JP2017179647A - Liquid crystal polyester multifilament, manufacturing method therefor and high level processed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal polyester multifilament capable of solving conventional problems, i.e. one used suitably for general industrial material applications, and having high strength and high elastic modulus with improved raw yarn strength availability during high level processing.SOLUTION: The invention has a following structure for solving the above described problem. There is provided a liquid crystal polyester multifilament having actual yarn width ratio X calculated from percentage of actual yarn width B to theoretical yarn width A of a multifilament yarn stripe of 20 to 50%.SELECTED DRAWING: None

Description

  The present invention relates to a liquid crystal polyester multifilament. Specifically, the present invention relates to a liquid crystal polyester multifilament having a high strength and a high elastic modulus, which can be suitably used for general industrial materials, and has improved raw yarn strength utilization rate during high-order processing.

  Liquid crystalline polyester multifilament is made from liquid crystalline polyester polymer having a rigid molecular structure. In melt spinning, the molecular chains are highly oriented in the fiber axis direction, and further subjected to heat treatment at high temperature for a long time. It is known that the highest strength and elastic modulus are expressed among the obtained fibers. In addition, liquid crystal polyester fibers are known to have improved heat resistance and dimensional stability because the molecular weight increases and the melting point increases by heat treatment. Such liquid crystal polyester fibers are suitable for general industrial material applications, such as ropes, slings, fishing nets, nets, meshes, woven fabrics, fabrics, sheet materials, belts, tension members, various reinforcing cords, resin reinforcing fibers, and the like. Can be used.

  For such a liquid crystal polyester multifilament, a method for producing a pseudo monofilament yarn in which a plurality of filaments are integrated, a preparation step of preparing a plurality of filaments melt-spun from a heat-resistant thermoplastic liquid crystal polymer, A bundling step of bundling the plurality of filaments by twisting and / or forming a string to form a bundling body of the filaments, and the bundling body of the filaments in the cross section of the bundling body in a non-stretched state in contact with the filaments A heating step of heating the thermoplastic liquid crystal polymer to a temperature equal to or higher than the thermal deformation temperature of the thermoplastic liquid crystal polymer and fusing the contact surfaces of adjacent filaments together in a state where the portion and the non-contact portion are mixed inside the focusing body; A method of manufacturing a pseudo monofilament yarn provided has been proposed (see Patent Document 1). In addition, it suppresses the fusion between the single fibers constituting the multifilament, reduces defects caused by fusion in the solid phase polymerization of each single fiber, improves the uniformity in the longitudinal direction of the fiber, Liquid crystalline polyester multifilaments for splitting have also been proposed that are superior in the ability to pass through high-order processing of fibers, such as the textile process, and can dramatically improve production efficiency without the need for special equipment and equipment ( Patent Document 2).

WO2010 / 119756 publication JP2013-133575A

  However, in such a liquid crystal polyester multifilament having high strength and high elastic modulus, there is a problem that the raw yarn strength utilization rate is lowered when a high-order processed product is obtained. In general, each single fiber in the multifilament yarn is generally entangled in the longitudinal direction of the yarn, and the fibers are intertwined with each other, so-called entangled, so that the single fiber The linearity of the yarn is lost, and the strength factor of the raw yarn is reduced during the tensile test. In particular, in the case of a high-order processed product, the multifilament yarns are entangled in a complicated manner, so that the raw yarn strength utilization rate is further reduced, and sufficient product characteristics cannot be obtained. The decrease in the raw yarn strength utilization rate due to such entanglement between fibers is caused by the use of super fibers such as liquid crystal polyester multifilaments having a rigid molecular structure and highly oriented molecular chains in the fiber axis direction. Especially manifest. That is, when each single fiber is arranged linearly, the yarn strength is sufficiently exerted and the single fiber in the multifilament yarn is entangled although it is extremely resistant to pulling in the fiber axis direction. In many cases, when the linearity of the raw yarn is lost, the strength utilization rate of the raw yarn is significantly reduced as compared with the general-purpose fiber. As described above, the liquid crystalline polyester multifilament has dramatically improved mechanical properties due to heat treatment at a high temperature for a long time, whereas when heat-treated in a state where there are many entanglements of each single fiber in the multifilament yarn, As a result, partial fusion due to softening of the polymer occurs and the linearity of the fiber is reduced, and the fused part becomes a defect, so stress concentrates on the defective part during the tensile test, further reducing the strength utilization rate of the raw yarn Is triggered.

  In Patent Document 1, after twisting and / or stringing a multifilament yarn, the multifilament yarn is heat-treated under no tension, thereby mixing a fusion portion and a non-fusion portion in the multifilament yarn to form a pseudo monofilament. Although it is characterized by manufacturing, when such a method is adopted, each single fiber in the multifilament yarn is fused non-uniformly, so that a highly rigid multifilament yarn can be obtained. Since the fibers are intertwined while being intertwined, the linearity of each single fiber is reduced, and the strength utilization rate of the raw yarn is lowered when a high-order processed product is obtained.

  Moreover, in patent document 2, by controlling the winding conditions before winding (wind ratio, twill angle, distance between single fibers), the fusion between single fibers at the time of solid weight is suppressed, and the fiber separation property is excellent. Although a liquid crystal polyester multifilament for splitting can be obtained, when used as a multifilament, the individual filaments are not bundled and are easily separated, so that in the higher-order process, the talmi in the yarn is induced. The raw yarn strength utilization rate is low due to poor alignment.

  Therefore, the present invention has an object to solve such conventional problems, that is, to provide a liquid crystal polyester multifilament having high strength and high elastic modulus in which the raw yarn strength utilization rate at the time of high-order processing is improved. And

  In order to solve the above problems, the present invention has the following configuration. That is, the liquid crystal polyester multifilament is characterized in that the actual yarn width ratio X calculated from the ratio of the actual yarn width B to the theoretical yarn width A of the multifilament yarn is 20 to 70%.

  In the present invention, the multifilament yarns are heated without converging during melt spinning, and each single fiber forms a yarn form extending in a direction perpendicular to the longitudinal direction of the yarn, and is wound up. It is a method for producing the above-mentioned liquid crystalline polyester multifilament, characterized by performing phase polymerization.

  Furthermore, this invention is a high-order processed product which consists of said liquid crystalline polyester multifilament.

  Another aspect of the present invention is a rope or sling made of the above liquid crystal polyester multifilament.

  Yet another aspect of the present invention is a tension member comprising the above-mentioned liquid crystal polyester multifilament.

  Yet another aspect of the present invention is a fiber reinforced resin composition comprising the above liquid crystal polyester multifilament.

