JP4723710B2 - Method for producing acrylonitrile-based spinning dope, method for producing acrylonitrile-based fiber, and method for producing carbon fiber - Google Patents

Description

【００３９】
上述した実施例及び比較例からも明らかなように、本発明によれば、低温で均一に溶解することができるため、炭素繊維にしたときも容易に高強度と高弾性率を発現し得る炭素
繊維用アクリロニトリル系紡糸原液を、経済性にも優れた方法により製造することができる。
【図面の簡単な説明】
【図１】 本発明の好適な実施形態による重合体溶液の製造装置の半部を切開して示す正面図である。
【符号の説明】
１ 重合体溶液の製造装置
２ シリンダ
２ａ 加熱・冷却流体の流路
３ ロータ
３ａ 加熱・冷却流体の流路
４ 導入口
５ 導出口
６ 溶解室
７ （シリンダ内周面の）ピン部材
８ （ロータ外周面の）ピン部材
Ｐ 定量ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polymer solution, and more particularly to a method for producing an acrylonitrile-based spinning stock solution in which a polymer is uniformly dissolved in a solvent and no gel is formed. The present invention relates to a method of producing A acrylonitrile-based fibers with the said method, and a method for manufacturing a carbon fiber precursor of the same acrylonitrile-based fibers.
[0002]
[Prior art]
Conventionally, as a method for producing an acrylonitrile-based spinning dope, a double-pipe heat exchanger or a multi-tube heat exchanger is used, and a heating medium is passed through the jackets of these heat exchangers, and the acrylonitrile-based polymer and the solvent are mixed. A method is known in which a liquid mixture is heated to dissolve the polymer in the solvent.
[0003]
[Problems to be solved by the invention]
However, in such prior art, temperature spots occur in the tube diameter direction, and the acrylonitrile polymer and its solvent cannot be heated uniformly, so that it is difficult to uniformly dissolve the acrylonitrile polymer. Furthermore, in order to completely dissolve the acrylonitrile-based polymer in the solvent, it is necessary to take a long heating time. Since the polymer and the solvent receive a long heat history, the obtained spinning dope There is also a risk of quality degradation. When heating at a high temperature to shorten the heating time to avoid this, there is a problem that the polymer and its solvent are locally heated in the vicinity of the tube wall, resulting in deterioration of the quality of the spinning dope.
[0004]
In addition, in the process of dissolving acrylonitrile-based polymer in the solvent, the filter life in the process of filtering the spinning dope is short-lived due to the generation of undissolved products caused by non-uniform dissolution of the polymer and degradation products due to local overheating. There are also problems such as the occurrence of yarn breakage in the yarn making process, and fiber defects and associated physical property degradation.
[0005]
The present invention has been made to solve such problems, and an object of the present invention is to uniformly and efficiently dissolve an acrylonitrile polymer in a solvent and to produce a high-quality spinning dope. High-quality acrylonitrile-based polymer solution manufacturing method using polymer solution manufacturing equipment , high-quality acrylonitrile-based precursor fiber for carbon fiber, excellent in spinning and no fiber defects, and high strength Another object of the present invention is to provide a method for producing a high-performance carbon fiber having a high elastic modulus .
[0006]
[Means for solving the problems and effects]
As a result of various investigations by the present inventors to provide a dissolution method capable of dissolving an acrylonitrile-based polymer uniformly and without deterioration in the solvent, the following invention is completed. It came to.
[0007]
That is, the invention according to claim 1 includes a cylinder having an inlet for introducing a mixture of a fixed amount of a polymer and a solvent thereof, and an outlet for deriving the produced polymer solution; A columnar rotor rotatably arranged on the cylinder, and constituting a melting chamber for the polymer in which the gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the rotor is 5 to 50 mm, A large number of pin members protrude from the inner peripheral surface, and a large number of pin members having a distance of 2 to 50 mm protrude from the outer peripheral surface of the rotor so as not to interfere with the pin member of the cylinder. The pin member has a protruding length of 50 to 90% of the gap of the melting chamber, the introduction port is formed in the lower part of the cylinder, and the outlet port is formed in the upper part of the cylinder, and the cylinder and the rotor At least one of , The apparatus for manufacturing a polymer solution comprising a heating and cooling means for heating and cooling the melting chamber, and dispensing the mixture of acrylonitrile polymer and solvent, by rotating the rotor, A method for producing an acrylonitrile-based spinning dope, wherein the mixed solution is uniformly dissolved by heat generation due to uniform dispersion and shearing force .
