JP2018040078A - Liquid crystal polyester multifilament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal polyester multifilament that can express a significantly higher product strength as compared with the conventional art, when made into a high-order processed product.SOLUTION: A liquid crystal polyester multifilament has a knot strength and a loop strength each of which is 7.0-12.0 cN/dtex.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 that can be suitably used for general industrial materials such as slings and nets.

  Liquid crystalline polyester fiber is made from liquid crystalline polyester polymer having a rigid molecular structure. In melt spinning, molecular chains are highly oriented in the fiber axis direction, and heat treatment is performed at high temperature for a long time, resulting in melt spinning. 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.

JP 2006-336147 A JP 7-243128 A

  However, the above-mentioned liquid crystalline polyester fiber shows high strength in the fiber axis direction, but is weak against the force in the direction perpendicular to the fiber axis and easily buckles against bending, so it can be used in high-order processed products such as slings and nets. When it was used, the strength of the raw yarn was not sufficiently exhibited, and the product strength was liable to decrease.

  In order to solve such a problem, Patent Document 1 prevents the sticking of single yarns during heat treatment by applying inorganic particles to the fiber surface, and a melt-anisotropic aromatic polyester fiber that is supple and has high knot strength. Proposed. However, even if sticking between single yarns is prevented by this method, the rigidity of the single yarn itself is not improved, and it does not lead to a significant improvement in the stiffness of the fiber. The strength of the raw yarn was not fully exhibited, and sufficient product strength could not be obtained.

Further, in Patent Document 2, the core component is a melt anisotropic aromatic polyester, and the sheath component is composed of a sea component made of a flexible thermoplastic polymer and an island component made of a melt anisotropic aromatic polyester. A core-sheath composite fiber having a high knot strength has been proposed. However, this method only improves the rigidity of the polymer disposed on the fiber surface, and the rigidity of the core polymer occupying 50% or more of the fiber cross-sectional area is not improved. The strength of high-order processed products was not enough.
Thus, in the prior art, liquid crystal polyester multifilaments exhibiting high product strength when obtained as a high-order processed product have not been obtained.

  The present invention has been intensively studied against the background of the above-described circumstances, and a liquid crystal polyester multifilament that can exhibit a significantly higher product strength than the prior art when it is a high-order processed product. It is to provide.

  In order to solve the above problems, the present invention has the following configuration.

  (1) A liquid crystal polyester multifilament having hook strength and knot strength of 7.0 to 12.0 cN / dtex, respectively.

  (2) The liquid crystal polyester multifilament according to (1), wherein the strength is 15.0 cN / dtex or more.

  (3) The liquid crystal polyester multifilament according to (1) or (2), wherein the strength is 22.5 cN / dtex or more.

  (4) The liquid crystalline polyester multifilament according to (1) to (3), wherein the liquid crystalline polyester comprises structural units (I), (II), (III), (IV) and (V) represented by the following chemical formula .

  (5) The structural unit (I) is 40 to 85 mol% with respect to the total of the structural units (I), (II) and (III), and the structural unit (II) is the structural units (II) and (III). The structural unit (IV) is 40 to 95 mol% with respect to the total of the structural units (IV) and (V), and is 60 to 90 mol% with respect to the total of (1) to (4) Liquid crystal polyester multifilament.

  (6) The liquid crystalline polyester according to any one of (1) to (5), wherein when the package is unwound after solid phase polymerization, it is wound while being bent in at least four directions using a bearing roller. Multifilament manufacturing method.

  (7) A high-order processed product comprising the liquid crystal polyester multifilament according to any one of (1) to (5).

  (8) A rope or sling comprising the liquid crystal polyester multifilament according to any one of (1) to (5).

  (9) A net comprising the liquid crystal polyester multifilament according to any one of (1) to (5).

  (10) A tension member comprising the liquid crystal polyester multifilament according to any one of (1) to (5).

