JP2007126760A - Core-sheath conjugate fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remarkably improves drawbacks of a fiber composed of a thermotropic liquid crystal polyester that tends to fibrillate by friction and has low fatigue resistance to obtain a fiber having excellent operability. <P>SOLUTION: The core-sheath conjugate fiber comprises a core component composed of a thermotropic liquid crystal polyester (A) and a flexible thermoplastic polymer (B) and a sheath component composed of a thermotropic liquid crystal polyester (C) and a flexible thermoplastic polymer (D). The relationship between the conjugate ratio Rc(%) of the thermotropic liquid crystal polyester of the core component and the conjugate ratio Rs(%) of the thermotropic liquid crystal polyester of the sheath component satisfies Rc>Rs and Rc>50. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composite fiber having high strength and high elastic modulus and excellent in wear resistance and fatigue resistance. The composite fiber obtained by the present invention is used for general industrial materials, particularly ropes and rubbers. Reinforcement, geotextiles, FRP applications, computer ribbons, printed circuit board fabrics, air bags, bag filters, fishery materials such as fishing nets, screen rods, etc. are widely used.

  It is known that molten liquid crystal forming polyester fibers have high strength and high elastic modulus because molecular chains are highly oriented in the fiber axis direction. However, since a weak intermolecular force acts only in the direction perpendicular to the fiber axis, fibrils are easily generated by friction, causing a problem such as a decrease in fiber strength leading to breakage. Further, since kink bands due to buckling tend to occur and tend to localize, the fatigue resistance is poor.

Therefore, for the purpose of improving these drawbacks, a core-sheath type composite fiber in which the core component is a melt liquid crystal forming polyester and the sheath component is polyphenylene sulfide has been proposed (see Patent Document 1). In addition, as a composite fiber that suppresses peeling and fibrillation at the core-sheath component interface and has improved wear resistance and fatigue resistance, the core component is a melted liquid crystal forming polyester, the sheath component is a melted liquid crystal forming polyester, and flexibility A core-sheath type composite fiber made of a polymer alloy of a thermoplastic polymer has been proposed (see Patent Document 2). Furthermore, as a composite fiber with improved core resistance and wear resistance by eliminating the core-sheath interface, the entire fiber composed of molten liquid crystal forming polyester with island component and flexible thermoplastic polymer with sea component is made of polymer alloy. A composite fiber (see Patent Document 3) having a sea-island structure has been proposed.
Japanese Patent Laid-Open No. 1-229815 (FIG. 2) JP-A-8-260249 (FIG. 2) Japanese Patent Laid-Open No. 2003-239137 (FIG. 1)

  As described above, it is a fact that the fibrillation is suppressed and the wear resistance is improved by coating the periphery of the molten liquid crystal forming polyester as a composite fiber with a polymer that is difficult to fibrillate. However, since the drawing is performed at a spinning speed matched to the melted liquid crystal forming polyester, and the melted liquid crystal forming polyester does not require stretching, the flexible thermoplastic polymer to be combined remains in an unstretched state. For this reason, when the liquid crystal-forming polyester is solid-phase polymerized for higher strength, the flexible thermoplastic polymer becomes thermally crystallized and becomes brittle, and the core-sheath interface and the polymer alloy component interface during various processing and use of the fiber. Problems such as peeling off frequently occurred. Thus, the present invention has been found as a result of intensive investigations on improvement of wear resistance and fatigue resistance by suppressing peeling and fibrillation at the core-sheath interface and the polymer alloy component interface.

  In the present invention, the core component comprises a melt liquid crystal forming polyester (A) and a flexible thermoplastic polymer (B), and the sheath component comprises a melt liquid crystal forming polyester (C) and a flexible thermoplastic polymer (D). The relationship between the composite ratio Rc (%) of the molten liquid crystal forming polyester as the core component and the composite ratio Rs (%) of the molten liquid crystal forming polyester as the sheath component is Rc> Rs, Rc> 50. It is a core-sheath type composite fiber characterized by satisfying

  According to the present invention, it is possible to obtain a core-sheath-type composite fiber that has high strength and high elastic modulus, suppresses core-sheath interface peeling, and is excellent in wear resistance and fatigue resistance.

  In the core-sheath type composite fiber of the present invention, the molten liquid crystal forming polyester (A) used for the core component and the molten liquid crystal forming polyester (C) used for the sheath component are optically anisotropic when heated and melted. Refers to a polymer exhibiting This characteristic can be identified by, for example, heating a sample made of molten liquid crystal-forming polyesters (A) and (C) on a hot stage and heating in a nitrogen atmosphere, and observing the transmitted light of the sample under polarized light.

  Conventionally known methods can be used for the polymerization formulation of the melt liquid crystal forming polyesters (A) and (C) used in the present invention.

