Method for producing mesophase pitch, method for producing carbon fiber, method for producing needle coke, method for producing binder, method for producing mesocarbon microbeads, and method for producing material for carbon electrode

Abstract

A method for producing a mesophase pitch having: a first production method comprising a first step for preparing a dehydrogenated product of terpenes, and a second step for polymerizing the dehydrogenated product to obtain a mesophase pitch; or a second production method comprising a third step for preparing a polymer of terpenes, and a fourth step for dehydrogenating the polymer to obtain a mesophase pitch. Abietic acid and the like are used as the terpenes.

Description

Methods for producing mesophase pitch, methods for producing carbon fiber, methods for producing needle coke, methods for producing binders, methods for producing mesocarbon microbeads, and methods for producing carbon electrode materials

[0001] This disclosure relates to a method for producing mesophase pitch, a method for producing carbon fiber, a method for producing needle coke, a method for producing binders, a method for producing mesocarbon microbeads, and a method for producing carbon electrode materials. This application claims priority based on Japanese Patent Application No. 2024-090123, filed on June 3, 2024, the contents of which are incorporated herein by reference.

[0002] Mesophase pitch is known to exhibit optical anisotropy upon heating, and its use as a raw material for the production of high-performance carbon materials is being investigated. For example, needle coke is obtained by coking mesophase pitch in a coker and then calcining it in a calciner, and various carbon electrode materials can be obtained from the needle coke. Furthermore, binders can be obtained from mesophase pitch. Furthermore, mesophase carbon fibers can be obtained by hot spinning mesophase pitch. Furthermore, mesocarbon microbeads can be obtained by heating mesophase pitch.

[0003] Coal-based pitch and petroleum-based pitch have been used as raw materials for mesophase pitch. For example, a known coal-based pitch is a pitch obtained by modifying coal tar, a by-product of the production of coke for steelmaking. For example, a known petroleum-based pitch is a pitch obtained by modifying heavy oil (FCC bottom oil) obtained by fluid catalytic cracking (FCC) during petroleum refining, or a heavy component such as solvent deasphalting residue.

[0004] On the other hand, coal-based pitch and petroleum-based pitch, which are raw materials for producing mesophase pitch, are derived from fossil fuels, and therefore their supply is limited. Furthermore, while demand for mesophase pitch is expected to increase in the future, demand for fossil fuels is expected to decrease due to societal demand for carbon-neutral energy sources. As a result, there are concerns about a decrease in the supply of coal-based pitch and petroleum-based pitch. For example, the introduction of electric furnaces in the steel industry is promoted, and the resulting decline in the operating rates of blast furnaces and coke ovens is expected to result in a decrease in coal tar production. Furthermore, the widespread use of electric vehicles is expected to reduce the use of gasoline and diesel fuels, leading to a decrease in the production of FCC bottom oil at refineries. Therefore, the use of previously unused fossil fuels as raw materials for producing mesophase pitch is being considered. For example, a method for producing mesophase pitch using previously unused lignite in combination with petroleum residue or its modified product has been disclosed (see Patent Document 1).

[0005] However, it is desirable to utilize natural products other than fossil resources as raw materials for producing mesophase pitch. Patent Document 2 discloses a method for producing such mesophase pitch, in which a mixture of aromatic hydrocarbon oil and biomass is subjected to a co-carbonization reaction using a co-carbonization agent to obtain mesophase pitch. It is also disclosed that the aromatic hydrocarbon oil may be, for example, a pretreated catalyst oil slurry, vacuum distillate oil, ethylene tar, coal tar, or the like, and the biomass may be, for example, wood chips, lignin, chitosan, biomass pyrolysis oil, or the like.

[0006] Furthermore, it has been disclosed that phenolated sawdust obtained by reacting pine sawdust with phenol contains carbonaceous mesophase (see Non-Patent Document 1). Furthermore, it has been disclosed that mesophase pitch can be obtained by adding gum rosin to a polymerization process of petroleum vacuum residue from which asphalt has been removed (see Non-Patent Document 2).

[0007] Terpenes are known as natural products derived from pine trees. Among terpenes, chain (acyclic) terpenes can be converted into cyclic terpenes by known methods (see Non-Patent Documents 3 and 4).

[0008] Japanese Patent Publication No. 2023-161310 Chinese Patent Application Publication No. 112812801

[0009] J. Zhao et al., “Observation of carbonaceous mesophase behaviors in phenolated sawdust using polarized light microscopy”, J. Mater. Sci, (2007), 42, pp.6735-6741.Dijan Supramono and Aegerin Hafiz Sucipto, “Polymerization of deasphalted vacuum residue mixed with gum rosin for mesophase pitch production”, AIP Conf. Proc. 2062, 020050 (2019).SUMIT GHOSH, “Biosynthesis of Structurally Diverse Triterpenes in Plants: the Role of Oxidosqualene Cyclases”, Proc Indian Natn Sci Acad 82 No.4 September 2016 pp.1189-1210.Jose' Francisco Quilez del Moral et al., “Chemical synthesis of terpenoids with participation of Cyclizations plus rearrangements of carbocations: a current overview”, Phytochem Rev 19, 559-576 (2020).

[0010] However, although the methods disclosed in Patent Document 2 and Non-Patent Documents 1 and 2 all use biomass-derived raw materials, they also use raw materials derived from fossil resources, and the use of raw materials derived from fossil resources is still essential. On the other hand, Non-Patent Documents 3 and 4 do not disclose that the chain terpenes and cyclic terpenes disclosed therein can be used alone to produce mesophase pitch.

[0011] An object of the present disclosure is to provide a method for producing mesophase pitch that can produce mesophase pitch without using raw materials derived from fossil resources.

[0012] One embodiment of the present disclosure is a method for producing mesophase pitch, comprising: a first production method including a first step of preparing a dehydrogenated product of terpenes and a second step of polymerizing the dehydrogenated product to obtain mesophase pitch; or a second production method including a third step of preparing a polymer of terpenes and a fourth step of dehydrogenating the polymer to obtain mesophase pitch.

[0013] According to the present disclosure, a method for producing mesophase pitch is provided that can obtain mesophase pitch without using raw materials derived from fossil resources.

[0014] The raw materials used in Example 1 １ 1H-NMR spectrum data of the dehydrogenated product obtained in Example 1. １ 1H-NMR spectrum data. 1H-NMR spectrum data of the dehydrogenated product used in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. 1H-NMR spectrum data of the mesophase pitch obtained in Example 1. １1H-NMR spectrum data. 1H-NMR spectrum data of the dehydrogenated product used in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. 1H-NMR spectrum data of the mesophase pitch obtained in Example 2. １ 1H-NMR spectrum data. MALDI-TOFMS spectrum data of the dehydrogenated product used in Example 3. MALDI-TOFMS spectrum data of the mesophase pitch obtained in Example 3. Image data obtained when the heated mesophase pitch obtained in Example 3 was observed in polarized light using a polarizing microscope. Image data obtained when the heated mesophase pitch obtained in Example 4 was observed in polarized light using a polarizing microscope. １ 1H-NMR spectral data. MALDI-TOFMS spectral data of the dehydrogenated product used in Example 4. MALDI-TOFMS spectral data of the mesophase pitch obtained in Example 4. Image data obtained when the heated mesophase pitch obtained in Example 4 was observed under polarized light using a polarizing microscope. MALDI-TOFMS spectral data of the dehydrogenated product obtained in Example 5. MALDI-TOFMS spectral data of the mesophase pitch obtained in Example 5. Image data obtained when the heated mesophase pitch obtained in Example 5 was observed under polarized light using a polarizing microscope. Results of thermogravimetric analysis of the mesophase pitches obtained in Examples 1 to 5.

[0015] A method for producing mesophase pitch according to one embodiment of the present disclosure includes either a first production method having a first step of preparing a dehydrogenated product of terpenes and a second step of polymerizing the dehydrogenated product to obtain mesophase pitch, or a second production method having a third step of preparing a polymer of terpenes and a fourth step of dehydrogenating the polymer to obtain mesophase pitch. According to the production method of this embodiment (a production method including the first production method or the second production method), mesophase pitch can be obtained without using raw materials derived from fossil resources.

[0016] According to the production method of this embodiment, it is possible to eliminate or reduce the use of raw materials derived from fossil resources when producing mesophase pitch, and even if the supply amount of raw materials derived from fossil resources (e.g., coal-based pitch, petroleum-based pitch) is reduced, there is no problem in producing mesophase pitch. Furthermore, pine resin, which is contained in a wide range of pine wood, including thinned wood, can be used as the terpenes, and by using renewable resources instead of fossil resources, carbon dioxide emissions can be reduced.

[0017] In this specification, "fossil resources" include, for example, coal, petroleum, natural gas, oil shale, oil sands, and other materials that are normally called "fossil fuels."

[0018] In this specification, the term "mesophase," also referred to as "carbonaceous mesophase," refers to the optical anisotropy and the state exhibiting optical anisotropy observed during the carbonization process of organic matter. Mesophases often initially form as spheres and then develop from the spheres into bulk bodies, which are also referred to as mesophase spheres, mesophase globules, mesophase spherulites, mesophase liquid crystals, bulk mesophases, etc., and these are also types of mesophases.

