U.S. patent application number 16/346011 was filed with the patent office on 2020-02-20 for apparatus for manufacturing carbon fiber by using microwaves.
The applicant listed for this patent is LG CHEM, LTD.. Invention is credited to Joon Hee CHO, Myungsu JANG, Ki Hwan KIM, Sujin KIM, Ilha LEE.
Application Number | 20200056306 16/346011 |
Document ID | / |
Family ID | 62626763 |
Filed Date | 2020-02-20 |
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United States Patent
Application |
20200056306 |
Kind Code |
A1 |
KIM; Sujin ; et al. |
February 20, 2020 |
APPARATUS FOR MANUFACTURING CARBON FIBER BY USING MICROWAVES
Abstract
The present invention relates to an apparatus for manufacturing
carbon fiber by using microwaves, and more particularly, to an
apparatus for manufacturing carbon fiber by using microwaves, which
directly or indirectly heats and carbonizes a carbon fiber
precursor by using microwaves, so that energy efficiency is
improved because an entire carbonization furnace is not heated, and
a property of the precursor is adjusted by a simpler method by
using microwaves.
Inventors: |
KIM; Sujin; (Seoul, KR)
; LEE; Ilha; (Seoul, KR) ; CHO; Joon Hee;
(Seoul, KR) ; KIM; Ki Hwan; (Seoul, KR) ;
JANG; Myungsu; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
|
KR |
|
|
Family ID: |
62626763 |
Appl. No.: |
16/346011 |
Filed: |
December 19, 2017 |
PCT Filed: |
December 19, 2017 |
PCT NO: |
PCT/KR2017/015018 |
371 Date: |
April 29, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 9/32 20130101; D01F
9/322 20130101; D06M 10/003 20130101; D01F 9/225 20130101; D10B
2101/12 20130101; D01F 9/22 20130101 |
International
Class: |
D01F 9/32 20060101
D01F009/32; D01F 9/22 20060101 D01F009/22; D06M 10/00 20060101
D06M010/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2016 |
KR |
10-2016-0173883 |
Claims
1. An apparatus for manufacturing carbon fiber by using microwaves,
the apparatus comprising: a heat treatment furnace which stabilizes
a precursor; and a carbonization furnace which is positioned at one
side of the heat treatment furnace and carbonizes the stabilized
precursor, wherein the carbonization furnace carbonizes the
precursor by using microwaves as a heat source.
2. The apparatus of claim 1, wherein the carbonization furnace
includes: a main body; a micro emitting unit which is positioned
inside or outside the main body, and emits microwaves to the
stabilized precursor; and a heating body which is positioned inside
the main body and is heated by the microwaves.
3. The apparatus of claim 2, wherein the heating body occupies 0.1%
to 5% of a volume of the main body.
4. The apparatus of claim 1, wherein one or more carbonization
furnaces are positioned at one side of the heat treatment
furnace.
5. The apparatus of claim 1, further comprising rollers positioned
at one side and the opposing side of each of the heat treatment
furnace and the carbonization furnace.
6. The apparatus of claim 1, wherein the carbonization furnace is
configured to produce carbonization temperature of 400.degree. C.
to 1,500.degree. C.
Description
[0001] The present application is a National Stage entry of
International Application No. PCT/KR2017/015018, filed Dec. 19,
2017, and claims priority to and the benefit of Korean Patent
Application No. 10-2016-0173883 filed in the Korean Intellectual
Property Office on Dec. 19, 2016, the entire contents of which are
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to an apparatus for
manufacturing carbon fiber by using microwaves. More particularly,
the present invention relates to an apparatus and techniques for
manufacturing carbon fiber by using microwaves which directly or
indirectly heats and carbonizes a carbon fiber precursor, so that
energy efficiency is improved because an entirety of a
carbonization furnace is not heated, and a property of the
precursor is adjusted by a simpler method by the microwaves.
