JP2000119952A - Liquid crystal polyester fiber and production of liquid crystal polyester nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce liquid crystal polyester fiber capable of providing nonwoven fabric having high porosity, small anisotropy in breaking length and excellent air permeability and flexibility by forming fiber made of a specific thermoplastic resin composition through melt spinning and then removing the thermoplastic resin through dissolving it in its solvent. SOLUTION: This liquid crystal polyester fiber is produced by extruding a thermoplastic resin composition comprising (A) 70.0-90.0 wt.% thermoplastic resin such as polycarbonate and poly(2,6-dimethylphenylene ether) and (B) 30.0-10.0 wt.% liquid crystal polyester such as a liquid crystal polyester including >=30 mol% repeating structural unit of the formula in a molten state from nozzles so as to form a continuous phase from the component A and a dispersed phase from the component B, by drawing filaments at >=3 times draft ratio, by cooling them to solidify and then dissolving the component A in a solvent such as chloroform to be removed. The above composition is pref. melted at a temperature higher than the flow-initiating temperature of the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to heat resistance, chemical resistance,
The present invention relates to a method for producing a nonwoven fabric having excellent air permeability, a liquid crystal polyester fiber having many entanglements, and a method for producing the same.

[0002]

2. Description of the Related Art Liquid crystal polyester has mechanical strength, heat resistance,
Because of its excellent chemical resistance, the resulting nonwoven fabric is expected to be far superior to nonwoven fabrics made of other materials for applications that require use under high-temperature conditions under corrosive conditions such as acids and alkalis. . However, liquid crystal polyester has the property that rigid molecules are aligned in the major axis direction to a high degree of molecular orientation, and it is difficult to fuse elongated fibers after making elongated fibers. , The strength was low and sufficient strength could not be obtained. Furthermore, by using rigid long fibers, the physical properties of the resulting nonwoven fabric sometimes have anisotropy. For example, JP-A-60-239600
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses a paper in which fibrillated liquid crystal polyester fibers are bonded, but the strength is not sufficient because there is no three-dimensional entanglement between fibrils.

From the viewpoint of maintaining strength, Japanese Patent Application Laid-Open No. 6-128857 discloses a method for producing a liquid crystal polyester long-fiber nonwoven fabric, which is uniformly and densely self-fused for maintaining strength. The structure is too dense and is not suitable for use in impregnating a resin or a solvent.
Japanese Patent Application Laid-Open No. 7-243162 describes a method for producing a nonwoven fabric using a liquid crystal polyester fiber produced by a melt spinning method. However, the liquid crystal polyester fiber obtained by this method has a rod-like shape and is poorly entangled. It is thought that it becomes necessary, and it requires heat treatment at a high temperature around the flow start temperature of special embossing rolls and liquid crystal polyester, and there are many steps from long fiber molding to final treatment, and there are many molding conditions complicated and expensive, In some cases, the balance of vertical and horizontal physical properties such as the breaking length was not good. Further, Japanese Patent Application Laid-Open
JP-A-31817 discloses a polyester nonwoven fabric containing a fibrillated liquid crystal polyester, but has a drawback that strength anisotropy is large.

[0004]

As described above, it has been difficult to produce a non-woven fabric which simultaneously satisfies the porosity, strength retention, and low anisotropy for utilizing the performance of the liquid crystal polyester as a non-woven fabric. When manufacturing such a nonwoven fabric, it was also difficult to control the basis weight to obtain a nonwoven fabric having a desired porosity.

In view of such circumstances, the problem to be solved by the present invention is to provide a liquid crystal polyester nonwoven fabric having a high porosity, a small strength anisotropy, and excellent in bending resistance, heat resistance and chemical resistance. It is an object of the present invention to provide a method for producing a liquid crystal polyester fiber with good characteristics, and a liquid crystal polyester fiber suitable for the method and a method for producing the same.

[0006]

According to the present invention, a thermoplastic resin (A) of a thermoplastic resin composition having a continuous phase of a thermoplastic resin (A) and a dispersed phase of a liquid crystal polyester (B) is used as a solvent. The present invention relates to a method for producing a liquid crystal polyester fiber which is dissolved and removed in water, and a liquid crystal polyester fiber obtained by the production method. Further, the present invention relates to a method for producing a liquid crystal polyester nonwoven fabric, in which liquid crystal polyester fibers obtained by the production method are dispersed in a liquid that does not substantially require liquid crystal polyester (B), paper is formed, and three-dimensionally bonded. Such is the case.

