Block polyimide resin, and preparation method therefor and use thereof

Abstract

Disclosed are a block polyimide resin, and a preparation method therefor and a use thereof. The molecular backbone of the block polyimide resin comprises hard segment units and soft segment units which are alternately distributed, wherein the soft segment units contain a relatively large number of flexible groups and have a relatively low glass transition temperature, and the hard segment units contain a relatively large number of rigid conjugated groups and a relatively high glass transition temperature. When the soft segment units transition to a rubbery state as the temperature increases, the hard segment units remain in a glassy state, so that the block polyimide resin can still maintain certain mechanical strength while having a relatively good melt bonding capability, resulting in improved processability. In addition, the thermal stability, mechanical properties, and dimensional stability of the block polyimide resin are all relatively good. The block polyimide resin has good application prospects.

Description

A block polyimide resin, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 2024115613492, filed on November 4, 2024, entitled "A Block Polyimide Resin and Its Preparation Method and Application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of polymers, and specifically relates to a block polyimide resin, its preparation method, and its application. Background Technology

[0003] Flexible copper clad laminates (CCLs) are the substrate of printed circuit boards (PCBs) and an indispensable basic material in the electronics industry. Based on material type and structure, they can be divided into adhesive-bonded flexible CCLs and adhesive-free flexible CCLs, with adhesive-free flexible CCLs exhibiting superior performance.

[0004] There are three main production methods for adhesive-free flexible copper-clad laminates: coating, lamination, and sputtering electroplating. Among these, the lamination and coating methods require thermoplastic polyimide for producing adhesive-free double-sided products. The main chain of thermoplastic polyimide contains many flexible groups, giving the molecular chain segments high mobility and a low glass transition temperature. However, these flexible groups can also lead to a decrease in mechanical properties. In applications, thermoplastic polyimide resin is coated on both sides of a conventional polyimide film. The conventional polyimide film has excellent mechanical properties and dimensional stability, which can neutralize the negative impact of the reduced mechanical properties caused by the thermoplastic polyimide resin. However, this also places more stringent requirements on the performance of the conventional polyimide film and the thickness and precision of the thermoplastic polyimide. CN114989605A discloses a polyimide resin with a low coefficient of thermal expansion. By mixing thermoplastic polyimide resin and conventional polyimide resin in a certain proportion, the resulting mixed resin can maintain excellent melt processing performance while having a low coefficient of thermal expansion and also achieving good optical properties. While improvements have been made to the resin in terms of processing performance, coefficient of thermal expansion, and optical properties, the mechanical properties, heat resistance, and dimensional stability of the resin have not been addressed.

[0005] Therefore, it is of great significance to develop a polyimide resin with good melt processing properties, mechanical properties, heat resistance and dimensional stability. Summary of the Invention

[0006] To address the deficiencies in existing technologies, this application provides a block polyimide resin, its preparation method, and its applications. The molecular backbone of the block polyimide resin of this application includes alternating hard segment units and soft segment units. The soft segment units contain more flexible groups and have a lower glass transition temperature, while the hard segment units contain more rigid conjugated groups and have a higher glass transition temperature. The alternating distribution of hard and soft segment units enables the block polyimide resin to possess a suitable glass transition temperature. When the temperature increases, the soft segment units become elastic, while the hard segment units remain in the glassy state. The elastic state is beneficial for maintaining good melt bonding ability of the resin, while the glassy state is beneficial for maintaining good mechanical properties, heat resistance, and dimensional stability of the resin.

[0007] This application provides a block polyimide resin, wherein the molecular backbone of the block polyimide resin comprises alternating hard segment units and soft segment units, the hard segment units having the structure shown in Formula I, and the soft segment units having the structure shown in Formula II.

[0008] In Equation I, 5 ≤ x ≤ 25, and Ar1 is selected from... and / or Ar2 is selected from One or more of the following, wherein R1 is selected from H, C1-C3 alkyl or trifluoromethyl, and L1 is selected from single bond, ether bond or -C(O)NH-;

[0009] In Equation II, 5 ≤ y ≤ 25, and B is selected from... One or more of the following, wherein R2 is selected from H, C1-C3 alkyl or trifluoromethyl, R3 and R4 are each independently selected from H or methyl, and L2 is selected from ether bond, -C(R5R6)-, -C(O)-, One or more of them, wherein R5 and R6 are each independently selected from H, C1-C3 alkyl or trifluoromethyl;

[0010] A is selected from One or more of 1,6-hexene; z is 32-34, and L3, L4, and L5 are each independently selected from ether bonds, methylene groups, -C(O)-, -S(O2)-, R7 and R8 are each independently selected from H, methyl, or trifluoromethyl.

[0011] In one alternative embodiment, the degree of polymerization of the molecular backbone is ≥50.

[0012] In one alternative embodiment, the degree of polymerization of the molecular backbone is 100 to 200.

[0013] In one alternative embodiment, the number of polymeric units in the soft segment unit accounts for 30% to 70% of the total number of polymeric units in the molecular backbone.

[0014] In one optional embodiment, the glass transition temperature of the block polyimide resin is 200–300°C; and / or, the thermal decomposition temperature of the block polyimide resin is ≥450°C.

[0015] In one alternative implementation, the following steps are included:

[0016] 1) Preparation of polyimide resin solutions with hard segment units or soft segment units

[0017] Under an inert atmosphere, diamine compound N1 is dissolved in a solvent, and dianhydride compound G1 is added to it. The reaction is carried out at 5–45°C for 4–48 h to obtain a hard-segment or soft-segment polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain an amino-terminated hard-segment or soft-segment polyimide resin solution.

[0018] 2) Preparation of block polyimide resin

[0019] Under an inert atmosphere, a diamine compound N2 is added to the amino-terminated hard-segment or soft-segment polyimide resin solution prepared in step 1) and dissolved. Then, a dianhydride compound G2 is added, and the reaction is carried out at 5–45°C for 4–48 h to obtain a block polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain the block polyimide resin solution. Alternatively, the block polyamic acid solution is heat-treated at 300–400°C to obtain the block polyimide resin.

[0020] The diamine compound N1 and the diamine compound N2 are different and have structures of Formula 1 and Formula 2, respectively: H2N-Ar2-NH2 (Formula 1); H2N-A-NH2 (Formula 2);

[0021] The dianhydride compounds G1 and G2 are different and have structures of Formula 3 and Formula 4, respectively:

[0022] When the diamine compound N1 has the structure shown in Formula 1, the dianhydride compound G1 has the structure shown in Formula 3; when the diamine compound N2 has the structure shown in Formula 2, the dianhydride compound G2 has the structure shown in Formula 4.

[0023] In one optional embodiment, the dianhydride compound G1 and / or the dianhydride compound G2 are added to the reaction system in three portions at amounts of 60 wt%, 30 wt%, and 10 wt%, respectively.

[0024] In one optional embodiment, in step 1), the solid content of the polyamic acid solution of the hard segment unit or soft segment unit is 5% to 15%.

[0025] And / or, in step 2), the solid content of the block polyamic acid solution is 10% to 25%.

[0026] In one alternative embodiment, the block polyimide resin described above is included.

[0027] In one optional embodiment, the film has a tensile strength ≥150MPa, an elongation at break ≥20%, a linear coefficient of thermal expansion of 15~40ppm / K, and an absolute value of dimensional stability ≤0.15%.

[0028] In one alternative embodiment, the block polyimide film is included, along with a copper foil laminated to one or both surfaces of the block polyimide film.

[0029] In one alternative implementation, the flexible copper-clad laminate is used in the field of printed circuit boards.

[0030] The implementation of this application has at least the following advantages:

[0031] 1) The block polyimide resin provided in this application has hard segment units and soft segment units arranged alternately and orderly in its molecular chain. The soft segment units contain a large number of flexible groups such as ether groups, ester groups, methylene groups, and isopropylidene groups, and have a low glass transition temperature of 200-300℃. They can transform into a highly elastic state at temperatures of 250-350℃, exhibiting good melt bonding ability. Simultaneously, the hard segment units contain a large number of rigid conjugated groups, exhibiting high mechanical properties and a high glass transition temperature exceeding 320℃. When the temperature rises, the soft segment units transform into a highly elastic state, while the hard segment units remain in the glassy state, maintaining good mechanical properties, heat resistance, and dimensional stability.

[0032] 2) The block polyimide film provided in this application is prepared by coating a block polyimide resin that possesses both good melt bonding ability and good mechanical properties. It can be used for hot pressing to prepare film products. During hot pressing, conventional polyimide films are not required to provide mechanical strength, thus avoiding problems such as heat deformation and poor dimensional stability. Compared to commercially available "thermoplastic polyimide-conventional polyimide-thermoplastic polyimide" products that are composited with thermoplastic polyimide resin on conventional polyimide films, this simplifies the production process and equipment, reduces production difficulty and precision requirements, and has the potential advantages of improved yield and reduced production costs.

[0033] 3) The flexible copper-clad laminate prepared from block polyimide resin provided in this application is obtained by coating block polyimide resin onto copper foil and heat-treating it to form a film, or by processing block polyimide resin into a thin film product and then laminating it with copper foil. It can be prepared as a single-sided or double-sided flexible copper-clad laminate. During the production process, conventional polyimide resin or conventional polyimide film is not required to provide mechanical strength to neutralize the negative impact of reduced mechanical properties caused by thermoplastic polyimide resin. Compared to single-sided or double-sided flexible copper-clad laminates on the market that require the combination of thermoplastic polyimide and conventional polyimide, the flexible copper-clad laminate provided in this application has a simplified production process, fewer production steps, and potential advantages in improving yield and reducing production costs. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The application scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that with the emergence of new application scenarios, the technical solutions provided in this application are also applicable to similar technical problems. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0036] The first aspect of this application provides a block polyimide resin, wherein the molecular backbone of the block polyimide resin comprises alternating hard segment units and soft segment units, the hard segment units having the structure shown in Formula I, and the soft segment units having the structure shown in Formula II.

