KR102437438B1 - High Strength Carbon Fiber Using Electron Beam Irradiation and Manufacturing Method Thereof - Google Patents

Abstract

The method for manufacturing high-strength carbon fiber using electron beam irradiation according to the present invention,
A first step of disposing the carbon fiber to maintain a constant tension in a continuous electron beam irradiator; By irradiating an electron beam with a dose of 50 kGy to 400 kGy with a strength of 0.1 MeV to 5.0 MeV to the carbon fiber, the surface defects of the carbon fiber at a dose of 50 kGy to 200 kGy are primarily eliminated, and the interior of the carbon fiber at a dose of 200 kGy to 400 kGy a second step of secondary elimination of voids; and a third step of recovering the carbon fiber treated with electron beam irradiation. Using the method for manufacturing high-strength carbon fiber using electron beam irradiation according to the present invention, high-strength carbon fiber can be manufactured quickly and economically.

Description

High Strength Carbon Fiber Using Electron Beam Irradiation and Manufacturing Method Thereof

The present invention relates to a high-strength carbon fiber using electron beam irradiation and a method for manufacturing the same.

Carbon fiber is a fiber composed of long molecular chains in which numerous carbon atoms form a crystal structure, and is a fiber with high tensile strength, excellent resistance to high temperature and chemicals, and low thermal expansion.

Carbon fibers are classified into PAN-based carbon fibers, pitch-based carbon fibers, and cellulose-based carbon fibers according to raw materials. Among them, PAN-based carbon fiber is the most widely used carbon fiber.

The PAN-based carbon fiber manufacturing process consists of precursor synthesis, spinning, stretching, stabilization, carbonization, and surface treatment.

PAN-based carbon fiber is spun through a nozzle, and damage occurs due to surface friction in the spinning process, and damage by roller friction in the stretching process. In addition, during the stabilization and carbonization process, pores are generated due to defects in the internal structure.

The various defects generated in this way promote the formation and growth of non-uniform stress distribution, stress concentration in a specific part, and microporosity, and eventually lead to overall defects, which is an obstacle to the development of high-strength carbon fiber.

In order to solve this problem, in Japanese Patent (4350260), Japanese Patent Laid-Open (1993-214614), Japanese Registered Patent (2817232), Japanese Patent Laid-Open (2002-371461), etc., carbon fibers are irradiated with electron beams. method to eliminate the defects of

However, the electron beam irradiation methods disclosed in these patents simply eliminate defects on the surface of carbon fibers, or the carbon fiber defect removal time is too long due to excessive irradiation dose, or the internal structure of carbon fibers is destroyed due to excessive irradiation dose. There is a problem in that the defects are rather increased, so it cannot be applied to actually remove the defects of carbon fiber.

Japanese registered patent (4350260) Japanese Laid-Open Patent (1993-214614) Japanese registered patent (2817232) Japanese Laid-Open Patent (2002-371461)

It is an object of the present invention to provide a high-strength carbon fiber using electron beam irradiation and a method for manufacturing the same, which can solve the above problems.

In order to achieve the above object, a method for manufacturing high-strength carbon fiber using electron beam irradiation,
In order to find the electron beam strength and electron beam dose that can remove both surface defects and internal voids of carbon fiber, step 1-1 to find the electron beam strength and electron beam dose to eliminate surface defects of carbon fiber, and internal voids of carbon fiber A first step consisting of steps 1-2 to find the electron beam intensity and electron beam dose to eliminate
With the electron beam strength and electron beam dose found in the first step, the surface defects and internal voids of the carbon fiber treated with electron beam irradiation were examined by an electron microscope or Raman spectroscopy method, and the electron beam strength and electron beam dose found in the first step were carbon a second step of confirming that the strength of the electron beam and the dose of the electron beam to reduce the surface defects and internal voids of the fiber; and
A third step of irradiating the carbon fiber with the electron beam intensity and the electron beam dose confirmed in the second step,
The electron beam intensity was increased from 0.1MeV to 5.0MeV in step 1-1, the electron beam dose was decreased from 400kGy to 50kGy, and the electron beam intensity was decreased from 5.0MeV to 0.1MeV in step 1-2, and the electron beam dose is increased from 50 kGy to 400 kGy, or

In step 1-1, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV, the electron beam dose is increased from 50 kGy to 400 kGy, and in the first-2 step, the electron beam intensity is increased from 0.1 MeV to 5.0 MeV, and the electron beam dose is increased. is characterized in that it is reduced from 400 kGy to 50 kGy.

delete

delete

delete

The above object is achieved by a high-strength carbon fiber manufactured by the above-described method for manufacturing high-strength carbon fiber using electron beam irradiation.