[0008]
When producing a polymer solution using the above apparatus, first, a mixed solution of a polymer and its solvent is quantitatively introduced into the dissolution chamber from the introduction port. At this time, the rotor is rotating in the cylinder, and the polymer and solvent are uniformly mixed in the mixed liquid introduced into the dissolution chamber by the pin member on the inner peripheral surface of the cylinder and the pin member on the outer peripheral surface of the rotor. At the same time, a shearing force acts on the polymer between the multiple pin members of the cylinder and the rotor. The polymer is uniformly dispersed and efficiently dissolved in the solvent by this shearing force and the heat generated therewith.
[0009]
The introduction port is provided in the lower part of the cylinder, the outlet port is provided in the upper part of the cylinder, the flow direction of the mixed liquid of the polymer and the solvent is set as the antigravity direction, and the introduction pressure and flow rate are controlled, thereby the mixing. The flow rate of the liquid in the dissolution chamber can be accurately and easily controlled. As a result, the liquid mixture supplied from the inlet at the bottom of the cylinder is sufficiently dispersed and uniformly dissolved by the pin member while flowing through the dissolution chamber and reaching the outlet at the top of the cylinder.
[0010]
Wherein at the polymer and a mixture of solvents is heated by the heat generation due to shearing forces as described above, when the temperature of the mixture at this time is lower than the temperature suitable for dissolution of the desired the mixture Raise the temperature to allow for efficient dissolution. On the other hand, when the temperature of the mixed solution becomes higher than the temperature suitable for dissolution due to heat generated by the shearing force, cooling the mixed solution prevents the resulting polymer solution from being deteriorated by overheating. The Thus, accurate and fine temperature control is possible.
[0011]
Further, in order to give a shearing force necessary for the dispersion and dissolution of the polymer and the heat generated therewith to the mixed solution of the polymer and the solvent, the gap between the dissolution chambers, that is, the inner peripheral surface of the cylinder The distance between the outer peripheral surface of the rotor and the outer peripheral surface of the rotor is preferably 5 to 50 mm, and the distance between the pin member protruding from the inner peripheral surface of the cylinder and the pin member protruding from the outer peripheral surface of the rotor is 2 to 50 mm. The protruding length of the pin member is preferably 50 to 90% of the melting chamber gap. Further, the cross-sectional shape of the pin member may be a polygonal shape or a circular shape, but it is desirable that the cross-sectional shape of the pin member be a circle in order to reduce the staying portion around the pin member.
[0012]
By using the polymer solution production apparatus utilizing the above-described shearing force and accompanying heat generation, the acrylonitrile-based polymer can be uniformly dissolved in the solvent. The acrylonitrile-based spinning dope obtained by the dissolution method using shear force is of high quality, and can easily express high strength and high elasticity even when made into carbon fiber, and is economical. It is also an excellent method.
[0013]
Furthermore, if the apparatus is provided with a heating and cooling means for melting chamber, when less heat generation due to shearing force, or by heating the mixture to a desired temperature suitable for dissolution, or shearing force When the generated heat is large, it can be cooled to the desired temperature to prevent overheating. Therefore, there is no problem that the resulting polymer solution is not sufficiently dissolved or deteriorates due to overheating.
[0014]
In addition, as a polymerization method of the acrylonitrile-based polymer of the present invention, any of known methods such as solution polymerization and suspension polymerization can be employed. In addition, as the acrylonitrile-based polymer in the present invention, a polymer in which acrylonitrile is 100%, a polymer obtained by copolymerizing the second component, the third component, and the like can be used. As these copolymerization components, known monomers copolymerizable with acrylonitrile can be used. Specific examples include vinyl acetate, acrylamide, methyl (meth) acrylate, (meth) acrylic acid, itaconic acid, and the like. Moreover, it is preferable that the amount of copolymerization is the grade which does not impair the performance as an acrylic fiber, and specifically, it is preferable that it is about 20 weight% or less. In particular, in the case of an acrylonitrile-based polymer for a precursor fiber for carbon fiber, the amount of the copolymer component is preferably small, and is preferably 5% by weight or less.
