Methods for decomposing organic materials

Abstract

This invention provides a method for decomposing organic materials that allows for the selective acquisition of desired products. [Solution] A method for decomposing an organic material, comprising step (A) of mixing and decomposing at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymer having at least both a butadiene skeleton and an isoprene skeleton, wherein the catalyst has the following general formula (a), (b), or (c): TIFF2026131524000017.tif62162 [X a and X b This is a method for decomposing organic materials represented by [ ], where is Cl, Br, or I, and L is an N-heterocyclic carbene (NHC) ligand.

Description

[Technical Field]

[0001] This invention relates to a method for decomposing organic materials. [Background technology]

[0002] Traditionally, rubber products, primarily made from cross-linked rubber such as vulcanized rubber, have been difficult to recycle. After their lifespan, they are often reused as fuel, particularly in cement factories. However, with the growing environmental concerns, there is a growing demand for the development of methods to reuse materials obtained by decomposing rubber products, rather than burning them as fuel.

[0003] There are various methods for decomposing cross-linked rubber. For example, techniques for thermally decomposing cross-linked rubber at high temperatures and techniques for desulfurizing and reducing the molecular weight of vulcanized rubber to obtain a liquid polymer are known. Furthermore, Patent Document 1 below discloses a method for decomposing polyisoprene-based rubber using microorganisms.

[0004] Furthermore, in the manufacturing process of rubber products, uncrosslinked rubber material is sometimes discarded as scrap, and there is a need to develop methods for reusing such uncrosslinked rubber. Moreover, in the manufacture of rubber compositions that serve as raw materials for rubber products, liquid polymers are sometimes used as softeners, and there is a need to develop methods for reusing such liquid polymers. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-247241 [Overview of the project] [Problems that the invention aims to solve]

[0006] As described above, there are various methods for decomposing crosslinked rubber. However, since the crosslinked rubber to be discarded contains rubber components having various skeletons such as a rubber component having a butadiene skeleton and a rubber component having an isoprene skeleton, usually, the decomposition products obtained by decomposing the crosslinked rubber are a mixture, and complex purification and separation are required for utilization as chemical products. Further, even in the case of uncrosslinked rubber and liquid polymers, when decomposed in the same manner as crosslinked rubber, a mixture is obtained as the decomposition product, and complex purification and separation are required for utilization as chemical products. Therefore, there is a need for a decomposition method capable of selectively obtaining a target product from organic materials such as crosslinked rubber, uncrosslinked rubber, and liquid polymers.

[0007] Therefore, an object of the present invention is to solve the above problems of the prior art and provide a method for decomposing organic materials capable of selectively obtaining a target product.

Means for Solving the Problems

[0008] The gist configuration of the method for decomposing organic materials of the present invention for solving the above problems is as follows.

[0009] [1] A method for decomposing an organic material, comprising a step (A) of mixing at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymers, which has at least both a butadiene skeleton and an isoprene skeleton, with a catalyst and decomposing, wherein the catalyst is represented by the following general formula (a), (b) or (c):

Chemical formula

[0010] [2] The method for decomposing an organic material according to [1], wherein the liquid polymer has a weight-average molecular weight of 10,000 or more. The method for decomposing organic materials described in [2] above makes it easy to further decompose the decomposition products in step (A) in the next step.

[0011] [3] The method for decomposing an organic material according to [1] or [2], further comprising the step (B) of separating and recovering a liquid polymer having a butadiene skeleton from the decomposition product obtained in the step (A) of mixing the organic material with a catalyst to decompose it. The method for decomposing organic materials described in [3] above can greatly contribute to promoting the reuse of organic materials.

[0012] [4] The method for decomposing an organic material according to [3], further comprising a step (C) of decomposing the residue after a step (B) of separating and recovering the liquid polymer having the butadiene skeleton. The method for decomposing organic materials described in [4] above makes it possible to selectively obtain the desired product (in particular, a liquid polymer having an isoprene skeleton).

[0013] [5] The method for decomposing an organic material according to [4], further comprising a step (D) of separating and recovering a liquid polymer having an isoprene skeleton from the decomposition product obtained in the step (C) of decomposing the residue. The method for decomposing organic materials described in [5] above can greatly contribute to promoting the reuse of organic materials.

[0014] [6] The method for decomposing an organic material according to [5], further comprising the step (E) of decomposing the liquid polymer having the isoprene skeleton to obtain an isoprene monomer. The method for decomposing organic materials described in [6] above can greatly contribute to promoting the reuse of organic materials.

[0015] [7] A method for decomposing an organic material according to any one of [3] to [6], further comprising the step (F) of decomposing the liquid polymer having the butadiene skeleton to obtain a butadiene monomer. The method for decomposing organic materials described in [7] above can greatly contribute to promoting the reuse of organic materials.

[0016] [8] A method for decomposing an organic material according to [3] or [7], further comprising the step (G) of decomposing the residue after the step (B) of separating and recovering the liquid polymer having the butadiene skeleton to obtain an isoprene monomer. The method for decomposing organic materials described in [8] above can greatly contribute to promoting the reuse of organic materials. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a method for decomposing organic materials that allows for the selective acquisition of desired products. [Brief explanation of the drawing]

[0018] [Figure 1] This is an explanatory diagram of a method for decomposing organic materials according to one embodiment of the present invention. [Modes for carrying out the invention]

[0019] The method for decomposing organic materials according to the present invention will be described in detail below, based on its embodiments.

[0020] [Definition] The compounds described herein may be derived in part or in whole from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires. They may also be derived from a mixture of two or more of fossil resources, biological resources, or recycled resources.

[0021] [Methods for decomposing organic materials] The organic material decomposition method of this embodiment includes a step (A) of mixing at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymer having at least both a butadiene skeleton and an isoprene skeleton with a catalyst and decomposing it. In the organic material decomposition method of this embodiment, the catalyst is the following general formula (a), (b), or (c): [ka] [In the formula, R a , R b , R c , R d , R e , R f and R g Each of these is independently an alkyl group, a cycloalkyl group, or an aryl group. X a and X b These are, independently, Cl, Br, or I. L is characterized by being an N-heterocyclic carbene (NHC) ligand (hereinafter, the catalyst used in step (A) may be abbreviated as "G1 catalyst").

[0022] Normally, when organic materials (crosslinked rubber, uncrosslinked rubber, liquid polymers) having both a butadiene skeleton and an isoprene skeleton are decomposed, a complex mixture is obtained consisting of decomposition products having a butadiene skeleton, decomposition products having an isoprene skeleton, decomposition products having both a butadiene skeleton and an isoprene skeleton, etc. In contrast, according to the organic material decomposition method of this embodiment, by mixing the organic material with the G1 catalyst and decomposing it, it is possible to selectively obtain decomposition products mainly having a butadiene skeleton (particularly liquid polymers having a butadiene skeleton). Therefore, the method for decomposing organic materials in this embodiment makes it possible to selectively obtain the desired product (in particular, a liquid polymer having a butadiene skeleton).

[0023] The method for decomposing organic materials according to this embodiment will be described in detail below with reference to the drawings. Figure 1 is an explanatory diagram of the method for decomposing organic materials according to one embodiment of the present invention.

[0024] <Process (A)> The method for decomposing organic materials according to this embodiment includes a step (A) of mixing at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymer having at least both a butadiene skeleton and an isoprene skeleton with a catalyst to decompose it.

[0025] -Organic materials (raw materials)- In step (A) above, at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymers having at least both a butadiene skeleton and an isoprene skeleton is used as a raw material. These organic materials may be one type or a mixture of two or more types.

[0026] --Cross-linked rubber and uncross-linked rubber-- The aforementioned crosslinked rubber and uncrosslinked rubber include diene rubber having a butadiene skeleton and / or an isoprene skeleton, and may further contain carbon black, sulfur, etc.

[0027] The crosslinked and uncrosslinked rubbers used for decomposition may be grouped according to the type of filler they contain (for example, the type of carbon black, the type of silica, the mixing ratio of carbon black and silica, etc.), and decomposition may be carried out separately for each group. When decomposition is carried out by group in this way, recycled carbon black, recycled silica, etc. with more uniform physical properties can be obtained, and when they are incorporated back into a rubber composition, a rubber composition with better performance can be obtained.

[0028] Furthermore, if the cross-linked rubber used for decomposition is derived from tires, it may be grouped beforehand by tire type (for example, passenger car tires, truck and bus tires, heavy off-road vehicle tires, aircraft tires, agricultural vehicle tires, etc.) and then decomposed separately for each group. Alternatively, it may be grouped beforehand by tire component (for example, tread rubber, sidewall rubber, bead rubber, steel cord coated rubber, organic fiber coated rubber, pad rubber, cushion rubber, etc.) and then decomposed separately for each group. In addition, it may be grouped by both tire type and tire component, and then decomposed separately for each group. When decomposition is performed by group in this way, recycled carbon black with more uniform physical properties can be obtained, resulting in a rubber composition with better performance when it is again incorporated into a rubber composition.

[0029] The form of the crosslinked rubber is not particularly limited and may be, for example, powdered rubber. This powdered rubber can be obtained by cutting and crushing used rubber products such as waste tires. The crushing process may include multiple steps such as a preliminary crushing process and a fine crushing process, and the particle size of the powdered rubber to be used may be adjusted by a classification process after the crushing process. The form of the uncrosslinked rubber is not particularly limited, and examples include scraps of unvulcanized rubber sheets discarded during the manufacturing process of rubber products.

[0030] The diene-based rubber is a rubber containing units derived from diene monomers (diene units), and may further contain units derived from copolymerizable comonomers. The units derived from the diene monomer enable crosslinking (vulcanization) of the diene rubber and allow it to exhibit rubber-like elongation and strength. In crosslinked rubber, the diene rubber usually exists in a crosslinked state, but some parts may not be crosslinked. Specific examples of diene monomers (diene compounds) include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. 1,3-butadiene forms a butadiene skeleton, and isoprene forms an isoprene skeleton. Crosslinked rubber and uncrosslinked rubber have at least both a butadiene skeleton and an isoprene skeleton, but they may also contain both diene rubber having a butadiene skeleton and diene rubber having an isoprene skeleton, or diene rubber having both a butadiene skeleton and an isoprene skeleton. On the other hand, examples of copolymerizable comonomers include aromatic vinyl compounds. Examples of the aromatic vinyl compound include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, and p-ethylstyrene.

[0031] Examples of the aforementioned diene rubber include isoprene-backed rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR). Here, isoprene-backed rubber is rubber whose main backbone is isoprene units, and specifically includes natural rubber (NR) and synthetic isoprene rubber (IR). On the other hand, styrene-butadiene rubber (SBR) and butadiene rubber (BR) are diene rubbers having a butadiene backbone. In one embodiment of the present invention, the crosslinked rubber and the uncrosslinked rubber include isoprene-backed rubber and styrene-butadiene rubber (SBR) and / or butadiene rubber (BR).

[0032] The content of the diene-based rubber in the crosslinked rubber and the uncrosslinked rubber is not particularly limited, but is preferably in the range of 10 to 100% by mass, and more preferably in the range of 30 to 100% by mass.

[0033] The crosslinked rubber and uncrosslinked rubber may further contain carbon black. The carbon black is not particularly limited, and examples of carbon black grades include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The organic material decomposition method of this embodiment allows for the decomposition of the diene-based rubber in the crosslinked or uncrosslinked rubber to be reduced in molecular weight, even when the organic material to be decomposed is crosslinked or uncrosslinked rubber. Therefore, even if the crosslinked or uncrosslinked rubber contains carbon black, the carbon black can be easily separated and recovered after decomposition by means of centrifugal separation, filtration, etc., and the recovered carbon black can be reused. The carbon black content in the crosslinked and uncrosslinked rubber is not particularly limited, and is, for example, in the range of 10 to 150 parts by mass, preferably in the range of 30 to 120 parts by mass, per 100 parts by mass of the diene-based rubber. Furthermore, the carbon black content in the crosslinked and uncrosslinked rubber is preferably 20% by mass or more, more preferably 30% by mass or more, preferably 40% by mass or less, and even more preferably 35% by mass or less. When the carbon black content in the crosslinked and uncrosslinked rubber is 20% by mass or more, the amount of carbon black that can be recovered increases.

