Method for producing oil composition, chemical recycling method, method for producing recycled chemical raw material, method for producing polymer, and method for producing molded body

Abstract

Provided in the following is a method for producing an oil composition capable of reducing the content proportion of an oxygen-containing compound and a nitrogen-containing compound.　This method for producing an oil composition comprises a step for pyrolyzing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B) at 240-800°C. In the method, the content proportion of the polyamide resin (B) is 0.2-45 mass% with respect to the resin composition.

Description

Manufacturing method of oil-based composition, chemical recycling method, manufacturing method of recycled chemical raw materials, manufacturing method of polymer, manufacturing method of molded body

[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 polymers, and a method for producing molded articles, and more particularly 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 polymers, and a method for producing molded articles, which can reduce the content of oxygen-containing compounds and nitrogen-containing compounds contained in the oil-based composition.

[0002] Polyamide resins have transparency, gas barrier properties against oxygen and other gases, and mechanical strength, and are formed into films, sheets, bottles, and the like, and are widely used as various packaging materials, such as food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, and agricultural chemical packaging materials.

[0003] In recent years, there has been a demand for recycling used waste plastics in order to make effective use of resources. Thermal recycling, chemical recycling, and material recycling are known methods for recycling waste plastics, with thermal recycling accounting for the majority of these. However, because thermal recycling involves recovering and utilizing the thermal energy generated during incineration, there is a demand for recycling methods that can further reduce the environmental impact.

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

[0005] For example, Patent Document 1 discloses a method for chemically recycling plastics, in which plastic waste containing an olefin-based plastic and a specific amount of ethylene-vinyl alcohol copolymer (hereinafter referred to as "EVOH resin") is thermally decomposed, the resulting pyrolysis components are catalytically decomposed, and decomposition oil or decomposition gas is recovered.

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

[0007] The present inventors have discovered that when a method for thermally decomposing plastic waste containing EVOH resin, as disclosed in Patent Document 1, is used to thermally decompose plastic waste containing polyamide resin to produce an oil-derived composition, not only the desired hydrocarbons are obtained, but also high-molecular-weight plastics such as polyamide resin are decomposed into nitrogen-containing compounds and oxygen-containing compounds. These nitrogen-containing compounds and oxygen-containing compounds can cause corrosion of equipment and inhibit decomposition when naphtha containing the oil-derived composition is subjected to naphtha cracking treatment (cracking). Therefore, it is considered necessary to reduce the proportion of oxygen-containing compounds and nitrogen-containing compounds.

[0008] Therefore, an object of the present invention is to provide a method for producing an oil-based composition that can reduce the content ratio of oxygen-containing compounds and nitrogen-containing compounds, and a chemical recycling method, a method for producing recycled chemical raw materials, a method for producing polymers, and a method for producing molded articles that include the steps of the method for producing an oil-based composition.

[0009] In view of the above circumstances, the present inventors have discovered that the above problems can be solved by thermally decomposing a resin composition containing a specific ratio of polyamide resin and EVOH resin at a specific temperature.

[0010] That is, the present invention has the following aspects: [1] A method for producing an oil-based composition, comprising a step of thermally decomposing a resin composition containing an EVOH resin (A) and a polyamide resin (B) at 240°C to 800°C, wherein the content of the polyamide resin (B) is 0.2% by mass to 45% by mass based on the resin composition. [2] A method for producing an oil-based composition according to [1], wherein the polyamide resin (B) contains a copolymer containing a structural unit of the following formula (1): [3] The method for producing an oil-based composition according to [1] or [2], wherein the temperature in the thermal decomposition step is 300°C to 500°C. [4] The method for producing an oil-based composition according to any one of [1] to [3], wherein the ratio of oxygen atoms contained in the oil-based composition is 100,000 ppm or less based on the total oil-based composition. [5] The method for producing an oil-based composition according to any one of [1] to [4], wherein the ratio of nitrogen atoms contained in the oil-based composition is less than 20,000 ppm based on the total oil-based composition. [6] The method for producing an oil-based composition according to any one of [1] to [5], wherein a distillation step is included after the thermal decomposition step. [7] The method for producing an oil-based composition according to [6], wherein the distillation step is carried out under conditions of a pressure of 100 mmHg to 760 mmHg and a temperature of 90°C to 210°C. [8] A chemical recycling method using the method for producing an oil-based composition according to any one of [1] to [7]. [9] A method for producing a recycled chemical raw material, comprising subjecting naphtha containing an oil-derived composition obtained by the method for producing an oil-derived composition according to any one of [1] to [7] to naphtha cracking treatment to obtain a recycled chemical raw material.

[10] A method for producing a recycled chemical raw material according to [9], wherein the recycled chemical raw material is ethylene and / or propylene.

[11] A method for producing a polymer, comprising polymerizing a monomer composition containing the recycled chemical raw material obtained by the method for producing a recycled chemical raw material according to [9] or

[10] , to obtain a polymer.

