Method for producing petrochemical composition, chemical recycling method, method for producing recycled chemical starting material, method for producing polymer, method for producing molded body, petrochemical composition, recycled chemical starting material, polymer, and molded body

Abstract

The following is provided as a method for producing a petrochemical composition having a low content ratio of oxygen-containing compounds.　A method for producing a petrochemical composition, said method comprising a step for heating at 240-800°C and thermally decomposing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B), wherein ε-caprolactam is generated by the heating, and the content ratio of the ε-caprolactam to the entire petrochemical composition is 300 mass ppm or more.

Description

Method for producing an oil-based composition, chemical recycling method, method for producing recycled chemical raw materials, method for producing a polymer, method for producing a molded article, oil-based composition, recycled chemical raw materials, polymer, and molded article

[0001] The present invention relates to a method for producing an oil-based composition, a chemical recycling method, a method for producing recycled chemical raw materials, a method for producing a polymer, a method for producing a molded article, an oil-based composition, recycled chemical raw materials, a polymer, and a molded article. More specifically, the present invention relates to a method for producing an oil-based composition, a chemical recycling method, a method for producing recycled chemical raw materials, a method for producing a polymer, a method for producing a molded article, an oil-based composition, recycled chemical raw materials, a polymer, and a molded article in which the content of impurities such as oxygen-containing compounds contained in the oil-based composition is reduced.

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

[0003] In recent years, from the perspective of efficient resource utilization, there has been a growing demand for recycling used waste plastics, including EVOH resins. While thermal recycling, chemical recycling, and material recycling are known methods for recycling such waste plastics, thermal recycling accounts for the majority. However, since thermal recycling relies on recovering and utilizing the heat energy generated during incineration, there is a need for recycling methods that can reduce the environmental impact even further.

[0004] Unlike thermal recycling and material recycling, which reprocesses waste plastics into new products, chemical recycling is a method of returning high-molecular-weight plastics to a low-molecular-weight state (hydrocarbons) for reuse, and is expected to be a recycling method that can reduce the environmental impact even further. Furthermore, many polyolefins, which are commonly used in plastics, can now be recovered as naphtha raw materials (oil-based compositions) through chemical recycling.

[0005] For example, Patent Document 1 discloses a method for the chemical recycling of plastics, which involves thermally decomposing plastic waste containing olefin-based plastics and a specific amount of EVOH resin, catalytically decomposing the resulting thermal decomposition components, and recovering the decomposition oil or decomposition gas.

[0006] Japanese Patent Application Publication No. 5-345894

[0007] The present inventors have found that when an oil-based composition is produced by thermally decomposing plastic waste containing EVOH resin, as disclosed in Patent Document 1, not only the target hydrocarbons but also impurities such as oxygen-containing compounds, which are low-molecular-weight forms of high-molecular-weight plastics, are mixed in. These impurities, such as oxygen-containing compounds, can cause corrosion of equipment or inhibit decomposition when the oil-based composition is subjected to naphtha cracking (decomposition). Therefore, there is a need for an oil-based composition with a low content of impurities such as oxygen-containing compounds.

[0008] Therefore, the present invention provides a method for producing an oil-based composition with a low oxygen-containing compound content, a chemical recycling method, a method for producing recycled chemical raw materials, a method for producing polymers, a method for producing molded articles, an oil-based composition, recycled chemical raw materials, polymers, and molded articles.

[0009] However, in view of these circumstances, the present inventors have found that the above problem can be solved by generating ε-caprolactam by heating a resin composition containing EVOH resin and polyamide resin (B) at a specific high temperature, and by including a specific amount or more of ε-caprolactam in the oil-based composition.

[0010] In other words, the present invention has the following embodiments: [1] A method for producing an oily composition comprising the step of heating and thermally decomposing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B) at 240 to 800°C, wherein the heating generates ε-caprolactam, and the content ratio of the ε-caprolactam to the entire oily composition is 300 ppm by mass or more. [2] The method for producing an oily composition according to [1], wherein the polyamide resin (B) contains nylon-6 and / or nylon-6 / nylon 66 copolymer. [3] The method for producing an oily composition according to [1] or [2], wherein the temperature in the thermal decomposition step is 300 to 700°C. [4] The method for producing an oily composition according to any one of [1] to [3], wherein the content ratio of the polyamide resin (B) to the entire resin composition is greater than 0.1% by mass. [5] A method for producing an oily composition according to any one of [1] to [4], wherein the content ratio of the ε-caprolactam to the entire oily composition is 500 to 200,000 ppm by mass. [6] A method for producing an oily composition according to any one of [1] to [5], wherein the ε-caprolactam is derived from the polyamide resin (B). [7] A method for producing an oily composition according to any one of [1] to [6], further comprising a distillation step after the thermal decomposition step. [8] A method for producing an oily composition according to [7], wherein the conditions for the distillation step are a pressure of 100 to 760 mmHg and a temperature of 90 to 210°C. [9] A chemical recycling method using the method for producing an oily composition according to any one of [1] to [8].

[10] A method for producing recycled chemical raw materials, wherein naphtha containing the oily composition obtained by the method for producing an oily composition according to any one of [1] to [8] is subjected to naphtha cracking to obtain recycled chemical raw materials.

[11] The method for producing a recycled chemical raw material according to

[10] , wherein the recycled chemical raw material comprises ethylene and / or propylene.

[12] The method for producing a polymer, wherein a monomer composition containing the recycled chemical raw material obtained by the method for producing a recycled chemical raw material according to

[10] is polymerized to obtain a polymer.

[13] The method for producing a molded article, wherein a resin composition containing the polymer obtained by the method for producing a polymer according to

[12] is molded to obtain a molded article.

[14] An oil-based composition obtained by thermally decomposing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B), wherein the oil-based composition contains ε-caprolactam, and the content of ε-caprolactam is 300 ppm by mass or more with respect to the entire oil-based composition.

[15] The oil-based composition according to

[14] , wherein the ε-caprolactam is derived from the polyamide resin (B).

