Resin compositions, pellets, reground layers, multilayer structures, molded articles, packaging materials, and food packaging materials

Abstract

The present invention provides a resin composition that can suppress discoloration caused by thermal degradation of the resin. [Solution] A resin composition comprising an ethylene-vinyl alcohol copolymer and a compound having the structure of the following formula (1), wherein the compound having the structure of formula (1) has 3 to 22 carbon atoms, and the content of the compound having the structure of formula (1) in the resin composition is 0.1 to 10,000 ppm by mass. TIFF2026142459000008.tif33170

Description

[Technical Field]

[0001] The present invention relates to resin compositions, pellets, reground layers, multilayer structures, molded articles, packaging articles, and food packaging materials. [Background technology]

[0002] Ethylene-vinyl alcohol copolymer (hereinafter referred to as "EVOH resin") has excellent transparency, gas barrier properties such as oxygen, fragrance retention, solvent resistance, oil resistance, and mechanical strength, and is molded into films, sheets, bottles, etc., and is widely used as a packaging material for various products such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials. Such sheet-like or film-like packaging materials can be manufactured using EVOH resin alone, but they are usually used as multilayer structures in which polyolefin resins or the like are laminated via an adhesive layer to impart water resistance, strength, and other functions.

[0003] Furthermore, after manufacturing molded products such as containers from the aforementioned multilayer structure, the recovered materials such as molded product scraps, unwanted parts such as edges, defective products, and various packaging materials may be melted and molded, and reused as a recycled layer (hereinafter sometimes referred to as the "regrind layer") in at least one layer of the multilayer structure.

[0004] For example, Patent Document 1 describes a multilayer structure that suppresses the migration of compounds with low SP values ​​from the recycled layer and has excellent flexibility, comprising at least a recycled resin layer mainly composed of recycled resin, a layer mainly composed of polyolefin resin, and two or more barrier layers mainly composed of EVOH resin, wherein the barrier layers are located on the outside and inside of the recycled resin layer, and the recycled resin layer further contains compounds having 30 or fewer carbon atoms and a lower SP value than EVOH resin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-28167 [Overview of the project] [Problems that the invention aims to solve]

[0006] EVOH resins are known to discolor due to thermal degradation, and when recycling EVOH resins, in particular, material recycling involves a significant thermal history during melting and heating, and chemical recycling involves a significant thermal history during thermal decomposition and depolymerization, making discoloration a problem. Therefore, it is considered necessary to have a resin composition that suppresses discoloration even when subjected to such thermal history. According to the inventors' research, while the multilayer structure disclosed in Patent Document 1 can suppress the migration of compounds with low SP values ​​from the recycled layer, its effect in suppressing discoloration was insufficient.

[0007] Therefore, against this background, the present invention aims to provide a resin composition that can suppress discoloration caused by thermal degradation of the resin. [Means for solving the problem]

[0008] However, in view of these circumstances, the inventors conducted extensive research and, as a result, discovered that a resin composition according to the first embodiment of the present invention contains EVOH resin and a compound having the structure of formula (1) described later, and by setting the content ratio of compound (X) in the resin composition (1) to 0.1 to 10,000 ppm by mass, a resin composition with suppressed discoloration is obtained, thus completing the present invention. Furthermore, the inventors discovered that a resin composition according to the second embodiment of the present invention contains EVOH resin and at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate, thus completing the present invention.

[0009] In other words, the present invention has the following aspects. [1] A resin composition comprising an EVOH resin and a compound having the structure of the following formula (1), The compound having the structure of formula (1) above has 3 to 22 carbon atoms, A resin composition in which the content of a compound having the structure of formula (1) is 0.1 to 10,000 ppm by mass. Resin composition. [ka] [2] R in equation (1) above 1 The resin composition according to [1], wherein is a methyl group or a butyl group. [3] The resin composition according to [1] or [2], wherein the compound having the structure of formula (1) is an ester of (meth)acrylic acid. [4] The resin composition according to [1], wherein the compound having the structure of formula (1) is at least one selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate. [5] A resin composition comprising an EVOH resin and at least one compound selected from the group consisting of tributyl acetyl citrate, methyl (meth)acrylate, and butyl (meth)acrylate. [6] The resin composition according to [5], wherein the total content of at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate in the resin composition is 0.1 to 10,000 ppm by mass. [7] A resin composition according to any one of [1] to [6], further comprising limonene. [8] The resin composition according to any one of [1] to [6], wherein the content of EVOH resin in the resin composition is 1 to 99% by mass. [9] The resin composition according to any one of [1] to [8] further comprising a polyolefin resin.

[10] The resin composition according to [9], wherein the polyolefin resin is a polyethylene resin.

[11] The resin composition according to [9], wherein the polyolefin resin is a polypropylene resin.

[12] The resin composition according to any one of [9] to

[11] , wherein a content ratio of the polyolefin resin in the resin composition is 1 to 99% by mass.

[13] A pellet comprising the resin composition according to any one of [1] to

[12] .

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

[12] .

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

[14] .

[16] The multilayer structure according to

[15] , further comprising an adhesive resin layer.

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

[15] .

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

[16] .

[19] A package comprising the multilayer structure according to

[15] .

[20] A package comprising the multilayer structure according to

[16] .

[21] A food packaging material comprising the multilayer structure according to

[15] .

[22] A food packaging material comprising the multilayer structure according to

[16] . Effects of the Invention

[0010] The resin composition of the present invention can suppress coloration derived from thermal degradation of the resin. Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described based on examples of modes for carrying out the present invention. However, the present invention is not limited to the embodiments described below.

[0012] In the present specification, "x and / or y (where x and y are arbitrary components)" means at least one of x and y, and includes three cases: only x, only y, and both x and y. In this specification, when "X~Y" (where X and Y are any numbers) is used, unless otherwise specified, it means "X or greater and Y or less," and also includes the meanings of "preferably greater than X" or "preferably less than Y." In this specification, when we use the expressions "X or more" (where X is any number) or "Y or less" (where Y is any number), we also mean "preferably greater than X" or "preferably less than Y." In this specification, the numerical ranges described in stages may be arbitrarily combined with the upper or lower limits of the numerical ranges in any stage. Furthermore, in the numerical ranges described herein, the upper or lower limits may be replaced with the values ​​shown in the examples.

