A method for preparing a poly-p-phenylene terephthalamide (PPTA) fiber paper containing a flexible chain segment

Abstract

The application relates to a preparation method of a flexible chain segment-containing poly-p-phenyleneterephthalamide (PPTA) fiber paper, which comprises the following steps: uniformly mixing PPTA finished short fibers and flexible chain segment-containing PPTA sedimentation fibers, and performing heat pressing and drying to obtain the flexible chain segment-containing PPTA high-performance fiber paper. The PPTA fiber paper prepared by the method has excellent performance, the preparation process is simple, the requirement for equipment is low, and the industrialized production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to a preparation method of a poly-p-phenyleneterephthalamide PPTA fiber paper containing a flexible chain segment. BACKGROUND

[0002] Thanks to the characteristics of a large bond energy, strong rigidity and strong interaction between molecular chains of PPTA, PPTA products usually have excellent thermal performance, mechanical performance, electrochemical stability and are widely used in the fields of national defense and military industry, aerospace and the like, and are an ideal material for preparing high-performance fiber paper. However, since PPTA is difficult to be dissolved in conventional organic solvents and has a melting point higher than its decomposition temperature, it is difficult to realize effective interface bonding between the PPTA spunlaid fibers and the chopped fibers in a micro-melt state through a traditional hot-pressing process, which affects the overall mechanical performance of the fiber paper. Therefore, it is very important to improve the interface bonding force between the two phases in the fiber paper.

[0003] Chinese patent CN 101687382A discloses a honeycomb structure of a poly-p-phenyleneterephthalamide paper containing aliphatic polyamide adhesives and an article made of the honeycomb structure. The method is to blend different proportions of aliphatic polyamide adhesives such as nylon 610, nylon 6 and nylon 66 as void-filling thermosetting resins with PPTA fibers, hot-pressing processing to obtain PPTA fiber paper with excellent mechanical properties. However, the PPTA fiber paper prepared by this method contains a relatively high content of aliphatic structure, which inevitably affects the overall thermal performance, electrical insulation performance and chemical stability of the paper.

[0004] Chinese patent CN 114481677A discloses a modified para-aramid paper (PPTA paper) and a preparation method and application thereof. In the method, para-phenylenediamine, terephthaloyl chloride and a fluorescent unit having an aggregation-induced emission property are used as raw materials for polymerization to obtain a polymerization product, and the modified para-aramid coarse fibers are obtained after stirring, crushing and drying. The modified para-aramid fiber dispersion liquid is obtained by alkali treatment, and the para-aramid paper with excellent tensile strength and fluorescence performance is obtained after vacuum filtration and hot-pressing. However, the para-aramid paper prepared by this method has weak internal interaction, low rigidity and poor tear strength, which is difficult to meet the market demand for high-performance PPTA fiber paper. SUMMARY

[0005] In view of the defects of the prior art, the technical problem to be solved by the present application is to provide a preparation method of a poly-p-phenyleneterephthalamide PPTA fiber paper containing a flexible chain segment, which overcomes the defects of the prior art such as complex production process, high cost and poor tear resistance of the para-aramid paper.

[0006] The application discloses a flexible chain segment-containing poly-p-phenyleneterephthalamide (PPTA) fiber paper, and the fiber paper component comprises flexible chain segment-containing PPTA fibers and PPTA short fibers.

[0007] Preferably, the flexible chain segment-containing PPTA fibers are flexible chain segment-containing PPTA spun fibers, and the structure of the flexible chain segment-containing PPTA comprises:

[0008]

[0009] one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylacetamide and benzimidazole ionic liquid; and the content of the cosolvent in the solvent system is 5% to 20% (wt).

[0010] Preferably, the mass ratio of the PPTA short fibers to the flexible chain segment-containing PPTA spun fibers is 2:8 to 6:4; the diameter of the PPTA short fibers is 10 to 30 microns; and the length of the PPTA short fibers is 4 to 8 mm.

[0011] The application further discloses a preparation method of the flexible chain segment-containing PPTA fiber paper.

[0012] (1) preparing a PPTA solution with low polymerization degree by controlling the molar ratio of p-phenylenediamine (PPDA) to terephthaloyl chloride (TPC) in a dry inert gas system and through low-temperature solution polycondensation, and then performing secondary copolymerization of the PPTA solution with a flexible chain segment-containing prepolymer with a certain polymerization degree to obtain a flexible chain segment-containing PPTA solution;

[0013] (2) diluting the flexible chain segment-containing PPTA solution to a solid content of 2 to 6 wt%, and then injecting the solution into a high-speed shearing coagulation bath to be coagulated and formed into flexible chain segment-containing PPTA spun fibers;

[0014] (3) mixing the flexible chain segment-containing PPTA spun fibers and the PPTA short fibers, and performing hot pressing and drying to obtain the flexible chain segment-containing PPTA fiber paper.