[16] A recycled chemical raw material obtained by naphtha containing the oil-based composition according to

[14] or

[15] undergoing naphtha cracking treatment.

[17] A polymer obtained by polymerizing the recycled chemical raw material according to

[16] .

[18] A molded article obtained by molding a resin composition containing the polymer according to

[17] .

[0011] In the present invention, the content of oxygen-containing compounds in the resulting oil-based composition can be reduced. The method for producing the oil-based composition, the chemical recycling method, the method for producing recycled chemical raw materials, the method for producing polymers, the method for producing molded articles, the oil-based composition, the recycled chemical raw materials, the polymers, and the molded articles using this method can also reduce the content of oxygen-containing compounds in the oil-based composition.

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

[0013] In this specification, "x and / or y (where x and y are any combination)" means at least one of x and y, and can mean x only, y only, or x and y. In this specification, when expressed as "X to Y" (where X and Y are any numbers), unless otherwise specified, it includes the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" or "preferably less than Y." In this specification, when expressed as "greater than or equal to X" (where X is any number) or "less than or equal to Y" (where Y is any number), it also includes the meaning of "preferably greater than X" or "preferably less than Y." In this specification, for numerical ranges described in stages, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Also, in numerical ranges described in this specification, the upper or lower limit of that numerical range can be replaced with the value shown in the example. In this specification, a preferred combination of embodiments is a more preferred embodiment. In this specification, all physical properties and characteristic values ​​are at 23°C unless otherwise specified. When describing measurement methods, etc., based on standards in this specification, unless otherwise specified, the standards shall be those in effect as of the filing date of this application (or the priority date, if applicable). If the standards have been abolished by that date, the standards in effect as of the date of abolition shall be used.

[0014] In this specification, unless otherwise specified, "main component" means a component that significantly affects 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. In this specification, "layer" means not only thick layers but also relatively thin layers such as "film," "tape," and "sheet."

[0015] A method for producing an oily composition according to one embodiment of the present invention (hereinafter sometimes referred to as "this production method") is a method for producing an oily composition comprising the step of heating and thermally decomposing a resin composition containing an EVOH resin (A) and a polyamide resin (B) at 240 to 800°C, wherein the heating generates ε-caprolactam, and the content ratio of the ε-caprolactam to the entire oily composition is 300 ppm by mass or more.

[0016] When a resin composition containing EVOH resin (A) and polyamide resin (B) is thermally decomposed, the polymer contained in the resin composition undergoes thermal decomposition and becomes low-molecular-weight due to heating, generating oxygen-containing compounds and the like. These oxygen-containing compounds tend to cause corrosion of equipment and inhibit decomposition when naphtha containing the oil-based composition is subjected to naphtha cracking treatment. Therefore, in this manufacturing method, it has been found that by heating the resin composition containing EVOH resin (A) and polyamide resin (B) at a specific high temperature to generate ε-caprolactam, and by including a specific amount or more of ε-caprolactam in the oil-based composition, the proportion of oxygen-containing compounds in the oil-based composition is reduced. Before explaining this manufacturing method, the resin composition used in this manufacturing method will be described below.

[0017] <Resin Composition> The resin composition is not particularly limited as long as it contains an EVOH resin (A) and a polyamide resin (B).

[0018] [EVOH resin (A)] The EVOH resin (A) used in the resin composition is a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and vinyl ester monomer, and is a water-insoluble thermoplastic resin.

[0019] 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 more preferably 4 to 7 carbon atoms are usually used. These are usually used individually, but multiple types may be used simultaneously as needed.

[0020] 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 a known method. The EVOH resin (A) produced in this way mainly consists of ethylene-derived structural units and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units that remain unsaponified.

[0021] The content of ethylene structural units in the EVOH resin (A) is preferably 20 to 60 mol%, more preferably 25 to 50 mol%, and even more preferably 25 to 35 mol%. The content of ethylene structural units can be controlled by the pressure of the ethylene when copolymerizing the vinyl ester monomer and ethylene. The content of ethylene structural units is usually, １ It is measured by 1H-NMR measurement. For example, １ 1H-NMR measurement was used, with DMSO-d as the measurement solvent. ６ A measurement method is used that employs a device and sets the measurement temperature to 50°C.

[0022] The degree of saponification in the EVOH resin (A) is preferably 90 to 100 mol%, more preferably 95 to 100 mol%, and even more preferably 99 to 100 mol%. The degree of saponification can be controlled by the amount of saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) used to saponify the ethylene-vinyl ester copolymer, the temperature, the time, etc. The degree of saponification of such EVOH resin (A) is usually, １ It is measured by 1H-NMR measurement. For example, １ 1H-NMR measurement was used, with DMSO-d as the measurement solvent. ６ A measurement method is used that employs a device and sets the measurement temperature to 50°C.

[0023] The melt flow rate (MFR) (2160 g load at 210°C) of the EVOH resin (A) is typically 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and more preferably 3 to 35 g / 10 min. The MFR is an indicator of the degree of polymerization of the EVOH resin (A) and can be adjusted by the amount of polymerization initiator and solvent used when copolymerizing ethylene and vinyl ester monomer.

[0024] Furthermore, the EVOH resin (A) may further contain structural units derived from the following comonomers, to the extent that they do not impede the effects of the present invention (for example, 10 mol% or less of the EVOH resin (A)).Examples of the comonomers include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 3-buten-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2-diol, and their esterified and acylated derivatives; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyl Hydroxyalkylvinylidene diacetates such as ruoxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydride) phthalic acid, (anhydride) maleic acid, (anhydride) itaconic acid, or their salts, or mono or dialkyl esters with 1 to 18 carbon atoms in the alkyl group; acrylamide, N-alkylacrylamide with 1 to 18 carbon atoms in the alkyl group, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its salts or its quaternary salts Acrylamides such as: methacrylamide, N-alkylmethacrylamide with 1 to 18 C1 of the alkyl group, N,N-dimethylmethacrylamide, 2-methacrylamidepropanesulfonic acid or its salts, methacrylamidopropyldimethylamine or its salts or its quaternary salts, etc.; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, etc.; vinyl cyanides such as acrylonitrile, methacrylnitrile, etc.; alkyl vinyl ethers with 1 to 18 C1 of the alkyl group, hydroxyl Examples include vinyl ethers such as cyalkyl vinyl ethers and alkoxyalkyl vinyl ethers; vinyl halogenated compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; allyl halogenated compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These can be used individually or in combination of two or more types.

