JP6582980B2 - Fiber having phase separation structure and method for producing the same - Google Patents

Description

  The present invention relates to a fiber having a phase separation structure. More specifically, despite having a phase separation structure, the fineness spots are small, the occurrence of dyed spots and fluff is suppressed, and further, the durability of the fiber characteristics against long-term storage and tumbler drying, moisture absorption In particular, the present invention relates to a fiber that can be suitably used for apparel and has excellent antistatic properties in a low-temperature and low-humidity environment and suppresses elution of a hydrophilic compound during dyeing or use.

  Polyester fibers are used in a wide range of applications because they are inexpensive and have excellent mechanical properties. However, since it has poor hygroscopicity, it has drawbacks to be solved such as generation of stuffiness at high humidity in summer and generation of static electricity at low humidity in winter. The frictional voltage of polyethylene terephthalate, which is a general-purpose polyester, is about 7000 to 9000 V in a standard state at a temperature of 20 ° C. and a humidity of 40% RH. The smaller the value of the frictional voltage, the less likely to be charged with static electricity, and the better the wearing comfort. In the case of polyethylene terephthalate, it can be said that the fiber has extremely poor antistatic properties.

  In order to improve the above-mentioned drawbacks, various proposals have been made so far regarding methods for imparting antistatic properties to polyester fibers. Examples of a general method for imparting antistatic properties include copolymerization of a hydrophilic compound or addition of a hydrophilic compound to polyester. Although these methods can improve the anti-static property, sufficient anti-static property is required in low-temperature and low-humidity environments such as outdoors in winter and indoors where the humidity is extremely low due to the use of heating. The current situation is that it was not obtained.

  For example, Patent Document 1 proposes an antistatic polyester fiber in which polyoxyalkylene glycol and an organic metal salt are added as a hydrophilic compound to polyester. In this proposal, antistatic properties are imparted by dispersing polyoxyalkylene glycol in polyester fibers.

  Patent Document 2 proposes a core-sheath composite fiber having a polyester copolymerized with polyethylene glycol as a core and polypropylene terephthalate as a sheath. In this proposal, the antistatic property is imparted to the polyester fiber by the polyester copolymerized with polyethylene glycol disposed in the core.

Japanese Unexamined Patent Publication No. 7-173725 Japanese Unexamined Patent Publication No. 11-93022

  However, in the method described in Patent Document 1, although the frictional voltage is as low as 600 V at a temperature of 20 ° C. and a humidity of 40% RH and the antistatic property is good, the low temperature low such as a temperature of 10 ° C. and a humidity of 10% RH is low. There was a problem that sufficient antistatic property was not exhibited in a humidity environment. Further, since the polyester and the hydrophilic compound are not copolymerized, the hydrophilic compound is eluted at the time of dyeing or use, and there is a problem that the antistatic durability is low.

  Also in the method described in Patent Document 2, as in the method described in Patent Document 1, at a temperature of 20 ° C. and a humidity of 40% RH, the frictional band voltage is as low as 400 V and the antistatic property is good. There was a problem that sufficient antistatic properties were not exhibited in a low temperature and low humidity environment such as 10% RH.

  In any case, when polyethylene glycol incompatible with polyester is used as the hydrophilic compound, there is a problem that fineness spots are large and dyed spots and fluff are generated. Furthermore, since the oxidative degradation of polyethylene glycol is not suppressed, the oxidative degradation proceeds due to long-term storage and tumbler drying, and the fiber properties such as hygroscopicity, antistatic properties and mechanical properties in a low temperature and low humidity environment decrease. There was a problem.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and despite having a phase separation structure, the fineness spots are small, the occurrence of dyed spots and fluff is suppressed, and further, moisture absorption It is an object of the present invention to provide a fiber that can be suitably used for apparel applications, and has excellent antistatic properties in an environment and low temperature and low humidity environment, and the elution of a hydrophilic compound is suppressed during dyeing and use.

The above-mentioned problem of the present invention consists of a copolymer of a hydrophobic polymer and a hydrophilic polymer, has a continuous phase and a dispersed phase by a phase separation structure, and the maximum diameter of the dispersed phase in the fiber cross section is 1 to a 40 nm, fineness variation value U% (hi) is 0.1 to 1.5% der is, the hydrophobic polymer is a polyester, a phase separation structure wherein the hydrophilic polymer is Ru Ah with polyethylene glycol It can be solved by having fibers.

The fiber of the present invention is a copolymer of hydrophobic polymer and a hydrophilic polymer, it has preferably be exposed to at least a portion of the fiber surface.

  Furthermore, the fiber of the present invention was heated from room temperature to 160 ° C. at a mixed gas flow rate of 200 mL / min and a heating rate of 30 ° C./min in a mixed gas atmosphere of nitrogen: oxygen = 80 vol%: 20 vol%, and then 160 ° C. When differential thermogravimetric analysis (DTG) is performed under the conditions held in step 1, the time to reach 160 ° C. is 0 minute, and the time to the rising half-point is preferably 120 minutes or more. Moreover, it contains at least one antioxidant, and the antioxidant is at least one selected from phenolic compounds, sulfur compounds, and hindered amine compounds, and the antioxidant content is 0.01-2. 0% by weight can be suitably employed.

  Furthermore, the fiber of the present invention preferably has a frictional voltage of 3000 V or less measured at a temperature of 10 ° C. and a humidity of 10% RH based on JIS L1094.

Also preferred is a method for producing a fiber characterized by spinning so that a copolymer of a hydrophobic polymer and a hydrophilic polymer passes through a spinneret so that the shear rate is 10,000 to 40,000 s ^−1. Can be adopted.

  According to the present invention, despite having a phase separation structure, the fineness spots are small, the occurrence of dyed spots and fluff is suppressed, and further, the durability of the fiber properties against long-term storage and tumbler drying Further, it is possible to provide a fiber that is excellent in hygroscopicity and antistatic property in a low-temperature and low-humidity environment, and in which elution of the hydrophilic compound is suppressed during dyeing and use. This fiber can be suitably used particularly for clothing applications.

FIG. 1 is a drawing-substituting photograph illustrating a fiber cross section of a fiber having a phase separation structure of the present invention. FIG. 2 is a drawing-substituting photograph illustrating a fiber longitudinal section of a fiber having a phase separation structure of the present invention.

  The fiber of the present invention comprises a copolymer of a hydrophobic polymer and a hydrophilic polymer, has a continuous phase and a dispersed phase by a phase separation structure, and the maximum diameter of the dispersed phase in the fiber cross section is 1 to 40 nm. Yes, the fineness variation value U% (hi) is 0.1 to 1.5%. Although the fiber of the present invention has a phase separation structure, it forms a fine and uniform dispersed phase in the cross section of the fiber as shown in FIG. 1, so that fineness spots are small, and dyed spots and fluff are generated. Is suppressed. Also, by copolymerizing hydrophobic polymer and hydrophilic polymer, it is possible to impart hygroscopicity and antistatic properties to the fiber, and the elution of hydrophilic compounds is suppressed during dyeing and use. Therefore, it has durability in terms of hygroscopicity and antistatic properties. Further, as shown in FIG. 2, since a fine and uniform streaky dispersed phase is formed in a direction parallel to the fiber axis in the longitudinal section of the fiber, the frictional voltage is low even in a low temperature and low humidity environment, and the control is performed. It becomes possible to obtain a fiber having excellent electrical properties.

  The hydrophobic polymer in the present invention is not particularly limited as long as it can be copolymerized with the hydrophilic polymer, and can be suitably used. Specific examples of the hydrophobic polymer include aromatic polyesters such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polylactic acid, polyglycolic acid, polyethylene adipate, polypropylene adipate, polybutylene adipate, polyethylene succinate, Examples thereof include aliphatic polyesters such as polypropylene succinate, polybutylene succinate, polyethylene sebacate, polypropylene sebacate, polybutylene sebacate, and polycaprolactone, but are not limited thereto. Among these, polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate are preferable because they are excellent in mechanical properties and durability, and are easy to handle during production and use.

  The hydrophilic polymer in the present invention is not particularly limited as long as it can be copolymerized with a hydrophobic polymer, and can be suitably employed. By copolymerizing a hydrophilic polymer with a hydrophobic polymer, it becomes possible to impart antistatic properties to the fiber. Specific examples of the hydrophilic polymer include homopolymers such as polyethylene glycol and polypropylene glycol, copolymers such as polyethylene glycol-polypropylene glycol copolymer, polyethylene glycol-polybutylene glycol copolymer, and the like. It is not limited to. Of these, polyethylene glycol and polypropylene glycol are preferable because they are easy to handle during production and use.

  The fiber of the present invention is made of a copolymer of a hydrophobic polymer and a hydrophilic polymer. Unlike melt blending like polymer blends, hydrophobic polymer and hydrophilic polymer form a covalent bond by copolymerization, so the elution of the hydrophilic polymer from the fiber is suppressed, making it It is possible to obtain a fiber excellent in durability with little change in fiber characteristics between processes at the time or during use of a product.

  The fiber of the present invention has a phase separation structure. This phase separation structure is specifically expressed in the process in which the polymerization reaction proceeds and the hydrophobic polymer and the hydrophilic polymer are copolymerized. That is, unlike the phase separation structure expressed by melt mixing of incompatible polymer compounds, in the present invention, a fine and uniform dispersed phase is formed because the phase separation structure is developed as the polymerization reaction proceeds. Since the dispersed phase is fine and uniform, the resulting fibers have a phase separation structure, but the fineness spots are small, and the occurrence of dyed spots and fluff is suppressed. Moreover, since it has a phase separation structure, it is possible to obtain a fiber having excellent antistatic properties in a low temperature and low humidity environment.

  Specific examples of the phase separation that develops as the polymerization reaction proceeds are shown. In the case of a copolymer of polyethylene terephthalate as a hydrophobic polymer and polyethylene glycol as a hydrophilic polymer, the polarity of bis (β-hydroxyethyl) terephthalate, which is a precursor of polyethylene terephthalate, and polyethylene glycol are close to each other at the initial stage of the polycondensation reaction. Therefore, it is in a compatible state and the reaction system is transparent. As the polycondensation reaction proceeds, a polyethylene terephthalate-polyethylene glycol copolymer is formed, and after about 1 hour from the start of polymerization, a phase separation state occurs and the reaction system becomes cloudy. This phase-separated structure includes a polyethylene terephthalate-polyethylene glycol copolymer, a low polarity copolymer, that is, a copolymer having a high proportion of polyethylene terephthalate in the molecular chain, and a high polarity copolymer, that is, a molecular chain. A copolymer having a high proportion of polyethylene glycol in the interior is produced, and is expressed by the difference in polarity.

  The fiber of the present invention has a continuous phase and a dispersed phase due to a phase separation structure. The components constituting the continuous phase and the dispersed phase vary depending on the copolymerization ratio of the hydrophobic polymer and the hydrophilic polymer. When the proportion of the hydrophobic polymer is larger than that of the hydrophilic polymer, the “hydrophobic polymer-hydrophilic polymer copolymer” having a higher proportion of the hydrophobic polymer in the molecular chain becomes a continuous phase, A “hydrophobic polymer-hydrophilic polymer copolymer” having a high proportion of the hydrophilic polymer in the molecular chain becomes the dispersed phase. On the other hand, when the proportion of the hydrophilic polymer is larger than that of the hydrophobic polymer, the “hydrophobic polymer-hydrophilic polymer copolymer” having a high proportion of the hydrophilic polymer in the molecular chain is a continuous phase. Thus, a “hydrophobic polymer-hydrophilic polymer copolymer” having a high proportion of the hydrophobic polymer in the molecular chain becomes the dispersed phase. In either case, both the continuous phase and the dispersed phase are composed of a “hydrophobic polymer-hydrophilic polymer copolymer” and the composition ratio is different. Phase separation structure with extremely high properties. For this reason, it has been found that the stability of the dispersed phase during melt residence is extremely high, and a phase separation structure is formed in which the dispersed phase is difficult to coarsen during the melt residence. For this reason, it became clear that the fineness unevenness at the time of fiberizing by melt spinning was improved, and that elution of the hydrophilic compound could be suppressed during dyeing and use.

  In the present invention, when polyester is used as the hydrophobic polymer, an ester-forming dicarboxylic acid other than terephthalic acid may be used as the dicarboxylic acid component of the polyester. Specific examples of the ester-forming dicarboxylic acid include adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-lithium sulfoisophthalic acid, 5- (tetra Examples include, but are not limited to, dicarboxylic acids such as (alkyl) phosphonium sulfoisophthalic acid and ester-forming derivatives thereof.

  When polyester is used as the hydrophobic polymer in the present invention, an ester-forming diol other than ethylene glycol may be used as the diol component of the polyester. Specific examples of the ester-forming diol include, but are not limited to, propanediol, butanediol, hexanediol, cyclohexanediol, diethylene glycol, hexamethylene glycol, neopentyl glycol, and ester-forming derivatives thereof.

  In the present invention, when polyethylene terephthalate is used as the hydrophobic polymer and polyethylene glycol is used as the hydrophilic polymer, the number average molecular weight of polyethylene glycol is preferably 7,000 to 20,000. If the number average molecular weight of polyethylene glycol is 7000 or more, a phase separation structure is expressed by copolymerization with polyethylene terephthalate, and therefore, fibers having excellent antistatic properties can be obtained by fiberizing. The number average molecular weight of polyethylene glycol is more preferably 7500 or more, and further preferably 8000 or more. On the other hand, when the number average molecular weight of polyethylene glycol is 20000 or less, polycondensation reactivity between polyethylene terephthalate and polyethylene glycol is high, and unreacted polyethylene glycol can be reduced. In addition, by copolymerization with polyethylene terephthalate, a stable phase separation structure is formed in which the dispersed phase is fine and uniform, and coarsening during melt residence is suppressed, and discharge from the polycondensation tank after completion of the polycondensation reaction, It is preferable because the discharge from the spinneret is stable during spinning and the operability is improved. Furthermore, it is preferable because it is possible to obtain a homogeneous fiber with small fineness spots and suppressed generation of dyed spots and fluff. The number average molecular weight of polyethylene glycol is more preferably 17000 or less, and further preferably 15000 or less.

