Modified polyimide resin, method of preparation and use thereof

Abstract

The application provides a modified polyimide resin, a preparation method and an application thereof. The modified polyimide resin is prepared by a method comprising the following steps: dissolving a polymethylacrylimide resin in a solvent to obtain a polymethylacrylimide resin solution; mixing the polymethylacrylimide resin solution, a monomer for synthesizing a polyimide resin and an alcohol solution containing an end-capping agent to obtain a mixture; and curing the mixture to obtain the modified polyimide resin; the monomer comprises an aromatic dianhydride and an aromatic diamine; and the mass ratio of the polymethylacrylimide resin solution, the aromatic dianhydride, the aromatic diamine and the end-capping agent is 5-20:20-40:30-55:10-40. The modified polyimide resin is modified by using a PMI resin on a PI resin, can ensure that the PMI resin is uniformly dispersed in a PI monomer system, avoids a phase separation phenomenon and lays a foundation for improving the toughness, and solves the problems of poor compatibility and easy agglomeration of a traditional toughening agent and a PI system.

Description

Technical Field

[0001] This application relates to the field of resin preparation technology, specifically to a modified polyimide resin, its preparation method, and its uses. Background Technology

[0002] Polyimide (PI) thermosetting resins possess excellent high-temperature resistance, corrosion resistance, insulation, and mechanical strength, making them widely used in aerospace, electronics, and high-end equipment industries. The PMR method is a classic approach for preparing thermosetting PI resins. It involves in-situ polymerization of monomers to form a cross-linked network structure, endowing the resin with excellent high-temperature resistance. However, PI resins prepared by the traditional PMR method suffer from high cross-linking density and rigid molecular chains, resulting in poor toughness, weak impact resistance, and a tendency to crack, thus limiting their application in scenarios requiring high toughness.

[0003] Polymethacrylimide (PMI) resin is a polymer formed by copolymerizing methacrylic acid and methacrylonitrile. It is lightweight, heat-resistant, and has a molecular chain that combines rigidity and a certain degree of flexibility. When the degree of crosslinking of PMI resin is low, its molecular chain has a high degree of freedom and contains polar groups such as carboxyl and nitrile groups, making it easily compatible with other polar polymer materials. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, this application provides a modified polyimide resin, a preparation method thereof and its uses, wherein the modified polyimide resin has excellent toughness.

[0005] The specific technical solution of this application is as follows: 1. A modified polyimide resin, prepared by a method comprising the following steps: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin; The monomer comprises an aromatic dianhydride and an aromatic diamine; The mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

[0006] 2. The modified polyimide resin according to claim 1, wherein the aromatic dianhydride is selected from one or more of the following: pyromellitic dianhydride (1,2,4,5-phenylenetetracarboxylic dianhydride), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and / or The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediphenylamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-methylenediphenylamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane; and / or The end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and / or Optionally, the solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0007] 3. The modified polyimide resin according to any one of items 1-2, wherein the mass ratio of the polymethacrylimide resin to the solvent is 10-50:100.

[0008] 4. The modified polyimide resin according to any one of items 1-3, wherein the curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, at 150-180℃ for 3-5 hours, at 220-250℃ for 4-6 hours, and at 280-320℃ for 1-3 hours to obtain the modified polyimide resin.

[0009] 5. The modified polyimide resin according to any one of claims 1-4, wherein the polymethacrylimide resin is prepared by a method comprising the steps of: (Meth)acrylic acid, (meth)acrylonitrile, initiator and foaming agent are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

[0010] 6. A method for preparing modified polyimide resin, comprising: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin; The monomer comprises an aromatic dianhydride and an aromatic diamine; The mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

[0011] 7. The method according to claim 6, wherein the aromatic dianhydride is selected from one or more of the following: 1,2,4,5-phenylenetetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and / or The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediphenylamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-methylenediphenylamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane; and / or The end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and / or The solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0012] 8. The method according to any one of items 6-7, wherein the mass ratio of the polymethacrylimide resin to the solvent is 10-50:100; Optionally, curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, 150-180℃ for 3-5 hours, 220-250℃ for 4-6 hours, and 280-320℃ for 1-2 hours to obtain modified polyimide resin.

[0013] 9. The method according to any one of items 6-8, wherein the polymethacrylimide resin is prepared by a method comprising the steps of: (Meth)acrylic acid, (meth)acrylonitrile, initiator and foaming agent are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

[0014] 10. The use of the modified polyimide resin of any one of items 1-5 or the modified polyimide resin prepared by any one of items 6-9 in the fields of aerospace, electronics and electrical engineering, CNC machine tools, high-end medical equipment or rail transportation.

