JP2017166110A - Liquid crystalline polyester multifilament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystalline polyester multifilament that has high strength in a direction perpendicular to the fiber axis compared to the prior arts, less likely buckles when the filament is bent, and develops high product strength after higher-order processing.SOLUTION: The liquid crystalline polyester multifilament of the present invention has a loop strength of 11 to 20 cN/dtex or more. A production method of the liquid crystalline polyester multifilament is provided, which includes melting and spinning a liquid crystalline polyester to obtain a multifilament spun fiber and subjecting the spun fiber to solid phase polymerization. Upon the solid phase polymerization, the highest temperature where the solid phase polymerization reaches is controlled to be lower by 50 to 30°C than the melting point of the spun fiber of the liquid crystalline polyester.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 suitable for industrial materials such as nets and ropes.

  Liquid crystalline polyester is a polymer composed of rigid molecular chains, and in melt spinning, the molecular chains are highly oriented in the fiber axis direction and further solid-phase polymerized at high temperatures. It is known that high strength and elastic modulus are expressed. Therefore, it is suitably used for industrial materials that require high strength and high elastic modulus.

  As such a liquid crystal polyester fiber, a fused anisotropic aromatic polyester fiber in which polysiloxane is adhered to 0.1% by weight or more of the fiber has been proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 04-024289

  However, conventional liquid crystal polyester multifilaments show high strength in the fiber axis direction, but are weak against the force in the direction perpendicular to the fiber axis and easily buckle when bent strongly. There was a problem that it was not enough.

  The fiber described in Patent Document 1 has a final ultimate temperature at the time of solid-phase polymerization that is too high, so that the stiffness of the fiber increases due to the progress of crystallization, it tends to buckle when bent, and the product strength after high-order processing is still unsatisfactory. It wasn't possible.

  The present invention has been intensively studied against the background described above, and has higher strength in the direction perpendicular to the fiber axis compared to the prior art, and is difficult to buckle even when bent, and is high after high-order processing. The object is to provide a liquid crystal polyester multifilament capable of exhibiting product strength.

  In order to achieve the above object, the present invention has the following configuration.

  (1) A liquid crystal polyester multifilament having a hook strength of 11.0 to 20.0 cN / dtex.

  (2) The liquid crystal polyester multifilament according to (1), wherein the strength is 18 cN / dtex or more.

  (3) The liquid crystal polyester multifilament according to (1) or (2), wherein the liquid crystal polyester comprises structural units (I), (II), (III), (IV) and (V) represented by the following chemical formula .

  (4) The structural unit (I) is 40 to 85 mol% based on 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 (3). Liquid crystal polyester multifilament.

  (5) The liquid crystal polyester multifilament according to any one of (1) to (4), which is used for a rope or a net.

  (6) The liquid crystal polyester multifilament according to (5) having a hook strength of 16.0 to 20.0 cN / dtex and used for a rope or a knotless net.

  (7) The liquid crystal polyester multifilament according to any one of (1) to (4), which has a hook strength of 12.5 to 15 cN / dtex and is used for a woven fabric.

  (8) The liquid crystal polyester multifilament according to any one of (1) to (4), which has a hook strength of 11.0 to 12.0 cN / dtex and is used for a knotted net.

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

  (10) When melt spinning the liquid crystalline polyester and subjecting the obtained multifilament-shaped spun fiber to solid phase polymerization, the maximum attainment temperature of the solid phase polymerization is set to the melting point of the spun fiber of the liquid crystalline polyester at −50 to −30 ° C. ( The manufacturing method of the liquid crystalline polyester multifilament in any one of 1)-(5).

  (11) When melt spinning the liquid crystalline polyester and solid-phase polymerizing the obtained multifilament-like spun fiber, the retention time at the highest temperature of solid-phase polymerization is 0 to 3 hours. Item (1) to (5), The method for producing a liquid crystal polyester multifilament according to any one of (10).

  (12) When the multifilament obtained by melt spinning the liquid crystalline polyester is subjected to solid phase polymerization, the temperature rising rate to the highest temperature of solid phase polymerization is 20 to 100 ° C./hour. (1)-(5), (10), The manufacturing method of the liquid crystal polyester multifilament in any one of (11).

  The liquid crystalline polyester multifilament of the present invention has a feature that it has high strength in the direction perpendicular to the fiber axis and is not easily buckled even if it is bent. Has strength.

  The liquid crystal polyester multifilament of the present invention is widely used in the fields of general industrial materials, civil engineering / building materials, sports applications, protective clothing, reinforcing materials, and electrical materials. Effective applications include ropes, slings, nets, fishnets, computer ribbons, printed circuit board fabrics, paper canvases, airbags, airships, dome fabrics, rider suits, fishing lines, various lines (yachts, Paragliding, balloons, kite), blind cords, support cords for screen doors, various cords in automobiles and aircraft, power transmission cords for electrical products and robots, and tension members, etc. In particular, the liquid crystalline polyester multifilament of the present invention has high durability at the intersections and bends of the fibers, and therefore is suitably used for nets and ropes.

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

  The liquid crystal polyester multifilament of the present invention is a liquid crystal polyester multifilament having a hook strength of 11 to 20 cN / dtex.

  The liquid crystal polyester used in the present invention refers to a polyester that exhibits optical anisotropy (liquid crystallinity) when heated and melted. This optical anisotropy 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 transmitted light of the sample with a polarizing microscope.

