A reactive polyimide resin, a preparation method and application thereof

Abstract

This invention belongs to the field of low-dielectric materials technology, and provides a reactive polyimide resin, its preparation method, and its applications. This reactive polyimide resin is constructed by polycondensation and imidization of an indene-containing diamine with different dianhydrides to form a polyimide backbone containing indene structural units. Then, maleic anhydride is used to end-cap the molecular chain, introducing maleic end groups. This reactive polyimide resin can maintain a low dielectric constant and low dielectric loss, while its molecular structure design allows for targeted control of thermal properties, dimensional stability, dielectric retention after moisture absorption, and processing adaptability. This meets the comprehensive performance requirements of the resin system for various applications such as prepregs, circuit boards, multilayer films, semiconductor sealing materials, and semiconductor devices.

Description

Technical Field

[0001] This invention belongs to the field of low dielectric materials technology, specifically relating to a reactive polyimide resin, its preparation method, and its application. Background Technology

[0002] In recent years, fields such as high-frequency and high-speed copper-clad laminates, encapsulants, prepregs, multilayer films, and semiconductor packaging have placed higher comprehensive requirements on resin systems. Related materials not only need to possess high glass transition temperatures (Tg), excellent thermal stability, and dimensional stability, but also need to maintain low dielectric constants (Dk) and dielectric losses (Df) at the target frequency band, and have suitable solubility, viscosity stability, impregnation properties, and lamination processing windows during manufacturing. Especially in high-frequency and high-speed electronic materials, the dielectric properties, thermomechanical properties, and dielectric retention after moisture absorption of the resin system directly affect signal transmission quality and long-term device reliability.

[0003] Maleimide resins have long been an important system among electronic-grade thermosetting resins due to their high heat resistance and good electrical properties. Traditional bismaleimide (BMI) resins typically achieve high heat resistance by increasing the crosslinking density, but in practical applications, these systems often suffer from problems such as brittle cured products, insufficient crack resistance, narrow processing windows, and high melting points, easy crystallization, and insufficient solubility of some monomers.

[0004] To improve traditional BMI systems, maleimide solutions incorporating indane frameworks or multiple indane structural units have emerged in recent years. Represented by Chinese patent CN113727970A published by DIC, "Maleimide, Curable Resin Composition and Cured Product," the core of this approach is to provide a maleimide compound with an indane framework. The relevant claims set the average number of repeating units n in the indane framework portion to 0.95-10.0, and this type of indane-containing maleimide improves heat resistance, solubility, and dielectric properties. Subsequent composition patents, such as CN113748149A "Cureable Resin Composition", further combine this type of maleimide (A) with an indane skeleton and a polyphenylene ether compound (B) with reactive double bonds, and cover the average number of repeating units n of this type of maleimide to 0.5-20 in the claims; another example, CN113728019B "Cureable Resin Composition", discloses a system that combines this type of maleimide (A) with an indane skeleton, an amine compound (B), and an epoxy resin (C).

[0005] The above disclosures all indicate that the core technology of the DIC route mainly lies in using maleimide containing an indimium skeleton as the main functional resin, and then achieving a balance between heat resistance, dielectric properties and a certain degree of flexibility by selecting co-reactive components or adjusting the number of indimium repeating units n.

[0006] However, as can be seen from the publicly available technical solutions, the performance regulation of this type of technical route is still mainly based on the bulk structure of indene-containing maleimide and the variation of its degree of polymerization n. In other words, the main regulation methods are, on the one hand, adjusting the repetition degree of the multi-indene units, and on the other hand, balancing dielectric properties, heat resistance, and flexibility by introducing external co-reacting components such as polyphenylene ether and amine / epoxy. In other words, the main chain backbone of this type of solution is essentially still an "indene-containing maleimide oligomer structure." From a materials design perspective, this presents an objective limitation: when existing solutions aim to further reduce the dielectric constant or dielectric loss, it often requires reducing the system polarity, increasing the free volume, or introducing more compliant structural units. However, such adjustments may adversely affect thermal stability, dimensional stability, or high-temperature modulus. Conversely, when the system aims to further improve heat resistance and dimensional stability, the increased rigidity of chain segments and the hardening of the crosslinking network can easily affect dielectric properties, processing window, or the toughness of the cured product.