[0034] The crosslinked rubber and uncrosslinked rubber may further contain sulfur. In the crosslinked rubber, sulfur usually exists in a crosslinked state of the diene rubber (as a bridge for the diene rubber), but some may be free. The organic material decomposition method of this embodiment can decompose the diene rubber in the crosslinked rubber or uncrosslinked rubber and reduce its molecular weight in the thermal decomposition, even when the organic material to be decomposed is crosslinked rubber or uncrosslinked rubber. Therefore, even if the crosslinked rubber or uncrosslinked rubber contains sulfur, the sulfur can be easily recovered after thermal decomposition by, for example, centrifugation or filtration, and the recovered sulfur can be reused. The sulfur content in the crosslinked rubber and uncrosslinked rubber is not particularly limited, and for example, it is in the range of 0.1 to 10 parts by mass per 100 parts by mass of the diene rubber, with a range of 1 to 5 parts by mass being preferred.

[0035] The crosslinked rubber and uncrosslinked rubber may also contain, in addition to the diene-based rubber, carbon black, and sulfur mentioned above, various components commonly used in the rubber industry, such as rubber components other than diene-based rubber, fillers other than carbon black (silica, calcium carbonate, etc.), silane coupling agents, antioxidants, softeners, processing aids, resins, surfactants, organic acids (stearic acid, etc.), zinc oxide (zinc oxide), vulcanization accelerators, crosslinking agents other than sulfur (peroxide, etc.), etc.

[0036] --Liquid Polymer-- The diene-based rubber may be solid at 25°C, or it may be liquid at 25°C after its molecular weight has been reduced. The liquid rubber may be a commercially available diene-based liquid polymer, or a diene-based liquid polymer obtained by desulfurizing and reducing the molecular weight of vulcanized rubber through desulfurization or the like. Such a liquid polymer must have at least both a butadiene skeleton and an isoprene skeleton, and may include both a diene-based liquid polymer having a butadiene skeleton and a diene-based liquid polymer having an isoprene skeleton, or it may include a diene-based liquid polymer having both a butadiene skeleton and an isoprene skeleton. In one embodiment of the present invention, the liquid polymer includes liquid polyisoprene and liquid styrene-butadiene copolymer and / or liquid polybutadiene. From the perspective of resource recycling, it is preferable to use a diene-based liquid polymer obtained from vulcanized rubber, considering the objectives of the present invention. There are no particular limitations on the desulfurization and low-molecular-weight method for the vulcanized rubber, and examples include heat, shear, solvent heat treatment, catalysts, radical generators such as sulfur and peroxides, and methods using supercritical conditions of carbon dioxide.

[0037] The weight-average molecular weight (Mw) of the liquid polymer is usually 500 or more, preferably 1,000 or more, more preferably 10,000 or more, and usually 300,000 or less, preferably 250,000 or less. If the weight-average molecular weight of the liquid polymer is less than 200, it may be volatile and difficult to handle from the viewpoint of ignition. Also, if the weight-average molecular weight exceeds 300,000, it is semi-solid and difficult to handle. On the other hand, liquid polymers with a weight-average molecular weight of 10,000 or more are easily decomposed in the next step after step (A) (for example, steps (C), (E), (F), and (G) described later). Therefore, in a method for decomposing organic materials using a liquid polymer with a weight-average molecular weight of 10,000 or more as a raw material, the decomposition product in step (A) can be easily decomposed in the next step.

[0038] The aforementioned diene-based liquid polymer derived from vulcanized rubber is preferably one in which an average of 30% or more of units derived from diene monomers (diene units) remain, and from the viewpoint of monomer yield, preferably 50% or more by mass, and more preferably 70% or more by mass. If the remaining percentage of diene units is less than 30% by mass, the yield of the liquid polymer with reduced molecular weight due to decomposition will be low.

[0039] Furthermore, the diene-based liquid polymer may contain carbon black, silica, zinc oxide, sulfur, vulcanization accelerators, antioxidants, and their decomposition products, but it is desirable that solid components be removed, especially from the viewpoint of ensuring fluidity.

[0040] -catalyst- In the above step (A), the following general formula (a), (b), or (c): [ka] A catalyst represented by the formula (a), (b), or (c) is used. By mixing an organic material with the catalyst represented by the general formula (a), (b), or (c) and decomposing it, a decomposition product mainly having a butadiene skeleton (in particular, a liquid polymer having a butadiene skeleton) can be selectively obtained.

[0041] In the above general formulas (a) and (b), R a , R b , R c and R d , and also R in the above general formula (a) e , R f and R g Each of these is independently an alkyl group, a cycloalkyl group, or an aryl group. Preferably, the alkyl group has 1 to 30 carbon atoms; preferably, the cycloalkyl group has 3 to 20 carbon atoms; and preferably, the aryl group has 6 to 24 carbon atoms.

[0042] In the above general formulas (a), (b), and (c), X a and X b These are, independently, Cl (chlorine), Br (bromine), or I (iodine). Among these, X a and X b Cl is preferred as the primary chlorine.

[0043] In the general formula (c) above, L is an N-heterocyclic carbene (NHC) ligand. Examples of N-heterocyclic carbene (NHC) ligands include imidazolidine ligands, imidazole ligands, pyridine ligands, etc. The term "pyridine" includes, for example, pyridine, picolines (α-, β-, and γ-picolines), lutidines (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5-lutidines), collidine (2,4,6-trimethylpyridine), trifluoromethylpyridine, phenylpyridine, 4-(dimethylamino)pyridine, chloropyridines, bromopyridines, nitropyridines, quinolines, etc. In the imidazolidine ligand, imidazole ligand, and pyridine ligand, the hydrogen atoms bonded to the carbon atoms or nitrogen atoms constituting the imidazolidine ring, imidazole ring, and pyridine ring are linear or branched alkyl groups having 1 to 30 carbon atoms, cycloalkyl groups having 3 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 24 carbon atoms, carboxylates having 1 to 20 carbon atoms, or alkoxy groups having 1 to 20 carbon atoms. They may be substituted with a C2-C20 alkenyloxy group, a C2-C20 alkynyloxy group, a C6-C20 aryloxy group, a C2-C20 alkoxycarbonyl group, a C1-C20 alkylthio group, a C6-C20 arylthio group, a C1-C20 alkylsulfonyl group, a C1-C20 alkylsulfonate, a C6-C20 arylsulfonate, or a C1-C20 alkylsulfinyl group. Examples of the NHC ligands include 1,3-dimethylimidazolidine-2-ylidene, 1,3-bis(2,6-diisopropylphenyl)imidazolidine-2-ylidene, 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene, 1,3-dimethylimidazole-2-ylidene, 1,3-dicyclohexylimidazole-2-ylidene, and 1,3-diisopropylimidazole-2-ylidene.

[0044] The catalyst represented by the above general formula (a) is shown in the following structural formula (a-1): [ka] A catalyst represented by the formula [wherein Cy represents a cyclohexyl group] is preferred. By mixing the catalyst represented by structural formula (a-1) with an organic material and decomposing it, a decomposition product mainly having a butadiene skeleton (particularly a liquid polymer having a butadiene skeleton) can be obtained more selectively.

[0045] The catalyst represented by the above general formula (b) is shown in structural formula (b-1): [ka] A catalyst represented by the formula [wherein Cy represents a cyclohexyl group] is preferred. By mixing the catalyst represented by structural formula (b-1) with an organic material and decomposing it, a decomposition product mainly having a butadiene skeleton (particularly a liquid polymer having a butadiene skeleton) can be obtained more selectively.

[0046] The catalyst represented by the above general formula (c) is shown in the following structural formula (c-1): [ka] A catalyst represented by the formula [wherein Mes represents a mesityl group (also called a "2,4,6-trimethylphenyl group")] is preferred. By mixing the catalyst represented by structural formula (c-1) with an organic material and decomposing it, a decomposition product mainly having a butadiene skeleton (in particular, a liquid polymer having a butadiene skeleton) can be obtained more selectively.

[0047] Among the catalysts mentioned above, catalysts represented by structural formula (a-1) and catalysts represented by structural formula (c-1) are particularly preferred from the viewpoint of improving the yield of decomposition products, as they are more reactive.

[0048] The amount of catalyst used (total amount used when multiple types of catalysts are used) represented by the above general formula (a), (b), or (c) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, per 100 parts by mass of the raw material organic material. If the amount of catalyst used is 0.1 parts by mass or more per 100 parts by mass of the organic material, the decomposition reaction of the organic material proceeds further, and if the amount of catalyst used is 10 parts by mass or less per 100 parts by mass of the organic material, it is preferable in terms of cost.

[0049] -Reaction conditions, etc- Step (A) is preferably carried out at a temperature of 20°C or higher and 200°C or lower. Carrying out step (A) at 20°C or higher improves the rate of the decomposition reaction of the organic raw materials, and carrying out step (A) at 200°C or lower suppresses the decomposition of the G1 catalyst (metathesis catalyst) and improves the retention rate (selectivity) of the butadiene skeleton in the decomposition product. From the viewpoint of improving the rate of the decomposition reaction of the organic materials, step (A) is more preferably 25°C or higher, and from the viewpoint of suppressing the decomposition of the G1 catalyst and improving the selectivity of the decomposition product that retains the butadiene skeleton, it is more preferably 100°C or lower.

[0050] Step (A) described above can be carried out at any pressure, including reduced pressure, atmospheric pressure, or increased pressure. For example, the reaction pressure is preferably 1 kPa to 10 MPa, more preferably 10 kPa to 1 MPa, and even more preferably 50 kPa to 500 kPa.

[0051] In the method for decomposing organic materials according to this embodiment, the above-mentioned G1 catalyst may be dissolved in a solvent, and the organic material may be immersed in the solvent before performing step (A). By allowing the G1 catalyst to act on the organic material in the solvent, the decomposition reaction of the organic material proceeds more easily. Here, any solvent that does not inhibit the decomposition reaction can be used as the solvent, for example, ethers, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons (aromatic solvents), etc. More specifically, tetrahydrofuran (THF), hexane, cyclohexane, pentane, cyclopentane, toluene, and xylene are preferred as solvents, and toluene and tetrahydrofuran are more preferred. When the solvent is selected from tetrahydrofuran, hexane, cyclohexane, pentane, cyclopentane, toluene, and xylene, the decomposition reaction of the organic material proceeds even more easily. The amount of solvent used is preferably 10 mL or more per gram of organic material, more preferably 50 mL or more, more preferably 500 mL or less, and more preferably 200 mL or less. If the amount of solvent used is 10 mL or more per gram of organic material, the decomposition reaction of the organic material proceeds further, and if the amount of solvent used is 500 mL or less per gram of organic material, it is preferable in terms of cost.

[0052] Step (A) may be carried out in the presence of a chain transfer agent (CTA). Examples of chain transfer agents include cis-1,4-diacetoxy-2-butene and cis-1,4-dibenzyloxy-2-butene. The amount of chain transfer agent used is preferably in the range of 1 to 100 mol per 1 mol of G1 catalyst.

[0053] <Process (B)> The method for decomposing an organic material in this embodiment preferably further includes a step (B) of separating and recovering a liquid polymer having a butadiene skeleton from the decomposition products obtained in step (A), which involves mixing the organic material with a catalyst (G1 catalyst) and decomposing it. In step (A), the organic material is reduced in molecular weight to produce a liquid polymer, and the decomposition products contain a greater abundance of liquid polymer having a butadiene skeleton than liquid polymer having an isoprene skeleton. In addition to the liquid polymer, the decomposition products also contain undecomposed solid organic material (crosslinked rubber, uncrosslinked rubber), undecomposed liquid organic material (liquid polymer), and other compounding agents (carbon black, etc.), but the liquid polymer with reduced molecular weight is easily recovered from the decomposition products. Therefore, it is possible to easily separate and recover the liquid polymer having a butadiene skeleton from the decomposition products obtained in step (A). Furthermore, the recovered liquid polymer having a butadiene skeleton can be used as is as a softening agent in rubber compositions, or it can be further decomposed (depolymerized) to be converted into a butadiene monomer. Therefore, the method for decomposing organic materials, including processes (A) and (B), can greatly contribute to promoting the reuse of organic materials.

[0054] The method for separating and recovering the liquid polymer having a butadiene skeleton from the decomposition product obtained in step (A) is not particularly limited. For example, if the raw material organic material is crosslinked rubber and / or uncrosslinked rubber, the liquid polymer having a butadiene skeleton can be easily separated and recovered by filtration. Also, if the raw material organic material is a liquid polymer, the liquid polymer having a butadiene skeleton, which is the product, has a much lower molecular weight than the raw material liquid polymer, so it can be easily separated and recovered by distillation or the like, or by precipitating the raw material liquid polymer using a poor solvent.

