JP2010248681A - Liquid crystal polyester fibers and winding package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide liquid crystal polyester fibers having high tenacity, high elasticity and excellent abrasion resistance, and particularly excellent in uniformity in the longitudinal direction to improve weavability and woven fabric quality of woven fabrics. <P>SOLUTION: Provided are liquid crystal polyester fibers, which have a peak half-width of 15°C or greater at an endothermic peak (Tm1) observed by differential calorimetry under a temperature elevation rate of from 50 to 20°C/minute, a weight-average molecular weight in terms of polystyrene of between 250,000 and 2,000,000, and a variable waveform of less than 10% in terms of the half inert diagram mass waveform by a Worcester yarn irregularity tester. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal polyester fiber having high strength and high elastic modulus, excellent uniformity in the longitudinal direction of the fiber, and excellent wear resistance.

  Liquid crystalline polyester is a polymer composed of rigid molecular chains. In melt spinning, the molecular chains are highly oriented in the fiber axis direction, and further subjected to heat treatment (solid phase polymerization). It is known that the highest strength and elastic modulus can be obtained. In addition, it is also known that liquid crystal polyester has an increased molecular weight due to solid-phase polymerization and an increased melting point, thereby improving heat resistance and dimensional stability (see Non-Patent Document 1). Thus, liquid crystal polyester fibers exhibit high strength, high elastic modulus, excellent heat resistance, and thermal dimensional stability by solid phase polymerization. On the other hand, the liquid crystalline polyester fiber has a rigid molecular chain highly oriented in the fiber axis direction and produces dense crystals. Therefore, the interaction in the direction perpendicular to the fiber axis is low, and fibrils are easily generated by friction. It also has the disadvantage of being inferior in wear.

  In recent years, particularly for filters made of monofilaments and screen printing ridges, there has been a growing demand for higher weaving density (higher mesh) and larger openings (openings) to improve performance. In order to achieve this, there is a strong demand for fineness, high strength, and high elastic modulus of single fiber fineness, and liquid crystal polyester fibers have high expectations because they have high strength and high elastic modulus. On the other hand, a reduction in the defect of the opening is also required at the same time for higher performance, but the liquid crystal polyester fiber is disadvantageous in this respect because it is inferior in wear resistance. In the liquid crystal polyester fiber, the above-mentioned fibrils are caused by fusing defects in solid phase polymerization or friction in higher processing steps, so that fusing defects are reduced, that is, the strength in the longitudinal direction of the fiber, the uniformity of the fineness is improved, the fiber There is a need for improved wear resistance. In addition, deterioration of processability and high weaving in the fiber high-order processing process such as weaving is caused by fibril catching or tension fluctuation due to fibril deposition on the guide, and the strength and fineness of the fiber in the longitudinal direction are uniform. There is a need for improvement and improved wear resistance of fibers.

  For improving the abrasion resistance of the liquid crystal polyester fiber, the temperature of the endothermic peak temperature (Tm1) + 10 ° C. or higher observed when the liquid crystal polyester fiber is measured under a temperature increase condition of 50 ° C. to 20 ° C./min in differential calorimetry. The technique of heat-treating is proposed (see Patent Documents 1 and 2). This technique is excellent in terms of improving the abrasion resistance, but is insufficient in terms of uniformity in the fiber longitudinal direction. The techniques described in Patent Documents 1 and 2 are processes in which liquid crystalline polyester fibers are solid-phase polymerized in the state of fibers, then unwinding and winding them once, and high-temperature heat treatment is performed while unwinding the fibers from the wound package once again. It consists of two steps of applying. The reason why the unwinding after the solid-phase polymerization and the high-temperature heat treatment are two steps is that the unraveling after the solid-phase polymerization is difficult to make the speed constant, and is continuous with the high-temperature heat treatment that is a constant speed process. This is because it is impossible. The reason why the unwinding speed after solid-phase polymerization is not constant is that the solid-phase polymerized package is slightly fused, and if the fused part is forcibly peeled off, the fibers will become fibrillated, so we want to unwind with low tension. For this reason, it is preferable to rotate the package by positive driving and feed out the fibers. If the number of rotations is constant, the feeding speed gradually decreases as the winding amount of the package decreases. Although there is a method of controlling the rotational speed so that the feeding speed is constant, a fiber having a low elongation and a high elastic modulus, such as liquid crystal polyester, has a tension fluctuation with a speed (rotational speed) change in a short time. Because it is large, it is easy to break the thread and difficult to apply.

  The techniques of Patent Documents 1 and 2 have a problem in that the solid-phase polymerized fibers are unwound and wound up once. When winding the fiber, it is necessary to apply tension to the fiber so that it does not loosen and wind it around the package while traversing it using the yarn path guide. In particular, since the tension is increased at both ends of the traverse, the fibers are slightly fibrillated. This slight fibrillation has little effect on the fineness and strength of the fiber, but the accumulated fibrils accumulate in the traverse guide, so that the tension fluctuation increases with time, that is, the winding amount increases, and sudden tension It causes yarn breakage and severe fibrillation due to abnormalities, causing local reduction in fineness and strength. In some cases, the accumulated fibrils are wrapped around the fiber, and in this case, the fineness is locally increased. Furthermore, when high-temperature heat treatment is performed on solid-phase polymerized yarns with locally abnormal fineness, running stability deteriorates due to fibrils, tension fluctuations during high-temperature heat treatment increase, and abnormality in fineness becomes worse. It also causes fiber fusing.

  In addition, it is preferable to add an oil agent to prevent fusion in solid phase polymerization. However, since the high temperature heat treatment temperature after solid phase polymerization is higher than the solid phase polymerization temperature, the oil agent is sublimated in the high temperature heat treatment apparatus. In addition to causing the problem of tension fluctuation due to contact with the fiber that travels over time, when the deposit is caught and remains in the final product, it accumulates again on the guide on the loom, etc. There is a problem of causing defects and thread breakage. For this reason, it is preferable to wash and remove the oil agent for solid-phase polymerization at the time of unwinding after solid-phase polymerization, but since the effect of reducing the frictional resistance of the oil agent is lost by washing and removal, the running tension becomes high and fibrillation occurs. Since it becomes easy, winding of a solid phase polymerization thread | yarn will become further disadvantageous.

  As described above, in the techniques of Patent Documents 1 and 2, the problem is hardly manifested at a relatively small amount of about tens of thousands of meters, but when the amount of continuous processing increases, a local abnormality occurs in the longitudinal direction of the fiber. There is a problem of end. This is because the fiber after solid-phase polymerization is unwound and wound up once.

  In addition, in Patent Document 1, there is a description regarding “high-temperature heat treatment may be continued while unwinding the fiber from the package”, but in the unraveling, it is preferable that the solid-state polymerization package be “rotated by active driving”. It is also described. As described above, when the solid-phase polymerized package is rotated, the traveling speed of the fibers is not constant. Therefore, if the unwinding and the high-temperature heat treatment are continuously performed in such a state, the heat treatment speed is not constant, and the longitudinal direction is increased. In addition to unevenness in strength and wear resistance, the fluctuations in the unwinding tension are directly transmitted to the high-temperature heat treatment process, which causes the tension to fluctuate, resulting in yarn breakage and abnormal fineness. Further, Patent Document 1 does not describe the washing and removal of the solid phase polymerized oil, and there is no suggestion regarding the continuous treatment of the solid phase polymerized yarn from which the oil has been removed.

JP 2008-240228 A (first page) JP 2008-240230 A (first page)

Edited by Technical Information Association, “Modification of liquid crystal polymer and latest applied technology” (2006) (pages 235-256)

  An object of the present invention is to provide a liquid crystal polyester fiber having both high strength, high elastic modulus, excellent wear resistance, and particularly excellent longitudinal uniformity.

  The present inventors examined processes such as melt spinning that can achieve high strength, high elastic modulus, and excellent wear resistance, rewinding before solid phase polymerization, solid phase polymerization, unwinding after solid phase polymerization, and high temperature heat treatment. As a result, the cause of deterioration in uniformity in the longitudinal direction of the fiber lies in winding after unwinding after solid-phase polymerization, and it was found that uniformity could be improved by not performing this winding, leading to the solution of the problems described above. .

  That is, in the differential calorimetry, the peak half-value width at the endothermic peak (Tm1) observed when the temperature is measured at 50 ° C. to 20 ° C./min in the differential calorimetry is 15 ° C. or more, and the weight average in terms of polystyrene A liquid crystal polyester fiber having a molecular weight of 255,000 or more and 200,000 or less and having a fluctuation waveform of less than 10% in a half inert diagram mass waveform in a Worcester yarn unevenness tester.

  Since the liquid crystalline polyester fiber of the present invention has high strength, high elastic modulus and excellent wear resistance, it is excellent in process passability in high-order processing of fibers such as weaving and knitting, and the weaving density is increased. In addition to improving the weaving property, the fabric quality can be improved because of excellent uniformity in the longitudinal direction. Especially for filters and screens that require high mesh fabrics, weaving density is increased (higher mesh), opening area is increased, opening defects are reduced to improve performance. Improved weaving can be achieved.

  Hereinafter, the liquid crystal polyester fiber of the present invention will be described in detail.

  The liquid crystal polyester used in the present invention is a polyester capable of forming an anisotropic melt phase (liquid crystallinity) upon melting. This characteristic can be confirmed, for example, by placing a sample made of liquid crystal polyester on a hot stage, heating and heating in a nitrogen atmosphere, and observing the transmitted light of the sample under polarized light.

  Examples of the liquid crystal polyester used in the present invention include a. A polymer of aromatic oxycarboxylic acid, b. Polymer of aromatic dicarboxylic acid and aromatic diol, aliphatic diol, c. Examples include a copolymer of a and b, and a wholly aromatic polyester that does not use an aliphatic diol is preferable for high strength, high elastic modulus, and high heat resistance. Here, examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid, hydroxynaphthoic acid and the like, and alkyl, alkoxy and halogen substituted products of the above aromatic oxycarboxylic acid. Examples of the aromatic dicarboxylic acid 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 aromatic dicarboxylic acid. Examples include halogen substitution products. Furthermore, examples of the aromatic diol include hydroquinone, resorcin, dioxydiphenyl, naphthalene diol, and the like, and alkyl, alkoxy, and halogen substituted products of the above aromatic diol. Examples of the aliphatic diol include ethylene glycol, propylene glycol, Examples include butanediol and neopentyl glycol.

  As the liquid crystalline polyester used in the present invention, a p-hydroxybenzoic acid component, a 4,4′-dihydroxybiphenyl component, a hydroquinone component, a terephthalic acid component and / or an isophthalic acid component are copolymerized, and p-hydroxybenzoic acid. A copolymer of a component and a 6-hydroxy 2-naphthoic acid component, a copolymer of a p-hydroxybenzoic acid component, a 6-hydroxy 2-naphthoic acid component, a hydroquinone component, and a terephthalic acid component, etc. It is excellent in spinnability, can achieve high strength and high elastic modulus, and wear resistance is improved by performing high-temperature heat treatment after solid phase polymerization.

  In the present invention, a liquid crystal polyester composed of the following structural units (I), (II), (III), (IV), and (V) is particularly preferable. In the present invention, the structural unit refers to a unit that can constitute a repeating structure in the main chain of the polymer.

  This combination results in the molecular chain having the proper crystallinity and non-linearity, ie, a melt-spinnable melting point. Therefore, the fiber has good spinning performance at the spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, and a uniform fiber can be obtained in the longitudinal direction. Can be increased.

  Furthermore, it is important to combine components composed of diols that are not bulky and have high linearity such as structural units (II) and (III). By combining these components, the molecular chains in the fibers are ordered and disordered. In addition to having a small structure, the crystallinity is not excessively increased and the interaction in the direction perpendicular to the fiber axis can be maintained. In addition to obtaining high strength and elastic modulus, high-temperature heat treatment is performed after solid-phase polymerization, so that particularly excellent wear resistance can be obtained.

  Further, the structural unit (I) is preferably 40 to 85 mol%, more preferably 65 to 80 mol%, still more preferably 68 to 85 mol% with respect to the total of the structural units (I), (II) and (III). 75 mol%. By setting it as such a range, crystallinity can be made into an appropriate range, high intensity | strength and an elasticity modulus are obtained, and melting | fusing point also becomes the range which can be melt-spun.

  The structural unit (II) is preferably 60 to 90 mol%, more preferably 60 to 80 mol%, still more preferably 65 to 75 mol%, based on the total of the structural units (II) and (III). By setting it as such a range, since crystallinity does not become high excessively and the interaction of a fiber axis perpendicular | vertical direction can be maintained, wear resistance can be improved by performing high temperature heat processing after solid-phase polymerization.

  The structural unit (IV) is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, still more preferably 60 to 85 mol%, based on the total of the structural units (IV) and (V). By setting such a range, the melting point of the polymer becomes an appropriate range, and it has good spinnability at a spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, so that a uniform fiber can be obtained in the longitudinal direction. Since the linearity of the polymer is moderately disturbed, the fibril structure is easily disturbed by the high-temperature heat treatment after the solid phase polymerization, and the interaction in the direction perpendicular to the fiber axis is increased, thereby improving the wear resistance.

The preferred range of each structural unit of the liquid crystalline polyester used in the present invention is as follows. The liquid crystal polyester fiber of the present invention can be suitably obtained by adjusting the composition so as to satisfy the above conditions within this range.
Structural unit (I) 45-65 mol%
Structural unit (II) 12-18 mol%
Structural unit (III) 3 to 10 mol%
Structural unit (IV) 5-20 mol%
Structural unit (V) 2-15 mol%
In addition to the above structural units, the liquid crystalline polyester used in the present invention includes aromatic dicarboxylic acids such as 3,3′-diphenyldicarboxylic acid and 2,2′-diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Aliphatic dicarboxylic acids such as hexahydroterephthalic acid (1,4-cyclohexanedicarboxylic acid), chlorohydroquinone, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfide, 4 An aromatic diol such as 4,4'-dihydroxybenzophenone and p-aminophenol may be copolymerized within a range of about 5 mol% or less without impairing the effects of the present invention.