  (11) A fiber-reinforced resin composition comprising the liquid crystal polyester multifilament according to any one of (1) to (5).

  Since the liquid crystalline polyester multifilament of the present invention can exhibit high product strength when it is a high-order processed product, it can be suitably used for general industrial materials such as slings and nets.

  Hereinafter, the liquid crystal polyester multifilament of the present invention and the production method thereof will be described in detail.

  In addition, 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 crystal polyester on a hot stage, heating and heating in a nitrogen atmosphere, and observing the presence or absence of 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 monomer 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, Liquid crystalline polyester in which a 4,4′-dihydroxybiphenyl component, an isophthalic acid component and / or a terephthalic acid component are copolymerized, a p-hydroxybenzoic acid component, a 4,4′-dihydroxybiphenyl component, an isophthalic acid component, and a terephthalic acid component Examples thereof include liquid crystal polyester in which a hydroquinone component is 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 this invention, it is preferable to combine the component which consists of diol which is not bulky like the structural units (II) and (III) and has high linearity. 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 there may be cases where one of the terminal structural units is unevenly distributed. It means you may.

  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 addition, Mw said by this invention is taken as the value calculated | required by the method of an Example description.

  The melting point of the liquid crystalline polyester used in 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. It is. 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.

  In the liquid crystal polyester used in the present invention, various metal oxides, kaolin, silica and other inorganic materials, colorants, matting agents, flame retardants, antioxidants, ultraviolet absorbers, as long as the effects of the present invention are not impaired. A small amount of additives such as an infrared absorber, a crystal nucleating agent, a fluorescent brightening agent, a terminal group blocking agent, and a compatibilizing agent may be contained.

  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 cap hole and increase the land length (the length of the straight pipe portion of the cap 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 mouthpiece hole passes through the heat retaining region and the cooling region, solidifies into a filament, and is then 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.

The winding can be made into a package such as cheese, parn, corn or the like using a normal winder, but is preferably a cheese-wrapped package in which the winding amount can be set high.
In melt spinning of liquid crystal polyester multifilament, it is common to condense the multifilament by applying a spinning oil to the discharged yarn with an oiling roller, etc., take it up with a roller, etc., and then wind it with a winder without stretching. It is. In this way, by winding the multifilament spun yarn, the winding property is improved, and a package without unwinding is obtained.

  In the liquid crystal polyester multifilament, it is preferable to perform solid phase polymerization after melt spinning to obtain a filament.

When solid-phase polymerization is performed in the form of a package, it is easy to fuse. To prevent this, a package having a winding density of 0.30 g / cm ³ or more is formed on a bobbin, and this can be solid-phase polymerized. preferable. 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.

  A package having such a winding density has good processability and simplification of the process. For example, it is possible to form a package having the above-mentioned winding density by directly winding it after melt spinning of the liquid crystalline polyester, and the process passability can be improved. 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, the contact surface or the like that is usually used is not used, the surface of the package is wound in a non-contact state, and the melt spun raw yarn is directly passed through the speed control roll. It is also effective to wind with a controlled winder. 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 for forming the package may be of any cylindrical shape, and when wound as a package, the bobbin is attached to a winder and rotated to wind the fiber to form a package. In solid phase polymerization, the package can be processed integrally with the bobbin, but only the bobbin can be extracted from the 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. When the bobbin is removed from the package for processing, it is preferable to attach a skin to the outer surface of the bobbin. In either case, it is preferable that a cushion material is wound around the outer surface of the bobbin, and a liquid crystal polyester melt-spun filament 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 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 surface of the filament. 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 at the time of melt spinning and further added at the time of rewinding. It is preferable to do.

  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 oil agent 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.

