JP2022137820A - Conductive, heat-resistant and highly tough fiber, and method for producing the same - Google Patents

Abstract

To provide a conductive, heat-resistant and highly tough fiber which has strength and elongation capable of being suitably used for applications requiring flexibility such as protective clothing use while having high heat resistance and which is highly electroconductive.SOLUTION: The conductive, heat-resistant and highly tough fiber has an electric resistivity of 103 Ω cm or less, a breaking strength of 3.5 to 10 cN/dtex, a breaking elongation of 10 to 30%, and a melting point of 290°C or higher.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a conductive heat-resistant high-toughness fiber and a method for producing the same. More specifically, the present invention relates to a conductive heat-resistant high-toughness fiber characterized by an excellent balance of strength, elongation, heat resistance, and conductive physical properties, and a method for producing the same.

In recent years, with the development of spinning technology, various fibers have been industrialized, and by selecting the chemical structure and spinning conditions that make up the fiber, fibers with physical properties according to the required performance and use are developed and manufactured.

In addition to the effect of imparting conductivity depending on the method of use, fibers having conductivity can also be suitably used when imparting static elimination performance. Because of these properties, conductive fibers are mainly used as general-purpose fibers and applied to clothing and industrial applications, and are still one of the most important functional fibers today. Various manufacturing methods of conductive fibers have been disclosed, for example, the fiber surface is plated with a metal to impart conductivity, and the raw material polymer is filled with conductive particles and spun to provide conductivity. There is a way to give

On the other hand, heat resistance is one of the performances required in material development. For example, fibers made of wholly aromatic polyamide (sometimes referred to as aramid fibers) are particularly useful as high-strength, heat-resistant, and flame-retardant fibers. Conductive fibers that have been widely used so far are nylon and acrylic fibers, which may not be suitable for applications that require heat resistance. However, if electrical conductivity can be imparted to heat-resistant fibers such as wholly aromatic polyamides, the range of applications can be expected to expand.

Attempts to impart conductivity to such wholly aromatic polyamide fibers have been disclosed so far. For example, in JP-A-2-216264 (Patent Document 1) and JP-A-2006-2213 (Patent Document 2), conductivity is imparted by a method of coating copper sulfide or silver on the surface of aramid fibers. ing. Japanese Patent Application Laid-Open No. 2006-342471 (Patent Document 3) discloses a method of obtaining a conductive para-aramid fiber by adding carbon nanotubes and conductive fine particles other than carbon nanotubes to a spinning solution and spinning. .

However, the method of coating the fiber surface to impart conductivity requires surface treatment, which poses a problem in terms of productivity, and in terms of quality, there is a problem in durability due to wear and the like.

In addition, in the method of adding and mixing conductive fine particles in a resin and spinning, the conductive fine particles are held inside the fiber, so the durability of the conductivity is relatively high, but it leads to the deterioration of the mechanical properties of the fiber. Sufficient strength could not be obtained.
Therefore, there has been a demand for a well-balanced fiber that maintains high heat resistance and high physical properties while having conductivity.

JP-A-2-216264 Japanese Unexamined Patent Application Publication No. 2006-2213 Japanese Patent Application Laid-Open No. 2006-342471

An object of the present invention is to provide a conductive heat-resistant high-toughness fiber having high heat resistance, strength and elongation, and high electrical conductivity, as described above. .

As a result of intensive studies to solve the above problems, the present inventors have found that by imparting conductive fine particles to a polymer obtained by copolymerizing a plurality of specific monomers in a specific ratio to form a fiber, a high The inventors have found that it is possible to obtain a conductive heat-resistant and high-toughness fiber having a balance of heat resistance, strength and elongation and high electrical conductivity, and have completed the present invention.