  In the liquid crystal polyester multifilament of the present invention, the actual yarn width ratio X calculated from the ratio of the actual yarn width B to the theoretical yarn width A of the multifilament yarn is 20 to 70%. Multifilament yarns are flattened without being rounded. Since the liquid crystal polyester multifilament having such a thread form maintains the linearity of each single fiber, the strength utilization rate of the raw yarn becomes higher when a high-order processed product is used, such as a high strength rope or sling. It can be suitably used for general industrial materials.

  The present invention is described in detail below.

  Although the manufacturing method of the liquid crystalline polyester multifilament of this invention is not limited at all as long as the liquid crystalline polyester multifilament prescribed | regulated by this invention is obtained, a preferable form is described below.

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

  Examples of the liquid crystal polyester used in the present invention include a polymer of aromatic oxycarboxylic acid (a), a polymer of aromatic dicarboxylic acid and aromatic diol, a polymer of aliphatic diol (b), (a) and (b ), And the like. Among them, a polymer composed only of an aromatic is preferable. Polymers composed only of aromatics exhibit excellent strength and elastic modulus when made into fibers. Moreover, conventionally well-known method can be used for the polymerization prescription of liquid crystalline polyester.

  Here, examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid (p-hydroxybenzoic acid and the like), hydroxynaphthoic acid and the like (6-hydroxy-2-naphthoic acid and the like), and alkyl, alkoxy and halogen substitution thereof. Examples include the body.

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

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

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

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

  In the present invention, a liquid crystal polyester composed of structural units (I), (II), (III), (IV) and (V) represented by the following chemical formula 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 properties at a spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, a relatively uniform fiber is obtained in the longitudinal direction, and has an appropriate crystallinity. Strength and elastic modulus can be increased.

  Furthermore, in the present invention, it is important to combine components composed of diols that are not bulky and have high linearity like the structural units (II) and (III). By combining these components, the molecular chains in the fiber have an ordered and less disturbed structure, and the crystallinity is not excessively increased and the interaction in the direction perpendicular to the fiber axis can be maintained. Thereby, in addition to high strength and elastic modulus, excellent wear resistance is also obtained.

  The above structural unit (I) is preferably 40 to 85 mol%, more preferably 65 to 80 mol%, still more preferably 68 to 75 mol%, based on the total of the structural units (I), (II) and (III). . 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% with respect to the total of the structural units (II) and (III). By setting it as such a range, since crystallinity does not become high too much and the interaction of a fiber axis perpendicular | vertical direction can be maintained, abrasion resistance can be improved.

  The structural unit (IV) is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, still more preferably 60 to 85 mol% with respect to 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 has a good spinning property at a spinning temperature set between the melting point of the polymer and the thermal decomposition temperature. A relatively uniform fiber is obtained.

  The total of the structural units (II) and (III) and the total of (IV) and (V) are preferably substantially equimolar. The term “substantially equimolar” as used herein means that equimolar amounts of dioxy units and dicarbonyl units constituting the main chain are present, and one of the terminal structural units may be unevenly distributed. It means that it is not necessary.

Particularly preferred ranges of the respective structural units of the liquid crystal polyester used in the present invention are as follows. In addition, the preferable range of each structural unit is a range when the sum total of structural unit (I), (II), (III), (IV) and (V) is 100 mol%. 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%

  The polystyrene equivalent weight average molecular weight (hereinafter, Mw) of the liquid crystalline polyester used in the present invention is preferably 30,000 or more, and more preferably 50,000 or more. By setting Mw to 30,000 or more, it is possible to increase the spinning property with an appropriate viscosity at the spinning temperature, and the higher the Mw, the higher the strength, elongation, and elastic modulus of the resulting fiber. Further, from the viewpoint of improving fluidity, Mw is preferably less than 250,000, and more preferably less than 150,000. In the present invention, Mw is a value determined by the method described in the examples.

  The melting point of the liquid crystalline polyester of the present invention is preferably in the range of 200 to 380 ° C., more preferably 250 to 350 ° C., more preferably 290 to 340 ° C. from the viewpoint of melt spinning and heat resistance. is there. In the present invention, the melting point is a value determined by the method described in the examples.

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

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

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

  Further, in the melt spinning of the liquid crystal polyester multifilament of the present invention, in order to reduce the energy cost and improve the productivity, a large number of base holes are perforated in one base. It is better to stabilize the behavior.

  In order to achieve this, it is preferable to reduce the diameter of the base hole and increase the land length (the length of the straight pipe portion equal to the diameter of the base hole). However, from the viewpoint of effectively preventing clogging of holes, the hole diameter is preferably 0.03 mm or more and 1.00 mm or less, more preferably 0.05 mm or more and 0.80 mm or less, and further preferably 0.08 mm or more and 0.60 mm or less. . From the viewpoint of effectively preventing an increase in pressure loss, the L / D defined by the quotient obtained by dividing the land length L by the hole diameter D is preferably 0.5 or more and 3.0 or less, preferably 0.8 or more. 5 or less is more preferable, 1.0 or more and 2.0 or less are still more preferable. In order to improve the productivity of multifilaments, the number of holes in one die is preferably 10 or more and 500 or less, more preferably 10 or more and 400 or less, and still more preferably 10 or more and 300 or less. In addition, it is preferable that the introduction hole located immediately above the die hole is a straight hole having a diameter of 5 times or more the diameter of the die hole in terms of not increasing pressure loss. It is preferable to taper the connection part between the introduction hole and the base hole in order to suppress abnormal stagnation. However, the length of the taper part should be less than twice the land length without increasing pressure loss and stabilizing the streamline. This is preferable.

  The polymer discharged from the base hole passes through a heat retaining region and a cooling region and solidifies, and then is taken up by a roller (godet roller) that rotates at a constant speed. If the heat retention region is excessively long, the yarn-forming property is deteriorated, so that it is preferably up to 400 mm from the base surface, more preferably up to 300 mm, and still more preferably up to 200 mm. In the heat retaining region, it is possible to increase the ambient temperature using a heating means, and the temperature range is preferably 100 ° C. or higher and 500 ° C. or lower, more preferably 200 ° C. or higher and 400 ° C. or lower. For the cooling, an inert gas, air, water vapor or the like can be used. However, it is preferable to use a parallel or annular air flow from the viewpoint of reducing the environmental load.

  The take-up speed is preferably 50 m / min or more, more preferably 300 m / min or more, and even more preferably 500 m / min or more for improving productivity. Since the liquid crystalline polyester used in the present invention has a suitable spinnability at the spinning temperature, the take-up speed can be increased. The upper limit is not particularly limited, but the liquid crystal polyester used in the present invention is about 3,000 m / min from the viewpoint of spinnability.