[0013] In this specification, "main component" means a component that has a significant effect on the properties of the object, and the content of the component is usually 50% by mass or more of the object, preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and may be 100% by mass.

[0014] <Resin composition> The resin composition according to the first embodiment of the present invention (hereinafter referred to as "the resin composition (1)") is a resin composition comprising an EVOH resin and a compound having the structure of the following formula (1). Furthermore, the resin composition according to the second embodiment of the present invention (hereinafter referred to as "the resin composition (2)") is a resin composition comprising an EVOH resin and at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate. When both the resin composition (1) and the resin composition (2) are common, they are referred to as "the resin composition." The following explains each component. [ka]

[0015] [EVOH resin] The aforementioned EVOH resin is typically obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and vinyl ester monomers, and is a water-insoluble thermoplastic resin.

[0016] As the vinyl ester monomer, vinyl acetate is typically used due to its market availability and efficient impurity removal during manufacturing. Other vinyl ester monomers besides vinyl acetate include, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. However, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are usually used. These can be used individually or in combination of two or more.

[0017] The polymerization method for copolymerizing the ethylene and vinyl ester monomer can be any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, but generally, solution polymerization using methanol as the solvent is used. Furthermore, the saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by known methods.

[0018] The EVOH resin produced in this manner mainly consists of structural units derived from ethylene and vinyl alcohol, and contains a small amount of vinyl ester structural units that remain unsaponified.

[0019] The ethylene content in the EVOH resin is preferably 20 to 60 mol%, more preferably 25 to 55 mol%, and particularly preferably 25 to 50 mol%. The ethylene content can be controlled by the pressure of the ethylene when copolymerizing the vinyl ester monomer and ethylene, and when the ethylene content is within the above range, the resin tends to have excellent gas barrier properties and melt moldability. The content ratio of such ethylene structural units is usually,1 It is measured by 1H-NMR. For example, 1 A measurement method is used that employs 1H-NMR, with DMSO-d6 as the measurement solvent and a measurement temperature of 50°C.

[0020] The degree of saponification in the EVOH resin is typically 90-100 mol%, preferably 95-100 mol%, and particularly preferably 99-100 mol%. The degree of saponification can be controlled by the amount of saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used to saponify the ethylene-vinyl ester copolymer, the temperature, the time, etc. When the degree of saponification is within the above range, the resin tends to exhibit excellent gas barrier properties, thermal stability, and moisture resistance. The degree of saponification of such EVOH resin is usually, 1 It is measured by 1H-NMR. For example, 1 A measurement method is used that employs 1H-NMR, with DMSO-d6 as the measurement solvent and a measurement temperature of 50°C.

[0021] The melt flow rate (MFR) (2160g load at 210°C) of the EVOH resin is typically 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 3 to 35 g / 10 min. When the MFR is within this range, the film formation stability tends to be excellent. The aforementioned MFR is an indicator of the degree of polymerization of the EVOH resin and can be adjusted by the amount of polymerization initiator and solvent used when copolymerizing ethylene and vinyl ester monomers. The aforementioned MFR can be determined by using an automated melt flow rate tester (manufactured by Toyo Seiki Co., Ltd.) and measuring the rate at which the sample flows out 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.

[0022] Furthermore, the EVOH resin may also contain structural units derived from the following comonomers, within a range that does not impair the effects of the present invention (for example, 10 mol% or less of the EVOH resin). Examples of the aforementioned comonomers include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 3-buten-1,2-diol, 4-penten-1-ol, and 5-hexen-1,2-diol, and their esterified and acylated derivatives; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryl Hydroxyalkylvinylidene diacetates such as oxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydride) phthalic acid, (anhydride) maleic acid, (anhydride) itaconic acid, or their salts, or mono or dialkyl esters with alkyl groups having 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide with alkyl groups having 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or their salts, acrylamidopropyldimethylamine or its salts or its quaternary salts Acrylamides such as methacrylamide, N-alkylmethacrylamide with 1 to 18 carbon atoms in the alkyl group, N,N-dimethylmethacrylamide, 2-methacrylamidepropanesulfonic acid or its salts, methacrylamidopropyldimethylamine or its salts or its quaternary salts, etc.; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc.; vinyl cyanides such as acrylonitrile, methacrylnitrile, etc.; alkyl vinyl ethers with 1 to 18 carbon atoms in the alkyl group, etc. Examples include vinyl ethers such as droxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl halogenated compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halogenated compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamide-2-methylpropanesulfonic acid.These can be used individually or in combination of two or more types.

[0023] Among these, hydroxyl 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 hydroxyl group-containing α-olefins are copolymerized, the resulting EVOH resin has primary hydroxyl groups in its side chains. Such EVOH resins having primary hydroxyl groups in their side chains, and especially EVOH resins having 1,2-diol structures in their side chains, are preferred because they maintain gas barrier properties while exhibiting good secondary moldability.

[0024] When the EVOH resin has a primary hydroxyl group in its side chain, the content of structural units derived from the monomer having the primary hydroxyl group is typically 0.1 to 20 mol%, preferably 0.5 to 15 mol%, and particularly preferably 1 to 10 mol% of the EVOH resin.

[0025] Furthermore, as the EVOH resin, EVOH resins that have undergone "post-modification" such as esterification, urethaneization, acetalization, cyanoethylation, or oxyalkyleneization can also be used.

[0026] When using the post-modified EVOH resin described above, the modification rate is usually 10 mol% or less, preferably 4 mol% or less. When the modification rate of the EVOH resin is within the above range, it tends to have excellent thermal stability and excellent surface smoothness.

[0027] Furthermore, the EVOH resin may be a mixture of EVOH resins with different ethylene structural unit content, degree of saponification, degree of polymerization, copolymer components, etc.