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

[0026] Furthermore, the EVOH resin (A) may be a mixture of EVOH resins with different ethylene structural unit content, degree of saponification, degree of polymerization, copolymer components, etc.

[0027] The content of EVOH resin (A) in the resin composition is usually less than 100% by mass of the entire resin composition, preferably 99% by mass or less, and more preferably 98% by mass or less. The lower limit is usually 0.01% by mass. The range of the content is, for example, 0.01 to 99.99% by mass.

[0028] [Polyamide resin (B)] Examples of the polyamide resin (B) include polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhex Shamethylene sebamid (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / Examples include aliphatic polyamide resins such as 6,6), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon-12 / 6,6), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / nylon 66 copolymer, nylon 6 / nylon 10 copolymer), and ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / 6,6 / 6,10), as well as aromatic polyamide resins obtained by polycondensation reactions of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids or derivatives thereof such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid. These can be used individually or in combination of two or more.

[0029] Among the above, the polyamide resin (B) preferably contains a copolymer containing structural units derived from adipic acid, from the viewpoint of reducing the content of oxygen-containing compounds, and more preferably is a nylon 6 polyamide. In particular, it is even more preferable to contain nylon-6 and / or nylon-6 / nylon 66 copolymer, and especially preferable to contain nylon-6 and / or nylon-6 / nylon 66 copolymer as the main component of the polyamide resin (B).

[0030] Nylon 6 polyamides refer to polyamides that have structural units derived from ε-caprolactam as structural units of the polymer molecule. Such nylon 6 polyamides include not only homopolymers of ε-caprolactam, but also copolymers (copolymerized nylon 6) of ε-caprolactam with other lactams, or ε-caprolactam with other diamines and dicarboxylic acids, and preferably homopolymers of ε-caprolactam.

[0031] A typical homopolymer of ε-caprolactam is nylon-6. Nylon-6, a homopolymer of ε-caprolactam, is synthesized by ring-opening polymerization, anionic polymerization, etc.

[0032] Examples of copolymerized nylon 6 include copolymerized polyamides consisting of ε-caprolactam, hexamethylenediamine, and adipic acid (nylon-6 / nylon 66 copolymer: 6 / 66 nylon), condensed polymers of ε-caprolactam and ω-laurolactam (6 / 12 nylon), and copolymerized polyamides of ε-caprolactam, hexamethylenediamine, adipic acid, and ω-laurolactam (6 / 66 / 12 nylon).

[0033] There are no particular restrictions on the polymerization method of polyamides; any known method, such as thermal melt polycondensation, lactam ring-opening polymerization, or solution polymerization, can be used. Furthermore, monobasic acids such as acetic acid or benzoic acid, or monoacid bases such as hexylamine or aniline, can be added as molecular weight modifiers during polymerization. Additionally, if necessary, heat stabilizers and polymerization additives such as sodium phosphite, sodium hypophosphite, phosphorous acid, hypophosphorous acid, or hindered phenols can be added.

[0034] The ends of these nylon 6 polyamides may be sealed with a carboxylic acid or amine. When sealing, it is preferable to use a carboxylic acid or amine having 6 to 22 carbon atoms. Examples of carboxylic acids used for sealing include aliphatic monocarboxylic acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. These can be used individually or in combination of two or more.

[0035] Examples of amines used for sealing include aliphatic primary amines such as hexylamine, octylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, and behenylamine; aliphatic diamines such as hexamethylenediamine; and aromatic diamines such as metaxylenediamine. These can be used individually or in combination of two or more.

[0036] The relative viscosity of nylon 6 polyamide, as measured according to JIS K6810, is not particularly limited, but a relative viscosity of 2.0 to 6.5 is preferably used, measured at a concentration of 1% by mass in 98% by mass sulfuric acid at a temperature of 25°C. A relative viscosity above the lower limit tends to maintain the strength of the molded article, while a relative viscosity below the upper limit tends to maintain the injection welding strength. The relative viscosity of nylon 6 polyamide is more preferably 2.2 to 3.5. Multiple nylon 6 polyamides with different relative viscosities can be used.

[0037] For example, nylon 6 polyamide may sometimes contain ε-caprolactam as a residual monomer. ε-caprolactam reacts with moisture to initiate ring-opening polymerization, and due to the deterioration of moldability associated with this ring-opening polymerization, it is desired to reduce the content ratio of ε-caprolactam as much as possible when producing molded articles and the like using a resin composition.

[0038] In contrast, the resin composition used in the present embodiment contains polyamide resin (B) as an essential raw material. When the resin composition is thermally decomposed at a specific temperature, the generation of ε-caprolactam derived from polyamide resin (B) and the generation of oxygen-containing decomposed products by thermal decomposition of EVOH resin (A) occur in the same system. It is presumed that the reaction between ε-caprolactam and the oxygen-containing decomposed product produces water, which enables separation from the oil composition, and thus an oil composition with a low content of impurities such as oxygen-containing compounds can be obtained. As described above, ε-caprolactam functions not as an impurity that impairs the quality of the oil composition, but as an effective component contributing to the reduction of oxygen-containing compounds. Therefore, maintaining a specific amount without complete removal from the system is essential for obtaining a high-quality regenerated chemical raw material.

[0039] The content ratio of polyamide resin (B) is preferably more than 0.1% by mass of the entire resin composition, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and particularly preferably 2% by mass or more. Although the upper limit of the content ratio of polyamide resin (B) is not particularly limited, from the viewpoint of suppressing the generation of oxygen-containing compounds which are catalyst poisons for naphtha cracking, it is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, and particularly preferably 60% by mass or less. The range of the content ratio is, for example, more than 0.1% by mass and 90% by mass or less, etc.