The present invention removes the surface defects of carbon fibers and internal defects (internal voids) of carbon fibers step by step by adjusting the electron beam intensity and/or the electron beam dose step by step. For this reason, conventionally, only the defects generated on the surface of the carbon fiber are simply removed with an electron beam, the carbon fiber defect removal time is too long due to the conventional excessive radiation dose, or the internal structure of the carbon fiber is collapsed due to the conventional excessive radiation dose, so that the defects are rather More problems can be solved all at once.

Using the method for manufacturing high-strength carbon fiber using electron beam irradiation according to the present invention, high-strength carbon fiber can be manufactured quickly and economically.

1 is a flowchart illustrating a method for manufacturing high-strength carbon fiber using electron beam irradiation according to an embodiment of the present invention.
2 is a view showing a continuous electron beam irradiator for performing the high-strength carbon fiber manufacturing method shown in FIG.
FIG. 3 is a schematic diagram for explaining the second step shown in FIG. 1 .
Figure 4 is an electron microscope photograph of carbon fiber to determine the carbon fiber surface defect removal state according to the electron beam dose, Figure 4 (a) is an electron microscope photograph of the carbon fiber before the electron beam irradiation treatment, Figure 4 (b) is Carbon fiber treated with electron beam irradiation at an electron beam dose of 100 kGy, Fig. 4 (c) is a carbon fiber treated with electron beam irradiation at an electron beam dose of 200 kGy, Fig. 4 (d) is a carbon fiber treated with electron beam irradiation at an electron beam dose of 300 kGy, Fig. 4 (e) is a carbon fiber irradiated with an electron beam at an electron beam dose of 400 kGy, and FIG. 4 (f) is a photograph taken with an electron microscope of a carbon fiber irradiated with an electron beam at an electron beam dose of 500 kGy.
5 is a Raman spectrum according to an electron beam dose.
6 is a graph showing the area ratio (I _A /I _G ) of the A band and the G band shown in FIG. 5 and the area ratio of the D band and the G band (I _D /I _G ) according to the electron beam dose.
7 is a graph showing changes in the tensile strength and tensile modulus of carbon fiber according to the electron beam dose.
8 is a graph showing the change in the carbon fiber interfacial shear strength according to the electron beam dose.

Hereinafter, a method for manufacturing high-strength carbon fiber using electron beam irradiation according to an embodiment of the present invention will be described in detail.

As shown in Figure 1, the method for manufacturing high-strength carbon fiber using electron beam irradiation according to an embodiment of the present invention,
In order to find the electron beam strength and electron beam dose that can remove both surface defects and internal voids of carbon fiber, step 1-1 to find the electron beam strength and electron beam dose to eliminate surface defects of carbon fiber, and internal voids of carbon fiber A first step (S11) consisting of the first 1-2 steps to find the electron beam intensity and electron beam dose to eliminate the;
With the electron beam strength and electron beam dose found in the first step, the surface defects and internal voids of the carbon fiber treated with electron beam irradiation were examined by an electron microscope or Raman spectroscopy method, and the electron beam strength and electron beam dose found in the first step were carbon a second step (S12) of checking whether the strength of the electron beam and the dose of the electron beam to reduce surface defects and internal voids of the fiber; and
A third step (S13) of irradiating the carbon fiber with the electron beam intensity and the electron beam dose confirmed in the second step,
The electron beam intensity was increased from 0.1MeV to 5.0MeV in step 1-1, the electron beam dose was decreased from 400kGy to 50kGy, and the electron beam intensity was decreased from 5.0MeV to 0.1MeV in step 1-2, and the electron beam dose is increased from 50 kGy to 400 kGy, or

In step 1-1, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV, the electron beam dose is increased from 50 kGy to 400 kGy, and in the first-2 step, the electron beam intensity is increased from 0.1 MeV to 5.0 MeV, and the electron beam dose is increased. is characterized in that it is reduced from 400 kGy to 50 kGy.

delete

delete

delete

Prior to describing the first step (S11) to the third step (S13), a continuous electron beam irradiator for performing the first step (S11) to the third step (S13) will be described.

As shown in FIG. 2 , the continuous electron beam irradiator 1 is composed of a supply unit 10 , a guide unit 20 , a recovery unit 30 , and an electron beam irradiation unit 40 .