[0019] In this specification, "mesophase pitch" refers to pitch in which the formation of an optically anisotropic structure can be confirmed when the solid obtained by heating the pitch and passing through a molten state is observed under a polarizing microscope. It is presumed that the mesophase pitch exhibits optical anisotropy due to the orientation of the aromatic ring skeleton in the mesophase pitch when melted by heating.

[0020] The mesophase pitch obtained by the manufacturing method of this embodiment exhibits optical anisotropy when heated, similar to conventional mesophase pitch. The mesophase pitch obtained by the manufacturing method of this embodiment can further form a carbonized product, which has excellent properties in terms of high elasticity and thermal conductivity. Therefore, the mesophase pitch obtained by the manufacturing method of this embodiment can be used as a raw material for manufacturing various carbon materials.

[0021] Examples of the carbon material include carbon fibers obtained by spinning, infusibilizing, and carbonizing mesophase pitch; needle coke obtained by pyrolyzing and carbonizing mesophase pitch; carbon electrode materials (e.g., graphite electrode materials, negative electrode materials for lithium ion batteries) or carbon materials for capacitors obtained by graphitizing the needle coke; mesocarbon microbeads obtained by heat-treating mesophase pitch; and binders (e.g., steel binders) obtained by mixing mesophase pitch with other components or by heat-treating mesophase pitch. The mesophase pitch can also be used as is as an impregnated pitch for graphite electrodes.

[0022] First Production Method <<First Step>> In the first step of the first production method, a dehydrogenated terpene is prepared. For example, in the first step, the dehydrogenated terpene may be obtained by dehydrogenating the terpene (subjecting the terpene to a dehydrogenation reaction), or a dehydrogenated terpene that has already been prepared may be obtained. When dehydrogenating terpenes, a dehydrogenated aromatic compound is obtained from terpenes that are non-aromatic (in other words, aliphatic) compounds. On the other hand, a dehydrogenated aromatic compound with a newly generated aromatic moiety is obtained from aromatic terpenes.

[0023] <Terpenes> The terpenes used in the first step are a concept that encompasses terpenes (naturally occurring substances) and their derivatives. Terpenes are also called terpenoids or isoprenoids.

[0024] In this specification, a compound whose structure has been modified is referred to as a "derivative" of the specific compound. Examples of structural modifications include isomerization, hydrogenation, and substitution of one or more hydrogen atoms with groups other than hydrogen atoms. In this specification, unless otherwise specified, the term "group" includes not only an atomic group formed by bonding multiple atoms but also a single atom.

[0025] The terpenes may be either chain terpenes having only a chain structure (linear or branched), or cyclic terpenes (monocyclic or polycyclic) having only a cyclic structure (monocyclic or polycyclic), or having both a chain structure and a cyclic structure (monocyclic terpenes or polycyclic terpenes).There are many non-aromatic compounds that do not have an aromatic ring group among the cyclic terpenes, and the cyclic terpenes may be such non-aromatic compounds, or may be aromatic compounds having an aromatic ring group (for example, dehydroabietic acid).

[0026] The terpenes used in the first step may be one kind or two or more kinds, and when two or more kinds are used, the combination and ratio thereof can be arbitrarily selected according to the purpose. For example, when two or more kinds of terpenes are used, two or more kinds of terpenes may be used without using a terpene derivative, two or more kinds of terpene derivatives may be used without using a terpene, or one or two or more kinds of terpenes and terpene derivatives may be used.

[0027] Examples of terpenes include terpenes contained in products of plants, insects, fungi, bacteria, etc. In terms of easier availability and handling, terpenes contained in products of plants are preferred, terpenes contained in products of pine are more preferred, and terpenes contained in raw pine resin are even more preferred. These terpenes are derived from biomass.

[0028] Terpenes include isoprene units (C ５ ) and compounds synthesized by combining multiple of these. More specifically, hemiterpenes (C ５ ×1=C ５ ), monoterpenes (C ５ ×2=C １０ ), sesquiterpenes (C ５ ×3=C １５ ), diterpenes (C ５ ×4=C ２０ ), sesterterpenes (C ５ ×5=C ２５ ), triterpenes (C ５ ×6=C３０ ), tetraterpene (C ５ ×8=C ４０ ), polyterpenes, etc.

[0029] Hemiterpenes (C ５ Examples of the terpenes include isoprene, isopentanoic acid (also known as isovaleric acid, 3-methylbutanoic acid), and other chain hemiterpenes.

[0030] Monoterpenes (C １０ Examples of the terpenes include chain monoterpenes such as citronellal and geranyl diphosphate; and cyclic terpenes such as limonene, terpinene, phellandrene, terpinolene, menthol, camphor, and pinene.

[0031] Sesquiterpenes (C １５ Examples of the sesquiterpenes include chain sesquiterpenes such as farnesol and farnesyl diphosphate; and cyclic sesquiterpenes such as zingiberene, humulene, cadinene, longifolene, copaene, patchoulol, bisabolene, selinene, caryophyllene, and cedrene.

[0032] Diterpenes (C ２０) include, for example, chain diterpenes such as phytol and geranylgeranyl diphosphate; phytane, prenylbisavorane, labdane, haliman, gunaphalan, cholensane, clerodane, abietane, isetexane, totalane, nagilactone, pimarane, losane, erythroxylan, paraguaran, devadaran, kassane, cleistanthan, isocleistanthan, isocopalane, kaurane, phyllocladane, and biloba. Lido, Ginkgolide, Beyeran, Bilanoban, Atisan, Trachiloban, Herbifulban, Aconitan, Heterathisan, Aphidicoran, Gibberellan, Gibban, Leucotol, Grayanotoxan, Cembrane, Basman, Euniceran, Avestinan, Espheran, Brianan, Laveran, Neodoraberan, Drastan, Ciatan, Espheroan, Vercosan, Neovercosan, Homorecosan, Neohomobercosan, Examples of cyclic diterpenes include san, casban, lathyrane, rhamnophorane, daphnane, tigliane, ingenane, jatrophane, jatropholane, crotophorane, fusicocane, valparan, murinane, espatane, vertisirane, taxane, trinervitane, kempane, amphilectan, cycloamphilectan, adocyan, neoamphilectan, xenicane, xeniaphyllan, bisidan, elemane, prenyleudesmane, prenylgermacrane, prenylcyclogermacrane, loban, kijiktian, prenylaromadendrane, serrulatane, biflorane, decipian, sakuratan, obtusan, esphenoloban, sordaricin, cembrene, dolabradiene, taxinine, kaurene, aconitine, abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, and dehydroabietic acid.

[0033] Sesterterpenes (C ２５ Examples of the sesterterpenes include open-chain sesterterpenes such as geranylfarnesol and geranylfarnesyl diphosphate; and cyclic sesterterpenes such as ophiobolin and gascardic acid.

[0034] Triterpenes (C ３０Examples of the squalene-containing aromatic hydrocarbons include chain sesterterpenes such as squalene and squalene oxide; and cyclic triterpenes such as dammarane, fusidic acid, herbolic acid, gammacerane, hopane, lanostane, lanosterol, cycloartane, cycloartenol, cycloartenone, lupane, betulin, betulinic acid, lupeol, oleanane, β-amyrin, glycyrrhetin, glycyrrhetinic acid, glycyrrhizin, glycyrrhizinic acid, oleanolic acid, oleanolic acid, protostane, ursane, α-amyrin, ursol, and ambreic acid.

[0035] Tetraterpene (C ４０ Examples of the tetraterpenes include chain tetraterpenes such as phytoene; and cyclic tetraterpenes such as carotenoids.

[0036] The terpenes exemplified so far are preferred for use in this embodiment, but they are only a small portion of those that can be used in this embodiment. There are a huge variety of naturally occurring terpenes, and they can all be used in this embodiment. Cyclic terpenes are not limited to their type, and aromatic moieties can be formed relatively easily by dehydrogenation, and these aromatic compounds are also not limited to their type, and the molecular size can be increased relatively easily by polymerization. As described below, chain terpenes can also be cyclized relatively easily, and similarly, aromatic compounds with increased molecular size can be obtained. Thus, in this embodiment, a wide range of terpenes can be used without any particular limitations.

[0037] Examples of sesterterpene derivatives include levopimaric acid, dihydroabietic acid, and tetrahydroabietic acid.

[0038] When a mixture of two or more terpenes is used as the terpenes in the first step, examples of the terpenes include those contained in raw pine resin and those contained in rosin. Examples of the rosin (also known as colophonium or pine resin; the same applies hereinafter) include gum rosin, which is obtained by steam distilling raw pine resin and removing turpentine (also known as turpentine oil; the same applies hereinafter) from the resulting distillate; wood rosin, which is obtained by extracting pine stumps with a solvent and removing turpentine from the resulting extract; and tall rosin, tall oil fatty acids, and tall oil pitch, which are obtained by subjecting pine wood to a decomposition treatment using chemicals under high temperature and high pressure conditions, extracting crude tall oil in the process of extracting pulp fiber, and then fractionating the crude tall oil obtained. Specifically, examples of the terpenes contained in rosin include those contained in gum rosin, wood rosin, tall rosin, tall oil fatty acids, and tall oil pitch. These terpenes are derived from biomass.