That is, according to the present invention,
1. A conductive heat-resistant high-toughness fiber characterized by having an electrical resistivity of 10 ³ Ωcm or less, a breaking strength of 3.5 to 10 cN/dtex, a breaking elongation of 10 to 30%, and a melting point of 290° C. or higher;
2. 1. The conductive heat-resistant high-toughness fiber according to 1 above, which contains 6 to 40% by mass of conductive fine particles in the fiber;
3. 2. The conductive heat-resistant high-toughness fiber according to 2 above, wherein the conductive fine particles are conductive carbon black;
4. A copolymer aramid polymer in which the conductive heat-resistant high-toughness fibers are composed of a structure containing metaphenylene terephthalamide units and/or metaphenylene isophthalamide units and paraphenylene terephthalamide units and/or paraphenylene isophthalamide units. 4. The conductive heat-resistant high-toughness fiber according to any one of 1 to 3 above, which is composed of coalescence; The conductive heat-resistant high-toughness fiber contains at least three structures selected from the group of meta-phenylenediamine, para-phenylenediamine, isophthaloyl, and terephthaloyl, meta-phenylenediamine and/or isophthaloyl monomer units, para-phenylenediamine and / or the conductive wholly aromatic polyamide fiber according to any one of the above 1 to 4, wherein the molar ratio of terephthaloyl monomer units is in the range of 50 or more and less than 70:50 or less and more than 30;
6. A method for producing a conductive heat-resistant high-toughness fiber, comprising:
A structure containing a meta-phenylene terephthalamide unit and/or a meta-phenylene isophthalamide unit and a para-phenylene terephthalamide unit and/or a para-phenylene isophthalamide unit, wherein the amide units are meta-phenylenediamine and para-phenylene Containing at least three structures selected from the group of diamine, isophthaloyl, and terephthaloyl, the molar ratio of meta-phenylenediamine and/or isophthaloyl monomer units to para-phenylenediamine and/or terephthaloyl monomer units is 50 or more and less than 70: Using a copolymerized aramid polymer having a weight average molecular weight in the range of 50 or less and greater than 30 and having a weight average molecular weight of 400,000 to 1,000,000, the following steps (1) to (5) are performed, and the manufacturing conditions of (6) A method for manufacturing a conductive heat-resistant high-toughness fiber that satisfies
(1). The copolymerized aramid polymer is dissolved in an amide solvent in the range of 10 to 30% by mass, and the conductive fine particles are dispersed in the copolymerized aramid polymer at 6 to 40% by mass to prepare a dope for spinning, and a spinneret. through,
(2). coagulated by spinning in an aqueous coagulation bath containing 1 to 20% by mass of an amide solvent;
(3). (4) washing with water in an aqueous washing bath, followed by drawing in a boiling water drawing bath in a range of 1.1 to 5.0 times; Perform dry heat treatment in the range of 100 to 250 ° C,
(5). While applying heat treatment in the range of 290 to 380 ° C., hot drawing is performed at a draw ratio of 2.0 to 10.0 times,
(6). The total draw ratio of the boiling water draw ratio and the hot draw ratio is 5 times or more.

The conductive heat-resistant high-toughness fiber obtained by the present invention has heat resistance that can withstand a use environment of 250 ° C. or higher, and has physical properties such as a breaking strength of 3.5 to 10 cN / dtex and an elongation of 10 to 30%. While having an electrical resistivity of 10 ³ Ωcm or less, it exhibits unprecedentedly high conductivity, so it is suitable for use in protective clothing applications that require strength, flexibility, and high electrostaticity, for example. be able to.

The present invention will be described in detail below.
The conductive heat-resistant high-toughness fiber of the present invention has an electrical resistivity of 10 ³ Ωcm or less, a breaking strength of 3.5 to 10 cN/dtex, a breaking elongation of 10 to 30%, and a melting point of 290° C. or higher. Characterized by

Polymers constituting such conductive heat-resistant and high-toughness fibers include wholly aromatic polyamides (hereinafter sometimes referred to as aramids), specifically composed of an aromatic diamine component and an aromatic dicarboxylic acid component. The aromatic diamine component and the aromatic dicarboxylic acid component each have at least one of meta-type and para-type structures, and are synthesized by copolymerization of these.

In the conductive heat-resistant high-toughness fiber of the present invention, preferably used are metaphenylene terephthalamide units and/or metaphenylene isophthalamide units and paraphenylene terephthalamide from the viewpoint of mechanical properties, heat resistance, and flame retardancy. It is a wholly aromatic polyamide comprising a copolymerized aramid polymer composed of a structure containing amide units and/or paraphenyleneisophthalamide units.

