JP6667568B2 - Method for producing oxidized fiber and oxidized fiber - Google Patents

Description

The present invention relates to a technique for pre-oxidizing carbon fibers, and more particularly to a method for producing oxidized fibers that improves the performance of carbon fibers, and an oxidized fiber related thereto.

Carbon fiber is a new carbon material with a carbon content of 90% or more obtained through a series of heat treatments on organic fibers, and has a high specific strength, a high elastic modulus, a high electrical conductivity and a high thermal conductivity, a low thermal expansion coefficient, and a low density. With a series of excellent performances such as high temperature resistance, fatigue resistance, creep resistance, self-lubrication, etc., it is an ideal functional material and structural material, so it is widely used in fields such as aerospace, civil aviation and transportation It is applied and has a wide range of applications.

The production of carbon fiber using polyacrylonitrile (PAN) as a raw yarn includes polymerization, spinning, pre-oxidation and carbonization steps, in which the pre-oxidation step is important for structural changes in the carbon fiber production step. In this stage, the heat treatment process takes the longest time, and it is necessary to convert the linear polymer chains of polyacrylonitrile into heat-resistant oxidized fibers, and to maintain the infusible and non-combustible fibers in the subsequent carbonization step. This is the target process.

In the pre-oxidation process, the structure and performance of the carbon fiber are greatly affected by the structural change of the raw yarn. In industrial production, the pre-oxidation is generally performed by pre-oxidation using the temperature gradient method, and a temperature gradient range suitable for the process is required. If the starting temperature is too low, the pre-oxidation process will not be improved, and it will take a long time and cost. If the starting temperature is too high, a severe exothermic reaction will occur, and the PAN polymer chains having no heat resistance will be cut off. If the end temperature is too high, intensive heat generation will destroy the pre-oxidized fiber structure, excessive pre-oxidation, disadvantageous to the production of high-strength carbon fiber, if the end temperature is too low, Pre-oxidation may be insufficient.

In the pre-oxidation reaction by heating, heat conduction is performed from the outer layer to the inner layer of the yarn with the progress of the pre-oxidation reaction, so that an oxide layer (film) having a precise ladder structure is formed on the outer layer of the yarn, and this is formed. 1 prevents the oxygen from diffusing into the core in the inner layer of the yarn, but as shown in FIG. 1, the oxidized oxide layer 111 (coating) and the non-oxidized core 112 in the single fiber 11 of the oxidized fiber 10. Has a significantly different skin-core structure, a skin-core intervening surface 113 between the oxide layer 111 and the core 112, and the measurement of the skin-core structure is performed by a scanning electron microscope (SEM, A solid body image is taken with a scanning electron microscope, the cross section of the oxidized fiber is observed, and the cross sectional area of the oxidized layer, the cross sectional area of the core, and the cross sectional area of the oxidized fiber are calculated. However, the core ratio (%) obtained by observing the appearance of the skin / core structure is obtained by dividing the core cross-sectional area by the sum of the oxide layer cross-sectional area and the core cross-sectional area, that is, the core ratio (%). ) Is the core cross-sectional area divided by the oxidized fiber cross-sectional area, and the physical properties of the oxidized fiber 10 and the manufactured carbon fiber, such as tensile strength and tensile modulus, are It is determined by the degree of oxidation and the degree of cyclization of the fiber 10 or the oxide layer 111. The higher the degree of oxidation and the degree of cyclization of the oxide fiber 10 or the oxide layer 111, the higher the tensile strength and the strength of the carbon fiber produced by the oxide fiber 10. The tensile modulus increases. Since the oxidized layer 111 is in an oxidized state, it has a precise structure and a high tensile strength and a high tensile modulus of the manufactured carbon fiber, and the core 112 is in an incompletely oxidized state or is not oxidized. Such a skin, which has a loose structure and has low tensile strength and low tensile elasticity of the manufactured carbon fiber, is caused by inconsistency in the degree of oxidation of the oxide layer 111 and the core 112. -The core structure is one of the factors that reduce the tensile strength of carbon fiber, so in the pre-oxidation reaction process, how to shorten the pre-oxidation time, improve the pre-oxidation degree, and further improve the skin Eliminating the core structure has sufficient and important significance in reducing the production cost of carbon fiber and improving its performance (tensile strength and tensile modulus).

In view of this, the present invention provides an oxidized fiber that effectively shortens the oxidation time of the oxidized fiber, effectively reduces the skin-core structure of the oxidized fiber, or prevents the oxidized fiber from having a remarkable skin-core structure. It is an object of the present invention to provide a method for producing the same and an oxidized fiber relating to the method.

The present invention applies to pre-oxidizing a fiber bundle into an oxidized fiber bundle, collecting and bundling a single fiber or a plurality of the fibers, wherein the oxidized fiber bundle is formed by converting a single oxidized fiber or a plurality of the oxidized fibers. Collect and bundle, as follows:
Yarn supply procedure: preparing the fiber bundle;
Microwave treatment procedure: A method for producing an oxidized fiber, comprising a step of exposing the fiber bundle under microwave conditions to form the oxidized fiber bundle.

