WO2015076535A1 - Method for preparing carbon long fiber using isotropic oil pitch and carbon long fiber prepared by same - Google Patents

Abstract

The present invention relates to a carbon long fiber and a method for preparing the same, and a high-strength, high-elastic carbon long fiber having maximized mechanical properties can be prepared. Such a feature can be used for a carbon composite material requiring high strength and high elasticity, and thus the carbon long fiber is expected to be a substitute for existing PAN-based and anisotropic pitch based carbon fibers.

Description

 【Specification】

 [Name of invention]

 Method for producing carbon long fiber using isotropic petroleum pitch and carbon long fiber prepared therefrom

 Technical Field

 The present invention relates to a method for producing carbon long fibers using isotropic petroleum pitch and to carbon long fibers prepared therefrom. More specifically, the present invention is to prepare a fiber from a basic pitch and an isotropic pitch having a softening point of a specific range, and a method for producing a carbon filament using isotropic petroleum pitch having superior physical properties compared to conventional isotropic carbon fiber and produced therefrom It relates to long carbon fiber.

 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, improving the engine efficiency and reducing the weight of the car body. It is said to be effective in order of improving energy transfer efficiency. In particular, according to the US Department of Energy (DOE), reducing the body weight by 10¾, fuel savings of approximately 7% is possible, which requires more technical development for lighter body weight.

 <?> Lightweight body can be achieved by the use of high strength steel, aluminum alloy, etc., but carbon fiber reinforced plastic (carbon fiber reinforced plastic) is highly effective. The trend is already in use in tanks. If CFRP is used as the main material of the body structure, it is possible to reduce the increase by about 50%, which also improves the absorption performance of the masonry energy. 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 weaker than compression, and delamination is likely to occur due to impact, and the compressive strength decreases rapidly after stratification. In addition, there is a disadvantage that the manufacturing cost is difficult to apply a lot.

<5> In general, carbon fibers included in CFRP may be classified into rayon-based PAN, pitch, etc., depending on the precursor. It can be divided into carbon fiber. Among them, isotropic pitch-based carbon fiber is called general-purpose carbon fiber because it has lower price than high performance grade, and it is produced by staple-type carbon island flow by melt tbl own method to enable high temperature insulation material or activated carbon for filter. It is used as a fiber. The production of carbon fibers from petroleum, coal tar, or chemical pitches has many advantages, one of which is the high carbon-to-hydrogen ratio of these raw materials. 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 9M. However, pitch-based carbon fibers with sufficient tensile strength and modulus that can be used as composites in aerospace, aerospace, etc. are manufactured from liquid crystal pitches, petroleum and coal tar. Alternatively, in order to prepare a liquid crystal pitch from a chemical pitch, a complicated process such as pretreatment and separation of hydrogenated quinoline insolubles is required, and thus, there is a disadvantage in 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 producing a precursor for carbon fiber having a high softening point, but partially insoluble solids or mesophases are formed at a pitch heating temperature of 360 ^° C. or higher, and thus the produced carbon There is a disadvantage of poor physical properties of the fiber.

In addition, Japanese Patent Application Laid-Open No. 1996-144131 claims an isotropic mass 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 carbon fibers prepared from the pitch. 89.3 kg / 丽² (approximately 0.893 GPa) shows low physical properties to be used for CFRP for the purpose of steel sheet.

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. 10-2013-0059174 (June 05, 2013) ''

<u> "(Patent Document 2) Japanese Patent Laid-Open Publication 1996-144131 (June 04, 1996)"

 [Detailed Description of the Invention]

 [Technical problem]

 As a result of repeated studies to solve the above problems, the inventors have dealt with asphaltenes.

Provided are a method for producing a carbon long fiber comprising a specific crystal structure in which a carbon layer of (Asphal tene) form is loaded and a carbon long fiber prepared therefrom.

 Technical Solution

 The present invention provides a carbon filament comprising a specific crystal structure using an isotropic petroleum pitch, a chemical pitch, and a coal pitch and a manufacturing method thereof.

<14> 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 the condensed aromatic ring compound layers in the laminated structure (dj, the average diameter of the condensed aromatic ring compound layers, the average distance between aliphatic chains (d _Y ) and (L _c / d + l) Provided is a carbon long fiber comprising a structure represented by the average number (M) of condensed aromatic ring compound layers included in the laminated structure that can be represented. Preparing an isotropic pitch from a raw material comprising any one selected from tar fractions, aromatic hydrocarbon monomaterials, and naphtha cracking process residues, or a mixture thereof; preparing a pitch fiber melt-spun the isotropic pitch; It provides a method for producing carbon long fiber using an isotropic petroleum pitch comprising the step of carbonizing.

 Advantageous Effects

 The present invention provides a method for producing carbon fiber having excellent mechanical properties while minimizing energy consumption by inhibiting formation of insoluble solids and mesophase in pitch and minimizing energy consumption by low temperature carbonization process. Carbon filament is a high strength and high elastic carbon filament that can be applied to carbon fiber reinforced plastic (CFRP), and is expected to replace existing PAN and anisotropic pitch carbon fiber. do.