BACKGROUND ART
[0003] Carbon fiber can be obtained by pyrolyzing an organic
precursor material in the form of fiber manufactured from
polyacrylonitrile (PAN), pitch that is a petroleum-based/coal-based
hydrocarbon residue, or rayon that is a carbon material of a fiber
sheet in which a mass content of carbon elements is 90% or more, in
an inert atmosphere.
[0004] The carbon fiber is lighter than steel and has excellent
strength, so that the carbon fiber is widely applied to various
fields, such as the automotive field, the aerospace field, the wind
power generation field, and the sports field. For example,
recently, environmental regulations related to exhaust gas of a
vehicle have been tightened due to environmental concerns, so that
a light vehicle having high efficiency has been in increasing
demand. Thus, a method of decreasing weight of a vehicle without
sacrificing structural and mechanical strength, by using a carbon
fiber reinforced composites has attracted attention.
[0005] However, since carbon fiber is expensive, the
commercialization of carbon fiber is limited, and thus, there is an
urgent demand for a development of a technology for mass producing
carbon fiber having high performance at low cost.
[0006] A process of carbonizing carbon fiber in the related art is
performed by heat treatment at a high temperature of 1,000.degree.
C. to 1,500.degree. C. by using an electric carbonization furnace.
The electric carbonization furnace is generally divided into two or
more heat zones including a heat zone for a low temperature and a
heat zone for a high temperature. The carbonization process using
the electric carbonization furnace has a scheme in which heat is
transmitted to carbon fiber by an internal temperature of the
carbonization furnace or heat moves in a direction from an outer
side to an inner side of the fiber, so that there is a problem in
that energy efficiency is not high.
[0007] Further, the carbonization process in the related art is a
scheme in which the entirety of the carbonization furnace is heated
in order to increase an internal temperature of the carbonization
furnace, and a temperature of a heating furnace needs to be
maintained higher than a carbonization temperature of a precursor,
so there is a problem in that heat resistance is required.
[0008] In relation to this, there is a need for a process of
carbonizing carbon fiber having high energy efficiency.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
[0009] The present invention is conceived to solve the foregoing
problems, and an object of the present invention is to provide an
apparatus for manufacturing carbonized fiber using microwaves,
which includes a carbonization furnace that directly heats a
precursor by using microwaves in order to improve energy
efficiency.
[0010] Another object of the present invention is to provide an
apparatus for manufacturing carbonized fiber using microwaves,
which includes a heating body heated by microwaves inside a main
body of a carbonization furnace in order to carbonize stabilized
fiber having low reactivity to microwaves and increase energy
efficiency for heating compared to a carbonization process of
heating an entirety of a carbonization furnace in the related
art.
Technical Solution
[0011] An apparatus for manufacturing carbonized fiber by using
microwaves according to the present invention includes: a heat
treatment furnace which stabilizes a precursor; and a carbonization
furnace which is positioned at one side of the heat treatment
furnace and carbonizes the stabilized precursor, in which the
carbonization furnace carbonizes the precursor by using microwaves
as a heat source.
[0012] The carbonization furnace may include: a main body; a micro
emitting unit which is positioned inside or outside the main body,
and emits microwaves to the stabilized precursor; and a heating
body which is positioned inside the main body and is heated by the
microwaves.
[0013] The heating body may occupy 0.1% to 5% of a volume of the
main body.
[0014] One or more carbonization furnaces may be positioned at one
side of the heat treatment furnace.
[0015] A continuous process may be performed by using rollers
positioned at one side and the other side of each of the heat
treatment furnace and the carbonization furnace.
[0016] The carbonization furnace may have a carbonization
temperature of 400.degree. C. to 1,500.degree. C.
Advantageous Effects
[0017] According to the present invention, the carbonization
furnace includes the emitting unit that emits microwaves inside or
outside thereof and directly/indirectly heats the fiber passing the
stabilization fiber to increase a carbonization speed of carbon
fiber, so that the carbon fiber is obtained within a short time,
thereby achieving increased energy efficiency.