  Examples of the liquid crystalline polyester used in the present invention include (a) a polymer of aromatic oxycarboxylic acid, (b) a polymer of aromatic dicarboxylic acid and a diol selected from an aromatic diol or an aliphatic diol, and (C) The copolymer of said (a) and said (b) etc. are mentioned, Especially the polymer comprised only by the aromatic compound is used preferably. A polymer composed only of an aromatic compound exhibits excellent strength and elastic modulus when formed into a fiber. Moreover, the normal method can be used for the polymerization prescription of liquid crystal polyester.

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

  Examples of aromatic dicarboxylic acids include, for example, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, diphenylether dicarboxylic acid, diphenoxyethanedicarboxylic acid and diphenylethanedicarboxylic acid, or their alkyl, alkoxy and halogen. Substituents and the like can be mentioned.

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

  The liquid crystal polyester used in the present invention can be copolymerized with other monomers in addition to the above-mentioned monomers as long as the liquid crystallinity is not impaired. Examples of other monomers include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and dodecanedioic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, polyethers such as polyethylene glycol, poly Examples thereof include siloxane, aromatic iminocarboxylic acid, aromatic diimine, and aromatic hydroxyimine.

  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, and p-hydroxybenzoic acid. Examples thereof include liquid crystal polyester in which a component, a 4,4′-dihydroxybiphenyl component, an isophthalic acid component and / or a terephthalic acid component are copolymerized. Particularly preferred is a liquid crystal polyester in which a p-hydroxybenzoic acid component, a 4,4′-dihydroxybiphenyl component, an isophthalic acid component, a terephthalic acid component, and a hydroquinone component are copolymerized.

  In the present invention, in particular, the following chemical formula

A liquid crystalline polyester comprising the structural units (I), (II), (III), (IV) and (V) represented by In the present invention, the structural unit refers to a unit that can constitute a repeating structure in the main chain of the polymer.

  Thus, the combination of the structural units (I), (II), (III), (IV) and (V) allows the molecular chain to have appropriate crystallinity and non-linearity, that is, a melting point capable of being melt-spun. To have. 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 as in 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. This provides a relatively good wear resistance in addition to high strength and elastic modulus.

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

  Moreover, it is preferable that structural unit (II) is 60-90 mol% with respect to the sum total of structural unit (II) and (III), More preferably, it is 60-80 mol%, More preferably, it is 65-75 mol%. It is. 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.

  Furthermore, 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). It is. By setting it in such a range, the melting point of the polymer becomes an appropriate range, and it has good spinning properties at a spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, and is relatively uniform in the longitudinal direction. Fiber is obtained.

  The total amount of the structural unit (II) and the structural unit (III) and the total amount of the structural unit (IV) and the structural unit (V) are preferably substantially equimolar.

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

  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., and even more preferably 290 to 340 in terms of melt spinning and heat resistance. ° C. The melting point is an observation of an endothermic peak temperature (Tm1) observed when the temperature is measured at a temperature increase of 20 ° C./min from a temperature of 50 ° C. in a differential calorimetry performed by a differential scanning calorimeter (DSC manufactured by Perkin Elmer). Then, after holding at a temperature of Tm1 + 20 ° C. for 5 minutes, the sample is cooled to 50 ° C. at a temperature lowering rate of 20 ° C./min, and the endothermic peak temperature (Tm2) observed when measured again at a temperature rising condition of 20 ° C./min. Was the melting point.

  Further, the liquid crystal polyester used in the present invention can be used in combination with another polymer as long as the effects of the present invention are not impaired. Addition and combined use include mixing two or more polymers, using one component in a composite spinning of two or more components, or partially mixing another polymer with a plurality of components, or using the entire polymer. Say.

  Examples of other polymers used in the present invention include polyesters, vinyl polymers such as polyolefin and polystyrene, polycarbonates, polyamides, polyimides, polyphenylene sulfides, polyphenylene oxides, polysulfones, aromatic polyketones, aliphatic polyketones, and semi-aromatics. Polymers such as aromatic polyester amide, polyether ether ketone, 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, Preferred examples include polybutylene terephthalate, polyethylene naphthalate, polycyclohexanedimethanol terephthalate, and polyester 99M. And the like to.

  When these polymers are added and used in combination, the melting point of the polymer is preferably within the melting point of the liquid crystal polyester ± 30 ° C. from the viewpoint of not affecting the yarn-making property, and the strength and elastic modulus of the resulting fiber are set. In order to improve, the amount added and used in combination is preferably 50% by mass or less, more preferably 5% by mass or less.

  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. Additives such as infrared absorbers, crystal nucleating agents, fluorescent brighteners, end group capping agents, and compatibilizers can be incorporated in small amounts.

  The hook strength of the liquid crystal polyester multifilament of the present invention is essential to be 11 cN / dtex or more. By setting the hook strength to 11 cN / dtex or more, the product strength of a product having a crossed portion or a bent portion is greatly improved. When the catching strength of the fiber is less than 11 cN / dtex, it is easily broken at the bent or intersecting portion of the yarn when it is made into a product. .

  It is suitable for a rope, a knot net, etc. as it is the above-mentioned range.

  The hook strength generally correlates with the rigidity of the fiber, and the higher the hook strength, the lower the rigidity and the more the flexibility tends to increase. The higher the hook strength, the more flexible and the more difficult it is to break at the intersection / bent part, so it is particularly suitable for applications such as ropes and knotless nets. The hook strength is particularly preferably 16 to 20 cN / dtex. The bending resistance is preferably 0 to 10 mN from the viewpoint of flexibility.