[0028] The EVOH resin content in this resin composition is preferably 0.1 to 99% by mass, more preferably 1 to 99% by mass, more preferably 10 to 95% by mass, and even more preferably 30 to 90% by mass, relative to the total resin composition. When the content is within the above range, the effects of the present invention tend to be obtained more effectively.

[0029] [Compounds having the structure of formula (1)] The resin composition (1) contains a compound having the structure of formula (1) below, and the content of compound (X) in the resin composition (1) is 0.1 to 10,000 ppm by mass. The resin composition may contain one or more compounds having the structure of formula (1). The present resin composition (1) can suppress discoloration caused by thermal degradation of the resin by containing a compound having the structure of formula (1) below. The reason why the effects of the present invention can be obtained by using a compound having the structure of formula (1) below is presumed to be that the compound of formula (1) below undergoes thermal degradation by oxidation, etc., before the EVOH resin, thereby slowing down the degradation of the EVOH resin. [ka]

[0030] The number of carbon atoms in the compound having the structure of formula (1) is 3 to 22, preferably 5 to 20.

[0031] Also, R in formula (1) 1 The C1-C4 alkyl group is, for example, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, or a t-butyl group. Among these, a linear alkyl group having 1-C4 is preferred from the viewpoint of suppressing discoloration, more preferably a methyl group or an n-butyl group, and particularly preferably an n-butyl group.

[0032] The compound having the structure of formula (1) is preferably an ester of (meth)acrylic acid from the viewpoint of suppressing discoloration. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0033] Examples of compounds having the specific structure of formula (1) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, and tributyl acetylcitrate. Among these, from the viewpoint of suppressing discoloration, it is preferable that the compound be at least one selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate, with tributyl acetylcitrate being particularly preferred.

[0034] The content of the compound having the structure of formula (1) in this resin composition is 0.1 to 10,000 ppm by mass, preferably 0.1 to 7,000 ppm by mass, more preferably 0.1 to 5,000 ppm by mass, and particularly preferably 0.1 to 3,000 ppm by mass. By keeping the content of the compound having the structure of formula (1) below the upper limit, bleed-out can be suppressed, and by keeping it above the lower limit, an excellent effect of suppressing thermal degradation can be obtained. The content of the compound having the structure of formula (1) can be measured, for example, by gas chromatography-mass spectrometry. If multiple compounds having the structure of formula (1) are included, the total amount included should be between 0.1 and 10,000 ppm by mass. The conditions for the gas chromatography-mass spectrometry measurement are not particularly limited, but examples of analytical conditions include the following. (GC-MS analysis conditions) GC device: Agilent 7890 / Agilent 5977A Column: DB-5MSUI Column length: 30m, Column inner diameter: 250μm, Column film thickness: 0.25μm Introduction: Split 1:50 Injection volume: 1.0mL / min. GC oven temperature conditions: 40℃ (5 minutes) ~ 10℃ / minute ~ 300℃ (20 minutes) Gas flow rate: Helium 1 mL / min Ionization method: EI

[0035] [At least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate] From the viewpoint of suppressing discoloration, it is preferable that the resin composition (2) contains at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate (hereinafter sometimes referred to as "compound 2"). When this resin composition (2) contains compound 2, discoloration due to thermal degradation of the EVOH resin can be suppressed. The reason for this effect is presumed to be that at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate preferentially decomposes before the EVOH resin, thereby suppressing the thermal degradation of the EVOH resin and allowing it to be extruded from equipment such as extruders before it becomes discolored.

[0036] The total content of compound 2 in the resin composition (2) is preferably 0.1 ppm by mass or more and 10,000 ppm by mass or less, more preferably 0.1 ppm by mass or more and less than 7,000 ppm by mass, even more preferably 0.1 ppm by mass or more and 5,000 ppm by mass or less, and particularly preferably 1 ppm by mass or more and 3,000 ppm by mass or less. By keeping the total content of compound 2 below the upper limit, the bleed-out of compound 2 can be suppressed, and by keeping it above the lower limit, an excellent effect of suppressing thermal degradation can be obtained. The total content of compound 2 can be measured, for example, by gas chromatography-mass spectrometry. If multiple compounds are present, the total content of those multiple compounds 2 should be between 0.1 and 10,000 ppm by mass.

[0037] [Limonene] The resin composition is preferably further enriched with limonene from the viewpoint of suppressing discoloration. The aforementioned limonene has the chemical formula C 10 H 16 It is a monocyclic monoterpene represented by [formula]. When this resin composition contains limonene, discoloration due to thermal degradation of the EVOH resin can be further suppressed. The reason for this effect is presumed to be that the double bond contained in the molecular structure of limonene reacts with oxygen radicals and stabilizes, thereby further suppressing thermal degradation of the EVOH resin and thus suppressing discoloration.

[0038] The limonene is not particularly limited, and either D-limonene or L-limonene can be used.

[0039] The limonene content in this resin composition is 0.1 ppm by mass or more and 10,000 ppm by mass or less, preferably 0.1 ppm by mass or more and less than 5,000 ppm by mass, more preferably 0.1 ppm by mass or more and 3,000 ppm by mass or less, and particularly preferably 1 ppm by mass or more and 1,000 ppm by mass or less. By keeping the limonene content below the upper limit, limonene bleed-out can be suppressed, and by keeping it above the lower limit, an excellent effect of suppressing thermal degradation can be obtained. The limonene content can be measured, for example, by gas chromatography-mass spectrometry. The conditions for the gas chromatography-mass spectrometry measurement are not particularly limited, but examples of analytical conditions include the following. (GC-MS analysis conditions) GC device: Agilent 7890 / Agilent 5977A Column: DB-5MSUI Column length: 30m, Column inner diameter: 250μm, Column film thickness: 0.25μm Introduction: Split 1:50 Injection volume: 1.0mL / min. GC oven temperature conditions: 40℃ (5 minutes) ~ 10℃ / minute ~ 300℃ (20 minutes) Gas flow rate: Helium 1 mL / min Ionization method: EI

[0040] Furthermore, when limonene is used, the mass content ratio of the compound having the structure of formula (1) or compound 2 to limonene [compound having the structure of formula (1) or compound 2 / limonene] is usually 99 / 1 to 1 / 99, preferably 90 / 10 to 10 / 90, and more preferably 80 / 20 to 20 / 80, from the viewpoint of suppressing discoloration.