  Examples of the melt liquid crystal forming polyesters (A) and (C) used in the present invention include a. A polymer of aromatic oxycarboxylic acid, b. Polymer of aromatic dicarboxylic acid and aromatic diol, aliphatic diol, c. and a copolymer of a and b.

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

  Examples of the aromatic dicarboxylic acid 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 aromatic dicarboxylic acid. Examples include halogen substitution products.

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

  Preferable examples of the melt liquid crystal-forming polyesters (A) and (C) used in the present invention include a copolymer of a p-hydroxybenzoic acid component and an ethylene terephthalate component, a p-hydroxybenzoic acid component and 4,4. '-Dihydroxybiphenyl component and terephthalic acid component or isophthalic acid component copolymerized, p-hydroxybenzoic acid component and 6-hydroxy 2-naphthoic acid component copolymerized, p-hydroxybenzoic acid component And a copolymer of a 6-hydroxy 2-naphthoic acid component, a hydroquinone component, and a terephthalic acid component.

  The melting point of the melt liquid crystal forming polyesters (A) and (C) used in the present invention is preferably in the range of 220 to 380 ° C., more preferably so as not to cause processing problems in spinning, solid phase polymerization and the like. It is a thing of 250-350 degreeC.

  The present invention provides a core-sheath type having a high strength and a high elastic modulus and excellent in dimensional stability possessed by a molten liquid crystal forming polyester by using a polymer alloy containing a molten liquid crystal forming polyester as a core component and a sheath component. Bicomponent fibers can be provided.

  In the present invention, the molten liquid crystal forming polyester (A) used for the core component and the molten liquid crystal forming polyester (C) used for the sheath component may be the same or different in composition, viscosity, etc. Various changes can be made according to the dispersion state control of the sheath component and the characteristics required for various applications. The molten liquid crystal forming polyesters (A) and (C) may be a molten liquid crystal forming polyester alone or a polymer alloy composed of two or more molten liquid crystal forming polyesters.

  In the present invention, the flexible thermoplastic polymer (B) used for the core component and the flexible thermoplastic polymer (D) used for the sheath component may be the same or different in properties such as polymer type and viscosity, Various changes can be made according to the dispersion state control of the core component and the sheath component and the characteristics required for various applications. The flexible thermoplastic polymers (B) and (D) may be a flexible thermoplastic polymer alone or a polymer alloy composed of two or more flexible thermoplastic polymers.

  Examples of the flexible thermoplastic polymers (B) and (D) used in the present invention include polyesters, vinyl polymers such as polyolefin and polystyrene, polycarbonates, polyamides, polyimides, polyphenylene sulfides, polyphenylene oxides, polysulfones, and aromatic polyketones. , Aliphatic polyketone, semi-aromatic polyesteramide, polyester ether ketone, fluororesin and the like. Among these flexible thermoplastic polymers, polyphenylene sulfide is preferable from the viewpoint that properties such as solvent resistance can be imparted. From the viewpoint of adhesiveness, polyamides represented by nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T and the like are preferable. Furthermore, from the viewpoint of abrasion resistance, polyesters represented by polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexanedimethanol terephthalate, polyester 99M and the like are preferable.

  In the core-sheath type composite fiber of the present invention, the flexible thermoplastic polymer (B) used for the core component is preferably polyethylene naphthalate. Polyethylene naphthalate has a high affinity with molten liquid crystal forming polyester and a higher melting point than other general-purpose polyesters. Is stable, it is difficult for the dispersion state of the polymer alloy to change, and it is excellent in workability in various post-processing such as solid phase polymerization after spinning.

  Polyethylene naphthalate in the present invention is a dicarboxylic acid component in which 80 mol% or more, preferably 90 mol% or more is naphthalenedicarboxylic acid, and a glycol component in which 80 mol% or more, preferably 90 mol% or more is ethylene glycol. Polyethylene naphthalate.

  Here, examples of naphthalenedicarboxylic acid include 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid, and preferably 2,6-naphthalenedicarboxylic acid. is there.

  In the present invention, the flexible thermoplastic polymers (B) and (D) may contain other copolymer components in a proportion of 20 mol% or less, more preferably 10 mol% or less. For example, the compound copolymerizable with polyamide may include, but is not limited to, sodium acrylate, N-vinylpyrrolidone, acrylic acid, methacrylic acid, vinyl alcohol, and a crosslinked polyethylene oxide polymer. . In addition, the compounds copolymerizable with polyester include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, benzophenonedicarboxylic acid, and phenylindanedicarboxylic acid as acid components. , Oxalic acid, succinic acid, adipic acid, dimer acid, sebacic acid, cyclohexanedicarboxylic acid, decalindicarboxylic acid and other dicarboxylic acids, glycol component ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol, Examples thereof include, but are not limited to, polypropylene glycol.

