Diamine monomer and preparation method thereof, polyimide material and preparation method and application thereof

Abstract

The invention provides a diamine monomer and a preparation method thereof, and a polyimide material and a preparation method and application thereof. The structural formula of the diamine monomer is shown as a formula I, and the diamine monomer is a functional diamine monomer containing a beta-hydroxy ketone structure and has excellent ultraviolet absorption performance. A functional diamine monomer A containing a beta-hydroxy ketone structure, a diamine monomer B with atomic oxygen resistance and a diamine monomer C are matched to be used as diamine monomers, the diamine monomers and a dianhydride monomer are polymerized together, and the polyimide material is obtained after imidization and other process treatment. The ultraviolet radiation resistance and the atomic oxygen radiation resistance are excellent. Tests show that after the polyimide fiber prepared by the method is irradiated by ultraviolet (the wavelength range is 280-400nm and the irradiation intensity is 15W / m < 2 >) for 2000h and is irradiated by atomic oxygen of 5 * 10 < 20 > atoms * cm <-2 >, the breaking strength retention rate is more than 80%, and the maximum breaking strength retention rate is up to 95.4%.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and in particular relates to a diamine monomer and a preparation method thereof, a polyimide material and a preparation method and application thereof. Background Art

[0002] Polyimide fiber has excellent properties such as high strength and modulus, high and low temperature resistance, chemical resistance, flame retardancy, low thermal expansion coefficient, small creep, and radiation resistance, and is widely used in high-tech fields such as aerospace, weapons and equipment, and transportation. Studies have reported that when polyimide fiber is used in a low-Earth orbit environment, in addition to being affected by high vacuum, high-energy charged particles, space debris, and high and low temperature cycles, it will also be eroded by ultraviolet rays and atomic oxygen radiation, resulting in a decrease in the comprehensive performance of the fiber and affecting the service life of the spacecraft.

[0003] At present, the research and development of polyimide materials resistant to ultraviolet radiation and atomic oxygen radiation mainly include surface strengthening method and matrix strengthening method. Among them, the surface strengthening method refers to the formation of a protective layer on the surface of the polyimide material by surface coating or deposition. The matrix strengthening method mainly refers to the introduction of radiation-resistant groups into the polyimide matrix by blending, copolymerization and other methods. Patent CN103255501B adds a light stabilizer to the polyamic acid spinning solution, and obtains a polyimide fiber resistant to ultraviolet radiation after spinning, imidization and post-treatment. Patent CN105671680A adds polysilsesquioxane to the polyamic acid spinning solution, and obtains a polyimide fiber resistant to atomic oxygen after spinning. Patent CN110698670A introduces carborane into the polyimide molecular chain through copolymerization, and the obtained polyimide film has atomic oxygen resistance.

[0004] However, there are few reports on the preparation of polyimide fibers with both ultraviolet radiation resistance and atomic oxygen resistance by copolymerization. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a diamine monomer and a preparation method thereof, a polyimide material and a preparation method and application thereof. The polyimide material has excellent ultraviolet radiation resistance and atomic oxygen radiation resistance.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a diamine monomer as shown in Formula I:

[0008] Formula I;

[0009] Wherein, R is selected from substituted or unsubstituted C1~C6 alkyl.

[0010] Preferably, R is selected from substituted or unsubstituted C1~C4 alkyl;

[0011] More preferably, the R is selected from one of methyl, ethyl, isopropyl or tert-butyl.

[0012] The diamine monomer is selected from any one of the following formulas I-1 to I-12:

[0013] .

[0014] In a second aspect, the present invention provides a method for preparing a diamine monomer, comprising:

[0015] S1: subjecting the nitrobenzoyl compound represented by formula a to a Friedel-Crafts acylation reaction with the p-alkylanisole represented by formula b to obtain an intermediate;

[0016] Formula a; Formula b;

[0017] Wherein, X is selected from -OH, -Cl, -Br, -I, -OAc; R is selected from Me, Et, i Pr, t Bu;

[0018] S2: Demethylating the intermediate under acidic conditions to obtain a mononitro compound, and then subjecting the mononitro compound to nitration and reduction to obtain a diamine monomer as shown in Formula I.

[0019] Preferably, the molar ratio of the nitrobenzoyl compound to p-alkylanisole is (1.0-1.5):1.

[0020] Preferably, the temperature of the Friedel-Crafts acylation reaction is -10 to 40 o C.

[0021] Preferably, the temperature of the nitration reaction is -20 to 50 o C.

[0022] Preferably, the reduction reaction temperature is room temperature to 100 o C.

[0023] In the present invention, the room temperature refers to a temperature of "15-30 o C", preferably 25 o C.

[0024] In a third aspect, the present invention provides a polyimide material, which is prepared from a dianhydride monomer and a diamine monomer;

[0025] The diamine monomers include diamine monomer A, diamine monomer B and diamine monomer C;

[0026] The diamine monomer A is any one or more of the diamine monomers according to claim 1 or the diamine monomers prepared by the preparation method according to claim 2 or 3;

[0027] The diamine monomer B is selected from any one or more of the following formulas II-1 to II-9:

[0028] ;

[0029] The diamine monomer C is selected from any one or more of the following formulas III-1 to III-19:

[0030] .

[0031] Preferably, the dianhydride monomer is selected from any one or more of the following formulae:

[0032] .

[0033] Preferably, the molar ratio of the dianhydride monomer to the diamine monomer is 1:(0.9-1.5).

[0034] Preferably, the molar ratio of the diamine monomer A, the diamine monomer B and the diamine monomer C is: (0.05-0.5): (0.05-0.6): (0.2-1).

[0035] Preferably, the polyimide material comprises polyimide fibers.

[0036] In a fourth aspect, the present invention provides a method for preparing the above-mentioned polyimide material, comprising:

[0037] After polymerizing the dianhydride monomer and the diamine monomer in a solvent, a polyamic acid intermediate is obtained;

[0038] The polyamic acid intermediate is imidized to obtain a polyimide material.

[0039] It should be noted that after obtaining the polyamic acid intermediate, the polyamic acid intermediate can be pretreated according to the presentation form of the final polyimide material (such as polyimide fiber, polyimide film, polyimide resin, polyimide foam, etc.) and then subjected to imidization treatment.

[0040] For example, preferably, the polyamic acid intermediate is subjected to spinning treatment, and then to imidization and heat drawing treatment to obtain polyimide fibers.

[0041] or

[0042] Preferably, the polyamic acid intermediate is subjected to film casting and solvent removal treatment, and then imidization treatment to obtain a polyimide film.

