embodiment of the present invention (hereinafter referred to as "the present resin composition (2)") contains a polypropylene resin (A) containing 14 carbon atoms, an EVOH resin (B), and an acid-modified polyolefin resin (C), and the EVOH resin (B) contains a structural unit having a primary hydroxyl group in a side chain (hereinafter may be referred to as a "modified EVOH resin").

[0117] From the viewpoint of thermal stability, it is preferable that the resin composition (2) does not contain the following resin composition [α]. Resin composition [α] contains a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) contains a structural unit having a primary hydroxyl group in its side chain, and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the group consisting of elements belonging to the d block of Period 4 of the Long Periodic Table. Each component will be described below.

[0118] <Polypropylene resin (A) containing carbon-14> The polypropylene resin (A) containing carbon-14 used in the present resin composition (2) can be the same as the <Polypropylene resin (A) containing carbon-14> described in the first embodiment.

[0119] The resin composition (2) contains the polypropylene resin (A) containing 14 carbon atoms in a resin composition containing the modified EVOH resin (B), and therefore has superior thermal stability compared to resin compositions containing conventional petroleum-derived polypropylene resins.

[0120] The mechanism is thought to be as follows. It is known that petroleum-derived polypropylene resins are easily oxidized by heat, generating hydroperoxides and causing degradation reactions such as molecular weight reduction. One known method for suppressing such thermal degradation is to improve the thermal stability of polypropylene by adding a hindered phenol or other antioxidant. However, because such antioxidants tend to interact with modified EVOH resins, the thermal stability improvement effect is not fully achieved. In particular, when added in large amounts, the antioxidant's anti-discoloration effect and mechanical properties tend to deteriorate. In such resin compositions containing polypropylene resin and modified EVOH resin as essential components, the use of a carbon-14-containing polypropylene resin (A) strengthens the bond energy due to the primary isotope effect. As a result, it is presumed that the decomposition of the carbon-14-containing polypropylene resin (A) itself is slowed, resulting in enhanced thermal stability. Furthermore, since thermal stability can be improved without affecting the modified EVOH resin (B), it is presumed that an excellent thermal stability improvement effect can be achieved.

[0121] The carbon-14-containing polypropylene resin (A) used in the resin composition (2) typically has a biobased content of 1 to 99%, preferably 5 to 95%, more preferably 10 to 90%, even more preferably 20 to 80%, and particularly preferably 30 to 70%. By adjusting the biobased content of the carbon-14-containing polypropylene resin (A) to fall within the above range, a resin composition with even better thermal stability can be obtained.

[0122] The content of the carbon-14 containing polypropylene resin (A) is typically 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total content of the resin composition (2). The upper limit is typically 99% by mass, preferably 96% by mass. The range of such a content is typically 10% by mass or more and 99% by mass or less. By setting the content of the carbon-14 containing polypropylene resin (A) within the above range, a resin composition with better thermal stability can be obtained.

[0123] <EVOH Resin (B)> EVOH resin is a thermoplastic resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is mainly composed of ethylene structural units and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain unsaponified.

[0124] The EVOH resin (B) contained in the resin composition (2) is a modified EVOH resin having a primary hydroxyl group in a side chain, specifically an EVOH resin having a structural unit of the following general formula (1). The modified EVOH resin (B) is particularly preferred from the viewpoint of excellent moldability and mechanical properties.

[0125]

[0126] R 1 ~R 3 is not particularly limited as long as it is a hydrogen atom or an organic group. Examples of the organic group include hydrocarbon groups such as alkyl groups, alkenyl groups, alkynyl groups, phenyl groups, and naphthyl groups (these hydrocarbon groups may have a hydroxyl group, fluorine, chlorine, bromine, or the like as a substituent).

[0127] The linking chain (X) linking the polymer main chain and the primary hydroxyl group structure is not particularly limited, and examples thereof include hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbons may have a hydroxyl group, fluorine, chlorine, bromine, or the like as a substituent), hydrocarbons bonded to the polymer main chain by an ether bond such as oxyalkylene, oxyalkenylene, oxyalkynylene, oxyphenylene, and oxynaphthylene (these hydrocarbons may have a hydroxyl group, fluorine, chlorine, bromine, or the like as a substituent), as well as -CO-, -CO(CH2)mCO-, -CO(CH2)mCOR 4 -, -NR 5 --, --CONR 5 - and the like (R 4 , R 5 are independently any substituent, preferably a hydrogen atom or an alkyl group, and m is a natural number.

[0128] The modified EVOH resin (B) can be obtained, for example, by the following methods: (I) copolymerizing a monomer having a primary hydroxyl group structural unit in the side chain or a monomer in which the primary hydroxyl group structural unit in the side chain is protected with an ester or the like with ethylene and a vinyl ester monomer, followed by deprotection by saponification or the like; or (II) first saponifying a copolymer of ethylene and a vinyl ester monomer to obtain an EVOH resin, and then post-modifying the EVOH resin to generate a primary hydroxyl group structural unit in the side chain. Among these, method (I) is preferred from the viewpoint of productivity. The method for producing modified EVOH resin (B) will be described below.

[0129] First, in the case of the method (I), ethylene, a vinyl ester monomer, and a monomer having a primary hydroxyl group structural unit in the side chain or a monomer in which the hydroxyl group structural unit is protected with an ester or the like may be copolymerized.

[0130] Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate, vinyl trifluoroacetate, etc. Among these, vinyl acetate is preferred from an economical viewpoint.

[0131] In the method (I), examples of the monomer having a primary hydroxyl group structural unit in the side chain include monohydroxyalkyl group-containing monomers such as allyl alcohol, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 6-hepten-1-ol, and methallyl alcohol; and dihydroxyalkyl group-containing monomers such as 2-methylene-1,3-propanediol, 3,4-diol-1-butene, 4,5-diol-1-pentene, 4,5-diol-3-methyl-1-pentene, 5,6-diol-1-hexene, and glycerin monoallyl ether. These can be used alone or in combination of two or more.

[0132] Furthermore, in the method (I) above, examples of the monomer in which the primary hydroxyl group structural unit in the side chain is protected with an ester or the like (hereinafter, sometimes referred to as "monomer in which the hydroxyl group structural unit is protected with an ester or the like") include acetate esters of the monomers having a primary hydroxyl group structural unit in the side chain. Specific examples include monoacetoxyalkyl group-containing monomers such as allyl acetate, 3-butenyl acetate, 4-pentenyl acetate, 5-hexenyl acetate, 6-heptenyl acetate, and methallyl acetate; and diacetoxyalkyl group-containing monomers such as 2-methylene-1,3-propanediol diacetate, 3,4-diacetoxy-1-butene, 4,5-diacetoxy-1-pentene, 4,5-diacetoxy-3-methyl-1-pentene, 5,6-diacetoxy-1-hexene, and 3-allyloxy-1,2-propanediol diacetate. These can be used alone or in combination of two or more.

[0133] In the above method (I), a monomer having a primary hydroxyl group structural unit in the side chain and a monomer in which the hydroxyl group structural unit is protected with an ester or the like can be used in combination and copolymerized with ethylene and a vinyl ester monomer.

[0134] Among these, from the viewpoint of productivity, monomers in which the hydroxyl group structural unit is protected with an ester or the like are preferred, diacetoxyalkyl group-containing monomers are more preferred, 3,4-diacetoxy-1-butene and 2-methylene-1,3-propanediol diacetate are more preferred, and 3,4-diacetoxy-1-butene is particularly preferred.

[0135] Furthermore, copolymerizable ethylenically unsaturated monomers may be copolymerized within a range that does not impair the effects of the present invention. Examples of such ethylenically unsaturated monomers include olefins such as propylene, 1-butene, and isobutene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid, or salts thereof, or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylmethacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid, or salts thereof; acrylamides such as acrylamidopropyldimethylamine, acid salts thereof, or quaternary salts thereof; methacrylamide, alkyl groups such as methacrylamide, Examples of suitable vinyl silanes include methacrylamides having 1 to 18 carbon atoms, such as N-alkylmethacrylamides, N,N-dimethylmethacrylamide, and 2-methacrylamidopropanesulfonic acid or salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl ethers such as alkyl vinyl ethers, hydroxyalkyl vinyl ethers, and alkoxyalkyl vinyl ethers, each of which has an alkyl group having 1 to 18 carbon atoms; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; and vinylsilanes. These may be used alone or in combination of two or more.

[0136] In these copolymerization reactions, known methods can be used, such as bulk polymerization, solution polymerization, suspension polymerization, dispersion polymerization, emulsion polymerization, etc. Among these, solution polymerization is preferably used because it is easy to control the copolymerization.

[0137] When such copolymerization is carried out by solution polymerization, examples of the solvent used include lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, propanol, 2-propanol, and butanol, and ketones, such as acetone and 2-butanone. These can be used alone or in combination of two or more. Of these, methanol is preferred because of the ease of controlling the polymerization reaction. Furthermore, 2-propanol is preferred when synthesizing a copolymer with a low degree of polymerization.

[0138] The amount of the solvent used can be appropriately selected taking into consideration the degree of polymerization of the desired modified EVOH resin (B) and the chain transfer constant of the solvent. When the solvent is methanol or 2-propanol, the weight ratio of S (solvent) / M (monomer) is preferably 0.01 to 10, and more preferably 0.05 to 7.

[0139] As a method for charging the copolymerization components in solution polymerization, any method can be adopted, such as initial lump-sum charging, divided charging, or continuous charging such as the Hanna method taking into consideration the reactivity ratio of the monomers.

[0140] A polymerization initiator is used for the copolymerization. Examples of such polymerization initiators include azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and peroxide initiators such as acetyl peroxide, benzoyl peroxide, lauryl peroxide, t-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, diisopropyl peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate.

[0141] The amount of the polymerization catalyst used cannot be generally determined because it varies depending on the type of polymerization catalyst, but is selected as appropriate depending on the polymerization rate. For example, when 2,2'-azobisisobutyronitrile or t-butylperoxyneodecanoate is used, the amount is usually 10 to 2000 ppm, and preferably 50 to 1000 ppm, based on the vinyl ester monomer.

[0142] The polymerization temperature for copolymerization is preferably selected from the range of 40° C. to the boiling point depending on the solvent used and the ethylene pressure.

[0143] Furthermore, copolymerization may be carried out in the presence of a chain transfer agent, provided that the effects of the present invention are not impaired. Examples of chain transfer agents include aldehydes such as acetaldehyde, propionaldehyde, and crotonaldehyde; and mercaptans such as 2-hydroxyethanethiol. These may be used alone or in combination of two or more. Among these, aldehydes are preferred. The amount of chain transfer agent added during copolymerization is determined depending on the chain transfer constant of the chain transfer agent and the desired degree of polymerization of the modified EVOH resin (B), but is generally preferably 0.1 to 10 parts by mass per 100 parts by mass of vinyl ester monomer.

[0144] The ethylene-vinyl ester copolymer thus obtained can be saponified to obtain the modified EVOH resin (B).

[0145] The saponification can be carried out by a known method, for example, by dissolving the ethylene-vinyl ester copolymer obtained above in alcohol or aqueous alcohol and using a saponification catalyst.

[0146] Examples of the alcohol include lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, and propanol. These may be used alone or in combination of two or more. Of these, methanol is preferred.

[0147] 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.

[0148] Examples of the saponification catalyst include alkali catalysts such as hydroxides and alcoholates of alkali metals, 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.

[0149] The temperature at which the saponification is carried out is not limited, but a range of 20 to 140°C is suitable. As the saponification proceeds, particulate matter is produced, indicating that the reaction has progressed. If a gel-like product precipitates at this time, the product can be pulverized. The produced granules can be washed and dried to obtain the modified EVOH resin (B). In order to increase the degree of saponification, the produced granules can be washed and then dispersed again in alcohol or the like, and an alkali catalyst can be added to further react.

[0150] The saponification converts the vinyl ester units in the ethylene-vinyl ester copolymer to vinyl alcohol units. When a monomer in which a hydroxyl group structural unit is protected with an ester or the like is copolymerized, the ester or the like of the protected monomer is simultaneously deprotected by the saponification and converted to a side chain primary hydroxyl group structure.

[0151] When 3,4-diacetoxy-1-butene is used as a copolymerization component in the above method (I), the modified EVOH resin obtained by deprotection by saponification or the like has a primary hydroxyl group represented by the following general formula (2) in its side chain.

[0152]

[0153] When 2-methylene-1,3-propanediol diacetate is used as a copolymerization component in the above method (I), the resulting modified EVOH resin has a primary hydroxyl group represented by the following general formula (3) in the side chain.

[0154]

[0155] When the modified EVOH resin (B) is produced by the method (II) above, for example, ethylene and a vinyl ester monomer exemplified in the method (I) above, and optionally a copolymerizable ethylenically unsaturated monomer exemplified in the method (I) above, are copolymerized in accordance with the method (I) above to produce an EVOH resin, and the resulting EVOH resin is then reacted with a monovalent epoxy group-containing compound. The reaction method is not particularly limited, but suitable methods include a solution reaction method and an extruder reaction method. When the extruder reaction method is employed, it is also preferable to use a catalyst containing ions of a metal belonging to Groups 3 to 12 of the periodic table.

[0156] Examples of the monovalent epoxy group-containing compound include propylene oxide, butylene oxide, and glycidol. These can be used alone or in combination of two or more. Among these, propylene oxide is preferred.

[0157] When propylene oxide is used as the monovalent epoxy group-containing compound, the resulting modified EVOH resin has a primary hydroxyl group structural unit represented by the following general formula (4) in the side chain.

