A block-structured thermoplastic polyimide resin and its preparation method

Abstract

The present invention relates to a block-structured thermoplastic polyimide resin and a preparation method thereof, as well as a polyimide adhesive film and a polyimide composite copper foil composed of the block-structured thermoplastic polyimide resin. The polyimide adhesive film is formed by coating a polyimide base film with a mixture of a thermoplastic polyimide resin and a thermosetting polyimide resin. Among them, the thermoplastic resin is composed of a hard segment containing a benzimidazole or amide unit and a soft segment containing a flexible ether bond. This type of polyimide adhesive film composite copper foil is prepared by processing methods such as roll pressing and molding. The thermoplastic polyimide resin in the present invention has a soluble structure and does not require precursor processing, thus effectively suppressing the formation of bubbles. Moreover, an IPN interpenetrating network structure is formed between the thermoplastic resin and the thermosetting resin after curing, so that it has excellent mechanical properties, bonding properties and dimensional stability after being compounded with the copper foil, and thus can be applied to fields such as semiconductor packaging and flexible copper clad laminates.

Description

Technical Field

[0001] The present invention belongs to the field of functional materials, and particularly relates to a block-structured thermoplastic polyimide resin and a preparation method thereof. Background Art

[0002] Polyimide film composite copper foil has important applications in the preparation of flexible copper-clad laminates and semiconductor frame protective films. Key indicators such as the peel strength, flexural strength, and warpage between the two after composite are affected by the structure and properties of the adhesive layer on the surface of the polyimide film. Therefore, the development of the adhesive layer plays an important role in improving the comprehensive performance of such materials.

[0003] Currently, the widely used adhesive layer materials mainly include epoxy resin and thermoplastic polyimide resin. Epoxy resin is mainly used in the preparation of three-layer flexible copper-clad laminates (3L-FCCL), while thermoplastic polyimide resin is mainly applied to the preparation of two-layer flexible copper-clad laminates (2L-FCCL), that is, adhesive-free FCCL. Relatively speaking, 2L-FCCL is thinner and more flexible, so it has better application prospects. However, the thermoplastic polyimide resin currently used in 2L-FCCL is mostly processed using a polyamic acid precursor and needs to undergo processes such as high-temperature imidization. The small molecules of water and residual solvents released during the imidization reaction will cause stress concentration, affecting the bonding strength and dimensional stability. For example, the invention patent with the application number 202010136338.5 discloses a method for preparing an adhesive-free single-sided board by sequentially laminating a thermoplastic polyimide resin precursor (i.e., polyamic acid) and a thermosetting polyimide resin precursor. During the molding process, both resins need to undergo a high-temperature imidization reaction at 350 - 400 °C. The invention patent with the application number 202410829219.6 discloses a method for preparing a flexible copper-clad laminate through two imidization processes, and the second imidization needs to be carried out under harsh oxygen-free conditions, with a thermal imidization reaction time of 20 - 60 min. Therefore, how to directly synthesize a soluble thermoplastic PI resin through structural design and ensure excellent dimensional stability of the resin layer in the polyimide film and excellent bonding performance between the polyimide base film and the copper foil is of great significance for the development of new FCCL or semiconductor frame protective films. Summary of the Invention

[0004] Aiming at the defects of the prior art, the technical problem to be solved by the present invention is to provide a preparation method for a polyimide film composite copper foil with high bonding strength, high dimensional stability, and other comprehensive properties.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, a block-structured thermoplastic polyimide resin is obtained by successively polymerizing a dianhydride monomer Ar with a diamine monomer R1 and a diamine monomer R2. The general structural formula of the resin is as follows:

[0007] ;

[0008] Among them, the dianhydride monomer Ar is one of the following dianhydrides:

[0009] ;

[0010] The diamine monomer R1 is one of the following diamines:

[0011] ;

[0012] The diamine monomer R2 is one of the following diamines:

[0013] ;

[0014] Among them, for the block-structured thermoplastic polyimide resin, m = 2 - 8 and n = 2 - 8.

[0015] Preferably, the block-structured thermoplastic resin is composed of a hard segment containing a benzimidazole or amide unit and a soft segment containing a flexible ether bond, and the molar fraction ratio of the hard segment is (30 - 50) mol%.

