RU2300581C2 - Method for producing of copolyamidobenzimidazole-based threads using alkaline processing - Google Patents

Abstract

FIELD: production of high-strength high-modulus threads, in particular, copolyamidobenzimidazole-based threads which may be used for reinforcement of plastics, technical rubber articles, fiber optics cables, as well as for creating of shell-proof jackets or safety helmets and other articles.

SUBSTANCE: method involves carrying-out low-temperature polycondensation synthesis of mixture of aromatic diamines of 5(6)-amino-,2-(para-aminophenyl) benzimidazole and paraphenylene diamine with terephthaloil chloride in amide solvent medium with salt admixture; providing wet or dry-wet forming from 4.0-5.1%-polycondensation solutions containing hydrogen chloride as by-product of polymer synthesis in aqueous-amide settling bath; washing resultant thread with water to remove solvent and providing alkaline processing of thread for neutralization of hydrogen chloride chemically bound with polymer and removal of produced chloride and excessive alkaline; finally washing thread with water and carrying-out drying, thermal processing and thermal draught; obtaining threads with neutral pH of aqueous extract after boiling process. Said threads have strength of up to 260 sN/tex, microplastic strength of up to 520 kgf/mm², modulus of elasticity of 15000-15300 kgf/mm², relative elongation at break of 2.6-3.3%.

EFFECT: improved strength characteristics of threads and wider range of usage.

4 cl, 4 ex

Description

The invention relates to a method for producing high-strength high-modulus yarns based on aromatic polyamides with heterocycles in the main chain, in particular copolyamidobenzimidazoles, which removes hydrogen chloride chemically bound to the polymer from the fiber. High-strength, high-modulus pH-neutral aqueous extract after boiling, the threads are intended for reinforcing plastics, rubber technical products, fiber optic cables, as well as for creating armor-resistant (body armor, helmets) and other materials.

The filaments of the present invention are obtained on the basis of SPABI synthesized based on 50-80 mol.% 5 (6) -amino-2- (paraaminophenyl) benzimidazole (hereinafter also referred to as heterocyclic diamine or abbreviated HCD), 20-50 mol.% Paraphenylenediamine (p -FDA) and 100 mol.% Terephthaloyl chloride (TPC) and, therefore, it has the following formula:

where m = 50-80, n = 20-50 and m + n = 100.

The synthesis of SPABI of a similar chemical structure, a molded product (filaments) based on the specified SPABI and the method for their preparation are described previously.

RF patent 646605 describes a method for producing a fiber-forming heterocyclic aromatic polyamide by polycondensation of 50-70 mol% of HCDA mixed with 30-50 mol% of p-PDA with 100 mol% of aromatic dicarboxylic acid chloride, including TPC, in DMAA (or N-methylpyrrolidone) in the presence of LiCl or CaCl ₂ . Receive 4.2-4.6% polycondensation SPABI solutions, which are used for forming filaments without neutralizing hydrogen chloride in them, a by-product of polymer synthesis. The formation of the thread is carried out wet through a die with 60 holes with a diameter of 0.1 mm into a precipitation bath containing 40% DMAA, 1.5-2.0% lithium or calcium chloride and the rest is water with a plasticizing extract from 30 to 100%, conducted in the air. The thread, thoroughly washed with demineralized water and dried, is heat treated at a temperature of 350 ° C for 30 minutes. A finished thread is obtained with a strength of 185-205 cN / tex, elongation at break of 4.1-6.0% and an elastic modulus of 7200-8700 kgf / mm ² .

From the RF patent 2017866, 1994, a molded product (filaments, films) obtained from SPABI is known, which is synthesized from 70 mol.% HCDA, 30 mol.% P-PDA and 100 mol.% TPC in an amide solvent with salt additive, from a polycondensation solution with a polymer concentration of 4.3% containing 2.8% LiCl, 0.97% HCl and DMAA with a viscosity of 54 Pa · s and a characteristic viscosity of the polymer [η] = 7.5 dl / g (determined in DMAA with 3% LiCl). The yarn is formed by the dry-wet method, in which the die is separated from the precipitation bath by an air gap of about 10 mm, using a 20% solution of DMAA in water at 20 ° C as a precipitation bath, through a 60-hole die with a diameter of 0.1 mm. Spinneret hood is negative, plasticizing hood is 70%. The speed of forming (receiving) threads 21 m / min The thread is passed through a washing bath, drying rollers at 136 ° C, heat treated at 340 ° C. After additional thermal elongation in air at 375 ° C, it has a linear density of 27.1 tex, the strength of the multifilament yarn 245 cN / tex, the elongation at break of 3.2%, the microplastic strength 450 kgf / mm ² and the elastic modulus 15700 kgf / mm ² .