The spinning draft defined by the quotient obtained by dividing the take-up speed by the discharge linear speed is preferably 1 or more and 500 or less, more preferably 5 or more and 200 or less, and still more preferably 12 or more and 100 or less. Since the liquid crystalline polyester used in the present invention has suitable spinnability, the draft can be increased, which is advantageous in improving productivity. The discharge linear velocity (m / min) used in the calculation of the spinning draft is defined by the quotient obtained by dividing the discharge amount per single hole (m ³ / min) by the single hole cross-sectional area (m ² ). Since the value is a value and the take-up speed (m / min) is divided by the discharge linear speed, the spinning draft is a dimensionless number.

  In the present invention, in order to obtain the above spinning draft, it is preferable to set the polymer discharge rate per spinning pack as 10 to 2,000 g / min, and from 20 to 1,000 g / min from the viewpoint of improving the spinning performance and productivity. More preferably, it is more preferably set to 30 to 500 g / min. By spinning at a high discharge rate of 10 to 2,000 g / min, the productivity of the liquid crystal polyester is improved.

  Although winding can be made into a package such as cheese, parn, corn or the like using a normal winder, it is preferable to use cheese winding that can set the winding amount high.

  In the present invention, there is provided a liquid crystal polyester multifilament characterized in that the actual yarn width ratio X calculated from the ratio of the actual yarn width B to the theoretical yarn width A of the multifilament yarn as in the present invention is 20 to 70%. The most important point to obtain is to solid-phase polymerize the multifilament spun yarn without melting it during melt spinning.

  That is, in the present invention, as a result of earnestly examining the relationship between the yarn form of the liquid crystal polyester multifilament and the raw yarn strength utilization rate in the high-order processed product, the multifilament yarn is heated without being converged during melt spinning. It was found that a liquid crystal polyester multifilament having an actual yarn width ratio X of 20 to 70% was obtained, and that the strength utilization ratio of the raw yarn was increased when a high-order processed product was obtained.

  In melt spinning of liquid crystal polyester multifilament, the spinning filament is applied to the discharged yarn with an oiling roller or the like, the multifilament yarn is converged, taken up with a roller or the like, and then wound with a winder without drawing. It is common. In this way, by winding the multifilament spun yarn, the winding property is improved, and a winding package without collapse is obtained.

  On the other hand, in the present invention, the multifilament spun yarn discharged using a bar guide or the like is aligned in one direction before converging the multifilament spun yarn, and then heated while being pinched by a nip roller or the like. It has been found that a liquid crystal polyester multifilament having a film-like flat yarn form with little entanglement of each single fiber can be obtained. The one direction here means a direction perpendicular to the longitudinal direction of the multifilament spun yarn, and the single yarns in the multifilament spun yarn are aligned in a direction perpendicular to the longitudinal direction of the yarn. Thus, the spun yarn can be introduced into the nip roller while suppressing the entanglement between the single fibers. Here, the single yarns do not need to be arranged in parallel strictly, but may be arranged so as to be arranged substantially in parallel so as to satisfy the implementation width ratio defined in the present invention.

  That is, according to the present invention, the actual yarn width ratio X of the multifilament yarn can be controlled to 20 to 70%. As described above, the liquid crystalline polyester multifilament of the present invention having a film-like flat yarn form has been found to have a significantly higher raw yarn strength utilization rate when compared with the prior art when made into a high-order processed product. It was. This is because there is little entanglement of each single fiber in the liquid crystal polyester multifilament yarn, and each single fiber spreads in a direction perpendicular to the longitudinal direction of the yarn (so-called film-like flat yarn form). Since the linearity of each single fiber is maintained, it is considered that when a high-order processed product in which multifilament yarns are intertwined in a complicated manner, the raw yarn strength utilization rate can be improved.

  The method of heating the multifilament spun yarn without converging at the time of melt spinning is not limited at all, but as described above, the multifilament spun yarn discharged using a bar guide or the like is aligned in one direction. Then, it is preferable to heat while sandwiching with a nip roller or the like. A bar guide or the like may not be used as long as the discharged multifilament yarn can be introduced into a nip roller or the like without converging. Further, if the multifilament spun yarn spread in one direction can be heated, there is no problem even if it is heated not by the nip roller but by a non-contact heater.

  The actual yarn width ratio X of the multifilament yarn referred to in the present invention can be controlled by adjusting the entanglement state (convergence) of the single fibers when the multifilament yarn is aligned in one direction. The adjustment method of the entanglement state (sharvesting property) between the single fibers is not limited at all, but for example, by adjusting the shape of the guides and the surface friction resistance, the focusing property can be adjusted and the actual yarn width ratio X can be controlled. Is possible.

  The heating temperature is not limited as long as the multifilament yarn form can be fixed, but is preferably less than the melting point of the liquid crystal polyester resin to be used. In this invention, about 50 to 250 degreeC is preferable, 100 to 200 degreeC is more preferable, and 120 to 180 degreeC is still more preferable. If the heating temperature is too high, single fiber breakage, so-called fluff and spun yarn breakage occur frequently. Therefore, it is preferable that the heating temperature be low if the multifilament yarn form can be fixed. The actual yarn width ratio X of the multifilament yarn referred to in the present invention can also be controlled by adjusting the heating conditions (time and temperature) in heating the multifilament yarn. This is because the form fixing state of the multifilament yarns aligned in one direction can be controlled by adjusting the heating conditions.

  In this way, after heating the multifilament spun yarn without converging, there is no problem even if various oil agents are used using an oiling roller or the like in order to reduce the frictional resistance with the guide or the roller. .

  The liquid crystalline polyester multifilament of the present invention having a film-like flat thread shape obtained by melt spinning is preferably subjected to solid phase polymerization in order to further improve the strength and elastic modulus. Solid-phase polymerization can be processed into a package shape, a crushed shape, a tow shape (for example, on a metal net) or continuously as a thread between rollers, but the equipment can be simplified and produced. It is preferable to use a package shape from the viewpoint of improving the performance.

When solid-phase polymerization is performed in the form of a package, it is easy to fuse. Therefore, in order to prevent this, a fiber package having a winding density of 0.30 g / cm ³ or more when performing solid-phase polymerization is formed on the bobbin as a fiber package. It is preferred to form and solid phase polymerize it. Here, the winding density is calculated by Wf / Vf (g / cm ³ ) from the package occupied volume Vf (cm ³ ) and the fiber weight Wf (g) obtained from the package outer dimensions and the bobbin dimensions as the core material. Value. When the winding density is excessively small, the tension in the package is insufficient, so that the contact area between the fibers is increased and the fusion is increased. In addition, the package is collapsed and is preferably set to 0.30 g / cm ³ or more. more preferably to .40g / cm ³ or more and more preferably be 0.50 g / cm ³ or more. Further, the upper limit is not particularly limited, but if the winding density is excessively large, the adhesion between fibers in the inner layer of the package is increased and the fusion at the contact is increased, so that it is preferably 1.50 g / cm ³ or less. . In the present invention, the winding density is more preferably 0.30 to 1.00 g / cm ³ from the viewpoint of reducing fusion and preventing collapse.