[12] A method for producing a molded article, comprising molding a resin composition containing the polymer obtained by the method for producing a polymer according to

[11] , to obtain a molded article.

[0011] The oil composition obtained by the production method of the present invention can have reduced contents of oxygen-containing compounds and nitrogen-containing compounds.

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

[0013] In this specification, "X and / or Y (X and Y are any configuration)" means at least one of X and Y, and can mean three things: X only, Y only, or X and Y. In this specification, when "X to Y" (X and Y are any numbers) is expressed, unless otherwise specified, it means "X or more and Y or less," as well as "preferably more than X" or "preferably less than Y." In this specification, when "X or more" (X is any number) or "Y or less" (Y is any number) is expressed, it also means "preferably more than X" or "preferably less than Y." With regard to the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples. In this specification, the term "main component" means a component that has a significant effect on the properties of the target object, and the content of the component is usually 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

[0014] A method for producing an oil-based composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the present production method") comprises a step of thermally decomposing a resin composition containing EVOH resin (A) and polyamide resin (B) at 240°C to 800°C, wherein the content of the polyamide resin (B) is 0.2% by mass to 45% by mass relative to the resin composition. When a resin composition containing EVOH resin (A) and polyamide resin (B) is thermally decomposed, the polymers contained in the EVOH resin (A) and polyamide resin (B) are decomposed into smaller molecules, resulting in the production of oxygen- and nitrogen-containing compounds. These oxygen- and nitrogen-containing compounds tend to cause corrosion of equipment and inhibit decomposition during naphtha cracking treatment of naphtha containing the oil-based composition. Therefore, in the present production method, it has been discovered that the content of oxygen- and nitrogen-containing compounds in the oil-based composition can be reduced by thermally decomposing a resin composition containing specific proportions of polyamide resin (B) and EVOH resin (A) at a specific temperature. Before describing the present production method, the resin composition will be described.

[0015] [Resin Composition] The resin composition is not particularly limited as long as it contains an EVOH resin (A) and a polyamide resin (B).

[0016] [EVOH Resin (A)] The EVOH resin (A) is a resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer, and is a water-insoluble thermoplastic resin.

[0017] Vinyl acetate is typically used as the vinyl ester monomer because of its commercial availability and the efficiency of impurity removal during production. Examples of vinyl ester monomers other than vinyl acetate include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Typically, an aliphatic vinyl ester having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms, is used. These monomers are typically used alone, but multiple types may be used simultaneously as needed.

[0018] The copolymerization of ethylene with a vinyl ester monomer can be carried out using any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, but solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method. The EVOH resin produced in this manner is primarily composed of ethylene-derived structural units and vinyl alcohol structural units, with a small amount of vinyl ester structural units remaining unsaponified.

[0019] The content of the ethylene structural unit in the EVOH resin (A) is usually 20 mol% to 60 mol%, preferably 25 mol% to 50 mol%, particularly preferably 25 mol% to 35 mol%. The content of the ethylene structural unit can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene. The content of the ethylene structural unit can be controlled by the following: 1 It can be determined by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using d-DMSO as the measurement solvent and setting the measurement temperature at 50°C.

[0020] The saponification degree of the EVOH resin (A) is usually 90 mol% to 100 mol%, preferably 95 mol% to 100 mol%, and particularly preferably 99 mol% to 100 mol%. The saponification degree can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used when saponifying the ethylene-vinyl ester copolymer. The saponification degree of such an EVOH resin is 1 It can be determined by H-NMR measurement. For example, 1 The measurement method employs H-NMR measurement, using d-DMSO as the measurement solvent and setting the measurement temperature at 50°C.

[0021] The melt flow rate (MFR) (210°C, 2160 g load) of the EVOH resin (A) is usually 0.5 g / 10 min to 100 g / 10 min, preferably 1 g / 10 min to 50 g / 10 min, and particularly preferably 3 g / 10 min to 35 g / 10 min. The MFR is an index of the degree of polymerization of the EVOH resin (A), and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene with a vinyl ester monomer.

[0022] The EVOH resin (A) may further contain structural units derived from the following comonomers (for example, 10 mol % or less of the EVOH resin (A)) within the range that does not impair the effects of the present invention.Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-butene-1-ol, 3-butene-1,2-diol, 4-pentene-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation products; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyloxy-2-methylenepropane; hydroxyalkylvinylidene diacetates such as hydroxy-2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its acid salts or quaternary salts thereof acrylamides such as methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or an acid salt or a quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochloric acid vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These may be used alone or in combination of two or more.

[0023] Furthermore, as the EVOH resin (A), EVOH resins that have been "post-modified" by esterification, urethanization, acetalization, cyanoethylation, oxyalkylenation, or the like can also be used.

[0024] Furthermore, the EVOH resin (A) may be a mixture of EVOH resins having different ethylene structural unit contents, saponification degrees, polymerization degrees, copolymerization components, and the like.

