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

Abstract

Provided is a method for producing a petrochemical composition that has a high hydrocarbon content ratio and is capable of curtailing pyrolysis time.　The method for producing a petrochemical composition comprises: a first step for heating a resin composition containing an ethylene-vinyl alcohol copolymer (A) at a temperature of 240°C to 450°C and then maintaining the temperature within a range of the heating temperature ±30°C to remove the resulting gas; and a second step for heating the resin composition at a temperature exceeding 400°C, which is higher than the heating temperature of the first step.

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 a petrochemical raw material, a method for producing a polymer, and a method for producing a molded article, and more specifically to a method for producing an oil-based composition, a chemical recycling method, a method for producing a recycled chemical raw material, a method for producing a polymer, and a method for producing a molded article, which can increase the proportion of hydrocarbons contained in the oil-based composition and shorten the thermal decomposition time.

[0002] Ethylene-vinyl alcohol copolymers (hereinafter, sometimes referred to as "EVOH resins") are excellent in transparency, gas barrier properties such as oxygen and other gases, aroma retention, solvent resistance, oil resistance, mechanical strength, and the like, 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, in order to effectively utilize resources, there has been a demand for recycling used waste plastics, including EVOH resins. 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 and reusing them, and is expected to be a recycling method that can further reduce the environmental impact.Moreover, 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 olefin-based plastics and a specific amount of 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 found that when plastic waste containing EVOH resin is thermally decomposed to produce an oil-derived composition as disclosed in Patent Document 1, not only the desired hydrocarbons are contaminated but also oxygen-containing compounds, which are formed by decomposing high-molecular-weight plastics. These oxygen-containing compounds can cause corrosion of equipment or inhibit decomposition when naphtha containing the oil-derived composition is subjected to naphtha cracking (cracking). Therefore, a need exists for a method for producing an oil-derived composition that increases the proportion of hydrocarbons and shortens the thermal decomposition time.

[0008] Therefore, the present invention provides a method for producing an oil composition that has a high hydrocarbon content and can shorten the thermal decomposition time.

[0009] In view of the above circumstances, the present inventors have found that the above problems can be solved by thermally decomposing a resin composition containing an EVOH resin under two-stage conditions.

[0010] That is, the present invention has the following aspects. [1] A method for producing an oil-based composition, comprising: a first step of heating a resin composition containing an EVOH resin (A) at a temperature of 240°C to 450°C, and then maintaining the composition at a temperature within a range of the heating temperature ±30°C to remove the resulting gas; and a second step of heating the composition at a temperature higher than the heating temperature in the first step and exceeding 400°C. [2] A method for producing an oil-based composition according to [1], wherein the heating temperature in the first step is 300°C to 430°C. [3] A method for producing an oil-based composition according to [1] or [2], wherein the heating temperature in the second step is higher than 400°C and not higher than 600°C. [4] A method for producing an oil-based composition according to any of [1] to [3], wherein the heating time in the first step is 5 minutes or more and less than 60 minutes. [5] A method for producing an oil-based composition according to any of [1] to [4], wherein the heating time in the second step is 10 minutes or more and not more than 45 minutes. [6] The method for producing an oil-based composition according to any one of [1] to [5], wherein the proportion of hydrocarbons contained in the oil-based composition is 50% by mass or more based on the total mass of the oil-based composition. [7] The method for producing an oil-based composition according to any one of [1] to [6], wherein hydrocarbons are recovered in the second step. [8] The method for producing an oil-based composition according to any one of [1] to [7], wherein a distillation step is performed after the second step. [9] The method for producing an oil-based composition according to [8], wherein the distillation step is performed at a pressure of 100 mmHg to 760 mmHg and a temperature of 70°C to 250°C in the distillation step.

[10] A chemical recycling method using the method for producing an oil-based composition according to any one of [1] to [9].

[11] A method for producing recycled chemical raw materials, wherein naphtha containing an oil-based composition obtained by the method for producing an oil-based composition according to any one of [1] to [9] is subjected to naphtha cracking to obtain recycled chemical raw materials.

[12] The method for producing recycled chemical raw materials according to

[11] , wherein the recycled chemical raw materials are ethylene and / or propylene.

[13] 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

[11] or

[12] to obtain a polymer.

[14] 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

[13] to obtain a molded article.

[0011] The production method of the present invention can shorten the thermal decomposition time, and the oil composition obtained by the production method of the present invention can increase the hydrocarbon content by reducing the content of impurities such as oxygen-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, and even more preferably 70% 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 "this production method") comprises a first step of heating a resin composition containing EVOH resin (A) at a temperature of 240°C to 450°C, and then removing the resulting gas by maintaining the temperature within a temperature range of ±30°C from the heating temperature, and a second step of heating the composition at a temperature higher than the heating temperature in the first step and exceeding 400°C. Before describing this production method, the resin composition will be described below.