[0043] In a fifth aspect, the present invention provides an application of the polyimide material involved in the above technical solution in the preparation of aerospace vehicles.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a diamine monomer as shown in formula I, wherein the hydrogen and carbonyl oxygen of the ortho-hydroxyl group can form an intramolecular hydrogen bond, and the intramolecular hydrogen bond of the diamine monomer is destroyed after absorbing ultraviolet light, and becomes an enol structure, which has poor structural stability and returns to the original structure after releasing heat. Therefore, the introduction of the β-hydroxy ketone structure into the polyimide molecular chain can effectively inhibit or delay the damage of ultraviolet light to the polyimide material. The present invention uses a functional diamine monomer A containing a β-hydroxy ketone structure, a diamine monomer B having atomic oxygen resistance, and a diamine monomer C, and the three are used in combination as diamine monomers, and are polymerized together with a dianhydride monomer, and the polyimide material (such as polyimide fiber) obtained after processing by imidization and other processing techniques has excellent ultraviolet radiation resistance and atomic oxygen radiation resistance.

[0046] After testing, the polyimide fiber prepared by the present invention was subjected to ultraviolet (wavelength range 280~400nm, irradiation intensity 15W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, its strength retention rate is above 80%, and can reach up to 95.4%.

[0047] In addition, the preparation method of the polyimide material provided by the present invention has simple process, high process controllability, and is easy to industrialize. If the polyimide fiber is prepared, it can be applied to various spinning molding methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of (2-methoxy-5-methylphenyl) (4-nitrophenyl) ketone in Preparation Example 2;

[0049] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of (2-hydroxy-5-methylphenyl) (4-nitrophenyl) ketone in Preparation Example 2;

[0050] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of (2-hydroxy-5-methyl-3-nitrophenyl) (4-nitrophenyl)methanone in Preparation Example 2;

[0051] Figure 4 is the hydrogen nuclear magnetic resonance spectrum of (3-amino-2-hydroxy-5-methylphenyl) (4-aminophenyl)methanone in Preparation Example 2;

[0052] Figure 5 is the carbon NMR spectrum of (3-amino-2-hydroxy-5-methylphenyl) (4-aminophenyl)methanone in Preparation Example 2;

[0053] Figure 6 This is the high-resolution mass spectrum of (3-amino-2-hydroxy-5-methylphenyl) (4-aminophenyl)methanone in Preparation Example 2. DETAILED DESCRIPTION

[0054] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The existing technologies all obtain polyimide fibers with single atomic oxygen resistance or single ultraviolet radiation resistance. When used in the low-Earth orbit environment, polyimide fibers will be corroded by ultraviolet rays and atomic oxygen at the same time, and even form a composite effect, which will affect the comprehensive performance of the polyimide fibers and affect the normal service of the spacecraft.

[0056] In view of this, in order to overcome the shortcomings of the above method, the present invention introduces a diamine monomer A with ultraviolet absorption function and a diamine monomer B with atomic oxygen resistance function into the main chain of the polyimide macromolecule through a copolymerization reaction to prepare a polyimide material with both ultraviolet radiation resistance and atomic oxygen resistance.

[0057] First, the present invention provides a diamine monomer as shown in Formula I:

[0058] Formula I;

[0059] Wherein, R is selected from substituted or unsubstituted C1~C6 alkyl.

[0060] In some embodiments of the present invention, the diamine monomer has a structure as shown in Formula I, and R is preferably a substituted or unsubstituted C1-C4 alkyl group.

[0061] In some preferred embodiments of the present invention, the diamine monomer has a structure as shown in Formula I, and R is preferably one of methyl, ethyl, isopropyl or tert-butyl.

[0062] In some specific embodiments of the present invention, the diamine monomer is selected from any one or more of the following formulas I-1 to I-12:

[0063] .

[0064] The diamine monomer shown in the above formula I provided by the present invention has a β-hydroxyketone structure, and therefore has excellent ultraviolet absorption performance.

[0065] The present invention also provides a method for preparing the above diamine monomer, comprising:

[0066] S1: subjecting the nitrobenzoyl compound represented by formula a to a Friedel-Crafts acylation reaction with the p-alkylanisole represented by formula b to obtain an intermediate;

[0067] Formula a; Formula b;

[0068] Wherein, X is selected from -OH, -Cl, -Br, -I, -OAc; R is selected from Me, Et, i Pr, t Bu;

[0069] S2: Demethylating the intermediate under acidic conditions to obtain a mononitro compound, and then subjecting the mononitro compound to nitration and reduction to obtain a diamine monomer as shown in Formula I.

[0070] According to the present invention, firstly, a nitrobenzoyl compound and p-alkylanisole undergo Friedel-Crafts acylation reaction to obtain an intermediate. The nitrobenzoyl compound is selected from any one or more of 4-nitrobenzoic acid, 4-nitrobenzoyl chloride, 4-nitrobenzoyl bromide, 4-nitrobenzoyl iodide, a mixed anhydride prepared from 4-nitrobenzoic acid and other acid anhydrides, 3-nitrobenzoic acid, 3-nitrobenzoyl chloride, 3-nitrobenzoyl bromide, 3-nitrobenzoyl iodide or a mixed anhydride prepared from 3-nitrobenzoic acid and other acid anhydrides, 2-nitrobenzoic acid, 2-nitrobenzoyl chloride, 2-nitrobenzoyl bromide, 2-nitrobenzoyl iodide, and a mixed anhydride prepared from 2-nitrobenzoic acid and other acid anhydrides. In the present invention, the Friedel-Crafts acylation reaction is preferably carried out in the presence of a catalyst, and the catalyst can be selected from any one or more of aluminum trifluoride, aluminum trichloride, aluminum tribromide, aluminum triiodide, lanthanum trifluoromethanesulfonate (Ln(OTf)3), sulfuric acid, phosphoric acid, ferric chloride, zinc dichloride or polyphosphoric acid.

[0071] In some embodiments of the present invention, the molar ratio of the nitrobenzoyl compound to the p-alkylanisole is preferably (1.0-1.5):1, more preferably (1.2-1.4):1, in the presence of a catalyst at -10-40 °C. o C, preferably -10~10 o C, a Friedel-Crafts acylation reaction occurs to obtain an intermediate.

[0072] After obtaining the intermediate, according to the present invention, the intermediate is demethylated under acidic conditions to obtain a mononitro compound. The reagents used in the acidic conditions include: any one or more of boron tribromide, boron trichloride, 48% hydrobromic acid aqueous solution, pyridine hydrochloride or magnesium iodide ether complex. In the present invention, the demethylation protection is preferably carried out in a solvent, and the solvent is selected from any one or more of dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, toluene or xylene, preferably dichloromethane and / or chloroform.

[0073] After obtaining the mononitro compound, according to the present invention, the mononitro compound is subjected to a nitration reaction and a reduction reaction in sequence to obtain a diamine monomer shown in Formula I. In the present invention, the reagent used in the nitration reaction is selected from any one or more of a concentrated nitric acid / concentrated sulfuric acid combination, a concentrated nitric acid / acetic acid combination, a concentrated nitric acid / acetic anhydride combination, a concentrated nitric acid / phosphorus pentoxide combination, a nitrogen pentoxide / sulfuric acid combination or a nitrogen pentoxide / acetic acid combination, preferably a concentrated nitric acid / concentrated sulfuric acid combination, wherein the molar ratio of concentrated nitric acid, concentrated sulfuric acid and the mononitro compound is (1.2-2.0):(0.5-1.0):1.0. In some embodiments of the present invention, the mononitro compound is preferably subjected to the presence of the above reagents at -20-50 °C. o C, preferably -10~30 o C undergoes nitrification reaction.