[0007] Therefore, in this type of route centered on "indene-containing maleimide bulk + co-reactive components", performance regulation is more about making trade-offs and balancing between low dielectric and thermal / dimensional stability, while the degree of freedom of regulation is mainly concentrated on the polymerization degree n of the multi-indene unit and the configuration of the added reactive components. Summary of the Invention

[0008] To address the aforementioned shortcomings in the prior art, this invention provides a reactive polyimide (PI) resin, its preparation method, and its applications. This reactive polyimide resin, by introducing different dianhydride PI backbones, establishes a more effective structural control pathway compared to simply adjusting indene-containing repeating units. This enables the resin to achieve a better overall balance between low dielectric strength, low loss, dielectric retention after moisture absorption, and thermal performance, thereby meeting the comprehensive performance requirements of the resin system for different application scenarios such as prepregs, circuit boards, multilayer films, semiconductor sealing materials, and semiconductor devices.

[0009] To achieve the above objectives, the solution adopted by the present invention is as follows: A reactive polyimide resin having the structure of formula A: Formula A In this context, R independently represents an alkyl group having 1-5 carbon atoms, a represents the number of R, a=1-4, and R can be located at any substituted position within the same benzene ring; n = 1 - 50, m = 1 - 30; The number average molecular weight (Mn) of inverse polyimide resin is 1000-20000; The molecular weight distribution (Mw / Mn) of reactive polyimide resins ranges from 1.2 to 6.0. Ar is a tetravalent residue formed after removing two anhydride rings from a dianhydride monomer; Ar is selected from organic tetravalent groups with 6-40 carbon atoms.

[0010] Furthermore, in a preferred embodiment of the present invention, the structure of formula A is as follows: Formula A In this context, each R independently represents an alkyl group having 1 to 5 carbon atoms.

[0011] Furthermore, in a preferred embodiment of the present invention, Ar is selected from at least one of monocyclic aromatic groups, fused-ring aromatic groups, cyclic aromatic groups, aromatic groups containing bridging bonds, alicyclic groups, polycyclic groups containing imide ring structures, and heterocyclic groups containing heteroatoms.

[0012] Furthermore, in a preferred embodiment of the present invention, the bridging bond is selected from at least one of -O-, -CO-, -S-, -SO2-, -C(CH3)2-, and -C(CF3)2-.

[0013] Further, in a preferred embodiment of the present invention, Ar is selected from at least one of the aromatic groups in pyromellitic dianhydride, the aromatic groups in biphenyl dianhydride, the aromatic groups in benzophenone dianhydride, the aromatic groups in diphenyl ether dianhydride, and the aromatic groups in 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

[0014] A method for preparing the above-mentioned reactive polyimide resin includes: polycondensing dianhydride with an indane-containing diamine to form polyamic acid; imidizing the polyamic acid to form a polyimide prepolymer; and then end-capping it with maleic anhydride to obtain the final product.

[0015] Furthermore, in a preferred embodiment of the present invention, the dianhydride is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, benzophenone dianhydride, diphenyl ether dianhydride, and fluorinated dianhydride.

[0016] Furthermore, in a preferred embodiment of the present invention, the indane-containing diamine is selected from at least one of monomeric indane-containing diamines, oligomeric indane-containing diamines, and polymeric indane-containing diamines.

[0017] Further, in a preferred embodiment of the present invention, the method includes: (1) dissolving an indene-containing diamine in a solvent, controlling the temperature at 0-40°C; after stirring and dissolving under nitrogen protection, adding dianhydride, reacting at 20-40°C for 2-4 hours to obtain a polyamic acid solution with a solid content of 10-40%; the equivalence ratio of dianhydride to indene-containing diamine based on functional group equivalence is 0.01-1.00:1.00; (2) subjecting the polyamic acid solution to thermal imidization and / or chemical imidization to obtain a polyamic acid prepolymer; (3) cooling the reaction system to 25-50°C, adding maleic anhydride, the equivalence ratio of maleic anhydride to reactive amine groups at the molecular end groups of the reactive polyimide resin being 1.00-1.20:1, reacting for 2 hours, adding a catalyst, then heating to 120°C for dehydration and ring-closure reaction for 4 hours, followed by post-treatment to obtain the reactive polyimide resin.