[0025] The content of the EVOH resin (A) in the resin composition is usually 100% by mass or less, preferably 99% by mass or less, and particularly preferably 98% by mass or less, based on the total mass of the resin composition. The lower limit is usually 1% by mass. The range of the content is, for example, 1 to 100% by mass.

[0026] [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), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), and polyhexamethylene adipamide. Methylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), caprolactam / lauryllactam copolymer (nylon-6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6 Examples of suitable polyamide resins include aliphatic polyamide resins such as nylon-12 / 6.6, lauryllactam / 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). These may also be used alone or in combination of two or more. Among these, the polyamide resin (B) is preferably a copolymer containing a structural unit of the following formula (1), from the viewpoint of reducing the content of nitrogen-containing compounds, and more preferably nylon-6 and / or nylon-6 / nylon 66 copolymer:

[0027] The content of the polyamide resin (B) in the resin composition is 0.2 to 45% by mass, preferably 0.5 to 30% by mass, more preferably 1 to 25% by mass, and particularly preferably 1 to 20% by mass, based on the resin composition. When the content of the polyamide resin (B) is within the above range, the content of the nitrogen-containing compound in the oil-based composition can be reduced.

[0028] The mass ratio of the EVOH resin (A) to the 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 the EVOH resin (A) to the polyamide resin (B) is within the above range, the content of nitrogen-containing compounds contained in the oil-based composition tends to be further reduced.

[0029] The resin composition may contain a thermoplastic resin other than the EVOH resin (A) and the polyamide resin (B), a compounding agent, and the like.

[0030] [Thermoplastic Resin Other than EVOH Resin (A) and Polyamide Resin (B)] Examples of the thermoplastic resin other than the EVOH resin (A) and the polyamide resin (B) include known thermoplastic resins, such as polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; and (unmodified) polyolefins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain). Examples of suitable polyethylene resins include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with unsaturated carboxylic acids or their esters, 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, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, and aromatic or aliphatic polyketones. These may be used alone or in combination of two or more. Among these, polyolefin resins are preferred, and polyethylene resins are more preferred. The terms linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, and high-density polyethylene are commonly used terms to represent types of polyethylene.

[0031] When the resin composition contains a thermoplastic resin other than the EVOH resin (A) and the polyamide resin (B), the content thereof is usually 1 to 90% by mass, preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass of the resin composition.

[0032] [Additives] Examples of the additives include additives that are generally added to thermoplastic resins, such as inorganic double salts, plasticizers, oxygen absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (excluding those used as lubricants), antibacterial agents, antiblocking agents, fillers, compatibilizers, etc. These may be used alone or in combination of two or more.

[0033] Examples of the inorganic double salt include hydrotalcite. Examples of the plasticizer include aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and 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, gallic acid, polyhydric phenols such as hydroxyl group-containing phenolaldehyde 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), photooxidatively degradable resins (e.g., polyketones), anthraquinone polymers (e.g., polyvinyl anthraquinone), and polymeric oxygen absorbers such as those obtained by adding a photoinitiator (e.g., benzophenone), antioxidants other than those mentioned above, or deodorizers (e.g., activated carbon) to these blends.

[0034] When the resin composition contains a compounding agent, the content thereof is usually 20% by mass or less, preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on the total mass of the resin composition.

[0035] [Shape of Resin Composition] The shape of the resin composition is not particularly limited, and examples thereof include pellets, films, sheets, molded products, crushed products obtained by crushing these, broken materials, irregular products, and the like.

[0036] The origin of the pellets, films, sheets, molded bodies, etc. is not particularly limited, and may be, for example, those obtained from post-consumer recycling (PCR) or post-industrial recycling (PIR).

[0037] When the resin composition is in the form of a molded article, the molded article may be a single-layer molded article consisting of only 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 may be a multilayer molded article consisting of an EVOH resin layer and a polyamide resin layer laminated together. Furthermore, the molded article may be a multilayer molded article consisting of an EVOH resin layer or a polyamide resin layer laminated together with a base resin layer (hereinafter the resin used for the base resin) whose main component is a thermoplastic resin other than EVOH resin (A) and polyamide resin (B). Examples of the base resin include thermoplastic resins other than the aforementioned EVOH resin (A) and polyamide resin (B).

[0038] The multilayer laminate may have a plurality of EVOH resin layers, polyamide resin layers, and / or substrate resin layers, and further, an adhesive resin layer containing an adhesive resin may be interposed between these layers as needed.

[0039] The adhesive resin is appropriately selected depending on the base resin, and a representative example is a modified polyolefin polymer containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by addition reaction, graft reaction, or the like.

[0040] Examples of the modified polyolefin polymer containing a carboxy group include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymers, maleic anhydride graft-modified ethylene-ethyl acrylate copolymers, maleic anhydride graft-modified ethylene-vinyl acetate copolymers, maleic anhydride-modified polycyclic olefin resins, maleic anhydride graft-modified polyolefin resins, etc. These may be used alone or in combination of two or more.

