JP2004360079A - Method for producing precursor, flameproofed fiber and carbon fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide methods for producing a precursor for a highly oriented and high-strength carbon fiber and the carbon fiber with which the operation conditions of an apparatus for production is stabilized. <P>SOLUTION: The method for producing the precursor is carried out as follows. A steam treatment of the precursor drawn by varying the steam temperature at an optional draw ratio is conducted at a temperature within the temperature range of (T-4) to (T+6)°C including a temperature T°C exhibiting the maximum specific gravity of a specific gravity-steam treating temperature curve determined under measuring conditions of 250°C, 1 h and a constant length and at the draw ratio, etc., at that time. Furthermore, the method for producing the carbon fiber comprises flame-proofing the precursor in an oxidizing gas atmosphere, providing the flameproofed fiber and then heat-treating the resultant flameproofed fiber in an inert gas atmosphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１２０】
【発明の効果】
本発明のプリカーサーの製造方法によれば、任意の延伸倍率においてスチーム温度を変えて延伸したプリカーサーを２５０℃で１ｈｒ且つ定長の測定条件で求めた比重（２５０℃／１ｈｒ定長処理比重）−スチーム処理温度曲線の最大比重を示す温度Ｔ℃を含み（Ｔ−４）〜（Ｔ＋６）℃の範囲内の温度とその時の延伸倍率でスチーム処理を、又は、任意のスチーム温度において延伸倍率を変えて延伸したプリカーサーの２５０℃／１ｈｒ定長処理比重−スチーム処理温度曲線の最大比重を示す延伸倍率であって最も低い延伸倍率Ｐ倍を含み（Ｐ−１．５）〜（Ｐ＋０．５）倍の範囲内の延伸倍率及びその時の温度でスチーム処理をするようにしているので、スチーム延伸処理するに際し、更に後工程の耐炎化繊維及び炭素繊維製造の際において、毛羽や糸切れを低減させ、製造装置の運転状態を安定化させることができる。
【０１２１】
また、本発明の製造方法によって得られるプリカーサー、耐炎化繊維及び炭素繊維は、高配向、高強度のものである。
【図面の簡単な説明】
【図１】検討例１における各スチーム延伸条件で得たプリカーサーについて、スチーム温度と２５０℃／１ｈｒ比重との関係を示すグラフである。
【図２】検討例１における各スチーム延伸条件で得たプリカーサーについて、スチーム温度とＴＭＡ収縮応力との関係を示すグラフである。
【図３】検討例１における各スチーム延伸条件で得たプリカーサーについて、スチーム温度と１５０℃／１ｈｒ収縮率との関係を示すグラフである。
【図４】検討例２における各スチーム延伸条件で得たプリカーサーについて、延伸倍率と２５０℃／１ｈｒ比重との関係を示すグラフである。
【図５】検討例１、２における各スチーム延伸条件で得たプリカーサーについて、引続き耐炎化処理した時のプリカーサーの耐炎化処理時間とＴｇ温度との関係を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a precursor (precursor fiber) for producing an oxidized fiber and a carbon fiber, and a method for producing an oxidized fiber and a carbon fiber using the precursor.
[0002]
[Prior art]
Usually, a precursor for producing carbon fiber is produced by further stretching a coarse precursor obtained by solidifying a spinning solution discharged from a nozzle into a coagulating solution.
[0003]
In order to obtain a precursor for the production of highly oriented, high-strength flame-resistant fibers and carbon fibers, it is desirable that the stretching ratio of the coarse precursor is appropriately high, so that the stretching operation is performed in a relatively high-temperature bath or steam. Is being done. Depending on the drawing conditions, the properties of the obtained precursor are greatly affected, and thus have a great influence on the properties of the obtained oxidized fiber and carbon fiber. Studies have been made on stretching conditions (for example, Patent Documents 1 to 3).
[0004]
[Patent Document 1]
JP-A-10-292240 (Claims)
[Patent Document 2]
JP-A-8-158162 (Claims)
[Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-345429 (Claims)
[0005]
[Problems to be solved by the invention]
The present inventor spinned the spinning solution, stretched it in a bath as necessary, and further dried and densified it as necessary to obtain a crude precursor. The precursor was obtained by stretching the crude precursor while changing the steam temperature at an arbitrary stretching ratio. Using this stretched precursor, the specific gravity (250 ° C./1 hr constant-length treatment specific gravity) was determined at 250 ° C. for 1 hr and at a constant length measurement condition. In the graph showing the relationship between the specific gravity of 250 ° C./1 hr and the steam processing temperature at that time (250 ° C./1 hr specific gravity-steam processing temperature curve), the steam is drawn at a temperature within a predetermined range from the temperature showing the maximum specific gravity and the draw ratio at that time. The stretching ratio within a predetermined range from the stretching ratio indicating the maximum specific gravity of the constant-temperature-specific-gravity treatment-steam-processing temperature curve at 250 ° C./1 hr of the precursor stretched by changing the stretching ratio at an arbitrary steam temperature and the temperature at that time It has been found that a precursor capable of producing a carbon fiber having a high strength and a high degree of orientation can be obtained by performing the steam treatment with, and the present invention has been completed.
[0006]
Therefore, it is an object of the present invention to solve the above-mentioned problems and to provide a highly oriented, high-strength flame-resistant fiber and a precursor for producing carbon fiber, and a method for producing the flame-resistant fiber and carbon fiber using the precursor. Is to provide.
[0007]
[Means for Solving the Problems]
The present invention that achieves the above object is as described below.