[0041] [Polyolefin resin] This resin composition preferably contains a polyolefin resin from the viewpoint of suppressing discoloration. As the polyolefin resin, any known polyolefin resin can be used, such as polyethylene resin, polypropylene resin, polybutene resin, polypentene resin, and polycyclic olefin resin (polymers having a cyclic olefin structure in the main chain and / or side chains). One or more of these can be used in combination. Among these, polyethylene resin and polypropylene resin are preferred from the viewpoint of suppressing discoloration.

[0042] [Polyethylene resin] The polyethylene resin is not particularly limited as long as it is a resin mainly composed of ethylene, and may be linear or branched. Examples of the polyethylene resin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and linear ultra-low-density polyethylene.

[0043] The polyethylene resin may be a homopolymer of ethylene, or it may be a copolymer mainly composed of ethylene and other copolymerizable monomer components. Furthermore, the polyethylene resin may be used alone, or two or more copolymerizable monomer components with different compositions and physical properties may be used in combination.

[0044] Further, examples of said other copolymerizable monomer components include α-olefins having 3 to 10 carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated carboxylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate, and ionomers thereof; and unsaturated compounds such as conjugated dienes and non-conjugated dienes.

[0045] The proportion of the other copolymerizable monomer component in said polyethylene resin is not particularly limited, but is usually 30% by mass or less, and more preferably 15% by mass or less.

[0046] The melting point of said polyethylene resin is usually 50 to 140°C, preferably 70 to 130°C. When the melting point of the polyethylene resin is within the above range, moldability tends to be excellent. Said melting point can be measured using a differential scanning calorimeter (DSC).

[0047] The melt flow rate (MFR) of said polyethylene resin is usually 0.1 to 20 g / 10 min, preferably 0.5 to 10 g / 10 min. When the MFR is within the above range, moldability tends to be excellent. Said MFR is measured in accordance with JIS K7210-1 (2014) under conditions of a temperature of 190°C and a load of 2160 g.

[0048] The density of said polyethylene resin is usually 0.860 to 0.980 g / cm 3 , preferably 0.870 to 0.960 g / cm 3 , more preferably 0.880 to 0.940 g / cm 3 . When the density is within the above range, moldability tends to be excellent. Said density is measured in accordance with JIS K7112 (1999).

[0049] [Polypropylene resin] The aforementioned polypropylene resin is not particularly limited as long as it is a resin mainly composed of propylene, and may be a homopolymer of propylene, or a copolymer mainly composed of propylene and other copolymerizable monomer components. Furthermore, the aforementioned polypropylene resin may be used alone, or two or more types with different copolymerizable monomer components, compositions, physical properties, etc., may be used in combination.

[0050] Examples of the aforementioned other copolymerizable monomer components include ethylene, α-olefins having 2 to 20 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene, as well as dienes such as divinylbenzene, 1,4-cyclohexadiene, dicyclopentadiene, cyclooctadiene, and ethylidene norbornene, vinyl acetate, (meth)acrylic acid, (meth)acrylic acid esters, glycidyl (meth)acrylate, vinyl alcohol, ethylene glycol, maleic anhydride, styrene, and cyclic olefins.

[0051] The polypropylene resin may be a polypolymer containing two or more of the above-mentioned copolymerizable monomer components. Furthermore, the polypropylene resin may be a block copolymer, a random copolymer, or a graft copolymer.

[0052] The melting point of the polypropylene resin is typically 70 to 170°C, preferably 80 to 160°C. When the melting point is within this range, the resin tends to have excellent moldability. The melting point can be measured using a differential scanning calorimetry (DSC).

[0053] The melt flow rate (MFR) of the polypropylene resin is not particularly limited, but is usually 0.2 g / 10 min or more, preferably 0.5 to 18 g / 10 min, and more preferably 1 to 15 g / 10 min. When the MFR is within this range, the moldability tends to be excellent. The aforementioned MFR is measured in accordance with JIS K7210-1 (2014) under conditions of a temperature of 230°C and a load of 2160g.

[0054] When the resin composition contains polyolefin resin, its content is preferably 1 to 99% by mass, more preferably 5 to 95% by mass, and particularly preferably 10 to 90% by mass. When the polyolefin resin content is within the above range, the discoloration of the resin composition tends to be further suppressed.

[0055] Furthermore, the mass content ratio of the EVOH resin to the polyolefin resin (EVOH resin / polyolefin resin) is typically 99 / 1 to 1 / 99, preferably 90 / 10 to 5 / 95, more preferably 70 / 30 to 10 / 90, and particularly preferably 50 / 50 to 10 / 90. When the mass content ratio is within the above range, the discoloration of the resin composition tends to be further suppressed.

[0056] [Other thermoplastic resins] This resin composition may contain thermoplastic resins other than EVOH resin and polypropylene resin in a range that does not impair the effects of the present invention (for example, usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, with a lower limit of usually 0% by mass).

[0057] Other thermoplastic resins can be known thermoplastic resins, such as polyester resins, polystyrene resins, polyvinyl chloride resins, polycarbonate resins, ionomers, polyvinylidene chloride, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, and chlorinated polypropylene. One or more of these may be used.

[0058] [Other compounding agents] Furthermore, the resin composition may contain compounding agents that are generally incorporated into EVOH resins, within a range that does not hinder the effects of the present invention (for example, 5% by mass or less of the resin composition, with the lower limit usually being 0% by mass).