[0015] Beneficial effects The modified polyimide resin described in this application uses PMI resin to modify PI resin, which can ensure that PMI resin is uniformly dispersed in the PI monomer system, avoid phase separation, lay the foundation for toughness improvement, and solve the problems of poor compatibility and easy agglomeration between traditional toughening agents and PI system.

[0016] The modified polyimide resin used is a low-crosslinking PMI resin. Due to the low degree of crosslinking of the PMI resin molecular chains, the molecular chains have high freedom and strong flexibility. After being dissolved in a solvent and added to the PI monomer, during the in-situ polymerization of PMI, the PMI molecular chains will interpenetrate in the crosslinking network of the PI resin to form a "semi-interpenetrating network structure". The dense crosslinking network of the PI resin ensures high temperature resistance, while the interpenetrating flexible PMI molecular chains can reduce the overall crosslinking density, increase the flexibility of the network, and allow the network to deform to a certain extent when subjected to force, thereby reducing stress concentration. Detailed Implementation

[0017] The present application will now be described in detail with reference to the described embodiments. Although specific embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0018] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0019] This application provides a modified polyimide resin, which is prepared by a method comprising the following steps: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin.

[0020] This application avoids phase separation by uniformly dispersing PMI resin in the monomer system of synthesized polyimide resin, which lays the foundation for improving toughness and solves the problems of poor compatibility and easy agglomeration between traditional toughening agents and polyimide resin systems.

[0021] In this application, no restrictions are placed on the alcohol in the alcohol solution containing the capping agent. It can be any alcohol commonly used in the art, such as methanol, ethanol, isopropanol, n-butanol, isobutanol, etc.

[0022] In some embodiments, the monomer comprises an aromatic dianhydride and an aromatic diamine. Optionally, the aromatic dianhydride is selected from one or more of the following: pyromellitic dianhydride (1,2,4,5-phenyltetracarboxylic dianhydride), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and / or The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-m-methylenediamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane. In some embodiments, the end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride. In some embodiments, the solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0023] In some embodiments, the mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

[0024] For example, the mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic dianhydride diamine, and capping agent can be 5:20:30:10, 5:25:30:10, 5:30:30:10, 5:35:30:10, 5:40:30:10, 5:35:35:10, 5:35:40:10, 5:35:45:10, 5: 35:50:10, 5:35:55:10, 5:35:35:15, 5:35:35:20, 5:35:35:25, 5:35:35:30, 5:35:35:35, 5:35:35:40, 10:35:35:20, 15:35:35:20, 20:35:35:20, etc., or any range thereof.

[0025] In the polymethacrylimide resin solution, the mass ratio of polymethacrylimide to solvent is 10-50:100. For example, the mass ratio of polymethacrylimide to solvent can be 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, etc., or any range between them.

[0026] In some embodiments, curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, at 150-180℃ for 3-5 hours, at 220-250℃ for 4-6 hours, and at 280-320℃ for 1-3 hours to obtain the modified polyimide resin.

[0027] For example, it can be kept at temperatures of 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, or any range thereof for 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or any range thereof; and it can be kept at temperatures of 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, or any range thereof for 3 hours, 3.5 hours, 4 hours, or any range thereof. Modified polyimide resin is obtained by holding at temperatures ranging from 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃ for 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, or any range thereof, or at temperatures ranging from 280℃, 285℃, 290℃, 300℃, 305℃, 310℃, 315℃, 320℃ for 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any range thereof, within any range of h, 4.5 hours, 5 hours, etc., or between 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃ ...

[0028] In some embodiments, the polymethacrylimide resin is prepared by a method comprising the following steps: (Meth)acrylic acid, (meth)acrylonitrile and an initiator are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

[0029] For example, polymethacrylamide resin can be obtained by polymerization at temperatures of 30℃, 35℃, 40℃, 45℃, 50℃ or any range thereof for 100h, 110h, 120h, 130h, 140h, 150h, 160h, 170h, 180h, 190h, 200h or any range thereof.

[0030] In some embodiments, the initiator is selected from one or more of tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, benzoyl peroxide lauroyl peroxide, tert-butyl peroxide, tert-butyl peroxy-2-ethylhexanoate, or bis(4-tert-butylcyclohexyl) peroxide dicarbonate.

[0031] In some embodiments, the mass ratio of (meth)acrylic acid, (meth)acrylonitrile and initiator can be 40-60:30-50:0.1-3.