  Moreover, when it exists in the range of hook strength 12.5-15cN / dtex, since it has moderate rigidity and it is excellent in form retainability, it is especially preferable for textiles use, such as a belt. The bending resistance is preferably 15 to 25 mN.

  On the other hand, if the hook strength is 11.0 to 12.0 cN / dtex, the knot is not reduced as the fiber is stiffer, and the stress is dispersed and the knot is not easily broken. It is particularly effective in applications having The bending resistance is preferably 30 to 50 mN.

  Regarding the upper limit of the catching strength, the upper limit that can be reached by the manufacturing method described later is about 20 cN / dtex. The hook strength and the bending resistance in the present invention are values obtained by the method described in the examples.

  In addition, since it becomes difficult to handle when processing as a product when rigidity is too high, the bending resistance is preferably 50 mN or less.

  The total fineness of the liquid crystal polyester multifilament of the present invention is preferably 5 to 10000 dtex for improving productivity, more preferably 10 to 10000 dtex, and further preferably 100 to 10000 dtex. Here, the total fineness is a value obtained by the method described in the examples. If the total fineness is in the above range, a yarn having no physical property difference between the inside and the outside of the yarn can be obtained during solid phase polymerization.

  The single fiber fineness of the single fiber constituting the liquid crystal polyester multifilament of the present invention is preferably 18.0 dtex or less. Here, the single fiber fineness is a value obtained by the method described in the examples. In addition to having the characteristics of improving the flexibility of the fiber and improving the processability of the fiber by reducing the fineness of the single fiber to 18 dtex or less, and improving the adhesion with the adhesive and resin because the surface area increases. In the case of weaving, there are also advantages that the thickness can be reduced, the woven density can be increased, and the opening (area of the opening) can be widened.

  The single fiber fineness is more preferably 12 dtex or less, and further preferably 7 dtex or less. About the minimum of a single fiber fineness, it is about 1 dtex as a minimum which can be reached by the above-mentioned manufacturing method.

  The number of single fibers contained in the yarn as the liquid crystal polyester multifilament of the present invention, that is, the number of filaments is preferably 10 to 1000, more preferably 50 to 500, and still more preferably 100 to 500. is there. By setting the number of filaments as described above, it is possible to obtain a thread excellent in process passability having both flexibility as a liquid crystal polyester multifilament and high tenacity (product of strength and total fineness).

  The strength of the liquid crystal polyester multifilament of the present invention is preferably 18 cN / dtex or more, more preferably 20 cN / dtex or more, and further preferably 24 cN / dtex or more. About the upper limit of intensity | strength, it is about 30 cN / dtex as an upper limit which can be reached by the manufacturing method mentioned later. The strength mentioned here is a value obtained by the method described in the examples. When the strength of the liquid crystal polyester multifilament of the present invention is 18 cN / dtex or more, it is suitably used for industrial materials that require high strength and light weight.

  The elongation of the liquid crystal polyester multifilament of the present invention is preferably 1% or more, more preferably 2% or more. By setting the elongation to 1% or more, the impact absorbability of the fibers is increased, and the process passability and handleability in the high-order processing step are improved, and the impact absorbability is increased, so that the wear resistance is also increased. About the upper limit of elongation, it is about 10% as an upper limit which can be reached by the manufacturing method mentioned later. The term “elongation” as used herein refers to a value obtained by the technique described in the examples.

  The elastic modulus of the liquid crystal polyester multifilament of the present invention is preferably 800 cN / dtex or more. The elastic modulus is more preferably 900 cN / dtex or more. Regarding the upper limit of the elastic modulus, the upper limit that can be reached by the manufacturing method described later is about the elastic modulus of 1500 cN / dtex. The elastic modulus as used in the field of this invention is a value calculated | required by the method of an Example description. By setting the elastic modulus of the liquid crystalline polyester multifilament of the present invention to 900 cN / dtex or more, the final dimensional change when a load is applied is small, and it is suitably used for industrial materials.

  Next, the manufacturing method of the liquid crystal polyester multifilament of the present invention will be described in detail.

  In melt spinning, a normal method can be used for melt extrusion of the liquid crystalline polyester, but it is preferable to use an extruder type extruder in order to eliminate the ordered structure generated during polymerization. The extruded polymer (liquid crystal polyester) is weighed by a normal metering device such as a gear pump through a pipe, and after passing through a filter for removing foreign matter, is led to a spinneret. At this time, the temperature from the polymer pipe to the spinneret (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. and not higher than 400 ° C. The melting point of the liquid crystal polyester is preferably 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 setting the temperature near the spinneret higher than the temperature on the upstream side.

  Further, in order to obtain the liquid crystal polyester multifilament of the present invention, it is preferable to improve the stability during discharge and the stability of the thinning behavior. In industrial melt spinning, in order to reduce energy costs and improve productivity, a number of base holes are perforated in one base, and it is preferable to stabilize the discharge and thinning of the base holes.

  In order to achieve these, it is preferable that the hole diameter of the base hole is made smaller and the land length (the length of the straight pipe portion the same as the diameter of the base hole) is made longer. However, since pore clogging tends to occur when the pore diameter becomes excessively small, the diameter is preferably 0.03 mm or more and 1.00 mm or less, more preferably 0.05 mm or more and 0.8 mm or less, and still more preferably. Is 0.08 mm or more and 0.60 mm or less.