From patent RF 2143504, 1999 a high-strength high-modulus thread is known, formed by dry-wet method from a 4.6% solution of SPABI, with [η] = 6.5 dl / g, synthesized by polycondensation of 70 mol.% HCDA, 30 mol % p-PDA and 100 mol% TPC in DMAA containing 2.8% lithium chloride. The thread was formed from an acidic solution without neutralizing HCl through a die with 80 holes with a diameter of 0.09 mm with a negative die drawing of jets equal to minus 50% during two-stage deposition of the polymer in the spinning thread using plasticization drawing of the thread by 120% between the deposition stages . For the first stage of polymer precipitation, a 7% solution of DMAA in water at 40 ° C was used. Forming speed 28 m / min. After washing and drying, the thread was subjected to heat treatment at 375 ° C and a subsequent thermal extraction of 1.5% at 385 ° C. Get a complex thread with high strength (strength in microplastics 612 kgf / mm ² ) and an elastic modulus of 17540 kgf / mm ² with a relative elongation at break of 1.8%. However, the described method for producing threads is quite complex and sensitive to small changes in parameters.

In the patent of the Russian Federation 2167961, 2001, it is proposed to obtain modified SPABI filaments by wet spinning from copolyamide containing units of 4,4'-diamino-3,3'-dichlorodiphenylmethane. With a 5% content of these links, i.e. at m = 70, n = 25, p = 5 and m + n + p = 100, the strength of the filaments reaches 230 cN / tex, and the relative tensile elongation is 3.4%. In this patent, spinning is carried out from acidic polycondensation solutions containing HCl. For the precipitation bath, water-amide mixtures (DMAA or N-methylpyrrolidone) with the addition of LiCl or CaCl _{2 are used} . The gel-like filaments obtained in a precipitation bath with a negative spinneret extraction equal to minus 50% are subjected to 100% plasticization stretching carried out in air, after which they are washed with demineralized water, dried at 100-120 ° C and heat treated.

From the patent of the Russian Federation 2058443, an alkaline treatment of threads based on SPABI is known to neutralize sulfuric acid residues at the stage of their final washing in the production process obtained from sulphate liquid crystal solutions. The copolymer in this patent consists of more than 90% of paraphenylene terephthalamide units and only 1 to 9% of units based on HCDA (SPABI with m = 1-9, n = 91-99). Therefore, the thread can be washed from sulfuric acid residues with water and without alkali addition, and in some examples of this patent there is no alkaline treatment. The strength of the complex filaments is 210 cN / tex, and their strength in microplastics does not exceed 360 kgf / mm ² .

A strength level of 245 cN / tex with a microplastic strength of 450 kgf / mm ² , an elongation at break of 3.2% and an elastic modulus of 15,700 kgf / mm ² is indicated for SPABI (m = 70, n = 30) of multifilament yarns in RF patent 2168567 , 2001 (prototype), wet formed from a polycondensation solution in DMAA with the addition of 2.9% LiCl containing HCl as a by-product of polymer synthesis with a polymer concentration of 4.2% and [η] = 10.5 dl / g. The molding is carried out through a die with 60 holes with a diameter of 0.1 mm with horizontal movement of the filament in a precipitation bath, which is a 55% solution of DMAA in water at a temperature of 20 ° C with a negative spinneret hood and 100% plasticizer hood. The thread is washed, dried at 130 ° C on drying rolls. After heat treatment at a temperature of 365 ° C for 30 minutes and additional thermal elongation in air at 380 ° C by 1%, a finished thread with a linear density of 29.4 tex with the above properties is obtained. In this patent, to improve the mechanical properties, a surface treatment of the fiber with a modifying polyorganohydride siloxane composition was proposed after drying before accepting the yarn for packaging.