[0016] In a second aspect, a method for preparing a block-structured thermoplastic polyimide resin includes: dissolving the diamine monomers R1 and R2 in a solvent and reacting them with the dianhydride monomer Ar in batches;

[0017] Among them, the solvent is selected from one or a combination of N,N-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), or γ-butyrolactone.

[0018] Preferably, the molar ratio of the diamine / dianhydride monomer of the diamine monomer R1 to the dianhydride monomer Ar is (m + 1) / m.

[0019] Preferably, the molar ratio of the diamine / dianhydride monomer of the diamine monomer R2 to the dianhydride monomer Ar is n / (n + 1).

[0020] Preferably, the process of dissolving the diamine monomers R1 and R2 in the solvent and the reaction process are protected with nitrogen or an inert gas.

[0021] Further, the specific steps of the preparation method include: S1. Under nitrogen protection, dissolve the diamine monomer R1 in a solvent, stir at room temperature, and after complete dissolution, add the dianhydride monomer Ar, control the molar ratio of diamine / dianhydride monomer to be (m + 1) / m, the reaction temperature to be (0 - 5)°C, the reaction time to be (6 - 12) h, then raise the reaction temperature to (160 - 170)°C and react for (6 - 10) h to synthesize the amine-terminated polyimide resin I;

[0022] S2. Under nitrogen protection, dissolve the diamine monomer R2 in a solvent, stir at room temperature, and after complete dissolution, add the dianhydride monomer Ar, control the molar ratio of diamine / dianhydride monomer to be n / (n + 1), the reaction temperature to be (0 - 5)°C, react for (6 - 12) h, then raise the reaction temperature to (160 - 170)°C and react for (6 - 10) h to synthesize the acid anhydride-terminated polyimide resin II;

[0023] S3. Under nitrogen protection, mix resin I and resin II, control the reaction temperature at (0 - 20)°C and react fully for (6 - 12) h to obtain a viscous thermoplastic polyimide resin, and obtain the block-structured thermoplastic polyimide resin as described above after curing, filtering, and defoaming.

[0024] In a third aspect, a resin composition includes: the block-structured thermoplastic polyimide resin and a thermosetting polyimide resin as described above, wherein the thermosetting resin is selected from any one or a combination of two of bismaleimide resin or PMR-type polyimide resin.

[0025] Preferably, the mass fraction of the thermosetting polyimide resin in the resin composition is (10 - 20) wt%.

[0026] Preferably, the resin composition further includes a solvent, and the solvent is selected from one or a combination of N, N-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), or γ-butyrolactone.

[0027] Preferably, the solid content of the resin composition is (10 - 15) wt%.

[0028] Preferably, the viscosity of the resin composition at 30°C is 1500 - 3000 centipoise.

[0029] In a fourth aspect, a preparation method of the resin composition as described above includes: fully mixing the block-structured thermoplastic polyimide resin and the thermosetting polyimide resin.

[0030] Preferably, the preparation method further includes: fully mixing the block-structured thermoplastic polyimide resin and the thermosetting polyimide resin by mechanical stirring.

[0031] Further, the block-structured thermoplastic polyimide resin and the thermosetting polyimide resin are fully mixed, then filtered and degassed for later use.

[0032] In a fifth aspect, a polyimide adhesive film is obtained by casting and extruding the above-mentioned resin composition onto the surface of a polyimide base film, followed by baking and drying.

[0033] Preferably, the coating amount of the resin composition in the polyimide adhesive film is (3 - 8) wt%.

[0034] Preferably, the baking temperature is 120 - 180 °C.

[0035] Preferably, the coating thickness of the resin composition layer is controlled to be 3 - 8 μm by adjusting the roll speed and the extrusion amount.

[0036] In a sixth aspect, a polyimide adhesive film composite copper foil is obtained by laminating the above-mentioned polyimide adhesive film and copper foil through roll pressing.

[0037] Preferably, the copper foil is first pretreated on the surface with a dilute alkali solution, and then the above-mentioned polyimide adhesive film and copper foil are laminated through roll pressing to obtain the polyimide adhesive film composite copper foil.

[0038] Preferably, the dilute alkali solution is selected from one of KOH, NaOH or ammonia water, with a concentration of 0.3 - 1.0 M, a pretreatment time of 1 - 3 min, and a temperature of 30 - 50 °C.

[0039] Preferably, the temperature of roll pressing is 300 - 400 °C, the pressure of roll pressing is 0.5 - 1.0 kN, and the rate of roll pressing is 1.0 - 1.5 m / min.

