WO2015076534A1 - Isotropic pitch for manufacturing carbon fiber and method for preparing same - Google Patents

Abstract

The present invention relates to an isotropic pitch for manufacturing a carbon fiber and a method for preparing the same, wherein an isotropic pitch having particular ranges of a softening point, viscosity, a molecular weight, and a crystal structure can be prepared, and such a feature can maximize mechanical properties of the carbon fiber by maximally suppressing the generation of insoluble solids and mesophase of the pitch, and can also reduce energy consumption since a carbonization process is performed at a low temperature.

Description

 [Hostess]

 [Name of invention]

 Isotropic pitch for producing carbon fiber and its manufacturing method

 Technical Field

 The present invention relates to an isotropic pitch for producing carbon fibers and a method for manufacturing the same. Specifically, the present invention relates to an isotropic pitch having a specific range of physical properties and structure, and is used to prepare carbon fibers having high strength and high elasticity compared to conventional isotropic carbon fibers. It relates to an isotropic pitch and a method for producing the same.

[Background Art] ^"

<2> Low fuel consumption of automobiles is increasingly required due to exhaustion of petroleum resources, price hikes and environmental issues. According to the Working Group's report, energy efficiency is expected to increase by more than 600% by 2020. The most effective is the hybridization of the engine, followed by the improvement of the engine efficiency, the weight of the car body, and the efficiency of energy transfer. It is said to work. In particular, according to the US Department of Energy. Reducing the body weight by 10% reduces fuel consumption by approximately 7%, which requires more technical development to reduce the weight of the body.

 <3> Body weight reduction can also be achieved by the use of high strength steels, aluminum alloys, etc., but carbon fiber reinforced plastics are highly effective, and engine hoods, propeller shafts and hydrogen tanks in automobiles. The trend is already in use. When CFRP is used as the main material of the body structure, weight reduction of about 50% is possible, and the impact energy absorption performance is also improved. Best of all, the lightest car bodies available today can be manufactured, and research is being conducted around the world.

 <4> However, CFRP also has a weak point. Tensile strength is weak compared to compression, and interlayer separation is likely to occur due to lamination. After impact, the compressive strength is drastically reduced. In addition, there is a disadvantage that the manufacturing cost is expensive, many applications are difficult. .

 <5> In general, the carbon fibers included in CFRP may be classified into rayon, PAN, and pitch based on precursors. Among them, liquid crystal pitch based carbon fibers and isotropic pitch based on pitch types of precursors It can be divided into carbon fiber. In addition, isotropic pitch-based carbon fiber is called general-purpose carbon fiber because it has lower price than high performance grade, and it is produced in staple type carbon island channel by melt blown method, so it can be used as high temperature insulation material or filter. It is used as activated carbon fiber.

[6] There are many advantages to producing carbon fibers from petroleum, coal tar, or chemical pitches. One of the reasons is the high carbon-to-hydrogen ratio of these raw materials. All. For example, the theoretical yield of carbon fiber produced from PAN resin is about 50%, while the theoretical yield of carbon fiber produced from well-purified pitch reaches 90%. However, pitch-based carbon fibers with striking tensile strength and modulus that can be used as composites in aerospace, aerospace, etc. are manufactured from liquid crystal pitches. To prepare liquid crystal pitches from petroleum, coal tar, or chemical pitches, pretreatment, hydrogenation, Complex processes such as the separation of quinoline insolubles are required, and thus, there is a disadvantage that the production cost increases and the price is high.

Conventional techniques related to isotropic pitch-based carbon fibers or isotropic pitches for producing carbon fibers include Korean Patent Laid-Open Publication No. 10-2013-0059174, Japanese Patent Laid-Open Publication No. 1996-144131, and the like. 10-2013—0059174 describes a method for preparing a precursor for carbon fibers having a high softening point, but partially melted solids or mesophases are formed at a pitch heating temperature of 360 ^° C. or higher, resulting in carbon produced. There is a disadvantage of poor physical properties of the fiber.

In addition, Japanese Patent Application Laid-Open No. 1996-144131 claims a round pitch for producing carbon fibers having a specific molecular weight, but has a low softening point of 180 to 200 ^° C. and a tensile strength of the carbon fiber prepared from the pitch. Its strength is 89.3 kg / mitf (approximately 0.893 GPa) and shows low physical properties to be used for CFRP purposes for automotive steel plates.

As such, there is a strong demand for the development of carbon fiber manufacturing technology using isotropic pitches that satisfy all the necessary properties that can be used for CFRP and can be mass-produced at low production costs.

 <ιο> "(Patent Document 1) Republic of Korea Patent Publication No. 2013-0059174 (June 05, 2013)"

<ι ι> `` (Patent Document 2) Japanese Patent Laid-Open Publication 1996-144131 (June 04, 1996) ''

 [Detailed Description of the Invention]

 [Technical problem]

 The present inventors conducted a study to solve the above problems, and as a result, invented a method for producing an isotropic pitch having a specific range of physical properties, molecular structure and laminated structure, the isotropic pitch prepared from the conventional isotropic carbon fiber It can be used to make carbon fibers with superior mechanical properties.