[0041] Furthermore, when the resin composition is in the form of a molded article, the molded article may be a molded article made of the single-layer film or a molded article made of the multilayer film.

[0042] Next, the step of preparing the resin composition used in the present production method will be described. The resin composition may be prepared so as to contain the EVOH resin (A) and the polyamide resin (B).

[0043] For example, when a multilayer film having an EVOH resin layer and a polyamide resin layer laminated thereon is used, the multilayer film can be used as the resin composition as is. If the content of polyamide resin (B) in the resin composition does not fall within the above range, a single-layer film, a multilayer film, or the like can be mixed to bring the content of polyamide resin (B) within the above range. If the single-layer film, multilayer film, or molded article used contains a polyamide resin but not an EVOH resin, or if it contains an EVOH resin but not a polyamide resin, an EVOH resin or a polyamide resin can be added separately and mixed by a known method. In this way, the resin composition can be prepared.

[0044] The resin composition may be subjected to a cutting treatment or a pulverization treatment before being subjected to thermal decomposition. The method of the cutting treatment or the pulverization treatment is not particularly limited. Examples of the cutting treatment method include a method of cutting using a cutting machine such as a slitter or a shredder. Examples of the pulverization treatment method include a method of pulverization using a pulverizer, and a method of pulverization in stages using multiple pulverizers, such as coarse pulverization using a primary pulverizer and then further fine pulverization using a secondary pulverizer. These cutting treatments and pulverization treatments may be used alone or in combination of two or more.

[0045] In this manufacturing method, the resin composition is thermally decomposed to obtain a thermal decomposition product. However, if the recycled raw material contains a thermoplastic resin containing chlorine, such as polyvinyl chloride, it is preferable to perform a desalination treatment before the thermal decomposition.

[0046] Examples of the desalting method include a known twin-screw extruder dechlorination method. The twin-screw extruder dechlorination method is a method in which a resin composition is melted at 200°C to 230°C using a twin-screw extruder, and then extruded at about 350°C to separate hydrogen chloride. The desalted resin composition is then subjected to thermal decomposition.

[0047] <Present Production Method> The present production method comprises a step of thermally decomposing the resin composition at 240° C. to 800° C. The present production method will be described in detail below.

[0048] The apparatus used in this production method is not particularly limited and may be an apparatus typically used for converting polyolefin resins into oil, such as an apparatus equipped with a pyrolysis tank for gasifying a resin composition. The apparatus used in this production method may also be equipped with aggregating means for aggregating the decomposition gas from the pyrolysis tank to produce oil.

[0049] Examples of methods for thermally decomposing the resin composition include (i) a method of decomposing using an electric furnace, (ii) a method of decomposing using an iron pyroacetate solution, and (iii) a method of decomposing using a fluidized bed contactor. These methods may be used alone or in combination of two or more. Among these, method (i) is preferred. These methods are described below.

[0050] [(i) Decomposition Method Using an Electric Furnace] In the decomposition method using an electric furnace, the resin composition may be filled into an electric furnace (pyrolysis tank) equipped with a heater and heated with the heater. When decomposition is performed using an electric furnace, the apparatus may be equipped with a cooler for cooling the resulting decomposition gas.

[0051] The heating temperature is 240°C to 800°C, preferably 250°C to 600°C, and particularly preferably 300°C to 500°C. When the heating temperature is equal to or higher than the lower limit, the content of oxygen-containing compounds and nitrogen-containing compounds in the oil-forming composition can be reduced, while when the heating temperature is equal to or lower than the upper limit, the yield of hydrocarbons in the oil-forming composition can be increased. The "hydrocarbon" refers to a compound that does not contain heteroatoms and is composed only of carbon and hydrogen, such as ethylene or propylene.

[0052] The heating time is usually 10 minutes or more, preferably 0.2 hours or more, more preferably 0.3 hours or more. The upper limit is not particularly limited as long as the heating is continued until the resin composition is completely thermally decomposed, but is usually 24 hours or less, preferably 12 hours or less, more preferably 6 hours or less.

[0053] In addition, the heating by the heater may be performed in two or more temperature zones from the viewpoint of decomposition efficiency. When heating in two or more temperature zones, the conditions are, for example, preferably such that in the first heating stage, the material is heated at 240°C to 450°C, the resulting decomposition gas is removed, and then the material is heated to a temperature higher than that in the first heating stage, exceeding 400°C, to completely pyrolyze the material (second heating stage).

[0054] When the resin composition is decomposed by the method of decomposing using an electric furnace, it is preferable to carry out the decomposition while injecting a carrier gas.

[0055] Examples of the carrier gas include rare gases such as helium, nitrogen, carbon dioxide, etc. Among these, nitrogen is preferred.

[0056] The flow rate of the carrier gas varies depending on the size of the pyrolysis tank and is not particularly limited, but for example, when the capacity of the pyrolysis tank is 500 mL, the flow rate is 0.05 L / min to 0.5 L / min.