[0039] Examples of terpenes contained in gum rosin, wood rosin, and tall rosin include abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, and dehydroabietic acid. Hereinafter, gum rosin, wood rosin, and tall rosin may be collectively abbreviated as "gum rosin, etc." Furthermore, abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, and dehydroabietic acid may be collectively abbreviated as "abietic acid, etc."

[0040] Examples of the terpene derivatives include terpene derivatives contained in polymerized rosin obtained by polymerizing gum rosin or the like; terpene derivatives contained in reinforced rosin obtained by reacting gum rosin or the like with an α,β-unsaturated carboxylic acid and / or anhydride thereof (for example, a reaction product obtained by reacting abietic acid or the like with an α,β-unsaturated carboxylic acid and / or anhydride thereof); terpene derivatives contained in rosin-modified phenolic resin obtained by reacting gum rosin or the like with resole or polyol (for example, a reaction product obtained by reacting abietic acid or the like with resole or polyol); terpene derivatives contained in maleated rosin obtained by reacting gum rosin or the like with maleic acid (for example, a reaction product obtained by reacting abietic acid or the like with maleic acid); Examples of the terpene derivatives include those contained in maleic acid-modified rosin resins obtained by reacting the maleated rosin with a polyol (for example, a reaction product obtained by further reacting a reaction product obtained by reacting abietic acid or the like with maleic acid with a polyol); those contained in ester gums obtained by reacting gum rosin or the like with a polyol (for example, a reaction product obtained by reacting abietic acid or the like with a polyol); those contained in hardened rosins obtained by treating gum rosin or the like with a divalent metal chloride (for example, a divalent metal salt of abietic acid or the like); those contained in rosin alkali soaps obtained by treating gum rosin or the like with an alkaline aqueous solution (for example, an alkali metal salt of abietic acid or the like); and those contained in acrylated rosin obtained by reacting gum rosin or the like with acrylic acid (for example, a reaction product obtained by reacting abietic acid or the like with acrylic acid).

[0041] As explained above, in this embodiment, a wide range of terpenes can be used, and a similarly wide range of terpene derivatives can also be used.

[0042] The terpenes used in the first step are preferably cyclic terpenes, and more preferably polycyclic terpenes (polycyclic terpenes). The mesophase pitch obtained by using these cyclic terpenes exhibits better optical anisotropy.

[0043] Acyclic (non-cyclic) terpenes can be converted into cyclic terpenes by known methods, and in the first step, such cyclic terpenes derived from acyclic terpenes may be dehydrogenated.

[0044] For example, among the chain terpenes, squalene oxide can be converted into a cyclic triterpene by squalene oxide cyclase (see Non-Patent Document 3). For example, chain terpenes can be cyclized using a catalyst such as a metal chloride (see Non-Patent Document 4).

[0045] The number of carbon atoms of the terpenes used in the first step is preferably 10 or more, and may be, for example, any of 15 or more, 20 or more, 25 or more, and 30 or more. Many of these terpenes are cyclic, and the mesophase pitch obtained by using these terpenes further improves the optical anisotropy exhibited by the mesophase.

[0046] The terpenes used in the first step are preferably one or more selected from Group 1 consisting of abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid, levopimaric acid, dihydroabietic acid, and tetrahydroabietic acid, and one or more terpenes selected from Group 2 consisting of raw pine resin, tall rosin, gum rosin, wood rosin, and tall oil pitch. More preferably, the terpenes are either terpenes selected from Group 1 or terpenes selected from Group 2. These terpenes are easily available, and the mesophase pitch obtained using these terpenes further improves the optical anisotropy of the mesophase. The structural formulas of some of these terpenes are shown below.

[0047]

[0048] <Dehydrogenation Conditions> [Dehydrogenation Catalyst] The dehydrogenation of terpenes is preferably carried out using a catalyst (dehydrogenation catalyst). Examples of the dehydrogenation catalyst include noble metal catalysts such as platinum (Pt) and palladium (Pd); iron oxide (FeO); ２ O ３ ) catalyst, copper oxide-chromium oxide (CuO-Cr ２ O ３ )-based catalysts; basic oxides; alumina (aluminum oxide), etc. ２ O ３ The iron oxide (Fe)-based catalyst is a catalyst containing at least iron oxide. ２ O ３ ) and potassium oxide (K ２ O), cerium oxide (CeO ２ ), molybdenum oxide (MoO ２ ), tungsten oxide (WO ２ ), magnesium oxide (MgO), chromium oxide (Cr ２ O ３ and one or more catalysts selected from the group consisting of copper oxide (CuO).

[0049] The dehydrogenation catalyst may be supported on a carrier such as carbon (activated carbon).

[0050] The dehydrogenation catalyst is preferably a catalyst that does not contain either or both sulfur and nitrogen atoms, and more preferably a catalyst that does not contain either sulfur or nitrogen atoms. In mesophase pitch derived from fossil resources such as coal-based pitch and petroleum-based pitch, the sulfur and nitrogen contained in the fossil resources tend to be clearly detected. When such mesophase pitch is used to produce a carbon material, the sulfur and nitrogen inevitably cause the generation of harmful gases such as nitrogen oxides and hydrogen sulfide. Furthermore, when mesophase pitch is graphitized, sulfur and nitrogen can cause abnormal thermal expansion of graphite and the resulting cracks. Therefore, it is preferable that the sulfur and nitrogen contents of mesophase pitch be low. In contrast, in this embodiment, it is relatively easy to select terpenes, the main raw material, that do not contain either sulfur or nitrogen atoms in their structure. In this case, by using a dehydrogenation catalyst, the secondary raw material, that does not contain at least one of sulfur and nitrogen atoms, the sulfur or nitrogen content of mesophase pitch can be more easily reduced than in mesophase pitch derived from fossil resources.

[0051] The dehydrogenation catalyst used in the first step may be one kind or two or more kinds, and when two or more kinds are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose. Usually, it is sufficient to use only one kind of dehydrogenation catalyst.

[0052] The amount of the dehydrogenation catalyst used is not particularly limited, but is preferably 0.1 to 1 part by mass, more preferably 0.15 to 0.85 parts by mass, and even more preferably 0.2 to 0.7 parts by mass, relative to 100 parts by mass of terpenes. When the amount of the dehydrogenation catalyst used is equal to or greater than the lower limit, the effect of using the dehydrogenation catalyst is more pronounced. When the amount of the dehydrogenation catalyst used is equal to or less than the upper limit, excessive use of the dehydrogenation catalyst is suppressed.

[0053] The atmosphere in which the dehydrogenation of terpenes is carried out is not particularly limited, but it is preferable to carry out the dehydrogenation in an atmosphere of an inert gas such as nitrogen gas, helium gas or argon gas, or water vapor.

[0054] The temperature (reaction temperature) and time (reaction time) when dehydrogenating terpenes are not particularly limited, but the reaction is preferably carried out at 300 to 500°C for 0.5 to 5 hours, more preferably at 340 to 480°C for 0.5 to 3.5 hours, and even more preferably at 380 to 460°C for 0.5 to 2 hours. When the reaction temperature and reaction time are at or above the lower limit values, the dehydrogenation of terpenes proceeds more quickly. When the reaction temperature and reaction time are at or below the upper limit values, these conditions can be avoided from becoming excessive.

[0055] The rate of temperature rise of the terpenes when dehydrogenating the terpenes is not particularly limited, but is preferably 3 to 17°C / min, more preferably 5 to 15°C / min, and even more preferably 7 to 13°C / min.

[0056] [Other Dehydrogenation Feedstocks] In Step 1, other dehydrogenation feedstocks than terpenes may or may not be used to produce a polymerizable dehydrogenated product in Step 2. Examples of the other dehydrogenation feedstocks include pitches derived from fossil resources, such as coal-based pitch and petroleum-based pitch.

[0057] In the first step, the ratio of the amount of terpenes used (parts by mass) to the total amount of the terpenes used (parts by mass) and the amount of other dehydrogenation raw materials used (parts by mass) ([amount of terpenes used (parts by mass) in the first step] / ([amount of terpenes used (parts by mass) in the first step] + [amount of other dehydrogenation raw materials used (parts by mass) in the first step]) × 100) is preferably 90% by mass or more, more preferably 93% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the effect of this embodiment, that raw materials derived from fossil resources are not required, becomes more pronounced. On the other hand, when this ratio is 100% by mass or less.

[0058] [Other Conditions] Dehydrogenation of terpenes is preferably carried out under pressurized conditions, since dehydrogenation proceeds more rapidly. In this case, the pressure when dehydrogenating terpenes is preferably 1 to 5 MPa, more preferably 1.5 to 4.5 MPa, and even more preferably 2 to 4 MPa. When the pressure is equal to or greater than the lower limit, dehydrogenation of terpenes proceeds more rapidly. When the pressure is equal to or less than the upper limit, excessive pressure is avoided, and further, the versatility of dehydrogenating terpenes is increased.

[0059] The dehydrogenation of terpenes is preferably carried out while stirring or agitating the raw materials, i.e., the terpenes, and optionally the dehydrogenation catalyst and optionally the other raw materials for dehydrogenation, so that the dehydrogenation of terpenes proceeds more rapidly.

