JP2017172081A - Method for producing acrylonitrile-based fiber bundle and method for producing carbon fiber bundle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which can stably produce a high-quality acrylonitrile-based fiber bundle while increasing a filament running velocity or increasing the number of holes in a spinneret, in dry-wet spinning.SOLUTION: In a method for producing an acrylonitrile-based fiber bundle, a spinning dope is once extruded from a spinneret into air, and is then introduced downward into a coagulation bath to which a coagulation bath liquid is supplied upward from a coagulation bath liquid inflow port disposed in a bottom surface, thereby forming coagulated filaments. The coagulated filaments are turned up at a direction changing guide disposed in the coagulation bath below the spinneret, and are drawn out to the outside of the coagulation bath. 60% or more of the flow directions of the coagulation bath liquid at respective positions which are 35 mm apart from a spinneret outer circumferential part, and which equally make at least 10 divisions in a circumference direction equally apart from a spinneret center, at a depth of 40 mm from a coagulation bath liquid surface, are directions toward the spinneret. The average of the absolute values of the flow velocities of the coagulation bath liquid is 0.8 m/min or higher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a stable and high-quality acrylonitrile fiber bundle suitable for a method for producing a carbon fiber bundle.

  In the manufacture of acrylonitrile fiber bundles used as carbon fiber precursor fibers, it is important to increase production efficiency and reduce manufacturing costs. To meet this demand, a wide variety of methods are used, such as a spinneret with an increased number of holes per spindle, a method of increasing the number of spindles and yarns, and a method of increasing the yarn running speed. Has been. Of these methods, increasing the number of holes per die and increasing the yarn traveling speed has a great advantage in that it can meet the demand without significant capital investment. .

  However, in the production of acrylonitrile fiber bundles, the spinning stock solution containing the acrylonitrile polymer is once extruded into the air from the die surface, then discharged downward into the coagulation bath, folded back with a direction change guide, and drawn out of the coagulation bath. When the dry and wet spinning method is employed, if the yarn traveling speed in the coagulation bath is increased, the quality of the resulting acrylonitrile fiber bundle is remarkably deteriorated, often accompanied by deterioration of operability such as yarn breakage.

  Therefore, in Patent Document 1, in the wet spinning method in which the spinning solution is directly discharged into the coagulation bath and drawn out of the coagulation bath, a partition plate is disposed between the spun yarn and the bottom of the coagulation bath, so that the yarn traveling speed is increased. A technique for suppressing disturbance of the yarn in the coagulation bath and disturbance of the coagulation bath liquid that causes entanglement even if the height is increased is disclosed. Similarly, in the wet spinning method, it is also known that the same effect is exhibited by a technique of arranging a current plate having an opening between the spun yarn and the bottom of the coagulation bath (see Patent Document 2).

  However, these techniques have a great effect in the wet spinning method. However, in the dry and wet spinning method, the solidification can be achieved simply by placing a partition plate or a current plate between the spun yarn and the bottom of the coagulation bath. Until now, it has been impossible to sufficiently suppress the disturbance of the bath liquid. The reason for this is that in order to keep the composition of the coagulation bath constant, the liquid once drained from the tank is circulated back to the tank. In the wet spinning method, the coagulation bath is generally supplied to the tank. The inflow direction of the bath liquid is the same as the direction in which the spinning dope is discharged. However, if the coagulation bath liquid is allowed to flow in the direction in which the spinning dope is discharged (downward) and in the horizontal direction by the dry and wet spinning method, the yarn is disturbed, and single fiber breakage and entanglement are induced. Therefore, in the dry-wet spinning method, the coagulation bath liquid is generally supplied from the coagulation bath liquid inlet 6 at the bottom of the coagulation bath using the circulation pump 8 as shown in FIG. Opposite (upward). Liquid generated by collision of the coagulation bath liquid supplied from below the coagulation bath for circulation and the flow of liquid accompanying the discharge yarn traveling downward, the so-called accompanying flow, in the bath Since the yarn receives the turbulence of the yarn and the flow of the bath liquid that has been changed by colliding with the tank wall on the coagulation bath exit side, it is a barrier to increasing the yarn running speed by inducing single fiber breakage or entanglement of the yarn (See Patent Document 4).

