JP5069659B2 - Para-type wholly aromatic copolyamide fiber and method for producing the same - Google Patents

Description

  The present invention relates to a para-type wholly aromatic copolyamide fiber excellent in water repellency and suppressing a decrease in water repellency over time, and a simple production method thereof.

  Conventionally, wholly aromatic polyamide fibers mainly composed of an aromatic dicarboxylic acid component and an aromatic diamine component, particularly para-type wholly aromatic copolyamide fibers, have characteristics such as strength, high elastic modulus, and high heat resistance. Therefore, it is widely used in various industrial materials such as cable strength members and ropes.

  In recent years, in the field of cables and ropes, for the purpose of protecting the core wire in the cable, there is an increasing need for fibers having water-blocking properties that impart water repellency to para-type wholly aromatic copolyamide fibers. Also, in the field of protective clothing such as fire fighting clothes, high water repellency is required for fire fighting work.

  Various methods for imparting water repellency to such para-type wholly aromatic copolyamide fibers have been studied. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-291372), a treatment containing a water repellent is proposed. There has been reported a method of immersing a fiber structure in a liquid and performing water repellent processing in a specific pH range. Although such a method can temporarily impart a water repellency effect to fibers and fiber structures, the water repellant is gradually removed due to friction between yarns during long-term use or use, and the water repellency over time. From the viewpoint of permanently imparting water repellency to the fiber and its structure, it is not preferable because the treatment is required again. In general, para-type wholly aromatic copolyamide fibers have an inactive fiber surface. Therefore, in the method of applying an agent to the surface of such a water repellent or oil, the affinity between the fiber and such an agent is increased. There is a problem that it is scarce and easily removed compared to other fibers.

As another approach, various methods have been studied in which the surface of a para-type wholly aromatic copolyamide fiber is surface-treated with a silane agent to impart water repellency and antifouling properties. -273093) and Patent Document 3 (Japanese Patent Laid-Open No. 2004-762231) and the like, the fiber surface is coated with a silane-based coating agent or a processing agent mainly composed of fluorocarbon silane, and the water repellency, antifouling property, etc. Work clothes and textile products that have been granted are reported. Such a method reacts with a silane agent or the like on the fiber surface and coats the agent on the fiber surface, so that a decrease in water repellency over time is suppressed compared to simply applying a water repellent. However, when the fiber surface such as para-type wholly aromatic copolyamide fiber is inactive as described above, there is no chemical / physical bonding force between the coating agent and the fiber surface. In addition, not only the surface coating agent is easily removed by bending or rubbing the yarn during use, resulting in a decrease in water repellency, but such treatment requires a certain reaction time and is carried out within the fiber manufacturing process. Since it is difficult to perform offline processing, productivity is poor and it is not preferable from the viewpoint of efficient processing and production of textile products.
In view of such a current situation, development of a para-type wholly aromatic copolyamide fiber that is excellent in water repellency and has little decrease in water repellency with time and a simple production method thereof are highly desired.

JP 2006-291372 A JP 2005-273093 A JP 2004-762231 A

  The present invention has been made against the background of the above-described prior art, and provides a para-type wholly aromatic copolyamide fiber that is excellent in water repellency and hardly deteriorates over time in water repellency, and a simple production method thereof. The purpose is to do.

  As a result of intensive studies to achieve the object, the present inventor uses the para-type wholly aromatic copolyamide fiber for the purpose of suppressing the fusion of single yarns in the heat drawing process in the production process. Attention was paid to the anti-fusing agent. This anti-fusing agent is applied after the polymer dope is discharged from a spinneret and subjected to a coagulation / water washing step, and inorganic fine particles such as talc are used from the viewpoint of heat resistance and versatility when passing through a hot drawing step. However, by using inorganic fine particles having high water repellency such as water-repellent silica and excellent heat resistance, in addition to serving as an anti-fusing agent when passing through the fiber manufacturing process, the obtained fiber itself It has been found that water repellency can be imparted. Furthermore, by applying inorganic fine particles at a stage where the strength is weak, it is not only simply adhered to the fiber surface, but also easily embedded in the fiber surface when passing through the subsequent process. Since it adheres firmly and cannot be easily removed, it is possible to permanently impart water repellency to the fiber itself. Since unevenness was formed, it was also found that the water repellency was increased by the physical unevenness effect, and the present invention was reached.