  When the land length becomes excessively long, the pressure loss becomes high. Therefore, 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, more preferably It is 0.8 or more and 2.5 or less, More preferably, it is 1.0 or more and 2.0 or less.

  In order to improve the productivity of the multifilament, the number of holes in one spinneret is preferably 2 or more, and preferably 1000 or less from the viewpoint of suppressing single fiber fineness variation. The number of holes in the spinneret is more preferably 10 holes or more and 700 holes or less, and further preferably 50 holes or more and 500 holes or less.

  The introduction hole located immediately above the die hole is preferably a straight hole having a diameter of 5 times or more the diameter of the die hole from the viewpoint of not increasing pressure loss. The connecting portion between the introduction hole and the base hole is preferably tapered in order to suppress abnormal stagnation, but the length of the tapered portion should be twice or less the land length without increasing the pressure loss and streamline. This is a preferred embodiment for stabilizing the above.

  The polymer discharged from the mouthpiece hole passes through the heat retaining region and the cooling region and solidifies, and then is taken up by a roller (godet roller) that rotates at a constant speed. When the heat retention region is excessively long, the yarn-forming property is deteriorated, so that it is preferably 50 to 400 mm, more preferably 50 to 300 mm from the base surface, and the heat retention region is further preferably 50 to 200 mm. It is. In the heat retaining region, it is possible to increase the ambient temperature using a heating means.

  For the cooling, an inert gas, air, water vapor, or the like can be used. From the viewpoint of reducing the environmental load, it is preferable to use a parallel or annular air flow.

  The take-up speed is preferably 50 m / min or more for improving productivity, more preferably 300 m / min or more, and further preferably 500 m / min or more. Since the liquid crystalline polyester particularly preferably used in the present invention has a suitable spinnability at the spinning temperature, the take-up speed can be increased. The upper limit of the take-up speed is not particularly limited, but in the liquid crystal polyester particularly preferably used in the present invention, it is about 3000 m / min from the viewpoint of spinnability.

  The spinning draft defined by the quotient obtained by dividing the take-off 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. It is. Since the liquid crystalline polyester used in the present invention has a suitable spinnability, the draft can be increased, which is advantageous in improving productivity.

  In the present invention, in order to obtain the above spinning draft, it is preferable to set the polymer discharge rate to 10 to 2000 g / min, and more preferably to set to 30 to 1000 g / min, from the viewpoint of improving the spinning performance and productivity. , 50 to 500 g / min is a more preferable aspect. By setting the polymer discharge rate to 10 to 2000 g / min, a multifilament-like spun fiber of liquid crystalline polyester can be obtained with good spinning properties.

  In melt spinning, in order to improve the handleability of the fiber, it is preferable to apply an oil agent between the cooling and solidification of the polymer and the winding. As the oil agent, a general spinning oil agent can be used.

  Winding can be done in the form of parn, cheese, corn, etc. using a normal winder, but from the standpoint that the fiber is not fibrillated and does not fibrillate, a roller is applied to the package surface during winding. It is preferable to use a pan winding that does not come into contact.

  The melt-spun liquid crystal polyester spun fiber can be combined or split to adjust the number of filaments according to the purpose of use. Synthetic yarn or splitting can be performed by a known technique.

  In the present invention, when solid phase polymerization is performed in the form of a package, it is a preferred embodiment to attach an oil component to the fiber surface in order to prevent fusion of fibers. 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 adhering method may be a guide oiling method, but in order to uniformly adhere to the fibers, adhering with a kiss roll (oiling roll) made of metal or ceramic is preferable. When the fibers are in the form of a cake or tow, they can be applied by immersing them in a mixed oil. The oil adhesion rate to the fiber is preferably 0.3% by mass or more because the larger the adhesion rate, the more the fusion can be suppressed. On the other hand, if the adhesion rate is too high, sticky handling of the fibers is deteriorated, and dirt is produced in the production process and the post-processing process. Therefore, the content is preferably 30% by mass or less. The adhesion rate is more preferably 0.5% by mass or more and 20% by mass or less. The oil adhesion rate to the fiber refers to the value of the oil adhesion rate obtained by the technique described in the examples for the coated fiber.

In the present invention, solid phase polymerization is performed after applying the anti-fusing agent. By performing solid phase polymerization, the molecular weight is increased, thereby increasing the strength, elastic modulus and elongation. Solid-phase polymerization can be processed in the form of yarn, tow (for example, carried on a metal net), or continuously as a thread between rollers, but the equipment can be simplified. From the viewpoint that productivity can also be improved, it is preferable to carry out in a package form in which fibers are wound around a core material. The package winding density is preferably 0.03 g / cm ³ or more from the viewpoint of preventing the package from collapsing. On the other hand, the winding density is preferably 1.0 g / cm ² or less from the viewpoint of preventing fusion between fibers. Here, the winding density is a value calculated by Wf / Vf from the occupied volume (Vf) of the package and the mass (Wf) of the fiber obtained from the dimensions of the package and the bobbin serving as the core material.

  The bobbin used for forming the fiber package may be any cylindrical one as long as it has a cylindrical shape. When winding as a fiber package, the bobbin is attached to a winder and rotated to wind the fiber to form a package. To do. In the solid-phase polymerization, the fiber package can be processed integrally with the bobbin, but only the bobbin can be extracted from the fiber package for processing. When the treatment is performed 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 and stainless steel.

