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

Abstract

To provide an oil composition having low content ratios of a nitrogen-containing compound and a chlorine-containing compound.SOLUTION: An oil composition contains a hydrogenated thermal decomposition product of a resin composition containing an ethylene-vinyl alcohol copolymer, wherein a ratio of an oxygen atom contained in the oil composition is 1 mass% or less with respect to the oil composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-based composition, 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 an oil-based composition in which the content of impurities such as nitrogen-containing compounds and chlorine-containing compounds contained in the oil-based composition is reduced, 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. [Background technology]

[0002] Ethylene-vinyl alcohol copolymers (hereinafter sometimes referred to as "EVOH resins") have excellent transparency, gas barrier properties such as oxygen, aroma retention, solvent resistance, oil resistance, and mechanical strength, and are molded into films, sheets, bottles, etc., 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, including EVOH resins, in order to make effective use of resources. Thermal recycling, chemical recycling, and material recycling are known methods for recycling such 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-based 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 the decomposition oil or decomposition gas is recovered. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-345894 Summary of the Invention [Problem to be solved by the invention]

[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 impurities such as nitrogen-containing compounds and chlorine-containing compounds, which are formed by decomposing high-molecular-weight plastics. These impurities, such as nitrogen-containing compounds and chlorine-containing compounds, can cause corrosion of equipment and inhibit decomposition when the oil-derived composition is subjected to naphtha cracking treatment (cracking). Therefore, it is believed that there is a demand for an oil-derived composition with a low content of impurities such as nitrogen-containing compounds and chlorine-containing compounds.

[0008] Therefore, an object of the present invention is to provide an oil-based composition having a low content of nitrogen-containing compounds and chlorine-containing compounds, a method for producing the 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. [Means for solving the problem]

[0009] In view of the above circumstances, the present inventors have found that the above problems can be solved by subjecting a resin composition containing an EVOH resin to a hydrogenated pyrolysis product.

[0010] That is, the present invention has the following aspects. [1] An oil-based composition containing a hydrothermal decomposition product of a resin composition containing an EVOH resin, wherein the proportion of oxygen atoms contained in the oil-based composition is 1% by mass or less based on the mass of the oil-based composition. [2] The oil-forming composition according to [1], wherein the ratio of nitrogen atoms contained in the oil-forming composition is 0.3 mass % or less based on the mass of the oil-forming composition. [3] The oil-forming composition according to [1] or [2], wherein the proportion of chlorine atoms contained in the oil-forming composition is 1 ppm or less relative to the oil-forming composition. [4] The oil-forming composition according to any one of [1] to [3], wherein the hydrogenation rate of the hydrothermal decomposition product is 70% or more. [5] A method for producing an oil-based composition containing a hydrogenated pyrolysate of a resin composition containing an EVOH resin, the method comprising the steps of: thermally decomposing a resin composition containing an EVOH resin to obtain a pyrolysate; and hydrogenating the pyrolysate to obtain a hydrogenated pyrolysate. [6] The method for producing an oil-based composition according to [5], wherein the temperature of the thermal decomposition is 240°C to 800°C. [7] The method for producing an oil-forming composition according to [5] or [6], further comprising a distillation step after the step of obtaining the thermal decomposition product. [8] The method for producing an oil-forming composition according to [7], wherein the distillation step is carried out under a pressure of 100 mmHg to 760 mmHg and at a temperature of 70°C to 250°C. [9] The method for producing an oil-based composition according to any one of [5] to [8], wherein the proportion of oxygen atoms contained in the oil-based composition is 1 mass % or less based on the mass of the oil-based composition.

[10] The method for producing an oil-based composition according to any one of [5] to [9], wherein the proportion of chlorine atoms contained in the oil-based composition is 1 ppm or less relative to the oil-based composition.

[11] The method for producing an oil-forming composition according to any one of [5] to

[10] , wherein the hydrogenation rate of the hydrothermal decomposition product is 70% or more.