[0057] The method of cracking using an electric furnace is also preferably catalytic cracking using a catalyst.

[0058] Examples of the catalyst include FCC catalysts and FCC waste catalysts, which may be used alone or in combination of two or more.

[0059] The FCC catalyst is a synthetic zeolite-based solid acid catalyst used in the fluid catalytic cracking (FCC) process of petroleum, and is composed primarily of Al2O3, to which small amounts of Na, Fe, C, V, Ni, Sb, etc. are blended. The FCC waste catalyst is a regenerated FCC catalyst. These FCC catalysts and FCC waste catalysts have an average specific gravity of 0.74 to 0.91, which is almost the same as that of the resin composition, so they can be thoroughly mixed with the resin composition in the thermal cracking tank.

[0060] The average particle size of the FCC catalyst and FCC waste catalyst is usually 40 μm to 80 μm.

[0061] The amount of the FCC catalyst or FCC waste catalyst used is usually 5 to 35 parts by mass, preferably 10 to 30 parts by mass, and particularly preferably 15 to 25 parts by mass, per 100 parts by mass of the resin composition.

[0062] In addition, from the viewpoint of thermal decomposition efficiency, it is preferable to carry out the thermal decomposition of the resin composition while stirring.

[0063] The decomposed resin composition is gasified to generate a decomposition gas. The decomposition gas can be recovered to obtain a pyrolyzed product (oil composition). The decomposition gas may be liquefied by cooling it to a temperature below the dew point of the decomposition gas using a known coagulation method, and then recovered.

[0064] Furthermore, when the apparatus used in the method of decomposition using an electric furnace is equipped with a cooler, it is also preferable to cool the resulting cracked gas with the cooler. For example, it is also preferable to cool the cracked gas obtained by the first heating, second heating, etc. with the cooler. The temperature of the cooler is usually 0°C to 50°C, preferably 10°C to 45°C, more preferably 20°C to 40°C, and particularly preferably 30°C to 35°C. By cooling the gas obtained by the first heating, second heating, etc. with the cooler, gas components having a boiling point higher than the temperature of the cooler are liquefied and returned to the thermal decomposition tank, which tends to reduce the impurities contained in the cracked gas.

[0065] [(ii) Method of Decomposition Using Iron Pyroacetate Liquid] Examples of the method of decomposition using iron pyroacetate liquid include a method in which the resin composition is decomposed by bringing the iron pyroacetate liquid heated under normal pressure in the absence of air into contact with the resin composition in a pyrolysis tank.

[0066] The wood vinegar is the supernatant of the dry distillation liquid produced when wood is dry distilled, and the iron wood vinegar 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).

[0067] The temperature of the iron pyroacetate solution is usually 240° C. to 800° C., preferably 300° C. to 500° C., more preferably 400° C. to 480° C., and particularly preferably 410° C. to 430° C. When the heating temperature is within the above range, the content of nitrogen-containing compounds in the oil-forming composition can be reduced.

[0068] From the viewpoint of thermal decomposition efficiency, the amount of the iron pyroacetate solution is usually 10 to 40 parts by mass, preferably 15 to 35 parts by mass, and particularly preferably 20 to 25 parts by mass, per 100 parts by mass of the resin composition.

[0069] The amount of the ferric pyroacetate liquid is preferably 20 to 60% by volume relative to the internal volume of the pyrolysis tank. If the amount of ferric pyroacetate liquid is too small, the amount of resin composition that comes into contact with the ferric pyroacetate liquid will be small, which tends to lengthen the treatment time. If the amount is too large, the ferric pyroacetate liquid and decomposition residue will need to be frequently discharged, which tends to complicate the work.

[0070] As described above, the decomposition of the resin composition needs to be carried out in the absence of air, and therefore, it is preferable to carry out the decomposition of the resin composition while injecting a carrier gas.

[0071] Examples of the carrier gas include rare gases such as helium, nitrogen, and carbon dioxide.

[0072] The flow rate of the carrier gas varies depending on the size of the pyrolysis vessel and is not particularly limited, but for example, when the capacity of the reactor is 500 mL, the flow rate is 0.05 L / min to 0.5 L / min.

[0073] In addition, from the viewpoint of thermal decomposition efficiency, it is preferable to carry out the decomposition of the resin composition while stirring.

[0074] The decomposed resin composition is gasified to generate a decomposition gas. The decomposition gas can be recovered to obtain a pyrolysis product (oil composition). The decomposition gas may be liquefied by cooling it to a temperature below the dew point of the decomposition gas using a known coagulation method, and then recovered.

[0075] The pyrolyzate of the resin composition obtained by the method (ii) contains components derived from the iron pyroacetate solution and therefore tends to be acidic. Therefore, if the pyrolyzate of the resin composition is acidic, it is preferable to neutralize it. As the neutralization method, a known method can be used.

[0076] (iii) Cracking Method Using a Fluidized Contactor The fluidized contactor may be any device commonly used in the field of petroleum refining. Basically, the fluidized contactor comprises a reaction tower (reactor), a catalyst / product oil separator, a unit for removing oil from the catalyst surface, and a catalyst regeneration tower, and the catalyst circulates within the system in a fluidized state.