From the analysis of patent sources it can be concluded that the formation of threads based on SPABI is carried out from acidic polycondensation solutions, i.e. solutions containing HCl as a by-product of polymer synthesis without neutralizing it. In this case, HCl, together with the solvent and salt, is transferred to a precipitation bath and washing water, and desalted water is used to wash the threads.

The processing of acidic SPABI solutions without neutralizing hydrogen chloride in them is explained by the accelerated precipitation of the polymer in the presence of HCl, which makes it possible to carry out effective plasticization drawing of threads, providing them with higher strength (Preprints of 4 International Symposium on Chemical Fibers. Kalinin, 1986, Volume 5, p. 78) . In addition, it is known that benzimidazole cycles in SPABI have the property of bases and form a chemical compound with HCl, which, for example, is manifested by two potential jumps on the potentiometric titration curve of HCl in a spinning solution using KOH (Chemical fibers, 1990, No. 2, s .58-60). The interaction of SPABI with HCl leads to a change in its molecular characteristics in solution, due to ionization and electrostatic repulsion of the same charged chain links and an increase in the transverse dimensions of the chain, taking into account the binding of HCl (Chemical fibers, 2002, No. 6, from 38-40), which cannot Do not affect the properties of the resulting filaments.

For the SPABI composition, in which m = 70, n = 30, 35% of hydrogen chloride chemically bound to the polymer (in salt form) and the remaining 65% HCl are free in the polycondensation solution, which makes up 7.99% of the polymer weight, respectively and 14.83%. Unlike free, polymer-bound HCl is only partially removed after thoroughly washing the continuously moving filament on the washing rollers of the spinning and finishing device heated with demineralized water to 40-60 ° C, while this washing provides almost complete removal of the solvent (up to hundredths fractions of a percent) and salt. HCl is present not only in the freshly formed yarn, but also in the finished yarn after heat treatment, which is fixed by the chemical method of titration of the excess alkali after two hours of boiling them in 0.01 N. alkaline solution or by the method of determining the pH of the aqueous extract after boiling the thread for two hours. So, a freshly formed, washed with water and dried yarn of linear density 58.8 tex of composition m = 70, n = 30 contains 2.2-2.4% HCl by weight of the polymer (its pH of the aqueous extract after boiling is 2.4-2, 6), which corresponds to a molar ratio of the remaining HCl to polymer heterocycles of about 30%. The pH of this thread after heat treatment is 3.0-3.4. Therefore, to remove all chemically bonded HCl with the polymer in the yarn, a long, many-hour treatment with hot water is required, which cannot be carried out under conditions of molding and continuous finishing of the yarn. These methods, apparently, do not record the entire amount of HCl in the threads if they were dried, since the threads contain much more HCl before drying, about 3.6% in the above example for a yarn with a linear density of 58.8 tex.

Treatment with a 0.05-0.3% alkali solution of a moving thread on the washing rollers for 0.3-3 minutes allows you to neutralize all the hydrogen chloride in the thread, and the resulting salt and excess alkali are removed by its final washing with demineralized water.

An object of the present invention is to obtain high-strength high-modulus yarns based on SPABI of the above composition with a neutral pH of their aqueous extract after boiling with the following indicators: linear density of 18-58.8 tex; strength of multifilament yarns (specific breaking load) up to 260 cN / tex; elongation at break of 2.6-3.3%; dynamic modulus of elasticity 15000-15300 kgf / mm ² ; the strength of multifilament yarns in microplastics up to 520 kgf / mm ^2; The pH of the aqueous extract after boiling is 6.0-8.5.