[12] A chemical recycling method using the method for producing an oil-based composition according to any one of [5] to

[11] .

[13] 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 [5] to

[11] to naphtha cracking treatment to obtain recycled chemical raw materials.

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

[13] , wherein the recycled chemical raw material is ethylene and / or propylene.

[15] 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

[13] or

[14] to obtain a polymer.

[16] 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

[15] to obtain a molded article. [Effects of the Invention]

[0011] The oil-based composition and the method for producing the oil-based composition of the present invention can reduce the proportion of nitrogen-containing compounds and chlorine-containing compounds contained in the oil-based composition. DETAILED DESCRIPTION OF THE INVENTION

[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 configurations)" means at least one of X and Y, and means three possibilities: X only, Y only, and X and Y. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, 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 it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means "preferably more than X" or "preferably less than Y." In the present specification, when numerical ranges are described in stages, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, 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.

[0014] An oil-based composition according to one embodiment of the present invention (hereinafter sometimes referred to as "the oil-based composition") contains a hydrogenated pyrolysis product of a resin composition containing an EVOH resin, and the proportion of oxygen atoms contained in the oil-based composition is a specific amount or less relative to the oil-based composition.

[0015] The content of the hydrogenated pyrolysate in the present oil-forming composition is usually 90% by mass or more, preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0016] This oil-refining composition is usually subjected to naphtha cracking treatment (decomposition), and the ethylene contained therein is separated and recovered, and used as a recycled resource. However, it has been found that when a resin composition containing an EVOH resin is thermally decomposed, if the resin contains a certain amount or more of oxygen-containing compounds generated by the degradation of the polymer components contained in the EVOH resin, the proportion of nitrogen-containing compounds and chlorine-containing compounds contained in the hydrogenation pyrolyzed product of the resin composition also increases.In the present invention, the amounts of these nitrogen-containing compounds and chlorine-containing compounds are reduced.

[0017] The hydrogenation rate of the above-mentioned hydrothermal decomposition product is usually 70% or more, preferably 80% or more, and particularly preferably 90% or more of saturated bonds.

[0018] The content of oxygen-containing compounds in the oil-based composition can be considered as the content of oxygen atoms, and is 1% by mass or less, preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on the oil-based composition. There is no particular lower limit, and the lower the content, the better. When the content of oxygen atoms is within the above range, the content of nitrogen-containing compounds and chlorine-containing compounds in the oil-based composition tends to be further reduced.

[0019] Furthermore, nitrogen-containing compounds, chlorine-containing compounds, etc. contained in the oil-refining composition tend to cause corrosion of equipment and inhibit decomposition during the subsequent naphtha cracking treatment.

[0020] The proportion of nitrogen-containing compounds contained in the present oil-forming composition can be considered as the content ratio of nitrogen atoms, and from the viewpoint of preventing corrosion of equipment and inhibition of decomposition during naphtha cracking treatment, the proportion of nitrogen atoms contained in the present oil-forming composition is preferably 0.3 mass% or less, more preferably 0.2 mass% or less, and particularly preferably 0.1 mass% or less, relative to the oil-forming composition. There is no particular lower limit, and the lower the better.

[0021] The proportion of chlorine-containing compounds contained in the present oil-forming composition can be considered as the content ratio of chlorine atoms, and from the viewpoint of preventing corrosion of equipment and inhibition of decomposition during naphtha cracking treatment, the proportion of chlorine atoms contained in the present oil-forming composition is preferably 1 ppm or less, more preferably 0.8 ppm or less, and particularly preferably 0.5 ppm or less, relative to the oil-forming composition. There is no particular lower limit, and the lower the better.

[0022] The proportions of oxygen atoms, nitrogen atoms, and chlorine atoms contained in the present oil-based composition can be determined, for example, by measurement using an elemental analyzer.

