KR20200123776A - Fiber manufacturing method and carbon fiber manufacturing method - Google Patents

Abstract

In a method for producing a fiber in which a spinning dope obtained by dissolving a fiber-forming polymer in a solvent is discharged from a spinneret (1), once run in air, and then guided into a coagulation bath (3) and solidified. , The air volume (Af) per unit time of the gas phase part formed between the coagulation bath (3) liquid surface in a vertical downward direction from the discharge surface of the spinneret (1) is the gas phase volume (Vh) ) With respect to the amount of solvent (As) in the spinning dope per unit time, satisfying the relational expression of 0.0008m ³ ≤Af/(As/Vh) ≤0.0015m ³ , and 1 of the absolute humidity at 4 points in the outer periphery of the detention in the meteorological unit A method for producing fibers having a time average value of 20 g/m ³ or less, respectively. In dry and wet spinning, by suppressing the occurrence of condensation in the spinneret, reducing the quality due to winding on rollers in the subsequent process, fluff in the drawing process, and thread breakage As a whole, it provides a fiber manufacturing method that can greatly increase productivity and quality.

Description

Fiber manufacturing method and carbon fiber manufacturing method

In the present invention, when fibers are obtained by a dry-wet spinning method, condensation or water droplets are not generated on the surface of the spinneret, and the running property of the yarn is remarkably stabilized to obtain a fiber. It relates to a method of manufacturing a possible fiber.

In order to obtain fibers by spinning a fiber-forming polymer that is difficult to melt, such as polyacrylonitrile, a wet spinning method or a dry wet spinning method is employed. Among these, the dry-wet spinning method is a method in which a spinning dope obtained by dissolving a fiber-forming polymer in a solvent is discharged from a spinneret, once run in a gas, and immediately delivered to a coagulation bath to solidify. Compared to the spinning method, since the draft is relaxed in a gas without bath liquid resistance, spinning at high speed or high draft is possible, and thus, it is used for textile production for clothing or industrial use. In addition, since the dry-wet spinning method can make the fiber more dense, it has recently been utilized in the production of a precursor fiber of high-strength and high modulus carbon fiber, and the dry-wet spinning method is used to perform high-speed spinning or multi-hole spinneret to increase productivity. have.

Such a dry-wet spinning method extrudes the spinning dope from the spinneret installed outside the coagulation bath, so that a gas phase part exists between the spinneret surface and the coagulation bath, and high-speed spinning or increasing the number of holes in one spinneret, When performing so-called polyholeization, the vapor of the solvent constituting the spinning dope increases in the gas phase part, and this vapor stays in the gas phase part, and condensation tends to occur on the spinneret face. The condensed droplets block the ejection holes of the spinneret and become imprisoned due to adhesion of fibers, non-uniformity in fineness, single yarn breakage, and droplets coming into contact with the coagulation surface. It causes fluff and thread breakage in the roller winding and drawing process in the subsequent process, and the operability and quality are remarkably reduced. The above-described problem is particularly remarkable by performing high-speed spinning or multi-hole formation of a spinneret to increase productivity.

For the purpose of improving this problem, a method of preventing condensation by circulating gas from one direction in a spinneret in dry-wet spinning and a vapor phase part of a coagulation bath has been proposed (Patent Document 1).

In addition, even in multi-hole detentions exceeding 2,000 holes, the gaseous phase gas formed between the discharge surface of the spinneret and the coagulation bath is alternately sucked from the two directions between the discharge surfaces to prevent the retention of solvent vapor. A method of blocking is being studied (Patent Document 2).

In addition, in order to suppress condensation on the confinement surface by controlling the temperature and humidity around the confinement, a method of circulating air with adjusted temperature and humidity surrounding the coagulation chamber is also being studied (Patent Document 3).

