KR102236622B1 - A method for isotropic pitch for manufacturing carbon fiber - Google Patents

Abstract

The present invention relates to a method for producing an isotropic pitch through a manufacturing method suitable for a raw material having a content of a specific compound, a ratio and physical properties thereof, and a raw material produced in an intermediate step, and the isotropic pitch produced according to the present invention is excellent. It has spinnability and physical properties, so it is possible to manufacture high-strength, highly elastic carbon fibers.

Description

Method for manufacturing isotropic pitch for manufacturing carbon fiber {A method for isotropic pitch for manufacturing carbon fiber}

The present invention is a method for producing an isotropic pitch, in which the content and ratio of specific compounds contained in the raw material and the raw material produced in the manufacturing step including one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar fraction are very The isotropic pitch that satisfies the limiting conditions and is manufactured by a manufacturing method suitable for this is excellent in physical properties and spinning It can be used to manufacture high elasticity, high strength carbon fiber.

Carbon fiber is light in weight compared to its relatively strong strength, so it can be used in various fields such as sports goods, aviation industry, and automobiles, so many studies are being conducted to obtain high strength and high elasticity carbon fiber. Mainly, high-strength, high-elasticity carbon fibers are mainly produced by oxidation-stabilizing and carbonizing PAN-based copolymerized polymer fibers. In addition, carbon fibers having high strength and high elasticity can be manufactured using anisotropic pitch, but there is a problem in that the manufacturing process is cumbersome and cost increases for the production of carbon fibers reaching the desired strength and elasticity level. For this reason, in recent years, studies on the production of high-strength, high-elasticity carbon fibers using isotropic pitch have been actively conducted.

Naphtha cracker bottom oil (NCB oil) is attracting attention for the production of pitch-based carbon fiber, and naphtha cracker bottom oil (NCB oil) is a by-product generated in the naphtha cracking process. It is known to be suitable for manufacturing carbon materials due to its low insoluble content. The naphtha decomposition residue may be prepared as an isotropic pitch or anisotropic pitch for producing a pitch-based carbon fiber depending on conditions during heat treatment. Among them, the isotropic pitch is amorphous, and since the carbon fiber produced therefrom has low strength, anisotropic pitch is mainly used for the production of high strength and high elasticity carbon fiber. In addition to the naphtha cracking residue, petroleum heavy oil, oil, and coal tar are also used in the manufacture of carbon materials.

In order to manufacture high-strength and high-elasticity carbon fibers, the physical properties and composition of the isotropic pitch are important. In particular, it is possible to manufacture high-strength carbon fibers only when an isotropic pitch for producing carbon fibers having a certain range and level of molecular weight, softening point, and viscosity is used. In the case of Japanese Patent Laid-Open No. 1996-144131, an isotropic pitch for producing carbon fibers having a certain range of molecular weight was invented, but the carbon fibers produced therefrom had low tensile strength and could be used only as general-purpose materials like conventional isotropic pitch-based carbon fibers. In addition, in recent years, a method for producing an isotropic pitch using a catalyst has been proposed, but it does not seem to be known about the specific physical properties of the carbon fiber produced therefrom.

Most of the conventional inventions mainly paid attention to a manufacturing method such as using a catalyst to prepare an isotropic pitch for carbon fiber, and it was difficult to find a study on a manufacturing method suitable for it from the analysis of raw materials.

Recognizing this problem, the present inventors conducted research on a manufacturing method suitable for the analysis of raw materials for isotropic pitch for manufacturing carbon fiber, and as a result, inventing an isotropic pitch capable of manufacturing high strength and high elastic carbon fiber and a manufacturing method thereof. Arrived.

Japanese registered patent 3695077

The present invention provides a method for producing an isotropic pitch that can be used for the production of high strength, high elastic carbon fibers with excellent physical properties and spinnability, and a raw material comprising at least one of naphtha decomposition residue oil, petroleum heavy oil, or coal tar oil And it can be achieved by the analysis of the raw material produced in the intermediate step and a manufacturing method suitable thereto.

The present invention relates to a method for producing an isotropic pitch, in a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar fraction satisfying a specific range of physical properties, compound content, and ratios thereof, and in an intermediate step Provides the raw materials to be produced and a manufacturing method suitable therefor.

In the present invention, the raw material may be obtained by pretreating a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar oil.

In the present invention, the pretreatment may include heating and fractionation.

The present invention provides a manufacturing method in which the raw material produced in the intermediate step of the isotropic pitch manufacturing method satisfies a specific range in terms of atomic ratio, degree of aromatization, average molecular weight, content of compounds contained, and ratios thereof.

In the present invention, there is provided a method for producing an isotropic pitch in which the raw material undergoes thermal polymerization and heating steps.

It provides an isotropic pitch produced according to the present invention.

The manufacturing method according to the present invention can produce isotropic pitch having characteristic physical properties and excellent spinnability in high yield, and using the prepared isotropic pitch to produce carbon fibers of high strength and high elasticity that can be used in carbon composites. I can.

Fig. 1 shows a process of manufacturing a raw material of isotropic pitch and an isotropic pitch from NCB oil, which is a raw material.
2 shows representative compositions of raw materials and raw materials produced in an intermediate step.

Terms that are not separately defined in the description of the present invention may be understood to be suitable for those of ordinary skill in the field to which the present invention belongs to understand the contents of the present invention, and will obscure the subject matter of the present invention in the description and the accompanying drawings. The contents of the possible notice may not be separately described.

The present invention is a method for thermally polymerizing and heating raw materials obtained by pretreating raw materials containing at least one of naphta cracking botto oil (NCBO), petroleum heavys, or coal tar fraction.

The present invention is a method for producing an isotropic pitch in which a raw material obtained by pretreating a raw material containing at least one or more of naphta cracking botto oil petroleum-based heavy oil or coal tar oil is thermally polymerized and heated.

The naphtha cracking residual oil may include pyrolysis fuel oil (PFO), which is a kind of naphtha cracking process residual oil. PFO is produced at the bottom of the naphtha cracking center (NCC) and has a high degree of aroma and rich in resin content. In addition, PFO contains not only saturated compounds, but also various aromatic hydrocarbons such as benzene, naphthalene, indenene, and biphenyl.

Not only the naphtha cracking residue, but also petroleum heavy or coal tar oil contains saturated compounds and various aromatic hydrocarbons, so that it can be used for the production of pitch and carbon fibers.

The physical properties and composition of the raw material for isotropic pitch production can be adjusted according to the pretreatment conditions of the raw material containing at least one of naphtha decomposition residue oil, petroleum heavy oil, or coal tar oil, and the physical properties and composition of the raw material are high strength and high elasticity. It has an important influence on the production of isotropic pitch for the production of carbon fiber.

In the present invention, the method for producing an isotropic pitch,

(a) producing a raw material by pretreating a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar oil; And

(b) thermally polymerizing and heating the raw material prepared in (a);

It is a method for producing an isotropic pitch comprising a.

In the manufacturing method, the pretreatment may include heating and fractionation, and low molecular weight substances that are unlikely to generate oligomers can be removed by thermal polymerization, and at the same time, the reactivity contained in the raw material is strong and unstable due to various reactions. The compound can be removed. For example, one of the main objectives is to convert a compound containing a single benzene ring such as alkenyl benzenes or indenes, which may cause negative side reactions in the isotropic pitch synthesis step, to a more stable and effective compound for the production of isotropic pitch. can see. The pretreatment may be performed by heating and fractionating the raw material at normal pressure at a temperature of 150 to 260°C, preferably 160 to 240°C, more preferably 175 to 235°C until no more volatiles are generated.