[Brief Description of Drawings] ^'

 1 is a flowchart illustrating a carbon long fiber manufacturing process of the present invention.

 Figure 2 shows the molecular weight distribution of the naphtha decomposition residue in the manufacturing method measured by T0F-MS and shows that the width of the peak is very narrow, the molecular weight is uniform.

3 is a SEM photograph of the surface of the carbon long fiber prepared according to an embodiment of the present invention.

 4 shows the results of X-ray diffraction analysis of carbon fibers. (a) is the analysis result of the carbon fiber prepared by the halogenation method of the basic pitch, (b) is the analysis result of the carbon fiber prepared by the thermal polymerization method, (c) is the PAN-based carbon fiber analysis result, (d) is an anisotropic pitch-based carbon fiber analysis result.

<2 i> Figure 5 is an analysis of the crystal structure of the carbon fiber through X-ray diffraction analysis. L _a is the average diameter of the condensed aromatic ring compound layer, 1 ^ is the average diameter of the laminated structure formed by the condensed aromatic ring compound layer, ^ is the condensed aromatic ring compound interlayer distance in the laminated structure, ^ is the condensed aromatic ring Average distance between aliphatic chains connected to the compound, M is the average number of the condensed aromatic ring compound layer included in the laminated structure. [Form for implementation of invention]

 Hereinafter, a method for preparing carbon long fibers using isotropic petroleum pitch according to the present invention and carbon long fibers prepared therefrom will be described in detail. The drawings introduced below are provided by way of example 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 denote like elements throughout the specification.

 In this case, unless there is another definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art to which the 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 a carbon long fiber and a method for producing the same, and to a carbon long fiber including a structure in which a condensed aromatic ring compound layer forms a laminated structure, and a condensed aromatic ring compound is connected by an aliphatic chain. to provide.

 The condensed aromatic ring compound layer may be a layer composed of a compound in which aromatic rings are condensed, or a compound layer containing a condensed aromatic compound, which may be connected by an aliphatic chain. Such a structure can form a carbon layer in the form of asphaltene (Asphal tene), a polymer having a chemical structure in which they are connected by an outer aliphatic chain around a condensed ring or a condensed aromatic ring including a plurality of aromatic rings.

 <26> The carbon filament of the present invention is maximized in mechanical properties of high strength and high elasticity, and can be applied to carbon fiber reinforced plastics (CFRP). Can be used in place of.

 First, the carbon long fiber of the present invention will be described in detail.

 <28> The carbon filament of the present invention is 16 <2 Θ in X-ray diffraction (X-ray diffraction)

The gamma band (γ-band) of the al iphat ic chain appears at <19, the band (002) at 19 <2 Θ <26, and the bend at (10) at 43 <2 Θ <48. The resulting condensed aromatic ring compound is an isotropic pitch containing a structure 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 _a ), the average distance between condensed aromatic ring compound layers (d, „) and (L _c / d _m ) + l in the laminated structure. Included axis It can be described as the average number of polyaromatic ring compound layers (M), where the condensed aromatic ring compounds are linked by aliphatic chains and the average distance between aliphatic chains connected to the condensed aromatic ring compounds is also added to explain the structure. Can be. In addition, the laminated structure formed by the condensed aromatic ring compound layer may be expressed as a nano cluster. Each measurement result of the crystal structure can be represented by the XRD measurement results, Bragg equation and Scherrer equation.

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

(L _c ) is 30 to 60, preferably 30 to 50, and the average diameter () of the condensed aromatic ring compound pack is 10 to 50, preferably 15 to 40, and the average of the condensed aromatic ring compound interlayers in the laminated structure. Distance (d is 3.50 to 4.20, preferably 3.70 to

4.00, the average distance ((^) between aliphatic chains linked to the condensed aromatic compound (4) is 4.00 to 6.00, preferably 4.50 to 5.50, the average number (M) of the condensed aromatic ring compound layer included in the laminated structure is 9.0 to 18.0, preferably 9.5 to 14.5.

<3 1> The carbon filament produced in the present invention has high strength and high elastic properties only when the crystal structure satisfies the above range. If it is out of the above range, the tensile strength is significantly reduced, the elongation is low or too high, the elastic modulus is not good.

 The long carbon fiber of the present invention may be represented as follows according to the crystal structure analysis result.

 <33> The long carbon fiber of the present invention was measured at a diffraction angle of 19 <2 Θ <26 by X-ray diffraction (XRD).

A (002) cotton band appears, and is a carbon long fiber containing a crystal structure satisfying the following formulas (1) to (4) in which a condensed aromatic ring compound is connected by an aliphatic chain.

<34> 30 <L _a <60 Α-(1)

<35> 10 <L _c <50 A-ᅳ (2)

<36> 3.50 <d _m <4.20 A-(3)

 <37> 9.0 <M <18.0-(4)

According to one embodiment of the present invention, even if the above formulas (1), (2) and (3) are satisfied, the tensile strength of the carbon fiber is significantly reduced or the elongation is lowered. . According to another embodiment of the present invention, even when the above formulas (2) and (3) are satisfied, the tensile strength is remarkably reduced or the elongation is too high so as not to satisfy the formulas (1) and (4). According to another embodiment of the present invention, the formula (1) and (2) If it is satisfactory, the tensile strength and the elongation rate are remarkably reduced if the contents (3) and (4) are not satisfied.