[0060] The dehydrogenated product (aromatic compound) obtained by dehydrogenation of terpenes (dehydrogenation reaction) may be obtained, for example, by removing it directly from the reaction vessel, or by adding a solvent to the reaction vessel to prepare a liquid (for example, a solution) containing the dehydrogenated product, removing this liquid from the reaction vessel, and then drying it. Examples of the solvent include dichloromethane (CH ２ Cl ２ ), chloroform (CHCl ３ ) and other halogenated hydrocarbons.

[0061] In this specification, unless otherwise specified, the term "solvent" is a concept that encompasses both a component that is liquid at room temperature and that dissolves a solute, and a component that is liquid at room temperature and that functions as a dispersion medium for dispersing a dispersoid. In this specification, "room temperature" means a temperature that is not particularly cooled or heated, that is, an ordinary temperature, and examples thereof include a temperature of 15 to 25°C.

[0062] The fact that dehydrogenated terpenes are obtained in the first step can be confirmed by a known method. For example, since dehydrogenated terpenes are aromatic compounds, when the terpenes are non-aromatic compounds, proton nuclear magnetic resonance spectroscopy ( １When the dehydrogenated product is analyzed by H-NMR (Proton Nuclear Magnetic Resonance), a peak of aromatic hydrogen that cannot be observed when terpenes are analyzed is newly observed, and this confirms that a dehydrogenated product has been obtained. On the other hand, when terpenes are aromatic compounds, １ When the dehydrogenated product is analyzed by H-NMR, the peak intensity of aromatic hydrogen differs from that observed when the terpenes are analyzed, or a peak of aromatic hydrogen that is not observed when the terpenes are analyzed is newly observed, thereby confirming that the dehydrogenated product has been obtained. １ By combining other analytical methods with H-NMR and confirming the results of those analyses, it is possible to more accurately confirm that a dehydrogenated product has been obtained.

[0063] <<Second Step>> In the second step of the first production method, the dehydrogenated product prepared in the first step is polymerized (the dehydrogenated product is polymerized) to obtain mesophase pitch. According to the second step, a polymer with an increased molecular weight is obtained from the dehydrogenated product. This polymer (mesophase pitch) forms a mesophase exhibiting optical anisotropy by heat treatment.

[0064] <Polymerization Conditions> [Polymerization Catalyst] The polymerization of the dehydrogenated product is preferably carried out using a catalyst (polymerization catalyst). The polymerization catalyst may be a known polymerization initiator. Examples of the polymerization catalyst include a cationic polymerization catalyst, an anionic polymerization catalyst, a coordination polymerization catalyst, a solid acid catalyst, and a protonic acid (also known as a Bronsted acid).

[0065] Among the polymerization catalysts, the catalyst for cationic polymerization is, for example, hydrogen iodide / iodine (HI / I ２ ), hydrogen iodide / zinc iodide (HI / ZnI ２ ), hydrogen iodide / zinc bromide (HI / ZnBr ２ ), hydrogen iodide / zinc chloride (HI / ZnCl ２ hydrogen iodide catalysts such as iron(III) chloride (FeCl ３ ), aluminum chloride (AlCl ３ ), titanium tetrachloride (also known as titanium(IV) chloride, TiCl４ ) and other metal chlorides.

[0066] Among the polymerization catalysts, examples of the catalyst for anionic polymerization include organic alkali metal compounds such as alkyllithium (e.g., butyllithium); organic magnesium halides (Grignard reagents); alkali metals such as sodium and lithium; metal alkoxides such as lithium alkoxide and sodium alkoxide; trialkylaluminum; and dialkylzinc.

[0067] Among the polymerization catalysts, examples of the catalyst for coordination polymerization include transition metal complexes such as Ziegler-Natta catalysts, etc. Among the polymerization catalysts, examples of the solid acid catalyst include zeolite, activated alumina (porous aluminum oxide), etc.

[0068] Among the polymerization catalysts, the protonic acid is, for example, sulfuric acid (H ２ SO ４ ), hydrogen chloride (HCl), hydrogen fluoride (HF), and other inorganic acids; trifluoroacetic acid (CF ３ COOH), trichloroacetic acid (CCl ３ Halogenated carboxylic acids such as trifluoromethanesulfonic acid (CF ３ SO ３ Halogenated sulfonic acids such as perchloric acid (HClO ４ ) and the like.

[0069] The polymerization catalyst is preferably a catalyst that does not contain either or both of sulfur atoms and nitrogen atoms, and more preferably a catalyst that does not contain either sulfur atoms or nitrogen atoms. The reason for this is the same as in the case of the dehydrogenation catalyst described above. That is, to reduce the sulfur or nitrogen content in the mesophase pitch. On the other hand, the polymerization catalyst is preferably one that is liquid at room temperature. Such a polymerization catalyst can be easily removed from the mesophase pitch by washing the mesophase pitch with a solvent, and thereby the sulfur or nitrogen content in the mesophase pitch can be more easily reduced than in the case of mesophase pitch derived from fossil resources.

[0070] The polymerization catalyst used in the second step may be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose. Usually, it is sufficient to use only one type of polymerization catalyst.

[0071] The amount of the polymerization catalyst used is not particularly limited, but is preferably 10 to 75 parts by mass, more preferably 15 to 70 parts by mass, and even more preferably 18 to 65 parts by mass, per 100 parts by mass of the dehydrogenated product. When the amount of the polymerization catalyst used is equal to or greater than the lower limit, the effect of using the polymerization catalyst is more pronounced. When the amount of the polymerization catalyst used is equal to or less than the upper limit, excessive use of the polymerization catalyst is suppressed.

[0072] [Oxidizing Agent] The polymerization of the dehydrogenation product may be carried out using an oxidizing agent that does not fall under the category of a polymerization catalyst. This may increase the amount of polymer produced. Examples of the oxidizing agent include 2,3-dichloro-5,6-dicyano-p-benzoquinone (also known as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, DDQ).

[0073] The oxidizing agent preferably does not contain either or both of sulfur atoms and nitrogen atoms, and more preferably does not contain either sulfur atoms or nitrogen atoms. The reason for this is the same as in the case of the dehydrogenation catalyst described above: that is, to reduce the sulfur or nitrogen content in the mesophase pitch.

[0074] The oxidizing agent used in the second step may be one kind or two or more kinds, and when two or more kinds are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose. Usually, it is sufficient to use only one kind of oxidizing agent.

[0075] The amount of oxidizing agent used is not particularly limited, but is preferably 30 to 120 parts by mass, more preferably 35 to 110 parts by mass, and even more preferably 40 to 105 parts by mass, relative to 100 parts by mass of the dehydrogenated product. When the amount of oxidizing agent used is equal to or greater than the lower limit, the effect of using the oxidizing agent is more pronounced. When the amount of oxidizing agent used is equal to or less than the upper limit, excessive use of the oxidizing agent is suppressed.

[0076] [Solvent] The polymerization of the dehydrogenated product is preferably carried out in a solvent. By doing so, raw materials such as the dehydrogenated product can be present with high uniformity before the reaction, and the polymerized product can be produced more quickly. The solvent is preferably an organic solvent. Examples of the organic solvent include dichloromethane (CH ２ Cl ２ ), chloroform (CHCl ３ ) and other halogenated hydrocarbons.

[0077] The solvent used in the second step may be one type only, or two or more types. When two or more types are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

[0078] The amount of solvent used is not particularly limited, but is preferably 80 to 300 mL, more preferably 90 to 280 mL, and even more preferably 100 to 260 mL per gram of dehydrogenated product. When the amount of solvent used is equal to or greater than the lower limit, the effect of using the solvent is more pronounced. When the amount of solvent used is equal to or less than the upper limit, excessive use of the solvent is suppressed.

[0079] [Other Conditions] The atmosphere in which the dehydrogenation product is polymerized is not particularly limited. For example, the polymerization of the dehydrogenation product can be carried out under an atmosphere of an inert gas such as nitrogen gas, helium gas, or argon gas; an oxidizing gas such as oxygen gas, ozone gas, nitrous oxide gas, nitric oxide gas, nitrogen dioxide gas, fluorine gas, chlorine gas, chlorine dioxide gas, nitrogen trifluoride gas, chlorine trifluoride gas, silicon tetrachloride gas, oxygen difluoride gas, or perchloryl fluoride (also known as chlorine trifluoride) gas; or air.

[0080] The temperature at which the dehydrogenation product is polymerized (the reaction temperature is not particularly limited, but is preferably −10 to 30° C., more preferably −5 to 20° C., and even more preferably 0 to 10° C. When the reaction temperature is equal to or higher than the lower limit, the polymerization of the dehydrogenation product proceeds more rapidly. When the reaction temperature is equal to or lower than the upper limit, the amount of by-products can be reduced.

[0081] The time (reaction time) for polymerizing the dehydrogenated product is not particularly limited, but is preferably 1 to 12 hours, more preferably 1.5 to 9 hours, and even more preferably 2 to 6 hours. When the reaction time is equal to or greater than the lower limit, the amount of polymer produced increases. When the reaction time is equal to or less than the upper limit, an excessively long reaction time can be avoided. These reaction times are particularly suitable when the reaction temperature is any of the above.