  In the present invention, when polyethylene terephthalate is used as the hydrophobic polymer and polyethylene glycol is used as the hydrophilic polymer, the copolymerization ratio of polyethylene glycol is preferably 10 to 20% by weight. If the copolymerization ratio of polyethylene glycol is 10% by weight or more, fibers excellent in hygroscopicity and antistatic properties can be obtained, which is preferable. The copolymerization rate of polyethylene glycol is more preferably 11% by weight or more, and further preferably 12% by weight or more. On the other hand, if the copolymerization ratio of polyethylene glycol is 20% by weight or less, a fine and uniform phase separation structure is formed by copolymerization with polyethylene terephthalate, and after discharging from the polycondensation tank after spinning reaction or spinning, It is preferable because discharge from the spinneret is stable and operability is improved. In addition, it is preferable because homogeneous fibers with small fineness spots and suppressed generation of dyed spots and fluff can be obtained, and the mechanical properties of the fibers and the fiber structure composed thereof are favorable. The copolymerization ratio of polyethylene glycol is more preferably 19% by weight or less, and further preferably 18% by weight or less.

  In the present invention, as a result of intensive studies on the phase separation structure composed of a hydrophobic polymer (polyethylene terephthalate) -hydrophilic polymer (polyethylene glycol) copolymer, as described above, the inventors have determined that the affinity between the continuous phase and the dispersed phase is as described above. Since the phase separation structure is extremely high, when the shear is applied in the molten state, the phase separation structure is finely dispersed and eventually disappears, but when the application of the shear is stopped and a certain time elapses, the phase separation structure appears again. I found a peculiar phenomenon. Although described in detail in the fiber manufacturing method described later, by utilizing this unique phenomenon, fineness spots are small and the occurrence of dyed spots and fluff is suppressed despite having a phase separation structure. Succeeded in obtaining a good fiber.

  The copolymer of the hydrophobic polymer and the hydrophilic polymer in the present invention may have been subjected to various modifications by adding secondary additives. Specific examples of secondary additives include compatibilizers, plasticizers, UV absorbers, infrared absorbers, fluorescent brighteners, mold release agents, antibacterial agents, nucleating agents, thermal stabilizers, antioxidants, and charging Examples include, but are not limited to, inhibitors, anti-coloring agents, regulators, matting agents, antifoaming agents, preservatives, gelling agents, latexes, fillers, inks, coloring agents, dyes, pigments, and fragrances. These secondary additives may be used alone or in combination.

  The maximum diameter of the dispersed phase in the fiber cross section of the fiber of the present invention is 1 to 40 nm. Details of the method for measuring the maximum diameter of the dispersed phase in the fiber cross section will be described later. When the maximum diameter of the dispersed phase in the fiber cross section is 1 nm or more, a fiber excellent in hygroscopicity and antistatic property can be obtained. The maximum diameter of the dispersed phase in the fiber cross section is more preferably 3 nm or more, further preferably 5 nm or more, and particularly preferably 10 nm or more. On the other hand, when the maximum diameter of the dispersed phase in the fiber cross section is 40 nm or less, the mechanical properties of the fiber and the fiber structure formed thereof are good and the durability is excellent. Further, since it is a fine and uniform dispersed phase, the ejection from the spinneret becomes stable during spinning, the operability is good, the fineness spots are small, and the occurrence of dyed spots and fluff is suppressed. The maximum diameter of the dispersed phase in the fiber cross section is more preferably 37 nm or less, still more preferably 35 nm or less, and particularly preferably 30 nm or less.

  The maximum diameter of the dispersed phase in the fiber longitudinal section of the fiber of the present invention is preferably 1 to 40 nm. Details of the method for measuring the maximum diameter of the dispersed phase in the fiber longitudinal section will be described later. The maximum diameter of the dispersed phase in the fiber longitudinal section is the maximum value of the diameter of the dispersed phase with respect to the direction perpendicular to the fiber axis. If the maximum diameter of the dispersed phase in the longitudinal section of the fiber is 1 nm or more, it is preferable because a fiber excellent in hygroscopicity and antistatic property can be obtained. The maximum diameter of the dispersed phase in the longitudinal section of the fiber is more preferably 3 nm or more, further preferably 5 nm or more, and particularly preferably 10 nm or more. On the other hand, if the maximum diameter of the dispersed phase in the fiber longitudinal section is 40 nm or less, it is preferable because the mechanical properties of the fiber and the fiber structure composed thereof are good and the durability is excellent. Moreover, since it is a fine and uniform dispersed phase, discharge from the spinneret is stable during spinning, operability is good, fineness spots are small, and generation of dyed spots and fluff is suppressed, which is preferable. The maximum diameter of the dispersed phase in the fiber longitudinal section is more preferably 37 nm or less, still more preferably 35 nm, and particularly preferably 30 nm or less.

  The total fineness of the fiber of the present invention is not particularly limited and can be appropriately selected according to the application and required characteristics, but is preferably 10 to 500 dtex. If the total fineness of the fiber is 10 dtex or more, it is preferable because the yarn breakage is small and the process passability is good, the generation of fluff is small during use, and the durability is excellent. The total fineness of the fiber is more preferably 30 dtex or more, and further preferably 50 dtex or more. On the other hand, if the total fineness of the fibers is 500 dtex or less, the flexibility is not impaired when the fibers and fiber structures are formed. The total fineness of the fiber is more preferably 400 dtex or less, and further preferably 300 dtex or less.

  The strength of the fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is preferably 2.0 to 5.0 cN / dtex from the viewpoint of mechanical characteristics. If the strength of the fiber is 2.0 cN / dtex or more, there are few yarn breaks in the spinning, drawing process, weaving, knitting process, etc., in addition to good process passability, and excellent durability during use. preferable. The strength of the fiber is more preferably 2.5 cN / dtex or more, and further preferably 3.0 cN / dtex or more. On the other hand, if the strength of the fiber is 5.0 cN / dtex or less, the flexibility is not impaired when the fiber and the fiber structure are formed.

  The elongation of the fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is preferably 10 to 60% from the viewpoint of process passability. If the elongation of the fiber is 10% or more, the abrasion resistance of the fiber and the fiber structure is good, and the process passability is good. In addition, the occurrence of fluff is small during use, and the durability is good. Therefore, it is preferable. The elongation of the fiber is more preferably 15% or more, and further preferably 20% or more. On the other hand, if the elongation of the fiber is 60% or less, it is preferable because the dimensional stability of the fiber and the fiber structure becomes good. The elongation of the fiber is more preferably 55% or less, and further preferably 50% or less.

  The initial tensile resistance of the fiber of the present invention is not particularly limited, and can be appropriately selected according to the use and required characteristics. However, the initial tensile resistance measured according to 8.10 of JIS L1013: 1999 is 10 It is preferably ˜100 cN / dtex. If the initial tensile resistance of the fiber is 10 cN / dtex or more, the process passability and handleability are good, and the mechanical properties are excellent, which is preferable. The initial tensile resistance of the fiber is more preferably 15 cN / dtex or more, and further preferably 20 cN / dtex or more. On the other hand, if the initial tensile resistance of the fiber is 100 cN / dtex or less, the flexibility of the fiber and the fiber structure is not impaired, which is preferable. The initial tensile resistance of the fiber is more preferably 90 cN / dtex or less, and further preferably 80 cN / dtex or less.

  The fiber diameter of the fiber of the present invention is not particularly limited and can be appropriately selected according to the use and required characteristics, but is preferably 3 to 100 μm. If the fiber diameter is 3 μm or more, it is preferable because the yarn-manufacturing operability and process passability in high-order processing are good, and fibers having excellent mechanical properties can be obtained. The fiber diameter of the fiber is more preferably 5 μm or more, and further preferably 7 μm or more. On the other hand, a fiber diameter of 100 μm or less is preferable because the flexibility of the fiber and the fiber structure is not impaired. The fiber diameter of the fiber is more preferably 70 μm or less, and further preferably 50 μm or less.

  The boiling water shrinkage of the fiber of the present invention is preferably 3 to 15%. If the boiling water shrinkage of the fiber is 3% or more, it is preferable because the weaving density can be increased by heat shrinking the fabric, and the weaving tension in the weaving process can be suppressed to an appropriate range to produce a high-density fabric. . Furthermore, it is not necessary to weave under high tension when producing a high-density fabric, it is possible to suppress the occurrence of fluff and sink marks in the weaving process, and it is preferable because a fabric with few defects can be produced with good processability. . The boiling water shrinkage of the fiber is more preferably 4% or more, and further preferably 5% or more. On the other hand, if the boiling water shrinkage of the fiber is 15% or less, the orientation degree of the molecular chain is not extremely reduced during the treatment with boiling water, and the strength reduction after the boiling water treatment is small, which is preferable. Further, it is preferable because the fiber can be sufficiently contracted by a process of thermally contracting the fabric, and a flexible fabric can be obtained. The boiling water shrinkage of the fiber is more preferably 12% or less, and still more preferably 10% or less.

  The fineness variation value U% (hi) of the fiber of the present invention is 0.1 to 1.5%. The fineness variation value U% is an index of thickness variation in the fiber longitudinal direction, and the smaller the fineness variation value U% (hi), the smaller the thickness variation in the longitudinal direction of the fiber. The fineness fluctuation value U% (hi) is preferably as small as possible from the viewpoint of process passability and quality, but the lower limit is 0.1% as a manufacturable range. On the other hand, if the fiber fineness variation value U% (hi) is 1.5% or less, the uniformity in the longitudinal direction of the fiber is excellent, and fluctuations in processing tension are suppressed in the warping process, weaving, knitting process, etc. This is preferable because it can be performed. Furthermore, fluff and thread breakage are less likely to occur, and defects such as dyed spots and dyed streaks are less likely to occur when dyed, and a high-quality fiber structure can be obtained. The fineness variation value U% (hi) of the fiber is more preferably 1.2% or less, still more preferably 1.0% or less, and particularly preferably 0.9% or less.

  The single yarn diameter CV% of the fiber of the present invention is preferably 0.1 to 15%. The single yarn diameter CV% is preferably as small as possible from the viewpoint of process passability and quality, but the lower limit is 0.1% as a manufacturable range. On the other hand, if the single yarn diameter CV% of the fiber is 15% or less, generation of fluff can be suppressed during production and use, and defects such as dyed spots and dyed streaks are less likely to occur when dyed, This is preferable because a high-quality fiber structure can be obtained. The single yarn diameter CV% of the fiber is more preferably 12% or less, still more preferably 10% or less, and particularly preferably 7% or less.

  The single yarn fineness CV% of the fiber of the present invention is preferably 0.1 to 15%. The single yarn fineness CV% is preferably as small as possible from the viewpoint of process passability and quality, but 0.1% is the lower limit as a manufacturable range. On the other hand, if the single yarn fineness CV% of the fiber is 15% or less, the generation of fluff can be suppressed during production and use, and defects such as dyed spots and dyed streaks are less likely to occur when dyed, This is preferable because a high-quality fiber structure can be obtained. The single yarn fineness CV% of the fiber is more preferably 12% or less, still more preferably 10% or less, and particularly preferably 7% or less.

  The single yarn strength CV% of the fiber of the present invention is preferably 0.1 to 20%. The single yarn strength CV% is preferably as small as possible from the viewpoint of process passability and quality, but the lower limit is 0.1% as a manufacturable range. On the other hand, if the single yarn strength CV% of the fiber is 20% or less, the generation of fluff can be suppressed during production and use, and defects such as dyed spots and dyed streaks are less likely to occur when dyed, This is preferable because a high-quality fiber structure can be obtained. The single yarn strength CV% of the fiber is more preferably 15% or less, still more preferably 12% or less, and particularly preferably 10% or less.

  The single yarn elongation CV% of the fiber of the present invention is preferably 0.1 to 40%. The single yarn elongation CV% is preferably as small as possible from the viewpoint of process passability and quality, but the lower limit is 0.1% as a manufacturable range. On the other hand, if the single yarn elongation CV% of the fiber is 40% or less, generation of fluff can be suppressed during production and use, and defects such as dyed spots and dyed streaks are less likely to occur when dyed. Since a high-quality fiber structure can be obtained, it is preferable. The single yarn elongation CV% of the fiber is more preferably 37% or less, still more preferably 35% or less, and particularly preferably 30% or less.

  The fiber of the present invention was maintained at 160 ° C. after being heated from room temperature to 160 ° C. at a mixed gas flow rate of 200 mL / min and a heating rate of 30 ° C./min in a mixed gas atmosphere of nitrogen: oxygen = 80 vol%: 20 vol%. In differential thermogravimetric analysis (DTG), it is preferable that the time to reach 160 ° C. is 0 minute, and the time to the rising half-value point is 120 minutes or more. Although the details of the method for measuring the rising half-value point will be described later, this evaluation method was adopted as an accelerated test assuming durability against long-term storage and tumbler drying. The present inventors have performed differential thermogravimetric analysis (DTG) at 160 ° C. on fibers having a phase separation structure composed of a hydrophobic polymer (polyethylene terephthalate) -hydrophilic polymer (polyethylene glycol) copolymer in the present invention. The rising peak at is due to the degradation of the hydrophilic polymer (polyethylene glycol), and with the degradation of this polyethylene glycol, the hygroscopicity is lost, the difference in moisture absorption (ΔMR) is reduced, and further in a low temperature and low humidity environment. It has been confirmed that the anti-static property at is lost and the frictional voltage increases. The longer the time to the rising half-value point is, the longer it is from the viewpoint of durability of fiber properties such as hygroscopicity, antistatic properties in a low temperature and low humidity environment, and mechanical properties against long-term storage and tumbler drying. The time to the rising half-value point is more preferably 180 minutes or more, further preferably 240 minutes or more, and particularly preferably 360 minutes or more.