The carbon long fiber may be represented in more detail by further expressing the average distance (d _Y ) between aliphatic chains connected to the condensed aromatic ring compound in the structure included in the carbon long fiber.

 <40> Carbon long fibers having better physical properties can be prepared in which the average distance (^) between aliphatic chains linked to the formulas (1) to (4) and the condensed aromatic ring compound of the present invention is further specified in a preferred range. Can be.

The carbon long fiber of the present invention is a high strength, high elastic carbon long fiber having a diameter of 1 to 20 GPa, a tensile strength of at least 1.5 GPa or more, and an elongation rate of 2% or more.

Next, the carbon long fiber manufacturing method of the present invention will be described in detail. ^'

First, a method for producing carbon long fibers using isotropic petroleum pitch according to an embodiment of the present invention,

 A) preparing an isotropic pitch from a raw material comprising any one or a mixture of idols selected from petroleum heavy oil, high boiling residue and naphtha cracking process residue;

B) a pitch fiber manufacturing step of melt spinning the isotropic pitch; ^'

 C) heat treating and stabilizing the spun pitch fibers; And

 D) carbonizing the pitch fibers;

 It may include <48>.

 The raw materials may include petroleum heavy oil, high boiling residue oil, coal tar fraction, aromatic hydrocarbon short materials such as naphthalene, methylnaphthalene or anthracene, or naphtha cracking process residue oil. In addition, pyrolysis heavy residues having a wide molecular weight distribution can be used.

 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 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.

The pyrolysis fuel oil is produced at the bottom of the naphtha cracking process and may include various aromatic hydrocarbons. Specific examples of the aromatic hydrocarbons include ethyl benzene, 1-ethenyl ᅳ 3-methylbenzene, indene, and 1-ethyl-3 methylbenzene. -ethy卜3-methyl benzene), 1- methyl-ethyl benzene (1- methyl ethyl benzene), 2- ethyl-1, 3-dimethylbenzene ^{(2-ethyl-], 3-} dimethyl benzene), loop Propylbenzene, 1-methyl-4- (2—propenyl) -benzene (l-lathy4- (2-propenyl) benzene), l, la, 6, 6a-tetrahydrocyclocyclofinene (1, la, 6, 6a-tetrahydro-cycloprop [a] indene), 2-ethyl-1H-indene, 1-methyl-1H-indene ), 4,7-dimethyl-lH-indene (4, dimethy 卜 IH-indene), l-methyl-9H-Fluorene, 1,7-dimethyl naphthalene (1,7-dimethyl naphthalene), 2-methylindene, 4,4'-dimethyl biphenyl, naphthalene, 4-methyl-1,1'-biphenyl (4 -methyl-l, l'-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 content, which 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. It may include.

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

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

 The high boiling point oil is preferably contained in an amount of 5 to 15% by weight based on 100% by weight of the entire raw material. When the content is less than 5% by weight, the effect may be insignificant. The effect may not be significant for the amount.

 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. If the aromaticity is higher than 0.9, there is no particular limitation, but if the aromaticity is 0.9 or more, the effect of a 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.

 Proof of manufacturing method of carbon long fiber using isotropic petroleum pitch of the present invention

 Al) a pretreatment step of heat treating and fractionating the raw material;

A2) a filtration step of removing solid matter from the pretreated raw material; A3) preparing a basic pitch from the filtered raw material; And

 A4) heating the basic pitch to produce an isotropic pitch;

 It can include <63>.

 In step a), the pretreatment may include heating and fractionation, and is a step of removing low molecular weight substances which are unlikely to form oligomers by polymerization reaction, and at the same time, the reactivity included in the raw material is accompanied by reaction. The aim is to convert strong, unstable compounds into compounds that are more stable and effective for the production of isotropic pitches.

The pretreatment step may be carried out by atmospheric distillation until no volatilization occurs at a temperature of 130 to 240 ^° C., preferably 150 to 23 CTC, more preferably 190 to 22 CTC. In the pretreatment step, the heating temperature may affect the physical properties of the carbon fiber and the properties of the bay direct pitch and isotropic pitch such as the composition ratio of the raw material and the degree of aromatization. In addition, the pretreatment step may proceed at atmospheric pressure, but may proceed under reduced pressure. At this time, the pretreatment process can be carried out at a lower temperature through the reduced pressure, and the pressure and the temperature can be freely adjusted within the range to obtain the same effect as the normal pressure.

 A2) The filtration step is a process of removing solid matters, which are solid residues containing impurities such as metals, sulfur, and nitrogen, which act as a cracker on the structure of the carbon fiber to reduce strength. Can cause

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

 The filtration step may be carried out after the polymerization of the basic pitch, an isotropic pitch intermediate, and in some cases, after the pretreatment step and after the basic pitch polymerization step. That is, in the manufacturing method, step (al) may be performed after step, and in some cases, step (al) and step (a3) may be performed after step, respectively.

