JP5239454B2 - Liquid crystal polyester fiber and method for producing the same - Google Patents

Description

  The present invention relates to a liquid crystal polyester fiber having a high strength and a high elastic modulus and excellent in workability in a high-order processing step and having few defects and fibrils, and a method for producing the same.

  Liquid crystalline polyester fibers have extremely high strength and elastic modulus compared to general-purpose fibers because rigid molecular chains are highly oriented in the fiber axis direction, and are further solidified by heat treatment in fiber form. The polymerization reaction proceeds, and the degree of polymerization of the liquid crystal polyester can be increased to further improve the performance. At this time, in order to increase the processing amount per unit time, a method of performing solid phase polymerization using fibers as a package shape is widely used industrially.

  However, fusion between single yarns is likely to occur in the temperature range near the melting point where the solid-state polymerization reaction can proceed, and the fused part of the fiber surface is peeled off during unwinding from the package, resulting in fusing marks and fibrillation. Defects such as starting points are likely to occur. In addition, the liquid crystalline polyester fiber has a rigid molecular chain highly oriented in the fiber axis direction and has a low interaction in the fiber axis vertical direction, and thus fibrils may be generated starting from such defects. The occurrence of defects and fibrils causes deterioration of fiber properties, deterioration of workability in higher processing steps, and deterioration of product quality and performance.

  As a method for solving these problems, a liquid crystal polyester manufacturing method (patented) is characterized by attaching a surfactant containing a C 3-20 perfluoroalkyl group to a liquid crystal polyester fiber and then heat-treating the fiber. Document 1) has been proposed. However, although the liquid crystal polyester fiber suppresses fusion and reduces the occurrence of defects and fibrils, the fiber surface has not improved smoothness, and is fibrillated by friction at the yarn path guide in the subsequent higher processing step. It is easy, and the obtained fiber has many fibrils.

  In addition, a method for producing liquid crystal polyester fiber, characterized in that an organic polymer powder having a melting point or softening temperature equal to or higher than the heat treatment temperature is attached to the liquid crystal polyester fiber, followed by heat treatment (see Patent Document 2). . However, the liquid crystalline polyester fiber has an insufficient effect of suppressing fusion, and the organic polymer powder adhered by contact with a traveling guide or the like in the subsequent high-order processing step becomes scum, resulting in deterioration of workability. there were.

On the other hand, a liquid crystal polyester monofilament having a strength of 12 g / d or more and an elastic modulus of 300 g / d or more, in which 1% by weight or more of polysiloxane and / or fluororesin is adhered has been proposed (see Patent Document 3). The purpose of Patent Document 3 is to improve wear resistance and weaving properties by attaching polysiloxane and / or fluorine-based resin to the surface of the liquid crystal polyester fiber. However, since the size of the adhering fluororesin is large, the fluororesin becomes a scum due to contact with a traveling guide or the like in the subsequent high-order processing step, and there is a disadvantage that the workability deteriorates.
JP 63-99328 A (Claim 2) JP-A-61-296185 (Claim 1) JP-A-11-269737 (Claim 2)

  An object of the present invention is to provide a liquid crystal polyester fiber having few defects and fibrils, which does not cause fusion between single yarns even when solid phase polymerization is performed in a package shape, and is excellent in workability in a high-order processing step. .

The above-mentioned problem can be solved by attaching a fluorine compound having 40 or less carbon atoms and a polysiloxane to fibers obtained by melt spinning a liquid crystalline polyester and then performing solid phase polymerization for 5 hours or more .

  Even when solid phase polymerization is performed in a package shape by applying a fluorine compound having 40 or less carbon atoms and polysiloxane, there is no fusion between single yarns, and since polysiloxane is present on the fiber surface, A liquid crystal polyester fiber having excellent processability can be produced. The liquid crystal polyester fibers obtained in this way can be used for cord reinforcement materials, protective gloves, plastic reinforcement materials, optical fiber tension members, etc. for various electrical products. Since it is excellent in processability in the process and has few defects and fibrils and is suitable as a monofilament, it can be suitably used for screen wrinkles where a high mesh fabric is required.

  The liquid crystal polyester used in the present invention refers to a polyester that exhibits optical anisotropy (liquid crystallinity) when heated and melted. This can be recognized by placing a sample made of liquid crystalline polyester on a hot stage, heating and heating in a nitrogen atmosphere, and observing the transmitted light of the sample with a polarizing microscope.

  Examples of the liquid crystal polyester used in the present invention include (a) a polymer of aromatic oxycarboxylic acid, (b) a polymer of aromatic dicarboxylic acid and aromatic diol, and aliphatic diol, (c) (a) and ( The copolymer of b) etc. are mentioned, The polymer comprised only by the aromatic is especially preferable. Polymers composed only of aromatics exhibit excellent strength and elastic modulus when made into fibers. Moreover, conventionally well-known method can be used for the polymerization prescription of liquid crystalline polyester.

  Here, examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid, hydroxynaphthoic acid and the like, or alkyl, alkoxy and halogen substituted products thereof.

  Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylethanedicarboxylic acid, and the like, or alkyl, alkoxy, and halogen substitution thereof. Examples include the body.

  Furthermore, examples of the aromatic diol include hydroquinone, resorcin, dihydroxybiphenyl, naphthalene diol, and the like, or alkyl, alkoxy, and halogen-substituted products thereof. Examples of the aliphatic diol include ethylene glycol, propylene glycol, and butanediol. And neopentyl glycol.

  In addition to the above monomers, the liquid crystal polyester used in the present invention can be copolymerized with other monomers as long as the liquid crystallinity is not impaired. Examples include adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Examples include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, polyethers such as polyethylene glycol, polysiloxanes, aromatic iminocarboxylic acids, aromatic diimines, and aromatic hydroxyimines.

