JPH06166909A - Production of melt anisotropic aromatic polyester ultrafine fiber - Google Patents

Abstract

PURPOSE:To obtain melt anisotropic aromatic polyester ultrafine fiber having a high strength and elastic modulus, especially fiber of <=3 denier size. CONSTITUTION:A melt anisotropic aromatic polyester fiber (TLC) having <500P melt viscosity (temperature: Tm+20 deg.C; shearing rate: 1000 sec<-1>) is discharged from a spinneret) having $ 0.10 mm diameter, and kept at a higher temperature thereof than the melting point of the TLC by >=15 deg.C. The temperature of the fiber at a point separated from the nozzle surface after the discharge by 30cm is regulated to a lower temperature than the melting point of the TLC by >=150 deg.C and wound at >=20 draft ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stably spinning ultrafine fibers of aromatic polyester capable of forming an anisotropic melt phase and having high strength and high elastic modulus.

[0002]

2. Description of the Related Art Ultrafine fibers are widely industrially manufactured for artificial leather, various kinds of fabrics (for example, silk-like fabrics), wiping cloths, filters and the like for clothing and industry. This type of filament type ultrafine fiber is roughly classified into a direct spinning method and a composite spinning method. Direct spinning (also referred to as direct spinning) is a method in which the amount of polymer discharged per hole provided in a spinneret is minimized and spinning is performed, followed by high drawing. The composite spinning method includes the sea-island type composite spinning method in which after the sea-island type fiber is spun, the sea component is eluted with a solvent or decomposed and removed by a decomposing agent to obtain only the island component as ultrafine fibers, two or more incompatible components. There is a peeling type (divided type, multi-layer type) composite spinning method in which a composite fiber made of a polymer is spun, and then the polymer is divided into pieces by the action of a chemical solution or an impact to obtain ultrafine fibers. On the other hand, it is notable that the melt-anisotropic aromatic polyester, which is easily melt-processed, is made into fibers by extruding it from the spinneret at a temperature equal to or higher than the melting point, and it is possible to further improve the physical properties of the fiber filaments by heat treatment. It is publicly known in Japanese Laid-Open Patent Publication No. 54-77691, Japanese Patent Publication No. 1-174408, and the like.

[0003]

The above-mentioned method of composite spinning (sea-island type, peeling type) requires a special spinneret with a complicated structure at the stage of melt spinning, and because of elution and splitting, etc. However, there is a problem that the cost becomes extremely high in industrial production due to the necessity of the special process of.
On the other hand, the direct spinning method has an advantage that the cost is low because the thermoplastic polymer may be spun from an ordinary spinneret, but in the case of the melt anisotropic aromatic polyester, the breaking elongation is low. After spinning like a normal thermoplastic polymer,
It is virtually impossible to stretch at a high magnification. For this reason, it has not been possible to operatively and stably manufacture a single fiber having a small denier (particularly, 3 denier or less). The present inventors have found the present invention as a result of intensive research on a method capable of stably spinning ultrafine fibers made of an aromatic polyester capable of forming an anisotropic melt phase.

[0004]

The present invention is directed to an aromatic polyester (hereinafter abbreviated as TLC) capable of forming an anisotropic melt phase.
In the melt spinning method, in which is discharged from a nozzle having a pore with a diameter of 0.1 mm or less and spun and wound, the following conditions are used: -as the TLC, the melting point of the TLC (hereinafter abbreviated as Tm)
A polymer having a melt viscosity (hereinafter abbreviated as MV) at a shear rate of 1000 sec ⁻¹ of + 20 ° C. of less than 500 poise is used, and a shear rate (γ) when passing through a nozzle is 10 ³ to 10 ⁹ (se).
c ⁻¹ ), and the discharge linear velocity (hereinafter abbreviated as V ₀ ) at the nozzle is 5 m
/ Min or more and 40 m / min or less, and a winding speed (hereinafter abbreviated as V ₁ ) of 150 m / min or more and 80
The ratio of the winding speed to the discharge linear velocity (V ₁ / V ₀ ) is 20 or more, and the spinneret temperature (hereinafter abbreviated as T ₁ ) is Tm + 15 ° C. or more. The temperature of the fiber (hereinafter abbreviated as T ₂ ) at a point 30 cm away from the nozzle surface after discharge is set to Tm-150 ° C. or less. It is a manufacturing method.