[0023] Such an oil-based composition of the present invention can be obtained, for example, by a production method (hereinafter referred to as "the production method of the present invention") that includes the steps of thermally decomposing a resin composition containing an EVOH resin to obtain a thermal decomposition product, and hydrogenating the thermal decomposition product to obtain a hydrogenated thermal decomposition product. This manufacturing method will now be described.

[0024] [Resin composition] First, the resin composition used in this production method will be described. The resin composition is not particularly limited as long as it contains an EVOH resin.

[0025] [EVOH resin] The EVOH resin used in this 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.

[0026] 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-based 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, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms, are used. These are typically used alone, but multiple types may be used simultaneously as needed.

[0027] The copolymerization of ethylene and vinyl ester monomers can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., but solution polymerization using methanol as a solvent is generally used. The ethylene-vinyl ester copolymer obtained can also be saponified by a known method. The EVOH resin produced in this manner is mainly composed of structural units derived from ethylene and vinyl alcohol structural units, and also contains a small amount of vinyl ester structural units that remain unsaponified.

[0028] The content of ethylene structural units in the EVOH resin is preferably 20 mol % to 60 mol %, more preferably 25 mol % to 50 mol %, and particularly preferably 25 mol % to 35 mol %. The content of the ethylene structural units can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene. The content of ethylene structural units is usually 1 It is measured by H-NMR measurement. For example, 1 H-NMR measurement is performed using DMSO-d6 as the measurement solvent at a measurement temperature of 50°C.

[0029] The saponification degree of the EVOH resin is preferably 90 mol % to 100 mol %, more 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 a saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used when saponifying an ethylene-vinyl ester copolymer. The saponification degree of such an EVOH resin is usually determined by the content of ethylene structural units, as follows: 1 It is measured by H-NMR measurement. For example, 1 H-NMR measurement is performed using DMSO-d6 as the measurement solvent at a measurement temperature of 50°C.

[0030] The melt flow rate (MFR) of the EVOH resin (210°C, load 2160g) is usually 0.5g / 10 minutes to 100g / 10 minutes, preferably 1g / 10 minutes to 50g / 10 minutes, and particularly preferably 3g / 10 minutes to 35g / 10 minutes. The MFR is an index of the degree of polymerization of the EVOH resin, and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene with a vinyl ester monomer.

[0031] The EVOH resin may further contain structural units derived from the comonomers shown below (for example, 10 mol % or less of the EVOH resin) 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 acylates; 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. 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 dialkyl 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 its quaternary salts acrylamides such as methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidepropyldimethylamine or its acid salt or its quaternary salt; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, 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.

[0032] Furthermore, as the EVOH resin, a "post-modified" EVOH resin such as esterified, urethane-modified, acetalized, cyanoethylated, or oxyalkylenated can also be used.

[0033] Furthermore, the EVOH resin may be a mixture of EVOH resins having different ethylene structural unit contents, saponification degrees, polymerization degrees, copolymerization components, and the like.

[0034] The content of the EVOH resin 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.

[0035] The resin composition may contain a thermoplastic resin other than the EVOH resin and a compounding agent, that is, the resin composition may be a thermoplastic resin composition containing an EVOH resin.

[0036] [Thermoplastic resins other than EVOH resins] Examples of thermoplastic resins other than the EVOH resin include known thermoplastic resins, for example, polyethylene-based 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-based resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin-based resins such as polybutene, polypentene, and polycyclic olefin-based resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain); and these polyolefin-based resins. Examples of the polyolefin resin include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by graft-modifying an olefin resin with an unsaturated carboxylic acid or its ester; 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, polyamide resins are 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.

[0037] When the resin composition contains a thermoplastic resin other than the EVOH resin, the content thereof is usually 0.1% by mass to 90% by mass, preferably 1% by mass to 80% by mass, and particularly preferably 2% by mass to 70% by mass, based on the total resin composition.

[0038] [Combined ingredients] Examples of the compounding agents include compounding agents that are generally compounded with 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.