[0015] <Resin Composition> The resin composition is not particularly limited as long as it contains the EVOH resin (A).

[0016] [EVOH Resin (A)] The EVOH resin (A) used in the present production method 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) is not particularly limited, but is usually 0.1% by mass to 90% by mass, preferably 1% by mass to 50% by mass, and particularly preferably 5% by mass to 20% by mass, based on the total mass of the resin composition.

[0026] The resin composition may contain a thermoplastic resin other than the EVOH resin (A) or a compounding agent, i.e., the resin composition may be a thermoplastic resin composition containing the EVOH resin (A).

[0027] [Thermoplastic Resin Other Than EVOH Resin] Examples of the thermoplastic resin other than the EVOH resin (A) include known thermoplastic resins, for example, polyethylene resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, and polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain); and the like. Examples of suitable polyolefin resins include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins in which fats are graft-modified with unsaturated carboxylic acids or their esters; ionomers; ethylene-vinyl acetate copolymers; ethylene-acrylic acid copolymers; ethylene-acrylic acid ester copolymers; polyester resins; polyamide resins (including copolymerized polyamides); polyvinyl chloride; polyvinylidene chloride; acrylic resins; polystyrene resins; vinyl ester resins; polyester elastomers; polyurethane elastomers; polystyrene elastomers; halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene; and aromatic or aliphatic polyketones. These may be used alone or in combination of two or more. Among these, polyolefin resins and polyamide resins are preferred, with polyethylene resins and polypropylene resins being more preferred. 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.

[0028] When the resin composition contains a thermoplastic resin other than the EVOH resin (A), the content thereof is usually 1 to 90% by mass, preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass, based on the total mass of the resin composition.

[0029] [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.

[0030] 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.

[0031] 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.

[0032] [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.

[0033] 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).

[0034] 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 "EVOH resin layer"), or may be a multi-layer molded article consisting of an EVOH resin layer and a base resin layer containing a thermoplastic resin other than EVOH resin as a main component (hereinafter the resin used for the base resin will be referred to as "base resin"). Examples of the base resin include the above-mentioned thermoplastic resins other than EVOH resin.

[0035] The multilayer laminate may have a plurality of EVOH resin layers and base resin layers, and further, an adhesive resin layer containing an adhesive resin may be interposed between the EVOH resin layer and the base resin layer, if necessary.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The resin composition may be subjected to a cutting treatment or a pulverization treatment before being subjected to the first step. 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.

[0040] In this production method, the resin composition is thermally decomposed by the method described below to obtain a thermal decomposition product. However, if the resin composition contains a thermoplastic resin containing chlorine, such as polyvinyl chloride, it is preferable to perform a desalination treatment before the thermal decomposition.

[0041] Examples of the desalting method include the well-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 the present production method.

[0042] <Present Production Method> This production method comprises a first step of heating a resin composition containing EVOH resin (A) at a temperature of 240°C to 450°C, followed by maintaining the temperature within a range of ±30°C from the heating temperature and removing the resulting gas, and a second step of heating the resin composition at a temperature higher than the heating temperature in the first step and exceeding 400°C. That is, this production method involves a first-stage thermal decomposition (carried out at 240°C to 450°C and maintained within a range of ±30°C), followed by a second-stage thermal decomposition at a temperature higher than the first stage and exceeding 400°C. Typically, an oil-derived composition obtained by thermally decomposing a resin composition containing EVOH resin (A) contains, in addition to hydrocarbons, oxygen-containing compounds produced by the degradation of the polymer components contained in the EVOH resin (A). When these oxygen-containing compounds are present in large amounts, they tend to cause equipment corrosion and inhibit decomposition during naphtha cracking of the resulting oil-derived composition. Therefore, in the present invention, a large amount of oxygen-containing compounds is generated in the first thermal decomposition stage (first step), and these are separated to increase the hydrocarbon content in the oil composition obtained after the second step, i.e., to reduce the content of impurities such as oxygen-containing compounds in the oil composition. The term "hydrocarbon" refers to compounds that do not contain heteroatoms and are composed only of carbon and hydrogen, such as ethylene and propylene. This production method is described in detail below.

[0043] 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 a cooler for cooling the resulting gas or a flocculation means for flocculating the gas from the pyrolysis tank to produce oil.

[0044] 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.

[0045] [(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.

[0046] 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.

[0047] 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.