[0007]

Next, the present invention will be described in more detail. The thermoplastic resin (A) used in the present invention is a thermoplastic resin other than the liquid crystal polyester, which is soluble in a solvent such as water, an organic solvent, an acid, or an alkali. However, if the liquid crystal polyester (B) used at the same time can be used so as not to be substantially dissolved, the molecular structure is not particularly limited. Specific examples of the combination of the thermoplastic resin and the solvent include, but are not limited to, polyphenylene ether and chloroform, polycarbonate and chloroform, polystyrene and chloroform, polyether sulfone and NMP, and the like.

Among them, poly (2,6-dimethylphenylene ether) is preferred from the viewpoint of heat resistance during melt-kneading with the liquid crystal polyester (B), availability of resin, availability of solvent and versatility.
And chloroform, or a combination of polycarbonate (bisphenol A type) and chloroform.

The liquid crystal polyester (B) used in the present invention
Is a polyester called a thermotropic liquid crystal polymer.

Specifically, (1) a compound obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid.
(2) Those obtained by reacting a combination of different aromatic hydroxycarboxylic acids. (3) Those obtained by reacting an aromatic dicarboxylic acid with a nucleus-substituted aromatic diol. (4) Those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate. And those forming an anisotropic melt at a temperature of 400 ° C. or less are preferred. In addition, instead of these aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids, ester derivatives thereof may be used.

The repeating structural units of the liquid crystalline polyester include the following repeating structural units derived from an aromatic dicarboxylic acid, the following repeating structural units derived from an aromatic diol,
Examples of the repeating structural unit derived from an aromatic hydroxycarboxylic acid include, but are not limited to, these.

A repeating structural unit derived from an aromatic dicarboxylic acid:

[0013]

A repeating structural unit derived from an aromatic diol:

[0015]

A repeating structural unit derived from an aromatic hydroxycarboxylic acid:

A liquid crystal polyester which is particularly preferred from the balance of heat resistance, mechanical properties and workability is And more preferably at least 30 mol% or more of such a repeating structural unit. Specifically, the combination of repeating structural units is preferably any one of the following (I) to (VI).

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

The method for producing the liquid crystal polyesters (I) to (VI) is described in, for example, JP-B-47-47870.
JP-B-63-3888, JP-B-63-3891, JP-B-56-18016, JP-A-2-51
No. 523, etc. Of these, a combination of (I), (II) or (IV) is preferable, and a combination of (I) or (II) is more preferable.

In the field where high heat resistance is required in the present invention, the liquid crystal polyester of the component (A) contains 30 to 80 mol% of the following repeating unit (a ') and 0 to 100% of the repeating unit (b'). 10 mol%, repeating unit (c ') is 1
A liquid crystal polyester having 0 to 25 mol% and a repeating unit (d ') of 10 to 35 mol% is preferably used.

[0026]

The fields in which the liquid crystal polyester fiber or nonwoven fabric of the present invention requires easy disposal such as incineration after use from the viewpoint of environmental problems include the preferred combinations of the fields required in each of the above. In particular, a liquid crystal polyester formed of a combination of only carbon, hydrogen, and oxygen is particularly preferably used.

The thermoplastic resin composition according to the present invention comprises 70.0 to 90.0% by weight, preferably 7% by weight of the thermoplastic resin (A).
5.0-85.0% by weight, more preferably 78-83%
% By weight, and liquid crystal polyester (B) 30.0 to 1
0.0% by weight, preferably 25.0 to 15.0% by weight,
More preferably, it is a thermoplastic resin composition containing 22 to 17% by weight. If the content of the component (A) is less than 70% by weight, the dispersion particle size of the component (B) in the melt of the composition may become large or continuous, which is not preferable. On the other hand, if the content of the component (A) exceeds 90.0% by weight, the component (B) may not be formed into a long fiber even when the melt of the composition is stretched.