[0039] 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; polyhydric phenols such as ascorbic acid, fatty acid esters and metal salts of ascorbic acid, gallic acid, and 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), an antioxidant other than those mentioned above, or a deodorizer (e.g., activated carbon) to these blends.

[0040] 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.

[0041] [Shape of resin composition] The shape of the resin composition is not particularly limited, and examples thereof include pellets, films, sheets, molded bodies, and crushed products, broken materials, irregular products, and the like obtained by crushing these.

[0042] 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).

[0043] 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 an EVOH resin (hereinafter referred to as an "EVOH resin layer"), or a multi-layer molded article consisting of an EVOH resin layer and a substrate resin layer containing a thermoplastic resin other than EVOH resin as a main component (hereinafter the resin used for the substrate will be referred to as the "substrate resin"). Examples of the substrate resin include the above-mentioned thermoplastic resins other than EVOH resin.

[0044] 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.

[0045] 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 an anhydride thereof to a polyolefin resin by addition reaction, graft reaction, or the like.

[0046] 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) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin resin, maleic anhydride graft-modified polyolefin resin, etc. These may be used alone or in combination of two or more.

[0047] When the resin composition is in the form of a molded article, the molded article may be a molded article made of a single-layer film or a molded article made of a multi-layer film.

[0048] Furthermore, 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 crushing treatment is not particularly limited. The cutting method may be, for example, a method of cutting with a cutting machine such as a slitter or a shredder. Examples of the pulverization method include pulverization using a pulverizer, and 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 and pulverization methods may be used alone or in combination of two or more.

[0049] In this production method, the resin composition is first thermally decomposed to obtain a thermal decomposition product. However, if the resin composition contains a thermoplastic resin containing chlorine, such as vinyl chloride, it is preferable to perform a desalination treatment before the thermal decomposition.

[0050] The desalting method may be 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.

[0051] [Step of obtaining thermal decomposition product] The step of thermally decomposing the resin composition to obtain a thermal decomposition product will be described.

[0052] The temperature at which the thermal decomposition is carried out is preferably 240° C. to 800° C., more preferably 250° C. to 600° C., and particularly preferably 300° C. to 500° C. When the heating temperature is within the above range, the contents of nitrogen-containing compounds and chlorine-containing compounds contained in the oil-based composition tend to be reduced.

[0053] The apparatus used in the step of obtaining the pyrolysate is not particularly limited, and examples thereof include apparatuses that are typically used for converting polyolefin-based resins into oil, such as an apparatus equipped with a pyrolysis tank for gasifying a resin composition and a coagulation means for cooling the decomposition gas from the pyrolysis tank to produce oil.

[0054] 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. These methods are described below.

[0055] [(i) Decomposition method using an electric furnace] The method of decomposing using an electric furnace may involve filling the resin composition in an electric furnace (thermal decomposition tank) equipped with a heater and heating it with the heater.

[0056] The heating temperature is usually 200°C to 800°C, preferably 250°C to 600°C, and particularly preferably 300°C to 500°C. When the heating temperature is within this range, the contents of nitrogen-containing compounds and chlorine-containing compounds contained in the oil-containing composition tend to be reduced. Furthermore, when the temperature is equal to or higher than the lower limit, the decomposition time tends to be shortened, and when the temperature is equal to or lower than the upper limit, the wax content in the obtained pyrolyzate tends to be reduced.

[0057] 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, and the heating time may be continued until the resin composition is completely thermally decomposed, but is usually 24 hours, preferably 12 hours, more preferably 6 hours.

[0058] 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 stages, the conditions are preferably, for example, such that in the first stage, the material is heated at 240°C to 450°C, the resulting gas is removed, and then the material is heated to a temperature higher than in the first stage, exceeding 400°C, to cause complete pyrolysis (second stage heating).

[0059] 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.