[0158]

[0159] By using the method (I) or (II), a modified EVOH resin (B) having the structural unit of the above general formula (1) can be obtained. The modified EVOH resin may have a primary hydroxyl group structural unit in the side chain, and may also have other hydroxyl group structures (secondary hydroxyl groups or tertiary hydroxyl groups) in the side chain. The modified EVOH resin may not be completely deprotected, and a small amount of ester may remain.

[0160] The content of ethylene structural units in the modified EVOH resin (B) is usually 20 to 60 mol%, preferably 23 to 55 mol%, and particularly preferably 25 to 50 mol%. When the content of ethylene structural units is equal to or less than the upper limit, the resin tends to have excellent gas barrier properties, and when the content is equal to or more than the lower limit, the resin tends to have good gas barrier properties and melt moldability under high humidity conditions.1 It is measured by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0161] The content of primary hydroxyl structural units in side chains in the modified EVOH resin (B) is preferably 0.1 to 30 mol%, more preferably 0.3 to 20 mol%, even more preferably 0.5 to 10 mol%, and particularly preferably 1 to 5 mol%. When the content of primary hydroxyl structural units is equal to or greater than the lower limit, the hydrophilicity of the modified EVOH resin (B) tends to be improved and the biodegradability tends to be high. Furthermore, when the content of primary hydroxyl structural units is equal to or less than the lower limit, production costs tend to be reduced, resulting in economical advantages.

[0162] The degree of saponification of the vinyl ester component in the modified EVOH resin (B) can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) used when saponifying the ethylene-vinyl ester copolymer, and is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. When the saponification degree is equal to or higher than the lower limit, the gas barrier property, thermal stability, moist heat resistance, etc. tend to be good. The degree of saponification of the modified EVOH resin (B) is usually 1 It is measured by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0163] The melt flow rate (MFR) (210°C, 2160 g load) of the modified EVOH resin (B) 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 equal to or less than the upper limit, excellent film-forming properties tend to be obtained. When the MFR is equal to or greater than the lower limit, the viscosity does not become too high and melt extrudability tends to be good. The MFR is an indicator of the degree of polymerization of the modified EVOH resin (B) and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene and a vinyl ester monomer. In this specification, the MFR can be determined by measuring the flow rate of a sample through an orifice with a length of 8 mm and a hole diameter of 2.095 mm under conditions of a temperature of 210°C and a load of 2160 g using an automatic melt flow rate tester (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0164] The modified EVOH resin (B) used in the present embodiment may also be a mixture of two or more types of modified EVOH resins, such as those having different contents of ethylene structural units, different contents of primary hydroxyl structural units, different degrees of saponification, different degrees of polymerization, or different copolymerization components.

[0165] The content of the modified EVOH resin (B) in the resin composition (2) is preferably 0.01 to 15.0 mass%, more preferably 0.05 to 13.0 mass%, even more preferably 0.1 to 9.9 mass%, particularly preferably 1.0 to 7.0 mass%, and most preferably 2.0 to 5.0 mass%, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0166] In the resin composition (2), the mass ratio [(A) / (B)] of the modified EVOH resin (B) to the polypropylene resin (A) containing 14 carbon atoms is usually 10 / 90 to 99 / 1, preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 97 / 3, still more preferably 70 / 30 to 95 / 5, and particularly preferably 80 / 20 to 94 / 6. When the mass ratio of the modified EVOH resin (B) to the polypropylene resin (A) containing 14 carbon atoms is within the above range, a resin composition having better thermal stability can be obtained.

[0167] In addition, in the present resin composition (2), the proportion of the total content of the modified EVOH resin (B) and the polypropylene resin (A) containing 14 carbon atoms in the entire resin composition is not particularly limited, but is usually 70 mass% or more, preferably 80 mass% or more, and more preferably 90 mass% or more.

[0168] <Acid-Modified Polyolefin Resin (C)> As the acid-modified polyolefin resin (C), the same as the <Acid-Modified Polyolefin Resin (C)> explained in the first embodiment can be used.

[0169] The content of the acid-modified polyolefin resin (C) in the resin composition (2) is usually 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 13% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 4% by mass or more and 9% by mass or less, based on the total mass of the resin composition. When this value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0170] <Other Components> The resin composition (2) may contain resins other than the polypropylene resin (A) containing 14 carbon atoms, the modified EVOH resin (B), and the acid-modified polyolefin resin (C) (e.g., petroleum-derived polypropylene resin, other types of resins), and optional additives (hereinafter, these are referred to as "other components") according to various purposes, within the scope of not significantly impairing the effects of the present invention. Only one type of other component may be used, or two or more types may be used in any combination and ratio.

[0171] Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents.

[0172] When the present resin composition (2) contains the "other components," the total content of these components relative to the present resin composition (2) is usually 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. The lower limit is usually 0% by mass. The content is usually 0 to 30% by mass, etc.

[0173] <Method for Producing Resin Composition (2)> The resin composition (2) can be produced by mixing the essential components, carbon-14-containing polypropylene resin (A), modified EVOH resin (B), and acid-modified polyolefin resin (C), as well as the other components as needed. Examples of the mixing method include known methods such as dry blending, melt mixing using a single-screw extruder or twin-screw extruder to obtain a compound, solution mixing, and impregnation, and these can be combined in any desired manner. The carbon-14-containing polypropylene resin (A), modified EVOH resin (B), and acid-modified polyolefin resin (C) can be recycled resins obtained by pulverizing scraps of multilayer structures containing carbon-14-containing polypropylene resin layers, modified EVOH resin layers, and acid-modified polyolefin resin layers.

[0174] The present resin composition (2) thus obtained is less likely to decompose under high temperature heating and has excellent thermal stability compared to conventional resin compositions obtained by combining modified EVOH resin and petroleum-derived polypropylene resin.

[0175] The biobased content of the resin composition (2) is usually 0.01 to 99%, preferably 0.1 to 90%, more preferably 1 to 80%, even more preferably 1 to 70%, and particularly preferably 10 to 60%. By setting the biobased content of the resin composition within this range, a resin composition with better thermal stability can be obtained.

[0176] The content of carbon-14 in the resin composition (2) is not particularly limited, but the ratio of carbon-14 to the total carbon in the resin composition is usually 1.0 × 10 -16 or more, 1.0 × 10 -14 The upper limit is usually 1.2 × 10 -12 is.

[0177] The melt flow rate (MFR) (210°C, load 2160 g) of the resin composition (2) is usually 0.1 to 100 g / 10 min, preferably 0.5 to 90 g / 10 min, more preferably 2 to 80 g / 10 min.

[0178] The water content of the resin composition (2) is usually 0.01 to 0.5% by mass, preferably 0.02 to 0.35% by mass, and more preferably 0.05 to 0.3% by mass.

[0179] The water content of the resin composition (2) is measured and calculated by the following method: The mass (W1) of the resin composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula: Water content (mass%) = [(W1 - W2) / W1] x 100

[0180] The present resin composition (2) is prepared as a resin composition in various forms, such as pellets or powder, and is provided as a material for various molded articles and multilayer structures. As described above, the present resin composition (2) has excellent thermal stability, so molded articles using the present resin composition (2) or multilayer structures having a layer using the present resin composition (2) are of excellent quality. In particular, in this embodiment, when the present resin composition (2) is provided as a material for melt molding, the effects of the present invention tend to be more efficiently obtained, which is preferable.

[0181] [Molded Article] A molded article according to one embodiment of the present invention (hereinafter referred to as the "present molded article") is obtained by molding the present resin composition (2).

[0182] Examples of the shape of the present molded article include films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc. That is, the present resin composition (2) can be suitably used as any of films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc.

[0183] The molding method of the resin composition (2) is not particularly limited, and any molding method applicable to general resin compositions can be used, such as extrusion molding, blow molding, injection molding, and thermoforming.

[0184] [Multilayer structure] A multilayer structure according to an embodiment of the present invention (hereinafter referred to as "the multilayer structure") has at least one layer containing the present resin composition (2). The present multilayer structure can be further strengthened or imparted with other functions by being laminated with another substrate (hereinafter referred to as "substrate resin") whose main component is a thermoplastic resin other than the present resin composition (2).

[0185] Examples of the base resin include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and the side chain); and polyolefins containing unsaturated carboxylic acid. Examples of the polyolefin resin include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with an acid or an ester thereof, 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, and aromatic or aliphatic polyketones.

[0186] Of these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred from the viewpoint of economy and productivity, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof.

[0187] The layer structure of the present multilayer structure 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, or b2 / b1 / a / b1 / a / b1 / b2, where a represents the resin composition layer and b represents the base resin layer (b1, b2, etc.). It is also possible to provide a recycled layer containing a mixture of the present resin composition (2) and the base resin, obtained by remelting and molding end portions or defective products generated during the manufacturing process of the multilayer structure. The total number of layers in the multilayer structure is usually 2 to 15, preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between each layer, if necessary.

[0188] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples of the carboxyl-containing modified polyolefin polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. One or a mixture of two or more selected from these can be used.

[0189] In the present multilayer structure, when an adhesive resin layer is used between the resin composition layer and the base resin layer, since the adhesive resin layers are located on both sides of the resin composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0190] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin).

[0191] The resin composition (2) can be laminated with the base resin (including through an adhesive resin layer) by a known method. Examples of such methods include melt-extrusion laminating the base resin onto a film, sheet, or the like of the resin composition (2), melt-extrusion laminating the resin composition (2) onto a base resin layer, co-extruding the resin composition with the base resin, dry-laminating the resin composition layer and the base resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and applying a solution of the resin composition onto the base resin and then removing the solvent. Among these, from the standpoints of cost and the environment, the method of co-extruding the resin composition with the base resin is preferred.

[0192] The multilayer structure is optionally subjected to a (heat) stretching treatment. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0193] For the purpose of imparting dimensional stability, heat setting may be carried out after the stretching treatment. Heat setting can be carried out by known means, for example, by heat treating the stretched film while maintaining it in a tensile state, usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds. When the multilayer stretched film obtained from the present resin composition (2) is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0194] In some cases, the multilayer structure can be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0195] The thickness of the multilayer structure (including a stretched structure), as well as the thickness of the resin composition layer, substrate resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generally determined depending on the layer configuration, type of substrate resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the multilayer structure (including a stretched structure) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, more preferably 50 to 2,000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, more preferably 5 to 200 μm. The substrate resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, more preferably 20 to 1,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, more preferably 3 to 100 μm.

[0196] Furthermore, the thickness ratio of the resin composition layer to the base resin layer in the multilayer structure (resin composition layer / base resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Furthermore, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0197] In the present multilayer structure, the layer containing the present resin composition (2) is preferably a layer (regrind layer) formed using the present resin composition (2) (= recycled resin composition) containing a polypropylene resin layer containing carbon-14, a modified EVOH resin layer, and an acid-modified polyolefin resin layer. Such a multilayer structure having a regrind layer will be described below.

[0198] The recycled materials of the multilayer structure containing a carbon-14-containing polypropylene resin layer, a modified EVOH resin layer, and an acid-modified polyolefin resin layer used to obtain the regrind layer are scraps, unnecessary parts such as end parts, defective products, and waste after the molded body has been used for various purposes, collected during the production process. These recycled materials can be reused to prepare the present resin composition (2), which can be used to obtain the regrind layer.

[0199] To obtain the regrind layer, for example, the recycled material (a composition containing a carbon-14-containing polypropylene resin (A), a modified EVOH resin (B), and an acid-modified polyolefin resin (C)) is appropriately combined with other optional components, and, if necessary, additional carbon-14-containing polypropylene resin (A), a modified EVOH resin (B), and an acid-modified polyolefin resin (C) are added. By uniformly mixing these components, the present resin composition (2), which is a recycled resin composition, is obtained. The present multilayer structure having a regrind layer can then be obtained by melt-molding and co-extruding the present resin composition (2).

[0200] In order to re-submit the recovered multilayer structure containing the carbon-14-containing polypropylene resin layer, the modified EVOH resin layer, and the acid-modified polyolefin resin layer to melt molding using an extruder or the like, it is preferable to pulverize the recovered material. The pulverization can be carried out using a known pulverizer. The shape and particle size of the pulverized material, as measured in accordance with the "5.3 Apparent Density" test method of JIS-K6891, are typically 0.25 to 0.85 g / mL, preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. Having an apparent density equal to or greater than the lower limit of this range improves dispersion of the modified EVOH resin (B) in the regrind layer, and the resulting molded article tends to have excellent melt moldability and mechanical properties. Having an apparent density equal to or less than the upper limit of this range stabilizes feeding in the extruder, and the melt moldability of the regrind layer of the molded article tends to be improved.

[0201] The apparent density can be controlled by adjusting the shape of the crushing blade of the crusher, the number of revolutions of the crushing blade, the crushing processing speed, the size of the openings of the mesh used, and the like.

[0202] The multilayer structure having a regrind layer is generally preferably a multilayer structure that further includes, in addition to the regrind layer, a layer containing a polyolefin resin, an adhesive layer, and an EVOH resin layer, where the EVOH resin layer means a layer containing an EVOH resin different from the regrind layer.

[0203] The thickness of each layer of the regrind layer-containing multilayer structure cannot be generalized depending on the layer configuration, type of polyolefin resin, intended use, container shape, required physical properties, etc., but the regrind layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. The EVOH resin layer is usually 5 to 500 μm, preferably 10 to 200 μm. The polyolefin resin layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. In this case, if an adhesive resin layer is present, the adhesive resin layer is usually 5 to 400 μm, preferably 10 to 150 μm.

