KR101466281B1 - Process for preparing polymer yarn containing conductive copper compound - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a method for producing conductive copper fine particles and a polymer yarn containing the copper fine particles. The present invention relates to a method for producing conductive copper fine particles and a method for manufacturing the conductive copper fine particles by mixing and fusing copper fine particles with a polymer to produce a yarn to secure oxidation stability in the air, And provides electrostatic removing function while imparting properties such as antibacterial, deodorant, deodorant, antiviral and anti-fungal properties, and is capable of sustaining semi-permanent performance of functionally added yarn and maintaining sustainable use of conductive copper fine particles The present invention also provides a method for producing a conductive copper microparticle, which comprises the steps of simultaneously conducting oxidation and reduction reactions on an aqueous copper salt solution to form conductive fine copper particles ; Compounding copper microparticles into at least one selected from among polypropylene, polyester, nylon and polyethylene, followed by drying / crystallizing and masterbatching; Preparing a polymer yarn with a masterbatch into which copper microparticles have been introduced, the method comprising: And a control unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a process for preparing a synthetic fiber containing conductive copper microparticles,

The present invention relates to a method for producing synthetic fibers comprising conductive copper fine particles and a yarn produced by the method. More particularly, the present invention relates to a method for producing synthetic fibers comprising conductive copper fine particles, and more particularly to a yarn having oxidation stability and thermal stability in air, A method for producing synthetic fibers including conductive copper fine particles capable of securing moldability, and a yarn produced by the method.

Generally, Synthetic Fiber (Synthetic Fiber) refers to synthetic polymer fibers, and refers to fibers made from synthetic polymers polymerized by chemical methods.

Such synthetic fibers are usually made of an insulator having a high electrical resistance, so that a large amount of static electricity is generated during use and an electrostatic discharge is caused.

As a result, static electricity generated from synthetic fibers is considered to be inevitable. However, due to the development of fiber and polymer engineering, the electric conductivity of fibers made of an organic polymer, which is an insulator, is raised to a certain level, It has opened up the possibility of reducing the problem, but it is still not at the level of mass production or economic efficiency.

On the other hand, in the case of the fibers through which electricity passes through the synthetic fibers, the fibers can be divided into a conductive fiber (antistatic fiber) and a conductive fiber (or a conductive fiber) depending on the level of the conductivity. The conductive fiber is a fiber having a function of discharging the generated static electricity to the outside so that static electricity is not generated, and the conductive fiber is a fiber having a function of electricity such as a conductor.

The method for producing the conductive fibers and the conductive fibers as described above is a production method for imparting discharge and conductive functions by injecting a conductive material or a conductive material into the fibers and a method for post- And a manufacturing method of imparting a discharge and a conductive function.

Here, in the manufacturing method of the conductive fiber and the conductive fiber, a conductive material such as metal is coated on the surface of the fiber to impart conductivity to the fiber. The conductive material may be a metal such as a vacuum deposition method, a sputtering method, Is attached to the surface of the fiber. On the other hand, electroplating plating is used although less sophisticated.

The fibers produced in this manner are unsuitable for garments because they are rough and have a metallic appearance and are mainly used for industrial or nonwoven fabrics.

On the other hand, in the manufacturing method of the conductive fiber and the conductive fiber, the manufacturing method of injecting the conductive or dielectric material into the fiber is a method of putting into the fiber in the process of spinning the conductive material, to be.

Carbon black, Mica, talc, or the like is used as the conductive material, and the conductivity of the fiber is influenced not only by the kind and amount of the conductive material but also by the shape thereof.

At this time, since the conductive and dielectric fibers including carbon black have a black color, they are limited in their application, so that the conductive material is not apparently exposed using a complex spinning method, and a metal such as silver or copper Metal oxides may also be used.

However, copper and aluminum are easily oxidized by contact with air due to the contact of fine particles with the air, and thus the conductivity is lost in a short period of time. Silver (Ag) is excellent in conductivity and high in preference, Which is too expensive to apply in practice.

On the other hand, in recent years, in addition to the function of removing static electricity, the hygienic and healthful products have diversified the needs of consumers, and pursue the cleanliness and comfort of the daily living environment.