  The molten liquid crystal forming polyesters (A) and (C) and the flexible thermoplastic polymers (B) and (D) used in the present invention may be various metal oxides, kaolin, Various additions such as inorganic substances such as silica, colorants, matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brighteners, end group blocking agents, compatibilizers, etc. A small amount of an agent may be contained.

  In the core-sheath type composite fiber of the present invention, the core component and the sheath are used in the case where different polymers are used for the molten liquid crystal forming polyesters (A) and (C) and the flexible thermoplastic polymers (B) and (D), respectively. From the viewpoints of dispersibility of the component polymer alloy, adhesion at the alloy interface of each component, and improvement in adhesion at the core-sheath interface between the core component and the sheath component, it is preferable to add a copolymer component or a compatibilizing agent.

  The core-sheath type composite fiber of the present invention has a core component composed of a melt liquid crystal forming polyester (A) and a flexible thermoplastic polymer (B), and a sheath component composed of a melt liquid crystal forming polyester (C) and a flexible thermoplastic polymer. (D) is a core-sheath type composite fiber, and by making the core component a polymer alloy, the interface between the molten liquid crystal-forming polyester and the flexible thermoplastic polymer increases in the vicinity of the boundary between the core component and the sheath component. Since the contact area between the core component and the sheath component is increased and the adhesion at the core-sheath interface is improved, peeling of the core-sheath interface can be suppressed.

  In addition, by making the sheath component a polymer alloy, the strength of the sheath component is improved, and the presence of molten liquid crystal forming polyester on the fiber surface forms fine irregularities on the fiber surface. The inter-fiber fusion can be suppressed.

  In the present invention, the relationship between the composite ratio Rc (%) of the melt liquid crystal forming polyester of the core component and the composite ratio Rs (%) of the melt liquid crystal forming polyester of the sheath component satisfies Rc> Rs, and Rc> 50, which allows more flexible thermoplastic polymers other than molten liquid crystal forming polyester to be present in the fiber surface layer than composite fibers composed of a single polymer alloy. Therefore, excellent wear resistance can be obtained, and high strength and high elastic modulus which are the characteristics of the melt liquid crystal forming polyester can be obtained.

  Here, regarding the composite ratio of the melt liquid crystal forming polyester, a photograph of a fiber cross section taken at a magnification of 5,000 to several tens of thousands times with a transmission electron microscope (TEM (H-800 type manufactured by Hitachi, Ltd.)). Using the image processing software (Winroof) manufactured by Mitani Corporation, after etching the component interface of the molten liquid crystal forming polyester shown in white in the TEM photograph, the total area of the molten liquid crystal forming polyester component per unit cross section It can be confirmed by seeking.

  In the core-sheath type composite fiber of the present invention, the composite ratio Rc (%) of the molten liquid crystal forming polyester in the core component is preferably in a range satisfying 50 <Rc <90. By setting the composite ratio Rc of the molten liquid crystal-forming polyester in the core component to less than 90%, the amount of the flexible thermoplastic polymer (B) present in the core-sheath interface portion increases, and thus the adhesive force at the core-sheath interface is improved. . In addition, by setting the composite ratio Rc of the molten liquid crystal forming polyester in the core component to more than 50%, the composite ratio of the molten liquid crystal forming polyester as a whole fiber can be increased. Strength and high elastic modulus can be obtained. The composite ratio Rc of the molten liquid crystal forming polyester in the core component is more preferably in the range of 55 to 85%, still more preferably in the range of 60 to 75%.

  The composite ratio Rs (%) of the melt liquid crystal forming polyester in the sheath component is preferably in a range satisfying 10 <Rs <50. By making the composite ratio Rs of the molten liquid crystal forming polyester in the sheath component more than 10%, the strength of the sheath component can be increased, and the molten liquid crystal forming polyester can be appropriately exposed on the fiber surface. Inter-fiber fusion in solid phase polymerization is suppressed. In addition, by setting the composite ratio Rs of the melt liquid crystal-forming polyester in the sheath component to less than 50%, a large amount of the flexible thermoplastic polymer (D) can be present on the fiber surface, so that the abrasion resistance of the fiber surface is improved. It becomes high and generation | occurrence | production of fluff etc. is suppressed. The composite ratio Rs of the melt liquid crystal forming polyester in the sheath component is more preferably in the range of 12.5 to 40%, and still more preferably in the range of 15 to 35%.

  As for the sheath component of the core-sheath-type composite fiber of the present invention, it is preferable that the melt liquid crystal-forming polyester (C) is an island component and the flexible thermoplastic polymer (D) is a sea component. Since the flexible thermoplastic polymer (D) is a sea component, the adhesion with the core component polymer alloy at the core-sheath interface is further improved, and there are many flexible thermoplastic polymers (D) on the fiber surface. Therefore, a fiber excellent in wear resistance can be obtained.