And thus, para-type wholly aromatic copolyamide fibers of the present invention, water-repellent silica particles adhering to the para-type wholly aromatic copolyamide fiber surface at ^{10mg / m 2 ~700mg / m 2} , and the resulting The critical surface tension of the para-type wholly aromatic copolyamide fiber is 10 mN / m to 20 mN / m.

  According to the present invention, an aromatic copolyamide fiber that can impart water repellency to a para-type wholly aromatic copolyamide fiber in a simple and efficient manner and that suppresses a decrease in water repellency over time can be obtained. It is useful in various industrial material applications such as tensile body applications and protective clothing applications such as fire clothes.

Hereinafter, embodiments of the present invention will be described in detail.
The para-type wholly aromatic copolyamide in the present invention is a polymer in which one kind or two or more kinds of divalent aromatic groups are directly linked by an amide bond, and is generally an amide polar solvent according to a known method. Among them, it can be obtained by polycondensation reaction of aromatic dicarboxylic acid dichloride and aromatic diamine. At this time, the aromatic group may be one in which two aromatic rings are bonded with oxygen, sulfur, or an alkyl group. In addition, these divalent aromatic rings may be unsubstituted or substituted with a lower alkyl group such as a methyl group or a methyl group, or a halogen group such as a methoxy group or a chlorine group. The type and the number of substituents are not particularly limited.

  Examples of the aromatic dicarboxylic acid dichloride in the present invention include terephthalic acid dichloride, 2-chloroterephthalic acid dichloride, 3-methylterephthalic acid dichloride, 4,4′-biphenyldicarboxylic acid dichloride, 2,6-naphthalenedicarboxylic acid dichloride, and isophthalic acid. Acid dichloride and the like can be mentioned, but terephthalic acid dichloride is most preferable from the viewpoints of versatility and mechanical properties of the fiber. One or more of these aromatic dicarboxylic acid dichlorides can be used, and the composition ratio is not particularly limited.

  Examples of the aromatic diamine in the present invention include paraphenylene diamine, 3,4'-diaminodiphenyl ether, parabiphenylene diamine, 5-amino-2- (4-aminophenylene) benzimidazole, 1,4-dichloroparaphenylene diamine, Examples include, but are not limited to, metaphenylenediamine, and the aromatic ring may have a substituent or other heterocyclic ring.

  In the present invention, two or more of these aromatic diamines are used. The combination is most preferably a combination of paraphenylenediamine and 3,4′-diaminodiphenyl ether from the viewpoints of versatility and mechanical properties of the fiber, and the composition ratio is not particularly limited. 30 to 70 mol% and 70 to 30 mol% are preferred, respectively, more preferably 40 to 60 mol% and 60 to 40 mol%, most preferably 45 to 55 mol% and 55 to 55 mol%, respectively, with respect to the amount of the group diamine. 45 mol%.

  Examples of the amide solvent in the present invention include N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”), N, N-dimethylformamide, N, N-dimethylacetamide, dimethylimidazolidinone and the like. NMP is most preferable from the viewpoints of versatility, harmfulness, handleability, and solubility in aromatic copolyamide polymers.

  The water-repellent silica fine particles in the present invention refer to silica fine particles that have been chemically modified on the surface of ordinary silica fine particles to impart water repellency. Examples of the modifying group introduced on the surface of the silica fine particles from the viewpoint of water repellency include, but are not limited to, a hydrophobic group such as a methyl group, an ethyl group, a propyl group, a butyl group, and an isopropyl group. Further, the degree and method of the surface modification are not particularly limited.

  With respect to the water-repellent silica fine particles, for example, JP-A-9-110414, JP-A-9-241016 (above, Kunimine Industry Co., Ltd.), JP-A-6-115924 (Nittetsu Mining Co., Ltd.), JP-A-2003. In addition to being described in detail in No. -342017 (Ishihara Pharmaceutical Co., Ltd.) and the like, commercially available products include SP-03F manufactured by Fuso Chemical Industry Co., Ltd., Aerosil R805 manufactured by Nippon Aerosil Co., Ltd., and the like.