  In this case, bobbins having a large number of holes are preferable because the polymerization reaction by-products can be removed quickly and solid-phase polymerization can be performed efficiently. Moreover, when extracting and processing a bobbin from a fiber package, it is preferable to attach the outer skin to the bobbin outer layer. In any case, it is preferable to wind a cushioning material around the outer layer of the bobbin and wind up the spun fiber of the liquid crystalline polyester on the outer layer of the bobbin from the viewpoint of preventing fusion between the fiber of the innermost layer of the package and the outer layer of the bobbin. .

  In the present invention, the fiber before solid phase polymerization is referred to as a spun fiber as an intermediate product for producing the liquid crystalline polyester multifilament of the present invention.

  The cushion material is preferably felt made of organic fiber or metal fiber, and the thickness is preferably 0.1 mm or more and 20 mm or less. The above-mentioned outer skin can be substituted with this cushion material.

  The fiber mass of the fiber package is preferably in the range of 0.1 kg to 20 kg in consideration of productivity. Further, the yarn length is preferably in a range of from 10000 m to 2 million m.

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

  In the present invention, the method for obtaining the liquid crystal polyester multifilament having the hook strength defined in the present invention is not particularly limited, but an industrially practical method is to optimize the temperature conditions in the solid phase polymerization. . Specifically, it was found that a liquid crystal polyester multifilament having high catching strength can be obtained by lowering the maximum temperature and lowering the solid-phase polymerization time to a short time as compared with the prior art. . The reason is not clear, but the following mechanisms are possible. In other words, liquid crystal polyester multifilaments are increased in molecular weight and crystallized by solid-state polymerization, and the crystallization exhibits fiber rigidity. However, if the rigidity is too high, the fibers tend to buckle due to bending. It is thought that. In other words, it is considered that by performing solid-phase polymerization at a low temperature and in a short time so that crystallization does not proceed as much as possible, it becomes a flexible fiber that is resistant to bending and the hook strength is improved.

  Next, the solid phase polymerization conditions in the present invention will be described in detail.

  The maximum attainable temperature at the solid phase polymerization temperature is preferably −50 to −30 ° C., more preferably −45 to −35 ° C., of the spun fiber of the liquid crystalline polyester subjected to solid phase polymerization. By setting such a temperature, it is possible to suppress crystallization while increasing the molecular weight, achieve a high catching strength, and in a more preferred embodiment, a high strength (linear strength) can be obtained. The melting point here refers to the value obtained by the measuring method described in the examples.

  Further, in the stage before reaching the maximum temperature, it is preferable to continuously increase the solid-phase polymerization temperature with respect to time, and the rate of temperature rise is preferably 20 to 100 ° C./hour, preferably 35 to 65 ° C./hour. More preferably. By setting it as this range, while preventing fusion, crystallization is suppressed and hook strength can be improved.

  The holding time at the highest temperature is preferably 0 to 3 hours, and more preferably 1 to 2 hours, in order to suppress fiber crystallization and obtain a high catching strength.

  The temperature lowering condition from the highest temperature to the normal temperature is not particularly limited, and may be forced rapid cooling or natural cooling.

  Since the liquid crystalline polyester multifilament of the present invention has a high catching strength, it has high durability at the intersections and bends of the fibers and high strength in the product form. For this reason, the liquid crystal polyester multifilament of the present invention is widely used in fields such as general industrial materials, civil engineering and building materials, sports applications, protective clothing, reinforcing materials, and electrical materials. Effective applications include screen kites, filters, ropes, nets, fishnets, computer ribbons, printed circuit board base fabrics, paper canvases, air bags, airships, dome base fabrics, rider suits, fishing lines, various lines (Yachts, paragliders, balloons, kites), blind cords, support cords for screen doors, various cords in automobiles and airplanes, and power transmission cords for electrical products and robots, can be suitably used.

  In particular, since it is difficult to break with respect to the stress at the intersection or bend of the fiber, it is suitably used for nets and ropes.

  Next, although the liquid crystal polyester multifilament of the present invention and the method for producing the same will be described in more detail with reference to examples, the present invention is not limited to these in any way. The definition of the characteristics used in the specification text and examples, and the measuring method and calculating method of each physical property are shown below.

(1) Melting | fusing point of liquid crystalline polyester In the differential calorimetry performed with a differential scanning calorimeter (DSC2920 manufactured by TA 1n instruments), when a temperature rising condition was measured from a temperature of 50 ° C. to 20 ° C./minute using 5 mg of liquid crystalline polyester as a sample. After observing the endothermic peak temperature (Tm1) observed at 5 ° C., hold it at a temperature of Tm1 + 20 ° C. for 5 minutes, then cool it down to a temperature of 50 ° C. at a rate of temperature decrease of 20 ° C./min, and again raise the temperature at 20 ° C./min. The endothermic peak temperature (Tm2) observed at the time of measurement was taken as the melting point. The same operation was performed twice in total, and the average of the two times was defined as the melting point Tm2 (° C.) of the liquid crystal polyester.

(2) Melting | fusing point of the spinning fiber of liquid crystalline polyester In the differential calorimetry performed with a differential scanning calorimeter (TAC 1920 DSC2920), 5 mg of liquid crystalline polyester spinning fiber was used as a sample from a temperature of 50 ° C. to 20 ° C./min. The endothermic peak temperature (Tm1) observed when measuring the temperature rise condition was taken as the melting point. The same operation was performed twice in total, and the average value of the two times was defined as the melting point Tm1 (° C.) of the spun fiber of the liquid crystal polyester.

