JP6121866B2 - Method for producing aromatic polyester fiber - Google Patents

Description

The present invention relates to a method for producing fine fibers (multifilaments having a single yarn fineness of 4.0 dtex or less) made of a melt anisotropic aromatic polyester.

Melt anisotropic aromatic polyester is a polymer composed of rigid molecular chains, and in melt spinning, the molecular chains can be highly oriented in the fiber axis direction. In addition, since the melt anisotropic aromatic polyester undergoes a polymerization reaction in a solid state, the highest strength among the fibers obtained by melt spinning is obtained by heat-treating the fiber after spinning at a high temperature and solid-phase polymerization. It is known to have an elastic modulus. Because of these characteristics, they have been used for screen printing cloths, sailcloths, cord reinforcements for various electrical products, protective gloves, plastic reinforcements, and optical fiber tension members. In recent years, it is expected to be used for a printed circuit board base fabric because of its high frequency characteristics such as low dielectric constant and low dielectric loss tangent and excellent dimensional stability. Furthermore, recently, with the miniaturization and thinning of mobile phones, personal computers, and tablets, demand for melt anisotropic aromatic polyester fibers with relatively fine total fineness and single yarn fineness is expected.

However, highly oriented melt-anisotropic aromatic polyester fibers have a low elongation at break and are therefore almost impossible to stretch after spinning. For this reason, in order to reduce the single yarn fineness, it is necessary to achieve the target single yarn fineness at the spinning stage. As a method for producing a melt anisotropic aromatic polyester fiber having a fine single yarn fineness, for example, in Patent Document 1, a sea-island type composite fiber using a water-dispersible polyester as a sea component and a melt anisotropic aromatic polyester as an island component is used. A melt-anisotropic aromatic with a single yarn fineness of 0.05 to 1.0 dtex and a strength after heat treatment of 20 cN / dtex or more by wrapping around cheese and dissolving sea components in the water in the form of cheese. A method for obtaining a polyester fiber has been proposed.
In Patent Document 2, in a melt spinning method in which an aromatic polyester capable of forming an anisotropic molten phase is discharged from a nozzle having a diameter of 0.1 mm or less and spun and wound, the following condition (1) A method for producing a melt-anisotropic aromatic polyester ultrafine fiber characterized by using (7) is proposed.
(1) Use a polymer having a melt viscosity of less than 500 poise at a melting point of the melt anisotropic aromatic polyester + 20 ° C. shear rate of 1000 sec ⁻¹ (2) A shear rate of 10 ³ to 10 ⁹ sec ⁻ when passing through the nozzle for ¹ to that (3) the discharge linear velocity be 5 m / min or more 40 m / min or less in the nozzle (4) the winding speed 150 meters / minute or more 8000 m / min to more than (5) said discharge outgoing rate The winding speed ratio is set to 20 or more. (6) The spinneret temperature is set to a melting point + 15 ° C. or higher. (7) The fiber temperature at a point 30 cm away from the nozzle surface after discharge is set to Tm-150 ° C. or lower. about

JP 2010-216052 A JP-A-6-166909

However, the sea-island type composite spinning method of Patent Document 1 requires a special process of elution of the sea component, which is a water-dispersible polyester. Therefore, in industrial production, not only the process is increased, but also the cost is increased. There is a problem of becoming higher.

On the other hand, the method of Patent Document 2 has the advantage that fibers having a fine single yarn fineness can be stably spun with a normal spinneret and has the advantage of low cost, but the fiber is unwound during rewinding or the like. , Fibrillation, single yarn breakage and breakage easily occur due to a decrease in the strength per single yarn, and stably produce a high-quality melt-anisotropic aromatic polyester fiber. It is insufficient as a method.

The present invention solves the above-mentioned problems and stabilizes a high-grade melt-anisotropic aromatic polyester fiber at a low cost without fibrillation or single-thread breakage in the rewinding and heat treatment processes while having a fine single yarn fineness. It is an object of the present invention to provide a manufacturing method.

