Preparation method of 4, 4 '-oxydiphthalic anhydride and application of 4, 4'-oxydiphthalic anhydride in preparation of polyimide

Abstract

The invention discloses a preparation method of 4, 4 '-diphenylmethane. The invention discloses a preparation method of 4, 4 '-oxydiphthalic anhydride and application of the 4, 4'-oxydiphthalic anhydride in preparation of polyimide, and the preparation method of the 4, 4 '-oxydiphthalic anhydride comprises the following steps: 4, 4'-oxydiphthalic anhydride and an anhydride compound are subjected to an anhydridation reaction in the presence of an organic amine catalyst and under the pressurization condition to obtain the 4, 4 '-oxydiphthalic anhydride. And 4, 4 '-oxydiphthalic anhydride is added. Compared with the prior art, the preparation method has the advantages that the organic amine catalyst and specific pressurizing conditions are utilized, the 4, 4 '-oxybisphthalimide and the anhydride compound react to obtain the 4, 4'-oxybisphthalimide, use of a large number of acid-base reagents is avoided, and the preparation method is short in synthesis process, simple in step, high in yield, high in product purity, low in metal ion content and suitable for industrial production; moreover, high-viscosity polyimide can be obtained by using the 4, 4 '-oxydiphthalic anhydride as a raw material.

Description

Technical Field

[0001] This invention belongs to the field of organic compound technology, and particularly relates to a method for preparing 4,4'-oxybisphthalic anhydride and its application in the preparation of polyimide. Background Technology

[0002] Polyimide (PI) is an organic polymer material with outstanding comprehensive properties. Polyimide resin prepared from 4,4'-oxydiphthalic anhydride (ODPA) has excellent mechanical properties, high temperature resistance, chemical corrosion resistance, low coefficient of linear expansion, and high self-orientation properties, making it widely used in aerospace, electronics, and semiconductor industries. Currently, there are two main methods for synthesizing ODPA. One method involves the self-condensation of halophthalic anhydrides under the action of an alkali metal catalyst, followed by decolorization, deionization purification, and thermal desorption to obtain the product. However, this method produces many byproducts, making purification difficult. Existing technologies disclose the self-coupling of halophthalic anhydrides under the action of ruthenium, palladium, nickel, and rhodium catalysts; however, the high cost of precious metal catalysts and the unknown yield, number of times, and effectiveness of recycling and reuse limit its application in industrial production. The other method involves the synthesis of ODPA from N-methyl-4-nitro-phthalimide through steps such as condensation, hydrolysis, acidification, decolorization purification, and dehydration to anhydride. While this method is technologically mature, the hydrolysis process requires the addition of excessive alkali, and the subsequent removal of metal ions is also quite cumbersome. In the microelectronics industry, polyimide used as a protective layer on coated devices, photoresist resin, and liquid crystal alignment film requires extremely low metal ion content (generally reaching electronic grade). Furthermore, the use of excessive sulfuric or hydrochloric acid for deacidification generates large amounts of acidic wastewater, requiring high treatment costs. Existing technologies disclose a decolorization and purification process that requires a large amount of water as a solvent, resulting in significant losses and a low overall yield, with liquid phase purity around 99.50%, limiting its application in the high-end market. On the one hand, there is an increasing demand for facilitating industrial production, optimizing lengthy process steps, and improving reaction yield and product purity; on the other hand, high-viscosity polyimide resins, due to their high strength and high-temperature stability, have wide market applications in adhesives, semiconductor packaging materials, flexible circuit boards, and high-temperature insulating materials, making a method for synthesizing high-viscosity polyimide resins urgently needed. Summary of the Invention

[0003] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a method for preparing 4,4'-oxydiphthalic anhydride (ODPA), which can obtain ODPA with high yield and low metal ion content. The preparation process does not require alkaline hydrolysis, which reduces the use of acid and base reagents and also reduces the amount of metal ions introduced.

[0004] The second objective of this invention is to provide a method for preparing polyimide (PI).