[0048] In addition, from the viewpoint of thermal decomposition efficiency, it is preferable to carry out the decomposition of the resin composition while stirring.

[0049] [(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.

[0050] 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).

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Examples of the carrier gas include rare gases such as helium, nitrogen, and carbon dioxide.

[0055] 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.

[0056] In addition, from the viewpoint of thermal decomposition efficiency, it is preferable to carry out the decomposition of the resin composition while stirring.

[0057] (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.

[0058] 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.

[0059] The treatment conditions are those generally used in fluid catalytic cracking of petroleum. For example, the reactor pressure is about 0.1 to 3.0 kg / 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.

[0060] This production method is a method (i) to (iii) that includes a first step of heating at a temperature of 240°C to 450°C, and then removing the gas obtained by maintaining the temperature within a temperature range of the heating temperature ±30°C, and a second step of heating at a temperature higher than the heating temperature in the first step and exceeding 400°C.

[0061] [First Step] The first step involves heating at a temperature in the range of 240°C to 450°C, maintaining the temperature, and removing the resulting gas. Oxygen-containing compounds, which cause equipment corrosion and decomposition inhibition when naphtha containing an oil-containing composition is subjected to naphtha cracking treatment, are generated when plastics containing EVOH resin are thermally decomposed in a specific temperature range. Therefore, in this production method, the resin composition is heated in a specific temperature range of 240°C to 450°C to preferentially generate oxygen-containing compounds, which are then separated first, thereby reducing the oxygen-containing compound content.

[0062] The heating temperature (including the temperature at which it is maintained) in the first step may be in the range of 240° C. to 450° C., and from the viewpoint of being able to generate a large amount of oxygen-containing compounds in particular, it is preferable to raise the temperature to a temperature range of 300° C. to 430° C., more preferably 310° C. to 420° C., even more preferably 320° C. to 410° C., and particularly preferably 340° C. to 400° C. If the temperature after heating is within the above range, oxygen-containing compounds can be efficiently generated in the first step, the proportion of oxygen-containing compounds, etc. contained in the oil-based composition can be reduced, and the content of hydrocarbon compounds can be increased.

[0063] The heating time in the first step refers to the sum of the temperature rise time and the holding time in the temperature range of 240°C to 450°C. Thus, in the first step, the temperature is raised in the temperature range of 240°C to 450°C, and when a specific temperature is reached, that temperature is maintained, thereby enabling two-stage pyrolysis. The heating time in the first step is preferably 5 minutes or more and less than 60 minutes, more preferably 7 minutes or more and 50 minutes or less, and particularly preferably 10 minutes or more and 40 minutes or less. Furthermore, the temperature rise time is preferably 3 minutes or more and 50 minutes or less, and the holding time is preferably 2 minutes or more and 30 minutes or less. When the heating time is within the above range, the yield of the oil-based composition tends to be increased, and the oxygen-containing compounds contained in the oil-based composition also tends to be sufficiently reduced.

[0064] In this production method, the gas containing a large amount of oxygen-containing compounds generated in the first step is separated from the pyrolysis product obtained in the second step described below by known means, thereby increasing the proportion of hydrocarbons contained in the oil composition obtained after the second step. The gas obtained in the first step may be separated as a gas by known means, or the gas may be cooled to a temperature below the dew point and separated as a liquid.

[0065] [Second Step] The second step is a step in which heating is performed at a temperature higher than the heating temperature in the first step, exceeding 400°C. It is also preferable to recover hydrocarbons in this second step. In this production method, the second step begins from the point in time when the temperature is raised and maintained in the heating of the first step, and then raised again.

[0066] The heating temperature in the second step is higher than that in the first step and exceeds 400°C, preferably exceeds 400°C and is not higher than 600°C, more preferably 430°C to 590°C, still more preferably 440°C to 580°C, and particularly preferably 450°C to 550°C. When the heating temperature in the second step is within the above range, the efficiency of pyrolysis tends to be excellent.

[0067] The heating time in the second step refers to the time during which the mixture is heated to a temperature higher than that in the first step and above 400°C. In the second step, it is necessary to raise the temperature to a higher temperature than in the first step, but it is not necessary to provide a holding time. The heating time in the second step is preferably 10 minutes or more and 45 minutes or less, more preferably 20 minutes or more and 40 minutes or less. When the heating time is within the above range, the efficiency of pyrolysis tends to be excellent.

[0068] A pyrolysis product (oil composition) can be obtained by recovering the hydrocarbon-containing gas obtained in the second step. The hydrocarbon-containing gas obtained in the second step may be liquefied by cooling it to a temperature below the dew point of the cracked gas using a known flocculation means, and then recovered.