As a result of intensive studies, the present inventors have found the present invention. That is, an object of the present invention is to provide a multifilament having a single yarn fineness of 4.0 dtex or less by melt spinning an aromatic polyester exhibiting anisotropy at the time of melting. It is achieved by a method for producing an aromatic polyester fiber characterized by being. This aromatic polyester fiber preferably has a total fineness of 10 dtex or more and 500 dtex or less and a filament number of 3 to 1000.

According to the present invention, high-quality aromatic polyester fibers having a single yarn fineness of 4.0 dtex or less, having no single yarn breakage and no fibrillation, excellent in post-process passability, and stably manufactured at low cost. I can do it.

It is explanatory drawing which shows the outline of an example of the melt spinning apparatus used for this invention.

Hereinafter, the present invention will be described in detail.

The aromatic polyester in the present invention is an aromatic polyester that exhibits anisotropy when melted. The aromatic polyester that exhibits anisotropy when melted is a temperature at which the polyester sample powder can flow when heated by placing the polyester sample powder on a heated sample stage between two polarizing plates orthogonal to each other by 90 °. In the region, it means having the property of transmitting light. Examples of such aromatic polyesters include aromatic dicarboxylic acids, aromatic diols and / or aromatic hydroxycarboxylic acids and derivatives thereof described in JP-B-56-18016 and JP-B-55-20008. In some cases, a copolymer of these with an alicyclic dicarboxylic acid, an alicyclic diol, an aliphatic diol or a derivative thereof is also included. Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 4,4′-dicarboxydiphenyl, 2,6-dicarboxynaphthalene, 1,2-bis (4-carboxyphenoxy) ethane, and the like. And those obtained by substituting hydrogen of a group ring with an alkyl, aryl, alkoxy or halogen group. Aromatic diols include hydroquinone, resorcin, 4,4′-dihydroxydiphenyl, 4,4′-dihydroxybenzophenone, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylethane, 2,2-bis (4 -Hydroxyphenyl) propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, etc. And those obtained by substituting hydrogen of an aromatic ring with an alkyl, aryl, alkoxy or halogen group. Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxynaphthalene-6-carboxylic acid, 1-hydroxynaphthalene-5-carboxylic acid, and hydrogen of these aromatic rings. Examples thereof include those substituted with an alkyl, aryl, alkoxy or halogen group. Examples of alicyclic dicarboxylic acids include trans-1,4-dicarboxycyclohexane, cis-1,4-dicarboxycyclohexane, and the like, and hydrogens of these aromatic rings substituted with alkyl, aryl, alkoxy, or halogen groups. Is mentioned. Examples of the alicyclic and aliphatic diols include trans-1,4-dihydroxycyclohexane, cis-1,4-dihydroxycyclohexane, ethylene glycol, 14-butanediol, and xylylenediol.

Among these combinations, preferred aromatic polyesters in the present invention include, for example, (1) 40-70 mol% of p-hydroxybenzoic acid residue and / or 2-hydroxynaphthalene-6-carboxylic acid residue and the above-mentioned Copolyester composed of 15-30 mol% aromatic dicarboxylic acid residue and 15-30 mol% aromatic diol residue, (2) Consists of terephthalic acid and / or isophthalic acid and chlorohydroquinone, phenylhydroquinone, and / or hydroquinone Copolyester, (3) copolyester composed of 20 to 80 mol% of p-hydroxybenzoic acid residue and 20 to 80 mol% of 2-hydroxynaphthalene-6-carboxylic acid residue.

In order to obtain the aromatic polyester used in the present invention using these starting materials, esterification as it is or with an aliphatic or aromatic monocarboxylic acid or a derivative thereof, an aliphatic alcohol or a phenol or a derivative thereof, or the like. To carry out the polycondensation reaction. As the polycondensation reaction, known block polymerization, solution polymerization, suspension polymerization and the like can be adopted, and the obtained polymer may be used as it is as a spinning sample, or in a powdery inert gas, Or it is good also as a sample for spinning by heat-processing under pressure reduction. Alternatively, it may be granulated once by an extruder.