  In the core-sheath-type composite fiber of the present invention, the ratio of the sheath component to the entire fiber is sufficiently covered with the core component, and the effect of suppressing the core-sheath interface peeling by making both the core component and the sheath component a polymer alloy Can be obtained, and is preferably less than 0.2. The ratio of the sheath component referred to in the present invention refers to a photograph taken by Mitani Shoji Co., Ltd. with respect to a photograph obtained by photographing a fiber cross section at a magnification of 5,000 with a transmission electron microscope (TEM (H-800 type manufactured by Hitachi, Ltd.)). After etching the entire fiber cross section and the core-sheath component interface using image processing software (Winroof), it can be calculated by obtaining the area of the entire fiber cross section and the cross-sectional area of the core component.

  By making the ratio of the sheath component less than 0.2, the composite ratio of the molten liquid crystal forming polyester as a whole fiber can be increased. Therefore, the characteristics of the molten liquid crystal forming polyester are maintained while maintaining excellent wear resistance. High strength and high elastic modulus can be obtained.

  The core-sheath-type composite fiber of the present invention has a sea-island structure as a whole in the fiber cross section, and both the core component and the sheath component form a dispersed state in which the molten liquid crystal-forming polyester is an island component. Is preferred. By adopting such a structure, the interface between the molten liquid crystal-forming polyester and the flexible thermoplastic polymer in the vicinity of the boundary between the core component and the sheath component is increased, so that the adhesion at the core-sheath interface can be further improved. .

  In such a structure, for example, in one single fiber cross section, the fiber diameter obtained from the circumscribed circle of the fiber is (R), and in the same island component in the fiber, the island component When the diameter obtained from the circumscribed circle is (r), it is preferable that the island component of both the core component and the sheath component satisfies the ratio r / R ≦ 0.3 of the island component diameter to the fiber diameter. Here, in order to suppress the component interface peeling of the polymer alloy, the maximum island component preferably satisfies r / R ≦ 0.2. In order to obtain high strength and high elastic modulus, the minimum island component in the core component preferably satisfies r / R ≧ 0.001, more preferably satisfies r / R ≧ 0.005. It is. About one sheath component, the dispersion diameter of an island component is so preferable that it is fine.

  The core-sheath type composite fiber of the present invention has a high strength and a high elastic modulus which are the characteristics of the melt liquid crystal forming polyester, and the tensile strength of the fiber is preferably 10 cN / dtex or more, more preferably. 14 cN / dtex or more. In addition, in order to ensure sufficient dimensional stability and durability of the product in various applications, the elastic modulus is preferably 300 cN / dtex or more, more preferably 350 cN / dtex or more.

  Although an example about the manufacturing method of the core sheath type composite fiber of the present invention is shown below, the present invention is not limited at all by this.

  The core-sheath type composite fiber of the present invention can be produced by a known core-sheath composite base, and the cross-sectional shape of the obtained fiber may be any of a round cross section, a flat shape, a multileaf cross section, etc. The core component includes not only a substantially similar shape to the fiber cross section, but also a complex form having a modified cross section and a multi-core structure.

  Regarding the core component of the core-sheath type composite fiber of the present invention and the polymer alloy of the sheath component, both the core component and the sheath component are once kneaded with a kneader and then spun and then directly melted with a kneader. Spinning can be carried out in one step using a spinning device, and the core component can be used in a spinning chip blend, and the sheath component can be used in advance by using a kneaded chip kneaded in advance. Examples of the kneader include a uniaxial kneader, a biaxial kneader, and various kneaders, and a biaxial kneader is preferable from the viewpoint of kneadability.

  The core-sheath type composite fiber of the present invention already has sufficient strength and elastic modulus just by spinning, but the performance can be further improved by solid phase polymerization.

The solid phase polymerization can be performed in an inert gas atmosphere such as nitrogen, an active gas atmosphere containing oxygen such as air, or under reduced pressure. The atmosphere of solid phase polymerization is preferably a low-humidity gas having a dew point of −40 ° C. or lower. The solid-state polymerization conditions are based on a component having a lower melting point of the sheath component polymers (C) and (D) as a reference and a temperature not exceeding the melting point of the reference component from a temperature lower by about 40 ° C than the melting point of the reference component. It is preferable to carry out solid phase polymerization. At this time, in order to prevent inter-fiber fusion, the solid phase polymerization temperature is preferably about 5 ° C. lower than the melting point of the reference component. The starting temperature of the solid phase polymerization can be any temperature as long as it is not higher than the temperature at which the solid phase polymerization is performed. Furthermore, the solid phase polymerization time is several minutes to several tens of hours depending on the target performance. For the solid phase polymerization, it is preferable to raise the temperature stepwise in order to prevent fusion between fibers due to rapid temperature rise. A stage for proceeding crystallization may be provided, for example, by performing treatment for several minutes to several hours at a temperature not exceeding the crystallization temperature of the polymer (D).