[0008]
[1] Including a temperature T ° C. showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C. for 1 hour and under a constant length measurement condition using a precursor stretched by changing the steam temperature at an arbitrary stretching ratio (T -4) to perform steam treatment at a temperature in the range of (T + 6) ° C. and a draw ratio at that time, or at 250 ° C. for 1 hour and a constant length using a precursor drawn by changing the draw ratio at an arbitrary steam temperature. The steam treatment is performed at the draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P, which indicates the maximum specific gravity of the specific gravity-steam treatment temperature curve obtained under the measurement conditions, and the temperature at that time. A method for producing a precursor.
[0009]
[2] Including the temperature S ° C indicating the maximum shrinkage stress load of the TMA shrinkage stress load at 150 ° C-steam treatment temperature curve obtained by TMA constant length measurement using the stretched precursor (S-5) to (S + 5) The method for producing a precursor according to [1], wherein steam treatment is performed at a temperature in the range of ° C. and a draw ratio at that time.
[0010]
[3] The temperature of the stretched precursor is 150 ° C. for 1 hour and the minimum shrinkage rate of the steam treatment temperature curve obtained under the conditions of a free load and a shrinkage rate of R ° C. is from (R-5) to (R + 5) ° C. The method for producing a precursor according to [2], wherein steam treatment is performed at the temperature and the draw ratio at that time.
[0011]
[4] Including a temperature T ° C. showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C. for 1 hour using a precursor stretched by changing the steam temperature at an arbitrary draw ratio under a constant length (T -4) Steam treatment at a temperature in the range of (T + 6) ° C. and a draw ratio at that time, or measurement at 250 ° C. for 1 hour and a constant length using a precursor drawn by changing the draw ratio at an arbitrary steam temperature. The steam treatment was performed at the draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve obtained under the conditions, and the temperature at that time. To obtain a precursor, and then subjecting the precursor to an oxidizing gas atmosphere with a flame resistance treatment at a specific gravity of the precursor of 1.14 to 1.25 and a stretching ratio of 1.00 to 1.10. A method for producing a flame-resistant fiber.
[0012]
[5] At the time of the flame-proof treatment, the precursor is stretched so that the degree of orientation in wide-angle X-ray measurement (diffraction angle 17 °) does not decrease while the specific gravity of the precursor is 1.18 to 1.21 [4] 3. The method for producing an oxidized fiber according to item 1.
[0013]
[6] The method for producing an oxidized fiber according to [4], wherein the oxidized fiber is subjected to an oxidization treatment at a draw ratio of 1.00 to 1.10 while the glass transition temperature of the precursor continues to decrease during the oxidization treatment.
[0014]
[7] Including a temperature T ° C. showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C. for 1 hour using a precursor stretched while changing the steam temperature at an arbitrary stretching ratio under a constant length (T -4) Steam treatment at a temperature in the range of (T + 6) ° C. and a draw ratio at that time, or measurement at 250 ° C. for 1 hour and a constant length using a precursor drawn by changing the draw ratio at an arbitrary steam temperature. The steam treatment was performed at the draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve obtained under the conditions, and the temperature at that time. To obtain a precursor, after which the precursor is oxidized in an oxidizing gas atmosphere to obtain an oxidized fiber, and then the oxidized fiber is heat-treated in an inert gas atmosphere. Method for producing carbon fiber.
[0015]
[8] Including a temperature T ° C. showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C. for 1 hour using a precursor stretched while changing the steam temperature at an arbitrary draw ratio under a constant length (T -4) Steam treatment at a temperature in the range of (T + 6) ° C. and a draw ratio at that time, or measurement at 250 ° C. for 1 hour and a constant length using a precursor drawn by changing the draw ratio at an arbitrary steam temperature. The steam treatment was performed at the draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve obtained under the conditions, and the temperature at that time. To obtain a precursor, and then subjecting the precursor to an oxidizing gas atmosphere with a flame resistance treatment at a specific gravity of the precursor of 1.14 to 1.25 and a stretching ratio of 1.00 to 1.10. And obtaining a fire-resistant fiber, and then heat-treating the fire-resistant fiber in an inert gas atmosphere.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
<Determination of manufacturing conditions>
The present invention determines a stretching condition such as a stretching temperature (steam temperature) and a stretching ratio of a coarse precursor in the production of a precursor, thereby producing a good precursor, and a method of subjecting the precursor to flame-resistant treatment and carbonization. The present invention relates to a method for producing carbon fibers by treating.
[0018]
The above stretching conditions are determined by first measuring the relationship between the specific gravity at 250 ° C./1 hr and the steaming temperature for a precursor obtained by repeatedly performing steam stretching at a predetermined arbitrary stretching ratio while changing the steam temperature. Then, a 250 ° C./1 hr constant-length treatment specific gravity-steam treatment temperature curve is obtained. The specific gravity at 250 ° C./1 hr constant-length treatment is a specific gravity determined at 250 ° C. for 1 hr and a constant-length measurement condition using a precursor under each of the above stretching conditions.
[0019]
From the thus obtained 250 ° C./1 hr constant-length treatment specific gravity-steam treatment temperature curve (see FIG. 1), a steam temperature T ° C. showing the maximum specific gravity is determined.
[0020]
Alternatively, the relationship between the specific gravity of the constant-length treatment at 250 ° C./1 hr and the steam treatment temperature was measured for the precursor obtained by repeatedly performing the steam stretching treatment while changing the stretching ratio in steam at a predetermined temperature. / Lhr constant-length processing specific gravity-steam processing temperature curve is determined. From the thus obtained 250 ° C./1 hr constant length treatment specific gravity-steam treatment temperature curve (see FIG. 4), a draw ratio P times showing the maximum specific gravity is determined.