In the component, other polymers or additives (pigment, carbon, heat stabilizer, ultraviolet absorber, lubricant, fluorescent whitening agent, etc., as long as the physical properties of the melt anisotropic aromatic polyester fiber are not substantially lowered. ) May be included.

The aromatic polyester in the present invention has a molecular weight range suitable for spinning. “Flow start temperature” is used as a physical property value corresponding to the molecular weight suitable for the melt spinning conditions. “Flow start temperature” is a temperature tester using a flow tester CFT-500 manufactured by Shimadzu Corporation, with a nozzle having a diameter of 1 mm and a length of 10 mm and a pressure of 100 kg / cm ² and raising the temperature of the aromatic polyester sample at 4 ° C./min. And the temperature at which the sample flows through the nozzle and gives an apparent viscosity of 4,800 Pascal seconds.

The “flow start temperature” of the aromatic polyester suitable for melt spinning of the present invention is preferably 290 to 330 ° C.

The single yarn fineness of the aromatic polyester fiber in the present invention is 4.0 dtex or less, preferably 2.5 dtex or less, more preferably 1.0 dtex or less. The range of the total fineness is preferably 10 to 500 dtex, more preferably 15 to 450 dtex, and still more preferably 20 to 400 dtex. The range of the number of filaments is preferably 3 to 1000, more preferably 10 to 800, and still more preferably 20 to 600.

The aromatic polyester suitable for melt spinning of the present invention preferably has a melting viscosity of 10 Poise or more and 50 Poise or less at a melting point of + 30 ° C. and a shear rate of 1000 sec ⁻¹ . Within this range, it is suitable for stably producing aromatic polyester fibers having a single yarn fineness of 4.0 dtex or less. That is, when the melt viscosity is less than 10 poise, the polymer extruded from the die tends to be wrinkled and tends to lack spinning stability. When the melt viscosity exceeds 50 poise, there is a possibility that single yarn breakage may occur as the fineness is reduced, and the spinning stability tends to be lacking. Note that the melt viscosity was measured by using a capillograph (Model 1B, manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a nozzle having a diameter of 0.5 mm and a length of 5 mm. It is defined as the viscosity at a shear rate of ^-1 .

The production method of the present invention is performed, for example, by using a melt spinning apparatus as shown in FIG. In FIG. 1, 1 is a spinning head, 2 is a spinning pack, 3 is a spinneret, 4 is a heater, and 5 is a heat retaining cylinder.

In melt spinning, a known method may be used for melt extrusion of the aromatic polyester. The aromatic polyester is usually pelletized so as to be suitable for melt spinning, and an extruder type extruder is used. The extruded resin passes through a pipe, is sent to the spinning head 1, is metered by a known metering device (not shown) such as a gear pump, passes through a filter in the spinning pack 2, and then enters the spinneret 3. The temperature from the polymer pipe to the spinneret 3 is preferably not less than the melting point of the aromatic polyester and not more than the thermal decomposition temperature.

By installing the heater 4 and the heat retaining cylinder 5 immediately below the spinneret 3, the diameter of the discharged fiber is stabilized, and changes in the spinneret surface temperature and the atmospheric temperature under the spinneret can be suppressed by the outside air, There is a tendency that thinning in the draft becomes uniform, and there is no yarn breakage or fluff generation, and stable spinning tends to occur.

Moreover, it is preferable that the shear rate in the spinneret hole is 10 ⁴ to 10 ⁵ sec ⁻¹ . The shear rate γ referred to in the present invention is determined by the following equation.
γ = 4Q / πr ³
(Where r is the radius of the spinneret hole (cm), Q is the amount of polymer discharged per single hole (cm ³ / sec))
Within the above range, the orientation of the fibers becomes sufficient, fibers with a fineness are easily obtained, and the desired physical properties tend to be obtained.