As a method for producing the thermoplastic resin composition in the present invention, a known method can be used. From an industrial point of view, a method of kneading each component of the above composition in a molten state is preferred. For the melt kneading, kneading apparatuses such as a single-screw or twin-screw extruder and various kneaders which are generally used can be used. In particular, a biaxial high kneader is preferred. At the time of melt-kneading, it is preferable to set the cylinder set temperature of the kneading device to a temperature higher than the flow start temperature of the component (B). If the cylinder set temperature is lower than the flow start temperature of the component (B), the component (B) does not sufficiently melt, and dispersion failure may occur, which is not preferable. Here, the flow start temperature is measured by a capillary rheometer (eg, a flow tester CFT-500 manufactured by Shimadzu Corporation) and measured at 4 ° C.
Resin heated and melted at a heating rate of
When extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under gf / cm ² , a temperature (° C.) at which the melt viscosity shows 48,000 poise.

At the time of kneading, the respective components may be previously mixed uniformly using a device such as a tumbler or a Henschel mixer, or if necessary, the mixing may be omitted, and each component may be separately supplied to the kneading device. Methods can also be used.

The thermoplastic resin composition used in the present invention comprises:
If necessary, organic fillers, antioxidants, heat stabilizers, light stabilizers, flame retardants, lubricants, antistatic agents, rust inhibitors, crosslinkers,
Various additives such as a foaming agent, a fluorescent agent, a surface smoothing agent, a surface gloss improving agent, and a mold release improving agent such as a fluororesin can be used in the production process or in the subsequent processing process.

The liquid crystal polyester fiber of the present invention is obtained by treating the above-mentioned thermoplastic resin composition with the above-mentioned solvent, and dissolving and removing the thermoplastic resin (A) in the solvent. The morphology of the thermoplastic resin composition treated with the solvent is preferably such that the liquid crystal polyester (B) is fibrous. The thermoplastic resin composition containing the fibrous liquid crystal polyester (B) can be suitably obtained by stretching and solidifying a melt of the above thermoplastic resin composition.

The stretching of the melt of the above thermoplastic resin composition is performed by extruding the thermoplastic resin composition from a nozzle attached to the tip of a single-screw or twin-screw extruder and stretching it with a commercially available strand cutter or the like. be able to. The stretching ratio (drawing speed by a strand cutter / discharge speed from a nozzle) is preferably 3 times or more. If the ratio is less than 3 times, the component (B) is not sufficiently stretched in the melt, and the fibrous component (B) may not be obtained, which is not preferable. The stretched molten resin is usually cooled and solidified by a method such as air cooling or water cooling to obtain a thread-like thermoplastic resin composition. Such a thread-like thermoplastic resin composition may be used as it is, or may be cut into pellets using a strand cutter or the like. In the present invention, it is preferable to use pellets because the subsequent treatment is easy. The temperature at which the thermoplastic resin composition is melted is preferably higher than the flow start temperature of the liquid crystal polyester (B).

When the thermoplastic resin (A) is dissolved in the solvent, it is preferable that the solvent can be recovered by evaporating and then cooling it from the viewpoints of environmental problems and costs. The type of the solvent is selected according to the type of the component (A), and specific examples are as described above.

The liquid crystal polyester fiber thus obtained is usually sufficiently washed with the solvent used for dissolving and removing the thermoplastic resin (A), and then converted into a liquid in which the liquid crystal polyester (B) is substantially insoluble. A liquid crystal polyester non-woven fabric can be manufactured by dispersing and forming into a paper shape by a papermaking method and then three-dimensionally bonding.

The liquid in which the liquid crystal polyester (B) is substantially insoluble is water having a viscosity of 1.0 c
Those having a viscosity (20 ° C.) higher than p (centipoise) are preferably used. When the viscosity of the liquid is low, the fibrous liquid crystal polyester (B) is aggregated,
The dispersion in the dispersion may not be uniform, which is not preferable. Specifically, ethylene glycol (21 cp),
Glycerin (1500 cp), a mixed solution of ethylene glycol and water, a mixed solution of ethylene glycol and ethanol, and the like are preferably used. Ethylene glycol is particularly preferably used.