[0015]
It is preferable to remove as much as possible unreacted monomers, polymerization catalyst residues, and other impurities from the polymerized polymer. In addition, the degree of polymerization of the copolymer is such that the intrinsic viscosity [η] is 1.0 or more, particularly 1.4, in terms of stretchability when carbon fiber precursor fibers are spun and carbon fiber performance. The above is preferable. In general, those having an intrinsic viscosity [η] of 2.0 or less are used.
[0016]
The solvent for the spinning dope is a solvent that dissolves the acrylonitrile polymer, such as an organic solvent (for example, dimethylformamide, dimethylsulfoxide, dimethylacetamide), an inorganic solvent (for example, zinc chloride, rhodanate, nitric acid, etc.) ). Among them, it is particularly preferable to use dimethylacetamide.
[0017]
In order to obtain a dense coagulated yarn when spinning, it is preferable to use a mixed solution of a polymer and a solvent having a polymer concentration of a certain level or more as the spinning dope. The concentration of the acrylonitrile-based polymer is 17 % By weight, more preferably 19% by weight. In general, the polymer concentration is preferably 25% by weight or less.
[0018]
Further, the invention according to the present second aspect is characterized in that the temperature of the spinning solution in the outlet in the range of 50-65 ° C..
If the temperature of the spinning dope at the outlet is set in the range of 50 to 65 ° C., deterioration of the spinning dope due to heating can be prevented.
[0019]
The invention according to claim 3 is a method for producing an acrylonitrile fiber characterized by spinning the acrylonitrile-based spinning dope produced by the production method according to claim 1 or 2 .
In the spinning dope prepared by the above method, since the acrylonitrile polymer is uniformly and sufficiently dissolved in the solvent, troubles such as nozzle clogging and yarn breakage do not occur at the time of spinning efficiently. As the fiber is spun, fibers with small fineness are obtained. Further, the obtained acrylonitrile fiber has a uniform quality in the length direction and between the single fibers, and has sufficient strength.
[0020]
The invention according to claim 4 is a carbon fiber manufacturing method characterized by firing the acrylonitrile fiber manufactured by the manufacturing method according to claim 3 .
The acrylonitrile fiber obtained by the above production method is suitable as a precursor fiber for carbon fiber, and the carbon fiber produced using the fiber as a precursor fiber has high strength and high elasticity. It becomes.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a preferred example of a polymer solution production apparatus 1 applied to the present invention which is preferably used when producing an acrylonitrile-based spinning dope.
[0022]
The polymer solution manufacturing apparatus 1 has a cylindrical cylinder 2, and a cylindrical rotor 3 inside the cylinder 2 has its axis aligned with the axis of the cylinder 2 and can be rotated at high speed. It is stored in. In the center of the lower part of the cylinder 2, an introduction port 4 for supplying a mixture of the polymer sent from the metering pump P and its solvent into the cylinder 2 is formed. The outlet port 5 for the obtained polymer solution is formed.
[0023]
A gap 6 between the cylinder 2 and the rotor 3 constitutes a dissolution chamber 6 for the mixed solution of the polymer and the solvent. A large number of cylindrical pin members 7 project horizontally from the inner peripheral surface of the cylinder 2 in the radial direction of the cylinder 2. In addition, a large number of cylindrical pin members 8 are provided on the outer peripheral surface of the rotor 3 so as to protrude horizontally in the radial direction of the rotor 3 at positions that do not interfere with the pin member 7 of the cylinder 2.
[0024]
In the present embodiment, the pin members 7 and 8 are cylindrical, but may be prismatic with a polygonal cross section. However, in order to reduce the staying portion in the vicinity of the pin members 7 and 8, the pin member 7
, 8 are preferably circular. In FIG. 1, the pin members 7 and 8 have a uniform cross-sectional area in the protruding direction. However, the pin members 7 and 8 may have a weight shape that gradually decreases the cross-sectional area in the protruding direction.
[0025]
Further, in this embodiment, the pin members 7 and 8 arranged on the same circumference are projected in a radial direction with respect to a plane including the circumference, but have a desired angle with the circumferential direction. Can be made to project diagonally. Moreover, although the said pin members 7 and 8 are projected horizontally, both the pin members 7 and 8 can also be inclined and projected in the same diagonally upward or downward direction so as not to interfere with each other.