 Technical Solution

 <13> The present invention is the average diameter of the laminated structure formed by the condensed aromatic ring compound layer

(L _c ), the average distance between condensed aromatic ring compound layers in the laminated structure (dj, the average diameter of the condensed aromatic ring compound layer (L _a ), the average of aliphatic chains connected to the condensed aromatic ring compound An isotropic pitch is provided that includes a structure represented by an average number (M) of condensed aromatic ring compound layers included in the laminated structure, which can be represented by distance (d _Y ) and (L _c / d _m ) + l. <14> The present invention is a pre-treatment of any one or a mixture of petroleum heavy oil, high-boiling residue, aromatic hydrocarbon mono- and naphtha cracking process residue to produce a raw material, in the raw material prepared It provides a filtration step of removing the solid material, polymerizing the filtered raw material to produce a basic pitch, and heating the basic pitch to produce the isotropic pitch.

 Advantageous Effects

 The round pitch of the present invention has a softening point and a molecular weight in a specific range, and the generation of insoluble solids and mesophase is suppressed to the maximum in the pitch, so that the spinning property is excellent, the elongation is high, and the tensile strength is remarkably high. Increased to provide isotropic pitch-based carbon fibers that can be used for carbon composite applications.

 [Brief Description of Drawings]

 1 is a flowchart of a carbon fiber manufacturing process according to a preferred embodiment of the present invention. FIG. 2 is an X-ray diffraction analysis of isotropic pitch in a manufacturing method including a halogenation step.

 <! 8> X-ray diffraction analysis of the isotropic pitch in the manufacturing method including the thermal polymerization step.

4 is an isotropic pitch structure analysis through X-ray diffraction analysis, where d 'is the average distance between condensed aromatic ring compounds in the laminated structure, and ^ is the average distance between aliphatic chains connected to the condensed aromatic ring compound. L _c is the average diameter of the laminated structure formed by the condensed aromatic ring compound layer, L _a is the average diameter of the condensed aromatic ring compound layer, and M is the average number of the condensed aromatic ring compound layers included in the laminated structure. to be.

 <20>

 [Form for implementation of invention]

Hereinafter, an isotropic pitch for producing carbon fibers and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided as examples in order to enable those skilled in the art to fully convey the spirit of the present invention. Therefore, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. Also, like reference numerals designate like elements throughout the specification. Represents the elements.

 In this case, unless there is another definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs, the present invention in the following description and the accompanying drawings Descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter may be omitted.

 The present invention relates to an isotropic pitch for producing carbon fibers, in which a layer of condensed aromatic cyclic compounds forms a laminated structure. Provided is an isotropic pitch for producing carbon fibers and a method for producing the same, wherein the condensed aromatic ring compound is linked with an aliphatic chain.

 The isotropic pitch of the present invention is excellent in spinning property, so that melt spinning is possible. No single yarn is generated or extremely rare during spinning, and the carbon fiber prepared therefrom has maximized physical properties of high strength and high elasticity.

 First, the isotropic pitch of the present invention will be described in detail.

 In the isotropic pitch of the present invention, the gamma band (γ-band) of the al iphat ic chain is found at 17 <2 θ <18 in X-ray diffraction (XRD). It is an isotropic pitch that includes a structure in which a (002) plane band appears at 23 <2θ <25 and a (10) band appears at 43 <2θ <45, where the condensed aromatic ring compound is connected by an aliphatic chain.

 The above structure has an average diameter of the laminated structure formed by the condensed aromatic ring compound layer.

(L _c ), the average diameter of the condensed aromatic ring compound layer (L, the lamination structure represented by the average distance (d ,,,) and (L _c / d ,,,) + l between the condensed aromatic ring compound layers in the laminated structure. It can be described as the average number of condensed aromatic ring compound layers (M) in the structure, and the average distance between aliphatic chains connected by condensed aromatic ring compounds and connected to the condensed aromatic ring compound (M). The condensed aromatic ring compound may be different depending on the condensed structure but includes at least 2 to 7 aromatic rings, and the condensed aromatic ring compound layer is preferably aromatic. It may be a layer consisting of a compound in which the rings are condensed or a compound layer containing a condensed aromatic ring compound, which may be connected by an aliphatic chain. In addition, the laminated structure formed by the condensed aromatic Chora compound layer may be expressed as a nano cluster, and each measurement result of the crystal structure may be represented by XRD measurement results, Bragg equations, and scherrer equations. Can be represented by

 Specifically, the average diameter of the laminated structure formed by the condensed aromatic ring compound layer

(L _c ) is 10 to 25, preferably 15 to 20, and the level of the condensed aromatic ring compound layer Average diameter (LJ is 5 to 15, preferably 8 to 12, and average distance between condensed aromatic ring compound layers in a laminated structure (dj is 3.50 to 4.50, preferably 3.55 to 4.00, and an aliphatic linked to the condensed aromatic ring compound The average distance between chains (^) is from 4.50