[0055] <Process (C)> The organic material decomposition method of this embodiment preferably further includes a step (C) of decomposing the residue after step (B) of separating and recovering the liquid polymer having a butadiene skeleton. The decomposition product obtained in step (A) contains a greater abundance of liquid polymer having a butadiene skeleton than liquid polymer having an isoprene skeleton. Of these, the liquid polymer having a butadiene skeleton can be easily recovered in step (B) as described above. On the other hand, the residue after step (B) is rich in organic material having an isoprene skeleton. Therefore, by decomposing the residue after step (B), it is possible to selectively obtain decomposition products mainly having an isoprene skeleton (particularly liquid polymer having an isoprene skeleton). Thus, the organic material decomposition method comprising steps (A), (B), and (C) makes it possible to selectively obtain the desired product (particularly liquid polymer having an isoprene skeleton).

[0056] The method for disassembling step (C) is not particularly limited, but for example, (i) A method of decomposing the residue after step (B) using a metathesis catalyst (first decomposition method), (ii) A method of thermally decomposing the residue after step (B) at a temperature of 150°C to 400°C (second decomposition method), (iii) A method for decomposing the residue after step (B) in a solvent (third decomposition method), (iv) A method of decomposing the residue after step (B) using a radical initiator (fourth decomposition method), (v) A method of radical decomposition of the residue after step (B) in the presence of oxygen (fifth decomposition method), These are some examples. Compared to conventional high-temperature thermal decomposition of cross-linked rubber, these first, second, third, fourth, and fifth decomposition methods are performed at low temperatures, thus suppressing gasification and aromatization of decomposition products, and also allowing for a higher retention rate of the isoprene skeleton in the decomposition products compared to normal high-temperature thermal decomposition. The first, second, third, fourth, and fifth decomposition methods will be described in detail below.

[0057] -First decomposition method (metathesis)- In the first decomposition method described above, the residue after step (B) is decomposed using a metathesis catalyst. Here, the metathesis catalyst is one of the following general formulas (1), (2), or (3): [ka] A catalyst represented by the formula (1), (2), or (3) is preferred. Catalysts of general formula (1), (2), or (3) are excellent at promoting metathesis decomposition and can easily (under mild conditions) and rapidly decompose the residue after step (B).

[0058] In the above general formulas (1), (2), and (3), M is ruthenium (Ru), titanium (Ti), molybdenum (Mo), or tungsten (W). Among these, ruthenium is preferred as M from the viewpoint of promoting the decomposition reaction of the residue after step (B).

[0059] In the above general formulas (1) and (2), X 1 and X 2 Each of these independently represents a ligand, preferably an anionic ligand. 1 and X 2Examples include hydrogen, halogens, pseudohalogens, linear or branched C1-C30 alkyl groups, C6-C24 aryl groups, C1-C20 alkoxy groups, C6-C24 aryloxy groups, C3-C20 alkyl diketonates, C6-C24 aryl diketonates, C1-C20 carboxylates, C1-C20 alkyl sulfonates, C6-C24 aryl sulfonates, C1-C20 alkyl thiol groups, C6-C24 aryl thiol groups, C1-C20 alkyl sulfonyl groups, or C1-C20 alkyl sulfinyl groups. The above X 1 and X 2 This group may be substituted with one or more additional groups, such as halogens (preferably fluorine), C1-C10 alkyl groups, C1-C10 alkoxy groups, or C6-C24 aryl groups, where these groups may also be further substituted with one or more substituents selected from the group consisting of halogens (preferably fluorine), C1-C5 alkyl groups, C1-C5 alkoxy groups, and phenyl groups. In a preferred embodiment, X 1 and X 2 These are identical or different, and each is a halogen (especially fluorine, chlorine, bromine, or iodine), a benzoate, a carboxylate having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, a phenoxy group, an alkoxy group having 1 to 5 carbon atoms, an alkylthiol group having 1 to 5 carbon atoms, an arylthiol group having 6 to 24 carbon atoms, an aryl group having 6 to 24 carbon atoms, or an alkylsulfonate having 1 to 5 carbon atoms. In a particularly preferred embodiment, X 1 and X 2 These are identical, and each is a halogen (especially chlorine), CF3COO, CH3COO, CFH2COO, (CH3)3CO, (CF3)2(CH3)CO, (CF3)(CH3)2CO, PhO (phenoxy), MeO (methoxy), EtO (ethoxy), tosylate (p-CH3-C6H4-SO3), mesylate (2,4,6-trimethylphenyl), or CF3SO3 (trifluoromethanesulfonate).

[0060] In the above general formulas (1), (2), and (3), L 1 , L 2 and L 3 Each of these independently represents a ligand, and is preferably a neutral (uncharged) electron donor (also called an "electron-donating neutral ligand"). 1 , L 2 and L 3 These can be, for example, phosphines, sulfonated phosphines, phosphates, phosphinosides, phosphonitrates, arsines, stivins, ethers, amines, amides, aryloxys, sulfonates, sulfoxides, carboxyls, nitrosyls, pyridines, thioethers, or imidazolidine ligands, independently of each other. 1 , L 2 and L 3 These are, independently of each other, arylphosphine ligands having 6 to 24 carbon atoms, alkylphosphines having 1 to 10 carbon atoms or cycloalkylphosphine ligands having 3 to 20 carbon atoms, sulfonated arylphosphines having 6 to 24 carbon atoms or sulfonated alkylphosphine ligands having 1 to 10 carbon atoms, arylphosphinates having 6 to 24 carbon atoms or alkylphosphinate ligands having 1 to 10 carbon atoms, arylphosphonites having 6 to 24 carbon atoms or alkylphosphonites having 1 to 10 carbon atoms, arylarsines having 6 to 24 carbon atoms or Preferably, the ligand is a C1-C10 alkylarsine ligand, a C6-C24 arylamine or C1-C10 alkylamine ligand, a pyridine ligand, a C6-C24 aryl sulfoxide or C1-C10 alkyl sulfoxide ligand, a C6-C24 aryl ether or C1-C10 alkyl ether ligand, or a C6-C24 arylamide or C1-C10 alkylamide ligand, each of which may be substituted with a phenyl group, and the phenyl group may be further optionally substituted with a halogen, a C1-C5 alkyl group or a C1-C5 alkoxy group. The term "phosphine" includes, for example, PPh3, P(p-Tol)3, P(o-Tol)3, PPh(CH3)2, P(CF3)3, P(p-FC6H4)3, P(p-CF3C6H4)3, P(C6H4-SO3Na)3, P(CH2C6H4-SO3Na)3, P(isopropyl)3, P(CHCH3(CH2CH3))3, P(cyclopentyl)3, P(cyclohexyl)3, P(neopentyl)3, and P(neophenyl)3. The term "phosphinite ester" includes, for example, triphenyl phosphinite, tricyclohexyl phosphinite, triisopropyl phosphinite, and methyldiphenyl phosphinite. The term "phosphite ester" includes, for example, triphenyl phosphite, tricyclohexyl phosphite, tri-tert-butyl phosphite, triisopropyl phosphite, and methyldiphenyl phosphite. The term "stibin" includes, for example, triphenylstibin, tricyclohexylstibin, and trimethylstibin. The term "aryloxy" includes, for example, 2-tert-butyl-4,5-dimethylphenyloxy. The term "sulfonate" includes, for example, trifluoromethanesulfonate, tosylate, and mesylate. The term "sulfoxide" includes, for example, (CH3)2S(=O) and (C6H5)2S=O. The term "thioether" includes, for example, CH3SCH3, C6H5SCH3, CH3OCH2CH2SCH3, and tetrahydrothiophene. The term "pyridine" includes, for example, pyridine, picolines (α-, β-, and γ-picolines), lutidines (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5-lutidines), collidine (2,4,6-trimethylpyridine), trifluoromethylpyridine, phenylpyridine, 4-(dimethylamino)pyridine, chloropyridines, bromopyridines, nitropyridines, quinoline, pyrimidine, pyrrole, imidazole, and phenylimidazole. In the imidazolidine ligand, the hydrogen atoms bonded to the carbon atoms or nitrogen atoms constituting the imidazolidine ring may be substituted with linear or branched C1-C30 alkyl groups, C3-C20 cycloalkyl groups, C2-C20 alkenyl groups, C2-C20 alkynyl groups, C6-C24 aryl groups, C1-C20 carboxylates, C1-C20 alkoxy groups, C2-C20 alkenyloxy groups, C2-C20 alkynyloxy groups, C6-C20 aryloxy groups, C2-C20 alkoxycarbonyl groups, C1-C20 alkylthio groups, C6-C20 arylthio groups, C1-C20 alkylsulfonyl groups, C1-C20 alkylsulfonates, C6-C20 arylsulfonates, or C1-C20 alkylsulfinyl groups.

[0061] In the above general formulas (1), (2), and (3), R 1 , R 2 and R 3 Each of these independently represents hydrogen, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a carboxylate group, an alkoxy group, an alkenyloxy group, an alkynyloxy group, an aryloxy group, an alkoxycarbonyl group, an alkylamino group, an alkylthio group, an arylthio group, an alkylsulfonyl group, or an alkylsulfinyl group, where these groups may be substituted with one or more alkyl groups, halogens, alkoxy groups, aryl groups, or heteroaryl groups. Furthermore, preferred alkyl groups are those having 1 to 30 carbon atoms, preferred cycloalkyl groups are those having 3 to 20 carbon atoms, preferred alkenyl groups are those having 2 to 20 carbon atoms, preferred alkynyl groups are those having 2 to 20 carbon atoms, preferred aryl groups are those having 6 to 24 carbon atoms, preferred aralkyl groups are those having 7 to 24 carbon atoms, preferred carboxylate groups are those having 1 to 20 carbon atoms, preferred alkoxy groups are those having 1 to 20 carbon atoms, and preferred alkenyloxy groups are those having 2 to 20 carbon atoms. As the alkynyloxy group, an alkynyloxy group having 2 to 20 carbon atoms is preferred; as the aryloxy group, an aryloxy group having 6 to 24 carbon atoms is preferred; as the alkoxycarbonyl group, an alkoxycarbonyl group having 2 to 20 carbon atoms is preferred; as the alkylamino group, an alkylamino group having 1 to 30 carbon atoms is preferred; as the alkylthio group, an alkylthio group having 1 to 30 carbon atoms is preferred; as the arylthio group, an arylthio group having 6 to 24 carbon atoms is preferred; as the alkylsulfonyl group, an alkylsulfonyl group having 1 to 20 carbon atoms is preferred. In one embodiment, R 1 and R 2 One of the groups is hydrogen, and the other is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 24 carbon atoms, an aralkyl group having 7 to 24 carbon atoms, a carboxylate group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkenyloxy group having 2 to 20 carbon atoms, an alkynyloxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 24 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, an alkylthio group having 1 to 30 carbon atoms, an arylthio group having 6 to 24 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, or an alkylsulfinyl group having 1 to 20 carbon atoms, and each of these groups may be substituted with one or more alkyl groups, halogens, alkoxy groups, aryl groups, or heteroaryl groups.

[0062] In the above general formulas (1), (2), and (3), L 1 and L 2 These may be joined together to form a ring. 1 and L 2 The ring formed by the bonding of these elements may be aliphatic or aromatic, and may be optionally substituted to contain one or more heteroatoms. Examples of heteroatoms include oxygen, sulfur, nitrogen, and phosphorus.

[0063] In the above general formulas (1), (2), and (3), R 1 and R 2 These elements may be joined together to form a ring. 1 and R 2 However, these R 1 and R 2 The ring formed by the bonded common carbon atom may be aliphatic or aromatic, and may be optionally substituted to contain one or more heteroatoms.

[0064] In the above general formulas (1), (2), and (3), L 1 and R 1 These may be joined together to form a ring. 1 and R 1 The ring formed by the bonding of these elements may be aliphatic or aromatic, and may be optionally substituted to contain one or more heteroatoms. Examples of heteroatoms include oxygen, sulfur, nitrogen, and phosphorus.

[0065] The catalyst represented by the above general formula (1) is shown in the following structural formulas (1-1) to (1-3): [ka] A catalyst represented by either of the following formulas is preferred: [wherein Cy represents a cyclohexyl group and Mes represents a mesityl group (also known as a "2,4,6-trimethylphenyl group")]. The catalyst represented by structural formula (1-1) is called the Grubbs first-generation catalyst, the catalyst represented by structural formula (1-2) is called the Grubbs second-generation catalyst, and the catalyst represented by structural formula (1-3) is called the Grubbs-Hovbaida second-generation catalyst. Using a catalyst represented by any of structural formulas (1-1) to (1-3) allows the decomposition reaction (metathesis) of the residue after step (B) to proceed more rapidly.

[0066] The catalyst represented by the above general formula (2) is shown in structural formula (2-1): [ka] A catalyst represented by structural formula (2-1) is preferred. The catalyst of structural formula (2-1) is called the Grubbs third-generation catalyst. When the catalyst represented by structural formula (2-1) is used, the decomposition reaction (metathesis) of the residue after step (B) proceeds more rapidly.