[0082] The polymerization of the dehydrogenated product may be carried out under normal pressure, elevated pressure or reduced pressure, but is preferably carried out under normal pressure in that the second step is simpler.

[0083] The polymer (mesophase pitch) obtained in the second step can be extracted by a known method. For example, when the second step is performed using a solvent, if mesophase pitch precipitates as an insoluble component in the reaction solution obtained after the reaction, the mesophase pitch can be extracted by solid-liquid separation, such as filtering the reaction solution. If mesophase pitch does not precipitate in the reaction solution obtained after the reaction, or if it precipitates but in a small amount, the temperature of the reaction solution can be lowered with or without stirring, or the reaction solution can be left for a certain period of time without lowering the temperature, with or without stirring, to increase the amount of mesophase pitch precipitated in the reaction solution, and the mesophase pitch can be extracted by solid-liquid separation, such as filtering the reaction solution.

[0084] The extracted mesophase pitch is preferably further washed with a solvent. The solvent used for washing is not particularly limited. Preferred washing solvents include, for example, alcohols such as methanol, ethanol, and 2-propanol (also known as propan-2-ol).

[0085] The mesophase pitch after solid-liquid separation is preferably dried. The mesophase pitch may be dried at room temperature or by heating, and may be dried under normal pressure or reduced pressure (vacuum drying).

[0086] The obtained mesophase pitch is a polycyclic aromatic compound having at least an aromatic cyclic group and a structure in which aromatic rings, aliphatic rings, or an aromatic ring and an aliphatic ring are fused to each other. In the mesophase pitch, the total number of aromatic rings constituting one fused ring structure is preferably 10 or more. By using such a mesophase pitch, the optical anisotropy exhibited by the mesophase is improved.

[0087] The fact that the polymer (mesophase pitch) was obtained from the dehydrogenated product in the second step can be confirmed by a known method. For example, since mesophase pitch has a larger molecular size than the dehydrogenated product, which is its raw material, it can be confirmed by mass spectrometry (MS) that the molecular weight of the polymer is larger than the molecular weight of the dehydrogenated product, thereby confirming that the obtained polymer is mesophase pitch. Various mass spectrometry methods can be used, and a preferred example is matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOFMS, MALDI: Matrix Assisted Laser Desorption / Ionization, TOFMS: Time of Flight Mass Spectrometry).

[0088] Furthermore, by combining mass spectrometry with other analytical methods such as elemental analysis and confirming the results of those analyses, it is possible to more accurately confirm that mesophase pitch has been obtained.

[0089] <<Other Steps (1)>> The first production method may or may not include other steps (1) that do not fall under the categories of steps 1 and 2, in addition to steps 1 and 2, as long as the effects of the present disclosure are not impaired. The type, number, and timing of the other steps (1) can be arbitrarily set depending on the purpose and are not particularly limited.

[0090] Second Production Method <<Third Step>> In the third step of the second production method, a polymer of terpenes is prepared. For example, in the third step, the polymer of terpenes may be obtained by polymerizing terpenes (polymerizing terpenes), or a polymer of terpenes that has already been prepared may be obtained. When terpenes are polymerized, a polymer with an increased molecular weight is obtained from the terpenes. The polymer may be either a non-aromatic compound or an aromatic compound.

[0091] <Terpenes> The terpenes used in the third step are the same as those used in the first step. For example, the terpenes used in the third step are preferably those contained in plant products, more preferably those contained in pine products, and even more preferably those contained in raw pine resin, in terms of easier availability and handling. For example, the terpenes used in the third step are more preferably cyclic terpenes, and even more preferably polycyclic terpenes (polycyclic terpenes). The mesophase pitch obtained by using these cyclic terpenes improves the optical anisotropy exhibited by the mesophase. For example, the terpenes used in Step 3 are preferably one or more terpenes selected from Group 1 consisting of abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid, levopimaric acid, dihydroabietic acid, and tetrahydroabietic acid, and one or more terpenes selected from Group 2 consisting of raw pine resin, tall rosin, gum rosin, wood rosin, and tall oil pitch. These terpenes are easily available, and the mesophase pitch obtained using these terpenes further improves the optical anisotropy of the mesophase.

[0092] The cyclic terpenes and chain terpenes are not limited to their types, and their molecular size can be increased relatively easily by polymerization. Furthermore, the polymers are not limited to their types, and aromatic moieties can be formed relatively easily by dehydrogenation. Therefore, in this embodiment, a wide range of terpenes can be used without any particular limitations.

[0093] The manner in which the terpenes are used in the third step is the same as the manner in which the dehydrogenated product is used in the second step, so further detailed description of the terpenes used in the third step will be omitted.

[0094] <Polymerization Conditions> The third step may be the same as the second step, except that terpenes are used as the object of polymerization (raw material) instead of dehydrogenated terpenes. More specifically, the conditions are as follows.

[0095] [Polymerization catalyst] The polymerization of the terpenes is preferably carried out using a catalyst (polymerization catalyst) for the same reasons as in Step 2. The polymerization catalyst used in Step 3, the preferred polymerization catalyst, and the mode of use of the polymerization catalyst are the same as those in Step 2 described above, and detailed explanations thereof will be omitted.

[0096] [Oxidizing Agent] The polymerization of the terpenes may be carried out using an oxidizing agent that does not fall under the category of a polymerization catalyst for the same reasons as in Step 2. The oxidizing agent used in Step 3, the preferred oxidizing agent, and the mode of use of the oxidizing agent are the same as those in Step 2 described above, and detailed description thereof will be omitted.

[0097] [Solvent] The polymerization of the terpenes is preferably carried out in a solvent for the same reasons as in Step 2. The solvent, preferred solvent, and mode of use of the solvent used in Step 3 are the same as those in Step 2 described above, and detailed description thereof will be omitted.

[0098] [Other Polymerization Raw Materials] In Step 3, other polymerization raw materials than terpenes may or may not be used to produce a polymer that can be dehydrogenated in Step 4. Examples of the other polymerization raw materials include pitches derived from fossil resources, such as coal-based pitch and petroleum-based pitch.

[0099] In the third step, the ratio of the amount (parts by mass) of terpenes used to the total amount (parts by mass) of terpenes used and the amount (parts by mass) of other polymerization raw materials used ([amount (parts by mass) of terpenes used in the third step] / ([amount (parts by mass) of terpenes used in the third step] + [amount (parts by mass) of other polymerization raw materials used in the third step]) × 100) is preferably 90% by mass or more, more preferably 93% by mass or more, and may be, for example, any of 95% by mass or more, 97% by mass or more, and 99% by mass or more. When this ratio is equal to or greater than the lower limit, the effect of this embodiment, that raw materials derived from fossil resources are not required, becomes more pronounced. On the other hand, when this ratio is 100% by mass or less.

[0100] [Other Conditions] In the third step, the atmosphere, temperature (reaction temperature), time (reaction time), and pressure when polymerizing the terpenes may be the same as the atmosphere, temperature (reaction temperature), time (reaction time), and pressure when polymerizing the dehydrogenated product in the second step.

[0101] The polymer (non-aromatic compound) obtained by the polymerization (polymerization reaction) of terpenes can be isolated by known methods. For example, when the third step is carried out using a solvent, if the polymer precipitates as an insoluble component in the reaction solution obtained after the reaction, the polymer can be isolated by solid-liquid separation, such as filtering the reaction solution. If the polymer does not precipitate in the reaction solution obtained after the reaction, or if the amount of precipitate is small even if it does, the temperature of the reaction solution can be lowered with or without stirring, or the reaction solution can be left for a certain period of time without lowering the temperature, with or without stirring, to increase the amount of polymer precipitated in the reaction solution, and the polymer can be isolated by solid-liquid separation, such as filtering the reaction solution. When the third step is carried out using a solvent, the concentrate obtained by distilling off the solvent under reduced pressure, or the reaction solution without distilling off the solvent under reduced pressure, may be used in the next step. When the third step is carried out using a solvent, if the polymer does not precipitate in the reaction solution obtained after the reaction, the polymer may be isolated from the reaction solution by various chromatography methods.

[0102] It can be confirmed by a known method that the polymer has been obtained from the terpenes in the third step. For example, since the molecular size of the polymer is larger than that of the raw material terpenes, it can be confirmed that the obtained product is a polymer by mass spectrometry, as in the second step, and further by combining with other analytical methods as necessary.

[0103] <<Fourth Step>> In the fourth step of the second production method, the polymer prepared in the third step is dehydrogenated (the polymer is subjected to a dehydrogenation reaction) to obtain mesophase pitch. According to the fourth step, a dehydrogenated product, which is an aromatic compound, is obtained from the polymer. This dehydrogenated product (mesophase pitch) forms a mesophase exhibiting optical anisotropy by heat treatment.

[0104] <Dehydrogenation Conditions> The fourth step may be the same as the first step, except that a polymer of terpenes is used as the object (raw material) of dehydrogenation instead of terpenes. More specifically, the conditions are as follows.

[0105] [Dehydrogenation catalyst] The dehydrogenation of the polymer is preferably carried out using a catalyst (dehydrogenation catalyst) for the same reasons as in Step 1. The dehydrogenation catalyst used in Step 4, the preferred dehydrogenation catalyst, and the mode of use of the dehydrogenation catalyst are the same as those in Step 1 described above, and detailed description thereof will be omitted.

