Method for preparing mesophase pitch-based pre-oxidized fiber through electron beam irradiation

Abstract

The invention discloses a method for preparing mesophase pitch-based pre-oxidized fibers through electron beam irradiation. The method comprises the following steps: carrying out hydrogen peroxide spraying treatment on a mesophase pitch fiber sample, then carrying out electron beam irradiation, and alternately repeating for a plurality of times until the fiber reaches a pre-oxidation state. By means of the synergistic oxidation effect of hydrogen peroxide and the efficient cross-linking effect of electron beam irradiation, the cross-linking degree of the fibers is improved under the condition of low irradiation dose, and the pre-oxidation time is remarkably shortened. The method is easy and convenient to operate and low in energy consumption, the obtained pre-oxidized fiber has the good homogenization degree, the production cost of the carbon fiber can be effectively reduced, and the method is suitable for the technical field of pitch-based fiber precursor processing.

Description

Technical Field

[0001] The invention relates to the field of carbon fiber production, and in particular to a method for preparing mesophase asphalt-based pre-oxidized fibers by electron beam irradiation. Background Art

[0002] Asphalt-based carbon fiber is widely used in high-end fields such as aerospace, high-temperature ablation-resistant materials, and high thermal conductivity materials due to its excellent mechanical properties, such as high strength, high modulus, good thermal and electrical conductivity, and extremely low linear expansion coefficient. Generally, the preparation process of asphalt-based carbon fiber includes spinning, pre-oxidation, carbonization, and graphitization. Among them, pre-oxidation is one of the key steps, which determines the final performance of carbon fiber. However, the traditional pre-oxidation process is time-consuming, energy-intensive, and requires a high-temperature environment to promote the oxidative cross-linking of the fiber. This leads to high production costs and easily causes the skin-core effect of the fiber, affecting the homogeneity and final mechanical properties of the carbon fiber.

[0003] In order to shorten the pre-oxidation time and improve production efficiency, researchers have tried to speed up the reaction rate by increasing the oxidation temperature. However, this method often leads to uneven oxidation between the surface and the inside of the fiber, resulting in a distinct skin-core structure, which seriously affects the subsequent processing and performance stability of the fiber. Therefore, it is urgent to develop a new process that can improve the pre-oxidation efficiency while ensuring the homogenization of the fiber.

[0004] In recent years, electron beam irradiation technology has been introduced into carbon fiber preparation as an efficient modification method. Electron beam can quickly trigger the cross-linking reaction of the fiber and introduce more oxygen-containing groups, thereby significantly shortening the thermal oxidation stabilization time. However, the existing electron beam irradiation method still has room for optimization, especially in achieving a balance between uniform fiber oxidation and improving cross-linking efficiency.

[0005] The present invention provides an improved electron beam irradiation process, which combines the synergistic oxidation effect of hydrogen peroxide to achieve efficient pre-oxidation with a low-dose electron beam, significantly shorten the processing time, reduce energy consumption, and obtain uniform and dense mesophase asphalt-based pre-oxidized fibers, providing an efficient and low-cost solution for the large-scale production of asphalt-based carbon fibers. Summary of the invention

[0006] The purpose of the present invention is to provide a method for efficiently preparing mesophase asphalt-based pre-oxidized fibers, which achieves efficient pre-oxidation with a lower irradiation dose through electron beam irradiation technology combined with the synergistic oxidation effect of hydrogen peroxide, significantly shortens the oxidation time, reduces energy consumption, and obtains uniform and dense pre-oxidized fibers, thereby reducing production costs and improving industrial production efficiency.

[0007] To achieve the above object, the present invention proposes a method for preparing mesophase pitch-based pre-oxidized fibers by electron beam irradiation, the specific steps of which include:

[0008] The mesophase pitch fiber sample is placed in a metal tray and installed on an automatic production line. The tray reciprocates along the guide rail. The production line is sequentially equipped with a spray device and an electron beam irradiation device to form a continuous operation process.

[0009] The mesophase pitch fiber samples were treated with hydrogen peroxide spraying at a ratio of 10% to 13% of the fiber mass to increase the oxidation reactivity of the fiber;

[0010] The fiber sample after the spray treatment is irradiated by an electron beam generator, the electron accelerator energy is 10MeV, the irradiation dose rate is 2kGy / s, the scanning uniformity is not less than 98%, and the total irradiation dose is controlled within 1000 to 2000kGy;

[0011] The spraying and irradiation operations are repeated until the fibers reach the desired pre-oxidation state.

[0012] The advantages of the present invention are:

[0013] Efficient pre-oxidation: Electron beam irradiation can quickly induce the cross-linking reaction in the fiber, significantly shorten the pre-oxidation time, and improve the cross-linking degree of the fiber;

[0014] Reduced energy consumption: Compared with the traditional thermal oxidation stabilization process, the present invention achieves efficient oxidation at a lower temperature, reducing energy consumption;

[0015] Homogenized fiber: The synergistic effect of hydrogen peroxide enhances the uniformity of fiber oxidation, avoids the skin-core effect, and ensures the density and consistency of pre-oxidized fiber;

[0016] Simple process: Automatic assembly line operation simplifies the production process, improves production efficiency, and is suitable for large-scale industrial applications.

[0017] The present invention provides a simple and efficient method for preparing mesophase asphalt-based preoxidized fibers, which can be widely used in the field of carbon fibers and their composite materials, and is particularly suitable for the processing and preparation of high-performance thermal conductive and structural materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an overall schematic diagram of the patent of this invention.