The pretreatment may be performed under pressure or reduced pressure. The process can be carried out at a lower temperature under reduced pressure, and when pressurized, a higher temperature is required, but there is an advantage of being able to fractionate more precisely by supplementing the design of the device. The pretreatment process can freely control the pressure and temperature within a range that can obtain the same effect as normal pressure. In addition, after distillation, the filtration process may be performed under normal pressure, pressurization, or reduced pressure as needed.

The filtration step removes the solid material, and the solid material is a solid residue containing impurities such as metal, sulfur, nitrogen, etc., and acts as a cracker in the structure of the carbon fiber produced from isotropic pitch, causing a decrease in strength. I can.

The filtration step may be performed in a manner commonly performed in the art, for example, filtration, centrifugation, sedimentation, adsorption, extraction, and the like.

The main physical properties of the raw material produced in the intermediate step of the manufacturing method of the present invention are important. Among the main physical properties, there are atomic ratio of carbon and hydrogen, degree of aromatization, average molecular weight, etc., and having a specific range of physical properties has a great influence on the method of manufacturing an isotropic pitch and further, manufacturing of high-strength high elastic carbon fibers.

The degree of aromatization (fa) of the raw material may be 0.70 to 0.95, preferably 0.75 to 0.90. When the degree of aromatization is low, the carbonization yield may decrease. There is no particular limitation on the case where the degree of aromatization is high, but it may not be easy to manufacture the isotropic pitch disclosed in the present invention if it is more than the above-described preferred range.

The average molecular weight (Mw) of the raw material may have a distribution of 150 to 300, preferably 185 to 290, more preferably 190 to 245. The range of the appropriate molecular weight of the raw material affects the molecular weight of the isotropic pitch to be produced, and the range of the specific molecular weight of the isotropic pitch has an important influence on the production of high strength and high elasticity carbon fibers. If the molecular weight is low, the molecular weight of the produced isotropic pitch is also low, so it may be difficult to manufacture carbon fibers of the desired strength.If the molecular weight is high, the effect of precisely controlled thermal polymerization and heating for the production of high strength carbon fibers may be low. have.

The raw material containing at least one or more of naphtha decomposition residue, petroleum heavy or coal tar fraction of the present invention, and the compound contained in the raw material produced in the intermediate step, depending on the number of aromatic rings, are saturated compounds, one aromatic It may be composed of a compound containing a ring, a compound containing two aromatic rings, a compound containing three aromatic rings, and a compound containing more than four aromatic rings. The compounds may include a condensed polycyclic compound structure or a polycyclic compound structure in which an aromatic ring is connected by single or multiple bonds, such as biphenyl. For example, these compounds include, but are not limited to, benzene, indenes, naphthalenes, biphenyls, and anthracenes, and a wide variety of compounds and derivatives including an aromatic ring may exist.

The types of compounds containing aromatic rings in raw materials containing at least one or more of naphtha decomposition residues, petroleum heavys, or coal tar fractions and raw materials produced in the intermediate stage are very diverse, but among them, the object of the present invention is For the production of isotropic pitch, there are main compounds whose content needs to be adjusted among the raw materials and the compounds contained in the raw materials.

Among compounds containing one aromatic ring, the content of alkenyl benzene and indenes is particularly important, and among compounds containing two aromatic rings, it is particularly important to control the content of biphenyls and naphthalenes. The content of the compound containing more than two aromatic rings must be adjusted as a whole to produce an isotropic pitch excellent in physical properties and spinnability, and finally, a carbon fiber having high elasticity and high strength properties can be produced. The reason is that in the pitch synthesis step, a mesophase is partially generated in an insoluble solid or synthesized pitch by compounds that do not participate in the reaction or are too reactive. These insoluble solids and mesophase portions become a major factor deteriorating the physical properties and spinnability of the pitch and the mechanical properties of the carbon fiber, so that the isotropic pitch for producing high-strength carbon fibers that is desired in the present invention cannot be obtained.

That is, the isotropic pitch for producing high-strength, high-elastic carbon fiber can be manufactured only when very limited conditions are satisfied.

In the present invention, when the content of the compound contained in the raw material containing at least one or more of naphtha decomposition residue, petroleum heavy, or coal tar fraction and the raw material produced in the intermediate step and the content ratio thereof are included in a specific range, the above It satisfies very limited conditions, and through this, it is possible to manufacture an isotropic pitch for producing high strength and high elastic carbon fibers.

First, the content of the raw material produced in the intermediate step for producing the isotropic pitch desired in the present invention will be described in detail.

The compound containing one aromatic ring is 20.0 to 45.0% by weight, preferably 30.0 to 40.0% by weight, and more preferably 35.0 to 40.0% by weight, based on the total amount of the raw material. Among them, indenes are materials with very strong reactivity, which accompany various side reactions during the process of synthesizing pitches that are stored for a long time or at high temperatures, and can produce insoluble solids or partially fished mesophases in the polymerization stage of pitches. It is necessary to limit the content. The content of indenes is 75.0% by weight or less, preferably 35.0 to 75.0% by weight, based on the total amount of the compound containing one aromatic ring, and 5.0 to 30.0% by weight, preferably 15.0 to 25.0% by weight, based on the total amount of raw materials. , It can be adjusted to satisfy the ratio of the naphthalene content and a specific range. In addition, alkenyl benzenes, which are olefins, have very strong reactivity similar to indenes, and it is difficult to produce an isotropic pitch of desired physical properties by providing protons and electrons to the surrounding compounds in the polymerization step of the pitch to induce a wide variety of side reactions. In the case of alkenyl benzenes, most can be removed by volatilization during the pretreatment process.

The compound containing two aromatic rings is 50.0 to 70.0% by weight, preferably 55.0 to 65.0% by weight, more preferably 55.0 to 60.0% by weight, based on the total amount of the raw material. Among them, the content of naphthalenes is 30.0% by weight or more, preferably 35.0% by weight or more, and 15.0 to 75.0% by weight, preferably 20.0 to 60.0% by weight, based on the total amount of the compound containing two aromatic rings. , More preferably 30.0 to 50.0% by weight. Since biphenyls do not contribute significantly to the polymerization reaction, the lower the content is, the better.It is 15.0% by weight or less, preferably 10.0% by weight or less, and more preferably, it is measurable with respect to the total amount of the compound containing two aromatic rings. It is preferable that a very small amount is included or not so as to be absent, 10.0% by weight or less, preferably 5.0% by weight or less, and more preferably a very small amount so as not to be measurable, relative to the total amount of the raw material.

Compounds containing three aromatic rings and compounds containing four or more aromatic rings do not participate in the polymerization reaction or condensed aromatics having an excessively large number of rings under the influence of olefins such as alkenyl benzene and leadene compounds such as indene. Cyclic compounds can be formed. Such condensed aromatic ring compounds easily form a layered structure and form a mesophase partially in an insoluble solid or synthesized pitch, so it is necessary to control the content of a compound containing three and four or more aromatic rings. The compound containing three aromatic rings is preferably 10.0% by weight or less, preferably 5.0% by weight or less, and more preferably in a very small amount so as not to be measurable, based on the total amount of the raw material. The compound containing four or more aromatic rings is preferably 5.0% by weight or less, preferably 3.0% by weight or less, and more preferably in a very small amount so as not to be measurable, based on the total amount of the raw material.

In order to prepare the isotropic pitch for the purpose of the present invention, the compounds contained in the raw materials as described above must satisfy their respective contents, and together with them, they must satisfy a specific content ratio, which will be described in detail.

The content ratio of the compound contained in the raw material produced in the intermediate step of the present invention should satisfy the following.