[0106] [Other Conditions] In the fourth step, the conditions for dehydrogenating the polymer (atmosphere, rate of temperature rise, temperature (reaction temperature), time (reaction time), pressure, and method of agitating the raw materials) may be the same as the conditions for dehydrogenating the terpenes in the first step.

[0107] The dehydrogenated product (aromatic compound, mesophase pitch) obtained in the fourth step may be obtained, for example, by removing it directly from the reaction vessel, or by adding a solvent to the reaction vessel to prepare a liquid containing mesophase pitch, removing this liquid from the reaction vessel, and then filtering the liquid, thereby obtaining the dehydrogenated product. Examples of the solvent include dichloromethane (CH ２ Cl ２ ), chloroform (CHCl ３) and other halogenated hydrocarbons.

[0108] The extracted mesophase pitch is preferably further washed with a solvent. The solvent used for washing is not particularly limited. Preferred washing solvents include, for example, alcohols such as methanol, ethanol, and 2-propanol (also known as propan-2-ol).

[0109] The mesophase pitch after solid-liquid separation is preferably dried. The mesophase pitch may be dried at room temperature or by heating, and may be dried under normal pressure or reduced pressure (vacuum drying).

[0110] It can be confirmed by a known method that the dehydrogenated product (mesophase pitch) is obtained from the polymer in the fourth step. For example, since the dehydrogenated product of the polymer is an aromatic compound, １ When the dehydrogenated product is analyzed by H-NMR, a peak of aromatic hydrogen that is not observed when the polymer is analyzed is newly observed, or the peak intensity of aromatic hydrogen is different from that observed when the polymer is analyzed, and this confirms that the dehydrogenated product has been obtained. １ By combining other analytical methods with H-NMR and confirming the results of those analyses, it is possible to more accurately confirm that a dehydrogenated product has been obtained.

[0111] <<Other Steps (2)>> The second production method may or may not include other steps (2) that do not fall under the categories of steps 3 and 4, in addition to steps 3 and 4, as long as the effects of the present disclosure are not impaired. The type, number, and timing of the other steps (2) can be arbitrarily set depending on the purpose and are not particularly limited.

[0112] <Step 5> A preferred example of the other step (2) is Step 5, which involves polymerizing the dehydrogenated product obtained in Step 4 (polymerizing the dehydrogenated product). By performing Step 5, a polymer with an increased molecular weight can be obtained from the dehydrogenated product (mesophase pitch) obtained in Step 4, which has an increased molecular weight. This polymer (mesophase pitch) also forms a mesophase exhibiting optical anisotropy by heat treatment.

[0113] The fifth step may be the same as the second step, except that the dehydrogenated product obtained in the fourth step is used as the target of polymerization instead of the dehydrogenated product prepared in the first step. For example, as follows. The manner of use of the dehydrogenated product in the fifth step is the same as the manner of use of the dehydrogenated product in the second step. The polymerization conditions in the fifth step may be the same as those in the second step, except that the dehydrogenated product obtained in the fourth step is used as the target of polymerization (raw material) instead of the dehydrogenated product prepared in the first step.

[0114] The polymer (mesophase pitch) obtained in the fifth step can be extracted in the same manner as in the case of the polymer obtained in the second step.

[0115] The fact that a polymer was obtained from the dehydrogenated product in the fifth step (that is, the molecular weight of the mesophase pitch increased) can be confirmed by the same method as in the second step.

[0116] ◇Method of Manufacturing Carbon Fiber A method of manufacturing carbon fiber according to an embodiment of the present disclosure is a method of manufacturing carbon fiber by obtaining mesophase pitch by the method of manufacturing mesophase pitch according to the embodiment of the present disclosure described above, and then spinning, infusibilizing, and carbonizing the mesophase pitch to obtain carbon fiber. The method of manufacturing carbon fiber according to the present embodiment is the same as a conventional method of manufacturing carbon fiber, except that the method of manufacturing mesophase pitch according to the embodiment described above is used instead of the conventional manufacturing method. Carbon fiber obtained by the manufacturing method according to the present embodiment is expected to have elasticity and thermal conductivity equivalent to or greater than that of carbon fiber obtained using raw materials other than mesophase pitch. After obtaining carbon fiber by the manufacturing method according to the present embodiment, graphitization of the carbon fiber results in graphite fiber. Graphite fiber obtained by this manufacturing method is also expected to have elasticity and thermal conductivity equivalent to or greater than that of graphite fiber obtained using raw materials other than mesophase pitch.

[0117] ◇Needle Coke Manufacturing Method The needle coke manufacturing method according to an embodiment of the present disclosure is a manufacturing method in which mesophase pitch is obtained by the mesophase pitch manufacturing method according to the embodiment of the present disclosure described above, and then the mesophase pitch is pyrolyzed (coked) and carbonized to obtain needle coke. The needle coke manufacturing method according to this embodiment is the same as a conventional needle coke manufacturing method, except that the manufacturing method according to the embodiment of the present disclosure described above is used instead of the conventional manufacturing method for mesophase pitch. The needle coke obtained by the manufacturing method according to this embodiment is expected to have hot strength and low thermal expansion coefficient properties equivalent to or better than those of needle coke obtained using mesophase pitch produced from fossil resources as a raw material.

[0118] Binder Manufacturing Method A binder manufacturing method according to an embodiment of the present disclosure is a manufacturing method in which mesophase pitch is obtained by the mesophase pitch manufacturing method according to the embodiment of the present disclosure described above, and then the mesophase pitch is mixed with components other than the mesophase pitch or heat-treated to obtain a binder with a different softening point or carbonization yield. The needle coke manufacturing method of this embodiment is the same as conventional binder manufacturing methods, except that the manufacturing method according to the embodiment of the present disclosure described above is used instead of the conventional manufacturing method for mesophase pitch. The binder obtained by the manufacturing method of this embodiment is expected to have thermal conductivity equivalent to or greater than that of binders obtained using raw materials other than mesophase pitch.

[0119] ◇Method for producing mesocarbon microbeads A method for producing mesocarbon microbeads according to an embodiment of the present disclosure is a method for producing mesocarbon microbeads by obtaining mesophase pitch by the method for producing mesophase pitch according to the embodiment of the present disclosure described above, and then heat-treating the mesophase pitch to obtain mesocarbon microbeads. The method for producing mesocarbon microbeads according to this embodiment is the same as a conventional method for producing mesocarbon microbeads, except that the method for producing mesophase pitch according to the embodiment of the present disclosure described above is used instead of the conventional method for producing mesophase pitch. The mesocarbon microbeads obtained by the production method according to this embodiment are expected to have electrical conductivity and thermal conductivity equivalent to or greater than those of mesocarbon microbeads obtained using mesophase pitch produced from fossil resources as a raw material.

[0120] ◇Method for manufacturing a carbon electrode material A method for manufacturing a carbon electrode material according to an embodiment of the present disclosure is a method for manufacturing a carbon electrode material by obtaining needle coke by the needle coke manufacturing method according to the embodiment of the present disclosure described above, and then using the needle coke to obtain a carbon electrode material. The method for manufacturing a carbon electrode material according to this embodiment is the same as a conventional method for manufacturing a carbon electrode material, except that the manufacturing method according to the embodiment of the present disclosure described above is used as the needle coke manufacturing method instead of the conventional manufacturing method. The carbon electrode material obtained by the manufacturing method according to this embodiment is expected to have electrical conductivity equivalent to or greater than that of carbon electrode materials obtained using raw materials other than mesophase pitch.

[0121] Examples of the Present Disclosure Key points understood from the above disclosure are exemplified as follows: [1] A method for producing mesophase pitch, comprising: a first production method including a first step of preparing a dehydrogenated product of terpenes and a second step of polymerizing the dehydrogenated product to obtain mesophase pitch; or a second production method including a third step of preparing a polymer of terpenes and a fourth step of dehydrogenating the polymer to obtain mesophase pitch. [2] The method for producing mesophase pitch according to [1], wherein the terpenes are one or more terpenes selected from a first group consisting of abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid, levopimaric acid, dihydroabietic acid, and tetrahydroabietic acid; or one or more terpenes contained in one or more terpenes selected from a second group consisting of raw pine resin, tall rosin, gum rosin, wood rosin, and tall oil pitch.

[0122] [3] A method for producing carbon fibers, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to [1] or [2], and then spinning, infusibilizing, and carbonizing the mesophase pitch to obtain carbon fibers. [4] A method for producing needle coke, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to [1] or [2], and then pyrolyzing and carbonizing the mesophase pitch to obtain needle coke. [5] A method for producing binders, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to [1] or [2], and then mixing the mesophase pitch with a component other than the mesophase pitch or heat-treating the mesophase pitch to obtain binders having different softening points or carbonization yields. [6] A method for producing mesocarbon microbeads, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to [1] or [2], and then heat-treating the mesophase pitch to obtain mesocarbon microbeads. [7] A method for producing a carbon electrode material, comprising obtaining needle coke by the method for producing needle coke according to [4], and then using the needle coke to produce a carbon electrode material.

[0123] The present disclosure will be described in more detail below with reference to specific examples, although the present disclosure is not limited to the examples shown below.