[0032] For example, the mass ratio of (meth)acrylic acid, (meth)acrylonitrile, and initiator can be 40:30:0.1, 40:35:0.1, 40:40:0.1, 40:45:0.1, 40:50:0.1, 40:40:0.2, 40:40:0.2, 40:40:0.4, 40:40:0.5, 40:40:0.6, 40:40:0.7, 40:40:0.8, 40:40:0.9, 40:40:1, 40:40:1.5, 40:40:2, 40:40:2.5, 40:40:3, 45:40:0.5, 50:40:0.5, 55:40:0.5, 60:40:0.5, or any range thereof.

[0033] This application provides a method for preparing modified polyimide resin, comprising: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin.

[0034] This application disperses polymethacrylimide resin in the monomer system of synthetic polyimide resin, which can make the polymethacrylimide resin uniformly dispersed in the monomer system of synthetic polyimide resin, avoiding phase separation, laying the foundation for toughness improvement, and solving the problems of poor compatibility and easy agglomeration between traditional toughening agents and polyimide resin systems.

[0035] In this application, no restrictions are placed on the alcohol in the alcohol solution containing the capping agent. It can be any alcohol commonly used in the art, such as methanol, ethanol, isopropanol, n-butanol, isobutanol, etc.

[0036] In some embodiments, the monomer comprises an aromatic dianhydride and an aromatic diamine. Optionally, the aromatic dianhydride is selected from one or more of the following: 1,2,4,5-phenylenetetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediphenylamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-methylenediphenylamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane. In some embodiments, the end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride. In some embodiments, the solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0037] In some embodiments, the mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

[0038] For example, the mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent can be 5:20:30:10, 5:25:30:10, 5:30:30:10, 5:35:30:10, 5:40:30:10, 5:35:35:10, 5:35:40:10, 5:35:45:10, 5:35:50:10, 5:35:55:10, 5:35:35:15, 5:35:35:20, 5:35:35:25, 5:35:35:30, 5:35:35:35, 5:35:35:40, 10:35:35:20, 15:35:35:20, 20:35:35:20, etc., or any range thereof.

[0039] In the polymethacrylimide resin solution, the mass ratio of polymethacrylimide to solvent is 10-50:100. For example, the mass ratio of polymethacrylimide to solvent can be 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, etc., or any range between them.

[0040] In some embodiments, curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, at 150-180℃ for 3-5 hours, at 220-250℃ for 4-6 hours, and at 280-320℃ for 1-2 hours to obtain the modified polyimide resin.

[0041] For example, it can be kept at temperatures of 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, or any range thereof for 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or any range thereof; and it can be kept at temperatures of 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, or any range thereof for 3 hours, 3.5 hours, 4 hours, or any range thereof. Modified polyimide resin is obtained by holding at temperatures ranging from 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃ for 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, or any range thereof, or at temperatures ranging from 280℃, 285℃, 290℃, 300℃, 305℃, 310℃, 315℃, 320℃ for 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any range thereof, within any range of h, 4.5 hours, 5 hours, etc., or between 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃ ...

[0042] In some embodiments, the polymethacrylimide resin is prepared by a method comprising the following steps: (Meth)acrylic acid, (meth)acrylonitrile and an initiator are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

[0043] For example, polymethacrylamide resin can be obtained by polymerization at temperatures of 30℃, 35℃, 40℃, 45℃, 50℃ or any range thereof for 100h, 110h, 120h, 130h, 140h, 150h, 160h, 170h, 180h, 190h, 200h or any range thereof.

[0044] In some embodiments, the initiator is selected from one or more of tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, benzoyl peroxide lauroyl peroxide, tert-butyl peroxide, tert-butyl peroxy-2-ethylhexanoate, or bis(4-tert-butylcyclohexyl) peroxide dicarbonate.

[0045] In some embodiments, the mass ratio of (meth)acrylic acid, (meth)acrylonitrile and initiator can be 40-60:30-50:0.1-3.

[0046] For example, the mass ratio of (meth)acrylic acid, (meth)acrylonitrile, and initiator can be 40:30:0.1, 40:35:0.1, 40:40:0.1, 40:45:0.1, 40:50:0.1, 40:40:0.2, 40:40:0.2, 40:40:0.4, 40:40:0.5, 40:40:0.6, 40:40:0.7, 40:40:0.8, 40:40:0.9, 40:40:1, 40:40:1.5, 40:40:2, 40:40:2.5, 40:40:3, 45:40:0.5, 50:40:0.5, 55:40:0.5, 60:40:0.5, or any range thereof.