Here, the crystallization temperature is measured under a temperature increase condition of 16 ° C./min from room temperature in a differential calorimetry performed by a differential scanning calorimeter (DSC) manufactured by PerkinElmer Co., Ltd. using a spinning yarn as a sample. It refers to the exothermic peak temperature (Tc ₁ ) observed at the time.

  In the solid phase polymerization, various additives may be added to promote the solid phase polymerization of the melt liquid crystal forming polyesters (A) and (C).

Heat supply during solid-phase polymerization uses a method using a medium such as liquid and gas, a method using radiation by a heating plate, an infrared heater, etc., a method performed by contacting a heat roller, a heat plate, etc., a high frequency, etc. Can be used. In addition, solid phase polymerization is performed under tension or no tension depending on the purpose, and the solid phase polymerization is performed in a drum shape, a cake shape, a tow shape (for example, on a metal net), or continuously between rollers. It can also be processed as a yarn, and can also be subjected to solid phase polymerization after forming a fiber molded body such as a fabric or woven or knitted fabric.
The core-sheath type composite fiber of the present invention has excellent wear resistance only by performing solid phase polymerization. However, in order to further improve the wear resistance, the polymer (D It is preferable to perform high-temperature short-time heat treatment at a temperature of melting point of 20) + 20 ° C. or more and a time of 0.001 seconds to 5 seconds. By setting the melting point of the polymer (D) to 20 ° C. or higher, the effect of heat treatment is likely to occur in a short time, so that the heat treatment can be performed efficiently, for example, with little influence on the strength of the molten liquid crystal forming polyester. The heat treatment temperature may be within a general heater temperature control range, preferably in the range of melting point + 20 ° C. to melting point + 500 ° C., more preferably in the range of melting point + 30 ° C. to melting point + 300 ° C.
The heat treatment time is preferably 0.001 second or more and 5 seconds or less. The fiber can be prevented from fusing while maintaining an efficient heat treatment within this time range. The heat treatment time is preferably 0.005 seconds to 2 seconds, more preferably 0.01 seconds to 1 second.
Furthermore, non-contact heat treatment is preferable in order to prevent wear due to contact with a guide or the like during the heat treatment step and to perform uniform heat treatment. Moreover, as a preferable heat source, a slit heater using a general plate heater, laser heating, or the like can be used.

  By performing a high-temperature and short-time heat treatment, a fiber having a characteristic that the crystallization temperature can be confirmed by differential scanning calorimetry (DSC) measurement even for a yarn after solid-phase polymerization. In this case, heat treatment is preferably performed so that the crystallization heat amount ΔHc is 3 J / g or more.

  The form of the core-sheath type composite fiber of the present invention can be either a filament form or a cut fiber form.

  The core-sheath type composite fiber of the present invention retains the characteristics of high strength and high elastic modulus, and has remarkably improved fibrillation resistance, wear resistance, and fatigue resistance. Widely used in the fields of building materials, sports applications, protective clothing, rubber reinforcement materials, electrical materials (especially as tension members), acoustic materials, and general clothing. Effective applications include screen kites, computer ribbons, printed circuit board fabrics, paper canvases, airbags, airships, dome fabrics, rider suits, fishing lines, various lines (yachts, paragliders, balloons, kites) Thread), blind cords, support cords for screen doors, various cords in automobiles and aircraft, power transmission cords for electrical products and robots, etc. Especially effective applications are textiles for industrial materials, especially from the point of wear resistance The screen can be cited.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this. The various characteristics of the present invention were evaluated by the following methods.
-Tensile strength and elongation, elastic modulus: Physical properties after solid-phase polymerization were measured using Tensilon UCT-100 manufactured by Orientec Corporation according to the method described in JIS L1013.
Melt viscosity: Measured using a Capillograph type 1B manufactured by Toyo Seiki Co., Ltd.
Melting point: Observation of the endothermic peak temperature (Tm ₁ ) observed when measured with a temperature increase condition of 16 ° C./min from room temperature in differential calorimetry performed by a differential scanning calorimeter (DSC) manufactured by PerkinElmer Co., Ltd. Then, after holding at a temperature of about Tm ₁ + 20 ° C. for 5 minutes, after rapidly cooling to room temperature (holding for 5 minutes by combining the rapid cooling time and room temperature holding time), when measuring again at 16 ° C./min. The observed endothermic peak temperature (Tm ₂ ) was taken as the melting point.
・ Abrasion resistance: As an evaluation sample, a monofilament obtained by solid-phase polymerization of a spinning raw yarn and then splitting as necessary, and contact angle with a φ3 mm ceramic rod guide installed on a horizontally moving pulley The end of the sample applied at 100 ° is held by a stroke device, a load of 5.0 cN / dtex is hung in the horizontal movement direction of the pulley, and the stroke device is operated at a stroke length of 30 mm and a speed of 100 times / min. The sample was rubbed to measure the number of strokes when the whitening of the yarn due to peeling of the core-sheath interface was confirmed.
・ Polymer alloy dispersion state and component confirmation, composite ratio of molten liquid crystal forming polyester, and ratio of sheath component to the whole fiber: 5,000 times to several times by transmission electron microscope (TEM (H-800 type manufactured by Hitachi, Ltd.)) For photographs of fiber cross-sections taken at a magnification of 10,000 times, for melted liquid crystal formation using image processing software (Winroof) manufactured by Mitani Corporation for photographs taken of fiber cross-sections at a magnification of 5,000 to tens of thousands of times It calculated and confirmed by performing various processes, such as a property polyester component and a core sheath component interface.