[0067] The catalyst represented by the above general formula (3) is shown in structural formula (3-1): [ka] Examples of catalysts include those represented by [formula].

[0068] The amount of metathesis catalyst used is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and more preferably 10 parts by mass or less, and more preferably 8 parts by mass or less, per 100 parts by mass of the residue after step (B). If the amount of metathesis catalyst used is 0.1 parts by mass or more per 100 parts by mass of the residue after step (B), the decomposition reaction of the residue after step (B) will proceed further, and if the amount of metathesis catalyst used is 10 parts by mass or less per 100 parts by mass of the residue after step (B), it is preferable in terms of cost.

[0069] The decomposition by the metathesis catalyst (hereinafter sometimes simply referred to as "metathesis decomposition") is preferably carried out at a temperature of 20°C to 200°C. Carrying out the metathesis decomposition at a temperature of 20°C or higher improves the rate of the decomposition reaction of the residue after step (B), and carrying out the metathesis decomposition at a temperature of 200°C or lower suppresses the decomposition of the metathesis catalyst and improves the retention rate (selectivity) of the isoprene skeleton in the decomposition product. From the viewpoint of improving the rate of the decomposition reaction of the residue after step (B), the metathesis decomposition is more preferably carried out at a temperature of 25°C or higher, and from the viewpoint of suppressing the decomposition of the metathesis catalyst and improving the selectivity of the decomposition product that maintains the isoprene skeleton, it is more preferably carried out at a temperature of 100°C or lower.

[0070] The metathesis decomposition described above can be carried out at any pressure, including under reduced pressure, atmospheric pressure, or pressurized pressure. For example, the reaction pressure is preferably 1 kPa to 10 MPa, more preferably 10 kPa to 1 MPa, and even more preferably 50 kPa to 500 kPa.

[0071] In the metathesis decomposition described above, the metathesis catalyst may be dissolved in the solvent, or the residue after step (B) may be immersed in the solvent. By reacting the residue after step (B) with the metathesis catalyst in the solvent, the decomposition reaction of the residue after step (B) proceeds more easily. Here, any solvent that does not inhibit the decomposition reaction can be used as the solvent, for example, ethers, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons (aromatic solvents), etc. More specifically, tetrahydrofuran (THF), hexane, cyclohexane, pentane, cyclopentane, toluene, and xylene are preferred as solvents, and toluene and tetrahydrofuran are more preferred. When the solvent is selected from tetrahydrofuran, hexane, cyclohexane, pentane, cyclopentane, toluene, and xylene, the decomposition reaction of the residue after step (B) proceeds more easily. The amount of solvent used is preferably 10 mL or more, more preferably 50 mL or more, and more preferably 500 mL or less, and even more preferably 200 mL or less, per gram of residue after step (B). If the amount of solvent used is 10 mL or more per gram of residue after step (B), the decomposition reaction of the residue after step (B) will proceed further, and if the amount of solvent used is 500 mL or less per gram of residue after step (B), it is preferable in terms of cost.

[0072] The metathesis degradation may be carried out in the presence of a chain transfer agent (CTA). Examples of chain transfer agents include cis-1,4-diacetoxy-2-butene and cis-1,4-dibenzyloxy-2-butene. The amount of chain transfer agent used is preferably in the range of 1 to 100 mol per 1 mol of the catalyst.

[0073] -Second decomposition method (low-temperature thermal decomposition)- In the second decomposition method described above, the residue after step (B) is thermally decomposed at a temperature of 150°C to 400°C. Performing thermal decomposition at a temperature of 150°C or higher improves the rate of the decomposition reaction of the residue after step (B), and performing thermal decomposition at a temperature of 400°C or lower suppresses gasification and aromatization of the decomposition products, and also improves the retention rate (selectivity) of the isoprene skeleton in the decomposition products. From the viewpoint of improving the rate of the decomposition reaction of the residue after step (B), the thermal decomposition temperature is preferably 175°C or higher, and more preferably 190°C or higher. Furthermore, from the viewpoint of improving the selectivity of the decomposition products that maintain the isoprene skeleton, the temperature is preferably 350°C or lower, and more preferably 300°C or lower.

[0074] The second decomposition method described above is preferably carried out under an inert gas atmosphere. By carrying out thermal decomposition under an inert gas atmosphere, oxidation and reduction of the decomposition products can be suppressed, and in particular, hydrogenation of double bonds in the decomposition products can be suppressed. Oxidation of recycled carbon black can also be suppressed. Examples of inert gases include nitrogen, carbon dioxide, argon, and helium. To carry out the thermal decomposition under an inert gas atmosphere, for example, when using a batch reactor, the atmosphere charged into the reactor should be an inert gas, and when using a flow-through reactor, the atmosphere circulating through the reactor should be an inert gas. Although hydrogen may be generated during thermal decomposition, the generated hydrogen is not taken into consideration when determining the atmosphere for thermal decomposition.

[0075] The aforementioned thermal decomposition can be carried out at any pressure, including under reduced pressure, atmospheric pressure, or under pressure, but it is preferable to carry it out under reduced pressure or atmospheric pressure. As an example, the reaction pressure for thermal decomposition is preferably 1000 kPa to 65 kPa. By carrying out thermal decomposition under reduced pressure or atmospheric pressure, polymerization (repolymerization) of the decomposition products can be suppressed.

[0076] The reaction time for the thermal decomposition is not particularly limited. For example, the reaction time for thermal decomposition is preferably 1 to 180 minutes, more preferably 3 to 60 minutes, and even more preferably 5 to 30 minutes.

[0077] The aforementioned thermal decomposition may or may not be performed with a catalyst, but it is preferable not to use a catalyst. Not using a catalyst in the thermal decomposition can reduce costs. If a catalyst is used, any catalyst that promotes the decomposition reaction of organic materials can be used.

[0078] -Third decomposition method (solvent decomposition)- In the third decomposition method described above, the residue after step (B) is decomposed in a solvent. When the decomposition of the residue after step (B) is carried out in a solvent, the residue after step (B) swells due to the solvent. By decomposing the residue after step (B) under solvent swelling, gasification and aromatization of the decomposition products can be suppressed, and the retention rate of the isoprene skeleton in the decomposition products can be increased compared to conventional high-temperature thermal decomposition.

[0079] Various solvents that have the effect of swelling the residue after step (B) can be used as the solvent, for example, aromatic solvents, aliphatic solvents, alicyclic solvents, ester solvents, ethers, etc. Aromatic solvents include benzene, toluene, xylene, etc., aliphatic solvents include pentane, hexane, heptane, etc., alicyclic solvents include cyclopentane, cyclohexane, etc., ester solvents include ethyl acetate, propyl acetate, butyl acetate, etc., and ethers include tetrahydrofuran (THF), etc. Among these, at least one selected from the group consisting of toluene, xylene, and cyclohexane is preferred as the solvent, and toluene is particularly preferred. Using toluene, xylene, or cyclohexane as the solvent can further increase the retention rate of the isoprene skeleton in the decomposition product.

[0080] The amount of solvent used is preferably 1 mL or more, more preferably 5 mL or more, and more preferably 500 mL or less, and more preferably 200 mL or less, per gram of residue after step (B). If the amount of solvent used is 10 mL or more per gram of residue after step (B), the decomposition reaction of the residue after step (B) will proceed further, and if the amount of solvent used is 500 mL or less per gram of residue after step (B), it is preferable in terms of cost.

[0081] The decomposition temperature in the solvent is preferably 150 to 300°C. Performing the decomposition in the solvent at 150°C or higher improves the rate of the decomposition reaction of the residue after step (B), and performing the decomposition in the solvent at 300°C or lower suppresses gasification and aromatization of the decomposition products, improving the retention rate (selectivity) of the isoprene skeleton in the decomposition products. Furthermore, for example, if the residue after step (B) contains carbon black, it can be recovered as high-grade carbon black and reused. From the viewpoint of improving the rate of the decomposition reaction of the residue after step (B), the decomposition temperature in the solvent is preferably 180°C or higher, and more preferably 200°C or higher. Furthermore, from the viewpoint of improving the selectivity of the decomposition products that maintain the isoprene skeleton, it is preferably 260°C or lower, and more preferably 240°C or lower.

[0082] The decomposition time in the solvent is not particularly limited. For example, the decomposition time in the solvent is preferably 1 to 48 hours, and more preferably 3 to 18 hours. Performing the decomposition in the solvent for 1 hour or more improves the decomposition rate of the residue after step (B). On the other hand, if the reaction time is too long, the isoprene skeleton (double bond, etc.) in the decomposition product may be decomposed, or the decomposition product may be gasified or aromatized. However, by performing the decomposition in the solvent for 48 hours or less, the decomposition of the isoprene skeleton and the gasification and aromatization of the decomposition product can be suppressed, and the retention rate (selectivity) of the isoprene skeleton in the decomposition product is improved.

[0083] The decomposition in the solvent is preferably carried out under an inert gas atmosphere. By carrying out the decomposition in the solvent under an inert gas atmosphere, the number of active species (oxygen, hydrogen, etc.) dissolved in the solvent can be reduced, thereby suppressing oxidation and reduction of the decomposition products, and in particular, the hydrogenation of double bonds in the decomposition products can be suppressed. Furthermore, if the residue after step (B) contains carbon black, the oxidation of the carbon black can also be suppressed. Examples of inert gases include nitrogen, carbon dioxide, argon, and helium.

[0084] To carry out the decomposition in the aforementioned solvent under an inert gas atmosphere, for example, when using a batch reactor, the atmosphere supplied to the reactor should be an inert gas, and when using a flow-through reactor, the atmosphere circulating through the reactor should be an inert gas. Although hydrogen may be generated during the decomposition in the solvent, the generated hydrogen is not taken into consideration when determining the atmosphere for the decomposition in the solvent.

[0085] The decomposition in the aforementioned solvent can be carried out at any pressure, including under reduced pressure, atmospheric pressure, or under pressure. For example, the reaction pressure is preferably 1 kPa to 10 MPa, more preferably 10 kPa to 5 MPa, and even more preferably 50 kPa to 2 MPa.

[0086] A catalyst may or may not be used for the decomposition in the solvent, but it is preferable not to use a catalyst. By not using a catalyst for the decomposition in the solvent, costs can be reduced. If a catalyst is used, any catalyst that promotes the decomposition reaction of the residue after step (B) can be used.

[0087] -Fourth decomposition method (radical decomposition using a radical initiator)- In the fourth decomposition method described above, a radical initiator is applied to the residue after step (B) in an atmosphere containing oxygen gas. It is believed that the radical initiator acts mainly on the sulfur-based crosslinking sites, breaking the crosslink bonds. Therefore, in the case of diene rubber, it is considered that its main chain skeleton is basically maintained even after the decomposition reaction.

[0088] Various conventionally known radical initiators can be used, but from the viewpoint of reaction efficiency, peroxides and azo compounds are preferred, and peroxides are more preferably used. Examples of peroxides include acyl peroxide, percarboxylic acid, dialkyl peroxide, and alkyl hydroperoxide. Of these, acyl peroxide and percarboxylic acid are preferred from the viewpoint of reaction rate, and acyl peroxide is more preferred. Specific examples of acyl peroxides include benzoyl peroxide, toluyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, methoxybenzoyl peroxide, phthaloyl peroxide, acetyl peroxide, propanoyl peroxide, caprylyl peroxide, decanoyl peroxide, lauroyl peroxide, myristoyl peroxide, and stearoyl peroxide. Among acyl peroxides, benzoyl peroxide, lauroyl peroxide, and acetyl peroxide are preferred from the viewpoint of reaction rate, cost, and availability. From the viewpoint of reaction rate and peroxide stability, lauroyl peroxide is preferred over benzoyl peroxide. Examples of percarboxylic acids include perbenzoic acid, chloroperbenzoic acid, peracetic acid, and perpropionic acid. Furthermore, examples of dialkyl peroxides include di-tert-butyl peroxide, dicumyl peroxide, and tert-butylcumyl peroxide, while examples of alkyl hydroperoxides include tert-butyl hydroperoxide and cumene hydroperoxide. On the other hand, examples of azo compounds include azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrate, and methyl azobisisobutyrate. These radical initiators may also be in hydrated form, from the viewpoint of safety and availability. By using a suitable initiator, the residue after step (B) can be efficiently decomposed under mild conditions.

