JP5915227B2 - Liquid crystal polyester fiber and method for producing the same - Google Patents

Description

  The present invention relates to a liquid crystal polyester fiber having high strength and high elastic modulus, and excellent process passability and post-processability, and a method for producing the same.

  Liquid crystalline polyester is a polymer composed of rigid molecular chains. In melt spinning, the molecular chains are highly oriented in the fiber axis direction, and further subjected to heat treatment (solid phase polymerization). It is known that the highest strength and elastic modulus can be obtained. It is also known that liquid crystalline polyesters have increased molecular weight due to solid phase polymerization and increased melting point, so that heat resistance and dimensional stability are improved (for example, see Non-Patent Document 1). Thus, liquid crystal polyester fibers exhibit high strength, high elastic modulus, excellent heat resistance, and thermal dimensional stability by solid phase polymerization.

Solid-phase polymerization of liquid crystal polyester is generally performed at a high temperature that does not exceed the melting point, and therefore it is important to provide a solid-phase polymerization oil for the purpose of preventing fusion between yarns.
On the other hand, solid-phase polymerization oils accumulate on guides and rollers in the process after the solid-phase polymerization process and become scraps called scum, causing tension fluctuations and causing problems such as deterioration of process passability. , The solid-phase polymerized oil remains in the fiber, which deteriorates the post-processability, for example, when applying resin (coating) as a tension member, or when applying chemicals or resin impregnation as a resin or rubber reinforcement. There was a problem to make.

For example, Patent Documents 1 and 2 disclose a technique for suppressing sticking between fibers by applying inorganic particles having high heat resistance to the fiber surface. Although this technique is certainly effective in suppressing sticking, the inorganic particles adhere firmly to the fiber surface or between the fibers, and the excessively adhered inorganic particles easily fall off from the fiber surface, resulting in poor post-processability. There was a problem.
Patent Documents 3 and 4 disclose techniques for suppressing fusion between fibers by using inorganic particles and polysiloxane for the fibers after melt spinning. Although it has been shown in this technique that a combination of inorganic particles and polysiloxane exhibits a high effect in suppressing fusion (Patent Document 3), it has been found that the polysiloxane used in combination has a problem.

  That is, polysiloxane undergoes gelation due to cross-linking reaction between polysiloxanes under solid-state polymerization conditions, and this gelled product adheres firmly to the fiber surface. During processing, it was found that scum accumulates on the guide and the roller and deteriorates the process passability. In addition, the polysiloxane gelled product has high tackiness, and when it is deposited as scum, it causes a large fluctuation in tension due to the adhesive force with the fiber.

Furthermore, since the gelated product of polysiloxane adheres firmly to the fiber surface, it has also been found that it remains on the fiber even when mechanical cleaning such as ultrasonic cleaning is performed in addition to cleaning with a surfactant. From this, the problem of deteriorating the post-processability of the fiber, particularly the adhesiveness, has been clarified.
Thus, although the solid-phase polymerization oil agent of the liquid crystalline polyester fiber is indispensable to suppress the fusion, on the other hand, due to the presence of the solid-phase polymerization oil agent, deterioration of process passability in the subsequent process, Post-workability may be deteriorated.

JP 2004-107826 A (page 2) JP 2006-336147 A (page 6) JP 2009-228177 A (second page) JP 2008-240229 A (15th and 16th pages)

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

  The object of the present invention is high-strength, high elastic modulus, less fusion between fibers, excellent process passability in the subsequent process, and solid-phase polymerization excellent in post-processability when making into a product It is in providing a liquid crystal polyester fiber and its manufacturing method.

The above-described object of the present invention is achieved by the following means.
(1) A method for producing a liquid crystal polyester fiber (2), wherein the inorganic particles (A) and the phosphoric acid compound (B) are applied to the yarn obtained by melt spinning the liquid crystal polyester, followed by solid phase polymerization. ) Liquid crystal polyester fiber obtained by the production method described in (1) above.

  Since the liquid crystalline polyester fiber of the present invention has high strength and high elastic modulus, there is little fusion between the fibers, and it is excellent in process passability in the subsequent process, and further excellent in post-processability when making the product, The productivity of textile products can be increased. In particular, it is excellent in adhesiveness with a chemical solution or resin when used as a tension member, resin or rubber reinforcement. Moreover, the liquid crystalline polyester fiber of the present invention can be efficiently produced by the production method of the present invention.

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

Examples of the liquid crystal polyester used in the present invention include (i) a polymer of aromatic oxycarboxylic acid, (ii) a polymer of aromatic dicarboxylic acid and aromatic diol, and aliphatic diol, (iii) (i) and ( Examples include ii) copolymers and the like. Among these, polymers composed only of aromatic dicarboxylic acids and aromatic diols are preferred. Polymers composed only of aromatics exhibit excellent strength and elastic modulus when made into fibers. Moreover, conventionally well-known method can be used for the polymerization prescription of liquid crystalline polyester.
Here, examples of the aromatic oxycarboxylic acid include hydroxybenzoic acid, hydroxynaphthoic acid and the like, or alkyl, alkoxy and halogen substituted products thereof.

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

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

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

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

  A combination such as the above (I), (II) and (III) causes the molecular chain to have appropriate crystallinity and non-linearity, that is, a melting point capable of being melt-spun. Therefore, the fiber has a good spinning property at the spinning temperature set between the melting point of the polymer and the thermal decomposition temperature, and a uniform fiber is obtained in the longitudinal direction. The rate can be increased. In particular, the combination of (III) is most preferable because it has high linearity and can increase the elastic modulus.

  In addition, other polymers can be added to or 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. Polyphenylene sulfide, polyether ether ketone, nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate Preferred examples include phthalate, polycyclohexanedimethanol terephthalate, and polyester 99M. In addition, when these polymers are added and used in combination, it is preferable that the melting point is within the melting point of the liquid crystal polyester ± 30 ° C. so as not to impair the spinning property, and to improve the strength and elastic modulus of the obtained fiber. The amount to be added and used in combination is preferably 50% by weight or less, more preferably 5% by weight or less, and most preferably no other polymer is added or used in combination.

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

  The melting point of the liquid crystalline polyester used in the present invention is preferably 200 to 380 ° C. in order to widen the temperature range in which melt spinning is possible, and more preferably 250 to 360 ° C. in order to improve the spinnability. In addition, melting | fusing point of liquid crystal polyester polymer points out the value (Tm2) measured by the method of an Example description.