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a method for preparing 4,4'-oxobisphthalic anhydride, comprising the following steps: 4,4'-oxobisphthalimide reacts with an anhydride compound under an organic amine catalyst and pressure to undergo an anhydridation reaction, thereby obtaining the 4,4'-oxobisphthalic anhydride.

[0006] Preferably, the organic amine catalyst comprises at least one of triallylamine, triethylenediamine, N,N-diisopropylethylamine, 1,8-diazobispyrocyclo[5.4.0]undec-7-ene, or 4-dimethylaminopyridine; more preferably, the organic amine catalyst comprises at least one of triallylamine, triethylenediamine, N,N-diisopropylethylamine, or 4-dimethylaminopyridine; even more preferably, the organic amine catalyst comprises at least one of triallylamine, triethylenediamine, or N,N-diisopropylethylamine; more preferably, the organic amine catalyst is selected from triallylamine.

[0007] Preferably, the anhydride compound includes a chain anhydride compound, a cyclic anhydride compound, or a combination thereof; more preferably, the anhydride compound includes a chain anhydride compound and a cyclic anhydride compound; even more preferably, the molar ratio of the chain anhydride compound to the cyclic anhydride compound is 1:(0.3~0.7); for example, it can be any value of 1:0.3, 1:0.5, or 1:0.7, or a range between any two.

[0008] Preferably, the chain anhydride compound includes at least one of acetic anhydride, propionic anhydride, levulinic anhydride, or benzoic anhydride; more preferably, the chain anhydride compound includes acetic anhydride, benzoic anhydride, or a combination thereof; even more preferably, the chain anhydride compound is selected from acetic anhydride.

[0009] Preferably, the cyclic anhydride compound includes at least one selected from phthalic anhydride, maleic anhydride, succinic anhydride, glutaric anhydride, or itaconic anhydride; more preferably, the cyclic anhydride compound includes at least one selected from phthalic anhydride, maleic anhydride, or succinic anhydride; even more preferably, the cyclic anhydride compound is selected from phthalic anhydride.

[0010] Preferably, the molar ratio of the 4,4'-oxobisphthalimide to the anhydride compound is 1:(3~15); more preferably 1:(5~12); even more preferably 1:(7~10); for example, it can be any value of 1:7, 1:8, 1:9 or 1:10 or any range between two of them.

[0011] Preferably, the molar ratio of the 4,4'-oxobisphthalimide to the organic amine catalyst is 1:(0.05~0.5); more preferably 1:(0.1~0.4); even more preferably 1:(0.15~0.3); for example, it can be any value of 1:0.15, 1:0.2, 1:0.25 or 1:0.3 or any range between two.

[0012] Preferably, the pressurized pressure is 1~10MPa; more preferably 2~4MPa; even more preferably 2.5~3MPa; for example, it can be any value of 2.5MPa, 2.6MPa, 2.8MPa or 3MPa or any range between two of them.

[0013] Preferably, the pressurization is performed by introducing a pressurizing gas; more preferably, the pressurizing gas includes an oxidizing gas, a protective gas, or a combination thereof; in some embodiments of the present invention, the pressurizing gas includes at least one of oxygen, ozone, nitrogen dioxide, sulfur trioxide, nitrogen, argon, or helium; in some further embodiments of the present invention, the pressurizing gas is selected from oxygen.

[0014] Under pressure, the methylamino group on 4,4'-oxobisphthalimide can undergo oxygen exchange with acid anhydride compounds to generate products ODPA and amide compounds.

[0015] Preferably, the temperature of the anhydride reaction is 120~180℃; more preferably 130~170℃; even more preferably 140~160℃; for example, it can be any value of 140℃, 150℃ or 160℃ or a range between any two.

[0016] Preferably, the anhydride reaction time is 5-20 h; more preferably 8-16 h; even more preferably 10-14 h; for example, it can be any value of 10 h, 12 h or 14 h or any range between two of them.

