JP4634526B1 - Polyester fiber and method for producing the same - Google Patents

Abstract

The present invention provides a polyester fiber that has few defects such as voids caused by catalyst particles and the like, and has little variation in physical properties and generation of fluff.
A polyester fiber comprising metal-phosphorous layered nanoparticles having a side length of 5 to 100 nm and an interlayer spacing of 1 to 5 nm. Furthermore, the metal element in the layered nanoparticle is a divalent metal, or the divalent metal is selected from the group consisting of a metal element of Group 4 to 5 and Group 3 to 12 in the periodic table and Mg. It is preferable that it is one or more metal elements, and that the divalent metal is at least one metal element selected from the group consisting of Zn, Mn, Co, and Mg. Furthermore, it is preferable that the metal-phosphorus compound constituting the layered nanoparticle is a phenylphosphonic acid derivative.
[Selection] Figure 1

Description

  The present invention relates to a high-strength polyester fiber useful as a reinforcing fiber for industrial materials and the like, in particular, a fiber / polymer composite, and a method for producing the same.

  Polyester fibers have many excellent properties such as high strength, high Young's modulus, and heat-resistant dimensional stability, and are therefore used in a wide range of fields such as clothing and industrial use. It is known that the physical properties of this polyester fiber vary greatly depending on the type of catalyst for the polymer polycondensation reaction.

  For example, as a polycondensation catalyst for polyethylene terephthalate fibers, antimony compounds are widely used because they have an excellent polycondensation catalyst function. Patent Document 1 and the like describe an example in which a specific phosphorus compound is added. Patent Document 2 describes an example using a reaction product of a titanium compound and a phosphorus compound.

  However, even when any catalyst is used, although the effect of improving the spinning property is seen, the effect is insufficient and further improvement of the spinning property has been demanded. In addition, since the fiber properties obtained vary in response to the poor yarn-making properties, development of higher-performance polyester fibers has been demanded.

JP-A-62-206018 JP 2002-293909 A

  It is an object of the present invention to provide a polyester fiber that has few defects such as voids caused by catalyst particles and the like, and has little variation in physical properties and generation of fluff.

The polyester fiber of the present invention is a fiber made of polyester, which is composed of a divalent metal and a phosphorus compound, has a side length of 5 to 100 nm, and an interlayer spacing of 1 to 5 nm. It is characterized by including.

Furthermore, the divalent metal which is a metal element in the layered nanoparticle is at least one metal element selected from the group consisting of a metal element of Group 4 to 5 and Group 3 to 12 and Mg in the periodic table. It is preferable that the divalent metal is at least one metal element selected from the group consisting of Zn, Mn, Co, and Mg.

  Further, the metal-phosphorus compound constituting the layered nanoparticles is derived from the phosphorus compound represented by the following general formula (I), and further the metal-phosphorus compound constituting the layered nanoparticles is phenylphosphonic acid. A derivative is preferred.

(In the above formula, Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, R ¹ represents a hydrogen atom or OH group, R ² represents a hydrogen atom, or unsubstituted or substituted. Represents a hydrocarbon group having 1 to 20 carbon atoms.)

Moreover, it is preferable that content of the metal and phosphorus in polyester satisfy | fills the following (III) Formula and (IV) Formula.
10 ≦ M ≦ 1000 (III)
0.8 ≦ P / M ≦ 2.0 (IV)
(In the formula, M represents mmol% of the metal element with respect to the dicarboxylic acid component constituting the polyester, and P represents mmol% of the phosphorus element.)

  The main repeating unit of polyester of the polyester fiber of the present invention is selected from the group consisting of ethylene terephthalate, ethylene-2,6-naphthalate, trimethylene terephthalate, trimethylene-2,6-naphthalate, butylene terephthalate, butylene-2,6-naphthalate. It is preferable that the polyester is polyethylene terephthalate, and the polyester preferably has a diffraction peak at 2θ = 5 to 7 ° in the XRD diffraction in the equator direction of the fiber.

Another method for producing a polyester fiber according to the present invention is a method for producing a polyester fiber by melt spinning a polyester containing layered nanoparticles, wherein the layered nanoparticles are composed of a divalent metal and a phosphorus compound, and the shape thereof is The length of one side is 5 to 100 nm, and the interlayer spacing is 1 to 5 nm.

Further, the layered nanoparticles, and this is preferable that the internally precipitated by the addition of divalent metal and phosphorus compound during the production process.

  According to the present invention, there is provided a polyester fiber that has few defects such as voids caused by catalyst particles and the like, and has few variations in physical properties and generation of fluff.

2 is a transmission electron microscope (TEM) photograph of the polyester fiber obtained in Example 1. FIG. In addition, the arrow in a figure shows the fiber axis direction. It is an X-ray-diffraction result of the polyester fiber obtained in Example 1 and Comparative Example 1. The vertical axis represents the diffraction intensity, and the horizontal axis represents the angle 2θ (°).

  As the polyester polymer used in the polyester fiber of the present invention, a general-purpose polyester polymer having excellent properties as a fiber for reinforcing rubber such as industrial materials, particularly tire cords and transmission belts is used. Among them, the main repeating unit of polyester is selected from the group consisting of ethylene terephthalate, ethylene-2,6-naphthalate, trimethylene terephthalate, trimethylene-2,6-naphthalate, butylene terephthalate, butylene-2,6-naphthalate. It is preferable. In particular, it is preferably made of polyethylene terephthalate which has excellent physical properties and is suitable for mass production. As a main repeating unit of polyester, it is preferable that 80 mol% or more of the repeating unit is contained with respect to all dicarboxylic acid components constituting the polyester. Particularly preferred is a polyester containing 90 mol% or more. Moreover, if it is a small amount in the polyester polymer, it may be a copolymer containing an appropriate third component.

  The polyester fiber of the present invention is a fiber made of polyester as described above, and includes metal-phosphorous layered nanoparticles having a side length of 5 to 100 nm and an interlayer spacing of 1 to 5 nm. Required. Furthermore, the layered nanoparticles are preferably a metal-phosphorus compound, and the metal element that is a constituent component of the layered nanoparticles is preferably a divalent metal. Usually, the polyester fiber often includes spherical catalyst particles used as the transesterification catalyst / polycondensation catalyst. In the present invention, the greatest feature is that the shape of the catalyst particles is layered nanoparticles. is there. Although the mechanism of action of the present invention is not clear, the particle shape in the polymer has a layered structure, so that the surface area is larger and the surface energy activity is higher than that of spherical particles, and the action as a crystal nucleating agent is promoted. This is probably because of this. The catalyst fine particles have a microstructure with a side length of 5 to 100 nm and an interlayer spacing of 1 to 5 nm, thereby further improving the crystallinity of the polymer and promoting the homogenization and fine dispersion of the crystal structure. It is considered that the physical properties of the fiber are remarkably improved in order to appropriately suppress the molecular orientation. The catalyst particles at this time are generally metal-containing particles.