The liquid crystal polyester fiber dispersed in the liquid is formed into a paper by a paper making method. At this time, the thickness can be changed by changing the amount of the dispersion, the papermaking method (the number of times of scooping), the composition ratio and the viscosity of the dispersion, and the basis weight can be controlled. For example, when the amount of the dispersion is large or the viscosity of the dispersion is low, the spread of the fibrous liquid crystal polyester in the dispersion becomes large, and the basis weight decreases.
In the present invention, the controllability of the basis weight is good, and a nonwoven fabric having a wide range of porosity can be obtained.

The paper-like liquid crystal polyester (B) obtained by papermaking can be made into a non-woven fabric by three-dimensionally bonding, but it is preferable to treat by heat and / or pressure. Pressure is 100
Kg / cm ² or less is more preferable, and if it is more than this, the porosity may be too small, which is not preferable. The temperature is more preferably lower than the flow start temperature of the liquid crystal polyester (B). If heat treatment is performed at a temperature higher than the flow start temperature, the fibrous liquid crystal polyester (B) melts, which is not preferable. Preferably, the pressure is 100 kg / cm ²
In this case, a temperature lower than the flow start temperature of the component (B) by 150 ° C. or more is used. At a pressure of 50 kg / cm ² , a temperature lower than the flow start temperature of the component (B) by 100 ° C. or more is used.

The thickness and shape of the nonwoven fabric according to the present invention can be freely selected.

The nonwoven fabric of the present invention can be used alone, or can be used by laminating or bonding with other thermoplastic resin films, nonwoven fabrics, woven fabrics and the like.

The surface of the nonwoven fabric of the present invention can be subjected to a surface treatment as required. Examples of such a surface treatment method include corona discharge treatment, plasma treatment, flame treatment, sputtering treatment, solvent treatment, ultraviolet treatment, infrared treatment, ozone treatment, and polishing treatment.

[0042]

EXAMPLES The present invention will be described below with reference to examples, but these are merely examples, and the present invention is not limited to these examples.

(1) Thermoplastic resin of component (A) Commercially available polycarbonate manufactured by Sumitomo Dow KK
CALIBRE 200-4 was used. Hereinafter, the thermoplastic resin is abbreviated as A-1.

(2) Liquid crystal polyester of component (B) (i) 8.3 kg (60 mol) of p-acetoxybenzoic acid, 2.49 kg (15 mol) of terephthalic acid, 0.83 kg (5 mol) of isophthalic acid and 4 5,45 kg (20.2 mol) of 4,4'-diacetoxydiphenyl was charged into a polymerization tank having a comb-shaped stirring blade, and the temperature was increased while stirring under a nitrogen gas atmosphere, and polymerization was performed at 330 ° C. for 1 hour. The acetic acid gas produced as a by-product during this period was polymerized under strong stirring while being liquefied and collected and removed by a cooling tube. Thereafter, the system was gradually cooled, and the polymer obtained at 200 ° C. was taken out of the system.
The obtained polymer was pulverized with a hammer mill manufactured by Hosokawa Micron Co., Ltd. to obtain particles of 2.5 mm or less. This is further heated at 280 ° C. in a rotary kiln under a nitrogen gas atmosphere.
For 3 hours, the flow start temperature becomes 324.
A wholly aromatic polyester comprising the following repeating structural units in the form of particles at a temperature of ° C was obtained. Here, the flow start temperature is measured with a flow tester CFT-500 manufactured by Shimadzu Corporation.
The resin heated and melted at a heating rate of 4 ° C./min is loaded with a load of 10
Under 0 kgf / cm ^2, an inner diameter of 1 mm, length 10mm
When extruded from the nozzle, the melt viscosity is 48000
A temperature (° C.) indicating poise. Hereinafter, the liquid crystal polyester is abbreviated as B-1. The polymer is 340 under pressure
It showed optical anisotropy at a temperature of at least ° C. Liquid crystal polyester B-1
Are as follows.