Namely, when a textile product is worn, metabolic waste discharged through human skin such as sweat, sebum, and sebum attaches to the surface of the fiber, contamination of clothing becomes unsanitary, and in a textile product such as a cloth with contamination, Microorganisms existing on the skin or microorganisms adhered to the outer surface of the skin are likely to be contaminated with human waste substances adhered to the fibers and organic compounds such as pollutants and the like Is decomposed by digestion to generate volatile odor substances. Therefore, the fiber product is produced by antibacterial deodorization to prevent the growth of microorganisms on the fiber product and to prevent the generation of odor.

In addition, there is a growing demand for deodorizing processes for adsorbing odorous components by physicochemical and biometic methods, or decomposing and smelling them.

However, as the demands of such consumers have diversified, technologies for removing static electricity from the fibers and imparting antibacterial, deodorizing, deodorizing and antibacterial functions have been proposed, but they have not been commercialized due to their lack of functions or economical efficiency .

On the other hand, in the method of mixing the antimicrobial agent in the fiber, the antimicrobial agent is mixed into the fiber and polymerized. After completion of the polymerization, the fiber is mixed in the basic polymer just before spinning and mixed in the spinning solution.

Here, in the melt spinning, an antimicrobial agent (inorganic compound) generally having high heat resistance is used so as not to cause thermal decomposition, and a master chip having a high treatment concentration is injected and mixed just before spinning and detaching.

On the other hand, the antimicrobial agent used for the wet spinning is an inorganic compound (such as a metal fine particle or a metal ion containing zeolite) or an organic compound.

A representative processing method for them is a method of spinning a spinning solution mixed with a polymer raw material and an antimicrobial agent in an organic solvent to increase heat treatment. In the above-described processing method, silver (Ag) and The same component is ionically bound and incorporated into melt-spinnable polyester or nylon polymer to contain an antimicrobial agent in the fiber.

Disclosure of the Invention The present invention has been conceived to solve the problems as described above, and it is an object of the present invention to provide a method for producing a yarn by mixing and spinning copper fine particles with a polymer to secure oxidation stability in the air and to secure heat resistance The present invention relates to a method for producing conductive copper microparticles which can provide antistatic self-eliminating function while securing antibacterial, deodorizing, deodorizing, antiviral and antifungal properties, And to provide a polymeric yarn and a nonwoven fabric containing the same.

The present invention also provides a method for producing a copper foil, which is capable of imparting an electrostatic removing function to a warrior, a worsted yarn, a woolen yarn, a woolen yarn, a nonwoven fabric and the like, And to provide a polymer yarn and a nonwoven fabric containing the same.

In order to accomplish the above object, the present invention provides a method for producing synthetic fibers comprising conductive copper microparticles, comprising the steps of simultaneously performing an oxidation and reduction reaction on an aqueous solution of copper salt (copper salt) Producing fine particles; Compounding the copper microparticles into one or more selected from among polypropylene, polyester, nylon and polyethylene, followed by drying / crystallizing and masterbatching; And producing the polymer yarn by spinning or mixing the polymer yarn with the master batch containing the copper microparticles.

Here, the aqueous solution of the copper salt is at least one selected from among copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ) and copper chloride (CuCl ₂ ).

In addition, the aqueous solution of the copper salt may contain at least one selected from the group consisting of sulfamic acid, sodium hypophosphite, sodium borohydride, ethylenediamine tetra-acetic acid (EDTA), palladium chloride, Magnesium, and glyoxylic acid to produce copper microparticles.

At this time, at least one of hydroquinone, hydrazine and formalin is used in place of sodium hypophosphite and sodium borohydride in producing the copper microparticles.

The present invention provides synthetic fibers prepared by the method for producing synthetic fibers and a nonwoven fabric comprising the synthetic fibers.

INDUSTRIAL APPLICABILITY As described above, the present invention having such a constitution as described above is capable of maintaining oxidation stability in the air, ensuring heat resistance capable of enduring melt spinning, having a function of removing static electricity, It is possible to secure deodorant, antiviral and antifungal properties, and to maintain the semi-permanent performance of the functional yarn and to maintain and use it, and to achieve superior economical efficiency compared to conventional antistatic and antibacterial yarns You can.