The supply unit 10 supplies the carbon fibers (CF1) in the longitudinal direction. Carbon fibers (CF1) are composed of 1 to 48k filaments. The supply unit 10 is composed of a supply roller 11 on which the carbon fibers CF1 are wound, and a driving unit (not shown) for rotating the supply roller 11 . Since the driving unit can be implemented by known technology, a detailed description thereof will be omitted.

The guide unit 20 guides the carbon fiber CF1 from the supply unit 10 to the recovery unit 30 . The guide unit 20 includes a lower guide roller 21 , an upper guide roller 22 , a lower guide roller 21 and a shaft (not shown) that rotatably supports the upper guide roller 22 .

The recovery unit 30 winds and recovers the carbon fiber (CF2) that has been irradiated with electron beams. In FIG. 2, for convenience of illustration, carbon fibers (CF1, black) and carbon fibers (CF2, brown) treated with electron beam irradiation before electron beam irradiation were separated by reference numerals and colors. The recovery unit 30 includes a recovery roller 31 on which the carbon fiber (CF2) on which electron beam irradiation has been completed is wound, and a driving unit (not shown) that rotates the recovery roller 31 . Since the driving unit can be implemented by known technology, a detailed description thereof will be omitted.

The electron beam irradiation unit 40 is composed of an irradiator 41 for irradiating an electron beam, and a controller 42 for controlling the intensity, dose, and irradiation time of the electron beam irradiated from the irradiator 41 . Since the irradiator 41 is a known device, a detailed description thereof will be omitted. Additional functions of the control unit 42 will be described later.

When irradiated with an electron beam, heat of less than 150°C may be generated.

In consideration of this, it is preferable that the irradiator 41 irradiate the electron beam to the carbon fiber in an air atmosphere at room temperature or an air atmosphere below 480° C. where oxidation of the carbon fiber starts. The reason is that although the effect of electron beam irradiation is effective even at low (zero) and high temperature (500° C. or higher), low temperature lowers the activity of radicals generated by electron beam treatment, which can interfere with the repair of defects inside the carbon fiber, and high temperature atmosphere This is because it is undesirable due to an increase in system equipment cost, etc.

Hereinafter, the first step (S11) will be described.

In order to find the electron beam strength and electron beam dose that can remove both surface defects and internal voids of carbon fiber, step 1-1 to find the electron beam strength and electron beam dose to eliminate surface defects of carbon fiber, and internal voids of carbon fiber It consists of steps 1-2 to find the electron beam intensity and the electron beam dose to eliminate
And, the electron beam intensity is increased from 0.1MeV to 5.0MeV in step 1-1, the electron beam dose is decreased from 400kGy to 50kGy, and the electron beam intensity is decreased from 5.0MeV to 0.1MeV in step 1-2, The electron beam dose is increased from 50 kGy to 400 kGy.
Alternatively, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV in step 1-1, the electron beam dose is increased from 50 kGy to 400 kGy, and the electron beam intensity is increased from 0.1 MeV to 5.0 MeV in step 1-2, Reduce the electron beam dose from 400 kGy to 50 kGy.
Carbon fibers (CF1, CF2) are PAN-based carbon fibers. Of course, pitch-based carbon fibers and cellulose-based carbon fibers may also be used.

Carbon fibers (CF1, CF2) are placed in a state in which tensile force is applied to the continuous electron beam irradiator (1). The tensile force is applied in a line that does not exceed the tensile strength of the carbon fibers (CF1, CF2) so that the carbon fibers (CF1, CF2) do not break. The tensile force is controlled by the relative rotational speed of the supply roller 11 and the recovery roller 31 .

The reason for applying a tensile force to the carbon fiber is to prevent the filaments constituting the carbon fiber from aggregating with each other, and uniformly irradiating the electron beam to the filament constituting the carbon fiber (CF1) in the second step (S12).

delete

Hereinafter, the second step (S12) will be described.
Using the electron beam intensity and electron beam dose found in the first step (S11), the surface defects and internal voids of the carbon fiber treated with electron beam irradiation were examined by an electron microscope or Raman spectroscopy method, and the electron beam strength and electron beam found in the first step (S11) Check that the dose is the same as the strength of the electron beam that reduces the surface defects and internal voids of the carbon fiber.
Hereinafter, the third step (S13) will be described.
With the electron beam strength and electron beam dose confirmed in the second step (S22), the carbon fiber (CF1) is irradiated with an electron beam at a constant electron beam intensity for a certain period of time to eliminate structural defects of the carbon fiber.

delete

To this end, the irradiator 41 irradiates the carbon fiber (CF1) with an electron beam of a dose of 50 kGy to 400 kGy with an intensity of 0.1 MeV to 5.0 MeV, and primarily eliminates the surface defects of the carbon fiber (CF1) at a dose of 50 kGy to 200 kGy. , then, by additionally irradiating the carbon fiber ((CF1) with an electron beam, the internal voids (internal defects) of the carbon fiber (CF1) are secondaryly eliminated at a dose of 200 kGy to 400 kGy.