  The polystyrene equivalent weight average molecular weight (hereinafter referred to as molecular weight) of the liquid crystalline polyester used in the present invention is preferably 30,000 or more. By setting the molecular weight to 30,000 or more, it has an appropriate viscosity at the spinning temperature and can improve the spinning property. The higher the molecular weight, the higher the strength, elongation, and elastic modulus of the resulting fiber. However, if the molecular weight is too high, the viscosity becomes high and the fluidity deteriorates. The following is more preferable. Here, the weight average molecular weight in terms of polystyrene refers to a value measured by the method described in the examples.

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

  In melt spinning, a known method can be used for melt extrusion of liquid crystal polyester, but an extruder type extruder is preferably used in order to eliminate the ordered structure generated during polymerization. The extruded polymer is measured by a known measuring device such as a gear pump through a pipe, and after passing through a filter for removing foreign matter, is guided to a base. At this time, the temperature from the polymer pipe to the die (spinning temperature) is preferably not less than the melting point of the liquid crystal polyester, and more preferably not less than the melting point of the liquid crystal polyester + 10 ° C. in order to improve fluidity. However, if the spinning temperature is excessively high, the viscosity of the liquid crystal polyester increases, leading to deterioration of fluidity and yarn-making property. Therefore, the temperature is preferably 500 ° C. or less, and more preferably 400 ° C. or less. It is also possible to independently adjust the temperature from the polymer pipe to the base. In this case, the discharge is stabilized by making the temperature of the part close to the base higher than the temperature on the upstream side.

  In discharging, it is preferable to reduce the diameter of the mouthpiece hole and to increase the land length (the length of the straight pipe portion that is the same as the diameter of the mouthpiece hole) from the viewpoint of improving the yarn-making property and improving the uniformity of the fineness. However, when the hole diameter is excessively small, clogging of the hole is likely to occur, and the diameter is preferably 0.05 mm or more and 0.50 mm or less, and more preferably 0.10 mm or more and 0.30 mm or less. If the land length is 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 1.0 or more and 3.0 or less, and preferably 2.0 or more and 2.5 or less. Is more preferable.

  In order to maintain uniformity, the number of holes in one die is preferably 1000 holes or less, and more preferably 500 holes or less. In addition, it is preferable that the introduction hole located immediately above the die hole is a straight hole in terms of not increasing pressure loss. In order to suppress abnormal stagnation, it is preferable that the connecting portion between the introduction hole and the die hole is tapered.

  The polymer discharged from the base hole passes through a heat retaining and cooling region and solidifies, and is then taken up by a roller (godet roller) that rotates at a constant speed. If the heat-retaining region is excessively long, the yarn forming property is deteriorated, so that it is preferably up to 200 mm from the base surface, and more preferably up to 100 mm. In the heat retaining region, the atmospheric temperature can be increased by using a heating means, and the temperature range is preferably 100 ° C. or higher and 500 ° C. or lower, and more preferably 200 ° C. or higher and 400 ° C. or lower. For the cooling, an inert gas, air, water vapor or the like can be used, but it is preferable to use an air flow at room temperature (20 to 30 ° C.) which is jetted in parallel or in a ring shape from the viewpoint of lowering the environment and energy load.

  The take-up speed is preferably 50 m / min or more, more preferably 500 m / min or more for improving productivity and reducing the fineness of the single yarn. The liquid crystalline polyester mentioned as a preferred example in the present invention has a suitable spinnability at the spinning temperature, so that the take-up speed can be increased, and the upper limit is not particularly limited, but is about 2000 m / min from the viewpoint of spinnability.

  The spinning draft defined by the quotient obtained by dividing the take-up speed by the discharge linear speed is preferably 1 or more and 500 or less, and more preferably 10 or more and 100 or less from the viewpoint of improving the spinning property and improving the uniformity of the fineness.

  In melt spinning, it is preferable to add an oil agent between the cooling and solidification of the polymer and the winding to improve the handleability of the fiber. As the oil agent, a known oil agent can be used, but it is generally used in terms of improving the unwinding property when unwinding the fiber obtained by melt spinning in the rewinding before solid-phase polymerization (hereinafter referred to as a spinning yarn). It is preferable to use a spinning oil or a mixed oil of inorganic particles (A) and a phosphoric acid compound (B) described later.

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

  If the total fineness of the fiber obtained by melt spinning, that is, the fiber to be subjected to solid-phase polymerization, is too small, fusion between yarns is likely to occur during solid-phase polymerization, which becomes a defect during unwinding and processability. Is preferably 5 dtex or more, more preferably 20 dtex or more, and even more preferably 100 dtex or more. The total fineness mentioned here is a value obtained by the technique described in the examples. Further, if the total fineness is excessively large, there is a difference between the inside and the outside of the yarn at the time of solid-phase polymerization, and the single yarn is likely to be broken, and is preferably 10,000 dtex or less, more preferably 2000 dtex or less in order to deteriorate the process passability. .

  The single fiber fineness of the fiber obtained by melt spinning is preferably 18.0 dtex or less. The single fiber fineness referred to here is a value obtained by the method described in the examples. By reducing the single fiber fineness to 18.0 dtex or less, the molecular weight of the polymer constituting the fiber is likely to increase when solid-phase polymerization is performed in the fiber state, and the strength, elongation, and elastic modulus are improved. Furthermore, since the surface area is increased, the adhesion amount of the inorganic particles (A) and the phosphoric acid compound (B) can be increased. The single fiber fineness is more preferably 10.0 dtex or less, and even more preferably 7.0 dtex or less. The lower limit of the single fiber fineness is not particularly limited, but the lower limit that can be achieved by this method is about 1.0 dtex.

  The number of single yarns contained in the yarn, that is, the number of filaments, is preferably 1 or more, more preferably 5 or more, further preferably 50 or more, and most preferably 100 or more. By increasing the number of filaments, even when the single fiber fineness is small, the total fineness can be increased, and the yarn has the flexibility and high strength (product of strength and total fineness), and thus has excellent processability. If the number of filaments is excessively large, the handleability is inferior, so the upper limit is about 5000.

  The strength of the fiber obtained by melt spinning is preferably 3.0 cN / dtex or more, and is preferably 5.0 cN / dtex or more in order to prevent yarn breakage in the rewinding step before solid phase polymerization, which is the next step, and to improve process passability. Is more preferable. The upper limit of strength is about 10 cN / dtex in the present invention.

  The elongation of the fiber obtained by melt spinning is preferably 0.5% or more, and is preferably 1.0% or more in order to prevent yarn breakage in the rewinding step before solid phase polymerization, which is the next step, and to improve process passability. More preferred. The upper limit of elongation is about 5.0% in the present invention.

  The elastic modulus of the fiber obtained by melt spinning is preferably 300 cN / dtex or more, more preferably 500 cN / dtex or more in order to prevent yarn breakage in the rewinding step before solid phase polymerization, which is the next step, and to improve process passability. . The upper limit of the elastic modulus is about 800 cN / dtex in the present invention.