In addition, the present invention provides antibacterial, deodorant, deodorizing, antiviral, antifungal and antistatic functions when mixed with an antistatic agent, a worsted yarn, a woolen wool and a nonwoven fabric, It can be applied not only to sanitary gloves such as gowns and bandages but also to special purpose clothes such as combat uniforms. It is also applicable to deodorizing and other items such as antibacterial socks, shoes lining, air conditioning filters, air conditioner filters and automobile air filters. It is possible to utilize the antifouling performance and to expand its use to the marine industrial net and the net net.

1 is a flow chart showing a method for producing conductive copper fine particles according to the present invention,

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

1 is a flow chart showing a method for producing conductive synthetic fibers according to the present invention.

As shown in the drawing, the method for producing conductive copper microparticles according to the present invention produces conductive copper microparticles in the form of powder by simultaneously performing oxidation and reduction reactions on an aqueous copper salt solution by a chemical precipitation method.

Herein, the aqueous copper salt solution may be mixed with sulfamic acid, sodium hypophosphite, sodium borohydride, ethylenediamine tetra-acetic acid (EDTA), chloride Copper is reacted with at least one selected from the group consisting of Palladium Chloride, Magnesium, and Glyoxylic Acid to produce copper microparticles.

At this time, the oxidation and reduction ion states of the aqueous copperate solution are reacted with copper metal ions using sulfamic acid as a pH adjusting solution.

That is, to maintain the reaction time so that the copper metal ion of the copper citrate aqueous solution has reactivity, sulfamic acid is added to the pH adjusting solution.

At this time, it is preferable that the pH adjustment liquid is adjusted by adjusting pH to 3 to 4, which is a hydrogen ion index.

Then, electrons are added to the copper metal ions of the copper citrate aqueous solution by using the above sodium hypophosphite and sodium borohydride to reduce them to metal.

That is, when the surface area of the copper metal ion is increased, in order to increase the activity of the surface energy and thereby prevent the increase of the adsorption capacity of oxygen, the sodium hypophosphite, sodium borohydride, An electron is given to the copper metal ion of the aqueous solution and is reduced to a metal, thereby giving a reduction reactivity to the copper metal ion.

In one embodiment of the present invention, the aqueous solution of the copper salt is reacted with a reducing agent such as sulfamic acid, sodium hypophosphite, sodium borohydride, ethylenediamine tetra-acetic acid (EDTA) The present invention relates to a method for producing copper microparticles by reacting at least one selected from the group consisting of Palladium Chloride, Magnesium and Glyoxylic Acid to produce copper microparticles, (Sodium borohydride) instead of sodium hypophosphite and sodium borohydride as long as it is oxidized by the contact with the electrolyte solution and can be prevented from deteriorating in conductivity and antibacterial and deodorizing function as time goes by, It is also possible to use at least one of hydroquinone, hydrazine and formalin.

The ethylenediamine tetraacetic acid (EDTA) is added to make copper microparticles in the form of monodispersed fine particles in the copper metal ion state of the aqueous copperate solution. Ethylene Diamine Tetraacetic acid (Ethylene Diamine Tetra- Acetic acid (EDTA) controls ionic strength and particle charge.

Then, the palladium chloride (Palladium Chloride) is added as a catalyst to increase the yield. That is, a strong positive palladium chloride (Palladium Chloride) is added as a catalyst to improve the yield of copper microparticles.

Magnesium and glyoxylic acid are then added to the copper microparticles to convert them from the active state to the inactive state to prevent the oxides from being deposited.

As described above, when the aqueous solution of the copper salt is reacted with sulfuric acid (Sulfamic Acid), sodium hypophosphite, sodium borohydride, ethylenediamine tetra-acetic acid (EDTA), palladium chloride (Sulfamic Acid), Sodium Hypophosphite, Sodium Borohydride, and Ethylene Glyoxylic Acid), at least one selected from the group consisting of Palladium Chloride, Magnesium, Glyoxylic Acid, (EDTA), palladium chloride, magnesium, and glyoxylic acid are successively reacted with an aqueous copper salt solution to prepare copper fine powder having oxidation stability in air Copper microparticles are obtained.