The technical problem is solved due to the fact that in the known method for producing high-strength high-modulus filaments by molding from 4.0-5.1% polycondensation solutions of SPABI in DMAA or N-methylpyrrolidone with the addition of lithium or calcium chlorides containing hydrogen chloride as a by-product polymer synthesis, into a water-amide precipitation bath with a negative spinneret drawing of jets, plasticizing drawing of a thread by 70-140%, washing of a thread, drying at 100 ° C, heat treatment at 350 ° C for 30 minutes and short-term thermal drawing yarn at 390 ° C by 1.0-1.5%, according to the invention, the washing of the thread is carried out in combination with the treatment with a dilute alkali solution or the treatment with an alkaline solution follows washing the thread, which neutralizes hydrogen chloride chemically bonded to the benzimidazole cycles of the polymer and removes the resulting salt and excess alkali by its final washing with demineralized water. The alkali content in the solution should be 0.05-0.3%. Processing time 0.3-3 minutes, temperature from 20 to 60 ° C. When the alkali concentration is less than 0.05%, the process of neutralizing hydrogen chloride in the filament increases in time and the pH of the filament can be less than 6.0. On the contrary, if the alkali concentration is more than 0.3%, then the subsequent relatively short-term washing of the filament from excess alkali with demineralized water is difficult and the pH of the filament can be more than 8.5. LiOH or Ca (OH) ₂ is used as the alkaline reagent if alkaline treatment is combined with washing the filaments from the solvent in accordance with the same cation of the salt additive in the solvent, or any alkaline reagent LiOH, Ca (OH) ₂ , NaOH, soda, solution ammonia and others, if the treatment is carried out after washing the threads from the solvent.

The washing method with the inclusion of alkaline treatment is suitable for producing neutral filaments based on copolyamidobenzimidazole not only of the above composition, but also of a homopolymer (m = 100, n = 0), as well as copolymers in which m is less than 50. As aromatic diamines for polymer synthesis in a mixture with 5 (6) -amino-2- (paraaminophenyl) benzimidazole, in addition to paraphenylenediamine, there may be other diamines, for example metaphenylenediamine, chloroparaphenylenediamine, diaminodiphenyl oxide, 5 (6) -amino-2- (paraaminophenyl) benzoxazole, etc., whose presence is not reflected on the ability of benzimidazole cycles to chemically bind hydrogen chloride released as a by-product of polymer synthesis.

The viscosity of polycondensation solutions is determined by the duration of the fall of the control steel ball in the medium of the solution at 20 ° C.

Specific viscosity (η _beats ), which is determined on a Ubbelode capillary viscometer for solutions of 0.5 g of dry polymer in 100 ml of 96% sulfuric acid at 20 ° C, is used as a characteristic of the molecular weight of SPABI.

The linear density of the complex filaments is determined by the gravimetric method.

Complex-based microplastics are made with an epoxy impregnating composition of the EDT-10 brand.

The strength of multifilament yarns and microplastics (specific tensile load), elongation at break is determined on a tensile testing machine using a clamping length of 250 mm, according to generally accepted methods.

The elastic modulus of complex filaments (dynamic) is determined by ultrasonic acoustics. To express the elastic modulus of the filaments in kgf / mm ^2, a polymer density of 1.45 g / cm ^{3 was} taken into account.

Mechanical tests are carried out for threads with a content of about 2.5% moisture.

The HCl content in a freshly formed yarn is determined by boiling 3-5 g of a sample, weighed to the nearest 0.0002 g, in 100 ml of precisely prepared 0.01 N NaOH solution, for 2 hours under reflux and titration of 10 ml of extract of 0.01 N. HCl solution with phenolphthalein.

The pH of the aqueous extract is determined by boiling 5 g of the thread, weighed to the nearest 0.01 g, in 50 ml of distilled water for 2 hours under reflux and measuring its pH.

The invention is illustrated by the following examples.

Example 1

A thread based on copolyamidobenzimidazole (SPABI) of 70:30, i.e. synthesized from 70 mol.% 5 (6) amino-2- (paraaminophenyl) benzimidazole (hereinafter abbreviated as heterocyclic diamine or HCDA), 30 mol.% paraphenylenediamine (p-PDA) and terephthaloyl chloride (TLC) with a neutral pH of the aqueous extract after boiling by combining alkaline treatment with solvent washing.