[0037] In Equation I, 5 ≤ x ≤ 25, and Ar1 is selected from... and / or Ar2 is selected from One or more of the following, wherein R1 is selected from H, C1-C3 alkyl or trifluoromethyl, and L1 is selected from single bond, ether bond or -C(O)NH-;

[0038] In Equation II, 5 ≤ y ≤ 25, and B is selected from... One or more of the following, wherein R2 is selected from H, C1-C3 alkyl or trifluoromethyl, R3 and R4 are each independently selected from H or methyl, and L2 is selected from ether bond, -C(R5R6)-, -C(O)-, One or more of them, wherein R5 and R6 are each independently selected from H, C1-C3 alkyl or trifluoromethyl;

[0039] A is selected from One or more of 1,6-hexene; z is 32-34, and L3, L4, and L5 are each independently selected from ether bonds, methylene groups, -C(O)-, -S(O2)-, R7 and R8 are each independently selected from H, methyl, or trifluoromethyl.

[0040] In this context, * indicates the location of the connection point between the molecule and other parts.

[0041] In the above substituents, the C1 to C3 alkyl groups refer to saturated hydrocarbon groups with 1 to 3 carbon atoms, specifically methyl, ethyl, n-propyl or isopropyl. When L1 is a single bond, it means that two benzene rings are directly connected by a single bond.

[0042] The block polyimide resin of this application comprises hard segment units and soft segment units in its molecular backbone. The soft segment units contain a large number of flexible groups such as ether groups, ester groups, methylene groups, and isopropylidene groups, with a glass transition temperature of 200–300°C, and can transform into a highly elastic state at temperatures of 250–350°C. The hard segment units contain more rigid conjugated groups, exhibiting better mechanical properties, and have a glass transition temperature exceeding 320°C. When the temperature increases, the soft segment units, due to their lower glass transition temperature, transform into the highly elastic state, while the hard segment units, due to their higher glass transition temperature, remain in the glassy state, thus maintaining the resin's good mechanical properties and preventing deformation.

[0043] The soft segment unit has the structure shown in Formula II. In Formula II, 5 ≤ y ≤ 25. The degree of polymerization of the soft segment unit directly affects the Young's modulus and bonding ability of the block polyimide resin. Excessive polymerization of the soft segment unit leads to a low Young's modulus, reduced tensile strength, and poor dimensional stability. Conversely, insufficient polymerization of the soft segment unit increases the melt viscosity of the block polyimide resin in the high-temperature viscoelastic state, resulting in poor bonding strength with other materials. Therefore, when designing block polyimide resins, the degree of polymerization of the soft segment unit must be rationally selected according to specific application requirements to achieve better overall performance. Based on the above considerations, the applicant limits y to the above range. For example, it can specifically be a range consisting of 5, 10, 15, 20, 25, or any two of the above values.

[0044] The hard segment unit has the structure shown in Formula I. In Formula I, 5 ≤ x ≤ 25. The degree of polymerization of the hard segment unit directly affects the high-temperature melt viscosity and bonding performance of the block polyimide resin. If the hard segment unit has a high degree of polymerization, the high-temperature melt viscosity and Young's modulus of the block polyimide resin are high, which will reduce the bonding strength with other materials. If the hard segment unit has a low degree of polymerization, the Young's modulus of the block polyimide resin will decrease, and the dimensional stability will deteriorate. Therefore, when designing block resins, it is necessary to reasonably select the degree of polymerization of the hard segment unit according to the specific application requirements to achieve the best comprehensive performance, such as high-temperature bonding ability. Based on the above considerations, the applicant limits x to the above range. For example, it can be a range consisting of 5, 10, 15, 20, 25, or any two of the above values.

[0045] In this design, hard segment units and soft segment units are alternately distributed. Hard segment units provide strength and rigidity, while soft segment units provide toughness and flexibility. This alternating distribution allows the polyimide resin to maintain high mechanical strength and Young's modulus while also exhibiting good bond strength and toughness, significantly improving the overall performance of block polyimide resins.

[0046] In one specific embodiment, the degree of polymerization of the molecular backbone is ≥50. The degree of polymerization refers to the number of structural units in a polymer molecular chain, representing the average number of repeating units contained in the polymer macromolecular chain. In this application, the degree of polymerization of the molecular backbone is the total number of repeating units. The total degree of polymerization of block polyimide resins has a significant impact on their physicochemical properties. When the total degree of polymerization is too low, the molecular chains are shorter, resulting in reduced mechanical properties such as tensile strength, Young's modulus, and toughness, as well as decreased thermal stability, leading to easy decomposition or deformation. Based on these considerations, the applicant has limited the total degree of polymerization to the above range.

[0047] In one specific embodiment, the degree of polymerization of the molecular backbone is 100–200. When the total degree of polymerization of the block polyimide resin is too high, the molecular chains are too long, the overall molecular weight is too high, the high-temperature melt viscosity is high, and the melt processing becomes difficult. When the total degree of polymerization is within the above range, the block polyimide resin has a suitable molecular weight range and possesses good melt processing performance, mechanical properties, heat resistance, and dimensional stability. For example, it can specifically be a range of any two values ​​from 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200.

[0048] In one specific embodiment, the number of polymeric units in the soft segment unit accounts for 30% to 70% of the total number of polymeric units on the molecular backbone. The number of polymeric units in the soft segment unit is the sum of the number of repeating units in each soft segment, while the number of polymeric units on the molecular backbone refers to the sum of the number of repeating units in each soft segment and each hard segment. Soft segment units contain a relatively large number of flexible groups such as ether groups, ester groups, methylene groups, and isopropylidene groups, and have a low glass transition temperature, providing flexibility. Their content significantly affects the mechanical properties of block polyimide resins. When the proportion of polymeric units in the soft segment unit is too low, the proportion of polymeric units in the hard segment unit is high, resulting in a high melt viscosity and high Young's modulus of the resin at high temperatures, making bonding and processing difficult and reducing the bonding strength with other materials. Conversely, when the proportion of polymeric units in the soft segment unit is too high, the proportion of polymeric units in the hard segment unit is low, resulting in a low Young's modulus of the block polyimide resin and poor dimensional stability. Based on these considerations, the proportion of polymeric units in the soft segment unit is limited to the above range. For example, it can be a range consisting of any two values ​​of 30%, 40%, 50%, 60%, 70%, or more.

[0049] In one specific embodiment, the glass transition temperature of the block polyimide resin is 200–300°C; and / or, the thermal decomposition temperature of the block polyimide resin is ≥450°C.

[0050] The glass transition temperature of the block polyimide resin in this application is 200–300°C. The glass transition temperature is the temperature at which a polymer transitions from a glassy state to a rubbery state, and it is an important parameter describing thermal properties. The block polyimide resin of this application includes soft segment units and hard segment units. The soft segment units have a lower glass transition temperature of 200–300°C, while the hard segment units have a higher glass transition temperature, greater than 320°C. Alternating between these soft and hard segment units prevents the melt viscosity of the block polyimide resin from becoming too low at high temperatures, allowing the resin to maintain good mechanical properties while possessing melt bonding ability, which is beneficial for processing.

[0051] The block polyimide resin of this application has a thermal decomposition temperature ≥450℃. This high thermal decomposition temperature indicates that the block polyimide resin exhibits good thermal stability at high temperatures, which helps extend its service life at high temperatures, effectively reduces performance degradation caused by thermal decomposition, and makes it suitable for various high-temperature environments.

[0052] A second aspect of this application provides a method for preparing a block polyimide resin, comprising the following steps:

[0053] 1) Preparation of polyimide resin solutions with hard segment units or soft segment units

[0054] Under an inert atmosphere, diamine compound N1 is dissolved in a solvent, and dianhydride compound G1 is added to it. The reaction is carried out at 5–45°C for 4–48 h to obtain a hard-segment or soft-segment polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain an amino-terminated hard-segment or soft-segment polyimide resin solution.

[0055] 2) Preparation of block polyimide resin

[0056] Under an inert atmosphere, a diamine compound N2 is added to the amino-terminated hard-segment or soft-segment polyimide resin solution prepared in step 1) and dissolved. Then, a dianhydride compound G2 is added, and the reaction is carried out at 5–45°C for 4–48 h to obtain a block polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain the block polyimide resin solution. Alternatively, the block polyamic acid solution is heat-treated at 300–400°C to obtain the block polyimide resin.

[0057] The diamine compound N1 and the diamine compound N2 are different and have structures of Formula 1 and Formula 2, respectively: H2N-Ar2-NH2 (Formula 1); H2N-A-NH2 (Formula 2);

[0058] The dianhydride compounds G1 and G2 are different and have structures of Formula 3 and Formula 4, respectively:

[0059] When the diamine compound N1 has the structure shown in Formula 1, the dianhydride compound G1 has the structure shown in Formula 3; when the diamine compound N2 has the structure shown in Formula 2, the dianhydride compound G2 has the structure shown in Formula 4.

[0060] Among them, diamine compounds N1 and N2 can be diamine compounds that synthesize hard segment units, as shown in Formula 1, or diamine compounds that synthesize soft segment units, as shown in Formula 2; dianhydride compounds G1 and G2 can be dianhydride compounds that synthesize hard segment units, as shown in Formula 3, or dianhydride compounds that synthesize soft segment units, as shown in Formula 4.

[0061] Wherein, when diamine compound N1 has the structure of Formula 1, dianhydride compound G1 has the structure of Formula 3, and in step 1), the hard segment unit polyamic acid solution is first synthesized, then diamine compound N2 has the structure of Formula 2, and dianhydride compound G2 has the structure of Formula 4; when diamine compound N1 has the structure of Formula 2, dianhydride compound G1 has the structure of Formula 4, and in step 1), the soft segment unit polyamic acid solution is first synthesized, then diamine compound N2 has the structure of Formula 1, and dianhydride compound G2 has the structure of Formula 3.

[0062] In one specific embodiment, the diamine compound with the structure shown in Formula 1 includes, but is not limited to, any one or more of p-phenylenediamine, m-phenylenediamine, benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzoylaniline, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, and 2,2'-bis(trifluoromethyl)diaminobiphenyl.

[0063] In one specific embodiment, the diamine compound with the structure shown in Formula 2 includes, but is not limited to, one or more of 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodibenzophenone, 4,4'-diaminodiphenyl sulfone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 1,3-bis(4'-aminophenoxy)benzene, 1,3-bis(3'-aminophenoxy)benzene, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 1,4-cyclohexanediamine, 1,6-hexanediamine, and polyetheramine D-2000.