The aromatic polyester (TLC) capable of forming the anisotropic melt phase used in the present invention is, for example, a polymer obtained from aromatic diol, aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid, etc. Include polymers comprising a combination of repeating constitutional units shown in Chemical formulas 1 and 2.

[0006]

[Chemical 1]

[Chemical 2]

Particularly preferably, (A) shown in Chemical formula 3
Aromatic polyester in which the proportion of the constituent unit of (B) is 60 mol% or more, and particularly the aromatic polyester in which the component (B) is 5 to 45 mol% with respect to the total amount of (A) and (B) is preferable.

[0008]

[Chemical 3]

The components contain other polymers or additives (pigments, carbon, heat stabilizers, UV absorbers, lubricants, optical brighteners, etc.) within the range in which their strength is not substantially reduced. Is also good. One of the features of the present invention is to use a resin having a melting point (Tm) of TLC + 20 ° C. and a melt viscosity MV at a shear rate of 1000 sec ⁻¹ of less than 500 poise,
The shear rate (γ) when passing through the spinneret was discharged at 10 ³ <γ <10 ⁹ (sec ⁻¹ ) and the condition at the nozzle was 40 ≧ V ₀ ≧ 5 (m / min) 8000 ≧ V ₁ ≧ 150 DF ≧ 20 within the allowable range of (m / min) (draft: DF = V ₁ / V ₀ ).
To do so.

In the case of the TLC, since it is difficult to draw the TLC in the post-process after the winding and winding as described above, it is important to discharge the molten resin from the pores as much as possible.
For that purpose, it is necessary to use fine pores having a diameter of 0.1 mm or less and to pass the TLC continuously through fine pores without breaking the yarn. As described above, strict properties are required for the flow characteristics at the time of melting required for TLC. That is, when the melt viscosity η at a melting point of TLC + 20 ° C. and a shear rate of 1000 sec ⁻¹ is 500 poise or more, the melt fluidity is lowered, and many yarn breakages occur at the pore outlets, which does not satisfy the gist of the present invention. There is. The shear rate when passing through the spinneret was 10 ³ <γ <10 ⁹ (sec ⁻¹ ), and the nozzle condition was 4
0 ≧ V ₀ ≧ 5 (m / min), the winding speed condition is 8
It is necessary to set the spinning draft (abbreviated as DF), that is, V ₁ / V ₀ to DF ≧ 20 in the range of 000 ≧ V ₁ ≧ 150 (m / min). If this condition is not satisfied, the orientation of the molecules will be insufficient, fine denier will not be obtained, and the desired ultrafine fibers of high strength and high elastic modulus will not be obtained.

The method of measuring the melting point Tm referred to in the present invention will be described below. DSC (for example TA300 manufactured by Mettler)
0) 10 to 20 mg of a sample was taken in the apparatus, sealed in an aluminum pan, and then nitrogen was flowed at 50 cc / min, and the temperature was measured at a temperature rising rate of 20 ° C./min. Depending on the type of polymer, 1st-r
In some cases, no clear endothermic peak appears in un. In that case, at a temperature rising rate of 50 ° C./min, the temperature is 50 ° C. or more higher than the expected endothermic peak temperature for about 3 minutes to completely melt, and then cooled to 50 ° C. at 80 ° C./min.
After that, it is preferable to measure at a temperature rising rate of 20 ° C./min.

The shear rate (γ) referred to in the present invention means the nozzle radius is r (cm), and the polymer discharge amount per single hole is Q.
When it is (cm ³ / sec), γ = 4Q / πr ³ is calculated. However, when the nozzle cross section is not a circle, r is the radius of the circle corresponding to the cross-sectional area.