[0040] The beneficial effects achieved by the technical solution of the present invention are as follows:

[0041] Through structural design, the present invention synthesizes a block-structured thermoplastic polyimide resin with a certain degree of polymerization by using monomers containing rigid units such as benzimidazole and amide and flexible units such as ether bonds. Solvents such as N-methyl-pyrrolidone and N,N-dimethylacetamide can dissolve the thermoplastic polyimide resin, avoiding the complex high-temperature imidization reaction and its by-product water after compounding with the copper foil, and reducing the bubble rate during the compounding process.

[0042] Abundant hydrogen bond networks can be formed between benzimidazole and amide units in the synthesized thermoplastic resin, thereby endowing the resin composition system with excellent adhesion characteristics.

[0043] The microphase separation structure formed in the block-structured thermoplastic polyimide resin endows the resin with good melting and softening behavior, so that it can be better compounded with the copper foil and the polyimide base film.

[0044] A block structure thermoplastic polyimide and a thermosetting polyimide resin are selected and mixed to form a resin composition, which is used as a bonding layer. The interpenetrating network structure formed after curing restricts the molecular chain movement of the thermoplastic resin, thereby endowing the composite structure with excellent dimensional stability. Description of the Drawings

[0045] Figure 1 Schematic diagram of the structure of a polyimide adhesive film composite copper foil. Detailed Embodiments

[0046] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0047] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used here, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0048] If the specific experimental conditions are not specified in the embodiments, they are usually in accordance with the conventional conditions in the art or the conditions recommended by the reagent company; the materials, reagents, etc. used in the embodiments, unless otherwise specified, can be obtained through commercial channels.

[0049] The above polyimide monomers are provided by Tianjin Zhongtai Material Technology Co., Ltd.; the solvents are provided by Sinopharm Group; the polyimide base films are purchased from SKC Kolon Co., Ltd. of South Korea; the thermosetting polyimide resin is provided by Sanhua Electronic Insulating Materials Co., Ltd.

[0050] The bonding strength is tested by the 90° peel strength test method of IPC-TM-650 2.4.9, the dimensional stability is measured by the test method of IPC-TM-650 2.2.4, and the tensile strength is measured by a universal material testing machine with a tensile rate of 5 mm / min.

[0051] Example 1

[0052] Under nitrogen protection, the diamine monomer 2-(4-aminophenyl)-5-aminobenzimidazole (4,5-BIA) was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer 4,4'-oxydiphthalic anhydride (ODPA) was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 3. The reaction temperature was 5 °C and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and the reaction was carried out for 10 h to synthesize the amine-terminated polyimide resin I. Similarly, under nitrogen protection, the diamine monomer 3,4'-diaminodiphenyl ether (3,4-ODA) was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 3 / 4. The reaction temperature was 5 °C and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and the reaction was carried out for 10 h to synthesize the acid anhydride-terminated polyimide resin II. Resin I and resin II were mixed in an equimolar ratio and reacted fully at 20 °C under nitrogen protection for 12 h to obtain a viscous thermoplastic polyimide resin, which was used after sufficient curing, filtration, and degassing. The synthesized thermoplastic polyimide resin was mixed with a bismaleimide resin, and the content of the thermosetting resin was controlled to be 15 wt%. After complete mixing, it was degassed for use. The mixed resin was uniformly extruded and coated on a polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. A copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide adhesive film at 350 °C and a pressure of 1.0 kN to obtain a composite copper foil product.

[0053] Example 2

[0054] Under nitrogen protection, the diamine monomer 2-(3-aminophenyl)-5-aminobenzimidazole (3, 5-BIA) was dissolved in NMP and stirred at room temperature. After it was completely dissolved, the dianhydride monomer 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride (6FDA) was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 3. The reaction temperature was 5 ℃, and the reaction was carried out for 12 h. The reaction temperature was then increased to 170 ℃ for 10 h to synthesize the polyimide resin I terminated with an amine group. Similarly, under nitrogen protection, the diamine monomer APB was dissolved in NMP and stirred at room temperature. After it was completely dissolved, the dianhydride monomer 6FDA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 3 / 4. The reaction temperature was 5 ℃, and the reaction was carried out for 12 h. The reaction temperature was then increased to 170 ℃ for 10 h to synthesize the polyimide resin II terminated with anhydride. Resin I and resin II were mixed in equal molar ratios, and the reaction temperature was controlled at 20 ℃ under nitrogen protection for 12 h to obtain a viscous thermoplastic polyimide resin, which was fully matured, filtered, and degassed for use. The synthesized thermoplastic polyimide resin was mixed with bismaleimide resin, and the content of thermosetting resin was controlled to be 15 wt%. After complete mixing, the mixture was degassed and set aside. The mixed resin was uniformly extruded and coated on the polyimide base film by casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was compounded with the polyimide film at 350 ℃ and 1.0 kN pressure to obtain a composite copper foil product.