  The difference in moisture absorption (ΔMR) of the fiber of the present invention is preferably 1 to 10%. The details of the measurement method of MR will be described later, but the moisture absorption rate at a temperature of 30 ° C. and a humidity of 90% RH assuming the temperature and humidity in the clothes after light exercise, and the outside air temperature humidity at a temperature of 20 ° C. and a humidity of 65% RH The difference in moisture absorption is ΔMR. That is, ΔMR is a hygroscopic index, and the higher the value of ΔMR, the better the wearing comfort. If the ΔMR of the fibers is 1% or more, it is preferable because the feeling of stuffiness in the clothes is small and wearing comfort is expressed. The ΔMR of the fiber is more preferably 1.5% or more, and further preferably 2% or more. On the other hand, if the ΔMR of the fiber is 10% or less, the process passability and handleability are good, and the durability during use is excellent, which is preferable. The ΔMR of the fiber is more preferably 9% or less, and further preferably 8% or less.

  Since the fiber of the present invention is a copolymer of a hydrophobic polymer and a hydrophilic polymer, the hydrophilic polymer to hot water or the like is different from the case where the hydrophobic polymer and the hydrophilic polymer are melt-mixed. Elution is suppressed. Therefore, hygroscopic durability is high and can be suitably employed as a fiber structure.

  The fiber of the present invention preferably has a frictional voltage of 3000 V or less at a temperature of 10 ° C. and a humidity of 10% RH. Although details of the method for measuring the frictional voltage will be described later, the frictional voltage is an antistatic index, and the lower the value of the frictional voltage, the more the generation of static electricity is suppressed. The frictional voltage is preferably as small as possible from the viewpoint of wearing comfort. Furthermore, it is not only in a temperature and humidity environment such as a temperature of 20 ° C. and a humidity of 40% RH, but also at a low temperature such as a temperature of 10 ° C. and a humidity of 10% RH. It is preferable that the frictional voltage is low in a humidity environment and exhibits excellent antistatic properties. If the friction band voltage of the fiber at a temperature of 10 ° C and a humidity of 10% RH is 3000 V or less, there is little generation of static electricity even in low-temperature and low-humidity environments such as outdoors in winter and indoors where the humidity has become very low due to the use of heating. It is preferable because it is excellent in wearing comfort. The friction band voltage of the fiber at a temperature of 10 ° C. and a humidity of 10% RH is more preferably 2500 V or less, and further preferably 2000 V or less.

  The fiber of the present invention can be a composite fiber made of a copolymer of a hydrophobic polymer and a hydrophilic polymer and other (co) polymers other than this. At this time, the copolymer of the hydrophobic polymer and the hydrophilic polymer is preferably exposed on at least a part of the fiber surface. For example, a fiber in which a copolymer of a hydrophobic polymer and a hydrophilic polymer is used as a core component of a core-sheath composite fiber and is completely covered with a sheath component, or a copolymer of a hydrophobic polymer and a hydrophilic polymer Compared to the fiber that is completely covered with the sea component as the island component of the sea-island composite fiber, the one where the copolymer of the hydrophobic polymer and the hydrophilic polymer is exposed on at least a part of the fiber surface, It is preferable because a fiber excellent in hygroscopicity and antistatic property can be obtained. Even when a copolymer of a hydrophobic polymer and a hydrophilic polymer is used as the core component of the core-sheath composite fiber, it is sufficient that at least a part of the core component is exposed on the fiber surface. Even when a copolymer of a polymer and a hydrophilic polymer is used as the island component of the sea-island composite fiber, it is sufficient that at least a part of the island component is exposed on the fiber surface.

  The fiber of the present invention preferably contains an antioxidant. By containing an antioxidant, not only suppresses the oxidative degradation of hydrophilic polymers due to long-term storage and tumbler drying, but also the properties of fibers such as hygroscopicity, antistatic properties in low temperature and low humidity environments, and mechanical properties. Since durability improves, it is preferable. In addition, the inventors of the present invention have a uniform structure in which a fiber having a phase separation structure composed of a hydrophobic polymer (polyethylene terephthalate) -hydrophilic polymer (polyethylene glycol) copolymer in the present invention does not have a phase separation structure. In order to solve the problem of high oxidative decomposability compared to the fiber made of polyethylene terephthalate-polyethylene glycol copolymer, a method that can contain a sufficient amount of antioxidant in the fiber was found as described later, and phase separation was performed. While having the structure, oxidative degradation is suppressed, and it has become possible to stably obtain fibers with excellent fiber characteristics such as hygroscopicity, antistatic properties in low temperature and low humidity environments, and mechanical properties. .

  The antioxidant in the present invention is preferably selected from phenol compounds, sulfur compounds, and hindered amine compounds. These antioxidants may use only 1 type and may use 2 or more types together.

  The phenolic compound in the present invention is a radical chain reaction inhibitor having a phenol structure. Specific examples thereof include 2,6-t-butyl-p-cresol, butylhydroxyanisole, and 2,6-t-butyl-4. -Ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis {1,1-dimethyl-2- {β- (3- t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,8,10-tetraoxaspiro {5,5} undecane, 1 , 1,3-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl- 4-hydroxybenzyl) benzene, bis {3,3′-bis- (4′-hydroxy-3′-t-butylphenyl) butyric acid} glycol ester, tocopherol, pentaerythritol-tetrakis (3- (3,5 -Di-t-butyl-4-hydroxyphenol) propionate), 2,4,6-tris (3 ', 5'-di-t-butyl-4'-hydroxybenzyl) mesitylene, 1,3,5-tris [[4- (1,1-Dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione Etc. including but not limited to. These phenol compounds may be used alone or in combination of two or more. Among them, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010), 2,4,6-tris (3 ′, 5′-di) -T-butyl-4'-hydroxybenzyl) mesitylene (ADEKA, ADK STAB AO-330), 1,3,5-tris [[4- (1,1-dimethylethyl) -3-hydroxy-2,6- [Dimethylphenyl] methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione (manufactured by Tokyo Chemical Industry Co., Ltd., THANOX 1790) has a high oxidative degradation inhibitory effect and can be suitably employed. .

  The sulfur-based compound in the present invention is a sulfur-based antioxidant that reduces peroxide without generating radicals and oxidizes itself. Specific examples thereof include dilauryl 3,3′-thiodipropionate, dimyristyl. Examples include, but are not limited to, 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate. These sulfur type antioxidants may use only 1 type, and may use 2 or more types together.

  The hindered amine compound in the present invention is a hindered amine antioxidant that has an effect of trapping radicals generated by ultraviolet rays or heat and regenerating a phenolic antioxidant deactivated by functioning as an antioxidant. Dibutylamine-1,3,5-triazine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2, 6,6-tetramethyl-4-piperidyl) butylamine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl } {(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], N, N ′, N ′ ' N ′ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4, Polymer of 7-diazadecane-1,10-diamine, dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, poly [(6-morpholino-s-triazine-2, 4-diyl) [2,2,6,6-tetramethyl-4-piperidyl] imino] -hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]), poly [(6 -Morpholino-s-triazine-2,4-diyl) [2,2,6,6-tetramethyl-4-piperidyl] imino] -hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) ) Imino 1,6-hexanediamine-N, N′-bis (1,2,2,6,6-pentamethyl-4-piperidyl) and morpholine-2,4,6-trichloro-1,3,5- Methylated polymer of triazine, 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-20 (2,3-epoxy-propyl) dispiro- [5,1,11,2]- Examples include, but are not limited to, polymers of heneicosan-21-one. These hindered amine compounds may be used alone or in combination of two or more. Especially, it is preferable that it is a high molecular weight type | mold hindered amine type compound with a molecular weight of 1000 or more from a viewpoint of suppressing the elution from the inside of a fiber by washing or the cleaning which uses an organic solvent. In particular, dibutylamine-1,3,5-triazine-N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2, A 6,6-tetramethyl-4-piperidyl) butylamine polycondensate (CHIMASSORB2020 manufactured by BASF) has a high oxidative degradation inhibitory effect and can be suitably employed.

  The content of the antioxidant in the fiber of the present invention is preferably 0.01 to 2.0% by weight of the fiber weight. By containing a sufficient amount of antioxidant in the fiber to exhibit the antioxidant effect, it is possible to suppress oxidative degradation of hydrophilic compounds due to long-term storage and tumbler drying, hygroscopic, low temperature and low humidity environment It is preferable because durability of fiber properties such as antistatic properties and mechanical properties below is improved. If the content of the antioxidant is 0.01% by weight or more, the effect of suppressing oxidative degradation can be imparted to the fiber, which is preferable. The content of the antioxidant is more preferably 0.05% by weight or more, further preferably 0.1% by weight or more, and particularly preferably 0.15% by weight or more. On the other hand, if the content of the antioxidant is 2.0% by weight or less, the color tone of the fiber is not deteriorated, and the mechanical properties are not impaired. The content of the antioxidant is more preferably 1.7% by weight or less, further preferably 1.5% by weight or less, and particularly preferably 1.0% by weight or less.

  The fiber of the present invention is not particularly limited with respect to the cross-sectional shape of the fiber, and may be a perfect circular circular cross section or a non-circular cross section. Specific examples of non-circular cross sections include, but are not limited to, multi-leaf, polygon, flat, oval, C-shaped, H-shaped, S-shaped, T-shaped, W-shaped, X-shaped, Y-shaped, etc. Not.

  The fiber of the present invention is not particularly limited with respect to the form of the fiber, and may be any form such as monofilament, multifilament, and staple.

  The fibers of the present invention can be processed into false twists and twisted yarns in the same manner as general fibers, and weaving and knitting can be handled in the same manner as general fibers.

  The form of the fiber structure comprising the fibers of the present invention is not particularly limited, and can be made into a woven fabric, a knitted fabric, a pile fabric, a nonwoven fabric, a spun yarn, a stuffed cotton, or the like according to a known method. Further, the fiber structure composed of the fibers of the present invention may be any woven or knitted structure, such as plain weave, twill weave, satin weave, or these changed weaves, warp knitting, weft knitting, circular knitting, lace knitting or These change knitting can be suitably employed.

  The fiber of the present invention may be combined with other fibers by knit or knitting when making a fiber structure, or may be made into a fiber structure after blended yarn with other fibers.

  Next, a method for producing a copolymer of a hydrophobic polymer and a hydrophilic polymer used in the present invention will be described. As a specific example, a method for producing a phase separation structure composed of a polyester-polyethylene glycol copolymer using polyester as a hydrophobic polymer and polyethylene glycol as a hydrophilic polymer is shown below.

  In the present invention, when producing a polyester-polyethylene glycol copolymer, first, a polyester component alone is subjected to esterification or transesterification to obtain a polyester oligomer. Next, the polyester oligomer is added to a reaction vessel to which polyethylene glycol has been added in advance. In this case, when the polyethylene glycol is solid, it is preferably heated and melted at 70 ° C. or higher, and after adding the polyester oligomer to the polyethylene glycol, it is preferable to sufficiently stir. By doing so, in addition to improving the polycondensation reactivity of polyethylene glycol, the diffusion of polyethylene glycol into the polyester oligomer proceeds rapidly, and when the phase separation structure develops as the polycondensation reaction proceeds, In addition, it is possible to form a stable dispersed phase that is uniform and suppressed from coarsening during melt residence. In order to reduce unreacted polyethylene glycol, it is necessary that the polyester oligomer and polyethylene glycol are mixed and stirred for at least 1 hour or more in a compatible state. In the phase-separated structure comprising the obtained polyester-polyethylene glycol copolymer, if the dispersed phase is fine and uniform, and coarsening during melt residence is suppressed, fineness spots are small when fiberized by melt spinning. , The occurrence of dyed spots and fluff is suppressed. On the contrary, if polyethylene glycol is added into the molten polyester oligomer, the polyethylene glycol having a low specific gravity relative to the polyester is localized in the upper layer in the reaction vessel, and the polyethylene glycol diffuses into the polyester oligomer. It took quite a while. For this reason, the reaction rate of polyethylene glycol and polyester falls, and unreacted polyethylene glycol finally remains. In such a case, the dispersed phase tends to coarsen during melt residence and not only causes fineness spots when fiberized by melt spinning, but also the polyethylene glycol component of the hydrophilic polymer is eluted during dyeing and use. Care is required because it becomes easy and the durability of hygroscopicity and antistatic property decreases.

  In this invention, the general catalyst at the time of manufacturing polyester can be used in any of esterification reaction, transesterification reaction, and polycondensation reaction. The esterification reaction proceeds even without a catalyst, but a titanium compound or the like may be added as a catalyst. Specific examples of the transesterification catalyst include, but are not limited to, compounds such as magnesium, manganese, calcium, cobalt, zinc, lithium, and titanium. Specific examples of the polycondensation reaction catalyst include, but are not limited to, compounds such as antimony, titanium, and germanium.

  In the present invention, a phosphorus compound may be added as a heat stabilizer in order to improve the heat resistance and color tone of the fiber. Specific examples of the phosphorus compound include phosphoric acid compounds, phosphorous acid compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. These phosphorus compounds may be used alone or in combination.

  In the present invention, the phosphorus compound can be added as a heat stabilizer at any stage for producing the polyester-polyethylene glycol copolymer, and may be added at any stage before or after the esterification reaction or before or after the transesterification reaction. . In order to further improve the heat resistance and color tone, it is possible to reduce the pressure in the reaction vessel after adding the polycondensation catalyst and add a phosphorus compound additionally between the start and end of the polycondensation reaction. Good. When this heat stabilizer is not added, the molecular weight of the polyethylene glycol, which is a hydrophilic polymer, is lowered, the melt retention stability of the dispersed phase is lowered, and this becomes a factor of worsening fineness spots when fiberized by melt spinning.