[0015] Preferably, the molar ratio of the PPDA to the TPC in the step (1) is 0.9 to 1.1; and the PPTA solution prepared through the polycondensation has a polymerization degree of 10 to 40.

[0016] Preferably, the solvent used in the step (1) is a polar solvent system, wherein the polar solvent system comprises a solvent and a cosolvent; the solvent is one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylacetamide and benzimidazole ionic liquid; the cosolvent is one or more of alkali metal or alkaline earth metal chlorides; and the content of the cosolvent in the solvent system is 5% to 20% (wt).

[0017] The co-solvent includes at least one of lithium chloride and calcium chloride.

[0018] Preferably, the flexible chain segment-containing prepolymer in step (1) is one or more of ether bond, sulfur bond, sulfone bond, aliphatic, diacetylene, cycloaliphatic, substituted p-phenylene, and m-phenylene structure; the polymerization degree of the flexible chain segment-containing prepolymer is 1-40, and the end group is terminated by an acyl chloride group or an amine group.

[0019] Further preferably, the structure of the flexible chain segment-containing prepolymer is one or more of the following (labeled as A-I):

[0020] A:

[0021] B:

[0022] C:

[0023] D:

[0024] E:

[0025] F:

[0026] G:

[0027] H:

[0028] wherein n = 1-40.

[0029] Preferably, the molar ratio of the secondary copolymerization PPTA to the flexible chain segment-containing prepolymer in step (1) is 0.1-10.

[0030] Preferably, the temperature of the low-temperature solution polycondensation in step (1) is -15°C-15°C, and the time is 10 min-60 min; the temperature of the secondary copolymerization is 5°C-20°C, and the time is 30 min-90 min.

[0031] Preferably, the coagulation bath in step (2) is a mixture of 0wt%-80wt% non-solvent and solvent; wherein the non-solvent is one or more of non-polar solvents; and the solvent is one or more of N-methyl pyrrolidone, N-ethyl pyrrolidone, N,N-dimethylacetamide, and benzimidazole ionic liquid.

[0032] Further, the non-solvent is one or more of water, ethanol, and other non-polar solvents.

[0033] The flexible chain segment PPTA solution in the step (2) is injected into the high-speed shearing solvent / non-solvent mixed system, the flexible chain segment PPTA solution droplets are broken and dispersed by stirring, stretched and deformed under the shearing action, and start to solidify and form under the action of the non-solvent, to obtain the flexible chain segment PPTA sedimentation fiber.

[0034] Preferably, the diameter of the flexible chain segment PPTA sedimentation fiber in the step (2) is 50-800 microns.

[0035] Preferably, the mass ratio of the PPTA short-cut fiber to the flexible chain segment PPTA sedimentation fiber in the step (3) is 2:8-6:4, the diameter of the PPTA short-cut fiber is 10-30 microns, and the length is 4-8 mm.

[0036] Preferably, the hot-pressing temperature in the step (3) is 200-350 DEG C, the hot-pressing pressure is 5-15 MPa, and the hot-pressing time is 10-50 min.

[0037] The application provides a flexible chain segment PPTA fiber paper prepared by the method.

[0038] The application provides an application of the flexible chain segment PPTA fiber paper in the fields of insulating materials and honeycomb core materials, such as high-temperature-resistant heat-insulating materials, honeycomb core materials and high-performance paper-based composite materials.

[0039] The flexible chain segment PPTA fiber paper has high interfacial shear strength, high overall rigidity and excellent tear strength.

[0040] The application selects a prepolymer with a flexible structure to prepare the flexible chain segment PPTA sedimentation fiber, and the flexible chain segment PPTA sedimentation fiber which can show micro-melting in the hot-pressing process is used as a filler and a binder to prepare the PPTA fiber paper through hot-pressing and drying.

[0041] Advantageous effects

[0042] (1) The application uses monomers with a flexible structure to prepare the flexible chain segment PPTA sedimentation fiber, the reactivity of the monomers is relatively weakened, the polymerization reaction process of the flexible chain segment PPTA solution with high stability is easier to control, and the subsequent processing and application are facilitated.

[0043] (2) The application uniformly disperses the PPTA short-cut fiber and the flexible chain segment PPTA sedimentation fiber in water, and hot-presses and dries to obtain the flexible chain segment PPTA fiber paper, so that the processability is high, the process is simple, and the industrialized production is facilitated.