Japanese Laid-Open Patent No. Hei 5-044104 Japanese Laid-Open Patent No. 2007-239170 Japanese Patent Laid-Open Publication No. 2010-236139

If the number of holes used in the spinneret is small, for example, about 300 holes, even with the technique proposed in Patent Document 1, condensation can be effectively suppressed, but with a number of 2,000 holes or more, the hole density is increased. In addition, in a condition in which vapor of the solvent tends to stay in the gaseous phase in which the height of the gaseous phase between the coagulation bath liquid level is less than 20 mm in a vertical downward direction from the spinneret discharge surface in dry and wet spinning, according to Patent Document 1 Even if the proposed technology is applied, there is a problem that the condensation cannot be eliminated because the airflow may drift and steam may stay.

In addition, with respect to Patent Document 2, when the pore density is high, there is a problem in that the suction of the gaseous phase is insufficient and the vapor of the solvent is agglomerated, and condensation proceeds on the surface that is not exhausted.

In Patent Document 3, controlled air was introduced into the discharge hole of the outer layer of the crest, but the controlled air did not reach the inside of the crest, and the effect was insufficient for suppressing condensation. In addition, in order to perform temperature-humidity control by surrounding the entire coagulation chamber, it was practically difficult to implement it because of the increase in equipment and equipment cost.

An object of the present invention is, for example, a condition in which a hole density of 2,000 holes or more is high, and a height of a gaseous part formed between the coagulation bath liquid level in a vertical downward direction from the spinneret discharge surface in dry and wet spinning is less than 20 mm In addition, fiber that suppresses the occurrence of condensation in the spinneret, improves the deterioration of quality due to roller winding in the subsequent process, fluff in the drawing process, and thread breakage, thereby greatly enhancing productivity and quality overall. It is to provide a manufacturing method of.

In order to solve the said subject, the fiber manufacturing method of this invention has the following structure. In other words,

In a method for producing a fiber in which a spinning dope obtained by dissolving a fiber-forming polymer in a solvent is discharged from a spinneret, once run in air, and then guided in a coagulation bath to solidify, in a vertical downward direction from the discharge surface of the spinneret. The amount of air (Af) per unit time of the gaseous part formed between the surface of the coagulation bath liquid is 0.0008m ³ ≤Af/(As/Vh) with respect to the amount of solvent (As) in the spinning dope per unit time in the volume of the gaseous part (Vh) This is a method for producing fibers in which the relational expression of ≤0.0015m ³ is satisfied, and the average value of the absolute humidity at four points in the outer periphery of the detention in the meteorological unit is 20 g/m ³ or less, respectively.

Moreover, the carbon fiber manufacturing method of this invention has the following structure. In other words,

This is a method for producing a carbon fiber in which fibers are produced by the above-described fiber production method, then treated with flame resistance in an oxidizing atmosphere at 200 to 300°C, and then heated in an inert atmosphere at 1,000°C or higher.

In the fiber manufacturing method of the present invention, it is preferable that the relative standard deviation of the wind speed at the four points of the outer periphery of the imprisonment in the gaseous part is 40% or less.

In the fiber manufacturing method of the present invention, the number of holes in the spinneret is preferably 2,000 or more and 50,000 or less.

In the fiber production method of the present invention, it is preferable that the fiber-forming polymer is an acrylonitrile polymer.

According to the present invention, for example, even under conditions of dry and wet spinning in which the hole density of 2,000 holes or more is high, and the distance between the spinneret and the coagulation bath liquid is less than 20 mm, the occurrence of condensation in the spinneret is suppressed, and subsequent It is possible to improve the deterioration of quality due to roller winding in the process, fluff in the stretching process, and thread breakage, and overall productivity and quality can be greatly improved. In particular, it is preferable for producing an acrylonitrile-based precursor fiber for carbon fiber.

1 is a schematic top view and an example of a front view of a radiation area in the case where an air supply nozzle or an exhaust nozzle is provided in the present invention.

Hereinafter, the present invention will be described in more detail.

The method of the present invention can be used when producing acrylonitrile fiber for clothing, acrylonitrile fiber for carbon fiber, aromatic polyamide fiber, etc., but in particular, when producing acrylonitrile fiber for carbon fiber The effect is recognized most remarkably.