  Such a winding density package has good production efficiency and simplifies the process. For example, it is possible to form a package having the above winding density by directly winding the liquid crystal polyester during melt spinning, thereby improving the production efficiency. Further, when adjusting the yarn weight at the time of solid phase polymerization, the package once wound by melt spinning can be rewound to form a package having the above winding density. In order to adjust the package shape and control the winding density, a contact roll or the like that is usually used is not used, the fiber package surface is wound in a non-contact state, or the melt spun raw yarn is directly passed through a speed control roll, It is also effective to wind with a winder controlled in speed. In these cases, in order to adjust the package shape, the winding speed is preferably 3000 m / min or less, particularly 2000 m / min or less. The lower limit is preferably 50 m / min or more from the viewpoint of productivity.

  The bobbin used to form the fiber package may be of any cylindrical shape, and when wound as a fiber package, it is attached to a winder and rotated to wind the fiber and form a package. To do. 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 solid-state polymerization can be efficiently performed. 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 felt made of organic fibers such as aramid fibers or metal fibers, 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 fiber weight of the fiber package may be any weight as long as the winding density falls within the range of the present invention, but is preferably 0.01 kg or more and 11 kg or less in consideration of productivity. The yarn length is preferably in the range of 10,000 m to 2 million m.

  In order to prevent fusion at the time of solid phase polymerization, it is a preferred embodiment to attach an oil agent to the fiber surface. The adhesion of these components may be performed between melt spinning and winding, but in order to increase the adhesion efficiency, it is performed at the time of rewinding, or a small amount is adhered by melt spinning and further added at the time of rewinding. Is preferred.

  The oil agent adhesion method may be guide oiling, but adhesion with a metal or ceramic kiss roll (oiling roll) is preferable in order to uniformly adhere to the fiber.

  As a component of the oil agent, it is better to have high heat resistance because it is not volatilized by high-temperature heat treatment in solid phase polymerization, and normal inorganic particles, fluorine compounds, siloxane compounds (dimethylpolysiloxane, diphenylpolysiloxane, methylphenylpolysiloxane, etc.) ) And mixtures thereof. Examples of normal inorganic particles in the present invention include minerals, metal hydroxides such as magnesium hydroxide, metal oxides such as silica and alumina, carbonates such as calcium carbonate and barium carbonate, calcium sulfate and barium sulfate, etc. In addition to the sulfate compound, carbon black and the like can be mentioned.

  These components may be solid-coated or directly coated with an oil agent, but emulsion coating is preferable for uniform coating while optimizing the coating amount, and water emulsion is particularly preferable from the viewpoint of safety. Therefore, it is desirable that the component be water-soluble or easily form a water emulsion. Among them, a mixed oil agent mainly composed of a siloxane-based compound water emulsion and silica or silicate added thereto is inactive under solid-state polymerization conditions. In addition to the anti-fusing effect in solid phase polymerization, it is also preferable because it shows an effect on slipperiness. When using a silicate, a phyllosilicate having a layered structure is particularly preferable. Examples of phyllosilicates include kaolinite, halloyite, serpentine, siliceous ore, smectite group, granite, talc, mica, etc. Among these, talc in consideration of availability Most preferably, mica is used.

  The amount of the oil agent attached to the fiber is preferably large in order to suppress fusion, and is preferably 0.5% by weight or more, more preferably 1.0% by weight or more when the entire fiber is 100% by weight. 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 that it is preferably 10.0% by weight or less, more preferably 8.0% by weight or less, and 6.0% by weight or less. Particularly preferred. In addition, the amount of oil agent adhesion 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.

The solid-state polymerization temperature is preferably such that the maximum attainment temperature is equal to or higher than the melting point (T _m1 ) -80 ° C. of the liquid crystal polyester fiber with _{respect to} the melting point (T _m1 ) of the liquid crystal polyester fiber subjected to solid phase polymerization. By setting the temperature close to the melting point, solid phase polymerization can proceed rapidly and the strength of the fiber can be improved. Moreover, it is preferable for the maximum temperature to be less than T _m1 in order to prevent fusion. Further, since the melting point of the liquid crystal polyester fiber increases with the progress of the solid phase polymerization, the solid phase polymerization temperature is increased to the melting point (T _m1 ) of the liquid crystal polyester filament used for the solid phase polymerization to about 100 ° C. according to the progress state of the solid phase polymerization. be able to. Increasing the solid-phase polymerization temperature stepwise or continuously with respect to time is more preferable because it can prevent fusion and increase the time efficiency of solid-phase polymerization.

  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 strength, elastic modulus and melting point of the fiber. The upper limit is not particularly limited, but the effect of increasing strength, elastic modulus, and melting point is saturated with the passage of time, so about 100 hours is sufficient, and in order to increase productivity, a short time is preferable, and about 50 hours is sufficient.

  The package after the solid phase polymerization is preferably rewound again to increase the winding density in order to increase the transport efficiency. At this time, when unwinding the fiber from the solid-phase polymerization package, the solid-phase polymerization package is rotated to prevent collapse of the solid-phase polymerization package due to unraveling and to suppress fibrillation when peeling a slight fusion. It is preferable that the yarn is unwound by so-called pre-winding, in which the yarn is unwound in the direction perpendicular to the rotation axis (fiber wrapping direction), and the solid-phase polymerization package is not freely rotated but is rotated by positive drive. This is preferable in that the yarn separation tension from the fiber can be reduced and fibrillation can be further suppressed.

  Here, in order to form a liquid crystal polyester multifilament package, it can be a package in the form of a pan, a drum, a cone, etc., but from the viewpoint of productivity, a drum winding that can secure a large amount of winding It is preferable to do.

  In addition, the liquid crystalline polyester fiber in the present invention is better to give the multifilament yarn a bundling property in order to increase the strength utilization rate and process passability when it is a high-order processed product. It is a preferred embodiment to apply an oil agent.

  The actual yarn width ratio X of the liquid crystal polyester multifilament of the present invention is essential to be 20 to 70%, more preferably 25 to 70%, and still more preferably 30 to 70%. When the actual yarn width ratio X is less than 20%, the single filaments in the multifilament yarn are entangled with each other, so that the straightness of each single fiber is not maintained, and the raw yarn is used in a high-order processed product. Powerful utilization rate is low. In addition, when the actual yarn width ratio X exceeds 70%, although the entanglement between the single fibers is small, the single fibers spread too much in the vertical direction with respect to the longitudinal direction of the yarn. It is likely to occur, and the raw yarn strength utilization rate is low when a high-order processed product is used. In other words, in the case of a high-order processed product, it is important to reduce the entanglement of each single fiber to such an extent that the converging property of the multifilament yarn is not impaired. Thus, when the actual yarn width ratio X is less than 20% or exceeds 70%, the present invention cannot be achieved.