In the present invention, the strength, elongation, and elastic modulus are values obtained by the method described in the examples.
The molecular weight of the fiber obtained by melt spinning is preferably 30,000 or more. By setting the molecular weight to 30,000 or more, high strength, elongation, and elastic modulus can be obtained, and process passability is excellent. Further, if the molecular weight is too high, solid phase polymerization is difficult to proceed and the reachable molecular weight cannot be increased, so the molecular weight is preferably 250,000 or less, more preferably 200,000 or less. Here, the weight average molecular weight in terms of polystyrene refers to a value measured by the method described in the examples. In the present invention, the change in molecular weight is small during melt spinning.

  The present invention is characterized in that solid-phase polymerization is performed after applying inorganic particles (A) and a phosphoric acid compound (B) to liquid crystal polyester fibers. In addition to the effect of suppressing fusion occurring between fibers during solid phase polymerization by applying inorganic particles (A) and phosphoric acid compound (B), the component is thermally denatured in the solid phase polymerization step. It excels in process passability in the post-process, and is excellent in post-processability when making a product. In the present invention, since the inorganic particles (A) and the phosphoric acid compound (B) are used as the oil for solid phase polymerization, the oil component is not used, but the inorganic particles (A) and the phosphoric acid compound (B) are also used. Expressed as “oil agent for solid phase polymerization”.

  The inorganic particles (A) in the present invention are known inorganic particles, and examples include minerals, metal hydroxides such as magnesium hydroxide, metal oxides such as silica and alumina, and carbonates such as calcium carbonate and barium carbonate. In addition to compounds, sulfate compounds such as calcium sulfate and barium sulfate, carbon black and the like can be mentioned. By applying such heat-resistant inorganic particles onto the fibers, it is possible to reduce the contact area between the single yarns and avoid the fusion that occurs during solid phase polymerization.

  The inorganic particles (A) are easy to handle in consideration of the coating process, are preferably easy to disperse in water from the viewpoint of reducing the environmental load, and are preferably inert under solid-state polymerization conditions. From these viewpoints, it is preferable to use silica or a silicate mineral. In the case of a silicate mineral, a phyllosilicate having a layered structure is particularly preferable. Examples of phyllosilicates include kaolinite, hallolite, serpentine, silica nickel ore, smectite group, granite, talc, and mica. Of these, talc and mica are considered in view of availability. Most preferably, is used.

  Moreover, as a median diameter (D50) of an inorganic particle (A), 10 micrometers or less are preferable. This is because, by setting D50 to 10 μm or less, the probability that the inorganic particles (A) are held between the fibers is increased, and the fusion suppressing effect becomes remarkable. For the same reason, D50 is more preferably 5 μm or less. In addition, the lower limit of D50 is preferably 0.01 μm or more in consideration of the cost and the detergency in the washing step after solid phase polymerization. The median diameter (D50) here is a value measured by the method described in the examples.

  Moreover, as a phosphoric acid type compound (B) in this invention, the compound shown by following Chemical formula (1)-(3) can be used.

Here, R ₁ and R ₂ are hydrocarbons, M ₁ is an alkali metal, M ₂ is any one of an alkali metal, hydrogen, a hydrocarbon, and an oxygen-containing hydrocarbon. Note that n represents an integer of 1 or more.
As R ₁ , in consideration of the gas generated by thermal decomposition during solid phase polymerization, it is preferable that the structure does not contain a phenyl group, and more preferably an alkyl group, from the viewpoint of reducing the environmental load. The carbon number of R ₁ is preferably 2 or more from the viewpoint of affinity for the fiber surface, and suppresses the weight loss rate due to decomposition of the organic component accompanying solid phase polymerization, and is generated by decomposition during solid phase polymerization. Is preferably 20 or less from the viewpoint of preventing the remaining on the fiber surface. R ₂ is preferably a hydrocarbon having 5 or less carbon atoms, more preferably 2 or 3 carbon atoms from the viewpoint of solubility in water. M ₁ is preferably sodium or potassium because it is inexpensive and easily available.

  The important point in the present invention is to use the phosphoric acid compound (B) in combination with the inorganic particles (A). By using the phosphoric acid compound (B) in combination, the dispersibility of the inorganic particles (A) in a medium such as water can be increased and uniform application to the fiber can be achieved, and an excellent fusion suppressing effect can be exhibited. The phosphoric acid compound (B) is thermally denatured during solid-phase polymerization, that is, synergism due to the formation of a condensed salt of phosphate by dehydration reaction and decomposition of the organic component contained in the phosphoric acid compound (B). I found the effect.

  One of the effects is an improvement in process passability due to the fact that the inorganic particles (A) and the condensed salt of phosphate adhere uniformly to the fiber surface after solid-phase polymerization. When the salt and particles that are powders are coated on the fiber surface, the running resistance is reduced by the action of powder release, and fibrillation due to fiber abrasion can be prevented. In addition, the presence of the condensed salt of phosphate prevents the inorganic particles (A) from adhering to the fiber surface, while the inorganic particles (A) adhering excessively fall off from the fiber surface. Can be suppressed, and process passability and post-workability can be improved. On the other hand, a polysiloxane compound known as a prior art produces a polysiloxane gel, so that the surface has high adhesiveness and the running resistance is high, so the process passability cannot be stabilized.

  Another effect is that both the inorganic particles (A) and the condensed salt of phosphate can coexist and can be easily washed away with water. By this effect, by washing with water when making a product, it is possible to create a state in which there is substantially no deposit on the fiber surface, and it is possible to improve the adhesion to chemicals and resins. The mechanism for improving the cleanability is that the inorganic particles (A) are hygroscopic when used in combination with the inorganic particles (A), so that the condensed salt of the phosphoric acid compound (B) naturally absorbs and deliquesces. It is speculated that the condensed salt of the phosphoric acid compound (B) expands by absorbing water only when it comes into contact with water, and peels off in layers from the fiber surface together with the inorganic particles (A). In addition, when the phosphoric acid compound (B) is applied alone, the phosphate is absorbed and deliquescent on the fiber surface even under normal fiber storage conditions due to the deliquescence of the condensed salt. Sex is reduced. Moreover, in the polysiloxane compound known as a prior art, since the gel-like substance of polysiloxane produces | generates, a gel-like substance remains on the surface.