  Preferable examples of the liquid crystal polyester obtained by polymerizing the monomers and the like used in the present invention include (A) a liquid crystal polyester obtained by copolymerizing a p-hydroxybenzoic acid component and a 6-hydroxy-2-naphthoic acid component, and (B) p- Examples thereof include liquid crystal polyesters in which a hydroxybenzoic acid component, a 4,4′-dihydroxybiphenyl component, an isophthalic acid component and / or a terephthalic acid component are copolymerized, and (C) a p-hydroxybenzoic acid component and 4, Examples thereof include liquid crystal polyesters in which a 4'-dihydroxybiphenyl component, an isophthalic acid component, a terephthalic acid component, and a hydroquinone component are copolymerized.

  The combination of the above (A), (B), and (C) causes the molecular chain to have appropriate crystallinity and nonlinearity, that is, a melting point capable of being melt-spun. Therefore, the fiber has a good spinning property at the spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, and a uniform fiber is obtained in the longitudinal direction. The rate can be increased.

  The polystyrene equivalent weight average molecular weight (hereinafter referred to as molecular weight) of the liquid crystalline polyester used in the present invention is preferably 30,000 or more, and more preferably 50,000 or more. By setting the molecular weight to 30,000 or more, an appropriate viscosity can be obtained at the spinning temperature and the spinning property can be improved. The higher the molecular weight, the higher the strength, elongation, and elastic modulus of the obtained fiber. On the other hand, if the molecular weight is too high, the viscosity becomes high, the fluidity becomes poor, and eventually the fluid does not flow. Therefore, the molecular weight is preferably less than 250,000, more preferably less than 150,000.

The melting point of the liquid crystalline polyester of the present invention is preferably in the range of 200 to 380 ° C., more preferably 250 to 350 ° C., more preferably 290 to 340 ° C. from the viewpoint of melt spinning and heat resistance. is there. The melting point is observed in a differential scanning calorimeter in differential calorimetry carried out at (Perkin Elmer DSC), an endothermic peak temperature observed upon raising the temperature condition measurements 20 ° C. / min from 50 ° C. (Tm ₁₎ Then, after holding at a temperature of about Tm ₁ + 20 ° C. for 5 minutes, the temperature is decreased to 50 ° C. at a rate of temperature decrease of 20 ° C./min, and the endothermic peak temperature observed when measured again at a temperature increase condition of 20 ° C./min (Tm ₂ ) was defined as the melting point.

  In addition, other polymers can be added to and used in combination with the liquid crystalline polyester used in the present invention as long as the effects of the present invention are not impaired. Addition / combination means mixing two or more polymers, using one component or two or more components partially mixed in a composite spinning of two or more components, or using all of them. Say. Examples of other polymers include polyester, vinyl polymers such as polyolefin and polystyrene, polycarbonate, polyamide, polyimide, polyphenylene sulfide, polyphenylene oxide, polysulfone, aromatic polyketone, aliphatic polyketone, semi-aromatic polyesteramide, and polyether. Polymers such as ether ketone and fluororesin may be added, such as polyphenylene sulfide, polyether ether ketone, nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. Preferred examples include phthalate, polycyclohexanedimethanol terephthalate, and polyester 99M. In addition, when these polymers are added and used in combination, it is preferable that the melting point is within the melting point of the liquid crystal polyester ± 30 ° C. so as not to impair the spinning property, and to improve the strength and elastic modulus of the obtained fiber. Is preferably added or used in an amount of 50% by weight or less, more preferably 5% by weight or less, and most preferably no other polymer is added or used in combination.

  The liquid crystalline polyester used in the present invention includes various metal oxides, inorganic substances such as kaolin and silica, colorants, matting agents, flame retardants, antioxidants and ultraviolet absorbers within the range not impairing the effects of the present invention. In addition, additives such as infrared absorbers, crystal nucleating agents, fluorescent brighteners, end group capping agents, and compatibilizers may be contained in small amounts.

  In melt spinning, a known method can be used for melt extrusion of liquid crystal polyester, but an extruder type extruder is preferably used in order to eliminate the ordered structure generated during polymerization. The extruded polymer is measured by a known measuring device such as a gear pump via a pipe, and after passing through a filter for removing foreign matter, is guided to a base. At this time, the temperature from the polymer pipe to the die (spinning temperature) is preferably not lower than the melting point of the liquid crystalline polyester and not higher than the thermal decomposition temperature, more preferably not lower than the melting point of the liquid crystalline polyester + 10 ° C. or higher and 400 ° C. or lower. More preferably, the melting point is + 20 ° C. or higher and 370 ° C. or lower. It is also possible to independently adjust the temperature from the polymer pipe to the base. In this case, the discharge is stabilized by making the temperature of the part close to the base higher than the temperature on the upstream side.

  In addition, in order to obtain the liquid crystal polyester fiber of the present invention, it is better to improve the stability at the time of discharge and the stability of the thinning behavior. In industrial melt spinning, one is necessary to reduce energy cost and improve productivity. Since a large number of base holes are perforated in the base, it is better to stabilize the discharge and thinning of each hole.

  In order to achieve this, it is preferable to reduce the diameter of the base hole and increase the land length (the length of the straight pipe portion equal to the diameter of the base hole). However, when the hole diameter is excessively small, clogging of the hole is likely to occur, so that the diameter is preferably 0.03 mm or more and 0.30 mm or less, more preferably 0.05 mm or more and 0.25 mm or less, and 0.08 mm or more and 0.20 mm. The following is more preferable. If the land length is excessively long, the pressure loss becomes high, so that L / D defined by the quotient obtained by dividing the land length L by the hole diameter D is preferably 0.5 or more and 3.0 or less, preferably 0.8 or more. 5 or less is more preferable, 1.0 or more and 2.0 or less are still more preferable. In order to maintain uniformity, the number of holes in one die is preferably 50 holes or less, more preferably 40 holes or less, and even more preferably 20 holes or less. In addition, it is preferable that the introduction hole located immediately above the die hole is a straight hole having a diameter of 5 times or more the diameter of the die hole in terms of not increasing pressure loss. It is preferable to taper the connection part between the introduction hole and the base hole in order to suppress abnormal stagnation. However, the length of the taper part should be less than twice the land length without increasing pressure loss and stabilizing the streamline. This is preferable.