  As in the present invention, the liquid crystal polyester multifilament having an actual yarn width ratio X of 20 to 70% is less entangled with each single fiber in the multifilament yarn, and each single fiber is perpendicular to the longitudinal direction of the yarn. By having a yarn shape that spreads in the direction, the straightness of each single fiber is maintained, and when the multi-filament yarn is intricately entangled with each other, it is possible to improve the raw yarn strength utilization rate. Furthermore, by setting the actual yarn width ratio X to 20 to 70% and having a film-like flat yarn form, gas diffusibility from each single fiber is improved and the polymerization reaction is promoted during solid phase polymerization. For this reason, variations in strong elongation and elastic modulus are reduced, and a liquid crystal polyester multifilament having uniform physical properties can be obtained. The actual yarn width ratio X indicates a value obtained by the method described in the examples.

  The actual yarn width variation in the longitudinal direction of the liquid crystalline polyester multifilament of the present invention is preferably 5 to 20%, more preferably 5 to 15%, and still more preferably 5 to 10%. . By setting the actual yarn width variation in the longitudinal direction of the yarn to 5 to 20%, the entangled state of the single fibers in the longitudinal direction of the yarn is uniform, and the linearity of each single fiber is also uniform at the same time. In the case of a high-order processed product in which strips are intertwined in a complicated manner, it is possible to improve the raw yarn strength utilization rate. Furthermore, the dispersion of the actual yarn width in the longitudinal direction of the yarn is 5 to 20%, and by having a uniform yarn shape in the longitudinal direction, the gas diffusibility from each single fiber is improved during the solid phase polymerization, and the polymerization reaction Because of this, the variation in strong elongation and elastic modulus is reduced, and a liquid crystal polyester multifilament having uniform physical properties can be obtained. The actual yarn width variation in the longitudinal direction of the yarn refers to a value obtained by the method described in the examples.

   The single fiber fineness of the liquid crystal polyester multifilament of the present invention is preferably 1 to 20 dtex. Moreover, it is more preferable that it is 1-15 dtex. By reducing the fineness of the single fiber from 1 to 20 dtex, it becomes possible to uniformly cool the inside of the single fiber after discharging, and it is easy not only to obtain a liquid crystal polyester multifilament having a stable fluff property and good fluff quality, but also heat treatment. The surface area of the fiber that sometimes comes into contact with the outside air increases, which is advantageous for high strength and high elasticity. Since the yarn of the liquid crystalline polyester multifilament of the present invention having a single fiber fineness of 1 to 20 dtex is flexible, it is excellent in high-order process passability, and when used in woven fabrics, the yarn filling rate is high. , Increase in density and improve storage. The single fiber fineness (dtex) referred to in the present invention is a quotient obtained by dividing the total fineness by the number of single fibers.

   The number of single fibers of the liquid crystal polyester multifilament of the present invention is preferably 10 to 500, more preferably 10 to 400, and even more preferably 10 to 300. By setting the number of single fibers to 10 to 500, the productivity of multifilaments can be improved, and the surface area of the fibers that come into contact with the outside air during heat treatment increases, so the solid-state polymerization reaction is promoted, resulting in variations in strength and elastic modulus. A liquid crystal polyester multifilament having reduced and uniform physical properties can be obtained. In addition, there is no problem even if the sample obtained by spinning is divided or combined into a liquid crystal polyester multifilament having 10 to 500 single fibers. In addition, the number of single fibers points out the value calculated | required by the method described in the Example.

  The total fineness of the liquid crystal polyester multifilament of the present invention is preferably 100 to 3,000 dtex, more preferably 150 to 2,500 dtex, and further preferably 200 to 2000 dtex. By setting it as 100-3,000 dtex, it is suitable for industrial material use with high production efficiency and a very large amount of raw yarn used. In addition, there is no problem even if the sample obtained by spinning is divided or combined into a liquid crystal polyester multifilament having a total fineness of 100 to 3,000 dtex. The total fineness refers to a value obtained by the method described in the examples.

  The strength after solid phase polymerization of the liquid crystalline polyester multifilament of the present invention is preferably 13.0 cN / dtex or more, more preferably 15.0 cN / dtex or more, and further preferably 17.0 cN / dtex or more. When the strength is 13.0 cN / dtex or more, it is suitable for industrial materials that require high strength and light weight. The upper limit of the strength is not particularly limited, but the upper limit that can be achieved in the present invention is about 30.0 cN / dtex. In addition, the strength said by this invention points out the tensile strength by the strong elongation and elastic modulus measurement described in the Example.

   The elongation after solid phase polymerization of the liquid crystalline polyester multifilament of the present invention is preferably 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less. Since the elongation is 5.0% or less, it is difficult to stretch when subjected to stress from the outside, and can be suitably used without causing a dimensional change when lifting a heavy object. The lower limit of the elongation is not particularly limited, but the lower limit that can be achieved in the present invention is about 1.0%. In addition, the elongation said by this invention points out the breaking elongation by the strong elongation and elastic modulus measurement described in the Example.

  The elastic modulus after solid phase polymerization of the liquid crystalline polyester multifilament of the present invention is preferably 500 cN / dtex or more, more preferably 700 cN / dtex or more, and still more preferably 900 cN / dtex or more. When the elastic modulus is 500 cN / dtex or more, the dimensional change when subjected to stress is small, which is suitable for industrial materials. 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 1,500 cN / dtex elastic modulus. In addition, the elasticity modulus said by this invention refers to the elasticity modulus by the strong elongation and the elasticity modulus measurement described in the Example.

  The strength variation and elongation variation of the liquid crystal polyester multifilament of the present invention are preferably 0.1 to 5.5%, more preferably 0.1 to 3.5%, More preferably, it is -2.5%. Since the liquid crystalline polyester multifilament of the present invention has excellent physical property stability with a variation in strength of 0.1 to 5.5%, when used as a product, the physical property utilization rate of the raw yarn is high, and physical properties such as product strength. Improvement can be achieved. In addition, the strength elongation variation indicates a value obtained by the method described in the examples.

  The liquid crystal polyester multifilament of the present invention thus obtained has an actual yarn width ratio X calculated from the ratio of the actual yarn width B to the theoretical yarn width A of the multifilament yarn, and is 20 to 70%. There is little entanglement of the fiber, and the multifilament yarn becomes flat without being rounded. In the liquid crystal polyester multifilament having such a form, the linearity of each single fiber is maintained, so that the strength utilization rate of the raw yarn is increased when a high-order processed product is obtained. As described above, the liquid crystal polyester multifilaments having high strength, high elastic modulus, heat resistance, dimensional stability, chemical resistance, and low moisture absorption properties, in which the shape of the multifilament yarn is controlled, are suitable for general industrial material applications. Can be used. Examples of general industrial material applications include ropes, slings, fishing nets, nets, meshes, woven fabrics, fabrics, sheet-like materials, belts, tension members, civil engineering / building materials, sports materials, protective materials, rubber reinforcing materials, various reinforcing materials Examples thereof include cords, resin reinforcing fiber materials, electrical materials, acoustic materials, and paper.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this. In addition, the definition of the characteristics used in the specification text and the examples, and the measurement and calculation methods of each physical property are shown below.

