A bismaleimide composition, prepreg and method of making and use thereof

Abstract

The application belongs to the technical field of composite materials, and provides a bismaleimide composition, a prepreg, and a preparation method and application thereof. The preparation of the bismaleimide composition comprises the following steps: (1) uniformly mixing bismaleimide monomers and allyl-containing active comonomers to obtain a homogeneous resin mixture; (2) pre-polymerizing the homogeneous resin mixture, and controlling the viscosity of the resin system after pre-polymerization to obtain a pre-polymerized resin; (3) mixing the pre-polymerized resin with a reactive modifier containing active unsaturated end groups; and (4) adding a toughening agent and a polymerization inhibitor, and stirring at low temperature to obtain a bismaleimide resin composition. The bismaleimide prepreg is prepared from the bismaleimide resin composition. The technical problem that the bismaleimide composition resin system in the prior art has poor room-temperature lay-up property, insufficient viscosity, a short cold storage period, and cannot simultaneously meet the requirement of ultrahigh heat resistance is solved.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a bismaleimide composition, a prepreg, its preparation method, and its application. Background Technology

[0002] Bismaleimide (BMI) resin is a high-performance thermosetting resin with maleimide groups as active end groups. Its unique molecular structure endows it with numerous superior properties, including exceptional high-temperature thermal stability, excellent low-loss dielectric properties, high specific strength and specific modulus, and outstanding comprehensive mechanical and physicochemical properties. Due to its core performance advantages, BMI resin has become a core matrix resin for preparing high-temperature resistant, lightweight, high-strength, and high-performance composite structural components in cutting-edge fields such as aerospace, high-precision equipment, rail transportation, and electronics, making its application scenarios irreplaceable. After high-temperature curing and cross-linking, the glass transition temperature (Tg) of the BMI resin curing system can generally reach the range of 250–320℃, enabling it to withstand long-term high-temperature, high-pressure, and complex stress ultra-high-temperature harsh service environments, fully meeting the heat resistance requirements of high-end equipment under extreme operating conditions.

[0003] However, due to limitations in its molecular structure and physicochemical properties, BMI resin exhibits significant molding process defects in the industrial preparation and practical application of prepregs, greatly hindering its large-scale promotion and application. Commonly used BMI monomers, particularly the widely used 4,4'-bismaleimide diphenylmethane monomer, generally have melting temperatures exceeding 150℃. At room temperature, they exist as a hard solid or high-viscosity semi-solid state, exhibiting a narrow melt flow window and extremely poor rheological properties at room temperature. This characteristic directly results in carbon fiber and glass fiber prepregs prepared using pure BMI resin as the matrix exhibiting problems such as insufficient room temperature viscosity, poor fabric layup flexibility, and low adhesion. These defects make them unsuitable for the core requirements of mainstream molding processes commonly used in aerospace composite parts, such as manual layup, automated fiber layup, and automated tape layup, regarding the viscoelastic properties and adhesion performance of prepregs, significantly increasing the difficulty of molding and processing.

[0004] In existing industrial modification technologies, the industry commonly uses the introduction of allyl compounds (most commonly diallyl bisphenol A) as reactive diluents and copolymerizing monomers. This copolymerization process optimizes the melt flow properties of the BMI resin system, effectively reducing melt viscosity, widening the processing window, and improving molding processability. However, the simple BMI / allyl compound binary modification system has significant performance limitations. While effectively improving room temperature spreadability and viscosity, it significantly sacrifices the resin system's heat resistance, causing a substantial decrease in the cured product's heat resistance (Tg), making it impossible to maintain the resin's original ultra-high heat resistance.

[0005] To further optimize the processability and curing toughness of BMI resin systems, some existing research and technical solutions involve adding thermoplastic resins such as polyethersulfone and polyimide, or various non-reactive plasticizers, to the system. The toughening effect of the thermoplastic components and the lubricating effect of the plasticizers are used to improve the flexibility and molding processability of the cured resin. However, this type of modification has significant drawbacks. It not only further worsens the room temperature tack of the prepreg, increasing the difficulty of laying and molding, but also, most of these modifying components do not participate in the construction of the resin curing crosslinking network, acting as inert fillers. The introduction of such components directly reduces the crosslinking density of the BMI resin curing system, destroying the dense crosslinking network structure, ultimately causing a significant decrease in the Tg of the cured product, making it difficult to meet the stringent heat resistance requirements (≥320℃) of high-end composite materials.

[0006] In summary, how to overcome the performance balance problem in the same BMI prepreg resin system through precise formulation design and modification technology, and simultaneously achieve high room temperature lay-upability, excellent adhesion, ultra-long storage stability under refrigerated storage conditions, and ultra-high Tg after curing, is a key technical challenge that has not yet been effectively solved and urgently needs to be overcome in the field of BMI resin modification and prepreg preparation. Summary of the Invention

[0007] The purpose of this invention is to provide a bismaleimide composition, prepreg, preparation method and application thereof, in order to solve the technical problems of poor room temperature spreadability, insufficient viscosity, short cold storage period and significant decrease in Tg of cured product after the introduction of modified components to improve processability in the existing bismaleimide composition resin system, which cannot simultaneously meet the requirements of ultra-high heat resistance.