[0060] Examples of the carrier gas include rare gases such as helium, nitrogen, carbon dioxide, etc. Among these, nitrogen is preferred.

[0061] 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, it is 0.05 L / min to 0.5 L / min.

[0062] The method of cracking using an electric furnace is also preferably catalytic cracking using a catalyst.

[0063] Examples of the catalyst include FCC catalysts and spent FCC catalysts, which may be used alone or in combination of two or more.

[0064] The FCC catalyst is a synthetic zeolite-based solid acid catalyst used in the fluid catalytic cracking (FCC) process of petroleum, and is composed mainly of Al2O3, to which small amounts of Na, Fe, C, V, Ni, Sb, etc. are blended. The spent FCC catalyst is the FCC catalyst that has been regenerated. 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, and therefore can be thoroughly mixed with the resin composition in the pyrolysis tank.

[0065] The average particle size of the FCC catalyst and FCC waste catalyst is usually 40 μm to 80 μm.

[0066] 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.

[0067] The decomposed resin composition is gasified to generate a decomposition gas, which can be recovered to obtain a pyrolyzed product. The cracked gas may be recovered after being liquefied by cooling it to a temperature below the dew point of the cracked gas using a known agglomeration means.

[0068] In addition, when the apparatus used in the method of decomposing using an electric furnace is equipped with a cooler, it is also preferable to cool the obtained decomposition gas with the cooler. For example, it is also preferable to cool the gaseous oil composition obtained by the first heating, the 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. in 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.

[0069] [(ii) Decomposition method using iron pyroacetate solution] An example of a method for decomposing the resin composition using an iron pyroacetate solution is a method in which the resin composition is decomposed by bringing the iron pyroacetate solution heated under normal pressure in the absence of air into contact with the resin composition in a pyrolysis tank.

[0070] The pyroligneous acid is the supernatant of the dry distillation liquid produced when wood is dry distilled, and the iron pyroligneous acid solution is a liquid with a pH of 1.5 to 7 obtained by dissolving iron in pyroligneous acid. The pyroligneous acid contains wood-derived organic acids (such as acetic acid), alcohols, carbonyl compounds, and aromatic compounds (such as phenols and furans).

[0071] The temperature of the pyrolyzed iron acetate solution is preferably 240°C to 800°C, more preferably 300°C to 500°C, even 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 contents of nitrogen-containing compounds and chlorine-containing compounds contained in the oil-forming composition tend to be reduced. If the temperature is too low, the decomposition time tends to be long. If the temperature is too high, the wax content in the resulting pyrolyzed product tends to be high.

[0072] From the viewpoint of thermal decomposition efficiency, the amount of the iron pyroacetate liquid 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.

[0073] The amount of the ferric pyroacetate liquid is preferably 20% by volume 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 make the work more complicated.

[0074] 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.

[0075] Examples of the carrier gas include rare gases such as helium, nitrogen, and carbon dioxide.

[0076] 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, it is 0.05 L / min to 0.5 L / min.

[0077] The decomposed resin composition is gasified to generate a decomposition gas, which can be recovered to obtain a pyrolyzed product. The cracked gas may be recovered after being liquefied by cooling it to a temperature below the dew point of the cracked gas using a known flocculation means.

[0078] Furthermore, the pyrolyzate of the resin composition obtained by this method tends to be acidic because it contains components derived from the iron pyroacetate solution. 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.

[0079] [(iii) Decomposition method using a fluidized bed contactor] The fluidized bed contactor may be a device commonly used in the field of petroleum refining, and basically comprises a reaction tower (reactor), a catalyst / product oil separator, a section for removing oil from the catalyst surface, and a catalyst regeneration tower, with the catalyst circulating in a fluidized bed within the system.

[0080] 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 MW Kellogg, and the R2R type from IFP.

[0081] As for the treatment conditions, the reactor temperature is usually 240° C. to 800° C., preferably 250° C. to 600° C., and particularly preferably 300° C. to 500° C. When the temperature is within the above range, the contents of nitrogen-containing compounds and chlorine-containing compounds contained in the oil-containing composition tend to be reduced.