[0074] In the present invention, the reduction reaction is preferably carried out in the presence of a catalyst, and the catalyst is selected from a combination of a catalytic component and hydrogen (i.e., specifically: any one of Raney nickel, palladium / carbon, platinum / carbon, rhodium / carbon or ruthenium / carbon and hydrogen), stannous chloride, titanium chloride, iron / acetic acid, zinc / acetic acid, sodium sulfide, sodium thiosulfate, lithium aluminum hydride, and one or more of sodium borohydride.

[0075] In some embodiments of the present invention, the product obtained after the nitration reaction is preferably heated at room temperature to 100°C in the presence of the above catalyst. o C undergoes a reduction reaction to obtain a diamine monomer shown in formula I.

[0076] It can be seen that the preparation method of the diamine monomer represented by the above formula I provided by the present invention is simple, convenient and easy to implement.

[0077] The present invention also provides a polyimide material (such as polyimide fiber), which is prepared from a dianhydride monomer and a diamine monomer. The dianhydride monomer includes but is not limited to any one or more of the following formulas:

[0078] ;

[0079] The diamine monomers include diamine monomer A, diamine monomer B and diamine monomer C;

[0080] The diamine monomer A is any one or more of the diamine monomers shown in the above formula I;

[0081] The diamine monomer B is selected from any one or more of the following formulas II-1 to II-9:

[0082] ;

[0083] The diamine monomer C is selected from any one or more of the following formulas III-1 to III-19:

[0084] .

[0085] It should be noted that the molar ratio of the dianhydride monomer to the diamine monomer is 1:(0.9-1.5), preferably 1:(1.0-1.4), and more preferably 1:(1.2-1.3). The molar ratio of the diamine monomer A, diamine monomer B and diamine monomer C is: (0.05-0.5):(0.05-0.6):(0.2-1).

[0086] In summary, the present invention introduces a diamine monomer A containing a β-hydroxyketone structure (i.e., having excellent ultraviolet absorption performance), a diamine monomer B (containing phosphorus) having excellent resistance to atomic oxygen radiation, and other diamine monomers C into the main chain of polyimide through a copolymerization reaction with a dianhydride monomer, thereby preparing a polyimide material that is resistant to both ultraviolet radiation and atomic oxygen radiation.

[0087] The present invention also provides a method for preparing the above-mentioned polyimide material, which comprises:

[0088] After polymerizing the dianhydride monomer and the diamine monomer in a solvent, a polyamic acid intermediate is obtained;

[0089] The polyamic acid intermediate is subjected to imidization and other processing to obtain a polyimide material.

[0090] According to the present invention, firstly, the dianhydride monomer and the diamine monomer are polymerized in a solvent at a molar ratio of 1:(0.9~1.5) to obtain a polyamic acid intermediate. The selection of the dianhydride monomer and the diamine monomer is as described in the relevant content of the above technical scheme, which will not be repeated here. The solvent is preferably a polar aprotic solvent, and the polar aprotic solvent can be specifically selected from any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone. In some embodiments of the present invention, the dianhydride monomer and the diamine monomer are in a solvent at -20~50 o C polymerization for 4 to 60 hours, preferably at -10 to 30 oC polymerization for 10 to 40 hours. In the present invention, the obtained polyamic acid intermediate exists in the form of a solution, preferably the concentration of the polyamic acid intermediate is 5 to 40 wt%, more preferably 10 to 30 wt%; if the concentration is too low, the polymer solution is difficult to form fibers and the spinning efficiency is low; if the concentration is too high, the apparent viscosity of the polymer solution is too large, and the solution is in a gel state, which also leads to the inability to spin.

[0091] After obtaining the polyamic acid intermediate, it is preferably subjected to imidization treatment. In some embodiments of the present invention, the imidization treatment is preferably carried out by gradient temperature rise heat treatment or constant temperature heat treatment. The temperature of the gradient temperature rise heat treatment is preferably 50 to 500 °C. o C, more preferably 80 to 450 o C; the heating rate is preferably 1~30 o C / min, more preferably 5 to 20 o C / min. The temperature of the constant temperature treatment is 300~500 o C, preferably 350~400 o C; the treatment time is 10 to 50 min. In the present invention, the imidization treatment is preferably carried out under an inert gas atmosphere, and the inert gas atmosphere is preferably a nitrogen or argon atmosphere.

[0092] It should be noted that if the polyimide material is a polyimide fiber, the present invention is preferably subjected to a spinning treatment after obtaining a polyamic acid intermediate, and then subjected to imidization and heat drawing treatment. In some embodiments of the present invention, the polyamic acid intermediate is first filtered and vacuum deaerated to obtain a spinning solution. Then, a spinning forming process is adopted to spin to obtain a polyamic acid fiber. Then, the polyamic acid fiber is further subjected to imidization and heat drawing treatment to obtain a polyimide fiber with excellent performance.

[0093] The present invention has no special limitation on the spinning method, which may be wet spinning, dry spinning or dry-jet-wet spinning, preferably wet spinning or dry-jet-wet spinning.

[0094] The dry-jet wet spinning process can be carried out as follows: the obtained spinning solution is extruded from the spinneret through a metering pump, passes through an air layer and enters a coagulation bath for forming, and then is drawn and washed, and dried by a hot roller or a tunnel to obtain polyamic acid fibers. The coagulation bath used is preferably a mixture of one of ethanol, ethylene glycol, butanol, acetone and butanone with water, or a mixture of any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone with water; the dry environment is preferably air, nitrogen, argon or other inert gases; the height of the air layer is preferably 3~80 mm, preferably 5~60 mm; the aperture of the spinneret is preferably Φ 0.06~Φ0.5 mm, more preferably Φ0.1~Φ0.3mm, the number of holes is preferably 20~5000 holes, more preferably 100~3000 holes; the spray-to-pulling ratio is preferably 1.5~7.0 times, more preferably 2.0~5.0 times; the speed is preferably 10~100 m / min, more preferably 20~80 m / min.

[0095] The wet spinning process is carried out as follows: the obtained spinning solution is extruded from the spinneret through a metering pump, directly enters a coagulation bath for forming, and then is drawn, washed, and dried by a hot roller or a hot tunnel to obtain polyamic acid fibers. The coagulation bath used is preferably a mixture of one of ethanol, ethylene glycol, butanol, acetone and butanone and water, or a mixture of one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone and water; the drying environment is preferably air, nitrogen, argon or other inert gases; the spinneret aperture is preferably Φ 0.04~Φ 0.15 mm, more preferably Φ 0.06~Φ0.1 mm, the number of holes is preferably 30~8000 holes, more preferably 100~5000 holes; the spray-to-draw ratio is preferably 1.1~6.0 times, more preferably 2.0~5.0 times; the speed is 5~80 m / min, more preferably 10~60 m / min.