  In the present invention, an antioxidant can be added at any stage. Before and after the esterification reaction, before and after the transesterification reaction, and after adding the polycondensation catalyst, the pressure in the reaction tank is reduced and the polycondensation reaction is started. It may be added at any stage until completion. When the polycondensation reaction is added between the start and the end of the polycondensation reaction, the inside of the polycondensation reaction tank may be under reduced pressure or normal pressure. As described above, the fiber having a phase-separated structure composed of a polyester-polyethylene glycol copolymer in the present invention is more oxidatively decomposable than a fiber composed of a polyester-polyethylene glycol copolymer having a uniform structure that does not have a phase-separated structure. Therefore, it is preferable to contain a sufficient amount of an antioxidant in the fiber. During the polycondensation reaction, the deactivation of the antioxidant due to thermal decomposition during the esterification reaction, transesterification reaction, or polycondensation reaction. From the viewpoint of preventing the antioxidant from scattering under reduced pressure, it is preferable to add an antioxidant just before the end of the polycondensation reaction and to stir the polycondensation reaction tank at normal pressure.

  In the present invention, in order to increase the molecular weight of the hydrophobic polymer (polyester) -hydrophilic polymer (polyethylene glycol) copolymer, solid phase polymerization may be performed using the copolymer obtained by the above method. Good. There are no particular restrictions on the solid-state polymerization apparatus and method, but the heat treatment is performed under an inert gas atmosphere or under reduced pressure. Specific examples of the inert gas include, but are not limited to, nitrogen, helium, carbon dioxide gas, and the like. When the pressure is reduced, the pressure in the apparatus is preferably set to 133 Pa or less, and further, the time required for the solid phase polymerization reaction can be shortened by lowering the pressure. It is preferable that the processing temperature of a solid phase polymerization is 150-240 degreeC. A treatment temperature of solid-phase polymerization of 150 ° C. or higher is preferable because the polymerization reaction proceeds and the molecular weight can be increased. The treatment temperature of the solid phase polymerization is more preferably 170 ° C. or higher, and further preferably 190 ° C. or higher. On the other hand, if the processing temperature of solid phase polymerization is 240 ° C. or lower, it is preferable because thermal decomposition can be suppressed and molecular weight reduction and coloring can be suppressed. The treatment temperature of the solid phase polymerization is more preferably 235 ° C. or less, and further preferably 230 ° C. or less.

  Another specific example of the method for producing the above-described hydrophobic polymer (polyester) -hydrophilic polymer (polyethylene glycol) copolymer will be described. By esterification reaction of terephthalic acid and ethylene glycol, or ester exchange reaction of dimethyl terephthalate and ethylene glycol, an oligomer of bis (β-hydroxyethyl) terephthalate (hereinafter referred to as BHT) in the esterification reaction vessel or transesterification reaction vessel. Is also synthesized). When BHT is transferred from the reaction vessel to a polycondensation reaction vessel heated to 250 to 270 ° C. through a transfer pipe, polyethylene glycol that has been heated and melted in advance is introduced into the polycondensation reaction vessel, and BHT is transferred thereto. Thereafter, the polyethylene glycol is sufficiently diffused into the BHT by stirring for about 1 hour. Subsequently, a polycondensation catalyst is added, the pressure is reduced to 500 Pa or less, and a polyethylene terephthalate-polyethylene glycol copolymer can be obtained by reacting at 260 to 300 ° C. for 3 to 5 hours.

  The phase separation structure composed of the hydrophobic polymer (polyethylene terephthalate) -hydrophilic polymer (polyethylene glycol) copolymer has a low polarity as the polycondensation reaction between polyethylene terephthalate precursor BHT and polyethylene glycol proceeds. Copolymer, that is, a copolymer having a high proportion of polyethylene terephthalate in the molecular chain, and a highly polar copolymer, that is, a copolymer having a high proportion of polyethylene glycol in the molecular chain. It is expressed by the difference in polarity. The size of the dispersed phase in the phase separation structure is controlled by the number average molecular weight and copolymerization rate of polyethylene glycol, the temperature and stirring speed of the polycondensation reaction, or the polymerization degree (molecular weight) of the polyethylene terephthalate-polyethylene glycol copolymer. Is possible.

  As a method for producing the fiber of the present invention, a known melt spinning method can be used. However, the copolymer of the hydrophobic polymer and the hydrophilic polymer of the present invention forms a phase separation structure, and the yarn is produced. Since the range that can be selected as the conditions is narrow, it is necessary to appropriately set the spinning conditions according to the characteristics of the copolymer of the hydrophobic polymer and the hydrophilic polymer. However, according to a specific example of the production method described later, it is possible to stably obtain fibers in which fineness spots are small and generation of dyed spots and fluff is suppressed despite having a phase separation structure.

  In general, in an incompatible polymer blend or polymer alloy system, immediately after the polymer is discharged from the spinneret, the spinning line bulges due to the ballast effect, and the thinning behavior tends to become unstable. In extreme cases, fiberization may not be possible. Also, the resulting fibers have large fineness spots and are of low quality due to the occurrence of dyed spots and fluff. Regarding the method for reducing the swollenness of the spinning line due to the ballast effect, as described in Japanese Patent Application Laid-Open No. 2009-79318, improvement in discharge stability due to a decrease in discharge linear velocity and shear rate, As described in Japanese Patent No. 202289, improvement in compatibility by adding a compatibilizing agent is well known. Since the copolymer of the hydrophobic polymer and the hydrophilic polymer of the present invention also forms a phase separation structure, the discharge linear velocity and shear rate are reduced for the purpose of suppressing the swell of the spinning wire due to the ballast effect. However, the discharge from the spinneret was unstable, and the resulting fibers had large fineness spots, and many dyed spots and fluff were observed. However, the present inventors have found that the discharge from the spinneret can be stabilized by increasing the discharge line speed and the shearing speed, contrary to the general method of reducing the swell of the spinning line due to the ballast effect. In spite of having a phase separation structure, it is possible to stably obtain a fiber having small fineness spots and suppressed generation of dyed spots and fluff. This is because the phase separation structure composed of a hydrophobic polymer (polyethylene terephthalate) -hydrophilic polymer (polyethylene glycol) copolymer is finely dispersed when shearing is applied in the molten state as described above. This is considered to be due to the fact that the phase separation structure appears again after a certain period of time has elapsed after the application of shearing has stopped, although it disappears.

In the present invention, the shear rate when the copolymer of the hydrophobic polymer and the hydrophilic polymer passes through the spinneret is preferably 10000 to 40000 s ⁻¹ . The shear rate when passing through the spinneret is determined by the discharge amount per single hole of the spinneret, the discharge hole diameter, and the melt viscosity of the copolymer of the hydrophobic polymer and the hydrophilic polymer. A shear rate of 10,000 s ^-1 or more when passing through the spinneret is preferable because fibers from the spinneret can be stably discharged, the fineness unevenness is small, and the occurrence of dyed spots and fluff is suppressed. More preferably a shear rate of passing through the spinneret is 12000S ^-1 or more, more preferably 15000S ^-1 or more. On the other hand, if the shear rate when passing through the spinneret is 40000 s ^-1 or less, the spinning stress will not be too high, and the discharge from the spinneret will be stable, so the occurrence of sharkskin, melt fracture, etc. is suppressed, This is preferable because fibers with small fineness spots and suppressed generation of dyed spots and fluff are obtained. More preferably a shear rate of passing through the spinneret is 38000S ^-1 or less, and more preferably 35000S ^-1 or less.

  In the production of the fiber of the present invention, the discharge linear velocity is preferably 10 to 100 m / min. The discharge linear velocity is determined by the discharge amount per single hole of the spinneret, the discharge hole diameter, and the melt viscosity of the copolymer of the hydrophobic polymer and the hydrophilic polymer. A discharge linear velocity of 10 m / min or more is preferable because a fiber from which the discharge from the spinneret is stable, the fineness spots are small, and the occurrence of dyed spots and fluff is suppressed can be obtained. The discharge linear velocity is more preferably 15 m / min or more, and further preferably 20 m / min or more. On the other hand, if the discharge linear velocity is 100 m / min or less, the spinning stress does not become too high, and the discharge from the spinneret is stable, so the occurrence of sharkskin and melt fracture is suppressed, the fineness spots are small, and dyeing is performed. This is preferable because a fiber in which generation of spots and fluff is suppressed can be obtained. The discharge linear velocity is more preferably 90 m / min or less, and further preferably 80 m / min or less.

  In the production of the fiber of the present invention, the spinning draft is preferably 10 to 300. The spinning draft can be calculated by dividing the spinning speed by the discharge linear speed. A spinning draft of 10 or more is preferable because productivity is improved. The spinning draft is more preferably 20 or more, and further preferably 30 or more. On the other hand, if the spinning draft is 300 or less, the spinning stress is not excessively high, the spinning property is good, the fineness unevenness is small, and the fibers in which the occurrence of dyed spots and fluff is suppressed are preferable. The spinning draft is more preferably 250 or less, and even more preferably 200 or less.

  As the spinneret used in the present invention, a known one can be used, and the number of discharge holes can be appropriately selected according to the desired number of filaments. The discharge hole diameter can be appropriately selected according to the shear rate, the discharge linear velocity, and the spinning draft, but is preferably 0.05 to 0.50 mm. If the discharge hole diameter is 0.05 mm or more, the pressure in the spin pack does not become too high, the discharge from the spinneret is stable, the fineness unevenness is small, and the fibers in which the occurrence of dyed spots and fluff is suppressed can be obtained. Therefore, it is preferable. The discharge hole diameter is more preferably 0.10 mm or more, and further preferably 0.15 mm or more. On the other hand, if the discharge hole diameter is 0.50 mm or less, it is preferable because the back surface pressure of the spinneret is not insufficient, and the discharge spots between the discharge holes of the spinneret are suppressed. Further, it is preferable because the spinning draft can be increased without lowering the spinning speed and the productivity is improved. The discharge hole diameter is more preferably 0.40 mm or less, and still more preferably 0.30 mm or less.

  In the present invention, it is preferable to dry the copolymer of the hydrophobic polymer and the hydrophilic polymer so that the water content is 300 ppm or less before performing melt spinning. A water content of 300 ppm or less is preferable because molecular weight reduction due to hydrolysis and foaming due to moisture are suppressed during melt spinning, and spinning can be performed stably. The water content is more preferably 200 ppm or less, and still more preferably 100 ppm or less.

  In the present invention, an antioxidant may be added during melt spinning. As described above, the fiber having a phase separation structure composed of the hydrophobic polymer (polyester) -hydrophilic polymer (polyethylene glycol) copolymer in the present invention is a polyester-polyethylene glycol having a uniform structure having no phase separation structure. Compared with the fiber made of a copolymer, it has high oxidative decomposability, so it is preferable to contain a sufficient amount of an antioxidant in the fiber. Furthermore, by adding it during melt spinning, a polyester-polyethylene glycol copolymer can be added. Compared with the case where it is added at the time of producing the coalescence, it is preferable because scattering of the antioxidant under vacuum and deactivation of the antioxidant due to thermal decomposition can be suppressed. As a method of adding an antioxidant when performing melt spinning, a method in which a polyester-polyethylene glycol copolymer and an antioxidant are dry-blended in advance and then put into a melt spinning machine, a polyester-polyethylene glycol copolymer and an antioxidant are added. Examples include, but are not limited to, a method of feeding the agent from a separate feeder into a melt spinning machine.

  In the present invention, a polyester-polyethylene glycol copolymer chip that has been dried in advance is supplied to a melt spinning machine such as an extruder type or a pressure melter type and melted, and then measured with a metering pump. Then, after introducing into the spinning pack heated in the spinning block and filtering the molten polymer in the spinning pack, it is discharged from the spinneret to form fiber yarns. The fiber yarn discharged from the spinneret is cooled and solidified by a cooling device, taken up by a first godet roller, wound up by a winder through a second godet roller, and taken up as a wound yarn. In addition, in order to improve the spinning maneuverability, productivity, and mechanical properties of the fiber, a heating cylinder or a thermal insulation cylinder having a length of 2 to 20 cm may be installed below the spinneret as necessary. Moreover, you may supply oil to a fiber yarn using an oil supply apparatus, and you may give an entanglement to a fiber yarn using an entanglement apparatus.

  The spinning temperature in melt spinning can be appropriately selected according to the melting point and heat resistance of the copolymer of the hydrophobic polymer and the hydrophilic polymer, but is preferably 240 to 320 ° C. If the spinning temperature is 240 ° C. or higher, the elongation viscosity of the fiber yarn discharged from the spinneret is sufficiently lowered, so that the discharge is stable, and further, the spinning tension is not excessively high and the yarn breakage is suppressed. This is preferable. The spinning temperature is more preferably 250 ° C. or higher, and further preferably 260 ° C. or higher. On the other hand, a spinning temperature of 320 ° C. or lower is preferable because thermal decomposition during spinning can be suppressed, and deterioration of mechanical properties and coloring of fibers can be suppressed. The spinning temperature is more preferably 310 ° C. or lower, and further preferably 300 ° C. or lower.

  The spinning speed in melt spinning can be appropriately selected according to the composition of the copolymer of the hydrophobic polymer and the hydrophilic polymer, the spinning temperature, the spinning draft, and the like. It is preferable that the spinning speed in the two-step method in which the melt spinning is once wound up and then separately stretched is 500 to 5000 m / min. A spinning speed of 500 m / min or more is preferable because the running yarn is stable and yarn breakage can be suppressed. The spinning speed in the two-step method is more preferably 1000 m / min or more, and further preferably 1500 m / min or more. On the other hand, when the spinning speed of the two-step method is 5000 m / min or less, the fiber yarn can be sufficiently cooled, and stable spinning can be performed, which is preferable. The spinning speed in the two-step method is more preferably 4500 m / min or less, and further preferably 4000 m / min or less. Moreover, it is preferable that the spinning speed in the one-step method in which spinning and stretching are performed simultaneously without winding once is 500 to 5000 m / min for the low speed roller and 3000 to 6000 m / min for the high speed roller. It is preferable that the low-speed roller and the high-speed roller are within the above ranges because the running yarn is stabilized, yarn breakage can be suppressed, and stable spinning can be performed. The spinning speed in the one-step method is more preferably 1000 to 4500 m / min for the low speed roller, 3500 to 5500 m / min for the high speed roller, 1500 to 4000 m / min for the low speed roller, and 4000 to 5000 m / min for the high speed roller. More preferably.