[0044] (3) The present application selects PPTA fibrid containing flexible chain segments which can exhibit micro-melting phenomenon in the hot-pressing process as a filler and a binder, the presence of the flexible chain segments can effectively destroy the overall arrangement regularity of the molecular chains and weaken the interaction between the molecular chains, the micro-melting phenomenon occurs on the surface of the PPTA fibrid containing flexible chain segments in the hot-pressing process, the interaction between the interfaces of each part in the paper is improved, and the overall mechanical property of the PPTA fibrid paper is improved. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 Scanning electron microscope images of examples. DETAILED DESCRIPTION

[0046] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. Furthermore, it should be understood that after reading the content of the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope of the appended claims of the present application.

[0047] PPTA short-cut fibers with a diameter of 10 μm and lengths of 6 mm, 8 mm and 9 mm were purchased from Yantai Taihe New Material Co., Ltd.

[0048] The structure of the pre-polymer containing flexible chain segments used is numbered as B:

[0049]

[0050] The structure of the pre-polymer containing flexible chain segments used is numbered as E:

[0051]

[0052] In the present application, the performance of the PPTA paper is measured by the following method:

[0053] (1) Observation of sample morphology

[0054] An SU8010 cold field emission scanning electron microscope (SEM) was used to scan the morphology of the fibrid and the paper-based material prepared therefrom, and the acceleration voltage was 10 kV.

[0055] (2) Mechanical property test

[0056] A Mettler C44-104 universal electronic testing machine was used to test the mechanical property of the PPTA paper, the sample width was 10 mm, the clamping distance was 20 mm, the test temperature was room temperature, the tensile speed was 5 mm / min, and the tensile strength test of the paper was performed; an IMT-224 tearing strength tester was used to test the tearing resistance of the PPTA paper according to the sample preparation standard of ASTM D624-2012.

[0057] (3) Dynamic mechanical property (DMA) test

[0058] The thermal mechanical property of the prepared PPTA paper was determined by using a DMA1 type Mettler dynamic mechanical analyzer, the sample size was a sample of 10 mm x 5 mm, the temperature rising rate was 5 ℃ / min, the temperature rising range was 30-400 ℃, the frequency was 1 Hz, and the test was carried out under the tension mode.

[0059] Example 1

[0060] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% of cosolvent content) solution was added to a three-necked flask, and 0.04 mol of PPDA monomer was added, and stirred at room temperature until completely dissolved, and then the reaction device was transferred to a refrigerated circulating bath and cooled to -10 ℃, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 19 was obtained, and 0.01 mol of a pre-polymer containing flexible segments with a degree of polymerization of 20 numbered B was added, and the reaction temperature was 5 ℃, and after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0061] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, the PPTA solution droplets were stretched and deformed, and at the same time, under the action of the non-solvent H2O, the PPTA solution droplets began to solidify and form, and PPTA fibers containing flexible segments were obtained.

[0062] (3) The PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of the short fibers to the fibers was controlled to be 2:8, and the mixture was hot-pressed at 280 ℃ and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0063] The SEM image of the obtained PPTA fiber paper is shown in Figure 1 (b), the glass transition temperature of the paper obtained by DMA test was 295 ℃, the tear index of the paper was 32 mN·m 2 ·g -1 , and the tensile strength was 54.3 MPa.

[0064] Example 2

[0065] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.01 mol of pre-polymer with flexible chain segments numbered B with a degree of polymerization of 20 was added, and the reaction temperature was 5°C, after 30 min of reaction, a PPTA solution containing flexible chain segments was obtained, which was diluted to a solid content of 2wt% for standby.

[0066] (2) The PPTA solution containing flexible chain segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shear, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to coagulate and form, obtaining PPTA fibers containing flexible chain segments.

[0067] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible chain segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 2:8, and then it was hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible chain segments.

[0068] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (c), the DMA test showed that the glass transition temperature of the paper was 294°C, the tear index of the paper was 33 mN·m 2 ·g -1 , and the tensile strength was 56.2 MPa.

[0069] Example 3

[0070] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.01 mol of pre-polymer containing flexible segments with a degree of polymerization of 20 numbered E was added, and the reaction temperature was 5°C, after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0071] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shear, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0072] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 2:8, and then it was hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0073] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (d), the DMA test showed that the glass transition temperature of the paper was 290°C, the tear index of the paper was 35 mN·m 2 ·g -1 , and the tensile strength was 57.4 MPa.

[0074] Example 4

[0075] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.01 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction temperature was 5°C, after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0076] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shear, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0077] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 2:8, and then it was hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain PPTA fiber paper containing flexible segments.