[0096] The dry spinning process is carried out as follows: the obtained spinning solution is extruded from the spinneret through a metering pump, directly passes through a long hot air channel, removes the solvent and is formed, and at the same time, is stretched and thinned under the action of winding tension to obtain polyamic acid fibers.

[0097] In some embodiments of the present invention, after the polyamic acid fiber is obtained and imidized, it is preferably subjected to a heat drawing treatment to obtain a polyimide fiber with excellent performance. The present invention has no particular limitation on the heat drawing method, which is well known to those skilled in the art. In the present invention, the temperature of the heat drawing is 350 to 600 °C. o C, preferably 400~500 oC; the thermal stretching ratio is 1.0 to 5.0 times, preferably 2.0 to 4.0 times; the thermal stretching environment is preferably an inert gas atmosphere, more preferably a nitrogen or argon atmosphere.

[0098] If the polyimide material is a polyimide film, after obtaining the polyamic acid intermediate, the present invention preferably performs film casting and solvent removal treatment on it, and then performs imidization treatment.

[0099] The preparation method of the polyimide material provided by the present invention has simple process, high process controllability and is easy to industrialize. If the polyimide fiber is prepared, it can be applicable to various spinning molding methods.

[0100] After testing, the polyimide fiber prepared by the present invention was subjected to ultraviolet (wavelength range 280~400nm, irradiation intensity 15W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, its strength retention rate is above 80%, and can reach up to 95.4%.

[0101] Based on this, the present invention also provides an application of a polyimide material in the preparation of an aerospace vehicle, which can meet the material requirements of the aerospace vehicle for resistance to ultraviolet radiation and atomic oxygen radiation.

[0102] In order to further illustrate the present invention, the following examples are provided for detailed description. The experimental raw materials used in the following examples of the present invention are all common commercially available products.

[0103] Preparation Example 1

[0104] I-1 Synthesis of monomer ((3-amino-2-hydroxy-5-methylphenyl)(3-aminophenyl)methanone)

[0105] (1) Preparation of (2-methoxy-5-methylphenyl) (3-nitrophenyl) ketone

[0106] 4-Methylanisole (61.08 g, 0.50 mol), aluminum chloride (80.00 g, 0.60 mol), dichloromethane (1000 ml) and 3-nitrobenzoyl chloride (102.08 g, 0.55 mol) were added to the reaction flask in sequence at 20 o C for 16 hours. Then, the reaction system was slowly added to ice-hydrochloric acid, and the organic phase and the aqueous phase were separated and extracted, the aqueous phase was extracted with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a crude product, which was recrystallized to obtain (2-methoxy-5-methylphenyl) (3-nitrophenyl) ketone with a yield of 93%. 1H NMR (500 MHz, DMSO-d6) δ 8.43 (t, J=1.5 Hz, 1H) , 8.42 (d, J=1.5 Hz, 1H), , 8.04 (d, J=7.5Hz, 1H), 7.79 (t, J=7.5 Hz, 1H), 7.62(s,1H), 7.36 (d, J = 4.0 Hz, 1H), 7.03 (d, J = 12.0 Hz, 1H), 3.66 (s, 3H), 2.44 (s, 3H). .

[0107] (2) Preparation of (2-hydroxy-5-methylphenyl) (3-nitrophenyl) ketone

[0108] (2-methoxy-5-methylphenyl)(3-nitrophenyl)methanone (135.63 g, 0.50 mol), acetic acid (1200 g, 20 mol) and 40% hydrobromic acid solution (200 g, 2.50 mol) were added to the reaction flask in sequence, and the reaction system was heated to 100 o C for 10 hours. According to TLC detection, the raw material has completely disappeared and the reaction is over. The hydrobromic acid and acetic acid in the reaction system are recovered, dichloromethane and water are added to the residue, and a saturated sodium carbonate solution is added under stirring for neutralization, and the mixture is transferred to a separatory funnel, and the organic phase is extracted, dried with anhydrous sodium sulfate, filtered, and concentrated to obtain a crude product. The crude product is recrystallized to obtain (2-hydroxy-5-methylphenyl) (3-nitrophenyl) ketone with a yield of 91%. 1 H NMR (500 MHz, DMSO-d6) δ10.48 (brs, 1H), 8.45 (d, J = 7.5 Hz, 1H), 8.44 (s, 1H), 8.11 (d, J = 7.5 Hz, 1H), 7.81 (t, J=7.5 Hz, 1H), 7.43 (s, 1H), 7.18 (dd, J = 7.5 Hz, 1.5 Hz, 1H), 6.91 (d, J = 7.5 Hz, 1H), 1.80 (s, 3H).

[0109] (3) Preparation of (2-hydroxy-5-methyl-3-nitrophenyl) (3-nitrophenyl) ketone

[0110] (2-Hydroxy-5-methylphenyl)(4-nitrophenyl)methanone (151.12 g, 0.50 mol), acetic acid (467 ml, 8.17 mol), concentrated sulfuric acid (19.2 ml, 0.35 mol) and dichloromethane (500 ml) were added to a reaction flask, and an acetic acid solution of concentrated nitric acid (72.67 g, 0.75 mol) was slowly added dropwise to the reaction system. The reaction system was then continued to react at room temperature for 3 hours. The reaction was terminated after the raw material completely disappeared as detected by TLC. The reaction mixture was filtered, washed with saturated sodium bicarbonate, saturated sodium chloride and distilled water to obtain a crude product, which was recrystallized to obtain (2-hydroxy-5-methyl-3-nitrophenyl)(3-nitrophenyl)methanone with a yield of 92%. 1 H NMR (500 MHz, DMSO-d6) δ 10.49 (s, 1H),8.45 (d J = 1.5 Hz, 1H), 8.44 (t, J = 1.0 Hz, 1H), 8.20 (d J = 1.5 Hz, 1H),8.05 (d, J = 7.5 Hz, 1H), 7.87 (d J = 1.5 Hz, 1H), 7.80 (t, J = 7.5 Hz, 1H), 2.42 (s, 3H).