(3) Weight average molecular weight in terms of polystyrene (molecular weight)
Using a mixed solvent of pentafluorophenol / chloroform = 35/65 (mass ratio) as a solvent, the liquid crystal polyester was dissolved so that the concentration would be 0.04 to 0.08 mass / volume% to obtain a sample for GPC measurement. Was measured using a GPC measuring apparatus manufactured by Waters, and the mass average molecular weight (Mw) was determined by polystyrene conversion. The same operation was performed twice, and the average value of the two times was defined as the mass average molecular weight (Mw).
-Column: Shodex K-806M 2 pieces, K-802 1 piece-Detector: Differential refractive index detector RI (2414 type)
・ Temperature: 23 ± 2 ℃
Flow rate: 0.8 mL / min Injection volume: 200 μL.

(4) Oil content rate 100 ± 10 mg multifilament was sampled and measured for mass after drying for 10 minutes at a temperature of 60 ° C. (W 0). Dodecylbenzenesulfonic acid in 100 times more water than fiber mass The fiber is immersed in a solution containing 2.0% by mass of sodium based on the fiber mass, ultrasonically washed at 25 ° C. for 20 minutes, the washed fiber is washed with water, and dried at a temperature of 60 ° C. for 10 minutes. Mass (W1) was measured and the oil adhesion rate was calculated by the following formula.
-Oil content rate (mass%) = (W0-W1) x 100 / W1.

(5) Total fineness The total fineness was determined as the total fineness (dtex) by measuring the positive fineness at a predetermined load of 0.045 cN / dtex according to JIS L 1013 (2010) 8.3.1A method.

(6) Number of single fibers The number of single fibers was calculated by the method of JIS L 1013 (2010) 8.4.

(7) Single fiber fineness The single fiber fineness was obtained by dividing the total fineness by the number of filaments to obtain the single fiber fineness (dtex).

(8) Strength (Linear Strength), Elongation, Elastic Modulus Measured under constant speed elongation conditions shown in JIS L 1013 (2010) 8.5.1 standard time test. The sample was “TENSILON” RTM-100 manufactured by Orientec Co., Ltd., with a grip interval of 25 cm and a pulling speed of 30 cm / min. The strength and elongation were the stress and elongation at break. The elastic modulus was defined as the point at which the load change with respect to the extension change becomes maximum in the load-elongation curve.

(9) Hatch strength The tensile strength was measured under the constant speed elongation condition shown in JIS L 1013 (2010) 8.7.1 standard time test. The sample was “TENSILON” RTM-100 manufactured by Orientec Co., Ltd., with a grip interval of 25 cm and a pulling speed of 30 cm / min. The hook strength was the stress at break, and the value obtained by dividing the hook strength by the total fineness of one yarn was the hook strength.

(10) Net strength After using a cylinder knitting machine with a cylinder diameter of 4 inches (10.16 cm) and a needle number of 44 to produce a knitted liquid crystal polyester multifilament so that the basis weight is 540 g / m ² , A simple net having a length of 14 cm and a width of 10 cm was collected by cutting. The sample was made using Orientec's “TENSILON” RTM-1T, and the width direction of the knitted fabric (the direction of the wales) was fixed at a constant interval of 2 cm, a grip size of 6 cm × 6 cm, and a tensile speed of 10 cm / min. ) And the point where the stress becomes maximum between the start of elongation and the break was regarded as the net strength.

(11) Rope strength A simple rope was prepared by aligning 10 filaments of multifilament and applying S twist of 30 T / 10 cm. The sample was measured using a “TENSILON” RTM-1T manufactured by Orientec Co., Ltd. under the constant speed extension conditions shown in the JIS L 1013 (2010) 8.5.1 standard time test. The gripping interval was 25 cm, the pulling speed was 30 cm / min, and the stress at the time of breaking was the rope strength.

(12) Rigidity Based on JIS L 1096 (2010), using a “Gurley's stiffness tester” manufactured by Yasuda Seiki Co., Ltd., a 38.1 mm (1.5 inch) multifilament was used as a test piece. The softness was measured.

A, b, and c in JIS are set to 25.4 mm (1 inch), 50.8 mm (2 inches), and 101.6 mm (4 inches), and W _a , W _b, and W _c depend on the flexibility of the specimen. Depending on the case, 0 g or 5 g was appropriately changed. For each test piece, the right and left times, 10 test pieces, a total of 20 times are obtained, and the average value of one sample is obtained. The calculation method is as follows. The average value of each measured value is calculated by the following formula. The higher the value of the bending resistance, the higher the rigidity, and the bending resistance was classified as follows.
Flexibility: A: 0 to 10 mN
B: Over 10 mN and less than 15 mN C: 15 mN to 25 mN
D: More than 25 mN and less than 30 mN E: 30 to 50 mN
F: More than 50 mN / flexibility (mN) = R × {(W _a × 25.4) + (W _b × 50.8) + (W _c × 101.6)} × (L−12.7) ^{2 /} d × 3.375 × 10 ⁻⁵
However,
R: Average value of measured values W _a , W _b , W _c : Attached load (g)
L: Sample length (mm)
d: Width of multifilament yarn (mm)

<Reference Example 1>
In a 5 L reaction vessel equipped with a stirring blade and a distillation pipe, 870 g (6.30 mol) of p-hydroxybenzoic acid, 327 g (4,890 mol) of 4,4′-dihydroxybiphenyl, 89 g of hydroquinone (0.810 mol) ), 292 g (1.755 mol) of terephthalic acid, 157 g (0.945 mol) of isophthalic acid and 1460 g of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups), and from 25 ° C. with stirring in a nitrogen gas atmosphere After raising the temperature to 145 ° C. in 30 minutes, the reaction was carried out at 145 ° C. for 2 hours. Then, it heated up in 4 hours to the temperature of 335 degreeC.