  In order to solve the above-mentioned problems, a technique is proposed in which a straightening tube is installed so as to surround the yarn with a moderate distance from the yarn running downward between the base and the direction change guide in the coagulation bath. (See Patent Document 3). However, in such a technique, the yarn before entering the flow straightening tube and the yarn that has come out are subjected to the disturbance of the bath liquid, so that the above-described problem is insufficient. Moreover, in order to control the accompanying flow of the thread | yarn which came out of the rectification | straightening cylinder, the technique which installs the partition plate along the flow of a thread | yarn is proposed (refer patent document 4). However, in such a technology, the current is supplied to the base around the current plate, so when the yarn traveling speed is increased, the flow supplied to the vicinity of the base becomes stronger, and the flow of the bath liquid near the base is disturbed. Yarn defects such as fiber breakage and adhesion between single fibers occur, which is insufficient to solve the above problems.

  Also, in order to make the yarn spun downward from the base less susceptible to the accompanying flow reflected from the bottom of the coagulation bath, the lateral rectification surrounding all or part of the periphery of the yarn spun downward from the base A technique for installing a plate has been proposed (see Patent Document 5). However, even if this technique is effective in suppressing the fluctuation of the coagulation liquid level, the direction change guide at the bottom of the horizontal rectifying plate is subjected to the disturbance of the bath liquid. The bath is changed in the direction (upward) toward the base position by colliding with the accompanying flow and the tank wall by increasing the yarn running speed or making the base multi-holes because the traveling direction is changed. When the liquid flow became stronger, the running yarn was greatly disturbed by the direction change guide, causing yarn defects such as single fiber breakage and adhesion between single fibers.

  In addition, in order to increase the production efficiency of the acrylonitrile fiber bundle, the outer surface of the base provided with a large number of spinning holes for discharging the spinning raw liquid is arranged at intervals to face the liquid surface of the coagulation liquid via the gas phase. In the dry-wet spinning spinning pack, a dry-wet spinning spinning pack having 6,000 or more spinning holes has been proposed (see Patent Document 6). However, the number of filaments in the discharged yarn increases due to the increase in the number of holes in the die, and the accompanying flow of the discharged yarn that progresses downward increases accordingly. The increased accompanying flow disturbs the bath liquid flow in the vicinity of the die, causing yarn defects such as single fiber breakage and single fiber bonding. Therefore, the effect of improving production efficiency was insufficient.

  In the dry and wet spinning method, it is necessary to stably produce a high-quality acrylonitrile fiber bundle while increasing the yarn running speed or increasing the number of holes in the die, and specifically, to what extent the flow of the bath liquid needs to be suppressed. No quantitatively evaluated method was disclosed.

  In addition, as a means for improving production efficiency, a technique using a PAN polymer solution having a specific molecular weight distribution is proposed (see Patent Document 7). However, the acrylonitrile fiber bundle obtained by such a technique is caused by the running yarn being disturbed by the direction change guide if it is continuously produced even if the quality and processability are stable in the short term. The single fiber breakage and the inter-single fiber adhesion that occurred became a yarn defect, and the yarn breakage occurred in the subsequent drawing process.

JP-A-62-33814 Japanese Patent Laid-Open No. 11-229227 JP-A-11-350244 JP 2007-291594 A International Publication No. 2013/047437 JP 2011-63926 A JP 2010-255159 A

  An object of the present invention is to provide a method capable of stably producing a high-quality acrylonitrile fiber bundle while increasing the yarn running speed or making the die porous in dry-wet spinning.

  In order to achieve the object, the method for producing an acrylonitrile fiber bundle of the present invention has the following configuration. That is, the spinning dope is once extruded into the air from the die, and then entered downward into the coagulation bath supplied with the coagulation bath liquid from the coagulation bath liquid inlet disposed on the bottom surface to form a coagulated yarn, A method for producing an acrylonitrile fiber bundle that is folded back by a direction changing guide disposed in a coagulation bath below the die and pulled out of the coagulation bath, the position being 35 mm away from the outer periphery of the die, the center of the die 60% or more of the direction of flow of the coagulation bath liquid at a depth of 40 mm from the coagulation bath liquid level at each of the positions equally divided in the circumferential direction from to the circumferential direction is the cap direction, and the absolute value of the flow rate of the coagulation bath liquid Is an acrylonitrile-based fiber bundle manufacturing method, characterized in that the average is 0.8 m / min or more.