[0077] The decomposition method using a fluid contactor is not particularly limited, and examples thereof include the UOP type from UOP, the Ultra Ortho Flow type from M. W. Kellogg, and the R2R type from IFP.

[0078] As for the treatment conditions, the reactor temperature is 240° C. to 800° C., preferably 250° C. to 600° C., and particularly preferably 300° C. to 500° C. When the heating temperature is within the above range, the content of nitrogen-containing compounds contained in the oil-based composition can be reduced.

[0079] Other processing conditions are those generally used in fluid catalytic cracking of petroleum. For example, a reactor pressure of about 0.1 kg / cm 2 G~3.0kg / cm 2 G, catalyst to EVOH resin mass ratio (catalyst / EVOH resin) about 4 to 8, catalyst regeneration tower temperature about 500°C to 800°C, catalyst regeneration tower pressure about 0.1 kg / cm 2 G~3.0kg / cm 2 It's G.

[0080] The catalyst may be the above-mentioned FCC catalyst or FCC waste catalyst, which may be used alone or in combination of two or more.

[0081] The oil composition can be obtained by such various methods.

[0082] [Distillation Step] The obtained oil composition is preferably distilled to remove impurities such as water, tar, etc. That is, the present production method preferably includes a distillation step after the thermal decomposition step.

[0083] As for the distillation conditions in the distillation step, for example, the pressure is preferably 100 mmHg to 760 mmHg, and the temperature during distillation is preferably 70°C to 250°C, more preferably 80°C to 230°C, and particularly preferably 90°C to 210°C. When the distillation conditions are within the above ranges, an oil-based composition with few impurities tends to be obtained.

[0084] The obtained oil composition may be centrifuged to remove impurities such as water and tar.

[0085] The oil-based composition obtained in this manner contains a low content of oxygen-containing compounds because the raw resin composition contains polyamide resin (B). The reason for this is that polyamide resin (B) is decomposed by pyrolysis into amine derivatives such as cyclic oligomers, monomers, and gaseous molecules. When EVOH resin (A) is contained in the resin composition, these amine derivatives react with aldehydes and ketones contained in the pyrolyzed product of EVOH resin (A) to produce imines and water. It is presumed that removing the produced water results in a decrease in the concentration of oxygen-containing compounds in the oil-based composition.

[0086] The obtained oil composition may be subjected to a hydrogenation reaction using a hydrorefining catalyst used in catalytic hydrogen refining of petroleum. By performing the hydrogenation reaction, the content of oxygen-containing compounds in the oil composition tends to be able to be adjusted.

[0087] The content of the thermal decomposition product in the oil-forming composition is usually 10% by mass or more, preferably 30% by mass or more, and particularly preferably 50% by mass or more.

[0088] The content of oxygen-containing compounds contained in the oil-based composition can be considered as the content of oxygen atoms, and the content of oxygen atoms is preferably 100,000 ppm or less, more preferably 50,000 ppm or less. There is no particular lower limit for the content of oxygen atoms, and the lower the content, the better, but it is usually 10 ppm or more. When the content of oxygen atoms is within the above range, the content of nitrogen-containing compounds contained in the oil-based composition tends to be further reduced.

[0089] The content of nitrogen-containing compounds in the oil composition can be considered as the content of nitrogen atoms, and from the viewpoint of preventing corrosion of equipment and inhibition of decomposition during naphtha cracking treatment, the content of nitrogen atoms is preferably less than 20,000 ppm, more preferably 15,000 ppm or less, and particularly preferably 13,000 ppm or less, relative to the oil composition. There is no particular lower limit for the content of nitrogen atoms, and the lower the better, but it is usually 10 ppm or more.

[0090] The content ratio of the oxygen atoms and nitrogen atoms can be determined, for example, by measurement using an elemental analyzer.

[0091] The oil-reduced composition obtained by this production method can be used as a naphtha raw material. Furthermore, naphtha containing the oil-reduced composition can be subjected to a conventionally known naphtha cracking process to obtain a recycled chemical raw material.

[0092] The oil composition obtained by this production method has a high hydrocarbon content and is less likely to cause equipment corrosion or decomposition inhibition during naphtha cracking treatment, making it possible to stably obtain recycled chemical raw materials. Examples of recycled chemical raw materials obtainable from naphtha containing the oil composition include ethylene, propylene, 1-butene, butadiene, isoprene, benzene, toluene, xylene, styrene, and other unsaturated hydrocarbons that are useful as petrochemical raw materials. Of these, ethylene and / or propylene are preferred because they can be used as raw materials for a wide range of products, with ethylene or propylene being more preferred, and ethylene being the most preferred.