For polymer synthesis, 10.870 g (0.04847 mol) of HCDA, 2.246 g (0.02077 mol) of p-PDA and 14.613 g of lithium chloride are dissolved with stirring in 500 ml of DMAA under ordinary temperature conditions (18-24 ° C) in an inert atmosphere nitrogen. The water content in the reaction medium is 0.035%. After the diamines are dissolved, the solution is cooled to 8-10 ° C and TLC is added with constant stirring over 50 minutes. The polymer synthesis is exothermic. Therefore, it is necessary to remove heat, maintaining the temperature of the reaction medium 15-20 ° C. At the beginning, a portion of TPC is added in an amount of 98% of the equimolar and then the remaining amount in small portions, controlling the synthesis to increase the viscosity of the solution within the required limits. In total, 14.019 g (0.06905 mol) or 99.7% of TPC from equimolar are added. The viscous copolyamide solution is additionally stirred for 0.5 hours at 22-25 ° C. Get a solution with a viscosity of 65 PA · s and the specific viscosity of the polymer η _beats. = 8.5. The solution contains 4.30% polymer, 2.84% LiCl, 0.98% HCl and the rest is DMAA.

The solution is filtered, degassed and a thread is formed from it through a wet method through a die for 100 holes with a diameter of 0.08 mm under ordinary temperature conditions (18-24 ° C), feeding the solution to a die 3.60 g / min. As a precipitation bath, a solution of 50% DMAA, 48% water and 2% LiCl is used, in which a pH of about 5-6 dosed LiOH is maintained to neutralize the incoming HCl with SPABI solution. Spinneret drawing of the jets is negative, close to minus 49%, plasticizing drawing by 120%, which is carried out in air in an entrained layer of a precipitation bath under ordinary conditions. Combine alkaline treatment with washing the threads from the solvent. For this, a continuously moving thread at a speed of 8 m / min is treated on the first pair of washing rollers, on which 24 meters of thread are wound, with a solution of 20% DMAA, 0.6% LiCl, 0.05% LiOH, the rest is water with a temperature of 20 ° With dipping and irrigation with a flow of 60 l / h of the specified solution. Next, the thread on two subsequent pairs of washing rollers is finally washed from all components with demineralized water at 20 ° C, dried on a drying roller at 100 ° C and taken onto a cartridge with a twist of about 50 torsions per meter, the pH of the aqueous extract after boiling the thread after drying 6, 0. If the same washing is used in a similar way, but without dosing LiOH into the solution on the first pair of rollers, an acidic filament is obtained with a pH of the aqueous extract after boiling, after drying, equal to about 2.0 and an HCl content of about 3.5%. After heat treatment at 350 ° C for 30 minutes and a heat extract at 390 ° C by 1.0%, yarns with a linear density of about 20 tex are obtained with the following indicators for a neutral yarn P / U / E / α / pH = 200 / 2.6 / 15100/490 / 7.2 and for comparison, the same indicators for the acid thread P / U / E / α / pH = 210 / 2.5 / 15300/455 / 3.0, where P is the strength (relative breaking load) of the complex filaments, cH / tex; Y - relative tensile elongation,%; E - dynamic modulus of elasticity of the thread, kgf / mm ² ; α is the strength of the multifilament yarn in microplastics, kgf / mm ² ; pH is the pH of the aqueous extract after boiling the thread.

From a comparison of the mechanical properties of the yarns, we can conclude that they are close, except for the strength of the yarn in microplastics, which is higher for a neutral yarn compared to an acid one.

Example 2

80:20 SPABI-based yarn obtained by dry-wet spinning from a 5.1% SPABI polycondensation solution in DMAA containing CaCl ₂ and HCl with a neutral pH of the aqueous extract after boiling by combining alkaline treatment with solvent washing.

The polymer synthesis is carried out as described in example 1. 29.136 g (0.12992 mol) of HCC, 3.512 g (0.03248 mol) of p-PDA and 32.970 g (0.1624 mol) of TPC, 1000 ml of DMAA are used for the synthesis. with a content of 2.8% CaCl ₂ and 0.045% water. Get a solution with a viscosity of 90 PA · s, η _beats = 7.0. The solution contains 5.10% polymer, 2.63% CaCl ₂ , 1.12% HCl and DMAA. This solution is used for spinning.