[0008] To achieve the above objectives, the solution adopted by the present invention is as follows: A bismaleimide composition, wherein the raw materials comprise, by weight parts: 60-100 parts of bismaleimide monomer, 20-60 parts of allyl-containing reactive comonomer, 10-40 parts of reactive modifier containing reactive unsaturated end groups, 0.5-2.5 parts of polymerization inhibitor and 15-25 parts of toughening agent.

[0009] Furthermore, in a preferred embodiment of the present invention, the reactive modifier containing an active unsaturated end group includes at least one of heterocyclic polyenes and aromatic polyenes.

[0010] Furthermore, in a preferred embodiment of the present invention, the reactive modifier containing an active unsaturated end group includes at least one of TAIC (traceryl isocyanurate), THEICTA (tris(2-hydroxyethyl) isocyanurate triacrylate), TALC (traceryl cyanurate), IBOA (isobornyl acrylate), IBOMA (isobornyl methacrylate), and EADMA (2-ethyl-2-adamantane methacrylate).

[0011] Further, in a preferred embodiment of the present invention, the polymerization inhibitor includes at least one of: TEMPO (2,2,6,6-tetramethylpiperidine-1-oxo radical), 4-hydroxy TEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical), 4-butoxy TEMPO (4-butoxy-2,2,6,6-tetramethylpiperidine-1-oxo radical), and TEMPO ketone (2,2,6,6-tetramethyl-4-piperidinone-1-oxo radical).

[0012] Furthermore, in a preferred embodiment of the present invention, the bismaleimide monomer includes at least one of aromatic diamine type and polyamine type maleimide.

[0013] Furthermore, in a preferred embodiment of the present invention, the allyl-containing active comonomer includes at least one of diallyl bisphenol A, diallyl bisphenol S, and diallyl aniline.

[0014] Furthermore, in a preferred embodiment of the present invention, the toughening agent includes at least one of nitrile rubber, thermoplastic powder, and core-shell rubber.

[0015] A method for preparing the above-mentioned bismaleimide composition includes: (1) The bismaleimide monomer and the allyl-containing reactive comonomer were heated and mixed evenly at 100°C to obtain a homogeneous resin mixture; (2) The homogeneous resin mixture was prepolymerized at 140℃ for 0.5-4h, and the viscosity of the resin system after prepolymerization was controlled at 70℃ to be 6000-20000mPa·s to obtain prepolymerized resin. (3) Add the prepolymer resin and the reactive modifier containing active unsaturated end groups into the stirred tank and mix evenly; (4) Add toughening agent and polymerization inhibitor, stir evenly at below 60°C to obtain bismaleimide resin composition.

[0016] A bismaleimide prepreg is prepared by: hot-melt coating the above-mentioned bismaleimide resin composition at 60-80°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing fiber layer and lower resin film in the order of upper and lower, impregnating them with heated rollers at 90-100°C, and cooling to obtain a bismaleimide prepreg with a resin content of 35-42%.

[0017] Application of the above-mentioned bismaleimide prepreg in the preparation of high-performance high-temperature resistant composite structural parts.