  In order to uniformly apply the inorganic particles (A) and the phosphoric acid compound (B) with an appropriate amount of adhesion, use a mixed oil obtained by adding the inorganic particles (A) to the diluted solution of the phosphoric acid compound (B). It is preferable to use water as the diluent from the viewpoint of safety. From the viewpoint of suppressing fusion, the concentration of the inorganic particles (A) in the diluted solution is desirably high and is preferably 0.01% by weight or more, more preferably 0.1% by weight or more. To 10% by weight or less, more preferably 5% by weight or less. Further, the concentration of the phosphoric acid compound (B) in the diluted solution is desirably high from the viewpoint of uniform dispersion of the inorganic particles (A), and is 0.1 wt% or more, more preferably 1.0 wt% or more. is there. The upper limit of the concentration of the phosphoric acid compound (B) is not particularly limited, but is preferably 50% by weight or less for the purpose of avoiding excessive adhesion due to an increase in the viscosity of the mixed oil agent and adhesion spots due to an increase in temperature dependency of the viscosity. More preferably, it is 30% by weight or less.

  In addition, as a method of applying the inorganic particles (A) and the phosphoric acid compound (B) to the fiber, it may be performed from melt spinning to winding, but in order to increase the adhesion efficiency, the spinning yarn is used. It is preferable to apply while rewinding or to apply a small amount by melt spinning and to apply additionally while rewinding. The adhering method may be a guide oiling method, but in order to uniformly adhere to fine fibers such as monofilaments, adhering with a metal or ceramic kiss roll (oiling roll) is preferable. In addition, when a fiber is a cake shape and a tow shape, it can apply | coat by immersing in a mixed oil agent.

In addition, when the adhesion rate of the inorganic particles (A) to the fiber is (a) wt% and the adhesion rate of the phosphoric acid compound (B) is (b) wt%, the following conditions are preferably satisfied.
Condition 1. 30 ≧ a + b ≧ 2.0
Condition 2. a ≧ 0.05
Condition 3. 10 ≧ b / a ≧ 1
In the above-mentioned condition 1, since the adhesion can be suppressed as the oil component adhesion rate (a + b) of the solid phase polymerization oil increases, 2.0% by weight or more is preferable. It is preferably 30% by weight or less because soiling occurs in the process and the post-processing process. More preferably, it is 4.0 weight% or more and 20 weight% or less. The oil adhesion rate (a + b) of the solid phase polymerization oil to the fiber refers to the value of the oil adhesion rate obtained by the technique described in the examples for the fiber after application of the solid phase polymerization oil.
Under condition 2, the adhesion rate (a) of the inorganic particles (A) is 0.05% by weight or more, so that the effect of suppressing fusion by the inorganic particles becomes remarkable. The upper limit of the adhesion rate (a) is 5% by weight or less from the viewpoint of uniform adhesion.
In condition 3, the ratio (b / a) of the adhesion rate (b) of the phosphoric acid compound (B) to the adhesion rate (a) of the inorganic particles (A) is set to 1 or more so that the phosphoric acid compound (B) The excellent detergency derived from the formation of the condensation salt during solid phase polymerization is more prominent, and is also preferable from the viewpoint of suppressing the sticking and dropping between the inorganic particles (A) and the fibers. In order to prevent the condensed salt of the phosphoric acid compound (B) from absorbing and deliquescent due to the hygroscopicity of the inorganic particles (A), and to obtain excellent process passability and detergency, (b / a) is used. 10 or less is preferable.
Here, the adhesion rate (a) of the inorganic particles (A) and the adhesion rate (b) of the phosphoric acid compound (B) refer to values calculated by the following equations.
(Adhesion rate of inorganic particles (A) (a)) = (a + b) × Ca ÷ (Ca + Cb)
(Adhesion rate of phosphoric acid compound (B) (b)) = (a + b) × Cb ÷ (Ca + Cb)
Here, Ca indicates the concentration of the inorganic particles (A) in the solid phase polymerization oil, and Cb indicates the concentration of the phosphoric acid compound (B) in the solid phase polymerization oil.

  In the present invention, solid phase polymerization is performed after applying the inorganic particles (A) and the phosphoric acid compound (B). By performing solid phase polymerization, the molecular weight is increased, thereby increasing strength, elastic modulus, and elongation. Solid-phase polymerization can be processed in the form of a cake, tow (for example, on a metal net), or continuously as a thread between rollers, but the equipment can be simplified and productivity can be improved. It is preferable to carry out in the form of a package in which fibers are wound around a core from the point.

  When performing solid phase polymerization in the form of a package, the winding density of the fiber package at the time of performing solid phase polymerization is important for preventing fusion, and the winding density is 0.01 g / cc or more in order to prevent collapse. In order to avoid fusion, the winding density is preferably 1.00 g / cc or less, and more preferably 0.80 g / cc or less. Here, the winding density is a value calculated by Wf / Vf from the occupied volume Vf (cc) of the package and the weight Wf (g) of the fiber obtained from the outside dimensions of the package and the dimensions of the bobbin that is the core material. In addition, if the winding density is excessively small, the package collapses, so that 0.03 g / cc or more is preferable. The occupied volume Vf is a value obtained by actually measuring the outer dimension of the package or by taking a photograph and measuring the outer dimension on the photograph and assuming that the package is rotationally symmetric. Wf is the fineness And a value calculated from the winding length, or a value measured by a weight difference before and after winding.

  Such a package having a low winding density is desirable for improving facility productivity and production efficiency when formed by winding in melt spinning. On the other hand, a package wound by melt spinning is formed by rewinding. In this case, it is preferable because the winding tension can be reduced and the winding density can be further reduced. In the rewinding, the winding density can be reduced as the winding tension is reduced. Therefore, the winding tension is preferably 0.30 cN / dtex or less, and more preferably 0.20 cN / dtex or less. The lower limit is not particularly defined, but the lower limit that can be reached in the present invention is about 0.01 cN / dtex.

  In order to reduce the winding density, the rewinding speed is preferably 500 m / min or less, and more preferably 400 m / min or less. On the other hand, a higher rewinding speed is advantageous for productivity, and it is preferably 50 m / min or more, particularly preferably 100 m / min or more.

  In order to form a stable package even at low tension, the winding form is preferably a taper end winding with both ends tapered. At this time, the taper angle is preferably 60 ° or less, and more preferably 45 ° or less. When the taper angle is small, the fiber package cannot be enlarged, and when long fibers are required, it is preferably 1 ° or more, and more preferably 5 ° or more. The taper angle referred to in the present invention is defined by the following equation.

  Furthermore, the number of winds is also important for package formation. The number of winds is the number of times the spindle rotates during a half-reciprocation of the traverse, and is defined as the product of the time (minutes) of the traverse half-reciprocation and the number of spindle rotations (rpm). It shows that. The smaller the number of winds, the smaller the contact area between the fibers, which is advantageous for avoiding fusion. However, the higher the number of winds, the lower the end face and the swelling of the package, and the better the package shape. From these points, the wind number is preferably 2 or more and 20 or less, more preferably 5 or more and 15 or less.