[0064] In one specific embodiment, the dianhydride compound shown in Formula 3 can be pyromellitic dianhydride and / or 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

[0065] In one specific embodiment, the dianhydride compounds shown in Formula 4 include, but are not limited to, any one or more of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-terephthalodioxydiphthalic anhydride, bisphenol A type diether dianhydride, p-phenylene-bisphenyltriester dianhydride, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

[0066] In steps 1) and 2), the reaction temperature is 5 to 45°C. For example, it can be any two values ​​of 5°C, 15°C, 25°C, 35°C, 45°C or above. The reaction time is 4 to 48 hours. For example, it can be any two values ​​of 4 hours, 15 hours, 26 hours, 37 hours, 48 ​​hours or above.

[0067] Furthermore, in step 1), the solvent is a strongly polar solvent, specifically one or more of N-methylpyrrolidone, m-cresol, and γ-butyrolactone, mixed in any proportion. In the preparation of hard-segment or soft-segment polyamic acid solutions, using a strongly polar solvent and adjusting the type and proportion of the solvent can not only promote the dissolution of the reactants and the reaction, but also facilitate the dissolution of hard-segment or soft-segment polyimide resins and block polyimide resins. For example, by selecting a suitable strongly polar solvent, the solubility of hard-segment or soft-segment polyimide resins can be increased, which is beneficial for the polymerization reaction, as well as for increasing the solid content and reducing solvent usage costs.

[0068] In step 2), after obtaining the block polyamic acid solution, the block polyamic acid can be dehydrated by adding a dehydrating agent or by heat treatment to induce an imidization reaction, thereby obtaining a block polyimide resin. However, in step 1), heat treatment will cause the hard or soft segment polyimide resin solution to form a dry film, making it impossible to add the soft or hard segment units in step 2). Adding a dehydrating agent is more convenient for subsequent reactions.

[0069] Specifically, the dehydrating agent is one or both of toluene and xylene, mixed in any proportion. The amount of dehydrating agent added is 10% to 20% of the weight of the polyamic acid solution.

[0070] Specifically, the heat treatment temperature is 300–400℃. The heat treatment temperature affects the degree of imidization. If the heat treatment temperature is too low, the imidization reaction of polyamic acid to polyimide may be incomplete, resulting in residual polyamic acid. If the heat treatment temperature is too high, the polyimide resin may undergo thermal degradation, leading to molecular chain breakage and potentially reducing its performance. Based on these considerations, the heat treatment temperature is controlled within the above range. For example, it can be any combination of 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, or any two of the above values.

[0071] In one specific embodiment, dianhydride compound G1 and / or dianhydride compound G2 are added to the reaction system in three separate additions at amounts of 60 wt%, 30 wt%, and 10 wt%, respectively. During the addition of the dianhydride compounds in steps 1) and 2), 60 wt% of the dianhydride compound is added first, 30 wt% is added second, and 10 wt% is added third. This stepwise addition facilitates control of the polymerization reaction process, ensuring uniform polymer molecular chain segments and molecular weight.

[0072] In one specific embodiment, in step 1), the solid content of the polyamic acid solution of the hard segment unit or soft segment unit is 5% to 15%.

[0073] And / or, in step 2), the solid content of the block polyamic acid solution is 10% to 25%.

[0074] In step 1), the solid content is the ratio of the mass of the remaining solid portion to the total mass of the solution after drying under certain conditions. If the solid content is too high, the resulting hard or soft segment polyimide resin units will precipitate in the solution, making polymerization in step 2) impossible. If the solid content is too low, it will increase the amount of solvent used, resulting in increased costs. In step 2), the polyimide resin solution obtained in step 1) is added, without adding additional solvent to adjust the solid content. Its solid content is directly related to the solid content in step 1).

[0075] The third aspect of this application provides a block polyimide film comprising the block polyimide resin described in the first aspect, without limiting its preparation method.

[0076] In one specific embodiment, the preparation of a block polyimide film may include the following steps:

[0077] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of the second aspect of this application is coated on the carrier. The coating thickness is determined according to the solid content of the solution and the thickness requirement. After coating, the block polyamic acid dry film layer is obtained by solvent evaporation.

[0078] 2) Preparation of block polyimide film: In a nitrogen atmosphere, the carrier in step 1) is heat-treated, and the block polyamic acid dry film layer undergoes an imidization reaction to obtain a block polyimide film layer. The block polyimide film layer is then removed from the carrier to obtain a block polyimide film.

[0079] Specifically, in step 1), the solvent evaporation temperature is 80–150°C. The carrier coated with the block polyamic acid solution is placed in an oven to allow the solvent to evaporate, which aims to accelerate the drying process of the block polyamic acid solution and obtain a block polyamic acid dry film layer more quickly.

[0080] Specifically, the heat treatment temperature in step 2) is 300–400°C. The block polyamic acid dry film layer obtained in step 1) is placed in an oven to dehydrate and undergo an imidization reaction to obtain a block polyimide film layer.

[0081] Specifically, in step 1), the coating thickness of the block polyamic acid solution is 150–300 μm. If the coating thickness is too small, the resulting block polyimide film will be too thin and will not meet the sample preparation requirements; if the coating thickness is too large, the imidization reaction may be incomplete in step 2), making it difficult for the internal polyamic acid to be completely converted into polyimide, thus affecting the stability and mechanical properties of the film.

[0082] In step 1), the solvent content in the block polyamic acid dry film layer is between 15 and 25 wt%. After heating to evaporate the solvent component, its residual amount in the polyamic acid dry film layer is 15 to 25 wt%. A lower residual solvent amount requires a higher solvent evaporation temperature and a longer solvent evaporation time, which slows down the reaction process; a higher solvent participation will affect the subsequent heat treatment and imidization process, reducing the mechanical properties and thermal stability of the block polyimide resin.

[0083] In step 2), after obtaining the block polyimide film layer, it can be boiled in boiling water for a period of time to facilitate its peeling off from the carrier surface to obtain the block polyimide film.

[0084] In one specific embodiment, the film has a tensile strength ≥150MPa, an elongation at break ≥20%, a linear coefficient of thermal expansion of 15~40ppm / K, and an absolute value of dimensional stability ≤0.15%. Tensile strength is the maximum stress a material can withstand when stretched to break. The tensile strength of the film is ≥150MPa, indicating that the block polyimide film of this application can remain stable in a high-stress environment and is not prone to breakage or damage. Elongation at break refers to the change in length of the film from its initial length to the point of breakage during a tensile test. It reflects the maximum amount of deformation that the film can withstand during the stretching process. Elongation at break is ≥20%, indicating that the film of this application can adapt to large deformation and stress changes and is not prone to brittle fracture. The coefficient of linear thermal expansion directly reflects the dimensional change characteristics of the film under temperature changes. The coefficient of linear thermal expansion is 15~40ppm / K, indicating that the film of this application exhibits good thermal stability and dimensional stability in a temperature fluctuation environment. Dimensional stability is the percentage of dimensional change of the film under specific conditions. Dimensional stability is ≤0.15%, indicating that the dimensional change of the film of this application does not exceed 0.15%, indicating that its dimensional consistency before and after processing is high.

[0085] This application provides a flexible copper-clad laminate, comprising the block polyimide film as described in claim 9 or 10 and copper foil laminated to one or both surfaces of the block polyimide film. Flexible copper-clad laminates can be classified into single-sided flexible copper-clad laminates and double-sided flexible copper-clad laminates according to their product structure. Single-sided flexible copper-clad laminates have circuitry covered on only one side, suitable for simple circuit connection requirements; double-sided flexible copper-clad laminates have circuitry covered on both sides, suitable for complex circuit designs requiring electronic component connections on both sides. Block polyimide resin can be used to prepare flexible copper-clad laminates, which have better heat resistance, stability, bonding strength, and flexural strength, and can be made thinner.

[0086] This application does not limit the preparation method of flexible copper-clad laminates containing block polyimide resin.

[0087] In one specific embodiment, the preparation of a pressable single-sided flexible copper-clad laminate sample may include the following steps:

[0088] The block polyamic acid solution obtained in step 2) of the second aspect of this application is coated onto a copper foil carrier. The coating thickness is determined according to the solid content of the solution and the thickness requirements. After coating, the solution is volatilized to obtain a block polyamic acid dry film layer. In a nitrogen atmosphere, the copper foil carrier coated with the block polyamic acid dry film layer is heat-treated to undergo an imidization reaction to obtain a copper foil sample coated with a block polyimide film layer, which can then be laminated into a single-sided flexible copper clad laminate sample.

[0089] In one specific embodiment, the preparation of a double-sided flexible copper clad laminate sample may include the following steps: bonding the above-obtained pressable single-sided flexible copper clad laminate sample with a copper foil sample, and hot-pressing them under nitrogen protection to obtain a double-sided flexible copper clad laminate sample.

[0090] In one specific embodiment, the preparation of a double-sided flexible copper clad laminate sample may include the following steps: bonding the above-obtained pressable single-sided flexible copper clad laminate sample with another pressable single-sided flexible copper clad laminate sample, and hot-pressing them under nitrogen protection to obtain a double-sided flexible copper clad laminate sample.

[0091] Specifically, the coating thickness, evaporation temperature, and solvent content of the aforementioned block polyamic acid solution can be referenced to step 1) of the preparation process of the block polyimide film provided in the third aspect; the heat treatment temperature can be referenced to step 2) of the preparation process of the block polyimide film provided in the third aspect.

[0092] Specifically, the hot pressing process can be carried out on a high-temperature roller press or a high-temperature flat plate press.

[0093] Specifically, the hot pressing temperature is 250–350℃. Controlling the temperature within this range will result in a better hot pressing effect.

[0094] The fifth aspect of this application provides an application of flexible copper-clad laminate in the field of printed circuit boards (PCBs). Because the block-type polyimide resin of this application possesses good mechanical properties, heat resistance, and dimensional stability, using a flexible copper-clad laminate containing this block-type polyimide resin as a PCB material results in PCBs with good fatigue resistance and durability, as well as good stability and reliability in high-temperature environments. By selecting resin materials with excellent mechanical properties, heat resistance, and dimensional stability, the overall performance and application value of PCBs can be significantly improved, meeting the demands of modern electronic products for high performance and reliability.

[0095] The following will further introduce a block polyimide resin, its preparation method, and its applications with specific embodiments.

[0096] Unless otherwise specified, the experimental methods used in the following embodiments can be conventional methods in the art.