In the conductive heat-resistant high-toughness fiber of the present invention, preferably, a wholly aromatic polyamide is randomly copolymerized and contains at least three structures selected from the group of metaphenylenediamine, paraphenylenediamine, isophthaloyl, and terephthaloyl. , the mol% of meta-phenylenediamine and/or isophthaloyl monomer units is 50 or more and less than 70, and the mol% of paraphenylenediamine and/or terephthaloyl monomer units is 50 or less and more than 30. More preferably, the mol% of meta-phenylenediamine and/or isophthaloyl monomer units is 50 or more and less than 67 mol%, and the mol% of paraphenylenediamine and/or terephthaloyl monomer units is 50 or less and more than 33 mol% of the whole. If the mol% of metaphenylenediamine and/or isophthaloyl monomer units is 70 or more, the desired strength cannot be achieved. Further, when the mol % of meta-phenylenediamine and/or isophthaloyl monomer units is less than 50, the resulting polymer cannot be spun because it does not dissolve in the amide solvent described later. Table 1 below shows combinations of meta-phenylenediamine, para-phenylenediamine, isophthaloyl and terephthaloyl. The present invention preferably includes at least three structures, such as those shown in Examples 1-4, and particularly preferably four structures, such as Example 5.

Examples of the aromatic diamine component as a raw material for the wholly aromatic polyamide include meta-phenylenediamine, para-phenylenediamine, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, etc., and halogens in the aromatic rings thereof. Derivatives having a substituent such as an alkyl group having 1 to 3 carbon atoms can be exemplified.

Examples of raw materials for the aromatic dicarboxylic acid component constituting the wholly aromatic polyamide of the present invention include aromatic dicarboxylic acid halides. Examples of meta-type aromatic dicarboxylic acid halides include isophthaloyl monomers such as isophthaloyl chloride and isophthaloyl bromide, and substituents such as halogens and alkoxy groups having 1 to 3 carbon atoms on the aromatic rings thereof. can be exemplified. Similarly, para-type aromatic dicarboxylic acid halides include terephthaloyl chloride, which is a terephthaloyl monomer, terephthaloyl halides such as terephthaloyl bromide, and halogens, alkoxy groups having 1 to 3 carbon atoms, etc. on the aromatic rings thereof. can be exemplified as a derivative having a substituent of

As a polymerization method for the wholly aromatic polyamide that can be suitably used for the conductive heat-resistant high-toughness fiber of the present invention, an organic solvent system (eg, tetrahydrofuran) which is not a good solvent for the resulting polyamide containing metaphenylenediamine and isophthalic chloride is used. ) with an aqueous solution system containing an inorganic acid acceptor and a soluble neutral salt (interfacial polymerization, JP-B-47-10863) to isolate a powder of polymetaphenylene isophthalamide polymer; Alternatively, the above diamine and acid chloride are solution-polymerized in an amide solvent, and then neutralized with calcium hydroxide, calcium oxide, etc. (solution polymerization, JP-A-8-074121, JP-A-10-88421). method, but is not limited thereto.

The weight-average molecular weight of the copolymer aramid polymer (also referred to as a wholly aromatic polyamide copolymer) suitably used for the conductive heat-resistant high-toughness fiber of the present invention forms a fiber having a breaking strength that can withstand practical use. From the point of view that it is possible, it is necessary to be 400,000 to 1,000,000 according to the analysis method described later. If the weight-average molecular weight is less than 400,000, not only is the strength at break remarkably reduced, but also stable spinning cannot be carried out. Further, when the molecular weight exceeds 1,000,000, the viscosity becomes too high when preparing and spinning a wholly aromatic polyamide solution, which will be described later, making it difficult to handle and requiring dedicated equipment.

A mixture of a low-molecular-weight polymer and a high-molecular-weight polymer can be used as the polymer within the molecular weight range defined above, and the total molecular weight is defined by adjusting the mixing ratio. For example, when a polymer having a weight average molecular weight of 200,000 and a polymer having a weight average molecular weight of 800,000 are mixed, and the weight average molecular weight of the mixed polymer is 600,000, there is no problem in using the molecular weight range defined in the present invention. do not have.