[0111] (4) Preparation of (3-amino-2-hydroxy-5-methylphenyl) (3-aminophenyl)methanone

[0112] (2-Hydroxy-5-methyl-3-nitrophenyl)(3-nitrophenyl)methanone (60.44 g, 0.20 mol), stannous chloride dihydrate (315.88 g, 1.40 mol) and 400 ml of ethyl acetate were added to the reaction flask in sequence, and the reaction system was heated to 70 o C for 3 hours, and the reaction was terminated after the raw material completely disappeared as detected by TLC. After the reaction system was cooled to room temperature, it was transferred to a saturated sodium bicarbonate solution for neutralization, the mixture was extracted with ethyl acetate, the organic phases were combined and dried over anhydrous sodium sulfate, and the solvent was removed by concentration to obtain a crude product, which was recrystallized to obtain (3-amino-2-hydroxy-5-methylphenyl) (3-aminophenyl) ketone with a yield of 87%. 1H NMR (500 MHz, DMSO-d6) δ 10.89 (s, 1H), 7.22 (d, J =7.5 Hz, 1H), 7.11 (d J = 1.5 Hz, 1H), 7.10 (d J = 3.5 Hz, 1H), 6.88 (d J =1.5 Hz, 1H), 6.83 (d J = 1.5 Hz, 1H), 6.78 (d, J = 7.5 Hz, 1H), 5.23 (s, 2H), 5.01 (s, 2H), 2.40 (s, 3H). 13 C NMR (125 MHz, DMSO-d6) δ 197.23, 148.43,148.29, 137.53, 137.39, 131.20, 129.27, 125.32, 123.46, 122.36, 120.92,118.95, 115.02, 21.81. Theoretical elemental analysis, calculated forC 14 H 14 HRMS (ESI) calcd for C 14 H 14 N2O2 [M + H + ] 243.1134, found 243.1131.

[0113] Preparation Example 2

[0114] Synthesis of I-5 monomer ((3-amino-2-hydroxy-5-methylphenyl)(4-aminophenyl)methanone)

[0115] (1) Preparation of (2-methoxy-5-methylphenyl) (4-nitrophenyl) ketone

[0116] 4-Methylanisole (73.3 g, 0.60 mol), aluminum chloride (96.0 g, 0.72 mol), dichloromethane (1200 ml) and 4-nitrobenzoyl chloride (122.5 g, 0.66 mol) were added to the reaction flask in sequence at 20 oC for 15 hours. Then the reaction system was slowly added to an ice-water bath-hydrochloric acid, and the organic phase and the aqueous phase were separated and extracted. The aqueous phase was extracted with dichloromethane, and the organic phase was dried with anhydrous magnesium sulfate, filtered and concentrated to obtain a crude product. The crude product was recrystallized to obtain (2-methoxy-5-methylphenyl) (4-nitrophenyl) ketone with a yield of 98%. Its H NMR spectrum is shown in Figure 1 As shown, 1 H NMR (400 MHz, DMSO-d6) δ 8.33 (d, J = 12.0 Hz, 2H), 7.89 (d, J =12.0 Hz, 2H ), 7.42 (dd, J = 8.0, 4.0 Hz, 1H), 7.24 (d, J = 4.0 Hz, 1H), 7.12 (d, J = 12.0 Hz, 1H), 3.60 (s, 3H), 2.30 (s, 3H).

[0117] (2) Preparation of (2-hydroxy-5-methylphenyl) (4-nitrophenyl) ketone

[0118] (2-methoxy-5-methylphenyl)(4-nitrophenyl)methanone (162.8 g, 0.60 mol), acetic acid (1440 g, 24 mol) and 40% hydrobromic acid solution (240 g, 3.0 mol) were added to the reaction flask in sequence, and the reaction system was heated to 100 o C for 10 hours. According to TLC detection, the raw material has completely disappeared and the reaction is over. Recover the hydrobromic acid and acetic acid in the reaction system, add dichloromethane and water to the residue, add saturated sodium carbonate solution to neutralize under stirring, transfer the mixture to a separatory funnel, extract and separate, dry the organic phase with anhydrous sodium sulfate, filter and concentrate to obtain a crude product, and the crude product is recrystallized to obtain (2-hydroxy-5-methylphenyl) (4-nitrophenyl) ketone with a yield of 93%. Its hydrogen nuclear magnetic resonance spectrum is as follows Figure 2 As shown, 1 H NMR (400 MHz, DMSO-d6) δ 10.23 (s, 1H), 8.34 (d, J = 8.4 Hz, 2H), 7.91 (d,J = 8.8 Hz, 2H), 7.31 (d, J = 8.4 Hz, 1H), 7.21 (s, 1H), 6.90 (d, J = 8.4 Hz,1H), 2.25 (s, 3H).

[0119] (3) Preparation of (2-hydroxy-5-methyl-3-nitrophenyl) (4-nitrophenyl) ketone

[0120] (2-Hydroxy-5-methylphenyl) (4-nitrophenyl) ketone (154.35 g, 0.60 mol), acetic acid (560 ml, 9.8 mol), concentrated sulfuric acid (23 ml, 0.42 mol) and dichloromethane (600 ml) were added to the reaction bottle, and the acetic acid solution of concentrated nitric acid (87.2 g, 0.90 mol) was slowly added to the reaction system. Then the reaction system continued to react at room temperature for 3 hours. After TLC detection, the reaction was terminated after the raw material completely disappeared. The reaction mixture was filtered, washed with saturated sodium bicarbonate, saturated sodium chloride and distilled water to obtain a crude product. The crude product was recrystallized to obtain (2-hydroxy-5-methyl-3-nitrophenyl) (4-nitrophenyl) ketone with a yield of 90%. Its hydrogen nuclear magnetic resonance spectrum is as follows Figure 3 As shown, 1 H NMR (400 MHz, DMSO-d6) δ 10.78 (s, 1H), 8.36 (d, J = 6.8, 2.0 Hz, 2H), 8.06 (dd, J = 2.0, 0.8Hz, 1H), 8.00 (d, J = 6.8 Hz, 2H), 7.63 (dd, J = 2.0, 0.4 Hz, 0H), 2.35 (s, 3H).

[0121] (4) Preparation of (3-amino-2-hydroxy-5-methylphenyl) (4-aminophenyl)methanone

[0122] (2-Hydroxy-5-methyl-3-nitrophenyl)(4-nitrophenyl)methanone (30.22 g, 0.10 mol), stannous chloride dihydrate (157.94 g, 0.70 mol) and 400 ml of ethyl acetate were added to the reaction flask in sequence, and the reaction system was heated to 70 o C for 3 hours. After TLC detection, the reaction is terminated when the raw material disappears completely. After the reaction system is cooled to room temperature, it is transferred to a saturated sodium bicarbonate solution for neutralization. The mixture is extracted with ethyl acetate, the organic phases are combined and dried over anhydrous sodium sulfate, and the solvent is concentrated to obtain a crude product. The crude product is recrystallized to obtain (3-amino-2-hydroxy-5-methylphenyl) (4-aminophenyl) ketone with a yield of 91%. Its hydrogen nuclear magnetic resonance spectrum is shown in Figure 4 As shown, 1H NMR (400 MHz, DMSO-d6) δ10.93 (s, 1H), 7.50 (d, J = 8.4 Hz, 1H), 6.66 (d, J = 1.6 Hz, 1H), 6.61 (d, J= 6.8 Hz, 2H), 6.53 (d, J = 2.0 Hz, 1H), 6.12 (s, 2H), 4.82 (s, 2H), 2.14 (s,3H). Its carbon NMR spectrum is shown in the figure below. Figure 5 As shown, 13 C NMR (101 MHz, DMSO-d6) δ 197.49, 153.56,145.06, 137.63, 132.40, 127.18, 124.44, 120.74, 118.90, 118.55, 112.46,20.60. Its high resolution mass spectrum is shown in Figure 6 As shown, Theoretical elemental analysis, calculated for C 14 H 14 HRMS (ESI) calcd for C 14 H 14 N2O2 [M + H + ] 243.1134, found 243.1131.