More preferably, the carbon fiber (CF1) is irradiated with an electron beam at a dose of 100 kGy to 300 kGy with an electron beam intensity of 1.5 MeV, and the surface defects of the carbon fiber (CF1) at a dose of 100 kGy to 200 kGy are primarily eliminated, and then an irradiator ( 41) further irradiates the carbon fiber ((CF1) with an electron beam to secondaryly eliminate the internal voids of the carbon fiber (CF1) at a dose of 200 kGy to 300 kGy. Due to this, the surface defects and internal voids are removed from the carbon fiber (CF1). high-strength carbon fiber (CF2) is made.

It is a technical feature of the present invention to remove surface defects and internal voids of carbon fiber (CF) step by step by irradiating electron beams with different doses of electron beams caught in the first and second phases.

The reason that the irradiator 41 irradiates the carbon fiber (CF1) with an electron beam of a dose of 50 kGy to 400 kGy with an intensity of 0.1 to 5.0 MeV is that the electron beam strength is 0.1 MeV If it is less than, the electron beam treatment is insufficient to eliminate the defects of the carbon fiber (CF), and if the electron beam strength exceeds 5.0 MeV, the carbon fiber may be ignited and damaged.

In addition, when the electron beam dose is less than 50 kGy, the electron beam treatment effect of the carbon fiber is insufficient to eliminate the defects of the carbon fiber (CF), and when the electron beam dose exceeds 400 kGy, the carbon fiber may have more defects . Conventionally, these problems are not taken into account at all, and by irradiating the carbon fiber with an electron beam of too much dose to the carbon fiber, the defect of the carbon fiber is rather generated rather than eliminated.

In addition, it is preferable that the irradiator 41 irradiate the electron beam to the carbon fiber in an air atmosphere at room temperature or an air atmosphere below 480° C. where oxidation of the carbon fiber starts. The reason is the same as described above.

line hump

As shown in FIG. 3(b), the surface defects of carbon fibers are removed at an electron beam dose of 50 kGy to 200 kGy. As the surface defects are removed in this way, as shown in FIG. 4 , the pattern in the axial direction of the carbon fiber changes. That is, the pattern in the axial direction of the carbon fiber before the electron beam irradiation treatment shown in FIG. 4( a ) becomes clear again after it fades in the range of 100 kGy ~ 200 kGy electron beam dose. (See Fig. 4(b), Fig. 4(c))

The most pronounced carbon fiber axial pattern change was found at 300 kGy electron beam dose (see Fig. 4(d)). This carbon fiber axial pattern almost disappeared at the 500 kGy electron beam dose (see Fig. 4(f)).

As shown in FIG. 3(c), most of the surface defects of the carbon fiber are removed at the electron beam dose of 200 kGy to 300 kGy, and the internal pores of the carbon fiber are filled.

3(c) and 3(d), the crystal region is re-decomposed at the electron beam dose of 300 kGy to 400 kGy, and internal pores (internal defects) start to occur again.

5 shows the Raman spectrum of the carbon fiber according to the electron beam dose. 5 shows the D band (1360 cm ^-1 ), the G band (1580 cm ^-1 ), and the A band (1520 cm ^-1 ). In FIG. 6 , the area ratio (I _A /I _G ) represents the atypical ratio in the carbon fiber, and the area ratio (I _D /I _G ) represents the defect rate in the carbon fiber.

As shown in Figure 6, the defect rate (I _D /I _G ) increases in the 200 kGy-300 kGy region, so that the tensile strength of the carbon fiber may decrease, but a new bond is formed at the same time as the internal crystals of the carbon fiber are decomposed. The atypical rate (I _A /I _G ) will also increase. The reason why the amorphous ratio (I _A /I _G ) increases is that the internal pores of the carbon fiber are filled by electron beam irradiation. Therefore, even if the defect (I _D /I _G ) increases in the 200kGy-300kGy region, the amorphous rate (I _A /I _G ) also increases at the same time, so the tensile strength of the carbon fiber is rather improved.