(1) Melting point After observation of the endothermic peak temperature (T _m1 ) observed when measuring the temperature rise condition from 50 ° C. to 20 ° C./min in differential calorimetry performed with a differential scanning calorimeter (DSC2920 manufactured by TA 1n instruments). After maintaining at a temperature of about T _m1 + 20 ° C. for 5 minutes, the temperature is lowered to 50 ° C. at a temperature lowering rate of 20 ° C./min, and the endothermic peak temperature ( T _m2 ) was taken as the melting point. The same operation was performed twice, and the average value of the two times was defined as the melting point T _m2 (° C.) of the liquid crystal polyester.

(2) 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 dissolved in a mixed solvent so that the concentration of liquid crystal polyester was 0.05% by weight to prepare a sample for GPC measurement. It measured using the GPC measuring apparatus made, and calculated | required Mw by polystyrene conversion. The same operation was performed twice, and the average value of the two times was defined as the weight average molecular weight (Mw).
Column: Shodex K-806M 2 pieces, K-802 1 piece Detector: Differential refractive index detector RI (8020 type)
Temperature: 23 ± 2 ° C
Flow rate: 0.8 mL / min Injection volume: 300 μL

(3) Moisture content It was measured by a coulometric titration method using a Karl Fischer moisture meter (AQ-2100) manufactured by Hiranuma Sangyo Co., Ltd. The average value of 3 trials was used.

(4) Oil agent concentration When the weight of the solution in which the oil agent is dispersed is W0 and the weight of the oil agent is W1, the product obtained by multiplying the quotient obtained by dividing W1 by W0 by 100 is the oil agent concentration (% by weight).

(5) Oil agent adhesion amount After measuring 100 m of fibers with a measuring instrument and measuring the weight, the casserole was immersed in 100 ml of water and washed for 1 hour using an ultrasonic cleaner. The casket after ultrasonic cleaning was dried and weighed, and the product obtained by multiplying the quotient obtained by dividing the difference between the weight before washing and the weight after washing by the weight before washing was 100 as the oil agent adhesion amount (% by weight).

(6) Total fineness According to JIS L1013 (2010) 8.3.1 A method, the positive fineness was measured at a predetermined load of 0.045 cN / dtex to obtain the total fineness (dtex).

(7) Number of single fibers Calculated by the method of JIS L1013 (2010) 8.4.

(8) Single fiber fineness The value obtained by dividing the total fineness by the number of single fibers was defined as the single fiber fineness (dtex).

(9) Strong elongation and elastic modulus of the spinning yarn Measured under constant speed elongation conditions shown in JIS L1013 (2010) 8.5.1 standard time test. The sample was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., the gripping interval (measurement test length) was 250 mm, and the tensile speed was 50 mm / min. The strength and elongation were the stress and elongation at break, and the elastic modulus was calculated from the maximum slope of the stress and elongation graph in the tensile test.

(10) Strength and elasticity of multifilament yarn subjected to solid-phase polymerization Measured under constant speed elongation conditions shown in JIS L1013 (2010) 8.5.1 standard time test. The sample was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., the gripping interval (measurement test length) was 250 mm, and the tensile speed was 50 mm / min. The strength and elongation were the stress and elongation at break, and the elastic modulus was calculated from the maximum slope of the stress and elongation graph in the tensile test.

Further, sampling, strength, elongation, elastic modulus, and calculation of strong elongation variation (CV%) were performed as follows. For the product package, every time the multifilament yarn is unwound 1000 m in the longitudinal direction of the fiber, the tenacity is measured 10 times and averaged to obtain the strong extensibility (hereinafter referred to as the strong extensibility and elastic modulus every 1000 m). The operation is performed over the entire package. The average value (a) is obtained for the strong elongation and elastic modulus every 1000 m thus obtained, and are defined as the strong elongation and elastic modulus. Further, using the average value (a) and standard deviation (σ) of the strength and elongation, the strength and elongation variation (CV%) in the longitudinal direction of the product package were calculated from the following formula.
Strength and elongation variation (CV%) = (σ / a) × 100

(11) Specific gravity As the specific gravity of the liquid crystal polyester multifilament, a specific gravity measuring machine (SGM300P manufactured by Shimadzu Corporation) was used, and an average value of 5 times of execution was adopted.

(12) Theoretical yarn width A of multifilament yarn
The yarn width of the multifilament yarn when the single fibers assumed to have a perfect circular cross section are arranged on a plane without overlapping each other and without any gap between them is defined as a theoretical yarn width A. The theoretical yarn width A was defined by the following equation using the theoretical single fiber diameter L (μm) and the number of single fibers F (main).
Theoretical yarn width A (μm) = theoretical single fiber diameter L (μm) × number of single fibers F (book)

Here, the theoretical single fiber diameter L is calculated from the following equation using the total fineness D (dtex), the number of single fibers F (line), the specific gravity d (g / cm 3), and the circumferential ratio π of the liquid crystal polyester multifilament. Calculated.
Theoretical single fiber diameter L (μm) = {(4D / F) / (d × 10 ⁶ × π)} ^0.5 × 10 ⁴

(13) Actual yarn width B and actual yarn width variation CV of multifilament yarn (%)
For the multifilament yarn, the actual yarn width B (μm) was defined as the yarn width in the direction perpendicular to the longitudinal direction of the yarn. The actual yarn width B is an average value of a total of 10 measurement values obtained by sampling a multifilament yarn 1100 mm, measuring the yarn width every 100 mm, excluding both ends. The actual yarn width variation (CV%) was calculated from the following equation using the average value a of 10 measured values and the standard deviation σ. In addition, the yarn width here means the yarn width in the direction perpendicular to the longitudinal direction of the yarn when the multifilament yarn is allowed to stand on a flat surface without loosening. When the yarn was film-like as in the present invention, the maximum yarn width in the yarn width perpendicular to the longitudinal direction of the yarn was measured as the actual yarn width B.
Actual yarn width variation (CV%) = (σ / a) × 100

(14) Multifilament yarn actual yarn width ratio X
The ratio of the actual yarn width B (μm) of the multifilament yarn to the theoretical yarn width A (μm) of the multifilament yarn was defined as the actual yarn width ratio X, and was calculated by the following formula.
Actual yarn width ratio X (%) = (B / A) × 100

(15) Suitability for high-order processed products Suitability for high-order processed products was evaluated by calculating the strength retention after twisting of the obtained liquid crystal polyester multifilament. The strength retention ratio X was calculated from the following formula from the raw yarn strength Y (N) after twisting with the twist coefficient K (-) being 80, and the raw yarn strength Z (N) before twisting. The twist coefficient K is a value obtained by T = K × (100 ÷ D ^ 0.5) using the number of twists T (turns / m) and the total fineness D (dtex) of the multifilament. When the strength retention ratio X is 70 to 95%, the suitability for high-order processed products is “◎”, and when the strength retention ratio X is 50 to 70%, the suitability for high-order processed products is “◯”. When the rate X was 30 to 50%, the suitability for high-order processed products was “Δ”, and when the strength retention rate X was 0 to 30%, the suitability for high-order processed products was “x”.
Strength retention X (%) = (Y / Z) × 100

  Hereinafter, the present invention will be described specifically by way of examples.