The precipitated copper microparticles are washed and dried to obtain copper microparticles in the form of spherical powder having an average diameter of 0.5 to 10.

Here, the at least one salt selected from the group consisting of copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ) and copper chloride (CuCl ₂ ) is used as the aqueous copper salt solution.

The copper microparticles are compounded into at least one selected from among polypropylene, polyester, nylon and polyethylene, followed by drying / crystallizing and charging the polymer into a polymer to prepare a master batch. The polymer yarn is fed into the master batch It is manufactured by spinning or spinning. The content of copper fine particles relative to the total weight of yarn during spinning is preferably 1 to 10% by weight. When the content of the copper fine particles is less than 1% by weight, the antibacterial property and the deodorant property are deteriorated. When the content is more than 10% by weight, the formability and economical efficiency are deteriorated. The content of copper fine particles relative to the total weight of the yarn in the sheath region in the case of the radiation in the form of Cisco is preferably 1 to 20% by weight. When the content of the copper fine particles is less than 1% by weight, the antibacterial property and the deodorant property are deteriorated. When the content is more than 20% by weight, the formability and economical efficiency are lowered.

At this time, the masterbatch of the copper microparticles and the polymer is prepared at a temperature ranging from 150 to 360 ° C.

As described above, the copper microparticles obtained by conducting the oxidation and reduction reaction simultaneously by the chemical precipitation method of the aqueous copper salt solution are melt-mixed into a polymer composed of polyester, nylon, polyethylene and polyurethane resin, It has antistatic properties due to electrical resistivity of 10 ¹⁰ Ω · ㎝ or less, and can also achieve antibacterial, deodorizing, deodorizing, antiviral and antifungal properties due to the action of copper ions.

Hereinafter, the process for producing conductive copper microparticles according to the present invention will be described.

First, an aqueous copper salt solution for carrying out the oxidation and reduction reaction is introduced into the reactor.

Then, after the reactants are charged into the reaction vessel, the temperature is raised to a temperature of about 60 to 80, and the temperature is maintained.

Preferably, the temperature of the reaction vessel is maintained after the temperature of the reaction vessel has been increased to 70 after the addition of the reactants.

As described above, each reaction product is charged into the reaction tank, and after the temperature is raised, the reaction is carried out for about 100 minutes while stirring at about 150 to 250 RPM.

In an embodiment of the present invention, each reaction product charged into the reaction tank is reacted for about 100 minutes while stirring at 150 to 250 RPM. However, each reaction product introduced into the reaction tank is reacted for about 100 minutes with stirring at 200 RPM .

Then, it is cooled at low speed for approximately 20 minutes, rinsed to approximately pH 7, centrifugally dehydrated, and dried in an oven of approximately 150 to obtain copper microparticles in powder form.

Hereinafter, preferred embodiments of the conductive copper fine particle manufacturing method according to the present invention will be described. It is to be understood, however, that the present invention is not limited thereto. Antimicrobial, deodorant, deodorization, antiviral and antifungal yarn production of the polymer yarn containing the conductive copper fine particles prepared in the examples of the present invention were evaluated in the following manner.

- Antistatic (conductive)

The line resistance (Ω · cm) of the yarn was measured under conditions of a temperature of 23 ° C., a relative humidity of 60%, and an applied voltage of 500 V, and the conductivity was determined by the line resistance of the film, and an insulation resistance meter (HIOKI-3288, .

- Friction Voltage

Friction Voltage (Method B), Volt

Test conditions - Temperature: 20 ± 2 ℃

Relative humidity: 40 ± 2 ℃ RH

Friction foil: Cotton and blankets specified in KS K 0905

- Antimicrobial activity

Strain used: Staphylococcus aureus (ATCC 6538)

            Pneumococcus Klebsiella pneumoniae (ATCC 4352)

Use nonionic surfactant: TWEEN 80 (0.05%)

Growth value: Growth value of control (valid when Mb / Ma = 31.6 or higher)

Bacteriostatic reduction value (S): log Mb - log Mc (difference in the number of viable cells of the processed sample relative to the unprocessed sample)