[0021]
(T-4) to (T + 6) ° C. is determined from the obtained T ° C., and the temperature and the draw ratio at that time are determined, or (P−1.5) to (P + 0.5) from the obtained P times. ) Is determined, and the stretching ratio and the temperature at that time are determined as the optimum precursor production conditions.
[0022]
<Manufacture of precursor>
Examples of the precursor for producing the flame-resistant fiber and the carbon fiber of the present invention include polyacrylonitrile (PAN) -based, pitch-based, phenol-based, and rayon-based ones. PAN-based ones provide the highest strength flame-resistant fibers and carbon fibers.
[0023]
This PAN-based precursor is obtained by spinning a PAN-based polymer by a conventional method, stretching in a bath as necessary, further drying and densifying as necessary, and further adjusting the water content as necessary to obtain a crude precursor. These steps themselves are well known to those skilled in the art, for example, those described in JP-A-2002-309438.
[0024]
As the PAN-based polymer, a homopolymer of acrylonitrile and a PAN-based copolymer obtained by copolymerizing a polar monomer such as itaconic acid, methacrylic acid, and acrylic acid at 5% by mass or less can be used.
[0025]
The above crude precursor is sent to a steam stretching machine after its moisture content is adjusted if necessary, and is stretched in the steam (steam stretching).
[0026]
In steam stretching, the precursor is stretched at an arbitrary stretching ratio while changing the steam temperature. Using these stretched precursors, the specific gravity (250 ° C./1 hour constant-length treatment specific gravity) is determined at 250 ° C. for 1 hr and under the constant length measurement conditions. A 250 ° C./1 hr constant length processing specific gravity-steam processing temperature curve is created from the 250 ° C./1 hr constant length processing specific gravity and the steam processing temperature at that time (see FIG. 1).
[0027]
This 250 ° C./1 hr constant length processing specific gravity-steam processing temperature curve shows that the 250 ° C./1 hr constant length processing specific gravity increases as the steam temperature increases below a certain steam processing temperature, and the steam processing temperature increases above the steam processing temperature. The higher the temperature, the lower the specific gravity at 250 ° C./hr for the constant length treatment.
[0028]
That is, the method for producing a precursor according to the present invention includes a temperature T ° C which indicates the maximum specific gravity of a 250 ° C / 1 hr constant length processing specific gravity-steam processing temperature curve, and a temperature in the range of (T-4) to (T + 6) ° C. It is characterized in that steam treatment is performed at the stretching ratio at that time.
[0029]
The precursor stretched under the steam stretching conditions has good packing. On the other hand, if the packing is poor, not only the specific gravity (density) of the obtained oxidized fiber becomes low, but also it becomes difficult to finally obtain high-strength carbon fiber. In addition, it causes fluff in the firing step.
[0030]
In order to further improve the packing of the precursor, the coarse precursor is, in addition to the steam stretching conditions, using a precursor stretched by changing the steam temperature at an arbitrary stretching ratio, at 150 ° C. determined by TMA constant length measurement. The temperature range of (S-5) to (S + 5) ° C, preferably the temperature range of (S-4) to (S + 4) ° C, including the temperature S ° C indicating the maximum shrinkage stress in the TMA shrinkage stress-steam treatment temperature curve. It is desirable to carry out steam treatment at a draw ratio of (see FIG. 2).
[0031]
The precursor obtained by this steam stretching has a large TMA shrinkage stress at 150 ° C., as determined by TMA constant length measurement, but has a small actual shrinkage (under free load conditions). In other words, although the force to shrink in the intermolecular force interaction in the precursor is strong, the packing is firm, so that it is hardly shrunk in practice (slightly shrinks). In other words, this precursor has a packing structure that does not easily shrink under the conditions of the oxidation resistance treatment under a free load.
[0032]
Therefore, in addition to the steam stretching conditions, the crude precursor is obtained by subjecting a precursor stretched by changing the steam temperature at an arbitrary stretching magnification to 150 ° C. for 1 hour and subjected to oxidizing treatment under the conditions of a free load—the shrinkage ratio−steam Including the temperature R ° C showing the minimum shrinkage of the processing temperature curve, the temperature range is (R-5) to (R + 5) ° C, preferably the temperature range (R-4.5) to (R + 5) ° C, and more preferably (R−5) to (R + 5) ° C. It is desirable to carry out steam treatment in a temperature range of R-4) to (R + 5) ° C. and a draw ratio at that time (see FIG. 3).
[0033]
<Manufacture of flame-resistant fiber>
The precursor that has been drawn under the above conditions is subjected to a heat treatment in an oxidizing gas atmosphere to become an oxidized fiber. As described above, the precursor before the oxidizing treatment has good packing, and the oxidized fiber obtained also has good packing. The flame-resistant fiber has high orientation and high strength, and is a fiber with little fluff or breakage.
[0034]
In order to further improve the physical properties such as the packing structure, the degree of orientation, and the strength of the obtained flame-resistant fiber, the precursor is preferably subjected to a flame-proof treatment so that the orientation is not loosened.
[0035]
Specifically, it is preferable that the precursor be subjected to flame-resistant treatment at a specific gravity during processing of 1.14 to 1.25 and a stretching ratio of 1.00 to 1.10.
[0036]
During the flame-proofing treatment, the precursor is preferably subjected to the flame-proofing treatment at a stretching ratio of 1.00 to 1.10. While its glass transition temperature (Tg temperature) continues to decrease.