In the present invention, a spinning dope obtained by dissolving a fiber-forming polymer in a solvent is used. As the fiber-forming polymer, an acrylonitrile polymer, an aromatic polyamide, or the like can be used. As for the polymerization method for obtaining the polymer, solution polymerization, emulsion suspension polymerization, bulk polymerization, or the like is used, and may be a batch method or a continuous method.

As a solvent in which the polymer is dissolved, in the case of an acrylonitrile polymer, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), zinc chloride aqueous solution (ZnCl ₂ aq), sodium thiocyanate Although an aqueous solution (NaSCNaq) or the like can be used, in terms of productivity, in the dry-wet spinning method, DMSO, DMF or DMAc having a high coagulation rate of the polymer is preferred, and DMSO having a particularly fast coagulation rate is particularly preferred.

The spinning dope is discharged from the discharge surface of a spinneret installed on the coagulation bath through the gas phase, and solidified in the coagulation bath to form fibers.

Regarding the temperature of the spinning dope and the temperature of the coagulation bath, the condition in which the difference between the atmospheric temperature and the dew point of the gas phase formed between the coagulation bath liquid surface in a vertical downward direction from the discharge surface of the spinneret (atmosphere temperature-dew point) appears as large as possible. desirable.

As the temperature of the spinning dope, the lower the temperature is, the smaller the evaporation amount of the solvent is, so it is preferable that it is not less than the solidification point of the solvent used in the spinning dope. It is preferable that it is below °C. When the temperature of the spinning dope is within this preferred range, the viscosity of the spinning dope is appropriately maintained, the bag property is good, and the operation property is excellent. As the coagulation bath, usually an aqueous solution of the same solvent as the solvent used for the spinning dope is used, but in particular, since condensation is liable to occur in an organic solvent system, when an aqueous solution of DMSO, DMF, or DMAc is used as the coagulation bath, the present invention The effect of is remarkable. The upper limit of the temperature of the coagulation bath is preferably 20°C or less, more preferably 10°C or less, and even more preferably 7°C or less. When the upper limit of the temperature of the coagulation bath is within this preferred range, the occurrence of condensation can be effectively suppressed. The lower limit of the temperature of the coagulation bath is preferably 0°C or higher, and more preferably 1°C or higher. When the lower limit of the temperature of the coagulation bath is within this preferred range, the bag property is good and the operation property is excellent.

The number of holes of the spinneret is preferably 2,000 or more and 50,000 or less, and more preferably 4,000 or more and 20,000 or less. If the number of holes is within this preferred range, productivity is good, while the mass of the detention is not excessively large, it is easy to secure workability, and an increase in equipment cost can be prevented. 1 hole per detention occupied area (the number of spinneret holes ÷ area), it is preferable to use the one in a range from 5mm ² 10mm ^2. If the area occupied by the detention per hole is within this preferred range, productivity is good, while condensation occurs even when sufficient voids cannot be secured in the gas phase between the spinneret and the coagulation bath during dry-wet spinning. Can be effectively prevented.

In the present invention, the air volume (Af) per unit time of the gas phase part formed between the discharge surface of the spinneret and the coagulation bath liquid surface is 0.0008 with respect to the amount of solvent (As) in the spinning dope per unit time in the volume (Vh) of the gas phase part. m ³ ≤Af/(As/Vh)≤0.0015m ³ satisfies the relational expression, and the 1 hour average value of absolute humidity at 4 points (measurement points A to D) at the outer periphery of detention in the meteorological department is 20 g/m ³ or less, respectively. It is important.

For this, for example, a method of installing a blower of dehumidified air at a location separated from the spinneret to blow a certain amount of air to the gaseous phase, or installing an air supply nozzle or an exhaust nozzle around the detention center to simultaneously perform supply and exhaust. There are ways to change the direction of supply and exhaust over time.