[0123] Preparation Example 3

[0124] Synthesis of I-9 monomer ((3-amino-2-hydroxy-5-methylphenyl)(2-aminophenyl)methanone)

[0125] (1) Preparation of (2-methoxy-5-methylphenyl) (2-nitrophenyl) ketone

[0126] 4-Methylanisole (48.86 g, 0.40 mol), aluminum chloride (64.00 g, 0.48 mol), dichloromethane (800 ml) and 2-nitrobenzoyl chloride (81.67 g, 0.44 mol) were added to the reaction flask in sequence at 20 oC for 15 hours. Then, the reaction system was slowly added to an ice-water bath-hydrochloric acid, and the organic phase and the aqueous phase were separated and extracted, the aqueous phase was extracted with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated to obtain a crude product, which was recrystallized to obtain (2-methoxy-5-methylphenyl) (2-nitrophenyl) ketone with a yield of 94%. 1 H NMR (00 MHz, DMSO-d6) δ 8.28 (d, J = 6.0 Hz, 1H), 8.09 (t, J = 6.0 Hz, 1H), 7.92 (d, J =6.0 Hz, 1H), 7.86 (m, 1H), 7.70 (s, 1H), 7.41 (d, J = 0.8 Hz, 1H), 7.12 (d, J= 6.0 Hz, 1H), 3.68 (s, 3H), 2.47 (s, 3H).

[0127] (2) Preparation of (2-hydroxy-5-methylphenyl) (2-nitrophenyl) ketone

[0128] (2-Methoxy-5-methylphenyl)(2-nitrophenyl)methanone (108.5 g, 0.40 mol), acetic acid (960 g, 16 mol) and 40% hydrobromic acid solution (160 g, 2.00 mol) were added to the reaction flask in sequence, and the reaction system was heated to 100 o C for 10 hours. According to TLC detection, the raw material has completely disappeared and the reaction is over. The hydrobromic acid and acetic acid in the reaction system are recovered, dichloromethane and water are added to the residue, and a saturated sodium carbonate solution is added under stirring for neutralization, and the mixture is transferred to a separatory funnel, and the organic phase is extracted, dried with anhydrous sodium sulfate, filtered, and concentrated to obtain a crude product. The crude product is recrystallized to obtain (2-hydroxy-5-methylphenyl) (2-nitrophenyl) ketone with a yield of 92%. 1 H NMR (400 MHz, DMSO-d6) δ10.34 (s, 1H), 8.35 (d, J = 0.8 Hz, 1H), 8.10 (m, 1H), 7.95 (d, J = 4.0 Hz,1H), 7.89 (m, 1H), 7.42 (s, 1H), 7.23 (d, J = 8.0 Hz, 1H), 6.93 (d, J = 4.0Hz, 1H), 2.42 (s, 1H).

[0129] (3) Preparation of (2-hydroxy-5-methyl-3-nitrophenyl) (2-nitrophenyl) ketone

[0130] (2-Hydroxy-5-methylphenyl)(4-nitrophenyl)methanone (102.9 g, 0.40 mol), acetic acid (373 ml, 6.5 mol), concentrated sulfuric acid (15.3 ml, 0.28 mol) and dichloromethane (400 ml) were added to a reaction flask, and a solution of concentrated nitric acid (58.1 g, 0.60 mol) in acetic acid was slowly added dropwise to the reaction system. The reaction system was then continued to react for 3 hours at room temperature. The reaction was terminated after the raw material completely disappeared as detected by TLC. The reaction mixture was filtered, washed with saturated sodium bicarbonate, saturated sodium chloride and distilled water to obtain a crude product, which was recrystallized to obtain (2-hydroxy-5-methyl-3-nitrophenyl)(2-nitrophenyl)methanone with a yield of 89%. 1 H NMR (400 MHz, DMSO-d6) δ 10.42 (s, 1H), 8.33(d, J = 8.0 Hz, 1H), 8.16 (s, 1H), 8.09 (m, 1H), 7.98 (d, J = 8.0, 1H), 7.92(s, 1H), 7.88 (m, 1H), 2.42 (s, 3H).

[0131] (4) Preparation of (3-amino-2-hydroxy-5-methylphenyl) (2-aminophenyl)methanone

[0132] (2-Hydroxy-5-methyl-3-nitrophenyl)(2-nitrophenyl)methanone (30.22 g, 0.10 mol), stannous chloride dihydrate (157.94 g, 0.70 mol) and 400 ml of ethyl acetate were added to the reaction flask in sequence, and the reaction system was heated to 70 o C for 3 hours, and the reaction was terminated after the raw material completely disappeared as detected by TLC. After the reaction system was cooled to room temperature, it was transferred to a saturated sodium bicarbonate solution for neutralization, the mixture was extracted with ethyl acetate, the organic phases were combined and dried over anhydrous sodium sulfate, and the solvent was removed by concentration to obtain a crude product, which was recrystallized to obtain (3-amino-2-hydroxy-5-methylphenyl) (2-aminophenyl) ketone with a yield of 90%. 1 H NMR (400 MHz, DMSO-d6) δ 10.35(s, 1H), 7.51 (d, J = 8.0Hz, 1H), 7.08 (m, 1H), 6.94 (m, 1H), 6.85 (s, 1H), 6.82 (s, 1H) 6.65 (d, J =8.0 Hz, 1H), 6.51 (s, 2H), 5.02 (s, 2H), 2.40 (s, 3H). 13C NMR (101 MHz, DMSO-d6) δ 199.76, 149.77, 147.70, 137.12, 133.38, 131.60, 128.38, 126.00, 121.48,120.95, 119.00, 117.16, 114.98, 21.81. Theoretical elemental analysis,calculated for C 14 H 14 HRMS (ESI) calcd for C 14 H 14 N2O2 [M + H + ] 243.1134, found 243.1132.