[0037]
Among the known means for determining the Tg temperature, in the present invention, it is preferable to use a dynamic viscoelasticity measuring means. Specifically, the peak temperature of the loss tangent (tan δ) representing the scale of the loss storage modulus (E ″) with respect to the storage modulus (E ′) is defined as the Tg temperature of the precursor. The relationship with the Tg temperature is as shown in FIG.
[0038]
At the time of the above-mentioned flameproofing treatment, the precursor may be stretched so that the degree of orientation in wide-angle X-ray measurement (diffraction angle 17 °) does not decrease while the specific gravity is 1.18 to 1.21. preferable.
[0039]
The degree of orientation in wide-angle X-ray measurement (diffraction angle 17 °) can be obtained as follows.
[0040]
Approximately 12,000 single fibers of the precursor after the drawing treatment are bundled, and the fibers are aligned in the fiber axis direction while converging the bundle with acetone.
[0041]
The fiber is stuck on a backing with a hole of 1.0 cm in diameter such that the center of the fiber bundle is in the center of the hole while the fibers are in tension. Then, the mount is fixed to the sample adjusting jig so that the fiber axis and the jig axis are parallel to each other.
[0042]
Further, this jig is fixed to a sample table for wide-angle X-ray diffraction measurement by a transmission method. When a sample is irradiated with Cu Kα radiation as an X-ray source, a diffraction pattern (having two peaks) appears around 2θ17 °.
[0043]
The peak angles of the diffraction pattern are obtained, and the measurement is performed in a range of 360 degrees including those angles. Then, a base line is drawn on the graph of the obtained X-ray diffraction chart, and the peak half width H _1/2 , H ' _1/2 (Degrees)
[0044]
(Equation 1)
Degree of orientation = [360− (H _1/2 + H ' _1/2 )] / 360 (1)
To calculate the degree of orientation.
[0045]
<Manufacture of carbon fiber>
Next, the oxidized fiber may be heat-treated in an inert gas atmosphere to become a carbon fiber. Furthermore, it is preferable to perform a sizing treatment for the purpose of facilitating post-processing of the carbon fiber and improving the handleability. The sizing method can be performed by a conventionally known method, and it is preferable that the sizing agent is used after changing the composition as appropriate according to the application, and that the sizing agent is uniformly adhered and then dried.
[0046]
The carbon fiber obtained in this manner is a carbon fiber having high orientation and high strength, and having less fluff and thread breakage.
[0047]
【Example】
Hereinafter, the present invention will be described more specifically with reference to study examples, examples, and comparative examples. Moreover, the evaluation method of the various physical properties of the precursor, the oxidized fiber and the carbon fiber after stretching in each of the examination examples, examples and comparative examples was carried out by the method described above or the following method.
[0048]
<250 ° C / 1hr constant length processing specific gravity>
It was measured by the following method.
1. Take a certain length of precursor and fix it firmly so that the length does not change.
2. Place in a hot air circulating dryer set at 250 ° C. and treat for 1 hour.
3. After being taken out and allowed to cool, measurement is performed by the Archimedes method. The sample fiber is degassed in acetone and measured.
[0049]
<TMA shrinkage stress>
The measurement was performed by the following method using a thermomechanical property tester (TMA) 4000S manufactured by Mac Science.
1. The precursor is collected and fixed to a fiber measuring jig as an effective length of 1 cm.
2. The constant-length mode is set, and the load is measured between 25 and 400 ° C. at a heating rate of 20 ° C./min.
3. The measured load at 150 ° C (150 ° C measured load) is calculated by the following formula.
[0050]
(Equation 2)
TMA shrinkage stress = 150 ° C. Measured load / precursor sample cross-sectional area is converted to fiber cross-sectional area to obtain TMA shrinkage stress.
[0051]
<150 ° C / 1hr shrinkage>
It was measured by the following method.
1. Measure 1 m of the precursor.
2. The precursor is placed on a wire mesh shelf in a free state, and is placed in a hot air circulating dryer set at 150 ° C.
3. One hour later, the sample is taken out, the sample length is measured, and the shrinkage is determined.
4. The measurement is performed with n = 3, and the average value is obtained.
[0052]
<Glass transition temperature (Tg)>
It was measured by a dynamic viscoelasticity measuring device.
[0053]
The measurement was performed between 0 and 180 ° C. using a dynamic viscoelasticity measuring apparatus manufactured by UBM Co., Ltd., model: Rhogl E-4000, at a temperature rising rate of 3 ° C./min and a frequency of 3 Hz. As a measurement sample, 12,000 precursor fiber bundles and 25 mm were used.
[0054]
<Degree of orientation in wide-angle X-ray measurement (diffraction angle 17 °)>
X-ray diffractometer: Using RINT2050 manufactured by Rigaku Denki, the degree of orientation at a diffraction angle of 17 ° was measured at a half width H _1/2 , H ' _1/2 From the above equation (1).
[0055]
<Degree of orientation in wide-angle X-ray measurement (diffraction angle 26 °)>
The degree of orientation was determined in the same manner as in the above-mentioned wide-angle X-ray measurement (diffraction angle: 17 °) except that the diffraction angle was 26 °.
[0056]
<Tensile strength>
It was measured by the method specified in JIS R 7601.
[0057]
<Precursor specific gravity>
It was measured by the Archimedes method. The sample fiber was degassed in acetone and measured.