[0018] Furthermore, in a preferred embodiment of the present invention, in step (1), the ratio of the amount of indane-containing diamine to the solvent is 1:2.8-3.5.

[0019] Furthermore, in a preferred embodiment of the present invention, in step (3), the catalyst is selected from at least one of inorganic salts, organic acids, solid acids or ion exchange resins.

[0020] Furthermore, in a preferred embodiment of the present invention, in step (3), the ratio of the indane-containing diamine to the catalyst is 1:0.08-0.1.

[0021] Furthermore, in a preferred embodiment of the present invention, in step (3), the post-processing includes: water washing and / or neutralization, desolventization, and filtration.

[0022] Further, in a preferred embodiment of the present invention, in step (2), thermal imidization includes: heating the polyamic acid solution to 150-160°C and reacting for 2 hours to carry out the imidization reaction, and then heating it to 210-220°C and reacting for 3 hours to obtain the polyamic acid prepolymer.

[0023] The use of the above-mentioned reactive polyimide resin in the preparation of curable resin compositions.

[0024] Furthermore, in a preferred embodiment of the present invention, the curable resin composition is a resin varnish with a solid content of 30-70%.

[0025] The use of the above-mentioned curable resin composition in the preparation of cured products, prepregs, laminated films and semiconductor sealing materials.

[0026] An application of the above-mentioned prepreg in the fabrication of circuit boards.

[0027] Application of the above-mentioned semiconductor sealing material in the fabrication of semiconductor devices.

[0028] The beneficial effects of the reactive polyimide resin, its preparation method, and its application provided by this invention are as follows: (1) The reactive polyimide resin provided by the present invention establishes a new performance regulation dimension through structural reconstruction at the main chain level, resulting in a reactive polyimide resin with a novel chemical structure. (2) The reactive polyimide resin provided by the present invention is constructed by polycondensation and imidization of indene-containing diamine with different dianhydrides to form a polyimide main chain containing indene structural units, and then by using maleic anhydride to end-cap the molecular chain to introduce maleic structural end groups. Through this design, this application establishes a triple synergistic regulatory system encompassing the polymerization degree of the indene structural unit, the structural characteristics of the dianhydride, and the polymerization degree of the polyimide backbone. This regulatory system enables the resin to leverage the heat resistance, dimensional stability, and thermomechanical framework provided by the polyimide backbone, while simultaneously utilizing the curable reactivity and coupling ability with thermosetting networks provided by the maleic end groups. This establishes a more effective structural regulation path compared to simply adjusting the indene-containing repeating units, allowing the resin to achieve a better overall balance between low dielectric strength, low loss, dielectric retention after moisture absorption, and thermal properties. This resin holds promise for achieving a better overall balance between maintaining low dielectric properties and improving thermal / dimensional stability in high-frequency, high-speed electronic materials. (3) The reactive polyimide resin provided by the present invention, based on the above-mentioned structural regulation, provides better processing adjustment space and application adaptation basis for subsequent varnish preparation, impregnation, lamination and electronic material application; (4) The preparation method of the reactive polyimide resin provided by the present invention controls the metering of raw materials, main chain construction, introduction of end groups and key process parameters, providing a process basis for the stable preparation, quality monitoring and subsequent application of the resin system, so that the material can maintain good structural consistency and performance repeatability under scale-up production conditions. Attached Figure Description

[0029] Figure 1 This is the GPC diagram of indanediamine provided in Experimental Example 1 of the present invention; Figure 2 This is the FTIR spectrum of indanediamine provided in Experimental Example 1 of the present invention; Figure 3 This is the GPC diagram of the product provided in Experimental Example 1 of the present invention; Figure 4 This is the FTIR spectrum of the product provided in Experimental Example 1 of the present invention; Figure 5 This is the GPC diagram of indanediamine provided in Experimental Example 2 of the present invention; Figure 6This is the FTIR spectrum of indanediamine provided in Experimental Example 2 of the present invention; Figure 7 This is the GPC diagram of the product provided in Experimental Example 2 of the present invention; Figure 8 This is the FTIR spectrum of the product provided in Experimental Example 2 of the present invention; Figure 9 This is the GPC diagram of the product provided in Experimental Example 3 of the present invention; Figure 10 This is the FTIR spectrum of the product provided in Experimental Example 3 of the present invention; Figure 11 This is a GPC diagram of the product provided in Comparative Example 1 of the present invention; Figure 12 This is the FTIR spectrum of the product provided in Comparative Example 1 of the present invention; Figure 13 This is the GPC diagram of the product provided in Comparative Example 2 of the present invention; Figure 14 This is the FTIR image of the product provided in Comparative Example 2 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0031] The GPC chromatogram mentioned above refers to a gel permeation chromatogram; the DSC chromatogram refers to a differential scanning calorimetry chromatogram; and the FTIR chromatogram refers to an infrared spectrum.