The present invention, in one embodiment, is applied to pre-oxidize the fiber bundle to the oxidized fiber bundle, wherein the fiber bundle comprises a single fiber or a plurality of the fibers collected and bundled, the oxidized fiber bundle comprising: A single oxidized fiber or a plurality of such oxidized fibers are collected and bundled, as follows:
a. Arrangement of transmission unit and microwave processing unit,
b. Feeding the fiber bundle: setting the fiber bundle in the transmission unit, where the transmission unit passes the fiber bundle through the microwave processing unit;
c. Starting up the microwave processing unit: controlling the microwave conditions with the microwave processing unit;
d. Commissioning the transmission unit: treating the fiber bundle in the transmission unit under microwave conditions for a continuous time to turn the fiber bundle into the oxidized fiber bundle;
A method for producing an oxidized fiber, comprising the steps of:

The method for producing an oxidized fiber, wherein the fiber of the fiber bundle is provided so as to be pre-oxidized to the oxidized fiber in the method for producing an oxidized fiber.

The microwave conditions are a microwave frequency of 300 to 300,000 MHz, a microwave output of 1 to 1000 kW / m ² , a working temperature of 100 to 600 ° C., and any one of oxygen, air, and ozone or a mixture thereof. A method for producing the oxidized fiber, comprising an atmosphere gas.

The method for producing the oxidized fiber, wherein the treatment time is 1 to 40 minutes.

The method for producing the oxidized fiber, wherein the microwave output is 10 to 24 kW / m ² .

A method for producing the oxidized fiber, wherein the frequency of the microwave is 2000 to 3000 MHz, the working temperature is 150 to 350 ° C, and the processing time is 5 to 20 minutes.

The method for producing an oxidized fiber, wherein the fiber bundle is any one of polyacrylonitrile (PAN) fiber, bituminous fiber, and other organic fibers.

The transmission unit includes a supply device for supplying the fiber bundle, a winding device for pulling the fiber bundle, and continuously feeding the fiber bundle through a heating furnace, and the microwave processing unit includes: The oxidized fiber, comprising: a heating furnace provided with a magnetron for generating a microwave frequency and the microwave output; and an air supply device for supplying the atmosphere gas to the heating furnace. Manufacturing method.

The method for producing the oxidized fiber, wherein the magnetron and the air supply device are electrically connected to a control unit.

A method for producing the oxidized fiber, wherein a heat retaining unit is provided inside the heating furnace.

The method for producing an oxidized fiber, wherein the heat retaining unit may be any one of a metal oxide, a carbide, a microwave highly reactive material, or a combination thereof.

The method for producing the oxidized fiber, wherein the fiber bundle is provided so as to be continuously irradiated with the irradiation from the microwave processing unit in a lap winding in the heating furnace.

The present invention is an oxidized fiber comprising at least an oxidized layer and a core, wherein the oxidized layer covers the outside of the core, and the cross-sectional area of the oxidized layer is at least that of the oxidized fiber. The oxidized fiber is formed by exposing the fiber under the microwave condition, and the oxidized fiber is formed by exposing the organic fiber to the microwave. It is characterized by being exposed and manufactured under conditions.

The cross-sectional area of the oxide layer is provided so as to occupy at least 60% or more of the cross-sectional area of the oxidized fiber.

The cross-sectional area of the oxide layer is provided so as to occupy at least 80% of the cross-sectional area of the oxidized fiber.

The cross-sectional area of the oxide layer is provided so as to occupy at least 90% of the cross-sectional area of the oxidized fiber.

The cross-sectional area of the oxide layer is provided so as to occupy at least 99% or more of the cross-sectional area of the oxidized fiber.

The manufacturing method of the oxidized fiber disclosed in the present invention is to perform ultra-high-speed pre-oxidation treatment on the fiber bundle with the focused microwave of the microwave processing unit, process the fiber bundle into the oxidized fiber, and oxidize the oxidized fiber. At the same time that the oxide layer in the oxidized fiber occupies at least 50% or more of the cross-sectional area of the oxidized fiber, thereby effectively reducing the skin core structure of the oxidized fiber. In the present invention, when the oxidized layer in the fiber occupies at least 80% or more of the cross-sectional area of the oxidized fiber or because the oxidized fiber does not have a remarkable skin-core structure, As a more aggressive and reliable means, the performance of carbon fibers can be improved.

Image of conventional oxidized fiber skin / core structure. 1 is a basic flowchart relating to a method for producing an oxidized fiber of the present invention. 5 is a structural image of a transmission unit and a microwave processing unit in the method for manufacturing an oxidized fiber of the present invention. The fiber bundle, the oxide fibers by each ^{12kW / m 2, 16kW / m} 2, 20kW / m 2, 24kW / focusing ^{m 2} microwaving and従來heating method by the manufacturing method of the oxide fibers of the present invention Oxidation degree curve diagram. The degree of cyclization of the oxidized fiber obtained by subjecting the fiber bundle to a focused microwave treatment of 24 kW / m ² by the method for producing an oxidized fiber of the present invention for 2 minutes, 4 minutes, 5 minutes, 10 minutes, and 15 minutes Curve diagram. The substantial image of the cross section of the oxidized fiber in the oxidized fiber obtained by subjecting the fiber bundle to the focused microwave treatment of 24 kW / m ² by the method for producing the oxidized fiber of the present invention for 5 minutes. The substantial image of the cross section of the oxidized fiber in the oxidized fiber obtained by subjecting the fiber bundle to the focused microwave treatment of 24 kW / m ² by the method for producing the oxidized fiber of the present invention for 10 minutes. The substantial image of the cross section of the oxidized fiber in the oxidized fiber obtained by subjecting the fiber bundle to the focused microwave treatment of 24 kW / m ² by the method for producing the oxidized fiber of the present invention for 15 minutes. 6 is another flowchart relating to the method for producing oxidized fiber of the present invention. The structural image of the heating furnace by the manufacturing method of the oxidation fiber of this invention. 2 is a structural image of the oxidized fiber of the present invention.