[0058]
Study example 1
A stock spinning solution of a copolymer consisting of 95% by mass of acrylonitrile / 4% by mass of methyl acrylate / 1% by mass of itaconic acid was wet- or dry-wet spinning, washed with water and dried to obtain a crude precursor having a fiber diameter of 22.0 μm. The crude precursor is sent to a steam stretching machine, where the stretching ratio is 5.5 times, and the steam temperature (treatment temperature) is 107 ° C., 110 ° C., 113 ° C., 117 ° C., 120 ° C., 123 ° C., and 127 ° C. under steam stretching conditions. Then, precursors having various physical properties shown in FIGS. 1 to 3 were obtained.
[0059]
FIG. 1 shows the specific gravity (250 ° C./1 hr constant-length specific gravity) of the oxidized fiber obtained by oxidizing the precursor obtained at each of the above steam stretching conditions at 250 ° C. for 1 hour and at a constant length. 5 is a graph (250 ° C./1 hr constant length processing specific gravity-steam processing temperature curve) obtained by plotting the processing temperature during steam stretching.
[0060]
As shown in FIG. 1, at a steam temperature of 115 ° C. or lower, the specific gravity of the 250 ° C./1 hr constant-length treatment increases as the steam temperature increases, and at a steam temperature of 116 ° C. or higher, the specific gravity of the 250 ° C./hr constant-length treatment increases as the steam temperature increases. Fell. As described above, at a steam temperature of 115 ° C. (T ° C.) T ° C. and a temperature of 111 (T-4) to 121 (T + 6) ° C., at which the specific gravity of the 250 ° C./1 hr constant length treatment is the maximum, the 250 ° C./1 hr constant length treatment specific gravity. Was 1.35 or more.
[0061]
FIG. 2 shows that the precursor obtained under each of the above-mentioned steam stretching conditions was subjected to a flameproofing treatment at 150 ° C. and a fixed length in TMA, and the stress (TMA shrinkage stress) applied to the precursor during the treatment and the time of steam stretching. It is the graph obtained by plotting processing temperature.
[0062]
As shown in FIG. 2, when the steam temperature is 116 ° C. or lower, the TMA shrinkage stress increases as the steam temperature increases, and when the steam temperature is 116 ° C. or higher, the TMA shrinkage stress decreases as the steam temperature increases. As described above, in the range of 111 (S-5) to 121 (S + 5) ° C. including the steam temperature of 116 ° C. (S ° C.) at which the TMA shrinkage stress becomes maximum (37 MPa), the TMA shrinkage stress is 35.1 MPa (37 MPa). -5%) or more.
[0063]
FIG. 3 shows that the precursor obtained under each of the above-mentioned steam stretching conditions was subjected to a flameproofing treatment at 150 ° C. for 1 hour and under a free load, and the precursor shrinkage rate (150 ° C./1 hr shrinkage rate) in the treatment and the steam stretching time. 3 is a graph obtained by plotting the processing temperature of the present invention.
[0064]
As shown in FIG. 3, when the steam temperature is 116 ° C. or lower, the higher the steam temperature, the lower the 150 ° C./1 hr shrinkage ratio. Rose. As described above, 150 ° C./1 hr shrinkage in the range of 111 (R−5) to 121 (R + 5) including the steam temperature of 116 ° C. (R ° C.) at which the 150 ° C./1 hr shrinkage rate becomes the minimum (8.5%). The rate was less than 8.84% (8.5% +4%)%.
[0065]
Examples 1-3
Among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained under the conditions of a draw ratio of 5.5 times, steam temperature (treatment temperature) of 113 ° C., 117 ° C., and 120 ° C. was placed in an oxidizing gas atmosphere. A flame-resistant fiber was produced by performing a flame-proof treatment.
[0066]
During the oxidation treatment of these precursors, the stretching ratio was kept at 1.05 while the specific gravity of the precursor was 1.14 to 1.25.
[0067]
In addition, while the specific gravity of the precursor was 1.18 to 1.21, the film was stretched and flame-proofed so that the degree of orientation in wide-angle X-ray measurement (diffraction angle: 17 °) did not decrease from 89.5%.
[0068]
Further, while the specific gravity of the precursor was 1.15 to 1.20, the glass transition temperature of the precursor continued to decrease from 107.2 ° C. to 97.0 ° C. During this time, the draw ratio was kept at 1.05.
[0069]
At the time of the above-described oxidation treatment, the relationship between the oxidation treatment time of the precursor and the glass transition temperature (Tg temperature) is as shown in FIG.
[0070]
Next, each of the oxidized fibers was subjected to a carbonization treatment to produce carbon fibers. These production conditions and production equipment were conventional.
[0071]
During the production of the flame-resistant fiber and the carbon fiber in the process after the steam stretching, the generation of fluff and breakage was small, and the operation state of the production apparatus could be stabilized.
[0072]
The tensile strength of the carbon fibers obtained from the precursors under the respective steam stretching conditions via the oxidized fibers was 6350 MPa, 6400 MPa, and 6300 MPa at steam temperatures (treatment temperatures) of 113 ° C., 117 ° C., and 120 ° C., respectively. Was.
[0073]
Thus, the tensile strengths of the carbon fibers obtained from the precursors under the respective steam stretching conditions were all high.
[0074]
Further, the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber obtained from the precursor under each steam stretching condition was 78.degree. At a steam temperature (treatment temperature) of 113 ° C., 117 ° C. and 120 ° C., respectively. 1%, 78.0%, and 77.8%. Furthermore, the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the carbon fiber via the oxidized fiber obtained from the precursor under each steam stretching condition was as follows: steam temperature (treatment temperature) 113 ° C, 117 ° C , 120 ° C., respectively, 81.7%, 81.5% and 81.4%.