[0047] This application provides the use of the modified polyimide resin described in any one of the above claims or the modified polyimide resin prepared by the method described in any one of the above claims in the fields of aerospace, electronics and electrical engineering, CNC machine tools, high-end medical equipment or rail transportation.

[0048] Example This application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., weight percentage. Reagents or instruments used, unless otherwise specified, are all commercially available conventional reagent products.

[0049] Example 1: Preparation of Modified PI Resin Preparation of PMI resin: 50g of (meth)acrylic acid, 40g of (meth)acrylonitrile and 0.5g of azobisisobutyronitrile initiator were polymerized at a polymerization temperature of 45℃ for a polymerization time of 150h to obtain PMI resin.

[0050] Preparation of modified PI resin: 30g of PMI resin was dissolved in 100g of isopropanol polar solvent to obtain a PMI resin solution. Then, it was mixed with 277.5g of benzophenone tetracarboxylic dianhydride, 375g of diaminodiphenyl ether and 195g of 5-norbornene-2,3-dicarboxylic anhydride end-capping agent in methanol (475g) to obtain a mixed solution. The viscosity was measured using a rotational viscometer (Shanghai Changji NDJ-1) after being kept at 90℃ for 3h. The results are shown in Table 1. The modified PI resin was obtained by continuing to keep it at 170℃ for 4h, 225℃ for 5h, and 310℃ for 1.3h.

[0051] Example 2 The difference between Example 2 and Example 1 is that 10g of PMI resin was dissolved in 100g of isopropanol polar solvent to obtain a PMI resin solution, thereby preparing the modified PI resin.

[0052] Example 3 The difference between Example 3 and Example 1 is that 50g of PMI resin was dissolved in 100g of isopropanol polar solvent to obtain PMI resin solution, thereby preparing modified PI resin.

[0053] Example 4 The difference between Example 4 and Example 1 is that 5g of PMI resin was dissolved in 100g of isopropanol polar solvent to obtain a PMI resin solution, thereby preparing the modified PI resin.

[0054] Example 5 The difference between Example 5 and Example 1 is that 55g of PMI resin was dissolved in 100g of isopropanol polar solvent to obtain PMI resin solution, thereby preparing modified PI resin.

[0055] Example 6 The difference between Example 6 and Example 1 is that in the preparation of PMI resin, the polymerization temperature is 30°C to obtain PMI resin, while the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0056] Example 7 The difference between Example 7 and Example 1 is that in the preparation of PMI resin, the polymerization temperature is 50°C to obtain PMI resin, while the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0057] Example 8 The difference between Example 8 and Example 1 is that in the preparation of PMI resin, the polymerization temperature is 20°C to obtain PMI resin, while the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0058] Example 9 The difference between Example 9 and Example 1 is that in the preparation of PMI resin, the polymerization temperature is 55°C to obtain PMI resin, while the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0059] Example 10 The difference between Example 10 and Example 1 is that in the preparation of PMI resin, the polymerization time is 100h to obtain PMI resin, while the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0060] Example 11 The difference between Example 11 and Example 1 is that in the preparation of PMI resin, the polymerization time is 90h to obtain PMI resin, and the other operation methods are the same as in Example 1 to obtain modified PI resin.

[0061] Example 12 The difference between Example 12 and Example 1 is that 30g of PMI resin was dissolved in 100g of N,N-dimethylformamide polar solvent to obtain a PMI resin solution. Other operation methods were the same as in Example 1 to obtain modified PI resin.

[0062] Example 13 The difference between Example 13 and Example 1 is that 30g of PMI resin was dissolved in 100g of dimethyl sulfoxide polar solvent to obtain a PMI resin solution. Other operation methods are the same as in Example 1 to obtain modified PI resin.

[0063] Example 14 The difference between Example 14 and Example 1 is that 3g of PMI resin was dissolved in 33g of isopropanol polar solvent to obtain a PMI resin solution. Other operation methods are the same as in Example 1 to obtain modified PI resin.

[0064] Example 15 The difference between Example 15 and Example 1 is that 40g of PMI resin was dissolved in 133g of isopropanol polar solvent to obtain a PMI resin solution. Other operation methods are the same as in Example 1 to obtain modified PI resin.

[0065] Example 16 The difference between Example 16 and Example 1 is that 6g of PMI resin was dissolved in 20g of isopropanol polar solvent to obtain a PMI resin solution. Other operation methods are the same as in Example 1 to obtain modified PI resin.

