KR20130059174A - Preparation method of pitch for carbon fiber - Google Patents

Abstract

PURPOSE: A manufacturing method of an isotropic pitch for carbon fiber is provided to have a high softening point with a high yield at high temperature without using a separate catalyst. CONSTITUTION: A mixture is formed by mixing a petroleum process residue and a C9 petroleum resin. The mixture is heated up with the first. The firstly heated mixture is heated up with the second. The secondly heated mixture is heated up with the third. A heating temperature is 80-100°C and a heating time is 1~2 hours in a first heating step. A chain extension reaction is induced in the first heating step. A heating temperature is 250-300°C and a heating time is 1/2-2 hours in a second heating temperature. Low boiling point water is removed in the second heating step. A heating temperature is 320-360°C and a heating time is 3-8 hours in a third heating step.

Description

Manufacturing method of pitch for carbon fiber {PREPARATION METHOD OF PITCH FOR CARBON FIBER}

The present invention relates to a method for producing an isotropic pitch for carbon fibers having a high softening point, and more particularly, after mixing a petroleum process residue oil and a C9 petroleum resin to form a mixture, and heating the mixture to thermally polymerize the carbon fiber. It relates to a method for producing a isotropic pitch. According to the production method of the present invention, a separate catalyst is not required, and an isotropic pitch for carbon fibers having a high softening point can be produced with a high yield even at a relatively low temperature.

Carbon materials have a carbon content of 95% or more, and materials for various uses that apply various properties of carbon have been developed and produced. As a raw material for the carbon material, all carbon compounds are possible in principle, but usually a suitable raw material is selected according to the required physical properties and manufacturing cost of the final product.

Among them, especially petroleum-based raw materials, FCC (fluidized catalytic cracker), DO (decant oil) and PFO (pyrolized fuel oil) have high degree of aromatization, low sulfur and insoluble content and high strength carbon fiber or needlecock. It is attracting attention as a suitable raw material for high value added carbon materials such as coke).

Conventionally, a method for producing anisotropic pitches from heavy samples such as PFO is a method of heat treatment for about 14 hours or longer at 400 ℃ from the precursor pitch from the light oil is removed, or fractionated to an appropriate range using a solvent such as benzene or toluene It has been largely distinguished by a method of post-heat treatment.

In this regard, various methods, such as catalytic carbonization reaction or reduced pressure heat treatment process, have been attempted due to efforts to develop carbon materials for various uses.

The carbonization process of reforming heavy oil such as PFO into pitch is a pyrolysis reaction in the oil to release gas and light oil out of the system, and at the same time, the molecules activated by radical formation cyclization and aromatization ( aromatization), polycondensation (polycondensation) means a series of processes.

Here, the planar molecules of the condensed polycyclic aromatic group generated during the polycondensation reaction are stacked in parallel to form a liquid crystal having an intermediate property of a solid and a liquid, called mesophase, and the degree of stacking Depending on the orientation of the time it is divided into optically isotropic or anisotropic pitch.

The general pitch-based carbon fiber is largely divided into liquid crystal pitch-based carbon fiber and isotropic pitch-based carbon fiber according to the kind of pitch which is a precursor. The liquid crystal pitch-based carbon fiber is prepared using optically anisotropic liquid crystal pitch as a precursor, and isotropic pitch-based carbon fiber is prepared using an optically isotropic isotropic pitch as a precursor. The mechanical properties of the produced carbon fiber, if the liquid crystal pitch-based carbon fiber generally exhibits high strength and high elasticity, isotropic pitch-based carbon fiber shows the general properties of low strength and low elasticity.

In general, the pitch-based carbon fiber is produced by melt spinning a pitch, which is a precursor, using a spinning machine, and then oxidizing and stabilizing the fiberized pitch in an oxidizing atmosphere at a temperature range of 150 to 350 ° C., followed by 700 to 3000 ° C. It is prepared by treating it for a certain period of time depending on the application in an inert atmosphere in the temperature range.