  The polymer discharged from the base hole passes through a heat retaining and cooling region and solidifies, and is then taken up by a roller (godet roller) that rotates at a constant speed. If the heat-retaining region is excessively long, the yarn forming property is deteriorated, so that it is preferably up to 200 mm from the base surface, and more preferably up to 100 mm. In the heat retaining region, it is possible to increase the ambient temperature using a heating means, and the temperature range is preferably 100 ° C. or higher and 500 ° C. or lower, more preferably 200 ° C. or higher and 400 ° C. or lower. For the cooling, an inert gas, air, water vapor or the like can be used. However, it is preferable to use a parallel or annular air flow from the viewpoint of reducing the environmental load.

  The take-up speed is preferably 50 m / min or more, more preferably 300 m / min or more, and further preferably 500 m / min or more in order to reduce productivity and single yarn fineness. Since the liquid crystalline polyester used in the present invention has a suitable spinnability at the spinning temperature, the take-up speed can be increased. Although the upper limit is not particularly limited, the liquid crystal polyester used in the present invention is about 2000 m / min from the viewpoint of spinnability.

  The spinning draft defined by the quotient obtained by dividing the take-up speed by the discharge linear speed is preferably 1 or more and 500 or less, more preferably 5 or more and 200 or less, and still more preferably 12 or more and 100 or less. Since the liquid crystalline polyester used in the present invention has suitable spinnability, the draft can be increased, which is advantageous for fineness.

  Winding can be carried out by using a known winder to form a package of a shape such as pirn, cheese, corn, etc. However, it is preferable that the wrapping is performed so that the roller does not contact the surface of the package during winding.

  The liquid crystal polyester fiber thus obtained needs to be subjected to solid phase polymerization in order to further improve the strength and elastic modulus. Solid-phase polymerization can be processed into a package shape, a crushed shape, a tow shape (for example, on a metal net) or continuously as a thread between rollers, but the equipment can be simplified and produced. It is preferable to use a package shape from the viewpoint of improving the performance.

  When solid phase polymerization is performed in a package shape, a technique for preventing fusion that becomes noticeable when the single fiber fineness is reduced is required.

  An important point of the present invention is that a fluorine compound having 40 or less carbon atoms and polysiloxane are adhered to the surface of the liquid crystal polyester fiber before solid phase polymerization. When only the fluorine compound is attached, the fusion is suppressed and the generation of defects and fibrils is reduced, but the smoothness of the fiber surface is not improved, and the yarn path guide in the subsequent higher processing step is not improved. The fibers are easily fibrillated by friction, and the resulting fibers are rich in fibrils. In addition, as a result of intensive studies, the present inventors have found that polysiloxane imparted to the fiber to improve electrical insulation and smoothness usually has a fusion-inhibiting effect, but only polysiloxane is adhered. In this case, the polysiloxane flows due to the winding tension of the package and the single yarns come into contact with each other, so the effect of suppressing fusion is low, and the resulting fiber has many defects and fibrils. However, when both the fluorine compound and polysiloxane are applied to the fiber surface, the fiber surface is covered with polysiloxane, and the fluidity of the fiber surface is lowered to maintain some fluidity even when subjected to the heat of solid phase polymerization. In addition, the running friction on the yarn path guide in the high-order processing step is reduced, and the fluorine compound is fixed to the fiber with an appropriate strength, so that it is difficult to fall off. Furthermore, polysiloxane is effective for suppressing fusion, and the effect of suppressing fusion is higher than when only a fluorine compound is adhered.

The fluorine compound used in the present invention is a known fluorine compound. Among them, a compound containing a fluoroalkyl group or a fluoroalkenyl group is preferable because it has an excellent anti-fusing effect, and a compound containing a perfluoroalkyl group is preferred. More preferred. The carbon number of the fluoroalkyl group or fluoroalkenyl group is preferably 1 to 21, particularly 1 to 8, for example 1 to 6. Examples of fluoroalkyl _{group, -CF 3, -CF 2 CF 3} , -CF 2 CF 2 CF 3, -CF (CF 3) 2, -CF 2 CF 2 CF 2 CF 3, -CF 2 CF (CF 3 ) ₂ , —C (CF ₃ ) ₃ , — (CF ₂ ) ₄ CF ₃ , — (CF ₂ ) ₂ CF (CF ₃ ) ₂ , —CF ₂ C (CF ₃ ) ₃ , —CF (CF ₃ ) CF ₂ CF ₂ CF ₃ ,-(CF ₂ ) ₅ CF ₃ ,-(CF ₂ ) ₃ CF (CF ₃ ) ₂ ,-(CF ₂ ) ₄ CF (CF ₃ ) ₂ ,-(CF ₂ ) ₇ CF ₃ , _{- (CF 2) 5 CF (} CF 3) 2, - (CF 2) 6 CF (CF 3) 2, - a _{(CF 2)} 9 CF ₃ and the like. The fluorine compound is preferably a surfactant having a hydrophilic group from the viewpoint of water dispersibility. Examples of the hydrophilic component include anion types such as phosphates, carboxylates, sulfonates, sulfosuccinates and sulfate esters, cationic types such as ammonium salts, nonionic types having a polyoxyethylene group, and betaines. And zwitterionic type. Examples thereof include perfluoroalkyl group-containing phosphate ester salts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl polyoxyethylene, perfluoroalkyl betaine, and the like. As fluorine-based phosphate ester salts, metal salts such as sodium, potassium, lithium, magnesium, calcium, ammonium, rubidium, and ammonium salts are easy to obtain and handle and can be finely dispersed in water. preferable.

  Moreover, it is important that the fluorine compound used in the present invention has 40 or less carbon atoms. When the number of carbon atoms exceeds 40, the price is very high and uneconomical, and it is difficult to disperse in a solvent when it is attached to a fiber as a solution or dispersion, or the dispersion diameter becomes large even if dispersed. Therefore, the carbon number is preferably 40 or less, and more preferably 30 or less, because uniform adhesion to the fiber surface becomes difficult. In addition, the lower limit of the carbon number of the fluorine compound is not particularly limited, but generally the lower the carbon number, the lower the decomposition temperature of the fluorine compound and the chemical activation. Is preferable, and 5 or more is more preferable.