The SPABI solution is filtered, dosed and the yarn is spun according to the dry-wet method according to Russian patents 2017866 and 2168567, extruding through spinneret channels (60 holes with a diameter of 0.1 mm) into an air gap of 10 mm in size and into a precipitation bath containing 20% solution of DMAA in water with a small amount of CaCl ₂ and HCl released together with DMAA from SPABI solution at a temperature of 20 ° C. The flow rate of the solution to the die is 12.0 g / min. The yarn is formed with a negative spinneret hood equal to minus 51% and a plasticizer hood of 70%, which is carried out in air in a sedimentation bath layer carried away with the thread at 20 ° C. A continuously moving thread at a speed of 21 m / min is treated on the first pair of washing rollers, on which 20 meters of thread are wound, with a solution of 20% DMAA, 0.6% CaCl ₂ and 0.3% Ca (OH) ₂ , the rest is water with temperature of 20 ° C by dipping and irrigation with a feed of 60 l / h of the specified solution. Next, the thread on the next two pairs of washing rollers is finally washed from all components with demineralized water at a temperature of 40-60 ° C, dried on a drying roller at 100 ° C and taken onto a cartridge with a twist of about 50 torsions per meter, after which the thread is analyzed. The pH of the aqueous extract after boiling the strand is 7.4. After heat treatment at 350 ° C for 30 minutes and a temperature hood at 390 ° C by 1.5%, a thread of linear density 29.9 tex is obtained with the following indicators: P / U / E / α / pH = 217/33/15000/506 / 8.0.

Example 3

A 70:30 SPABI-based thread obtained by wet spinning from a polycondensation solution similar to that described in Example 1 with a neutral pH of the aqueous extract after boiling by alkaline treatment after washing the thread from the solvent.

Polycondensation solutions of SPABN are used, the preparation method of which and the composition is similar to that described in Example 1, with a viscosity of 60-70 Pa · s, specific viscosity of the polymer η _beats = 8.0-8.7, with a content of 4.30% of the polymer, 2.84 % LiCl, 0.98% HCl and the rest is DMAA.

The solution is filtered, degassed, and filaments are formed from it by the wet method through a 300-hole spinneret with a diameter of 0.08 mm under ordinary temperature conditions (18-24 ° C). Feeding the solution to a die 20.0 g / min. As a precipitation bath, a solution of 50% DMAA, 48% water and 2% LiCl is used, in which the pH is maintained at about 4-6 with a dosage of LiOH to neutralize the incoming HCl with SPABI solution. Spinneret drawing of the jets is negative, close to minus 51%, plasticizing drawing of 130%, which is carried out in air in a bed of a precipitation bath carried away with a thread under ordinary temperature conditions. A continuously moving thread at a speed of 15 m / min is washed from solvent, salt and free HCl on the first pair of rollers with demineralized water at a temperature of 50 ° C. On the second pair of rollers, it is treated with a dilute alkali solution in demineralized water by dipping and irrigation with a flow of 60 l / h at a temperature of 60 ° C. On the third pair of rollers, the thread is washed from salt and excess alkali with demineralized water at a temperature of 60 ° C. Next, the thread is dried on a drying roller at 100 ° C and taken onto a cartridge with a twist of about 50 torsions per meter, after which the pH of the aqueous extract is determined after boiling the thread. A different number of meters of thread is wound on a second pair of rollers and different concentrations of alkaline reagent are used.

When processing 5, 10, 15 and 20 meters of the thread, the following pH values of the aqueous extract are obtained after boiling the thread: 2.6, 3.0, 4.5, 6.0 - when using a 0.05% NaOH solution with a temperature of 60 ° C ; 6.0, 8.5, 8.5, 8.5 - when using a 0.25% NaOH solution and 60 ° C; 4,5; 6.0; 7.0; 7.4 - when using a 0.3% solution of ammonia and 25 ° C. Moreover, if the pH of the aqueous extract after boiling the filament, after drying, is about 6.0, then its pH when taken wet before drying is 5.5, and the HCl content is not more than 0.1%. For comparison, a similar washing of 20 meters of thread on the second and third pair of rollers with demineralized water at 60 ° C without treatment with alkali provides a pH of the aqueous extract after boiling the thread at 2.4 and an HCl content of 2.5%, and its content when taken wet before drying, equal to 2.0 and 3.6%, respectively.