[0032] The following is a detailed description of a reactive polyimide resin, its preparation method, and its application provided by embodiments of the present invention.

[0033] This invention provides a reactive polyimide resin having the structure of formula A: Formula A In this context, R independently represents an alkyl group having 1-5 carbon atoms, a represents the number of R, a=1-4, and R can be located at any substituted position within the same benzene ring; n = 1 - 50, m = 1 - 30; The number average molecular weight (Mn) of inverse polyimide resin is 1000-20000; The molecular weight distribution (Mw / Mn) of reactive polyimide resins ranges from 1.2 to 6.0. Ar is a tetravalent residue formed after removing two anhydride rings from a dianhydride monomer; Ar is selected from organic tetravalent groups with 6-40 carbon atoms.

[0034] Furthermore, as a preferred embodiment, the structure of formula A is as follows: In this context, each R independently represents an alkyl group having 1 to 5 carbon atoms.

[0035] Wherein, Ar is selected from at least one of monocyclic aromatic groups, fused-ring aromatic groups, bicyclic aromatic groups, aromatic groups containing bridged bonds, alicyclic groups, polycyclic groups containing imide ring structures, and heterocyclic groups containing heteroatoms. The bridged bond is selected from at least one of -O-, -CO-, -S-, -SO2-, -C(CH3)2-, and -C(CF3)2-.

[0036] More preferably, Ar is selected from at least one of the aromatic groups in pyromellitic dianhydride, biphenyl dianhydride, benzophenone dianhydride, diphenyl ether dianhydride, and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

[0037] This invention also provides a method for preparing the above-mentioned reactive polyimide resin, comprising: polycondensing dianhydride with an indane-containing diamine to form polyamic acid; imidizing the amic acid to form a polyimide prepolymer, and then end-capping it with maleic anhydride to obtain the final product.

[0038] The dianhydride is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, benzophenone dianhydride, diphenyl ether dianhydride, and fluorinated dianhydride; the indane-containing diamine is selected from at least one of monomeric indane-containing diamine, oligomeric indane-containing diamine, and polymeric indane-containing diamine.

[0039] The equivalence ratio of maleic anhydride to reactive amine groups at the molecular end groups of reactive polyimide resin is 1.00-1.20.

[0040] The specific preparation process includes: (1) Dissolve the indane-containing diamine in a solvent at a ratio of 1:2.8-3.5, and control the temperature at 0-40℃; after stirring and dissolving under nitrogen protection, add dianhydride and react at 20-40℃ for 2-4 hours to obtain a polyamic acid solution with a solid content of 10-40%; the equivalent ratio of dianhydride to indane-containing diamine based on functional group equivalent is 0.1-1:1.00; (2) The polyamic acid solution is subjected to thermal imidization and / or chemical imidization to obtain a polyamic acid prepolymer; The reaction routes for steps (1) and (2) are as follows:

[0041] The thermal imidization process includes: heating the polyamic acid solution to 150-160℃ for 2 hours to carry out the imidization reaction, and then heating it to 210-220℃ for 3 hours to obtain the polyamic acid prepolymer. (3) Cool the reaction system to 25-50℃, add maleic anhydride, the equivalent ratio of maleic anhydride to reactive amino groups of the molecular end group of reactive polyimide resin is 1.00-1.20:1, react for 2 h, add catalyst, then heat to 120℃ for dehydration and ring closure reaction for 4 h, and then perform post-treatment to obtain reactive polyimide resin; The reaction route for step (3) is as follows:

[0042] The catalyst is selected from at least one of inorganic salts, organic acids, solid acids, or ion exchange resins; in this application, p-toluenesulfonic acid-hydrate / p-toluenesulfonic acid is preferred; the ratio of indane-containing diamine to catalyst is 1:0.08-0.1. Post-treatment includes: water washing and / or neutralization, solvent removal under reduced pressure, and filtration.