[Example 1]
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 157 parts by weight of isophthalic acid, 292 parts by weight of terephthalic acid, 89 parts by weight of hydroquinone Then, 1433 parts by weight of acetic anhydride (1.08 equivalent of the total phenolic hydroxyl groups) was added, and the temperature was raised from room temperature to 145 ° C. over 30 minutes with stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 330 degreeC in 4 hours. The polymerization temperature was maintained at 330 ° C., the pressure was reduced to 1.0 mmHg (133 Pa) in 1.5 hours, and the reaction was continued for another 20 minutes. When the predetermined torque was reached, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm ² (0.1 MPa), the polymer was discharged to a strand through a base having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.

  This liquid crystal polyester is composed of 54 mol% of p-hydroxybenzoic acid units, 16 mol% of 4,4′-dihydroxybiphenyl units, 8 mol% of isophthalic acid units, 15 mol% of terephthalic acid units, and 7 mol% of hydroquinone units. The melting point was 318 ° C., and the melt viscosity measured at a temperature of 328 ° C. and a shear rate of 1,000 / sec using a Koka flow tester was 16 Pa · sec. Moreover, Mw was 91,000.

  Using this liquid crystal polyester, vacuum drying was performed at 120 ° C. for 12 hours to remove moisture and oligomers. The water content of the liquid crystal polyester at this time was 50 ppm. The dried liquid crystal polyester was melt-extruded with a single-screw extruder (heater temperature 290 to 340 ° C.), and the polymer was supplied to the spin pack while being measured with a gear pump. The spinning temperature from the extruder outlet to the spinning pack at this time was 335 ° C. In the spinning pack, the polymer is filtered using a metal nonwoven fabric filter having a filtration accuracy of 15 μm, and the discharge amount is 37.5 g / min (0.00 per single hole) from a die having 75 holes having a hole diameter of 0.13 mm and a land length of 0.26 mm. The polymer was discharged at 50 g / min).

  Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 150 ° C. while sandwiching the yarn. . The yarn after heating had a film-like flat yarn form with little entanglement of each single fiber. After heating with a nip roller, an oil agent (polydimethylsiloxane (a water emulsion of 5.0% by weight of SH200-350cSt manufactured by Toray Dow Corning Co., Ltd.) using an oiling roller) is attached to both 75 filaments and 1,000 m. Taken with a Nelson roller / min. The spinning draft at this time is 32.7. Moreover, the oil agent adhesion amount was 1.5%. The yarn taken up by the Nelson roller was wound into a cheese shape using a feather traverse type winder directly through a dancer arm. The spinnability by melt spinning was good, and a liquid crystal polyester multifilament having a total fineness of 375 dtex and a single fiber fineness of 5 dtex could be stably spun without breaking the yarn, and a spinning yarn of 4.0 kg volume package was obtained.

The fiber is unwound in the longitudinal direction (perpendicular to the fiber circulation direction) from this spun fiber package and is 400 m / min by a winder (SSP-WV8P type precision winder manufactured by Kozu Manufacturing Co., Ltd.) with a constant speed. I rolled it back. A stainless steel bobbin was used as the core material for rewinding, the tension during rewinding was 0.005 cN / dtex, the winding density was 0.50 g / cm ^3, and the winding amount was 4.0 kg. Further, the package shape was a taper end winding with a taper angle of 65 °.

  The rewinded sample having a total fineness of 375 dtex and a single fiber fineness of 5 dtex thus obtained was heated from room temperature to 240 ° C using a closed oven, held at 240 ° C for 3 hours, and then heated to 290 ° C. Furthermore, solid state polymerization was performed under the condition of maintaining at 290 ° C. for 20 hours. The atmosphere was supplied with dehumidified nitrogen at a flow rate of 100 L / min, and exhausted from the exhaust port so that the inside of the chamber was not pressurized.

  The solid-phase polymerization package thus obtained was attached to a feeding device that can be rotated by an inverter motor, unwound while feeding the fibers in the transverse direction (fiber circumferential direction) at 200 m / min, and wound around the product package with a winder. However, the yarn could be unwound almost without resistance and no yarn breakage occurred. The fiber properties are as shown in Table 1. The liquid crystal polyester multifilament yarn of the present invention obtained in Example 1 has an actual yarn width ratio of 42%, an actual yarn width variation of 11%, a strength variation of 1.8%, and an elongation variation of 1.7%. Yes, each filament in the multifilament yarn has little entanglement, and each filament has a film-like flat yarn shape that spreads in the direction perpendicular to the longitudinal direction of the yarn. In some cases, the raw yarn strength utilization rate was high, and it could be suitably used for general industrial materials.

[Example 2]
The same method as in Example 1 except that the spun yarn of liquid crystal polyester multifilament cooled and solidified at room temperature immediately after discharge was introduced into the nip roller in one direction without being focused using a roller guide. A liquid crystal polyester multifilament was obtained.

[Example 3]
Liquid crystal polyester multifilament spun yarn that has been cooled and solidified at room temperature immediately after discharge is introduced into a nip roller in one direction without being converged using a bar guide, and 150 yarns are fed using a non-contact heater. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that it was heated at ° C.

[Example 4]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge were aligned in one direction without being converged using a bar guide, introduced into a nip roller, and heated at 50 ° C. while sandwiching the yarn. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Example 5]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 100 ° C. while sandwiching the yarn. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Example 6]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 200 ° C. while sandwiching the yarns. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Example 7]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 250 ° C. while sandwiching the yarns. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Example 8]
At the time of melt spinning, a spinning pack having 8 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm was used, the pack discharge rate was changed to 4.0 g / min, the number of single fibers was 8 filaments, and the total fineness was 40 dtex. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that.

[Example 9]
At the time of melt spinning, a spinning pack having 300 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm was used, the pack discharge rate was changed to 75.0 g / min, and the take-up speed was changed to 500 m / min. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that 300 filaments and the total fineness were 1500 dtex.