[0055] Example 3

[0056] Under nitrogen protection, the diamine monomer 4,4'-diaminobenzanilide (DABA) was dissolved in γ-butyrolactone, stirred at room temperature, and after it was completely dissolved, the dianhydride monomer BTDA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 5 / 4, the reaction temperature was 0 ℃, the reaction was carried out for 12 h, and then the reaction temperature was increased to 170 ℃ for 10 h to synthesize the polyimide resin I terminated with an amine group. Similarly, under nitrogen protection, the diamine monomer APB was dissolved in γ-butyrolactone, stirred at room temperature, and after it was completely dissolved, the dianhydride monomer BTDA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 5, the reaction temperature was 5 ℃, the reaction was carried out for 12 h, and then the reaction temperature was increased to 170 ℃ for 10 h to synthesize the polyimide resin II terminated with anhydride. Resin I and resin II were mixed in equal molar ratios and reacted for 12 h under nitrogen protection at a reaction temperature of 20 ℃ to obtain a viscous thermoplastic polyimide resin, which was fully matured, filtered, and degassed for use. The synthesized thermoplastic polyimide resin was mixed with bismaleimide resin, and the content of thermosetting resin was controlled to be 10 wt%. After complete mixing, the mixture was degassed and set aside. The mixed resin was uniformly extruded and coated on the polyimide base film by a casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was compounded with the polyimide film at 350 ℃ and 1.0 kN pressure to obtain a composite copper foil product.

[0057] Example 4

[0058] Under nitrogen protection, the diamine monomer 4,5-BIA was dissolved in NMP, stirred at room temperature, and after it was completely dissolved, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 3, the reaction temperature was 5 ℃, the reaction was carried out for 12 h, and the reaction temperature was increased to 170 ℃ for 10 h to synthesize the polyimide resin I terminated with an amine group. Similarly, under nitrogen protection, the diamine monomer 3, 4-ODA was dissolved in NMP, stirred at room temperature, and after it was completely dissolved, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 3 / 4, the reaction temperature was 5 ℃, the reaction was carried out for 12 h, and the reaction temperature was increased to 170 ℃ for 10 h to synthesize the polyimide resin II terminated with anhydride. Resin I and resin II were mixed in equal molar ratios, and the reaction temperature was controlled at 20 ℃ under nitrogen protection for 12 h to obtain a viscous thermoplastic polyimide resin, which was fully matured, filtered, and degassed for use. The synthesized thermoplastic polyimide resin was mixed with the PMR polyimide resin, and the content of the thermosetting resin was controlled to be 10 wt%. After the mixture was completely mixed, the mixture was degassed and set aside. The mixed resin was uniformly extruded and coated on the polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.5 M KOH for 3 min was compounded with the polyimide film at 350 ℃ and 1.0 kN pressure to obtain a composite copper foil product.

[0059] Comparative Example 1

[0060] Under nitrogen protection, the diamine monomer 4,5-BIA was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 1 / 1. The reaction temperature was 5 °C, and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and reacted for 10 h to synthesize the polyimide resin. After sufficient curing, filtration, and degassing, it was reserved for use. The synthesized polyimide resin was mixed with the bismaleimide resin, and the content of the thermosetting resin was controlled to be 15 wt%. After complete mixing, it was degassed and reserved for use. The mixed resin was uniformly extruded and coated on the polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide film at 350 °C and a pressure of 1.0 kN to obtain the composite copper foil product.

[0061] Comparative Example 2

[0062] Under nitrogen protection, the diamine monomer 3,4'-diaminodiphenyl ether (3,4-ODA) was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 1 / 1. The reaction temperature was 5 °C, and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and reacted for 10 h to synthesize the thermoplastic polyimide resin. After sufficient curing, filtration, and degassing, it was reserved for use. The synthesized thermoplastic polyimide resin was mixed with the bismaleimide resin, and the content of the thermosetting resin was controlled to be 15 wt%. After complete mixing, it was degassed and reserved for use. The mixed resin was uniformly extruded and coated on the polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide film at 350 °C and a pressure of 1.0 kN to obtain the composite copper foil product.