[0043] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0044] Example 1 This embodiment provides a method for preparing reactive polyimide resin: The indane-containing diamine was prepared according to method CN113727970A, and the equivalent of the indane-containing diamine amino group was 667 g / eq. The GPC chromatogram of the indane-containing diamine is shown in [reference needed]. Figure 1 As shown, the FTIR spectrum of the diamine containing the indene-manifold structure is shown in [reference needed]. Figure 2 As shown; In a reactor equipped with a thermometer, condenser, stirrer, and nitrogen inlet, 100 parts of indanediamine (1 equivalent based on amino groups) and 300 parts of NMP solvent were added. After dissolving under nitrogen protection by stirring, pyromellitic dianhydride (PMDA) was added at an amino equivalent of 0.5. The mixture was reacted at 20°C for 4 hours to obtain a polyamic acid solution. Then, the temperature was raised to 150°C and reacted for 2 hours to carry out an imidization reaction. The temperature was then raised to 220°C and reacted for 3 hours, while NMP was removed to obtain a polyimide prepolymer solution. The reaction system was then cooled to 50°C, and 300 parts of toluene were added to dissolve the compound. Maleic anhydride was then added at an end-group equivalent of 1.1 equivalents for a 2-hour end-group capping reaction. Subsequently, 10 parts of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for a dehydration and ring-closing reaction for 4 hours, resulting in the formation of a maleimide structure at the end groups. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product, the structure of which is shown in Formula A1. Formula A1.

[0045] The product's number-average molecular weight, as determined by GPC, is approximately 7000. The GPC and infrared spectroscopy results are shown below. Figure 3 and Figure 4 .

[0046] Example 2 This embodiment provides a method for preparing reactive polyimide resin: The indane-containing diamine was prepared according to method CN113727970A, and the equivalent of the indane-containing diamine amino group was 459 g / eq. The GPC chromatogram of the indane-containing diamine is shown in [reference needed]. Figure 5 As shown, the FTIR spectrum of the diamine containing the indene-manifold structure is shown in [reference needed]. Figure 6 As shown; In a reactor equipped with a thermometer, condenser, stirrer, and nitrogen inlet, 100 parts of indanediamine (1 equivalent based on amino equivalent) and 280 parts of DMAC solvent were added. After dissolving under nitrogen protection, biphenyl dianhydride (BPDA) was added at an amino equivalent to anhydride equivalent ratio of 1.00:0.4. The reaction was carried out at 20°C for 4 hours to form a polyamic acid solution. Then, the temperature was raised to 160°C for an imidization reaction for 2 hours, and then raised to 220°C for 3 hours, while DMAC was removed to obtain a polyimide prepolymer. The reaction system was cooled to 50°C, and 300 parts of toluene were added to dissolve the product. Maleic anhydride was then added at an end-group equivalent of 1.1 equivalents to perform a 2-hour end-group capping reaction. Subsequently, 8 parts of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for a dehydration and ring-closure reaction for 4 hours to form a maleimide structure at the end group. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product, the structure of which is shown in Formula A2. Formula A2.

[0047] The GPC and infrared test results are shown below. Figure 7 and Figure 8 .

[0048] Example 3 This embodiment provides a method for preparing a reactive polyimide resin: wherein the indane-containing diamine is prepared using the method described in Example 2; In a reactor equipped with a thermometer, condenser, stirrer, and nitrogen inlet, 100 parts of indanediamine (1 equivalent based on amino equivalent) and 350 parts of NMP solvent were added. After dissolving under nitrogen protection, benzophenone tetracarboxylic dianhydride (BTDA) was added at an amino equivalent to anhydride equivalent ratio of 1.00:0.4. The reaction was carried out at 20°C for 4 hours to form a polyamic acid solution. Subsequently, 10 parts of hydrated p-toluenesulfonic acid were added and the temperature was raised to 120°C for imidization to form a polyimide prepolymer. The reaction system was cooled to 25°C, and 300 parts of toluene were added to dissolve the mixture. Maleic anhydride was then used for end-group capping reaction at 1.1 equivalents for 2 hours. Subsequently, 18 parts of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for dehydration and ring-closure reaction for 4 hours to form a maleimide structure at the end group. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product. The structure of the product is shown in Formula A3. Formula A3.