[0018] The beneficial effects of the bismaleimide composition, prepreg, preparation method, and application provided by this invention are: (1) The bismaleimide composition provided by the present invention, by introducing a reactive modifier containing an active unsaturated end group into the bismaleimide composition resin system, replaces the non-reactive plasticizer that does not participate in curing and crosslinking in the prior art, can fundamentally solve the core technical contradiction between processability improvement and ultra-high heat resistance. The reactive modifier containing active unsaturated end groups imparts suitable flexibility and viscosity to the resin system at room temperature, meeting the viscoelastic performance requirements of prepregs in manual and automated lay-up molding processes, thereby improving the lay-up properties of the prepregs. During high-temperature curing, its active unsaturated end groups undergo addition copolymerization with bismaleimide monomers, participating in the construction of a dense cross-linked network. This processability is achieved without sacrificing cross-linking density, ensuring that the cured product's Tg is not lower than 320°C. This has significant advantages over the existing technology that introduces non-reactive plasticizers, causing the Tg to drop below 320°C. This application can maintain an ultra-high Tg of the cured product while achieving high lay-up properties and high viscosity. Meanwhile, the polymer inhibitor molecules have stable nitrogen and oxygen free radicals that can rapidly capture carbon free radicals at room temperature. The two quickly combine to form inert C-ON covalent bonds, the free radicals are locked, and chain growth is directly terminated, thus completely preventing the free radical polymerization of acrylic acid and allyl at room temperature. At the same time, it undergoes homolytic decomposition at high temperature and releases free radicals again. It not only no longer inhibits polymerization, but can also help to initiate double bond crosslinking. (2) The bismaleimide composition provided by the present invention, through the synergistic combination of reactive modifiers containing active unsaturated end groups and active comonomers containing allyl groups, and the effective inhibition of room temperature prepolymerization rate by polymerization inhibitors, enables the prepreg to be stored for more than 6 months under refrigeration conditions. This is significantly longer than the storage period of prepregs using only the binary system of bismaleimide / allyl compounds in the prior art (which is usually only a few weeks to a few months), reducing the risk of performance degradation of prepregs during storage and use, and improving the flexibility of production and use. (3) The preparation method of the bismaleimide composition provided by the present invention can precisely control the viscoelastic state of the resin system in the prepreg preparation stage within a specific window (viscosity of 3000~10000 mPa·s at 70℃) through the controlled prepolymerization process steps, so that the prepreg has suitable viscosity and lay-up properties at room temperature, which can meet the requirements of manual lay-up and automatic lay-up processes for complex curved surface components. At the same time, it avoids the shortening of the storage period caused by excessive prepolymerization, and achieves the synergistic unity of high lay-up properties, high viscosity and long cold storage period at room temperature. It provides a prepreg resin system that takes into account both processability and heat resistance for the preparation of high-performance high-temperature resistant composite material structural parts in aerospace, high-end equipment and other fields. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0020] The following is a detailed description of a bismaleimide composition, its preparation method, and its application provided by embodiments of the present invention.

[0021] This embodiment provides a bismaleimide composition, the raw materials of which, by weight, include: 60-100 parts of bismaleimide monomer, 20-60 parts of allyl-containing reactive comonomer, 10-40 parts of reactive modifier containing active unsaturated end groups, 0.5-2.5 parts of polymerization inhibitor and 15-25 parts of toughening agent.

[0022] The bismaleimide monomer includes at least one of aromatic diamine and polyamine maleimides; furthermore, in this embodiment, at least one of 4,4'-bismaleimide diphenylmethane, 4,4'-bismaleimide diphenyl ether, N,N'-m-phenylene bismaleimide, and domadiimide is preferably used. Aromatic bismaleimides have a highly conjugated aromatic skeleton, and after curing, they can form a heat-resistant network with a high crosslinking density, which is the core component to ensure the ultra-high Tg of the cured product.

[0023] The allyl-containing reactive comonomer includes at least one of diallyl bisphenol A, diallyl bisphenol S, and diallyl aniline. In this embodiment, the allyl-containing reactive comonomer has the dual functions of reactive diluent and comonomer. On the one hand, it can reduce the melt viscosity of the system and give it room temperature fluidity. On the other hand, it can participate in the construction of crosslinking network through olefin-imine addition copolymerization reaction during the curing process. However, its addition amount needs to be controlled within the specific range of this application. Adding too much will significantly reduce the Tg of the system.

[0024] The reactive modifier containing active unsaturated end groups includes at least one of heterocyclic polyenes and aromatic polyenes; specifically, in this embodiment, it includes isocyanurate series and polycyclic alicyclic cage double bond monomer series; the isocyanurate series preferably includes TAIC, THEICTA, and TALC; the polycyclic alicyclic cage double bond monomer series preferably includes IBOA, IBOMA, and EADMA. In this embodiment, the addition of the reactive modifier containing active unsaturated end groups under the above-mentioned specific conditions to the system can, on the one hand, reduce the melt viscosity of the system and impart room temperature fluidity; on the other hand, the reactive modifier containing active unsaturated end groups can participate in curing without reducing the Tg of the system, but its addition amount needs to be controlled within the specific range of this application, as excessive addition will shorten the storage life.

[0025] In this embodiment, the polymerization inhibitor preferably includes at least one of TEMPO, 4-hydroxyTEMPO, 4-butoxyTEMPO, and TEMPO ketone. In this embodiment, the polymerization inhibitor can rapidly capture carbon free radicals in the system at room temperature, and the two quickly combine to form inert covalent bonds, locking the free radicals, terminating chain growth, and completely preventing free radical polymerization at room temperature. At the same time, it undergoes homolytic decomposition at high temperature, releasing free radicals again. It not only no longer inhibits polymerization but can also assist in initiating double bond crosslinking. However, if too much is added, the residual small molecules will affect the Tg.

[0026] The toughening agent includes at least one of nitrile rubber, thermoplastic powder, and core-shell rubber. In this embodiment, the amount of toughening agent added needs to be controlled within a specific range. The more solid powder added, the worse the viscosity and the worse the dispersion effect, and the smaller the impact on mechanical properties. If too much liquid rubber is added, it will not only reduce mechanical properties, but also reduce strength and Tg.