Example 1
As the melted liquid crystal forming polyesters (A) and (C), 72 mol% of the structural units generated from p-hydroxybenzoic acid and 28 mol% of the structural units generated from 6-hydroxy-2-naphthoic acid are used. Occupied molten liquid crystal forming polyester was used. The melt viscosity of this molten liquid crystal forming polyester was 115 Pa · s at a measurement temperature of 300 ° C., a shear rate of 100 sec ⁻¹ , and a melting point of 278 ° C. (hereinafter, this polymer is referred to as LCP1).

As the flexible thermoplastic polymers (B) and (D), polyethylene naphthalate obtained by polycondensation of 2,6-naphthalenedicarboxylic acid and ethylene glycol was used. The polyethylene naphthalate had a melt viscosity of 350 Pa · s at a measurement temperature of 300 ° C., a shear rate of 100 sec ⁻¹ , and a melting point of 268 ° C. (hereinafter, this polymer is referred to as PEN1).

  The core component is mixed in a pellet state so that the composite ratio of the polymer (A) is 60 wt%, and the sheath component is mixed so that the composite ratio of the polymer (C) is 15 wt%. Polymer alloy chips used for the core component and the sheath component were respectively prepared by melting and kneading with a ruder (screw diameter φ15 mm).

  The core component polymer and the sheath component polymer are melted by separate extruders and supplied to the spinning pack. The core sheath has a hole diameter of 0.13 mm, a hole depth of 0.26 mm, and 10 holes so that the ratio of the sheath component is 0.175. The composite die was discharged at a spinning temperature of 315 ° C. and wound at a spinning speed of 600 m / min to obtain a 100 dtex filament. At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  Regarding the dispersion state of the fiber cross section, both the core component and the sheath component are composed of a melt liquid crystal forming polyester and a sea component of polyethylene naphthalate, and the melt liquid crystal forming polyester is an island component and polyethylene as a whole fiber. Naphthalate formed a sea-island structure of sea components.

  As a result of performing image processing on the fiber cross section, the composite ratio of the molten liquid crystal forming polyester in the core component is 60%, and the composite ratio of the molten liquid crystal forming polyester in the sheath component is 15%. The ratio was 0.175.

  100 g of this spinning raw material is wound on a solid-state polymerization bobbin in which a heat-resistant nonwoven fabric is wound around a metal cylinder that allows gas to pass through, and nitrogen gas is supplied at 200 ° C. for 5 hours, 230 ° C. for 5 hours, and 260 ° C. for 20 hours. Solid state polymerization was conducted while passing through. When the obtained solid phase polymerized yarn was unwound, there was almost no interfiber fusion, the unwinding property was good, and the following performance was obtained.

Strength 11.6 cN / dtex
Elongation 3.1%
Elastic modulus 320 cN / dtex
Further, the evaluation result of the wear resistance was 160 times, and the core-sheath interface peeling hardly occurred, and the wear resistance was excellent.

Example 2
As a flexible thermoplastic polymer (B), polyethylene naphthalate having a melt viscosity of 135 Pa · s and a melting point of 268 ° C. under measurement conditions of a measurement temperature of 300 ° C. and a shear rate of 100 sec ⁻¹ (hereinafter, this polymer is referred to as PEN 2). ) Was used in the same manner as in Example 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the cross section of the fiber is that both the core component and the sheath component are composed of the melted liquid crystal forming polyester for the island component and polyethylene naphthalate for the sea component. Phthalate formed a sea-island structure with sea components. Further, the dispersion diameter of the molten liquid crystal forming polyester in the core component was larger than that in Example 1.