The solid phase polymerization temperature is preferably the melting point (T _m1 ) -80 ° C. or higher of the liquid crystal polyester filament with respect to the melting point (T _m1 ) of the liquid crystal polyester filament 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 filament increases with the progress of the solid phase polymerization, the solid phase polymerization temperature is raised to about the melting point (T _m1 ) + 100 ° C. of the liquid crystal polyester filament used for the solid phase polymerization 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 the strength, elastic modulus, and melting point is saturated with the passage of time, so about 100 hours is sufficient, and a short time is preferable for improving productivity, and there is no problem even for about 50 hours.

  The package after solid phase polymerization is preferably rewound again to increase the winding density in order to increase the transport efficiency. At this time, when the filament is unwound from the solid-state polymerization package, the solid-state polymerization package is used to prevent collapse of the solid-state 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 side take-up, in which the yarn is unwound in the direction perpendicular to the rotation axis (fiber turning direction) while being rotated. Further, it is preferable that the solid-phase polymerization package is rotated not by free rotation but by positive driving in that the yarn separation tension from the package can be reduced and fibrillation can be further suppressed.

  A method for obtaining a liquid crystal polyester multifilament having a knot strength and a hook strength of 7.0 to 12.0 cN / dtex as in the present invention is not limited at all. For example, the filament is unwound from a package in which solid phase polymerization is completed. There is a method of bending in a plurality of directions. The direction here refers to a direction indicated by a range of 0 to 360 ° in a plane perpendicular to the longitudinal direction of the multifilament after unraveling, and a direction bent first and a direction bent thereafter are formed. The angle is defined as the azimuth angle (therefore, the azimuth angle in the first bent direction is 0 °).

  That is, in the present invention, as a result of earnest examination of the relationship between the knot / patch strength of the liquid crystal polyester multifilament and the yarn flexibility, the filament that is unraveled from the package after the completion of solid-phase polymerization is bent in a plurality of directions. It has been found that the multifilament becomes flexible by giving the knot, and the knot strength and the hook strength are greatly improved as compared with the conventional technique.

  In order to increase the flexibility of the multifilament, the direction of bending is preferably 4 directions or more, and more preferably 8 directions or more. The upper limit is not particularly limited, but is preferably 36 or less from the viewpoint of deterioration in workability at the time of yarn setting. In the present invention, from the viewpoint of threading workability and facility simplification, the 4-18 direction is a preferable range.

  The azimuth angle when bending in a plurality of directions is preferably an angle equally divided by the number of times of 360 ° bending in order to make each filament in the multifilament uniform and flexible. For example, the azimuth angle when bending in eight directions is an angle when 0 to 360 ° is divided into eight equal parts in a plane perpendicular to the longitudinal direction of the multifilament after release, and is 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, and 315 °. In addition, the azimuth angle may be bent in any order other than 0 ° (first bend).

  The distance between the guides (the distance from one bend to the next bend) is to suppress yarn blurring after the bend is applied, to prevent yarn from coming off the guide and to catch the yarn on the guide. 50 cm or more is preferable, and 100 cm or less is preferable in order to make the equipment compact.

  As a method of imparting bending, it is preferable to bend with a thread guide such as a bar guide, a loop guide, an eyelet guide, a slit guide, a hook guide, a snail guide, a roller guide, and a bearing roller guide. Therefore, it is more preferable to use a roller guide or a bearing roller guide.

  The bending angle after passing through the guide is preferably 30 ° or more, and more preferably 60 ° or more in order to effectively impart bending and increase the flexibility of the yarn. The upper limit is not particularly limited, but is preferably 90 ° or less from the viewpoint of threading workability. The bending angle here refers to an angle formed by an extension line extending in the longitudinal direction of the traveling yarn before passing through the guide and a longitudinal direction of the traveling yarn after bending through the guide.

  After bending, a liquid crystal polyester multifilament package is formed again. In the present invention, a package in the form of a pan, a drum, a cone, or the like can be used, but a drum winding package that can secure a large amount of winding is preferable from the viewpoint of productivity.