[0089] The amount of radical initiator used is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, more preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the residue after step (B). If the amount of radical initiator used is 0.1 parts by mass or more per 100 parts by mass of the residue after step (B), the decomposition reaction of the residue after step (B) proceeds more rapidly, and if the amount of radical initiator used is 30 parts by mass or less per 100 parts by mass of the residue after step (B), it is preferable in terms of cost.

[0090] The fourth decomposition method is carried out in an atmosphere containing oxygen gas. The oxygen gas concentration (volume %) in the reaction atmosphere is usually 1 to 100%, preferably 1 to 80%, and more preferably 5 to 50%, including about 20%, which is the oxygen concentration in the atmosphere. If the oxygen gas concentration is not 100%, an inert gas such as nitrogen gas can be used as the remaining gas component. In general, the decomposition reaction of the fourth decomposition method is more advantageous with higher oxygen concentrations, but undesirable side reactions are also more likely to occur. Therefore, when the oxygen concentration is high, it is preferable to appropriately control the reaction time, reaction temperature, etc. On the other hand, using air with an oxygen concentration of approximately 20% eliminates the need to separately prepare oxygen gas, which is advantageous in terms of equipment and economy. In reactions under an air atmosphere, if the amount of residue after step (B) is small, the reaction will proceed even in a sealed container with a sufficiently large internal volume. In that case, the internal volume of the reaction container is generally 50 volumes or more, and more preferably 100 volumes or more, per 1 volume of residue after step (B). When the fourth decomposition method is carried out in a closed system, if the amount of residue after step (B) is large, a reaction vessel with a large internal volume is required, which is not desirable from an equipment standpoint. Therefore, from an equipment standpoint, it is preferable to carry out the reaction in an open system that allows the flow of air, etc. To make the reaction system an open system, methods such as opening a part of the reaction vessel, installing a membrane that allows the flow of air, etc., or allowing air, etc. to overflow can be considered. Another advantageous method is to carry out the reaction while continuously or intermittently blowing air, etc., into the solution. In this case, there are no particular restrictions on the blowing rate, but it is usually 1 to 1000 mL / min, preferably 2 to 500 mL / min, and more preferably 3 to 200 mL / min per gram of residue after step (B).

[0091] In the fourth decomposition method described above, the radical initiator may be dissolved in a solvent and used, or the residue after step (B) may be immersed in a solvent to perform decomposition. By reacting the residue after step (B) with the radical initiator in a solvent, the decomposition of the residue after step (B) is facilitated. Here, any solvent that does not inhibit the decomposition reaction can be used as the solvent, for example, aromatic hydrocarbons (aromatic solvents), chlorinated hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, ethers, etc. Specifically, aromatic hydrocarbons include toluene, xylene, ethylbenzene, trimethylbenzene, propylbenzene, etc., chlorinated hydrocarbons include chloroform, dichloromethane, dichloroethane, trichloroethane, tetrachloroethane, tetrachloroethene, chlorobenzene, dichlorobenzene, etc., aliphatic hydrocarbons include pentane, hexane, octane, etc., alicyclic hydrocarbons include cyclopentane, cyclohexane, cyclooctane, etc., and ethers include tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, dioxane, etc. Among these, aromatic hydrocarbons and chlorinated hydrocarbons are preferred from the viewpoint of reaction rate, availability, etc. Specific examples include toluene, xylene, ethylbenzene, chloroform, chlorobenzene, and dichlorobenzene. Among aromatic hydrocarbons, ethylbenzene is preferred over toluene from the viewpoint of reaction rate. The solvent suitable for the decomposition reaction also depends on the type of residue after step (B). For example, if the residue after step (B) is NR, IR, or BR type rubber, aromatic hydrocarbons and chlorinated hydrocarbons are preferred from the viewpoint of reaction rate and product solubility, and specific examples of these include toluene, ethylbenzene, chloroform, and chlorobenzene. On the other hand, in the case of SBR type rubber, chlorinated hydrocarbons are more preferred from the viewpoint of reaction rate, and specific examples of these include chloroform and chlorobenzene. By using a preferred solvent, the decomposition of the residue after step (B) proceeds more easily, and the decomposition product (liquid polymer) can be produced more efficiently.

[0092] The amount of solvent used is preferably 2 mL or more, more preferably 10 mL or more, and more preferably 100 mL or less, and even more preferably 50 mL or less, per gram of residue after step (B). If the amount of solvent used is 2 mL per gram of residue after step (B), the decomposition reaction of the residue after step (B) is promoted, and if the amount of solvent used is 50 mL or less per gram of residue after step (B), it is preferable in terms of cost.

[0093] The fourth decomposition method is preferably carried out at a temperature between 0°C and 200°C. Carrying out the fourth decomposition method at a temperature above 0°C improves the rate of the decomposition reaction of the residue after step (B), and carrying out the fourth decomposition method at a temperature below 200°C improves the retention rate (selectivity) of the isoprene skeleton in the decomposition product. From the viewpoint of improving the rate of the decomposition reaction of the residue after step (B), the fourth decomposition method is more preferably at a temperature above 10°C, and from the viewpoint of improving the selectivity of the decomposition product that maintains the isoprene skeleton, it is more preferably at a temperature below 150°C. Furthermore, when a peroxide-based radical initiator is used, the reaction proceeds at low temperatures below 60°C due to the high decomposition efficiency. Another advantage of using a peroxide-based radical initiator is that the reaction proceeds smoothly even at room temperature (20-30°C), eliminating the need for special equipment for heating or cooling.

[0094] The fourth decomposition method described above can be carried out at any pressure, under reduced pressure, at atmospheric pressure, or under increased pressure. Specifically, the reaction pressure is preferably 1 kPa to 10 MPa, more preferably 10 kPa to 1 MPa, and even more preferably 50 kPa to 500 kPa.

[0095] In the fourth decomposition method described above, it is important to efficiently stir the residue after the raw material process (B), the radical initiator, and the solvent. Various conventionally known stirring methods can be used, such as using a magnetic stirrer, a mechanical stirrer, or a shaker. Furthermore, ultrasonic irradiation, microwave irradiation, light irradiation, etc., may be used in combination to accelerate the reaction. These can also be used in combination.

[0096] -Fifth decomposition method (radical decomposition under oxygen)- In the fifth decomposition method, the residue after step (B) is radically decomposed in an atmosphere containing oxygen gas. In the fifth decomposition method, it is thought that the reaction mainly acts on the CH bonds of the allyl moiety of the organic material (diene rubber) having an isoprene skeleton, thereby cleaving the bonds. Therefore, in the fifth decomposition method, it is thought that by appropriately adjusting the amount of oxygen gas, a decomposition product (particularly a liquid polymer having an isoprene skeleton) with a controlled molecular weight and mainly having an isoprene skeleton can be obtained.

[0097] The oxygen gas concentration (volume %) in the reaction atmosphere containing the oxygen gas is usually 1 to 40%, preferably 1 to 30%, and more preferably 2 to 25%, including the range of 20 to 21%, which is the oxygen concentration in the atmosphere. Other gas components besides oxygen gas, such as nitrogen gas, can be used. In general, the decomposition reaction is more favorable with higher oxygen gas concentrations, but this may also produce undesirable side reactions. Therefore, when the oxygen gas concentration is relatively high, it is necessary to appropriately control the reaction time, reaction temperature, etc. The partial pressure of oxygen gas is typically in the range of 0.001 to 1 MPa, preferably in the range of 0.01 to 0.8 MPa, and more preferably in the range of 0.02 to 0.5 MPa. On the other hand, when using air with an oxygen gas concentration of 20-21%, there is no need to prepare oxygen gas separately, which is advantageous in terms of equipment and economy. In reactions under an air atmosphere, if the amount of residue after step (B) to be decomposed is small, the decomposition reaction will proceed even in a sealed container with a sufficiently large internal volume. In that case, the internal volume of the reaction container is generally 50 volumes or more, and more preferably 100 volumes or more, per 1 volume of residue after step (B). When using pressurized air, the air pressure is typically in the range of 0.005 to 5 MPa, preferably in the range of 0.05 to 2 MPa, and more preferably in the range of 0.1 to 1 MPa.

[0098] When the decomposition reaction is carried out in a closed system, if the amount of residue after step (B) of the material to be decomposed is large, a reaction vessel with a large internal volume is required, which is not ideal from an equipment standpoint. Therefore, from an equipment standpoint, it is preferable to carry out the reaction in an open system that allows the flow of air, etc. To make the reaction system an open system, methods such as opening a part of the reaction vessel, installing a membrane that allows the flow of air, etc., or allowing air, etc. to overflow can be considered. Another advantageous method is to carry out the reaction while continuously or intermittently blowing air, etc., into the solution. In this case, there are no particular restrictions on the blowing rate, but it is usually 1 to 1000 mL / min, preferably 2 to 500 mL / min, and more preferably 3 to 200 mL / min per gram of residue after step (B). Furthermore, when using a solvent, it is preferable for safety reasons to keep the oxygen gas concentration in the reaction atmosphere outside the range of the explosion limits.

[0099] In the fifth decomposition method described above, the residue after step (B) to be decomposed may be immersed in a solvent to carry out the decomposition. By carrying out the reaction in a solvent, the decomposition of the residue after step (B) proceeds more easily. Here, any solvent that does not inhibit the decomposition reaction can be used as the solvent, for example, a solvent selected from hydrocarbons, halogenated hydrocarbons, nitrile compounds, ester compounds, ketone compounds, or mixtures thereof can be used.

[0100] If a solvent is used, a solvent with a boiling point in the range of 50 to 300°C is preferred, and a solvent with a boiling point in the range of 100 to 300°C is more preferred. When a solvent with a boiling point in the range of 100 to 300°C is selected from hydrocarbons, halogenated hydrocarbons, nitrile compounds, ester compounds, ketone compounds, or mixtures thereof, specific examples of these include the following: Examples of hydrocarbons include toluene, xylene, ethylbenzene, 1,3,5- or 1,2,4-trimethylbenzene, propylbenzene, p-cymene, diethylbenzene, methylcyclohexane, octane, nonane, and decane. Examples of halogenated hydrocarbons include chlorobenzene, 1,2-dichlorobenzene, 1,1,2-trichloroethane, and 1,1,2,2-tetrachloroethane. Examples of nitrile compounds include benzonitrile. Examples of ester compounds include methyl benzoate. Examples of ketone compounds include acetophenone. These solvents may be used in mixtures. Among these, toluene, xylene, ethylbenzene, p-cymene, diethylbenzene, methylcyclohexane, octane, 1,2-dichlorobenzene, benzonitrile, methyl benzoate, and acetophenone are preferred.

[0101] Furthermore, among hydrocarbons, toluene, xylene, and ethylbenzene are preferred from the viewpoint of reaction rate, availability, and cost. By using a preferred solvent, the decomposition of the residue after step (B) of the decomposition target is facilitated, and decomposition products mainly having an isoprene skeleton (particularly liquid polymers having an isoprene skeleton) can be produced more efficiently.

[0102] Furthermore, if the solvent used has a relatively low boiling point (for example, below 150°C), it is possible to raise the boiling point of the solvent by pressurizing it with an inert gas such as nitrogen gas, which is also advantageous for accelerating the decomposition reaction. When pressurizing with an inert gas such as nitrogen gas, the pressure can be set arbitrarily, but it is usually in the range of 0.05 to 1 MPa, preferably in the range of 0.05 to 0.8 MPa, and more preferably in the range of 0.05 to 0.6 MPa.

[0103] The amount of solvent used is preferably 2 mL or more, more preferably 10 mL or more, and more preferably 100 mL or less, and even more preferably 50 mL or less, per gram of residue after step (B) to be decomposed. If the amount of solvent used is 2 mL or more per gram of residue after step (B), the decomposition reaction of the residue after step (B) is promoted, and if the amount of solvent used is 50 mL or less per gram of residue after step (B), it is preferable in terms of cost.

[0104] The fifth decomposition method is usually carried out in a temperature range of 100 to 250°C, but preferably between 130°C and 220°C, and more preferably between 150°C and 200°C. By carrying out the fifth decomposition method at 150°C or higher, the rate of the decomposition reaction of the residue after step (B) is improved, and by carrying out the fifth decomposition method at 200°C or lower, the retention rate (selectivity) of the monomer skeleton in the residue after step (B) is improved.

[0105] When using a solvent in the fifth decomposition method described above, it is important to efficiently stir the residue after step (B) and the solvent in an atmosphere containing oxygen gas. Various conventionally known stirring methods can be used, such as using a magnetic stirrer, a mechanical stirrer, or a shaker. Furthermore, microwave irradiation, ultrasonic irradiation, light irradiation, etc., may be used in combination to accelerate the reaction. These can also be used in combination.