  The bobbin used to form the fiber package may be of any cylindrical shape, and when wound as a fiber package, it is attached to a winder and rotated to wind the fiber and form a package. . In the solid-phase polymerization, the fiber package can be processed integrally with the bobbin, but the bobbin alone can be extracted from the fiber package for processing. When the treatment is carried out while being wound around the bobbin, the bobbin needs to withstand the solid phase polymerization temperature, and is preferably made of a metal such as aluminum, brass, iron or stainless steel. Further, in this case, it is preferable that the bobbin has a large number of holes because the polymerization reaction by-products can be removed quickly and solid phase polymerization can be performed efficiently. Further, when the bobbin is extracted from the fiber package and processed, it is preferable to attach an outer skin to the bobbin outer layer. In any case, it is preferable to wind a cushion material around the outer layer of the bobbin and wind up the liquid crystalline polyester melt-spun fiber on the outer layer of the bobbin in terms of preventing fusion between the innermost layer of the package and the outer layer of the bobbin. . 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 aforementioned outer skin can be substituted with the cushion material.

  The fiber weight of the fiber package may be any weight, but considering the productivity, it is preferably 0.1 kg or more and 20 kg or less. The yarn length is preferably in the range of 10,000 m to 2 million m.

  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 core materials. Therefore, it is preferable to carry out in a nitrogen atmosphere. At this time, the atmosphere of the solid phase polymerization is preferably a low-humidity gas having a dew point of −40 ° C. or less.

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

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

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

  In the production method of the present invention, in order to improve the processability of the fiber, it is preferable that the inorganic particles (A) and the phosphate compound (B) are attached. It is preferable not to wash aggressively. In particular, the condensed salt of inorganic particles and phosphate after solid-phase polymerization is easily washed away with water, so it is preferable not to wash with water during the fiber production process.

Next, the liquid crystal polyester fiber of the present invention will be described in detail.
The liquid crystalline polyester fiber of the present invention is obtained by solid-phase polymerization after applying inorganic particles (A) and a phosphoric acid compound (B) to a yarn obtained by melt spinning a liquid crystalline polyester, The requirements for the manufacturing method are as described above.

  When the total fineness of the liquid crystalline polyester fiber of the present invention is excessively small, the process passability is deteriorated, preferably 5 dtex or more, more preferably 20 dtex or more, and further preferably 50 dtex or more. The total fineness mentioned here is a value obtained by the technique described in the examples. Moreover, when the total fineness is excessively large, when used as a product, the cleaning properties of the inorganic particles in the yarn and the condensed salt of the phosphate deteriorate, and the post-processability deteriorates because the deposit remains, so that it is 5000 dtex or less. Is preferably 3000 dtex or less, and more preferably 1000 dtex or less.

  The single fiber fineness of the liquid crystal polyester fiber of the present invention is preferably 18.0 dtex or less. The single fiber fineness referred to here is a value obtained by the method described in the examples. By reducing the fineness of the single fiber to 18.0 dtex or less, the bending moment of the fiber is reduced and supple, so that it is excellent in process passability and the surface area is increased, so that the amount of resin and chemical solution attached can be increased. It has the characteristics that it is excellent in workability. The single fiber fineness is more preferably 10.0 dtex or less, and even more preferably 7.0 dtex or less. The lower limit of the single fiber fineness is not particularly limited, but the lower limit that can be achieved by this method is about 1.0 dtex.

  The number of single yarns contained in the yarn, that is, the number of filaments, is preferably 1 or more, more preferably 5 or more, still more preferably 10 or more, and most preferably 100 or more. By increasing the number of filaments, even when the single fiber fineness is small, the total fineness can be increased, and the yarn has the flexibility and high strength (product of strength and total fineness), and thus has excellent processability. If the number of filaments is excessively large, the handleability is inferior, so the upper limit is about 5000.

  The strength of the liquid crystalline polyester fiber of the present invention is preferably 15.0 cN / dtex or more, more preferably 18.0 cN / dtex or more, in order to prevent thread breakage in a high-order processing step and increase process passability, and more preferably 20.0 cN / d dtex or more is more preferable. The upper limit of the strength is about 40 cN / dtex in the present invention. In the present invention, the strength is increased by solid-phase polymerization of the fiber obtained by melt spinning.

  The elongation of the liquid crystalline polyester fiber of the present invention is preferably 1.0% or more, and more preferably 2.0% or more in order to prevent yarn breakage in a high-order processing step and increase process passability. The upper limit of elongation is about 5.0% in the present invention. In the present invention, the elongation is increased by solid-phase polymerization of the fiber obtained by melt spinning.

  The elastic modulus of the liquid crystalline polyester fiber of the present invention is preferably 600 cN / dtex or more, more preferably 700 cN / dtex or more, and even more preferably 900 cN / dtex or more in order to prevent yarn breakage in a high-order processing step and increase process passability. . The upper limit of the elastic modulus is about 1500 cN / dtex in the present invention. In the present invention, the elastic modulus is increased by solid-phase polymerization of the fiber obtained by melt spinning.

In the present invention, the strength, elongation, and elastic modulus are values obtained by the method described in the examples.
The liquid crystalline polyester fiber of the present invention has a polystyrene equivalent weight molecular weight of preferably 155,000 or more, more preferably 207,000 or more, and even more preferably 255,000 or more. By setting the molecular weight to 155,000 or more, high strength, elongation, and elastic modulus can be obtained, and the process passability is excellent. The upper limit of the molecular weight is not particularly defined, but the molecular weight that can be reached in the present invention is about 500,000. Here, the weight average molecular weight in terms of polystyrene refers to a value measured by the method described in the examples. In the present invention, the molecular weight can be increased by performing solid phase polymerization in a fiber state.

  In the fiber of the present invention, the heat of fusion (ΔHm1) at the endothermic peak (Tm1) observed when the temperature is measured at 50 ° C. to 20 ° C./min in differential calorimetry is Tm1 + 20 ° C. after the observation of Tm1. After being held at temperature for 5 minutes, it is once cooled to 50 ° C. under a temperature drop condition of 20 ° C./min, and the heat of fusion (ΔHm 2) at the endothermic peak (Tm 2) observed when measured again under a temperature rise condition of 20 ° C./min. ) Is preferably 3.0 times or more, more preferably 4.0 times or more, and even more preferably 6.0 times or more.