A3) The basic pitch manufacturing step is a step of preparing a basic pitch having a high softening point without generating mesophases by reacting the raw material after the filtration step with heating, and may be performed by a halogenation method or a thermal polymerization method.

 The halogenation method may be performed by further adding a halogen compound and a radical initiator, followed by heating. Preferably, the halogen compound is added and then mixed with the radical initiator.

<7i> Halogenated compounds are chlorine (CI ₂ ), thionyl chloride (S0C1 ₂ ), sulfuryl chloride

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

<72> radical initiator is benzoyl peroxide (Benzoyl peroxide), di-butyl hydroperoxide oksayi de _{(di-t-butyl. Hydroperoxide} ), acetyl peroxide

<73> (Acetyl peroxide) an organic peroxide (Organic Peroxide) and azobisisobutyronitrile Ronnie casting reel, such as ^{(AIBN; ■ a, x '} Azobi si sobutyroni tr i 1 e), azobis methyl isobutyrate (α, α Azo compounds such as' -Azobi smethyl i sobutyrate), or those selected from the group consisting of two or more thereof may 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.

In the halogenation method, a halogenation reaction is performed at 100 to 120 ^° C. for 0.5 to 2 hours to replace hydrogen in an aromatic alkyl group with halogen, and then polymerization is performed by dehalogenation reaction at 300 to 33 CTC for 2 to 4 hours. Can be. In addition, the dehalogenation reaction is a subsequent process, it is possible to further increase the purity of the basic pitch produced by decomposing the halogen compound and radical initiator which may remain in the basic pitch after reaction. In a particularly LAL halogenated banung good to banung temperature not exceeding 330 ^° C, 330 ^° C in excess of it is as a result proceeds upset anisotropic screen or coking of the basic pitch of the excess polymerization only occurs actively decomposition of the halogenated compound and radical initiator The mechanical properties of the carbon fiber are greatly reduced. 、

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

The thermal polymerization method may be performed at 0.01 to 2 hours at 350 to 380 ^° C. Distillation 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 38 CTC. If the reaction temperature exceeds 380 ^° C, the reaction temperature may exceed the range of uniform anisotropy pitch for the present invention. Mesophase may be produced or coking may occur to produce non-uniform 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 smoothing the flow of the fluid continuously flowing in step (c) to step (d) of the manufacturing method, the basic pitch thickening condensation aromatics prepared from step (c) To the absolute amount of oligomer 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, and the softening point of the basic pitch affects the physical properties, molecular structure and laminated structure of the final isotropic pitch produced according to the convenience of the process configuration. It can be adjusted freely within the range not given.

 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 generation 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.

<8 i> 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 35 CTC, a meso phase is 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.

According to an embodiment of the present invention, the isotropic pitch has a softening point of 255 to 275 ^° C. Preferably it may be 260 to 270 ^° C. In addition, the isotropic pitch flat molecular weight (Mw) of the present invention may be 1500 to 3000, preferably 1700 to 2850. The average molecular weight, softening point, and softening point of the isotropic pitch can greatly affect the physical properties of the carbon fiber produced.

Pitch fiber manufacturing step can be prepared by melt spinning, wherein the nitrogen atmosphere, temperature 300 to 320 ^° C, pressure 0.01 to 10 kgf / cm ² , winding speed 500 to 1, 500 rpm can be carried out under the conditions. have.

The pitch fiber manufacturing step may be more preferably 0.1 to 2 kgf / cm ² . However, in the case of the radiation pressure, the spinneret and the number of spinneret packs, the diameter of the spinneret, the length of the spinneret may vary depending on the viscosity and temperature of the spinneret,

The force is not limited thereto, and may be, for example, 100 kgf / cm ² or more on a commercial scale. .

The stabilization step is a step in which oxidative stabilization and thermal stabilization of spun isotropic pitch fibers are performed to control shrinkage and expansion to polymerize a ladder structure. Also long carbon fiber may be stable. The stabilization step may be performed for 1 to 5 hours in the case of a batch ^at 180 to 300 ^° C, wherein the temperature increase rate may be 1 to 5 ^° C / min. In continuous mode, the residence time can be from 1 to 10 hours. In addition, the gas atmosphere used as the oxidizing agent is not particularly limited and may be performed in a normal air atmosphere, and the supply rate is not limited, but when using oxygen diluted with a gas used as the oxidizing agent, the concentration of oxygen is determined by the oxidizing gas. It may be between 1-20% of the total volume.

 The carbonization step is to induce intermolecular reactions by high temperature heat treatment to advance crosslinking between the polymers of the ladder structure, and to produce a more aligned carbon structure to produce carbon fibers having high strength.

The carbonization step may be performed by maintaining the inert gas atmosphere at 700 to 1 and 500 ^° C. for 0.05 to 2 hours. In the case of a batch temperature increase rate may be 1 to 5 C / ra. If continuous, the residence time may be 0.05 to 2 hours. However, the injection amount of the inert gas during the carbonization process is not limited, and can be freely controlled within the range of not impairing the physical properties of the carbon long fiber.