As shown in FIG. 7, the tensile strength of carbon fiber (CF2) is higher than the tensile strength (4.08 GPa) of carbon fiber (As-received) before electron beam treatment (4.66 GPa) at the time of treatment with an electron beam dose of 300 kGy (4.66 GPa). It can be seen that the increase is up to 14%.

As shown in FIG. 8, the interfacial shear strength of carbon fiber (CF2) was higher than the interfacial shear strength of carbon fiber (As-received) (50.75 MPa) before electron beam treatment, and the interfacial shear strength (65.17 MPa) during treatment with an electron beam dose of 400 kGy. It can be seen that the increase is up to 28%.

Control unit additional function

The control unit 42 removes the surface defects of the carbon fiber (CF1) (hereinafter, referred to as “step 2-1”), and removes the internal voids of the carbon fiber (CF1) (hereinafter, “step 2-2”). step”), it is possible to find the optimal strength and dose of electron beam, which can remove surface defects and internal voids of carbon fiber (CF2) while relatively reducing or increasing the strength and dose of electron beam. . Here, the intensity of the electron beam is in the range of 0.1 MeV to 5.0 MeV, and the dose of the electron beam is in the range of 50 kGy to 400 kGy.

For example, as shown in Table 1, in step 2-1, the electron beam intensity is increased from 0.1 MeV to 5.0 MeV, and the electron beam dose is decreased from 400 kGy to 50 kGy. In step 2-2, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV, and the electron beam dose is increased from 50 kGy to 400 kGy.

Step 2-1 Step 2-2 electron beam strength Increase from 0.1 MeV to 5.0 MeV 5.0 MeV to 0.1 MeV
reduce to electron beam dose 400kGy to 50kGy
reduce to 50kGy to 400kGy
increase to

As another example, as shown in Table 2, in step 2-1, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV, and the electron beam dose is increased from 50 kGy to 400 kGy. In step 2-2, the electron beam intensity is increased from 0.1 MeV to 5.0 MeV, and the electron beam dose is decreased from 400 kGy to 50 kGy.

Step 2-1 Step 2-2 electron beam strength 5.0 MeV to 0.1 MeV
reduce to Increase from 0.1 MeV to 5.0 MeV electron beam dose 50kGy to 400kGy
increase to 400kGy to 50kGy
reduce to

In this way, the optimum electron beam intensity and electron beam dose, which can eliminate surface defects and internal voids of carbon fiber (CF2), are found. Whether the optimal electron beam intensity and electron beam dose are correct can be found by examining the carbon fiber (CF2) treated with electron beam irradiation with an electron microscope or Raman spectroscopy. Then, by fixing the strength and the electron beam dose to the electron beam intensity and the electron beam dose found in this way, the carbon fiber may be subjected to electron beam irradiation treatment.

delete

delete

The recovery roller 31 winds the carbon fiber (CF2) treated with electron beam irradiation by applying a constant tensile force.

Claims (4)

In order to find the electron beam strength and electron beam dose that can remove both surface defects and internal voids of carbon fiber, step 1-1 to find the electron beam strength and electron beam dose to eliminate surface defects of carbon fiber, and internal voids of carbon fiber A first step consisting of steps 1-2 to find the electron beam intensity and electron beam dose to eliminate
With the electron beam strength and electron beam dose found in the first step, the surface defects and internal voids of the carbon fiber treated with electron beam irradiation were examined by an electron microscope or Raman spectroscopy method, and the electron beam strength and electron beam dose found in the first step were carbon a second step of confirming that the strength of the electron beam and the dose of the electron beam to reduce the surface defects and internal voids of the fiber; and
A third step of irradiating the carbon fiber with the electron beam intensity and the electron beam dose confirmed in the second step,
The electron beam intensity was increased from 0.1MeV to 5.0MeV in step 1-1, the electron beam dose was decreased from 400kGy to 50kGy, and the electron beam intensity was decreased from 5.0MeV to 0.1MeV in step 1-2, and the electron beam dose is increased from 50 kGy to 400 kGy, or
In step 1-1, the electron beam intensity is decreased from 5.0 MeV to 0.1 MeV, the electron beam dose is increased from 50 kGy to 400 kGy, and in the first-2 step, the electron beam intensity is increased from 0.1 MeV to 5.0 MeV, and the electron beam dose is increased. High-strength carbon fiber manufacturing method using electron beam irradiation, characterized in that the reduction from 400 kGy to 50 kGy. delete delete A high-strength carbon fiber manufactured by the method for manufacturing high-strength carbon fiber using the electron beam irradiation of claim 1.

Images