  In addition, within a range of about 5% by weight or less that does not impair the effects of the present invention, a vinyl polymer such as polyester, polyolefin or polystyrene, polycarbonate, polyamide, polyimide, polyphenylene sulfide, polyphenylene oxide, polysulfone, aromatic polyketone, aliphatic polyketone. , Semi-aromatic polyester amide, polyether ether ketone, fluororesin and other polymers may be added. Polyphenylene sulfide, polyether ether ketone, nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T, polyethylene terephthalate, Polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexanedimethanol terephthalate, polyester 99M, etc. are suitable It is mentioned as examples. When these polymers are added, the melting point thereof is preferably within the melting point ± 30 ° C. of the liquid crystalline polyester so as not to impair the spinning property.

  Furthermore, within the range not impairing the effects of the present invention, various metal oxides, kaolin, silica and other inorganic substances, colorants, matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents In addition, various additives such as a fluorescent brightening agent, a terminal group blocking agent, and a compatibilizing agent may be contained in a small amount.

  The weight average molecular weight (hereinafter referred to as molecular weight) in terms of polystyrene of the fiber of the present invention is from 255,000 to 200,000. By having a high molecular weight of 255,000 or more, it has high strength, elastic modulus, and elongation. The higher the molecular weight, the higher the strength, elastic modulus, and elongation, and therefore it is preferably 30 million or more, more preferably 350,000 or more. 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 200,000. The molecular weight referred to in the present invention is a value determined by the method described in the examples.

  The fiber of the present invention has a peak half-value width of 15 ° C. or more in an endothermic peak (Tm1) observed when measured under a temperature rising condition of 50 ° C. to 20 ° C./min in differential calorimetry. Tm1 in this measurement method represents the melting point of the fiber, and it can be said that the peak shape has a higher crystallinity as the area is larger, that is, as the heat of fusion ΔHm1 is larger, and as the half-value width is narrower, the completeness of the crystal is higher. Liquid crystal polyester is subjected to solid phase polymerization after spinning, Tm1 increases, ΔHm1 increases, half width decreases, and the crystallinity and crystal integrity increase, so that the strength, elongation, and elastic modulus of the fiber are increased. Increases heat resistance. On the other hand, the wear resistance deteriorates, but this is thought to be due to the fact that the structural difference between the crystal part and the amorphous part becomes remarkable due to the increase in crystal perfection, so that the interface breaks down. Therefore, in the fiber of the present invention, while maintaining the high Tm1, high strength, elongation, and elastic modulus, which are the characteristics of the solid-phase polymerized fiber, the peak half-value width is 15 ° C. like liquid crystal polyester fiber not solid-phase polymerized. By increasing to the above values, the crystallinity is lowered, the crystal / amorphous structural difference that is the starting point of fracture is reduced, the fibril structure is disturbed, and the entire fiber is softened to increase the wear resistance. It can be done. The peak half width at Tm1 is preferably 20 ° C. or higher because higher wear resistance is higher. The upper limit is not particularly limited, but the upper limit that can be industrially reached is about 80 ° C.

  In the liquid crystal polyester fiber of the present invention, there is one endothermic peak, but two or more peaks may be observed depending on the fiber structure, such as when solid phase polymerization is insufficient. In this case, the peak half-value width is the sum of the half-value widths of the respective peaks.

  Further, it is preferable that the fiber of the present invention does not substantially exhibit an exothermic peak when measured under a temperature increase condition of 50 ° C. to 20 ° C./min in differential calorimetry. The fact that a substantially exothermic peak is not observed means that a peak with a calorific value of 3.0 J / g or more, preferably 1.0 J / g or more, more preferably 0.5 J / g or more is not observed, Small or gradual fluctuations in the baseline are not considered peaks. The exothermic peak is observed when the crystalline polymer is contained in the fiber in an amorphous state, and the absence of the exothermic peak indicates that the fiber is substantially a liquid crystal polyester single component. When the fiber is substantially a single component of liquid crystal polyester, the characteristics of the liquid crystal polyester can be sufficiently exhibited, and the strength, elastic modulus, heat resistance, and thermal dimensional stability are excellent.

  The melting point (Tm1) of the fiber of the present invention is preferably 290 ° C. or higher, more preferably 300 ° C. or higher, and further preferably 310 ° C. or higher. By having such a high melting point, the heat resistance as a fiber is excellent. In order to achieve a high melting point of the fiber, there are methods such as spinning a liquid crystal polyester polymer having a high melting point, in order to obtain a fiber having particularly high strength and elastic modulus and excellent longitudinal uniformity. For this, it is preferable to solid-phase polymerize melt-spun fibers. In addition, although the upper limit of melting | fusing point is not specifically limited, As an upper limit which can be achieved by this invention, it is about 400 degreeC.

  Further, the value of heat of fusion ΔHm1 varies depending on the composition of the structural unit of the liquid crystal polyester, but is preferably 6.0 J / g or less. ΔHm1 is reduced to 6.0 J / g or less, so that the degree of crystallinity is lowered, the fibril structure is disturbed, the entire fiber is softened, and the crystal / amorphous structural difference that is the starting point of fracture is reduced. Abrasion resistance is improved. As ΔHm1 is lower, the wear resistance is improved, so 5.0 J / g or less is more preferable. The lower limit of ΔHm1 is not particularly limited, but 0.5 J / g or more is preferable in order to obtain high strength and elastic modulus.

  It is surprising that ΔHm1 is as low as 6.0 J / g or less even though the molecular weight is as high as 255,000 or more. A liquid crystal polyester having a molecular weight of 255,000 or more has a viscosity that is extremely high even when the melting point is exceeded and does not flow and is difficult to melt-spin. Such a high-molecular-weight liquid crystal polyester fiber melts and spins a low-molecular weight liquid crystal polyester, This fiber is obtained by solid phase polymerization. When the liquid crystalline polyester fiber is solid-phase polymerized, the molecular weight is increased and the strength, elongation, elastic modulus, and heat resistance are improved. At the same time, the crystallinity is increased and ΔHm1 is increased. When the degree of crystallinity increases, the strength, elongation, elastic modulus, and heat resistance are further improved, but the structural difference between the crystal part and the amorphous part becomes remarkable, the interface is easily broken, and the wear resistance is lowered. . On the other hand, in the present invention, the high molecular weight, which is one of the characteristics of the solid phase polymerized fiber, maintains high strength, elongation, elastic modulus and heat resistance, and liquid crystal polyester fiber not solid phase polymerized. Wear resistance can be improved by having such a low crystallinity, that is, a low ΔHm1. In the present invention, there is a technical advance in that the abrasion resistance is improved by reducing the structural change, that is, the degree of crystallinity, of the fiber consisting essentially of liquid crystalline polyester.

  If such a fiber structure can be achieved, its production method is not particularly limited, but in order to make the structure uniform and improve the productivity, while continuously running solid-state polymerized liquid crystal polyester fibers as described later, It is preferable to heat-treat the liquid crystalline polyester fiber at Tm1 + 10 ° C. or higher.

  Although Tc of the fiber of the present invention varies depending on the composition, it is preferably 250 ° C. or higher and 350 ° C. or lower in order to improve heat resistance. If ΔHc is too low, the crystallinity will decrease and the strength and elastic modulus will decrease. If it is excessively large, the crystallinity will increase excessively and it will be difficult to improve the wear resistance. / G or less is preferable. In the liquid crystalline polyester fiber of the present invention, there is one exothermic peak at the time of cooling under the measurement conditions described above, but two or more peaks may be observed depending on the structural change due to heat treatment after solid phase polymerization. is there. In this case, ΔHc is the sum of ΔHc of each peak.

  Moreover, although Tm2 of the fiber of this invention changes with a composition, in order to improve heat resistance, 300 degreeC or more is preferable. The upper limit of Tm2 is not particularly limited, but the upper limit that can be reached in the present invention is about 400 ° C. If ΔHm2 is excessively large, the crystallinity of the polymer itself becomes high and it is difficult to improve the wear resistance, so 5.0 J / g or less is preferable, and 2.0 J / g or less is more preferable. In the liquid crystalline polyester fiber of the present invention, there is one endothermic peak at the time of reheating after cooling under the above-described measurement conditions, but two or more peaks may be observed. In this case, ΔHm2 is the sum of ΔHm2 of each peak.

  The fiber of the present invention has a fluctuation waveform of less than 10% in a half inert diagram mass waveform (hereinafter referred to as U% H) in a Worcester yarn unevenness testing machine. The fluctuation waveform in U% H referred to in the present invention is a value obtained by the method described in the examples. A fiber diameter abnormality of a wavelength of about 1 m or more is detected by U% H. Such an abnormality is observed, for example, when the accumulated fibrils are mixed with the fiber, the fiber diameter is increased abnormally (many Accumulated fibrils do not mix all in an instant and are divided into several stages, resulting in a long-period abnormality). Abnormal fiber diameter when the fibril adheres to the roll before high-temperature heat treatment and the running stability deteriorates (the length of the heater) An unusually long cycle). The fluctuation waveform of the fiber of the present invention is less than 10%, which means that there is no abnormality in a long period due to fiber shaving or fibrillation, and the fiber diameter is uniform in the longitudinal direction. In this way, the fiber diameter is uniform in the longitudinal direction, so that the process passability and weaving in high-order processes such as weaving are good, and the fiber opening (opening) is uniform even when made into a woven fabric. Good quality. The smaller the fluctuation waveform is, the higher the uniformity in the fiber longitudinal direction is, so that it is more preferably less than 8%.

  The fiber of the present invention preferably has a variation value in the outer diameter measurement of less than 30%. The fluctuation value in the outer diameter measurement referred to in the present invention is a value obtained by the method described in the examples. Fiber diameter abnormalities with a wavelength of several centimeters are detected by the outer diameter measurement. Such abnormalities are observed when the fiber diameter is lowered due to local shaving of the fiber, or the fiber diameter is increased due to fibril mixing. Abnormality (when mixed before it is largely deposited, it becomes an abnormality of a small cycle). The fluctuation value in the outer diameter measurement of less than 30% indicates that the fiber diameter is uniform in the longitudinal direction even in a relatively short period, and therefore the process passability and weaving property in higher-order processes such as weaving are good. It becomes good and the textile quality becomes good. The smaller the variation value in the outer diameter measurement, the higher the uniformity in the fiber longitudinal direction. Therefore, the variation value is more preferably less than 20%, and even more preferably less than 15%.

  Uniformity of the fiber diameter in the longitudinal direction of the fiber is an important item particularly in printing screen wrinkles made of monofilaments and filter mesh fabrics. When such a woven fabric is continuously produced several tens of meters or more, several hundreds of thousands of wefts are required. However, as described in the prior art, in Patent Documents 1 and 2, if the yarn length becomes long, solid-state polymerized yarns Due to the winding of the fiber, the uniformity of the fiber diameter deteriorates. On the other hand, in the present invention, a fiber having excellent uniformity can be obtained by eliminating the winding of solid phase polymerization itself, and the quality of a continuous fabric of several tens of meters can be improved. At this time, since there is no abnormality having a long period, particularly represented by U% H, continuous abnormality does not occur in the fabric, and the loss of the product can be minimized.

  The strength of the fiber of the present invention is preferably 12.0 cN / dtex or more, more preferably 14.0 cN / dtex or more, and further preferably 15.0 cN / dtex or more in order to increase the strength of the fabric. 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. The strength referred to in the present invention refers to the tensile strength described in JIS L1013: 1999.

  The elastic modulus is preferably 500 cN / dtex or more, more preferably 600 cN / dtex or more, and further preferably 700 cN / dtex or more in order to increase the elastic modulus of the fabric. 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. The elastic modulus referred to in the present invention refers to the initial tensile resistance described in JIS L1013: 1999.

  High strength and elastic modulus make it suitable for applications such as ropes, tension members and other reinforcing fibers, printing screens, filter meshes, etc. And thinning can be achieved, and yarn breakage in higher processing steps such as weaving can be suppressed. In the fiber of the present invention, high strength and elastic modulus can be obtained when the molecular weight is 255,000 or more.

  The single fiber fineness of the 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 molecular weight is easily increased when solid-phase polymerization is performed in a fiber state, and the strength, elongation, and elastic modulus are improved. In addition to having the properties of improving the flexibility of the fiber and improving the processability of the fiber, increasing the surface area and improving the adhesion with chemicals such as adhesives, in addition to the case of a cocoon made of monofilament The thickness can be reduced, the woven density can be increased, and the opening (area of the opening) can be widened. The single fiber fineness is more preferably 10.0 dtex or less, and even more preferably 7.0 dtex or less. The lower limit of the single fiber fineness is not particularly limited, but the lower limit that can be achieved in the present invention is about 1.0 dtex.

  The fineness variation rate of the fiber of the present invention is preferably 30% or less, more preferably 20% or less, and still more preferably 10% or less. The fineness fluctuation rate referred to in the present invention refers to a value measured by the method described in the examples. When the fineness variation rate is 30% or less, the uniformity of the fineness in the longitudinal direction is high, and the variation in fiber strength (the product of strength and fineness) is also small. Since the diameter variation is small, the uniformity of the opening (area of the opening) when it is made can be improved, and the performance of the bag can be improved.