[0204] The thickness ratio of the regrind layer to the polyolefin resin layer is usually 1 / 5 to 10 / 1, preferably 1 / 2 to 5 / 1, and the thickness ratio of the regrind layer to the EVOH resin layer is usually 1 / 1 to 100 / 1, preferably 5 / 1 to 20 / 1.

[0205] The regrind layer-containing multilayer structure can be used to obtain, for example, cup- or tray-shaped multilayer containers by the same method as the method for molding the multilayer structure. The resulting film, sheet, or stretched film-based bags and containers such as cups, trays, tubes, and bottles are useful as packaging materials or containers for a variety of items, including general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

[0206] <<Third Aspect>> The third aspect includes the following <III-1> to <III-20>. <III-1> A resin composition comprising a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, and wherein the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more. <III-2> The resin composition according to <III-1>, wherein the carbon-14 containing polypropylene resin (A) comprises a bio-polypropylene resin. <III-3> The resin composition according to <III-1> or <III-2>, excluding the following resin composition [α] from the resin composition: A resin composition [α] comprising a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) which differ in the proportion of ethylene structural units, and the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more, and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block of Period 4 of the Long Periodic Table. <III-4> The resin composition according to any one of <III-1> to <III-3>, wherein the carbon-14 containing polypropylene resin (A) is a homopolypropylene. <III-5> The resin composition according to any one of <III-1> to <III-4>, in which the carbon-14-containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having from 10 to 24 carbon atoms.<III-6> The resin composition according to any one of <III-1> to <III-5>, comprising at least an ethylene-vinyl alcohol copolymer (B1) having an ethylene structural unit content of 20 to 34 mol% and an ethylene-vinyl alcohol copolymer (B2) having an ethylene structural unit content of 35 to 60 mol%. <III-7> The resin composition according to any one of <III-1> to <III-6>, wherein the ethylene structural unit content in the ethylene-vinyl alcohol copolymer (B) is 20 to 60 mol%. <III-8> The resin composition according to any one of <III-1> to <III-7>, wherein the ethylene-vinyl alcohol copolymer (B) has an ethylene structural unit content of 0.01 to 15.0 mass% with respect to the entire resin composition. <III-9> The resin composition according to any one of <III-1> to <III-8>, wherein the carbon-14-containing polypropylene resin (A) has an ethylene structural unit content of 10 to 99 mass% with respect to the entire resin composition. <III-10> The resin composition according to any one of <III-1> to <III-9>, wherein the content of the acid-modified polyolefin resin (C) is 0.1% by mass or more and 20% by mass or less, based on the total mass of the resin composition. <III-11> A sheet comprising the resin composition according to any one of <III-1> to <III-10>. <III-12> A film comprising the resin composition according to any one of <III-1> to <III-10>. <III-13> A regrind layer comprising the resin composition according to any one of <III-1> to <III-10>. <III-14> A multilayer structure comprising the regrind layer according to <III-13>. <III-15> The multilayer structure according to <III-14>, further comprising a layer comprising a polyolefin resin. <III-16> The multilayer structure according to <III-14>, further comprising an adhesive resin layer. <III-17> The multilayer structure according to <III-14>, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer. <III-18> A molded article obtained by molding the multilayer structure according to <III-14>. <III-19> A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of <III-1> to <III-10>.<III-20> A method for producing a molded article, comprising a step of molding the multilayer structure according to <III-14>.

[0207] The present invention will be described below based on examples of modes for carrying out the third aspect, although the present invention is not limited to the embodiments described below.

[0208] <Resin composition (3)> A resin composition according to one example of an embodiment of the present invention (hereinafter referred to as "the present resin composition (3)") contains a polypropylene resin (A) containing 14 carbon atoms, an EVOH resin (B), and an acid-modified polyolefin resin (C), and the EVOH resin (B) contains two or more types of EVOH resins having different ethylene structural unit contents.

[0209] From the viewpoint of thermal stability, the resin composition (3) preferably does not contain the following resin composition [α]. Resin composition [α] comprises a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, the difference in the proportion of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) being 4 mol % or more, and the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block elements of Period 4 of the Long Periodic Table. Each component of the resin composition [α] is described below.

[0210] <Polypropylene resin (A) containing carbon-14> The polypropylene resin (A) containing carbon-14 used in the present resin composition (3) can be the same as the <Polypropylene resin (A) containing carbon-14> described in the first embodiment.

[0211] The resin composition (3) contains the polypropylene resin (A) containing 14 carbon atoms in a resin composition containing the EVOH resin (B), and therefore has superior thermal stability compared to resin compositions containing conventional petroleum-derived polypropylene resins.

[0212] The mechanism is thought to be as follows. It is known that petroleum-derived polypropylene resins are easily oxidized by heat, generating hydroperoxides and causing degradation reactions such as molecular weight reduction. One known method for suppressing such thermal degradation is to improve the thermal stability of polypropylene by adding a hindered phenol or other antioxidant. However, because such antioxidants tend to interact with EVOH resins, the thermal stability improvement effect is not fully achieved. In particular, when a large amount is added, the discoloration prevention effect of the antioxidant and mechanical properties tend to decrease. In such resin compositions containing polypropylene resin and EVOH resin as essential components, the use of a carbon-14-containing polypropylene resin (A) increases the bond energy due to the primary isotope effect. As a result, it is presumed that the decomposition of the carbon-14-containing polypropylene resin (A) itself is slowed, resulting in enhanced thermal stability. Furthermore, since thermal stability can be improved without affecting the EVOH resin (B), it is presumed that an excellent thermal stability improvement effect can be achieved.

[0213] The carbon-14-containing polypropylene resin (A) used in the resin composition (3) typically has a biobased content of 1 to 99%, preferably 5 to 95%, more preferably 10 to 90%, even more preferably 20 to 80%, and particularly preferably 30 to 70%. By adjusting the biobased content of the carbon-14-containing polypropylene resin (A) to fall within the above range, a resin composition with even better thermal stability can be obtained.

[0214] The content of the carbon-14 containing polypropylene resin (A) is typically 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total content of the resin composition (3). The upper limit is 99% by mass, preferably 95% by mass. The range of such a content is typically 10% by mass or more and 99% by mass or less. By setting the content of the carbon-14 containing polypropylene resin (A) within the above range, a resin composition with better thermal stability can be obtained.

[0215] <EVOH Resin (B)> The EVOH resin (B) used in the resin composition (3) comprises an EVOH resin (B1) and an EVOH resin (B2) which differ in the content of ethylene structural units, and the difference in the content of ethylene structural units between the EVOH resin (B1) and the EVOH resin (B2) is 4 mol % or more. EVOH resins are generally obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and are water-insoluble thermoplastic resins.

[0216] It is essential that the resin composition (3) contains two or more EVOH resins having different contents of ethylene structural units. By containing two or more EVOH resins having different contents of ethylene structural units, the EVOH resin having the lower content of ethylene structural units contributes to excellent gas barrier properties, while the EVOH resin having the higher content of ethylene structural units contributes to excellent moldability and mechanical properties, thereby enabling the resulting resin composition, multilayer structure, and molded article to achieve both gas barrier properties, moldability, and mechanical properties.

[0217] The polymerization of ethylene and vinyl ester monomers can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, and solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method.

[0218] The EVOH resin produced in this manner is mainly composed of structural units derived from ethylene and vinyl alcohol structural units, and usually contains a small amount of vinyl ester structural units that remain unsaponified.

[0219] Vinyl acetate is typically used as the vinyl ester monomer because of its commercial availability and the efficiency of impurity removal during production. Examples of vinyl ester monomers other than vinyl acetate include 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. Aliphatic vinyl esters having typically 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 alone or in combination of two or more types.

[0220] The EVOH resin may further contain structural units derived from the comonomers shown below within a range that does not impair the effects of the present invention (for example, 10 mol % or less of the EVOH resin).Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxy group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation 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-dibutyryloxy-2-methylenepropane. -hydroxyalkylvinylidene diacetates such as 2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salt, acrylamidopropyldimethylamine or its acid salt or its quaternary salt, etc. Acrylamides; methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or an acid salt or a quaternary salt thereof, and other methacrylamido groups; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochlorides, etc. vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl 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 may be used alone or in combination of two or more.

[0221] Among these, hydroxy group-containing α-olefins are preferred, and 3-butene-1,2-diol, 5-hexene-1,2-diol, and 2-methylenepropane-1,3-diol are particularly preferred. When the hydroxy group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in the side chains. Such EVOH resins having primary hydroxyl groups in the side chains, particularly EVOH resins having a 1,2-diol structure in the side chains, are preferred in that they maintain gas barrier properties while exhibiting good secondary moldability.

[0222] In the case of an EVOH resin having a primary hydroxyl group in a side chain, the content of structural units derived from a monomer having the primary hydroxyl group is usually 0.1 to 20 mol %, preferably 0.5 to 15 mol %, and particularly preferably 1 to 10 mol %.

[0223] The EVOH resin used in this embodiment may also be a "post-modified" EVOH resin, such as urethanized, acetalized, cyanoethylated, or oxyalkylenated.

[0224] When the post-modified EVOH resin is used, the modification rate is usually 10 mol % or less, and preferably 4 mol % or less. When the modification rate of the EVOH resin is equal to or less than the upper limit, thermal degradation is suppressed and the long-run property tends to be excellent.

[0225] As described above, the EVOH resin (B) contains two or more types of EVOH resins having different ethylene structural unit content ratios. The number of types of EVOH resins having different ethylene structural unit content ratios is usually 2 to 4, preferably 2 to 3, and particularly preferably 2. When the number of types is within the above range, productivity and economy tend to be good.

[0226] The number of EVOH resins containing different proportions of ethylene structural units in an EVOH resin can be determined from the number of peaks measured using a differential scanning calorimeter (DSC) described below. The proportions of each ethylene structural unit contained in the EVOH resin (B) can be determined, for example, by measuring the melting peak temperature and comparing it with the melting peak temperature of an EVOH resin whose proportion of ethylene structural units is known. From the above, the proportions of the ethylene structural units contained in two or more EVOH resins contained in the EVOH resin (B) can be calculated by measuring the melting peak temperature and the number of melting peaks of the EVOH resin. Furthermore, the melting peak temperature and the number of melting peaks of the EVOH resin (B) can be measured, and these results, together with the calculation method described below, can be used to calculate the proportions of the ethylene structural units contained in the two or more EVOH resins. 1 By combining and analyzing the results of the content ratio of the ethylene structural unit obtained by H-NMR measurement, the blending ratio of each EVOH resin having a different content ratio of the ethylene structural unit can be calculated. The melting peak temperature means the peak temperature measured by DSC when the temperature is increased from -50°C to 230°C at 10°C / min, decreased from 230°C to -50°C at 10°C / min, and then increased again from -50°C to 230°C at 10°C / min.

[0227] The EVOH resin (B) includes at least an EVOH resin (B1) and an EVOH resin (B2) having different ethylene structural unit contents.

[0228] The difference in the content of ethylene structural units between the EVOH resin (B1) and the EVOH resin (B2) in the EVOH resin (B) is 4 mol % or more, preferably 5 to 30 mol %, more preferably 6 to 25 mol %, and even more preferably 7 to 20 mol %. When the difference in the content of ethylene structural units is equal to or greater than the lower limit, thickness deviation and cracks tend to be less likely to occur during molding of the multilayer container, while when the difference is equal to or less than the upper limit, there is a tendency for the gas barrier property to be reduced and for the appearance to be improved.

[0229] From the viewpoints of gas barrier properties and container moldability, it is preferable that the content of ethylene structural units in the EVOH resin (B2) is higher than the content of ethylene structural units in the EVOH resin (B1).

[0230] From the viewpoints of gas barrier property and moldability into a container, it is preferable that the EVOH resin (B1) is an EVOH resin having the smallest content of ethylene structural units among the EVOH resins (B), and it is preferable that the EVOH resin (B2) is an EVOH resin having the largest content of ethylene structural units among the EVOH resins (B).

[0231] The ethylene content in the EVOH resin (B) can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene, and is 20 to 60 mol %, preferably 23 to 55 mol %, and particularly preferably 25 to 50 mol %. When the ethylene content is equal to or less than the upper limit, the EVOH resin tends to have excellent gas barrier properties, while when the ethylene content is equal to or greater than the lower limit, the EVOH resin tends to have good gas barrier properties and melt moldability under high humidity conditions.

[0232] The content of ethylene structural units in the EVOH resin (B1) is usually 20 to 34 mol%, preferably 20 to 32 mol%, more preferably 22 to 30 mol%, and even more preferably 25 to 30 mol%. When the content of ethylene structural units is equal to or greater than the lower limit, secondary processability and flexibility tend to be excellent, and when it is equal to or less than the upper limit, gas barrier properties tend to be good.

[0233] The content of ethylene structural units in the EVOH resin (B2) is usually 35 to 60 mol%, preferably 35 to 55 mol%, more preferably 35 to 50 mol%, and even more preferably 38 to 48 mol%. When the content of ethylene structural units is at least the lower limit, secondary processability and flexibility tend to be excellent, while when the content is at most the upper limit, gas barrier properties tend to be good.

[0234] In this specification, the content of ethylene structural units in the EVOH resin or resin composition is usually 1 It is measured by H-NMR measurement. For example,1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0235] The degree of saponification of the vinyl ester component in EVOH resin (B) can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) used when saponifying the ethylene-vinyl ester copolymer, and is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. If the degree of saponification is too low, the gas barrier properties, thermal stability, moisture resistance, etc. tend to decrease.

[0236] The saponification degree of the EVOH resin (B1) is usually 90 to 100 mol%, preferably 95 to 100 mol%, more preferably 99 to 100 mol%, and particularly preferably 99.5 to 100 mol%. When the saponification degree is within the above range, the gas barrier property, thermal stability, moisture resistance, etc. tend to be good.