The second feature of the present invention is that the spinneret temperature T
1 and the fiber temperature T2 at a time of 30 cm away from the nozzle surface after discharge, T1 ≧ Tm + 15 (° C.) and Tm−150
≧ T2 (° C.). In melt spinning, melted TLC is discharged from the spinneret and then cooled and solidified to be taken up. In ultrafine fiber production, the discharge amount per single hole is usually kept to 0.5 g / min or less, so the heat capacity of the discharge yarn is small and the spinneret is small. Since it is cooled in the vicinity, denier spots and fiber physical property spots tend to become large. In particular, when it is severe, yarn breakage or fusion occurs frequently, resulting in inability to manufacture.
This effective measure is strict temperature control of the spinneret,
It is important to suppress the melt viscosity unevenness of the polymer melt due to the temperature unevenness of the die. As a result, the discharge amount between the discharge holes became uniform, and the denier unevenness was minimized.

The specific spinneret temperature T1 is Tm + 15 ° C.
As a method of controlling the above, there is a method of stabilizing the spinneret temperature by controlling the temperature of the spinning machine or a method of stably controlling the spinneret temperature by installing an independent heater outside the spinneret. Generally, in the former case, when controlling the spinneret temperature to Tm + 15 ° C. or higher, the spinning machine body temperature needs to be further increased to 5 to 10 ° C. or higher. It is unsuitable because it causes frequent occurrence of screws or thread breakage. In particular, when the difference between the TLC decomposition start temperature Td and the melting point Tm is close to less than 100 ° C., the latter independent heater that can suppress the thermal decomposition of TLC during residence in the spinning machine is preferable. Here, the decomposition start temperature Td is 10 ° C./mi in a nitrogen atmosphere.
It is the weight loss onset temperature in the TG curve (thermogravimetric curve) measured by n. The equipment used in the present invention is a differential type differential thermal balance manufactured by Rigaku Denki Co., Ltd.

In the case of the ultrafine fibers of the TLC, since the diameter of the single fibers becomes small, gradually cooling causes unevenness in the thickness of the fibers and frequent breakage of the fibers. Therefore, the temperature T2 at the time of 30 cm away from the nozzle surface after ejection is Tm-1.
It is preferable to perform rapid cooling so as to maintain a temperature of 50 ° C. or lower. Further preferably, Tm-200 ° C. or lower is preferable.

It is preferable to install a cooling air blowing device for the purpose of positive cooling. The cooling device may be a method of blowing the fiber bundle from one direction or two or more directions on the outer circumference, a method of blowing the fiber bundle from the inside, a method of supplying cooling air in a form of wrapping the circumference of the fiber bundle in an annular shape. Available.

For the purpose of uniformly cooling the fiber bundle, it is preferable to use a cooling air dispersion device such as a filter, a straightening plate, or a wire net at the cooling air supply port.

Melt-spun fiber (original yarn) according to the present invention
Is 0.1-5.0 denier for single fiber and 5-40g for strength
/ D. The spun raw yarn may be used as it is, but in some cases, the fiber performance such as strength and elastic modulus can be improved by performing the following heat treatment. When a medium such as gas is used, heat can be supplied by using radiation from a heating plate, infrared heater, etc., by contacting with a heat roller, plate, etc., internal heating method using high frequency, etc. . As the gas used as the heating medium, an inert gas such as nitrogen, a mixed gas of nitrogen and oxygen, carbon dioxide gas, or air is used. The heat treatment atmosphere has a dew point of -20.
A gas of ℃ or less, preferably -40 ℃ or less is good.

The heat treatment may be carried out under tension or without tension depending on the purpose. Further, the shape is a mould-like shape, a cheese-like shape, a tow-like shape (processed on a wire net), or between rollers. The preferable heat treatment temperature condition is Tm-6.
A pattern in which the temperature is sequentially increased from Tm-40 ° C in a range of 0 ° C to Tm + 20 ° C (where Tm is the melting point of the TLC described above) is more preferable. The heat treatment time can be several seconds to several tens hours depending on the desired performance.