[0018] Further, the carbonization furnace includes the heating body
therein, so that there is no limit in the kind of precursor used
for manufacturing the carbonized fiber, and the precursor is
indirectly heated while the entirety of the carbonization furnace
is not heated, thereby achieving increased energy efficiency
compared to the carbonization process in the related art.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a cross-sectional view of a carbon fiber
manufacturing apparatus using microwaves according to an exemplary
embodiment of the present invention.
[0020] FIG. 2 is a cross-sectional view of a carbonization furnace
according to the exemplary embodiment of the present invention.
[0021] FIG. 3 is a perspective view of a heating body according to
the exemplary embodiment of the present invention.
DETAILED DESCRIPTION
[0022] The present invention will be described in detail with
reference to the accompanying drawings. Herein, repeated and
detailed description of publicly known functions and configurations
which may unnecessarily make the main point of the present
invention unclear will be omitted. The exemplary embodiments of the
present invention are provided for more completely explaining the
present invention to those skilled in the art. Accordingly, shapes,
sizes, and the like of the elements in the drawings may be
exaggerated for clarity of the description.
[0023] In the entire specification, unless explicitly described to
the contrary, when it is said that a part "comprises/includes" a
constituent element, this means that another constituent element
may be further "included/comprised", not that another constituent
element is excluded.
[0024] Hereinafter, an exemplary embodiment is presented for
helping understanding of the present invention. However, the
exemplary embodiment below is simply provided for more easy
understanding of the present invention, and the contents of the
present invention are not limited by the exemplary embodiment.
[0025] <Carbon Fiber Manufacturing Apparatus Using
Microwave>
[0026] FIG. 1 is a cross-sectional view of a carbon fiber
manufacturing apparatus 100 using microwaves according to an
exemplary embodiment of the present invention. The carbon fiber
manufacturing apparatus 100 using the microwaves may include a heat
treatment furnace 10 and a carbonization furnace 20, and a process
may be continuously performed by rollers positioned at one side and
the other side of each of the heat treatment furnace 10 and the
carbonization furnace 20.
[0027] The heat treatment furnace 10 is configured to stablilize a
precursor, and may serve to make the precursor be in contact with
air and oxidize the precursor. The process of stabilizing the
precursor is a process of insolubilizing the precursor so as to
have flame resistance when the precursor is carbonized. The
stabilization of the precursor may provide an inner side of the
heat treatment furnace 10 with an air atmosphere, and heat treat
the precursor at a temperature of 200.degree. C. to 300.degree. C.
for one to two hours to stabilize a fiber structure of the
precursor. In this case, when a stabilization reaction of the
precursor progresses, the stabilization may sharply progress, so
that it is noted that the temperature is increased to 200.degree.
C. to 300.degree. C. by stages. When the stabilization condition of
the precursor is 200.degree. C. or lower and less than one hour,
there may be a problem in that oxidization and stabilization are
inadequate, and when the stabilization condition of the precursor
is higher than 300.degree. C. and longer than two hours, a property
of the carbonized fiber may be negatively influenced, so that there
may be a problem in energy loss.
[0028] Herein, the precursor may be formed of a composition of any
one of a rayon-series material, a pitch-series material, a
polyacrylonitrile-series material, and a cellulose-series
material.
[0029] The carbonization furnace 20 is configured to carbonize the
stabilized precursor, and may carbonize the precursor by using
microwaves as a heat source. During the carbonization process, the
carbonization furnace may carbonize the precursor at a temperature
of 400.degree. C. to 1,500.degree. C., and in this case, the
carbonization process may be divided into low-temperature
carbonization and high-temperature carbonization. The
low-temperature carbonization may carbonize the precursor at a
temperature of 400.degree. C. to 900.degree. C., and the
high-temperature carbonization process may carbonize the precursor
at a temperature of 900.degree. C. to 1,500.degree. C.
[0030] Further, the carbonization furnace 20 may be positioned at
one side of the heat treatment furnace 10, and may include a main
body 21 and a micro emitting unit 22 for carbonizing the stabilized
precursor.
[0031] The main body 21 may mean a space in which a temperature is
increased by the micro emitting unit 22 which is to be described
below.