[0059] Examples of the compounding agents include inorganic double salts (e.g., hydrotalcite), plasticizers (e.g., ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol, etc.), oxygen absorbers (e.g., inorganic oxygen absorbers such as aluminum powder and potassium sulfite; ascorbic acid, as well as its fatty acid esters and metal salts, etc.), polyhydric phenols such as gallic acid and hydroxyl group-containing phenol aldehyde resins, terpene compounds, blends of tertiary hydrogen-containing resins and transition metals (e.g., combinations of polypropylene resin and cobalt), and carbon-carbon unsaturated bond-containing resins. Blends with transition metals (e.g., polybutadiene resin and cobalt), photo-oxidative degradable resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), etc., as well as polymer oxygen absorbers such as those to which photoinitiators (e.g., benzophenone), antioxidants other than those mentioned above, or deodorants (e.g., activated carbon) have been added, as well as heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (except those used as lubricants), antibacterial agents, antiblocking agents, fillers (e.g., inorganic fillers), etc. These compounds can be used individually or in combination of two or more.

[0060] [Manufacturing of resin compositions] This resin composition can be produced, for example, by mixing the EVOH resin, a compound having the structure of formula (1), or compound 2, preferably limonene, a polyolefin resin, and optionally other thermoplastic resins and other compounding agents. Furthermore, the EVOH resin and polyolefin resin contained in this resin composition are not particularly limited, and virgin materials may be used. Alternatively, recycled materials such as scrap single-layer films and multilayer structures containing EVOH resin and polyolefin resin, unused packaging materials, and used packaging materials may be used.

[0061] First, we will explain the method for producing this resin composition using the recovered material. The aforementioned scrap and various packaging materials are typically crushed into pulverized products, and then, if necessary, their particle size is adjusted using a sieve or the like before being used as raw materials for this resin composition.

[0062] When the recovered material is used as a raw material for the resin composition, its content is typically 1 to 100% by mass of the resin composition, preferably 5 to 100% by mass, and more preferably 10 to 100% by mass.

[0063] The aforementioned recovered material can be crushed using a known crusher. If the pulverized product contains only EVOH resin as a resin component, the resin composition can be obtained by mixing this pulverized product with a compound having the structure of formula (1) or compound 2. In some cases, virgin EVOH resin may be used in addition to the pulverized product. Furthermore, if the resin composition contains polyolefin resin, virgin polyolefin resin may be added.

[0064] Furthermore, if the pulverized product contains EVOH resin and polyolefin resin as resin components, the resin composition can be obtained by mixing this pulverized product with a compound having the structure of formula (1) or compound 2. In some cases, virgin materials of EVOH resin or polyolefin resin may be used in addition to the pulverized product.

[0065] Furthermore, the contents of the packaging material may include a compound having the structure of formula (1) or compound 2 as a fragrance, and when a pulverized product is prepared from such packaging material, it may contain a compound having the structure of formula (1) or compound 2. In that case, virgin EVOH resin or polyolefin resin may be added to the pulverized product.

[0066] Examples of the aforementioned preparation methods include known methods such as the dry blending method, melt mixing method, solution mixing method, and impregnation method.

[0067] Examples of the dry blending method include (i) a method of dry blending (i) a pulverized product, and optionally virgin EVOH resin and polyolefin resin with a compound having the structure of formula (1) or compound 2 using a tumbler or the like.

[0068] Examples of the melt mixing method include (ii) a method of melting and kneading the dry blend described in (i), and (iii) a method of melting and kneading the molten pulverized product, and optionally virgin EVOH resin and polyolefin resin, with a compound having the structure of formula (1) or compound 2.

[0069] Examples of the solution mixing method include (iv) preparing a solution using the pulverized product, and optionally virgin EVOH resin and polyolefin resin, blending a compound having the structure of formula (1) or compound 2 therein, solidifying and molding, then separating the solid and liquid and drying.

[0070] Examples of the impregnation method include (v) a method in which the pulverized material, and optionally virgin EVOH resin and polyolefin resin, are brought into contact with an aqueous solution containing a compound having the structure of formula (1) or compound 2, and then dried.

[0071] In the present invention, it is possible to combine the above-mentioned different methods. In particular, The melt mixing method is preferred, and method (ii) is particularly preferred, as it yields a resin composition with greater productivity and more pronounced effects of the present invention. Furthermore, if the resin composition contains limonene, other thermoplastic resins, or other compounding agents, these may be added by known and generally accepted methods, such as dry blending, melt mixing, solution mixing, or impregnation.

[0072] As mentioned above, this resin composition is not limited to using recovered materials as raw materials, but may also be made using only virgin EVOH resin or polyolefin resin. In that case, the resin composition may be prepared using the dry blending method, melt mixing method, solution mixing method, impregnation method, or a combination thereof, so that each component is contained within a predetermined range.

[0073] The shape of the resin composition obtained by each of the above manufacturing methods is arbitrary, but it is preferably in the form of pellets.

[0074] The aforementioned pellets can be spherical, oval, cylindrical, die-shaped, or rectangular, but are usually oval or cylindrical. From the viewpoint of convenience when used later as a molding material, the size of the oval pellets is usually 1 to 10 mm in length, preferably 2 to 6 mm, and more preferably 2.5 to 5.5 mm in width, and the length is usually 1.5 to 30 mm, preferably 3 to 20 mm, and more preferably 3.5 to 10 mm in width. In the case of cylindrical pellets, the diameter of the base is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm. In the case of die-shaped pellets, one side is usually 1 to 6 mm, preferably 2 to 5 mm. Furthermore, it is preferable that the shape and size of the EVOH resin used in each of the above manufacturing methods are also the same.

[0075] The water content of this resin composition is not particularly limited, but is usually 0.01 to 0.5% by mass, preferably 0.05 to 0.35% by mass, and particularly preferably 0.1 to 0.3% by mass.