[0106] In the fifth decomposition method described above, when microwave irradiation is used as the heating method, various commercially available devices equipped with contact or non-contact temperature sensors can be used. Furthermore, the output of the microwave irradiation, the type of cavity (multimode, single-mode), the irradiation pattern (continuous, intermittent), etc., can be arbitrarily determined according to the scale and type of reaction. The microwave frequency is usually 0.3 to 30 GHz. Among these, the IMS frequency band allocated for use in industrial, scientific, and medical fields is preferred, and within that, the 2.45 GHz band and the 5.8 GHz band are more preferred.

[0107] When decomposition by microwave irradiation is carried out in a solvent, a solvent with a high dielectric loss coefficient and that readily absorbs microwaves is advantageous. Examples of such solvents include those with a large molecular dipole moment. Furthermore, solvents with high polymer solubility are also suitable for decomposition reactions. Specific examples of such solvents include 1,2-dichlorobenzene, benzonitrile, and nitrobenzene.

[0108] Furthermore, in microwave irradiation reactions, a heating material (susceptor) that absorbs microwaves and generates heat can be added to the reaction system to heat it more efficiently. Various conventionally known heating materials can be used, such as activated carbon, graphite, silicon carbide, and titanium carbide. Alternatively, a molded catalyst can be used, which is prepared by mixing the catalyst and heating material powders and firing them using a suitable binder such as sepiolite or formite. If the residue after the decomposition process (B) contains carbon black, the decomposition reaction by microwave irradiation proceeds more efficiently because carbon black readily absorbs microwaves.

[0109] -Other disassembly methods- The decomposition method in step (C) is not limited to the first, second, third, fourth, and fifth decomposition methods described above. The decomposition method in step (C) is preferably one in which 30% or more of the basic structure of the polymer is retained, more preferably one in which 50% or more of the polymer structure is retained, and even more preferably one in which 70% or more of the polymer structure is retained.

[0110] <Process (D)> The organic material decomposition method of this embodiment preferably further includes a step (D) of separating and recovering a liquid polymer having an isoprene skeleton from the decomposition products obtained in a step (C) of decomposing the residue after step (B). In step (C), the residue after step (B) is reduced in molecular weight to produce a liquid polymer. However, since the liquid polymer having a butadiene skeleton is recovered in step (B), the decomposition products obtained in step (C) are rich in liquid polymer having an isoprene skeleton. In addition to the liquid polymer, the decomposition products also contain undecomposed solid organic materials (crosslinked rubber, uncrosslinked rubber), undecomposed liquid organic materials (liquid polymer), and other compounding agents (carbon black, etc.). However, the liquid polymer with reduced molecular weight is easily recovered from the decomposition products. Therefore, it is possible to easily separate and recover the liquid polymer having an isoprene skeleton from the decomposition products obtained in step (C). Furthermore, the recovered liquid polymer having an isoprene skeleton can be used as is as a softening agent in rubber compositions, or it can be further decomposed (depolymerized) to be converted into isoprene monomer. Therefore, the organic material decomposition method including steps (A), (B), (C), and (D) can greatly contribute to promoting the reuse of organic materials.

[0111] The method for separating and recovering the liquid polymer having an isoprene skeleton from the decomposition product obtained in step (C) is not particularly limited. For example, if the raw material organic material is crosslinked rubber and / or uncrosslinked rubber, the liquid polymer having an isoprene skeleton can be easily separated and recovered by filtration. Also, if the raw material organic material is a liquid polymer, the liquid polymer having an isoprene skeleton, which is the product, has a much lower molecular weight than the raw material liquid polymer, so it can be easily separated and recovered by distillation or the like, or by precipitating the raw material liquid polymer using a poor solvent.

[0112] <Process (E)> The method for decomposing organic materials according to this embodiment preferably further includes step (E) of decomposing the liquid polymer having an isoprene skeleton to obtain isoprene monomer. The isoprene monomer obtained by decomposing (depolymerizing) the liquid polymer having an isoprene skeleton recovered in step (D) can be reused as a raw material for synthesizing diene rubber having an isoprene skeleton. Therefore, the method for decomposing organic materials including steps (A), (B), (C), (D), and (E) can greatly contribute to promoting the reuse of organic materials.

[0113] <Process (F)> The method for decomposing organic materials according to this embodiment preferably further includes step (F) of decomposing the liquid polymer having a butadiene skeleton to obtain a butadiene monomer. The butadiene monomer obtained by decomposing (depolymerizing) the liquid polymer having a butadiene skeleton recovered in step (B) can be reused as a raw material for synthesizing diene rubber having a butadiene skeleton. Therefore, the method for decomposing organic materials including steps (A), (B), and (F) can greatly contribute to promoting the reuse of organic materials.

[0114] <Process (G)> The method for decomposing organic materials in this embodiment may further include a step (G) in which the residue after step (B), in which the liquid polymer having the butadiene skeleton is separated and recovered, is decomposed to obtain isoprene monomer. As described above, the residue after step (B) is rich in organic materials having an isoprene skeleton. The organic material having an isoprene skeleton may be decomposed in step (C) as described above to convert it into a liquid polymer having an isoprene skeleton, and then decomposed (depolymerized) to obtain isoprene monomer, or the organic material having an isoprene skeleton may be directly decomposed (depolymerized) to obtain isoprene monomer. In particular, when the raw material organic material is a liquid polymer, the residue after step (B) is rich in liquid polymer having an isoprene skeleton, so isoprene monomer can be efficiently obtained even by direct decomposition (depolymerization). Therefore, the method for decomposing organic materials including steps (A), (B), and (G) can greatly contribute to promoting the reuse of organic materials.

[0115] <Decomposition (depolymerization) method> The decomposition (depolymerization) method for steps (E), (F), and (G) is not particularly limited, but for example, (i) A method of thermally decomposing the liquid polymer having an isoprene skeleton, the liquid polymer having a butadiene skeleton, and the residue after step (B) in an inert gas atmosphere and in the absence of a catalyst at 300°C to 450°C (first depolymerization method), (ii) A method of thermally decomposing the liquid polymer having an isoprene skeleton, the liquid polymer having a butadiene skeleton, and the residue after step (B) in an inert gas atmosphere and in the absence of a catalyst at 600°C to 950°C (second depolymerization method), (iii) A method of thermally decomposing the liquid polymer having an isoprene skeleton, the liquid polymer having a butadiene skeleton, and the residue after step (B) in an inert gas atmosphere and in the presence of a catalyst at 300°C to 950°C (third depolymerization method), These are some examples. The following describes these depolymerization methods in detail. In the following description of the depolymerization methods, the liquid polymer having the isoprene skeleton, the liquid polymer having the butadiene skeleton, and the residue after step (B) may simply be referred to as "raw materials."

[0116] -First depolymerization method- In the first depolymerization method described above, performing the decomposition (depolymerization) of the raw materials at 300°C or higher improves the rate of the decomposition reaction of the raw materials and improves the yield of monomers. Furthermore, performing the decomposition (depolymerization) of the raw materials at 450°C or lower significantly suppresses the gasification and aromatization of the decomposition products, and significantly improves the selectivity of products that maintain the monomer skeleton. From the viewpoint of improving the decomposition reaction rate and improving the monomer yield, the decomposition (depolymerization) is preferably performed at 320°C or higher, and from the viewpoint of suppressing the gasification and aromatization of the decomposition products, it is preferably performed at 380°C or lower.

[0117] The first depolymerization method described above is carried out under an inert gas atmosphere. By carrying out the decomposition (depolymerization) under an inert gas atmosphere, oxidation and reduction of the decomposition products can be suppressed, and in particular, hydrogenation of double bonds in the monomers of the decomposition products can be suppressed. Examples of inert gases include nitrogen, carbon dioxide, argon, and helium. To carry out the decomposition (depolymerization) under an inert gas atmosphere, for example, when using a batch reactor, the atmosphere charged into the reactor should be an inert gas, and when using a flow-through reactor, the atmosphere flowing through the reactor should be an inert gas. Although hydrogen may be generated during the decomposition (depolymerization), the generated hydrogen is not taken into consideration when determining the atmosphere for the decomposition (depolymerization).

[0118] The aforementioned decomposition (depolymerization) can be carried out at any pressure, including under reduced pressure, atmospheric pressure, or under pressure, but it is preferable to carry it out under reduced pressure or atmospheric pressure. As an example, the reaction pressure for the aforementioned decomposition (depolymerization) is preferably 1000 kPa to 67 kPa. By carrying out the aforementioned decomposition (depolymerization) under reduced pressure or atmospheric pressure, polymerization (repolymerization) of the monomers of the decomposition products can be suppressed.

[0119] The reaction time for the decomposition (depolymerization) is not particularly limited. For example, the reaction time for the decomposition (depolymerization) is preferably 3 to 60 minutes, and more preferably 5 to 30 minutes.

[0120] The aforementioned decomposition (depolymerization) is carried out in the absence of a catalyst (i.e., without using a catalyst). By not using a catalyst in the aforementioned decomposition (depolymerization), costs can be reduced. Here, "absence of a catalyst" means that there is no catalyst in the reaction system of the aforementioned decomposition (depolymerization) that has the effect of promoting the decomposition reaction.

[0121] -Second depolymerization method- In the second depolymerization method described above, by performing the decomposition (depolymerization) of the raw materials at 600°C or higher, the rate of the decomposition reaction of the raw materials is greatly improved, and the yield of monomers is greatly improved. Furthermore, by performing the decomposition (depolymerization) of the raw materials at 950°C or lower, gasification and aromatization of the decomposition products can be suppressed, and the selectivity of products that maintain the monomer skeleton can be improved. From the viewpoint of improving the decomposition reaction rate and improving the monomer yield, the decomposition (depolymerization) is preferably performed at 700°C or higher. Moreover, by performing the decomposition (depolymerization) at 700°C to 900°C, it is possible to improve the rate of the decomposition reaction of the raw materials while improving the selectivity of products that maintain the monomer skeleton.

[0122] The second depolymerization method described above is carried out under an inert gas atmosphere. By carrying out the decomposition (depolymerization) under an inert gas atmosphere, oxidation and reduction of the decomposition products can be suppressed, and in particular, hydrogenation of double bonds in the monomers of the decomposition products can be suppressed. Examples of inert gases include nitrogen, carbon dioxide, argon, and helium. To carry out the decomposition (depolymerization) under an inert gas atmosphere, for example, if a batch reactor is used, the atmosphere charged into the reactor should be an inert gas, and if a flow reactor is used, the atmosphere flowing through the reactor should be an inert gas. Although hydrogen may be generated during the decomposition (depolymerization), the generated hydrogen is not taken into consideration when determining the atmosphere for the decomposition (depolymerization).

[0123] The aforementioned decomposition (depolymerization) can be carried out at any pressure, including under reduced pressure, atmospheric pressure, or under pressure, but it is preferable to carry it out under reduced pressure or atmospheric pressure. As an example, the reaction pressure for the aforementioned decomposition (depolymerization) is preferably 1000 kPa to 65 kPa. By carrying out the aforementioned decomposition (depolymerization) under reduced pressure or atmospheric pressure, polymerization (repolymerization) of the monomers of the decomposition products can be suppressed.

[0124] The reaction time for the decomposition (depolymerization) is not particularly limited. For example, the reaction time for the decomposition (depolymerization) is preferably 0.001 seconds to 1000 seconds, and more preferably 0.01 seconds to 1000 seconds.

[0125] The aforementioned decomposition (depolymerization) is carried out in the absence of a catalyst (i.e., without using a catalyst). By not using a catalyst in the aforementioned decomposition (depolymerization), costs can be reduced. Here, "absence of a catalyst" means that there is no catalyst in the reaction system of the aforementioned decomposition (depolymerization) that has the effect of promoting the decomposition reaction.

[0126] -Third depolymerization method- In the third depolymerization method described above, the rate of the decomposition reaction of the raw materials is improved by performing the decomposition (depolymerization) of the raw materials at 300°C or higher, and the selectivity of the product that maintains the monomer skeleton is improved by performing the decomposition (depolymerization) of the raw materials at 950°C or lower. From the viewpoint of improving the rate of the decomposition reaction, a temperature of 500°C or higher is more preferable, and from the viewpoint of improving the selectivity of the product that maintains the monomer skeleton, a temperature of 900°C or lower is even more preferable.