[0124] <<Production of Mesophase Pitch (First Production Method) and Evaluation (Examples 1 to 4)>> [Example 1] Abietic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diterpene) (1 g) and palladium-activated carbon (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Pd content 10% by mass, dehydrogenation catalyst) (0.025 g) were sealed in an autoclave (25 mL). The gas in the autoclave was replaced with nitrogen gas by reducing the pressure inside the autoclave and then introducing nitrogen gas, a total of five times. The temperature inside the autoclave was set to room temperature (20°C), the pressure was set to 0.8 Pa, and the temperature inside the autoclave was increased to 420°C at a heating rate of 10°C / min using a mantle heater. The mixture was then heated at 420°C for 1 hour to dehydrogenate the abietic acid. During this time, the autoclave and mantle heater were placed on a shaker and shaken horizontally at 95 rpm. The pressure inside the autoclave during the reaction was adjusted to within the range of 2.7 to 3.6 MPa (Step 1).

[0125] Next, the mantle heater was removed from the autoclave, and the autoclave was allowed to cool until its internal temperature reached 40°C or below. Finally, the autoclave was degassed. Dichloromethane was then charged into the autoclave, and the reaction product was removed as a dichloromethane solution. The entire reaction product solution was placed in a recovery flask, and the dichloromethane was removed by vacuum concentration using an evaporator. The reaction product after dichloromethane removal was vacuum dried to obtain a solid (0.77 g).

[0126] The obtained solid (dehydrogenated product) and abietic acid (raw material) were each １ H-NMR (500MHz, CDCl ３The obtained spectral data of the raw material is shown in FIG. 1A, and the spectral data of the dehydrogenated product is shown in FIG. 1B. As shown in FIG. 1B, a new peak of aromatic hydrogen was observed in the spectral data of the dehydrogenated product, confirming that the dehydrogenated product of abietic acid was indeed obtained in the first step.

[0127] The solid obtained above (0.211 g) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ, oxidizing agent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.097 g) were dissolved in dichloromethane (25 mL), and the resulting solution was placed in a three-neck flask along with a stirrer. With the three-neck flask immersed in ice water, the mixture in the three-neck flask was stirred using a magnetic stirrer, and the gas in the three-neck flask was replaced with nitrogen gas. Furthermore, trifluoromethanesulfonic acid (polymerization catalyst, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (0.025 mL) was added dropwise to the solution in the three-neck flask. The mixture in the three-neck flask was then stirred for 3 hours while remaining cooled (at approximately 0°C) (Step 2). Next, methanol (300 mL) was added to the three-neck flask, and the mixture was left to stand for approximately 1 hour to precipitate a solid. The liquid containing the solid was subjected to suction filtration using a membrane filter to separate the solid into liquid and solid, and the solid on the filter was washed with methanol and vacuum dried to obtain a polymer (mesophase pitch) (0.025 g).

[0128] The obtained mesophase pitch and the solid (dehydrogenated product) were each analyzed by MALDI-TOFMS (matrix: 2,5-dihydroxybenzoic acid). The spectral data obtained for the dehydrogenated product is shown in FIG. 2A, and the spectral data for the mesophase pitch is shown in FIG. 2B. As shown in FIG. 2B, the spectral data for the mesophase pitch showed an increase in molecular weight compared to the dehydrogenated product, indicating that the desired mesophase pitch, a polymer of the dehydrogenated product, was indeed obtained by the second step.

[0129] Furthermore, the obtained mesophase pitch was subjected to CHNS elemental analysis, and the results are shown in Table 1 together with literature values ​​for petroleum-based mesophase pitch obtained from petroleum-based pitch and literature values ​​for coal-based mesophase pitch obtained from coal-based pitch.

[0130] <Confirmation of Optical Anisotropy> The mesophase pitch obtained above was placed on the top surface of a flat glass plate, heated to 380°C under a nitrogen gas atmosphere using a hot plate, melted, and held for 1 hour, then allowed to cool to room temperature. After cooling, the heated product was observed from the bottom side of the flat glass plate (the side opposite the top side) using a polarizing microscope using crossed Nicols polarization. The image data obtained at this time are shown in Figure 3. As shown in Figure 3, clear optical anisotropy was observed in the heated mesophase pitch.

[0131] <Thermogravimetric analysis> The mesophase pitch obtained above was subjected to thermogravimetric analysis by heating from room temperature to 900°C at a temperature increase rate of 10°C / min in a nitrogen gas atmosphere. The results are shown in Figure 16. As shown in Figure 16, a gradual and continuous weight loss was observed during heating, and then almost no weight change was observed, and finally a carbonized product was obtained.

[0132] Example 2 Step 1 was carried out in the same manner as in Example 1, except that gum rosin (manufactured by Harima Chemicals Co., Ltd.) (1 g) was used instead of abietic acid (1 g) and the amount of palladium-activated carbon used was changed from 0.025 g to 0.026 g, to obtain a solid (dehydrogenated product) (0.77 g).

[0133] The resulting solid (dehydrogenated product) and gum rosin (raw material) were respectively １ H-NMR (500MHz, CDCl ３ The obtained spectral data of the dehydrogenated product is shown in Figure 4. As shown in Figure 4, a peak of aromatic hydrogen was observed in the spectral data of the dehydrogenated product, which was not observed in the spectral data of the raw material, confirming that a dehydrogenated product of the terpenes in the gum rosin was indeed obtained by the first step.

[0134] The second step was carried out in the same manner as in Example 1, except that the amount of the solid obtained in the first step (i.e., the dehydrogenated product) used was changed from 0.211 g to 0.202 g, the amount of DDQ used was changed from 0.097 g to 0.201 g, the amount of dichloromethane used was changed from 25 mL to 50 mL, and the amount of trifluoromethanesulfonic acid used was changed from 0.025 mL to 0.075 mL, to obtain a polymer (mesophase pitch) (0.037 g).

[0135] The obtained mesophase pitch and the solid (dehydrogenated product) were each analyzed by MALDI-TOFMS in the same manner as in Example 1. The spectral data of the dehydrogenated product obtained at this time is shown in Figure 5A, and the spectral data of the mesophase pitch is shown in Figure 5B. As shown in Figure 5B, in this example as well, the spectral data of the mesophase pitch showed an increase in molecular weight compared to the dehydrogenated product, indicating that the desired mesophase pitch, which was a polymer of the dehydrogenated product, was indeed obtained by the second step.

[0136] Furthermore, the obtained mesophase pitch was subjected to CHNS elemental analysis in the same manner as in Example 1. The results are shown in Table 1.

[0137] The heated mesophase pitch obtained above was observed under polarized light using a polarizing microscope in the same manner as in Example 1, except that the heating temperature of the mesophase pitch was changed from 380°C to 330°C. The image data obtained at this time is shown in Figure 6. As shown in Figure 6, a clear optical anisotropy was observed in the heated mesophase pitch. Furthermore, as in Example 1, thermogravimetric analysis of the obtained mesophase pitch was performed. The results are shown in Figure 16. As shown in Figure 16, thermogravimetric changes similar to those in Example 1 were observed in this example.

[0138] Example 3 Step 1 was carried out in the same manner as in Example 1, except that tall rosin (manufactured by Harima Chemicals Co., Ltd.) (1 g) was used instead of abietic acid (1 g) and that the amount of palladium-activated carbon used was changed from 0.025 g to 0.028 g, thereby obtaining a solid (dehydrogenated product) (0.781 g).

[0139] The obtained solid (dehydrogenated product) and tall rosin (raw material) were respectively １ H-NMR (500MHz, CDCl ３ The obtained spectral data of the dehydrogenated product is shown in FIG. 7. As shown in FIG. 7, a peak of aromatic hydrogen was observed in the spectral data of the dehydrogenated product, which was not observed in the spectral data of the raw material, and it was confirmed that a dehydrogenated product of the terpenes in tall rosin was indeed obtained by the first step.

[0140] The second step was carried out in the same manner as in Example 1, except that the amount of the solid obtained in the first step (i.e., the dehydrogenated product) used was changed from 0.211 g to 0.207 g, the amount of DDQ used was changed from 0.097 g to 0.201 g, the amount of dichloromethane used was changed from 25 mL to 50 mL, and the amount of trifluoromethanesulfonic acid used was changed from 0.025 mL to 0.075 mL, to obtain a polymer (mesophase pitch) (0.022 g).

[0141] The obtained mesophase pitch and the solid (dehydrogenated product) were each analyzed by MALDI-TOFMS in the same manner as in Example 1. The spectral data of the dehydrogenated product obtained at this time is shown in FIG. 8A, and the spectral data of the mesophase pitch is shown in FIG. 8B. As shown in FIG. 8B, in this example as well, the spectral data of the mesophase pitch showed an increase in molecular weight compared to the dehydrogenated product, indicating that the desired mesophase pitch, which is a polymer of the dehydrogenated product, was indeed obtained by the second step.

[0142] Furthermore, the obtained mesophase pitch was subjected to CHNS elemental analysis in the same manner as in Example 1. The results are shown in Table 1.