[0097] In the following embodiments, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0098] The raw material information used in the embodiments and comparative examples of this application is shown in Table 1 below:

[0099] Table 1

[0100] Example 1

[0101] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0102] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0103] Add 15g of toluene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 12h, so that the water generated in the reaction is carried out by the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0104] 2) Preparation of block polyimide resin: Under a nitrogen atmosphere, 0.15 g of 4,4'-ODA and 2.03 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds. 2.79 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0105] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0106] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 300 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0107] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0108] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0109] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 300 μm. Then, it is placed at 150°C. After the solvent evaporates, a copper foil sample coated with a dry polyamic acid film layer is obtained. The content of strong polar solvent is 15 wt%.

[0110] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0111] 3) Preparation of the double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 278℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0112] Example 2

[0113] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0114] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0115] Add 15g of toluene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 12h, so that the water generated in the reaction is carried out by the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0116] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.25 g of 4,4'-ODA and 3.25 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 4.22 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 14.1%.

[0117] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0118] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 250 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0119] 2) Preparation of block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0120] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0121] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. Then, it is placed at 150°C to evaporate the solvent, and a copper foil sample coated with a dry polyamic acid film layer is obtained, wherein the content of the strong polar solvent is 15 wt%.

[0122] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0123] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 271℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0124] Example 3

[0125] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0126] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0127] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0128] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.38 g of 4,4'-ODA and 4.97 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 6.22 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 17.1%.

[0129] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0130] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 200 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0131] 2) Preparation of block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0132] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0133] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 200 μm. Then, it is placed at 150°C to evaporate the solvent and obtain a copper foil sample coated with a dry polyamic acid film layer. The content of strong polar solvent is 15 wt%.

[0134] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0135] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 271℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0136] Example 4

[0137] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0138] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0139] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0140] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.57 g of 4,4'-ODA and 7.54 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 9.22 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 21.2%.

[0141] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0142] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0143] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0144] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0145] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0146] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0147] 3) Preparation of double-sided flexible copper clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 266℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0148] Example 5

[0149] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0150] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 1.40 g p-PDA and 0.14 g 4,4'-ODA were dispersed in 95.0 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.53 g PMDA and 2.94 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 8 h to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0151] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0152] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.60 g of 4,4'-ODA and 7.89 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 9.52 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 19.5%.

[0153] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0154] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 200 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0155] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0156] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0157] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 200 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0158] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0159] 3) Preparation of double-sided flexible copper clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 261℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0160] Example 6

[0161] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0162] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0163] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0164] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.16 g of 4,4'-ODA and 2.06 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.74 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0165] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0166] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0167] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0168] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0169] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0170] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0171] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 278℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0172] Example 7

[0173] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0174] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0175] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0176] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.15 g of 4,4'-ODA and 2.01 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.81 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0177] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0178] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0179] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0180] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0181] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0182] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0183] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 274℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0184] Example 8

[0185] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0186] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0187] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0188] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.15 g of 4,4'-ODA and 2.00 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.81 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0189] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0190] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0191] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0192] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0193] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0194] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0195] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 274℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0196] Example 9

[0197] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0198] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 4.06 g p-PDA and 0.40 g 4,4'-ODA were dispersed in 85 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure complete dissolution of the diamine compounds. After dissolution, 1.55 g PMDA and 8.99 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 15%.

[0199] 20g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0200] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.32 g of 4,4'-ODA and 4.18 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 35°C to ensure complete dissolution of the diamine compounds. 5.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 35°C, and the reaction was carried out for 16 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 22.6%.

[0201] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0202] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0203] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0204] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0205] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0206] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0207] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 280℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0208] Example 10

[0209] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0210] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 4.03 g p-PDA and 0.39 g 4,4'-ODA were dispersed in 85 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 45 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.54 g PMDA and 9.03 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 45 °C, and the reaction was carried out under a nitrogen atmosphere for 4 h to obtain a hard segment polyamic acid solution with a solid content of 15%.

[0211] 20g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0212] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.32 g of 4,4'-ODA and 4.22 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 35°C to ensure complete dissolution of the diamine compounds. 5.27 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 35°C, and the reaction was carried out for 16 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 22.6%.

[0213] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0214] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0215] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0216] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0217] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0218] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0219] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 281℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0220] Example 11

[0221] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0222] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 45 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 45 °C, and the reaction was carried out under a nitrogen atmosphere for 4 h to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0223] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0224] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 4.35g of BAPP was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25℃ to ensure complete dissolution of the diamine compounds in the solution. 6.36g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25℃, and the reaction was carried out for 16h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180℃ for 12h to obtain a block polyimide resin solution with a total solid content of 14.2%.

[0225] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0226] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0227] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0228] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0229] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0230] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0231] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 325℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0232] Example 12

[0233] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0234] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0235] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0236] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 4.31g of BAPP was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 35℃ to ensure complete dissolution of the diamine compounds in the solution. 6.42g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 35℃, and the reaction was carried out for 8 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180℃ for 12 hours to obtain a block polyimide resin solution with a total solid content of 14.2%.

[0237] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0238] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0239] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0240] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0241] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0242] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0243] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 326℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0244] Example 13

[0245] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0246] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0247] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0248] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 4.28 g of BAPP was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds. 6.45 g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 14.2%.

[0249] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0250] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0251] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0252] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0253] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0254] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0255] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 328℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0256] Example 14

[0257] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0258] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0259] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0260] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 4.27g of BAPP was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25℃ to ensure complete dissolution of the diamine compounds in the solution. 6.46g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25℃, and the reaction was carried out for 16h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180℃ for 12h to obtain a block polyimide resin solution with a total solid content of 14.2%.

[0261] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0262] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0263] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0264] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0265] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0266] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0267] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 327℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0268] Example 15

[0269] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0270] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0271] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0272] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.08 g of 4,4'-DDS and 0.24 g of 1,4-CHDA were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 35°C to ensure complete dissolution of the diamine compounds. 3.97 g of BTDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 35°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 10.6%.

[0273] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0274] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0275] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0276] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0277] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 80°C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0278] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0279] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 328℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0280] Example 16

[0281] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0282] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0283] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0284] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 3.22 g of 4,4'-DDS and 0.37 g of 1,4-CHDA were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 5.80 g of BTDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 13.2%.

[0285] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0286] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0287] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0288] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0289] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 80°C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0290] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0291] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 322℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0292] Example 17

[0293] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0294] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.64 g m-TD was dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.99 g PMDA and 0.37 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 30 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0295] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0296] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 5.12 g of 4,4'-DDS and 0.59 g of 1,4-CHDA were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 8.85 g of BTDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 17.1%.

[0297] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0298] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 225 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0299] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0300] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0301] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 225 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0302] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0303] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 321℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0304] Example 18

[0305] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0306] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 15 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 6.47 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 15 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0307] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0308] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.46 g of 4,4'-MDA and 9.81 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 5°C to ensure complete dissolution of the diamine compounds. 2.75 g of CBDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 24.1%.

[0309] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0310] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0311] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0312] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0313] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0314] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0315] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 259℃, the pressing pressure is 7MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0316] Example 19

[0317] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0318] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 4.26 g of 4,4'-DABA and 0.94 g of 4,4'-ODA were dispersed in 90 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 15 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 4.80 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 15 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 10.0%.

[0319] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 18 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0320] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.73 g of 4,4'-MDA and 11.61 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 5°C to ensure complete dissolution of the diamine compounds. 3.10 g of CBDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 18 h to obtain a block polyimide resin solution with a total solid content of 22.7%.

[0321] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0322] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0323] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0324] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0325] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0326] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0327] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 256℃, the pressing pressure is 7MPa, and the pressing time is 20s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0328] Example 20

[0329] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0330] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 3.41 g of 4,4'-DABA and 0.75 g of 4,4'-ODA were dispersed in 92 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 15 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 3.84 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 15 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 8.0%.

[0331] 10g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 18h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0332] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.10 g of 4,4'-MDA and 14.15 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 5°C to ensure complete dissolution of the diamine compounds. 3.66 g of CBDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 18 h to obtain a block polyimide resin solution with a total solid content of 23.3%.

[0333] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0334] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0335] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0336] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0337] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0338] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0339] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 249℃, the pressing pressure is 5MPa, and the pressing time is 20s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0340] Example 21

[0341] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0342] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.80 g of 4,4'-DABA and 1.28 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 15 °C to ensure complete dissolution of the diamine compounds in the solution. After dissolution, 6.42 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 15 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0343] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0344] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.43 g of 4,4'-MDA and 9.60 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 10°C to ensure complete dissolution of the diamine compounds. 2.80 g of CBDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 10°C, and the reaction was carried out for 48 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 24.0%.

[0345] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0346] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0347] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0348] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0349] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0350] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 300°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0351] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 255℃, the pressing pressure is 5MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0352] Example 22

[0353] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0354] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.71 g of 4,4'-DABA and 1.26 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 20 °C to ensure complete dissolution of the diamine compounds in the solution. After dissolution, 6.53 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 20 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0355] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0356] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.49 g of 4,4'-MDA and 10.01 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 10°C to ensure complete dissolution of the diamine compounds. 2.70 g of CBDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 10°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 24.3%.

[0357] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0358] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0359] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 330°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0360] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0361] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0362] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 330°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0363] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 260℃, the pressing pressure is 5MPa, and the pressing time is 15s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0364] Example 23

[0365] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0366] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.69 g of 4,4'-DABA and 1.25 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 20 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.56 g of PMDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 20 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0367] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0368] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.51 g of 4,4'-MDA and 10.12 g of ATPE were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 10°C to ensure complete dissolution of the diamine compounds. 2.68 g of CBDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 10°C, and the reaction was carried out for 48 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 24.3%.

[0369] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0370] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0371] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 330°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0372] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0373] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0374] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 330°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0375] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 263℃, the pressing pressure is 5MPa, and the pressing time is 15s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0376] Example 24

[0377] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0378] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 5 °C to ensure complete dissolution of the diamine compounds in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 5 °C. The reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0379] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 24h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0380] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 5.05 g of BAPP was added to the hard segment polyimide resin solution prepared in step 1) while stirring, and the solution temperature was controlled at 5°C to ensure complete dissolution of the diamine compounds in the solution. 4.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out for 48 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution, wherein the total solid content of the solution was 20.9%.

[0381] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0382] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0383] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0384] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0385] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0386] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0387] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 296℃, the pressing pressure is 10MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0388] Example 25

[0389] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0390] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 5 °C to ensure complete dissolution of the diamine compounds in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 5 °C. The reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0391] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 24h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0392] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.74 g of 4,4'-ODA and 3.54 g of BAPP were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 5°C to ensure complete dissolution of the diamine compounds. 4.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 20.4%.

[0393] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0394] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0395] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0396] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0397] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0398] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0399] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 305℃, the pressing pressure is 10MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0400] Example 26

[0401] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0402] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 5 °C to ensure complete dissolution of the diamine compounds in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 5 °C. The reaction was carried out under a nitrogen atmosphere for 48 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0403] 10g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 24h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0404] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.23 g of 4,4'-ODA and 2.53 g of BAPP were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 5°C to ensure complete dissolution of the diamine compounds in the solution. 4.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 5°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 20.0%.

[0405] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0406] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0407] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0408] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0409] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0410] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0411] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 306℃, the pressing pressure is 10MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0412] Example 27

[0413] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0414] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0415] Add 15g of xylene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 24h to remove the water generated in the reaction with the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0416] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 1.72 g of 4,4'-ODA and 1.52 g of BAPP were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds. 4.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 19.6%.

[0417] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0418] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0419] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0420] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0421] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0422] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0423] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 311℃, the pressing pressure is 10MPa, and the pressing time is 20s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0424] Example 28

[0425] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0426] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0427] Add 15g of xylene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 24h to remove the water generated in the reaction with the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0428] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.46 g of 4,4'-ODA was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds in the solution. 4.34 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 19.0%.

[0429] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0430] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 200 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0431] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0432] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0433] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 200 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0434] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0435] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 318℃, the pressing pressure is 10MPa, and the pressing time is 20s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0436] Example 29

[0437] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0438] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0439] Add 15g of xylene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 24h to remove the water generated in the reaction with the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0440] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.46 g of 4,4'-ODA was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 3.20 g of s-ODPA and 1.69 g of TAHQ were added to the solution in three portions, each representing 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 19.4%.

[0441] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0442] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0443] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0444] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0445] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0446] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0447] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 328℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0448] Example 30

[0449] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0450] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0451] 20g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 24h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0452] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.99 g of 4,4'-ODA and 3.83 g of HFBAPP were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 6.22 g of 6FDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 24 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 22.1%.

[0453] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0454] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0455] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0456] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0457] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0458] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0459] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 339℃, the pressing pressure is 10MPa, and the pressing time is 45s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0460] Example 31

[0461] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0462] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0463] 20g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0464] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 3.60 g of TPE-R was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 4.51 g of BTDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 20.0%.

[0465] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0466] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0467] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0468] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0469] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0470] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0471] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 299℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0472] Example 32

[0473] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0474] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 25 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 25 °C. The reaction was carried out under a nitrogen atmosphere for 24 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0475] 20g of xylene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0476] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.61 g of 4,4'-DAT was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 4.51 g of BTDA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 19.2%.

[0477] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0478] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0479] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0480] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0481] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0482] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0483] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 298℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0484] Example 33

[0485] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0486] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 45 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 45 °C. The reaction was carried out under a nitrogen atmosphere for 4 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0487] Add 15g of xylene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 18h to remove the water generated in the reaction with the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0488] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 3.60 g of TPE-R was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 45°C to ensure complete dissolution of the diamine compounds. 5.63 g of HQDA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 8 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 18 hours to obtain a block polyimide resin solution with a total solid content of 20.8%.

[0489] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0490] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0491] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0492] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0493] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0494] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0495] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 308℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0496] Example 34

[0497] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0498] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA and 1.27 g of 4,4'-ODA were dispersed in 86.5 g of strongly polar solvent NMP while stirring in a container. The temperature of the solution was controlled at 45 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 6.47 g of PMDA solution was added to the solution in three portions, and the temperature was maintained at 45 °C. The reaction was carried out under a nitrogen atmosphere for 4 h to obtain a hard segment polyamic acid solution with a solid content of 13.5%.

[0499] Add 15g of xylene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 18h to remove the water generated in the reaction with the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0500] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 3.60 g of TPE-R was added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 45°C to ensure complete dissolution of the diamine compounds. 7.28 g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 8 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 18 hours to obtain a block polyimide resin solution with a total solid content of 22.0%.

[0501] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0502] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0503] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0504] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0505] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0506] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0507] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 320℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0508] Example 35

[0509] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0510] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 1.56 g p-PDA and 0.15 g 4,4'-ODA were dispersed in 95.0 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.60 g PMDA and 2.69 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 8 h to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0511] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0512] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.60 g of 4,4'-ODA and 7.93 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 10.25 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 20.0%.

[0513] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0514] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0515] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0516] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0517] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0518] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0519] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 259℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0520] Example 36

[0521] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0522] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 4.02 g p-PDA and 0.39 g 4,4'-ODA were dispersed in 85 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 45 °C to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 1.53 g PMDA and 9.06 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 45 °C, and the reaction was carried out under a nitrogen atmosphere for 4 h to obtain a hard segment polyamic acid solution with a solid content of 15%.

[0523] 20g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 24 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0524] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.32 g of 4,4'-ODA and 4.24 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 35°C to ensure complete dissolution of the diamine compounds. 5.22 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 35°C, and the reaction was carried out for 16 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 24 h to obtain a block polyimide resin solution with a total solid content of 22.6%.

[0525] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0526] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0527] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0528] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0529] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0530] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0531] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 281℃, the pressing pressure is 7MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0532] Example 37

[0533] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0534] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.19 g p-PDA and 0.21 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.84 g PMDA and 4.26 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0535] Add 15g of toluene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 12h, so that the water generated in the reaction is carried out by the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0536] 2) Preparation of block polyimide resin: Under a nitrogen atmosphere, 0.14 g of 4,4'-ODA and 1.88 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds. 3.05 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 12.0%.

[0537] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0538] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 300 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0539] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0540] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0541] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 300 μm. Then, it is placed at 150°C. After the solvent evaporates, a copper foil sample coated with a dry polyamic acid film layer is obtained. The content of strong polar solvent is 15 wt%.

[0542] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0543] 3) Preparation of the double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 282℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0544] Example 38

[0545] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0546] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 1.38 g p-PDA and 0.13 g 4,4'-ODA were dispersed in 95.0 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.53 g PMDA and 2.96 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 8 h to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0547] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0548] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.60 g of 4,4'-ODA and 7.88 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 9.45 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 36 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 19.4%.

[0549] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0550] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0551] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0552] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0553] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0554] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0555] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 259℃, the pressing pressure is 5MPa, and the pressing time is 15s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0556] Example 39

[0557] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0558] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0559] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0560] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.16 g of 4,4'-ODA and 2.11 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.69 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0561] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0562] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0563] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0564] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0565] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0566] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0567] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 273℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0568] Example 40

[0569] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0570] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0571] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0572] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.16 g of 4,4'-ODA and 2.04 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.77 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0573] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0574] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0575] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0576] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0577] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0578] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0579] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 275℃, the pressing pressure is 7MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0580] Example 41

[0581] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0582] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0583] 15g of toluene was added to the above hard segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12 hours to remove the water generated in the reaction by the azeotropic dehydrating agent. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated hard segment polyimide resin.

[0584] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 0.15 g of 4,4'-ODA and 2.00 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 45°C to ensure complete dissolution of the diamine compounds. 2.81 g of s-ODPA was added to the solution in three portions, each time accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 45°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 hours to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0585] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0586] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0587] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0588] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0589] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 20 wt%.

[0590] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0591] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 275℃, the pressing pressure is 7MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0592] Example 42

[0593] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0594] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 2.08 g p-PDA and 0.20 g 4,4'-ODA were dispersed in 92.5 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.79 g PMDA and 4.42 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a hard segment polyamic acid solution with a solid content of 7.5%.

[0595] Add 15g of toluene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 12h, so that the water generated in the reaction is carried out by the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0596] 2) Preparation of block polyimide resin: Under a nitrogen atmosphere, 0.08 g of 4,4'-ODA and 1.11 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds in the solution. 1.71 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution, wherein the total solid content of the solution was 10.1%.

[0597] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0598] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 350 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 23 wt%.

[0599] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0600] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0601] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 350 μm. Then, it is placed at 150°C. After the solvent evaporates, a copper foil sample coated with a polyamic acid dry film layer is obtained. The content of strong polar solvent is 23 wt%.

[0602] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0603] 3) Preparation of the double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 284℃, the pressing pressure is 7MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0604] Example 43

[0605] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0606] 1) Preparation of hard segment polyimide resin solution: Under a nitrogen atmosphere, 1.39 g p-PDA and 0.14 g 4,4'-ODA were dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 0.53 g PMDA and 2.95 g s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a hard segment polyamic acid solution with a solid content of 5.0%.

[0607] Add 15g of toluene as an azeotropic dehydrating agent to the above hard segment polyamic acid solution, heat the solution to 180℃ and react for 12h, so that the water generated in the reaction is carried out by the azeotropic dehydrating agent, and then evaporate the azeotropic dehydrating agent from the solution at 180℃ to obtain a solution of amino-terminated hard segment polyimide resin.

[0608] 2) Preparation of block polyimide resin: Under a nitrogen atmosphere, 0.77 g of 4,4'-ODA and 10.17 g of TPE-R were added to the hard segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 12.15 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 22.8%.

[0609] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0610] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 150 μm. Then the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0611] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0612] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0613] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 150 μm. Then, it is placed at 100°C. After the solvent evaporates, a copper foil sample coated with a dry polyamic acid film layer is obtained. The content of strong polar solvent is 15 wt%.

[0614] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0615] 3) Preparation of the double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 254℃, the pressing pressure is 5MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0616] Example 44

[0617] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0618] 1) Preparation of soft segment polyimide resin solution: Under a nitrogen atmosphere, 0.18 g of 4,4'-ODA and 2.42 g of TPE-R were dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to allow the diamine compounds to completely dissolve in the solution. After dissolution, 2.39 g of s-ODPA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 12 h to obtain a soft segment polyamic acid solution with a solid content of 5.0%.

[0619] 15g of toluene was added to the above soft segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180°C and reacted for 12h. The azeotropic dehydrating agent carried away the water generated in the reaction. Then, the azeotropic dehydrating agent was evaporated from the solution at 180°C to obtain a solution of amino-terminated soft segment polyimide resin.