[0027] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, comprising: (1) heating and mixing bismaleimide monomer and allyl-containing reactive comonomer at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 0.5-4 hours, and controlling the viscosity of the resin system at 70°C after prepolymerization to be 6000-20000 mPa·s to obtain a prepolymerized resin; (3) adding the prepolymerized resin and a reactive modifier containing active unsaturated end groups into a stirred tank and mixing evenly; (5) adding a toughening agent and a polymerization inhibitor, and stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition.

[0028] This embodiment also provides a bismaleimide prepreg, the preparation of which includes: hot-melt coating the above-mentioned bismaleimide resin composition at 60-80°C to form an upper resin film and a lower resin film, aligning the upper resin film, the reinforcing material fiber layer (including but not limited to carbon fiber cloth, glass fiber cloth, aramid fiber cloth and other high-performance fiber cloths) and the lower resin film in the order of vertical alignment, and impregnating them into heated pressure rollers at 90-100°C, and cooling to obtain a bismaleimide composition with a resin content of 35-42%.

[0029] In this embodiment, through the above-mentioned controlled prepolymerization process, the viscoelastic state of the resin system during the prepreg preparation stage can be precisely controlled within a specific window (viscosity of 3000-10000 mPa·s at 70°C), so that the prepreg has suitable viscosity and lay-up properties at room temperature, which can meet the requirements of manual lay-up and automatic lay-up processes for complex curved surface components. At the same time, it avoids the shortening of the storage period caused by excessive prepolymerization, and achieves a synergistic unity of high lay-up properties, high viscosity and long cold storage period at room temperature. This provides a prepreg resin system that takes into account both processability and heat resistance for the preparation of high-performance high-temperature resistant composite material structural parts in aerospace, high-end equipment and other fields.

[0030] The embodiments of the present invention will be described in detail below with reference to specific examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0031] Example 1 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5700), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hunan Fangruida), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0032] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1 part of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 7600 mPa·s).

[0033] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300, and lower resin film in the order of upper resin film, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0034] Example 2 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 100 parts of domatrix BMI resin (Chengdu Keyi CM5400), 20 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of IBOA (Arkema SR-506), 0.5 parts of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0035] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 100 parts of domatrix BMI resin and 20 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 8200 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of IBOA into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 0.5 parts of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 5700 mPa·s).

[0036] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 65°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 92°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0037] Example 3 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 60 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 60 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 35 parts of TAIC (Hunan Fangruida), 2 parts of TEMPO (Merck), and 15 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0038] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 60 parts of MMEA-type BMI resin and 60 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 30 min, controlling the viscosity of the resin system at 70°C after prepolymerization to be 6050 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 35 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 15 parts of toughening agent PI powder and 2 parts of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 3100 mPa·s).

[0039] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 60°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 90°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0040] Example 4 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 20 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 40 parts of TAIC (Hunan Fangruida), 2.5 parts of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0041] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 20 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2.5 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 16000 mPa·s, to obtain a prepolymerized resin; (3) adding the prepolymerized resin and 40 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 2.5 parts of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 8900 mPa·s).

[0042] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 76°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them in a heated pressure roller at 98°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0043] Example 5 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 50 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 10 parts of TAIC (Hunan Fangruida), 1 part of TEMPO (Merck), and 25 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0044] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 50 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 1.5 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 9100 mPa·s, to obtain a prepolymerized resin; (3) adding the prepolymerized resin and 10 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 25 parts of toughening agent PI powder and 1 part of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 6700 mPa·s).

[0045] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 67°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 93°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0046] Example 6 This embodiment provides a bismaleimide composition, the raw materials of which include, by weight, 80 parts of DDM type BMI resin (Chengdu Keyi CM7100), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 30 parts of TAIC (Hunan Fangruida), 1.5 parts of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0047] This embodiment also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of DDM type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 4 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 19960 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 30 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1.5 parts of polymerization inhibitor TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 9970 mPa·s).

[0048] This embodiment also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 80°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 100°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0049] Comparative Example 1 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of 2021S epoxy diluent (Hubei Zhenzhengfeng), 1 part of TBC (tert-butylcatechol reagent), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0050] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of 2021S into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1 part of polymerization inhibitor TBC, stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 8100 mPa·s).

[0051] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0052] Comparative Example 2 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hubei Fangruida), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0053] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 7600 mPa·s).

[0054] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0055] Comparative Example 3 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hubei Fangruida), 5 parts of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0056] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, to obtain a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of TAIC into a stirring vessel and mixing to obtain a homogeneous mixture; (4) adding 20 parts of toughening agent PI powder and 5 parts of TEMPO, stirring to obtain a homogeneous mixture at a temperature below 60°C, to obtain a bismaleimide resin composition (viscosity at 70°C is 7600 mPa·s).