Bacterial reduction rate (%): (Mb-Mc) x 100 / Mb

           Ma: Number of living bacteria immediately after inoculation of control flap

           Mb: Number of viable cells after 18 hours incubation of control pieces

Mc: Number of viable cells after 18 hours of sample culture

- Deodorizing test conditions

Japan Textile Evaluation Technology Test Method (JTETC): A 10 cm × 10 cm test sample is placed in a 5 L tetra bag, and 3 L of the gas adjusted to the initial concentration is injected. After 2 hours, the gas concentration is measured with a detection tube Detector tube: Ammonia 3La)

Example 1

At about room temperature, 50 g of copper nitrate (Cu (NO ₃ ) ₂ ) crystal powder is dissolved in 200 g of distilled water to obtain a copper nitrate aqueous solution.

Then, 25 g of Sulfamic Acid, Sodium Hypophosphite, 0.3 g of Sodium Borohydride, 0.1 g of Ethylene Diamine Tetra-Acetic Acid (EDTA) was added to the reaction tank, ), 5 cc of Palladium Chloride, 1 g of Magnesium and 0.5 g of Glyoxylic Acid.

At this time, the temperature of the reactor is raised to 70, and the temperature is maintained at an elevated temperature, and the reaction time is 100 minutes while stirring at 200 RPM.

Thereafter, it is warmed for 20 minutes, rinsed to a pH of 7, centrifugally dehydrated and then dried in an oven at 150 to obtain copper microparticles in powder form.

Subsequently, the copper microparticles and the polypropylene obtained by the above-described production method were prepared in a 20:80 weight ratio using a twin screw mixer. A yarn in the form of a sheath core is produced using the mast batch prepared above. At this time, the sheath region of the yarn is made of a polypropylene yarn containing 10% by weight of copper fine particles, and the core region is made of 100% polypropylene containing 0% by weight of copper fine particles.

Example 2

At about room temperature, 50 g of copper nitrate (Cu (NO ₃ ) ₂ ) crystal powder is dissolved in 200 g of distilled water to obtain a copper nitrate aqueous solution.

Then, 25 g of Sulfamic Acid, Sodium Hypophosphite, 0.3 g of Sodium Borohydride, 0.1 g of Ethylene Diamine Tetra-Acetic Acid (EDTA) was added to the reaction tank, ), 5 cc of Palladium Chloride, 1 g of Magnesium and 0.5 g of Glyoxylic Acid.

At this time, the temperature of the reactor is raised to 70, and the temperature is maintained at an elevated temperature, and the reaction time is 100 minutes while stirring at 200 RPM.

Thereafter, it is warmed for 20 minutes, rinsed to a pH of 7, centrifugally dehydrated and then dried in an oven at 150 to obtain copper microparticles in powder form.

Subsequently, the copper microparticles and the polypropylene obtained by the above-described production method were prepared in a 20:80 weight ratio using a twin screw mixer. A yarn in the form of a sheath core is produced using the mast batch prepared above. At this time, the sheath region of the yarn is made of a polypropylene yarn containing 7% by weight of copper fine particles, and the core region is made of 100% polypropylene containing 0% by weight of copper fine particles.

Example 3

At about room temperature, 50 g of copper nitrate (Cu (NO ₃ ) ₂ ) crystal powder is dissolved in 200 g of distilled water to obtain a copper nitrate aqueous solution.

Then, 25 g of Sulfamic Acid, Sodium Hypophosphite, 0.3 g of Sodium Borohydride, 0.1 g of Ethylene Diamine Tetra-Acetic Acid (EDTA) was added to the reaction tank, ), 5 cc of Palladium Chloride, 1 g of Magnesium and 0.5 g of Glyoxylic Acid.

At this time, the temperature of the reactor is raised to 70, and the temperature is maintained at an elevated temperature, and the reaction time is 100 minutes while stirring at 200 RPM.

Thereafter, it is warmed for 20 minutes, rinsed to a pH of 7, centrifugally dehydrated and then dried in an oven at 150 to obtain copper microparticles in powder form.

Subsequently, the copper microparticles and the polypropylene obtained by the above-described production method were prepared in a 20:80 weight ratio using a twin screw mixer. A yarn in the form of a sheath core is produced using the mast batch prepared above. At this time, the sheath region of the yarn is made of a polypropylene yarn containing 5% by weight of copper fine particles, and the core region is made of 100% polypropylene containing 0% by weight of copper fine particles.