[0049] The GPC and infrared test results are shown below. Figure 9 and Figure 10 .

[0050] Example 4 This embodiment provides a method for preparing a reactive polyimide resin: wherein the indane-containing diamine is prepared using the method described in Example 2; In a reactor equipped with a thermometer, condenser, stirrer, and nitrogen inlet, 100 parts of indanediamine (1 equivalent based on amino group equivalent) and 320 parts of NMP solvent were added. After dissolving under nitrogen protection by stirring, diphenyl ether tetracarboxylic dianhydride (ODPA) was added at a rate of 0.4 equivalents of anhydride. The reaction was carried out at 25°C for 3 hours to obtain a polyamic acid solution. Subsequently, the temperature was raised to 150°C and reacted for 2 hours to carry out an imidization reaction, and then the temperature was raised to 210°C and reacted for 3 hours, while NMP was removed to obtain a polyimide prepolymer. The reaction system was cooled to 50°C, and 300 parts of toluene were added to dissolve the product. Maleic anhydride was then added at an end-group equivalent of 1.1 equivalents for a 2-hour end-group capping reaction. Subsequently, 10 parts of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for a dehydration and ring-closure reaction for 4 hours to form a maleimide structure at the end group. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product, the structure of which is shown in Formula A4. Formula A4.

[0051] Example 5 This embodiment provides a method for preparing a reactive polyimide resin: wherein the indane-containing diamine is prepared using the method described in Example 2; In a reactor equipped with a thermometer, condenser, stirrer, and nitrogen inlet, 100 parts of indanediamine (1 equivalent based on amino groups) and 330 parts of NMP solvent were added. After dissolving under nitrogen protection, 4,4'-(hexafluoroisopropylidene) phthalic anhydride (6FDA) was added at an anhydride equivalent of 0.4. The mixture was reacted at 20°C for 3 hours to obtain a polyamic acid solution. Subsequently, the temperature was raised to 150°C and reacted for 2 hours to carry out an imidization reaction, followed by a further increase to 220°C and reaction for 3 hours, while simultaneously removing NMP to obtain a polyimide prepolymer. The reaction system was cooled to 50°C, and 300 parts of toluene were added to dissolve the product. Maleic anhydride was then added at an end-group equivalent of 1.1 equivalents for a 2-hour end-group capping reaction. Subsequently, 10 parts of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for a dehydration and ring-closure reaction for 4 hours to form a maleimide structure at the end group. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product, the structure of which is shown in Formula A5. Formula A5.

[0052] Comparative Example 1 This comparative example provides a method for preparing a polyimide resin: wherein the indane-containing diamine is prepared using the method described in Example 2; In a reaction vessel equipped with a thermometer, condenser, water separator, and stirrer, 100 parts of polyindane-structured diamine, 400 parts of toluene, and 100 parts of DMF were added and dissolved completely under stirring. Maleic anhydride was added to the reaction system at 20°C at an amino equivalent to maleic anhydride equivalent ratio of 1:2.1. After the addition was completed, the reaction was continued at room temperature for 2 hours to generate a maleamic acid intermediate. Subsequently, 10 parts of p-toluenesulfonic acid-hydrate were added to the reaction system as a catalyst, and the temperature was raised to 130℃ for dehydration and ring-closure reaction for 8 hours. The water generated in the reaction was continuously removed by a water separator. After the reaction was completed, the system was cooled to room temperature, and the solvent was removed under reduced pressure to obtain the product. The structure of the product is shown in Formula A6. Formula A6.

[0053] The GPC and infrared test results are shown below. Figure 11 and Figure 12 .