[0075]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber and the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the carbon fiber obtained from the precursor under each steam stretching condition. Were all high.
[0076]
Comparative Example 1
The same as Examples 1 to 3 except that among the precursors obtained under the respective steam stretching conditions in Study Example 1, the precursor obtained under the conditions of a draw ratio of 5.5 times and a steam temperature (treatment temperature) of 107 ° C. was used. Flame-resistant fibers and carbon fibers were produced under the conditions.
[0077]
The precursor used in this comparative example had a large amount of fluff in the stretching process of the steam stretching process for obtaining the same, and in the carbonization process of baking the precursor after the oxidation treatment. As described above, the operation state of the carbon fiber production device (steam drawing device, carbonization device) could not be stabilized.
[0078]
The tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 6000 MPa.
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 77.5%. Furthermore, the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the above oxidized fiber had a degree of orientation of 81.2% in wide-angle X-ray measurement (diffraction angle: 26 °).
[0079]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber and the wide-angle X-ray measurement of the carbon fiber (diffraction angle: 26 °) obtained from the precursor under the steam stretching conditions of this comparative example. Were all low.
[0080]
Comparative Example 2
The same as Examples 1 to 3 except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained under the conditions of a stretching ratio of 5.5 times and a steam temperature (treatment temperature) of 110 ° C. was used. Flame-resistant fibers and carbon fibers were produced under the conditions.
[0081]
The precursor used in this comparative example had a large amount of fluff during firing in the carbonization step after the oxidation treatment. As described above, the operating state of the carbon fiber production device (carbonization device) could not be stabilized.
[0082]
In addition, the tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 6220 MPa.
[0083]
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 77.8%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of the present comparative example through the above-described oxidized fiber was 81.6%.
[0084]
Comparative Example 3
The same as in Examples 1 to 3, except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained under the conditions of a draw ratio of 5.5 times and a steam temperature (treatment temperature) of 123 ° C. was used. Flame-resistant fibers and carbon fibers were produced under the conditions.
[0085]
The precursor used in this comparative example had a low specific gravity of 1.14, and the specific gravity of the flame-resistant fiber obtained by the flame-resistant treatment was also low. As a result, the carbon fiber obtained by carbonizing the oxidized fiber had a low tensile strength of 6200 MPa.
[0086]
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 77.5%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the above oxidized fiber was 81.3%.
[0087]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber and the wide-angle X-ray measurement of the carbon fiber (diffraction angle: 26 °) obtained from the precursor under the steam stretching conditions of this comparative example. Were all low.
[0088]
Comparative Example 4
The same as in Examples 1 to 3, except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained under the conditions of a draw ratio of 5.5 times and a steam temperature (treatment temperature) of 127 ° C. was used. Flame-resistant fibers and carbon fibers were produced under the conditions.
[0089]
The precursor used in this comparative example had a low specific gravity of 1.12, and also had a low specific gravity of the oxidized fiber obtained by the oxidization treatment. Consequently, the carbon fiber obtained by carbonizing the oxidized fiber had a low tensile strength of 6050 MPa.
[0090]
The precursor used in this comparative example had a low degree of orientation of 90.0% in wide-angle X-ray measurement (diffraction angle 17 °), and wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber obtained from this precursor. Was as low as 77.2%. Furthermore, the carbon fiber obtained from the precursor under the steam stretching conditions of the present comparative example via the above oxidized fiber also has a low degree of orientation of 81.1% in wide-angle X-ray measurement (diffraction angle 26 °). Met.
[0091]
Study example 2
The crude precursor obtained in Study Example 1 was sent to a steam stretching machine, where the steam temperature (treatment temperature) was 113 ° C., the stretching ratio was 3.5, 4.5, 5.0, 5.5, and 6. Steam stretching was performed under the conditions of 0, 6.5, 6.9, and 7.2 times to obtain a precursor for examining the steam stretching conditions.
[0092]
FIG. 4 shows the specific gravity of the oxidized fiber obtained by oxidizing the precursor obtained at each of the above-mentioned steam stretching conditions at 250 ° C. for 1 hr and at a constant length (specific gravity at 250 ° C./1 hr constant-length treatment). It is the graph obtained by plotting the stretching ratio at the time of steam stretching.
[0093]
As shown in FIG. 4, when the draw ratio is 6.0 or less, the specific gravity at 250 ° C./1 hr increases as the draw ratio increases, and when the draw ratio is 6.0 or more, the higher the draw ratio, the higher the draw ratio. C./1 hr. As described above, the stretching ratio at which the specific gravity at 250 ° C./hr for the constant length treatment reaches the maximum (1.362) includes 6.3 times (P times), from 4.8 (P-1.5) to 6.8 (P + 0). In the range of 0.5) times, the specific gravity at 250 ° C./1 hr for the fixed length treatment was 1.35 or more.
[0094]
Examples 4 to 7
Among the precursors obtained under the respective steam stretching conditions of Study Example 2, the precursors were obtained under the conditions of a steam temperature (treatment temperature) of 113 ° C., a stretching ratio of 5.0 times, 5.5 times, 6.0 times, and 6.5 times. The precursor was subjected to a flameproofing treatment and a carbonizing treatment, and flameproofed fibers and carbon fibers were produced in the same manner as in Examples 1 to 3.
[0095]
During the production of carbon fibers in these post-processes, the generation of fluff and yarn breakage was small, and the operation state of the production apparatus could be stabilized.