  The length of one side of the layered nanoparticle is further preferably 6 to 80 nm, and more preferably 10 to 60 nm. Such layered nanoparticles in the polyester fiber of the present invention can be confirmed by a transmission electron microscope. When the size of the layered nanoparticle is larger than 100 nm, it acts as a foreign substance in the fiber, and breakage or single yarn breakage is likely to occur. It was used for physical properties such as strength and modulus, and for reinforcing fibers such as tires and belts. Even in this case, the durability of the product is reduced. On the other hand, if the particles are too small, it is difficult to obtain the effects of improving the crystallinity of the polymer and improving the yarn production, and the physical properties of the obtained fibers, particularly when used as reinforcing fibers for tires, the durability and the uniform mini When used for tee and belt applications, its durability and dimensional stability are reduced.

  In the present invention, the layered nanoparticles of 100 nm or less are thus contained in the polyester fiber, and the layered nanoparticles are preferably those that are internally precipitated by adding a divalent metal and a phosphorus compound in the polyester. . When normal layered particles such as layered silicate are externally added, the layered particles tend to aggregate, and it is difficult to incorporate such fine particles in the polyester. And in this invention, it is preferable that the magnitude | size of the layered nanoparticle to contain is 100 nm or less, Furthermore, it is only 80 nm or less.

  The interlayer spacing of each layer of the layered nanoparticles is preferably 1 to 5 nm, more preferably 1.5 to 3 nm. If the length of one side of the layered nanoparticle is too long, a defect is noticeable without forming a microstructure. If the length of one side is too small, it becomes difficult to take a layered structure. On the other hand, the interlayer spacing of the layered nanoparticles is preferably 1 to 5 nm, more preferably 1.5 to 3 nm. Here, the interlayer distance is the distance between a layer mainly made of a metal element and a layer made of an element other than that, such as carbon, phosphorus and oxygen. The layered structure is a state where each layer is arranged in parallel with at least 3 layers, preferably 5 to 100 layers. Moreover, it is preferable that the space | interval of each layer is the state which has located in a line at the space | interval of 1/5 or less of the length of each layer in the substantially orthogonal direction of the arrangement | sequence of each layer.

  The polyester fiber of the present invention is required to contain such metal-phosphorous layered nanoparticles, but preferably 50% or more of the particles have a layered structure composed of a metal and a phosphorus compound. 70% or more, most preferably all the particles have a metal-containing layered structure.

  Furthermore, the polyester fiber of the present invention preferably has a diffraction peak at 2θ (theta) = 2 to 7 ° in wide-angle X-ray diffraction (XRD diffraction) diffraction in the equator direction of the fiber. This numerical value indicates that layered nanoparticles having an interlayer spacing on the order of nm are regularly oriented in the fiber axis direction. Thus, by specifically orienting in the fiber axis direction, the polyester fiber of the present invention has a very low yarn breaking rate in the polyester yarn production process. That is, productivity is dramatically improved. Further, the obtained polyester fiber has fewer defects, and its physical properties can be made extremely high. As a result, it became a fiber suitable for reinforcement applications, particularly rubber reinforcement applications such as tire cord applications and belt applications.

  Further, the layered nanoparticles of the present invention must be metal-phosphorous, and the metal element that is a constituent component of the layered nanoparticles is preferably a divalent metal. The metal-phosphorous layered nanoparticles are preferably composed of a divalent metal and a phosphorus compound. Further, the metal element is preferably at least one metal element selected from the group consisting of a metal element of the 4th to 5th period and 3 to 12 group in the periodic table and Mg. Furthermore, the layered nanoparticles are preferably composed of a compound containing at least one metal element selected from the group consisting of Zn, Mn, Co, and Mg. Such a metal element is preferable because it easily constitutes the minute layered nanoparticles of the present invention and has high catalytic activity.

  Furthermore, the layered nanoparticles used in the present invention must be metal-phosphorous, and the phosphorus compound used in the metal-phosphorous layered nanoparticles is represented by the following general formula (I). It is preferably derived from a phosphorus compound.

(In the above formula, Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, R ¹ represents a hydrogen atom or OH group, R ² represents a hydrogen atom, or unsubstituted or substituted. Represents a hydrocarbon group having 1 to 20 carbon atoms.)

  Examples of the compound of the general formula (I) include phenylphosphonic acid, monomethyl phenylphosphonate, monoethyl phenylphosphonate, monopropyl phenylphosphonate, monophenyl phenylphosphonate, monobenzyl phenylphosphonate, (2-hydroxy Ethyl) phenylphosphonate, 2-naphthylphosphonic acid, 1-naphthylphosphonic acid, 2-anthrylphosphonic acid, 1-anthrylphosphonic acid, 4-biphenylphosphonic acid, 4-methylphenylphosphonic acid, 4-methoxyphenylphosphonic acid , Phenylphosphinic acid, methyl phenylphosphinate, ethyl phenylphosphinate, propylphenylphosphinate, phenylphenylphosphinate, benzylphenylphosphinate, (2-hydroxyethyl) phenylphosphine , 2-naphthylphosphinic acid, 1-naphthylphosphinic acid, 2-anthrylphosphinic acid, 1-anthrylphosphinic acid, 4-biphenylphosphinic acid, 4-methylphenylphosphinic acid, 4-methoxyphenylphosphinic acid, etc. be able to.

Incidentally, Ar used in the formula represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, R ¹ represents a hydrogen atom or OH group, R ² represents a hydrogen atom or unsubstituted And hydrocarbon groups having 1 to 20 carbon atoms which are substituted or substituted. Furthermore, the hydrocarbon group for R ² is preferably an alkyl group, an aryl group, or a benzyl group, which may be unsubstituted or substituted. At this time, the substituent of R ² preferably does not inhibit the steric structure. Examples thereof include those substituted with a hydroxyl group, an ester group, an alkoxy group, and the like. The aryl group represented by Ar in the above (I) may be substituted with, for example, an alkyl group, an aryl group, a benzyl group, an alkylene group, a hydroxyl group, or a halogen atom.