[0076] The moisture content is measured and calculated by the following method. The mass of the resin composition before drying (W1) is weighed using an electronic balance, dried in a hot air dryer at 150°C for 5 hours, and then weighed after cooling in a desiccator for 30 minutes (W2). The result is then calculated using the following formula. Moisture content (weight%)=[(W1-W2) / W1]×100

[0077] Furthermore, if the resin composition is in the form of pellets, it is preferable to attach a known lubricant to the surface of the pellets in order to stabilize the feedability during melt molding. Examples of the lubricants include higher fatty acids with 12 or more carbon atoms (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters (e.g., methyl esters, isopropyl esters, butyl esters, octyl esters of higher fatty acids, etc.), higher fatty acid amides (e.g., saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide; unsaturated higher fatty acid amides such as oleic acid amide, erucic acid amide; bis-higher fatty acid amides such as ethylenebis-stearic acid amide, ethylene-bis-oleic acid amide, ethylene-bis-erucic acid amide, ethylene-bis-lauric acid amide, etc.), low molecular weight polyolefin resins (e.g., low molecular weight polyethylene resins or low molecular weight polypropylene resins with a molecular weight of about 500 to 10000, or acid-modified products thereof), higher alcohols with 6 or more carbon atoms, ester oligomers, fluoroethylene resins, etc. These compounds can be used individually or in combination of two or more. Furthermore, the content of such lubricant is usually 5% by mass or less, preferably 1% by mass or less, of the resin composition. The lower limit is usually 0% by mass, for example, 0 to 5% by mass.

[0078] The resin composition obtained in this manner can suppress discoloration due to thermal degradation. The value of the color number "2730" (R:168, G:168, B:168, Brightness 168) relative to the color number "3276" (R:200, G:200, B:200, Brightness:200), measured using the visual analyzer IRIS VA400 (Alphamos), (

[2730] /

[3276] ) is usually 0.30 or less, preferably 0.25 or less, and more preferably 0.20 or less. The lower limit is usually 0, for example, usually 0 to 0.30. Brightness is the value obtained by adding the maximum and minimum values ​​of the RGB values ​​and dividing by 2. A smaller percentage indicates a higher proportion of color code "3276," suggesting a tendency for discoloration due to thermal degradation to be suppressed.

[0079] The value of the color number "2474" (R:152, G:168, B:168, Brightness:160) relative to the color number "3003" (R:184, G:184, B:184, Brightness:184), measured using the visual analyzer IRIS VA400 (Alphamos), (

[2474] /

[3003] ) is usually 0.12 or less, preferably 0.10 or less, and more preferably 0.09 or less. The lower limit is usually 0, for example, usually 0 to 0.12. Brightness is represented by the sum of the maximum and minimum values ​​of the RGB components, divided by two. A smaller percentage indicates a higher proportion of color code "3003," and a tendency for discoloration due to thermal degradation to be suppressed.

[0080] The value of the color number "2457" (R:152, G:152, B:152, Brightness:152) relative to the color number "2730" (R:168, G:168, B:168, Brightness:168), measured using the IRIS VA400 visual analyzer (Alphamos), (

[2457] /

[2730] ) is usually 0.5 or less, preferably 0.3 or less, and more preferably 0.25 or less. The lower limit is usually 0, for example, usually 0 to 0.5. Brightness is represented by the value obtained by adding the maximum and minimum values ​​of the RGB values ​​and dividing by 2. A smaller percentage indicates a higher proportion of color code "2730," suggesting a tendency for discoloration due to thermal degradation to be suppressed.

[0081] <Molding material> The resin composition obtained in this manner can be prepared in various forms, such as pellets, powder, or liquid, and provided as a molding material for various molded products. In particular, in this embodiment, it is preferable that the effects of the present invention be obtained more efficiently when the composition is provided as a material for melt molding.

[0082] Examples of the molded articles include single-layer films made from the resin composition, and multilayer structures having layers made from the resin composition. Furthermore, if the resin composition contains the recovered material, a single-layer film or a layer made from the resin composition can be suitably used as a regrind layer.

[0083] <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. The layer made of the resin composition in the multilayer structure (hereinafter simply referred to as "the resin composition layer") may be a single layer or a multilayer.

[0084] This multilayer structure can be further strengthened, protected from the effects of moisture, and given other functions by laminating it with a base layer mainly composed of a thermoplastic resin other than EVOH resin (hereinafter, the resin used in the base layer may be abbreviated as "base resin"), or with an EVOH resin layer mainly composed of EVOH resin, which is different from the layer made of this resin composition.

[0085] The base resin may be, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin with 4 to 20 carbon atoms) copolymers, (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chains), or these polyolefins may be modified with unsaturated carboxylic acids or other materials. Examples include polyolefin resins in a broad sense, such as modified olefin resins including unsaturated carboxylic acid-modified polyolefin resins grafted with esters, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These can be used individually or in combination of two or more. Linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene are all commonly used terms to describe different types of polyethylene.

[0086] Furthermore, the substrate layer may be subjected to surface treatment such as corona treatment.

[0087] The EVOH resin layer does not contain a compound having the structure of formula (1) or compound 2, and as the EVOH resin, the EVOH resin described in this resin composition can be used.

[0088] The layer configuration of this multilayer structure can also be R / a, a / R / a, R / a / R, R1 / R2 / a, R / a1 / a2, a2 / a1 / R / a1 / a2, a2 / a1 / R / a1 / a2, a2 / a1 / R / a1 / R / a1 / a2, b / R / a, a / R / b / a, a / R / b / R / a, a / b / R / b / a, a / R / b / R / a, a / R / b / R / b / a, etc., when the resin composition layer is R(R1, R2, ...), the base resin layer is a(a1, a2, ...), and the EVOH resin layer is b(b1, b2, ...). The total number of layers in this multilayer structure is typically 2 to 15, preferably 3 to 10. In the above layer configuration, adhesive resin layers containing adhesive resin may be interposed between each layer as needed.

[0089] As the adhesive resin, any known adhesive resin can be used, and it should be appropriately selected depending on the type of thermoplastic resin used in the base resin layer "a". Typical examples include modified polyolefin resins containing carboxyl groups, obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like. Examples of the above-mentioned modified polyolefin resins containing carboxyl groups include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, and the like. These may be used individually or in combination of two or more types.

[0090] In this multilayer structure, when an adhesive resin layer is used between the resin composition layer and the EVOH resin layer, it is preferable to use an adhesive resin with excellent hydrophobicity, since the adhesive resin layer is located on both sides of the EVOH resin layer.