[0093] The obtained recycled chemical raw materials are preferably used as a monomer composition containing the recycled chemical raw materials. The monomer composition essentially contains the recycled chemical raw materials. The monomer composition may also contain other components as long as the effects of the present invention are not impaired. Examples of other components include monomers other than the recycled chemical raw materials and compounding agents described in the resin composition. Examples of monomers other than the 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 the recycled chemical raw materials include ethylene vinyl acetate monomer.

[0094] The monomer composition may be polymerized to form a resin composition containing a polymer. A conventionally known polymerization method may be used as the polymerization method for the monomer composition. Examples of the polymer include ethylene-vinyl acetate copolymer, and the resulting ethylene-vinyl acetate copolymer may be saponified to obtain an EVOH resin.

[0095] Furthermore, the resin composition may be molded to obtain a molded article. As a method for molding the resin composition, a conventionally known molding method may be used.

[0096] As described above, the embodiment of the present invention is suitable as a chemical recycling method because it is possible to obtain an oil-based composition from a resin composition containing an EVOH resin, and the obtained oil-based composition has a high hydrocarbon content, and therefore it is possible to stably obtain recycled chemical raw materials and subsequent polymers and molded articles.

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0098] Prior to the examples, the following resins were prepared. EVOH resin (A): SoarnoL DC3203RB manufactured by Mitsubishi Chemical Corporation: content of ethylene structural units: 32 mol%, MFR (210°C, load 2160 g): 3.8 g / 10 min, saponification degree: 99.9 mol% Polyamide resin (B1): Novamid 1020 (nylon-6) manufactured by DSM: MFR (230°C, load 2160 g): 10.0 g / 10 min Polyamide resin (B2): Novamid 2430A-1 (nylon-6 / 6,6) manufactured by DSM: MFR (230°C, load 2160 g): 2.3 g / 10 min Linear low-density polyethylene: NOVATEC manufactured by Japan Polypropylene Corporation UF240: MFR (190°C, load 2160g) 2.1g / 10 minutes, density 0.920g / cm 3 Acid-modified polyethylene: Plexar PX3236 manufactured by LyondellBasell: MFR (190°C, load 2160 g) 2.0 g / 10 min, density 0.922 g / cm 3

[0099] Example 1: A resin composition was prepared by dry blending the resins in a mass ratio of linear low-density polyethylene: acid-modified polyethylene: EVOH resin (A): polyamide resin (B1) = 70:10:10:10. 300 g of the resulting resin composition was placed in a 1 L round-bottom flask equipped with a condenser. While flowing nitrogen, the flask was heated using a mantle heater until the internal temperature reached 360°C to 400°C. The internal temperature was then maintained at 360°C to 400°C, and the resin composition was pyrolyzed over 3 to 4 hours. After confirming that the resin composition had completely decomposed into decomposition gas, the generated decomposition gas was liquefied and recovered using a condenser. The recovered liquid was naturally cooled to room temperature, yielding a pyrolysis oil mixture. The resulting mixture was distilled (at atmospheric pressure, heated to 150°C, and reduced pressure to 100 mmHg) to separate impurities such as water, yielding an oil-based composition.

[0100] Comparative Example 1: Each resin was dry-blended in a mass ratio of linear low-density polyethylene: acid-modified polyethylene: EVOH resin (A) = 80:10:10 to prepare a resin composition. 300 g of the obtained resin composition was placed in a 1 L round-bottom flask equipped with a condenser, and the temperature was raised to 360 ° C to 400 ° C using a mantle heater while flowing nitrogen. The resin composition was then pyrolyzed over 3 to 4 hours while maintaining the internal temperature at 360 ° C to 400 ° C. The generated decomposition gas was liquefied and recovered using a condenser, and the recovered liquid was allowed to cool to room temperature to obtain a pyrolysis oil mixture. The obtained pyrolysis oil mixture was distilled (heated to 150 ° C at atmospheric pressure and reduced pressure to 100 mmHg), and impurities such as water were separated to obtain an oil-based composition.

[0101] The nitrogen atom content of the obtained oil compositions of Example 1 and Comparative Example 1 was measured using an elemental analyzer (UNICUBE, manufactured by Emmental GmbH). The oxygen atom content was also measured using an elemental analyzer (Vario EL cube, manufactured by Emmental GmbH). The results are shown in Table 1 below.

[0102]

[0103] Example 2 An EVOH resin (A):polyamide resin (B1) was dry-blended at a mass ratio of 95:5, preheated at 230°C for 1 minute using a Plastograph (manufactured by Brabender), melt-kneaded for 2 minutes, and pelletized to produce a resin composition. An oil-based composition was obtained in the same manner as in Example 1, except that a resin composition dry-blended at a mass ratio of 95:5 was used.

[0104] Example 3 A resin composition was prepared in the same manner as in Example 2, except that the mass ratio of EVOH resin (A):polyamide resin (B1) was changed to 98:2. An oil-based composition was obtained in the same manner as in Example 2, except that a resin composition dry-blended at a mass ratio of EVOH resin (A):polyamide resin (B1) of 98:2 was used.