Example 4

50 g of copper sulfate (CuSO ₄ ) crystal powder is dissolved in 200 g of distilled water at a room temperature of about 25 to obtain an aqueous solution of copper sulfate.

Then, 25 g of Sulfamic Acid, Sodium Hypophosphite, 0.3 g of Sodium Borohydride, Ethylene Diamine Tetra-Acetic Acid (EDTA) was added to the reaction tank, 5 g of palladium chloride, 1 g of magnesium, and 0.5 g of glyoxylic acid are put into the reactor.

At this time, the temperature of the reactor is raised to 70, and the temperature is maintained at an elevated temperature, and the reaction time is 100 minutes while stirring at 200 RPM.

Thereafter, it is warmed for 20 minutes, rinsed to a pH of 7, centrifugally dehydrated and then dried in an oven at 150 to obtain copper microparticles in powder form.

Subsequently, the copper microparticles and the polypropylene obtained by the above-described production method were prepared in a 20:80 weight ratio using a twin screw mixer.

Mixed in polypropylene in the form of a master batch, and then spun to produce a polypropylene yarn containing 5% by weight of conductive copper fine particles.

Comparative Example 1

Thereby producing a polypropylene yarn containing 0 wt% of the conductive copper fine particle production.

Friction Voltage (v) Antibacterial (Bacterial reduction rate:%) Deodorant (Ammonia:%) Example 1 380 99.9 99.9 Example 2 430 99.9 99.4 Example 3 520 99.7 98.4 Example 4 600 99.1 97.9 Comparative Example 1 6000  12.0 14.0

As shown in the above Table 1, the polymer source having the copper microparticles prepared therefrom and containing the copper microparticles is capable of removing antibacterial, deodorizing, deodorizing, antiviral, antifungal and static electricity, It can be applied not only to hygienic areas such as gowns and bandages, but also to special purpose clothing such as combat uniforms. It can be applied to deodorizing and antibacterial socks, shoe linings, antibacterial / deodorizing filters for air conditioning, antibacterial / It can be applied to other equipment such as air filter / deodorant filter and also it can be extended to the marine industry net and net net net by utilizing antifouling performance.

Although the present invention has been shown and described with respect to specific embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. Anyone will know easily.

Claims (5)

A method for producing a synthetic fiber including conductive fine copper particles,
Oxidation and reduction reactions are simultaneously carried out on an aqueous solution of copper ( _II ) salt consisting of at least one selected from copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ) and copper chloride Preparing conductive fine copper particles in powder form;
Compounding the copper microparticles into one or more selected from among polypropylene, polyester, nylon and polyethylene, followed by drying / crystallizing and masterbatching; And
Preparing a yarn by spinning with a master batch in which the copper microparticles are injected,
Wherein the yarn produced by spinning or cocoon spinning in a master batch has a friction voltage of 380 to 600 V, an antibacterial value of 99.1 to 99.9%, a deodorization of 97.9 to 99.9% The content of copper fine particles relative to the total weight of yarn in the cis region is in the range of 1 to 10% by weight, 20% by weight based on the total weight of the synthetic fibers. delete The method according to claim 1,
The aqueous solution of the copper salt may be mixed with an aqueous solution of a sulfamic acid, sodium hypophosphite, sodium borohydride, ethylenediamine tetra-acetic acid (EDTA), palladium chloride, magnesium Wherein the copper microparticles are produced by reacting at least one selected from the group consisting of magnesium, magnesium and glyoxylic acid. The method according to claim 1,
The aqueous solution of the copper salt is mixed with one or two selected from among sulfamic acid, ethylenediamine tetra-acetic acid (EDTA), palladium chloride, magnesium, and glyoxylic acid. Wherein at least one selected from the group consisting of hydroquinone, hydrazine and formalin is used in the production of the copper microparticles by reacting the copper microparticles with one or more species selected from the group consisting of Gt; A nonwoven fabric comprising the synthetic fibers produced by the method for producing synthetic fibers according to any one of claims 1, 3 and 4.

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