Each of the content ratio of the compound containing an aromatic ring in _{Ar 1 / Ar 2 0.30 <Ar} 1 / Ar 2 <0.75, preferably _{0.40 <Ar 1 / Ar 2 <} 0.70, more preferably 0.65 <Ar ₁ / Ar ₂ <0.70. Next, in Ar ₁ /Ar ₃ , 2.00 <Ar ₁ /Ar ₃ <12.00, preferably 4.00 <Ar ₁ /Ar ₃ <10.00, more preferably 8.00 <Ar ₁ /Ar ₃ <9.00. And Ar ₃ /Ar ₂ in Ar ₃ /Ar ₂ <0.20, preferably Ar ₃ /Ar ₂ <0.15, more preferably Ar ₃ /Ar ₂ <0.10 to be. In the above content ratio, Ar ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, Ar ₂ is the content of the compound containing two aromatic rings relative to _{the total amount of the raw material, and Ar 3} is the content of the compound containing two aromatic rings relative to the total amount of the raw material. It indicates the content of the compound containing two aromatic rings. In addition, a compound containing four or more aromatic rings relative to the total amount of raw materials can be represented _{by Ar 4.}

The content ratio of indenes and naphthalenes relative to the total amount of raw materials is 0.10 <weight of indenes / weight of naphthalenes <2.00, preferably 0.15 <weight of indens / weight of naphthalenes <1.50, more preferably 0.50 <weight of indens / The weight of naphthalenes is <0.80.

The lower the content ratio of biphenyls and naphthalenes to the total amount of raw materials is, the better, but it is particularly important that the weight of biphenyls/naphthalenes is <0.20, preferably the weight of biphenyls/naphthalenes is <0.15. . When the content ratio (weight ratio) of biphenyls and naphthalenes of the raw material produced in the intermediate step is 0.20 or more, the reason is not clear, but the spinning property and physical properties of the produced isotropic pitch are not good, and the tensile strength when manufacturing carbon fiber is not Significantly decreases.

In order to produce the desired isotropic pitch in the present invention, a raw material that satisfies the content of the compounds described above and their ratio must be produced in an intermediate step. For example Ar ₁ , An isotropic pitch can be prepared through the control of the contents of _{Ar 2} and Ar _{3 and Ar 1} /Ar ₂ , and more specifically, the content of indenes, naphthalenes, and biphenyls, and their ratios are further adjusted. In the present invention, the desired isotropic pitch can be produced.

If a raw material that partially satisfies the content of the compounds and their ratios described above is produced in an intermediate step, the spinnability of the isotropic pitch is not good, and the strength of the finally produced carbon fiber may decrease rapidly, and the elongation rate may also decrease. . For example, in the content ratio, the weight of biphenyls / weight of naphthalenes is important, but if it is out of the above preferred range, the physical properties and spinnability of the isotropic pitch are not good even if other conditions are satisfied, and the strength of the carbon fiber produced therefrom is rapidly reduced. can do.

According to an embodiment of the present invention, when a raw material partially satisfying the content and the ratio thereof is produced in an intermediate step, the produced isotropic pitch can be melt-spinned, but the spinning is not good due to the high frequency of single yarns. According to another embodiment of the present invention, even if the single yarn frequency is not high, the carbon fiber produced from the isotropic pitch has poor strength and elongation. On the other hand, according to an embodiment of the present invention, when the content and raw materials satisfying them are produced in an intermediate step, melt spinning is possible to produce carbon fibers having a strength of at least 1.5 GPa or more and an elongation of 2% or more. Isotropic pitch without single yarn frequency can be produced.

When a raw material that satisfies the compound content and ratio of the raw materials described above is produced in an intermediate step, an isotropic pitch having very excellent spinning properties can be prepared, and the carbon fiber produced therefrom can have high strength and high elastic properties. Satisfies.

The isotropic pitch prepared in the present invention has a softening point (°C) of 250 to 280, preferably 260 to 270, and an average molecular weight (Mw) of 1450 to 2850, preferably 1600 to 2600, more preferably 1700 to 2500. . The physical properties of the isotropic pitch of the present invention affect the excellent spinnability and physical properties of the carbon fiber produced therefrom, and the specific properties of the isotropic pitch appearing while having the above properties are also spinnability and the physical properties of carbon fibers produced therefrom. Is an important factor.

The isotropic pitch produced in the present invention is capable of melt spinning, and has excellent spinning properties that do not occur or are extremely rare during fiber spinning. Melt spinning is a method of manufacturing continuous fibers by melting a polymer material or pitch, and it is a very economical method that can simplify the configuration of the spinning process and significantly reduce the cost because it does not require the use of expensive solvents required for fiber spinning. to be. In order to enable the melt spinning for the production of carbon fibers, the spinnability of the pitch must be excellent, but the isotropic pitch produced according to the present invention has excellent spinnability, enabling melt spinning for the production of carbon fibers, and single yarn is extremely rare or does not occur. . In addition, the melt-spinning isotropic pitch of the present invention has excellent spinnability compared to the conventional isotropic pitch, which was limited to producing short fibers through melt-blowing, and from this, it is possible to manufacture high-strength, high-elasticity carbon fibers. have.

According to an embodiment of the present invention, as a result of measuring the frequency of interruption during melt spinning at 700 rpm for 20 minutes in a row as a single yarn frequency, the single yarn frequency corresponds to 0, so that the spinning property is very excellent.

The isotropic pitch prepared in the present invention can produce high-strength, high-elasticity carbon fibers, and has very good strength and high elongation than conventional carbon fibers. Conventional isotropic pitch-based carbon fiber was used as a general-purpose carbon fiber due to its low strength, but the carbon fiber produced from the isotropic pitch of the present invention has very good strength and high elongation, so anisotropic pitch-based carbon fiber or PAN-based carbon fiber is used. It can also be used for conventional carbon reinforced composites.

According to an embodiment of the present invention, a carbon fiber having an isotropic pitch of 1.5 GPa or more and an elongation of 2% or more can be manufactured with an isotropic pitch manufactured by the manufacturing method of the present invention. Carbon fiber having such physical properties satisfies the strength that can be applied to carbon composites, materials, materials, etc. and has a wide range of applications.

That is, the isotropic pitch of the present invention, which can be melt-spun to produce very economical, high-strength, and highly elastic carbon fibers, has an effect that cannot be obtained from the existing isotropic pitch.

The raw material produced in the intermediate step described above is a method of pretreating a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar fraction, or a raw material containing a specific range of compound composition together with it. It can be created in an intermediate step.

The above raw materials It is preferable that the pretreatment method includes heating and fractionation at normal pressure. The heating may be performed by heating and fractionating at a temperature of 160 to 240°C, preferably 175 to 235°C until no more volatiles are generated. When heating at the above temperature, the raw material produced in the intermediate step of the production method of the present invention may satisfy the content of the compound for producing isotropic pitch and the ratio thereof. Specifically, when the temperature is exceeded, indenes are not sufficiently converted to naphthalenes, and the content of naphthalenes may be insufficient. In addition, the content of indenes, compounds containing three or more aromatic rings, or other compounds may be excessively decreased or increased. In addition, the content of biphenyls is excessively increased, so that raw materials not suitable for isotropic pitch having physical properties and spinnability to be produced may be produced in an intermediate step.