[0032] The micro emitting unit 22 may be installed outside or
inside an outer circumference surface of the main body and serve to
emit microwaves onto the stabilized precursor. By adjusting an
energy intensity (output), an energy emission time, and the like,
of the microwaves according to the present invention, the carbon
fiber having a required property may be irradiated with a high
yield within a shorter reaction time.
[0033] Further, the carbonization furnace 20 according to the
present invention may carbonize the precursor by directly heating
the stabilized precursor by the microwaves to manufacture the
carbon fiber. In the carbonization furnace 20 according to the
present invention, the microwaves directly heat the precursor
without heating the main body unlike the carbonization technology
in the related art, thereby achieving an advantage in that energy
efficiency is improved compared to the carbonization process in the
related art.
[0034] FIG. 2 is a cross-sectional view of the carbonization
furnace 20 according to the exemplary embodiment of the present
invention, and FIG. 3 is a perspective view of a heating body 23
according to the exemplary embodiment of the present invention. The
carbonization furnace 20 according to the present invention may
further include the heating body 23. The heating body 23 may be
positioned inside the main body 21, and is directly heated by the
microwaves emitted from the micro emitting unit 22 to serve to
indirectly carbonize the precursor. Further, the heating body may
be formed of a composition of any one of silicon carbide, silicon,
a metal silicide, carbon, and a carbon fiber composite
material.
[0035] In this case, the main body 21 is the configuration
including any one or more of the micro emitting unit 22 and the
heating body 23, and it is noted that the configurations, such as a
manipulating unit and an operating unit, additionally configurable
in the carbonization process are not included inside the main body
21. According to some exemplary embodiments, the main body 21 may
be formed at a position with a size in which only the heating body
23 may be included.
[0036] The heating body 23 is formed with an inlet through which
the precursor enters and an outlet through which the carbon fiber
formed by carbonizing the precursor is discharged. The inner side
of the heating body 23 may be provided with an atmosphere of gas,
such as nitrogen, argon, and helium or mixed gas thereof, and
preferably, the carbonization process may be formed in a nitrogen
atmosphere. For example, the precursor stabilized in the heat
treatment furnace 10 may be inserted into the heating body 23 in
the nitrogen atmosphere, the heating body 23 is heated to a
temperature of 400.degree. C. to 1,500.degree. C. by the microwaves
emitted by the micro emitting unit 22, and then, the precursor may
be indirectly heated by radiant heat of the heating body 23.
[0037] Herein, the carbonization furnace 20 according to the
present invention carbonizes the precursor by using the indirect
heating, thereby achieving an advantage in that even the stabilized
fiber having low reactivity to the microwaves may be carbonized,
and achieving an effect in that it is possible to improve a
property and energy efficiency of the manufactured carbon fiber
according to a structure and a volume of the heating body 23.
[0038] It is noted that as long as the heating body 23 has a volume
of 0.1% to 5% of a volume of the main body 21, the form of the
heating body 23 is not limited. When the volume of the heating body
23 exceeds 5%, a large amount of microwaves needs to be emitted for
heating the heating body 23, and a temperature inside the
carbonization furnace 20 is not increased and tensile strength and
modulus of the carbon fiber are decreased, so that there may be a
problem in that energy efficiency of the carbonization process is
decreased.
[0039] FIG. 3 illustrates an example of the form of the heating
body 23 according to the present invention. A structure of the
heating body 23 may have a shape of any one of a plate and a hollow
column structure. For example, when the structure of the heating
body 23 is provided in a plate shape, one or more plates may be
provided, the heating body 23 may be formed of only one surface or
two upper and lower surfaces. Further, the heating body 23 may be
formed of three surfaces including any one of upper/lower/right
surfaces and upper/lower/left surfaces. When the heating body 23 is
provided in the plate shape, one or more holes may be formed in a
part of the plate, and the hole may have a form of any one of a
circle, a polygon, and an ellipse, but it is noted that the form of
the hole is not limited. Further, according to some exemplary
embodiments, the heating body 23 may be provided in a plate shaped
like a net.