  In this measurement method, ΔHm1 represents the degree of crystallization of the fiber (crystallinity), and ΔHm2 represents the degree to which the liquid crystal polyester constituting the fiber is crystallized in the process of re-heating after being once melted and cooled and solidified. When ΔHm1 is 3.0 times or more than ΔHm2, the degree of crystallinity of the fiber is sufficiently high, and high strength and elastic modulus can be obtained. However, if the crystallinity is excessively high, the toughness of the fiber is impaired and the workability is deteriorated. Therefore, ΔHm1 is preferably 15.0 times or less than ΔHm2. In the liquid crystalline polyester fiber of the present invention, there is one endothermic peak at the time of temperature increase and re-temperature increase under the above-described measurement conditions, but two or more peaks are observed depending on the structural change due to the solid phase polymerization conditions and the like. May be. In this case, ΔHm1 is a value obtained by summing the heat of fusion of all endothermic peaks in the temperature raising process, and ΔHm2 is a value obtained by summing the heat of fusion of all endothermic peaks in the reheating temperature process. In the present invention, by applying solid phase polymerization, ΔHm1 is greatly increased, and the strength and elastic modulus are increased. As a result, ΔHm1 / ΔHm2 also increases.

  The absolute value of ΔHm1 varies depending on the composition of the structural unit of the liquid crystal polyester, but is preferably 5.0 J / g or more, more preferably 6.0 J / g or more, and even more preferably 7.0 J / g or more. As ΔHm1 is larger, the degree of crystallinity is higher, the strength and elastic modulus of the fiber is increased, and the heat resistance is improved, so that the process passability can be improved, and in particular, the process passability when the single fiber fineness is reduced can be improved. . The upper limit of ΔHm1 is not particularly limited, but the upper limit that can be achieved in the present invention is about 20 J / g.

  Further, the fiber of the present invention preferably has a peak half width at Tm1 of less than 15 ° C, more preferably 13 ° C or less. The peak half width in this measurement method represents the completeness of the crystal, and it can be said that the smaller the full width at half maximum, the higher the completeness of the crystal. The high crystal perfection increases the strength and elastic modulus of the fiber and improves the heat resistance, so that the process passability can be improved, and in particular, the process passability when the single fiber fineness is reduced can be improved. The lower limit of the peak half-value width is not particularly limited, but the lower limit that can be achieved in the present invention is about 3 ° C. In the present invention, the peak half-value width of Tm1 is reduced by solid-phase polymerization of the fiber obtained by melt spinning.

  The melting point (Tm1) of the fiber of the present invention is preferably 300 ° C. or higher, more preferably 310 ° C. or higher, and further preferably 320 ° C. or higher. Since it has such a high melting point, heat resistance and thermal dimensional stability are excellent, so that it can be processed at a high temperature even after it is made into a product, and post-processability is excellent. The upper limit of Tm1 is not particularly limited, but the upper limit that can be reached in the present invention is about 400 ° C. In the present invention, the absolute value of Tm1 is increased by solid-phase polymerization of the fiber obtained by melt spinning.

  The fibers obtained by the present invention preferably have a condensed salt of inorganic particles and phosphate adhered to the surface. By coating the surface of the fiber with salt and particles that are powder, the running resistance is reduced by the action of powder release, and fibrillation due to fiber abrasion can be prevented, so that the process passability is increased and water is added. Both can be easily washed and removed, so washing with water when making the product can create a state where there is virtually no deposit on the fiber surface, and can improve the adhesion to chemicals and resins, post-processing Excellent in properties. The total amount of these adhering amounts to the fibers is preferably more than 3.0% by weight in order to improve process passability. Moreover, since the efficiency of washing | cleaning removal will fall when there is too much adhesion amount, 20 weight% or less is preferable.

  The liquid crystal polyester fiber of the present invention has characteristics of solid phase polymerized liquid crystal polyester fiber such as high strength and high elastic modulus, and is excellent in process passability and excellent in post-processing properties when used as a product. For this reason, it is widely used in the fields of general industrial materials, civil engineering or building materials, sports applications, protective clothing, rubber reinforcement materials, electrical materials, acoustic materials, general clothing and the like. Effective applications include tension members, resin / rubber reinforcements, screen cages, filters, ropes, nets, fishnets, computer ribbons, printed circuit board fabrics, canvas for papermaking, airbags, airships, domes, etc. , Rider suits, fishing lines, various lines (yachts, paragliders, balloons, kites), blind cords, support cords for screen doors, various cords for cars and aircraft, power transmission cords for electrical products and robots, etc. Applications include tension members that impregnate fibers with resin and chemicals, resin and rubber reinforcements, and base fabrics.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each characteristic value in an Example was calculated | required with the following method.

A. The total fineness and the single fiber fineness measuring machine were used to remove 100 m of fiber, the weight (g) was multiplied by 100, the measurement was performed three times per level, and the average value was defined as the total fineness (dtex). The quotient obtained by dividing this by the number of filaments was defined as the single fiber fineness (dtex).

B. In accordance with the method described in JIS L1013: 1999, the strength, elongation, and elastic modulus are measured 10 times per level using Tensilon UCT-100 manufactured by Orientec Co., Ltd. under the conditions of a sample length of 100 mm and a tensile speed of 50 mm / min. The average value was defined as strength (cN), strength (cN / dtex), elongation (%), and elastic modulus (cN / dtex). The elastic modulus is the initial tensile resistance.

C. Fibers with an adhesion rate of 100 mg or more with respect to the fiber weight were collected, and the weight after drying at 60 ° C. for 10 minutes was measured (W0), and the weight of sodium dodecylbenzenesulfonate in 100 times or more of the fiber weight was measured. The fiber was immersed in a solution with 2.0% by weight added to it, ultrasonically washed at room temperature for 20 minutes, the washed fiber was washed with water, and the weight after drying at 60 ° C. for 10 minutes was measured ( W1) The oil adhesion rate was calculated by the following equation.
(Adhesion rate (% by weight)) = (W0−W1) × 100 / W1
D. Thermal characteristics (Tm1, Tm2, Tm1 peak half width, ΔHm1 / ΔHm2)
DSC2920 manufactured by TA instruments is used for differential calorimetry, the temperature of the endothermic peak observed when the temperature is increased from 50 ° C. to 20 ° C./min is Tm1 (° C.), and the heat of fusion at Tm1 is ΔHm1 ( J / g). After observing Tm1, hold at a temperature of Tm1 + 20 ° C. for 5 minutes, then cool down to 50 ° C. under a temperature drop condition of 20 ° C./min, and endothermic peak observed when measuring again under a temperature rise condition of 20 ° C./min. Was Tm2, and the heat of fusion at Tm2 was ΔHm2 (J / g). The same measurement was performed for the fiber and the resin.