  Moreover, the manufacturing method of the carbon fiber bundle of this invention, after manufacturing an acrylonitrile fiber bundle by the manufacturing method of the said acrylonitrile fiber bundle, flame-proofing in 200-300 degreeC oxidizing atmosphere, and then 1000 degreeC or more It is a manufacturing method of the carbon fiber bundle heated in an inert atmosphere.

  According to the present invention, in the dry and wet spinning method, even if the yarn traveling speed is increased or the die is made porous, the bath fluid resistance that the discharged yarn receives in the coagulation bath can be reduced, and thereby the single fiber Degradation factors such as breakage and entanglement can be reduced, and high-quality acrylonitrile-based carbon fiber bundles can be produced in large quantities in a short time. In particular, it is suitable for producing an acrylonitrile-based precursor fiber bundle for carbon fibers.

It is a sectional side view which shows an example of embodiment of the conventional dry-wet spinning apparatus roughly. It is a sectional side view which shows an example of embodiment of the dry-wet spinning apparatus which concerns on this invention. It is a top view which shows an example of embodiment of the dry-wet spinning apparatus which concerns on this invention. It is a sectional side view which shows another example of embodiment of the dry-wet spinning apparatus which concerns on this invention. It is a sectional side view which shows another example of embodiment of the dry-wet spinning apparatus which concerns on this invention. It is a sectional side view which shows another example of embodiment of the dry-wet spinning apparatus which concerns on this invention. It is a sectional side view which shows the dry-wet spinning apparatus which concerns on a comparative example. It is a top view which shows the dry-wet spinning apparatus which concerns on a comparative example. It is a sectional side view which shows the measuring method of the direction and flow velocity of the coagulation bath liquid of a dry-wet spinning apparatus. It is a top view which shows the measuring method of the direction and flow rate of the coagulation bath liquid of a dry-wet spinning apparatus.

  The present invention optimizes the flow of the coagulation bath liquid flow in the vicinity of the die in the direction of the die when the polymer discharged from the die enters the coagulation bath in order to obtain a stable and high-quality acrylonitrile fiber bundle. The purpose is to suppress inter-single fiber adhesion, single fiber entanglement, and further, single fiber breakage, which are caused by yarn swaying due to bath liquid disturbance.

  The present invention will be described in detail below.

  In the present invention, the spinning dope used as a raw material for the acrylonitrile fiber bundle is obtained by dissolving an acrylonitrile polymer in a solvent. As the acrylonitrile polymer, a polymer obtained by polymerizing 90% by mass or more of acrylonitrile (hereinafter abbreviated as AN) is preferably used. The acrylonitrile polymer may be a homopolymer obtained by polymerizing 100% by mass of AN, or a copolymer obtained by copolymerizing AN with another monomer. Examples of the monomer copolymerized with AN include acrylic acid, methacrylic acid, itaconic acid, and alkali metal salts thereof, ammonium salts and lower alkyl esters, acrylamide and derivatives thereof, allyl sulfonic acid, methallyl sulfonic acid, and their Salts or alkyl esters can be employed.

  As the solvent used for the spinning dope, for example, an aqueous zinc chloride solution, dimethylacetamide, dimethylsulfoxide (hereinafter abbreviated as DMSO), dimethylformamide, or the like can be used. The concentration of the acrylonitrile polymer in the spinning dope is preferably 10% by mass or more and 30% by mass or less. If the concentration is too low, the single fibers of the coagulated yarn discharged into the coagulation bath are likely to be cut by rubbing with the roller. If the concentration is too high, the pressure in the die increases and the discharge holes are clogged with the polymer. Easy to operate and may deteriorate.

  Hereinafter, the present invention will be described with reference to the drawings. 2 and 3 are a side sectional view and a top view of a dry / wet spinning apparatus for illustrating one embodiment of the present invention.