[0127] The third depolymerization method described above is carried out under an inert gas atmosphere. By carrying out the decomposition (depolymerization) under an inert gas atmosphere, oxidation and reduction of the decomposition products can be suppressed, and in particular, hydrogenation of double bonds in the monomers of the decomposition products can be suppressed. Examples of inert gases include nitrogen, carbon dioxide, argon, and helium. To carry out the decomposition (depolymerization) under an inert gas atmosphere, for example, when using a batch reactor, the atmosphere charged into the reactor should be an inert gas, and when using a flow-through reactor, the atmosphere circulated through the reactor should be an inert gas. Although hydrogen may be generated during the decomposition (depolymerization), the generated hydrogen is not taken into consideration when determining the atmosphere for the decomposition (depolymerization).

[0128] The aforementioned decomposition (depolymerization) may be carried out, for example, under pressure, by thermally decomposing the raw materials in a solvent. Here, any solvent that does not inhibit the decomposition reaction can be used as the solvent, and examples include aromatic solvents, chlorinated hydrocarbons, aliphatic solvents, alicyclic solvents, ethers, esters, nitriles, and the like. Examples of aromatic solvents include benzene, toluene, xylene, benzonitrile, diethylbenzene, o-dichlorobenzene, p-cymene, and 1,2,4-trimethylbenzene. Specific examples of chlorinated hydrocarbons include chloroform, dichloromethane, dichloroethane, trichloroethane, tetrachloroethane, tetrachloroethene, chlorobenzene, and dichlorobenzene. Examples of aliphatic solvents include pentane, hexane, and heptane. Examples of alicyclic solvents include cyclopentane and cyclohexane. Examples of ethers include tetrahydrofuran (THF), cyclopentyl methyl ether, and 4-methyltetrahydropyran. Examples of esters include ethyl acetate, butyl acetate, and methyl benzoate. Examples of nitriles include benzonitrile and acetonitrile. The organic solvent is preferably at least one selected from the group consisting of toluene, xylene, benzonitrile, diethylbenzene, o-dichlorobenzene, p-cymene, 1,2,4-trimethylbenzene, and cyclohexane. When a liquid polymer is dissolved or dispersed in an organic solvent selected from toluene, xylene, benzonitrile, diethylbenzene, o-dichlorobenzene, p-cymene, 1,2,4-trimethylbenzene, and cyclohexane, the liquid polymer is dispersed in the solvent at a molecular level, the spacing between liquid polymer particles widens, the formation of degradation products with higher molecular weight than the monomer, such as oligomers, is further suppressed, and the monomer yield is further improved.

[0129] The amount of solvent used is preferably 10 mL or more per gram of raw material, more preferably 50 mL or more, more preferably 500 mL or less, and more preferably 200 mL or less. If the amount of solvent used is 10 mL or more per gram of raw material, the decomposition reaction proceeds further, and if the amount of solvent used is 500 mL or less per gram of raw material, it is preferable in terms of cost.

[0130] The third depolymerization method described above is carried out in the presence of a catalyst. Here, the catalyst may be an acidic catalyst, a neutral catalyst, or a basic catalyst, and among these, a basic catalyst is preferred. It is even more preferable to carry out the depolymerization in the presence of at least one basic catalyst selected from the group consisting of TiO2, ZrO2, MgO, La2O3, CeO2, Y2O3, Li2CO3, Na2CO3, Rb2CO3, and Cs2CO3. By carrying out the decomposition (depolymerization) in the presence of these basic catalysts, the rate of the decomposition reaction (depolymerization reaction) of the raw materials is improved, and the selectivity of the product that maintains the monomer skeleton is improved. These catalysts may be used individually or in combination of two or more.

[0131] The amount of catalyst used is preferably 1 part by mass or more, more preferably 10 parts by mass or more, even more preferably 100 parts by mass or more, and also preferably 8000 parts by mass or less, even more preferably 4000 parts by mass or less, and even more preferably 500 parts by mass or less, per 100 parts by mass of the raw material. If the amount of catalyst used is 100 parts by mass or more per 100 parts by mass of the raw material, the decomposition reaction proceeds further, and if the amount of catalyst used is 500 parts by mass or less per 100 parts by mass of the raw material, it is preferable in terms of cost.

[0132] -Depolymerization products- The depolymerization yields isoprene and / or 1,3-butadiene as decomposition products. Depending on the type of rubber component in the raw material organic material, other products such as 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and limonene may also be obtained in addition to isoprene and / or 1,3-butadiene. From the viewpoint of yielding reusable monomers, the decomposition products obtained by depolymerization preferably contain 15% by mass or more of isoprene and / or 1,3-butadiene, more preferably 20% by mass or more, even more preferably 25% by mass or more, and particularly preferably 40% by mass or more.

[0133] <Other> The organic material decomposition method of this embodiment may include further steps in addition to the steps described above. Such steps include pretreatment steps for crosslinked rubber or uncrosslinked rubber (for example, cutting steps, grinding steps, etc.). Furthermore, if the crosslinked rubber or uncrosslinked rubber contains carbon black, it is preferable to include a step for recovering carbon black from the decomposition products (intermediate decomposition products). [Examples]

[0134] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0135] <Rubber composition used in the decomposition reaction> Rubber samples with the formulations shown in Table 1 were prepared. In Table 1, NR represents natural rubber (polyisoprene) and BR represents butadiene rubber (polybutadiene).

[0136] [Table 1]

[0137] <Selective decomposition of mixed rubber (Examples corresponding to processes A and B)> (Example 1, Selective decomposition of rubber 1) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M102 catalyst (M102, manufactured by Umicore, Merck product number 579726) were mixed with 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 2 mg and 1.6% by mass for the isoprene skeleton component, and 47.1 mg and 37.7% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 95.9%.

[0138] (Example 2, Selective decomposition of rubber 2) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 2) and 8 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 2 were 1.8 mg and 1.4% by mass for the isoprene skeleton component, and 31.3 mg and 25% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 94.6%.

[0139] (Example 3, Selective decomposition of waste rubber 1) 125 mg of waste tire rubber (waste rubber 1) and 8 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of waste rubber 1 were 2.8 mg and 2.2% by mass for the isoprene skeleton component, and 30.1 mg and 24.1% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 91.5%.

[0140] (Example 4, Selective decomposition of waste rubber 2) 125 mg of waste tire rubber (waste rubber 2) and 9 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of waste rubber 2 were 1.3 mg and 1.0% by mass for the isoprene skeleton component, and 14.2 mg and 11.4% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 91.6%.

[0141] (Example 5, Selective decomposition of waste rubber 3) 125 mg of waste tire rubber (waste rubber 3) and 8 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of waste rubber 3 were 1.4 mg and 1.1% by mass for the isoprene skeleton component, and 11.5 mg and 9.2% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 89.1%.

[0142] (Example 6, Solvent consideration: Hexane) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M102 catalyst were added to 5 mL of hexane and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 1.4 mg and 1.1% by mass for the isoprene skeleton component, and 47 mg and 37.6% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 97.1%.

[0143] (Example 7, Solvent Investigation: THF) 125 mg of polyisoprene / polybutadiene mixed rubber (rubber 1) and 9 mg of metathesis M102 catalyst were added to 5 mL of THF and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 4.2 mg and 3.4% by mass for the isoprene skeleton component, and 47.1 mg and 37.7% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 91.8%.

[0144] (Example 8, Solvent consideration: CH2Cl2) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M102 catalyst were added to 25 mL of CH2Cl and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 2.6 mg and 2.1% by mass for the isoprene skeleton component, and 44.6 mg and 35.7% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 94.5%.

[0145] (Example 9, Solvent Investigation: Cyclohexane) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M102 catalyst were added to 5 mL of cyclohexane and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 1.3 mg and 1.0% by mass for the isoprene backbone component, and 39.2 mg and 31.4% by mass for the butadiene backbone component, respectively, with a rubber selectivity of 96.8%.

[0146] (Example 10, catalyst amount 1 / 2) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 4 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.9 mg and 0.7 mass% for the isoprene skeleton component, and 30.2 mg and 24.2 mass% for the butadiene skeleton component, respectively, with a rubber selectivity of 97.1%.

[0147] (Example 11, catalyst amount 1 / 4) 125 mg of polyisoprene / polybutadiene mixed rubber (rubber 1) and 2 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.6 mg and 0.5 mass% for the isoprene skeleton component, and 18.5 mg and 14.8 mass% for the butadiene skeleton component, respectively, with a rubber selectivity of 96.9%.

[0148] (Example 12, catalyst amount 1 / 2, reaction time 2x) 125 mg of polyisoprene / polybutadiene mixed rubber (rubber 1) and 4 mg of metathesis M102 catalyst were added to 5 mL of toluene and stirred for 48 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.8 mg and 0.6% by mass for the isoprene backbone component, and 25.7 mg and 20.6% by mass for the butadiene backbone component, respectively, with a rubber selectivity of 97%.

[0149] (Example 13, Catalyst study M700, 25℃) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 6 mg of metathesis M700 catalyst (Yumicore M700, Merck product number 577944) were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.6 mg and 0.5 mass% for the isoprene skeleton component, and 6.1 mg and 4.9 mass% for the butadiene skeleton component, respectively, with a rubber selectivity of 91%.

[0150] (Example 14, Catalyst study M700, 40℃) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 6 mg of metathesis M700 catalyst (Yumicore M700, Merck product number 577944) were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 40°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.5 mg and 0.4% by mass for the isoprene skeleton component, and 11.4 mg and 9.1% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 95.8%.

[0151] (Example 15, Catalyst study M700, 60℃) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 6 mg of metathesis M700 catalyst (M700, manufactured by Umicore, Merck product number 577944) were added to 5 mL of toluene and stirred for 24 hours at 60°C under a nitrogen atmosphere. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 1.2 mg and 1% by mass for the isoprene skeleton component, and 43.9 mg and 35.1% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 97.3%.

[0152] (Example 16, Catalyst study M700, 80℃) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 6 mg of metathesis M700 catalyst (M700, manufactured by Umicore, Merck product number 577944) were added to 5 mL of toluene and stirred for 24 hours at 80°C under a nitrogen atmosphere. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 3.3 mg and 2.6% by mass for the isoprene skeleton component, and 43.4 mg and 34.7% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 92.9%.

[0153] (Example 17, Catalyst Study M360) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 7 mg of metathesis M360 catalyst (M360, manufactured by Umicore, Merck product number 682381) were mixed with 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue containing the isoprene skeleton component was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 0.8 mg and 0.6% by mass for the isoprene backbone component, and 25.7 mg and 20.6% by mass for the butadiene backbone component, respectively, with a rubber selectivity of 97%.

[0154] <Butadiene degradation with low selectivity (comparative example)> (Comparative Example 1, Catalyst Study M204) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M204 catalyst (M204, manufactured by Umicore, Merck product number 569747) were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 27.3 mg and 21.8% by mass for the isoprene skeleton component, and 40.8 mg and 32.6% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 59.9%.

[0155] (Comparative Example 2, Catalyst Study M720) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 7 mg of metathesis M720 catalyst (M720, manufactured by Umicore, Merck product number 569755) were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 31.3 mg and 25% by mass for the isoprene skeleton component, and 41.3 mg and 33% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 56.9%.

[0156] (Comparative Example 3, Catalyst Study M202) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 10 mg of metathesis M202 catalyst (M202, manufactured by Umicore, Merck product number 775258) were mixed with 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 29.1 mg and 23.3% by mass for the isoprene skeleton component, and 32.9 mg and 26.3% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 53.1%.

[0157] (Comparative Example 4, Catalyst Study M207) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M207 catalyst (M207, manufactured by Umicore, Merck product number 682365) were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 30.9 mg and 24.7% by mass for the isoprene skeleton component, and 29.6 mg and 23.7% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 48.9%.

[0158] (Comparative Example 5, Catalyst Study M209) 125 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 9 mg of metathesis M209 catalyst (M209, manufactured by Umicore, Merck product number 915483) were mixed with 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by centrifugation. The filtrate and the washing solution obtained by washing the residue with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of rubber 1 were 8.8 mg and 7% by mass for the isoprene skeleton component, and 28.5 mg and 22.8% by mass for the butadiene skeleton component, respectively, with a rubber selectivity of 76.4%.

[0159] [Table 2]

[0160] <Metathesis decomposition of residues obtained by selective decomposition (Examples corresponding to Steps C and D)> (Example 18, decomposition of residue obtained from Rubber 1) To 72 mg of the residue obtained in Example 1 and 4 mg of the metathesis M204 catalyst, 5 mL of toluene was added, and the mixture was stirred at 25 °C under a nitrogen atmosphere for 24 hours. After the reaction, 5 mL of methanol was added to deactivate the catalyst, then toluene was added, and carbon black was separated by centrifugation. The filtrate and the washing liquid obtained by washing the carbon black with toluene were combined and concentrated under reduced pressure. 1 By 1H NMR measurement, the yield and the yield percentage (mass% with respect to the charged residue) of the soluble polymer produced by the decomposition of the residue were calculated to be 25.2 mg and 20.2 mass% for the isoprene skeleton component, and 0.7 mg and 0.6 mass% for the butadiene skeleton component, respectively.