The production cost of fiber in carbon fiber production is influenced by the price of precursor pitch as raw material, radioactivity of precursor pitch, rate of oxidation stabilization, carbonization yield after carbonization process, and oxidation for which long time reaction is necessary for the required time by manufacturing process. Since the stabilization process is known to require the longest time, the development of precursor pitch excellent in oxidation stabilization performance is known as an important technique.

Pitch precursors for the pitch-based carbon fiber are divided into liquid crystal pitch and isotropic pitch as described above, and vacuum distillation and solvent extraction as a method of producing an isotropic pitch having a softening point of 200 ° C. or more, which is used as a raw material of isotropic pitch-based carbon fiber. The method of removing a low molecular weight component by this method, the method of condensing a low molecular weight component in a raw material into a high molecular component by simple thermal condensation, and the method of manufacturing the said two methods simultaneously are mentioned. However, with this method, although isotropic pitches having a relatively narrow molecular weight distribution can be prepared from raw materials having a wide molecular weight distribution, they are not only low in yield, but also have a component which is easily liquid crystalline when heated. There are disadvantages in terms of pitch homogeneity and radioactivity.

Japanese Patent Laid-Open Publication No. 1994-256767 describes a method of removing a quinoline insoluble from a coal-based pitch as a raw material and then hydrogenating it, followed by fractionating an oxidizing gas to prepare a high softening point isotropic pitch, which is a precursor of isotropic carbon fibers. .

Further, Japanese Patent Laid-Open Publication No. 1993-132767 and Japanese Patent Laid-Open Publication No. 1993-132675 describe a method of adding dinitronaphthalene or the like when heat-treating for producing a pitch in order to increase the softening point of an isotropic pitch precursor. .

However, as described above, the hydrogenation of the pitch requires the removal of the hydrogenation catalyst after the reaction at a high temperature using an expensive hydrogenation catalyst, thus raising the manufacturing cost of the precursor pitch, and also adding nitrogen to increase the softening point. It has been pointed out that the oxide is expensive, and a uniform reaction cannot be formed in the actual reaction, thereby lowering the melt radioactivity of the prepared pitch precursor.

In addition, a system for preparing a high softening point pitch precursor using a complex of BF ₃ -ether as a polymerization catalyst in a naphtha decomposition residue oil is described in the Korean Fiber Society Conference, 1997, pp. 395. However, in this case, since BF ₃ -ether used as a catalyst is very expensive, there is a problem that it is not suitable for a large scale manufacturing process.

Recently, Korean Patent Application Nos. 1997-0036064, 1997-0036065 and the like have a method of producing isotropic pitches using coal tar pitch and petroleum-based vacuum residues as raw materials, and halogens and halogen compounds as polymerization additives. Is presented.

However, the conventional method described above uses naphtha cracked residue oil as a raw material to produce isotropic pitch precursors for producing carbon fibers with high melt spinning, good oxidation stabilization and high carbonization yield after carbonization under relatively mild conditions in high yield. There is a limit to this.

Particularly, high softening point for isotropic carbon fiber manufacturing isotropic carbon fiber which has excellent properties as precursor pitch by adding halogen and halogen compounds using naphtha cracked residue oil, especially pyrolized fuel oils (PFO), and simply polymerizing and removing low molecular materials as raw materials. There was a problem that it is impossible to produce an isotropic pitch precursor in a high yield of 35% by weight or more.

The present invention is to solve the above problems and to provide a method for producing an isotropic pitch for carbon fibers having a high softening point, and more specifically, after forming a mixture by mixing the petroleum process residue oil and C9 petroleum resin It provides a method for producing an isotropic pitch for carbon fibers by heating and thermally polymerizing the mixture. According to the production method of the present invention, a separate catalyst is not required, and an isotropic pitch for carbon fibers having a high softening point can be produced with a high yield even at a relatively low temperature.

Carbon fiber pitch according to an embodiment of the present invention for achieving the above object comprises the steps of mixing a petroleum process residue oil and C9 petroleum resin to form a mixture; First heating the mixture to induce a chain extension reaction; A second heating step of removing the low boiling point by heating after finishing the first heating; And a third heating step of raising the temperature after finishing the second heating to induce a condensation reaction.