The ultrafine fibers obtained by the present invention are widely used for clothing and industrial materials. Used for clothing, various work clothes, sports clothing, protective clothing, and industrial materials such as wiping cloth, various filters, various tension members, cords, mats, tents, rods, protective materials or protective sheets. It

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

EXAMPLES The logarithmic viscosity described in the examples and comparative examples was measured as follows. [Measurement of Logarithmic Viscosity] A sample was dissolved in pentafluorophenol in an amount of 0.1% by weight (60 to 80 ° C.), and a relative viscosity (ηrel) was measured by an Ubbelohde viscometer in a constant temperature bath at 60 ° C. Calculated by ηinh = ln (ηrel) / c where c is the polymer concentration (g / dl).

Example 1 As an aromatic polyester capable of forming an anisotropic melt phase, TLC having the above structural units (A) and (B) in a 73/27 mol% ratio was used. The physical properties of this TLC are: ηinh = 4.98 dl / g MV = 450 poise Tm = 280.3 ° C. This polymer was dried in a vacuum dryer at 140 ° C. for 10 hours, then extruded from a single-screw vent extruder and filtered with a filter having an average pore diameter of 5 μm consisting of a sand (stainless powder) layer and a fine metal wire, and then a nozzle diameter of 0. .0
By using a spinneret with 8 mm and 50 holes, an independent heater was installed outside the spinneret, and T1 was 320 ° C., and the temperature T2 of the fiber at a location 30 cm away from the nozzle surface after discharge was air-cooled from the outer circumference of the fiber to 50. Spinning was carried out under the condition of becoming ° C. Here, the temperatures of T1 and T2 are values measured by a non-infrared detection type non-contact thermometer. At this time, the shear rate γ, the discharge linear velocity V ₀ and the winding velocity V ₁ are γ = 3.50 × 10 ⁴ (sec ⁻¹ ) V ₀ = 21 (m / min) V ₁ = 770 (m / min) DF = 36.7. The obtained spun raw yarn was continuously wound on a stainless perforated bobbin covered with a cushioning material (thickness: 12.5 mm) made of an inorganic fiber and wound at a winding density of 0.60 g / cm ³ to about 6 kg. The product was heat-treated in a nitrogen atmosphere at 150 ° C. for 1 hour, 200 ° C. for 4 hours, and 280 ° C. for 11 hours. The mechanical properties of the heat treated yarn obtained are shown in Table 1 and below. Denier (DR): 75 dr / 50 f (1.5 dr per single fiber) Strength (DT): 30.5 g / d Elongation (DE): 4.2% Elastic modulus (YM): 594 g / d

Example 2 Using the TLC used in Example 1, the winding speed was 1440 m.
The spinning was performed under the same conditions as in Example 1 except that the speed was changed to / min. γ = 3.50 × 10 ⁴ (sec ⁻¹ ) V ₀ = 21 (m / min) V ₁ = 1440 (m / min) DF = 68.6 The obtained spun raw yarn was continuously subjected to the same conditions as in Example 1. Heat treated in. The mechanical properties of the heat treated yarn obtained are shown in Table 1 and below. Denier (DR): 40 dr / 50 f (0.8 dr per single fiber) Strength (DT): 31.3 g / d Elongation (DE): 4.3% Elastic modulus (YM): 596 g / d

Comparative Example 1 Spinning was performed under the same TLC and the same conditions as in Example 1 except that a 50-hole spinneret with a nozzle diameter of 0.15 mm was used. Frequent,
It could not be made into fibers. γ = 5.31 × 10 ³ (sec ⁻¹ ) V ₀ = 6 (m / min) V ₁ = 200 (m / min) DF = 33.3 Therefore, the discharge rate was doubled and spinning was performed. . But,
When the winding speed was 550 m / min or more, yarn breakage occurred frequently, and it was not possible to form fibers. γ = 1.06 × 10 ⁴ (sec ⁻¹ ) V ₀ = 12 (m / min) V ₁ = 550 (m / min) DF = 45.8 The denier of the spinning raw yarn is 213 dr / 50 f (4 per single fiber). .26 dr), and Table 1 shows the fiber performance of heat treatment under the same conditions as in Example 1.