[0026]
Furthermore, the inside of the peripheral wall portion of the cylinder 2 is a flow path 2a for heating / cooling fluid, and a flow path 3a for heating / cooling fluid is also formed inside the rotor 3, and the dissolution The peripheral wall surface constituting the chamber 6 can be controlled to a desired temperature.
[0027]
A mixed solution of the polymer and its solvent, which is quantitatively supplied from the introduction port 4 of the polymer solution manufacturing apparatus 1 by the metering pump P, is introduced into the dissolution chamber 6. The liquid mixture flows spirally upward in the dissolution chamber 6 and is led out from a lead-out port 5 formed in the upper part of the cylinder. In the dissolution chamber 6, the rotor 3 rotates, and the mixed liquid is stirred by the pin member 7 of the cylinder 2 and the pin member 8 of the rotor 3 so that the polymer is uniform with respect to the solvent. To be distributed. Further, the polymer is uniformly dissolved in the solvent by the shearing force between the pin members 7 and 8 and the heat generated therewith.
[0028]
Further, a fluid controlled to a predetermined temperature is supplied to each of the heating / cooling fluid flow paths 2a, 3a of the cylinder 2 and the rotor 3 at a predetermined flow rate, and the mixed liquid in the dissolution chamber 6 is supplied to a desired temperature. And the temperature of the polymer solution led out from the outlet 5 is controlled. For example, in the case of producing an acrylonitrile-based spinning dope, the temperature of the undiluted solution led out from the outlet 5 is a temperature at which gelation is difficult, specifically in the range of 50 to 65 ° C, preferably 55 to 65 ° C. Control to range.
[0029]
Although the circumferential speed of the rotor 3 depends on the residence time of the mixed solution in the dissolution chamber 6, the shaft rotation speed is set to 10 m / s or less in order to suppress excessive heat generation due to the shearing force. Is appropriate. In addition, when it is desired to gradually increase or decrease the shearing force acting on the mixed liquid moving in the dissolution chamber 6, the cylinder 2 and the rotor 3 are conical and the peripheral speed of the rotor 3 can be increased or decreased. it can.
[0030]
In order to give shear force and heat necessary for dispersion / dissolution to the mixed solution of the polymer and its solvent, the gap between the dissolution chambers 6, that is, the inner peripheral surface of the cylinder 2 and the rotor 3 The distance from the outer peripheral surface is preferably 5 to 50 mm, the distance between the pin members 7 and 8 in the melting chamber 6 is 2 to 50 mm, and the protruding length of the pin members 7 and 8 is the gap between the melting chambers 6. It is preferable to set it as 50 to 90%.
[0031]
In the polymer solution manufacturing apparatus shown in FIG. 1, the rotor 3 is coaxially accommodated in the cylinder 2, but the axes of the cylinder 2 and the rotor 3 are shifted from each other so that the rotor 3 is placed in the cylinder 2. Can be stored. Furthermore, the rotor 3 can be rotated about the axis of the rotor 3 and the axis can be rotated along a circular locus centering on the axis of the cylinder 2.
[0032]
Hereinafter, the present invention will be described with specific examples and comparative examples. Various tests in the following examples and comparative examples are as follows.
(B) “Filtration pressurization test”
The amount of undissolved matter and gel components in the spinning dope is filtered through a 300 μm filter, then 5
Quantitative filtration was performed using a μm filter, and measurement was performed using a differential pressure before and after filtration using a 5 μm filter.
(B) “Falling ball speed”
The spinning dope was kept at 85 ° C. and 30 ° C. for 30 days, respectively, and then a steel ball having a diameter of 6.4 mm was put into the spinning dope and the falling speed of the steel ball was measured.
Measuring distance: 100mm
(C) “Strand strength of carbon fiber”
It measured according to the method of JIS-7601.