[0237] The saponification degree of the EVOH resin (B2) is usually 90 to 99.7 mol%, preferably 93 to 99.5 mol%, and more preferably 95 to 99 mol%. When the saponification degree is equal to or greater than the lower limit, the gas barrier properties, thermal stability, moisture resistance, etc. tend to be good, and when the saponification degree is equal to or less than the upper limit, the secondary processability and flexibility tend to be good.

[0238] In this specification, the saponification degree of the EVOH resin is usually 1 It is measured by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using DMSO-d as the measurement solvent and setting the measurement temperature at 50°C.

[0239] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B) is usually 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 equal to or less than the upper limit, the film-forming property tends to be excellent, while when the MFR is equal to or greater than the lower limit, the viscosity tends not to be too high, and the melt extrudability tends to be good. The MFR is an index of the degree of polymerization of the EVOH resin, and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene and a vinyl ester monomer.

[0240] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B1) is usually 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 equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0241] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (B2) is usually 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 equal to or less than the upper limit, the mechanical strength of the molded product tends to be excellent, and when the MFR is equal to or more than the lower limit, the extrusion processability tends to be good.

[0242] In the combination of EVOH resin (B1) and EVOH resin (B2), the difference in MFR (210°C, load 2160 g) (ΔMFR) is preferably 5 g / 10 min or less, more preferably 1.5 g / 10 min or less, so that the flow properties of the resins during melt molding are comparable. The molecular weights of the respective EVOH resins are preferably adjusted so that the difference in MFR (ΔMFR) is 5 g / 10 min or less, more preferably 1.5 g / 10 min or less. In this specification, the MFR can be determined by measuring the flow rate of a sample passing through an orifice having a length of 8 mm and a hole diameter of 2.095 mm under conditions of a temperature of 210°C and a load of 2160 g, using an automatic melt flow rate tester (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0243] The density of the EVOH resin (B) is 0.8 to 2.55 g / cm for both the EVOH resin (B1) and the EVOH resin (B2). 3 When the density of the EVOH resin (B) is within the above range, stable extrusion molding tends to be possible. In this specification, the density can be measured based on JIS Z8807.

[0244] The mass content ratio (B1 / B2) of the EVOH resin (B1) to the EVOH resin (B2) is usually 99 / 1 to 30 / 70, preferably 95 / 5 to 30 / 70, more preferably 90 / 10 to 40 / 60, and particularly preferably 85 / 15 to 50 / 50. When the content ratio of the EVOH resin (B1) is equal to or higher than the lower limit, the gas barrier properties tend to be excellent, whereas when it is equal to or lower than the upper limit, uneven thickness and cracks tend to be less likely to occur during molding of the multilayer container.

[0245] The content of EVOH resin (B) in the resin composition (3) is not particularly limited, but is preferably 0.01 to 15.0 mass %, more preferably 0.05 to 13.0 mass %, even more preferably 0.1 to 9.9 mass %, particularly preferably 1.0 to 7.0 mass %, and most preferably 2.0 to 5.0 mass %, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0246] In the resin composition (3), the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) [(A) / (B)] is usually 10 / 90 to 99 / 1, preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 97 / 3, even more preferably 70 / 30 to 95 / 5, and particularly preferably 80 / 20 to 94 / 6. When the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) is within the above range, a resin composition having better thermal stability can be obtained.

[0247] In addition, in the present resin composition (3), the proportion of the total content of the EVOH resin (B) and the polypropylene resin (A) containing 14 carbon atoms in the entire resin composition is not particularly limited, but is usually 70 mass% or more, preferably 75 mass% or more, and more preferably 80 mass% or more.

[0248] <Acid-Modified Polyolefin Resin (C)> As the acid-modified polyolefin resin (C), the same as the <Acid-Modified Polyolefin Resin (C)> explained in the first embodiment can be used.

[0249] The content of the acid-modified polyolefin resin (C) in the resin composition (3) is usually 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 13% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 4% by mass or more and 9% by mass or less, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0250] <Other Components> Resins other than the polypropylene resin (A) containing 14 carbon atoms, the EVOH resin (B), and the acid-modified polyolefin resin (C) (e.g., petroleum-derived polypropylene resin, other types of resins), and optional additives (hereinafter, these are referred to as "other components") may be blended into the resin composition (3) according to various purposes, within the scope that does not significantly impair the effects of the present invention. Only one type of other component may be used, or two or more types may be used in any combination and ratio.

[0251] Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents.

[0252] When the present resin composition (3) contains the "other components," the total content of these components relative to the present resin composition (3) is usually 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. The lower limit is usually 0% by mass. The content is usually 0 to 30% by mass, etc.

[0253] <Method for Producing Resin Composition (3)> The resin composition (3) can be produced by mixing the essential components, carbon-14-containing polypropylene resin (A), EVOH resin (B), and acid-modified polyolefin resin (C), as well as the other components as needed. Examples of the mixing method include known methods such as dry blending, melt mixing using a single-screw extruder or twin-screw extruder to obtain a compound, solution mixing, and impregnation, and these can be combined in any desired manner. The carbon-14-containing polypropylene resin (A), EVOH resin (B), and acid-modified polyolefin resin (C) can be recycled resins obtained by pulverizing scraps of multilayer structures containing carbon-14-containing polypropylene resin layers, EVOH resin layers, and acid-modified polyolefin resin layers.

[0254] The resin composition (3) thus obtained is less likely to decompose under high temperature heating and has excellent thermal stability compared to conventional resin compositions obtained by combining an EVOH resin and a petroleum-derived polypropylene resin.

[0255] The biobased content of the resin composition (3) is usually 0.01 to 99%, preferably 0.1 to 90%, more preferably 1 to 80%, even more preferably 1 to 70%, and particularly preferably 10 to 60%. By setting the biobased content of the resin composition within this range, a resin composition with better thermal stability can be obtained.

[0256] The content of carbon-14 in the resin composition (3) is not particularly limited, but the ratio of carbon-14 to the total carbon in the resin composition is usually 1.0 × 10 -16 or more, 1.0 × 10 -14 The upper limit is usually 1.2 × 10 -12 is.

[0257] The melt flow rate (MFR) (210°C, load 2160 g) of the resin composition (3) is usually 0.1 to 100 g / 10 min, preferably 0.5 to 90 g / 10 min, more preferably 2 to 80 g / 10 min.

[0258] The water content of the resin composition (3) is usually 0.01 to 0.5% by mass, preferably 0.02 to 0.35% by mass, and more preferably 0.05 to 0.3% by mass.

[0259] The water content of the resin composition (3) is measured and calculated by the following method: The mass (W1) of the resin composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula: Water content (mass%) = [(W1 - W2) / W1] x 100

[0260] The present resin composition (3) is prepared as a resin composition in various forms, such as pellets or powder, and is provided as a material for various molded articles and multilayer structures. As described above, the present resin composition (3) has excellent thermal stability, so molded articles using the present resin composition (3) or multilayer structures having a layer using the present resin composition (3) are of excellent quality. In particular, in this embodiment, providing the present resin composition (3) as a material for melt molding is preferred, as the effects of the present invention tend to be more efficiently achieved.

[0261] [Molded Article] A molded article according to one embodiment of the present invention (hereinafter referred to as the "present molded article") is obtained by molding the present resin composition (3).

[0262] Examples of the shape of the present molded article include films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc. That is, the present resin composition (3) can be suitably used as any of films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc.

[0263] The molding method of the resin composition (3) is not particularly limited, and any molding method applicable to general resin compositions can be used, such as extrusion molding, blow molding, injection molding, thermoforming, etc.

[0264] [Multilayer structure] A multilayer structure according to one embodiment of the present invention (hereinafter referred to as "the multilayer structure") has at least one layer containing the present resin composition (3). The present multilayer structure can be further strengthened or imparted with other functions by being laminated with another substrate (hereinafter referred to as "substrate resin") containing a thermoplastic resin other than the present resin composition (3) as a main component.

[0265] Examples of the base resin include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene resins and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and the side chain); and resins obtained by converting these polyolefins into unsaturated carboxylic acids. Examples of the polyolefin resin include polyolefin resins in the broad sense including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with carboxylic acid or an ester thereof, 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, and aromatic or aliphatic polyketones.

[0266] Of these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred from the viewpoint of economy and productivity, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof.

[0267] The layer structure of the present multilayer structure 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, or b2 / b1 / a / b1 / a / b1 / b2, where a represents the resin composition layer and b represents the base resin layer (b1, b2, etc.). It is also possible to provide a recycled layer containing a mixture of the present resin composition (3) and the base resin, obtained by remelting and molding end portions or defective products generated during the manufacturing process of the multilayer structure. The total number of layers in the multilayer structure is typically 2 to 15, preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between each layer, if necessary.

[0268] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples of the carboxyl-containing modified polyolefin polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. One or a mixture of two or more selected from these can be used.

[0269] In the present multilayer structure, when an adhesive resin layer is used between the resin composition layer and the base resin layer, since the adhesive resin layers are located on both sides of the resin composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0270] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin).

[0271] The resin composition (3) can be laminated with the base resin (including through an adhesive resin layer) by a known method. Examples of such methods include melt-extrusion laminating the base resin onto a film, sheet, or the like of the resin composition (3), melt-extrusion laminating the resin composition (3) onto a base resin layer, co-extruding the resin composition with the base resin, dry-laminating the resin composition layer and the base resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and coating a solution of the resin composition on the base resin and then removing the solvent. Among these, from the standpoints of cost and the environment, the method of co-extruding the resin composition with the base resin is preferred.

[0272] The multilayer structure is optionally subjected to a (heat) stretching treatment. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0273] For the purpose of imparting dimensional stability, heat setting may be carried out after the stretching treatment. Heat setting can be carried out by known means, for example, by heat treating the stretched film while maintaining it in a tensile state, usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds. When the multilayer stretched film obtained from the present resin composition (3) is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0274] In some cases, the multilayer structure can be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0275] The thickness of the multilayer structure (including a stretched structure), as well as the thickness of the resin composition layer, substrate resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generally determined depending on the layer configuration, type of substrate resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the multilayer structure (including a stretched structure) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, and particularly preferably 50 to 2,000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm. The substrate resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and particularly preferably 20 to 1,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

[0276] Furthermore, the thickness ratio of the resin composition layer to the substrate resin layer (resin composition layer / substrate resin layer), when there are multiple layers of each type, is typically 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60. Furthermore, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer), when there are multiple layers of each type, is typically 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0277] In the present multilayer structure, the layer containing the present resin composition (3) is preferably a layer (regrind layer) formed using the present resin composition (3) (= recycled resin composition) containing a polypropylene resin layer containing 14 carbon atoms, an EVOH resin layer containing two or more EVOH resins having different ethylene structural unit content ratios, and an acid-modified polyolefin resin layer. Such a multilayer structure having a regrind layer will be described below.

[0278] The recycled materials of the multilayer structure containing a polypropylene resin layer containing 14 carbon atoms, an EVOH resin layer containing two or more EVOH resins having different ethylene structural unit content ratios, and an acid-modified polyolefin resin layer used to obtain the regrind layer are scraps, unnecessary parts such as end parts, defective products, and waste after the molded body has been used for various purposes, collected during the production process. These recycled materials can be reused to prepare the present resin composition (3), which can be used to obtain the regrind layer.

[0279] To obtain the regrind layer, for example, the recycled material (a composition containing a carbon-14 polypropylene resin (A), an EVOH resin layer containing two or more EVOH resins differing in the content of ethylene structural units, and an acid-modified polyolefin resin (C)) is appropriately combined with other optional components, and, as necessary, additional carbon-14 polypropylene resin (A), an EVOH resin layer containing two or more EVOH resins differing in the content of ethylene structural units, and an acid-modified polyolefin resin (C) are added. By uniformly mixing these components, the present resin composition (3), which is a recycled resin composition, is obtained. The present resin composition (3) is then melt-molded and co-extruded to obtain the present multilayer structure having a regrind layer.

[0280] In order to re-submit a recovered multilayer structure comprising a polypropylene resin layer containing carbon-14, an EVOH resin layer containing two or more EVOH resins differing in the content of ethylene structural units, and an acid-modified polyolefin resin layer to melt molding in an extruder or the like, it is preferable to pulverize the recovered material. The pulverization can be carried out using a known pulverizer. The shape and particle size of the pulverized material, as measured in accordance with the "5.3 Apparent Density" test method of JIS-K6891, are typically 0.25 to 0.85 g / mL, preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. Having an apparent density equal to or greater than the lower limit of this range improves dispersion of the EVOH resin in the regrind layer, and the resulting molded article tends to have excellent melt moldability and mechanical properties. Having an apparent density equal to or less than the upper limit of this range stabilizes feeding in the extruder, and the melt moldability of the regrind layer of the molded article tends to be improved.

[0281] The apparent density can be controlled by adjusting the shape of the crushing blade of the crusher, the number of revolutions of the crushing blade, the crushing processing speed, the size of the openings of the mesh used, and the like.

[0282] The multilayer structure having a regrind layer is generally preferably a multilayer structure that further includes, in addition to the regrind layer, a layer containing a polyolefin resin, an adhesive layer, and an EVOH resin layer, where the EVOH resin layer means a layer containing an EVOH resin different from the regrind layer.

[0283] The thickness of each layer of the regrind layer-containing multilayer structure cannot be generalized depending on the layer configuration, type of polyolefin resin, intended use, container shape, required physical properties, etc., but the regrind layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. The EVOH resin layer is usually 5 to 500 μm, preferably 10 to 200 μm. The polyolefin resin layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. In this case, if an adhesive resin layer is present, the adhesive resin layer is usually 5 to 400 μm, preferably 10 to 150 μm.