The method for producing an isotropic pitch that satisfies the conditions of the raw material produced in the intermediate step described above,

(a) preparing raw materials satisfying the following formulas (1) to (4) by pretreating a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar fraction at 160 to 240°C. ; And

20.0% by weight ≤ Ar ₁ ≤ 45.0% by weight --- (1)

50.0 wt% ≤ Ar ₂ ≤ 70.0 wt% --- (2)

0.0% by weight ≤ Ar ₃ ≤ 10.0% by weight --- (3)

0.30 <Ar ₁ /Ar ₂ <0.75 --- (4)

(b) It can be represented by a method of manufacturing an isotropic pitch comprising the steps of thermal polymerization and heating the raw material prepared in (a).

According to an embodiment of the present invention, when the pretreatment temperature is 150° C. or less, the above equations (1) and (4) are not satisfied, and the content of indenes is too high, while the content of naphthalenes is too small. According to another embodiment of the present invention, when the pretreatment temperature is 250° C. or higher, the above equation (4) is not satisfied, and the content of biphenyls is too high, while the content of naphthalenes is too small.

According to an embodiment of the present invention, even if the above (1), (2) and (3) are satisfied, if the content ratio (4) is not satisfied, the single yarn frequency is high during melt spinning of the isotropic pitch, The strength of carbon fiber is less than 1.0 GPa. According to another embodiment, even if the above (1) and (2) are satisfied and the content ratio (4) is satisfied, if the above (3) is not satisfied, the strength of the carbon fiber produced from the isotropic pitch is less than 1.0 GPa. It is not possible and the elongation rate drops to less than 2%. According to another embodiment, even if the above (2) and (4) are satisfied, if the above (1) or (3) is not satisfied, the single yarn frequency is high during melt spinning of the isotropic pitch, and the elongation rate of the produced carbon fiber is It falls below 2%.

While satisfying (1) to (4) of the above manufacturing method, the naphthalene content of the raw material produced in the intermediate step is 20.0 to 60.0% by weight, the biphenyl content is 5.0% by weight or less, and the ratio of the content It is preferable that the weight of phenyls/weight of naphthalenes is less than 0.20. According to an embodiment of the present invention, when the content of naphthalenes and biphenyls and the content ratio thereof do not satisfy (1) to (4) of the above production method, even if the content of naphthalenes and biphenyls are within the above preferred range, single yarn during melt spinning of the isotropic pitch The frequency may be high, and the strength of the produced carbon fiber is significantly lowered or the elongation rate is lowered. According to another embodiment, even if the content ratio of naphthalenes and biphenyls satisfies the above preferred range, even if the content of naphthalenes or biphenyls does not satisfy the above preferred range, the single yarn frequency during melt spinning of the isotropic pitch may be high. In addition, the strength of the carbon fiber to be produced is significantly lowered or the elongation rate is lowered.

to the next, In raw materials containing at least one or more of naphtha decomposition residue oil, petroleum heavy substances, or coal tar oil The raw material for isotropic pitch production in the production method of the present invention may be produced in an intermediate step according to the content of the included compound and the content ratio thereof.
The raw material including at least one or more of the naphtha decomposition residue oil, petroleum-based heavy oil, or coal tar oil may satisfy the following equations (1) to (5).
30.0% ≤ Ar' ₁ ≤ 60.0% --- (1)
55.0% ≤ Ar' ₂ ≤ 70.0% --- (2)
0.55 <Ar' ₁ /Ar' ₂ <1.75 --- (3)
0.0% ≤ Ar' ₃ ≤ 5.0% --- (4)
0.0% ≤ Ar' ₄ ≤ 3.0% --- (5)
(The Ar' ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, the Ar' ₂ is the content of the compound containing two aromatic rings relative to the total amount of the raw material, and Ar' ₃ Is the content of the compound containing three aromatic rings relative to the total amount of the raw material, and Ar' ₄ is the content of the compound containing four or more aromatic rings relative to the total amount of the raw material.)

Specifically, the compound containing one aromatic ring is preferably 30.0 to 60.0% by weight based on the total amount of the raw material. Among them, some of indenes may be converted to naphthalenes during the pretreatment process, but since it is a material having a strong reactivity, it may adversely affect the physical properties and radioactivity of the isotropic pitch to be produced, so it is necessary to limit the content. The content of indenes is 25.0 to 70.0% by weight, preferably 30.0 to 65.0% by weight, based on the total amount of the compound containing one aromatic ring, and 5.0 to 50.0% by weight, preferably 10.0 to 40.0, based on the total amount of the raw material. It is weight percent. In addition, alkenyl benzenes, which are olefins, also have very strong reactivity similar to indenes, and may adversely affect the physical properties and radioactivity of the isotropic pitch to be produced later, but most of them are volatilized during the pretreatment process, and the content is not greatly limited. It is not more than 3.0% by weight.

The compound containing two aromatic rings is 30.0% by weight or more, preferably 35.0 to 80.0% by weight, more preferably 55.0 to 70.0% by weight, based on the total amount of the raw material. Among them, the content of naphthalenes is 30.0% by weight or more, preferably 35.0% by weight or more, based on the total amount of the compound containing two aromatic rings, and 5.0 to 60.0% by weight, preferably 10.0 to 45.0% by weight, based on the total amount of the raw material. It should be% so that raw materials containing sufficient naphthalenes can be produced in the intermediate stage. Since biphenyls do not contribute significantly to the polymerization reaction, the lower the content is, the better, but 15.0% by weight or less, preferably 10.0% by weight or less, and 10.0% by weight relative to the total amount of the raw material. % Or less, preferably 5.0% by weight or less, more preferably in a very small amount or not so that it cannot be measured.

Compounds containing three aromatic rings and compounds containing four or more aromatic rings do not participate in the polymerization reaction or condensed aromatics having an excessively large number of rings under the influence of olefins such as alkenyl benzene and leadene compounds such as indene. Cyclic compounds can be formed. That is, in the isotropic pitch manufacturing method, a desired raw material may not be produced in an intermediate step of the isotropic pitch. The compound containing three aromatic rings is 8.0% by weight or less, preferably 5.0% by weight or less, more preferably in a very small amount or not so that it cannot be measured, based on the total amount of the raw material, and contains four or more aromatic rings. It is preferable that the compound is 3.0% by weight or less, and preferably contains or does not contain a very small amount so as not to be able to measure it.

Each of the content ratio (by weight) of a compound containing an aromatic ring is in _{0.50 <Ar '1 / Ar'} 2 <2.00, preferably _{0.55 <Ar '1 / Ar'} 2 <1.75 in Ar _'1 / Ar' _2. Next, in Ar' ₁ /Ar' ₃ , 5.00<Ar' ₁ /Ar' ₃ <30.00, preferably 8.00<Ar' ₁ /Ar' ₃ <25.00. And in Ar' ₃ /Ar' ₂ , 5.00<Ar' ₃ /Ar' ₂ <20.00, preferably 10.00<Ar' ₃ /Ar' ₂ <15.00 to be. In the content ratio, Ar' ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, Ar' ₂ is the content of the compound containing two aromatic rings relative to the total amount of the raw material, Ar' ₃ represents the content of the compound containing three aromatic rings relative to the total amount of the raw material. In addition, compounds containing more than three aromatic rings than the total amount of the raw material may be represented by Ar ₄ '.

Of raw materials containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar oil The content ratio (weight ratio) of indenes and naphthalenes to the total amount is 0.20<indenes weight/naphthalenes weight <4.00, preferably 0.25<indenes weight/naphthalenes weight<3.50.

The content ratio (weight ratio) of biphenyls and naphthalenes to the total amount of compounds containing two aromatic rings in the raw material is biphenyls weight/naphthalenes weight <0.15, preferably biphenyls weight/naphthalenes weight< Is 0.10.