In the present case, Af / (As / Vh) is more than 0.0008m ³ intended to 0.0015m to ³ or less, preferably ³ or more 0.0009m 0.0014m ³ or less, and more preferably less than 0.0010m ³ more than 0.0013m ³ . If it exceeds 0.0015 m ³ , the liquid level of the coagulation bath flows, resulting in unstable radioactivity, resulting in insufficient effect. Further, the average value of the absolute humidity at the four outer periphery points of the detention for one hour is preferably 20 g/m ³ or less, 15 g/m ³ or less, and more preferably 10 g/m ³ or less.

From the viewpoint of scavenging without unevenness in the wind speeds of the four outer circumferences of detention, the relative standard deviation of the wind speeds of the four outer circumferences of detention is preferably 40% or less, more preferably 20% or less, and even more preferably 10. % Or less. When the relative standard deviation of the wind speeds of the four outer circumferences of the crest is within this preferred range, the occurrence of condensation on the discharge surface of the spinneret can be suppressed regardless of the crest shape such as a circle or a rectangle.

In the present invention, the amount of air per unit time (Af) is from the wind speed of one point located on the upstream side of the airflow and the cross-sectional area when the spinneret is viewed from the upstream side of the airflow, among the wind speeds measured at four points of the outer periphery of the crest as a measurement point. Calculate. The volume Vh of the gaseous phase is calculated from the discharge area calculated from the outermost discharge hole of the custody and the height of the gaseous phase formed between the coagulation bath liquid surface vertically downward from the discharge surface. The amount of solvent (As) in the discharged stock solution is the amount of the solvent contained in the stock solution discharged from the detention per unit time.

In addition, in the present invention, the wind speed and absolute humidity of the four points of the outer periphery of the detention are, as shown in Fig. 1, the height from the liquid level to the detention surface of a point where the outer periphery of the detention is equally divided into four, regardless of the shape of the detention. Measure at the midpoint of and 30mm away from the outermost discharge hole of the custody. Here, in the present invention, the four points on the outer periphery of the detention are, for example, when the shape of the detention is circular, arbitrary four points on the outer circumference that uniformly divide the outer circumference into four can be selected, and the shape of the detention is rectangular. In this case, four midpoints of each line segment constituting the outer periphery can be selected. Wind speed, temperature, and relative humidity can be measured using Klimo Master MODEL6501 (Kanomax Co., Ltd.). Absolute humidity (AH)[g/m ³ ] is calculated from the temperature (T)[°C] and relative humidity (RH)[%] measured by KlimoMaster using the following calculation formula (e: saturated vapor pressure [hPa] )

e=6.11×10 ^{(7.5T/(T+237.3))}

AH=217×e/(T+273.15)×RH/100

Here, the 1-hour average value of the absolute humidity at the four outer periphery points of the detention is, as described above, the wind speed, temperature, and relative humidity are measured 12 times at 5-minute intervals, and the absolute humidity is calculated using the above calculation formula. It is an average value.

In addition, in the case of using an air supply or exhaust nozzle when supplying or exhausting gas, the direction of the nozzle is, as shown in FIG. 1, so that the nozzle outlet is in the direction of the mouth and parallel to the surface of the coagulation bath liquid, specifically, It is preferable that the installation angle of the nozzle is inclined from the vertical downward direction (referred to as 0°) toward the detent direction, preferably 60° or more and 120° or less, more preferably 80 to 100°, and more preferably 90 Let it be °. In FIG. 1, as an example, the case where the installation angle of a nozzle is 90 degrees is shown. When the installation angle (nozzle angle) of the nozzle is set to 90°, vapor generated from the solvent can be efficiently scavenged, and condensation adhesion to the spinneret can be suppressed extremely effectively. If the installation angle of the nozzle is within this preferred range, in the case of the air supply nozzle, it is difficult to make turbulent flow due to the airflow hitting the mouth surface, and the formation of condensation can be effectively prevented without retention, and in the case of the exhaust nozzle, The vapor generated from the solvent can effectively prevent the growth of droplets, although it is easy to be sucked while in contact with the orifice surface. On the other hand, since the flow of the coagulation bath liquid surface does not easily occur in both the air supply nozzle and the exhaust nozzle, it is possible to effectively suppress a phenomenon that adversely affects the quality and process stability, such as detention immersion in which the liquid surface contacts the detention and adhesion between single yarns.