[0040] Further, the heating body 23 may have the form of a hollow
column and a cross section of the column may have the form of any
one of a circle, a quadrangle, a polygon, and an ellipse, but it is
noted that the form of the cross section of the column of the
heating body is not limited. Herein, when the heating body 23 is
provided in a three-dimensional shape, the surface forming the
shape may be formed with one or more holes, and the hole may have
the form of any one of a circle, a polygon, and an ellipse, but it
is noted that the form of the hole is not limited thereto. In this
case, a space in which the precursor is accommodated may be divided
into two or more spaces, and an inlet through which the precursor
enters and an outlet through which the precursor is taken out may
be formed in the divided spaces, respectively. The division of the
accommodation space of the precursor in the heating body 23
complexly enables the direct heating and the indirect heating of
the precursor and increases a movement distance of the precursor,
so that the precursor is irradiated by the microwaves or the
radiant heat of the heating body for a long time and is carbonized
and graphitized, thereby minimizing external and internal
temperature gradients and achieving an effect in that a generation
of a crack in the carbon fiber is decreased.
[0041] Further, the carbonization furnace 20 may further include a
chamber (not illustrated) including all of the main body 21, the
micro emitting unit 22, and the heating body 23 inside thereof. The
chamber may be positioned outside the main body 21, and when the
chamber may further include the configuration, for example, a
manipulating unit and an operating unit, required for the
carbonization of the precursor, in addition to the main body 21,
the micro emitting unit 22, and the heating body 23, a shape and a
size of the chamber are not limited.
[0042] Further, one or more carbonization furnaces 20 may be
positioned at one side of the heat treatment furnace 10. One or
more carbonization furnaces 20 are serially connected, so that a
movement distance of the precursor within the carbonization furnace
20 is increased and the precursor is irradiated by the microwaves
for a long time and is carbonized or graphitized to manufacture
carbon fiber. One or more carbonization furnaces 20 are serially
connected, so that only the outer surface of the precursor is
heated by the high-temperature microwave radiant heat in a moment
and the inner side of the precursor is not heated, thereby solving
the problem in that a large temperature gradient between the inner
side and the outer side is generated.
Experimental Example 1
[0043] Tensile strength and modulus were compared by using carbon
fiber manufactured by using a carbonization furnace including a
heating body having a volume of about 8% of a volume of a main body
and the carbon fiber manufactured by using the carbonization
furnace including the heating body having a volume of about 0.1% to
5% of a volume of the main body according to the exemplary
embodiment of the present invention.
[0044] To this end, an experiment was performed on one carbon fiber
product manufactured by using the carbonization furnace including
the heating body having the volume of about 8% and two carbon fiber
products according to the exemplary embodiment of the present
invention.
[0045] In Comparative Example 1, Example 1, and Example 2,
polyacrylonitrile fiber was prepared as a precursor and was heat
treated in an air atmosphere at a temperature of 280.degree. C. for
two hours.
[0046] In Comparative Example 1, stabilized polyacrylonitrile fiber
was inserted into a carbonization furnace including a heating body
having a volume corresponding to about 8% of a volume of a main
body and then a carbonization process was performed in a nitrogen
atmosphere at a temperature of 800.degree. C. to 1,500.degree. C.
for 20 minutes or longer. In this case, applied power of microwaves
was set to 1.2 kW.
[0047] In Example 1, stabilized polyacrylonitrile fiber was
inserted into a carbonization furnace including a heating body
having a volume corresponding to about 0.13% of a volume of a main
body and then a carbonization process was performed in a nitrogen
atmosphere at a temperature of 800.degree. C. to 1,500.degree. C.
within one minute. In this case, applied power of microwaves was
set to 1 kW. Further, in Example 2, stabilized polyacrylonitrile
fiber was inserted to a carbonization furnace including a heating
body having a volume corresponding to about 1.8% of a volume of a
main body and then a carbonization process was performed in a
nitrogen atmosphere at a temperature of 800.degree. C. to
1,500.degree. C. within five minutes, and applied power of
microwaves was set to 1.8 kW.