  In addition, the liquid crystalline polyester multifilament in the present invention is preferably provided with a converging property to the multifilament in order to improve process passability when it is a high-order processed product, and various finishing oils may be applied according to the purpose. Is a preferred embodiment.

  The knot strength and the hook strength of the liquid crystalline polyester multifilament of the present invention are essential to be 7.0 to 12.0 cN / dtex, preferably 7.5 to 12.0 cN / dtex, and 8.0 to 12.2. 0 cN / dtex is more preferable. By setting it as 7.0-12.0 cN / dtex, when it is set as a high-order processed product, raw yarn strength can fully be exhibited and product strength improves. On the other hand, if any one of the knot strength and the hook strength is less than 7.0 cN / dtex, sufficient strength of the product can be obtained because the yarn strength cannot be sufficiently exhibited when a high-order processed product is obtained. Absent. About the knot strength and the hook strength, the upper limit that can be reached by the manufacturing method described later is about 12.0 cN / dtex. In addition, the nodule strength and the hook strength refer to values 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 30 dtex. Moreover, it is more preferable that it is 1-20 dtex. By reducing the single fiber fineness to 1 to 30 dtex, it becomes possible to uniformly cool the inside of the single fiber after discharge, and it is easy to obtain liquid crystal polyester multifilaments with stable yarn production and good fluff quality, as well as 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 30 dtex is flexible, it is excellent in high-order process passability and has a high filling rate when used in woven fabrics. Further, the density can be increased and the storage performance can be improved. In the present invention, the quotient obtained by dividing the total fineness by the number of single fibers is defined as the single fiber fineness (dtex).

  The number of single fibers (number of filaments) of the liquid crystalline 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 T of the liquid crystal polyester multifilament of the present invention is preferably from 100 to 3,000 dtex, more preferably from 150 to 2,500 dtex, and even more preferably from 200 to 2000 dtex. By setting it as 100-3,000 dtex, it is suitable for industrial material use with high process passability 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 15.0 cN / dtex or more, and more preferably 22.5 cN / dtex or more. When the strength is 15.0 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 breaking 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 300 cN / dtex or more, more preferably 500 cN / dtex or more, and still more preferably 700 cN / dtex or more. When the elastic modulus is 300 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 1,000 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 yarn flexibility index X of the liquid crystalline polyester multifilament of the present invention is preferably 8.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less. By setting the yarn flexibility index X to 8.0 or less, the unwinding property at the time of unwinding the package is greatly improved, and the process passability at the time of high-order processing can be drastically improved. The lower limit that can be achieved in the present invention is about 0.1. The multifilament yarn softness index X is a value determined by the method described in the examples.

  The liquid crystal polyester multifilament of the present invention thus obtained has a knot strength and a hook strength of 7.0 to 12.0 cN / dtex, and the liquid crystal polyester multifilament having such characteristics is a case of a high-order processed product. In addition, the product strength is much higher than that of the conventional technology. A liquid crystal polyester multifilament having excellent knot strength and hook strength and having high strength, high elasticity, heat resistance, dimensional stability, chemical resistance, and low moisture absorption characteristics can be suitably used for general industrial material applications. it can. 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, and acoustic materials. Among these, the liquid crystal polyester multifilament excellent in knot and hook strength of the present invention can be suitably used for applications such as slings and nets where the bending of the raw yarn is high in high-order processed products.

  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)
Using a mixed solvent of pentafluorophenol / chloroform = 35/65 (weight ratio) as a solvent, the liquid crystal polyester is dissolved in the mixed solvent while stirring at 120 ° C. for 20 minutes. At this time, it prepares so that the density | concentration of liquid crystalline polyester may be 0.04 weight%, and let it be a sample for GPC measurement. This was measured using a GPC measuring apparatus manufactured by Waters, and Mw was determined 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-G (1)
Shodex K-806M (2)
Shodex K-802 (1)
Detector: differential refractive index detector RI (type 2414)
Temperature: 23 ± 2 ° C
Flow rate: 0.8 mL / min Injection rate: 0.200 mL.