5.50, preferably 4.80 to 5.20, and the average number (M) of condensed aromatic ring compound layers included in the laminated structure is 4.00 to 8.00, preferably 5.00 to 7.00. <29> The isotropic pitch prepared in the present invention has excellent radioactivity only when the structure satisfies the above range, and there is a very small amount such that non-fused solids and mesofaces are not produced or measured, and the mechanical properties of the carbon fiber produced therefrom This can be maximized. If it is out of the above range, an unfused solid and mesophase may be formed and frequent single yarns may occur during spinning, and the tensile strength of the carbon fiber produced therefrom may be significantly reduced or the elongation f ^ΰΙ may be too low or too high, resulting in poor elastic modulus.

 The isotropic pitch of the present invention can be expressed as follows according to the analysis result.

In the X-ray diffraction analysis, the round pitch of the present invention has a (002) plane band at 23 <2 Θ <25, and the following formulas (1) to (4) in which the condensed aromatic ring compound is connected with an aliphatic chain It is an isotropic pitch for producing carbon fiber with a satisfactory structure.

<32> 5 <L _a <15 A-(1)

<33> 10 <L _c <25 A-(2)

_{<34> 3.50 <d m <} 4.50A - (3) '

 <35> 4.00 <M <8.00 A-(4)

 According to one embodiment of the present invention, even if the above formulas (1), (2) and (3) are satisfied, if the content of (4) is not satisfied, the molecular weight of the isotropic pitch is too small, and thus the objective of the isotropic pitch of the present invention It does not satisfy the tensile strength of the carbon fiber, the elongation is too high, the elastic modulus falls. According to another embodiment of the present invention, even if the above formulas (2) and (3) are satisfied, if (1) and (4) are not satisfied, frequent single yarns occur during spinning of the isotropic pitch, and the carbon fiber manufactured therefrom The tensile strength of is significantly reduced and the elongation is also lowered. According to another embodiment of the present invention, if the formulas (1) and (3) are satisfied, but not satisfying (2) and (4), the molecular weight of the isotropic pitch is not only low, but also Tensile strength is significantly reduced.

The isotropic pitch may be represented in more detail by further expressing an average distance dy between aliphatic chains connected to the condensed aromatic ring compound in the structure included in the isotropic pitch. In the formulas (1) to (4) and the average distance (d _Y ) between the aliphatic chains linked to the condensed aromatic ring compound of the present invention, an isotropic pitch having better physical properties and radioactivity The mechanical properties of the high strength and high elasticity of the isotropic pitch-based carbon fiber can be produced and can be further maximized.

The isotropic pitch softening point of the present invention is 255 to 275 ^° C., preferably 260 to

270 ^° C and, even if the softening point is too low or too high field above a certain length of the radiation is difficult or radiation over a certain length of the fibers falls the uniformity of the shape, diameter, etc. are not uniform the vulnerable fibers made in physical properties terms of tensile strength Can be.

The isotropic pitch average molecular weight (Mw) of the present invention is 1500 to 3000, preferably

1650 and 2850. Isotropic pitches having an average molecular weight in the above preferred range can significantly increase the tensile strength in the production of carbon fibers and further increase the elongation rate.

 According to one embodiment of the present invention, the isotropic pitch viscosity is 200 to 500, but may be appropriately adjusted according to the method of producing carbon fibers.

 Next, the manufacturing method of the isotropic pitch for carbon fiber manufacture of this invention is demonstrated in detail.

 <43> The method for producing the isotropic pitch for producing carbon fibers of the present invention,

 A) a pretreatment step of thermally treating and fractionating a raw material including any one or a combination thereof selected from petroleum heavy oil, high boiling residue, aromatic hydrocarbon monomaterial and naphtha cracking process residue;

 B) a filtration step of removing solid matter from the pretreated raw material;

 C) preparing a basic pitch from the filtered raw material; And

D) heating the basic pitch to produce an isotropic pitch _. step;

 It is a method for producing an isotropic pitch for producing carbon fibers including <48>.

 The filtration step of b) in the above manufacturing method may be performed even after preparing the basic pitch of C), and the basic pitch of C) is an intermediate material for producing an isotropic pitch. Physical properties may vary.

 More specifically, the raw material may include pyrolysis fuel oil (PF0), which is a kind of naphtha decomposition residue oil. PF0 is produced at the bottom (bottom) of the naphtha cracking center (NCC) and has a high degree of aromaticity and abundant resin, which can be used as a raw material of the present invention.