[0048] In order to compare a mechanical property after the
carbonization, tensile strength and elasticity of one string of the
fiber were repeatedly measured by about 50 times using a Favimat
tester and an average of the measured tensile strength and
elasticity were calculated.
TABLE-US-00001 TABLE 1 Comparative Example 1 Example 2 Example 1
Carbon Volume (%) of 0.13 1.8 8.6 condition heating body Applied
power 1 1.8 1.2 (kW) Time (min) 1 <5 >20 Carbon Tensile
>2.5 >2.5 ~1.5 fiber strength property Modulus >190
>180 ~90
[0049] Referring to the Table above, in Comparative Example 1, 20
minutes or longer are required for increasing a temperature of the
heating body to 800.degree. C. to 1,500.degree. C., and due to the
large volume of the heating body and the long heating time, the
tensile strength of the carbon fiber was measured to be 1.5 or less
and modulus of the carbon fiber was measured at 90 or less.
Accordingly, it can be seen that when the volume of the heating
body is large, elasticity of the manufactured carbon fiber is
inadequate, and energy efficiency of the production of the carbon
fiber is degraded.
[0050] In order to increase a temperature of the heating body to
800.degree. C. to 1,500.degree. C., one minute is required in
Example 1 and five minutes or less is required in Example 2. In
this case, tensile strength and modulus of the carbon fiber of
Example 1 and Example 2 are 2.5 or more and 190 or more, so that it
can be seen that elasticity of the carbon fiber is excellent, and
energy efficiency improved.
[0051] As a result, according to the determination based on the
result, it can be seen that the volume of the heating body is
closely related to the properties of the carbon fiber and the
energy efficiency of its production. As the volume of the heating
body is small, the heating body is heated evenly by a small output
of the microwaves within a short time, so that the tensile strength
and the modulus of the carbon fiber are increased.
Experimental Example 2
[0052] Temperatures were compared between Comparative Example 2,
that is a carbonization furnace including no heating body, and
Example 3, that is the carbonization furnace including the heating
body having the volume of 0.1% to 5% of the volume of the main body
according to the exemplary embodiment of the present invention.
Herein, the heating body of Example 3 includes silicon carbide
(SiC) having a volume corresponding to about 0.13% of a volume of a
main body.
[0053] The carbonization furnaces of Comparative Example 2 and
Example 3 have the same size, and a time at which an internal
temperature of the carbonization furnace reaches 1,000.degree. C.
by applying microwaves of 1.2 kW was measured.
TABLE-US-00002 TABLE 2 Comparative Example 2 Example 3 Presence of
x .smallcircle. heating body Reach time at Not reached 2
1,000.degree. C. (minute)
[0054] Referring to the Table, it can be seen that in Comparative
Example 2, the carbonization furnace has a temperature lower than
300.degree. C. even after ten minutes, but in Example 3, the
carbonization furnace reaches a temperature of 1,000.degree. C.
after two minutes.
[0055] That is, in Comparative Example 2, the carbonization furnace
fails to reach the temperature at which the stabilized fiber
becomes fiber having high reactivity to microwaves, and in Example
3, the temperature inside the carbonization furnace reaches a
temperature region in which fiber having high reactivity to
microwaves is manufactured by only the heating body within a short
time, so that it is possible to effectively manufacture carbonized
fiber.
[0056] Accordingly, when the stabilized fiber passing the
stabilization operation in the heat treatment furnace moves to the
carbonization furnace, the stabilized fiber enters the region in
which the stabilized fiber has high reactivity to the microwaves at
a high speed by an increase in a temperature of the heating body,
so that energy efficiency is improved and a carbonization property
of the carbon fiber is adjusted by a simpler method by the use of
microwaves.
[0057] The present invention has been described with reference to
the exemplary embodiment of the present invention, but those
skilled in the art may appreciate that the present invention may be
variously corrected and changed within the range without departing
from the spirit and the area of the present invention described in
the appending claims.
* * * * *