The present invention exhibits a particularly effect when producing acrylonitrile-based fibers, particularly acrylonitrile-based fibers, which are carbon fiber precursors, using an acrylonitrile-based polymer, but the specific conditions in that case are described in detail below. Explain.

As the spinning dope in dry-wet spinning, a solution obtained by dissolving an acrylonitrile-based polymer composed of 90% by mass or more of acrylonitrile and a vinyl-based monomer copolymerizable therewith is used. When the copolymerization ratio of acrylonitrile in the acrylonitrile polymer is within this preferred range, the carbon fiber obtained by firing the acrylonitrile fiber obtained by the method of the present invention has high strength and excellent mechanical properties. It becomes easy to produce a carbon fiber having In addition, if the concentration of the polymer in the spinning dope is within this preferred range, the content of the solvent is appropriate, and the vapor amount of the solvent in the gas phase part between the spinneret and the coagulation bath liquid in dry-wet spinning is not too large, condensation is easily generated. On the other hand, viscosity increase and gelation when polymerizing an acrylonitrile-based polymer can be suppressed, and when performing dry-wet spinning, it is difficult to block the discharge holes of the spinneret, so the adhesion of fibers and fineness are uneven. Fiber breakage can be effectively prevented, and in addition, roller winding in subsequent processes, fluff in the stretching process, and yarn breakage can be effectively prevented, excellent operability, and deterioration of product quality can be effectively prevented. .

The present invention can be preferably employed in the case where the number of filaments per fiber is usually in the range of 2,000 to 50,000, and the single fiber fineness is usually in the range of 0.5 dtex to 3 dtex. Fibers fiberized in the coagulation bath may be directly stretched in a drawing bath, or may be stretched in a bath after removing the solvent by washing with water.

After stretching in a bath, an oil agent is usually applied and dried with a hot roller or the like. Further, if necessary, then, stretching such as steam stretching is performed to obtain fibers.

Hereinafter, a method for producing carbon fibers from fibers obtained by the method for producing fibers in which the fiber-forming polymer is an acrylonitrile-based polymer will be described.

The acrylonitrile-based fiber produced by the above-described method for producing an acrylonitrile-based fiber is subjected to a salt resistance treatment in an oxidizing atmosphere such as air at 200 to 300°C. The treatment temperature is preferably raised in multiple steps from a low temperature to a high temperature in terms of obtaining a flame-resistant fiber, and drawing the fiber at a high draw ratio within a range that does not involve the occurrence of fluff is sufficient to fully express the performance of the carbon fiber. It is preferable in terms of Next, the resulting flame-resistant fiber is heated to 1,000° C. or higher in an inert atmosphere such as nitrogen to produce carbon fiber. Thereafter, by performing anodic oxidation in an aqueous electrolyte solution, it becomes possible to impart a functional group to the surface of the carbon fiber and increase the adhesion to the resin. In addition, it is preferable to provide a sizing agent such as an epoxy resin to obtain a carbon fiber excellent in abrasion resistance.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples. In addition, the wind speed and absolute humidity of the four points of the outer periphery of the detention used in this example are the midpoint of the height from the liquid level to the detention surface at the point where the outer periphery of the detention in a rectangular shape is equally divided into four as shown in FIG. It was measured at a position 30 mm apart from the outermost discharge hole. Wind speed, temperature, and relative humidity were measured using Klimo Master MODEL6501 (Kanomax Co., Ltd.). Absolute humidity (AH) [g/m ³ ] was calculated from the temperature (T) [° C.] and relative humidity (RH) [%] measured by the Klimo Master using the following equation (e: saturated vapor pressure [hPa] ).

e=6.11×10 ^{(7.5T/(T+237.3))}

AH=217×e/(t+273.15)×RH/100

Here, the 1-hour average value of the absolute humidity at the four outer periphery points of the detention is, as described above, for each measurement point of which the wind speed, temperature, and relative humidity are measured 12 times at 5-minute intervals and the absolute humidity is calculated using the above calculation formula. It was set as the average value of.