  In addition, the average particle diameter (D50) of the water-repellent silica fine particles in the present invention is preferably 10 nm to 500 nm, more preferably 30 nm to 400 nm, and most preferably 50 nm to 300 nm. When the average particle diameter (D50) of the water-repellent silica fine particles is less than 10 nm, not only is it difficult to produce such small particles in the first place, but even if such fine particles are obtained, they are aggregated during storage. Is likely to occur, which is not preferable in terms of handling. Further, since the water-repellent silica fine particles adhering to the fiber surface inevitably decreases in the water-repellent silica fine particles adhering to the fiber surface because the particle diameter is too small, there is a possibility that the particle may easily fall off from the fiber surface. Absent. On the other hand, when the average particle diameter (D50) exceeds 500 nm, the particle diameter becomes large, so that sedimentation occurs easily during storage in a slurry state, for example, and uniform application to the fibers becomes difficult. In addition, since the particle diameter is too large, only a part of the fine particles can be embedded in the fiber surface, and therefore, the fine particles easily fall off by rubbing or bending, which is not preferable.

  The average particle size (D50) mentioned here is measured using a laser diffraction type particle size distribution measuring device (device name: SALD-200VER, manufactured by Shimadzu Corporation) by dispersing fine particles in water. D50 is the 50th particle size counted from the smallest particle size when measuring the particle size of 100 samples, and means the average particle size of the measurement sample To do.

  The polymer dope in the present invention refers to a polymer solution in which a para-type wholly aromatic copolyamide polymer is dissolved in a solvent that can be dissolved therein. If the solvent used in the polycondensation reaction between the aromatic dicarboxylic acid dichloride and the aromatic diamine is also a good solvent for the aromatic copolyamide polymer, the polymer after the polycondensation reaction is not isolated. It can be used as a polymer dope as it is. In addition, an inorganic salt can also be used as a dissolution aid for the purpose of increasing the solubility of the polymer in the solvent. Examples of the inorganic salt include, but are not limited to, calcium chloride and lithium chloride. Further, the amount of the inorganic salt added to the polymer dope is not particularly limited, but from the viewpoint of the effect of improving the polymer solubility, the solubility of the inorganic salt in the solvent, etc., 3 to 10 wt. % Is preferred.

Next, the method of the present invention will be described.
In the present invention, a para-type wholly aromatic copolyamide polymer is first polymerized.
In this polymerization, a known polycondensation reaction is applied, an amide solvent such as NMP is added to a reaction vessel, and aromatic diamines such as paraphenylenediamine and 3,4′-diaminodiphenyl ether are dissolved therein, respectively. An aromatic dicarboxylic acid dichloride such as terephthalic acid dichloride is added to the polycondensation reaction. At this time, the amount of the aromatic diamine to be added is 30 to 70 mol% and 70 to 30 mol%, respectively, of paraphenylenediamine and 3,4'-diaminodiphenyl ether when the total amount of the aromatic diamine is 100 mol%. More preferably, they are 40-60 mol% and 60-40 mol%, respectively, Most preferably, they are 45-55 mol%, 55-45 mol%, respectively. Moreover, the quantity of the aromatic dicarboxylic acid dichloride added is 95-105 mol% with respect to aromatic diamine. When the aromatic dicarboxylic acid dichloride is less than 95 mol% and exceeds 105 mol%, the reaction with the aromatic diamine does not proceed sufficiently, and a high degree of polymerization cannot be obtained.

  Thereafter, a polycondensation reaction between the aromatic diamine and the aromatic dicarboxylic acid dichloride is performed using a known stirrer. The reaction temperature and reaction time at this time vary greatly depending on the reaction temperature, and can be appropriately adjusted while watching the progress of the polymerization.