According to the production method of the present invention, since it is excellent in reactivity, an isotropic pitch having a high softening point can be obtained in a high yield even without a separate catalyst.

1 is a SEM photograph of a carbon fiber prepared using the pitch prepared according to Example 1 of the present invention.

The details of other embodiments are included in the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention and the manner of achieving them will be apparent with reference to the embodiments and drawings described hereinafter. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, The present invention is only defined by the scope of the claims.

Hereinafter will be described in detail with respect to the manufacturing method of the pitch for the carbon fiber according to the present invention.

Method for producing a pitch for carbon fiber according to an embodiment of the present invention comprises the steps of 1) mixing the oil process residue oil and C9 petroleum resin to form a mixture; 2) a first heating step of first heating the mixture to induce a chain extension reaction; 3) a second heating step of removing the low boiling point by heating up after the first heating; And 4) a tertiary heating step of raising the temperature after finishing the secondary heating to induce a condensation reaction.

First, 1) the step of mixing the petroleum process residue oil and the C9 petroleum resin to form a mixture will be described.

The petroleum process residue oil and the C9 petroleum resin are added to the reactor and mixed at room temperature.

Here, the petroleum process residue oil is preferably a carbon source of the pitch for carbon fiber, and in the present invention, it is particularly preferable to include pyrolysis fuel oil (PFO) as naphtha decomposition residue oil. The pyrolysis fuel oil (PFO) is produced at the bottom of a naphtha cracking center (NCC), and has a high degree of aroma and abundant resin, which is suitable for the manufacturing method of the present invention.

The pyrolysis fuel oil (PFO) contains various aromatic hydrocarbons, and naphthalene and methylnaphthalene derivatives account for approximately 25 to 35%. Specific examples of the naphthalene and methylnaphthalene derivatives include ethylbenzene, 1-ethenyl-3-methylbenzene, indene, and 1-ethyl-3-methylbenzene. (1-ethyl-3-methyl benzene), 1-methylethylbenzene, 2-ethyl-1,3-dimethylbenzene, propylbenzene , 1-methyl-4- (2-propenyl) -benzene (1-methyl-4- (2-propenyl) benzene), 1,1a, 6,6a-tetrahydro-cyclopropanedene (1,1a, 6,6a-tetrahydro-cycloprop [a] indene), 2-ethyl-1H-indene, 1-methyl-1H-indene, 4,7 -Dimethyl-1H-indene (4,7-dimethyl-1H-indene), 1-methyl-9H-fluorene, 1,7-dimethyl naphthalene , 2-methylindene, 4,4'-dimethyl biphenyl, naphthalene, 4-methyl-1,1'-biphenyl -1,1'-biphenyl), anthracene, 2-methylnaphthalene, 1-methylnaphthalene (1-methylnaphthalene) etc. are mentioned.

In the present invention, the petroleum process residue oil, that is, the carbon source may be a low boiling point is removed. The low boiling point is most volatilized and does not participate in the reaction, so the yield is extremely low as a pitch, and hydrocarbons in the range of C3 to C8 belong to this. In the present invention, when using the carbon source from which the low boiling point is removed, it can be produced in a high softening point pitch with a higher yield.

Meanwhile, the C9 petroleum resin, which is mixed with the petroleum process residue oil of the present invention and reacts with 9 carbon atoms, is specifically styrene, vinyltoluene, indene, alphamethylstyrene, and benzene / toluene / xylene (BTX). ) And so on.

It is preferable that the aroma (fa) of the said C9 petroleum resin of this invention is 40 to 60%. If the aromatization degree is less than 40%, there is a problem of paraffinization and low yield of the product due to the small number of raw materials that can participate in the polymerization reaction, and if more than 60% there is a problem of rapid coking during thermal polymerization.

The C9 petroleum resin in the petroleum process residue oil and the C9 petroleum resin mixture of the present invention is preferably mixed at a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of the petroleum process residue oil. If the content of C9 petroleum resin is less than 10 parts by weight relative to 100 parts by weight of the petroleum process residue oil, there is a problem that the production of the required pitch is difficult due to the low amount of C9 participating in the reaction. There is a problem of undesired products due to the reaction.