  As a method for attaching the fluorine compound to the liquid crystal polyester fiber, a method in which the fluorine compound is uniformly attached to the fiber is preferable in order to prevent fusion between the fibers. For example, a method in which a solution in which the fluorine compound in the present invention is dispersed in a solvent such as water is attached to fibers using an oiling roller or an oiling guide can be mentioned. As the solvent for dispersing the fluorine compound, water is preferable because it is easy to handle and has a small environmental load. As an example, when a fluorine-based phosphate ammonium salt is used as the fluorine compound, when dispersed in water, it becomes a uniform solution without precipitation, and when this is attached to the fiber using an oiling roller or oiling guide, the fiber surface is It is suitable for uniformly covering and preventing fusion.

  When the fluorine compound is dispersed in water, various surfactants may be added to further stabilize the dispersion state. As the surfactant, for example, as an anionic surfactant, fatty acid salt, alpha sulfo fatty acid ester salt, alkylbenzene sulfonate, linear alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate, alkyl sulfate triethanolamine, Alkyl phosphate ester, fatty acid diethanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylphenyl ether, polyoxyethylene isotridecyl ether, polyoxy as nonionic surfactant Ethylenepropyl tridecyl ether, sorbitan alkyl ester, higher amine halogenate, alkyltrimethylammonium salt as cationic surfactant, Alkyl dimethyl ammonium chloride, alkyl pyridinium chloride, alkyl carboxy betaine and mixtures thereof as amphoteric surfactants. Among these, nonionic surfactants are preferable from the viewpoint of dispersion stability, and polyoxyethylene ethers such as polyoxyethylene alkylphenyl ether, polyoxyethylene isotridecyl ether, and polyoxyethylene propyl tridecyl ether are more preferable.

The polysiloxane used in the present invention is composed of a repeating unit represented by the following formula, wherein R ₁ and R ₂ are a hydrogen atom, an alkyl group such as —CH ₃ and —CH ₂ CH _3, or —C ₆ H _5, etc. An aryl group of n is an integer of 2 to 10,000.

  The polysiloxane used in the present invention is a surface treatment agent that imparts smoothness, a fusion suppression effect, and the like to the fiber, and can improve the workability in the higher-order processing step by being applied.

  The polysiloxane used in the present invention is preferably an oily polysiloxane such as polydimethylsiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, or a modified product thereof, because uniform adhesion to fibers is easy. Of these, non-reactive polysiloxanes, which are unlikely to undergo a crosslinking reaction by the heat of solid phase polymerization, are more preferred. Non-reactive polysiloxanes include polydimethylsiloxane, polyphenylmethylsiloxane, or their polyether-modified products, methylstyryl-modified products, alkyl-modified products, higher fatty acid ester-modified products, hydrophilic special-modified products, and fluorine-modified products. Products and higher fatty acid-containing materials. The viscosity (25 ° C.) is preferably 1 to 30,000 cSt, and more preferably 10 to 10,000 cSt. By setting it to 1 cSt or more, the flash point is high and handling becomes easy, and by setting it to 30,000 cSt or less, uniform application to the fiber is facilitated. Furthermore, in order to improve heat resistance, you may mix | blend well-known heat resistance improvers, such as an organic acid metal salt and an aromatic amine compound.

  The method of attaching polysiloxane to the liquid crystal polyester fiber is preferably uniformly attached to the fiber. For example, when the polysiloxane is a liquid, there can be mentioned a method in which nonionic, anionic and cationic emulsifiers are used to emulsify the polysiloxane in water using an oiling roller or an oiling guide. . The polysiloxane used at this time is preferably polydimethylsiloxane which is easily emulsified and has low reactivity and excellent smoothness.

  The fluorine compound and the polysiloxane may be attached separately, but from the viewpoint of controlling the amount of attachment and simplicity, a method of attaching in the same bath is preferable. For example, there is a method in which a solution in which a solution in which a fluorine compound is dispersed and a water-based emulsion obtained by emulsifying polysiloxane in water using an emulsifier is mixed is attached to fibers using an oiling roller or an oiling guide. In addition, the solution may contain surfactants used for ordinary spinning oils and various additives for accelerating the solid-state polymerization reaction as long as they do not interfere with dispersion and emulsion. Absent.

  Adhesion of the fluorine compound and polysiloxane to the liquid crystal polyester fiber in the present invention must be performed before solid phase polymerization. For example, the method of adhering the polymer while it is wound from the nozzle after discharging from the nozzle is preferable in terms of simplicity, and adheres to the fiber while the wound fiber is rewound and processed into a desired solid-phase polymerization shape. This method is preferable because the adhesion amount can be easily controlled. In addition, before and after attaching the fluorine compound and polysiloxane, various kinds of surfactants and solid-state polymerization reactions that are used for ordinary spinning oils are used so long as they do not interfere with the adhesion of the fluorine compound and polysiloxane. Additives may be attached.

The adhesion amount (A wt%) of the fluorine compound and the adhesion amount (B wt%) of the polysiloxane with respect to the weight of the liquid crystalline polyester fiber of the present invention preferably satisfy the following conditions 1 to 3.
Condition 1.2.0 ≦ 2 × A + B ≦ 20
Condition 2. A ≧ 0.1
Condition 3. B / A ≧ 1/3
In the above condition 1, it is preferable to be 2.0 or more in order to obtain a high fusion suppressing effect, and 20 or less is preferable and 10 or less is more preferable to suppress the manufacturing cost. In order to obtain the effect of suppressing the fusion of the fluorine compound, it is preferable that the amount of the fluorine compound attached is 0.1% by weight or more (Condition 2). Furthermore, by satisfying Condition 3, polysiloxane that can cover the fluorine compound can be present on the fiber surface, so that the smoothness of the fiber surface is improved, and defects and fibrils are less likely to occur in the higher processing step, The fiber has excellent processability.