  The polymerization temperature was maintained at 335 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 40 minutes. When the torque reached 28 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having a circular discharge port having a diameter of 10 mm, and pelletized by a cutter. The obtained liquid crystal polyester had a melting point (Tm2) of 313 ° C.

<Reference Example 2>
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 907 g (6.57 mol) of p-hydroxybenzoic acid, 530 g (2.81 mol) of 6-hydroxy-2-naphthoic acid and 1053 g of acetic anhydride (phenolic) The total number of hydroxyl groups was 1.10 equivalents), and the temperature was raised from 25 ° C. to 145 ° C. in 30 minutes with stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to the temperature of 325 degreeC in 4 hours.

  The polymerization temperature was kept at 325 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 40 minutes. When the torque reached 28 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having a circular discharge port having a diameter of 10 mm, and pelletized by a cutter. The obtained liquid crystal polyester had a melting point (Tm2) of 281 ° C.

Example 1
Using the liquid crystalline polyester of Reference Example 1, after vacuum drying at a temperature of 160 ° C. for 12 hours, it was melt extruded using a φ15 mm single screw extruder manufactured by Osaka Seiki Machine Co., Ltd., and spin pack while measuring with a gear pump. Was supplied with a polymer (liquid crystal polyester). The spinning temperature from the extruder to the spinning pack at this time was 345 ° C. In the spinning pack, the polymer is filtered using a metal nonwoven fabric filter, and the discharge rate is 100 g / min from a die having 300 holes with an introduction hole diameter of 2.0 mm, a hole diameter of 0.13 mm, and a land length of 0.26 mm. The polymer was discharged. The discharged polymer is passed through a 40 mm non-heated heat insulating tube (heat-retaining region), then cooled and solidified from the outside of the yarn with an annular cooling air, and then oil (polydimethylsiloxane (Toray Dow Corning) “SH200-350 cSt”) was applied to a 5.0 wt% water emulsion) and all filaments were taken up on a first godet roll of 600 m / min. After this is passed through the second godet roll at the same speed, it is wound into the shape of a PAN using a PAN winder (EFT type take-up winder manufactured by Kozu Seisakusho, no contact roll in contact with the winding package) via a dancer arm. I took it. The melting point (Tm1) of the spun fiber of the obtained liquid crystal polyester was 315 ° C. Further, the total fineness of the fiber is 1670 dtex, the single fiber fineness is 5.6 dtex, the strength is 6.4 cN / dtex, the elongation is 1.5%, the elastic modulus is 540 cN / dtex, and the oil adhesion rate is 0.5% by mass. there were.

  From this spun fiber package, winding was performed using an SSP-MV type rewinder (contact length (winding stroke of the innermost layer) 200 mm, wind number 8.7, taper angle 45 °) manufactured by Kozu Seisakusho. The spinning fiber is unwound in the longitudinal direction (perpendicular to the fiber circulation direction), and without using a speed control roller, an oiling agent (polydimethylsiloxane (Toray "SH200-350cSt" manufactured by Dow Corning Co., Ltd. was applied in an amount of 10.0% by weight of water emulsion).

A core material obtained by winding a Kevlar felt (weight per unit area: 280 g / m ² , thickness: 1.5 mm) around a stainless boring bobbin was used as the wound core material, and the surface pressure was 100 gf. The fiber mass of the package after rewinding was 1.0 kg, the package winding density was 0.6 g / cm ³ , and the oil adhesion rate to the fiber was 3.0% by mass.

  Next, the stainless steel boring bobbin was removed from the wound package, and solid phase polymerization was performed in a package state in which the fiber was wound around Kevlar felt. The solid phase polymerization was performed using a closed oven under the condition that the temperature was raised from 25 ° C. to 275 ° C. at a rate of 80 ° C./hour and held at a temperature of 275 ° C. for 1 hour. The atmosphere was supplied with dehumidified nitrogen at a flow rate of 20 NL / min, and was exhausted from the exhaust port so that the interior was not pressurized. After holding at the highest temperature, heating was stopped and the product was naturally cooled to room temperature (25 ° C.).

The total fineness of the obtained fiber after solid phase polymerization is 1670 dtex, the single fiber fineness is 5.6 dtex, the strength is 24.0 cN / dtex, and the elongation is 2.5%. Compared with the fiber before solid phase polymerization It was confirmed that the strength and elongation were improved and solid phase polymerization was progressing.
Table 1 shows the hook strength, net strength, rope strength and flexibility of the fiber after the solid phase polymerization.

(Examples 2 and 3)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the maximum temperature holding time of solid phase polymerization was changed to 3 hours (h) and 0 h, respectively. The results are shown in Table 1.

(Examples 4 and 5)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the maximum temperature of solid phase polymerization was changed to 265 ° C. and 285 ° C., respectively. The results are shown in Table 1.