(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 ultrasonically cleaned casserole is dried at 60 ° C. for 1 hour to measure the weight, and the product obtained by dividing the difference between the weight before washing and the weight after washing by the weight before washing is multiplied by 100. % By weight).

(6) Total fineness According to JIS L 1013 (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 L 1013 (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) High elongation and elastic modulus Measured under constant speed elongation conditions shown in JIS L 1013 (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 slope at the 0.5% elongation point in the stress and elongation graph in the tensile test.

(10) Nodule strength Measured under the constant speed extension condition shown in JIS L 1013 (2010) 8.6.1 standard time test. The sample was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., and the gripping interval was 250 mm and the pulling speed was 50 mm / min. The knot strength was defined as the stress at break, and the value obtained by dividing the knot strength by the total fineness of one yarn was defined as the hook strength.

(11) Hatch strength Measured under the constant speed elongation condition shown in JIS L 1013 (2010) 8.7.1 standard time test. The sample was “TENSILON” UCT-100 manufactured by Orientec Co., Ltd., and the gripping interval was 250 mm and the pulling speed was 50 mm / min. The hook strength was the stress at break, and the value obtained by dividing the hook strength by the total fineness of the two yarns was the hook strength.

(12) Bending resistance value A of multifilament
The measurement was made with reference to the constant speed deflection conditions shown in JIS K7171. That is, first, in order to unwind the filament wound and wound in the package, and cut the filament into a length of 1000 mm, one end of the filament is tied to a metal hook, and the other end is tied to a 300 g weight of breaking load, In an environment adjusted to a temperature of 25 ° C. and a relative humidity of 40%, the multifilaments were suspended vertically in the air for 24 hours to obtain measurement samples. The obtained measurement sample was further cut out with a length of 40 mm to obtain a sample piece. Using "TENSILON" UTM-4-100 manufactured by Toyo Baldwin, place the test piece obtained on the support stand installed at 5mm intervals symmetrically, and apply force with the indenter in the center between the fulcrum points of the test piece It was. With the support stand fixed, the indenter was lowered at a constant speed of 20 mm / min, and the maximum load when a force was applied to the test piece was measured to obtain a bending resistance value A (cN). The diameter of the support base and the indenter was 1.0 mm. The average value of 5 times of enforcement was used.

(13) Multifilament yarn flexibility index X
The multifilament yarn softness index X was calculated by the following equation using the bending resistance value A (cN) of the multifilament and the total fineness T (dtex) of the multifilament.
Yarn flexibility index X = (A / T) × 10 ³
(14) Process passability evaluation The package after the completion of the solid-phase polymerization is installed in the vertical direction with respect to the floor surface, and is longitudinally unraveled at 100 m / min, and multifilaments per 5,000 m are caught on the package. Evaluated the number of times stopped. ◎ (particularly good) when the number of stops is 0 to 2, ○ (good) when 3 to 5 times, △ (slightly bad) when 6 to 10 times, × (bad) when 11 times or more ).

(15) Appropriateness for high-order processed products Using a twisting machine, a single twist was added at a twist number of 100 T / m while combining five multifilaments to produce a twisted yarn. After that, according to JIS B 8811 (2015) 9.1, the twisted yarn was rotated with a measuring machine having a circumference of 1000 mm, and the four twisted yarns were bundled in a loop shape, and then both ends were fixed with tape, and round sling A core was produced. Using the obtained core, a tensile test was performed with reference to a proof load test of JIS B 8811 (2015) 10.3. That is, a metal cylinder having a diameter of 10 mm is attached to each grip of both ends of “TENSILON” RTM-1T manufactured by Orientec Co., Ltd., and both ends of the core body are hooked on the cylinder, respectively. A tensile test was performed at a speed of 50 mm / min. The stress at break was defined as sling strength (kN), and the value obtained by dividing the sling strength by the total fineness (dtex) of the core was defined as sling strength (cN / dtex). The higher the sling strength, the higher the suitability for high-order processed products, and the suitability for high-order processed products was classified according to sling strength as follows.
Suitable for high-order processed products:
5: 20 cN / dtex or more 4: 16 cN / dtex or more and less than 20 cN / dtex 3: 12 cN / dtex or more and less than 16 cN / dtex 2: 8 cN / dtex or more but less than 12 cN / dtex 1: less than 8 cN / dtex.