The conductive heat-resistant high-toughness fiber of the present invention preferably contains 6 to 40% by mass of conductive fine particles in order to obtain electrical resistivity characteristics.
The electrically conductive, heat-resistant, high-toughness fiber of the present invention is produced by using the wholly aromatic polyamide and the electrically conductive fine particles obtained by the above-described production method, and performing the following steps of preparing a spinning solution, spinning and solidifying, washing, and boiling water. It is manufactured through a drawing process, a dry heat treatment process, and a hot drawing process.

[Spinning solution preparation step]
In the spinning solution preparation step, for example, a wholly aromatic polyamide and conductive fine particles are dissolved and dispersed in a solvent to prepare a spinning solution (dope). In preparing the spinning solution, an amide-based solvent is usually used, and examples thereof include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). Among these, it is preferable to use NMP or DMAc from the viewpoint of solubility and handling safety.

As the concentration of the wholly aromatic polyamide in the spinning solution, an appropriate concentration may be appropriately selected from the viewpoint of the coagulation rate and polymer solubility in the subsequent spinning/coagulation step, and is usually 10 to 30. It is necessary to make it into the range of mass %. In order to achieve stable spinning, the range of 15 to 25% by mass is more preferable.

The concentration of the conductive fine particles is preferably 6 to 40% by mass, more preferably 10 to 35%, even more preferably 20 to 30% by mass, based on the wholly aromatic polyamide constituting the fiber. If the concentration of the conductive fine particles is less than 6% by mass, the desired conductivity cannot be exhibited, and if it exceeds 40% by mass, the desired strength cannot be obtained. Here, the conductive fine particles are metal fine particles, metal oxides, carbon black (also referred to as conductive carbon black), and the like, which themselves exhibit conductive performance, unless they inhibit fiber formation. Although not particularly limited, conductive carbon black is preferred in the present invention from the standpoint of manufacturing technology.

The conductive carbon black preferably has a surface specific resistance of 10 to 10 ⁸ Ω, more preferably 10 ² to 10 ⁶ Ω, and more preferably 10 ³ to 10 Ω when measured at a temperature of 20°C and a humidity of 65%. 10 ⁵ Ω is more preferred. If the surface resistivity of the conductive carbon black is within the above range, it is preferable for obtaining a conductive heat-resistant high-toughness fiber having electrical resistivity, which is the object of the present invention.

The surface specific resistance (Ω) of the conductive carbon black is obtained by adding 25% of the conductive carbon black to the polymer solution obtained in Example 1 below, and applying it on the glass cloth with a 3 ml applicator. After that, it is washed with water and dried, and heat-treated in an electric furnace at 330° C. for 2 minutes to obtain a test piece, and the surface specific resistance is measured with Hiresta UP (manufactured by Mitsubishi Chemical Co., Ltd.).

In addition, the particle size of the conductive carbon black is not particularly problematic as long as it is sufficiently small relative to the cross section of the fiber, but the particle size is preferably in the range of 5 to 500 nm, more preferably in the range of 10 to 50 nm. is more preferred. If the particle size is larger than 500 nm, the fiber strength is lowered, and if the particle size is less than 5 nm, the dispersibility deteriorates due to self-aggregation.

In the present invention, an inorganic salt may be introduced into the dope, preferably 0 to 20% by mass of the inorganic salt relative to the dope, and 0 to 10% by mass of the inorganic salt to obtain stable spinnability. It is more preferable to include

Here, if the inorganic salt content exceeds 20% by mass, the coagulation rate becomes too fast and a large number of voids are formed in the fiber, making it impossible to obtain a fiber having the desired physical properties. As inorganic salts, chloride salts such as calcium chloride, magnesium chloride and lithium chloride are preferably used.

[Spinning/coagulation process]
In the spinning/coagulating step, the dope obtained above is spun into a coagulating liquid and coagulated. The spinning device is not particularly limited, and a conventionally known wet spinning device can be used. The number of spinning holes in the spinneret, the diameter of the spinning holes, the state of arrangement, etc. of the spinneret are not particularly limited as long as they can be stably wet-spun. A 0.2 mm multi-hole spinneret or the like can be used.