[0069] When the apparatus used in this production method is equipped with a cooler, it is also preferable to cool the gas obtained in the first and second steps 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 in the first and second steps with the cooler, gas components having a boiling point higher than the temperature of the cooler are liquefied and returned to the pyrolysis tank, which tends to reduce the amount of impurities contained in the gas.

[0070] Furthermore, the oil-forming composition obtained by the method (ii) tends to be acidic because it contains components derived from the iron pyroacetate solution. Therefore, if the oil-forming composition is acidic, it is preferable to neutralize it. Known methods can be used as the neutralization method.

[0071] Furthermore, in the first and second steps, catalytic cracking is preferably carried out using a catalyst.

[0072] Examples of the catalyst include FCC catalysts and FCC waste catalysts, which may be used alone or in combination of two or more.

[0073] 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.

[0074] The average particle size of the FCC catalyst and FCC waste catalyst is usually 40 μm to 80 μm.

[0075] 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.

[0076] [Distillation Step] The pyrolysate (oil composition) obtained in the second step is preferably distilled to remove impurities such as water, tar, etc. That is, the present production method preferably includes a distillation step after the second step.

[0077] The distillation conditions in the distillation step are, for example, preferably a pressure of 100 mmHg to 760 mmHg and a distillation temperature of 70° C. to 250° C., more preferably 80° C. to 230° C., and even more preferably 90° C. to 210° C. When the distillation conditions are within the above ranges, an oil-based composition with fewer impurities tends to be obtained.

[0078] The pyrolysate (oil composition) obtained in the second step may be centrifuged to remove impurities such as water and tar.

[0079] The oil composition obtained by this production method is preferably 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 can be further reduced.

[0080] The content of the thermal decomposition product of the resin composition in the entire oil-based composition is usually 10% by mass or more, preferably 30% by mass or more, and particularly preferably 50% by mass or more.

[0081] The proportion of hydrocarbons contained in the oil composition is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total mass of the oil composition.

[0082] The proportion of hydrocarbons contained in the oil-based composition can be determined by measuring using GC / MS.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] As described above, the embodiment of the present invention can shorten the thermal decomposition time required to obtain an oil composition from a resin composition containing EVOH resin. Furthermore, since the obtained oil composition has a high hydrocarbon content, recycled chemical raw materials and subsequent polymers and molded articles can be stably obtained. Therefore, the embodiment of the present invention is suitable as a chemical recycling method.

[0089] 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.

[0090] The materials used in the following examples and comparative examples are as follows: 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, saponification degree 99.9 mol% Polyethylene (B): Novatec (registered trademark) UF240 manufactured by Japan Polyethylene Corporation, MFR (190°C, load 2160 g) 2.1 g / 10 min, density 0.920 g / cm 3 Adhesive resin (C): "Plexar (registered trademark) PX3236" manufactured by LyondellBasell, MFR (190 ° C, load 2160 g) 2.0 g / 10 min, density 0.922 g / cm 3

[0091] [Production of Multilayer Structure (Resin Composition)] EVOH resin (A), polyethylene (B), and adhesive resin (C) were supplied to a multilayer coextrusion film-forming apparatus and subjected to multilayer coextrusion molding under the following conditions to obtain a multilayer structure (resin composition) having a three-type, five-layer structure of (B) layer / (C) layer / (A) layer / (C) layer / (B layer). The thicknesses (μm) of the layers in the multilayer structure (resin composition) were 40 / 5 / 10 / 5 / 40. The content of the EVOH resin was 10% of the total resin composition.

[0092] [Multi-layer co-extrusion molding conditions] (A) layer extruder: 40 mmφ single-screw extruder (barrel temperature: 210°C) (B) layer extruder: 40 mmφ single-screw extruder (barrel temperature: 230°C) (B) layer extruder: 50 mmφ single-screw extruder (barrel temperature: 230°C) (B) layer extruder: 32 mmφ single-screw extruder (barrel temperature: 230°C) (C) layer extruder: 32 mmφ single-screw extruder (barrel temperature: 210°C) Die: 5-type 7-layer feedblock type T-die Take-up speed: 11 m / min Roll temperature: 80°C

[0093] Example 1: 2 mg of the multilayer structure (resin composition) was weighed into a platinum boat and placed in a TPD-MS. The boat was heated from 240°C to 400°C over 8 minutes at a heating rate of 20°C / min under a helium gas atmosphere, and then held at 400°C for 10 minutes to recover the generated decomposition gas (first step). The temperature change during this holding period was within ±30°C. The resulting mixture was then heated at 500°C for 35 minutes to completely decompose the resin, yielding a gaseous oil-based composition containing a thermal decomposition product of the EVOH resin (second step). Here, "completely decomposed" refers to the point at which no gas generation was detected during the heating period.