  When stretching is performed by a one-step method or a two-step method, any one of a one-step stretching method or a two-step or more multi-stage stretching method may be used. The heating method in stretching is not particularly limited as long as it is a device that can directly or indirectly heat the traveling yarn. Specific examples of the heating method include, but are not limited to, a heating roller, a hot pin, a hot plate, a liquid bath such as hot water and hot water, a hot air (heated air), a gas bath such as steam, and a laser. These heating methods may be used alone or in combination. Heating methods include control of the heating temperature, uniform heating of the running yarn, and contact with the heating roller, contact with the hot pin, contact with the hot plate, and immersion in a liquid bath from the viewpoint of not complicating the device. It can be suitably employed.

  The stretching ratio in the case of stretching can be appropriately selected according to the strength and elongation of the fiber after stretching, but is preferably 1.02 to 7.0 times. A draw ratio of 1.02 or more is preferable because mechanical properties such as fiber strength and elongation can be improved by drawing. The draw ratio is more preferably 1.2 times or more, and further preferably 1.5 times or more. On the other hand, if the draw ratio is 7.0 times or less, yarn breakage during drawing is suppressed, and stable drawing can be performed. The draw ratio is more preferably 6.0 times or less, and still more preferably 5.0 times or less.

  The stretching temperature in the case of stretching can be appropriately selected according to the strength and elongation of the fiber after stretching, but is preferably 60 to 150 ° C. A drawing temperature of 60 ° C. or higher is preferable because the yarn supplied to the drawing is sufficiently preheated, the thermal deformation during drawing becomes uniform, and the occurrence of fineness spots can be suppressed. The stretching temperature is more preferably 65 ° C. or higher, and further preferably 70 ° C. or higher. On the other hand, a stretching temperature of 150 ° C. or lower is preferable because thermal decomposition of the fiber can be suppressed. Moreover, since the slipperiness of the fiber with respect to a drawing roller becomes favorable, yarn breakage is suppressed and stable drawing can be performed, which is preferable. The stretching temperature is more preferably 145 ° C. or less, and further preferably 140 ° C. or less. Moreover, you may perform the heat setting of 60-150 degreeC as needed.

  The stretching speed for stretching can be appropriately selected depending on whether the stretching method is a one-step method or a two-step method. In the case of the one-step method, the speed of the high-speed roller corresponding to the spinning speed corresponds to the stretching speed. The stretching speed when stretching by the two-step method is preferably 30 to 1000 m / min. A stretching speed of 30 m / min or more is preferable because the running yarn is stable and yarn breakage can be suppressed. In the case of stretching by a two-step method, the stretching speed is more preferably 50 m / min or more, and further preferably 100 m / min or more. On the other hand, a stretching speed of 1000 m / min or less is preferable because yarn breakage during stretching can be suppressed and stable stretching can be performed. The stretching speed when stretching by the two-step method is more preferably 800 m / min or less, and further preferably 500 m / min or less.

  In this invention, you may dye | stain in any state of a fiber or a fiber structure as needed. In the present invention, a disperse dye can be suitably employed as the dye.

  There is no restriction | limiting in particular in the dyeing | staining method in this invention, A cheese dyeing machine, a liquid dyeing machine, a drum dyeing machine, a beam dyeing machine, a jigger, a high-pressure jigger etc. can be employ | adopted suitably according to a well-known method.

  In this invention, there is no restriction | limiting in particular regarding dye density | concentration and dyeing | staining temperature, A well-known method can be employ | adopted suitably. If necessary, scouring may be performed before the dyeing process, or reduction cleaning may be performed after the dyeing process.

  The fiber of the present invention and the fiber structure comprising the same have suppressed dyeing spots and fluff generation, are excellent in hygroscopicity and antistatic properties in a low-temperature and low-humidity environment, and dissolves hydrophilic compounds during dyeing and use Is suppressed. Therefore, it can be suitably used in applications where quality and comfort are required. Examples include, but are not limited to, general clothing uses, sports clothing uses, bedding uses, interior uses, and material uses.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example is calculated | required with the following method.

A. In an environment with a fineness of 20 ° C. and a humidity of 65% RH, 100 m of the fiber obtained in the example was scraped using an electric measuring machine manufactured by INTEC. The weight of the obtained skein was measured, and the fineness (dtex) was calculated using the following formula. In addition, the measurement was performed 5 times per sample, and the average value was defined as the fineness.
Fineness (dtex) = weight of fiber 100 m (g) × 100

B. Strength and elongation The strength and elongation were calculated according to JIS L1013: 1999 (chemical fiber filament yarn test method) 8.5 using the fiber obtained in the example as a sample. In an environment of a temperature of 20 ° C. and a humidity of 65% RH, a tensile test was performed using an autograph AG-50NISMS type manufactured by Shimadzu Corporation under the conditions of an initial sample length of 20 cm and a tensile speed of 20 cm / min. The strength (cN / dtex) is calculated by dividing the stress (cN) at the point indicating the maximum load by the fineness (dtex), and using the elongation (L1) and the initial sample length (L0) at the point indicating the maximum load, The elongation (%) was calculated by the formula. The measurement was carried out 10 times per sample, and the average values were taken as the strength and elongation.
Elongation (%) = {(L1-L0) / L0} × 100

C. Toughness The toughness of the fiber was calculated by the following formula using the strength (cN / dtex) and elongation (%) calculated in B above.
Toughness = Strength x (Elongation) ^1/2

D. Initial tensile resistance The initial tensile resistance was calculated according to JIS L1013: 1999 (chemical fiber filament yarn test method) 8.10. A tensile test is performed in the same manner as in B above to draw a load-elongation curve, and the maximum point of load change with respect to elongation change is obtained near the origin of this curve, and JIS L1013: 1999 (chemical fiber filament yarn test method) 8.10. The initial tensile resistance (cN / dtex) was calculated using the formula described. The measurement was performed 5 times per sample, and the average value was defined as the initial tensile resistance.

E. Boiling water shrinkage Under a temperature of 20 ° C. and a humidity of 65% RH, a skein (10 turns) made of the fiber obtained by the example was prepared using a 1 m / circular measuring machine and allowed to stand for 24 hours. I put it. Thereafter, in this environment, a sample length L0 was measured by applying a load of 0.09 cN / dtex to the skein. Next, the skein was treated in boiling water at 98 ° C. with no load for 15 minutes and then air-dried for 24 hours. A load of 0.09 cN / dtex was applied to the skein to measure the sample length L1. The boiling water shrinkage (%) was calculated by the following formula using the sample lengths L0 and L1 before and after the treatment in boiling water. In addition, the measurement was performed 3 times per sample, and the average value was defined as the boiling water shrinkage.
Boiling water shrinkage (%) = {(L0−L1) / L0)} × 100

F. Maximum diameter of dispersed phase in fiber cross section After embedding the fiber obtained in the example with an epoxy resin, the fiber is cut in a direction perpendicular to the fiber axis for each epoxy resin using an LKB ultramicrotome LKB-2088. Thus, an ultrathin section having a thickness of about 100 nm was obtained. The obtained ultrathin sections were stained in the ruthenium tetroxide gas phase at room temperature for about 4 hours, and then the stained surfaces were cut with an ultramicrotome to produce ultrathin sections stained with ruthenium tetroxide. did. Using a transmission electron microscope (TEM) H-7100FA manufactured by Hitachi, the cross section perpendicular to the fiber axis, that is, the cross section of the fiber was observed on the stained ultrathin section under the condition of an acceleration voltage of 100 kV. A micrograph of the surface was taken. Observation was performed at each magnification of 2000 times, 8000 times, 20000 times, and 40000 times, and when taking a micrograph, the highest magnification at which 300 or more dispersed phases could be observed was selected. Using the image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.) for the photographed images, the diameters of 300 randomly dispersed phases were measured, and the maximum value was the maximum diameter (nm) of the dispersed phase in the fiber cross section. ). Since the disperse phase present in the fiber cross section is not necessarily a perfect circle, when it was not a perfect circle, the area was measured and the diameter when converted to a perfect circle was adopted as the diameter of the disperse phase.

G. Maximum diameter of dispersed phase in fiber longitudinal section After embedding the fiber obtained in the example with an epoxy resin, the fiber is placed in a direction parallel to the fiber axis together with the epoxy resin using an LKB ultramicrotome LKB-2088. Cutting was performed to obtain an ultrathin section having a thickness of about 100 nm. The obtained ultrathin sections were stained in the ruthenium tetroxide gas phase at room temperature for about 4 hours, and then the stained surfaces were cut with an ultramicrotome to produce ultrathin sections stained with ruthenium tetroxide. did. Using a transmission electron microscope (TEM) H-7100FA manufactured by Hitachi, the cross section parallel to the fiber axis, that is, the longitudinal section of the fiber, was observed with respect to the stained ultrathin section. A micrograph of the surface was taken. Observation was performed at respective magnifications of 2000 times, 8000 times, 20000 times, and 40000 times, and when taking a micrograph, the highest magnification at which 300 or more streaky dispersed phases could be observed was selected. Using the image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.), the diameter of 300 randomly dispersed phases was measured and the maximum value was taken as the maximum diameter (nm) of the dispersed phase in the fiber longitudinal section. ). In addition, the diameter of the dispersed phase in the fiber longitudinal section was measured with respect to the direction perpendicular to the fiber axis.

H. Fineness fluctuation value U% (hi)
The fineness variation value U% (hi) is obtained by using the fiber obtained in the example as a sample and using a Worcester tester 4-CX manufactured by Zerbegger Wooster, measuring speed 200 m / min, measuring time 2.5 minutes, measured fiber length U% (half inert) was measured under conditions of 500 m and a twist number of 12000 / m (S twist). The measurement was performed five times for each sample, and the average value was defined as the fineness variation value U% (hi).

I. Single yarn diameter CV%
After vapor-depositing the fibers obtained in Examples with a platinum-palladium alloy, the cross section perpendicular to the fiber axis, that is, the cross section of the fiber was observed using a Hitachi scanning electron microscope (SEM) S-4000 type. A micrograph of the fiber cross section was taken. The observation is performed at each magnification of 100 times, 300 times, 500 times, 1000 times, 3000 times, 5000 times, and 10,000 times, and when taking a micrograph, the highest magnification at which all the single yarns in the sample can be observed is observed. Selected. About the photographed photograph, the single yarn diameter was measured using image analysis software (WinROOF manufactured by Mitani Corporation). When the number of single yarns in the sample is 50 or more, the single yarn diameter of 50 single yarns randomly selected is measured. When the number of single yarns in the sample is less than 50, a plurality of yarns manufactured under the same conditions are measured. The single yarn diameter of a total of 50 single yarns was measured using the above samples. Since the fiber cross section is not necessarily a perfect circle, the area was measured when it was not a perfect circle, and the diameter when converted to a perfect circle was adopted as the single yarn diameter. After calculating the average value (X) of the single yarn diameter and the standard deviation (σ) of the single yarn diameter, the single yarn diameter CV% was calculated by the following formula.
Single yarn diameter CV% = (σ / X) × 100

J. et al. Single yarn fineness CV%
The single yarn fineness was determined by using the fiber obtained in the example as a sample and breaking it into single yarns, then using a motorcycle bro fineness measuring instrument DC-11 manufactured by Search Corp., measuring sample length 25 mm, fineness of the measurement sample (denier conversion) Value) x 0.4 g of load was applied, and vibration was applied at a frequency of 1880 Hz. When the number of single yarns in the sample is 20 or more, the single yarn fineness of 20 randomly extracted single yarns is measured. When the number of single yarns in the sample is less than 20, a plurality of yarns manufactured under the same conditions are measured. The single yarn fineness of a total of 20 single yarns was measured using these samples. After calculating the average value (X) of the single yarn fineness and the standard deviation (σ) of the single yarn fineness, the single yarn fineness CV% was calculated by the following formula.
Single yarn fineness CV% = (σ / X) × 100

K. Single yarn strength CV%, single yarn elongation CV%
The single yarn strength and single yarn elongation were calculated according to JIS L1013: 1999 (chemical fiber filament yarn test method) 8.5 after disassembling the fibers obtained in the examples into single yarns. Under an environment of a temperature of 20 ° C. and a humidity of 65% RH, a tensile test was performed using an autograph AG-50NISMS type manufactured by Shimadzu Corporation under conditions of an initial sample length of 5 cm and a tensile speed of 20 cm / min. The single yarn elongation (%) was calculated by the following equation using the stress (cN) at the point indicating the maximum load as the single yarn strength and using the elongation (L1) at the point indicating the maximum load and the initial sample length (L0). When the number of single yarns in the sample is 50 or more, the single yarn strength and the single yarn elongation of 50 randomly extracted yarns are measured. When the number of single yarns in the sample is less than 50, the same applies. Using a plurality of samples manufactured under the conditions, the single yarn strength and single yarn elongation of a total of 50 single yarns were measured. After calculating the average value (X) and the standard deviation (σ) for each single yarn strength and single yarn elongation, single yarn strength CV% and single yarn elongation CV% were calculated according to the following formulas.
Elongation (%) = {(L1-L0) / L0} × 100
Single yarn strength CV% = (σ / X) × 100
Single yarn elongation CV% = (σ / X) × 100