<5 i> Pyrolysis fuel oil is produced at the bottom of the naphtha cracking process. Aromatic hydrocarbons. Specific examples of the aromatic hydrocarbon is ethyl benzene (ethylbenzene), 1-butenyl eu eu 3-methylbenzene _{(l- e thenyl-3- methyl benzene} ), indene (Indene), 1-ethyl-3-methylbenzene (l -ethyl-3-methyl benzene), 1-methylethyl benzene, 2-ethyl-1,3-dimethylbenzene, 2-dime (hyl benzene), propylenebenzene ( propyl benzene), 1-methyl-4- (2-propenyl) -benzene (l-methyl-4- (2-propenyl) benzene), 1,1a, 6, 6a-tetrahydro-cyclopropanedene (1 , La ， 6 ， 6a-tetrahydro-cycloprop [a] i ndene), 2-ethyl— 1H-indene (2-et hy 1-1H- i ndene), 1-methyl-1H-indene (1-methyl-lH -indene), 4, 7-dimethyl-lH-indene (4, 7-dimethyl-lH-indene), 1-methyl-9H-fluorene, 1,7-dimethyl naphthalene (1, 7-dimethyl naphthalene, 2-methyl indene, 4,4'-dimethyl bihenyl, naphthalene, 4-methyl-1, 1 ' ᅳ biphenyl (4-methyl_l, Γ -biphenyl) ， anthracene

(Anthracene), 2-methylnaphthalene, 1-methylnaphthalene, and the like.

 Raw material according to an embodiment of the present invention may further include a high boiling point oil. The high boiling fraction according to an embodiment of the present invention refers to a component having a high boiling point and a high carbon number among components that can be obtained by fractional distillation of crude oil, and mainly a hard or heavy aromatic naphtha having 5 or more carbon atoms, preferably 7 or more carbon atoms. May include

 More specifically, the high boiling point oil may include an oil having 9 carbon atoms. Specifically, for example, it may be made of styrene, vinyltoluene, indene, alphamethylstyrene and benzene / luluene / xylene (BTX).

 The oil having 9 carbon atoms may preferably include indene. Indene is combined with the side chain of the aromatic component in the raw material to prevent the tendency to dehydrate and etherify as the side chain of the aromatic component is oxidized in the stabilization step after melt spinning, resulting in lowering carbonization temperature and time. Can contribute.

<55> _. The high boiling fraction is preferably contained in an amount of 5 to 15% by weight based on 100% by weight of the total raw material. If the content is less than 5% by weight, the effect may be insignificant. The effect may not be obvious

 The degree of aroma (fa) of the raw material may be 0.7 to 0.9. If the degree of aroma is less than 0.7, the carbonization yield may be lowered. There is no particular limitation on the case where the aromaticity is higher than 0.9, but when the aromaticity is 0.9 or more, the effect by the series of pitch synthesis methods disclosed in the present invention may not be significant.

The molecular weight of the raw material may have a distribution of 75 to 350, and preferably may have a distribution of 100 to 250. In the method for producing the isotropic pitch, step _a ) removes low molecular weight substances that are less likely to form oligomers by a polymerization reaction among the compounds included in the raw material, and simultaneously reacts reactions between the compounds contained in the raw material. This is a step of converting a highly reactive and unstable compound contained in the raw material into a more stable and effective compound for producing isotropic pitch.

In step a), the pretreatment may be carried out by atmospheric distillation at a temperature of 130 to 240 ^° C., preferably 150 to 230 ^° C., more preferably 190 to 220 ^° C. until no volatiles are generated. have. In the pretreatment, the heating temperature can affect the physical properties of the basic pitch and isotropic pitch, such as the composition ratio of the raw materials and the degree of aroma, and also the mechanical properties of the carbon fibers. In addition, the pretreatment step may proceed at atmospheric pressure, but may proceed under reduced pressure. At this time, the pretreatment process may be performed at a lower temperature through decompression, and the pressure and temperature may be freely adjusted within a range capable of obtaining the same effect as the normal pressure.

 In the manufacturing method of the isotropic pitch, step b) is a filtration step of the pretreated fuel to remove the solid material, and the solid material is a residue of a solid phase containing impurities such as metal, sulfur, and nitrogen from the isotropic pitch. It can act as a cracker in the structure of the carbon fiber to be produced may cause a decrease in strength.

 Filtration may be carried out in a manner conventionally performed in the art, for example, by filtration, centrifugation, sedimentation, adsorption, extraction, etc.

<62> filtration step may also be performed after the polymerization of the basic pitch ^diameter: Yiwu thus is the pre-treatment step may be carried out all of the following basic pitch and polymerization steps. That is, the manufacturing method may be performed after step (c), and in some cases, may be performed after steps (a) and (c), respectively.

 In the method for producing the isotropic pitch, step C) is a basic pitch manufacturing step, in which a raw pitch having a high softening point is produced without generating mesophases by heating the raw material that has undergone the filtration step at the same time. It can proceed by law or thermal polymerization.

 The halogenation method may proceed by heating after further adding a halogen compound and a radical initiator, and preferably by adding and mixing a halogen compound after the addition of the radical initiator.

Halogenated compounds are chlorine (Cl ₂ ), thionyl chloride (S0C 1 ₂ ), sulfuryl chloride

Group consisting of (S0 ₂ C1 ₂ ), brm (Br ₂ ), iodine (1 ₂ ) or a combination of two or more thereof Selected from among them may be used.