[0019] Among them, 1. Liquid storage barrel; 2. Pressure gauge; 3. Valve; 4. Water pump; 5. Liquid supply pipeline; 6. Nozzle; 7. Electron accelerator; 8. Electron beam; 9. Fiber sample; 10. Metal tray; 11. Guide rail. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings, but this should not limit the protection scope of the present invention.

[0021] The present invention utilizes electron beam irradiation to prepare mesophase pitch-based preoxidized fibers. To implement the method of the present invention, an intermittent irradiation device such as Figure 1 As shown, it has the following components:

[0022] - A spraying system capable of spraying hydrogen peroxide, comprising a liquid storage tank 1, a pressure gauge 2, a valve 3, a water pump 4, a liquid supply pipeline 5 and a spray head 6;

[0023] The hydrogen peroxide is controlled by valve 3 to flow from liquid storage barrel 1 along liquid supply pipe 5 into nozzle 6.

[0024] - an electron accelerator 7 capable of emitting an electron beam 8;

[0025] - A metal tray 10 located on the automatic assembly line. A fiber sample 9 is placed in the metal tray 10;

[0026] In addition, the metal tray 10 can be selectively placed on a movable guide rail 11, so that the tray 10 can perform a constant speed reciprocating motion in the automatic assembly line, so that the fiber sample 9 periodically passes through the spray system and the electron beam irradiation system.

[0027] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0028] Embodiments of the present invention include:

[0029] Example 1

[0030] Example 1: Method for preparing mesophase pitch-based pre-oxidized fibers using electron beam irradiation

[0031] Fiber sample preparation

[0032] Place the mesophase pitch fiber precursor (diameter 15-20 μm, mesophase content ≥ 95%, ash content ≤ 70 ppm, softening point 250°C) in a metal tray with a stacking thickness of 500 mm. The sample can be short fiber, long fiber or fabric to ensure that the electron beam energy can fully penetrate the fiber layer.

[0033] Install automatic assembly line

[0034] The metal pallet is placed on the automatic assembly line and moves back and forth along the guide rail. The production line is equipped with a spray device and an electron beam irradiation device. The pallet moves at a constant speed and passes through the spray and irradiation areas in turn to achieve automated processing.

[0035] Hydrogen peroxide spray treatment

[0036] Turn on the spray device and spray hydrogen peroxide on the surface of the fiber sample at a mass ratio of 10% to 13%. The spray system consists of multiple nozzles to ensure that the fiber surface is evenly exposed to hydrogen peroxide, activate the oxidation reaction, and promote fiber pre-oxidation.

[0037] Electron beam irradiation treatment

[0038] The fiber sample after spraying is moved to the electron beam irradiation device. The electron accelerator energy is set to 10MeV, the irradiation dose rate is 2kGy / s, the scanning width is 1000mm, and the scanning uniformity reaches more than 98%. By adjusting the tray moving speed, the total irradiation dose received by the fiber sample is controlled to be 1000-2000kGy.

[0039] Process operation and control

[0040] The tray reciprocates on the guide rail at a preset speed, alternately spraying hydrogen peroxide and irradiating with electron beams until the desired degree of crosslinking is achieved. The total irradiation time is determined by the irradiation dose and the moving speed. The specific parameters can be optimized according to the fiber characteristics and production requirements to achieve a uniform pre-oxidation effect.

[0041] Results and Effects

[0042] The mesophase asphalt-based pre-oxidized fibers treated by this method have a uniform and dense structure, significantly improve the degree of crosslinking, reduce the risk of skin-core effect, and ensure the stability and efficiency of subsequent carbonization and graphitization steps. In addition, compared with the traditional thermal oxidation stabilization process, this method greatly shortens the pre-oxidation time and reduces energy consumption.

[0043] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing mesophase pitch-based preoxidized fibers by electron beam irradiation, characterized in that: The following steps are involved: a) spraying the mesophase pitch fiber sample with hydrogen peroxide; b) subjecting the fiber sample after the spray treatment to electron beam irradiation; c) Repeat steps a) and b) for multiple times to complete the pre-oxidation treatment of the fiber.

2. The method according to claim 1, characterized in that The step a) comprises: A tray is installed on the automatic assembly line, and the mesophase pitch fiber sample is placed in the tray. The tray moves back and forth along the guide rail. A spray device and an electron beam irradiation device are sequentially arranged on the production line.

3. The method according to claim 2, characterized in that The spraying device is used to spray hydrogen peroxide on the surface of the fiber sample at a ratio of 10% to 13% of the mass of the mesophase asphalt fiber.

4. The method according to claim 2, characterized in that: The electron beam irradiation device uses an electron accelerator with an energy of 10 MeV, an irradiation dose rate of 2 kGy / s, a scanning uniformity of not less than 98%, and a scanning width of 1000 mm.

5. The method according to claim 1, characterized in that The total dose of the electron beam irradiation process is 1000 to 2000 kGy, and the dose is controlled by adjusting the irradiation time.

6. The method according to claim 2, characterized in that The tray is made of metal and can reciprocate on the guide rail to perform spraying and irradiation operations.

7. The method according to claim 5, characterized in that Electron beam irradiation can be operated in intermittent or continuous mode to suit different production needs. The mesophase asphalt-based pre-oxidized fiber prepared according to the method described in any one of claims 1 to 7 has the characteristics of high homogenization degree and moderate cross-linking degree, and is suitable for subsequent processing of high-performance carbon fiber.

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