[0057] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0058] Comparative Example 4 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0059] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding 20 parts of toughening agent PI powder and 1 part of TEMPO to the prepolymerized resin, stirring evenly at below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 12000 mPa·s).

[0060] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0061] Comparative Example 5 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 50 parts of TAIC (Hubei Fangruida), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials Polyimide Powder 3182).

[0062] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 50 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1 part of TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 3600 mPa·s).

[0063] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0064] Comparative Example 6 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hubei Fangruida), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials Polyimide Powder 3182).

[0065] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 6 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 50000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1 part of TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 45000 mPa·s).

[0066] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0067] Comparative Example 7 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hubei Fangruida), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0068] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting at 100°C to obtain a homogeneous resin mixture, the viscosity of the homogeneous resin mixture at 70°C being 2000 mPa·s; (2) adding the homogeneous resin mixture and 20 parts of TAIC into a stirring vessel and mixing to obtain a homogeneous mixture; (3) adding 20 parts of toughening agent PI powder and 1 part of TEMPO, stirring to obtain a homogeneous mixture at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C being 1030 mPa·s).

[0069] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0070] Comparative Example 8 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 50 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 70 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 5 parts of TAIC (Hubei Fangruida), 0.3 parts of TEMPO (Merck), and 10 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0071] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 50 parts of MMEA-type BMI resin and 70 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 6500 mPa·s, to obtain a prepolymer resin; (3) adding the prepolymer resin and 10 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 10 parts of toughening agent PI powder and 0.3 parts of TEMPO, stirring evenly at a temperature below 60°C to obtain a bismaleimide resin composition (viscosity at 70°C is 5780 mPa·s).

[0072] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 70°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 95°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0073] Comparative Example 9 This comparative example provides a bismaleimide composition, the raw materials of which, by weight, include: 80 parts of MMEA-type BMI resin (Chengdu Keyi CM5400), 40 parts of diallyl bisphenol A (Shaanxi Shuobo Electronics DABPA), 20 parts of TAIC (Hubei Fangruida), 1 part of TEMPO (Merck), and 20 parts of PI powder (Yushun New Materials polyimide powder 3182).

[0074] This comparative example also provides a method for preparing the above-mentioned bismaleimide composition, including: (1) adding 80 parts of MMEA-type BMI resin and 40 parts of diallyl bisphenol A into a mixing vessel, heating and melting them at 100°C to obtain a homogeneous resin mixture; (2) prepolymerizing the homogeneous resin mixture at 140°C for 2 hours, controlling the viscosity of the resin system at 70°C after prepolymerization to be 11000 mPa·s, and obtaining a prepolymerized resin; (3) adding the prepolymerized resin and 20 parts of TAIC into a stirring vessel and mixing them evenly; (4) adding 20 parts of toughening agent PI powder and 1 part of TEMPO, stirring evenly at a temperature below 60°C, and obtaining a bismaleimide resin composition (viscosity at 70°C is 7600 mPa·s).

[0075] This comparative example also provides a method for preparing a prepreg, comprising: hot-melt coating the above-mentioned bismaleimide resin composition at 100°C to form an upper resin film and a lower resin film, aligning the upper resin film, reinforcing material carbon fiber T300 and the lower resin film in the order of vertical alignment, impregnating them with heated rollers at 120°C, and cooling to obtain a bismaleimide prepreg with a resin content of 40%.

[0076] Experimental Example 1 The tack of the bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 was tested according to GB / T4852-2002 "Test Method for Initial Tack of Pressure-Sensitive Adhesive Tapes (Rolling Ball Method)" at 0 months, 1 month, 3 months, and 6 months. Grade A (less than 5 cm) was considered high tack, Grade B (5-15 cm) medium tack, and Grade C (greater than 15 cm) low tack. The test results are shown in Table 1. The tack of the prepregs prepared in Examples 1-6 and Comparative Examples 1-9 was tested according to GB / T 4852-2002 "Test Method for Initial Tack of Pressure-Sensitive Adhesive Tapes (Rolling Ball Method)" at 0 months and 6 months. Grade A (less than 5 cm) was considered high tack, Grade B (5-15 cm) medium tack, and Grade C (greater than 15 cm) low tack. The test results are shown in Table 1.