[0284] The thickness ratio of the regrind layer to the polyolefin resin layer is usually 1 / 5 to 10 / 1, preferably 1 / 2 to 5 / 1, and the thickness ratio of the regrind layer to the EVOH resin layer is usually 1 / 1 to 100 / 1, preferably 5 / 1 to 20 / 1.

[0285] The regrind layer-containing multilayer structure can be used to obtain, for example, cup- or tray-shaped multilayer containers by the same method as used to mold the multilayer structure.

[0286] The films, sheets, and bags made of the stretched films obtained as described above, and containers such as cups, trays, tubes, and bottles are useful as various packaging materials and containers for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, and the like.

[0287] <<Fourth Aspect>> The fourth aspect includes the following items <IV-1> to <IV-20>. <IV-1> A resin composition containing a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), and an ethylene-α-olefin copolymer (F). <IV-2> The resin composition according to <IV-1>, in which the carbon-14 containing polypropylene resin (A) includes a bio-polypropylene resin. <IV-3> The resin composition according to <IV-1> or <IV-2>, in which the following resin composition [α] is excluded from the resin composition. Resin composition [α] includes a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an ethylene-α-olefin copolymer (F), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) that is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d block of Period 4 of the Long Form Periodic Table. <IV-4> The resin composition according to any one of <IV-1> to <IV-3>, wherein the carbon-14 containing polypropylene resin (A) is a homopolypropylene. <IV-5> The resin composition according to any one of <IV-1> to <IV-4>, wherein the carbon-14 containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having from 10 to 24 carbon atoms. <IV-6> The resin composition according to any one of <IV-1> to <IV-5>, wherein the ethylene-vinyl alcohol copolymer (B) contains 20 to 60 mol% of ethylene structural units. <IV-7> The resin composition according to any one of <IV-1> to <IV-6>, wherein the ethylene-vinyl alcohol copolymer (B) contains 0.01 to 15.0 mass% of the total resin composition. <IV-8> The resin composition according to any one of <IV-1> to <IV-7>, wherein the carbon-14 containing polypropylene resin (A) contains 10 to 99 mass% of the total resin composition. <IV-9> The resin composition according to any one of <IV-1> to <IV-8>, wherein the content of the acid-modified polyolefin resin (C) is 0.1% by mass or more and 20% by mass or less, based on the entire resin composition.<IV-10> The resin composition according to any one of <IV-1> to <IV-9>, wherein the content of the ethylene-α-olefin copolymer (F) is 0.01% by mass or more and 35% by mass or less, based on the total mass of the resin composition. <IV-11> A sheet comprising the resin composition according to any one of <IV-1> to <IV-10>. <IV-12> A film comprising the resin composition according to any one of <IV-1> to <IV-10>. <IV-13> A regrind layer comprising the resin composition according to any one of <IV-1> to <IV-10>. <IV-14> A multilayer structure comprising the regrind layer according to <IV-13>. <IV-15> The multilayer structure according to <IV-14>, further comprising a layer comprising a polyolefin resin. <IV-16> The multilayer structure according to <IV-14>, further comprising an adhesive resin layer. <IV-17> The multilayer structure according to <IV-14>, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer. <IV-18> A molded article obtained by molding the multilayer structure according to <IV-14>. <IV-19> A method for producing a multilayer structure, comprising a step of co-extruding the resin composition according to any one of <IV-1> to <IV-10>. <IV-20> A method for producing a molded article, comprising a step of molding the multilayer structure according to <IV-14>.

[0288] The present invention will be described below based on examples of modes for carrying out the fourth aspect, although the present invention is not limited to the embodiments described below.

[0289] <Resin Composition (4)> A resin composition according to an embodiment of the present invention (hereinafter referred to as "the present resin composition (4)") contains a carbon-14-containing polypropylene resin (A), an EVOH resin (B), an acid-modified polyolefin resin (C), and an ethylene-α-olefin copolymer (F). From the viewpoint of thermal stability, the present resin composition (4) preferably does not contain the following resin composition [α]. Resin composition [α] contains a carbon-14-containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an ethylene-α-olefin copolymer (F), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) that is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d-block elements of Period 4 of the Long Periodic Table. Each component is described below.

[0290] <Carbon-14-containing polypropylene resin (A)> The carbon-14-containing polypropylene resin (A) used in the resin composition (4) can be the same as the carbon-14-containing polypropylene resin (A) described in the first embodiment.

[0291] The resin composition (4) contains a biomass-derived (carbon-14 containing) polypropylene resin (A) in a resin composition containing an EVOH resin (B), and therefore has superior thermal stability compared to resin compositions containing conventional petroleum-derived polypropylene resins.

[0292] The mechanism is thought to be as follows. It is known that petroleum-derived polypropylene resins are easily oxidized by heat, generating hydroperoxides and causing degradation reactions such as molecular weight reduction. One known method for suppressing such thermal degradation is to improve the thermal stability of polypropylene by adding a hindered phenol or other antioxidant. However, because such antioxidants tend to interact with EVOH resins, the thermal stability improvement effect is not fully achieved. In particular, when a large amount is added, the discoloration prevention effect of the antioxidant and mechanical properties tend to decrease. In such resin compositions containing polypropylene resin and EVOH resin as essential components, the use of a carbon-14-containing polypropylene resin (A) increases the bond energy due to the primary isotope effect. As a result, it is presumed that the decomposition of the carbon-14-containing polypropylene resin (A) itself is slowed, resulting in enhanced thermal stability. Furthermore, since thermal stability can be improved without affecting the EVOH resin (B), it is presumed that an excellent thermal stability improvement effect can be achieved.

[0293] The carbon-14-containing polypropylene resin (A) used in the resin composition (4) typically has a biobased content of 1 to 99%, preferably 5 to 95%, more preferably 10 to 90%, even more preferably 20 to 80%, and particularly preferably 30 to 70%. By adjusting the biobased content of the carbon-14-containing polypropylene resin (A) to fall within the above range, a resin composition with even better thermal stability can be obtained.

[0294] The content of the carbon-14 containing polypropylene resin (A) is typically 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total content of the resin composition (4). The upper limit is typically 99% by mass, preferably 98% by mass. The range of such a content is typically 10% by mass or more and 99% by mass or less. By setting the content of the carbon-14 containing polypropylene resin (A) within the above range, a resin composition with better thermal stability can be obtained.

[0295] <EVOH Resin (B)> The EVOH resin (B) is usually a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and the same EVOH resin (B) as the <EVOH resin (B)> described in the first embodiment can be used.

[0296] The content of the EVOH resin (B) in the resin composition (4) is preferably 0.01 to 15.0 mass%, more preferably 0.05 to 13.0 mass%, even more preferably 3.0 to 12.5 mass%, particularly preferably 4.0 to 12.0 mass%, and most preferably 7.0 to 11.0 mass%, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0297] In the resin composition (4), the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) [(A) / (B)] is usually 10 / 90 to 99 / 1, preferably 30 / 70 to 98 / 2, more preferably 50 / 50 to 97 / 3, even more preferably 70 / 30 to 95 / 5, and particularly preferably 80 / 20 to 94 / 6. When the mass ratio of the carbon-14 containing polypropylene resin (A) to the EVOH resin (B) is within the above range, a resin composition having better thermal stability can be obtained.

[0298] In addition, in the present resin composition (4), the proportion of the total content of the EVOH resin (B) and the polypropylene resin (A) containing 14 carbon atoms in the entire resin composition is not particularly limited, but is usually 70 mass% or more, preferably 75 mass% or more, and more preferably 80 mass% or more.

[0299] In the present resin composition (4), when the EVOH resin (B) contains the EVOH resins (B1) and (B2), the mass ratio (B1 / B2) of the EVOH resin (B1) to the EVOH resin (B2) is preferably 99 / 1 to 30 / 70, more preferably 95 / 5 to 30 / 70, even more preferably 90 / 10 to 40 / 60, and particularly preferably 85 / 15 to 50 / 50.

[0300] <Acid-modified polyolefin resin (C)> The resin composition (4) contains an acid-modified polyolefin resin (C) (excluding the acid-modified ethylene-α-olefin copolymer (F2) described below, the same applies hereinafter). As the acid-modified polyolefin resin (C), the same as the <Acid-modified polyolefin resin (C)> described in the first embodiment can be used.

[0301] The content of the acid-modified polyolefin resin (C) in the resin composition (4) is usually 0.1% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 13% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 4% by mass or more and 9% by mass or less, based on the total mass of the resin composition. When this value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0302] <Ethylene-α-olefin copolymer (F)> The ethylene-α-olefin copolymer (F) used in the resin composition (4) is a known resin obtained by copolymerizing ethylene as the main component with an α-olefin having 3 to 20 carbon atoms. However, among ethylene-α-olefin copolymers, those having a vinyl alcohol structural unit are classified as EVOH resin (B) and are not considered to be ethylene-α-olefin copolymers (F). Ethylene-α-olefin copolymers (F) are broadly classified into unmodified ethylene-α-olefin copolymers (F1) that have not been modified with acid and acid-modified ethylene-α-olefin copolymers (F2) that have been modified with acid. These copolymers can be used alone or in combination of two or more. Multilayer structures and molded articles obtained by incorporating the ethylene-α-olefin copolymer (F) have excellent flexibility and impact resistance.

[0303] [Unmodified ethylene-α-olefin copolymer (F1)] The unmodified ethylene-α-olefin copolymer (F1) is not particularly limited, and examples thereof include an ethylene-propylene copolymer (EP), an ethylene-butylene copolymer (EB), etc. Among these, from the viewpoint of superior flexibility and impact resistance, an ethylene-propylene copolymer (EP), an ethylene-butylene copolymer (EB), and an ethylene-octene copolymer (EO) are preferred, and an ethylene-butylene copolymer (EB) is more preferred.

[0304] The unmodified ethylene-α-olefin copolymer (F1) usually has a density of 0.80 to 0.96 g / cm 3 is preferably 0.82 to 0.92 g / cm 3 , particularly preferably 0.85 to 0.90 g / cm 3 is.

[0305] The unmodified ethylene-α-olefin copolymer (F1) has a melt flow rate (MFR) of usually 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 1 to 25 g / 10 min, and particularly preferably 1.5 to 10 g / 10 min, under conditions of 210°C and a load of 2160 g.

[0306] [Acid-Modified Ethylene-α-Olefin Copolymer (F2)] The acid-modified ethylene-α-olefin copolymer (F) is an ethylene-α-olefin copolymer having carboxy groups in either or both of the main chain and side chain of the unmodified ethylene-α-olefin copolymer (F1). Such acid-modified ethylene-α-olefin copolymer (F2) can be obtained by copolymerizing the unmodified ethylene-α-olefin copolymer (F1) by replacing some of the monomers constituting the unmodified ethylene-α-olefin copolymer (F1) with α,β-unsaturated carboxylic acid or anhydride monomers thereof, or by introducing α,β-unsaturated carboxylic acid or anhydride thereof into some of the side chains by a graft reaction such as radical addition.

[0307] Specific examples of the α,β-unsaturated carboxylic acid or anhydride thereof include α,β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α,β-unsaturated dicarboxylic acids such as maleic acid, succinic acid, itaconic acid, and phthalic acid; α,β-unsaturated monocarboxylic acid esters such as glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, and hydroxymethyl methacrylate; and α,β-unsaturated dicarboxylic acid anhydrides such as maleic anhydride, succinic anhydride, itaconic anhydride, and phthalic anhydride. These can be used alone or in combination of two or more. Of these, α,β-unsaturated dicarboxylic acid anhydrides are preferred, and maleic anhydride is particularly preferred.

[0308] The acid-modified ethylene-α-olefin copolymer (F2) can be a resin having a carboxy group in either the main chain or the side chain, or both, of the ethylene-α-olefin copolymer used in the unmodified ethylene-α-olefin copolymer (F1). As the acid-modified ethylene-α-olefin copolymer (F2), a carboxy group-containing ethylene-propylene copolymer (EP), a carboxy group-containing ethylene-butene copolymer (EB), or a carboxy group-containing ethylene-octene copolymer (EO) is preferred, from the viewpoint of efficiently achieving the effects of the present invention, with the carboxy group-containing ethylene-butene copolymer (EB) and the carboxy group-containing ethylene-octene copolymer (EO) being more preferred, and the maleic anhydride-modified ethylene-octene copolymer (EO) being particularly preferred.

[0309] The acid value of the acid-modified ethylene-α-olefin copolymer (F2) is preferably 50 mgKOH / g or less. When the acid value is equal to or less than the upper limit, the number of reaction sites with hydroxyl groups in the EVOH resin (B) is reduced, the production of highly polymerized products is suppressed during the melt-kneading process, stability during extrusion processing is improved, and a good molded product tends to be more easily obtained. The upper limit of the acid value is more preferably 30 mgKOH / g or less, and even more preferably 20 mgKOH / g or less. On the other hand, the lower limit of the acid value is preferably 1 mgKOH / g or more, and more preferably 2 mgKOH / g or more. When the acid value is equal to or more than the lower limit, compatibility with the EVOH resin (B) is improved, and the amount of resin adhering to the die during extrusion processing tends to be reduced.

[0310] The density of the acid-modified ethylene-α-olefin copolymer (F2) is usually 0.85 to 0.96 g / cm 3 and preferably 0.85 to 0.92 g / cm 3 , more preferably 0.85 to 0.9 g / cm 3 By using such a low-density acid-modified ethylene-α-olefin copolymer (F), molded articles and multilayer structures having particularly excellent flex resistance can be obtained.