[0133] Example 1

[0134] III-9 (54.07 g, 0.50 mol), III-2 (44.85 g, 0.20 mol), monomer II-1 (49.25 g, 0.20 mol) and monomer I-1 (24.23 g, 0.10 mol) were dissolved in 3200 ml of N-methylpyrrolidone and stirred at 10 o C. Add 4,4'-biphenyl dianhydride (294.22 g, 1.00 mol) while stirring and keep the temperature at 10 o C was polymerized for 10 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0135] The spinning slurry is spun into shape by dry-jet wet spinning technology, the spinning slurry at room temperature is accurately metered by a metering pump, extruded from a spinneret, passed through an air layer and entered into a coagulation bath of N-methylpyrrolidone and water in a volume ratio of 1:5, and then drawn, washed, and dried in a hot nitrogen channel to obtain polyamic acid fibers. The spinneret has 150 holes, a hole diameter of Φ0.12 mm, a spray-to-draw ratio of 2.5 times, a spinning speed of 60 m / min, and an air layer height of 12 mm.

[0136] The polyamic acid fiber was treated in a gradient heating imidization furnace under an argon atmosphere to obtain polyimide fiber. The thermal imidization temperature ranged from 50 to 380 o C, heating rate is 15 o C / min.

[0137] The obtained polyimide fiber was stretched 2.5 times at 470°C in a nitrogen environment to obtain a polyimide finished fiber. The fiber had a breaking strength of 2.30 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 81.3%.

[0138] Example 2

[0139] III-1 (135.16 g, 0.60 mol), monomer II-4 (75.27 g, 0.20 mol), I-5 (48.46 g, 0.20 mol) were dissolved in 2850 ml of N,N-dimethylformamide and heated at 5 o C. Add 3,4'-biphenyl dianhydride (294.22 g, 1.00 mol) while stirring, and keep the temperature at 5 o C was polymerized for 15 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0140] The spinning slurry is spun into shape by a dry-jet wet spinning process, the spinning slurry at room temperature is accurately metered by a metering pump, extruded from a spinneret, passed through an air layer and entered into a coagulation bath of ethylene glycol and water in a volume ratio of 1:4, and then drawn, washed, and dried in a hot nitrogen channel to obtain polyamic acid fibers. The spinneret has 100 holes, a hole diameter of Φ 0.15 mm, a spray-to-draw ratio of 2.5 times, a spinning speed of 70 m / min, and an air layer height of 13 mm.

[0141] The polyamic acid fiber was treated in a gradient heating imidization furnace under nitrogen environment to obtain polyimide fiber. The thermal imidization temperature ranged from 50 to 400 o C, heating rate is 10 o C / min.

[0142] The obtained polyimide fiber was heated at 480 o The finished polyimide fiber was drawn by 2.0 times C. The fiber had a breaking strength of 2.58 GPa. After ultraviolet (wavelength range 280~400nm, irradiation intensity 15W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 90.3%.

[0143] Example 3

[0144] III-11 (80.10 g, 0.40 mol), III-6 (52.27 g, 0.20 mol), II-7 (88.86 g, 0.20 mol), I-3 (33.79 g, 0.125 mol) and I-5 (30.29 g, 0.125 mol) were dissolved in 3300 ml of N,N-dimethylacetamide and heated at -10 o C. Add pyromellitic anhydride (218.12 g, 1.00 mol) while stirring, and keep the temperature at -10 o C was polymerized for 24 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0145] The spinning slurry is spun into shape by wet spinning technology, and the spinning slurry at room temperature is accurately metered by a metering pump, extruded from the spinneret hole, and directly enters into a coagulation bath of N,N-dimethylacetamide and water with a volume ratio of 1:6, and then drawn, washed, and dried in a hot nitrogen channel to obtain polyamic acid fiber. The spinneret has 300 holes, a hole diameter of φ0.14 mm, a spray-draw ratio of 3.5 times, and a spinning speed of 45 m / min.

[0146] The polyamic acid fiber was treated in a gradient heating imidization furnace under nitrogen environment to obtain polyimide fiber. The thermal imidization temperature ranged from 50 to 400 o C, the heating rate is 15℃ / min.

[0147] The obtained polyimide fiber was stretched 2.0 times at 490°C in a nitrogen environment to obtain a polyimide finished fiber. The fiber had a breaking strength of 3.05 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 92.5%.

[0148] Example 4

[0149] III-7 (102.71 g, 0.30 mol), III-9 (10.82 g, 0.10 mol), II-6 (147.75 g, 0.30 mol) and I-1 (72.69 g, 0.30 mol) were dissolved in 3200 ml of N-methylpyrrolidone and heated at 20 o C. Add 3,4'-biphenyl dianhydride (294.22 g, 1.00 mol) while stirring and keep the temperature at 20 o C was polymerized for 12 hours to obtain a viscous polyamic acid spinning solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0150] The spinning slurry is formed by dry-jet wet spinning, and the spinning slurry at room temperature is accurately measured by a metering pump, extruded from a spinneret, passed through an air layer and entered into a coagulation bath of N,N-dimethylacetamide and water in a volume ratio of 1:4, and then drawn, washed, and dried by a hot roller to obtain polyamic acid fibers. The spinneret has 500 holes, a hole diameter of φ 0.15 mm, a jet-to-pull ratio of 3.2 times, a spinning speed of 80 m / min, and an air layer height of 8 mm.

[0151] The polyamic acid fiber is treated in a gradient heating imidization furnace under a nitrogen environment to obtain polyimide fiber. The thermal imidization temperature ranges from 50 to 420 o C, heating rate is 5 o C / min.

[0152] The obtained polyimide fiber was stretched 3.0 times at 480°C in a nitrogen environment to obtain a polyimide finished fiber. The fiber had a breaking strength of 3.24 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 95.4%.

[0153] Example 5

[0154] III-12 (70.08 g, 0.35 mol), III-5 (78.70 g, 0.30 mol), II-2 (30.83 g, 0.10 mol), II-8 (34.03 g, 0.10 mol) and I-8 (42.65 g, 0.15 mol) were dissolved in 2900 ml of dimethyl sulfoxide and heated at 15 o C. Add 3,3',4,4'-benzophenone tetracarboxylic dianhydride (322.23 g, 1.00 mol) while stirring and keep the temperature at 15 o C was polymerized for 12 hours to obtain a viscous polyamic acid spinning solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0155] The spinning slurry is formed by dry-jet wet spinning, and the spinning slurry at room temperature is accurately measured by a metering pump, extruded from a spinneret, passed through an air layer and entered into a coagulation bath of dimethyl sulfoxide and water in a volume ratio of 1:5, and then drawn, washed, and dried in a hot nitrogen channel to obtain polyamic acid fibers. The spinneret has 800 holes, a hole diameter of φ 0.15 mm, a jet-to-draw ratio of 3.6 times, a spinning speed of 70 m / min, and an air layer height of 18 mm.

[0156] The polyamic acid fiber is treated in a gradient heating imidization furnace under a nitrogen environment to obtain polyimide fiber. The thermal imidization temperature ranges from 50 to 450o C, heating rate is 20 o C / min.