[0045]

(Ii) p-hydroxybenzoic acid 16.6
kg (12.1 mol) and 8.4 kg (45 mol) of 6-hydroxy-2-naphthoic acid and 18.6 kg of acetic anhydride
(182 mol) was charged into a polymerization vessel equipped with a comb-shaped stirring blade, and the temperature was increased while stirring under a nitrogen gas atmosphere, and the polymerization was performed at 320 ° C. for 1 hour, and further at 320 ° C. for 1 hour under a reduced pressure of 2.0 torr. Was. During this time, acetic acid produced as a by-product was continuously distilled out of the system. Thereafter, the system was gradually cooled, and the polymer obtained at 180 ° C. was taken out of the system. The obtained polymer is pulverized in the same manner as in the above (B-1), and then treated in a rotary kiln under a nitrogen gas atmosphere at 240 ° C. for 5 hours to obtain a particulate starting material having a flow start temperature of 270 ° C. A wholly aromatic polyester consisting of repeating units was obtained. Hereinafter, the liquid crystal polyester is abbreviated as B-2. This polymer showed optical anisotropy at 280 ° C. or more under pressure. The ratio of the repeating structural units of the liquid crystal polyester B-2 is as follows.

[0047]

(3) Measurement method of physical properties (i) Porosity: The apparent specific gravity was converted from the weight and the volume of the sample piece, and the porosity was calculated by comparing the liquid crystal polyester as a raw material.

(Ii) Breaking length: JIS P813-1
It was measured according to the 976 standard.

(Iii) Flex resistance: A sample of a liquid crystal polyester nonwoven fabric in a direction perpendicular to the liquid crystal polyester was cut out, and each was subjected to a MIT flex tester Foldi manufactured by Toyo Seiki Co., Ltd.
Using ngEndurance Tester MIT-D type, load 1 kg based on JIS-p-8115
f, bending angle 135 degrees, bending surface curvature radius 1m
m, a bending test was performed at a bending speed of 175 times / min.
The number of times of bending until the film or sheet was broken was determined.

Reference Example 1 80% by weight of A-1 and 20% by weight of B-1 were melted at a cylinder set temperature of 340 ° C. and a screw rotation speed of 200 rpm using a TEX-30 type twin screw extruder manufactured by Nippon Steel Corporation. The composition was obtained by kneading. Extruded from a circular nozzle, the discharge speed was 7.0 m / min. With a plasticizer manufactured by Hoshi Plastics Co., Ltd., the take-up speed is 35m
/ Min, and pelletized at the same time. 10 g of pellets of this composition were added to chloroform heated to 60 ° C. in a 2 L flask, and stirred for 1 hour to dissolve the polycarbonate. The insoluble components were collected by filtration through a # 200 wire mesh, and 6
Washed well with chloroform at 0 ° C. This operation was repeated until the required amount of insoluble components was obtained. This insoluble component is abbreviated as C-1.

Reference Example 2 The same operation as in Reference Example 1 was carried out except that A-1 was 92% by weight and B-1 was 8% by weight. The obtained insoluble component is abbreviated as C-2.

Reference Example 3 The same operation as in Reference Example 1 was carried out except that A-1 was 68% by weight and B-1 was 32% by weight. The obtained insoluble component was C-3
Abbreviated.

Reference Example 4 A take-up speed of 14 m / min. Reference example 1 except for
The same operation was performed. The obtained insoluble component is abbreviated as C-4.

Reference Example 5 The procedure of Reference Example 1 was repeated except that A-1 was 85% by weight and B-2 was 15% by weight, and the cylinder set temperature was 280 ° C. The obtained insoluble component is abbreviated as C-5.

Reference Example 6 The procedure of Reference Example 1 was repeated except that A-1 was 60% by weight and B-2 was 40% by weight, and the cylinder set temperature was 280 ° C. The obtained insoluble component is abbreviated as C-6.

Example 1 After drying C-1 obtained in Reference Example 1, 4 g of C-1 was added to 800
g of ethylene glycol, sufficiently stirred and dispersed using a mixer, and slowly filtered through a horizontal 1 μm Teflon filter using a level. After the completion of the filtration, the paper-like sample obtained by carefully peeling off the Teflon filter was dried and hot-pressed at 150 ° C. and 50 kgf / cm ² for 2 minutes. The thickness of the obtained nonwoven fabric is 50μ.
m, the porosity is 60% (basis weight 27.7 g / m ² ), the average breaking length measured by sampling in two orthogonal directions is 5.4 Km and 5.2 Km, respectively. (5.4 / 5.2) was 1.04, and almost no anisotropy was recognized. The bending test did not break after 50,000 times. When this sample was carefully sampled so as not to damage the tissue and observed with an electron microscope, it was observed that long fibrous liquid crystal polyesters were three-dimensionally entangled and bonded (FIGS. 1 and 2).