  The strength variation rate of the fiber of the present invention is preferably 20% or less, and more preferably 15% or less. The strength referred to in the present invention refers to the strength at the time of cutting in the measurement of tensile strength described in JIS L1013: 1999, and the strength fluctuation rate refers to a value measured by the method described in the examples. When the strength fluctuation rate is 20% or less, the uniformity of strength in the longitudinal direction is increased, and defects in the fabric are reduced. Further, yarn breakage in a high-order processing step caused by a low strength portion can be suppressed.

  The elongation of the fiber of the present invention is preferably 1.0% or more, and more preferably 2.0% or more. When the elongation is 1.0% or more, the impact absorbability of the fibers is increased, the process passability and the handleability in the high-order processing step are excellent, and the impact absorbability is increased, so that the wear resistance is also increased. The upper limit of elongation is not particularly limited, but the upper limit that can be achieved in the present invention is about 10.0%. In the fiber of the present invention, high elongation can be obtained when the molecular weight is 255,000 or more.

  The compression elastic modulus (hereinafter referred to as compression elastic modulus) in the direction perpendicular to the fiber axis of the fiber of the present invention is preferably 0.50 GPa or less. The liquid crystalline polyester fiber of the present invention has high strength and elastic modulus in the tensile direction, but its compressive modulus is low, so that the contact area when the fiber is pressed against a guide or ridge by a high-order processing step or a loom The effect of spreading the load and dispersing the load appears. This effect reduces the pressing stress on the fiber and improves the wear resistance. The lower limit of the compressive elastic modulus is not particularly limited, but if it is 0.10 GPa or more, the amount of the fiber is crushed and deformed is small, and when used for printing screen wrinkles, the wrinkle performance can be maintained at a high level. Will not be damaged. In addition, the compression elastic modulus said by this invention points out the value calculated | required by the method of an Example description.

  The birefringence (Δn) of the fiber of the present invention is preferably from 0.250 to 0.450. If Δn is within this range, the molecular orientation in the fiber axis direction is sufficiently high, and high strength and elastic modulus can be obtained.

  In the fiber of the present invention, the peak half-value width (Δ2θ) observed at 2θ = 18 to 22 ° in the equator direction with respect to the fiber axis in wide-angle X-ray diffraction is preferably 1.8 ° or more. More preferably, it is more than or equal to °, and more preferably is more than 2.2 °. In general, in crystalline polymers, Δ2θ also increases as the crystal size decreases. However, in liquid crystal polyester, it is considered that Δ2θ increases when the contribution of disturbance of stacking is large because diffraction is given to stacking of the phenylene ring. In the liquid crystal polyester, the stacking structure is stabilized and crystallized with solid phase polymerization, so that Δ2θ decreases. When Δ2θ is as large as 1.8 ° or more, the crystallinity is lowered, the entire fiber is softened, and the crystal / amorphous structural difference that is the starting point of fracture is reduced, so that the wear resistance is improved. The upper limit of Δ2θ is not particularly limited, but the upper limit that can be achieved by the present invention is about 4.0 °. In the present invention, Δ2θ refers to a value obtained by the method described in the examples.

  The fiber obtained in the present invention is preferably attached with an oil for improving wear resistance by improving surface smoothness, improving process passability, etc., and the amount of oil attached is 0.01% by weight or more with respect to the fiber weight. Is preferred. In addition, the oil adhesion amount said by this invention refers to the value calculated | required by the method of an Example description. Since the effect increases as the amount of oil increases, 0.05% by weight or more is more preferable. However, if too much oil is present, the adhesive strength between fibers will increase, running tension will become unstable, oil will accumulate on the guide and the process will deteriorate, and sometimes it will be mixed into the product and cause defects. 2.0% by weight or less is preferable, and 1.0% by weight or less is more preferable.

  The amount of oil adhering to the surface of the liquid crystal polyester fiber becomes a factor in generating scum on the guide part in warping and weaving that is a processing process, as well as yarn due to the occurrence of scum in the process of manufacturing liquid crystal polyester fiber From the viewpoint of suppressing the cutting and improving the process stability, it is a more preferable embodiment if it is less than 0.5% by weight. When the oil adhesion amount is less than 0.5% by weight, the occurrence of scum is extremely suppressed in a tension applying device suitably used for unwinding the obtained liquid crystal polyester fiber. For example, the scum generated by the tension applying device or the like is deposited on the portion of the scraping body, which is a tension applying mechanism, and the friction resistance of the scraping body is changed, and the position of the traveling fiber on the scraping body is changed. Therefore, it becomes a factor of tension fluctuation. If the tension fluctuates, in the subsequent process, the liquid crystal polyester fiber will be stretched and loosened, which will cause the product quality in the intermediate process and final process to deteriorate, and in the worst case. There is a possibility that the process is stopped and a large loss occurs. From this, it is a more preferable embodiment that the oil adhesion amount is less than 0.3% by weight.

  The unwinding tension fluctuation rate of the liquid crystal polyester fiber of the present invention is preferably less than 30%. The unraveling tension fluctuation rate is a parameter measured by the method described in the examples. Fluctuation in the unwinding tension induces loosening of the liquid crystal polyester fiber in the warp process and weft-in process during weaving, especially when manufacturing the fabric, which causes the fabric to be loosened and pulled. . Since such slack and pulling deteriorate the quality of the fabric, it is a preferable aspect not to generate it, that is, to suppress fluctuations in the unwinding tension as much as possible. Variations in unwinding tension are caused by various factors. One of many factors is that oil remaining on the fiber surface, for example, accumulates on the yarn path guide, causing fluctuations in unwinding tension. Sometimes. Therefore, from the viewpoint of reducing the unwinding tension fluctuation rate and stabilizing the running yarn, it is a more preferable aspect that the oil adhesion amount is not substantially adhered to the surface of the liquid crystal polyester fiber.

  As described above, the unwinding tension fluctuation rate is preferably less than 30%, more preferably less than 20%, and most preferably less than 15% from the viewpoint of improving the textile quality.

  The kind of oil agent to be attached is not particularly limited as long as it is generally used for fibers. However, liquid crystal polyester fibers have both effects of preventing fusion in solid phase polymerization and improving surface smoothness. It is preferable to use at least a polysiloxane compound having a combination, and in particular, a polysiloxane compound that is liquid at room temperature (so-called silicone oil) that can be easily applied to fibers, especially a polydimethylsiloxane compound that is suitable for water emulsification and has a low environmental impact. It is particularly preferred to include a compound. In the present invention, it is determined by the method described in the examples that the adhered oil contains a polysiloxane compound.

  The abrasion resistance C of the fiber of the present invention is preferably 20 seconds or more, more preferably 50 seconds or more, further preferably 60 seconds or more, and particularly preferably 70 seconds or more. The abrasion resistance C referred to in the present invention refers to a value measured by the method described in the examples. Abrasion resistance C of 20 seconds or more can prevent fibrillation of liquid crystalline polyester fiber in the high-order processing step, deterioration of process passability and weaving property due to fibril deposition, and opening due to weaving of accumulated fibrils In addition to suppressing clogging, cleaning and replacement cycles can be lengthened because fibril accumulation on guides is reduced.

  The number of filaments of the fiber of the present invention is preferably 50 or less, more preferably 20 or less, in order to make the fiber product thinner and lighter. In particular, since the monofilament having 1 filament is a field in which fineness, high strength, high elastic modulus, and uniformity of single fiber fineness are strongly desired, the fiber of the present invention can be particularly preferably used.

  The yarn length of the fiber of the present invention is preferably 150,000 m or more. The long yarn length allows the weaving length to be increased when the weft of the woven fabric is used, and the volume during transportation of the product can be reduced. Since this effect is enhanced as the yarn length is longer, the yarn length is more preferably 200,000 m or more. In particular, the liquid crystal polyester fiber having an oil adhesion rate of less than 0.5% by weight preferably has a fiber length of 200,000 m or more in the winding package.

  Conventionally, it was difficult to wind up the liquid crystal polyester fiber continuously for a long time because the oil adhesion rate was too high and scum was deposited on the guide portion or the like in the manufacturing process of the liquid crystal polyester fiber. Since the liquid crystal polyester fiber having an oil adhesion rate of less than 0.5% by weight obtained by the preferred production method described in the present invention can suppress scum accumulation during the production process, it is stably stabilized at 200,000 m. Since the above winding package can be obtained, it is a preferable aspect.

  Further, in the process of producing a final product typified by materials such as woven fabrics, knitted fabrics, and ropes, it can be produced without stopping the machine for a long time. Therefore, the fiber length of the winding package is preferably 200,000 m or more, and 30 More preferably, it is 10,000 m or more. Although the upper limit is not particularly defined, a fiber length of 4 million m and a package weight of about 20 kg are sufficient from the viewpoint of package weight and handling.

  Since the fiber of the present invention has a long yarn length, it is preferable to wind the fiber around a core material to form a package. Especially in the case of a monofilament as a package form, the end face is likely to collapse, so that the end face is preferably tapered, and more preferably tapered end cheese winding or pirn winding. When the taper angle of the end face is excessively large, the end face collapses, so that it is preferably 70 ° or less, and more preferably 60 ° or less. Further, when the taper angle is small, the amount of winding cannot be increased, so that it is preferably 30 ° or more, and more preferably 40 ° or more. The taper angle referred to in the present invention is defined by the following equation.

  Hereafter, the manufacture example of the liquid crystalline polyester fiber of this invention is demonstrated in detail.

  The method for producing the liquid crystal polyester used in the present invention can be produced according to a known production method. For example, the following production methods are preferred.

  (1) Deacetic acid from acetoxycarboxylic acid such as p-acetoxybenzoic acid and diacetylated compounds of aromatic dihydroxy compounds such as 4,4′-diacetoxybiphenyl and diacetoxybenzene and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid A method for producing a liquid crystalline polyester by a condensation polymerization reaction.

  (2) Hydroxycarboxylic acid such as p-hydroxybenzoic acid and aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl and hydroquinone and aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid are reacted with acetic anhydride to produce phenol. A method for producing a liquid crystalline polyester by deacetic acid polycondensation reaction after acylating a functional hydroxyl group.

  (3) Dephenolization from phenyl esters of hydroxycarboxylic acids such as p-hydroxybenzoic acid and aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl and hydroquinone and diphenyl esters of aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid A method for producing a liquid crystalline polyester by a polycondensation reaction.

  (4) A predetermined amount of diphenyl carbonate is reacted with a hydroxycarboxylic acid such as p-hydroxybenzoic acid and an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid to form a diphenyl ester, and then 4,4′-dihydroxybiphenyl. A method for producing a liquid crystalline polyester by dephenol polycondensation reaction by adding an aromatic dihydroxy compound such as hydroquinone.

  In particular, hydroxycarboxylic acids such as p-hydroxybenzoic acid, aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl and hydroquinone, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid are reacted with acetic anhydride to produce phenolic hydroxyl groups. A method of producing a liquid crystalline polyester by acylating and then deaceticating polycondensation reaction is preferable. Further, the total amount of aromatic dihydroxy compounds such as 4,4'-dihydroxybiphenyl and hydroquinone and the total amount of aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid are preferably substantially equimolar. The amount of acetic anhydride used is preferably 1.12 equivalents or less, more preferably 1.10 equivalents or less of the total of the phenolic hydroxyl groups of p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl and hydroquinone. The lower limit is preferably 1.00 equivalent or more.

  When the liquid crystalline polyester used in the present invention is produced by a deacetic acid polycondensation reaction, a melt polymerization method in which the polycondensation reaction is completed by reacting under reduced pressure at a temperature at which the liquid crystalline polyester melts can produce a uniform polymer, It is preferable because a polymer with a smaller amount of generation and excellent in yarn-making property can be obtained. For example, a predetermined amount of a hydroxycarboxylic acid such as p-hydroxybenzoic acid and an aromatic dihydroxy compound such as 4,4′-dihydroxybiphenyl and hydroquinone, an aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid, and an acetic anhydride stirring blade, Charged into a reaction vessel equipped with a distillation pipe and provided with a discharge port at the bottom, heated under stirring in a nitrogen gas atmosphere to acetylate the hydroxyl group, then raised to the melting temperature of the liquid crystalline resin, and reduced pressure A method of completing the reaction by polycondensation is mentioned. The conditions for acetylation are usually in the range of 140 to 180 ° C. for 1 to 6 hours. The polycondensation temperature is a melting temperature of the liquid crystal polyester, for example, in the range of 250 to 350 ° C., and preferably a melting point of the liquid crystal polyester polymer + 10 ° C. or higher. The degree of pressure reduction during polycondensation is usually 665 Pa or less.

  The obtained polymer can be pressurized in the reaction vessel to, for example, about 0.1 ± 0.05 MPa at a temperature at which it melts and discharged in a strand form from the discharge port provided at the lower portion of the reaction vessel.

  When producing the liquid crystalline polyester used in the present invention, the polycondensation reaction can be completed by a solid phase polymerization method. For example, the liquid crystal polyester polymer or oligomer is pulverized by a pulverizer, and the melting point (Tm) -5 ° C. to the melting point (Tm) −50 ° C. (for example, 200 to 300 ° C.) of the liquid crystal polyester under a nitrogen stream or reduced pressure. A method of heating for 1 to 50 hours, polycondensing to a desired degree of polymerization, and completing the reaction can be mentioned.

  However, in spinning, if the liquid crystalline resin produced by the solid phase polymerization method is used as it is, the highly crystallized portion generated by the solid phase polymerization remains unmelted, which causes an increase in spinning pack pressure and foreign matter in the yarn. Since there is a possibility, it is preferable that the highly crystallized portion is completely melted by kneading (repletizing) once with a twin screw extruder or the like.