[0033]
"Example 1"
A mixed liquid (polymer concentration 21.2%, temperature 10 ° C.) of an acrylonitrile-based polymer copolymerized with acrylonitrile 96.6%, methacrylic acid 0.8%, and acrylamide 2.6%. A fixed amount pump was used to supply a fixed amount to the polymer solution production apparatus shown in FIG. 1, and the polymer was dissolved in the solvent. The gap of the dissolution chamber 6 of the polymer solution manufacturing apparatus is 15 mm, the pin member having a diameter of 10 mm and a protruding length of 10 mm is arranged in five rows and three stages on the rotor outer peripheral surface and five rows and four stages on the cylinder inner peripheral surface. Arranged. The peripheral speed of the rotor 3 is 4.4 m / s, the residence time of the mixed solution in the dissolution chamber 6 is set to 6 minutes, and the melting process is performed by the manufacturing apparatus. The temperature of the polymer solution at the outlet 5 is 65. A clear spinning stock solution at 0 ° C. was obtained.
[0034]
This spinning solution was discharged into a dimethylacetamide aqueous solution having a concentration of 67% and a temperature of 38 ° C. using a die having a pore diameter of 0.075 mm and a number of 3000 to obtain a coagulated yarn. Further, this coagulated yarn was washed and solvent-removed while being drawn, then an oil agent was applied, dried and densified, and further drawn in water vapor to obtain a precursor fiber having a single yarn fineness of 1.2 dtex.
This precursor fiber was made flame resistant at a temperature of 225 ° C. to 260 ° C., and subsequently carbonized at a maximum temperature of 1300 ° C. in a nitrogen atmosphere to obtain a carbon fiber strand.
[0035]
Table 1 shows the filtration pressure increase test, gelation test result, and carbon fiber strand strength of the spinning dope.
[0036]
"Comparative Example 1"
The same polymer and solvent mixture as in the example was dissolved using a conventional double tube heat exchanger with a residence time in the heat exchanger of 6.8 minutes and a heat medium temperature of 110 ° C. As a result, a spinning dope was obtained in which the temperature of the polymer solution at the outlet of the heat exchanger was 80 ° C. For this spinning dope, a precursor fiber having a single yarn fineness of 1.2 dtex was obtained by the same method as in the example. Furthermore, it baked like the Example and obtained the carbon fiber strand.
[0037]
Table 1 shows the filtration pressurization test, gelation test results, and carbon fiber strand strength of the spinning dope according to this comparative example.
[0038]
[Table 1]

[0039]
As is clear from the examples and comparative examples described above, according to the present invention, carbon that can be uniformly dissolved at a low temperature, and therefore can easily exhibit high strength and high elastic modulus even when made into carbon fibers. The acrylonitrile-based spinning dope for fibers can be produced by a method excellent in economic efficiency.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a front view of a polymer solution production apparatus according to a preferred embodiment of the present invention, with a half section cut away.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polymer solution manufacturing apparatus 2 Cylinder 2a Heating / cooling fluid flow path 3 Rotor 3a Heating / cooling fluid flow path 4 Inlet 5 Outlet 6 Dissolving chamber 7 Pin member 8 (outer peripheral surface of rotor) Surface) pin member P metering pump

Claims (4)

A cylinder provided with an inlet for introducing a mixture of a fixed amount of polymer and its solvent, and a lead-out port for deriving the produced polymer solution; and a columnar rotor rotatably disposed in the cylinder; And a polymer melting chamber having a gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the rotor of 5 to 50 mm, and a large number of pin members project from the inner peripheral surface of the cylinder. And a plurality of pin members having a spacing of 2 to 50 mm protruding from the outer peripheral surface of the rotor so as not to interfere with the pin member of the cylinder. The introduction port is formed in the lower part of the cylinder and the outlet port is formed in the upper part of the cylinder, and the melting chamber is heated in at least one of the cylinder and the rotor.・ To cool The apparatus for manufacturing a polymer solution comprising a heating and cooling means, and dispensing a mixture of acrylonitrile polymer and solvent, by rotating the rotor, the uniform dispersion and shear the mixture A method for producing an acrylonitrile-based spinning dope characterized in that it is uniformly dissolved by the accompanying heat generation. The method for producing an acrylonitrile-based spinning dope according to claim 1, wherein the temperature of the spinning dope at the outlet is set in a range of 50 to 65 ° C. A method for producing an acrylonitrile fiber, comprising spinning the acrylonitrile spinning stock solution produced by the production method according to claim 1 or 2 . A method for producing a carbon fiber, comprising calcining an acrylonitrile-based fiber produced by the production method according to claim 3 .

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