After completion of the reaction, hydrochloric acid is generated in the system due to the polycondensation reaction of aromatic diamine and aromatic dicarboxylic acid dichloride, and the system becomes acidic. For the purpose of neutralization, an alkali such as calcium hydroxide is added. . The amount of alkali added varies depending on the type of alkali and the amounts of aromatic diamine and aromatic dicarboxylic acid dichloride, but when calcium hydroxide is used, it is preferably 95 to 100 mol% with respect to the aromatic dicarboxylic acid dichloride. When calcium hydroxide is less than 95 mol%, neutralization cannot be carried out sufficiently, the inside of the system still shows acidity and causes depolymerization, which is not preferable. On the other hand, when it exceeds 100 mol%, the inside of the system shows an alkali, which is also not preferable because it causes depolymerization.
The calcium chloride generated by the neutralization reaction can be used as it is as a solubilizing agent that enhances the dissolution of the produced polymer in the solvent, and therefore does not need to be removed from the system.

  The para-type wholly aromatic copolyamide polymer thus obtained is an isotropic polymer dope dissolved in NMP and can be used as it is in the spinning process without isolation. However, at this time, the concentration of the para-type wholly aromatic copolyamide polymer significantly affects the viscosity and stability of the polymer dope, and greatly affects the spinnability and the like in the subsequent spinning process. Therefore, the polymer concentration is preferably 2 to 10% by weight. Therefore, an appropriate amount of N-methyl-2-pyrrolidone can be added to the obtained polymer dope for the purpose of adjusting the polymer concentration and viscosity.

Next, the obtained para-type wholly aromatic copolyamide dope is used for yarn production.
First, the polymer dope is discharged from the spinneret. The hole diameter, nozzle length, number of holes, material, and the like of the spinneret used for discharging are not particularly limited, and can be appropriately adjusted in consideration of the fiber diameter, the number of single yarns, the spinnability, and the like of the obtained fiber. .
The temperature of the polymer dope when passing through the spinneret and the temperature of the spinneret are not particularly limited, but are preferably 80 to 120 ° C. from the viewpoint of spinnability and polymer dope discharge pressure.

  Next, the polymer dope discharged from the spinneret is coagulated in a coagulating liquid by a known semi-dry semi-wet spinning method. At this time, the length of the air gap is not particularly limited, but is preferably 5 to 15 mm from the viewpoints of temperature controllability and stringiness. The coagulating liquid used here is an NMP aqueous solution, and the temperature and NMP concentration are not particularly limited, and are adjusted as appropriate within a range in which there is no problem in the coagulation state of the yarn taken out and the subsequent process passability. be able to.

  Next, the solidified yarn is washed with water. The purpose of this washing step is to remove NMP in the yarn as much as possible using water. The washing conditions are not particularly limited, and the number and temperature of the washing bath can be appropriately adjusted within a range in which NMP in the yarn can be sufficiently removed.

Next, water-repellent silica fine particles are imparted to the washed yarn for the purpose of suppressing fusion between single fibers in the subsequent drying step and heat drawing step and imparting water repellency to the resulting fiber. . Also, the amount of the grant, finally it is necessary to 10mg ^{/ m 2} ~700mg ^/ m 2 adhered to the fiber. When the adhesion amount is less than 10 mg / m ^2, it is not preferable because sufficient water repellency cannot be imparted to the fiber. On the other hand, if it exceeds 700 mg / m ² , the amount of silica fine particles not in contact with the fiber surface increases, and this fiber is easily dropped off when using the fiber, causing scum generation. Note that even if water-repellent silica fine particles within the above range are applied in this step, there is a concern that the fine particles will inevitably fall off during the process until winding. Therefore, in anticipation that falling matter, the adhesion amount of the water-repellent silica particles is preferably 100mg ^{/ m 2} ~2,000mg ^/ m 2 in this step, more preferably ^{50mg / m 2 ~1,500mg / m 2} , and most preferably is ^{30mg / m 2 ~1,000mg / m 2} . The excessively applied water-repellent silica fine particles can be removed by spraying with compressed air or the like.

  Next, the fiber to which the water-repellent silica fine particles are adhered is dried. The drying conditions at this time are not particularly limited, and there is no problem as long as the moisture adhering to the fibers can be sufficiently removed. However, in consideration of workability and deterioration of the fibers due to heat, the temperature is 150 to 250 ° C. preferable. For drying, either a contact-type drying apparatus such as a roller or a non-contact type drying apparatus in which fibers pass through a drying furnace can be used.

  Next, the dried fiber is hot-drawn. In this step, the object is to highly orient polymer molecules in the fiber and impart strength by hot drawing of the fiber. The heat stretching temperature at this time is preferably 300 to 600 ° C, more preferably 320 ° C to 580 ° C, and most preferably 350 to 550 ° C. When the heat drawing temperature is less than 300 ° C., the yarn cannot be sufficiently drawn, which is not preferable. On the other hand, when the temperature exceeds 600 ° C., the polymer is deteriorated due to thermal decomposition, and a high-strength yarn cannot be obtained. The draw ratio in this hot drawing step is preferably 5 to 15 times, but is not particularly limited to this range as long as sufficient high strength can be achieved. Moreover, in this thermal stretching process, there is no particular problem even if it is performed in multiple stages as necessary.

Next, the water-repellent silica fine particles that are excessively applied in advance for the purpose of suppressing the fusion of the single fibers are removed. The removal of the water-repellent silica fine particles can be omitted if necessary, but the inorganic fine particles that are only adhered to the surface of the fiber in particular can affect the hue of the fiber and cause scum. Therefore, it is preferable to remove those that are excessively adhered. The removal method is not particularly limited, but excess water-repellent silica fine particles can be removed by spraying compressed air or the like. This condition, if finally 10mg ^{/ m 2} ~700mg ^/ m 2 deposited so to the fiber, is not particularly limited, can be appropriately adjusted.

  Then, if necessary, an oil agent is applied for the purpose of imparting charge suppression or lubricity to the fiber, and finally wound with a winder. There are no particular limitations on the type of oil agent to be applied and the amount to be applied, and the oil agent can be appropriately adjusted depending on the subsequent use. Moreover, about the winding method with a winder, it can wind up, adjusting a winding condition suitably using a well-known winder.

Para-type wholly aromatic copolyamide fibers of the present invention thus obtained, the fiber surface is covered by a water-repellent silica particles at a ratio of ^{10mg / m 2 ~700mg / m 2} , excellent water repellency, the fiber surface The critical surface tension is preferably 10 mN / m to 20 mN / m and the tensile strength is preferably 20 cN / dtex or more.

In order to set the critical surface tension of the fiber surface within the above range, for example, the water-repellent silica fine particles of the present invention may be attached to the fiber of the present invention within the above range.
The tensile strength of the fiber of the present invention is more preferably 22 to 25 cN / dtex. For example, the tensile strength of the para-type wholly aromatic copolyamide fiber can be controlled by controlling the draw ratio.

The physical property items used in the examples were measured as follows.
<Average particle diameter of fine particles (D50)>
Above

<Adhesion amount of inorganic (silica) fine particles on fiber surface>
The obtained fiber was pyrolyzed in an electric furnace under the following conditions, and the residue at that time was defined as the weight of inorganic fine particles adhering to the fiber surface, and this value and the surface area of the fiber were calculated from the following formula. The measurement results are shown in Table 1.
Temperature: 750 ° C
Time: 4 hours Silica fine particles adhering to the fiber (mg / m ² ) = weight of silica fine particles (mg) / fiber surface area (m ² )

<Critical surface tension of single fiber>
Under the following conditions, a liquid is dropped onto a single fiber, and the contact angle between the single fiber and each liquid is measured. From these results, the critical surface tension was calculated by the Zisman method. The Zisman method referred to here extends the straight line obtained by plotting cos θ on the horizontal axis and the surface tension of each liquid on the vertical axis when the contact angle (θ) is just after dropping the liquid onto the single fiber. The surface tension when cos θ = 1 (θ = 0) is read as the critical surface tension of the single fiber. The measurement results are shown in Table 1.
Temperature: Room temperature Solvent used: (1) Water (surface tension = 72 mN / m), (2) Glycerin (surface tension = 63 mN / m), (3) Hexadecane (surface tension = 30 mN / m)

<Scum on fiber>
The obtained fiber 1 m was rubbed with two fingers, and the amount of scum taken at that time was determined in three stages of ◯ / Δ / × according to the following criteria.
○: Scum does not adhere to the finger at all. Δ: Scum slightly adheres to the finger. ×: Scum clearly adheres to the finger. Table 1 shows the measurement results.