The present invention provides an oxidized fiber that effectively shortens the oxidation time of the oxidized fiber, effectively reduces the skin-core structure of the oxidized fiber, or prevents the oxidized fiber from having a remarkable skin-core structure. The method for producing oxidized fiber according to the present invention includes the following procedure as shown in FIGS. 2 and 3.

a. Arrangement of the transmission unit 30 and the microwave processing unit 40. In operation, the transmission unit 30 includes a supply device 31 for supplying the fiber bundle 20, and a winding device 32 for pulling the fiber bundle 20 and continuously feeding the fiber bundle 20 through the heating furnace 33. The fiber bundle 20 is formed by collecting and bundling a single fiber (not shown) or a plurality of the fibers, and the microwave processing unit 40 includes at least one fiber for generating the microwave in the heating furnace 33. An air supply device 42 for supplying oxygen-containing air to the magnetron 41 and the heating furnace 33 is provided. The air supply device 42 is connected to the air supply port 331 of the heating furnace 33 and Air is to be sent into the heating furnace 33 from the air supply port 331 and discharged from the exhaust port 332 of the heating furnace 33, and the transmission unit 30 is further inserted into the heating furnace 33. A heat insulation unit 34 is provided, In the microwave processing unit 40, a plurality of the magnetrons 41 are provided in the heating furnace 33, and the plurality of the magnetrons 41 are disposed on the upper and lower sides of the heating furnace 33 so as to face each other or to be shifted in relative position, or The magnetrons 41 shown in FIG. 3 are arranged on the side (upper or lower side) of the heating furnace 33, and are vertically opposed to each other on the upper and lower sides of the heating furnace 33. As shown in FIG. The magnetrons 41 are vertically opposed to each other. Thus, the upper half and the lower half of the fiber bundle 20 passing through the heating furnace 33 are simultaneously and uniformly subjected to the microwave irradiation processing. Since the length of the heating furnace 33 can be shortened, the manufacturing time is reduced, and the manufacturing speed is increased.

b. Supply of the fiber bundle 20: setting the fiber bundle 20 in the transmission unit 30 and causing the fiber bundle 20 to pass through the microwave processing unit 40 at the transmission unit 30, for example, wound The fiber bundle 20 is set in the transmission unit 30 for sending the fiber bundle 20 continuously through the working area of the microwave processing unit 40 by the transmission unit 30, and in the embodiment, the fiber bundle being wound is set. 20 is set in the supply device 31, the tip of the fiber bundle 20 is passed through the heating furnace 33, and is fixed to the winding device 32. The fiber bundle 20 is made of polyacrylonitrile. (PAN), bituminous fiber or any one of other organic fibers.

c. Start-up of the microwave processing unit 40: controlling microwave conditions in the microwave processing unit 40. The microwave conditions are a microwave frequency of 300 to 300,000 MHz, a microwave output of 1 to 1000 kW / m ² , a working temperature of 100 to 600 ° C., and any one of oxygen, air, and ozone or a mixture thereof. Atmospheric gas is included, and the atmospheric gas is the oxygen-containing air described above. In this embodiment, the oxygen-containing air is simultaneously supplied from the air supply device 42 into the heating furnace 33.

d. Start-up of the transmission unit 30: the transmission unit 30 feeds the fiber bundle 20 and processes the fiber bundle 20 continuously according to the microwave conditions, so that the fiber bundle 20 is turned into the oxidized fiber bundle 20A. For example, in the transmission unit 30, the fiber bundle 20 is passed through the working area of the microwave processing unit 40, and the bundled microwave processing is continuously performed for 1 to 40 minutes to form the oxidized fiber bundle 20A. The processing time is set to 1 to 40 minutes. In the present embodiment, the fiber bundle 20 is passed through the heating furnace 33 by the transmission unit 30, and the focused microwave by the microwave processing unit 40 is used. The treatment is carried out continuously for 1 to 40 minutes to provide the oxidized fiber bundle 20A. In addition, the fiber bundle 20 is passed through the heating furnace 33 by lap winding, and And said The microwave processing unit 40 continuously performs the focusing microwave processing for 1 to 40 minutes to provide the oxidized fiber bundle 20A. For example, the fiber bundle 20 enters from the front of the heating furnace 33, and After passing through the inside of the heating furnace 33, it is sent to the rear part of the heating furnace 33, further from the rear part of the heating furnace 33 to the front part of the heating furnace 33, and again, the front part of the heating furnace 33. Is to be sent to the heating furnace 33, and the oxidized fiber bundle 20A satisfying the requirements is supplied from the rear part of the heating furnace 33 by repeating such overlapping winding. In the lap winding method, the required length of the heating furnace 33 can be effectively reduced.