In addition, the adhesion amount of the deposit | attachment in this invention can be measured with the adhesion amount measuring method of the deposit | attachment described in the Example. Further, the components of the deposit can be identified by selecting the cleaning liquid after ultrasonic cleaning and / or the dried and evaporated water according to the purpose from the following items, or by combining these.
(1) X-ray fluorescence analysis (elemental analysis)
(2) X-ray diffraction (powder method or orientation method)
(3) NMR
(4) Infrared absorption spectrum measurement (5) Inspection thermal analysis (6) SEM observation Further, in order to prevent fusion at the time of solid phase polymerization, it is a preferred embodiment that the winding density is 0.15 g / cm ³ or less. Yes, and more preferably 0.10 g / cm ³ or less. Here, the winding density is a value calculated by Wf / Vf from the occupied volume (Vf) of the package and the weight (Wf) of the fiber obtained from the dimensions of the package and the bobbin serving as the core material. The smaller the winding density, the weaker the adhesion between the fibers in the package, so that the fusion can be suppressed. If the winding density is excessively small, the package is collapsed, and therefore it is preferably 0.03 g / cm ³ or more.

  Such a package having a low winding density may be formed by winding in melt spinning. However, it is preferable to wind and form a package wound by melt spinning because the winding density can be further reduced. In the rewinding, the winding density can be reduced as the winding tension is reduced. Therefore, the winding tension is preferably 0.10 cN / dtex or less, and more preferably 0.05 cN / dtex or less. Further, in order to form a stable package even in the case of low tension winding, the winding shape is preferably a taper end winding with both ends tapered. Furthermore, in winding, the traverse width is periodically swung with respect to time, whereby a package excellent in handling and unwinding can be obtained.

  Solid-phase polymerization can be carried out in an inert gas atmosphere such as nitrogen, an oxygen-containing active gas atmosphere such as air, or under reduced pressure, but it can simplify equipment and prevent oxidation of fibers or deposits. Therefore, it is preferable to carry out in a nitrogen atmosphere. At this time, the atmosphere of the solid phase polymerization is preferably a low-humidity gas having a dew point of −40 ° C. or less.

The solid phase polymerization temperature is preferably not lower than the melting point of the liquid crystalline polyester fiber subjected to solid phase polymerization at −60 ° C. By setting the temperature close to the melting point, solid phase polymerization proceeds promptly. Moreover, since the melting point of the liquid crystal polyester fiber increases with the progress of the solid phase polymerization, the solid phase polymerization temperature can be increased to the melting point of the liquid crystal polyester fiber subjected to the solid phase polymerization + about 100 ° C. Increasing the solid-phase polymerization temperature stepwise or continuously with respect to time is more preferable because it can prevent fusion and increase the time efficiency of solid-phase polymerization. At this time, the solid phase polymerization is carried out for several minutes to several tens of hours depending on the target performance, but in order to obtain fibers having excellent strength and elastic modulus, the maximum temperature is preferably 5 hours or more , more preferably 10 hours or more. Further, since the solid phase polymerization reaction saturates with the passage of time, about 100 hours is sufficient.

  The package after the solid phase polymerization can be used as a product as it is, but it is preferable to increase the winding density by rewinding the package after the solid phase polymerization in order to increase the product transport efficiency. During rewinding after solid-phase polymerization, the solid-state polymerization package is prevented from collapsing due to unraveling, and the solid-state polymerization package is rotated while rotating the solid-state polymerization package to prevent fibrillation when peeling a slight fusion. It is preferable that the yarn is unwound by so-called side-drawing in which the yarn is unwound in the direction (fiber circulation direction), and the solid-phase polymerization package is preferably rotated by positive driving rather than free rotation.

  When deposits such as fluorine compounds and polysiloxane are excessively attached to the liquid crystal polyester fiber after solid phase polymerization, washing may be performed to remove them. Examples of the cleaning method include a method in which the fiber is contacted with a solvent such as water and a method of wiping with a cloth after the fiber is unwound from the package and wound up. When using a solvent for washing, it is preferable to use water as the solvent because it is easy to handle and has a low environmental impact. In order to increase the cleaning efficiency, a method of shaking and bubbling the solvent or a method of ultrasonic vibration is more preferable. Further, the contact time with the solvent is preferably 0.3 seconds or more, and more preferably 0.5 seconds or more in order to increase the cleaning efficiency. The fibers washed in this manner are free from deposits that easily fall off in the higher-order processing step, and the workability is further improved.

  Moreover, the liquid crystalline polyester fiber in the present invention may be provided with various finishing oils according to the purpose.

  The manufacturing method of the liquid crystalline polyester fiber of this invention is applicable to both a multifilament and a monofilament. In particular, it is suitable for monofilaments in which deterioration of fiber properties due to defects and fibrils, and deterioration of workability in higher processing steps are remarkable.

  The molecular weight in terms of polystyrene after solid phase polymerization of the liquid crystalline polyester fiber of the present invention is preferably 250,000 to 1,500,000. Having a high molecular weight of 250,000 or more has high strength, elongation, and elastic modulus, and improves fabric performance. In addition, when it is made finer, impact absorption is increased and yarn breakage in higher-order processes is suppressed. And wear resistance is improved. Moreover, since it has a high melting point, it has excellent heat resistance. Since these characteristics improve as the molecular weight increases, 300,000 or more is preferable, and 350,000 or more is more preferable. The upper limit of the molecular weight is not particularly limited, but the upper limit that can be reached in the present invention is about 1.5 million. The molecular weight referred to in the present invention is a value determined by the method described in the examples.

  The single fiber fineness after the solid phase polymerization of the liquid crystalline polyester fiber of the present invention is preferably 18.0 dtex or less. By reducing the single fiber fineness to 18.0 dtex or less, the flexibility of the fibers is improved, the processability of the fibers is improved, and the surface area is increased, so that the adhesiveness with a chemical such as an adhesive is increased. In addition to having a monofilament wrinkle, the thickness can be reduced and the woven density can be increased. The single fiber fineness is preferably 10.0 dtex or less, more preferably 7.0 dtex or less.