[0091] The base resin layer, EVOH resin layer, and adhesive resin layer may contain conventionally known plasticizers, fillers, clays (such as montmorillonite), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, antiblocking agents, waxes, etc., within a range that does not impede the spirit of the present invention (for example, typically 30% by mass or less, preferably 10% by mass or less, with a lower limit of 0% by mass, for example, 0 to 30% by mass, per resin layer). These can be used individually or in combination of two or more.

[0092] The lamination of the resin composition layer, the substrate layer, and the EVOH resin layer (including cases where an adhesive resin layer is interposed) can be carried out by known methods. Examples of the lamination methods include: melt extrusion lamination of a base resin or EVOH resin onto the resin composition layer; melt extrusion lamination of the resin composition onto a base layer or EVOH resin layer; co-extrusion of the resin composition with a base resin or EVOH resin; dry lamination of the resin composition layer with a base layer or EVOH layer using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, or polyurethane compounds; and coating a solution of the resin composition onto a base layer or EVOH resin layer and then removing the solvent. Among these, considering cost and environmental factors, it is preferable to manufacture the product by including a step of melt molding a layer containing the resin composition layer, and specifically, the co-extrusion method is preferred.

[0093] This multilayer structure may be subjected to (heat) stretching treatment as needed. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, as for the stretching method, methods with a high stretch ratio such as roll stretching, tenter stretching, tubular stretching, stretch blowing, and vacuum pressure forming can be used. The stretching temperature is a temperature near the melting point of the multilayer structure, usually selected from a range of 40 to 170°C, preferably 60 to 160°C. When the stretching temperature is above the lower limit, the stretchability tends to be excellent, and when it is below the upper limit, it tends to be easier to maintain a stable stretched state.

[0094] Furthermore, the multilayer structure after stretching may be heat-set to impart dimensional stability. Heat-setting can be carried out by well-known means; for example, the stretched multilayer structure is heat-treated at a temperature of typically 80 to 180°C, preferably 100 to 165°C, for typically 2 to 600 seconds while maintaining tension.

[0095] When the stretched multilayer structure is used as a shrink film, in order to impart heat shrinkability, the above heat fixing process can be omitted, and instead, for example, the stretched multilayer structure can be cooled and fixed by applying cold air.

[0096] The thickness of this multilayer structure (including stretched versions), and furthermore, the thickness of the resin composition layer, base layer, EVOH resin layer, and adhesive resin layer constituting the multilayer structure, cannot be generalized as they depend on the layer configuration, the type of base resin, the type of adhesive resin, the application and packaging form, the required physical properties, etc. However, the thickness of this multilayer structure (including stretched versions) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and particularly preferably 50 to 2000 μm. The thickness of the resin composition layer is typically 5 to 3000 μm, preferably 10 to 2000 μm, and particularly preferably 20 to 1000 μm. The thickness of the base resin layer is typically 5 to 3000 μm, preferably 10 to 2000 μm, and particularly preferably 20 to 1000 μm. The thickness of the EVOH resin layer is 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm. The thickness of the adhesive resin layer is typically 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

[0097] In this multilayer structure, the ratio of the thickness of the resin composition layer to the substrate layer (resin composition layer / substrate layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60. In this multilayer structure, the thickness ratio of the resin composition layer to the EVOH resin layer (resin composition layer / EVOH resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 1 / 99 to 50 / 50, preferably 5 / 95 to 45 / 55, and particularly preferably 10 / 90 to 40 / 60. In this multilayer structure, the thickness ratio of the resin composition layer to the adhesive resin layer (resin composition layer / adhesive resin layer) is, if there are multiple layers, the ratio of the thickest layers, and is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10.

[0098] <Molded body> It is also possible to obtain cup- or tray-shaped molded products using this multilayer structure or single-layer films molded from this resin composition. In such cases, deep drawing is usually employed, specifically vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when obtaining tube- or bottle-shaped multilayer containers (laminated structures) from multilayer parisons (hollow tubular pre-molded products before blowing), blow molding is employed. Specifically, this includes extrusion blow molding (double-head type, mold-moving type, parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding, injection blow molding, and biaxial stretch blow molding (extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The resulting laminate can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or molten coating treatment, bag making, deep drawing, box making, tube making, splitting, etc., as needed.

[0099] <Package> Packaging materials such as bags, cups, trays, tubes, bottles, and lids, made from single-layer films or multi-layer structures molded from this resin composition, are useful as packaging materials for various products including general foods, condiments such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals (e.g., food packaging materials, pharmaceutical packaging materials, cosmetic packaging materials), and are particularly useful as food packaging materials. [Examples]

[0100] 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 unless it exceeds the gist of the invention. In the examples, "parts" and "%" refer to mass.

[0101] Prior to the examples, the following components were prepared.

[0102] [EVOH resin] • EVOH resin 1: Ethylene content 44 mol%, degree of saponification 99.6 mol%, MFR 3.0 g / 10 min (210°C, load 2160 g) • EVOH resin 2: Ethylene content 32 mol%, degree of saponification 99.6 mol%, MFR 12.0 g / 10 min (210°C, load 2160 g) [Additives] [Compounds having the structure of formula (1)] • Tributyl acetylcitrate: Manufactured by Tokyo Chemical Industry Co., Ltd. [Limonene] • Limonene: Manufactured by Tokyo Chemical Industry Co., Ltd. [Butanol] • Butanol: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. [Polyolefin resin] • Polyethylene resin (PE resin): Novatec UF641 manufactured by Nippon Polyethylene Co., Ltd., MFR 2.1g / 10min (190℃, load 2160g) • Polypropylene resin (PP resin): Novatec FY6 manufactured by Nippon Polypropylene Co., Ltd., MFR 2.5g / 10 min (230℃, load 2160g)

[0103] <Example 1> The resin composition of Example 1 was obtained by dry blending tributyl acetylcitrate into pellets of EVOH resin 1 at a concentration of 1 ppm by mass per resin composition, preheating at 190°C for 1 minute using a plastograph (manufactured by Brabender), and then melt-kneading for 2 minutes to form pellets.