In the case of aromatic polyester fiber, since it is difficult to draw in the subsequent process after spinning and winding, in order to obtain a multifilament having a single yarn fineness of 4.0 dtex or less, resin is discharged from the pores as much as possible. It is preferable to do. For this purpose, the hole diameter (diameter) of the spinneret is preferably 0.2 mm or less, and more preferably 0.18 mm or less.

The aromatic polyester fiber spun as described above is applied with a predetermined oil agent by the oil agent applying device 6, and then taken up by the first godet roll 7 and the second godet roll 8, and is taken up by a take-up bobbin 9 (spinning take-up bobbin). ). The spinning winding tension measured between the second godet roll 8 and the winding bobbin 9 is preferably 5 cN or more and 60 cN or less, more preferably 10 cN or more and 50 cN or less, and further preferably 20 cN or more and 40 cN or less. When the tension is less than 5 cN, the fiber is loosened, whereby the yarn is wound around the godet roll 8 or the winding bobbin 9 has a defective shape. Normally, if the fiber exceeds a single yarn fineness of 4.0 dtex, it can be stably wound even if the spinning winding tension is about 70 to 100 cN without causing the shape of the spinning winding bobbin to collapse. When the single yarn fineness is 4.0 dtex or less, when the spinning winding tension exceeds 60 cN, single yarn breakage or fibrillation occurs in the yarn breakage during spinning and the subsequent rewinding process, and the yarn quality is impaired. In the present invention, the spinning winding tension is a value measured for the tension applied when winding with the winding bobbin 9.

The important point in the present invention is that the spinning winding tension is 5 cN or more and 60 cN or less. Conventional aromatic polyester fibers are mainly used for industrial materials such as ropes and cables. The total fineness is thick, the single yarn fineness exceeds 4.0 dtex, and the strength per single yarn is generally 20 cN or more. It was. When the single yarn fineness is 4.0 dtex or less, the strength per single yarn is reduced, and fibrillation, single yarn breakage and breakage easily occur even with slight damage. In addition, since the aromatic polyester fiber has an extremely low elongation as compared with a general polyester fiber, the tension applied to the fiber cannot be absorbed, which causes fibrillation and yarn breakage. Furthermore, when the single yarn fineness is 4.0 dtex or less, the bulk density of the take-up bobbin becomes high. At this time, since the folded single yarns are easy to bite, when the fibers of the take-up bobbin are unwound, the single yarns interfere with each other to cause fibrillation or single yarn breakage. Therefore, in the present invention, the winding tension is set to 5 cN or more and 60 cN or less at the time of spinning, the burden on the yarn at the time of spinning winding is reduced as much as possible, and the bulk density of the spinning winding bobbin is reduced as much as possible. By reducing the bite of the single yarn, fibrillation, single yarn breakage and yarn breakage can be prevented, and high-quality aromatic polyester fibers can be stably produced.

Even if the aromatic polyester fiber obtained as described above is a fine fiber having a single yarn fineness of 4.0 dtex or less, there is no single yarn breakage or fibrillation in the rewinding or heat treatment described later, and the subsequent process passes. It is of high quality with excellent properties.

The strength of the fiber obtained by melt spinning the aromatic polyester is preferably 3.0 cN / dtex or more, more preferably 5.0 cN / dtex or more. Further, the elongation is preferably 0.5% or more, and more preferably 1.0% or more. Furthermore, the elastic modulus is preferably 300 cN / dtex or more, and more preferably 400 cN / dtex or more.