[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 315 ° C., and the melt viscosity measured using a Koka flow tester at a temperature of 330 ° C. and a shear rate of 1,000 / sec was 30 Pa · sec. Moreover, Mw was 145,000.

  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 a discharge amount of 100 g / min (0.33 g / single hole per single hole) from a die having 300 holes with a hole diameter of 0.13 mm and a land length of 0.26 mm. Minutes).

  Liquid crystal polyester multifilament that has been cooled and solidified at room temperature immediately after discharge is attached to an oil agent (polydimethylsiloxane ("SH200-350cSt" manufactured by Toray Dow Corning Co., Ltd., 5.0% by weight water emulsion)) using an oiling roller. The 300 filaments were taken up with a Nelson roller at 600 m / min. The spinning draft at this time is 29.3. Moreover, the oil agent adhesion amount was 1.5 weight%. The multifilament 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 in melt spinning is good, and a liquid crystal polyester multifilament having a total fineness of 1670 dtex and a single fiber fineness of 5.6 dtex can be stably spun without breaking the yarn, and a spinning yarn of 4.0 kg volume package is obtained. .

From this spinning package, the fibers are unwound in the longitudinal direction (perpendicular to the fiber circulation direction), and 400 m / min with a winder (SSP-WV8P type precision winder manufactured by Kozu Manufacturing Co., Ltd.) with a constant speed. Rewinded. 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 obtained rolled-up sample was heated from room temperature to 240 ° C. using a closed oven, held at 240 ° C. for 3 hours, then heated to 290 ° C., and further maintained at 290 ° C. for 20 hours. The solid phase polymerization was performed. The atmosphere in the solid-phase polymerization was supplied with dehumidified nitrogen at a flow rate of 100 L / min and exhausted from the exhaust port so that the interior was not pressurized.

  The solid phase polymerization package thus obtained is attached to a feeding device that can be rotated by an inverter motor, and unraveling while feeding the fibers in the transverse direction (fiber circumferential direction) at 200 m / min. A31230) was placed at a position where the yarn length was 50 cm, bent in 4 directions (4 equal divisions) at a bending angle of 60 °, and wound around a product package with a winder. The fiber properties are as shown in Table 1. The yarn softness index X of the liquid crystalline polyester multifilament of the present invention obtained in Example 1 is 6.6, the knot strength is 8.4 cN / dtex, and the hook strength is 8.3 cN / dtex. The suitability was “5”.

[Examples 2 to 4]
A method similar to that of Example 1 except that the bending applied when unpacking the solid phase polymerization package is increased in 8 directions (8 equal divisions), 18 directions (18 equal divisions), or 36 directions (36 equal divisions). A liquid crystal polyester multifilament was obtained.

[Examples 5 to 8]
A liquid crystal polyester multifilament was obtained in the same manner as in Examples 1 to 4 except that the yarn guide used was changed to a bar guide (A707096) made by Yuasa Yidomichi and the bending direction was changed as shown in Table 1. It was.

[Examples 9 to 14]
A liquid crystal polyester multifilament was obtained in the same manner as in Example 3 except that the number of holes in the die, the discharge amount and the winding speed were as shown in Table 2.

[Example 15]
A liquid crystal polyester was prepared in the same manner as in Example 3 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 physical properties of Examples 1 to 15 are shown in Tables 1 and 2.

[Comparative Examples 1-3]
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the solid phase polymerization package was not bent at the time of unwinding or bent in one direction and two directions (two equal divisions).