[0063] Comparative Example 3

[0064] Under nitrogen protection, the diamine monomer 4,5-BIA was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 3. The reaction temperature was 5 °C, and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and reacted for 10 h to synthesize the amino-terminated polyimide resin I. Similarly, under nitrogen protection, the diamine monomer 3,4-ODA was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 3 / 4. The reaction temperature was 5 °C, and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and reacted for 10 h to synthesize the anhydride-terminated polyimide resin II. The resin I and resin II were mixed in an equimolar ratio and reacted fully at 20 °C under nitrogen protection for 12 h to obtain a viscous thermoplastic polyimide resin. After sufficient curing, filtration, and degassing, it was reserved for use. The synthesized resin was uniformly extruded and coated on a polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide adhesive film at 350 °C and a pressure of 1.0 kN to obtain the composite copper foil product.

[0065] Comparative Example 4

[0066] Under nitrogen protection, equimolar amounts of the diamine monomers 4,5-BIA and 3,4-ODA were dissolved in NMP and stirred at room temperature. After complete dissolution, an equimolar amount of the dianhydride monomer ODPA was added relative to the diamine. The reaction temperature was 5 °C, and the reaction was carried out for 12 h. Then the reaction temperature was raised to 170 °C and reacted for 10 h to obtain a random copolymer thermoplastic polyimide resin. After sufficient curing, filtration, and degassing, it was reserved for use. The synthesized thermoplastic polyimide resin was mixed with a bismaleimide resin, and the content of the thermosetting resin was controlled to be 15 wt%. After complete mixing, it was degassed and reserved for use. The mixed resin was uniformly extruded and coated on a polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. The copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide adhesive film at 350 °C and a pressure of 1.0 kN to obtain the composite copper foil product.

[0067] Comparative Example 5

[0068] Under nitrogen protection, the diamine monomer 4, 5-BIA was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 4 / 3. The reaction temperature was 5 °C, and the reaction was carried out for 12 h to synthesize the amine-terminated polyamic acid resin I. Similarly, under nitrogen protection, the diamine monomer 3, 4-ODA was dissolved in NMP and stirred at room temperature. After complete dissolution, the dianhydride monomer ODPA was added, and the molar ratio of diamine / dianhydride monomer was controlled to be 3 / 4. The reaction temperature was 5 °C, and the reaction was carried out for 12 h to synthesize the acid anhydride-terminated polyamic acid resin II. Resin I and resin II were mixed in an equimolar ratio and reacted fully for 12 h under nitrogen protection at a reaction temperature of 20 °C to obtain a viscous thermoplastic polyamic acid resin. After sufficient curing, filtration, and degassing, it was ready for use. The synthesized thermoplastic polyamic acid resin was mixed with a bismaleimide resin, and the content of the thermosetting resin was controlled to be 15 wt%. After complete mixing, it was degassed and ready for use. The mixed resin was uniformly extruded and coated on a polyimide base film by the casting method, and the thickness of the resin layer was controlled to be 5 μm. A copper foil treated with 0.3 M NaOH for 1 min was laminated with the polyimide adhesive film at 350 °C and a pressure of 1.0 kN, and further imidized at 350 °C for 30 min to obtain a composite copper foil product.

[0069] The properties of the polyimide adhesive film composite copper foils prepared in Examples 1-4 and Comparative Examples 1-5 are listed in Table 1.

[0070] Table 1

[0071]

[0072] From the data analysis in Table 1, it can be seen that the polyimide adhesive film composite copper foils prepared in Examples 1-4 have a low bubble rate, high adhesion and dimensional stability, and good mechanical properties. Compared with Example 1, the thermoplastic polyimide resin synthesized in Comparative Example 1 does not contain a soft segment with a flexible ether bond. Therefore, the softening effect after heating is not good, the adhesion to the copper foil is low, and the tensile mechanical properties are directly lower than those of Example 1; in Comparative Example 2, the thermoplastic resin is only composed of a soft segment containing an ether bond and lacks a hydrogen bond network structure, resulting in low peel strength and tensile strength and poor dimensional stability; in Comparative Example 3, no thermosetting polyimide resin was added, and an interpenetrating network could not be formed. Therefore, the tensile strength and dimensional stability of Comparative Example 3 are lower than those of Example 1; in Comparative Example 4, a thermoplastic resin with a random copolymer structure was synthesized. Due to the lack of a microphase separation structure, it is difficult for the resin to soften upon heating, the bonding with the copper foil is poor, and the peel strength is low; in Comparative Example 5, the precursor polyamic acid of the thermoplastic polyimide resin was used for processing, and an imidization reaction would occur synchronously during the lamination with the copper foil, releasing by-products. Therefore, the bubble rate of the polyimide adhesive film composite copper foil prepared in Comparative Example 5 is significantly higher.

[0073] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of them. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. Although the specific implementation manners of the present invention have been described above, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A block structure thermoplastic polyimide resin, characterized in that: The block structure thermoplastic polyimide resin is obtained by sequentially polymerizing a dianhydride monomer Ar with a diamine monomer R1 and a diamine monomer R2. The general structural formula of the resin is shown below: ； Wherein, the dianhydride monomer Ar is one of the following dianhydrides: ； The diamine monomer R1 is one of the following diamines: ； The diamine monomer R2 is one of the following diamines: ； The block structure thermoplastic polyimide resin has m=2-8 and n=2-8; The block structure thermoplastic resin is composed of a hard segment containing benzimidazole or amide units and a soft segment containing flexible ether bonds, wherein the molar fraction ratio of the hard segment is (30-50) mol%; The solvent is selected from one or more combinations of N,N-dimethylacetamide, N-methyl-pyrrolidone or γ-butyrolactone; The method for preparing the block structure thermoplastic polyimide resin comprises: dissolving the diamine monomer R1 and the diamine monomer R2 in a solvent, and reacting them with the dianhydride monomer Ar in batches; The molar ratio of the diamine monomer R1 to the diamine monomer Ar is (m+1) / m; the molar ratio of the diamine monomer R2 to the diamine monomer Ar is n / (n+1); The preparation method comprises the following specific steps: S1, under nitrogen protection, dissolving the diamine monomer R1 in a solvent, stirring at room temperature, adding the dianhydride monomer Ar after it is completely dissolved, and controlling the molar ratio of the diamine / dianhydride monomer to be (m+1) / m, the reaction temperature to be (0-5)°C, the reaction time to be (6-12)h, and then raising the reaction temperature to (160-170)°C and reacting for (6-10)h to synthesize the polyimide resin I terminated with an amino group; S2. Under nitrogen protection, dissolve the diamine monomer R2 in a solvent, stir at room temperature, add the dianhydride monomer Ar after it is completely dissolved, and control the molar ratio of diamine / dianhydride monomer to be n / (n+1), the reaction temperature is (0-5)°C, react for (6-12) hours, and then increase the reaction temperature to (160-170)°C and react for (6-10) hours to synthesize the polyimide resin II terminated with anhydride; S3. Resin I and resin II are mixed under nitrogen protection, and the reaction temperature is controlled to be (0-20) °C for sufficient reaction for (6-12) h to obtain a viscous thermoplastic polyimide resin. After aging, filtering and degassing, the above-mentioned block structure thermoplastic polyimide resin is obtained.

2. A resin composition comprising: The block structure thermoplastic polyimide resin and thermosetting polyimide resin according to claim 1, wherein the thermosetting resin is selected from any one of bismaleimide resin and PMR type polyimide resin or a combination of two thereof.

3. The resin composition according to claim 2, characterized in that The mass fraction of the thermosetting polyimide resin in the resin composition is (10-20) wt%.

4. The method for preparing the resin composition according to any one of claims 2 to 3, characterized in that: The preparation method comprises: fully mixing the block structure thermoplastic polyimide resin and the thermosetting polyimide resin according to claim 1.

5. A polyimide film, characterized in that: The resin composition according to any one of claims 2 to 3 is coated on the surface of a polyimide base film by a cast extrusion method, and then baked and dried to obtain the polyimide adhesive film.

6. A polyimide film composite copper foil, characterized in that: The polyimide adhesive film according to claim 5 is compounded with copper foil by rolling.

7. The polyimide adhesive film composite copper foil according to claim 6, characterized in that: The rolling temperature is 300-400°C, the rolling pressure is 0.5-1.0 kN, and the rolling speed is 1.0-1.5 m / min.

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