The temperature of the dope during spinning from the spinneret is preferably 20 to 90°C, more preferably 70 to 90°C.
The coagulation bath used to obtain the fiber of the present invention is an aqueous solution containing 1 to 20% by mass, preferably 3 to 15% by mass, of an amide solvent. The temperature of this aqueous solution is 50
A range of ~90°C is preferred.

In addition, the coagulation bath can contain an inorganic salt such as calcium chloride or magnesium chloride in an amount of preferably 30% by mass or more, more preferably 35 to 45% by mass.
As described above, the dope is spun from a spinneret into a coagulation liquid and passed through a coagulation bath to obtain a coagulation thread.

[Washing process, boiling water stretching process]
The coagulated yarn thus obtained is thoroughly washed in an aqueous washing bath and sent to a boiling water drawing step.
The draw ratio in the boiling water drawing bath should be in the range of 1.1 to 5.0 times, more preferably in the range of 1.1 to 3.0 times. The strength of the finally obtained fiber can be ensured by performing the drawing within the range of the draw ratio and increasing the molecular chain orientation.

[Dry heat treatment process]
A dry heat treatment step is performed on the fibers that have undergone the washing and drawing steps. In the dry heat treatment step, the fibers that have been washed in the above washing step are subjected to a dry heat treatment at 100 to 250°C. Dry heat treatment is preferably carried out in the range of 100 to 200°C. Moreover, it is preferable to carry out the dry heat treatment under a constant length. The temperature of the dry heat treatment mentioned above refers to the set temperature of fiber heating means such as a hot plate and a heating roller.

[Hot drawing process]
In the present invention, the fiber subjected to the dry heat treatment is subjected to a hot drawing process. In the hot-stretching step, stretching is performed while heat-treating in the range of 290 to 380°C. The treatment temperature is preferably in the range of 290-350°C. If the temperature is less than 290°C, high-ratio drawing cannot be performed, and if it exceeds 380°C, discoloration or breakage of the fiber may occur. In the hot drawing step, the draw ratio should be in the range of 2.0 to 10.0 times, preferably 3.0 to 10.0 times. The temperature of the hot drawing treatment refers to the set temperature of fiber heating means such as a hot plate and a heating roller.

The total draw ratio of the boiling water draw ratio and the hot draw ratio in the present invention must be 5 times or more. If the total draw ratio is less than 5 times, the target strength and conductivity cannot be obtained. Therefore, it is necessary to appropriately adjust the boiling water draw ratio and the hot draw ratio in consideration of the condition of the process.

The electrical resistivity of the conductive heat-resistant high-toughness fiber obtained by the above method is 10 ³ Ωcm or less, more preferably 700 Ωcm or less, still more preferably 500 Ωcm or less, and most preferably 200 Ωcm or less. The lower the electrical resistivity is, the more preferable it is because sufficient electrostaticity can be obtained.

The breaking strength of the conductive heat-resistant high-toughness fiber of the present invention is 3.5 to 10 cN/dtex, more preferably 4.0 to 10.0 cN/dtex, still more preferably 4.0 to 7.0 cN/dtex. 0 cN/dtex. If the breaking strength is less than 3.5 cN/dtex, the strength is insufficient for applications such as protective clothing aimed at by the present invention. The breaking elongation of the electrically conductive, heat-resistant, high-toughness fiber of the present invention is 10% to 30%, more preferably 10% to 20%. If the elongation at break is less than 10%, the elongation is not sufficient and the flexibility is not sufficiently exhibited. The melting point of the conductive heat-resistant high-toughness fiber of the present invention must be 290° C. or higher, preferably 300° C. or higher. If the melting point is lower than 290°C, the performance as a heat-resistant fiber cannot be exhibited.

The present invention will be described in detail below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples and Comparative Examples. Each physical property value in Examples and Comparative Examples was measured by the following methods.

[Weight average molecular weight Mw]
According to JIS-K-7252, analysis was performed using a high-performance liquid chromatography device equipped with a column for size exclusion chromatography, and dimethylformamide (containing 0.01 mol% lithium chloride) was used as the developing solvent. . As a standard molecular weight sample, a Sigma-Aldrich polystyrene set (peak top molecular weight Mp=400 to 2,000,000) was used.

[Single fiber fineness]
In accordance with JIS-L-1015, measurement was carried out in accordance with the A method of regular fineness, and the apparent fineness was expressed.