[0094] Example 2 2 mg of the multilayer structure (resin composition) was weighed into a platinum boat and placed in a TPD-MS. The boat was heated from 240°C to 350°C over 5.5 minutes at a heating rate of 20°C / min under a helium gas atmosphere, and then held at 350°C for 30 minutes to recover the generated decomposition gas (first step). The temperature change during this holding period was within ±30°C. The resulting mixture was then heated at 500°C for 15 minutes to completely decompose the mixture, yielding a gaseous oil composition containing a thermal decomposition product of the EVOH resin (second step).

[0095] Comparative Example 1 2 mg of the multilayer structure (resin composition) was weighed into a platinum boat and placed in a TPD-MS. The boat was heated to 500°C at a heating rate of 20°C / min over 13 minutes in a helium gas atmosphere, and then heated at 500°C for 35 minutes to completely pyrolyze the structure without carrying out the second step, thereby obtaining a gaseous oil composition containing a pyrolyzate of the EVOH resin.

[0096] Comparative Example 2 2 mg of the multilayer structure (resin composition) was weighed into a platinum boat and placed in a TPD-MS. The boat was heated to 350°C over 5.5 minutes at a heating rate of 20°C / min in a helium gas atmosphere, and then heated at 350°C for 65 minutes to completely pyrolyze the structure without carrying out the second step, thereby obtaining a gaseous oil composition containing a pyrolyzate of the EVOH resin.

[0097] The hydrocarbon content and oxygen atom content of the gaseous oil compositions obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were measured according to the methods described below. The results are shown in Table 1.

[0098] [Ratio of Hydrocarbon Content] The composition of the gaseous oil composition was analyzed using GC / MS, and the ratio of hydrocarbons in all the generated fragments was calculated.

[0099]

[0100] From the results in Table 1, the oil compositions obtained by the production methods of Examples 1 and 2 had hydrocarbon contents of 90% or more and contained small amounts of other impurities that could cause equipment corrosion or cracking inhibition during naphtha cracking. On the other hand, the oil composition obtained by the production method of Comparative Example 1 had a low hydrocarbon content of 70%, which is thought to cause equipment corrosion or cracking inhibition during naphtha cracking. Furthermore, the production method of Comparative Example 2 took a long time of 70.5 minutes to achieve complete thermal decomposition, indicating poor thermal decomposition efficiency.

[0101] 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.

[0102] This production method achieves a high hydrocarbon content and shortens the thermal decomposition time. Furthermore, since the obtained oil composition has a high hydrocarbon content, it is less likely to cause corrosion of equipment or inhibit decomposition during naphtha cracking treatment, making it suitable for chemical recycling.

Claims

1. A method for producing an oil-based composition, comprising: a first step of heating a resin composition containing an ethylene-vinyl alcohol copolymer (A) at a temperature of 240°C to 450°C, and then maintaining the composition at a temperature within a range of ±30°C from the heating temperature to remove the resulting gas; and a second step of heating the composition at a temperature higher than the heating temperature in the first step, exceeding 400°C.

2. The method for producing an oil-based composition according to claim 1, wherein the heating temperature in the first step is 300°C to 430°C.

3. The method for producing an oil-based composition according to claim 1 or 2, wherein the heating temperature in the second step is higher than 400°C and not higher than 600°C.

4. The method for producing an oil-based composition according to claim 1 or 2, wherein the heating time in the first step is 5 minutes or more and less than 60 minutes.

5. The method for producing an oil-based composition according to claim 1 or 2, wherein the heating time in the second step is from 10 minutes to 45 minutes.

6. The method for producing an oil composition according to claim 1 or 2, wherein the proportion of hydrocarbons contained in said oil composition is 50 mass % or more based on the total mass of the oil composition.

7. The method for producing an oil composition according to claim 1 or 2, wherein hydrocarbons are recovered in the second step.

8. The method for producing an oil composition according to claim 1 or 2, further comprising a distillation step after the second step.

9. The method for producing an oil composition according to claim 8, wherein the distillation step is carried out at a pressure of 100 mmHg to 760 mmHg and a temperature of 70°C to 250°C.

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

11. A method for producing recycled chemical raw materials, comprising 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 9 to naphtha cracking treatment to obtain recycled chemical raw materials.

12. The method for producing renewable chemical raw materials according to claim 11, wherein the renewable chemical raw materials are ethylene and / or propylene.

13. 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 11 to obtain a polymer.

14. 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 13 to obtain a molded article.

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