  The strength after solid phase polymerization of the liquid crystalline polyester fiber of the present invention is 10.0 cN / dtex or more, preferably 12.0 cN / dtex or more, and more preferably 15.0 cN / dtex or more. The upper limit of the strength is not particularly limited, but the upper limit that can be achieved in the present invention is about 30.0 cN / dtex. In addition, the strength said by this invention points out the tensile strength by the strong elongation and elastic modulus measurement described in the Example.

  The elongation after solid phase polymerization of the liquid crystalline polyester fiber of the present invention is 1.0% or more, preferably 2.0% or more. When the elongation is 1.0% or more, the impact absorbability of the fiber is increased, and the process passability and handleability in the high-order processing step are excellent. The upper limit of the elongation is not particularly limited, but the upper limit that can be reached in the present invention is about 5.0%. In addition, the elongation said by this invention points out the breaking elongation by the strong elongation and elastic modulus measurement described in the Example.

  Moreover, the elastic modulus after solid-phase polymerization of the liquid crystalline polyester fiber of the present invention is 500 cN / dtex or more, preferably 600 cN / dtex or more, and more preferably 700 cN / dtex or more. The upper limit of the elastic modulus is not particularly limited, but the upper limit that can be achieved in the present invention is about the elastic modulus of 1200 cN / dtex. In addition, the elasticity modulus said by this invention points out the initial stage tensile resistance degree in the strong elongation and elastic modulus measurement described in the Example.

  The liquid crystalline polyester fiber of the present invention may have any shape such as multifilament, monofilament, staple fiber, cut fiber. Moreover, it can utilize as textiles structures, such as a textile fabric, a knitted fabric, a nonwoven fabric, a braid. In particular, it is a fiber that has high strength, high elastic modulus, few defects and fibrils, and excellent workability in high-order processing, and is therefore suitable as a monofilament. As an example, when the monofilament according to the present invention is applied to a screen ridge using conventional polyethylene terephthalate fiber or the like, the adhering material is less likely to fall off, so that it is excellent in weaving, has few defects, and has excellent strength, elastic modulus and dimensions. A stable screen can be obtained.

  In addition to the above uses, the liquid crystal polyester fiber of the present invention can be used for general industrial materials, civil engineering / building materials, sports applications, protective clothing, rubber reinforcement materials, electrical materials (especially as tension members), acoustic materials, general clothing, etc. Widely used in the field. Effective applications include screen kites, filters, ropes, nets, fishnets, computer ribbons, printed circuit board base fabrics, paper canvases, air bags, airships, dome base fabrics, rider suits, fishing lines, various lines (Yachts, paragliders, balloons, kites), blind cords, support cords for screen doors, various cords for automobiles and aircraft, force transmission cords for electrical products and robots, especially textiles for industrial materials made of monofilaments, especially filters And screens for printing.

  Next, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto. In addition, the measuring method of the physical property quoted in the Example is shown below.

A. Fineness, single fiber fineness 100 m of the fiber was removed with a measuring instrument, the weight (g) was multiplied by 100, 10 measurements were performed per level, and the average value was defined as the fineness (dtex). The quotient obtained by dividing this by the number of filaments was defined as the single fiber fineness (dtex).

B. Strength and elasticity modulus Measured using Tensilon UCT-100 manufactured by Orientec Corporation according to JIS L1013 (1999) except that the sample length was 100 mm and the tensile speed was 50 mm / min.

C. Unraveling unfolded for 100 minutes at a unwinding speed of 200 m / min. ○ for those with almost no resistance, △ for those with light fusion and local resistance, but with △ The case where thread breakage due to wearing occurred was marked with x.

D. Process passability evaluation (workability evaluation), package quality evaluation The sample is applied to a ceramic guide with a tension of 2 cN / dtex and a speed of 200 m / min at 90 °, wound by a winder, and passed for 100 minutes to the ceramic guide. Deposits and fibrils were confirmed. At this time, ◯ indicates that no deposits or fibril deposits were observed, △ indicates that deposits or fibril deposits were seen but passed 100 minutes without thread breakage, and Δ indicates deposits or fibril deposits. The case where thread breakage occurred due to the influence was marked with “x”. In addition, the quality was evaluated from the number of defects due to scum and fibril mixing in the rolled-up package, and three or less in the package were evaluated as good (◯) and four or more as defective (x).

E. Amount of deposits 1000 m of fiber was removed with a measuring instrument, and the weight was measured. Then, the cassette was immersed in 100 ml of water and washed with an ultrasonic cleaner for 1 hour. Thereafter, the weight after ultrasonic cleaning was measured, and the quotient obtained by dividing the difference between the weight before cleaning and the weight after cleaning by the weight before cleaning was defined as the amount of deposit.

Reference example 1
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 157 parts by weight of isophthalic acid, 292 parts by weight of terephthalic acid, 89 parts by weight of hydroquinone Then, 1433 parts by weight of acetic anhydride (1.08 equivalent of the total phenolic hydroxyl groups) was added, and the temperature was raised from room temperature to 145 ° C. over 30 minutes with stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 330 degreeC in 4 hours.

The polymerization temperature was maintained at 330 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.5 hours, and the reaction was continued for another 20 minutes. When the predetermined torque was reached, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

This liquid crystal polyester (Reference Example 1) has 54 mol% of p-hydroxybenzoic acid units, 16 mol% of 4,4'-dihydroxybiphenyl units, 8 mol% of isophthalic acid units, 15 mol% of terephthalic acid units, and hydroquinone units. The melt viscosity was 318 ° C., and the melt viscosity measured at a temperature of 328 ° C. and a shear rate of 1000 / sec using a Koka flow tester was 16 Pa · sec. The molecular weight was 91000. The molecular weight was measured using a mixed solvent of pentafluorophenol / chloroform = 35/65 (weight ratio) as a solvent, and dissolved so that the concentration of the liquid crystal polyester was 0.04 to 0.08 weight / volume%. This was used as a GPC measurement sample, which was measured using a Waters GPC measurement device, and the molecular weight was determined in terms of polystyrene.
Column: 2 Shodex K-806M, 1 K-802 Detector: Differential refractive index detector RI (type 2414)
Temperature: 23 ± 2 ° C
Flow rate: 0.8 mL / min Injection volume: 200 μL
Reference example 2
In a 5 L reaction vessel equipped with a stirring blade and a distilling tube, 907 parts by weight of p-hydroxybenzoic acid, 457 parts by weight of 6-hydroxy-2-naphthoic acid and 946 parts by weight of acetic anhydride (one phenolic hydroxyl group in total) 0.03 molar equivalent) was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and the temperature was raised from room temperature to 145 ° C. over 30 minutes while stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 325 degreeC in 4 hours.