[Breaking strength, breaking elongation]
Using a tensile tester (manufactured by Instron, model: 5565), measurements were made under the following conditions according to JIS-L-1015.
(Measurement condition)
Grip interval: 20mm
Initial load: 0.044cN (1/20g/dtex)
Tensile speed: 20mm/min

[Electrical resistivity of fiber]
Using an SM-8210 pole super megohmmeter manufactured by Toa Denpa Kogyo Co., Ltd., the measurement was performed in an atmosphere with a relative humidity of 65 RH%. The sample length of the fiber is 10 cm (L (cm)), a voltage of 0.5 KV is applied to this sample length, the electrical resistivity R (Ω) at that time is measured, and the cross-sectional area of the conductive yarn is S (cm ² ), it was obtained from ρ (Ωcm)=R×(S/L). In the examples and comparative examples of the present invention, S is considered to be a fiber density d = 1.39 g / cm ³ , D is a value obtained by converting the total fineness value (dtex) directly into weight, S = D / (1000000 xd). The number of repeated measurements at this time was 5, and the average value was taken as the electrical resistivity.

[Melting point of fiber]
The melting point of the fiber was determined by thermomechanical analysis according to JIS-K-7197. The melting point was defined as the apex temperature of the peak detected on the high temperature side or the temperature at which peak detection became impossible due to dissolution of the fiber.

[Example 1]
Copolymerized aramid polymer containing 67 mol% of meta-phenylenediamine and isophthaloyl monomer units and 33 mol% of para-phenylenediamine and terephthaloyl monomer units by interfacial polymerization according to JP-B-47-10863. A powder was synthesized. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 2:1. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 2:1. The weight average molecular weight was 660,000. This polymer powder and conductive carbon black particles (surface resistivity is 10 ⁴ Ω) were dissolved and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution. At this time, the mass concentration of the copolymerized aramid polymer was adjusted to 16% relative to the polymer solution, and the conductive carbon black was adjusted to 30% by mass relative to the aramid polymer.

This polymer solution was heated to 85° C. and spun into a coagulation bath at 85° C. through a spinneret having a hole diameter of 0.1 mm and 100 circular ejection holes. The composition of this coagulation bath is 43% by mass of calcium chloride, 4% by mass of NMP, and 53% by mass of the remaining water. After that, it was temporarily pulled out into the air.

The coagulated filaments were washed with water in the first and second water washing baths for a total immersion time of 200 seconds. The first and second aqueous washing bath temperatures used were 20° C. and 30° C., respectively. The washed yarn was stretched 1.4 times in boiling water at 90°C, then immersed in hot water at 90°C for 40 seconds and washed.

Next, after being wound around a roller having a surface temperature of 170° C. and subjected to a dry heat treatment, the fiber was stretched 5.7 times with a hot plate having a surface temperature of 325° C. to obtain a wholly aromatic polyamide fiber.
The obtained fiber had a fineness of 2.0 dtex, a breaking strength of 4.9 cN/dtex, a breaking elongation of 14%, a melting point of 301° C., and an electric resistivity of 61.1 Ωcm.

[Example 2]
Copolymerized aramid polymer powder containing 60 mol % of meta-phenylenediamine and isophthaloyl monomer units and 40 mol % of para-phenylenediamine and terephthaloyl monomer units by interfacial polymerization according to JP-B-47-10863. was synthesized. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 3:2. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 3:2. The weight average molecular weight was 650,000. This polymer powder and conductive carbon black particles (surface resistivity is 10 ⁴ Ω) were dissolved and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution. At this time, the mass concentration of the copolymerized aramid polymer was adjusted to 18% relative to the polymer solution, and the conductive carbon black was adjusted to 25% relative to the aramid polymer.

This polymer solution was heated to 85° C. and spun into a coagulation bath at 88° C. through a spinneret having a circular hole diameter of 0.1 mm and 100 holes as a spinning dope. The composition of this coagulation bath is 44% by mass of calcium chloride, 2% by mass of NMP, and 54% by mass of the remaining water. After that, it was temporarily pulled out into the air.