[0082] Other processing conditions are those generally used in fluid catalytic cracking of petroleum. For example, the reactor pressure is about 0.1 kg / cm 2 G~3.0kg / cm 2 G, catalyst to EVOH resin mass ratio (catalyst / EVOH resin) approximately 4 to 8, catalyst regeneration tower temperature approximately 500°C to 800°C, catalyst regeneration tower pressure approximately 0.1 kg / cm 2 G~3.0kg / cm 2 It's G.

[0083] 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.

[0084] By these methods, a pyrolyzed product can be obtained.

[0085] [Distillation process] The obtained pyrolysate is preferably distilled to remove impurities such as water, tar, etc. That is, the present production method preferably includes a distillation step after the step of obtaining the pyrolysate.

[0086] 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 even more 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.

[0087] The obtained pyrolysate may be centrifuged or otherwise treated to remove impurities such as water and tar before being subjected to the next step of obtaining a hydrogenated pyrolysate.

[0088] [Step of obtaining hydrogenated pyrolysis product] The thermal decomposition products contain impurities such as oxygen-containing compounds that are generated by the degradation of high molecular weight components contained in EVOH resins, etc. These oxygen-containing compounds cause corrosion of equipment and inhibit decomposition during naphtha cracking treatment. Therefore, in the present production method, the pyrolysate is subjected to a hydrogenation reaction to produce a hydrogenated pyrolysate, thereby reducing the content of oxygen-containing compounds (oxygen atom weight) to a specific range or less. That is, the hydrogenation reaction not only induces an addition reaction to carbon-carbon double bonds, but also reduces ketones, aldehydes, and carboxylic acids, converting them to hydroxy groups and further promoting a reaction to replace the hydroxy groups with hydrogen atoms, thereby converting them into hydrocarbons. Then, the proportion of oxygen atoms contained in the oil-based composition can be reduced by separating the hydrocarbons from the oxygen-containing compounds. The process for obtaining the hydrothermal decomposition product will be described below.

[0089] As a method for hydrogenating the thermal decomposition product, for example, a method of reacting the thermal decomposition product with a hydrorefining catalyst in the presence of hydrogen can be mentioned.

[0090] The hydrorefining catalyst is not particularly limited, and examples thereof include known transition metal oxides used in catalytic hydrorefining of petroleum. Specific examples include known transition metal oxides such as molybdenum oxide, nickel oxide, and cobalt oxide. These are preferably supported on the surface of an appropriate fine particle carrier made of one or more solid acids selected from alumina, silica, silica-alumina, titania, and zeolite, and one or more solid bases selected from magnesia.

[0091] The average particle size of the hydrotreating catalyst is usually 50 μm to 50,000 μm, preferably 500 μm to 5,000 μm, and the specific surface area measured by the BET method is usually 0.1 m 2 / g~1000m 2 / g, preferably 10m 2 / g~300m 2 / g.

[0092] The hydrogenation reaction may be carried out by adding a hydrorefining catalyst, typically 5 g to 500 g, preferably 20 g to 200 g, calculated as transition metal oxide, per 1 kg of the thermal decomposition product, and pressurizing and heating the mixture under hydrogen.

[0093] The volume ratio of the hydrogen to the pyrolysate (hydrogen / pyrolysate) is usually 20-100.

[0094] The pressure during the hydrogenation reaction is usually 0.5 MPa to 15 MPa, and preferably 1 MPa to 10 MPa, and the temperature is usually 200°C to 600°C, and preferably 220°C to 450°C. The reaction time is usually 0.5 to 10 hours, preferably 1 to 3 hours.

[0095] The hydrogenation reaction can be carried out by a known reaction method, for example, a batch reaction method, a fixed bed method, a tubular reaction method, a fluidized bed method, a moving bed method, or the like.