  In the present invention, the spinning stock solution, which has been adjusted to a temperature of 25 to 30 ° C., preferably 27 to 29 ° C., is once extruded into the air from the die 1 and directed downward into the coagulation bath 3 where the coagulation bath solution is stored. Let's enter. Here, as the coagulation bath liquid, a mixed liquid of a solvent and water of the same type as the solvent used for the spinning dope can be preferably used. If the spinning dope temperature is too low, the viscosity of the spinning dope is too high, the free discharge linear velocity from the die 1 is too slow, and single fiber breakage may occur between the die 1 and the coagulation bath liquid surface 7. is there. On the other hand, if the temperature of the spinning dope is too high, the viscosity of the spinning dope is too low, which may cause a decrease in operability due to the fusion of single fibers between the die 1 and the coagulation bath liquid surface 7.

  The coagulated yarn 2 that has entered the coagulation bath 3 is folded back by a direction changing guide 4 disposed in the coagulation bath 3 below the base 1 and is moved out of the coagulation bath through the coagulation bath discharge free roller 5. Pulled out. In FIG. 2, the circulating coagulation bath liquid is supplied upward from a coagulation bath liquid inlet 6 located below the direction change guide 4. The accompanying flow of the coagulated yarn 2 collides with the bottom surface of the coagulation bath 3 below the direction changing guide 4 and changes in the direction of the base 1 (upward).

  Here, the accompanying flow increases as the number of holes in the die 1 increases or the spinning speed increases, and the flow of the coagulation bath liquid immediately below the die 1 becomes a complicated turbulent flow due to the accompanying flow. An object of the present invention is to rectify the accompanying turbulence. However, since the circulating coagulation bath liquid controls the temperature and concentration in the coagulation bath 3 to predetermined values, the circulation rate of the coagulating bath liquid circulates only by the required amount as the number of holes in the die 1 increases or the spinning speed increases. It is preferable to adopt a form.

  In the present invention, the flow of the coagulation bath liquid just below the base 1 is rectified, thereby reducing quality deterioration factors such as single fiber breakage and entanglement, so that the position is 35 mm away from the outer periphery of the base 1. 60% or more of the flowing direction of the coagulation bath liquid at a depth of 40 mm from the coagulation bath liquid surface 7 at each of the positions equally divided at least 10 in the circumferential direction from the center of the base 1 is the direction of the base 1. It is an essential condition, preferably 80% or more, more preferably 90% or more. If less than 60% of the flow of coagulation bath liquid is directed to the base 1, the flow of the coagulation bath liquid just below the base 1 becomes turbulent, causing bonding between single fibers or entanglement of single fibers, Yarn defects such as fiber breakage occur. Moreover, there is no restriction | limiting in the nozzle hole arrangement | positioning used for this invention, The shape which has a side in a part of nozzle hole outer peripheral parts, such as circular, a polygon, and a semicircle shape, and a cyclic | annular nozzle | cap | die.

  Moreover, from the point which suppresses the fall of production efficiency, it is a position 35 mm away from the outer peripheral part of the nozzle | cap | die 1, Comprising: From the coagulation bath liquid surface in each position divided | segmented at least 10 from the center of the nozzle | cap | die 1 in the circumferential direction The average absolute value of the flow rate of the coagulation bath liquid at a depth of 40 mm is an essential condition of 0.8 m / min or more, preferably 1.0 m / min or more.

  Here, the direction of the flow of the coagulation bath liquid at a depth of 40 mm from the coagulation bath liquid surface at each of the positions 35 mm away from the outer periphery of the base and equally divided into at least 10 in the circumferential direction from the center of the base The average absolute value of the flow velocity is obtained as follows.

  As shown in FIGS. 9 and 10, beads 10 having a specific gravity equal to that of the coagulation bath liquid are divided into at least 10 parts from the center of the die evenly in the circumferential direction at a depth of 40 mm from the coagulation bath liquid surface 7, more specifically in the flow direction. In order to ascertain the distribution of the bead, it is preferably arranged one by one at a position 35 mm away from the outer periphery of the die on a straight line in a radial direction of 20 divisions or more, and the movement of the beads 10 is directed from the air in the liquid surface direction. Then, observe the movement of the beads 10.

  The moving distance of the beads is calculated by simultaneously photographing a measure or the like with a camera and analyzing the image. In order to prevent the running state of the coagulated yarn from being different depending on whether or not the beads 10 are present, the beads have an outer diameter of 2 mm.