[0620] 2) Preparation of block polyimide resin: Under a nitrogen atmosphere, 1.97 g of p-PDA and 0.19 g of 4,4'-ODA were added to the soft segment unit polyimide resin solution prepared in step 1) while stirring. The temperature of the solution was controlled at 25°C to ensure complete dissolution of the diamine compounds in the solution. 0.75 g of PMDA and 4.97 g of s-BPDA were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 12 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Toluene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 11.9%.

[0621] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0622] 1) Coating and film formation of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a glass substrate. The wet film thickness is 300 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of the strong polar solvent is 15 wt%.

[0623] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0624] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0625] 1) Coating film of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated on a copper foil carrier. The wet film thickness is 300 μm. Then, it is placed at 150°C. After the solvent evaporates, a copper foil sample coated with a dry polyamic acid film layer is obtained. The content of strong polar solvent is 15 wt%.

[0626] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0627] 3) Preparation of the double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 276℃, the pressing pressure is 5MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0628] Example 45

[0629] 1. This embodiment provides a method for preparing block polyimide resin, including the following steps:

[0630] 1) Preparation of soft segment polyimide resin solution: Under a nitrogen atmosphere, 4.86g of BAPP was dispersed in 90g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 45℃ to ensure that the diamine compounds were completely dissolved in the solution. After dissolution, 5.14g of BPADA was added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The solution temperature was maintained at 45℃, and the reaction was carried out under a nitrogen atmosphere for 4 hours to obtain a soft segment polyamic acid solution with a solid content of 10.0%.

[0631] 10g of xylene was added to the above soft segment polyamic acid solution as an azeotropic dehydrating agent. The solution was heated to 180℃ and reacted for 12h to remove the water generated in the reaction by the azeotropic dehydrating agent. Then the azeotropic dehydrating agent was evaporated from the solution at 180℃ to obtain a solution of amino-terminated soft segment polyimide resin.

[0632] 2) Preparation of block polyamic acid solution: Under a nitrogen atmosphere, 2.14 g m-TD was added to the soft segment polyimide resin solution prepared in step 1) while stirring. The solution temperature was controlled at 25°C to ensure complete dissolution of the diamine compounds. 2.32 g PMDA and 0.30 g s-BPDA were added to the solution in three portions, each representing 60%, 30%, and 10% of the total weight of the dianhydrides, respectively. The solution temperature was controlled at 25°C, and the reaction was carried out for 16 h under a nitrogen atmosphere to obtain a block polyamic acid solution. Xylene, a dehydrating agent, was added to the obtained block polyamic acid solution, and the reaction was carried out at 180°C for 12 h to obtain a block polyimide resin solution with a total solid content of 14.1%.

[0633] 2. This embodiment provides a method for preparing a block polyimide film, comprising the following steps:

[0634] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0635] 2) Heat treatment to obtain block polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a block polyimide film with a thickness of about 25 μm.

[0636] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of a block polyimide film, including the following steps:

[0637] 1) Coating of block polyamic acid solution: The block polyamic acid solution obtained in step 2) of 1 above is coated onto a copper foil carrier, and the wet film thickness is 250 μm. It is then evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0638] 2) Preparation of single-sided flexible copper clad laminate coated with block polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with block polyimide.

[0639] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 327℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0640] Comparative Example 1

[0641] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0642] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 2.08 g p-PDA, 0.35 g 4,4'-ODA, and 2.03 g TPE-R were dispersed in 92.5 g of a strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 25 °C to ensure complete dissolution of the diamine compounds. After dissolution, 0.79 g PMDA, 4.42 g s-BPDA, and 2.79 g s-ODPA solutions were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The temperature was maintained at 25 °C, and the reaction was carried out under a nitrogen atmosphere for 24 h to obtain a thermoplastic polyamic acid solution with a solid content of 11.9%.

[0643] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0644] 1) Coating film of thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in 1 above is coated on a glass substrate. The wet film thickness is 300 μm. Then the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a polyamic acid dry film layer. The content of strong polar solvent is 15 wt%.

[0645] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0646] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0647] 1) Coating film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0648] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0649] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 296℃, the pressing pressure is 10MPa, and the pressing time is 10s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0650] Comparative Example 2

[0651] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0652] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 2.64 g m-TD and 4.35 g BAPP were dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 45 °C to ensure complete dissolution of the diamine compounds. After dissolution, 1.99 g PMDA, 0.37 g s-BPDA, and 6.36 g BPADA solutions were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The temperature was maintained at 45 °C, and the reaction was carried out for 8 h under a nitrogen atmosphere to obtain a thermoplastic polyamic acid solution with a solid content of 14.2%.

[0653] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0654] 1) Coating and film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in step 1 above is coated onto a glass substrate, and the wet film thickness is 250 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0655] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0656] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0657] 1) Coating film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps is coated onto a copper foil carrier, and the wet film thickness is 250 μm. Then, it is evaporated at 80 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0658] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 380°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0659] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 345℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0660] Comparative Example 3

[0661] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0662] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 2.64 g m-TD, 2.08 g 4,4'-DDS and 0.24 g 1,4-CHDA were dispersed in 95 g of strongly polar solvent NMP in a container while stirring. The temperature of the solution was controlled at 30 °C to ensure complete dissolution of the diamine compounds. After dissolution, 1.99 g PMDA, 0.37 g s-BPDA and 3.97 g BTDA solutions were added to the solution in three portions, with each addition accounting for 60%, 30% and 10% of the total weight of the dianhydrides, respectively. The temperature was maintained at 30 °C, and the reaction was carried out under a nitrogen atmosphere for 24 h to obtain a thermoplastic polyamic acid solution with a solid content of 10.6%.

[0663] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0664] 1) Coating and film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in step 1 above is coated onto a glass substrate, and the wet film thickness is 300 μm. Then, the coated glass substrate is placed at 80°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0665] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0666] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0667] 1) Coating film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps is coated onto a copper foil carrier, and the wet film thickness is 300 μm. Then, it is evaporated at 80°C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 25 wt%.

[0668] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0669] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 324℃, the pressing pressure is 10MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0670] Comparative Example 4

[0671] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0672] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA, 1.27 g of 4,4'-ODA, 1.46 g of 4,4'-MDA, and 9.81 g of ATPE were dispersed in 86.5 g of a strongly polar solvent, NMP, in a container with stirring. The temperature of the solution was controlled at 15 °C to ensure complete dissolution of the diamine compounds. After dissolution, 6.47 g of PMDA and 2.75 g of CBDA solution were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The temperature was maintained at 15 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a thermoplastic polyamic acid solution with a solid content of 24.1%.

[0673] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0674] 1) Coating and film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in step 1 above is coated onto a glass substrate, and the wet film thickness is 150 μm. Then, the coated glass substrate is placed at 100°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0675] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0676] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0677] 1) Coating film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps is coated onto a copper foil carrier, and the wet film thickness is 150 μm. Then, it is evaporated at 100°C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 23 wt%.

[0678] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0679] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is bonded to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 309℃, the pressing pressure is 7MPa, and the pressing time is 60s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0680] Comparative Example 5

[0681] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0682] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA, 1.27 g of 4,4'-ODA, and 5.05 g of BAPP were dispersed in 86.5 g of a strongly polar solvent, NMP, in a container with stirring. The temperature of the solution was controlled at 5 °C to ensure complete dissolution of the diamine compounds. After dissolution, 6.47 g of PMDA and 4.34 g of s-ODPA solution were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The temperature was maintained at 5 °C, and the reaction was carried out under a nitrogen atmosphere for 48 h to obtain a thermoplastic polyamic acid solution with a solid content of 20.9%.

[0683] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0684] 1) Coating and film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in step 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 120°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 18 wt%.

[0685] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0686] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0687] 1) Coating with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps was coated onto a copper foil carrier, and the wet film thickness was 175 μm. Then, it was evaporated at 120 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent was 18 wt%.

[0688] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 350°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0689] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 318℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0690] Comparative Example 6

[0691] 1. This comparative example provides a method for preparing a thermoplastic polyamic acid solution, comprising the following steps:

[0692] Preparation of thermoplastic polyamic acid solution: Under a nitrogen atmosphere, 5.76 g of 4,4'-DABA, 1.27 g of 4,4'-ODA, and 3.60 g of TPE-R were dispersed in 86.5 g of a strongly polar solvent, NMP, in a container with stirring. The temperature of the solution was controlled at 45 °C to ensure complete dissolution of the diamine compounds. After dissolution, 6.47 g of PMDA and 7.28 g of BPADA solution were added to the solution in three portions, with each addition accounting for 60%, 30%, and 10% of the total weight of the dianhydride compounds, respectively. The temperature was maintained at 45 °C, and the reaction was carried out for 8 hours under a nitrogen atmosphere to obtain a thermoplastic polyamic acid solution with a solid content of 22.0%.

[0693] 2. This embodiment provides a method for preparing a thermoplastic polyimide film, including the following steps:

[0694] 1) Coating and film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution obtained in step 1 above is coated onto a glass substrate, and the wet film thickness is 175 μm. Then, the coated glass substrate is placed at 150°C to evaporate the solvent and obtain a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0695] 2) Preparation of thermoplastic polyimide film: In a nitrogen atmosphere, the carrier coated with polyamic acid dry film layer obtained in step 1) is placed in an oven at 400°C for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer. After boiling in water, the polyimide film is peeled off from the surface of the carrier to obtain a thermoplastic polyimide film with a thickness of about 25 μm.

[0696] 3. This embodiment provides a method for preparing a double-sided flexible copper-clad laminate of thermoplastic polyimide film, including the following steps:

[0697] 1) Coating film formation with thermoplastic polyamic acid solution: The thermoplastic polyamic acid solution prepared in the above steps is coated onto a copper foil carrier, and the wet film thickness is 175 μm. Then, it is evaporated at 150 °C to obtain a copper foil sample coated with a dry polyamic acid film layer, wherein the content of the strong polar solvent is 15 wt%.

[0698] 2) Preparation of single-sided flexible copper clad laminate coated with thermoplastic polyimide: In a nitrogen atmosphere, the copper foil sample coated with polyamic acid dry film layer in step 1) is placed in an oven at 400℃ for heat treatment. The polyamic acid undergoes an imidization reaction to obtain a polyimide film layer, thus forming a single-sided flexible copper clad laminate coated with thermoplastic polyimide.