It is preferable to use a raw material that satisfies the content of the compound contained in the raw material and the ratio thereof. For example Ar' ₁ , Through the control of the content of Ar' _{2 and Ar' 1} /Ar' ₂ , the raw material produced in the intermediate step of the present invention can be satisfied. And more specifically, the content and ratio of specific compounds such as indenes, naphthalenes, and biphenyls may be further controlled.

According to an embodiment of the present invention, when a naphtha decomposition residue partially satisfying the content and ratio of the compound contained in the raw material is used, the content and ratio of the raw material generated in the intermediate step may not be appropriate. For example, indenes/naphthalenes are important in the content ratio of the raw material, but if it is out of the above-described preferred range, the content and ratio of the raw material produced in the intermediate step may not be appropriate even if other conditions are satisfied.

In the present invention, the thermal polymerization performed after the raw material is generated may be performed at 350 to 380°C for 0.1 to 2 hours, but is not limited thereto. The thermal polymerization method can be carried out in an inert gas atmosphere during the process, and can be carried out by separating nitrogen and gaseous by-products generated during the poly-condensation process. It is recommended that the reaction temperature does not exceed 380°C. When the reaction temperature exceeds 380°C, insoluble solids are generated, excessive mesophases exceeding the range of uniform isotropic pitch are generated, or coking proceeds to carbon fiber. During manufacture, non-uniform carbon fibers may be produced.

Next, heating may be a process of promoting evaporation to suppress generation of mesophase, and producing an isotropic pitch capable of spinning. The heating can be performed by a conventional thin film distillation method, and there is an advantage of not requiring an additional process of removing insoluble solids as well as suppressing the formation of mesophase through this.

The isotropic pitch prepared according to the production method of the present invention is excellent in molecular weight, high softening point, and spinnability in a specific range, from which it is possible to manufacture carbon oil having high strength and high elasticity.

The carbon fiber may be manufactured through a stabilization step and a carbonization step after melt spinning, but is not limited thereto. In the carbon fiber manufacturing step, a binding agent for preventing adhesion between fibers may be used, and surface treatment and sizing steps may be added after the carbonization step to improve adhesion to the matrix resin when manufacturing the composite material. In addition, the spinning conditions can be freely changed depending on the number of holes in the spinning machine or the capacity of the manufacturing facility.

Hereinafter, a method for manufacturing an isotropic pitch according to the present invention will be described in more detail through examples. In the following examples, each of the examples and comparative examples corresponds to an example for preferably carrying out the present invention, and the present invention is not limited thereto.

How to measure physical properties

1. Carbon and hydrogen atomic ratio (H/C)

Analysis with CHNS Elemental Analyzer

2. Aromatization degree (fa)

^{Analysis by 13} C NMR (ASTM D5292)

3. Raw materials and composition of raw materials

Analysis with 2D-GC

4. Average molecular weight (Mw)

The average molecular weight is analyzed by TOF-MS, and the average molecular weight of the pitch is analyzed by GPC.

5. Viscosity (Pa·s)

Viscosity is measured by TMA (Thermo Mechanical Analyzer)

6. Softening point (℃)

Softening point is measured by TMA (Thermo Mechanical Analyzer)

7. Yield

The yield was calculated by the weight of the finally obtained pitch relative to the weight of the added naphtha decomposition residue.

8. Mechanical properties

In order to calculate the tensile strength (GPa) and elongation (%), the stress-strain curve was measured with a UTM (Universal Test Machine) equipped with a 2N load cell for the carbon fiber sample. It was calculated from the diameter of the fiber analyzed by.

<Examples 1 to 4> and <Comparative Examples 1 to 3>

Naphtha Cracker Bottom Oil (NCBO) having the composition and degree of aromatization shown in Tables 1 to 2 below was prepared as a raw material.

carbon
(C, wt%) Hydrogen
(H, wt%) nitrogen
(N, wt%) Sulfur (S, wt%) H/C (atomic cost) 92.48 7.32 0.10 0.13 0.95

Aliphatic carbide (%) Aromatic carbide (%) Aromatization degree (fa) Methyl carbon
(CH3, Ar-CH3) Methylene carbon
(naphthalene) Unsubstituted carbon
(Ar-H) Quaternary carbon Substituted carbon
(Ar-C) 5.85 16.86 49.70 12.38 15.21 0.74

In Examples 1 to 4, prepared NCBO was pretreated by atmospheric distillation at 190°C, 200°C, 210°C, and 220°C, respectively, Comparative Example 1 was not pretreated, and Comparative Examples 2 to 3 were prepared NCBO at 150°C, respectively, Raw materials were produced by pretreatment at 250°C. The physical properties of the raw materials produced in the intermediate step according to each of the Examples and Comparative Examples are shown in Table 3 below.

Atomic ratio
(H/C) Degree of aromatization
(fa) Average molecular weight
(Mw) Comparative Example 1 0.95 0.74 170 Comparative Example 2 0.95 0.75 180 Example 1 0.95 0.78 195 Example 2 0.94 0.84 220 Example 3 0.94 0.86 245 Example 4 0.96 0.88 260 Comparative Example 3 0.94 0.91 295

The compositions of the compounds contained in the raw materials produced in the intermediate step according to each of the Examples and Comparative Examples are shown in Tables 4 to 7 below.

Pretreatment (℃) saturation
Carbide Aromatic ring
1 included
(Ar ₁ ) (% by weight) Aromatic ring
Includes 2
(Ar ₂ ) (% by weight) Aromatic ring
Includes 3
(Ar ₃ ) (% by weight) Aromatic ring
4 or more included
(Ar ₄ ) (% by weight) Total amount (%) Comparative Example 1 - 1.8 51.8 43.0 3.4 0.0 100 Comparative Example 2 150 1.6 48.3 46.3 3.8 0.0 Example 1 190 1.3 38.0 56.2 4.5 0.0 Example 2 200 1.3 30.0 61.4 7.3 0.0 Example 3 210 2.6 33.1 57.2 7.1 0.0 Example 4 220 1.8 30.2 59.7 8.3 0.0 Comparative Example 3 250 1.5 27.4 55.3 13.8 2.1

Pretreatment (℃) Compound containing one aromatic ring (% by weight) Alkyl benzene Alkenyl benzene Indan derivatives Indens Etc Total amount (%) Comparative Example 1 - 7.0 5.5 3.3 52.6 31.6 100 Comparative Example 2 150 5.7 0.0 4.2 54.1 36.0 Example 1 190 2.6 0.0 5.7 65.9 25.8 Example 2 200 8.3 0.0 13.3 56.7 21.7 Example 3 210 10.0 0.0 9.4 58.4 22.2 Example 4 220 8.4 0.0 11.7 44.3 35.6 Comparative Example 3 250 9.3 0.0 16.4 33.2 41.1

Pretreatment (℃) Compound containing two aromatic rings (% by weight) Biphenyls Naphthalene Etc Total amount (%) Comparative Example 1 - 0.5 62.5 37.4 100 Comparative Example 2 150 0.6 64.2 35.2 Example 1 190 0.7 85.3 14.0 Example 2 200 7.7 51.9 40.4 Example 3 210 6.0 53.2 40.8 Example 4 220 7.2 51.8 41.0 Comparative Example 3 250 14.8 33.7 51.5