  Preferable examples of the aryl group substituted with such a substituent include the following functional groups and isomers thereof.

However, for example, alkyl diesters such as dimethyl phenylphosphonate are not preferable because steric hindrance occurs due to the presence of an alkyl group and a layered structure cannot be formed.
Addition of such a phosphorus compound having an aryl group is preferable because a high crystallinity improving effect tends to appear.

  In particular, the phosphorus compound is most preferably phenylphosphonic acid, phenylphosphinic acid, and derivatives thereof. Of these, phenylphosphonic acid and its derivatives represented by the following formula are effective because they can be used in small amounts. In terms of physical properties, the hue and melt stability of the resulting polyester, the spinning performance, the ability to form high layered nanoparticles, and the like are improved. From the viewpoint of workability, it is excellent in that no by-product is produced in the polyester production process. Particularly preferred is phenylphosphonic acid.

(Wherein Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, R ² represents a hydrogen atom, or an unsubstituted or substituted 1 to 20 carbon atom. The hydrocarbon group which has is shown.)

  Conversely, dialkyl esters such as dimethyl phenylphosphonate that does not have a hydroxyl group have a low boiling point and are likely to be scattered under vacuum, which tends to be undesirable in the present application. When scattered, the amount of the added phosphorus compound remaining in the polyester tends to decrease, and the effect tends not to be obtained. In such a case, the vacuum system tends to be clogged. The dialkyl ester of phosphonic acid has no hydroxyl group and has high scattering properties, so in the spinning process where it is melted and discharged at high temperatures, the phenomenon of liberation and elution from the polymer occurs, and it is easy to form foreign matter fixed to the die. There is. For this reason, it becomes a factor which worsens the stability of the yarn production in a long term, and is not preferable. Further, phosphonic acid dialkyl esters do not have a hydroxyl group directly bonded to phosphorus. For this reason, the ability to deactivate a metal compound such as a transesterification catalyst or a polymerization catalyst is low, which leads to deterioration of the melt stability and hue of the resulting polymer, which is not preferable.

The layered nanoparticles used in the present invention are preferably composed of a metal component and a phosphorus component. In this case, the contents of the metal and phosphorus in the polyester used in the present invention include the following formula (III) and It is preferable that the formula (IV) is satisfied.
10 ≦ M ≦ 1000 (III)
0.8 ≦ P / M ≦ 2.0 (IV)
(In the formula, M represents mmol% of the metal element with respect to the dicarboxylic acid component constituting the polyester, and P represents mmol% of the phosphorus element.)

  When the metal content is too small, the amount of the layered nanoparticles functioning as a crystal nucleating agent is insufficient, and the effect of improving the spinning property tends to be difficult to obtain. On the other hand, if the amount is too large, it tends to remain in the fiber as a foreign substance, resulting in a decrease in physical properties, and a severe thermal deterioration of the polymer. On the other hand, when the P / M ratio represented by the formula (IV) is too small, the metal compound concentration M becomes excessive, and the excess metal atom component accelerates the thermal decomposition of the polyester and significantly deteriorates the thermal stability. On the other hand, when the P / M ratio is too large, the phosphorus compound becomes excessive, and the excessive phosphorus compound component tends to inhibit the polymerization reaction of the polyester and the fiber physical properties tend to decrease. A more preferable P / M ratio is preferably 0.9 to 1.8.

  The polyester fiber of the present invention is characterized by containing the above-mentioned layered nanoparticles. More specifically, the polyester polymer constituting the polyester fiber is obtained by the following production method. It is preferable that

  For example, as the polyester polymer used in the present invention, terephthalic acid, naphthalene-2,6-dicarboxylic acid or a functional derivative thereof can be polymerized in the presence of a catalyst under appropriate reaction conditions. In addition, a copolymerized polyester is synthesized by adding one or more appropriate third components before the completion of polymerization of the polyester.

  Suitable third components include: (a) compounds having two ester-forming functional groups, for example, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid; cyclopropanedicarboxylic acid, Cycloaliphatic dicarboxylic acids such as cyclobutane dicarboxylic acid and hexahydroterephthalic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene-2,7-dicarboxylic acid, diphenyldicarboxylic acid; diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, Carboxylic acids such as diphenoxyethanedicarboxylic acid and sodium 3,5-dicarboxybenzenesulfonate; oxycarboxylic acids such as glycolic acid, p-oxybenzoic acid, p-oxyethoxybenzoic acid; propylene glycol, trimethylene glycol, and diethyl Glycol, tetramethylene glycol, hexamethylene glycol, neopentylene glycol, p-xylylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, p, p'-diphenoxysulfone-1,4-bis (β- Hydroxyoxy) benzene, 2,2-bis (p-β-hydroxyethoxyphenyl) propane, polyalkylene glycol, oxy compounds such as p-phenylenebis (dimethylcyclohexane), or functional derivatives thereof; carboxylic acids, oxycarboxylic Compounds having a high degree of polymerization derived from acids, oxy compounds or functional derivatives thereof, and (b) compounds having one ester-forming functional group such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, methoxy Polyalkyle Glycol and the like. Furthermore, (c) compounds having three or more ester-forming functional groups, such as glycerin, pentaerythritol, trimethylolpropane, tricarballylic acid, trimesic acid, trimellitic acid, etc., are substantially linear in polymer. It can be used within the range.

  In the polyester, various additives such as matting agents such as titanium dioxide, heat stabilizers, antifoaming agents, color modifiers, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, fluorescent agents Additives such as montmorillonite, bentonite, hectorite, plate-like iron oxide, plate-like calcium carbonate, plate-like boehmite, or carbon nanotubes are included as additives for whitening agents, plasticizers, impact agents, or reinforcing agents. It goes without saying.

  More specifically, a method for producing a polyester polymer used in the present invention can be described as a conventionally known method for producing a polyester polymer. That is, as a production method, first, as an acid component, transesterification is performed between a dialkyl ester of a dicarboxylic acid represented by dimethyl terephthalate (DMT) or naphthalene-2,6-dimethylcarboxylate (NDC) and ethylene glycol as a glycol component. React. Thereafter, the product of this reaction is heated under reduced pressure to perform polycondensation while removing excess diol components. Alternatively, it can also be produced by esterification with terephthalic acid (TA) or 2,6-naphthalenedicarboxylic acid as an acid component and ethylene glycol as a diol component by a conventionally known direct polymerization method.