[0161] (Example 19, decomposition of residue obtained from Rubber 2) To 90 mg of the residue obtained in Example 2 and 4 mg of the metathesis M204 catalyst, 5 mL of toluene was added, and the mixture was stirred at 25 °C under a nitrogen atmosphere for 24 hours. After the reaction, 5 mL of methanol was added to deactivate the catalyst, then toluene was added, and carbon black was separated by centrifugation. The filtrate and the washing liquid obtained by washing the carbon black with toluene were combined and concentrated under reduced pressure. 1 By 1H NMR measurement, the yield and the yield percentage (mass% with respect to the charged residue) of the soluble polymer produced by the decomposition of the residue were calculated to be 41 mg and 32.8 mass% for the isoprene skeleton component, and 0.1 mg and 0.1 mass% for the butadiene skeleton component, respectively.

[0162] (Example 20, decomposition of residue obtained from waste rubber 1) 90 mg of the residue obtained in Example 3 and 4 mg of Metathesis M204 catalyst were added to 5 mL of toluene and stirred under a nitrogen atmosphere at 25°C for 24 hours. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the carbon black was separated by centrifugation. The filtrate and the washing solution obtained by washing the carbon black with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 41 mg and 32.8% by mass for the isoprene skeleton component, and 0.1 mg and 0.1% by mass for the butadiene skeleton component, respectively.

[0163] (Example 21: Decomposition of residue obtained from waste rubber 2) 105 mg of the residue obtained in Example 4 and 6 mg of Metathesis M204 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the carbon black was separated by centrifugation. The filtrate and the washing solution obtained by washing the carbon black with toluene were combined and concentrated under reduced pressure. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 65.8 mg and 52.6% by mass for the isoprene skeleton component, and 0.2 mg and 0.2% by mass for the butadiene skeleton component, respectively.

[0164] (Example 22: Decomposition of residue obtained from waste rubber 3) 112 mg of the residue obtained in Example 5 and 6 mg of Metathesis M204 catalyst were added to 5 mL of toluene and stirred for 24 hours under a nitrogen atmosphere at 25°C. After the reaction, 5 mL of methanol was added to inactivate the catalyst, then toluene was added, and the carbon black was separated by centrifugation. The filtrate and the washing solution obtained by washing the carbon black with toluene were combined and concentrated under reduced pressure. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 36.5 mg and 29.2% by mass for the isoprene backbone component, and 0.3 mg and 0.2% by mass for the butadiene backbone component, respectively.

[0165] [Table 3]

[0166] 1) The catalyst used is as follows: M102: Ru(PCy3)2 (benzylidene)Cl2 (M102 manufactured by Umicore, Merck product number 579726). M700:Ru(PCy3)(2-isopropoxyphenylmethylene)Cl2 (M700 manufactured by Umicore, Merck product number 577944). M360:(SIMes)Ru(3-(2-pyridinyl)propyridene)Cl2 (Merck product number 682381). M204: (SIMes)Ru(PCy3)(benzylidene)Cl2 (M204 manufactured by Umicore, Merck product number 569747). M720: (SIMes)Ru(2-isopropoxyphenylmethylene)Cl2 (M720 manufactured by Umicore, Merck product number 569755). M202: (SIMes)Ru(PCy3)(3-phenyl-1H-inden-1-ylidene)Cl2 (M202 manufactured by Umicore, Merck product number 775258). M207: (SIMes)Ru(PCy3)(3-methyl-2-butenylidene)Cl2 (M207 manufactured by Umicore, Merck product number 682365). M209: (IMes)Ru(PCy3)(2-thienylmethylene)Cl2 (M209 manufactured by Umicore, Merck product number 915483). [ka]

[0167] 2) The weights of the isoprene and butadiene product are:1 It was calculated by 1H NMR. 3) The yield was calculated based on the following formula using the weight of isoprene and butadiene products relative to the weight of the raw rubber. Yield (%) = [weight of product (mg) × 100 (%)] / weight of raw rubber (mg) 4) The selectivity was calculated based on the following formula using the weight of butadiene relative to the total weight of isoprene and butadiene products. Selectivity (%) = [weight of butadiene (mg) × 100 (%)] / [weight of butadiene (mg) + weight of isoprene (mg)]

[0168] (Example 23, Selective Degradation of Rubber 1) 100 mL of toluene was added to 2499 mg of polyisoprene / polybutadiene mixed rubber (Rubber 1) and 175 mg of metathesis M102 catalyst, and the mixture was stirred at 25 °C under a nitrogen atmosphere for 24 hours. After the reaction, 100 mL of methanol was added to inactivate the catalyst, then toluene was added, and the residue was separated by filtration. The filtrate and the toluene washings of the residue were combined and concentrated under reduced pressure to obtain a concentrate (soluble polymer composition) containing the soluble polymer. 1 By 1H NMR measurement, the yield and the yield (mass% relative to the charged Rubber 1) of the soluble polymer produced by the degradation of Rubber 1 were calculated to be 16 mg and 0.6 mass% for the isoprene backbone component and 852 mg and 34 mass% for the butadiene backbone component, respectively, and the selectivity was calculated to be 98%. Also, the yield and the yield (mass% relative to the charged Rubber 1) of the residue separated by filtration after drying were 1702 mg and 68 mass%, respectively.

[0169] (Examples of Steps (C) and (D) (Reactions Other than Metathesis Degradation)) (Example 24) A mixture of 300 mg of the residue obtained in Example 23 and 3 mL of toluene was placed in a stainless steel autoclave, and under air pressurization conditions (absolute pressure 0.7 MPa), stirred with a magnetic stirrer with a stir bar at 180 °C for 1 hour to conduct a decomposition reaction. 1¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 92 mg and 31% by mass for the isoprene backbone component, and 4 mg and 1% by mass for the butadiene backbone component, respectively. GPC measurements also yielded the total molecular weight of the soluble polymer as Mw=45300, Mn=18400, and Mw / Mn=2.5. The reaction solution was diluted with toluene, the insoluble solid was separated by centrifugation, and the insoluble carbon black component was recovered by heating and drying under vacuum (167 mg, 56% by mass). Meanwhile, the supernatant was concentrated under reduced pressure, resulting in a soluble polymer composition mainly composed of isoprene skeleton (113 mg, 38% by mass). An internal standard substance (hexamethyldisilane) was added. 1 ¹H NMR measurements revealed that the yields of the isoprene and butadiene skeleton components in the soluble polymer composition were 87 mg and 29% by mass, and 3 mg and 1% by mass, respectively. Furthermore, GPC measurements calculated the total molecular weight of the soluble polymer as Mw=49400, Mn=20000, and Mw / Mn=2.5.

[0170] (Example 25) A mixture of 300 mg of the residue obtained in Example 23 and 1.5 mL of methyl benzoate was placed in a sealed glass vial and stirred with a magnetic stirrer using a stirring bar at 180°C for 1 hour under an air atmosphere (absolute pressure 0.1 MPa) to carry out the decomposition reaction. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 88 mg and 29% by mass for the isoprene backbone component, and 3 mg and 1% by mass for the butadiene backbone component, respectively. GPC measurements also yielded the total molecular weight of the soluble polymer as Mw=46100, Mn=17900, and Mw / Mn=2.6. The reaction solution was diluted with toluene, the insoluble solid was separated by centrifugation, and the insoluble carbon black component was recovered by heating and drying under vacuum (158 mg, 53% by mass). Meanwhile, the supernatant was concentrated under reduced pressure, resulting in a soluble polymer composition mainly composed of isoprene skeleton (109 mg, 36% by mass). An internal standard substance (hexamethyldisilane) was added. 1 ¹H NMR measurements revealed that the yields of the isoprene and butadiene skeleton components in the soluble polymer composition were 85 mg and 28% by mass, and 3 mg and 1% by mass, respectively. Furthermore, GPC measurements calculated the total molecular weight of the soluble polymer as Mw=45600, Mn=17700, and Mw / Mn=2.6.

[0171] (Example 26) A mixture of 300 mg of the residue obtained in Example 23, 28 mg of benzoyl peroxide (hydrated, 75% purity) as a radical initiator, and 4.8 mL of toluene was placed in a sealed glass vial and stirred with a magnetic stirrer using a stirring bar for 1 day at 25°C under an air atmosphere (absolute pressure 0.1 MPa) to carry out the decomposition reaction. 1 ¹H NMR measurements revealed that the yield and yield (mass %) of the soluble polymer produced by the decomposition of the residue were 71 mg and 24% by mass for the isoprene backbone component, and 3 mg and 1% by mass for the butadiene backbone component, respectively. GPC measurements also yielded the total molecular weight of the soluble polymer as Mw=42700, Mn=17500, and Mw / Mn=2.4.

[0172] <Example of process (E)> (Example 27) The soluble polymer composition obtained in Example 24 is dissolved in toluene to prepare a 5 mg / mL solution. A portion of this solution, 5.0 μL, is taken into a stainless steel container and the solvent is removed by distillation. 25 μg of the soluble polymer composition obtained after solvent removal is heated to 750°C using a pyrolizer, and the resulting pyrolysis products are analyzed by GC. The estimated yields (mass %) of isoprene, hydrocarbons with 1-4 carbon atoms, and hydrocarbons with 5-10 carbon atoms (other than isoprene) are estimated to be 35% by mass, 15% by mass, and 35% by mass, respectively.

[0173] <Example of process (F)> (Example 28) The soluble polymer composition obtained in Example 23 is dissolved in toluene to prepare a 5 mg / mL solution. A portion of this solution, 5.0 μL, is taken into a stainless steel container and the solvent is removed by distillation. 25 μg of the soluble polymer composition obtained after solvent removal is heated to 750°C using a pyrolizer, and the resulting pyrolysis products are analyzed by GC. The estimated yields (mass %) of butadiene, hydrocarbons with 1-4 carbon atoms (other than butadiene), and hydrocarbons with 5-10 carbon atoms (relative to the initial soluble polymer composition) are estimated to be 20% by mass, 20% by mass, and 30% by mass, respectively.

[0174] <Example of process (G)> (Example 29) When 0.1 mg of the residue obtained in Example 23 is collected in a stainless steel container and heated to 750°C using a pyrolyzer, the estimated yields (mass %) of isoprene, hydrocarbons with 1 to 4 carbon atoms, and hydrocarbons with 5 to 10 carbon atoms (other than isoprene) when the resulting pyrolysis products are analyzed by GC are estimated to be 15% by mass, 10% by mass, and 20% by mass, respectively.

Claims

1. A method for decomposing an organic material, comprising the step (A) of mixing at least one organic material selected from crosslinked rubber, uncrosslinked rubber, and liquid polymer having at least both a butadiene skeleton and an isoprene skeleton with a catalyst to decompose it, The catalyst is defined by the following general formula (a), (b), or (c): 【Chemistry 1】 [In the formula, R ａ , R ｂ , R ｃ , R ｄ , R ｅ , R ｆ and R ｇ Each of these is independently an alkyl group, a cycloalkyl group, or an aryl group. X ａ and X ｂ are each independently Cl, Br or I, A method for decomposing organic materials, characterized by being represented as [L is an N-heterocyclic carbene (NHC) ligand].

2. The method for decomposing an organic material according to claim 1, wherein the liquid polymer has a weight-average molecular weight of 10,000 or more.

3. The method for decomposing an organic material according to claim 1, further comprising the step (B) of separating and recovering a liquid polymer having a butadiene skeleton from the decomposition product obtained in the step (A) of mixing the organic material with a catalyst to decompose it.

4. The method for decomposing an organic material according to claim 3, further comprising a step (C) of decomposing the residue after a step (B) of separating and recovering the liquid polymer having the butadiene skeleton.

5. The method for decomposing an organic material according to claim 4, further comprising a step (D) of separating and recovering a liquid polymer having an isoprene skeleton from the decomposition product obtained in the step (C) of decomposing the aforementioned residue.

6. The method for decomposing an organic material according to claim 5, further comprising the step (E) of decomposing the liquid polymer having the isoprene skeleton to obtain an isoprene monomer.

7. The method for decomposing an organic material according to claim 3, further comprising the step (F) of decomposing the liquid polymer having the butadiene skeleton to obtain a butadiene monomer.

8. The method for decomposing an organic material according to claim 3, further comprising the step (G) of decomposing the residue after the step (B) of separating and recovering the liquid polymer having the butadiene skeleton to obtain an isoprene monomer.

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