  At each measurement point, images were taken three times immediately before placing the beads and 0.5 seconds after placing, and the images immediately before placing and 0.5 seconds after placing were superimposed, before and after the movement of the beads in the average of three measurements. If there is an outer periphery of the base on the straight line connecting the positions, it is determined that the head is facing the base. Moreover, the distance which connected the position of the bead before and behind a movement is made into a movement distance, and let the average value for 3 times measurement be Dmm. From the average value D of the moving distance, the flow rate Vm / min of the coagulation bath liquid is calculated by the formula V = D / 8.33. Moreover, the average of the absolute value of the flow velocity V is calculated from the flow velocity V of the coagulation bath liquid at each measurement point, and is defined as the average of the absolute values of the flow velocity of the coagulation bath liquid.

  More than 60% of the direction of the coagulation bath liquid flowing at a depth of 40 mm from the coagulation bath liquid level at each position at a distance of 35 mm from the outer periphery of the base and equally divided in the circumferential direction from the center of the base by at least 10% Is not particularly limited as a means for setting the average of the absolute values of the flow rate of the coagulation bath liquid to 0.8 m / min or more. For example, as shown in FIG. The coagulating liquid is sucked up from the coagulating yarn outlet side and is coagulated in the coagulating bath 3 immediately below the base 1 so that the coagulated thread runs downward from the periphery of the base 1 toward the direction change guide 4. Means for forcibly rectifying the accompanying flow directly under the base 1 or in the coagulation bath 3 directly under the base 1 as in the case of the forced liquid pump 9, which has electric solvent resistance. Install a propeller and solidify around the base 1 Article By is feeding a coagulation liquid so as to be perpendicular to the direction of travel downward in the direction of the diverting guide 4, include means for forcibly rectified the accompanying flow just below the die 1. The forced liquid feed pump 9 can easily adjust the flow rate according to the valve opening, and can be easily implemented. By increasing the amount of liquid fed from the forced liquid feeding pump 9 in accordance with the increase in the number of nozzle holes and the increase in spinning speed, the flow of the coagulation bath liquid directly under the nozzle 1 can be controlled.

  If the number of holes in the die is increased, the yarn density of the coagulated yarn in the coagulation bath is increased, and yarn defects such as inter-single fiber adhesion and inter-single fiber entanglement tend to occur. Therefore, the acrylonitrile fiber of the present invention In the bundle manufacturing method, the number of holes in the die is preferably 60,000 or less, and more preferably 24,000 or less. Moreover, from the point which suppresses the fall of production efficiency, it is preferable to set it as 1,000 or more holes, More preferably, it is 3,000 or more, More preferably, it is 6,000 or more.

  From the viewpoint of suppressing disturbance of the coagulation bath liquid due to the coagulated yarn 2 and suppressing disturbance of the coagulation bath liquid due to the circulating bath liquid, it is preferable to have the rectifying cylinder 12 and the partition plate 11 as shown in FIG. The flow straightening cylinder 12 is provided around the solidified yarn 2 between the base 1 and the direction changing guide 4 and is processed into a circular shape, a rectangular shape, a polygonal shape or the like according to the shape of the base 1 to be used. The speed can be improved. The rectifying cylinder 12 has an upper end position of preferably 0 to 300 mm downward from the coagulation bath liquid surface 7, and more preferably 50 to 150 mm. If the rectifying cylinder 12 protrudes above the coagulation bath liquid surface 7, there is a concern that the circulation of the coagulation bath liquid is hindered and density spots are generated. Further, the partition plate 11 can be provided along the traveling direction of the solidified yarn 2 from the traveling position of the solidified yarn 2 toward the side surface and the bottom surface of the coagulation bath 3. It is preferable that the portion is located at a depth of 0 to 300 mm from the coagulation bath liquid level 7. Moreover, in order not to give the disturbance of the coagulation bath liquid to the coagulated yarn 2 as much as possible, the distance between the coagulated yarn 2 and the partition plate 11 is preferably 20 to 200 mm, and more preferably 50 to 100 mm. . Further, it is more preferable to install the partition plate 11 so as to surround the coagulated yarn 2 at a distance of 50 to 100 mm or to sandwich the coagulated yarn 2.