[0699] 3) Preparation of double-sided flexible copper-clad laminate: A copper foil is attached to the polyimide side of the single-sided flexible copper-clad laminate obtained in step 2), and then placed in a high-temperature flatbed press for hot pressing. The pressing temperature is 330℃, the pressing pressure is 10MPa, and the pressing time is 30s. After hot pressing, a double-sided flexible copper-clad laminate sample is obtained, wherein the polyimide layer thickness is approximately 25μm.

[0700] Test case

[0701] 1) Glass transition temperature (Tg) test. The glass transition temperature of TPI films was tested using a TA Q800 instrument. The TPI film sample was fixed on the testing instrument using a film stretching fixture. The initial temperature was set to 30℃, and the temperature was increased to 400℃ at a rate of 10℃ / min, followed by direct natural cooling without pause. During the heating process, the testing instrument continuously collected sample data, and the glass transition temperature of the TPI film was finally determined based on the peak value of tanσ.

[0702] 2) Linear Coefficient of Thermal Expansion (CTE) Test. The linear coefficient of thermal expansion of TPI films was tested using TA's Q400. The TPI film samples were preheated in a 150℃ oven for 30 min, then cooled to room temperature in a desiccator. Within 30 min of cooling, the preheated samples were fixed to the testing instrument using a film stretching fixture. The initial temperature was set to 30℃, and the temperature was increased to 250℃ at a rate of 5℃ / min, followed by natural cooling. During the heating process, the testing instrument continuously collected sample data. Finally, the linear coefficient of thermal expansion of the TPI film was determined based on the average slope of the curve within the stable range of 100-200℃.

[0703] 3) Thermal decomposition temperature (Td) 5％The thermal decomposition temperature of the polyimide film was tested using TA's Q50 instrument. The initial temperature was set to 30°C, and the temperature was increased to 800°C at a rate of 10°C / min, followed by natural cooling. During the heating process, the instrument continuously collected sample data, and the temperature at which 5% weight loss was achieved was taken as the thermal decomposition temperature of the TPI film.

[0704] 4) Tensile strength and elongation at break test. The tensile strength and elongation at break of the TPI film were tested using a universal tensile testing machine. The TPI film was mounted on a fixture equipped with extensometers, with a clamping distance of 5 cm and a force range of 100 N for the tensile fixture. The universal tensile testing machine was then started, and a tensile test was performed at a rate of 50.8 mm / min. The force and displacement data were recorded in real time during the tensile process until the TPI film broke. Finally, the tensile strength and elongation at break were calculated.

[0705] 5) Dimensional Stability Test. The dimensional stability of the FCCL samples was tested using a 2D image analyzer. A 25cm x 30cm flexible copper-clad laminate sample was cut, and marks were made on the inner sides of its four corners. The sample was then placed in an environment at 25℃ and 55% relative humidity for 24 hours. The lengths of the four sides of the rectangle marked at the four corners were measured and recorded as L0. The copper foil was then etched away using an etching solution, and the sample was again placed in an environment at 25℃ and 55% relative humidity for 24 hours. The lengths of the four sides of the rectangle marked at the four corners were measured and recorded as L1. The dimensional stability of the FCCL sample was calculated using the formula "Dimensional Stability = (L1 - L0) / L0".

[0706] 6) Peel Strength Test. A universal tensile testing machine was used to test the peel strength of the FCCL samples. The copper foil layer on the flexible copper-clad laminate sample was etched into a rectangular shape with a width of 3 mm and a length greater than 20 cm. One end of the copper strip was peeled approximately 5 cm from the polyimide insulation layer. After peeling, the flexible copper-clad laminate sample was fixed to the fixture using a flat clamp, and the peeled copper strip was simultaneously fixed to a movable clamp. The force range of the tensile clamp was 20 N. The universal tensile testing machine was started, and tensioning was performed at a rate of 50.8 mm / min. During tensioning, the copper strip of the glass was kept at a 90° angle to the plane of the flexible copper-clad laminate sample. The peel force value was recorded in real time during the tensioning process. Finally, the flat and stable segment on the curve was selected, and the peel strength of the FCCL sample was calculated using the formula "peel strength = peel force value / copper strip width".

[0707] Among them, in the above-mentioned dimensional stability test and peel strength test, the etching method of FCCL includes the following steps: first, prepare an acidic CuCl2 etching solution with pH=1, then immerse the flexible copper-clad laminate sample in the above-prepared etching solution, and stop immersion when the copper foil surface is etched away.

[0708] To compare the effects of the degree of polymerization or molar ratio of soft segment units on the glass transition temperature (Tg), linear coefficient of thermal expansion (CTE), thermal decomposition temperature (Td5%), tensile strength and elongation at break, dimensional stability, and peel strength of block-type TPI films and flexible copper clad laminate (FCCL) films, the formulations, sample parameters, and performance test results of Examples 1-5, Example 11, and Examples 15-20 are shown in Table 2 below:

[0709] Table 2

[0710] As shown in Table 2, in Examples 1-5, by selecting the same hard segment unit formulation and degree of polymerization, and keeping the total degree of polymerization of the final block-type TPI constant, changing the degree of polymerization / molar ratio of the soft segment units resulted in significant changes in the performance of the TPI film. Example 1 had a suitable degree of polymerization and molar ratio of the soft segment units. In Examples 2-5, the degree of polymerization / molar ratio of the soft segment units continuously increased from 30% to 70%, resulting in a decrease in Tg and Td. 5％ As the proportion of hard segments decreases, the tensile strength decreases, the CTE increases, and the greater the deviation of dimensional stability from 0%, the worse the above properties tend to be. Soft segment units contain more flexible groups such as ether groups, ester groups, methylene groups, and isopropylidene groups. When the proportion of soft segment units increases, the proportion of hard segment units decreases accordingly. The combined effect of these two factors worsens the thermal stability and tensile strength of the TPI film. Simultaneously, a decrease in the proportion of hard segment units also leads to a decrease in the CTE and dimensional stability of the TPI film. Increasing the degree of polymerization / molar ratio of soft segment units has the beneficial effect of increasing the elongation at break and peel strength of the TPI film.

[0711] The comparative results of Examples 15-17 also illustrate the same trend described above. However, compared to Examples 1-5, the dianhydride and diamine raw materials used in the soft segment units in Examples 15-17 are different, resulting in different optimal values ​​for the proportion of soft segment units. Experiments show that the optimal proportion of soft segment units in Examples 1-5 is 30%, while the optimal proportion of soft segment units in Examples 15-17 is 50%. In Examples 18-20, due to the excessive flexibility of the soft segment unit molecular chain, the Tg is the lowest, the CTE is the highest, and other properties are slightly worse than those of the other example groups.

[0712] To compare the effects of the total degree of polymerization of block TPI on the glass transition temperature (Tg), linear coefficient of thermal expansion (CTE), thermal decomposition temperature (Td5%), tensile strength and elongation at break, dimensional stability, and peel strength of thermoplastic polyimide (TPI) films and flexible copper clad laminates (FCCL), the formulations, sample parameters, and performance test results of Examples 1, 6-8, and 11-14 are shown in Table 3 below:

[0713] Table 3

[0714] As shown in Table 3, in Examples 1 and 6-8, keeping other parameters constant, the degree of polymerization increased from 50 to 300, and Td... 5％ Tensile strength, elongation at break, dimensional stability, and peel strength increase, while Tg and CTE remain essentially unchanged. An increase in the total degree of polymerization leads to an increase in the molecular weight of TPI, and improvements in various microscopic parameters such as molecular chain length, chain entanglement, and chain regularity, thus enhancing performance. This indicates that controlling the total degree of polymerization of the final block TPI is necessary.

[0715] The same trend can also be seen in Examples 11-14. As the total degree of polymerization increases, the results of Tg and CTE remain basically unchanged, while other properties are improved to varying degrees.

[0716] To compare the effects of the degree of polymerization of the hard segment units of block TPI on the glass transition temperature (Tg), linear coefficient of thermal expansion (CTE), thermal decomposition temperature (Td5%), tensile strength and elongation at break, dimensional stability, and peel strength of thermoplastic polyimide (TPI) films and flexible copper clad laminate (FCCL) films, the formulations, sample parameters, and performance test results of Examples 1, 9-10, 18, and 21-23 are shown in Table 4 below:

[0717] Table 4

[0718] Table 4 shows that in Examples 1 and 9-10, keeping other parameters constant, increasing the degree of polymerization of the hard segment units reveals that the elongation at break decreases with increasing hard segment unit polymerization, indicating a deterioration in film toughness. Increased polymerization of the hard segment units affects the "anchoring" effect between the molecular chains and the copper foil surface, leading to decreased peel strength. Simultaneously, it improves the regularity of molecular chain assembly, causing a more oriented arrangement and thus reducing CTE. Therefore, the degree of polymerization of the hard segment units needs to be controlled within a suitable range; it should be as low as possible while maintaining good tensile strength and optimal molecular chain assembly regularity.

[0719] In Examples 18 and 21-23, the degree of polymerization of the hard segment units was changed. Compared to Examples 1 and 9-10, the soft segment unit molecular chains were more flexible. Therefore, the increased degree of polymerization of the hard segment units significantly improved the dimensional stability of the product, reduced the adverse effects of the soft segment units on performance, and showed better synergy with the soft segment units. This indicates that the formulation, degree of polymerization, and ratio of the hard segment units need to be rationally combined with those of the soft segment units to complement each other and achieve an overall improvement in performance.

[0720] To compare the effects of the combination ratio of soft segment diamines in block-type TPI on the glass transition temperature (Tg), linear coefficient of thermal expansion (CTE), thermal decomposition temperature (Td5%), tensile strength and elongation at break, dimensional stability, and peel strength of thermoplastic polyimide (TPI) films and flexible copper clad laminate (FCCL) films, the formulations, sample parameters, and performance test results of Examples 24-34 are shown in Table 5 below:

[0721] Table 5

[0722] As shown in Table 5, in Examples 24-28, the hard segment unit formulation, degree of polymerization, and total degree of polymerization remained consistent. The dianhydrides and diamines used in the soft segment units were of the same type, but the ratios of the diamines differed. The variation in the type of diamine used in the soft segment units caused changes in the Tg, thermal decomposition temperature, tensile strength, and CTE of the final block-type TPI within a certain range, indicating that adjusting the diamine ratio in the soft segment units affects the performance of the final block-type TPI.