The polymerization temperature was maintained at 325 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.5 hours, and the reaction was continued for another 20 minutes. When the predetermined torque was reached, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand-like material via a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  This liquid crystal polyester (Reference Example 2) is composed of 73 mol% of p-hydroxybenzoic acid units and 27 mol% of 6-hydroxy-2-naphthoic acid units, and has a melting point of 283 ° C. Used, the melt viscosity measured at a temperature of 293 ° C. and a shear rate of 1000 / sec was 32 Pa · sec. The molecular weight was 230000.

Example 1
After vacuum drying at 160 ° C. for 12 hours using the liquid crystalline polyester of Reference Example 1, it was melt extruded with a φ15 mm single-screw extruder (heater temperature 290 to 340 ° C.) manufactured by Osaka Seiki Co., Ltd. and measured with a gear pump. However, the polymer was supplied to the spinning pack. The spinning temperature from the extruder to the spinning pack at this time was 345 ° C. In the spinning pack, the polymer is filtered using a metal nonwoven fabric filter (WLF-10 manufactured by Watanabe Yoshikazu Seisakusho Co., Ltd.), and the discharge amount is 5.0 g / min (from the die having five holes with a hole diameter of 0.13 mm and a land length of 0.26 mm). The polymer was discharged at a rate of 1.0 g / min per single hole.

  The discharged polymer was allowed to pass through a 40 mm heat retaining region, and then cooled and solidified from the outside of the yarn with an annular cooling air, and all 5 filaments were taken up by a first godet roll of 1000 m / min. The spinning draft at this time is 16. After passing this through the second godet roll at the same speed, four of the five filaments are sucked with a suction gun, and the remaining one is brought into contact with the spindle traverse type pirn winder (winding package) through the dancer arm. It was wound up in the shape of a pan using a contact roll). During the winding time of about 100 minutes, yarn breakage did not occur and the yarn making property was good.

  The fiber properties of the spun fiber before solid phase polymerization were a fineness of 10.0 dtex, a strength of 5.5 cN / dtex, an elongation of 1.1%, and an elastic modulus of 494 cN / dtex.

A winding machine (ET-68S controlled winding by Kozu Seisakusho Co., Ltd.) that unwinds fibers from the spun fiber package in the longitudinal direction (perpendicular to the fiber circulation direction) and keeps the speed constant without using a speed control roller. Machine) at 200 m / min. At this time, an aqueous solution in which 0.5% by weight of CF ₃ CF ₂ (CF ₂ CF ₂ ) ₂ CH ₂ CH ₂ OPO (ONH ₄ ) ₂ [hereinafter referred to as C8F compound] is dispersed in water during the rewinding process is used. It was made to adhere to a fiber using the oiling guide so that the adhesion weight of a compound might be 2.0 weight% with respect to a fiber. In order to improve the dispersibility of the C8F compound, polyoxyethylene alkylphenyl ether was added in the same amount as the C8F compound as a dispersibility stabilizer in the aqueous solution. Thereafter, polydimethylsiloxane (“SH200-350cs” manufactured by Toray Dow Corning Co., Ltd., viscosity 350 cSt) [hereinafter referred to as PDMS] 1.0 wt% A water-based emulsion was used so that 4.0 wt% with respect to the fiber was used. And adhered to the fiber. In any oil supply, there was no scattering or return of the oil, and the entire discharge amount of the oil supply guide adhered to the fiber. As the core material for rewinding, a stainless steel perforated bobbin wound with Kevlar felt (weight per unit: 280 g / m ² , thickness: 1.5 mm), the tension at the time of rewinding was 0.05 cN / dtex, and the winding density was 0 0.08 g / cm ³ and the winding amount was 20,000 m. Furthermore, the package shape is a taper end winding with a taper angle of 20 °, the traverse width is always oscillated by modifying the taper width adjustment mechanism, no contact roll is used, and the traverse guide and fiber contact point is 5 mm from the fiber package. did.

  Using a closed oven, the temperature was raised from room temperature to 240 ° C. in about 30 minutes, held at 240 ° C. for 3 hours, then heated to 295 ° C. at 4 ° C./hour, and further at 295 ° C. for 15 hours. Solid state polymerization was carried out under the conditions maintained. The atmosphere was supplied with dehumidified nitrogen at a flow rate of 25 NL / min, and exhausted from the exhaust port so that the interior was not pressurized.

  The solid phase polymerization package obtained in this way was attached to a feeding device that can be rotated by an inverter motor, unwound while feeding the fibers in the transverse direction (fiber circumferential direction) at 200 m / min, and wound up with a winder. The yarn could be unwound without resistance and no yarn breakage occurred. The fiber properties are as shown in Table 2. The molecular weight of the fiber after solid phase polymerization is 420,000. The measuring method is the same as that of the liquid crystal polyester polymer.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 2
Implemented except that the discharge rate in melt spinning is 1.2 g / min (0.24 g / min per single hole), and the solution to be adhered is a C8F compound 0.2 wt% solution and PDMS 0.4 wt% aqueous emulsion. A solid state polymerization package was obtained in the same manner as in Example 1.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 3
A polymer having a discharge diameter of 5.76 g / min (0.24 g / min per single hole) is discharged from a die having 24 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm. A solid phase polymerization package was obtained in the same manner as in Example 1 except that the solution was made into a filament and the adhering solution was a 1.0 wt% C8F compound solution and a 2.0 wt% PDMS aqueous emulsion.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Also, the number of defects in the package was 0 and the quality was good.