[0311] The melt flow rate (MFR) of the acid-modified ethylene-α-olefin copolymer (F2) is usually 0.01 to 150 g / 10 min, preferably 0.1 to 50 g / 10 min, more preferably 1 to 25 g / 10 min, and even more preferably 1.5 to 10 g / 10 min, under conditions of 210°C and a load of 2160 g.

[0312] The content of the ethylene-α-olefin copolymer (F) in the resin composition (4) is usually 0.01% by mass or more and 35% by mass or less, preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.15% by mass or more and 25% by mass or less, even more preferably 0.2% by mass or more and 20% by mass or less, and particularly preferably 1% by mass or more and 15% by mass or less, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0313] The content of the unmodified ethylene-α-olefin copolymer (F1) in the resin composition (4) is usually 0.001% by mass or more and 30% by mass or less, preferably 0.01% by mass or more and 25% by mass or less, more preferably 0.15% by mass or more and 20% by mass or less, even more preferably 0.1% by mass or more and 15% by mass or less, and particularly preferably 0.2% by mass or more and 10% by mass or less, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0314] The content of the acid-modified ethylene-α-olefin copolymer (F2) in the resin composition (4) is usually 0.1% by mass or more and 35% by mass or less, preferably 0.5% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 25% by mass or less, even more preferably 1.5% by mass or more and 20% by mass or less, and particularly preferably 2% by mass or more and 15% by mass or less, based on the total mass of the resin composition. When the value is within the above range, the effects of the present invention tend to be more effectively obtained.

[0315] <Other Components> Resins other than the polypropylene resin (A) containing 14 carbon atoms, the EVOH resin (B), the ethylene-α-olefin copolymer (F), and the acid-modified polyolefin resin (C) (e.g., petroleum-derived polypropylene resin, other types of resins), and optional additives (hereinafter, these are referred to as "other components") may be blended into the resin composition (4) according to various purposes, within the scope of not significantly impairing the effects of the present invention. Only one type of other component may be used, or two or more types may be used in any combination and ratio.

[0316] Examples of the additives include antioxidants, ultraviolet absorbers, plasticizers, lubricants, fillers, and antistatic agents.

[0317] When the present resin composition (4) contains the "other components," the total content of these components relative to the present resin composition (4) is usually 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. The lower limit is usually 0% by mass. The content is usually 0 to 30% by mass, etc.

[0318] <Method for Producing Resin Composition (4)> The resin composition (4) can be produced by mixing the essential components, carbon-14-containing polypropylene resin (A), EVOH resin (B), acid-modified polyolefin resin (C), and ethylene-α-olefin copolymer (F), as well as other components. Examples of the mixing method include known methods such as dry blending, melt mixing using a single-screw extruder or twin-screw extruder to obtain a compound, solution mixing, and impregnation, and these methods can be combined in any desired manner. The carbon-14-containing polypropylene resin (A), EVOH resin (B), acid-modified polyolefin resin (C), and ethylene-α-olefin copolymer (F) can be recycled resins obtained by pulverizing scraps of multilayer structures containing carbon-14-containing polypropylene resin layers, EVOH resin layers, acid-modified polyolefin resin layers, and ethylene-α-olefin copolymers.

[0319] The resin composition (4) thus obtained is less likely to decompose under high temperature heating and has excellent thermal stability compared to conventional resin compositions obtained by combining an EVOH resin and a petroleum-derived polypropylene resin.

[0320] The biobased content of the resin composition (4) is usually 0.01 to 99%, preferably 0.1 to 90%, more preferably 1 to 80%, even more preferably 1 to 70%, and particularly preferably 10 to 60%. By setting the biobased content of the resin composition within this range, a resin composition with better thermal stability can be obtained.

[0321] The content of carbon-14 in the resin composition (4) is not particularly limited, but the ratio of carbon-14 to the total carbon in the resin composition is usually 1.0 × 10 -16 or more, 1.0 × 10 -14 The upper limit is usually 1.2 × 10 -12 is.

[0322] The melt flow rate (MFR) (210°C, load 2160 g) of the resin composition (4) is usually 0.1 to 100 g / 10 min, preferably 0.5 to 90 g / 10 min, more preferably 2 to 80 g / 10 min.

[0323] The water content of the resin composition (4) is usually 0.01 to 0.5% by mass, preferably 0.02 to 0.35% by mass, and more preferably 0.05 to 0.3% by mass.

[0324] The water content of the resin composition (4) is measured and calculated by the following method: The mass (W1) of the resin composition before drying is weighed on an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then cooled in a desiccator for 30 minutes, after which the mass (W2) is weighed and calculated using the following formula: Water content (mass%) = [(W1 - W2) / W1] x 100

[0325] The present resin composition (4) is prepared as a resin composition in various forms, such as pellets or powder, and is provided as a material for various molded articles and multilayer structures. As described above, the present resin composition (4) has excellent thermal stability, so molded articles using the present resin composition (4) or multilayer structures having a layer using the present resin composition (4) are of excellent quality. In particular, in this embodiment, providing the present resin composition (4) as a material for melt molding is preferred, as this tends to more efficiently achieve the effects of the present invention.

[0326] [Molded Article] A molded article according to one embodiment of the present invention (hereinafter referred to as the "present molded article") is obtained by molding the present resin composition (4).

[0327] Examples of the shape of the present molded article include films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc. That is, the present resin composition (4) can be suitably used as any of films, sheets, tapes, cups, trays, tubes, bottles, containers, pipes, filaments, irregular cross-section extrusions, various irregularly shaped articles, etc.

[0328] The molding method of the resin composition (4) is not particularly limited, and any molding method applicable to general resin compositions can be used, such as extrusion molding, blow molding, injection molding, thermoforming, etc.

[0329] [Multilayer Structure] A multilayer structure according to one embodiment of the present invention (hereinafter referred to as the "multilayer structure") has at least one layer containing the resin composition (4). The multilayer structure can be further strengthened or imparted with other functions by laminating it with another substrate (hereinafter referred to as the "base resin") whose main component is a thermoplastic resin other than the resin composition (4). In this specification, the term "main component" refers to the component that accounts for the largest proportion in the target object, and typically represents 50% by mass or more of the target object, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and especially preferably 90% by mass or more, or even 100% by mass. The content range is, for example, 50 to 100% by mass.

[0330] Examples of the base resin include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and the side chain); and polyolefins containing unsaturated carboxylic acid. Examples of the polyolefin resin include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with an acid or an ester thereof, 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, and aromatic or aliphatic polyketones.

[0331] Of these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins are preferred from the viewpoint of economy and productivity, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof.

[0332] The layer structure of the present multilayer structure 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, or b2 / b1 / a / b1 / a / b1 / b2, where a represents the resin composition layer and b represents the base resin layer (b1, b2, etc.). It is also possible to provide a recycled layer containing a mixture of the present resin composition (4) and the base resin, obtained by remelting and molding end portions or defective products generated during the manufacturing process of the multilayer structure. The total number of layers in the multilayer structure is typically 2 to 15, preferably 3 to 10. In the above layer structure, an adhesive resin layer containing an adhesive resin may be interposed between each layer, if necessary.

[0333] Known adhesive resins can be used, and may be selected appropriately depending on the type of thermoplastic resin used in the base resin layer "b." Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples of the carboxyl-containing modified polyolefin polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. One or a mixture of two or more selected from these can be used.

[0334] In the present multilayer structure, when an adhesive resin layer is used between the resin composition layer and the base resin layer, since the adhesive resin layers are located on both sides of the resin composition layer, it is preferable to use an adhesive resin with excellent hydrophobicity.

[0335] The base resin and adhesive resin may contain conventionally known plasticizers, fillers, clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes, etc., within a range that does not impair the spirit of the present invention (for example, 30% by mass or less, preferably 10% by mass or less, based on the total mass of the resin).

[0336] The resin composition (4) can be laminated with the base resin (including through an adhesive resin layer) by a known method. Examples of such methods include melt-extrusion laminating the base resin onto a film, sheet, or the like of the resin composition (4), melt-extrusion laminating the resin composition (4) onto a base resin layer, co-extruding the resin composition with the base resin, dry-laminating the resin composition layer and the base resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound, and coating a solution of the resin composition on the base resin and then removing the solvent. Among these, from the standpoints of cost and the environment, the method of co-extruding the resin composition with the base resin is preferred.

[0337] The multilayer structure is optionally subjected to a (heat) stretching treatment. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming, or the like, whichever provides a higher stretch ratio. The stretching temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

[0338] For the purpose of imparting dimensional stability, heat setting may be carried out after the stretching treatment. Heat setting can be carried out by known means, for example, by heat treating the stretched film while maintaining it in a tensile state, usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds. When the multilayer stretched film obtained from the present resin composition (4) is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0339] In some cases, the multilayer structure can be used to produce cup- or tray-shaped multilayer containers. In this case, a drawing method is typically used, specifically vacuum forming, pressure forming, vacuum-pressure forming, plug-assisted vacuum-pressure forming, etc. Furthermore, blow molding is used to produce tube- or bottle-shaped multilayer containers (laminate structure) from a multilayer parison (a hollow tubular preform before blowing). Specific examples include extrusion blow molding (double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion-type cold parison biaxial stretch blow molding, injection-type cold parison biaxial stretch blow molding, injection-molding in-line biaxial stretch blow molding, etc.). The resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0340] The thickness of the multilayer structure (including a stretched structure), as well as the thickness of the resin composition layer, substrate resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generally determined depending on the layer configuration, type of substrate resin, type of adhesive resin, intended use, packaging form, required physical properties, etc., but the thickness of the multilayer structure (including a stretched structure) is usually 10 to 5,000 μm, preferably 30 to 3,000 μm, more preferably 50 to 2,000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, more preferably 5 to 200 μm. The substrate resin layer is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, more preferably 20 to 1,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, more preferably 3 to 100 μm.

[0341] Furthermore, the thickness ratio of the resin composition layer to the base resin layer in the multilayer structure (resin composition layer / base resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and more preferably 10 / 90 to 40 / 60. Furthermore, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and more preferably 50 / 50 to 90 / 10.

[0342] In the present multilayer structure, the layer containing the present resin composition (4) is preferably a layer (regrind layer) formed using the present resin composition (4) (= recycled resin composition) containing a polypropylene resin layer containing carbon 14, an EVOH resin layer, an acid-modified polyolefin resin layer, or an ethylene-α-olefin copolymer. Such a multilayer structure having a regrind layer will be described below.

[0343] The recycled materials of the multilayer structure containing a carbon-14-containing polypropylene resin layer, an EVOH resin layer, an acid-modified polyolefin resin layer, and an ethylene-α-olefin copolymer used to obtain the regrind layer are scraps, unnecessary parts such as end parts, and defective products collected during the production of the multilayer structure, or waste after the molded body has been used for various purposes. These recycled materials can be reused to prepare the present resin composition (4), which can be used to obtain the regrind layer.

[0344] To obtain the regrind layer, for example, the recycled material (a composition containing a carbon-14-containing polypropylene resin (A), an EVOH resin (B), an acid-modified polyolefin resin (C), and an ethylene-α-olefin copolymer (F)) is appropriately combined with other optional components, and, if necessary, additional carbon-14-containing polypropylene resin (A), an EVOH resin (B), an acid-modified polyolefin resin (C), and an ethylene-α-olefin copolymer (F) are added. By uniformly mixing these components, the present resin composition (4), which is a recycled resin composition, is obtained. Then, by performing a process of melt-molding and co-extrusion using the present resin composition (4), the present multilayer structure having a regrind layer can be obtained.

[0345] In order to re-submit the recovered product of the multilayer structure containing the carbon-14-containing polypropylene resin layer, the EVOH resin layer, the acid-modified polyolefin resin layer, and the ethylene-α-olefin copolymer to melt molding in an extruder or the like, it is preferable to pulverize the recovered product. The pulverization can be carried out using a known pulverizer. The shape and particle size of the pulverized product, as measured in accordance with the "5.3 Apparent Density" test method of JIS-K6891, are typically 0.25 to 0.85 g / mL, preferably 0.3 to 0.7 g / mL, and particularly preferably 0.35 to 0.6 g / mL. Having an apparent density equal to or greater than the lower limit of this range improves dispersion of the EVOH resin in the regrind layer, and the resulting molded article tends to have excellent melt moldability and mechanical properties. Having an apparent density equal to or less than the upper limit of this range stabilizes feeding in the extruder, and the melt moldability of the regrind layer of the molded article tends to be improved.

[0346] The apparent density can be controlled by adjusting the shape of the crushing blade of the crusher, the number of revolutions of the crushing blade, the crushing processing speed, the size of the openings of the mesh used, and the like.

[0347] The multilayer structure having a regrind layer is generally preferably a multilayer structure that further includes, in addition to the regrind layer, a layer containing a polyolefin resin, an adhesive layer, and an EVOH resin layer, where the EVOH resin layer means a layer containing an EVOH resin different from the regrind layer.

[0348] The thickness of each layer of the regrind layer-containing multilayer structure cannot be generalized depending on the layer configuration, type of polyolefin resin, intended use, container shape, required physical properties, etc., but the regrind layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. The EVOH resin layer is usually 5 to 500 μm, preferably 10 to 200 μm. The polyolefin resin layer is usually 5 to 5,000 μm, preferably 30 to 1,000 μm. In this case, if an adhesive resin layer is present, the adhesive resin layer is usually 5 to 400 μm, preferably 10 to 150 μm.