The coagulated filaments were washed with water in the first and second water washing baths for a total immersion time of 200 seconds. The first and second aqueous washing bath temperatures used were 20° C. and 30° C., respectively. The washed yarn was stretched 2.5 times in boiling water at 90°C, then immersed in hot water at 90°C for 40 seconds and washed. Next, after being wound around a roller with a surface temperature of 170° C. and subjected to a dry heat treatment, it was drawn four times with a hot plate having a surface temperature of 330° C. to obtain a wholly aromatic polyamide fiber.
The resulting fiber had a fineness of 1.7 dtex, a breaking strength of 5.2 cN/dtex, a breaking elongation of 16%, a melting point of 306° C. and an electrical resistivity of 171 Ωcm.

[Comparative Example 1]
Copolymerized aramid polymer powder containing 75 mol% of metaphenylenediamine and isophthaloyl monomer units and 25 mol% of paraphenylenediamine and terephthaloyl monomer units by interfacial polymerization according to JP-B-47-10863. was synthesized. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 3:1. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 3:1. The weight average molecular weight was 700,000. This polymer powder and conductive carbon black particles (surface resistivity is 10 ⁴ Ω) were dissolved and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution. At this time, the mass concentration of the copolymerized aramid polymer was adjusted to 18% relative to the polymer solution, and the conductive carbon black was adjusted to 25% relative to the aramid polymer.

This polymer solution was spun under the conditions of Example 1 to obtain a wholly aromatic polyamide fiber. At this time, the drawing ratio of boiling water was limited to 3.0 times, and the drawing ratio of the hot plate was limited to 1.3 times.
The resulting fiber had a fineness of 1.9 dtex, a breaking strength of 4.9 cN/dtex, a breaking elongation of 17% and a melting point of 340°C. Since the total draw ratio was not sufficiently obtained as described above, the electrical resistivity showed a high value of 7.98×10 ⁶ Ωcm.

[Comparative Example 2]
Copolymerized aramid polymer powder containing 33 mol% of meta-phenylenediamine and isophthaloyl monomer units and 64 mol% of para-phenylenediamine and terephthaloyl monomer units by interfacial polymerization according to JP-B-47-10863. was synthesized. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 1:2. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 1:2. The polymer could not be spun because it did not exhibit good solubility in solvents including NMP.

[Comparative Example 3]
A copolymerized aramid polymer powder was synthesized with 67 mol % meta-phenylenediamine and isophthaloyl monomer units and 33 mol % para-phenylenediamine and terephthaloyl monomer units of the total. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 2:1. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 2:1. The weight average molecular weight was 590,000. This polymer powder and conductive carbon black particles (surface resistivity is 10 ⁴ Ω) were dissolved and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution. At this time, the mass concentration of the copolymerized aramid polymer was adjusted to 21% relative to the polymer solution, and the conductive carbon black was adjusted to 5% relative to the aramid polymer.

This polymer solution was spun under the conditions of Example 1 to obtain a wholly aromatic polyamide fiber. At this time, the boiling water draw ratio was 2.5 times, and the hot plate draw ratio was 3.2 times.
The resulting fiber had a fineness of 1.7 dtex, a breaking strength of 6.4 cN/dtex, a breaking elongation of 21%, a melting point of 304° C. and an electric resistivity of 2.69×10 ⁶ Ωcm.

[Comparative Example 4]
A copolymerized aramid polymer powder was synthesized with 67 mol % meta-phenylenediamine and isophthaloyl monomer units and 33 mol % para-phenylenediamine and terephthaloyl monomer units of the total. At this time, both isophthaloyl chloride and terephthaloyl chloride were used as acid chloride monomers so that the weight ratio was 2:1. As amine monomers, both meta-phenylenediamine and para-phenylenediamine were used in a weight ratio of 2:1. The weight average molecular weight was 660,000. This polymer powder and conductive carbon black particles (surface resistivity is 10 ⁴ Ω) were dissolved and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution. At this time, the mass concentration of the copolymerized aramid polymer was adjusted to 16% with respect to the polymer solution, and the conductive carbon black was adjusted to 45% with respect to the aramid polymer.