In the case of conventional carbon fibers, the process proceeds at a temperature of 1,700 ^° C. or more, and the fibers are manufactured through several carbonization processes. In contrast, the carbonization step of the present invention can proceed at a lower temperature than the carbonization step for the conventional carbon fiber manufacturing, has the advantage of short carbonization progress, it is possible to reduce the manufacturing cost. The stabilization and carbonization step can be carried out using a conventional apparatus, for example, after the pitch fibers are charged into a tubular electric furnace, air or inert gas can be injected, and heated. ^'

 Long carbon fiber may vary depending on the spinning conditions, but the fiber diameter of 1 to 20

IM, tensile strength can be 1.5 GPa or more, elongation 2% or more. In particular, the carbon filament according to the present invention may have a tensile strength of 1.5 GPa or more, more specifically, 1.5 to 3.5 GPa. When the tensile strength is less than 1.5 GPa, it does not meet the physical properties required in the field of carbon fiber reinforced plastics, which is the main purpose of the present invention, and when it is more than 3.5 GPa, it may take a lot of time during the process to reduce the production speed. This can lead to increased production costs. However, the tensile strength, fiber diameter, and elongation rate of the carbon long fiber may have physical properties greater than or equal to the above range depending on the type of raw material, composition ratio, heat treatment temperature, basic pitch manufacturing method, pitch softening point, and the like. It may be.

According to the manufacturing method of the present invention, it is possible to provide a carbon filament having a tensile strength of at least 1.5 GPa and an elongation of at least 2% while maintaining a structure of an isotropic pitch including an asphaltene type structure. Such a structure can be carbonized at a low temperature of 700 to 1500 ^° C. or lower during the carbonization step, and more specifically to a low carbonization temperature of 800 ^° C. to 1200 ^° C. or lower. Due to this, the energy consumption during the carbonization process can be minimized.

 <92> It can be applied to carbon fiber reinforced plastic (CFRP) that requires high strength by showing the value over 1.5GPa of tensile strength, and its excellent properties include the existing PAN (polyacrylomtrile) carbon fiber. It seems to be able to replace CF P.

 Through the following examples and comparative examples will be described in more detail with respect to the method for producing carbon long fiber using the isotropic petroleum pitch according to the present invention and the carbon long fiber produced therefrom. However, the following Examples and Comparative Examples 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 measuring method of the physical properties measured by the Example and the comparative example is as follows.

 <95> Property Measurement Method

 <96> 1. Carbon to hydrogen atomic ratio (H / C)

 <97> CHNS elemental analysis

 2. Aromatization degree (fa)

Assay by ¹³ C NMR (ASTM D5292)

 <ιοο> 3. Composition of raw materials

<ioi> Analyzing with 2D-GC

 4. Viscosity (Pas)

 <103> Viscosity measured by TMA (Thermo Mechanical Analyzer)

5. Softening point ( ^° C)

 Softening point measured by TMA (Thermo Mechanical Analyzer)

 <io »> 6. Yield

 Yield was calculated by the increase in the final pitch obtained relative to the increase in naphtha cracking residue added.

 7. Mechanical Properties

 <| 09> Stress-Strain curves were measured with a universal test machine (UTM) equipped with a 2N load cell on a sample of carbon fiber to calculate tensile strength (GPa) and elongation (%). The results were calculated from the diameters of the fibers analyzed by electron microscopy.

 <uo> 8. Molecular Composition of the Pitch

Molecular composition of <πι> pitch was analyzed by GC-AED and distribution of molecular weight was measured by GPC and the average molecular weight was obtained from the result. <ιΐ2> 9. X-ray diffraction analysis

 The X-ray diffractometer for the molecular structure analysis of the isotropic pitch using Cu cathode, the K-c wavelength was 1.540598, the voltage of the X-ray generator was 40KV, the tube current was 30mA.

<ι ΐ4> 10. T0F-MS analysis

 <ιΐ5> JE0L's T0F-MS was used to analyze the molecular structure. Laser source

Nd: YAG, laser intensity was 50%, mass range was 10 to 3,000, using a spiral measurement mode.

 <116>

 <ιΐ7> <Examples 1 to 4> and <Comparative Examples 1 to 3> Preparation of long carbon fiber by halogenation method in basic pitch manufacturing step

 <U8> Naphtha Cracker Bottom as shown in Tables 1 to 3

Oil (NCBO) was prepared as a raw material.

119> [Table 1] ^'

 <120> [Table 2]

 <121> [Table 3]

 Examples 1 to 4 are comparative examples of prepared prepared NCB0 at 190, 200, 210, and 22 CTC, respectively.

 2 was carried out a pretreatment step of 12CTC, Comparative Example 3 at 25CTC, atmospheric distillation, and then 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 intermediate step. After bromination at 110 ° C for 1 hour, again 320 ^A debris cracking reaction was conducted at 3 ^° 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.