Comparative Example 2 A TLC having the same composition (A) and (B) as in Example 1 but having a different degree of polymerization of 73/27 mol% was used. This T
The physical properties of LC are ηinh = 6.54 dl / g MV = 610 poise Tm = 280.5 ° C. This TLC was spun under the same conditions as in Example 1, but when the winding speed was increased to 350 m / min or more, yarn breakage occurred frequently and it was not possible to form fibers. γ = 3.50 × 10 ⁴ (sec ⁻¹ ) V ₀ = 21 (m / min) V ₁ = 250 (m / min) DF = 11.9 Denier of the spinning base yarn is 234 dr / 50 f (4 per single fiber) 0.68 dr), and the fiber performance of heat treatment under the same conditions as in Example 1 is shown in Table 1.

Comparative Example 3 The same TLC as in Comparative Example 2 was used and spun under the same nozzle with a slightly reduced shear rate.
It was not possible to obtain fibers of 34 dr or less. γ = 6.83 × 10 ⁴ (sec ⁻¹ ) V ₀ = 41 (m / min) V ₁ = 700 (m / min) DF = 17.1 The denier of the spinning base yarn is 167 dr / 50 f (3 per single fiber). .34 dr), and the fiber performance of heat treatment under the same conditions as in Example 1 is shown in Table 1.

Comparative Example 4 The temperature T2 of the fiber at a position 30 cm away from the nozzle after discharge was adjusted to 150 ° C. (T) by adjusting the amount of cooling air.
m-133 ° C.) was used, and the same TLC as in Example 1 was used and spun under the same conditions. However, the following conditions are the limits due to screw loss and yarn breakage that are considered to be caused by denier unevenness, Fibers below 3.00 dr could not be obtained. γ = 3.50 × 10 ⁴ (sec ⁻¹ ) V ₀ = 21 (m / min) V ₁ = 370 (m / min) DF = 17.6 The denier of the spinning yarn is 158 dr / 50 f (3 per single fiber). .16 dr), and the fiber performance after heat treatment under the same conditions as in Example 1 is shown in Table 1.

[0028]

[Table 1]

[0029]

According to the method of the present invention, it has hitherto been possible to stably produce an ultrafine fiber having a denier of 3 denier or less from an aromatic polyester capable of forming an anisotropic melt phase (that is, causing troubles such as yarn breakage and fuzz formation). It was possible to be able to manufacture it, though it was difficult to manufacture.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D01F 6/62 308 7199-3B

Claims (1)

[Claims] 1. A melt spinning method in which an aromatic polyester capable of forming an anisotropic melt phase is discharged from a nozzle having pores having a diameter of 0.1 mm or less, spun and wound up, under the following conditions: Melting point of polyester +20
The melt viscosity at a shear rate of 1000 sec ^{-1 at} 50 ° C is 50.
Use a polymer of less than 0 poise, and set the shear rate when passing through the nozzle to 10 ³ to 10 ⁹ (sec ⁻¹ ).
The discharge linear velocity in the nozzle is 5 m / min or more and 40 m / min or less, the winding speed is 150 m / min or more and 8000 m / min or less, and the ratio of the winding speed to the discharge linear velocity is 20 or more, the spinneret temperature is set to the melting point of the polyester + 15 ° C. or more, and the temperature of the fiber at a point 30 cm away from the nozzle surface after discharge is set to the melting point of the polyester −150 ° C. or less. A method for producing ultrafine fibers of melt-anisotropic aromatic polyester, which is characterized by being used.