[0078] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (e), the DMA test showed that the glass transition temperature of the paper was 295°C, the tear index of the paper was 35.9 mN·m 2 ·g -1 , and the tensile strength was 59.1 MPa.

[0079] Example 5

[0080] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0081] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0082] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 2:8, and then they were hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain PPTA fiber paper containing flexible segments.

[0083] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (g), the glass transition temperature of the paper obtained by DMA test was 289°C, the tear index of the paper was 36.3 mN·m 2 ·g -1 , and the tensile strength was 62.3 MPa.

[0084] Example 6

[0085] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, and after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 4 wt% for standby.

[0086] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0087] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 2:8, and then it was hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0088] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (f), the DMA test showed that the glass transition temperature of the paper was 289°C, the tear index of the paper was 36 mN·m 2 ·g -1 , and the tensile strength was 60 MPa.

[0089] Example 7

[0090] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0091] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0092] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 3:7, and then they were hot-pressed at 280°C and 10 MPa for 10 min, and then dried to obtain PPTA fiber paper containing flexible segments.

[0093] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (h), the glass transition temperature of the paper obtained by DMA test is 285°C, the tear index of the paper is 36.5 mN·m 2 ·g -1 , and the tensile strength is 64 MPa.

[0094] Example 8

[0095] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, and after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0096] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shear, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to coagulate and form, obtaining PPTA fibers containing flexible segments.

[0097] (3) PPTA short fibers with a diameter of 10 μm and a length of 6 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 3:7, and then the mixture was hot-pressed at 310°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0098] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (i), the DMA test showed that the glass transition temperature of the paper was 285°C, the tear index of the paper was 38 mN·m 2 ·g -1 , and the tensile strength was 67 MPa.

[0099] Example 9

[0100] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stable, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, and after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2wt% for standby.

[0101] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0102] (3) PPTA short fibers with a diameter of 10 μm and a length of 8 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 3:7, and then it was hot-pressed at 310°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0103] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (j), the DMA test showed that the glass transition temperature of the paper was 285°C, the tear index of the paper was 36.4 mN·m 2 ·g -1 , and the tensile strength was 59.8 MPa.

[0104] Comparative Example 1

[0105] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5 wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stabilized, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2 wt% for standby.

[0106] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0107] (3) PPTA short fibers with a diameter of 10 μm and a length of 9 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 3:7, and then the mixture was hot-pressed at 310°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0108] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (k) The DMA test showed that the glass transition temperature of the paper was 285°C, the tear index of the paper was 31.4 mN·m 2 ·g -1 , and the tensile strength was 54.1 MPa.

[0109] Comparative Example 2

[0110] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulating bath and cooled to -10°C, after the temperature of the reaction system was stable, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, a uniform and stable PPTA polymer system with a degree of polymerization of 21 was obtained, terminated by acyl chloride groups; 0.216 mol of pre-polymer containing flexible segments with a degree of polymerization of 40 numbered E was added, and the reaction was continued at a temperature of 5°C, and after 30 min of reaction, a PPTA solution containing flexible segments was obtained, which was diluted to a solid content of 2wt% for standby.

[0111] (2) The PPTA solution containing flexible segments obtained in step (1) was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring, and at the same time, under the action of shearing, they were stretched and deformed, and at the same time, under the action of non-solvent H2O, they began to solidify and form, obtaining PPTA fibers containing flexible segments.

[0112] (3) PPTA short fibers with a diameter of 10 μm and a length of 8 mm were mixed into the PPTA fibers containing flexible segments obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 7:3, and then the mixture was hot-pressed at 310°C and 10 MPa for 10 min, and then dried to obtain a PPTA fiber paper containing flexible segments.

[0113] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (l), the DMA test showed that the glass transition temperature of the paper was 293°C, the tear index of the paper was 30.4 mN·m 2 ·g -1 , and the tensile strength was 49 MPa.

[0114] Comparative Example 3

[0115] (1) In a dry system with humidity less than 50% under the protection of nitrogen atmosphere, 100 mL of NMP-CaCl2 (5wt% cosolvent content) solution was added to a three-necked flask, and 0.036 mol of PPDA monomer was added, stirred at room temperature until completely dissolved, then the reaction device was transferred to a refrigeration circulation bath and cooled to -10°C, after the temperature of the reaction system was stable, 0.044 mol of TPC monomer was added, and the reaction was stirred rapidly, at this time the viscosity of the system increased rapidly, and after 10 min of reaction, it was basically stable, obtaining a uniform and stable PPTA polymer system with acyl chloride group terminated and a polymerization degree of 21, which was diluted to a solution with a solid content of 2wt% for standby.