E. Polystyrene equivalent weight average molecular weight (molecular weight)
A mixed solvent of pentafluorophenol / chloroform = 35/65 (weight ratio) was used as a solvent, and the solution was dissolved so that the concentration of liquid crystal polyester was 0.04 to 0.08 weight / volume% to obtain a sample for GPC measurement. In addition, when there was an insoluble matter even after standing at room temperature for 24 hours, the mixture was left still for 24 hours, and the supernatant was used as a sample. This was measured using a GPC measuring apparatus manufactured by Waters, and the weight average molecular weight (Mw) was determined by polystyrene conversion.
Column: 2 Shodex K-806M, 1 K-802 Detector: Differential refractive index detector RI (type 2414)
Temperature: 23 ± 2 ° C
Flow rate: 0.8 mL / min Injection volume: 200 μL
F. Median diameter (D50)
The particle size was measured with a Shimadzu laser diffraction particle size distribution analyzer SALD-2000, and the median diameter (D50) was determined.

G. Fusing suppression effect The package after solid-phase polymerization is fitted into a free-roll creel (having a shaft and a bearing, the outer layer part can rotate freely. There is no brake and drive source), and the yarn is transverse (fiber wrapping direction) from here The surface of the solid-phase polymerization package after being unwound at 400 m / min for 30 minutes was observed, and the fusing suppression effect was evaluated according to the following criteria based on the presence or absence of fluff.
A: No fluff is seen.
○: 1 to 2 fluffs are observed.
X: 3 or more fluffs are seen.

H. After unwinding the process-passable liquid crystal polyester fiber, the first roller with a separate roller rotating at 400 m / min is rotated 6 times, and subsequently the second roller with a separate roller rotating at 401 m / min is rotated 6 times Aspirated with a suction gun. After this operation was performed for 30 minutes, the passability of the process was evaluated according to the following criteria from the number of yarn swaying in the running state for 1 minute (the number of times the running yarn was likely to be taken by the roller).
◎: Yarn swing 0 times ○: Yarn swing 2 times or less ×: Yarn swing 3 times or more

I. Post-processability The fiber after measuring the adhesion rate with respect to the fiber weight is observed using an optical microscope, the surface of five single fibers in the same field of view, and the post-processability is evaluated from the adherence of the fiber surface according to the following criteria did.
A: 2 or less deposits on the fiber surface B: 3 to 10 deposits on the fiber surface X: 11 or more deposits on the fiber surface

Reference example 1
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4′-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid Then, 1460 parts by weight of acetic anhydride (1.10 equivalents of total phenolic hydroxyl groups) was added, and the temperature was raised from room temperature to 145 ° C. over 30 minutes with stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 335 degreeC in 4 hours.
The polymerization temperature was maintained at 335 ° C., the pressure was reduced to 133 Pa in 1.5 hours, and the reaction was continued for another 40 minutes. When the torque reached 28 kgcm, the polycondensation was completed. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.
The composition, melting point and molecular weight of the obtained liquid crystal polyester are as shown in Table 1.

Reference example 2
In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 907 parts by weight of p-hydroxybenzoic acid, 457 parts by weight of 6-hydroxy-2-naphthoic acid and 946 parts by weight of acetic anhydride (1. 03 molar equivalents) was charged into a reaction vessel equipped with a stirring blade and a distillation tube, and the temperature was raised from room temperature to 145 ° C. over 30 minutes while stirring in a nitrogen gas atmosphere, followed by reaction at 145 ° C. for 2 hours. Then, it heated up to 325 degreeC in 4 hours.
The polymerization temperature was maintained at 325 ° C., the pressure was reduced to 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 0.1 MPa, the polymer was discharged to a strand through a die having one circular discharge port having a diameter of 10 mm, and pelletized by a cutter.
The composition, melting point and molecular weight of the obtained liquid crystal polyester are as shown in Table 1.

Example 1
After performing vacuum drying at 160 ° C. for 12 hours using the liquid crystalline polyester of Reference Example 1, the polymer was supplied to the spinning pack while being melt extruded using a φ15 mm twin-screw extruder manufactured by Techno Bell Co., Ltd. and measured with a gear pump. In the spinning pack, the polymer was filtered using a metal nonwoven fabric filter, and the polymer was discharged under the conditions shown in Table 2. The introduction hole located immediately above the die hole was a straight hole, and the connection portion between the introduction hole and the die hole was tapered. The discharged polymer is allowed to pass through a 40 mm heat retaining region, and then cooled and solidified from the outside of the yarn with an annular cooling air flow at 25 ° C., and then a spinning oil mainly composed of a fatty acid ester compound is applied, All filaments were taken up on the first godet roll at the spinning speeds listed in Table 2. After passing this through the second godet roll at the same speed, all but one of the filaments is sucked with a suction gun, and the remaining one-filament fiber is a PAN winder (EFT type manufactured by Kozu Manufacturing Co., Ltd.). It was wound up in the shape of a pan with a take-up winder and no contact roll in contact with the winding package. During winding, yarn breakage did not occur, and the yarn forming property was good. The obtained spinning fiber properties are shown in Table 2.

  The spun fiber package was rewound using an SSP-MV type rewinder (contact length 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), without using a speed control roller, but using an oiling roller (satin-finished stainless steel roll) as a phosphate compound (B) (4)

In an aqueous solution containing 6.0% by weight of the phosphoric acid compound (B ₁ ) represented by the formula, talc shown as talc 1 in Table 3 as inorganic particles (A), SG-2000 (manufactured by Nippon Talc Co., Ltd.) The oil for solid phase polymerization dispersed at 0% by weight was supplied. As the core material for rewinding, a bobbin made of stainless steel wound with Kevlar felt (weight per unit area 280 g / m ² , thickness 1.5 mm) was used, and the surface pressure was 100 gf. Table 3 shows the oil adhesion rate of the solid-phase polymerization oil to the fiber after rewinding and the rewinding conditions.

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

  The package after solid-phase polymerization is fitted into a freeroll creel (having a shaft and a bearing, the outer layer part can freely rotate. There is no brake and drive source), and the yarn is pulled out in the lateral direction (fiber circulation direction) from here. After making it rotate 6 times by the 1st roller with a separate roller rotating at 400 m / min, it wound up with the EFT type | mold bobbin traverse winder (made by Kozu Seisakusho). Table 3 shows the fiber properties after solid phase polymerization obtained.

  The results of property evaluation of the obtained fiber are also shown in Table 3, and it can be seen that the fusion suppressing effect, process passability, and post-processability are excellent.