  The fiber is spun by a dry and wet spinning method, and the coagulated yarn is drawn out of the coagulation bath and then stretched in the bath. This stretching in the bath is usually stretched about 2 to 6 times in a stretching bath at 50 to 98 ° C. The spun coagulated yarn is preferably washed with water after stretching in a bath or drawn in a bath after washing with water to remove the residual solvent. After stretching in the bath, an oil agent is usually applied and dried and densified with a hot roller or the like. If necessary, secondary stretching such as steam stretching is performed thereafter. In the present invention, whether a plurality of acrylonitrile fiber bundles obtained through these steps are wound or combined with a free roller guide group for bundling before being stored in a can and wound on a package by a winder Stored in a can. As another aspect, a plurality of wound acrylonitrile fiber bundles can be unwound or pulled out from the can and combined with a free roller guide group for focusing. When the number of single yarns constituting the acrylonitrile fiber bundle exceeds 1,000, and more preferably exceeds 2,000, the effect of the method for producing an acrylonitrile fiber bundle of the present invention can be suitably obtained. The upper limit of the number of single yarns is not particularly limited, but is usually 100,000 or less.

  Next, a method for producing a carbon fiber bundle from an acrylonitrile fiber bundle obtained by the method for producing an acrylonitrile fiber bundle of the present invention will be described.

  The acrylonitrile fiber bundle produced by the method for producing an acrylonitrile fiber bundle is subjected to a flameproofing treatment in an oxidizing atmosphere such as air at 200 to 300 ° C. It is preferable to increase the treatment temperature in a plurality of stages from low temperature to high temperature in order to obtain a flame-resistant fiber bundle, and it is more suitable for carbon fiber to stretch the fiber bundle at a high stretch ratio without causing fluff generation. It is preferable for sufficiently expressing the performance. Subsequently, the obtained flame-resistant fiber bundle is heated to 1000 ° C. or higher in an inert atmosphere such as nitrogen to produce carbon fibers. Thereafter, by performing anodization in an aqueous electrolyte solution, it is possible to impart a functional group to the surface of the carbon fiber and enhance the adhesion to the resin. Moreover, it is preferable to provide a sizing agent such as an epoxy resin to obtain carbon fibers having excellent scratch resistance.

  Next, based on an Example, this invention is demonstrated concretely.

(Adhesion evaluation)
The fiber bundle after taking out from the coagulation bath was sampled 50 cm, the fiber bundle was swimmed with a vat with black bottom and 2 cm depth of water, and the degree of adhesion was observed to evaluate the adhesion state. The evaluation criteria are as follows.
1: Dispersed into a single fiber.
2: When tapping the fiber bundle in water with tweezers, it breaks into single fibers.
3: Including a fiber bundle that does not disperse in units of several.
4: Contains one fiber bundle that does not disperse in units of several tens.
5: Contains a plurality of fiber bundles that cannot be separated in units of several tens.

(Quality of acrylonitrile fiber bundle)
Before winding up the acrylonitrile fiber bundle, the number of fluff of acrylonitrile fiber for 1000 m was counted, and the quality was evaluated. The evaluation criteria are as follows.
1: (number of fuzz / one fiber bundle / 1000 m) ≦ 1
2: 1 <(number of fuzz / 1 fiber bundle / 1000 m) ≦ 2
3: 2 <(number of fuzz / 1 fiber bundle · 1000 m) ≦ 5
4: 5 <(number of fuzz / 1 fiber bundle / 1000 m) <60
5: (number of fuzz / 1 fiber bundle / 1000 m) ≧ 60
(Comparative Example 1)
While using the dry and wet spinning apparatus shown in FIGS. 1 and 8, as the spinning dope, a DMSO solution containing 20% by mass of AN copolymer obtained by copolymerizing AN 99 mol% and itaconic acid 1 mol% is used as the spinning dope. The spinning dope, temperature-controlled at 28 ° C., was once extruded into air from a die having a number of holes of 6,000 holes per spindle and allowed to enter downward into a coagulation bath adjusted with a 30% by mass DMSO aqueous solution. After turning back at an angle of 65 ° with the direction change guide 4 and drawing out at 25 m / min out of the coagulation bath, it was carried into the water washing step. Then, the oil agent which has amino silicone as a main component was provided, making it extend | stretch in a bath extending process, and also the acrylonitrile-type fiber bundle was obtained through the drying and post-drawing process.