Comparative Example 1 Using C-2 obtained in Reference Example 2, a paper-like sample obtained in the same manner as in Example 1 was dried.
It was hot pressed at gf / cm ² for 2 minutes. The obtained sample was brittle and could not be measured in the breaking length test and the bending test. When this sample was carefully sampled so as not to damage the tissue and observed with an electron microscope, it was observed that the rugby ball-shaped and short fibrous liquid crystal polyester as shown in FIG. 3 were almost independent.

Comparative Example 2 Using C-3 obtained in Reference Example 3, a paper sample obtained in the same manner as in Example 1 was dried.
It was hot pressed at gf / cm ² for 2 minutes. The thickness of the obtained nonwoven fabric is 33 μm, and the porosity is 27% (basis weight 33.4 g / m 2).
² ) The breaking length measured by sampling in two orthogonal directions was 1.5 Km and 1.2 Km, respectively, and varied. The anisotropy ratio was as large as 1.25. In the bending test, it was broken about 5000 times. When this sample was carefully sampled so as not to damage the tissue, and observed with an electron microscope, it was found that not all of the sample had a fibrous shape and that a non-homogeneous lumpy liquid crystal polyester as shown in FIG. 4 was present. Was observed.

Comparative Example 3 Using C-4 obtained in Reference Example 4, a paper-like sample obtained in the same manner as in Example 1 was dried.
It was hot pressed at gf / cm ² for 2 minutes. The thickness of the nonwoven is 6
It was 0 μm, the porosity was 51%, and it was brittle and the measurement of the breaking length was difficult, but it was about 1.6 km or less. By observation with an electron microscope, a structure close to Comparative Example 1 (FIG. 3) was observed.

Example 2 After drying C-5 obtained in Reference Example 5, C-5 was added in a weight of 200
It was dispersed in 1-fold ethylene glycol and filtered through a 1 μm Teflon filter. The obtained paper-like sample was dried and hot-pressed at 90 ° C. and 50 kgf / cm ² for 2 minutes. The thickness of the obtained nonwoven fabric is 65 μm, and the porosity is 55%.
(Basis weight 55.6 g / m ² ), the breaking length measured by sampling in two orthogonal directions was 6.9 km, respectively.
7.0 Km, the anisotropy ratio was 1.01, and almost no anisotropy was observed. The bending test is 50,000
It did not break more than once. As a result of observation with an electron microscope, a structure in which fibrous liquid crystal polyester was intertwined three-dimensionally was observed.

Comparative Example 4 After drying C-6 obtained in Reference Example 6, C-6 was added in a weight of 200
It was dispersed in 1-fold ethylene glycol and filtered through a 1 μm Teflon filter. The obtained paper-like sample was dried and hot-pressed at 90 ° C. and 50 kgf / cm ² for 2 minutes. The thickness of the obtained nonwoven fabric is 33 μm, and the porosity is 28%.
(Basis weight 45.1 g / m ² ), the breaking length measured by sampling in two orthogonal directions was 2.0 Km, respectively.
It was 1.8 km, and variation was observed. The anisotropy ratio was 1.11. In the bending test, it was broken about 3000 times. By observation with an electron microscope, a structure close to that of Comparative Example 1 was observed.

[0063]

According to the method for producing a liquid crystal polyester nonwoven fabric of the present invention, a nonwoven fabric having good heat resistance, chemical resistance, anisotropy and the like can be produced with excellent control of the basis weight. In addition to being excellent in air permeability, a nonwoven fabric having a small anisotropy in the breaking length and excellent in flexibility can be obtained. Therefore, an excellent non-woven fabric can be produced which retains the inherent chemical resistance and heat resistance of the liquid crystal polyester. This can make a significant contribution to a wide range of industries such as filters, separators, and inner materials for clothes. Further, according to the method for producing a liquid crystal polyester fiber of the present invention, a liquid crystal polyester fiber suitable for producing such a liquid crystal polyester nonwoven fabric can be produced.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of the surface of the nonwoven fabric of Example 1 obtained from a composition of A-1 / B-1 = 80/20. 5000
Times.