<Tensile strength of fiber>
In accordance with ASTM D885, the tensile strength, breaking elongation, and initial elastic modulus of the fiber were measured under the following conditions.
Temperature: Room temperature Tester: An INSTRON 5565 type (manufactured by INSTRON) was used to conduct a tensile test using a yarn test chuck.
Test piece: 75cm
Test speed: 250 mm / min Distance between chucks: 500 mm
The measurement results are shown in Table 1.

[Example 1]
Nitrogen was fed into a stirring tank having a stirring blade and sufficiently substituted, and then 35 parts by weight of paraphenylenediamine and 65 parts by weight of 3,4'-diaminodiphenyl ether were added. When the total amount of the added aromatic diamine was 100 mol%, the molar ratio of paraphenylene diamine and 3,4′-diaminodiphenyl ether was 50 mol%. Next, 2500 parts by weight of NMP was added, and the aromatic diamine was completely dissolved while stirring.

  After the aromatic diamine was completely dissolved, 130 parts by weight of terephthalic acid dichloride was added to carry out a polycondensation reaction. In addition, the addition amount of a terephthalic-acid dichloride is 100 mol% with respect to aromatic diamine. The reaction temperature and reaction time at this time were 80 ° C. and 30 minutes, respectively. By this polycondensation reaction, an aromatic copolyamide polymer was produced, and a polymer dope was obtained. Thereafter, for the purpose of neutralizing the polymer dope, 50 parts by weight of calcium hydroxide was added to the polymer dope to carry out a neutralization reaction, thereby obtaining an isotropic polymer dope used for yarn production. The polymer concentration of the obtained polymer dope was 6% by weight.

Next, a spinneret having a hole diameter of 0.3 mm and a hole number of 1,000 was heated to 105 ° C., and then the polymer dope heated to 105 ° C. was discharged, and the NMP concentration was 30 wt% through an air gap of 10 mm. And passed through a coagulation bath at 50 ° C. to obtain a coagulated yarn.
Subsequently, it is washed in a 50 ° C. water-washing bath, and thereafter, water-repellent silica fine particles (average particle size (D50) = 300 nm, SP-03F manufactured by Fuso Scientific Industry Co., Ltd.) are 2 wt. %.

Next, after drying with a 200 ° C. drying roller, the first stage of thermal stretching was performed at 380 ° C. The draw ratio at this time was 2.4 times. Subsequently, the second stage of thermal stretching was performed at 530 ° C. The draw ratio at this time was 4 times.
Thereafter, excessively attached water-repellent silica fine particles were removed with compressed air. The amount of the water-repellent silica fine particles attached to the fiber weight after passing through this step was 520 mg / m ² .

  Finally, the fiber was wound around a paper tube with a winder to obtain the fiber. In addition, the fineness of the fiber at this time was 1,670 dtex, and the number of fibers was 1,000. Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. The surface tension of the obtained fiber had a critical surface tension that was clearly smaller than that in the case where inorganic fine particles were not used in Comparative Examples described later. From this, it can be judged that this fiber has high water repellency. Further, since almost no scum on the fiber was observed, the water-repellent silica fine particles were strongly adhered to the fiber surface by an anchor effect or the like, and it can be expected that the decrease in water repellency with time can be suppressed.

[Example 2]
Fibers were obtained in the same manner as in Example 1 except that the water-repellent silica fine particles after water washing were adhered to 0.4% by weight with respect to the fiber weight. In addition, the adhesion amount of the water-repellent silica fine particles with respect to the fiber weight at this time was 73 mg / m ² . Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. Since the amount of water-repellent silica adhering to the fiber surface was smaller than in Example 1, the critical surface tension was slightly higher, but it was at a level with sufficiently high water repellency, and no scum on the fiber was observed.