[Example 10]
At the time of melt spinning, a spinning pack having 720 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm was used, the pack discharge rate was changed to 180.0 g / min, and the take-up speed was changed to 500 m / min. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that 720 filaments and the total fineness were 3600 dtex.

[Example 11]
At the time of melt spinning, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the pack discharge rate was changed to 11.3 g / min and the total fineness was 113 dtex.

[Example 12]
At the time of melt spinning, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the pack discharge rate was changed to 112.5 g / min, the take-up speed was changed to 500 m / min, and the total fineness was 2250 dtex.

[Example 13]
A liquid crystal polyester was prepared in the same manner as in Example 1 except that a liquid crystal polyester resin comprising 73 mol% of p-hydroxybenzoic acid units and 27 mol% of 6-hydroxy-2-naphthoic acid units was used as the liquid crystal polyester resin. A multifilament was obtained.

  The fiber properties of Examples 1 to 13 are shown in Table 1.

[Comparative Example 1]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 40 ° C. while sandwiching the yarn. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Comparative Example 2]
Liquid crystal polyester multifilament spun yarns cooled and solidified at room temperature immediately after discharge are aligned in one direction using a bar guide and introduced into a nip roller, and heated at 320 ° C. while sandwiching the yarn. Except for this, a liquid crystal polyester multifilament was obtained in the same manner as in Example 1.

[Comparative Example 3]
Liquid crystal polyester multifilaments were produced in the same manner as in Example 1 except that the spun yarns of liquid crystal polyester multifilaments cooled and solidified at room temperature immediately after discharge were converged and introduced into a nip roller without using a bar guide. Got.

[Comparative Example 4]
The multifilament yarn is prepared by aligning the spun yarn of the liquid crystal polyester multifilament, which has been cooled and solidified at room temperature immediately after discharge, in one direction without converging using a bar guide, and introducing it into an unheated first stage nip roller. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the shape of the strip was expanded and fixed in advance, and further introduced into the second stage nip roller and heated at 150 ° C.
The fiber properties of Comparative Examples 1 to 4 are shown in Table 2.

  In the table, * 1 is p-hydroxybenzoic acid unit (54 mol%), 4,4'-dihydroxybiphenyl unit (16 mol%), isophthalic acid unit (8 mol%), terephthalic acid unit (15 mol%), hydroquinone unit. (* 2) in the table indicates a liquid crystal polyester resin composed of p-hydroxybenzoic acid units (73 mol%) and 6-hydroxy-2-naphthoic acid units (27 mol%).

  As is clear from Examples 1 to 13 in Table 1, the multifilament spinning yarn discharged using a bar guide or the like was aligned in one direction before the multifilament spinning yarn was converged during melt spinning. Thereafter, it is understood that by heating while sandwiching with a nip roller or the like, a liquid crystal polyester multifilament having a film-like and flat thread form can be obtained with little entanglement of each single fiber. In this way, the liquid crystal polyester multifilament of the present invention having a film-like flat yarn form, in which the actual yarn width ratio X of the multifilament yarn is controlled to 20 to 70%, is a high-order processed product. Compared with the prior art, the raw yarn strength utilization rate was significantly higher, and it could be used suitably for general industrial materials.

  On the other hand, as is clear from Comparative Examples 1 to 4 in Table 2, when the multifilament spun yarn aligned in one direction is heated at 40 ° C. or 320 ° C. during melt spinning, The yarn width ratio X was less than 20%, and the yarn was rounded. The same applies to Comparative Example 3 in which the multifilaments are focused and heated without using the guide. In this way, when the actual yarn width ratio X is less than 20%, each single fiber is intertwined in a complicated manner, so that the linearity of each single fiber is lost, and the high-strength yarn is used when making a high-order processed product. The rate was extremely low, and it was not at a level that could be used for general industrial materials that required high strength and high elastic modulus. On the other hand, using a bar guide, it is aligned in one direction and introduced into an unheated first-stage nip roller to expand and fix the shape of the multifilament spinning yarn in advance. In Comparative Example 4, which was introduced into the nip roller and heated at 150 ° C., the actual yarn width ratio X exceeded 70%, and the entanglement of each single fiber in the multifilament yarn could be suppressed, but each single fiber was the length of the yarn. Since it spreads too much in a direction perpendicular to the direction, it is easy to cause the single fiber to become talmi, and the strength utilization rate of the raw yarn was lowered when a high-order processed product was obtained. As described above, the present invention cannot be achieved when the actual yarn width ratio X is less than 20% or exceeds 70%.

  In the liquid crystal polyester multifilament of the present invention, since the actual yarn width ratio X is 20 to 70%, the entanglement of each single fiber is small, and the multifilament yarn becomes flat without being rounded. Since the liquid crystal polyester multifilament having such a yarn form maintains the linearity of each single fiber, the strength utilization rate of the raw yarn is high when it is a high-order processed product in which multifilament yarns are intertwined in a complex manner. Therefore, it can be suitably used for general industrial material applications such as high-strength ropes and slings.

Claims (11)

A liquid crystal polyester multifilament, wherein an actual yarn width ratio X calculated from a ratio of an actual yarn width B to a theoretical yarn width A of the multifilament yarn is 20 to 70%.   The liquid crystal polyester multifilament according to claim 1, wherein the actual yarn width variation in the longitudinal direction of the yarn is 5 to 20%. The liquid crystalline polyester multifilament according to claim 1 or 2, wherein the number of single fibers is 10 to 500. The liquid crystal polyester multifilament according to any one of claims 1 to 3, wherein the total fineness is 100 to 3000 dex. The liquid crystal polyester multifilament according to any one of claims 1 to 4, wherein the liquid crystal polyester is composed of the following structural units (I), (II), (III), (IV) and (V). .

  The proportion of the structural unit (I) is 40 to 85 mol% with respect to the total of the structural units (I), (II) and (III), and the proportion of the structural unit (II) is structural units (II) and (III) The liquid crystal polyester multi-layer according to claim 5, wherein the proportion of the structural unit (IV) is 40 to 95 mol% with respect to the total of the structural units (IV) and (V). filament.   Heating without converging the multifilament yarn during melt spinning, forming a yarn form in which each single fiber spreads in a direction perpendicular to the longitudinal direction of the yarn and winding it, followed by solid-phase polymerization The method for producing a liquid crystal polyester multifilament according to claim 1.   A high-order processed product comprising the liquid crystalline polyester multifilament according to any one of claims 1 to 6.   A rope or sling comprising the liquid crystal polyester multifilament according to any one of claims 1 to 6.   A tension member comprising the liquid crystal polyester multifilament according to any one of claims 1 to 6.   A fiber-reinforced resin composition comprising the liquid crystal polyester multifilament according to claim 1.