Example 4
A solid-state polymerization package is obtained in the same manner as in Example 1 except that the fluorine compound attached to the fiber is F (CF ₂ CF ₂ ) ₂ CH ₂ CH ₂ PO (ONH ₄ ) ₂ [hereinafter referred to as C6F compound]. It was.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. There was light fusion and local resistance, but there was no yarn breakage. It was possible to unravel.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 5
Using the liquid crystalline polyester of Reference Example 2, melt spinning was performed in the same manner as in Example 1 except that the spinning temperature was 315 ° C.

  This spun fiber had a fineness of 10.0 dtex, a strength of 8.1 cN / dtex, an elongation of 1.7%, and an elastic modulus of 553 cN / dtex.

  This was rolled up in the same manner as in Example 1, heated from room temperature to 240 ° C. in about 30 minutes, held at 240 ° C. for 3 hours, heated to 265 ° C. at 4 ° C./minute, and further 265 Solid phase polymerization was performed in the same manner as in Example 1 except that the conditions were maintained at 15 ° C. for 15 hours. The molecular weight of the fiber after solid phase polymerization is 650000. The measuring method is the same as that of the liquid crystal polyester polymer.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 6
In the step of attaching the fluorine compound and polysiloxane before solid-phase polymerization, a 0.1% by weight C8F compound solution was attached to the fiber using an oiling guide so as to be 0.1% by weight with respect to the fiber. Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was attached to the fibers using an oiling guide so that the weight% emulsion was 1.8% by weight.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Also, the number of defects in the package was two, and the quality was good.

Example 7
In the fluorine compound and polysiloxane adhesion step before solid-phase polymerization, a 0.1% by weight C8F compound solution was adhered to the fiber by using an oiling guide so as to be 0.1% by weight with respect to the fiber, and then PDMS 4.0. Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was attached to the fibers using an oiling guide so that the amount was 19.8% by weight based on the fibers.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Also, the number of defects in the package was 0 and the quality was good.

Example 8
In the step of attaching the fluorine compound and polysiloxane before solid-phase polymerization, a 0.5% by weight C8F compound solution was attached to the fiber using an oiling guide so as to be 0.9% by weight with respect to the fiber. Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was attached to the fiber using an oil supply guide so that the weight% aqueous emulsion would be 0.3% by weight.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 9
In the fluorine compound and polysiloxane adhesion step before solid-phase polymerization, a 1.0% by weight C8F compound solution was adhered to the fiber using an oiling guide so that the solution was 8.5% by weight, and then PDMS 0.5 Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was attached to the fiber using an oiling guide so that the amount was 2.9% by weight based on the fiber.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When the liquid crystal polyester fiber was used to evaluate the process passability, no deposits or fibrils were deposited, and the process passability (workability) was good. Further, the number of defects in the package was 1 and the quality was good.

Example 10
In the step of attaching the fluorine compound and polysiloxane before solid-phase polymerization, a 0.5% by weight solution of C8F compound is attached to the fiber using an oiling guide so that the solution becomes 0.9% by weight, and then PDMS 0.1 Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was adhered to the fiber using an oil supply guide so that the weight% aqueous emulsion was 0.2% by weight.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. As a result, it was unwound with almost no resistance and no yarn breakage occurred.

  When this liquid crystalline polyester fiber was used to evaluate process passability, deposits and fibril deposits were observed, but there was no breakage in yarn for 100 minutes. Also, the number of defects in the package was 3 and the quality was good.

Example 11
In the step of attaching the fluorine compound and polysiloxane before solid phase polymerization, a 0.2% by weight solution of C8F compound is attached to the fiber using an oiling guide so that the solution is 0.5% by weight, and then PDMS 0.2 Solid phase polymerization was carried out in the same manner as in Example 1 except that the weight% aqueous emulsion was attached to the fibers using an oiling guide so that the weight% aqueous emulsion would be 0.5% by weight.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. There was light fusion and local resistance, but there was no yarn breakage. It was possible to unravel.

  When this liquid crystalline polyester fiber was used to evaluate process passability, deposits and fibril deposits were observed, but there was no breakage in yarn for 100 minutes. Also, the number of defects in the package was 3 and the quality was good.

Comparative Example 1
Before solid-phase polymerization, the same solution as in Example 1 except that a 1.0 wt% C8F compound solution is attached to the fiber using an oiling guide so as to be 3.0 wt% with respect to the fiber, and PDMS is not attached. Solid phase polymerization package was obtained by the method.

  The solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound up with a winder. There was light fusion and local resistance, but there was no yarn breakage. It was possible to unravel.

  When this liquid crystalline polyester fiber was used to evaluate the process passability, the fiber surface was fibrillated and thread breakage occurred. Further, the number of defects in the package was 5, and the quality was poor.

Comparative Example 2
Prior to solid-state polymerization, PDMS 2.0 wt% aqueous emulsion is the same as in Example 1 except that the oil-based guide is used to attach PDMS 2.0 wt% aqueous emulsion to 5.0 wt%, and no C8F compound is attached. Solid phase polymerization package was obtained by the method.

  When the solid phase polymerization package thus obtained was unwound in the same manner as in Example 1 and wound by a winder, yarn breakage occurred, and even if the feed speed was 50 m / min, it was caused by fusion. A thread break occurred.

  This liquid crystal polyester fiber could not be evaluated for process passability.

Claims (3)

A method for producing a liquid crystal polyester fiber, comprising: attaching a fluorine compound having 40 or less carbon atoms and polysiloxane to a fiber obtained by melt spinning a liquid crystal polyester, and then performing solid phase polymerization for 5 hours or more .   2. The method for producing a liquid crystal polyester fiber according to claim 1, wherein the liquid crystal polyester fiber is a monofilament.   3. A liquid crystal polyester fiber having a strength of 10 cN / dtex or more, an elongation of 1.0% or more, and an elastic modulus of 500 cN / dtex or more obtained by the production method according to claim 1.