[0040] Furthermore, the mass ratio of EVOH resin (A) to polyamide resin (B) contained in the resin composition [EVOH resin (A) / polyamide resin (B)] is usually 99 / 1 to 1 / 99, preferably 90 / 10 to 10 / 90, and more preferably 30 / 70 to 60 / 40. When the mass ratio of EVOH resin (A) to polyamide resin (B) is within the above range, the content of oxygen-containing compounds contained in the oil-based composition tends to be further reduced.

[0041] The resin composition may also contain thermoplastic resins other than EVOH resin (A) and polyamide resin (B), compounding agents, etc.

[0042] [Thermoplastic resins other than EVOH resin (A) and polyamide resin (B)] As the thermoplastic resin other than the EVOH resin (A) and polyamide resin (B), known thermoplastic resins can be used, for example, linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, polyethylene resins such as ethylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymers, polypropylene, propylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymers and other polypropylene resins, polybutene, polypentene, polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chains) and other (unmodified) polyolefin resins, and polyolefin resins in a broad sense including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with an unsaturated carboxylic acid or an ester thereof, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, chlorinated polyethylene, chlorinated polypropylene and other halogenated polyolefins, aromatic or aliphatic polyketones, etc. These may be used alone or in combination of two or more. Among these, polyolefin resins are preferred, and polyethylene resins are more preferred. It should be noted that each of linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, and high-density polyethylene is a term commonly used to represent a type of polyethylene.

[0043] When the resin composition contains a thermoplastic resin other than the EVOH resin (A) and the polyamide resin (B), the content ratio is usually 0.01 to 90% by mass relative to the entire resin composition, preferably 0.1 to 80% by mass, more preferably 1 to 70% by mass.

[0044] [Compounding Agents] Examples of compounding agents include those generally used in thermoplastic resins, such as inorganic double salts, plasticizers, oxygen absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants, lubricants, antibacterial agents, antiblocking agents, fillers, compatibilizers, etc. These can be used individually or in combination of two or more.

[0045] Examples of the inorganic double salt include hydrotalcite. Examples of the plasticizer include ethylene glycol, glycerin, aliphatic polyhydric alcohols such as hexanediol. Examples of the oxygen absorber include inorganic oxygen absorbers such as aluminum powder and potassium sulfite, ascorbic acid, fatty acid esters and metal salts of ascorbic acid, 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., a combination of polypropylene and cobalt), blends of carbon-carbon unsaturated bond-containing resins and transition metals (e.g., a combination of polybutadiene and cobalt), photo-oxidative decomposition resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinylanthraquinone), and polymeric oxygen absorbers such as those obtained by adding photoinitiators (such as benzophenone) or other antioxidants and deodorants (such as activated carbon) to these formulations.

[0046] If the resin composition contains a compounding agent, its content is usually 20% by mass or less of the total resin composition, preferably 15% by mass or less, and more preferably 10% by mass or less. The lower limit is 0% by mass, and the range of its content is, for example, 0 to 20% by mass.

[0047] [Shape of the resin composition] The shape of the resin composition is not particularly limited, but examples of preferred shapes include pellets, films, sheets, molded articles, and crushed materials, scraps, and irregularly shaped products obtained by crushing them.

[0048] The origin of the aforementioned pellets, films, sheets, molded articles, etc., is not particularly limited, but is preferably derived from post-consumer recycling (PCR) or post-industrial recycling (PIR).

[0049] If the shape of the resin composition is a molded article, the molded article may consist only of a layer containing EVOH resin (A) (hereinafter referred to as the "EVOH resin layer") or a layer containing polyamide resin (B) (hereinafter referred to as the "polyamide resin layer"), or it may be a molded article in which the EVOH resin layer and the polyamide resin layer are laminated. Furthermore, the molded article may consist of a multilayer laminate in which these EVOH resin layers, the polyamide resin layer, and a base resin layer mainly composed of a thermoplastic resin other than EVOH resin (A) and polyamide resin (B) (hereinafter, the resin used for the base material is referred to as the "base resin"). Examples of the base resin include thermoplastic resins other than the aforementioned EVOH resin (A) and polyamide resin (B).

[0050] Furthermore, the multilayer laminate may have multiple layers of EVOH resin, polyamide resin, and base resin, and adhesive resin layers containing adhesive resin may be interposed between these layers as needed.

[0051] The adhesive resin is appropriately selected depending on the base resin, and typically includes modified polyolefin polymers containing carboxyl groups obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like.

[0052] Examples of the modified polyolefin polymers containing the carboxyl group 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, and maleic anhydride graft-modified polyolefin resin. These can be used individually or in combination of two or more.

[0053] Furthermore, if the resin composition is in the form of a molded body, the molded body may be a molded body made of the single-layer film or a molded body made of the multi-layer film.

[0054] Next, the process for preparing the resin composition used in this manufacturing method will be described. The resin composition may be prepared to contain the EVOH resin (A) and the polyamide resin (B).

[0055] For example, when using a multilayer film in which an EVOH resin layer and a polyamide resin layer are laminated, this multilayer film can be used as is as the resin composition. If the content ratio of polyamide resin (B) in the resin composition is not within the range described above, a single-layer film or multilayer film can be mixed in to bring the content ratio of polyamide resin (B) within the range described above. Furthermore, if the single-layer film, multilayer film, or molded article used contains polyamide resin (B) but does not contain EVOH resin (A), or contains EVOH resin (A) but does not contain polyamide resin (B), EVOH resin (A) or polyamide resin (B) can be added separately and mixed in a known manner. In this way, the resin composition can be prepared.

[0056] The resin composition may be subjected to cutting or crushing before thermal decomposition. The methods for cutting and crushing are not particularly limited. For example, the cutting method may involve cutting with a cutting machine such as a slitter or shredder. For example, the crushing method may involve crushing with a crusher, or crushing in stages using multiple crushers, such as coarsely crushing with a primary crusher and then further crushing with a secondary crusher. These cutting and crushing processes may be used individually or in combination of two or more.