L. Content of unreacted PEG (polyethylene glycol) 500 mg of the fiber obtained in the example was weighed into a screw tube, added with 2 mL of hexafluoroisopropanol, and allowed to stand for 24 hours in an environment of temperature 20 ° C. and humidity 65% RH. And dissolved. Add 2 mL of chloroform to the screw tube, transfer the mixture to a 100 mL volumetric flask, add 6 mL of chloroform to the residue in the screw tube, transfer to the above volumetric flask, add acetonitrile to the volumetric flask, and make a constant volume to 100 mL. did. The component which precipitated by adding acetonitrile was removed by filtration, the filtrate was concentrated to dryness using an evaporator, and the volume was adjusted with 5 mL of acetonitrile. 1 mL of the solution after the fixed volume was transferred to a 10 mL volumetric flask, adjusted to 10 mL with acetonitrile, and then filtered with a 0.45 μm PTFE filter, and the obtained filtrate was used as a sample for HPLC measurement. Using this sample, HPLC measurement was performed with an HPLC apparatus (LC-20A manufactured by Shimadzu Corporation) under the following conditions, and it was included in the sample for HPLC measurement from a calibration curve of a standard substance (PEG) prepared in advance. PEG was quantified, and the unreacted PEG content (wt%) contained in the fiber obtained by the example was calculated. The measurement was performed 5 times per sample, and the average value was defined as the unreacted PEG content.
Column: GL Science Inertsil ODS-3 (inner diameter 3 mm, length 150 mm, particle diameter 5 μm)
Detector: ELSD manufactured by Shimadzu Corporation
Moving bed: Water (solvent A), acetonitrile (solvent B)
Time program: 0 → 15 minutes (solvent A: solvent B = 60: 40 → 0: 100), 15 → 25 minutes (solvent A: solvent B = 0: 100)
Flow rate: 0.8 mL / min Injection volume: 10 μL
Column temperature: 45 ° C
Standard substance: PEG

M.M. Antioxidant Content To 500 mg of the fiber obtained in the Example, 25 mL of a 1 mol / L sodium methoxide-methanol solution and 25 mL of methyl acetate were added and refluxed for 1 hour, followed by neutralization by adding 2 mL of acetic acid. The mixture after neutralization was concentrated to dryness using a rotary evaporator, 50 mL of water was added, and the mixture was extracted with 20 mL of chloroform and separated into a chloroform layer and an aqueous layer. Using a rotary evaporator, the chloroform layer was concentrated to dryness, and 2.5 mL of chloroform was added to prepare a sample for chromatographic measurement. Using this sample, GC measurement or HPLC measurement was performed, and the antioxidant contained in the chromatographic measurement sample was quantified from the calibration curve of the standard substance (antioxidant used in the example). The antioxidant content (wt%) contained in the obtained fiber was calculated. In addition, the measurement was performed 5 times per sample and the average value was made into antioxidant content.

N. Time until rising half-value point The fiber obtained in the example was used as a sample, 10 mg of the sample was put in an aluminum container, and in a mixed gas atmosphere of nitrogen: oxygen = 80 vol%: 20 vol% in a TG-DTA manufactured by Seiko Instruments Inc. The mixture was heated from room temperature to 160 ° C. at a mixed gas flow rate of 200 mL / min and a heating rate of 30 ° C./min, and then held at 160 ° C. for 360 minutes. Thereafter, differential thermogravimetric analysis (DTG) is performed using analysis software (Muse, manufactured by Seiko Instruments Inc.), the time to reach 160 ° C. is defined as 0 minute, and the time (min) until the rising half-value point of the DTG peak is obtained. Calculated. If the rising half-value point of the DTG peak appears before reaching 160 ° C, the time to the rising half-value point is set to a negative value. If no DTG peak is observed while holding at 160 ° C for 360 minutes, The time to half point was set to 360 minutes or more. The measurement was performed five times for each sample, and the average value was defined as the time to the rising half-value point.

O. Frictional band voltage After using the fiber obtained by the example as a sample, about 2 g of cylindrical knitting was produced using a Yoko Sangyo circular knitting machine NCR-BL (3-inch and half (8.9 cm), 27 gauge). After scouring for 20 minutes at 80 ° C. in an aqueous solution containing 1 g / L of sodium carbonate and a surfactant Sunmol BK-80 manufactured by Nikka Chemical, it was dried in a hot air dryer at 60 ° C. for 60 minutes.

  The frictional voltage (V) is calculated according to JIS L1094: 1997 (chargeability test method for woven fabrics and knitted fabrics) 5.2 under the atmosphere of a temperature of 10 ° C. and a humidity of 10% RH using a scoured tubular knitting as a sample. did. In addition, the measurement was performed 5 times per sample, and the average value was defined as the frictional voltage.

P. Moisture absorption difference (△ MR)
The moisture absorption rate (%) was calculated according to the moisture content of JIS L1096: 2010 (woven fabric and knitted fabric test method) 8.10 using a scoured tubular knitting produced in the same manner as O above as a sample. First, the tube knitting was vacuum-dried at 110 ° C. for 24 hours, and the weight (W0) of the tube knitting when completely dried was measured. Next, the cylinder knitting is left in the constant temperature and humidity chamber LHU-123 manufactured by ESPEC adjusted to a temperature of 20 ° C. and a humidity of 65% RH for 24 hours. After measuring the weight (W1) of the cylinder knitting, the temperature is 30 ° C. The cylinder knitting was left for 24 hours in a thermo-hygrostat adjusted to a humidity of 90% RH, and the weight (W2) of the cylinder knitting was measured. The moisture absorption rate MR1 (%) after standing for 24 hours in an atmosphere of temperature 20 ° C. and humidity 65% RH is calculated based on the weights W0 and W2 of the tube knitting, and is completely dried based on the weights W0 and W2 of the tube knitting. From the state, the moisture absorption rate MR2 (%) when left in a 30 ° C., 90% RH atmosphere for 24 hours was calculated, and the moisture absorption difference (ΔMR) was calculated by the following equation. The measurement was performed five times for each sample, and the average value was defined as the difference in moisture absorption rate (ΔMR).
Moisture absorption difference (ΔMR) (%) = MR2−MR1

Q. Weight reduction rate after hydrothermal treatment Using the fiber obtained by the example as a sample, cylinder knitting about 2 g using a circular knitting machine NCR-BL (bottle diameter 3 inch half (8.9 cm), 27 gauge) manufactured by Eiko Sangyo Co., Ltd. After that, the tubular knitting was immersed in ethanol at a bath ratio of 1:50, a treatment temperature of 25 ° C., and a treatment time of 1 minute. The immersion in ethanol was repeated 3 times in total to remove the oil agent adhering to the tube knitting, and after drying for 60 minutes in a hot air dryer at 60 ° C., the weight (W0) of the tube knitting was measured. In addition, fresh ethanol was used for every immersion. Subsequently, hot water treatment was performed under conditions of a bath ratio of 1: 100, a treatment temperature of 100 ° C., and a treatment time of 60 minutes. The tubular knitting after the hot water treatment was dried for 60 minutes in a hot air dryer at 60 ° C., and then the weight (W1) of the tubular knitting was measured. The weight reduction rate (%) after the hot water treatment was calculated by the following formula using the weights W0 and W1 of the tube knitting. The measurement was performed three times for each sample, and the average value was defined as the weight reduction rate.
Weight reduction rate (%) = {(W0−W1) / W0)} × 100

R. Leveling property After scouring the cylindrical knitting produced in the same manner as O above, heat-heat set at 160 ° C. for 2 minutes, and as a disperse dye, Kayalon Polyester Black EX-SF200 manufactured by Nippon Kayaku as a disperse dye. Was dyed in a dyeing solution adjusted to pH 5.0 with a bath ratio of 1: 100, a dyeing temperature of 130 ° C., and a dyeing time of 60 minutes. In Examples 38 to 47, 4% by weight of Catholy Blue FB-DP manufactured by Hodogaya Chemical Co., Ltd. was added as a cationic dye, and the bath ratio was 1: 100, and the dyeing temperature was 130 ° C. in a dyeing solution adjusted to pH 4.0. The dyeing was performed under the condition of a dyeing time of 60 minutes. Regarding tube knitting after dyeing, according to the consensus of five inspectors who have experience of quality judgment for more than 5 years, “It is dyed very uniformly and no dyed spots are observed” `` Stained and almost no dyed spots are found '' ○, `` Almost not evenly dyed and slightly dyed spots are seen '' △, `` Uniformly dyed and spotted spots are not clearly seen '' Was determined to be “x”, and ○ and ◎ were determined to be acceptable.

S. Quality Regarding the tube knitting after dyeing with the above R, according to the consensus of 5 inspectors with experience of quality judgment for more than 5 years, “No fluff and excellent quality” ◎, “No fluff and quality “Excellent” was determined as “Good”, “Fuzzy and inferior in quality” was evaluated as “△”, and “Many fluff and inferior in quality” were evaluated as “x”, and “Good” and “Excellent” were determined as acceptable.

Example 1
About 100 kg of bis (β-hydroxyethyl) terephthalate was charged into the esterification reaction tank and maintained at a temperature of 250 ° C., then 89.2 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 39.8 kg of ethylene glycol (manufactured by Nippon Shokubai) Were sequentially fed over 2.5 hours. After completion of the supply, the esterification reaction was carried out for 2 hours to obtain an esterification reaction product. Subsequently, 13.6 kg of ethylene glycol (manufactured by Nippon Shokubai), 16.8 kg of polyethylene glycol having a number average molecular weight of 8300 melted by heating to 70 ° C. (PEG6000S manufactured by Sanyo Chemical Industries) were sequentially added to the polycondensation tank, and then esterified. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 250 ° C. through a transfer pipe connecting the conversion reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 250 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 30 g of antimony trioxide as a polymerization catalyst, manganese acetate 22 g was added and stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 250 ° C. to 285 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 25 Pa, and then the polymerization reaction was performed for 3 hours. The polymerization reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. It was confirmed by ¹ H-NMR that the copolymerization ratio of polyethylene glycol in the obtained polymerization reaction product was 14% by weight.

  The obtained pellets were vacuum-dried at 150 ° C. for 12 hours (water content after drying: 95 ppm), then supplied to an extruder-type spinning machine to melt, and a spinneret (discharge) at a spinning temperature of 290 ° C. and a discharge rate of 57 g / min. A spun yarn was obtained by discharging from a hole diameter of 0.23 mm, a discharge hole length of 0.60 mm, a discharge hole number of 36, and a round hole. The spun yarn is cooled by cooling air with an air temperature of 20 ° C. and an air speed of 20 m / min, applied with an oil agent by a lubricating device, converged, and taken up by a first godet roller rotating at 3000 m / min. An undrawn yarn of 190 dtex-36f was obtained by winding with a winder via a second godet roller rotating at the same speed as the dead roller. The obtained undrawn yarn was drawn under conditions of a first hot roller temperature of 90 ° C., a second hot roller temperature of 130 ° C. and a draw ratio of 1.9 times to obtain a drawn yarn of 100 dtex-36f.

  Table 1 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The obtained fiber had good fiber properties such as strength and toughness. The fibers had a phase separation structure, and the maximum diameter of the dispersed phase in the fiber cross section was 30 nm, and the maximum diameter of the dispersed phase in the fiber longitudinal section was 31 nm, and they were very finely dispersed. Further, while having a phase separation structure, U% (hi) was 1.0%, which was a very homogeneous fiber. Regarding the fabric properties, the antistatic property and the hygroscopic property were extremely excellent. Moreover, the weight reduction rate after the hot water treatment was low, elution of the hydrophilic compound was suppressed, and the leveling and quality were acceptable levels.

Examples 2-4
A drawn yarn was produced in the same manner as in Example 1 except that the copolymerization ratio, discharge amount, and spinneret (discharge hole diameter, discharge hole length, discharge hole number) of the hydrophilic polymer were changed as shown in Table 1.

  Table 1 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. As the copolymerization ratio of the hydrophilic polymer decreases, the fiber properties such as strength and toughness improve, the maximum diameter of the dispersed phase in the fiber cross section and fiber cross section decreases, and U% (hi) improves. It was. On the other hand, the antistatic property and hygroscopicity were improved as the copolymerization rate of the hydrophilic polymer increased.

Examples 5-7
A drawn yarn was produced in the same manner as in Example 4 except that the discharge hole diameter of the spinneret was changed as shown in Table 1.

  Table 1 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. As the discharge hole diameter decreases and the shear rate when passing through the spinneret increases, the fiber properties such as strength and toughness improve, and the maximum diameter of the dispersed phase in the fiber cross section and fiber longitudinal section decreases, and U% (hi ) Was good.

Examples 8 and 9
A drawn yarn was produced in the same manner as in Example 7 except that the copolymerization ratio of the hydrophilic polymer was changed as shown in Table 2.

  Table 2 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the copolymerization rate of the hydrophilic polymer was changed, U% (hi) was low, and a homogeneous fiber was obtained.

Examples 10 and 11
A drawn yarn was produced in the same manner as in Example 4 except that the number average molecular weight of the hydrophilic polymer and the spinneret (discharge hole diameter) were changed as shown in Table 2. As the hydrophilic polymer, polyethylene glycol having a number average molecular weight of 11000 (PEG 10000 manufactured by Sanyo Chemical Industries) was used in Example 10, and polyethylene glycol having a number average molecular weight of 20000 (PEG 20000 manufactured by Sanyo Chemical Industries) was used in Example 11.

  Table 2 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the number average molecular weight of the hydrophilic polymer was changed, the fiber characteristics such as strength and toughness were good, U% (hi) was low, and uniform fibers were obtained.

Examples 12 and 13
A drawn yarn was produced in the same manner as in Example 1 except that the spinning speed was changed as shown in Table 2 and the draw ratio was changed to 5.7 times in Example 12 and 2.85 times in Example 13.

  Table 2 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the spinning speed was changed, fiber properties such as strength and toughness were good, U% (hi) was low, and uniform fibers were obtained.

Example 14
Citrate chelate titanium complex equivalent to 10 ppm in terms of titanium atom, 82.5 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals), and 49.1 kg of 1,3-propanediol are obtained at a temperature of 240 ° C. In the esterification reaction tank maintained at a pressure of 1.2 × 10 ⁵ Pa, the esterification reaction was performed until the temperature of the distillate fell below 90 ° C. to obtain an esterification reaction product. Subsequently, 16.7 kg of 1,3-propanediol, 16.8 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Chemical Industries) melted by heating to 70 ° C. were sequentially added to the polycondensation tank, followed by esterification. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 240 ° C. through a transfer pipe connecting the reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 240 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 11 g of magnesium acetate tetrahydrate as a polymerization catalyst And stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 240 ° C. to 280 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 40 Pa, and then the polymerization reaction was performed for 3 hours. The polymerization reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. It was confirmed by ¹ H-NMR that the copolymerization ratio of polyethylene glycol in the obtained polymerization reaction product was 14% by weight.