[0096]
In addition, the tensile strength of the carbon fiber obtained from the precursor of each steam stretching condition via the oxidized fiber was 5.0 times, 5.5 times, 6.0 times, and 6.5 times at the draw ratio. It was 6260 MPa, 6350 MPa, 6390 MPa, 6300 MPa.
[0097]
Thus, the tensile strengths of the carbon fibers obtained from the precursors under the respective steam stretching conditions were all high.
[0098]
The degree of orientation of the oxidized fiber obtained from the precursor under each steam stretching condition in the wide-angle X-ray measurement (diffraction angle: 26 °) was determined to be 5.0 times, 5.5 times, 6.0 times, and 6.0 times. Five-fold, 77.8%, 78.1%, 78.3%, and 78.4%, respectively. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle 26 °) of the carbon fiber obtained from the precursor under each steam stretching condition via the above-described oxidized fiber was determined to be a stretching ratio of 5.0 times, 5.5 times, 6.0 times and 6.5 times, respectively, 81.4%, 81.7%, 82.0, and 82.0%.
[0099]
Thus, the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber obtained from the precursor under each steam stretching condition and the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the carbon fiber are as follows. All were high.
[0100]
Comparative Example 5
The same as Examples 4 to 7 except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained at a steam temperature (treatment temperature) of 113 ° C. and a stretching ratio of 3.5 was used. Under the conditions, an oxidized fiber and a carbon fiber were manufactured.
[0101]
The precursor used in this comparative example had a large amount of fluff in the carbonization step of baking it after the oxidization treatment. As described above, the operation state of the carbon fiber production device (steam drawing device, carbonization device) could not be stabilized.
[0102]
In addition, the tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 5700 MPa.
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 76.8%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of the present comparative example via the above-described oxidized fiber was 80.4%.
[0103]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber and the wide-angle X-ray measurement of the carbon fiber (diffraction angle: 26 °) obtained from the precursor under the steam stretching conditions of this comparative example. Were all low.
[0104]
Comparative Example 6
The same as Examples 4 to 7 except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained at a steam temperature (treatment temperature) of 113 ° C. and a stretching ratio of 4.5 was used. Under the conditions, an oxidized fiber and a carbon fiber were manufactured.
[0105]
The precursor used in this comparative example could not stabilize the operation state of the carbon fiber production device (steam drawing device, carbonization device).
[0106]
In addition, the tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 6100 MPa.
[0107]
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 77.5%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was 80.9%.
[0108]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber and the wide-angle X-ray measurement of the carbon fiber (diffraction angle: 26 °) obtained from the precursor under the steam stretching conditions of this comparative example. Were all low.
[0109]
Comparative Example 7
The same as Examples 4 to 7 except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained at a steam temperature (treatment temperature) of 113 ° C. and a stretching ratio of 6.9 times was used. Under the conditions, an oxidized fiber and a carbon fiber were manufactured.
[0110]
The precursor used in this comparative example had a large amount of fluff in the carbonization step of baking it after the oxidization treatment. As described above, the operation state of the carbon fiber production device (steam drawing device, carbonization device) could not be stabilized.
[0111]
In addition, the tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 6200 MPa.
[0112]
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 78.2%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of the present comparative example through the above-described oxidized fiber was 81.6%.
[0113]
Comparative Example 8
The same as Examples 4 to 7 except that among the precursors obtained under the respective steam stretching conditions of Study Example 1, the precursor obtained under the conditions of a steam temperature (treatment temperature) of 113 ° C. and a stretching ratio of 7.2 was used. Under the conditions, an oxidized fiber and a carbon fiber were manufactured.
[0114]
The precursor used in this comparative example had a large amount of fluff in the stretching process of the steam stretching process for obtaining the same, and in the carbonization process of baking the precursor after the oxidation treatment. As described above, the operation state of the carbon fiber production device (steam drawing device, carbonization device) could not be stabilized.
[0115]
The tensile strength of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was as low as 6000 MPa.
[0116]
Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber obtained from the precursor under the steam drawing conditions of this comparative example was 77.9%. Furthermore, the degree of orientation in wide-angle X-ray measurement (diffraction angle: 26 °) of the carbon fiber obtained from the precursor under the steam stretching conditions of this comparative example via the oxidized fiber was 81.0%.
[0117]
As described above, the degree of orientation in the wide-angle X-ray measurement (diffraction angle: 26 °) of the oxidized fiber and the wide-angle X-ray measurement of the carbon fiber (diffraction angle: 26 °) obtained from the precursor under the steam stretching conditions of this comparative example. Were all low.
[0118]
Table 1 shows steam stretching conditions, production process conditions, and obtained carbon fiber evaluations in Examples 1 to 7 and Comparative Examples 1 to 8.
[0119]
[Table 1]

[0120]
【The invention's effect】
According to the precursor manufacturing method of the present invention, the specific gravity of the precursor stretched by changing the steam temperature at an arbitrary stretching ratio at 250 ° C. for 1 hr and the constant length measurement condition (250 ° C./1 hr constant length processing specific gravity) − The steam treatment is performed at a temperature in the range of (T-4) to (T + 6) ° C. including the temperature T ° C. indicating the maximum specific gravity of the steam treatment temperature curve and the draw ratio at that time, or the draw ratio is changed at an arbitrary steam temperature. Stretching ratio showing the maximum specific gravity of the 250 ° C./1 hr constant length treatment specific gravity-steam treatment temperature curve of the precursor stretched by stretching, including the lowest draw ratio P times (P-1.5) to (P + 0.5) times The steam treatment is performed at the draw ratio and the temperature at that time in the range of the above. Te reduces fuzz and yarn breakage, it is possible to stabilize the operation state of the manufacturing apparatus.