[Comparative Examples 4 to 5]
The liquid crystal polyester multifilament was prepared in the same manner as in Example 1 except that the bending applied when unpacking the solid-phase polymerization package was 18 directions (18 equally divided), and the bending angles when bending were 10 ° and 20 °. Obtained.

[Comparative Example 6]
The oil agent applied at the time of spinning contained 2.0% by weight of inorganic fine particles (synthetic smectite “SWN” manufactured by Coop Chemical Co., Ltd.) having an average particle size of 0.01 to 0.1 μm in an oil agent mainly composed of polyethylene glycol laurate. A liquid crystal polyester multifilament was obtained in the same manner as in Comparative Example 1 except that the oil agent was used and that the oil agent adhesion amount was changed to 0.5% by weight.
Table 3 shows the fiber physical properties of Comparative Examples 1-6.

  As is clear from Examples 1 to 15 in Tables 1 and 2, the multifilament can be softened by bending the multifilament in multiple directions when unpacking the package after the solid phase polymerization is completed. Further, a liquid crystal polyester multifilament having a knot strength and a hook strength of 7.0 to 12.0 cN / dtex can be obtained, and a high product strength was exhibited even after high-order processing. Particularly, in Examples 1 to 4 and 9 to 15, the linear strength was high, the knot strength and the hook strength were 7.5 cN / dtex or more, and higher product strength was expressed. In this way, when the knot strength and the hook strength are 7.0 to 12.0 cN / dtex, when a high-order processed product is produced, a high product strength is exhibited, which is suitable for a high-order processed product. It could be used suitably for general industrial material applications such as internet.

  On the other hand, as is clear from Comparative Examples 1 to 6 in Table 3, the multifilament yarn cannot be softened when it is not bent when bending the package after completion of solid phase polymerization or when bending is insufficient. , Became a rigid thread. Such a liquid crystal polyester multifilament has a knot strength and a hook strength of less than 7.0 cN / dtex, and when a high-order processed product is used, the strength of the raw yarn cannot be fully exhibited, so that sufficient product strength cannot be obtained. . As described above, when the knot strength and the hook strength are less than 7.0 cN / dtex, the intended effect of the present invention cannot be achieved.

  Since the liquid crystal polyester multifilament of the present invention has a knot strength and a hook strength of 7.0 to 12.0 cN / dtex, when it is made into a high-order processed product, the raw yarn strength can be sufficiently exerted and the product strength is improved. Can be made. Such a liquid crystal polyester multifilament can express a remarkably high raw yarn strength utilization rate as compared with the prior art, and therefore can be suitably used for general industrial materials such as slings and nets.

Claims (11)

  A liquid crystal polyester multifilament having a hook strength and a knot strength of 7.0 to 12.0 cN / dtex, respectively.   The liquid crystal polyester multifilament according to claim 1, wherein the strength is 15.0 cN / dtex or more.   The liquid crystal polyester multifilament according to claim 1 or 2, wherein the strength is 22.5 cN / dtex or more. The liquid crystal polyester multifilament according to any one of claims 1 to 3, 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 4, 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.   A liquid crystal polyester multifilament manufacturing method in which liquid crystalline polyester is wound around a package after melt spinning and solid-phase polymerized, and is bent in at least eight directions when the solid-phase polymerized package is unwound and then wound up again The method for producing a liquid crystal polyester multifilament according to any one of claims 1 to 5.   A high-order processed product comprising the liquid crystalline polyester multifilament according to any one of claims 1 to 5.   A rope or sling comprising the liquid crystal polyester multifilament according to any one of claims 1 to 5.   A net comprising the liquid crystal polyester multifilament according to claim 1.   A tension member comprising the liquid crystal polyester multifilament according to claim 1.   The fiber reinforced resin composition containing the liquid crystalline polyester multifilament in any one of Claims 1-5.