Next, 2) the mixture of the petroleum process residue oil and the C9 petroleum resin is first heated to induce a chain extension reaction (first heating step).

In the first heating step, a double bond chain of the C9 petroleum resin is released, and radicals are formed to cause a chain extension reaction in which the petroleum process residue oil and the chain are extended. Compounds having an aromatic structure form bonds through radicals and form a plurality of aromatic structures under a long chain.

It is preferable that heating temperature is 80-100 degreeC here, but when heating temperature is less than 80 degreeC, there exists a problem that radical formation from C9 is impossible, and when it exceeds 100 degreeC, there exists a problem of terminating chain extension reaction.

In addition, it is preferable that the heating time is 1 to 2 hours, but when the heating time is less than 1 hour, there is a problem that sufficient reaction is impossible, and when the heating time is longer than 2 hours, it is solidified during the reaction by crosslinking of the chain structure after completion of the reaction. There is a problem that can be.

Next, 3) after completion of the primary heating to raise the temperature to remove the low boiling point (secondary heating step).

Because coking occurs slowly at the final target temperature (near 360 ° C.) of the thermal polymerization of the present invention, by placing an intermediate temperature section in the second heating step of the present invention, the low boiling point is removed while reducing the coking.

Here, it is preferable that the secondary heating temperature reached by heating up after the primary heating is 250 to 300 ° C. However, when the heating temperature is less than 250 ° C., there is a problem that low boiling point is difficult to remove, and when the heating temperature exceeds 300 ° C., the boiling point is low. In addition to the removal of water there is a problem that the coking reaction may occur.

In addition, it is preferable that the heating time is 1/2 to 2 hours, but when the heating time is less than 1/2 hour, there is a problem that sufficient removal of low boiling point is impossible, and when more than 2 hours, caulking may be started. have.

Next, 4) after the secondary heating, the temperature is raised to induce a condensation reaction (tertiary heating step).

In the third heating step, by reaching the target temperature of the thermal polymerization, the condensation reaction of the petroleum process residue oil and the C9 petroleum resin occurs, and finally a pitch having a high softening point of 240 ° C. or higher, preferably 240 to 300 ° C. Is synthesized.

Here, it is preferable that the third heating temperature reached by heating up after the second heating is 320 to 360 ° C. If the heating temperature is less than 320 ° C., there is a problem that condensation reaction and removal of residual low boiling point are impossible, and 360 ° C. If exceeded, there are problems of reactant loss and coking due to cracking reactions and rapid coking reactions.

In addition, the heating time is preferably 3 to 8 hours, more preferably 3 to 4 hours. There is a problem that the condensation reaction of less than 3 hours of heating time and the removal of the remaining low boiling point is impossible, and if it exceeds 8 hours, there is a problem of coking and cracking.

Hereinafter, preferred embodiments of the present invention are described. The following examples are intended to illustrate the present invention by way of example, and are not intended to limit the scope of the invention.

Example

(1) Preparation of high softening point pitch

Pyrolysis fuel oil (PFO) and C9 petroleum resin were added to the reactor as a carbon source, mixed well, and then thermally polymerized through a first heating, a second heating, and a third heating.

After completion of the thermal polymerization reaction, nitrogen gas was flowed at a flow rate of 1 L / min for 2 hours to remove unreacted or low-reaction molecules, and a desired high softening point optical isotropic pitch was obtained.

The reaction conditions of each Example are as shown in Table 1 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Mixing ratio
(Oil Process Residue: C9 Petroleum Resin) 1: 0.25 1: 0.25 1: 0.25 1: 0.4 1: 0.25 1: 0.25 1: 1 Aromatic Degree of C9 Petroleum Resin
(%) 52 52 44 52 52 81 52 Whether to remove low boilers from oil process residues remove Do not remove remove remove remove remove Do not remove 1st heating time (h) 2 2 One 2 2 2 0.5 Primary heating temperature (℃) 100 100 100 90 100 100 70 2nd heating time (h) One One 2 One One One One Secondary heating temperature (℃) 260 240 260 260 260 290 260 3rd heating time (h) 4 4 4 3 5 4 8 3rd heating temperature (℃) 360 360 330 360 360 400 360

(2) Softening point and yield of obtained pitch

The softening point and the yield of the pitch prepared by the above examples were measured and shown in Table 2 below.