  As a result of performing image processing on the fiber cross section, the composite ratio of the molten liquid crystal forming polyester in the core component is 60%, and the composite ratio of the molten liquid crystal forming polyester in the sheath component is 15%. The ratio was 0.175.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the abrasion resistance evaluation value was 150 times.

  Various evaluation results are shown in Table 1.

Example 3
As the flexible thermoplastic polymer (B), polyethylene naphthalate obtained by copolymerizing 8 mol% of a terephthalic acid component was used. This polyethylene naphthalate had a melt viscosity of 225 Pa · s and a melting point of 254 ° C. under measurement conditions of a measurement temperature of 300 ° C. and a shear rate of 100 sec ⁻¹ (hereinafter, this polymer is referred to as PEN3).

As melted liquid crystal forming polyester (C), it was produced from structural unit (1) produced from p-acetoxybenzoic acid, structural unit (2) produced from 4,4-dihydroxybiphenyl and terephthalic acid, ethylene glycol and terephthalic acid. It consists of structural unit (3) of polyester, structural unit (1) accounts for 80 mol% of the total, and the total of structural unit (2) and structural unit (3) occupies 20 mol%, and structural unit (2) / (3 ) Was used as a molten liquid crystal forming polyester having a molar ratio of 3/5. The melt viscosity of this molten liquid crystal forming polyester was 48.6 Pa · s and the melting point was 315 ° C. under the measurement conditions of a measurement temperature of 320 ° C. and a shear rate of 100 sec ⁻¹ (hereinafter, this polymer is referred to as LCP2).

As the flexible thermoplastic polymer (D), linear polyphenylene sulfide having a polymer chain terminal at the COOH terminal was used. This polyphenylene sulfide had a melt viscosity of 51 Pa · s and a melting point of 280 ° C. under measurement conditions of a measurement temperature of 300 ° C. and a shear rate of 100 sec ⁻¹ (hereinafter, this polymer is referred to as PPS1).

  As described above, spinning was performed in the same manner as in Example 1 except that the polymer (C) and the polymer (D) were changed and discharged at a spinning temperature of 325 ° C.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the cross section of the fiber is that the island component is composed of a melt liquid crystal forming polyester for both the core component and the sheath component, the sea component is composed of polyethylene naphthalate for the core component, and polyphenylene sulfide for the sheath component. A sea-island structure in which the forming polyester is an island component was formed.

  As a result of performing image processing on the fiber cross section, the composite ratio of the molten liquid crystal forming polyester in the core component is 60%, and the composite ratio of the molten liquid crystal forming polyester in the sheath component is 15%. The ratio was 0.175.

  This spinning yarn was subjected to solid state polymerization in a nitrogen gas atmosphere at 250 ° C. for 3 hours, 260 ° C. for 3 hours, and 280 ° C. for 10 hours. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the evaluation value of wear resistance was 110 times.

  Various evaluation results are shown in Table 1.

Example 4
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (A) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  Regarding the dispersion state of the fiber cross section, the core component is polyethylene naphthalate as the island component, the sea component is the molten liquid crystal forming polyester, and is the reverse configuration of Example 1, and the sheath component is the molten liquid crystal forming polyester as the island component. The sea component was polyethylene naphthalate as in Example 1.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the evaluation value of abrasion resistance was 115 times.

  Various evaluation results are shown in Table 1.

Example 5
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (A) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  Regarding the dispersion state of the fiber cross section, the core component is polyethylene naphthalate as the island component, the sea component is the molten liquid crystal forming polyester, and is the reverse configuration of Example 1, and the sheath component is the molten liquid crystal forming polyester as the island component. The sea component was polyethylene naphthalate as in Example 1.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the abrasion resistance evaluation value was 85 times.

  Various evaluation results are shown in Table 1.

Example 6
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (A) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had low strength and elastic modulus, and the evaluation value of abrasion resistance was 150 times.

  Various evaluation results are shown in Table 1.

Example 7
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (C) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the evaluation value of abrasion resistance was 135 times.

  Various evaluation results are shown in Table 1.

Example 8
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (C) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the abrasion resistance evaluation value was 50 times.

  Various evaluation results are shown in Table 1.

Example 9
Spinning was performed in the same manner as in Example 1 except that the composite ratio of the polymer (C) was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid phase polymerized yarn showed interfiber fusion in some places, and the unwinding property was inferior to that of Example 1.

  This fiber had high strength and elastic modulus, and the abrasion resistance evaluation value was 70 times. As a result of observing the surface of the yarn with an optical microscope, a peeled portion of the sheath that was thought to have been formed by forcibly unwinding the fused portion between fibers was confirmed.

  Various evaluation results are shown in Table 1.

Example 10
Spinning was performed in the same manner as in Example 1 except that the ratio of the sheath component was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had high strength and elastic modulus, and the abrasion resistance evaluation value was 150 times.