  At this time, it is 57 mm in the direction in which the coagulation bath liquid flows at a depth of 40 mm from the coagulation bath liquid surface 7 at a position that is 35 mm away from the outer periphery of the base and is equally divided into 14 in the circumferential direction from the center of the base. %Met. The quality at the time of adhesion and acrylonitrile fiber production was not satisfactory.

Example 1
3 and 6, the depth from the coagulation bath liquid surface 7 at a position 35 mm away from the outer periphery of the die and 14 equally divided from the center of the die in the circumferential direction. The coagulation bath liquid is fed from the position of the coagulation bath liquid surface 7 to a depth of 40 mm from the position of the coagulation bath liquid surface 7 at a position 50 mm away from the outer periphery of the base so that 93% of the direction of flow of the coagulation bath liquid at 40 mm is directed toward the base. An acrylonitrile fiber bundle was obtained in the same manner as in Comparative Example 1 except that two forced liquid feeding pumps 9 were installed to adjust the liquid feeding amount. The quality during bonding and acrylonitrile fiber production was good.

(Example 2)
An acrylonitrile fiber bundle was obtained in the same manner as in Comparative Example 1 except that the dry and wet spinning apparatus shown in FIGS. At this time, 86 in the direction in which the coagulation bath liquid flows at a depth of 40 mm from the coagulation bath liquid surface 7 at a position that is 35 mm away from the outer periphery of the base and is equally divided into 14 in the circumferential direction from the center of the base. %Met. The quality at the time of adhesion and acrylonitrile fiber production was the same as in Example 1 and was satisfactory.

(Comparative Example 2)
An acrylonitrile fiber bundle was obtained in the same manner as in Comparative Example 1 except that the wet and wet spinning apparatus shown in FIGS. 1 and 8 was used and drawn out at 35 m / min out of the coagulation bath. At this time, it is 29 mm in the direction in which the coagulating bath liquid flows at a depth of 40 mm from the coagulating bath liquid level 7 at each of the positions 35 mm away from the outer periphery of the base and equally divided into 14 circumferentially from the center of the base %Met. The quality at the time of adhesion and acrylonitrile fiber production was worse than that of Comparative Example 1 and was not satisfactory.

(Example 3)
Using the dry and wet spinning apparatus shown in FIGS. 3 and 6, the position is drawn out at 35 m / min to the outside of the coagulation bath, and the position is 35 mm away from the outer periphery of the base and is equally divided into 14 in the circumferential direction from the center of the base. In the same manner as in Example 1, except that the liquid feed amount of the forced liquid feed pump 9 was adjusted so that 64% of the flow direction of the coagulation bath liquid at a depth of 40 mm from the coagulation bath liquid surface 7 was directed toward the die. A fiber bundle was obtained. There was no problem in the quality of adhesion and acrylonitrile fiber production. In addition, the production efficiency was improved in proportion to the speed of drawing out of the coagulation bath from 25 m / min in Example 2 to 35 m / min, and the manufacturing cost was satisfactory.

(Comparative Example 3)
An acrylonitrile fiber bundle was obtained in the same manner as in Comparative Example 2 except that the dry and wet spinning apparatus shown in FIGS. At this time, 50 in the direction in which the coagulating bath liquid flows at a depth of 40 mm from the coagulating bath liquid surface 7 at positions that are 35 mm away from the outer periphery of the base and equally divided into 14 in the circumferential direction from the center of the base. %Met. Although the quality at the time of adhesion and acrylonitrile fiber production was improved as compared with Comparative Example 2, it was still not satisfactory.

Example 4
While using the dry and wet spinning apparatus shown in FIGS. 2 and 3, the depth from the coagulating bath liquid surface 7 at a position 35 mm away from the outer periphery of the die and equally divided into 14 in the circumferential direction from the center of the die. An acrylonitrile fiber bundle was obtained in the same manner as in Example 3 except that the liquid feed amount of the forced liquid feed pump 9 was adjusted so that 79% of the coagulating bath liquid flow direction at 40 mm was directed toward the die. There was no problem in adhesion, and the quality when producing acrylonitrile fiber was improved as compared with Example 2. In addition, the production efficiency was improved in proportion to the speed of drawing out of the coagulation bath from 25 m / min in Example 1 to 35 m / min, and the manufacturing cost was satisfactory.