  The polycondensation reaction of the liquid crystal polyester proceeds even without catalyst, but metal compounds such as stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, and magnesium metal can also be used.

  The melting point of the liquid crystalline polyester polymer used in the present invention is preferably 200 to 380 ° C. in order to widen the temperature range in which melt spinning is possible, and more preferably 250 to 360 ° C. in order to improve the spinnability. In addition, melting | fusing point of a liquid crystalline polyester polymer points out the value measured by the method of an Example description.

  The melt viscosity of the liquid crystalline polyester polymer used in the present invention is 0.5 to 200 Pa · s, and 10 to 50 Pa · s is more preferable in order to obtain high spinnability. The melt viscosity is a value measured with a Koka flow tester under the condition of melting point (Tm) + 10 ° C. and shear rate of 1,000 (1 / s).

  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. By setting the molecular weight to 30,000 or more, it has an appropriate viscosity at the spinning temperature and can improve the spinning property. The higher the molecular weight, the higher the strength, elongation and elastic modulus of the resulting fiber, but if the molecular weight is too high, the viscosity will be high and the fluidity will be poor, and eventually it will not flow, so the molecular weight is preferably less than 25 million, More preferably less than 20 million.

  The liquid crystalline polyester used in the present invention is preferably dried before being subjected to melt spinning in order to suppress foaming due to water mixing and to improve the yarn-making property. Moreover, since the monomer which remain | survives in liquid crystalline polyester can also be removed by performing vacuum drying, a yarn-making property can be improved further and it is more preferable. The drying temperature is usually 100 to 200 ° C., and vacuum drying is performed for 8 to 24 hours.

  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 through 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 less than the melting point of the liquid crystal polyester, and more preferably not less than the melting point of the liquid crystal polyester + 10 ° C. in order to improve fluidity. However, if the spinning temperature is excessively high, the viscosity of the liquid crystal polyester increases, leading to deterioration of fluidity and yarn-making property. Therefore, the temperature is preferably 500 ° C. or less, and more preferably 400 ° C. or less. 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 discharging, reducing the diameter of the die hole and increasing the land length (the length of the straight pipe portion that is the same as the diameter of the die hole) are important in terms of improving the yarn production and improving the uniformity of the fineness. . However, if the hole diameter is excessively small, clogging of the hole is likely to occur, and the diameter is preferably 0.03 mm or more and 0.30 mm or less, and more preferably 0.08 mm or more and 0.20 mm or less. If the land length is excessively long, the pressure loss increases. Therefore, the L / D defined by the quotient obtained by dividing the land length by the hole diameter is preferably 0.5 or more and 3.0 or less, more preferably 0.8 or more and 2.5 or less. preferable.

  In order to maintain uniformity, the number of holes in one die is preferably 50 holes or less, and 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 in terms of not increasing pressure loss. In order to suppress abnormal retention, it is preferable that the connecting portion between the introduction hole and the base hole is tapered.

  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, the atmospheric temperature can be increased by using a heating means, and the temperature range is preferably 100 ° C. or higher and 500 ° C. or lower, and 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 an air flow that is jetted in parallel or in an annular shape from the viewpoint of reducing the environmental load.

  The take-up speed is preferably 50 m / min or more, more preferably 500 m / min or more in order to reduce productivity and single yarn fineness. The liquid crystalline polyester mentioned as a preferred example in the present invention has a suitable spinnability at the spinning temperature, so that the take-up speed can be increased, and the upper limit is not particularly limited, but 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, and more preferably 10 or more and 100 or less from the viewpoint of improving the spinning property and improving the uniformity of the fineness.

  In melt spinning, it is preferable to add an oil agent between the cooling and solidification of the polymer and the winding to improve the handleability of the fiber. As the oil agent, known ones can be used, but a polyether compound is used in terms of improving the unwinding property when unwinding the fiber (hereinafter referred to as the spinning yarn) obtained by melt spinning in the rewinding before solid phase polymerization. It is preferable to use an aqueous emulsion of a smoothing agent mainly composed of lauryl alcohol and an emulsifier mainly composed of lauryl alcohol.

  Winding can be carried out using a known winding machine to form a package such as pirn, cheese, corn, etc. However, wrapping with a roller that does not contact the surface of the package during winding does not give the fiber a frictional force. It is preferable in that it is not fibrillated.

  Next, in order to obtain a liquid crystal polyester fiber having a molecular weight of 255,000 or more and 200,000 or less of the present invention, the spinning yarn is subjected to solid phase polymerization. By performing solid phase polymerization, the molecular weight is increased, thereby increasing strength, elastic modulus, and elongation. Solid-phase polymerization can be processed in the form of a cake, tow (for example, on a metal net), or continuously as a thread between rollers, but the equipment can be simplified and productivity can be improved. It is preferable to carry out in the form of a package in which fibers are wound around a core from the point.

  When performing solid-phase polymerization in the form of a package, it is important to prevent fusion that becomes prominent when the single fiber fineness is reduced. For this reason, it is possible to reduce the winding density of the fiber package when performing solid-phase polymerization. preferable. On the other hand, if the winding density is too small, the package is collapsed or the end face is fallen, and when the fiber is unwound at a constant speed after solid-phase polymerization, tension fluctuations and yarn breakage are caused. Therefore, in order to obtain the fiber of the present invention, it is important to obtain a package having a low winding density and less unwinding and falling.

  Forming such a package by winding by melt spinning is desirable in order to improve equipment productivity and production efficiency, but it is better to rewind and form the spinning yarn while adjusting the winding shape and winding tension. Is preferable because the winding density can be reduced.

  In rewinding, the spinning yarn is unwound and wound by a winder. The general control method of the winder is to control the speed of the winder by detecting the tension or speed via a speed control roller. However, the tension detection method increases the winding tension, and the speed detection method In the case of a liquid crystal polyester fiber having a small elongation and a high elastic modulus, a tension fluctuation due to a minute change in speed becomes large, causing a problem of falling and thread breakage. For this reason, it is preferable that the rewinding is performed directly from the spinning yarn package by a winder having a controlled rotation speed without using a speed control roller. In this case, the yarn speed may gradually change over time, but the change in a short time is small, the tension can be kept at a low value, the winding density is small, A package with less twilight can be obtained.

  Since the winding density can be reduced as the winding tension is reduced, it is preferably 1.0 cN / dtex or less, more preferably 0.60 cN / dtex or less. The lower limit is not particularly defined, but the lower limit that can be reached in the present invention is about 0.10 cN / dtex.

  A winding speed of 500 m / min or less, particularly 400 m / min or less is effective for lowering the winding density. On the other hand, a higher winding speed is advantageous for productivity. / Min or more, and particularly preferably 200 m / min or more. Note that in the method of winding directly with a winder having a controlled number of revolutions during rewinding, the speed may change over time, but the winding speed in this case indicates the maximum speed.

  In winding, it is important to reduce the contact pressure (surface pressure) of a contact roll or the like used to adjust the package shape and stabilize the winding tension. The contact pressure is preferably 400 gf or less, more preferably 200 gf or less. It is. If the contact pressure is excessively low, the contact roll floats from the package and falls, so the contact pressure is preferably 50 gf or more. The contact pressure is also related to the contact length between the contact roll and the package (also referred to as a winding stroke or a traverse length). The longer the contact length, the higher the contact pressure needs to be. The longer the contact length, the higher the winding amount of the package. Therefore, the contact length is preferably 100 mm or more. On the other hand, if the contact length is excessively long, the variation in tension at the end face during unraveling after solid phase polymerization becomes large, so the contact length is preferably 500 mm or less.

  In order to form a package with less traversing even in low tension winding, the winding form is preferably a tapered end winding with both ends tapered. At this time, the taper angle is preferably 70 ° or less, and more preferably 60 ° or less. Further, when the taper angle is small, the fiber package cannot be enlarged, and therefore, 30 ° or more is preferable, and 40 ° or more is more preferable. The taper angle referred to in the present invention is defined by the following equation.

  The number of winds is also important for preventing fusion. The number of winds referred to here is the number of times the spindle rotates during a half-reciprocation of the traverse, and is defined by the product of the time (minutes) of the traverse half-reciprocation and the spindle rotation speed (rpm). Indicates that the corner is small. The smaller the number of winds, the smaller the contact area between the fibers, which is advantageous for avoiding fusion. However, the higher the number of winds, the lower the end face in conditions such as low tension and low contact pressure, which are suitable winding conditions in the present invention. Can be reduced, and the package shape is improved. From these points, the wind number is preferably 3.0 or more and 15.0 or less, and more preferably 5.0 or more and 10.0 or less.

  In the present invention, the winding density of the package subjected to solid phase polymerization is preferably 0.60 g / cc or less. Here, the winding density is a value calculated by Wf / Vf from the occupied volume Vf (cc) of the package and the weight Wf (g) of the fiber obtained from the outside dimension of the package and the size of the bobbin serving as the core material. The occupied volume Vf is a value obtained by actually measuring the outer dimension of the package or by taking a photograph and measuring the outer dimension on the photograph and assuming that the package is rotationally symmetric. Wf is the fineness And a value calculated from the winding length, or a value measured by a weight difference before and after winding. The lower the winding density, the weaker the adhesion between the fibers in the package and the lower the fusion, so 0.50 g / cc or less is more preferable. Further, if the winding density is excessively small, the package will be collapsed or the end face will fall, so that it is preferably 0.05 g / cc or more, more preferably 0.20 g / cc or more.

  The bobbin used to form the fiber package may be any cylindrical one as long as it has a cylindrical shape. When the bobbin is wound, the bobbin is attached to a winder and rotated to wind the fiber to form a package. In the solid-phase polymerization, the fiber package can be processed integrally with the bobbin, but the bobbin alone can be extracted from the fiber package for processing. When the treatment is carried out while being wound around the bobbin, the bobbin needs to withstand the solid phase polymerization temperature, and is preferably made of a metal such as aluminum, brass, iron or stainless steel. Further, in this case, it is preferable that the bobbin has a large number of holes because the polymerization reaction by-products can be removed quickly and solid phase polymerization can be performed efficiently. Further, when the bobbin is extracted from the fiber package and processed, it is preferable to attach an outer skin to the bobbin outer layer. In any case, it is preferable that a cushion material is wound around the outer layer of the bobbin, and the liquid crystalline polyester melt-spun fiber is wound thereon. The material of the cushion material is preferably a felt made of organic fibers having high heat resistance, for example, para-aramid fiber or meta-aramid fiber, in order to prevent fusion with the liquid crystalline polyester during solid phase polymerization, and the thickness is preferably 0.1 mm or more and 20 mm or less. . The aforementioned outer skin can be substituted with the cushion material.

  The yarn length of the package subjected to solid phase polymerization is preferably 150,000 m or more, and more preferably 200,000 m or more in order to improve productivity and continuity in high-order processing. The fiber weight is preferably 15 g or more, more preferably 100 g or more. In each case, the upper limit is not particularly defined, but the upper limit that can be reached in the present invention is about 4 million m and 20 kg.

  In order to prevent fusion at the time of solid-phase polymerization, it is also important to attach an oil component and a release agent (hereinafter both referred to as an oil component) to the fiber surface. The oil may be attached during the period from melt spinning to winding, but in order to increase the adhesion efficiency, it is performed at the time of rewinding the spinning yarn, or a small amount is adhered by melt spinning, and further at the time of rewinding. It is preferable to add.

  The oil adhering method may be a guide oil supply method, but in order to uniformly adhere to a fiber having a fine total fineness such as a monofilament, adhesion with a metal or ceramic kiss roll (oiling roll) is preferable. As the oil component, it is better to have high heat resistance because it is not volatilized by high-temperature heat treatment in solid phase polymerization, and inorganic substances such as salt, talc, smectite, fluorine compounds, siloxane compounds (dimethylpolysiloxane, diphenylpolysiloxane, Methylphenyl polysiloxane and the like) and mixtures thereof are preferred. Of these, siloxane compounds are particularly preferred because they have an effect on slipperiness in addition to the effect of preventing fusion in solid phase polymerization.

  These components may be solid-coated or directly coated with liquid. However, emulsion coating is preferable for uniform coating while optimizing the amount of coating, and water emulsion is particularly preferable from the viewpoint of safety. Therefore, it is desirable that the component is water-soluble or easily form a water emulsion, and a mixed oil agent mainly composed of a water emulsion of dimethylpolysiloxane and a salt or water-swellable smectite added thereto is most preferable.

  The amount of oil attached to the fiber is preferably 2.0% by weight or more, and more preferably 4.0% by weight or more because the larger the oil content, the more the fusion can be suppressed. On the other hand, if the amount is too large, the fiber deteriorates the sticky handling and also deteriorates the process passability in the subsequent step, so 10.0% by weight or less is preferable, and 6.0% by weight or less is more preferable. In addition, the oil adhesion amount to a fiber refers to the value calculated | required by the method described in the Example.

  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.

  As for the solid phase polymerization temperature, when the endothermic peak temperature of the liquid crystal polyester fiber to be subjected to the solid phase polymerization is Tm1 (° C.), it is preferable that the highest temperature is Tm 1-60 ° C. or higher. By setting the temperature close to the melting point, solid phase polymerization can proceed rapidly and the strength of the fiber can be improved. In addition, Tm1 said here is generally melting | fusing point of liquid crystalline polyester fiber, and points out the value calculated | required by the measuring method of an Example in this invention. It is preferable that the maximum temperature is less than Tm1 (° C.) in order to prevent fusion. Further, it is more preferable to raise the solid-phase polymerization temperature stepwise or continuously with respect to time because it can prevent fusion and increase the time efficiency of solid-phase polymerization. In this case, 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 about Tm1 + 100 ° C. of the liquid crystal polyester fiber before the solid phase polymerization. However, even in this case, the maximum attainable temperature in the solid-phase polymerization is Tm1-60 (° C.) or more and less than Tm1 (° C.) of the fiber after the solid-phase polymerization, so that the solid-phase polymerization rate can be increased and fusion can be prevented. To preferred.

  The solid phase polymerization time is preferably 5 hours or more at the maximum temperature, and more preferably 10 hours or more, in order to sufficiently increase the molecular weight, that is, strength, elastic modulus, and elongation of the fiber. On the other hand, the effects of increasing the strength, elastic modulus, and elongation are saturated with the elapsed time.

  Next, the fibers are unwound from the solid-state polymerized package. In order to suppress fibrillation at the time of peeling off the slight fusion produced by solid-phase polymerization, while rotating the solid-state polymerization package, It is preferable that the yarn is unwound by so-called side-drawing, in which the yarn is unwound in the vertical direction (fiber circumferential direction). When the solid phase polymerization package is rotated actively with a constant rotational speed using a motor, etc., the winding diameter decreases with the unwinding and the speed gradually decreases. However, there is a problem that processing at a constant speed cannot be performed. For this reason, the rotation of the solid-state polymerization package can be controlled by a controlled unwinding method in which the number of rotations is controlled using a dancer roller, but when the solid-state polymerization yarn having poor wear resistance passes through the dancer roller, it is fibrillated. Therefore, solid-state polymerization packages are not actively driven, and it is possible to unwind the solid-state polymerization yarns while suppressing the fibrillation of the solid-state polymerization yarns by placing the solid-state polymerization package on the free roll and pulling the fibers with a speed control roller. It is preferable because it can be dredged. A free roll is composed of a shaft, a bearing, and an outer layer, but because the braking action works due to the sliding resistance of the bearing, the rotational speed changes slightly although it is almost constant, suppressing fluctuations in unwinding tension. It can be done.

  Since the melted solid phase polymerized yarn has an oil component for preventing fusion, it is preferably removed. Oil is effective in suppressing fusion, but if there is too much oil in the processes after solid-phase polymerization or weaving, deterioration of process passability due to deposition on guides, etc., and generation of defects due to inclusion of deposits in products For this reason, it is preferable to reduce the oil adhesion amount. That is, by removing the oil adhering before solid-phase polymerization after solid-phase polymerization, it is possible to achieve both fusion suppression, improvement in fineness in the longitudinal direction, uniformity of strength, and improvement in process passability.

  Examples of the oil removing method include a method of wiping with a cloth or paper while continuously running the fiber. However, when a mechanical load is applied to the solid-phase polymerized yarn, it is fibrillated so that the oil can be dissolved or dispersed. A method of immersing the fiber in is preferable. At this time, in order to increase the throughput per unit time, the fiber may be immersed in a liquid in a package state, but in order to perform uniform removal in the longitudinal direction of the fiber, the fiber is continuously run while the fiber is running. It is preferable to immerse. The method of continuously immersing the fiber in the liquid may be a method of guiding the fiber into the bath using a guide or the like, but in order to suppress fibrillation of the solid-phase polymerized fiber due to contact resistance with the guide, slits are provided at both ends of the bath. It is preferable to allow the fiber to pass through the slit through the slit and not to provide a yarn path guide in the bath.

  The liquid used for removal is preferably water in order to reduce the environmental load. The higher the temperature of the liquid, the higher the removal efficiency. The temperature is preferably 30 ° C or higher, more preferably 40 ° C or higher. However, if the temperature is too high, the liquid will evaporate significantly, so the boiling point of the liquid is preferably −20 ° C. or lower, more preferably the boiling point of −30 ° C. or lower.

  For example, a nonionic / anionic surfactant is preferably added to the liquid used for removal depending on the oil content. The addition amount of the surfactant is preferably 0.01 to 1% by weight, more preferably 0.1 to 0.5% by weight in order to increase the removal efficiency and reduce the environmental load.

  The method of immersing the liquid crystal polyester fiber in a liquid in a package state and unwinding it as it is is a preferable embodiment because the oil component can be efficiently removed. In particular, by continuously unwinding from the package after solid-phase polymerization and high-temperature heat treatment process, it is not necessary to wind up the liquid crystalline polyester fiber before high-temperature heat treatment, which has a small amount of oil adhering and is likely to cause fluff due to scratching. This is a preferred embodiment because liquid crystal polyester fibers after high-temperature heat treatment with reduced oil adhesion amount can be obtained while maintaining the above.

  At this time, the liquid crystal polyester fiber unraveled from the package immersed in the liquid leaves an undried liquid or a solution of the modified oil agent applied before solid-phase polymerization on the surface of the liquid crystal polyester fiber. It is also a preferred aspect to use and blow away or to rinse. So-called stains such as undried liquids and dissolved product of oil-modified products applied before solid-phase polymerization, when they remain on the surface of the liquid crystal polyester fiber, will eventually dry and become scum components. As a result, oil adhering to the surface of the liquid crystal polyester fiber can be reduced, and fluctuations in the unwinding tension due to the occurrence of scum can be suppressed.

  Therefore, the fluid used for blowing off is preferably air or water. In particular, when air is used as the fluid, it is possible to expect the effect of drying the liquid crystal polyester fiber surface, so that it is possible to prevent the accumulation of dirt in the subsequent process, that is, the yield can be improved. Therefore, this is a preferred embodiment.

  The fluid used for rinsing is preferably water. The rinsing is performed for the purpose of removing undried dirt and washing water adhering to the surface of the liquid crystal polyester fiber. Therefore, when water that can dissolve the dirt is used, washing can be performed efficiently. It is also a preferred embodiment to warm water for the purpose of increasing the solubility of dirt in water. The upper temperature is not particularly limited because the higher the temperature, the higher the solubility and the higher the efficiency of rinsing.Therefore, the energy consumption required for heating should be reduced and the energy cost reduced. Considering the loss due to evaporation, 80 ° C. is a good guideline.

  A combination of rinsing and blowing off is also a preferred embodiment. By combining dissolution removal by rinsing and removal of water remaining on the surface of the liquid crystal polyester fiber by blowing away, it becomes possible to remove oil more efficiently. The combination in this case becomes a more preferable aspect when rinsing is first performed to dissolve and remove the dirt, and then blown off.

  Furthermore, in order to increase the removal efficiency, it is preferable to impart vibration / liquid flow to the liquid used for removal. In this case, there is a method of ultrasonically vibrating the liquid, but it is preferable to apply a liquid flow from the viewpoint of simplifying the equipment and saving energy. There are liquid flow application methods such as stirring in the liquid bath and liquid flow application at the nozzle, but it can be easily implemented by supplying with the nozzle when circulating in the liquid bath. Is preferred.

  The degree of oil removal is appropriately adjusted according to the purpose, but it is preferably 2.0% by weight or less as the oil adhesion amount from the viewpoint of improving the processability of the fiber in the high-order processing step and the weaving step. In addition, the amount of oil adhesion refers to the value calculated | required by the method described in the Example.

  However, liquid crystal polyester fibers that have not been subjected to high-temperature heat treatment after solid-phase polymerization with an oil adhesion amount of less than 0.5% by weight are prone to fluff due to rubbing, so avoid rubbing as much as possible in the process before high-temperature heat treatment. Is a preferred embodiment from the viewpoint of fluff suppression. In particular, since the guide for regulating the yarn path is directly abraded with the liquid crystal polyester fiber, it is preferable to use a rotary guide. Furthermore, it is also one of preferred embodiments to avoid the portion where the liquid crystal polyester fiber is bent as much as possible, and therefore it is preferable to configure the process linearly.

  Next, in order to obtain a fiber having a peak half-value width of 15 ° C. or higher at Tm1 of the present invention, the liquid crystal polyester solid phase polymerized yarn is subjected to high temperature heat treatment. In addition, in order to obtain a fiber having U% H of less than 10% according to the present invention, high-temperature heat treatment is performed without unwinding and then removing the oil from the solid-phase polymerization package. This reason is as described in the prior art and is an important technical point for obtaining the fiber of the present invention.

  In order to perform high-temperature heat treatment without unwinding after removing the oil from the solid-phase polymerization package, for example, a method in which the fiber from which oil has been removed is once received in a can, and the fiber is taken out from the can and subjected to high-temperature heat treatment. However, since the tension fluctuation at the time of take-out is large, in order to increase the stability of the processing tension and to improve the uniformity of the fiber diameter in the longitudinal direction, continuous high-temperature heat treatment is applied after unraveling and oil removal. Is preferred. In particular, liquid crystal polyester fibers with an oil adhesion amount of less than 0.5% by weight are prone to fluff due to rubbing during high temperature heat treatment. In addition to reducing scratches during the process, it is possible to simplify the process, and further suppress the occurrence of scum on the guide part, and can also be expected to reduce the frequency of yarn breakage during the process. is there.

  In order to perform high temperature heat treatment continuously after unwinding and oil removal, it is necessary to keep the unwinding speed constant. For this purpose, it is important that the solid-phase polymerization package has little falling and no collapse. It becomes. For this purpose, it is effective to increase the winding density and apply a surface pressure to wind up. In that case, however, the adhesion between the fibers is increased, so that the fibers are easily fused at the time of solid phase polymerization, resulting in problems such as deterioration of the uniformity in the fiber longitudinal direction. In the prior art, emphasis was placed on reducing the winding density to the limit to suppress fusion, and this was achieved by reducing the winding tension without applying surface pressure. In that case, the end face is likely to fall, so the taper angle is reduced and the traverse is periodically swung to intentionally collapse the end face to adjust the entire winding shape. However, when the end face is broken, that is, when the fiber is rolled up on the taper portion of the package, the diameter changes at the taper portion. Therefore, in unwinding at a constant speed, it is necessary to change the rotation speed of the bobbin between the taper portion and the center portion. is there. Such control of the rotational speed is not possible with a liquid crystal polyester solid-phase polymerized fiber that is particularly low in elongation and inferior in abrasion resistance. Therefore, in the prior art, the solid-state polymerized package is actively driven and the speed is constant. It was unraveled that the tension of the things that were not there was almost constant.

  On the other hand, in order to obtain the fiber of the present invention, a surface pressure is applied at a low level in the rewinding before solid-phase polymerization, and the traverse is not shaken so that a package with a low winding density and a small amount of falling is obtained. In this way, unwinding at a constant speed becomes possible, and continuous processing of unwinding-oil removal-high temperature heat treatment becomes possible. At this time, although the winding density is low, it is higher than that of the prior art, so that it is easy to fuse. However, the adhesion can be suppressed by increasing the oil adhesion amount for solid phase polymerization. Furthermore, after the solid phase polymerized yarn is unwound, the final amount of adhesion to the fiber can be lowered by removing the oil.

  The high temperature heat treatment of the solid phase polymerized fiber is preferably at a temperature of Tm1 + 10 ° C. or higher. In addition, Tm1 said here points out the value calculated | required by the measuring method of an Example description. Although Tm1 is the melting point of the fiber, when the liquid crystal polyester fiber is heat-treated at a high temperature of melting point + 10 ° C. or higher, the peak half width at Tm1 becomes 15 ° C. or higher, and the wear resistance is greatly improved. In addition, the effect becomes remarkable when the single fiber fineness is small.

  A rigid molecular chain such as liquid crystal polyester has a long relaxation time, and the inner layer also relaxes and the fiber melts during the time that the surface layer relaxes. For this reason, when we examined wear resistance improvement technology suitable for liquid crystal polyester fibers, in the case of liquid crystal polyester, it is not possible to relax the molecular chain but to reduce the crystallinity of the whole fiber and the integrity of the crystals by heating. It has been found that the wear resistance can be improved.

  In order to further reduce the crystallinity, it is necessary to heat the fiber to the melting point or more, but at such a high temperature in the thermoplastic synthetic fiber, particularly when the single fiber fineness is small, the strength and elastic modulus decrease, Furthermore, it is thermally deformed and melted (melted). Although such behavior is also observed in liquid crystal polyester, the present inventors have low molecular mobility due to the increase in molecular weight due to increase in molecular weight of liquid crystal polyester fiber, and heat treatment at a temperature higher than the melting point. Even in such a short time, it was found that the degree of crystallinity can be reduced while maintaining the molecular chain orientation at a high level, and the decrease in strength and elastic modulus is small. For these reasons, liquid crystal polyester fibers with particularly small single yarn fineness are subjected to high-temperature heat treatment at Tm1 + 10 ° C or higher for a short time, thereby improving the wear resistance without significantly impairing the strength, elastic modulus, and heat resistance of the liquid crystal polyester fibers. I found what I could do.

  The high-temperature heat treatment temperature is more preferably Tm1 + 40 ° C. or higher for solid-phase polymerized fibers and lower than Tm1 + 60 ° C. for solid-phase polymerized fibers in order to reduce fiber crystallinity and crystal integrity. More preferably, Tm1 + 80 ° C. or higher is particularly preferable. The upper limit of the treatment temperature is the temperature at which the fiber melts, and it is about Tm1 + 300 ° C., although it varies depending on the tension, speed, single fiber fineness, and treatment length.

  Conventionally, there is an example in which the heat treatment of the liquid crystalline polyester fiber is performed, but since the liquid crystalline polyester is thermally deformed (flowed) by stress even at a temperature lower than the melting point, it is generally performed at a temperature lower than the melting point. In terms of heat treatment, there is solid-state polymerization of liquid crystalline polyester fiber, but even in this case, the fiber will be fused and blown unless the treatment temperature is lower than the melting point of the fiber. In the case of solid-phase polymerization, the melting point of the fiber increases with the treatment, so the final solid-phase polymerization temperature may be equal to or higher than the melting point of the fiber before the treatment. It is lower than the melting point, that is, the melting point of the fiber after heat treatment.