In the manufacturing method of the oxidized fiber of the present invention, by operating the transmission unit 30, the fiber bundle 20 is sent at a preset speed so as to pass through the work area of the microwave processing unit 40, and the fiber bundle 20 is moved. When passing through the working area of the microwave processing unit 40, the fiber bundle 20 continuously passing through the heating furnace 33 is subjected to an ultra-high-speed pre-oxidation treatment by using a focused microwave, The fiber bundle 20 is provided to be processed into the oxidized fiber bundle 20A, and the fiber bundle 20 is formed by collecting and bundling the fiber or a plurality of the fibers, and the oxidized fiber bundle 20A is formed by the oxidized fiber 21 or A plurality of the oxidized fibers 21 are collected and bundled, and the fibers of the fiber bundle 20 are provided so as to be pre-oxidized to the oxidized fibers 21 by the method of manufacturing the oxidized fibers.

As shown in FIG. 4, the method for producing oxidation fiber of the present invention, with respect to the fiber bundle 20, without each microwave, microwave power 12 kW / ^{m 2,} microwave power 16 kW / ^{m 2,} microwave power 20kW / ^{m 2,} and subjected to focused microwave treatment microwave output 24 kW / ^{m 2,} therein, the applied microwave power 24 kW / ^{m 2} of a focused microwave treatment for 10 minutes with respect to the fiber bundle 20, The oxidation degree of the oxidized fiber 21 of the oxidized fiber bundle 20A reaches 100%, and the oxidized fiber bundle 20A is obtained by collecting and bundling the single oxidized fiber 21 or a plurality of the oxidized fibers 21; relative to the fiber bundles 20, when applied microwave power 20 kW / ^{m 2} of a focused microwave treatment for 15 minutes, the degree of oxidation of the oxidized fibers 21 of oxide fiber bundle 20A is also 100% And, with respect to the fiber bundle 20, when subjected to focused microwave treatment microwave output 16 kW / ^{m 2} 25 min, degree of oxidation of the oxidized fibers 21 of oxide fiber bundle 20A reaches 100%, the fiber bundle 20 is subjected to a focusing microwave treatment with a microwave output of 12 kW / m ² for 40 minutes, and the degree of oxidation of the oxidized fiber 21 in the oxidized fiber bundle 20A does not reach 100%. The degree of oxidation of the oxidized fiber 21 reaches 89%. In a conventional heating step, the degree of oxidation of the oxidized fiber 21 is at most 40 minutes after heating the fiber bundle 20 at 270 ° C. without a microwave. Compared with the microwave manufacturing method of the present invention and the conventional heating manufacturing process, the present invention effectively increases the degree of oxidation of the oxidized fibers 21 and effectively reduces the manufacturing time. Shorten In particular, when the fiber bundle 20 is subjected to a focused microwave treatment with a microwave output of 24 kW / m ² for 10 minutes, the oxidation fiber 21 reaches an oxidation degree of 100%. Under the optimum manufacturing conditions.

As shown in FIG. 5, the fiber bundle 20 was subjected to focused microwave treatment with a microwave output of 24 kW / m ² for 2 minutes, 4 minutes, 5 minutes, 10 minutes, and 15 minutes. The degree of cyclization of the oxidized fiber 21 can be seen. Among them, the degree of cyclization of the oxidized fiber 21 reaches 100% in 5 minutes. The time required for the degree of oxidation is less than 10 minutes. As shown in FIGS. 6 to 8, the bundle 20 is subjected to a focusing microwave treatment of 24 kW / m ² for 5 minutes, 10 minutes, and 15 minutes, and the oxidized fiber bundle 20A obtained is oxidized. FIG. 4 is a substantial image of a cross section of the fiber 21 taken by a scanning electron microscope (SEM), in which the oxide layer 211 is 99.0% or more of the oxide fiber 21 or the cross-sectional area of the oxide layer 211. Occupies 99.0% or more of the cross-sectional area of the oxidized fiber 21, and it is found that there is no noticeable skin-core structure.

As shown in Tables 1 and 2, Table 1 shows the fiber bundle 20 measured and measured in the conventional manufacturing process using an electric heating tube and the microwave manufacturing process which is the method for manufacturing the oxidized fiber of the present invention. Is a comparison table of the tensile strength of the oxidized fiber bundle 20A and the carbon fiber bundle obtained by subsequent carbonization, and Table 2 shows a conventional manufacturing process using an electric heating tube and a microwave according to the manufacturing method of the present invention. 7 is a comparison table of tensile modulus of the fiber bundle 20, the oxidized fiber bundle 20A, and the carbon fiber bundle obtained by subsequent carbonization, which were measured in the manufacturing process of FIG. The above-mentioned conventional heating of an electric heating tube is performed under the conditions of a heating furnace temperature of 270 ° C. and a processing time of 40 minutes. The physical properties thus obtained are shown in Comparative Example 1 and the oxidized fiber of the present invention described above. The microwave manufacturing process, which is a manufacturing method of the above, is performed under the following manufacturing conditions: a temperature of the heating furnace of 220 ° C., a microwave frequency of 2450 MHz, a microwave output of 24 kW / m ² , and a processing time of 10 minutes. The physical properties are shown in Example 1, where the fiber bundles 20 of Comparative Example 1 and Example 1 were made of polyacrylonitrile.