[0105] Example 4 A resin composition was prepared in the same manner as in Example 2, except that the mass ratio of EVOH resin (A):polyamide resin (B2) was changed to 95:5. An oil-based composition was obtained in the same manner as in Example 2, except that a resin composition dry-blended at a mass ratio of EVOH resin (A):polyamide resin (B2) of 95:5 was used.

[0106] Comparative Example 2 EVOH resin (A):polyamide resin (B1) were dry-blended at a mass ratio of 50:50, preheated at 230°C for 1 minute using a Plastograph (manufactured by Brabender), melt-kneaded for 2 minutes, and pelletized to produce a resin composition of Comparative Example 2. An oil-based composition was obtained in the same manner as in Comparative Example 1, except that a resin composition dry-blended at a mass ratio of 50:50 EVOH resin (A):polyamide resin (B1) was used.

[0107] <Comparative Example 3> A resin composition was prepared in the same manner as in Comparative Example 2, except that the mass ratio of EVOH (A) was changed to 100%. An oil-based composition was obtained in the same manner as in Comparative Example 1, except that a resin composition obtained by dry-blending EVOH resin (A):polyamide resin (B1) in a mass ratio of 99.9:0.1 was used.

[0108] The content of nitrogen atoms in the obtained oil compositions of Examples 2 to 4 and Comparative Examples 2 and 3 was measured using an elemental analyzer (UNICUBE, manufactured by Emmental GmbH). The content of oxygen atoms was also measured using an elemental analyzer (Vario EL cube, manufactured by Emmental GmbH). The results are shown in Table 2 below.

[0109]

[0110] The results in Table 1 above show that the oil composition of Example 1, obtained by thermally decomposing a resin composition containing EVOH resin (A) and a specific amount of polyamide resin (B) at a specific temperature, had a lower content of oxygen atoms derived from oxygen-containing compounds, which are thought to cause equipment corrosion and degradation inhibition during naphtha cracking treatment, compared to Comparative Example 1. Furthermore, the oil composition of Example 1 also had low contents of oxygen atoms derived from oxygen-containing compounds and nitrogen atoms derived from nitrogen-containing compounds. Furthermore, the results in Table 2 show that the oil compositions obtained by the production methods of Examples 2 to 4 also had low contents of oxygen atoms derived from oxygen-containing compounds and nitrogen atoms derived from nitrogen-containing compounds. On the other hand, the oil composition of Comparative Example 2 had a low content of oxygen atoms derived from oxygen-containing compounds but a high content of nitrogen atoms derived from nitrogen-containing compounds. Furthermore, the oil composition of Comparative Example 3 had a low content of nitrogen atoms derived from nitrogen-containing compounds but a high content of oxygen atoms derived from oxygen-containing compounds.

[0111] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0112] The present oil-refining composition has a low content of oxygen-containing compounds and nitrogen-containing compounds, and is unlikely to cause corrosion of equipment or inhibit decomposition during naphtha cracking treatment, making it suitable for use in chemical recycling.

Claims

1. A method for producing an oil-based composition, comprising a step of thermally decomposing a resin composition containing an ethylene-vinyl alcohol copolymer (A) and a polyamide resin (B) at 240°C to 800°C, wherein the content of the polyamide resin (B) is 0.2% by mass to 45% by mass of the resin composition.

2. The method for producing an oil-based composition according to claim 1, wherein the polyamide resin (B) comprises a copolymer containing a structural unit of the following formula (1):

3. The method for producing an oil-based composition according to claim 1 or 2, wherein the temperature in the thermal decomposition step is 300°C to 500°C.

4. The method for producing an oil composition according to claim 1 or 2, wherein the ratio of oxygen atoms contained in said oil composition is 100,000 ppm or less based on the total oil composition.

5. The method for producing an oil composition according to claim 1 or 2, wherein the ratio of nitrogen atoms contained in said oil composition is less than 20,000 ppm based on the total oil composition.

6. The method for producing the oil composition according to claim 1, further comprising a distillation step after the thermal decomposition step.

7. The method for producing an oil composition according to claim 6, wherein the distillation step is carried out under conditions of a pressure of 100 mmHg to 760 mmHg and a temperature of 90°C to 210°C.

8. A chemical recycling method using the method for producing an oil composition according to any one of claims 1 to 7.

9. A method for producing recycled chemical raw materials, which comprises subjecting naphtha containing an oil-derived composition obtained by the method for producing an oil-derived composition according to any one of claims 1 to 7 to naphtha cracking treatment to obtain recycled chemical raw materials.

10. The method for producing renewable chemical raw materials according to claim 9, wherein the renewable chemical raw materials are ethylene and / or propylene.

11. A method for producing a polymer, comprising polymerizing a monomer composition containing recycled chemical raw materials obtained by the method for producing recycled chemical raw materials according to claim 10 to obtain a polymer.

12. A method for producing a molded article, comprising molding a resin composition containing a polymer obtained by the method for producing a polymer according to claim 11 to obtain a molded article.

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