[0096] This hydrogenation reaction replaces functional groups derived from oxygen atoms contained in the pyrolysate with hydrogen, and the resulting oxygen-containing functional groups, such as hydroxyl groups, volatilize as water or low-molecular-weight gases, thereby reducing the oxygen atom content to a specific percentage or less. Furthermore, the hydrogenation reaction can also reduce the nitrogen and chlorine atom contents.

[0097] The present oil-reducing composition can be used as a naphtha feedstock. Furthermore, naphtha containing the oil-reducing composition can be subjected to a conventionally known naphtha cracking process to obtain a recycled chemical feedstock.

[0098] The present oil-refining composition contains low amounts of nitrogen-containing compounds and chlorine-containing compounds, and is less likely to cause corrosion of equipment or inhibit decomposition 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-refining composition include unsaturated hydrocarbons such as ethylene, propylene, 1-butene, butadiene, isoprene, benzene, toluene, xylene, styrene, and other unsaturated hydrocarbons useful as petrochemical raw materials. Among these, ethylene and / or propylene are preferred because they can be used as raw materials for a wide range of products, more preferably ethylene or propylene, and most preferably ethylene.

[0099] The obtained recycled chemical raw material is preferably used as a monomer composition containing the recycled chemical raw material. The monomer composition essentially contains the recycled chemical raw materials. The monomer composition may also contain other components within the scope of the present invention. Examples of other components include monomers other than the recycled chemical raw materials and compounding agents described in the resin composition. Examples of the 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 the monomers obtained by reacting recycled chemical raw materials include ethylene vinyl acetate monomer.

[0100] The monomer composition may be polymerized to form a resin composition containing a polymer. As a method for polymerizing the monomer composition, a conventionally known polymerization method may be used. The polymer may be, for example, an ethylene-vinyl acetate copolymer, and the resulting ethylene-vinyl acetate copolymer may be saponified to obtain an EVOH resin.

[0101] 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.

[0102] 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 low content of nitrogen-containing compounds and chlorine-containing compounds, and therefore it is possible to stably obtain recycled chemical raw materials and subsequent polymers and molded articles. [Example]

[0103] 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.

[0104] Prior to the examples, the following resins were prepared. EVOH resin: Mitsubishi Chemical Corporation's SoarnoL DC3203RB: ethylene structural unit content 32 mol%, MFR (210°C, load 2160 g) 3.8 g / 10 min, saponification degree 99.9 mol% Linear low-density polyethylene: NOVATEC UF240 manufactured by Japan Polypropylene Corporation: MFR (190°C, load 2160g) 2.1g / 10min, density 0.920g / cm3 Acid-modified polyethylene: Plexar PX3236 manufactured by LyondellBasell: MFR (190°C, load 2160g) 2.0g / 10min, density 0.922g / cm 3

[0105] Example 1 A resin composition was prepared by blending the resins in a mass ratio of linear low-density polyethylene:acid-modified polyethylene:EVOH resin = 80:10:10. 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 360-400°C. The internal temperature was then maintained at 360-400°C, and the resin composition was pyrolyzed over 3-4 hours. The pyrolyzate was then naturally cooled to room temperature, yielding a pyrolyzate. The pyrolyzate was distilled (at atmospheric pressure, the temperature was raised to 150°C, and the pressure was reduced to 100 mmHg). This pyrolyzate was then hydrogenated with a hydrotreating catalyst ("HYAc-5E N-type" manufactured by N.E. Chemcat Corporation) in the presence of hydrogen at 240°C and 5 MPa for 100 minutes, yielding the oil-based composition of Example 1, which contained a hydrogenated pyrolyzate with a hydrogenation rate of 97% or higher.

[0106] <Comparative Example 1> An oil composition of Comparative Example 1 was obtained in the same manner as in Example 1, except that the hydrogenation reaction was not carried out.