  As the transesterification catalyst used in the case of the method utilizing transesterification, it is efficient to use the metal constituting the layered nanoparticles, but other metals may be used. In general, manganese, magnesium, titanium, zinc, aluminum, calcium, cobalt, sodium, lithium, lead compounds, and the like can be used. Examples of the catalyst compound include manganese, magnesium, titanium, zinc, aluminum, calcium, cobalt, sodium, lithium, lead oxide, acetate, carboxylate, hydride, alcoholate, halide, carbonate, sulfuric acid. A salt etc. can be mentioned.

  Among these, manganese, magnesium, zinc, titanium, and cobalt compounds are preferable from the viewpoints of the melt stability of polyester, the hue, the small amount of insoluble foreign matter in the polymer, and the stability of spinning. Further, manganese, magnesium and zinc compounds are preferable. Two or more of these compounds may be used in combination.

  As for the polymerization catalyst, antimony, titanium, germanium, and an aluminum compound are preferable. Examples of such compounds include antimony, titanium, germanium, aluminum oxides, acetates, carboxylates, hydrides, alcoholates, halides, carbonates, sulfates, and the like. Moreover, these compounds may use 2 or more types together.

  Of these, antimony compounds are particularly preferred. This is because the polyester has excellent polymerization activity, solid-phase polymerization activity, melt stability, and hue, and the resulting fiber has high strength and excellent spinning properties and stretchability.

  In the method of directly esterifying an aromatic dicarboxylic acid component such as terephthalic acid and a glycol component such as ethylene glycol, the transesterification catalyst as described above and the catalyst in the direct esterification reaction are originally It is unnecessary. However, in order to express the effects of the present invention, it is necessary to include a catalyst component that can form layered nanoparticles. The content of the metal component in the catalyst is preferably in the range of 10 to 1000 mmol% with respect to all repeating units constituting the polyester.

  In addition, in the present invention, the layered nanoparticles are finally contained in the polyester, but as the layered nanoparticles, by adding a metal and a phosphorus compound from outside the system at any stage of producing the polyester polymer, It is preferable that they are precipitated internally.

  As a method for producing the polyester fiber of the present invention, the layered nanoparticles in the polyester used in the production method of the present invention are preferably produced by adding a metal element and a phosphorus compound to the polyester, Thus, when the layered nanoparticles are precipitated internally, the fine dispersion of the layered nanoparticles can be further promoted compared to the case where the layered nanoparticles are added from the outside, and the performance of the resulting fiber is improved. It is also one of preferred embodiments that a polyester master polymer containing such layered nanoparticles in high concentration is prepared in advance and diluted with a polyester base polymer.

  More specifically, in the case of a production method in which an esterification reaction is performed with a dicarboxylic acid component and a diol component, the metal and the phosphorus compound are added at any stage from the esterification reaction to immediately before the yarn production, and the layered nanoparticles are added to the interior of the polyester. Can be deposited.

  In the case of a production method in which a dialkyl ester of a dicarboxylic acid and a diol component are subjected to an ester exchange reaction, the metal and the phosphorus compound are added at any stage from the ester exchange reaction to immediately before the yarn production, and the layered nanoparticles are precipitated inside the polyester. Can be made. More preferably, the metal and the phosphorus compound are added before the polycondensation is completed. This is because after the polycondensation, the viscosity of the polymer is high and it is difficult to uniformly and uniformly disperse the metal and / or phosphorus compound.

  Note that the addition order of the metal and the phosphorus compound may be simultaneous, separate, or whichever comes first. Preferably, it is possible to present a method in which one of the two components is added first and sufficiently dispersed using a stirrer or the like, and then the other is added. This method makes it possible to suppress aggregation of the layered nanoparticles. However, in the case of the production method by transesterification, since there is a problem of reaction inhibition described later, it is necessary to pay attention to the addition timing of the phosphorus compound. The metal is preferably a divalent metal.

In order to produce layered nanoparticles, it is preferable to add a phosphorus compound to polyester in which a metal as a catalyst component exists. As content in the polyester polymer of this phosphorus compound, the range satisfy | filling following Formula is suitable.
0.8 ≦ P / M ≦ 2.0 (IV)
(In the formula, M represents mmol% of the metal element with respect to the dicarboxylic acid component constituting the polyester, and P represents mmol% of the phosphorus element.)

  When the P / M ratio represented by the formula (IV) is too small, the metal compound concentration M becomes excessive, and the excess metal atom component accelerates the thermal decomposition of the polyester and remarkably impairs the thermal stability. On the other hand, when the P / M ratio is too large, the phosphorus compound becomes excessive, and the excessive phosphorus compound component tends to inhibit the polymerization reaction of the polyester and the fiber physical properties tend to decrease. A more preferable P / M ratio is preferably 0.9 to 1.8.

  The addition time of this phosphorus compound is not particularly limited. It can be added at any step of the polyester production. Preferably, the polymerization is completed from the beginning of the transesterification or esterification reaction. More preferably, it is between the time when the transesterification or esterification reaction is completed and the time when the polymerization reaction is completed. Particularly in the case of transesterification, it is preferable to add a phosphorus compound after completion of the transesterification. In the addition before the transesterification reaction, the transesterification reaction is inhibited by the phosphorus compound, which may cause problems such as a decrease in productivity and a deterioration in the hue of the resulting polyester polymer.

  Alternatively, a method of kneading the phosphorus compound using a kneader after polymerization of the polyester can also be employed. The method of kneading is not particularly limited, but it is preferable to use a normal uniaxial or biaxial kneader. More preferably, in order to suppress a decrease in the degree of polymerization of the resulting polyester composition, a method of using a vented uniaxial or biaxial kneader can be exemplified.

  The conditions at the time of kneading are not particularly limited. For example, the melting point is higher than the melting point of the polyester, and the residence time is 1 hour or less, and more preferably 1 minute to 30 minutes. Moreover, the supply method of the phosphorus compound and polyester to a kneading machine is not specifically limited. Examples thereof include a method of separately supplying a phosphorus compound and polyester to a kneader, and a method of appropriately mixing and supplying a master chip containing a high concentration phosphorus compound and polyester.