[0077] As shown in Table 1, for the bismaleimide composition, the tackiness of Example 1 remained excellent for 6 months, and the tackiness of the resin compositions provided in Examples 2-6 also remained at grade B or higher for 6 months. In the comparative examples, Comparative Example 1, lacking the reactive modifier and polymerization inhibitor containing active unsaturated end groups found in Example 1, showed tackiness loss after 6 months. In Comparative Examples 2 and 3, Comparative Example 2, without the addition of polymerization inhibitor, showed a significant decrease in tackiness after 6 months, reaching only grade C. In Comparative Example 3, the excess polymerization inhibitor still provided good storage performance, maintaining excellent tackiness for 6 months. In Comparative Examples 4 and 5, the absence of the reactive modifier containing active unsaturated end groups reduced the initial tackiness grade, but the presence of the polymerization inhibitor maintained grade B tackiness throughout the system for 6 months. However, Comparative Example 5, with the addition of an excess of the reactive modifier containing active unsaturated end groups, showed a significant decrease in storability. The loss of tackiness after 6 months indicates that the reactive modifier containing active unsaturated end groups causes the entire system to react slowly during storage, and even the presence of polymerization inhibitors cannot suppress the reaction. In Comparative Examples 6 and 7, the tackiness of the resin composition in Comparative Example 6 directly failed after 6 months due to excessive prepolymerization of the resin in the early stage, while the tackiness of the resin composition in Comparative Example 7, which did not undergo prepolymerization in the early stage, remained good after 6 months. In Comparative Example 8, the raw material formulation ratio was not within the range, resulting in poor storage properties and loss of tackiness after 6 months. In Comparative Example 9, the resin composition was the same as in Example 1, but the prepreg preparation process was different, and the results were consistent with Example 1. From the above data, it can be seen that the reactive modifier containing active unsaturated end groups greatly improves the initial tackiness but has poor storage properties, while polymerization inhibitors greatly improve storage properties. A reasonable ratio range can improve both the initial tackiness and maintain good storage properties.

[0078] Meanwhile, as shown in Table 1, for prepregs, in the schemes provided by this application, the prepreg provided in Example 1 still has a viscosity grade of A after 6 months, and the prepregs provided in Examples 2-6 have a viscosity grade of B or above after 6 months, indicating that the prepregs provided by this application still have good spreadability after a 6-month storage period. In the comparative examples, the prepregs provided in Comparative Examples 3, 4, and 7 have a viscosity grade of B or above after 6 months. In Comparative Examples 3 and 4, the presence of polymerization inhibitors helps with storage and the viscosity is maintained. In Comparative Example 7, the resin was not prepolymerized compared to Example 1, and the viscosity deteriorated when making the prepreg. Considering the large amount of powder, it was not prepolymerized into a homogeneous phase, resulting in a decrease in the surface viscosity grade. The prepregs provided in Comparative Examples 1, 2, 5, 6, and 8 have a viscosity grade of C or below after 6 months, and do not have spreadability, which is consistent with the casting. In Comparative Example 9, the baking temperature was increased, which may lead to free radical reaction, deactivation of the polymerization inhibitor, and ultimately poor storage performance.

[0079] Experiment Example 2 The bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 were subjected to a gelation test at 200 degrees Celsius. The gelation time of the bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 was tested at 0 months, 1 month, 3 months, and 6 months according to IPC-TM-650 2.3.18 gelation time test (hot plate drawing method). The test results are shown in Table 2.

[0080] As shown in Table 2, in the solutions provided in this application, the data results of Examples 1-6 indicate that the gel time variation of the resin composition is less than 10%, indicating good reaction stability of the resin system. In the comparative examples, Comparative Example 1, lacking the reactive modifier and polymerization inhibitor containing active unsaturated end groups as in Example 1, exhibited reactivity failure after 6 months, resulting in poor reaction stability after storage. In Comparative Examples 2 and 3, Comparative Example 2, without the addition of polymerization inhibitors, showed a significant decrease in gel time after 6 months. In Comparative Example 3, the excess polymerization inhibitor was still beneficial for storage, resulting in a small change in gel time and good reaction stability, but it would prolong the gel time and reduce activity. In Comparative Examples 4 and 5, although no reactive modifier containing active unsaturated end groups was added, the presence of polymerization inhibitors ensured overall... The gel time of the resins showed little change over 6 months. However, in Comparative Example 5, the reactivity failed after 6 months due to the addition of excessive reactive modifiers containing active unsaturated end groups. This indicates that the reactive modifiers containing active unsaturated end groups allow the entire system to react slowly during storage, and even the presence of polymerization inhibitors cannot suppress the reaction. In Comparative Examples 6 and 7, the gel time of the resin composition in Comparative Example 6 failed directly after 6 months due to excessive prepolymerization of the resins in the early stage. In contrast, the gel time of the resin composition in Comparative Example 7, which was not prepolymerized in the early stage, showed little change over 6 months. In Comparative Example 8, the resin composition was outside the formulation range, resulting in poor storage and failure of the reaction after 6 months. In Comparative Example 9, the resin composition was the same as in Example 1, but the prepreg preparation process was different, and the results were consistent with those in Example 1.

[0081] Based on the above data summary, reactive modifiers with unsaturated end groups are highly active and will slowly react with the system during room temperature storage, affecting the gel time. Polymerization inhibitors can inhibit the activity and prolong the gel time. A reasonable combination of reactive modifiers with active unsaturated end groups and polymerization inhibitors can control the reaction progress and stabilize the gel time.