<66> radical initiator is benzoyl peroxide (B _enZ0 yi peroxide), di-butyl hydroperoxide oxazol id (di-t-butyl hydroperoxide) , acetyl peroxide (Acetyl peroxide) such yugigwa oxide (Organi c Peroxide) and, Azo Azo compounds such as bisisobutyronitrile (AIBN; α, α '-Azobisisobutyroni tr ile), azobismethylisobutylate (α, a' -Azobi smethyl i sobutyrate), or a group consisting of a combination of two or more of these The one selected from can be used.

 The radical initiator may be included in an amount of 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the halogen compound.

Halogenation is carried out by halogenation reaction at 100 to 12 (0.5 to 2 hours ^at C to replace hydrogen in the aromatic alkyl group with halogen, followed by polymerization by dehalogenation reaction at 300 to 330 ^° C. for 2 to 4 hours. In addition, the dehalogenation reaction can further enhance the purity of the basic pitch produced by decomposing halogen compounds and radical initiators that may remain in the basic pitch after the reaction, particularly in the dehalogenation reaction. banung temperature is good is not more than 330 ^° C, 330 ^° C in excess of, the process advances upset anisotropic screen or coking of the basic pitch of the excess polymerization only occurs actively decomposition of the halogenated compound and a radical initiator as a result of the carbon fiber machine Physical properties are greatly reduced.

According to one embodiment of the present invention, the basic pitch prepared by the halogenation method may have a softening point of 70 to 130 C, preferably 115 to 125 ^° C.

Thermal polymerization can be carried out at 350 to 380 ^° C. for 0.1 to 2 hours. The thermal polymerization method may proceed in an inert gas atmosphere, and may proceed by fractionating gaseous by-products generated during the process of nitrogen and polycondensat ion. In the thermal polymerization method, as in the halogenation method, the reaction temperature should not exceed 380 ^° C. However, when the reaction temperature exceeds 380 ^° C, the reaction temperature exceeds the range of uniform anisotropy pitch for the present invention, as in the halogenation method. Excess mesophase may be produced or coking may result in uneven carbon fibers.

The basic pitch prepared by the thermal polymerization method may have a softening point of 85 to 140 ^° C., preferably 115 to 125 ^° C.

In the manufacturing process of the isotropic pitch, the physical properties of the basic pitch can be adjusted according to the configuration convenience. For example, when the process is configured for the purpose of smoothly flowing the fluid flowing in the step (c) to the step (d) of the manufacturing method, the condensation aromatics of the basic pitch manufactured from the step (c) To the absolute amount of the ligomer linked to the ring compound It may further include a compound having a low boiling point in a range that does not significantly affect. This effect can be obtained when step (c) is carried out under pressurization, where the ^' softening point of the basic pitch is applied to the physical properties, molecular structure and laminated structure of the isotropic pitch that is finally manufactured according to the convenience of the process configuration. You can freely adjust the range without affecting it.

 In the manufacturing method of the isotropic pitch, step d) may be a process of manufacturing isotropic pitch capable of suppressing mesophase generation by promoting evaporation by heating the basic pitch as an isotropic manufacturing step.

 The isotropic pitch manufacturing step may proceed with a conventional thin film distillation method, and thus, there is an advantage that an additional process of suppressing the formation of mesophase and removing insoluble solids is not necessary. In addition, the isotropic pitch manufacturing step according to an embodiment of the present invention may correspond to the composition and state change of the isotropic pitch manufactured with a multi-stage thin film distillation apparatus.

The isotropic pitch manufacturing step may be performed by heating in a vacuum atmosphere for 0.1 to 1 hour at 300 to 350 ^° C. In particular, when the heating temperature exceeds 350 ^° C., meso phases are partially formed, and insoluble carbon solids may be generated by the continuous heating, and it is preferable to observe the heating temperature and the heating time.

Isotropic pitch according to an embodiment of the present invention may have a softening point of 255 to 275 ^° C, preferably 260 to 270 ^° C. In addition, the isotropic pitch average molecular weight (Mw) of the present invention may be 1500 to 3000, preferably 1700 to 2850. Since the average molecular weight and softening point of the isotropic pitch can greatly affect the physical properties of the carbon fibers to be produced, it is preferable to comply with the manufacturing process conditions.

The isotropic pitch produced in the present invention is capable of melt spinning, and does not have single yarn or extremely rare spinning when spinning. Melt spinning is a method of melting polymer materials or pitches into continuous fibers, eliminating the need for expensive solvents for spinning, and simplifying the construction of spinning processes and significantly reducing costs. Way. In order to enable the melt spinning for the production of carbon fibers, pitch spinning should be excellent, but the isotropic pitch prepared according to the present invention has very good spinning property, and melt spinning for carbon fiber manufacturing is possible, but the single yarn is extremely rare. Does not happen. In addition, the isotropic pitch capable of melt-spinning of the present invention has a very high radioactivity compared to the isotropic pitch which was used to produce short fibers through melt-blowing, and thus it has high strength and high elastic carbon long fibers. It can also be manufactured. According to one embodiment of the present invention, as a result of measuring the isotropic pitch for 20 minutes in a row with the frequency of melt spinning off as a single shot frequency, it can be seen that the single yarn frequency corresponds to 0, which is very excellent in radioactivity.