[0107] The content ratios of oxygen atoms, nitrogen atoms, and chlorine atoms contained in the obtained oil compositions of Example 1 and Comparative Example 1 were measured using an elemental analyzer (manufactured by Emmental GmbH). The results are shown in Table 1 below.

[0108] [Table 1]

[0109] From the results in Table 1, the oil composition of Example 1, which is an oil composition containing a hydrogenated pyrolysis product of a resin composition containing an ethylene-vinyl alcohol copolymer and in which the proportion of oxygen atoms contained in the oil composition is 1% by mass or less based on the oil composition, had a content of oxygen atoms derived from oxygen-containing compounds of less than 0.1% by mass, a content of nitrogen atoms derived from nitrogen-containing compounds that are thought to cause corrosion of equipment and inhibition of decomposition during naphtha cracking treatment of less than 0.1% by mass, and a low content of chlorine atoms derived from chlorine-containing compounds of less than 1 ppm. On the other hand, the oil composition of Comparative Example 1, which was not subjected to a hydrogenation reaction, had an oxygen atom content of 2.0 mass %, a nitrogen atom content of 0.4 mass %, and a chlorine atom content of 1.4 ppm, which are high and are thought to cause corrosion of equipment and inhibition of decomposition during naphtha cracking treatment. [Industrial Applicability]

[0110] The present oil-based composition and the oil-based composition obtained by the present production method have low content of impurities such as nitrogen-containing compounds and chlorine-containing compounds, and are unlikely to cause corrosion of equipment or inhibition of decomposition during naphtha cracking treatment, making them suitable for chemical recycling.

Claims

1. An oil-based composition containing a hydrothermal decomposition product of a resin composition containing an ethylene-vinyl alcohol copolymer, wherein the proportion of oxygen atoms contained in the oil-based composition is 1 mass % or less based on the mass of the oil-based composition.

2. 2. The oil-forming composition according to claim 1, wherein the ratio of nitrogen atoms contained in said oil-forming composition is 0.3% by mass or less based on the mass of the oil-forming composition.

3. 3. The oil-based composition according to claim 1, wherein the proportion of chlorine atoms contained in said oil-based composition is 1 ppm or less based on the oil-based composition.

4. 3. The oil composition according to claim 1, wherein the hydrogenation rate of the hydrothermal decomposition product is 70% or more.

5. A method for producing an oil-based composition containing a hydrogenated pyrolysate of a resin composition containing an ethylene-vinyl alcohol copolymer, the method comprising the steps of: pyrolyzing a resin composition containing an ethylene-vinyl alcohol copolymer to obtain a pyrolysate; and hydrogenating the pyrolysate to obtain the hydrogenated pyrolysate.

6. The method for producing an oil-based composition according to claim 5, wherein the temperature of the thermal decomposition is 240°C to 800°C.

7. The method for producing an oil-formed composition according to claim 5, further comprising a distillation step after the step of obtaining the pyrolysate.

8. The method for producing an oil-formed composition according to claim 7, 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.

9. The method for producing an oil-based composition according to any one of claims 5 to 8, wherein the proportion of oxygen atoms contained in the oil-based composition is 1 mass % or less based on the mass of the oil-based composition.

10. The method for producing an oil-based composition according to any one of claims 5 to 8, wherein the proportion of chlorine atoms contained in the oil-based composition is 1 ppm or less based on the oil-based composition.

11. The method for producing an oil composition according to any one of claims 5 to 8, wherein the hydrogenation rate of the hydrothermal decomposition product is 70% or more.

12. A chemical recycling method using the method for producing an oil-based composition according to any one of claims 5 to 8.

13. 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 5 to 8 to naphtha cracking treatment to obtain recycled chemical raw materials.

14. 14. The method for producing renewable chemical raw materials according to claim 13, wherein the renewable chemical raw materials are ethylene and / or propylene.

15. 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 claim 13 to obtain a polymer.

16. 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 claim 15 to obtain a molded article.

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