(Example 5)
3 and 4, the depth from the coagulation bath liquid surface 7 at a position 35 mm away from the outer periphery of the die and 14 equally divided from the center of the die in the circumferential direction. An acrylonitrile fiber bundle was obtained in the same manner as in Example 3 except that the liquid feed amount of the forced liquid feed pump 9 was adjusted so that 71% of the coagulating bath liquid flow direction at 40 mm was directed toward the die. Adhesion was improved as compared with Example 2, and there was no problem in the quality when acrylonitrile fiber was produced. In addition, the production efficiency was improved in proportion to the speed of drawing out of the coagulation bath from 25 m / min in Example 1 to 35 m / min, and the manufacturing cost was satisfactory.

(Example 6)
3 and 5, the depth from the coagulation bath liquid surface 7 at a position 35 mm away from the outer periphery of the die and 14 equally divided from the center of the die in the circumferential direction. An acrylonitrile fiber bundle was obtained in the same manner as in Example 3 except that the liquid feed amount of the forced liquid feed pump 9 was adjusted so that 86% of the coagulating bath liquid flow direction at 40 mm was directed toward the die. The quality at the time of adhesion and acrylonitrile fiber production was improved compared with Example 2 and was good. In addition, the production efficiency was improved in proportion to the speed of drawing out of the coagulation bath from 25 m / min in Example 1 to 35 m / min, and the manufacturing cost was satisfactory.

1 Coupling 2 Coagulated yarn 3 Coagulation bath 4 Direction change guide 5 Coagulation bath discharge free roller 6 Coagulation bath liquid inlet 7 Coagulation bath liquid level 8 Circulating pump 9 Forced liquid feeding pump 10 Beads 11 Partition plate 12 Rectifier cylinder

Claims (7)

  The spinning solution is once extruded from the die into the air, and then entered downward into the coagulation bath supplied with the coagulation bath solution from the coagulation bath solution inlet located on the bottom to form a coagulated yarn. A acrylonitrile fiber bundle manufacturing method for folding a coagulated yarn with a direction change guide arranged in the coagulation bath and drawing it out of the coagulation bath, at a position 35 mm away from the outer periphery of the die and from the center of the die 60% or more of the direction of flow of the coagulation bath liquid at a depth of 40 mm from the coagulation bath liquid surface in each of the positions equally divided into at least 10 in the circumferential direction is the die direction, and the average of the absolute values of the flow rates of the coagulation bath liquid Is a method for producing an acrylonitrile-based fiber bundle, which is 0.8 m / min or more.   The method for producing an acrylonitrile fiber bundle according to claim 1, wherein a speed at which the coagulated yarn is drawn out of the coagulation bath is 25 to 50 m / min.   The method for producing an acrylonitrile fiber bundle according to claim 1 or 2, wherein the number of holes in the die is 1,000 to 60,000.   The method for producing an acrylonitrile fiber bundle according to any one of claims 1 to 3, wherein means for controlling the flow of the coagulation bath liquid is provided in the coagulation bath so that the coagulation bath liquid flows in the direction of the die.   A partition plate having a shape along the running direction of the coagulated yarn is provided at a position 20 to 200 mm away from the running position of the coagulated yarn in the direction of the side and bottom of the coagulation bath, and the start and end portions of the partition plate are solidified. The method for producing an acrylonitrile fiber bundle according to any one of claims 1 to 4, which is located at a depth of 0 to 300 mm from the bath liquid surface.   The method for producing an acrylonitrile fiber bundle according to any one of claims 1 to 5, further comprising a flow straightening tube around a solidified yarn between the die and the direction changing guide. An acrylonitrile fiber bundle is produced by the method for producing an acrylonitrile fiber bundle according to any one of claims 1 to 6, followed by flameproofing in an oxidizing atmosphere at 200 to 300 ° C, and then inert at 1000 ° C or more. A method for producing a carbon fiber bundle heated in an atmosphere.

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