[0157] The obtained polyimide fiber was heated at 480 o The finished polyimide fiber was drawn 3.2 times by C. The fiber had a breaking strength of 3.15 GPa. After ultraviolet (wavelength range 280~400nm, irradiation intensity 15W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 89.5%.

[0158] Comparative Example 1 (without diamine monomer A)

[0159] III-9 (54.07 g, 0.50 mol), III-2 (44.85 g, 0.20 mol) and II-1 (49.25 g, 0.20 mol) were dissolved in 3200 ml of N-methylpyrrolidone and stirred at 10 o C. Add 4,4'-biphenyl dianhydride (264.80 g, 0.90 mol) while stirring and keep the temperature at 10 o C was polymerized for 10 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0160] The spinning slurry was spun into shape by the same spinning process as in Example 1 to obtain polyamic acid fibers, which were then treated by the same imidization process as in Example 1 to obtain polyimide fibers, and finally heat-drawn by the same process as in Example 1 to obtain polyimide finished fibers. The fiber had a breaking strength of 2.52 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 60.3%.

[0161] Comparative Example 2 (without diamine monomer B)

[0162] III-9 (54.07 g, 0.50 mol), III-2 (44.85 g, 0.20 mol) and I-1 (24.23 g, 0.10 mol) were dissolved in 3200 ml of N-methylpyrrolidone and heated at 10 o C. Add 4,4'-biphenyl dianhydride (235.38 g, 0.80 mol) while stirring and keep the temperature at 10 o C was polymerized for 10 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0163] The spinning slurry was spun into shape by the same spinning process as in Example 1 to obtain polyamic acid fibers, which were then treated by the same imidization process as in Example 1 to obtain polyimide fibers, and finally heat-drawn by the same process as in Example 1 to obtain polyimide finished fibers. The fiber had a breaking strength of 2.40 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 45.4%.

[0164] Comparative Example 3 (without diamine monomer A and diamine monomer B)

[0165] III-9 (54.07 g, 0.50 mol) and III-2 (44.85 g, 0.20 mol) were dissolved in 3200 ml of N-methylpyrrolidone and stirred at 10 o C. Add 4,4'-biphenyl dianhydride (205.95 g, 0.70 mol) while stirring and keep the temperature at 10 o C was polymerized for 10 hours to obtain a viscous polyamic acid solution, which was used as a spinning slurry after filtration and vacuum degassing.

[0166] The spinning slurry was spun into shape by the same spinning process as in Example 1 to obtain polyamic acid fibers, which were then treated by the same imidization process as in Example 1 to obtain polyimide fibers, and finally heat-drawn by the same process as in Example 1 to obtain polyimide finished fibers. The fiber had a breaking strength of 3.20 GPa and was irradiated by ultraviolet (wavelength range 280-400 nm, irradiation intensity 15 W / m 2 ) irradiated for 2000 hours, 5×10 20 atoms·cm -2 After atomic oxygen irradiation, the fiber strength retention rate is 30.9%.

[0167] Performance Testing

[0168] The imide fibers obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to UV and atomic oxygen irradiation resistance tests, and the test results are shown in Table 1 below (the fiber breaking strength test standard is GB / T 14344-2008 Chemical Fiber Filament Tensile Properties Test Method):

[0169] Table 1. Radiation resistance of polyimide fibers

[0170]

[0171] It can be seen from the data in Table 1 that the polyimide fiber prepared in the present invention has good resistance to ultraviolet radiation and atomic oxygen radiation.

[0172] In summary, the present invention copolymerizes a functional diamine monomer containing a β-hydroxyketone structure, a phosphorus-containing diamine monomer, other diamine monomers and a dianhydride monomer to obtain a spinning solution, and then adopts a dry method, a dry-spray wet method or a wet spinning process to obtain a polyamic acid fiber; and obtains a polyimide fiber through thermal imidization and thermal drawing. The fiber has excellent UV resistance and atomic oxygen resistance, and also has other excellent properties of the polyimide fiber, and can be applied to aerospace, national defense construction, weapon equipment and the like.

[0173] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A diamine monomer as shown in formula I: Formula I; in, R is selected from substituted or unsubstituted C1~C6 alkyl.

2. The diamine monomer according to formula (I) of claim 1, characterized in that: The R is selected from substituted or unsubstituted C1~C4 alkyl.

3. The diamine monomer according to formula I of claim 1 or 2, characterized in that: The diamine monomer is selected from any one of the following formulas I-1 to I-12: 。 4. The method for preparing a diamine monomer as shown in Formula I according to any one of claims 1 to 3, characterized in that: include: S1: subjecting the nitrobenzoyl compound represented by formula a to a Friedel-Crafts acylation reaction with the p-alkylanisole represented by formula b to obtain an intermediate; Formula a; Formula b; Wherein, X is selected from -OH, -Cl, -Br, -I, -OAc; R is selected from Me, Et, i Pr, t Bu; S2: Demethylating the intermediate under acidic conditions to obtain a mononitro compound, and then subjecting the mononitro compound to nitration and reduction to obtain a diamine monomer as shown in Formula I.

5. The preparation method according to claim 4, characterized in that: The molar ratio of the nitrobenzoyl compound to p-alkylanisole is (1.0-1.5):1; The temperature of the Friedel-Crafts acylation reaction is -10 to 40 o C; The temperature of the nitration reaction is -20 to 50 o C; The temperature of the reduction reaction is room temperature to 100 o C.

6. A polyimide material, characterized in that: Prepared from dianhydride monomers and diamine monomers; The diamine monomers include diamine monomer A, diamine monomer B and diamine monomer C; The diamine monomer A is a diamine monomer according to any one of claims 1 to 3 or a diamine monomer prepared by the preparation method according to claim 4 or 5; The diamine monomer B is selected from any one or more of the following formulas II-1 to II-9: ； The diamine monomer C is selected from any one or more of the following formulas III-1 to III-19: 。 7. The polyimide material according to claim 6, characterized in that: The dianhydride monomer is selected from any one or more of the following formulae: 。 8. The polyimide material according to claim 6 or 7, characterized in that: The molar ratio of the dianhydride monomer to the diamine monomer is 1:(0.9-1.5); The molar ratio of the diamine monomer A, the diamine monomer B and the diamine monomer C is: (0.05-0.5): (0.05-0.6): (0.2-1).

9. The polyimide material according to any one of claims 6 to 8, characterized in that The polyimide material includes polyimide fibers.

10. A method for preparing a polyimide material as claimed in any one of claims 4 to 9, characterized in that: include: After polymerizing the dianhydride monomer and the diamine monomer in a solvent, a polyamic acid intermediate is obtained; The polyamic acid intermediate is imidized to obtain a polyimide material.

11. The preparation method according to claim 10, characterized in that: The polyamic acid spinning solution is subjected to spinning treatment, and then to imidization and heat drawing treatment.

12. Use of the polyimide material according to any one of claims 1 to 9 or the polyimide material prepared by the preparation method according to claim 10 or 11 in the preparation of aerospace vehicles.

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