  Various evaluation results are shown in Table 1.

Example 11
Spinning was performed in the same manner as in Example 1 except that the ratio of the sheath component was changed as shown in Table 1.

  At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  This fiber had low strength and elastic modulus, and the abrasion resistance evaluation value was 170 times.

  Various evaluation results are shown in Table 1.

Example 12
About the solid state polymerized yarn obtained by spinning and solid phase polymerization in the same manner as in Example 1, using a slit heater having a slit width of 2 mm, a slit depth of 5 mm, and a heat treatment length of 500 mm, a processing temperature of 310 ° C. and a yarn passing speed of 100 m Heat treatment was performed at / min.

  Although the strength and elastic modulus of this fiber were almost the same as those of Example 1, the abrasion resistance evaluation value was 380 times, which was significantly improved from that of Example 1.

  As a result of differential scanning calorimetry (DSC) measurement of this fiber, a crystallization peak was confirmed at 167 ° C., and the crystallization heat amount ΔHc was 4.7 J / g.

  Various evaluation results are shown in Table 1.

Comparative Example 1
The polymer alloy tip used for the core component of Example 1 was discharged at a spinning temperature of 315 ° C. using a single component die having a nozzle diameter of 0.13 mm, a nozzle length of 0.26 mm and 24 holes, and wound at a spinning speed of 600 m / min. As a result, a single component polymer alloy filament having the same fiber-to-fiber polymer alloy ratio of 240 dtex was obtained. At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.

  Regarding the dispersion state of the fiber cross section, the island component was composed of molten liquid crystal forming polyester and the sea component was composed of polyethylene naphthalate.

  As a result of performing image processing on the fiber cross section, the composite ratio of the melt liquid crystal forming polyester was 60%.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no inter-fiber fusion, good unwinding property, and had the following performance.

Strength 12.8 cN / dtex
Elongation 3.4%
Elastic modulus 315 cN / dtex
Further, the evaluation result of the wear resistance was 10 times, and fluff was likely to occur and the wear resistance was inferior.

Comparative Example 2
A polymer alloy chip prepared by mixing with a polymer (B) in a pellet state so that the composite ratio of the polymer (A) is 40 wt%, and melting and kneading with a biaxial extruder (screw diameter φ15 mm) is used as a core component. Spinning was performed in the same manner as in Example 1 except that the polymer alloy chip (composite ratio of molten liquid crystal forming polyester: 60 wt%) used in the core component in Example 1 was used as the sheath component.

At this time, there was no clogging of discharge holes, discharge bending, etc., and the yarn forming property was good.
The dispersion state of the fiber cross section was the same as in Example 1 for both the core component and the sheath component.

  As a result of performing image processing on the fiber cross section, the composite ratio of the molten liquid crystal forming polyester in the core component is 40%, the composite ratio of the molten liquid crystal forming polyester in the sheath component is 60%, and the sheath component occupies the entire fiber. The ratio was 0.175.

  This spinning yarn was subjected to solid phase polymerization in the same manner as in Example 1. The obtained solid state polymerized yarn had almost no interfiber fusion and had good unwinding property.

  Although this fiber had high strength and elastic modulus, the evaluation value of abrasion resistance was twice, and fluff was likely to occur and the abrasion resistance was poor.

  Various evaluation results are shown in Table 2.

Claims (5)

  A core-sheath type composite fiber in which the core component is composed of a molten liquid crystal forming polyester (A) and a flexible thermoplastic polymer (B), and the sheath component is composed of a molten liquid crystal forming polyester (C) and a flexible thermoplastic polymer (D). And the relationship between the composite ratio Rc (%) of the molten liquid crystal forming polyester as the core component and the composite ratio Rs (%) of the molten liquid crystal forming polyester as the sheath component satisfies Rc> Rs, Rc> 50 A core-sheath type composite fiber characterized by The composite ratio Rc (%) of the molten liquid crystal forming polyester in the core component and the composite ratio Rs (%) of the molten liquid crystal forming polyester in the sheath component satisfy the following formula. The core-sheath-type composite fiber according to claim 1, wherein (C) is an island component, and the flexible thermoplastic polymer (D) is a sea component.
50 <Rc <90, 10 <Rs <50   The core-sheath type composite fiber according to claim 1 or 2, wherein the ratio of the sheath component is less than 0.2.   The core-sheath type composite fiber according to any one of claims 1 to 3, wherein the flexible thermoplastic polymer (B) in the core component is polyethylene naphthalate.   The core sheath according to any one of claims 1 to 4, wherein the entire cross-section of the fiber forms a sea-island structure, and both the core component and the sheath component are made of molten liquid crystal forming polyester. Type composite fiber.