Saturated hydrocarbon Aromatic ring
Includes 1 (% by weight) Aromatic ring
Includes 2 (% by weight) Aromatic ring
Three
Included (% by weight) Aromatic ring
4
More than
Included (% by weight) Total amount
(%) Alkylbenzene Alkenylbenzene Indanyu Indens Etc Biphenyls Naphthalene Etc Comparative Example 1 1.8 3.6 2.8 1.7 27.2 16.4 0.2 26.9 16.1 3.4 0.0 100 Comparative Example 2 1.6 2.8 0.0 2.0 26.1 17.4 0.3 29.7 16.3 3.8 0.0 100 Example 1 1.3 1.0 0.0 2.2 25.0 9.8 0.4 47.9 7.9 4.5 0.0 100 Example 2 1.3 2.5 0.0 4.0 17.0 6.5 4.7 31.9 24.8 7.3 0.0 100 Example 3 2.6 3.3 0.0 3.1 19.3 7.4 3.4 30.4 23.3 7.1 0.0 100 Example 4 1.8 2.5 0.0 3.5 13.4 10.8 4.3 30.9 24.5 8.3 0.0 100 Comparative Example 3 1.5 2.5 0.0 4.5 9.1 11.3 8.2 18.6 28.5 13.8 2.1 100

Thereafter, the raw material was filtered to remove the solid material, and then 100 parts by weight of the material was put into a metal container and heated at 370° C. for 0.5 hours. Thereafter, each was introduced into a thin film evaporator, and then heated in a vacuum atmosphere at 340° C. for 30 minutes to prepare an isotropic pitch. The average molecular weight, softening point, and viscosity of the prepared isotropic pitch are shown in Table 23.

<Examples 5 to 7> and <Comparative Examples 4 to 5>

Naphtha Cracker Bottom Oil (NCBO) having the physical properties of Table 8 and the compound compositions of Tables 9 to 12 was prepared as a raw material.

Atomic ratio (H/C) Aromatization degree (fa) Average molecular weight (Mw) Comparative Example 4 1.12 0.60 120 Example 5 0.96 0.74 170 Example 6 1.10 0.65 140 Example 7 0.93 0.80 220 Comparative Example 5 0.92 0.85 260

saturation
Carbide Aromatic ring
1 included
(Ar' ₁ ) (% by weight) Aromatic ring
Includes 2
(Ar' ₂ ) (% by weight) Aromatic ring
Includes 3
(Ar' ₃ ) (% by weight) Aromatic ring
4 or more included
(Ar' ₄ ) (% by weight) Total amount
(%) Comparative Example 4 2.3 62.4 33.2 2.1 0 100 Example 5 1.8 51.8 43.1 3.4 0 Example 6 1.7 59.8 35.7 2.8 0 Example 7 1.4 34.2 59.8 4.1 0.5 Comparative Example 5 1.5 29.6 56.3 8.4 4.2

Looking at Table 9, in each of the examples, Ar' ₁ is 34.2 to 51.8 (wt%)%, Ar' ₂ is 35.7 to 59.8 (wt%)%, Ar' ₃ is less than 4.1 (wt%)%, Ar' ₄ Belonged to less than 0.5 (% by weight)%. Among these content ratios, Ar' ₁ /Ar' ₂ was 0.57 to 1.67, Ar' ₃ /Ar' ₂ was 0.068 to 0.078, and Ar' ₁ /Ar' ₃ was 8.34 to 21.35.

Compound containing one aromatic ring (% by weight) Total amount
(%) Alkyl benzene Alkenyl benzene Indan derivatives Indens Etc Comparative Example 4 6.1 4.6 3.4 66.0 19.9 100 Example 5 6.9 5.4 3.3 52.7 31.7 Example 6 5.2 4.0 3.2 65.0 22.7 Example 7 8.5 6.7 6.1 31.0 47.7 Comparative Example 5 10.8 8.4 8.1 29.0 43.6

Compound containing two aromatic rings (% by weight) Total amount (%) Biphenyls Naphthalene Etc Comparative Example 4 1.2 34.0 64.8 100 Example 5 0.5 62.1 37.4 Example 6 0.3 35.0 64.7 Example 7 6.5 68.9 24.6 Comparative Example 5 11.5 73.7 14.7

Saturated carbide Aromatic ring
Includes 1 (% by weight) Aromatic ring
Includes 2 (% by weight) Aromatic
Includes 3 rings (% by weight) Aromatic ring
Including 4 or more (% by weight) Total amount
(%) Alkylbenzene Alkenylbenzene Indanyu Indens Etc Biphenyls Naphthalene Etc Comparative Example 4 2.3 3.8 2.9 2.1 41.2 12.4 0.4 11.3 21.5 2.1 0 100 Example 5 1.8 3.6 2.8 1.7 27.3 16.4 0.2 26.7 16.1 3.4 0 100 Example 6 1.7 3.1 2.4 1.9 38.9 13.5 0.1 12.5 23.1 2.8 0 100 Example 7 1.4 2.9 2.3 2.1 10.6 16.3 3.9 40.2 15.7 4.1 0.5 100 Comparative Example 5 1.5 3.2 2.5 2.4 8.6 12.9 6.5 41.5 8.3 8.4 4.2 100

In Table 12, in each example, the content of indenes among the main compounds is 10.6 to 38.9 (weight)%, the content of naphthalenes is 12.5 to 40.2 (weight)%, and the content of biphenyls is 0.1 to 3.9 (weight)% Belonged to. Among these content ratios (weight ratio), the weight of indenes/naphthalenes was 0.26 to 3.11, and the weight of biphenyls/naphthalenes was 0.007 to 0.094.

All prepared NCBOs corresponding to Examples 5 to 7 and Comparative Examples 4 to 5 were pretreated by atmospheric distillation at 200°C. The physical properties of the raw materials produced after pretreatment according to each of the Examples and Comparative Examples are shown in Table 13 below.

Atomic ratio
(H/C) Degree of aromatization
(fa) Average molecular weight
(Mw) Comparative Example 4 1.11 0.65 150 Example 5 0.94 0.84 220 Example 6 1.05 0.82 170 Example 7 0.93 0.86 250 Comparative Example 5 0.92 0.89 270

The composition of the compounds contained in the raw materials produced in the intermediate step according to each of the Examples and Comparative Examples are shown in Tables 14 to 17 below.

Saturated carbide Aromatic ring
1 included
(Ar ₁ ) (% by weight) Aromatic ring
Includes 2
(Ar ₂ ) (% by weight) Aromatic ring
Includes 3
(Ar ₃ ) (% by weight) Aromatic ring
4 or more included
(Ar ₄ ) (% by weight) Total amount
(%) Comparative Example 4 0.9 41.2 52.3 5.6 0 100 Example 5 1.3 30.0 61.4 7.3 0 Example 6 1.5 36.2 55.5 6.8 0 Example 7 1.2 22.5 66.6 7.4 2.3 Comparative Example 5 1.3 19.8 61.9 10.5 6.5

Compound containing one aromatic ring (% by weight) Alkyl benzene Alkenyl benzene Indan derivatives Indens Etc Total amount (%) Comparative Example 4 7.3 0 8.3 71.6 12.9 100 Example 5 8.3 0 13.3 56.7 21.6 Example 6 7.7 0 10.5 70.2 11.6 Example 7 13.8 0 20.9 40.4 24.9 Comparative Example 5 19.2 0 24.7 34.3 21.7

Compound containing two aromatic rings (% by weight) Biphenyls Naphthalene Etc Total amount (%) Comparative Example 4 8.0 27.3 64.6 100 Example 5 7.7 52.0 40.4 Example 6 6.8 39.1 54.1 Example 7 7.4 73.9 18.8 Comparative Example 5 12.6 76.0 11.4