This polymer solution was spun under the conditions of Example 1 to obtain a wholly aromatic polyamide fiber. At this time, the boiling water draw ratio was limited to 1.1 times, and the hot plate draw ratio was limited to 2.5 times.
The resulting fiber had a fineness of 7.0 dtex, a breaking strength of 1.9 cN/dtex, a breaking elongation of 13%, a melting point of 313° C. and an electrical resistivity of 8.5 Ωcm.
Table 2 shows the physical properties of the fibers obtained in the above examples and comparative examples.

The conductive heat-resistant high-toughness fiber obtained by the present invention has heat resistance that can withstand a use environment of 290 ° C. or higher, and has a breaking strength of 3.5 to 10 cN / dtex and an elongation of 10% or more. It is a suitable fiber for applications that require heat resistance and flexibility such as. Moreover, since the electrical resistivity is 10 ³ Ωcm or less, exhibiting high conductivity that has never been reported, the use of the fiber of the present invention can impart high electrostaticity. Therefore, conventional conductive fibers with poor heat resistance could not exhibit their functions in high-temperature environments, whereas the fibers of the present invention can maintain high conductivity and electrostatic properties even in the same environments. It is possible, and it is useful not only for protective clothing, but also as a reinforcing fiber for resin structural materials that require electrostatic properties and are exposed to high temperature environments.

Claims (6)

An electrically conductive heat-resistant high-toughness fiber characterized by having an electrical resistivity of 10 ³ Ωcm or less, a breaking strength of 3.5 to 10 cN/dtex, a breaking elongation of 10 to 30%, and a melting point of 290° C. or higher. 2. The conductive heat-resistant high-toughness fiber according to claim 1, containing 6 to 40% by mass of conductive fine particles in the fiber. 3. The conductive heat-resistant high-toughness fiber according to claim 2, wherein the conductive fine particles are conductive carbon black. A copolymer aramid polymer in which the conductive heat-resistant high-toughness fibers are composed of a structure containing metaphenylene terephthalamide units and/or metaphenylene isophthalamide units and paraphenylene terephthalamide units and/or paraphenylene isophthalamide units. The conductive heat-resistant high-toughness fiber according to any one of claims 1 to 3, which is composed of coalescing. The conductive heat-resistant high-toughness fiber contains at least three structures selected from the group of meta-phenylenediamine, para-phenylenediamine, isophthaloyl, and terephthaloyl, meta-phenylenediamine and/or isophthaloyl monomer units, para-phenylenediamine and / Or the conductive heat-resistant high-toughness fiber according to any one of claims 1 to 4, wherein the molar ratio of terephthaloyl monomer units is in the range of 50 or more and less than 70:50 or less and more than 30. A method for producing a conductive heat-resistant high-toughness fiber, comprising:
A structure containing a meta-phenylene terephthalamide unit and/or a meta-phenylene isophthalamide unit and a para-phenylene terephthalamide unit and/or a para-phenylene isophthalamide unit, wherein the amide units are meta-phenylenediamine and para-phenylene Containing at least three structures selected from the group of diamine, isophthaloyl, and terephthaloyl, the molar ratio of meta-phenylenediamine and/or isophthaloyl monomer units to para-phenylenediamine and/or terephthaloyl monomer units is 50 or more and less than 70: Using a copolymerized aramid polymer having a weight average molecular weight in the range of 50 or less and greater than 30 and having a weight average molecular weight of 400,000 to 1,000,000, the following steps (1) to (5) are performed, and the manufacturing conditions of (6) A method for producing a conductive heat-resistant high-toughness fiber that satisfies the above.
(1). The copolymerized aramid polymer is dissolved in an amide solvent in the range of 10 to 30% by mass, and the conductive fine particles are dispersed in the aramid polymer at 6 to 40% by mass to prepare a spinning dope, which is passed through a spinneret,
(2). coagulated by spinning in an aqueous coagulation bath containing 1 to 20% by mass of an amide solvent;
(3). (4) washing with water in an aqueous washing bath, followed by drawing in a boiling water drawing bath in a range of 1.1 to 5.0 times; Perform dry heat treatment in the range of 100 to 250 ° C,
(5). While applying heat treatment in the range of 290 to 380 ° C., hot drawing is performed at a draw ratio of 2.0 to 10.0 times,
(6). The total draw ratio of the boiling water draw ratio and the hot draw ratio is 5 times or more.