[0057] In this manufacturing method, the resin composition is first thermally decomposed to obtain an oil-based composition. However, if the resin composition contains a thermoplastic resin containing chlorine, such as polyvinyl chloride, it is preferable to perform a desalination treatment before thermal decomposition.

[0058] Examples of the desalination treatment methods include the known twin-screw extruder dechlorination method. The twin-screw extruder dechlorination method involves using a twin-screw extruder to melt the resin composition at 200 to 230°C, and then extruding it at approximately 350°C to separate hydrogen chloride. The desalination-treated resin composition is then subjected to thermal decomposition.

[0059] <This Manufacturing Method> This manufacturing method comprises a step of heating the resin composition at 240 to 800°C to thermally decompose it, thereby producing an oil-based composition. However, the oil-based composition may also be obtained through a purification step as described later. The temperature in the thermal decomposition step is preferably 250 to 600°C, and more preferably 300 to 500°C. When the heating temperature is within the above range, the content of oxygen-containing compounds in the oil-based composition tends to be reduced.

[0060] The heating time is usually 10 minutes or more, preferably 0.2 hours or more, and more preferably 0.3 hours or more. There is no particular upper limit, but it should be carried out until the resin composition is completely thermally decomposed, but it is usually 24 hours or less, preferably 12 hours or less, and more preferably 6 hours or less. The range of the heating time is, for example, 10 minutes to 24 hours.

[0061] The aforementioned heating causes thermal decomposition, generating ε-caprolactam in the oily composition. The manufacturing method will be described in detail below.

[0062] The apparatus used in the aforementioned pyrolysis process is not particularly limited, and examples include apparatus commonly used for the oil conversion of polyolefin resins, such as a pyrolysis tank for gasifying the resin composition and an apparatus equipped with a coagulation means for cooling the decomposition gas from the pyrolysis tank to produce oil.

[0063] Methods for thermally decomposing the resin composition include, for example, (i) decomposition by electric furnace, (ii) decomposition by iron acetate solution, and (iii) decomposition by fluid contact device. These can be used individually or in combination of two or more. These methods will be described below.

[0064] [(i) Method of decomposition using an electric furnace] The method of decomposition using an electric furnace involves filling an electric furnace (thermal decomposition chamber) equipped with a heater with the resin composition and heating it with the heater.

[0065] The heating temperature is 240 to 800°C, preferably 250 to 600°C, and more preferably 300 to 500°C. When the heating temperature is within the above range, there is a tendency to reduce the content of oxygen-containing compounds in the oil-based composition. Furthermore, when the temperature is above the lower limit, there is a tendency to shorten the decomposition time, and when the temperature is below the upper limit, there is a tendency to reduce the amount of wax in the resulting oil-based composition.

[0066] Furthermore, heating by the heater may be carried out in two or more temperature ranges from the viewpoint of decomposition efficiency. When heating in two or more temperature ranges, for example, it is preferable to heat at 240 to 450°C in the first stage to remove the resulting gas, and then raise the temperature to a higher temperature than the first stage, exceeding 400°C, to completely thermally decompose (second stage heating).

[0067] When decomposing the resin composition using the aforementioned electric furnace method, it is preferable to do so while injecting a carrier gas.

[0068] Examples of the carrier gas include noble gases such as helium, nitrogen, and carbon dioxide. Among these, helium and nitrogen are preferred, and helium is more preferred.

[0069] The flow rate of the carrier gas varies depending on the size of the pyrolysis vessel and is not particularly limited, but for example, if the capacity of the pyrolysis vessel is 500 mL, it is 0.05 to 0.5 L / min.

[0070] The aforementioned method of decomposition using an electric furnace may also involve catalytic decomposition using a catalyst.

[0071] Examples of the catalysts mentioned above include FCC catalysts and FCC waste catalysts. These can be used individually or in combination of two or more types.

[0072] The aforementioned FCC catalyst is a synthetic zeolite-based solid acid catalyst used in the fluid catalytic cracking (FCC) process of petroleum, and Al ２ O ３ The main component is [a certain substance], to which small amounts of Na, Fe, C, V, Ni, Sb, etc. are added. Furthermore, the FCC spent catalyst is a regenerated FCC catalyst. These FCC catalysts and FCC spent catalysts have an average specific gravity of 0.74 to 0.91, which is almost the same as the resin composition, and can therefore be thoroughly mixed with the resin composition in the pyrolysis tank.

[0073] The average particle size of the FCC catalyst and FCC waste catalyst is typically 40 to 80 μm. This average particle size can be measured using a laser diffraction particle size distribution analyzer or the like.

[0074] Furthermore, the amount of FCC catalyst and FCC waste catalyst used is usually 5 to 35 parts by mass, preferably 10 to 30 parts by mass, and more preferably 15 to 25 parts by mass, per 100 parts by mass of the resin composition.

[0075] In this way, the decomposed resin composition is gasified, generating decomposition gas. By recovering this decomposition gas, an oily composition can be obtained. The decomposition gas may also be recovered after being cooled to below its dew point and liquefied using known flocculation methods.

[0076] Furthermore, if the apparatus used in the decomposition method using an electric furnace is equipped with a cooler, it is also preferable to cool the obtained decomposition gas with the cooler. For example, it is also preferable to cool the gaseous oil composition obtained by the first heating, second heating, etc., with the cooler. The temperature of the cooler is usually 0 to 50°C, preferably 10 to 45°C, more preferably 20 to 40°C, and even more preferably 30 to 35°C. By cooling the gas obtained by the first heating, second heating, etc., with the cooler, gaseous components having a boiling point higher than the cooler temperature liquefy and return to the pyrolysis tank, thus tending to reduce the amount of impurities contained in the gas.

[0077] [(ii) Method of decomposition using iron acetate solution] As an example of a method of decomposition using iron acetate solution, the resin composition is brought into contact with the iron acetate solution heated at normal pressure and in the absence of air in a thermal decomposition tank to decompose the resin composition.