<124> 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 isotropic pitch were measured and described in Table 5 below. TABLE 5

 After each of the isotropic pitches were injected into the cylindrical vessels, they were spun by applying a pressure of O. Skgf / on in a nitrogen atmosphere. At this time, the diameter of the winding machine was 150 匪, the winding speed was 700rpm.

Spinned pitch fibers were charged in tubular electric furnaces, and air was supplied at a flow rate of 150 miVmin. In addition, the temperature was raised at a rate of 1 ^° C./min, and maintained for 1 hour after reaching 29 CTC.

 The pitch fiber after the stabilization stage is injected with nitrogen at a rate of 15 (l / min and 5

^After increasing the temperature at ^° C / min to reach 800 ^° C was maintained for 0.5 hours to prepare a carbon long fiber.

The structure of the prepared carbon filament was analyzed by X-ray diffractometer, and the XRD analysis showed that the gamma band (γ-band), 19 <2Θ <of aliphatic chain at 16 <2Θ <19. In the layer structure of the condensed aromatic ring compound at 26, the (002) plane, at 43 <2Θ <48 (10) cotton band appeared (FIG. 4). X-ray diffraction analysis showed that in each of the Examples and Comparative Examples several condensed aromatic ring compound layers were superimposed at different diffraction angles. As a result of analyzing the long carbon fiber structure from XRD, asphalt-like condensed aromatic ring compounds containing 4 to 13 aromatic rings were connected by aliphatic hex. Table 6 shows the average value of each value shown in FIG.

 Tensile strength, diameter, and elongation of the prepared carbon filaments were measured.

 Table 6 below shows the results of physical and structural analysis of the prepared carbon fiber.

 <133> [Table 6]

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

 Lc (A): average diameter of the laminated structure formed by the condensed aromatic ring compound layer

<13: 6>-d _m (A): average distance between condensed aromatic ring compound layers in a laminated structure

D _v (A): Average distance between aliphatic chains linked to condensed aromatic ring compounds.

<| 38> -M: Average number of condensed aromatic ring compound layers included in the laminated structure (= (L _c / d + 1) 139>

<Examples ₅ to 8> and <Comparative Examples 4 to 6> Preparation of long carbon fibers by thermal polymerization in the basic pitch manufacturing step

 The same NCB0 as in Example 1-4 and Comparative Examples 1 to 3 was prepared.

<| 42> Example ^. 5-8 prepared prepared NCB0 comparative example at 190 200 and 210 220 ^° C, respectively 5 at 120 ^° C., Comparative Example 6 at 250 ^° C., respectively, pretreatment steps were carried out by atmospheric distillation and then through filtration. Solid matter was removed. Comparative Example 4 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 intermediate step was put in 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.

 <Table 7> [Table 7]

After preparing 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 isotropic pitch were measured and shown in Table 8 below. Table 8

 After the isotropic pitches were respectively injected into the cylindrical vessels, they were spun at 0.8 kgf / cm under a nitrogen atmosphere. At this time, the diameter of the winding machine was 150 讓 and the winding speed was 700rpm.

In the stabilization step, the spinned pitch fibers were charged in tubular electric furnaces, respectively, and air was supplied at a flow rate of 150 in.e / min. It was also heated at a rate of 1 ^° C / min, and maintained for 1 hour after reaching 290 ^° C.

 <149> The pitch fiber after the stabilization stage is injected at a rate of 150 ml / min and 5

^After heating up at the rate of ^° C / mi and reaching 800 ^° C, it is maintained for 0.5 hours Prepared.

 <150> The structure of the prepared carbon fiber was analyzed using an X-ray diffractometer, and the XRD analysis showed that the gamma band (γ-band) of the aliphatic chain (γ-band) and 19 <2Θ <were 16 <2Θ <19. In the layered structure of the condensed aromatic ring compound at 26, (10) plane bands were observed at (002) plane and 43 <2Θ <48 (FIG. 4). As a result of X-ray erosion analysis, several condensed aromatic ring compound layers were observed at different diffraction angles in each of Examples and Comparative Examples. As a result of analyzing the carbon fiber structure from XRD, as shown in FIG. A condensed aromatic ring compound containing an aromatic ring is characterized by an asphaltene-like structure in which a layer formed by connecting an aliphatic chain is laminated. Table 9 shows the average value of each value shown in FIG.

 Tensile strength, diameter, and elongation of the prepared carbon filaments were measured.

 Table 9 shows the results of the physical and structural analysis of the prepared carbon fiber.

 <153> [Table 9]

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

 Lc (A): average diameter of the laminated structure formed by the condensed aromatic ring compound layer

<I56>-d _m (A): Average distance between condensed aromatic ring compound layers in a laminated structure

 D (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)

<159> <160> Analysis of Physical Properties and Structure of Small Intestine Fibers after Manufacturing

 As a result of XRD analysis of the structure of the prepared carbon long fibers, the carbon long fibers manufactured by the halogenation method and the thermal polymerization method in the manufacturing stage of the basic pitch were all aliphatic chains at 16 <2Θ <19. The (002) plane and (10) plane band at 43 <2Θ <48 appeared in the lamination structure of the condensed aromatic ring compound at gamma band (γ-band) of 19 <2Θ <26.