  The polyester polymer used in the present invention that has been polymerized in this way has an intrinsic viscosity of the resin chip immediately before spinning of 0.80-1. In the case of 20, polyethylene naphthalate, the range of 0.65 to 1.2 is preferable. If the intrinsic viscosity of the resin chip is too low, it is difficult to increase the strength of the fiber after melt spinning. On the other hand, if the intrinsic viscosity is too high, the solid-state polymerization time is greatly increased and the production efficiency is lowered, which is not preferable from the industrial viewpoint. The intrinsic viscosity is preferably in the range of 0.9 to 1.1 for polyethylene terephthalate and 0.7 to 1.0 for polyethylene naphthalate, respectively.

The polyester fiber of the present invention can be produced by melt spinning the polyester polymer containing the layered nanoparticles thus obtained.
That is, another method for producing a polyester fiber according to the present invention is a method for producing a polyester fiber by melt spinning a polyester containing layered nanoparticles, wherein the layered nanoparticles are composed of a metal and a phosphorus compound, and the shape thereof However, it is essential that the length of one side is 5 to 100 nm and the interlayer interval is 1 to 5 nm. Furthermore, the metal in the layered nanoparticle is a divalent metal, and it is further preferable that the layered nanoparticle is generated by externally adding a metal and a phosphorus compound during the production process. .

  As a more specific method for producing the polyester fiber of the present invention, the obtained polyester polymer can be melted at a temperature of 285 to 335 ° C., and a spinneret equipped with a capillary can be used for spinning. Moreover, it is preferable to pass through a heated spinning cylinder having a temperature equal to or higher than the molten polymer temperature immediately after discharging from the spinneret. The length of the heated spinning cylinder is preferably 10 to 500 mm. Since the polymer immediately after being discharged from the spinneret tends to be easily oriented, and single yarn breakage is likely to occur, it is preferable to use the heated spinning cylinder for delayed cooling in this way.

  The spun yarn that has passed through the heated spinning cylinder is preferably cooled by blowing cold air of 30 ° C. or lower. Furthermore, it is preferable that it is a cold wind of 25 degrees C or less. Next, it is preferable to apply an oil agent to the cooled thread form.

  When the molten polymer composition is discharged from the spinneret and molded in this manner, the spinning speed is preferably 300 to 6000 m / min. Furthermore, as a forming method in the production method of the present invention, a method of further stretching after spinning is preferable from the viewpoint of high-efficiency production.

  In particular, the polyester fiber of the present invention is preferably spun at a high speed, and the spinning speed is preferably 1500 to 5500 m / min. In this case, the fiber obtained before drawing becomes a partially oriented yarn. When spinning at such a high speed and the fibers are highly oriented and crystallized, conventionally, the yarn is often cut at the spinning stage. However, in the present invention, it is presumed that the orientation crystallization progressed uniformly and the spinning defects could be reduced due to the effect of forming the layered nanoparticles dispersed in the polymer. As a result, it has been found that the spinning performance is greatly improved.

  The stretching condition is preferably 1.5 to 10 times after spinning. Thus, it is possible to obtain a drawn fiber with higher strength by drawing after spinning. Conventionally, even when spinning at a low magnification, there is often a portion where the strength is weak due to the defect of the crystal at the time of drawing. However, in the present invention, due to the presence of the layered nanocompound, fine crystals are uniformly formed in crystallization by stretching, and stretching defects are less likely to occur. As a result, the fiber can be stretched at a high magnification, and the fiber can be increased in strength.

  As a stretching method for obtaining the polyester fiber of the present invention, the polyester fiber may be temporarily wound from a take-up roller and then stretched by a so-called separate stretching method. Or you may extend | stretch by what is called a direct extending | stretching method which supplies an undrawn thread | yarn continuously to a extending process from a take-off roller. The stretching conditions are one-stage or multi-stage stretching, and the stretching load factor is preferably 60 to 95%. The drawing load factor is the ratio of the tension at the time of drawing to the tension at which the fiber actually breaks.

  The preheating temperature at the time of drawing is preferably carried out at a temperature not lower than 20 ° C. below the glass transition point of the polyester undrawn yarn and not higher than 20 ° C. below the crystallization start temperature. Although the draw ratio depends on the spinning speed, it is preferable to draw at a draw ratio at which the draw ratio is 60 to 95% with respect to the breaking draw ratio. In order to maintain the strength of the fiber and improve the dimensional stability, it is preferable to perform heat setting at a temperature from 170 ° C. to the melting point of the fiber or less in the drawing step. Furthermore, it is preferable that the heat setting temperature at the time of Enjin is in the range of 170 to 270 ° C.

  In such a production method of the present invention, the crystallinity of the polymer composition is improved by the polyester polymer containing layered nanoparticles unique to the present invention. At the stage of melting and discharging from the spinneret, a large number of microcrystals are formed. The microcrystals suppress coarse crystal growth that occurs in the spinning and drawing processes and finely disperse the crystals. It is considered that the fine dispersion of crystals significantly reduced the yarn breaking rate in each step, and the physical properties of the finally obtained polyester fiber were improved.

  At this time, as a method for producing the polyester fiber of the present invention, the layered nanoparticles in the polyester used in the production method of the present invention are produced by externally adding a metal element and a phosphorus compound during the polyester production process. It is preferable. Thus, when the layered nanoparticles are precipitated internally, the fine dispersion of the layered nanoparticles can be further promoted compared to the case where the layered nanoparticles are added from the outside, and the performance of the resulting fiber is improved. It is also one of preferred embodiments that a polyester master polymer containing such layered nanoparticles in high concentration is prepared in advance and diluted with a polyester base polymer.

  Various devices have been conventionally used for high-speed spinning of polyester fibers. However, in the present invention, by including layered nanoparticles unique to the present invention, spinning stability has been dramatically improved, and high-speed spinning has also been achieved. It has become possible. Furthermore, since yarn breakage hardly occurs, a practical draw ratio can be increased, and a polyester fiber having higher strength can be obtained.

  The polyester fiber of the present invention has little decrease in the intrinsic viscosity IVf of the fiber and has a very high breaking spinning speed. In addition, there is little variation in high strength, low unloading (high modulus), and high elongation, and even with low dry yield, there are few fuzz defects and good yarn production.