[0078] The wood acetic acid is the supernatant liquid produced when wood is dry-distilled, and the iron acetate solution is a liquid with a pH of 1.5 to 7 obtained by dissolving iron in wood vinegar. The wood vinegar contains wood-derived organic acids (such as acetic acid), alcohols, carbonyl compounds, and aromatic compounds (such as phenols and furans).

[0079] The temperature of the iron acetate solution is 240 to 800°C, preferably 300 to 500°C, more preferably 400 to 480°C, and even more preferably 410 to 430°C. When the heating temperature is within the above range, there is a tendency to reduce the content of oxygen-containing compounds in the oil-based composition. Furthermore, when the temperature is above the lower limit, there is a tendency to shorten the decomposition time, and when the temperature is below the upper limit, there is a tendency to reduce the amount of wax in the resulting oil-based composition.

[0080] The amount of the iron acetate solution is typically 10 to 40 parts by mass, preferably 15 to 35 parts by mass, and more preferably 20 to 25 parts by mass, per 100 parts by mass of the resin composition, from the viewpoint of thermal decomposition efficiency.

[0081] Furthermore, the amount of iron acetate solution is preferably 20 to 60% by volume relative to the internal volume of the pyrolysis tank. When the amount of iron acetate solution is above the lower limit, it is possible to ensure sufficient contact between the resin composition and the iron acetate solution, and the processing time tends to be shortened. When the amount is below the upper limit, it is not necessary to frequently discharge the iron acetate solution and decomposition residue, and the work tends to be simplified.

[0082] As mentioned above, the decomposition of the resin composition must be carried out in the absence of air. Therefore, it is preferable to carry out the decomposition of the resin composition while injecting a carrier gas.

[0083] Examples of the carrier gas include noble gases such as helium, nitrogen, and carbon dioxide. Among these, helium and nitrogen are preferred, and helium is more preferred.

[0084] The flow rate of the carrier gas varies depending on the size of the pyrolysis vessel and is not particularly limited, but for example, if the capacity of the pyrolysis vessel is 500 mL, it is 0.05 to 0.5 L / min.

[0085] In this way, the decomposed resin composition is gasified, generating decomposition gas. By recovering this decomposition gas, an oily composition can be obtained. Alternatively, the decomposition gas may be cooled to below its dew point using known flocculation methods to liquefy it before recovery.

[0086] Furthermore, the oily composition derived from the resin composition obtained by this method tends to be acidic because it contains components derived from iron acetate solution. Therefore, if the oily composition derived from the resin composition is acidic, it is preferable to neutralize it. Known methods can be used as the neutralization method.

[0087] [(iii) Decomposition method using a fluid contact apparatus] The fluid contact apparatus can be an apparatus commonly used in the field of petroleum refining, and basically comprises a reaction tower (reactor), a catalyst / product oil separator, a section for removing oil from the catalyst surface, and a catalyst regeneration tower as a single unit, with the catalyst circulating within this system.

[0088] The cracking method using a fluid catalytic contact apparatus is not particularly limited, and examples thereof include the UOP process from UOP, the Ultra Orthoflow process from M. W. Kellogg, and the R2R process from IFP.

[0089] As for the treatment conditions, the reactor temperature is 240 to 800°C, preferably 250 to 600°C, more preferably 300 to 500°C. When the temperature falls within the above range, the content of oxygen-containing compounds contained in the oil composition can be reduced.

[0090] As for other treatment conditions, the ranges generally used in fluid catalytic cracking of petroleum are applicable. For example, the reactor pressure is about 0.1 to 3.0 kg / cm ２ G, the mass ratio of the catalyst to the EVOH resin (A) (catalyst / EVOH resin) is about 4 to 8, the catalyst regeneration tower temperature is about 500 to 800°C, and the catalyst regeneration tower pressure is about 0.1 to 3.0 kg / cm ２ G.

[0091] Examples of the catalyst include the aforementioned FCC catalysts and spent FCC catalysts. These can be used alone or in combination of two or more thereof.

[0092] An oily composition can be obtained by these methods.

[0093] [Purification Step] It is preferable that the obtained oily composition is subjected to distillation to remove impurities such as water and tar. That is, the present production method preferably comprises a distillation step in the step of obtaining the oily composition.

[0094] As for the distillation conditions in the distillation step, for example, the pressure is preferably 100 to 760 mmHg. The temperature during distillation is preferably 70 to 250°C, more preferably 80 to 230°C, still more preferably 90 to 210°C. When the distillation conditions fall within the above range, an oily composition with few impurities tends to be obtained.

[0095] Furthermore, the obtained oily composition may be subjected to centrifugation or other methods to remove impurities such as water and tar. While ε-caprolactam, a water-soluble component, tends to be removed simultaneously when impurities such as water are removed during distillation or other purification processes, in this manufacturing method, it is preferable to control the amount of ε-caprolactam remaining in the oily composition by adjusting the distillation temperature, pressure, and time, or by selecting the cut-off point for fractional distillation.

[0096] <Oil-Converting Composition> An oil-converting composition (hereinafter sometimes referred to as "this oil-converting composition") which is one embodiment of the present invention is obtained in this way. This oil-converting composition may be a gas or a liquefied liquid. The content of ε-caprolactam in this oil-converting composition is 300 ppm by mass or more, preferably 500 to 200,000 ppm by mass, more preferably 1,000 to 100,000 ppm by mass, and even more preferably 2,000 to 50,000 ppm by mass. Within this range, the content of oxygen-containing compounds contained in the oil-converting composition can be reduced. The content of ε-caprolactam can be controlled by the content of polyamide resin (B) in the resin composition, heating of the resin composition at a specific temperature, etc. In the resin composition, polyamide resin (B) is contained as an essential raw material, and by thermally decomposing the resin composition at a specific temperature, ε-caprolactam derived from polyamide resin (B) is generated, and one of the features of the present invention is that the ε-caprolactam is ε-caprolactam derived from polyamide resin (B). One of the features of this invention is that the ε-caprolactam content in the oil-based composition is 300 ppm by mass or more. Since ε-caprolactam is a water-soluble compound, when it undergoes a general purification process (e.g., distillation, centrifugation, or water washing under specific conditions) to separate and remove the generated water and other impurities after the thermal decomposition process, most of it is usually removed from the oil-based composition. In contrast, in this manufacturing method, a specific range of ε-caprolactam is intentionally present in the oil-based composition by controlling the conditions of the purification process. This makes it possible to more effectively enjoy the aforementioned effect of reducing oxygen-containing compounds.