Softening point (℃) of the obtained pitch yield(%) Example 1 270 38 Example 2 268 40 Example 3 281 35 Example 4 258 43 Example 5 326 24 Example 6 344 25 Example 7 More than 350 27

(3) Preparation of Carbon Fiber

Using the pitch synthesized in Example 1, through the spinning, oxidation, carbonization process is a conventional method to produce a carbon fiber.

SEM image of the carbon fiber using the pitch synthesized in Example 1 is shown in Figure 1 (a is a front view, b is a cross-sectional view).

As can be seen in Figure 1, when using the pitch prepared by the optimized synthesis conditions of the present invention, the sphere-shaped incompatibility component is not formed, the finally produced carbon fiber is isotropic.

(4) Tensile strength and modulus test of the manufactured carbon fiber

Table 3 shows the tensile strength and elastic modulus of the carbon fibers a1 to a10 using the pitch synthesized in Example 1.

As can be seen in Table 3, when using a pitch having the optimized synthetic conditions as in Example 1 of the present invention, it was confirmed that the carbon fibers of excellent physical properties having an average tensile strength of 1 GPa, elastic modulus of 56 GPa was produced. .

Load
(N) The tensile strength
(GPa) Tensile strain
(%) Elastic Young's
(GPa) a1 0.2341 1.0015 2.3777 45.6034 a2 0.1456 0.6228 1.8005 37.2215 a3 0.3232 1.3830 2.4544 58.7958 a4 0.2087 0.8931 1.8943 48.2015 a5 0.2355 1.0078 1.5824 65.6378 a6 0.2800 1.1979 1.9017 63.4660 a7 0.1945 0.8321 2.7709 33.3722 a8 0.4029 1.7241 1.6097 116.6022 a9 0.2077 0.8886 1.8540 50.6760 a10 0.1586 0.6786 1.6505 42.0814 Average 0.2391 1.0229 1.9896 56.1658 Standard Deviation 0.08 0.33 0.40 23.77

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

Claims (15)

Mixing the petroleum process residue oil with the C9 petroleum resin to form a mixture;
A primary heating step of primary heating the mixture;
A secondary heating step of raising the temperature after finishing the primary heating; And
A tertiary heating step of raising the temperature after finishing the secondary heating;
Method for producing a pitch for carbon fibers comprising a.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the heating temperature in the first heating step is 80 ~ 100 ℃.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the heating time in the first heating step is 1 to 2 hours.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the chain extension reaction is induced in the first heating step.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the heating temperature in the second heating step is 250 ~ 300 ℃.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the heating time in the second heating step is 1/2 to 2 hours.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the low boiling point is removed in the secondary heating step.
The method of claim 1,
The heating temperature in the third heating step is a manufacturing method of the pitch for carbon fibers, characterized in that 320 ~ 360 ℃.
The method of claim 1,
The heating time in the third heating step is a method for producing a pitch for carbon fibers, characterized in that 3 to 8 hours.
The method of claim 1,
Method for producing a pitch for carbon fibers, characterized in that the condensation reaction occurs in the third heating step.
The method of claim 1,
The petroleum process residue oil is a method for producing a pitch for carbon fibers, characterized in that it comprises naphtha decomposition residue oil.
The method of claim 1,
The petroleum process residue oil is a method for producing a pitch for carbon fibers, characterized in that it comprises a pyrolysis fuel oil (PFO).
The method of claim 1,
The petroleum process residue oil is a method for producing a pitch for carbon fibers, characterized in that it comprises a low boiling point is removed.
The method of claim 1,
The aromatization degree of the C9 petroleum resin is a method for producing a pitch for carbon fibers, characterized in that 40 to 60%.
The method of claim 1,
The C9 petroleum resin in the mixture is a method for producing a pitch for carbon fibers, characterized in that the mixture of 10 to 50 parts by weight relative to 100 parts by weight of the petroleum process residue oil.

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