[0116] (2) The PPTA dilute solution obtained in step (1) without flexible chain segment was injected into a high-speed sheared 80% NMP-H2O mixed solvent, and the PPTA solution droplets were broken and dispersed by stirring at the same time, and were stretched and deformed under the action of shearing, at the same time, under the action of non-solvent H2O, the PPTA fibers were obtained by coagulation and molding.

[0117] (3) The PPTA short fibers with a diameter of 10 μm and a length of 8 mm were mixed into the PPTA fibers obtained in step (2), and the mass ratio of short fibers to fibers was controlled to be 3:7, and then the mixture was hot-pressed at 310°C and 10 MPa for 10 min, and then dried to obtain the PPTA fiber paper containing flexible chain segment.

[0118] The SEM image of the PPTA fiber paper obtained by testing is shown in Figure 1 (a), the paper has no glass transition temperature, the paper tear index is 15 mN·m 2 ·g -1 , and the tensile strength is 29 MPa.

Claims

1. A paper containing flexible segmental poly(p-phenylene terephthalamide) (PPTA) fiber, characterized in that, The fiber paper component includes PPTA fibers containing flexible segments and PPTA chopped fibers. The PPTA fiber containing flexible segments is a precipitated PPTA fiber containing flexible segments, wherein the structure of the PPTA containing flexible segments is as follows: One or more of the following; where m = 21-40; n = 1-40; The mass ratio of the PPTA chopped fibers to the PPTA precipitated fibers containing flexible segments is 2:8 to 6:4; the PPTA chopped fibers have a diameter of 10 to 30 μm and a length of 4 to 8 mm. The preparation method of the PPTA precipitate fiber containing flexible segments includes the following steps: (1) In a dry inert gas system, p-phenylenediamine (PPDA) and terephthaloyl chloride (TPC) are subjected to low-temperature solution polycondensation to obtain a PPTA solution, and then the PPTA solution is subjected to secondary copolymerization with a prepolymer containing flexible segments to obtain a PPTA solution containing flexible segments; (2) The PPTA solution containing flexible segments is diluted and then injected into a shearing coagulation bath to solidify and form a PPTA precipitate fiber containing flexible segments.

2. A method for preparing the flexible segment poly(p-phenylene terephthalamide) (PPTA) fiber paper according to claim 1, comprising the following steps: (1) In a dry inert gas system, p-phenylenediamine (PPDA) and terephthaloyl chloride (TPC) are subjected to low-temperature solution polycondensation to obtain a PPTA solution. Then, the PPTA solution is copolymerized with a prepolymer containing flexible segments to obtain a PPTA solution containing flexible segments. (2) Dilute the PPTA solution containing flexible segments, and then inject it into a shearing coagulation bath to solidify and form fibers containing PPTA precipitates. (3) Mix PPTA precipitated fibers containing flexible chain segments and PPTA short-cut fibers, and then hot-press and dry them to obtain PPTA fiber paper containing flexible chain segments.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of p-phenylenediamine (PPDA) to terephthaloyl chloride (TPC) is 0.9–1.1; the PPTA solution prepared by condensation has a degree of polymerization of 21–40. The solvent used in step (1) is a polar solvent system, which includes a solvent and a co-solvent; wherein the solvent is one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylacetamide, and benzimidazole ionic liquids; and the co-solvent is one or more of alkali metal or alkaline earth metal chlorides, and the content of the co-solvent in the solvent system is 5wt% to 20wt%.

4. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of secondary copolymerized PPTA to prepolymer containing flexible segments is 0.1 to 10.

5. The preparation method according to claim 2, characterized in that, In step (1), the temperature for low-temperature solution polycondensation is -15℃ to 15℃, and the time is 10 min to 60 min; the temperature for secondary copolymerization is 5℃ to 20℃, and the time is 30 min to 90 min.

6. The preparation method according to claim 2, characterized in that, In step (2), the coagulation bath is a non-solvent-solvent mixed solution of 0 wt% to 80 wt%; wherein the non-solvent is one or more non-polar solvents; wherein the solvent is one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylacetamide, and benzimidazole ionic liquids. In step (2), the diameter of the PPTA precipitated fiber containing flexible segments is 50-800 μm.

7. The preparation method according to claim 2, characterized in that, In step (3), the hot pressing temperature is 200-350℃, the hot pressing pressure is 5-15MPa, and the hot pressing time is 10-50min.

8. The application of the flexible segment poly(p-phenylene terephthalamide) (PPTA) fiber paper as described in claim 1 in the fields of insulating materials and honeycomb core materials.

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