表１に示す実施例１における本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれ、得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は、比較例１の１．３倍（３６７５を２８２４で割った結果により）、即ち引張強度が３０％向上し、マイクロ波の製造工程では、ＰＡＮ酸化を更に完全にすることができるから、マイクロ波の製造工程による該酸化繊維束の引張強度が従來の電熱管加熱の製造工程による該酸化繊維束の引張強度よりやや低く、これが、本発明のマイクロ波の製造工程で、該繊維束の酸化程度を更に向上するもう一つの証拠でもある。

Tensile strength of the oxidized fiber bundle obtained in the microwave manufacturing process, which is the method for manufacturing the oxidized fiber of the present invention in Example 1 shown in Table 1, and finally the carbon fiber bundle obtained by carbonizing it Is 1.3 times that of Comparative Example 1 (based on the result of dividing 3675 by 2824), that is, the tensile strength is improved by 30%, and the PAN oxidation can be further completed in the microwave manufacturing process. The tensile strength of the oxidized fiber bundle in the wave manufacturing process is slightly lower than the tensile strength of the oxidized fiber bundle in the conventional heating tube heating manufacturing process, and this is the microwave manufacturing process of the present invention. It is another evidence that the degree of oxidation is further improved.

表２に示す実施例１の本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれ、得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張弾性率は、比較例１の１．１７倍（２２７．１を１９４．４で割った結果により）、即ち引張弾性率が１７％向上する。

Tensile elasticity of the oxidized fiber bundle obtained in the microwave manufacturing process which is the method of manufacturing the oxidized fiber of the present invention of Example 1 shown in Table 2 and finally obtained by carbonizing the oxidized fiber bundle The modulus is 1.17 times that of Comparative Example 1 (from the result of dividing 227.1 by 194.4), that is, the tensile modulus is improved by 17%.

Comparing the oxidized fiber bundle of the fiber bundle according to the present invention and the conventional heating step, the present invention can reduce the time required for the conventional heating step by 40 minutes to 10 minutes, thereby improving the production efficiency by three times. In the present invention, the production time is shortened, the tensile strength of the carbon fiber bundle is improved by 30% and the tensile elastic modulus is improved by 17% with respect to the conventional heating step. Since the cross-sectional area of the oxidized layer 211 in the oxidized fiber 21 of the oxidized fiber bundle 20A occupies 99.0% or more of the cross-sectional area of the oxidized fiber 21, there is no remarkable skin-core structure, Since the cross section of the fiber bundle 20A is approaching uniform, the tensile strength and the tensile modulus of the carbon fiber bundle are improved. Performance can be improved.

In a preferred embodiment of the method for producing an oxidized fiber of the present invention, the fiber bundle is subjected to a focused microwave treatment of 24 kW / m ² for 5 to 10 minutes at the time of implementation. Can be subjected to a focusing microwave treatment of 24 kW / m ² for 5 to 10 minutes by the manufacturing method described in FIG. 3. As shown in FIG. And a winding device 32 for pulling the fiber bundle 20 and continuously feeding it through a heating furnace 33. The microwave processing unit 40 includes the heating furnace 33 The magnetron 41 for generating microwaves and an air supply device 42 for supplying oxygen-containing air to the heating furnace 33 are provided. After passing through the heating furnace 33, A continuous manufacturing method in which a carbon fiber bundle is produced by subsequent carbonization instead of winding by the winding device 32, or the wound fiber bundle 20 is unwound by the supply device 31, and the winding device 32 The method is applied to a manufacturing method of winding by using

Of course, the method for producing oxidized fibers of the present invention is also applied to a batch production method, and an embodiment of the batch production method is performed in the following procedure. For example, as shown in FIG. Is applied to pre-oxidize the fiber bundle 20 into the oxidized fiber bundle 20A.

Yarn supply procedure S01: preparing the fiber bundle 20, the fiber bundle 20 is made by collecting and bundling a single fiber or a plurality of the fibers, and the fiber bundle 20 is made of polyacrylonitrile (PAN) fiber, bituminous fiber or other Any one of the organic fibers may be used.

Microwave treatment procedure S02: The fiber bundle 20 is exposed under the microwave condition, the microwave condition being a microwave frequency of 300 to 300,000 MHz, a microwave output of 1 to 1000 kW / m2, and a working temperature of 100 to 600. ℃, and an atmosphere gas which is any one of oxygen, air and ozone or a mixture thereof.

In the manufacturing method of the oxidized fiber of the present invention, in the embodiment in which the microwave processing unit 40 is provided with the air supply device 42 that supplies oxygen-containing air to the heating furnace 33, The oxygen-containing air sent to 33 may be any one of oxygen, air, ozone, or a mixture thereof.

The transmission unit 30 in the oxidized fiber manufacturing method of the present invention includes a supply device 31 for supplying the fiber bundle 20, and a winding device for pulling the fiber bundle 20 and continuously feeding the fiber bundle 20 through the heating furnace 33. The microwave processing unit 40 is provided with the magnetron 41 that generates the microwave to the heating furnace 33, and the air supply device 42 for supplying oxygen-containing air to the heating furnace 33. The winding device 32, the magnetron 41, and the air supply device 42 are electrically connected to a control unit 50, and the control unit 50 controls the winding device 32, the magnetron 41, and the air supply device. Controls the operation of the air blower 42 and, depending on the characteristics of the fiber bundle 20 to be processed or the product specifications, the number of revolutions of the winder 32, the output of the magnetron 41 and the air blower The operating parameters, such as 42 of the flow rate can be set.