[0017] Preferably, the 4,4'-oxobisphthalimide is prepared by a method comprising the following steps: N-methyl-4-nitrophthalimide undergoes a condensation reaction under the conditions of an alkali metal salt catalyst and a first polar solvent to obtain the 4,4'-oxobisphthalimide.

[0018] Preferably, the alkali metal salt catalyst comprises at least one of potassium acetate, sodium acetate, potassium nitrite, sodium nitrite, potassium carbonate, or sodium carbonate; more preferably, the alkali metal salt catalyst comprises potassium acetate, sodium acetate, or a combination thereof; even more preferably, the alkali metal salt catalyst is selected from potassium acetate.

[0019] Preferably, the first polar solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO); more preferably, the first polar solvent is selected from N,N-dimethylformamide (DMF).

[0020] Preferably, the molar ratio of N-methyl-4-nitrophthalimide to the alkali metal salt catalyst is 1:(0.2~1.2); more preferably 1:(0.25~1); even more preferably 1:(0.4~0.7); for example, it can be any value of 1:0.4, 1:0.5, 1:0.6 or 1:0.7 or any range between two of them.

[0021] Preferably, the mass ratio of N-methyl-4-nitrophthalimide to the first polar solvent is 1:(1~10); more preferably 1:(2~8); even more preferably 1:(3~6); for example, it can be any value of 1:3, 1:4, 1:5 or 1:6 or any range between two of them.

[0022] Preferably, the reaction temperature of the condensation reaction is 80~140℃; more preferably 90~130℃; even more preferably 100~120℃; for example, it can be any value of 100℃, 110℃ or 120℃ or a range between any two.

[0023] Preferably, the reaction time of the condensation reaction is 12 to 16 hours; for example, it can be any value of 12 hours, 14 hours, or 16 hours, or a range between any two.

[0024] Preferably, the condensation reaction is carried out in a protective gas atmosphere; more preferably, the protective gas used in the condensation reaction includes at least one of nitrogen, argon or helium; more preferably, nitrogen.

[0025] Preferably, the condensation reaction is carried out under reflux in the first polar solvent.

[0026] Preferably, the 4,4'-oxobisphthalimide is prepared by a method comprising the following specific steps: N-methyl-4-nitrophthalimide is mixed with a first polar solvent, the mixture is heated and refluxed once to separate a portion of the first polar solvent, the mixture is cooled once to add a portion of the alkali metal salt catalyst, the mixture is then heated and refluxed a second time to separate a portion of the first polar solvent, the mixture is cooled a second time to add the remaining alkali metal salt catalyst, the mixture is then heated and refluxed a third time to separate a portion of the first polar solvent, and the remaining first polar solvent is evaporated under negative pressure to obtain the 4,4'-oxobisphthalimide.

[0027] Preferably, during a single heating and reflux, the mass of the separated first polar solvent accounts for 10-20% of the total mass of the first polar solvent.

[0028] Preferably, during the first cooling, the added alkali metal salt catalyst accounts for 40-60% of the total mass of the alkali metal salt catalyst.

[0029] Preferably, during the second heating and reflux, the mass of the separated first polar solvent accounts for 8-15% of the total mass of the first polar solvent.

[0030] Preferably, during the three heating and reflux cycles, the mass of the separated first polar solvent accounts for 55-70% of the total mass of the first polar solvent.

[0031] Preferably, the reflux temperatures for the first, second, and third reflux cycles are each independently 150-160°C.

[0032] Preferably, the cooling temperatures of the primary cooling and the secondary cooling are each independently 100~120℃.

[0033] Preferably, the 4,4'-oxobisphthalimide is prepared by a method comprising the following more specific steps: N-methyl-4-nitrophthalimide is mixed with a first polar solvent, refluxed once to separate 10-30% of the first polar solvent by mass, cooled once to add 40-60% of the alkali metal salt catalyst by mass, refluxed a second time to separate 8-20% of the first polar solvent by mass, cooled a second time to add the remaining alkali metal salt catalyst, refluxed a third time for 6-10 hours to separate xx-xx% of the first polar solvent by mass, held at the temperature for 1-3 hours, and evaporated under negative pressure to obtain the 4,4'-oxobisphthalimide.

[0034] Preferably, the total metal ion content in the 4,4'-oxophthalic anhydride is ≤200 ppb; more preferably, it is 50~200 ppb; for example, it can be any value of 50 ppb, 100 ppb, 150 ppb or 200 ppb or a range between any two.

[0035] Preferably, the purity of the 4,4'-oxophthalic anhydride is ≥99%; more preferably, it is 99%~100%; for example, it can be any value or a range between 99%, 99.2%, 99.5%, 99.8% or 100%. Specifically, the purity refers to the purity measured by high performance liquid chromatography.

[0036] The preparation process of this invention does not require alkaline hydrolysis, which reduces the use of a large amount of acid and alkali reagents and also reduces the amount of metal ions introduced. The resulting 4,4'-oxophthalic anhydride has a low metal ion content and high purity.

[0037] A second aspect of the present invention provides a method for preparing a polyimide, comprising the following steps: preparing 4,4'-oxobisphthalic anhydride using the preparation method described in the first aspect of the present invention; and polymerizing the 4,4'-oxobisphthalic anhydride with a diamine in a second polar solvent to obtain the polyimide.

[0038] Preferably, the diamine comprises at least one of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-diaminodiphenylmethane (MDA), 2,2'-di(trifluoromethyl)diaminobiphenyl (TFMB), or 4,4'-diaminophenyl sulfide (TDA); more preferably, the diamine comprises at least one of 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), 2,2'-di(trifluoromethyl)diaminobiphenyl (TFMB), or 4,4'-diaminophenyl sulfide (TDA); even more preferably, the diamine comprises 2,2'-di(trifluoromethyl)diaminobiphenyl (TFMB), 4,4'-diaminophenyl sulfide (TDA), or a combination thereof.

[0039] The 4,4'-oxydiphthalic anhydride of the present invention can react with different types of diamines to obtain high-viscosity polyimides, and the raw materials are widely available.

[0040] Preferably, the second polar solvent includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), or dimethyl sulfoxide (DMSO); more preferably, the second polar solvent is selected from N,N-dimethylacetamide (DMAC).

[0041] Preferably, the water content in the second polar solvent is ≤200ppm; for example, it can be any value of 1ppm, 10ppm, 50ppm, 100ppm, 150ppm or 200ppm or a range between any two.

[0042] Preferably, the molar ratio of the 4,4'-oxophthalic anhydride to the diamine is 1:(0.5~1.5); more preferably 1:(0.8~1.2); for example, it can be any value of 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2 or any range between two.

[0043] Preferably, the mass ratio of the 4,4'-oxophthalic anhydride to the second polar solvent is 1:(5~20); more preferably 1:(8~15); for example, it can be any value of 1:8, 1:10, 1:12 or 1:15 or any range between two.

[0044] Preferably, the reaction temperature of the polymerization reaction is 10~30℃; more preferably 15~25℃; for example, it can be any value of 15℃, 20℃ or 25℃ or a range between any two.

[0045] Preferably, the reaction time of the polymerization reaction is 10 to 14 hours; for example, it can be any value of 10 hours, 12 hours, or 14 hours, or a range between any two.

[0046] Preferably, the polymerization reaction is carried out in a protective gas atmosphere; more preferably, the protective gas used in the polymerization reaction includes at least one of nitrogen, argon or helium; more preferably, nitrogen.

[0047] Preferably, the polymerization reaction is followed by a dehydration treatment; specifically, the dehydration treatment involves mixing the polymerization product formed by the polymerization reaction with toluene, heating and refluxing, and then evaporating the solvent under negative pressure to obtain polyimide.

[0048] Preferably, the polyimide has a viscosity ≥1×10⁻⁶ at 25°C. 5 cps; further preferably (1~3)×10 5 cps; for example, it could be 1×10 5 cps, 1.5×10 5 cps, 2×10 5 cps, 2.5×10 5 cps or 3×10 5 Any value in cps or a range of values ​​between any two.

[0049] The beneficial effects of this invention are as follows: This invention utilizes organic amine catalysts and specific pressurized conditions to react 4,4'-oxobisphthalimide with acid anhydride compounds to obtain 4,4'-oxobisphthalic anhydride, avoiding the use of large amounts of acid and base reagents. Furthermore, the synthesis process is short, simple, yields high, produces high-purity products with low metal ion content, and is suitable for industrial production. Additionally, using this 4,4'-oxobisphthalic anhydride as a raw material can yield high-viscosity polyimide. Attached Figure Description

[0050] Figure 1 The image shows the 1H NMR spectrum of the intermediate product 4,4'-oxobisphthalimide synthesized in Example 1.

[0051] Figure 2 The image shows the 1H NMR spectrum of the final product 4,4'-oxophthalic anhydride synthesized in Example 1.

[0052] Figure 3 This is a high-performance liquid chromatogram of the final product 4,4'-oxobisphthalic anhydride synthesized in Example 1. Detailed Implementation

[0053] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0054] Example 1 A method for preparing 4,4'-oxydiphthalic anhydride (ODPA) includes the following steps: Preparation of S1,4,4'-Oxybisphthalimide Add 360 g of N,N-dimethylformamide (DMF) to a four-necked flask equipped with a thermometer and a mechanical stirrer. After purging with nitrogen for 15 min, add 80 g of N-methyl-4-nitrophthalimide (4-NPI). Stir and heat to reflux temperature of 153 °C, separating 60 g of DMF. Cool to 100-120 °C and add 9.52 g of potassium acetate. Reheat to reflux again, separating 40 g of DMF. Cool to 100-120 °C and add another 9.52 g of potassium acetate. Continue reflux under controlled temperature control, separating 240 g of DMF after approximately 8 hours. Stop separating DMF, maintain the temperature for 2 hours, and then distill off the remaining DMF under negative pressure. Add 600 g of pure water, reflux for 60 minutes, filter while hot, dry under vacuum, and then dry in a forced-air drying oven at 80℃ for 12 hours to obtain 107.44 g of the yellowish-brown intermediate product 4,4'-oxobisphthalimide, with a yield of 82.3%. The 1H NMR spectrum of this product (…) 1 H NMR (image) Figure 1 As shown, the specific data is as follows: 1H NMR (400 MHz, CDCl3) δ 7.88 (d, J = 8.1 Hz, 2H), 7.44 (d,J = 2.1 Hz, 2H), 7.36 (dd, J = 8.1, 2.1 Hz, 2H), 3.19 (s, 6H). Preparation of S2,4,4'-O-diphthalic anhydride The intermediate obtained in step (1), 200 g of acetic anhydride, 8.77 g of triallylamine catalyst, and 148.12 g of phthalic anhydride were added to a high-pressure reactor equipped with a magnetic stir bar. Oxygen was introduced at 2.8 MPa, and the mixture was heated to 150 °C and reacted for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, depressurized, and filtered to obtain 4,4'-oxophthalic anhydride. The filter cake was washed twice with 50 g of ethyl acetate, dried under vacuum, and then placed in a vacuum oven. It was first dried at 60 °C for 12 hours, and then heated to 120 °C for 12 hours to obtain 92.33 g of the final product, 4,4'-oxophthalic anhydride, with a yield of 93.1%. The proton NMR spectrum of the final product (1H NMR spectrum) was obtained. 1 H NMR (image) Figure 2 As shown, the specific data is as follows: 1 H NMR (400 MHz, CDCl3) δ 8.11 (d, J = 9.0 Hz, 2H), 7.73 - 7.52 (m, 4H).

[0055] The high-performance liquid chromatography (HPLC) chromatogram of the final product is shown below. Figure 3 As shown in Table 1, the chromatographic peak data indicates a purity of 99.73%. The metal ion content of the final product is shown in Table 2, indicating a total metal ion content of 185 ppb.

[0056] Table 1. Chromatographic peak data of the final product 4,4'-oxophthalic anhydride from Example 1

[0057] Table 2. Metal ion content data of the final product 4,4'-oxophthalic anhydride in Example 1

[0058] Examples 2-4 A method for preparing 4,4'-oxydiphthalic anhydride (ODPA) differs from Example 1 in that the total amount of potassium acetate used in step S1 is adjusted, and the amounts used in specific steps are adjusted proportionally. The specific total amount of potassium acetate used is shown in Table 3. Other steps are the same as in Example 1. The yields under different conditions are tested and recorded in Table 3.

[0059] Table 3 Total amount of potassium acetate and corresponding yield data in Examples 1-4

[0060] As shown in Table 3, using a specific amount of potassium acetate can yield a high yield of the intermediate 4,4'-oxobisphthalimide and the final product ODPA.

[0061] Examples 5-8 A method for preparing 4,4'-oxydiphthalic anhydride (ODPA) differs from Example 1 in that the oxygen pressure in step S2 is adjusted, as shown in Table 4. All other aspects are the same as in Example 1. Yields under different conditions are tested and recorded in Table 4.

[0062] Table 4. Oxygen pressure and corresponding yield data in Examples 1, 5-8

[0063] As shown in Table 4, increasing pressure within an appropriate range can improve yield, but beyond a certain point, increasing pressure has little impact on yield. Therefore, maintaining pressure within a certain range can ensure a high yield.

[0064] Examples 9-12 A method for preparing 4,4'-oxydiphthalic anhydride (ODPA) differs from Example 1 in that the type of catalyst in step S2 is adjusted, maintaining a catalyst-to-intermediate molar ratio of 0.2:1. The specific catalyst types and their masses are shown in Table 5; otherwise, the method is the same as in Example 1. Yields under different conditions are tested and recorded in Table 5.

[0065] Table 5. Catalyst types and corresponding yield data in Examples 1, 9-12

[0066] As shown in Table 5, using a suitable catalyst can ensure a high yield of ODPA, especially the catalyst in Example 1, which achieves even better yield performance. Example 1 uses triallylamine as a highly efficient catalyst, mainly due to its unique molecular structure: three flexible allyl groups (-CH2-CH=CH2) provide abundant π electrons, which can act as multidentate coordination metal centers, stabilizing active intermediates (such as η-coefficients). 3(-allyl complex), while the lone pair electrons of the nitrogen atom assist in proton transfer or electron transport. Its moderate steric hindrance prevents catalyst deactivation without hindering substrate access to the active site, while the electron delocalization effect of the allyl group lowers the reaction energy barrier and accelerates key steps (such as oxidative addition or migration insertion). This synergistic balance of electron-steric effects makes its catalytic effect in the reaction system of this invention superior to rigid ligands (such as triphenylphosphine) or simple amine catalysts.

[0067] Example 13 A method for preparing a polyimide resin, comprising reacting ODPA prepared in Example 1 with ODA, wherein the specific steps are as follows: 72.23 g of DMAC solvent (DMAC water content less than 200 ppm) was added to a 250 mL four-necked flask equipped with a mechanical stirrer. Nitrogen gas was purged for 30 minutes while stirring. Then, 5.00 g of powdered ODA was added at 20°C. After dissolving completely, 7.75 g of ODPA was added. The mixture was stirred for 12 hours while maintaining the temperature at 20°C to obtain a colorless and transparent polyamic acid resin solution. 100 mL of toluene was added to the above solution, and the mixture was heated to 110°C and refluxed for 2 hours. After distilling off the water and all the toluene under reduced pressure, the solution was cooled to room temperature to obtain a polyimide resin with a viscosity of 154482 cps.

[0068] Examples 14-18 A method for preparing a polyimide resin differs from Example 13 in that ODA is replaced with another diamine, while maintaining a molar ratio of ODPA to diamine of 1:1. The specific types and masses of diamines are shown in Table 6, and other aspects are the same as in Example 13. The viscosity of the polyimide resin obtained under different conditions at 25°C is tested and recorded in Table 6.

[0069] Table 6. Types of diamines and viscosity data of the polyimide resins obtained in Examples 13-18

[0070] As shown in Table 6, using the ODPA prepared in the embodiments of this invention as a raw material, it can yield high-viscosity polyimide resins with different types of diamines. Among them, m-PDA is a meta-substituted diphenylamine, which may have a relatively distorted polymerization structure due to steric hindrance, resulting in a low degree of polymerization and relatively low viscosity. TFMB and TDA contain fluorine or sulfur atoms, which is beneficial for increasing the viscosity of the resin.

[0071] In summary, this invention utilizes organic amine catalysts and specific pressurized conditions to react 4,4'-oxobisphthalimide with anhydride compounds to obtain 4,4'-oxobisphthalic anhydride. This avoids the use of large amounts of acid and base reagents, and the synthesis process is short, simple, yields high, produces high-purity products with low metal ion content, making it suitable for industrial production. Furthermore, using this 4,4'-oxobisphthalic anhydride as a raw material can yield high-viscosity polyimide.

Claims

1. A process for the preparation of 4,4'-oxydiphthalic anhydride, characterized in that, The method comprises the following steps: 4,4'-oxydiphthalic anhydride is obtained by acid anhydride reaction of 4,4'-oxydiphthalimide and an acid anhydride compound under the condition of an organic amine catalyst and pressure.

2. The production method according to claim 1, characterized by, The organic amine catalyst comprises at least one of triallylamine, triethylenediamine, N,N-diisopropylethylamine, 1,8-diazobis-spiro[5.4.0]undec-7-ene or 4-dimethylaminopyridine; And / or, the acid anhydride compound comprises a chain acid anhydride compound, a cyclic acid anhydride compound or a combination thereof.

3. The preparation method according to claim 1, characterized in that, The molar ratio of the 4,4'-oxydiphthalimide to the acid anhydride compound is 1:(3-15); And / or, the molar ratio of the 4,4'-oxydiphthalimide to the organic amine catalyst is 1:(0.05-0.5).

4. The method of claim 1, wherein, The pressure of the pressure is 1-10 MPa; And / or, the temperature of the acid anhydride reaction is 120-180℃.

5. The preparation method according to claim 1, characterized in that, The 4,4'-oxydiphthalimide is prepared by a method comprising the following steps: condensation reaction of N-methyl-4-nitrophthalimide under the condition of an alkali metal salt catalyst and a first polar solvent to obtain the 4,4'-oxydiphthalimide.

6. The production method according to claim 5, wherein The alkali metal salt catalyst comprises at least one of potassium acetate, sodium acetate, potassium nitrite, sodium nitrite, potassium carbonate or sodium carbonate; And / or, the first polar solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide; And / or, the molar ratio of the N-methyl-4-nitrophthalimide to the alkali metal salt catalyst is 1:(0.2-1.2); And / or, the reaction temperature of the condensation reaction is 80-140℃.

7. The preparation method according to claim 1, characterized in that, The total metal ion content of the 4,4'-oxydiphthalic anhydride is ≤200ppb; And / or, the purity of the 4,4'-oxydiphthalic anhydride is ≥99%.

8. A method for producing a polyimide, characterized by, The method comprises the following steps: 4,4'-oxydiphthalic anhydride is prepared by the preparation method in any one of claims 1-7; polymerization reaction of the 4,4'-oxydiphthalic anhydride and a diamine in a second polar solvent to obtain the polyimide.

9. The production method according to claim 8, characterized by, The diamine comprises at least one of 4,4'-oxydianiline, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 2,2'-bis(trifluoromethyl)diaminobiphenyl or 4,4'-diaminodiphenyl sulfide; And / or, the second polar solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide; And / or, the molar ratio of the 4,4'-oxydiphthalic anhydride to the diamine is 1:(0.5-1.5); And / or, the reaction temperature of the polymerization reaction is 10-30℃.

10. The method of claim 8, wherein, The viscosity of the polyimide at 25℃ is ≥10000cps.

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