[0143] As in Example 1, the heated mesophase pitch obtained above was observed under polarized light using a polarizing microscope. The image data obtained at this time is shown in FIG. 9. As shown in FIG. 9, clear optical anisotropy was observed in the heated mesophase pitch. Furthermore, as in Example 1, thermogravimetric analysis of the obtained mesophase pitch was performed. The results are shown in FIG. 16. As shown in FIG. 16, thermogravimetric changes similar to those in Example 1 were observed in this example.

[0144] Example 4 Step 1 was carried out in the same manner as in Example 1, except that tall oil pitch (manufactured by Harima Chemicals Co., Ltd.) (2.1 g) was used instead of abietic acid (1 g) and the amount of palladium-activated carbon used was changed from 0.025 g to 0.055 g, to obtain a solid (dehydrogenated product) (1.57 g).

[0145] The resulting solid (dehydrogenated product) and tall oil pitch (raw material) were respectively １ H-NMR (500MHz, CDCl ３ The obtained spectral data of the dehydrogenated product is shown in FIG. 10. As shown in FIG. 10, a peak of aromatic hydrogen was observed in the spectral data of the dehydrogenated product, which was not observed in the spectral data of the raw material. This confirmed that a dehydrogenated product of terpenes in tall oil pitch was indeed obtained by the first step.

[0146] The second step was carried out in the same manner as in Example 1, except that the amount of the solid obtained in the first step (i.e., the dehydrogenated product) used was changed from 0.211 g to 0.202 g, the amount of DDQ used was changed from 0.097 g to 0.099 g, the amount of dichloromethane used was changed from 25 mL to 50 mL, and the amount of trifluoromethanesulfonic acid used was changed from 0.025 mL to 0.038 mL, to obtain a polymer (mesophase pitch) (0.049 g).

[0147] The obtained mesophase pitch and the solid (dehydrogenated product) were each analyzed by MALDI-TOFMS in the same manner as in Example 1. The spectral data of the dehydrogenated product obtained at this time is shown in FIG. 11A, and the spectral data of the mesophase pitch is shown in FIG. 11B. As shown in FIG. 11B, in this example as well, the spectral data of the mesophase pitch showed an increase in molecular weight compared to the dehydrogenated product, indicating that the desired mesophase pitch, which is a polymer of the dehydrogenated product, was indeed obtained by the second step.

[0148] Furthermore, the obtained mesophase pitch was subjected to CHNS elemental analysis in the same manner as in Example 1. The results are shown in Table 1.

[0149] As in Example 1, the heated mesophase pitch obtained above was observed under polarized light using a polarizing microscope. The image data obtained at this time is shown in FIG. 12. As shown in FIG. 12, clear optical anisotropy was observed in the heated mesophase pitch. Furthermore, as in Example 1, thermogravimetric analysis of the obtained mesophase pitch was performed. The results are shown in FIG. 16. As shown in FIG. 16, thermogravimetric changes similar to those in Example 1 were observed in this example.

[0150] <<Production of Mesophase Pitch (Second Production Method) and Evaluation (Example 5)>> [Example 5] A polymerized rosin (manufactured by Harima Chemicals Co., Ltd.) corresponding to a polymer of gum rosin (manufactured by Harima Chemicals Co., Ltd.) was prepared (Step 3). This polymerized rosin contained a polymer of terpenes contained in gum rosin. A step (dehydrogenation) similar to Step 1 in Example 1 was carried out, except that the polymerized rosin (1 g) was used instead of abietic acid (1 g), to obtain a solid (dehydrogenated product) (0.88 g) (Step 4).

[0151] The solid obtained in the fourth step (i.e., the dehydrogenated product) was analyzed by MALDI-TOFMS in the same manner as in Example 1. The spectrum data of the dehydrogenated product obtained at this time is shown in Figure 13. As is clear from Figure 13, the molecular weight of the dehydrogenated product was 600 or less, which was smaller than that of the other Examples, and further, the carbonization yield when the dehydrogenated product was heated to 900°C was low.

[0152] Therefore, the same step (polymerization) as in the second step in Example 1 was carried out using the dehydrogenated product, except that the amount used was changed from 0.211 g to 0.207 g, the amount of DDQ used was changed from 0.097 g to 0.098 g, the amount of dichloromethane used was changed from 25 mL to 50 mL, and the amount of trifluoromethanesulfonic acid used was changed from 0.025 mL to 0.036 mL, to obtain a polymer (mesophase pitch) (0.014 g).

[0153] The obtained mesophase pitch was analyzed by MALDI-TOFMS in the same manner as in Example 1. The spectrum data of the mesophase pitch obtained at this time is shown in Figure 14. As shown in Figure 14, the spectrum data of the mesophase pitch confirmed an increase in molecular weight compared to the dehydrogenated product, indicating that the desired mesophase pitch had indeed been obtained.

[0154] Furthermore, the obtained mesophase pitch was subjected to CHNS elemental analysis in the same manner as in Example 1. The results are shown in Table 1.

[0155] As in Example 1, the heated mesophase pitch obtained above was observed under polarized light using a polarizing microscope. The image data obtained at this time is shown in FIG. 15. As shown in FIG. 15, clear optical anisotropy was observed in the heated mesophase pitch. Furthermore, as in Example 1, thermogravimetric analysis of the obtained mesophase pitch was performed. The results are shown in FIG. 16. As shown in FIG. 16, thermogravimetric changes similar to those in Example 1 were observed in this example.

[0156] Furthermore, FIG. 16 shows that the weight loss rate of the mesophase pitch upon heating decreased in the order of Examples 1, 2, 3, 5, and 4, suggesting that the conversion rate of mesophase pitch to a carbon material increased in this order.

[0157]

[0158] <<Discussion of the Results of Elemental Analysis of Mesophase Pitch>> As shown in Table 1, the sulfur contents of the mesophase pitches of Examples 1 to 5 were clearly lower than those of mesophase pitch derived from fossil resources. In the case of Example 1, this was because the abietic acid used as the main raw material did not contain sulfur atoms. In the cases of Examples 2 to 5, it was presumed that the gum rosin, tall rosin, tall oil pitch, and polymerized rosin used as the main raw materials were all derived from biomass and contained no sulfur or only a small amount of sulfur. However, the detection of sulfur in Example 1 was presumed to be due to trace amounts of impurities contained in the DDQ used in the second step. The trifluoromethanesulfonic acid (CF ３ SO ３ Although the mesophase pitch (H) contains sulfur atoms, it was presumed that these are removed by washing and are unrelated to the sulfur content. That is, in the production method of this embodiment, it was confirmed that by avoiding the use of raw materials containing sulfur atoms or reducing the amount used, the sulfur content can be reduced compared to mesophase pitch derived from fossil resources. The mesophase pitches of Examples 1, 3, and 5 were superior in that they had low sulfur contents or no detected sulfur, and the mesophase pitches of Examples 3 and 5 were particularly superior.

[0159] On the other hand, the mesophase pitches of Examples 1 to 5 had a higher nitrogen content than the petroleum-based mesophase pitches. This is because the nitrogen atoms in the DDQ (C ６ O ２ Cl ２ (CN) ２ In other words, it was confirmed that in the production method of this embodiment, similar to the case of sulfur atoms, by avoiding the use of raw materials containing nitrogen atoms or reducing the amount of such raw materials used, it is highly likely that the nitrogen content can be reduced compared to mesophase pitch derived from fossil resources. The mesophase pitch of Example 1 was superior in terms of its low nitrogen content.

[0160] In terms of both low sulfur and nitrogen contents, the mesophase pitch of Example 1 was the most excellent. This was due to the effect of selecting and using a raw material that clearly contained neither sulfur atoms nor nitrogen atoms.

[0161] The present disclosure is applicable to the production of mesophase pitch, and further applicable to the production of carbon materials from mesophase pitch.

Claims

1. A method for producing mesophase pitch, comprising: a first production method having a first step of preparing a dehydrogenated product of terpenes, and a second step of polymerizing the dehydrogenated product to obtain mesophase pitch; or a second production method having a third step of preparing a polymer of terpenes, and a fourth step of dehydrogenating the polymer to obtain mesophase pitch.

2. The method for producing mesophase pitch according to claim 1, wherein the terpenes are one or more terpenes selected from a first group consisting of abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid, levopimaric acid, dihydroabietic acid, and tetrahydroabietic acid, and one or more terpenes contained in one or more terpenes selected from a second group consisting of raw pine resin, tall rosin, gum rosin, wood rosin, and tall oil pitch.

3. A method for producing carbon fibers, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to claim 1 or 2, and then spinning the mesophase pitch, infusibilizing it, and carbonizing it to obtain carbon fibers.

4. A method for producing needle coke, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to claim 1 or 2, and then pyrolyzing and carbonizing the mesophase pitch to obtain needle coke.

5. A method for producing a binder, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to claim 1 or 2, and then mixing the mesophase pitch with a component other than the mesophase pitch or heat treating the mesophase pitch to obtain a binder having a different softening point or carbonization yield.

6. A method for producing mesocarbon microbeads, comprising obtaining mesophase pitch by the method for producing mesophase pitch according to claim 1 or 2, and then heat-treating the mesophase pitch to obtain mesocarbon microbeads.

7. A method for producing a carbon electrode material, comprising obtaining needle coke by the method for producing needle coke as set forth in claim 4, and then using the needle coke to produce a carbon electrode material.

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