FIG. 2 is an electron micrograph of the surface of the nonwoven fabric of Example 1 obtained from a composition of A-1 / B-1 = 80/20. 200 times.

FIG. 3 is an electron micrograph of the surface of a sample of Comparative Example 1 obtained from a composition of A-1 / B-1 = 92/8. 1000 times.

FIG. 4 is an electron micrograph of the surface of a nonwoven fabric of Comparative Example 2 obtained from a composition of A-1 / B-1 = 68/32. 500 times.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) D04H 3/14 D04H 3/14 Z D21H 13/24 D21H 13/24 D06M 5/08 F term (reference) 4L031 AA18 AB01 AB34 BA31 CA08 CA11 DA00 DA17 4L035 BB40 CC20 FF05 HH10 MC04 4L047 AA21 BA21 BD04 CB01 CB05 CB10 CC01 CC12 4L055 AF33 AF44 AF47 AG88 BE20 EA25 EA32 EA40 FA11 FA19 FA23 GA39

Claims (12)

[Claims] (1) 70.0 to 90.0% by weight of a thermoplastic resin (A) and 30.0 to 10.0 of a liquid crystal polyester (B).
% Of the thermoplastic resin (A) having a continuous phase and a liquid crystal polyester (B) forming a dispersed phase, and a melt of the thermoplastic resin composition is stretched three times or more and solidified. A method for producing a liquid crystal polyester fiber, wherein A) is dissolved in a solvent and removed. 2. A thermoplastic resin (A) of 70.0 to 90.0% by weight and a liquid crystal polyester (B) of 30.0 to 10.0.
Wt%, and the thermoplastic resin (A) melts the thermoplastic resin composition in which the continuous phase forms the dispersed phase with the liquid crystal polyester (B), and is extruded from the nozzle.
A method for producing a liquid crystal polyester fiber, comprising: stretching at a take-up speed of twice or more, cooling and solidifying, and then dissolving and removing the thermoplastic resin (A) in a solvent. 3. The temperature at which the thermoplastic resin composition is melted,
3. The method for producing a liquid crystal polyester fiber according to claim 1, wherein the temperature is higher than a flow start temperature of the liquid crystal polyester (B). Here, the flow start temperature is
When a resin measured by a capillary rheometer and heated and melted at a heating rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 100 kgf / cm ² , a melt viscosity is obtained. Refers to a temperature (° C.) at which 48,000 poise is exhibited. 4. The method for producing a liquid crystal polyester fiber according to claim 1, wherein the thermoplastic resin (A) is polycarbonate or poly (2,6-dimethylphenylene ether). 5. The method according to claim 4, wherein the solvent used for dissolving and removing the thermoplastic resin (A) in the solvent is chloroform. 6. The method for producing a liquid crystal polyester fiber according to claim 1, wherein the liquid crystal polyester (B) contains at least 30 mol% of the following repeating structural units. 7. The liquid crystal polyester (B) according to claim 1, which is obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. The method for producing the liquid crystal polyester fiber according to the above. 8. The liquid crystal polyester fiber according to claim 1, wherein the liquid crystal polyester (B) is obtained by reacting a combination of different kinds of aromatic hydroxycarboxylic acids. Production method. 9. A liquid crystal polyester fiber obtained by the production method according to claim 1. 10. A paper made by dispersing a liquid crystal polyester fiber obtained by the production method according to any one of claims 1 to 8 in a liquid in which the liquid crystal polyester (B) is substantially insoluble. A method for producing a liquid crystal polyester non-woven fabric, characterized in that the non-woven fabric is bonded to 11. A paper made by dispersing a liquid crystal polyester fiber obtained by the production method according to any one of claims 1 to 8 in a liquid in which the component (B) is liquid crystal polyester. Alternatively, a method for producing a liquid crystal polyester nonwoven fabric, wherein the nonwoven fabric is bonded three-dimensionally by pressure. 12. A liquid in which the liquid crystal polyester (B) is substantially insoluble is a liquid having a viscosity (20 ° C.) higher than 1.0 cp, wherein the liquid crystal polyester (B) is substantially insoluble. The method for producing a liquid crystal polyester nonwoven fabric according to claim 10 or 11, wherein: