Polyetherimide and preparation method thereof

Abstract

The invention provides polyetherimide, monomers of the polyetherimide comprise bisphenol A type diether dianhydride (BPADA) and asymmetric diamine, and a keto phenyl isoindoline chain segment is introduced into the polyetherimide, so that the polyetherimide has good processability, and the heat resistance and the mechanical property are improved. The preparation method is simple and easy to control, polyetherimide can be obtained with high yield, and the preparation method is easy to popularize and apply in large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of polyetherimide, and particularly relates to a polyetherimide containing an asymmetric diamine structural unit and a preparation method thereof. Background Art

[0002] Polyetherimide is a thermoplastic polyimide. Thermoplastic polyimide is developed on the basis of traditional thermosetting polyimide (PI) and is named TPI. It refers to a class of heterocyclic polymers containing imide groups in the main chain of the macromolecule. It not only retains the high strength, high temperature resistance, chemical corrosion resistance, good dielectric properties, and radiation resistance of traditional thermosetting polyimide, but also improves the processability of thermoplastic polyimide. Thermoplastic polyimide can be widely used in aerospace, automobile, electronic appliances, precision machinery and other fields due to its excellent comprehensive properties. It can be made into plates, rods or tubes, films and structural composite precision parts, such as gears, bearings, connectors, etc. In certain occasions, it is an ideal material to replace metals, ceramics, low-temperature or difficult-to-process thermosetting resins.

[0003] At present, the most successfully modified TPI development and application is polyetherimide (Ultem) produced by GE in the United States in the 1950s and 1960s, which has good solubility and processability, excellent dielectric properties, and a tensile strength of up to 50Mpa, so this type of material has been widely used. However, its heat resistance is insufficient and its glass transition temperature is low, which limits its application in fields with higher requirements for heat resistance. In addition, the two-step method of polyetherimide in the existing invention requires ring opening at room temperature and ring closure at elevated temperature, which is complicated and cannot ensure that PAA polyamic acid (PAA) is completely ring-closed.

[0004] Therefore, it is necessary to further develop polyetherimide to obtain better heat resistance and toughness on the basis of good processability, simplify the process, reduce three wastes, reduce costs, and improve product yield. Summary of the invention

[0005] To solve the above problems, the present invention provides a thermoplastic polyetherimide, which is synthesized by designing an asymmetric diamine as one of the monomers, and is prepared by polycondensation with bisphenol A diether dianhydride (BPADA) and aromatic diamine, and has good mechanical properties, heat resistance and processability. The preparation method uses a diamine small molecule monomer to prepare the polyetherimide in one step, and the degree of polymerization is controlled. The preparation method is simple, easy to operate and control, and reduces costs. The solvent is non-toxic and recyclable, which is conducive to scale expansion and promotion in actual production.

[0006] The object of the present invention is to provide a polyetherimide comprising the following structural units:

[0007]

[0008] Optionally, the polyetherimide further comprises the following structural units:

[0009]

[0010] Wherein, R is one of the arylene groups.

[0011] The present invention also aims to provide a polyetherimide, which is obtained by polymerization reaction of asymmetric diamine and bisphenol A diether dianhydride as monomers, and optionally, the monomers participating in the reaction also include aromatic diamine.

[0012] Another object of the present invention is to provide a method for preparing polyetherimide, characterized in that the method uses asymmetric diamine and bisphenol A diether dianhydride (BPADA) as monomers to obtain polyetherimide through polymerization reaction, and optionally, the monomers participating in the reaction also include aromatic diamine.

[0013] The polyetherimide provided by the present invention has the following beneficial effects:

[0014] (1) The regular structure of the current polyimide will form an intermolecular charge transfer (CT) effect, forming a CT complex between polymer chains, which makes the polyimide have good heat resistance and poor processability. Good heat resistance and good processability are often not achieved at the same time. The present invention is based on bisphenol A diether dianhydride, and introduces a novel asymmetric diamine into the polymerization system to prepare a series of polyetherimides with novel structures containing different proportions of asymmetric diamines, which have both high heat resistance and good processability and have good application prospects.

[0015] (2) The polyetherimide provided by the present invention is prepared by one-step polymerization, the process is simple, easy to control, no special equipment is required, the solvent is recyclable, the cost is low, and the obtained polyimide has a high degree of polymerization and high yield, which can be extended to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The p-APAPA, m-APAPA and o-APAPA of the present invention are shown. 1 H NMR spectra;

[0017] Figure 2 FTIR graphs of p-APAPA, m-APAPA, and o-APAPA of the present invention are shown;

[0018] Figure 3 The polyetherimide I (PEI-pm-cresol) prepared in Example 4 of the present invention is shown. 1 H NMR spectrum;

[0019] Figure 4 FTIR spectra of polyetherimide I PEI-pm-cresol, polyetherimide II PEI-mm-cresol, polyetherimide IV PEI-p-SA and polyetherimide V PEI-m-SA of the present invention are shown;

[0020] Figure 5 The polyetherimide VII-4 (PEI-up 41 -m-cresol) 1 H NMR spectrum;

[0021] Figure 6 The polyetherimide VIII-1 (PEI-um 14 -m-cresol) 1 H NMR spectrum. DETAILED DESCRIPTION

[0022] The present invention is described in detail below through specific implementation modes, and the characteristics and advantages of the present invention will become clearer and more specific with these descriptions.

[0023] The present invention provides a polyetherimide comprising the following structural units:

[0024]

[0025] Optionally, the polyetherimide further comprises the following structural units:

[0026]

[0027] Wherein, R is one of the arylene groups, preferably an arylene group containing one or two benzene rings, more preferably Right now

[0028] The glass transition temperature of the polyetherimide is higher than 215° C., and may be higher than 220° C., and may even be higher than 230° C. The elongation at break of the polyetherimide is higher than 3.0%, and may even be higher than 3.5%.

[0029] The monomers for preparing the polyetherimide of the present invention include bisphenol A diether dianhydride (BPADA) and asymmetric diamine. A ketophenyl isoindoline chain segment is introduced into the polyetherimide, so that the polyetherimide has good processability, and the heat resistance and mechanical properties are improved.

[0030] The invention provides a polyetherimide, which is obtained by polymerization reaction of asymmetric diamine and bisphenol A diether dianhydride (BPADA) as monomers. Optionally, the reaction monomers also include aromatic diamine.

[0031] The present invention also provides a method for preparing polyetherimide, wherein the method uses asymmetric diamine and bisphenol A diether dianhydride (BPADA) as monomers to obtain polyetherimide through polymerization. Optionally, the reaction monomers also include aromatic diamine.

[0032] The asymmetric diamine is One or more of One of the for or

[0033] The asymmetric diamine is obtained by using 4-nitrophthalic anhydride and nitroaniline as raw materials to react to obtain an imide intermediate product, which is then reduced by nitro group.

[0034] The nitroaniline is one or more of o-nitroaniline, p-nitroaniline and m-nitroaniline, preferably o-nitroaniline, p-nitroaniline or m-nitroaniline.

[0035] The imide intermediate is

[0036] First, 4-nitrophthalic anhydride and nitroaniline are added to solvent A, and heated to react under a protective atmosphere. After the reaction is completed, post-treatment is performed to obtain an imide intermediate product.

[0037] The molar ratio of the 4-nitrophthalic anhydride to the nitroaniline is 1:(0.7-1.5), preferably 1:(0.8-1.3), and more preferably 1:(0.9-1.1).

[0038] The solvent A is selected from one or more of amide solvents and aromatic hydrocarbon solvents, preferably one or more of N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), toluene and xylene, more preferably a mixed solvent of DMAC and toluene.

[0039] The molar volume ratio of the 4-nitrophthalic anhydride to the solvent A is 0.1 mol:(160-280) mL, preferably 0.1 mol:(180-260) mL, and more preferably 0.1 mol:(200-240) mL.

[0040] In the reaction for preparing the imide intermediate product, the reaction temperature is 130-220° C., preferably 140-200° C., more preferably 150-180° C., and the reaction time is 6-14 h, preferably 7-12 h, more preferably 8-10 h.

[0041] The post-treatment includes cooling, product precipitation, washing and drying to obtain an imide intermediate product.

[0042] The imide intermediate product is then added to solvent B, a catalyst is added, and the mixture is heated to react under the action of hydrogen to reduce the nitro group and obtain the asymmetric diamine.

[0043] The solvent B is selected from one or more of alcohol solvents, ether solvents and ester solvents, preferably one or more of alkanol solvents, more preferably one or more of methanol, propanol, isopropanol and butanol.

[0044] The mass volume ratio of the imide intermediate product to the solvent B is 5 g:(160-360) mL, preferably 5 g:(200-320) mL, and more preferably 5 g:(240-280) mL.

[0045] The catalyst is selected from one or more palladium catalysts, preferably one or more supported palladium catalysts, and more preferably palladium on carbon (Pd / C).

[0046] The mass ratio of the imide intermediate product to the catalyst is 5:(0.1-0.9), preferably 5:(0.2-0.7), and more preferably 5:(0.3-0.5).

[0047] The hydrogen pressure is 1.5-5 MPa, preferably 2-4.5 MPa, more preferably 2.5-4 MPa. The reaction temperature is 45-75° C., preferably 50-70° C., more preferably 55-65° C. The reaction time is 3-11 h, preferably 4-9 h, more preferably 5-7 h.

[0048] After the reduction reaction is completed, the catalyst is filtered out while hot, and part of the solvent B is evaporated off until crystals are observed to precipitate. The mixture is slowly crystallized at -10 to -2°C, and the crystals are washed to obtain an asymmetric diamine.

[0049] The bisphenol A type diether dianhydride is:

[0050]

[0051] The aromatic diamine is preferably selected from one or more of phenylenediamine and 4,4'-diaminodiphenyl sulfone (DDS), and more preferably metaphenylenediamine (MPDA) and / or DDS.

[0052] The ratio of the total molar amount of the asymmetric diamine and aromatic diamine monomers to the molar amount of bisphenol A diether dianhydride (BPADA) is 1:(0.5-1.5), preferably 1:(0.7-1.3), and more preferably 1:(0.9-1.1).

[0053] When the aromatic diamine is added, the molar ratio of the asymmetric diamine to the aromatic diamine is 1:(0.1-5.2), preferably 1:(0.15-4.7), and more preferably 1:(0.2-4.2).

[0054] In the preparation method of the polyetherimide, a monomer is added into a reaction solvent, a catalyst is optionally added, heating is performed, polymerization reaction is carried out, and post-treatment is performed to obtain the polyetherimide.

[0055] The reaction solvent is selected from one or more acidic organic solvents, preferably one or more phenolic and carboxylic acid solvents, more preferably one or more of m-cresol, salicylic acid, benzoic acid and 5-chlorosalicylic acid.

[0056] The molar volume ratio of the total molar amount of the monomers to the reaction solvent is 10 mmol:(6-35) mL, preferably 10 mmol:(8-30) mL, and more preferably 10 mmol:(10-25) mL.

[0057] Optionally, a water-carrying agent is added, selected from one or more halogenated hydrocarbon solvents, preferably one or more halogenated aromatic hydrocarbons, more preferably one or more halogenated benzenes, such as chlorobenzene. The water-carrying agent can bring the water produced in the reaction back to the reaction system, and the water returns the acidic reaction solvent to the system to ensure the stability of the reaction. The volume ratio of the water-carrying agent to the reaction solvent is 2: (4-18), preferably 2: (6-16), and more preferably 2: (8-14).

[0058] The catalyst is selected from one or more of quinoline compounds, organic amines, alkali metal salt compounds of alcohols and alkyl lithiums, preferably one or more of quinolines and organic amines, more preferably isoquinoline and / or triethylamine.

[0059] The total molar ratio of the catalyst to the monomer is (1-6):10, preferably (1.5-5):10, and more preferably (2-4):10.

[0060] The polymerization reaction is carried out under a protective atmosphere, such as nitrogen and / or argon, with stirring.

[0061] The polymerization reaction temperature is 120-210° C., preferably 140-200° C., more preferably 160-190° C., and the polymerization reaction time is 3-32 h, preferably 4-28 h, more preferably 5-24 h.

[0062] The post-treatment includes cooling, product precipitation, washing and drying.

[0063] After the polymerization reaction is completed, the reaction solution is cooled naturally to room temperature, and a precipitation solvent is added to precipitate the product.

[0064] The precipitation solvent is one or more alcohol solvents, preferably one or more of methanol, propanol, isopropanol and butanol, such as methanol.

[0065] The washing is carried out at 70-90° C., preferably with a precipitation solvent to fully wash the product precipitate. After drying, polyetherimide is obtained.

[0066] The polymerization reaction of the present invention adopts one-step polymerization of each monomer to obtain polyetherimide, the method is simple, no complicated equipment is required, the process conditions are mild, easy to control, the solvent can be recycled, the yield is high, and it is easy to promote and apply in industry.

[0067] Example

[0068] Example 1

[0069] At room temperature, add 4-nitroaniline (about 0.1 mol, 13.8 g) and 4-nitrophthalic anhydride (about 0.1 mol, 19.3 g), 100 ml of DMAC and 120 ml of toluene into a three-necked flask. Keep the reaction system under N2 atmosphere and use a Dean-Sreak trap to separate water. Heat from room temperature to 165°C under stirring for 9 hours, then stop heating, keep stirring and let it cool to room temperature by itself; then keep stirring and slowly add 250 ml of distilled water to obtain a light yellow precipitate, wash the light yellow precipitate with distilled water for 3 times, and then dry it in a vacuum oven (60°C / 12h) to obtain p-NPNPA with a mass yield of 99.4%. At room temperature, 5 g of p-NPNPA, 0.375 g of Pd / C catalyst and 250 ml of methanol were added to a high-pressure reactor, and the air was replaced by H2 for 3 times. The pressure was maintained at 3 MPa by passing H2, and the reaction was carried out at 60°C for 6 h. After the reaction was completed, the catalyst was filtered out while hot, and part of the methanol was evaporated (crystals were observed to precipitate in the rotary evaporator), and the mixture was placed in a -4°C refrigerator overnight for slow crystallization. The crystals were washed with ice methanol for 3 times to obtain bright yellow crystals to obtain p-APAPA with a mass yield of 75%. Its hydrogen nuclear magnetic resonance spectrum 1 H NMR Figure 1 As shown, the Fourier infrared spectrum FTIR is as follows Figure 2 shown.

[0070] p-APAPA:

[0071] Example 2

[0072] m-APAPA was prepared according to the method in Example 1. The only difference was that 3-nitroaniline was used instead of 4-nitroaniline. The mass yield was 75%. 1 H NMR spectrum Figure 1 As shown, the FTIR spectrum is Figure 2 shown.

[0073] m-APAPA:

[0074] Example 3

[0075] o-APAPA was prepared according to the method in Example 1. The only difference was that 2-nitroaniline was used instead of 4-nitroaniline. The mass yield was 75%. 1 H NMR spectrum Figure 1 As shown, the FTIR spectrum is Figure 2 shown.

[0076] o-APAPA:

[0077] Example 4

[0078] Weigh 1.2654 g of p-APAPA and 2.6006 g of BPADA into a dry Schlenk reaction tube, then add 20 ml of m-cresol and 0.2 mL of isoquinoline. Seal the reaction tube and maintain a N2 atmosphere. Heat the temperature from room temperature to 180°C with stirring for 24 hours and then stop heating.

[0079] The mixture was stirred and allowed to cool naturally to room temperature. The obtained polymer solution was then slowly poured into 250 ml of vigorously stirred methanol for precipitation to obtain light yellow spherical polymer precipitates. The product was washed 3 times (1.5 h-2 h / time) with 250 ml of methanol at 80 ° C. The product was dried under vacuum (60 ° C / 12 h, 70 ° C / 1 h, 80 ° C / 1 h, 90 ° C / 1 h, 100 ° C / 6 h) to obtain a fibrous product polyetherimide I (PEI-pm-cresol) with a mass yield of 92%. 1 H NMR spectrum Figure 3 As shown, the FTIR spectrum is Figure 4 As shown. It is speculated that polyetherimide I includes the following repeating units:

[0080]

[0081] Example 5

[0082] Polyetherimide II (PEI-mm-cresol) was prepared according to the method in Example 4. The only difference was that an equal amount of m-APAPA was weighed instead of p-APAPA. The mass yield of polyetherimide II was 92%. 1 H NMR spectrum Figure 3 As shown, the FTIR spectrum is Figure 4 shown.

[0083] It is speculated that polyetherimide II includes the following repeating units:

[0084]

[0085] Example 6

[0086] Polyetherimide III (PEI-om-cresol) was prepared according to the method in Example 4, except that an equal amount of o-APAPA was weighed to replace p-APAPA. The mass yield was 91%.

[0087] It is speculated that polyetherimide III includes the following repeating units:

[0088]

[0089] Example 7

[0090] At room temperature, 1.2654 g of p-APAPA and 2.6006 g of BPADA were weighed and added to a dry Schlenk reaction tube, and salicylic acid (16 g) and chlorobenzene (2 ml) were added in sequence. The reaction tube was sealed and maintained in a N2 atmosphere, ensuring that the reaction mixture was completely immersed in an oil bath at 170°C, and maintained at 170°C for 10-15 min to allow the salicylic acid solid to completely melt, stirred for 5 hours, cooled to below 100°C, poured onto a flat aluminum foil and cooled to room temperature, ground and poured into hot methanol for washing 3 times, filtered and dried to obtain an amber product polyetherimide IV (PEI-p-SA), with a mass yield of 90%, and its FTIR spectrum is as follows: Figure 4 As shown. 1 The peak position of H NMR spectrum is similar to that of polyetherimide I (PEI-pm-cresol).

[0091] Example 8

[0092] Polyetherimide V (PEI-m-SA) was prepared according to the method in Example 7. The only difference was that an equal amount of m-APAPA was weighed instead of p-APAPA, and the mass yield was 92%. The FTIR spectrum of polyetherimide V is shown in Figure 4 As shown. 1 The peak position of HNMR spectrum is similar to that of polyetherimide II (PEI-mm-cresol).

[0093] Example 9

[0094] Polyetherimide VI (PEI-o-SA) was prepared according to the method in Example 7. The only difference was that an equal amount of o-APAPA was weighed to replace p-APAPA, and the mass yield was 89%. 1 The peak position of H NMR spectrum is similar to that of polyetherimide III (PEI-om-cresol).

[0095] Example 10

[0096] Weigh MPDA (meta-phenylenediamine), p-APAPA and 2.6006 g BPADA and add them into a dry Schlenk reaction tube, then add 20 mL of meta-cresol and 0.2 mL of catalyst isoquinoline, seal the reaction tube and maintain a N2 atmosphere, heat the temperature from room temperature to 180°C with stirring for 24 hours, then stop heating, keep stirring and allow it to cool naturally to room temperature; then slowly pour the obtained polymer solution into 250 ml of vigorously stirred methanol for precipitation to obtain a light yellow fibrous polymer precipitate, wash the product with 250 ml of methanol at 80°C for 3 times (1.5h-2h / time), and dry under vacuum (60°C / 12h, 70°C / 1h, 80°C / 1h, 90°C / 1h, 100°C / 6h). Weigh the masses of four groups of p-APAP and MPDA: 0.2531 g and 0.4323 g, 0.5062 g and 0.3242 g, 0.7593 g and 0.2161 g, 1.0123 g and 0.1081 g, respectively, to obtain the fibrous product polyetherimide VII-1 (PEI-up 14 -m-cresol), polyetherimide VII-2 (PEI-up 23 -m-cresol), polyetherimide VII-3 (PEI-up 32 -m-cresol), polyetherimide VII-4 (PEI-up 41 -m-cresol), with mass yields of 89%, 92%, 94% and 91%, respectively.

[0097] Polyetherimide VII-4 1 H NMR spectrum Figure 5 .

[0098] It is speculated that polyetherimide VII-1, polyetherimide VII-2, polyetherimide VII-3, and polyetherimide VII-4 include the following repeating units:

[0099]

[0100] Embodiment 11

[0101] According to the method in Example 10, polyetherimide VIII-1 (PEI-um 14 -m-cresol), polyetherimide VIII-2 (PEI-um 23 -m-cresol), polyetherimide VIII-3 (PEI-um 32 -m-cresol), polyetherimide VII-4 (PEI-um 41 -m-cresol), the only difference being that an equal amount of m-APAPA was used instead of p-APAPA, with mass yields of 90%, 92%, 93% and 91%, respectively.

[0102] Polyetherimide VIII-1 1 H NMR spectrum Figure 6 .

[0103] It is speculated that polyetherimide VIII-1, polyetherimide VIII-2, polyetherimide VIII-3, and polyetherimide VIII-4 include the following repeating units:

[0104]

[0105] Example 12

[0106] 2.6006g BPADA was added to a dry Schlenk reaction tube, followed by salicylic acid (16g), MPDA and p-APAPA, and chlorobenzene (2ml), and the reaction tube was sealed and maintained under N2 atmosphere. Ensure that the reaction mixture is completely immersed in an oil bath at 170°C, and maintain at 170°C for 10-15min to allow the salicylic acid solid to completely melt. Stir the reaction for 5h, cool to below 100°C, pour onto a flat aluminum foil and cool to room temperature, grind into granules, pour into hot methanol and wash 3 times, filter and dry to obtain an amber product. Weigh the masses of four groups of p-APAP and MPDA: 0.2531g and 0.4323g, 0.5062g and 0.3242g, 0.7593g and 0.2161g, 1.0123g and 0.1081g, respectively, to obtain the fibrous product polyetherimide Ⅸ-1 (PEI-up 14 -SA), polyetherimide Ⅸ-2 (PEI-up 23 -SA), polyetherimide Ⅸ-3 (PEI-up 32 -SA), polyetherimide Ⅸ-4 (PEI-up 41 -SA), with mass yields of 90%, 92%, 89% and 90%, respectively.

[0107] Polyetherimide IX-1 (PEI-up 14 -SA), polyetherimide Ⅸ-2 (PEI-up 23 -SA), polyetherimide Ⅸ-3 (PEI-up 32 -SA), polyetherimide Ⅸ-4 (PEI-up 41 -SA) 1 The peak positions of the H NMR spectrum were respectively similar to those of the polyetherimide VII-1 (PEI-up 14 -m-cresol), polyetherimide VII-2 (PEI-up 23 -m-cresol), polyetherimide VII-3 (PEI-up 32 -m-cresol), polyetherimide VII-4 (PEI-up41 -m-cresol).

[0108] Example 13

[0109] Polyetherimide X-1 (PEI-um 14 -SA), polyetherimide Ⅹ-2 (PEI-um 23 -SA), polyetherimide Ⅹ-3 (PEI-um 32 -SA), polyetherimide Ⅹ-4 (PEI-um 41 -SA), the only difference being that an equal amount of m-APAP was added instead of p-APAP, and the mass yields were 90%, 93%, 89% and 90%, respectively.

[0110] Polyetherimide Ⅹ-1(PEI-um 14 -SA), polyetherimide Ⅹ-2 (PEI-um 23 -SA), polyetherimide Ⅹ-3 (PEI-um 32 -SA), polyetherimide Ⅹ-4 (PEI-um 41 -SA) 1 The peak positions of the H NMR spectrum were respectively similar to those of the polyetherimide VIII-1 (PEI-um 14 -m-cresol), polyetherimide VIII-2 (PEI-um 23 -m-cresol), polyetherimide VIII-3 (PEI-um 32 -m-cresol), polyetherimide VII-4 (PEI-um 41 -m-cresol).

[0111] Embodiment 14

[0112] Polyetherimide XI-1 (PEI-ep 14 -SA), polyetherimide Ⅺ-2 (PEI-ep 23 -SA), polyetherimide Ⅺ-3 (PEI-ep 32 -SA), polyetherimide Ⅺ-4 (PEI-ep 41 -SA). The only difference is that an equal molar amount of 4,4'-diaminodiphenyl sulfone (DDS) is used instead of MPDA. The masses of p-APAP and DDS are: 0.2531g and 0.9932g, 0.5062g and 0.7449g, 0.7593g and 0.4966g, 1.0123g and 0.2483g. The mass yields are 94%, 92%, 89% and 90%, respectively.

[0113] It is speculated that polyetherimide XI-1, polyetherimide XI-2, polyetherimide XI-3, and polyetherimide XI-4 include the following repeating units:

[0114]

[0115] Embodiment 15

[0116] Polyetherimide XII-1 (PEI-em 14 -SA), polyetherimide Ⅻ-2 (PEI-em 23 -SA), polyetherimide Ⅻ-3 (PEI-em 32 -SA), polyetherimide Ⅻ-4 (PEI-em 41 -SA), the only difference being that an equal amount of m-APAP was added instead of p-APAP. The mass yields were 94%, 92%, 89% and 91% respectively.

[0117] It is speculated that polyetherimide XII-1, polyetherimide XII-2, polyetherimide XII-3 and polyetherimide XII-4 include the following repeating units:

[0118]

[0119]

[0120] Example 16

[0121] DDS, p-APAPA and 2.6006 g BPADA were added to a dry Schlenk reaction tube, and then 20 ml of m-cresol and 0.2 ml of catalyst isoquinoline were added. The reaction tube was sealed and maintained in a N2 atmosphere. The temperature was raised from room temperature to 180°C with stirring for 24 hours, and then heating was stopped. The stirring was maintained and the mixture was allowed to cool naturally to room temperature. The obtained polymer solution was then slowly poured into 250 ml of vigorously stirred methanol for precipitation to obtain a light yellow fibrous polymer precipitate. The product was washed 3 times (1.5 h-2 h / time) at 80°C with 250 ml of methanol, and the product was dried under vacuum (60°C / 12 h, 70°C / 1 h, 80°C / 1 h, 90°C / 1 h, 100°C / 6 h). The masses of the four groups of p-APAP and DDS were: 0.2531 g and 0.9932 g, 0.5062 g and 0.7449 g, 0.7593 g and 0.4966 g, 1.0123 g and 0.2483 g, and the fibrous product polyetherimide XⅢ-1 (PEI-ep 14 -m-cresol), polyetherimide XⅢ-2 (PEI-ep 23 -m-cresol), polyetherimide XⅢ-3 (PEI-ep 32-m-cresol), polyetherimide XⅢ-4 (PEI-ep 41 -m-cresol), with mass yields of 93%, 92%, 90% and 90%, respectively.

[0122] Polyetherimide XⅢ-1(PEI-ep 14 -m-cresol), polyetherimide XⅢ-2 (PEI-ep 23 -m-cresol), polyetherimide XⅢ-3 (PEI-ep 32 -m-cresol), polyetherimide XⅢ-4 (PEI-ep 41 -m-cresol) 1 The peak positions of the H NMR spectrum were respectively similar to those of the polyetherimide XI-1 (PEI-ep 14 -SA), polyetherimide Ⅺ-2 (PEI-ep 23 -SA), polyetherimide Ⅺ-3 (PEI-ep 32 -SA), polyetherimide Ⅺ-4 (PEI-ep 41 -SA) is similar.

[0123] Embodiment 17

[0124] Polyetherimide XIV-1 (PEI-em 14 -m-cresol), polyetherimide XⅣ-2 (PEI-em 23 -m-cresol), polyetherimide XⅣ-3 (PEI-em 32 -m-cresol), polyetherimide XⅣ-4 (PEI-em 41 -m-cresol), the only difference being that an equal amount of m-APAP was added instead of p-APAP. The mass yields were 92%, 92%, 90% and 90% respectively.

[0125] Polyetherimide Ⅺ-1 (PEI-ep 14 -SA), polyetherimide Ⅺ-2 (PEI-ep 23 -SA), polyetherimide Ⅺ-3 (PEI-ep 32 -SA), polyetherimide Ⅺ-4 (PEI-ep 41 -SA) 1 The peak positions of the H NMR spectrum were respectively similar to those of the polyetherimide XII-1 (PEI-em 14 -SA), polyetherimide Ⅻ-2 (PEI-em 23 -SA), polyetherimide Ⅻ-3 (PEI-em32 -SA), polyetherimide Ⅻ-4 (PEI-em 41 -SA) is similar.

[0126] Comparative Example

[0127] At room temperature, weigh 0.5403g of MPDA and 2.6006g of BPADA and add them to a dry Schlenk reaction tube, then add salicylic acid (16g) and chlorobenzene (2ml) in sequence. Seal the reaction tube and maintain N2 atmosphere, ensure that the reaction mixture is completely immersed in an oil bath at 170°C, maintain at 170°C for 10-15min to completely melt the salicylic acid solid, stir the reaction for 5h, cool to below 100°C, pour onto a flat aluminum foil and cool to room temperature, grind and pour into hot methanol to wash 3 times, filter and dry to obtain a light yellow product Ultem, with a mass yield of 92%.

[0128] Experimental example

[0129] The polyetherimide IX-1 (PEI-up 14 -SA), polyetherimide Ⅸ-2 (PEI-up 23 -SA), polyetherimide Ⅸ-3 (PEI-up 32 -SA), polyetherimide Ⅸ-4 (PEI-up 41 The glass transition temperature Tg and elongation at break of the Ultem prepared in the above examples are shown in the following table.

[0130] Table 1

[0131]

[0132] From the data in Table 1, it can be seen that the elongation at break and Tg of polyetherimide IX-1 to polyetherimide IX-4 prepared in the present invention are significantly improved compared with Ultem, which indicates that they have good processability, toughness and other mechanical properties and heat resistance.

[0133] The present invention is described in detail above in conjunction with specific embodiments and / or exemplary examples and drawings, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A polyetherimide comprising the following structural units: Optionally, the polyetherimide further comprises the following structural units: in, R is one of arylene groups.

2. The polyetherimide according to claim 1, characterized in that R is an arylene group containing one or two benzene rings, preferably 3. A polyetherimide, characterized in that The invention uses asymmetric diamine and bisphenol A type diether dianhydride as monomers and is obtained through polymerization reaction. Optionally, the monomers participating in the reaction also include aromatic diamine.

4. A method for preparing polyetherimide, characterized in that: The method uses asymmetric diamine and bisphenol A diether dianhydride (BPADA) as monomers to obtain polyetherimide through polymerization reaction. Optionally, the monomers participating in the reaction also include aromatic diamine.

5. The method according to claim 4, characterized in that The asymmetric diamine is One or more of the following; The aromatic diamine is selected from one or more of phenylenediamine and 4,4'-diaminodiphenyl sulfone, preferably m-phenylenediamine and / or 4,4'-diaminodiphenyl sulfone.

6. The method according to claim 4, characterized in that The ratio of the total molar amount of the asymmetric diamine and aromatic diamine monomers to the molar amount of bisphenol A diether dianhydride is 1:(0.5-1.5), preferably 1:(0.7-1.3), more preferably 1:(0.9-1.1), When the aromatic diamine is added, the molar ratio of the asymmetric diamine to the aromatic diamine is 1:(0.1-5.2), preferably 1:(0.15-4.7), and more preferably 1:(0.2-4.2).

7. The method according to claim 4, characterized in that The reaction solvent is selected from one or more acidic organic solvents, preferably one or more phenolic and carboxylic acid solvents, more preferably one or more of m-cresol, salicylic acid, benzoic acid and 5-chlorosalicylic acid. The molar volume ratio of the total molar amount of the monomers to the reaction solvent is 10 mmol:(6-35) mL, preferably 10 mmol:(8-30) mL, and more preferably 10 mmol:(10-25) mL.

8. The method according to claim 4, characterized in that Optionally, a water-carrying agent is added, which is selected from one or more halogenated hydrocarbon solvents, preferably one or more halogenated aromatic hydrocarbons, and more preferably one or more halogenated benzenes.

9. The method according to claim 4, characterized in that The catalyst is selected from one or more of quinoline compounds, organic amines, alkali metal salt compounds of alcohols and alkyl lithiums, preferably one or more of quinoline compounds and organic amines, more preferably isoquinoline and / or triethylamine.

10. The method according to claim 4, characterized in that The polymerization reaction temperature is 120-210° C., preferably 140-200° C., more preferably 160-190° C., and the polymerization reaction time is 3-32 h, preferably 4-28 h, more preferably 5-24 h.

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