The transmission unit 30 in the oxidized fiber manufacturing method of the present invention includes the supply device 31 that supplies the fiber bundle 20, the winding device for pulling the fiber bundle 20, and continuously feeding the fiber bundle 20 through the heating furnace 33. The heating unit 33 is provided in the heating furnace 33, and the heat retaining unit 34 is disposed in the heating furnace 33. As shown in FIG. As shown in FIG. 10, a plurality of the fiber bundles 20 are arranged in parallel with each other and supplied to the heating furnace 33 by the supply device 31. Is supposed to be.

When the method for producing oxidized fiber of the present invention is carried out, as shown in FIG. 3, the transmission unit 30 includes a heating unit 33 inside the heating furnace 33, and a heating unit 34 disposed at a vertical position of the fiber bundle 20 feeding path. Alternatively, as shown in FIG. 10, the heat retaining unit 34 surrounding the fiber bundle 20 feeding path is disposed inside the heating furnace 33, whereby the fiber bundle 20 is provided so as to receive heat uniformly.

In each of the above-described embodiments of the present invention, the heat retaining unit 34 may be made of any one of a metal oxide, a carbide, and a microwave highly reactive material, or a combination thereof.

In the manufacturing method of the oxidized fiber of the present invention, at the time of execution, as shown in FIG. 3, the microwave processing unit 40 has the magnetron 41 disposed at the upper and lower positions of the fiber bundle 20 feeding path, respectively. A plurality of the magnetrons 41 surrounding the path are arranged, so that the fiber bundle 20 is provided so as to perform the focused microwave processing uniformly.

FIG. 4 shows that, as described above, when the fiber bundle 20 is subjected to a focused microwave treatment with a microwave output of 12 kW / m ² at 220 ° C. for 40 minutes, the degree of oxidation of the oxidized fiber 21 is reduced. In the conventional heating step, the degree of oxidation of the oxidized fibers 21 reaches 70% 40 minutes after heating the fiber bundle 20 at 270 ° C. without microwaves. Therefore, in the method for producing oxidized fiber of the present invention, the degree of oxidation can be increased at a relatively low temperature with respect to the conventional heating step, so that heat energy consumption can be reduced.

As shown in Table 3, Table 3 shows that the fiber bundle 20 and the oxidized fiber were measured in the conventional manufacturing process by heating the electric heating tube and in the microwave manufacturing process, which is the method for manufacturing the oxidized fiber of the present invention. It is a comparison table of the tensile strength of the fiber bundle 20A and the carbon fiber bundle obtained by subsequent carbonization. The above-mentioned conventional heating of an electric heating tube is performed at a temperature of 270 ° C. in the heating furnace and a processing time of 40 minutes as production conditions. The physical properties obtained thereby are shown in Comparative Example 1, and the microwave manufacturing process, which is the above-described method for manufacturing an oxidized fiber of the present invention, is performed under the following conditions: The processing was performed at a frequency of 2450 MHz and a processing time of 40 minutes. The physical properties obtained at a microwave output of 22 kW / m ² were obtained in Example 2, and the physical properties obtained at a microwave output of 20 kW / m ² were obtained in Example 3. ,micro Output 16 kW / physical properties obtained in m ² Example 4, the physical properties obtained in microwave power 15 kW / m ² is shown in Example 5, the fiber of Comparative Example 1 and all examples The bundle 20 is made of polyacrylonitrile, and the cross section of the oxidized fiber 21 of the oxidized fiber bundle 20A in the comparative example 1 and each example is substantialized by a scanning electron microscope (SEM, Scanning Electron Microscope). As calculated by taking an image, the sectional area of the oxidized layer 211 is divided by the sectional area of the oxidized fiber 21, that is, the ratio of the oxidized layer 211 to the oxidized fiber 21 is shown in Table 3.

表３に示すように、実施例５では、本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれて得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は比較例１の１．１３倍、即ち、引張強度が１３％向上し、該酸化層２１１の断面積を該酸化繊維２１の断面積で割って５１．２％となり、即ち該酸化層２１１が該酸化繊維２１の５１．２％を占め、実施例４では、本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれて得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は比較例１の１．１７倍、即ち引張強度が１７％向上し、該酸化層２１１の断面積を該酸化繊維２１の断面積で割って６１．５％となり、即ち該酸化層２１１が該酸化繊維２１の６１．５％を占め、実施例３では、本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれて得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は比較例１の１．２３倍、即ち引張強度が２３％向上し、該酸化層２１１の断面積を該酸化繊維２１の断面積で割って８２．７％となり、即ち該酸化層２１１が該酸化繊維２１の８２．７％を占め、実施例２では、本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれて得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は比較例１の１．２７倍、即ち引張強度が２７％向上し、該酸化層２１１の断面積を該酸化繊維２１の断面積で割って９１．３％となり、即ち該酸化層２１１が該酸化繊維２１の９１．３％を占め、実施例１では、本発明の酸化繊維の製造方法であるマイクロ波の製造工程で行なわれて得られた酸化繊維束、最後にそれを炭素化して得られた炭素繊維束の引張強度は比較例１の１．３倍、即ち引張強度が３０％向上し、該酸化層２１１の断面積を該酸化繊維２１の断面積で割って９９．０％となり、即ち該酸化層２１１が該酸化繊維２１の９９．０％を占める。