The aromatic polyester fiber obtained by spinning can be used as it is, but can be further increased in strength and elasticity by heat treatment. In this case, it is preferable that the fiber of the spin-winding bobbin is once wound around another bobbin for heat treatment before heat treatment to form a package. At this time, as described above, by setting the spinning winding tension in the spinning process to 5 cN or more and 60 cN or less, the unwinding property of the fiber in the rewinding is improved, and there is no single yarn breakage or yarn breakage. High-quality yarn can be obtained. It is preferable that the bulk density of the package be 0.01 g / cc or more and 1.0 g / cc or less, and 0.8 g / cc or less so that solid phase polymerization can proceed uniformly when the heat treatment bobbin is rolled back. More preferably. Here, the bulk density is a value calculated by Wf / Vf from the occupied volume Vf (cc) of the fiber and the mass Wf (g) of the fiber obtained from the outer dimension of the package and the outer dimension of the heat treatment bobbin as a core material. It is. The occupied volume Vf is a value obtained by actually measuring the outer dimensions of the package and assuming that the wound bobbin is rotationally symmetric, and Wf is calculated from the fineness and the winding length. It is a value measured by a value or a mass difference before and after winding. In order to reduce the bulk density, the rewinding speed is preferably 500 m / min or less, and more preferably 400 m / min or less.

The heat treatment is preferably performed at a temperature not higher than the melting point of the aromatic polyester fiber. Thereby, solid phase polymerization progresses and the strength and elastic modulus of the aromatic polyester fiber can be improved. It should be noted that, since there is a tendency that the fibers are easily fused during the heat treatment, it is preferable to raise the temperature stepwise from room temperature to a temperature below the melting point in order to prevent fusion between the fibers.

During the heat treatment, it is preferable to carry out in an inert gas atmosphere in order to stably advance the solid phase polymerization. However, it is desirable to dehumidify in advance to a dew point of −40 ° C. or lower when dry air is used in terms of cost. That is, if water is present during solid phase polymerization, hydrolysis may be induced and the strength may not be sufficiently increased.

Although the fiber after heat treatment can be used as a product as a package, it is preferably rewound around a paper tube or the like in order to increase the product carrying efficiency. In the rewinding after the heat treatment, the upper limit of the rewinding speed is not particularly limited, but is preferably 500 m / min or less, more preferably 400 m / min or less from the viewpoint of reducing damage to the fiber.

By performing the heat treatment as described above, aromatic polyester fibers having higher strength, higher elastic modulus, and higher quality can be stably obtained with high production efficiency. The strength of the fiber obtained by heat treatment as described above is preferably 10.0 cN / dtex or more, more preferably 12.0 cN / dtex or more, and further preferably 20.0 cN / dtex or more. Further, the elongation is preferably 1.0% or more, and more preferably 2.0% or more. Furthermore, the elastic modulus is preferably 400 cN / dtex or more, and more preferably 500 cN / dtex or more.

The present invention will be specifically described below with reference to examples. In Examples and Comparative Examples, aromatic polyester fibers were spun using the melt spinning apparatus shown in FIG. In addition, this invention is not limited to the Example described below. Each evaluation in the examples was performed as follows.

1) Tensile test (strength, elongation, elastic modulus)
In accordance with the standard time test of JISL 1013 (2010), using a tensile tester AGS-500NX manufactured by Shimadzu Corporation, the breaking strength and elastic modulus (initial tensile resistance) are obtained at a sample length of 200 mm and a pulling speed of 200 mm / min. Expressed as an average of 10 points.

2) Spinning Winding Tension Using the electronic tension meter CM-100R manufactured by Kanai Koki Co., Ltd., measuring the traveling tension between the second godet roll 8 and the winding bobbin 9 in FIG. Expressed as an average value.

3) Spinning operability evaluation Spinning operability when spinning for 2 hours or more was evaluated as follows.
○ Stable spinning with no yarn breakage.
Δ: No more than 5 yarn breaks occurred during spinning for 2 hours.
X Thread breakage occurred frequently and could not be wound.

4) Evaluation of Spinning Spinning Rewinding The operability when the spun fiber was wound on an iron bobbin by 50000 m was evaluated as follows.
○ There was no single thread breakage or thread breakage, and the rewinding was stable.
△ Single thread breakage or thread breakage occurred.
× The yarn breakage occurred frequently and could not be rewound to the end.