  The mechanism that exerts the effect of the present invention is not necessarily clear, but contains fine layered nanoparticles, and the dispersion of the fine particles reinforces the polyester polymer or suppresses concentration of stress on the defects, This is probably because the structural defects of the fibers have been reduced. In the polyester fiber of the present invention, the layered nanoparticles are preferably specifically oriented parallel to the fiber axis. Thereby, the polymer molecules are regularly oriented, and it is considered that the effects such as improvement of breaking spinning speed, reduction of fuzz defects, improvement of yarn-making property, and reduction of variation in physical properties are exhibited.

  The strength of the polyester fiber of the present invention obtained by the above production method is preferably 4.0 to 10.0 cN / dtex. Furthermore, it is preferably 5.0 to 9.5 cN / dtex. When the strength is too low, the durability tends to be inferior when the strength is too high. In addition, if production is performed with a very high strength, yarn breakage tends to occur in the yarn making process, and there is a problem in quality stability as an industrial fiber.

  The dry heat shrinkage at 180 ° C. is preferably 1 to 15%. When the dry heat shrinkage rate is too high, the dimensional change during processing tends to increase, and the dimensional stability of a molded product using fibers tends to be poor.

  Although there is no limitation in particular in the single yarn fineness of the polyester fiber obtained, it is preferable that it is 0.1-100 dtex / filament from a viewpoint of yarn-making property. Particularly, rubber reinforcing fibers such as tire cords and V-belts, and industrial material fibers are preferably 1 to 20 dtex / filament from the viewpoint of strength, heat resistance and adhesiveness.

  The total fineness is not particularly limited, but is preferably 10 to 10,000 dtex. Particularly, rubber reinforcing fibers such as tire cords and V-belts, and industrial material fibers are preferably 250 to 6,000 dtex. In addition, as the total fineness, for example, 2 to 10 yarns may be spun during spinning or drawing, or after the end of each, so that two fibers of 1,000 dtex are combined to a total fineness of 2,000 dtex. preferable.

  Furthermore, it is also preferable that the polyester fiber of the present invention is a cord in which the above-described polyester fiber is multifilament and twisted. By twisting the multifilament fiber, the strength utilization rate is averaged and the fatigue property is improved. The number of twists is preferably in the range of 50 to 1000 times / m. At this time, it is also preferable that the cord is a yarn obtained by twisting and twisting. The number of filaments constituting the yarn before being combined is preferably 50 to 3000. By using such a multifilament, fatigue resistance and flexibility are further improved. When the fineness is too small, the strength tends to be insufficient. On the other hand, if the fineness is too large, it becomes too thick and flexibility cannot be obtained, and sticking between single yarns tends to occur during spinning, and it tends to be difficult to produce stable fibers.

  In the method for producing a polyester fiber of the present invention, a desired fiber cord can be obtained by further twisting or combining the obtained fibers. Furthermore, it is also preferable to apply an adhesive treatment agent to the surface. As an adhesion treatment agent, treating an RFL adhesion treatment agent is optimal for rubber reinforcement applications.

  More specifically, such a fiber cord can be obtained by adding a twisted yarn according to a conventional method to the above-mentioned polyester fiber, or attaching an RFL treatment agent in a non-twisted state and performing a heat treatment. Such a fiber becomes a treatment cord which can be suitably used for rubber reinforcement. In particular, the composite comprising the polyester fiber of the present invention and the polymer is excellent in moldability when formed into a composite because the polyester fiber of the present invention used for reinforcement is excellent in heat resistance and dimensional stability. It will be. In particular, it is optimal for rubber reinforcement and can be suitably used for tires, V belts, conveyor belts, and the like.

  The present invention will be further described in the following examples, but the scope of the present invention is not limited by these examples. Various characteristics were measured by the following methods.

(1) Intrinsic viscosity:
The diluted solution which melt | dissolved the polyester chip | tip and the polyester fiber in orthochlorophenol for 60 minutes at 100 degreeC was calculated | required from the value measured using the Ubbelohde viscometer at 35 degreeC.
Indicated as IV.

(2) Diethylene glycol content:
The polyester composition chip was decomposed using hydrazine hydrate (hydrated hydrazine), and the content of diethylene glycol in the decomposed product was measured using gas chromatography (manufactured by Hewlett-Packard (HP 6850 type)).

(3) Content measurement of phosphorus and each metal atom Content of each metal element was extracted with 0.5 N hydrochloric acid after the sample was dissolved in orthochlorophenol. Basically, the extract was quantified using a Hitachi Z-8100 atomic absorption spectrophotometer.
In addition, the content of each element such as phosphorus and antimony, manganese, cobalt, and zinc, which are not suitable for atomic absorption, was measured using a fluorescent X-ray apparatus (Rigaku Corporation 3270E type) and subjected to quantitative analysis. In the case of this fluorescent X-ray measurement, for the chip / fibrous polyester resin polymer, a test molding having a flat surface under a pressure condition of 7 MPa while heating the sample at 260 ° C. for 2 minutes with a compression press machine. A body was created and measurements were taken.

(4) X-ray diffraction For the X-ray diffraction measurement of the polyester composition / fiber, an X-ray diffraction apparatus (RINT-TTR3, Cu-Kα ray, tube voltage: 50 kV, current 300 mA, parallel beam method, manufactured by Rigaku Corporation) is used. Used. The interlayer distance d (angstrom) of the layered nanoparticles was calculated from a diffraction peak appearing in the equator direction of 2θ (theta) = 2 to 7 ° using a 2θ (theta) -d conversion table.

(5) Analysis of layered nanoparticles Presence / absence of layered nanoparticles and confirmation of constituent elements were carried out by preparing ultrathin sections of polyester resin / fiber with a thickness of 50-100 nm by a conventional method, and using a transmission electron microscope (manufactured by FEI). TECNAI G2) Observation was carried out at an acceleration voltage of 120 kV, and elemental analysis was carried out at a transmission electron microscope (JEM-2010, manufactured by JEOL Ltd.) with an acceleration voltage of 100 kV and a probe diameter of 10 nm. The length of one piece of particles was determined from the obtained image.

(6) Fiber strength, elongation and intermediate unloading (loading)
It measured according to JIS L-1013 using the tensile load measuring device (Shimadzu Corporation autograph). Intermediate unloading represented elongation at a strength of 4 cN / dtex. An average value obtained by measuring 50 points was obtained, and a standard deviation σ (sigma) representing variation in each physical property was calculated.