  The high-temperature heat treatment in the present invention does not perform solid-phase polymerization, but reduces the structural difference between the dense crystal portion and the amorphous portion formed by solid-phase polymerization, that is, decreases the crystallinity and crystal integrity. This increases the wear resistance. Therefore, even if Tm1 changes due to heat treatment, the treatment temperature is preferably Tm1 + 10 ° C. or higher of the fiber after the change. From this point, the treatment temperature is preferably Tm1 + 10 ° C. or higher of the fiber after the treatment, and Tm1 + 40 ° C. or higher. Is more preferable, Tm1 + 60 ° C. or higher is further preferable, and Tm1 + 80 ° C. or higher is particularly preferable.

  Another heat treatment is the thermal stretching of liquid crystalline polyester fiber, but the thermal stretching is to tension the fiber at high temperature, the fiber structure has higher molecular chain orientation, the strength and elastic modulus increase, and the crystallization The degree of crystal integrity is maintained, that is, ΔHm1 remains high, and the peak half-value width of Tm1 remains small. Therefore, the heat treatment of the present invention aims to improve the abrasion resistance by reducing the crystallinity (decreasing ΔHm1) and decreasing the crystal perfection (increasing the peak half-value width), resulting in a fiber structure inferior in abrasion resistance. Is different. The high temperature heat treatment referred to in the present invention does not increase the strength and elastic modulus because the crystallinity is lowered.

  The high temperature heat treatment is preferably performed while continuously running the fibers because fusion between the fibers can be prevented and the uniformity of the treatment can be improved. At this time, non-contact heat treatment is preferably performed in order to prevent generation of fibrils and perform uniform treatment. Heating means include atmospheric heating and radiant heating using laser and infrared rays, but heating with a slit heater using a block or plate heater has both the effects of atmospheric heating and radiant heating, increasing the stability of processing. Therefore, it is preferable.

  The treatment time is preferably longer in order to lower the crystallinity and crystal perfection, preferably 0.01 seconds or more, more preferably 0.05 seconds or more, and further preferably 0.1 seconds or more. Further, the upper limit of the treatment time is preferably 5.0 seconds or less, more preferably 3.0 seconds or less, because the equipment load is reduced, and if the treatment time is long, the orientation of the molecular chain is relaxed and the strength and elastic modulus are lowered. Preferably, it is 2.0 seconds or less.

  When the fiber tension at the time of processing is excessively high, fusing is likely to occur, and when heat treatment is performed in an excessive tension state, the effect of improving wear resistance is low because the decrease in crystallinity is small. It is preferable to make the tension as low as possible. This is clearly different from thermal stretching. However, if the tension is low, the fiber travel becomes unstable and the treatment becomes non-uniform, so 0.001 cN / dtex or more and 1.0 cN / dtex or less is preferable, and 0.1 cN / dtex or more and 0.3 cN / dtex or less. More preferred.

  When heat treatment is performed while running, the tension is preferably as low as possible, but stretching and relaxation may be added as appropriate. However, if the tension is too low, the fiber travel becomes unstable and the treatment becomes non-uniform, so the relaxation rate is preferably 2% or less (stretching ratio 0.98 times or more). Also, when the tension is high, fusing due to heat is likely to occur, and when heat treatment is performed in an excessive tension state, the reduction in crystallinity is small and the effect of improving wear resistance is low. Depending on the temperature, it is preferably less than 10% (stretching ratio: 1.10 times). More preferably, it is less than 5% (stretching ratio: 1.05 times), more preferably less than 3% (1.03 times).

  Although the treatment speed depends on the treatment length, the higher the speed, the higher the temperature and short time treatment becomes possible, and the effect of improving wear resistance is further enhanced, and the productivity is also improved, preferably 100 m / min or more, more preferably 200 m / min or more, More preferably, it is 300 m / min or more. The upper limit of the processing speed is about 1000 m / min from the running stability of the fiber.

  The treatment length depends on the heating method, but in the case of non-contact heating, it is preferably 100 mm or more, more preferably 500 mm or more in order to perform uniform treatment. Further, if the treatment length is excessively long, treatment unevenness and fiber fusing occur due to yarn swaying inside the heater, preferably 3000 mm or less, and more preferably 1000 mm or less.

  It is preferable that the amount of oil for solid-phase polymerization of the fiber to be subjected to high-temperature heat treatment is low, but the fiber after high-temperature heat treatment to be a product improves the processability after the next step and further improves the weaving property on the loom. Therefore, it is preferable to add a process oil for improving smoothness. As the oil component, known substances can be used. For example, a water emulsion of a smoothing agent mainly composed of a polyether compound and an emulsifier mainly composed of lauryl alcohol can be mentioned.

  Here, the fiber structure change in the high temperature heat treatment will be described from the difference in fiber characteristics before and after the treatment.

  This heat treatment is a heat treatment for a short time at a temperature higher than the melting point of the fiber, and the crystallinity is lowered but the orientation is not relaxed. This is shown by the structural change in which ΔHm1 decreases, the half width at Tm1 increases, Δ2θ increases, but Δn hardly changes by heat treatment. Moreover, since the processing time is short, the molecular weight does not change. A decrease in crystallinity generally causes a significant decrease in mechanical properties, and even in the heat treatment of the present invention, the strength and elastic modulus do not increase but decrease, but the method of the present invention has a high molecular weight and orientation. Therefore, the strength and elastic modulus are maintained at a high level, and the high melting point (Tm1) and heat resistance are maintained. Further, the compression elastic modulus is lowered by the heat treatment. The improvement in wear resistance is due to the fact that the entire fiber is softened due to the decrease in crystallinity and the structural difference between crystal / amorphous that is the starting point of fracture decreases. Abrasion resistance is increased.

  The liquid crystalline polyester fiber of the present invention has characteristics of high strength, high elastic modulus, and high heat resistance, and has improved wear resistance. General industrial materials, civil engineering / building materials, sports applications, protective clothing, Widely used in fields such as rubber reinforcement materials, electrical materials (especially as tension members), acoustic materials, and general clothing. Effective applications include screen kites, filters, ropes, nets, fishnets, computer ribbons, printed circuit board fabrics, paper canvases, airbags, airships, dome fabrics, rider suits, fishing lines, various lines (Yachts, paragliders, balloons, kites), blind cords, support cords for screen doors, various cords in automobiles and aircraft, power transmission cords for electrical products and robots, etc. Monofilaments to be used are mentioned, and among them, there is a strong demand for high strength, high elastic modulus and fineness, and it is most suitable for monofilaments for printing screens that require abrasion resistance to improve weaving and fabric quality.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this. The various characteristics of the present invention were evaluated by the following methods.

(1) Weight average molecular weight in terms of polystyrene (molecular weight)
A mixed solvent of pentafluorophenol / chloroform = 35/65 (weight ratio) was used as a solvent, and the solution was dissolved so that the concentration of liquid crystal polyester was 0.04 to 0.08 weight / volume% to obtain a sample for GPC measurement. In addition, when there was an insoluble matter even after standing at room temperature for 24 hours, the mixture was left still for 24 hours, and the supernatant was used as a sample. This was measured using a GPC measuring apparatus manufactured by Waters, and the weight average molecular weight (Mw) was determined by polystyrene conversion.
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
(2) Tm1, Tm1 peak half-width, ΔHm1, Tc, ΔHc, Tm2, ΔHm2 of liquid crystal polyester fiber, melting point of liquid crystal polyester polymer Differential calorimetry was carried out by DSC2920 manufactured by TA instruments, and 50 ° C to 20 ° C / min. The temperature of the endothermic peak observed when measured under the temperature raising condition was Tm1 (° C.), and the peak half-value width (° C.) and heat of fusion (ΔHm1) (J / g) at Tm1 were measured.

  In this measurement, the presence or absence of an exothermic peak was determined, and when a peak was observed, the calorific value was determined. Subsequently, after observing Tm1, holding at a temperature of Tm1 + 20 ° C. for 5 minutes, the temperature of an exothermic peak observed when measured under a temperature drop condition of 20 ° C./min is defined as Tc (° C.), and the amount of crystallization heat at Tc (ΔHc) (J / g) was measured. Subsequently, the mixture was cooled to 50 ° C., and the endothermic peak observed when the temperature was again measured at 20 ° C./min was defined as Tm2, and the heat of fusion (ΔHm2) (J / g) at Tm2 was measured.

  In addition, about the liquid crystalline polyester polymer shown in the reference example, after observing Tm1, it was held at a temperature of Tm1 + 20 ° C. for 5 minutes, then cooled to 50 ° C. under a temperature decreasing condition of 20 ° C./minute, and again increased to 20 ° C./minute. The endothermic peak observed when measured under temperature conditions was defined as Tm2, and Tm2 was defined as the melting point of the polymer.

(3) Fluctuation waveform with half inert diagram mass waveform (U% H) in Worcester yarn unevenness testing machine 5 minutes at 200 m / min without using a twister by using Zellerweger Worcester yarn unevenness testing machine UT-4 Measure and obtain half inert diagram mass waveform. A single fiber package is measured three times within 10,000 m from the outermost layer and three times within 10,000 m from the innermost layer to obtain a total of six waveforms per fiber package. The fluctuation peak having the largest absolute value in each waveform is read from the chart, and the absolute value of the maximum value among the six waveforms is defined as the U% H fluctuation waveform (%) of the sample.

(4) Fluctuation value in outer diameter measurement Using an external shape measuring instrument D-6101 ROSSDORF1 manufactured by Zimmer, measurement is performed at 400 m / min for 3 minutes under the condition of a sampling rate of 0.002 seconds. A single fiber package is measured three times within 10,000 m from the outermost layer and three times within 10,000 m from the innermost layer, and a total of six outer diameter measurements are performed per fiber package. For one data group of outer diameter measurement results, the difference (deviation) from the average value of the entire data is obtained, and the fluctuation value (%) is obtained from the value having the largest absolute value and the average value by the following formula. Of the six outer diameter measurement results, the absolute value of the largest absolute value of the fluctuation value is defined as the fluctuation value (%) in the outer diameter measurement of the sample.

(Deviation with the maximum absolute value) × 100 / average value = variation value (%)
(5) Single fiber fineness and fineness fluctuation rate Take 10 m of fiber with a measuring instrument, multiply the weight (g) by 1000, measure 10 times per level, and calculate the average value as fineness (dtex) did. The quotient obtained by dividing this by the number of filaments was defined as the single fiber fineness (dtex). The fineness variation rate was calculated by the following equation using the larger one of the absolute values of the difference between the maximum value and the minimum value from the average value of 10 finenesses.
Fineness fluctuation rate (%) = ((| maximum value or minimum value−average value | / average value) × 100)
(6) Strength, elongation, elastic modulus, and strength fluctuation rate According to the method described in JIS L1013: 1999, using Tensilon UCT-100 manufactured by Orientec Co., Ltd. under the conditions of a sample length of 100 mm and a tensile speed of 50 mm / min. The measurement was performed 10 times per average, and the average value was defined as strength (cN), strength (cN / dtex), elongation (%), and elastic modulus (cN / dtex). The strength fluctuation rate was calculated by the following formula using the larger one of the absolute values of the differences between the maximum and minimum values from the average value of 10 strengths.
Strong fluctuation rate (%) = ((| maximum or minimum value−average value | / average value) × 100)
(7) Compression modulus in the direction perpendicular to the fiber axis (compression modulus)
Place a single fiber on a highly rigid stage such as ceramic, and apply a compressive load at a constant test speed using the indenter in the diameter direction under the following conditions with the side of the indenter approximately parallel to the fiber. After obtaining the load-displacement curve, the compression elastic modulus in the direction perpendicular to the fiber axis was calculated from the following equation.

  In the measurement, in order to correct the deformation amount of the device system, a load-displacement curve is obtained without placing the sample, and this is approximated by a straight line to calculate the deformation amount of the device with respect to the load. -From the displacement of each data point when the displacement curve was measured, the amount of deformation of the apparatus with respect to the load was subtracted to obtain the displacement of the sample itself, which was used for the following calculation.

  In the calculation, the compression elastic modulus was calculated using the load and displacement at two points where linearity is established in the load-displacement curve. The point on the low load side is a point where the load is about 30 mN because there is a possibility that the indenter does not hit the entire surface of the sample at the initial stage when the load is applied. However, when the low load point determined here is in the non-linear region, a straight line is drawn on the low load side along the load-displacement curve so as to pass the yield point, and the deviation between the straight line and the displacement is within 0.1 μm. The minimum load point is The high load side was a point with a load of about 100 mN. When the point on the high load side exceeds the yield point load, a straight line is drawn on the high load side along the load-displacement curve so as to pass the point on the low load side, and the displacement deviation from that line is zero. The point of maximum load within 1 μm was taken as the point on the high load side. In addition, l in the following formula is calculated as 500 μm, and the single fiber radius is a value obtained by measuring the diameter of the sample 10 times using an optical microscope before the test and halving the average diameter obtained by averaging this. Was used. Further, the load-displacement curve was measured 5 times for the sample 1 level, the compression elastic modulus was also calculated 5 times, and the average of these was taken as the compression elastic modulus.