[0054] Comparative Example 2 This comparative example provides a method for preparing a polyimide resin: wherein the indane-containing diamine is prepared using the method described in Example 1; In a reaction vessel equipped with a thermometer, condenser, water separator, and stirrer, 100 parts of polyindane-structured diamine, 300 parts of toluene, and 100 parts of DMF were added and dissolved under stirring. Maleic anhydride was added to the reaction system at 20°C at a ratio of amino equivalent to maleic anhydride equivalent of 1:2.2. After the addition was completed, the reaction was continued at room temperature for 2 hours to generate a maleamic acid intermediate. Subsequently, 10 parts of p-toluenesulfonic acid-hydrate were added to the reaction system as a catalyst, and the temperature was raised to 130℃ to carry out a dehydration and ring-closure reaction. Water was continuously removed by azeotropic means to close the maleamic acid ring and form a maleimide structure. The reaction continued until the molecular weight of the system increased. After the reaction was completed, the solvent was removed under reduced pressure to obtain the product. The structure of the product is shown in Formula A7. Formula A7.

[0055] The GPC and infrared test results are shown below. Figure 13 and Figure 14 .

[0056] Experimental Example 1 The resins prepared in Examples 1-5 and Comparative Examples 1-2 were dried at 80-100℃ under vacuum for 4 hours. A suitable amount of resin was then placed in a mold and cured by hot pressing. The curing procedure was as follows: 180℃ / 1h, 200℃ / 1h, 220℃ / 1h, 280℃ / 1h. The samples were then cooled to room temperature in the oven to obtain pure resin cured sheets with a thickness of 0.5-1.0 mm for performance testing. The test results are shown in Table 1. The test items included dielectric properties, DMA, and CTE. Dielectric testing: Dielectric performance testing can refer to the method in IPC-TM-650 2.5.5.15 for testing the relative permittivity and loss tangent of printed circuit board substrate using a split-pillar dielectric resonator. This method is applicable to the testing of Dk and Df in the range of 1 GHz to 20 GHz. Moisture absorption treatment can be performed according to the method in IPC-TM-650 2.6.2.1. In this application, the dielectric performance is tested after 1 h of moisture absorption to compare the changing trend of dielectric parameters of each sample under short-term moisture absorption conditions. DMA (Dynamic Mechanical Analysis) Test: The glass transition temperature of the cured resin is tested using a dynamic thermomechanical analyzer (DMA). The cured sheet is cut into test strips of specified size, and the test is conducted under nitrogen or air atmosphere at a fixed heating rate. The storage modulus, loss modulus, and tanδ are recorded as curves of temperature change, and the temperature corresponding to the peak value of tanδ is taken as DMA Tg. CTE (Coefficient of Thermal Expansion) Test: The linear coefficient of thermal expansion (CTE) of the cured resin is tested using a thermomechanical analyzer (TMA). The cured sheet is cut into samples of specified dimensions, and the test is conducted under a set load and heating rate. The sample size changes with temperature, and the linear coefficient of thermal expansion is calculated within a specified temperature range. The test results are shown in Table 1: Table 1

[0057] As shown in Table 1, Comparative Examples 1 and 2 are bismaleimide systems containing indene without the introduction of the PI backbone. Their performance is mainly controlled by adjusting the number of repeating units or the degree of prepolymerization. The results show that while Comparative Example 2 reduces Df compared to Comparative Example 1, DMA and Tg also decrease simultaneously, indicating that there is still a balance between low loss and heat resistance when relying solely on repeating units.

[0058] Examples 1-5 respectively introduced dianhydrides such as PMDA, BPDA, BTDA, ODPA, and 6FDA into a diamine containing an indene structure to construct a polyimide backbone, and further capped it with maleic anhydride to form a reactive polyimide resin. Compared with the comparative examples, the dry dielectric constant (Df) of Examples 1-5 was 0.00082-0.00239, and the Df after 1 hour of moisture absorption was 0.00148-0.00290, both significantly lower than 0.00452 of Comparative Example 1 after moisture absorption and 0.00358 of Comparative Example 2 after moisture absorption. This indicates that introducing dianhydrides into the polyimide backbone can effectively reduce dielectric loss and improve dielectric stability under moisture absorption conditions. By introducing different dianhydride structures, the properties of the resulting reactive polyimide resins were significantly regulated.