[0121]
Further, the precursor, the oxidized fiber and the carbon fiber obtained by the production method of the present invention have high orientation and high strength.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between steam temperature and specific gravity at 250 ° C./1 hr for a precursor obtained under each steam stretching condition in Study Example 1.
FIG. 2 is a graph showing the relationship between steam temperature and TMA shrinkage stress for a precursor obtained under each steam stretching condition in Study Example 1.
FIG. 3 is a graph showing the relationship between the steam temperature and the shrinkage at 150 ° C./1 hr for the precursor obtained under each steam stretching condition in Study Example 1.
FIG. 4 is a graph showing the relationship between the stretching ratio and the specific gravity at 250 ° C./1 hr for the precursor obtained under each steam stretching condition in Study Example 2.
FIG. 5 is a graph showing the relationship between the oxidizing treatment time of the precursor and the Tg temperature when the oxidizing treatment was performed on the precursors obtained under the respective steam stretching conditions in Study Examples 1 and 2.

Claims (8)

Including a temperature T ° C showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C for 1 hour and under a constant length measurement condition using a precursor stretched by changing the steam temperature at an arbitrary draw ratio (T-4). Steam treatment at a temperature in the range of (T + 6) ° C. and a stretching ratio at that time, or under a measuring condition of 1 hour and a constant length at 250 ° C. using a precursor stretched by changing the stretching ratio at an arbitrary steam temperature. The steam treatment is carried out at a draw ratio in the range of (P-1.5) to (P + 0.5) times including a draw ratio P times showing the maximum specific gravity of the obtained specific gravity-steam treatment temperature curve and the temperature at that time. Manufacturing method of precursor. Including the temperature S ° C indicating the maximum shrinkage stress of the TMA shrinkage stress at 150 ° C-steam treatment temperature curve obtained by TMA constant length measurement using the stretched precursor, within the range of (S-5) to (S + 5) ° C. The method for producing a precursor according to claim 1, wherein steam treatment is performed at a temperature and a draw ratio at that time. A temperature in the range of (R-5) to (R + 5) ° C, including the temperature R ° C showing the minimum shrinkage rate of the shrinkage rate-steam treatment temperature curve obtained at 150 ° C for 1 hour and a free load at 150 ° C. The method for producing a precursor according to claim 2, wherein steam treatment is performed at the stretching ratio at that time. Including a temperature T ° C showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C for 1 hour and under a constant length measurement condition using a precursor stretched by changing the steam temperature at an arbitrary draw ratio (T-4). To steam treatment at a temperature within the range of (T + 6) ° C. and a draw ratio at that time, or using a precursor stretched by changing the draw ratio at an arbitrary steam temperature, at 250 ° C. for 1 hr and under a constant length measurement condition. The precursor is subjected to steam treatment at a draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve, and the precursor at that time. Then, the precursor is subjected to oxidizing treatment in an oxidizing gas atmosphere at a specific gravity of the precursor of 1.14 to 1.25 and a stretching ratio of 1.00 to 1.10. Method for producing a flame-resistant fiber characterized. 5. The flame-resistant treatment according to claim 4, wherein during the flame-resistance treatment, the precursor is stretched so that the degree of orientation in wide-angle X-ray measurement (diffraction angle 17 °) is not reduced while the specific gravity of the precursor is 1.18 to 1.21. 6. Method for producing flame-resistant fiber. The method for producing an oxidized fiber according to claim 4, wherein during the oxidization treatment, the oxidization treatment is performed at a draw ratio of 1.00 to 1.10 while the glass transition temperature of the precursor continues to decrease. Including a temperature T ° C showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C for 1 hour and under a constant length measurement condition using a precursor stretched by changing the steam temperature at an arbitrary draw ratio (T-4). To steam treatment at a temperature within the range of (T + 6) ° C. and a draw ratio at that time, or using a precursor stretched by changing the draw ratio at an arbitrary steam temperature, at 250 ° C. for 1 hr and under a constant length measurement condition. The precursor is subjected to steam treatment at a draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve, and the precursor at that time. Obtaining, after that, the precursor is subjected to an oxidizing gas atmosphere in an oxidizing gas atmosphere to obtain an oxidized fiber, and thereafter, the oxidized fiber is heat-treated in an inert gas atmosphere. Method of manufacturing carbon fiber. Including a temperature T ° C showing the maximum specific gravity of a specific gravity-steam treatment temperature curve obtained at 250 ° C for 1 hour and under a constant length measurement condition using a precursor stretched by changing the steam temperature at an arbitrary draw ratio (T-4). To steam treatment at a temperature within the range of (T + 6) ° C. and a draw ratio at that time, or using a precursor stretched by changing the draw ratio at an arbitrary steam temperature, at 250 ° C. for 1 hr and under a constant length measurement condition. The precursor is subjected to steam treatment at a draw ratio in the range of (P-1.5) to (P + 0.5) times including the draw ratio P times showing the maximum specific gravity of the specific gravity-steam treatment temperature curve, and the precursor at that time. After that, the precursor is subjected to oxidizing treatment in an oxidizing gas atmosphere at a specific gravity of the precursor of 1.14 to 1.25 and a stretching ratio of 1.00 to 1.10. The method of producing a carbon fiber characterized by fibers give, heat treated then the oxidized fiber in an inert gas atmosphere.

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