5) Evaluation of rewinding of heat treated yarn The operability when the fiber after the heat treatment was rewound about 50000 m in the product paper tube was evaluated as follows.
○ There was no single thread breakage or thread breakage, and the rewinding was stable.
△ Single thread breakage occurred.
× The yarn breakage occurred frequently and could not be rewound to the end.

6) Evaluation of the number of fluff The yarn after heat treatment was measured for a yarn length of 50000 m using a fluff detector F9-AN manufactured by Kasuga Denki Co., Ltd., and the measurement results were evaluated as follows.
○ No fuzz
△ 1 to 2 fluff × 3 or more fluff

[Example 1]
As an aromatic polyester exhibiting melt anisotropy, an aromatic polyester polymerized with 40 mol of p-acetoxybenzoic acid, 15 mol of terephthalic acid, 5 mol of isophthalic acid and 20.2 mol of 4,4′-diacetoxydiphenyl was used. . This aromatic polyester had a melting point of 340 ° C., a melting point of + 30 ° C., and a melt viscosity at a shear rate of 1000 sec ⁻¹ of 30 poise. The aromatic polyester was dried in a vacuum dryer at 140 ° C. for 24 hours to obtain a moisture content of 5 ppm, melt-extruded with a single screw extruder, measured with a gear pump, and supplied to the spinning pack. The spinning temperature from the extruder outlet to the spinning pack at this time was 360 ° C. Resin was discharged at a discharge rate of 11.6 cc / min from a spinneret having 48 holes with a hole diameter of 0.09 mm. An oil agent was applied to the discharged resin, led to the first godet roll and then the second godet roll, and both 48 filaments were wound on a winding bobbin at 867 m / min to obtain an aromatic polyester fiber. The winding tension (spinning winding tension) at this time was 20 cN. During winding for about 120 minutes, yarn breakage did not occur and spinning operability was good. The total fineness of the obtained fiber was 144.3 dtex, the strength was 7.1 cN / dtex, the elongation was 2.1%, and the elastic modulus was 480 cN / dtex. Subsequently, the spinning winding bobbin was rewound at 300 m / min from the heat treatment bobbin. During the rewinding of 50000 m, no single yarn breakage or yarn breakage occurred, the rewinding could be carried out well, and the operability was also good. This fiber was treated in nitrogen at 310 ° C. for 10 hours, and then wound from a heat-treated bobbin to a paper tube. During the rewinding of 50000 m, no single yarn breakage or yarn breakage occurred, the rewinding could be carried out well, and the operability was also good. The obtained fiber was a fiber having a total fineness of 144.3 dtex, a single yarn fineness of 3.0 dtex, a strength of 26.0 cN / dtex, an elongation of 2.4%, and an elastic modulus of 1000 cN / dtex. The number of fluffs of the heat-treated fiber wound around the paper tube was 0 during the measurement of 50000 m, which was a good quality. The spinning conditions and results are shown in Table 1.

[Examples 2 to 16]
An aromatic polyester fiber was obtained by spinning in the same manner as in Example 1 except that the aromatic polyester used in Example 1 was used and the total fineness, single yarn fineness, and spinning winding tension were changed as shown in Table 1. Next, in the same manner as in Example 1, the obtained aromatic polyester fiber was wound from a spinning winding bobbin onto a heat-treated bobbin, treated in nitrogen, and wound from the heat-treated bobbin to a paper tube to obtain a heat-treated aromatic polyester fiber. It was. As shown in Table 1, the rewinding of the aromatic polyester fiber was good with no single yarn breakage or yarn breakage before and after the heat treatment. The number of fluffs of the fiber after the heat treatment was 0 during the measurement of 50000 m, which was a good quality.