Apparatus: Instron super precision material testing machine Model 5848
Indenter: Diamond flat indenter (square with a side of 500 μm)
Test speed: 50 μm / min Sampling speed: 0.1 second Data processing system: “Merlin” manufactured by Instron
Measurement atmosphere: At room temperature in air (23 ± 2 ° C., 50 ± 5% RH)
(8) Peak half-width (Δ2θ) in wide-angle X-ray diffraction
The fiber was cut into 4 cm, 20 mg of the fiber was weighed and used as a sample. The measurement was performed in the equator direction with respect to the fiber axis direction, and the conditions were as follows. At this time, the half width (Δ2θ) of the peak observed at 2θ = 18 to 22 ° was measured.
X-ray generator: Rigaku Denki 4036A2 type X-ray source: CuKα ray (using Ni filter)
Output: 40kV-20mA
Goniometer: Rigaku Denki 2155D type slit: 2mmφ-1 ° -1 °
Detector: Scintillation counter counting recording device: RAD-C type measurement range manufactured by Rigaku Corporation: 2θ = 5-60 °
Step: 0.05 °
Integration time: 2 seconds (9) Birefringence (Δn)
Using a polarizing microscope (BLY-2 manufactured by OLYMPUS), measurement was performed 5 times per one sample level by the compensator method, and the average value was obtained.

(10) Wear resistance C
A fiber loaded with a load of 1.23 cN / dtex was hung vertically, and a ceramic bar guide (made by Yuasa Yido Co., Ltd., material YM-99C) with a diameter of 4 mm was contacted to be perpendicular to the fiber. Press at 2.7 °, rub the guide in the fiber axis direction at a stroke length of 30 mm and a stroke speed of 600 times / minute, observe with a stereomicroscope every 15 seconds, and generate white powder or fibrils on the bar guide or on the fiber surface Was measured, and the average value of five times excluding the maximum value and the minimum value among the seven measurements was determined as the wear resistance C. The abrasion resistance C was evaluated by the same test method for multifilaments.

(11) Judgment of oil adhesion amount and polysiloxane compound adhesion 100 mg or more of fibers were collected and weighed after drying for 10 minutes at 60 ° C. (W0), and water more than 100 times the fiber weight. The fiber was immersed in a solution containing 2.0% by weight of sodium dodecylbenzenesulfonate added to the fiber, ultrasonically washed at room temperature for 20 minutes, the washed fiber was washed with water, and dried at 60 ° C. for 10 minutes. The weight after the measurement was measured (W1), and the oil adhesion amount was calculated by the following formula.
(Amount of oil adhering (weight%)) = (W0−W1) × 100 / W1
In addition, the determination of polysiloxane compound adhesion was obtained by collecting a solution after ultrasonic cleaning, performing IR measurement, and determining the polysiloxane against the peak intensity of 1150 to 1250 cm ⁻¹ derived from the sulfonic acid group of sodium dodecylbenzenesulfonate. If the derived peak intensity of 1050 to 1150 cm ⁻¹ was 0.1 times or more, it was judged that the polysiloxane adhered to the fiber.

(12) Running tension and running stress Measured using a tension meter (MODEL TTM-101) manufactured by Toray Engineering. In addition, a tension meter capable of measuring a full scale of 5 g and an accuracy of 0.01 g was used for the extremely low tension. The measured traveling tension was converted into a unit and divided by the fineness of the treated fiber to obtain the traveling stress as a unit of cN / dtex.

(13) Weaving and evaluation of fabric characteristics Using a 13 dtex polyester monofilament for warp on a rapier loom, weaving density is set to 250 wefts / inch (2.54 cm), wefting speed is set to 100 times / min, weft Was weaved as a liquid crystal polyester fiber. At this time, the process passability is evaluated from the fibril and scum accumulation on the yarn feeder (ceramic guide) in the trial weaving of 180 cm in width and 5 m in length, and the weaving property is evaluated from the number of stops due to yarn breakage. The quality of the fabric was evaluated from the number of fibrils and scum mixed in. The criteria for each are described below. The thickness of the woven fabric was measured using a dial thickness gauge manufactured by Peacock.
<Process passability>
Even after weaving, no fibril or scum accumulation is observed; excellent (◎)
Fibrils and scum are observed after weaving, but there is no hindrance to fiber running; good (○)
Fibrils and scum are observed during weaving, and fiber running tension increases; Fail (△)
Fibrils and scum were observed during weaving, and trial weaving was stopped; defective (×)
<Weaving properties>
Stopping 5 times or less; Excellent (◎), 6 to 10 times; Good (◯), 11 times or more; Poor (x)
<Textile grade>
Number of fibrils and scum mixed in 5 or less; Excellent (◎), 6 to 10; Good (◯), 11 or more; Poor (×)
(14) Unwinding tension fluctuation rate TTM manufactured by Toray Engineering Co., Ltd. was used for the obtained liquid crystal polyester fiber at a speed of 400 m / min for 20 minutes through a Yuasa Yarnichi Washer Tensor Y-601L (using one metal pear washer). The tension of the running yarn was measured with a -101 type tension measuring device (without DAMPING). From the tension of the obtained traveling yarn, the unwinding tension fluctuation rate was calculated according to the following formula.

Unwinding tension fluctuation rate (%) = (Unwinding tension standard deviation) / (Average unwinding tension) x 100
(15) Thread Looseness The obtained liquid crystalline polyester fiber is creeled and pulled out through a Yuasa Yodo washer tensor Y-601L (one metal pear washer is used for each of the two bars), and the circumference is 1 m. The measuring instrument was wound 100 times at a speed of 100 m / min, and the obtained wound yarn was visually inspected to evaluate the slackness of the yarn.

  The evaluation was made with ○ indicating that no slack in the yarn was observed, Δ indicating that the slack was 5 or less, and × indicating that 6 or more slack was observed.

Reference example 1
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid Then, 1460 parts by weight of acetic anhydride (1.10 equivalents of 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 335 degreeC in 4 hours.

  The polymerization temperature was maintained at 335 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 40 minutes. When the torque reached 28 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference example 2
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid 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 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference example 3
In a 5 L reaction vessel equipped with a stirring blade and a distilling tube, 1008 parts by weight of p-hydroxybenzoic acid, 508 parts by weight of 6-hydroxy-2-naphthoic acid and 1071 parts by weight of acetic anhydride (1.05 mol of total phenolic hydroxyl groups) 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 with stirring in a nitrogen gas atmosphere, and then the reaction was carried out 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 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference example 4
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 38 parts by weight of 6-hydroxy-2-naphthoic acid, 259 parts by weight of 2,6-naphthalenedicarboxylic acid, 1022 parts by weight of p-hydroxybenzoic acid, 132 parts by weight of hydroquinone , And 1071 parts by weight of acetic anhydride (1.05 molar equivalents of the total phenolic hydroxyl group) were charged into a reaction vessel equipped with a stirring blade and a distillation tube, and stirred from room temperature to 145 ° C. in 30 minutes with stirring in a nitrogen gas atmosphere. After raising the temperature, the reaction was carried out at 145 ° C. for 2 hours. Then, it heated up to 335 degreeC in 4 hours.

  The polymerization temperature was maintained at 335 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 30 minutes. When the torque reached 20 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 5
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 808 parts by weight of p-hydroxybenzoic acid, 411 parts by weight of 4,4′-dihydroxybiphenyl, 104 parts by weight of hydroquinone, 314 parts by weight of terephthalic acid, 209 parts by weight of isophthalic acid Then, 1364 parts by weight of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups) was charged, 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 300 degreeC in 4 hours.

  The polymerization temperature was maintained at 300 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 6
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 323 parts by weight of p-hydroxybenzoic acid, 436 parts by weight of 4,4′-dihydroxybiphenyl, 109 parts by weight of hydroquinone, 359 parts by weight of terephthalic acid, 194 parts by weight of isophthalic acid Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 325 degreeC in 4 hours.

  The polymerization temperature was maintained at 325 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 7
895 parts by weight of p-hydroxybenzoic acid, 168 parts by weight of 4,4′-dihydroxybiphenyl, 40 parts by weight of hydroquinone, 135 parts by weight of terephthalic acid, 75 parts by weight of isophthalic acid in a 5 L reaction vessel equipped with a stirring blade and a distillation tube Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 365 degreeC in 4 hours.

  The polymerization temperature was maintained at 365 ° C., the pressure was reduced to 133 Pa in 1.5 hours, the reaction was continued for another 20 minutes, and the polycondensation was completed when the torque reached 15 kgcm. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 8
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 671 parts by weight of p-hydroxybenzoic acid, 235 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 224 parts by weight of terephthalic acid, 120 parts by weight of isophthalic acid Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 340 degreeC in 4 hours.

  The polymerization temperature was maintained at 340 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 9
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 671 parts by weight of p-hydroxybenzoic acid, 335 parts by weight of 4,4′-dihydroxybiphenyl, 30 parts by weight of hydroquinone, 224 parts by weight of terephthalic acid, 120 parts by weight of isophthalic acid Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 305 degreeC in 4 hours.

  The polymerization temperature was maintained at 305 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 10
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 671 parts by weight of p-hydroxybenzoic acid, 268 parts by weight of 4,4′-dihydroxybiphenyl, 69 parts by weight of hydroquinone, 314 parts by weight of terephthalic acid, 30 parts by weight of isophthalic acid Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 355 degreeC in 4 hours.

  The polymerization temperature was maintained at 355 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

Reference Example 11
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 671 parts by weight of p-hydroxybenzoic acid, 268 parts by weight of 4,4′-dihydroxybiphenyl, 69 parts by weight of hydroquinone, 150 parts by weight of terephthalic acid, 194 parts by weight of isophthalic acid Then, 1011 parts by weight of acetic anhydride (1.10 equivalents of 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 310 degreeC in 4 hours.

  The polymerization temperature was maintained at 310 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 20 minutes. When the torque reached 15 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  The characteristics of the liquid crystalline polyester obtained in Reference Examples 1 to 11 are shown in Table 1. Each resin was heated and heated in a nitrogen atmosphere on a hot stage, and the transmitted light of the sample was observed under polarized light. As a result, optical anisotropy (liquid crystallinity) was confirmed. The melt viscosity was measured using a Koka flow tester at a temperature of melting point + 10 ° C. and a shear rate of 1000 / s.

  The optimal embodiment of the liquid crystalline polyester fiber of this invention is demonstrated by Example 1 and Comparative Examples 1-4.

Example 1
After vacuum drying at 160 ° C. for 12 hours using the liquid crystal polyester of Reference Example 1, melt extrusion with a φ15 mm single screw extruder manufactured by Osaka Seiki Machine Co., Ltd., and supplying the polymer to the spinning pack while measuring with a gear pump did. In the spinning pack, the polymer was filtered using a metal nonwoven fabric filter, and the polymer was discharged from the die. The discharged polymer is allowed to pass through a 40 mm heat insulation region, and then cooled and solidified from the outside of the yarn with an annular cooling airflow at 25 ° C., and then mainly a smoothing agent mainly composed of a polyether compound and lauryl alcohol. The oil agent which consists of the water emulsion of the emulsifier made was given, and all the filaments were taken up by the 1st godet roll. After passing this through the second godet roll at the same speed, one of all the filaments is sucked with a suction gun, and the remaining one is passed through a dancer arm through a pirn winder (EFT take-up winder manufactured by Kozu Seisakusho, It was wound up in the shape of a pan with no contact roll in contact with the winding package. During winding, yarn breakage did not occur, and the yarn forming property was good. Table 2 shows the spinning conditions and the physical properties of the spun fiber.

From this spun fiber package, roll-back was performed before solid phase polymerization using an SSP-MV type rewinder (contact length: 200 mm, wind number: 8.7, taper angle: 45 °) manufactured by Kozu Seisakusho. Spinning fibers are unwound in the longitudinal direction (perpendicular to the fiber circulation direction), and do not use a speed control roller, but use an oiling roller (satin-finished stainless steel roll) to produce polydimethylsiloxane (manufactured by Dow Corning Toray). A water emulsion having SH 200) of 5.0% by weight was used as an oil agent, and refueling was performed. 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) was used, and the surface pressure was 100 gf. Table 3 shows the rewinding conditions.

  Next, the bobbin made of stainless steel was removed from the wound package, and solid state polymerization was performed in a package state in which the fiber was wound around Kevlar felt. In the solid-phase polymerization, the temperature is raised from room temperature to 240 ° C. in about 30 minutes using a closed oven, maintained at 240 ° C. for 3 hours, and then heated to the final temperature at 4 ° C./hour. The temperature program was held. The atmosphere was supplied with dehumidified nitrogen at a flow rate of 20 NL / min, and exhausted from the exhaust port so that the inside of the chamber was not pressurized. Table 3 also shows the solid-state polymerization conditions and solid-state polymerization fiber properties.

  Finally, the fiber was unwound from the package after the solid phase polymerization, continuously removed (washed), and subjected to high-temperature non-contact heat treatment. The package after solid-phase polymerization is fitted into a freeroll creel (having a shaft and a bearing, the outer layer part can freely rotate. There is no brake and drive source), and the yarn is pulled out in the lateral direction (fiber circulation direction) from here. Continuously, the fiber was passed through a bathtub provided with slits at both ends (without a guide contacting the fiber inside), and the oil agent was washed and removed. The cleaning liquid is 50 ° C. warm water containing 0.1% by weight of a nonionic / anionic surfactant (Granup US-30 manufactured by Sanyo Kasei Co., Ltd.). Supplied to. When supplying to the water tank, a pipe having holes formed every 5 cm was passed through the water tank, and a liquid flow was given to the water tank by supplying the pipe. A cleaning liquid overflowing from the slit and the liquid level adjusting hole is collected and returned to the external tank.