 Table 10 shows measurement results of physical properties and structures of the carbon long fibers prepared according to all the examples and comparative examples.

 <163> [Table 10]

<164> 각 실시예에서 탄소장섬유 구조의 축합방향족 고리 화합물은 최소 4 내지 최 대 13개의 방향족 고리를 포함하였고, 표 10을 보면 축합방향족 고리 화합물 층의 평균 면간 거리 (d_m)가 3.72~3.95A에 속했고， 축합방향족 고리 화합물 층의 평균 직 경 (L 은 17-39A에 속했고, 축합방향족 고리 화합물에 연결된 지방족사슬 간 평균 거리 (d_Y)는 4.87-5.43A에 속했고， 축합방향족 고리 화합물 층어 형성하는 적층 구 조의 평균 직경 (L 은 33 49A에 속했다. 또한， 각 실시예에서 등방성 피치 클러스 터에서 적층된 축합방향족 고리 화합물 층의 평균 개수 (M)는 (L_c/d_m)+l로 나타낼 수 있고 9.6~13.8에 속했다.

In each example, the condensed aromatic ring compound of the long carbon fiber structure contained at least 4 to 13 aromatic rings. Referring to Table 10, the average interplanar distance (d _m ) of the condensed aromatic ring compound layer was 3.72∼. Belonged to 3.95A, the average diameter of the condensed aromatic ring compound layer (L belonged to 17-39A, the average distance between aliphatic chains linked to the condensed aromatic ring compound (d _Y ) belonged to 4.87-5.43A, and the condensed aromatic ring compound The average diameter of the laminated structure formed by layering (L belongs to 33 49 A. Also, in each example, the average number of condensed aromatic ring compound layers laminated in an isotropic pitch cluster (M) is (L _c / d _m ) + It can be represented by l and belongs to 9.6 ~ 13.8.

 This structure of the long carbon fiber has excellent physical properties, and the structure

It is a structure clearly distinguished from PAN-based carbon fibers and anisotropic pitch-based carbon fibers.

 In Table 10, in each embodiment, a high-strength carbon fiber having a tensile strength of at least 1.5 GPa and a maximum of 2.0 GPa was produced, an elongation of 2.1-2.7%, and the diameter of the carbon fiber was 4.30 ~. It belongs to 11..40. On the other hand, Comparative Examples 1 and 2 had an elongation ratio of 3.2% and 3.1%, respectively, so that the elastic modulus was not good. Comparative Example 3 had an elongation of 1.9% and a tensile strength of 1.0. Examples 4 and 5-the tensile strength was significantly dropped to 0.7, 0.9, Comparative Example 6 was significantly reduced physical properties of the carbon fiber with a tensile strength of 1.5% elongation, 0.9 tensile strength.

 <167>

 <Example 9>

 <16> The pretreatment step was carried out at 220 ° C, and the carbon fiber was prepared in the same manner as in Examples 1 to 4 and Comparative Examples 1 to 3 except that the temperature was maintained at 1200 ° C after the stabilization step. Table 11 shows the carbon fiber and the physical properties of Example 4.

<170> [Table 11]

 In Table 11, when the carbonization temperature was increased to 120 CTC, the tensile strength was increased while maintaining the diameter and elongation.

 <172>

 <173> <Example 10>

The pretreatment step is performed at 220 ° C., and the temperature is raised to 1200 ° C. after the stabilization step. Carbon fibers were produced in the same manner as in Examples 5 to 8 and Comparative Examples 4 to 6, except that the mixture was retained by the same. Table 12 shows the carbon fiber and the physical properties of Example 8. Table 12

 In Table 12, when the carbonization temperature increased to 120CTC, the tensile strength increased while maintaining the diameter and elongation.