After heat treatment at 350 ° C for 30 minutes and a thermal hood at 390 ° C by 1.5%, a yarn with a linear density of 58.8 tex is obtained with the following indicators for a neutral yarn

P / U / E / α / pH = 261 / 3.1 / 15100/520 / 7.6

and for comparison, the same indicators for a sour thread

P / U / E / α / pH = 254 / 3.1 / 15100/490 / 3.2.

Example 4

A 50:50 SPABI-based thread obtained by wet spinning from a polycondensation solution in N-methylpyrrolidone with CaCl ₂ , with a neutral pH of the aqueous extract after boiling by alkaline treatment after washing the thread from the solvent.

The synthesis of the polymer is carried out as described in example 1. For the synthesis, 8.477 g (0.03780 mol) of HCDA, 4.088 g (0.03780 mol) of p-PDA and 15.349 g (0.07560 mol) of TPC, 500 ml of N are used. -methylpyrrolidone with a content of 0.030% water and 17.0 g CaCl ₂ (with a moisture content of not more than 0.05%). Get a solution with a viscosity of 80 PA · s and η _beats = 12.0. The solution contains 4.0% polymer, 3.03% CaCl ₂ , 0.98% HCl, and the rest is N-methylpyrrolidone.

Spinning is carried out as described in example 1 through a spinneret per 100 holes with a diameter of 0.08 mm while maintaining the flow rate of the spinneret equal to 3.60 g / min, but with a change in the values of spinnerets and plasticizing hoods, which are respectively equal about minus 49% and 140%, and using a precipitation bath of 40% N-methylpyrrolidone, 2.0% CaCl ₂ and 58% water at 20 ° C and pH = 4-6.

The washing of the filament from the solvent, followed by treatment with a 0.2% soda solution and washing of salt and excess soda is carried out on three pairs of rollers with a filament speed of 8 m / min, as described in Example 3. The filament is dried on a drying roller at 100 ° C and take on a cartridge with a twist of about 50 torsions per meter. Next, the thread is heat treated at 350 ° C for 30 minutes. A neutral and acidic filament (without soda treatment) of a linear density of 18.5 tex with a strength of one and the other of about 180 cN / tex is obtained. Their strengths are close, but the pH of the aqueous extract after boiling differ significantly - respectively 7.0 and 3.6.

Claims (4)

1. A method of producing a filament based on copolyamidobenzimidazole synthesized by low-temperature polycondensation of a mixture of aromatic diamines 50-80 mol.% 5 (6) -amino-2- (paraaminophenyl) benzimidazole and 20-50 mol.% Paraphenylenediamine with 100 mol.% Terephthaloyl chloride in a medium dimethylacetamide or N-methylpyrrolidone with the addition of lithium or calcium chlorides, wet or dry-wet molding from 4.0-5.1% polycondensation solutions containing hydrogen chloride as a by-product of polymer synthesis into a water-amide precipitation bath with a negative solid spherical drawing of jets, plasticizing drawing of the thread by 70-140%, washing the threads from the solvent with water, drying at 100 ° C, heat treatment at 350 ° C and thermal drawing of the thread at 390 ° C by 1.0-1.5%, differing the fact that the washing operation includes an alkaline treatment to neutralize the hydrogen chloride chemically bound to the polymer to remove the chloride formed and excess alkali by final washing with water. 2. The method according to claim 1, characterized in that the continuously moving thread is treated with a solution of alkali when it is washed from a solvent, introducing alkali into a washing bath containing up to 20% dimethiacetamide or N-methylpyrrolidone, up to 0.6% LiCl or CaCl ₂ , 0.05-0.3% LiOH or Ca (OH) ₂ , the rest is water. 3. The method according to claim 1, characterized in that the continuously moving yarn washed from the solvent is treated with a 0.05-0.3% solution of LiOH, Ca (OH) ₂ , NaOH, Na ₂ CO ₃ or ammonia in demineralized water at 20-60 ° C for 0.3-3.0 minutes, followed by its final washing from chloride and excess alkali with demineralized water. 4. The method according to any one of claims 1 to 3, characterized in that the filaments are obtained with a pH of the aqueous extract after boiling 6.0-8.5, the strength of the complex filaments up to 260 cN / tex, and their microplastic strength up to 520 kgf / mm ² , modulus of elasticity 15000-15300 kgf / mm ² and elongation at break of 2.6-3.3%.