Saturated hydrocarbons (% by weight) Aromatic ring
Includes 1 (% by weight) Aromatic ring
Includes 2 (% by weight) Aromatic
ring
Includes 3 (% by weight) Aromatic
ring
Including 4 or more (% by weight) Total amount (%) Alkylbenzene Alkenylbenzene Indanyu Indens Etc Biphenyls Naphthalene Etc Comparative Example 4 0.9 3.0 0.0 3.4 29.5 5.3 4.2 14.3 33.8 5.6 0.0 100 Example 5 1.3 2.5 0.0 4.0 17.0 6.5 4.7 31.9 24.8 7.3 0.0 100 Example 6 1.5 2.8 0.0 3.8 25.4 4.2 3.8 21.7 30.0 6.8 0.0 100 Example 7 0.9 3.1 0.0 4.7 9.1 5.6 4.9 49.2 12.5 7.4 2.3 100 Comparative Example 5 1.3 3.8 0.0 4.9 6.8 4.3 7.8 47.0 7.1 10.5 6.5 100

Thereafter, the raw material was filtered to remove the solid material, and then 100 parts by weight of the material was put into a metal container and heated at 370° C. for 0.5 hours. Thereafter, each was introduced into a thin film evaporator, and then heated in a vacuum atmosphere at 340° C. for 30 minutes to prepare an isotropic pitch. The average molecular weight, softening point, and viscosity of the prepared isotropic pitch are shown in Table 23.

Analysis of raw materials produced in the intermediate stage

Table 18 below shows the physical properties of the raw materials produced in the intermediate steps of all Examples and Comparative Examples.

Atomic ratio
(H/C) Degree of aromatization
(fa) Average molecular weight
(Mw) Comparative Example 1 0.95 0.74 170 Comparative Example 2 0.95 0.75 180 Example 1 0.95 0.78 195 Example 2 0.94 0.84 220 Example 3 0.94 0.86 245 Example 4 0.96 0.88 260 Comparative Example 3 0.94 0.91 295 Comparative Example 4 1.11 0.65 150 Example 5 0.94 0.84 220 Example 6 1.05 0.82 170 Example 7 0.93 0.86 250 Comparative Example 5 0.92 0.89 270

Referring to Table 18, in each example, the degree of aromatization was in the range of 0.78 to 0.88, and the average molecular weight was in the range of 170 to 260.

Tables 19 to 22 below show the compositions of compounds contained in the raw materials produced in the intermediate steps of all Examples and Comparative Examples.

Saturated carbide Aromatic ring
1 included
(Ar ₁ ) (% by weight) Aromatic ring
Includes 2
(Ar ₂ ) (% by weight) Aromatic ring
Includes 3
(Ar ₃ ) (% by weight) Aromatic ring
4 or more included
(Ar ₄ ) (% by weight) Total amount
(%) Comparative Example 1 1.8 51.8 43.0 3.4 0.0 100 Comparative Example 2 1.6 48.3 46.3 3.8 0.0 Example 1 1.3 38.0 56.2 4.5 0.0 Example 2 1.3 30.0 61.4 7.3 0.0 Example 3 2.6 33.1 57.2 7.1 0.0 Example 4 1.8 30.2 59.7 8.3 0.0 Comparative Example 3 1.5 27.4 55.3 13.8 2.1 Comparative Example 4 0.9 41.2 52.3 5.6 0 Example 5 1.3 30.0 61.4 7.3 0 Example 6 1.5 36.2 55.5 6.8 0 Example 7 1.2 22.5 66.6 7.4 2.3 Comparative Example 5 1.3 19.8 61.9 10.5 6.5

From Table 19 the content of the compound containing an aromatic ring in each embodiment is Ar ₁ is 22.5 ~ 38.0 (wt)%, Ar ₂ is 55.5 ~ 66.6 (wt)%, Ar ₃ is 4.5 ~ 8.3 (wt)%, Ar ₄ belonged to 0.0 to 2.3 (weight)%. Among these content ratios (weight ratio), Ar ₁ /Ar ₂ belonged to 0.33 to 0.67, Ar ₃ /Ar ₂ to 0.08 to 0.13, and Ar ₁ /Ar ₃ to 3.04 to 8.44.

Compound containing one aromatic ring (% by weight) Total amount
(%) Alkyl benzene Alkenyl benzene Indan derivatives Indens Etc Comparative Example 1 7.0 5.5 3.3 52.6 31.6 100 Comparative Example 2 5.7 0.0 4.2 54.1 36.0 Example 1 2.6 0.0 5.7 65.9 25.8 Example 2 8.3 0.0 13.3 56.7 21.7 Example 3 10.0 0.0 9.4 58.4 22.2 Example 4 8.4 0.0 11.7 44.3 35.6 Comparative Example 3 9.3 0.0 16.4 33.2 41.1 Comparative Example 4 7.3 0 8.3 71.6 12.9 Example 5 8.3 0 13.3 56.7 21.6 Example 6 7.7 0 10.5 70.2 11.6 Example 7 13.8 0 20.9 40.4 24.9 Comparative Example 5 19.2 0 24.7 34.3 21.7

Compound containing two aromatic rings (% by weight) Total amount
(%) Biphenyls Naphthalene Etc Comparative Example 1 0.5 62.5 37.4 100 Comparative Example 2 0.6 64.2 35.2 Example 1 0.7 85.3 14.0 Example 2 7.7 51.9 40.4 Example 3 6.0 53.2 40.8 Example 4 7.2 51.8 41.0 Comparative Example 3 14.8 33.7 51.5 Comparative Example 4 8.0 27.3 64.6 Example 5 7.7 52.0 40.4 Example 6 6.8 39.1 54.1 Example 7 7.4 73.9 18.8 Comparative Example 5 12.6 76.0 11.4

Saturated hydrocarbon Aromatic ring
Includes 1 (% by weight) Aromatic ring
Includes 2 (% by weight) Contains 3 aromatic rings (% by weight) Aromatic ring
Including 4 or more (% by weight) Total amount
(%) Alkylbenzene Alkenylbenzene Indanyu Indens Etc Biphenyls Naphthalene Etc Comparative Example 1 1.8 3.6 2.8 1.7 27.2 16.4 0.2 26.9 16.1 3.4 0.0 100 Comparative Example 2 1.6 2.8 0.0 2.0 26.1 17.4 0.3 29.7 16.3 3.8 0.0 100 Example 1 1.3 1.0 0.0 2.2 25.0 9.8 0.4 47.9 7.9 4.5 0.0 100 Example 2 1.3 2.5 0.0 4.0 17.0 6.5 4.7 31.9 24.8 7.3 0.0 100 Example 3 2.6 3.3 0.0 3.1 19.3 7.4 3.4 30.4 23.3 7.1 0.0 100 Example 4 1.8 2.5 0.0 3.5 13.4 10.8 4.3 30.9 24.5 8.3 0.0 100 Comparative Example 3 1.5 2.5 0.0 4.5 9.1 11.3 8.2 18.6 28.5 13.8 2.1 100 Comparative Example 4 0.9 3.0 0.0 3.4 29.5 5.3 4.2 14.3 33.8 5.6 0.0 100 Example 5 1.3 2.5 0.0 4.0 17.0 6.5 4.7 31.9 24.8 7.3 0.0 100 Example 6 1.5 2.8 0.0 3.8 25.4 4.2 3.8 21.7 30.0 6.8 0.0 100 Example 7 0.9 3.1 0.0 4.7 9.1 5.6 4.9 49.2 12.5 7.4 2.3 100 Comparative Example 5 1.3 3.8 0.0 4.9 6.8 4.3 7.8 47.0 7.1 10.5 6.5 100

Table 22 shows that most of the alkenylbenzene was volatilized from the raw material through the pretreatment process of the naphtha cracking residue, and the contents of alkylbenzene and phosphorus were reduced as a whole. On the other hand, compounds containing indans, biphenyls, and three or more aromatic rings increased slightly overall, and the content of naphthalenes increased significantly. In each example, the contents of the main compounds of the raw material were all volatilized to the extent that alkenylbenzene was not measured, indans were 2.2 to 4.7 (wt)%, indenes were 9.1 to 25.4 (wt)%, biphenyls Was in the range of 0.4 to 4.9 (weight)%, and naphthalenes in 21.7 to 49.2 (weight)%. And, in each example, the ratio of the main compound content of the raw material was the ratio of indenes and naphthalenes (indenes/naphthalenes) was 0.18 to 1.17, and the weight ratio of biphenyls and naphthalenes (biphenyls weight/naphthalenes) Flow weight) was in the range of 0.08 to 0.13.