[0059] In summary, the results above indicate that by introducing different dianhydrides into the indene-containing diamine system to construct the PI backbone, this application can establish a more effective structural control pathway than simply adjusting the indene-containing repeating units. This allows the resin to achieve a better overall balance between low dielectric strength, low loss, dielectric retention after moisture absorption, and thermal properties. Furthermore, different dianhydride PI backbones can be targeted to meet different application requirements.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reactive polyimide resin, characterized in that: The reactive polyimide resin has the structure of formula A: Formula A In this context, R independently represents an alkyl group having 1-5 carbon atoms, a represents the number of R, a=1-4, and R is located at any substituted position within the same benzene ring; n = 1 - 50, m = 1 - 30; The number-average molecular weight Mn of the reactive polyimide resin is 1000-20000; The molecular weight distribution (Mw / Mn) of the reactive polyimide resin is 1.2-6.0; Ar is selected from at least one of the aromatic groups in pyromellitic dianhydride, biphenyl dianhydride, benzophenone dianhydride, diphenyl ether dianhydride, and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

2. The reactive polyimide resin according to claim 1, characterized in that: The structure of formula A is as follows: Formula A In this context, each R independently represents an alkyl group having 1 to 5 carbon atoms.

3. A method for preparing a reactive polyimide resin as described in any one of claims 1-2, characterized in that: include: Polyamic acid is formed by polycondensation of dianhydride and diamine containing indane structure; the polyamic acid is then imidized to form a polyimide prepolymer, which is then end-capped with maleic anhydride to obtain the final product.

4. The method for preparing the reactive polyimide resin according to claim 3, characterized in that: The dianhydride is selected from at least one of pyromellitic dianhydride, biphenyl dianhydride, benzophenone dianhydride, diphenyl ether dianhydride, and fluorinated dianhydride.

5. The method for preparing the reactive polyimide resin according to claim 3, characterized in that: The indane-containing diamine is selected from at least one of monomeric indane-containing diamines, oligomeric indane-containing diamines, and polymeric indane-containing diamines.

6. The method for preparing the reactive polyimide resin according to claim 3, characterized in that: include: (1) Dissolve the indane-containing diamine in a solvent and control the temperature at 0-40℃; After being dissolved by stirring under nitrogen protection, the dianhydride is added, and the mixture is reacted at 20-40°C for 2-4 hours to obtain a polyamic acid solution with a solid content of 10-40%; the equivalent ratio of the dianhydride to the indene-containing diamine is 0.01-1.00:1.00 based on the functional group equivalent. (2) The polyamic acid solution is subjected to thermal imidization and / or chemical imidization to obtain the polyimide prepolymer; (3) Cool the reaction system to 25-50℃, add the maleic anhydride, the equivalent ratio of the maleic anhydride to the reactive amino group of the molecular end group of the reactive polyimide resin is 1.00-1.20:1, react for 2 h, add the catalyst and then heat to 120℃ for dehydration and ring closure reaction for 4 h, and then perform post-treatment to obtain the reactive polyimide resin.

7. The method for preparing the reactive polyimide resin according to claim 6, characterized in that: In step (1), the ratio of the indane-containing diamine to the solvent is 1:2.8-3.

5.

8. The method for preparing the reactive polyimide resin according to claim 6, characterized in that: In step (3), the catalyst is selected from at least one of inorganic salts, organic acids, solid acids or ion exchange resins.

9. The method for preparing reactive polyimide resin according to claim 8, characterized in that: In step (3), the ratio of the indane-containing diamine to the catalyst is 1:0.08-0.

1.

10. The method for preparing the reactive polyimide resin according to claim 6, characterized in that: In step (3), the post-processing includes: water washing and / or neutralization, desolventization, and filtration.

11. The method for preparing the reactive polyimide resin according to claim 6, characterized in that: In step (2), thermal imidization includes: heating the polyamic acid solution to 150-160°C and reacting for 2 hours to carry out the imidization reaction, and then heating it to 210-220°C and reacting for 3 hours to obtain the polyimide prepolymer.

12. The use of the reactive polyimide resin according to any one of claims 1-2 in the preparation of a curable resin composition.

13. The curable resin composition according to claim 12, characterized in that: The curable resin composition is a resin varnish with a solid content of 30-70%.

14. Use of the curable resin composition of claim 12 in the preparation of cured products, prepregs, laminated films and semiconductor sealing materials.

15. The use of the prepreg of claim 14 in the fabrication of a circuit board.

16. The use of the semiconductor sealing material of claim 14 in the fabrication of a semiconductor device.

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