[Examples 17 and 18]
An aromatic polyester fiber was obtained by spinning in the same manner as in Example 1 except that an aromatic polyester having a melting point of + 30 ° C. and a melt viscosity of 20 poise and 40 poise at a shear rate of 1000 sec ⁻¹ was used and the spinning temperature was changed. Next, in the same manner as in Example 1, the obtained aromatic polyester fiber was wound from a spinning winding bobbin onto a heat-treated bobbin, treated in nitrogen, and wound from the heat-treated bobbin to a paper tube to obtain a heat-treated aromatic polyester fiber. It was. As shown in Table 1, the rewinding of the aromatic polyester fiber was good with no single yarn breakage or yarn breakage before and after the heat treatment. The number of fluffs of the fiber after the heat treatment was 0 during the measurement of 50000 m, which was a good quality.

[Comparative Example 1]
Except that the spinning winding tension was changed to 4 cN, the resin was discharged in the same manner as in Example 1, the oil agent was applied, and spinning was performed. However, as soon as it was wound around the take-up bobbin 9, the yarn was taken up by the godet roll 8, and the yarn was broken immediately.

[Comparative Example 2]
An aromatic polyester fiber after heat treatment was obtained in the same manner as in Example 1 except that the spinning winding tension was changed to 70 cN. In the rewinding of the aromatic polyester fiber, single yarn breakage or breakage occurred both before and after the heat treatment, and the number of fluffs of the fiber after the heat treatment was 5 during the measurement of 50000 m, which was of poor quality. .

[Comparative Example 3]
Spinning was performed in the same manner as in Comparative Example 1 except that the single yarn fineness was changed to 5.0 dtex. However, as soon as it was wound around the take-up bobbin 9, the yarn was taken up by the godet roll 8, and the yarn was broken immediately.

[Comparative Example 4]
An aromatic polyester fiber after heat treatment was obtained in the same manner as in Comparative Example 2 except that the single yarn fineness was changed to 5.0 dtex. The rewinding of the aromatic polyester fiber was good with no occurrence of single yarn breakage or yarn breakage before and after the heat treatment. Further, the number of fluffs of the fiber after the heat treatment was 0 during the measurement of 50000 m, which was a good quality.

  When the aromatic polyester fibers after the heat treatment of Examples 1 to 18 were processed into a woven fabric, there was no warping in the warping process or weft driving, and the process passability was excellent. What was obtained from Comparative Example 2 had a warping process and yarn breakage by weft driving, and the process passing ability was poor.

The aromatic polyester fiber obtained by the production method of the present invention has characteristics of high strength and high elastic modulus even though it is fine, and since there is no single yarn breakage or fibrillation, post-process passability is greatly improved. The

  For this reason, it is widely used in the fields of general industrial materials, electrical materials (especially as tension members), civil engineering / building materials, protective clothing, sports applications, automobile members, rubber reinforcement materials, acoustic materials, general clothing, and the like. Effective applications include ropes, nets, fish nets, printed circuit boards, air bags, airships, domes, etc., rider suits, fishing lines, various lines (yachts, paragliders, balloons, kites), blind cords Support cords for screen doors, various cords in automobiles and airplanes, power transmission cords for electrical products and robots, etc. Especially effective uses include printed circuit board base fabrics. Among them, there is a strong demand for fineness, weaving It can be most suitably used as a base fabric that requires suppression of product defects due to generation of fluff during the process in order to improve properties and fabric quality.

1 Spinning head
2 Spin Pack 3 Spinneret 4 Heater 5 Insulating Cylinder 6 Oil Supply Device 7 First Godet Roll 8 Second Godet Roll 9 Winding Bobbin

Claims (2)

In the method for producing an aromatic polyester fiber obtained by melt spinning an aromatic polyester exhibiting anisotropy when melted to obtain a multifilament having a single yarn fineness of 4.0 dtex or less, the spinning winding tension is 5 cN or more and 60 cN or less. A method for producing an aromatic polyester fiber. The manufacturing method of the aromatic polyester fiber of the aromatic polyester fiber obtained by the method of Claim 1 which is the range whose total fineness is 10 dtex or more and 500 dtex or less and the number of filaments is 3-1000.

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