[0349] The thickness ratio of the regrind layer to the polyolefin resin layer is usually 1 / 5 to 10 / 1, preferably 1 / 2 to 5 / 1, and the thickness ratio of the regrind layer to the EVOH resin layer is usually 1 / 1 to 100 / 1, preferably 5 / 1 to 20 / 1.

[0350] The regrind layer-containing multilayer structure can be used to obtain, for example, cup- or tray-shaped multilayer containers by the same method as used to mold the multilayer structure.

[0351] The films, sheets, and bags made of the stretched films obtained as described above, and containers such as cups, trays, tubes, and bottles are useful as various packaging materials and containers for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, and the like.

[0352] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" refer to mass standards. The reference examples in the second to fourth aspects below are intended for comparative study within each aspect, and are not comparative examples of the present invention related to the first aspect.

[0353] <<First Aspect>> Prior to the Examples, the following components were prepared.

[0354] [Polypropylene resin (A)] Carbon-14 containing polypropylene resin (A1): homopolypropylene resin containing carbon-14 (manufactured by LyondellBasell, HP640J), MFR (230°C, load 2160 g) 3.2 g / 10 min, biomass content 40% or more, carbon-14 content 0.4 ppt or more Petroleum-derived polypropylene resin (A'1): polypropylene resin (manufactured by Japan Polypropylene, FY6), MFR (230°C, load 2160 g) 2.4 g / 10 min

[0355] [EVOH Resin (B)] EVOH Resin (B1): Ethylene structural unit content 29 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min, density 1.21 g / cm 3 EVOH resin (B2): ethylene structural unit content 44 mol%, MFR (230°C, load 2160 g) 3.5 g / 10 min, density 1.14 g / cm 3 , Saponification degree 99.9 mol%

[0356] [Acid-modified polyolefin resin (C)] Acid-modified polyolefin resin (C1): Maleic acid graft-modified polyolefin resin (manufactured by Mitsubishi Chemical Corporation, Modic (registered trademark) P674V), MFR (230°C, load 2160 g) 3.4 g / 10 min, density 0.890 g / cm 3 Acid-modified ethylene-α-olefin copolymer (C2): maleic anhydride-modified ethylene-butene copolymer ("MA8510" manufactured by Mitsui Chemicals, Inc.), MFR (230 ° C, load 2160 g) 2.4 g / 10 min, density 0.885 g / cm 3

[0357] Example I-1 85.1% of a carbon-14 containing polypropylene resin (A1), 9.9% of an EVOH resin (B1), and 5% of an acid-modified polyolefin (C1) were dry-blended together, and then fed to a twin-screw kneader at a rate of 12 kg / hour using a mass feeder. The mixture was then strand-cut using a drum pelletizer to prepare a pelletized resin composition. The kneading conditions were as follows: [Kneading Conditions] Twin-screw extruder: diameter 20 mm, L / D=48 (manufactured by Toshiba Machine Co., Ltd.) Extruder temperature settings: C1 / C2 / C3 / C4 / C5 / C6 / H=100 / 180 / 210 / 210 / 230 / 230 / 230 Screw rotation speed: 460 rpm Take-up speed: 21.0 m / min

[0358] Examples I-2 to I-5, Comparative Examples I-1 to I-4 Resin compositions of Examples I-2 to I-5 and Comparative Examples I-1 to I-4 were prepared in the same manner as in Example I-1, except that the types and amounts of each component were changed as shown in Tables I-1 and I-2 below.

[0359] The resin compositions obtained in the Examples and Comparative Examples were subjected to the following thermal stability evaluation.

[0360] [Thermal Stability Evaluation] [YI Increase Rate] The pellet-shaped resin compositions of Examples I-1 to I-5 and Comparative Examples I-1 to I-4 were pulverized at 650 rpm in a pulverizer (SKR16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain pulverized material of 1 to 5 mm square. The obtained pulverized material was filled into a cylinder with an inner diameter of 32 mm and a height of 30 mm, and the pulverized material was completely worn out. The YI value before heating was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.). The pulverized material was also heat-treated in an oven under air at 100°C for 7 days, and the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating (YI increase rate) was calculated. The larger this value, the more yellow the resin composition was colored after heating, indicating poorer thermal stability. The results are shown in Table I-1 below.

[0361] [Reduction Temperature] Using 5 mg of the pellet-shaped resin composition obtained in Example I-1 and Comparative Example I-1, the 5% reduction temperature (°C) and 10% reduction temperature (°C) were measured using a thermogravimetric analyzer (Perkin Elmer, Pyris 1 TGA) under a nitrogen atmosphere when the temperature was increased at 10°C / min. The higher the 5% reduction temperature (°C) and 10% reduction temperature (°C), the slower the resin composition decomposed, indicating that the resin composition had excellent thermal stability. The results are shown in Table I-2 below.

[0362]

[0363]

[0364] The results in Tables I-1 and I-2 show that the resin compositions of Examples I-1 to I-5, which use a carbon-14-containing polypropylene resin (A1), have improved thermal stability compared to the resin compositions of Comparative Examples I-1 to I-4, which correspond to the respective examples and use a petroleum-derived polypropylene resin (A'1). The reason for this is presumably that the carbon-14-containing polypropylene resin has stronger bond energy due to the primary isotope effect, which slows the decomposition of the polypropylene resin itself and improves thermal stability. Molded articles, sheets, films, regrind layers, and multilayer structures containing a regrind layer, which contain the resin compositions of Examples I-1 to I-5, also have excellent thermal stability. Furthermore, multilayer structures having a regrind layer, a layer containing a polyolefin resin, an adhesive resin layer, and a layer containing an EVOH resin, and molded articles obtained by molding such multilayer structures, also have excellent thermal stability.

[0365] <<Second Aspect>> Prior to the Examples, the following components were prepared. [Polypropylene Resin (A)] Carbon-14-containing polypropylene resin (A1): Polypropylene resin containing carbon-14 (HP640J, manufactured by LyondellBasell), MFR (230°C, load 2160 g) 3.2 g / 10 min, biomass degree 40% or more, carbon-14 content 0.4 ppt or more Petroleum-derived polypropylene resin (A'1): Polypropylene resin (FY6, manufactured by Nippon Polypropylene Co., Ltd.), MFR (230°C, load 2160 g) 2.4 g / 10 min

[0366] [EVOH Resin (B)] Modified EVOH Resin (B1): Ethylene structural unit content 38 mol%, saponification degree 99.9 mol%, side chain 1,2-diol structural unit content 1.5 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min EVOH Resin (B'1): Ethylene structural unit content 29 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min, density 1.21 g / cm 3 , Saponification degree 99.9 mol%

[0367] [Acid-modified polyolefin resin (C)] Acid-modified polyolefin resin (C1): Maleic acid graft-modified polyolefin resin (manufactured by Mitsubishi Chemical Corporation, Modic (registered trademark) P674V), MFR (230°C, load 2160 g) 3.4 g / 10 min, density 0.890 g / cm 3

[0368] Example II-1 85.1% of a carbon-14-containing polypropylene resin (A1), 9.9% of a modified EVOH resin (B1), and 5% of an acid-modified polyolefin (C1) were dry-blended together, and then fed to a twin-screw kneader at a rate of 12 kg / hour using a mass feeder. The resulting mixture was then strand-cut using a drum pelletizer to prepare a pelletized resin composition. The kneading conditions were as follows: Twin-screw extruder: diameter 20 mm, L / D=48 (manufactured by Toshiba Machine Co., Ltd.) Extruder temperature settings: C1 / C2 / C3 / C4 / C5 / C6 / H=100 / 180 / 210 / 210 / 230 / 230 / 230 Screw rotation speed: 460 rpm Take-up speed: 21.0 m / min

[0369] Examples II-2 and II-3, Comparative Examples II-1 to II-3, and Reference Examples II-1 and II-2 The resin compositions of Examples II-2 and II-3, Comparative Examples II-1 to II-3, and Reference Examples II-1 and II-2 were prepared in the same manner as in Example II-1, except that the types and amounts of each component were changed as shown in Tables II-1 and II-2 below.

[0370] The resin compositions obtained in the Examples, Comparative Examples, and Reference Examples were subjected to the following thermal stability evaluation.

[0371] [Thermal Stability Evaluation] [Temperature Decrease Difference] Using 5 mg of the pellet-shaped resin compositions obtained in Examples II-1 to II-3 and Comparative Examples II-1 to II-3, the 5% temperature decrease (°C) and the 10% temperature decrease (°C) were measured using a thermogravimetric analyzer (Perkin Elmer, Pyris 1 TGA) under a nitrogen atmosphere while the temperature was increased at 10°C / min. The value (temperature decrease difference) was then calculated by subtracting the 5% temperature decrease from the 10% temperature decrease of the resin composition. The higher this value, the slower the decomposition of the resin composition, meaning that the resin composition has excellent thermal stability. The results are shown in Table II-1 below.

[0372] [YI Increase Rate] The pellet-shaped resin compositions of Example II-1, Comparative Example II-1, and Reference Examples II-1 and II-2 were pulverized at 650 rpm in a pulverizer (SKR16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain pulverized material of 1 to 5 mm square. The resulting pulverized material was packed into a cylinder with an inner diameter of 32 mm and a height of 30 mm, and the pulverized material was completely worn out. The YI value before heating was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.). The pulverized material was then heated in an oven under air at 100°C for 7 days, and the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating (YI increase rate) was calculated. The larger this value, the more yellow the resin composition became after heating, indicating poorer thermal stability. The results are shown in Table II-2 below.

[0373]

[0374]

[0375] The results in Tables II-1 and II-2 show that the resin compositions of Examples II-1 to II-3, which used a carbon-14-containing polypropylene resin (A1), had improved thermal stability compared to the resin compositions of Comparative Examples II-1 to II-3, which correspond to the respective Examples and used a petroleum-derived polypropylene resin (A'1). The reason for this is presumably that the carbon-14-containing polypropylene resin has stronger bond energy due to the primary isotope effect, which slows decomposition and enhances thermal stability. Furthermore, the results in Table II-2 show that the resin composition of Example II-1, which used a carbon-14-containing polypropylene resin (A1) and a modified EVOH resin (B1), had improved thermal stability compared to the resin composition of Comparative Example II-1, as in Table II-1. Furthermore, the resin composition of Example II-1, which used a carbon-14-containing polypropylene resin (A1) and a modified EVOH resin (B1), had significantly improved thermal stability compared to the resin compositions of Reference Examples II-1 and II-2, which used a carbon-14-containing polypropylene resin (A1) and an unmodified EVOH resin (B'1). It is presumed that the presence of a structural unit having a primary hydroxyl group in the side chain of the modified EVOH resin (B1) strengthens hydrogen bonds in the amorphous portion, stabilizing the molecular structure and thereby exhibiting significantly superior thermal stability. Molded articles, sheets, films, regrind layers, and multilayer structures containing a regrind layer, each containing the resin compositions of Examples II-1 to II-3, also exhibit excellent thermal stability. Furthermore, multilayer structures containing a regrind layer, a layer containing a polyolefin resin, an adhesive resin layer, and a layer containing an EVOH resin, as well as molded articles obtained by molding such multilayer structures, also exhibit excellent thermal stability.

[0376] <<Third Aspect>> Prior to the Examples, the following components were prepared. [Polypropylene Resin (A)] Carbon-14-containing polypropylene resin (A1): homopolypropylene resin containing carbon-14 (manufactured by LyondellBasell, HP640J), MFR (230°C, load 2160 g) 3.2 g / 10 min, biomass degree 40% or more, carbon-14 content 0.4 ppt or more Petroleum-derived polypropylene resin (A'1): polypropylene resin (manufactured by Japan Polypropylene, FY6), MFR (230°C, load 2160 g) 2.4 g / 10 min

[0377] [EVOH Resin (B)] EVOH Resin (B1-1): Ethylene structural unit content 29 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min, density 1.21 g / cm 3 EVOH resin (B2-1): ethylene structural unit content 44 mol%, MFR (230°C, load 2160 g) 3.5 g / 10 min, density 1.14 g / cm 3 , Saponification degree 99.9 mol%

[0378] [Acid-modified polyolefin resin (C)] Acid-modified polyolefin resin (C1): Maleic acid graft-modified polyolefin resin (manufactured by Mitsubishi Chemical Corporation, Modic (registered trademark) P674V), MFR (230°C, load 2160 g) 3.4 g / 10 min, density 0.890 g / cm 3

[0379] Example III-1 85.1% of a carbon-14 containing polypropylene resin (A1), 7.92% of an EVOH resin (B1-1), 1.98% of an EVOH resin (B2-1), and 5% of an acid-modified polyolefin resin (C1) were dry-blended together, and then fed to a twin-screw kneader at a rate of 12 kg / hour using a mass feeder. The resulting mixture was then strand-cut using a drum pelletizer to prepare a pelletized resin composition. The kneading conditions were as follows: [Kneading Conditions] Twin-screw extruder: diameter 20 mm, L / D=48 (manufactured by Toshiba Machine Co., Ltd.) Extruder temperature settings: C1 / C2 / C3 / C4 / C5 / C6 / H=100 / 180 / 210 / 210 / 230 / 230 / 230 Screw rotation speed: 460 rpm Take-up speed: 21.0 m / min

[0380] Example III-2, Comparative Examples III-1 and III-2, and Reference Examples III-1 to III-3 The resin compositions of Example III-2, Comparative Examples III-1 and III-2, and Reference Examples III-1 to III-3 were prepared in the same manner as in Example III-1, except that the types and amounts of each component were changed as shown in Table III-1 below.

[0381] The resin compositions of Examples III-1 and III-2, Comparative Examples III-1 and III-2, and Reference Examples III-1 to III-3 were subjected to the following thermal stability evaluations, and the results are shown in Table III-1 below.