In addition, the amount of air per unit time (Af) was calculated from the wind speed of one point located on the upstream side of the airflow and the cross-sectional area when the spinneret was viewed from the upstream side of the airflow among the wind speeds measured at 4 measurement points. The volume (Vh) of the gaseous phase was calculated from the discharge area calculated from the outermost discharge hole of the custody and the height of the gaseous phase formed between the coagulation bath liquid surface vertically downward from the discharge surface. The amount of solvent (As) in the discharged stock solution is the amount of solvent contained in the stock solution discharged from the detention per unit time.

The degree of condensation on the convex surface, the quality of the acrylonitrile fiber, and the process stability were determined as follows.

(The degree of condensation in detention)

The size and number of condensation on the spinneret face when spinning was continued for one week in a row were measured, and the score was converted to the following criteria.

Condensation diameter∼less than 2mm: 1 point/piece

Condensation diameter 2mm or more and less than 5mm: 5 points/piece

Condensation diameter of 5 mm or more: 10 points/piece.

(Quality of acrylonitrile fiber)

Immediately before winding up the acrylonitrile fiber, the number of fluffs of the acrylonitrile fiber for 1,000 m was counted, and the quality was evaluated in five stages. The evaluation criteria are as follows.

1: (number of fluff/1 fiber·1,000m)≤1

2: 1 <(number of fluff/1 fiber·1,000m)≤2

3: 2 <(number of fluff/1 fiber·1,000m)≤5

4: 5 <(number of fluff/1 fiber·1,000m) <60

5: 60≤(number of fluff/1 fiber·1,000m).

(Process stability of acrylonitrile fiber)

The evaluation was made in five steps from the number of yarn breaks in the production of 10 t of acrylonitrile fibers. The evaluation criteria are as follows.

1: (number of yarn breaks/acrylonitrile fiber 10t production) ≤ 1

2: 1 <(number of yarn breaks/acrylonitrile fiber 10t production) ≤ 2

3: 2 <(number of yarn breaks/acrylonitrile fiber 10t production) ≤ 3

4: 3 <(number of yarn breaks/manufactured by 10t of acrylonitrile fiber) <5

5: 5 ≤ (number of yarn breaks/acrylonitrile fiber 10t production)

<Examples 1 to 4>

A DMSO solution of an acrylonitrile polymer composed of 99% by mass of acrylonitrile and 1% by mass of itaconic acid was prepared by solution polymerization.

The obtained acrylonitrile-based polymer solution (spinning stock solution) was once discharged into the air from the discharge surface of the spinneret using a detent having a total number of 6,000 undiluted discharge holes, passed through the gas phase, and then DMSO 35% by mass/water 65% by mass It was discharged into the coagulation bath liquid consisting of %, and coagulated fiber was obtained.

Here, at the time of spinning, an air supply nozzle and an exhaust nozzle having an opening of 5 mm x 200 mm are installed on the front side of the spinneret so as to pinch the mouth, and the dehumidified air is blown from the air supply nozzle, and discharged by suction by the exhaust nozzle. The solvent vapor generated in the gas phase between the cotton and the coagulation bath was evacuated. In addition, in each example, the nozzle angle, Af/(As/Vh) of the supply/exhaust nozzle and the relative standard deviation of the wind speed at each of the four measuring points were changed as shown in Table 1. Table 1 shows the degree of condensation on the discharge side and the quality and process stability of the acrylonitrile fiber in each example.

After the obtained coagulated fiber was successively washed with water, an oil agent was applied while stretching in a bath stretching step, and further dried and stretched, an acrylonitrile-based fiber having 6,000 short fibers could be stably produced.