[0097] This oil-based composition contains polyamide resin (B) as a raw material, resulting in a low proportion of oxygen-containing compounds. This is because polyamide resin (B) is decomposed by thermal decomposition into amine derivatives such as cyclic oligomers, monomers, and gaseous molecules. When EVOH resin (A) is included in the resin composition, these amine derivatives react with aldehydes and ketones contained in the thermal decomposition products of EVOH resin (A) to produce imines and water. It is presumed that removing the resulting water reduces the concentration of oxygen-containing compounds in the oil-based composition.

[0098] Furthermore, the resulting oil-based composition may be subjected to a hydrogenation reaction using a hydrogenation catalyst used in the catalytic hydrogenation of petroleum. Hydrogenation tends to allow for adjustment of the oxygen-containing compound content in the oil-based composition.

[0099] The oxygen-containing compound content in the oil-based composition can be considered as the oxygen atom content, and the oxygen-containing compound content is preferably 80,000 ppm or less, and more preferably 70,000 ppm or less. The lower limit of the oxygen-containing compound content is not particularly limited; the lower the amount, the better, but it is usually 10 ppm or more. The range of this content is, for example, 10 to 80,000 ppm. Having the oxygen-containing compound content within this range is preferable from the viewpoint of preventing corrosion and decomposition inhibition of equipment during naphtha cracking.

[0100] The proportion of oxygen atoms and ε-caprolactam can be determined, for example, by measuring them using an elemental analyzer.

[0101] This liquefied composition can be used as a naphtha raw material. Furthermore, recycled chemical raw materials can be obtained by subjecting naphtha containing the liquefied composition to a conventionally known naphtha cracking treatment.

[0102] This oil-based composition has a low content of oxygen-containing compounds and is less likely to cause corrosion of equipment or inhibit decomposition during naphtha cracking, thus enabling the stable production of recycled chemical raw materials. Examples of recycled chemical raw materials obtained from naphtha containing the oil-based composition include ethylene, propylene, 1-butene, butadiene, isoprene, benzene, toluene, xylene, styrene, and other unsaturated hydrocarbons that are useful as petrochemical raw materials. Among these, ethylene and / or propylene are preferred because they can be used as raw materials for a wide range of products. That is, the recycled chemical raw materials may contain ethylene and / or propylene, or they may contain a mixture thereof, but it is preferable that they contain ethylene and / or propylene as the main component. In addition, other unsaturated hydrocarbons may be contained to the extent that they do not impair the effects of the present invention. The ethylene and / or propylene is more preferably ethylene or propylene, with ethylene being the most preferred.

[0103] The obtained recycled chemical raw material is preferably used as a monomer composition containing the recycled chemical raw material. The monomer composition contains the recycled chemical raw material as an essential raw material. The monomer composition may also contain other components as long as they do not impair the effects of the present invention. Examples of other components include monomers other than recycled chemical raw materials and compounding agents as described in the resin composition. Examples of monomers other than recycled chemical raw materials include monomers of petrochemical raw materials and monomers obtained by reacting recycled chemical raw materials. Examples of monomers obtained by reacting recycled chemical raw materials include ethylene vinyl acetate monomer.

[0104] Furthermore, the monomer composition may be polymerized to obtain a resin composition containing a polymer. Conventional polymerization methods may be used for polymerizing the monomer composition. Examples of the polymer include ethylene-vinyl acetate copolymers, and the obtained ethylene-vinyl acetate copolymer may be saponified to obtain an EVOH resin.

[0105] Furthermore, this resin composition may be molded to obtain a molded article. Conventional molding methods can be used to mold the resin composition.

[0106] Thus, the embodiments of the present invention make it possible to obtain an oil-based composition containing ε-caprolactam (C) in a specific proportion from a resin composition containing EVOH resin (A) and polyamide resin (B). Since the obtained oil-based composition has a low content of oxygen-containing compounds, it is possible to stably obtain recycled chemical raw materials, subsequent polymers, and molded articles, making it suitable as a chemical recycling method.

[0107] 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.

[0108] Prior to the examples, the following resins were prepared: • EVOH resin (A): SoarnoL® DC3203RB, manufactured by Mitsubishi Chemical Corporation: Ethylene structural unit content 32 mol%, MFR (210°C, load 2160 g) 3.8 g / 10 min, degree of saponification 99.9 mol% • Polyamide resin (B1): Novamid 1028EN (Nylon-6), manufactured by DSM Corporation • Polyamide resin (B2): Novamid 2430A-1 (Nylon-6 / 6,6), manufactured by DSM Corporation • ε-Caprolactam (C): ε-Caprolactam, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Density: 1.01 g / cm³ ３ , molecular weight 113g / mol

[0109] <Example 1> 97 parts of EVOH resin (A) pellets and 3 parts of polyamide resin (B1) were dry-blended and melt-kneaded at 230°C for 2 minutes using a plastograph (manufactured by Brabender) to obtain a resin composition. 0.5 mg of the obtained resin composition was placed in a Heartcut EGA-MS pyrosizer, and the decomposition gas generated when the temperature was raised using the following pyrosizer apparatus and conditions was cooled to -195°C and recovered as an oily composition. The oily composition was separated using the following GC / MS apparatus and conditions, and the proportion (ppm) of ε-caprolactam and oxygen-containing compounds in the oily composition was measured. The results are shown in Table 1.