  The obtained pellets were vacuum-dried at 150 ° C. for 12 hours, then supplied to an extruder-type spinning machine and melted, and a spinneret (discharge hole diameter 0.23 mm, discharge hole length at a spinning temperature of 265 ° C. and a discharge rate of 57 g / min. 0.60 mm, 36 discharge holes, round holes) to obtain a spun yarn. The spun yarn is cooled by cooling air with an air temperature of 20 ° C. and an air speed of 20 m / min, applied with an oil agent by a lubricating device, converged, and taken up by a first godet roller rotating at 3000 m / min. An undrawn yarn of 190 dtex-36f was obtained by winding with a winder via a second godet roller rotating at the same speed as the dead roller. The obtained undrawn yarn was drawn under conditions of a first hot roller temperature of 55 ° C., a second hot roller temperature of 130 ° C., and a draw ratio of 1.9 times to obtain a drawn yarn of 100 dtex-36f.

  Table 2 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the hydrophobic polymer was changed to polypropylene terephthalate, the fiber properties such as strength and toughness were good, U% (hi) was low, and uniform fibers were obtained.

Example 15
Citrate chelate titanium complex equivalent to 10 ppm in terms of titanium atom, 82.5 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals), and 89.5 kg of 1,4-butanediol are obtained at a temperature of 220 ° C. In the esterification reaction tank maintained at a pressure of 1.2 × 10 ⁵ Pa, the esterification reaction was performed until the temperature of the distillate fell below 90 ° C. to obtain an esterification reaction product. Subsequently, 19.7 kg of 1,4-butanediol, 16.8 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Chemical Industries) heated to 70 ° C. and melted were sequentially added to the polycondensation tank, and then esterified. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 220 ° C. through a transfer pipe connecting the reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 220 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 11 g of magnesium acetate tetrahydrate as a polymerization catalyst And stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 220 ° C. to 250 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 60 Pa, and then the polymerization reaction was performed for 3 hours. The polymerization reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Copolymerization ratio of polyethylene glycol in the resulting polymerization reaction product was confirmed by ¹ H-NMR to be a 14% by weight.

  The obtained pellets were vacuum-dried at 150 ° C. for 12 hours, then supplied to an extruder-type spinning machine, melted, and spinneret (discharge hole diameter 0.23 mm, discharge hole length at a spinning temperature of 260 ° C. and a discharge rate of 57 g / min. 0.60 mm, 36 discharge holes, round holes) to obtain a spun yarn. The spun yarn is cooled by cooling air with an air temperature of 20 ° C. and an air speed of 20 m / min, applied with an oil agent by a lubricating device, converged, and taken up by a first godet roller rotating at 3000 m / min. An undrawn yarn of 190 dtex-36f was obtained by winding with a winder via a second godet roller rotating at the same speed as the dead roller. The obtained undrawn yarn was drawn under conditions of a first hot roller temperature of 65 ° C., a second hot roller temperature of 130 ° C. and a draw ratio of 1.9 times to obtain a drawn yarn of 100 dtex-36f.

  Table 2 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the hydrophobic polymer was changed to polybutylene terephthalate, fiber properties such as strength and toughness were good, U% (hi) was low, and homogeneous fibers were obtained.

Comparative Example 1
Using polyethylene terephthalate (intrinsic viscosity IV = 0.66), spinning and stretching were carried out in the same manner as in Example 1.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Fiber characteristics such as strength and toughness were good, U% (hi) was low, and homogeneous fibers were obtained. However, since it is a fiber composed only of a hydrophobic polymer, it did not have a phase separation structure. Regarding the fabric characteristics, although the leveling property and quality were extremely excellent, the frictional voltage was 9800 V, the antistatic property was extremely low, ΔMR was 0.1%, and the hygroscopicity was extremely low.

Comparative Examples 2-4
A drawn yarn was produced in the same manner as in Example 4 except that the number average molecular weight of the hydrophilic polymer was changed as shown in Table 3. As the hydrophilic polymer, polyethylene glycol having a number average molecular weight of 3400 (PEG 4000 manufactured by Sanyo Chemical Industries) was used in Comparative Example 2, polyethylene glycol having a number average molecular weight of 6000 (PEG 6000 manufactured by Aldrich) in Comparative Example 3, and number average in Comparative Example 4. Polyethylene glycol having a molecular weight of 100,000 (R-150 manufactured by Meisei Chemical Industry) was used.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. In Comparative Example 2, fiber properties such as strength and toughness were good, U% (hi) was low, and homogeneous fibers were obtained. However, since the number average molecular weight of polyethylene glycol was less than 7000, it did not have a phase separation structure. Regarding the fabric characteristics, although the leveling property and the quality were extremely excellent, the frictional voltage was 7600 V, which was inferior in the antistatic property. In Comparative Example 3, as in Comparative Example 2, fiber properties such as strength and toughness were good, U% (hi) was low, and homogeneous fibers were obtained, but the number average molecular weight of polyethylene glycol was 7000. Therefore, it did not have a phase separation structure. The fabric characteristics were excellent in leveling and quality, but the frictional voltage was 6900 V, which was inferior in antistatic performance. In Comparative Example 4, since the number average molecular weight of polyethylene glycol was high, the maximum diameter of the dispersed phase in the fiber cross section and fiber longitudinal section was large, and a coarse phase separation structure was formed. Therefore, in addition to low fiber properties such as strength and toughness, U% (hi) is high and the fiber is extremely heterogeneous and cannot be used. As for the fabric properties, the leveling and quality were extremely inferior.

Comparative Example 5
A drawn yarn was produced in the same manner as in Example 8 except that the copolymerization ratio of the hydrophilic polymer was changed as shown in Table 3.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Due to the high copolymerization rate of the hydrophilic polymer, the discharge from the spinneret becomes unstable. As a result, the fiber properties such as strength and toughness are extremely low, and U% (hi) is high and extremely heterogeneous. The fiber was unbearable for use. As for the fabric properties, the leveling and quality were extremely inferior.

Comparative Examples 6 and 7
The copolymerization rate, discharge amount, and spinneret (discharge hole diameter, discharge hole length, discharge hole number) of the hydrophilic polymer were changed as shown in Table 3, and the draw ratio was 3.3 times for both Comparative Examples 6 and 7. Except for the above, a drawn yarn was produced in the same manner as in Example 12.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. In Comparative Example 6, since the shear rate at the time of passing through the spinneret is low, the discharge from the spinneret becomes extremely unstable. As a result, the fiber characteristics such as strength and toughness are extremely low, and U% (hi) is High and very heterogeneous fibers, which could not be used. As for the fabric properties, the leveling and quality were extremely inferior. In Comparative Example 7, since the shear rate when passing through the spinneret is high, the spinning stress becomes high and the discharge from the spinneret becomes unstable. As a result, U% (hi) is slightly high and the fiber lacks homogeneity. there were. As for the fabric properties, the leveling quality and quality did not reach acceptable levels.

Comparative Example 8
In Example 4, after the transfer of BHT, polyethylene glycol was charged from above into a polycondensation tank in a powder state without being heated and melted. Furthermore, immediately after the addition of polyethylene glycol, stirring was not performed at 250 ° C. for 1 hour. A stretched yarn was prepared in the same manner as in Example 4 except that the polymerization was started.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Polyethylene glycol was added in a powder state, and further, no stirring was performed after the addition of polyethylene glycol, and polymerization was started with insufficient dispersion of polyethylene glycol in the esterification reaction product. As a result of the formation of such a phase separation structure, even when fiberized by melt spinning, the maximum diameter of the dispersed phase in the fiber cross section and fiber longitudinal section was large, and a coarse phase separation structure was formed. Therefore, the fiber characteristics such as strength and toughness are low, U% (hi) is high, and the fiber lacks homogeneity. As for the fabric properties, the leveling quality and quality did not reach acceptable levels.

Comparative Example 9
About 100 kg of bis (β-hydroxyethyl) terephthalate was charged into the esterification reaction tank and maintained at a temperature of 250 ° C., then 89.2 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 39.8 kg of ethylene glycol (manufactured by Nippon Shokubai) Were sequentially fed over 2.5 hours. After completion of the supply, the esterification reaction was carried out for 2 hours to obtain an esterification reaction product. After transferring 110.6 kg of the obtained esterification reaction product to a polycondensation tank heated to 250 ° C. through a transfer pipe connecting the esterification reaction vessel and the polycondensation vessel, the mixture was stirred at 250 ° C. for 1 hour, 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an antifoaming agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a thermal stabilizer and stirring for 10 minutes, 30 g of antimony trioxide as a polymerization catalyst, Manganese acetate 22g was added and stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was increased from 250 ° C. to 285 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 25 Pa, and then the polymerization reaction was performed for 2 hours 30 minutes. . Thereafter, the inside of the polycondensation tank was purged with nitrogen to return to normal pressure, and as a powdered number average molecular weight 8300 polyethylene glycol (PEG6000S manufactured by Sanyo Chemical Industries), as an antioxidant (added after the start of the polycondensation reaction) 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) is added to the polycondensation tank, and the pressure in the polycondensation tank is changed to atmospheric pressure. The pressure was reduced from 25 to 25 Pa, and then the polymerization reaction was performed for 30 minutes. The polymerization reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Using the obtained pellets, a drawn yarn was produced in the same manner as in Example 4.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. When polyethylene glycol is added in a powder state, and the polymerization reaction time after addition of polyethylene glycol is short, a coarse phase separation structure is formed in the polymerization reaction product, resulting in fiber formation by melt spinning. However, the maximum diameter of the dispersed phase in the fiber cross section and fiber longitudinal section was large, and a coarse phase separation structure was formed. Therefore, U% (hi) was high and the fiber lacked homogeneity. Moreover, since the polymerization reaction time after adding polyethylene glycol was short, both the unreacted PEG content and the weight reduction rate after the hot water treatment were both high, and the leveling quality and quality did not reach acceptable levels.

Comparative Example 10
88 kg of polyethylene terephthalate (IV = 0.66), 12 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Chemical Industries), pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4) as an antioxidant -Hydroxyphenol) propionate) (BASF, Irganox 1010) 150 g was melt kneaded at 285 ° C. using a biaxial extruder, cut to about 5 mm to produce pellets, and drawn yarns were prepared in the same manner as in Example 4. .

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. When polyethylene terephthalate and polyethylene glycol were melt-kneaded, the maximum diameter of the dispersed phase in the fiber cross-section and fiber cross-section was large, U% (hi) was high, and the fiber lacked homogeneity. In addition, both the unreacted PEG content and the weight loss after hot water treatment were high, and the leveling quality and quality did not reach acceptable levels.

Comparative Example 11
In Comparative Example 2, a drawn yarn was produced in the same manner as in Comparative Example 2, except that the amount of the antioxidant (added before the start of the polycondensation reaction) was changed to 600 g.

  Table 3 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Fiber characteristics such as strength and toughness were good, U% (hi) was low, and homogeneous fibers were obtained. However, since the number average molecular weight of polyethylene glycol was less than 7000, it did not have a phase separation structure. As for the fabric characteristics, although the leveling property and the quality were extremely excellent, the frictional voltage was 7200 V, which was inferior in antistatic performance.