Manufactured Isotropic pitch Property analysis

Table 23 below shows the physical properties of the isotropic pitch prepared according to all Examples and Comparative Examples.

Softening point (℃) Average molecular weight (Mw) Viscosity (Pa·s) Comparative Example 1 265 1350 375 Comparative Example 2 263 1400 382 Example 1 265 1750 411 Example 2 260 2200 342 Example 3 265 2350 194 Example 4 260 2500 360 Comparative Example 3 270 2950 445 Comparative Example 4 260 1500 289 Example 5 265 2200 342 Example 6 263 1800 324 Example 7 269 2500 368 Comparative Example 5 280 2800 402

Referring to Table 23, the softening point of each example was 265 to 269°C, the average molecular weight belonged to 1750 to 2500, and the viscosity belonged to 194 to 411.

Isotropic pitch Carbon fiber Whether melt spinning is possible Single yarn frequency Diameter (㎛) Tensile strength (GPa) Elongation(%) Comparative Example 1 O 0 7.40 0.7 2.5 Comparative Example 2 O 0 7.60 1.1 2.6 Example 1 O 0 8.10 2.0 2.3 Example 2 O 0 7.30 1.7 2.3 Example 3 O 0 6.80 1.6 2.9 Example 4 O 0 7.10 1.5 2.1 Comparative Example 3 0 0 8.70 0.9 1.5 Comparative Example 4 O 7 times 6.89 0.8 2.8 Example 5 O 0 7.34 1.7 2.3 Example 6 O 0 7.02 1.5 2.1 Example 7 O 0 8.21 1.6 2.2 Comparative Example 5 0 5 times 8.32 1.1 1.9 Single yarn frequency is measured as the frequency of interruption during continuous spinning for 20 minutes

Referring to Table 24, all of the examples were melt-spun, and no single yarn was generated during spinning, and the tensile strength of the carbon fiber was at least 1.5 GPa and the elongation was 2% or more. On the other hand, in the comparative example, melt spinning was possible, but there was a single yarn, and even if a single yarn did not occur, the elongation was less than 2.0% or the tensile strength of the carbon fiber was at most 1.1 GPa, showing a remarkable difference in strength from the example.

Claims (13)

(a) preparing raw materials satisfying the following formulas (1) to (4) by pretreating a raw material containing at least one or more of naphtha decomposition residue oil, petroleum heavy oil, or coal tar fraction at 160 to 240°C. ; And
20.0% by weight ≤ Ar ₁ ≤ 45.0% by weight --- (1)
50.0% by weight ≤ Ar ₂ ≤ 70.0% by weight --- (2)
0.0% by weight ≤ Ar ₃ ≤ 10.0% by weight --- (3)
0.30 <Ar ₁ /Ar ₂ <0.75 --- (4)
(b) thermally polymerizing and heating the raw material prepared in (a);
Method for producing an isotropic pitch comprising a.
(The Ar ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, the Ar ₂ is the content of the compound containing two aromatic rings relative to _{the total amount of the raw material, and Ar 3} is three aromatics relative to the total amount of the raw material. It is the content of the compound containing the ring.) The method of claim 1,
The raw material is a method of producing an isotropic pitch satisfying 20.0% by weight ≤ naphthalenes ≤ 60.0% by weight and 0.0% by weight ≤ biphenyls ≤ 5.0% by weight relative to the total amount. The method of claim 2,
The raw material is a method of producing an isotropic pitch satisfying the weight of biphenyls / weight of naphthalenes <0.20. The method of claim 1,
The raw material is a method for producing an isotropic pitch that satisfies _{Ar 4 ≤5.0% by weight.}
(The Ar ₄ is the content of a compound containing four or more aromatic rings relative to the total amount of the raw material.) The method of claim 1,
The raw material is Ar ₃ /Ar ₂ Method for producing an isotropic pitch satisfying <0.15. The method according to any one of claims 1 to 5,
The raw material containing at least one or more of the naphtha decomposition residue oil, petroleum-based heavy oil, or coal tar oil is a method for producing an isotropic pitch satisfying the following formulas (1) to (5).
30.0% by weight ≤ Ar' ₁ ≤ 60.0% by weight --- (1)
55.0% by weight ≤ Ar' ₂ ≤ 70.0% by weight --- (2)
0.55 <Ar' ₁ /Ar' ₂ <1.75 --- (3)
0.0% by weight ≤ Ar' ₃ ≤ 5.0% by weight --- (4)
0.0% by weight ≤ Ar' ₄ ≤ 3.0% by weight --- (5)
(The Ar' ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, the Ar' ₂ is the content of the compound containing two aromatic rings relative to the total amount of the raw material, and Ar' ₃ Is the content of the compound containing three aromatic rings relative to the total amount of the raw material, and Ar' ₄ is the content of the compound containing four or more aromatic rings relative to the total amount of the raw material.) The method of claim 6,
The raw material is a method for producing an isotropic pitch satisfying 10.0% by weight of the total amount of ≤ indenes ≤ 40.0% by weight and 10.0% by weight ≤ naphthalenes ≤ 45.0% by weight. The method of claim 7,
The raw material is a method for producing an isotropic pitch that satisfies 0.25<weight of indenes/weight of naphthalenes<3.50. delete delete delete The method according to any one of claims 1 to 5,
The isotropic pitch is a method of producing an isotropic pitch having a softening point of 250°C to 280°C. As a raw material for producing an isotropic pitch satisfying the following formulas (1) to (7) by heat treatment and fractionation of a raw material containing at least one of naphtha decomposition residues, petroleum heavys, or coal tar oil, the isotropic pitch is melted. Raw material for producing isotropic pitch which is spinnable and has a softening point of 250 to 280°C.
20.0% by weight ≤ Ar ₁ ≤ 45.0% by weight --- (1)
50.0% by weight ≤ Ar ₂ ≤ 70.0% by weight --- (2)
0% by weight ≤ Ar ₃ ≤ 10.0% by weight --- (3)
20.0% by weight ≤ naphthalenes ≤ 60.0% by weight --- (4)
0% by weight ≤ biphenyls ≤ 5.0% by weight --- (5)
0.30 <Ar ₁ /Ar ₂ <0.75 --- (6)
Weight of biphenyls/weight of naphthalenes <0.20 --- (7)
(The Ar ₁ is the content of the compound containing one aromatic ring relative to the total amount of the raw material, the Ar ₂ is the content of the compound containing two aromatic rings relative to the total amount of the raw material, and Ar ₃ contains three aromatic rings relative to the total amount of the raw material Is the content of the compound, in the formulas (4) and (5), naphthalenes and biphenyls are content relative to the total amount of raw materials, and in the formula (7), the weight of biphenyls/naphthalenes is based on the weight of naphthalenes. It is the weight ratio of biphenyls.)

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