In addition, the isotropic pitch of the present invention can be carbonized at a low temperature of 700 to 1200 ^° C or less to minimize the energy consumption during the carbonization process.

 The isotropic pitch prepared according to the present invention may produce carbon fibers through a stabilization step and a carbonization step after melt spinning. When the carbon fiber is manufactured from the isotropic pitch prepared according to the embodiment of the present invention, it is possible to produce an isotropic pitch-based carbon fiber having a high tensile strength of at least 1.5 GPa or more and an elongation rate of at least 1.5 GPa. The isotropic pitch-based carbon fiber as described above is maximized in physical properties, unlike conventional isotropic pitch-based carbon fiber is used as a general-purpose carbon material can be used in various ways to the carbon composite material required high strength, high elastic carbon fiber.

The isotropic pitch of the present invention is preferably used for producing carbon fibers, but is not limited thereto, and may be used for manufacturing various carbon materials.

 Hereinafter, a method for producing an isotropic pitch and an isotropic pitch prepared therefrom according to the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the examples and comparative examples described below are only examples to assist in understanding or implementing the present invention, and the present invention is not limited to the examples and comparative examples.

 The measurement method of the physical properties and the composition ratio of the raw materials measured through Examples and Comparative Examples are as follows.

 <84> Property Measurement Method

 <85> 1. Atomic Carbon / Hydrogen Ratio (H / C)

 <86> CHNS elemental analyzer.

<87> 2. Aromatization Degree (f a)

Analysis by C NMR (ASTM D5292)

 <8> 3.The composition of raw materials

 <90> Analysis with 2D-GC

<9i> 4.Viscosity (Pa-s)

 <92> Viscosity measured by TMA (Thermo Mechan i cal Analyzer)

5. Softening point ( ^° C)

 Softening point is measured by TMA (Thermo Mechani cal Analyzer)

6. Yield Yield was calculated by the weight of the final pitch obtained relative to the weight of the naphtha cracking residue oil charged.

 <7> 7. Mechanical Properties

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

 8. Molecular Composition of the Pitch

 The molecular composition of the pitch was analyzed by GOAED and the distribution of molecular weight was measured by GPC and the average molecular weight was obtained from the results.

<ιοι> 9. X-ray diffraction analysis

 X-ray diffractometer for molecular structure analysis of isotropic pitch uses Cu cathode. The K-c wavelength was 1.540598, the voltage of the X-ray generator was 40KV, and the tube current was 3 (½A).

<1.03> 10. T0F-MS Analysis

 JE0L's T0F-MS was used to analyze the molecular structure. The laser source was analyzed using Nd: YAG, laser intensity 5OT, mass range 10-3,000 and spiral measurement mode.

 <Examples 1 to 4> and <Comparative Examples 1 to 3> Preparation of an isotropic pitch using a halogenation method in the basic pitch manufacturing step

 <106> Composition and aromatization degree of Naphtha Cracker Bot tom shown in Table 1 to 3

Oi KNCBO) was prepared as a raw material.

<107> [Table 1]

 <108> [Table 2]

<10> [Table 3] . NCBO Compound Composition Content (%)

 Saturated Tasso Compound 1.8

 Compounds containing one aromatic ring 51.8

 Compounds Containing Two Aromatic Rings 43.1

 Compound containing three aromatic rings 3.3

 Compounds Containing Four or More Anti-Half Rings 0

 Total 100

Examples 1 to 4 prepared NCB0 at 190, 200, 210 and 220 ^° C., respectively.

V, Comparative Example 3 was each subjected to a pretreatment step at 250 ^° C. atmospheric distillation, after which the solid material was removed by filtration. In Comparative Example 1, the solid material was removed by filtration without performing the pretreatment step.

After the filtration step, 20 parts by weight of bromine was added to 100 parts by weight of the raw material produced in the thickening step. The bromination reaction was carried out at 11 CTC for 1 hour, and then debrominated at 320 ° C for 3 hours to prepare a basic pitch. Softening point and yield were measured after the completion of the basic pitch manufacturing process. Table 4 shows the measurement results.

 <) 12> [Table 4]

After putting the prepared basic pitch into the thin film evaporator, the basic pitch was heated for 30 minutes in a vacuum atmosphere, 340 ^° C. to produce an isotropic pitch. After the process was completed, the softening point, viscosity, and average molecular weight of the round pitch were measured and shown in Table 5 below. Table 5

The structure of the prepared isotropic pitch was analyzed by X-ray diffractometer, and the gamma band (κ -band) of aliphatic chain was found in XRD of 17 <2Θ <18, In the laminate structure of the condensed aromatic ring compound at 23 <2Θ <25, the (10) plane band was shown at 43 <2Θ <45 (FIG. 2). Table 6 below shows the results of the structural analysis.