[0104] <Examples 2-7, Comparative Examples 1-3> Except for changing the EVOH resin and additives used in Example 1 to those shown in Table 1 below, the resin compositions of Examples 2-7 and Comparative Examples 1-3 were obtained in the same manner as in Example 1.

[0105] [Coloring Evaluation 1] The resin compositions obtained in Examples 1-7 and Comparative Examples 1-3 were measured for the color intensity of color numbers "2730" and "3276" using a visual analyzer IRIS VA400 (Alphamos), and the degree of coloration was evaluated based on the value of "2730" / "3276". A smaller percentage indicates that discoloration due to thermal degradation is suppressed.

[0106] [Table 1]

[0107] <Example 8> A resin mixture was prepared by dry blending 10 parts of EVOH resin 1 pellets and 90 parts of polyethylene resin. Tributyl acetylcitrate was dry blended into this resin mixture to a concentration of 0.1 ppm by mass per resin composition. The mixture was preheated at 190°C for 1 minute using a plastograph (manufactured by Brabender), then melt-kneaded for 2 minutes to form pellets, thereby obtaining the resin composition of Example 8.

[0108] <Examples 9-13, Comparative Examples 4, 5> Except for changing the EVOH resin and additives used in Example 8 to those shown in Table 2 below, the resin compositions of Examples 9 to 13 and Comparative Examples 4 and 5 were obtained in the same manner as in Example 8.

[0109] [Coloring Evaluation 2] The resin compositions obtained in Examples 8-13 and Comparative Examples 4 and 5 were measured for the color intensity of color numbers "2474" and "3003" using a visual analyzer IRIS VA400 (Alphamos), and the degree of coloration was evaluated based on the value of "2474" / "3003". A smaller percentage indicates that discoloration due to thermal degradation is suppressed.

[0110] [Table 2]

[0111] <Example 14> A resin mixture was prepared by dry blending 10 parts of EVOH resin 1 pellets and 90 parts of polypropylene resin. Tributyl acetylcitrate was dry blended into this resin mixture to a concentration of 0.1 ppm by mass per resin composition. The mixture was preheated at 190°C for 1 minute using a plastograph (manufactured by Brabender), then melt-kneaded for 2 minutes to form pellets, thereby obtaining the resin composition of Example 14.

[0112] <Examples 15-19, Comparative Examples 6, 7> Except for changing the additives in Example 14 to those shown in Table 3 below, the resin compositions of Examples 15-19 and Comparative Examples 6 and 7 were obtained in the same manner as in Example 14.

[0113] [Coloring evaluation 3] The resin compositions obtained in Examples 14-19 and Comparative Examples 6 and 7 were measured for the color intensity of color numbers "2457" and "2730" using a visual analyzer IRIS VA400 (Alphamos), and the degree of coloration was evaluated based on the value of "2457" / "2730". A smaller percentage indicates that discoloration due to thermal degradation is suppressed.

[0114] [Table 3]

[0115] From the results in Tables 1 to 3 above, the resin compositions of the examples, which contain a compound having the structure of formula (1), with the compound having 3 to 22 carbon atoms, and in which the content ratio of the compound having the structure of formula (1) in the resin composition is 0.1 to 10,000 ppm by mass, showed lower coloration in the color evaluation compared to the resin compositions of the comparative examples, and coloration due to thermal degradation of the resin was suppressed. [Industrial applicability]

[0116] This resin composition is useful as a packaging material for various foods, as well as condiments such as mayonnaise and salad dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, and more, because it can suppress discoloration caused by thermal degradation of the resin.

Claims

1. A resin composition comprising an ethylene-vinyl alcohol copolymer and a compound having the structure of the following formula (1), The compound having the structure of formula (1) has 3 to 22 carbon atoms, A resin composition in which the content of a compound having the structure of formula (1) is 0.1 to 10,000 ppm by mass. Resin composition. 【Chemistry 1】

2. R in formula (1) １ The resin composition according to claim 1, wherein is a methyl group or a butyl group.

3. The resin composition according to claim 1, wherein the compound having the structure of formula (1) is an ester of (meth)acrylic acid.

4. The resin composition according to claim 1, wherein the compound having the structure of formula (1) is at least one selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate.

5. A resin composition comprising an ethylene-vinyl alcohol copolymer and at least one compound selected from the group consisting of tributyl acetyl citrate, methyl (meth)acrylate, and butyl (meth)acrylate.

6. The resin composition according to claim 5, wherein the total content of at least one compound selected from the group consisting of tributyl acetylcitrate, methyl (meth)acrylate, and butyl (meth)acrylate in the resin composition is 0.1 to 10,000 ppm by mass.

7. Furthermore, the resin composition according to claim 1 or 5, further comprising limonene.

8. The resin composition according to claim 1 or 5, wherein the content of ethylene-vinyl alcohol copolymer in the resin composition is 1 to 99% by mass.

9. Furthermore, the resin composition according to claim 1 or 5, further comprising a polyolefin resin.

10. The resin composition according to claim 9, wherein the polyolefin resin is a polyethylene resin.

11. The resin composition according to claim 9, wherein the polyolefin resin is a polypropylene resin.

12. The resin composition according to claim 9, wherein the content of polyolefin resin in the resin composition is 1 to 99% by mass.

13. A pellet comprising the resin composition according to claim 1 or 5.

14. A regrind layer comprising the resin composition according to claim 1 or 5.

15. A multilayer structure comprising the regrind layer described in claim 14.

16. Furthermore, the multilayer structure according to claim 15, further comprising an adhesive resin layer.

17. A molded body obtained by molding the multilayer structure described in claim 15.

18. A molded body obtained by molding the multilayer structure described in claim 16.

19. A packaging body comprising the multilayer structure described in claim 15.

20. A packaging body comprising the multilayer structure described in claim 16.

21. A food packaging material comprising the multilayer structure described in claim 15.

22. A food packaging material comprising the multilayer structure described in claim 16.

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