Examples 2 and 3
Here, the influence of the adhesion rate of the oil for solid phase polymerization was evaluated.
Example 1 except that melt spinning was performed in the same manner as in Example 1 to obtain a spun fiber, the number of rotations of the oiling roller during rewinding was changed, and the adhesion rate of the solid-phase polymerization oil was changed as shown in Table 3. In the same manner, it was rolled up and subjected to solid phase polymerization to obtain liquid crystal polyester fibers. Table 3 shows the fiber properties after solid phase polymerization obtained.
Table 3 also shows the evaluation results of the properties of the obtained fibers. Although the fusion suppression effect, process passability, and post-processability are excellent, the adhesion amount in Example 2 is small, so the fusion suppression effect, process passability, and post-processability are slightly inferior, and in Example 3, the adhesion amount is large. It can be seen that the post-processability is slightly inferior.

Examples 4 and 5
Here, the influence of the inorganic particles (A) was evaluated.
A liquid crystal polyester fiber was obtained in the same manner as in Example 1 except that Silicia 310P (manufactured by Fuji Silysia Chemical Co., Ltd.), which is silica, was used as the inorganic particles (A) (Example 4). Further, liquid crystal polyester fibers were obtained in the same manner as in Example 1 except that talc and microace P-2 (manufactured by Nippon Talc Co., Ltd.) shown as talc 2 in Table 3 were used as the inorganic particles (A). Table 3 shows the fiber properties after solid phase polymerization obtained.
Table 3 also shows the evaluation results of the properties of the obtained fibers. Although the fusion suppressing effect, process passability, and post-processability are excellent, it can be seen that as the median diameter increases, the fusion suppression effect, process passability, and post-processability are slightly deteriorated.

Examples 6 and 7
Here, the influence of the weight ratio between the inorganic particles (A) and the phosphoric acid compound (B) was evaluated.
A liquid crystal polyester fiber was obtained in the same manner as in Example 1 except that the dispersion amount of the inorganic particles (A) in the solid-phase polymerization oil agent was changed and the adhesion rate (a) of the inorganic particles to the fibers was changed as shown in Table 3. . Table 3 shows the fiber properties after solid phase polymerization obtained.
Table 3 also shows the evaluation results of the properties of the obtained fibers. Although the fusion suppressing effect, process passability and post-processability are excellent, the post-processability is slightly higher when (b / a) is small, and the process passability and post-processability is slightly higher when (b / a) is lower. It turns out that it gets worse.

Examples 8 and 9
Here, the influence of the phosphoric acid compound (B) was evaluated.
Example 1 except that the phosphoric acid compound (B) was changed to a phosphoric acid compound (B ₂ ) represented by the following chemical formula (5) and a phosphoric acid compound (B ₃ ) represented by the following chemical formula (6). In the same manner as above, a liquid crystal polyester fiber was obtained. Table 3 shows the fiber properties after solid phase polymerization obtained. Molecular weight other values B ₂ in solid phase polymerization as can be seen from the are not in slightly advances, a tendency to proceed in B _3.

Table 3 also shows the evaluation results of the properties of the obtained fibers. Although fusion suppression effect, process passability, and post-processability are excellent, B ₂ is slightly inferior in post-processability due to a large amount of oxygen-containing hydrocarbon groups, and B ₃ is a little inferior in post-processability. It turns out that it is somewhat inferior to the adhesion suppression effect and process passability.

Comparative Examples 1-5
Here, the effect of using the inorganic particles (A) and the phosphoric acid compound (B) in combination was evaluated.
In Comparative Examples 1 and 2, only inorganic particles (A) were used as the oil for solid-phase polymerization, and no phosphoric acid compound (B) was used. In Comparative Example 1, the concentration of inorganic particles (A) was changed to Example 1. The solid phase polymerization was carried out in the same manner as in Example 1 except that 2.0% by weight was used in Comparative Example 2. In Comparative Example 1, the fibers were fused together, and fibrils were frequently generated during unwinding, so fibers after solid phase polymerization were not obtained. In Comparative Example 2, fibers after solid phase polymerization could be obtained, but a large amount of fluff was observed on the surface of the package. From this, it can be seen that the inorganic particles alone are insufficient in the effect of suppressing fusion.
In Comparative Example 3, an aqueous dispersion of polydimethylsiloxane (PDMS) was used instead of the phosphoric acid compound (B) as an oil agent for solid-phase polymerization, and in Comparative Example 4, only the phosphoric acid compound was used without using inorganic particles. In Comparative Example 5, a liquid crystalline polyester was used in the same manner as in Example 1 except that only the polydimethylsiloxane dispersion was used, the number of rotations of the oiling roller was adjusted, and the amount of solid phase polymerization oil was changed as shown in Table 4. Fiber was obtained. Table 4 shows the fiber properties after solid phase polymerization obtained.
Table 4 also shows the evaluation results of the properties of the obtained fibers. It can be seen that Comparative Example 2 is inferior in the fusion suppressing effect and post-workability. In Comparative Example 3, an excellent fusion suppressing effect is exhibited by the combined use of inorganic particles and polysiloxane, but it can be seen that there are many deposits on the fiber surface and the post-processability is poor. Further, in Comparative Example 4, since only the phosphoric acid compound is used, the effect of suppressing fusion is inferior, and the phosphate is hygroscopic, deliquescent and has viscosity, so that the process passability is inferior. In Comparative Example 5, it can be seen that the use of only polysiloxane is inferior in process passability and post-processability.

Examples 10-14
Here, the influence of the spun fiber was evaluated.
Except for changing the spinning conditions such as the liquid crystal polyester polymer, spinning temperature and the like as shown in Table 2, melt spinning was performed in the same manner as in Example 1 to obtain a spun fiber. In Example 14, only one of the yarns discharged from the four-hole cap was wound up, and the rest was removed by suction with a suction gun. The obtained fiber physical properties are also shown in Table 2. In Example 10 using the polymer of Reference Example 2 and Example 12 in which spinning was performed at a single yarn fineness of 4.8 dtex, yarn breakage occurred during spinning.

  Using the obtained spun fiber, it was wound and solid phase polymerization was performed in the same manner as in Example 1 except that the winding conditions and the solid phase polymerization conditions were changed as shown in Table 4. In Example 13, three spinning fibers were combined and wound back. Table 4 shows the fiber properties after solid phase polymerization obtained.

  Table 4 also shows the evaluation results of the properties of the obtained fibers. Although there are differences due to the difference in the spun fibers, it can be seen that the fusion suppressing effect, process passability and post-processability are excellent.

Claims (2)

A method for producing a liquid crystal polyester fiber, comprising applying inorganic particles (A) and a phosphoric acid compound (B) to a yarn obtained by melt spinning a liquid crystal polyester, followed by solid phase polymerization. A liquid crystal polyester fiber obtained by the production method according to claim 1.