  The washed fiber was passed through a bearing roller guide and then passed through a first roller with a separate roller. In addition, since a creel is a free roll, by pulling a fiber with this roller, the unwinding from a solid phase polymerization package is performed and the fiber is run. The fiber that passed through the roller was passed through a slit heater and subjected to high temperature heat treatment. No guides are provided in the slit heater, and the heater and fiber are not in contact with each other. The fiber after passing through the heater was passed through a second roller with a separate roller. The first roller and the second roller were at the same speed. The fiber that has passed through the second roller is provided with an oil agent consisting of a smoothing agent mainly composed of a polyether compound and a water emulsion of an emulsifier mainly composed of lauryl alcohol by a ceramic oiling roller, and a winder (ET- 8T type speed-controlled winder, winding tension 15 gf, surface pressure 120 gf, taper angle 60 °, wind number 8.7, contact length 200 mm). Table 4 shows the conditions of unraveling, washing, high-temperature heat treatment, and fiber properties after high-temperature heat treatment. In addition, Δn of this liquid crystal polyester fiber was 0.35 and had a high orientation.

  As can be seen from Table 4, the fiber of Example 1 has high strength, high elastic modulus, high elongation, and high wear resistance. In addition, the fluctuation waveform of U% H and the fluctuation value of the outer diameter measurement are small, and the uniformity of the fiber diameter in the longitudinal direction is also excellent.

  Table 4 also shows the results of evaluation of the test fabric using this fiber. Since it has high abrasion resistance and excellent uniformity in the fiber diameter in the longitudinal direction, the process passability, weaving property, and textile quality were excellent. Since there is no abnormality in fiber diameter and opening, there are no defects when printing screens and filter meshes, and it can be expected to have good characteristics.

Comparative Example 1
The package after solid phase polymerization obtained by the same method as in Example 1 was unwound and washed in the same manner as in Example 1, and then wound once with an ET-8T type speed-controlled winder manufactured by Kozu Manufacturing Co., Ltd. I took it. In terms of the relationship with Example 1, it corresponds to winding after passing through the first roller. The winding conditions at this time were tension 15 gf, surface pressure 120 gf, taper angle 60 °, wind number 8.7, and contact length 200 mm. Initially, as in Example 1, unwinding and washing were performed at 400 m / min, and winding was performed. However, yarn breakage occurred frequently with the winder, and the speed was reduced to 200 m / min and wound. The fiber was drawn out from the wound fiber package in the longitudinal direction (perpendicular to the fiber circulation direction) and subjected to high-temperature heat treatment in the same manner as in Example 1. In terms of the relationship with Example 1, the package is placed in front of the first roller, and the fiber is fed by longitudinally unraveling. During the high-temperature heat treatment, fluff presumed to be fibrils was wound around the first roller, and in particular, in the latter half of the treatment, the yarn separation from the first roller became unstable and the running stability deteriorated. Table 4 shows the conditions of unraveling, washing, high-temperature heat treatment, and fiber properties after high-temperature heat treatment.

  As can be seen from Table 4, the fiber of Comparative Example 1 has high strength, high elastic modulus, high elongation, and high wear resistance. The variation value is large and the uniformity of the fiber diameter in the longitudinal direction is inferior. This is presumably because fibrils are generated by once winding the solid phase polymerized liquid crystal polyester fiber.

  The results of evaluation of the test fabric using this fiber are also shown in Table 4, but the process passability was rejected, the weaving property, and the fabric quality were poor. In particular, since the defect of the fabric quality was conspicuous in the second half of weaving, fibrillation, entrapping of fibril deposits, etc. were carried out in the inner layer part of the fiber after heat treatment, and hence the outer layer part once the fiber after solid phase polymerization was wound up. It is presumed that there were many defects, and the process passability, weaving property, and textile quality were deteriorated.

Comparative Example 2
From a spun fiber package obtained by the same method as in Example 1, the fiber is unwound in the longitudinal direction in the same manner as in Example 1 of Patent Document 2, and a winder (with a constant speed without using a speed control roller) Rewinding was performed using an ET-68S controlled winding machine manufactured by Kozu Seisakusho. The core material for rewinding was the same as in Example 1, but no surface pressure was applied, and the package form was a taper end winding with a taper angle of 20 °, and the traverse width was constantly swung by remodeling the taper width adjusting mechanism. did. Table 3 shows the rewinding conditions.

  This was subjected to solid phase polymerization in the same manner as in Example 1. The fiber physical properties after solid-phase polymerization are shown in Table 3. The physical property values at this stage are the same as in Example 1. An attempt was made to unwind and wash this in the same manner as in Example 1, but the yarn breakage occurred frequently, and the yarn breakage occurred even when the speed was reduced to 200 m / min.

  Thus, by the same method as in Example 1 of Patent Document 2, the end face is broken by constantly oscillating the taper width in rewinding before solid-phase polymerization, so that the end face is formed in the tapered portion, and the diameter is reduced. It is thought that the yarn breakage occurred because it became difficult to unwind at a constant speed.

Comparative Example 3
A package after solid phase polymerization obtained by the same method as in Comparative Example 2 (the same method as in Example 1 of Patent Document 2) is mounted on a delivery roll (motor-driven constant rotation delivery), and a speed control roller Without passing through, it was attempted to wind up by washing, high-temperature heat treatment, and additional oil in the same manner as in Example 1. However, when passing through a high-temperature heat treatment heater, the speed fluctuation of the winder increased, and yarn breakage occurred even at 200 m / min. It is considered that the winding tension is transmitted to the fibers in the high-temperature heat treatment, so that the heat treatment tension becomes excessively large and fusing occurs.

  As described above, in the same manner as in Example 1 of Patent Document 2, when the package after the solid-phase polymerization is sent out by the delivery roll, continuation of unraveling-cleaning-heat treatment cannot be performed, and the fiber of the present invention cannot be obtained. .

Comparative Example 4
Weaving evaluation was performed using the solid-state polymerized yarn obtained by the same method as in Comparative Example 1 without performing high-temperature heat treatment. The physical properties of the fibers are shown in Table 4, but the abrasion resistance is lowered by the washing as compared with the solid phase polymerized yarn. In the weaving evaluation, the yarn breakage and fibril accumulation became remarkable before weaving even 1 m, and the evaluation was stopped because of poor processability.

  Thus, high temperature heat treatment is not performed, and the liquid crystal polyester fiber having a peak half width at Tm1 of less than 15 ° C. is inferior in wear resistance, and inferior in high-order process passability and weaving.

Examples 2-4
Here, the fiber diameter (fineness) and the number of filaments were evaluated.

  Melt spinning was carried out in the same manner as in Example 1 except that the spinning conditions were those shown in Table 2. In Example 4, all the discharged filaments are rolled up together. Although the yarn forming property was good, in Example 2, the yarn breakage occurred once, so the yarn was threaded again, but no yarn breakage was observed thereafter. The obtained spinning fiber properties are also shown in Table 2.

  This was rewound before solid phase polymerization in the same manner as in Example 1 except that the rewinding conditions were the conditions shown in Table 3. Next, solid phase polymerization was performed in the same manner as in Example 1. The obtained solid state polymerized fiber properties are shown in Table 3.

  Unwinding, cleaning, and high temperature heat treatment were continuously performed in the same manner as in Example 1 except that the conditions of unraveling, cleaning, and high temperature heat treatment were changed to the conditions shown in Table 4. In Example 2, the yarn separation from the first roller became unstable and the running stability was slightly deteriorated, but the yarn breakage did not occur. Table 4 shows the fiber properties after the high-temperature heat treatment.

  Table 4 also shows the results of weaving evaluation using the obtained fibers. In Examples 3 and 4, the process passability, weaving property, and fabric quality were excellent. In Example 2, a standstill due to yarn breakage occurred immediately after the start of evaluation, and fibrils were mixed, but the latter half was smooth. This is probably because the abrasion resistance is slightly inferior, so that a slight amount of fibrils accumulates in the unraveling-cleaning-high temperature heat treatment process, and fibril deposits are mixed in the outer layer portion of the package after the high temperature heat treatment.

Examples 5-14
Here, the resin composition was evaluated.

  Using the liquid crystalline polyesters obtained in Reference Examples 2 to 11, melt spinning was performed in the same manner as in Example 1 except that the spinning conditions were as shown in Table 2. In Examples 6, 7, and 10, yarn breakage occurred once during spinning, but no yarn breakage occurred after re-threading. The obtained spinning fiber properties are shown in Table 2.

  Rewinding before solid phase polymerization was performed in the same manner as in Example 1 except that the rewinding conditions were set as shown in Table 3. Further, the solid phase polymerization was performed in the same manner as in Example 1 except that the final temperature of the solid phase polymerization was set to the conditions shown in Table 3. The obtained solid state polymerized fiber properties are shown in Table 3.

  Unwinding, cleaning, and high temperature heat treatment were continuously performed in the same manner as in Example 1 except that the conditions of unraveling, cleaning, and high temperature heat treatment were changed to the conditions shown in Table 4. In Examples 6 and 7, yarn separation from the first roller became unstable, and yarn breakage occurred once each. In Examples 13 and 14, running stability was slightly deteriorated, but yarn breakage did not occur. Table 4 shows the fiber properties after the high-temperature heat treatment.

  Table 4 also shows the results of weaving evaluation using the obtained fibers. In Example 5, the process passability, weaving property, and fabric quality were excellent. In Examples 6 to 14, a stop due to yarn breakage occurred immediately after the start of evaluation, and fibrils were mixed, but the latter half was smooth. This is probably because the abrasion resistance is slightly inferior, so that a slight amount of fibrils accumulates in the unraveling-cleaning-high temperature heat treatment process, and fibril deposits are mixed in the outer layer portion of the package after the high temperature heat treatment. In Examples 6 and 7, fibrils were deposited on the guides in the process after weaving. There were also a lot of stops due to thread breakage and fibrils. In Examples 6 and 7, since the abrasion resistance is inferior, the amount of fibrils generated is large, the fluctuation waveform of U% H, and the fluctuation value of the outer diameter measurement are slightly large. It seems that the result was slightly inferior in quality.

Example 15
A surfactant in which the winding time is 400 minutes and the amount of rewinding is 400,000 m among spinning conditions, and the package itself after solid phase polymerization is kept at 50 ° C. when unwinding from the package after solid phase polymerization. Immerse so that all layers of the wound yarn are buried in the washing bath, unwind while pulling the yarn in the longitudinal direction (perpendicular to the fiber circulation direction), and a bathtub (with fibers inside) The washing water containing the surfactant was rinsed and removed. To the bathtub, hot water at 50 ° C. that was temperature-controlled in an external tank was supplied by a pump. In addition, liquid crystal polyester fiber was obtained by the same method as Example 1 except having provided the mechanism which collect | recovered the warm water which overflowed from the slit and the liquid level adjustment hole, and returned to an external tank.

  The oil adhesion amount of the obtained liquid crystal polyester fiber was 0.05% by weight. Further, the unwinding tension fluctuation rate was 12.7%, and the unwinding tension fluctuation could be suppressed at an excellent level, and there was no yarn slack and good processability was exhibited.

  Further, there was no scum generation or yarn breakage during the production process of the liquid crystalline polyester fiber, and a winding package having a fiber length of 400,000 m could be obtained.

Example 16
A liquid crystal polyester fiber was obtained in the same manner as in Example 15 except that the temperature of the hot water was 18 ° C.

  The obtained liquid crystal polyester fiber had an oil adhesion amount of 0.26% by weight. The unwinding tension fluctuation rate was 19.1%, and the unwinding tension fluctuation could be suppressed at a good level, and there was almost no loosening of the yarn, and good processability was exhibited.

  Furthermore, there was little scum generation during the production process of the liquid crystal polyester fiber, and a winding package having a fiber length of 260,000 m on average could be obtained.

Example 17
A liquid crystal polyester fiber was obtained in the same manner as in Example 15 except that the rinsing bath provided with slits at both ends was not used.

  The oil adhesion amount of the obtained liquid crystal polyester fiber was 0.35% by weight. The unwinding tension fluctuation rate was 23.2%, and the unraveling tension fluctuation could be suppressed at a problem-free level, there was almost no slack in the yarn, and good processability was exhibited.

  Furthermore, there was little scum generation during the production process of the liquid crystalline polyester fiber, and a winding package having a fiber length of 220,000 m on average could be obtained.

Example 18
A liquid crystal polyester fiber was obtained in the same manner as in Example 15 except that the washing bath containing the surfactant was kept at 18 ° C.

  The obtained liquid crystal polyester fiber had an oil adhesion amount of 0.39% by weight. The unwinding tension fluctuation rate was 26.9%, and the unraveling tension fluctuation could be suppressed at a problem-free level, there was almost no slack in the yarn, and good processability was exhibited.

  Furthermore, there was little scum generation during the production process of the liquid crystal polyester fiber, and a winding package having a fiber length of 200,000 m on average could be obtained.

Claims (6)

  In differential calorimetry, the peak half-value width at the endothermic peak (Tm1) observed when measured under a temperature rising condition from 50 ° C. to 20 ° C./min is 15 ° C. or more, and the weight average molecular weight in terms of polystyrene is 25.0. A liquid crystal polyester fiber having a fluctuation waveform of less than 10% in a half inert diagram mass waveform in a Worcester yarn nonuniformity tester of 10,000 to 200,000.   2. The liquid crystal polyester fiber according to claim 1, wherein the liquid crystal polyester fiber is a monofilament.   The liquid crystal polyester fiber according to claim 1 or 2, wherein the oil content is less than 0.5% by weight.   A winding package comprising the liquid crystalline polyester fiber according to claim 1 or 2, wherein the wound fiber has a length of 150,000 m or more.   A printing screen made of a liquid crystal polyester fiber according to claim 1 or 2.   A mesh fabric for a filter comprising the liquid crystalline polyester fiber according to claim 1 or 2.