As shown in Table 3, in Example 5, the oxidized fiber bundle obtained by performing the microwave manufacturing process as the oxidized fiber manufacturing method of the present invention, and finally the carbon fiber obtained by carbonizing the oxidized fiber bundle The tensile strength of the bundle is 1.13 times that of Comparative Example 1, that is, the tensile strength is improved by 13%, and the cross-sectional area of the oxide layer 211 is divided by the cross-sectional area of the oxidized fiber 21 to be 51.2%. The oxidized layer 211 occupies 51.2% of the oxidized fiber 21. In Example 4, the oxidized fiber bundle obtained by performing the microwave manufacturing process of the oxidized fiber manufacturing method of the present invention, and finally the The carbon fiber bundle obtained by carbonizing the carbon fiber bundle has a tensile strength 1.17 times that of Comparative Example 1, that is, the tensile strength is improved by 17%, and the sectional area of the oxide layer 211 is divided by the sectional area of the oxide fiber 21. 61.5%, that is, the oxidized layer 211 makes 61.5% of the oxidized fiber 21. Therefore, in Example 3, the tensile strength of the oxidized fiber bundle obtained by performing the microwave manufacturing process of the oxidized fiber manufacturing method of the present invention, and finally the carbon fiber bundle obtained by carbonizing the oxidized fiber bundle was 1.23 times that of Comparative Example 1, that is, the tensile strength is improved by 23%, and the sectional area of the oxidized layer 211 is divided by the sectional area of the oxidized fiber 21 to be 82.7%. In the second embodiment, the oxidized fiber bundle obtained by performing the microwave manufacturing process, which is the method for manufacturing the oxidized fiber according to the present invention, is finally carbonized. The tensile strength of the carbon fiber bundle thus obtained is 1.27 times that of Comparative Example 1, that is, the tensile strength is improved by 27%, and the sectional area of the oxide layer 211 is divided by the sectional area of the oxide fiber 21 to be 91.3%. That is, the oxidized layer 211 occupies 91.3% of the oxidized fiber 21, and Is the tensile strength of the oxidized fiber bundle obtained by performing the microwave manufacturing process of the oxidized fiber production method of the present invention, and finally, the carbon fiber bundle obtained by carbonizing it. 0.3 times, that is, the tensile strength is improved by 30%, and the sectional area of the oxidized layer 211 is divided by the sectional area of the oxidized fiber 21 to be 99.0%. Occupies 0%.

The oxidized fiber 21 according to the present invention includes the oxidized layer 211 and a core 212, and the oxidized layer 211 is provided so as to cover the outside of the core 212. , 50% or more of the oxidized fibers 21 or the cross-sectional area of the oxidized layer 211 occupies at least 50% or more of the oxidized fiber 21, and as shown in FIG. 80% or more of the fiber 21 or the cross-sectional area of the oxide layer 211 occupies at least 80% of the cross-sectional area of the oxidized fiber 21.

Needless to say, the oxidized fiber 21 posted in the present invention is formed by forming the fiber bundle 20 by any one of the above-described oxidized fiber manufacturing methods which can be performed by the present invention, and the oxidized layer 211 is formed by the micro layer. Since the oxide layer 211 is formed under the wave condition, the oxide layer 211 is a microwave oxide layer, and the oxide layer 211 of the oxide fiber 21 of the oxide fiber bundle 20A is at least 50% or more of the oxide fiber 21. Occupy.

In operation, the fiber bundle 20 may be any one of polyacrylonitrile (PAN), bitumen or other organic fibers. Of course, the oxidized fiber is irradiated with microwaves of 24 kW / m ² and subjected to a focusing microwave treatment on the fiber bundle 20 for 10 minutes, and then the oxidized layer 211 of the oxidized fiber 21 of the oxidized fiber bundle 20A is removed. 99.0% of the oxidized fibers 21 or the cross-sectional area of the oxidized layer 211 occupies 99.0% of the cross-sectional area of the oxidized fibers 21.

According to the method for producing oxidized fiber disclosed in the present invention, the fiber bundle is subjected to ultra-high-speed pre-oxidation treatment using a focused microwave by a microwave processing unit to process the fiber bundle into an oxidized fiber bundle. By doing so, the oxidation time of the oxidized fiber bundle can be effectively shortened, and at the same time, the oxidized layer of the oxidized fiber bundle subjected to the oxidation treatment by the focused microwave has at least a cross-sectional area of at least 50%. % Or more, it is a relatively more aggressive and reliable means provided to effectively reduce the skin-core structure of the oxidized fiber and to prevent the oxidized fiber from having a pronounced skin-core structure. As a result, the performance of the carbon fiber can be improved.

The embodiments described above are only used to explain the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement it based on it. Therefore, the patent scope of the present invention should not be limited thereby, and even if they are changed or modified based on the concept described in the present invention, they are all included in the claims of the present invention. Shall be.