[0066] Example 17 The difference between Example 17 and Example 1 is that 50g of PMI resin was dissolved in 167g of isopropanol polar solvent to obtain a PMI resin solution. Other operation methods are the same as in Example 1 to obtain modified PI resin.

[0067] Comparative Example 1 Preparation of PMI resin: The preparation was carried out according to the method described in Example 1. Preparation of the mixture: 277.5 g of benzophenone tetracarboxylic dianhydride, 375 g of diaminodiphenyl ether and 195 g of 5-norbornene-2,3-dicarboxylic anhydride end-capping agent in methanol solution (475 g) were mixed to obtain PI resin. 100 g of PI resin was mixed with PMI resin and kept at 90 °C for 3 h, at 170 °C for 4 h, at 225 °C for 5 h and at 310 °C for 1.3 h to obtain the mixture.

[0068] Experimental Example The tensile strength and elongation at break of the resins obtained in Examples 1-17 and Comparative Example 1 were determined according to ASTM D638: Standard Test Method for Tensile Properties of Plastics, and the results are shown in Table 1.

[0069] Table 1

[0070] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the protection scope of this application.

Claims

1. A modified polyimide resin, prepared by a method comprising the following steps: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin; The monomer comprises an aromatic dianhydride and an aromatic diamine; The mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

2. The modified polyimide resin according to claim 1, wherein, The aromatic dianhydride is selected from one or more of the following: pyromellitic dianhydride (1,2,4,5-phenyltetracarboxylic dianhydride), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and / or The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediphenylamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-methylenediphenylamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane; and / or The end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and / or Optionally, the solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

3. The modified polyimide resin according to any one of claims 1-2, wherein the mass ratio of the polymethacrylimide resin to the solvent is 10-50:

100.

4. The modified polyimide resin according to any one of claims 1-3, wherein the curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, at 150-180℃ for 3-5 hours, at 220-250℃ for 4-6 hours, and at 280-320℃ for 1-3 hours to obtain the modified polyimide resin.

5. The modified polyimide resin according to any one of claims 1-4, wherein the polymethacrylimide resin is prepared by a method comprising the steps described below: (Meth)acrylic acid, (meth)acrylonitrile, initiator and foaming agent are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

6. A method for preparing modified polyimide resin, comprising: Polymethacrylimide resin is dissolved in a solvent to obtain a polymethacrylimide resin solution; The polymethacrylimide resin solution, the monomers for synthesizing polyimide resin, and an alcohol solution containing a capping agent are mixed to obtain a mixture. The mixture was cured to obtain a modified polyimide resin; The monomer comprises an aromatic dianhydride and an aromatic diamine; The mass ratio of the polymethacrylimide resin solution, aromatic dianhydride, aromatic diamine, and capping agent is 5-20:20-40:30-55:10-40.

7. The method according to claim 6, wherein the aromatic dianhydride is selected from one or more of the following: 1,2,4,5-phenylenetetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA), 2,2'-dimethyl-4,4'-diaminobiphenyl, and bisphenol A type diether dianhydride; and / or The aromatic diamine is selected from one or more of 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 4,4'-methylenediphenylamine (p-MDA), 3,3-diaminobenzidine (DAB), 3,3'-methylenediphenylamine (m-MDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, and 2,2-bis(3-amino-4-hydroxyphenyl)propane; and / or The end-capping agent is selected from one or more of 4-phenylethynyl phthalic anhydride, benzoyl chloride, maleic anhydride, 4-phenylethynyl phthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and / or The solvent is a polar solvent, preferably selected from one or more of methanol, anhydrous ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

8. The method according to any one of claims 6-7, wherein the mass ratio of the polymethacrylimide resin to the solvent is 10-50:100; Optionally, curing is carried out in stages, preferably by holding at 80-100℃ for 2-4 hours, 150-180℃ for 3-5 hours, 220-250℃ for 4-6 hours, and 280-320℃ for 1-2 hours to obtain modified polyimide resin.

9. The method according to any one of claims 6-8, wherein the polymethacrylimide resin is prepared by a method comprising the steps of: (Meth)acrylic acid, (meth)acrylonitrile, initiator and foaming agent are mixed and polymerized at 30-50℃ for 100-200h to obtain polymethacrylimide resin.

10. Use of the modified polyimide resin according to any one of claims 1-5 or the modified polyimide resin prepared by the method according to any one of claims 6-9 in the fields of aerospace, electronics and electrical engineering, CNC machine tools, high-end medical equipment or rail transportation.

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