[0723] In Examples 29-34, different types of dianhydrides and diamines were used for the soft segment units, but the degree of polymerization, ratio, and total degree of polymerization of the hard segment units and soft segment units remained consistent. Although the performance of the block TPI varied, it remained within a relatively optimal range.

[0724] Although the types of dianhydrides and diamines used in the soft segment units affect the performance of block TPIs, the performance parameters still fall within a relatively optimal range, indicating that this effect is not decisive. The decisive factors for the final performance of block TPIs are the degree of polymerization and ratio of hard segment units and soft segment units, as well as the total degree of polymerization of the TPI.

[0725] To compare the performance differences between block-type TPIs and conventional TPIs, the performance test results of Examples 1, 11, 15, 18, 24, 34, and Comparative Examples 1-6 are shown in Table 6 below:

[0726] Table 6

[0727] Table 6 shows that Comparative Examples 1-6 did not use the block TPI preparation process, but instead used a conventional two-step process to prepare TPI and FCCL. Comparative Examples 1-6 used the same types and quantities of dianhydrides and diamines as Examples 1, 11, 15, 18, 24, and 34, respectively, to compare the beneficial effects of the block TPI process using the same formulation. In the test results of Comparative Examples 1-6, the tensile strength was only around 100 MPa, with a maximum of 131 MPa; the CTE was significantly high, generally exceeding 50 ppm / K; dimensional stability was poor, and shrinkage was significant. The TPI prepared by the two-step process in Comparative Examples 1-6 had poor performance, and the obtained TPI could not be used alone in TPI films and FCCL products. Therefore, under the same conditions of using dianhydride and diamine raw materials, the block TPI of this application can effectively control tensile strength, CTE, dimensional stability, and other properties to improve the performance of TPI, and can also meet the application requirements of TPI films and FCCL products.

[0728] To compare the effects of hard segment unit polymerization degree x, hard segment unit polymerization degree y, and total polymerization degree n on the block polyimide resin of this application, the key parameters and performance test results of Examples 1, 5, 10, and 35-41 are shown in Table 7 below:

[0729] Table 7

[0730] As shown in Table 7, in Example 35, the degree of polymerization of the hard segment unit was 3.5, which is less than 5. Compared to Example 5, the lower degree of polymerization of the hard segment unit resulted in poor regularity of molecular chain assembly and a lack of directional alignment of the molecular chains. This led to a higher CTE and poor dimensional stability, making it unsuitable for use in flexible copper-clad laminate products. The mechanical strength of the resulting polyimide resin was also lower.

[0731] In Example 36, the degree of polymerization of the hard segment unit is 30, which is greater than 25. Compared to Example 10, the higher degree of polymerization of the hard segment unit, while achieving better heat resistance and tensile strength, leads to a deterioration in the performance of the polyimide resin, failing to meet the requirements. The polyimide resin exhibits poor toughness, with an elongation at break of only 17%; poor dimensional stability; and low peel strength, making it unsuitable for continued use in flexible copper-clad laminate products.

[0732] In Example 37, the degree of polymerization of the soft segment unit is 2.6, which is less than 5. Compared with Example 1, the lower degree of polymerization of the soft segment unit reduces the flexibility of the molecular chain. Although better heat resistance and tensile strength can be obtained, the elongation at break and peel strength decrease rapidly, which will lead to a deterioration in the performance of the polyimide resin and does not meet the requirements for use in flexible copper clad laminate products.

[0733] In Example 38, the degree of polymerization of the soft segment unit is 31, which is greater than 25. Compared with Example 5, the higher degree of polymerization of the soft segment unit results in excessively flexible molecular chains, a higher CTE of the polyimide resin, and a dimensional stability of -0.19%, which does not meet the requirements for use in flexible copper-clad laminate products.

[0734] In Examples 39-41, other parameters remained unchanged, with the total degree of polymerization of the molecular chain being 30, 70, and 250, respectively. In Example 39, the total degree of polymerization of the molecular chain was 30, indicating a low molecular weight of the polyimide resin, resulting in poor mechanical properties such as tensile strength and elongation at break, low peel strength, and unacceptable performance. A total degree of polymerization of 70 met the performance requirements. However, when the total degree of polymerization of the molecular chain reached over 200, as in Examples 41, 8, and 14, the molecular weight was too high. Although various performance indicators were significantly improved, the processing performance was poor. Polyimide resin has very poor solubility in solution and cannot be processed into polyimide solution by direct heating in solution. It can only be processed by coating the polyimide solution and high-temperature imidization.

[0735] To compare the effects of the proportion of soft segment units and the order in which soft and hard segment units are prepared on the block polyimide resin of this application, the key parameters and performance test results of Examples 1, 11, and 42-45 are shown in Table 8 below:

[0736] Table 8

[0737] As shown in Table 8, in Example 42, the number of polymeric units in the soft segment unit accounts for 20% of the total number of polymeric units on the molecular backbone. Compared to Example 1, the lower proportion of soft segment units results in a stronger rigidity of the molecular backbone, a significant decrease in CTE, and unacceptable peel strength. In Example 43, the number of polymeric units in the soft segment unit accounts for 75% of the total number of polymeric units on the molecular backbone. Compared to Example 1, the higher proportion of soft segment units results in a stronger flexibility of the molecular backbone, a significantly worse dimensional stability (-0.23%), which is unacceptable.

[0738] In Examples 44 and 45, soft segment units of polyimide resin were first polymerized, followed by the addition of raw material monomers for hard segment units to the solution of the soft segment units for further polymerization. Comparative experiments with Examples 1 and 11 showed no significant differences between Examples 44 and 45; this indicates that whether the hard segment units are polymerized first or the soft segment units are polymerized first, the resulting block polyimide resin does not exhibit any difference in performance.

[0739] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A block polyimide resin, wherein, The molecular backbone of the block polyimide resin includes alternating hard segment units and soft segment units. The hard segment units have the structure shown in Formula I, and the soft segment units have the structure shown in Formula II. In Equation I, 5 ≤ x ≤ 25, and Ar1 is selected from... and / or Ar2 is selected from One or more of the following, wherein R1 is selected from H, C1-C3 alkyl or trifluoromethyl, and L1 is selected from single bond, ether bond or -C(O)NH-; In Equation II, 5 ≤ y ≤ 25, and B is selected from... One or more of the following, wherein R2 is selected from H, C1-C3 alkyl or trifluoromethyl, R3 and R4 are each independently selected from H or methyl, and L2 is selected from ether bond, -C(R5R6)-, -C(O)-, One or more of them, wherein R5 and R6 are each independently selected from H, C1-C3 alkyl or trifluoromethyl; A is selected from One or more of 1,6-hexene; z is 32-34, and L3, L4, and L5 are each independently selected from ether bonds, methylene groups, -C(O)-, -S(O2)-, R7 and R8 are each independently selected from H, methyl, or trifluoromethyl.

2. The block polyimide resin according to claim 1, wherein, The degree of polymerization of the molecular backbone is ≥50.

3. The block polyimide resin according to claim 2, wherein, The degree of polymerization of the molecular backbone is 100 to 200.

4. The block polyimide resin according to claim 1, wherein, The number of polymeric units in the soft segment unit accounts for 30% to 70% of the total number of polymeric units in the molecular backbone.

5. The block polyimide resin according to any one of claims 1-4, wherein, The glass transition temperature of the block polyimide resin is 200–300°C; and / or, the thermal decomposition temperature of the block polyimide resin is ≥450°C.

6. A method for preparing the block polyimide resin according to any one of claims 1-5, wherein, Includes the following steps: 1) Preparation of polyimide resin solutions with hard segment units or soft segment units Under an inert atmosphere, diamine compound N1 is dissolved in a solvent, and dianhydride compound G1 is added to it. The reaction is carried out at 5–45°C for 4–48 h to obtain a hard-segment or soft-segment polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain an amino-terminated hard-segment or soft-segment polyimide resin solution. 2) Preparation of block polyimide resin Under an inert atmosphere, a diamine compound N2 is added to the amino-terminated hard-segment or soft-segment polyimide resin solution prepared in step 1) and dissolved. Then, a dianhydride compound G2 is added, and the reaction is carried out at 5–45°C for 4–48 h to obtain a block polyamic acid solution. An azeotropic dehydrating agent is added to the polyamic acid solution, and the reaction is carried out at 150–180°C for 12–24 h to remove the water generated in the reaction. Then, the azeotropic dehydrating agent is removed from the solution at 180°C to obtain the block polyimide resin solution. Alternatively, the block polyamic acid solution is heat-treated at 300–400°C to obtain the block polyimide resin. The diamine compound N1 and the diamine compound N2 are different and have structures of Formula 1 and Formula 2, respectively: H2N-Ar2-NH2 (Formula 1); H2N-A-NH2 (Formula 2); The dianhydride compounds G1 and G2 are different and have structures of Formula 3 and Formula 4, respectively: When the diamine compound N1 has the structure shown in Formula 1, the dianhydride compound G1 has the structure shown in Formula 3; when the diamine compound N2 has the structure shown in Formula 2, the dianhydride compound G2 has the structure shown in Formula 4.

7. The preparation method according to claim 6, wherein, The dianhydride compound G1 and / or the dianhydride compound G2 were added to the reaction system in three separate portions at amounts of 60 wt%, 30 wt%, and 10 wt%, respectively.

8. The preparation method according to claim 6 or 7, wherein, In step 1), the solid content of the polyamic acid solution of the hard segment unit or soft segment unit is 5% to 15%. And / or, in step 2), the solid content of the block polyamic acid solution is 10% to 25%.

9. A block polyimide film, wherein, Includes the block polyimide resin according to any one of claims 1-5.

10. The block polyimide film according to claim 9, wherein, The film has a tensile strength ≥150MPa, an elongation at break ≥20%, a linear coefficient of thermal expansion of 15~40ppm / K, and an absolute value of dimensional stability ≤0.15%.

11. A flexible copper-clad laminate, wherein, Includes the block polyimide film as described in claim 9 or 10 and copper foil laminated to one or both surfaces of the block polyimide film.

12. The application of the flexible copper-clad laminate of claim 11 in the field of circuit boards.

Images