(7) Dry heat shrinkage of fiber (dry yield)
According to JIS-L1013, it was left for 24 hours in a temperature and humidity controlled room at 20 ° C. and 65% RH. Thereafter, heat treatment was performed at 180 ° C. for 30 minutes in a dryer in a no-load state, and calculation was performed based on the difference in test length before and after the heat treatment.

(8) Fluff defect of product The following evaluation was made according to the fluff defect caused by single yarn breakage in the appearance inspection of the wound fiber product.
◎: Very good with no fuzz defects ○: Slight occurrence of fuzz defects is observed, but good △: Some fluff is generated and product loss is slightly high ×: Product loss is very high due to frequent occurrence of fuzz

(9) Threading property Evaluation was made below according to the number of yarn breaks per ton of the wound fiber product.
◎: 0 or more and less than 0.5 times / ton ○: 0.5 or more and less than 1.0 times / ton △: 1.0 or more and less than 3.0 times / ton ×: 3.0 times or more / ton

[Example 1]
Manufacture of a polyester composition chip Manganese acetate tetrahydrate 0.0735 parts by mass (compared to DMT 30 mmol%) in a mixture of 194.2 parts by weight of dimethyl terephthalate and 124.2 parts by mass of ethylene glycol (200 mol% compared to DMT) ) Was charged into a reactor equipped with a stirrer, rectification column and methanol distillation condenser. Subsequently, the ester exchange reaction was carried out while gradually raising the temperature from 140 ° C. to 240 ° C. while distilling methanol produced as a result of the reaction out of the reactor. Thereafter, 0.0522 parts by mass of phenylphosphonic acid (33 mmol% relative to DMT) was added to complete the transesterification reaction. Thereafter, 0.0964 parts by mass of antimony trioxide (33 mmol% relative to DMT) was added to the reaction product, and the mixture was transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet, a vacuum port and a distillation apparatus. Subsequently, the temperature was raised to 290 ° C., and a polycondensation reaction was performed at a high vacuum of 30 Pa or less to obtain a polyester composition. Furthermore, it was made into a chip according to a conventional method.
When the obtained polyester chip was observed with a transmission electron microscope, it contained layered nanoparticles having a length of 20 nm and an interlayer distance of 1.5 nm. The results are shown in Table 1.

-Manufacture of polyester fiber The obtained polyester chip was dried and pre-crystallized in a nitrogen atmosphere at 160 ° C for 3 hours. Further, a solid state polymerization reaction was performed at 230 ° C. under vacuum. The intrinsic viscosity of the obtained polyethylene terephthalate composition chip was 1.02.
This was spun from a spinneret having a diameter of 1.0 mm and 250 holes at a polymer melting temperature of 296 ° C. The spun yarn was passed through a cylindrical heating zone heated to 300 ° C. with a length of 200 mm provided immediately below the base. Next, cooling air adjusted to 20 ° C. and 65% RH was blown onto the spun yarn from a cylindrical chimney with a blowing distance of 500 mm, and cooled. Furthermore, the oil agent which has an aliphatic ester compound as a main component was provided with an oil agent so that the amount of the oil agent adhered to the fiber was 0.5%. Then, it picked up with the speed | rate of 2500 m / min with the roller whose surface temperature is 50 degreeC.

Further, in order to measure the breaking spinning speed of the yarn, the take-up roller speed was gradually increased to determine the speed at which the spun yarn breaks.
The discharged yarn spun at a speed of 2500 m / min was continuously wound without first winding, and then the first stage drawing was performed 1.4 times with the first roller having a surface temperature of 60 ° C. Next, the second stage stretching of 1.15 times is performed between the first roller and the second roller having a surface temperature of 75 ° C., and the third stage being 1.4 times between the third roller having a surface temperature of 190 ° C. Stretching was performed. At this time, the running yarn was wound on the third roller and heat set at 190 ° C. for 0.2 seconds. Finally, after having taken up to the cooling roller by fixed length, it wound up with the winding speed of 5000 m / min, and obtained the polyester fiber.

  When the obtained polyester fiber was observed with a transmission electron microscope, it contained an average of 11 layered nanoparticles having a length of 20 nm and an interlayer distance of 1.5 nm. General particulate metal-containing particles were not observed. Further, it was observed from transmission microscope observation and X-ray diffraction that the layered nanoparticles were oriented parallel to the fiber axis. The obtained fiber had a small decrease in intrinsic viscosity IVf, and the breaking spinning speed was very high. Further, the strength, low unloading (high modulus), and strong elongation were small. Furthermore, despite the low dry yield, there were few fuzz defects and the yarn production was good. Table 2 shows the physical properties and process passability of the fibers.

[Examples 2 to 8]
In Example 1, it implemented like Example 1 except having changed into the compound kind and quantity shown in Table 1 instead of manganese acetate tetrahydrate and phenylphosphonic acid, and obtained the polyester polymer. The results are also shown in Table 1.
Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The obtained fiber contained layered nanoparticles, and general particulate metal-containing particles were not observed. Further, the obtained fiber had little decrease in intrinsic viscosity IVf, and the breaking spinning speed was very high. Further, the strength, low unloading (high modulus), and strong elongation were small. Furthermore, despite the low dry yield, there were few fuzz defects and the yarn production was good. In particular, when phenylphosphonic acid was used, the effect was well exhibited even with a small content. The results are also shown in Table 2.

[Example 9]
A slurry composed of 166.13 parts by mass of terephthalic acid and 74.4 parts of ethylene glycol was supplied to a polycondensation tank, and an esterification reaction was carried out at 250 ° C. under normal pressure. Bis (β-hydroxy having an esterification reaction rate of 95% Ethyl) terephthalate and its low polymer were prepared. Thereafter, 0.0735 parts by mass of manganese acetate tetrahydrate (30 mmol% relative to TA) was added and stirred for 5 minutes, and then 0.0522 parts by mass of phenylphosphonic acid (33 mmol% relative to TA) and 0.0964 of antimony trioxide. A part by mass (33 mmol% relative to TA) was added, and the mixture was transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet, a vacuum port and a distillation apparatus. The temperature of the reaction vessel was raised to 290 ° C., and a polycondensation reaction was performed under a high vacuum of 30 Pa or less to obtain a polyester composition. Furthermore, it was made into a chip according to a conventional method. The results are also shown in Table 1.

  Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The obtained fiber contained layered nanoparticles, and general particulate metal-containing particles were not observed. Further, the obtained fiber had little decrease in intrinsic viscosity IVf, and the breaking spinning speed was very high. Also, the variation in high strength, low unloading (high modulus) and strong elongation was small. Furthermore, despite the low dry yield, there were few fuzz defects and the yarn production was good. The results are also shown in Table 2.

[Comparative Examples 1-8]
In Example 1, it implemented like Example 1 except having changed into the compound kind and quantity shown in Table 1 instead of manganese acetate tetrahydrate and phenylphosphonic acid, and obtained the polyester polymer. When observed with an electron microscope, no layered nanoparticles were observed, and even in the presence of particles, the particles were in a general spherical form. The results are also shown in Table 1.
Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The results are also shown in Table 2.

[Comparative Example 9]
A polyester polymer was obtained in the same manner as in Example 9 except that manganese acetate tetrahydrate and phenylphosphonic acid were not added. When observed with an electron microscope, layered nanoparticles were not observed. The results are also shown in Table 1.
Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The results are also shown in Table 2.

[Comparative Example 10]
In Example 9, it implemented like Example 9 except having changed into the compound kind and quantity which are shown in Table 1 instead of manganese acetate tetrahydrate and phenylphosphonic acid, and obtained the polyester polymer. When observed with an electron microscope, layered nanoparticles were not observed. The results are also shown in Table 1.
Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The results are also shown in Table 2.

[Comparative Example 11]
To a mixture of 194.2 parts by mass of dimethyl terephthalate and 124.2 parts by mass of ethylene glycol (200 mol% relative to DMT), 0.0735 parts by mass of manganese acetate tetrahydrate (30 mmol% relative to DMT) was stirred and rectified. A reactor equipped with a column and a methanol distillation condenser was charged. Subsequently, the ester exchange reaction was carried out while gradually raising the temperature from 140 ° C. to 240 ° C. while distilling methanol produced as a result of the reaction out of the reactor. Thereafter, 0.0304 parts by mass of orthophosphoric acid (31 mmol% relative to DMT) was added to complete the transesterification reaction. Thereafter, an ethylene glycol solution of a layered silicate (Montmorillonite: Kunimine F Co., Ltd. Kunipia F) is added to the reaction product so that the content of the layered silicate is 1 part by mass with respect to the polyester composition, and then Then, 0.0964 parts by mass of antimony trioxide (33 mmol% relative to DMT) was added, and the mixture was transferred to a reaction vessel equipped with a stirrer, a nitrogen inlet, a vacuum port, and a distillation apparatus. Subsequently, the temperature was raised to 290 ° C., and a polycondensation reaction was performed at a high vacuum of 30 Pa or less to obtain a polyester composition. Furthermore, it was made into a chip according to a conventional method.
When the obtained polyester chip was observed with a transmission electron microscope, it contained layered particles (layered silicate) having a length of 150 nm and an interlayer distance of 1.3 nm, but one side had a length of 1 μm. Agglomerates of the above montmorillonite were observed. The results are shown in Table 1.
Furthermore, melt spinning and stretching were performed in the same manner as in Example 1 to obtain a polyester fiber. The results are also shown in Table 2.

The polyester fiber of the present invention thus obtained is a polyester fiber which is a high-quality and highly efficient polyester fiber with few defects such as voids due to catalyst particles and the like, and less physical property variation and fluff generation. Is very useful for a wide range of industrial material applications such as woven and knitted fabrics for industrial materials such as seat belts, tarpaulins, fish nets, ropes and monofilaments.
Further, it is also preferable to use a fiber / polymer composite in combination with a polymer. In particular, it is suitably used as a rubber reinforcing fiber whose polymer is a rubber elastic body, and is optimal for tires, belts, hoses, and the like.

Claims (11)

A fiber made of polyester, comprising metal-phosphorous layered nanoparticles made of a divalent metal and a phosphorus compound, having a side length of 5 to 100 nm and an interlayer spacing of 1 to 5 nm. Polyester fiber. Polyester fibers of at least one metal element is claimed in claim 1 wherein said divalent metal is selected from the group of 4 to 5 cycles and Groups 3 to 12 metal elements and Mg in the periodic table. The polyester fiber according to claim 1 or 2, wherein the divalent metal is at least one metal selected from the group consisting of Zn, Mn, Co, and Mg. The polyester fiber according to any one of claims 1 to 3 , wherein the metal-phosphorus compound constituting the layered nanoparticles is derived from a phosphorus compound represented by the following general formula (I).
(In the above formula, Ar represents an unsubstituted or substituted aryl group having 6 to 20 carbon atoms, R ¹ represents a hydrogen atom or OH group, R ² represents a hydrogen atom, or unsubstituted or substituted. Represents a hydrocarbon group having 1 to 20 carbon atoms.) The polyester fiber according to any one of claims 1 to 4 , wherein the metal-phosphorus compound constituting the layered nanoparticles is a phenylphosphonic acid derivative. The polyester fiber according to any one of claims 1 to 5 , wherein the metal and phosphorus contents in the polyester satisfy the following formula (III) and formula (IV).
10 ≦ M ≦ 1000 (III)
0.8 ≦ P / M ≦ 2.0 (IV)
(In the formula, M represents mmol% of the metal element with respect to the dicarboxylic acid component constituting the polyester, and P represents mmol% of the phosphorus element.) The main repeating unit of the polyester is selected from the group consisting of ethylene terephthalate, ethylene-2,6-naphthalate, trimethylene terephthalate, trimethylene-2,6-naphthalate, butylene terephthalate, butylene-2,6-naphthalate. Item 7. The polyester fiber according to any one of Items 1 to 6 . The polyester fiber according to any one of claims 1 to 7 , wherein the polyester is polyethylene terephthalate. The polyester fiber according to any one of claims 1 to 8 , which has a diffraction peak at 2θ (theta) = 5 to 7 ° in XRD diffraction in the equator direction of the fiber. A method for producing a polyester fiber in which a polyester containing layered nanoparticles is melt-spun, wherein the layered nanoparticles are composed of a divalent metal and a phosphorus compound, and the shape has a side length of 5 to 100 nm and an interlayer spacing is The manufacturing method of the polyester fiber characterized by being 1-5 nm. The method for producing a polyester fiber according to claim 10 , wherein the layered nanoparticles are precipitated internally by adding a divalent metal and a phosphorus compound during the production process.