 <Π6> [Table 6]

<1 Ι7> -L _a (A): Average diameter of the condensed aromatic ring compound layer ^'

 <118>-Lc (A): Average diameter of the laminated structure formed by the condensed aromatic ring compound layer.

119>-d _m (A): Average distance between condensed aromatic ring compounds in laminated structure

D _Y (A): average distance between aliphatic chains linked to a condensed aromatic ring compound

<121>-M: average number of condensed aromatic ring compound layers included in the laminated structure (= (L _c / d _m ) + 1)

<Ι22>

<Examples 5 to 8> and <Comparative Examples 4 to 6> Preparation of an isotropic pitch using the thermal polymerization method in the basic pitch manufacturing step

 <Ι24> The same NCB0 as said Examples 1-4 and Comparative Examples 1-3 was prepared.

Examples 5 to 8 performed the pre-treatment steps of the prepared NCB0 at 190, 200, 210, and 220 ^° C, respectively, in Comparative Example 4 at 120 ° C, and Comparative Example 5 by atmospheric distillation at 250 ^° C. The solids were removed by filtration. Comparative Example 3 removed the solid material through filtration without performing the pretreatment step.

After the filtration step, 100 parts by weight of the raw material produced in the thickening step was added to a metal container, and heated at 370 ^° C. for 0.5 hour to prepare a basic pitch. Softening point and yield were measured after the completion of the basic pitch manufacturing process. Table 7 shows the measurement results. Serve

<127> [Table 7]

After the prepared basic pitches were respectively introduced into the thin film evaporator, an isotropic pitch was prepared by heating the basic pitches in a vacuum atmosphere at 340 ^° C. for 30 minutes. After the process was completed, the softening point, viscosity and average molecular weight of the isotropic pitch were measured and described in Table 8 below.

<129> [Table 8]

 <i3o> The structure of the prepared isotropic pitch was analyzed by X-ray diffractometer, and XRD analysis showed that the gamma band (γ-band) of aliphatic chain (γ-band) at 23 <2Θ <25 at 17 <2Θ <18. In the laminated structure of the condensed aromatic ring compound, the (10) plane band appeared at (002) plane and 43 <2Θ <45 (FIG. 3). Table 9 shows the results of the structural analysis.

Table 9

-L _a (A): average diameter of the condensed aromatic ring compound layer

<133> — L _C (A): Average diameter of the laminated structure formed by the condensed aromatic ring compound layer

D _m (A): average distance between condensed aromatic ring compounds in a laminated structure ^''

D _Y (A): average distance between aliphatic chains linked to condensed aromatic ring compounds

-M: Average number of condensed aromatic ring compound layers included in the laminated structure (= (L _c / d, „) + 1)

<137>

 <138> Analysis of the manufactured duotropic pitch properties and structure

 As a result of XRD analysis of isotropic pitch, the isotropic pitch produced by the halogenation method and the thermal polymerization method in the manufacturing step of the basic pitch was 17 <2Θ <18 and the gamma band (γ) of aliphatic chain (γ) — Band), the (002) plane and the (10) plane band appeared at 43 <2Θ <45 in the laminate structure of the condensed aromatic ring compound at 23 <2Θ <25.

 Table 10 shows the measurement results of the physical properties and structures of the isotropic pitch prepared according to all the above Examples and Comparative Examples.

Table 10

In each example, the condensed aromatic ring compound in the structure of the isotropic pitch contained at least 2 to 7 aromatic rings, and in Table 10, the average interplanar distance (d _m ) of the condensed aromatic ring compound layer was 3.594-3.965 A. Average diameter (^) of aliphatic chains connected to the condensed aromatic ring compound was 4.829--5.172A, and the average diameter of the isotropic pitch cluster ( L _c ) belongs to 16-20 A. In each example, the average number of condensed aromatic ring compound layers stacked in an isotropic pitch cluster (M) can be expressed as (L _c / d + l and in 5.3 to 6.5 genus did. In addition, in each example, the average number (M) of condensed aromatic ring compound layers stacked in an isotropic pitch cluster can be expressed as (L _c / d + l and belongs to 5.3 to 6.5.

 Preparation of Carbon Mixed Oil Using Isotropic Pitch

Carbon fibers were prepared using an isotropic pitch. First, an isotropic pitch was injected into a cylindrical container, and then melt spun by applying a pressure of 0.8 kgf / cm ² in a nitrogen atmosphere. At this time, the diameter of the winding machine was 150 醒, the winding speed was 700rpm.

The spun fibers were each charged in a tubular electric furnace and then fed with air at a flow rate of 150 i / min. In addition, the temperature was raised at a rate of 1 ^° C / min, stabilized by maintaining for 1 hour after reaching 290 ^° C. After the stabilization step, nitrogen was injected at a rate of 150ml / min and at the same time heated up at a rate of 5 ^° C / niin to reach 800 ^° C and maintained for 0.5 hours to prepare a carbon fiber.