[Comparative Example 1]
Fibers were obtained by the same method as in Example 1 except that the water-repellent silica fine particles after washing were adhered to 0.05% by weight with respect to the fiber weight. In addition, the adhesion amount of the water-repellent silica fine particles with respect to the fiber weight at this time was 7 mg / m ² . Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. Although no scum on the fiber was observed, the critical surface tension was almost the same as when water-repellent silica fine particles described later were not used. This is presumably because there was almost no contribution to the surface tension of the fiber because the amount of water-repellent silica fine particles deposited was too small.

[Comparative Example 2]
Fibers were obtained in the same manner as in Example 1 except that 5% by weight of water-repellent silica fine particles were adhered to the fiber weight after washing. In addition, the adhesion amount of the water-repellent silica fine particles with respect to the fiber weight at this time was 870 mg / m ² . Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. Although the critical surface tension was almost the same as when water-repellent silica fine particles described later were not used, a large amount of scum was observed on the fiber. This is preferable because the amount of water-repellent silica fine particles attached is too large, and this does not affect the water repellency, but when processing the resulting fiber, it causes scum and significantly reduces processing workability. Absent.

[Comparative Example 3]
In place of the water-repellent silica fine particles, talc fine particles (manufactured by Fuji Talc Kogyo Co., Ltd., commercial name: talc LMR # 200) (average particle diameter (D50) = 120 nm) are used, and this is used in the drying / hot stretching step A fiber was obtained in the same manner as in Example 1 except that it was used as an anti-fusing agent for single fibers. In addition, the adhesion amount of the talc fine particle with respect to the fiber weight at this time was 410 mg / m < ² >. Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. Although the critical surface tension was slightly higher than that of Comparative Example 6 described later without using fine particles, it was clearly higher than when water-repellent silica fine particles were used, and a fiber with high water repellency could not be obtained.

[Comparative Example 4]
A fiber was obtained in the same manner as in Example 1 except that the water-repellent silica fine particles were not used. Table 1 shows the measurement results of critical surface tension, scum on the fiber, and tensile strength of the obtained fiber. The critical surface tension is the highest value compared to other examples, and it is considered that high water repellency cannot be expected for the para-type wholly aromatic copolyamide polymer itself. In addition, as a result of cross-sectional observation of the fibers, many single fibers were fused together, which is considered to be due to the fact that no anti-fusing agent was used.

  The para-type wholly aromatic copolyamide fiber of the present invention is used for various industrial materials requiring high strength, high water repellency, high elastic modulus, high heat resistance, etc., for ropes and cables, and for protective clothing such as fire clothes. As particularly useful.

Claims (5)

A para-type wholly aromatic copolyamide fibers, para-type wholly aromatic repellency silica fine particles adhering to the para-type wholly aromatic copolyamide fiber surface at ^{10mg / m 2 ~700mg / m 2} , and the resulting Para-type wholly aromatic copolyamide fiber, wherein the critical surface tension of the group copolyamide fiber is 10 mN / m to 20 mN / m.   The para-type wholly aromatic copolyamide fiber according to claim 1, wherein the water-repellent silica fine particles have an average particle diameter (D50) of 10 nm to 500 nm.   The para type wholly aromatic copolyamide fiber according to claim 1 or 2, wherein the para type wholly aromatic copolyamide fiber has a tensile strength of 20 cN / dtex or more.   The para-type wholly aromatic copolyamide fiber according to any one of claims 1 to 3, wherein the para-type wholly aromatic copolyamide is copolyparaphenylene 3,4'-oxydiphenylene terephthalamide. The para-type wholly aromatic copolyamide polymer solution dissolved in the amide solvent is discharged from the die, and the water-repellent silica fine particles are adhered to the fiber after the coagulation step / water washing step, followed by the drying step and the heat stretching step, finally para-type wholly aromatic copolyamide water repellent silica particles 10mg ^{/ m 2} ~700mg ^/ m 2 adhered to the fiber surface, and para-critical surface tension of the wholly aromatic copolyamide fibers obtained is 10 mN / A method for producing a para-type wholly aromatic copolyamide fiber, wherein m to 20 mN / m.