[Table 1]

<Example 5>

Af/(As/Vh) was changed as shown in Table 1, except that the degree of dehumidification was enhanced, and the same was carried out as in Examples 1 to 4 to obtain acrylonitrile-based precursor fibers.

<Example 6>

Af/(As/Vh) was changed as shown in Table 1, and except that a 9,000 hole confinement was used, it carried out in the same manner as in Examples 1 to 4 to obtain an acrylonitrile-based precursor fiber.

<Example 7>

Af/(As/Vh) was changed as shown in Table 1, and an acrylonitrile-based precursor fiber was obtained in the same manner as in Examples 1 to 4 except that a 2,000 hole confinement was used.

<Comparative Example 1>

Af/(As/Vh) was changed as shown in Table 1, except that the air supply/exhaust nozzle was not operated, and the procedure was carried out in the same manner as in Examples 1 to 4 to obtain an acrylonitrile-based precursor fiber.

<Comparative Example 2>

Except for changing Af/(As/Vh) as shown in Table 1, it carried out similarly to Examples 1-4, and obtained the acrylonitrile-type precursor fiber.

<Comparative Example 3>

Except that Af/(As/Vh) was changed as shown in Table 1 and the degree of dehumidification was weakened, it carried out similarly to Examples 1-4, and obtained the acrylonitrile-type precursor fiber.

<Comparative Example 4>

Except that Af/(As/Vh) was changed as shown in Table 1, and the degree of dehumidification was further weakened, it carried out similarly to Examples 1-4, and obtained the acrylonitrile-type precursor fiber.

<Comparative Example 5>

Except that Af/(As/Vh) was changed as shown in Table 1 and the supply air was not dehumidified, it was carried out in the same manner as in Examples 1 to 4 to obtain an acrylonitrile-based precursor fiber.

Table 1 shows the degree of condensation on the discharge side and the quality and process stability of acrylonitrile fibers in each of the Examples and Comparative Examples.

As shown in Table 1, it can be seen that the present invention suppresses condensation on the discharge surface of the prison and improves quality and process stability.

[Industrial availability]

The present invention is not limited to suppressing the occurrence of condensation on the spheroid surface in the production of carbon fiber precursor fibers, and can be applied as a productivity improvement measure by suppressing condensation in all dry and wet spinning.

1: spinneret
2: air supply nozzle or exhaust nozzle
3: coagulation desire
4: Wind speed/airflow measurement point A
5: Wind speed/airflow measurement point B
6: Wind speed/airflow measurement point C
7: Wind speed/airflow measurement point D

Claims (5)

In a method for producing a fiber in which a spinning dope obtained by dissolving a fiber-forming polymer in a solvent is discharged from a spinneret, once run in air, then delivered into a coagulation bath liquid and solidified,
The amount of air per unit time of the gaseous part (Af) formed vertically downward from the discharge surface of the spinneret and the surface of the coagulation bath liquid is the spinning dope per unit time in the volume of the gaseous part (Vh) With respect to the amount of solvent (As) in the solvent, the relational expression of 0.0008m ³ ≤Af/(As/Vh) ≤0.0015m ³ is satisfied, and the average value of the absolute humidity at 4 points in the outer periphery of the detention in the meteorological unit is 20g/m, respectively ³ or less, the manufacturing method of a fiber. The method of claim 1,
A method for producing a fiber, wherein the relative standard deviation of the wind speed at the four points of the outer periphery of the detention in the meteorological department is 40% or less. The method according to claim 1 or 2,
The number of holes in the spinneret is 2,000 or more and 50,000 or less. The method according to any one of claims 1 to 3,
The method for producing a fiber, wherein the fiber-forming polymer is an acrylonitrile-based polymer. A method for producing a carbon fiber, comprising producing a fiber by the method for producing a fiber according to claim 4, followed by a flame resistance treatment in an oxidizing atmosphere of 200 to 300°C, followed by heating in an inert atmosphere of 1,000°C or higher.

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