Example 16
About 100 kg of bis (β-hydroxyethyl) terephthalate was charged into the esterification reaction tank and maintained at a temperature of 250 ° C., then 89.2 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals) and 39.8 kg of ethylene glycol (manufactured by Nippon Shokubai) Were sequentially fed over 2.5 hours. After completion of the supply, the esterification reaction was carried out for 2 hours to obtain an esterification reaction product. Subsequently, 13.6 kg of ethylene glycol (manufactured by Nippon Shokubai), 14.4 kg of polyethylene glycol having a number average molecular weight of 8300 melted by heating to 70 ° C. (PEG6000S, manufactured by Sanyo Chemical Industries) were sequentially added to the polycondensation tank, and then esterified. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 250 ° C. through a transfer pipe connecting the conversion reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 250 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 30 g of antimony trioxide as a polymerization catalyst, manganese acetate 22 g was added and stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 250 ° C. to 285 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 25 Pa, and then the polymerization reaction was performed for 3 hours. Thereafter, pentaerythritol-tetrakis (3- (3,5-) was added as an antioxidant (added after the start of the polycondensation reaction) to a container having a thickness of 0.2 mm and an internal volume of 500 cm ³ prepared by injection molding a polyethylene terephthalate sheet. Di-t-butyl-4-hydroxyphenol) propionate) (BASF, Irganox 1010) 480 g was added from the top of the reaction vessel, the inside of the polycondensation tank was purged with nitrogen, returned to normal pressure, stirred for 10 minutes, and then polymerized. The reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Using the obtained pellets, a drawn yarn was produced in the same manner as in Example 4.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, by adding an antioxidant after the start of the polycondensation reaction, scattering of the antioxidant under vacuum during the polycondensation reaction and deactivation of the antioxidant due to thermal decomposition are suppressed, and The antioxidant content was high, the time to the rising half-value point was 360 minutes or more, and oxidative decomposition was suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Examples 17-19
In Example 16, the antioxidant added after the start of the polycondensation reaction was used. In Example 17, 2,4,6-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) mesitylene (manufactured by ADEKA) was used. , Adekastab AO-330) 420 g, in Example 18, 1,3,5-tris [[4- (1,1-dimethylethyl) -3-hydroxy-2,6-dimethylphenyl] methyl] -1,3 384 g of 5-triazine-2,4,6 (1H, 3H, 5H) -trione (manufactured by Tokyo Chemical Industry Co., Ltd., THANOX 1790), and in Example 19, dibutylamine-1,3,5-triazine-N, N′-bis ( Polycondensate (BASF) of 2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine CHIMASSORB2020) was changed to 384g were produce a drawn yarn in the same manner as in Example 4.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. When any antioxidant was used, the fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, by adding an antioxidant after the start of the polycondensation reaction for any of the antioxidants, the content of the antioxidant in the fiber is high, the time to the rising half-point is over 360 minutes, It was suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Examples 20-22
In Example 16, an antioxidant was not added before the start of the polycondensation reaction, but pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxy) was added as an antioxidant added after the start of the polycondensation reaction. A drawn yarn was produced in the same manner as in Example 4 except that phenol) propionate) (manufactured by BASF, Irganox 1010) was changed to 480 g in Example 20, 1200 g in Example 21, and 2400 g in Example 22.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the addition amount of the antioxidant added after the start of the polycondensation reaction was changed, the fiber characteristics such as strength and toughness were good, and the U% (hi) was low and the fiber was homogeneous. Furthermore, in any addition amount, the antioxidant content in the fiber was high, the time to the rising half-point was 360 minutes or more, and oxidative degradation was also suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Example 23
In the extruder type spinning machine, the pellets obtained in Example 4 were transferred from the main feeder to pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010). ) Was supplied from the sub-feeder at a weight ratio of 100: 0.4, and a drawn yarn was produced in the same manner as in Example 4.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, by adding an antioxidant at the time of melt spinning, the content of the antioxidant in the fiber was high, the time to the rising half-point was 360 minutes or more, and oxidative degradation was suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Example 24
In the extruder type spinning machine, the pellets prepared without adding the antioxidant before the start of the polycondensation reaction in Example 4 were transferred from the main feeder to pentaerythritol-tetrakis (3- (3,5-di-t-butyl). -4-Hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) was supplied in the same manner as in Example 4 except that a weight ratio of 100: 0.4 was supplied from the sub-feeder.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, by adding an antioxidant at the time of melt spinning, the content of the antioxidant in the fiber was high, the time to the rising half-point was 360 minutes or more, and oxidative degradation was suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Example 25
Citrate chelate titanium complex equivalent to 10 ppm in terms of titanium atom, 82.5 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals), and 49.1 kg of 1,3-propanediol are obtained at a temperature of 240 ° C. In the esterification reaction tank maintained at a pressure of 1.2 × 10 ⁵ Pa, the esterification reaction was performed until the temperature of the distillate fell below 90 ° C. to obtain an esterification reaction product. Subsequently, 16.7 kg of 1,3-propanediol, 16.8 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Chemical Industries) melted by heating to 70 ° C. were sequentially added to the polycondensation tank, followed by esterification. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 240 ° C. through a transfer pipe connecting the reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 240 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 11 g of magnesium acetate tetrahydrate as a polymerization catalyst And stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 240 ° C. to 280 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 40 Pa, and then the polymerization reaction was performed for 3 hours. Thereafter, pentaerythritol-tetrakis (3- (3,5-) was added as an antioxidant (added after the start of the polycondensation reaction) to a container having a thickness of 0.2 mm and an internal volume of 500 cm ³ prepared by injection molding a polypropylene terephthalate sheet. Di-t-butyl-4-hydroxyphenol) propionate) (BASF, Irganox 1010) 480 g was added from the top of the reaction vessel, the inside of the polycondensation tank was purged with nitrogen, returned to normal pressure, stirred for 10 minutes, and then polymerized. The reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Using the obtained pellets, a drawn yarn was produced in the same manner as in Example 14.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the hydrophobic polymer was changed to polypropylene terephthalate, the fiber characteristics such as strength and toughness were good, and U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-value point was 360 minutes or more, and oxidative decomposition was also suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Example 26
Citrate chelate titanium complex equivalent to 10 ppm in terms of titanium atom, 82.5 kg of high-purity terephthalic acid (manufactured by Mitsui Chemicals), and 89.5 kg of 1,4-butanediol are obtained at a temperature of 220 ° C. In the esterification reaction tank maintained at a pressure of 1.2 × 10 ⁵ Pa, the esterification reaction was performed until the temperature of the distillate fell below 90 ° C. to obtain an esterification reaction product. Subsequently, 19.7 kg of 1,4-butanediol, 16.8 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Chemical Industries) heated to 70 ° C. and melted were sequentially added to the polycondensation tank, and then esterified. 110.6 kg of the obtained esterification reaction product was transferred to a polycondensation tank heated to 220 ° C. through a transfer pipe connecting the reaction tank and the polycondensation tank. After completion of the transition, the mixture was stirred at 220 ° C. for 1 hour. Thereafter, 180 g of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming 120 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent, 30 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 11 g of magnesium acetate tetrahydrate as a polymerization catalyst And stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 220 ° C. to 250 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 60 Pa, and then the polymerization reaction was performed for 3 hours. Thereafter, pentaerythritol-tetrakis (3- (3,5) was added as an antioxidant (added after the start of the polycondensation reaction) to a container having a thickness of 0.2 mm and an internal volume of 500 cm ³ prepared by injection molding a polybutylene terephthalate sheet. -Di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) was added from the top of the reaction vessel, the inside of the polycondensation tank was purged with nitrogen, returned to normal pressure, and stirred for 10 minutes. The polymerization reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Using the obtained pellets, a drawn yarn was produced in the same manner as in Example 15.

  Table 4 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the hydrophobic polymer was changed to polybutylene terephthalate, the fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-value point was 360 minutes or more, and oxidative decomposition was also suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Examples 27-36
In the extruder type spinning machine, the pellets produced in Example 1 in Examples 27, 35, and 36, the pellets produced in Example 3 in Example 28, the pellets produced in Example 4 in Examples 29-31, In Example 32, the pellet produced in Example 8, the pellet produced in Example 10 in Example 33, and the pellet produced in Example 11 in Example 34 were fed from the main feeder with pentaerythritol-tetrakis (3- (3,5 -Di-t-butyl-4-hydroxyphenol) propionate) (Irganox 1010, manufactured by BASF) was fed from the sub-feeder at a weight ratio of 100: 0.4. Example 27 was prepared in the same manner as in Example 1. Is the same as Example 3, Example 29 is the same as Example 5, Example 30 is the same as Example 6, Example 31 is the same as Example 7. Similarly, Example 32 is the same as Example 8, Example 33 is the same as Example 10, Example 34 is the same as Example 11, Example 35 is the same as Example 12, Example 36 Produced a drawn yarn in the same manner as in Example 13.

  Table 5 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the number average molecular weight and copolymerization rate of the hydrophilic polymer, the shear rate when passing through the spinneret, and the spinning rate are changed, the fiber properties such as strength and toughness are good, and U% (hi) is low and homogeneous. Fiber. Furthermore, by adding an antioxidant at the time of melt spinning, the content of the antioxidant in the fiber was high, the time to the rising half-point was 360 minutes or more, and oxidative degradation was suppressed. In addition, the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were good, and the leveling property and quality were acceptable.

Example 37
In Example 4, a drawn yarn was produced in the same manner as in Example 4 except that the amount of the antioxidant (added before the start of the polycondensation reaction) was changed to 600 g.

  Table 5 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Regarding the fabric properties, the antistatic property and the hygroscopic property were extremely excellent. Moreover, the weight reduction rate after the hot water treatment was low, elution of the hydrophilic compound was suppressed, and the leveling and quality were acceptable levels.

Example 38
A slurry composed of 8.7 kg of dimethyl terephthalate, dimethyl 5-sodium sulfoisophthalate (SSIA) (manufactured by Sanyo Chemical Industries), and 5.6 kg of ethylene glycol (manufactured by Nippon Shokubai Co., Ltd.) was charged into the transesterification reaction tank. As a result, 21.5 g of lithium acetate dihydrate and 2 g of cobalt acetate tetrahydrate were added, and the transesterification was carried out at 240 ° C. for 2 hours to obtain a transesterification product. Subsequently, 1.2 kg of polyethylene glycol having a number average molecular weight of 8300 (PEG6000S manufactured by Sanyo Kasei Kogyo Co., Ltd.) melted by heating to 70 ° C. was introduced into the polycondensation tank, and then a transition pipe connecting the transesterification reaction tank and the polycondensation tank. The transesterification product obtained was transferred to a polycondensation tank heated to 240 ° C. After completion of the transition, the mixture was stirred at 240 ° C. for 1 hour. Thereafter, 15 g of pentaerythritol-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) as an antioxidant (added before the start of the polycondensation reaction), antifoaming After adding 7 g of silicon (manufactured by Momentive Performance Materials, TSF433) as an agent and 4.3 g of trimethyl phosphate (manufactured by Wako Pure Chemical Industries) as a heat stabilizer and stirring for 10 minutes, 3 g of antimony trioxide as a polymerization catalyst was added. The mixture was further stirred for 5 minutes. Subsequently, the temperature in the polycondensation tank was raised from 240 ° C. to 285 ° C. over 60 minutes, and the pressure in the polycondensation tank was reduced from atmospheric pressure to 25 Pa, and then the polymerization reaction was performed for 3 hours. Then, thickness of 0.2mm was prepared by injection molding a polyethylene terephthalate sheet, the inner volume of 500 cm ^3, of pentaerythritol as an antioxidant (added after the start polycondensation reaction) - tetrakis (3- (3,5 Di-t-butyl-4-hydroxyphenol) propionate) (Irganox 1010 manufactured by BASF) was added from the top of the reaction vessel, the inside of the polycondensation tank was purged with nitrogen, returned to normal pressure, stirred for 10 minutes, and polymerized. The reaction product was discharged into cold water in a strand form, cooled, and immediately cut to obtain a pelletized polymerization reaction product. Using the obtained pellets, a drawn yarn was produced in the same manner as in Example 4. In addition, the SSIA copolymerization rate shown in Table 6 is the ratio of the weight of the sulfur element contained in the polymerization reaction product.

  Table 6 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. The fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-point was 360 minutes or more, the oxidative decomposition was suppressed, and the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were also good. Moreover, since 5-sodium sulfoisophthalic acid was copolymerized, it showed cationic dyeability, and the leveling quality and quality were acceptable levels.

Examples 39 and 40
A drawn yarn was produced in the same manner as in Example 38 except that the copolymerization rate of 5-sodium sulfoisophthalic acid was changed as shown in Table 6.

  Table 6 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the copolymerization ratio of 5-sodium sulfoisophthalic acid was changed, the fiber characteristics such as strength and toughness were good, and U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-point was 360 minutes or more, the oxidative decomposition was suppressed, and the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were also good. Moreover, leveling quality and quality were acceptable levels.

Examples 41 and 42
A drawn yarn was produced in the same manner as in Example 38 except that the copolymerization ratio of the hydrophilic polymer was changed as shown in Table 6.

  Table 6 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. Even when the copolymerization ratio of the hydrophilic polymer was changed, the fiber characteristics such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-point was 360 minutes or more, the oxidative decomposition was suppressed, and the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were also good. Moreover, leveling quality and quality were acceptable levels.

Examples 43-47
In Examples 38 to 42, when the melt spinning was performed without adding an antioxidant after the start of the polycondensation reaction, the pellets obtained in each Example were transferred from the main feeder to the pentaerythritol- Except that tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenol) propionate) (manufactured by BASF, Irganox 1010) was supplied from the sub-feeder at a weight ratio of 100: 0.4, each example and Similarly, a drawn yarn was produced.

  Table 6 shows the evaluation results of the fiber characteristics and fabric characteristics of the obtained fibers. In any case, fiber properties such as strength and toughness were good, U% (hi) was low, and the fiber was homogeneous. Furthermore, the time to the rising half-point was 360 minutes or more, the oxidative decomposition was suppressed, and the antistatic property, hygroscopicity, and the weight reduction rate after the hot water treatment were also good. Moreover, leveling quality and quality were acceptable levels.

  Although the fiber of the present invention has a phase separation structure, the fineness spots are small, the occurrence of dyed spots and fluff is suppressed, and the durability of the fiber characteristics against long-term storage and tumbler drying It is excellent in hygroscopicity and antistatic properties in a low-temperature and low-humidity environment, and the elution of hydrophilic compounds is suppressed during dyeing and use. Therefore, it can be suitably used as a fiber structure such as a woven or knitted fabric or a non-woven fabric for clothing.

Claims (8)

It consists of a copolymer of a hydrophobic polymer and a hydrophilic polymer, has a continuous phase and a dispersed phase due to a phase separation structure, the maximum diameter of the dispersed phase in the fiber cross section is 1 to 40 nm, and the fineness variation value U % (hi) is Ri from 0.1 to 1.5% der, the hydrophobic polymer is polyester, fibers having a phase separation structure in which the hydrophilic polymer is characterized Oh Rukoto with polyethylene glycol.   The fiber according to claim 1, wherein the copolymer of the hydrophobic polymer and the hydrophilic polymer is exposed on at least a part of the fiber surface. Based on JIS L1094, temperature 10 ° C., the fibers according to claim 1 or 2, wherein the frictional electrification voltage was measured at a humidity 10% RH is less than 3000 V. The fiber was heated from room temperature to 160 ° C. at a mixed gas flow rate of 200 mL / min and a heating rate of 30 ° C./min in a mixed gas atmosphere of nitrogen: oxygen = 80 vol%: 20 vol%, and maintained at 160 ° C. when the derivative thermal gravimetric analysis (DTG), to 0 minutes time has been reached 160 ° C., according to claim 1 any one claim of 3 time to rise half point, characterized in that at least 120 minutes Fiber. An antioxidant is contained, The fiber as described in any one of Claims 1-4 characterized by the above-mentioned. The antioxidant, phenolic compounds, sulfur compounds, fibers according to claim 5, wherein the at least one selected from the hindered amine compound. The fiber according to claim 5 or 6, wherein the content of the antioxidant is 0.01 to 2.0% by weight of the fiber weight. Claim 1-7, characterized in that the shear rate at which the copolymer of the hydrophobic polymer and a hydrophilic polymer to pass through the spinneret is spun so as to 10000～40000S ^-1 A method for producing a fiber according to one item.

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