[0110] [Pyrosizer equipment and conditions] ・Pyrolysis equipment: Frontier Labs multi-shot pyrosizer (EGA / PY-3030D) ・Pyrolysis conditions: 200°C (0 min) → heating at 10°C / min (30 min) → 500°C (0 min) Gas trap temperature: -195°C [GC / MS equipment and conditions] ・GC-MS analyzer: Agilent "GC7890A" / Agilent "MS5975C" ・Separation column: DB-Heavy WAX, length 60 m, inner diameter 0.25 mm, film thickness 0.50 μm ・Carrier gas: Helium ・Inlet temperature: 270°C ・Column temperature: 40°C (3 min) → 270°C (10 min), heating rate 10°C / min (23 min) ・Split ratio: 50:1 • Measurement mass range: 15 to 400

[0111] <Example 2> Except for changing EVOH resin (A) pellets to 95 parts and polyamide resin (B2) to 5 parts in Example 1, a resin composition and an oil-based composition were obtained in the same manner as in Example 1, and the proportions of ε-caprolactam and oxygen-containing compounds in the oil-based composition were measured. The results are shown in Table 1.

[0112] <Example 3> Except for changing EVOH resin (A) pellets to 50 parts and polyamide resin (B1) to 50 parts in Example 2, a resin composition and an oil-based composition were obtained in the same manner as in Example 1, and the proportions of ε-caprolactam and oxygen-containing compounds in the oil-based composition were measured. The results are shown in Table 1.

[0113] <Comparative Example 1> A resin composition and an oil-based composition were obtained in the same manner as in Example 1, except that a polyamide resin was not used. The results of measuring the proportions of ε-caprolactam and oxygen-containing compounds in the oil-based composition are shown in Table 1.

[0114] <Comparative Example 2> A resin composition and an oil-based composition were obtained in the same manner as in Example 1, except that 99.9 parts of EVOH resin (A) pellets and 0.1 parts of polyamide resin (B1) were changed. The results of measuring the proportions of ε-caprolactam and oxygen-containing compounds in the oil-based composition are shown in Table 1.

[0115] <Comparative Example 3> A resin composition and an oil-based composition were obtained in the same manner as in Example 1, except that 100 parts of EVOH resin (A) pellets (95.2% by mass of the total resin composition) and 5 parts of ε-caprolactam as compound (C) (4.8% by mass of the total resin composition) were added. The results of measuring the proportions of ε-caprolactam and oxygen-containing compounds in the oil-based composition are shown in Table 1.

[0116]

[0117] As shown in Table 1 above, the liquefied compositions obtained from the resin compositions containing EVOH resin (A) and polyamide resin (B) in Examples 1 to 3 had a lower content of oxygen-containing compounds, which are thought to cause corrosion and decomposition inhibition of equipment during naphtha cracking, compared to Comparative Examples 1 to 3. Thus, by using this liquefied composition in which the content of impurities such as oxygen-containing compounds has been sufficiently reduced, it is possible to minimize the influence of impurities in the recycled chemical raw materials, polymers, and molded articles obtained therefrom, and this will greatly contribute to suppressing corrosion and decomposition inhibition of equipment during naphtha cracking.

[0118] While the above embodiments illustrate specific forms of the present invention, these embodiments are merely illustrative and should not be interpreted restrictively. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0119] This manufacturing method and this oil-based composition have a low content of impurities such as oxygen-containing compounds, and are less likely to cause corrosion or inhibition of decomposition of equipment during naphtha cracking, making them suitable for chemical recycling.

Claims

1. A method for producing an oily composition comprising the step of heating and thermally decomposing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B) at 240 to 800°C, wherein the heating generates ε-caprolactam, and the content ratio of the ε-caprolactam to the entire oily composition is 300 ppm by mass or more.

2. The method for producing the oily composition according to claim 1, wherein the polyamide resin (B) comprises nylon-6 and / or nylon-6 / nylon-66 copolymer.

3. A method for producing an oily composition according to claim 1, wherein the temperature in the thermal decomposition step is 300 to 700°C.

4. The method for producing the oily composition according to claim 1, wherein the content ratio of the polyamide resin (B) to the entire resin composition is greater than 0.1% by mass.

5. The method for producing the oil-forming composition according to claim 1, wherein the content ratio of the ε-caprolactam to the entire oil-forming composition is 500 to 200,000 ppm by mass.

6. A method for producing the oily composition according to claim 1, wherein the ε-caprolactam is derived from the polyamide resin (B).

7. A method for producing an oily composition according to claim 1, comprising a distillation step after the thermal decomposition step.

8. The method for producing an oily composition according to claim 7, wherein the conditions for the distillation step are a pressure of 100 to 760 mmHg and a temperature of 90 to 210°C.

9. A chemical recycling method using a method for producing an oil-based composition according to any one of claims 1 to 8.

10. A method for producing recycled chemical raw materials, comprising naphtha containing an oil-based composition obtained by a method for producing an oil-based composition according to any one of claims 1 to 8, and then subjecting the naphtha to naphtha cracking to obtain recycled chemical raw materials.

11. The method for producing a recycled chemical raw material according to claim 10, wherein the recycled chemical raw material comprises ethylene and / or propylene.

12. A method for producing a polymer, comprising polymerizing a monomer composition containing a recycled chemical raw material obtained by the method for producing a recycled chemical raw material described in claim 10 to obtain a polymer.

13. A method for producing a molded article, comprising molding a resin composition containing a polymer obtained by the polymer production method described in claim 12 to obtain a molded article.

14. An oil-based composition obtained by thermal decomposition of a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B), wherein the oil-based composition contains ε-caprolactam, and the content of ε-caprolactam is 300 ppm by mass or more relative to the entire oil-based composition.

15. The oil-based composition according to claim 14, wherein the ε-caprolactam is derived from the polyamide resin (B).

16. A recycled chemical raw material obtained by naphtha cracking treatment of naphtha containing the oil-based composition according to claim 14 or 15.

17. A polymer obtained by polymerizing the recycled chemical raw material described in claim 16.

18. A molded article obtained by molding a resin composition containing the polymer described in claim 17.

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