DESCRIPTION OF SYMBOLS 10 Oxidized fiber 11 Fiber 111 Oxidized layer 112 Core part 113 Skin core interface 20 Fiber bundle 20A Oxidized fiber bundle 21 Oxidized fiber 211 Oxidized layer 212 Core part 30 Transmission unit 31 Feeding device 32 Winding device 33 Heating furnace 331 Air supply port 332 Exhaust port 34 Heat insulation unit 40 Microwave processing unit 41 Magnetron 42 Air supply device 50 Control unit S01 Yarn supply procedure S02 Microwave processing procedure

Claims (12)

A method for producing oxidized fibers used for pre-oxidizing a fiber bundle (20) into an oxidized fiber bundle (20A),
The fiber bundle (20) is made by collecting and bundling a single fiber or a plurality of fibers,
The oxidized fiber bundle (20A) is formed by collecting and bundling a single oxidized fiber (21) or a plurality of the oxidized fibers (21),
The method for producing the oxidized fiber is as follows:
Yarn supply procedure (S01): preparing the fiber bundle (20);
Microwave treatment procedure (S02): exposing the fiber bundle (20) under microwave conditions to form the oxidized fiber bundle (20A);
Procedure is included,
The fiber bundle (20) is continuously irradiated by the microwave processing unit (40) while passing through the heating furnace (33) by repeating lap winding,
In the repetition of the lap winding, the fiber bundle (20) enters the heating furnace (33) from the front of the heating furnace (33) and is sent to the rear of the heating furnace (33). The fiber bundle (20) is sent from the rear part of the heating furnace (33) to the front part of the heating furnace (33), and again, the fiber bundle (20) is sent from the front part of the heating furnace (33). Sent to the rear of the heating furnace (33) ,
The microwave conditions include a microwave frequency of 300 to 300,000 MHz, a microwave output of 1 to 1000 kW / m ² , a working temperature of 100 to 600 ° C., a processing time of 1 to 40 minutes, and any one of oxygen, air, and ozone. Characterized in that it contains an ambient gas which is one or a mixture thereof ,
A method for producing oxidized fibers. The microwave power is 10 to 24 kW / m ² ,
A method for producing an oxidized fiber according to claim 1 . The microwave frequency is 2000-3000 MHz, the working temperature is 150-350 ° C., and the processing time is 5-20 minutes,
A method for producing an oxidized fiber according to claim 1 . The fiber bundle (20) may be any one of polyacrylonitrile (PAN) fiber, bitumen fiber, and other organic fibers.
A method for producing an oxidized fiber according to claim 1. A method for producing an oxidized fiber used for pre-oxidizing a fiber bundle (20) into an oxidized fiber bundle (20A),
The fiber bundle (20) is formed by collecting and bundling a single fiber or a plurality of fibers,
The oxidized fiber bundle (20A) is formed by collecting and bundling a single oxidized fiber (21) or a plurality of the oxidized fibers (21),
The method for producing the oxidized fiber is as follows:
a. Arrangement of the transmission unit (30) and the microwave processing unit (40),
b. Supply of the fiber bundle (20): The fiber bundle (20) is set in the transmission unit (30), and the fiber bundle (20) is transmitted to the microwave processing unit (40) by the transmission unit (30). Let through,
c. Starting up the microwave processing unit (40): controlling the microwave conditions in the microwave processing unit (40);
d. Start-up of the transmission unit (30): The transmission unit (30) sends the fiber bundle (20) and processes the fiber bundle (20) for a continuous time under the microwave condition, and then converts the fiber bundle (20) to the oxidized fiber. Make a bundle (20A)
Procedure is included,
The fiber bundle (20) is continuously irradiated by the microwave processing unit (40) while passing through the heating furnace (33) by repeating lap winding,
In the repetition of the lap winding, the fiber bundle (20) enters the heating furnace (33) from the front of the heating furnace (33) and is sent to the rear of the heating furnace (33). The fiber bundle (20) is sent from the rear part of the heating furnace (33) to the front part of the heating furnace (33), and again, the fiber bundle (20) is sent from the front part of the heating furnace (33). Sent to the rear of the heating furnace (33) ,
The transmission unit (30) includes a supply device (31) for supplying the fiber bundle (20), and a feeding device (31) for pulling the fiber bundle (20) and continuously feeding the fiber bundle (20) through the heating furnace (33). A winding device (32),
The microwave processing unit (40) supplies the heating furnace (33) with a magnetron (41) for generating a microwave frequency and the microwave output, and supplies the atmosphere gas to the heating furnace (33). An air supply device (42) for performing
The winding device (32), the magnetron (41) and the air supply device (42) are electrically connected to a control unit (50) .
A method for producing oxidized fibers. The microwave conditions are a microwave frequency of 300 to 300,000 MHz, a microwave output of 1 to 1000 kW / m ² , a working temperature of 100 to 600 ° C., and any one of oxygen, air, and ozone or a mixture thereof. Characterized by containing atmospheric gas,
A method for producing an oxidized fiber according to claim 5 . The processing time is 1 to 40 minutes,
A method for producing an oxidized fiber according to claim 6 . The microwave power is 10 to 24 kW / m ² ,
A method for producing an oxidized fiber according to claim 6 . The microwave frequency is 2000-3000 MHz, and the working temperature is 150-350 ° C.,
A method for producing an oxidized fiber according to claim 6 . The fiber bundle (20) may be any one of polyacrylonitrile (PAN) fiber, bitumen fiber, and other organic fibers.
A method for producing an oxidized fiber according to claim 5 . A heating unit (34) is provided inside the heating furnace (33).
A method for producing an oxidized fiber according to claim 5 . The heat retaining unit (34) may be made of any one of a metal oxide, a carbide, a microwave highly reactive material, or a combination thereof.
A method for producing an oxidized fiber according to claim 11 .

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