[0382] [Thermal Stability Evaluation] [YI Increase Rate] The pellet-shaped resin compositions of Examples III-1 and III-2, Comparative Examples III-1 and III-2, and Reference Examples III-1 to III-3 were pulverized at 650 rpm in a pulverizer (SKR16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain pulverized material of 1 to 5 mm square. The obtained pulverized material was filled into a cylinder with an inner diameter of 32 mm and a height of 30 mm, and the pulverized material was completely worn out. The YI value before heating was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.). The pulverized material was also heat-treated in an oven under air at 100°C for 7 days, and the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating (YI increase rate) was calculated. The larger this value, the more yellow the resin composition was colored after heating, indicating poorer thermal stability.

[0383]

[0384] The results in Table III-1 show that the resin compositions of Examples III-1 and III-2, which used the carbon-14-containing polypropylene resin (A1), had improved thermal stability compared to the resin compositions of Comparative Examples III-1 and III-2, which correspond to the respective Examples and used the petroleum-derived polypropylene resin (A'1). The reason for this is presumably that the carbon-14-containing polypropylene resin has stronger bond energy due to the primary isotope effect, which slows decomposition and enhances thermal stability. Furthermore, the resin composition of Example III-1, which contains the carbon-14-containing polypropylene resin (A1) and two or more EVOH resins with different ethylene structural unit content ratios, also showed improved thermal stability compared to the resin composition of Reference Example III-1, which uses the carbon-14-containing polypropylene resin (A1) and only one EVOH resin. Similarly, the resin composition of Example III-2, which contains a carbon-14-containing polypropylene resin (A1) and two or more EVOH resins with different ethylene structural unit contents, exhibits improved thermal stability compared to the resin compositions of Reference Examples III-2 and III-3, which use a carbon-14-containing polypropylene resin (A1) and only one EVOH resin. This is presumably because the use of two or more EVOH resins with different ethylene structural unit contents allows radicals generated by thermal degradation to react preferentially with the EVOH resin with a higher ethylene structural unit content, thereby reducing radical reactions with the EVOH resin with a lower ethylene structural unit content. Therefore, the improved thermal stability of the EVOH resin with a lower ethylene structural unit content is presumably improved compared to an EVOH resin containing only a single ethylene structural unit. Furthermore, Comparative Examples III-1 and III-2 are resin compositions in which the petroleum-derived polypropylene resin (A'1) was used in place of Reference Examples III-2 and III-3. However, neither of these compositions exhibits particularly superior thermal stability compared to Reference Examples III-2 and III-3. Therefore, it can be seen that the resin composition containing the polypropylene resin (A1) containing 14 carbon atoms and two or more EVOH resins having different ethylene structural unit contents significantly improves the thermal stability.Molded articles, sheets, films, regrind layers, and multilayer structures containing the resin compositions of Examples III-1 and III-2 also have excellent thermal stability. Furthermore, multilayer structures having a regrind layer, a polyolefin resin layer, an adhesive resin layer, and an EVOH resin layer, and molded articles obtained by molding such multilayer structures also have excellent thermal stability.

[0385] <<Fourth Aspect>> Prior to the Examples, the following components were prepared. [Polypropylene Resin (A)] Carbon-14-containing polypropylene resin (A1): homopolypropylene resin containing carbon-14 (manufactured by LyondellBasell, HP640J), MFR (230°C, load 2160 g) 3.2 g / 10 min, biomass degree 40% or more, carbon-14 content 0.4 ppt or more Petroleum-derived polypropylene resin (A'1): polypropylene resin (manufactured by Japan Polypropylene, FY6), MFR (230°C, load 2160 g) 2.4 g / 10 min

[0386] [EVOH Resin (B)] EVOH Resin (B1): Ethylene structural unit content 29 mol%, MFR (230°C, load 2160 g) 3.8 g / 10 min, density 1.21 g / cm 3 , Saponification degree 99.9 mol%

[0387] [Acid-modified polyolefin resin (C)] Acid-modified polyolefin resin (C1): Maleic acid-modified polyolefin resin (manufactured by Mitsubishi Chemical Corporation, Modic (registered trademark) P674V), MFR (230°C, load 2160 g) 3.4 g / 10 min, density 0.890 g / cm 3

[0388] [Ethylene-α-olefin copolymer (F)] Unmodified ethylene-α-olefin copolymer (F1-1): Ethylene-α-olefin copolymer ("Tafmer A4085" manufactured by Mitsui Chemicals, Inc.), MFR (230 ° C, load 2160 g) 3.6 g / 10 min, density 0.885 g / cm 3 Acid-modified ethylene-α-olefin copolymer (F2-1): maleic anhydride-modified ethylene-butene copolymer ("MA8510" manufactured by Mitsui Chemicals, Inc.), MFR (230 ° C, load 2160 g) 2.4 g / 10 min, density 0.885 g / cm 3

[0389] Example IV-1 82.6% of a carbon-14 containing polypropylene resin (A1), 9.9% of an EVOH resin (B1), 2.5% of an ethylene-α-olefin copolymer (F1-1), and 5% of an acid-modified polyolefin (C1) were dry-blended together, and then fed to a twin-screw kneader at a rate of 12 kg / hour using a mass feeder. The resulting mixture was then strand-cut using a drum pelletizer to prepare a pelletized resin composition. The kneading conditions were as follows: [Kneading Conditions] Twin-screw extruder: diameter 20 mm, L / D=48 (manufactured by Toshiba Machine Co., Ltd.) Extruder temperature settings: C1 / C2 / C3 / C4 / C5 / C6 / H=100 / 180 / 210 / 210 / 230 / 230 / 230 Screw rotation speed: 460 rpm Take-up speed: 21.0 m / min

[0390] Examples IV-2 to IV-5, Comparative Examples IV-1 to IV-5, Reference Examples IV-1 to IV-3 The resin compositions of Examples IV-2 to IV-5, Comparative Examples IV-1 to IV-5, and Reference Examples IV-1 to IV-3 were prepared in the same manner as in Example IV-1, except that the types and amounts of each component were changed as shown in Table IV-1 below.

[0391] The resin compositions of the examples and comparative examples were subjected to the following thermal stability evaluations, and the results are shown in Tables IV-1 and IV-2 below.

[0392] [Thermal Stability Evaluation] [YI Increase Rate] The pellet-shaped resin compositions of Examples IV-1 to IV-5, Comparative Examples IV-1 to IV-5, and Reference Examples IV-1 to IV-3 were pulverized at 650 rpm in a pulverizer (SKR16-240, manufactured by Sometani Sangyo Co., Ltd.) to obtain pulverized material of 1 to 5 mm square. The obtained pulverized material was filled into a cylinder with an inner diameter of 32 mm and a height of 30 mm, and the pulverized material was completely worn out. The YI value before heating was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.). The pulverized material was also heat-treated in an oven under air at 100°C for 7 days, and the YI value after heating was measured in the same manner. The ratio of the YI value after heating to the YI value before heating (YI increase rate) was calculated. The larger this value, the more yellow the resin composition was colored after heating, indicating poorer thermal stability.

[0393] [Reduction Temperature] Using 5 mg of the resulting pellet-shaped resin compositions of Examples IV-1, IV-2, and IV-4, and Comparative Example IV-1, the 10% reduction temperature (°C) was measured in a nitrogen atmosphere using a thermogravimetric analyzer (Pyris 1 TGA, manufactured by Perkin Elmer) when the temperature was increased at 10°C / min. A higher 10% reduction temperature (°C) means that the resin composition decomposes more slowly, and therefore the resin composition has better thermal stability.

[0394]

[0395]

[0396] The results in Table IV-1 show that the resin composition of Example IV-2, which contains a carbon-14 polypropylene resin (A1) and an ethylene-α-olefin copolymer, exhibits a lower YI increase rate and significantly improved thermal stability compared to Comparative Example IV-1, which was modified only with petroleum-derived polypropylene resin (A'1). The reason for this is presumably that the carbon-14 polypropylene resin exhibits stronger bond energy due to the primary isotope effect compared to the petroleum-derived polypropylene resin not containing carbon-14, thereby slowing decomposition and improving thermal stability. The same presumption can be made for the results in Table IV-2. Furthermore, the results in Table IV-1 show that the resin compositions of Examples IV-1 to IV-5, which contain a carbon-14 polypropylene resin (A1) and an ethylene-α-olefin copolymer, exhibit improved thermal stability compared to the resin compositions of Reference Examples IV-1 to IV-3, which use a carbon-14 polypropylene resin (A1) but do not contain an ethylene-α-olefin copolymer. This is presumably because the inclusion of the ethylene-α-olefin copolymer allows EVOH to be uniformly dispersed in the carbon-14-containing polypropylene resin (A1), reducing localized thermal degradation of the EVOH, thereby improving thermal stability. Furthermore, in the systems using the petroleum-derived polypropylene resin (A'1) of Comparative Examples IV-1 to IV-5, the resin compositions of Comparative Examples IV-2 to IV-5 do not contain an ethylene-α-olefin copolymer, but have improved thermal stability compared to the resin composition containing an ethylene-α-olefin copolymer of Comparative Example IV-1. However, in the systems using the carbon-14-containing polypropylene resin (A1) of Examples IV-1 to IV-5 and Reference Examples IV-1 to IV-3, the resin compositions containing the ethylene-α-olefin copolymer of Examples IV-1 to IV-5 have improved thermal stability compared to the resin compositions not containing the ethylene-α-olefin copolymer of Reference Examples IV-1 to IV-3. In other words, it can be seen that an excellent effect of improving thermal stability is exhibited when the carbon-14-containing polypropylene resin (A1) and the ethylene-α-olefin copolymer are included. The molded articles, sheets, films, regrind layers, and multilayer structures containing regrind layers each containing the resin compositions of Examples IV-1 to IV-5 also have excellent thermal stability.Furthermore, a multilayer structure having a regrind layer, a layer containing a polyolefin resin, an adhesive resin layer, and a layer containing an EVOH resin, and a molded article obtained by molding such a multilayer structure also have excellent thermal stability.

[0397] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0398] The present resin composition can have higher thermal stability than resin compositions using petroleum-derived polypropylene resins. Therefore, molded articles made from the present resin composition and multilayer structures having a layer containing the present resin composition are useful as materials for various packaging containers.

Claims

1. A resin composition containing a carbon-14 containing polypropylene resin (A), an ethylene-vinyl alcohol copolymer (B), and an acid-modified polyolefin resin (C).

2. The resin composition according to claim 1, wherein the carbon-14 containing polypropylene resin (A) comprises a bio-polypropylene resin.

3. The resin composition according to claim 1 or 2, excluding the following resin composition [α]: Resin composition [α] comprising a polypropylene resin (A) containing 14 carbon atoms, an ethylene-vinyl alcohol copolymer (B), an acid-modified polyolefin resin (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one element selected from the d block of Period 4 of the Long Form Periodic Table.

4. The resin composition according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer (B) contains a structural unit having a primary hydroxyl group in the side chain.

5. The resin composition according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer (B) comprises an ethylene-vinyl alcohol copolymer (B1) and an ethylene-vinyl alcohol copolymer (B2) having different proportions of ethylene structural units, and the difference in the content of ethylene structural units between the ethylene-vinyl alcohol copolymer (B1) and the ethylene-vinyl alcohol copolymer (B2) is 4 mol % or more.

6. The resin composition according to claim 5, comprising at least an ethylene-vinyl alcohol copolymer (B1) having an ethylene structural unit content of 20 to 34 mol % and an ethylene-vinyl alcohol copolymer (B2) having an ethylene structural unit content of 35 to 60 mol %.

7. The resin composition according to claim 1 or 2, further comprising an ethylene-α-olefin copolymer (F).

8. The resin composition according to claim 7, wherein the content of the ethylene-α-olefin copolymer (F) is 0.01% by mass or more and 35% by mass or less based on the total mass of the resin composition.

9. A resin composition according to claim 1 or 2, wherein the polypropylene resin (A) containing 14 carbon atoms is a homopolypropylene.

10. A resin composition according to claim 1 or 2, wherein the carbon-14 containing polypropylene resin (A) contains a linear aliphatic hydrocarbon having 10 to 24 carbon atoms.

11. The resin composition according to claim 1 or 2, wherein the ethylene-vinyl alcohol copolymer (B) contains 20 to 60 mol % of ethylene structural units.

12. The resin composition according to claim 1 or 2, wherein the content of the ethylene-vinyl alcohol copolymer (B) is 0.01 to 15.0 mass % based on the total mass of the resin composition.

13. A resin composition according to claim 1 or 2, wherein the content of the polypropylene resin (A) containing carbon-14 is 10% by mass or more and 99% by mass or less relative to the total resin composition.

14. A resin composition according to claim 1 or 2, wherein the content of the acid-modified polyolefin resin (C) is 0.1 mass % or more and 20 mass % or less relative to the total resin composition.

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

16. A film comprising the resin composition according to claim 1 or 2.

17. A regrind layer comprising the resin composition of claim 1 or 2.

18. A multi-layer structure comprising a regrind layer according to claim 17.

19. The multilayer structure of claim 18, further comprising a layer comprising a polyolefin resin.

20. The multilayer structure of claim 18, further comprising an adhesive resin layer.

21. The multilayer structure of claim 18, further comprising a layer comprising an ethylene-vinyl alcohol copolymer different from the regrind layer.

22. A molded article obtained by molding the multilayer structure according to claim 18.

23. A method for producing a multilayer structure, comprising the step of co-extruding the resin composition according to claim 1 or 2.

24. A method for producing a molded article, comprising the step of molding the multilayer structure according to claim 18.

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