(Examples 6 and 7)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the temperature rising rate of solid phase polymerization was changed to 20 ° C. and 80 ° C./hour, respectively. The results are shown in Table 1.

(Examples 8 to 10)
Same as Example 1 except that the liquid crystalline polyester of Reference Example 2 was used, the spinning temperature was changed to 320 ° C., and the maximum reached temperatures of solid phase polymerization were changed to 241 ° C., 251 ° C., and 231 ° C., respectively. Thus, a liquid crystal polyester multifilament was obtained. The melting point of the spun fiber of the obtained liquid crystal polyester was 281 ° C. The results are shown in Table 1.

(Comparative Examples 1-3)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the maximum temperature of solid phase polymerization was changed to 310 ° C, 290 ° C, and 255 ° C. The results are shown in Table 2.

(Comparative Example 4)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the maximum temperature retention time for solid phase polymerization was changed to 8 h. The results are shown in Table 2.

(Comparative Examples 5 and 6)
A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the temperature increase rate of the solid phase polymerization was changed to 120 ° C./hour and 10 ° C./hour. The results are shown in Table 2.

(Comparative Example 7)
A liquid crystal polyester multifilament was prepared in the same manner as in Example 1 except that the liquid crystal polyester of Reference Example 2 was used, the spinning temperature was changed to 320 ° C., and the maximum temperature reached in solid phase polymerization was changed to 276 ° C. Obtained. The melting point of the obtained spun fiber was 281 ° C. The results are shown in Table 2.

(Comparative Example 8)
Using the liquid crystalline polyester of Reference Example 2, changing the spinning temperature to 320 ° C., in the solid phase polymerization process at 260 ° C. for 1 hour, from 270 ° C. to 280 ° C. for 3 hours, from 280 ° C. to 285 ° C. for 5 hours. A liquid crystal polyester multifilament was obtained in the same manner as in Example 1 except that the heat treatment was performed. The melting point of the obtained spun fiber was 281 ° C. The results are shown in Table 2.

  As is clear from Examples 1 to 10 in Table 1, the liquid crystal polyester multifilament having a catching strength of 11 cN / dtex or more can be obtained by appropriately setting the maximum reached temperature, the holding time, and the heating rate of the solid phase polymerization. It can be obtained stably and can exhibit high net strength and rope strength. Among them, the fibers obtained in Examples 4 and 9 are used for knots such as knotted nets (especially because the fibers have good catching strength and excellent rigidity, so that stress at knots is easily dispersed (particularly It is suitable for a net having a knot, a rope used by forming a knot, and the like, and the fibers obtained in Examples 5, 6, and 10 have an appropriate hook strength and an appropriate rigidity. It is suitable for textile applications such as belts, and the fibers obtained in Examples 1-3, 7, and 8 have high hook strength, are flexible, and are difficult to break at intersections and bends. It is suitable for such applications.

  On the other hand, as apparent from Comparative Examples 1 to 8 in Table 2, when the solid phase polymerization conditions were not appropriate, high hook strength, net strength, and rope strength were not obtained.

Claims (12)

  A liquid crystal polyester multifilament having a hook strength of 11 to 20 cN / dtex.   The liquid crystal polyester multifilament according to claim 1, wherein the strength is 18 cN / dtex or more. The liquid crystalline polyester multifilament according to claim 1 or 2, wherein the liquid crystalline polyester comprises structural units (I), (II), (III), (IV) and (V) represented by the following chemical formula.

  The structural unit (I) is 40 to 85 mol% based on the total of the structural units (I), (II) and (III), and the structural unit (II) is added to the total of the structural units (II) and (III). The liquid crystalline polyester multifilament according to any one of claims 1 to 3, wherein the proportion is 60 to 90 mol%, and the structural unit (IV) is 40 to 95 mol% based on the total of the structural units (IV) and (V). .   The liquid crystal polyester multifilament according to any one of claims 1 to 4, which is used for a rope or a net. The liquid crystal polyester multifilament according to claim 5, which has a catching strength of 16.0 to 20.0 cN / dtex and is used for a rope or a knotless net. The liquid crystal polyester multifilament according to any one of claims 1 to 4, which has a catching strength of 12.5 to 15 cN / dtex and is used for a woven fabric. The liquid crystal polyester multifilament according to any one of claims 1 to 4, which has a hook strength of 11.0 to 12.0 cN / dtex and is used for a knotted net.   A rope comprising the liquid crystal polyester multifilament according to any one of claims 1 to 5.   The liquid crystal polyester is melt-spun, and when the obtained multifilament-like spun fiber is solid-phase polymerized, the maximum attainment temperature of the solid-phase polymerization is a melting point of the liquid crystal polyester spun fiber of -50 to -30 ° C. 6. A process for producing a liquid crystal polyester multifilament according to any one of 5 above.   When the liquid crystalline polyester is melt-spun and the obtained multifilament-like spun fiber is solid-phase polymerized, the retention time at the highest temperature of solid-phase polymerization is 0 to 3 hours. The method for producing a liquid crystal polyester multifilament according to any one of 8 and 10.   9. A solid-state polymerization of a multifilament obtained by melt spinning a liquid crystalline polyester, wherein the rate of temperature rise to the maximum temperature of solid-phase polymerization is 20 to 100 ° C./hour. The manufacturing method of the liquid-crystal polyester multifilament in any one of 10,11.