 The radioactivity of the isotropic pitch and the physical properties of the prepared carbon fiber are shown in Table 1 below.

<Table 11>^'

Both Comparative Examples and Examples were melt-spun, and in Table 11, high-strength carbon fibers having a tensile strength of at least 1.5 GPa and at most 2.0 GPa without single yarns were produced in each Example. 2. It belongs to 1 ~ 2.7%, and the diameter of carbon fiber belongs to 4.30-11.40 圆. On the other hand, Comparative Example 1 has a low elastic modulus due to excessively high elongation ratio of 3.2 GPa to 3.2%, and Comparative Example 2 l. The elastic modulus was low because the elongation ratio was too high compared to the tensile strength of lGPa, and Comparative Examples 3 and 4 had a high single yarn frequency, and Comparative Examples 4, 5, and 6 each carried out a tensile strength of 0.7, 0.9, and 0.9, respectively. Compared to yes Significantly lowered tensile strength.

 This shows that the physical properties and structure of the isotropic pitch produced in each example are suitable for producing high strength isotropic pitch-based carbon fibers.

Claims

[Range of request]  [Claim 1]  X-ray diffraction analysis (XRD) shows a (002) plane band at 23 <2 Θ <25 and a carbon fiber comprising a structure satisfying the following formulas (1) to (4) in which the condensed aromatic ring compound is connected by an aliphatic chain Isotropic pitch for manufacturing. 5 <L _a <15 A 一 — (1) 10 <L _c <25 A-(2) 3.50 <d _m <4.50 A-(3)  4.00 <M <8.00 A-(4) (Wherein L _a means the average diameter of the condensed aromatic ring compound layer, L _c means the average diameter of the laminated structure formed by the condensed aromatic ring compound layer, (^ in the laminated structure. Mean distance, M means the average number of condensed aromatic ring compound layers (L _c / d ,,,) + l included in the laminated structure) [Claim 2] The method of claim 1 Isotropic pitch for the production of carbon fibers with a softening point of 260 to 270 ^° C.  [Claim 3] The method of claim 1, Isotropic pitch for producing carbon fibers having an average molecular weight of 1650 to 2850. ^'  [Claim 4] The method of claim 1, Isotropic pitch for making carbon fibers with 4.80 <d _v ^' <5.20 A. (Wherein R (1 ,. means the average distance between the aliphatic chain attached to the fused aromatic ring ^") [Claim 5]  a) a pretreatment step of thermally treating and fractionating a raw material comprising any one or a mixture thereof selected from petroleum heavy oil, high boiling residues, aromatic hydrocarbon shorts and naphtha cracking process residues;  b) a filtration step of removing solid matter from the pretreated raw material;  c) preparing a basic pitch from the filtered raw material; And  d) heating the basic pitch to produce an isotropic pitch; Method for producing an isotropic pitch for producing carbon fiber comprising a ᅳ [Claim 6] The method of claim 5, The pretreatment step is to proceed by heat treatment and fractionation of the raw material to 130 to 240 ^° C. Method for producing isotropic pitch for carbon fiber production.  [Claim 7]  The method according to claim 5, wherein the step c) is basic by a halogenation method prepared by further adding a halogen compound and a radical initiator to the raw material or by heating and stirring and heating in an inert gas atmosphere to fractionate nitrogen and gaseous by-products. The manufacturing method of the isotropic pitch for carbon fiber manufacture which manufactures a pitch.  [Claim 8]  The method of claim 7, The halogenation method is a method of producing an isotropic pitch for carbon fiber manufacturing is to proceed a halogenated reaction at 0.1 to 2 hours at 100 to 120 ^° C, 2 to 4 hours at 300 to 330 ^° C.  [Claim 9]  The method of claim 7, wherein  The halogen compound is any one or a combination thereof selected from chlorine, thionyl chloride, sulfyl chloride, bromide and iodine or a method for producing an isotropic pitch for producing carbon fibers.  [Claim 10]  The method of claim 7, wherein  The radical initiator is a benzoyl peroxide, dibutyl hydroperoxide, acetyl peroxide, azobisisobutyronitrile and azobismethyl isobutylate any one or a combination thereof is a method for producing isotropic pitch for producing carbon fiber . [Claim 111] The method of claim 7, wherein  The thermal polymerization method is 0 to 350 to 38CTC. The manufacturing method of the round pitch for carbon fiber manufacturing which is advanced for 1 to 2 hours.  [Claim 12] The method of claim 7, The softening point of the basic pitch prepared by the halogenation method is 70 to 130 ^° C, the softening point of the basic pitch prepared by the thermal polymerization method is 85 to 140 ^° C. [Claim 13] The method of claim 5, The d) step is a vacuum atmosphere, the method of producing an isotropic pitch for producing carbon fiber is to proceed by heating for 0.1 to 1 hour at 300 to 350 ^° C.