Claims

【Scope of Claim】 【Claim 1】 a) manufacturing isotropic pitch from a raw material containing any one or a mixture thereof selected from heavy petroleum oil, high boiling point residue oil, aromatic hydrocarbon single material, and naphtha cracking process residue; b) a pitch fiber manufacturing step of melt spinning the isotropic pitch; c) stabilizing the spun pitch fiber by heat treatment; and d) carbonizing the pitch fibers; Method for manufacturing carbon long fibers using isotropic petroleum pitch comprising. 【Claim 2】 ^. In clause 1, A method of producing carbon long fiber using isotropic petroleum pitch, wherein the tensile strength of the carbon long fiber is 1.5 GPa or more. 【Claim 3】 It includes manufacturing carbon long fibers using isotropic pitch manufactured from raw materials containing any one or a mixture thereof selected from petroleum distillate, high boiling point residue, aromatic hydrocarbon singles, and naphtha cracking process residue. ，The carbon long fiber is a method of manufacturing carbon long fiber using isotropic petroleum pitch with a tensile strength of 1.5 GPa or more. 【Claim 4】 In clause 3, The manufacturing method of carbon long fiber using the isotropic petroleum pitch is a) manufacturing isotropic pitch from a raw material containing any one or a mixture thereof selected from petroleum distillate, high boiling point residue, aromatic hydrocarbon single substance, and naphtha cracking process residue; b) a pitch fiber manufacturing step of melt spinning the isotropic pitch; c) stabilizing the spun pitch fiber by heat treatment; and d) carbonizing the pitch fibers; Method for manufacturing carbon long fiber using isotropic petroleum pitch containing. 【Claim 5】 According to claim 1 or 3, The carbon long fiber is a method of producing carbon long fiber with a fiber diameter of 1 to 20卿 and an elongation of 2% or more. [Claim 6] According to paragraph 1 or 4, Step a) above is al) a pretreatment step of heat treating and fractionating the raw materials; a2) Filtration step to remove solid substances from pretreated raw materials; a3) manufacturing basic pitch from filtered raw materials; and a4) manufacturing isotropic pitch by heating the basic pitch; Method for manufacturing carbon long fibers using isotropic petroleum pitch comprising. 【Claim 7】 According to clause 6, The pretreatment step is a method of producing carbon long fibers using isotropic petroleum pitch, which is carried out by heat treating and fractionating the raw materials at 130 to 240 ^° C. 【Claim 8】 According to clause 6, The step a3) is an isotropic method of producing basic pitch by a halogenation method by adding a halogen compound and a radical initiator to the raw material and then heating it, or by a thermal polymerization method of separating nitrogen and gaseous by-products by stirring and heating in an inert gas atmosphere. Method for manufacturing carbon long fiber using oil patch. 【Claim 9】. , According to clause 8, The halogenation method involves conducting a halogenation reaction at 100 to 120 ^° C for 0.5 to 2 hours, followed by a dehalogenation reaction at 300 to 330 ^° C for 2 to 4 hours, producing carbon long fibers using isotropic petroleum pitch. method . [Claim 10] According to clause 8, The halogen compound is any one selected from chlorine, thionyl chloride, sulfuryl chloride, bromine, and iodine, or a mixture thereof. A method of producing carbon long fibers using isotropic petroleum pitch. 【Claim 11】 In clause 8, The radical initiator is a carbon long fiber using isotropic petroleum pitch, which is any one selected from benzoyl peroxide, dibutyl hydroperoxide, acetyl peroxide, azobisisobutyronitrile, and azobismethyl isobutyrate, or a mixture thereof. manufacturing room 【Claim 12】 In clause 8, The thermal polymerization method is a method of producing carbon long fibers using isotropic petroleum pitch, which is carried out at 350 to 380 ^° C for 0.1 to 2 hours. 【Claim 13】 In clause 8, The softening point of the basic pitch manufactured by the halogenation method is 70 to 130 ^° C, and the softening point of the basic pitch manufactured by the thermal polymerization method is 85 to 140 ^° C. Method for producing carbon long fibers using isotropic petroleum pitch. 【Claim 14】 According to clause 6, The step a4) is a method of producing carbon long fibers using isotropic petroleum pitch, which is carried out by heating in a vacuum atmosphere at 300 to 350 ^° C for 0.1 to 1 hour. 【Claim 15】 In clause 14, Method for producing carbon long fibers using isotropic petroleum pitch, where the softening point of the isotropic pitch is 260 to 270 ^° C. 【Claim 16】 According to claim 1 or 4, Step b) is a carbon long fiber using isotropic petroleum pitch, which produces pitch fibers under the conditions of nitrogen atmosphere, temperature 300 to 320 ^° C, pressure 0.01 to 10 kgf / era ² , winding speed 500 to l, 500 rpm. Manufacturing method. 【Claim 17】 According to claim 1 or 4, Step c) is a method of manufacturing carbon long fibers using isotropic petroleum pitch, which is carried out at 250 to 300 ^° C for 1 to 5 hours. 【Claim 18】 According to paragraph 1 or 4, Step d) is a method of producing carbon long fibers using isotropic petroleum pitch, which is carried out in an inert gas atmosphere at 800 to 1, 200 ^° C for 0.5 to 30 hours. 【Claim 19】 In A carbon long fiber containing a crystal structure that satisfies the following formulas (ι) to (4) in which a group ring compound is connected to an aliphatic chain. 30 < L _a < 60 A — (1) 10 < L _c < 50 A — (2) 3.50 < d _m < 4.20A -― (3) 9.0 < M < 18.0 —- (4) (In the above formula, L _a refers to the average diameter of the condensed aromatic ring compound layer, L _c refers to the average diameter of the stacked structure formed by the condensed aromatic ring compound layer, and 4„ refers to the average between the condensed aromatic ring compound layers in the stacked structure. means the distance, and M means the average number of condensed aromatic ring compound layers included in the stacked structure (L _c /d,„)+l) 【Claim 20】 According to clause 19, The carbon long fiber is a carbon long fiber with a tensile strength of 1.5 GPa or more. 【Claim 21】 In clause 20, The carbon long fiber is a carbon long fiber with an elongation of 2% or more. 【Claim 22】 In clause 19, Carbon long fiber with 4.80 < d, < 5.20A. (In the above formula, ^ refers to the average distance between aliphatic chains connected to the condensed aromatic ring compound.)