[0082] Experimental Example 3 The viscosity of the bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 was tested using a cone-plate viscometer at 70°C for 0 months, 1 month, 3 months, and 6 months. The results are shown in Table 3.

[0083] As shown in Table 3, in the solutions provided in this application, the data results of Examples 1-6 indicate that the viscosity change of the resin composition is small, indicating good reaction stability of the resin system. In the comparative examples, Comparative Example 1, which lacks the allyl-containing reactive comonomer and polymerization inhibitor found in Example 1, has already cured after 6 months, resulting in viscosity loss and a large viscosity change after storage. In Comparative Examples 2 and 3, Comparative Example 2, without the addition of polymerization inhibitor, shows a significant increase in viscosity after 6 months. In Comparative Example 3, the excess polymerization inhibitor is still beneficial for storage, resulting in a small viscosity change and good reaction stability. In Comparative Examples 4 and 5, although no allyl-containing reactive comonomer is added, the presence of polymerization inhibitors results in a small viscosity change over 6 months. The viscosity of Comparative Examples 5 and 9 was reduced after 6 months due to the addition of excessive allyl-containing reactive comonomers, indicating that the allyl-containing reactive comonomers caused the entire system to react slowly during storage, and even the presence of polymerization inhibitors could not suppress the reaction. In Comparative Examples 6 and 7, the resin composition of Comparative Example 6 was cured after 6 months due to excessive prepolymerization of the resin in the early stage, and the viscosity was lost. In contrast, the viscosity of Comparative Example 7, which was not prepolymerized in the early stage, showed a small change after 6 months and was also lost. In Comparative Example 8, which was outside the formulation ratio range, the storage performance was poor, and the resin composition was cured after 6 months. In Comparative Example 9, the resin composition was the same as in Example 1, but the prepreg preparation process was different, and the results were consistent with those in Example 1.

[0084] Based on the above data summary, allyl-containing reactive comonomers can reduce initial viscosity, but they will also react slowly with the system during room temperature storage, causing the viscosity to increase. Inhibitors can suppress activity and reduce viscosity changes. A reasonable ratio of allyl-containing reactive comonomers and inhibitors can control the reaction and stabilize the viscosity.

[0085] Experiment Example 4 The thermal and mechanical properties of the bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 were tested: The bismaleimide resin compositions prepared in Examples 1-6 and Comparative Examples 1-9 were cured at a maximum temperature of 240℃ for 2 hours and cast into bodies; the Tg (obtained by the peak value of the loss modulus curve measured by dynamic viscoelastic spectrometry (DMA)), tensile strength (GB / T 3354-2014 "Tensile Properties Test Method for Directed Fiber Reinforced Polymer Matrix Composites"), flexural strength (GB / T 3856-2005 "Compression Properties Test Method for Unidirectional Fiber Reinforced Plastic Flat Plates"), and impact toughness (GB / T 1043.1-2018 "Determination of Impact Properties of Simply Supported Beams of Plastics Part 1: Non-Instrumental Impact Testing") of the cast bodies were tested before and after 6 months; the test results are shown in Table 4.

[0086] As shown in Table 4, in the solutions provided in this application, the data results of Examples 1-6 show that the mechanical properties of the resin compositions did not change significantly. In the comparative examples, Comparative Example 1 lacked the reactive modifier and polymerization inhibitor containing active unsaturated end groups found in Example 1, resulting in a low Tg and mechanical properties inferior to Example 1. It cured and failed after 6 months. In Comparative Examples 2 and 3, Comparative Example 2, which did not contain a polymerization inhibitor, showed a certain decrease in mechanical properties after 6 months. In Comparative Example 3, the excess polymerization inhibitor was still beneficial for storage, resulting in a small change in mechanical properties and good reaction stability, but both the initial Tg and mechanical properties decreased. In Comparative Examples 4 and 5, although no reactive modifier containing active unsaturated end groups was added, the presence of a polymerization inhibitor resulted in a small change in the mechanical properties of the entire resin after 6 months, but the absence of a reactive modifier containing active unsaturated end groups... The Tg of the reactive modifier with unsaturated end groups decreased significantly but did not exceed 300 degrees Celsius. However, the reactive modifier with excessive active unsaturated end groups in Comparative Examples 5 and 7 had already cured and failed after 6 months. In addition, the Tg and mechanical properties of Comparative Examples 5 and 7 were not as good as those in Example 1, indicating that the reactive modifier with excessive active unsaturated end groups affected the reaction competition relationship and thus affected the performance. In Comparative Examples 6 and 7, the resin composition of Comparative Example 6 had already cured after 6 months due to excessive prepolymerization of the resin in the early stage, while the mechanical properties of the resin composition of Comparative Example 7, which did not have prepolymerization in the early stage, showed little change after 6 months. In Comparative Example 8, the raw material formulation ratio was not within the range, and the storage performance was poor. It had already cured after 6 months. In Comparative Example 9, the resin composition was the same as that in Example 1, but the prepreg preparation process was different, and the results were consistent with those in Example 1.

[0087] Based on the above data summary: reactive modifiers containing active unsaturated end groups can significantly improve the Tg of the system, but excessive addition will affect the reaction and reduce Tg; excessive polymerization inhibitors, as small molecules, have a reducing effect on Tg; a suitable ratio of reactive modifiers containing active unsaturated end groups to polymerization inhibitors can achieve high Tg and mechanical properties in the resin system, while also providing long storage life.

[0088] Experimental Example 5 The mechanical properties of the prepregs prepared in Examples 1-6 and Comparative Examples 1-9 were tested: The prepregs prepared in Examples 1-6 and Comparative Examples 1-9 were cured at a maximum temperature of 240℃ for 2 hours, with a resin content of 40% and a thickness of 2 mm, unidirectional (0°). The Tg (obtained by the peak value of the loss modulus curve measured by dynamic viscoelastic spectrometry (DMA)), tensile strength (GB / T 3354-2014 "Tensile Properties Test Method for Directed Fiber Reinforced Polymer Matrix Composites"), flexural strength (GB / T3856-2005 "Compression Properties Test Method for Unidirectional Fiber Reinforced Plastic Flat Sheets") and shear strength (GB / T 3355-2014 "Longitudinal and Transverse Shear Tests of Polymer Matrix Composites") were tested before and after 6 months. The test results are shown in Table 5.

[0089] As shown in Table 5, the prepreg products provided in Examples 1-6 of the scheme provided in this application did not show significant changes in their mechanical properties after 6 months, meeting the product requirements. The prepregs provided in Comparative Examples 1, 5, 6, 8, and 9 were deactivated after 6 months and could not be prepared, failing to meet the product requirements. The prepreg provided in Comparative Example 2 showed a significant decrease in Tg after 6 months, and other properties also decreased. The mechanical properties of Comparative Example 7 did not show significant changes.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bismaleimide resin composition, characterized in that: The raw materials, by weight, include: 60-100 parts of bismaleimide monomer, 20-60 parts of allyl-containing reactive comonomer, 10-40 parts of reactive modifier containing active unsaturated end groups, 0.5-2.5 parts of polymerization inhibitor, and 15-25 parts of toughening agent.

2. The bismaleimide composition according to claim 1, characterized in that: The reactive modifier containing active unsaturated end groups includes at least one of heterocyclic polyenes and aromatic polyenes.

3. The bismaleimide composition according to claim 2, characterized in that: The reactive modifier containing active unsaturated end groups includes at least one of TAIC, THEICTA, TALC, IBOA, IBOMA, and EADMA.

4. The bismaleimide composition according to claim 1, characterized in that: The polymerization inhibitor includes at least one of TEMPO, 4-hydroxyTEMPO, 4-butoxyTEMPO, and TEMPO ketone.

5. The bismaleimide composition according to claim 1, characterized in that: The bismaleimide monomer includes at least one of aromatic diamine and polyamine maleimides.

6. The bismaleimide composition according to claim 1, characterized in that: The allyl-containing reactive comonomer includes at least one of diallyl bisphenol A, diallyl bisphenol S, and diallyl aniline.

7. The bismaleimide composition according to claim 1, characterized in that: The toughening agent includes at least one of nitrile rubber, thermoplastic powder, and core-shell rubber.

8. A method for preparing the bismaleimide composition according to any one of claims 1-7, characterized in that: include: (1) The bismaleimide monomer and the allyl-containing reactive comonomer are heated and mixed evenly at 100°C to obtain a homogeneous resin mixture; (2) The homogeneous resin mixture is prepolymerized at 140°C for 0.5-4 hours, and the viscosity of the resin system after prepolymerization at 70°C is controlled to be 6000-20000 mPa·s to obtain prepolymerized resin. (3) The prepolymer resin and the reactive modifier containing active unsaturated end groups are added to a stirred tank and mixed evenly; (4) Add the toughening agent and the polymerization inhibitor, and stir evenly at a temperature below 60°C to obtain the bismaleimide resin composition.

9. A bismaleimide prepreg, characterized in that: The preparation includes: hot-melt coating the bismaleimide resin composition according to any one of claims 1-7 at 60-80°C to form an upper resin film and a lower resin film; aligning the upper resin film, the reinforcing fiber layer and the lower resin film in the order of the upper resin film, the reinforcing fiber layer and the lower resin film; impregnating the mixture with a heated roller at 90-100°C; and cooling to obtain the bismaleimide prepreg with a resin content of 35-42%.

10. The application of the bismaleimide prepreg of claim 9 in the preparation of high-performance high-temperature resistant composite structural parts.

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